Heat-sealable film is an important material in the packaging industry. Heat sealing technology is ideal for food packaging that requires high sealing performance. It uses heat and pressure to tightly bond different plastic films and other materials. It can be used to keep food, medicine, medical supplies, and other products intact, extend their shelf life, and maintain their freshness. This guide provides a comprehensive overview of heat-sealable film, including definitions, applicable products, and typical applications. It will help you determine whether it is the right choice for you.
What Are Heat Sealable Films?
Heat-Sealable Film is a multi-layer plastic packaging material. It can be permanently bonded under high temperature and high pressure.The outer layer has a protective layer that prevents the inner film core from melting. The inner layer material has a low melting point and melts under high temperature and pressure. The layers are bonded together using heat energy, without the need for adhesive, achieving permanent adhesion. It offers excellent sealing, leak-proof, and tamper-proof properties. It is suitable for industries with strict requirements such as food and pharmaceuticals, and also prevents contamination, ensuring product authenticity.
Heat-Sealable Film Structure
Heat-Sealable Film is designed with a multi-layer structure. Each layer has a different function, and their perfect combination gives the film excellent performance.
| Layer | Common Materials | Function |
|---|---|---|
| Outer Layer | BOPP, PET, BOPE | Provides gloss, good printability, abrasion resistance, and heat resistance during sealing. |
| Core Layer | PE, PP, BOPE | Ensures tensile strength and puncture resistance. |
| Sealant Layer | LDPE, LLDPE, EVA (Ethylene Vinyl Acetate), Surlyn (Ionomer) | Ensures bonding without damaging the outer layer, with low melting point for sealing. |
Heat-Sealable Film Manufacturing Process
Heat-sealable films are mainly made of heat-meltable plastic materials such as polyethylene and polypropylene.During heat sealing, a device similar to a sealing machine is used to heat and press two layers of plastic together to bond them. The temperature is generally between 130°C and 210°C, the pressure is between 0.25MPa and 0.55MPa, and the dwell time is approximately 0.5 to 2.5 seconds. However, the thickness, thermal conductivity, and presence of impurities in the material can affect the sealing effect. Therefore, it is necessary to ensure that the sealing surface is clean and that the machine parameters are stable and consistent.
Types of Heat-Sealable Film
There are many types of heat-sealable films, each with different characteristics to meet different packaging needs.
By Material
Polyethylene (PE) based films:
- LDPE: High flexibility and moisture resistance, suitable for packaging baked goods, frozen foods, and industrial liners.
- LLDPE: Higher tensile strength and puncture resistance, primarily used for heavy-duty packaging.
Polypropylene (PP) based films:
- BOPP: High transparency, rigidity and moisture resistance, ideal for snack foods, confectionery and baked goods.
Polyester (PET) Heat Seal Films
- Polyester heat seals: Double-sided heat-activated adhesive that can be combined with heat laminates, often used in embroidery, with good adhesion to a variety of fabric substrates.
Specialty Films:
- Disperse films (such as Surlyn): Good contamination resistance, sealing properties, oil resistance, and transparency, suitable for packaging oily or frozen foods.
- EVOH (ethylene vinyl alcohol) barrier film: Excellent oxygen barrier properties, important for products such as coffee and meat that are sensitive to oxygen during packaging.
By Structure
Monolayer Films: Usually composed of a single layer of PE or PP material, suitable for simple packaging needs such as bread bags and product packaging bags. Cost-effective and easier to recycle.
Coextruded Multilayer Films: Composed of multiple layers of different polymers, each with specific properties. Suitable for complex packaging requirements such as cooking bags and vacuum packaging. Provides enhanced barrier properties, mechanical strength, and custom features.
What Applications Are Heat Sealable Films Used For?
Heat sealing films are widely used in various fields
Food packaging:
- Modified Atmosphere Packaging (MAP): Extends the shelf life of perishable products such as fruits and vegetables by regulating the gas composition inside the package. The film is selected based on its breathability to match the respiration rate of the product, maintaining freshness and extending shelf life.
- Retort Pouches: Retort pouches are multi-layer packaging capable of withstanding high temperatures (120°C to 130°C), used for ready-to-eat foods, soups, sauces, and pet food. Made from materials such as PET, aluminum foil, and CPP, they are moisture-proof, oxygen-proof, and UV-resistant, extending shelf life without the need for refrigeration.
Pharmaceutical Industry:
- Sterile Medical Bags: These bags are critical for maintaining the sterility of medical devices and supplies. They typically feature peelable seal designs, such as a combination of Tyvek® material and transparent film, providing a breathable and antimicrobial barrier suitable for various sterilization methods.
- Blister Packaging: This is a common packaging method in the pharmaceutical industry for packaging pills and capsules. It consists of a plastic cavity made of PVC or PET and an aluminum foil cover. The aluminum foil blocks moisture, oxygen, and light to ensure the stability and effectiveness of the medication. It can also be designed to be easy to push in or child-resistant as needed.
Industrial Applications:
- Cap Liners (Bottle Cap Liners (Top Liners)): Used to seal containers and achieve leak-proof and tamper-evident closure. Induction seal liners can be bonded to the opening of the container under a heat induction process to form an air-tight seal. They are commonly used in beverage, chemical, and pharmaceutical packaging to ensure product integrity and extend shelf life.
Advantages of Heat-Sealable Film
- Improved Operational Efficiency: The heat sealing process is fast and stable, and compared to adhesive sealing, the production line speed can be increased by 30% to 50%. Production efficiency is greatly improved. Heat sealing films have good tackiness at low temperatures, which saves electricity and reduces the risk of film deformation.
- Extended shelf life: Heat-sealed films, especially those containing EVOH, have excellent oxygen barrier properties. They prevent oxygen from entering, delay oxidation, and significantly extend the shelf life of products. For example, fresh meat packaged with EVOH film has a shelf life 2-3 times longer than traditional packaging. In addition, EVOH film is transparent, allowing consumers to clearly see the quality of the product, giving them greater peace of mind and satisfaction.
- Highly sustainable:
- Recyclable: Many heat-sealing films are made of a single material, such as PE/PE or PP/PP laminates, which are fully recyclable and meet global plastic waste reduction targets. Furthermore, polyethylene resin continues to improve, and these films remain highly performant with an even wider range of applications.
- Reduced material usage: Bestypack has developed a thin heat-sealable film with a thickness of 15-20 microns, reducing plastic usage by 50%, which not only reduces environmental impact but also saves material procurement and transportation costs.
- Meets manufacturer needs: High-volume manufacturers need efficient sealing systems, and heat sealing technology is ideal. Heat sealers operate quickly, enabling fast packaging and providing stable and reliable sealing results, reducing the risk of product damage or contamination.
- Versatile: Heat sealing is suitable for a wide range of materials, and the shape, size, and pattern of the seal can be customized according to different product specifications. However, it should be noted that airtight heat sealing does not mean odor-proof. Companies that produce products with strong odors should choose the appropriate sealing type and material.
FAQ
What are the three things to consider when producing seals?
- Heat-sealable film requires heating, while cold-sealable film does not. Precise temperature control is necessary.
- The time span for which the machine jaws need to keep the sealing material together should also be considered.
- The most important factor is the pressure applied to the sealing material.
What temperature is required for heat sealing packaging?
The heat sealing temperature depends on the heat-reactive material and the thickness of the plastic.
| Polymer | Melting Point (°C/°F) |
|---|---|
| HDPE | 130°C / 266°F |
| PS | 240°C / 464°F |
| LLDPE | 123°C / 253°F |
| PP | 170°C / 338°F |
| PVC | 180°C / 356°F |
Hello, customers
My name is Jack Yu. I am the Business Manager at BestY Pack Plastic Products. My areas of expertise include film packaging, cold chain transportation packaging, and shrink products. Additionally, our factory manufactures protective gloves, and I can provide you with professional solutions to help you increase your market share and enhance consumer trust.
Email: ﾠjackyu@bestypack.com
Tel: +86 18368319351