GB986521A - Improvements in or relating to the manufacture of polymeric materials - Google Patents

Abstract

A rigid polyurethane is prepared by reacting a hydroxypolyether with excess of a polyisocyanate to form a prepolymer and reacting the prepolymer with further hydroxypolyether and a liquid of boiling point below 75 DEG C., the hydroxypolyether having a molecular weight of 500-2000 and being a reaction product of sucrose and a cyclic oxide. Specified cyclic oxides are ethylene oxide, propylene oxide, butylene oxide and epichlorohydrin. Alkali used to catalyse the formation of the hydroxypolyether may be removed prior to prepolymer formation with fluorosilicic or acetic acid. In the latter case 0.1-1.0% benzoyl chloride should be added to the polyisocyanate. Specified polyisocyanates are: hexamethylene diisocyanate, tolylene 2:4 and 2:6 diisocyanate, m- and p-phenylene diisocyanate, chlorophenylene 2:4 diisocyanate, diphenylmethane 4:41 diisocyanate, 3-methyl-diphenylmethane 4:41 diisocyanate, 2:4:6 triisocyanato-toluene, and 2:4:41 triisocyanato-di-phenyl ether and mixture of polyisocyanates, e.g. that formed by phosgenation of the mixed amine product of interacting formaldehyde with an aromatic amine, e.g. aniline or O-toluidine. Prepolymer formation takes place at 15-100 DEG C. and 10-50% of the polyether is used. The foaming step may be a batch or continuous process and the hydroxypolyether used may be different from that used for prepolymer formation. The low boiling liquid is added to extent of 1-150% of polyether. Specified compounds are:-CCl3F, CCl2F2, CHCl2F, CHClF2, C2Cl2F4, CH2Cl2 and (CH3)2CO. Other additives may be:-catalysts, e.g. dibutyl tin dilaurate, stannous octoate, iron or manganese acetylacetonate, 46dimethylamino pyridine, triethylene diamine, N:N-dimethylbenzylamine, N:Ndimethylcyclohexylamine or N:N:N1:N1-tetramethylbutanediamine, surface active agents, e.g. siloxane/oxyalkene block copolymers, oxyethylated phenols, oxyethylated fatty alcohols or block copolymers of ethylene or propylene oxides which may contain tertiary nitrogen atoms, monomeric polyhydroxy compounds, foam stabilizers, e.g. ethyl cellulose, colouring, plasticizers, fire proofing agents, e.g. tri-b chloroethyl phosphate or antimony compounds and antioxidants, e.g. tert.-butyl cathechol. In examples 1 and 4 a sucrose-propylene oxide condensate prepared with pressure and heating by a KOH catalysed reaction is reacted with benzoyl chloride excess and 2:4/2:6 tolylene diisocyanate to give a prepolymer. This was foamed by adding CCl3F, a siloxane/oxyalkylene block copolymer, dibutyl tin dilaurate, tri-b -chloroethyl phosphate and further sucrose-propylene oxide condensate. In examples 2, 3, 5, 6, 7, 8 and 9 the sucrose-propylene oxide condensate used in the foaming step differed from that used for prepolymer formation. In examples 10 and 11 acetic acid was added to the condensate to neutralize the KOH catalyst. Specifications 891,776 and 892,557 are referred to.