Lidding Films

The Main Functions and Core Requirements of Lidding Film

The Lidding Film is not merely a simple covering material. Lidding film needs to meet a series of complex and stringent requirements:

1. Outstanding sealing performance:

• Lidding film must form a firm and tight heat seal with the container (usually made of PP, PS, PET, APET/PP trays, etc.).

• Ensure that the contents do not leak, do not lose moisture, and prevent the invasion of external oxygen, moisture, and bacteria, thereby maintaining the freshness and safety of the product within the shelf life.

2. Convenient opening:

• This is one of the most crucial characteristics of Lidding Film. It must enable consumers to open the lidding film easily and safely without the need for tools or excessive force.

• The opening force needs to achieve a perfect balance between "firm sealing" and "easy opening". This is usually demonstrated through the lidding film's easy-tearability and peelability.

3. High barrier properties:

• According to product requirements, Lidding Film needs to provide varying degrees of barrier properties against oxygen, water vapor, odors, light, etc.

• For example, snacks and meat products that are sensitive to oxygen require high oxygen-blocking film.

4. Excellent physical strength:

• The lidding film should have good resistance to puncturing, tearing, and explosion, to withstand the compression and impact during transportation and stacking, and prevent the contents (such as sharp snacks) from puncturing the packaging.

5. Safety and compliance:

• The parts in direct contact with food must comply with relevant food safety regulations (such as China's GB 4806, EU's EU 10/2011, etc.), without causing harmful substance migration.

6. Excellent printing adaptability:

• The outer surface needs to be capable of high-quality, high-resolution printing to carry brand logos, product information, usage instructions, etc., to attract consumers and convey information.

Typical Structure and Materials of Lidding Film

Lidding Film is usually a multilayer co-extruded or dry-film laminated composite film. Each layer has its specific function. A typical high-performance lid film structure is as follows:

Outer Layer / Printing Layer:

• Materials: BOPET (polyester), BOPP (polypropylene), NY (nylon), etc.

• Function: Provides excellent printing surface, wear resistance, and gives the film stiffness, facilitating stable operation on high-speed packaging machines.

Middle Layer / Barrier Layer:

• Materials: Aluminum foil, aluminum-coated film, EVOH, PVDC, etc.

• Function: Provides the core barrier properties (oxygen barrier, moisture barrier, light protection). Aluminum foil offers nearly absolute barrier.

Inner Layer / Heat Sealing Layer:

• Materials: CPP (extruded polypropylene), LDPE (low-density polyethylene), modified PE (such as Surlyn), etc.

• Function: This is the key layer in direct contact with the container and for heat sealing. Its formulation determines the heat sealing strength, opening force, content resistance (such as oil resistance, acid resistance), etc. Through special material modification, an easy-peeling effect can be achieved.