JP4956921B2 - Aromatic compounds having fluorene units and sulfonated polyarylenes - Google Patents

Description

  The present invention relates to an aromatic compound having a fluorene unit and a sulfonated polyarylene derived from the compound.

  Conventionally, an electrolyte is often used in a (water) solution (that is, an electrolytic solution). However, in recent years, there is an increasing tendency to replace this with a solid system. The first reason is, for example, the ease of processing when applied to the above-mentioned electric / electronic materials, and the second reason is the shift to light, thin, small, and power saving.

Conventionally, both proton-conducting materials made of inorganic substances and organic substances are known.
Examples of inorganic substances include those using uranyl phosphate, which is a hydrated compound, but proton conductive materials made of these inorganic compounds are poor in workability, and even when the electrode layers are joined, In many cases, the adhesion at the interface is not sufficient, and proton conductivity at such an interface is insufficient, resulting in a problem that power generation performance is degraded.

On the other hand, as organic substances, polymers belonging to so-called cation exchange resins, for example, sulfonated products of vinyl polymers such as polystyrene sulfonic acid, perfluoroalkyl sulfonic acid polymers represented by Nafion (trade name, manufactured by DuPont), perfluoro Examples include alkyl carboxylic acid polymers, and polymers using organic polymers such as polymers in which sulfonic acid groups or phosphoric acid groups are introduced into heat-resistant polymers such as polybenzimidazole and polyether ether ketone. (Non-patent document 1: Polymer Preprints, Japan, Vol. 42, No. 7, p. 2490-2492 (1993), Non-patent document 2: Polymer Preprints, Japan, Vol. 43, No. 3, p. 735- 736 (1994), Non-Patent Document 3: Polymer Preprints, Japan, Vol.42, No.3, p.730 (1993))
These organic polymers are usually used as a film-like proton conductive material. In addition, the organic polymer has an advantage different from that of an inorganic material in that a conductive film can be bonded on an electrode by utilizing the solubility in a solvent or thermoplasticity.

Furthermore, US Pat. No. 5,403,675 (Patent Document 1) proposes a solid polymer electrolyte made of sulfonated rigid polyphenylene. This polymer is mainly composed of a polymer (structure described in the column 9) obtained by polymerizing an aromatic compound comprising a phenylene chain, and this is reacted with a sulfonating agent to introduce a sulfonic acid group.
Polymer Preprints, Japan, Vol.42, No.7, p.2490 ~ 2492 (1993) Polymer Preprints, Japan, Vol.43, No.3, p.735〜736 (1994) Polymer Preprints, Japan, Vol.42, No.3, p.730 (1993) US Pat. No. 5,403,675

However, in many of these organic polymers, proton conductivity is not sufficient yet, proton conductivity decreases at durability and high temperature (100 ° C. or higher), and mechanical properties, particularly elastic modulus, are low. It is not possible to say that it is greatly reduced, highly dependent on humidity conditions, or sufficiently adherent to the electrode, or due to excessive swelling during operation due to the water-containing polymer structure. There was a problem that it led to a drop and collapse of the shape. Therefore, the organic polymers described in Non-Patent Documents 1 to 3 have various problems when applied to the above-mentioned electric / electronic materials.

  Furthermore, in Patent Document 1, although the proton conductivity is improved by increasing the amount of sulfonic acid groups introduced, the mechanical properties of the sulfonated polymer obtained at the same time, such as toughness such as elongation at break and bending resistance, There was a problem that hot water resistance was remarkably impaired.

  Therefore, an object of the present invention is to provide a sulfonated polymer having excellent hot water resistance even when the amount of sulfonic acid groups introduced is increased, and a solid polymer having high proton conductivity and excellent power generation performance comprising the sulfonated polymer. To provide an electrolyte.

  Under such circumstances, as a result of intensive studies to solve the above problems, combining an aromatic unit having a fluorene skeleton with a unit having a sulfonic acid group and forming a phenylene bond, It has been found that polyarylene having excellent hot water resistance can be obtained even when the amount of introduction is increased.

That is, according to the present invention, the above-mentioned problems can be solved by providing a sulfonated polyarylene comprising the following aromatic compound, a structural unit derived from the compound, and a structural unit having a sulfonic acid group. it can.
[1] An aromatic compound represented by the following general formula (1).

[In the formula, A independently represents —CO— or —SO ₂ —, B independently represents an oxygen atom or a sulfur atom, X represents a halogen atom other than fluorine, or —OSO ₂ CH ₃ , —OSO ₂ CF ₃ represents a group selected from ₃ , R ^{1 to} R ⁸ may be the same or different from each other, and each represents a hydrogen atom, a fluorine atom, an alkyl group, a phenyl group or a nitrile group, and R ^{9 to} R ²⁴ are the same or different from each other. And represents a hydrogen atom, an alkyl group, or a phenyl group, and a represents 0 or an integer of 1 to 4. ]
[2] An aromatic compound in which the aromatic compound represented by the general formula (1) is represented by the following general formula (1a).

[Wherein, X represents a halogen atom excluding fluorine, or an atom or group selected from —OSO ₂ CH ₃ , —OSO ₂ CF ₃ , and R ⁹ and R ¹⁴ may be the same or different from each other, Represents an alkyl group or a phenyl group. ]
[3] A polymer containing a structural unit represented by the following general formula (1 ′).

[Wherein, A independently represents either —CO— or —SO ₂ —, B independently represents an oxygen atom or a sulfur atom, and R ^{1 to} R ²⁴ may be the same or different from each other, An atom, a fluorine atom, an alkyl group, a phenyl group or a nitrile group; a represents 0 or an integer of 1 to 4; ]
[4] A polyarylene polymer having a structural unit represented by the general formula (1 ′) and a structural unit represented by the following general formula (2).

[Wherein Y represents —CO—, —SO ₂ —, —SO—, —CONH—, —COO—, — (CF ₂ ) _l
- (l is an integer of 1 to _{10), - C (CF 3)} 2 - represents at least one structure selected from the group consisting of, Z is a direct bond _{or, - (CH 2) l -} ( l is an integer of 1 to 10), at least one structure selected from the group consisting of —C (CH ₃ ) ₂ —, —O—, and —S—, and Ar represents —SO ₃ H or — An aromatic group having a substituent represented by O (CH ₂ ) _p SO ₃ H or —O (CF ₂ ) _p SO ₃ H is shown. p shows the integer of 1-12, m shows the integer of 0-10, n shows the integer of 0-10, k shows the integer of 1-4. ]
[5] The polymer, wherein the structural unit represented by the general formula (1 ′) is represented by the following general formula (1′a).

[Wherein, R ⁹ and R ¹⁴ may be the same or different and each represents a hydrogen atom, an alkyl group, or a phenyl group. ]
[6] A proton conducting membrane comprising the polymer according to [4] or [5].
[7] The proton conducting membrane according to [6], wherein the structural unit represented by the general formula (1 ′) is composed of the general formula (1a ′).

  According to the present invention, an aromatic compound having a fluorene skeleton, an aromatic unit having a fluorene skeleton derived from the compound, and a copolymer having a sulfonic acid group and a unit forming a phenylene bond are provided. Is done. Such a polymer is highly resistant to hot water and can increase the concentration of sulfonic acid, so it has high proton conductivity and excellent mechanical properties, so that it is a solid polymer electrolyte (proton conducting membrane) with excellent power generation performance. ) Can be provided.

Hereinafter, the aromatic compound, polymer, and polyarylene polymer having a sulfonic acid group of the present invention will be described in detail.
[Aromatic compounds]
The aromatic compound according to the present invention is represented by the following general formula (1). Such a compound imparts hydrophobicity to a copolymer containing a unit derived from such a compound as a structural unit, and since the structural unit itself has a flexible structure, the toughness of the polymer and other mechanical strengths It has the effect of improving. Further, even if the amount of sulfonic acid groups introduced into other units constituting the copolymer is increased, the hydrophobicity is high, so that excellent hot water resistance is exhibited.

In the formula, A independently represents —CO— or —SO ₂ —. Among these, -CO- is preferable.
B independently represents an oxygen atom or a sulfur atom.

X represents a halogen atom excluding fluorine (chlorine, bromine, iodine), or an atom or group selected from —OSO ₂ CH ₃ and —OSO ₂ CF ₃ .
R ^{1 to} R ⁸ may be the same or different and each represents a hydrogen atom, a fluorine atom, an alkyl group, a phenyl group or a nitrile group, and R ^{9 to} R ²⁴ may be the same or different from each other, An alkyl group and a phenyl group are shown. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, an amyl group, and a hexyl group.

a is 0 or an integer of 1 to 4.
In particular, the aromatic compound represented by the following formula (1a) is preferable in terms of the toughness of the polymer and other mechanical strengths when a proton conducting membrane is produced.

[Wherein, X represents a halogen atom excluding fluorine, or an atom or group selected from —OSO ₂ CH ₃ , —OSO ₂ CF ₃ , and R ⁹ and R ¹⁴ may be the same or different from each other, Represents an alkyl group or a phenyl group. ]
Specific examples of the aromatic compound represented by the general formula (1) include the following.

The compound represented by the general formula (1) can be synthesized, for example, by the following reaction.
First, in order to convert a bisphenol having a fluorene skeleton into a corresponding alkali metal salt of bisphenol, in a polar solvent such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, sulfolane, diphenylsulfone, dimethylsulfoxide, Add alkali metals such as lithium, sodium and potassium, alkali metal hydrides, alkali metal carbonates and the like. The alkali metal is reacted in excess with respect to the hydroxyl group of phenol, and is usually used in an amount of 1.1 to 2 equivalents, preferably 1.2 to 1.5 equivalents. At this time, it is preferable to promote the progress of the reaction by coexisting a solvent azeotropic with water such as benzene, toluene, xylene, chlorobenzene, and anisole.

Examples of the bisphenol having a fluorene skeleton include 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, and 9,9-bis (4 -Hydroxy-3-phenylphenyl) fluorene, 9,9-bis (4-hydroxy-2-methylphenyl) fluorene, 9,9-bis (4-hydroxy-2-phenylphenyl) fluorene, 9,9-bis ( 4-hydroxy-2,5-dimethylphenyl) fluorene, 9,9-bis (4-hydroxy-3,5-dimethylphenyl) fluorene, 9,9-bis (4-hydroxy-3,5-diphenylphenyl) fluorene 9,9-bis (4-hydroxy-3-fluorophenyl) fluorene, 9,9-bis (4-hydroxy- -Cyclohexylphenyl) fluorene, 9,9-bis (4-hydroxy-3-ethylphenyl) fluorene, 9,9-bis (4-hydroxy-3-propylphenyl) fluorene, 9,9-bis (4-hydroxy- 3-isopropylphenyl) fluorene, 9,9-bis (4-hydroxy-3-butylphenyl) fluorene, 9,9-bis (4-hydroxy-3-tert-butylphenyl) fluorene, 9,9-bis (4 -Hydroxy-3-isobutylphenyl) fluorene and the like.

Next, the alkali metal salt of bisphenol and a specific dihalogenated aromatic compound are reacted. In this reaction, the alkali metal and the halogen are eliminated as a salt, and the bisphenol ring and the dihalogenated aromatic compound are bonded via —O—. In addition, when bisthiophenol is used instead of bisphenol and the same reaction is carried out, the bisthiophenol ring and the dihalogenated aromatic compound are bonded via -S-.

  Examples of the dihalogenated aromatic compound to be reacted include bis (4-chlorophenyl) sulfone, bis (3-chlorophenyl) sulfone, bis (2-chlorophenyl) sulfone, 3-chlorophenyl-4-chlorophenylsulfone, and 2-chlorophenyl-4. -Chlorophenylsulfone, 4-chlorophenyl-4-fluorophenylsulfone, 2-chlorophenyl-4-fluorophenylsulfone, 3-chlorophenyl-4-fluorophenylsulfone, 4-chlorophenyl-2-fluorophenylsulfone, 4-chlorophenyl-3- Examples include sulfones such as fluorophenylsulfone, 1,4-bis (4-chlorosulfonyl) benzene, 1,3-bis (4-chlorosulfonyl) benzene, and 1,2-bis (4-chlorosulfonyl) benzene. That.

Furthermore, 4,4′-dichlorobenzophenone, 3,3′-dichlorobenzophenone, 2,2′-dichlorobenzophenone, 3,4′-dichlorobenzophenone, 2,4′-dichlorobenzophenone, 4-chloro-4′-fluoro Benzophenone, 2-chloro-4'-fluorobenzophenone, 3-chloro-4'-fluorobenzophenone, 4-chloro-2'-fluorobenzophenone, 4-chloro-3'-fluorobenzophenone, 1,4-bis (4- Chlorobenzoyl) benzene, 1,3-bis (4-chlorobenzoyl) benzene, 1,2-bis (4-chlorobenzoyl) benzene, 1,4-bis (3-chlorobenzoyl) benzene, 1,3-bis ( 3-chlorobenzoyl) benzene, 1,2-bis (3-chlorobenzoyl) benzene, 1,4-bis (2 Chlorobenzoyl) benzene, 1,3-bis (2-chlorobenzoyl) benzene, 1,2-bis (2-chlorobenzoyl) benzene, 1,4-bis (4-chlorobenzoyl) -2,3,5,6 And benzophenones such as tetrafluorobenzene and 1,3-bis (4-chlorobenzoyl) -2,4,5,6-tetrafluorobenzene.

  Furthermore, 2,6-dichlorobenzonitrile, 2,5-dichlorobenzonitrile, 2,4-dichlorobenzonitrile, 2-chloro-6-fluorobenzonitrile, 2-chloro-5-fluorobenzonitrile, 2-chloro Benzonitriles such as -4-fluorobenzonitrile, 4-chloro-2-fluorobenzonitrile and 5-chloro-2-fluorobenzonitrile can be mentioned.

  Of these, 4,4′-dichlorobenzophenone, 3,4′-dichlorobenzophenone, 2,4′-dichlorobenzophenone, 4-chloro-4′-fluorobenzophenone, 2-chloro-4′-fluorobenzophenone, 4- Chloro-2'-fluorobenzophenone, 2,6-dichlorobenzonitrile, 2,5-dichlorobenzonitrile and 2,4-dichlorobenzonitrile are preferred.

The dihalogenated aromatic compound is used in an amount of 2.0 times mol or more, preferably 2.1 to 5 times mol with respect to bisphenol. Thus, the aromatic compound having the structure represented by the general formula (1) can be obtained by adding 2.0 times mole or more of the dihalogenated aromatic compound to the bisphenol.

The reaction is carried out at a reaction temperature of 60 ° C to 300 ° C, preferably in the range of 80 ° C to 250 ° C, and in a reaction time of 15 minutes to 100 hours, preferably in the range of 1 hour to 24 hours.
When a compound having a chloro group and a fluoro group is used as the dihalogenated aromatic compound, the conditions for allowing only the fluoro group to react with bisphenol are set by adjusting the charging ratio, reaction temperature, and reaction time.

The obtained reaction product can be purified by a method such as reprecipitation or recrystallization.
The progress of the above reaction and the produced aromatic compound are identified by a known method. For example, it is identified by NMR, IR or the like.

In IR spectrum disappeared absorption derived from a phenolic hydroxyl group in the vicinity 3650~3584cm ^-1, 1275~1200cm ^-1 and around, by absorption derived from an ether bond at around 1075～1020Cm ^-1 becomes remarkable I can confirm. In NMR spectrum, it can confirm by the loss | disappearance of the signal originating in the hydrogen atom of the phenol hydroxyl group of 11-9 ppm vicinity.
[Polyarylene polymer]
The polyarylene polymer according to the present invention may be a homopolymer composed only of a structural unit represented by the following general formula (1 ′) derived from the above formula (1), or may be a structural unit (1 ′ ) And other structural units.

In the formula, A independently represents either —CO— or —SO ₂ —.
B independently represents an oxygen atom or a sulfur atom.
R ^{1 to} R ⁸ may be the same or different and each represents a hydrogen atom, a fluorine atom, an alkyl group, a phenyl group or a nitrile group, and R ^{9 to} R ²⁴ may be the same or different from each other, An alkyl group and a phenyl group are shown.

a represents 0 or an integer of 1 to 4.
Among the structural units represented by the above formula (1 ′), those represented by the following formula (1′a) are preferable in terms of ease of production together with toughness and mechanical strength.

[Wherein, X represents a halogen atom excluding fluorine, or an atom or group selected from —OSO ₂ CH ₃ , —OSO ₂ CF ₃ , and R ⁹ and R ¹⁴ may be the same or different from each other, Represents an alkyl group or a phenyl group. ]
As a structural unit other than the structural unit (1 ′) constituting the polyarylene polymer of the present invention, a structural unit represented by the following general formula (2) is preferable. Those having such a structural unit have high proton conductivity and are suitable as a proton conducting membrane.

In the general formula (2), Y represents —CO—, —SO ₂ —, —SO—, —CONH—, —CO.
It represents at least one structure selected from the group consisting of O—, — (CF ₂ ) ₁ — (l is an integer of 1 to 10), and —C (CF ₃ ) ₂ —. Of these, —CO— and —SO ₂ — are preferable.

Z is a direct bond or at least one selected from the group consisting of — (CH ₂ ) ₁ — (wherein 1 is an integer of 1 to 10), —C (CH ₃ ) ₂ —, —O—, and —S—. The structure of the species is shown. Among these, a direct bond and -O- are preferable.

Ar is an aromatic group having a substituent represented by —SO ₃ H or —O (CH ₂ ) _p SO ₃ H or —O (CF ₂ ) _p SO ₃ H (p represents an integer of 1 to 12). Indicates.
Specific examples of the aromatic group include a phenyl group, a naphthyl group, an anthryl group, and a phenanthryl group. Of these groups, a phenyl group and a naphthyl group are preferable. -SO ₃
At least one substituent represented by H or —O (CH ₂ ) _p SO ₃ H or —O (CF ₂ ) _p SO ₃ H (p represents an integer of 1 to 12) is substituted. In the case of a naphthyl group, it is preferable that two or more are substituted.

m is an integer of 0 to 10, preferably 0 to 2, n is an integer of 0 to 10, preferably 0 to 2, and k is an integer of 1 to 4.
As a preferable combination of the values of m and n and the structures of Y, Z and Ar,
(1) a structure in which m = 0, n = 0, Y is —CO—, and Ar is a phenyl group having —SO ₃ H as a substituent;
(2) a structure in which m = 1, n = 0, Y is —CO—, Z is —O—, and Ar is a phenyl group having —SO ₃ H as a substituent;
(3) a structure in which m = 1, n = 1, k = 1, Y is —CO—, Z is —O—, and Ar is a phenyl group having —SO ₃ H as a substituent;
(4) a m = 1, n = 0, Y is -CO-, 2 pieces of -SO ₃ as Ar is a substituted group
A structure which is a naphthyl group having H,
(5) m = 1, n = 0, Y is —CO—, Z is —O—, and Ar is a phenyl group having —O (CH ₂ ) ₄ SO ₃ H as a substituent. Examples include structures.

In order to increase proton conductivity, the amount of —SO ₃ H contained in the structural unit of the formula (2) may be increased, or the proportion of the structural unit in the formula (2) may be increased.
<Method for producing polymer>
For the production of a polyarylene having a sulfonic acid group composed of structural units of the formulas (1 ′) and (2), for example, the following three methods, Method A, Method B and Method C, are used. Can do.
(Method A)
For example, in the method described in JP-A No. 2004-137444, a monomer having a sulfonate group that can be a structural unit represented by the general formula (2), and a monomer represented by the general formula (1) To produce a polyarylene having a sulfonic acid ester group, deesterifying the sulfonic acid ester group, and converting the sulfonic acid ester group to a sulfonic acid group to synthesize a polyarylene having a sulfonic acid group. To do.
(Method B)
For example, in the method described in JP-A-2001-342241, a monomer having a skeleton represented by the above general formula (2) but not having a sulfonic acid group or a sulfonic acid ester group, and the above general formula (1) And a polyarylene having a sulfonic acid group is synthesized by sulfonating the polymer with a sulfonating agent.
(Method C)
In the general formula (2), when Ar is an aromatic group having a substituent represented by —O (CH ₂ ) _p SO ₃ H or —O (CF ₂ ) _p SO ₃ H, for example, The precursor monomer that can be the structural unit represented by the general formula (2) and the monomer represented by the general formula (1) are copolymerized by the method described in Japanese Patent Application No. 2003-295974, It can also be synthesized by a method of introducing alkylsulfonic acid or fluorine-substituted alkylsulfonic acid.

  Specific examples of the monomer having a sulfonic acid ester group that can be used in (Method A) and can be the structural unit represented by the above general formula (2) are disclosed in JP-A Nos. 2004-137444 and 2004-2004. Examples thereof include aromatic sulfonic acid esters described in Japanese Patent No. 345997 and Japanese Patent Application Laid-Open No. 2004-346163.

  As a specific example of a monomer that can be used in (Method B) and can be a structural unit represented by the above general formula (2) but does not have a sulfonic acid group or a sulfonic acid ester group, JP-A-2001-2001 Examples thereof include dihalides described in Japanese Patent No. 342241 and Japanese Patent Application Laid-Open No. 2002-238889.

  Specific examples of precursor monomers that can be used in (Method C) and can be structural units represented by the above general formula (2) include dihalides described in Japanese Patent Application No. 2003-275409. be able to. Specifically, 2,5-dichloro-4′-hydroxybenzophenone, 2,4-dichloro-4′-hydroxybenzophenone, 2,6-dichloro-4′-hydroxybenzophenone, 2,5-dichloro-2 ′, Examples thereof include 4′-dihydroxybenzophenone and 2,4-dichloro-2 ′, 4′-dihydroxybenzophenone. Moreover, the compound which protected the hydroxyl group of these compounds by the tetrahydropyranyl group etc. can be mention | raise | lifted. Moreover, the thing which the hydroxyl group replaced with the thiol group, and the chlorine atom replaced with the bromine atom and the iodine atom can also be mentioned.

  Specific examples of these catalyst components, the use ratio of each component, the polymerization conditions such as the reaction solvent, concentration, temperature, time, etc. include the compounds described in JP-A No. 2001-342241.

For example, as the transition metal salt, nickel chloride, nickel bromide and the like are preferably used,
Moreover, as a compound used as a ligand, triphenylphosphine and 2,2'-bipyridine are preferably used. Furthermore, nickel chloride bis (triphenylphosphine) and nickel chloride (2,2′bipyridine) are preferably used as the transition metal (salt) in which the ligand is coordinated in advance. Examples of the reducing agent include iron, zinc, manganese, aluminum, magnesium, sodium, and calcium, and zinc, magnesium, and manganese are preferable. As the “salt”, sodium bromide, sodium iodide, potassium bromide, tetraethylammonium bromide, and tetraethylammonium iodide are preferable. A polymerization solvent may be used for the reaction, and specifically, tetrahydrofuran, N, N-dimethylformamide, N, N-dimethylacetamide, 1-methyl-2-pyrrolidone and the like are preferably used.

  The polyarylene having a sulfonic acid group of the present invention can be obtained by converting the precursor polyarylene into a polyarylene having a sulfonic acid group. As this method, there are the following three methods.

In the case of (Method A), the sulfonate group in the precursor polyarylene is deesterified by the method described in JP-A-2004-137444.
In the case of (Method B), a sulfonic acid group is introduced into the precursor polyarylene according to a known method such as JP-A-2001-342241.

  In the case of (Method C), a method of introducing an alkylsulfonic acid group into the precursor polyarylene by the method described in Japanese Patent Application No. 2003-295974. In the method C, for example, it can be introduced by reacting the hydroxyl group of the precursor polyarylene with propane sultone, butane sultone, or the like.

  The ion exchange capacity of the polyarylene having a sulfonic acid group produced by the method as described above is usually 0.3 to 5 meq / g, preferably 0.5 to 3 meq / g, more preferably 0.8 to 2. 0.8 meq / g. If it is less than 0.3 meq / g, the proton conductivity is low and the power generation performance is low. On the other hand, if it exceeds 5 meq / g, the water resistance may be significantly lowered.

The polyarylene for proton conducting membrane of the present invention has a structural unit represented by the formula (1 ′), and therefore has a flexible structure, so that the toughness of the polymer and other mechanical strengths are improved. Have the effect of Further, even if the amount of sulfonic acid groups introduced is increased in order to increase the ion exchange capacity, the water resistance is not lowered because the hydrophobicity is high.

  The ion exchange capacity is, for example, a precursor monomer that can be a structural unit represented by the general formula (2), the type and use ratio of the monomer represented by the general formula (1), and a sulfonic acid group to be introduced. It can be adjusted by changing the amount and combination of the above.

The molecular weight of the polyarylene having a sulfonic acid group thus obtained is 10,000 to 1,000,000, preferably 20,000 to 800,000 in terms of polystyrene-equivalent weight average molecular weight by gel permeation chromatography (GPC).
<Proton conducting membrane and production method thereof>
Among such polymers according to the present invention, in particular, a copolymer having a sulfonic acid group (specifically, one containing structural units (1 ′) and (2)) is a proton conducting membrane (solid polymer). It is preferably used as an electrolyte. The proton conducting membrane is formed by a method (solvent casting method) or the like by casting a composition obtained by dissolving the copolymer and, if necessary, an additive in an organic solvent on a base material, and forming the film into a film. Is done.

The base material is not particularly limited as long as it is a base material used in a normal solution casting method, and a base material made of plastic, metal, or the like is used, and further, it is made of a thermoplastic resin such as a polyethylene terephthalate (PET) film. A substrate is used.

The solution viscosity depends on the molecular weight of the polymer and the polymer concentration.
The range may be 100,000 mPa · s, preferably 3,000 to 50,000 mPa · s.

  Specific examples of the solvent used in the film forming method include N-methyl-2-pyrrolidone, N, N-dimethylformamide, γ-butyrolactone, N, N-dimethylacetamide, dimethyl sulfoxide, dimethylurea, and dimethylimidazo. Examples include aprotic polar solvents such as lysinone. Among these, N-methyl-2-pyrrolidone (hereinafter also referred to as “NMP”) is particularly preferable in terms of solubility and solution viscosity. The aprotic polar solvents may be used singly or in combination of two or more.

  Further, as the solvent, a mixture of the aprotic polar solvent and alcohol may be used. Examples of such alcohol include methanol, ethanol, propyl alcohol, iso-propyl alcohol, sec-butyl alcohol, tert-butyl alcohol, and the like. Among these, methanol is particularly preferable because it has an effect of lowering the solution viscosity in a wide composition range. Alcohol may be used individually by 1 type, or may be used in combination of 2 or more type.

In addition to the alcohol, an inorganic acid such as sulfuric acid or phosphoric acid, an organic acid containing a carboxylic acid, an appropriate amount of water, or the like may be used in combination.
The polymer concentration of the solution during film formation is usually 5 to 40% by weight, preferably 7 to 25% by weight. If the polymer concentration is less than 5% by weight, it is difficult to form a thick film, and pinholes tend to be generated. On the other hand, when the polymer concentration exceeds 40% by weight, the solution viscosity is so high that it is difficult to form a film, and surface smoothness may be lacking.

The solution viscosity is usually 2,000 to 100,000 mPa · s, preferably 3,000.
˜50,000 mPa · s. When the solution viscosity is less than 2,000 mPa · s, the retention of the solution during film formation is poor and the solution may flow from the substrate. On the other hand, the solution viscosity is 100,000
If it exceeds mPa · s, the viscosity is too high, so extrusion from the die cannot be performed, and film formation by the casting method may be difficult.

  After film formation as described above, when the obtained undried film is immersed in water, the organic solvent in the undried film can be replaced with water, and the residual solvent amount of the resulting proton conducting membrane is reduced. be able to. In addition, you may predry an undried film before immersing an undried film in water. The preliminary drying is performed by holding the undried film at a temperature of usually 50 to 150 ° C. for 0.1 to 10 hours.

  When immersing an undried film (including a pre-dried film; the same applies hereinafter) in water, a batch method in which a single wafer is immersed in water may be used, and the film is formed on a substrate film (for example, PET). A continuous system may be used in which the laminated film is left as it is, or the film separated from the substrate is immersed in water and wound up. Moreover, in the case of a batch system, in order to suppress the formation of wrinkles on the treated film surface, it is preferable to immerse the film in water by a method such as placing an undried film on a frame.

The amount of water used in immersing the undried film in water is 10 parts by weight or more, preferably 30 parts by weight or more, more preferably 50 parts by weight or more with respect to 1 part by weight of the undried film. If the amount of water used is in the above range, the amount of residual solvent in the resulting proton conducting membrane can be reduced. In addition, the water used for the immersion is changed or overflowed, so that the organic solvent concentration in the water is always kept at a certain level or less to reduce the residual solvent amount of the obtained proton conducting membrane. It is valid. Furthermore, in order to suppress the in-plane distribution of the amount of the organic solvent remaining in the proton conductive membrane, it is effective to homogenize the concentration of the organic solvent in water by stirring or the like.

  The temperature of water when the undried film is immersed in water is usually in the range of 5 to 80 ° C., preferably 10 to 60 ° C., from the viewpoint of the replacement speed and ease of handling. The higher the temperature, the faster the replacement rate between the organic solvent and water, but the greater the amount of water absorbed by the film, so the surface state of the proton conducting membrane obtained after drying may deteriorate. Further, the immersion time of the film is usually in the range of 10 minutes to 240 hours, preferably 30 minutes to 100 hours, although it depends on the initial residual solvent amount, the amount of water used and the treatment temperature.

  After immersing the undried film in water as described above, the film is dried at 30-100 ° C, preferably 50-80 ° C, for 10-180 minutes, preferably 15-60 minutes, and then at 50-150 ° C. The proton conducting membrane can be obtained by vacuum drying under reduced pressure of 500 mmHg to 0.1 mmHg for 0.5 to 24 hours.

The residual solvent amount of the proton conducting membrane obtained as described above is usually reduced to 5% by weight or less, preferably 1% by weight or less.
The proton conductive membrane obtained has a dry film thickness of usually 10 to 100 μm, preferably 20 to 80 μm, and this thickness can be controlled by adjusting the thickness of the base material (frame shape).
[Example]
EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples. The various measurement items in the examples were determined as follows.
(Molecular weight)
As for the molecular weight of the polymer, a polystyrene-reduced weight average molecular weight was determined by GPC. N-methyl-2-pyrrolidone to which lithium bromide was added was used as a solvent.
(Ion exchange capacity)
The obtained sulfonated polymer is washed until the washing water has a pH of 4 to 6, the free remaining acid is removed, washed thoroughly, dried, weighed, and mixed with THF / water. After dissolving in a solvent, phenolphthalein was used as an indicator, titration was performed with a standard solution of NaOH, and the ion exchange capacity was determined from the neutralization point.
Example 1
To a 1 L three-necked flask equipped with a stirrer, thermometer, Dean-stark tube, nitrogen introduction tube, and cooling tube, 9,9-bisphenolfluorene 20.0 g (57 mmol), 2,4′-dichlorobenzophenone 43.1 g (171 mmol) ) And 10.3 g (74 mmol) of potassium carbonate were weighed. After nitrogen substitution, 243 ml of sulfolane and 121 ml of toluene were added and stirred. The reaction solution was heated to reflux at 130 ° 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 15 hours. Then, 43.1 g (171 mmol) of 2,4′-dichlorobenzophenone was added, and the reaction was further continued for 8 hours.

The reaction solution was allowed to cool, and diluted with 100 ml of toluene. Inorganic salts insoluble in the reaction solution were 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 41 g of the desired product. The resulting compound has the formula [1]
It confirmed that it was a compound represented by these.

Example 2
In Example 1, 2,0.0 g (57 mmol) of 9,9-bisphenolfluorene was converted to 21.6 g (57 mmol) of 9,9-biscresol fluorene, and 43.1 g (171 mmol) of 2,4′-dichlorobenzophenone was 4,4 ′. -The reaction was carried out in the same manner except for changing to 43.1 g (171 mmol) of dichlorobenzophenone to obtain 44 g of the desired product. It was confirmed that the obtained compound was a compound represented by the formula [2].

Example 3
In Example 1, 9,9-bisphenolfluorene (20.0 g, 57 mmol) was replaced with 9,9-bis (2-phenylphenol) fluorene (28.7 g, 57 mmol) and 2,4′-dichlorobenzophenone (43.1 g, 171 mmol). The reaction was conducted in the same manner except that 40.2 g (171 mmol) of 4-chloro-4′-fluorobenzophenone was changed to obtain 51 g of the desired product. It was confirmed that the obtained compound was a compound represented by the formula [3].

Example 4
In a 3 L three-necked flask equipped with a stirrer, a thermometer, and a nitrogen inlet tube, 97.5 g (125 mmol) of the compound represented by the formula [1] obtained in Example 1 and 3- (2,5-dichlorobenzoyl) Neopentyl benzenesulfonate 150.5 g (375 mmol), bis (triphenylphosphine) nickel dichloride 9.81 g (15 mmol), sodium iodide 2.3 g (15 mmol), triphenylphosphine 52.5 g (200 mmol), zinc 78.4 g (1200 mmol) was weighed and replaced with dry nitrogen. N, N-dimethylacetamide (DMAc) (580 mL) was added thereto, and stirring was continued for 3 hours while maintaining the reaction temperature at 80 ° C., and then DMAc (600 mL) was added to dilute, and insoluble matters were filtered.

The obtained filtrate was put into a 3 L three-necked flask equipped with a stirrer, a thermometer, and a nitrogen introduction tube, and heated and stirred at 115 ° C., and 71.7 g (830 mmol) of lithium bromide was added. After stirring for 7 hours, the product was precipitated by pouring into 5 L of acetone. Next, after washing with 1N hydrochloric acid and pure water in this order, drying was performed to obtain 178 g of the target sulfonated polymer. The weight average molecular weight of the obtained polymer was 80,000. The obtained polymer is presumed to be a sulfonated polymer represented by the formula [4]. The ion exchange capacity of this polymer was 1.9 meq / g.

This polymer was dissolved in N-methylpyrrolidone, and a film having a thickness of 50 μm was prepared by a casting method. When the obtained film was immersed in hot water at 120 ° C. for 24 hours, the form of the film was maintained.
Example 5
In Example 4, 97.5 g (125 mmol) of the compound represented by the formula [1] obtained in Example 1 was replaced with 101.0 g (125 mmol) of the compound represented by the formula [2] obtained in Example 2. The reaction was conducted in the same manner as in Example 4 except that 177 g of the target sulfonated polymer was obtained. The weight average molecular weight of the obtained polymer was 76,000. The obtained polymer is presumed to be a sulfonated polymer represented by the formula [5]. The ion exchange capacity of this polymer was 1.9 meq / g.

This polymer was dissolved in N-methylpyrrolidone, and a film having a thickness of 50 μm was prepared by a casting method. When the obtained film was immersed in hot water at 120 ° C. for 24 hours, the form of the film was maintained.
Example 6
In Example 4, 97.5 g (125 mmol) of the compound represented by the formula [1] obtained in Example 1 was replaced with 116.5 g (125 mmol) of the compound represented by the formula [3] obtained in Example 3. The reaction was carried out in the same manner as in Example 4 except that 197 g of the target sulfonated polymer was obtained. The weight average molecular weight of the obtained polymer was 83,000. The obtained polymer is presumed to be a sulfonated polymer represented by the formula [6]. The ion exchange capacity of this polymer was 1.8 meq / g.

This polymer was dissolved in N-methylpyrrolidone, and a film having a thickness of 50 μm was prepared by a casting method. When the obtained film was immersed in hot water at 120 ° C. for 24 hours, the form of the film was maintained.
Comparative Example 1
The same reaction was carried out except that 20.0 g (57 mmol) of 9,9-bisphenolfluorene in Example 1 was replaced with 11.4 g (57 mmol) of bis (4-hydroxyphenyl) methane, to obtain 32 g of the desired product. . It was confirmed that the obtained compound was a compound represented by the formula [7].

  Next, instead of 97.5 g (125 mmol) of the compound represented by the formula [1] in Example 4, 78.7 g (125 mmol) of the compound represented by the above formula [7] was used. The same reaction as in Example 4 was performed to obtain 161 g of a sulfonated polymer. The weight average molecular weight of the obtained polymer was 74,000. The obtained polymer is presumed to be a sulfonated polymer represented by the formula [8]. The ion exchange capacity of this polymer was 1.9 meq / g.

  This polymer was dissolved in N-methylpyrrolidone, and a film having a thickness of 50 μm was prepared by a casting method. When the obtained film was immersed in hot water at 120 ° C. for 24 hours, the film was significantly swollen and the initial shape could not be maintained.

  In view of the above, the copolymer of the present invention having an aromatic unit having a fluorene skeleton and a unit having a sulfonic acid group and forming a phenylene bond can be used in hot water even with an equivalent ion exchange capacity. It can be seen that the resistance to is extremely excellent.

Claims (7)

An aromatic compound represented by the following general formula (1).

[In the formula, A independently represents —CO— or —SO ₂ —, B independently represents an oxygen atom or a sulfur atom, X represents a halogen atom other than fluorine, or —OSO ₂ CH ₃ , —OSO ₂ CF ₃ represents a group selected from ₃ , R ^{1 to} R ⁸ may be the same or different from each other, and each represents a hydrogen atom, a fluorine atom, an alkyl group, a phenyl group or a nitrile group, and R ^{9 to} R ²⁴ are the same or different from each other. And represents a hydrogen atom, an alkyl group, or a phenyl group, and a represents 0 or an integer of 1 to 4. ] The aromatic compound according to claim 1, wherein the aromatic compound represented by the general formula (1) is represented by the following general formula (1a).

[Wherein, X represents a halogen atom excluding fluorine, or an atom or group selected from —OSO ₂ CH ₃ , —OSO ₂ CF ₃ , and R ⁹ and R ¹⁴ may be the same or different from each other, Represents an alkyl group or a phenyl group. ] A polyarylene polymer comprising a structural unit represented by the following general formula (1 ′) and a structural unit having a sulfonic acid group and forming a phenylene bond.

[Wherein, A independently represents either —CO— or —SO ₂ —, B independently represents an oxygen atom or a sulfur atom, and R ^{1 to} R ⁸ may be the same or different from each other, An atom, a fluorine atom, an alkyl group, a phenyl group or a nitrile group; R ^{9 to} R ²⁴ may be the same or different from each other; a hydrogen atom, an alkyl group or a phenyl group; a is 0 or 1 to 4 Indicates an integer. ] A polyarylene polymer having a structural unit represented by the following general formula (1 ′) and a structural unit represented by the following general formula (2).

[ Wherein , A independently represents either —CO— or —SO ₂ —, B independently represents an oxygen atom or a sulfur atom, and R ^{1 to} R ⁸ may be the same or different from each other, An atom, a fluorine atom, an alkyl group, a phenyl group or a nitrile group; R ^{9 to} R ²⁴ may be the same or different from each other; a hydrogen atom, an alkyl group or a phenyl group; a is 0 or 1 to 4 Indicates an integer. Further, Y is _{-CO -, - SO 2 -,} - SO -, - CONH -, - COO -, - (CF 2) l - (l is an integer of 1 to 10), - C (CF _{3) 2} represents at least one structure selected from the group consisting of —, Z is a direct bond, or — (CH ₂ ) ₁ — (l is an integer of 1 to 10), —C (CH ₃ ) ₂ — , -O -, - represents at least one structure selected from the group consisting of S-, Ar is -SO ₃ H or _{-O (CH 2) p SO 3} H or -O (CF _{2) p} SO ₃ An aromatic group having a substituent represented by H is shown. p shows the integer of 1-12, m shows the integer of 0-10, n shows the integer of 0-10, k shows the integer of 1-4. ] The polyarylene polymer according to claim 3 or 4, wherein the structural unit represented by the general formula (1 ') is represented by the following general formula (1'a).

[Wherein R ⁹ and R ¹⁴ may be the same or different from each other, and each represents a hydrogen atom, a fluorine atom, an alkyl group or a phenyl group. ]   A proton conducting membrane comprising the polyarylene polymer according to any one of claims 3 to 5.   The proton conducting membrane according to claim 6, wherein the structural unit represented by the general formula (1 ') is composed of the general formula (1a').