The welding temperature range of PVC/PVDF coated fabric

The welding temperatures for PVC and PVDF coated fabrics differ significantly due to their distinct material properties:

• PVC: Typically 120°C–240°C
• PVDF: Strictly controlled within 180°C–230°C

Below is a detailed analysis:

I. Welding Temperature Range for PVC Coated Fabrics

1. Material Characteristics

• PVC (polyvinyl chloride) has a narrow window between its melting and decomposition temperatures.
• Softening point: 65°C–85°C
• Decomposition initiates at 140°C, with full molten state achieved above 170°C.
• At 180°C, decomposition accelerates, releasing hydrogen chloride (HCl) gas that corrodes equipment and weakens welds.

2. Recommended Welding Temperatures

• High-frequency welding: 180°C–240°C (common for membrane structures, inflatable products).
• Hot air welding:
  • 150°C–170°C for soft PVC films.
  • 180°C–220°C for rigid PVC films.
• Ambient temperature: Maintain workshop temperature at 10°C–25°C to stabilize material behavior.

3. Key Temperature Control Guidelines

• Low temperatures cause weak bonds and cracking; excessive heat accelerates decomposition.
• Adjust temperature based on material thickness and plasticizer content (e.g., lower temperatures for soft PVC with high plasticizer content).

II. Welding Temperature Range for PVDF Coated Fabrics

1. Material Characteristics

• PVDF (polyvinylidene fluoride) is a high-performance fluoropolymer with a higher melting point (160°C–180°C) and hygroscopicity.
• Long-term service range: -60°C–150°C; short-term tolerance up to 170°C.
• Decomposition (>250°C) releases toxic hydrogen fluoride (HF).

2. Recommended Welding Temperatures

• Hot air welding:
  • Gun temperature: 300°C–350°C, but ensure material surface temperature does not exceed 230°C.
• Hot plate welding:
  • Plate temperature: 210°C–230°C (slightly above melting point).
  • Maintain intact PTFE coating on heating plates to prevent material sticking.
• Pre-drying: Dry in an oven at 80°C–100°C for 2–4 hours (depending on thickness) to remove moisture.

3. Key Temperature Control Guidelines

• Low temperatures result in incomplete fusion and weak seams; overheating causes decomposition, leading to bubbling or discoloration (yellow/brown).
• Adjust parameters based on welding method:
  • Hot plate welding requires precise plate temperature control.
  • Hot air welding relies on airflow speed and welding speed to regulate material temperature.