Abstract: A method to prepare polyurethane and/or polyurea flexible foams which comprises reacting:A. an organic polyisocyanate compositionB. an isocyanate-reactive composition containing:a. at least one high Mw isocyanate-reactive compoundb.sub.1. a primary or secondary amino-functional compound (so-called chain-extender) of Mw below 1000 in an amount of less than 1% by wt of high Mw isocyanate-reactive compound(s) orb.sub.2. a mixture of at least two chain extenders of which at least one is a primary or secondary amino-functional compound of Mw below 1000, in an amount of 0.1% to 10% by wt of high Mw isocyanate-reactive compound(s)C. H.sub.2 OD. optionally catalystsE. optionally further blowing agents which are different from H.sub.2 O.F. optionally further conventional additives.

Abstract: A method to prepare polyurethane and/or polyurea flexible foams which comprises reacting:A. an organic polyisocyanate compositionB. an isocyanate-reactive composition containing:a. at least one high Mw isocyanate-reactive compoundb.sub.1. a primary or secondary amino-functional compound (so-called chain-extender) of Mw below 1000 in an amount of less than 1% by wt of high Mw isocyanate-reactive compound(s) orb.sub.2. a mixture of at least two chain extenders of which at least one is a primary or secondary amino-functional compound of Mw below 1000, in an amount of 0.1% to 10% by wt of high Mw isocyanate-reactive compound(s)C. H.sub.2 OD. optionally catalystsE. optionally further blowing agents which are different from H.sub.2 O.F. optionally further conventional additives.