GB701238A - Improvements in the production of polyurethanes - Google Patents

Abstract

Polymethanes are prepared by reacting a diamine and a bischloroformate in a dispersion of a solution of the bischloroformate in a water immiscible solvent and an aqueous solution of the diamine, and in the presence of a water miscible solvent such as a ketone, alcohol, glycol, glycerol, glycol ether, glycol ether-ester, diacetone alcohol, acetonyl acetone, and dioxane. The water miscible solvent is preferably added to the diamine solution before dispersion with the bischloroformate solution, from 10-100 parts of water-miscible solvent being used per 100 parts of water. Aromatic hydrocarbons are preferred as the water immiscible solvent as these give higher molecular weight products. Diamine may be used as the alkaline reagent to bring about the polymerization but preferably the process of Specification 683,504 is used, the diamine being present as the hydrochloride and an alkaline material added to bring about the reaction. Preferred figures are given for the volume ratio of the two phases and the concentration in each phase. The Specification lists suitable diamines, bischloroformates, alkaline substances and emulsifying agents. In examples (1) tetramethylene diamine hydrochloride dissolved in a mixture of water and acetone and butane diol bischloroformate in toluene were dispersed and aqueous sodium hydroxide added, the temperature being kept at 0-2 DEG C. A 73 per cent. yield of 4.4 polymethane was obtained. Without acetone the yield was 52 per cent.; (2) As in (1) using N-lauroyl-N-butyl taurine as emulsifying agent and a temperature of -2 to 2 DEG C.; yield 89 per cent.; (3) As in (2) using ethylene glycol instead of acetone and a temperature of -5 to -6 DEG C.; yield 85 per cent.; (4) As in (3) using glycerol instead of glycol; yield 87 per cent.