Polyurethane foams for comfort applications

A method of making a flexible polyurethane foam, comprising

• A. forming a reaction mixture by mixing:
• a) an isocyanate mixture comprising
• a-1) a first isocyanate-functional prepolymer, which first isocyanate-functional prepolymer is a reaction product of at least one hydroxyl-terminated polymer of ethylene oxide and optionally a hydroxyl-functional branching agent and/or a hydroxyl-functional chain extender with an excess of diphenylmethane diisocyanate of which diphenylmethane diisocyanate at least 50 weight-% is 4,4′-diphenylmethane diisocyanate,
• a-2) optionally diphenylmethane diisocyanate, wherein components a-1) and a-2) together have an isocyanate content of 5 to 15% by weight and contain 30 to 75 weight percent of oxyethylene units, based on the combined weight of components a-1) and a-2), and components a-1) and a-2) together constitute 40 to 60% of the total weight of the isocyanate mixture,
• a-3) a second isocyanate-functional prepolymer, which second isocyanate-functional prepolymer is a reaction product of at least one hydroxyl-terminated polymer of ethylene oxide and a hydroxyl-functional branching agent having at least three hydroxyl groups per molecule and a hydroxyl equivalent weight of up to 250 g/equivalent with an excess of toluene diisocyanate, and
• a-4) optionally toluene diisocyanate, wherein a-3) and a-4) together have an isocyanate content of 5 to 15% by weight and contain 30 to 75 weight percent of oxyethylene units, based on the combined weight of components a-3) and a-4) and 2 to 5% by weight of residues from the hydroxyl-functional branching agent, based on the combined weight of components a-3) and a-4);
• components a-3) and a-4) together constitute 40 to 60% of the total weight of the isocyanate mixture;
• and components a-1), a-2), a-3) and a-4) together constitute the entire weight of the isocyanate mixture;
• b) water;
• c) at least one polymer polyol comprising polymer particles dispersed in at least one base polyol, the base polyol being a polyether having at least 50% by weight oxypropylene units and a hydroxyl equivalent weight of 500 to 3000 g/equivalent;
• d) optionally a poly(ethylene oxide), the poly(ethylene oxide) being a homopolymer of ethylene oxide homopolymer or a random and/or block copolymer of at least 80% by weight ethylene oxide and up to 20% by weight of another alkylene oxide, the poly(ethylene oxide) having a number average molecular weight of 400 to 1200 g/mol;
• at least one of e) and f), wherein e) is at least one silicone surfactant;
• and f) is at least one ethylene oxide/higher alkylene oxide block copolymer, the block copolymer containing 40 to 90% by weight oxyethylene units and having a number average molecular weight of 1500 to 12,000 g/mol;
• and optionally
• g) at least one phase change material that has a melting or glass transition temperature of 25 to 37° C. and which does not contain isocyanate groups or isocyanate-reactive groups;
• wherein
• i) the isocyanate mixture constitutes 40 to 65% of the combined weights of components a-g;
• ii) water constitutes 15 to 41% of the combined weights of components a-g;
• iii) the at least one polymer polyol constitutes 8 to 20% of the combined weights of components a-g and the polymer particles constitute 0.5 to 10% of the combined weights of components a-g;
• iv) the poly(ethylene oxide) when present constitutes up to 5% of the combined weights of components a-g;
• v) the at least one silicone surfactant constitutes 0 to 3% of the combined weights of components a-g;
• vi) the at least one ethylene oxide/higher alkylene oxide block copolymer constitutes 0 to 3% of the combined weights of components a-g;
• vii) the at least one phase change material constitutes up to 15% of the combined weights of components a-g and
• viii) components a-g constitute at least 95% of the weight of the reaction mixture and
• B. reacting the reaction mixture to produce the foam.