Patent ID: 7291661

Claim:
A non-staining polymer composite product, comprising: a polymer matrix combined with a filler and a cellulosic material; the filler comprising calcium carbonate capable of reaction with tannin to produce a stain on the surface of the product, and the cellulosic material comprising tannin molecules, wherein some of the tannin molecules would be susceptible to leaching from the cellulosic material due to the product coming into contact with moisture, to make available leached tannin molecules for reaction with the calcium carbonate to produce the stain; and a compound combined in the product with the polymer matrix, the filler and the cellulosic material, the compound comprising at least two functional groups for reaction with one or more hydroxyl groups present in the tannin molecules, wherein at least some of the compound reacts with at least some of the tannin molecules to prevent such tannin molecules from being made available as leached tannin molecules for reaction with the calcium carbonate to produce the stain.