What is thermal sensitive CTP technology
2023-06-26
The so-called CTP technology refers to the abbreviation of computer to CTPlate, CTPress, CTProof, CTPaper/Print, and CTcP. The CTP commonly referred to in the current printing industry is from computer to printing plate (CTPlate), which uses a computer to digitize, integrate, and proofread the original image and text on the printing plate, directly imaging them, and then making a printing plate through post-processing processes such as development or no post-processing. CTP technology can be divided into photosensitive CTP technology (visible light, purple laser, UV light) and thermosensitive CTP technology. Below, we will focus on thermosensitive CTP technology.
1、 Classification of thermal sensitive CTP technology
Thermal CTP technology can be divided into the following categories according to the plate material:
(1) Thermal ablation type; (2) Thermal cross-linked plate (preheating type, negative pattern type); (3) Thermal decomposition type plate material (no preheating treatment, positive pattern type); (4) Heat transfer plate material; (5) Thermal induced phase change plate material.
2、 Imaging principle of thermal sensitive CTP technology
Thermosensitive CTP mainly utilizes thermal imaging technology to achieve changes in material properties by relying on changes in the state of the material after the printing plate material absorbs heat.
（1） Thermal ablation type
1. Plate composition
This type of plate is composed of a silicone exclusion layer, a photothermal conversion layer (absorption layer), a hydrophilic layer, and a substrate (as shown in Figure 1).
2. Imaging Principles
The main function of the photothermal conversion layer is to absorb the light energy emitted by infrared lasers and effectively convert the absorbed light energy into thermal energy, causing the temperature of the layout to rise to the level of vaporization temperature. The photothermal conversion layer in the visible area vaporizes under the action of thermal energy, and the corresponding silicone exclusion layer in the corresponding position is removed with the vaporization of the photothermal conversion layer under the action of heat, exposing the hydrophilic oil layer below to become the part of the printing plate that receives the ink; The photothermal conversion layer in the non visible area did not undergo vaporization, and the corresponding silicone exclusion layer did not change, forming the blank part of the printing plate (as shown in Figure 2).
3. Base
The substrate of this type of plate can be either a metal substrate (such as aluminum substrate) or a flexible polymer substrate (such as polyester substrate), which has a wide adaptability. This type of plate material is particularly suitable for in machine direct plate making systems because it can be printed after laser imaging.
Although this type of plate is also a direct plate that does not require post-processing, necessary measures need to be taken to dispose of it during the imaging process due to the generation of ablation vapor and debris, otherwise it will cause pollution to the imaging optics and the environment.
（2） Thermal cross-linked plate (preheating type, negative pattern type)
1. Plate composition
The thermal cross-linked plate is composed of a thermosensitive coating and a hydrophilic substrate. Thermal sensitive coatings are generally composed of (alkaline) water-soluble film-forming resins (phenolic resins), thermal crosslinking agents, and infrared dyes; The hydrophilic version can use the same aluminum version as the traditional PS version (as shown in Figure 3).
2. Imaging Principles
The Work of Infrared Dyes
View More
CTP plate material and its production method
2023-06-26
Computer To Plate (CTP) is one of the major trends in the development of printing technology in the first decade of the 21st century. It refers to the process of directly outputting digital pages onto printing plates through computers. CTP Computer to plate is composed of three parts: accurate and complex optical system, circuit system and mechanical system. The three parts are relatively independent, strictly coordinated and unified. This technology not only eliminates the need for traditional plate making processes such as laser phototypesetting and manual assembly and printing of soft films, but also saves equipment and materials required for intermediate processes. It avoids the drawbacks of dot loss, deformation, and expansion, reduces color and layer loss, and shortens the ink color adjustment and registration adjustment time and ink balance time during the printing process, greatly improving product quality and work efficiency. Since Autoligic developed the first computer direct plate making equipment in 1989, major equipment companies and printing manufacturers around the world have closely cooperated to accelerate the development pace of this technology research and gradually reached a mature and industrialized application level. Heidelberg, a world-famous printing equipment provider, and Pressek jointly developed the computer to plate on press technology and launched GTO-DI in 1991, becoming the first equipment in the world to make plates on a printing machine. At the DRUPA95 printing exhibition, the display of CTP system and direct plate making materials became the hottest technological highlights, indicating that the research on computer direct plate making technology has matured and entered the market.
CTP plate, also known as Computer To Plate, is a digital plate that can be directly made by a computer. Compared with the plate making process CTF of traditional PS plate, CTP plate has the advantage of short process flow, which can greatly improve the printing quality and shorten the production cycle, thus saving Labor burden. CTP plates can be divided into thermal sensitive, photosensitive, and silver salt based on their photosensitive principle.
The hot-rolled plate base mainly produced using the hot-rolled process. CTP plates produced using hot-rolled plates have inherent advantages over cast rolled plates due to their sufficient guarantee of tissue uniformity, as well as better control of surface quality and dimensional tolerances. In contrast, CTP plates produced using cast rolled plate substrates are prone to internal microstructure and surface defects due to production process conditions. During the production process of CTP plates (such as electrolysis, oxidation, coating, etc.), defects may occur, resulting in unstable quality. However, producing CTP plates based on cast rolled plates can reduce production costs, improve product cost-effectiveness, and enhance product market competitiveness.
At present, CTP plates are still produced using hot-rolled plates, and the technology for producing CTP plates using cast rolled plates is not yet mature. If CTP plates can be produced using cast rolled plates, it can fill the domestic and even international gap. How to use casting and rolling plate base and improve the electrolysis, oxidation, and coating processes to produce high-quality CTP plates has become a challenge for technology professionals
View More
CTP performance requirements for Digital printing plate
2023-06-26
Digital printing plates have requirements for CTP performance. As we all know, CTP process can bring many benefits for printing: excellent imaging quality, near perfect calibration, and fast production turnover. However, its various advantages are not only attributed to imaging equipment, but also depend on the quality and performance of CTP plates.
Here, we will focus on exploring several characteristics of the plate material and how they interact to assist CTP equipment in digital plate making, thereby affecting imaging quality. This applies to all CTP plates, but is particularly suitable for thermosensitive plates. At present, the use of global thermal plates is growing rapidly, and has also been recognized as the first choice for high-quality Planographic printing plates.
Requirements for aluminum based materials
In traditional plate making, whether the dot can be accurately positioned on the plate material largely depends on whether the position of the plate assembly and positioning registration device is accurate when using a vacuum pumping device or a continuous copying device. Anyway, this requires the plate to be quite flat when laid flat, but due to the direct contact exposure method used in the imaging process, the entire process can accept changes in the surface flatness of various types of plates, which are caused by the treatment of the aluminum substrate surface during the production of traditional plates. However, because the Digital printing plate is exposed by focusing the energy emitted by the laser light source, the requirements for the flatness of the digital plate, including the surface treatment of the aluminum base, are more stringent.
In addition, using energy focused imaging is different from direct imaging, which means that there will be no visible stripes when imaging on digital plates, as there will be no stripes generated during anodizing and polishing of aluminum plates.
When applying photosensitive emulsion on digital plates, it must be smooth, uniform, and free from defects. Because the dot size generated on the laser Computer to plate is very small, any dust in the air, no matter how small, falling on the plate in the process of reel production will cause this artificial image spot. In fact, irregular images can also be generated due to electrostatic spots, and they are very small and cannot even be seen with a magnifying glass used to inspect traditional printing materials.
The same uniformity requirements are also applied to the photosensitive coating of synthetic materials for Digital printing plates. Generally speaking, when the traditional printing plate is exposed under the ultraviolet light, the energy it receives is about 10000 times the energy transmitted by the laser system to the Digital printing plate coating in the direct plate making equipment. That is to say, in order to accurately meet the physical characteristics mentioned above, the emulsion coating of Digital printing plate must strictly meet the spectral sensitivity characteristics of a specific range, meet the requirements of synthetic substances (especially the molecular structure in the coating), and respond actively to energy. Therefore, factories producing Digital printing plates need special and additional chemicals, as well as special production workflow.
Operational requirements
Compared to traditional plates, CTP plates also require different operating methods during transportation. Because many digital plate imaging uses the edge of the plate as a key reference point for calculating the imaging position. Digital plates have very strict requirements for the straightness and uniformity of the edges. Although this is only a minor issue for traditional plates, if the digital plate edge
View More
