反应详情

This example compares the relative effectiveness of the free-radical generation system of the invention with a control system. A solution of 2.5 g of 9:1 copolymer of methyl methacrylate and methacrylic acid in 5 g of 2-butanone was prepared, and to this solution was added 2.5 g of Epocryl® 12, 0.2 g of 2-o-chlorophenyl-4,5-diphenylimidazolyl dimer, 0.15 g of Michler's ketone, 0.01 g of Leuco Crystal Violet, 0.05 g of C.I. Solvent Red Dye #109, and enough 2-ethoxyethanol to give a total of 25 g of solution (Solution A). A second solution was prepared in which the 2-o-chlorophenyl-4,5-diphenylimidazolyl dimer of Solution A was replaced with a like amount of benzophenone (Solution B). The solutions were spin-coated onto anodized aluminum substrates (1000 rpm for 0.75 min.) to give coating weights of 37.9 mg/dm2 (Solution A) and 35.9 mg/dm2 (Solution B). The plates were exposed in air through the usual stepwedge process transparency to a 1000 watt tungsten-halogen lamp at a distance of 24.5 inches (62.4 cm), and the exposed plates were developed for 30 seconds with the development solution of Example 1. The results, summarized in Table II, show that the 2-o-chlorophenyl-4,5-diphenylimidazolyl dimer/Michler's ketone initiator system had a photospeed about ten times that of the benzophenone/Michler's ketone system.