GB842734A - Improvements in or relating to the manufacture of cellular polymeric materials - Google Patents

Abstract

Cellular polymeric materials are manufactured by interacting a hydroxy-ended polytetrahydrofuran, a polyisocyanate and water, together with a basic catalyst, in the presence of a foam-stabilizing agent that is a polymeric material containing groups reactive with an organic isocyanate, e.g. an alkylated or acylated derivative of cellulose such as ethyl cellulose. The tetrahydrofuran, which may be prepared by the methods described in Specification 733,624, may be a linear hydroxy-ended polymer or it may be co-polymerized with less than 50% molar proportions of other cyclic ethers, e.g. ethylene oxide, epichlorhydrin &c., and/or with less than 5% molar proportions of poly functional agents, e.g. glycerol, substituted oxacyclobutanes &c. The polyisocyanate may be a diisocyanate, e.g. tolylene 2, 4 diisocyanate or mixtures of related diisocyanates, e.g. m- and pphenylene diisocyanates etc., and may be admixed with triisocyanates, e.g. 2, 4, 6 triisocyanato toluene &c., in proportions of less than 20% molar. Suitable catalysts are tertiary amines, e.g. NN1 dimethyl-benzylamine &c. Organo-polysiloxanes and surface active agent may also be added to the foam-forming mix to vary the uniformity and size of the pore structure. Emulsifying agents flame-proofing materials, plasticizers, colouring materials and fillers can also be included.ALSO:Cellular polymeric material are manufactured by interacting a hydroxy-ended polytetrahydrofuran, a polyisocyanate and water, together with a basic catalyst, in the presence of a foam-stabilizing agent that is a polymeric material containing groups reactive with an organic isocyanate, e.g. an alkylated or acylated derivative of cellulose such as ethyl cellulose. The tetrahydrofuran which may be prepared by the methods described in Specification 733,624 maybe a linear hydroxy-ended polymer or it may be co-polymerized with less than 50% molar proportions of other cyclic ethers, e.g. ethylene oxide, epichlorhydrin, &c., and/or with less than 5% molar proportions of polyfunctional agents e.g. glycerol, substituted oxacyclobutanes, &c. The polyisocyanate may be a diisocyanate e.g. tolylene 2,4 diisocyanate or mixtures of related diisocyanates e.g. m-and p-phenylene diisocyanates &c., and may be admixed with triisocyanates, e.g. 2, 4, 6 triisocyanatotoluene &c., in proportions of less than 20% molar. Suitable catalysts are tertiary amines, e.g. NN1 dimethylbenzylamine &c. Organopolysiloxanes and surface active agents may also be added to the foam forming mix to vary the uniformity and size of the pore structure. Emulsifying agents, flame-proofing materials, plasticizers, colouring materials and fillers can also be included.