Packaging printing is a printing method and post-press processing technology used for the main purpose of beautifying, identifying and promoting commodities. I believe everyone is familiar with them, and the two are inseparable. The following editor will introduce to you how to do color processing in printing:
In the process of lithographic offset printing, the phenomenon of false color printing is often encountered, which is mainly manifested in the fact that the solid part of the printed product has spots or voids, the graphics or lines are incomplete, and the reproducibility of the tone level of the image is poor or the dots are lost. There are many reasons for the false ink color in the printing process, and there are many factors involved, including the performance of the paper, the performance of the ink, the quality of the printing plate, the quality of the printing blanket, the printing pressure, the performance of the printing machine and the printing process, etc. .
If during the printing process, the performance of the paper and ink is stable, the quality of the printing plate meets the printing requirements, and the working performance of the printing machine is relatively stable, there is still a phenomenon that the ink color printing cannot be realized. The main reason is the problem of printing pressure. . In offset printing, the size of the printing pressure directly determines the transfer of ink during the printing process. If there is local uneven pressure during the printing process, it will lead to unrealistic printing ink colors.
In offset printing, the compression deformation of the blanket is the fundamental guarantee for generating printing pressure, and the transfer of printing ink is the result of the compression deformation of the blanket. Therefore, the size and uniformity of the printing pressure are directly related to the blanket used for offset printing.
The blanket wrapped on the roller is affected by its own tension and printing pressure. With the continuous increase of the number of rolling, the stress of the compression deformation of the blanket will accumulate, and the blanket will become stiff and lose its original softness. High elasticity and high elasticity, even bright or cracked traces may appear on the surface of the blanket, resulting in local unevenness of the printing pressure during the printing process.
On the other hand, since the blanket cylinder is installed between the plate cylinder and the impression cylinder, each tiny unit on the blanket needs to be in contact with the two cylinders once per revolution. Therefore, its force changes periodically. It is precisely because of the periodic change of the force on the blanket that it will cause internal friction of the blanket, which will lead to the aging of the blanket, affect the uniformity of the printing pressure, and may lead to the scrapping of the blanket. Especially on modern high-speed offset presses, the frequency of the force cycle of the blanket is higher, the internal friction generated by the blanket is greater, the life of the blanket will be shorter, and the impact on the printing pressure will be greater.
In addition to providing printing pressure for offset printing, the blanket should also have a good ability to transfer the ink from the graphic part of the printing plate to the surface of the substrate under the action of the pressing force, that is, the ability to receive and release ink. However, the aging of the blanket will change the ability of this ink to transfer, and it will also lead to the phenomenon of false ink color.
