| 摘要 |
<p>A material composition comprising (a) a polyfunctional isocyanate, (b) a compound having a molecular weight of 600 to 3,500 and two functional groups undergoing a polyaddition reaction with an isocyanate group, (c) a compound having a molecular weight of 500 or less and two functional groups undergoing a polyaddition reaction with an isocyanate group, and (d) a compound having a molecular weight of 700 or less and three functional groups undergoing a polyaddition reaction with an isocyanate group. A molded polymer article is produced by heating a mixture of component (a) with a part of component (b) to prepare a urethane prepolymer, and adding the rest of component (b) and components (c) and (d) to the prepolymer, followed by heating to effect a polyaddition reaction between component (a) and components (b), (c) and (d). The obtained article can be applied to the parts where a high degree of shrinkage is required, is lowly toxic, and has large tear strength, tensile strength and elongation and a small permanent set.</p> |
