Patent GB-897710-A (GB)
Title: Low density, resilient polyurethane foams
IPC: C08G18/22
Filed: 1960-04-21
Abstract: A method for the production of a low density polyurethane foam comprises reacting an active hydrogen terminated polymer or a mixture of active hydrogen terminated polymer and non-polymeric active hydrogen containing compound with from 2 to 3 equivalents of a diisocyanate or mixture of diisocyanates per equivalent of active hydrogen present in the active hydrogen compounds present in the reaction mixture, at a temperature of from 25 DEG  to 130 DEG C. in an inert atmosphere, the diisocyanate or more than 20% of the mixture of diisocyanates being 2,6-tolylene diisocyanate, m- or p-phenylene diisocyanate or p,p1-diisocyanatodiphenylmethane and then mixing with the reaction product at normal room temperature and in an inert atmosphere sufficient of a diisocyanate or mixture of diisocyanates, the diisocyanate or more than 80% of the mixture of diisocyanates being 2,4-tolylene diisocyanate or 2,4-cumene diisocyanate, to impart a free -NCO content of from 10 to 17% by weight based on the weight of the mixture and adding to the mixture water and an alkaline catalyst, the catalyst being a tertiary amine, dibutyl tin dilaurate or potassium ricinoleate. Preferred active hydrogen-containing polymers are polyethers and polyesters having molecular weights from about 500 to about 10,000.  The polyethers can be condensation products of alkylene oxides with diols, triols, sucrose or sorbitol and may be mixed with small amounts of polyols and polyamines such as glycerol or tetrahydroxy ethylene diamine.  Representative acids and glycols from which the polyesters can be prepared are listed. Tertiary amine catalysts mentioned are triethylamine, N-methyl-morpholine, N,N,N1,N1-tetramethyl butane diamine, triethylene diamine, ethylene oxide-treated laurylamine, 2-dimethylamino-2-methyl propanol-1, and N,N1-dihydroxy propyl-2-methyl-piperazine.  Silicone oils may be added as foam stabilizers.  Examples describe the preparation of prepolymers and foams, by the above general method, from (1) a glycerolpropylene oxide reaction product, a mixture of 32,9% 2,6- and 67,1% 2,4-tolylene diisocyanates, a mixture of 97% 2,4- and 3% 2,6-tolylene diisocyanates, water, N-methyl morpholine and triethylamine.  The foam was heated at 70 DEG C., squeezed to break closed cells, and then heated at 120 DEG C.; (2) a pre-prepolymer obtained by reacting excess polypropylene oxide diol with mixed 35% 2;6- and 65% 2,4-tolylene diisocyanates adding N,N,N1,N1-tetraisopropanol and benzoyl chloride to the product, and reacting the mixture with a further amount of the mixed diisocyanates.  The product was converted to prepolymer by reaction with 97% pure 2,4-tolylene diisocyanate and then foamed. Prepolymers were also made from (5) a preprepolymer from the reactants specified in (1), ethyl cyanoacetate and a mixture of 96% 2,6-and 4% 2,4-tolylene diisocyanates; (6) a pre-prepolymer from polypropylene oxide triol, ethyl cyanoacetate and m-phenylene diisocyanate; (7) polytetramethylene oxide diol and the diisocyanates used in (1).  In (7) the conversion to foam was effected by reaction with silicone oil and a catalyst mixture of water, N-methyl morpholine, N,N,N1,N1-tetramethyl-1,4-butane diamine and an ethylene oxide treated lauryl amine.  Specification 825,896 is referred to.ALSO:A method for the production of a low density polyurethane foam comprises reacting an active hydrogen terminated polymer or a mixture of active hydrogen terminated polymer and non-polymeric active hydrogen containing compound with from 2 to 3 equivalents of a diisocyanate or mixture of diisocyanates per equivalent of active hydrogen present in the active hydrogen compounds present in the reaction mixture, at a temperature of from 25 DEG  to 130 DEG C. in an inert atmosphere, the diisocyanate or more than 20% of the mixture of diisocyanates being 2, 6-tolylene diisocyanate, m-or p-phenylene diisocyanate or p, p1-diisocyanateo-diphenylmethane and then mixing with the reaction product at normal room temperature and in an inert atmosphere sufficient of a diisocyanate or mixture of diisocyanates, the diisocyanate or more than 80% of the mixture of diisocyanates being 2, 4-tolylene diisocyanate or 2, 4-cumene diisocyanate, to impart a free- NCO content of from 10 to 17% by weight based on the weight of the mixture and adding to the mixture water and an alkaline catalyst, the catalyst being a tertiary amine, dibutyl tin dilaurate or potassium ricinoleate. Preferred active hydrogen-containing polymers are polyethers and polyesters having molecular weights from about 500 to about 10,000.  The polyethers can be condensation products of alkylene oxides with diols, triols, sucrose or sorbitol and may be mixed with small amounts of polyols and polyamines such as glycerol or tetrahydroxy ethylene diamine.  Representative acids and glycols from which the polyesters can be prepared are listed. Tertiary-amine catalysts mentioned are triethylamine, N-methyl-morpholine, N, N, N,1 N1-tetramethyl butane diamine, triethylene diamine, ethylene oxide-treated laurylamine, 2-dimethylamino-2-methyl propanol-1, and N, N1 - dihydroxy propyl - 2 - methyl - piperazine.  Silicone oils may be added as foam stabilizers.  Examples describe the preparation of prepolymers and foams, by the above general method, from (1) a glycerol-propylene oxide reaction product, a mixture of 32,9%2,6-and 67,1%2,4-tolylene diisocyanates, a mixture of 97% 2, 4- and 3% 2, 6 tolylene diisocyanates, water, N-methyl morpholine and triethylamine.  The foam was heated at 70 DEG C. squeezed to break closed cells, and then heated at 120 DEG C.; (2) a pre-prepolymer obtained by reacting excess polypropylene oxide diol with mixed 35% 2:6- and 65% 2, 4-tolylene diisocyanates adding N, N, N1, N1,-tetraisopropanol and benzoyl chloride to the product, and reacting the mixture with a further amount of the mixed diisocyanates.  The product was converted to prepolymer by reaction with 9% pure 2, 4-tolylene diisocyanate and then foamed.  Prepolymers were also made from (5) a prepolymer from the reactants specified in (I), ethyl cyanoacetate and a mixture of 96% 2, 6- and 4% 2, 4-tolylene diisocyanates; (6) a pre-prepolymer from polypropylene oxide triol, ethyl cyanoacetate and m-phenylene diisocyanate; (7) polytetramethylene oxide diol and the diisocyanates used in (1).  In (7) the conversion to foam was effected by reaction with silicone oil and a catalyst mixture of water, N-methyl morpholine, N, N, N1, N1-tetramethyl-1, 4-butane diamine and an ethylene oxide treated lauryl amine.  Specification 825,896 is referred to.