Reflective waterproof and breathable membrane construction The working principle of waterproof and breathable membrane can be divided into two types: micropore and hydrophilic group. It is only about 0.0004 microns, and there is a huge difference in the diameters of the two. Water vapor can pass through the microporous membrane by the dispersion principle, and liquid water or water droplets are due to the effect of surface tension.

It prevents water molecules from passing through, which avoids water infiltration and makes the breathable film waterproof. The polypropylene film of spunbond polyethylene and polypropylene film generally refers to biaxially oriented polypropylene film, biaxially oriented polypropylene film. The film (BOPP) is usually a multi-layer pneumatic film. After the polypropylene particles are pneumatically formed into a sheet, they are made by stretching in two directions, due to the stretching of the molecular direction.

The film has excellent physical stability, mechanical strength, air tightness, high transparency and gloss, tough, wear-resistant, widely used printing film, the thickness is generally 20 ~ 40 m, the most widely used is 20 m, two-way stretch The main disadvantage of the stretched polypropylene film is its weak heat sealability, so it is generally used as the outer film of the composite film such as moisture-proof, transparent, strength, rigidity and printability after being compounded with the polyethylene film. The surface of the stretched polypropylene film is non-polar, high in crystallinity, and low in surface free energy, which leads to a decrease in printing performance and a decrease in adhesion to ink and adhesives. Surface treatment is required before printing and lamination.