Patent ID: 6919384

Claim:
A process for preparing a flexible polyurethane foam comprising reacting: (a) a polyisocyanate-terminated prepolymer consisting of the reaction product of: (i) 80-100% by weight of a diphenylmethane diisocyanate comprising at least 40% by weight of 4,4′-diphenylmethane diisocyanate and/or a derivative of said diphenylmethane diisocyanate that is liquid at 25° C., (ii) 20-0% by weight of another polyisocyanate, (iii) a first polyether polyol having an average nominal functionality of 2-8, an average equivalent weight of 750-5000, an average molecular weight of 2000-12000, and an oxyethylene content of 50-90% by weight, and (iv) a second polyether polyol having an average nominal hydroxyl functionality of 2-8, an average equivalent weight of 750-5000, an average molecular weight of 2000-12000, and an oxyethylene content of 0-25% by weight, wherein, the first polyether polyol and the second polyether polyol are used in a weight ratio of from 30:70 to 70:30 and (b) an isocyanate-reactive composition consisting of: (i) 80-100% 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, and an oxyethylene content of 50-90% by weight, and (ii) 20-0% by weight of one or more other isocyanate-reactive compounds other than water; in the presence of water, wherein the reaction is conducted at an isocyanate index of 70 to 120 and the polyisocyanate-terminated prepolymer has a NCO value of 5-30% by weight.