Heat Sealable PET Film: Structure, Technology, Benefits & Applications
What is Heat Sealable PET Film?
Heat Sealable PET Film is a high-performance biaxially oriented polyester film (BOPET) engineered with a special heat sealable layer that enables direct sealing under heat and pressure without the need for adhesives.
By combining the strength and thermal stability of PET with low-temperature sealing capability, this film is widely used in food packaging, beverage containers, and lidding applications.
Origin of Heat Sealable PET Film Technology
Heat sealing technology originated with the development of thermoplastic polymers such as PET in the mid-20th century. As packaging industries evolved, traditional sealing methods (adhesives or mechanical sealing) were gradually replaced by thermal sealing systems.
With advancements in:
Co-extrusion technology
Multi-layer film design
High-speed packaging equipment
Heat sealable PET film has become a key material in modern packaging, especially for food safety and high-efficiency production.
Manufacturing Process of Heat Sealable PET Film
The production of heat sealable PET film is similar to standard BOPET film but includes multi-layer co-extrusion technology.
Main Process Steps:
Melt extrusion (single-layer or multi-layer co-extrusion)
Casting (sheet formation)
Longitudinal stretching (MD orientation)
Transverse stretching (TD orientation)
Heat setting
Winding and slitting
This process ensures:
High mechanical strength
Excellent dimensional stability
Superior thermal performance
Structure of Heat Sealable PET Film (A/B/C Design)
Heat sealable PET film is typically produced as a three-layer co-extruded structure (A/B/C structure):
A Layer – Heat Seal Layer
Made from amorphous copolyester
Acts as the heat sealable surface
Thickness: 10%–20% of total film thickness
Enables sealing at lower temperatures
B Layer – Core Layer
Biaxially oriented PET (BOPET)
Provides:
Strength
Rigidity
Heat resistance
C Layer – Back Surface
Usually corona treated
Ensures:
Excellent printability
Good ink adhesion
Heat Seal Strength
Typical range: 5 – 8 N / 15 mm
Can be adjusted based on application requirements
Heat Sealing Principle
Heat sealing works through thermal activation of the seal layer:
The heat seal layer softens or melts at a specific temperature
Pressure brings surfaces into close contact
Cooling solidifies the bond
Result:
A strong, uniform, and leak-proof seal formed by molecular bonding.
Why Use Heat Sealable PET Film?
✔ Reliable Sealing Performance
Strong and consistent seals
Excellent leak-proof capability
✔ High Temperature Resistance
Suitable for freezer-to-oven applications
Ideal for ready meals
✔ No Adhesives Required
Cleaner process
Safer for food packaging
✔ High Processing Efficiency
Compatible with high-speed automatic packaging lines