Patent GB-968384-A (GB)
Title: Improvements in the manufacture of polyurethane foams.
IPC: C08G18/24
Filed: 1960-10-12
Abstract: 968,384. Foamed polyurethanes. GENERAL TIRE & RUBBER CO. Oct. 12, 1960 [Oct. 13, 1959], No. 34997/60. Headings C3C and C3R. A method of making a foamed polyetherurethane comprises reacting (1) at least one polyisocyanate with (2) at least one polyether polyol containing at least two active hydroxyl radicals in amounts sufficient to form a polyurethane in admixture with (3) a minor amount by weight of a foaming agent sufficient to foam the reaction mass of the polyol and the polyisocyanate and in contact with (4) a minor amount by weight based on the total weight of polyol present and sufficient to stabilize the foaming reaction of the polyol and the polyisocyanate and to obtain cells of substantially uniform size in the resulting polyetherurethane of at least one organic silane having the formula: where R 1 , R 2 , R 3  and R 4  each represent an alkyl radical of from 1 to 6 carbon atoms or an alkenyl radical of from 2 to 6 carbon atoms. In a second method a prepolymer obtained by reacting the polyisocyanate and polyether polyol in amounts sufficient to give a polyetherurethane having about 1 to 25% available reactive isocyanate groups is reacted with the foaming agent and a minor amount of the organic silane defined above. The polyether poylol may consist wholly or partly of a polyesterether polyol containing a major amount of ether linkages as compared to ester linkages. A minor amount of a polyester polyol may also be present. In examples of the silanes the alkenyl radicals are variously vinyl, allyl, hexenyl and butenyl. Usually 0À05 to 3%, based on the weight of polyol is used. As an additional modifier, especially, where the polyol has a large number of secondary hydroxyl groups, a diol of M.W. up to 2,000 having from 2 to 8 carbon atoms between oxygen atoms and being capable of dissolving water in an amount of at least 3% by weight. in an amount of from 0À1 to 3À0% based on the weight of the polyether polyol, may be added to the mixture. Glycols, and polyether glycols may be used for this purpose. The polyether polyols used as starting materials may be linear or may be branched compounds obtained by reacting glycols, alkylene oxides or oxetanes with sucrose, sorbitol, styrene-vinyl alcohol copolymers, hexanetriol, pentaerythritol, glycerol, phloroglucinol or trimethylolphenol, benzene or propane. Cross-linking polyols may also be present in the reaction mixture. As blowing agents water, fluoro- or chlorofluoroalkanes and liquefied hydrocarbon gases such as methane or ethane are suitable. Amine catalysts specified are triethylamine, trihexylamine, 4-N-amyl pyridine, N-methylmorpholine, 4-pyridine propanol, 2-ethanolpyridine, di(ethylene amino ethanol) adipate, dibutyl aminoethanol and N,N <SP>1</SP>-diethyl- 2-methyl piperazine. Aromatic tin catalysts (which also prevent heat degradation) can be used. These have 1 to 3 Ar-CH 2 - groups (where R is phenyl, naphthyl, anthryl or biphenyl) attached to tin. Remaining groups attached to the tin through O, S, Se or Te, are ester containing groups or O, S, Se or Te alone. Emulsifiers TiO 2 , SiO 2 , carbon black, wood flour, wool, cellulose, nylon and glass fibres, colours, dyes, deodorants, rubbers and resins can also be added. Suitable antioxidants are alkylphenols, N,N <SP>1</SP>-dialkylphenylene diamines, alkyl and aryl phosphites. The products can be heated and aged, or squeezed and wrung to break the cell walls. In typical example (I) a prepolymer from 2,4- and 2,6-tolylene diisocyanates and polypropylene glycol M.W. is mixed with amyl triethoxy silane, N-methylmorpholine, triethylamine and water to give a foamed product. This is crushed between rollers to give a 100% open cell structure; (8) a mixture of a propylene oxide adduct of glycerol containing 90-95 % secondary OH groups, trinonyl aryl phosphite, amyl triethoxy silane, tolylene diisocyanates, ethylene glycol and water reacts to give a foam of uniform cell structure. In examples given for comparison, unsatisfactory results follow, when the procedure of example (I) is modified (9) by omitting the silicon compound, (10) by using C 2 H 5 OCO(CH 2 ) 3  Si (OC 2 H 5 ) 3  or H 2 N(CH 2 ) 3 Si(OC 2 H 5 ) 3 , (11) by using heptyl triheptoxy silane, heptyl triethoxy silane or dibutyl diethoxy silane.