Patent ID: 7390846

Claim:
A process for providing composites of PVC and wood fiber having improved mechanical properties and thermal stability comprising the steps of: (A) dissolving a sizing agent comprising a polymer or copolymer comprising at least one alkali metal salt of at least one polymerized ethylenically unsaturated carboxylic acid in water to form an aqueous solution of the sizing agent; (B) adding wood fibers to the aqueous solution formed in (A); (C) separating and drying the wood fiber to a water content below 1%, whereby a coating of the water soluble sizing agent is formed on the surface of the wood fibers; (D) combining the sized wood fibers of (C) with PVC at elevated temperature to form composites comprising the sized wood fiber dispersed in a matrix of PVC having improved mechanical properties and thermal stability; wherein said polymer or copolymer is selected from the group consisting of alkali metal salts of: (1) poly(acrylic acid), poly(methacrylic acid), poly(crotonic acid), poly(maleic acid), or mixtures thereof; and (2) copolymers of acrylic acid, methacrylic acid, crotonic acid, or maleic acid with a comonomer selected from the group consisting of acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, acrylic acid esters, methacrylic acid esters, and styrene.