There are also two phenomena in the appearance of spots
One is that there is no spot when the composite is off the machine, and the spot appears after aging;
Second, there are spots after the compound machine. If it appears regularly and regularly, the film leveling state, mechanical parallel state, whether the hot pressing roller has pollution, whether there are scars, and whether the rubber roller system has defects) should be considered.
Phenomenon 1: there is no spot after getting off the machine, and the spot appears after aging.
Causes:
1. The white oil ink is too rough, and the particle size of titanium dioxide in the ink is large.
2. The proportion of adhesive in the ink is small, resulting in pores in the ink layer.
3. The coating amount of adhesive is too small. In the aging process, due to the attraction between molecules, capillary phenomenon and other reasons, the adhesive crawls into the micro pores of the ink, resulting in the loss of adhesive on the interface and forming a cavity, which is white spot from the surface.
terms of settlement:
1. Change the ink;
2. Increase the amount of adhesive coating.
Phenomenon 2: there are spots after getting off the aircraft.
Causes:
1. The adhesive has high cohesion and poor fluidity, which results in poor leveling. There is no adhesive on some interfaces. Coating is too small, can not reach the flow of the necessary conditions.
Solution: change the adhesive or change the working solution concentration of coating; increase the coating amount.
2. The ink interface is rough, and the flow resistance of adhesive is increased, resulting in some interfaces without adhesive and without bonding.
Solution: increase the amount of coating, appropriate use of high concentration or change ink.
3. The drying effect of the first stage is too high, the solvent in the adhesive volatilizes too fast, and the surface tension of the adhesive layer increases too fast, resulting in poor leveling performance, which makes some interfaces have no adhesive bonding.
Solution: adjust the composite process to reduce the temperature of the first section of air volume.
4. The binding force of the adhesive to ethyl ester is low, and the drying speed is fast in the first drying channel, which makes the surface tension of the adhesive layer rise too fast, and the leveling property is reduced, resulting in no adhesive and no bonding at some interfaces.
Solution: adjust the composite process to reduce the temperature of the first section of air volume.
5. Due to the blocking of wire roller, the coating amount of adhesive is reduced, and the necessary leveling amount is reduced, so that there is no adhesive on some interfaces.
Solution: use washing solution to clean the wire roller.
6. The wire roller does not match with the use concentration, and the mesh wall is too wide, resulting in insufficient coating amount or too large flow distance of adhesive after coating, which can not meet the leveling requirements, resulting in no adhesive and no bonding at the interface.
Solution: replace the mesh roller, make it match with the adhesive working fluid concentration or adjust the working fluid concentration.
7. If the humidity is too high, due to the evaporation of ethyl ester, the heat will be taken away by the volatilization of ethyl ester, the water will condense into the glue liquid, or the cloth surface, or the solvent will have too much moisture. The above two reasons lead to the change of glue system.
Solution: heat adhesive in plum rain season. The rubber tank is equipped with jacket, and the jacket is filled with hot water (3-5 ℃ above room temperature)
8. The surface tension of the film is small, resulting in the mismatch between the surface tension of the adhesive itself and the film tension, and the adhesive is not easy to flatten.
Solution: treat the substrate.
The above reasons for the formation of spots are basically interactive, and it is unscientific to judge the absolute causes alone. The problem may be solved by changing the adhesive varieties (different manufacturers) in the same process. And the same adhesive change the use of process conditions, the problem may also be solved. Therefore, we should not rush to a conclusion on the problem of leukoplakia.
Dongguan Beite packaging materials Co., Ltd. - located in Dongguan City, the world's manufacturing city, is a subsidiary of Beite packaging (China) Co., Ltd., with a plant area of 6000 square meters. It is a flexible packaging enterprise integrating R & D, production and sales. It has a complete set of domestic advanced production equipment, a scientific and humanized management system and a group of experienced technical personnel For backing, to provide customers with quality products and first-class service.
The company produces composite bags, roll film, fruit bags, aluminum foil bags, suction mouth bags, self-supporting bags, zipper bags, anti-static bags, special-shaped bags, etc., which are suitable for the internal and external packaging of food, daily chemicals, electronics, toys, medicine, cosmetics, industrial products and other industries.
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