▎ 摘　　要

NOVELTY - Artificial graphite sheet is prepared by laminating several layers of polyimide films and performing carbonization and graphitization treatment, the preparation method of the polyimide film involves i. dissolving the diamine monomer in an organic solvent to obtain a diamine solution in an inert atmosphere, ii. adding micron-scale inorganic particles and nano-scale inorganic particles to the diamine solution, stirring and dispersing evenly to obtain a dispersion; the micron-scale inorganic particles graphene, graphene oxide, and/or reduced graphene oxide, and the amount of inorganic particles added is 0.1-5 wt.% diamine monomer; iii. adding dianhydride monomers to the dispersion obtained in step (ii), stirring and reacting to obtain a polyamic acid solution; iv. adding catalyst and a dehydrating agent to the polyamic acid solution, and a partially imidized polyamic acid solution is obtained after the reaction at room temperature. USE - Artificial graphite sheet for use in heat sink (claimed). ADVANTAGE - The artificial graphite sheet has high vertical heat conductivity and maintains excellent horizontal heat conductivity and flexibility. DETAILED DESCRIPTION - Artificial graphite sheet is prepared by laminating several layers of polyimide films and performing carbonization and graphitization treatment, the preparation method of the polyimide film involves i. dissolving the diamine monomer in an organic solvent to obtain a diamine solution in an inert atmosphere, ii. adding micron-scale inorganic particles and nano-scale inorganic particles to the diamine solution, stirring and dispersing evenly to obtain a dispersion; the micron-scale inorganic particles graphene, graphene oxide, and/or reduced graphene oxide, and the micron-scale inorganic particles have at least one dimension 1-20 μm, the amount of inorganic particles added is 0.1-5 wt.% diamine monomer. The nanoscale inorganic particles is hydrogen phosphate and/or dihydrogen phosphate. The particle size of the nanoscale inorganic particles is 10-100 nm, the addition amount of the nanoscale inorganic particles is diamine 0.1-5 wt.% monomer mass; iii. adding dianhydride monomers to the dispersion obtained in step (ii), stirring and reacting to obtain a polyamic acid solution; iv. adding catalyst and a dehydrating agent to the polyamic acid solution, and a partially imidized polyamic acid solution is obtained after the reaction at room temperature; the molar ratio of the added catalyst and the dianhydride monomer is 0.1-0.4:1, and molar ratio of the dehydrating agent and the dianhydride monomers is 0.2-0.8:1; v. coating the partially imidized polyamic acid solution on the surface of the base film to form a wet film, and the polyimide film is obtained after thermal curing. An INDEPENDENT CLAIM is included for a heat sink, which comprises a high vertical thermal conductivity artificial graphite sheet, and a metal copper foil and a polyethylene terephthalate release film respectively arranged on both sides of the artificial graphite sheet. The metal copper foil and the PET release film are bonded to the artificial graphite sheet through a thermally conductive double-sided adhesive layer.