GB822546A - Cellular elastomeric materials - Google Patents

Abstract

A method of producing cellular elastomeric materials comprises forming a liquid or plastic composition comprising a polymer containing isocyanate or isothiocyanate groups, a compound of molecular weight greater than 200 containing at least two groups capable of reacting with and cross-linking the polymer and an inert gas under pressure, foaming the composition by reducing the pressure thereon and subsequently setting the composition by furthering the condensation thereof before substantial breakdown of the foam occurs. As cross-linking agents there can be used organic poly-hydroxy compounds, diamines and aminoalcohols. Suitable polyhydroxy compounds are liquid hydroxy-polyesters, poly-(carboxy-/hydroxy-)-polyesters and hydroxy-polyethers. Preferably the hydroxy-polyesters, in addition to terminal or near-terminal hydroxy groups, contain one or more other intermediately-situated hydroxy or carboxy groups. Suitable esters can also be obtained by dehydration or blowing of vegetable oils, such as castor oil, which contain one or more hydroxy groups in the acid radical. The polycarbonates, such as can be obtained by phosgenation of glycols and other polyhydroxy compounds can also be used. The polymers containing isocyanate or isothiocyanate groups include reaction products of polyethers, polyesters or polyesteramides with a slight stoichiometrical excess of organic polyisocyanates or polyisothiocyanates. A liquefied gas and/or a volatile solvent may also be present in the starting materials. In examples: (1) a syrup obtained by reacting poly-ethylene glycol adipate and paraphenylene diisocyanate is stirred with a cross-linking agent comprising an adipic acid/polyethylene glycol/trimethylol propane reaction product while a mixture of triethylamine and an N-diethyl-ethanolamine/adipic acid reaction product is passed in through the stirrer. Concurrently carbon dioxide is fed in to give a working pressure of 200 lbs. sq. inch. The mixture then passes out to trays where it foams up and the foam is finally matured by heating; (2) a similar process employs an hydroxy-polycarbonate as the cross-linking agent. Specification 803,771 is referred to.ALSO:A method of producing cellular elastomeric materials comprises forming a liquid or plastic composition comprising a polymer containing isocyanate or isothiocyanate groups, a compound of molecular weight greater than 200 containing at least two groups capable or reacting with and cross-linking the polymer and an inert gas under pressure, foaming the composition by reducing the pressure thereon and subsequently setting the composition by furthering the condensation thereof, before substantial breakdown of the foam occurs. As cross-linking agents there can be used organic polyhydroxy compounds, diamines and amino-alcohols. Suitable polyhydroxy compounds are liquid hydroxypolyesters, poly (carboxy/hydroxy) polyesters and hydroxypolyethers. Suitable esters can also be obtained by dehydration or blowing of vegetable oils, such as castor oil, which contain one or more hydroxy groups in the acid radical. Polycarbonates such as can be obtained by phosgenation of glycols and other polyhydroxy compounds can also be used. The polymers containing isocyanate or isothiocyanate groups include reaction products of polyethers, polyesters or polyesteramides with excess polyisocyanate or polyisothiocyanate. A liquefied gas and/or a volatile solvent may also be present in the starting materials. In examples (1) a syrup obtained by reacting polyethylene glycol adipate and paraphenylene diisocyanate is stirred with a cross-lining agent comprising an adipic acid/polyethylene glycol/trimethylolpropane reaction product while a mixture of triethylamine and an N-diethylethanolamine/adipic acid reaction product is passed in through the stirrer. Concurrently carbon dioxide is fed in to give a working pressure of 200 lbs/sq. in. The mixture then passes out to trays where it foams up, and the foam is finally matured by heating; (2) a similar process employs a hydroxy-polycarbonate as the cross-linking agent. Specification 803,771 [Group IV(a)] is referred to.