GB1480972A - Process for manufacturing polyurethane foams having elasticity - Google Patents

Abstract

1480972 Polyurethane foams NAPHTACHIMIE 17 April 1975 [19 April 1974 21 March 1975] 15921/75 Heading C3R Flexible polyurethane foams are prepared by reacting in the presence of an expansion agent and a catalyst, at least one organic polyisocyanate, at least one hydroxyl and/or amine cross-linking agent and a polyetherpolyol component which consists of: (a) at least one polyether-polyol having an equivalent weight of from 1000-3000 and a mean theoretical functionality of 2-4 prepared by polyaddition of polypylene oxide and 0-30% wt. of ethylene oxide, based on the weight of the alkylene oxides, to at least one polyhydroxyl compound; and (b) from 0À1 to 5% by wt. based on polyol (a) of at least one auxiliary polyether polyol having an equivalent weight of from 1000-5000 and a mean theoretical functionality of 2-4 prepared by polyaddition of ethylene oxide and propylene oxide to at least one polyhydroxyl compound, 30-95% wt. of the attached alkylene oxides being ethylene oxide. The polyether polyols may be prepared by a random polyaddition of a mixture of ethylene and propylene oxides to the polyhydroxyl compound or by the successive polyaddition of propylene oxide and then ethylene oxide to the polyhydroxyl compound in the presence of an alkyline catalyst. Suitable polyhydroxyl compounds are water, ethylene and propylene glycols, polyethylene and polypropylene glycols, glycerol, trimethylolpropane, triethanolamine and pentaerythritol. Suitable cross-linking agents have an equivalent weight below 400, e.g. monoethylene glycol, diethylene glycol, triethanolamine, diethylenetriamine, methylene-bis-(ortho-chloraniline) and polyether polyols obtained by the polyaddition of alkylene oxides to water, polyols, amines or alkanolamines. The expansion agent may be water and/or a volatile organic compound such as monofluorotrichloromethane or methylene chloride. The polyisocyanates are preferably aromatic, such as polyphenylpolymethylene polyisocyanates, tolylene diisocyanates and 4,4- diphenylmethanediisocyanate, the latter two optionally being in crude form. Suitable catalysts are tertiary amines optionally in combination with a metallic catalyst, e.g. stannous octoate, dibutyltin-dilaurate or zinc octoate. A silicone emulsifier may be used. The foams are preferably prepared by the one-shot technique. Self-extinguishing foams can be obtained if the self extinguishing ratio "SE" obtained by dividing the number of OH groups derived from polyether polyols (a) and (b) and any polyhydroxyl cross-linker, by the sum of the number of water molecules plus the number of primary or secondary amine groups in any amine crosslinker, is at least 20 times the apparent specific gravity of the foam. The foams generally have a density of 10-50 g./dm.<SP>3</SP>. In the examples foams are prepared by the one-shot technique from reaction mixtures comprising (a) a polyether polyol prepared by condensing glycerol with propylene oxide and then with ethylene oxide, (b) a polyether polyol prepared by condensing water with a mixture of propylene and ethylene oxides; an 80/20 mixture of 2,4- and 2,6-tolylene diisocyanates, water and either (1) methylene bis(orthochloroaniline) and triethylene diamine; or (2) triethylenediamine, monoethylene glycol and a silicone stabilizer; or (3) diethylene triamine, a silicone stabilizer, methylene bis(orthochloroaniline), glycerine and monofluorotrichloromethane