The printing process is a special printing technology that has just been introduced to China in the 1980s. Due to its obvious advantages in printing on small-area, irregular-surfaced products, it has made up for the deficiencies in screen printing processes and, as a result, has developed very rapidly in recent years. . In the early 1990s, with the further opening up of the Chinese market, a large number of foreign-funded enterprises with electronic products, plastics, gifts, toys, and other traditional industries as the main products entered the Chinese market one after another. Pad printing technology and screen printing technology as the main decoration methods were obtained. Extraordinary development, according to incomplete statistics, the use of pad printing technology and screen printing technology in the above industries reached 27%, 64%, 51%, 66% respectively.
There are many similarities between pad printing process and screen printing technology. For example, it is widely adaptable to printing materials; there are many types of inks, and printing inks and screen printing inks can be basically used; it can be very conveniently completed by replacing fixtures and printing plates. Different products such as printing. Therefore, in many cases, pad printing technology and screen printing technology are inextricably linked and play an important role in special printing. Because pad printing technology and screen printing technology are so close, most printing experts classify it as the field of screen printing. Inspecting, there are no special institutions for the study of pad printing technology, and there are no institutions that specifically investigate the distribution of pad printing technology in the market. Many data concerning pad printing companies cannot independently reflect the actual situation of pad printing technology. .
However, there are many differences between pad printing and screen printing, such as: the ink transfer process is obviously different; the structure of printing presses is different; the types of substrates are also very different; in fact, the difference between them is far greater than the similarities. We used to bundle them together because they faced a common market. In this common market, printing is inseparable from screen printing, screen printing is also inseparable from printing. It is difficult and unnecessary to peel off printing from the screen printing industry. However, if we want to understand the current status of the printing process technology, we cannot look at it from the perspective of the screen printing industry.
We all attributed the printing of paper to mainstream printing, and mainstream printing has always been highly valued by the theoretical community. In recent years, screen printing has received attention. The primary reason is that its printing advantages in paper are discovered rather than people's attention to printing. The range of advantages, such as: the use of screen printing to complete the UV part of the paper, special UV inks such as coral ink, ice ink, wrinkle ink printing to print, flexographic printing has a better effect.
Pad printing technology has not been so fortunate. While all printing processes are exploring their respective advantages and becoming integrated, pad printing technology still maintains its independent identity. The link between paper and pad printing technology is still blank, but pad printing. Technology does not stop its rapid growth, because the areas that printing technology is good at cannot be accomplished by any other printing process. The prosperity of the Pearl River Delta industry supports the high growth rate of the printing industry at an annual rate of 18%. Every year, the employment opportunities created by the printing of technology-related industries have also been of concern to government agencies.
In general, the technical level of the pad printing process is not high, and it is very difficult to continue to develop in the case of high production costs in developed countries. Therefore, the pad printing industry has shifted to low-cost developing countries such as China. It is an inevitable trend. At present, in addition to the few foreign companies that also manufacture highly automated printing lines, most companies have moved their production bases to China. This is a historic opportunity for China. What is the current level of development of the printing process in China? Where is the latest development? The superficial ideas in this article hope to bring some help to the readers.
Plate making
Platemaking is the prelude to printing. The traditional printing is not realized by first transferring the graphic on the manuscript to the surface of the printing plate. In terms of printing plate making, it should be a combination of intaglio plate making technology and corrosion signboard technology. . The gravure plate making technology has now developed into electronic engraving and laser engraving, and the corrosion of the signboard has also gradually eliminated the acid etching technology. However, the printing plate making still remains in the very old process, which is related to the conditions of the pad printing technology itself. The first is that the cost of the printing process is relatively low, and the use of electronic engraving and laser engraving is too expensive, and the average enterprise cannot afford it. Many companies proposed electrocorrosion technology, but no modern warfare enterprise's technology can ensure that the corroded plates can be printed. The process of acid corrosion is easy to grasp and low in cost. Despite severe environmental pollution, it is still used by most enterprises.
Printing steel plate
The use of pad printing plates in the pad printing process occupies a dominant position. 100% oil pad printing machines and 16% oil pad printing machines use thick steel plates with a thickness of about 15 mm; another 77% oil-filled type Pad printing machines use thin steel plates with a thickness of 0.25 mm and 0.5 mm. Whether they are thin or thick steel plates, the plate making process is the same. The substrate used is also about the same. The steel plate must have a fine structure and the surface finish should be sufficiently high. The former guarantees the regularity of the edge of the image after etching, and thus ensures the integrity of the dot structure, so that the trimming sharpness and color reproduction of printed graphics and texts are achieved to the utmost extent; the latter ensures the cleanness of the scraping ink and the durability of the ink. Thickness of the thick steel plate used on the ink pad printing machine requires higher surface tolerances. Excessive surface tolerances on the one hand accelerate the wear of the oil squeegee, and on the other hand, it also affects the sealability of the ink. It is used on an oil pan type pad Printer. If the steel plate is to be used on the oil pan machine, it is necessary to ensure a higher surface finish and a lower flatness tolerance.
The thin steel plate has a better flexibility, so the degree of cleanness of the scraping ink is easily ensured, but this is related to the manufacturing precision of the substrate supporting the thin steel plate. The tolerance of the surface roughness of the substrate is unsatisfactory, and the ink leaks during sliding of the oil file and the steel plate. Another factor is the manufacturing precision of the sliding guide shaft of the oil rake, such as the surface roughness and fit tolerance, which is reflected in the index of the assembly level of the whole machine. It is important to control how the tolerance of the parallelism between the guide shaft and the steel plate is controlled. From this point of view, it is More difficult to manufacture thick plate ink pad printers.
Resin Edition
The application of the resin plate to the pad printing process is not long, but it has been paid attention to. The resin plate is mainly made of nylon sensitized plastic and cast on the surface of the zinc plate, similar to the resin plate used on the sticker trademark. Nylon has very good abrasion resistance, and it can withstand the repeated rubbing of oil rakes or squeegees after curing. The advantage of using a resin plate is that, first of all, it is easy to obtain extremely fine dots. When printing delicate small items, the use of a resin plate is preferred. If it is said that the manufacture of ink pad printing machine reflects the manufacturing level of a company, it will be more difficult to manufacture a pad printing machine using a resin plate. After all, a nylon photosensitive adhesive belongs to a polymer material, and when the manufacturing accuracy of the substrate supporting it is poor, printing is performed. It is not easy to complete general printing. The surface state of the polymer material is very fine, and slight defects will seriously affect the printing quality.
Platemaking process
At present, the production of pad printing steel is mainly performed by using a nitric acid solution and a ferric chloride solution added with a protective agent. The acid odor of this kind of corrosion is very unpleasant. The formation of nitric oxide and nitrogen dioxide is very harmful to the human body. The development of the steel plate after corrosion is mostly using hydrogen peroxide as the main chemical solvent, and it also has a certain amount of human skin. damage. Therefore, it has long been banned in European countries. They started using resin plates or laser engraving to make plates. Corrosion-resistant steel plates should be regarded as a relatively novel idea to be used for corrosion-free zinc plate corrosion-free machines. Some manufacturers have already succeeded in trial production. This method greatly reduces environmental pollution. The resin plate is much more environmentally friendly and safer. The resin version uses a nylon emulsion that can be developed with sprinkling. With the popularity of digitization, the time for digitally printing a resin printing plate will not be long.
(to be continued)