GB1189997A - Polyether-Urethanes - Google Patents

Abstract

1,189,997. Polyetherurethanes. PFIZER Ltd. 27 Sept., 1967 [28 Sept., 1966], No. 43233/66. Headings C3C and C3R. Liquid polyetherurethane prepolymers having a free isocyanate content are prepared by reacting, in the absence of a catalyst: (A) an aromatic diisocyanate; (B) a linear, liquid alpha-omega glycol having an hydroxyl equivalent weight below 250; and (C) a liquid polyoxyalkylene triol having an hydroxyl equivalent weight of at least 250, the ratio of isocyanate groups in (A) to hydroxyl groups in (B) plus (C) being greater than one and the proportion of triol (C) to glycol (B) being such that the reaction product is a stable liquid, i.e. a liquid which does not crystallize within 24 hours at ambient temperatures. The compounds (A), (B) and (C) are those conventionally used in the art. Especially preferred as glycol (B) is diethylene glycol which may be used such that the weight ratio of triol (C) to diethylene glycol is at least 4 to 1, preferably 6 to 1. The reaction between (A), (B) and (C) is preferably carried out at temperatures of 55‹ to 90‹ C. Elastomers may be prepared from the prepolymers by reaction with further amounts of glycol (B) and/or triol (C) in the presence of an organometallic catalyst such that the ratio of isocyanate groups to hydroxyl groups is in the range of 0À95 to 1 to 1À2 to 1. Alternatively the prepolymer may be reacted with other compounds containing two or more hydroxyl and/or primary amine groups or may be dissolved in a solvent with a tertiary amine catalyst and allowed to cure by reaction with moisture in the atmosphere. Microcellular elastomers may be prepared from the prepolymers by reaction with further amounts of (B) and/or (C) in the presence of small amounts of air and/or water and, if desired, a nucleating agent. The additional triol (C) may be partially or entirely replaced by an inert plasticizer such as phthalic acid esters and chlorinated hydrocarbons. Numerous examples are given of the polyetherurethane prepolymers and elastomers prepared therefrom.