In the next five years, the digital development of the international printing industry is a foregone conclusion, and China must accelerate the digitalization of the PS version of the manufacturing industry. The relevant experts in the printing industry pointed out that since the 1990s, the world printing industry has basically reached a stage every five years: in the early 1990s, the most notable was the desktop publishing system, and soon the color desktop system was introduced: in 1995, Digital printing and Computer To Plate (CTP) technologies have emerged; by the year 2000, digital integrated workflows and cross-media technologies were introduced at the largest international exhibition in the world's printing industry. In short, digitalization and its more in-depth development have become the inevitable direction for the future development of the printing industry. We believe that China's PS plate manufacturing industry, which has grown up and grew up in the market economy, will certainly be able to meet the challenges, continue to grow, accelerate the digitalization process, and become an excellent industry that can compete with foreign developed countries in China's printing industry.
III. Introduction of the most common CTP plates at present. Silver Salt Plates The silver plated CTP plate is the most active plate in the direct plate making version. It was originally coated with a silver layer on the diazonium salt layer of the current PS plate. The salt photosensitized layer, after laser exposure → silver salt development → full UV exposure → diazonium salt development process, finally obtains a plate that can be printed on a machine, and its printability is the same as that of the current PS plate. However, due to the more complex development process, it affects its further application. In recent years, a silver salt CTP plate has been developed for direct silver salt coating that requires two exposures for secondary development in two days, thereby greatly improving the application of the CTP silver salt plate.
Thermal plate thermal imaging layer consists of heat-sensitive resin and infrared beam material, which is named because it is used in the visible light area of ​​exposure. In the 1980s, the infrared laser source has been relatively mature, and the temperature of the thermal light source is usually 800-1080. between. The heat-sensitive coating can absorb infrared heat energy and transfer the heat-responsive resin to cause cross-linking or decomposition reaction, thereby forming positive and negative images on the plate.
In recent years, the thermal CTP plate has developed rapidly. It is favored by excellent imaging performance and excellent operating performance that are unmatched by other plates. At the same time, lasers that are also associated with them are closely linked in terms of technological maturity (high power, high stability, and acceptable price) and the widespread use of multi-beam scanning technology. It can be said that this status quo indicates a development trend of today's CTPlate technology.
In principle, thermal imaging is a low-sensitivity imaging system. Generally, the minimum imaging energy is in the range of 102-103mJ/cm2. Sensitivity is tens of millions to one millionth of the sensitivity of silver salt-based CTP plates, even The photosensitivity is lower than that of the conventional PSA version and is not suitable for high-speed scanning imaging applications such as direct manufacturing. However, the power of near-infrared lasers (such as LD) has increased from the initial number of mW/cm 2 to several W/cm 2 in the past 10 years, which is an improvement of 103 orders of magnitude. The scanning beam has also grown from the original single beam to dozens to hundreds of beams today, an increase of 101-2 orders of magnitude. Therefore, the sensitivity requirement for the CTP plate material is also reduced correspondingly by 3-5 times, that is, the recording material with the minimum imagewise exposure amount in the range of 102-103 mJ/cm2 (such as the thermal recording material) also falls within the range of the CTP plate material. The imaging performance, post-processing performance, and operational performance of the recording material were leaped to the main technical parameters. This has made it possible for thermal imaging systems to be used in CTP technology, and it has seen rapid development. Breaking through the gap of sensitivity, the wide-spectrum color-sensing range of the thermographic imaging center, the fixed and non-accumulated effects of the rubber energy threshold, and the need for complicated post-processing (even no post-processing) and open-room operation characteristics have become The advantages of other direct printing plates are far behind. For example, Dainippon Screens Corporation (DS) exhibited and PlateRite 8000, a thermal imaging platesetter, used 32 laser scanning imaging, and it was said that it could achieve an output speed of 12 plates per hour.
The family of thermal plates has developed extremely rapidly in recent years, showing its strong momentum of development. Thermal imaging media from the imaging mechanism, there are thermal crosslinking, thermal decomposition, thermal ablation and thermal affinity changes in 4 kinds; from the type of media, there are two types of negative and positive images: from the follow-up processing From the processing point of view, there are three types of preheating (Preheat), no baking before development, and no need of development before development; from the viewpoint of printability, there is a thermal type thermal plate using traditional offset printing water. There are two types of dry plates (waterless offset plates) that do not require dampening water. Among the various types of plates, thermal plates that do not need to be developed are considered to be the ultimate destination for thermal plates. At present, these types of plates include Press Gold's Pearl Gold and Asahi Kasei's Thermal CTP plates. The former is a waterless offset plate using thermal ablation imaging principles. Although this plate does not require any post-development processing, it must seek to remove and recover the shards generated by the thermal ablation of the scanning image, which would otherwise constitute a contamination of the imaging device and the environment. The latter adopts the imaging principle of thermal affinity change, and the heat affected area changes from hydrophilic to lipophilic. It is an ideal direct plate that does not require development and does not produce production pollution.
Inkjet Direct Plate In the CTPlate family, there are two relatively new members worth mentioning. One is the scanning imaging principle of a combination of a focused UV light source and a digital LCD panel exhibited by Toyo Ink Corporation. The conventional PS can be used. A version of the Platesetter, the UV-Setter-710HS; another is a direct plate-making system (currently having a resolution of 600 dpi) that is exhibited by Hitachi Koki and uses inkjet printing imaging technology. (To be continued)