Many customers in the frozen food industry have asked this question: if you put sealing film in a freezer, will it become brittle, crack, or fail to seal?

The answer is: Yes, it can be used — but not every sealing film is suitable. The key is low-temperature performance.

How frozen foods challenge sealing film

Frozen foods are typically stored at temperatures between -18°C and -40°C, sometimes even lower. At such temperatures, ordinary sealing film may encounter two problems. First, becoming brittle — the film loses flexibility in low temperatures and cracks under minimal stress. Second, heat-seal layer failure — low temperatures cause the heat-seal layer to harden, reducing adhesion to the bottle mouth and compromising the seal.

Some composite films on the market have a temperature range rated from -40°C to +220°C, indicating they maintain stable performance in both freezing and high-heat environments. These films typically use a PET/PE composite structure, where the PE layer provides low-temperature toughness and the PET layer provides structural support.

How to evaluate a sealing film's low-temperature performance?

Look at the material. A sealing film's low-temperature performance mainly depends on its heat-seal layer material. PE (polyethylene) has a brittleness temperature typically below -70°C, making it the most common choice for frozen packaging. If the film contains EVOH or aluminum foil, these layers maintain barrier properties even at low temperatures. Some sealing films designed for frozen food packaging maintain stable sealing performance across a wide temperature range from -40°C to +220°C.

Check for test standards. China already has a specific group standard for low-temperature tolerance in frozen food packaging (T/HNSPGYXH 024-2024). This standard applies to packaging films and bags made from various plastic materials or aluminum foil composites, with service temperatures ranging from 0°C down to -120°C. If a supplier can provide a test report compliant with this standard, the product has passed low-temperature performance verification.

Run a freezer test. The most straightforward method: seal the film onto bottles, place them in a -18°C freezer for 48 hours, then check for cracks, seal integrity, and whether the film remains flexible after returning to room temperature.

What does a good sealing film for frozen foods look like?

An ideal sealing film for frozen applications typically has several characteristics: a heat-seal layer made of PE or modified PE with a brittleness temperature below -60°C; high interlayer adhesion strength to prevent delamination at low temperatures; and if it contains aluminum foil, low pinhole density to prevent moisture vapor penetration during freezing.

If you're unsure whether your existing sealing film can withstand freezing conditions, send a few sealed samples to Leadtra Packaging. We can run low-temperature tests for you — to see whether the film still holds up after being frozen at -18°C.