The disadvantages of waterless offset printing
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As an emerging printing technology, waterless offset printing technology was introduced to China in the early 1990s, which has aroused widespread concern in the printing industry. However, due to various reasons, it is only used in a very small number of places in China. By using this printing method, the feeling is better and the corresponding economic return is achieved.
Waterless offset printing
In the early 1960s, 3M Company of the United States first patented and industrialized waterless offset printing technology. The emergence of this technology caused great shock in the world printing industry, but some of the technical problems were not solved well. By the early 1970s, 3M Company terminated the production of waterless offset printing plates, but the idea of this technology inspired many researchers in the printing industry in the world. They actively and continuously explored and progressed along this line of thought. Unremitting efforts, no water Printing technology has made great progress. Among them, Toray Co., Ltd. first industrialized the waterless offset printing plate and disclosed the patent. In the mid-1970s, Toray's waterless offset printing plate was officially sold. In addition to a lot of work on the plate, they also made great efforts in the ink. After repeated improvements, 3M companies encountered problems such as development, film strength and storage stability in the production of non-watermark plates. Solved, its company has been in the leading position in the field of waterless offset printing.
From the 1980s to the 1990s, Nikko Xiangtang Co., Ltd. changed the water printing to waterless printing within the company and realized the computer management of production scheduling control. The company has long been the authoritative developer of waterless offset printing technology as a technical consultant. The adoption rate of waterless offset printing in the company reached about 85%. The company's product quality level and economic benefits have been greatly improved. In the mid-1990s, Wenxiangtang Co., Ltd. and Beijing Foreign Language Printing Factory jointly established Beijing Wenxiang Color Printing Co., Ltd. At the beginning of the establishment, the company mainly used waterless offset printing technology and became the experimental field of China's waterless offset printing technology.
Waterless printing is divided into: from the first generation in 1977, the second generation in 1987 to the third generation in 1994, there has been a rapid development since the industrialization: a new generation of waterless offset printing machines, Ink and plates are constantly being developed. In the past two decades of waterless printing changes, the changes in equipment and raw materials are only the continuous improvement and improvement of this printing method. The most original first-generation method used by Wenxiang Color Printing Co., Ltd., which belongs to the waterless printing company, is the waterless printing using the non-cooling printing machine. It is because of this that the waterless printing is the emerging printing. The advantages and disadvantages of technology are fully reflected, allowing users to experience the essence of waterless printing in the actual work.
Waterless offset printing principle and process
Anyone who has been in contact with printing knows that lithographic offset printing adopts the principle of ink and ink repelling. On the same metal lithography, there is both water and ink, so the key factor in printing the quality of the product is water. The balance with ink, and the water supply system is a direct factor in many of the drawbacks of water printing.
Waterless printing, as its name implies, is a factor that removes water compared to the current lithographic water offset printing. Its basic characteristics are: 1 faithfully reproduce the image on the negative image on the waterless offset printing plate. 2 faithfully reproduce the image of the plate on the substrate. Simply put: the waterless offset printing plate uses the oil-repellent property of silica gel. The waterless plate is coated with a layer of silicon germanium on the photosensitive layer, and the unused plate is exposed before exposure. Adhered firmly to the silicone layer. After the printing plate is photosensitive, the photosensitive portion (non-image portion) generates a light polymerization reaction, and the upper silicon germanium rubber layer is adhered and fixed.
The key to the development of waterless offset printing plates is to cut off the silicone layer equivalent to the image portion. The shearing force is stronger than the adhesion between the silica gel layer and the photosensitive layer in the image portion, and the gel layer can be removed by applying it to the interface of the two layers. Of course it is first to use the appropriate P. P. G (polypropylene glycol) and P. E. G (polyethylene glycol) swells the photosensitive layer of the image portion (unexposed portion), the silicon germanium layer floats, and after the adhesion between the two layers is greatly weakened, the shear is applied using a nylon brush. The silica gel layer is applied to the interface to remove it, and the water-free version is thus produced.
Advantages and disadvantages of waterless offset printing
In order to make the printed matter closer to the original, the printing density of each color is higher than the original set density. The key of its technology is to control the expansion of the dot, and the means for controlling the dot expansion is to modify the tone curve during the plate making process, and the second is The exposure time is controlled during the printing process, so that the printing plate dots are slightly reduced. This is a commonly used method with water version, and the waterless offset printing plate is a flat intaglio structure, which can replicate from 2 to 3% of highlights to 97-98% of dark shades, with a dot reproduction range of 95%. In the non-horizontal printing, the amount of dot enlargement is small due to the absence of the effect of dampening solution, and the amount of dot gain of the intermediate tune is about 7-8%. This amount does not change greatly even when the thickness of the ink is increased. The gradation copy curve waterless offset printing plate can obtain a copying effect similar to that of the original film compared with the PS plate. Therefore, it is shown that the waterless offset printing is obviously superior to the water offset printing for controlling the dot gain.
Due to the removal of water, the product's dot ink is full, and the graphics are bright and colorful. It eliminates the unevenness of the ink color caused by the water, the emulsification of the ink, the water point, the dirty side of the surface, and the water roller bar printing. In addition, the adjustment and maintenance of the water system can be omitted in the adjustment of the machine. There is no water factor, no need to damp the potion, water roller system and related accessories. Therefore, the preparation time before starting is shortened, the paper consumption is saved, and the printing cost is reduced.
Under the premise of ensuring the environment required for waterless printing, due to the special structure without watermark version, the printing durability is improved, and currently it is generally around 100,000 impressions or even higher. When the printing plate needs to be retained, it is not necessary to wipe the glue. It is only necessary to clean the used printing plate with gasoline and save it in the dark. It is easy to retain and the retention period is much longer than the watermark version.
In the small-volume printing industry, the compatibility of waterless printing is good. Even if the waterless printing equipment is developing rapidly, as long as you have water printing equipment and machinery, you can change to waterless printing without using water roller. At present, our company's waterless printing equipment is the original water printing machine produced by Komori, Japan, and the printing effect is also ideal, with the most outstanding performance in spring and autumn.
Since the waterless printing technology is obviously simpler than water printing, it is convenient for the operator to master the technology, which is favorable for the quality of the printed product to be stable and reduce the labor intensity of the worker. Reduces the erosion of water on printed mechanical parts, especially several rollers, extending the life of the machine.
The number of machine operators was reduced. The four-color four-color printing press used by the company used waterless printing, including the leader, from the original four people to the current two.
There are still many imperfections in waterless printing. For example, since the paper used for waterless printing is the same as the paper used in other printing methods we usually use, when using a non-dedicated waterless printing machine, the required ink viscosity is high, so that the paper is plucked and rubberized. Unavoidable, at this time, the phenomenon of static electricity is also very easy to appear, so the humidity of the printing peripheral environment is relatively strict, (in which 100g or less or offset paper is more obvious), the humidity is generally required to be between 50% and 60%. Therefore, the company is easy to master the wet temperature in spring and autumn in waterless printing.
Temperature control is more important in our company, because the company uses non-cooling type, the ink splitting causes heat, easy to make the ink soft, and the printing plate is dirty, so in the first generation of waterless printing, The ink has H, M, S, that is, hard, medium and soft, so that it can be used for different seasons or small temperature changes. The temperature of the external environment during printing should also be controlled at 18 °C to 22 °C. It is appropriate.
The quality of waterless offset printing products is all reflected by the ink to adjust. Therefore, in addition to the quality of the ink, the pressure between the ink supply system, especially the ink roller, is also critical. At the same time, the pressure between several rolls is also quite demanded. Excessive roll pressure is easy to cause the ink bar, and it is easy to cause the plate to be dirty. If the roll pressure is too small, the ink transfer will be poor, and the product quality will be reduced. And the adjustment of the pressure between the printing rolls must be strictly in accordance with the requirements.
For defects or residual coating portions of the waterless plate layout, a special decontamination solution can be applied, and defects can be eliminated by means of a new silicon germanium film formed. The decontamination liquid is a polycondensation cross-linking type silicon-silicone liquid which is decomposed by water in the air, and a special coating tool must be used in order to achieve stability during storage and special characteristics after coating; In addition, in the coating, that is, "dirty", it is necessary to master the thickness of the coated silicon sputum. If it is thin, it will not be dirty or it will be rubbed off quickly after printing and pressing, so that the coating layer is too high. The original silica gel layer higher than the non-image portion causes the scratching of the ink to be dirty and deviates from the original intention of coating.
At present, non-developed countries in the printing of non-developed materials such as plates and inks must rely on imports, and the relative cost is relatively high. As for the use of the company, an unseasoned waterless four-open royalty is nearly 90 yuan. The PS version of a joint venture is only about 20 yuan.
Waterless offset printing market and analysis
At present, there is a rapid development of new technologies and materials for waterless printing in the world. The use of waterless offset printing is also increasing. In Japan's letterpress companies, waterless offset printing technology has been used on high-speed rotary presses. According to some data, the market share of waterless offset printing in Europe is now 6% to 7%; 5% to 6%, according to reports from Germany's FOGRA: the market share of waterless offset printing will increase to 10% by 2006, and the waterless offset printing market in Asia has a considerable share in printing in Taiwan. In addition to the proportion, some countries in Southeast Asia also have a small number of applications (there are no specific reports). In China's mainland, except for one or two provinces and cities such as Beijing, there are no other places to use, and the market share is about a few tenths of a million. Therefore, waterless offset printing technology can only be regarded as a new technology in China. Why has there been no progress in the Chinese printing industry since 1993? The reason for the analysis is mainly because the localization of the plate material has not been solved. The cost of importing from Japan is 3-4 times more expensive, and the cost of ink is also 30% more expensive. Therefore, many enterprises are in the period of continuous decline in the printing industry. Waterless offset printing technology can only be discouraged.
Edited
In summary, the advantages of waterless printing outweigh the disadvantages, and the economic benefits are obvious. If the printing company adopts this new technology, it will inevitably lead the company to take the lead in quality and timeliness in the fierce market competition. Waterless offset printing has a lot of room for development, especially in China, with the improvement of people's living standards. The requirements for print quality will be higher and higher, and prints are not only simple bamboo image reproduction. It is increasingly being appreciated as a special piece of art, so it has a wide range of sizes, short time, rapid and large-scale reproduction, and water-free printing with high-quality reproduction levels will certainly be widely adopted. The prospect of waterless offset printing is bright.