| 摘要 |
PROBLEM TO BE SOLVED: To provide a polyurethane prepolymer composition which is lowly viscous and therefore excellent in workability and to provide a cast polyurethane elastomer excellent in wear resistance and mechanical properties and free from voids. SOLUTION: Tolylene diisocyanate is reacted with a polytetramethylene ether glycol having a number-average molecular weight of 500-4,000. In the latter stage of or after the reaction, 1-20wt.%, based on tolylene diisocyanate, diphenylmethane diisocyanate is added to the reaction mixture to obtain an NCO-terminated urethane prepolymer mixture (pack A). This composition comprises pack A and a curing agent (pack B). |
