In retort packaging bags, the aluminum foil used is mostly soft aluminum foil with a thickness of 9 μm (7 μm thickness can also be used). It has excellent moisture barrier, gas barrier and light barrier properties. Therefore, composite packaging bags containing aluminum foil are Fully sealed, high fragrance retention, high oil resistance, high temperature resistance and other properties are very popular among users.
The surface cleanliness of the aluminum foil should be high, free of oil and dust, and the surface tension should be high, which should be above 72mN/m. A simple method is to use distilled water to test. The distilled water should completely wet the surface of the aluminum foil. If the surface of the aluminum foil is seriously oily, it will affect the composite fastness of the aluminum foil and other materials. Especially after the packaging bag is cooked at high temperature, delamination will occur.
The texture of aluminum foil should be soft, not easy to break when folded, and should have good toughness. The purchased aluminum foil should be stored in a dry state and should not be left for too long. It should be used as soon as possible to prevent the aluminum foil from absorbing moisture and oxidizing and deteriorating.
