There are at present a large number of products which are formed with wood or use wood, plywood or the like as a structural component, substructure, or base to provide the requisite physical properties such as tensile and structural strength, rigidity and shape to which surface attachments, covers, or coatings can be screwed, nailed, glued or otherwise fastened, applied or attached.
Typical examples include insulated steel doors which use a perimeter frame of wood to which steel sheeting is applied on opposite sides thereof and the frame then filled with foamed insulation.
Other examples include wood door and window frame profiles whose exposed surfaces may be painted, covered or clad, for instance, with plastic or aluminium, or wood clad door panels used in folding or swing doors for garages or for truck or other vehicle doors and the like.
With such present products, the physical properties of the available components or substructures are relatively limited being determined by the selection of the wood, plywood or other board which is produced by conventional manufacturing processes.
Moreover, substantial wastage of wood by splintering, warping or by virtue of imperfections occurs in the manufacturing processes, and often the final product is subject to water absorption, warping, delamination and rotting.
Further, if other than conventional regular shapes of such materials, such as square or rectangular, are required for their end use, such shapes must be fabricated by sawing, cutting and/or assembling individual pieces and securing them together with nails, screws or other fastening means.
Composite materials which can be molded or processed into products have been proposed. For example, U.S. Pat. No. 5,075,057, issued Dec. 24th, 1991, discloses producing a product in which scrap plastic material containing some themoplastic material is shredded, milled and homogenized into a free flowing powder which is then warmed by subjecting same to heat to a temperature below the softening temperature of the plastic. This heated free flowing powder is then dry blended with filler material which preferably is heated or pretreated, eg. with chemicals. The dry blend is then compression molded at elevated temperatures and pressures.
U.S. Pat. No. 4,003,866, issued Jan. 18th, 1997, discloses a construction material comprising a plastic component containing a thermoplastic resin and a filler component. These components are mixed together under the application of heat. To improve the adhesion between the plastic material and the filler material, such as wood wastes, the particles of filler material before being mixed with the plastic are precoated under the application of heat tumbling with the polyethythlene or polypropylene wax having a molecular weight of from 1,000 to 10,000, a thermofluid high molecular weight polymer, or a silicate coating material.
Such prior art materials involving the various mixing, heating and coating steps are relatively expensive to produce and an adequate intimacy of bond between the plastic and filler is difficult to achieve.