The manufacturing methods of composite film are divided into four categories:

(1) The lamination method is to first prepare a thin, dense and homogeneous membrane, and then laminate it on the microporous support membrane;

(2) Dip coating method: the polymer solution is dipped and coated on the microporous membrane, and then dried. The active monomer or prepolymer solution can also be dipped and coated on the microporous membrane, and cured by heat or radiation;

(3) The plasma gas phase stacking method uses the plasma glow to make the surface of the microporous support film form a fine homogeneous film;

(4) Interfacial polymerization method: on the surface of microporous support membrane, the active monomer is used for interfacial polymerization.

The composite membrane is mainly used in reverse osmosis, gas separation, infiltration transpiration and other processes.

Using two different kinds of film rolling materials, the aluminum foil composite film is respectively made into a film composed of an external active layer (fine and dense separate layer) with different functions and a porous layer with supporting function.