What is thermal CTP technology

The so-called CTP technology is the English abbreviation for computer to printing plate, printing press, CTProof, CTPaper/Print and CTcP. CTP of the current printing industry often say is from computer to plate (CTPlate), is the original diagram with computer, the digital processing, graphic unity and proofreading approval sample after, direct imaging on the plate, and then through developing post-treatment process and avoid reprocessing plate, etc. CTP technology can be divided into photosensitive CTP technology (visible light, purple laser, UV light) and thermal sensitive CTP technology.

I. classification of thermal sensitive CTP technology

Thermal sensitive CTP technology can be divided into the following categories according to plate materials:

(1) heat ablation type; (2) heat crosslinking plate (preheating type, negative type); (3) pyrolysis plate (no preheating treatment, positive pattern); (4) heat transfer plate; (5) thermally induced phase change plate.

Ii. Imaging principle of thermal sensitive CTP technology

Thermal sensitive CTP mainly USES thermal imaging technology and changes the state of materials after heat absorption by printing materials, so as to realize the change of material properties.

(1) heat ablation type

1. Plate composition

This plate is composed of silicone oil repellent layer, photothermal conversion layer (absorbent layer), oil-friendly layer and plate base (as shown in figure 1).

2. Imaging principle

The main function of the photothermal conversion layer is to absorb the light energy emitted by the infrared laser, and effectively convert the absorbed light energy into heat energy, so that the temperature of the plate increases to the level of vaporization temperature. See the light area of the solar-thermal conversion layer under the effect of thermal evaporation, the corresponding position of the silica gel is investing reservoir under the action of heat can be removed with vaporizing solar-thermal conversion layer, make the following pro reservoir bare accept ink plate graphic part; No vaporization occurred in the photothermal conversion layer in the light area, and the corresponding silicone oil repellent layer did not change, forming the blank part of the printing plate (see figure 2).

3. The version of the base

The substrate can be either metal (such as aluminum) or flexible polymer (such as polyester), with wide adaptability. This kind of plate material can be printed after laser imaging, so it is especially suitable for in-machine direct plate making system.

Although the plate also belong to without post-processing version material directly, but in the imaging process to produce the ablation vapor fog and debris, need to take necessary measures for sewage treatment, otherwise it would be for imaging optics and environmental pollution.

(2) heat crosslinking plate (preheating type, negative type)

1. Plate composition

The heat cross - linking plate is composed of heat - sensitive coating and hydrophilic substrate. Thermal sensitive coatings are generally composed of water-soluble film forming resins (phenolic resins), heat sensitive crosslinking agents and infrared dyes. The hydrophilic version can use the same aluminum version as the traditional PS version (see figure 3).

2. Imaging principle

The function of infrared dye is to effectively absorb the light energy of infrared laser, and convert the absorbed light energy into heat energy, so that the temperature of thermal sensitive coating can reach the reaction temperature of heat sensitive crosslinking agent. The effect of heat sensitive crosslinking agent is to react with the film forming resin under the action of temperature to form a space network structure, so that the heat sensitive coating loses water (alkali) solubility. Because of the space the effect of crosslinking, see the light area of thermosensitive coating in the role of thermal crosslinking reaction film forming resin by small molecules into large molecules, by linear molecules into the reticular molecule, has no alkali solubility, remain in layout after enhancement processing become oil-wet graphic part; The thermistor coating with no visible light area has no cross-linking reaction and is alkaline soluble. It is dissolved in the developing process and the hydrophilic substrate is exposed as a hydrophilic blank part (see figure 4).

3. Preheating treatment

Some materials in order to further improve the effect of thermal crosslinking, often after exposure to preheat the plate, thus further deepen thermal crosslinking effect (increased photosensitivity is also a kind of growth mechanism). This type of plate is called heat cross - linking plate that needs to be preheated. Thermal crosslinking of graphic plate area is composed of space crosslinking polymer resin, so this type of plate usually has a very high mechanical strength and resistance force, generally for hundreds of thousands of printing can be printed, very suitable for long printing market.