Positive-image thermosensitive light-sensitive composition and applications thereof

Abstract

The invention relates to a positive-image thermosensitive light-sensitive composition. A coating in an unexposed part is small in density and good in tolerance level, good in solvent resistance and good in scratch resistance. The composition is characterized by comprising phenolic resin, alkali-soluble solvent-resistant acrylic resin, sulfonamide-formaldehyde resin, an infrared absorption dye, a background dye, a dissolution inhibitor, and the like. The sulfonamide-formaldehyde resin is the critical component of the composition. A edition drying step is arranged in a production process in order to remove solvent in a coating formula and the temperature can reach 120-150 DEG C, and if ortho- or para- toluene sulfonamide-formaldehyde resin is added, after being baked, the ortho- or para- toluene sulfonamide-formaldehyde resin and other resin in a thermosensitive coating can be crosslinked. After the crosslinking is performed in the unexposed part, the alkali resistance and the strength of the coating are enhanced, so that the coating loss of the unexposed part during alkaline development is reduced. In the exposed part, the association of the infrared absorption dye and the phenolic resin is opened after heat absorption, and the infrared absorption dye is liable to dissolve in an alkaline developing solution, thus increasing the developing tolerance level of the thermosensitive coating.

Description

technical field [0001] The invention relates to a photosensitive composition, in particular to the photosensitive composition using sulfonamide formaldehyde resin and its application in positive thermosensitive CTP plates. Background technique [0002] With the development of computer image processing technology, people's attention has turned to photosensitive or thermal direct plate-making systems that directly image digital imaging information through laser beams or thermal heads without using silver salt coated films. The use of large-scale semiconductor lasers or YGA lasers has the following advantages over traditional photocuring plate-making methods: high-resolution images can be obtained through short-time exposure; time-saving effects; thermal direct plate-making plates used in the system can be operated under sunlight, reaching Labor saving effect. [0003] In recent years, the technology of adding a chemically amplified photoresist to a long-wave absorbing dye has...

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Problems solved by technology

[0005] The printing process is realized by applying the principle of water-ink balance. The support body with hydrophilic surface provides a hydrophilic surface, which is hydrophilic and ink-repelling. The photosensitive layer is exposed and developed to form an lipophilic layer, which is lipophilic and water-repelling. It has a fountain solution dampening process. In order to reduce the surface tension of the fountain solution, a certain amount of organic solvent is added to the fountain solution. At the same time, in the cleaning of the printing machine and other operations, there is an organic solvent that touches the printing plate, which affects the printing plate. The solvent-resistant type has certain requirements. The thermoplastic phenolic resin used in the general photosensitive layer has the following defects: poor wear resistance, low printing resistance when used as a lithographic printing plate, and poor solvent resistance, especially when using UV ink. even lower

In CN1891455A, CN1292508, and JP286964, the addition of acrylamide and acrylsulfonamide to the lithographic printing plate heat-sensitive layer formula is introduced to improve the solvent resistance of the lithographic printing plate. In CN1688657A (EP1554346B1), it is introduced in the N-imide groups are added to the layer formula to improve the solvent resistance of the lithographic printing plate. European patents EP1506858 and EP1738900 introduce the addition of N-vinylamide polymer to the lithographic printing plate heat-sensitive layer formula to improve the lithographic printing plate. In WO9963407 and WO2004035645, a kind of amide and imide structural units are introduced on the phenolic resin to improve the solvent resistance of the lithographic printing plate. However, although the solvent resistance of the printing plate has been improved, but New problems arise again. Adding the above-mentioned polymer causes the unexposed part of the printing plate precursor to have poor alkali resistance and soft hardness, which increases the coating loss of the precursor during development, and the precursor has low development latitude and scratch resistance. not ideal

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