Patent GB-802375-A (GB)
Title: Process for making plastic foams from polyurethane products
Inventor: ROUSSEL PHILIP ANDREW
IPC: C08G18/18
Filed: 1955-11-28
Abstract: A process of preparing a cellular plastic material from a water-foamable fluid polyurethane product containing unreacted isocyanate radicals and formed by the reaction between an arylene diisocyanate and at least one long-chain compound containing a plurality of hydroxyl groups, comprises mixing the polyurethane product with water and a catalyst mixture comprising 1 molar part of a water-soluble tertiary amine having a basicity such that its 25 per cent aqueous solution (25 parts by weight to 75 parts by weight of water) has a pH of at least 8.5 and from 0.25 to 3 molar parts of a salt of a tertiary amine having a basicity such that its 25 per cent aqueous solution has a pH of at least 8.5, said salt being formed from an acid at least as strong as acetic acid, the amount of water being from about 1 to 2 times the stoichiometric equivalent of the unreacted isocyanate radicals in the polyurethane product, and the amount of free tertiary amine being from 0.01 to 0.04 mols. for each equivalent of unreacted isocyanate radicals in the polyurethane product.  By the term "long-chain compound containing a plurality of hydroxyl groups" is meant an alkyd resin containing terminal hydroxyl groups or a fatty acid triglyceride derived from hydroxyl group-containing fatty acids and having a plurality of hydroxyl groups which triglyceride may, if desired, be employed in conjunction with a compound containing a plurality of hydroxyl groups and having a molecular weight below about 200, such as ethylene glycol.  The intermediate polyurethane employed may be a reaction product of an arylene diisocyanate with a fatty acid triglyceride of hydroxyl number at least 49, such as castor oil.  The intermediate product prepared in the process of Specification 790,527 is also suitable. Other suitable materials are hydroxypolyesters prepared, for example, from glycol, glycerol or trimethylolpropane and adipic, phthalic or succinic acids. Amines specified are diethyl or dimethyl ethanolamine, methylmorpholine, pyridine and trimethyl amine.  In forming the amine salts there can be used hydrochloric, nitric, sulphuric phosphoric or acetic, or other organic acids.  Specified dispersing agents which may be mixed with the added water are sodium carboxymethyl cellulose, lignin sulphonates, the lauric acid ester of triethanolamine, gelatine and the diethyl cyclohexylamine salts of alkyl sulphates containing from 12 to 16 carbon atoms.  As fillers there may be employed magnesium carbonate, powdered wood cellulose, bentonite, silicon dioxide, calcium silicate, carbon black, glass fibre, magnesium stearate and methylene distearamide.  In examples: (1) an unfoamed product containing 0.38 equivalents of NCO per 100 grams is prepared by reacting 2,4-tolylene diisocyanate, castor oil and polyethylene glycol.  It is foamed by mixing with an aqueous solution of diethylethanolamine partially neutralized with hydrochloric acid (the ratio of amine to amine hydrochloride is 0.5 : 1), and poured into a mould; (2) and (6) separate portions of the intermediate polyurethane of (1) are foamed with aqueous mixtures of various proportions of amine to amine salt and also (for comparison) with proportions outside those specified above, and with the amine alone; (3) foams are prepared similarly to Example (1), but using for the amine and amine salt dimethylethanolamine, N-methylmorpholine and pyridine and their hydrochlorides, respectively; (4) the proportion of water is varied and the effect on shrinkage is tabulated; (5) in place of the hydrochloride used in Example (1) there are used the nitrate, sulphate, phosphate, acetate and formate, respectively; (7) an intermediate polyurethane prepared by reacting castor oil with 2,4-tolylene diisocyanate is foamed by reacting with an aqueous mixture of diethylethanolamine and its hydrochloride and (for comparison) with aqueous diethylethanolamine alone; (8) a polyester-diisocyanate reaction product from an oil modified alkyd of hydroxyl number 100 and 2,4-tolylene diisocyanate is converted to foam by reaction with an aqueous mixture of diethylethanolamine and its hydrochloride.  Specification 719,715 is also referred to.