One, dry compound definition
Apply liquid adhesive to a layer of film (first substrate), evaporate the solvent in the adhesive through an oven to a solid "dry" state, and heat with another layer of film (second substrate) The process of pressing the composite film.
2. Dry compound process
3. Attention should be paid to the production of dry composite membranes
1. Pay more attention to the amount of glue
There are two different gluing methods in the current dry laminating machine compound gluing system:
The first gluing method is reverse roll gluing. This method is generally applied to domestic small low-medium speed dry laminating machines. The gluing amount control depends on the pressure control of the pressure control roller and the adjustment of the glue solubility. When the start-up speed is relatively fast, it is easy to cause the phenomenon of falling glue and flowing glue, and uneven coating.
Another method of gluing is anilox roller gluing. Most of the current medium and high speed dry laminating machines are coated with anilox rollers. The gluing amount control depends on the adjustment of the solubility of the glue solution and the selection and control of the anilox roller. Roller pressure adjustment, blade angle adjustment. The method has high production efficiency, uniform coating and good quality of composite products.
2. Pay more attention to the selection of the anilox roller
In the production of dry composite film, anilox roll gluing generally needs to be equipped with three sets of anilox rolls, 70 lines- 80 lines are used to produce high-glue cooking and packaging products; 100 lines- 120 lines are used for boiling Packaging of medium-resistant products; 140-160 is used to produce light-weight packaging products with less glue.
In the anilox roll gluing system, the scraper should be checked frequently, keeping the blade straight, and checking the angle between the knife holder and the anilox roll. The blade pressure is generally 3-5kg (up and down according to the actual situation), the tangent of the blade and the coating roller is about 60 °, the blade is exposed to the blade pressure plate 5mm during installation, and the blade direction is upward. The anilox roller should be kept clean and free of blockage. In addition, the pressure on both sides of the rubberized rubber pressure roller should be even, the surface of the rubber roller should be inspected for damage and defects, and whether it is soft or hard. The leveling roller must be smooth and flat, and do not leave dirt, which is related to the flatness of the composite film and the uniformity of the glue.
3. Pay attention to the environmental impact
The dust in the air will adhere to the film and affect the adhesion. Especially at the air supply port of the oven, the strong air flow will sandwich the dust particles and sprinkle the film. Therefore, the environment should be kept clean and hygienic and the filter screen at the air outlet should be cleaned frequently. Eliminate static electricity on the film and pay attention to keeping the machine environment sanitary. The adhesive solvent is completely sealed and stored and filtered in use. In addition, in order to prevent dust from adhering to the composite surface of the film, it is necessary to clean the anilox roller and the film, clean the composite roller, and pay attention to environmental hygiene. The temperature of the working environment is also very important. The temperature should be 21-25 degrees, the humidity should be 65% , the humidity is too high, the adhesive and the substrate are easy to absorb moisture, and quality accidents occur.
4. Pay attention to curing time and temperature
If the aging time is insufficient, and there are too many residual solvents, bubbles will be generated, delamination or corners of the bag will curl. If the curing temperature is too high, the dry composite film will curl. Different types of adhesives require different curing times. For example , curing agents made with aliphatic IPDI (isophorone diisocyanate) and curing agents made with aromatic TDI (tetraphenyl diisocyanate), Due to the weak reaction ability of IPDI with hydroxyl group ( -OH ), it is necessary to use a catalyst (in the production of glue) and increase the curing time. In addition, low ripening temperature will also cause insufficient ripening.
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