How to ensure the uniformity of UV UV curing ink ink color?
Printing is an important part of ensuring the uniformity of ink color, but also a process with strong technical requirements. Not only requires the operator to have a certain degree of professional knowledge and skills to adjust the machine, but also has a wealth of experience. To ensure the uniformity of UV UV curing ink color should be considered from the following aspects.
1) Printing pressure
Printing can not be separated from the pressure, in offset printing, the source of its pressure is the elastic blanket, followed by the pressure between the three cylinders of printing, between the ink rollers and ink rollers, ink rollers and printing plates, water rollers and water rollers, water rollers and printing plates between the pressure. They affect each other, together determine the amount of UV UV curing ink transferred from the printing plate to the print and the quality of the print.
① ink rollers and ink rollers, ink rollers and the pressure between the printing plate is generally used to adjust the thickness of the gauge, with the ink bar to check whether the ink rollers and printing plate contact is appropriate. If the adjustment is not proper or the inking time of the inking roller is not suitable, there will be ink bar, front light and then deep or front deep and then light, heavy shadow, flower plate and other phenomena. Rubber rollers are prone to thermal aging, resulting in surface hardening, cracking, peeling, affecting the transfer of UV UV-curable ink to the printing plate. Therefore, in the printing process should be replaced in a timely manner aging, hardening, cracking, shedding, not straight ink rollers, so that the UV UV curing ink transfer is good, the uniformity of ink color is guaranteed.
② water roller and water roller, water roller and the pressure between the printing plate is also dependent on the thickness of the gauge is not adjusted, the pressure adjustment between them is good or bad also directly affect the uniformity of the product ink color. If improperly adjusted, it will also cause the occurrence of water bar, paste plate, dirty, flower plate, UV UV curing ink emulsification and other phenomena. Well-regulated water roller, should be no UV UV curing ink back to the surface of the water roller, maintain good hydrophilicity, water transfer, to the printing plate uniform, stable water supply.
③ blanket in the process of reproduction of the image plays a role in accepting and transferring a certain thickness of ink film, both require it to be easy to ink, but also good ink transfer. Rubber cloth with a long time will become sticky, hard, elasticity, mechanical properties become worse, affecting its lipophilic and transfer UV UV curing ink printing performance. Therefore, in the process of use, should choose a good performance of the rubber cloth and the correct use of it, usually pay attention to the maintenance of the rubber cloth, to extend its service life, to ensure that it is the uniformity of UV UV curing ink transfer.
④ The pressure between the three rollers is measured by a micrometer after pressing the fuse. Improper adjustment will cause the cylinder slippage, thus increasing the friction of the printing plate, resulting in the flower plate, while making the graphics produce ghosting, too small print void and other phenomena occur.
2) water and ink balance
Offset printing can not be separated from the water and oil, too much or too little of both will bring trouble to the production, only the two maintain a relative balance, in order to make UV UV curing ink in printing to maintain relative stability. The following factors affect the water and ink imbalance.
① printing speed. Printing personnel know that the speed increases, the water transfer also increases, UV UV curing ink transfer rate decreases; speed decreases, increasing the UV UV curing ink transfer time, UV UV curing ink volume will increase. Need to print several hundred sheets of paper to reach a new balance, therefore, the printing process should be maintained in the printing speed of the smooth.
② UV UV curing ink additives. In the printing process, in order to facilitate the printing of smooth force to carry out, add a certain amount of UV UV curing ink additives to overcome the problems arising from UV UV curing ink viscosity is too large, add UV UV curing ink additives will also affect the uniformity of ink color. The more additives, the thinner the UV UV curing ink, transfer to the printing plate and the amount of ink on the paper is insufficient; conversely, the more ink transfer. Now most of a project needs to be completed by several machines together, each machine to add the same proportion of additives, so that the amount of UV UV curing ink additives added to the data.
③ printing machine idle. Printing process temporary stop is often occurring, generally is the paper delivery stopped, with the water roller is still running, with the water roller continues to pass the water bucket solution to the printing plate, but the water transfer roller because of the paper delivery stopped and automatically stop, with the water roller on the water is also reduced accordingly, UV UV curing ink viscosity in the idling process but a corresponding increase. At this time and then printed, the front of a few sheets of paper ink color darkening, to print a dozen sheets of ink color to reach a smooth. Therefore, the preparation work before printing should be done to minimize the number of stops.
④ scrubbing printing plate. Scrubbing the printing plate, the layout of the most water, UV UV curing ink viscosity affected by water, coupled with the cleaning of the blanket, UV UV curing ink amount to slowly increase, until dozens of sheets later to reach a balance. Therefore, when the printing press starts, should not sprinkle excessive water to the printing plate to wet the plate, reduce the number of times to wash the blanket.
⑤ in the printing process, the water roller will become increasingly dirty, attached to the UV UV curing ink more and more, so as to reduce the water received from the water transfer roller, resulting in water and ink imbalance. Low temperature and UV UV curing ink ”hard”, UV UV curing ink transfer difficulties, the machine to run for a certain period of time after UV UV UV curing ink to balance.
① Before printing must be identified sample, it is to ensure that the print ink color uniformity and some other quality indicators are in line with the requirements of the key, there is no sample of each machine can not start printing. In the printing process, to do three diligent, that is, diligent and sample control, diligent ink stirring, diligent control of water. Keep the batch product ink color uniform and stable.
② in the printing process, due to mechanical reasons caused by uneven UV UV curing ink, such as after the rolling teeth, chain teeth bite unevenly, the paper dump angle caused by ghosting, etc., reflected in the print is also uneven ink color.
③ encounter graphics side-by-side this version of the book, the number of prints is less, the number of sheets and more, to keep each print and between the print sheet and the print sheet UV UV curing ink color uniformity or more test operators. Due to the different location of the pattern, there is a pattern of places that require different amounts of ink, often just the ink teeth open flat a printing paper is over. Want to maintain the stability of the ink color, first of all, the printing plate should be classified, the pattern in the same position first, to avoid constantly repeat the adjustment of the ink teeth; secondly, the printing plate on the machine should be adjusted according to the pattern at the beginning of the ink teeth open ink volume, while playing the gauge according to the sample to adjust the amount of ink, this process over the plate paper to put a little more, to play a good gauge, ink color on its own there is no change; finally adjust the UV UV curing ink when Open small teeth, play a large file.
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