Sterilization compatibility and long-term stability of high-frequency welding process for TPU calendered film

In the medical, food packaging, and high-end industrial fields, TPU calendered film is widely used due to its excellent elasticity, biocompatibility, and chemical resistance. High-frequency welding technology, with its molecular-level fusion characteristics, not only enhances connection strength but also demonstrates unparalleled advantages in sterilization compatibility and long-term stability compared to traditional processes, making it a core technology for flexible container manufacturing.

I. Sterilization Compatibility: Unfazed by Harsh Environments, Safeguarding Safety

1. Ethylene Oxide (EO) Sterilization: Chemical Inertness Creates a Safety Barrier

The high-frequency welding process for TPU calendered film achieves molecular fusion through electromagnetic induction heating, leaving no adhesive, solvent, or other chemical residues at the welding interface. During EO sterilization, this pure molecular structure avoids the risk of interaction between chemicals and sterilizing agents, preventing potentially harmful byproducts after sterilization. Simultaneously, the TPU material itself has good permeability and resistance to EO gas, and the tightly packed molecular arrangement in the welded area ensures no micropores or cracks after sterilization, guaranteeing the long-term sterility of the container.

2. Gamma-ray Irradiation Sterilization: Molecular Stability Resists Radiation Damage

The interpenetrating polymer network structure formed by high-frequency welding ensures the high stability of TPU molecular chains under irradiation. Compared to traditional bonding processes, the welded interface eliminates the "weak link" of the adhesive layer, avoiding adhesive degradation or cross-linking reactions caused by irradiation. Even after high-dose gamma-ray irradiation, the molecular chains in the welded area maintain their original arrangement, ensuring that the material's mechanical properties and sealing performance are unaffected, meeting the requirements of medical products.

3. High-Pressure Steam Sterilization: Overcoming Traditional Limitations in Temperature and Humidity Resistance

For flexible containers requiring repeated sterilization, high-frequency welded TPU calendered films exhibit superior high-temperature and high-humidity resistance. The welded interface forms a dense layer due to molecular fusion, eliminating the risk of adhesive layer hydrolysis or detachment in humid and hot environments. In a high-pressure steam environment, the welded area expands and contracts synchronously with the base material, avoiding debonding or leakage caused by thermal stress in traditional bonding, ensuring the reliability and repeatability of the sterilization process.

II. Long-Term Stability: Molecular-Level Fusion for Durable Performance

1. Stable Molecular Structure: A Qualitative Change from "Splicing" to "Integration"

High-frequency welding utilizes electromagnetic induction to induce resonance and frictional heating of polar groups within the TPU molecular chains, achieving molecular-level "welding." This connection method creates an interface with a molecular structure identical to the base material, free from chemical additives or physical defects. It eliminates the performance degradation issues caused by adhesive layer aging and stress concentration in traditional bonding processes. During long-term use, the welded area ages synchronously with the base material, maintaining performance consistency.

2. Environmental Aging Resistance: Unfazed by Time and Environment

After long-term environmental testing (such as high temperature and humidity, UV radiation, ozone aging, etc.), high-frequency welded TPU calendered film products showed no cracking, discoloration, or debonding at the weld interface. This is attributed to the interpenetrating network structure formed during the welding process, which effectively disperses environmental stress and inhibits material oxidative degradation. For example, in flexible storage tanks used outdoors for extended periods, high-frequency welded products can maintain stable performance for decades, while traditional adhesive products may fail within 5-10 years due to adhesive layer aging.

3. Dynamic Sealing Performance: Durable Resistance to Fatigue and Stress

In scenarios involving repeated filling, folding, or vibration of flexible containers, high-frequency welded TPU calendered films exhibit superior fatigue resistance. The welded area, due to the mechanical interlocking effect formed by interpenetrating molecular chains, demonstrates a tear resistance several times higher than that of planar welding, capable of withstanding tens of thousands of cyclic loading cycles without cracking. In contrast, traditional adhesive layers are prone to debonding or microcracks under dynamic stress, leading to a rapid decline in sealing performance, while high-frequency welded products can maintain a "zero-leakage" state for extended periods.