The material of the composite membrane includes any possible combination of materials, such as a ceramic membrane on a metal oxide or an aromatic polyamide film on a polysulfone microporous membrane, and the flat membrane or roll membrane must be made of non-woven fabrics. Reinforced to support the pressure resistance of microporous membranes, while hollow fiber membranes do not.Composite film manufacturing methods are divided into four categories: (1)Lamination method, first prepare a very thin dense homogeneous membrane, and then laminate it on the microporous support membrane; (2)Dip coating method, the polymer solution is dip-coated on the microporous membrane, and then dried, or the active monomer or prepolymer solution can be dip-coated on the microporous membrane, and cured by heat or radiation; (3)Plasma vapor deposition method, using plasma glow to produce a dense homogeneous film on the surface of the microporous support film; (4)In the interfacial polymerization method, the active monomer is used for interfacial polymerization on the surface of the microporous support membrane.Composite membranes are mainly used in separation processes such as reverse osmosis, gas separation, and pervaporation.Two kinds of roll film materials are used to make a membrane composed of a surface active layer (dense separation layer) with separation function and a porous layer with supporting function.Composite roll film is to paste geotextile on one or both sides of the film to form a composite geomembrane. Its form has one cloth and one film, two cloth and one film. Width4-6m, with a weight of200—1500g/Square meters, high physical and mechanical properties such as tensile, tear resistance, and bursting, the product has the advantages of high strength, good elongation, large deformation modulus, acid and alkali resistance, corrosion resistance, aging resistance, and good impermeability, etc. . It can meet the needs of civil engineering such as anti-seepage, isolation, reinforcement, crack prevention and reinforcement in water conservancy, municipal administration, construction, transportation, subway, tunnel, and engineering construction. Due to the selection of polymer materials and the addition of anti-aging agents in the production process, it can be used in unconventional temperature environments. It is often used in the anti-seepage treatment of dams and drainage ditches, and the anti-pollution treatment of waste yards.