POLYISOCYANATE COMPOSITION FOR SOFT POLYURETHANE FOAM AND PROCESS FOR PRODUCING SOFT POLYURETHANE FOAM FROM THE COMPOSITION

摘要

[PROBLEMS] To provide a soft polyurethane foam having a favorable storage stability and being simultaneously favorable in rebound resilience and mechanical properties. [MEANS FOR SOLVING PROBLEMS] There is provided a polyisocyanate composition for soft polyurethane foam obtained by performing a urethanization reaction of pure MDI (a) with an equivalent amount or less of polyol (b) under the following conditions and thereafter mixing a polymeric MDI (c) with the reaction product. (2,2'-MDI + 2,4'-MDI)/MDI = 60 to 85 mass%, and MDI/((a) + (C)) = 50 to 90 mass% provided that the component (b) is a polyether polyol of 700 to 10,000 number average molecular weight, 2 to 8 functional groups on average and 10 to 40% in the content of oxyethylene in the repeating units.