# US 2020/0399435 A1 · Graphite sheet polyimide film comprising graphene-containing spherical pi-based filler, manufacturing method therefor, and graphite sheet manufactured using same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0399435 A1 - Document ID: US20200399435A1 - Status: Published application - Kind: A1 - Application number: 16/975,574 - Filed: 2018-07-20 - Published: 2020-12-24 - Earliest claimed: 2018-02-28 - Assignees: PI Advanced Materials Co., Ltd. - Applicants: Pi Advanced Materials Co., Ltd. - Inventors: Kyung Su KIM; Jeong Yeul CHOI; Dong Young WON - Web page: https://patentgrep.com/patent/US20200399435A1 ## CPC - C01B 32/205: Preparation - C08J 5/18: Manufacture of films or sheets - C04B 35/52: based on carbon, e.g. graphite - C04B 35/622: Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products - C08K 3/042: {Graphene or derivatives, e.g. graphene oxides} - C08K 9/04: Ingredients treated with organic substances {(treated with macromolecular compounds C08K9/08)} - C08L 79/08: Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors - C08J 2379/08: Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors - C08K 3/013: Fillers, pigments or reinforcing additives - C08K 9/10: Encapsulated ingredients - C08K 2003/265: {Calcium, strontium or barium carbonate} - C08K 2003/3045: {Sulfates} - C08K 2003/325: {Calcium, strontium or barium phosphate} - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} - C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29) - C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE - C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09) - C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06) ## Abstract The present invention provides a graphite sheet polyimide film derived from a first precursor composition comprising a first polyamic acid, the polyimide film comprising a sublimable inorganic filler and a graphene-containing spherical polyimide-based filler. ## Claims ### Claim 1 A polyimide film for graphite sheets derived from a precursor composition comprising a first polyamic acid, the polyimide film comprising: sublimable inorganic fillers; and graphene-containing spherical polyimide fillers. ### Claim 2 (depends on 1) The polyimide film according to claim 1, wherein the inorganic fillers are present in an amount of 0.2 parts by weight to 0.5 parts by weight relative to 100 parts by weight of the first polyamic acid and the polyimide fillers are present in an amount of 0.1 parts by weight to 5 parts by weight relative to 100 parts by weight of the first polyamic acid. ### Claim 3 (depends on 1) The polyimide film according to claim 1, wherein the inorganic fillers have an average particle diameter of 1.5 μm to 4.5 μm and the polyimide fillers have an average particle diameter of 1 μm to 10 μm. ### Claim 4 (depends on 1) The polyimide film according to claim 1, wherein the inorganic fillers comprise at least one type of inorganic particles selected from the group consisting of dicalcium phosphate, barium sulfate and calcium carbonate. ### Claim 5 (depends on 1) The polyimide film according to claim 1, wherein the polyimide fillers comprise second polyimide chains derived from a second polyamic acid and contain 1 part by weight to 5 parts by weight of graphene relative to 100 parts by weight of the second polyamic acid. ### Claim 6 (depends on 5) The polyimide film according to claim 5, wherein a composition of monomers constituting the second polyamic acid is the same as or different from a composition of monomers constituting the first polyamic acid. ### Claim 7 (depends on 1) The polyimide film according to claim 1, wherein the polyimide film comprises first polyimide chains derived from the first polyamic acid, at least some of the first polyimide chains are aligned in a plane direction to form a multilayer structure, and at least some of the polyimide fillers are dispersed between layers of the multilayer structure. ### Claim 8 (depends on 7) The polyimide film according to claim 7, wherein, upon carbonization and/or graphitization of the polyimide film, at least part of the multilayer structure of the first polyimide chains is graphitized to form a multilayer graphite structure and at least part of the polyimide fillers is graphitized to form a linking portion connecting layers of the multilayer graphite structure to each other. ### Claim 9 (depends on 8) The polyimide film according to claim 8, wherein the linking portion comprises a first linking portion formed by graphitization of second polyimide chains of the polyimide fillers and a second linking portion derived from the graphene of the polyimide fillers. ### Claim 10 (depends on 1) A method of manufacturing the polyimide film according to claim 1, comprising: (a) mixing an organic solvent, a diamine monomer and a dianhydride monomer to prepare a first polyamic acid solution; (b) mixing inorganic fillers and polyimide fillers with the first polyamic acid solution to prepare a first precursor composition; (c) forming a gel film by casting the first precursor composition onto a support, followed by drying the first precursor composition; and (d) imidizing the first precursor composition through heat treatment of the gel film to form a polyimide film. ### Claim 11 (depends on 10) The method according to claim 10, wherein, in Step (b), a first catalyst having a linear structure and a second catalyst having a ring structure are further added to the first polyamic acid solution. ### Claim 12 (depends on 11) The method according to claim 11, wherein the first catalyst comprises at least one selected from the group consisting of dimethylacetamide (DMAc), N,N-diethylacetamide, dimethylformamide (DMF), and diethylformamide (DEF). ### Claim 13 (depends on 11) The method according to claim 11, wherein the first catalyst is dimethylformamide. ### Claim 14 (depends on 11) The method according to claim 11, wherein the second catalyst is N-methyl-2-pyrrolidone (NMP). ### Claim 15 (depends on 11) The method according to claim 11, wherein the first catalyst and the second catalyst are added in a total amount of 1.5 moles to 4.5 moles per 1 mole of an amic acid group in a polyamic acid. ### Claim 16 (depends on 11) The method according to claim 11, wherein the first catalyst is present in an amount of 10 mol % to 30 mol % based on the total amount of the first catalyst and the second catalyst. ### Claim 17 (depends on 10) The method according to claim 10, wherein, in Step (b), a dehydration agent and an imidization agent are further added to the first polyamic acid solution. ### Claim 18 (depends on 1) A graphite sheet manufactured through carbonization and/or graphitization of the polyimide film according to claim 1. ### Claim 19 (depends on 18) The graphite sheet according to claim 18, wherein the graphite sheet has a thickness of 10 μm to 100 μm. ### Claim 20 (depends on 18) The graphite sheet according to claim 18, wherein the graphite sheet has a thermal conductivity of 1,000 W/m·K or more in a plane direction thereof. ### Claim 21 (depends on 18) The graphite sheet according to claim 18, wherein the graphite sheet has a thermal conductivity of 60 W/m·K or more in a thickness direction thereof. ### Claim 22 (depends on 18) An electronic device comprising the graphite sheet according to claim 18.