Method of reclaiming water-based paint: U.S. Patent 5,560,860. Oct. 1, 1996 W.C. Walsh and L.E. James, assignors to BASF Corp., Mt. Olive, N.J.

Abstract

Polytetrafluoroethylene (PTFE) is a fluoropolymer and is commonly known by its trade name, Teflon®. Unique properties of PTFE include nonreactivity, hydrophobicity, a low coefficient of friction, and good insulating properties. It is most commonly used as a nonstick coating for cookware. PTFE is also used in the manufacture of semiconductors and medical devices; as coatings for bulk chemical containers, eyeglasses, and shaver blades; and as an inert ingredient of pesticides. PTFE is among the most chemically inert, nontoxic, and nonflammable substances tested under normal usage conditions, and is not metabolized. Although PTFE is not a skin irritant in rabbits or humans, or a skin sensitizer in humans, the major safety concern with PTFE is workplace exposure to its pyrolysis products, which may be irritating to the eyes, skin, and mucous membrane. PTFE pyrolysis products can also produce influenza-like symptoms (also known as ‘polymer-fume fever’). In nonclinical studies, no toxicologically significant effects were observed in rats administered 25% PTFE in the diet for 90 days. A persistent chronic inflammatory reaction that exhibited progressive tissue growth was noted at the injection site in mice, rabbits, and dogs administered a single injection of PTFE particulate in a glycerine carrier for up to 1 year. Localized fibrosarcomas have been reported with subcutaneous injection of PTFE sheets or discs in mice and rats. However, the International Agency for Research on Cancer has concluded that insufficient data exist to assess the carcinogenic risk of human exposure to PTFE. There are no known ecotoxicological effects of PTFE.