JP6366494B2 - Sulfone group-containing polyphenylene ether resin - Google Patents

Description

  The present invention relates to a sulfone group-containing polyphenylene ether resin useful as a solid polymer electrolyte membrane.

  A solid polymer electrolyte fuel cell has electrodes connected to both sides of a proton exchange membrane, supplies hydrogen to the anode side of the proton exchange membrane-electrode structure, supplies oxygen or air to the cathode side, and generates power from the potential difference generated at both ends of the electrode. Is done.

  At this time, the solid polymer electrolyte used for the proton exchange membrane must be sufficiently stable electrochemically and mechanically with the proton conductivity, so that it can be used for a long time. A very expensive perfluorocarbon sulfonic acid membrane, typically “Nafion (registered trademark)” manufactured by the Company, has been adopted.

  In addition, the proton exchange membrane must also serve as a gas barrier partition by lowering the gas permeability. When the gas permeability of the proton exchange membrane is high, leakage of anode-side hydrogen to the cathode and leakage of cathode-side oxygen to the anode, that is, cross-leakage occurs. When a cross leak occurs, a so-called chemical short circuit occurs and a good voltage cannot be taken out. There is also a problem that the hydrogen on the anode side reacts with the oxygen on the cathode side to generate hydrogen peroxide, which causes chemical degradation of the proton exchange membrane.

  In order to overcome such drawbacks, a proton exchange membrane in which a sulfone group is introduced into a non-fluorinated aromatic ring-containing polymer having a relatively high gas barrier property has been studied. For example, a sulfonated polyaryl ether sulfone resin (for example, see Patent Document 1), a sulfonated polyether ether ketone resin (for example, see Patent Document 2), a sulfonated polyphenylene ether resin (for example, And non-patent document 1). Among them, a proton exchange membrane based on poly (2,6-dimethyl-1,4 phenylene ether), which is a polyphenylene ether resin used as a general-purpose engineering plastic, is most expected due to its excellent denatureability and economy. One of the materials.

JP 2005-133146 A JP-A-6-93114 US Patent Application Publication No. 2002/0091225 (pages 1-2)

Journal of Applied Polymer Science, Vol. 29 (1984) p. 4017-4027

  However, the sulfone group introduced onto the aromatic ring by the sulfonation reaction of these non-fluorinated aromatic ring-containing polymers generally tends to be easily removed by heat.

  Then, an object of this invention is to provide the sulfone group containing polyphenylene ether resin excellent in durability by suppressing the detachment | leave of the sulfone group by a heat | fever.

  Thermally stable sulfonated polyarylethersulfone obtained by polymerization using a monomer having a sulfone group introduced on an electron-withdrawing aromatic ring as a polymer in which elimination of the sulfone group due to heat is suppressed System compounds have been reported (see, for example, Patent Document 3). However, since the reactivity of the monomer is low, the polymerization reaction time required to obtain the polymer becomes long, and there is a problem in the economics of the polymer.

  As a result of intensive research, the present inventors have partially oxidized the polyphenylene ether resin, thereby suppressing the elimination of the sulfone group introduced onto the aromatic ring, excellent proton conductivity, and low gas permeability. As a result, the inventors have found an electrochemically stable sulfone group-containing polyphenylene ether resin even after heat treatment.

  That is, the present invention is as follows.

[1] A sulfone group-containing polyphenylene ether resin having an oxygen atom content of 30 to 40% by mass and an ion exchange capacity of 0.5 to 3.5 meq / g.

・・・（１）
（式中、Ｒ¹¹、Ｒ¹²、Ｒ¹³は、それぞれ独立して、水素、炭素数１〜４の炭化水素基、ヒドロキシメチル基、ホルミル基、カルボキシ基、ヒドロキシアルキル基、ホルミルアルキル基、カルボキシアルキル基のいずれかである。）；

・・・（２）
（式中、Ｒ²¹、Ｒ²²、Ｒ²³は、それぞれ独立して、水素、炭素数１〜４の炭化水素基、ヒドロキシメチル基、ホルミル基、カルボキシ基、ヒドロキシアルキル基、ホルミルアルキル基、カルボキシアルキル基のいずれかであり、Ｘは、Ｈ、Ｌｉ、Ｎａ、Ｋのいずれかである。） [2] The sulfone group-containing polyphenylene ether resin according to [1], including the components represented by the general formula (1) and the general formula (2).

... (1)
(Wherein R ¹¹ , R ¹² and R ¹³ are each independently hydrogen, a hydrocarbon group having 1 to 4 carbon atoms, a hydroxymethyl group, a formyl group, a carboxy group, a hydroxyalkyl group, a formylalkyl group, a carboxy group, Any of alkyl groups));

... (2)
(Wherein R ²¹ , R ²² and R ²³ are each independently hydrogen, a hydrocarbon group having 1 to 4 carbon atoms, a hydroxymethyl group, a formyl group, a carboxy group, a hydroxyalkyl group, a formylalkyl group, a carboxy group, Any one of alkyl groups, and X is any one of H, Li, Na, and K.)

[3] The sulfonation rate, which is the ratio of the constituent component represented by the general formula (2) to the constituent components represented by the general formula (1) and the general formula (2), is 20 mol% or more. ] Or the sulfone group-containing polyphenylene ether resin according to [2].

[4] The sulfone according to any one of [1] to [3], wherein the ion exchange capacity after annealing at 170 ° C. for 20 minutes is 0.5 meq / g or more and 3.5 meq / g or less. Group-containing polyphenylene ether resin.

  According to the present invention, there is provided a sulfo group-containing polyphenylene ether resin that suppresses elimination of a sulfone group introduced onto an aromatic ring, has excellent proton conductivity, has low gas permeability, and is electrochemically stable even after heat treatment. it can.

  In the present invention, a sulfone group-containing polyphenylene ether resin having an oxygen atom content within a specific range is prepared by oxidation, and the elimination of the sulfone group is suppressed, and gas barrier properties, processability, electrochemical stability, ion conduction are suppressed. The present invention provides a polymer material that is excellent in properties, particularly useful as an electrolyte membrane for fuel cells.

  Hereinafter, a mode for carrying out the present invention (hereinafter also referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

・・・（１）
（式中、Ｒ¹¹、Ｒ¹²、Ｒ¹³は、それぞれ独立して、水素、炭素数１〜４の炭化水素基、ヒドロキシメチル基、ホルミル基、カルボキシ基、ヒドロキシアルキル基、ホルミルアルキル基、カルボキシアルキル基のいずれかである。）
、および一般式（２）

・・・（２）
（式中、Ｒ²¹、Ｒ²²、Ｒ²³は、それぞれ独立して、水素、炭素数１〜４の炭化水素基、ヒドロキシメチル基、ホルミル基、カルボキシ基、ヒドロキシアルキル基、ホルミルアルキル基、カルボキシアルキル基のいずれかであり、Ｘは、Ｈ、Ｌｉ、Ｎａ、Ｋのいずれかである。）
で示される構成成分を含むものが好ましい。 (Sulfone group-containing polyphenylene ether resin)
Although there is no restriction | limiting in particular as a sulfone group containing polyphenylene ether resin of this embodiment, General formula (1)

... (1)
(Wherein R ¹¹ , R ¹² and R ¹³ are each independently hydrogen, a hydrocarbon group having 1 to 4 carbon atoms, a hydroxymethyl group, a formyl group, a carboxy group, a hydroxyalkyl group, a formylalkyl group, a carboxy group, Any of alkyl groups.)
And general formula (2)

... (2)
(Wherein R ²¹ , R ²² and R ²³ are each independently hydrogen, a hydrocarbon group having 1 to 4 carbon atoms, a hydroxymethyl group, a formyl group, a carboxy group, a hydroxyalkyl group, a formylalkyl group, a carboxy group, Any one of alkyl groups, and X is any one of H, Li, Na, and K.)
What contains the structural component shown by these is preferable.

The hydroxyalkyl group in the general formula (1) and the general formula (2) refers to a group composed of a hydroxyl group and a linear, branched, or cyclic alkylene group having 2 to 4 carbon atoms, For example, a hydroxyethyl group, a hydroxypropyl group, etc. are mentioned.
The formylalkyl group refers to a group composed of a formyl group and an alkylene group having 1 to 3 carbon atoms, and examples thereof include a formylmethyl group and a formylethyl group.
A carboxyalkyl group refers to a group composed of a carboxyl group and an alkylene group having 1 to 3 carbon atoms, and examples thereof include a carboxymethyl group and a carboxyethyl group.

The oxygen atom content of the sulfone group-containing polyphenylene ether resin of the present embodiment is 30% by mass or more and 33% by mass or more from the viewpoint of suppressing the elimination of the sulfone group due to heat and improving durability. In addition, it is preferable to suppress the crosslinking reaction of the polyphenylene ether resin and increase the reaction efficiency when obtaining the sulfo group-containing polyphenylene ether resin by the sulfonation reaction of the polyphenylene ether resin described later, and the sulfo group-containing polyphenylene ether resin. From the viewpoint of improving the film forming processability, it is 40% by mass or less, and preferably 35% by mass or less.
The polyphenylene ether resin contains an oxygen atom in its structure. For example, in the case of poly (2,6-dimethyl-1,4 phenylene ether), the oxygen atom content is about 13% by mass. This resin can be oxidized by the method described later, and can be sulfonated by the method described later, so that the oxygen atom content can be 30% by mass or more.
The oxygen atom content of the resin indicates a value after the resin is dried at room temperature (for example, 30 ° C.) for 24 hours unless otherwise specified.

  In addition, the oxygen atom content of the sulfone group-containing polyphenylene ether resin of the present embodiment can be measured using a carbon / hydrogen / nitrogen simultaneous determination apparatus. That is, after a predetermined amount of the sulfone group-containing polyphenylene ether resin is dried, it is quantified by adsorbing and reducing carbon dioxide and water in the cracked gas at a combustion temperature of 1050 ° C. The oxygen atom content can be determined. Examples of the carbon / hydrogen / nitrogen simultaneous determination device include CHN coder MT-6 manufactured by Yanaco Technical Science Co., Ltd.

The ion exchange capacity of the sulfone group-containing polyphenylene ether resin of the present embodiment is 3.5 meq / g or less, preferably 2.8 meq / g or less, for the following reasons, More preferably, it is equal to or less than equivalent / g. That is, by setting the ion exchange capacity within this range, when the sulfone group-containing polyphenylene ether resin is used as a solid polymer electrolyte membrane, swelling under high temperature and high humidity that occurs during operation of the fuel cell is easily reduced. By reducing the swelling of the solid polymer electrolyte membrane, the strength of the solid polymer electrolyte membrane is lowered, wrinkles are generated and the electrode is peeled off from the electrode, and the gas barrier property is lowered. The problem can be improved.
The ion exchange capacity is 0.5 meq / g or more and 0.65 meq / g from the viewpoint of improving the power generation capability of the fuel cell including the solid polymer electrolyte membrane with reduced swelling. g or more, more preferably 1.3 meq / g or more.
The ion exchange capacity of the resin indicates a value after the resin is dried at room temperature (for example, 30 ° C.) for 24 hours unless otherwise specified.

  In addition, the ion exchange capacity can be determined by a conventional method.

The sulfonation rate of the sulfone group-containing polyphenylene ether resin of the present embodiment is not particularly limited, but is 20 mol% or more from the viewpoint of increasing the power generation efficiency of a fuel cell provided with the resin as a solid polymer electrolyte membrane. Preferably, it is more preferably 35% by mole or more, particularly preferably 50% by mole or more, and from the viewpoint of reducing swelling of the solid polymer electrolyte membrane, it is preferably 80% by mole or less, and 75 More preferably, it is at most mol%.
In addition, unless otherwise indicated, the sulfonation rate of resin refers to the value after drying resin for 24 hours at room temperature (for example, 30 degreeC).

  In addition, the sulfonation rate refers to the ratio (ratio by mole) of the component into which the sulfone group is introduced with respect to the entire component (monomer unit) of the base polyphenylene ether resin. For example, when the sulfone group-containing polyphenylene ether resin contains the components represented by the general formula (1) and the general formula (2), the sulfonation rate is expressed by the general formula (1) and the general formula (2). The ratio of the structural component represented by the general formula (2) to the structural component represented by In addition, for example, when the sulfone group-containing polyphenylene ether resin is prepared by partially oxidizing and sulfonating poly (2,6-dimethyl-1,4-phenylene ether), an unsubstituted 2,6 -The value represented by P / (P + Q) x 100 (mol%), where Q is the number of moles of dimethylphenylene oxide units and P is the number of moles of 2,6-dimethylphenylene oxide units substituted with a sulfone group. Point to.

In the sulfone group-containing polyphenylene ether resin of the present embodiment, an effect is obtained that the release of the sulfone group due to heat hardly occurs even under a high temperature condition. And by the said effect, the ion exchange capacity of the resin of this embodiment after having put on high temperature conditions becomes large compared with the ion exchange capacity of the conventional resin after having put on high temperature conditions.
For example, the value of the ion exchange capacity of the sulfone group-containing polyphenylene ether resin of the present embodiment after heat treatment at 170 ° C. for 20 minutes is:
Preferably it is 0.5 meq / g or more, more preferably 1.3 meq / g or more, preferably 3.5 meq / g or less, more preferably 2 meq / g or more. 0.5 meq / g or less, particularly preferably 1.8 meq / g or less.

  The ion exchange capacity of the sulfone group-containing polyphenylene ether resin of the present embodiment is determined by selecting the reaction solution concentration and the dropping amount of chlorosulfonic acid as a sulfonating agent when sulfonating the polyphenylene ether resin. It can adjust suitably so that it may enter. Here, the greater the amount of sulfone groups introduced into the resin, the higher the ion exchange capacity of the resin.

The sulfone group-containing polyphenylene ether resin of the present embodiment can be prepared, for example, by first partially oxidizing the polyphenylene ether resin and then introducing a sulfone group into the partially oxidized resin. it can.
There is also a method of heat-treating a sulfone group-containing polyphenylene ether resin into which a sulfone group has been introduced in advance in an oxygen atmosphere. In this case, since the sulfone group is likely to be removed by heat, as described above, the polyphenylene in an oxygen atmosphere. A method of introducing a sulfone group after heat-treating the ether resin in advance is preferable.

  The polyphenylene ether resin of the present embodiment is not particularly limited, but poly (2,6-dimethyl-1,4-phenylene ether), poly (2,6-dimethyl-1,4-phenylene ether) and poly (2, 2,3,6-trimethyl-1,4-phenylene ether) and mixtures thereof, random copolymers of 2,6-dimethylphenol and 2,3,6-trimethylphenol, poly ( 2,6-dimethyl-1,4-phenylene ether) and poly (2,6-diphenyl-1,4-phenylene ether) block copolymers and mixtures thereof, 2,6-dimethylphenol and 2,6 -Random copolymers with diphenylphenol are preferred.

The intrinsic viscosity of the polyphenylene ether resin is preferably 0.25 dL / g or more, and preferably 0.30 dL / g or more from the viewpoint of enhancing the isolation from the solvent when the sulfone group is introduced and the heat resistance. It is more preferable that the viscosity of the solution at the time of introduction of the sulfonic acid group is not too high, and from the viewpoint of improving handling properties such as stirring and liquid feeding, it is preferably 1.45 dL / g or less, More preferably, it is 0.70 dL / g or less.
In addition, an intrinsic viscosity is calculated | required as follows. That is, 0.5 g of polyphenylene ether resin is dissolved in chloroform to obtain two or more kinds of solutions having different concentrations of 100 mL or more (concentration of 0.5 g / dL or less). Then, using a Ubbelohde viscometer at 25 ° C., the specific viscosities of solutions having different concentrations are measured, and the viscosity when the concentration is 0 is derived from the relationship between the specific viscosity and the concentration. Intrinsic viscosity.

The partial oxidation method of the polyphenylene ether resin used in the present embodiment is not particularly limited as long as the oxygen atom content of the resin can be controlled to 30% by mass or more and 40% by mass or less. For example, the polyphenylene ether resin powder And / or a method of oxidizing a material pelletized by melt kneading using a melt kneader or the like (hereinafter also referred to as “pellet”) by heat treatment using an oven or the like in an oxygen atmosphere. Can be mentioned. There is also a method in which polyphenylene ether resin powder and / or pellets thereof are oxidized by subjecting them to a heat treatment such as melt-kneading in an oxidizing atmosphere (specifically, in the presence of a gas containing oxygen). Can be mentioned.
As reaction conditions for partial oxidation, for example, when a melt kneader is used, the heat treatment temperature can be set to 340 ° C. to 380 ° C., and the heat treatment time can be set to 0.2 minutes to 3 minutes in the air. For example, when an oven is used, the heat treatment temperature can be set to 120 ° C. to 180 ° C. and the heat treatment time can be set to 20 minutes to 200 hours in the air.

Although there is no restriction | limiting in particular as a method of introduce | transducing a sulfone group into the partially oxidized polyphenylene ether resin used for this embodiment, For example, the method of a nonpatent literature 1 can be used. That is, poly (2,6-dimethyl-1,4-phenylene ether) is dissolved in chloroform, chlorosulfonic acid is dropped into this solution and reacted at room temperature to obtain a sulfone group-containing polyphenylene ether resin. Can do. The sulfone group-containing polyphenylene ether resin becomes insoluble in chloroform and precipitates as an amorphous solid as the sulfonation reaction proceeds (as the sulfonation rate increases).
The reaction conditions for sulfonation are: resin concentration in the reaction solution: about 60 g / L, chlorosulfonic acid concentration in the reaction solution: about 28 g / L, and dropping amount of chlorosulfonic acid: about 7 g / min. be able to.

  The method for treating the sulfone group-containing polyphenylene ether resin obtained as a solid is not particularly limited. For example, the resin is dissolved in a solvent such as methanol, ethanol, propanol, dimethyl sulfoxide, and then the solution is used. Examples include a method of casting and drying on a tray to form a film-like solid.

  The sulfone group-containing polyphenylene ether resin of the present embodiment is suitably used for a solid polymer fuel cell, a redox flow battery or the like as a single solid polymer electrolyte membrane or a composite membrane with a conventional perfluorocarbon sulfonic acid membrane. be able to.

  EXAMPLES Hereinafter, although an Example is given and embodiment of this invention is described, this invention is not limited to these Examples.

  Poly (2,6-dimethyl-1,4-phenylene ether) (S201A, manufactured by Asahi Kasei Chemicals Corporation) (Intrinsic viscosity: 0.47 dL / g) as a raw material for the sulfone group-containing polyphenylene ether resins of Examples and Comparative Examples Was used.

  Measurement methods and evaluation methods (1) to (3) of various physical properties in Examples and Comparative Examples are shown below.

(1) Sulfonation rate Using a ¹ H-NMR apparatus (ECA-500, manufactured by JEOL Co., Ltd.), the solvent: DMSO-d ₆ , frequency: 500 MHz, relaxation time: 5 sec, integration of sulfone group-containing polyphenylene ether resin Number of times: NMR measurement was performed 64 times at room temperature. The peak near δ 6.0 ppm is the proton (X) at the 3- or 5-position of the sulfonated 2,6-dimethylphenylene oxide unit, and the peak near δ 6.4 ppm is the unsubstituted 2,6-dimethyl. It is identified as protons (Y) at the 3rd and 5th positions of the phenylene oxide unit, and from the area ratio (ratio of integral values) of the peak, sulfonation rate = area of peak (X) / (area of peak (X) + peak ( The area of Y) / 2) × 100 (mol%) was determined.
The same applies to a partially oxidized sulfone group-containing polyphenylene ether resin.

(2) Oxygen atom content The sulfone group-containing polyphenylene ether resin was dried at 90 ° C for 1 hour, and then about 2 mg of this resin was weighed. Carbon dioxide (CO ₂ ) in cracked gas generated at a combustion temperature of 1050 ° C. using a carbon / hydrogen / nitrogen simultaneous measurement device (CHN coder MT-6, manufactured by Yanaco Technical Science) for the weighed resin. and then determining the concentration of water (H ₂ O), were determined oxygen content of the sulfonic group-containing polyphenylene ether resin (mass%).

(3) Ion exchange capacity 0.02 g of a sulfone group-containing polyphenylene ether resin was immersed in 30 mL of a saturated NaCl aqueous solution at 25 ° C. and left for 30 minutes with stirring. Subsequently, the protons in the saturated NaCl aqueous solution were neutralized and titrated with 0.01N sodium hydroxide aqueous solution using phenolphthalein as an indicator. After neutralization, a sulfone group-containing polyphenylene ether resin in which the counter ion of the ion exchange group was a sodium ion was obtained by filtration. The obtained resin was rinsed with pure water, and then the dry weight after vacuum drying at 160 ° C. was weighed.
Assuming that the amount of sodium hydroxide required for neutralization is M (mmol) and the mass of the sulfone group-containing polyphenylene ether resin in which the counter ion of the ion exchange group is a sodium ion is W (mg), the formula: EW = ( Equivalent mass EW (g / equivalent) was determined by (W / M) -22. Furthermore, the ion exchange capacity (milli equivalent / g) was calculated by taking the reciprocal of the obtained EW value and multiplying it by 1000.

  Hereinafter, each example and each comparative example will be described in detail.

Example 1
About 1 kg of poly (2,6-dimethyl-1,4-phenylene ether) is rotated in the same direction with a twin-screw extruder (ZSK-25, manufactured by Coperion) (screw diameter: 25 mm, L / D = 42, vacuum) The mixture was melt-kneaded with a vent) and a cylindrical pellet having a diameter of about 3 mm and a length of about 3 mm was obtained by a strand cutting method. As melt kneading conditions, nitrogen was introduced into the raw material supply hopper, oxygen concentration in the hopper: 1 to 5% by volume, barrel temperature: 320 ° C., screw rotation speed: 250 rpm, vent vacuum: 700 mmHg, discharge amount: 12 kg / Hour.

  The obtained pellets were oxidized in an oven at 150 ° C. for 20 hours in air.

  Oxidized pellets (30.0 g) were dissolved in chloroform (450 mL), and chlorosulfonic acid (14.1 g) was added dropwise thereto over 20 minutes, and the mixture was reacted at room temperature for 30 minutes. The supernatant was removed from the sulfone group-containing polyphenylene ether resin deposited with the progress of the reaction, and the mixture was washed 3 times with 300 mL of chloroform. The obtained sulfone group-containing polyphenylene ether resin was dissolved in 300 mL of methanol. A polytetrafluoroethylene sheet was laid on a stainless steel tray, applied onto the polytetrafluoroethylene sheet by a cast method, and air-dried at room temperature for 12 hours to obtain a sulfone group-containing polyphenylene ether resin having a thickness of about 4 μm.

The film-like sulfone group-containing polyphenylene ether resin was cut into about 5 mm squares with scissors, transferred to a 3 L plastic tank, and washed with 600 mL of distilled water. The same washing operation was repeated 5 times until the pH of the washing separated water in this washing operation became 5 or more.
The washed film-like sulfone group-containing polyphenylene ether resin was air-dried at room temperature for 24 hours, and then the sulfonation rate, oxygen atom content, and ion exchange capacity were measured by the aforementioned methods (1) to (3).
Further, the washed film-like sulfone group-containing polyphenylene ether resin was heat-treated in an oven at 170 ° C. for 20 minutes (annealing treatment), and then the ion exchange capacity was measured by the above-mentioned method (3).

(Example 2)
Similar to Example 1 except that pellets obtained by melt-kneading poly (2,6-dimethyl-1,4 phenylene ether) were oxidized in an oven at 150 ° C. for 100 hours in an oven, and containing sulfone groups A polyphenylene ether resin was obtained and evaluated.

(Example 3)
Similar to Example 1 except that pellets obtained by melt-kneading poly (2,6-dimethyl-1,4 phenylene ether) were oxidized in an oven at 150 ° C. for 200 hours in an oven, and containing sulfone groups A polyphenylene ether resin was obtained and evaluated. The oxidized pellets were partially insoluble in chloroform (about 20% by mass) during the sulfonation reaction, and operations after the sulfonation reaction were performed using soluble components.

(Comparative Example 1)
The oxygen concentration in the hopper of the co-rotating twin screw extruder is controlled to be less than 1% by volume, and poly (2,6-dimethyl-1,4 phenylene ether) is melt-kneaded to obtain pellets. Except that the oxidation treatment was not performed, a sulfone group-containing polyphenylene ether resin was obtained and evaluated in the same manner as in Example 1.

(Comparative Example 2)
Pellets obtained by melt-kneading poly (2,6-dimethyl-1,4-phenylene ether) were oxidized in an oven at 150 ° C. for 500 hours in air. Although 30.0 g of the obtained pellets subjected to oxidation treatment were intended to be dissolved in 450 mL of chloroform, the pellets did not dissolve and sulfone group-containing polyphenylene ether was not obtained.

  As shown in Table 1, the sulfone group-containing polyphenylene ether resins of Examples 1, 2, and 3 having an oxygen atom content of 30% by mass or more and 40% by mass or less are 20% at 170 ° C. as compared with Comparative Example 1. A high ion exchange capacity is exhibited even after heat treatment for a minute.

According to the present invention, there is provided a sulfo group-containing polyphenylene ether resin that suppresses elimination of a sulfone group introduced onto an aromatic ring, has excellent proton conductivity, has low gas permeability, and is electrochemically stable even after heat treatment. it can.
The sulfone group-containing polyphenylene ether resin of the present invention has a high durability and power generation efficiency as a single solid polymer electrolyte membrane or a composite membrane with a conventional perfluorocarbon sulfonic acid membrane. It can be suitably used for a redox flow battery or the like.

Claims (4)

  A sulfone group-containing polyphenylene ether resin having an oxygen atom content of 30 to 40% by mass and an ion exchange capacity of 0.5 to 3.5 meq / g. The sulfone group containing polyphenylene ether resin of Claim 1 containing the structural component shown by General formula (1) and General formula (2).

... (1)
(Wherein R ¹¹ , R ¹² and R ¹³ are each independently hydrogen, a hydrocarbon group having 1 to 4 carbon atoms, a hydroxymethyl group, a formyl group, a carboxy group, a hydroxyalkyl group, a formylalkyl group, a carboxy group, Any of alkyl groups));

... (2)
(Wherein R ²¹ , R ²² and R ²³ are each independently hydrogen, a hydrocarbon group having 1 to 4 carbon atoms, a hydroxymethyl group, a formyl group, a carboxy group, a hydroxyalkyl group, a formylalkyl group, a carboxy group, Any one of alkyl groups, and X is any one of H, Li, Na, and K.)   The sulfonation rate which is the ratio of the structural component represented by the general formula (2) to the structural component represented by the general formula (1) and the general formula (2) is 20 mol% or more. The sulfone group-containing polyphenylene ether resin described in 1.   4. The sulfone group-containing polyphenylene according to claim 1, wherein the ion exchange capacity after annealing at 170 ° C. for 20 minutes is 0.5 meq / g or more and 3.5 meq / g or less. Ether resin.