Production process of waterproof and breathable membrane

The production processes of waterproof and breathable membranes are mainly divided into two categories: flash evaporation method and stretching method. The flash evaporation method is a nonwoven production method, also known as the instant solvent evaporation web method. It uses dry spinning technology instead of melt spinning, which is made by dissolving the polymer in a certain solvent. The spinning liquid is then ejected from the spinneret, and the polymer is recirculated into fibers due to the rapid evaporation of the solvent. At the same time, the spinning technology used in the flash evaporation method is different from ordinary dry spinning. This is mainly reflected in the fact that the flash evaporation process uses a lower viscosity of the spinning solution, and uses extremely high pressure and speed to spin the spinneret. Squirting out of the hole. Due to the low viscosity and good fluidity of the solution, the liquid filaments solidify during high-speed movement to form extremely fine fiber filaments, which are finally adsorbed on the mesh curtain to directly form a fiber mesh. The polyethylene non-woven fiber produced by this method can be as thin as 0.1 dtex (1 dtex=0.1 mg/m). Therefore, it has excellent waterproof and breathable properties and can isolate many chemical liquids and dry and wet particles. Being immersed in water does not affect its physical properties, and at the same time allows enough air and water vapor to penetrate; the fiber has high crystallinity, good orientation, and continuous fibers, so the sheet has excellent strength, tear resistance, and puncture resistance. , The bursting strength is 2-3 times that of polypropylene non-woven fabrics; because the electrostatic method can keep the fibers in a single state, the texture of the sheet is very uniform.