JP2011132388A - Method for producing polymer electrolyte membrane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a polymer electrolyte material and a polymer electrolyte membrane having excellent proton conductivity under low humidification conditions and capable of achieving long-term power generation durability when used in a solid polymer type fuel cell. <P>SOLUTION: The method for producing the polymer electrolyte membrane obtained by the desalting polycondensation of a diol monomer containing a hydrolyzable group and an ionic group and a dihalide monomer includes the steps of: (1) heating a diol containing a hydrolyzable diol monomer and a dihalide monomer together with a basic compound to obtain an electrolyte prepolymer solution; (2) adding specific mol% amounts of a diol monomer containing an ionic group and a dihalide monomer containing an ionic group to the electrolyte prepolymer solution, followed by heating and dehydrating the mixture to obtain an electrolyte polymer solution; (3) subjecting the electrolyte polymer solution to solid-liquid separation to form a coating liquid; (4) applying the coating liquid on a substrate by casting to form a coating film; and (5) bringing the film-like material into contact with an acidic aqueous solution to form the polymer electrolyte membrane. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  INDUSTRIAL APPLICABILITY The present invention is a polymer electrolyte fuel cell that has excellent proton conductivity even under high-temperature and low-humidification conditions, and can achieve long-term durability when a solid polymer fuel cell is obtained. The present invention relates to a method for producing an excellent polymer electrolyte membrane.

  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 low standard operating temperature of 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.

  As polymer electrolyte materials, aromatic polyether ketones and aromatic polyether sulfones have been particularly actively studied from the viewpoints of heat resistance and chemical stability.

  In a sulfonated product (for example, Patent Documents 1 and 2) of an aromatic polyether ketone (hereinafter, sometimes abbreviated as PEK) (including Victrex PEEK-HT (manufactured by Victrex)), it is high. Due to crystallinity, polymers having a low sulfonic acid group density composition have the problem that crystals remain insoluble in the solvent and cause poor processability. Conversely, the sulfonic acid group density is increased to improve processability. When the polymer is no longer crystalline, it absorbs more water and swells significantly in water, resulting in not only a large fuel crossover in the polymer electrolyte membrane produced, but also fuel barrier properties, mechanical strength, hot water resistance, and heat resistance methanol resistance. The chemical stability was insufficient.

  As an invention for solving these problems, in Patent Document 3, a polymer having a crystallization ability in which a protective group (hydrolyzable solubility-imparting group) is introduced into a polymer electrolyte having an ionic group has been successfully made into a solution. , It is proposed to improve processability by a method of deprotection (hydrolysis), and even if the processability is improved, the proton conductivity is still excellent, and the fuel blocking property, mechanical strength, hot water resistance, heat resistant methanol property, The company says it can provide electrolyte membranes with excellent chemical stability.

  Patent Document 4 and Patent Document 5 disclose an electrolyte membrane comprising a block copolymer of a hydrophobic segment (nonionic region) and a hydrophilic segment (ionic region). Compared to random copolymers, proton conductivity is equivalent or better, less water absorption, excellent water resistance, and by increasing the number of hydrophilic segments introduced with sulfonic acid groups, proton conductivity can be improved. Are listed.

  Moreover, in patent document 6, in order to increase the introduction amount of a sulfonic acid group, a plurality of sulfonic acid groups are introduced into the side chain to increase the sulfonic acid group density of the hydrophilic segment (ionic group region). .

JP-A-6-93114 Japanese translation of PCT publication No. 2004-528683 JP 2006-261103 A Japanese Patent Laid-Open No. 2003-3232 Japanese translation of PCT publication No. 2006-512428 Special table 2007-210919

  In view of the background of such prior art, the present invention has a high proton conductivity in order to obtain excellent power generation characteristics even at a high temperature of 80 ° C. or higher and a relative humidity of 60% or less and a high humidity and low humidity. When the fuel cell is a type fuel cell, it has excellent practicality that can achieve excellent durability in a durability test (wet / dry cycle test) that repeats wetting of the polymer electrolyte membrane with power generation and drying in an open circuit state It is an object of the present invention to provide a method for producing a polymer electrolyte membrane.

  The present invention produces a high-quality, low-cost polymer electrolyte membrane with high proton conductivity and excellent durability balance in order to obtain high-output power generation characteristics under high temperature and low humidification conditions. In order to solve the problem, the following means are adopted.

That is, the present invention relates to a polymer electrolyte membrane having a precursor, which is a film-like product composed of a polymer containing a hydrolyzable group and an ionic group, which is obtained by desalting polycondensation of diol monomers and dihalide monomers. The manufacturing method is characterized by having the following steps.
(1) A diol monomer containing 20 to 100 mol% of a diol monomer having a hydrolyzable group and a dihalide monomer, the total content of the diol monomer having an ionic group and the dihalide monomer having an ionic group is 0 Step of obtaining an electrolyte prepolymer solution by dissolving in a solvent and bringing it into contact with a basic compound so as to be ˜20 mol% (2) A diol containing 10 mol% or more of a diol monomer having an ionic group A dihalide monomer containing 20 to 100 mol% of a monomer and a dihalide monomer having an ionic group, a total content of a diol monomer having an ionic group and a dihalide monomer having an ionic group is the step (1). Including the total of diol monomer having ionic group and dihalide monomer having ionic group Step (3) Step (2) to obtain an electrolyte polymer solution by adding to the electrolyte prepolymer solution obtained in the step (1) and dehydrating by heating so that the amount value is 10 to 100 mol%. The subsequent electrolyte polymer solution is subjected to solid-liquid separation by direct centrifugal separation to form a coating solution (4) The coating solution after the step (3) is cast-coated on a substrate, and the solvent is evaporated by heating. (5) The step of using the membrane as a precursor and bringing it into contact with an acidic aqueous solution to form a polymer electrolyte membrane

  The present invention relates to a method for producing a polymer electrolyte membrane using as a precursor a film-like product comprising a polymer containing a hydrolyzable group and an ionic group, which is obtained by desalting polycondensation of diol monomers and dihalide monomers. However, by using not only a dihalide monomer having an ionic group but also a diol monomer having an ionic group, the introduction amount of the ionic group is increased, and thus the ionic region in the block copolymer is increased. By increasing the concentration of the ionic group, high proton conductivity can be obtained, and at the same time, excellent compatibility with durability can be achieved.

  According to the present invention, a method for producing a polymer electrolyte membrane having both high proton conductivity and excellent durability can be provided, and in particular, a polymer electrolyte fuel cell using the polymer electrolyte membrane obtained by the present invention. Is a durability test in which high power generation characteristics can be obtained even under high temperature and low humidification conditions with a relative humidity of 60% or less at a high temperature of 80 ° C or higher, and the polymer electrolyte membrane with power generation is repeatedly wetted and dried in an open circuit state. Excellent durability in (wet and dry cycle test).

  Hereinafter, the present invention will be described in detail.

  The method for producing a polymer electrolyte membrane of the present invention uses a membrane-like product made of a polymer containing a hydrolyzable group and an ionic group, obtained by desalting polycondensation of diol monomers and dihalide monomers as a precursor. This is a method for producing a polymer electrolyte membrane.

  The polymer system applicable to the present invention is preferably a hydrocarbon-based polymer from the viewpoint of mechanical strength, physical durability, chemical stability, etc., and among them, a polymer having an aromatic ring in the main chain is more preferable. The main chain structure is not particularly limited as long as it has an aromatic ring, but a main chain structure having sufficient mechanical strength and physical durability, for example, used as an engineering plastic is preferable. Specific examples of the polymer having an aromatic ring in the main chain include polysulfone, polyethersulfone, polyphenylene oxide, polyarylene ether polymer, polyphenylene sulfide, polyphenylene sulfide sulfone, polyparaphenylene, polyarylene polymer, polyarylene ketone, poly Examples include polymers containing at least one component such as ether ketone, polyarylene phosphine hydroxide, polyether phosphine oxide, polybenzoxazole, polybenzthiazole, polybenzimidazole, polyamide, polyimide, polyetherimide, polyimidesulfone and the like. It is done.

  Polysulfone, polyethersulfone, polyetherketone, and the like referred to here are generic names for polymers having a sulfone bond, an ether bond, and a ketone bond in the molecular chain thereof. Polyetherketoneketone, polyetheretherketone, It includes polyether ether ketone ketone, polyether ketone ether ketone ketone, polyether ketone sulfone and the like, and does not limit the specific polymer structure.

  Among the polymers having an aromatic ring in the main chain, polymers such as polyether ketone and polyether ketone sulfone are more preferable from the viewpoints of mechanical strength, physical durability, processability and hydrolysis resistance.

  The diol monomer in the present invention has two polymerizable hydroxy groups and is not particularly limited. For example, various aromatic dihydroxy compounds can be mentioned, and those obtained by introducing a sulfonic acid group into these aromatic dihydroxy compounds can be used as diol monomers having an ionic group. Preferable specific examples of the aromatic dihydroxy compound include groups represented by the following general formulas (X-1) to (X-29).

(The groups represented by the formulas (X-1) to (X-7) may be optionally substituted.)

(N and m are integers of 1 or more, and Rp represents an arbitrary organic group.)

  These may have a substituent. Those having an aromatic ring in the side chain are also preferred specific examples. Moreover, these can also be used together as needed.

  Among these, from the viewpoints of crystallinity, dimensional stability and mechanical strength, the groups represented by the general formulas (X-1) to (X-9) are more preferable, and most preferable is the general formula (X-1). To a group represented by (X-5), most preferably a group represented by formula (X-2) or (X-3).

  The dihalide monomer in the present invention has a polymerizable halogen such as chlorine, bromine and fluorine, and an aromatic active dihalide compound is a preferred example from the viewpoint of mechanical strength and durability. Moreover, what introduce | transduced the sulfonic acid group into these aromatic active dihalide compounds can be used as a dihalide monomer which has an ionic group. The monomers used in the desalting polycondensation of the present invention utilize, for example, an aromatic nucleophilic substitution reaction of an aromatic active dihalide compound and an aromatic dihydroxy compound, or an aromatic nucleophilic substitution reaction of a halogenated aromatic phenol compound. Can be synthesized.

  More preferable specific examples of the aromatic active dihalide compound include 4,4′-dichlorodiphenyl sulfone, 4,4′-difluorodiphenyl sulfone, 4,4′-dichlorodiphenyl ketone, 4,4′-difluorodiphenyl ketone, 4,4′-dichlorodiphenylphenylphosphine oxide, 4,4′-difluorodiphenylphenylphosphine oxide, 2,6-dichlorobenzonitrile, 2,6-difluorobenzonitrile and the like can be mentioned.

  Among these, 4,4′-dichlorodiphenyl ketone and 4,4′-difluorodiphenyl ketone are more preferable in terms of imparting crystallinity, mechanical strength, physical durability, water resistance, methanol resistance, and fuel crossover suppression effect. From the viewpoint of activity, 4,4′-difluorodiphenyl ketone is most preferred. These aromatic active dihalide compounds can be used alone, but a plurality of aromatic active dihalide compounds can also be used in combination.

  In the method for producing a polymer electrolyte membrane of the present invention, an electrolyte polymer containing a hydrolyzable group is used as a membrane and used as a precursor. The hydrolyzable group in the present invention is a hydrolyzable group. If it is not introduced, it is introduced into a polymer that is difficult to dissolve in a solvent, and it is temporarily introduced so that solution film formation and filtration can be easily performed on the assumption that it is removed by hydrolysis in a later step. It is a substituent for the purpose. The hydrolyzable group can be appropriately selected in consideration of reactivity, yield, stability of the hydrolyzable group-containing state, production cost, and the like.

  Examples of utilizing hydrolyzable groups include a method in which the site that eventually becomes a ketone is transformed into an acetal or ketal site to form a hydrolyzable group, and this site is hydrolyzed and converted to a ketone site after film formation in solution. Can do. Moreover, the method which makes a ketone site | part a hetero atom analog of acetal or a ketal site | part, for example, thioacetal and thioketal, is mentioned. Further, a method of making a sulfonic acid a soluble ester derivative, a method of introducing a t-butyl group as a soluble group into an aromatic ring, and det-butylating with an acid can be used in the same manner. From the viewpoint of imparting the crystal ability described later, it is preferable that the site that eventually becomes a ketone is transformed into a ketal site to form a hydrolyzable group.

  As the hydrolyzable group, an aliphatic group, particularly an aliphatic group containing a cyclic moiety is preferably used from the viewpoint of improving the solubility in a general solvent and reducing crystallinity, from the viewpoint of large steric hindrance.

  The position of the functional group for introducing the hydrolyzable group is more preferably the main chain of the polymer. When introduced into the main chain, the difference in state after introduction of hydrolyzable groups and after changing to stable groups after hydrolysis is large, the packing of the polymer chains becomes stronger, the solvent changes from soluble to insoluble, mechanical Strength and water resistance tend to increase. Here, the functional group present in the main chain of the polymer is defined as a functional group that breaks the polymer chain when the functional group is deleted. For example, this means that if the ketone group of the aromatic polyether ketone is deleted, the benzene ring and the benzene ring are broken.

  In the present invention, the structural unit containing a hydrolyzable group preferably contains at least one selected from the following general formulas (P3) and (P4).

(In the formulas (P3) and (P4), Ar _{1 to} Ar ₄ are any divalent arylene group, R ₁ and R ₂ are at least one group selected from H and an alkyl group, and R ₃ is any An alkylene group, E represents O or S, each of which may represent two or more groups, and the groups represented by the formulas (P3) and (P4) may be optionally substituted.)
Among these, the method in which E is O in the general formulas (P3) and (P4), that is, the ketone moiety is a ketal moiety, is most preferable in terms of the odor, reactivity, stability, and the like of the compound.

R ₁ and R _{2 in} formula (P3) are more preferably an alkyl group from the viewpoint of stability, more preferably an alkyl group having 1 to 6 carbon atoms, and most preferably an alkyl group having 1 to 3 carbon atoms. It is a group. Moreover, as R < ₃ > in general formula (P4), it is more preferable that it is a C1-C7 alkylene group from a stability point, Most preferably, it is a C1-C4 alkylene group. Specific examples of R ₃ include —CH ₂ CH ₂ —, —CH (CH ₃ ) CH ₂ —, —CH (CH ₃ ) CH (CH ₃ ) —, —C (CH ₃ ) ₂ CH ₂ —, —C. _{(CH 3) 2 CH (CH} 3) -, - C (CH 3) 2 O (CH 3) 2 -, - CH 2 CH 2 CH 2 -, - CH 2 C (CH 3) 2 CH 2 - and the like However, it is not limited to these.

Among the structural units of the general formula (P3) or (P4), those having at least the general formula (P4) in view of stability such as hydrolysis resistance in the process and solubility in a solvent are more preferably used. It is done. Furthermore, R _{3 in the} general formula (P4) is preferably an alkylene group having 1 to 7 carbon atoms, that is, a group represented by C _n1 H _2n1 (n1 is an integer of 1 to 7). From the viewpoint of ease of synthesis, it is most preferably at least one selected from —CH ₂ CH ₂ —, —CH (CH ₃ ) CH ₂ —, or —CH ₂ CH ₂ CH ₂ —.

A preferable organic group as Ar _{1 to} Ar ₄ in the general formulas (P3) and (P4) is a phenylene group, a naphthylene group, or a biphenylene group. These may be optionally substituted. In the present invention, it is more preferable that Ar ₃ and Ar ₄ in the general formula (P4) are both phenylene groups, and most preferably, both Ar ₃ and Ar ₄ are p- A phenylene group.

  In the present invention, examples of a method for hydrolyzing a ketone moiety such as a ketal include a method in which a precursor compound having a ketone group is reacted with a monofunctional and / or bifunctional alcohol in the presence of an acid catalyst. For example, by reacting the ketone precursor 4,4′-dihydroxybenzophenone in a solvent such as monofunctional and / or difunctional alcohols, aliphatic or aromatic hydrocarbons in the presence of an acid catalyst such as hydrogen bromide. Can be manufactured. The alcohol is an aliphatic alcohol having 1 to 20 carbon atoms.

  Of the monomers applied to the method for producing the polymer electrolyte membrane of the present invention, the diol monomer preferably has a hydrolyzable group in consideration of the reactivity of the monomer, and in step (1), it has a hydrolyzable group. It is essential to use a diol monomer. Among the diol monomers having a hydrolyzable group, the aromatic dihydroxy compounds are preferably compounds represented by the following general formulas (P3-1) and (P4-1), respectively, and aromatic with an aromatic active dihalide compound. It can be synthesized by a nucleophilic substitution reaction.

(In the general formula (P3-1) and (P4-1), AR1 to AR4 any divalent arylene group, at least one of the radicals _{R 1} and _{R 2} selected from H and alkyl radicals, _{R 3} Represents an arbitrary alkylene group, E represents O or S. The compounds represented by the general formula (P3-1) and the general formula (P4-1) may be optionally substituted.
Specific examples of particularly preferred aromatic dihydroxy compounds include compounds represented by the following general formulas (r1) to (r10), and derivatives derived from these aromatic dihydroxy compounds.

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

  The production method of the present invention is particularly effective when applied to a polymer having a crystallizable property (sometimes referred to as crystal ability in the present specification). In the present invention, “crystallizing ability” means that the polymer can be crystallized at a high temperature, has a crystallizable property, or has already been crystallized. An amorphous polymer means a polymer that is not a crystalline polymer and that does not substantially proceed with crystallization.

  In the present invention, the presence or absence of crystallinity of the polymer and the crystalline and amorphous states can be evaluated by a crystal-derived peak in wide-angle X-ray diffraction (XRD), a crystallization peak in differential scanning calorimetry (DSC), or the like. it can. For example, it is suitable for manufacturing an electrolyte membrane having a crystallization calorific value measured by differential scanning calorimetry of 0.1 J / g or more or a crystallinity measured by wide-angle X-ray diffraction of 0.5% or more.

  By having crystallinity, for example, an electrolyte membrane having a small dimensional change (swelling) in high-temperature water and high-temperature methanol, that is, excellent in hot water resistance and heat-resistant methanol properties can be obtained. When this dimensional change is small, the membrane is difficult to break during use as an electrolyte membrane, and the power generation performance and durability are good because it is difficult to swell and peel from the electrode catalyst layer. In particular, it exhibits excellent durability in a durability test (dry and wet cycle test) in which the electrolyte membrane accompanying power generation is repeatedly wetted and dried in an open circuit state.

  Therefore, the balance between the high proton conductivity and the characteristics of the hot water resistance and methanol resistance is an important characteristic required for the electrolyte membrane used in the polymer electrolyte fuel cell. An electrolyte membrane that can be used industrially can be produced.

Further, in the method for producing an electrolyte membrane of the present invention, a polymer precursor film-like material containing an ionic group is used, and the ionic group of the present invention is particularly an atomic group having a negative charge. Although not limited, those having proton exchange ability are preferred. As such a functional group, a sulfonic acid group, a sulfonimide group, a sulfuric acid group, a phosphonic acid group, a phosphoric acid group, and a carboxylic acid group are preferably used. Such an ionic group includes a case where it is a salt. Examples of the cation forming the salt include an arbitrary metal cation, NR ⁴⁺ (R is an arbitrary organic group), and the like. In the case of a metal cation, the valence and the like are not particularly limited and can be used. Specific examples of preferable metal ions include Li, Na, K, Rh, Mg, Ca, Sr, Ti, Al, Fe, Pt, Rh, Ru, Ir, and Pd. Among these, Na and K which are inexpensive and do not adversely affect the solubility and can be easily proton-substituted are more preferably used.

  Two or more kinds of these ionic groups can be contained in the polymer, and may be preferable by combining them. The combination is appropriately determined depending on the structure of the polymer. Among them, it is more preferable to have at least a sulfonic acid group, a sulfonimide group, and a sulfuric acid group from the viewpoint of high proton conductivity, and most preferable to have at least a sulfonic acid group from the viewpoint of hydrolysis resistance.

  The amount of ionic groups that can be utilized in the present invention can be expressed as a value of sulfonic acid group density (mmol / g), for example, in the case of sulfonic acid groups. Here, the ionic group density is the number of moles of ionic groups introduced per gram of the dried polymer electrolyte material, and the larger the value, the greater the amount of ionic groups. The ionic group density can be determined by elemental analysis, neutralization titration, or capillary electrophoresis.

  The electrolyte having an ionic group of the present invention contains other components, for example, an inactive polymer or an organic or inorganic compound having no conductivity or ionic conductivity, as long as the object of the present invention is not impaired. It doesn't matter.

  In the method for producing a polymer electrolyte membrane of the present invention, a method for polymerizing using a monomer having an ionic group is essential as a method for introducing an ionic group, but a method for introducing an ionic group by a polymer reaction is required. You may combine.

  As a polymerization method using a monomer having an ionic group, a monomer having an ionic group in a repeating unit may be used. If necessary, an appropriate hydrolyzable group is introduced, and after polymerization, hydrolysis is carried out by hydrolysis. What is necessary is just to remove a decomposable group.

  The method for introducing an ionic group by a polymer reaction will be described with an example. As a method for sulfonating an aromatic polymer, that is, a method for introducing a sulfonic acid group, for example, JP-A-2-16126 or A method described in JP-A-2-208322 is known. Specifically, for example, sulfonation by reacting an aromatic polymer with a sulfonating agent such as chlorosulfonic acid in a solvent such as chloroform or by reacting in concentrated sulfuric acid or fuming sulfuric acid. Can do. The sulfonating agent is not particularly limited as long as it sulfonates an aromatic polymer, and sulfur trioxide or the like can be used in addition to the above. When the aromatic polymer is sulfonated by this method, the degree of sulfonation can be easily controlled by the amount of the sulfonating agent used, the reaction temperature and the reaction time. Introduction of a sulfonimide group into an aromatic polymer can be achieved, for example, by a method of reacting a sulfonic acid group and a sulfonamide group.

Further, for example, the ionic group may be -SO ₃ H type or -SO ₃ M type (M is a metal) when a sulfonic acid group is taken as an example, but a part of the solvent is removed to form a film on the substrate. In the case of the present invention including a step of obtaining a product, the —SO ₃ M type (M is a metal) is preferred. The point of heat stability at the time of solvent drying and the cost reduction of manufacturing equipment are attained. The metal M may be any salt as long as it can form a salt with sulfonic acid, but Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, W, and the like are preferable. Among these, Li, Na, K, Ca, Sr, and Ba are more preferable, and Li, Na, and K are more preferable.

  The average sulfonic acid group density of the polymer to which the method for producing an electrolyte membrane of the present invention can be applied is preferably 0.5 to 5 mmol / g, more preferably 1.0 to 3 mmol / g, from the viewpoint of proton conductivity and durability. Most preferably, it is 1.5-2.5 mmol / g. By setting the sulfonic acid group density to 0.5 mmol / g or more, conductivity, that is, output performance can be maintained, and by setting it to 5 mmol / g or less, it is sufficient when used as an electrolyte membrane for a fuel cell. It is possible to obtain mechanical strength and long-term durability when containing water.

Next, since the manufacturing method of the polymer electrolyte membrane of the present invention must have the following steps, it will be described in detail.
(1) A diol monomer containing 20 to 100 mol% of a diol monomer having a hydrolyzable group and a dihalide monomer, the total content of the diol monomer having an ionic group and the dihalide monomer having an ionic group is 0 Step of obtaining an electrolyte prepolymer solution by dissolving in a solvent and bringing it into contact with a basic compound so as to be ˜20 mol% (2) A diol containing 10 mol% or more of a diol monomer having an ionic group A dihalide monomer containing 20 to 100 mol% of a monomer and a dihalide monomer having an ionic group, a total content of a diol monomer having an ionic group and a dihalide monomer having an ionic group is the step (1). Including the total of diol monomer having ionic group and dihalide monomer having ionic group Step (3) Step (2) to obtain an electrolyte polymer solution by adding to the electrolyte prepolymer solution obtained in the step (1) and dehydrating by heating so that the value + 10 to 100 mol% The subsequent electrolyte polymer solution is subjected to solid-liquid separation by direct centrifugal separation to form a coating solution (4) The coating solution after the step (3) is cast-coated on a substrate, and the solvent is evaporated by heating. (5) The step of forming a film-like material by using the film-like material as a precursor and bringing it into contact with an acidic aqueous solution to form an electrolyte membrane. Step (1) forms a polymer structure mainly responsible for functions related to durability. To implement The details of the hydrolyzable group and the diol monomer of the diol monomer having a hydrolyzable group are as described above.

  It does not specifically limit as diol monomers of a process (1), What is necessary is just to be able to superpose | polymerize with dihalide monomers, and the details are as above-mentioned, However, Among diol monomers, the diol monomer which has a hydrolysable group is 20- It is necessary to contain 100 mol%, and by containing 20 mol% or more, even a polymer that has high crystallinity and is usually difficult to dissolve in a solvent can be solubilized in a solvent as a precursor polymer and processed into a film shape. Becomes easy. Preferably it is 40 mol% or more, More preferably, it is 60 mol% or more. In the case where crystallinity is imparted as an electrolyte membrane, 4,4′-dihydroxybenzophenone and the like are preferable.

  The mol% here means that the content of the diol monomer or dihalide monomer having a specified substituent among the diol monomers or dihalide monomers used in each step represents the content in the electrolyte polymer. It does not represent. Nor does it indicate the content of substituents. The same applies hereinafter.

  The dihalide monomers in step (1) are not particularly limited as long as they can be polymerized with diol monomers. Details are as described above.

  In this step (1), the total content of the diol monomer having an ionic group and the dihalide monomer having an ionic group needs to be 0 to 20 mol%. By setting the content to 20 mol% or less, the durability of the final electrolyte membrane can be improved without inhibiting the crystal ability. It is more preferable not to use it at 10 mol% or less.

  In the step (1), it is necessary to dissolve the monomers in a solvent and bring them into contact with a basic compound for heat dehydration. The polycondensation reaction must be performed in a solvent from the viewpoint of increasing the molecular weight. The solvent that can be used is not particularly limited as long as the monomers can be dissolved. However, even if it is difficult to completely dissolve the monomers, they may be partially dissolved. Specific solvents include N, N-dimethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, sulfolane, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphontriamide, etc. Examples of the aprotic polar solvent include, but are not limited to, and any solvent may be used as long as it can be used as a stable solvent. These organic solvents may be used alone or as a mixture of two or more.

  Examples of the basic compound include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate and the like. For example, as long as an aromatic diol can be converted into an active phenoxide structure, It can use without being limited to these.

  Although a well-known method can be normally used for the contact of monomers and a basic compound, stirring contact is mentioned with a stirring blade within the reaction container provided with the stirrer. When the basic compound does not dissolve in the solvent, increase the stirring speed, devise the shape of the stirring blade so that turbulent flow occurs, or devise the basic compound not to stay in a part of the reaction vessel It is preferable to do this. Moreover, an ultrasonic wave or a screw system can also be used, and a mixer that can rotate locally at a high speed may be installed.

  In the step (1) of the method for producing an electrolyte membrane of the present invention, it is necessary to heat and dehydrate water generated as a by-product during polymerization and water contained in the monomer and other raw materials. As this method, it is preferable to remove water as an azeotrope from the system by coexisting an azeotropic agent that can be azeotroped with water, such as toluene, irrespective of the polymerization solvent. The azeotropic agent used to remove water is generally any inert compound that does not substantially interfere with the polymerization, co-distills with water and boils between about 25 ° C and about 250 ° C. Examples of the azeotropic agent include benzene, toluene, xylene, chlorobenzene, methylene chloride, dichlorobenzene, and trichlorobenzene. The boiling point of the azeotropic agent is preferably lower than the boiling point of the polar solvent used. In the case where an azeotropic agent is not used, a case where a high reaction temperature, for example, a temperature of 200 ° C. or higher is used, particularly a case where an inert gas is continuously sprayed on the reaction mixture. In order to prevent oxidative degradation at high temperatures, in general, the polymerization reaction is preferably performed in an inert atmosphere, and preferably in the absence of oxygen.

  The reaction proceeds by mixing the monomer solution and the basic compound by a generally known method and heating, but the heating temperature in step (1) is preferably 0 to 250 ° C, more preferably 100 to 200 ° C. preferable. When the temperature is lower than 0 ° C, the reaction tends not to proceed sufficiently. When the temperature is higher than 250 ° C, decomposition of the monomer occurs.

  It is preferable to charge so that it may become 5-70 weight% as a density | concentration of the monomers of a process (1). If it is 5% by weight or less, the degree of polymerization tends to be difficult to increase, and a long time is required until the desired molecular weight. On the other hand, when it is more than 70% by weight, the reaction product tends to precipitate and the workability is poor.

  Next, the step (2) will be explained. This step is a polymer unit mainly responsible for the proton conduction function directly in the reaction vessel in which the polymer structure mainly responsible for the durability-related function is formed in the step (1). Is a step in which the monomers for forming are dropped and polymerization is continued. In order to enhance the proton conduction function, it is preferable to have a more hydrophilic polymer structure and locally increase the density of ionic groups such as sulfonic acid groups, so that not only dihalide monomers having ionic groups but also ions It is a feature of the present invention to use together diol monomers containing a functional group.

  Even at the same ionic group concentration, it is considered preferable to use not only dihalide monomers but also diol monomers to introduce ionic groups, since ionic groups are effectively arranged. In order to increase the density of ionic groups using only dihalide monomers, it is conceivable to introduce an ionic group into the side chain instead of the main chain alone, but such an ineffective method is adopted. You do n’t have to.

  The diol monomer in the step (2) is not particularly limited as long as it can be polymerized with dihalide monomers, and the details are as described above. Among the diol monomers, 10 mol% of the diol monomer having an ionic group is used. It is necessary to include the above, and it is considered that the ionic group is effectively arranged as described above by including 10 mol% or more. Preferably, it has a case of having an ionic group of 20 mol% or more. The diol monomer having an ionic group described in the step (2) is preferably the following general formula (P1).

  The dihalide monomers in the step (2) are not particularly limited as long as they can be polymerized with diol monomers, and the details are as described above, but the dihalide monomers have an ionic group-containing dihalide monomer of 20 to 100. It is necessary to contain it in an amount of 40% by mole or more, more preferably 60% by mole or more, and a case having 95% by mole or more ionic groups is also very preferable.

  As the dihalide monomer having an ionic group, it is preferable to use a compound in which an ionic acid group is introduced into an aromatic active dihalide compound because the amount of the ionic group can be precisely controlled. As the ionic group, a sulfonic acid group is preferable from the viewpoint of cost and ease of handling, and a suitable example of a dihalide monomer having an ionic group is 3,3′-disulfonate-4,4′-dichlorodiphenyl. Sulfone, 3,3′-disulfonate-4,4′-difluorodiphenyl sulfone, 3,3′-disulfonate-4,4′-dichlorodiphenyl ketone, 3,3′-disulfonate-4,4′-difluoro Diphenyl ketone, 3,3′-disulfonate-4,4′-dichlorodiphenylphenylphosphine oxide, 3,3′-disulfonate-4,4′-difluorodiphenylphenylphosphine oxide, etc. It is not limited to.

  As the diol monomer containing an ionic group, it is preferable to use a compound in which an ionic group is introduced into an aromatic dihydroxy compound because the amount of the ionic group can be precisely controlled. As the ionic group, a sulfonic acid group is preferable from the viewpoint of cost and ease of handling. Preferred examples of the diol monomer having an ionic group include 3,3′-disulfonate-4,4′-dihydroxydiphenylsulfone. 3,3′-disulfonate-4,4′-hydroxydiphenyl sulfone, 3,3′-disulfonate-4,4′-dihydroxydiphenyl ketone, 3,3′-disulfonate-4,4′-dihydroxydiphenyl Ketones, 3,3′-disulfonate-4,4′-dihydroxydiphenylphenylphosphine oxide, 3,3′-disulfonate-4,4′-dihydroxyphenylphenylphosphine oxide, and the like. It is not limited.

  In terms of proton conductivity and hydrolysis resistance, a sulfonic acid group is most preferable as an ionic group, but the monomer having an ionic group used in the present invention may have another ionic group. . Among them, from the viewpoint of proton conductivity and durability, dihalides containing ionic surname groups are 3,3′-disulfonate-4,4′-dichlorodiphenyl ketone, 3,3′-disulfonate-4,4′-difluoro. Diphenyl ketone is more preferable, and 3,3′-disulfonate-4,4′-difluorodiphenyl ketone is most preferable from the viewpoint of polymerization activity. The dihalide containing an ion surname group is more preferably 3,3′-disulfonate-4,4′-dihydroxydiphenyl ketone or 3,3′-disulfonate-4,4′-dihydroxydiphenyl ketone, From the viewpoint, 3,3′-disulfonate-4,4′-difluorodiphenyl ketone is most preferable.

  In this step (2), the total content of the diol monomer having an ionic group and the dihalide monomer having an ionic group needs to include the value of the total content of step (1) +10 to 100%. In the case where the effect of the block polymer is obtained by including +10 mol% or more of the total content value of the diol monomer having an ionic group and the dihalide monomer having an ionic group in the step (1), and an electrolyte membrane is obtained. Sufficient proton conductivity can be obtained. The total content of the diol monomer having an ionic group and the dihalide monomer having an ionic group is preferably 40 mol% or more, more preferably 60 mol% or more, and the ionic group may contain 95 mol% or more ionic groups. Highly preferred.

  Further, as in the step (1), it is necessary to dissolve monomers in a solvent in order to obtain a stable polymer, and the same solvent as in the above step (1) can be used. In addition, when monomers having an ionic group are difficult to dissolve in a solvent, addition of 1,4,7,10,13,17-hexaoxacyclooctadecane or the like is preferable, and monomers having an ionic group are used as a solvent. It is very preferable to use it by dissolving it from the viewpoint of controlling the ionic group density of the electrolyte membrane. In particular, when dihalide monomer and diol monomer having sulfonic acid group ends substituted with Na or K are used as ionic groups, N-methyl-2-pyrrolidone is used as a solvent, and toluene is used as an azeotropic agent. The monomer dissolving effect of 4,7,10,13,17-hexaoxacyclooctadecane is remarkable and can be preferably used.

The molecular weight of the polymer in the step (1) at the stage of mixing the monomers in the step (2) with the step (1) is preferably 3000 to 100,000 from the viewpoint of forming a functional separation structure as a final electrolyte membrane. The molecular weight here is a weight average molecular weight in terms of styrene by GPC measurement.
After mixing the monomers of step (2) into step (1), they are brought in due to the water content of the water produced by the reaction of the monomers of step (2) and water produced by the remaining reaction of step (1), such as water. It is necessary to continue the heat dehydration of the water. At this time, the basic compound may be mixed with the monomers in the step (2) and added in the form of a slurry, but it is necessary for the reaction of the diols added in the step (2) in the step (1) in advance. It is preferable to prepare an appropriate amount from the viewpoint of productivity. Basic compounds usually have low solubility in organic solvents and tend to become slurries. Addition during the reaction is not only inferior in workability, but also causes a shift in the charged composition during mixing work, and the molecular weight does not increase. It becomes.

  In addition, as a method of mixing the monomer solution of step (2) with the reaction solution of step (1), generally known methods can be applied, and the monomer solution of step (2) is added to the dropping container so that air or the like is not mixed. Examples thereof include a method of dropping in advance, a method of feeding with a pump, and a method of feeding from a pressure vessel.

  After all the monomers are mixed, it is preferable to increase the molecular weight by proceeding polycondensation by a generally known method. The polymerization can be performed in a temperature range of 100 to 350 ° C., but a temperature of 150 to 250 ° C. is preferable. When the temperature is lower than 100 ° C., the reaction does not proceed sufficiently. When the temperature is higher than 250 ° C., decomposition of the polymer also tends to start to occur.

  For example, when N-methyl-2-pyrrolidone is used as a solvent, toluene is used as an azeotropic agent, and potassium carbonate is used as a basic compound, dehydration is performed with an azeotropic agent until the dehydration of stoichiometric values corresponding to all monomers is completed. It is preferable to continue, and it is preferable to perform a dehydration reaction at 180 ° C. or lower in order to prevent decomposition of the polymer and deactivation of the polymerization activity. In addition, if it is difficult to determine whether the amount of dehydration is derived from the water produced by the reaction or the moisture content of the material, it is very preferable to monitor the carbon dioxide gas accompanying the dehydration reaction, which enables stable control of the polymerization reaction. . It is preferable to continue dehydration with an azeotropic agent until the generation of carbon dioxide gas is stopped. After completion of the dehydration, the azeotropic agent may be removed and further heated, and it is preferable to heat in the range of 195 ° C. to 210 ° C. from the viewpoint of increasing the molecular weight.

  The molecular weight of the polymer thus obtained is 50,000 to 5,000,000, preferably 100,000 to 1,000,000 in terms of polystyrene-equivalent weight average molecular weight. If it is less than 50,000, the mechanical strength, physical durability, solvent resistance and the like are insufficient, and when used in a fuel cell, the wet / dry cycle test is particularly insufficient. On the other hand, when it exceeds 100 million, there are problems such as high solution viscosity and poor processability.

  In the present invention, as shown in the step (3), a step of solid-liquid separation of the polymer solution after the heat dehydration step by a direct centrifugation method is essential. In other words, high-quality separation of the polymer solution from the salt such as KF and NaF by-produced in the polycondensation reaction of the present invention and the remaining basic compound, or the residual monomer or gelled substance insoluble in the solvent, and the polymer solution is efficient. And is important for the production of high performance electrolyte membranes. The term “directly” as used herein means that the polymerized solution is solid-liquid separated by centrifugation as it is without using a method in which the salt is soluble and the polymer is not soluble, for example, by contacting with water and precipitating the polymer in water. It means to do. At this time, the polymer may be diluted with a solvent in which the polymer is soluble in order to improve the efficiency of solid-liquid separation, and a filter filtration step may be performed before or after centrifugation. In particular, it is preferable to perform filter filtration before the step (4) from the viewpoint of removing foreign substances in the electrolyte membrane. Furthermore, it is preferable from the viewpoint of obtaining a high-quality electrolyte membrane to include a step of removing the solvent with a solvent diluting or concentrating device or the like and adjusting to a viscosity suitable for the coating device. In particular, by this step (3), it is possible to efficiently and stably purify a function-separated electrolyte membrane precursor solution having a hydrolyzable group, a polymer unit having high crystallinity, and a high proton conduction unit. It became possible and contributed greatly to the present invention.

  If conventional precipitation purification in water is applied, part of the crystallizable part becomes insoluble in the solvent due to decomposition of the hydrolyzable group, and part that cannot be re-dissolved in the solvent for coating tends to occur, and higher proton conductivity. The unit is easy to swell, so it easily swells and is extremely inferior in workability. By inventing a method of solid-liquid separation by direct centrifugation, these problems can be solved, and furthermore, there is no re-dissolution operation, so that the upper limit of the molecular weight of the polymer in the production process can be increased and a highly durable electrolyte membrane can be obtained. Obtainable.

  For the centrifugation in the present invention, generally known methods can be applied. It is preferable to adjust the viscosity of the polymerization solution from the viewpoint of efficient removal of salt. When performing centrifugation, the polymerization solution concentration is preferably 100 poise or less, more preferably 50 poise, and still more preferably 10 poise or less. If it exceeds 100 poise, the centrifugal effect is low, high centrifugal force is required for a long time, and it is difficult to perform centrifugation with an industrial apparatus. The centrifugal force can be determined experimentally as appropriate, such as the specific gravity difference between the generated salt and the polymer solution, the viscosity of the polymerization solution, the solid content, and the apparatus used. The centrifugal force is 5000 G or more, preferably 10,000 G or more, more preferably 20000 G or more, and an apparatus that can be operated continuously except during the removal of the cake is industrially suitable.

  Filter filtration may be performed before or after the centrifugation step. Filter filtration can also be applied by a generally known method, and conditions can be appropriately determined depending on the size of the salt to be removed from the polymerization solution, the viscosity of the polymerization solution, etc. A method can be adopted, and the liquid to be filtered may be heated. The filter is not particularly limited, and can be appropriately selected according to the throughput of the polymerization solution such as a metal mesh, a cellulose-based filter, a glass fiber filter, a membrane filter, a filter cloth, a filter plate, and a filtration device.

  Moreover, in order to adjust the viscosity and solid content suitable for coating before the coating step, it is also useful to concentrate the polymerization solution by vacuum distillation or ultrafiltration. In particular, when the viscosity of the polymerization solution is adjusted in order to increase the efficiency of centrifugal separation and filter filtration, it is preferable to concentrate. Further, the coating property may be improved by concentrating the polymerization solution. For this concentration, a generally known method can be applied, and a concentration device that is equipped with a stirrer or the like and can prevent the formation of a film due to the volatilization of the solvent can be used more preferably. Further, it is preferable to reuse the solvent recovered by concentration from the viewpoint of productivity and environmental protection.

  In the present invention, as shown in the step (4), the step of forming a film-like product by casting the polymer solution after the solid-liquid separation step on a substrate and heating and evaporating the solvent is essential.

  As the base material on which the polymer solution is applied, generally known materials can be used, but endless belts or drums made of metals such as stainless steel, films made of polymers such as polyethylene phthalate, polyimide and polysulfone, glass plates, release papers, etc. Can be mentioned. For metal, etc., the surface is mirror-finished, for polymer films, etc., the coated surface is corona-treated, peeled off, and when continuously coated in roll form, the back of the coated surface is peeled off and wound. It is also possible to prevent the electrolyte membrane and the back side of the coated base material from adhering after removal. In the case of a film substrate, the thickness is not particularly limited, but is preferably about 25 μm to 200 μm from the viewpoint of handling.

  As a method of processing the polymer of the present invention into a film, the polymer solution is knife coat, direct roll coat, gravure coat, spray coat, brush coat, dip coat, die coat, vacuum die coat, curtain coat, flow coat, spin coat, A technique of cast coating on a substrate by reverse coating, screen printing or the like can be applied. From the viewpoint of productivity, it may be cast on both sides of the substrate.

  As a method for removing the solvent of the polymer solution coated on the substrate, a heating evaporation step such as heating of the base material, hot air, infrared heater, electromagnetic induction heating or the like is preferable from the viewpoint of facility versatility and productivity. A known method such as a wet coagulation method in which a part of the solvent is heated and evaporated and then contacted with a solvent in which the polymer does not dissolve can be selected. Further, when processing into a film shape, even if a solvent, a plasticizer, or the like remains in the electrolyte membrane, it may be a self-supporting membrane that can be handled.

  Although there is no restriction | limiting in particular as a film thickness of the electrolyte membrane precursor obtained at a process (4), Usually a thing of 3-200 micrometers is used suitably. A thickness of more than 3 μm is preferable to obtain a membrane strength that can withstand practical use, and a thickness of less than 200 μm is preferable to reduce membrane resistance, that is, to improve power generation performance. A more preferable range of the film thickness is 5 to 100 μm, and a more preferable range is 8 to 50 μm. This film thickness can be controlled by various methods depending on the coating method. For example, when coating with a comma coater or direct coater, it can be controlled by the solution concentration or the coating thickness on the substrate, and by slit die coating, it is controlled by the discharge pressure, the clearance of the die, the gap between the die and the base material, etc. be able to.

  Furthermore, as shown in step (5), the step of using the film-like material as a precursor and bringing it into contact with an acidic aqueous solution to form an electrolyte membrane is essential. When the ionic group is a metal salt, the hydrolysis efficiency of the hydrolyzable group can be achieved at the same time as the purpose of proton exchange, so that the production efficiency can be improved. The acidic aqueous solution may be heated to accelerate the reaction. The acidic aqueous solution is not particularly limited, such as sulfuric acid, hydrochloric acid, nitric acid, and acetic acid, and the temperature, concentration, and the like can be appropriately selected experimentally. From the viewpoint of productivity, it is preferable to use a 30% by weight or less sulfuric acid aqueous solution of 80 ° C. or less.

  In addition, if fine salt or residual monomer remains in the previous step, the salt portion tends to be the starting point and the durability of the electrolyte membrane tends to decrease. Solvents and the like can also be removed.

  It is also effective to wash with water or a solvent that does not affect the electrolyte membrane before contacting with an acidic aqueous solution. When using 1,4,7,10,13,17-hexaoxacyclooctadecane, etc. Recycling is facilitated by extracting from the precursor film in advance.

  In addition, it is preferable that the electrolyte membrane is brought into contact with an acidic aqueous solution and then washed with water so that the acidic aqueous solution does not remain on the surface. Further, it may be dried for storage or immersed in water. May be saved.

  Moreover, there is no restriction | limiting in particular as a method of making it contact with acidic aqueous solution, You may make it contact in the state which peeled the film-like material from the coating base material, and you may make a film-like material contact the whole base material. Further, it may be cut into an arbitrary size and contacted with the acidic aqueous solution in a single sheet, or may be continuously contacted with the acidic aqueous solution in a roll shape.

The manufacturing method of the electrolyte membrane of this invention can also have the process of following (6) (7) instead of process (1) (2).
(6) Diol monomers containing 10 mol% or more of diol monomers having ionic groups and dihalide monomers containing 20 to 100 mol% of dihalide monomers having ionic groups, diol monomers and ions having ionic groups The total content of the dihalide monomer having a functional group is the total content value of step (7) + 10 to 100 mol%, dissolved in a solvent, brought into contact with a basic compound and dehydrated by heating. Step for obtaining electrolyte prepolymer solution (7) Diol monomer and dihalide monomer containing 20 to 100 mol% of diol monomer having hydrolyzable group, diol monomer having ionic group and dihalide having ionic group The electrolyte composition obtained in the step (6) was adjusted so that the total monomer content was 0 to 20 mol%. Step of adding to the polymer solution and dehydrating by heating to obtain the electrolyte polymer solution In other words, the polymer unit mainly responsible for the proton conduction function is formed by simply switching the order of step (1) and step (2). After that, monomers for polymer units mainly responsible for durability-related functions such as mechanical strength are added and are substantially the same.

Furthermore, the manufacturing method of the electrolyte membrane of this invention can also have the process of following (8) (9) (10) instead of process (1) (2) and process (6) (7).
(8) A diol monomer containing 20 to 100 mol% of a diol monomer having a hydrolyzable group and a dihalide monomer, the total content of the diol monomer having an ionic group and the dihalide monomer having an ionic group is 0 Step of obtaining an electrolyte prepolymer solution by dissolving in a solvent and bringing it into contact with a basic compound so as to be ˜20 mol% (9) A diol containing 10 mol% or more of a diol monomer having an ionic group A dihalide monomer containing 20 to 100 mol% of a monomer and a dihalide monomer having an ionic group, a total content of a diol monomer having an ionic group and a dihalide monomer having an ionic group is the step (8). Including the total of diol monomer having ionic group and dihalide monomer having ionic group An electrolyte prepolymer solution that is dissolved in a solvent so as to be 10 to 100 mol% of the amount of diol and contains 10 mol% or more of a diol group having an ionic group, and is heated and dehydrated in a state where it can come into contact with a basic compound. Step (10) The step (8) solution and the step (9) solution are directly mixed and heated and dehydrated. That is, the step (1) and the step (2) are performed independently and are combined later. It is a manufacturing method in which the reaction unit is directly mixed after forming separately the polymer unit mainly responsible for proton conduction function and the polymer unit mainly responsible for durability related functions such as mechanical strength. Are identical.

  For mixing, the reaction solution may be directly pumped from one reaction vessel to the other reaction vessel, or a pump or the like may be used. The temperature at the time of mixing is not particularly limited and may be room temperature or a heating dehydration temperature. Different temperatures may be used.

  In addition, after the step (1), the step (6), the step (8), and the step (9), a step of once purifying and re-dissolving the electrolyte prepolymer may be included. Are the same. In addition, there are many combinations such as adding step (7) after step (2), adding step (2) after step (7), etc., but the contents etc. match. If so, they are substantially the same.

  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) Density of sulfonic acid group A sample of a membrane serving as a specimen was immersed in pure water at 25 ° C. for 24 hours, vacuum-dried at 40 ° C. for 24 hours, and then measured by elemental analysis. Carbon, hydrogen, and nitrogen were analyzed by a fully automatic elemental analyzer varioEL, sulfur was analyzed by a flask combustion method / barium acetate titration, and fluorine was analyzed by a flask combustion / ion chromatograph method. The sulfonic acid group density per unit gram (mmol / g) was calculated from the composition ratio of the polymer.

(2) Weight average molecular weight The weight average molecular weight of the polymer was 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 weight average molecular weight was determined.

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

(4) Crystallization calorimetry by differential scanning calorimetry (DSC) Preliminarily drying an electrolyte membrane (3.5 to 4.5 mg) as a specimen at a temperature at which sulfonic acid groups do not decompose (for example, 40 to 100 ° C.) After removing the moisture, the weight is measured. At this time, since the chemical structure or higher order structure of the polymer may change, the temperature is not raised above the crystallization temperature or the thermal decomposition temperature. After measuring the weight, the electrolyte membrane was subjected to temperature modulation differential scanning calorimetry at the first heating stage under the following conditions.

DSC apparatus: DSC Q100 manufactured by TA Instruments
Measurement temperature range: 25 ° C. to thermal decomposition temperature (eg, 310 ° C.)
Temperature increase rate: 5 ° C / min Amplitude: ± 0.796 ° C
Sample amount: about 4mg
Sample pan: Aluminum crimp pan Measurement atmosphere: Nitrogen 50 ml / min
Pre-drying: Vacuum drying 60 ° C., 1 hour A value obtained by doubling the amount of heat from the low temperature side to the peak top was calculated as the amount of crystallization heat. Further, since the specimen contained water, the water content was calculated from the detected heat of evaporation of water, and the weight of the polymer electrolyte material was corrected. The heat of evaporation of water is 2277 J / g.

Weight of water in sample (g) = heat of sample evaporation (J / g) × sample amount (g) / 2277 (J / g)
Crystallization heat quantity correction value (J / g) = crystallization heat quantity (J / g) × sample quantity (g) / (sample quantity−weight of water in sample (g))
(5) Observation of phase separation structure by transmission electron microscope (TEM) A film sample was cut into a size of 5 × 15 mm, embedded in a visible curable resin, and fixed by irradiation with visible light for 30 seconds.

  The flakes were cut at room temperature using an ultramicrotome, and the obtained flakes were collected on a Cu grid and subjected to TEM observation. Observation was carried out at an acceleration voltage of 100 kV, and photography was carried out so that the photographic magnifications were × 5,000, × 20,000, and × 50,000. As the equipment, an ultramicrotome ULTRACUT UCT (Leica) and TEM H7650 (Hitachi) were used.

(6) Dry / wet cycle test The dry / wet cycle of the membrane was caused in an actual power generation state and used as a comprehensive index of mechanical durability and chemical durability. The greater the number of cycles, the better the mechanical and chemical durability.

Specifically, the electrolyte membrane is cut into a 10 cm square, and two 5 cm square BASF fuel cell gas diffusion electrodes “ELAT (registered trademark) LT120ENSI” (5 g / m ² Pt) are arranged so as to sandwich the membrane. And it pressed at 150 degreeC and 5 Mpa for 5 minutes, and produced the membrane electrode composite_body | complex. The membrane electrode assembly is set in a JARI standard cell “Ex-1” (electrode area 25 cm ² ) manufactured by Eiwa Co., Ltd., and is used as a power generation evaluation module. The start-up and stop are repeated under the following conditions. The number of times that the open circuit voltage at the time of stoppage of less than 2V or less than 0.8V was evaluated.
-Electronic load device: Kikusui Electronics Co., Ltd. electronic load device "PLZ664WA"
・ Cell temperature: Always 80 ℃
・ Gas humidification condition: 50% RH for both anode and cathode
・ Start-up supply gas; anode is hydrogen, cathode air ・ Start-up load current: 1 A / cm ²
・ Gas utilization rate at startup; anode is 70% of stoichiometry, cathode is 40% of stoichiometry
・ Start-up time: 3 minutes ・ Stop supply gas flow rate: 0.25 L / min for anode hydrogen, 1 L / min for cathode air
-Stop time: 3 minutes-When switching between start and stop: Dry nitrogen was supplied to the anode and dry air was supplied to the cathode at 1 L / min for 1 minute to dry the electrolyte membrane.

(7) High-temperature low-humidity power generation evaluation As in (6) above, a power generation evaluation module is used, and power generation evaluation is performed under the following conditions. From 0 A / cm ² to 1.2 A / cm ² until the voltage is 0.1 V or less The current was swept. In the present invention, voltages at a current density of 1 A / cm ² were compared.
-Electronic load device: Kikusui Electronics Co., Ltd. electronic load device "PLZ664WA"
・ Cell temperature: Always 80 ℃
-Gas humidification conditions: 30% RH for both anode and cathode
・ Gas utilization: 70% of stoichiometry for anode, 40% of stoichiometry for cathode
Synthesis example 1
Synthesis of 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane (K-DHBP) In a 500 ml flask equipped with a stirrer, thermometer and distillation tube, 49.5 g of 4,4'-dihydroxybenzophenone, Charge and dissolve 134 g of ethylene glycol, 96.9 g of trimethyl orthoformate and 0.50 g of p-toluenesulfonic acid monohydrate. 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 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane.

Synthesis example 2
Synthesis of disodium 3,3′-disulfonate-4,4′-difluorobenzophenone 109.1 g (Aldrich reagent) of 4,4′-difluorobenzophenone in 150 mL of fuming sulfuric acid (50% SO ₃ ) (Wako Pure Chemical Industries, Ltd.) The reaction was carried out at 100 ° C. for 10 hours. 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%.

Synthesis example 3
Synthesis of disodium 3,3′-disulfonate-4,4′-dihydroxybenzophenone Disodium 3,3′-disulfonate-4 obtained in Synthesis Example 2 was added to a 1 L flask equipped with a stirrer, a thermometer and a reflux tube. , 4′-difluorobenzophenone 125 g and 700 mL of 15% NaOH aqueous solution were added, and the mixture was heated to reflux at 100 ° C. for 7 hours. After neutralizing with 1M hydrochloric acid and equipped with a distillation tube, toluene was added, water was azeotroped and removed out of the system to obtain a compositional organism. Thereafter, recrystallization was performed to obtain disodium 3,3′-disulfonate-4,4′-dihydroxybenzophenone represented by the above general formula (G3).

Example 1
Process (1)
A stirrer, a nitrogen introducing tube, and a dropping funnel were added to a 4000 mL reaction vessel equipped with a Dean-Stark trap, and 28.93 g (0.11 mol) of K-DHBP which is a diol monomer containing a hydrolyzable group obtained in Synthesis Example 1 above. And 4,4′-dihydroxybenzophenone (6.00 g (Aldrich reagent, 0.028 mol)), and after nitrogen substitution, after dissolving uniformly in 170 g of N-methyl-2-pyrrolidone (NMP) and 100 g of toluene, 199 g of potassium (Aldrich reagent, 1.44 mol) was added.

 Next, 31,16 g of 4,4′-difluorobenzophenone (Aldrich reagent, 0.14 mol), 30 g of NMP, and 60 g of toluene were added, and the mixture was heated with stirring to form an azeotrope of toluene and water at a reaction liquid temperature of 155 ° C. Dehydration was performed while refluxing. When the dehydration amount reached 2.5 g (100% dehydration rate vs. stoichiometric value), 0.5 ml of the reaction solution was sampled and the molecular weight was measured. The weight average molecular weight was 6000. In this step, the content of the diol monomer containing a hydrolyzable group in the diol monomer in this step is 80.0 mol%, and the diol monomer having an ionic group and the diester having an ionic group are contained. The total content of halide monomers was 0 mol%.

Process (2)
Next, 255.4 g (0.56 mol) of disodium 3,3′-disulfonate-4,4′-difluorobenzophenone obtained in Synthesis Example 2 as a dihalide monomer having an ionic group in another container, NMP (1870 g) ), 1,4,7,10,13,17-hexaoxacyclooctadecane (140 g) was added and dissolved uniformly. Furthermore, 46.85 g (0.112 mol) of disodium 3,3′-disulfonate-4,4′-dihydroxybenzophenone obtained in Synthesis Example 3 as a diol monomer having an ionic group in another container, and NMP (340 g) The mixture was uniformly dissolved and mixed. Further, 86.78 g (0.336 mol) of K-DHBP obtained in Synthesis Example 1 and 23.99 g (Aldrich reagent, 0.112 mol) of 4,4′-dihydroxybenzophenone were added, and N-methyl-2-pyrrolidone (NMP) was added. 100 g of toluene and 140 g of toluene were added and dissolved uniformly, and then charged into a dropping funnel provided in the reaction vessel, and the atmosphere was replaced with nitrogen. In this step, the dihalide monomer having an ionic group is 100 mol% in the dihalide monomers, the diol monomer having an ionic group is 20 mol% in the diol monomers, the diol monomer having an ionic group and the ionic group The total content of dihalide monomers having groups was 60 mol%.

When the amount of dehydration in step (1) reached 2.5 g, the entire amount was dropped from the dropping funnel at a rate of 100 g / min, and dehydration was continued at a reaction solution temperature of 160 ° C. When the total amount of dehydration exceeds 12.6 g (100% dehydration rate vs. stoichiometric value), a part of toluene is distilled off and the reaction solution temperature is raised to 175 ° C. and maintained until the generation of carbon dioxide gas is reduced. did. Estimated reduction in carbon dioxide generation using Chino Corp. CO ₂ monitor MA1002-0P, the gas in the nitrogen line to be discharged from the reaction vessel was collected in 5cc syringe and injected into CO ₂ monitor, a carbon dioxide concentration When the value of atmospheric pressure was +200 ppm or less, the next process was started. Next, while distilling off toluene from the reaction vessel, the temperature of the reaction solution was raised to 200 ° C. and polymerization was continued. The change in the power consumption of the stirrer was confirmed with Watt Checker Model 2000MS1 manufactured by Measurement Technology Laboratory Co., Ltd., and the polymerization was stopped when the power consumption did not change for 30 minutes or more or a decreasing trend was observed for 10 minutes continuously. It was 270,000 when 0.5g was sampled from this reaction liquid and the molecular weight was measured. After completion of the polymerization, 1000 g of NMP was added and cooled to room temperature to obtain a polymerization stock solution A.

Step (3)
The polymerization stock solution A was set in an inverter / compact high-speed cooling centrifuge model 6930 manufactured by Kubota Seisakusho, an angle rotor RA-800, and solid-liquid separation was performed at 25 ° C. for 30 minutes with a centrifugal force of 20000 G. Since the cake and the supernatant liquid (coating liquid) could be separated cleanly, the supernatant liquid was recovered. Only the supernatant was pressure filtered through a 5 μm polytetrafluoroethylene (PTFE) filter and transferred to a separable flask. Next, it distilled under reduced pressure at 80 degreeC, stirring, NMP was removed until the viscosity of the supernatant liquid became 10 Pa.s, and the coating liquid A was obtained.

Process (4)
A 125 μm PET film (“Lumirror (registered trademark)” manufactured by Toray Industries, Inc.) was used as a substrate, and the coating liquid A was cast by a slit die and dried at 150 ° C. for 15 minutes.

Step (5)
Next, the dried film is peeled off from PET and immersed in pure water at 25 ° C. for 10 minutes to leave residual salt, residual monomer, residual potassium carbonate, residual NMP, residual 1,4,7,10,13,17-hexaoxacyclooctadecane. And the like, and then immersed in 10% by weight sulfuric acid at 60 ° C. for 30 minutes to hydrolyze hydrolyzable groups and proton exchange of metal salts of sulfonic acid groups. Next, this membrane was washed with pure water until the washing solution became neutral and dried at 60 ° C. for 30 minutes to obtain an electrolyte membrane A having a thickness of 15 μm.

  The electrolyte membrane A had a sulfonic acid group density of 3.25 mmol / g.

When this high-temperature low-humidification power generation evaluation was performed using this electrolyte membrane A, it was 700 mW / cm ² , and a dry-wet cycle test was performed 9000 times.

Example 2
The same procedure as in Example 1 was performed except that steps (1) and (2) in Example 1 were changed to steps (6) and (7).

Step (6)
The disodium 3,3′-disulfonate-4,4 obtained in Synthesis Example 2 as a dihalide monomer having an ionic group was added to a 4 L reaction vessel equipped with a Dean-Stark trap with a stirrer, a nitrogen introduction tube, and a dropping funnel. '-Difluorobenzophenone 255.4 g (0.56 mol), NMP (1870 g) and 1,4,7,10,13,17-hexaoxacyclooctadecane 140 g were added and dissolved uniformly. Further, 46.85 g (0.112 mol) of disodium 3,3′-disulfonate-4,4′-dihydroxybenzophenone obtained in Synthesis Example 3 as a diol monomer having an ionic group in another container, NMP (340 g) Were uniformly dissolved and mixed. Thereafter, 86.78 g (0.336 mol) of K-DHBP obtained in Synthesis Example 1 and 20.86 g of 4,4′-biphenol (Wako Pure Chemical Reagent, 0.112 mol) were added, and 100 g of NMP and 140 g of toluene were added. After uniformly dissolving, 199 g of potassium carbonate (Aldrich reagent, 1.44 mol) was added. The dihalide monomer having an ionic group in this step is 100 mol% in the dihalide monomers, the diol monomer having an ionic group is 20 mol% in the diol monomers, the diol monomer having an ionic group, and The total content of dihalide monomers having an ionic group was 60.0 mol%.

  This solution was heated with stirring, and dehydration was performed while refluxing an azeotrope of toluene and water at a reaction liquid temperature of 165 ° C. When the dehydration amount reached 10.1 g (dehydration rate 100% vs. stoichiometric value), 0.5 ml of the reaction solution was sampled and the molecular weight was measured. The weight average molecular weight was 9000.

Step (7)
Next, 28.93 g (0.11 mol) of K-DHBP, which is a diol monomer containing the hydrolyzable group obtained in Synthesis Example 1, and 6.00 g of 4,4′-dihydroxybenzophenone (Aldrich Reagent, 0) were obtained in another container. .028 mol), 4,4′-difluorobenzophenone 31.16 g (Aldrich reagent, 0.14 mol), NMP 40 g, and toluene 60 g were added and dissolved uniformly. did. The content of the diol monomer containing a hydrolyzable group in the diol monomers in this step is 80.0 mol%, and the total content of the diol monomer having an ionic group and the dihalide monomer having an ionic group Was 0 mol%.

  When the amount of dehydration in step (1) reached 10.1 g, the entire amount was dropped from the dropping funnel at a rate of 100 g / min, and dehydration was continued at a reaction solution temperature of 160 ° C. When the total amount of dehydration exceeds 12.6 g (100% dehydration rate vs. stoichiometric value), a part of toluene is distilled off and the reaction solution temperature is raised to 175 ° C. and maintained until the generation of carbon dioxide gas is reduced. did.

Estimated reduction in carbon dioxide generation using Chino Corp. CO ₂ monitor MA1002-0P, the gas in the nitrogen line to be discharged from the reaction vessel was collected in 5cc syringe and injected into CO ₂ monitor, a carbon dioxide concentration When the value of atmospheric pressure was +200 ppm or less, the next process was started. Next, while distilling off toluene from the reaction vessel, the temperature of the reaction solution was raised to 200 ° C. and polymerization was continued. The change in the power consumption of the stirrer was confirmed with Watt Checker Model 2000MS1 manufactured by Measurement Technology Laboratory Co., Ltd., and the polymerization was stopped when the power consumption did not change for 30 minutes or more or a decreasing trend was observed for 10 minutes continuously. It was 200,000 when 0.5g was sampled from this reaction liquid and the molecular weight was measured. After completion of the polymerization, 1000 g of NMP was added and cooled to room temperature to obtain a polymerization stock solution D.

The subsequent steps were performed in the same manner as in Example 1 to obtain an electrolyte membrane D having a film thickness of 15 μm. The electrolyte membrane D had a sulfonic acid group density of 3.24 mmol / g. When this electrolyte membrane D was used for high-temperature low-humidification power generation evaluation, it was 650 mW / cm ² , and when the dry / wet cycle test was performed, it was 7600 times.

Example 3
The same procedure as in Example 1 was performed except that steps (1) and (2) in Example 1 were changed to steps (8), (9) and (10).

Step (8)
A stirrer, a nitrogen introducing tube, and a dropping funnel were added to a 4000 mL reaction vessel equipped with a Dean-Stark trap, and 28.93 g (0.11 mol) of K-DHBP which is a diol monomer containing a hydrolyzable group obtained in Synthesis Example 1 above. And 4,4′-dihydroxybenzophenone (6.00 g (Aldrich reagent, 0.028 mol)), and after nitrogen substitution, after dissolving uniformly in 170 g of N-methyl-2-pyrrolidone (NMP) and 100 g of toluene, 24 g of potassium (Aldrich reagent, 0.18 mol) was added.

  Next, 31,16 g of 4,4′-difluorobenzophenone (Aldrich reagent, 0.14 mol), 30 g of NMP, and 60 g of toluene were added, and the mixture was heated with stirring to form an azeotrope of toluene and water at a reaction liquid temperature of 155 ° C. Dehydration was performed while refluxing. When the dehydration amount reached 1.3 g (dehydration rate 100% vs. stoichiometric value), 0.5 ml of the reaction solution was sampled and the molecular weight was measured. The weight average molecular weight was 10,000. In this step, the content of the diol monomer containing a hydrolyzable group in the diol monomers in this step is 80 mol%, and the diol monomer having an ionic group and the dihalide monomer having an ionic group The total content of was 0 mol%.

Step (9)
The disodium 3,3′-disulfonate-4,4 obtained in Synthesis Example 2 as a dihalide monomer having an ionic group was added to a 4 L reaction vessel equipped with a Dean-Stark trap with a stirrer, a nitrogen introduction tube, and a dropping funnel. '-Difluorobenzophenone 255.4 g (0.56 mol), NMP (1870 g) and 1,4,7,10,13,17-hexaoxacyclooctadecane 140 g were added and dissolved uniformly. Further, 46.85 g (0.112 mol) of disodium 3,3′-disulfonate-4,4′-dihydroxybenzophenone obtained in Synthesis Example 3 as a diol monomer having an ionic group in another container, NMP (340 g) Were uniformly dissolved and mixed. Further, 86.78 g (0.336 mol) of K-DHBP obtained in Synthesis Example 1 and 23.99 g of 4,4′-dihydroxybenzophenone (Wako Pure Chemical Reagent, 0.112 mol) were added, and 100 g of NMP and 140 g of toluene were added. After uniformly dissolving, 100 g of potassium carbonate (Aldrich reagent, 0.70 mol) was added. The dihalide monomer having an ionic group in this step is 100 mol% in the dihalide monomers, and the total content of the diol monomer having an ionic group and the dihalide monomer having an ionic group is 60.0 mol. %Met. This solution was heated with stirring, and dehydration was performed while refluxing an azeotrope of toluene and water at a reaction liquid temperature of 165 ° C. When the dehydration amount reached 5.1 g (dehydration rate 50% vs. stoichiometric value), 0.5 ml of the reaction solution was sampled and the molecular weight was measured. The weight average molecular weight was 5000.

Step (10)
The reaction solution of step (2) was transferred into the reaction vessel of step (1) with a tube pump and mixed uniformly, and then dehydration was continued at a reaction solution temperature of 160 ° C. When the total amount of dehydration exceeds 12.6 g (100% dehydration rate vs. stoichiometric value), a part of toluene is distilled off and the reaction solution temperature is raised to 175 ° C. and maintained until the generation of carbon dioxide gas is reduced. did.

Estimated reduction in carbon dioxide generation using Chino Corp. CO ₂ monitor MA1002-0P, the gas in the nitrogen line to be discharged from the reaction vessel was collected in 5cc syringe and injected into CO ₂ monitor, a carbon dioxide concentration When the value of atmospheric pressure was +200 ppm or less, the next process was started. Next, while distilling off toluene from the reaction vessel, the temperature of the reaction solution was raised to 200 ° C. and polymerization was continued. The change in the power consumption of the stirrer was confirmed with Watt Checker Model 2000MS1 manufactured by Measurement Technology Laboratory Co., Ltd., and the polymerization was stopped when the power consumption did not change for 30 minutes or more or a decreasing trend was observed for 10 minutes continuously. It was 160,000 when 0.5g was sampled from this reaction liquid and the molecular weight was measured. After completion of the polymerization, 1000 g of NMP was added and cooled to room temperature to obtain a polymerization stock solution E.

The subsequent steps were performed in the same manner as in Example 1 to obtain an electrolyte membrane E having a film thickness of 15 μm. The electrolyte membrane E had a sulfonic acid group density of 3.21 mmol / g. When this high-temperature low-humidification power generation evaluation was performed using this electrolyte membrane E, it was 720 mW / cm ² , and a dry-wet cycle test was performed 6800 times.

Comparative Example 1
Process (1)
99.18 g (0.38 mol) of K-DHBP, which is a diol monomer containing the hydrolyzable group obtained in Synthesis Example 1, was added to a 4000 mL reaction vessel equipped with a Dean-Stark trap with a stirrer, a nitrogen introduction tube and a dropping funnel. And 4,4′-dihydroxybenzophenone (20.57 g (Aldrich reagent, 0.096 mol)), and after nitrogen substitution, after dissolving uniformly in 240 g of N-methyl-2-pyrrolidone (NMP) and 140 g of toluene, 138 g of potassium (Aldrich reagent, 1 mol) was added.

  Next, 106.83 g of 4,4′-difluorobenzophenone (Aldrich reagent, 0.49 mol), 120 g of NMP, and 100 g of toluene were added, and the mixture was heated while stirring to form an azeotrope of toluene and water at a reaction liquid temperature of 155 ° C. Dehydration was performed while refluxing. When the dehydration amount reached 8.6 g (100% dehydration rate vs. stoichiometric value), 0.5 ml of the reaction solution was sampled and the molecular weight was measured. The weight average molecular weight was 6000. In this step, the content of the diol monomer containing a hydrolyzable group in the diol monomer in this step is 79.8 mol%, and the diol monomer having an ionic group and the divalent monomer having an ionic group are used. The total content of halide monomers was 0 mol%.

Process (2)
Next, 145.94 g (0.35 mol) of disodium 3,3′-disulfonate-4,4′-difluorobenzophenone obtained in Synthesis Example 2 as a dihalide monomer having an ionic group in another container, NMP (1070 g) ), 80 g of 1,4,7,10,13,17-hexaoxacyclooctadecane and uniformly dissolved, and then 66.12 g (0.26 mol) of K-DHBP obtained in Synthesis Example 1 and 4,4 13.71 g of '-dihydroxybenzophenone (Aldrich reagent, 0.063 mol) was added, 240 g of N-methyl-2-pyrrolidone (NMP) and 140 g of toluene were added and dissolved uniformly, and then a dropping funnel provided in the reaction vessel To replace with nitrogen. The dihalide having an ionic group in this step was 100 mol% in the dihalide, and the total content of the diol monomer having an ionic group and the dihalide monomer having an ionic group was 52 mol%.

When the amount of dehydration in step (1) reached 8.6 g, the entire amount was dropped from the dropping funnel at a rate of 100 g / min, and dehydration was continued at a reaction solution temperature of 160 ° C. When the total amount of dehydration exceeds 14.3 g (100% dehydration rate vs. stoichiometric value), a part of toluene is distilled off and the reaction solution temperature is raised to 175 ° C. and maintained until the generation of carbon dioxide gas is reduced. did. Estimated reduction in carbon dioxide generation using Chino Corp. CO ₂ monitor MA1002-0P, the gas in the nitrogen line to be discharged from the reaction vessel was collected in 5cc syringe and injected into CO ₂ monitor, a carbon dioxide concentration When the value of atmospheric pressure was +200 ppm or less, the next process was started. Next, while distilling off toluene from the reaction vessel, the temperature of the reaction solution was raised to 200 ° C. and polymerization was continued. The change in the power consumption of the stirrer was confirmed with Watt Checker Model 2000MS1 manufactured by Measurement Technology Laboratory Co., Ltd., and the polymerization was stopped when the power consumption did not change for 30 minutes or more or a decreasing trend was observed for 10 minutes continuously. It was 250,000 when 0.5g was sampled from this reaction liquid and the molecular weight was measured. After completion of the polymerization, 1000 g of NMP was added and cooled to room temperature to obtain a polymerization stock solution A.

Step (3)
The polymerization stock solution A was set in an inverter / compact high-speed cooling centrifuge model 6930 manufactured by Kubota Seisakusho, an angle rotor RA-800, and solid-liquid separation was performed at 25 ° C. for 30 minutes with a centrifugal force of 20000 G. Since the cake and the supernatant liquid (coating liquid) could be separated cleanly, the supernatant liquid was recovered. Only the supernatant was pressure filtered through a 5 μm polytetrafluoroethylene (PTFE) filter and transferred to a separable flask. Next, it distilled under reduced pressure at 80 degreeC, stirring, NMP was removed until the viscosity of the supernatant liquid became 10 Pa.s, and the coating liquid A was obtained.

Process (4)
A 125 μm PET film (“Lumirror (registered trademark)” manufactured by Toray Industries, Inc.) was used as a substrate, and the coating liquid A was cast by a slit die and dried at 150 ° C. for 15 minutes.

Step (5)
Next, the dried film is peeled off from PET and immersed in pure water at 25 ° C. for 10 minutes to leave residual salt, residual monomer, residual potassium carbonate, residual NMP, residual 1,4,7,10,13,17-hexaoxacyclooctadecane. And the like, and then immersed in 10% by weight sulfuric acid at 60 ° C. for 30 minutes to hydrolyze hydrolyzable groups and proton exchange of metal salts of sulfonic acid groups. Next, this membrane was washed with pure water until the washing solution became neutral and dried at 60 ° C. for 30 minutes to obtain an electrolyte membrane A having a thickness of 15 μm. The electrolyte membrane A had a sulfonic acid group density of 2.90 mmol / g. When this high-temperature low-humidification power generation evaluation was performed using this electrolyte membrane A, it was 500 mW / cm ² , and a dry-wet cycle test was performed 10,000 times.

Comparative Example 2
The same procedure as in Example 1 was performed except that the steps (1) and (2) in Example 1 were changed as follows.

Process (1)
The disodium 3,3′-disulfonate-4,4 obtained in Synthesis Example 2 as a dihalide monomer having an ionic group was added to a 4 L reaction vessel equipped with a Dean-Stark trap with a stirrer, a nitrogen introduction tube, and a dropping funnel. '-Difluorobenzophenone 180.91 g (0.43 mol), 4,4'-difluorobenzophenone 10.0 g (Aldrich reagent, 0.046 mol), NMP (1350 g), 1,4,7,10,13,17-hexa After 100 g of oxacyclooctadecane was added and uniformly dissolved, 65.08 g (0.25 mol) of K-DHBP obtained in Synthesis Example 1 and 31.28 g of 4,4′-biphenol (Wako Pure Chemical Reagent, 0.17 mol) were obtained. ), Add 210 g of NMP and 290 g of toluene, dissolve uniformly, and then 120 g of potassium carbonate (Aldrich Reagent) 0.87mol) was added. The dihalide monomer having an ionic group in this step is 90.3 mol% in the dihalides, and the total content of the diol monomer having an ionic group and the dihalide monomer having an ionic group is 48.0 mol. %Met.
This solution was heated with stirring, and dehydration was performed while refluxing an azeotrope of toluene and water at a reaction liquid temperature of 165 ° C. When the dehydration amount reached 7.6 g (dehydration rate 100% vs. stoichiometric value), 0.5 ml of the reaction solution was sampled and the molecular weight was measured. The weight average molecular weight was 9000.

Process (2)
Next, in a separate container, 43.39 g (0.17 mol) of K-DHBP, which is the diol monomer containing the hydrolyzable group obtained in Synthesis Example 1, 24.0 g of 4,4′-dihydroxybenzophenone (Aldrich reagent, 0 .11 mol), 4,4′-difluorobenzophenone 52.32 g (Aldrich reagent, 0.24 mol), NMP 720 g, and toluene 130 g, and uniformly dissolved, charged in a dropping funnel equipped in the reaction vessel, and replaced with nitrogen did.
The content of the diol monomer containing a hydrolyzable group in the diol monomers in this step is 60.7 mol%, and the total content of the diol monomer having an ionic group and the dihalide monomer having an ionic group Was 0 mol%.

  When the amount of dehydration in step (1) reached 7.6 g, the entire amount was dropped from the dropping funnel at a rate of 100 g / min, and dehydration was continued at a reaction solution temperature of 160 ° C. When the total amount of dehydration exceeds 12.6 g (100% dehydration rate vs. stoichiometric value), a part of toluene is distilled off and the reaction solution temperature is raised to 175 ° C. and maintained until the generation of carbon dioxide gas is reduced. did.

Estimated reduction in carbon dioxide generation using Chino Corp. CO ₂ monitor MA1002-0P, the gas in the nitrogen line to be discharged from the reaction vessel was collected in 5cc syringe and injected into CO ₂ monitor, a carbon dioxide concentration When the value of atmospheric pressure was +200 ppm or less, the next process was started. Next, while distilling off toluene from the reaction vessel, the temperature of the reaction solution was raised to 200 ° C. and polymerization was continued. The change in the power consumption of the stirrer was confirmed with Watt Checker Model 2000MS1 manufactured by Measurement Technology Laboratory Co., Ltd., and the polymerization was stopped when the power consumption did not change for 30 minutes or more or a decreasing trend was observed for 10 minutes continuously. It was 200,000 when 0.5g was sampled from this reaction liquid and the molecular weight was measured. After completion of the polymerization, 1000 g of NMP was added and cooled to room temperature to obtain a polymerization stock solution D.

The subsequent steps were performed in the same manner as in Example 1 to obtain an electrolyte membrane D having a film thickness of 15 μm. The electrolyte membrane D had a sulfonic acid group density of 2.92 mmol / g. When this high-temperature low-humidification power generation evaluation was performed using this electrolyte membrane D, it was 610 mW / cm ² , and the dry-wet cycle test was performed 7500 times.

Comparative Example 3
Process (1)
A stirrer, a nitrogen introducing tube, and a dropping funnel were added to a 4000 mL reaction vessel equipped with a Dean-Stark trap, and K-DHBP 11.62 g (0.045 mol) which is a diol monomer containing a hydrolyzable group obtained in Synthesis Example 1 above. , And 4,4′-dihydroxybenzophenone (Aldrich reagent, 0.135 mol), and after nitrogen substitution, the solution was uniformly dissolved in 260 g of N-methyl-2-pyrrolidone (NMP) and 40 g of toluene. Potassium 31 g (Aldrich reagent, 1 mol) was added.

  Next, 40.06 g of 4,4′-difluorobenzophenone (Aldrich reagent, 0.18 mol), 190 g of NMP, and 40 g of toluene were added, and the mixture was heated while stirring to form an azeotrope of toluene and water at a reaction liquid temperature of 155 ° C. Dehydration was performed while refluxing. When the dehydration amount reached 3.2 g (dehydration rate 100% vs. stoichiometric value), 0.5 ml of the reaction solution was sampled and the molecular weight was measured. The weight average molecular weight was 10,000. In this step, the content of the diol monomer containing a hydrolyzable group in the diol monomer in this step is 25 mol%, and the diol monomer having an ionic group and the dihalide monomer having an ionic group The total content of was 0 mol%.

Process (2)
The disodium 3,3′-disulfonate-4,4 obtained in Synthesis Example 2 as a dihalide monomer having an ionic group was added to a 4 L reaction vessel equipped with a Dean-Stark trap with a stirrer, a nitrogen introduction tube, and a dropping funnel. '-Difluorobenzophenone 191.55 g (0.45 mol), NMP (1400 g), 1,4,7,10,13,17-hexaoxacyclooctadecane 105 g were added and dissolved uniformly, and then obtained in Synthesis Example 1 above. 86.78 g (0.34 mol) of K-DHBP and 17.99 g of 4,4′-dihydroxybenzophenone (Wako Pure Chemical Reagent, 0.084 mol) were added, and 210 g of NMP and 300 g of toluene were added and dissolved uniformly. 120 g of potassium (Aldrich reagent, 0.87 mol) was added. The dihalide monomer having an ionic group in this step is 100 mol% in dihalides, and the total content of the diol monomer having an ionic group and the dihalide monomer having an ionic group is 51.0 mol%. there were. This solution was heated with stirring, and dehydration was performed while refluxing an azeotrope of toluene and water at a reaction liquid temperature of 165 ° C. When the dehydration amount reached 3.8 g (dehydration rate 50% vs. stoichiometric value), 0.5 ml of the reaction solution was sampled and the molecular weight was measured. The weight average molecular weight was 5000.

Step (3)
The reaction solution of step (2) was transferred into the reaction vessel of step (1) with a tube pump and mixed uniformly, and then dehydration was continued at a reaction solution temperature of 160 ° C. When the total amount of dehydration exceeds 10.8 g (dehydration rate 100% vs. stoichiometric value), a part of toluene is distilled off and the reaction liquid temperature is raised to 175 ° C. and maintained until the generation of carbon dioxide gas decreases. did.

Estimated reduction in carbon dioxide generation using Chino Corp. CO ₂ monitor MA1002-0P, the gas in the nitrogen line to be discharged from the reaction vessel was collected in 5cc syringe and injected into CO ₂ monitor, a carbon dioxide concentration When the value of atmospheric pressure was +200 ppm or less, the next process was started. Next, while distilling off toluene from the reaction vessel, the temperature of the reaction solution was raised to 200 ° C. and polymerization was continued. The change in the power consumption of the stirrer was confirmed with Watt Checker Model 2000MS1 manufactured by Measurement Technology Laboratory Co., Ltd., and the polymerization was stopped when the power consumption did not change for 30 minutes or more or a decreasing trend was observed for 10 minutes continuously. It was 180,000 when 0.5g was sampled from this reaction liquid and the molecular weight was measured. After completion of the polymerization, 1000 g of NMP was added and cooled to room temperature to obtain a polymerization stock solution E.

The subsequent steps were performed in the same manner as in Example 1 to obtain an electrolyte membrane E having a film thickness of 15 μm. The electrolyte membrane E had a sulfonic acid group density of 3.01 mmol / g. When this electrolyte membrane E was used and high temperature low humidification power generation evaluation was carried out, it was 640 mW / cm < ² >, and when the dry and wet cycle test was implemented, it was 7000 times.

  The method for producing an electrolyte membrane of the present invention can produce an electrolyte membrane excellent in the balance between power generation characteristics and durability under low humidification at a high quality and at low cost, and the obtained electrolyte membrane can be produced by various electrochemical devices (for example, The present invention can be applied to fuel cells, water electrolyzers, chloroalkali electrolyzers, and the like. Among these devices, it is suitable for a fuel cell, particularly suitable for a fuel cell using hydrogen or a methanol aqueous solution as a fuel, a mobile phone, a personal computer, a PDA, a video camera (camcorder), a digital camera, a handy terminal, an RFID reader. , Digital audio players, portable devices such as various displays, electric shavers, household appliances such as vacuum cleaners, electric tools, household power supply machines, cars such as passenger cars, buses and trucks, motorcycles, bicycles with electric assist, electric carts, It is preferably used as a power supply source for mobile bodies such as electric wheelchairs, ships and railways, various robots, and cyborgs. Especially in portable devices, it is used not only for power supply sources, but also for charging secondary batteries installed in portable devices, and also suitable as a hybrid power supply source used in combination with secondary batteries, capacitors, and solar cells. Available to:

Claims (2)

A method for producing a polymer electrolyte membrane using as a precursor a membrane-like product comprising a polymer containing a hydrolyzable group and an ionic group, obtained by desalting polycondensation of diol monomers and dihalide monomers, A method for producing a polymer electrolyte membrane, comprising the following steps.
(1) A diol monomer containing 20 to 100 mol% of a diol monomer having a hydrolyzable group and a dihalide monomer, the total content of the diol monomer having an ionic group and the dihalide monomer having an ionic group is 0 Step of obtaining an electrolyte prepolymer solution by dissolving in a solvent and bringing it into contact with a basic compound so as to be ˜20 mol% (2) A diol containing 10 mol% or more of a diol monomer having an ionic group A dihalide monomer containing 20 to 100 mol% of a monomer and a dihalide monomer having an ionic group, a total content of a diol monomer having an ionic group and a dihalide monomer having an ionic group is the step (1). Including the total of diol monomer having ionic group and dihalide monomer having ionic group Step (3) Step (2) to obtain an electrolyte polymer solution by adding to the electrolyte prepolymer solution obtained in the step (1) and dehydrating by heating so that the amount value is 10 to 100 mol%. The subsequent electrolyte polymer solution is subjected to solid-liquid separation by direct centrifugal separation to form a coating solution (4) The coating solution after the step (3) is cast-coated on a substrate, and the solvent is evaporated by heating. (5) The step of using the membrane as a precursor and bringing it into contact with an acidic aqueous solution to form a polymer electrolyte membrane The method for producing a polymer electrolyte membrane according to claim 1, wherein the diol monomer having an ionic group described in step (2) is represented by the following general formula (P1):