| 摘要 |
<p>A polyurethane reaction mixture comprises a polyester polyol or polyether polyol of M.W. 500-8000, an organic polyisocyanate, a diamine or glycol cross-linking agent and about 0.5 to 8 parts by weight per 100 parts of the polyether or polyester of a secondary diamine of formula <FORM:1070759/C3/1> where y is an integer from 1-10, R is an alkyl radical of 8-30C, there being at least 1.1 mols. of polyisocyanate per mol. of polyether or polyester, the amount of cross-linking agent being substantially equivalent to the excess polyisocyanate. The secondary diamine may be N,N1-dihexadecyl propane 1:3-diamine, N,N1-diheptadecyl propane 1:3-diamine or N,N1-dioctadecyl propane 1:3-diamine. A polyurethane sheet may be formed by applying the reaction mixture to a surface to form a film of at least 0.001 ins. thick and curing the film.</p> |
