JP2003071966A - Insulated graphite sheet and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a graphite sheet excellent in insulating properties and capable of being manufactured at a low cost. SOLUTION: The low cost graphite sheet excellent in insulating properties is obtained by directly coating the surface of a graphite sheet with a polyimide resin or a precursor thereof and drying the coated graphite sheet to form a coating layer with a thickness of 0.1 to <10 μm.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a graphite sheet having an insulated surface and a method for producing the same.

[0002]

2. Description of the Related Art Graphite sheets are widely used as electrodes and heat conductive materials because of their heat resistance and high electric conductivity. In addition to natural methods, as methods for artificially creating, Japanese Patent No. 1566176, JP-A-2000-169125, JP-A-2000-247619 and the like are known. Specifically, polyimide-based films, polyamide-based films, polybenzimidazole-based films, etc. can be used in an inert gas at room temperature to
It is obtained by firing in a stepwise manner at a high temperature of 500 ° C. or higher, and then it is said that it is preferable to roll with a roll or the like in order to develop flexibility and mechanical strength.

However, since the surface of these graphite sheets is not insulated, when they are used for heat dissipation of electronic equipment, due to their high electrical conductivity characteristics, electrical short circuits between electronic parts occur. Occurs.

Therefore, for example, in Japanese Patent Laid-Open No. 11-268976,
A method has been devised mainly for laminating a polyester film on the surface of a graphite sheet by thermocompression to insulate it, but this method has poor adhesion to the graphite sheet,
There is a defect that voids are generated between the graphite sheet and the polyester film, which further reduces the heat transfer efficiency. Also,
In order to solve this problem, there is an attempt to improve the adhesion by forming an inorganic material on the surface of the graphite sheet by a method called sputtering, but the process is complicated, the manufacturing cost is high, and it is not suitable for practical use. . Since the heat resistance of the polyester film itself is low, the heat resistance characteristics of the graphite sheet cannot be utilized. Further, a method of dissolving a polyester film in a solvent and applying it is also exemplified, but the production efficiency is poor because it is necessary to form a film of an inorganic material as described above. Further, in JP-A-2000-247740, a method of chemically insulating the surface of a graphite sheet with fluorine or chlorine has been devised, and although these have insulation and heat resistance,
These also have drawbacks such as plasma treatment, which requires expensive equipment, high manufacturing cost, and difficulty in continuous work, and is not preferable in industry.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems.

[0006]

The present inventors have completed the present invention as a result of intensive studies. That is, the present invention provides: (1) a graphite sheet having a surface coated with a resin, wherein the resin is a polyimide resin (2) The coating thickness of the polyimide resin is 0.1. 10 μm or more
(1) The graphite sheet according to (1), characterized in that it is less than μm (3) The polyimide resin or its precursor is directly applied to the surface of the graphite sheet and then dried, (1) or (2) To a method for manufacturing a graphite sheet.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The polyimide-based resin used in the present invention is not particularly limited as long as it is a resin containing polyimide and / or polyamide-imide as a main component so as not to impair the heat resistance of the graphite sheet. Depending on the temperature condition, a cheaper other polymer resin and polyimide and / or polyamide-imide may be appropriately mixed so as to have heat resistance at that temperature. Diamine and aromatic tetracarboxylic dianhydride, which are raw materials of polyimide and / or polyamideimide, are specifically m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, and m-aminobenzylamine as diamines. , P-aminobenzylamine, bis (3-aminophenyl) sulfide, (3-aminophenyl) (4-
Aminophenyl) sulfide, bis (4-aminophenyl) sulfide, bis (3-aminophenyl) sulfoxide, (3-aminophenyl) (4-aminophenyl)
Sulfoxide, bis (3-aminophenyl) sulfone,
(3-Aminophenyl) (4-aminophenyl) sulfone, bis (4aminophenyl) sulfone, 3,3′-diaminobenzophenone, 3,4′-diaminobenzophenone, 4,4′-diaminobenzophenone, 3,3 ′ −
Diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane,
4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, bis [4- (3-aminophenoxy) phenyl] methane, bis [4- (4-aminophenoxy)
Phenyl] methane, 1,1-bis [4- (3-aminophenoxy) phenyl] ethane, 1,1-bis [4- (4
-Aminophenoxy) phenyl] ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] ethane,
1,2-bis [4- (4-aminophenoxy) phenyl] ethane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) Phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] butane,
2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl]- 1,1,1,3,3,3-hexafluoropropane, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene,
1,4'-bis (4-aminophenoxy) benzene,
4,4'-bis (3-aminophenoxy) biphenyl,
4,4'-bis (4-aminophenoxy) biphenyl,
Bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl]
Sulfide, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] sulfoxide, bis [4- (aminophenoxy) phenyl] sulfoxide, bis [4- (3-amino) Phenoxy) phenyl] sulfone, bis [4- (4
-Aminophenoxy) phenyl] sulfone, bis [4-
(3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether,
1,4-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 4,4′-bis [3-
(4-Aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [3- (3-aminophenoxy)
Benzoyl] diphenyl ether, 4,4′-bis [4
-(4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, bis [4- {4- (4-Aminophenoxy) phenoxy} phenyl] sulfone, 1,4-bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) Examples include -α, α-dimethylbenzyl] benzene and the like, which may be used alone or in combination of two or more kinds. The amount replaced by the amine compound is
Usually, it is in the range of 0 to 50 mol% of the above-mentioned diamine.

As the substances which may be used in combination with the above-mentioned tetracarboxylic dianhydride, for example, ethylenetetracarboxylic dianhydride, butanetetracarboxylic dianhydride, cyclopentanecarboxylic dianhydride, pyromellitic dianhydride. , 2,2 ', 3,3'-benzophenone tetracarboxylic dianhydride, 3,3', 4,4'-benzophenone tetracarboxylic dianhydride, 2,2 ', 3,3'-biphenyltetra Carboxylic dianhydride, 3,3 ', 4,4'-
Biphenyltetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride,
Bis (3,4-dicarboxyphenyl) ether dianhydride, bis (2,3-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenylsulfone) dianhydride, bis (2,3 -Dicarboxyphenyl)
Sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 4,4 ′-(p-phenylenedioxy) ) Diphthalic dianhydride, 4,4 '-(m
-Phenylenedioxy) diphthalic acid dianhydride, 2,3
6,7-naphthalenetetracarboxylic dianhydride, 1,
4,5,8-naphthalenetetracarboxylic dianhydride,
1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2 , 3,6,7-anthracene tetracarboxylic acid dianhydride, 1,2,7,8-phenanthrene tetracarboxylic acid dianhydride and the like can be mentioned, and they can be used alone or in combination of two or more kinds. The substitution amount of the tetracarboxylic acid used in combination is usually in the range of 0 to 50 mol% of the above-mentioned tetracarboxylic acid. A dicarboxylic acid anhydride may be added for the purpose of sealing the polymer end of the present invention.

The dicarboxylic acid anhydride used is
Phthalic anhydride, 2,3-benzophenone dicarboxylic acid anhydride, 3,4-benzophenone dicarboxylic acid anhydride,
2,3-dicarboxyphenyl phenyl ether anhydride, 2,3-biphenyl dicarboxylic acid anhydride, 3,4-
Biphenyl dicarboxylic acid anhydride, 2,3-dicarboxyphenyl phenyl sulfone anhydride, 3,4-dicarboxyphenyl phenyl sulfone anhydride, 2,3-dicarboxyphenyl phenyl sulfide anhydride, 1,2-naphthalenedicarbobon Acid anhydride, 2,3-naphthalenedicarboxylic acid anhydride, 1,8-naphthalenedicarboxylic acid anhydride, 1,2-anthracene dicarboxylic acid anhydride, 2,3
-Anthracene dicarboxylic acid anhydride and 1,9-anthracene dicarboxylic acid anhydride. These dicarboxylic acid anhydrides may be substituted with groups that are not reactive with amines or dicarboxylic acid anhydrides. The amount of the dicarboxylic acid anhydride added is usually 0.00 based on 100 mol of the total amount of the main raw material diamine and tetracarboxylic acid dianhydride.
The range is 1 to 0.5 mol, preferably 0.005 to 0.
It is in the range of 25 mol.

Similarly, a monoamine may be added for the purpose of blocking the polymer end. Examples of the monoamine used include the following. For example, aniline,
o-toluidine, m-toluidine, p-toluidine,
2,3-xylidine, 2,4-xylidine, 2,5-xylidine, 2,6-xylidine, 3,4-xylidine,
3,5-xylidine, o-chloroaniline, m-chloroaniline, p-chloroaniline, o-nitroaniline,
o-bromoaniline, m-bromoaniline, o-nitroaniline, m-nitroaniline, p-nitroaniline,
o-aminophenol, m-aminophenol, p-aminophenol, o-anilidine, m-anilidine, p
-Anilidine, o-phenetidine, m-phenetidine,
p-phenetidine, o-aminobenzaldehyde, m-
Aminobenzaldehyde, p-aminobenzaldehyde, o-aminobenzonitrile, m-aminobenzonitrile, p-aminobenzonitrile, 2-aminobiphenyl, 3-aminobiphenyl, 4-aminobiphenyl, 2
-Aminophenol phenyl ether, 3-aminophenol phenyl ether, 4-aminophenol phenyl ether, 2-aminobenzophenone, 3-aminobenzophenone, 4-aminobenzophenone, 2-aminophenol phenyl sulfide, 3-aminophenol phenyl sulfide, 4 -Aminophenol phenyl sulfide, 2-aminophenol phenyl sulfone, 3
-Aminophenol phenyl sulfone, 4-aminophenol phenyl sulfone, α-naphthylamine, β-naphthylamine, 1-amino-2-naphthol, 2-amino-1-naphthol, 4-amino-1-naphthol, 5
-Amino-1-naphthol, 5-amino-1-naphthol, 5-amino-2-naphthol, 7-amino-2-naphthol, 8-amino-2-naphthol, 1-aminoanthracene, 2-aminoanthracene, 9 -Aminoanthracene and the like.

These monoamines may be used alone or in combination of two or more. The amount of monoamine added is
Usually, it is in the range of 0.001 to 0.5 mol, and preferably in the range of 0.005 to 0.25 mol, based on 100 mol of the total of the main raw material, diamine and tetracarboxylic dianhydride. The thickness of the polyimide resin is 0.1 μm or more.
The thickness is preferably less than 10 μm, and is preferably in this range from the viewpoint of satisfying both insulation performance and thermal conductivity, and more preferably 1 μm or more and 5 μm or less. As a method of coating the polyimide resin, it is preferable to directly apply the resin to the surface of the graphite sheet. The reason for this is that the graphite sheet surface generally has irregularities, it is difficult to completely fill the irregularities by the method of laminating resin, and the adhesion is weak and voids are generated at the interface. To prevent this, it is preferable to apply the resin directly to the graphite sheet. As a method of coating, it is preferable to use the one in which the resin is first dissolved in a solvent or to use the precursor solution of the resin in order to make the finished film thickness uniform. In this case, a step of evaporating the solvent is necessary. As a coating method, other general coating methods such as dip coating, spray coating, roll coating, die coating, comma coating, bar coating, curtain coating can be applied, but a relatively inexpensive and uniform coating film can be applied. To obtain it, it is preferable to repeatedly apply it by dip coating or spray coating. Further, as a drying method, a general hot air dryer or an IR heater furnace is used, and there is no particular limitation such as in air or in an inert gas.

[0012]

[Examples] Example 1, with 1.00 mol of 3-bis (3-aminophenoxy) benzene,
Weigh 0.975 mol of 3,3 ', 4,4'-biphenyltetracarboxylic acid and add N, N'-dimethylacetamide at a solid concentration.
It was added so as to be 7 wt% and dissolved by stirring at 50 ° C for 15 hours to obtain a polyamic acid solution as a precursor of polyimide. Using a spray gun with a diameter of 0.8 mm, this was placed on a graphite sheet surface with a thickness of about 25 μm at a distance from the sheet of 200 mm, divided into 6 times, and the thickness after drying was 2 μm. It was applied to both sides. After that, 80 ℃ for 15 minutes, 200 ℃ for 15 minutes, 280 ℃
After drying for 15 minutes, a graphite sheet insulated with polyimide was obtained. The surface resistance of this sheet was measured according to the test method ASTM-D-257. As a result, it had a resistance of 10 ⁶ Ω or more and was completely insulated.

[0013]

As described above, according to the present invention, the surface of the graphite sheet can be easily insulated, and its heat resistance and thermal conductivity are not impaired, so that it has high industrial utility value.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masataka Kobayashi             580-32 Nagaura, Sodegaura-shi, Chiba Mitsui Chemicals, Inc.             Inside the company (72) Inventor Masayuki Tashiro             580-32 Nagaura, Sodegaura-shi, Chiba Mitsui Chemicals, Inc.             Inside the company F-term (reference) 4F100 AA37B AD11B AK49A BA02                       BA03 BA06 BA25B EH462                       EJ862 GB41 JG04 JJ01                       JJ03 YY00B

Claims (3)

[Claims] 1. A graphite sheet, the surface of which is coated with a resin, wherein the resin is a polyimide resin. 2. The coating thickness of the polyimide resin is 0.1 μm.
The graphite sheet according to claim 1, wherein the graphite sheet has a thickness of 10 μm or more. 3. The method for producing a graphite sheet according to claim 1, wherein the polyimide resin or its precursor is directly applied to the surface of the graphite sheet and then dried.