Photosensitization mechanisms in photopolymer coating film containing photoinitiators sensitized by aminochalcone-type dye for computer-to-photopolymer plate
✍ Scribed by Toshiyuki Urano; Takumi Nagao; Akiomi Takada; Hiroki Itoh
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 163 KB
- Volume
- 10
- Category
- Article
- ISSN
- 1042-7147
No coin nor oath required. For personal study only.
✦ Synopsis
Photosensitization mechanisms in photopolymer coating film containing an aminochalcone-type dye sensitizer and a radical generating reagent, sensitizer dyes, (E)-3-(9-julolidinyl)-1-phenyl-2-propen-1-one (A), (E)-2-(9julolidinyl)-methylene-1-indanone (B), 9-benzoyl-2,3,6,7-tetrahydro-1H,5H-benzo[i,j]-furano-[3,2-g]quinolizine (C), 4-(dimethylamino) chalcone (D) and a radical-generating reagent, 2,4,6-tris (trichloromethyl)-1,3,5-triazine (TCT), were investigated by laser flash photolysis using a total reflection cell. Weak fluorescence and strong broad triplet absorption were detected. The fluorescence was statically quenched by TCT at quenching distances (R f ) of 15, 14, 20 and 14 A Ê for A, B, C and D as well as the triplet initial absorption, at quenching distances (R t ) of 16, 16, 16 and 14 for A, B, C and D, similar to the fluorescence quenching distances. The triplet decay time of the dyes was inefficiently quenched by TCT with the rate constants (k q ) of 1.9, 3.1, 0.7 and 1.0Â10 5 mol À1 /dm 3 /s for A, B, C and D. The sensitivity of photopolymers containing a sensitizer dye and a TCT was obtained at an excitation of 488 nm corresponding to the emission peaks of argon ion laser of 1.1, 0.2, 0.54 and 9.1 mJ cm 2 for A, B, C and D. The results indicated that the static sensitization process from the fluorescent singlet excited state of the dyes to the ground state of TCT was predominant, and the high sensitivity for A and B was caused by the high absorbance at 488 nm and that for C by the high fluorescent quenching distance.