Patent ID: 6740687
Filing Date: 2004-05-25
Classification: B29C,B29K,C08G

Abstract:
A method for producing a flexible, high resilience polyurethane foam, comprising the steps of:(1) preparing a reaction mixture comprising: (a) a polyol mixture of (i) about 85 to 95 percent by weight total polyols of a polyether polyol having from 10 to 30 percent ethylene oxide groups, and having a hydroxyl number in the range of about 25 to 50 and a functionality from 2.5 to 3.5, and (ii) about 5 to 15 percent by weight total polyols of a graft polyol having a ratio of styrene to acrylonitrile of about 70 to 30, and having a hydroxyl number in the range of about 25 to 50 and a functionality from 2.5 to 3.0; (b) an organic polyisocyanate selected from the group consisting of toluene diisocyanate, and methylene diisocyanate mixed with toluene diisocyanate, wherein at least 50 percent of the methylene diisocyanate is 4, 4â€² methylene diisocyanate, wherein if a mixture of methylene diisocyanate and toluene diisocyanate is used, the polyisocyanate mixture comprises from about 5 to 20 percent by weight toluene diisocyanate and about 80 to 95 percent by weight methylene diisocyanate, and wherein the isocyanate index is in the range of 80 to 95; and (c) from about 1.8 to 2.8 parts per hundred parts polyol of water as a blowing agent; and (2) allowing said reaction mixture to react while held at a pressure of about 0.6 to 0.95 bar (absolute) so as to form the polyurethane foam; wherein said polyurethane foam has a density in the range of about 2 to about 3 pounds per cubic foot.