Valve bags are commonly used in daily life, especially on construction sites of some engineering projects. Of course, valve bags can not only contain putty powder, tile glue and other construction materials, but also can contain corn flour, bread flour and other foods. The main function of the valve bag is to make a medium-sized bulk container, which is convenient for packaging, transportation and stacking storage. It is often used for the sub-packaging and transportation of powder or small particles. During use, the valve bags may be found to be white. What is the reason for the valve bags to be white? How to solve it?
1. Printing ink quality
In most cases of printing whiteness, it is due to the low viscosity of the ink, which is mainly due to the influence of printing quality. The color of the pattern on the printed package is light, and the printed whiteness is needle-like, and the printed pattern is very false.
Solution: When printing whitening occurs, it is necessary to consider measuring the viscosity of the ink, which can be improved by increasing the tackifier in the ink or adding new ink.
2. Paper material
The whitening that appears under the influence of the paper material is mainly manifested as the deinking of the printed pattern. If the color block appears white and it is mainly manifested in the middle of the paper, it may be that the ink absorption of the paper is poor, and the ink cannot normally penetrate into the paper. . At this time, rubbing the surface of the valve bag by hand will cause the ink to fall off.
Solution: In this case, do not always increase the printing pressure and plate pressure when printing whitening. It can be improved from the ink aspect. Increasing the resin content and penetrant in the ink can better solve the problem of paper whitening.
3. Insufficient pressure
Insufficient printing pressure is also one of the reasons for whitening. The printing pressure here refers to the pressure of the pressure roller and the printing cylinder. Insufficient printing and insufficient plate pressure cause valve pockets to be white. The reasons are similar, but there is a difference in the printed pattern. There is no unevenness on the cardboard, and there is enough ink on the printing plate.
Solution: The solution to this type of whitening is to adjust the pressure of the printing roller and printing cylinder, and adjust the pressure to a suitable position to solve the problem of whitening.
What is the reason why the valve bag is exposed? Mainly focus on the above three types. Although the valve bag is just a packaging tool, its appearance also directly affects the intuitive judgment of buyers and users on the product. For this reason, the phenomenon of valve bag exposure should also be paid attention to.