GB831301A - Reaction products of polyesters with polyisocyanates or polyisothiocyanates - Google Patents

Abstract

A process for the preparation of a stable reaction product of a polyester with a polyisocyanate or polyisothiocyanate comprises mixing with the reaction product within a short time of preparation thereof an oxyacid of phosphorus in an amount sufficient to retard cross-linking thereof. Suitable acids are orthophosphoric, metaphosphoric, pyrophosphoric, phosphorous and hypophosphorous acids. The amount is preferably 0.02 to 0.5% by weight of the reaction product. The acids may be used in conjunction with cyclic or acyclic acid chlorides, acid esters of phosphorus-containing acids and/or nitro derivatives of aromatic sulphenyl halides, for example, mixtures of orthophosphoric acid a p-nitrobenzoyl chloride; phosphorous acid and fumaryl chloride; pyrophosphoric acid and butyl hydrogen phosphate; orthophosphoric acid and ortho-nitrobenzenesulphenyl chloride. Preferably reaction products of linear polyesters are employed and there may also be used cross-linking agents such as water, polyvalent alcohols, polyvalent amines, e.g. o,o1-dichlorobenzidine or p-phenylenediamine, guanidine or amino-alcohols. Before moulding the acid in the compositions is neutralized, by incorporating (by milling) either an excess of cross-linking agent (when this is of a basic character) or such materials as diphenylamine, para-phenylenediamine, diphenylguanidine, guanidine, aniline, benzidine, o,o - dichlorobenzidine, anisidine, amino-pyridine, 2 - 2 - dipyridylamine, 2 - amino - 4 : 6 - dimethylpyridine, hexamethylene tetramine, hydrazine hydrate, magnesium oxide, calcium hydroxide and ammonium carbonate. Additional polyisocyanate to bring the ratio of polyester from 1:1.01 to 1:1.10 up to between 1:1.4 and 1:1.6 may be milled in at the same time. Carbon black, silica or other fillers can also be incorporated. Specifications 790,543, 791,956 and 831,302 are referred to.