A brief description of the high-frequency welding process and performance of multi-layer co-extruded TPU calendered film

Multi-layer co-extruded TPU calendered film, combined with high-frequency welding technology, achieves a balance between material performance and processing efficiency through functional layering design and molecular-level fusion. Its products possess wear resistance, weather resistance, and environmental friendliness, making them widely used in medical, industrial, and consumer electronics fields, and an ideal alternative to traditional materials.

I. Process Flow

1. Raw Material Selection and Co-extrusion Molding

Polyester or polyether-based TPU granules are used, with the formulation adjusted according to application requirements. Polyester-based granules offer superior heat resistance and chemical corrosion resistance, making them suitable for industrial applications; polyether-based granules offer stronger low-temperature resistance and hydrolysis resistance, making them suitable for outdoor or humid environments. Multiple extruders converge TPU melts with different functions into a single die, forming a multi-layer structure (e.g., an outer wear-resistant layer, a middle reinforcement layer, and an inner sealing layer). Co-extrusion technology allows for functional layering to meet diverse needs. Molten TPU is extruded into continuous sheets through calendering rollers, resulting in high process efficiency suitable for large-scale production.

2. High-Frequency Welding Process

Utilizing high-frequency current to induce polarized friction between TPU molecular chains, instantly heating them to their melting point and achieving molecular-level fusion. This results in short welding time, a small heat-affected zone, and avoidance of material deformation. Complex shapes (such as irregularly shaped bags and three-dimensional structures) can be welded through mold design, and combined with air pressure to ensure the weld strength matches the film strength.

II. Performance Advantages

1. Excellent Physical Properties

Abrasion and Impact Resistance: TPU film combines high strength and high elasticity, resisting friction and impact for extended periods, suitable for applications such as sports footwear and automotive interiors.

Weather Stability: Wide temperature range, good flexibility at low temperatures, and resistance to softening at high temperatures; outdoor products show no aging or cracking after long-term use.

Environmentally Friendly and Biodegradable: Non-toxic when burned, biodegradable in soil, meeting environmental requirements for medical and food packaging.

2. Outstanding High-Frequency Welding Performance

Strong Sealing: Weld strength is close to that of the base material, and airtightness is superior to traditional bonding, meeting medical-grade sterilization requirements.

High efficiency and low cost: Welding speed far exceeds hot plate welding, energy consumption is low, and fully automated production is supported, significantly increasing production capacity.

Flexible design: Supports multi-layer co-extrusion of transparent and matte finishes; combined with high-frequency welding, it can create highly transparent windows or complex three-dimensional structures.

III. Application Scenarios

1. Medical Field

Bio-fluid bags: Utilizing antistatic and antibacterial co-extruded films, high-frequency welding is used to create blood bags or dialysis fluid bags, ensuring low-temperature transport resistance and reliable sealing.

Medical dressings: Ultra-thin TPU film is composited with non-woven fabric; the welded edges form a breathable and waterproof dressing, reducing the risk of clinical infection.

2. Industrial and Outdoor

Flexible storage tanks: Multi-layer co-extruded films are welded into large storage tanks, resistant to chemical corrosion, with a lifespan far exceeding that of traditional materials.

Inflatable toys: Transparent TPU films are welded into floating rafts, offering strong load-bearing capacity and being safe and non-toxic.

3. Consumer Electronics

Mobile phone cases: Co-extruded TPU films are welded into rugged shells, balancing protection and signal penetration.

Wearable devices: Ultra-thin TPU film is welded to sensors to create a breathable and comfortable smart bracelet strap.