GB858757A - Synthetic rubber-like materials - Google Patents

Abstract

A process for the manufacture of synthetic rubber-like materials by reacting organic diisocyantes with polyesteramides, is characterized in that the said reaction is carried out under substantially anhydrous conditions and that the polyesteramide is based on dicarboxylic acid, glycol and diamine and/or aminoalcohol in such proportions that from 8 to 64 mols. of dicarboxylic acid are present for each mol. of primary amino group and the polyesteramide is crystalline with a melting point not exceeding 50 DEG C and has a water content of not more than 0,1% by weight and an acid value of not more than 5 mg. KOH per gm. and preferably not more than 3 mg. KOH per gm. The process may be effected in one step by mixing the polyesteramide and all the diisocyanate, casting and heating in a mould. Preferably a "raw rubber" is produced in a first stage by reacting such an amount of diisocyanate as to give a processible reaction product with a Williams Plasticity Number between 200 and 550. The "raw rubber" is then processed with an organic polyisocyanate and there may also be incorporated fillers such as carbon black, silica, china clay, calcium carbonate, titanium dioxide, aluminium silicate and fibres such as those of glass, polyesters, polyamides, wool and ground leather, plasticizers, catalysts, acids such as adipic and stearic and materials capable of forming adducts with isocyanates. Curing is then effected with heating and pressure. In a typical Example (12) a "raw rubber" of Williams Plasticity Number 289 is prepared by reacting mixed toluene -2,4 and 2,6- diisocyanates with a polyesteramide prepared by reacting adipic acid, ethylene glycol, diethylene glycol and ethanolamine. It is milled with stearic acid, silica and 4:41 diisocyanate -3- methyldiphenylmethane and press cured at 150 DEG C.