The difference between CTP plate and silver salt plate

The silver salt and PS plate composite direct plate mainly utilizes the high sensitivity and wide color sensitivity range of the silver salt emulsion layer to complete the laser direct scanning imaging of the plate material, and the printing process requirement is completed by using the excellent printing suitability of the PS plate. A clever combination of the use of mature silver salt photographic materials and PS plate technology to construct direct plates has caused a sensation in the early days of direct plate.

As with the diversity of platesetters, the diversity of direct plate systems is dazzling. Currently, there are silver salt plates, photopolymer plates, infrared thermal plates and inkjet plates. Four major categories.

Silver salt plate

Silver salt plates are mainly composed of silver salt and PS plate composite plates, up-diffusion plates and down-diffusion plates.

The silver salt and PS plate composite direct plate mainly utilizes the high sensitivity and wide color sensitivity range of the silver salt emulsion layer to complete the laser direct scanning imaging of the plate material, and the printing process requirement is completed by using the excellent printing suitability of the PS plate. A clever combination of the use of mature silver salt photographic materials and PS plate technology to construct direct plates has caused a sensation in the early days of direct plate.

The printability and print durability are identical to the traditional PS version. However, such a plate has a complicated structure and requires post-treatment such as multiple exposure and development (fixing), and the process is cumbersome. This is also the main reason why such a plate is difficult to achieve large-scale industrial application.

The upward diffusion type direct plate is composed of a plate base, a silver salt emulsion layer and a physical development core layer. After laser scanning imaging, diffusion development is performed.

The silver ions in the unexposed area are diffused upward, and are reduced to metallic silver by the surface physical development nucleus to become an oleophilic surface; the surface layer of the exposed region is still an emulsion layer and has good hydrophilicity. The base of such a plate may be a metallic material such as aluminum or a flexible polymeric base such as a polyester base, which in most cases is a flexible polymeric base.

The downward diffusion type silver salt plate is composed of an aluminum plate base having a good hydrophilic surface, a physical development core layer, and a silver salt emulsion layer.

After laser scanning imaging, diffusion development is performed. The silver ions in the exposed region diffuse downward, and are reduced to metallic silver by the underlying physical development nucleus to become the final oleophilic surface; then the emulsion layer is removed, and the hydrophilic substrate surface of the exposed region is exposed to become a hydrophilic layer. This plate has a very high sensitivity and sensitivity range, and its printing durability is also very high, suitable for high-end commercial printing.