Discussion on the application of waterless offset

2022-10-13
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Discussion on the application of water free offset printing technology of optical discs IV

4. The advantages and disadvantages of non horizontal offset printing do not recruit patients

4.1 main advantages of anhydrous offset printing:

l) bright and bright colors and good consistency. The contrast of waterless printing is large. That is to say, the dark part is darker and the highlight part is brighter. The printing quality that traditional printing cannot reach can be printed. In the process of anhydrous printing, the color can come up soon, which can be registered immediately, and the color change is small during the printing process, which can maintain the consistency of the color,

2) good color saturation. The density of ink printed by waterless printing is high. Therefore, with the same number of lines, waterless printing is richer and more authentic than traditional printing. The four-color printing density is about 20% higher than the swop standard. Color restoration is more realistic

3) dot enlargement size, high resolution, good reproduction of details, and a sense of hierarchy. The waterless offset printing plate is a flat intaglio structure. The waterless printing plate layout is a non inking plane, and the layout is a "inking hole" structure. These "ink absorption holes" provide a supporting wall when the ink is transferred from the printing plate to the rubber drum. It can copy points from 2 ~ 3% of highlight to% of darkness, and the point reproduction range is 95%. Waterless printing not only expands the size of dots, but also increases the number of lines. Printing products with high number of lines can be printed, and the details can be reproduced well. The number of lines added to the waterless printing plate of Toray company can generally be 175 lines/inch, and some waterless printing manufacturers use 400 lines/inch

4) high production efficiency and short printing preparation time. Anhydrous printing simplifies the printing process from a chemical/physical change process to a pure mechanical process, so the printing speed of finished products is fast. The color adjustment method in the printing process is basically the same as that in traditional printing, so it also eliminates many factors that cause changes in the process and reduces the downtime caused by other reasons, which can be about 40% shorter than the preparation time of traditional printing

4.2 deficiencies of waterless printing

1) there is no horizontal printing, and the temperature and humidity requirements of the working environment are very strict. Generally, the ambient temperature area should be kept at 2, and the experimental report can be output and printed; Between 3 ℃ and 25 ℃, the relative wet area range is 55% - 60%. There are also some inks that require temperature control to be kept within the range of 15 ℃. The production practice shows that when the temperature is too low, the ink solidifies, and the ink delivery system of the offset press is blocked and cannot be printed; When the temperature is too high, "paste" occurs. At the same time, the number of faults caused by static electricity increases, which is prone to printing quality defects

2) the required ink viscosity is very high, and it is easy to adhere dirt (dust, fluff, filature, ink skin) on the ink roller, printing plate and rubber market. After getting dirty, the decontamination operation is cumbersome and difficult. It is easy to produce quality defects on prints

3) the quality of waterless offset printing products is mainly based on the assumption that the microcomputer has strong function and can be directly printed, which is reflected and adjusted by ink. Therefore, in addition to the quality of the ink, the pressure between the ink supply system, especially the ink rollers, is also important. The pressure between several ink rollers, between the ink rollers and the printing plate, between the printing plate and the blanket, and between the blanket and the substrate (CD) must meet the corresponding specification requirements. Excessive rolling is easy to cause ink bars, and it is also easy to dirty the layout. Too small rolling is easy to cause poor ink transmission, uneven ink color, and reduce the product quality. Therefore, the pressure adjustment between the ink rollers and the printing rollers must be done in strict accordance with the requirements

4) the silicone layer is not resistant to friction and is difficult to repair. The silicone rubber layer on the non graphic part of the waterless printing plate is easy to be scratched, exposing the photosensitive resin layer that absorbs ink under it. At this time, its special revision solution (a kind of liquid silicone rubber) is needed to repair the scratched part. But because it is a little delicate. The operation is difficult

(author: Yang Deshun)

source: recording media technology

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