1、 "Spots or bubbles" produced by aluminum coated composite products
Spot phenomenon was observed on site
（1） If the ink layer of the composite product is different in depth and color, or there are ink marks on the web roller, the composite product will have gray white spots immediately after the machine is finished, but this phenomenon has been reduced or eliminated after aging.
Phenomenon analysis:
1. After the printing film is compounded, the peeling strength between the composite layers will be different, and the covering power of the ink itself is poor. Through the reflection of the aluminum coating, the "spot" phenomenon will be formed, which will not be eliminated.
2. The plastic (titanium dioxide) and resin in the ink are soaked by the ethyl ester in the adhesive, that is, the ink layer is dissolved by the ethyl ester in the adhesive, so it looks gray and white spots, but after aging, this phenomenon will be reduced.
3. The viscosity of the adhesive used in lamination is too high, and it is easy to pull the printing ink to the web roller and the rubber plate, resulting in the different depth of the printing layer, and the so-called "spot" phenomenon is formed through the reflection of the aluminum coating.
terms of settlement:
1. The above two reasons often exist at the same time, so we should consider each other when solving them. Using ink with good covering power is the most fundamental solution to eliminate the spot phenomenon caused by it.
2. The amount of residual solvent can be reduced by increasing the temperature and air volume of drying channel. At the same time, for the composite of pet aluminum coating, we can use the pet aluminum coating glue to isolate the influence of ethyl ester solvent on the ink.
3. As for the third case, if vm-pet is involved in the lamination, it can be reversed, that is, using PET aluminum coating to glue. In addition, the key is to master the viscosity of adhesive, first of all, to reduce the concentration of adhesive, viscosity. It is better to use high solid content and low viscosity adhesive, and use shallow anilox roller to glue under high concentration and low viscosity conditions.
（2） When the compound product has spots, it will stop to observe after the printing film is glued, and the glue layer will shrink. The spots generated by this phenomenon will not be reduced or eliminated after aging.
Analysis and solutions:
1. The surface tension of printing layer is low by using surface modified ink, which leads to shrinkage of adhesive on its surface.
2. Adhesive itself coating performance is poor, or the concentration is too high, resulting in adhesive performance tension is too high. When compounding, the printing film shrinks.
3. After the adhesive is prepared, the storage time is too long, and the indoor temperature and humidity are high, which makes the adhesive viscosity rise after preparation, which affects the coating performance.
4. Impurities such as water with high surface tension were mixed into ethyl acetate. The results show that the coating performance becomes worse after compounding, and the longer the time is, the more obvious the effect is.
（3） The "spot" of the composite product will not shrink after the printing film is glued, and the "spot" will not be reduced or eliminated after aging. Through interlaminar peeling, there is a significant difference in peel strength between the "spot" and the "spot".
Phenomenon analysis:
1. After the composite product is off the machine, the "spot" phenomenon will appear. First, cut a small piece of composite film and put it into the oven for more than ten minutes to observe whether the "spot" phenomenon disappears. Such as "spot" phenomenon does not disappear or basically unchanged.
2. Because there is a significant difference in the peel strength between the "spot" and the "spot", the adhesion between the ink house and the coating is low at the spot generation place; the aluminum coating has been obviously transferred in the place without spots, and the tightness between the layers is good. Through the aluminum coating reflection strength, the formation of white or gray spots. Its spot depth and ink coverage has a great relationship. In contrast, the spots are serious.
3. On site inspection of the quality of aluminum coating, whether the required surface tension.
4. Check whether the glue amount meets the requirements, and check the wire roller if necessary.
5. Whether it is caused by net wall gap. This point can be judged as long as the spots of composite products are amplified and analyzed.
6. Judge whether the spot phenomenon caused by adhesive. If the adhesive has poor affinity to aluminum coating, especially OPP printing film and OPP printing film combined with aluminum coating, the adhesive performance is more obvious. Due to the influence of residual solvent, the strength of the adhesive is not as good as the initial adhesion. When this kind of adhesive is used on the wire roller above 150 lines at high speed, the phenomenon of white spot is more obvious.
terms of settlement:
1. Aluminum coating with good quality was used to composite.
2. The amount of residual solvent can be reduced by increasing the temperature and air volume of drying channel.
3. Install cots on the equipment.

4. Some spot phenomenon can also be solved by using proper adhesive for aluminizing film. This adhesive has moderate and uniform molecular weight and relatively high initial adhesion, but it has excellent coating performance and good solvent release. The peel strength is good after aging.

5. In addition, if there is no better adhesive for aluminizing film, deep wire roller can be used, and the operation concentration can be reduced and the machine speed can be slowed down to reduce or solve the "spot" phenomenon.
2、 Cause analysis of "spot or bubble" in transparent composite film
The appearance of "spots or bubbles" in the transparent composite film not only affects the appearance quality, but also affects the peel strength of the composite film.
The performance of compound
1. Compound products have "spots or bubbles" before aging, but they can be reduced or eliminated after aging.
2. Check whether there are other crystal points or impurities in the "spot or bubble" of the composite film. This is very important.
3. Check that the shape of the spots or bubbles is regular.
4. There is no "spot or bubble" before aging, but there is "spot or bubble" after aging
5. There are "spots or bubbles" where there is printing ink, and there is no bubble in the blank.
6. Full version with lots of "spots or bubbles"
7. Phenomenon analysis and solutions:
（1） The first phenomenon is normal after ripening.
(2)
1. Environmental factors such as: dust and impurities, then do a good job in environmental hygiene. In addition, there are impurities in the glue solution, which are filtered.
2. The prepared glue was mixed with water and was not dried at the temperature of 60-90 ℃. It reacted with curing agent to produce carbon dioxide bubble and white crystal point after crosslinking. At the same time, the composite membrane also contains air bubbles and water bubbles.
3. The humidity in the working environment is too high, and the moisture in the air adheres to the plastic surface, especially the plastic film with high moisture absorption, such as nylon, cellophane, etc., is easy to crystallize.
（3） The results show that the concentration of adhesive is too thin, resulting in insufficient amount of glue; the selection of web roller is relatively shallow, resulting in insufficient amount of glue; web roller blocking causes regular "spots or bubbles" phenomenon.
(4)
1. Due to the influence of residual solvents, the oven temperature should be increased properly.
2. Due to the lack of the initial adhesion force, the adhesive with higher initial adhesion force can be replaced or the temperature of the heat sealing roller can be appropriately increased.
3. The difference of film surface tension will also cause the lack of initial adhesion.
(5)
1. Printing ink and adhesive do not match. Cause printing ink and adhesive poor adhesion.
2. The printing ink layer appears false dry phenomenon, after compounding, the residual solvent erodes the printing and composite layer.
(6)
1. Poor film quality means that the surface tension of the base film is too poor, resulting in poor leveling of adhesive or bubbles in the place without adhesive
2. When compounding, the angle of scraper and the drop of glue liquid are large, and bubbles are produced by impact. When the laminating machine is running at high speed, bubbles can not be dissipated in time, and a large number of bubbles are generated in the glue tray, and then they are entrained into the film and transferred to the film.
3. Due to the insufficient compound pressure, the surface temperature of the composite roller is too low, the activation of adhesive is insufficient, and the fluidity is small, so that the gap between the glue liquid dot and the dot can not be filled, resulting in a small gap, resulting in bubbles.
4. Adhesive quality problems.
5. The influence of water and alcohol should be avoided when compounding.
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.
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