The processing method of aluminizing film is to vaporize metal aluminum under high vacuum condition and make aluminum vapor precipitate on the surface of plastic film to form a kind of composite soft packaging material in soft plastic packaging. The aluminized films often used are basically divided into two categories: CPP aluminizing and pet aluminizing. However, the aluminizing transfer phenomenon is easy to occur after the aluminum coating is recombined, which brings great losses to many packaging enterprises. In this paper, different solutions are put forward from the angle of binder to prevent the transfer of aluminized film.
1, two-component polyurethane adhesive
1) A special adhesive for aluminum plating is used. The solvent release property of ordinary adhesive is poor, and the binder can easily penetrate into the aluminized layer, which affects the fastness of the aluminized layer, and if the drying effect is not good when the composite is made. If the solvent residue is too large, the bond strength will decrease after curing, even the phenomenon of aluminizing transfer will occur. Therefore, the molecular weight should be chosen to be moderate, and the solvent release ability should be good. The uniform initial adhesion is not high.
2) the appropriate amount of glue coating is large, which can easily lead to poor drying effect of oven, which makes the adhesive permeate into the aluminized layer, and also prolong the curing time. It is easy to transfer the aluminized layer. Therefore, the amount of coating should be controlled in the appropriate position and generally controlled at 22.5 g according to the experience.
3) reducing the amount of curing agent to improve the softness of the rubber layer can also effectively prevent the transfer of the aluminized layer. In the past, reducing the amount of curing agent is usually used, which can only be used in products with light packaging and low peeling strength. Polyester aluminum plating products as far as possible do not use this method.
4) increase drying temperature and wind speed in the process of aluminum film composite processing, should appropriately increase the drying temperature of the oven, such as raising 5-10 degrees. And to ensure that the wind speed of more than 5 m / s, so that the solvent volatilization more thoroughly, reduce solvent residue, but also can use high mesh wire, high concentration coating can also.
5) to raise the curing temperature. In the process of curing, the curing temperature should be raised properly and the curing time should be shortened so that the adhesive can reduce the permeation and destruction of the aluminized coating and effectively prevent the transfer of the aluminized coating. General control temperature 50-60 degrees, time around 24 hours, do not cure for a long time.
6) the use of quality aluminum film such as cost allowed, should buy high quality aluminum film, such as bottom coating.
2, waterborne binder
1) for the packaging of light products, such as expanded food, instant noodles and other production, the basic material used for cpp aluminum plating, in order to control production costs. Most of the use of one-component water-based binder, in the production process for many years, only the problem of ink transfer, but not aluminized transfer, at the same time through actual testing. The peeling strength can be more than 1.on / 15mm, which can meet the standard requirement of this kind of packaging products.
2) using waterborne adhesive to produce aluminum plated products, and using about 200 lines for wire roller. The amount of glue added is controlled at 1.2g, which ensures uniform coating amount and good drying effect, which not only reduces the production cost to a certain extent, but also effectively solves the problem of solvent residue. To ensure the normal production of customers. Reduce the adverse effects of residual solvent if the standard. At the same time, the full version of white ink products, the effect is particularly ideal.
Methods and Countermeasures of preventing transfer of Aluminium plating Film
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