| 摘要 |
<p>An isocyanate-terminated urethane prepolymer prepared by a urethane reaction between (A) a dihydroxypolyol and (B) an isocyanate compound, wherein the dihydroxypolyol is a mixture of (a) a polyether glycol or a polyether ester glycol containing an oxytetramethylene group and having a molecular weight of from 600 to 5,000 and (b) poly(tetramethylene ether/3-methyltetramethylene ether) glycol comprising a structural unit represented by formula (I): -CH2CH2CH2CH2O- (I> and from 5 to 40% by weight of a structural unit represented by formula (II) based on (b) poly(tetramethylene ether/3-methyltetramethylene ether) glycol: <CHEM> wherein R1 and R2 each represent a hydrogen atom or a methyl group, at least one of them being a methyl group, and having a molecular weight of from 500 to 5,000, with the proportion of (b) based on the total dihydroxypolyol (A) being from 1 to 50% by weight, at a B/A molar ratio of from 1.2 to 2.2. The urethane prepolymer exhibits liquid nature at low temperature of 10 DEG C or even less and therefore shows improved workability on mixing with a chain extender, a crosslinking agent, an elastomer modifying filler, and so forth.</p> |
