| 摘要 |
<p>ÄProblemÜ To provide plastic lenses for spectacles, having a high refractive index and a high Abbe's number, and having good transparency, heat resistance, mechanical strength and impact resistance. ÄMeans for ResolutionÜ Provided are plastic lenses for spectacles, which are produced through polymerization of an epithio group-having compound (a), a polythiol compound (b) and a polyisocyanate compound (c) whereby the ratio of the polythiol compound (b) to the polyisocyanate compound (c) is at least 2.0 in case of a sulfur-free polyisocyanate compound (co) and is at least 1.2 in case of a sulfur-containing polyisocyanate compound (cs), calculated on the basis of mol-amounts of -SH and -NCO groups The invention also provides a process for preparing such lenses and a catalyst for use in said process.</p> |
