How to solve the problem of white spots in the process of self-adhesive Labels printing

How to solve the problem of white spots in the process of self-adhesive Labels printing

Printing white spots is a common problem in the process of self-adhesive label printing. Mr. Qiang Yongsheng, technical service manager of Dongguan Ande Label Materials Co., Ltd., based on the experience collected from customers over the years, summed up the causes of white spots in the printing process of self-adhesive materials, and proposed corresponding solutions. share.

In general, there are four main reasons for the white spot problem in printing: rough label material, powder drop from the material, static electricity and dust in the workshop environment. This article will give solutions to the above four problems.

1. White spots caused by rough surface of the material

At present, in my country, the printing of self-adhesive labels is mainly based on letterpress and flexographic printing. These two printing methods have high requirements on the surface roughness of the self-adhesive material. For example, for the surface material of coated paper, if offset printing is used, the surface roughness (the difference between the height of the material surface) can be less than 1.4 microns; but when using letterpress and flexographic printing, the surface roughness needs to be less than 0.7 microns to ensure printing There are no white spots during the process. This is because the printing pressure of the latter two printing methods is much smaller than that of offset printing. If the surface of the self-adhesive material is not smooth enough, the surface of some materials will not be printed with ink, thus forming printing white spots. This phenomenon is especially prone to occur in In the process of printing large-area dot graphics. Seen under a high magnification glass, it is characterized by the complete absence of ink in the white spot area. This is because the white point area is lower relative to other areas, and the ink on the plate is not transferred to the surface of the material. There is also an obvious feature of printing white spots caused by the surface of the material is not smooth enough, that is, the white spots are often large, and in most cases, they are all over the plate, which is very obvious.

When encountering this kind of printing white point problem, we can solve it in the following ways:

1. Replace the qualified materials. If the surface of the self-adhesive material is not smooth enough, it is a material quality problem. We can ask the material supplier to replace the material that meets the standard for production.

2. But as far as the author knows, in most cases, the replacement of materials cannot guarantee the construction period, because the production cycle of self-adhesive label printing enterprises is quite tight. Moreover, the printing factory needs a series of preparations to replace the job. Once there is a problem with the material and cannot be printed, the preparation work is done in vain, which seriously affects the production efficiency for the printing factory. If this is the case, we can consider printing a layer of primer or thinner (removal agent) on the surface of the material first. These two printing auxiliaries are basically colorless and do not affect the color of the printed matter much. After printing these two additives, the surface of the material will be filled, artificially improving the smoothness of the material, and the printing white point phenomenon will be greatly reduced.

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