JP5204971B2 - Method for producing polymer electrolyte membrane, polymer electrolyte membrane produced by the production method, and use thereof - Google Patents

Description

  The present invention relates to a method for producing a polymer electrolyte membrane, a polymer electrolyte membrane produced by the production method, and use thereof. In particular, a method for producing a polymer electrolyte membrane used for a solid polymer fuel cell, a direct liquid fuel cell, a direct methanol fuel cell, etc., a polymer electrolyte membrane produced by the production method, and the polymer electrolyte membrane The present invention relates to the use of the used membrane-electrode assembly and fuel cell.

  In recent years, development of highly efficient and clean energy sources has been demanded from the viewpoint of environmental problems such as global warming. Fuel cells are attracting attention as one candidate for this. A fuel cell directly supplies power by supplying a fuel such as hydrogen gas or methanol and an oxidant such as oxygen to electrodes separated by an electrolyte, while oxidizing the fuel on the one hand and reducing the oxidant on the other. is there.

  Among the fuel cell materials described above, one of the most important members is an electrolyte. Various electrolytes have been developed so far to separate such a fuel and an oxidant, but in recent years, an electrolyte composed of a polymer compound containing a proton conductive functional group such as a sulfonic acid group is particularly high. Molecular electrolytes are actively developed. Such polymer electrolytes can be used as raw materials for electrochemical elements such as humidity sensors, gas sensors, and electrochromic display elements, in addition to solid polymer fuel cells, direct liquid fuel cells, and direct methanol fuel cells. used.

  Among these polymer electrolyte utilization methods, solid polymer fuel cells, direct liquid fuel cells, and direct methanol fuel cells are expected as one of the pillars of new energy technology. For example, a polymer electrolyte fuel cell using an electrolyte membrane made of a polymer compound having a proton-conducting functional group has features such as operation at a low temperature and reduction in size and weight. Application to consumer cogeneration systems and consumer small portable devices is under consideration. Direct liquid fuel cells, especially direct methanol fuel cells that use methanol directly as fuel, have features such as a simple structure, ease of fuel supply and maintenance, and high energy density. As an alternative to lithium-ion secondary batteries, it is expected to be applied to small consumer portable devices such as mobile phones and laptop computers.

  Here, as the electrolyte membrane used in the polymer electrolyte fuel cell, there is a styrene-based cation exchange membrane developed in the 1950s, but it has poor stability in the fuel cell operating environment and has a sufficient life. No fuel cell has been produced.

  On the other hand, as an electrolyte membrane having practical stability, a perfluorocarbon sulfonic acid membrane represented by Nafion (registered trademark) has been widely studied. Perfluorocarbon sulfonic acid membranes are said to have high proton conductivity and excellent chemical stability such as acid resistance and oxidation resistance.

  However, since Nafion (registered trademark) is a fluorine-based electrolyte membrane, the raw material used is high, and a complicated manufacturing process is required, so that it is very expensive. It has also been pointed out that it is deteriorated by hydrogen peroxide generated by electrode reaction and by-product hydroxy radical. Further, the permeation (also referred to as crossover) of a hydrogen-containing liquid such as methanol which is a raw material of a direct liquid fuel cell is large, and so-called chemical short reaction occurs. As a result, cathode potential, fuel efficiency, cell characteristics and the like are lowered, and it is difficult to use as an electrolyte membrane of a direct liquid fuel cell such as a direct methanol fuel cell. Moreover, since Nafion (registered trademark) has a large morphological change, that is, swelling, the membrane itself is subjected to mechanical adaptability and may be damaged. Furthermore, since Nafion (registered trademark) has a high permeability such as a hydrogen-containing liquid, there is a concern that fuel may be lost due to crossover even when power is not generated.

  In order to solve the above problems, various polymer electrolyte membranes have been proposed. For example, Patent Document 1 proposes a sulfonic acid group-containing polyphenylene sulfide that is soluble in an aprotic polar solvent. It is disclosed that by introducing a sulfonic acid group under a homogeneous solution of polyphenylene sulfide in a chlorosulfonic acid solution, solubility in an aprotic polar solvent can be imparted, and the film can be easily processed. However, in the method disclosed herein, the solubility in methanol, which is being studied as a fuel for fuel cells, may also be imparted to the polymer electrolyte membrane at the same time, and the range of use of the polymer electrolyte membrane is significantly limited. There is a problem of being. In addition, there is no mention in this patent document about the effect of suppressing permeation (also referred to as crossover) of a hydrogen-containing liquid (such as methanol) of the polymer electrolyte membrane described in Patent Document 1, and the patent document In fact, the polymer electrolyte membrane described in 1) has a large swellability with respect to a hydrogen-containing liquid such as methanol which is a raw material of a direct liquid fuel cell, and has the same problem as that of Nafion (registered trademark).

Patent Document 2 discloses a method of filling a polymer porous support with an electrolyte monomer to increase the molecular weight of the monomer, and a polymer electrolyte membrane obtained by the method. Patent Document 3 discloses a method for introducing a sulfonic acid group into a polymer porous support that has been filled with an electrolyte monomer to increase the molecular weight, and a polymer electrolyte membrane obtained by the method. ing. These polymer electrolyte membranes are supposed to suppress the permeation (crossover) of them because the porous support supports the swelling with respect to methanol and water used as fuel. However, since the manufacturing process is complicated, the techniques disclosed in Patent Documents 2 and 3 have problems in terms of manufacturing cost and productivity. In addition, in order to develop sufficient proton conductivity in the polymer electrolyte membrane, it is necessary to increase the content of proton conductive groups in the electrolyte portion. The durability of this portion and the interface between the electrolyte and the support are required. There is a concern about the durability.
Japanese National Patent Publication No. 11-510198 (Publication date: September 7, 1999) International Publication No. 00/54351 Pamphlet (International Publication Date: September 14, 2000) Japanese Patent Laying-Open No. 2005-5171 (Publication date: January 6, 2005)

  As described above, development of a polymer electrolyte that suppresses permeation of fuel components such as a hydrogen-containing liquid while sufficiently ensuring proton conductivity is now strongly desired.

  The present invention has been made in view of the above problems, and its object is to ensure sufficient proton conductivity while suppressing the permeation of fuel components such as hydrogen-containing liquids, and to hydrogen-containing liquids such as methanol. By providing a method for producing a polymer electrolyte membrane with suppressed swelling and durability against a hydrogen-containing liquid such as methanol, a polymer electrolyte membrane produced by the production method, and a typical use example thereof is there.

As a result of intensive studies to solve the above problems, the present inventors have found that the general formula (1):
-CH ₂ OR ··· (1)
(In the formula, R represents hydrogen, an alkyl group or an acyl group, and R contained in one kind of compound may be the same or different.)
A polymer electrolyte membrane is obtained by impregnating a polymer film or a polymer electrolyte membrane in which a proton conductive group is introduced into a polymer film with at least one compound X containing two or more groups represented by Thus, while ensuring sufficient proton conductivity of the polymer electrolyte membrane, it is possible to suppress the permeation of fuel components such as a hydrogen-containing liquid, and to suppress swelling with respect to a hydrogen-containing liquid such as methanol. It has been found that durability against the contained liquid can be provided, and the present invention has been completed. The present invention has been completed based on such novel findings, and includes the following inventions.

That is, the method for producing a polymer electrolyte membrane according to the present invention includes:
In the method for producing a polymer electrolyte membrane including an introducing step of introducing a proton conductive group into the polymer film,
Before, after or simultaneously with the introduction step, at least one compound X containing two or more groups represented by the following general formula (1) is introduced into the polymer film or polymer film with a proton conductive group. A method for producing a polymer electrolyte membrane comprising an impregnation step of impregnating the polymer electrolyte membrane comprising:
-CH ₂ OR ··· (1)
(In the formula, R represents hydrogen, an alkyl group or an acyl group, and R contained in one kind of compound may be the same or different.)

  In the method for producing a polymer electrolyte membrane according to the present invention, at least one of the compounds X may be an aromatic compound derivative or a melamine derivative.

The method for producing a polymer electrolyte membrane according to the present invention includes:
At least one of the above compounds X may be 2,6-bis (hydroxymethyl) -para-cresol.

  In the method for producing a polymer electrolyte membrane according to the present invention, at least one of the compounds X may be a compound represented by the general formula (2).

(Wherein R _{1 to} R ₆ each represent hydrogen or a methyl group).

  By using the method for producing a polymer electrolyte membrane according to the present invention, as described later, while having sufficient proton conductivity, it has low methanol permeability and suppresses swelling with respect to a hydrogen-containing liquid such as methanol. Furthermore, it becomes possible to produce a polymer electrolyte membrane having durability against a hydrogen-containing liquid such as methanol.

  The method for producing a polymer electrolyte membrane according to the present invention may be a method in which an impregnation step is performed after the introduction step. According to the above aspect, after the polymer electrolyte membrane is preliminarily produced by introducing a proton conductive group into the polymer film, the polymer electrolyte membrane is impregnated with the desired physical properties. A polymer electrolyte membrane can be obtained more easily. Moreover, according to the said aspect, the merit that compound X becomes easy to impregnate with a polymer electrolyte membrane can be enjoyed.

  In the method for producing a polymer electrolyte membrane according to the present invention, the polymer film is preferably a polymer film containing a polymer compound having an aromatic unit. According to the said aspect, while being able to manufacture the polymer electrolyte membrane excellent in heat resistance and chemical stability, it can enjoy the effect that introduction | transduction of a proton conductive group is easy.

The method for producing a polymer electrolyte membrane according to the present invention includes:
The polymer film is
A polymer film containing (A) a polymer compound having an aromatic unit and (B) a polymer compound having no aromatic unit is preferable.

The method for producing a polymer electrolyte membrane according to the present invention includes:
The polymer electrolyte membrane is
A polymer electrolyte membrane in which a proton conductive group is introduced into a polymer film containing (A) a polymer compound having an aromatic unit, and (B) a polymer compound having no aromatic unit is preferable.
The said aspect manufactures a polymer electrolyte membrane using the polymer film containing the polymer compound which has an aromatic unit, and the polymer compound which does not have an aromatic unit. According to such an embodiment, it is possible to enjoy the effect that an electrolyte membrane with reduced methanol permeability and suppressed swelling with respect to a hydrogen-containing liquid such as methanol can be produced.

In the method for producing a polymer electrolyte membrane according to the present invention, (A) the polymer compound having an aromatic unit is one polymer selected from the following (i) to (iii), or these polymers: May be a mixture of:
(I) at least one polymer selected from the group of polymers consisting of polystyrene, syndiotactic polystyrene, polyphenylene ether, modified polyphenylene ether, polysulfone, polyethersulfone, polyetheretherketone, and polyphenylene sulfide;
(Ii) a copolymer comprising the polymer described in (i) above;
(Iii) Derivatives of the polymers described in (i) and (ii) above.
According to the above aspect, the polymer film and polymer electrolyte membrane to be obtained are excellent in processability and mechanical properties, and can be easily introduced with proton conductive groups. In addition, if an appropriate block copolymer, graft copolymer, acid-modified product, or the like is used, the compatibility with (B) the polymer compound having no aromatic unit and the dispersion state can be adjusted.

Furthermore, in the method for producing a polymer electrolyte membrane according to the present invention, the polymer compound having no aromatic unit (B) is selected from polymer compounds having a repeating unit of the following general formula (3) Or a mixture of these:
-(CX ₁ X ₂ -CX ₃ X ₄ )-(3)
_(Wherein, X _{1 to 4} is, H, based on any one _{of CH 3, Cl, F, OCOCH} 3, CN, COOH, are selected from the group consisting of COOCH _3, and _OC 4 _{H 9, X 1~ 4} are independent of each other and may be the same or different. According to the above aspect, a polymer electrolyte membrane having high chemical stability and excellent methanol barrier properties can be obtained.

  In the method for producing a polymer electrolyte membrane according to the present invention, the polymer compound (B) having no aromatic unit is selected from the group consisting of polyethylene, polypropylene, polymethylpentene, and derivatives thereof. It may be a seed polymer, or a mixture thereof. According to the above aspect, a polymer electrolyte membrane having high chemical stability and excellent methanol barrier properties can be obtained, and the effect that the polymer electrolyte membrane can be produced at low cost can be enjoyed.

  In the method for producing a polymer electrolyte membrane according to the present invention, the proton conductive group preferably includes a sulfonic acid group. When the polymer electrolyte membrane contains a sulfonic acid group as a proton conductive group, a polymer electrolyte membrane with further excellent proton conductivity can be obtained.

In addition, the method for producing a polymer electrolyte membrane according to the present invention is preferably a method including the following steps (I) and / or (II):
(I) a step of allowing a catalyst to coexist with the compound X during the impregnation step;
(II) A step of bringing the catalyst into contact with a polymer film or a polymer electrolyte membrane formed by introducing a proton conductive group into the polymer film after the impregnation step.

  According to the above aspect, since the binding between the compound X and the polymer film is promoted, the methanol permeability is reduced, and the swelling with respect to the hydrogen-containing liquid such as methanol is suppressed, and the hydrogen-containing liquid such as methanol is used. Thus, a polymer electrolyte membrane having durability against the above can be more efficiently produced.

  The method for producing a polymer electrolyte membrane according to the present invention includes a proton conductive group in the polymer film after the impregnation step and / or after the impregnation step, or the polymer film during the impregnation step and / or after the impregnation step. The method preferably includes a step of heating the introduced polymer electrolyte membrane. According to this aspect, since the binding between the compound X and the polymer film is promoted, the methanol permeability is reduced, and the swelling with respect to the hydrogen-containing liquid such as methanol is suppressed, and the hydrogen-containing liquid such as methanol is used. Thus, a polymer electrolyte membrane having durability against the above can be more efficiently produced.

On the other hand, the polymer electrolyte membrane according to the present invention is a polymer electrolyte membrane produced by the method for producing a polymer electrolyte membrane according to the present invention. The polymer electrolyte membrane according to the present invention is
(A) A polymer compound having an aromatic unit, and (B) a polymer film comprising a polymer compound having no aromatic unit and a proton conductive group introduced into the polymer electrolyte membrane, the following general formula (1 It may be a polymer electrolyte membrane characterized in that it contains at least one compound X containing two or more groups represented by
-CH ₂ OR ··· (1)
(In the formula, R represents hydrogen, an alkyl group or an acyl group, and R contained in one kind of compound may be the same or different.)

  The polymer electrolyte membrane according to the present invention is a polymer electrolyte membrane that has low methanol permeability, is suppressed from swelling with respect to a hydrogen-containing liquid such as methanol, and has durability against a hydrogen-containing liquid such as methanol. Therefore, it is excellent as a fuel cell material.

  Moreover, the membrane-electrode assembly according to the present invention uses the polymer electrolyte membrane according to the present invention. The membrane-electrode assembly according to the present invention includes a polymer electrolyte membrane having high methanol barrier properties and suppressed swelling with respect to a hydrogen-containing liquid such as methanol. It is particularly excellent as a membrane-electrode assembly for direct liquid fuel cells and direct methanol fuel cells.

  A fuel cell according to the present invention uses the polymer electrolyte membrane according to the present invention. The fuel cell according to the present invention is a fuel cell using a polymer electrolyte membrane obtained by the method for producing a polymer electrolyte membrane according to the present invention (solid polymer fuel cell, direct liquid fuel cell, direct methanol fuel). Battery etc.). Therefore, the fuel cell according to the present invention has a high methanol barrier property, and is suppressed from swelling with respect to a hydrogen-containing liquid such as methanol, and further has durability against a hydrogen-containing liquid such as methanol. It has excellent performance. In particular, the present invention is particularly preferably used for a polymer electrolyte fuel cell, a direct liquid fuel cell, and a direct methanol fuel cell.

  According to the present invention, by immersing the compound X in a polymer film or a polymer electrolyte membrane in which a proton conductive group is introduced into the polymer film, the methanol permeability is reduced as much as possible, and methanol or the like can be used. It is possible to produce a polymer electrolyte membrane that is suppressed from swelling with respect to a hydrogen-containing liquid or the like and that has durability against a hydrogen-containing liquid such as methanol. In addition to the above preferred physical properties, further processing can be achieved by using (A) a polymer compound having an aromatic unit and (B) a polymer film having no aromatic unit as the polymer film. It is possible to produce a polymer electrolyte membrane having excellent properties, mechanical properties, and chemical stability.

  Therefore, the present invention can be used in the field of fuel cells, and can be preferably used for solid polymer fuel cells, direct liquid fuel cells, direct methanol fuel cells and the like.

  An embodiment of the present invention will be described as follows. The present invention is not limited to the following description.

<1. Production Method for Polymer Electrolyte Membrane According to the Present Invention>
That is, the method for producing a polymer electrolyte membrane according to the present invention (hereinafter referred to as “the production method of the present invention”)
In the method for producing a polymer electrolyte membrane including an introducing step of introducing a proton conductive group into the polymer film,
Before, after or simultaneously with the introduction step, at least one compound X containing two or more groups represented by the following general formula (1) is introduced into the polymer film or polymer film with a proton conductive group. A method for producing a polymer electrolyte membrane comprising an impregnation step of impregnating the polymer electrolyte membrane comprising:
-CH ₂ OR ··· (1)
(In the formula, R represents hydrogen, an alkyl group or an acyl group, and R contained in one kind of compound may be the same or different.)
That is, the production method of the present invention is a method including at least an “introduction step” and an “impregnation step”. Hereafter, it demonstrates for every process. The production method of the present invention may include a “film formation step” for producing a polymer film.

(1-1) Impregnation Step “Compound X” used in the impregnation step in the production method of the present invention is at least one compound including two or more groups represented by the general formula (1). When the compound X includes two or more groups represented by the general formula (1), the compound X can have a plurality of bonds,
(a) Compound X binds to a polymer film (or polymer electrolyte membrane), and
(b) When the compounds X are bonded to each other, the compound X functions as a cross-linking agent, and a method for producing a polymer electrolyte membrane having a high methanol barrier property, which is one of the effects of the present invention, is possible. The “bond” between the compound X and the polymer film, the polymer electrolyte membrane, or the compound X is as long as the finally produced polymer electrolyte membrane has the desired physical properties of the present invention. It is not specifically limited, For example, it may be a chemical bond or a physical bond.

  In consideration of the reactivity at the time of bonding between the compounds X and the bonding between the compound X and the polymer film (or polymer electrolyte membrane), and the heat resistance in the bonded state, the compound X is an aromatic compound derivative. Or a melamine derivative. In consideration of the reactivity with the polymer film (or polymer electrolyte membrane), R in the group represented by the general formula (1) is preferably hydrogen, a methyl group, or an acetyl group. Examples of such compounds include 1,3-bis (hydroxymethyl) -benzene, 1,4-bis (hydroxymethyl) -benzene, 2,6-bis (hydroxymethyl) -phenol, and 2,6-bis. (Hydroxymethyl) -para-cresol, oxybis (3,4-dihydroxymethyl) benzene, 4,4′-methylenebis [2,6-di (hydroxymethyl)] phenol, 2,4,6-tris [bis (methoxy Methyl) amino] -1,3,5-triazine, Nippon Cytec Cymel (registered trademark), DML-PC (Honshu Chemical Industry Co., Ltd.), TML-BPA-MF (Honshu Chemical Industry Co., Ltd.), TML- BPAF-MF (manufactured by Honshu Chemical Industry Co., Ltd.), DML-OC (manufactured by Honshu Chemical Industry Co., Ltd.), Dimethymethyl p-CR (book) State Chemical Industry Co., Ltd.), DML-MBPC (Honshu Chemical Industry Co., Ltd.), DML-BPC (Honshu Chemical Industry Co., Ltd.), TML-BP (Honshu Chemical Industry Co., Ltd.), DML-PEP (Honshu Chemical Co., Ltd.) Industrial Co., Ltd.), DML-34X (Honshu Chemical Industry Co., Ltd.), DML-PSBP (Honshu Chemical Industry Co., Ltd.), DML-PCHP (Honshu Chemical Industry Co., Ltd.), DML-POP (Honshu Chemical Industry Co., Ltd.) Company-made), DML-PFP (made by Honshu Chemical Industry Co., Ltd.), DML-MBOC (made by Honshu Chemical Industry Co., Ltd.), 26DMPC (made by Asahi Organic Materials Industry Co., Ltd.), 46DMOC (made by Asahi Organic Materials Industry Co., Ltd.), DM-BIPC-F (Asahi Organic Material Industries Co., Ltd.), DM-BIOC-F (Asahi Organic Material Industries Co., Ltd.), TM-BIP-A (Asahi Organic Material Industries Co., Ltd.), Carac (Sanwa Chemical Co., Ltd.) and the like, and the other compounds shown in Scheme 1 in [Reference 1] satisfying the conditions of Compound X, that is, the following structural formulas (4) to (16) In addition to the 13 compounds represented by the following formulas and the 16 compounds represented by the following structural formulas (17) to (32), there are those exemplified, but the invention is not limited thereto.

The type of compound is not limited to one. Of the above compounds, 2,6-bis (hydroxymethyl) -para-cresol or 2,4,6-tris [2] is considered in consideration of easy availability, easy reaction, and desired effects. Bis (methoxymethyl) amino] -1,3,5-triazine is preferred.
[Reference 1] Macromolecules 1994, 27, 5154-5159.

  In this impregnation step, compound X is preferably used by impregnating a polymer film or polymer electrolyte membrane that has already been formed into a film. By impregnating the compound X in this form, the operation of this impregnation step is simplified and the design of the finally produced polymer electrolyte membrane is facilitated. When the compound X is impregnated, it may be used as it is if the compound X is in a liquid state, or may be diluted with an appropriate solvent. When compound X is a solid, it is preferably dissolved in an appropriate solvent. In either case, the reaction of Compound X to the polymer film or polymer electrolyte membrane can be controlled by diluting with an appropriate solvent and controlling the concentration of Compound X in the solution. As the solvent, a solvent that does not inhibit the reaction of Compound X to the polymer film or polymer electrolyte and does not deteriorate the polymer film or polymer electrolyte is preferable. In addition, since the polymer X (or polymer electrolyte membrane) is impregnated with the compound X, a solvent that can easily swell the polymer film or polymer electrolyte is preferable. Examples of such solvents include, but are not limited to, water, alcohols such as methanol, ethanol, and polar solvents such as acetone. Two or more kinds of solvents may be appropriately mixed and used.

In order to efficiently impregnate and bond the compound X into the polymer film,
(I) a step of coexisting with the compound X a catalyst that promotes the binding of the compound X and the polymer film or polymer electrolyte membrane during the impregnation step; and (II) after the impregnation step, the compound X and Preferably, the production method of the present invention includes a step of bringing a catalyst that promotes bonding with the polymer film or the polymer electrolyte membrane into contact with the polymer film. Moreover, it is preferable that the manufacturing method of this invention includes the process of heating the polymer film (or polymer electrolyte membrane) at the time of the said impregnation process and / or after an impregnation process. According to the above aspect, since the binding between the compound X and the polymer film (or polymer electrolyte membrane) is promoted, the methanol permeability is reduced, and the swelling with respect to a hydrogen-containing liquid such as methanol is suppressed, A polymer electrolyte membrane having durability against a hydrogen-containing liquid such as methanol can be more efficiently produced.

  The catalyst is not particularly limited as long as it is a substance that promotes the bond between the compound X and the polymer film (or polymer electrolyte membrane), but an acid is particularly preferable. Examples of the acid include sulfonic acids such as methanesulfonic acid and benzenesulfonic acid; organic acids such as carboxylic acids such as acetic acid and benzoic acid; or general inorganic acids. In the case where an acid is used during the introduction step, the acid used in the introduction step can be used as the catalyst. Therefore, it can be said that it is preferable to perform the impregnation step after the introduction step.

  Moreover, what is necessary is just to set suitably the conditions for advancing reaction appropriately for the heating conditions performed in order to accelerate | stimulate the coupling | bonding of the compound X and a polymer film (or polymer electrolyte membrane). In particular, the heating conditions can be set in consideration of the thermal stability of the polymer film (or polymer electrolyte membrane), the bonding speed between the compound X and the polymer film (or polymer electrolyte membrane), and the like.

  In the production method of the present invention, the amount of the compound X impregnated in the polymer film (or polymer electrolyte membrane) varies depending on the types of the compound X and the polymer film (or polymer electrolyte membrane). It is sufficient to set appropriate conditions as appropriate.

  The polymer film used in the present invention is a film used as a material for the polymer electrolyte membrane. The polymer film is not particularly limited as long as the compound X can be impregnated. However, it is preferable that the polymer film has preferable characteristics as a material for the polymer electrolyte membrane for fuel cells. The preferable characteristics include, for example, being stable with respect to temperature when used as a fuel cell and being chemically stable with respect to hydrogen or methanol as a fuel. Examples of the polymer film include a polyolefin film, a fluorine film, and an aromatic film.

  In order to realize excellent proton conductivity and high methanol barrier properties, it is more preferable to use a polymer film produced by combining different materials in the production method of the present invention. Specifically, a polymer film containing a polymer compound having an aromatic unit and a polymer compound having no aromatic unit is preferably used in the production method of the present invention. In polymer films, proton-conducting groups such as sulfonic acid groups are introduced into portions having aromatic units, but proton-conducting groups such as sulfonic acid groups are introduced into portions having no aromatic units. There is no. Therefore, the polymer electrolyte membrane obtained from the polymer film has a structure that hardly swells in water or an aqueous methanol solution despite the introduction of hydrophilic proton conductive groups such as sulfonic acid groups. A polymer electrolyte membrane having high methanol barrier properties can be obtained.

Here, the polymer compound having an aromatic unit used in the production method of the present invention may literally be a polymer compound having an aromatic unit conventionally known to those skilled in the art. For other specific configurations, There is no particular limitation. Examples of the polymer compound having an aromatic unit include polyaryl ether sulfone, polyether ether sulfone, polyether ketone, polyether ketone ketone, polysulfone, polyparaphenylene, polyphenylene sulfide, polyphenylene ether, polyphenylene sulfoxide, polyphenylene sulfide. Sulfone, polyphenylenesulfone, polybenzimidazole, polybenzoxazole, polybenzothiazole, polystyrene, syndiotactic polystyrene, polyethersulfone, styrene- (ethylene-butylene) styrene copolymer, styrene- (polyisobutylene) -styrene copolymer Union, poly 1,4-biphenylene ether ether sulfone, polyarylene ether sulfone, polyimide, polyether Imide, cyanate ester resin, polyether ether ketone, polyethylene-polystyrene graft copolymer, polyethylene-polystyrene block copolymer, polypropylene-polystyrene graft copolymer, (ethylene-glycidyl methacrylate) -polystyrene graft copolymer, Ethylene-ethyl acrylate) -polystyrene graft copolymer, polypropylene- (acrylonitrile-styrene) graft copolymer, polycarbonate-polystyrene graft copolymer, polycarbonate- (acrylonitrile-styrene) graft copolymer, vinyl acetate resin-polystyrene block Copolymer, acrylic resin-polystyrene block copolymer, Modiper series (manufactured by NOF Corporation, registered trademark), Epofriendcy (Manufactured by Daicel Chemical Co., Ltd.), and the like. In particular, chemical stability and thermal stability, ease of introduction of proton-conductive substituents, proton conductivity of the resulting proton-conductive polymer electrolyte, and methanol of the resulting proton-conductive polymer electrolyte membrane In consideration of blocking properties, the polymer compound (A) having an aromatic unit is preferably one polymer selected from the following (i) to (iii), or a mixture of these polymers. .
(I) at least one polymer selected from the group of polymers consisting of polystyrene, syndiotactic polystyrene, polyphenylene ether, modified polyphenylene ether, polysulfone, polyethersulfone, polyetheretherketone, and polyphenylene sulfide;
(Ii) a copolymer comprising the polymer described in (i) above;
(Iii) Derivatives of the polymers described in (i) and (ii) above.

  On the other hand, a polymer compound having no aromatic unit that can be used in the production method of the present invention (a polymer compound having no aromatic unit) literally means a compound having no aromatic unit in its structure. . Since whether or not an aromatic unit is contained in the polymer compound can be easily confirmed by a known method such as NMR, the “polymer compound having no aromatic unit” and the “aromatic unit” Those skilled in the art can easily understand “polymer compound having”. Examples of the polymer compound having no aromatic unit include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 4-methyl-1-pentene, and 5-methyl- Α-olefin homopolymers such as 1-heptene or polyolefin resins containing these copolymers, cyclic polyolefins such as norbornene resins, polyvinyl chloride; vinyl chloride-vinyl acetate copolymers; vinyl chloride-vinylidene chloride Copolymer; vinyl chloride resin including vinyl chloride-olefin copolymer; nylon 6; polyamide resin including nylon 66; and polytetrafluoroethylene; tetrafluoroethylene-perfluoroalkylvinyl ether copolymer; tetra Fluoroethylene-exafluoropropylene copolymer ; Tetrafluoroethylene - ethylene copolymer; polychlorotrifluoroethylene; polyvinylidene fluoride; and fluorine-based resins such as polyvinyl fluoride and the like.

  The polymer compound having no aromatic unit is compatible or dispersible with other polymer compound components, processability when producing a polymer film, handling property of the resulting polymer film, and high performance obtained therefrom. In consideration of methanol blocking property, chemical stability, thermal stability, etc. of the molecular electrolyte membrane, one polymer selected from a polymer compound having a repeating unit of the following general formula (3), or a mixture thereof It is particularly preferred that

-(CX ₁ X ₂ -CX ₃ X ₄ )-(3)
(Wherein X _{1 to 4} are any one selected from the group consisting of H, CH ₃ , Cl, F, OCOCH ₃ , CN, COOH, COOCH ₃ , and OC ₄ H ₉ , wherein X _{1 -4} may be the same or different from each other)
Furthermore, in view of industrial availability, mechanical properties and handling properties of the resulting polymer film, proton conductivity, methanol blocking property, chemical stability, etc. of the obtained polymer electrolyte membrane, the above aromatic unit It is preferable that the polymer compound not having polyethylene includes polyethylene and / or polypropylene. Various additives commonly used in the production of polymer films, such as compatibilizers for improving compatibility, antioxidants for preventing resin deterioration, and antistatics for improving handling in film processing Agents, lubricants, and the like can be appropriately used as long as they do not affect the processability and performance of the polymer electrolyte membrane. In particular, when a polymer resin film is produced by combining different materials, it is preferable to use a compatibilizing agent in order to increase the compatibility.

(1-2) Film formation process The film formation process in the manufacturing method of this invention is a process of manufacturing a polymer film. In the film forming step, a known method can be appropriately used as a method for manufacturing a polymer film. Examples of the leaving method include melt extrusion molding such as inflation method and T-die method, calendering method, casting method, cutting method, emulsion method, hot pressing method, and the like. Furthermore, in the production method of the present invention, in order to control the molecular orientation of the polymer film, the obtained polymer film is subjected to a treatment such as biaxial stretching or the degree of crystallinity is controlled. Heat treatment may be performed. It is also within the scope of the present invention to add various fillers in order to improve the mechanical strength of the polymer film or to combine a reinforcing agent such as a glass nonwoven fabric with the polymer film by pressing.

  In this step, various additives usually used in the production of polymer films can also be used.

  In view of productivity, mechanical properties of the polymer film obtained, ease of film thickness control, applicability to various resins, environmental load, etc. It is preferable to manufacture. Specifically, a method in which a polymer film material is put into an extruder in which a T-die is set, and film formation is performed while melt-kneading can be applied. Furthermore, it is possible to apply a method in which pellets and powders of a polymer compound not having an aromatic unit are preliminarily mixed at a predetermined blending ratio and formed into a film while being similarly melt-kneaded. At this time, if the extruder used is a twin screw extruder, a polymer film in which these components are melted and uniformly dispersed can be obtained. Further, the film may be formed using pellets melt-kneaded with a twin-screw extruder so as to have a predetermined blending ratio in advance, or a masterbatch pellet is used to obtain a predetermined blending ratio. Thus, the film may be formed while melt-kneading. Moreover, when there is no problem in the dispersibility of the components to be combined, the film may be formed with a single screw extruder in which a T die is set.

  Arbitrary thickness can be selected as thickness of the polymer film manufactured according to a use. For example, in consideration of reducing the internal resistance of the polymer electrolyte membrane obtained from the polymer film, the thinner the polymer film, the better. On the other hand, in consideration of methanol barrier properties and handling properties of the obtained polymer electrolyte membrane, it may be undesirable if the thickness of the polymer film is too thin. Considering these, the thickness of the polymer film is preferably 1.2 μm or more and 350 μm or less. If the thickness of the polymer film is within the above range, film formation is easy, and wrinkles are less likely to occur during processing when a proton conductive group is introduced or during drying. In addition, handling is improved such that damage is unlikely to occur. In addition, the proton conductivity of the obtained polymer electrolyte membrane can be expressed within a desired range.

(1-3) Introduction Step The introduction step in the production method of the present invention is a step for introducing a proton conductive group into the polymer film. In other words, the introducing step is a step of bringing the polymer film and the proton conductive group introducing agent into contact with each other. Alternatively, it can be said that this step is a step of causing the polymer film to exhibit a function as a so-called polymer electrolyte membrane. Such an introduction step may be performed before or after the impregnation step. Further, the introduction step may be performed simultaneously with the impregnation step. However, considering the ease of impregnation with compound X, it is preferable to introduce a proton conductive group into the polymer film in advance. Therefore, it can be said that the introduction step is preferably performed before the impregnation step.

  As the introduction step, a known method for introducing a proton conductive group can be used. In particular, the method of bringing a polymer film into contact with a proton conductive group introducing agent in the presence of an organic solvent provides a polymer electrolyte membrane that achieves both excellent proton conductivity and high methanol blocking property with a simple and high productivity. preferable.

  Here, any proton-conducting group can be used as long as it can dissociate protons in a water-containing state. For example, a sulfonic acid group, a phosphoric acid group, a carboxylic acid group, a phenolic hydroxyl group and the like can be exemplified, but not limited thereto. In view of easiness of introduction of proton conductive groups and proton conductivity of the resulting polymer electrolyte, sulfonic acid groups are preferred. The ion exchange capacity of the polymer electrolyte derived from the content of the proton conductive group is preferably 0.3 meq / g or more, more preferably 0.5 meq / g or more. When the ion exchange capacity is 0.3 meq / g or more, the polymer electrolyte membrane is likely to exhibit preferable proton conductivity.

  As the proton conductive group introducing agent used for introducing the proton conductive group, a sulfonating agent can be preferably used. By contacting the polymer film and the proton conductive group introducing agent (preferably sulfonating agent) in the presence of an organic solvent, the proton conductive group introducing agent (preferably sulfonating agent) is brought into direct contact with the polymer film. It becomes possible to introduce a desired amount of the sulfonic acid group while suppressing the deterioration.

  Examples of the sulfonating agent that can be used in the present invention include known sulfonating agents such as chlorosulfonic acid, fuming sulfuric acid, sulfur trioxide, sulfur trioxide-triethyl phosphate, concentrated sulfuric acid, and trimethylsilyl chlorosulfate. preferable. In consideration of industrial availability, ease of introduction of sulfonic acid groups, and characteristics of the obtained polymer electrolyte membrane, it is preferable to use chlorosulfonic acid alone or a mixture containing chlorosulfonic acid. That is, in the present invention, the sulfonating agent is preferably chlorosulfonic acid. This is because when the sulfonating agent is chlorosulfonic acid, a sulfonic acid group that is a proton conductive group is easily introduced, and a polymer electrolyte membrane having high proton conductivity can be easily obtained.

  The organic solvent that can be used in the above process does not degrade the sulfonating agent, does not inhibit the introduction of sulfonic acid groups into the aromatic unit, and degrades the thermoplastic polymer and antioxidant in the film. As long as it does not cause the problem, it can be used and is not particularly limited. By using the organic solvent in this way, the polymer film can easily swell and the sulfonating agent can be diffused into the film. Moreover, it can suppress that a sulfonating agent and a polymer film contact directly, and an excessive reaction arises and a film deteriorates.

  In the present invention, considering the ease of introduction of sulfonic acid groups and the characteristics of the polymer electrolyte membrane obtained, the organic solvent is particularly preferably a halogenated hydrocarbon. Examples of the halogenated hydrocarbon include dichloromethane, 1,2-dichloroethane, chloroform, 1-chloropropane, 1-chlorobutane, 2-chlorobutane, 1,4-dichlorobutane, 1-chloro-2-methylpropane, and 1-chloro. Examples include pentane, 1-chlorohexane, and chlorocyclohexane. In particular, the halogenated hydrocarbon is selected from the group consisting of dichloromethane, 1,2-dichloroethane, and 1-chlorobutane, taking into consideration industrial availability, ease of introduction of sulfonic acid groups, and characteristics of the obtained electrolyte membrane. It is preferable that the organic solvent contains at least one selected from the above. That is, in the present invention, the organic solvent preferably contains dichloromethane or 1-chlorobutane. When the organic solvent is dichloromethane or 1-chlorobutane, these are easily industrially available, and a proton conductive group can be easily introduced, and the proton conductivity and methanol blocking property of the obtained polymer electrolyte membrane can be compatible. .

  The amount of the sulfonating agent used is 0.1 to 100 times (weight ratio), more preferably 0.5 to 50 times (weight ratio) with respect to the polymer film. preferable. If the amount of the sulfonating agent used is within the above-mentioned preferable numerical range, the amount of sulfonic acid groups introduced is within a suitable range, and the properties such as proton conductivity of the obtained polymer electrolyte membrane can be sufficiently secured. In addition, the polymer film can be prevented from being chemically deteriorated, and the mechanical strength of the resulting polymer electrolyte membrane can be prevented from being lowered. For this reason, handling is easy. In addition, sulfonic acid groups can be introduced in a suitable range, and deterioration of practical characteristics of the polymer electrolyte membrane, such as being soluble in water or methanol aqueous solution, can be prevented while maintaining methanol blocking properties.

  In addition, the concentration of the sulfonating agent in the organic solvent may be appropriately set in consideration of the target introduction amount of sulfonic acid groups and reaction conditions (temperature, time, etc.). Specifically, it is preferably 0.05% by weight or more and 20% by weight or less, and more preferably 0.2% by weight or more and 10% by weight or less. If it is in the range of 0.05% by weight to 20% by weight, the sulfonating agent and the aromatic unit in the polymer film can easily come into contact with each other, a desired amount of sulfonic acid group can be introduced, and the introduction time is short. Time is enough. Further, the introduction of sulfonic acid groups becomes uniform, and the mechanical properties of the obtained polymer electrolyte membrane can be sufficiently secured.

The reaction temperature for bringing the polymer film into contact with the sulfonating agent is not particularly limited, but is preferably 0 ° C. or higher and 100 ° C. or lower, more preferably 10 ° C. or higher and 30 ° C. or lower. If reaction temperature is 0 degreeC or more, measures, such as cooling on an installation, are unnecessary and it can prevent taking time more than necessary for reaction. Moreover, if it is 100 degrees C or less, reaction can be adjusted appropriately, generation | occurrence | production of a side reaction can be prevented and the problem of reducing the characteristic of a film | membrane can be avoided. Furthermore, it can be said that the reaction temperature when the polymer film and the sulfonating agent are brought into contact with each other is preferably equal to or lower than the boiling point of the organic solvent to be used because it is not necessary to use a pressure resistant container.
The reaction time for bringing the polymer film into contact with the sulfonating agent is not particularly limited, but the lower limit thereof is preferably 0.5 hours or more, and more preferably 2 hours or more. On the other hand, the upper limit of the reaction time is preferably 100 hours or less. When the reaction time is 0.5 hour or longer, the contact between the sulfonating agent and the aromatic unit in the polymer film is sufficient, and a desired amount of sulfonic acid groups can be introduced. Moreover, if the reaction time is 100 hours or less, the characteristics of the polymer electrolyte membrane can be improved without impairing the productivity. Actually, in consideration of the reaction atmosphere of the sulfonating agent and organic solvent to be used, the target production amount, etc., a polymer electrolyte membrane having desired characteristics can be efficiently produced, and the reaction conditions are set. What is necessary is just to set suitably.

  In order to further improve the properties of the polymer electrolyte membrane produced by the production method of the present invention, it is possible to irradiate radiation such as electron beam, γ-ray, ion beam and the like. As a result, a crosslinked structure or the like can be introduced into the polymer electrolyte membrane, and the methanol barrier property may be further improved. Further, various surface treatments such as plasma treatment and corona treatment can improve properties such as improving the adhesion of the catalyst layer on the surface of the polymer electrolyte membrane.

<2. Use of Polymer Electrolyte Membrane According to the Present Invention>
The polymer electrolyte membrane according to the present invention can be used in various industries, and the use (use) is not particularly limited. For example, a membrane using the above polymer electrolyte membrane- An electrode assembly can be mentioned. Such a membrane-electrode assembly can be used, for example, in a fuel cell, particularly a fuel cell such as a solid polymer fuel cell, a direct liquid fuel cell, and a direct methanol fuel cell.

  That is, the present invention may include a fuel cell using the polymer electrolyte membrane.

  According to the membrane-electrode assembly and the fuel cell, since the polymer electrolyte membrane having both excellent proton conductivity and high methanol barrier property as described above is provided, it has high power generation characteristics and long-term durability.

  Next, an embodiment of a polymer electrolyte fuel cell using the polymer electrolyte membrane of the present invention will be described with reference to the drawings. In the present embodiment, a solid polymer fuel cell will be described as an example, but a direct liquid fuel cell and a direct methanol fuel cell can also be implemented in the same manner as a solid polymer fuel cell. .

  FIG. 1 is a diagram schematically showing a cross-sectional structure of a main part of a polymer electrolyte fuel cell using a polymer electrolyte membrane according to the present embodiment. As shown in the figure, a polymer electrolyte fuel cell 10 according to the present embodiment includes a polymer electrolyte membrane 1, catalyst layers 2 and 2, diffusion layers 3 and 3, and separators 4 and 4.

  The polymer electrolyte membrane 1 is located substantially at the center of the cell of the solid polymer fuel cell 10. The catalyst layer 2 is provided in contact with the polymer electrolyte membrane 1. The diffusion layer 3 is provided adjacent to the catalyst layer 2, and a separator 4 is disposed on the outer side thereof. The separator 4 is formed with a flow path 5 for feeding fuel gas or liquid (such as aqueous methanol solution) and an oxidant. In other words, these members are configured as cells of the polymer electrolyte fuel cell 10.

  Generally, a polymer electrolyte membrane 1 joined with a catalyst layer 2 or a polymer electrolyte membrane 1 joined with a catalyst layer 2 and a diffusion layer 3 is referred to as a membrane-electrode assembly (hereinafter referred to as “MEA”). It is used as a basic member of a polymer electrolyte fuel cell (direct liquid fuel cell, direct methanol fuel cell).

  Methods for producing MEA are conventionally studied polymer electrolyte membranes made of perfluorocarbon sulfonic acid and other hydrocarbon polymer electrolyte membranes (for example, sulfonated polyetheretherketone, sulfonated polyethersulfone, sulfone). A known method performed with a sulfonated polysulfone, a sulfonated polyimide, a sulfonated polyphenylene sulfide, or the like is applicable.

  An example of a specific method for producing MEA is shown below, but the present invention is not limited to this.

  The catalyst layer 2 is formed by dispersing a metal-supported catalyst in a polymer electrolyte solution or dispersion to prepare a dispersion for forming the catalyst layer. The dispersion solution is applied onto a release film such as polytetrafluoroethylene by spraying, and the solvent in the dispersion solution is dried and removed to form a predetermined catalyst layer 2 on the release film. The catalyst layer 2 formed on the release film is disposed on both surfaces of the polymer electrolyte membrane 1, and hot-pressed under predetermined heating and pressurizing conditions to join the polymer electrolyte membrane 1 and the catalyst layer 2 and release them. The MEA in which the catalyst layers 2 are formed on both surfaces of the polymer electrolyte membrane 1 can be produced by peeling the mold film.

  Also, a catalyst-carrying gas diffusion electrode in which the dispersion solution is coated on the diffusion layer 3 using a coater or the like, the solvent in the dispersion solution is dried and removed, and the catalyst layer 2 is formed on the diffusion layer 3 Are arranged on both sides of the polymer electrolyte membrane 1, and the catalyst layer 2 side of the catalyst-carrying gas diffusion electrode is placed on both sides of the polymer electrolyte membrane 1 by hot pressing under predetermined heating and pressurizing conditions. An MEA in which the catalyst layer 2 and the diffusion layer 3 are formed can be manufactured. In addition, you may use a commercially available gas diffusion electrode (made by USA E-TEK company etc.) for the said catalyst carrying | support gas diffusion electrode.

  Examples of the polymer electrolyte solution include an alcohol solution of a perfluorocarbon sulfonic acid polymer compound (such as Nafion (registered trademark) solution manufactured by Aldrich) or a sulfonated aromatic polymer compound (eg, sulfonated polyether ether ketone). , Sulfonated polyethersulfone, sulfonated polysulfone, sulfonated polyimide, sulfonated polyphenylene sulfide, and the like) can be used. As the metal-supported catalyst, conductive particles having a high specific surface area can be used as a carrier, and examples thereof include carbon materials such as activated carbon, carbon black, ketjen black, vulcan, carbon nanohorn, fullerene, and carbon nanotube.

  Any metal catalyst may be used as long as it promotes the fuel oxidation reaction and oxygen reduction reaction, and the fuel electrode and the oxidant electrode may be the same or different. For example, noble metals such as platinum and ruthenium or alloys thereof can be exemplified, and a promoter for promoting their catalytic activity or suppressing poisoning by reaction by-products may be added.

  The dispersion solution for forming the catalyst layer may be appropriately diluted with water or an organic solvent in order to adjust the viscosity so that it can be easily applied by spraying or coated by a coater. Moreover, you may mix fluorine-type compounds, such as tetrafluoroethylene, in order to provide water repellency to the catalyst layer 2 as needed.

  As the diffusion layer 3, a porous conductive material such as carbon cloth or carbon paper can be used. In order to promote the diffusibility of the fuel and the oxidant and the discharge of reaction by-products and unreacted substances, it is preferable to use those which are coated with tetrafluoroethylene or the like to impart water repellency. Further, an adhesive layer made of a polymer electrolyte as described above may be provided between the polymer electrolyte membrane 1 and the catalyst layer 2 as necessary.

  The conditions for hot pressing the polymer electrolyte membrane 1 and the catalyst layer 2 under heating and pressurizing conditions need to be appropriately set according to the type of polymer electrolyte contained in the polymer electrolyte membrane 1 and the catalyst layer 2 to be used. is there. The above-mentioned condition is that the polymer electrolyte contained in the polymer electrolyte membrane 1 or the catalyst layer 2 is generally below the thermal degradation or thermal decomposition temperature of the polymer electrolyte contained in the polymer electrolyte membrane 1 or the catalyst layer 2. It is preferable that the glass transition point and the softening point are higher than the glass transition point, and the temperature condition is higher than the glass transition point and the softening point of the polymer electrolyte contained in the polymer electrolyte membrane 1 and the catalyst layer 2.

  As the pressurizing condition, it is preferable that the pressure is in the range of about 0.1 MPa or more and 20 MPa or less because the polymer electrolyte membrane 1 and the catalyst layer 2 are in sufficient contact with each other and there is no deterioration in characteristics due to significant deformation of the material used. In particular, when the MEA is formed only from the polymer electrolyte membrane 1 and the catalyst layer 2, the diffusion layer 3 may be disposed outside the catalyst layer 2 and used only by contacting without being joined.

  The MEA obtained by the above method is inserted between a pair of separators 4 in which a flow path 5 for feeding fuel gas or liquid and an oxidant is formed, and the solid according to the present embodiment. A polymer fuel cell 10 is obtained.

  As the separator 4, a conductive material such as carbon graphite or stainless steel can be used. In particular, when a metal material such as stainless steel is used, it is preferable to perform a corrosion resistance treatment.

  For the polymer electrolyte fuel cell 10 described above, a gas containing hydrogen as a main component or a gas or liquid containing methanol as a main component as a fuel gas or liquid, and a gas containing oxygen (oxygen or oxygen) as an oxidant. The solid polymer fuel cell generates electric power by supplying air) to the catalyst layer 2 via the diffusion layer 3 from the respective separate flow paths 5. At this time, for example, when a hydrogen-containing liquid is used as the fuel, a direct liquid fuel cell is obtained, and when methanol is used, a direct methanol fuel cell is obtained. That is, it can be said that the above-described embodiment exemplified for the polymer electrolyte fuel cell 10 can be applied to a direct liquid fuel cell and a direct methanol fuel cell as they are.

  In addition, the polymer electrolyte fuel cell 10 according to the present embodiment can be used alone or in a stacked manner to form a stack, or a fuel cell system incorporating them.

  Next, an embodiment of a direct methanol fuel cell using the polymer electrolyte membrane of the present invention will be described with reference to the drawings.

  FIG. 2 is a diagram schematically showing a cross-sectional structure of a main part of a direct methanol fuel cell made of the polymer electrolyte membrane according to the present embodiment. As shown in the figure, a direct methanol fuel cell 20 according to the present embodiment includes an MEA 16, a fuel tank 17, and a support 19. The fuel tank 17 includes a fuel (methanol or methanol aqueous solution) filling unit (supply unit) 18, and an oxidant channel 15 is formed in the support 19.

  The required number of MEAs 16 obtained by the above-described method is arranged in a plane on both sides of the fuel tank 17 having the fuel filling portion 18. Further, a support body 19 in which an oxidant channel 15 is formed is disposed on the outside thereof. That is, a cell or stack of the direct methanol fuel cell 20 is configured by being sandwiched between the two supports 19 and 19.

  In addition to the examples described above, the polymer electrolyte membrane according to the present invention is disclosed in JP 2001-313046, JP 2001-313047, JP 2001-93551, and JP 2001-93558. JP-A-2001-93561, JP-A-2001-102069, JP-A-2001-102070, JP-A-2001-283888, JP-A-2000-268835, JP-A-2000-268836, It can be used as an electrolyte membrane of a polymer electrolyte fuel cell or a direct methanol fuel cell, which is publicly known in Japanese Laid-Open Patent Publication No. 2001-283893. Based on these known documents, those skilled in the art can easily construct a polymer electrolyte fuel cell or a direct methanol fuel cell using the polymer electrolyte membrane of the present invention.

  Hereinafter, examples will be shown, and the embodiment of the present invention will be described in more detail. Of course, the present invention is not limited to the following examples, and it goes without saying that various aspects are possible in detail. Further, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims, and the present invention is also applied to the embodiments obtained by appropriately combining the disclosed technical means. It is included in the technical scope of the invention.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited at all by these Examples, In the range which does not change the summary, it can change suitably.

Example 1
<Preparation of polymer electrolyte membrane>
Polyphenylene sulfide (Dainippon Ink Chemical Co., Ltd., LD10p11) is used as a polymer compound having an aromatic unit, and high-density polyethylene (HI-ZEX 3300F, manufactured by Mitsui Chemicals, Inc.) is used as a polymer compound having no aromatic unit. did.

  30 parts by weight of polyphenylene sulfide pellets and 70 parts by weight of high density polyethylene pellets were dry blended. The dry blended pellet mixture was melt-extruded by a twin screw extruder with a T die set under the conditions of a screw temperature of 290 ° C. and a T die temperature of 290 ° C. to obtain a polymer film (high in the polymer film). 70% by weight of density polyethylene).

  In a glass container, 905 g of dichloromethane and 9.0 g of chlorosulfonic acid were weighed to prepare a 1% by weight chlorosulfonic acid solution. 2.1 g of the polymer film was weighed, immersed in the chlorosulfonic acid solution, and allowed to stand at 25 ° C. for 20 hours (the amount of chlorosulfonic acid added was 4.3 times the weight of the polymer film). . Thereafter, the polymer film was recovered and washed with ion exchange water until neutral.

  The polymer film after washing was dried in a constant temperature and humidity chamber adjusted to 23 ° C. for 30 minutes under humidity control of relative humidity 98%, 80%, 60% and 50%, A polymer electrolyte membrane into which a sulfonic acid group was introduced as a proton conductive group was obtained.

  2,6-bis (hydroxymethyl) -para-cresol was dissolved in methanol at 10% by weight. The polymer electrolyte membrane obtained previously was immersed in this solution at 60 ° C. After 24 hours, it was taken out from the immersion and the solution on the surface of the polymer electrolyte membrane was wiped off. This polymer electrolyte membrane was treated in a vacuum dryer at 80 ° C. for 3 hours.

<Measurement method of ion exchange capacity>
A polymer electrolyte membrane (about 10 mm × 40 mm) was immersed in 20 mL of a saturated aqueous sodium chloride solution at 25 ° C., and subjected to an ion exchange reaction in a water bath at 60 ° C. for 3 hours. Thereafter, it was cooled to 25 ° C., and then the polymer electrolyte membrane was thoroughly washed with ion-exchanged water, and a saturated aqueous sodium chloride solution and washing water were all collected. To this recovered solution, a phenolphthalein solution was added as an indicator, and neutralization titration was performed with a 0.01N sodium hydroxide aqueous solution to calculate the ion exchange capacity. The results are shown in Table 1.

<Measurement method of proton conductivity>
A polymer electrolyte membrane (about 10 mm × 40 mm) stored in ion-exchanged water was taken out, and water on the surface of the polymer electrolyte membrane was wiped off with a filter paper. A polymer electrolyte membrane was placed in a dipolar non-sealed polytetrafluoroethylene cell, and a platinum electrode was placed on the membrane surface (on the same side) so that the distance between the electrodes was 30 mm. The membrane resistance at 23 ° C. was measured by an alternating current impedance method (frequency: 42 Hz to 5 MHz, applied voltage: 0.2 V, Hioki LCR meter 3531Z HITESTER), and proton conductivity was calculated. The results are shown in Table 1.

<Measurement method of methanol barrier properties>
In an environment at 25 ° C., ion exchange water and a 64% by weight aqueous methanol solution were isolated with a polymer electrolyte membrane using a membrane permeation experiment apparatus (KH-5PS) manufactured by Beadrex. A solution containing methanol permeated to the ion exchange water side after a predetermined time (2 hours) was collected, and the amount of methanol permeated with a gas chromatograph (Gas Chromatography GC-201 manufactured by Shimadzu Corporation) was quantified. From this quantitative result, the methanol permeation rate was determined, and the methanol permeation coefficient was calculated. The methanol permeability coefficient was calculated according to the following formula 1. The results are shown in Table 1.
[Formula 1]
Methanol permeability coefficient (μmol / (cm ・ day))
= Methanol permeation amount (μmol) × film thickness (cm) / (membrane area (cm ² ) × permeation time (days))
<Swelling evaluation method>
The electrolyte membrane obtained by the above method was immersed in a 64% by weight aqueous methanol solution and allowed to stand in an oven at 60 ° C. After 1000 hours, the electrolyte membrane was collected and visually compared with the state before immersion. When there was swelling, the area was measured and the ratio was calculated. The results are shown in Table 2.

<Method for evaluating methanol durability>
In a 100 cc pressure vessel, the electrolyte membrane obtained by the above method was cut to a size of about 1 cm 2 and put together with about 100 cc of a 64% by weight methanol aqueous solution. The lid of the pressure vessel was firmly attached and stored in a 100 ° C. ventilated oven for 120 hours. Thereafter, the pressure vessel was taken out of the oven and cooled to room temperature, and then the electrolyte membrane was taken out of the contents and ranked as follows by visual inspection and handling with tweezers. The results are shown in Table 2.

  A: There is no large swelling, and the shape is firmly maintained even if it is picked up by tweezers and lifted.

  B: Although there is no big swelling, self-supporting property is falling, and when it pinches with tweezers, it is torn or destroyed.

  C: Compared with before the test, the area is greatly swelled twice or more.

(Example 2)
<Preparation of polymer electrolyte membrane>
Implemented except that 2,4,6-tris [bis (methoxymethyl) amino] -1,3,5-triazine was used instead of 2,6-bis (hydroxymethyl) -para-cresol in Example 1. A sample was prepared in the same manner as in Example 1.

  The evaluation method was also the same as in Example 1. The results are shown in Table 2.

  Further, a TEM image (transmission electron microscope image) of this polymer electrolyte membrane is shown in FIG. 3 (a), and 2,4,6-tris [bis (methoxymethyl) amino] -1,3,5-triazine FIG. 3B shows an image obtained by mapping derived nitrogen with EDX (energy dispersive X-ray fluorescence spectrometer manufactured by Shimadzu Corporation).

(Example 3)
<Preparation of polymer electrolyte membrane>
Polyethylene-polystyrene graft copolymer (manufactured by NOF Corporation, Modiper (registered trademark) A1100) as a polymer having an aromatic unit, and high-density polyethylene (Mitsui Chemicals, Inc.) as a polymer compound having no aromatic unit. Manufactured by HI-ZEX 3300F).

  35 parts by weight of polyethylene-polystyrene graft copolymer pellets and 65 parts by weight of high density polyethylene pellets were dry blended. The dry blended pellet mixture was melt-extruded by a twin screw extruder with a T die set under the conditions of a screw temperature of 265 ° C. and a T die temperature of 265 ° C. to obtain a polymer film. Containing 65% by weight of density polyethylene).

  In a glass container, 149 g of 1-chlorobutane and 0.75 g of chlorosulfonic acid were weighed to prepare a 0.5 wt% chlorosulfonic acid solution. 0.35 g of the polymer film was weighed, immersed in the chlorosulfonic acid solution, and allowed to stand at 25 ° C. for 20 hours (the amount of chlorosulfonic acid added was 2.1 times the weight of the polymer film). . Thereafter, the polymer film was recovered and washed with ion exchange water until neutral.

  The polymer film after washing was dried in a constant temperature and humidity chamber adjusted to 23 ° C. for 30 minutes under humidity control of relative humidity 98%, 80%, 60% and 50%, A polymer electrolyte membrane was obtained.

  Next, in the same manner as in Example 1, a sample was prepared using 2,6-bis (hydroxymethyl) -para-cresol.

  The evaluation method was also the same as in Example 1. The results are shown in Tables 1 and 2.

Example 4
<Preparation of polymer electrolyte membrane>
Polyphenylene sulfide (Dainippon Ink Chemical Co., Ltd., LD10p11) is used as a polymer compound having an aromatic unit, and high-density polyethylene (HI-ZEX 3300F, manufactured by Mitsui Chemicals, Inc.) is used as a polymer compound having no aromatic unit. did.

  50 parts by weight of polyphenylene sulfide pellets and 50 parts by weight of high density polyethylene pellets were dry blended. The dry blended pellet mixture was melt-extruded by a twin screw extruder with a T die set under the conditions of a screw temperature of 290 ° C. and a T die temperature of 290 ° C. to obtain a polymer film (high in the polymer film). 50% by weight density polyethylene).

  In a glass container, 1295.0 g of dichloromethane and 9.7 g of chlorosulfonic acid were weighed to prepare a 0.7 wt% chlorosulfonic acid solution. 3.0 g of the polymer film was weighed, immersed in the chlorosulfonic acid solution, and allowed to stand at 25 ° C. for 20 hours (the amount of chlorosulfonic acid added was 3.2 times the weight of the polymer film). . Thereafter, the polymer film was recovered and washed with ion exchange water until neutral.

  The polymer film after washing was dried in a constant temperature and humidity chamber adjusted to 23 ° C. for 30 minutes under humidity control of relative humidity 98%, 80%, 60% and 50%, A polymer electrolyte membrane into which a sulfonic acid group was introduced as a proton conductive group was obtained.

  2,6-bis (hydroxymethyl) -para-cresol was dissolved in methanol at 50% by weight. The polymer electrolyte membrane obtained previously was immersed in this solution at 60 ° C. After 24 hours, it was taken out from the immersion and the solution on the surface of the polymer electrolyte membrane was wiped off. This polymer electrolyte membrane was treated in a vacuum dryer at 100 ° C. for 3 hours.

  The evaluation method was also the same as in Example 1. The results are shown in Tables 1 and 2.

(Example 5)
<Preparation of polymer electrolyte membrane>
Polyphenylene sulfide (Dainippon Ink Chemical Co., Ltd., LD10p11) is used as a polymer compound having an aromatic unit, and high-density polyethylene (HI-ZEX 3300F, manufactured by Mitsui Chemicals, Inc.) is used as a polymer compound having no aromatic unit. did.

  65 parts by weight of polyphenylene sulfide pellets and 35 parts by weight of high density polyethylene pellets were dry blended. The dry blended pellet mixture was melt-extruded by a twin screw extruder with a T die set under the conditions of a screw temperature of 290 ° C. and a T die temperature of 290 ° C. to obtain a polymer film (high in the polymer film). Containing 35% by weight of density polyethylene).

  In a glass container, 911 g of dichloromethane and 6.8 g of chlorosulfonic acid were weighed to prepare a 0.74% by weight chlorosulfonic acid solution. 2.1 g of the polymer film was weighed, immersed in the chlorosulfonic acid solution, and allowed to stand at 25 ° C. for 20 hours (the amount of chlorosulfonic acid added was 3.2 times the weight of the polymer film). . Thereafter, the polymer film was recovered and washed with ion exchange water until neutral.

  The polymer film after washing was dried in a constant temperature and humidity chamber adjusted to 23 ° C. for 30 minutes under humidity control of relative humidity 98%, 80%, 60% and 50%, A polymer electrolyte membrane into which a sulfonic acid group was introduced as a proton conductive group was obtained.

  DML-PC (Honshu Chemical Industry Co., Ltd.) was dissolved in methanol by 30% by weight. The polymer electrolyte membrane obtained previously was immersed in this solution at 60 ° C. After 24 hours, it was taken out from the immersion and the solution on the surface of the polymer electrolyte membrane was wiped off. This polymer electrolyte membrane was treated in a vacuum dryer at 120 ° C. for 3 hours.

  The evaluation method was also the same as in Example 1. The results are shown in Tables 1 and 2.

(Comparative Example 1)
<Preparation of polymer film>
As a polymer compound having an aromatic unit, polyphenylene sulfide (Dainippon Ink Industries, Ltd., DIC-PPS LD10p11) was used.

  The polyphenylene sulfide pellets were melt-extruded with a twin screw extruder in which a T die was set in a twin screw extruder under the conditions of a screw temperature of 290 ° C. and a T die temperature of 290 ° C. to obtain a polymer film.

<Preparation of polymer electrolyte membrane>
The polymer film obtained by the above method was used. Except for weighing 10.9 g of 1-chlorobutane and 1.1 g of chlorosulfonic acid to prepare a 1.5 wt% chlorosulfonic acid solution and changing the polymer film to 0.16 g, the same procedure as in Example 1 was performed. A polymer electrolyte membrane was obtained (the amount of chlorosulfonic acid added was 6.9 times that of the polymer film). The results are shown in Tables 1 and 2.

(Comparative Example 2)
Nafion (registered trademark) 115 manufactured by DuPont was used as the polymer electrolyte membrane. The results are shown in Tables 1 and 2.

(Comparative Example 3)
The polymer electrolyte membrane obtained in Example 1 was used as it was without being treated with 2,6-bis (hydroxymethyl) -para-cresol. The results are shown in Tables 1 and 2.

  From the comparison between Examples 1, 3, 4 and Comparative Example 2 in Table 1, the polymer electrolyte membrane obtained by the production method of the present invention is a polymer electrolyte membrane for a polymer electrolyte fuel cell. 2 has a proton conductivity of the same order as 2, which indicates that it is useful as a polymer electrolyte membrane for solid polymer fuel cells, direct liquid fuel cells, and direct methanol fuel cells.

  From the comparison between Examples 1 to 4 and Comparative Examples 1 to 3 in Tables 1 and 2, the polymer electrolyte membrane obtained by the production method of the present invention has a small methanol permeability coefficient and little swelling with respect to the methanol aqueous solution. Furthermore, it was revealed that it has durability against methanol, and it was shown to be useful as a polymer electrolyte membrane for a direct liquid fuel cell such as a direct methanol fuel cell.

  From the comparison between Example 5 in Tables 1 and 2 and Comparative Examples 1 to 3, the polymer electrolyte membrane obtained by the production method of the present invention has a proton conductivity that greatly exceeds the proton conductivity of the comparative example. As a polymer electrolyte membrane for direct liquid fuel cells such as direct methanol fuel cells, it has been revealed that it has a relatively small methanol permeability coefficient, has little swelling with respect to an aqueous methanol solution, and also has durability against methanol. It has been shown to be useful.

  FIG. 3 shows that nitrogen is unevenly distributed in the electrolyte component (polyphenylene sulfide) dispersed in the polymer electrolyte membrane. This shows that 2,4,6-tris [bis (methoxymethyl) amino] -1,3,5-triazine is unevenly distributed in the electrolyte component.

  The polymer electrolyte membrane according to the present invention has various industrial applicability including fuel cells such as solid polymer fuel cells, direct liquid fuel cells, and direct methanol fuel cells.

FIG. 1 is a diagram schematically showing a cross-sectional structure of a main part of a polymer electrolyte fuel cell using a polymer electrolyte membrane according to the present embodiment. FIG. 2 is a diagram schematically showing a cross-sectional structure of a main part of a direct methanol fuel cell made of the polymer electrolyte membrane according to the present embodiment. (A) is a TEM image of the electrolyte membrane in Example 2, and (b) is nitrogen derived from 2,4,6-tris [bis (methoxymethyl) amino] -1,3,5-triazine as EDX. This is a mapped image.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polymer electrolyte membrane 2 Catalyst layer 3 Diffusion layer 4 Separator 5 Channel 10 Solid polymer fuel cell 15 Oxidant channel 16 Membrane-electrode assembly (MEA)
17 Fuel Tank 18 Fuel Filling Portion 19 Support 20 Direct Methanol Fuel Cell

Claims (20)

In the method for producing a polymer electrolyte membrane including an introducing step of introducing a proton conductive group into the polymer film,
After the introduction step, a polymer electrolyte membrane in which a proton conductive group is introduced into the polymer film is impregnated with at least one compound X containing two or more groups represented by the following general formula (1) impregnation step of, and, viewed including the step of heating the polymer electrolyte membrane after the impregnation step at and / or impregnation step,
The polymer film is
(A) a polymer compound having an aromatic unit, and
(B) A method for producing a polymer electrolyte membrane , which is a polymer film containing a polymer compound having no aromatic unit :
-CH ₂ OR ··· (1)
(In the formula, R represents hydrogen, an alkyl group or an acyl group, and R contained in one kind of compound may be the same or different.)   The method for producing a polymer electrolyte membrane according to claim 1, wherein at least one of the compounds X is an aromatic compound derivative or a melamine derivative.   The method for producing a polymer electrolyte membrane according to claim 1, wherein at least one of the compounds X is 2,6-bis (hydroxymethyl) -para-cresol. The method for producing a polymer electrolyte membrane according to claim 1, wherein at least one of the compounds X is a compound represented by the general formula (2):

(Wherein R _{1 to} R ₆ each represent hydrogen or a methyl group). (A) above polymer compound having an aromatic unit, according to claim 1, characterized in that a mixture of one polymer or those polymers, which are selected from the following (i) ~ (iii) Production method of polymer electrolyte membrane:
(I) at least one polymer selected from the group of polymers consisting of polystyrene, syndiotactic polystyrene, polyphenylene ether, modified polyphenylene ether, polysulfone, polyethersulfone, polyetheretherketone, and polyphenylene sulfide;
(Ii) a copolymer comprising the polymer described in (i) above;
(Iii) Derivatives of the polymers described in (i) and (ii) above. The (B) polymer having no aromatic units, a request, which is a repeating unit one polymer selected from a polymer compound having, or mixtures thereof, of the following general formula (3) Item 6. The method for producing a polymer electrolyte membrane according to any one of Items 1 to 5 :
-(CX ₁ X ₂ -CX ₃ X ₄ )-(3)
_(Wherein, X _{1 to 4} is, H, based on any one _{of CH 3, Cl, F, OCOCH} 3, CN, COOH, are selected from the group consisting of COOCH _3, and _OC 4 _{H 9, X 1~ 4} are independent of each other and may be the same or different. The polymer compound having no aromatic unit (B) is one polymer selected from the group consisting of polyethylene, polypropylene, polymethylpentene, and derivatives thereof, or a mixture thereof. The method for producing a polymer electrolyte membrane according to any one of claims 1 to 5 . The method for producing a polymer electrolyte membrane according to any one of claims 1 to 7 , wherein the proton conductive group contains a sulfonic acid group. The method for producing a polymer electrolyte membrane according to any one of claims 1 to 8 , comprising the following steps (I) and / or (II):
(I) a step of allowing a catalyst to coexist with the compound X during the impregnation step;
(II) A step of bringing the catalyst into contact with a polymer film or a polymer electrolyte membrane formed by introducing a proton conductive group into the polymer film after the impregnation step. 10. The impregnation step is a step of immersing the polymer electrolyte membrane in a solution obtained by dissolving the compound X in water, alcohol, a polar solvent, or a mixed solvent of two or more of these. The manufacturing method of the polymer electrolyte membrane of any one of these . It is manufactured by the method for manufacturing a polymer electrolyte membrane according to any one of claims 1 to 10 ,
(A) a polymer compound having an aromatic unit, and
(B) At least one type including two or more groups represented by the following general formula (1) in a polymer electrolyte membrane in which a proton conductive group is introduced into a polymer film containing a polymer compound having no aromatic unit A polymer electrolyte membrane in which the above compound X is bonded:
-CH ₂ OR ··· (1)
(In the formula, R represents hydrogen, an alkyl group or an acyl group, and R contained in one kind of compound may be the same or different.) The polymer electrolyte membrane according to claim 11, wherein at least one of the compounds X is an aromatic compound derivative or a melamine derivative . 11. The polymer electrolyte membrane according to claim 10, wherein at least one of the compounds X is 2,6-bis (hydroxymethyl) -para-cresol . 14. The polymer electrolyte membrane according to claim 11, wherein at least one of the compounds X is a compound represented by the general formula (2):

(Wherein R _{1 to} R ₆ each represent hydrogen or a methyl group) . 15. The polymer compound having an aromatic unit (A) is one polymer selected from the following (i) to (iii), or a mixture of these polymers: The polymer electrolyte membrane according to any one of the above:
(I) at least one polymer selected from the group of polymers consisting of polystyrene, syndiotactic polystyrene, polyphenylene ether, modified polyphenylene ether, polysulfone, polyethersulfone, polyetheretherketone, and polyphenylene sulfide;
(Ii) a copolymer comprising the polymer described in (i) above;
(Iii) Derivatives of the polymers described in (i) and (ii) above . (B) The polymer compound having no aromatic unit is one polymer selected from polymer compounds having a repeating unit represented by the following general formula (3), or a mixture thereof: Item 15. The polymer electrolyte membrane according to any one of Items 11 to 15:
-(CX ₁ X ₂ -CX ₃ X ₄ )-(3)
_(Wherein, X _{1 to 4} is, H, based on any one _{of CH 3, Cl, F, OCOCH} 3, CN, COOH, are selected from the group consisting of COOCH _3, and _OC 4 _{H 9, X 1~ 4} are independent of each other and may be the same or different.) The polymer compound having no aromatic unit (B) is one polymer selected from the group consisting of polyethylene, polypropylene, polymethylpentene, and derivatives thereof, or a mixture thereof. The polymer electrolyte membrane according to any one of claims 11 to 15 . The polymer electrolyte membrane according to any one of claims 11 to 17, wherein the proton conductive group contains a sulfonic acid group . A membrane-electrode assembly comprising the polymer electrolyte membrane according to any one of claims 11 to 18 . A fuel cell comprising the polymer electrolyte membrane according to any one of claims 11 to 18 .

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