Patent GB-882738-A (GB)
Title: Improvements in method of curing polyurethane elastomers and products resulting therefrom
IPC: C08G63/16
Filed: 1959-11-27
Abstract: Zeolites specified for use in forming clathrate compounds are naturally occurring and synthetic crystalline metal aluminium silicates.  These include "molecular sieve 13X" (a commercial product similar to fanjasite which has a composition Na2O:Al2O3:2,67SiO2: nH2O and has a free diameter in the channels of about 12 angstroms and "molecular sieve 4A" of composition Na2O:Al2O3:2SiO2:0,17NaAlO2: nH2O and which has a free diameter in channels of 4,2 angstroms. Clathrates are formed with water, anhydrous ammonia, amino alcohols, glycols and amines.  Specifications 791,618 and 858,689 are referred to.ALSO:A method of making a cured polyurethane compound comprises forming a clathrate between a curing agent and an inclusion compound which renders said curing agent substantially inert and thereafter mixing the clathrate with a compound selected from polyesters, polyethers, polyesteramides, polyether esters and admixtures thereof with an excess of an organic polyisocyanate at a temperature below the critical temperature of the clathrate to form a polyurethane intermediate which will have a substantially unlimited pot life at temperatures below the critical temperature of the clathrate but will commence to appreciably cure to form a polyurethane elastomer at temperatures above the critical temperature, and thereafter subjecting the polyurethane intermediate to curing conditions.  The clathrate may be added to the polyester, polyether, polyesteramide or polyether -ester (with subsequent addition of a polyisocyanate) or to a prepolymer. Particularly applicable curing agents are water, ammonia and amine-type curing agents of the following classes: (I) aromatic polyamines containing more than 1 and less than 5 primary amino groups per molecule, having a molecular weight less than 300; (II) aliphatic polyamines in which the sum of the numbers of primary and secondary groups is more than 1 and less than 5 and M.W. less than 300; (III) mono-amines of the formula RR1R11N wherein R is an aliphatic saturated hydrocarbon group of 1 to 8 carbon atoms, R1 and R11 are hydrogen or alkyl groups of 1-3 carbon atoms; (IV) heterocyclic monoamines of the formula <FORM:0882738/IV (a)/1> wherein R is an aliphatic saturated hydrocarbon group having 0 to 3 carbon atoms and R1, R11 and Y are alkyl groups p  having 1 to 4 carbon atoms.  The vapour pressure of compounds in each class should be greater than 10 mn. at 170 DEG C.  Amino alcohols and glycols are also referred to.  As inclusion compounds for the curing catalysts there can be used crystalline zeolites; naturally occurring materials such as foujasite, chabozite, sodium and potassium mordenite, levynite and bentonite; hydroquinone, urea, thiourea and desoxycholic acid adducts.  The clathrate can be added to a prepolymer or to the initial reactants from which it is prepared.  After shaping or forming the mixture, curing is effected by heating to a temperature at least 10 degrees above the critical temperature of the clathrate, generally at not less than 140 DEG C.  In Examples (1) a prepolymer from adipic acid and ethylene and proplylene glycols is mixed with a product similar to faujasite and having occluded ethylene diamine. The mixture is poured into a mould and cured by heating at 163 DEG C. under pressure; (4) a clathrate formed from ammonia and a molecular sieve of composition Na2O:A12O3:2SiO2:O,17NaA1O2: nH2O with channels of free diameter 4,2A is used; (5) the clathrate of (1) is used with a polytetramethylene glycol-diisocyanate adduct; (6) the clathrate of (4) is added to the polyester before addition of the diisocyanate; (7) to (10) clathrates of molecular sieves with 4,41-diamino-diphenylmethane, isobutylamine, trimethylamine and ethylenimine, respectively, are used.  Specification 858,689 is referred to.ALSO:Clathrates for use as a curing agent for polyurethanes (see Group IV(a)) are formed from crystalline hydroquinone, urea, thiourea and desoxycholic acid (as inclusion compounds) and water, glycols, aminoalcohols, ammonia, or amine-type curing agents.  The latter include aromatic amines containing 2 to 5 primary amino groups; aliphatic polyamines having 2 to 5 primary and/or secondary amino groups; monoamines; and heterocyclic compounds of the formula <FORM:0882738/IV (b)/1> wherein R is an aliphatic saturated hydrocarbon group having 0-3 carbon atoms and R1, R11 and Y are alkyl groups having 1 to 4 carbon atoms.  Specifications 791,618 and 858,689 are referred to.