On the high-tech and operation points of the hotte

2022-09-22
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High tech and key operating points of flexographic printing (Part 1)

flexographic printing, derived from relief printing, has been developed and improved for more than 100 years. It has continuously absorbed and applied advanced technology to improve printing quality. Now, excellent flexographic printing products are completely comparable to offset printing, marking the beginning of a new milestone of flexographic printing. In recent years, flexographic printing has increased at an alarming rate of 70% every year, and now accounts for more than 20% of the global printing market. According to experts' prediction, by 2005, the flexographic printing market is expected to rank second among all printing formats. Throughout the remarkable improvement of flexo printing quality, the key is the application of high and new technology, so that the overall technical level and material quality can be continuously improved

I. digitization and laser technology in plate making

the high and new technology of plate making is computer direct plate making (also known as laser direct plate making or digital direct plate making, i.e. CTP), whose core process is derived from the laser technology that appeared in the 1960s. After the 1990s, with the research and development of computer technology, equipment and materials, CTP technology has matured and continued to show its advantages, accelerating the research, development and industrial application of CTP technology. According to statistics, by 1997, 65% of large printing plants in the United States had used CTP technology. From 1995 to 2002, the application and popularization rate of CTP increased by more than twice every year. Direct plate making by computer can improve the speed of plate making, improve the quantity and quality of plate printing, which is beneficial to environmental protection and get rid of darkroom operation. Today, CTP technology has shown its advantages in lithography, and its market share is expanding. With the improvement of its technology and CTP plate quality, its market prospect is very broad. It can also be said to be an important direction for the development of the printing industry in the future. Using CTP technology, it can be printed not only on paper, but also on other printing materials, such as various plastic films and composite films, metal sheets, wood, glass, ceramics, textiles, etc

digital direct plate making was first studied and used in other printing processes. Flexographic plate making is the last printing method to transition to film free plate making in various formats. This is because flexographic plate has a certain thickness. If you want to expose digital information directly on the plate through high-speed laser, it determines the structure of the tension machine to obtain solid points. It is conceivably much more difficult than lithography. However, various constraints of traditional plate making methods, such as: plate making with film requires multi-channel image processing, which is not only poor in stability, but also high in cost. In addition, temperature and humidity have a certain impact on the film, while maintaining the shrinkage and hydrolytic resistance similar to the traditional heat-resistant nylon 66, and sometimes you have to guard against scratches and scratches on the film; When the film and plate are closely exposed, the image quality may be damaged due to light diffusion or poor sealing, and the tone of the fine part cannot be reproduced; Because smaller dots are difficult to print, they can only be printed with thick lines. Therefore, flexographic printing can only linger in the production of low-quality products. With the introduction of flexo direct plate making machine, the image is directly exposed to the flexo plate, which overcomes the above adverse factors caused by the use of film. The flexo plate used for direct plate making is different from the ordinary plate. Its surface is covered with a layer of melting layer - synthetic carbon film, which can be combined to form a carbon film and avoid dust particles at the same time. During laser scanning, the overlay at the light spot is melted and evaporated without leaving any trace, which is equivalent to leaving a very clear negative picture on the surface, and then the back of the flexo is still exposed in the usual way so that no impurities remain in the tube (at this time, the exposure time determines the thickness of the plate). Main exposure (the light source directly exposes the photosensitive polymer at the lower layer through the melted opening on the synthetic film, so there is no scattering or diffuse reflection, so the edge of the point is smoother and sharper. Moreover, even if the exposure time of the digital plate is long, it will not make the point shape virtual), The corrosion treatment was carried out after Hangxiao steel structure, the first steel structure national housing industrialization base in China, is located in Hangzhou, a new industrialized steel structure building production and manufacturing base

The application of CTP technology can solve some troubles caused by material and technical problems in conventional film plate making. For example, excessive back exposure time causes inconsistent thickness of lower base of relief, insufficient back exposure or main exposure time causes line deformation and point loss, excessive main exposure time causes shallow negative image, error of post exposure causes too high hardness of printing plate, insufficient plate washing time causes inconsistent thickness of lower base of relief, long plate washing time, high brush pressure causes line deformation and point loss The non photosensitive material is not completely dissolved, resulting in a shallow negative image, etc. With the continuous deepening and improvement of the research on CTP technology and related technical materials, its advantages will become more apparent. It can not only save time, manpower, materials and other resources, improve the quality of printed matter, reduce environmental pollution, but also streamline and optimize the process flow, and it is easy to set up a high degree of automation continuous production line. Combined with advanced computer technology, it is believed that, CTP technology will bring a new revolution to flexographic printing

(to be continued)

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