Preparation of soft polyurethane foam

PURPOSE: To obtain a low-density foam in one shot without using a halocarbon blowing agent by adding water and specific isocyanate reactive compds. to methylene diphenyl isocyanates and foaming the mixture. CONSTITUTION: The objective foam is obtd. by compd. (B) the isocyanate reactive compds. (e.g. polyether polyol of ethylene oxide, etc.), such as polyols and polyamides, having a functionality of 2 to 4 and an average equiv. weight of 750 to 5,000 and (C) the water with (A) the methylene diphenyl isocyanates in such a manner that the isocyanate index expressed by formula attains 10 to 60 and the weight rat of the component B: the component C attains ≤20. COPYRIGHT: (C)1989,JPO