Analysis of the Principle and Core Applications of High-frequency Welding for Nutrition Bags

I. High-Frequency Welding Principles: Molecular-Level Heating and Seamless Fusion

High-frequency welding (also known as dielectric welding or radio frequency welding) utilizes a high-frequency electric field (27.12 MHz or 40.68 MHz) acting on polar thermoplastics (e.g., PVC, TPU, PETG) to achieve fusion via molecular polarization and frictional heating. Its core mechanisms are as follows:

1. Molecular Polarization and Frictional Heating
   Under a high-frequency electric field, dipoles in plastic molecules oscillate rapidly in alignment with the field direction, generating intense intermolecular friction that converts electrical energy into thermal energy.

2. Precise Temperature Control and Localized Heating
   High-frequency energy concentrates on the material’s surface layer, avoiding thermal deformation of the entire structure.

3. Seamless Fusion and Joint-Free Structure
   Molecular cross-fusion creates seamless connections without adhesive residues or mechanical indentations, minimizing contamination risks in nutrient solutions. Clinical data show that microbial contamination rates in high-frequency welded nutrient bags are <0.01%, outperforming traditional heat-sealing methods.

II. Core Applications of High-Frequency Welding in Nutrient Bag Production

1. Precision Bonding of Liquid Bags and Soft Tubing

   • Material Compatibility: Supports welding of PVC, TPU, silicone, and other materials to meet diverse nutrient fluid delivery requirements.

2. Welding of Multi-Layer Composite Materials

   • Functional Layered Design:
     • Outer PE layer provides mechanical strength.
     • Inner EVA layer ensures biocompatibility.
       High-frequency welding achieves uniform fusion across layers.
   • Biodegradable Material Integration:
     With the growing adoption of biodegradable materials (e.g., PLA, PBS), high-frequency welding adapts via dynamic frequency modulation to match varying dielectric constants, enabling damage-free welding.