JP2002212291A - Sulfonic acid- or phosphonic acid-containing polyimidazole and molded product thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polymeric material usable as a polyelectrolyte improved in ion conductivity and processability by incorporating a sulfonic group or a phosphonic group into a polyimidazole polymer having excellent properties such as heat resistance and mechanical characteristics so as to increase the solubility in N-methy-2-pyrrolidone. SOLUTION: The polymeric material, serving as a polyelectrolyte excellent not only in processability, persistent durability, heat resistance, solvent resistance and mechanical characteristics but also in ion conductivity, is obtained by synthesizing a sulfonic or phosphonic group-containing polyimidazole compound having a solubility in N-methyl-2-pyrrolidone of at least 5 wt.% and a logarithmic viscosity measured in a concentrated sulfuric acid of at least 0.25, and in the case that plural repeating units are contained in the polyimidazole compound, they are bonded mainly randomly and/or alternately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sulfonic acid group or phosphonic acid group-containing polyimidazole resin useful as a polymer electrolyte membrane.

[0002]

2. Description of the Related Art As an example of an electrochemical device using a polymer solid electrolyte as an ion conductor instead of a liquid electrolyte, a water electrolysis tank or a fuel cell can be mentioned. The polymer membrane used for these must be chemically, thermally, electrochemically and mechanically sufficiently stable as well as proton conductivity as a cation exchange membrane. For this reason, a perfluorocarbon sulfonic acid membrane typically represented by "Nafion (registered trademark)" manufactured by DuPont U.S.A. has been used as a material that can be used for a long time. However, if you try to operate under conditions over 100 ° C,
The water content of the film sharply drops, and the softening of the film becomes remarkable. For this reason, in a fuel cell that uses methanol as a fuel, which is expected in the future, performance is reduced due to permeation of methanol in the membrane, and sufficient performance cannot be exhibited. In addition, hydrogen, which is currently being studied, is used as fuel.
It has been pointed out that, even in a fuel cell operated at around 0 ° C., the cost of the membrane is too high as an obstacle to the establishment of fuel cell technology.

In order to overcome such disadvantages, 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 polyarylether 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 using a polymer as a raw material is liable to undergo a desulfonate reaction due to acid or heat, and cannot be said to have sufficient durability for use as an electrolyte membrane for a fuel cell.

As polymers having high heat resistance and high durability, aromatic polyazole polymers such as polyimidazole are known, and a phosphonic acid group or a sulfonic acid group is introduced into these polymers to be used for the above purpose. Can be considered. As such a polymer structure, polybenzimidazole containing sulfonic acid is described in Uno et al., J. Pol.
ym. Sci., Polym. Chem., 15 , 1309 (1977).
3'-diaminobenzidine and 3,5-dicarboxybenzenesulfonic acid or 4,6-dicarboxy-1,3-
What is synthesized from benzenedisulfonic acid is USP-5
In 313895, a compound synthesized using 1,2,4,5-benzenetetramine and 2,5-dicarboxybenzenesulfonic acid as main components is reported. The polymer described in the latter report has been shown to be soluble in dimethylsulfoxide, whereas the polymer described in the former report is partially soluble in dimethylsulfoxide, but N-methyl- Does not dissolve in 2-pyrrolidone (NMP). Thus, even for polymers containing sulfonic acid, the solubility differs for each polymer,
No clear trend was captured. Further, in these reports, no consideration was given to the electrochemical characteristics of the sulfonic acid group, such as for electrolyte membrane applications. These materials have both heat resistance, solvent resistance, mechanical properties and ionic conduction properties, and have not been molecularly designed in consideration of processability. Was inferior to at least one of the characteristics.

[0005] On the other hand, there have been few studies on aromatic polymers containing phosphonic acid from the viewpoint of a polymer electrolyte. As a few examples, USP 5,498,
No. 784, 4,4 '-(2,2,2-trifluoro-1- (trifluoromethyl) ethylidene) bis (2
-Aminophenol) in a polybenzoxazole, wherein 5% to 50% of the dicarboxylic acid component is 3,5-
Polymers have been reported to be dicarboxyphenylphosphonic acids. This polymer is noted for its good solubility and its potential as a composite material, but has not been considered as a polymer electrolyte for battery applications. In fact, it is clear that this polymer is characterized by alcohol solubility and is not suitable for use as an electrolyte membrane for methanol fueled fuel cells. In addition, the ionic conductivity shows only a low value. In addition, JP-A-11-286545
In this publication, a phosphorus-containing polyamide copolymer such as 3,5-dicarboxyphenylphosphonic acid is reported, but only properties focusing on its heat resistance have been investigated. Under acidification conditions used for a fuel cell, this polymer undergoes hydrolysis and cannot be used as an electrolyte membrane.

For the above-mentioned electrolyte membrane, materials having excellent ion conductivity as well as basic properties such as durability stability, heat resistance, solvent resistance, durability stability and mechanical properties have been studied. In addition, whether it is excellent in processability,
This is an important point when considering production at the industrial level. From these facts, looking back on the prior art in which a sulfonic acid group or a phosphonic acid group is introduced into an aromatic polymer, it cannot be said that any material has been provided.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to introduce a sulfonic acid group or a phosphonic acid group into a polyimidazole polymer having excellent properties such as heat resistance and mechanical properties in such a manner as to bring out solubility in NMP. The workability,
An object of the present invention is to obtain a polymer material that can be a polymer electrolyte having excellent ionic conductivity as well as durability stability, heat resistance, solvent resistance, durability stability, and mechanical properties.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, have found that a specific polymer containing a sulfonic acid group or a phosphonic acid group and showing solubility in NMP. With respect to imidazoles, a polymer electrolyte having excellent processability, durability stability, heat resistance, solvent resistance, mechanical properties and ionic conductivity has been obtained.

[0009] That is, the present invention provides a compound having a solubility in NMP of 5
wt% or more, and the logarithmic viscosity measured in concentrated sulfuric acid is 0.1%.
A polyimidazole compound containing a sulfonic acid group or a phosphonic acid group, wherein the polyimidazole compound has a number of repeating units of 25 or more and is mainly and randomly and / or alternately bonded when there are a plurality of repeating units. The molded product of the present invention is obtained by treating in the same manner as in the method of molding a polymer compound. That is, extrusion from a polymerization solution or an isolated polymer, spinning,
It is formed into fibers or films by any method such as rolling and casting. The present invention is a molded product characterized by containing these compounds as a main component, fiber, film,
It can be processed into a sheet-like material or the like, and particularly, by forming a film, particularly effective performance is exhibited.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The term "polyimidazole containing a sulfonic acid group or a phosphonic acid group" as used in the present invention refers to aromatic polyimidazoles containing a sulfonic acid group or a phosphonic acid group, and compositions and copolymers in which they are mixed. Generally, it can be represented by a repeating unit structure as shown in the following formula.

[0011]

Embedded image (In the general formula 1, R represents a tetravalent aromatic group capable of forming an imidazole ring. R ′ represents a divalent aromatic group,
It represents an aliphatic group or an alicyclic group, and has a sulfonic acid group or a phosphonic acid group in all or a part of R ′.
Each of R and R ′ may be a single ring, a combination of a plurality of aromatic rings, or a condensed ring, and may have a stable substituent other than sulfonic acid or phosphonic acid.
Further, the aromatic ring of R and R 'may have a heterocyclic structure in which N, S, O, etc. are present.

Further, it may contain a repeating unit represented by the following formula together with the general formula 1.

Embedded image (Here, R "represents a trivalent aromatic group capable of forming an imidazole ring.)

The route for synthesizing the polyimidazole containing a sulfonic acid group or phosphonic acid group of the present invention represented by the above general formula 1 is not particularly limited, but usually, a tetravalent aromatic compound capable of forming an imidazole ring represented by R in the formula The compound can be synthesized by reacting a compound selected from aromatic tetramine and a derivative thereof forming a group unit with a compound selected from a dicarboxylic acid and a derivative thereof forming a divalent group represented by R ′. At that time, by using a dicarboxylic acid containing a sulfonic acid or a phosphonic acid among the dicarboxylic acids to be used, a sulfonic acid or a phosphonic acid group can be introduced into the obtained polyimidazole.

Specific examples of the aromatic tetramine include 1,1,
2,4,6-tetraaminobenzene, 3,3′-diaminobenzidine, 3,3 ′, 4,4′-tetraaminodiphenylsulfone, 2,2-bis (3,4-diaminophenyl) propane, 2, Examples include, but are not limited to, 2-bis (3,4-diaminophenyl) hexafluoropropane and bis (3,4, -diaminophenoxy) benzene. Examples of these derivatives include salts with acids such as hydrochloric acid, sulfuric acid and phosphoric acid. A plurality of these compounds can be used simultaneously. These aromatic tetramines may contain a known antioxidant such as tin (II) chloride or a phosphorous acid compound as needed.

The sulfonic acid group-containing dicarboxylic acid may be selected from aromatic dicarboxylic acids containing one to four sulfonic acid groups. Specific examples thereof include:
For example, 2,5-dicarboxybenzenesulfonic acid,
3,5-dicarboxybenzenesulfonic acid, 4,6-dicarboxy-1,3-benzenedisulfonic acid, 2,5-
Examples thereof include sulfonic acid-containing dicarboxylic acids such as dicarboxy-1,4-benzenedisulfonic acid and derivatives thereof. Examples of the derivative include alkali metal salts such as sodium and potassium, and ammonium salts. 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 alone but also in the form of a copolymer together with a sulfonic acid group-free dicarboxylic acid. The purity of the dicarboxylic acid having a sulfonic acid group is not particularly limited, but is preferably 98% or more, and more preferably 99% or more. Polyimidazole polymerized from a dicarboxylic acid containing a sulfonic acid group as a raw material has a tendency to have a lower degree of polymerization than when a dicarboxylic acid containing no sulfonic acid group is used, and therefore contains a sulfonic acid group. Preferably, the dicarboxylic acid used has as high a purity as possible.

Specific examples of the phosphonic acid-containing dicarboxylic acid include, for example, 2,5-dicarboxyphenylphosphonic acid, 3,5-dicarboxyphenylphosphonic acid, 2,5
Examples thereof include phosphonic acid-containing dicarboxylic acids such as -bisphosphonoterephthalic acid, and derivatives thereof, but are not limited thereto, but the phenylphosphonic acid type shown here is preferable. The phosphonic acid-containing dicarboxylic acids can be introduced in the form of a copolymer together with the dicarboxylic acid containing no phosphonic acid, in addition to those alone. The purity of the dicarboxylic acid containing a phosphonic acid group is not particularly limited, but is preferably 97% or more, and more preferably 98% or more. Polyimidazole polymerized from a dicarboxylic acid containing a phosphonic acid group as a raw material contains a phosphonic acid group since the degree of polymerization tends to be lower than when a dicarboxylic acid containing no phosphonic acid group is used. Preferably, the dicarboxylic acid used has as high a purity as possible.

Examples of the dicarboxylic acids which can be used together with the above-mentioned sulfonic acid group-containing dicarboxylic acid or phosphonic acid group-containing dicarboxylic acid include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, biphenyl dicarboxylic acid, General dicarboxylic acids reported as polyester raw materials, such as phenyldicarboxylic acid and 2,2-bis (4-carboxyphenyl) hexafluoropropane, can be used, and are not limited to those exemplified here. . When a dicarboxylic acid containing no sulfonic acid group or phosphonic acid group is used, it is premised that the sulfonic acid group-containing dicarboxylic acid or phosphonic acid group-containing dicarboxylic acid is used within a range showing the solubility of the obtained polymer in NMP. However, the effect as an ionic group of sulfonic acid or phosphonic acid can be clarified by setting the content to 20 mol% or more of the total dicarboxylic acid. In order to achieve the outstanding effect of the ionic group, 5
More preferably, it is 0 mol% or more.

The route for introducing the polyimidazole unit represented by the above general formula 2 is not particularly limited, but usually, R
Can be obtained by polymerization of a compound selected from aromatic carboxylic acids having two amino groups at the ortho position forming a trivalent aromatic group unit capable of forming an azole ring and derivatives thereof.

The method of synthesizing these sulfonic acid group or phosphonic acid group-containing polyimidazole compounds from the above monomers is not particularly limited, but is described in JFWolfe, Encyc.
lopedia of Polymer Science and Engineering, 2nd E
d., Vol. 11, P. 601 (1988), and can be synthesized by dehydration and cyclopolymerization using polyphosphoric acid as a solvent. Also, instead of polyphosphoric acid, methanesulfonic acid /
Polymerization by a similar mechanism using a phosphorus pentoxide mixed solvent system can also be applied. In addition, a method in which a precursor polymer such as a polyamide structure is prepared in a suitable organic solvent or by a reaction of a mixed monomer melt and then converted to a target polyimidazole structure by a cyclization reaction by a suitable heat treatment or the like is also used. be able to. In order to synthesize a polymer having high thermal stability, polymerization using polyphosphoric acid which is generally used is preferable. However, in a polymerization that takes a long time as conventionally reported, in a system containing a phosphonic acid or sulfonic acid-containing monomer, the thermal stability of the obtained polymer may be reduced. For this reason, in the present invention, the polymerization time cannot be specified unconditionally because there is an optimum time depending on the combination of the individual monomers, but it is preferable to effectively shorten the polymerization time. As a result, a polymer having a large amount of phosphonic acid groups or sulfonic acid groups can be obtained with high thermal stability. Although the molecular weight of these phosphonic acid group and sulfonic acid group-containing polyimidazole is not particularly limited, it is 1,000 to 1,000,000.
000 is preferred. Substantially, the molecular weight of the polymer can be evaluated by the solution viscosity, and the logarithmic viscosity measured in concentrated sulfuric acid is preferably 0.25 or more. If the molecular weight is too low, there is a possibility that the compound will fall off the molded product, such as dissolution in water. If the molecular weight is too high, molding becomes difficult. Therefore, the solution viscosity is preferably smaller than 10. In addition, when a plurality of repeating units are bonded mainly and / or alternately, the polymer has a characteristic of exhibiting stable performance as a polymer electrolyte membrane.

The phosphonic acid or sulfonic acid group-containing polyimidazole compound of the present invention can be extruded from a polymerization solution or an isolated polymer and formed into fibers or films by any method such as spinning, rolling and casting. Among them, molding from a solution dissolved in an appropriate solvent is preferable. As the solvent for dissolving, a suitable solvent can be selected from aprotic polar solvents such as N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, NMP, and hexamethylphosphonamide, but are not limited thereto. Absent. Of course, the phosphonic acid group or sulfonic acid group-containing polyimidazole of the present invention is characterized by having high solubility in NMP,
It is also suitable for use as an MP solution. These solvents may be used as a mixture of two or more as much as possible. As a means for improving 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 concentration of the polymer 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, processability deteriorates.

A known method can be used for obtaining a molded body from the solution. For example, by heating, drying under reduced pressure, or dipping in a polymer non-solvent that is miscible with a solvent that dissolves the polymer, the solvent can be removed to obtain a molded article of a polyimidazole containing a phosphonic acid group or a sulfonic acid group. When the solvent is an organic solvent, the solvent is preferably distilled off by heating or drying under reduced pressure. When the solvent is a strong acid,
It is preferable to immerse in water, methanol, acetone or the like. At this time, if necessary, it can be formed into a fiber or a film in a form of a composite with another polymer. When combined with a polybenzazole-based polymer having a similar solubility behavior, it is convenient for good molding.

A preferred method for forming a membrane comprising the phosphonic acid group or sulfonic acid group-containing polyimidazole compound of the present invention as a main component is casting from a solution. The solvent can be removed from the cast solution as described above to obtain a phosphonic acid group or sulfonic acid group-containing polyimidazole film. It is preferable to remove the solvent by drying from the viewpoint of the uniformity of the film. Further, in order to avoid decomposition and deterioration of the polymer and the solvent, it is preferable to dry under reduced pressure at a temperature as low as possible. As a substrate to be cast, a glass plate, a Teflon (registered trademark) plate, or the like can be used. When the viscosity of the solution is high, if the substrate or the solution is heated and cast at a high temperature, the viscosity of the solution is reduced and the solution can be easily cast. The thickness of the solution at the time of casting is not particularly limited, but is preferably from 10 to 1000 μm. If it is too thin, it will not be able to maintain its form as a membrane,
If it is too thick, a non-uniform film tends 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,
The thickness can be controlled by using an applicator, a doctor blade, or the like, or controlling the thickness by controlling the amount or concentration of the solution with a constant casting area using a glass petri dish. A more uniform film can be obtained from the cast solution by adjusting the removal rate of the solvent. For example, when heating, it is possible to lower the evaporation rate at the initial stage by lowering the temperature. 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 membrane of the present invention can have any thickness depending on the purpose, but is preferably as thin as possible from the viewpoint of ion conductivity. Specifically, it is preferably 200 μm or less, more preferably 50 μm or less, and most preferably 20 μm or less.

The sulfonic or phosphonic acid-containing polyimidazole polymer of the present invention is characterized by being soluble in NMP at 5 wt% or more. Polyazole-based polymers generally have low solubility and are often soluble only in strongly acidic solvents. In the case of forming a polymer electrolyte membrane, if the membrane is formed by a wet method from a strongly acidic solution, the membrane structure tends to be non-uniform, and it is difficult to form a membrane that maintains stable performance. On the other hand, a polymer soluble in an organic solvent such as NMP as in the present invention can be formed into a film by a dry method, and a uniform polymer electrolyte membrane exhibiting stable membrane performance over a long period of time can be produced. Therefore, even if it is contained in the polyimidazole structure containing a sulfonic acid group or a phosphonic acid group as described above, if it does not dissolve in NMP at 5 wt% or more, the object of the present invention is achieved. Can not.

The phosphonic acid group or sulfonic acid group-containing polyimidazole polymer of the present invention has excellent ion conductivity, and is therefore suitable for use as an ion exchange membrane for a fuel cell or the like in the form of a film or film. Furthermore, by using the polymer structure of the present invention as a main component, it can be used as a coating material such as a binder resin when the bonded body of the ion exchange membrane and the electrode of the present invention is produced.

Further, the film according to the present invention is excellent in durability, solvent resistance and mechanical properties. For example, in terms of durability, a thermal decomposition temperature in thermogravimetry is 300 ° C. or higher, and a decrease in molecular weight due to hydrolysis in hot water is small. With solvent resistance, there is little swelling in an acidic aqueous solution or hot water, and with regard to mechanical properties, there is no fear of breakage or the like in handling the film even when the film is thin.

[0026]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. In addition, various measurements were performed as follows. Ion conductivity measurement: Probe for self-made measurement (made by Teflon)
Platinum wire (diameter: 0.2 mm) on the surface of the strip-shaped film sample
And a constant temperature / humidity oven at 80 ° C and 95% RH (Nagano Kagaku Kikai Seisakusho Co., Ltd., LH-20-01)
The sample was held inside, and the AC impedance at 10 KHz between the platinum wires was
Measured by QUENCY RESPONSE ANALYSER. The measurement was performed while changing the distance between the electrodes, and the conductivity in which the contact resistance between the film and the platinum wire was canceled was calculated by the following equation from the gradient plotting the distance between the electrodes and the measured resistance value. Conductivity [S / cm] = 1 / film width [cm] x film thickness [cm] x resistance gradient [Ω / cm] Polymer logarithmic viscosity: Polymer powder is dissolved in concentrated sulfuric acid at a concentration of 0.5 g / dl. The viscosity was measured using an Ostwald viscometer in a thermostat at 30 ° C., and the logarithmic viscosity [ln (ta)
/ Tb)] / c (ta is the number of seconds the sample solution has fallen, tb is the number of seconds that the solvent alone has fallen, and c is the polymer concentration). Evaluation of solvent resistance: When the film was immersed in boiling water for 1 hour, it was visually determined whether or not the morphology of the film changed due to swelling or dissolution. Durability: 100 ° C in ampoule containing polymer powder
And left for 3 days. The durability was evaluated from the change in the measured viscosity value before and after the treatment. IR measurement: Biorad FTS-40 for spectrometer, Biorad UM for microscope
It was measured by a microscopic transmission method using A-300A. TGA measurement: TGA measurement was carried out using a TGA-50 manufactured by Shimadzu Corporation, and about 5 mg of a sample containing a sulfonic acid or phosphonic acid-containing polymer having substantially no salt formed was measured in an argon atmosphere. The temperature was raised to 150 ° C. at 10 ° C./min, held for 30 minutes to remove moisture in the sample, and further measured at 600 ° C. at 10 ° C./min. 200
The temperature at which 3% of the weight of the sample was reduced based on the weight of the sample at the time of the temperature rise at the temperature was defined as a 3% weight reduction temperature.

Example 1 1.500 g (5.389 × 10 ⁻³ mole) of 3,3 ′, 4,4′-tetraaminodiphenylsulfone (abbreviation: TAS), monosodium 3,5-dicarboxybenzenesulfonate (abbreviation:
SIA, 98% purity) 0.954 g (3.557 × 10 −3 mole), terephthalic acid (abbreviation: TPA) 0.304 g (1.836 × 10 −3 mole), polyphosphoric acid (phosphorus pentoxide content 75%) 20.48 g, phosphorus pentoxide 1
Weigh 6.41 g into a polymerization vessel. Pour nitrogen and raise the temperature to 100 ° C while stirring slowly on an oil bath. 10
After maintaining at 0 ° C. for 1 hour, the temperature was raised to 140 ° C. for 1 hour, and the temperature was raised to 200 ° C. for 4 hours. After completion of the polymerization, the mixture was left 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 logarithmic viscosity of the polymer was 1.31. The IR spectrum of the polymer is shown in FIG. 400 mg of the obtained polymer and NMP4
While stirring, ml was heated to 170 ° C. on an oil bath to dissolve. On a hot plate, about 300 on a glass plate
It was cast to a thickness of μm and NMP was evaporated. The film was peeled off from the glass plate, dried under reduced pressure at 80 ° C. overnight, and then immersed in acetone to remove the solvent to prepare a film for measuring ion conductivity. The ionic conductivity at 80 ° C. and 95% RH was 0.0047 S / cm, and the measured ionic conductivity maintained stable performance for a long time. The film was immersed in boiling water for 1 hour, but no change in morphology was observed.
Further, the logarithmic viscosity after immersion treatment in water at 100 ° C. for 3 days was 1.30, and no change was observed from that before the treatment. Even when a thin film having a thickness of about 10 micrometers was produced, the film was not broken in the above-described various evaluations. The 3% weight loss onset temperature in TGA was 465 ° C.

Example 2 In Example 1, SIA and T were used as dicarboxylic acid components.
Change the mixing ratio of PA to 34:66 (molar ratio), and
(5.389 × 10 −3 mole), and polymerization and various measurements were carried out in the same manner as in Example 1 except that the charge was carried out. The logarithmic viscosity of the polymer is 1.16, and the ionic conductivity is 0.0029.
S / cm, and the measured ionic conductivity maintained stable performance for a long time. The film was immersed in boiling water for 1 hour, but no change in morphology was observed. 100 ° C
The logarithmic viscosity after immersion treatment in water for 3 days was 1.11, and no change was observed from that before treatment. Also thickness 1
Even when a thin film having a thickness of about 0 μm was produced, the film was not broken in the above various evaluations. The onset temperature for 3% weight loss in TGA was 491 ° C.

Comparative Example 1 1.445 g (5.389 × 10 −3 mol) of SIA as a dicarboxylic acid component
Polymerization and various measurements were carried out in the same manner as in Example 1 except that the components were charged as in e). The logarithmic viscosity of the obtained polymer was 1.99. 400 mg of polymer obtained
170 ° C on an oil bath while stirring 4 ml of NMP
Was continued, but the dissolution of the polymer did not proceed. T
The 3% weight loss onset temperature in GA was 467 ° C.

Example 3 Monosodium 2,5-dicarboxybenzenesulfonate (abbreviation: STA, purity: 99%) was used in place of SIA, and the evaluation was performed in the same manner as in Example 1 by changing the mixing ratio of STA and TPA. . In each case, a good film could be prepared from the NMP solution, and the ionic conductivity of each sample maintained stable performance for a long time, and the morphology of the film was well maintained. Table 1 shows various measurement results. FIG. 2 shows an IR spectrum of a film having a composition of TPA / STA = 66/34.

[0031]

[Table 1]

Example 4 Instead of SIA, 3,5-dicarboxyphenylphosphonic acid (abbreviation: DCP, purity 98%) was used.
Evaluation was performed in the same manner as in Example 1 except that the mixing ratio of PA was changed. In each case, a good film could be prepared from the NMP solution, and the ionic conductivity of each sample maintained stable performance for a long time, and the morphology of the film was well maintained. Table 2 shows various measurement results.

[0033]

[Table 2]

Comparative Example 2 1.326 g (5.389 × 10 −3 mol) of DCP as a dicarboxylic acid component
Polymerization and various measurements were carried out in the same manner as in Example 4 except that the components were charged as in e). The logarithmic viscosity of the obtained polymer was 0.92. 400 mg of polymer obtained
170 ° C on an oil bath while stirring 4 ml of NMP
Was continued, but the dissolution of the polymer did not proceed. T
The 3% weight loss onset temperature in GA was 494 ° C.

Example 5 In Example 1, tin (II) chloride was replaced with TAS during polymerization.
The polymer was obtained by adding so as to be 1 mol% with respect to the above, and evaluated similarly. The logarithmic viscosity of the polymer is 1.44 dl / g
was. The ionic conductivity at 80 ° C. and 95% RH is 0.1.
0050 S / cm, the measured ionic conductivity maintained stable performance over a long period of time, and the morphology of the membrane was well maintained. I dipped the film in boiling water for 1 hour,
No morphological changes were observed. The logarithmic viscosity after immersion treatment in 100 ° C. water for 3 days is 1.41;
No change from before treatment was observed.

Comparative Example 3 A polymer was synthesized in Example 1 using 3,3′-diaminobenzidine instead of TAS. The logarithmic viscosity of the obtained polymer was 1.23, but the polymer was NM
It did not dissolve in P and could not produce an evaluable film. The onset temperature for 3% weight loss in TGA is 4
69 ° C.

Comparative Example 4 In Example 2, 1.05 g of TAS (3.773 × 10 ⁻³ mol
e), after polymerizing TPA as 0.598 g (3.557 × 10 ⁻³ mole), the polymerization solution was once cooled, and then TAS was further reduced to 0.45 g.
g (1.616x10-3mole), the STA 0.491g (1.832x10 ^-3 mole)
Was added to synthesize a block copolymer having TPA / STA = 66/34. The logarithmic viscosity of the obtained polymer is 0.1.
77, and a film could be produced by the same method. However, the ionic conductivity at 80 ° C. and 95% RH is 0.0003 S / cm, which is lower than that of the polymer of Example 2 having the same copolymerization ratio. The value was one digit smaller. The onset temperature for 3% weight loss in TGA was 472 ° C.

Comparative Example 5 In Example 1, 1.510 g of 3,3′-diamino-4,4′-dihydroxydiphenyl sulfone was used instead of TAS.
(5.387 × 10 ⁻³ mole) to synthesize a similar polybenzoxazole-based polymer. The logarithmic viscosity of the obtained polymer was 0.44. After the polymer was immersed in water at 100 ° C. for 3 days, the logarithmic viscosity was measured and found to be 0.19. The 3% weight loss onset temperature in TGA was 393 ° C.

Comparative Example 6 A polymer was synthesized in the same manner as in Example 1 except that TAS was changed to 1.45 g. The logarithmic viscosity of the obtained polymer was 0.20, and the formed film was brittle.

For comparison, Examples 1 and 2 and Comparative Examples 1 and 2
Table 3 shows the results of 2, Example 5, and Comparative Examples 3, 4, 5, and 6.

[0041]

[Table 3]

[0042]

The polymer of the present invention, which is excellent in processability, durability stability, heat resistance, solvent resistance, mechanical properties and ionic conductivity, provides a material which exhibits outstanding performance as a polymer electrolyte for fuel cells and the like. Can be provided.

[Brief description of the drawings]

FIG. 1: IR of sulfonic acid-containing polybenzimidazole synthesized from TAS and SIA / TPA (66/34)
Spectrum

FIG. 2: IR spectrum of sulfonic acid-containing polybenzimidazole synthesized from TAS and STA / TPA (34/66)

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H01M 8/02 H01M 8/02 P // C08L 79:04 C08L 79:04 (72) Inventor Shiro Hamamoto Otsu City, Shiga Prefecture 2-1-1 Katata Inside Toyobo Co., Ltd. Research Laboratory (72) Inventor Hiroshi Tatemori 2-1-1 Katata Katsuta, Otsu City, Shiga Prefecture Inside Toyobo Co., Ltd. Research Laboratory (72) Inventor Satoshi Takase Otsu, Shiga Prefecture 2-1-1, Ichikata F-term (reference) in Toyobo Co., Ltd. Research Laboratory 4D006 GA41 MA01 MA03 MA12 MA13 MB13 MB15 MB16 MC57X MC74X NA01 PB70 PC80 4F071 AA58 AA88 AF05 AF45 AF57 AH15 FA05 FC01 FD04 4J043 PA41 RA04 PC186 QB SA08 SB01 TA12 TA75 TA79 TB01 UA121 UA122 UA131 UB011 UB061 UB301 XA11 ZA23 ZB11 5G301 CA30 CD01 5H026 AA06 CX04

Claims (3)

[Claims] (1) When the solubility in N-methyl-2-pyrrolidone is 5 wt% or more, the logarithmic viscosity measured in concentrated sulfuric acid is 0.25 or more, and when there are a plurality of repeating units, it is mainly random and / or alternating. A polyimidazole compound containing a sulfonic acid group or a phosphonic acid group, which is chemically bonded. 2. A molded article comprising the compound according to claim 1 as a main component. 3. A film comprising the compound according to claim 1 as a main component.