Composition of flexible polyurethane foams below using reduced amounts of chlorofluorocarbone blowing agents and method for preparation

Flexible polyurethane foams prepared from formulations requiring reduced amounts of chlorofluoro-carbon blowing agents are disclosed. The foams can be prepared without undesirable loss of physical properties with formulations comprising an "A" component which is a blend of a polymethylene polydiphenyldiisocyanate and a methylene diphenyldiisocyanate prepolymer wherein the methylene diphenyldiisocyanate prepolymer is prepared from a prepolymer formulation containing an active hydrogen containing compound which has an equivalent weight of about 30 to about 600; a "B" component which includes an active hydrogen containing compound; and a carbon dioxide generating blowing agent. Also disclosed are polyisocyanate blends consisting of polymethylene polydiphenyldiisocyanate and methylene diphenyldiisocyanate prepolymers useful for preparing flexible polyurethane foams. Methods of preparing both the foams and the polyisocyanate blends are also disclosed. The foams of the present invention can be prepared to have improved tensile and tear values. Formulations of the present invention also display advantageously improved processing characteristics such as flowability.