Polyethylene terephthalate (PET) films are versatile packaging materials known for their excellent combination of properties. They are transparent and glossy, with good gas barrier and aroma retention capabilities. PET films have moderate moisture resistance, which improves at low temperatures. Mechanically, PET films are exceptionally strong and tough, outperforming most other thermoplastics in tensile and impact strength. They also maintain their shape well, making them suitable for printing and secondary processing like bag making. PET films are highly heat and cold resistant, and they have good chemical and oil resistance. However, they are not resistant to strong alkalis and are prone to static electricity, which can be problematic when packaging powdery materials.
Types of PET Films
1. PET High Gloss Film
Properties: In addition to the excellent physical and mechanical properties of regular polyester films, PET high gloss films have exceptional optical properties.
Applications: Used in high-end vacuum metallization products, where the film achieves a mirror-like finish after metallization, providing an attractive packaging and decorative effect. It is also used in laser holographic anti-counterfeiting base films.
2. PET Transfer Film
Properties: High tensile strength, good thermal stability, low thermal shrinkage, smooth and clean surface, and good peelability. It can be reused multiple times.
Applications: Mainly used as a carrier for vacuum metallization. The process involves metallizing the PET film with aluminum, laminating it with paper using adhesive, and then stripping off the PET film to transfer the aluminum layer onto the paperboard, creating metallized cardboard. This metallized cardboard is used in packaging for its metallic appearance and recyclability.
3. PET Reflective Film
Properties: Excellent optical properties, smooth and clean surface, good thermal stability, low shrinkage rate, and resistance to photodegradation.
Applications: Widely used in traffic facilities, such as reflective road signs, reflective isolation tapes, reflective license plates, reflective vests, and industrial safety signs. Reflective films are made by coating PET films with aluminum and attaching glass microbeads with high refractive indices (1.9) to enhance reflectivity.
4. PET Chemically Coated Film
Properties: Improved surface properties for better printability and adhesion of vacuum metallized layers. Chemical coating overcomes the limitations of corona treatment, which can degrade over time, especially in humid conditions.
Applications: Used in printing and metallization industries to enhance surface tension, improve printability (using water-based inks), and strengthen the bond between the metallized layer and the PET base film. It can also be used to produce high-barrier and antistatic films.
5. PET Antistatic Film
Properties: Contains antistatic agents that form a thin conductive layer on the surface, reducing static buildup and improving surface conductivity. The surface resistivity is typically ≤10^9 to 10^11 ohms.
Applications: Essential for packaging sensitive electronic components, circuit boards, and communication devices to prevent electrostatic discharge (ESD) damage. Also used in industries where static electricity can cause safety hazards.
6. PET Heat Sealable Film
Properties: Modified PET resin with a three-layer structure (A/B/C) allows for heat sealing without deformation or shrinkage.
Applications: Used for packaging various products and as a protective film. It eliminates the need for laminating PET films with other materials like PE or CPP, expanding the application range of PET films.
7. PET Heat Shrinkable Film
Properties: A novel heat shrinkable packaging material with excellent recyclability, non-toxicity, and odorlessness. Modified PET films can achieve high shrink rates (up to 70%) and are stable at room temperature, shrinking significantly when heated above the glass transition temperature.
Applications: An eco-friendly alternative to PVC shrink films, used for packaging products that require a tight, conforming wrap.
Characteristics of PET Protective Films
- Excellent Transparency and Gloss: Provides a high-quality visual appearance.
- Non-toxic and Hygienic: Safe for food and pharmaceutical packaging.
- Good Thermoforming Performance: Comparable to PVC, suitable for vacuum forming to create high-quality PET thermoformed products.
- Superior Surface Decorative Properties: Can be printed without surface treatment, easily embossed with patterns, and metallized (vacuum coated with metal layers).
- Low Surface Resistance: Achieved by coating with conductive polymers, ensuring stable performance regardless of environmental conditions.
- High Mechanical Strength: Resistant to tearing and puncturing.
- Good Chemical Resistance: Withstands exposure to various chemicals.
- Environmentally Friendly: Recyclable and does not produce harmful by-products when incinerated.
- Good Barrier Properties: Effective against oxygen and moisture, protecting packaged goods from spoilage.
