GB1004924A - Improved polyurethane foam and method of making it - Google Patents

Abstract

A polyurethane foam is produced by reacting in the presence of a blowing agent a branched active hydrogen-containing synthetic resin (A) having not less than three active hydrogen containing groups to the molecule with a combined hydroxyl-acid number of at least 225, at least 75% of the active hydrogen groups being alcoholic hydroxyl groups, and an amount at least sufficient to react with all the said hydroxyl groups of a mixture (B) of methylene bridged polyphenyl polyisocyanates comprising diisocyanates, triisocyanates, and higher molecular weight polyisocyanates, substantially 45 to 60 parts per 100 parts by weight of said mixture being diisocyanates, the combined weight of diisocyanates and triisocyanates being substantially 60 to 75 parts per 100 parts by weight of said mixture, the remainder of the mixture having a sufficiently high average molecular weight that the average molecular weight of the total mixture is at least 381, said mixture having vixcosity less than or equal to 1090 centipoises at 25 DEG C. and an isocyanate equivalent of at least 127, said mixture of isocyanates having been formed by phosgenation of diamines, triamines and higher molecular weight polyamines formed by acid condensation of aniline and formaldehyde. The active hydrogen-containing material (A) may be a polyether, polyester or polyesteramide, many such materials are specified. In a typical Example (1) a polyesteramide derived from polymerized linoleic acid by reaction with polyamines and a trimethylol propane adipate polyester was reacted with the mixture of polyisocyanates in the presence of water and N-methyl morpholine to produce a polyurethane foam.ALSO:A mixture of methylene bridged polyphenyl polyisocyanates comprising diisocyanates, triisocyanates and higher molecular weight polyisocyanates, substantially 45 to 60 parts per 100 parts by weight of said mixture being diisocyanates, the combined weight of diisocyanates and triisocyanates being substantially 60 to 75 parts per 100 parts by weight of said mixture, the remainder of said mixture having a sufficiently high average molecular weight that the average molecular weight of the total mixture is at least 381, said mixture having a viscosity less than or equal t2 1090 centipoises at 25 DEG C. and an isocyanate equivalent of at least 127; is formed by phosgenation of diamines, triamines and higher molecular weight polyamines formed by acid condensation of aniline and formaldehyde.