Two-colored molded product of polyurethanes made by RIM and process for manufacturing the same

A two-colored molded product of polyurethanes made by reactive injection molding and comprising:

• a surface portion formed by injecting an amount of a non-yellowing surface-forming polyurethane material containing a polyether polyol, a hexamethylene diisocyanate trimer, a coloring agent and a mixed catalyst into a closed mold cavity having a pressure below atmospheric pressure, the amount of surface-forming polyurethane injected being relatively small compared to the gross volume of said mold cavity, said mixed catalyst being a mixture of a first catalyst having the chemical formula ##STR3## and a second catalyst represented by the chemical formula ##STR4## where M stands for an alkali metal or an alkaline earth metal, and R stands for:
• hydrogen, an alkyl group having 1 to 20 carbon atoms, an alkenyl or alkynyl group having 2 to 20 carbon atoms, these groups being straight or branched and optionally may be substituted by one carboxyl group or one or more halogens,
• a cycloalkyl group having 3 to 6 carbon atoms, this group being unsubstituted or substituted by one carboxyl group, one or more alkyl groups having 1 to 6 carbon atoms or alkenyl or alkynyl groups having 2 to 6 carbon atoms, these groups being straight or branched, or
• an aryl group, this group being unsubstituted or substituted by one or more halogens, one or more alkyl groups having 1 to 8 carbon atoms or alkenyl or alkynyl groups having 2 to 8 carbon atoms, any of these groups being straight or branched, or by one aryl group or one carboxyl group;
• and
• an inner portion formed by injecting an inner-portion-forming polyurethane material into said closed mold cavity.