Production of hardboard
AssigneeUnited States Gypsum Company
InventorMyron M. Luszczak
Life of this patent
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Abstract
A process for improving the strengths and resistance to water absorption of wood fiber hardboard, along with a lessening in the number of conventional steps, is disclosed. Hardboad is thereby produced by a process wherein drying oil is added to the wood chips prior to the pulp preparation stage; and optionally an oxidation accelerator is added during the pulp preparation stage. The hardboard is then formed in the usual manner without requiring the conventional addition of binder ingredients in the stock chest, without requiring conventional baking following pressing and, in the case of "tempered" hardboard without requiring the subsequent addition of tempering materials and baking following the conventional press operation.
Claims9
An improved process for manufacturing wood fiber board characterized by eliminating the conventional baking step that follows pressing of the mat to board and by imparting additional strengths and water resistance to the formed board which comprises:
- (1) reducing a supply of wood to chips;
- (2) blending a small amount of drying oil with said chips, said drying oil ranging from about 0.5% to about 10% by dry weight of the wood chips;
- (3) steaming the treated wood chips in a closed vessel for a period of time from about 1 to 10 minutes and at a pressure between about 50 and 300 lbs. per square inch, whereby the drying oil is sorbed into the wood chips;
- (4) refining the wood chips whereby the treated chips are formed into fibers;
- (5) forming the fibers into an aqueous slurry pulp;
- (6) mechanically dewatering the pulp to obtain a wet mat;
- (7) drying the wet mat by thermal evaporization;
- (8) and pressing the dried mat between heated forming surfaces to form a hardboard.
An improved process for manufacturing wood fiber hardboard characterized in having a modulus of rupture of at least about 7,000 lbs. per square inch, and a tensile strength perpendicular to surface of at least about 150 lbs. per square inch, and further characterized by eliminating the conventional baking step after pressing of the mat to hardboard, which comprises:
- (1) reducing a supply of wood to chips;
- (2) blending a small amount of drying oil with said chips, said drying oil ranging in amount from about 0.5% to about 10% by dry weight of the wood chip feed;
- (3) steaming the treated wood chips in a closed vessel for a period of time from about 1 minute to about 10 minutes and at a pressure between about 50 and about 300 lbs. per square inch, whereby the drying oil is sorbed into the wood chips while the wood chips are being softened by such cooking;
- (4) refining the treated wood chips whereby the treated chips are fiberized;
- (5) forming the fibers into an aqueous slurry pulp;
- (6) adding to the aqueous fiber slurry a small amount of an oxidation accelerative agent for the drying oil;
- (7) mechanically dewatering the pulp to obtain a water mat;
- (8) drying the wet mat by thermal evaporization;
- (9) pressing the dry mat between heated forming surfaces to form a hardboard;
- and
- (10) humidifying the hardboard product to absorb from about 2 to 9% moisture by weight of the board and obtain a tempered hardboard product.
Dependencies are inferred from the claim text.