Now there are four kinds of CTP plates on the market, which are heat sensitive, silver salt, photopolymerization and non treatment.
Thermosensitive CTP plate: it is now mainly hot melt type and heat crosslinking type.
Characteristics of thermal CTP plate
(1) The thermal CTP plate is exposed by infrared laser with low natural light sensitivity, so it can be operated in the open chamber.
(2) In order to generate image, the thermal sensitive plate must reach the initial thermal threshold, and the thermal energy higher than the initial threshold will not change the dot shape, which is the only technology that can control and predict the results. The quality is easy to control, the publishing quality is stable, and the plate after exposure can be extended to 6 months before developing, which will have no impact on the quality of the plate.
(3) The thermal plate has good dot reproducibility, high resolution and sharp and clear edge of dot. It is easy to achieve ink balance when printing, and has good printing adaptability. The printing resistance of the plate after baking can reach more than 1 million prints.
Silver salt type
Silver salt CTP plate mainly includes silver salt diffusion transfer plate and silver salt and PS plate composite plate.
Characteristics of photopolymerization CTP plate
(1) The photosensitive layer of photopolymerization CTP plate is very thin, and the image part and blank part are basically on the same plane, which belongs to the traditional offset type.
(2) The photopolymerization CTP plate can be made of purple laser diode (410nm), argon ion laser (488nm), fdyag laser (532nm), infrared laser diode (830nm) and other light sources. You can't operate in the open room!
Treatment free classification:
Hot ablation plate, polarity conversion plate and hot melting plate
The thermal ablation plate is generally double-layer coating, the bottom layer is ink-friendly layer, and the upper layer is water-friendly layer. During exposure, the laser energy will burn the water-friendly layer to expose the ink-friendly layer, forming pictures and texts; the unexposed part still remains hydrophilic, which is blank. The thermal ablation technology is not smooth in practical application, mainly because the dust and debris generated after ablation will affect the accuracy of the optical components of the plate making machine, Moreover, the blank part of the thermal ablation plate is hydrophilic coating, and its ink balance control ability and printing resistance are inferior to the traditional PS plate and CTP plate
The non treatment plate with polarity conversion technology is a single-layer coating, and the drug film layer is hydrophilic (or lipophilic). After exposure, the polarity of the drug film layer changes to lipophilic (or hydrophilic), and the exposed part is the graphic (or blank) part of the plate. Such plate can be directly printed on the machine without any treatment after exposure. However, due to its poor printing control and printing resistance, etc, There is still a long way to go before large-scale commercial application
There are many advantages of CTP plate without treatment. The production efficiency is improved without chemical development, the energy consumption is reduced during exposure, the overall plate making cost is reduced, and the plate making process cycle is shortened