▎ 摘　　要

NOVELTY - Preparing composite film comprises (1) adding hexagonal boron nitride into sodium hydroxide solution, heating and stirring reaction, and drying to obtain pre-treated boron nitride powder, (2) dispersing pre-treated boron nitride powder in deionized water, adding aminosilane coupling agent, and drying to obtain modified hexagonal boron nitride, (3) dispersing graphene oxide and double-ended amino silicone oil in isopropanol solvent, adding epichlorohydrin and sodium hydroxide, and drying to obtain modified graphene oxide, (4) dispersing modified hexagonal boron nitride and modified graphene oxide in dimethylformamide, adding tetrabromophthalic anhydride, filtering, and drying to obtain hexagonal boron nitride-graphene oxide composite material, and (5) adding hexagonal boron nitride-graphene oxide composite material to polyvinyl alcohol aqueous solution, and dispersing to obtain film solution, spreading film solution on PET film, drying and releasing film to obtain product. USE - The composite film is useful in light-emitting diode (LED) packaging (claimed). ADVANTAGE - The prepared composite film has excellent mechanical property, light transmission performance and heat conducting performance. DETAILED DESCRIPTION - Preparing composite film comprises (1) adding hexagonal boron nitride into the sodium hydroxide solution, heating and stirring reaction, completing the reaction, filtering the reaction product, washing, and drying to obtain pre-treated boron nitride powder, (2) dispersing the pre-treated boron nitride powder in deionized water, adding aminosilane coupling agent, carrying out stirring reaction, completing the reaction, filtering the reaction product, washing and drying to obtain modified hexagonal boron nitride, (3) dispersing graphene oxide and double-ended amino silicone oil in isopropanol solvent, adding epichlorohydrin and sodium hydroxide, heating and stirring at 80-90℃ for 2-3 hours, completing the reaction, filtering the reaction product, washing, and drying to obtain modified graphene oxide, (4) dispersing modified hexagonal boron nitride and modified graphene oxide in dimethylformamide solvent, adding tetrabromophthalic anhydride, reacting at room temperature for 3-5 hours, completing the reaction, filtering the reaction product, washing, and drying to obtain a hexagonal boron nitride-graphene oxide composite material, and (5) adding the hexagonal boron nitride-graphene oxide composite material into the polyvinyl alcohol aqueous solution, stirring and mixing evenly, and performing ultrasonic dispersion to obtain the film solution, spreading the film solution on the PET film, drying at 35-40℃ for 2-4 hours, and releasing the film from the PET film to obtain composite film. An INDEPENDENT CLAIM is also included for composite film.