GB797965A - Polyisocyanate compositions and foams produced therefrom - Google Patents

Abstract

The invention comprises a polyisocyanate composition comprising a polytetramethyleneether polyisocyanate polymer, said polymer having at least three free isocyanate groups attached thereto, with the proviso that there be not more than three free isocyanate groups per 1400 units of molecular weight of polymer, with at least 60 per cent of the total weight of the composition being a residue obtained by removing the terminal hydrogen atoms from a polytetramethylene-ether glycol having a molecular weight of from about 750 to 7500, said composition having a ratio of the number of free isocyanate groups to the number of isocyanate-bearing molecules greater than 2. Such compositions (described as "prepolymers") are converted into cellular products on reaction with water. The compositions can be prepared by reacting a mixture of di- and triisocyanates with the polytetramethylene-ether glycol. Alternatively, a polytetramethyleneether glycol is reacted with two mols. of a diisocyanate and the product then reacted with a further mol. of diisocyanate. Another method is to form a diester by the reaction of a polytetramethylene-ether glycol with a dibasic acid containing also a hydroxyl group in the molecule and reacting the product with 3 mols. of a diisocyanate. Similarly, a polytetramethylene-ether glycol ester of phosphoric acid may be reacted with 3 mols. of a diisocyanate. Another method is to react a polytetramethylene-ether glycol with 2 mols. of a diisocyanate, 3 mols. of the resulting diisocyanate product than being reacted with a trihydroxy compound such as glycerine. A further method is to react 3 mols. of a diisocyanate with a compound produced by reacting 1 mol. of a diisocyanate with 1 mol. of polytetramethylene-ether glycol and a trihydroxy compound. Another method is to react a triol, such as glycerin, with 3 mols. of a diisocyanate and the product may then be mixed with the reaction product of 1 mol. of a tetramethylene-ether glycol and 2 mols. of a diisocyanate. The proportion of isocyanate groups per molecule can be increased by reacting 2 mols. of the polymer with 1 mol. of a compound containing two reactive hydrogens such as a diamine or a glycol. Specified polyisocyanates are toluene-2,4, m-phenylene, 4-methoxy-m-phenylene and 1,6 - hexamethylene diisocyanates, methylene bis - (4 - phenylisocyanate), toluene - 2,4,6 - triisocyanate and diphenylether - 2,4,41 - triisocyanate. In the reaction of the prepolymers with water to give a foam there are usually added catalysts such as N-methyl morpholine, diethyl ethanolamine, triethylamine, pyridine, or aqueous potassium or sodium carbonate. Further diisocyanate and dimethyl-polysiloxane, colouring materials, pigments and emulsifying agents may also be added. In examples: (1, 1A to 1F) a mixture of toluene-2,4,6-triisocyanate and toluene-2,4-diisocyanate. The prepolymer obtained is then mixed with additional toluene-2,4-diisocyanate and dimethyl siloxane and then with water and N-methylmorpholine to give a foam. Tables specify the six different proportions of reactants and molecular weights of the polyether; (1g, 1h and 1i) in a generally similar reaction, benzene - 1,3,5 - triisocyanate, diphenylether-2,4,41 - triisocyanate and triphenylmethane-4,41411-triisocyanate, respectively, replace the toluene triisocyanate; (2a to 2c) a triisocyanate compound is prepared by reacting a polytetramethylene-ether glycol with toluene-2,4-diisocyanate and is then reacted with an aqueous mixture of N-methylmorpholine and its hydrochloride; (3) a triol (glycerol or trimethylolpropane) is reacted with 3 mols. of a polytetramethylene-ether urethane ditolyl isocyanate (from the polyether and 2 mols. of toluene-2,4-diisocyanate) and the triisocyanate obtained is foamed with water, a dimethyl-siloxane and N-methylmorpholine, in some cases with the addition also of toluene diisocyanate; (4) a triol is formed by reacting a polytetramethyleneether glycol (HO-G-OH), toluene-2,4-diisocyanate and a triol R(OH)3. The product (HO-G-OOCNH-T-NHCOO-R(OH)2) is converted to a prepolymer by mixing with tetramethylene-ether glycol and toluene-2,4-diisocyanate, the product being foamed by adding water, additional-2,4-diisocyanate catalyst and silicone; (5) mixtures of toluene-2,4-diisocyanate, polytetramethylene-ether glycol and a polyol (diglycerol, triethanolamine, ditrimethylolpropane adipate, and glycerol, respectively) are reacted to give prepolymers which are then foamed as in previous examples; (6) polyesters prepared by reacting polytetramethylene-ether glycol, polybasic acid (adipic) and polyol (glycerol or trimethylolpropane) or from tartaric acid alone, are converted to prepolymer by reaction with toluene diisocyanate, and foamed by adding aqueous potassium carbonate or diethyl-ethanolamine and its hydrochloride and a silicone; (7) (a) a prepolymer obtained by reacting toluene-diisocyanate with a polytetramethylene-ether glycol/toluene diisocyanate reaction product is foamed with water and diethylethanolamine and its hydrochloride, (b) a polyester prepared by reacting phosphorus oxychloride and polytetramethylene-ether glycol is reacted with toluene-2,4-diisocyanate and the prepolymer obtained is foamed with water and the amine/amine hydrochloride of Example (6), (c) polytetramethyleneether glycol and a tetrol (from the reaction of ethylene diamine and propylene oxide) are reacted with toluene diisocyanate and the prepolymer obtained is foamed by the addition of additional diisocyanate, water and N-methylmorpholine, (d) a prepolymer from polytetramethylene-ether glycol, toluene-2,4-diisocyanate and methylene-5,51-bis (toluene-2,4-diisocyanate) is foamed by the addition of toluene-2,4-diisocyanate, water and N-methylmorpholine; (8) a polyester from glycerine, adipic acid and polytetramethylene-ether glycol is reacted with toluene-2,4-diisocyanate and the resulting prepolymer is foamed by adding water and diethylcyclohexylamine.