Ponderosa Pine Woodwork Residues for Dry Formed Particleboard

With a serious shortage of plywood panels for use in its doors and kitchen units, the Curtis Companies Incorporated turned its attention to the daily accumulation of 25 tons of woodwork residues resulting from operations of the Clinton, Iowa Division, and asked its Research Department if good quality panels could be economically made from this material. Two years later a small production plant began to turn out sizeable quantities of a dry process particle board which is still being manufactured and successfully used in many items of woodwork. The dry particle board is a phenolic resin-bonded aggregate of ponderosa pine particles, ranging in size from those that will barely pass a 12 mesh screen down to those that are ordinarily spoken of as “fines,” or wood flour particles. The product has a specific gravity of approximately 1.0 and is termed “Prespine.” It has light color, hardness, high tensile strength perpendicular to the surface, excellent screw holding properties, good abrasion resistance, low linear expansion, good bending strength, good weathering resistance, and good machinability. The raw material for the board is hogged residue and machining residue, largely in the form of chips from 1 to 3 inches long, and from 1/4 to 3/4 inch wide. The aggregate of resin and wood residue at 14 percent moisture content is loaded into aluminum trays and pressed at 325 psi and a temperature of 320?F. for 4-1/4 minutes. The panels are air-cooled after removal from the trays and then sprayed with moisture to bring the panel to 6 to 7 percent moisture content after which they are flat piled to give the moisture a chance to distribute itself equally throughout the panel. The thickness of the panels is 9/32 inch. Sanding brings them to a thickness of 1/4 inch.

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