What are the techniques for heat-sealing membrane materials?

Membrane material heat-sealing technology is a critical process in the fabrication of membrane structures, primarily relying on thermal energy to melt and bond the materials. Based on the heat source and process principles, the technology is categorized into two core types:

**I. High-Frequency Welding**
**Principle:** Utilizes a high-frequency electric field (13–150 MHz) to induce internal molecular friction and heat generation in membrane materials containing polar molecules (e.g., PVC, EVA), causing them to melt; a weld seam is formed after the application of pressure and cooling.
**Key Technical Parameters:**
Power density: 5–20 kW/m²
Melting temperature: 180–220°C (e.g., for PVC)
Pressure range: 0.2–0.8 MPa
**Applicable Materials:** Polar polymer membranes such as PVC, PU, ​​and TPU.
**Advantages:**
High weld seam strength (can exceed 85% of the base material strength)
Excellent sealing performance (air permeability ≤ 0.05 m³/m²/h)
**II. Heat Sealing**
**Principle:** Achieves fusion by transferring thermal energy through direct contact between a heating plate or roller and the membrane surface, combined with the application of pressure.
**Technical Variants:**
**Type** | **Temperature Range** | **Pressure Control** | **Application Scenario**
**Flat-bed Heat Sealing** | 150–300°C | Hydraulic/Pneumatic (0.1–5 MPa) | ETFE multi-layer pneumatic cushions, waterproofing membranes