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2016 Quarter 2 Vol. 2, No. 2

UV-Curable Clearcoat in Commercial Aviation Monitoring of Property Development

Material Strategies for Food Packaging

Developments in Soft-Touch Coatings

Official Publication of RadTech International North America

We create chemistry that makes surfaces love UV curing.

In close collaboration with our customers and their value chain networks, we search for solutions to meet the market needs of today and the challenges of tomorrow. Our technical experts provide advice on ink, overprint varnish and coating guidelines to develop the best solutions leading to faster curing rates, good adhesion to a wide range of substrates, increased productivity and lower production costs. At BASF, we create chemistry.

See us at

RadTech 2016 Booth #807, May 16-17 in Chicago.

Polymeric Photoinitiators UV Inks and Coatings for Food Packaging

When it comes to food packaging for indirect contact, odor and the potential migration of mobile components are a concern for every formulator. RAHN‘s GENOPOL* polymeric photoinitiator range is the answer.

RAHN AG, Zurich, Switzerland RAHN GmbH, Frankfurt am Main, Germany RAHN USA Corp., Aurora, Illinois, USA RAHN Trading (Shanghai) Co. Ltd., Shanghai, China


RadTech 2016 The world’s largest event dedicated to the educational, technical and scientific advancement of ultraviolet (UV) and electron beam (EB) technologies. May 16-18, 2016, Chicago, Illinois


Raw Material Strategies for Food Packaging Compliance UV and EB formulations have the potential to migrate from the coating to the coated product, with implications for food packaging. By Susan E. Bailey, Ph.D., technical manager, North America, IGM Resins



Soft-touch coatings have received renewed interest from brand owners in a variety of markets, with a need for a UV-curable system with increased resistance to mars, abrasions, stains and chemicals compared to conventional systems. By Xavier Drujon, Lisa Spagnola and Gunter Moeller, Sartomer

Cover photo copyright © Boeing. The cover was finished by Royle Printing Company, Sun Prairie, Wisconsin, using a multi-step UV-curing process called Rough Reticulated Strike-Through. First, the 4-color process was laid down and a UV varnish was applied as a spot application in the areas that did not receive the gloss UV treatment (photograph and copy). The UV varnish was cured with UV lights, and then an LED curing system was used to cure the 4-color process inks. A flood gloss UV was applied over the entire cover, which “reacted” to the UV varnish and created the matte varnish – staying glossy in the areas that were knocked out to receive the gloss UV. The final step was a pass under another UV curing system to cure the coating. This process was performed in one pass on press.

DEPARTMENTS President’s Message............................................. 4 Association News................................................. 6 Industry News..................................................... 24 Regulatory News................................................ 52 Technology Showcase........................................ 54 Calendar.............................................................. 56 Advertisers’ Index............................................... 56

Most Recent Developments in UV-Curable Soft-Touch Coatings


Simultaneous Monitoring of Property Development and Reactive Group Conversion in Photopolymer Systems Measurement of functional group conversion is important in determining performance under a given set of conditions, while monitoring the dynamic progress of conversion to more accurately gain information about network development also is key. By Parag K. Shah, University of Colorado Boulder, and Jeffrey W. Stansbury, University of Colorado Denver


Heat-Resistant, UV-Curable Clearcoat for Aircraft Exteriors Potential opportunities were identified for using very-fast-curing exterior aircraft paints to reduce paint process cycle time and improve finish quality and durability for the airline customer. By Richard W. Baird, senior chemical engineer and project manager, The Boeing Company


Understanding Ultraviolet LED Wavelength As a result of high demand for UV-A diodes, most UV LED development work has been focused on 365-405nm. By Mike Higgins, east regional sales manager, Phoseon


RadTech Winter Meeting Offers Committee Updates RadTech’s Winter Meeting, held in February, provided valuable updates on program and committee direction. By Dianna Brodine, managing editor, UV+EB Technology

2 | UV+EB Technology • Issue 2, 2016 +


RadTech International North America’s Editorial Board facilitates the technical articles featured in UV+EB Technology. Smaller teams of Issue Champions review and approve articles and provide overall content management for each issue, as needed. If you are a member of RadTech and are interested in serving on the Editorial Board, contact Gary Cohen at

Susan Bailey

Technical Development Manager, Acrylates IGM Resins

Syed T. Hasan

Manager, New Business Development & Idea Management – Dispersions & Pigments BASF Corporation


UV-Curing Technology Question & Answer

Is there a “quick and easy” way to estimate the UV exposure under a UV LED lamp? By R.W. Stowe, director of applications engineering, Heraeus Noblelight America LLC


EB-Curing Technology Question & Answer

What types of applications are enabled by sealed tube EB lamp technology? By Stephen C. Lapin, Ph.D., PCT Engineered Systems, division of Ebeam Technologies, Comet Group

Chris W. Miller

Editorial Board Co-Chair Manager, Research & New Technology Estron Chemical

Maria Muro-Small

Director of Marketing Spectra Group Limited, Inc.

UV+EB TECHNOLOGY EDITORIAL BOARD Chris W. Miller, Estron Chemical Co-Chair/Editor-in-Chief James Zawicki, Sartomer Americas Co-Chair/Editor-in-Chief Susan Bailey, IGM Resins Brian Cavitt, Abilene Christian University Byron Christmas, Professor of Chemistry, Retired Syed Hasan, BASF Corporation Charlie He, Full Spectrum Laser LLC Mike Higgins, Phoseon Technology Molly Hladik, ACTEGA North America +

Mike J. Idacavage, Colorado Photopolymer Solutions Stephen Lapin, PCT Engineered Systems, Comet Group Sudhakar Madhusoodhanan, Valspar Maria Muro-Small, Spectra Group Limited, Inc. R.W. Stowe, Heraeus Noblelight America LLC Huanyu Wei, FiberMark Jinping Wu, PolyOne Corporation Sheng “Sunny” Ye, 3M

Sheng “Sunny” Ye

Senior Research Engineer 3M Corporate Research Process Laboratory - UV Processing Group

James Zawicki

Editorial Board Co-Chair Marketing Communications Manager Sartomer Americas

UV+EB Technology • Issue 2, 2016 | 3

President’s Message UV/EB: a niche technology? That is how many of us view our corner of the industrial technology world. It may be a niche, but it is a niche with a pretty broad range of potential applications. Many of these applications are on full display at RadTech 2016. Special sessions on new automotive applications, food packaging regulations, wood and hydrogels attest to the fact that manufacturing has found a wide range of uses for our Peter Weissman technology. A special panel on “innovation” at the event brings to the fore the underlying importance of UV/EB and the real value of RadTech – the adoption of UV/EB is not simply moving to a new type of paint or coating. Instead, it requires companies to engage in a much deeper evaluation of their processes and products. Such company “re-engineering” has helped manufacturers continue to evolve, becoming more sustainable and competitive. We can see this rethinking of how things are made in our RadTech 2016 Emerging Technology award winners. At RadTech 2016, the association honors companies developing new 3D printing materials, innovating with holographic films and using electron beams and UV LEDs to make new products with new processes. Making new things also is a powerful message to university students from schools including MIT, Northwestern and the University of Connecticut as they bring to RadTech 2016 their work with applications that include a type of medical implant and a device for medical tissue engineering. In fact, in this issue of the magazine, the same diversity is on display, with articles on Heat-Resistant UV-Curable Clearcoat for Aircraft Exteriors from Boeing and Most Recent Developments in UV-Curable Soft-Touch Coatings. These are two seemingly very different applications for our technology, connected by the use of UV. We hope you join our efforts to help expedite innovation and discovery in new materials and processes. Our “niche” technology has found its way into applications that touch nearly every aspect of our lives, demonstrating how widespread our technology has become.

TECHNOLOGY An official publication of: RADTECH INTERNATIONAL NORTH AMERICA 7720 Wisconsin Avenue, Suite 208 Bethesda, Maryland 20814 240-497-1242 EXECUTIVE DIRECTOR Gary M. Cohen SENIOR DIRECTOR Mickey Fortune


President Peter Weissman – Quaker Chemical Corporation President-elect Lisa Fine – Joules Angstrom UV Printing Inks Secretary Eileen Weber – Red Spot Treasurer Paul Elias – Miwon North America Immediate Past-President Don Duncan – Wikoff Color Corporation Board of Directors Jo Ann Arceneaux – Allnex USA Inc. Rick Baird – The Boeing Company Mark Gordon – INX International Ink Company Jennifer Heathcote – Phoseon Technology Joshua Lensbouer – Mannington Mills George McGill – Zeller + Gmelin Corporation Alexander Polykarpov – AkzoNobel Beth Rundlett – Katecho, Inc. Jeremy Teachman – Sun Chemical Corporation Alrick “Al” Warner – Procter and Gamble Xiasong Wu – DSM Functional Materials

Published by:

Peter Weissman President, RadTech International North America Quaker Chemical Corp.


gi automotive ta plastics l 3D/SLA _pr aviation electronics int in g n i h s i n g wood_fi medical_device food_packaging 4 | UV+EB Technology • Issue 2, 2016

2150 SW Westport Drive, Suite 101 Topeka, Kansas 66614 785-271-5801 Publisher Jeff Peterson

National Sales Director Janet Dunnichay

Art Director Becky Arensdorf

Managing Editor Dianna Brodine

Contributing Editors Circulation Manager Kelly Adams Brenda Schell Nancy Cates ENews & Website Developer Jen Clark +

We unlock the potential of UV/LED light and transform its power You have a unique curing need, the product specifications are extremely precise, and the manufacturing process runs 24/7. You need a UV/LED curing specialist who understands your growing needs and will help you meet the demands of your ever-changing marketplace. For over two decades Honle UV America has been raising the bar in the development of new UV/LED curing technology that has made the printing, coating, and adhesive assembly industries worldwide more profitable. Our expertise lies in unlocking the potential of UV/LED light and transforming its power into a variety of custom engineered curing solutions that will maximize your productivity and profitability. Our expert engineers are on hand for on-site evaluations, they’ll make recommendations on UV/LED equipment, and support you and your staff throughout the life of our products. LED Powerline Flexo

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261 Cedar Hill Street, Marlboro, MA 01752 508 . 229 . 7774 •

Association News Susan Bailey Joins RadTech Board of Directors Susan Bailey, technical director – North America for IGM Resins, has been appointed to the RadTech Board of Directors, effective immediately. Bailey has been with IGM Resins since 2014 and is a long-standing contributor to the RadTech organization. Her industry experience includes product development of chemical components, adhesives, coatings and inks in diverse markets of printing, pharmaceutical and electronics. Bailey has been a part of the RadTech Editorial Board since 2008 and a participant in RadTech Conference Short Courses since 2010. She has contributed to the SUNY-ESF Radiation Curing Program since 2012. RadTech Releases New Version of UV-LED eBook RadTech, the trade association for UV and EB technology, has released an expanded version of the group’s wildly popular UV-LED eBook. This updated version includes new articles and papers on the following: • Applications and Market Trends • Operation and Output Measurement 2015 Quarter 3 Vol. 1, No. 3

2015 Quarter 2 Vol. 1, No. 2

2015 Quarter 4 Vol. 1, No. 4


Printing & Packaging Innovati ons Wood Fin ishi Technolog ng y

EB Application Advancements



UV/EB leading the way for the future of automotive UV for Surface Protection

Carbon Footprinting & Sustainability

UV/EB & Flexible Electronics

Official Publication of RadTech

Official Publication of RadTech International

North America

UV-Inkjet on nicFood Acous Assisted Drying tically Packaging

Waterb Next Generation orne UV-Cu rable CoatingsEsters Cellulose Nanogel Additiv e PhotopolymerBUYE RS Modifi GUID cation E EDITION

International North America

Official Publica

tion of RadTec

h Internat

ional North


SHARE YOUR KNOWLEDGE WITH OUR READERS UV+EB Technology, the official magazine of RadTech International North America, promotes the use and benefits of ultraviolet and electron beam curing technologies. It is distributed to more than 15,000 readers, including end users, formulators, raw material suppliers and service providers on a quarterly basis.

SUBMIT AN ARTICLE FOR CONSIDERATION UV+EB Technology features non-commercial content, including technical articles, case studies, application highlights and Q&As. All technical content is reviewed by RadTech’s Editorial Board. For complete editorial guidelines:

6 | UV+EB Technology • Issue 2, 2016

• Curing Systems • Diode Evolution and Manufacturing • Chemistry • UV-C LEDs Download the ebook at Rita Loof Honored as 2015 Mother of Achievement The Mother of Achievement award recognizes those outstanding women whose positive influence, talents and community service have made a significant impact in the lives of children and families. Rita Loof, RadTech’s director of regional environmental affairs, has been named as the California awardee. Loof has 25 years of experience in the field of air quality compliance, four years of experience as a permit processing engineer for the South Coast Air Quality Management District (SCAQMD) and more than 20 years of consulting experience for private industry. She has written a Technical Guidance Document on permit processing of semiconductor operations for SCAQMD engineers and conducted training seminars for SCAQMD engineers on permit processing. Loof has extensive volunteer experience with various nonprofits that advocate for the educational rights of children with disabilities. She authored legislation to strengthen protections for children with disabilities attending private schools, which ultimately became law with bipartisan support. Her efforts have been recognized by The Arc (a nonprofit organization for people with developmental disabilities), the United States Department of Education and the California Legislature. American Mothers, Inc.® is committed to valuing mothers through service and education and has been MomStrong since 1935. For more information, visit Chunlin (Charlie) He Joins RadTech Editorial Board Chunlin (Charlie) He, Ph.D., is the newest member of the RadTech Editorial Board, which provides guidance and support in the publication efforts of the association, including article review for UV+EB Technology. He is the lead materials scientist for Full Spectrum Laser, LLC, Las Vegas, Nevada, working on research and development of materials for 3D printing applications. He holds a Ph.D. in materials chemistry, University of Colorado Boulder; M.S., organic chemistry, Zhejiang University, Hangzhou, China; and B.S., chemistry, Nanchang University, Nanchang, China. u


RadTech Korea Announces 2016 Conference RadTech Korea recently announced the date for its 11th annual conference, which will be June 16, 2016, at Gyeonggi Technopark in Ansan City, Gyeonggi Province, Korea. The daylong event will feature 40-minute presentations on a range of topics. For more information, email or visit u +



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EXHIBITING COMPANIES Aal Chem Alberdingk Boley, Inc. Allnex American Ultraviolet BASF Corporation BYK Additives & Instruments CB Mills Division of Chicago Boiler Co. CFCM Magazine Changzhou Tronly New Electronic Materials Co., Ltd. Chitec Technology Co, Ltd. Clearstone Technologies Collins Inkjet Colorado Photopolymer Solutions Daicel (U.S.A.), Inc. Digital Light Lab DSM Dymax Oligomers & Coatings Dyna-Tech Adhesives EIT Instrument Markets Enercon Industries Corporation Energy Sciences Inc. Excelitas Technologies (OmniCure) FlackTek, Inc. GEW Inc. Hamamatsu Corporation Hampford Research Heraeus Noblelight America LLC. High Power Lighting Corp. Honle UV America IGM Resins Innovations In Optics, Inc. IRTronix, Inc. Isuzu Glass, Inc. Keyland Polymer Kopp Glass Kromachem Inc. Lambson Ltd. Melrob US Inc. Miltec UV Miwon North America Nedap Light Controls NETZSCH Instruments North America, LLC NICHIA Corporation Nordson Corporation Opsytec Dr. Gröbel GmbH Paint + Coatings Industry PCT Engineered Systems Phoseon Technology PL Industries Prime Coatings RAHN USA Corporation Red Spot Paint & Varnish Co. Sartomer Americas Seoul Viosys Co., Ltd. Shamrock Technologies Siltech Corporation Spectra Group Limited, Inc. Strathmore Products Sunlite Science & Technology, Inc. Synasia Inc. Unimin Specialty Minerals, Inc. Ushio America UV CHEM-KEYS CO., LTD

TECHNOLOGY EXPO & CONFERENCE May 16-18, 2016 Hyatt Regency O’Hare - Chicago, IL

Join the Manufacturing Revolution with UV+EB Technology With the rapid emergence of LED technology and new breakthroughs in materials and equipment, check out some of the exciting topics we will present at RadTech 2016! 3D Printing Automotive Biomedical Conductive Inks Exterior Applications Food Packaging Inkjet Digital Printing

Lightweighting Low Migration Metal Coil Coatings Nanoimprinting Adhesives Roll to Roll Processes Soft Touch Wood Products

UV+EB Technology is pointing the way toward exciting breakthroughs in a multitude of science, technology, and manufacturing applications. Learn more at


* Schedule subject to change. For the current program, visit

Registration Express Check-In: 7 a.m. - 6 p.m. Conference Sessions: 8 a.m. - 4 p.m. Exhibition: 10 a.m. - 6 p.m. Opening Reception: 5 p.m. - 6 p.m.



3D Printing 8:00 AM - 10:00 AM Specialty Applications 10:00 AM - Noon Printing and Packaging 1:00 PM - 3:00 PM Digital Printing 3:00 PM - 5:00 PM

Formulation 8:00 AM - 10:00 AM Hardcoats 10:00 AM - 12:00 PM Coatings 1:00 PM - 3:00 PM Adhesives 3:00 PM - 5:00 PM

Tuesday, May 17, 2016

Registration Express Check-In: 7 a.m. - 6 p.m. Conference Sessions: 8 a.m. - 4 p.m. Exhibition: 10 a.m. - 6 p.m. President’s Reception: 5 p.m. - 6 p.m. Emerging Awards Dinner: 6 p.m. - 8 p.m.



Chemistry 8:00 AM - 10:00 AM

Advances in Electron Beam Equipment and Applications 8:00 AM - 10:00 AM Electron Beam Technology for Packaging Applications Enviro, Health, & Safety 10:00 AM - 12:00 PM 10:00 AM - 12:00 PM Raw Materials I Deep UV LED 1:00 PM - 3:00 PM 1:00 PM - 3:00 PM Raw Materials II Equipment 3:00 PM - 5:00 PM 3:00 PM - 5:00 PM

Wednesday, May 18, 2016

Registration Express Check-In: 7 a.m. - 2 p.m. Conference Sessions: 8 a.m. - 2 p.m. Exhibition: 10 a.m. - 2 p.m.



Low-Gloss / Haptic Coatings 8:00 AM - 10:00 AM Composites 10:00 AM - 12:00 PM Global Market Overview 1:00 PM - 3:00 PM

Photoinitiator 8:00 AM - 10:00 AM Waterborne 10:00 AM - 12:00 PM Cure Studies 1:00 PM - 3:00 PM

Check o ut the Sun day Short Courses !

RADTECH International North America 7720 Wisconsin Avenue, Suite 208 | Bethesda, Maryland 20814 P: 240-497-1242 |


Q. Is there a “quick and easy” way


to estimate the UV exposure under a UV LED lamp?


All manufacturers of UV LEDs packaged for UV curing provide a specification of the irradiance or peak irradiance under the lamp, and typically at specific distances from the lamp face (watts/cm²). The model of the LED identifies the nominal wavelength. But, what about exposure at various speeds? Perhaps an integrating radiometer (dosimeter) is not available. Many LED curing systems position the LEDs at 2 to 20mm from the work surface. What if the distance between the lamp and the work is too small for an integrating type radiometer or dosimeter? Or, what if one simply can’t be sent through the system? If you have a very thin, probe-type radiometer with a wavelength response that covers the particular LED, then you may be able to “map” the irradiance profile, as in Figure 1. This involves repositioning the probe carefully at many equally spaced points and making the following calculation:

Where E is the exposure, in J/cm²; v is the desired velocity in inches/second (or mm/s); i is the irradiance at each measurement point; and Δd is the increment of distance in inches (or mm).

FIGURE 1. Series of static irradiance measurements made with NobleProbe® of 15W/cm²|44mm|385nm UV Lamp made at 0.1-inch intervals, at 2mm distance and 0.5-inch distance

Spectral Exposure is the time-integral of Irradiance (area under the curve)

But, I promised a quick and easy method. The profile is unlike most medium-pressure mercury lamps that have a sharply-peaked profile and irradiance that “tails” on either side of the peak. The shape of these profiles and 10 | UV+EB Technology • Issue 2, 2016

FIGURE 2. Characteristic irradiance profiles of tubular lamps with focusing reflectors — typical of medium-pressure mercury and additive types of lamp +

“When examining the typical LED profiles, observe that the space above the curve inside and the space below the curve outside of the 50% points are similar.”

E is exposure in joules per cm² (J/cm²); Ip is peak irradiance under the lamp head in watts per cm² (W/cm²) at a specific distance; D is the distance (in the travel direction) between the 50% irradiance points, in inches (or mm) [This is approximately the width of the LED array and may be similar to, but smaller than, the window dimension]; and v is the velocity of the surface under the lamp, in inches per second (or mm/s). This method gives a good approximation of the exposure under an LED, or several LEDs, when a dosimeter or an integrating radiometer is not practical or available. n

the “tails” make it difficult to calculate exposure (Figure 2). To find the area under the curve, which is proportional to exposure, we are usually forced to use an integrating radiometer. LEDs are arrays of packed LED dies, so they usually have a characteristically “soft” irradiance profile. Profiles will be similar, even if the array has some concentrating optics applied. When examining the typical LED profiles, observe that the space above the curve inside and the space below the curve outside of the 50% points are similar – they have similar areas. This leads to a very rough approximation: E = Ip x D/v

R.W. Stowe

Director of Applications Engineering Heraeus Noblelight America LLC

Expand your knowledge base. Browse the UV+EB Technology and RadTech Report archives. +

UV+EB Technology • Issue 2, 2016 | 11


Q. What types of applications are

enabled by sealed tube EB lamp technology?


Low energy self-shielded electron beam (EB) systems have been used in industrial applications for more than 30 years. Early systems operated mostly in the 175 to 300 kV range and were designed for web processing up to about 3 meters wide. These systems were large and expensive, but were a good fit for many applications including crosslinking of polyethylene-based films for heat shrink packaging. This equipment also was being used for curing inks and coatings for package printing applications, but was really overdesigned for this use. A new generation of smaller EB systems operating from about 80 to 125 kV were introduced in the early 1990s. This lower voltage equipment was wellsuited for curing thin ink and coating layers. These first- and second-generation systems share some common features in that both use multifilament cathodes contained in a vacuum chamber. Electrons are accelerated through metallic window foils, which separate the vacuum chamber from the product being treated at atmospheric pressure. These foils are held in place with O-rings and mechanical clamps. The vacuum is maintained by continuously operated vacuum pumps. Periodic replacement of windows foils is part of the normal maintenance for these systems. Another new type of EB system also was being pioneered by inventor Tovi Avnery in the late 1990s and early 2000s. This evolved into a startup company, Advanced Electron Beams (AEB). The AEB emitter was quite different from the early generation EB systems in that the new systems used a sealed window foil (not clamped) and maintained a permanent vacuum, eliminating the need for vacuum pumps. Rather than replacing window foils, new emitters were designed to “plug-in” in the event of an emitter failure. Failed emitters were returned and rebuilt at the factory. This concept was more like a “lamp” than a traditional EB system. The compact AEB emitters were initially available in 250 to 400 mm widths and were a small fraction of the size of the actively pumped systems. AEB produced a few hundred emitters and established some new applications, but eventually went out of business.

12 | UV+EB Technology • Issue 2, 2016

Following the demise of AEB, the development of optimized industrial sealed tube EB “lamps” was completed by the Comet Group. Design improvements were facilitated by Comet’s long history and experience in metal/ceramic industrial X-ray tubes. These lamps are currently available in 270 and 400 mm widths with accelerating potentials of 80 to 200 kV. Long lamp life (minimum of 6000 hours) has been proven even under severe cycling and use conditions. The development of reliable EB lamps has created opportunities for new EB applications. EB Lab Systems: The large industrial EB systems are still widely used today. These systems are not well suited for product development in a laboratory environment due to the size, cost, and utility requirements. The industrial systems are also mostly designed for high-speed web processing, whereas handling of individual sheets, panels, or parts is often preferred for laboratory testing. Compact selfcontained EB lab systems using EB lamps are now readily available to meet this need. The systems can handle A4 size sheets and parts up to 50 mm high. Dose and voltage can be adjusted to match beam conditions used in largescale industrial EB equipment. In-Line Package Sterilization: The use of EB to sterilize packaging is well known. High energy (1 to 10 MeV) EB is being used to sterilize full cases of packaged pharma and medical products. The high-energy equipment is very large, expensive, and requires conveyors within a shielded vault. These service facilities operate off-site from the product manufacturing and packaging. Compact EB lamps are ideal for sterilizing surfaces of packaging or of a product before it is packaged. Consequently, low energy (80-200 kV) lamps enable in-house and in-line sterilization of pharma and medical products and packaging. Because the lamps are a good size to match individually packaged products, they integrate well into lines in which products are EB treated and maintained within a sterile zone for subsequent processing, packaging or sealing. Chemical-free EB sterilization offers an attractive alternative to sterilization with hydrogen peroxide, ethylene oxide, or steam. +

Narrow Web Printing: The use of traditional EB systems for wide web curing of inks and coatings for package printing applications is well known. The consistent beam output and photoinitiator-free formulations make EB attractive for use in food packaging applications. Narrow web printing is also an important process for the production of tags, labels, packets, tickets, lidding, etc. Historically, migration has been a lower concern for these markets; however, there is a growing EB lamp (front/center), power supply and cooling unit concern about migration for labels and other narrow web-printed packaging. Interest in digital printing is growing rapidly, driven by the demand for short runs of custom-printed packaging. Initial growth in digital package printing is occurring in narrow web formats. Rapid growth is expected for EB curing of inkjet inks and EB coatings on electrographic digital printed packaging. The fit of EB technology with digital printing will be the subject of future articles. EB Curing on Three-Dimensional Parts: EB has been predominantly used for curing of coatings, adhesives or parts conveyed through the EB units on a continuous web. Webs can be readily processed through EB systems using compact shielding and low volumes of gas for inerting.

shielding and inerting during this 3D curing process. Initial targets include curing inks (conventional and digital) on relatively simple objects including bottles, cans, and tubs. EB curing on more complex parts, using multiple lamps systems, also is expected. EB lamps certainly are a game-changing technology. Many new applications are expected that were not possible with traditional EB systems. u

Compact EB lamps offer the potential to change this paradigm. Lamps can be configured and used together with automated product handling to present all surfaces that require curing within the needed proximity of the beam window. Systems have been designed to maintain product

Stephen C. Lapin, Ph.D.

BroadBeam Applications Specialist, PCT Engineered Systems, division of ebeam Technologies, Comet Group +

UV+EB Technology • Issue 2, 2016 | 13

MATERIAL STRATEGIES By Susan E. Bailey, Ph.D., technical manager - North America, IGM Resins

Raw Material Strategies for Food Packaging Compliance UV

and EB formulations convert under radiation exposure from a liquid composition to a solid material. The compositions can be complex mixtures. Any components that do not react to incorporate into the polymer network are trapped within it; however they have the potential to migrate from the coating with exposure to heat, contact with similar materials or over time. Even though these components are minute constituents of the final film, they can affect the coating performance and that of the coated product. In certain applications, the chemicals released are regulated and need to be strictly controlled. A concerted strategy of raw material selection and characterization of product performance under life cycle conditions should be used to achieve the desired low migration outcome. First, consider the components that can migrate. After the cure reaction, many components are chemically bound. Residual monomer and photoinitiator molecules remain unbound in the coating. Formulation additives that are not intended to participate in the polymerization are also unbound. Many formulation components will contain stabilizers as well as residual components of their own synthetic manufacture. Migration can occur through a few basic mechanisms. The most common mechanisms that affect food packaging are outlined in Table 1. The migrating species can penetrate into the substrate that was coated. An example of this is the diffusion of migrating components into the substrate leading to embrittlement of the coating. The porosity of the substrate, as well as the similarity between the substrate and the coating components, can influence this migration. Migration also can occur during direct contact of a new surface and the radiation-cured coating. An example of the effect is the transfer of migrating species into food products that can occur when this contact is made between the printed and nonprinted side of food packaging. Migration of residual components from the coating surface into the new substrate tends to drive this process that is typically dependent on the time of TABLE 1. Examples of Mechanisms of Migration

14 | UV+EB Technology • Issue 2, 2016 +

The Nestlé guidance note is an additional list of components, registered on the Swiss Ordinance list, that must be excluded from ink formulations.

contact. Elevated temperature product use environments lead to the evaporation of volatile residual components and migration to the coating surface. External heat examples include boil-in-bag food packaging and sterilization processes. Migrating species are controlled by regulation from several directions. In the application example of food packaging, the US Food and Drug Administration (FDA) Code of Federal Regulations (CFR) Title 21 parts 170-199 in particular chapters 175.300, 175.320, 176.170 and 176.180 are applicable. Evidence for low risk of food contamination is established by extensive characterization of the product (the printed and converted package) during the intended use. An example of this process for radiation-cured materials is Food Contact Notification (FCN) 772. The European regulations that control migration of substances into food include Framework Regulation (EC) No 1935/2004 and EU Regulation (EC) No 10/2011. The first defines prohibited migration into food products while the second assigns specific migration limits (SML). The “Ordinance of the FDHA on Materials and Articles (817.023.21) is the implementation by Switzerland commonly known as the Swiss Ordinance List. The ordinance list consists of several annex documents. For food packaging, Annex 6 is applicable. Annex 6 is a positive list for all other substances used in food packaging and is divided in two parts. Part A lists substances that are evaluated and can be used for printing inks. Many materials will have an SML (mg/kg) reported for maximum migration. For the materials on the Part A list without an SML, then a migration maximum of 60 mg/kg is set. Part B lists non-evaluated substances. These materials can be used in food packaging as long as transfer of these substances to food or food simulants is not detected. The detection limit cannot exceed 0.01 mg/kg (10 ppb). Nestlé Guidance Note on Packaging Inks (February 2014) is an initiative on packaging safety and compliance. The document applies to printing inks, lacquers, coatings and varnishes. As a rule, only ink ingredients listed on the Swiss ordinance list can be used, with the migration-maximum mentioned in the A list. For the B list, the detection limit cannot exceed 0.01 mg/kg (10 ppb). +

Raw Material Selection Strategies Photoinitators present migrating species in the cured product both as residual unreacted material as well as side products formed during the cure reaction. A structure commercially available that addresses both incorporation and elimination of odorous side products is an oligomeric polyfunctional α hydroxyketone photoinitiator. The oligomer is of high molecular weight compared to the standard monomeric α hydroxyketone photoinitiator. There are multiple photoreactive radical forming moieties per molecule. In addition, it can generate radicals both by α-cleavage with formation of the benzyl radical and by hydrogen transfer with the formation of a ketyl radical. The structure of oligomeric polyfunctional α hydroxyketone photoinitiator is shown in the Figure 1.

FIGURE 1. Structure of the oligomeric polyfunctional α hydroxyketone photoinitiator The attachment of the photoreactive species along the backbone prohibits the formation of aromatic aldehydic compounds during the cure reaction. In the FCN 722, the purified dimer, Esacure One, has been used to demonstrate radiation curing in a food contact application. Polymeric photoinitiators can also be based on linear structures where photoreactive moieties are attached to the end(s) of polymeric backbones. This type of structure gives rise to very viscous products that have low migration potential due to both their relatively high molecular weight and ability of the photoreactive ends to incorporate into the growing polymer, effectively crosslinking the photoinitiator in the network. A variety of linear high molecular weight polymeric photoinitiators (both Type I and Type II) are commercially available, along with amine synergists. These items together help to create a greater formulation latitude. page 16 u UV+EB Technology • Issue 2, 2016 | 15


PI moiety

Polymer Backbone

FIGURE 2. Schematic of linear polymer photoinitiator structure A common challenge in food packaging is the requirement for a coating to remain flexible in addition to limiting the migrating components. Outside of the migration requirement, formulations for flexibility include the use of monofunctional monomer. Partially reacted multifunctional monomers are chemically bound in the coating polymer matrix, while – due to their single reaction point – monofunctional monomers are chemically bound or are free to migrate after cure. For this reason, monofunctional monomers are typically excluded, even in low percentages, from low migration applications. However low migration strategies for highly functional monomers can reduce the coating flexibility through increased crosslink density and shrinkage upon curing. Use of ethoxylated and propoxylated versions of highly functional monomers can allow for greater flexibility while maintaining the

Absolute UV measurement in a flash

PI moiety

desired functionality. The greater molecular weight and nature of the group incorporated also can have beneficial impact to the migration and organoleptic properties.

Many of the acrylate monomers and oligomers in the industrial sector are produced using the standard solvent esterification process. This process uses toluene and/ or cyclohexane, and residual amounts of solvent are present in the final product. The residual content is typically at low levels (<5000 ppm), even for industrial uses. Materials recommended for low-migration applications undergo additional processing/ stripping steps to reduce the residual solvent to very low levels (<5 ppm). Radiation-cured inks and coatings provide a wide toolbox to the formulator to tailor the liquid formulation for application technique while maintaining the target cured properties as well. Selection of photoinitiators, monomers, oligomers and the curing radiation should work together to incorporate or confine the components in the coating after the cure process is completed. It is important for everyone in the value chain to remember that low-migration applications require a concerted strategy that includes the raw material selection as well as the ink formulation, cure conditions and intended product use environment. Guidelines and recommendations should be applied to each component of composite packaging materials. Migration data should be generated under realistic and practical conditions by accepted analytical methods, as the nature of substrates, packaging contents and converter operations conditions can be diverse. It is ultimately the responsibility of the packaging designer, the printer that manufactures the packaging and the distributor of the product to ensure that the packaging produced meets requirements of the regulations. Advice and guidance on selection of appropriate materials for the end use of the packaging is available from raw material suppliers and trade associations to help ensure compliance. u Acknowledgments: Tracey Norton and Graham Butterworth are kindly acknowledged for their contributions to the European regulatory references. Jennifer Walsh assisted in the preparation of this manuscript.

BTS2048-UV Spectroradiometer 16 | UV+EB Technology â&#x20AC;˘ Issue 2, 2016 +


Miwon Specialty Chemical Co., Ltd. is a world-class producer of specialty acrylate and methacrylate monomers and oligomers. Miwon maintains a global presence – in Asia, North America and Europe – with full-scale production facilities, regional technical support laboratories, regional customer sales/supply support offices and local warehouses. We are a key raw materials supplier to the inks, coatings, adhesives and electronics industries. As manufacturing raw materials for UV and EB curing is our core business, we offer one of the broadest product lines for formulators utilizing this advanced and environmentally friendly technology. Products are engineered to support changing market needs: • Cross contamination free • Toluene free (HAP free) • Consistency in quality • BPA-free systems • High purity • Low residuals • Low extractables • High refractive index • Tin-free oligomers • Captive EO/PO capability As a member of the American Chemistry Council, we are committed to the principles of Responsible Care. Miwon Specialty Chemical Co., Ltd. Miwon North America 696 W. Lincoln Highway Exton, PA 19341

Phone: 484-872-8711 Fax: 484-872-8717

SOFT-TOUCH COATINGS By Xavier Drujon, Lisa Spagnola, Gunter Moeller, Sartomer

Most Recent Developments in UV-Curable Soft-Touch Coatings S

oft-touch coatings are unique finishes that deliver the feel and appearance of a velvet or flocked fabric substrate. Tactile surface feel is one of the most sought-after features in plastics decoration. Thousands of neural receptors in our fingertips process touch differences as small as 1/300th of an inch. Touch can’t be turned off, and fingertip appeal plays an influential role in buying behavior. This is particularly the case for soft-touch coatings.

This was illustrated1 in a recent paper that demonstrated “.. there is evidence that integration of soft-touch coatings increases FMOT (First Moment Of Truth) and SMOT (Second Moment Of Truth) particularly in beauty and cosmetics” packaging as “customers are willing to pay a 5% price increase for packaging with soft-touch tactile coating as opposed to packaging with no tactile coatings.” The interest shown by brand owners in tactile surface feel encompasses all B to C markets, including packaging, consumer electronics, automotive, small appliances and aerospace. Beyond just adding a feeling of quality, brands can connect with consumers through touch, using emotional engagement and visceral reaction to manipulate the connection between perception and reality Conventional soft-touch coatings can provide excellent soft-touch properties. They are two-part isocyanatebased chemistries in either solvent or water that use a difunctional polyol with a trifunctional hardener (isocyanate). A large portion of the formulations used are solvent borne, with limited pot life and a requirement for an extended cure time. There is a clear interest in a UV-curable system that can replace current 2K soft-touch coating technology. In addition, there is a need for increased resistance to mars, abrasions, stains and chemicals compared to the conventional systems. Quantitative Assessment of Soft-Touch Coatings Quantitative assessment of soft-touch performance of a coating remains elusive. Various authors have reported a strong influence of parameters such as participant’s age2, sex3 or fingertip moisture level4 on tactile perception, just to name a few. In our studies, experimental soft-touch plate samples were evaluated by a panel of 11 people selected among our R&D and headquarters staff. They were selected to create a range of background, age and gender. The perception of touch is complex, and ways to describe the full tactile experience quantitatively are lacking. To start, we explored only one dimension, using the attribute “hard” (1) versus “soft” (5). Table 1 reports the results obtained for “sample 19.” TABLE 1. Evaluation of “soft-touch” plate sample 19 (hard=1 soft=5).

18 | UV+EB Technology • Issue 2, 2016 +

were acquired for each sample. Custom software written in IGOR® was used for data analysis to determine elastic and storage moduli and adhesion forces. A Poisson ratio of 0.4 was assumed to calculate shear storage and loss moduli from the AFM data. The data analysis is based on the adhesive contact model put forward by Daniel Maugis. 6

1 = Rubbery feel 2 = Velvety feel 3 = Silky feel

P adhesion FIGURE 1. Adhesion forces measured through AFM nanoindentation correlate very well with touch perception.

Figure 1: Adhesion forces measured through AFM nanoindentation correlate very well with touch We confirmed perception that perception of feel varies from person to We found that the adhesion forces measured through AFM

person: What feels “hard” to one person might feel “soft” nanoindentation correlate very well with touch perception. to another, and observers need to be trained to rate soft feel Average adhesion forces for two samples with a “silky” feel properly. We found that that using three test samples described were highest and approximately 10 times higher than for the two Soft-touch Properties and Cross-linking as “rubbery,” “silky” and “velvety” as a reference helped us to Density “rubbery” samples. Adhesion forces of the “velvety” samples establish a comprehensive “language” for our panel of volunteers. were approximately two to three times higher than those for the rubbery samples (Figure 1). While we currently do not understand 2000.perceive ContactitsAdhesion and Rupturethe ofchanges Elastic in Solids. Springeradhesion series in solidour state sciences When touching6 Maugis, a surface,D., humans topography the measured forces, results, Newa York: and softness by(Berlin slidingHeidelberg a fingertip, with certain Springer-Verlag) velocity and nevertheless, may be a first step in predicting touch feel based on pressure. The sensation of pleasantness or unpleasantness results, physical properties measurements. in part, from the frictional force and by the surface topography. We applied atomic force microscopy (AFM) to measure All AFM indentation measurements were performed with mechanical properties of coating surfaces with the goal of an MFP-3D atomic force microscope (AFM) from Oxford correlating results with touch feel. Instruments (formerly Asylum Research). HAS 60 AFM probes page 20 u +

UV+EB Technology • Issue 2, 2016 | 19

density was varied by adjusting the end chain acrylic functionality from 2 to 6 per molecule on average.


MEK resistance (s)

The resins (46,50%) were formulated with solvents (MEK and BuAc 23,25% each), photoinitiators (Irgacure 184 2,60%), matting additives (Acemat 3300 4%) and dispersant (Disperbyk 2008 0,4%). The formula was applied on glass panel 100 µm wet, dried 5 minutes at 55 to 60°C and cured 4x10m/min with a Fusion Hg lamp at 120W/cm. t page 19 from Team Nanotec® with a spring constant MEK resistance (s) and haptic feel as a function of of approximately 27 N/m and an end-radius double bond concentration (mol/g) in formula of approximately 60 nm was used for indenting the coatings. The spring constant 60 was determined using the Sader method5. 50 The probes were calibrated based on force distance curves acquired on a silicon 40 sample. 30

Nanoindentation of the coatings was performed in adhesive oscillatory contact. Force amplitudes of 100 nN or 200 nN 10 were used for the oscillatory loading measurements. The frequency was 1 Hz. 0 Data points were acquired for 60 seconds 0,00E+00 5,00E-04 1,00E-03 1,50E-03 2,00E-03 2,50E-03 for each curve. Six to ten curves without Double bond concentration (mol/g) obvious artifacts were acquired for each sample. Custom software written in IGOR® was used for data analysis to determine Soft Touch Coating elastic and storage moduli and adhesion Slippery Coating forces. A Poisson ratio of 0.4 was assumed to calculate shear storage and loss moduli FIGURE 2. Variation of MEK rub resistance and soft-touch properties with from the AFM data. The data analysis is double-bond concentration in a homogeneous series of aliphatic urethane based on the adhesive contact model put acrylates. forward by Daniel Maugis.6 Figure 2: Variation of MEK rub resistance and soft-touch properties with double-bond concentration in a homogeneous series of aliphatic urethane acrylatesSoft-touch Properties and Cross-linking Density To improve mar, abrasion, stain and chemical resistance, UV coating chemists usually rely first on increasing cross-linking density. 20

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We evaluated the haptic properties and the MEK rub resistance of a homogeneous series of aliphatic urethane acrylates (MW = 3000 g/mol) with identical soft polyol segment. Cross-linking density was varied by adjusting the end chain acrylic functionality from 2 to 6 per molecule on average (Figure 2). The resins (46,50%) were formulated with solvents (MEK and BuAc 23,25% each), photoinitiators (Irgacure 184 2,60%), matting additives (Acemat 3300 4%) and dispersant (Disperbyk 2008 0,4%). The formula was applied on glass panel 100 μm wet, dried 5 minutes at 55 to 60°C and cured 4x10m/min with a Fusion Hg lamp at 120W/cm. In first approximation, for weakly cross-linked soft materials such as the one chosen in this study, the cross-linking density of the film after cure can be considered as proportional to the doublebond concentration before cure.

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20 | UV+EB Technology • Issue 2, 2016

In any case, as the concentration of double bonds was increased, improvement of MEK resistance was concomitant with the disappearance of the soft-touch property. During our investigations, we observed that the same dependence held true for mar, abrasion, stain or chemical resistance in most homogeneous coating systems. page 22 u +

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Trifunctional cross-linkers will be called M1, M2, M3, M4, M5

The ratio of difunctional to trifunctional material was screened at 90:10 and 60:40.


The resins were formulated with solvents (50:50 MEK:BuAc 125 phr), photoinitiators (PL-HMPP 5phr), matting additives (Acemat 3300 8,5 phr) and dispersant (Disperbyk 2008 0,85 phr). The formula was applied on glass panel 100 µm wet, dried 5 minutes at 55 to 60°C and cured page 20with a Fusion Hg lamp at 120W/cm. t 4x10m/min

TABLE 2. Design of Experiment – formulation.

Table 2: Design of Experiment – formulation

The properties of selected DOE samples are compared with standard 2K PUR soft-touch coating in Figure 3. Formulations containing 60% difunctional material and 40% trifunctional material had the best properties, but these formulations were more rigid and had a silky versus rubbery feel. DMA showed “silky” samples to have a higher storage modulus (300-700 mPa vs 3-4 mPa) and two phases, one with a Tg well below room temperature (about -10 to -20°C) and a second Tg around 70 to 80°C.



solvent resistance

5 4.5 4 3.5 3 abrasion 2.5 2 1.5 1 0.5 0

solvent resistance



5 4.5 4 3.5 3 2.5 pencil 2 1.5 1 0.5 0


pencil hardness

2K 4 9 18

2K 4 9 18

stain resistance

stain resistance


Design of Experiments (DOE) We decided to screen blends of difunctional urethane acrylate “oligomers” with trifunctional urethane acrylate monomer “crosslinkers.” In the remainder of the text: • Difunctional urethane acrylates will be called UA1, UA2, UA3, UA4, UA5 • Trifunctional cross-linkers will be called M1, M2, M3, M4, M5 • The ratio of difunctional to trifunctional material was screened at 90:10 and 60:40. The resins were formulated with solvents (50:50 MEK:BuAc 125 phr), photoinitiators (PL-HMPP 5phr), matting additives (Acemat 3300 8,5 phr) and dispersant (Disperbyk 2008 0,85 phr). The formula was applied on glass panel 100 μm wet, dried 5 minutes at 55 to 60°C and cured 4x10m/min with a Fusion Hg lamp at 120W/cm (Table 2). The properties of selected DOE samples are compared with standard 2K PUR soft-touch coating in Figure 3. Formulations containing 60% difunctional material and 40% trifunctional material had the best properties, but these formulations were more rigid and had a silky versus rubbery feel. DMA showed “silky” samples to have a higher storage modulus (300-700 mPa vs 3-4 mPa) and two phases, one with a Tg well below room temperature (about -10 to -20°C) and a second Tg around 70 to 80°C.

FIGURE 3. Properties of selected DOE samples – first series.

Based on the first set of experiments, the Design of Experiments was extended to screen combinations of cross-linker M1 with oligomers UA4 and UA5.

3: Properties of selected samples – first series Figure 3: PropertiesFigure of selected DOE samples – firstDOE series

22 | UV+EB Technology • Issue 2, 2016 +

Based on the first set of experiments, the Design of Experiments was extended to screen combinations of cross-linker M1 with oligomers UA4 and UA5.

TABLE 3. Properties of selected DOE samples – second series.

Finally, the combination of UV technology with 3D decorative processes – such as screen or inkjet printing – will create new possibilities in terms of 3D tactile finishes. u References

1. Colleen Twomey, from Cal. Poly. Univ., (Radtech USA 2015) 2. The effect of age on neural processing of pleasant soft touch stimuli. A. May et al., Frontiers in Behavioral Neuroscience (2014) Table 4: Properties of selected DOE samples – second series 3. Quantitative assessment of pleasant touch. G. Essick et al., The combination of UA5 60% and M1 40% provides a UV Neurosciences and Biobehavioral Reviews 34 (2010) 192-203 system that has good feel with increased mar, abrasion, stain, and 4. increased Rash built model of pleasant touch through active fingerprint The combination of UA5 60% and M1 40% provides a UV system that has good feel with chemical resistance compared to the conventional systems. exploration. Klocker et al. (2012) Front Neurorobot 6: 1-9 mar, abrasion, stain, and chemical resistance compared to the conventional systems. 5. Sader, J.E.; Larson, I.; Mulvaney, P.; White, L.R. Rev. Sci. Inst., Conclusions 1995, 66, 3789 This work demonstrates the possibility of formulating solventSader, J.E.; Chon, J.W.M.; Mulvaney, P. Rev. Sci. Inst., 1999, 70, Conclusions based UV systems with good feel and increased mar, abrasion, 3967 This work demonstrates possibilitycompared of formulating UV systems with good feel and J.E.; Encyclopedia of Surface and Colloid Science, 2002, stain, and chemical the resistance to solvent-based the conventional Sader, increased abrasion, stain, and chemical resistance compared to the conventional 2K-PUR 2K-PURmar, systems. 846-856 systems. 6. Maugis, D., 2000. Contact Adhesion and Rupture of Elastic Solids. Springer series in solid state sciences (Berlin Heidelberg New York: Ongoing work in our laboratories on 100% UV-curable and Springer-Verlag) waterborne UV-PUD soft-touch coatings will further expand the Ongoing work in our laboratories on 100% UV-curable and waterborne UV-PUD soft-touch coatings possibilities for the formulators. will further expand possibilities for formulators.

Finally, the combination of UV technology with 3D decorative processes — such as screen or inkjet printing — will create new possibilities in terms of 3D tactile finishes.


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UV+EB Technology • Issue 2, 2016 | 23

Industry News Lisa Fine Honored by NAPIM The National Association of Printing Ink Manufacturers (NAPIM), Peachtree Corners, Georgia, honored Lisa Fine, technical director for Joules Angstrom U.V. Printing Inks, with its Ault Award during the 101st annual NAPIM Convention. The Ault Award, which has traditionally been the highest award that members of the ink industry can bestow on one of their peers, was established in memory of L.A. Ault, an early leader in the industry and a founder of the Ault and Wiborg Company. Each year nominations are sought from all U.S. and Canadian ink manufacturers for submission to a special awards committee, which makes the final selection. Fine is the president-elect of RadTech. She began her career in 1989 as a chemist for WR Grace. After serving as a technical service manager at Cabot Corporation, Fine founded Flexo Tech, Inc., a consulting organization that provides laboratory services, formulation development and training to the ink industry, focusing on water-based and UV-based inks. Fine is the holder of eight patents, and has been a technical advisor to Ink World magazine since its inception. In addition, NAPIM presented seven Printing Ink Pioneer Awards during the ceremony. The honorees include Michael Keegan, VP of sales, Paste Ink Division, Toyo Ink America; Joe Kelly, R&D director of liquid water-based inks, INX International; Robert Lu, COO, Ink Systems; Suresh Mahajan, president, Modern Printing Colors; Pete Notti, VP, Ink Systems; Tom Rogers, retired president and CEO, Apollo Colors; and Greg Yoder, business director pressroom chemicals, Flint Group. For more information, visit Flint Group Issues Binding Offer to Siegwerk Flint Group, headquartered in Luxembourg, announced that it has issued a binding offer to Siegwerk Druckfarben, Siegburg, Germany, to acquire its web offset business. This offer includes the transfer of all technical expertise and product portfolios relating to Siegwerk’s Heatset and Newsink product lines. This acquisition will provide both companies the opportunity to focus on and continue to build their individual markets. For more information, visit or Dymax Announces Suzuki, Shaskey Appointments Dymax Corporation, Torrington, Connecticut, is pleased to announce the appointments of Steven Suzuki as global account manager for the Western Region and David Shaskey as territory sales manager. Suzuki will report to Stephen LaCroce, managing director of North America, and will be responsible for the achievement of sales growth and coordination of all support activities and projects at Dymax’s Strategic Global Accounts, both directly and through Dymax personnel worldwide. Shaskey 24 | UV+EB Technology • Issue 2, 2016

will report to Mike Acker, Americas sales manager, and will provide a key service in helping manufacturers in the Minneapolis region solve complex application problems and reduce manufacturing costs. For more information, visit Sartomer Americas Announces New Director of R&D Sartomer Americas, Exton, Pennsylvania, has named Dr. Jeffrey Klang director of research and development. Klang will lead R&D programs to support development and growth of high-value applications and technologies within Sartomer’s key end-use markets, including coatings, graphic arts, adhesives, sealants, elastomers, electronics and 3D printing. He also will ensure Sartomer’s R&D efforts continue to align with current customer, market and regulatory needs. For more information, visit Tribogenics Taps Electron Beam Engineering for High Precision Welding Electron Beam Engineering, Inc. (EBE), Anaheim, California, has been chosen to be supplier of record for the $20 billion X-ray industry’s first triboluminescencebased handheld XRF analyzers launched recently by Los Angeles-based X-ray pioneer, Tribogenics. EBE reviewed and improved Tribogenics’ manufacturing processes. Tribogenics adopted the recommendations and improved the manufacturability of the new Watson handheld analyzers. As a result, test times have been cut in half. For more information visit or Anthony Bean Receives TAGA Award Anthony Bean of Sun Chemical, Parsippany, New Jersey, has been honored by the Technical Association of the Graphic Arts (TAGA) as a recipient of the prestigious Michael H. Bruno Award. The board of directors of TAGA singles out professionals with distinguished careers to receive the TAGA Michael H. Bruno Award in appreciation for their dedicated service and contributions to the advancement of graphic arts internationally. Bean, a field marketing manager of energy curing, first joined Sun Chemical in 1969 and has held various positions that cover all phases of the inks group at Sun Chemical, including R&D, +

manufacturing, technical support, sales and marketing. He holds three patents in energy curing, is the author of four published books and is the writer of many articles on ink technology and energy curing. Bean has served on the board of directors for RadTech International, spoken at numerous conferences, instructed many courses for the Oil & Color Chemists Association and the National Association of Printing Ink Manufacturers (NAPIM), and has been the recipient of the NAPIM Printing Ink Pioneering Award and NAPIM Technical Achievement Award. He holds an M.B.A. and a master’s degree in chemistry from Fairleigh Dickinson University in Rutherford, N.J. and a bachelor’s degree in chemistry from Loras College in Dubuque, Iowa. For more information, visit AkzoNobel to Acquire BASF’s Industrial Coatings AkzoNobel has made an agreed offer to acquire BASF’s Industrial Coatings business. The transaction would include technologies, patents and trademarks, as well as securing supply to customers worldwide. Two manufacturing plants – one in the UK and one in South Africa – also would be transferred to AkzoNobel. The business supplies products for a number of end uses, including coil, furniture foil and panel coatings, wind energy and general industry, and commercial transport. The planned transaction is expected to be completed in the second half of 2016, subject to regular consultation with employee representatives and satisfaction of certain closing conditions, including receipt of required regulatory approval. For more information, visit Evonik and Jungbecker Form Partnership Evonik Cyro LLC, Parsippany, New Jersey, will be the exclusive sales agent in the North America region for global optical elements supplier Jungbecker. Jungbecker’s offerings will expand Evonik’s lighting portfolio and include access to precision optics and Custom optic custom solutions for diffusion, demicrostructures glaring and light guide applications, allowing for greater flexibility to adapt with light emitting diode (LED) technology and changing design specifications. This, combined with high-quality polymethylmethacrylate (PMMA) material solution offered by Evonik, creates a “one-piece” acrylic-based, light-shaping lens solution for customers. For more information, visit

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Environmental Inks Announces Rebranding Environmental Inks, Morganton, North Carolina, announced that it will be rebranding to align the organization’s image with Siegwerk’s global strategy throughout 2016. Environmental Inks will begin operating under the new brand of Siegwerk Environmental Inks. The rebrand is the outcome of the company’s continued growth and brand recognition. For more information, visit page 26 u +

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Think UV. Think Heraeus. UV+EB Technology • Issue 2, 2016 | 25

Industry News Miltec Adds New Employees and Positions Miltec UV, Stevensville, Maryland, announces the appointments of Bill Zlakowski, Ian Smith, Nan Jiang and Tom Frobish. Zlakowski joined Miltec in December 2015 in the role of purchasing manager. Smith joined Miltec in March in the role of Zlakowski Smith electronics engineering technician. In this position, he will support Miltec’s engineering, manufacturing and service departments. Jiang joined Miltec in March as the director of sales – Asia. In this new position, he will be responsible for the horizontal growth of Miltec’s Jiang Frobish Asian market, expanding the geographical reach of products and services. Miltec recently promoted Frobish into the new role of industrial designer. For more information, visit

sq. ft. is double the size of the previous facility. This now allows new capabilities for research, development and manufacturing. With this January 2016 relocation, CPS is better able to support customer needs for custom formulation development and manufacturing. For more information, visit Deivis Parejo Joins Honle UV America Deivis Parejo has joined HONLE UV AMERICA, INC. in a business development position. Parejo will lead HONLE’s UV/ LED equipment business and is motivated by the opportunities to deliver UV/LED experiences to worldwide integrators and contract manufacturers large and small. Prior to joining HONLE UV America, Parejo served as a Latin America International regional sales manager and as a project solution specialist for Engineered Products. Parejo holds a Bachelors in Mechanical Engineering from University of Massachusetts at Lowell and an Associates in Engineering Design from Massachusetts Bay College. For more information, visit u

CPS Grows into New Facility Colorado Photopolymer Solutions (CPS) is pleased to announce its expansion into a new facility located in Boulder, Colorado. The new combination of lab, manufacturing and office space at 7,000

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PROPERTY MONITORING By Parag K. Shah, Department of Chemical and Biological Engineering, University of Colorado Boulder and Jeffrey W. Stansbury, Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Denver

Simultaneous Monitoring of Property Development and Reactive Group Conversion in Photopolymer Systems T

he performance of materials in the UV industry for applications such as coatings, adhesives, dental materials and 3D printing depends on the ultimate properties of these materials. The properties are, in turn, dependent on the formulation and processing conditions that lead to the final product from the starting materials. A typical photopolymer formulation consists of a monomer mixture, photoinitiator(s), pigments, particles and other additives. The monomers can be of different types depending on the curing chemistries utilized to polymerize them [1]. The geometry and cure conditions also affect the processing of the material due to differences in kinetics and the exothermic reaction. Ultimately, however, the final properties for a particular system are significantly determined by the extent of cure, other variables being held constant [2â&#x20AC;&#x201C;5]. Measurement of functional group conversion is important in determining performance under a given set of conditions. Polymerization is accompanied by volumetric contraction and the subsequent development of shrinkage stress in hard polymers, which can be detrimental to performance. Shrinkage is more or less linearly dependent on conversion, but properties such as modulus and shrinkage stress are nonlinear. All these properties can be tied together with the measurement of conversion. This means it is important to measure the conversion and also to monitor the dynamic progress of conversion to more accurately gain information about the network development. An often overlooked factor, especially for thin films, is the volatility of the photoinitiator. Previous work in our lab has shown that photoinitiators, especially camphorquinone that is widely used in visible light curing, can volatilize from the surface of the monomer film. This is especially critical in conditions that require purging to remove solvent, as with in dental adhesives [6]. This loss of photoinitiator can lead to a gradient in conversion with lower conversion at the surface, even in the absence of oxygen inhibition. This can significantly affect the reliability and performance of such materials. Fourier transform infrared spectroscopy (FTIR) can be used to quantitatively measure conversion for a wide variety of functional groups. Mid-IR spectroscopy spans the wavelength region of about 2500 to 25000 nm and is widely used. It contains the fundamental absorbance bands for a variety of functional groups, including the carbon-carbon double bond in acrylate and methacrylate monomers.

28 | UV+EB Technology â&#x20AC;˘ Issue 2, 2016 +

FIGURE 1. Instrumentation for measuring shrinkage, shrinkage stress and flexural modulus, coupled with conversion measurements. (a)



FIGURE 2. Variation of (a) shrinkage, (b) flexural modulus and (c) shrinkage stress with conversion and particulate filler loading. Lines connecting data points are provided for visual assistance. (Taken with permission from [8]) In general, the absorbance of different functional groups in the mid-IR spectral region is very high, restricting the measurement to very thin samples. In addition, many of the fundamental absorption bands from some of the functional groups can overlap in the fingerprint region, making it difficult to accurately assess conversion. Some of these issues can be overcome by using the near-IR spectral region that spans 2500 to 800 nm, which consists of overtone and combination bands of the fundamental absorbances. The absorptivity in the near-infrared FIGURE 3. Schematic of DMA connected to FT-IR and a light source. (NIR) region is much lower than in the mid-IR, (Taken with permission from [10]) which makes this region amenable to measurement of thicker samples than in mid-IR [7]. NIR signals also can be transmitted efficiently via fiber optics and utilized in enables the coordinated measurement of material properties along unpurged environments, making it convenient to analyze samples with conversion measurements, providing valuable insights into at locations away from the FT-IR instrument and to conduct other differences among materials and processing conditions while measurements simultaneously with FT-IR measurements. This helping to make informed decisions on their utility. page 30 u +

UV+EB Technology â&#x20AC;˘ Issue 2, 2016 | 29

PROPERTY MONITORING t page 29 are measured and indexed with conversion measurement, they can be compared with each other – even though the measurements are performed in different instruments and with different sample geometries. A model dimethacrylate resin formulation consisting of 2,2-bis[4-(2-hydroxy-3methacrylyloxypropoxy) FIGURE 4. Modulus evolution with respect to (a) time and (b) conversion for different irradiation phenyl] propane times and irradiances. (Taken with permission from [10]) (BisGMA) and triethylene glycol dimethacrylate (TEGDMA) (70/30 wt/wt ratio) was As an example of monitoring shrinkage, modulus and shrinkage used and 0.7 µm glass particles surface functionalized with a stress along with conversion, we have studied a system of model methacrylate silane were mixed with the resin at various loading dental composites with varying degrees of filler loading [8]. levels (0, 20, 40, 60 and 70 wt%). Shrinkage stress was measured Differences in the aluminosilicate glass loading level significantly using a tensometer, a cantilever-based instrument (Figure 1). affect conversion and, with the plethora of commercial dental NIR measurements of double bond conversion were done using restorative materials that have a wide variety of particle loading fiber optic cables connected to an FT-IR spectrometer. This levels, it is important to be able to predict the influence of the allowed real-time simultaneous measurement of shrinkage stress particulate filler on performance that is highly dependent on and methacrylate conversion. Flexural measurements were done conversion. This study helped to show how, when properties on rectangular specimens (2x2x10 mm), and shrinkage was measured with a linometer using disc-shaped specimens (1mm thickness, 6 mm diameter). The incident irradiance was kept the same for all the measurements. For the flexure samples, it was not possible to measure real-time IR using the fiber optic cables due to limitations in aligning them with the sample geometry. For the shrinkage samples, the NIR cables being used were of a small diameter (100 µm) and were not sufficient for a signal to pass through the highly filled samples. Figure 2 shows the results of the different measurements as a function of double bond conversion.


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Quite a few salient features can be extracted out of studying the property development in this manner. Shrinkage is fairly linear with respect to conversion for most of the range but tends to slow as the limiting conversion is reached [Figure 2(a)]. The deceleration of shrinkage is observed when the samples start to vitrify. While most of the sample is in a glassy state, there remain pockets of uncured monomers and pendant methacrylate groups that can still undergo polymerization, contributing to the increase in conversion while the shrinkage development is restricted by the glassy network. Flexural modulus develops exponentially with respect to conversion. At the same value of conversion, flexural modulus increases with particle loading, but the rate of increase is more pronounced when particle loading increases to more than 60 wt%. At these higher loadings, interparticle interactions increase, leading to the faster increase in modulus. Shrinkage stress followed a similar pattern to the modulus in varying with respect to conversion. At high conversion levels, page 32 u +


PROPERTY MONITORING t page 30 it is observed that – for the same irradiation conditions – as particle loading increases from the unfilled resin, the shrinkage stress decreases initially, possibly attributable to the reduction in shrinkage due to the reduced resin volume and also lower final conversion.

Lower conversion in highly filled composites can be caused by a variety of factors. Light is attenuated with increasing thickness due to scattering and absorption by the particular fillers that generally have a different refractive index as compared to the resin mixture [9]. These particulate fillers act as a heat sink, reducing the overall exotherm, which also adversely affects conversion. Surface-bound methacrylate silanes provide a mobility-restricted environment at the interface between filler particles and the resin matrix, which also likely contributes to a reduced conversion. After going through a minimum at about 40 wt% particle loading, the shrinkage stress increases again, in spite of the lower conversion. This can be attributed to the contribution from higher particle loading to the modulus. Measurement of conversion, along with following the evolution of material properties, can lead FIGURE 5. Rheometer setup for simultaneous measurement of shear moduli and to significant insights into functional group conversion. the interplay of the various (a)



FIGURE 6. BisGMA/TEGDMA series (a) real time storage modulus, (b) real time methacrylate conversion and (c) storage modulus with respect to conversion. (a)



FIGURE 7. BisGA/TEGDA series (a) real time storage modulus, (b) real time methacrylate conversion and (c) storage modulus with respect to conversion. 32 | UV+EB Technology • Issue 2, 2016 +

properties, thus helping to optimize the curing process depending on the final application. Modulus also can be related to real-time conversion by directly coupling a DMA with NIR fiber optics. Figure 3 represents the schematic of achieving this in a light-accessible DMA (Perkin Elmer 8000). This study examined the effect of irradiance and irradiation times on the modulus development during dark cure [10]. Samples (BisGMA/TEGDMA at 70:30 wt/wt ratio) were partially cured to about 30 to 40% conversion to achieve reasonable stiffness so that they could be held in the single cantilever accessory in the DMA. They were then aligned with the NIR fiber optic cables and also a UV light source (365 nm). Samples were further cured for various times at a low irradiance or at high irradiance in the DMA while flexural modulus was measured, along with conversion (Figure 4). Figure 4(a) shows the modulus as a function of time and Figure 4(b) shows the modulus as a function of conversion. At the low irradiance level with short irradiation times, there is significant amount of dark cure but only modest increase in the modulus. The more extensive dark cure can be attributed to the higher mobility of radicals at the lower modulus. At higher irradiation times, the vitrification stage is reached and there is significant rise in the modulus with very little amount of dark cure, this time due to the very mobility of the radicals and reactive sites in the network. At the higher irradiance level, the modulus increase is much higher than the corresponding low intensity sample, and the limiting conversion is also increased. This is due to the greater exotherm attributable to the higher irradiance used for curing, which increases the mobility of the network and subsequently delays the vitrification. The increased conversion further raises the final modulus of the network. This study points to the need for monitoring temperature during polymerization and studying the effect of irradiance and irradiation times to optimize the final properties of the network. Photorheometry is an important tool to characterize viscoelastic properties of monomers and polymeric materials. We have connected NIR fiber optics to a photorheometer to monitor real-time conversion and shear moduli at the same time (Figure 5). This technique also helps to locate the crossover point between the shear storage and loss moduli that can be taken as an indication of the gel point of the network. In this study, mixtures of BisGMA/TEGDMA (70/30 wt/wt) and 2,2-bis[4-(2hydroxy-3-acrylyloxypropoxy)phenyl] propane/triethylene glycol diacrylate (BisGA/TEGDA -70/30 wt/wt) were studied separately to determine differences in modulus development with respect to conversion. Figure 6 shows that the BisGMA/TEGDMA combination displays slower kinetics than the BisGA/TEGDA mixture, as expected (Figure 7). The modulus development shows a faster rise in the modulus of the BisGMA/TEGDMA mixture. When the modulus is plotted with respect to conversion, it is apparent that the vitrification point for the methacrylate mixture is reached earlier than that for the acrylate mixture. This is page 34 u +

UV+EB Technology â&#x20AC;˘ Issue 2, 2016 | 33



FIGURE 8. UV-Vis/FT-IR setup for simultaneous measurement of absorbance and conversion. (Taken with permission from [11])


(b) FIGURE 9. (a) Fractional vinyl conversion and camphorquinone consumption as a function of irradiance; (b) monomer polymerization rate and camphorquinone consumption for different amine reductants and (c) quantum yield of CQ reduction as a function of vinyl conversion for different amine reductants. (Taken with permission from [11])

(c) 34 | UV+EB Technology â&#x20AC;˘ Issue 2, 2016 +

expected, as the methacrylate polymerization results in a much stiffer network than that formed with the acrylate polymerization at ambient curing conditions. This study confirms existing knowledge, and the technique is powerful when there is a need to test new monomers to elucidate the way the polymer network and its properties develop in real time to enable better design of novel monomers. Photoinitiators are critical components of a photopolymerization system. It is important to use a photoinitiator that matches with the light source being used and also to ensure compatibility with the monomer chemistries. The photoinitiator being used should have high quantum yield and efficiency. Studies of photoinitators generally are done using UV-Vis and in solvent or at very low concentrations in a monomer. This is not optimal, as the behavior of the photoinitiator depends on its environment and may differ in going from the solvent to the monomer. Monitoring of the photoinitiator during a polymerization brings along its own set of challenges, such as having to prevent curing of the resin formulation by the UV-Vis source and ensuring that the polymerizing light source does not interfere with the UV-Vis signal. It becomes necessary to use a very low intensity for the UV-Vis source to be able avoid polymerizing the sample, leading

to loss in sensitivity of measurement. Separate measurements of UV-Vis and FT-IR have been done previously, but the ability to reproduce the exact irradiation and polymerization conditions when testing a sample in two different experiments is unreliable, leading to possible misrepresentation of data. Figure 8 shows the setup in which UV-Vis and NIR cables are placed orthogonal to each other and in the same plane in front of a cuvette containing the solution to be tested. This avoids issues related to making separate measurements. The light source for photopolymerization is placed directly above the cuvette. As an example, ethoxylated bisphenol-A dimethacrylate (BisEMA) was mixed with camphorquinone, and the effect of using different amine reductants was tested using this coupled UV-Vis/FT-IR system [11]. The amine reductants tested were ethyl 4-(dimethylamino)benzoate (EDMAB), methyldiethanolamine (MDEA) and N-phenylglycine (PG). Figure 9(a) shows the effect of different irradiances on polymerization and the simultaneous photobleaching of CQ, demonstrating that it is possible to track both processes at the same time. The effect of using the different amine reductants on polymerization rate can be seen in Figure 9(b). Quantum yields for CQ using the different amine reductants with the overlapping page 36 u

Alberdingk Water-based UV-Curable Dispersions for Industrial Coatings With a legacy of more than 185 years in castor and linseed oils, driven by tradition and innovative technology, Alberdingk Boley is a proud, responsive supplier of environmentally friendly water-based emulsions and polyurethane dispersions to the paint and coatings, adhesives, and graphic arts industries. Alberdingk Boley offers a full line of waterborne emulsions and polyurethane dispersions including UV-curable dispersions for wood, metal, concrete, plastics, glass, and ďŹ&#x201A;exible substrates (leather/synthetic leather, textiles, paper, and plastic ďŹ lms).

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UV+EB Technology â&#x20AC;˘ Issue 2, 2016 | 35

PROPERTY MONITORING t page 35 conversion can be seen in Figure 9(c), showing the reduction in quantum yield as the system gets stiffer and vitrifies. Key parameters related to the photopolymerization process can be calculated using such experiments (data not shown). In conclusion, we have briefly shown a variety of setups in which FT-IR instruments can be coupled to other instruments that measure properties such as shrinkage, shrinkage stress, flexural modulus, complex moduli and UV-Vis spectra. Combining each of these property measurements becomes possible due to the simultaneous measurement of conversion, which can be used as an indexing parameter for a given system. These studies can help evaluate monomers for particular applications and also test irradiation conditions to be used to get the correct match of mechanical properties for the final application. u Parag Shah received his Bachelor’s and Master’s degrees in chemical engineering from the Indian Institute of Technology Bombay. He then moved to University of Colorado at Boulder to complete his PhD in chemical engineering. His PhD thesis work under Dr. Stansbury involved surface modification of nanoparticles using polymer brushes for shrinkage stress reduction in dental restorative materials. After receiving his PhD degree, Shah decided to continue working in the Stansbury lab as a post-doctoral research associate, where he is currently working on developing polymer nanoparticles for various applications and developing techniques to study the fundamentals behind the effect of these nanoparticles. His research interests include photopolymerization, surface science and nanocomposite applications. Jeffery Stansbury received his undergraduate degree in chemistry from the University of Maryland, followed by a position in the Polymers Division at the National Institute of Standards and Technology (NIST). He returned to University of Maryland in College Park for graduate school in organic/polymer chemistry while continuing at NIST. His PhD thesis work involved free radical and cationic ring-opening polymerizations under William Bailey (graduated 1988). He remained at NIST a total of 21 years, working on a wide variety of polymeric biomaterials and materials characterization techniques. Stansbury then moved to the University of Colorado in 2000 to join the School of Dental Medicine to develop a biomaterials program there while also being appointed in the Department of Chemical and Biological Engineering in Boulder. In the dental school, he serves as vicechair of the Department of Craniofacial Biology and senior associate dean for research. He has research laboratories on both the Boulder and Anschutz Medical Campuses with work focused on a variety of fundamental and applied areas involving dental materials, polymer networks, photopolymerization and bioengineering. He has been the recipient of the bronze medal award from the US Department of Commerce, the Souder Distinguished Scientist award from the International Association for Dental Research (IADR) and the New Inventor of the Year 36 | UV+EB Technology • Issue 2, 2016

Award from the University of Colorado. He currently is president of the Dental Materials Group at IADR. References: [1] Carioscia JA, Stansbury JW, Bowman CN. Evaluation and Control of Thiol-ene/Thiol-epoxy Hybrid Networks. Polymer (Guildf) 2007;48:1526–32. [2] Howard B, Wilson ND, Newman SM, Pfeifer CS, Stansbury JW. Relationships between conversion, temperature and optical properties during composite photopolymerization. Acta Biomater 2010;6:2053–9. [3] Lovell LG, Lu H, Elliott JE, Stansbury JW, Bowman CN. The effect of cure rate on the mechanical properties of dental resins. Dent Mater 2001;17:504–11. [4] Stansbury JW. Dimethacrylate network formation and polymer property evolution as determined by the selection of monomers and curing conditions. Dent Mater 2012;28:13–22. [5] Stansbury JW, Trujillo-Lemon M, Lu H, Ding X, Lin Y, Ge J. Conversion-dependent shrinkage stress and strain in dental resins and composites. Dent Mater 2005;21:56–67. [6] Forman DL, McLeod RR, Shah PK, Stansbury JW. Evaporation of low-volatility components in polymeric dental resins. Dent Mater 2015;31:1090–9. [7] Stansbury JW, Dickens SH. Determination of double bond conversion in dental resins by near infrared spectroscopy. Dent Mater 2001;17:71–9. [8] Shah PK, Stansbury JW. Role of filler and functional group conversion in the evolution of properties in polymeric dental restoratives. Dent Mater 2014;30:586–93. [9] Emami N, Sjödahl M, Söderholm K-JM. How filler properties, filler fraction, sample thickness and light source affect light attenuation in particulate filled resin composites. Dent Mater 2005;21:721–30. [10] Abu-elenain DA, Lewis SH, Stansbury JW. Property evolution during vitrification of dimethacrylate photopolymer networks. Dent Mater 2013;29:1173–81. [11] Aguirre-Soto A, Hwang AT, Glugla D, Wydra JW, McLeod RR, Bowman CN, et al. Coupled UV-Vis/FT-NIR Spectroscopy for Kinetic Analysis of Multiple Reaction Steps in Polymerizations. Macromolecules 2015;48:6781–90. +

page 38 u

COATINGS By Richard W. Baird, senior chemical engineer and project manager, The Boeing Company

Heat-Resistant, UV-Curable Clearcoat for Aircraft Exteriors Abstract e are assessing the feasibility of developing and implementing a heat-resistant, UV-curable clear paint, or clearcoat, for use on the aircraft exterior. The clearcoat would protect underlying paint from discoloration experienced in service, thus improving its appearance and engineering performance. Nonpigmented urethane-based sample submissions were tested to our requirements for finish quality and engineering performance, with results approaching those of qualified thermally cured exterior urethanes. Pathways were identified for development and deployment of the clearcoat in production. Heat-soak testing of several rounds of clearcoat formulations from two suppliers showed substantially improved heat resistance compared to a thermally cured clearcoat used as a control.


Summary: Potential opportunities were identified for using very-fast-curing exterior aircraft paints for the purpose of reducing paint process cycle time and improving finish quality and durability for the airline customer. We determined that significant benefit would be realized with ultraviolet-curable (UV-curable) pigmented and clear paints when applied to areas requiring special-purpose coatings and when these coatings would impose unacceptable delays to the process flow unless their cure time was very short. An example of such an application is an identified need for heat-resistant coatings for exhaust vent areas, which is the subject of this article. A list of engineering and appearance requirements for this heat-resistant coating was generated, including the level of heat resistance deemed to be necessary to justify its use. These requirements are based on those for presently qualified exterior paints and include additional requirements specific to this special application. Two formulators were identified as having the resources and motivation to develop UV-curable clearcoats for aircraft exterior use. To facilitate the development process, a close collaboration was set up among these formulators, their raw material suppliers and the UV-cure equipment suppliers. A gated development path, leading ultimately to use of the UV-curable clearcoat in production, was established. At each development step the business caseTypical for proceeding to the next phase is assessed before Fig. 1: discoloration pattern (shown tocontinuing. relative scale)

Louvered vent opening Original paint color is white in this depiction

Air stream FIGURE 1. Typical discoloration pattern (shown to relative scale) 38 | UV+EB Technology â&#x20AC;˘ Issue 2, 2016 +

ready for flight at that point, while the thermally cured paint requires further cure to be ready for flight. Additionally, since UV cure can be accomplished without heating the paint hangar, other work can progress while paint is curing, unlike the case for thermally cured paint. UVcurable paints have the added benefit of helping reduce emissions of volatile organic compounds (VOCs), since they are typically formulated with up to 100% solids. (In a “100% solids” paint formulation, all of the paint material that reaches the part remains behind to dry, with no evaporative loss. This includes the reactive diluent in UV-curable formulations.) Requirements for a UV-curable, heatresistant exterior clearcoat. A number of requirements must be satisfied in order to achieve the most benefit from use of a UV-curable, heat-resistant exterior clearcoat. Together they present a significant formulation and processintegration challenge similar to that faced by the automotive industry, but with several added challenges unique to commercial airplane finishing. The heat-resistance requirement for the clearcoat is presently under development.

Photo copyright © Boeing

We recently completed several rounds of testing, reformulation and retesting of clearcoat formulas from these two suppliers. The latest formulations are close to satisfying the basic engineering requirements, with only minor adjustments required to fully satisfy these requirements. Efforts by the formulators to enhance the heat resistance of these formulas have resulted in a substantial improvement over the thermally cured clearcoat tested as a control. The problem to be addressed: Heat-induced discoloration of paint near utility exhaust vents. The clearcoats under development in this work have been evaluated for their ability to mitigate yellowing of the thermally cured urethane paints applied to the exterior downstream of small exhaust vents on the underside of the airplane. Fig. 1 is a schematic depiction of an exhaust vent and the region downstream most affected by heat. These paints are exposed to temperatures as high as 150°C (302°F) for extended periods in service. Over a period of months, severe discoloration (yellowing and browning) has been observed to occur. Applying an overcoating with the appropriate formulation would limit access of atmospheric oxygen to this paint, thus slowing the yellowing process. The clearcoat must have a very fast cure to minimize paint process flow impact due to the addition of steps for masking, application and cure of the clearcoat, hence the emphasis on UV-cured formulations. The total area needing protection is relatively small (<5 sq m or <50 sq ft) so it is anticipated that off-the-shelf curing systems designed for automotive aftermarket decoration may be adaptable to this application. At least one such system has been made available with explosion-proof upgrades to meet NFPA Article 500, Class I, Division 1 fire codes (required in our paint shops). Why UV cure? Drivers for using UV-curable exterior aircraft paints. The best opportunity for reducing paint process flow time is in the curing step. While the fastest thermally curable formulas require hours to reach a “dry-to-mask” condition, UVcurable paints achieve full cure in seconds. Moreover, they are +

The requirements include: •

Spray properties close to those of thermally curable paints. For optimum finish quality and shop-friendliness, the paint must have a spraying viscosity similar to that of thermally curable formulas and similar “leveling” power (ability to form a smooth film) and resistance to runs and sags. The closer the spray behavior is to that of conventional paint, the faster the learning curve will be for the painters. Reworks will be minimized. A typical approach is to formulate the paint with high room-temperature viscosity, and then heat the paint to lower the viscosity to a sprayable range. Leveling and sag resistance are then controlled by the rate of viscosity recovery as the paint film cools on the surface.

“Hang time” requirement. The room-temperature viscosity must be high enough to support a film about 0.002" in thickness (for adequate protection of underlying paint), applied in a single coat on a vertical surface for a period long enough to allow time to return to the wet film with the curing lamps. Use of thixotrope additives is typically needed to extend the “hang time” to an acceptable length while retaining good leveling. Without these additives the paint would either (1) continue to “level” slowly, finally developing sags after an interval typically too short to allow time to return with the cure system, or (2) level incompletely, leaving an unacceptably rough, “orange-peely” finish. page 40 u UV+EB Technology • Issue 2, 2016 | 39

COATINGS Fig. 2: Heat Soak Delta-E vs Temp after 60 days Thermally Cured Color HeatResults: Soak Results: Delta-E vs Temp after 60 days

delta-E after 60 days

t page 39 Coat + Clearcoats Thermally-Cured Basecoat + Clearcoats • Cure process 70 requirements. Equipment LOWER delta-E is BETTER BC-CC complexity, 60 weight, cost Best to date is “UV-B” CC (red curve) and power 50 consumption Goal is to be equal or less than BC (dark blue curve) must be UV-A minimized. 40 Ozone BC = Thermally cured Color Coat w/o Clearcoat generation must UV-B UV-A = UV-cured Clearcoat from A applied to BC 30 be minimized UV-B = UV-cured Clearcoat from B applied to BC BC-CC = Thermally cured Color Coat and Clearcoat or prevented to obtain the 20 maximum BC environmental 10 benefit. The equipment must be safe to use, 0 portable and 0 50 100 150 200 250 300 350 F lightweight 66 38 93 121 177 C 149 -18 10 Soak Temperature enough to Soak Temperature operate on a Copyright © 2011 Boeing. All rights reserved. FIGURE 2. Heat Soak Results: Delta-E vs. temperature after 60 days, thermally cured color movable paint coat + clearcoats platform or cart. The paint the engineering and appearance properties used as a must be sensitive enough, and the UV irradiance high predictor of successfully passing the qualificationenough, to enable a sufficiently high coverage rate of test and appearance-test batteries. Table 2 (page 45) the cure lamps over the painted surface to maximize illustrates the progress made toward satisfying these the flow-time savings and offset the higher equipment requirements in “stop-light” format (green = passing, costs associated with UV cure. There is also a fire-safety red = failing, yellow = marginally passing, needs requirement calling for explosion-proof (NFPA Article adjustment). 500, Class-I, Division-1) operation to enable curing in the paint hangar. These factors tend to favor a one-bulb, • Heat-resistance requirements. Finally, the paint formula UV-A cure system that is either intrinsically safe or can must also be resistant to yellowing, and slow the be enclosed in a positive-pressure inert-gas envelope. yellowing process in underlying paint, to a degree that justifies the time and expense of adding an extra coat • Overspray cure requirement. Since it is impossible to of paint. This requirement has proven to be especially channel 100% of overspray droplets into the paint hangar challenging, and although substantial progress has been air exhaust, every surface of the hangar eventually gets made toward this goal we cannot anticipate the degree coated with a fine layer of overspray droplets. This is to which the discoloration can ultimately be mitigated. not a problem with thermally cured paints; the droplets Because of this we have set the requirement as “best merely harden where they land. With UV-curable paint, available performance.” This indefinite level will be the overspray droplets will remain wet indefinitely, assessed to determine the business case for implementing which is clearly unacceptable. A secondary cure process the clearcoat as a heat-resistant coating. (“dual-cure”) is the typical approach: The overspray droplets eventually harden enough via a secondary cure mechanism to minimize safety concerns (typically within Progress to date: We have tested clearcoat formulations from two suppliers. The formulations went through several cycles 12 to 24 hours). This secondary mechanism does not of test, reformulation and retest. At present we have obtained require UV exposure and can proceed in the dark. substantial reduction in discoloration for the UV-curable clearcoat applied to the control color coat, compared to the thermally cured • Engineering and appearance requirements. In addition control clearcoat applied to this same color coat. These clearcoat to those above, the paint formula must satisfy all the formulations are also passing the application and engineering test engineering and appearance requirements established for thermally cured paint. Table 1 (page 44) lists page 42 u 40 | UV+EB Technology • Issue 2, 2016 +

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COATINGS Fig.3: Development flowchart

t page 40

Benchmark technology; survey potential suppliers

Down-select suppliers for screen testing

Formulate and screentest

Qual test

Downselect for qual testing

Reformulate/ retest

Reformulate/ Retest as needed

Painter application/ cure trials

Down-select cure technology

Prototype production cure system

Test cure technologies

Spec coverage; production trials/ implementation

Production system

Green = coating formulation/test Violet = cure system development/test Dark color = steps completed or in progress Red bars = business-case study gate

Copyright © 2011 2010 Boeing. All rights reserved. FIGURE 3. Development flowchart

requirements, with only minor adjustments needed to move to the full qualification-test battery. However, it is not clear if we are yet observing any lessening of discoloration of the underlying paint. In the coming months we expect to test several new formulations that we hope will show further improvement. In the heat-soak tests, aluminum test coupons were coated with the standard thermally cured paint stack-up (conversion coating, primer and pigmented urethane), then coated and cured with either thermally cured or UV-curable clearcoat. Color and gloss measurements were obtained before exposure and at several times during exposure to look for trends. Panels were exposed to temperatures ranging from room temperature to 150°C (302°F). The color values were used to obtain delta-E as a function of soak time and temperature. Figure 2 shows the observed behavior of delta-E (hence discoloration) at a soak duration of 60 days, over the range of soak temperature studied. In each plot, delta-E is plotted against soak temperature. The three plots show a thermally cured white paint (color coat) without clearcoat (dark blue), the same paint with the best-performing thermally cured clearcoat (light blue) and with the best-performing UV-curable clearcoats (red and violet) from the two suppliers. 42 | UV+EB Technology • Issue 2, 2016

After 60 days’ soak, insignificant discoloration was seen at the room-temperature “control” soak and at 70°C (158°F), which is near the maximum temperature experienced away from the hotexhaust vents. Significant discoloration was seen for all paint combinations tested at 120°C (248°F) and 150°C (302°F). These temperatures were chosen to simulate the conditions near the hot-exhaust vents. Over the soak temperature range studied, a consistent improvement is seen for the UV-cured clearcoats over the thermal clearcoat, although neither UV-curable clearcoat showed any clear evidence of mitigation of discoloration of the underlying pigmented paint. The substantial scale of the improvement (about 50% for the best-performing formulation) gives us hope that we can at least match the performance of the white paint with a “basecoat-clearcoat” system. These results, taken together, are very promising given that, after a long period of development, we are at the point where we could qualify one or both of these UV-curable formulations to the applicable exterior specifications for use as a general-use, fastcure clearcoat. UV-curable paint development at Boeing—a gated process: The development process followed the flow as depicted in Figure 3. It is a series of development phases +

are tested for the remaining properties listed. All of the remaining properties, except for heat resistance, give us a preview of the general engineering performance as an exterior paint.

connected by gates. At each gate the test results are assessed and a business case analysis performed to support the decision to proceed to the next phase. The development phases are as follows: •

Identifying formulators. We began the development process by canvassing the industry for formulators who either had an off-the-shelf product with potential for meeting our requirements, or who had the resources and interest in developing a clearcoat for us. We identified two formulators who began the process of formulating and submitting liquid and cured samples for us to test. While we work with these formulators we are continuing to check for additional sources with either an off-theshelf product or the potential for developing a product meeting our requirements. Iterative screen-testing of submissions. To expedite the test process, a battery of screen tests is employed that is a subset of the full qualification-test battery included in the paint specification. The test battery is listed in Table 1. The first five properties are tested only on samples applied and cured in our lab. They give us an overall idea of the spray and cure properties, and hence the application suitability of the formula. All samples +

After initial tests several iterative cycles of testing, reporting of results to the formulators and submission of reworked formulations follow until we test formulations that are close to satisfying the screen-test requirements. As anticipated, the greatest challenges have been in achieving adequate surface and through-cure with a single bulb, and resistance to yellowing during accelerated weathering. Results to date, however, suggest ways to meet these requirements through adjustments to the paint formula and to the cure process. •

Qualification testing and incorporation into the specification. Once we obtain a formula satisfying the screen-test requirements it will be sent through the entire qualification-test battery. We anticipate several more iterative cycles of testing and resubmission as adjustments to the photoinitiator package, thixotropes and other additives, as well as residual adjustments to reactive diluent and oligomer components. page 44 u

UV+EB Technology • Issue 2, 2016 | 43

COATINGS t page 43 Table 1: Criteria used to screen-test samples • Concurrent cureTABLE 1. Criteria used to screen-test samples system development. Concurrent to Property Target formulating the paint, Spray temperature Optimized for Boeing paint process we evaluated several approaches to the cure “Hang” time process. To obtain Cure energy density adequate through cure in the least exposure Cure irradiance time and with the Overspray cure (tack-free) lowest UV irradiance, the oligomeric resin, 60 deg Gloss Equal or better than qualified paint reactive diluent and photoinitiator Pencil-scratch hardness* package all need Leveling to be optimized for the irradiance and Fluid resistance—MEK, IPA, 100 rubs spectral output of the Fluid resistance—Skydrol, 30 days* curing lamp system. For the formulas Scribe adhesion (tape-pull)* presently under Droplet jet test* development we identified an optimal Impact resistance (Gardner)* UVA irradiance range and energy density Thermal shock* range for obtaining Weatherometer (500 kJ) deltaE** through-cure with maximized coverage Weatherometer delta gloss rate (i.e. minimized Heat resistance Meet requirement cure time) for the paint formulas being * Values over abraded undercoat. **Per SAE J1960 protocol developed. Copyright © 2011 Boeing. All rights reserved.

To satisfy our safety and process-engineering requirements we are focusing on a one-bulb UVA process. We adopted conventional UV lamp technology due to its technical maturity. While LED-based curing would be ideal for our application, and is well established for curing printing-ink films, it still lacks technical maturity at the performance levels required to cure paint films at the coverage rates we require. This technology is developing rapidly, and we will be testing formulations cured by this technology. Delivery of the UV to the painted surface could be accomplished either by (1) UV lamp fixtures installed throughout the hangar and surrounding the airplane (including floor units for the underside) or (2) by scanning a lamp system over the surface. The former scheme, while conceptually simple (just throw a switch to effect the cure) and fast (all painted areas exposed simultaneously), was rejected as prohibitively costly and unsafe due to stray UV radiation. Also, since the hangar would be off limits during cure, no simultaneous operations could proceed. Thus we adopted the idea of 44 | UV+EB Technology • Issue 2, 2016

scanning the UV lamps over the painted surface, as is done in the automotive industry. In our case the lamp array is moving, not the painted surface. Thus, the actual effective cure time would be the time required to “paint” the surface with the required energy density per unit area of UV. This overall cure time is dependent not only on UV irradiance and paint sensitivity but also on the time required to set up and maneuver the cure lamps over the entire painted surface. •

Scale-up to curing large test substrates. When we obtain a qualifiable paint formula and associated cure process at the lab-bench scale, the next step is to scale up to a lab system capable of curing large substrates in a manner simulating the “push-broom” coverage process expected on the airplane.

Application and cure on simulated airplane sections. The next development phase is scale-up to a productionprototype cure system that is explosion-proof and capable of operation on a paint platform or mobile cart on the floor. This prototype will be evaluated +

in simulations of representative aircraftpainting scenarios, and any residual issues with cure system or paints addressed. Scrapped fuselage skin panels, similar in size to the area to be painted in production, will be used for these trials, which will be conducted in the paint hangar with the painters who would be painting customer airplanes. •

Table 2: Engineering Screen Test Results: Best Formulations to Date

Production trials on customer airplanes. Finally, if all continues to proceed nominally, we will move to a netconfiguration cure system and production trials on customer airplanes chosen in the same manner as for any new coating or marking system.

TABLE 2. Engineering Screen Test Results: Best Formulations to Date


Supplier A

Supplier B

Spray temp “Hang” time Cure energy density Cure irradiance Overspray cure (tack-free)

In work

60 deg Gloss Pencil-scratch hardness* Leveling Fluid resistance—MEK, IPA, 100 rubs Fluid resistance—Skydrol, 30 days* Scribe adhesion (tape-pull)* Droplet jet test* Impact resistance (Gardner)* Thermal shock* Weatherometer (500 kJ) deltaE** Weatherometer delta gloss**

As each phase of development * Values over abraded undercoat. **Per SAE J1960 protocol is completed we will conduct a business-case study Copyright for © 2011 Boeing. All rights reserved. manage the development process, in particular to ensure that proceeding to the next step. Presently we are assessing the resources and expertise are most effectively deployed. best path for qualification testing. Once one or more paints pass the qualification-test battery we will revisit the business Conclusions: Significant development remains to achieve the case to determine whether it makes sense to go to an initial objective of a UV-curable clearcoat that confers useful protection implementation. The follow-on development phases (largefrom heat-induced discoloration. Even if we do not achieve useful scale lab testing, painter trials and production trials) will then be heat protection, the clearcoat formulas developed in this work planned accordingly. Conceivably at any point the business case may find use as specialty coatings elsewhere on the airplane. may not close, at which point the results will be documented for More applications may be possible if pigmented versions can be possible reevaluation in the future, as technology improves and developed in follow-on work. u the business needs change. However, even in the event of a decision to terminate the effort, we anticipate that the unique application and cure testing resources put in place for the development effort can be utilized in other ways. An example of this would be to provide testing services in support of contract research and development work assigned to our labs. A collaborative effort: As described previously, development of a successful UV-curable paint formula must be dovetailed with the development of a curing system for it. To facilitate this process both paint formulators are working closely with a curesystem developer and raw-material suppliers as well as with the end user. Meetings among the various stakeholders are held to +

Richard W. Baird has 26 years of engineering experience with Boeing, including 23 years combined in Commercial Airplanes and Boeing Research and Technology. His accomplishments have included development of UV-curable exterior decorative finishes; development and implementation of robust decals and appliqués for exteriors; development of novel exterior decoration processes; testing and implementation of environmentally compliant and more durable finishes and sealants for exterior and interior use; and physical and chemical characterization of finishes and finishing processes. Baird has a B.S. in chemistry from Caltech and M.S. in chemical engineering from MIT.

UV+EB Technology • Issue 2, 2016 | 45

LED WAVELENGTH By Mike Higgins, east regional sales manager, Phoseon

Understanding Ultraviolet LED Wavelength What is Ultraviolet Wavelength? he sun is a source of the full spectrum of ultraviolet radiation, which is commonly subdivided into UVA, UV-B, and UV-C. Wavelength, a fundamental descriptor of electromagnetic energy, is the distance between corresponding points of a propagated wave. Typical UV light source emission wavelengths range from ultraviolet (UV-C: 100 to 280nm; UV-B: 280 to 315nm; UV-A: 315 to 400nm) to visible light (400 to 700nm) and infrared (700 to 3000nm).


UV wavelengths typically are measured in nanometers (nm). Nanometer, a unit of length, is equal to one billionth of a meter. UV light-emitting diodes (LEDs) have a narrow spectral output centered on a specific wavelength, +/- 15nm, with typical commercial UV LED lamps emitting at 365nm, 385nm, 395nm or 405nm wavelengths. The irradiance (W/cm2) produced by UV LED light sources has increased consistently year over year because of advancements in both diode and lamp technology, and now is available at effective outputs higher than those offered by traditional UV curing lamp technologies. UV LED lamp systems have enough power to conquer a wide range of applications and today are being used commercially to cure inks, coatings and adhesives. Today, UV LED curing lamps offer peak irradiance up to 24W/cm2 (water-cooled) and 16W/cm2 (air-cooled) at 395nm, and that number will continue to increase. UV LED systems at 365nm are available offering peak irradiance of 12W/cm2 (water-cooled) and 8W/cm2 (air-cooled). Why are we Limited to High UV-A Wavelength? Wavelengths emitted by UV LED lamp systems are determined by the characteristics of the diodes selected in the lamp manufacturing process. UV LEDs are manufactured by a handful of companies both domestic and international. Globally, demand for LED diodes is driven by automotive, general lighting, mobile device and signage applications. Despite higher profit margins on UV LED diodes, market demand pales in comparison to larger, global market drivers such as general lighting and signage. While UV-B and UV-C diodes exist, they currently are limited by low power, an extremely short lifetime (~500 hours) and price points that can be 250 times the price of UV-A diodes. As a result of high demand for UV-A diodes in the aforementioned markets, most UV LED development work over the last 14 years has been focused on 365 to 405nm. Diode performance in this wavelength region is well understood and lifetime expectations exceed 20,000+ hours. It is important to note that long lifetimes are not a given. All UV LED lamps are not created equal, and it is important to fully understand the specifications of a lamp system before making an investment. Continued price pressure on UV LED is limiting the pursuit of shorter wavelength UV LED systems. Therefore, it is safe to assume that 365 to 405nm will be the dominate market offering for UV LED for the foreseeable future. The Photopolymerization Process Polymerization is a process in which small molecules are reacted chemically to form very large molecules and molecular networks called polymers. In the coatings, ink and adhesives industries, this process is also known as curing, drying or hardening and converts liquid formulations into a hard solid film or elastomeric solid with properties designed for the application. Photopolymerization utilizes the photons (UV or visible wavelengths) emitted by a lamp source to initiate the chemical reactions by excitation of special additives called photoinitiators. Upon absorption of the UV energy, the photoinitiator (PI) produces a highly reactive chemical species that initiates the reactions that tie the resinous components (oligomers, monomers, etc.) together (crosslinking) to cure or solidify the ink, coating or adhesive. 46 | UV+EB Technology â&#x20AC;˘ Issue 2, 2016 +

Formulating UV Chemistries for UV LED Lamps UV formulations for inks and coatings typically contain binders (oligomers, resins), diluents (monomers, water, or solvents), photoinitiators, and additives. Diluents are often necessary to reduce the viscosity of the formulation to enable application by spray, jetting, roll-coat, printing, or other techniques. Monomers can take the place of water or solvent for more environmentally friendly formulations, and serve to control viscosity while also being chemically incorporated into the resulting polymer network, reducing emissions and/or energy consumption compared to waterborne or solvent-borne formulations. The oligomers (and their backbone structure) determine the overall properties of the material. Monomers and oligomers in UV formulations are generally derivatives of acrylates or methacrylates containing polyurethanes, polyesters, polyethers or acrylic chemistries. Colorants such as pigments and dyes provide color and special effects, while silica, waxes, clays, and extenders are used to affect physical properties and sometimes to reduce the cost of formulations by replacing part of the more expensive binder components. Additives such as adhesion promotors, dispersants, flow-aides, degassing agents, UV stabilizers and others are used to improve specific properties of the formulations during the physical application process and after curing. To achieve efficient and effective UV curing of an ink, coating or adhesive, the formulator seeks to match the UV lamp spectral output with the absorption characteristics of the photoinitiator(s) used in the formulation. The amount of PI in a typical UV formulation is usually very small, less than 5% by weight. PIâ&#x20AC;&#x2122;s typically absorb across a range of wavelengths, not a single narrow band, and most existing UV formulations developed for curing with a typical mercury-arc lamp use a broad-spectrum PI. While there is often some absorption within the UV LED output range, it is clear that much of the conventional PI absorption +

range is not utilized when formulations are cured with a singleband UV LED lamp. A more efficient cure is possible with a formulation designed specifically for UV LED curing using a PI with high molar absorptivity in wavelength bands emitted by the UV LED source. Since current-generation UV LED emission wavelengths are strongest at 365nm and 395nm, photoinitiators and other formulation components should be selected to allow efficient excitation of the photoinitiator(s) at those wavelengths. Depth of penetration into a coating, ink or adhesive formulation during curing depends on the absorptivity (optical density) of the formulation at each wavelength. The optical density at each wavelength is determined by the selection of the resin components, colorants and additives that compose the formulation. In UV formulations we find that UV-C wavelengths typically are absorbed in the surface layers due to high optical density of the resins and other formulation components at the shorter UV wavelengths, while UV-B and UV-A penetrate more deeply into the film even to the point where formula meets substrate. Thus, the formulator must not only match the absorbance bands of the photoinitiator to the UV emission wavelengths of the UV LED lamp, but also must consider the absorption characteristics of the colorants (dyes, pigments), resins (monomers, oligomers, binders) and other additives in the formulation to avoid competitive absorption that can prevent the UV wavelengths from reaching the photoinitiator. The longer wavelength output, such as the UV-A range emissions from current high-irradiance UV LED systems, penetrates through thick and pigmented systems more easily than UV-B or UV-C wavelengths, producing through-cure of the material that typically improves adhesion and the ability to cure thicker screen ink or pigmented wood coatings. Shorter UV wavelengths (200 to 280 page 48 u UV+EB Technology â&#x20AC;˘ Issue 2, 2016 | 47

LED WAVELENGTH t page 47 nm) are unable to penetrate very deeply into a material, but provide surface curing, which is important for properties such as scratch and chemical resistance. Tailoring the formulation composition to take advantage of the specific UV wavelengths emitted by the UV LED source being used can significantly improve the depth of penetration and the degree of cure of a UV formulation in specific applications. Irradiance and Energy Density The physical and chemical properties of a UVcured formulation are significantly impacted by the degree of cure (extent of reaction or crosslinking) of the components in the formulation. The degree of cure may vary as a function of depth in the coating/ink and as a function of the curing conditions, and is often determined qualitatively by scratch, pencil hardness, or solvent resistance. Generally, the more photons absorbed by the photoinitiators in the formulation, the more chemical reactions and the higher degree of cure / crosslinking / etc. (Note, however, that more is not always better!) Energy density (slang term: dose) and irradiance (slang term: intensity) are two key parameters that help to characterize the curing conditions experienced by a UV formulation, and provide two specific variables that can be monitored and tweaked to optimize the overall properties and performance of the UV-cured material. In simplistic terms, irradiance is a measure of how “bright” the UV source is as observed by the surface of the formulation during curing. Also stated simply, energy density is a combination of how “bright” the UV source is and how long the formulation is exposed. More specifically, irradiance is the instantaneous number of photons at a specific wavelength or range of wavelengths striking the surface per unit area, and is expressed in watts per square centimeter. Peak irradiance is the maximum irradiance that the surface experiences during the curing process. Energy density is the time-integral of irradiance and represents the total sum of photons of a specific wavelength or wavelength range received by a specific area of the surface within a specific length of time.

Energy density is typically expressed in units of Joules per square centimeter. Measuring Irradiance What device should be used to measure the output from UV LED lamps? Several manufacturers provide products to measure irradiance and energy density. The sensors used in most current radiometers have been characterized and calibrated to work with the output profiles of mercury lamps and have not fully accommodated the unique emission characteristics of UV LED sources. Since UV LEDs have a very different emission profile, the sensor calibration for a given wavelength band is the most important characteristic. A radiometer that crops or doesn’t count all of the UV emission based on a normal LED wavelength tolerance can lead to measurement errors and should not be used to set irradiance specifications. The spectral characteristics of UV LED lamps are significantly different than those of traditional systems, and radiometers that will accurately measure UV LED emissions are just coming onto the market. Even then, radiometers need to be calibrated for specific characteristics of LEDs from specific lamp manufacturers.

In UV formulations we find that UV-C wavelengths typically are absorbed in the surface layers due to high optical density of the resins and other formulation components at the shorter UV wavelengths, while UV-B and UV-A penetrate more deeply into the film, even to the point where formula meets substrate. 48 | UV+EB Technology • Issue 2, 2016 +

A “generic” UV LED radiometer that can be used with different UV LED lamps does not currently exist. For process control, it is important for OEMs and end-users to utilize a UV LED radiometer that is calibrated to the UV LED lamp provider’s specifications. Otherwise, false readings and/or improper conclusions are the likely results. Measuring irradiance is not a simple task. UV LED lamp manufacturers, measurement device manufacturers, OEMs, and end-users should align around a single industry standard that can be used to consistently, accurately, and succinctly report irradiance and energy density measurements. Conclusion UV energy emitted from UV LED lamps and UV energy emitted by conventional mercury arc lamps or microwave lamps is all in the form of photons of specific wavelengths. That is, for purposes of UV photopolymerization, photons are photons, with the only differences being in quantity and wavelength. The distribution of wavelengths emitted by UV LED lamps is much narrower than the distribution of wavelengths emitted by conventional UV sources, and as a result, formulations and radiometers used with UV LED lamp systems must be matched to the emission bands of the UV LED lamp used in that curing system to achieve optimal performance. +

UV LED-based curing is now an accepted, user-friendly tool in printing, coatings and adhesive markets, and UV LED system characteristics are enabling a number of applications that were impractical or limited by physical constraints of conventional UV sources. These industry users and UV LED suppliers continue to challenge formulators and chemical raw material suppliers to develop and supply UV LED wavelength-optimized materials and formulations. At the same time, UV LED curing units have become more efficient in delivering UV energy to the media, thus driving not only environmentally clean, energy-efficient and compact-size units but also enabling increased throughput and process flexibility. u Mike Higgins is east regional sales manager for Phoseon Technology and a member of the Editorial Board for RadTech. After nine years with Sartomer, Higgins has spent the past three years supporting the rapidly growing LED market. Experience in both acrylate chemistry and next generation equipment has given him a unique perspective and understanding of the UV-curable marketplace, as well as insight into potential applications and future growth. For more information, email or visit

UV+EB Technology • Issue 2, 2016 | 49

WINTER MEETING By Dianna Brodine, managing editor, UV+EB Technology

RadTech Winter Meeting R

adTech held its annual Winter Meeting February 25-26 at the Radisson Resort Orlando-Celebration in Florida. A group of RadTech board members, committee leads, suppliers to the industry and interested members assembled to advance the work of the association in the UV, EB and LED markets. RadTech committees, including 3D Printing, Printing and Packaging, Market Outreach, Education, Automotive/ Transportation, LED and EHS held meetings. The Transportation committee discussed its partnership with SAE for the 2016 World Congress and Exhibition. RadTech hosted a day of technical sessions at the event on April 14, with speakers from Allnex, Red Spot Paint & Varnish Company, Inc., Heraeus Noblelight America and Sartomer USA. Christopher Seubert, Ford Motor Company, was the chairperson of the event. In addition, a potential update to an automotive UV-curing supplement from 2002 was considered, and an update on the New York State Vehicle Composites program was distributed. The Education committee contemplated student incentives for membership and updated the group on the progress of both the RadTech student lab competition and the TAGA/RadTech student poster competition. Additional outreach plans for regional/metropolitan areas and academic/governmental institutions were discussed. The UV LED committee reported 600 downloads of version 2 of the UV LED eBook in the first two weeks following its release. UV LED 2015, the association’s first event dedicated to LED technologies, also was a success, with 25 tabletops and 250 attendees gathering in October in Troy, New York. Printing and Packaging meeting attendees spoke about ways to continue to gain exposure through relationships with other trade shows and/or conferences. A discussion was held on the success of the LED curing panel last fall at SGIA (Specialty Graphic Imaging Association) and the feasibility of another panel presentation in 2016. Other associations were mentioned, including AIMCAL (Association of International Metallizers, Coaters and Laminators) and the possibility of working with the group on a panel or paper session at the upcoming AIMCAL fall conference. The EHS committee tackled the difficult topic of safety and compliance in response to the outpouring of growth in the 3D printing arena. A Safe Handling of UV Materials Used in 3D informational flyer was created and input received from those in attendance. The intent is to fill a need for information to be provided to those without chemical-exposure training, but with access to the plethora of 3D printing equipment now available in the consumer market. Market Outreach continued its drive to expand the reach of both the association and the technologies that are central to the association’s mission. The implementation of the RadTech Resource Bureau was announced. It will serve as a hub to connect organizations wanting to disseminate information on UV/EB technologies through speaking opportunities, article possibilities and more to those willing to share their industry knowledge. Relationships with Manufacturing Extension Partnerships (MEPs) also were discussed. A reception on the first evening of the event provided all attendees an opportunity to network with others in the field and continue discussions carried over from meetings held earlier in the day. The 2016 Winter Meeting was well attended and set the stage for important progress for the committees as the association headed into its premier event, RadTech 2016. u

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Regulatory News

Doreen M. Monteleone, Ph.D., director of sustainability & EHS initiatives, RadTech International North America doreen@

Toxic Substance Control Act Reform Late in 2015, the Senate passed a bill overhauling the Toxic Substances Control Act (TSCA), called the Frank R. Lautenberg Chemical Safety for the 21st Century Act (Lautenberg Act). One of the biggest proposed changes is the revision of the standard for determining chemical safety. Under the current TSCA, the US Environment Protection Agency (US EPA) conducts a cost-benefit analysis to determine whether a chemical is safe for its intended use. Specifically, this cost-benefit analysis allows US EPA to consider the cost of regulation when determining whether a chemical is safe for its intended use. The Lautenberg Act’s safety standard explicitly precludes the consideration of cost or other non-risk factors in determining whether a chemical poses an unreasonable risk of injury to health or the environment. Reforms to the TSCA have not yet been signed into law. However, the recent passage of both the Lautenberg Act and the related bill in the House of Representatives shows these changes are likely coming. To prepare for this overhaul of the TSCA, companies should start considering how the proposed changes might affect the products they sell and their businesses overall. Learn more at senate-bill/697/all-info. E-Manifest Update US EPA’s e-Manifest system, designed to replace the current multiple-page and signature hard copy system, will begin functioning in the spring of 2016 with full implementation two years later. By the end of the second quarter of 2016, US EPA will propose a user-fee regulation for using the system. Only generators, haulers, disposal facilities and other waste handlers will pay the fee. States and members of the public who access the manifests will not. The goal of the fee will be to fully recover all costs of the e-Manifest system. Learn more at epawaste/hazard/transportation/manifest/e-man.htm. US EPA to Write Spill Prevention Rule US EPA has agreed in a settlement with citizen groups to write a major new chemical plant safety rule. The Natural Resources Defense Council has stated, “The Environmental Protection Agency will put in place new safeguards to help protect communities from dangerous chemical spills at tens of thousands of industrial facilities nationwide, under the terms of a legal settlement approved by a federal district court in New York. The agreement is meant to strengthen protections as called for by Congress more than four decades ago.” Learn more at OSHA Extends Public Comment Period on Guidance for Health Hazards of Chemicals The approach, known as weight of evidence (WoE), assists manufacturers, importers and employers to evaluate scientific studies on the potential health hazards of a chemical and determine what information must be disclosed on the label and safety data sheet for compliance with the Hazard Communication Standard (HCS). To allow stakeholders more time to review and comment, the Occupational Safety & Health Administration (OSHA) extended the public comment period to May 2, 2016, for its draft Guidance on Data Evaluation for Weight of Evidence Determination. Learn more at OSHA Onsite Consultation Program Consultants from state agencies or universities work with employers to identify workplace hazards, provide advice on compliance with OSHA standards and assist in establishing injury- and illness-prevention programs. Onsite consultation services are separate from enforcement and do not result in penalties or citations. Visit OSHA’s website at to find your local Onsite Consultation Program office. Reducing E-Waste through Purchasing Decisions Purchasing decisions for electronic office equipment, such as computers and printers, often are not made with the equipment end-of-life disposition in mind. Purchasing agents develop technical specifications for office equipment and make final purchasing decisions based on the needs of their users. The end result is that final disposition of this electronic waste, or e-waste, may sometimes be through the trash or through unchecked

52 | UV+EB Technology • Issue 2, 2016 +

Regulatory News third-party disposal companies, which increases the potential for contaminants to enter the environment. The most prevalent and widespread barriers to using best management practices for purchasing and recycling of electronics were (1) a lack of awareness around electronics purchasing and recycling certifications and registries, and (2) persistent negative perceptions around electronic certifications and registries. Learn more at

News from the West Coast

Rita Loof, director of regional environmental affairs, RadTech International North America

RadTech Selected to SCAQMD Committee RadTech International was honored to have been selected as a member of the newly created “Working Group for Ad Hoc Committee Large Compliance Investments and Future Regulatory Certainty” of the South Coast Air Quality Management District (SCAQMD). The association submitted comments stressing incentives for businesses to voluntarily convert to pollution-prevention processes, such as UV/EB. This industry has long advocated for permit streamlining by providing exemptions to UV/EB processes under SCAQMD Rule 219 (Permitting exemptions). “Certainty is increased by eliminating the uncertainties of the permitting process. Eliminating unnecessary permitting also alleviates the district’s permit backlog,” commented Rita Loof, RadTech’s director of regional environmental affairs, in a letter to the district. RadTech also supported the concept of not excluding larger businesses from any incentive, grant or other support program. The association offered to partner with the district in its goal to provide trainings and education, in the context of UV/EB technology. A place was suggested on the district’s website for a link to the RadTech website for businesses that want to learn more about the technology. RadTech expressed concern with language in a document stating: “…… some entities who typically prefer emission control equipment to be mandated.” The district was cautioned to equitably treat UV/EB (pollution prevention) technologies rather than offer a preference to processes that generate pollution and install add-on emission controls. SCAQMD Selects Interim Executive Amid public disruptions by protestors dressed in clown costumes yelling at the monthly meeting, the SCAQMD board voted unanimously to appoint Wayne Nastri as its interim executive officer for a six-month period, pending a search for a permanent candidate. The board approved a yearly salary of $271,000, plus benefits and the use of a district car. The move follows the board’s controversial decision to terminate the employment of longtime Executive Officer Barry Wallerstein. Nastri held the position of administrator of the federal Environmental Protection Agency’s Pacific Southwest region during President George W. Bush’s administration. He was the president of the environmental and energy consulting firm E4 Strategic Solutions, which has represented companies before the SCAQMD. At one point, he served on the SCAQMD board. Environmental groups expressed concern over the hiring of an “industry lobbyist” to serve as the agency’s chief. They fear that the decision is a signal that the agency is moving toward a more business-friendly climate. The disruptors were escorted out of the board room by security guards, as it is against California state law to disrupt a public meeting. State legislators have announced they plan to appoint additional members to the board to avert any potential effort by the SCAQMD to adopt pro-business regulations. The effort to change state law to alter the board’s composition is underway. u +

UV+EB Technology • Issue 2, 2016 | 53

Technology Showcase Allnex Introduces New Multi-Functional Binder Allnex, Brussels, Belgium, launched a solvent-free UV-curable binder, EBECRYL® 898. When combined with a matting agent, EBECRYL® 898 helps to achieve substrate-specific end properties on wood, resilient flooring, plastic and paper foil substrates without the need for added solvent or monofunctional diluents. EBECRYL® 898 provides an ultra-matte effect to the final coating and keeps gloss levels very low without sacrificing mechanical performance properties. It can be used in ultra-low and low gloss finishes applied at a wide range of dry film thicknesses ranging from 3 to 100 microns. It also is suitable for clear and colored systems used as top coats or self-sealing coatings that are applied by spray, curtain or roller coating. For more information, visit FUJIFILM Announces the New Acuity Select 20 Series FUJIFILM North America Corporation, Hanover Park, Illinois, announced the release of the new Acuity Select 20 series. Introduced as a replacement to the existing Acuity Advance Select series, it maintains all the advantages of the Acuity UV flatbed printer and incorporates new features. The 20 series includes the option of using light cyan and light magenta to further enhance print quality for those producing fine art or photographic images. Productivity is improved with the addition of a pneumatic pin registration system, and the vacuum system now features an improved high-pressure vacuum, designed to reduce the need for masking of the bed for easy loading of media. For more information, visit Clariant Unveils New Adiditives Clariant, Muttenz, Switzerland, has introduced water-based light stabilizers and renewable-based wax additives that combine an offering for a more natural, sustainable product. Clariant’s Hostavin® water-based dispersions provide a step-change in UV stability performance that helps prevent the unwanted effects of weathering on wood coatings such as substrate discoloration, loss of gloss and subsequent cracking and blistering of a finished coating. Clariant’s Clariant confirms sustainability and best100% renewable performance can go hand-in-hand for micronized Ceridust® water-based wood coatings. waxes enable the creation of waterbased wood coatings that offer both scratch resistance and innovative surface feel through unique texturized or soft-touch effects. Hostavin light stabilizers and Ceridust micronized waxes support the replacement of solvent-based coatings and will enable coating formulators to offer more environmentally friendly products. For more information, visit

54 | UV+EB Technology • Issue 2, 2016

Siegwerk Introduces New Ink Series Siegwerk, headquartered in Siegburg, Germany, introduced SICURA Nutriflex LEDTech, a low-migration series for UV printing machines with modern UV LED technology. These inks work for a wide range of plastic materials and other substrates and are suitable for processing with all inline types of UV LED label or packaging printing machines. It is intended for use on pharmaceutical and hygiene products, while also being suitable for use on the non-food-contact side of food packaging. The inks are appropriate for heat sealing and lamination, silicon free and resistant to seep and shock-freeze. The inks of this series are designed for UV LED light with a wavelength of 395nm and are available in Yellow C E01 and HC E01, Magenta C E01 and HC E01, Cyan C E01 and HC E01, Black C E01 and HC E01 and White. For more information, visit Steinemann Adds To dmax Family Steinemann, Gallen, Switzerland, introduced two new digital varnishing machines, dmax 76 and dmax 76c. These products are designed to cover a wide range of demands for full-flood UV varnishing and spot varnishing in both commercial and packaging printing. The dmax 76 is designed for B1 formats and features divar inkjet technology. It is a narrower version for spot varnishing on paper and board sheets in sizes of up to 760x760mm. The dmax family is rounded off by an entrylevel model, the dmax 76c, with the same sheet format. Like the dmax 106, both machines offer a resolution of 600dpi and achieve an output of up to 10,000 sheets per hour. All models permit varnish application rates of four to 50 g/m², or optionally even up to 100 g/m², while at the same time offering high varnishing quality. The dmax 76 can be expanded into multifunctional finishing systems by adding options covering different demands on UV varnishing – including a module for printing barcodes. For more information, visit Dymax Curing Systems Enhance 3D Printing Dymax Corporation, Torrington, Connecticut, introduced a new application for its UV light-curing spot and flood-lamp systems that enhance configurations for 3D post-curing applications or help rework the model. These flood-lamp models use a powerful UV light-curing lamp (up to 225mW/cm2) for fast curing over a 5 x 5" (12.7cm x 12.7cm) area. For rework or repair, such as curing drain-hole fills, assembling larger assemblies or repairing cracked or broken models, the company’s BlueWave® 200 3.0 spot-lamp system is offered. This unit is a high-intensity lamp that emits energy in the UV-A and visible +

Technology Showcase portion of the spectrum (300450nm) and is ideally suited for either manual or automated processes. It contains an integral shutter, which can be actuated by a foot pedal or PLC, and a universal power input that allows operation globally and provides consistent performance at any voltage. For more information, call 860.482.1010 or visit Phoseon Addresses LED Output Degradation Phoseon, Hillsboro, Oregon, has developed TargetCure Technology for select models of air-cooled light sources. TargetCure Technology addresses current application challenges in over- and under-curing of materials, along with the degradation of LED output over time. It offers precise curing when the lamp is turned on, eliminating overshoot, providing a consistent and reliable cure. TargetCure Technology provides stable output through seasonal and daily temperature variations as well as over the lifetime of the unit by continually monitoring the lamp’s efficiency and adjusting output as it ages. For more information, visit Excelitas Introduces UV LED Curing Systems Series Excelitas Technologies® Corp., Waltham, Massachusetts, introduced its new OmniCure AC5 Series UV LED curing system for small area curing. The series provides a reliable UV light source for curing inks, adhesives and coatings in industrial and electronics applications, as well as in printing applications. The system features very high irradiance LED technology that can cure adhesives at a low temperature, which is needed for sensitive components used in medical device and electronics manufacturing. These curing systems are easily integrated into any workstation with no additional venting, ozone extraction or chillers required, and can be automated for increased productivity. The print versions are equipped with a replaceable outer winder required for printing applications at close working distances or with custom lenses to provide the highest irradiance at flexible working distances for specific applications. For more information, visit Toyoda Goesi Develops Gladd-Encapsulated Ultraviolet LED Toyoda Gosei, Kiyosu, Japan, developed a new glassencapsulated ultraviolet LED product with a fully sealed structure. Toyoda Gosei applied its existing glass-sealed package technology to ultraviolet LEDs in this product and completely sealed the LED die glass to minimize the impact of gas penetration and moisture on the die. This package can maintain high reliability in many different environments, including high temperatures up to 100°C and high temperature and humidity environments (85°C and 85% humidity). For the ultraviolet LED die used in the product, gallium nitride crystal growth technology was applied. The light output per LED die was raised +

by improving the crystal structure. Samples for use in curing light sources for resins, ink and adhesives were made available in April. For more information, visit GEW Introduces its NUVA2 UV System GEW, West Sussex, England, launched the latest version of its NUVA2 UV system for superwide applications available in widths up to 2.5m from a single lamp. The NUVA2 is a versatile, fully air-cooled UV system for web or sheet-fed applications in the printing, coating and converting industries. The active air-cooling and optically tuned reflectors maximize the lamp’s curing effect while at the same time reducing heat radiation onto the substrate. NUVA2 systems can be upgraded to LED operation. An arc lamp cassette and an LED cassette can be operated interchangeably and seamlessly on the same print unit using the same RHINO ArcLED electronic power supply, control panel and cabling. For more information, visit Enhancement Available for Heraeus Noblelight (Fusion) Microwave Lamps Heraeus Noblelight America LLC, Gaithersburg, Maryland, has created a new and improved RF gasket (patent pending) for use in all Heraeus/Fusion microwave-powered lamps. These retrofitable elastomer gaskets provide significant advantages when compared to traditional aluminum braided gaskets. Features include an improved fit, easier and faster installation, an improved R/F seal, elimination of potential arcing and improved lifetime performance. For further information, call 301.527.2660 or visit Honle UV AMERICA Adds Compact LED Chamber and New Powerline Unit Honle UV America has added the LED Cube 100 with LED Spot 100, a compact UV irradiation chamber for use in the laboratory or for manual production. By employing different LED units, the emission range is adjustable to various fields of application. This assembly, as well as an electronic power control, guarantees high intensity and homogenous distribution of light, and the comprehensive monitoring function provides high process stability. In addition, the new AC 820 IC is an air cooled highperformance UV LED array for intermediate and final curing for printing applications, as well as curing varnishes or UV-reactive adhesives. It comes in wavelengths of 365, 385, 395 and 405nm. For more information, visit us at u UV+EB Technology • Issue 2, 2016 | 55

Calendar MAY



24-27 RadTech Asia 2016, Hilton Tokyo Odaiba, Tokyo, Japan. For more information, visit

16-18 RadTech 2016, Hyatt Regency O’Hare, Chicago, Illinois. For more information, visit

16 RadTech Korea, Gyeonggi Technopark, Ansan City, Gyeonggi province, Korea. For more information, email or visit

5-6 The Inkjet Conference, Düsseldorf/Neuss, Germany. For more information, visit


13-15 Labelexpo Americas 2016, Donald E. Stephens Convention Center, Rosemont, Illinois. For more information, visit 25-28 GRAPH Expo 16, Orange County Convention Center-North, Orlando, Florida. For more information, visit

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Advertisers’ Index Alberdingk Boley....................................................................... 35 American Ultraviolet.................................................................. 21 A.W.T. World Trade Inc.............................................................. 30 BASF........................................................................................... Front Cover Carestream Contract Manufacturing....................................... 41 Collins Inkjet............................................................................... 49 EIT Instrument Markets............................................................. 23 Excelitas Technologies.............................................................. Cover GEW............................................................................................ 7 Gigahertz-Optik......................................................................... 16 GRAPH Expo 16......................................................................... Back Cover Heraeus Noblelight America LLC............................................ 25 Honle UV America Inc............................................................... 5 Kopp Glass................................................................................. 33 Labelexpo Americas 2016......................................................... 51 Miwon Specialty Chemical Co., Ltd......................................... 17 Nedap Inc................................................................................... 43 Phoseon Technology................................................................. 31 RAHN-Group.............................................................................. 1 Sartomer Arkema Group........................................................... 27 Siltech Corporation................................................................... 20 USHIO......................................................................................... 37

56 | UV+EB Technology • Issue 2, 2016 +

New people. New technology. A reimagined GRAPH EXPO comes to Orlando, Florida in 2016. GRAPH EXPO is the industry’s most exciting and all-inclusive LIVE showcase of the hottest technology in printing today. Sunny Florida—the international gateway to Latin America and beyond— will draw a fresh set of attendees and exhibitors. Together, in this stimulating community of colleagues, competitors, and top industry experts, you will make profitable new business connections, expand your knowledge, and discover exciting new print-driven pathways to success. If you’ve got a thirst for innovation and growth, quench it at GRAPH EXPO 16. September 25–28, 2016 Orange County Convention Center - North | Orlando, Florida GRAPH EXPO & PRINT, GASC Shows




Outperforms All Others for High-speed Curing of Inks, Adhesives & Coatings

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Achieve consistent curing results Exceptional reliability and process control Streamline integration with your assembly line Compact designs, simple plug-and-run operation 2260 Argentia Road, Mississauga, Ontario, L5N 6H7 CANADA

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UV+ED Technology Issue 2 2016  

UV+ED Technology Issue 2 2016  

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