Analysis of the Welding Principle, Process and Application of TPU Film Heat sealing (hot press plate)

I. Welding Principle

The heat-sealing welding of TPU (thermoplastic polyurethane) films is based on their thermoplastic properties: heating via a hot press melts the film's contact surfaces, causing molecular chains to diffuse under pressure and form strong molecular bonds upon cooling. This process requires no adhesives, relying on the material's own melting and re-solidification to achieve a seal.

II. Core Processes

1. Temperature Control: The heating temperature needs to be adjusted according to the TPU formulation (usually below the decomposition temperature) to ensure uniform melting.

2. Pressure and Time: Apply appropriate pressure (to avoid film deformation or inadequate sealing), combined with short heating times (to prevent overheating and degradation).

3. Cooling and Curing: Maintain pressure cooling after welding to ensure full curing of the molecular chains and improve weld strength.

4. Optimization Directions: Double-sided heating to shorten time, pulse control to avoid localized overheating, and mold design to reduce stress concentration.

III. Typical Applications

1. Medical Field: Aseptic packaging (e.g., surgical gowns, plasma bags), medical catheter connections (requires biocompatibility certification).

2. Consumer Electronics: Sealing for smart wearable devices (e.g., waterproof watch straps), flexible battery encapsulation.

3. Automotive Industry: Interior sealing (e.g., seat airbag covers), fuel line connections (oil resistance required).

4. Packaging Industry: Food composite film sealing (e.g., TPU/PET), welding of chemical container linings.