GB783615A - Diisocyanate-modified polyesters and rubber-like materials derived therefrom - Google Patents

Abstract

A material convertible into a rubber is made by reacting a molar excess of a diisocyanate with a polyethylene glutarate of molecular weight at least 1000 and preferably 3000 to 7000. Reaction may be effected in two stages in the first of which less than an equivalent amount of diisocyanate is used and in the second of which additional diisocyanate is dispersed in the composition. A small amount of water may be present during the reaction and the reaction may be moderated by adding acidic materials, e.g. sulphur dioxide, boric acid, adipic acid, salicylic acid or butadiene sulphone (which decomposes into butadiene and sulphur dioxide). The diisocyanate modified polyester may be converted into a rubber (a) by heating it with a basic catalyst, e.g. lithium, sodium, potassium, beryllium, magnesium, calcium or barium hydroxide; sodium methoxide or ethoxide; or pyridine, trimethylamine, triethylamine, tripropylamine, tributylamine, triamylamine, tribenzylamine or dimethylaniline and/or (b) by heating with a cross-linking agent, e.g. water, glycerol, triethanolamine, ethylene glycol, 1 : 3-propane diol, 1 : 4-butane diol, ethylene diamine, trimethylene diamine, tetramethylene diamine, m-phenylene diamine, o- or m-dichlorobenzidine, dianisidine, 4,41-diamino-diphenyl methane, naphthylene diamines, tolylene 2,4-diamine, p-aminobenzyl aniline, o- or p-aminodiphenyl-amine, 2-amino ethyl alcohol, 2-amino1 - naphthol, m - aminophenol, glycollic acid, alpha-hydroxy propionic acid, amino acetic acid and amino benzoic acid. When water is used as cross-linking agent it may be added in the form of a salt containing water of crystallization, e.g. cobaltous chloride hexahydrate or the diisocyanate modified polyester may be made to take up water by heating it in an oven having an atmosphere of low humidity or by exposing it to the atmosphere. After adding the catalyst or cross-linking agent the composition may be converted into chips, ribbons, films, sheets, fibres, filaments, solutions or dispersions. When the composition is fluid and a cross-linking agent giving rise to evolution of a gas is used (e.g. water or steam), an expanded material may be obtained by heating in a suitable mould. The cross-linking reaction may be controlled by methods described in Specifications 767,017 and 773,991. Carbon black may be added to the reactants during the preparation of the rubber.