Patent GB-983586-A (GB)
Title: Polyurethanes and their manufacture
IPC: C08G18/40
Filed: 1961-04-25
Abstract: A method of preparing a polyurethane comprises reacting (1) an organic polyisocyanate with (2) at least one polyol selected from a polyether polyol, a mixture of a major amount of a polyether polyol and a minor amount of a polyester polyol and a polyether-ester polyol having a major amount of ether linkages as compared to ester linkages and containing at least two active hydroxyl radicals in amount sufficient to form a polyurethane in contact with (3) a minor amount by weight, based on the total weight of polyol present and sufficient to catalyze the reaction between the polyol and the polyisocyanate and to prevent dry heat degradation of the resulting polyurethane, of at least one aromatic tin catalyst selected from compounds of the formulae <FORM:0983586/C3/1> and [(R-[Ar]-CH2)2-Sn-B]z where R is hydrogen or an alkyl radical of from 1 to 5 carbon atoms; R1 is hydrogen, an alkyl radical of from 1 to 17 carbon atoms, or an aliphatic hydrocarbon radical having from 1 to 3 ethylenic linkages and from 2 to 17 carbon atoms; B is oxygen, sulphur, selenium, tellurium or <FORM:0983586/C3/2> where R11 is a carbon-to-carbon valence bond, an alkylene radical of from 1 to 16 carbon atoms, an aliphatic radical having from 1 to 3 ethylenic linkages and from 2 to 16 carbon atoms or a benzene, naphthalene, anthracene or biphenyl nucleus or a mono-alkyl ring-substituted derivative of such a nucleus in which the alkyl substituent has from 1 to 5 carbon atoms; D is oxygen, sulphur, selenium or tellurium; Ar is a phenyl, naphthyl, anthryl or biphenyl radical; v is a number from 1 to 2; w is a number from 1 to 18; x is a number from 1 to 3; y is a number from 3 to 1; z is a number from 1 to 3; and Sn is tin having a valence of four and has no unsatisfied valencies; and where the symbols R, R1, D and Ar (where they occur more than once in any compound) may have the same or different meanings within that compound.  The reaction may be conducted additionally with a minor amount by weight of water sufficient to provide foaming.  The reaction between the polyol and the polyisocyanate may be conducted additionally with the use of a tertiary amine catalyst. Foamed polyurethane may be manufactured by a two-stage process in which a prepolymer containing isocyanate groups is prepared from reactants (1) and (2) and is then mixed with tin compound (3) and a minor amount by weight of a blowing agent sufficient to provide foaming.  The polyether polyols may be polyalkylene ether glycols or branched chain polyether polyols obtained from alkylene oxides and, for example, sucrose, sorbitol, styrene-vinyl alcohol copolymers and others. Cross-linking materials, such as those containing 2 to 8 hydroxyl groups, may be added to the reaction mixture.  Polyesters to be used should have a molecular weight from 600 to 3000 or more.  They can be made with minor amounts of diamines or amino-alcohols, or glycerides of ricinoleic acid. From 0.5 to 12 equivalents of isocyanate and 0.05 to 5 equivalents of cross-linker hydroxyl, per equivalent of polyether hydroxy group can be used.  As blowing agents there can be used water (preferably with a tertiary amine catalyst), lithium aluminium hydride or liquid fluoro- or chlorofluoroalkanes. Other specified additives are silicones, vinyl, butyl or amyl triethoxy silanes, emulsifiers, carbon black, TiO2, SiO2, wood flour, metal flakes, natural and synthetic fibres, pigments, dyes, rubbers, resins.  The water can be added in the form of a rubber or resin latex.  Antidegradants such as alkyl phenols, N,N1-dialkyl phenylene diamines, alkyl and aryl phosphites and halogenated organic phosphites can be added.  Foamed products can be squeezed or wrung to break the cell walls. Non-cellular products can be used as films and coatings.  In an example foams are obtained by reacting together a triol (a propylene oxide adduct of glycerol), dibenzyl tin dilaurate, silicone block copolymer, water, N-methyl-morpholine, cyclic triethylene diamine, and tolylene-2,4- and 2,6-diisocyanates. Dibenzyl tin di-2-ethylhexoate is also a specified catalyst.