Process for preparing non-yellowing integral-skinned polyurethane foam using a polyol having a functionality of 4 to 8

A process for preparing an integral-skinned polyurethane foam of improved heat and weathering resistance wherein a foamable composition for formation of polyurethane which comprises one or more polyols, a polyisocyanate, a cross-linking agent, a catalyst, and a blowing agent is reacted and expanded in a mold, characterized in that

• (a) said one or more polyols are polyether polyols having a terminal ethylene oxide adduct rate of at least 60%, an OH number of 20 to 100 and an average functionality of 4 to 8, or one or more polyester polyols having a functionality of 4 to 8;
• (b) said polyisocyanate is a non-aromatic polyisocyanate having an isocyanate index of 90 to 130;
• (c) said cross-linking agent is diethanolamine and ranges from 0.5 to 20 parts by weight based on 100 parts by weight of said one or more polyols;
• (d) said catalyst is an organometallic salt;
• and
• (e) said blowing agent is a halogenated hydrocarbon of a low boiling point.