FI42629B

913,395. Shaping hardboard. ABITIBI POWER & PAPER CO. Ltd. March 6, 1961 [March 21, 1960], No. 8105/61. Class 96. Shaped hardboard sheets are manufactured by die-forming with heat and pressure mats of bonded wood fibres which have been rendered flexible and capable of elongation by crushing, and, if desired, bending. The entire mat or selected areas only may be compressed, e.g. in a press or by pounding, or pressure may be applied successively to areas of the surface of the mat extending in one direction, e.g. by passing it between .crushing rolls. Crushable mats may be prepared by conventional wet lap methods, e.g. using a Fourdrinier machine, and, at any convenient stage, the mat may be impregnated (over selected areas only if desired) with 1 to 25% of one or more oils, e.g. drying oils of vegetable, animal or petroleum origin, or binding agents, e.g. asphalt, pine wood resin, polyvinyl acetate, phenol-formaldehyde resin, styrene-butadiene. The dried, stiff, board, having a moisture content less than 10%, preferably between 0.1 and 2.0%, of ¢-inch thickness, and density between 12 and 40 Ibs. per cu. ft. is crushed between rolls 13, 14, e.g. of 6-inch diameter, at a nip pressure of 10 to 15 lbs./sq. inch and then bent under an offset roll 19, rolls 10, 11, 15a and 16a supporting the mat. The operation may be restricted to selected areas and crushing and/or bending, in variable sequence, applied separately or simultaneously in one or more directions, preferably transverse to one another, to provide clearage planes 23a extending primarily parallel to the surface of the mat, which may, if desired, carry overlays of paper, cloth or plastic.