Double-Amplified Photoinitiator Systems for Computer to Plates.

Photoinitiation processes for photopolymer coating layers have been investigated with respect to quenching rates by a laser flash photolysis using total reflection cell, as well as to decomposition-quantum yield of sensitizer dyes and radical-generating reagents by a gel permeative chromatographic analysis (GPC); the sensitizer dye, 2-[p-(diethylamino)styryl]naphtho[1,2-d]-thiazole (DNT), and the radical-generating reagent, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,1'bi-1H-imidazole (BI). Strong fluorescence and no transient absortion were observed at excitation of 355 nm laser pulse, and the fluorescence was statically quenched with a quenching distance, R=11 u. The high-quantum yield of decomposition (() were obtained as ( (DNT)=2.5 and ( (BI)=9.3 for DNT and BI in the presence of acrylate monomers, trimethrolpropanetriacrylate (TMPTA), at 488 nm exposure of 3 mJcm-2 required to form photo-hardened image, though no decomposition of DNT and BI were detected in the absence of TMPTA. The results imply that the photoinitiator system accelerated photo-polymerization of the acrylate monmers not only by the efficient-static-dye sensitization but also by the chain decomposition of DNT and BI.