Abstract: Closed cell polyurethane foams, useful as thermal insulation for refrigerators and the like, are prepared by blending a polyisocyanate, a polyol and a suspension of at least one solid alkaline reagent, preferably sodium hydroxide, in an inert carrier liquid having a suitable viscosity. Preferred carrier liquids include polyepoxides and polyoxyalkylenediamines. The alkaline reagent reacts with and removes the carbon dioxide employed as a blowing agent, thus decreasing the thermal conductivity of the foam.

Abstract: Polyurethane foam of low thermal conductivity is prepared by employing carbon dioxide as a blowing agent, preferably in combination with a halogenated compound, typically a halocarbon or halohydrocarbon such as monofluorotrichloromethane or 1,1-dichloro-1-fluoroethane, and incorporating in the foam a carbon dioxide-reactive reagent. Sodium hydroxide and soda lime are illustrative carbon dioxide-reactive reagents. The carbon dioxide is preferably formed in situ by the reaction of water with the diisocyanate precursor of the polyurethane, and the carbon dioxide-reactivereagent is preferably introduced in admixture with a portion of the polyol precursor.

Abstract: Polyurethane foam of low thermal conductivity is prepared by employing carbon dioxide as a blowing agent, preferably in combination with a halogenated compound, typically a halocarbon or halohydrocarbon such as monofluorotrichloromethane or 1,1-dichloro-1-fluoroethane, and incorporating in the foam a carbon dioxide-reactive reagent. Sodium hydroxide and soda lime are illustrative carbon dioxide-reactive reagents. The carbon dioxide is preferably formed in situ by the reaction of water with the diisocyanate precursor of the polyurethane, and the carbon dioxide-reactivereagent is preferably introduced in admixture with a portion of the polyol precursor.