Study On A Heat-Sensitive CTP Imaging Composition And Its Performance

Computer-to-Plate (CTP) technology has been becoming popular in the printing industry in recent years because it can improve the speed of plate-making and the efficiency of printing. People have done a lot of work in this area.In this study, esterified phenolic resin containing carboxylic groups were synthesized through the esterification reaction of anhydride and phenolic resin. Positive-working heat-sensitive CTP imaging compositions consisting of the esterified resin, near infrared absorbing dye, crystal violet and cross-linking agent were prepared, which might be heat sensitive lithographic printing plate precursors. Investigations on these systems were carried out. Two kinds of phenolic resins are used in the esterification reaction. A series of esterified resins having varied esterification rates were used to construct the heat-sensitive compositions. The esterification rate of the resins was optimized through the evaluation of imaging performance of the corresponding heat-sensitive compositions. The imaging performance of the heat-sensitive resin layers was determined by measuring the dissolution behaviors in the alkaline developing solution, and the formula of the heat-sensitive compositions were optimized. In addition, the effect of dissolution inhibitor (oxidized tertiary amine), cross-linking agents as well as surfactant-like additives were on alkaline solubility of the heat-sensitive resin films before and after laser exposure were also studied. The dissolution inhibitor modified resin had relatively high alkali resistance, which exhibited lower sensitivity. Finally, a double-layer heat-sensitive film with the modified phenolic resin as the bottom layer and a pyrrolidone derivative as the top layer was prepared and investigated.