| 摘要 |
<p>Polyurethanes are prepd. by reacting a polyisocyanate with a mixt. of high mol. wt. polyol (I) and low mol. wt. polyol (II). (I) is a polyhydroxy polyesteramide obtd. by condensation of caprolactam with OH- and/or COOH gps. contg. cpds. normally used for prepg. polyesters, the amt. of caprolactam w.r.t. total reactants being >1%, pref. 2-30%. (II) is butanediol. (I) and (II) are compatible and their blend does not require an additive (e.g. Silica) to stabilise the blend during storage. The blend is also more fluid than a conventional polyhydroxy polyester. The polyesteramide enhances the flexibility of microcellular elastomers while preserving the mechanical properties. The polyurethanes obtd. are suitable for prodn. of hard or flexible opt. foamed mouldings e.g. shoe soles, printing rolls, automobile components, conveyor belts etc.</p> |
