# US 5,718,786 A · Flat oriented strand board-fiberboard composite structure and method of making the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,718,786 A - Document ID: US5718786A - Status: Granted - Kind: A - Application number: 08/480,439 - Filed: 1995-06-07 - Granted: 1998-02-17 - Earliest claimed: 1990-04-03 - Assignees: Masonite Corporation - Inventors: Craig R. Lindquist; John T. Clarke; Peter P.S. Chin; Michael J. MacDonald; J. Peter Walsh - Web page: https://patentgrep.com/patent/US5718786A ## CPC - E04C 2/10: of wood, fibres, chips, vegetable stems, or the like; of plastics; of foamed products ({E04C2/049}, E04C2/26 take precedence; {hydraulic cement and mineral fibres E04C2/04}) - B27N 3/04: from fibres - B32B 5/12: characterised by the relative arrangement of fibres or filaments of {different layers, e.g. the fibres or filaments being parallel or perpendicular to each other} - E04D 1/205: {of wood} - B29K 2311/14: Wood, e.g. woodboard or fibreboard - Y10T 428/24058: including grain, strips, or filamentary elements in respective layers or components in angular relation - Y10T 428/24066: Wood grain - Y10T 428/24091: with additional layer[s] - Y10T 428/24116: Oblique to direction of web - Y10T 428/24554: including cellulosic or natural rubber component - Y10T 428/24595: and varying density - Y10T 428/24603: Fiber containing component - Y10T 428/24942: including components having same physical characteristic in differing degree - Y10T 428/2495: Thickness [relative or absolute] - Y10T 428/24992: Density or compression of components - Y10T 428/253: Cellulosic [e.g., wood, paper, cork, rayon, etc.] - Y10T 428/266: of base or substrate - Y10T 428/31989: Of wood - E04C: STRUCTURAL ELEMENTS; BUILDING MATERIALS (for bridges E01D; specially designed for insulation or other protection E04B; elements used as building aids E04G; for mining E21; for tunnels E21D; structural elements with broader range of application than for building engineering F16, particularly F16S) - B27N: MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL (containing cementitious material B28B; shaping of substances in a plastic state B29C; fibreboards made from fibrous suspensions D21J; drying F26B17/00) - B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM - E04D: ROOF COVERINGS; SKY-LIGHTS; GUTTERS; ROOF-WORKING TOOLS (coverings of outer walls by plaster or other porous material E04F13/00) - B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract An oriented strand board (OSB)-fiberboard composite structure is comprised of a baseboard having three wood strand layers, the wood strands being oriented in space with respect to a board forming machine such that a core layer is comprised of wood strands oriented generally in a random or cross-machine direction and each adjacent layer is comprised of coarse and fine wood strands oriented generally in the machine direction. In a preferred embodiment, the wood strands comprising each adjacent OSB layer are formed with the coarsest strands located nearest the core layer and the finest strands are located nearest the outer surfaces of each outer board layer. The OSB-fiberboard composite product is clad with a wood fiber overlay on one major surface of the baseboard. The composite board is manufactured without warping, by providing particular OSB layer thicknesses, such that the lower OSB layer is about 25% to about 35% thicker than the OSB layer bonded to the fiberboard. ## Claims ### Claim 1 A method of manufacturing a non-warping oriented strand board-fiberboard composite structure comprising: forming a baseboard having a top layer of machine-direction oriented wood strands; a central core layer of wood strands oriented perpendicularly to the top layer of wood strands or oriented randomly; and a bottom layer of wood strands oriented in the same direction as the top layer of wood strands, such that the bottom layer of wood strands, after consolidation, is about 25% to about 35% thicker than the top layer of wood strands, and the core layer, sandwiched between the top and bottom layers, comprises about 25% to about 35% of the thickness of the baseboard; disposing a fiberboard overlay mat over the top layer of the baseboard; and consolidating the fiberboard mat and the baseboard layers simultaneously in a heated press. ### Claim 2 (depends on 1) The method of claim 1, wherein said wood strands are comprised of flakes and slivers having a specific gravity of about 0.45 to about 0.60 having a moisture content of about 1% to about 15% by weight, based on the dry fiber weight. ### Claim 3 (depends on 1) The method of claim 1, wherein the wood fiber overlay layer is dry-felted and preformed separately from the baseboard and thereafter and transferred onto the baseboard as a mat prior to pressing the baseboard and the mat simultaneously under heat and pressure. ### Claim 4 (depends on 1) The method of claim 1, wherein the wood fiber overlay layer is wet-formed and preformed separately from the baseboard and thereafter transferred onto the baseboard as a mat prior to pressing the baseboard and the mat simultaneously under heat and pressure. ### Claim 5 (depends on 1) The method of claim 1, wherein the wood strands are bonded with a resin selected from the group consisting of phenol formaldehyde resin and polydiphenylmethyl diisocyanate resin and wherein the resin is added to the strands in an amount of about 2% to about 10% by weight of the dry weight of strands. ### Claim 6 (depends on 3) The method of claim 3, wherein the dry-felted wood fiber overlay layer is bonded with a resin selected from the group consisting of phenol formaldehyde resin, polydiphenylmethyl diisocyanate resin and mixtures thereof in an amount of about 2% to about 10% by weight, based on the dry fiber weight. ### Claim 7 (depends on 1) The method of claim 1, wherein the strands are sized with a hydrocarbon wax selected from the group consisting of paraffinic wax, microcrystalline wax and mixtures thereof in an amount of about 0.5% to about 2% by weight of the dry weight of the wood strands. ### Claim 8 (depends on 1) The method of claim 1, wherein the overlay wood fibers are sized with a hydrocarbon wax selected from the group consisting of paraffinic wax, microcrystalline wax and mixtures thereof in an amount of about 0.5% to about 4% by weight of the dry weight of fibers. ### Claim 9 (depends on 1) The method of claim 1, wherein the basis weight of the oriented strand baseboard is in the range of about 1,000 pounds/thousand square feet to about 2,000 pounds/thousand square feet. ### Claim 10 (depends on 1) The method of claim 1, wherein the composite structure is hot pressed between two heated dies thereby conforming both the oriented strand board layers and the fiberboard layer to a predetermined shape including deep embossing of the fiberboard layer including sharp outside corners in the fiberboard overlay layer, while contouring the oriented strand baseboard layers and maintaining near uniform density in the baseboard. ### Claim 11 (depends on 1) The method of claim 1, wherein the composite structure is hot pressed between two heated dies to selectively densify specific regions of the board thereby enhancing machinability of the product in said specific regions and increasing resistance to water entry into the densified regions. ### Claim 12 (depends on 1) The method of claim 1, wherein all layers of the composite structure are consolidated under heat and pressure in a single press cycle. ### Claim 13 (depends on 1) The method of claim 1, wherein the top fiberboard layer is preformed separately from the strand board layers such that the wood fibers of the top layer are of sufficient length to provide interlocking of fiberboard fibers for handleability so that the preformed fiberboard can be positioned onto the first oriented strand board layer prior to pressing all layers simultaneously under heat and pressure. ### Claim 14 (depends on 1) The method of claim 1, wherein the wood strands are formed with the coarsest strands farthest from the fiberboard layer. ### Claim 15 (depends on 1) The method of claim 1, wherein the thickness of each strand board layer is related as follows: ______________________________________ first strand board layer = 27.7-33.3% of total thickness of strand board layers core strand board layer = 25-35% of total thickness of strand board layers bottom strand board layer = 36.1-43.1% of total thickness of strand board layers, ______________________________________ and wherein the bottom strand board layer is about 25% to about 35% thicker than the first strand board layer. ### Claim 16 (depends on 15) The method of claim 15, wherein the top fiberboard layer has a thickness about 50% to about 125% the thickness of the core layer. ### Claim 17 (depends on 3) The method of claim 3 wherein the basis weight of the dry-felted fiberboard overlay is in the range of about 75 pounds/thousand square feet to about 400 pounds/thousand square feet.