GB980021A - Production of polymers - Google Patents

Abstract

A process for the production of a polyurethane prepolymer comprises reacting in the presence of a catalyst an organic polyisocyanate or polyisothiocyanate with a polymer of an alkylene oxide which when first formed has terminal secondary hydroxyl groups but in which these groups have been reacted with ethylene oxide. Little or no heating is necessary in the preparation. The prepolymer may be converted to a foamed material by addition of water and catalysts. Catalysts specified for the prepolymer formation are tertiary amines, preferably triethylene diamine, and esters, alkyl esters and salts of metals of Group IV, V and VI of the Periodic System. For the foaming step trimethylamine, triethylamine, N-methylmorpholine, N-ethylmorpholine, dimethylbenzylamine and organometallic compounds are suitable catalysts. Silicone oils and water-soluble copolymers of polydimethyl-siloxane and alkylene oxides may also be added. The polymer of alkylene oxide may be a linear polymer of propylene or butylene oxide or may alternatively be a copolymer of these oxides with a polyhydric alcohol such as glycerol, hexanetriol or trimethylol propane. These polymers, containing terminal secondary hydroxyl groups to replace such groups by terminal primary hydroxy groups. Preferably the addition of not less than 1 and not more than 4 ethylene oxide units to each hydroxyl group of the initial propylene or butylene oxide polymer or copolymer is effected. In examples (1) a prepolymer is prepared by mixing an ethylene oxide tipped, glycerol-centred propylene glycol of M.W. 3000, triethylene diamine and a mixture of tolylene-2,4 and 2,6-diisocyanates which is reacted in three portions; (2) a foamed product is obtained when the prepolymer is mixed, in a continuous foaming machine, with a silicone oil and an aqueous solution of N-methylmorpholine and triethylamine.