JP2003286018A - Carbon film and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carbon film having a sufficiently large coefficient of separation and an improved transmission rate compared to a conventional material and to provide a method for manufacturing the film. <P>SOLUTION: The carbon film is obtained by applying a polyamic acid expressed by general formula (3) on the surface of a porous substrate, heating and drying the substrate to form a precursor of the carbon film and thermally decomposing the precursor in an oxygen inactive atmosphere. The compound expressed by general formula (3) is a precursor of polyimide resin expressed by general formula (1). In the formulae, X represents a 2-27C tetravalent group in aliphatic groups, alicyclic groups, monocyclic aromatic groups or the like, n represents an integer from 5 to 10,000, Y is expressed by general formula (2), wherein at least one of phenylene groups constituting the main chain skeleton is m-phenylene group, Z represents a direct bond, -O-, -CO- or the like, m represents an integer from 1 to 3, and each of R<SB>1-4</SB>and R'<SB>1-4</SB>represents a phenyl group, 4-phenylphenyl group, phenoxy group, 4-phenylphenoxy group or the like. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a carbon membrane used for separating and recovering a specific gas from a gas mixture by utilizing a molecular sieving function of pores of a carbon material.

[0002]

Various methods such as a liquefaction distillation method, an adsorption method and an absorption method are known as separation methods for separating and recovering a specific gas from a gas mixture and effectively using it.
All of these methods are disadvantageous in terms of energy because they involve a phase change. On the other hand, the membrane separation method is highly energy-saving because it exhibits high separation characteristics by simply using the difference in concentration or the difference in pressure as a driving force, and therefore, research is actively conducted on how to form a membrane having excellent permeation separation performance. Has been done.

In particular, a carbon film obtained by thermally decomposing and carbonizing a polymer material formed into a film at a high temperature has excellent heat resistance, and has more defects during film formation than a ceramic film or a zeolite film. Since it is unlikely to occur, it is currently attracting a lot of attention, and research is becoming active.

As an example of such a carbon film, Japanese Unexamined Patent Publication No.
-11933, JP-A-4-193334,
Japanese Unexamined Patent Publication No. 5-22036 discloses a carbonized film obtained by carbonizing an asymmetric hollow fiber film made of aromatic polyimide. Further, in Japanese Patent No. 3111196, a gas obtained by molding a cardo type polymer into a predetermined separation membrane shape to form a separation membrane precursor and heating the separation membrane precursor in an anaerobic atmosphere for carbonization. A separating carbonized membrane is disclosed.

Furthermore, Japanese Laid-Open Patent Publication No. 10-52629 is characterized in that a liquid thermosetting resin is applied to the surface of a ceramic porous body to form a polymer film, and then heat treatment is performed in a non-oxidizing atmosphere. A method for producing a molecular sieving carbon film is disclosed. Further, as a polyimide resin that is a precursor of a carbon film, the following structural formula (6) (H. Sudaet.al, J. Phy
s.Chem.B 101,3988-3994 (1997)) and the following structural formula (7)
(J. Hayashi et.al, Journal of Membrane Science 124,
243-251 (1997)) is known.

[Chemical 9]

[Chemical 10]

[0006]

In general, when the separation membrane as described above is used for selective permeation of gas or the like, the permeation rate becomes smaller if the separation coefficient is increased. The separation coefficient and the permeation rate of the carbon membrane are controlled by the decomposition conditions of the resin that is the precursor of the carbon membrane, etc.
At present, it is hard to say that the separation coefficient and the permeation rate are compatible with each other at a sufficiently satisfactory level.

The present invention has been made in view of such conventional circumstances, and an object of the present invention is to provide a carbon film having a sufficiently large separation coefficient and an improved permeation rate as compared with the conventional one. And to provide a manufacturing method thereof.

[0008]

Means for Solving the Problems According to the present invention, a polyimide resin whose repeating unit is represented by the following general formula (1) (wherein, X is an aliphatic group having 2 to 27 carbon atoms, a cyclic aliphatic group) A tetravalent group selected from the group consisting of an aromatic group, a monocyclic aromatic group, a condensed polycyclic aromatic group, and a non-condensed polycyclic aromatic group in which aromatic groups are connected to each other directly or by a bridging member. And n represents an integer of 5 to 10000, Y is represented by the following general formula (2), and in the general formula (2), at least one of the phenylene groups forming the main chain skeleton is m. −
It is a phenylene group, Z is a direct bond, -O-, -CO-,-.
_{S -, - SO 2 -,} - CH 2 -, - C (CH 3) 2 - or -
C (CF _{3) 2} - indicates, m is an integer of 1 to 3, also, R _1-4 and R _'1-4 may, -H, -F, -Cl, -B
_{r, -I, -CN, -CH 3} , -CF 3, -OCH 3,
A phenyl group, a 4-phenylphenyl group, a phenoxy group or a 4-phenylphenoxy group, and R _1-4 and R ′ _{1 -4}
Are all the same or different, and only some of them may be the same), and are polyamic acids represented by the following general formula (3) (wherein X and Y are the same). Is the same group as above) is applied to the surface of the porous substrate, heated and dried to form a precursor of the carbon film, and the precursor is thermally decomposed in an oxygen-inert atmosphere. A carbon film is provided.

[Chemical 11]

[Chemical 12]

[Chemical 13]

Further, according to the present invention, a polyimide resin whose repeating unit is represented by the following general formula (1) (provided that
In the formula, X is an aliphatic group having 2 to 27 carbon atoms, a cycloaliphatic group, a monocyclic aromatic group, a condensed polycyclic aromatic group, or an aromatic group, which is directly or cross-linked with each other. Represents a tetravalent group selected from the group consisting of non-fused polycyclic aromatic groups, and n is 5 to 5
Represents an integer of 10000, Y is represented by the following general formula (2), and in the general formula (2), at least one of the phenylene groups forming the main chain skeleton is an m-phenylene group, and Z is a direct bond. , -O-, -CO-, -S-, -SO
_{2 -, - CH 2 -,} - C (CH 3) 2 - or -C (CF _{3) 2}
-, M is an integer of 1 to 3, and R _1-4 and R ' _1-4 are -H, -F, -Cl, -Br, -I, -C.
_{N, -CH 3, -CF 3,} -OCH 3, phenyl, 4
A phenylphenyl group, a phenoxy group or a 4-phenylphenoxy group, R _1-4 and R ′ _1-4 may all be the same or different, and only a part thereof may be the same. Of a polyamic acid represented by the following general formula (3) (wherein X and Y represent the same groups as described above), which is a precursor of Provided is a method for producing a carbon film, which comprises forming a carbon film precursor and thermally decomposing the precursor in an oxygen-inert atmosphere.

[Chemical 14]

[Chemical 15]

[Chemical 16]

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the present invention relates to carbon.
In the formation of the film precursor, the repeating unit has the following general formula
Polyimide resin represented by (1) (where X is charcoal)
Aliphatic group having 2 to 27 primes, cycloaliphatic group, monocyclic aromatic group
Groups, fused polycyclic aromatic groups, and aromatic groups directly or crosslinked
Consisting of non-fused polycyclic aromatic groups linked together by members
A tetravalent group selected from the group
Represents the integer, and Y is represented by the following general formula (2).
In general formula (2), phenylene forming the main chain skeleton
At least one of the groups is an m-phenylene group, and Z
Is a direct connection, -O-, -CO-, -S-, -SO₂-, -C
H₂-, -C (CH₃)₂-Or-C (CF₃)₂Indicates −
, M represents an integer of 1 to 3, and R_1-4And R '_1-4
Is -H, -F, -Cl, -Br, -I, -CN, -C.
H₃ , -CF₃ , -OCH ₃, Phenyl group, 4-phenyl
Ruphenyl group, phenoxy group or 4-phenylphenoxy
R group_1-4And R '_1-4Are all the same,
They may be different, and only some of them are the same
The precursor represented by the following general formula (3)
Liamic acid (wherein X and Y represent the same groups as described above) is used.
The main feature is that it is used.

[Chemical 17]

[Chemical 18]

[Chemical 19]

As a result of the inventors of the present invention having conducted a study on a polymer material which becomes a precursor of a carbon film, when a polyimide resin having the above-mentioned structure is used for forming the precursor, the separation coefficient is increased. It was found that a carbon film having a high permeation rate can be obtained. It is considered that this is because the polyimide resin has a layered structure which is bulky as compared with that which has been conventionally used as a precursor for a carbon film, and also has a high degree of flexibility and can easily obtain a good film formation state.

Among the polyimide resins represented by the general formula (1), those represented by the following structural formulas (4) and (5) are particularly preferably used in the present invention. be able to.

[Chemical 20]

[Chemical 21]

A carbon film obtained by using these polyimide resins for forming a precursor is higher than a conventional carbon film obtained by using a polyimide resin represented by the following structural formulas (6) and (7), for example. Thus, even with the same separation coefficient, it shows a higher permeation rate.

[Chemical formula 22]

[Chemical formula 23]

The polyamic acid and the polyimide resin according to the present invention may be manufactured by any method. The polyamic acid and the polyimide resin according to the present invention include at least a diamine represented by the following general formula (8) (in the general formula (8), at least a phenylene group bonding an amino group and Z and / or Z and Z). One is an m-phenylene group, Z is a direct bond, -O-, -CO-, -S-,
_{-SO 2 -, - CH 2 -} , - C (CH 3) 2 - or -C (C
F ₃ ) ₂ −, m is an integer of 1 to 3, and R is
_1-4 and _R'1-4 are -H, -F, -Cl, -Br,-.
_{I, -CN, -CH 3, -CF} 3, -OCH 3, phenyl, 4-phenylphenyl group, a phenoxy group or a 4-
A phenylphenoxy group, R _1-4 and R ′ _1-4 may all be the same or different, and only a part thereof may be the same) and the following general formula (9) Represented tetracarboxylic dianhydrides (wherein X is 2 to 2 carbon atoms)
27 aliphatic groups, cycloaliphatic groups, monocyclic aromatic groups, condensed polycyclic aromatic groups, and non-condensed polycyclic aromatic groups in which aromatic groups are connected to each other directly or by a crosslinking member A tetravalent group selected from the group consisting of the following) is used as the monomer.

[Chemical formula 24]

[Chemical 25]

The diamines used in the production of the polyamic acid and the polyimide resin according to the present invention are represented by the general formula (8)
At least one compound represented by Specifically, but not limited to, for example, in the general formula (8), in the diamines of m = 1, 3,3′-dichlorobenzidine, 3,3′-dimethylbenzidine,
3,3'-dimethoxybenzidine, 3,3'-diaminodiphenyl ether, 3,3'-diamino-5,5'-
Ditrifluoromethyldiphenyl ether, 3,4'-
Diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfide, 3,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfone, 3,
4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4 '
-Dimethoxybenzophenone, 3,3'-diamino-4
-Phenoxybenzophenone, 3,3'-diamino-
4,4'-diphenoxybenzophenone, 3,3'-diamino-4- (4-phenyl) phenoxybenzophenone, 3,3'-diamino-4,4'-di (4-phenylphenoxy) benzophenone, 3,4 '-Diaminobenzophenone, 3,3'-diaminodiphenylmethane,
3,4'-diaminodiphenylmethane, 2,2-bis (3-aminophenyl) propane, 2,2-bis (4-
Aminophenyl) propane, 2,2-bis (3-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, and the like, and the diamines of m = 2 in the general formula (8) are , 1,3-bis (3-aminophenyl) benzene, 1,3-bis (4-aminophenyl) benzene, 1,4-bis (3-aminophenyl) benzene,
1,3-bis (3-aminophenoxy) benzene, 1,
3-bis (4-aminophenoxy) benzene, 1,4-
Bis (3-aminophenoxy) benzene, 1,3-bis (3-aminobenzoyl) benzene, 1,3-bis (4
-Aminobenzoyl) benzene, 1,4-bis (3-aminobenzoyl) benzene, 1,3-bis (3-aminophenylsulfide) benzene, 1,3-bis (4-aminophenylsulfide) benzene, 1,4 -Bis (3
-Aminophenyl sulfide) benzene, 1,3-bis (3-aminophenyl sulfone) benzene, 1,3-bis (4-aminophenyl sulfone) benzene, 1,4-
Bis (3-aminophenylsulfone) benzene, 1,3
-Bis (3-aminobenzyl) benzene, 1,3-bis (4-aminobenzyl) benzene, 1,4-bis (3-
Aminobenzyl) benzene, 1,3-bis (3-amino-α, α-dimethylbenzyl) benzene, 1,3-bis (4-amino-α, α-dimethylbenzyl) benzene,
1,4-bis (3-amino-α, α-dimethylbenzyl) benzene, 1,3-bis (3-aminophenoxy)
-4-trifluoromethylbenzene, 1,3-bis (3
-Aminophenoxy) -5-trifluoromethylbenzene, 1,3-bis (4-aminophenoxy) -4-trifluoromethylbenzene, 1,3-bis (4-aminophenoxy) -5-trifluoromethylbenzene, 1,4
-Bis (3-aminophenoxy) -3-trifluoromethylbenzene, 1,3-bis (3-amino-5-trifluoromethylphenoxy) benzene, 1,3-bis (3
-Amino-4-trifluoromethylphenoxy) benzene, 1,3-bis (4-amino-2-trifluoromethylphenoxy) benzene, 1,3-bis (4-amino-
3-trifluoromethylphenoxy) benzene, 1,4
-Bis (3-amino-5-trifluoromethylphenoxy) benzene, 1,4-bis (3-amino-4-trifluoromethylphenoxy) benzene, 1,3-bis (3
-Amino-5-trifluoromethylphenoxy) -4-
Trifluoromethylbenzene, 1,3-bis (3-amino-5-trifluoromethylphenoxy) -5-trifluoromethylbenzene, 1,3-bis (3-amino-4)
-Trifluoromethylphenoxy) -4-trifluoromethylbenzene, 1,3-bis (3-amino-4-trifluoromethylphenoxy) -5-trifluoromethylbenzene, 1,3-[(3-amino)- α, α-bis (trifluoromethyl) benzyl] benzene, 1,3-
[(4-Amino) -α, α-bis (trifluoromethyl) benzyl] benzene, 1,4-[(3-amino)-
α, α-bis (trifluoromethyl) benzyl] benzene, 1,3-bis (3-amino-4-fluorobenzoyl) benzene, 1,3-bis (3-amino-4-phenoxybenzoyl) benzene, 1, 3-bis [3-amino-4- (4-phenylphenoxy) benzoyl] benzene, 2,6-bis (3-aminophenoxy) benzonitrile, 1,3-bis (4-aminophenoxy) -2-phenylbenzene Etc., and m in the general formula (8)
= 3, the diamines are 4,4'-bis (3-aminophenoxy) biphenyl, 3,3'-bis (4-aminophenoxy) biphenyl, 3,3'-bis (3-aminophenoxy) biphenyl, bis. [4- (3-Aminophenoxy) phenyl] ether, bis [3- (4-aminophenoxy) phenyl] ether, bis [3- (3-aminophenoxy) phenyl] ether, bis [4- (3-
Aminophenoxy) phenyl] ketone, bis [3- (4
-Aminophenoxy) phenyl] ketone, bis [3-
(3-Aminophenoxy) phenyl] ketone, bis [4
-(3-Aminophenoxy) phenyl] sulfide, bis [3- (4-aminophenoxy) phenyl] sulfide, bis [3- (3-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl ] Sulfone, bis [3- (4-aminophenoxy) phenyl] sulfone, bis [3- (3-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] methane, bis [3- ( 4-aminophenoxy) phenyl] methane, bis [3- (3-aminophenoxy) phenyl] methane, 2,2-bis [4-
(3-Aminophenoxy) phenyl] propane, 2,2
-Bis [3- (4-aminophenoxy) phenyl] propane, 2,2-bis [3- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl]- 1,1,1,3,3,3-hexafluoropropane, 2,2-bis [3- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2 , 2-Bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-
Hexafluoropropane and the like can be mentioned. These diamines can be used alone or as a mixture, if necessary.

As the tetracarboxylic acid dianhydride used in the production of the polyamic acid and the polyimide resin according to the present invention, there may be mentioned at least one compound represented by the general formula (9). Specifically, in the general formula (9), X is an aliphatic group having 2 to 10 carbon atoms, a cycloaliphatic group having 4 to 10 carbon atoms, or a monocycle represented by the following formula (10). Formula aromatic group,

[Chemical formula 26] A condensed polycyclic aromatic group represented by the following formula (11),

[Chemical 27] And a tetracarboxylic dianhydride, which is a tetravalent group selected from the group consisting of non-fused polycyclic aromatic groups in which the aromatic groups represented by the following formula (12) are directly or cross-linked with each other by a bridging member. Things are used.

[Chemical 28] (In the formula, A is a direct bond, -CO-, -O-, -S-,-.
_{SO 2 -, - CH 2 -} , - C (CH 3) 2 -, - C (C
F ₃ ) ₂ −, or the following formula (13) is shown)

[Chemical 29] (Here, B is a direct bond, -CO-, -O-, -S-,
_{-SO 2 -, - CH 2 -} , - C (CH 3) 2 -, - C
(Indicates CF ₃ ) ₂ −)

The tetracarboxylic acid dianhydride represented by the general formula (9) used in the present invention is not limited, but examples thereof include ethylene tetracarboxylic acid dianhydride and butane tetracarboxylic acid dianhydride. Anhydride, cyclobutanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, pyromellitic dianhydride, 3,
3 ', 4,4'-benzophenone tetracarboxylic dianhydride, 2,2', 3,3'-benzophenone tetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride , 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride, 2,2-bis (3,4-
Dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-di) Carboxyphenyl) sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxy) Phenyl) methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis (2,3) −
Dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 1,3-bis [(3,
4-dicarboxy) benzoyl] benzene dianhydride,
1,4-bis [(3,4-dicarboxy) benzoyl]
Benzene dianhydride, 2,2-bis {4- [4- (1,2
-Dicarboxy) phenoxy] phenyl} propane dianhydride, 2,2-bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} propane dianhydride, bis {4- [4- (1 , 2-Dicarboxy) phenoxy] phenyl} ketone dianhydride, bis {4- [3- (1,2-
Dicarboxy) phenoxy] phenyl} ketone dianhydride, 4,4'-bis [4- (1,2-dicarboxy) phenoxy] biphenyl dianhydride, 4,4'-bis [3-
(1,2-Dicarboxy) phenoxy] biphenyl dianhydride, bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} ketone dianhydride, bis {4- [3-
(1,2-Dicarboxy) phenoxy] phenyl} ketone dianhydride, bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} sulfone dianhydride, bis {4- [3- (1 , 2-Dicarboxy) phenoxy] phenyl} sulfone dianhydride, bis {4- [4- (1,2
-Dicarboxy) phenoxy] phenyl} sulfide dianhydride, bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} sulfide dianhydride, 2,2-bis {4- [4- (1 , 2-Dicarboxy) phenoxy]
Phenyl} -1,1,1,3,3,3-hexaflupropane dianhydride, 2,2-bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} -1,1, 1,
3,3,3-propane dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 1,2,5,6 −
Naphthalenetetracarboxylic dianhydride, 1,2,3,4
-Benzenetetracarboxylic dianhydride, 3,4,9,1
0-perylene tetracarboxylic dianhydride, 2, 3, 6,
7-anthracene tetracarboxylic dianhydride, 1,2,
7,8-phenanthrene tetracarboxylic acid dianhydride and the like can be mentioned. These may be used alone or in combination of two or more.

In the production of the polyamic acid and the polyimide resin according to the present invention, an end capping agent can be used if necessary. Typical endcapping agents are monoamines or dicarboxylic acid anhydrides.

Examples of monoamines include aniline, o-toluidine, m-toluidine, p-toluidine, 2,3-xylidine, 2,4-xylidine, and 2,5.
-Xylidine, 2,6-xylidine, 3,4-xylidine, 3,5-xylidine, o-chloroaniline, m-chloroaniline, p-chloroaniline, o-bromoaniline, m-bromoaniline, p-bromoaniline , O-nitroaniline, m-nitroaniline, p-nitroaniline, o-anisidine, m-anisidine, p-anisidine, o-phenetidine, m-phenetidine, p-phenetidine, o-aminophenol, m-aminophenol, p-aminophenol, o-aminobenzaldehyde, m-aminobenzaldehyde, p-aminobenzaldehyde, o-aminobenzonitrile, m-aminobenzonitrile, p-aminobenzonitrile, 2-aminobiphenyl, 3-aminobiphenyl, 4- Aminobiphenyl, 2-aminophen Phenyl ether, 3-aminophenyl phenyl ether, 4-aminophenyl phenyl ether, 2-aminobenzophenone, 3-aminobenzophenone, 4-aminobenzophenone, 2-aminophenylphenyl sulfide, 3-aminophenylphenyl sulfide, 4-aminophenyl Phenyl sulfide, 2-aminophenylphenyl sulfone, 3-aminophenylphenyl sulfone, 4-aminophenylphenyl sulfone, α-naphthylamine, β-naphthylamine, 1-amino-2-naphthol, 2-amino-1-naphthol, 4- Amino-1-naphthol, 5-amino-
1-naphthol, 5-amino-2-naphthol, 7-amino-2-naphthol, 8-amino-1-naphthol,
8-amino-2-naphthol, 1-aminoanthracene, 2-aminoanthracene, 9-aminoanthracene, methylamine, dimethylamine, ethylamine, diethylamine, propylamine, dipropylamine, isopropylamine, diisopropylamine, butylamine, dibutylamine , Isobutylamine, diisobutylamine, pentylamine, dipentylamine, benzylamine, cyclopropylamine, cyclobutylamine,
Examples include cyclopentylamine and cyclohexylamine.

Examples of the dicarboxylic acid anhydride include:
Phthalic anhydride, 2,3-benzophenone dicarboxylic acid anhydride, 3,4-benzophenone dicarboxylic acid anhydride,
2,3-dicarboxyphenyl ether anhydride, 3,4
-Dicarboxyphenyl phenyl ether anhydride, 2,
3-biphenyldicarboxylic acid anhydride, 3,4-biphenyldicarboxylic acid anhydride, 2,3-dicarboxyphenylphenyl sulfone anhydride, 3,4-dicarboxyphenylphenyl sulfone anhydride, 2,3-dicarboxyphenylphenyl Sulfide anhydride, 3,4-dicarboxyphenylphenyl sulfide anhydride, 1,2-naphthalenedicarboxylic acid anhydride, 2,3-naphthalenedicarboxylic acid anhydride, 1,8-naphthalenedicarboxylic acid anhydride,
1,2-anthracene dicarboxylic acid anhydride, 2,3-anthracene dicarboxylic acid anhydride, 1,9-anthracene dicarboxylic acid anhydride and the like can be mentioned. A part of the structure of these monoamine or dicarboxylic acid anhydride may be substituted with a group that is not reactive with the amine or dicarboxylic acid anhydride.

In producing the polyamic acid according to the present invention, it is a preferable method to carry out the reaction in an organic solvent. The solvent used in the reaction is not limited, but examples thereof include the following (a) to (e).

(A) Phenol-based solvents such as phenol, o-chlorophenol, m-chlorophenol,
p-chlorophenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-
Xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol.

(B) N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-which are aprotic amide solvents. 2-Imidazolidinone, N-methylcaprolactam, hexamethylphosphorotriamide.

(C) 1,2- which is an ether solvent
Dimethoxyethane, bis (2-methoxyethyl) ether, 1,2-bis (2-methoxyethoxy) ethane, tetrahydrofuran, bis [2- (2-methoxyethoxy) ethyl] ether, 1,4-dioxane.

(D) Amine-based solvent, pyridine,
Quinoline, isoquinoline, α-picoline, β-picoline, γ-picoline, isophorone, piperidine, 2,4-
Lutidine, 2,6-lutidine, trimethylamine, triethylamine, tripropylamine, tributylamine.

(E) Other solvents, such as dimethyl sulfoxide, dimethyl sulfone, diphenyl ether,
Sulfolane, diphenyl sulfone, tetramethyl urea,
Anisole etc.

In addition, these solvents may be used alone or in combination of two or more kinds. Among these solvents, N, N-dimethylformamide and N, N-dimethylacetamide are particularly preferable.

In the production of the polyamic acid according to the present invention, a known catalyst can be used in combination. For example, as the base catalyst, various amine solvents described in (d) above, imidazole, N, N-dimethylaniline, N, N
-Organic bases such as diethylaniline, and inorganic bases represented by potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium hydrogen carbonate, and sodium hydrogen carbonate. Examples of acid catalysts include crotonic acid, acrylic acid, trans-3-hexenoic acid, cinnamic acid, benzoic acid, methylbenzoic acid, oxybenzoic acid, terephthalic acid, benzenesulfonic acid, paratoluenesulfonic acid and naphthalenesulfonic acid. To be

In the production of the polyamic acid according to the present invention, the concentration of the polyamic acid in the polyamic acid solution (hereinafter referred to as the polymerization concentration) is not limited at all. A preferable polymerization concentration is 5 to 40% by weight, and more preferably,
It is 10 to 30% by weight.

In the production of the polyamic acid solution according to the present invention, the reaction temperature, reaction time and reaction pressure are not particularly limited and known conditions can be applied. That is, the reaction temperature is preferably in the range of -10 to 100 ° C, more preferably in the vicinity of the ice cooling temperature to around 60 ° C, and most preferably in practical use and in the range of 50 to 60 ° C.
℃. The reaction time varies depending on the type of monomer used, the type of solvent, and the reaction temperature, but is 1 to 4
8 hours is preferred. It is more preferably about 2 to 3 hours to about a dozen hours, and most preferably 4 to 10 hours in terms of implementation. Further, the reaction pressure may be normal pressure.

In the present invention, the logarithmic viscosity of the polyamic acid and the polyimide resin is not particularly limited, but the logarithmic viscosity is preferably 0.1 to 2.0,
0.2 to 1.9 is more preferable, and 0.3 to 1.8 is still more preferable.

A conventionally known method can be used for producing the carbon film of the present invention. That is, first, a polyamic acid, which is a precursor of a polyimide resin having the above structure, is dissolved in an appropriate organic solvent such as N, N-dimethylacetamide, coated on a porous substrate, and then the coated solution is heated. Then, it is dried to form a polyimide layer obtained from polyamic acid on the surface of the porous substrate. The coating may be repeated a plurality of times as necessary so that a predetermined film thickness can be obtained. The conversion from polyamic acid to polyimide is usually 5
It is carried out by heating at 0 to 400 ° C. The preferable imidization temperature is 100 to 300 ° C.

As a material of the porous base material which becomes the support of the carbon film, alumina, silica, cordierite and the like are preferable. The porosity of the porous substrate is preferably about 25 to 55% from the viewpoint of strength and permeability of the substrate. The average pore size of the porous substrate is
It is preferably about 0.005 to 5 μm. The thickness of the porous substrate may be selected within a range that satisfies the strength required as a support and does not impair the permeability of the separated component, and the shape is also appropriately selected according to the intended use of the carbon membrane. be able to.

After the application to the porous substrate is completed, the applied solution is heated and dried, and the solvent is evaporated by heat treatment to convert the polyamic acid into polyimide to form a polyimide layer which is a precursor of the carbon film. Form. This is 400-750 under oxygen inert atmosphere, such as nitrogen atmosphere.
Carbonization is carried out by thermal decomposition in the temperature range of about 0 ° C. to obtain the carbon film of the present invention.

The film thickness of the finally obtained carbon film is 1 to
The thickness is preferably 50 μm, and more preferably 1 to 10 μm. If the film thickness of the carbon film is less than 1 μm, it is difficult to form the carbon film and it is difficult to obtain sufficient gas selectivity, and if it exceeds 50 μm, the film becomes thick and the gas permeation rate becomes low. .

In producing the carbon film of the present invention, before forming the polyimide layer (that is, before applying the polyamic acid which is a precursor of the polyimide resin),
It is preferable that the surface of the porous base material to be the formation surface (application surface) is subjected to a base treatment in which an epoxy resin is applied. By performing such a base treatment, the permeation rate can be improved without impairing the gas separation performance.

It is considered that this is because the base treatment reduces the penetration of the polyimide resin, which is the carbon source of the carbon film, into the porous base material, and the carbon film is formed on the surface of the base material. That is, when the above-described base treatment is not performed, a part of the polyimide resin enters the inside of the porous base material and is carbonized, so that the gas that has permeated the carbon film on the surface of the porous base material is more effective. It must pass through the carbon film portion that has entered the inside of the base material where the film area decreases, which increases resistance and decreases the permeation rate. On the other hand, when the above-mentioned base treatment is performed, the gas that has permeated the carbon film on the surface of the porous base material diffuses into the pores inside the base material where the effective film area decreases, so Is smaller and the transmission speed is improved.

When the carbon film of the present invention is left at room temperature, water molecules may be adsorbed by oxygen-containing functional groups, which are present on the surface of the carbon film in a very small amount, and the permeation performance may be deteriorated. In order to prevent such deterioration of the permeation performance, the precursor may be thermally decomposed and carbonized in an oxygen-inert atmosphere, and then the surface of the obtained carbon film may be subjected to silylation treatment.
By thus subjecting the surface of the carbon film to the silylation treatment, it is possible to impart hydrophobicity to the carbon film and prevent the deterioration of the permeation performance due to the adsorption of water molecules as described above. However, by performing the silylation treatment,
Since the pore size of the carbon film becomes smaller and the initial permeation rate becomes lower than that in the case where silylation is not performed, caution is required in the silylation treatment of the carbon film that requires a high permeation rate.

[0039]

EXAMPLES Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

(Example 1) Polyamic acid which is a precursor of the polyimide represented by the structural formula (4) is polymerized in N, N-dimethylacetamide, and the polyamic acid content is 30 wt%. Solution I was obtained. A 1 cm square porous alumina substrate (Nippon Gaishi Co., Ltd., average pore size 0.1 μm) was dried at 180 ° C. and dehydrated, and then the polyamic acid solution I was applied onto the porous alumina substrate. After being held in a desiccator for 2 hours, polyamic acid solution I was further applied. Then, in a dryer in an air atmosphere at 90 ° C for 2 hours, 150 ° C for 2 hours, and 180 ° C for 2 hours.
A heat treatment was performed for a day to obtain a carbon film precursor. The obtained carbon film precursor was heated in a nitrogen furnace in a nitrogen furnace to 400
It heat-processed at 6 degreeC for 6 hours, and obtained the carbon film. The rate of temperature rise during this heat treatment was 1 ° C./min.

(Example 2) A carbon film precursor was obtained by the same procedure as in Example 1, and the carbon film precursor was subjected to 50% in a nitrogen furnace in a nitrogen atmosphere.
It heat-processed at 0 degreeC for 6 hours, and obtained the carbon film. The rate of temperature rise during this heat treatment was 1 ° C./min.

Example 3 A carbon film precursor was obtained in the same procedure as in Example 1 described above, and the carbon film precursor was subjected to 50% in a ring furnace in a nitrogen atmosphere.
It heat-processed at 0 degreeC for 2 hours, and obtained the carbon film. The rate of temperature rise during this heat treatment was 5 ° C./min.

(Example 4) Polyamic acid as a precursor of the polyimide represented by the structural formula (5) was polymerized in N, N-dimethylacetamide, and the polyamic acid content was 30 wt%. Solution II was obtained. A 1 cm square porous alumina substrate (Nippon Gaishi Co., Ltd., average pore diameter 0.1 μm) was dried at 180 ° C. and dehydrated, and then the polyamic acid solution II was applied onto the porous alumina substrate. After being kept in a desiccator for 2 hours, a polyamic acid solution II was further applied. Then, in a dryer in an air atmosphere at 90 ° C for 2 hours, 150 ° C for 2 hours, and 180 ° C for 2 hours.
A heat treatment was performed for a day to obtain a carbon film precursor. The precursor of the obtained carbon film was heated to 500 in a ring furnace in a nitrogen atmosphere.
It heat-processed at 6 degreeC for 6 hours, and obtained the carbon film. The rate of temperature rise during this heat treatment was 1 ° C./min.

Example 5 The polyamic acid solution II used in Example 4 was further diluted with N, N-dimethylacetamide to obtain a polyamic acid solution III having a polyamic acid content of 15 wt%. Using this polyamic acid solution III, a carbon film precursor was obtained in the same procedure as in Example 4,
Heat treatment was performed at 500 ° C. for 1 hour in a ring furnace in a nitrogen atmosphere to obtain a carbon film. The rate of temperature rise during this heat treatment is 5 ° C /
It was set to min.

COMPARATIVE EXAMPLE 1 Polyamide acid, which is a precursor of the polyimide represented by the structural formula (7), is polymerized in N, N-dimethylacetamide, and polyamide # acid content is 25 wt%. An acid solution IV was obtained. 1 cm
A square porous alumina substrate (manufactured by NGK Insulators Co., Ltd., average pore diameter 0.1 μm) is dried at 180 ° C. and dehydrated, and then the polyamic acid solution IV is applied onto the porous alumina substrate, After being kept in a desiccator for 2 hours, a polyamic acid solution IV was further applied. Then, in a dryer in an air atmosphere at 90 ° C for 2 hours, 150 ° C for 2 hours, and 180 ° C for 2 hours.
A heat treatment was performed for a day to obtain a carbon film precursor. The precursor of the obtained carbon film was heated to 500 in a ring furnace in a nitrogen atmosphere.
It heat-processed at 6 degreeC for 6 hours, and obtained the carbon film. The rate of temperature rise during this heat treatment was 1 ° C./min.

(Comparative Example 2) A carbon film precursor was obtained by the same procedure as in Comparative Example 1, and was subjected to 60% in a ring furnace in a nitrogen atmosphere.
Heat treatment was performed at 0 ° C. for 6 hours to obtain a carbon film. The rate of temperature rise during this heat treatment was 1 ° C./min.

(Comparative Example 3) A carbon film precursor was obtained in the same procedure as in Comparative Example 1, and the carbon film precursor was subjected to 70% in a nitrogen furnace in a ring furnace.
Heat treatment was performed at 0 ° C. for 6 hours to obtain a carbon film. The rate of temperature rise during this heat treatment was 1 ° C./min.

(Comparative Example 4) A carbon film precursor was obtained by the same procedure as in Comparative Example 1, and the carbon film precursor was heated in a nitrogen furnace in a nitrogen atmosphere at 80 ° C.
Heat treatment was performed at 0 ° C. for 6 hours. The rate of temperature rise during this heat treatment was 1 ° C./min. At the heat treatment temperature of 800 ° C., the carbonized film was easily peeled off, and a film integrated with the porous substrate could not be obtained.

[Evaluation of Gas Separation Performance] Using the evaluation apparatus shown in FIG. 1, the gas separation performance of the carbon membranes obtained in Examples 1 to 5 and Comparative Examples 1 to 3 was evaluated. The gas permeation performance of the carbon membrane was evaluated by the size of the permeation rate R represented by the following mathematical formula (I). The permeation rate ratio R (O ₂ ) / R (N ₂ ) was used as an index of the separation performance of the carbon membrane. A test gas (single gas) was supplied at a constant pressure (4 kg / cm ² (gauge pressure)) to one surface of the carbon film (evaluation sample) mounted on the cell of the measuring device, and the other surface of the film was at atmospheric pressure. age,
After sweeping with argon gas, the gas permeation flow rate was determined by TCD gas chromatography.

[0050]

## EQU1 ## R = P / L = Q / (p ₁ −p ₂ ) At (I) R: Permeation rate [mol / (m ² · s · Pa)] P: Permeation coefficient [mol · m / (M ² · s · Pa)] L: film thickness [m] A: film area [m ² ] Q: gas permeation amount [mol] p ₁ : high pressure side gas pressure [Pa] p ₂ : low pressure side gas pressure [ Pa] t: time [s]

In addition, air dried using silica gel was supplied to the evaluation sample, and the separation performance with air was evaluated. For the evaluation of the gas permeation performance, the permeation rate R was used as in the case of the single gas. Further, a separation coefficient α represented by the following mathematical formula (II) was used as an index for evaluating the separation performance. In the formula, Perm (O ₂ ) and Perm (N ₂ ) are oxygen permeated through the membrane,
The molar concentrations of nitrogen, Feed (O ₂ ), and Feed (N ₂ ) are the molar concentrations of oxygen and nitrogen on the supply side. Since dry air is used, Feed (O ₂ ) / Feed (N ₂ ) is 0.25. Table 1 shows the production conditions of the carbon membrane, the gas permeation performance using a single gas, and the evaluation results of the air separation performance using dry air.

[0052]

[Formula 2] α = (Perm (O ₂ ) / Perm (N ₂ )) / (Feed (O ₂ ) / Feed (N ₂ )) (II)

[0053]

[Table 1]

As shown in Table 1, the carbon membranes of Examples 1 to 5 produced by using the polyimide of the structural formula (4) or (5) have the single gas permeation rate ratio R (O ₂ ) / R ( N ₂ )
Are 2.5 or more, and higher separation performance can be expected than the carbon membranes of Comparative Examples 1 to 3 produced using the polyimide of the structural formula (7). Further, regarding the evaluation using dry air, the carbon membranes of Comparative Examples 1 to 3 have a separation coefficient α of about 1 and hardly separate oxygen, whereas the carbon membranes of Examples 1 to 5 have a separation coefficient α of 1. The oxygen separation performance was 5 or more. It should be noted that oxygen can be enriched to approximately 27% with a separation factor of 1.5.

Example 6 A polyamic acid having a polyamic acid content of 30 wt% was obtained by polymerizing polyamic acid, which is a precursor of the polyimide represented by the structural formula (4), in N, N-dimethylacetamide. Solution I was obtained. A 1 cm square porous alumina substrate (manufactured by Nippon Gaishi Co., Ltd., average pore diameter 0.1 μm) was dried at 180 ° C. and dehydrated, and then an epoxy resin was applied to this porous alumina substrate to form a substrate. Substrate treatment was performed. The polyamic acid solution I was applied onto the porous alumina substrate thus undertreated, and the polyamic acid solution I was further applied after holding for 2 hours in a desiccator. Then, in an air atmosphere in a dryer, 90 ℃
2 hours, 150 ° C. for 2 hours, and 180 ° C. for 2 days to obtain a carbon film precursor. The obtained carbon film precursor was heat-treated at 400 ° C. for 6 hours in a ring furnace in a nitrogen atmosphere to obtain a carbon film. The rate of temperature rise during this heat treatment was 1 ° C./min.

(Example 7) Polyamic acid which is a precursor of the polyimide represented by the structural formula (5) is polymerized in N, N-dimethylacetamide, and the polyamic acid has a polyamic acid content of 30 wt%. Solution II was obtained. A 1 cm square porous alumina substrate (manufactured by Nippon Gaishi Co., Ltd., average pore diameter 0.1 μm) was dried at 180 ° C. and dehydrated, and then an epoxy resin was applied to this porous alumina substrate to form a substrate. Substrate treatment was performed. The polyamic acid solution II was applied onto the porous alumina substrate thus undertreated, and the polyamic acid solution II was further applied after holding in a desiccator for 2 hours. Then, in an air atmosphere in a dryer, 90 ℃
2 hours, 150 ° C. for 2 hours, and 180 ° C. for 2 days to obtain a carbon film precursor. The obtained carbon film precursor was heat-treated at 500 ° C. for 6 hours in a ring furnace in a nitrogen atmosphere to obtain a carbon film. The rate of temperature rise during this heat treatment was 1 ° C./min.

[Evaluation of Gas Separation Performance] Examples 1 to 5
And the gas separation performance of the carbon membranes obtained in Examples 6 and 7 was evaluated in the same manner as in Comparative Examples 1 to 3. The results are shown in Table 2. In addition, the second embodiment in which the base treatment is not applied
The evaluation results of the carbon films of 4 and 4 are also shown in the same table.

[0058]

[Table 2]

From the comparison of the evaluation results of the carbon films of Examples 6 and 7 which have been subjected to the base treatment and the carbon films of Examples 2 and 4 which have not been subjected to the base treatment, by applying the base treatment,
It can be seen that the oxygen permeation rate can be improved while maintaining the oxygen separation performance. This is because when no base treatment is applied, the polyamic acid, which is the precursor of the polyimide serving as the carbon source of the carbon film, penetrates into the base material and is carbonized after imidization. Since the effective membrane area in the inside becomes smaller, the permeation rate becomes lower, while
It is considered that the base treatment is less likely to cause the polyamic acid to enter the inside of the base material and a carbon film is formed on the surface of the base material.

Example 8 The carbon film obtained in Example 6 was stored in the atmosphere for 1 month, and then the permeation rate of oxygen alone was measured. Further, after leaving it in saturated steam at 80 ° C. for 24 hours, the permeation rate of oxygen alone was measured, and it was confirmed that the gas permeation ability was lowered. After drying this carbon film at 180 ° C., using trimethylchlorosilane as a silylating agent,
Silylation was carried out at 150 ° C. for 2 hours. The permeation rate of oxygen alone in the carbon film after silylation and the permeation rate of oxygen alone after standing in saturated steam at 80 ° C. for 24 hours were measured to evaluate the hydrophilicity / hydrophobicity. The results are shown in Table 3.

[0061]

[Table 3]

From the evaluation results shown in Table 3, it was confirmed that by subjecting the surface of the carbon film to the silylation treatment, the oxygen permeation rate of the carbon film hardly changed even after the steam treatment from before the steam treatment. it can. However,
The initial oxygen permeation rate decreased to about 1/200 as compared with the case where no silylation treatment was applied. It is considered that this is because the pores of the carbon film became smaller and the oxygen permeation performance decreased due to the silylation treatment.

(Example 9) A carbon film precursor was obtained in the same procedure as in Example 1, and the temperature was set to 600 ° C in an annular furnace in a nitrogen atmosphere.
A heat treatment was performed for 6 hours to obtain a carbon film. The rate of temperature rise during this heat treatment was 1 ° C./min. The obtained carbon membrane was evaluated for gas separation performance in the same manner as in Examples 1 to 5 and Comparative Examples 1 to 3, but showed no oxygen selectivity. This carbon film was silylated at 150 ° C. for 2 hours using trimethylchlorosilane as a silylating agent. When the gas separation performance of the carbon film after silylation was evaluated again by the same method, it showed oxygen selectivity. Also,
After being left in 80 ° C. saturated steam for 24 hours, the permeation rate of oxygen alone was measured to evaluate the hydrophilicity / hydrophobicity. The results are shown in Table 4.

[0064]

[Table 4]

From the evaluation results shown in Table 4, it can be seen that a film exhibiting oxygen selectivity can be modified by subjecting a film showing no oxygen selectivity to silylation treatment. Further, since there is almost no change in the oxygen permeation rate before and after the steam treatment, it is understood that the silylation treatment imparts hydrophobicity to the carbon film.

[0066]

As described above, according to the present invention, it is possible to obtain a carbon film having a sufficiently large separation coefficient and an improved permeation rate as compared with the conventional one. The carbon film of the present invention is
For example, it can be effectively used industrially as an oxygen-enriched membrane or a hydrogen separation membrane.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an apparatus used for evaluation of gas separation performance in Examples.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // C04B 35/52 C04B 35/52 A (72) Inventor Takuya Hiramatsu 2 Suda Town, Mizuho-ku, Nagoya City, Aichi Prefecture No. 56 Insulator Nihonmoto Co., Ltd. (72) Inventor Norikazu Nishiyama 1-8-43-307 Shibahara-cho, Toyonaka-shi, Osaka (72) Inventor Wataru Momose 2-3-6-205 Wataruikehigashi-cho, Toyonaka-shi, Osaka ( 72) Inventor Yasuyuki Egashira 5-14-30-401 Minoh, Minoh City, Osaka Prefecture (72) Inventor Souichi Ueyama 6-28-307 (72) Inventor Masaji Tamai, Mayor Sodegaura, Chiba Prefecture 580 Ura 32 F term in Mitsui Chemicals Co., Ltd. (reference) 4D006 GA41 MA03 MA22 MA24 MC05X NA50 PA04 4G073 BA62 BD18 CZ53 UA06 4G132 AA16 BA22 CA12 CA14 GA01 GA25 GA28 GA30 4G146 AA01 AB07 AD12 AD15 BA15 BA17 BA20 BB23 BC0 3 BC23 BC32B BC33B BC37B CB22 4J043 PA01 PA02 PA04 PA08 QB15 QB26 RA05 RA35 SA06 SB01 SB02 TA22 TB01 TB02 UA012 UA122 UA131 UA132 UA141 UA142 UA151 UA262 UA762 UB01BAZB13B06B13B13A06B13B13A06B13B13A13B27B13A13

Claims (9)

[Claims] 1. The repeating unit is represented by the following general formula (1).
Polyimide resin (where X is a carbon number of 2 to 27)
Aliphatic groups, cycloaliphatic groups, monocyclic aromatic groups, condensed polycycles
Formula Aromatic group, and aromatic groups are mutually or directly
Selected from the group consisting of non-fused polycyclic aromatic groups linked to
Is a tetravalent group, and n is an integer of 5 to 10000.
Y is represented by the following general formula (2), and the general formula (2)
Of the phenylene groups forming the main chain skeleton,
At least one is an m-phenylene group, Z is directly connected,
O-, -CO-, -S-, -SO₂-, -CH₂-, -C
(CH ₃)₂-Or-C (CF₃)₂Indicates −, and m is 1 to 3.
, An integer of R,_1-4And R '_1-4Is -H,-
F, -Cl, -Br, -I, -CN, -CH₃ , -CF
₃, -OCH₃, Phenyl group, 4-phenylphenyl group,
A phenoxy group or a 4-phenylphenoxy group, R
_1-4And R '_1-4Are all the same or different
Well, and only a part of them may be the same)
A polyamic acid represented by the following general formula (3)
Where X and Y represent the same groups as above)
Coated on the surface, heated and dried to form a carbon film precursor,
By thermally decomposing the precursor in an oxygen-inert atmosphere,
A carbon film characterized by being obtained. [Chemical 1] [Chemical 2] [Chemical 3] 2. The polyimide resin has the following structural formula (4):
The carbon film according to claim 1, which is represented by [Chemical 4] 3. The polyimide resin has the following structural formula (5):
The carbon film according to claim 1, which is represented by [Chemical 5] 4. The carbon film according to claim 1, wherein the precursor of the carbon film is thermally decomposed in an oxygen-inert atmosphere, and then the film surface is subjected to silylation treatment. 5. The carbon film according to claim 1, wherein the porous substrate has an average pore diameter of 0.005 to 5 μm and a porosity of 25 to 55%. 6. The repeating unit is represented by the following general formula (1).
Polyimide resin (where X is a carbon number of 2 to 27)
Aliphatic groups, cycloaliphatic groups, monocyclic aromatic groups, condensed polycycles
Formula Aromatic group, and aromatic groups are mutually or directly
Selected from the group consisting of non-fused polycyclic aromatic groups linked to
Is a tetravalent group, and n is an integer of 5 to 10000.
Y is represented by the following general formula (2), and the general formula (2)
Of the phenylene groups forming the main chain skeleton,
At least one is an m-phenylene group, Z is directly connected,
O-, -CO-, -S-, -SO₂-, -CH₂-, -C
(CH ₃)₂-Or-C (CF₃)₂Indicates −, and m is 1 to 3.
, An integer of R,_1-4And R '_1-4Is -H,-
F, -Cl, -Br, -I, -CN, -CH₃ , -CF
₃, -OCH₃, Phenyl group, 4-phenylphenyl group,
A phenoxy group or a 4-phenylphenoxy group, R
_1-4And R '_1-4Are all the same or different
Well, and only a part of them may be the same)
A polyamic acid represented by the following general formula (3)
(Wherein X and Y represent the same groups as described above) on the surface of the porous substrate.
To form a carbon film precursor.
Characterized by thermally decomposing the precursor in an oxygen-inert atmosphere
And a method for producing a carbon film. [Chemical 6] [Chemical 7] [Chemical 8] 7. The production according to claim 6, wherein before applying the polyamic acid which is the precursor of the polyimide resin, a surface treatment is applied to apply an epoxy resin to the surface of the porous base material which is the application surface. Method. 8. The production method according to claim 6, wherein after the precursor of the carbon film is thermally decomposed in an oxygen-inert atmosphere, the surface of the obtained carbon film is subjected to silylation treatment. 9. The production method according to claim 6, wherein the porous substrate has an average pore diameter of 0.005 to 5 μm and a porosity of 25 to 55%.