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Causes and analysis of white spots on aluminum film
Release time:
2021-11-12
In addition to the white spots on the aluminum-plated composite film, there are also obvious white spots on other composite films. These white spots can be randomly distributed and uneven in size. One type is that they appear when the machine is off, but basically disappear after aging; the other type is that they appear when the machine is off, but do not disappear after aging. The latter is a major problem that affects the performance. This type of spot is easy to appear in the printing effect of a full white background or a light yellow background. In general, as long as such white spots appear, they are generally full-page (except for equipment reasons), but the poor covering power of white and light yellow is easy to see. There are many reasons for the phenomenon of white spots, mainly three reasons:
In addition to the white spots on the aluminum-plated composite film, there are also obvious white spots on other composite films. These white spots can be randomly distributed and uneven in size. One type is that they appear when the machine is off, but basically disappear after aging; the other type is that they appear when the machine is off, but do not disappear after aging. The latter is a major problem that affects the performance. This type of spot is easy to appear in the printing effect of a full white background or a light yellow background. In general, as long as such white spots appear, they are generally full-page (except for equipment reasons), but the poor covering power of white and light yellow is easy to see. There are many reasons for the phenomenon of white spots, mainly three reasons:
1. The ink particle size is large or the particle size distribution is not wide. Generally, the particle size of white ink has a greater impact. Ethyl ester in the adhesive is a good solvent for ink. The wetting results of ink particles of different particle sizes are different. The chromaticity changes after heating and laminating or oven drying will produce differences, which looks like "white spots". In this case, it is generally obvious when the machine is off, and the white spot phenomenon will be alleviated after aging, or even disappear. When printing, it is recommended to add 1.5-3% M-27 coupling agent from Tianyang Chemical Factory to improve the compactness of the pigments and fillers in the ink system to resist large-area white spots or spots caused by solvent infiltration and destruction in the adhesive system.
2. The adhesive has high surface tension and poor wetting and spreading effect on the aluminized film. This is the current "white spot phenomenon" of aluminized film and the main reason for spots on other composite films. The coating effect of the adhesive is not good. After the printed layer is covered, the color of different parts will change, producing the same effect as before, and sometimes large spots will be produced.
3. Equipment process reasons. On the one hand, this reason is that the workers are not aware of the lamination of aluminized film. Aluminized film lamination has its place. On the other hand, the pressure on both sides of the equipment during the gluing process is inconsistent, and even the problems of the drying, coating and other systems themselves cannot fully apply the adhesive.
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