NON-CELLULAR POLYURETHANES

1,218,360. Non-cellular polyurethanes. IMPERIAL CHEMICAL INDUSTRIES Ltd. 15 May, 1968 [11 July, 1967], No. 31893/67. Heading C3R. [Also in Division C2] Non-cellular polyurethanes are prepared by reacting a polyether with a stoichiometric excess of a diarylmethane diisocyanate composition obtained by reacting aniline or a mono-substituted nuclear derivative or mixture thereof with formaldehyde, there being an excess of the amine(s) in the reaction mixture, freeing the resultant mixture from unreacted starting material and reacting the resultant polyamine mixture with phosgene to convert the amino groups to isocyanate groups, and subsequently curing the resultant prepolymer by reaction with an aliphatic polyol. The preferred diisocyanate compositions are those prepared by reacting formaldehyde and aniline in a molar ratio of 1: 1À5 to 1: 5 in the presence of a Lewis acid, followed by separation of unreacted starting material and phosgenation. Polypropylene ether glycols of M.W. 500 to 4000 are the preferred polyethers. The aliphatic polyol may be a polyhydric alcohol, secondary or tertiary amino alcohols, polypropylene glycols or oxypropylated glycerols.