When we open medicine bottles, milk powder cans, or health products in our daily lives, the layer of "sealing film" that needs to be torn off may seem simple, but it is actually a high-tech composite material. Its material design directly determines the safety and shelf life of the product. 

Core structure: Three layer composite "armor" 

The sealing film is not a single layer of plastic or aluminum foil, but a "sandwich" structure composed of precision craftsmanship: 

1. Surface layer: Support layer 

Material: Usually polyester film or special paper. 

Function: Provides mechanical strength and stability, facilitates printing of brand logos and usage instructions, and is also a substrate for composite with other materials. 

2. Intermediate layer: Barrier layer 

Material: High purity aluminum foil. This is the 'heart' of the sealing film. 

Function: Provide the most critical barrier performance. It can perfectly block light, oxygen, and water vapor, protecting the contents from moisture, oxidation, and deterioration caused by light exposure. At the same time, it is also a key component that generates heat during induction sealing. 

3. Inner layer: sealing layer 

Material: Heat sealing adhesive, usually a special polymer such as polyethylene or polypropylene. 

Function: During electromagnetic induction heating, this layer will melt and firmly adhere to the bottle mouth (plastic or glass), forming a strong airtight and water tight seal after cooling. 

Revealing the working principle: intelligent "induction heating" 

The sealing of the sealing film is not achieved by glue, but by utilizing the principle of electromagnetic induction. After the gasket is placed on the bottle mouth and the bottle cap is screwed on, the induction sealing machine on the production line generates a high-frequency electromagnetic field, and the aluminum foil layer in the middle instantly generates eddy current heating, melting the heat sealing glue at the bottom, thus achieving perfect sealing with the bottle mouth under pressure. 

Conclusion 

A small piece of sealing film embodies the wisdom of materials science and engineering. Although unremarkable, it is an indispensable "loyal guardian" that safeguards product quality and ensures consumer safety. 

Leadtra aluminum foil sealing film has introduced foreign composite equipment and technology to ensure tight and smooth sealing with easy tearing effect. It has an exquisite appearance, tight sealing, green safety, and is widely used for sealing products such as food, cosmetics, daily necessities, medical supplies, etc. If you are interested in or have any questions about us, please feel free to call us for consultation.