Production process of waterproof breathable membrane

1. Casting compound. The technology of waterproof breathable membrane was introduced from European and American countries earlier. However, the production process of domestic products is varied, and the quality of products of various manufacturers is uneven, and a unified quality standard has not been formed. In fact, the waterproof breathable membrane is mainly composed of three layers: PP spunbond non-woven fabric, PE polymer breathable membrane, and PP spunbond non-woven fabric. The function of spunbond non-woven fabric is mainly to enhance the tensile force and hydrostatic pressure and protect the middle layer (breathable film). The real breathability mainly depends on the middle layer of PE polymer breathable film. This process relies on the viscosity of the plastic itself after hot-melting plastic particles.

2. Glue spray or squeegee compounding (hot melt adhesive compounding). This process has long been used in sanitary napkins, diapers, and protective clothing. At present, almost all domestic manufacturers use this process to produce highly breathable waterproof and breathable materials.

3. Hot pressing compound. In the state of water vapor, the water particles of the waterproof and breathable membrane are very small. According to the principle of capillary motion, it can smoothly penetrate into the capillary to the other side, thereby causing the phenomenon of vapor permeability. When the water vapor condenses into water droplets, the particles become larger. Due to the surface tension of the water droplets (the water molecules "pull and compete with each other"), the water molecules cannot smoothly escape from the water droplets and penetrate to the other side, which is to prevent the The permeation of water occurs, making the vapor permeable membrane waterproof. At present, the domestic market is mixed, and there are actually very few manufacturers producing real waterproof and breathable membranes. Many factories or sellers say that their waterproof and breathable membranes are good.