Composite film with dust, haze and water prevention and air permeability functions and preparation method thereof

The invention relates to a composite film with dust, haze and water prevention and air permeability functions and a preparation method thereof. The composite film comprises an intermediate layer and non-woven layers, wherein the intermediate layer is a waterproof breathable membrane, and the non-woven layers are respectively arranged on both the inner and outer sides of the waterproof breathable membrane. The preparation method of the composite film comprises the following steps: mixing a hydrophilic polymer and any one out of dimethyl formamide, acetone or tetrahydrofuran uniformly at room temperature to obtain the solution of the hydrophilic polymer; stirring and mixing a hydrophobic polymer and trichloromethane uniformly at room temperature to obtain the solution of the hydrophobic polymer; feeding the solution of the hydrophobic polymer into a propelling pump, and spraying the charged solution of the hydrophobic polymer to an aluminum foil receiver below the propelling pump to obtain a hydrophobic film; and adding the solution of the hydrophilic polymer into a propelling pump, and spraying the charged solution of the hydrophilic polymer to the hydrophobic film to obtain the waterproof breathable membrane. Compared with the prior art, the three-layer composite film has the advantages that the inner and outer non-woven layers mainly have functions of increasing the strength of the composite film and resisting ultraviolet light and flame, and the intermediate layer which is the microporous membrane has water prevention and air permeability functions.