Converting \flood Waste into Synthetic Boards

(The following is an address on a vitally important subject that was delivered by Robert A. Caughey before The American Society of Mechanical Engineers meeting at Worcester, Mass.)

For many years there has been a growing consciousness of the necessity for conserving our raw materials and natural resources, one of the most important of which is u'ood. It was long ago authoritatively reported that the national timber cut exceeded the growth of so-called sarv timber. This fact, coupled with the economic stresses engendered by two major war efforts and their consequent drain on timber resources, set in motion or accentuated widespread research activity in several directions. A basic phase of this activity lvas the promotion of better forest practice, aimed at producing more and better timber in less time, the reduction of fire and insect damage, better land utilization and improvements in lumber harvesting methods.

A second phase involved dealing with manufacturing improvements in methods of and equipment for the more complete utilization of solid rvood, every effort being expanded toward elimination of waste and the salvage of all usable portions of the lumber at hand.

A third phase, which is dealt with in part in this paper, is the utilization of the wood material which has alrvays heretofore been considered as rvaste by the 'rvood using industries. Aside from its major use as fuel, this material potentially forms the basis of several nerv rvood converting industries capable of tremendous growth. and rvhich mav have a pronounced effect on the national economy.

Because the volume of this rvood waste is so large, its complete utilization must necessarily involve business of majo- proportions of a size comparable rvith that of the paper industry. The familiar example is the rnanufacture of insulating board, such as is widely emploved in the building i'.dustr1', and rvhere production runs to billions of srluare feet annually, Here, horvever, we run into the anomalous situation rvhereby the size of the operation may require such amounts of rvood, and in such a form. that it becomes cheaper and mo:e satisfactory to use pulp logs rather than mill waste as the raw material. Also there is a definite limit to the amount of this type of board rvhicl-r may be consumed by the nation's building industry.

The development of the so-called hard boards, notably Masonite Presswood, and the more recent comparable or similar types, has been rapid, and has filled many requirements of the building and furniture indust-ies. Here again, properties of the product, coupled rvith price, make its application somervhat limited, rvhen considered in comparison with the total amount of wood products used; and while this market does not approach the same degree of saturation as does the insulating board market. nevertheless the effect on the total amount of rvood tvaste available is very small.

We are here concerned with a somewhat different approach to the problem of waste utilization, namely: the production of synthetic board materials having properties comparable rvith those of wood, and involving the use of synthetic resins for bonding small particles of rvood, such as sawdust or shavings, together. This is in distinct contrast to the manufacture of the above-mentioned soft, insulating board, or the hard board, both of which depend on the felting of wood fibers, under various conditions of heat, moisture and pressure.

Basically, the operations involved in making resin-bonded board materials are simple, being somewhat as follows: Relatively finely divided wood, such as shavin$s or sawdust, are mixed with an active synthetic resin of t?ie thermosetting type; the mixture is spread in a uniform layer on a suitable tray, rvhich is then inserted between the platens of a hydraulic press, rvhere heat and pressure are applied until the resin is cured, after u'hich the board may be extracted from the press and, rvhen cool, treated much as lumber or plywood. A tremendous range of physical properties may easily be obtained, (l) depending on the amount of resin, the degree of pressure, and the configu. ration of the wood particles and to a lesser extent on the type of resin and species of u'ood. At the present time. there is little doubt but that a synthetic board can be made for most of the applications where rvood is norv used, often doing a better job than lumber is norv doing.

There are horvever, a myriad of technical details to rvhich attention must be paid in the production of any synthetic board of uniformty high quality. Among these details are size and shape of wood particle, the type of resin and constant uniformity of its activitv and final properties. precise control of moisture of rvood and resin, exact conditions of compounding the rvood and resin mixture, the timing and consecutive operations throughout the process. and conditions of pressing operations to achieve maximum production rates and optimum properties.

For certain types of synthetic board all the production details have been solved, and at present boards for linoleum underlayment and, to a lesser extent, pl1'rvood core stock, are in successful commercial production. at a rate of several million feet per year in one small plant alone. The problems nos'before this particular business are nolv almost entirely economic, involving :

(l) price of competition product, rvhich in the case of undelayment is plyu'ood.

(2) cost of raw materials

(3) volume of production

A discussion of the board now being sold as underlayment for linoleum or asphalt or rubber tile, will illustrate the potentialities of the neu'type of material. The properties of the material are about as follows:

Thickness-/s"

I\fodulus of Rupture-1600 p.s.i.

\\reight-2.1$ per sq. ft.

Shear Strength--{X)-1000 p.s.i.

Thermal Conductivity-K-I.0 (approx.)

Screw and nail holdiing power-Superior to most soft rvoods

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Another yeor is closing ond we rejoice in the knowledge thot the old-time spirit of friendliness crnd co-opercrtion still is a worm recrlity in our doily lives. Your contribution to thcrt spirit is genuinely opprecioted here, ond it is c pleosure now to extend to you hecntiest greetings of the seqson.

Continued from Page 96)

Dimensional stability-Considerably better than wood when subjected to a very rvide range of humidity changes, but under prolonged immersion in rvater will increase more in thickness but less in width than wood.

Fire Resistance-Much superioi to wood.

Resistance to IndentationAbout equivalent to rock maple.

Tliis board, when used over a sub-floor, has all the advantages of fir plywood as an underlayment for linoleum, except that plywood is inferior with respect to indentation and "grain raising," but superior in flexual strength. Flexual strength is of minor importance here, horvever, since the underlayment is ahvays used over a wood or plyrvood subfloor.

This is an example of a material designed to fit a specific application; in this case it has been successful because the material is not only fhysically suited to the job but also is somewhat more uniform, less expensive and easier to work than is either lumber or plywood.

This board is now being thoroughly treated for use as sheathing on frame dwellings, and for roofers. It has been found capable of withstanding all the normal rveathering usually encountered during construction, and because of its strength and rigidity will support heavy roof loads, although rafter spacings would probably have to be closer than rvith 3/4' or 25/32'lumber.

Reference is here made to the address of Mr. Joshua Nickerson at the Wallboard Conference at Harvard IJniversity, September 16, 1949, (2) in which he describes an ideal wallboard for use as sheathing, roofers, subfloor, etc., emphasizing nail-holding power xnd strength, coupled rvith a cost not greatly exceeding that of ordinary sheathing lumber. A material which will meet all the requirements set forth by Mr. Nickerson, u'ith the possible exception of sufficient flexual strength in subflooring, can now be made, and when facilities for volurne production are complete, the cost of this material to the retail lumber yard will be about the same as that of common lumber sheathing. It rvill be ,easier to handle and much less expensive for the builder to use than either lumber or plywood. It will produce a more rigid structure than lumber, insulating sheathing, or gypsum board, and the structure will hold its shape better because the effect of rvind and other forces rvill produce less enlargement of the hole around nails than is the case s'ith any other commonly used material except plyrvood. In contrast to insulating siding and gypsum board. the nailholding power of the synthetic board will be equal to that of lumber, permitting completely random nailing of shingles, clapboards, or other siding, without use of special nails.

At the present time most bf these synthetic boards are being made with waste wood, primarily soft woods, it being found most advantageous to collect material from several sources, such as ground shavings, ground hogged wood, and even ground chips" produced from slabs with a pulp chipper.. Equally satisfactory material can be made by coarsely grinding pulpwood chips, produced from either hardwood or softwood pulp logs. Ultimately, the source' rvill be governed entirely by the cost of delivering material to the grill.

The economic importance of this development becomes immediately apparent rvhen s.e consider the relative degree of utilization of rarv material by conventional practice; for example, it is more or less generally agreed that in producing lumber for building purposes, furniture, etc., less than 3O/o of the rvood in the log reaches the ultimate consumer. Also. it must be borne in mind that of this 30% a verrr considerable portion is of inferior quality. Synthetic boards may be produced from logs or wood rvhich the lumber operator norv considers to be either decidedly inferior or completely unusable; the synthetic board, however, produced from this so called lorv grade or sub-marginal type of wood rvill be of uniformly high quality and can be made to specification such that a given quality can ahvays be maintained. Furthermore, the yield in terms of pound of finished product. per pound of rau' material may be cfose to 100%.

With a reasonable volume of production the number of board feet produced per man day may'be much higher in the case of the synthetic boards than rvith ordinary lumber.

Bibliography

(l) T. W. Sears-Wallboard Production & Uses-Bulletin 31, Pages 89-104 Northeastern Wood Utilization Council.

(2) Joshua A. Nickerson-Ibid. Pages 15-21.

Purchcses Brcmch Ycnd ct Orcnge, CcliL

The Orange County Lumber Company of Santa Ana, Calif., announced the purchase of a branch yard in Orange, Cdif., to be under the management of J. R. (Jack) McClure.

President Lou Adolphsen of the Orange County l-umber Company said the new yard in Orange is part of the company's plans to better serve the increasing business in that area- The yard is located at 324 West Chapman.

Assisting Manager McClure at the new Orange County branch will be John McClure, Sr., and Earl Piper, former personnel at the yard under its previous ownership, The Barr Lumber Company.

The yard will carry a complete line of lumber and building material as well as hardware and paint. "We will also continue our policy of building planning assistance that has proven so popular at our Santa Ana headquarters," Adolphsen declared.

The Orange County Lumber Company's head office in Santa Ana is at 720 Fruit Street.

Bcry Arec Buil.ling Record High

According to Max D. Kossoris, director of the western region of the U. S. Department of Labor's bureau of labor statistics, 1950 is by far the greatest year in the history of home building in San Francisco-Oakland metropolitan area. During the first nine months of this year, 24.llD permanent non-farm drvelling units rvere started in this area, and a total of over 30.000 before the end of the vear is predicted.

New Ptyrood Plcnt lor Astoric

Astoria Plywood Corp. is the name of a new concern which is going to build a plywood plant in Astoria, Oregon. The' report is that the capital stock has been fully subscribed, and that construction will start at an early date. The president of the concern is Norman Jacobson of Kalama, Washington.