The influence of high-frequency welding on the compatibility of blood bag materials: The compatibility of materials such as PVC and TPU

I. Compatibility of High-Frequency Welding with Blood Bag Manufacturing

High-frequency welding (also known as dielectric or radiofrequency welding) uses high-frequency alternating electric fields to polarize and thermally fuse polar plastic molecules through internal friction heating. Its core advantages include:

1. Internal-to-external heating: Eliminates surface overheating issues common in hot-plate or hot-air welding, ideal for heat-sensitive materials like PVC.
2. High-speed welding: Suitable for large-scale blood bag production.
3. Exceptional weld strength: Meets pressure resistance requirements for blood bags.
4. Automation compatibility: Integrates laser marking and auto-feeding modules to boost productivity.

II. Adaptability of High-Frequency Welding for PVC Materials

1. Advantages

• Material Properties:
  • High transparency for blood visibility.
  • Flexibility for freeze-thaw storage and transport.
  • Resistance to high-temperature sterilization (e.g., ethylene oxide, gamma-ray).
• Mature Welding Process:
  • HF welding is the industry standard for PVC blood bags.
  • Precision control of parameters (power, time, pressure) via servo motors ensures consistent welds.
  • Low defect rates (<0.1%) with edge control and real-time monitoring systems.

2. Challenges

• Material Stability:
  • Dielectric loss factor increases with temperature, requiring dynamic power tuning to prevent localized overheating.
  • Long-term plasticizer migration necessitates medical-grade PVC compliant with ISO 10993 biocompatibility standards.
• Environmental Sensitivity:
  • Weld quality depends on ambient temperature and humidity; requires dry, dust-free environments.

III. Adaptability of High-Frequency Welding for TPU Materials

1. Advantages

• Superior Material Performance:
  • TPU (thermoplastic polyurethane) offers elasticity and puncture resistance, ideal for blood bags requiring frequent compression.
  • Excellent biocompatibility (ISO 10993 compliance) and non-toxic emissions during welding align with green manufacturing.
• Feasible Welding:
  • As a polar material, TPU achieves robust HF welds with strength approaching that of the base material.
  • Proven in inflatable medical products (e.g., air mattresses), indicating potential for blood bag applications.