JPH0617471B2 - Sulfonated polyaryl ether polymer and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a sulfonated polyarylether-based polymer, and more particularly to a sulfonated polyarylethersulfone or / and a sulfonated polyaryletherketone and a method for producing the same. It is a thing.

(b) Prior art JP-A-55-36296 discloses a formula, The repeating unit represented by A sulfonated polyaryl ether ketone in which a polymer having a repeating unit represented by the formula (1) is controlled and sulfonated is disclosed. Since it has hydrophilicity and has high strength even when containing a considerable amount of water, It is described that it is useful as an ultrafiltration membrane and can also be used as an insulating material for conductors.

Similarly, in Japanese Patent Laid-Open No. 55-48222, the formula, And the repeating unit There is disclosed a sulfonated polyarylethersulfone obtained by controlled sulfonation of a polymer having a repeating unit represented by the formula (1), which has high hydrophilicity and high strength even when it contains a considerable amount of water. , There is a description that it is useful as an ultrafiltration membrane.

In addition, Japanese Patent Publication No. 53-13679 discloses a formula There is a disclosure about a sulfonated polyaryl ether sulfone that sulfonates a non-sulfonated polysulfone composed of a unit represented by the following, and there is a description that it is particularly useful as a membrane for reverse osmosis.

(c) Problems to be Solved by the Invention However, since the sulfonated polymer disclosed in Japanese Patent Publication No. 53-13679 has to use a strong sulfonating agent such as chlorosulfonic acid, industrially. It is disadvantageous in production, and the membrane properties of the obtained sulfonated polymer are not always satisfactory.

On the other hand, Japanese Patent Laid-Open Nos. 55-36296 and 5
The sulfonated polymer disclosed in Japanese Patent Laid-Open No. 5-48222 is advantageous in that it can be sulfonated even with concentrated sulfuric acid, but there is a problem that the reaction takes a long time. Further, since the membrane strength of the obtained sulfonated polymer in the water-containing state is not always sufficient, the membrane life may be short in some cases, and this point needs to be further improved.

(d) Means for Solving the Problems The present invention has been earnestly studied for the purpose of providing a novel sulfonated polyarylether polymer having good productivity and excellent membrane properties, It has been completed.

That is, the sulfonated polyaryl ether polymer of the present invention has the formula (In the formula, n is an integer of 1 or more, and X ₁ and X ₂ are CO or SO.
Represents ₂ . ) The repeating unit A represented by
And expression A sulfonated polymer having a repeating unit B represented by the following formula, wherein the ratio of the repeating unit A to the repeating unit B when the repeating unit B is contained is such that the repeating unit A is 1 to 99 mol% and the repeating unit B is 99-1 mol% and the formula in repeating unit A The sulfonation degree is such that the sulfonated product has a hydrophilicity corresponding to the degree of water absorption of 2 wt% of water absorbed at room temperature to complete dissolution in water. Furthermore, the logarithmic viscosity, which is an index of the degree of condensation or the molecular weight of the polymer, is at least 0.2 (0.5 g polymer / 1
It is 100 ml N-methylpyrrolidone, 30 ° C.).

In the present invention, the formula in repeating unit A Only the site represented by is sulfonated, and is sulfonated is that only the above-mentioned site in all the molecules in the polymer is sulfonated, and a part of all the molecules in the polymer. It is meant to include those in which only the above-mentioned site is sulfonated.

The degree of sulfonation is specified by the degree of water absorption described below.

The method for producing the sulfonated polyaryl ether polymer of the present invention is (In the formula, n is an integer of 1 or more, and X ₁ and X ₂ are CO or SO.
Represents ₂ . ) The repeating unit A represented by
And expression The polymer having the repeating unit B shown in 1) is sulfonated with concentrated sulfuric acid.

The present invention will be described in detail below.

The polyaryl ether-based polymer before sulfonation of the present invention has the formula The repeating unit A represented by is included as an essential unit.

Here, n represents a number of 1 or more, and particularly preferably in the range of 1 to 5.

In this case, n different repeating units A in the same polymer molecule
The inclusion of is not only problematic, but also improves the membrane characteristics in the application of the separation membrane, which is rather preferable. This is presumably because when the same polymer contains n different repeating units A, the crystallinity of the molecule is disturbed, and more excellent flexibility is achieved when a film is formed.

Further, when a polyarylether-based polymer is produced by mixing it in a theoretical amount such that n becomes 1, most of the obtained polymer is n = 1, but since the polymerization reaction occurs in a competitive reaction, A polymer in which n is larger than 1 can be obtained, but it is acceptable for the above reason.

In the above formula, X ₁ and X ₂ represent CO or SO _2, and either X ₁ or X ₂ in the same molecule may be CO or SO ₂ , or _one of X ₁ and X ₂ is CO. , And the other may be SO ₂ .

The polyaryl ether-based polymer before sulfonation used in the present invention has the following formula in addition to the repeating unit A described above. It may have a repeating unit B represented by

This unit B contributes to the adjustment of the sulfonation degree and the membrane characteristics.

When the repeating unit B is contained, the ratio between the repeating unit A and the repeating unit B is selected from a wide range such that the repeating unit A is 1 mol% or more and the repeating unit B is 99 mol% or less. A more preferable range is 95 to 5 mol% of repeating unit A and 5 to 95 mol% of repeating unit B.

The polyaryl ether-based polymer before sulfonation is treated with a suitable p-, in the presence of a sulfone or sulfoxide solvent.
o- or m-halophenol, 4,4'-dihydroxybenzophenone, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dichlorodiphenyl sulfone, 4,4'-difluorodiphenyl sulfone, 4,4'-dichlorobenzophenone , Dihydroxyphenol, p- (p-chlorophenylsulfonyl) phenol, and the like are subjected to a condensation reaction with an alkali metal carbonate or a bicarbonate to adjust.

Here, as the sulfone or sulfoxide solvent, dimethylsulfoxide, dimethyl sulfone, diethyl sulfoxide, diisopropyl sulfone, diphenyl sulfone,
Examples thereof include tetrahydrothiophene-1,1-dioxide (that is, sulfolane), tetrahydrothiophene-1-monooxide, and the like. With these, benzene, toluene,
Organic solvents such as xylene, chlorobenzene, dichlorobenzene, heptane, diphenyl ether, and anisole may be used together.

Examples of the alkali metal in the alkali metal carbonate or bicarbonate include lithium, sodium, potassium, and cesium. Particularly, sodium and potassium are highly practical in terms of reactivity and cost.

The sulfonation of the polyaryl ether polymer thus prepared can be achieved simply by dissolving the above polyaryl ether polymer in concentrated sulfuric acid and stirring. Although the reaction can be carried out under cooling or under heating, it is usually carried out at room temperature. Even in the reaction at room temperature, a reaction time of several tens to several hours is sufficient. An appropriate solvent can be used together with concentrated sulfuric acid.

The sulfone group introduced into the polymer by sulfonation is represented by the formula —SO ₃ M, where M represents hydrogen, an alkali metal or tetraalkylammonium. For example,
After sulfonation of the polyarylether polymer,
A polymer having a free sulfonic acid group can be obtained by washing with water and drying. By treating the sulfonated polymer with an aqueous solution of an alkali metal hydroxide or an alkali metal alcoholate, a methanol solution, an ethanol solution or the like, the free sulfonic acid group can be converted into an alkali metal salt. Examples of the alkali metal hydroxide include sodium hydroxide, potassium hydroxide, lithium hydroxide and the like, and examples of the alkali metal alcoholate include sodium methylate, potassium methylate, sodium ethylate and potassium ethylate. Further, when treated with an aqueous solution of tetraalkylammonium hydroxide, for example, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, or a methanol or ethanol solution, the corresponding tetraalkylammonium salt is obtained. Can also be

When the polyarylether-based polymer is composed of only the repeating unit A, a part or all of the unit A is sulfonated depending on the sulfonation conditions during the sulfonation.

When the polyarylether-based polymer contains the repeating unit B in addition to the repeating unit A, only the repeating unit A is sulfonated by the sulfonation treatment, and the repeating unit B is substantially not sulfonated. Therefore, the sulfonation degree can be arbitrarily adjusted by appropriately selecting the ratio of the repeating unit A and the repeating unit B in the polymer.

The degree of sulfonation is preferably selected so that the obtained sulfonate has a hydrophilicity corresponding to the degree of water absorption at room temperature, which absorbs 2% by weight of water, to the complete dissolution in water.
Especially for use as a separation membrane, 2-80% by weight at room temperature
It is desirable to absorb water, preferably 5 to 40% by weight of water.

Also, the logarithmic viscosity, which is an index of the degree of condensation or molecular weight of the polymer, is at least 0.
It is preferably 2 or more (0.5 g polymer / 100 mN-methylpyrrolidone, 30 ° C).

The sulfonated polyaryl ether-based polymers of the present invention not only feature hydrophilicity, but retain considerable strength even when they contain a significant amount of water (eg, 20 wt% water). Therefore, a film formed from this sulfonated polymer is useful as a material for partition membranes in electrodialyzers, membranes for separating solutions or suspensions, reverse osmosis membranes, ultrafiltration membranes, and other separation membranes. .

(e) Action The sulfonation of the polyarylether polymer comprising the repeating unit A or the repeating unit B can be achieved by dissolving the polymer in concentrated sulfuric acid and stirring. Repeating unit A is immediately sulfonated by sulfonation with concentrated sulfuric acid, while repeating unit B is not. It is considered that this is due to the unique structure of the repeating unit A.

Then, the solution of the sulfonated polyaryl ether polymer obtained by the sulfonation is subjected to ordinary film forming treatment such as casting to form a film. This membrane has a considerable membrane strength even in the water-containing state, and it is considered that this is because the unique structure of the repeating unit A imparts flexibility to the polymer.

(f) Examples Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

Example 1 a. Formula of polyaryl ether sulfone 80 mol% of the repeating unit A represented by A linear polyarylethersulfone consisting of 20 mol% of the repeating unit B shown in was prepared as follows.

4,4'-Dihydroxydiphenyl sulfone 25.0 g
(0.1 mol) was placed in a flask equipped with a stirrer, a nitrogen gas introduction tube, a drainage tube and a thermometer, and further sulfolane 20 was added.
0 m and xylene 100 m were added. This was refluxed at a temperature of 155 ° C. for 1 hour while stirring with heating by a mantle heater, and 5.3 m of water was extracted at this time.

Then, the temperature was lowered to 110 ° C., and 28.8 g (0.1 mol) of 4,4′-dichlorodiphenyl sulfone, 10.3 g (0.08 mol) of p-chlorophenol and 27.6 g (0.2 mol) of potassium carbonate. Mol) was added to start the polymerization reaction. After refluxing for 1 hour at a temperature of 162 ° C., the temperature was raised to 200 ° C. while draining water for 2.5 hours, and the temperature was raised to 2 ° C.
Reflux was continued at 00-215 ° C for 4 hours. The amount of water withdrawn during this reaction was 2.0 m.

After a part of the reaction solution was applied to a glass plate and it was confirmed that a film could be formed when immersed in water, the temperature was lowered to 100 ° C. and 220 m of dichloromethane was added. The reaction mixture thus obtained was poured into pure water to coagulate the polyarylethersulfone, washed with pure water and then with acetone, and then dried at a temperature of 80 ° C. for 6.5 hours.

The linear polyaryl ether sulfone thus obtained was a pale yellow granular material and had an inherent viscosity of 0.90.
(0.5 g polymer / 100 m.P-chlorophenol, 47 ° C.).

B. Production of Sulfonated Polyaryl Ether Sulfone 10 g of the polymer obtained as described above was added to 80 m of 97% by weight concentrated sulfuric acid and dissolved, and the mixture was stirred and reacted at room temperature for 4 hours to obtain a blackish brown viscous reaction liquid. It was This was put into an ice bath to coagulate the sulfonated polymer. After washing with water, 800m of 0.5N sodium hydroxide solution
Left inside overnight. Then, this polymer was washed until the washing liquid became neutral, and then vacuum dried at a temperature of 60 ° C. for 5 hours.

The pale yellow granular sulfonated polyarylethersulfone thus obtained had an inherent viscosity of 1.03 (0.
5 g polymer / 100 mN-methylpyrrolidone, 3
0 ° C.), and the ion exchange capacity was 1.0 meq / g. The water content at room temperature was 20% by weight.

When the polymer thus obtained was analyzed by NMR as a dimethyl sulfoxide solution, the above-mentioned a. Approximately 100 mol% of the repeating unit A shown at the beginning of --- SO ₃ N
It was found to have a.

C. Production of Sulfonated Polyaryl Ether Sulfone Film The sulfonated polyaryl ether sulfone film is
Obtained by dissolving 5 g of the above sulfonated polymer in 25 g of 2-methoxyethanol, casting this solution on a glass plate, evaporating most of the solvent at room temperature, and then leaving it in a dryer at 60 ° C. for 3 hours. It was

The resulting film had a thickness of 0.2 mm. Burst pressure was 4 according to US Pat. No. 3,709,841.
It was kg / cm ² (deflection at rupture 6.5 mm). The tensile strength upon drying was 5.6 kg / mm ² , and the tensile strength upon absorbing 20% by weight of water was 4.1 kg / mm ² .

Also, a film having a thickness of 20 μm was obtained in the same manner as above, and using this, a concentration of 5 g / was obtained by reverse osmosis under 80 kg / cm ^2.
When treated with an aqueous solution of NaCl, the salt removal rate was 99.5%
And the flow rate was 30 / m ² days.

Comparative Example 1 Formula 80 mol% of the repeating unit represented by the formula Of Example 1 except that a polyaryl ether sulfone having 20 mol% of the repeating unit represented by The sulfonation was carried out under the same conditions as in.

The sulfonated polyarylethersulfone thus obtained had an inherent viscosity of 1.10 (0.5 g polymer / 100 mN-methylpyrrolidone, 30 ° C.) and an ion exchange capacity of 1.0 meq / g. there were. The water content at room temperature was 20% by weight.

When the polymer thus obtained was analyzed by NMR as a dimethyl sulfoxide solution, the repeating unit Almost 100 mol% of it was found to have a -SO ₃ Na.

In addition, this polymer was used in the same manner as in Example 1. It was made into a film in the same manner as. The resulting film had a thickness of 0.2 mm. The burst pressure according to US Pat. No. 3,709,841 was 3.5 kg / cm ² (deflection at burst 6.0 mm). The dry tensile strength was 4.8 kg / mm ² , and the wet tensile strength was 2.7 kg / mm ² .

Example 2 The sulfonation was carried out in the same manner as in Example 1 except that the sulfonation time was changed to 1 hour.

NMR analysis of this polymer as a dimethyl sulfoxide solution
Analysis revealed that almost 98 mol% of the repeating unit A was
It was found to have SO ₃ Na.

Comparative Example 2 Sulfonation was carried out in the same manner as Comparative Example 1 except that the sulfonation time was changed to 1 hour.

NMR analysis of this polymer as a dimethyl sulfoxide solution
When analyzed by Approximately 83 mol% of it was found to have a -SO ₃ Na.

Example 3 a. Formula of polyaryl ether sulfone The linear polyaryl ether sulfone consisting of the repeating unit A shown in FIG. It was manufactured in the same manner as. However, as the monomer component, 4,4'-dihydroxydiphenyl sulfone 25.0 g (0.1 mol),
28.7 g of 4'-dichlorodiphenyl sulfone (0.1
12.5 g (0.1 mol) of p-chlorophenol.

The linear polyaryl ether sulfone thus obtained was a pale yellow granular material and had an inherent viscosity of 1.40.
(0.5 g polymer / 100 m.P-chlorophenol, 47 ° C.).

B. Preparation of Sulfonated Polyaryl Ether Sulfone The polymer obtained as described above was treated with 97% by weight concentrated sulfuric acid in Example 1B. Sulfonated under the same conditions as above. However, the reaction time was 1 hour.

The pale yellow granular sulfonated polyarylethersulfone thus obtained had an inherent viscosity of 2.80 (0.
5 g polymer / 100 mN-methylpyrrolidone, 3
0 ° C.), and the ion exchange capacity was 1.5 meq.
The water content at room temperature was 25% by weight.

When the polymer thus obtained was analyzed by NMR as a dimethylsulfoxide solution, it was found that 99 mol% of the repeating unit A had —SO ₃ Na.

C. Preparation of Sulfonated Polyaryl Ether Sulfone Film A sulfonated polyaryl ether sulfone film was prepared according to Created in the same manner as.

The resulting film had a thickness of 0.2 mm. The burst pressure according to US Pat. No. 3,709,841 was 4.3 kg / cm ² (deflection at burst 6.6 mm).
The tensile strength when dry was 5.7 kg / mm ² and the tensile strength when wet was 4.3 kg / mm ² .

Also, a 20 μm film was obtained in the same manner as above, and using this, reverse osmosis was carried out under 80 kg / cm ² to obtain a concentration of 5 g / NaC.
When the aqueous solution was treated, the salt removal rate was 99.4%, and the flow rate was 31 / m ² days.

Example 4 a. Formula of polyaryl ether sulfone 20 mol% of the repeating unit A _{1 represented} by the formula: 40 mole% of the repeating unit A _{2 represented by} 20 mol% of the repeating unit A _{3 represented by} A linear polyaryl ether sulfone consisting of repeating unit B of 20 mol% It was manufactured in the same manner as. However, as a monomer component, 25.0 g (0.1 mol) of 4.4'-dihydroxydiphenyl sulfone and 28.8 g of 4,4'-dichlorodiphenyl sulfone
(0.1 mol), p-chlorophenol 20.6 g
(0.16 mol), potassium carbonate is 41.4 g
(0.3 mol) was used.

After adding p-chlorophenol to this and reacting for 1 hour, the temperature was lowered to 110 ° C. and the reaction was carried out by adding 4,4′dichlorodiphenyl sulfone.

The linear polyaryl ether sulfone thus obtained was a pale yellow granular material and had an inherent viscosity of 0.8.
(0.5 g polymer / 100 m · p-chlorophenol, 47 ° C.).

B. Preparation of Sulfonated Polyaryl Ether Sulfone The polymer obtained as described above was treated with 97% by weight concentrated sulfuric acid in Example 1B. Sulfonated under the same conditions as above. However, the reaction time was 1 hour.

The pale yellow granular sulfonated polyarylethersulfone thus obtained has an inherent viscosity of 1.6 (0.5
g polymer / 100 mN-methylpyrrolidone, 30
C.) and the ion exchange capacity was 1.2 meq / g.
The water content at room temperature was 23% by weight.

When this sulfonated polymer was analyzed by NMR as a dimethyl sulfoxide solution, Approximately 100 mol% of the repeating units A ₁ , A ₂ and A ₃ shown at the beginning of
It was found to have SO ₃ Na.

C. Preparation of Sulfonated Polyaryl Ether Sulfone Film A sulfonated polyaryl ether sulfone film was prepared according to Created in the same manner as.

The resulting film had a thickness of 0.2 mm. Burst pressure was 4 according to US Pat. No. 3,709,841.
It was kg / cm ² (deflection at rupture 6.5 mm). The tensile strength when dry 5.3 kg / mm ^2, the tensile strength of the wet was 4.0 kg / mm ^2.

Also, a film having a thickness of 20 μm was obtained in the same manner as above, and using this, a concentration of 5 g / was obtained by reverse osmosis under 80 kg / cm ^2.
When treated with NaCl aqueous solution, the salt removal rate was 99.4%
And the flow rate was 33 / m ² days.

Example 5 a. Formula of polyaryl ether ketone 80 mol% of the repeating unit A represented by A linear polyaryletherketone consisting of 20 mol% of the repeating unit B It was manufactured in the same manner as. However, as the monomer component, 4,4'-dihydroxybenzophenone 22.6 g (0.1 mol),
26.3 g (0.1 mol) of 4'-dichlorobenzophenone and 10.3 g (0.08 mol) of o-chlorophenol were used.

The linear polyaryl ether ketone thus obtained is a pale yellow granular material, and its logarithmic viscosity is 0.9 (0.
5g polymer / 100m p-chlorophenol, 4
7 ° C).

B. Preparation of Sulfonated Polyaryl Ether Ketone The polymer obtained as described above was subjected to the procedure of Example 1 b. Sulfonated under the same conditions as above. However, the reaction time was 1 hour.

The pale yellow granular sulfonated polyaryl ether ketone thus obtained has an inherent viscosity of 1.01 (0.5
g polymer / 100 mN-methylpyrrolidone, 30
C.) and the ion exchange capacity was 1.1 meq / g.
The water content at room temperature was 20% by weight.

When this sulfonated polymer was analyzed by NMR as a dimethyl sulfoxide solution, Almost 100 mol% of repeat units A shown at the beginning of it was found to have a -SO ₃ Na.

C. Preparation of Sulfonated Polyaryl Ether Ketone Film A sulfonated polyaryl ether ketone film was prepared as in Example 1. Created in the same manner as.

The resulting film had a thickness of 0.2 mm. The burst pressure according to US Pat. No. 3,709,841 was 4.2 kg / cm ² (deflection at burst 6.3 mm).
The dry tensile strength was 5.3 kg / mm ² , and the wet tensile strength was 3.9 kg / mm ² .

Also, a film having a thickness of 20 μm was obtained in the same manner as above, and using this, a concentration of 5 g / was obtained by reverse osmosis under 80 kg / cm ^2.
When treated with an aqueous solution of NaCl, the salt removal rate was 99.6%
And the flow rate was 28 / m ² days.

Comparative Example 3 Formula 80 mol% of the repeating unit represented by the formula Of Example 5, except that a polyaryl ether ketone consisting of 20 mol% of the repeating unit represented by The sulfonation was carried out under the same conditions as in.

The sulfonated polyaryl ether ketone thus obtained had an inherent viscosity of 0.6 (0.5 g polymer / 10
0 mN-methylpyrrolidone, 30 ° C.), and the ion exchange capacity was 0.8 meq / g. The water content at room temperature was 20% by weight.

This sulfonated polymer was dissolved in dimethylsulfoxide and analyzed by NMR. 85 mol% of it was found to have a -SO ₃ Na.

Further, this polymer was prepared by It was made into a film in the same manner as. The resulting film had a thickness of 0.2 mm. The burst pressure according to US Pat. No. 3,709,841 was 3.8 kg / cm ² (deflection at burst 5.0 mm). The tensile strength when dry 4.9 kg / mm ^2, the tensile strength of the wet was 3.0 kg / mm ^2.

(g) Effect of the Invention In the production of the sulfonated polyarylether polymer of the present invention, concentrated sulfuric acid is gently used as a sulfonating agent without using a highly oxidizing agent such as sulfuric anhydride or chlorosulfonic acid. Since sulfonation can be performed and the reaction time at that time is short, it is industrially advantageous in terms of prevention of danger during polymerization and productivity.

When the polyarylether-based polymer contains the repeating unit A or the repeating unit B, only the repeating unit A is sulfonated by sulfonation, and the repeating unit B is not substantially sulfonated. A and repeating unit B
The degree of sulfonation can be arbitrarily adjusted by appropriately selecting the ratio.

The sulfonated polyaryl ether-based polymer of the present invention is, compared with conventionally known sulfonated polyaryl ether sulfone and sulfonated polyaryl ether ketone,
Since it has excellent membrane characteristics such as high membrane strength in a water-containing state and long membrane life, it is extremely preferable as a material for a separation membrane that handles an aqueous solution.

In particular, when n different repeating units A are contained in the same polymer, flexibility is imparted as a result,
Membrane characteristics are further improved in applications of separation membranes.

Claims (3)

[Claims] 1. A formula (In the formula, n is an integer of 1 or more, and X ₁ and X ₂ are CO or SO.
Represents ₂ . ) The repeating unit A represented by
And expression A sulfonated polymer having a repeating unit B represented by the following formula, wherein the ratio of the repeating unit A to the repeating unit B when the repeating unit B is contained is such that the repeating unit A is 1 to 99 mol% and the repeating unit B is 99-1 mol% and the formula in repeating unit A The sulfonation degree is such that the sulfonated product has a hydrophilicity corresponding to the degree of water absorption of 2 wt% of water absorbed at room temperature to complete dissolution in water. Furthermore, the logarithmic viscosity, which is an index of the degree of condensation or the molecular weight of the polymer, is at least 0.2 (0.5 g polymer / 1
A sulfonated polyarylether polymer characterized in that it is 00 ml N-methylpyrrolidone, 30 ° C.). 2. The sulfonated polyaryl ether polymer according to claim 1, wherein n different repeating units A are contained in the same polymer molecule. 3. A formula (In the formula, n is an integer of 1 or more, and X ₁ and X ₂ are CO or SO.
Represents ₂ . ) The repeating unit A represented by
And expression A method for producing a sulfonated polyaryl ether-based polymer, which comprises sulfonation of a polymer having the repeating unit B shown in 1) with concentrated sulfuric acid.