There are many kinds of printing and whitening, how to quickly identify and treat the right medicine?
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There are many quality problems in the printing process, such as printing paste, printing deinking, printing whitening, etc. Among them, printing white is a common problem. In actual production, there are many reasons for printing whitening. This article focuses on how the printing staff should quickly find the type of printing whitening and the right medicine.
Printing whiteness seriously affects the printing effect
Printing white is the most common and most difficult quality problem in corrugated carton production. The printing whiteness seriously affects the printing effect, which not only causes the printing on the surface of the carton to be unsightly, but also appears to be a non-conforming product if a large area appears white, resulting in waste of production.
Paper water absorption, ink viscosity, printing pressure, etc. will cause printing whiteness
There are various reasons for the occurrence of printing whitening, such as paper water absorption, ink viscosity, printing pressure, paper dust on cardboard, dust, and the like. Of course, the reasons for the printing white are different, so the way to solve the problem is naturally different!
Different printing and whitening performance, coping with the drug
As a printing staff, how to quickly find a solution to the problem of printing white? The causes of printing whiteness are often different, and the appearance of whitening is also slightly different. The printers need to learn to judge the crux of the printing white according to the appearance, so as to deal with it quickly. The following highlights the three most common whitening phenomena and solutions.
1 Dew white caused by improper pressure adjustment
(1). The pressure of the plate press (upper press) is not white (the pressure of the printing cylinder and the anilox roll): there is an imprint of the indentation on the cardboard, which has a concave and convex feeling.
The pressure of the plate press (upper pressure) is not obvious. The printing surface is incomplete, the printed pattern is smooth and the printed pattern has an indentation on the cardboard. As long as the white paper is printed by hand, the cardboard can be found here. There is a feeling of bumpiness. Once this phenomenon occurs, it means that the plate pressure is insufficient. If the printing unit is separated and the printing layout is viewed, the insufficient amount of ink on the printing surface is also the insufficient pressure of the printing plate, resulting in printing whiteness. Generally, the printed white area will be relatively large.
(2). Insufficient printing pressure (pressure roller and printing cylinder pressure): There is enough ink on the printing plate, no bumpiness.
There is a similar difference between the printing pressure and the whitening phenomenon, but there is a very obvious difference, that is, the printing pattern has no unevenness on the paperboard, and there is enough ink on the printing plate.
Improvement method: The best way to solve these two kinds of whitening phenomenon is to adjust the pressure to the appropriate position, which can directly improve the printing whitening phenomenon.
2 The viscosity of the ink is low and white: the color of the printing pattern ink is light, showing pinhole phenomenon.
The ink viscosity is low and there is a phenomenon of printing whiteness. The most obvious is that the ink color of the printed pattern is light, and the printing whiteness shows pinhole phenomenon, and the printed pattern is not real.
Improvement method: The appearance of such whiteness firstly measures the viscosity of the ink. It is possible to add a tackifier or add some new ink to the ink to solve the printing whitening phenomenon.
3 The reason for the paper is white: the print pattern is deinked
The phenomenon of printing whiteness caused by paper is mainly reflected in the deinking of printed patterns. If it is a white block phenomenon, it is mainly reflected in the whiteness of the middle part of the paper. Because the ink absorption of the paper is very poor, the ink cannot penetrate into the paper. The ink floats on the surface of the paper, and the ink is peeled off as long as it is rubbed by hand.
Improvement method: If you encounter such printing whitening, do not always add printing pressure and plate pressure. It is necessary to work from the ink side to increase the resin content and penetrant in the ink. This method is more effective than other methods.
The phenomenon of printing whitening and solving the phenomenon of printing whitening are far more than these aspects. The above four are the most common printing white phenomenon in the production process.