JP2003055457A - Sulfonic acid-containing ion conductive polybenzimidazole - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polymeric material which enhances the proton conductivity of a polybenzimidazole based polymer having a sulfonic acid group on the aromatic ring and excellent properties such as heat resistance and mechanical properties and, simultaneously, has sufficient water resistance when used as a polymeric electrolyte membrane. SOLUTION: The sulfonic acid group-containing polybenzimidazole compound has a polymer composed of a repeating unit to be represented by formula (1) [wherein X is selected from -O-, -SO2 -, -C(CH3 )2 -, -C(CF3 )2 -, -OPhO-, and a direct bond; Ar is selected from aromatic groups containing 0-2 sulfonic groups and contains an average of 0.5 per Ar of the sulfonic acid group; and R is selected from hydrogen, a 2-12C aliphatic group, an aromatic group, an aliphatic/ aromatic substituent, a 2-12C aliphatic sulfonic acid group, an aromatic sulfonic acid group, and an aliphatic/aromatic sulfonic acid substituent] as the major component, has an inherent viscosity, measured in sulfuric acid, of >=0.1 and, simultaneously, is substantially insoluble in water.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a sulfonic acid group-containing polybenzimidazole resin useful as a polymer electrolyte membrane.

[0002]

2. Description of the Related Art As an example of an electrochemical device using a solid polymer electrolyte as an ion conductor instead of a liquid electrolyte, a water electrolysis cell or a fuel cell can be used. The polymer membranes used for these must be sufficiently stable chemically, thermally, electrochemically and mechanically as a cation exchange membrane together with proton conductivity. Therefore, as a material that can be used for a long period of time, a perfluorocarbon sulfonic acid membrane typified by "Nafion (registered trademark)" manufactured by DuPont, USA has been mainly used. However, if you try to operate at a temperature above 100 ° C,
The water content of the membrane drops sharply and the membrane softens significantly. Therefore, in a fuel cell that uses methanol as a fuel, which is expected in the future, the performance of the fuel cell deteriorates due to the permeation of methanol in the membrane, and it is not possible to exhibit sufficient performance. In addition, hydrogen, which is currently being studied, is used as fuel.
It has been pointed out that even in a fuel cell operating near 0 ° C., the cost of the membrane is too high as an obstacle to establishing the fuel cell technology.

In order to overcome such drawbacks, various studies have been made on polymer electrolyte membranes in which a sulfonic acid group is introduced into an aromatic ring-containing polymer. For example, sulfonated polyaryl ether sulfone (Journal of Membrane
Science, 83 , 211 (1993)), sulfonated polyetheretherketone (JP-A-6-93114), sulfonated polystyrene and the like. However, a sulfonic acid group introduced on an aromatic ring from a polymer as a raw material is apt to undergo a desulfonic acid reaction due to an acid or heat, and cannot be said to have sufficient durability for use as an electrolyte membrane for a fuel cell.

As a polymer having high heat resistance and high durability, aromatic polyazole-based polymers such as polybenzimidazole are known, and it is conceivable to introduce a sulfonic acid group into these polymers and utilize them for the above purpose. . As such a polymer structure, polybenzimidazole containing sulfonic acid is described in Uno et al., J. Polym. Sc.
i., Polym. Chem., 15 , 1309 (1977) 3,3'-
What is synthesized from diaminobenzidine and 3,5-dicarboxybenzenesulfonic acid or 4,6-dicarboxy-1,3-benzenedisulfonic acid is USP 5312.
In 895, 1,2,4,5-benzenetetramine and 2,
It has been reported to synthesize 5-dicarboxybenzenesulfonic acid as a main component. However, in these reports, the electrochemical characteristics of the sulfonic acid group such as those for use in electrolyte membranes were not considered. Therefore, the heat resistance, the solvent resistance, the mechanical properties and the ionic conduction properties are made compatible, and the molecular design considering the processability has not been made, and at least any one of them should be used for the polymer electrolyte membrane. It was inferior to that characteristic.

On the other hand, applying polybenzimidazole to sulfuric acid or phosphoric acid, for example, is to apply polybenzimidazole to sulfuric acid or phosphoric acid by paying attention to the heat resistance, solvent resistance, mechanical properties and the like of polybenzimidazole. USP that a polymer electrolyte membrane with excellent proton conductivity at high temperature can be obtained at
5,525,436. Also,
A polymer electrolyte prepared by introducing a sulfonic acid group into polybenzimidazole is a polymer electrolyte prepared by introducing an N-alkylsulfonic acid into polybenzimidazole.
73908 and USP 4814399. In addition, Abstracts of Polymer Symposium, 49, p. 3217
(2000), N-alkylsulfonic acid-containing polybenzimidazole was used for the purpose of improving the mechanical strength of N.
-A polymer is shown which has a structure which also contains an alkyl chain. As described above, in an attempt to obtain a polymer electrolyte membrane by introducing a sulfonic acid group into polybenzimidazole, a method using N-alkylsulfonic acid has been studied so far, and an aromatic compound of polybenzimidazole has been studied. No studies have been reported on those in which a sulfonic acid group is directly introduced onto the group ring. Regarding a polymer in which a sulfonic acid group is introduced on the aromatic ring of polybenzimidazole having an N-alkylsulfonic acid structure, USP 5,312,
However, since the polymer itself is water-soluble, it cannot be originally used as a proton-conducting polymer electrolyte membrane used in the presence of water. Has not been evaluated.

As described above, the sulfonic acid introduced on the aromatic ring of polybenzimidazole is J. Polym. Sci., Po.
lym. Chem., 15 , 1309 (1977), even though it is expected to have much higher thermal stability than other sulfonated polyarylene ethers, it has high thermal stability. It was not examined in detail as a molecular electrolyte membrane. This is mainly because the imidazole ring, which has the characteristics of a sulfonic acid group and a basic group on the aromatic ring, forms a salt in the molecule or between the molecules, so that the conductivity of the proton is maintained even in the electric field. Is considered to be limited.

[0007]

The object of the present invention is to increase the proton conductivity of a polybenzimidazole-based polymer having a sulfonic acid group on an aromatic ring, which has excellent properties such as heat resistance and mechanical properties, and at the same time, to improve the proton conductivity. The purpose is to obtain a polymer material having sufficient water resistance when used as a molecular electrolyte membrane.

[0008]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the inventors of the present invention have conducted carbon-based substitution of hydrogen on the imidazole ring of a polybenzimidazole-based polymer containing a specific sulfonic acid group. By converting it into a group, it is possible to improve the proton conduction property while maintaining water resistance, and it has become possible to obtain a polymer material useful as a polymer electrolyte membrane used in fuel cells and the like.

That is, the present invention is achieved by the following (1) to (5). (1) A polymer having a repeating unit represented by the following general formula (1) as a main component, having a logarithmic viscosity of 0.1 or more as measured in sulfuric acid and being substantially insoluble in water. A polybenzimidazole compound containing a sulfonic acid group.

[Chemical 2] (In the formula, X is —O—, —SO ₂ —, —C (CH ₃ ) ₂ —,
_{-C (CF 3) 2 -,} - OPhO-, selected from a direct bond. Ar is selected from aromatic groups containing 0 to 2 sulfonic acid groups, and the average value of sulfonic acid groups is 0.5 or more per Ar. R is hydrogen, aliphatic having 2 to 12 carbon atoms,
It is selected from aromatic, aliphatic / aromatic substituents and aliphatic sulfonic acids having 2 to 12 carbon atoms, aromatic sulfonic acids, and aliphatic / aromatic sulfonic acid substituents. )

(2) In the general formula (1) in the above (1), R is selected from hydrogen, an aliphatic group having 2 to 12 carbon atoms, an aromatic group, and an aliphatic / aromatic substituent group. Sulfonic acid group-containing polybenzimidazole compound.

(3) In the general formula (1) in the above (1), R is selected from hydrogen, an aliphatic sulfonic acid having 2 to 12 carbon atoms, an aromatic sulfonic acid, and an aliphatic / aromatic sulfonic acid substituent. A benzimidazole compound containing a sulfonic acid group.

(4) A molded product comprising the sulfonic acid group-containing polybenzimidazole compound as described in (1) to (3) above as a main component.

(5) A membrane comprising the sulfonic acid group-containing polybenzimidazole compound according to the above (1) to (4) as a main component.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The present invention comprises, as a main component, a polymer comprising a repeating unit represented by the following general formula (1), and a sulfonic acid group-containing polybenzimidazole compound, and a molded article and a film containing the same as a main component. Thus, a material which is a polymer solid electrolyte having excellent heat resistance and mechanical properties and also having sufficiently high proton conductivity is provided.
Since this resin composition is used as a polymer electrolyte material, its logarithmic viscosity measured in sulfuric acid must be 0.1 or more and it must be substantially insoluble in water. When the logarithmic viscosity is lower than this, problems such as difficulty in handling occur.

[0015]

[Chemical 3] (In the formula, X is —O—, —SO ₂ —, —C (CH ₃ ) ₂ —,
_{-C (CF 3) 2 -,} - OPhO-, selected from a direct bond. Ar is selected from aromatic groups containing 0 to 2 sulfonic acid groups, and the average value of sulfonic acid groups is 0.5 or more per Ar. R is hydrogen, aliphatic having 2 to 12 carbon atoms,
It is selected from aromatic, aliphatic / aromatic substituents and aliphatic sulfonic acids having 2 to 12 carbon atoms, aromatic sulfonic acids, and aliphatic / aromatic sulfonic acid substituents. )

The sulfonic acid group-containing polybenzimidazole compound represented by the above general formula (1) is described in JP-A-9-73908 and USP4814399, in contrast to polybenzimidazole having a sulfonic acid group on the aromatic ring. The hydrogen on the imidazole ring nitrogen to N
It can be obtained by substituting with a, Li or the like and then reacting with alkyl bromide or sultones. As R in the above formula (1), specifically, a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group,
n-hexyl group, n-heptyl group, n-octyl group, n
-Nonyl group, n-decyl group, n-undecyl group, linear alkyl group such as n-dodecyl group, isopropyl group, isobutyl group, 2-methylpropyl group, sec-butyl group, t
ert-butyl group, isopentyl group, isohexyl group,
Examples include branched alkyl groups including 2-methylpentyl group, aromatic groups such as phenyl group, naphthyl group, toluyl group, and aliphatic / aromatic substituents such as benzyl group, but are not limited thereto. is not. Further, some hydrogen atoms on these substituents may be replaced with other substituents such as a hydroxyl group and a halogen group, or an element. Also,
Specific examples of R include a methylsulfonic acid group and 2-
Ethylsulfonic acid group, 3-propylsulfonic acid group, 4-
Butyl sulfonic acid group, 5-pentyl sulfonic acid group, 6
-Hexyl sulfonic acid group, 7-heptyl sulfonic acid group,
8-octyl sulfonic acid group, 9-nonyl sulfonic acid group,
Alkylsulfonic acid groups such as 10-decylsulfonic acid group, 11-undecylsulfonic acid group and 12-dodecylsulfonic acid group, 4-phenylsulfonic acid group, 3-phenylsulfonic acid group, naphthylsulfonic acid group, toluylsulfonic acid Examples thereof include aromatic sulfonic acid groups such as groups, and sulfonic acid group-containing aliphatic / aromatic substituents such as benzylsulfonic acid groups, but are not limited thereto. These substituents may be present not only as one type but also as a mixture of a plurality of substituents. These substituents preferably substitute 30% or more of the hydrogen atoms on the imidazole ring nitrogen. If it is less than this, it becomes difficult to exhibit excellent performance in proton conductivity.

The sulfonic acid group in the sulfonic acid group-containing polybenzimidazole compound of the present invention having the N-substituent introduced therein is generally obtained in the form of a salt such as Li or Na. To remove the salt, a commonly used acid treatment can be used. It may be brought into contact with an acid solution in a solid state such as a polymer powder or a film, or may be dissolved in an acid solvent and then put into a non-solvent to be recovered as a free sulfonic acid type polymer. It is also useful to make free sulfonic acid by mild neutralization using an ion exchange resin.

Polybenzimidazole having a sulfonic acid group on the aromatic ring which undergoes the above N-substitution reaction is 3,3'-
Diaminobenzidine, 3,3 ′, 4,4′-tetraaminodiphenyl sulfone, 2,2-bis (3,4-diaminophenyl) propane, 2,2-bis (3,4-diaminophenyl) hexafluoropropane, 3, 3 ', 4,
4'-tetraaminodiphenyl ether, bis (3,
It can be obtained by a polymerization in which an aromatic tetramine selected from 4, -diaminophenoxy) benzene or a derivative thereof and an aromatic dicarboxylic acid containing a sulfonic acid group and an aromatic dicarboxylic acid containing no sulfonic acid group are combined. Examples of the aromatic tetramine derivative include salts with acids such as hydrochloric acid, sulfuric acid and phosphoric acid. The tetramine compound may be used not only in one kind but also in plural kinds at the same time. These aromatic tetramines may contain a known antioxidant such as tin (II) chloride or a phosphorous acid compound, if necessary.

The above-mentioned carboxylic acid group-containing dicarboxylic acid is
An aromatic dicarboxylic acid containing one or two sulfonic acid groups can be selected, and specific examples thereof include 2,5-dicarboxybenzenesulfonic acid and 3,5-dicarboxylic acid. Carboxybenzene sulfonic acid, 4,
6-dicarboxy-1,3-benzenedisulfonic acid,
Examples thereof include sulfonic acid-containing dicarboxylic acids such as 2,5-dicarboxy-1,4-benzenedisulfonic acid and 4,4′-dicarboxy-2,2′-biphenyldisulfonic acid, and derivatives thereof. Examples of the derivative include alkali metal salts such as sodium and potassium, ammonium salts and the like. The structure of the sulfonic acid group-containing dicarboxylic acid is not particularly limited to these. The sulfonic acid group-containing dicarboxylic acids can be introduced not only by themselves but also in the form of copolymerization with dicarboxylic acids not containing sulfonic acid groups. The purity of the dicarboxylic acid containing a sulfonic acid group is not particularly limited, but is preferably 98% or more, more preferably 99% or more. Polybenzimidazole polymerized using a dicarboxylic acid containing a sulfonic acid group as a raw material, as compared with the case of using a dicarboxylic acid not containing a sulfonic acid group, the degree of polymerization tends to be low, the sulfonic acid group It is preferable to use a dicarboxylic acid contained as high purity as possible.

Examples of dicarboxylic acids that can be used with the sulfonic acid group-containing dicarboxylic acids include terephthalic acid,
Isophthalic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, biphenyl dicarboxylic acid, terphenyl dicarboxylic acid, 2,2-bis (4-carboxyphenyl) hexafluoropropane, etc. Dicarboxylic acids can be used and are not limited to those exemplified here. When a dicarboxylic acid containing no sulfonic acid group is used together with a dicarboxylic acid containing a sulfonic acid group, it is necessary that the average number of sulfonic acid groups is 0.5 or more per Ar in the above formula (1).

The polybenzimidazole having a sulfonic acid group on the aromatic ring which undergoes the above N-substitution reaction is, for example, a tetraamine monomer and a dicarboxylic acid monomer as JFWolf.
e, Encyclopedia of Polymer Science and Engineerin
g, 2nd Ed., Vol. 11, P. 601 (1988), and can be synthesized by dehydration and cyclopolymerization using polyphosphoric acid as a solvent. It is also possible to apply polymerization by a similar mechanism using a methanesulfonic acid / phosphorus pentoxide mixed solvent system instead of polyphosphoric acid. In addition, a method such as using a precursor polymer such as a polyamide structure in a reaction with an appropriate organic solvent or a mixed monomer melt, and then converting it to the desired polybenzimidazole structure by a cyclization reaction by an appropriate heat treatment is also used. can do. In order to synthesize a polymer having high heat stability, polymerization using polyphosphoric acid, which is commonly used, is preferable. However, in the polymerization using a dicarboxylic acid containing a sulfonic acid group as in the present invention, in the polymerization that takes a long time as conventionally reported, the thermal stability of the obtained polymer may decrease. is there. Therefore, in the present invention, the polymerization time cannot be unconditionally specified because there is an optimum time depending on the combination of individual monomers, but it is preferable to effectively shorten the polymerization time. As a result, a polymer having a large amount of sulfonic acid groups can also be obtained with high thermal stability.

The sulfonic acid group-containing polyazole compound of the present invention is extruded from a polymerization solution or an isolated polymer,
Fibers and films can be formed by any method such as spinning, rolling, and casting. Above all, it is preferable to mold from a solution dissolved in a suitable solvent. As a solvent to be dissolved, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, N-methyl-2
-Aprotic polar solvents such as pyrrolidone and hexamethylphosphonamide, and strong acids such as polyphosphoric acid, methanesulfonic acid, sulfuric acid, and trifluoroacetic acid can be appropriately selected, but are not limited thereto. A plurality of these solvents may be mixed and used within a possible range. Further, as a means for improving the solubility, a solvent obtained by adding a Lewis acid such as lithium bromide, lithium chloride or aluminum chloride to an organic solvent may be used. The polymer concentration in the solution is preferably in the range of 0.1 to 30% by weight. If it is too low, moldability deteriorates, and if it is too high, workability deteriorates.

As a method for obtaining a molded product from a solution, a known method can be used. For example, the solvent can be removed by heating, drying under reduced pressure, dipping in a polymer non-solvent that is miscible with a solvent that dissolves the polymer, and a molded product of sulfonic acid group-containing polybenzimidazole can be obtained. When the solvent is an organic solvent, it is preferable to distill off the solvent by heating or drying under reduced pressure. When the solvent is a strong acid, it is preferably immersed in water, methanol, acetone or the like. On this occasion,
If necessary, it can be formed into a fiber or a film by being combined with another polymer. When combined with a polybenzazole-based polymer having a similar solubility behavior, it is convenient for good molding.

The preferred method of forming a membrane based on the sulfonic acid group-containing polybenzimidazole compound of the present invention is casting from solution. The solvent can be removed from the cast solution as described above to obtain a sulfonic acid group-containing polybenzimidazole film. It is preferable to remove the solvent by drying in terms of uniformity of the film.
Further, in order to prevent decomposition and deterioration of the polymer and solvent, it is preferable to dry under reduced pressure at the lowest temperature possible. The substrate to cast is a glass plate or Teflon (registered trademark)
A plate or the like can be used. When the viscosity of the solution is high, heating the substrate or the solution and casting at a high temperature lowers the viscosity of the solution, so that the solution can be easily cast. The thickness of the solution at the time of casting is not particularly limited, but 10 to
It is preferably 1000 μm. If it is too thin, the form of the film cannot be maintained, and if it is too thick, a non-uniform film is likely to be formed. More preferably, it is 100 to 500 μm. A known method can be used for controlling the cast thickness of the solution. For example, an applicator, a doctor blade, or the like may be used to make the thickness constant, or a glass petri dish or the like may be used to make the casting area constant to control the thickness by the amount or concentration of the solution. A more uniform film can be obtained from the cast solution by adjusting the removal rate of the solvent. For example, when heating, the evaporation rate can be lowered by lowering the temperature in the first step.
When immersed in a non-solvent such as water, the coagulation rate of the polymer can be adjusted by leaving the solution in air or an inert gas for an appropriate time. The film of the present invention can have any film thickness depending on the purpose, but it is preferably as thin as possible from the viewpoint of ion conductivity. Specifically, it is preferably 200 μm or less, and 50 μm
It is more preferably m or less, and most preferably 20 μm or less.

The phosphonic acid group- or sulfonic acid group-containing polybenzimidazole polymer of the present invention has excellent ionic conductivity, and is suitable for use as an ion exchange membrane in a fuel cell or the like after being formed into a film or a membrane. . Furthermore, by using the polymer structure of the present invention as a main component,
It can also be used as a coating material for a binder resin or the like when producing a bonded body of the ion exchange membrane of the present invention and an electrode.

[0026]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Various measurements were performed as follows. Logarithmic viscosity: Polymer powder was dissolved in concentrated sulfuric acid at a concentration of 0.5 g / dl, and the viscosity was measured using an Ostwald viscometer in a constant temperature bath at 30 ° C. to obtain logarithmic viscosity [ln (ta / tb)].
/ C was evaluated (ta is the number of seconds of dropping the sample solution, tb is the number of seconds of dropping only the solvent, and c is the polymer concentration). Ion conductivity measurement: A platinum wire (diameter: 0.2 mm) was pressed against the surface of a strip-shaped membrane sample on a probe for self-made measurement (made of polytetrafluoroethylene), and a constant temperature and constant humidity oven at 80 ° C and 95% RH ( Nagano Scientific Machinery Works Co., Ltd.
LH-20-01) holds the sample and sets the AC impedance between the platinum wires to SOLARTRON 1250FRE.
It was measured by QUENCY RESPONSE ANALYSER. Measurement was performed by changing the distance between the electrodes, and the electrical conductivity in which the contact resistance between the film and the platinum wire was canceled was calculated by the following formula from the gradient in which the distance between the electrodes and the measured resistance value obtained from the Cole-Cole plot were plotted. Conductivity [S / cm] = 1 / film width [cm] x film thickness [cm] x resistance gap between electrodes [Ω / cm] IR measurement: FTS-40 spectroscope for Biorad and UM for Biorad for microscope
It was measured by a microscopic transmission method using A-300A. NMR measurement: Varian Unity-500 was used for the spectroscope, and DM was used as the solvent.
H-NMR was measured at SO-d6 and a measurement temperature of 80 ° C.

Example 1 3,3 ', 4,4'-tetraaminodiphenyl sulfone
1.500g (5.389 × 10 ^-3 mole), Monosodium 2,5-dicarboxybenzenesulfonate (Purity 99%) 1.445g
(5.389 × 10 ^-3 mole), polyphosphoric acid (phosphorus pentoxide content 7
5%) 20.48 g, phosphorous pentoxide 16.41 g are weighed into a polymerization vessel, flushed with nitrogen, and slowly stirred on an oil bath 1
The temperature was raised to 00 ° C. After holding at 100 ℃ for 1 hour,
The temperature was raised to 150 ° C. for 1 hour, and the temperature was raised to 200 ° C. for 3 hours for polymerization. After completion of the polymerization, the mixture was allowed to cool, water was added to take out the polymer, and washing with water was repeated using a household mixer until the pH test paper became neutral. The obtained polymer was dried under reduced pressure at 80 ° C. overnight. The inherent viscosity of the polymer was 1.52. 500 mg (1.11 × 10 ⁻³ mole) of the obtained polymer was placed in a glass reaction container and vacuum dried on a 100 ° C. oil bath (about 3 hours). Dimethylacetamide (DMA
c) 10 ml was added and dissolved at 150 ° C. After lowering the system to 70 ℃, add 41 mg (5.16 × 10 ^-3 mole) of lithium hydride.
After stirring for 90 minutes, 4.66 ml (= 6.3 g) of propyl bromide (5.12 x 10
^-2 mole) was added, the reaction temperature was set to 80 ° C., and the reaction was continued for 3 hours. After allowing to cool, it was diluted with N-methylpyrrolidone (NMP), and then the white polymer was reprecipitated in 150 ml of THF.
Since the sulfonic acid of the product is a Li salt, the produced polymer was redissolved in methanesulfonic acid and reprecipitated in water to obtain a free acid. The logarithmic viscosity of the obtained polymer was 0.97. The IR spectrum of the obtained polymer is shown in FIG. From 1 H-NMR, it was found that 75% of hydrogen on the imidazole ring nitrogen in the polymer was replaced with a propyl group (Fig. 2). The N-propylated polymer was cast from an NMP solution on a glass plate to make a film. Even if the dried film was treated with hot water at 80 ° C. for 1 hour, the morphology of the film did not change, and when this was used as a measurement sample, the ionic conductivity at 80 ° C. and 95% RH was 0.00051 S / cm.

Example 2 In Example 1, 300 mg of polymer (6.63 × 10 ⁻⁴ mol)
e), lithium hydride 21mg (2.64 × 10 ^-3 mole), DMAc10m
l, using propane sultone 3.23g (2.64 × 10 ^-2 mole),
An N-propyl sulfonic acid compound was obtained. The polymer obtained had an inherent viscosity of 0.57. The IR spectrum of the obtained polymer is shown in FIG. From 1 H-NMR, it was found that 90% of the hydrogen on the imidazole ring nitrogen in the polymer was replaced with a propyl sulfonic acid group. The film morphology did not change even when treated with hot water in the same manner as in Example 1, and the measured ionic conductivity was 0.06 S / cm.

Comparative Example 1 With respect to the polymer polymerized in Example 1, a film was prepared without the N-substitution reaction, and the ionic conductivity was measured in the same manner as in Example 1. The result was 0.00019 S / cm. .

[0030]

Industrial Applicability According to the present invention, it has been possible to enhance the proton conductivity of a polybenzimidazole-based polymer having a sulfonic acid group on an aromatic ring, which has excellent properties such as heat resistance and mechanical properties. It is possible to provide a material exhibiting outstanding performance as a molecular electrolyte.

[Brief description of drawings]

FIG. 1 is an IR spectrum of a N-propylated sample of a polybenzimidazole polymer containing a sulfonic acid group.

FIG. 2 is an H-NMR spectrum of a sample obtained by N-propylating a sulfonic acid group-containing polybenzimidazole polymer.

FIG. 3 is an IR spectrum of a sample obtained by N-propylsulfonic acid oxidation of a polybenzimidazole polymer containing a sulfonic acid group.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // C08L 79:04 C08L 79:04 A (72) Inventor Masahiro Rikukawa 9-11 F, Kougatani, Kanagawa-ku, Yokohama Terms (reference) 4F071 AA58 AA60 AA88 AF42 AH15 BC01 4J043 PA02 QB15 QB21 QB41 RA42 SA08 SB01 TA12 TA17 TA71 TA75 UA041 UA042 UA122 UA131 UB021 UB061 UB121 UB301 XA03 XA08 XB13 A30115B01 Z0114B01 ZB14 ZB14 ZB14 ZB14 ZB14 ZB14 ZB14

Claims (5)

[Claims] 1. A polymer comprising a repeating unit represented by the following general formula (1) as a main component, having a logarithmic viscosity of 0.1 or more as measured in sulfuric acid and being substantially insoluble in water. A characteristic polybenzimidazole compound containing a sulfonic acid group. [Chemical 1] (In the formula, X is —O—, —SO ₂ —, —C (CH ₃ ) ₂ —,
_{-C (CF 3) 2 -,} - OPhO-, selected from a direct bond. Ar is selected from aromatic groups containing 0 to 2 sulfonic acid groups, and the average value of sulfonic acid groups is 0.5 or more per Ar. R is hydrogen, aliphatic having 2 to 12 carbon atoms,
It is selected from aromatic, aliphatic / aromatic substituents and aliphatic sulfonic acids having 2 to 12 carbon atoms, aromatic sulfonic acids, and aliphatic / aromatic sulfonic acid substituents. ) 2. The method according to claim 1, wherein R is hydrogen and has 2 to 2 carbon atoms.
A polybenzimidazole compound containing a sulfonic acid group, which is selected from 12 aliphatic, aromatic and aliphatic / aromatic substituents. 3. The hydrogen according to claim 1, wherein R is hydrogen and the carbon number is 2 to 2.
A polybenzimidazole compound containing a sulfonic acid group, which is selected from 12 aliphatic sulfonic acids, aromatic sulfonic acids, and aliphatic / aromatic sulfonic acid substituents. 4. A molded article comprising the compound according to any one of claims 1 to 3 as a main component. 5. A film comprising the compound according to any one of claims 1 to 4 as a main component.