The core of a TPU airtight zipper is one-piece molding: TPU pellets are injection-molded or extruded into teeth, thermally bonded with TPU tape into one unit, then joined to fabric via high-frequency welding and seamless lamination to reach IPX8 airtightness. Compared with traditional sewn + tape construction, one-piece molding eliminates needle holes and seams — the root of sealing reliability.
TPU material properties
- Elasticity, abrasion and tear resistance.
- Hydrolysis resistance: no degradation from long-term moisture exposure.
- Temperature: stable from -30°C to 70°C.
- Eco-friendly and recyclable.
Main process steps
- ① Compounding & coloring: blend TPU resin and color as required.
- ② Injection molding / extrusion of teeth into a continuous chain.
- ③ Thermal lamination with TPU tape: teeth and tape become one unit.
- ④ High-frequency welding: sliders, stops, and end structures.
- ⑤ Seamless lamination to fabric: tape covers seams, eliminating needle-hole leaks.
- ⑥ Full inspection: airtightness, cycling, tensile, and aging tests.
High-frequency welding & seamless lamination
High-frequency welding uses a high-frequency field to fuse TPU molecules themselves without glue, giving strong, invisible seams. Seamless lamination covers stitch lines with heat-seal tape to block needle-hole leakage. Together they guarantee airtight zipper reliability.
Differences from PVC / PEVA / nylon
- PVC: low cost but weaker elasticity and eco-profile.
- PEVA: lightweight but limited strength/temperature — for everyday waterproofing.
- Nylon: flexible but needs film lamination; less airtight than one-piece TPU.
Quality control
- Per-batch tests: sealing pressure, cycle life, tensile strength, thermal aging.
- Test reports available; customer spot checks welcome.