CN117616073A - Polyimide film for graphite sheet, and method for producing these - Google Patents
Polyimide film for graphite sheet, and method for producing these Download PDFInfo
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- CN117616073A CN117616073A CN202280049098.2A CN202280049098A CN117616073A CN 117616073 A CN117616073 A CN 117616073A CN 202280049098 A CN202280049098 A CN 202280049098A CN 117616073 A CN117616073 A CN 117616073A
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- China
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- graphite sheet
- polyimide film
- acid dianhydride
- diamine component
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 249
- 239000010439 graphite Substances 0.000 title claims abstract description 247
- 229910002804 graphite Inorganic materials 0.000 title claims abstract description 247
- 229920001721 polyimide Polymers 0.000 title claims abstract description 169
- 238000004519 manufacturing process Methods 0.000 title claims description 42
- 150000004985 diamines Chemical class 0.000 claims abstract description 126
- GTDPSWPPOUPBNX-UHFFFAOYSA-N ac1mqpva Chemical compound CC12C(=O)OC(=O)C1(C)C1(C)C2(C)C(=O)OC1=O GTDPSWPPOUPBNX-UHFFFAOYSA-N 0.000 claims abstract description 119
- 239000002253 acid Substances 0.000 claims abstract description 119
- QQGYZOYWNCKGEK-UHFFFAOYSA-N 5-[(1,3-dioxo-2-benzofuran-5-yl)oxy]-2-benzofuran-1,3-dione Chemical compound C1=C2C(=O)OC(=O)C2=CC(OC=2C=C3C(=O)OC(C3=CC=2)=O)=C1 QQGYZOYWNCKGEK-UHFFFAOYSA-N 0.000 claims abstract description 62
- 239000002994 raw material Substances 0.000 claims abstract description 28
- VLDPXPPHXDGHEW-UHFFFAOYSA-N 1-chloro-2-dichlorophosphoryloxybenzene Chemical compound ClC1=CC=CC=C1OP(Cl)(Cl)=O VLDPXPPHXDGHEW-UHFFFAOYSA-N 0.000 claims description 37
- KMKWGXGSGPYISJ-UHFFFAOYSA-N 4-[4-[2-[4-(4-aminophenoxy)phenyl]propan-2-yl]phenoxy]aniline Chemical compound C=1C=C(OC=2C=CC(N)=CC=2)C=CC=1C(C)(C)C(C=C1)=CC=C1OC1=CC=C(N)C=C1 KMKWGXGSGPYISJ-UHFFFAOYSA-N 0.000 claims description 32
- RWCCWEUUXYIKHB-UHFFFAOYSA-N benzophenone Chemical compound C=1C=CC=CC=1C(=O)C1=CC=CC=C1 RWCCWEUUXYIKHB-UHFFFAOYSA-N 0.000 claims description 26
- HLBLWEWZXPIGSM-UHFFFAOYSA-N 4-Aminophenyl ether Chemical compound C1=CC(N)=CC=C1OC1=CC=C(N)C=C1 HLBLWEWZXPIGSM-UHFFFAOYSA-N 0.000 claims description 23
- 230000000379 polymerizing effect Effects 0.000 claims description 10
- XUSNPFGLKGCWGN-UHFFFAOYSA-N 3-[4-(3-aminopropyl)piperazin-1-yl]propan-1-amine Chemical compound NCCCN1CCN(CCCN)CC1 XUSNPFGLKGCWGN-UHFFFAOYSA-N 0.000 abstract 1
- 238000005096 rolling process Methods 0.000 description 47
- 238000000034 method Methods 0.000 description 39
- 238000010438 heat treatment Methods 0.000 description 26
- 239000010408 film Substances 0.000 description 24
- 238000005087 graphitization Methods 0.000 description 22
- 238000003763 carbonization Methods 0.000 description 18
- 239000010410 layer Substances 0.000 description 14
- 108010025899 gelatin film Proteins 0.000 description 13
- 229920005575 poly(amic acid) Polymers 0.000 description 13
- 239000007789 gas Substances 0.000 description 12
- 239000010954 inorganic particle Substances 0.000 description 12
- 239000000243 solution Substances 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 10
- 238000001035 drying Methods 0.000 description 10
- 230000000694 effects Effects 0.000 description 10
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 9
- 239000011259 mixed solution Substances 0.000 description 9
- 230000017525 heat dissipation Effects 0.000 description 8
- 230000008569 process Effects 0.000 description 8
- 238000011156 evaluation Methods 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- 239000010409 thin film Substances 0.000 description 7
- WFDIJRYMOXRFFG-UHFFFAOYSA-N Acetic anhydride Chemical compound CC(=O)OC(C)=O WFDIJRYMOXRFFG-UHFFFAOYSA-N 0.000 description 6
- 150000008065 acid anhydrides Chemical class 0.000 description 6
- 238000005259 measurement Methods 0.000 description 6
- 239000003960 organic solvent Substances 0.000 description 6
- 230000000704 physical effect Effects 0.000 description 6
- ARCGXLSVLAOJQL-UHFFFAOYSA-N trimellitic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C(C(O)=O)=C1 ARCGXLSVLAOJQL-UHFFFAOYSA-N 0.000 description 6
- 229910052782 aluminium Inorganic materials 0.000 description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 5
- 239000011888 foil Substances 0.000 description 5
- 239000011261 inert gas Substances 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 238000006116 polymerization reaction Methods 0.000 description 5
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- FUFJGUQYACFECW-UHFFFAOYSA-L calcium hydrogenphosphate Chemical compound [Ca+2].OP([O-])([O-])=O FUFJGUQYACFECW-UHFFFAOYSA-L 0.000 description 4
- 125000006159 dianhydride group Chemical group 0.000 description 4
- AWJUIBRHMBBTKR-UHFFFAOYSA-N isoquinoline Chemical compound C1=NC=CC2=CC=CC=C21 AWJUIBRHMBBTKR-UHFFFAOYSA-N 0.000 description 4
- 230000037303 wrinkles Effects 0.000 description 4
- CBCKQZAAMUWICA-UHFFFAOYSA-N 1,4-phenylenediamine Chemical compound NC1=CC=C(N)C=C1 CBCKQZAAMUWICA-UHFFFAOYSA-N 0.000 description 3
- 239000004952 Polyamide Substances 0.000 description 3
- 239000012298 atmosphere Substances 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- WKDNYTOXBCRNPV-UHFFFAOYSA-N bpda Chemical compound C1=C2C(=O)OC(=O)C2=CC(C=2C=C3C(=O)OC(C3=CC=2)=O)=C1 WKDNYTOXBCRNPV-UHFFFAOYSA-N 0.000 description 3
- 239000001506 calcium phosphate Substances 0.000 description 3
- 238000010000 carbonizing Methods 0.000 description 3
- 235000019700 dicalcium phosphate Nutrition 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000005187 foaming Methods 0.000 description 3
- 229920002647 polyamide Polymers 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- LVRNKEBRXQHJIN-UHFFFAOYSA-N 4-ethylphthalic acid Chemical compound CCC1=CC=C(C(O)=O)C(C(O)=O)=C1 LVRNKEBRXQHJIN-UHFFFAOYSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 239000004642 Polyimide Substances 0.000 description 2
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 description 2
- SMWDFEZZVXVKRB-UHFFFAOYSA-N Quinoline Chemical compound N1=CC=CC2=CC=CC=C21 SMWDFEZZVXVKRB-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 150000008064 anhydrides Chemical class 0.000 description 2
- 229910000019 calcium carbonate Inorganic materials 0.000 description 2
- 229910000389 calcium phosphate Inorganic materials 0.000 description 2
- 235000011010 calcium phosphates Nutrition 0.000 description 2
- 238000003490 calendering Methods 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000012024 dehydrating agents Substances 0.000 description 2
- 239000011229 interlayer Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 description 2
- GEYOCULIXLDCMW-UHFFFAOYSA-N 1,2-phenylenediamine Chemical compound NC1=CC=CC=C1N GEYOCULIXLDCMW-UHFFFAOYSA-N 0.000 description 1
- WZCQRUWWHSTZEM-UHFFFAOYSA-N 1,3-phenylenediamine Chemical compound NC1=CC=CC(N)=C1 WZCQRUWWHSTZEM-UHFFFAOYSA-N 0.000 description 1
- 125000001140 1,4-phenylene group Chemical group [H]C1=C([H])C([*:2])=C([H])C([H])=C1[*:1] 0.000 description 1
- BSKHPKMHTQYZBB-UHFFFAOYSA-N 2-methylpyridine Chemical compound CC1=CC=CC=N1 BSKHPKMHTQYZBB-UHFFFAOYSA-N 0.000 description 1
- LJGHYPLBDBRCRZ-UHFFFAOYSA-N 3-(3-aminophenyl)sulfonylaniline Chemical compound NC1=CC=CC(S(=O)(=O)C=2C=C(N)C=CC=2)=C1 LJGHYPLBDBRCRZ-UHFFFAOYSA-N 0.000 description 1
- ZBMISJGHVWNWTE-UHFFFAOYSA-N 3-(4-aminophenoxy)aniline Chemical compound C1=CC(N)=CC=C1OC1=CC=CC(N)=C1 ZBMISJGHVWNWTE-UHFFFAOYSA-N 0.000 description 1
- TYKLCAKICHXQNE-UHFFFAOYSA-N 3-[(2,3-dicarboxyphenyl)methyl]phthalic acid Chemical compound OC(=O)C1=CC=CC(CC=2C(=C(C(O)=O)C=CC=2)C(O)=O)=C1C(O)=O TYKLCAKICHXQNE-UHFFFAOYSA-N 0.000 description 1
- NMGBFVPQUCLJGM-UHFFFAOYSA-N 3-ethylphthalic acid Chemical compound CCC1=CC=CC(C(O)=O)=C1C(O)=O NMGBFVPQUCLJGM-UHFFFAOYSA-N 0.000 description 1
- AVCOFPOLGHKJQB-UHFFFAOYSA-N 4-(3,4-dicarboxyphenyl)sulfonylphthalic acid Chemical compound C1=C(C(O)=O)C(C(=O)O)=CC=C1S(=O)(=O)C1=CC=C(C(O)=O)C(C(O)=O)=C1 AVCOFPOLGHKJQB-UHFFFAOYSA-N 0.000 description 1
- CQMIJLIXKMKFQW-UHFFFAOYSA-N 4-phenylbenzene-1,2,3,5-tetracarboxylic acid Chemical compound OC(=O)C1=C(C(O)=O)C(C(=O)O)=CC(C(O)=O)=C1C1=CC=CC=C1 CQMIJLIXKMKFQW-UHFFFAOYSA-N 0.000 description 1
- AQVOMFPTJXMAQE-UHFFFAOYSA-N 4-propylphthalic acid Chemical compound CCCC1=CC=C(C(O)=O)C(C(O)=O)=C1 AQVOMFPTJXMAQE-UHFFFAOYSA-N 0.000 description 1
- 235000019739 Dicalciumphosphate Nutrition 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 125000003277 amino group Chemical group 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 239000012300 argon atmosphere Substances 0.000 description 1
- HFACYLZERDEVSX-UHFFFAOYSA-N benzidine Chemical compound C1=CC(N)=CC=C1C1=CC=C(N)C=C1 HFACYLZERDEVSX-UHFFFAOYSA-N 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 125000002843 carboxylic acid group Chemical group 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000000748 compression moulding Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 229910000390 dicalcium phosphate Inorganic materials 0.000 description 1
- 229940038472 dicalcium phosphate Drugs 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000004299 exfoliation Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- OBKARQMATMRWQZ-UHFFFAOYSA-N naphthalene-1,2,5,6-tetracarboxylic acid Chemical compound OC(=O)C1=C(C(O)=O)C=CC2=C(C(O)=O)C(C(=O)O)=CC=C21 OBKARQMATMRWQZ-UHFFFAOYSA-N 0.000 description 1
- KQSABULTKYLFEV-UHFFFAOYSA-N naphthalene-1,5-diamine Chemical compound C1=CC=C2C(N)=CC=CC2=C1N KQSABULTKYLFEV-UHFFFAOYSA-N 0.000 description 1
- DOBFTMLCEYUAQC-UHFFFAOYSA-N naphthalene-2,3,6,7-tetracarboxylic acid Chemical compound OC(=O)C1=C(C(O)=O)C=C2C=C(C(O)=O)C(C(=O)O)=CC2=C1 DOBFTMLCEYUAQC-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- CLYVDMAATCIVBF-UHFFFAOYSA-N pigment red 224 Chemical compound C=12C3=CC=C(C(OC4=O)=O)C2=C4C=CC=1C1=CC=C2C(=O)OC(=O)C4=CC=C3C1=C42 CLYVDMAATCIVBF-UHFFFAOYSA-N 0.000 description 1
- 239000002798 polar solvent Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000013557 residual solvent Substances 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000000859 sublimation Methods 0.000 description 1
- 230000008022 sublimation Effects 0.000 description 1
- CXVGEDCSTKKODG-UHFFFAOYSA-N sulisobenzone Chemical compound C1=C(S(O)(=O)=O)C(OC)=CC(O)=C1C(=O)C1=CC=CC=C1 CXVGEDCSTKKODG-UHFFFAOYSA-N 0.000 description 1
- 150000003512 tertiary amines Chemical class 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Materials Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Carbon And Carbon Compounds (AREA)
- Manufacture Of Macromolecular Shaped Articles (AREA)
Abstract
The invention aims to provide a polyimide film capable of providing a graphite sheet with excellent heat conductivity, surface property and flexibility with good productivity. The above problems are solved by a polyimide film comprising an acid dianhydride component and a diamine component as raw materials, wherein the total content of BTDA, ODPA and BAPP is 1 to 35 mol% based on 200 mol% of the total amount of the acid dianhydride component and the diamine component.
Description
Technical Field
The present invention relates to a polyimide film for a graphite sheet, and a method for producing the same.
Background
Since graphite sheets have excellent heat conductivity, they are used as heat radiation members for various electronic devices such as computers, semiconductor elements mounted on electric devices, and other heat generating components.
As a method for producing such a graphite sheet, for example, patent documents 1 and 2 describe a technique for producing a graphite sheet by heat-treating (graphitizing) a polyimide film.
Prior art literature
Patent literature
Patent document 1: WO2015/080264 publication
Patent document 2: japanese laid-open patent publication No. 2000-247619
Disclosure of Invention
Problems to be solved by the invention
However, in the above-described technique, there is room for improvement in the physical properties, particularly thermal conductivity, surface properties and flexibility of the resulting graphite sheet.
An object of an embodiment of the present invention is to provide a polyimide film capable of providing a graphite sheet excellent in thermal conductivity, surface properties and flexibility with good productivity.
Solution for solving the problem
The present inventors have conducted intensive studies to solve the above problems, and as a result, have completed the present invention.
That is, an embodiment of the present invention includes the following.
A polyimide film for a graphite sheet, which is a polyimide film comprising, as raw materials, an acid dianhydride component and a diamine component, wherein the acid dianhydride component comprises 65 to 100 mol% of pyromellitic dianhydride, 0 to 35 mol% of at least one of 3,3', 4' -benzophenone tetracarboxylic dianhydride and 4,4' -oxydiphthalic anhydride in 100 mol% of the total amount of the acid dianhydride component, and the diamine component comprises 65 to 100 mol% of 4,4' -diaminodiphenyl ether, 0 to 35 mol% of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane in 100 mol% of the total amount of the diamine component, and the total content of the 3,3', 4' -benzophenone tetracarboxylic dianhydride, the 4,4' -oxydiphthalic anhydride and the 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane is 1 to 35 mol% relative to the total amount of the acid dianhydride component and the diamine component of 200 mol%.
A method for producing a graphite sheet, comprising a step of heat-treating a polyimide film for a graphite sheet to 2400 ℃ or higher, wherein the polyimide film for a graphite sheet is a polyimide film which comprises an acid dianhydride component and a diamine component, wherein the acid dianhydride component comprises at least one of 65 to 100 mol% of pyromellitic dianhydride, 3', 4' -benzophenone tetracarboxylic dianhydride and 4,4 '-oxydiphthalic anhydride, and 0 to 35 mol% of at least one of the 3,3',4 '-benzophenone tetracarboxylic dianhydride and 4,4' -oxydiphthalic anhydride, and the diamine component comprises at least one of 65 to 100 mol% of 4,4 '-diaminodiphenyl ether, 0 to 35 mol% of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane, and wherein the total amount of the 3,3',4 '-benzophenone tetracarboxylic dianhydride, the 4,4' -oxydiphthalic anhydride and the 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane is 1 to 35 mol% of the total amount of the diamine component, relative to 100 mol% of the total amount of the acid dianhydride component and the diamine component.
A method for producing a polyimide film, which comprises a step of polymerizing an acid dianhydride component containing 65 to 100 mol% of pyromellitic dianhydride, 0 to 35 mol% of at least one of 3,3', 4' -benzophenone tetracarboxylic dianhydride and 4, 4-oxybisphthalic anhydride, and a diamine component containing 65 to 100 mol% of 4,4 '-diaminodiphenyl ether, 0 to 35 mol% of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane, and a total content of the 3,3',4 '-benzophenone tetracarboxylic dianhydride, the 4,4' -oxybisphthalic anhydride and the 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane being 1 to 35 mol% relative to a total amount of the acid dianhydride component and the diamine component of 100 mol%.
ADVANTAGEOUS EFFECTS OF INVENTION
According to an embodiment of the present invention, a polyimide film that can provide a graphite sheet excellent in thermal conductivity, surface properties, and flexibility with good productivity can be provided.
Detailed Description
An embodiment of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to the configurations described below, and various modifications can be made within the scope of the claims, and embodiments and examples obtained by appropriately combining the technical means disclosed in the different embodiments and examples are also included in the technical scope of the present invention. The academic literature and patent literature described in the present specification are all incorporated by reference in the present specification. Unless otherwise specified in the present specification, "a to B" representing a numerical range means "a or more and B or less".
< 1. Technical idea of the invention >
In recent years, with the increase in performance of electronic devices, thick graphite sheets (thick graphite sheets) having more excellent thermal conductivity have been demanded. Thick graphite sheets can be produced by heat treatment (graphitization) of polyimide films having a thickness. However, as described in patent document 2 and the like, in the case of simply increasing the thickness of the conventional polyimide film, the graphite sheet containing the polyimide film as a raw material (heat-treated) has problems such as easy peeling of the surface of the graphite sheet and poor productivity.
In addition, with the miniaturization of electronic devices in recent years, graphite sheets are also required to have excellent flexibility in order to be disposed in a limited space within a small-sized electronic device.
Under the circumstances as described above, the present inventors have conducted intensive studies in order to provide a polyimide film capable of providing a graphite sheet excellent in thermal conductivity, surface properties and productivity, in particular, a polyimide film capable of providing a graphite sheet excellent in thermal conductivity, surface properties and productivity even when a polyimide film having a thickness capable of providing a thick graphite sheet is produced.
In the course of intensive studies to solve the above problems, the present inventors focused on the exhaust gas (out gas) generated in the thick graphite sheet when the polyimide film is heat-treated, which is one cause of the surface properties and productivity degradation of the thick graphite sheet.
In the case of producing a conventional relatively thin graphite sheet, an acid anhydride (PMDA, BPDA, etc.) and/or a diamine (ODA, PDA, etc.) having an effect of improving the orientation of a polyimide film, that is, an effect of improving the orientation of graphite (graphite layer) in the obtained graphite sheet, are used as raw materials of the polyimide film in order to improve interlayer strength and the like. However, in a thick graphite sheet, since the graphite layers are thicker (the number of layers of the graphite layers increases), when the acid anhydride and/or diamine having the effect of improving the orientation of the polyimide film is used as a raw material for the polyimide film, exhaust gas generated by the heat treatment of the polyimide film is blocked by the plurality of graphite layers having high orientation, and it becomes difficult to exhaust the exhaust gas from the inside of the graphite sheet. Further, it is considered that as the heating proceeds, the amount of the exhaust gas increases to push up the surface of the graphite sheet, and thus, a part of the graphite layer is peeled off from the surface of the graphite sheet, and the surface properties of the graphite sheet decrease, and further, the graphite sheet becomes excessively thick due to the bulge (foaming) of the surface of the graphite sheet caused by the exhaust gas pushing up the graphite sheet, and thus, the productivity of the graphite sheet decreases.
As a result of further intensive studies with a view to exhaust gas generated in graphite flake, the present inventors have newly found that: the orientation of the polyimide film can be moderately disturbed by using an acid anhydride (BTDA, ODPA, etc.) and/or diamine (BAPP, etc.) having an effect of disturbing (reducing) the orientation of the polyimide film as the raw material of the polyimide film; when the polyimide film is subjected to a heat treatment, the orientation of the carbonaceous film can be appropriately disturbed, and the outgas generated in the graphite sheet can be appropriately removed; and, the resulting graphite sheet is excellent in thermal conductivity, surface properties, flexibility and productivity, thereby completing the present invention.
As described above, the polyimide film according to an embodiment of the present invention can appropriately remove outgas during the heat treatment. Therefore, the reduction in the surface properties and productivity of the graphite sheet due to the exhaust gas can be suppressed. Thus, it is particularly suitable for the manufacture of thick graphite sheets.
In addition, the present inventors have newly found that: when the acid anhydride and/or diamine having an effect of disturbing the orientation of the polyimide film is used in excess in addition to the acid anhydride and/or diamine having an effect of improving the orientation of the polyimide film, exhaust gas can be removed, but the orientation of the graphite layer of the obtained graphite sheet is excessively disturbed, and therefore, the thermal diffusivity and flexibility cannot satisfy the physical properties required for the graphite sheet as a heat dissipation member in particular.
That is, the present invention has found that the amount of acid anhydride and/or diamine used, which have an effect of disturbing the orientation of the polyimide film, can satisfy both removal of exhaust gas generated during heat treatment and physical properties required for the graphite sheet as a heat dissipation member. The technology based on such a concept is a technology which has not been known in the past, and is a surprising technology.
< 2 polyimide film >)
Hereinafter, a polyimide film according to an embodiment of the present invention (hereinafter, may be referred to as the present polyimide film) will be described in detail. The polyimide film for a graphite sheet used in the present production method is a polyimide film comprising, as raw materials, an acid dianhydride component and a diamine component, wherein the acid dianhydride component comprises 65 to 100 mol% of pyromellitic dianhydride (PMDA), 0 to 35 mol% of at least any one of 3,3', 4' -Benzophenone Tetracarboxylic Dianhydride (BTDA) and 4,4' -oxydiphthalic anhydride (ODPA), and the diamine component comprises 65 to 100 mol% of 4,4' -diaminodiphenyl ether (ODA), 0 to 35 mol% of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane (BAPP), and the total amount of 3,3', 4' -Benzophenone Tetracarboxylic Dianhydride (BTDA), 4' -oxydiphthalic anhydride (ODPA), and 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane (BAPP) is 200 mol% relative to the total amount of the acid dianhydride component and the diamine component, and the total amount of the diamine component is 1 to 35 mol%.
Since the polyimide film has the above-described structure, a graphite sheet excellent in heat conductivity, surface properties and flexibility can be provided with good productivity by using the polyimide film as a raw material. That is, the polyimide film can be suitably used for the production of graphite sheets. Therefore, the polyimide film may also be referred to as a polyimide film for a graphite sheet.
(acid dianhydride component)
The acid dianhydride component as a raw material of the present polyimide film contains 65 to 100 mol% of pyromellitic dianhydride (PMDA), and at least one of 3,3', 4' -Benzophenone Tetracarboxylic Dianhydride (BTDA) and 4,4' -oxydiphthalic anhydride (ODPA) in an amount of 0 to 35 mol%. The acid dianhydride component may contain only any one of BTDA and ODPA, or may contain 2 kinds of the components. In the polyimide film, when the diamine component to be described later is BAPP at 1 mol% or more as a raw material, the acid dianhydride component may contain BTDA and/or ODPA, or may not contain any of BTDA and ODPA.
In one embodiment of the present invention, the amount of PMDA contained in the acid dianhydride component is 65 mol% or more, preferably 70 mol% or more, and more preferably 80 mol% or more, based on 100 mol% of the total amount of the acid dianhydride component. The polyimide film can provide a polyimide film (and a carbonaceous film) having an appropriate orientation by containing PMDA at 65 mol% or more. The amount of PMDA contained in the acid dianhydride component may be 85 mol% or more, 90 mol% or more, 95 mol% or more, or 100 mol% or more.
Wherein the acid dianhydride component preferably comprises 100 mole% PMDA, in which case the diamine component preferably comprises 65 to 99 mole% ODA, 1 to 35 mole% BAPP. According to this structure, the obtained graphite sheet has excellent thermal diffusivity and flexibility.
In one embodiment of the present invention, when the acid dianhydride component contains at least one of BTDA and ODPA, the content of BTDA and ODPA (total amount of BTDA and ODPA) is 1 mol% or more, preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, based on 100 mol% of the total amount of the acid dianhydride component. The upper limit of the content of BTDA and ODPA is 35 mol% or less, preferably 30 mol% or less, and more preferably 25 mol% or less. When the acid dianhydride component contains at least 1 mol% of either one of BTDA and ODPA, the orientation of the obtained polyimide film (and carbonaceous film) can be moderately disturbed. This can provide a graphite sheet excellent in thermal conductivity, surface properties and flexibility with good productivity. When the content (total amount) of at least one of BTDA and ODPA in the acid dianhydride component is 35 mol% or less, the orientation of the obtained graphite sheet is not excessively disturbed, and the heat diffusion rate and flexibility of the obtained graphite sheet are improved. In other words, if the content (total amount) of BTDA and ODPA exceeds 35%, the orientation of the obtained graphite sheet is excessively disturbed, and the thermal conductivity and flexibility of the graphite sheet tend to be poor.
The polyimide film may contain, as an acid dianhydride component, other acid dianhydrides in addition to the PMDA, BTDA, and ODPA. Examples of the other acid dianhydride include 2,3,6, 7-naphthalene tetracarboxylic dianhydride, 1,2,5, 6-naphthalene tetracarboxylic dianhydride, 2', 3' -biphenyl tetracarboxylic dianhydride, 3',4,4' -biphenyltetracarboxylic acid dianhydride (BPDA), 2-bis (3, 4-dicarboxyphenyl) propane dianhydride, 3,4,9, 10-perylenetetracarboxylic acid dianhydride, 1- (3, 4-dicarboxyphenyl) ethane dianhydride, 1-bis (2, 3-dicarboxyphenyl) ethane dianhydride, 1-bis (3, 4-dicarboxyphenyl) ethane dianhydride, bis (2, 3-dicarboxyphenyl) methane dianhydride, bis (3, 4-dicarboxyphenyl) sulfone dianhydride, p-phenylene bis (trimellitic acid monoester dianhydride), ethylene bis (trimellitic acid monoester diacid dianhydride), bisphenol a bis (trimellitic acid monoester diacid dianhydride), and the like. The other acid dianhydrides may be used alone, or a plurality of these may be mixed in an arbitrary ratio.
The content of the other acid dianhydride in the acid dianhydride component as the raw material of the present polyimide film is 35 mol% or less, preferably 20 mol% or less, more preferably 10 mol% or less, further preferably 5 mol% or less, further preferably 1 mol% or less, and particularly preferably 0 mol% based on 100 mol% of the total amount of the acid dianhydride component. That is, the acid dianhydride component as a raw material of the present polyimide film particularly preferably does not contain other acid dianhydrides.
(diamine component)
The diamine component as a raw material of the present polyimide film contains 65 to 100 mol% of 4,4' -diaminodiphenyl ether (ODA), and 0 to 35 mol% of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane (BAPP). In the polyimide film, when 1 mol% or more of BTDA or ODPA is used as a raw material for the acid dianhydride component, the diamine component may or may not contain BAPP.
In one embodiment of the present invention, the amount of ODA contained in the diamine component is 65 mol% or more, preferably 70 mol% or more, and more preferably 80 mol% or more, relative to 100 mol% of the total amount of the diamine component. The polyimide film can provide a polyimide film (and a carbonaceous film) having a suitable orientation by containing 65 mol% or more of the ODA. The amount of ODA contained in the diamine component may be 85 mol% or more, 90 mol% or more, 95 mol% or more, or 100 mol% or more.
Wherein the diamine component preferably contains 100 mol% of ODA, in which case it is preferable that the acid dianhydride component contains 65 to 99 mol% of PMDA, and at least any one of BTDA and ODPA 1 to 35 mol%. According to this structure, the obtained graphite sheet has excellent thermal diffusivity and flexibility.
In one embodiment of the present invention, when the diamine component contains BAPP, the content of BAPP is 1 mol% or more, preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, based on 100 mol% of the total diamine component. The upper limit of the BAPP content is 35 mol% or less, preferably 30 mol% or less, more preferably 25 mol% or less. When the diamine component contains 1 mol% or more of BAPP, the orientation of the obtained polyimide film (and carbonaceous film) can be moderately disturbed. This can provide a graphite sheet excellent in thermal conductivity, surface properties and flexibility with good productivity. When the BAPP content in the diamine component is 35 mol% or less, the orientation of the graphite sheet is not excessively disturbed, and the obtained graphite sheet has excellent thermal diffusivity and flexibility.
The polyimide film may contain, as a diamine component, other diamines in addition to the ODA and BAPP. As a further diamine, the diamine may be used, examples include p-Phenylenediamine (PDA), 4 '-diaminodiphenylmethane, benzidine, 3' -dichlorobenzidine, 4 '-diaminodiphenylsulfide 3,3' -diaminodiphenyl sulfone, 4 '-diaminodiphenyl sulfone, 3' -diaminodiphenyl ether, 3,4 '-diaminodiphenyl ether 1, 5-diaminonaphthalene, 4' -diaminodiphenyldiethylsilane, 4 '-diaminodiphenylsilane, 4' -diaminodiphenylethylphosphine oxide, 4 '-diaminodiphenylN-methylamine, 4' -diaminodiphenylN-aniline, 1, 3-diaminobenzene, 1, 2-diaminobenzene, and their analogs. These diamines may be used alone, or a plurality of these diamines may be mixed in an arbitrary ratio.
The content of the other diamine in the diamine component as the raw material of the polyimide film is 35 mol% or less, preferably 20 mol% or less, more preferably 10 mol% or less, still more preferably 5 mol% or less, still more preferably 1 mol% or less, and particularly preferably 0 mol% based on 100 mol% of the total diamine component. That is, the diamine component as a raw material of the present polyimide film preferably contains no other diamine.
(total content of BTDA, ODPA and BAPP)
The polyimide film contains 1 to 35 mol% of the total of the BTDA, ODPA, and BAPP, based on 200 mol% of the total amount of the acid dianhydride component and the diamine component. In the present polyimide film, the amounts of BTDA, ODPA, and BAPP used are in the above ranges, so that the orientation of the present polyimide film (and the carbonaceous film) can be appropriately disturbed. Therefore, the graphite sheet containing the polyimide film as a raw material is excellent in thermal conductivity, surface properties and flexibility, and can be provided with good productivity.
In the polyimide film, the lower limit of the total content of BTDA, ODPA, and BAPP is 1 mol% or more, preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, relative to 200 mol% of the total amount of the acid dianhydride component and the diamine component. The upper limit of the total content of BTDA, ODPA, and BAPP is 35 mol% or less, preferably 30 mol% or less, and more preferably 25 mol% or less.
The polyimide film is prepared from the acid dianhydride component and the diamine component in substantially equimolar amounts. In the present specification, the substantially equimolar amount means that the ratio of the molar amounts of 2 or more species (for example, an acid dianhydride component and a diamine component) which are different from each other is 100: 98-100: 102, preferably 100:100. that is, in the present specification, "0 to 35 mol% of at least one of BTDA and ODPA is contained in 100 mol% of the total amount of the acid dianhydride component" is also said to be "200 mol% of the total amount of the acid dianhydride component and the diamine component is contained in 0 to 35 mol% of at least one of BTDA and ODPA", and "0 to 35 mol% of BAPP is contained in 100 mol% of the total amount of the diamine component" is also said to be "200 mol% of the total amount of the acid dianhydride component and the diamine component is contained in 0 to 35 mol% of BAPP". That is, "the total content of BTDA, ODPA, and BAPP with respect to the total amount of the acid dianhydride component and the diamine component is 200 mol%, can be calculated as the total content of BTDA and ODPA in the acid dianhydride component and the BAPP in the diamine component.
(inorganic particles)
The polyimide film may contain inorganic particles (fillers). When the polyimide film contains inorganic particles, a graphite sheet having more excellent thermal diffusivity and interlayer strength can be provided. The lower limit of the content of the inorganic particles in the polyimide film is preferably 0.01 wt% or more, more preferably 0.02 wt%, and still more preferably 0.03 wt%. The upper limit of the content of the inorganic particles is preferably 0.30 wt%, more preferably 0.20 wt%, and still more preferably 0.15 wt%.
Examples of the inorganic particles that can be contained in the polyimide film include calcium carbonate (CaCO) 3 ) Silica, dicalcium phosphate (CaHPO) 4 ) Calcium phosphate (Ca) 2 P 2 O 7 ) Etc. Among these inorganic particles, inorganic particles containing phosphorus such as calcium hydrogen phosphate and calcium phosphate are preferable.
The average particle diameter of the inorganic particles that the polyimide film may contain is not particularly limited, but is preferably greater than 1.5 μm, more preferably 1.8 μm or more.
In the present specification, the average particle diameter of the inorganic particles means a volume average particle diameter, and is a value measured by using a particle size distribution measuring apparatus MT3000II manufactured by microtrac corporation for the inorganic particles dispersed in dimethylformamide.
(thickness of polyimide film)
The thickness of the polyimide film is preferably 80 μm to 200 μm, more preferably 90 μm to 180 μm, still more preferably 100 μm to 160 μm, still more preferably 110 μm to 140 μm, particularly preferably 115 μm to 135 μm. When the thickness of the polyimide film is in the above range, a graphite sheet having more excellent thermal diffusivity can be provided.
The lower limit of the thickness of the polyimide film according to an embodiment of the present invention is preferably 80 μm or more, more preferably 90 μm or more, still more preferably 100 μm or more, still more preferably 110 μm or more, and particularly preferably 115 μm or more. The upper limit of the thickness of the polyimide film is preferably 200 μm or less, more preferably 180 μm or less, still more preferably 160 μm or less, still more preferably 140 μm or less, and particularly preferably 135 μm or less.
In the conventional polyimide film, when the thickness of the polyimide film is increased (for example, the thickness is 80 μm or more) in order to provide a thick graphite sheet, there is a problem that the surface properties, productivity, and the like of the obtained graphite sheet become poor. That is, the present polyimide film can be suitably used as a polyimide film having a thickness.
< 3. Method for producing polyimide film >
The method for producing a polyimide film according to an embodiment of the present invention (hereinafter, may be referred to as the method for producing a polyimide film) is not particularly limited, and for example, a method having the following steps i) to iv) is preferable;
i) A step of reacting an acid dianhydride component with a diamine component in an organic solvent to obtain a polyamic acid solution,
ii) a step of applying the polyamic acid solution to a support to form a mixed solution layer,
iii) Drying (heating) the mixed solution layer on the support to form a self-supporting gel film, and then peeling the gel film from the support,
iv) a step of heating the peeled gel film to imidize the residual amic acid, and drying the gel film to obtain a polyimide film.
The step i) in the method for producing a polyimide film is not particularly limited as long as the polyamide acid can be obtained by polymerizing (as a raw material) the acid dianhydride component and the diamine component described in detail in the above item < 2. Polyimide film > and any of the following polymerization methods (1) to (5) can be suitably used, for example.
(1) A method in which a diamine component is dissolved in an organic solvent (organic polar solvent), and the diamine component is reacted with an acid dianhydride component in an amount substantially equal to the diamine component to polymerize the diamine component.
(2) The acid dianhydride component is reacted with a diamine component in an excessively small molar amount relative thereto in an organic solvent to obtain a prepolymer having acid dianhydride groups at both terminals. Next, the diamine component and the prepolymer are polymerized so that the total amount of the entire polymerization step is substantially equal to the molar amount of the acid dianhydride component.
Specific examples of the method (2) include the following methods: the prepolymer having acid dianhydride at both ends is synthesized using a diamine component and an acid dianhydride component, and a diamine component having the same composition as the diamine component used for the synthesis of the prepolymer or a diamine component having a different composition is reacted with the prepolymer to synthesize a polyamic acid. In the method (2), the diamine component to be reacted with the prepolymer may be the same as or a diamine component having a different composition from the diamine component used for the synthesis of the prepolymer.
(3) The acid dianhydride component is reacted with an excessive molar amount of a diamine component relative thereto in an organic solvent to obtain a prepolymer having amino groups at both terminals. Then, a diamine component is added to the prepolymer, and then the acid dianhydride component is added so that the total amount of the acid dianhydride component and the diamine component used in the entire polymerization step becomes substantially equal in molar amount, thereby polymerizing the prepolymer and the acid dianhydride component.
(4) A method in which the acid dianhydride component is dissolved and/or dispersed in an organic solvent, and then the diamine component is added so that the amount of the diamine component is substantially equal to the molar amount of the acid dianhydride component, thereby polymerizing the acid dianhydride component and the diamine component.
(5) A method of polymerizing a mixture of an acid dianhydride component and a diamine component in an organic solvent in a substantially equimolar amount.
i) The acid dianhydride component and the diamine component (supplied to polymerization) reacted in the step become the acid dianhydride component and the diamine component as the raw materials of the obtained polyimide film. Accordingly, the step i) in the present method for producing a polyimide film can be expressed as follows: and polymerizing an acid dianhydride component and a diamine component, wherein the acid dianhydride component comprises 65 to 100 mol% of pyromellitic dianhydride (PMDA), 0 to 35 mol% of at least one of 3,3', 4' -Benzophenone Tetracarboxylic Dianhydride (BTDA) and 4,4' -oxydiphthalic anhydride (ODPA), and the diamine component comprises 65 to 100 mol% of 4,4' -diaminodiphenyl ether (ODA), 0 to 35 mol% of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane (BAPP), and the total content of the 3,3', 4' -Benzophenone Tetracarboxylic Dianhydride (BTDA), the 4,4' -oxydiphthalic anhydride (ODPA) and the 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane (BAPP) is 1 to 35 mol% based on the total amount of the acid dianhydride component and the diamine component, in 100 mol% of the diamine component.
The preferred method for producing the polyimide film can be described as follows: a process for producing a polyimide film, which comprises the step of polymerizing an acid dianhydride component and a diamine component, wherein the acid dianhydride component comprises 65 to 100 mol% of pyromellitic dianhydride (PMDA), 0 to 35 mol% of at least one of 3,3', 4' -Benzophenone Tetracarboxylic Dianhydride (BTDA) and 4,4' -oxydiphthalic anhydride (ODPA), and the diamine component comprises 65 to 100 mol% of 4,4' -diaminodiphenyl ether (ODA), 0 to 35 mol% of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane (BAPP), and the total content of the 3,3', 4' -Benzophenone Tetracarboxylic Dianhydride (BTDA), the 4,4' -oxydiphthalic anhydride (ODPA) and the 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane (BAPP) is 1 to 35 mol% based on the total amount of the acid dianhydride component and the diamine component.
The acid dianhydride component and the diamine component that are reacted (subjected to polymerization) in step i) in the present method for producing a polyimide film may be appropriately referred to as < 2. Polyimide film > above.
In the steps ii) to iv) in the method for producing a polyimide film, the polyimide film can be obtained by imidizing the polyamic acid solution. in the steps ii) to iv), as a method for imidizing the polyamic acid, for example, there can be used: (i) And (ii) a chemical imidization method in which a polyamic acid solution containing an imidization accelerator is heated to imidize the polyamic acid by adding a dehydrating agent (a dehydrating ring-closing agent) represented by an acid dianhydride such as acetic anhydride and/or an imidization accelerator such as a catalyst represented by a tertiary amine such as methyl pyridine, quinoline, isoquinoline, pyridine, or the like to the polyamic acid, without using the imidization accelerator.
In particular, the chemical imidization method is preferable in that the linear expansion coefficient of the obtained polyimide film is easily reduced, the elastic modulus is easily increased, the birefringence is easily increased, and the obtained polyimide film can be rapidly graphitized at a relatively low temperature to obtain a graphite sheet having a good quality. In particular, the use of a combination of a dehydrating agent and an imidization accelerator is preferable because the linear expansion coefficient of the obtained polyimide film can be smaller, the elastic modulus can be larger, and the birefringence can be larger. Further, the chemical imidization method is an industrially advantageous method that allows imidization to be completed in a short time during a heating process because imidization proceeds more rapidly, and that is excellent in productivity.
In the method for producing a polyimide film of the present invention, the support used in step ii) is not particularly limited as long as it is a support that is not dissolved in the polyimide-containing solution and is resistant to the heat required for drying the laminate, and for example, a glass plate, an aluminum foil, an endless stainless steel belt, a stainless steel drum, or the like can be suitably used.
iii) The process is more specifically the following: heating conditions are set according to the thickness and production speed of the finally obtained polyimide film, and at least one of imidization and drying is partially performed on the mixed solution layer (polyamic acid solution) applied to the support, and then a gel film is obtained (peeled) from the support.
iv) the process is more specifically the following: fixing the end of the gel film (the gel film obtained in the step iii), performing a heat treatment in a state of avoiding shrinkage at the time of curing, removing water, a residual solvent, an imidization accelerator, and the like from the gel film, and completely imidizing the residual amic acid (non-imidized amic acid), thereby obtaining a film (polyimide film) containing polyimide. The heating conditions in step iv) may be appropriately set according to the thickness and production speed of the finally obtained film.
The method for drying the mixed solution layer and gel film in step iii) and step iv) is not particularly limited, and examples thereof include a method of heating by a hot air treatment using a hot air oven or the like and/or a radiant heat treatment using a far infrared heater or the like. The drying temperature (heating temperature) in the drying step is not particularly limited as long as a gel film or a polyimide film can be obtained, and for example, the temperature may be 100 to 140℃in the case of hot air treatment and 400 to 500℃in the case of using an infrared heater.
< 4. Graphite flake >)
In one embodiment of the present invention, a graphite sheet is provided which uses the polyimide film as a raw material. The graphite sheet according to one embodiment of the present invention (hereinafter referred to as the present graphite sheet) may be referred to as a graphite sheet obtained by heat-treating the present polyimide film. The graphite sheet contains the polyimide film as a raw material, and thus has excellent thermal conductivity, surface properties, flexibility and productivity. In the present specification, the present graphite sheet refers to both of a graphite sheet before a rolling step (a graphite sheet before rolling) and a graphite sheet after a rolling step (a graphite sheet after rolling), but unless otherwise mentioned, the present graphite sheet refers to a graphite sheet after rolling.
(thermal conductivity)
In the present specification, the thermal conductivity of the graphite sheet can be evaluated by the thermal diffusivity of the graphite sheet (the graphite sheet after being rolled). The thermal diffusivity of the graphite flake is preferably 5.0cm 2 Higher than/s, more preferably 5.5cm 2 Higher than/s, more preferably 6.0m 2 More preferably at least/s, still more preferably at least 6.5cm 2 At least/s, particularly preferably 7.0cm 2 And/s. Thermal diffusivity of 5.0cm 2 The graphite sheet having a heat conductivity of at least/s is excellent. In other words, graphite sheets having excellent heat dissipation properties can be suitably used as heat dissipation members in fields requiring excellent heat dissipation properties such as electronic devices. The thermal diffusion of the graphite sheetThe method of measuring the rate is as described in examples below.
(surface property)
In the present specification, the surface properties of the graphite sheet can be evaluated based on the surface exfoliation of the graphite sheet (the graphite sheet before rolling). That is, in the present specification, the graphite sheet excellent in surface properties means a graphite sheet having no (almost no) surface peeling. The specific evaluation method of the surface peeling of the graphite sheet is as described in examples described later.
(softness)
The graphite sheet (rolled graphite sheet) is a graphite sheet excellent in flexibility. Therefore, the device can be disposed in a limited space such as a small electronic apparatus. In the present specification, a specific method for evaluating flexibility of the graphite sheet is as described in examples described below.
(productivity)
In the present specification, the productivity of the graphite sheet can be evaluated based on the ratio of the thickness of the polyimide film as a raw material to the thickness of the obtained graphite sheet (graphite sheet before rolling) (thickness of the graphite sheet before rolling/thickness of the polyimide film, hereinafter referred to as "GS thickness/PI thickness"). In the case where the GS thickness/PI thickness is larger than a certain value (for example, more than 3.0), particularly in the case of being formed into a roll, the amount of graphite sheets before rolling that can be handled at one time is limited, and thus productivity is poor. On the other hand, the smaller the GS thickness/PI thickness, the larger the amount of the graphite sheet that can be handled at one time becomes, i.e., the graphite sheet having excellent productivity. Specifically, if the GS thickness/PI thickness is 3.0 or less, it can be evaluated that the productivity of the graphite sheet is excellent. The GS thickness/PI thickness is preferably 2.5 or less, more preferably 2.0 or less, further preferably 1.5 or less, further preferably 1.0 or less.
The lower limit of the thickness of the graphite flake (after being rolled) is preferably 45 μm or more, more preferably 50 μm or more, and still more preferably 55 μm or more. The upper limit of the thickness of the graphite sheet after the rolling is preferably 110 μm or less, more preferably 105 μm or less. The thickness of the graphite sheet after the rolling is 45 μm or more, the graphite sheet has a sufficient heat dissipation effect for heat dissipation of electronic devices, and the thickness of the graphite sheet is 110 μm or less, and the graphite sheet can be mounted in thin electronic devices having little space margin.
The density of the graphite flake (after being rolled) according to one embodiment of the present invention is preferably 1.20g/cm 3 The above, more preferably 1.40g/cm 3 The above, further preferably 1.60g/cm 3 The above, further preferably 1.80g/cm 3 The above. The upper limit of the density is not particularly limited, and the graphite flake is usually 2.26g/cm 3 The following is given. If the density of the graphite flake is 1.60g/cm 3 As described above, the graphite sheet has an advantage of exhibiting an excellent heat dissipation effect.
< 5 Process for producing graphite flake >
A method for producing a graphite sheet according to an embodiment of the present invention (hereinafter, may be referred to as the present graphite sheet production method) is as follows: the polyimide film for graphite sheets is a polyimide film prepared from an acid dianhydride component and a diamine component, wherein the acid dianhydride component contains 65 to 100 mol% of pyromellitic dianhydride, 0 to 35 mol% of at least one of 3,3', 4' -benzophenone tetracarboxylic dianhydride and 4,4' -oxydiphthalic anhydride, and the diamine component contains 65 to 100 mol% of 4,4' -diaminodiphenyl ether, 0 to 35 mol% of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane, and the 3,3', 4' -benzophenone tetracarboxylic dianhydride, 4' -oxydiphthalic anhydride and 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane are contained in an amount of 1 to 35 mol% based on the total amount of the acid dianhydride component and the diamine component of 100 mol%. The method for producing the graphite sheet may be also referred to as a method including a step of heat-treating the polyimide film to 2400 ℃.
According to the method for producing a graphite sheet, the graphite sheet of the present invention, that is, a graphite sheet excellent in thermal conductivity, surface properties and flexibility can be provided with good productivity. The polyimide film used in the method for producing a graphite sheet can be appropriately referred to as the item <2. Polyimide film >.
The method for producing the graphite sheet is not particularly limited as long as it includes a step of heat-treating a specific polyimide film (the present polyimide film) to 2400 ℃ or higher, and a so-called polymer thermal decomposition method in which the polyimide film is heat-treated under an inert gas atmosphere and reduced pressure is preferable. Specifically, the present method for producing a graphite sheet preferably comprises the steps of: a carbonization step of preheating the polyimide film at a temperature of about 1000 ℃ to obtain a carbonized polyimide film; a graphitization step of performing graphitization by performing heat treatment (heating) at a temperature of 2400 ℃ or higher on the carbonized polyimide film produced in the carbonization step; and a rolling step of rolling the same. In the present method for producing a graphite sheet, the carbonization step and the graphitization step may be performed continuously, or only the graphitization step may be performed separately after the carbonization step is completed.
Hereinafter, the present method for producing a graphite sheet will be described in detail with reference to a method including a carbonization step, a graphitization step, and a rolling step.
(carbonization step)
The carbonization step is a step of heat-treating the polyimide film to a temperature of about 1000 ℃ to carbonize (carbonize) the polyimide film. The carbonization method of the polyimide film in the carbonization step is not particularly limited, and for example, a rectangular polyimide film may be carbonized in a state of being laminated with a graphite sheet, a rolled polyimide film may be carbonized while being kept in a rolled state, or a film may be continuously carbonized by being drawn out from the rolled polyimide film. The carbonization step is preferably performed under a vacuum atmosphere and under reduced pressure in an inert gas, and nitrogen can be suitably used as the inert gas. In the present specification, the carbonaceous polyimide film obtained by the carbonization step may be referred to as a carbonaceous film.
The carbonaceous film obtained by carbonizing the polyimide film is a film having a somewhat disturbed orientation as in the polyimide film. Since the carbonaceous thin film having a somewhat disturbed orientation is liable to discharge exhaust gas in a graphitization step described later, the foaming of the graphite sheet obtained by heat-treating (graphitizing) the carbonaceous thin film can be suppressed, and therefore, a graphite sheet excellent in thermal conductivity, surface properties and flexibility can be provided.
(graphitization step)
The graphitization step is a step of graphitizing the carbonaceous thin film obtained in the carbonization step by heat-treating the carbonaceous thin film at a temperature of 2400 ℃ or higher. The graphitization step may be referred to as a step of heat-treating the carbonaceous thin film to obtain a graphite sheet (a graphite sheet before rolling). In the graphitization step, the temperature (highest temperature) at which the carbonaceous thin film obtained in the carbonization step is heat-treated is preferably 2400 ℃ or higher, 2600 ℃ or higher, 2800 ℃ or higher, 2900 ℃ or higher, or 3000 ℃ or higher, for example. The upper limit of the maximum temperature is not particularly limited, but is preferably 3300 ℃ or lower, more preferably 3200 ℃ or lower. In the graphitization step, if the temperature (highest temperature) at which the carbonaceous thin film obtained in the carbonization step is heat-treated is 2400 ℃ or higher, there is an advantage that the thermal diffusivity of the obtained graphite sheet becomes good, and if it is 3300 ℃ or lower, there is an advantage that sublimation of the graphite member in the graphitization furnace can be suppressed. The graphitization step is performed under reduced pressure in an inert gas, and argon or helium may be suitably used as the inert gas.
In the graphitizing step, the rectangular carbonaceous film may be graphitized in a state of being laminated with the graphite sheet, the rolled carbonaceous film may be graphitized while being kept in a rolled state, or the film may be continuously graphitized by being drawn out from the rolled carbonaceous film.
(calendaring process)
The rolling step is a step of rolling the graphite sheet (the graphite sheet before rolling) obtained by the graphitization step. The rolling step may be referred to as a step of obtaining a rolled graphite sheet, and may be referred to as a compression step. The graphite sheet before rolling may have an excessive thickness which is unsuitable for implementation in a state of foaming due to the influence of exhaust gas or the like caused by graphitization, but the thickness of the graphite sheet can be adjusted and flexibility can be imparted by performing the rolling step. In the rolling step, the method of rolling the graphite sheet is not particularly limited, and examples thereof include a method of rolling using a metal roll or the like. The rolling step may be performed in a state where the produced graphite sheet is cooled to room temperature, or may be performed continuously with the graphitization process.
A polyimide film for a graphite sheet, which comprises an acid dianhydride component and a diamine component as raw materials, wherein the acid dianhydride component comprises 65 to 100 mol% of pyromellitic dianhydride, 0 to 35 mol% of at least one of 3,3', 4' -benzophenone tetracarboxylic dianhydride and 4,4' -oxydiphthalic anhydride in 100 mol% of the total acid dianhydride component, and the diamine component comprises 65 to 100 mol% of 4,4' -diaminodiphenyl ether, 0 to 35 mol% of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane in 100 mol% of the total diamine component, and the total content of the 3,3', 4' -benzophenone tetracarboxylic dianhydride, the 4,4' -oxydiphthalic anhydride and the 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane is 1 to 35 mol% relative to the total amount of the acid dianhydride component and the diamine component of 200 mol%.
The polyimide film for a graphite sheet according to [ 1 ], wherein the acid dianhydride component contains 100 mol% of pyromellitic dianhydride, and the diamine component contains 65 to 99 mol% of 4,4' -diaminodiphenyl ether and 1 to 35 mol% of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane.
The polyimide film for a graphite sheet according to [ 1 ], wherein the diamine component comprises 100 mol% of 4,4 '-diaminodiphenyl ether, and the acid dianhydride component comprises 65 to 99 mol% of pyromellitic dianhydride, and 1 to 35 mol% of at least any one of 3,3',4 '-benzophenone tetracarboxylic dianhydride and 4,4' -oxydiphthalic anhydride.
The polyimide film for a graphite sheet according to [ 1 ], which has a thickness of 80 to 200. Mu.m.
[ 5 ] A graphite sheet comprising the polyimide film for a graphite sheet of [ 1 ] as a raw material.
The graphite flake of item [ 5 ], which has a thickness of 45 to 110. Mu.m.
A process for producing a graphite sheet, which comprises the step of heat-treating a polyimide film for a graphite sheet to 2400 ℃ or higher, wherein the polyimide film for a graphite sheet comprises an acid dianhydride component and a diamine component, the acid dianhydride component comprises 65 to 100 mol% of pyromellitic dianhydride, 0 to 35 mol% of at least one of 3,3', 4' -benzophenone tetracarboxylic dianhydride and 4,4' -oxydiphthalic anhydride, and the diamine component comprises 65 to 100 mol% of 4,4' -diaminodiphenyl ether, 0 to 35 mol% of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane, and the 3,3', 4' -benzophenone tetracarboxylic dianhydride, the 4,4' -oxydiphthalic anhydride and the 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane are contained in a total amount of 200 mol% relative to the total amount of the acid dianhydride component and the diamine component, the total amount of the 3,3', 4' -benzophenone tetracarboxylic dianhydride and the 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane being 1 to 35 mol%.
The method for producing a graphite sheet according to [ 7 ], wherein the acid dianhydride component contains 100 mol% of pyromellitic dianhydride and the diamine component contains 65 to 99 mol% of 4,4' -diaminodiphenyl ether and 1 to 35 mol% of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane.
The method for producing a graphite sheet according to [ 7 ], wherein the diamine component comprises 100 mol% of 4,4 '-diaminodiphenyl ether, and the acid dianhydride component comprises 65 to 99 mol% of pyromellitic dianhydride, and 1 to 35 mol% of at least any one of 3,3',4 '-benzophenone tetracarboxylic dianhydride and 4,4' -oxydiphthalic anhydride.
The method for producing a graphite flake as described in [ 10 ], wherein the thickness of the polyimide film for a graphite flake is 80 to 200. Mu.m.
The method for producing a graphite flake as described in [ 7 ], wherein the thickness of the obtained graphite flake is 45 to 110. Mu.m.
A process for producing a polyimide film, which comprises the step of polymerizing an acid dianhydride component comprising 65 to 100 mol% of pyromellitic dianhydride, 0 to 35 mol% of at least one of 3,3', 4' -benzophenone tetracarboxylic dianhydride and 4,4' -oxydiphthalic anhydride and a diamine component comprising 65 to 100 mol% of 4,4' -diaminodiphenyl ether, 0 to 35 mol% of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane, and 1 to 35 mol% of the total amount of 3,3', 4' -benzophenone tetracarboxylic dianhydride, 4' -oxydiphthalic anhydride and 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane, based on 100 mol% of the total amount of the acid dianhydride component and the diamine component.
The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and embodiments in which the technical means disclosed in the different embodiments are appropriately combined are also included in the technical scope of the present invention.
Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples.
Examples
The respective evaluation methods in the examples and comparative examples are described below.
< thickness of graphite sheet before Rolling >
The thickness of the graphite sheet before rolling was measured by the following method. In the graphite sheet before rolling, the thickness of 4 points at the corners and 1 point at the center of the graphite sheet was measured using a micrometer manufactured by Mitutoyo corporation. Here, the "1 central portion" means a portion of the obtained graphite sheet at the intersection point when the diagonal line is drawn from the measurement portion at 4 points in each corner to the measurement portion located at the diagonal line. Then, the average value of the obtained measured values of the thicknesses of a total of 5 portions (4 portions at the corner and 1 portion at the center) was used as the thickness of the graphite sheet before rolling. The 4 corner points are vertices of the rectangular graphite sheet before rolling, which is the object of measurement.
< surface Property of graphite sheet before Rolling >
The surface properties of the graphite sheet before rolling were evaluated based on whether or not surface peeling was observed in the graphite sheet before rolling. The graphite sheets according to the following evaluations a and B were evaluated as graphite sheets excellent in surface properties, and the graphite sheets according to the following evaluations C and D were evaluated as graphite sheets poor in surface properties.
The evaluation criteria were as follows.
A (excellent): the graphite flake was not found to have surface peeling as a whole, and even if the surface of the graphite flake was touched by hand, graphite powder did not adhere to the hand.
B (pass): the graphite powder was adhered to the hand when the surface of the graphite sheet was touched with the hand, although the surface peeling was not observed in the whole graphite sheet.
C (slightly bad): surface peeling was observed in a part of the graphite sheet.
D (bad): the graphite sheet was observed to have a surface peeling off as a whole, and the sheet-like shape could not be maintained.
Production rate of graphite sheet
The productivity of the graphite sheet was evaluated based on the ratio (GS thickness/PI thickness) of the thickness of the polyimide film before carbonization to the thickness of the graphite sheet before rolling measured by the method described in item < thickness of the graphite sheet before rolling > above. The calculation method of the GS thickness/PI thickness is as follows;
GS thickness/PI thickness = thickness of graphite sheet before calendaring/thickness of polyimide film.
The evaluation criteria were as follows.
A (excellent): GS thickness/PI thickness is 1.0 or less
B (pass): GS thickness/PI thickness exceeds 1.0 and is 3.0 or less
C (bad): the GS thickness/PI thickness exceeds 3.0.
< thickness of rolled graphite sheet >
The thickness of the graphite sheet after the rolling was measured by the following method. In the rolled graphite sheet, thicknesses of 4 points at the corners and 1 point at the center of the graphite sheet were measured using a micrometer manufactured by Mitutoyo corporation. Here, the "1 central portion" means a portion of the obtained graphite sheet at the intersection point when the diagonal line is drawn from the measurement portion at 4 points of each corner to the measurement portion located at the diagonal line. Then, the average value of the obtained measured values of the thicknesses of a total of 5 portions (4 portions at the corner and 1 portion at the center) was set as the thickness of the graphite sheet after the rolling. The 4 corner portions are vertices of the rectangular rolled graphite sheet to be measured.
< thermal diffusivity of rolled graphite sheet >)
The thermal diffusivity of the rolled graphite sheet was measured by the following method. The thermal diffusivity of a sample of rolled graphite sheet cut into square shapes of 30mm×30mm was measured under the condition of 75Hz at 25 ℃ using bethen co., "ThermoWave Analyzer TA3" by ltd. The sample was produced by punching out the central portion of the rolled graphite sheet as the object of measurement with a thomson knife. Here, the "central portion" refers to a portion that is central in the width direction and is also central in the longitudinal direction in the rolled graphite sheet.
< Density of rolled graphite sheet >
The density of the graphite flake after the extrusion was measured by the following method. The center portion of the rolled graphite sheet was punched out into a square shape of 30mm×30mm to obtain a sample. Then, the weight of the above sample was measured. Based on the measured value of the weight and the thickness of the sample measured by the method described in item < thickness of the rolled graphite sheet >, the density of the rolled graphite sheet was calculated by the following formula.
Density of the rolled graphite sheet = weight of the rolled graphite sheet/(area of the rolled graphite sheet x thickness of the rolled graphite sheet).
Flexibility of the rolled graphite sheet
The flexibility of the rolled graphite sheet was evaluated based on the following evaluation criteria.
A (good): no wrinkles were visible even when wound around a rod of 1mm diameter.
B (slightly better): when wound around a rod having a diameter of 1mm, wrinkles were observed at the end, but no cracks were observed. Further, even when wound around a rod having a diameter of 10mm, wrinkles were not observed.
C (pass): when wound around a rod having a diameter of 10mm, wrinkles were observed, but no cracks were observed.
D (bad): when wound around a rod having a diameter of 10mm, cracks were generated.
Comparative example 1
< manufacturing of polyimide film >
A polyamide acid solution containing 18.5% by weight of a polyamide acid was obtained by dissolving 100 mol% of pyromellitic dianhydride (PMDA) as an acid dianhydride component in a dimethylformamide solution containing 100 mol% of 4,4' -diaminodiphenyl ether (ODA) as a diamine component and polymerizing the diamine component and the acid dianhydride component. Calcium hydrogen phosphate (average particle diameter 2.2 μm) was added as inorganic particles to the obtained polyamic acid solution so that the concentration of the calcium hydrogen phosphate became 0.04% by weight with respect to the solid content of the polyamic acid. While cooling the solution, an imidization catalyst comprising 1 equivalent of acetic anhydride, 1 equivalent of isoquinoline and 1 equivalent of dimethylformamide was added to the carboxylic acid group contained in the polyamic acid, and deaeration was performed, thereby obtaining a solution (mixed solution) comprising the polyamic acid.
Then, the above mixed solution was applied to an aluminum foil so that the thickness thereof after drying was 125. Mu.m, 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. The drying conditions were as follows. First, the mixed solution layer on the aluminum foil was dried at 120 ℃ for 400 seconds by a hot air oven to prepare a self-supporting gel film. The gel film was peeled off from the aluminum foil and fixed to a frame. Further, the gel film was dried by heating it stepwise with a hot air oven at 120℃for 50 seconds, at 275℃for 66 seconds, at 400℃for 70 seconds, at 450℃for 85 seconds, and with a far infrared heater at 460℃for 35 seconds, to prepare a polyimide film (A) having a thickness of 125. Mu.m.
< manufacturing of graphite sheet >
Polyimide film (a) cut into 200mm by 200mm was sandwiched between graphite sheets 220mm by 220mm in size (1 polyimide film and 1 graphite sheet were alternately laminated), to obtain a laminate. The laminate was set in a carbonizing apparatus (carbonizing apparatus manufactured by Kagaku Tian Jiyan Co., ltd.) (heating space). The heating space in the carbonization apparatus provided with the laminate was heated to 600 ℃ at a heating rate of 0.4 ℃/min under a vacuum atmosphere, and then kept at 600 ℃ for 1 hour. Then, the heating space in the carbonization apparatus was heated to 1000 ℃ at a heating rate of 0.4 ℃/min, and then the laminate (polyimide film in the laminate) was subjected to heat treatment (carbonization) at 1000 ℃ for 30 minutes to obtain a carbonaceous film.
The obtained carbonaceous film was cooled to room temperature (23 ℃) and rolled into a roll having an inner diameter of 100mm, to obtain a rolled carbonaceous film. The rolled carbonaceous film was placed on a hearth of a graphitization furnace (graphitization furnace manufactured by bin Tian Jiyan corporation) so that the width direction was perpendicular, and the temperature was raised to 2900 ℃ (graphitization maximum temperature) at a temperature raising rate of 2 ℃/min under argon atmosphere in a high temperature region of more than 2200 ℃ under reduced pressure in a temperature region of 2200 ℃ and then maintained at 2900 ℃ for 30 minutes, whereby a graphitized film (a graphite sheet before rolling) was produced. The thickness, surface properties and productivity of the resulting graphite sheet before rolling were measured and evaluated. The results are shown in Table 1.
The obtained graphitized film was cooled to room temperature, and a 2-ton precision roll press (gap type) manufactured by ltd was used to perform a rolling treatment to obtain graphite flakes (rolled graphite flakes). The thickness, thermal diffusivity, density and flexibility of the resulting rolled graphite sheet were measured and evaluated. The results are shown in Table 1.
Examples 1 to 13 and comparative examples 1 to 3
A polyimide film was produced in the same manner as in comparative example 1 except that the composition of the acid dianhydride component and/or the diamine component and the addition amounts thereof were changed to those shown in table 1, and the polyimide film was subjected to heat treatment to produce a graphite sheet. The physical properties of the produced graphite sheet were measured and evaluated in the same manner as in comparative example 1, and the results are shown in table 1.
Examples 14 to 18
A polyimide film was produced in the same manner as in comparative example 1 except that the composition of the acid dianhydride component and/or the diamine component and the addition amount thereof were changed to the compositions and amounts shown in table 1, and the thickness of the polyimide film was further set to the thickness shown in table 1, and the polyimide film was subjected to heat treatment to produce a graphite sheet. The film formation time of the polyimide film and the temperature rise time of the graphitization step were adjusted in proportion to the thickness. For example, in the case of producing a polyimide film having a thickness of 80 μm, the film formation time (drying time) of the polyimide film and the temperature rise time of the graphitization step are set to a length of 0.64 (80/125) times as long as in the case of producing a polyimide film having a thickness of 125 μm. The physical properties of the produced graphite sheet were measured and evaluated in the same manner as in comparative example 1, and the results are shown in table 1.
TABLE 1
As is clear from table 1, when the polyimide film contains 65 to 100 mol% of PMDA, 0 to 35 mol% of at least one of BTDA and ODPA as an acid dianhydride component, or 65 to 100 mol% of ODA and 0 to 35 mol% of BAPP as a diamine component, and the total content of BTDA, ODPA and BAPP is 1 to 35 mol% relative to the total amount of the acid dianhydride component and the diamine component, the obtained graphite sheet has a sufficiently thin thickness before rolling and has excellent surface properties with less surface peeling (examples 1 to 18). In addition, it is also known that the heat diffusion after the compression molding is excellent, the flexibility is excellent, and the density is also high. That is, the polyimide film according to one embodiment of the present invention shows that a graphite sheet excellent in thermal conductivity, surface properties and flexibility can be obtained with good productivity. In addition, the thickness of the graphite sheet before rolling was sufficiently thin, and therefore, it was shown that productivity was excellent and density was also excellent.
On the other hand, as is clear from the results of comparative example 1, when PMDA was used alone as the acid dianhydride component and ODA was used as the diamine component, that is, when the polyimide film did not contain any of BTDA, ODPA, and BAPP, the surface peeling of the obtained graphite sheet was large, the surface properties were poor, the thickness before rolling was too thick, and the productivity was low. Further, as is clear from the results of comparative example 2, when BPDA was used as an acid dianhydride component instead of BTDA and ODPA, the surface peeling of the obtained graphite sheet was also large, the surface properties were poor, and the thickness before rolling was too thick, and the productivity was low. The surface peeling of the graphite sheet before rolling of the graphite sheet of comparative example 3 was significantly poor, the sheet-like shape could not be maintained, and the sheet-like shape could not be used in the rolling step and the physical properties after rolling could not be measured.
Industrial applicability
Since the graphite sheet using the polyimide film according to one embodiment of the present invention as a raw material is excellent in heat conductivity, surface properties and flexibility, the polyimide film can be suitably used as a heat radiating member of an electronic device, particularly a thin electronic device.
Claims (12)
1. A polyimide film for graphite sheet, which is a polyimide film using acid dianhydride component and diamine component as raw materials,
the acid dianhydride component contains 65 to 100 mol% of pyromellitic dianhydride, 0 to 35 mol% of at least any one of 3,3', 4' -benzophenone tetracarboxylic dianhydride and 4,4' -oxydiphthalic anhydride in 100 mol% of the total amount of the acid dianhydride components,
the diamine component comprises 65 to 100 mol% of 4,4' -diaminodiphenyl ether and 0 to 35 mol% of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane in 100 mol% of the total amount of the diamine component,
the total content of the 3,3', 4' -benzophenone tetracarboxylic dianhydride, the 4,4' -oxydiphthalic anhydride and the 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane is 1 to 35 mol% based on 200 mol% of the total amount of the acid dianhydride component and the diamine component.
2. The polyimide film for graphite sheets according to claim 1, wherein the acid dianhydride component contains 100 mol% of pyromellitic dianhydride and the diamine component contains 65 to 99 mol% of 4,4' -diaminodiphenyl ether and 1 to 35 mol% of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane.
3. The polyimide film for graphite sheets according to claim 1, wherein the diamine component comprises 100 mol% of 4,4 '-diaminodiphenyl ether, and the acid dianhydride component comprises 65 to 99 mol% of pyromellitic dianhydride, and at least one of 3,3',4 '-benzophenone tetracarboxylic dianhydride and 4,4' -oxydiphthalic anhydride is 1 to 35 mol%.
4. The polyimide film for graphite sheet according to claim 1, which has a thickness of 80 to 200. Mu.m.
5. A graphite sheet comprising the polyimide film for graphite sheet according to claim 1 as a raw material.
6. The graphite flake of claim 5, having a thickness of 45 to 110 μm.
7. A method for producing a graphite sheet, comprising a step of heat-treating a polyimide film for a graphite sheet to 2400 ℃ or higher,
the polyimide film for the graphite sheet is a polyimide film which takes acid dianhydride component and diamine component as raw materials,
The acid dianhydride component contains 65 to 100 mol% of pyromellitic dianhydride, 0 to 35 mol% of at least any one of 3,3', 4' -benzophenone tetracarboxylic dianhydride and 4,4' -oxydiphthalic anhydride in 100 mol% of the total amount of the acid dianhydride components,
the diamine component comprises 65 to 100 mol% of 4,4' -diaminodiphenyl ether and 0 to 35 mol% of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane in 100 mol% of the total amount of the diamine component,
the total content of the 3,3', 4' -benzophenone tetracarboxylic dianhydride, the 4,4' -oxydiphthalic anhydride and the 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane is 1 to 35 mol% based on 200 mol% of the total amount of the acid dianhydride component and the diamine component.
8. The method for producing a graphite sheet as set forth in claim 7, wherein the acid dianhydride component contains 100 mol% of pyromellitic dianhydride, and the diamine component contains 65 to 99 mol% of 4,4' -diaminodiphenyl ether and 1 to 35 mol% of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane.
9. The method for producing a graphite sheet as set forth in claim 7, wherein the diamine component comprises 100 mol% of 4,4 '-diaminodiphenyl ether, and the acid dianhydride component comprises 65 to 99 mol% of pyromellitic dianhydride, and at least one of 3,3',4 '-benzophenone tetracarboxylic dianhydride and 4,4' -oxydiphthalic anhydride is 1 to 35 mol%.
10. The method for producing a graphite sheet as defined in claim 7, wherein the thickness of the polyimide film for a graphite sheet is 80 to 200. Mu.m.
11. The method for producing a graphite sheet as set forth in claim 7, wherein the thickness of the resulting graphite sheet is 45 to 110. Mu.m.
12. A method for producing a polyimide film, comprising a step of polymerizing an acid dianhydride component and a diamine component,
the acid dianhydride component contains 65 to 100 mol% of pyromellitic dianhydride, 0 to 35 mol% of at least any one of 3,3', 4' -benzophenone tetracarboxylic dianhydride and 4,4' -oxydiphthalic anhydride in 100 mol% of the total amount of the acid dianhydride components,
the diamine component comprises 65 to 100 mol% of 4,4' -diaminodiphenyl ether and 0 to 35 mol% of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane in 100 mol% of the total amount of the diamine component,
the total content of the 3,3', 4' -benzophenone tetracarboxylic dianhydride, the 4,4' -oxydiphthalic anhydride and the 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane is 1 to 35 mol% based on 200 mol% of the total amount of the acid dianhydride component and the diamine component.
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