Abstract: Closed cell, rigid polymer foams are prepared by (a) continuously conveying a carrier along a production line, (b) supplying on the carrier a foam-forming mixture comprising a polyisocyanate, a catalyst, a hydrogen-containing blowing agent or a mixture of the hydrogen-containing blowing agent and at least one co-blowing agent, and an isocyanate-reactive component comprising (i) a high acid polyester polyol having an acid number greater than 1, or (ii) a mixture of the high acid polyester polyol and at least one other isocyanate-reactive compound, (c) passing the carrier and mixture between two constricting members forming therebetween a metering gap, and (d) allowing the mixture after passing through the gap to freely expand to form a plastic foam, wherein the acid number and amount of the high acid polyester polyol in the mixture are sufficiently high to result in a superior resistance to cold temperature shrinkage.

Abstract: Closed cell, rigid polymer foams are prepared by (a) continuously conveying a carrier along a production line, (b) supplying on the carrier a foam-forming mixture comprising a polyisocyanate, a catalyst, a hydrogen-containing blowing agent or a mixture of the hydrogen-containing blowing agent and at least one co-blowing agent, and an isocyanate-reactive component comprising (i) a high acid polyester polyol having an acid number greater than 1, or (ii) a mixture of the high acid polyester polyol and at least one other isocyanate-reactive compound, (c) passing the carrier and mixture between two constricting members forming therebetween a metering gap, and (d) allowing the mixture after passing through the gap to freely expand to form a plastic foam, wherein the acid number and amount of the high acid polyester polyol in the mixture are sufficiently high to result in a superior resistance to cold temperature shrinkage.