Patent ID: 8686058

Claim:
A process for preparing a viscoelastic polyurethane foam, comprising: A) forming a reaction mixture including: a) an isocyanate reactive component comprising a polyol composition of: a1) from 30 to 80 wt % of a combination of a polyoxypropylene based polyol and a polyoxyethylene-polyoxypropylene polyol that is different from the polyoxypropylene based polyol, each of the polyoxypropylene based polyol and the polyoxyethylene-polyoxypropylene polyol having an average nominal hydroxyl functionality of 2-4 and an average equivalent weight between 100 and 2000, the polyoxypropylene based polyol having a polyoxypropylene content of at least 85 wt % based on a total weight of the polyoxypropylene based polyol, and the polyoxyethylene-polyoxypropylene polyol having a polyoxypropylene content of at least 70 wt % based on a total weight of the polyoxyethylene-polyoxypropylene polyol; a2) from 5 to 50 wt % of a polyoxyethylene containing polyol having an average nominal hydroxyl functionality of 2-4 and an average equivalent weight between 100 and 1000, the polyoxyethylene containing polyol having an average nominal hydroxyl functionality of 2-4 and an average equivalent weight between 100 and 1000, the polyoxyethylene containing polyol having a polyoxyethylene content of at least 70 wt % based on a total weight of the polyoxyethylene containing polyol; and a3) from 1 to 40 wt % of at least one isocyanate reactive compound derived from a renewable natural resource; b) a polyisocyanate component, c) water in an amount of 0.5 to 3.5 weight percent of a), and d) optional additives and auxiliaries; and B) subjecting the reaction mixture to conditions sufficient to cause the reaction mixture to expand and cure to form a viscoelastic polyurethane foam having a resiliency of less than 20% as measured according to the ATSM D-3574-H ball rebound test.