Why does aluminum-plated composite film dealuminate?

[China Aluminum Network] There are two types of dealuminization in aluminum-coated composite film packaging: flake-like black spots appear on the aluminum-plated surface, and the aluminum layer disappears. Phenomenon and Cause Analysis Flake black spots appear on the aluminized surface This is due to the fact that the vacuum metallization layer is very thin and prone to wet oxidation, resulting in the appearance of flake-like black spots on the aluminized surface of the film. Aluminized layer disappears Especially the packaging of PET aluminum film/PE film, and the edge of tuyere of PET aluminum film/PE film packaging bag. This is because the disappearance of aluminum occurs when it is damped or eroded by the adhesive solvent. This is actually a phenomenon of de-alumination. The aluminized layer of the aluminized film is damped or eroded by the adhesive solvent, and the composite film is also opened. When the internal stress of the inflated PE film shrinks and rebounds, aluminum is transferred to the inner layer film, and aluminum is lost. The support of the pellicle mirror plane disappeared as if it had disappeared. If you look closely, actually a trace amount of metallic aluminum is also concentrated on the inner film. Countermeasures 1. The sealing edge of the aluminum-plated composite bag must be pressed well. Note that the aluminum-plated surface should not be adhered to the PE film. The aluminum-plated surface should be compounded with the mask, and then the aluminum-coated film surface should be composited with the inner PE film. 2. Pay attention to the composite packaging bag of aluminum-plated film. It should not be used as a boiled and steamed bag.