JP2011040370A - Polymer electrolyte material, and manufacturing method of polymer electrolyte membrane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a polymer electrolyte material having excellent proton conductivity under a low humidification condition which enables a solid polymer fuel cell to have a long term power generation durability when the solid polymer fuel cell employs this polymer electrolyte material, and to provide a method of manufacturing polymer electrolyte membrane using this polymer electrolyte material. <P>SOLUTION: In the manufacturing method of the polymer electrolyte material wherein at least two kinds of polymer A and polymer B of different ionic group densities are blended, at least the polymer A is aromatic polyether ketone having hydrolyzable group, and they are blended so that, when ionic group density of polymer A is denoted by X, ionic group density of polymer B is denoted by Y and ionic group density after blending is denoted by Z, X is 1.5 mmol/g or less, Y is X+0.5 mmol/g or more, and Z is X+0.2 mmol/g or more. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is a polymer electrolyte fuel cell that has excellent proton conductivity even under low humidification conditions, and is excellent in practicality that can achieve excellent mechanical strength, fuel cutoff and long-term durability. The present invention relates to a polymer electrolyte material and a 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. Because of the crystallinity, a polymer having a low sulfonic acid group density composition is insoluble in a solvent due to the remaining crystals, resulting in poor processability. Conversely, if the sulfonic acid group density is increased to improve processability, Since the polymer was not crystalline, it swelled remarkably in water, and not only the fuel crossover of the prepared membrane was large, but also the strength of the prepared membrane was insufficient.

  Here, a polymer electrolyte membrane made of a blend of aromatic polyetherketone, polysulfone and a hydrophilic polymer has been reported (Patent Document 3). However, the ionic group density was not sufficiently controlled, and the mechanical strength and physical durability were not satisfactory.

  As described above, the polymer electrolyte material according to the prior art is insufficient as a means for improving economy, workability, proton conductivity, fuel crossover, mechanical strength, and long-term durability, and is an industrially useful fuel cell. It could not be a polymer electrolyte material for use.

JP-A-6-93114 Japanese translation of PCT publication No. 2004-528683 JP-A-8-20716

  In light of the background of the prior art, the present invention provides a polymer electrolyte that has excellent proton conductivity under low humidification conditions and can achieve long-term power generation durability when a solid polymer fuel cell is obtained. It is intended to provide a material and a method for producing a polymer electrolyte membrane.

  The present invention employs the following means in order to solve such problems. That is, the method for producing the polymer electrolyte material and the polymer electrolyte membrane of the present invention is as follows.

  A method for producing a polyelectrolyte material comprising blending at least two types of polymers A and B having different ionic group densities, wherein at least polymer A is an aromatic polyetherketone having a hydrolyzable group, When the ionic group density is X, the ionic group density of polymer B is Y, and the ionic group density after blending is Z, X is 1.5 mmol / g or less, Y is X + 0.5 mmol / g or more, Z is A method for producing an aromatic polyetherketone polymer electrolyte material, wherein blending is performed so that X + 0.2 mmol / g or more

  According to the present invention, in a polymer electrolyte fuel cell, a polymer electrolyte material having excellent proton conductivity under low humidification conditions and capable of achieving long-term power generation durability, as well as it A high-performance polymer electrolyte membrane using can be provided.

Results of high-temperature low-humidification power generation evaluation and durability evaluation based on the number of wet and dry cycles

  Hereinafter, the present invention will be described in detail first. The present invention has been intensively studied on the above-mentioned problem, that is, a method for producing an industrially useful polyelectrolyte polymer excellent in economic efficiency and processability, and blending at least two polymers having different ionic group densities. , It has been clarified that such problems can be solved all at once.

  When conventional sulfonated aromatic polyether ketone or sulfonated aromatic polyethersulfone is used as a polymer electrolyte material, the membrane swells when the content of ionic groups is increased to increase proton conductivity, There was a problem that the fuel crossover of methanol or the like was large, and a problem that the mechanical strength of the membrane and the stability of the higher order structure were insufficient due to the low cohesion of the polymer molecular chains. On the other hand, the method for producing a polymer electrolyte material of the present invention has found that power generation performance at low humidification can be improved while blending at least two kinds of polymers having different ion exchange capacities while suppressing a decrease in durability. It was.

  The polymer used in the present invention includes at least polymer A and polymer B having different ionic group densities, and may include three or more types of polymers.

  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.

  The method for introducing an ionic group into the polymer used in the method for producing an electrolyte membrane of the present invention includes a method of polymerizing using a monomer having an ionic group and a method of introducing an ionic group by a polymer reaction. can give.

  As a polymerization method using a monomer having an ionic group, a monomer having an ionic group in a repeating unit may be used. Similarly, the method for introducing a hydrolyzable group may be carried out using a monomer having a hydrolyzable group in the repeating unit.

  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 ionic group density X of the polymer A to which the method for producing an electrolyte membrane of the present invention can be applied needs to be 1.5 mmol / g or less from the viewpoint of mechanical strength and long-term durability. In addition, the ionic group density Y of the polymer B needs to be X + 0.5 mmol / g, preferably 2.1 mmol / g or more, from the viewpoint of proton conductivity and power generation performance at low humidification. Further, by setting the ionic group density Z of the polymer after blending to X + 0.2 mmol / g, proton conductivity and power generation performance at low humidification can be maintained.

  The polymer A used in the present invention will be described. The polymer A needs to be an aromatic polyether ketone having a hydrolyzable group from the viewpoints of mechanical strength, physical durability and chemical stability. In the method for producing an electrolyte membrane of the present invention, a polymer containing a hydrolyzable group is used as a precursor. The hydrolyzable group in the present invention is a solvent when no hydrolyzable group is introduced. It is a substituent for the purpose of imparting solubility that is temporarily introduced so that solution casting or filtration can be easily performed on the assumption that it is introduced into a polymer that is difficult to dissolve and then removed by hydrolysis in a later step. In the present invention, the aromatic polyether ketone includes a precursor having a hydrolyzable group.

  The hydrolyzable group can be appropriately selected in consideration of reactivity, yield, stability of the hydrolyzable group-containing state, production cost, and the like. In addition, the stage for introducing the hydrolyzable group in the polymerization reaction may be selected from the monomer stage, the oligomer stage, or the polymer stage, and can be selected as appropriate. From the viewpoint of productivity, it is introduced at the monomer stage. It is preferable to do this.

  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 method for producing an electrolyte membrane of the present invention, the structural unit containing a hydrolyzable group preferably contains at least one selected from the following general formulas (P1) and (P2).

(In the formulas (P1) and (P2), 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 formulas (P1) and (P2) may be optionally substituted.)
Of these, the method in which E is O in the general formulas (P1) and (P2), 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 (P1) 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 (P2), 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 (P1) or (P2), those having at least the general formula (P2) are more preferably used from the viewpoint of stability such as hydrolysis resistance during the process and solubility in a solvent. It is done. Furthermore, R _{3 in the} general formula (P2) 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 (P1) and (P2) 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 (P2) 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.

  Preferred examples of the monomer applied to the method for producing an electrolyte membrane of the present invention having a hydrolyzable group are represented by the following general formulas (P1-1) and (P2-1) as aromatic dihydroxy compounds, respectively. And can be synthesized by an aromatic nucleophilic substitution reaction with an aromatic active dihalide compound. The monomer having a hydrolyzable group may be derived from either the aromatic dihydroxy compound or the aromatic active dihalide compound as the structural unit represented by the general formulas (P1) and (P2). Thus, it is more preferable to derive from an aromatic dihydroxy compound.

(In the general formula (P1-1) and (P2-1), 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 (P1-1) and the general formula (P2-1) may be optionally substituted.
Next, the polymer B used in the present invention will be described. The polymer B applicable to the method for producing an electrolyte membrane in the present invention is preferably a polymer having an aromatic ring in the main chain among hydrocarbon polymers from the viewpoint of mechanical strength, physical durability and chemical stability. That is, a polymer having an aromatic ring in the main chain and having an ionic group is more preferable. Furthermore, what has a hydrolysable group is still more preferable. The ionic group of the present invention is not particularly limited as long as it is an atomic group having a negative charge, but preferably has a proton exchange ability. 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.

  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 good solvent used in the polymerization of the present invention is not particularly limited as long as it is a good solvent for the electrolyte polymer and can increase the molecular weight of the electrolyte polymer during polymerization. More preferred specific examples include N, N-dimethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, sulfolane, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphontri Examples include, but are not limited to, aprotic polar solvents such as amides. These organic solvents may be used alone or as a mixture of two or more.

  In the present invention, as a method of blending at least two kinds of polymers, the respective solutions are mixed in a state in which each polymer is diluted with a good solvent and made uniform.

  In addition, as a base material on which the polymer solution is applied, generally known materials can be used, but endless belts or drums made of metal such as stainless steel, films made of polymers such as polyethylene phthalate, polyimide and polysulfone, glass plates, release papers. Etc. 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.

  In addition, although there is no restriction | limiting in particular as a film thickness of an electrolyte membrane precursor, Usually, the 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, the process which uses the said film-like substance as a precursor and makes it contact with acidic aqueous solution to make 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 use of the polymer electrolyte molded body and the polymer electrolyte fuel cell using the polymer electrolyte material obtained by the present invention is not particularly limited, but a power supply source for a mobile body is preferable. In particular, mobile devices such as mobile phones, personal computers, PDAs, televisions, radios, music players, game machines, headsets, DVD players, human-type and animal-type robots for industrial use, home appliances such as cordless vacuum cleaners, and toys , Electric bicycles, motorcycles, automobiles, buses, trucks and other vehicles and ships, power supplies for mobiles such as railways, stationary primary generators such as stationary generators, or alternatives to these It is preferably used as a hybrid power source.

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

(1) 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) Dry and wet cycle test The dry and 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.

(4) 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 becomes 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
Disodium 3,3′-disulfonate-4,4′-difluorobenzophenone having an ionic group represented by the following general formula (G1) was synthesized.

109.1 g (Aldrich reagent) of 4,4′-difluorobenzophenone was reacted at 150 ° C. for 10 hours in 150 mL of fuming sulfuric acid (50 wt% SO ₃ ) (Wako Pure Chemicals reagent). Thereafter, the mixture was poured little by little into a large amount of water, neutralized with NaOH, and 200 g of sodium chloride was added to precipitate the composite. The resulting precipitate was filtered off and recrystallized with an aqueous ethanol solution to obtain disodium 3,3′-disulfonate-4,4′-difluorobenzophenone represented by the above general formula (G1). The purity was 99.3%. The structure was confirmed by ¹ H-NMR. Impurities were quantitatively analyzed by capillary electrophoresis (organic matter) and ion chromatography (inorganic matter).

Synthesis example 2
2,2-bis (4-hydroxyphenyl) -1,3-dioxolane having a hydrolyzable group represented by the following general formula (G2) was synthesized.

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

Synthesis Example 3 Synthesis of S0 Polymer An S0 polymer represented by the following general formula (G3) was synthesized.

  6.91 g of potassium carbonate, 10.3 g of 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane having a hydrolyzable group obtained in Synthesis Example 2 above, 8.73 g of 4,4′-difluorobenzophenone Was used for polymerization at 210 ° C. in N-methylpyrrolidone (NMP). The weight average molecular weight was 250,000.

Synthesis Example 4 Synthesis of S30 Polymer An S30 polymer represented by the following general formula (G4) was synthesized.

  6.91 g of potassium carbonate, 5.47 g of disodium 3,3′-disulfonate-4,4′-difluorobenzophenone having an ionic group obtained in Synthesis Example 1, and the hydrolyzable group obtained in Synthesis Example 2 Polymerization was carried out at 210 ° C. in N-methylpyrrolidone (NMP) using 10.3 g of 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane having 6.11 g of 4,4′-difluorobenzophenone. went. The weight average molecular weight was 300,000.

Synthesis Example 5 Synthesis of S40 Polymer An S40 polymer represented by the following general formula (G5) was synthesized.

  6.91 g of potassium carbonate, 7.30 g of disodium 3,3′-disulfonate-4,4′-difluorobenzophenone having the ionic group obtained in Synthesis Example 1, and the hydrolyzable group obtained in Synthesis Example 2 Polymerization was carried out at 210 ° C. in N-methylpyrrolidone (NMP) using 10.3 g of 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane and 5.24 g of 4,4′-difluorobenzophenone. went. The weight average molecular weight was 320,000.

Synthesis Example 6 Synthesis of S50 Polymer An S50 polymer represented by the following general formula (G6) was synthesized.

  6.91 g of potassium carbonate, 9.12 g of disodium 3,3′-disulfonate-4,4′-difluorobenzophenone having the ionic group obtained in Synthesis Example 1, and the hydrolyzable group obtained in Synthesis Example 2 Polymerization at 210 ° C. in N-methylpyrrolidone (NMP) using 10.3 g of 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane and 4.36 g of 4,4′-difluorobenzophenone went. The weight average molecular weight was 270,000.

Synthesis Example 7 Synthesis of S60 Polymer An S60 polymer represented by the following general formula (G7) was synthesized.

  6.91 g of potassium carbonate, 11.0 g of disodium 3,3′-disulfonate-4,4′-difluorobenzophenone having an ionic group obtained in Synthesis Example 1, and the hydrolyzable group obtained in Synthesis Example 2 Polymerization at 210 ° C. in N-methylpyrrolidone (NMP) using 10.3 g of 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane and 3.49 g of 4,4′-difluorobenzophenone went. The weight average molecular weight was 280,000.

Synthesis Example 8 Synthesis of S100 Polymer An S100 polymer represented by the following general formula (G8) was synthesized.

  6.91 g of potassium carbonate, 18.2 g of disodium 3,3′-disulfonate-4,4′-difluorobenzophenone having the ionic group obtained in Synthesis Example 1, and the hydrolyzable group obtained in Synthesis Example 2 Polymerization was performed at 210 ° C. in N-methylpyrrolidone (NMP) using 10.3 g of 2,2-bis (4-hydroxyphenyl) -1,3-dioxolane having the following formula. The weight average molecular weight was 290,000.

Comparative Example 1 Polymer Electrolyte Membrane Only of S0 Polymer The polymerization stock solution of S0 polymer prepared by the method described in Synthesis Example 3 was diluted with 90 g of NMP, and the diluted polymerization stock solution was converted into an inverter / compact high-speed cooling centrifuge manufactured by Kubota Corporation Model No. 6930 An angle rotor RA-800 was set, and solid-liquid separation was performed at 25 ° C. for 30 minutes with a centrifugal force of 20000 G. Since the cake and supernatant liquid (coating liquid) could be separated cleanly, it was designated as coating liquid C. The obtained coating liquid C was cast on a glass substrate to obtain a polymer electrolyte membrane. Furthermore, after drying at 100 ° C. for 4 hours, heat treatment was performed at 350 ° C. for 10 minutes under nitrogen to obtain a polymer electrolyte membrane. This was immersed in 10% sulfuric acid at 60 ° C. for 1 hour for proton substitution, and then immersed in a large excess amount of pure water for 24 hours for sufficient washing.

  Table 1 shows the results of durability evaluation based on ion exchange capacity (ionic group density), high-temperature and low-humidity power generation evaluation, and the number of dry and wet cycles of the obtained polymer electrolyte membrane. The high temperature and low humidification power generation evaluation and the durability evaluation by the number of wet and dry cycles could not be performed.

Comparative Examples 2-6 Polymer Electrolyte Membrane with S30, S40, S50, S60, S100 Polymers Only Polymer electrolytes were prepared in the same manner as in Comparative Example 1, using the polymer polymerization stock solutions prepared by the methods described in Synthesis Examples 4-7. A membrane was obtained. The results of the durability evaluation based on the ion exchange capacity (ionic group density), the high-temperature and low-humidity power generation evaluation, and the number of dry and wet cycles of the obtained polymer electrolyte membrane are as shown in Table 1 and FIG. In Comparative Example 2, the high temperature low humidification power generation evaluation and the durability evaluation by the number of dry and wet cycles could not be performed.

Examples 1-6, Comparative Examples 7-9 Polymer electrolyte membranes blended with polymers Polymerization stock solutions prepared by the methods described in Synthesis Examples 3-8 were used as coating solutions in accordance with the methods described in Comparative Example 1, respectively. . This coating solution was mixed at various weight ratios. The mixed coating solution was cast on a glass substrate to obtain a polymer electrolyte membrane. Furthermore, after drying at 100 ° C. for 4 hours, heat treatment was performed at 350 ° C. for 10 minutes under nitrogen to obtain a polymer electrolyte membrane. This was immersed in 10% sulfuric acid at 60 ° C. for 1 hour for proton substitution, and then immersed in a large excess amount of pure water for 24 hours for sufficient washing.

Table 1 and FIG. 1 show the results of durability evaluation based on the blend ratio, ion exchange capacity (ionic group density), high-temperature and low-humidity power generation evaluation, and the number of wet and dry cycles of the obtained polymer electrolyte membrane. In Comparative Examples 8 and 9, high temperature and low humidification power generation evaluation and durability evaluation by the number of dry and wet cycles could not be performed. In Comparative Example 7, the high-temperature and low-humidification power generation evaluation was 600 mW / cm ² , and the durability evaluation by the dry / wet cycle was 100 times, and the performance was remarkably poor as compared with Examples 1-6.

Comparative Example 10 Polysulfone and S100 Polymer Blend Polymer Electrolyte Membrane
The S100 polymer prepared by the method described in Synthesis Example 8 was used as a coating solution according to the method described in Comparative Example 1. Separately, 50 g of polysulfone (Aldrich) was dissolved in 200 g of NMP to obtain a coating solution E. The ionic group density of this polysulfone was 0 mmol / g. Ion The coating liquids D and E were mixed at a weight ratio of 5: 5. The mixed coating solution was cast on a glass substrate to obtain a polymer electrolyte membrane. Furthermore, after drying at 100 ° C. for 4 hours, heat treatment was performed at 350 ° C. for 10 minutes under nitrogen to obtain a polymer electrolyte membrane. This was immersed in 10% sulfuric acid at 60 ° C. for 1 hour for proton substitution, and then immersed in a large excess amount of pure water for 24 hours for sufficient washing.

The results of durability evaluation based on the blending ratio of the obtained polymer electrolyte membrane, evaluation of high-temperature and low-humidity power generation, and the number of dry and wet cycles are as shown in Table 2 and FIG. The high-temperature low-humidification power generation evaluation was 520 mW / cm ² , and the durability evaluation by the dry / wet cycle was 50 times, and the performance was remarkably poor as compared with Examples 1-6.

  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 polyelectrolyte material comprising blending at least two types of polymers A and B having different ionic group densities, wherein at least polymer A is an aromatic polyetherketone having a hydrolyzable group, When the ionic group density is X, the ionic group density of polymer B is Y, and the ionic group density after blending is Z, X is 1.5 mmol / g or less, Y is X + 0.5 mmol / g or more, Z is A method for producing an aromatic polyetherketone polymer electrolyte material, wherein blending is performed so that X + 0.2 mmol / g or more   A solution of a polymer electrolyte material produced by the method for producing a polymer electrolyte material according to claim 1 is cast-coated on a base material, and the solvent is heated and evaporated to obtain a film-like material. A process for producing an aromatic polyetherketone polymer electrolyte membrane, comprising the step of bringing a polymer into contact with an acidic aqueous solution

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