WO2019187620A1 - Graphite sheet and method for producing same - Google Patents

Graphite sheet and method for producing same Download PDF

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Publication number
WO2019187620A1
WO2019187620A1 PCT/JP2019/003602 JP2019003602W WO2019187620A1 WO 2019187620 A1 WO2019187620 A1 WO 2019187620A1 JP 2019003602 W JP2019003602 W JP 2019003602W WO 2019187620 A1 WO2019187620 A1 WO 2019187620A1
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Prior art keywords
graphite sheet
polyimide film
dianhydride
less
temperature
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PCT/JP2019/003602
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French (fr)
Japanese (ja)
Inventor
幹明 小林
啓介 稲葉
正寛 小島
西川　泰司
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株式会社カネカ
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Priority to JP2020510329A priority Critical patent/JPWO2019187620A1/en
Priority to CN201980009864.0A priority patent/CN111655617A/en
Publication of WO2019187620A1 publication Critical patent/WO2019187620A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/20—Graphite
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/20—Graphite
    • C01B32/205—Preparation
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
    • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
    • C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/36—Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
    • H01L23/36—Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks
    • H01L23/373—Cooling facilitated by selection of materials for the device or materials for thermal expansion adaptation, e.g. carbon

Definitions

  • the present invention relates to a graphite sheet and a manufacturing method thereof.
  • graphite sheets Since graphite sheets have excellent heat dissipation properties, they are used as heat dissipation components in semiconductor devices and other heat generating components mounted on various electronic devices such as computers or electrical devices.
  • Such a graphite sheet can be obtained by baking a polyimide film.
  • Patent Document 1 describes a technique for producing a graphite sheet by baking a polyimide film containing inorganic particles.
  • An object of one embodiment of the present invention is to provide a graphite sheet having good thermal diffusibility and flexibility and a method for producing the same.
  • the present invention includes the following. [1] A graphite sheet having a phosphorus content of 0.01 wt% or more and 0.10 wt% or less.
  • a graphite sheet with good thermal diffusivity and flexibility can be obtained.
  • the method for producing a graphite sheet of one embodiment of the present invention is a method for producing a graphite sheet having a phosphorus content of 0.01 wt% or more and 0.10 wt% or less, and a phosphate content of 0.01 wt%.
  • This manufacturing method is a so-called polymer pyrolysis method in which a polyimide film is heat-treated in an inert gas atmosphere or under reduced pressure. Specifically, the graphite film is preheated to a temperature of about 1000 ° C. to obtain a carbonaceous film, and the carbonaceous film produced in the carbonization step is heated to a temperature of 2600 ° C. or more to graphitize. A graphite sheet is obtained through the conversion step and the compression step of compressing the same. Note that the carbonization step and the graphitization step may be performed continuously, or the carbonization step may be terminated, and then only the graphitization step may be performed alone. Moreover, in the manufacturing method of the graphite sheet of one Embodiment of this invention, it does not need to perform a compression process.
  • a carbonization process is a process of heat-processing a polyimide film to the temperature of about 1000 degreeC, and carbonizing a polyimide film.
  • the maximum temperature is preferably 700 ° C. to 1800 ° C., more preferably 800 ° C. to 1500 ° C., further preferably 900 ° C. to 1200 ° C., and particularly preferably 1000 ° C.
  • the heating rate in the carbonization step is preferably 0.01 ° C./min or more and less than 20 ° C./min, more preferably 0.1 ° C./min to 10 ° C./min, and 0.5 ° C./min. More preferably, it is less than ⁇ 5.0 ° C./min. If the rate of temperature increase is within the above range, a preferable amount of phosphorus in the polyimide film remains, and a graphite sheet having good thermal diffusibility and flexibility can be obtained.
  • the holding time in the carbonization step (specifically, the holding time at the maximum carbonization temperature) is preferably 1 minute to 1 hour, more preferably 5 minutes to 30 minutes, and 8 minutes to 15 minutes. More preferably. If the holding time is within the above range, a preferable amount of phosphorus in the polyimide film remains, and a graphite sheet having good thermal diffusibility and flexibility can be obtained.
  • the laminated polyimide film obtained by laminating the rectangular polyimide film may be carbonized, the roll-shaped polyimide film may be carbonized while being in a roll shape, and the film is drawn out from the roll-shaped polyimide film and carbonized. Also good.
  • the graphitization step is a step of heat-treating the carbonaceous film obtained in the carbonization step to a temperature of 2600 ° C. or higher to graphitize the carbonaceous film.
  • the maximum temperature is preferably 2600 ° C or higher, 2700 ° C or higher, 2800 ° C or higher, 2900 ° C or higher, or 3000 ° C or higher.
  • an upper limit is not specifically limited, It is preferable that it is 3300 degrees C or less, and it is more preferable that it is 3200 degrees C or less.
  • the graphitization step is performed under reduced pressure or in an inert gas. Argon or helium is suitable as the inert gas.
  • the heating rate in the graphitization step is, for example, 0.01 ° C./min or more and less than 20 ° C./min, 0.1 ° C./min to 10 ° C./min, 0.2 ° C./min to 5.0 ° C./min, A preferable example is 0.5 ° C./min to 2.0 ° C./min. If the rate of temperature increase is within the above range, a preferable amount of phosphorus in the polyimide film remains, and a graphite sheet having good thermal diffusibility and flexibility can be obtained.
  • the retention time in the graphitization step (specifically, the retention time at the maximum graphitization temperature) is preferably 1 minute to 1 hour, more preferably 5 minutes to 30 minutes, and more preferably 8 minutes to More preferably, it is 15 minutes. If the holding time is within the above range, a preferable amount of phosphorus in the polyimide film remains, and a graphite sheet having good thermal diffusibility and flexibility can be obtained.
  • a laminated carbonized film in which rectangular carbonized films are laminated may be graphitized, or a roll-shaped carbonized film may be graphitized while being in a roll shape. May be used.
  • compression process You may give a compression process to the carbonaceous film after graphitization. By performing the compression step, flexibility can be imparted to the obtained graphite sheet.
  • a method of compressing in a planar shape, a method of rolling using a metal roll or the like can be used.
  • the compression step may be performed at room temperature or during the graphitization step.
  • the graphite sheet has a phosphorus content of 0.01 wt% to 0.10 wt%, more preferably 0.02 wt% to 0.08 wt%. Within such a range, the physical properties of both thermal diffusibility and flexibility are excellent in the graphite sheet.
  • the thermal diffusivity of the graphite sheet is preferably 7.0 cm 2 / s or more, more preferably 7.3 cm 2 / s or more, further preferably 8.0 cm 2 / s or more .
  • the flexibility of the graphite sheet is preferably “C” or more, more preferably “B” or more, and further preferably “A” or more in the flexibility evaluation of Examples described later. .
  • the thickness of the graphite sheet is preferably 5 ⁇ m to 60 ⁇ m, more preferably 10 ⁇ m to 50 ⁇ m, and further preferably 15 ⁇ m to 40 ⁇ m.
  • the density of the graphite sheet is preferably from 1.0g / cm 3 ⁇ 2.26g / cm 3, more preferably from 1.3g / cm 3 ⁇ 2.2g / cm 3, 1.6g / cm 3 ⁇ 2 More preferably, it is 18 g / cm 3 .
  • the polyimide film for a graphite sheet used in the manufacturing method is a polyimide film using an acid dianhydride component and a diamine component as raw materials, and contains a predetermined amount of phosphate.
  • the polyimide film preferably has a phosphate content of 0.01% to 0.49% by weight, more preferably 0.10% to 0.40% by weight, and 0.12% by weight. More preferably, the content is from 0.3 to 0.35% by weight. Within such a range, the physical properties of both the thermal diffusibility and flexibility of the finally obtained graphite sheet are excellent.
  • Examples of the phosphate that can be used in the embodiment of the present invention include CaHPO 4 , (NH 4 ) 2 HPO 4, and the like. Among them, CaHPO 4 and (NH 4 ) 2 HPO 4 can be preferably used because good swelling occurs due to gas generated when sublimating from the inside of the polyimide film, and good graphite having excellent thermal conductivity is obtained. . Phosphate can be added to the polyimide film as inorganic particles (ie, filler).
  • the acid dianhydride components that can be used are pyromellitic dianhydride, 2,3,6,7, -naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid Dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 1,1- (3,4-dicarboxy Phenyl) ethane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyr
  • the diamine components that can be used are 4,4′-diaminodiphenyl ether, p-phenylenediamine, 4,4′-diaminodiphenylmethane, benzidine, 3,3′-dichlorobenzidine, 4,4′-diaminodiphenyl sulfide, 3,3 '-Diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 4,4'-diaminodiphenyldiethylsilane, 4, 4'-diaminodiphenylsilane, 4,4'-diaminodiphenylethylphosphine oxide, 4,4'-diaminodiphenyl N-methylamine, 4,4'-d
  • the thickness of the polyimide film is 12.5 ⁇ m to 125 ⁇ m, preferably 25 ⁇ m to 100 ⁇ m, more preferably 35 ⁇ m to 75 ⁇ m. If it is in the said range, since it heat-processes uniformly in the thickness direction, thermal diffusivity improves.
  • the polyimide imidization method includes a thermal curing method in which the precursor polyamic acid is heated to convert to imide, or a dehydrating agent typified by an acid anhydride such as acetic anhydride, picoline, quinoline, isoquinoline, pyridine, etc.
  • a dehydrating agent typified by an acid anhydride such as acetic anhydride, picoline, quinoline, isoquinoline, pyridine, etc.
  • Any of the chemical curing methods for converting the polyamic acid, which is a precursor, into an imide, using an imidization accelerator typified by the above tertiary amines may be used.
  • the imidization accelerator in the case of using the chemical cure method, the tertiary amines listed above are preferable.
  • the polyimide film obtained has a low linear expansion coefficient, high modulus of elasticity, high birefringence, and can be rapidly graphitized at a relatively low temperature to obtain a quality graphite sheet. Therefore, the chemical cure method is preferred.
  • the combined use of a dehydrating agent and an imidization accelerator is preferable because the resulting polyimide film has a small linear expansion coefficient, a large elastic modulus, and a large birefringence.
  • the chemical cure method is an industrially advantageous method that can complete the imidization reaction in a short time in the heat treatment because the imidization reaction proceeds faster, and is excellent in productivity.
  • the method for producing the polyamic acid is not particularly limited.
  • the aromatic acid dianhydride and the diamine are dissolved in an organic solvent in a substantially equimolar amount, and the organic solution is dissolved in the aromatic acid dianhydride and the diamine.
  • the polyamic acid can be prepared by stirring under controlled temperature conditions until the polymerization with is complete.
  • the polymerization method is not particularly limited, but for example, any of the following polymerization methods (1) to (5) is preferable. Note that (1) to (5) exemplify cases where an aromatic tetracarboxylic dianhydride is used as the aromatic dianhydride and an aromatic diamine compound is used as the diamine.
  • a specific example of the method (2) is that a prepolymer having the acid dianhydride at both ends is synthesized using a diamine and an acid dianhydride, and the same kind of diamine used for the synthesis of the prepolymer is used for the prepolymer.
  • This method is the same as the method of synthesizing polyamic acid by reacting diamines of different types or different types of diamines.
  • the aromatic diamine compound to be reacted with the prepolymer may be the same kind of aromatic diamine compound as the aromatic diamine compound used for the synthesis of the prepolymer or a different kind of aromatic diamine compound.
  • an aromatic diamine compound is added so as to be substantially equimolar with respect to the acid dianhydride.
  • the present invention can be configured as follows. [1] A graphite sheet having a phosphorus content of 0.01 wt% or more and 0.10 wt% or less. [2] The graphite sheet according to [1], wherein the phosphorus content is 0.02 wt% or more and 0.08 wt% or less.
  • phosphorus content of polyimide film was calculated from the ratio between the molecular weight of the phosphate used and the atomic weight of phosphorus.
  • ⁇ Phosphorus content of graphite sheet> The phosphorus content of the graphite sheet was determined by the ratio of the phosphorus peak of the graphite film to be measured and the phosphorus peak of a substance having a known phosphorus concentration, using an X-ray fluorescence analyzer. Further, ZSX Primus II manufactured by Rigaku Corporation was used as a fluorescent X-ray analyzer, and a polyimide film having a phosphorus concentration of 0.034% by weight was used as a substance having a known phosphorus concentration.
  • the number of bendings (MIT) in the bending resistance test means that the larger the number, the more flexible the graphite sheet and the better the bending resistance. Therefore, even if a graphite sheet having a large number of MITs is used for the bent portion, it is difficult to break.
  • the evaluation criteria were as follows. A: Number of folding times is 100,000 or more B: Number of folding times is 10,000 or more and less than 100,000 times C: Number of folding times is 1000 or more and less than 10,000 times D: Number of folding times is 100 times or more and less than 1000 times E: Number of folding times is less than 100 times ⁇ Thermal diffusivity>
  • the thermal diffusivity of the graphite sheet obtained by the method described later was measured by the following method. Specifically, a graphite sheet sample cut into a 4 mm ⁇ 40 mm shape using a thermal diffusivity measuring apparatus (“LaserPit” manufactured by ULVAC-RIKO Co., Ltd.) based on the optical alternating current method is used in an atmosphere of 20 ° C. And measured under AC conditions of 10 Hz.
  • Drying conditions are as follows. First, the mixed solution layer on the aluminum foil was dried in a hot air oven at 120 ° C. for 240 seconds to form a self-supporting gel film. The gel film was peeled off from the aluminum foil and fixed to the frame. Furthermore, the gel film is heated stepwise in a hot air oven at 120 ° C. for 30 seconds, 275 ° C. for 40 seconds, 400 ° C. for 42 seconds, 450 ° C. for 50 seconds, and a far infrared heater at 460 ° C. for 22 seconds. And dried. As described above, a polyimide film (A-1) having a phosphorus content of 0.034% by weight and a thickness of 50 ⁇ m was produced.
  • Production Example 2 Except that calcium hydrogen phosphate was added to the obtained polyamic acid solution so that the concentration of calcium hydrogen phosphate was 0.05% by weight based on the solid content of the polyamic acid, the same procedure as in Production Example 1 was carried out. A polyimide film (A-2) having a phosphorus content of 0.011% by weight and a thickness of 50 ⁇ m was produced.
  • Production Example 3 Except for adding calcium hydrogen phosphate to the obtained polyamic acid solution so that the concentration of calcium hydrogen phosphate was 0.01% by weight based on the solid content of the polyamic acid, the same procedure as in Production Example 1 was carried out. A polyimide film (A-3) having a phosphorus content of 0.002 wt% and a thickness of 50 ⁇ m was produced.
  • Production Example 7 The same procedure as in Production Example 1 except that calcium carbonate was added to the obtained polyamic acid solution instead of calcium hydrogen phosphate so that the concentration of calcium carbonate was 0.15% by weight based on the solid content of the polyamic acid. Thus, a polyimide film (A-7) having a phosphorus content of 0% by weight and a thickness of 50 ⁇ m was produced.
  • Production Example 8 A phosphorus content of 0 was obtained in the same manner as in Production Example 1, except that calcium hydrogen phosphate was added to the obtained polyamic acid solution so that the concentration was 0.50% by weight based on the solid content of the polyamic acid. A polyimide film (A-8) having a thickness of 114% by weight and a thickness of 50 ⁇ m was produced.
  • Example 1 A polyimide film (A-1) having a size of 200 mm ⁇ 200 mm and a thickness of 50 ⁇ m is sandwiched between graphite sheets having a size of 220 mm ⁇ 220 mm (one polyimide film and a graphite sheet are alternately laminated), and 0.5% in a nitrogen atmosphere. The temperature was raised to 1000 ° C. at a rate of temperature rise / ° C./min, and then heat treated at 1000 ° C. for 10 minutes for carbonization.
  • the graphite sheet was produced by holding at 2800 ° C. for 10 minutes.
  • One piece of the obtained graphite sheet was sandwiched between PET films having a size of 200 mm ⁇ 200 mm ⁇ thickness of 400 ⁇ m, and compression processing was performed using a compression molding machine.
  • the applied pressure was 10 MPa.
  • the graphite sheet after compression had a thickness of 25 ⁇ m and a density of 1.83 g / cm 3 .
  • Example 2 A graphite sheet of Example 2 was produced in the same manner as in Example 1 except that the temperature was raised to 2800 ° C. (graphitization maximum temperature) at a rate of temperature increase of 0.5 ° C./min.
  • the compressed graphite sheet had a thickness of 24 ⁇ m and a density of 1.9 g / cm 3 .
  • Example 3 A graphite sheet of Example 3 was produced in the same manner as in Example 1 except that the temperature was raised to 2800 ° C. (graphitization maximum temperature) at a rate of temperature rise of 0.1 ° C./min.
  • the graphite sheet after compression had a thickness of 23 ⁇ m and a density of 1.99 g / cm 3 .
  • Example 4 A graphite sheet of Example 4 was produced in the same manner as in Example 1 except that the polyimide film (A-2) was used instead of the polyimide film (A-1).
  • the graphite sheet after compression had a thickness of 23 ⁇ m and a density of 1.99 g / cm 3 .
  • Example 5 A graphite sheet of Example 5 was produced in the same manner as in Example 1 except that the polyimide film (A-3) was used instead of the polyimide film (A-1).
  • the compressed graphite sheet had a thickness of 22 ⁇ m and a density of 2.08 g / cm 3 .
  • Example 6 A graphite sheet of Example 6 was produced in the same manner as Example 3 except that the polyimide film (A-4) was used instead of the polyimide film (A-1).
  • the compressed graphite sheet had a thickness of 26 ⁇ m and a density of 1.76 g / cm 3 .
  • Example 7 A graphite sheet of Example 7 was produced in the same manner as in Example 1 except that the temperature was raised to 2600 ° C. (graphitization maximum temperature) at a rate of temperature increase of 5.0 ° C./min.
  • the graphite sheet after compression had a thickness of 27 ⁇ m and a density of 1.69 g / cm 3 .
  • Example 8 A graphite sheet of Example 7 was produced in the same manner as in Example 1 except that the temperature was raised to 3000 ° C. (graphitizing maximum temperature) at a heating rate of 5.0 ° C./min.
  • the graphite sheet after compression had a thickness of 21 ⁇ m and a density of 2.18 g / cm 3 .
  • Example 9 A graphite sheet of Example 9 was produced in the same manner as in Example 1 except that the polyimide film (A-5) was used instead of the polyimide film (A-1).
  • the graphite sheet after compression had a thickness of 25 ⁇ m and a density of 1.83 g / cm 3 .
  • Comparative Example 1 A graphite sheet of Comparative Example 1 was produced in the same manner as in Example 1 except that the polyimide film (A-6) was used instead of the polyimide film (A-1).
  • the compressed graphite sheet had a thickness of 22 ⁇ m and a density of 2.08 g / cm 3 .
  • Comparative Example 2 A graphite sheet of Comparative Example 2 was produced in the same manner as in Example 1 except that the polyimide film (A-7) was used instead of the polyimide film (A-1).
  • the compressed graphite sheet had a thickness of 22 ⁇ m and a density of 2.08 g / cm 3 .
  • Comparative Example 3 A graphite sheet of Comparative Example 3 was produced in the same manner as in Example 1 except that the temperature was raised to 2800 ° C. (graphitization maximum temperature) at a rate of temperature increase of 20 ° C./min.
  • the compressed graphite sheet had a thickness of 29 ⁇ m and a density of 1.58 g / cm 3 .
  • Comparative Example 4 A graphite sheet of Comparative Example 4 was produced in the same manner as in Example 1 except that the polyimide film (A-8) was used instead of the polyimide film (A-1).
  • the compressed graphite sheet had a thickness of 29 ⁇ m and a density of 1.58 g / cm 3 .
  • Comparative Example 5 A graphite sheet of Comparative Example 5 was produced in the same manner as in Example 1 except that the temperature was raised to 2400 ° C. (graphitization maximum temperature) at a temperature rising rate of 5.0 ° C./min.
  • the compressed graphite sheet had a thickness of 31 ⁇ m and a density of 1.47 g / cm 3 .
  • Table 1 shows the production conditions and physical properties of the graphite sheets of Examples 1 to 9 and Comparative Examples 1 to 5.
  • the graphite sheet obtained in the present invention can be suitably used as a heat radiating member for electronic equipment because it has good thermal diffusibility and flexibility, for example.

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Abstract

Provided are: a graphite sheet having favorable heat diffusion properties and flexibility; and a method for producing the same. This method for producing a graphite sheet containing 0.01 to 1.10 wt% of phosphorus includes: a carbonization step in which a polyimide film having a phosphate content within a prescribed range is carbonized to obtain a carbonaceous film; and a graphitizing step in which the carbonaceous film is subjected to a heat treatment at a prescribed temperature increase rate and a maximum temperature of at least 2,600°C.

Description

グラファイトシート及びその製造方法Graphite sheet and manufacturing method thereof
　本発明は、グラファイトシート及びその製造方法に関する。 The present invention relates to a graphite sheet and a manufacturing method thereof.
　グラファイトシートは、優れた放熱特性を有していることから、コンピュータなどの各種電子機器又は電気機器に搭載されている半導体素子、他の発熱部品などに放熱部品として用いられる。 Since graphite sheets have excellent heat dissipation properties, they are used as heat dissipation components in semiconductor devices and other heat generating components mounted on various electronic devices such as computers or electrical devices.
　このようなグラファイトシートは、ポリイミドフィルムを焼成して得ることができる。例えば、特許文献１には、無機粒子を含有したポリイミドフィルムを焼成してグラファイトシートを製造する技術が記載されている。 Such a graphite sheet can be obtained by baking a polyimide film. For example, Patent Document 1 describes a technique for producing a graphite sheet by baking a polyimide film containing inorganic particles.
特開２０１４－１３６７２１号公報JP 2014-136721 A
　従来、種々のグラファイトシートが知られているが、熱拡散性及び柔軟性が両立したグラファイトシートを得るためには、未だ改善の余地があった。 Conventionally, various graphite sheets are known, but there is still room for improvement in order to obtain a graphite sheet having both thermal diffusibility and flexibility.
　本発明の一態様は、熱拡散性及び柔軟性が良好なグラファイトシート及びその製造方法を提供することを目的とする。 An object of one embodiment of the present invention is to provide a graphite sheet having good thermal diffusibility and flexibility and a method for producing the same.
　本発明者らは、上記の課題を解決するために鋭意検討した結果、リンの含有量が所定の範囲内であるグラファイトシートにつき、熱拡散性及び柔軟性がともに優れることを見出し、本発明を完成させた。本発明は、以下を包含する。
〔１〕リンの含有量が０．０１重量％以上０．１０重量％以下であるグラファイトシート。
〔２〕リンの含有量が０．０１重量％以上０．１０重量％以下であるグラファイトシートの製造方法であり、
　リン酸塩の含有量が０．０１重量％以上０．４９重量％以下であるポリイミドフィルムを炭化して炭素質フィルムを得る炭化工程、及び、
　前記炭素質フィルムを、昇温速度を０．０１℃／ｍｉｎ以上２０℃／ｍｉｎ未満とし、最高温度を２６００℃以上で熱処理してグラファイトシートを得る黒鉛化工程、
を含むグラファイトシートの製造方法。 As a result of intensive studies to solve the above problems, the present inventors have found that the graphite sheet having a phosphorus content within a predetermined range is excellent in both thermal diffusibility and flexibility, and Completed. The present invention includes the following.
[1] A graphite sheet having a phosphorus content of 0.01 wt% or more and 0.10 wt% or less.
[2] A method for producing a graphite sheet, wherein the phosphorus content is 0.01 wt% or more and 0.10 wt% or less,
A carbonization step of carbonizing a polyimide film having a phosphate content of 0.01 wt% or more and 0.49 wt% or less to obtain a carbonaceous film; and
A graphitization step of obtaining a graphite sheet by heat-treating the carbonaceous film at a heating rate of 0.01 ° C./min to less than 20 ° C./min and a maximum temperature of 2600 ° C. or more;
The manufacturing method of the graphite sheet containing this.
　本発明の一態様によれば、熱拡散性及び柔軟性が良好なグラファイトシートを得ることができる。 According to one embodiment of the present invention, a graphite sheet with good thermal diffusivity and flexibility can be obtained.
　本発明の一実施形態について以下に説明するが、本発明はこれに限定されるものではない。本発明は、以下に説明する各構成に限定されるものではなく、特許請求の範囲に示した範囲で種々の変更が可能であり、異なる実施形態や実施例にそれぞれ開示された技術的手段を適宜組み合わせて得られる実施形態や実施例についても本発明の技術的範囲に含まれる。また、本明細書中に記載された学術文献及び特許文献の全てが、本明細書中において参考文献として援用される。また、本明細書において特記しない限り、数値範囲を表す「Ａ～Ｂ」は、「Ａ以上Ｂ以下」を意図する。 One embodiment of the present invention will be described below, but the present invention is not limited to this. The present invention is not limited to each configuration described below, and various modifications can be made within the scope shown in the claims, and technical means disclosed in different embodiments and examples respectively. Embodiments and examples obtained by appropriately combining them are also included in the technical scope of the present invention. Moreover, all the academic literatures and patent literatures described in this specification are used as references in this specification. Unless otherwise specified in this specification, “A to B” indicating a numerical range is intended to be “A or more and B or less”.
　＜１．グラファイトシートの製造方法＞
　本発明の一態様のグラファイトシートの製造方法は、リンの含有量が０．０１重量％以上０．１０重量％以下であるグラファイトシートの製造方法であり、リン酸塩の含有量が０．０１重量％以上０．４９重量％以下であるポリイミドフィルムを炭化して炭素質フィルムを得る炭化工程、及び、前記炭素質フィルムを、昇温速度を０．０１℃／ｍｉｎ以上２０℃／ｍｉｎ未満とし、最高温度を２６００℃以上で熱処理してグラファイトシートを得る黒鉛化工程、を含むものであればよい。 <1. Manufacturing method of graphite sheet>
The method for producing a graphite sheet of one embodiment of the present invention is a method for producing a graphite sheet having a phosphorus content of 0.01 wt% or more and 0.10 wt% or less, and a phosphate content of 0.01 wt%. A carbonization step of carbonizing a polyimide film having a weight percent of not less than 0.49 wt% to obtain a carbonaceous film, and a heating rate of the carbonaceous film not less than 0.01 ° C / min and less than 20 ° C / min. And a graphitization step of obtaining a graphite sheet by heat treatment at a maximum temperature of 2600 ° C. or higher.
　本製造方法は、ポリイミドフィルムを不活性ガス雰囲気下や減圧下で熱処理する、いわゆる高分子熱分解法である。具体的には、ポリイミドフィルムを１０００℃程度の温度まで予備加熱し、炭素質フィルムを得る炭化工程と、炭化工程で作製された炭素質フィルムを２６００℃以上の温度まで加熱し、グラファイト化する黒鉛化工程と、これを圧縮する圧縮工程とを経て、グラファイトシートが得られる。なお、炭化工程と黒鉛化工程とは連続して行っても、炭化工程を終了させて、その後黒鉛化工程のみを単独で行っても構わない。また、本発明の一実施形態のグラファイトシートの製造方法において、圧縮工程は行っても、行わなくてもよい。 This manufacturing method is a so-called polymer pyrolysis method in which a polyimide film is heat-treated in an inert gas atmosphere or under reduced pressure. Specifically, the graphite film is preheated to a temperature of about 1000 ° C. to obtain a carbonaceous film, and the carbonaceous film produced in the carbonization step is heated to a temperature of 2600 ° C. or more to graphitize. A graphite sheet is obtained through the conversion step and the compression step of compressing the same. Note that the carbonization step and the graphitization step may be performed continuously, or the carbonization step may be terminated, and then only the graphitization step may be performed alone. Moreover, in the manufacturing method of the graphite sheet of one Embodiment of this invention, it does not need to perform a compression process.
　（炭化工程）
　炭化工程は、ポリイミドフィルムを１０００℃程度の温度まで熱処理し、ポリイミドフィルムを炭素化する工程である。例えば、最高温度は、７００℃～１８００℃であることが好ましく、８００℃～１５００℃であることがより好ましく、９００℃～１２００℃であることがさらに好ましく、１０００℃であることが特に好ましい。 (Carbonization process)
A carbonization process is a process of heat-processing a polyimide film to the temperature of about 1000 degreeC, and carbonizing a polyimide film. For example, the maximum temperature is preferably 700 ° C. to 1800 ° C., more preferably 800 ° C. to 1500 ° C., further preferably 900 ° C. to 1200 ° C., and particularly preferably 1000 ° C.
　炭化工程における昇温速度は、０．０１℃／ｍｉｎ以上２０℃／ｍｉｎ未満であることが好ましく、０．１℃／ｍｉｎ～１０℃／ｍｉｎであることがより好ましく、０．５℃／ｍｉｎ～５．０℃／ｍｉｎ未満であることがさらに好ましい。昇温速度が前記の範囲内であれば、ポリイミドフィルム中のリンが好ましい程度残存し、熱拡散性及び柔軟性が良好なグラファイトシートを得ることができる。 The heating rate in the carbonization step is preferably 0.01 ° C./min or more and less than 20 ° C./min, more preferably 0.1 ° C./min to 10 ° C./min, and 0.5 ° C./min. More preferably, it is less than ˜5.0 ° C./min. If the rate of temperature increase is within the above range, a preferable amount of phosphorus in the polyimide film remains, and a graphite sheet having good thermal diffusibility and flexibility can be obtained.
　炭化工程での保持時間（具体的には、炭化最高温度での保持時間）は、１分～１時間であることが好ましく、５分～３０分であることがより好ましく、８分～１５分であることがさらに好ましい。保持時間が前記の範囲内であれば、ポリイミドフィルム中のリンが好ましい程度残存し、熱拡散性及び柔軟性が良好なグラファイトシートを得ることができる。 The holding time in the carbonization step (specifically, the holding time at the maximum carbonization temperature) is preferably 1 minute to 1 hour, more preferably 5 minutes to 30 minutes, and 8 minutes to 15 minutes. More preferably. If the holding time is within the above range, a preferable amount of phosphorus in the polyimide film remains, and a graphite sheet having good thermal diffusibility and flexibility can be obtained.
　炭化工程では、長方形状のポリイミドフィルムを積層した積層ポリイミドフィルムを炭化してもよく、ロール状のポリイミドフィルムをロール状のまま炭化してもよく、ロール状ポリイミドフィルムからフィルムを繰り出して炭化してもよい。 In the carbonization step, the laminated polyimide film obtained by laminating the rectangular polyimide film may be carbonized, the roll-shaped polyimide film may be carbonized while being in a roll shape, and the film is drawn out from the roll-shaped polyimide film and carbonized. Also good.
　（黒鉛化工程）
　黒鉛化工程は、炭化工程で得た炭素質フィルムを２６００℃以上の温度まで熱処理し、炭素質フィルムを黒鉛化する工程である。例えば、最高温度は、２６００℃以上、２７００℃以上、２８００℃以上、２９００℃以上、又は３０００℃以上を好ましく例示できる。上限は特に限定されないが、３３００℃以下であることが好ましく、３２００℃以下であることがより好ましい。なお、黒鉛化工程は、減圧下もしくは不活性ガス中でおこなわれるが、不活性ガスとしてはアルゴン、または、ヘリウムが適当である。 (Graphitization process)
The graphitization step is a step of heat-treating the carbonaceous film obtained in the carbonization step to a temperature of 2600 ° C. or higher to graphitize the carbonaceous film. For example, the maximum temperature is preferably 2600 ° C or higher, 2700 ° C or higher, 2800 ° C or higher, 2900 ° C or higher, or 3000 ° C or higher. Although an upper limit is not specifically limited, It is preferable that it is 3300 degrees C or less, and it is more preferable that it is 3200 degrees C or less. The graphitization step is performed under reduced pressure or in an inert gas. Argon or helium is suitable as the inert gas.
　黒鉛化工程における昇温速度は、例えば、０．０１℃／ｍｉｎ以上２０℃／ｍｉｎ未満、０．１℃／ｍｉｎ～１０℃／ｍｉｎ、０．２℃／ｍｉｎ～５．０℃／ｍｉｎ、０．５℃／ｍｉｎ～２．０℃／ｍｉｎを好ましく例示できる。昇温速度が前記の範囲内であれば、ポリイミドフィルム中のリンが好ましい程度残存し、熱拡散性及び柔軟性が良好なグラファイトシートを得ることができる。 The heating rate in the graphitization step is, for example, 0.01 ° C./min or more and less than 20 ° C./min, 0.1 ° C./min to 10 ° C./min, 0.2 ° C./min to 5.0 ° C./min, A preferable example is 0.5 ° C./min to 2.0 ° C./min. If the rate of temperature increase is within the above range, a preferable amount of phosphorus in the polyimide film remains, and a graphite sheet having good thermal diffusibility and flexibility can be obtained.
　黒鉛化工程での保持時間（具体的には、黒鉛化最高温度での保持時間）は、１分～１時間であることが好ましく、５分～３０分であることがより好ましく、８分～１５分であることがさらに好ましい。保持時間が前記の範囲内であれば、ポリイミドフィルム中のリンが好ましい程度残存し、熱拡散性及び柔軟性が良好なグラファイトシートを得ることができる。 The retention time in the graphitization step (specifically, the retention time at the maximum graphitization temperature) is preferably 1 minute to 1 hour, more preferably 5 minutes to 30 minutes, and more preferably 8 minutes to More preferably, it is 15 minutes. If the holding time is within the above range, a preferable amount of phosphorus in the polyimide film remains, and a graphite sheet having good thermal diffusibility and flexibility can be obtained.
　黒鉛化工程では、長方形状の炭化フィルムを積層した積層炭化フィルムを黒鉛化してもよく、ロール状の炭化フィルムをロール状のまま黒鉛化してもよく、ロール状の炭化フィルムからフィルムを繰り出して黒鉛化してもよい。 In the graphitization step, a laminated carbonized film in which rectangular carbonized films are laminated may be graphitized, or a roll-shaped carbonized film may be graphitized while being in a roll shape. May be used.
　（圧縮工程）
　黒鉛化後の炭素質フィルムに圧縮工程を施してもよい。圧縮工程を施すことによって、得られるグラファイトシートに柔軟性を付与することができる。圧縮工程は、面状に圧縮する方法や、金属ロールなどを用いて圧延する方法などを用いることができる。圧縮工程は室温で行っても、黒鉛化工程中に行ってもかまわない。 (Compression process)
You may give a compression process to the carbonaceous film after graphitization. By performing the compression step, flexibility can be imparted to the obtained graphite sheet. For the compression step, a method of compressing in a planar shape, a method of rolling using a metal roll or the like can be used. The compression step may be performed at room temperature or during the graphitization step.
　＜２．グラファイトシート＞
　グラファイトシートは、リンの含有量が０．０１重量％～０．１０重量％であり、０．０２重量％～０．０８重量％であることがより好ましい。かかる範囲内であれば、グラファイトシートにおいて、熱拡散性及び柔軟性の双方の物性が優れる。 <2. Graphite sheet>
The graphite sheet has a phosphorus content of 0.01 wt% to 0.10 wt%, more preferably 0.02 wt% to 0.08 wt%. Within such a range, the physical properties of both thermal diffusibility and flexibility are excellent in the graphite sheet.
　また、グラファイトシートの熱拡散率は、７．０ｃｍ２／ｓ以上であることが好ましく、７．３ｃｍ２／ｓ以上であることがより好ましく、８．０ｃｍ２／ｓ以上であることがさらに好ましい。 The thermal diffusivity of the graphite sheet is preferably 7.0 cm 2 / s or more, more preferably 7.3 cm 2 / s or more, further preferably 8.0 cm 2 / s or more .
　また、グラファイトシートの柔軟性は、後述する実施例の柔軟性評価において、「Ｃ」以上であることが好ましく、「Ｂ」以上であることがより好ましく、「Ａ」以上であることがさらに好ましい。 Further, the flexibility of the graphite sheet is preferably “C” or more, more preferably “B” or more, and further preferably “A” or more in the flexibility evaluation of Examples described later. .
　また、グラファイトシートの厚みは、５μｍ～６０μｍであることが好ましく、１０μｍ～５０μｍであることがより好ましく、１５μｍ～４０μｍであることがさらに好ましい。 The thickness of the graphite sheet is preferably 5 μm to 60 μm, more preferably 10 μm to 50 μm, and further preferably 15 μm to 40 μm.
　グラファイトシートの密度は、１．０ｇ／ｃｍ３～２．２６ｇ／ｃｍ３が好ましく、１．３ｇ／ｃｍ３～２．２ｇ／ｃｍ３であることがより好ましく、１．６ｇ／ｃｍ３～２．１８ｇ／ｃｍ３であることがさらに好ましい。 The density of the graphite sheet is preferably from 1.0g / cm 3 ~ 2.26g / cm 3, more preferably from 1.3g / cm 3 ~ 2.2g / cm 3, 1.6g / cm 3 ~ 2 More preferably, it is 18 g / cm 3 .
　＜３．グラファイトシート用のポリイミドフィルム＞
　以下、本発明の一実施形態に使用し得るポリイミドフィルムについて詳説する。前記製造方法に用いられるグラファイトシート用のポリイミドフィルムは、酸二無水物成分と、ジアミン成分とを原料とするポリイミドフィルムであり、所定量のリン酸塩を含有するものである。 <3. Polyimide film for graphite sheets>
Hereinafter, a polyimide film that can be used in one embodiment of the present invention will be described in detail. The polyimide film for a graphite sheet used in the manufacturing method is a polyimide film using an acid dianhydride component and a diamine component as raw materials, and contains a predetermined amount of phosphate.
　（リン酸塩）
　ポリイミドフィルムは、リン酸塩の含有量が０．０１重量％～０．４９重量％であることが好ましく、０．１０重量％～０．４０重量％であることがより好ましく、０．１２重量％～０．３５重量％であることがさらに好ましい。かかる範囲内であれば、最終的に得られるグラファイトシートの熱拡散性及び柔軟性の両方の物性が優れる。 (Phosphate)
The polyimide film preferably has a phosphate content of 0.01% to 0.49% by weight, more preferably 0.10% to 0.40% by weight, and 0.12% by weight. More preferably, the content is from 0.3 to 0.35% by weight. Within such a range, the physical properties of both the thermal diffusibility and flexibility of the finally obtained graphite sheet are excellent.
　本発明の一実施形態において使用可能なリン酸塩としては、ＣａＨＰＯ４、（ＮＨ４）２ＨＰＯ４などを挙げることができる。なかでもＣａＨＰＯ４及び（ＮＨ４）２ＨＰＯ４は、ポリイミドフィルム内部から昇華するときに発生するガスにより良好な膨れが生じ、熱伝導性に優れた良好なグラファイトが得られるため、好ましく使用し得る。リン酸塩は、無機粒子（すなわち、フィラー）としてポリイミドフィルムに添加することができる。 Examples of the phosphate that can be used in the embodiment of the present invention include CaHPO 4 , (NH 4 ) 2 HPO 4, and the like. Among them, CaHPO 4 and (NH 4 ) 2 HPO 4 can be preferably used because good swelling occurs due to gas generated when sublimating from the inside of the polyimide film, and good graphite having excellent thermal conductivity is obtained. . Phosphate can be added to the polyimide film as inorganic particles (ie, filler).
　（酸二無水物成分）
　使用し得る酸二無水物成分は、ピロメリット酸二無水物、２，３，６，７，－ナフタレンテトラカルボン酸二無水物、３，３’，４，４’－ビフェニルテトラカルボン酸二無水物、１，２，５，６－ナフタレンテトラカルボン酸二無水物、２，２’，３，３’－ビフェニルテトラカルボン酸二無水物、３，３’，４，４’－ベンゾフェノンテトラカルボン酸二無水物、２，２－ビス（３，４－ジカルボキシフェニル）プロパン二無水物、３，４，９，１０－ペリレンテトラカルボン酸二無水物、１，１－（３，４－ジカルボキシフェニル）エタン二無水物、１，１－ビス（２，３－ジカルボキシフェニル）エタン二無水物、１，１－ビス（３，４－ジカルボキシフェニル）エタン二無水物、ビス（２，３－ジカルボキシフェニル）メタン二無水物、ビス（３，４－ジカルボキシフェニル）メタン二無水物、オキシジフタル酸二無水物、ビス（３，４－ジカルボキシフェニル）スルホン二無水物、ｐ－フェニレンビス（トリメリット酸モノエステル酸無水物）、エチレンビス（トリメリット酸モノエステル酸無水物）、ビスフェノールＡビス（トリメリット酸モノエステル酸無水物）及びそれらの類似物を挙げることができる。これらを任意の割合で混合することができる。なかでも、ピロメリット酸二無水物や３，３’，４，４’－ビフェニルテトラカルボン酸二無水物を使用することが好ましい。かかる酸二無水物成分を使用することにより、最終的に得られるグラファイトシートの物性が良好なものとなる。 (Acid dianhydride component)
The acid dianhydride components that can be used are pyromellitic dianhydride, 2,3,6,7, -naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid Dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 1,1- (3,4-dicarboxy Phenyl) ethane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, bis (2,3 -Dicarboxyphenyl) methane dianhydride, bi (3,4-dicarboxyphenyl) methane dianhydride, oxydiphthalic dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, p-phenylenebis (trimellitic acid monoester acid anhydride), Mention may be made of ethylene bis (trimellitic acid monoester acid anhydride), bisphenol A bis (trimellitic acid monoester acid anhydride) and the like. These can be mixed in an arbitrary ratio. Of these, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride are preferably used. By using such an acid dianhydride component, the physical properties of the finally obtained graphite sheet are improved.
　（ジアミン成分）
　使用し得るジアミン成分は、４，４’－ジアミノジフェニルエーテル、ｐ－フェニレンジアミン、４，４’－ジアミノジフェニルメタン、ベンジジン、３，３’－ジクロロベンジジン、４，４’－ジアミノジフェニルスルフィド、３，３’－ジアミノジフェニルスルホン、４，４’－ジアミノジフェニルスルホン、３，３’－ジアミノジフェニルエーテル、３，４’－ジアミノジフェニルエーテル、１，５－ジアミノナフタレン、４，４’－ジアミノジフェニルジエチルシラン、４，４’－ジアミノジフェニルシラン、４，４’－ジアミノジフェニルエチルホスフィンオキシド、４，４’－ジアミノジフェニルＮ－メチルアミン、４，４’－ジアミノジフェニルＮ－フェニルアミン、１，３－ジアミノベンゼン、１，２－ジアミノベンゼン及びそれらの類似物を挙げることができる。これらを任意の割合で混合することができる。なかでも、４，４’－ジアミノジフェニルエーテルやｐ－フェニレンジアミンを使用することが好ましい。かかるジアミン成分を使用することにより、最終的に得られるグラファイトシートの物性が良好なものとなる。 (Diamine component)
The diamine components that can be used are 4,4′-diaminodiphenyl ether, p-phenylenediamine, 4,4′-diaminodiphenylmethane, benzidine, 3,3′-dichlorobenzidine, 4,4′-diaminodiphenyl sulfide, 3,3 '-Diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 4,4'-diaminodiphenyldiethylsilane, 4, 4'-diaminodiphenylsilane, 4,4'-diaminodiphenylethylphosphine oxide, 4,4'-diaminodiphenyl N-methylamine, 4,4'-diaminodiphenyl N-phenylamine, 1,3-diaminobenzene, 1 , 2-diaminobenzene and the like Can be mentioned. These can be mixed in an arbitrary ratio. Of these, 4,4′-diaminodiphenyl ether and p-phenylenediamine are preferably used. By using such a diamine component, the physical properties of the finally obtained graphite sheet are improved.
　（ポリイミドフィルムの厚み）
　ポリイミドフィルムの厚みは、１２．５μｍ～１２５μｍ、好ましくは２５μｍ～１００μｍ、より好ましくは３５μｍ～７５μｍである。前記範囲内であれば、厚み方向に均一に熱処理されるため、熱拡散性が向上する。 (Polyimide film thickness)
The thickness of the polyimide film is 12.5 μm to 125 μm, preferably 25 μm to 100 μm, more preferably 35 μm to 75 μm. If it is in the said range, since it heat-processes uniformly in the thickness direction, thermal diffusivity improves.
　（イミド化方法）
　ポリイミドのイミド化方法には、前駆体であるポリアミド酸を加熱してイミド転化する熱キュア法、または、無水酢酸等の酸無水物に代表される脱水剤や、ピコリン、キノリン、イソキノリン、ピリジン等の第３級アミン類に代表されるイミド化促進剤を用いて、前駆体であるポリアミド酸をイミド転化するケミカルキュア法、のいずれを用いてもよい。ケミカルキュア法を用いる場合のイミド化促進剤としては、上で挙げた第３級アミン類が好ましい。 (Imidation method)
The polyimide imidization method includes a thermal curing method in which the precursor polyamic acid is heated to convert to imide, or a dehydrating agent typified by an acid anhydride such as acetic anhydride, picoline, quinoline, isoquinoline, pyridine, etc. Any of the chemical curing methods for converting the polyamic acid, which is a precursor, into an imide, using an imidization accelerator typified by the above tertiary amines may be used. As the imidization accelerator in the case of using the chemical cure method, the tertiary amines listed above are preferable.
　特に、得られるポリイミドフィルムの線膨張係数が小さく、弾性率が高く、複屈折が大きくなりやすく、また比較的低温で迅速なグラファイト化が可能で、品質のよいグラファイトシートを得ることができるという観点から、ケミカルキュア法の方が好ましい。特に、脱水剤とイミド化促進剤とを併用することは、得られるポリイミドフィルムの線膨張係数が小さく、弾性率が大きく、複屈折が大きくなり得るので好ましい。また、ケミカルキュア法は、イミド化反応がより速く進行するので、加熱処理においてイミド化反応を短時間で完結させることができ、生産性に優れた工業的に有利な方法である。 In particular, the polyimide film obtained has a low linear expansion coefficient, high modulus of elasticity, high birefringence, and can be rapidly graphitized at a relatively low temperature to obtain a quality graphite sheet. Therefore, the chemical cure method is preferred. In particular, the combined use of a dehydrating agent and an imidization accelerator is preferable because the resulting polyimide film has a small linear expansion coefficient, a large elastic modulus, and a large birefringence. In addition, the chemical cure method is an industrially advantageous method that can complete the imidization reaction in a short time in the heat treatment because the imidization reaction proceeds faster, and is excellent in productivity.
　（ポリアミド酸の製造方法）
　ポリアミド酸の製造方法としては特に制限されないが、例えば、芳香族酸二無水物とジアミンとを実質的に等モル量で有機溶媒中に溶解し、この有機溶液を芳香族酸二無水物とジアミンとの重合が完了するまで制御された温度条件下で攪拌することによってポリアミド酸が製造され得る。重合方法としては特に制限されないが、例えば次のような重合方法（１）－（５）のいずれかが好ましい。なお、（１）－（５）では、芳香族酸二無水物として芳香族テトラカルボン酸二無水物を、ジアミンとして芳香族ジアミン化合物を用いた場合を例示している。 (Method for producing polyamic acid)
The method for producing the polyamic acid is not particularly limited. For example, the aromatic acid dianhydride and the diamine are dissolved in an organic solvent in a substantially equimolar amount, and the organic solution is dissolved in the aromatic acid dianhydride and the diamine. The polyamic acid can be prepared by stirring under controlled temperature conditions until the polymerization with is complete. The polymerization method is not particularly limited, but for example, any of the following polymerization methods (1) to (5) is preferable. Note that (1) to (5) exemplify cases where an aromatic tetracarboxylic dianhydride is used as the aromatic dianhydride and an aromatic diamine compound is used as the diamine.
　（１）芳香族ジアミン化合物を有機極性溶媒中に溶解し、芳香族ジアミン化合物と、これと実質的に等モルの芳香族テトラカルボン酸二無水物とを反応させて重合する方法。 (1) A method of polymerizing by dissolving an aromatic diamine compound in an organic polar solvent and reacting the aromatic diamine compound with a substantially equimolar amount of an aromatic tetracarboxylic dianhydride.
　（２）芳香族テトラカルボン酸二無水物と、これに対して過小モル量の芳香族ジアミン化合物とを有機極性溶媒中で反応させ、両末端に酸無水物基を有するプレポリマを得る。続いて、このプレポリマに、芳香族テトラカルボン酸二無水物に対して実質的に等モルである芳香族ジアミン化合物を重合させる方法。 (2) An aromatic tetracarboxylic dianhydride is reacted with a small molar amount of an aromatic diamine compound in an organic polar solvent to obtain a prepolymer having acid anhydride groups at both ends. Subsequently, a method of polymerizing the prepolymer with an aromatic diamine compound that is substantially equimolar with respect to the aromatic tetracarboxylic dianhydride.
　上記（２）の方法の具体例は、ジアミンと酸二無水物とを用いて前記酸二無水物を両末端に有するプレポリマを合成し、前記プレポリマに、前記プレポリマの合成に使用したジアミンと同種のジアミンまたは異なる種類のジアミンを反応させてポリアミド酸を合成する方法と同様である。（２）の方法においても、プレポリマと反応させる芳香族ジアミン化合物は、前記プレポリマの合成に使用した芳香族ジアミン化合物と同種の芳香族ジアミン化合物または異なる種類の芳香族ジアミン化合物であってもよい。 A specific example of the method (2) is that a prepolymer having the acid dianhydride at both ends is synthesized using a diamine and an acid dianhydride, and the same kind of diamine used for the synthesis of the prepolymer is used for the prepolymer. This method is the same as the method of synthesizing polyamic acid by reacting diamines of different types or different types of diamines. Also in the method (2), the aromatic diamine compound to be reacted with the prepolymer may be the same kind of aromatic diamine compound as the aromatic diamine compound used for the synthesis of the prepolymer or a different kind of aromatic diamine compound.
　（３）芳香族テトラカルボン酸二無水物と、これに対し過剰モル量の芳香族ジアミン化合物とを有機極性溶媒中で反応させ、両末端にアミノ基を有するプレポリマを得る。続いて、このプレポリマに芳香族ジアミン化合物を追加添加後に、芳香族テトラカルボン酸二無水物と芳香族ジアミン化合物とが実質的に等モルとなるように、プレポリマと芳香族テトラカルボン酸二無水物とを重合する方法。 (3) An aromatic tetracarboxylic dianhydride is reacted with an excess molar amount of an aromatic diamine compound in an organic polar solvent to obtain a prepolymer having amino groups at both ends. Subsequently, after the addition of an aromatic diamine compound to the prepolymer, the prepolymer and the aromatic tetracarboxylic dianhydride so that the aromatic tetracarboxylic dianhydride and the aromatic diamine compound are substantially equimolar. And the method of polymerizing.
　（４）芳香族テトラカルボン酸二無水物を有機極性溶媒中に溶解および／または分散させた後に、その酸二無水物に対して実質的に等モルになるように芳香族ジアミン化合物を加えて、芳香族テトラカルボン酸二無水物と芳香族ジアミン化合物とを重合させる方法。 (4) After the aromatic tetracarboxylic dianhydride is dissolved and / or dispersed in an organic polar solvent, an aromatic diamine compound is added so as to be substantially equimolar with respect to the acid dianhydride. A method of polymerizing an aromatic tetracarboxylic dianhydride and an aromatic diamine compound.
　（５）実質的に等モルの芳香族テトラカルボン酸二無水物と芳香族ジアミン化合物との混合物を、有機極性溶媒中で反応させて重合する方法。 (5) A method in which a mixture of substantially equimolar aromatic tetracarboxylic dianhydride and aromatic diamine compound is reacted in an organic polar solvent for polymerization.
　なお、本発明は、以下のような構成とすることも可能である。
〔１〕リンの含有量が０．０１重量％以上０．１０重量％以下であるグラファイトシート。
〔２〕リンの含有量が０．０２重量％以上０．０８重量％以下である〔１〕に記載のグラファイトシート。
〔３〕リンの含有量が０．０１重量％以上０．１０重量％以下であるグラファイトシートの製造方法であり、
　リン酸塩の含有量が０．０１重量％以上０．４９重量％以下であるポリイミドフィルムを炭化して炭素質フィルムを得る炭化工程、及び、
　前記炭素質フィルムを、昇温速度を０．０１℃／ｍｉｎ以上２０℃／ｍｉｎ未満とし、最高温度を２６００℃以上で熱処理してグラファイトシートを得る黒鉛化工程、
を含むグラファイトシートの製造方法。 The present invention can be configured as follows.
[1] A graphite sheet having a phosphorus content of 0.01 wt% or more and 0.10 wt% or less.
[2] The graphite sheet according to [1], wherein the phosphorus content is 0.02 wt% or more and 0.08 wt% or less.
[3] A method for producing a graphite sheet, wherein the phosphorus content is 0.01 wt% or more and 0.10 wt% or less,
A carbonization step of carbonizing a polyimide film having a phosphate content of 0.01 wt% or more and 0.49 wt% or less to obtain a carbonaceous film; and
A graphitization step of obtaining a graphite sheet by heat-treating the carbonaceous film at a heating rate of 0.01 ° C./min to less than 20 ° C./min and a maximum temperature of 2600 ° C. or more;
The manufacturing method of the graphite sheet containing this.
　以下、実施例により本発明をさらに詳細に説明するが、本発明は下記実施例のみに限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.
　＜ポリイミドフィルムのリンの含有量＞
　ポリイミドフィルムのリンの含有量を、用いたリン酸塩の分子量とリンの原子量との比から計算して求めた。 <Phosphorus content of polyimide film>
The phosphorus content of the polyimide film was calculated from the ratio between the molecular weight of the phosphate used and the atomic weight of phosphorus.
　＜グラファイトシートのリンの含有量＞
　グラファイトシートのリンの含有量は、蛍光Ｘ線分析装置を用いて、測定対象のグラファイトフィルムのリンのピークと、リン濃度既知の物質のリンのピークとの比で求めた。また、蛍光Ｘ線分析装置として、株式会社リガク製のＺＳＸ　ＰｒｉｍｕｓＩＩを用い、リン濃度既知の物質として、リン濃度０．０３４重量％のポリイミドフィルムを用いて測定した。 <Phosphorus content of graphite sheet>
The phosphorus content of the graphite sheet was determined by the ratio of the phosphorus peak of the graphite film to be measured and the phosphorus peak of a substance having a known phosphorus concentration, using an X-ray fluorescence analyzer. Further, ZSX Primus II manufactured by Rigaku Corporation was used as a fluorescent X-ray analyzer, and a polyimide film having a phosphorus concentration of 0.034% by weight was used as a substance having a known phosphorus concentration.
　＜ＭＩＴ耐屈曲試験における折り曲げ回数の測定（柔軟性評価）＞
　後述の方法で得られたグラファイトシートのＭＩＴ耐屈曲試験における折り曲げ回数を測定し、柔軟性の評価方法とした。試験方法について、以下に示す。ＭＩＴ耐屈曲試験では、東洋精機（株）社製ＭＩＴ耐揉疲労試験機型式Ｄを用いた。試験条件は、Ｒ＝２ｍｍ、左右の折り曲げ角度：１３５°、スプリング：φ１４ｍｍとした。 <Measurement of the number of bendings in the MIT bending test (flexibility evaluation)>
The number of bendings in the MIT bending resistance test of the graphite sheet obtained by the method described later was measured, and this was used as a method for evaluating flexibility. The test method is shown below. In the MIT bending resistance test, an MIT fatigue resistance tester model D manufactured by Toyo Seiki Co., Ltd. was used. The test conditions were R = 2 mm, left and right bending angles: 135 °, and spring: φ14 mm.
　耐屈曲試験における折り曲げ回数（ＭＩＴ）は、回数が多いほど、グラファイトシートが柔軟であり、耐屈曲性に優れていることを意味する。そのためＭＩＴの回数が多いグラファイトシートを屈曲部分に使用しても破壊されにくくなる。 The number of bendings (MIT) in the bending resistance test means that the larger the number, the more flexible the graphite sheet and the better the bending resistance. Therefore, even if a graphite sheet having a large number of MITs is used for the bent portion, it is difficult to break.
　なお、評価基準は以下のとおりとした。
Ａ：折り曲げ回数が１０００００回以上
Ｂ：折り曲げ回数が１００００回以上１０００００回未満
Ｃ：折り曲げ回数が１０００回以上１００００回未満
Ｄ：折り曲げ回数が１００回以上１０００回未満
Ｅ：折り曲げ回数が１００回未満
　＜熱拡散性＞
　後述の方法で得られたグラファイトシートの熱拡散率を以下の方法で測定した。具体的には、光交流法に基づく熱拡散率測定装置（アルバック理工（株）社の「ＬａｓｅｒＰｉｔ」）を用い、４ｍｍ×４０ｍｍの形状に切り取られたグラファイトシートのサンプルについて、２０℃の雰囲気下で１０Ｈｚの交流条件下で測定した。 The evaluation criteria were as follows.
A: Number of folding times is 100,000 or more B: Number of folding times is 10,000 or more and less than 100,000 times C: Number of folding times is 1000 or more and less than 10,000 times D: Number of folding times is 100 times or more and less than 1000 times E: Number of folding times is less than 100 times < Thermal diffusivity>
The thermal diffusivity of the graphite sheet obtained by the method described later was measured by the following method. Specifically, a graphite sheet sample cut into a 4 mm × 40 mm shape using a thermal diffusivity measuring apparatus (“LaserPit” manufactured by ULVAC-RIKO Co., Ltd.) based on the optical alternating current method is used in an atmosphere of 20 ° C. And measured under AC conditions of 10 Hz.
　＜ポリイミドフィルムの作製方法＞
　（製造例１）
　４，４’－ジアミノジフェニルエーテル（ＯＤＡ）を溶解したジメチルホルムアミド溶液に、ピロメリット酸二無水物（ＰＭＤＡ）を、ＯＤＡとＰＭＤＡとが当モル量となるように溶解して、ポリアミド酸を１８．５重量％含むポリアミド酸溶液を得た。得られたポリアミド酸溶液に、リン酸水素カルシウムの濃度がポリアミド酸の固形分に対して０．１５重量％となるようにリン酸水素カルシウムを添加した。この溶液を冷却しながら、ポリアミド酸に含まれるカルボン酸基に対して、１当量の無水酢酸、１当量のイソキノリン、およびジメチルホルムアミドを含むイミド化触媒を添加し脱泡した。次にこの混合溶液が、乾燥後に厚さ５０μｍになるようにアルミ箔上に塗布し、混合溶液層を得た。アルミ箔上の混合溶液層は、熱風オーブン及び遠赤外線ヒーターを用いて乾燥した。 <Preparation method of polyimide film>
(Production Example 1)
In a dimethylformamide solution in which 4,4′-diaminodiphenyl ether (ODA) is dissolved, pyromellitic dianhydride (PMDA) is dissolved so that ODA and PMDA are in an equimolar amount, and the polyamic acid is 18. A polyamic acid solution containing 5% by weight was obtained. To the obtained polyamic acid solution, calcium hydrogen phosphate was added so that the concentration of calcium hydrogen phosphate was 0.15% by weight based on the solid content of the polyamic acid. While this solution was cooled, an imidization catalyst containing 1 equivalent of acetic anhydride, 1 equivalent of isoquinoline, and dimethylformamide was added to the carboxylic acid group contained in the polyamic acid to degas. Next, this mixed solution was applied on an aluminum foil so as to have a thickness of 50 μm after drying to obtain a mixed solution layer. The mixed solution layer on the aluminum foil was dried using a hot air oven and a far infrared heater.
　乾燥条件は以下のとおりである。まず、アルミ箔上の混合溶液層を、熱風オーブンで１２０℃において２４０秒乾燥して、自己支持性を有するゲルフィルムにした。そのゲルフィルムをアルミ箔から引き剥がし、フレームに固定した。さらに、ゲルフィルムを、熱風オーブンにて１２０℃で３０秒、２７５℃で４０秒、４００℃で４２秒、４５０℃で５０秒、および遠赤外線ヒーターにて４６０℃で２２秒と段階的に加熱して乾燥した。以上のようにして、リンの含有量０．０３４重量％、厚さ５０μｍのポリイミドフィルム（Ａ－１）を作製した。 Drying conditions are as follows. First, the mixed solution layer on the aluminum foil was dried in a hot air oven at 120 ° C. for 240 seconds to form a self-supporting gel film. The gel film was peeled off from the aluminum foil and fixed to the frame. Furthermore, the gel film is heated stepwise in a hot air oven at 120 ° C. for 30 seconds, 275 ° C. for 40 seconds, 400 ° C. for 42 seconds, 450 ° C. for 50 seconds, and a far infrared heater at 460 ° C. for 22 seconds. And dried. As described above, a polyimide film (A-1) having a phosphorus content of 0.034% by weight and a thickness of 50 μm was produced.
　（製造例２）
　得られたポリアミド酸溶液に、リン酸水素カルシウムの濃度がポリアミド酸の固形分に対して０．０５重量％となるようにリン酸水素カルシウムを添加した以外は、製造例１と同様にして、リンの含有量０．０１１重量％、厚さ５０μｍのポリイミドフィルム（Ａ－２）を作製した。 (Production Example 2)
Except that calcium hydrogen phosphate was added to the obtained polyamic acid solution so that the concentration of calcium hydrogen phosphate was 0.05% by weight based on the solid content of the polyamic acid, the same procedure as in Production Example 1 was carried out. A polyimide film (A-2) having a phosphorus content of 0.011% by weight and a thickness of 50 μm was produced.
　（製造例３）
　得られたポリアミド酸溶液に、リン酸水素カルシウムの濃度がポリアミド酸の固形分に対して０．０１重量％となるようにリン酸水素カルシウムを添加した以外は、製造例１と同様にして、リンの含有量０．００２重量％、厚さ５０μｍのポリイミドフィルム（Ａ－３）を作製した。 (Production Example 3)
Except for adding calcium hydrogen phosphate to the obtained polyamic acid solution so that the concentration of calcium hydrogen phosphate was 0.01% by weight based on the solid content of the polyamic acid, the same procedure as in Production Example 1 was carried out. A polyimide film (A-3) having a phosphorus content of 0.002 wt% and a thickness of 50 μm was produced.
　（製造例４）
　得られたポリアミド酸溶液に、リン酸水素カルシウムの濃度がポリアミド酸の固形分に対して０．３０重量％となるようにリン酸水素カルシウムを添加した以外は、製造例１と同様にして、リンの含有量０．０６８重量％、厚さ５０μｍのポリイミドフィルム（Ａ－４）を作製した。 (Production Example 4)
Except that calcium hydrogen phosphate was added to the obtained polyamic acid solution so that the concentration of calcium hydrogen phosphate was 0.30% by weight with respect to the solid content of the polyamic acid, in the same manner as in Production Example 1, A polyimide film (A-4) having a phosphorus content of 0.068 wt% and a thickness of 50 μm was produced.
　（製造例５）
　得られたポリアミド酸溶液に、リン酸水素二アンモニウムの濃度がポリアミド酸の固形分に対して０．１５重量％となるようにリン酸水素二アンモニウムを添加した以外は、製造例１と同様にして、リンの含有量０．０３５重量％、厚さ５０μｍのポリイミドフィルム（Ａ－５）を作製した。 (Production Example 5)
Except that diammonium hydrogen phosphate was added to the obtained polyamic acid solution so that the concentration of diammonium hydrogen phosphate was 0.15 wt% with respect to the solid content of the polyamic acid, the same procedure as in Production Example 1 was performed. Thus, a polyimide film (A-5) having a phosphorus content of 0.035 wt% and a thickness of 50 μm was produced.
　（製造例６）
　得られたポリアミド酸溶液に、フィラーを添加しなかった以外は、製造例１と同様にして、リンの含有量０重量％、厚さ５０μｍのポリイミドフィルム（Ａ－６）を作製した。 (Production Example 6)
A polyimide film (A-6) having a phosphorus content of 0% by weight and a thickness of 50 μm was produced in the same manner as in Production Example 1 except that no filler was added to the obtained polyamic acid solution.
　（製造例７）
　得られたポリアミド酸溶液に、炭酸カルシウムの濃度がポリアミド酸の固形分に対して０．１５重量％となるようにリン酸水素カルシウムの代わりに炭酸カルシウムを添加した以外は、製造例１と同様にして、リンの含有量０重量％、厚さ５０μｍのポリイミドフィルム（Ａ－７）を作製した。 (Production Example 7)
The same procedure as in Production Example 1 except that calcium carbonate was added to the obtained polyamic acid solution instead of calcium hydrogen phosphate so that the concentration of calcium carbonate was 0.15% by weight based on the solid content of the polyamic acid. Thus, a polyimide film (A-7) having a phosphorus content of 0% by weight and a thickness of 50 μm was produced.
　（製造例８）
　得られたポリアミド酸溶液に、リン酸水素カルシウムを濃度がポリアミド酸の固形分に対して０．５０重量％となるように添加した以外は、製造例１と同様にして、リンの含有量０．１１４重量％、厚さ５０μｍのポリイミドフィルム（Ａ－８）を作製した。 (Production Example 8)
A phosphorus content of 0 was obtained in the same manner as in Production Example 1, except that calcium hydrogen phosphate was added to the obtained polyamic acid solution so that the concentration was 0.50% by weight based on the solid content of the polyamic acid. A polyimide film (A-8) having a thickness of 114% by weight and a thickness of 50 μm was produced.
　＜グラファイトシートの製造方法＞
　（実施例１）
　サイズ２００ｍｍ×２００ｍｍ、厚さ５０μｍのポリイミドフィルム（Ａ－１）を、サイズ２２０ｍｍ×２２０ｍｍの黒鉛シートで挟み（ポリイミドフィルム１枚と黒鉛シートとを交互に積層）、窒素雰囲気下で、０．５℃／ｍｉｎの昇温速度で１０００℃まで昇温した後、１０００℃で１０分間熱処理して炭化した。 <Method for producing graphite sheet>
Example 1
A polyimide film (A-1) having a size of 200 mm × 200 mm and a thickness of 50 μm is sandwiched between graphite sheets having a size of 220 mm × 220 mm (one polyimide film and a graphite sheet are alternately laminated), and 0.5% in a nitrogen atmosphere. The temperature was raised to 1000 ° C. at a rate of temperature rise / ° C./min, and then heat treated at 1000 ° C. for 10 minutes for carbonization.
　その後、室温～２２００℃の温度領域では減圧下、２２００℃よりも高い温度領域ではアルゴン雰囲気下で、昇温速度５．０℃／ｍｉｎで２８００℃（黒鉛化最高温度）まで昇温した後、２８００℃で１０分保持してグラファイトシートを作製した。得られたグラファイトシート１枚を、サイズ２００ｍｍ×２００ｍｍ×厚み４００μｍのＰＥＴフィルムで挟み、圧縮成型機を用いて圧縮処理を実施した。加えた圧力は１０ＭＰａとした。圧縮後のグラファイトシートの厚みは２５μｍ、密度は１．８３ｇ／ｃｍ３であった。 Then, after increasing the temperature to 2800 ° C. (maximum graphitization temperature) at a temperature increase rate of 5.0 ° C./min in a temperature range from room temperature to 2200 ° C. under reduced pressure and in an argon atmosphere at a temperature range higher than 2200 ° C., The graphite sheet was produced by holding at 2800 ° C. for 10 minutes. One piece of the obtained graphite sheet was sandwiched between PET films having a size of 200 mm × 200 mm × thickness of 400 μm, and compression processing was performed using a compression molding machine. The applied pressure was 10 MPa. The graphite sheet after compression had a thickness of 25 μm and a density of 1.83 g / cm 3 .
　（実施例２）
　昇温速度０．５℃／ｍｉｎで２８００℃（黒鉛化最高温度）まで昇温した以外は、実施例１と同様にして、実施例２のグラファイトシートを作製した。圧縮後のグラファイトシートの厚みは２４μｍ、密度は１．９ｇ／ｃｍ３であった。 (Example 2)
A graphite sheet of Example 2 was produced in the same manner as in Example 1 except that the temperature was raised to 2800 ° C. (graphitization maximum temperature) at a rate of temperature increase of 0.5 ° C./min. The compressed graphite sheet had a thickness of 24 μm and a density of 1.9 g / cm 3 .
　（実施例３）
　昇温速度０．１℃／ｍｉｎで２８００℃（黒鉛化最高温度）まで昇温した以外は、実施例１と同様にして、実施例３のグラファイトシートを作製した。圧縮後のグラファイトシートの厚みは２３μｍ、密度は１．９９ｇ／ｃｍ３であった。 Example 3
A graphite sheet of Example 3 was produced in the same manner as in Example 1 except that the temperature was raised to 2800 ° C. (graphitization maximum temperature) at a rate of temperature rise of 0.1 ° C./min. The graphite sheet after compression had a thickness of 23 μm and a density of 1.99 g / cm 3 .
　（実施例４）
　ポリイミドフィルム（Ａ－１）の代わりにポリイミドフィルム（Ａ－２）を用いた以外は、実施例１と同様にして、実施例４のグラファイトシートを作製した。圧縮後のグラファイトシートの厚みは２３μｍ、密度は１．９９ｇ／ｃｍ３であった。 Example 4
A graphite sheet of Example 4 was produced in the same manner as in Example 1 except that the polyimide film (A-2) was used instead of the polyimide film (A-1). The graphite sheet after compression had a thickness of 23 μm and a density of 1.99 g / cm 3 .
　（実施例５）
　ポリイミドフィルム（Ａ－１）の代わりにポリイミドフィルム（Ａ－３）を用いた以外は、実施例１と同様にして、実施例５のグラファイトシートを作製した。圧縮後のグラファイトシートの厚みは２２μｍ、密度は２．０８ｇ／ｃｍ３であった。 (Example 5)
A graphite sheet of Example 5 was produced in the same manner as in Example 1 except that the polyimide film (A-3) was used instead of the polyimide film (A-1). The compressed graphite sheet had a thickness of 22 μm and a density of 2.08 g / cm 3 .
　（実施例６）
　ポリイミドフィルム（Ａ－１）の代わりにポリイミドフィルム（Ａ－４）を用いた以外は、実施例３と同様にして、実施例６のグラファイトシートを作製した。圧縮後のグラファイトシートの厚みは２６μｍ、密度は１．７６ｇ／ｃｍ３であった。 (Example 6)
A graphite sheet of Example 6 was produced in the same manner as Example 3 except that the polyimide film (A-4) was used instead of the polyimide film (A-1). The compressed graphite sheet had a thickness of 26 μm and a density of 1.76 g / cm 3 .
　（実施例７）
　昇温速度５．０℃／ｍｉｎで２６００℃（黒鉛化最高温度）まで昇温した以外は、実施例１と同様にして、実施例７のグラファイトシートを作製した。圧縮後のグラファイトシートの厚みは２７μｍ、密度は１．６９ｇ／ｃｍ３であった。 (Example 7)
A graphite sheet of Example 7 was produced in the same manner as in Example 1 except that the temperature was raised to 2600 ° C. (graphitization maximum temperature) at a rate of temperature increase of 5.0 ° C./min. The graphite sheet after compression had a thickness of 27 μm and a density of 1.69 g / cm 3 .
　（実施例８）
　昇温速度５．０℃／ｍｉｎで３０００℃（黒鉛化最高温度）まで昇温した以外は、実施例１と同様にして、実施例７のグラファイトシートを作製した。圧縮後のグラファイトシートの厚みは２１μｍ、密度は２．１８ｇ／ｃｍ３であった。 (Example 8)
A graphite sheet of Example 7 was produced in the same manner as in Example 1 except that the temperature was raised to 3000 ° C. (graphitizing maximum temperature) at a heating rate of 5.0 ° C./min. The graphite sheet after compression had a thickness of 21 μm and a density of 2.18 g / cm 3 .
　（実施例９）
　ポリイミドフィルム（Ａ－１）の代わりにポリイミドフィルム（Ａ－５）を用いた以外は、実施例１と同様にして、実施例９のグラファイトシートを作製した。圧縮後のグラファイトシートの厚みは２５μｍ、密度は１．８３ｇ／ｃｍ３であった。 Example 9
A graphite sheet of Example 9 was produced in the same manner as in Example 1 except that the polyimide film (A-5) was used instead of the polyimide film (A-1). The graphite sheet after compression had a thickness of 25 μm and a density of 1.83 g / cm 3 .
　（比較例１）
　ポリイミドフィルム（Ａ－１）の代わりにポリイミドフィルム（Ａ－６）を用いた以外は、実施例１と同様にして、比較例１のグラファイトシートを作製した。圧縮後のグラファイトシートの厚みは２２μｍ、密度は２．０８ｇ／ｃｍ３であった。 (Comparative Example 1)
A graphite sheet of Comparative Example 1 was produced in the same manner as in Example 1 except that the polyimide film (A-6) was used instead of the polyimide film (A-1). The compressed graphite sheet had a thickness of 22 μm and a density of 2.08 g / cm 3 .
　（比較例２）
　ポリイミドフィルム（Ａ－１）の代わりにポリイミドフィルム（Ａ－７）を用いた以外は、実施例１と同様にして、比較例２のグラファイトシートを作製した。圧縮後のグラファイトシートの厚みは２２μｍ、密度は２．０８ｇ／ｃｍ３であった。 (Comparative Example 2)
A graphite sheet of Comparative Example 2 was produced in the same manner as in Example 1 except that the polyimide film (A-7) was used instead of the polyimide film (A-1). The compressed graphite sheet had a thickness of 22 μm and a density of 2.08 g / cm 3 .
　（比較例３）
　昇温速度２０℃／ｍｉｎで２８００℃（黒鉛化最高温度）まで昇温した以外は、実施例１と同様にして、比較例３のグラファイトシートを作製した。圧縮後のグラファイトシートの厚みは２９μｍ、密度は１．５８ｇ／ｃｍ３であった。 (Comparative Example 3)
A graphite sheet of Comparative Example 3 was produced in the same manner as in Example 1 except that the temperature was raised to 2800 ° C. (graphitization maximum temperature) at a rate of temperature increase of 20 ° C./min. The compressed graphite sheet had a thickness of 29 μm and a density of 1.58 g / cm 3 .
　（比較例４）
　ポリイミドフィルム（Ａ－１）の代わりにポリイミドフィルム（Ａ－８）を用いた以外は、実施例１と同様にして、比較例４のグラファイトシートを作製した。圧縮後のグラファイトシートの厚みは２９μｍ、密度は１．５８ｇ／ｃｍ３であった。 (Comparative Example 4)
A graphite sheet of Comparative Example 4 was produced in the same manner as in Example 1 except that the polyimide film (A-8) was used instead of the polyimide film (A-1). The compressed graphite sheet had a thickness of 29 μm and a density of 1.58 g / cm 3 .
　（比較例５）
　昇温速度５．０℃／ｍｉｎで２４００℃（黒鉛化最高温度）まで昇温した以外は、実施例１と同様にして、比較例５のグラファイトシートを作製した。圧縮後のグラファイトシートの厚みは３１μｍ、密度は１．４７ｇ／ｃｍ３であった。 (Comparative Example 5)
A graphite sheet of Comparative Example 5 was produced in the same manner as in Example 1 except that the temperature was raised to 2400 ° C. (graphitization maximum temperature) at a temperature rising rate of 5.0 ° C./min. The compressed graphite sheet had a thickness of 31 μm and a density of 1.47 g / cm 3 .
　実施例１～９および比較例１～５のグラファイトシートの製造条件および物性を表１に示す。 Table 1 shows the production conditions and physical properties of the graphite sheets of Examples 1 to 9 and Comparative Examples 1 to 5.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　実施例１～９により、リンの含有量が０．０１重量％～０．１０重量％であるグラファイトシートは、熱拡散性及び柔軟性の両方の物性が優れることがわかる。一方、比較例１および２により、リンの含有量が０．０１重量％未満であるグラファイトシートは、熱拡散性は優れるものの、柔軟性に劣ることがわかる。また、比較例３～５により、リンの含有量が０．１０重量％を超えるグラファイトシートは、柔軟性は優れるものの、熱拡散性に劣ることがわかる。 From Examples 1 to 9, it can be seen that the graphite sheet having a phosphorus content of 0.01 wt% to 0.10 wt% is excellent in both physical properties of heat diffusion and flexibility. On the other hand, it can be seen from Comparative Examples 1 and 2 that the graphite sheet having a phosphorus content of less than 0.01% by weight is inferior in flexibility although it has excellent thermal diffusivity. Further, it can be seen from Comparative Examples 3 to 5 that the graphite sheet having a phosphorus content exceeding 0.10% by weight is excellent in flexibility but inferior in thermal diffusivity.
　本発明で得られるグラファイトシートは、例えば、良好な熱拡散性及び柔軟性を有するため電子機器の放熱部材として好適に利用することができる。 The graphite sheet obtained in the present invention can be suitably used as a heat radiating member for electronic equipment because it has good thermal diffusibility and flexibility, for example.

Claims (3)

  1. 　リンの含有量が０．０１重量％以上０．１０重量％以下であるグラファイトシート。 Graphite sheet having a phosphorus content of 0.01 wt% or more and 0.10 wt% or less.
  2. 　リンの含有量が０．０２重量％以上０．０８重量％以下である請求項１に記載のグラファイトシート。 The graphite sheet according to claim 1, wherein the phosphorus content is 0.02 wt% or more and 0.08 wt% or less.
  3. 　リンの含有量が０．０１重量％以上０．１０重量％以下であるグラファイトシートの製造方法であり、
    　リン酸塩の含有量が０．０１重量％以上０．４９重量％以下であるポリイミドフィルムを炭化して炭素質フィルムを得る炭化工程、及び、
    　前記炭素質フィルムを、昇温速度を０．０１℃／ｍｉｎ以上２０℃／ｍｉｎ未満とし、最高温度を２６００℃以上で熱処理してグラファイトシートを得る黒鉛化工程、
    を含むグラファイトシートの製造方法。     A method for producing a graphite sheet, wherein the phosphorus content is 0.01 wt% or more and 0.10 wt% or less,
    A carbonization step of carbonizing a polyimide film having a phosphate content of 0.01 wt% or more and 0.49 wt% or less to obtain a carbonaceous film; and
    A graphitization step of obtaining a graphite sheet by heat-treating the carbonaceous film at a heating rate of 0.01 ° C./min to less than 20 ° C./min and a maximum temperature of 2600 ° C. or more;
    The manufacturing method of the graphite sheet containing this.
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