Patent ID: 6579912
Filing Date: 2003-06-17
Classification: C08G

Abstract:
A process for preparing a flexible polyurethane foam having an apparent overall density of 15-150 kg/m3 comprising the step of reacting a polyisocyanate and an isocyanate-reactive composition in the presence of water, wherein the reaction is conducted at an isocyanate index of 50 to 130, and the polyisocyanate comprises:a) 80-100% by weight of a diphenylmethane diisocyanate comprising at least 40% by weight of 4,4â€²-diphenylmethane diisocyanate and/or a derivative of said diphenylmethane diisocyanate, which derivative has an NCO value of at least 20% by weight, and b) 20-0% by weight of another polyisocyanate and the isocyanate-reactive composition comprises: a) 10-100% by weight of a polyether polyol having an average nominal functionality of 2-8, an average equivalent weight of 750-5000, an average molecular weight of 2000-12000, an oxyethylene content of 20-90% by weight calculated on the weight of the polyether polyol, a melting enthalpy, |&Dgr;Hm|, of at least 30 J/g and a melting temperature, Tm, of 4Â° C. or more, excluding such polyols having an oxyethylene content of 60-90% by weight and a primary hydroxyl content of 70-100% and excluding such polyols having an oxyethylene content of at least 50% by weight and being random polyoxyethylene polyoxypropylene polyols, and b) 90-0% by weight of one or more other isocyanate-reactive compounds excluding water.