Aluminum foil is the only kind of metal foil in composite packaging materials.
As a metal material, aluminum foil has incomparable water resistance, gas resistance, light shielding and taste retention.
Aluminum foil is made of electrolytic aluminum with purity of 99.0% ~ 99.97% and rolled for many times.
It is rich in resources and has considerable advantages in cost performance.
Characteristics of aluminum foil
1. Aluminum foil has shiny metallic luster and strong decoration.
2. Aluminum foil is non-toxic, tasteless and odorless. It is suitable for all kinds of food and drug packaging
3. Relatively light weight, the specific gravity is only one-third of that of iron and copper, rich in extensibility, thin thickness and small unit area.
4. It has good shading, and the reflective rate can reach 95%. It is commonly used as reflective materials.
5. Strong protection, so that the packaging is not vulnerable to bacteria, fungi and insects.
6. High temperature and low temperature are stable, and the temperature is – 73 ~ 371° No expansion and contraction deformation at C.
7. Excellent barrier, moisture-proof, air tight and fragrance preserving, which can prevent moisture absorption, oxidation, volatilization and deterioration of packaging contents.
8. Aluminum foil is easy to process and can be compounded with various plastic films and paper.
9. The disadvantage of aluminum foil is that it has low strength and is easy to tear, so it can not be used for packaging products alone.
Quality requirements for aluminum foil
The surface of aluminum foil shall be clean, bright, flat and free of crack and indentation. No corrosion trace, rough surface left by burning oil, no lubricating oil trace and spot, no kerosene smell.
2. Degreasing degree
The oil stain grade of aluminum foil for composite packaging materials shall be grade a-b.
Due to the influence of rolling process, rolling oil, rolling roll and production environment, aluminum foil will inevitably have pinholes and other defects.
Therefore, the barrier of aluminum foil in composite packaging materials depends on the size and quantity of pinholes.
In gb3198-1996, the size and quantity of pinholes in aluminum foil are specified accordingly.
Among them, the diameter of medicinal aluminum foil pinholes shall not be greater than 0.3mm, and shall not exceed 5 / ㎡.