▎ 摘　　要

NOVELTY - Composite film comprises modified graphene film and modified polyethylene thermal insulation film, and is prepared by (i) preparing modified polyethylene thermal insulation film by (a) uniformly mixing deionized water with anhydrous ethanol, heating in water bath at 45 degrees C, adding coupling agent, and magnetically stirring to obtain mixed solution, ball milling chitosan, adding mixed solution, uniformly stirring, performing suction filtration, washing with absolute ethanol, transferring to 80 degrees C vacuum drying oven, drying, and (b) preliminary treating chitosan particles, polyethylene particles, aminopropylmethyldiethoxysilane and pentaerythritol diphosphite, uniformly mixing, drying, heating, and reacting at 150-205 degrees C for 2 hours to obtain mixed melt, casting obtained mixed melt to film to obtain thermal insulation film, and (ii) compounding modified polyethylene thermal insulation film and modified graphene film using binder. USE - The composite film is useful in surface of building material. ADVANTAGE - The composite film has excellent corrosion-resistant and thermal insulation, reduces the surface energy of modified graphene film, enhances the composite ability with substrate, ensures strong Van der Waals force and conjugation force between graphene, which makes easy to form three-dimensional structure and excellent dispersion in organic and aqueous solvents, and prepares the graphene, which is not uniformly composite with substrate. DETAILED DESCRIPTION - Composite film comprises modified graphene film and modified polyethylene thermal insulation film, and is prepared by (i) preparing modified polyethylene thermal insulation film by (a) uniformly mixing deionized water with anhydrous ethanol in a weight ratio of 10:1, heating in water bath at 45 degrees C, adding coupling agent, and magnetically stirring for 30 minutes to obtain mixed solution, ball milling chitosan, controlling the ball milling speed at 300 rpm, ball-milling for 2 hours, adding mixed solution, uniformly stirring at a rotating speed of 120 rpm for 2 hours, performing suction filtration, washing with absolute ethanol for 3 times, transferring to 80 degrees C vacuum drying oven, drying for 5 hours, controlling the vacuum degree of vacuum drying oven to 0.10 MPa, and controlling the weight ratio of chitosan and mixed liquid to 1:(10-13), and (b) preliminary treating chitosan particles, polyethylene particles, aminopropylmethyldiethoxysilane and pentaerythritol diphosphite, uniformly mixing, drying at 110 degrees C for 4 hours, heating at 150-205 degrees C, and reacting at 150-205 degrees C for 2 hours to obtain mixed melt, casting obtained mixed melt to film to obtain thermal insulation film, and controlling the weight ratio of chitosan particles, polyethylene particles, aminopropylmethyldiethoxysilane and pentaerythritol diphosphite to (0.8-1):(95-98):(8-10):(8-10) after preliminary treatment is performed, and (ii) compounding modified polyethylene thermal insulation film and modified graphene film using binder to obtain the composite film. An INDEPENDENT CLAIM is included for a method for preparing the composite film using above-mentioned method.