Except that the aluminum is usually as the main material for many aluminum products, such as the aluminum cabinet profile and the aluminum windows and doors profiles, as well as somealuminum machining parts, the aluminum can be as an assistant material product also due to its lots of good performance. One of the examples is the aluminized composite film that is used in some packaging products. The aluminized film takes the advantages of its good protection performance.
However, the aluminized composite film may be dealuminized sometimes. The dealuminization of the packaging aluminized composite film aluminum may appear in two ways:
1. There are flaky black spots on the aluminum surface;
2. The aluminized layer disappears.
1. The flaky black sports
The vacuum aluminum layer is very thin so as to make it oxidation in wet air easily. As a result, the reaction between the aluminum and the wet air produces some flaky black sports on the surface.
2. The disappearing aluminum layer
It especially happens in PET aluminum film / PE film packaging, and the outlet edge of the PET aluminum foil / PE film composite packaging bag. The reason is that the aluminum film is wetted or is eroded by the adhesive solvent in the middle part. The aluminum may have chemical reaction under these conditions and transformed into another substance.
When the aluminized layer of the aluminized film is eroded off due to the moisture or by the adhesive solution, the composite film will crack, too. When the internal stress of the inflated PE film shrinkage, the aluminum will be transferred to the inner film, and without against the outer film, the aluminum film looks like disappearing. In fact, the trace aluminum is still concentrated on the inner film.
1. When we press the sealing edge of the aluminized composite bag, pay attention that the aluminized surface should not be bonded with PE film. The aluminized layer should compound with the surface layer firstly, and then the aluminized surface film compounds with the inner PE film.
2. We have to notice that the aluminum composite film bags are not proper as boiled and cooking bags.
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