GB889050A - Process for the manufacture of polyurethanes - Google Patents

Abstract

Polyurethanes are made by reacting polyesters, polyester-amides and polyethers with tri-isocyanato-trisubstituted biurets of the general formula OCN.R1N(CONHR11NCO).CONHR111.NCO wherein R1, R11 and R111 are divalent hydrocarbon radicals. In Example 8, a polyester is made by reacting together pentaerythritol, 1,3-butylene glycol, adipic acid and phthalic anhydride. This polyester is mixed with water, a reaction-product of octyl phenol and ethylene oxide, and tri-beta-chlorethylphosphate; and to this mixture is added a tricyanato-trisubstituted biuret, made from 2,4-tolylene di-isocyanate (see Group IV(b)), and dissolved in excess of the diisocyanate. The mixture is vigorously stirred for 2 minutes and poured into a mould. Foaming took place with negligible loss of gas to give a cellular rigid product. In Example 9, a similar product is obtained by reacting the polyester with a tricyanato-trisubstituted biuret derived from 4,41-di-isocyanato-3-methyldiphenylmethane.ALSO:Tri-isocyanato-N,N1,N1 1-trisubstituted biurets of the general formula OCN.R1N(CONHR11NCO).CONHR111.NCO wherein R1, R11 and R111 are divalent hydrocarbon radicals, are made either by reacting organic di-isocyanates with not greater than one-third of a molar proportion of water, and completing the reaction at a temperature between 60 DEG C. and 200 DEG C., or by reacting organic diisocyanates with not more than one molar proportion of a di-isocyanato-urea. In either reaction, dibutyl tin dilaurate or mercury benzamide may be used as catalyst. In Example 1, a solution of water in acetone is added, at about 36 DEG C., to 2,4-tolylene di-isocyanate which is stirred under nitrogen. After about 3 hours at 36 DEG C., the mixture is raised to 155 DEG C. to 160 DEG C. during 1 hour, whilst removing acetone by distillation. The mixture is maintained at 155 DEG C. to 160 DEG C. for another 2 hours. The resulting approximately 30% solution of N,N1,N11 tri (isocyanato-tolyl) biuret in excess di-isocyanate contains 41% isocyanate groups. In Example 4, a mixture of bis-(3-isocyanato-4-methylphenyl)-urea and 2,4-tolylene di-isocyanate is stirred under nitrogen at 155 DEG C. to 160 DEG C. for 2 hours. The resulting tri-isocyanato-tri-substituted biuret solution contains 40% isocyanate groups. In Example 5, a 4,41 - di - isocyanato - 3 - methyldiphenylmethane composition (containing 32% NCO) is reacted with water, dissolved in acetone, to give a product containing 27% NCO. Other diisocyanates which may be used to make triisocyanato-trisubstituted biurets are: hexamethylene di-isocyanate, chloro- and methoxy-phenylene - 2,4 - di - isocyanates, 4,41 - di - isocyanato - diphenyl ether, and naphthylene di-isocyanates. The tri-isocyanato-trisubstituted biurets may be used to make polyurethane products (Group IV(a)).ALSO:Polyurethanes are made by reacting polyesters, polyester-amides and polyethers with tri-isocyanato-trisubstituted biurets of the general formula OCN.R1N(CONHR11NCO).CONHR111.NCO wherein R1, R11 and R111 are divalent hydrocarbon radicals. In Example 8, a polyester is made by reacting together pentaerythritol, 1,3-butylene glycol, adipic acid and phthalic anhydride. This polyester is mixed with water, a reaction-product of octyl phenol and ethylene oxide, and tri-beta-chlorethylphosphate; and to this mixture is added a tricyanato-tri-substituted biuret, made from 2,4-tolylene diisocyanate (see Group IV(b)), and dissolved in excess of the di-isocyanate. The mixture is vigorously stirred for two minutes and poured into a mould. Foaming took place with negligible loss of gas to give a cellular rigid product. In Example 9, a similar product is obtained by reacting the polyerster with a tricyanato-tri-substituted biuret derived from 4,41-di-isocyanato-3-methyldiphenyl-methane.