Thap DoMinh

High-speed nonsilver lithographic system for laser direct imaging

A high-speed nonsilver lithographic system has been demonstrated for direct laser imaging. The system is negative working and is based on a photoinsolubilization of a polymer coating by redox amplification. The essential components consist of a cobalt(III)amine (Coen), a redox transfer ligand (PAN), a light-sensitive quinone (Q), and a polysulfonamide binder (A6). On exposure, the quinone photogenerates a hydroquinone reducing agent. On heating, the hydroquinone reduces Coen to produce Co(II). PAN then complexes this Co(II) to form CO(II) PAN which, in turn, reduces more Coen. This resulting reaction produces Co(III)PAN and more Co(II) centers, which in the presence of excess PAN and Coen continues the cycle, giving photographically useful amplification. Polysulfonamide (A6) is an excellent medium with optimal acidity and thermomechanical properties to promote this chemistry. It provides toughness required for a dry-film photoresist, ink receptivity for lithographic plate, and aqueous development for both applications. Exposure to an Argon ion laser (4881514nm) at dose O.5-lmj/cm2 followed by heating (5 sec/120 C hot plate) produced high-density images that were insolubilized in an aqueous alkaline developer to give final nonswell images of excellent quality.

Photochromic aziridines. A novel photoisomerization and the geometry of colored intermediates in solution phase as compared to solid state

Cis-trans photoisomerization was observed in solution-phase photolysis of some photochromic aziridines, indicating a common planar intermddiate. However, in the solid state, each isomer produced a different color, and no photoisomerization occurred, indicating separate and noninterconvertible structures.

High Amplification Cobalt Imaging System

A novel high gain photothermographic imaging process is described. The essential components consist of a CoIII amine, a redox transfer lig- and L and a light-sensitive element capable of producing centers of CoII. On exposure, a reducing agent is produced, commonly via a quinone which photogenerates a hydroquinone. On heating, the hydroquinone reduces CoIII amine to produce CoII. The ligand then complexes this CoII to form CoII Ln, which, in turn reduces more CoIII amine. The resulting reaction produces a metallized dye, CoIIILn, amine and more CoII, which in the presence of excess L continues the cycle, giving photographically useful amplification. The system is capable of speed several thousand times that of an efficient one-quantum process.