JP2013079367A - Aromatic sulfonate ester derivative, polymer containing sulfonate ester group, polyelectrolyte material using the same, polyelectrolyte molding using the same, electrolytic film with catalyst layer and polymer electrolyte fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyelectrolyte material which has an excellent proton conductivity under low humidity, is excellent in mechanical strength and chemical stability, and, when made into a polymer electrolyte fuel cell, achieves high output and excellent physical durability; and to provide a polyelectrolyte molding using the same, an electrolytic film with a catalyst layer and a polymer electrolyte fuel cell.SOLUTION: A polymer containing a sulfonate ester group is prepared by polymerization using an aromatic sulfonate ester derivative represented by a specific structure. For example, a constituent unit represented by formula (P1) is contained. (In the formula (P1), Rs represent each independently a 1-20C hydrocarbon group for each sulfonate ester group, and may include a hetero atom).

Description

  The present invention relates to an aromatic sulfonic acid ester derivative, a sulfonic acid ester group-containing polymer using the same, and a sulfonic acid group-containing polymer obtained by deesterifying the aromatic sulfonic acid ester derivative, and in particular, excellent under low humidification conditions. A polymer electrolyte material having excellent practicality capable of achieving excellent mechanical strength, chemical stability and physical durability, and a polymer electrolyte molded body using the same. The present invention relates to an electrolyte membrane with a catalyst layer and a polymer electrolyte fuel cell.

  BACKGROUND ART A fuel cell is a kind of power generation device that extracts electrical energy by electrochemically oxidizing a fuel such as hydrogen or methanol, and has recently attracted attention as a clean energy supply source. In particular, the polymer electrolyte fuel cell has a standard operating temperature as low as around 100 ° C. and a high energy density, so that it is a relatively small-scale distributed power generation facility, a mobile power generator such as an automobile or a ship. As a wide range of applications are expected. It is also attracting attention as a power source for small mobile devices and portable devices, and is expected to be installed in mobile phones and personal computers in place of secondary batteries such as nickel metal hydride batteries and lithium ion batteries.

  In a fuel cell, an anode electrode and a cathode electrode in which a reaction responsible for power generation occurs, and a polymer electrolyte membrane serving as a proton conductor between the anode and the cathode are sometimes referred to as a membrane electrode assembly (hereinafter, abbreviated as MEA). ) And a cell in which this MEA is sandwiched between separators is configured as a unit. The polymer electrolyte membrane is mainly composed of a polymer electrolyte material. The polymer electrolyte material is also used as a binder for the electrode catalyst layer.

  The required characteristics of the polymer electrolyte membrane include firstly high proton conductivity, and it is particularly necessary to have high proton conductivity even under high temperature and low humidification conditions. In addition, since the polymer electrolyte membrane also functions as a barrier that prevents direct reaction between fuel and oxygen, low permeability of the fuel is required. Other examples include chemical stability to withstand a strong oxidizing atmosphere during fuel cell operation, mechanical strength and physical durability to withstand repeated thinning and swelling and drying.

Since proton conductivity depends on the water content of the membrane, it was necessary to maintain high humidity conditions in order to achieve high power generation performance as a fuel cell. Along with this, there was a problem that the load on the humidifier increased, and under freezing point, water in the conductive membrane involved in proton conduction was frozen, so that proton conductivity was greatly reduced and power generation could not be performed. .

Conventionally, Nafion (registered trademark) (manufactured by DuPont), which is a perfluorosulfonic acid polymer, has been widely used for polymer electrolyte membranes. However, Nafion (registered trademark) is very expensive because it is manufactured through multi-step synthesis, and in addition, there is a problem that fuel crossover is large. In addition, problems such as loss of mechanical strength and physical durability of the membrane due to swelling and drying, problems of low softening point and inability to use at high temperatures, problems of disposal treatment after use and difficulty in recycling materials are pointed out. It has been.

  In order to overcome such drawbacks, development of a hydrocarbon polymer electrolyte membrane that can replace Nafion (registered trademark) at low cost and excellent in membrane characteristics has recently been activated.

  Among them, some attempts have been made focusing on aromatic sulfonic acid group-containing polymers that can be produced at low cost and on an industrial scale.

  Non-patent documents 1 to 3 describe a polyethersulfone-based sulfonic acid group-containing polymer.

  Patent Document 1 proposes a sulfonic acid ester group-containing aromatic polymer and a sulfonic acid group-containing aromatic polymer obtained by deesterification thereof.

JP-A-2005-197235

Applied Materials and Interfaces, 1, 1279, 2009. Journal of Polymer Science: Part A: Polymer Chemistry, 41, 2264, 2003. Journal of Polymer Science: Part A: Polymer Chemistry, 46, 7332, 2008.

  However, the present inventors have found that the prior art has the following problems. The polyethersulfone-based sulfonic acid group-containing polymer described in Non-Patent Document 1 is a polymer obtained by sulfonating a hydrophobic polymer precursor using chlorosulfonic acid in a chlorinated solvent (hereinafter referred to as post-sulfonation). The post-sulfonation was difficult to control due to the precipitation of the polymer as the sulfonation progressed, and in addition to the polymer reaction, and it was difficult to introduce a highly sulfonic acid group, resulting in poor power generation performance. Furthermore, due to the action of a highly active sulfonating agent, deterioration of the polymer and a decrease in mechanical properties were considered as further problems.

  As a method for introducing a sulfonic acid group into a polymer without using a post-sulfonation reaction, Non-Patent Document 2 discusses a method of polymerizing and polymerizing using a monomer having a sulfonic acid group previously introduced. However, with the introduction of the sulfonic acid group, a polymer is precipitated during the reaction, and it is difficult to obtain a polymer having both a high sulfonic acid group density and a high molecular weight, which is inferior in power generation performance and physical durability. Furthermore, with regard to the sulfonic acid group-containing block polymer described in Non-Patent Document 3, the solubility of the highly sulfonic acid group-introduced segment in the organic solvent was reduced with chain length elongation, and it was considered difficult to increase the molecular weight. .

In contrast, the polyether nitrile polymer containing a sulfonate group described in Patent Document 1 introduces a sulfonate group as a sulfonate group precursor, thereby making the sulfonate group insensitive to the coupling reaction. In addition, the polymer can be polymerized by improving the solubility of the raw material and the produced polymer in an organic solvent. However, since the polymer uses an amorphous polymer having a high glass transition temperature as a basic skeleton, the polymer becomes brittle and has poor physical durability. In addition, hot water resistance and physical durability degradation due to the inclusion of many sulfonic acid groups with high water absorption were further cited as problems. Thus, the polymer electrolyte material in the prior art is insufficient as a means for improving economy, workability, proton conductivity, mechanical strength, chemical stability, and physical durability, and is industrially useful. It could not be a polymer electrolyte membrane.

In view of the background of such prior art, the present invention has excellent proton conductivity even under low humidification conditions, and is excellent in mechanical strength and fuel shut-off property. We do not provide sulfonate group-containing polymers that provide polyelectrolyte materials that can achieve output, high energy density, and long-term durability, and sulfonate group-containing polymers obtained by deesterifying them, and aromatic sulfonate ester derivatives. It is what.

  The present invention employs the following means in order to solve this problem without using a post sulfonation reaction. That is, the aromatic sulfonate derivative of the present invention is represented by the following general formula (M1).

(In formula (M1), Z represents an electron withdrawing group. R represents a hydrocarbon group having 1 to 20 carbon atoms independently for each sulfonate group, and may contain a hetero atom. X ¹ and X ² each represent a halogen atom.)
The sulfonic acid ester group-containing polymer of the present invention is characterized by being polymerized using such an aromatic sulfonic acid ester derivative and containing a structural unit represented by the following general formula (P1). It is.

(In the formula (P1), each R independently represents a hydrocarbon group having 1 to 20 carbon atoms for each sulfonate group and may contain a hetero atom.) Furthermore, the polymer electrolyte material of the present invention The polymer electrolyte molded body using the same, the electrolyte membrane with a catalyst layer, and the solid polymer fuel cell are composed of a sulfonic acid group-containing polymer obtained by deesterifying the sulfonic acid ester group-containing polymer. It is characterized by.

According to the polymer electrolyte material composed of the sulfonic acid ester group-containing polymer polymerized using the aromatic sulfonic acid ester derivative of the present invention, and the sulfonic acid group-containing polymer obtained by deesterification of the polymer, under low humidification conditions, Excellent proton conductivity, high mechanical strength, high chemical stability, and high output performance and excellent physical durability when used as a polymer electrolyte fuel cell. An electrolyte molded body, an electrolyte membrane with a catalyst layer, and a polymer electrolyte fuel cell can be provided.

  Hereinafter, the present invention will be described in detail.

As a result of intensive studies aimed at overcoming the above problems, the present invention provides an aromatic sulfonate ester derivative, a sulfonate group-containing polymer polymerized using the same, and a sulfonate group-containing polymer having a specific structure. , When induced to a sulfonic acid group via deesterification, as a polymer electrolyte material, particularly an electrolyte membrane for a fuel cell, proton conductivity including low humidification conditions and power generation characteristics, processability such as film forming properties, It has been found that it is possible to express excellent performance in chemical stability such as oxidation resistance, radical resistance, hydrolysis resistance, etc., mechanical strength of the membrane, physical durability such as hot water resistance, and to solve such problems all at once. Is.

That is, the aromatic sulfonate derivative of the present invention is represented by the following general formula (M1).

(In formula (M1), Z represents an electron-withdrawing group, R represents a C1-C20 hydrocarbon group each independently for every sulfonate group, and may contain the hetero atom. X ¹ and X ² each represent a halogen atom.)
Here, specific examples of X ¹ and X ² include fluorine, chlorine, bromine, and iodine. Among them, fluorine and chlorine are more preferable, and fluorine is most preferable in terms of reactivity. Specific examples of the electron withdrawing group Z include —CO—, —CONH—, — (CF ₂ ) _n — (n is an integer of 1 to 10), —C (CF ₃ ) ₂ —, —COO. —, —SO ₂ —, —SO—, —PO (R ¹ ) — (wherein R ¹ is an arbitrary organic group), and the like, among others, —CO—, — (CF ₂ ) _n — (n is 1 10 _{integer), - C (CF 3)} 2 -, - SO 2 -, - PO (R 1) - (R 1 is any organic group) it is preferable, from the viewpoint of chemical stability and cost, - CO -, - SO ₂ - is more preferable, from the viewpoint of physical durability -CO- are most preferred.

The aromatic sulfonic acid ester derivative of the present invention is excellent in chemical stability due to the effect of the electron-withdrawing group Z, and has improved solubility in organic solvents and good polymerization when used as a sulfonic acid ester group-containing polymer. When an sulfonic acid group-containing polymer is made possible by deesterification, an electrolyte membrane having high proton conductivity and excellent durability can be obtained. Here, the organic solvent is not particularly limited as long as it dissolves the polymer electrolyte material and can be removed thereafter. For example, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, sulfolane, 1 , 3-dimethyl-2-imidazolidinone, aprotic polar solvents such as hexamethylphosphonetriamide, ester solvents such as γ-butyrolactone and butyl acetate, carbonate solvents such as ethylene carbonate and propylene carbonate, ethylene glycol monomethyl ether , Ethylene glycol monoethyl ether, propylene glycol monomethyl ether, alkylene glycol monoalkyl ethers such as propylene glycol monoethyl ether, alcohol solvents such as isopropanol, water and Mixtures et is preferably used, polymerizable, aprotic polar solvents in terms of solubility is most preferred.

R may be different for each sulfonate group, and represents a hydrocarbon group having 1 to 20 carbon atoms and a hydrocarbon group containing a hetero atom. Preferably, it is a C4-C20 hydrocarbon group (which may contain a hetero atom), specifically, a tert-butyl group, an iso-butyl group, an n-butyl group, a sec-butyl group, Neopentyl group, cyclopentyl group, hexyl group, cyclohexyl group, cyclopentylmethyl group, cyclohexylmethyl group, adamantyl group, adamantylmethyl group, 2-ethylhexyl group, bicyclo [2.2.1] heptyl group, bicyclo [2.2.1 ] Straight chain hydrocarbon group such as heptylmethyl group, tetrahydrofurfuryl group, 2-methylbutyl group, 3,3-dimethyl-2,4-dioxolanemethyl group, branched hydrocarbon group, alicyclic hydrocarbon group In addition, hydrocarbon arylene groups such as phenyl, naphthyl, biphenyl, and fluorenyl, pyridyl, quinoxalyl, and thiof Such heteroarylene groups, such as alkenyl groups. Among these, n-butyl group, iso-butyl group, neopentyl group, tetrahydrofurfuryl group, cyclopentylmethyl group, cyclopentyl group, cyclohexyl group, cyclohexylmethyl group, adamantylmethyl group, bicyclo [2,2,1] heptylmethyl Group, phenyl group, naphthyl group, and biphenyl group are preferable, and neopentyl group and phenyl group are more preferable, and neopentyl group is most preferable in view of ease of synthesis and polymerization.

  However, the hydrocarbon-based arylene group and heteroarylene group may have an arbitrary substituent. Substituents include methyl group, ethyl group, tert-butyl group, iso-butyl group, n-butyl group, sec-butyl group, neopentyl group, cyclopentyl group, hexyl group, cyclohexyl group, cyclopentylmethyl group, cyclohexylmethyl group , Adamantyl group, adamantylmethyl group, 2-ethylhexyl group, bicyclo [2.2.1] heptyl group, bicyclo [2.2.1] heptylmethyl group, tetrahydrofurfuryl group, 2-methylbutyl group, 3,3- In addition to linear hydrocarbon groups such as dimethyl-2,4-dioxolane methyl group, branched hydrocarbon groups and alicyclic hydrocarbon groups, hetero atoms such as oxygen atom derivatives, sulfur atom derivatives and nitrogen atom derivatives thereof Derivatives, and further hetero groups such as nitro groups. Specific examples of the derivative include a methoxy group, an ethoxy group, a thiomethoxy group, a thioethoxy group, and a dimethylamino group, but are not limited to these examples.

  R in the general formula (M1) is derived from an alcohol used when the sulfonate derivative is synthesized. In particular, when a primary alcohol is used, the β-carbon of the primary alcohol is preferably a tertiary or quaternary carbon atom, and more preferably a quaternary carbon atom. In this case, the carbon atom has excellent stability in the polymerization process, and does not inhibit the polymerization or induce a crosslinking reaction by a sulfonic acid generated by deesterification. Moreover, when synthesizing the sulfonic acid ester derivative having the arylene group as R, an aromatic alcohol corresponding to the arylene group may be used, and the sulfonic acid ester derivative synthesized by the step is also a polymerization step. Has excellent stability.

  As the aromatic sulfonic acid ester derivative of the present invention, those represented by the following general formula (M2) are more preferable from the viewpoint of ease of synthesis and physical durability.

(In formula (M2), each R independently represents a hydrocarbon group having 1 to 20 carbon atoms for each sulfonate group, and may contain a hetero atom.)
Next, the sulfonate group-containing polymer of the present invention will be described.

  The sulfonic acid ester group-containing polymer of the present invention is characterized by being polymerized using the aromatic sulfonic acid ester derivative represented by the general formula (M1). Moreover, although it became clear by superposing | polymerizing using the aromatic sulfonic acid ester derivative represented by the said general formula (M1), it has not only that but a specific structure, It is characterized by the above-mentioned.

  Specific examples thereof include sulfonic acid ester group-containing aromatic polyether ketones, sulfonic acid ester group-containing aromatic polyether sulfones, sulfonic acid ester group-containing aromatic polyether phosphine oxides, and sulfonic acid ester group-containing aromatics. Aromatic polymers such as polysulfide ketones, sulfonic acid ester group-containing aromatic polysulfide sulfones, sulfonic acid ester group-containing aromatic polysulfide phosphine oxides, and sulfonic acid ester group-containing polyarylenes can be exemplified.

  Among them, from the viewpoint of cost, aromatic polyether ketones containing sulfonic acid ester groups, aromatic polyether sulfones containing sulfonic acid ester groups, aromatic polyether phosphine oxides containing sulfonic acid ester groups, and containing sulfonic acid ester groups Polyarylenes are more preferred, sulfonic acid ester group-containing aromatic polyether ketones, sulfonic acid ester group-containing aromatic polyether sulfones, most preferably sulfonic acid ester group-containing aromatic polyether ketones It is.

  These sulfonic acid ester group-containing aromatic polyethers are synthesized by an aromatic nucleophilic substitution reaction between the aromatic sulfonic acid ester derivative (dihalide compound) represented by the general formula (M1) and an arbitrary dihydric phenol compound. It is possible. The divalent phenol compound is not particularly limited, and can be appropriately selected in consideration of chemical stability, physical durability, cost, and the like. In addition, these dihydric phenol compounds into which a sulfonic acid ester group is introduced can be used as a monomer as long as they do not adversely affect the effects of the present invention, but they have a sulfonic acid ester group in terms of reactivity. More preferably not. Specific examples of suitable divalent phenol compounds used in the present invention include divalent phenol compounds represented by the following general formulas (Y-1) to (Y-30). Divalent thiol compounds that are heteroatom derivatives of these divalent phenol compounds are also suitable examples. Among divalent phenol compounds having a high electron density and high polymerization reactivity, divalent phenol compounds represented by general formulas (Y-1) to (Y-5) are preferred, and more preferably (Y-1) to It is a divalent phenol compound represented by (Y-3), and a divalent phenol compound represented by (Y-1) is more preferable.

On the other hand, the following formulas (Y-10) to (Y-11) and (Y-13) to (Y-15) are listed as divalent phenol compounds having an electron-withdrawing group and excellent in chemical stability. It is done. Of these, divalent phenol compounds represented by (Y-10), (Y-11), (Y-13), (Y-14), and (Y-15) are preferable from the viewpoint of ease of synthesis. In terms of crystallinity and dimensional stability, divalent phenol compounds represented by (Y-10), (Y-14), and (Y-15) are more preferred, and 2 represented by (Y-14). Most preferred are polyhydric phenol compounds.

  Among the dihydric phenol compounds represented by the following general formulas (Y-1) to (Y-30), the dihydric phenol compound represented by the following general formula (Y-14) has chemical stability and physical properties. Most preferable in terms of stability.

(The divalent phenol compound represented by the general formulas (Y-1) to (Y-5) may be optionally substituted, but does not include a sulfonic acid ester group.

(The divalent phenol compounds represented by the general formulas (Y-6) to (Y-9) may be optionally substituted, but n represents an integer of 1 or more.)

(The dihydric phenol compounds represented by the general formulas (Y-10) to (Y-19) may be optionally substituted, but n and m are integers of 1 or more, and Rp is an arbitrary organic group. Represents.)

(The dihydric phenol compounds represented by the general formulas (Y-20) to (Y-30) may be optionally substituted.)

For example, a structural unit obtained by an aromatic nucleophilic substitution reaction of an aromatic sulfonic acid ester derivative (dihalide compound) represented by the general formula (M1) and a divalent phenol compound represented by the general formula (Y-14) Is represented by the following general formula (P1), and is a particularly preferred specific example as a constituent unit of the sulfonate group-containing polymer of the present invention.

(In formula (P1), each R independently represents a hydrocarbon group having 1 to 20 carbon atoms for each sulfonate group and may contain a hetero atom.)
One of the preferable embodiments of the sulfonate group-containing polymer in the present invention is a sulfonate group-containing polymer having a structural unit represented by the general formula (P1). When the structural unit represented by the general formula (P1) is not included, the solubility in an organic solvent is lowered, polymerization and film formation become difficult, and the effects of the present invention may not be sufficiently obtained, which is not preferable.

  Furthermore, the content of the structural unit represented by the general formula (P1) in the sulfonate group-containing polymer of the present invention is preferably 20% by weight or more. When the content of the structural unit represented by (P1) is less than 20% by weight, the hot water resistance, physical durability, and proton conductivity that are the effects of the present invention may not be compatible, which is not preferable. Examples of the protective group used in the sulfonate group-containing polymer of the present invention include a protective group generally used in organic synthesis. The protective group is temporarily removed on the assumption that it is removed at a later stage. It is a substituent that is introduced into, which protects a highly reactive functional group and renders it inert to the subsequent reaction, and can be deprotected after the reaction to return to the original functional group. is there. That is, it is a pair with a functional group to be protected. For example, a t-butyl group may be used as a protective group for a hydroxyl group, but when the same t-butyl group is introduced into an alkylene chain, It is not called a protecting group. The reaction for introducing a protecting group is called protection (reaction), and the reaction for removal is called deprotection (reaction).

  Such protection reactions include, for example, Theodora W. G reene, “Protective Groups in Organic Synthesis”, US, John Willy and Sands (John Wiley & Sons, Inc), 198 1, are described in detail, and these can be preferably used. It can be appropriately selected in consideration of the reactivity and yield of the protection reaction and deprotection reaction, the stability of the protecting group-containing state, the production cost, and the like. In addition, the stage for introducing a protecting group in the polymerization reaction may be selected from the monomer stage, the oligomer stage, or the polymer stage, and can be appropriately selected.

  Specific examples of the protection reaction include protecting / deprotecting the ketone moiety with an acetal or ketal moiety, and protecting / deprotecting the ketone moiety with a heteroatom analog of the acetal or ketal moiety, such as thioacetal or thioketal. The method of doing is mentioned. These methods are described in Chapter 4 of “Protective Groups in Organic Synthesis” (P rot e c t i v e G r o u ps i n O r g a n iC Snt h e s i s). However, it is not limited to these and can be preferably used. In terms of improving solubility in general solvents and reducing crystallinity, an aliphatic group, particularly an aliphatic group containing a cyclic moiety, is preferably used as a protective group in terms of large steric hindrance, and protects the ketone moiety. As the group, an acetal group and a ketal group are particularly preferably used. In the present invention, in order to obtain the sulfonic acid group-containing polymer represented by the general formula (P1), a protective group is introduced into the dihydric phenol compound, and after the polymerization or molding, the deprotection is performed. It is also preferable to convert to a structure represented by Preferred specific examples of the dihydric phenol compound having a protecting group include compounds represented by the following general formulas (r1) to (r10), and these dihydric phenol compounds from the viewpoint of reactivity and chemical stability. Derivatives can be mentioned.

Among these dihydric phenol compounds, the compounds represented by the general formulas (r4) to (r10) are more preferable from the viewpoint of stability, and more preferably the compounds represented by the general formulas (r4), (r5), and (r9). The compound represented by the general formula (r4) is most preferred.

The sulfonate group-containing polymer of the present invention has at least a segment (A1) having a structural unit represented by the general formula (P1) and a segment (A2) having a structural unit not containing an ionic group. The copolymerization mode is preferably block copolymerization.

  In the present invention, the block copolymer represents a mode in which two or more different segments are copolymerized, and the segment is a partial structure in the block copolymer, and includes one type of repeating unit or a plurality of types of repeating units. It consists of a combination of repeating units and represents a molecular weight of 2000 or more. The sulfonate group-containing polymer comprising the block copolymer of the present invention has a segment containing a sulfonate group represented by the general formula (P1) and a segment not containing an ionic group. The ionic group in includes a substituent that can be derived into an ionic group by a deesterification treatment such as hydrolysis, for example, the sulfonate group of the present invention. In addition, the description “a segment not containing an ionic group” means that the segment may contain a small amount of the ionic group as long as the segment does not adversely affect the effects of the present invention. Hereinafter, “does not contain an ionic group” may be used in the same meaning. The sulfonic acid group-containing polymer derived by deesterifying the sulfonic acid ester group-containing polymer comprising the block copolymer of the present invention contains two or more types of mutually incompatible segment chains, that is, sulfonic acid groups. A hydrophilic segment and a hydrophobic segment not containing an ionic group are linked to form one polymer chain. In block copolymers, the short-chain interaction resulting from repulsion between chemically different segment chains causes phase separation into nano- or micro-domains consisting of each segment chain, and the segment chains are covalently bonded to each other. Each domain is arranged in a specific order by the effect of the long-range interaction resulting from. A higher-order structure created by combining domains composed of segment chains is called a nano- or micro-phase separation structure, and for ion conduction of a polymer electrolyte membrane, the spatial arrangement of ion-conducting segments in the membrane, that is, nano or The microphase separation structure becomes important. Here, the domain means a mass formed by aggregating similar segments in one or a plurality of polymer chains.

  Especially, it is more preferable that the sulfonate group-containing polymer comprising the block copolymer of the present invention further contains one or more linker sites for connecting the segments. Here, the linker is a site connecting the segment (A1) containing a sulfonate group and the segment (A2) containing no ionic group, and a segment containing a sulfonate group ( It is defined as a site having a different chemical structure from A1) and the segment (A2) not containing an ionic group. This linker enables the linkage between different segments while suppressing randomization, segment cleavage and side reactions due to the ether exchange reaction. Necessary for developing a phase separation structure. In the absence of a linker, segment cleavage such as randomization may occur, and the effects of the present invention may not be sufficiently obtained.

By appropriately selecting the chemical structure, segment chain length, molecular weight, ion exchange capacity, etc. of the sulfonic acid ester group-containing polymer comprising the block copolymer of the present invention and the sulfonic acid group-containing polymer obtained by deesterification thereof, It is possible to control various properties such as processability, domain size, crystallinity / amorphity, mechanical strength, proton conductivity, and dimensional stability of the polymer electrolyte material.

Next, a preferable specific example is given about the block copolymer of this invention. The block copolymer of the present invention has a wide range of humidity conditions as a polymer electrolyte material or a polymer electrolyte membrane by forming a domain of a hydrophilic segment containing a sulfonic acid group obtained by deesterifying a sulfonic acid ester group. Shows high proton conductivity. In the block copolymer containing a sulfonate group of the present invention, the ion exchange capacity when converted to a sulfonate group by deesterification is 0.1 to 5 meq / g from the balance of proton conductivity and water resistance. More preferably, it is 1 meq / g or more, and most preferably 1.4 meq / g or more. Moreover, 3.5 meq / g or less is more preferable, Most preferably, it is 3 meq / g or less. When the ion exchange capacity is less than 0.1 meq / g, proton conductivity may be insufficient, and when it is greater than 5 meq / g, water resistance may be insufficient.

  Here, the ion exchange capacity is the molar amount of sulfonic acid groups introduced per unit dry weight of the block copolymer, polymer electrolyte material, and polymer electrolyte membrane. Indicates a high degree. The ion exchange capacity can be measured by elemental analysis, neutralization titration method or the like. It can also be calculated from the S / C ratio using elemental analysis, but it is difficult to measure when a sulfur source other than sulfonic acid groups is included. Therefore, in the present invention, the ion exchange capacity is defined as a value obtained by the neutralization titration method. The polymer electrolyte material of the present invention and the polymer electrolyte membrane include an embodiment in which the block copolymer of the present invention and other components are included. In this case, the ion exchange capacity is the total amount of the complex. As a standard.

The measurement example of neutralization titration is as follows. The measurement is performed three times or more and the average value is taken.
(1) After wiping off the moisture on the surface of the electrolyte membrane that has been proton-substituted and thoroughly washed, vacuum-dry at 100 ° C. for 12 hours or longer to obtain the dry weight.
(2) Add 50 mL of 5 wt% sodium sulfate aqueous solution to the electrolyte, and leave it for 12 hours to exchange ions.
(3) The resulting sulfuric acid is titrated with 0.01 mol / L sodium hydroxide aqueous solution. A commercially available phenolphthalein solution for titration 0.1 w / v% is added as an indicator, and the point at which it becomes light reddish purple is the end point.
(4) The ion exchange capacity is determined by the following formula.

Ion exchange capacity (meq / g) =
[Concentration of sodium hydroxide aqueous solution (mmol / ml) × Drip amount (ml)] / Dry weight of sample (g)
The molecular weight of the block copolymer of the present invention thus obtained is 50,000 to 1,000,000, preferably 100,000 to 600,000 in terms of polystyrene-converted weight average molecular weight. If it is less than 50,000, any of mechanical strength, physical durability, and solvent resistance may be insufficient, such as cracking in the molded film. On the other hand, if it exceeds 1,000,000, the solubility may be insufficient, the solution viscosity may be high, and the processability may be deteriorated.

  As the block copolymer of the present invention, the molar composition ratio (A1 / A2) of the segment (A1) containing a sulfonate group and the segment (A2) containing no ionic group is 0.2 or more. Is more preferably 0.33 or more, and most preferably 0.5 or more. Moreover, 5 or less is more preferable, 3 or less is more preferable, and 2.5 or less is the most preferable. When the molar composition ratio A1 / A2 is less than 0.2 or exceeds 5, the effect of the present invention may be insufficient, proton conductivity under low humidification conditions may be insufficient, This is not preferable because physical durability may be insufficient. Here, the molar composition ratio (A1 / A2) represents the ratio of the number of moles of repeating units present in the segment (A1) to the number of moles of repeating units present in the segment (A2). In addition, for example, when the segment (A1) containing a sulfonic acid ester group is composed of a structural unit (P1) containing a sulfonic acid ester group, the molar calculation is the molecular weight of the corresponding structural unit (P1) with the number average molecular weight of the segment. However, the present invention is not limited to this example.

  The ion exchange capacity of the segment containing the sulfonic acid group obtained by deesterifying the segment (A1) containing the sulfonic acid ester group is preferably high, more preferably from the viewpoint of proton conductivity under low humidification conditions. Is 2.0 meq / g or more, more preferably 2.5 meq / g or more, and most preferably 3.0 meq / g or more. Moreover, 6 meq / g or less is more preferable, 4.5 meq / g or less is more preferable, Most preferably, it is 4.0 meq / g or less. When the ion exchange capacity of the segment containing the sulfonic acid group obtained by deesterifying the segment (A1) containing the sulfonic acid ester group is less than 2.0 meq / g, the proton conductivity under the low humidification condition is If it exceeds 6 meq / g, the hot water resistance and physical durability may be insufficient.

  The ion exchange capacity of the segment (A2) containing no ionic group is preferably low from the viewpoint of hot water resistance, mechanical strength, dimensional stability, and physical durability, more preferably 1 meq / g or less, and still more preferably 0.5 meq / g, most preferably 0.1 meq / g or less. When the ion exchange capacity of the segment (A2) not containing an ionic group exceeds 1 meq / g, the hot water resistance, mechanical strength, dimensional stability, and physical durability may be insufficient.

  As a segment that does not contain an ionic group, a structural unit that is chemically stable and exhibits crystallinity due to strong intermolecular cohesion is more preferable, and a block co-polymer with excellent mechanical strength, dimensional stability, and physical durability. Coalescence can be obtained.

  That is, in the present invention, it is particularly preferable that the structural unit not containing the ionic group is represented by the following general formula (P2).

(In the general formula (P2), Ar ^{1 to} Ar ⁴ represent an arbitrary divalent arylene group and may be optionally substituted, but do not contain an ionic group. Ar ^{1 to} Ar ⁴ are independent of each other. Two or more types of arylene groups may be used, and * represents a bonding site with the general formula (P2) or other structural unit.)
Here, preferable divalent arylene groups as Ar ^{1 to} Ar ⁴ are hydrocarbon arylene groups such as phenylene group, naphthylene group, biphenylene group, and fluorenediyl group, and heteroarylenes such as pyridinediyl, quinoxalinediyl, and thiophenediyl. Examples include, but are not limited to, groups. Ar ^{1 to} Ar ⁴ do not contain an ionic group and may be substituted with a group other than the ionic group, but the non-substituted one has proton conductivity, chemical stability, and physical durability. More preferable in terms. Furthermore, a phenylene group is preferable, and a p-phenylene group is most preferable. As a more preferable specific example of the structural unit represented by the general formula (P2) contained in the segment (A2) not containing an ionic group, a structure represented by the following general formula (O1) in terms of raw material availability Units are listed. Among these, from the viewpoint of mechanical strength due to crystallinity, dimensional stability, and physical durability, a structural unit represented by the following formula (P3) is more preferable. As content of the structural unit represented by general formula (P2) contained in the segment (A2) which does not contain an ionic group, the more one is preferable, 20 mol% or more is more preferable, 50 mol% or more is more preferable. More preferably, 80 mol% or more is most preferable. When the content is less than 20 mol%, the effects of the present invention on the mechanical strength, dimensional stability, and physical durability due to crystallinity may be insufficient, which is not preferable.

  As the segment (A2) not containing an ionic group, a preferred example of a structural unit that is copolymerized in addition to the structural unit represented by the general formula (P2) is an aromatic polyether polymer containing a ketone group, that is, What has a structural unit shown by general formula (Q1), and does not contain an ionic group is mentioned.

(Z ¹ and Z ² in the general formula (Q1) each represent a divalent organic group containing an aromatic ring, and each of them may represent two or more groups, but does not include an ionic group. Each independently represents a positive integer.)
As preferred organic groups as Z ¹ and Z ² in the general formula (Q1), Z ¹ is a phenylene group, and Z ² is the following general formula (X-1), (X-2), (X-4) , (X-5) is more preferable. Moreover, although you may substitute by groups other than an ionic group, the direction where it is unsubstituted is more preferable at the point of crystallinity provision. Z ¹ and Z ² are more preferably a phenylene group, most preferably a p-phenylene group.

(The groups represented by the general formulas (X-1), (X-2), (X-4), and (X-5) may be optionally substituted with a group other than an ionic group). .

  Specific examples of the structural unit represented by the general formula (Q1) include the structural units represented by the following general formulas (Q2) to (Q7), but are not limited thereto. It is possible to select appropriately in consideration of crystallinity and mechanical strength. Among these, from the viewpoint of crystallinity and production cost, the structural unit represented by the general formula (Q1) is more preferably the following general formulas (Q2), (Q3), (Q6), and (Q7). Formulas (Q2) and (Q7) are most preferable.

(General formulas (Q2) to (Q7) are all represented in the para position, but may have other bonding positions such as ortho and meta positions as long as they have crystallinity. The para position is more preferable from the viewpoint of

As in the case of (P1), a protective group is introduced into the dihydric phenol compound in order to obtain a segment not containing the ionic group represented by the general formulas (P2), (Q1), and (P3) of the present invention. It is also preferable to deprotect after polymerization or molding and convert the structure to the structure represented by the general formula (P2), (Q1), or (P3). Preferred specific examples of the dihydric phenol compound having a protecting group include compounds represented by the above general formulas (r1) to (r10), and these dihydric phenol compounds from the viewpoint of reactivity and chemical stability. Derivatives can be mentioned. Among these dihydric phenol compounds, the compounds represented by the general formulas (r4) to (r10) are more preferable from the viewpoint of stability, and more preferably the compounds represented by the general formulas (r4), (r5), and (r9). The compound represented by the general formula (r4) is most preferred. The number average molecular weight of the segment containing a sulfonic acid ester group and the segment not containing an ionic group is related to the domain size of the phase separation structure. From the balance between proton conductivity and physical durability at low humidification, the number average molecular weight is 0. More preferably, it is 50,000 or more, more preferably 10,000 or more, and most preferably 15,000 or more. Moreover, 50,000 or less is more preferable, More preferably, it is 40,000 or less, Most preferably, it is 30,000 or less.

  The block copolymer of the present invention can observe a co-continuous or lamellar-like phase separation structure by transmission electron microscope observation by controlling the segment length ratio. By controlling the phase separation structure of the block copolymer, that is, the aggregation state and the shape of the segments containing sulfonic acid groups derived from sulfonic acid ester groups by deesterification and the segments not containing ionic groups, Excellent proton conductivity can be achieved even under humidified conditions. The phase separation structure can be analyzed with a transmission electron microscope (TEM), an atomic force microscope (AFM), or the like.

  As the block copolymer of the present invention, when observed by TEM at 50,000 times, a phase separation structure is observed, and the average interlayer distance or average interparticle distance measured by image processing is 8 nm or more and 300 nm or less. Some are preferred. Among these, the average interlayer distance or the average interparticle distance is more preferably 10 nm or more and 100 nm or less, and most preferably 15 nm or more and 50 nm or less. When the phase separation structure is not observed by a transmission electron microscope, or when the average interlayer distance or the average interparticle distance is less than 8 nm, the continuity of the ion channel may be insufficient and the conductivity may be insufficient. Absent. Further, when the interlayer distance exceeds 5000 nm, the mechanical strength and dimensional stability may be deteriorated, which is not preferable.

The deesterification method for derivatizing a sulfonate group-containing polymer according to the present invention into a corresponding sulfonate ester-containing polymer includes, for example,
(1) A method of reacting the sulfonic acid ester group-containing polymer in a strong acid such as trifluoroacetic acid at a temperature of about 80 to 120 ° C. for about 5 to 10 hours. (2) An excess amount containing a small amount of hydrochloric acid. A method of adding the sulfonic acid ester group-containing polymer to water or alcohol and stirring for 5 minutes or more (3) 1 to 3 moles of lithium bromide with respect to 1 mol of sulfonic acid ester groups in the sulfonic acid ester group-containing polymer Alternatively, in a solution containing a quaternary halogenated organic ammonium salt, the sulfonic acid ester group-containing polymer is reacted at a temperature of about 80 to 15 ° C. for about 3 to 10 hours, and then subjected to proton substitution by acid addition. Method (4) The sulfonate group-containing polymer is charged into an excess amount of water or alcohol containing a small amount of sodium hydroxide, After stirring over minute, there may be mentioned a method of proton substitution by acid addition, not limited to this example.

  The progress of deesterification can be confirmed by the ion exchange capacity estimated by NMR or the neutralization titration method, and 90% or more of the sulfonic acid ester groups in the polymer are converted to sulfonic acid groups. Is preferred.

  There is no particular limitation on the method of molding the sulfonic acid ester group-containing polymer of the present invention or the sulfonic acid group-containing polymer derived from deesterification into a polymer film, but the method of forming a film from a solution state or forming a film from a molten state The method of doing etc. is possible. Examples of the former include a method of forming a film by dissolving the polymer in a solvent such as N-methyl-2-pyrrolidone, casting the solution on a glass plate or the like, and removing the solvent.

  The solvent used for film formation is not particularly limited as long as it dissolves the polymer and can be removed thereafter. For example, N, N-dimethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone, dimethyl Aprotic polar solvents such as sulfoxide, sulfolane, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphontriamide, ester solvents such as γ-butyrolactone and butyl acetate, carbonate solvents such as ethylene carbonate and propylene carbonate , Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, alkylene glycol monoalkyl ether such as propylene glycol monoethyl ether, or alcohol such as isopropanol Lumpur solvents, water and mixtures thereof is preferably used, is preferred for high highest solubility aprotic polar solvent.

  In the present invention, when a block copolymer is used, the selection of the solvent is important for the phase separation structure, and it is also preferable to use a mixture of an aprotic polar solvent and a low polarity solvent. It is a simple method.

  It is a preferable method to obtain a tough membrane by subjecting the polymer solution prepared to a required solid content concentration to normal pressure filtration or pressure filtration to remove foreign substances present in the polymer electrolyte solution. The filter medium used here is not particularly limited, but a glass filter or a metallic filter is suitable. In the filtration, the pore size of the minimum filter through which the polymer solution passes is preferably 1 μm or less. If filtration is not carried out, foreign matter is allowed to enter, and film breakage occurs or durability becomes insufficient.

  In the present invention, the method for deprotecting at least a part of the ketone moiety protected with an acetal and / or ketal group to form a ketone moiety is not particularly limited. The deprotection reaction can be carried out in the presence of water and acid under non-uniform or uniform conditions, but from the viewpoint of mechanical strength and solvent resistance, it is acid-treated after being formed into a film or the like. The method is more preferred. Specifically, it is possible to deprotect the molded membrane by immersing it in an aqueous sulfuric acid solution, and the acid concentration and the aqueous solution temperature can be appropriately selected.

  The weight ratio of the acidic aqueous solution required for the polymer is preferably 1 to 100 times, but a larger amount of water can be used. The acid catalyst is preferably used at a concentration of 0.1 to 50% by weight of water present. Suitable acid catalysts include strong mineral acids such as hydrochloric acid, nitric acid, fluorosulfonic acid, sulfuric acid, and strong organic acids such as p-toluenesulfonic acid, trifluoromethane sulfonic acid, and the like. Depending on the film thickness of the polymer and the like, the amount of acid catalyst and excess water, reaction pressure, and the like can be selected as appropriate.

  For example, in the case of a film having a thickness of 50 μm, almost all of the film can be easily deprotected by dipping in an acidic aqueous solution as exemplified by a 6N hydrochloric acid aqueous solution and heating at 95 ° C. for 1 to 48 hours. It is. Further, even when immersed in a 1N aqueous hydrochloric acid solution at 25 ° C. for 24 hours, most of the protecting groups can be deprotected. However, the deprotection conditions are not limited to these, and the deprotection may be performed using an acid gas, an organic acid, or the like, or may be performed by heating.

  In the present invention, the step of deriving into a sulfonic acid group by deesterification is not particularly limited, and may be carried out at any stage before or after molding into a film shape, etc. In view of the solubility of the polymer, it is preferable to deesterify after molding. The method of deesterification follows the said method.

  The sulfonic acid group-containing polymer of the present invention is suitable as a polymer electrolyte material, and particularly preferably used as a polymer electrolyte molded article. In the present invention, the polymer electrolyte molded body means a molded body containing the polymer electrolyte material of the present invention. The polymer electrolyte molded body of the present invention includes membranes (including films and films), plates, fibers, hollow fibers, particles, lumps, micropores, coatings, and foams. It can take various forms depending on the intended use. The polymer can be applied to a wide range of applications because it can improve the design freedom of the polymer and improve various properties such as mechanical properties and solvent resistance. It is particularly suitable when the polymer electrolyte molded body is a membrane.

  The polymer electrolyte molded body of the present invention is preferably heat treated, at least in terms of the stability of the sulfonic acid group, preferably in the state of the sulfonic acid ester group, in terms of mechanical properties and water resistance, Furthermore, it is more preferable to heat-treat after at least a part of the protecting group is derived into a ketone group by deprotection. When heat treatment is carried out after derivatization to sulfonic acid groups by deesterification, deterioration of the electrolyte material such as desulfonization tends to occur due to the thermal stability of the sulfonic acid groups. Further, when deprotection is not performed before heat treatment, the protective group may cause insufficient packing properties of the molecular chains, resulting in insufficient mechanical properties and water resistance.

  The temperature of the heat treatment is preferably 150 to 600 ° C, more preferably 160 to 450 ° C, and particularly preferably 180 to 400 ° C. The heat treatment time is preferably 10 seconds to 12 hours, more preferably 30 seconds to 6 hours, and most preferably 1 minute to 1 hour. If the heat treatment temperature is too low, the molecular chain packing property becomes insufficient, and the fuel permeability suppressing effect, the mechanical properties such as the elastic modulus and the breaking strength, and the water resistance are insufficient. On the other hand, when the temperature is too high, the electrolyte material tends to deteriorate. If the heat treatment time is less than 10 seconds, the effect of the heat treatment is insufficient, and if it exceeds 12 hours, the electrolyte material tends to deteriorate.

  The sulfonic acid ester group-containing polymer electrolyte molded body obtained by heat treatment can be converted into sulfonic acid groups as necessary, and in particular, protons can be obtained by carrying out stepwise steps in the order of deprotection, heat treatment, and deesterification. It is possible to achieve a balance between conductivity and fuel cutoff, mechanical properties, long-term durability, and solvent resistance in a better balance. In order to separate deprotection and deesterification stepwise, the above method can be suitably used depending on the stability of the ester group used. For example, in the case of a phenyl ester group, since the reaction hardly proceeds in the method of deesterification with hydrochloric acid described in (2) above, it can be carried out separately from the deprotection reaction, but is not limited to this example.

  In the present invention, examples of the method for performing the heat treatment include a heating gas using a heating press, a heating oven, and a heating plate, a method using contact heating, and the like. However, the method is not limited to these examples and can be performed.

  When the polymer electrolyte material of the present invention is used for a polymer electrolyte fuel cell, a polymer electrolyte membrane and an electrode catalyst layer are suitable. Among them, it is preferably used for a polymer electrolyte membrane. This is because when used for a polymer electrolyte fuel cell, it is usually used as a polymer electrolyte membrane or an electrode catalyst layer binder in the form of a membrane.

  The molded polymer electrolyte of the present invention can be applied to various uses. For example, extracorporeal circulation column, medical use such as artificial skin, filtration use, ion exchange resin use such as chlorine-resistant reverse osmosis membrane, various structural materials use, electrochemical use, humidification membrane, anti-fogging membrane, antistatic membrane, Applicable to solar cell membranes and gas barrier materials. It is also suitable as an artificial muscle and actuator material. Among these, it can be preferably used for various electrochemical applications. Examples of the electrochemical application include a fuel cell, a redox flow battery, a water electrolysis device, a chloroalkali electrolysis device, and the like, among which the fuel cell is most preferable.

  The thickness of the polymer electrolyte membrane obtained by the present invention is preferably 1 to 2000 μm. In order to obtain the mechanical strength and physical durability of the membrane that can withstand practical use, it is more preferably thicker than 1 μm, and in order to reduce membrane resistance, that is, improve power generation performance, it is preferably thinner than 2000 μm. A more preferable range of the film thickness is 3 to 50 μm, and a particularly preferable range is 10 to 30 μm. The film thickness can be controlled by the solution concentration or the coating thickness on the substrate.

  In addition, the polymer electrolyte membrane obtained by the present invention contains additives such as crystallization nucleating agents, plasticizers, stabilizers, antioxidants or mold release agents used in ordinary polymer compounds. It can be added within a range not contrary to the purpose.

  In addition, the polymer electrolyte membrane obtained by the present invention has various polymers, elastomers, and the like for the purpose of improving mechanical strength, thermal stability, workability, etc. within a range that does not adversely affect the above-mentioned various properties. Fillers, fine particles, various additives, and the like may be included. Moreover, you may reinforce with a microporous film, a nonwoven fabric, a mesh, etc.

  A polymer electrolyte fuel cell has a structure in which a hydrogen ion conductive polymer electrolyte membrane is used as an electrolyte membrane, and a catalyst layer, an electrode base material, and a separator are sequentially laminated on both sides thereof. Of these, the catalyst layer laminated on both sides of the electrolyte membrane (that is, the catalyst layer / electrolyte membrane / catalyst layer configuration) is called an electrolyte membrane with a catalyst layer (CCM), and further on both sides of the electrolyte membrane. A catalyst layer and a gas diffusion substrate laminated in sequence (that is, a gas diffusion substrate / catalyst layer / electrolyte membrane / catalyst layer / gas diffusion substrate layer structure) are electrode-electrolyte membrane assemblies or membranes. It is called an electrode assembly (MEA).

  As a manufacturing method of this electrolyte membrane with a catalyst layer, the coating system of apply | coating and drying the catalyst layer paste composition for forming a catalyst layer on the electrolyte membrane surface is generally performed. However, with this coating method, the electrolytic membrane is swollen and deformed by a solvent such as water or alcohol contained in the paste, and there is a problem that it is difficult to form a desired catalyst layer on the electrolyte membrane surface. Moreover, since the electrolytic membrane is also exposed to a high temperature in the drying step, there is a problem that the electrolytic membrane undergoes thermal expansion or the like and is deformed. In order to overcome this problem, there has been proposed a method (transfer method) in which only a catalyst layer is prepared on a substrate in advance and the catalyst layer is transferred to laminate the catalyst layer on the electrolyte membrane (for example, transfer method). JP 2009-9910).

Since the polymer electrolyte membrane obtained by the present invention is tough and excellent in solvent resistance due to crystallinity, it is particularly suitable for use as an electrolyte membrane with a catalyst layer in any of the above coating methods and transfer methods. it can.

  When the MEA is produced by a hot press, there is no particular limitation, and a known method (for example, a chemical plating method described in Electrochemistry, 1985, 53, p.269, edited by the Electrochemical Society (J. Electrochem. Soc. , Electrochemical Science and Technology, 1988, 135, 9, p.2209., Gas diffusion electrode hot press bonding method, etc.) can be applied.

  In the case of integration by heating press, the temperature and pressure may be appropriately selected depending on the thickness of the electrolyte membrane, the moisture content, the catalyst layer, and the electrode substrate. Further, in the present invention, it is possible to form a composite by pressing even when the electrolyte membrane is in a dry state or in a state of absorbing water. Specific press methods include a roll press that defines pressure and clearance, and a flat plate press that defines pressure. From the viewpoint of industrial productivity and suppression of thermal decomposition of a polymer material having a sulfonic acid group, the press method is 0. It is preferable to carry out in the range of from ℃ to 250 ℃. The pressurization is preferably as weak as possible from the viewpoint of electrolyte membrane and electrode protection. In the case of a flat plate press, a pressure of 10 MPa or less is preferable, and the electrode and the electrolyte membrane are stacked without carrying out the complexing by the hot press process. Cell formation is also one of the preferred options from the viewpoint of preventing short-circuiting of the anode and cathode electrodes. In the case of this method, when power generation is repeated as a fuel cell, the deterioration of the electrolyte membrane presumed to be caused by a short-circuited portion tends to be suppressed, and the durability as a fuel cell is improved.

  Furthermore, the application of the solid polymer fuel cell using the polymer electrolyte material and the polymer electrolyte membrane of the present invention is not particularly limited, but a power supply source for a mobile body is preferable. In particular, mobile devices such as mobile phones, personal computers, PDAs, televisions, radios, music players, game machines, headsets, DVD players, human-type and animal-type robots for industrial use, home appliances such as cordless vacuum cleaners, and toys , Electric bicycles, motorcycles, automobiles, buses, trucks and other vehicles and ships, power supplies for mobiles such as railways, stationary primary generators such as stationary generators, or alternatives to these It is preferably used as a hybrid power source.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these. In addition, the measurement conditions of each physical property are as follows.

(1) Measured by ion exchange capacity neutralization titration method. The measurement was performed 3 times and the average value was taken.
1. Moisture on the membrane surface of the electrolyte membrane which had been subjected to proton substitution and was thoroughly washed was wiped off and then vacuum-dried at 100 ° C. for 12 hours or more to obtain a dry weight.
2. 50 mL of 5 wt% sodium sulfate aqueous solution was added to the electrolyte, and ion exchange was performed by allowing to stand for 12 hours.
3. The generated sulfuric acid was titrated with 0.01 mol / L sodium hydroxide aqueous solution. A commercially available phenolphthalein solution for titration (0.1 w / v%) was added as an indicator, and the point at which it turned light reddish purple was used as the end point.
4). The ion exchange capacity was determined by the following formula.
Ion exchange capacity (meq / g) =
[Concentration of sodium hydroxide aqueous solution (mmol / ml) × Drip amount (ml)] / Dry weight of sample (g)
(2) Proton conductivity After immersing the membrane-like sample in pure water at 25 ° C. for 24 hours, it is placed in a constant temperature and humidity chamber, and proton conduction is conducted in the range of 80 ° C. and relative humidity 95% by the constant potential AC impedance method. The humidity dependence of the degree was measured.

  As a measuring apparatus, a Solartron electrochemical measurement system (Solartron 1287 Electrochemical Interface and Solartron 1255B Frequency Response Analyzer) was used, and constant potential impedance measurement was performed by a two-terminal method to determine proton conductivity. The AC amplitude was 50 mV. A sample having a width of 10 mm and a length of 50 mm was used. The measurement jig was made of phenol resin, and the measurement part was opened. As an electrode, a platinum plate (thickness: 100 μm, 2) was used. The electrodes were disposed at a distance of 15 mm between the electrodes, on the front side and the back side of the sample film so as to be parallel to each other and orthogonal to the longitudinal direction of the sample film.

(3) Number average molecular weight, weight average molecular weight The number average molecular weight and the weight average molecular weight of the polymer were measured by GPC. Tosoh's HLC-8022GPC is used as an integrated device of an ultraviolet detector and a differential refractometer, and Tosoh's TSK gel SuperHM-H (inner diameter 6.0 mm, length 15 cm) is used as the GPC column. N-methyl-2 -Measured with a pyrrolidone solvent (N-methyl-2-pyrrolidone solvent containing 10 mmol / L lithium bromide) at a sample concentration of 0.1 wt%, a flow rate of 0.2 mL / min, and a temperature of 40 ° C. The number average molecular weight and the weight average molecular weight were determined.

(4) Film thickness It measured using Mitutoyo ID-C112 type | mold set to Mitutoyo granite comparator stand BSG-20.

(5) Purity analysis of bisphenol compound Quantitative analysis was performed by gas chromatography (GC) under the following conditions.
Column: DB-5 (manufactured by J & W) L = 30m Φ = 0.53mm D = 1.50μm
Carrier: Helium (Linear velocity = 35.0 cm / sec)
Analysis conditions Inj. temp. 300 ° C
Dect. temp. 320 ° C
Oven 50 ° C x 1 min
Rate 10 ℃ / min
Final 300 ℃ × 15min
SP ratio 50: 1
(6) Nuclear magnetic resonance spectrum (NMR)
NMR measurement was performed under the following measurement conditions, and the structure of the aromatic sulfonic acid derivative was confirmed.

Device: EX-270
Resonance frequency: 270 MHz (1H-NMR)
Measurement temperature: room temperature Dissolving solvent: DMSO-d6
Internal reference material: TMS (0 ppm)
Number of integrations: 16 times (7) Hot water resistance The hot water resistance of the electrolyte membrane was evaluated by measuring the dimensional change rate in hot water at 95 ° C. The electrolyte membrane was cut into a strip having a length of about 5 cm and a width of about 1 cm, immersed in water at 25 ° C. for 24 hours, and the length (L1) was measured with a caliper. The electrolyte membrane was immersed in hot water at 95 ° C. for 8 hours, and then the length (L2) was measured again with a caliper, and the size change was visually observed.

(8) Observation of phase separation structure by transmission electron microscope (TEM) A sample piece was immersed in a 2 wt% lead acetate aqueous solution as a staining agent and left at 25 ° C. for 48 hours. A dyed sample was taken out, embedded in a visible curable resin, and fixed by irradiation with visible light for 30 seconds.

  A 100 nm flake was cut at room temperature using an ultramicrotome, and the obtained flake was collected on a Cu grid and used for TEM observation. Observation was carried out at an acceleration voltage of 100 kV, and photography was carried out so that the photographic magnification was × 8,000, × 20,000, and × 100,000. As a device, TEM H7100FA (manufactured by Hitachi, Ltd.) was used.

Synthesis example 1
Synthesis of 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane (K-DHBP) represented by the following formula (G1)

  A 500 ml flask equipped with a stirrer, thermometer and distillation tube was charged with 49.5 g of 4,4'-dihydroxybenzophenone, 134 g of ethylene glycol, 96.9 g of trimethyl orthoformate and 0.50 g of p-toluenesulfonic acid monohydrate. did. Thereafter, the mixture was stirred while maintaining at 78 to 82 ° C. for 2 hours. Further, the internal temperature was gradually raised to 120 ° C. and heated until the distillation of methyl formate, methanol, and trimethyl orthoformate completely stopped. After cooling this reaction liquid to room temperature, the reaction liquid was diluted with ethyl acetate, the organic layer was washed with 100 ml of 5% aqueous potassium carbonate solution and separated, and then the solvent was distilled off. Crystals were precipitated by adding 80 ml of dichloromethane to the residue, filtered and dried to obtain 52.0 g of 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane. GC analysis of the crystals revealed 99.8% 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane and 0.2% 4,4'-dihydroxybenzophenone.

Synthesis example 2
Synthesis of disodium-3,3′-disulfonate-4,4′-difluorobenzophenone represented by the following formula (G2)

109.1 g (Aldrich reagent) of 4,4′-difluorobenzophenone was reacted at 100 ° C. for 10 hours in 150 mL of fuming sulfuric acid (50% SO ₃ ) (Wako Pure Chemicals reagent). Thereafter, the mixture was poured little by little into a large amount of water, neutralized with NaOH, and 200 g of sodium chloride was added to precipitate the composite. The resulting precipitate was filtered off and recrystallized with an aqueous ethanol solution to obtain disodium 3,3′-disulfonate-4,4′-difluorobenzophenone represented by the above general formula (G2). The purity was 99.3%. The structure was confirmed by ¹ H-NMR. Impurities were quantitatively analyzed by capillary electrophoresis (organic matter) and ion chromatography (inorganic matter).

Example 1
(Synthesis of an aromatic sulfonic acid ester derivative represented by the following formula (G3))

In a 1 L flask equipped with a stirrer, 133 g of 3,3′-disulfonate-4,4′-difluorobenzophenone was weighed in a nitrogen stream, dissolved in 330 mL of acetonitrile and 250 mL of sulfolane, and further added 290 g of phosphoryl trichloride. After heating at reflux for 20 hours, 20 mL of N, N-dimethylacetamide was added and the mixture was heated to reflux for 16 hours. After cooling with ice, 1.5 L of cold water was added, and the resulting precipitate was collected by filtration and washed with 500 mL of cold water. The precipitate was dried at room temperature under reduced pressure and recrystallized with toluene at 300 mL to obtain 65 g of 5,5′-carbonylbis (2-fluorobenzene-1-sulfonyl chloride). The structure was confirmed by ¹ H-NMR.

Under a nitrogen stream, 5,5′-carbonylbis (2-fluoro) was added to a mixed solution of 86.7 g of 2,2-dimethyl-1-propanol and 99.7 g of pyridine while cooling with an ice bath to 5 ° C. or lower. 50.0 g of benzene-1-sulfonyl chloride) was gradually added. Then, it heated up to room temperature and added 600 mL of water made to react for 2 hours, and extracted with 900 mL of ethyl acetate. After washing with 600 mL of 5% aqueous hydrochloric acid, 300 mL of 5% aqueous NaOH and 600 mL of saturated aqueous NaCl, the organic layer was dried over sodium sulfate. The solvent was distilled off using an evaporator, and the resulting crude product was recrystallized from ethyl acetate / hexane to obtain 31.0 of a sulfonic acid ester derivative (G3). The structure was confirmed by ¹ H-NMR.

  Example 2

32.1 g of a sulfonic acid ester derivative (G4) was synthesized in the same manner as in Example 1 except that 120.2 g of 4-ethylphenol was added instead of 2,2-dimethyl-1-propanol. The structure was confirmed by ¹ H-NMR.

  Example 3

29.6 g of a sulfonic acid ester derivative (G5) was synthesized in the same manner as in Example 1 except that 93.8 g of 4-hydroxypyridine was added instead of 2,2-dimethyl-1-propanol. The structure was confirmed by ¹ H-NMR.

  Example 4

127.1 g (Tokyo Kasei Reagent) of 4,4′-difluorodiphenylsulfone was reacted at 150 ° C. for 10 hours in 150 mL of fuming sulfuric acid (50% SO ₃ ) (Wako Pure Chemical Reagent). Thereafter, the mixture was poured little by little into a large amount of water, neutralized with NaOH, and 200 g of sodium chloride was added to precipitate the composite. The resulting precipitate was filtered off and recrystallized with an aqueous ethanol solution to obtain disodium 3,3′-disulfonate-4,4′-difluorodiphenylsulfone. The purity was 99.3%. The structure was confirmed by ¹ H-NMR. Impurities were quantitatively analyzed by capillary electrophoresis (organic matter) and ion chromatography (inorganic matter).

In a 1 L flask equipped with a stirrer, 144 g of 3,3′-disulfonate-4,4′-difluorodiphenylsulfone was weighed in a nitrogen stream, dissolved in 330 mL of acetonitrile and 250 mL of sulfolane, and further added 290 g of phosphoryl trichloride, After heating to reflux for 2 hours, 20 mL of N, N-dimethylacetamide was added and heated to reflux for 16 hours. After cooling with ice, 1.5 L of cold water was added, and the resulting precipitate was collected by filtration and washed with 500 mL of cold water. The precipitate was dried under reduced pressure at room temperature and recrystallized with toluene at 300 mL to obtain 71 g of 5,5′-sulfonylbis (2-fluorobenzene-1-sulfonyl chloride). The structure was confirmed by ¹ H-NMR.

Under a nitrogen stream, 5,5′-carbonylbis (2-fluoro) was added to a mixed solution of 86.7 g of 2,2-dimethyl-1-propanol and 99.7 g of pyridine while cooling with an ice bath to 5 ° C. or lower. Benzene-1-sulfonyl chloride (54.3 g) was gradually added. Then, it heated up to room temperature and added 600 mL of water made to react for 2 hours, and extracted with 900 mL of ethyl acetate. After washing with 600 mL of 5% aqueous hydrochloric acid, 300 mL of 5% aqueous NaOH and 600 mL of saturated aqueous NaCl, the organic layer was dried over sodium sulfate. The solvent was distilled off using an evaporator, and the resulting crude product was recrystallized from ethyl acetate / hexane to obtain 33.0 of a sulfonic acid ester derivative (G6). The structure was confirmed by ¹ H-NMR.
Example 5
(Sulphonic acid group-containing polymer represented by the following general formula (G7) using (G3) as the sulfonic acid ester derivative)

  In a 500 mL three-necked flask equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark trap, 15.6 g of potassium carbonate (Aldrich reagent, 113 mmol), 12.9 g (50 mmol) of K-DHBP obtained in Synthesis Example 1, and the above example 27.2 g (52.5 mmol) of the sulfonate derivative (G3) obtained in 1 was added, and after nitrogen substitution, dehydration was performed at 180 ° C. in 150 mL of N-methylpyrrolidone (NMP) and 50 mL of toluene, and the temperature was raised. Toluene was removed and polymerization was carried out at 210 ° C. for 6 hours. Purification was performed by reprecipitation in a large amount of isopropyl alcohol to obtain a precursor polymer having a ketal group and a sulfonate group. The weight average molecular weight was 400,000.

  A 25 wt% N-methylpyrrolidone (NMP) solution in which the obtained precursor polymer was dissolved was subjected to pressure filtration using a glass fiber filter, cast onto a glass substrate, dried at 100 ° C. for 4 h, Heat treatment was performed at 150 ° C. for 10 minutes under nitrogen to obtain a polyketal ketone film (film thickness: 24 μm). The solubility of the polymer was very good. It was immersed in a 10% by weight sulfuric acid aqueous solution at 60 ° C. for 24 hours, followed by a deprotection reaction, followed by immersion in a 95 ° C. lithium bromide aqueous solution to proceed with a deesterification reaction, hydrochloric acid treatment, a large excess amount of pure It was immersed in water for 24 hours and sufficiently washed to obtain a polymer electrolyte membrane comprising a sulfonic acid group-containing polymer represented by the above formula (G7). The resulting membrane had a sulfonic acid group density of 3.6 meq / g. The proton conductivity was 530 mS / cm at 80 ° C. and 85% relative humidity, and 0.3 mS / cm at 80 ° C. and 25% relative humidity. Since the sulfonic acid group density was high, the dimensional change rate was as large as 50%, but it was a relatively tough film due to the effect of high molecular weight, and it was a transparent and uniform film visually. In addition, the presence of ketal group and ester group was not observed in NMR.

Example 6
(Sulphonic acid group-containing polymer represented by the general formula (G7) using the (G4) as the sulfonic acid ester derivative)
A precursor polymer having a ketal group and a sulfonate group was obtained in the same manner as in Example 5 except that 30.8 g of (G4) was added instead of the sulfonate derivative (G3). The weight average molecular weight was 410,000.

  The obtained precursor polymer was formed into a film by the same method as in Example 5 to obtain a polymer electrolyte membrane made of a sulfonic acid group-containing polymer represented by the above formula (G7). The resulting membrane had a sulfonic acid group density of 3.5 meq / g.

  The proton conductivity was 520 mS / cm at 80 ° C. and 85% relative humidity, and 0.25 mS / cm at 80 ° C. and 25% relative humidity. Since the sulfonic acid group density was high, the dimensional change rate was as large as 47%, but it was a relatively tough film due to the effect of high molecular weight, and it was a transparent and uniform film visually. In addition, the presence of ketal group and ester group was not observed in NMR.

Example 7
(Sulphonic acid group-containing polymer represented by the general formula (G7) using the above (G5) as a sulfonic acid ester derivative)
A precursor polymer having a ketal group and a sulfonate group was obtained in the same manner as in Example 5 except that 28.0 g of (G5) was used instead of the sulfonate derivative (G3). The weight average molecular weight was 430,000.

  The obtained precursor polymer was formed into a film by the same method as in Example 5 to obtain a polymer electrolyte membrane made of a sulfonic acid group-containing polymer represented by the above formula (G7). The resulting membrane had a sulfonic acid group density of 3.6 meq / g.

The proton conductivity was 530 mS / cm at 80 ° C. and 85% relative humidity, and 0.3 mS / cm at 80 ° C. and 25% relative humidity. Since the sulfonic acid group density was high, the dimensional change rate was as high as 45%, but it was a relatively tough film due to the effect of high molecular weight, and it was a transparent and uniform film visually. Further, the presence of ketal group and ester group was not observed in NMR Example 8
(Sulphonic acid group-containing polymer represented by the general formula (G8) using (G3) as a sulfonic acid ester derivative)

The ketal group and the sulfonate group were changed in the same manner as in Example 5 except that K-DHBP was changed from 12.9 g to 6.45 g (25 mmol), and 4.66 g (25 mmol) of 4,4′-biphenol was added. A precursor polymer having was obtained. The weight average molecular weight was 380,000.

  The obtained precursor polymer was formed into a film by the same method as described in Example 5 to obtain a polymer electrolyte membrane composed of a sulfonic acid group-containing polymer represented by the above formula (G8). The resulting membrane had a sulfonic acid group density of 3.5 meq / g.

  The proton conductivity was 510 mS / cm at 80 ° C. and 85% relative humidity, and 0.25 mS / cm at 80 ° C. and 25% relative humidity. Since the sulfonic acid group density was high, the dimensional change rate was as large as 51%, but it was a relatively tough film due to the effect of high molecular weight, and it was a transparent and uniform film visually. In addition, the presence of ketal group and ester group was not observed in NMR.

Example 9
(Sulphonic acid group-containing polymer represented by the general formula (G9) using the above (G3) as a sulfonic acid ester derivative)

  The ketal group and sulfonic acid ester were changed in the same manner as in Example 5 except that K-DHBP was changed from 12.9 g to 6.45 g (25 mmol) and 4.0 g (25 mmol) of 2,6-dihydroxynaphthalene was added. A precursor polymer having groups was obtained. The weight average molecular weight was 370,000.

The obtained precursor polymer was formed into a film by the same method as in Example 5 to obtain a polymer electrolyte membrane made of a sulfonic acid group-containing polymer represented by the above formula (G9). The resulting membrane had a sulfonic acid group density of 3.6 meq / g.

The proton conductivity was 520 mS / cm at 80 ° C. and 85% relative humidity, and 0.2 mS / cm at 80 ° C. and 25% relative humidity. Since the sulfonic acid group density was high, the dimensional change rate was as large as 52%, but it was a relatively tough film due to the effect of high molecular weight, and it was a transparent and uniform film visually. In addition, the presence of ketal group and ester group was not observed in NMR. Example 10 (Synthesis of oligomer a1 ′ not containing an ionic group represented by the following general formula (G10))
In a 1000 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, and a Dean-Stark trap, 16.59 g of potassium carbonate (Aldrich reagent, 120 mmol), 25.8 g (100 mmol) of K-DHBP obtained in Synthesis Example 1 and 4,4 20.3 g of '-difluorobenzophenone (Aldrich reagent, 93 mmol) was added, purged with nitrogen, dehydrated at 160 ° C. in 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene, heated to remove toluene, 1 at 180 ° C. Time polymerization was performed. Reprecipitation purification was performed in a large amount of methanol to obtain an oligomer a1 (terminal: hydroxyl group) containing no ionic group. The number average molecular weight was 10,000.

  In a 500 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, and a Dean-Stark trap, 1.1 g of potassium carbonate (Aldrich reagent, 8 mmol) and 20.0 g of the oligomer a1 not containing an ionic group (terminal: hydroxyl group) (2 mmol) was added, and after nitrogen substitution, dehydration was performed at 100 ° C. in 100 mL of N-methylpyrrolidone (NMP) and 30 mL of cyclohexane, followed by heating to remove cyclohexane, and 4.0 g of decafluorobiphenyl (Aldrich reagent, 12 mmol) was added. The reaction was carried out at 105 ° C. for 1 hour. Purification was performed by reprecipitation with a large amount of isopropyl alcohol to obtain an oligomer a1 '(terminal: fluoro group) not containing an ionic group represented by the following formula (G10). The number average molecular weight was 11000, and the number average molecular weight of the oligomer a1 'not containing an ionic group was determined to be 10400 obtained by subtracting the linker moiety (molecular weight 630).

(Synthesis of oligomer a2 containing an ionic group represented by the following general formula (G11))
In a 1000 mL three-necked flask equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark trap, 27.6 g of potassium carbonate (Aldrich reagent, 200 mmol), 25.8 g (100 mmol) of K-DHBP obtained in Synthesis Example 1, and the above example 48.2 g (93 mmol) of the sulfonic acid ester derivative (G3) obtained in 1 was added, purged with nitrogen, dehydrated at 170 ° C. in 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene, and then heated to remove toluene. Polymerization was carried out at 180 ° C. for 1 hour. Purification was performed by reprecipitation with a large amount of isopropyl alcohol to obtain an oligomer a2 (terminal: hydroxyl group) containing a sulfonate group represented by the following formula (G11). The number average molecular weight was 16000.

(Synthesis of oligomer a2 as segment (A1) containing sulfonate group, oligomer a1 as segment (A2) not containing ionic group, and block copolymer b1 containing octafluorobiphenylene as a linker moiety)
In a 500 mL three-necked flask equipped with a stirrer, a nitrogen introducing tube, and a Dean-Stark trap, 0.56 g of potassium carbonate (Aldrich reagent, 4 mmol) and 16 g (1 mmol) of an oligomer a2 containing a sulfonate group (terminal: hydroxyl group) ), Nitrogen substitution, dehydration at 100 ° C. in 100 mL of N-methylpyrrolidone (NMP) and 30 mL of cyclohexane, heating to remove cyclohexane, and oligomer a1 ′ (terminal: fluoro group) containing no ionic groups 11 g (1 mmol) was added and reacted at 105 ° C. for 24 hours. A block copolymer b1 was obtained by reprecipitation purification into a large amount of isopropyl alcohol. The weight average molecular weight was 490,000 and the number average molecular weight was 150,000.

The obtained block polymer b1 was formed into a film by the method described in Example 5 to obtain a precursor polymer film (film thickness 25 μm). The solubility of the sulfonate group-containing polymer before molding was very good. Subsequently, deprotection, deesterification, proton substitution, and water washing were performed by the method described in Example 5 to obtain a polymer electrolyte membrane composed of a sulfonic acid group-containing block polymer.
The ion exchange capacity determined from neutralization titration is 1.6 meq / g, the molar composition ratio (A1 / A2) determined from ¹ H-NMR is 48 mol / 52 mol = 0.92, the remaining ketal groups and ester groups. Was not recognized. It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 260 mS / cm at 80 ° C. and 85% relative humidity, and 3 mS / cm at 80 ° C. and 25% relative humidity, and was excellent in low humidified proton conductivity. Further, the dimensional change rate was as small as 8%, and the hot water resistance was also excellent. Furthermore, a TEM observation confirmed a co-continuous phase separation structure with a domain size of 21 nm.

Example 11 (Synthesis of oligomer a3 ′ not containing an ionic group represented by the above general formula (G10))
In a 1000 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, and a Dean-Stark trap, 16.59 g of potassium carbonate (Aldrich reagent, 120 mmol), 25.8 g (100 mmol) of K-DHBP obtained in Synthesis Example 1 and 4,4 20.7 g of '-difluorobenzophenone (Aldrich reagent, 95 mmol) was added, purged with nitrogen, dehydrated at 160 ° C. in 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene, heated to remove toluene, 1 at 180 ° C. Time polymerization was performed. Reprecipitation purification was carried out in a large amount of methanol to obtain oligomer a3 (terminal: hydroxyl group) containing no ionic group. The number average molecular weight was 20000.

  In a 500 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, and a Dean-Stark trap, 1.1 g of potassium carbonate (Aldrich reagent, 8 mmol) and 40.0 g of the oligomer a3 not containing an ionic group (terminal: hydroxyl group) (2 mmol) was added, and after nitrogen substitution, dehydration was performed at 100 ° C. in 100 mL of N-methylpyrrolidone (NMP) and 30 mL of cyclohexane, followed by heating to remove cyclohexane, and 4.0 g of decafluorobiphenyl (Aldrich reagent, 12 mmol) was added. The reaction was carried out at 105 ° C. for 1 hour. Purification was performed by reprecipitation with a large amount of isopropyl alcohol to obtain an oligomer a3 ′ (terminal: fluoro group) not containing an ionic group represented by the above formula (G5). The number average molecular weight was 21000, and the number average molecular weight of the oligomer a3 'not containing an ionic group was determined to be 20400, which is obtained by subtracting the linker moiety (molecular weight 630).

(Synthesis of oligomer a4 containing an ionic group represented by the general formula (G11))
In a 1000 mL three-necked flask equipped with a stirrer, a nitrogen inlet tube, and a Dean-Stark trap, 27.6 g of potassium carbonate (Aldrich reagent, 200 mmol), 25.8 g (100 mmol) of K-DHBP obtained in Synthesis Example 1, and the above example 49.2 g (95 mmol) of the sulfonic acid ester derivative (G3) obtained in 1 was added, and after nitrogen substitution, dehydration was performed at 170 ° C. in 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene, and the temperature was raised to remove toluene. Polymerization was carried out at 180 ° C. for 1 hour. Purification was performed by reprecipitation with a large amount of isopropyl alcohol to obtain an oligomer a4 (terminal: hydroxyl group) containing a sulfonate group represented by the above formula (G11). The number average molecular weight was 32,000.

(Synthesis of oligomer a4 as segment (A1) containing sulfonate group, oligomer a3 as segment (A2) not containing ionic group, and block copolymer b2 containing octafluorobiphenylene as a linker moiety)
In a 500 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, and a Dean-Stark trap, 0.56 g of potassium carbonate (Aldrich reagent, 4 mmol) and 32 g (1 mmol) of an oligomer a4 containing a sulfonate group (terminal: hydroxyl group) ), Nitrogen substitution, dehydration at 100 ° C. in 100 mL of N-methylpyrrolidone (NMP) and 30 mL of cyclohexane, followed by heating to remove cyclohexane, oligomer a3 ′ containing no ionic groups (terminal: fluoro group) 21 g (1 mmol) was added and reacted at 105 ° C. for 24 hours. A block copolymer b2 was obtained by reprecipitation purification into a large amount of isopropyl alcohol. The weight average molecular weight was 390,000, and the number average molecular weight was 130,000.

The obtained block polymer b2 was formed into a film by the method described in Example 5 to obtain a precursor polymer film (film thickness 25 μm). The solubility of the sulfonate group-containing polymer before molding was very good. Subsequently, deprotection, deesterification, proton substitution, and water washing were performed by the method described in Example 5 to obtain a polymer electrolyte membrane composed of a sulfonic acid group-containing block polymer.
The ion exchange capacity determined from neutralization titration was 1.7 meq / g, the molar composition ratio (A1 / A2) determined from ¹ H-NMR was 50 mol / 50 mol = 1, and the remaining ketal group and ester group were recognized. I couldn't. It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 300 mS / cm at 80 ° C. and 85% relative humidity, and 3.5 mS / cm at 80 ° C. and 25% relative humidity. The proton conductivity was excellent in low humidification proton conductivity. Further, the dimensional change rate was as small as 9%, and the hot water resistance was also excellent. Furthermore, a TEM observation confirmed a co-continuous phase separation structure with a domain size of 49 nm.

Example 12
(Synthesis of oligomer a4 as segment (A1) containing sulfonate group, oligomer a1 as segment (A2) not containing ionic group, and block copolymer b3 containing octafluorobiphenylene as a linker moiety)
A block copolymer b3 was obtained in the same manner as in Example 11 except that 11 g (1 mmol) of a1 ′ (terminal: fluoro group) was added instead of the oligomer a3 ′ containing no ionic group. The weight average molecular weight was 410,000, and the number average molecular weight was 130,000.

The obtained block polymer b3 was formed into a film by the method described in Example 5 to obtain a precursor polymer film (film thickness 25 μm). The solubility of the sulfonate group-containing polymer before molding was very good. Subsequently, deprotection, deesterification, proton substitution, and water washing were performed by the method described in Example 5 to obtain a polymer electrolyte membrane composed of a sulfonic acid group-containing block polymer.
The ion exchange capacity determined from neutralization titration was 2.5 meq / g, the molar composition ratio determined from ¹ H-NMR (A1 / A2) was 65 mol / 35 mol = 1.86, the remaining ketal groups and ester groups. Was not recognized. It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 520 mS / cm at 80 ° C. and 85% relative humidity, and 3.8 mS / cm at 80 ° C. and 25% relative humidity, and was excellent in low-humidity proton conductivity. Further, the dimensional change rate was relatively small at 18%, and the hot water resistance was also excellent. Furthermore, a phase separation structure with a domain size of 50 nm was confirmed by TEM observation.

Example 13
(Synthesis of oligomer a5 containing an ionic group represented by the general formula (G11))
An oligomer containing a sulfonate group represented by the formula (G11) by the method described in Example 11 except that the sulfonate derivative (G3) obtained in Example 1 was changed to 48.1 g (93 mmol). a5 (terminal: hydroxyl group) was obtained. The number average molecular weight was 40,000.
(Synthesis of oligomer a5 as segment (A1) containing sulfonate group, oligomer a1 as segment (A2) not containing ionic group, and block copolymer b4 containing octafluorobiphenylene as a linker moiety)
A block copolymer b4 was obtained in the same manner as in Example 10 except that 40 g (1 mmol) of a5 (terminal: hydroxyl group) was added instead of the oligomer a2 containing an ionic group. The weight average molecular weight was 400,000 and the number average molecular weight was 130,000.

The obtained block polymer b4 was formed into a film by the method described in Example 5 to obtain a precursor polymer film (film thickness 25 μm). The solubility of the sulfonate group-containing polymer before molding was very good. Subsequently, deprotection, deesterification, proton substitution, and water washing were performed by the method described in Example 5 to obtain a polymer electrolyte membrane composed of a sulfonic acid group-containing block polymer.
The ion exchange capacity determined from neutralization titration was 2.7 meq / g, the molar composition ratio determined from ¹ H-NMR (A1 / A2) was 70 mol / 30 mol = 1.86, the remaining ketal groups and ester groups. Was not recognized. It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 550 mS / cm at 80 ° C. and 85% relative humidity, and 4 mS / cm at 80 ° C. and 25% relative humidity. The proton conductivity was excellent. Further, the dimensional change rate was relatively small at 20%, and the hot water resistance was excellent. Furthermore, a phase separation structure with a domain size of 50 nm was confirmed by TEM observation.

Example 14
A 25 wt% N-methylpyrrolidone (NMP) solution in which the block copolymer b1 described in Example 10 was dissolved was subjected to pressure filtration using a glass fiber filter, and then cast onto a glass substrate at 100 ° C. By drying for 4 hours, a sulfonate group-containing polyketal ketone film (film thickness: 24 μm) was obtained. The solubility of the polymer was very good. Next, it was immersed in a 10% by weight sulfuric acid aqueous solution at 60 ° C. for 24 hours to perform deprotection treatment. By NMR, it was confirmed that a sulfonic acid ester group remained without a ketal group remaining. After carrying out heat treatment at 300 ° C. for 10 minutes under nitrogen, it was subsequently immersed in a 95 ° C. aqueous lithium bromide solution to proceed with the deesterification reaction, treated with hydrochloric acid and immersed in a large excess of pure water for 24 hours. The polymer electrolyte membrane made of a sulfonic acid group-containing polymer was obtained by thoroughly washing.

The ion exchange capacity determined from neutralization titration is 1.6 meq / g, the molar composition ratio (A1 / A2) determined from ¹ H-NMR is 48 mol / 52 mol = 0.92, the remaining ketal groups and ester groups. Was not recognized. It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 300 mS / cm at 80 ° C. and 85% relative humidity, and 3.5 mS / cm at 80 ° C. and 25% relative humidity. The proton conductivity was excellent in low humidification proton conductivity. Further, the dimensional change rate was as small as 2%, and the hot water resistance was also excellent. After deprotection, improvement in fluorocarbon conductivity, hot water resistance, and mechanical properties was confirmed by heat treatment with the sulfonate group remaining. Furthermore, a TEM observation confirmed a co-continuous phase separation structure with a domain size of 17 nm.

Example 15
A 25 wt% N-methylpyrrolidone (NMP) solution in which the block copolymer b1 described in Example 10 was dissolved was subjected to pressure filtration using a glass fiber filter, and then cast onto a glass substrate at 100 ° C. After drying for 4 hours, the mixture was further heat-treated at 300 ° C. for 10 minutes under nitrogen to obtain a sulfonate group-containing polyketal ketone film (film thickness: 24 μm). The solubility of the polymer was very good. NMR confirmed the presence of ketal groups and sulfonic acid ester groups. After immersing the membrane in a 95 ° C. aqueous lithium bromide solution and allowing the deesterification reaction to proceed, the membrane is immersed in a 10% by weight sulfuric acid aqueous solution at 60 ° C. for 24 hours for proton substitution of the sulfonic acid group and deprotection treatment of the ketal The polymer electrolyte membrane made of a sulfonic acid group-containing polymer was obtained by immersing in a large excess amount of pure water for 24 hours and sufficiently washing.

The ion exchange capacity determined from neutralization titration is 1.6 meq / g, the molar composition ratio (A1 / A2) determined from ¹ H-NMR is 48 mol / 52 mol = 0.92, the remaining ketal groups and ester groups. Was not recognized. It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 270 mS / cm at 80 ° C. and a relative humidity of 85%, and 3.1 mS / cm at 80 ° C. and a relative humidity of 25%. The proton conductivity was excellent. Further, the dimensional change rate was as small as 6%, and the hot water resistance was also excellent. By conducting heat treatment at a higher temperature than in Example 10, it was confirmed that fluorocarbon conductivity, hot water resistance, and mechanical properties were improved, but the heat treatment was carried out with the ketal group remaining, so that it was inferior to Example 14. . Furthermore, a TEM observation confirmed a co-continuous phase separation structure with a domain size of 19 nm.

Example 16
(Sulphonic acid group-containing polymer represented by the following general formula (G12) using (G6) as a sulfonic acid ester derivative)

A precursor polymer having a ketal group and a sulfonate group was obtained in the same manner as in Example 5 except that 29.1 g of (G6) was used instead of the sulfonate derivative (G3). The weight average molecular weight was 410,000.

The obtained precursor polymer was formed into a film by the same method as described in Example 5 to obtain a polymer electrolyte membrane composed of a sulfonic acid group-containing polymer represented by the above formula (G12). The resulting membrane had a sulfonic acid group density of 3.5 meq / g.

The proton conductivity was 450 mS / cm at 80 ° C. and 85% relative humidity, and 0.1 mS / cm at 80 ° C. and 25% relative humidity. The dimensional change rate was as high as 68% because it contained a diphenylsulfone skeleton and the sulfonic acid group density was high, but it was a relatively tough film due to the effect of high molecular weight by the ester group, and it was a transparent and uniform film visually. there were. In addition, the presence of ketal group and ester group was not observed in NMR. Comparative Example 1 Various characteristics were evaluated using a commercially available Nafion (registered trademark) NRE211CS membrane (manufactured by DuPont). The ion exchange capacity determined from neutralization titration was 0.9 meq / g. The film was visually transparent and uniform, and a clear phase separation structure was not confirmed by TEM observation. The proton conductivity was 100 mS / cm at 80 ° C. and 85% relative humidity, and 3 mS / cm at 80 ° C. and 25% relative humidity. Moreover, when it was immersed in hot water, it swelled violently, and it was difficult to handle and sometimes it was torn.

Comparative Example 2
(Sulfonic acid group-containing polymer represented by the above general formula (G7)) In a 500 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, and a Dean-Stark trap, 15.6 g of potassium carbonate (Aldrich reagent, 113 mmol), the above synthesis 12.9 g (50 mmol) of K-DHBP obtained in Example 1 and 22.2 g (52.5 mmol) of disodium-3,3′-disulfonate-4,4′-difluorobenzophenone obtained in Synthesis Example 2 were added, and nitrogen substitution was performed. Then, after dehydrating at 180 ° C. in 150 mL of N-methylpyrrolidone (NMP) and 50 mL of toluene, the temperature was raised to remove toluene, and polymerization was carried out at 210 ° C. for 6 hours. Purification was performed by reprecipitation in a large amount of isopropyl alcohol to obtain a precursor polymer having a ketal group. The weight average molecular weight was 180,000.

  The obtained polymer was formed into a film by the method described in Example 2 to obtain a precursor polymer film (film thickness: 24 μm). The coating solution of the sulfonic acid group-containing polymer precursor before molding was visually turbid and inferior to the examples in terms of solubility in organic solvents. Subsequently, after being immersed in a 10% by weight sulfuric acid aqueous solution at 95 ° C. for 24 hours to carry out proton substitution and deprotection reactions, it was immersed in a large excess amount of pure water for 24 hours and washed thoroughly to obtain a high sulfonic acid group-containing polymer. A molecular electrolyte membrane was obtained. The resulting membrane had a sulfonic acid group density of 3.3 meq / g.

The proton conductivity was 430 mS / cm at 80 ° C. and 85% relative humidity, and 0.1 mS / cm at 80 ° C. and 25% relative humidity. Since no ester group was introduced, the molecular weight was low and the sulfonic acid group density was high. Therefore, the dimensional change rate was as large as 70%, and partial elution was observed. The obtained film was visually cloudy. Further, no residual ketal group was observed in NMR.

Comparative Example 3 (Synthesis of oligomer a6 containing an ionic group represented by the following general formula (G13))
In a 1000 mL three-necked flask equipped with a stirrer, a nitrogen introducing tube, and a Dean-Stark trap, 27.6 g of potassium carbonate (Aldrich reagent, 200 mmol), 25.8 g (100 mmol) of K-DHBP obtained in Synthesis Example 1, and the above synthesis example 39.3 g (93 mmol) of disodium-3,3′-disulfonate-4,4′-difluorobenzophenone obtained in Step 2 was added, and after nitrogen substitution, dehydrated at 170 ° C. in 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene. Thereafter, the temperature was raised to remove toluene, and polymerization was carried out at 180 ° C. for 1 hour. Purification was performed by reprecipitation with a large amount of isopropyl alcohol to obtain an oligomer a5 (terminal: hydroxyl group) containing an ionic group represented by the following formula (G13). The number average molecular weight was 16000.

(Synthesis of oligomer a6 as segment (A1) containing ionic group, oligomer a1 as segment (A2) not containing ionic group, and block copolymer b3 containing octafluorobiphenylene as linker moiety)
In a 500 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube and a Dean-Stark trap, 0.56 g of potassium carbonate (Aldrich reagent, 4 mmol) and 16 g (1 mmol) of an oligomer a6 containing an ionic group (terminal: hydroxyl group) After substitution with nitrogen, dehydration was performed at 100 ° C. in 100 mL of N-methylpyrrolidone (NMP) and 30 mL of cyclohexane, followed by heating to remove cyclohexane, 11 g of oligomer a1 ′ (terminal: fluoro group) not containing an ionic group (1 mmol) was added and reacted at 105 ° C. for 24 hours. A block copolymer b3 was obtained by reprecipitation purification into a large amount of isopropyl alcohol. The weight average molecular weight was 320,000, and the number average molecular weight was 65,000.

The obtained block polymer b3 was formed into a film by the method described in Example 5 to obtain a precursor polymer film (film thickness: 24 μm). The solubility of the sulfonate group-containing polymer before molding was good. Subsequently, deprotection, proton substitution, and water washing were performed by the method described in Comparative Example 2 to obtain a polymer electrolyte membrane composed of a sulfonic acid group-containing block polymer.
The ion exchange capacity determined from neutralization titration was 1.6 meq / g, the molar composition ratio (A1 / A2) determined from ¹ H-NMR was 50 mol / 50 mol = 1, and the remaining ketal groups and ester groups were recognized. I couldn't. It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 240 mS / cm at 80 ° C. and 85% relative humidity, and 2 mS / cm at 80 ° C. and 25% relative humidity, which was excellent in low humidification proton conductivity. It was inferior. Further, the dimensional change rate was as small as 7%, and the hot water resistance was excellent. Furthermore, a TEM observation confirmed a co-continuous phase separation structure with a domain size of 18 nm.

Comparative Example 4 (Synthesis of oligomer a7 containing an ionic group represented by the above general formula (G13))
In a 1000 mL three-necked flask equipped with a stirrer, a nitrogen introducing tube, and a Dean-Stark trap, 27.6 g of potassium carbonate (Aldrich reagent, 200 mmol), 25.8 g (100 mmol) of K-DHBP obtained in Synthesis Example 1, and the above synthesis example 40.1 g (95 mmol) of disodium-3,3′-disulfonate-4,4′-difluorobenzophenone obtained in 2 was added, and after nitrogen substitution, dehydrated at 170 ° C. in 300 mL of N-methylpyrrolidone (NMP) and 100 mL of toluene. Thereafter, the temperature was raised to remove toluene, and polymerization was carried out at 180 ° C. for 1 hour. Purification was performed by reprecipitation with a large amount of isopropyl alcohol to obtain an oligomer a7 (terminal: hydroxyl group) containing an ionic group represented by the general formula (G13). The number average molecular weight was 32,000.

(Synthesis of oligomer a7 as segment (A1) containing ionic group, oligomer a3 as segment (A2) not containing ionic group, and block copolymer b4 containing octafluorobiphenylene as a linker moiety)
In a 500 mL three-necked flask equipped with a stirrer, a nitrogen introduction tube, and a Dean-Stark trap, 0.56 g of potassium carbonate (Aldrich reagent, 4 mmol) and 32 g (1 mmol) of an oligomer a7 (terminal: hydroxyl group) containing an ionic group After substitution with nitrogen, dehydration was performed at 100 ° C. in 100 mL of N-methylpyrrolidone (NMP) and 30 mL of cyclohexane, followed by heating to remove cyclohexane, 21 g of oligomer a3 ′ (terminal: fluoro group) not containing an ionic group (1 mmol) was added and reacted at 105 ° C. for 24 hours. The block copolymer b4 was obtained by reprecipitation purification into a large amount of isopropyl alcohol. The weight average molecular weight was 280,000, and the number average molecular weight was 55,000.

The obtained block polymer b4 was formed into a film by the method described in Example 5 to obtain a precursor polymer film (film thickness 25 μm). The solubility of the ionic group-containing polymer before molding was good. Subsequently, deprotection, proton substitution, and water washing were performed by the method described in Comparative Example 2 to obtain a polymer electrolyte membrane composed of a sulfonic acid group-containing block polymer.
The ion exchange capacity determined from neutralization titration was 1.7 meq / g, the molar composition ratio (A1 / A2) determined from ¹ H-NMR was 48 mol / 52 mol = 0.92, and the ketal group remained. There wasn't. It was an extremely tough electrolyte membrane, and was a transparent and uniform membrane by visual inspection. The proton conductivity was 270 mS / cm at 80 ° C. and 85% relative humidity, and 2.5 mS / cm at 80 ° C. and 25% relative humidity, and was excellent in low humidification proton conductivity. It was inferior to the example. Further, the dimensional change rate was as small as 8%, and the hot water resistance was excellent. Furthermore, a TEM observation confirmed a co-continuous phase separation structure with a domain size of 45 nm.

Comparative Example 5
A sulfonic acid group-containing block polymer was synthesized according to the method described in JP-A-2005-197235 and Example 2.

  (Aromatic sulfonic acid ester derivative represented by the following formula (G14))

In a 1 L flask equipped with a stirrer, 111 g of sodium 3- (2,5-dichlorobenzoyl) benzenesulfonate was weighed in a nitrogen stream, dissolved in 330 mL of acetonitrile and 250 mL of sulfolane, and further added with 290 g of phosphoryl trichloride for 2 hours. After heating to reflux, 20 mL of N, N-dimethylacetamide was added and the mixture was heated to reflux for 16 hours. After cooling with ice, 1.5 L of cold water was added, and the resulting precipitate was collected by filtration and washed with 500 mL of cold water. The precipitate was dried at room temperature under reduced pressure, and recrystallized with toluene at 300 mL to obtain 50.0 g of 3- (2,5-dichlorobenzoyl) benzenesulfonic acid chloride). The structure was confirmed by ¹ H-NMR.

Under a nitrogen stream, 3- (2,5-dichlorobenzoyl) benzene was cooled in a mixed solution of 86.7 g of 2,2-dimethyl-1-propanol and 99.7 g of pyridine while cooling to 5 ° C. or lower with an ice bath. 42.0 g of sulfonic acid chloride) was gradually added. Then, it heated up to room temperature and added 600 mL of water made to react for 2 hours, and extracted with 900 mL of ethyl acetate. After washing with 600 mL of 5% aqueous hydrochloric acid, 300 mL of 5% aqueous NaOH and 600 mL of saturated aqueous NaCl, the organic layer was dried over sodium sulfate. The solvent was distilled off using an evaporator, and the resulting crude product was recrystallized from ethyl acetate / hexane to obtain 24.0 of a sulfonic acid ester derivative (G14). The structure was confirmed by ¹ H-NMR.

(Preparation of oligomer)
To a 1 L three-necked flask equipped with a stirrer, thermometer, Dean-stark tube, nitrogen introducing tube, and cooling tube, 48.8 g of 2,6-dichlorobenzonitrile, 2,2-bis (4-hydroxyphenyl) -1, 1,9.5,3,3-Hexafluoropropane (89.5 g) and potassium carbonate (47.8 g) were weighed. After nitrogen substitution, 346 mL of sulfolane and 173 mL of toluene were added and stirred. The reaction solution was heated to reflux at 150 ° C. in an oil bath. Water produced by the reaction was trapped in a Dean-stark tube. After 3 hours, when almost no water was observed, toluene was removed from the Dean-stark tube out of the system. The reaction temperature was gradually raised to 200 ° C. and stirring was continued for 3 hours. Then, 9.2 g of 2,6-dichlorobenzonitrile was added, and the reaction was further continued for 5 hours.

The reaction solution was allowed to cool, and diluted with 100 mL of toluene. Insoluble matter was filtered, and the filtrate was poured into 2 L of methanol to precipitate the product. The precipitated product was filtered and dried, then dissolved in 250 mL of tetrahydrofuran, and poured into 2 L of methanol for reprecipitation. The precipitated white powder was filtered and dried to obtain 101 g of the desired product. The number average molecular weight was 80,000. The structure was confirmed by ¹ H-NMR.

(Sulfonated polyarylene)
In a 1 L three-necked flask equipped with a stirrer, a thermometer, and a nitrogen inlet tube, 135.2 g of neopentyl 3- (2,5-dichlorobenzoyl) benzenesulfonate, oligomer obtained by the above method (number average molecular weight 90,000) 48 0.7 g, 6.71 g of bis (triphenylphosphine) nickel dichloride, 1.54 g of sodium iodide, 35.9 g of triphenylphosphine, and 53.7 g of zinc were weighed and replaced with dry nitrogen. To this was added 430 mL of N, N-dimethylacetamide (DMAc), and stirring was continued for 3 hours while maintaining the reaction temperature at 80 ° C. Then, 730 mL of DMAc was added for dilution, and insoluble matter was filtered off. The weight average molecular weight was 250,000. The obtained polymer was formed into a film by the method described in Example 2 to obtain a precursor polymer film (film thickness: 24 μm). The solubility of the sulfonate group-containing polymer before molding was very good. Subsequently, deesterification, proton substitution, and water washing were performed by the method described in Example 5 to obtain a polymer electrolyte membrane composed of a sulfonic acid group-containing block polymer.
The ion exchange capacity determined from neutralization titration was 1.7 meq / g, and no residual ester group was observed by ¹ H-NMR analysis. Although it was a hard and brittle electrolyte membrane, it was a transparent and uniform membrane by visual observation. The proton conductivity was 250 mS / cm at 80 ° C. and 85% relative humidity, and 1.2 mS / cm at 80 ° C. and 25% relative humidity. Further, the dimensional change rate was as large as 40%, and the hot water resistance was inferior to that of the block copolymer examples. Furthermore, a phase separation structure with a domain size of 25 nm was confirmed by TEM observation.

Comparative Example 6
A 25 wt% N-methylpyrrolidone (NMP) solution in which the block copolymer b1 described in Example 10 was dissolved was subjected to pressure filtration using a glass fiber filter, and then cast onto a glass substrate at 100 ° C. After drying for 4 hours, a sulfonate group-containing polyketal ketone membrane (film thickness: 24 μm) was obtained. The solubility of the polymer was very good. After immersing the membrane in a 95 ° C lithium bromide aqueous solution and proceeding with the deesterification reaction, the membrane is treated with a small amount of hydrochloric acid for a short time, immersed in a large excess of pure water for 24 hours and thoroughly washed to contain sulfonic acid groups. A polymer electrolyte membrane made of a polymer was obtained.
By NMR, it was confirmed that the ketal group remained without the sulfonate group remaining. Next, after heat treatment at 300 ° C. for 10 minutes in a nitrogen atmosphere, the ketal was deprotected for 24 hours by immersing it in a 10% by weight sulfuric acid aqueous solution at 60 ° C., and sufficiently immersed in a large excess amount of pure water for 24 hours. By washing, a polymer electrolyte membrane made of a sulfonic acid group-containing polymer was obtained.

The ion exchange capacity determined from neutralization titration was 1.2 meq / g, the molar composition ratio (A1 / A2) determined from ¹ H-NMR was 30 mol / 70 mol = 0.42, the remaining ketal groups and ester groups. Was not recognized. Although it was a relatively tough electrolyte membrane, there were some non-uniform portions visually. The proton conductivity was 150 mS / cm at 80 ° C. and 85% relative humidity, and 0.4 mS / cm at 80 ° C. and 25% relative humidity. Compared with Examples 10, 12, and 13, IEC and low humidified proton conductivity were inferior, suggesting desulfonation and intermolecular cross-linking side reaction by heat treatment after deesterification. The rate of dimensional change was as small as 7%, and the hot water resistance was excellent. Furthermore, a phase separation structure with a domain size of 20 nm was confirmed by TEM observation, but some non-uniform portions were observed.

  The polymer electrolyte material comprising the sulfonic acid ester group-containing polymer of the present invention and the sulfonic acid group-containing polymer obtained by deesterifying the polymer is used in various electrochemical devices (for example, fuel cells, water electrolysis devices, chloroalkali electrolysis devices, etc. ). Among these devices, it is suitable for a fuel cell, and particularly suitable for a fuel cell using hydrogen as a fuel.

  Applications of the polymer electrolyte fuel cell of the present invention are not particularly limited, but are portable devices such as mobile phones, personal computers, PDAs, video cameras, digital cameras, home appliances such as cordless vacuum cleaners, toys, electric bicycles, automatic It is preferably used as a power supply source for vehicles such as motorcycles, automobiles, buses, trucks, etc., moving bodies such as ships, railways, etc., conventional primary batteries such as stationary generators, alternatives to secondary batteries, or hybrid power sources with these. .

Claims (13)

An aromatic sulfonic acid ester derivative represented by the following general formula (M1):

(In formula (M1), Z represents an electron withdrawing group. R represents a hydrocarbon group having 1 to 20 carbon atoms independently for each sulfonate group, and may contain a hetero atom. X ¹ and X ² each represent a halogen atom.) The aromatic sulfonic acid ester derivative according to claim 1, wherein the general formula (M1) is represented by the following general formula (M2).

(In formula (M2), each R independently represents a hydrocarbon group having 1 to 20 carbon atoms for each sulfonate group, and may contain a hetero atom.) A sulfonic acid ester group-containing polymer obtained by polymerization using the aromatic sulfonic acid ester derivative according to claim 1 or 2. A sulfonate group-containing polymer comprising a structural unit represented by the following general formula (P1).

(In formula (P1), each R independently represents a hydrocarbon group having 1 to 20 carbon atoms for each sulfonate group and may contain a hetero atom.) The sulfonate group-containing polymer according to claim 4, wherein the content of the structural unit represented by the general formula (P1) is 20% by weight or more. 5. The copolymer has a segment (A1) having at least a structural unit represented by the general formula (P1) and a segment (A2) having a structural unit not containing an ionic group, and the copolymerization mode is block copolymerization. Or a sulfonate group-containing polymer according to 5; The sulfonate group-containing polymer according to claim 6, wherein the structural unit not containing the ionic group is represented by the following general formula (P2).

(In the general formula (P2), Ar ^{1 to} Ar ⁴ represent an arbitrary divalent arylene group and may be optionally substituted, but do not contain an ionic group. Ar ^{1 to} Ar ⁴ are independent of each other. Two or more types of arylene groups may be used, and * represents a bonding site with the general formula (P2) or other structural unit.) 8. The sulfonate group-containing polymer according to claim 7, wherein the structural unit represented by the general formula (P2) is represented by the following formula (P3).

A polymer electrolyte material obtained by deesterifying the sulfonate group-containing polymer according to any one of claims 3 to 8. A polymer electrolyte molded article obtained by molding the sulfonic acid ester group-containing polymer according to any one of claims 3 to 8, heat-treating in a state of a sulfonic acid ester group, and then deesterifying the polymer. The polymer electrolyte molded article according to claim 10, wherein the sulfonate group-containing polymer further has a protective group, and at least a part of the protective group is deprotected before the heat treatment. An electrolyte membrane with a catalyst layer, comprising the polymer electrolyte material according to claim 9 or the molded polymer electrolyte according to claim 10 or 11. A solid polymer fuel cell comprising the polymer electrolyte material according to claim 9 or the molded polymer electrolyte according to claim 10 or 11.