Why is the moisture permeability of breathable TPU film 5-6 times higher than that of ordinary TPU film?

The moisture permeability of breathable TPU film is 5 - 6 times higher than that of ordinary TPU film, primarily due to its unique molecular structure design, material modification techniques, and optimized production processes. Here are the specific reasons:

1. Molecular Structure Design

· Introduction of Hydrophilic Groups: Breathable TPU film incorporates polar groups (such as polyether or polyester segments) into the molecular chain, enhancing the material's interaction with water molecules. This hydrophilicity allows the film to adsorb water molecules in high-humidity environments and transport them to low-humidity areas through chain segment movement, achieving moisture-wicking and breathability.

· Dense and Pore-Free Structure: Unlike ordinary TPU films, breathable TPU films adopt a dense and pore-free structure, forming continuous moisture-permeable channels through the microscopic arrangement of molecular chains. This structure prevents the penetration of liquid water while allowing water vapor to pass through at the molecular level, significantly improving moisture permeability.

2. Material Modification Techniques

· Copolymerization Modification: By combining different chain segments through copolymerization reactions, such as introducing hydrophilic segments into TPU, the moisture permeability of the material can be effectively enhanced. This modification method maintains the mechanical properties of the material while improving its moisture-permeable capability.

· Nanocomposite Technology: Dispersing nanoscale fillers (such as nano-silica, montmorillonite, etc.) into the TPU matrix can form nanoscale channels, further facilitating the transmission of water vapor.

3. Optimized Production Processes

· Film Thickness Control: Breathable TPU films typically adopt an ultra-thin design (with thicknesses as low as 0.008 - 0.020 mm). The reduced thickness shortens the water vapor transmission path, thereby improving moisture permeability efficiency.

· Stretch Orientation Process: Stretching the film to align the molecular chains in a specific direction forms an oriented structure, which can enhance the film's moisture permeability. This process optimizes the moisture-permeable channels while maintaining the film's strength.

4. Performance Comparison

· Difference in Moisture Permeability Rate: The moisture permeability rate of breathable TPU films can reach 2000 - 10000 grams per square meter per 24 hours (g/m²·24h), while that of ordinary TPU films usually ranges from 500 - 1500 g/m²·24h. This significant difference stems from the combined effects of the aforementioned molecular structure design and process optimization.

· Application Scenarios: Breathable TPU films are widely used in outdoor clothing, medical protective clothing, sports equipment, and other fields. Their high moisture permeability effectively expels body sweat, keeping the skin dry and enhancing wearing comfort.