FTTS-FA-005 Water-Vapor Permeable and Liquid-Water Impermeable Textiles

Water-Vapor Permeable & Liquid-Water Impermeable Textiles allow vapor to pass through but not liquid. Thus perspiration vapor readily departs from the skin, while water outside the garment cannot enter. The inside of the garment remains free of moisture droplet and the wearer stays warm and dry. Water-vapor permeability means the vapor emitted from the surface of an exercising body can evaporate outside the textile, so the temperature decreases and the wearer maintains ultimate comfortableness and dryness. Liquid-water Impermeability means the textile resists water penetration. Most commonly, the surface of this type of textile is coated with PU, PTFE, TPU, TPE or other materials. The same effect can also be achieved by laminating fabric with a water-impermeable film.

Water-vapor permeable & liquid-water impermeable textiles are manufactured in three ways:
1. Direct coating
2. Lamination
3. High-density woven fabrics

The micro-porous resin or film contains thousands of micro-porous on every square-centimeter of surface. These apertures are far smaller than water droplet. Consequently, even under pressure the materials completely prevent water from penetrating while simultaneously driving out moisture from inside.

Hydrophilic materials utilize the hydrophilic group to absorb moisture which then evaporates through diffusion and air convection. Manufactured for specific environmental demands, water-vapor permeable & liquid-water impermeable textiles are available on different combinations of hydrostatic pressure endurance and water-vapor permeability.

With current technology in Taiwan, water-vapor permeable & liquid-water impermeable textiles made by lamination can possess a hydrostatic pressure endurance of at least 40,000 mmH2O (ISO 811), a water-vapor permeability of at least 20,000 g/m2‧24hr (JIS L1099-B1) and a RET of 6 m2pa/w or less. Their counterparts made by direct coating can possess a hydrostatic pressure endurance of at least 10,000mmH2O (ISO 811) and a water-vapor permeability of at least 10,000 g/m2‧24hr (JIS L1099-B1).

This criterion is applicable to the evaluation and testing of water vapor permeability & water resistance of textiles