First, the development trend of printing plate material
In the past, the typographic process used plain gravure plates and plated printing plates such as protein plates. These plates were based on zinc plate. In the 50's, people found that the surface of aluminum plates was treated with roughening (sanding) and had a good affinity. Waterborne, so the photosensitive liquid was pre-coated on a sanded aluminum base plate to make a PS plate. The use of this type of plate has become the dominant plate material for plain printing.
As the digitization technology of the platemaking process has developed rapidly in recent years, the CTP (Computer to Plate) technology, which uses different film manuscripts to produce the printing plate directly from computer platemaking data, has entered the practical stage. The exposure and development of the cTP plate are different from the traditional process. It is controlled by the printing plate positioning device and operated by laser beam scanning. This scanning method can be divided into planar shape, inner cylindrical shape, outer cylindrical shape, etc., and the mutual difference is relatively large. Its many characteristics are shown in Table I.
The exposure light source of the plate used in the CTP plate making process is a laser, and is classified into an optical scanning type and a thermal scanning type according to the wavelength thereof. The laser wavelength is in the visible range, the thermal scanning type is in the infrared range, and the optical scanning type is used. The plates are classified into photopolymerization types based on the light-sensitive material and image imaging methods, silver salt diffusion transfer type, silver salt polymer composite type, and electrophotographic type thermal scanning type plate materials are classified into thermal reaction type and laser type. Erosion type, phase change type, etc. (Table 2)
So far, various types of medium-thermal scanning models introduced by various plate-making companies have the advantages of bright-room operations, but high-power thermal laser devices are expensive and consume a lot of energy. In the future, various types of plates have been improved. The focus is on ease of use, low price, and better printability. The effect of the introduction of the CTP platemaking process into the printing industry and related issues are shown in Table 3. The resolution of these problems depends primarily on the full digitalization of printing. This helps the plate-making printing process to further improve efficiency and quality stability
(to be continued)
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