Compared with PS plate, there are many types of CTP offset printing plates. Among the many types, there are three main kinds: photopolymer plates, silverhalogen plates and thermal plates. Now let’s have a look of their pros and cons.
Silverhalogen Plates
The biggest advantage of silverhalogen printing plates is the sensitive photosensibility. So far, it is still the plate with the fastest photosensitive speed. Whether it is a thermal plate or photopolymer plate, it can’t be as fast as the silverhalogen plates.
However, its disadvantages are also obvious. Firstly, photosensitive materials have always been expensive. Secondly, this plate has high requirements for inks and its printing resistance is also not so good. More importantly, the development process of silverhalogen printing plates brings toxic waste liquid and causes pollution to the environment.
Thermal CTP Plates
Thermal CTP plate has very low sensitivity to natural light. The infrared laser is used for exposure, and it can be operated in bright room conditions. The lattice point of the thermal plates have good reproducibility, high resolution and sharp edge. It has excellent printability, and has a printing resistance of 1 million times after baking. Therefore, it dominates the commercial printing.
But it has high requirements for ambient temperature and humidity. In addition, its sensibility is not as good as the the others.
Photopolymer plates
It is generally composed of an aluminum plate base, a photosensitive layer, and a surface layer. Violet laser technology is very popular now. Violet laser printing plates are more active and require very low energy to expose and image. So it is widely used in newspaper industry.
This technology determines that the plates need to be stored in a dark room. Besides, its dot recovery is relatively poorer compared with thermal ctp plates.