Manufacture of Consolidated Products from Wood Residues

This report provides information on the utilization of wood residues as raw material in the manufacture of board products, molded shapes, die-pressed materials, and other useful items using synthetic-resin binders. Indication is given from exploratory investigation that moderate particle sizes are most satisfactory for the production of dry process boards. While an exact range was not established it is estimated that an acceptable classification should include material that has a minimum mesh size of 0.05 inch and a maximum mesh size of 0.25 inch. A study of the effect of variation of resin content indicated that a board of acceptable quality could be made with a resin content of about 2.5 percent. Progressive depreciation of strength, water resistance, and other physical characteristics took place as resin content was decreased to 2.0 percent and lower. Improvement of physical qualities was realized when resin percentages were increased above 2.5 percent. Improvement tapered off rapidly as higher resin percentages, in the vicinity of 6 percent and greater, were used. The density. of a consolidated board is shown to be dependent on the amount of pressure applied. Other factors, such as density of the particular wood species used, temperature at time of pressing, and specific gravity of the resin binder are also shown to have an effect on the final product. To determine the feasibility of making die-shaped products, an experimental die was constructed to produce coasters for glasses. It was found that particles of standard mesh size, when coated with 5 percent binder and pressed at 5,000 pounds per square inch at 300?F., produced a product that had high strength and excellent water resistance. The effect of pressure and resin content on board surface appearance is discussed and data are given on modulus of rupture and water absorption of spray-coated 1/4-inch wood-residue board faced with a plastic paper and bonded with phenol formaldehyde resin. A spray-coating apparatus that permits controlled coating of a continuous feed of wood particles is described in detail.

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