Common aluminum plating aluminum plating CPP and aluminium coated PET, aluminum plated transfer usually appear on the aluminium coated PET, because it is often applied in the middle of composite.Aluminium coated PET, personal knowledge into two kinds: one is plating on aluminum, the second is the transfer of aluminum, the effect of two kinds of aluminum plating and adhesion are not the same.Plating up better, and transfer of the product is a lot of companies to buy PET again processing and transfer of poor, poor adhesion ability.This is because the peel strength of the film itself is too low, aluminum plating layer and base membrane between combined with poor fastness.
Normal aluminum plating film is in the bottom of the base material of vacuum aluminum plating surface with a layer of glue, used to improve the aluminized layer adhesion, and then on the bottom coating vacuum aluminum plating, coating on aluminum layer again two-component polyurethane adhesive for top coating, to protect the aluminized layer does not fall off, the aluminum plating film of aluminized layer fastness is good, not easy to fall off.And some aluminum plating film manufacturer in order to save the cost of production, in the production of aluminum plating film, not use glue, aluminum plating adhesion is low, not too strong, so it's easy to fall off.So bag factory to pay attention to the difference between when a company of choose and buy materials.
One may cause aluminized transfer factor is that opened after found plating aluminum and aluminum base material there are on either side of the above, it is obvious that this shows that the membrane has carried on the secondary aluminum plating, is for some reason of the membrane material manufacturer conducted two aluminum plating, thereby aluminized transfer happened.
Aluminized transfer there is another factor is the cause of the glue.Ordinary glue of a smaller relative molecular mass activity is strong, easy to infiltrate aluminum plating, influence aluminum plating adhesion ability, which has spread to the aluminum plating.At the same time, the solvent evaporation release ability is poorer, adhesive solution easily to infiltrate aluminized layer, destruction of aluminized layer, because of the influence of residual solvents after curing of bond strength will decline, which affect the peel strength, aluminized transfer occurs.
Now most of the manufacturers of the solution is to reduce the curing agent added.So to aluminized transfer effect of the change, but take temporary solution not effect a permanent cure, as the change of the weather, the temperature of the workshop humidity changes, it is difficult to control the amount of curing agent, which can potentially cause batch defective problem.Because most of the complex problem needs to be solid out just know how to deal with, such as curing after discovered too late.So I don't recommend this solution often used.
Glue aspect I suggest choose a moderate molecular weight, and molecular weight distribution more uniform, but also has a viscous fluid at the beginning of not too high adhesive, water-based adhesive properties can meet the requirements of the above.Water-based adhesive molecular weight of solvent adhesive is about 10 times, and molecular weight distribution more uniform and there is no aluminized layer destruction caused by the solvent permeation, thus will not affect the adhesion fastness of aluminum layer, would not be shifted aluminum plating.Water-based glue is currently on the aluminium coated packaging application is very broad, such as Shanghai long macro a two-component water-borne 268, rohm and haas of one-component waterborne 90 d has a unique advantage in this respect.To deal with the problem of aluminum plating film transfer, therefore, the selection of the adhesive is very important.
There is also a cause of aluminized transfer reason is improper operation.Operation method is not appropriate in the following aspects:
Operation, tension is too big, will lead to elastic aluminum plating film strain changes, leading to transfer;
, the gluing quantity is too large, lead to volatilize, false stem, solvent residual lead to transfer;
, residual solvent in the aluminum plating, because aluminum plating film of aluminized layer is thin, hard to avoid can have some pinhole, and residual solvents can penetrate, damage caused aluminium coated aluminum layer transfer;
Above are some of the analysis of aluminized transfer, personally think that reduce the curing agent amount this approach is not desirable, enterprises can choose reinforced aluminum plating, also can choose plating on aluminum plating to solve this problem, don't choose transfer aluminum plating and secondary aluminium coated materials.