GB885234A - Polyurethane compositions - Google Patents

Abstract

Odourless polyurethane compositions comprise the reaction product of a polyisocyanate, an active hydrogen-containing compound, and an amount, preferably 0,25 to 5,0 parts per 100 parts of the other two reactants, of an N,N1-bis (2-hydroxyalkyl) piperazine as catalyst. By including water among the reactants foamed products are obtained. The catalyst conforms to the structural formula <FORM:0885234/IV (a)/1> wherein R1 and R2, and R3, R4, R5 and R6 are hydrogen, alkyl, aryl or alkylaryl; R1 and R2 are preferably ethyl or propyl groups, and 2-methyl-and 2,5-dimethyl piperazine compounds are preferred. Specified reactive hydrogen-containing compounds include polyesters, polyesteramides, polyalcohols, and polyether alcohols. Suitable polyisocyanates are listed in the Specification and include ethylene-, propylene 1,2-, butylene 1,3-, cyclohexylane 1,2- 2,4- toluene-, triphenylmethane-, 3,31-dimethyl-, and 4,4-biphenylenediisocyanate. The polyurethane reaction may be effected by conventional technique, e.g. all the reactants may be simultaneously mixed together or the catalyst may be dissolved in water and the reactive hydrogen-containing organic compound added, followed by polyisocyanate; alternatively excess polyisocyanate may be reacted with reactive hydrogen-containing compound and aqueous piperazine catalyst solution added to the "prepolymer" formed in amount stoichiometrically equivalent to the "free" isocyanate content thereof. Reference has been directed by the Comptroller to Specifications 754,502 and 795,276.ALSO:Odourless foamed polyurethane products comprise the reaction product of water, a polyisocyanate, an active hydrogen-containing compound, and an amount, preferably 0,25 to 5,0 parts per 100 parts of the former two reactants, of an N-N1 bis (2-hydroxyalkyl) piperazine as catalyst which conforms to the structural formula:- <FORM:0885234/V/1> wherein R1 and R2, and R3, R4, R5 and R6 are hydrogen, alkyl, aryl, or alkylaryl; R1 and R2 are preferably ethyl or propyl groups; 2-methyl-and 25-dimethyl substituted piperazine compounds are preferred. Specified reactive hydrogen-containing compounds include polyesters, polyesteramides, polyalcohols, and polyether alcohols. Suitable polyisocyanates are listed in the Specification and include ethylenepropylene 1,2-; butylene 1,3-; cyclohexene 1,2-; 2,4-toluene-; triphenylmethane-, 3,31-dimethyl-; and 4,4 biphenylene-, diisocyanates. The polyurethane reaction may be effected by conventional techniques, e.g. all the reactants may be simultaneously mixed together or the catalyst may be dissolved in water and the reactive hydrogen-containing organic compound added, followed by polyisocyanate; alternatively excess polyisocyanate may be reacted with reactive hydrogen-containing compound and aqueous piperazine catalyst solution added to the "prepolymer" formed, in amount stocchiometrically equivalent to the "free" isocyanate content thereof. Reference has been directed by the Comptroller to Specifications 754,502 and 795,276.