| 摘要 |
PROBLEM TO BE SOLVED: To produce a semihard polyurethane foam not accompanied by a gap forming problem by adding a specific amine to the polyurethane forming reaction mixture into a mold. SOLUTION: A plastic film or sheet is arranged in a mold and a reaction mixture containing at least one kind of a sterically hindered aromatic diamine, which has one or more 1-4C straight chain or branched chain alkyl substituent at an ortho position with respect to a primary amino group, and one or more 1-4C straight chain or branched chain alkyl group at an ortho position with respect to a secondary amino group, in an amt. of 0.5-5.0 pts.wt. per 100 pts.wt. of the reaction mixture is sprayed or injected into the mold in an amt. sufficient to fill the mold. Further, the amt. of the polyurethane forming reaction mixture containing org. polyisocyanate and the aromatic diamine is set so that the isocyanate index of the reaction mixture becomes 8-110 and the pts.wt. of the reaction mixture is made equal to 100. As polyether triol and diol with a relatively high mol.wt., one with an average mol.wt. of about 2,500-6,000 is proper. |
