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CTP PLATES

1、 At present, there are three main types of CTP plate: silver type CTP plate, photopolymer type and  thermal CTP plate
Let's take a look at the characteristics, advantages and disadvantages of these plates.
 
(1) Silver type CTP plate
 
Silver type CTP plate mainly includes silver type diffusion transfer plate and silver type and Positive PS Plate.
Silver type diffusion transfer plate is mainly composed of plate base, silver type emulsion layer and physical developing core layer. The diffusion transfer imaging technology is adopted, which is based on the silver type CTP plate exposed by laser scanning. In the developing solution containing silver halide solvent, Ag + and silver halide solvent complex and diffuse to the image receiving layer, reduce to metallic silver under the catalysis of physical developing core, and deposit on the surface of the body to form a silver image. At the end of development, the silver halide emulsion layer on the surface is removed by water washing, and the hydrophilic sand and image area in the non image area are exposed. In the fat sensing liquid, the long fatty chain organic molecules with sulfhydryl group are selectively adsorbed on the deposited silver surface to make the image area lipophilic.
Results the deposited silver image began to accept ink and repel water, but the non image part (silver free deposition) still repels ink, so as to achieve the purpose of computer direct plate making.

Silver type CTP plate
 
Silver type and PS plate composite plate are mainly composed of silver type emulsion layer with high sensitivity and PS plate with wide color sensing range. On the coarsened and anodized aluminum substrate, a pre sensitized photosensitive polymer layer, a bonding layer and a silver halide emulsion layer are successively coated. The imaging principle is that first, the silver type layer is exposed once by laser, and a picture and text silver image is formed on the resin layer, so that the photosensitive layer below can be protected from photosensitivity during the second exposure.
After one development, the emulsion layer of the non exposed part is dissolved, and then the second exposure is carried out, i.e. the whole panel is exposed with UV light. Because the image and text layer blocks the light, UV light only exposes the photodegradation sensitive resin layer of non image and text part. The resin layer after secondary development and secondary exposure is dissolved to expose the alumina plate base. Finally, the silver image layer can be treated with the solid solution.
 
Characteristics of Silver type CTP plate
 
1. Silver type CTP plate has a high sensitivity, which can reach 1-3 μ J / cm2. That is to say, using a laser with low output power, low energy and low intensity can also achieve high-speed plate output. Moreover, Silver type CTP plate is the most sensitive plate among CTP plates.
2. Silver type CTP plate is widely used in red laser, green laser and violet laser systems. Its washing method and post-treatment process are the same as the traditional method, and the CTP plate of different manufacturers is compatible with the formula of chemical solution.
3. Silver type CTP plate has the characteristics of high resolution, wide spectral response and good dot reproducibility. The number of screening lines can reach 300 lines / inch, dot coverage can reach 1% - 99%. The plate quality is excellent, and the printing resistance can reach more than 250000 prints. It is more suitable for large printing volume and high quality printing.
4. Because the silver type CTP plate uses expensive silver as raw material, the production cost is increased to a certain extent, and the silver type CTP plate cannot be operated in the open room, which brings some limitations to the plate preservation.

(2) Photopolymer CTP plate
 
The photopolymerized CTP plate is mainly composed of three parts, namely, the sanded aluminum plate base, the photosensitive layer and the protective layer.
 
Characteristics of photopolymer CTP plate
(1) The photosensitive layer of photopolymer 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 photopolymer 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!

Photopolymer CTP plate
 
(3) Thermal CTP plate
 
 Thermal 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, without any 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.


 
As we all know, the traditional CTP plate needs to go through development, fixation, cleaning, gluing, drying and other steps after imaging, and the process is relatively complex, while the CTP plate without treatment omits these processes, making the plate making process simple, thus shortening the plate making cycle.
Although the price of CTP plate without treatment is higher than that of conventional CTP plate, the cost of chemical consumption, post-treatment, personnel and supporting equipment are exempted or reduced, so the overall cost of plate making is reduced by 35%.
According to a survey of 63 printing factories of different sizes in the United States in the summer of 2003, printing enterprises spend $42500 to $17000 per year on developer, inventory, workshop, baking plate, equipment maintenance and waste treatment, compared with $5500 for cleaning unit and maintenance cost of CTP plate free, which is enough to make printing enterprises more easily accept CTP plate free

Processless CTP Plate

At present, Processless CTP Plate of treatment is divided into the following four types:
 
1. Process free CTP plate (pf CTP).
After plate imaging, no additional processing is required, such as prestek's applause hot melt CTP plate. In addition, some CTP plates made by convertible resin method also belong to this kind of plates
2. Chemical free plate (cfctp) . It is not suitable for chemicals and does not produce common waste liquid. It can be printed on the machine after being cleaned with clear water. Prestek anthem plate is an example
3. Simple process CTP plate (spCTP).
This plate needs some simple post-processing steps, such as glue.
It is a step ahead of the traditional chemical treatment plate, but there are still some chemicals in the treatment solution, so some waste liquid should be produced
4 on press developing  CTP plate (pdCTP).
When the imaged plate is installed on the printing machine for printing, the coating layer on the plate surface needs to be removed first.
In the face of strict environmental protection law, enterprises must pay attention to the environmental protection of the whole production process when printing production, and the CTP plate making process without treatment will not produce waste liquid, waste gas and waste which will damage the environment, so it is easy to be accepted by printing enterprises.