Improved photopolymerization initiator systems are comprised of a spectral sensitizer that sensitizes in the ultraviolet or visible regions of the spectrum and an N-aryl, O-aryl or S-aryl polycarboxylic acid co-initiator. The improved initiator systems are incorporated in photo-polymerizable compositions containing one or more addition-polymerizable ethylenically-unsaturated compounds to form compositions suitable for the preparation of radiation-sensitive layers in lithographic printing plates adapted to be imagewise-exposed with ultraviolet- or visible-light-emitting lasers such as argon-ion lasers and frequency doubled Nd:YAG lasers. Such plates are able to effectively meet the dual requirements of very high photospeed and very good shelf-life required in computer-to-plate systems.
                            改进的光聚合
引发剂体系由在光谱的紫外线或可见光区域敏化的光谱敏化剂和 N-芳基、O-芳基或 S-芳基聚
羧酸共
引发剂组成。改进后的
引发剂体系与含有一种或多种可加成聚合的
乙烯基不饱和化合物的光聚合组合物结合,形成的组合物适用于制备平版印刷板中的辐射敏感层,该板可使用紫外线或可见光发射激光器(如
氩离子激光器和倍频 Nd:YAG 激光器)进行图像曝光。这种印版能够有效地满足计算机直接制版系统对极高的光速和极好的保存期限的双重要求。