JP2006049003A - Solid polymer electrolyte, its manufacturing method, and solid polymer fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid polymer electrolyte that is inexpensive and excellent in oxidation resistance and durability. <P>SOLUTION: This solid polymer electrolyte contains a copolymer of one or more kinds of monomer selected from α-methyl styrene phosphonic acid, styrene phosphonic acid, α-methyl styrene alkyl phosphonic acid, and styrene alkyl phosphonic acid, and (meta) acrylic ester expressed by the general formula (A) (in the formula, R<SB>1</SB>is H or CH<SB>3</SB>, R<SB>2</SB>is H, CH<SB>3</SB>, or CH<SB>2</SB>Cl, and n is an integer of 1 to 10). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a solid polymer electrolyte, a production method thereof, and a solid polymer fuel cell.

  A solid polymer electrolyte is a solid polymer material having an electrolyte group such as a sulfonic acid group or a phosphonic acid group in a polymer chain, and is firmly bonded to a specific ion or selectively cation or anion. Since it has a permeating property, it is formed into particles, fibers, or films and used in various electrochemical devices.

  For example, in a polymer electrolyte fuel cell, a pair of electrodes are provided on both surfaces of an electrolyte membrane, a fuel gas containing hydrogen such as a reformed gas is supplied to one electrode (fuel electrode), and an oxygen containing oxygen such as air is oxidized. This is a battery in which the agent gas is supplied to the other electrode (air electrode), and the free energy change generated when the fuel is oxidized is directly taken out as electric energy. In a polymer electrolyte fuel cell, a polymer electrolyte membrane having proton conductivity is used as an electrolyte membrane.

  In addition, for example, an SPE (Solid Polymer Electrolyte) (electrolyte polymer) device is an apparatus for producing hydrogen and oxygen by electrolyzing water. As an electrolyte, instead of a conventional alkaline aqueous solution, a proton is used. A solid polymer electrolyte membrane having conductivity is used.

  As solid polymer electrolytes used in such various electrochemical devices, perfluoro-based electrolytes typified by Nafion (registered trademark, manufactured by DuPont) and various hydrocarbon-based electrolytes are known. In electrochemical devices used under severe conditions such as fuel cells and SPE electrolyzers, it is common to use a perfluoro-based electrolyte that has very high chemical stability and excellent oxidation resistance.

  This is because, in the case of fuel cells and SPE electrolyzers, peroxide is generated in the catalyst layer formed at the interface between the solid polymer electrolyte membrane and the electrode, and the generated peroxide is radicalized while diffusing in the electrolyte membrane. It is to do. Hydrocarbon electrolytes generally have low durability against peroxide radicals and are prone to degradation reactions due to peroxide radicals (oxidation reactions due to peroxide radicals), so they are used as electrolyte membranes for fuel cells and SPE electrolyzers. I can't do it.

  However, perfluoro-based electrolytes are very expensive because they are difficult to manufacture. In order to reduce the size, weight, and efficiency of electrochemical devices, it is effective to reduce the thickness of the electrolyte membrane and increase the operating temperature. For this purpose, the electrolyte membrane has strength and creep resistance. It is necessary to have excellent properties. However, since conventional perfluoro-based electrolytes are non-crosslinked, their strength and creep resistance are insufficient.

  In order to solve this problem, various proposals have been conventionally made. For example, a solid polymer electrolyte in which a functional group containing phosphorus such as a phosphonic acid group is introduced into a polymer compound having a hydrocarbon moiety has been proposed (see Patent Document 1).

  Further, a solid polymer electrolyte obtained by mixing a polymer compound having an electrolyte group and a hydrocarbon part and a compound containing phosphorus (for example, a polymer compound containing a phosphonic acid group) has been proposed ( Patent Document 2).

  A polymer electrolyte into which a functional group containing phosphorus is introduced has a hydrocarbon polymer compound as a main component, and is inexpensive. In addition, a polymer electrolyte into which a functional group containing phosphorus is introduced exhibits good oxidation resistance in an oxidation resistance test using a Fenton reagent, and durability in an environment where peroxide radicals are present can be expected.

However, in the proposals of Patent Document 1 and Patent Document 2, the process for introducing the functional group containing phosphorus into the polymer electrolyte is complicated, and it is necessary to further reduce the manufacturing cost. In addition, the proton conductivity of the electrolyte can be improved by increasing the amount of proton dissociation groups introduced into the electrolyte membrane, but these proposals require a complicated process for introducing proton dissociation groups.
JP 2000-11755 A JP 2000-11756 A

The present invention has been made in view of such a background art, and is to provide a solid polymer electrolyte that is inexpensive and excellent in oxidation resistance and durability.
Moreover, this invention is providing the manufacturing method of the solid polymer electrolyte which can manufacture said solid polymer electrolyte simply.
Another object of the present invention is to provide a solid polymer fuel cell excellent in durability using the above-mentioned solid polymer electrolyte.

  That is, the first invention of the present invention includes one or more monomers selected from α-methylstyrenephosphonic acid, styrenephosphonic acid, α-methylstyrenealkylphosphonic acid and styrenealkylphosphonic acid, and the following general formula (A A solid polymer electrolyte comprising a copolymer of (meth) acrylic acid ester represented by

(In the formula, R ₁ is H or CH ₃ , R ₂ is H, CH ₃ or CH ₂ Cl, and n is an integer of 1 to 10.)

  Further, the present invention is the production method of the first invention, wherein one or more monomers selected from α-methylstyrenephosphonic acid, styrenephosphonic acid, α-methylstyrenealkylphosphonic acid and styrenealkylphosphonic acid, A method for producing a solid polymer electrolyte comprising a step of copolymerizing a (meth) acrylic acid ester represented by the following general formula (A) to obtain a copolymer.

(In the formula, R ₁ is H or CH ₃ , R ₂ is H, CH ₃ or CH ₂ Cl, and n is an integer of 1 to 10.)

According to a second aspect of the present invention, there is provided one or two monomers selected from α-methylstyrene represented by the following structural formula (B ₁ ) and α-methylstyrene represented by the structural formula (C ₁ ): And a (meth) acrylic acid ester copolymer represented by the following general formula (A).

(In the formula, R ₁ is H or CH ₃ , R ₂ is H, CH ₃ or CH ₂ Cl, and n is an integer of 1 to 10.)

  Further, the present invention is the production method of the second invention, wherein one kind selected from α-methylstyrene represented by the following structural formula (B) and α-methylstyrene represented by the structural formula (C): Two types of monomers and a (meth) acrylic acid ester represented by the following general formula (A) are copolymerized and then hydrolyzed or oxidized to form a (N, N-diethylamino) phosphinyl group as a proton dissociation group. A method for producing a solid polymer electrolyte, comprising a step of obtaining a coalescence.

(In the formula, R ₁ is H or CH ₃ , R ₂ is H, CH ₃ or CH ₂ Cl, and n is an integer of 1 to 10.)

The third invention of the present invention is one or two kinds of monomer units selected from α-methylstyrene represented by the following structural formula (B ₁ ) and α-methylstyrene represented by the structural formula (C ₁ ). It is a solid polymer electrolyte characterized by including the polymer or copolymer which consists of these.

  Further, the present invention is the production method of the third invention, wherein one of monomers selected from α-methylstyrene represented by the following structural formula (B) and α-methylstyrene represented by the structural formula (C): A process comprising obtaining a polymer or copolymer having a (N, N-diethylamino) phosphinyl group as a proton dissociation group after anionic living polymerization of one or two types, followed by hydrolysis or oxidation; This is a method for producing a molecular electrolyte.

  A fourth invention of the present invention is a solid polymer fuel cell characterized by using the above-mentioned solid polymer electrolyte.

According to the present invention, by using a solid polymer electrolyte characterized in that it comprises a copolymer of α-methylstyrenephosphonic acid or styrenephosphonic acid and a (meth) acrylic acid ester containing a phosphate group, It is possible to provide an electrolyte membrane for a polymer electrolyte fuel cell that is inexpensive and excellent in oxidation resistance and durability.
Moreover, this invention can provide the manufacturing method of the solid polymer electrolyte which can obtain said electrolyte simply.

In addition, the present invention provides an anion living polymerization of α-methylstyrene having a (N, N-diethylamino) phosphinyl group substituted at the p-position represented by the structural formulas (B) and (C), followed by hydrolysis or oxidation. , A polymer having a (N, N-diethylamino) phosphinyl group as a proton dissociation group can be used.
In addition, the present invention can provide a highly durable fuel cell using the above electrolyte.

Hereinafter, embodiments of the present invention will be described in detail.
The first solid polymer electrolyte according to the present invention comprises one or more monomers selected from α-methylstyrenephosphonic acid, styrenephosphonic acid, α-methylstyrenealkylphosphonic acid and styrenealkylphosphonic acid (hereinafter referred to as “α And a (meth) acrylic acid ester copolymer containing a phosphoric acid group represented by the general formula (A).

As α-methylstyrenephosphonic acid or styrenephosphonic acid, commercially available products or α-methylstyrene or styrene phosphonated can be used.
Phosphonation of styrene can be achieved by introducing a chloromethyl group and then introducing a phosphonic acid group by diethylphosphonate formation and hydrolysis.

  As α-methylstyrene alkylphosphonic acid and styrene alkylphosphonic acid, commercially available products can be used. The alkyl group is preferably an alkyl group having 1 to 2 carbon atoms. As the alkyl group, one bonded to the p-position of styrene or the like can be used.

  Examples of (meth) acrylic acid esters containing a phosphate group used in the present invention include compounds represented by the following general formula (A).

In the formula, R ¹ is H or CH ₃ . R ² is H, CH ₃ or CH ₂ Cl. n is an integer of 1 to 10, preferably 1 to 6.
Of these, the structural formulas of compounds that can be suitably used in the present invention are shown below.

  These compounds include those sold under the trade name Phosmer by Unichemical Co., Ltd., and can be purchased as appropriate. However, the compounds that can be used in the present invention are not limited to these.

  Copolymerization of a monomer such as α-methylstyrenephosphonic acid and a (meth) acrylic acid ester can be performed using general radical polymerization or the like. That is, after adding a light and / or thermal polymerization initiator, polymerization can be performed by heating, ultraviolet light irradiation, or electron beam irradiation.

  The radical polymerization reaction is conducted in a common solvent in which a monomer such as α-methylstyrenephosphonic acid and a (meth) acrylic acid ester containing a phosphate group are dissolved, 2,2-azobisisobutyronitrile, 2, Azo initiators such as 2-azobis (2,4-dimethylvaleronitrile), dimethyl-2,2-azobis (2-methylpropionate), dimethyl-2,2-azobisisobutyrate, lauryl peroxide Polymerization initiators such as peroxide-based initiators such as benzoyl peroxide and tert-butyl peroctoate are used.

  Any reaction solvent can be used as long as these raw materials are basically soluble. Solvents such as alcohols such as methanol, ketones such as acetone, and ethers such as ethylene glycol monomethyl ether can be used. Two or more kinds of mixed solvents may be used.

  The solvent for the reaction system is preferably about 100 to 2000 parts by weight, more preferably 150 to 1000 parts by weight per 100 parts by weight of the raw material components. The polymerization initiator is preferably used in an amount of about 0.01 to 0.5 parts by weight, more preferably about 0.1 parts by weight. If the amount of the solvent and polymerization initiator used is not within the above ranges, the polymer gels and becomes insoluble in various solvents, which causes problems such as the inability to form a film.

  As polymerization conditions, while stirring these reaction solutions, the polymerization is performed at a temperature of 40 ° C. or higher, more preferably at a temperature of 60 ° C. or higher and a solvent boiling point or lower.

  Monomers such as α-methylstyrenephosphonic acid used for copolymerization and the amount of (meth) acrylic acid ester used are (meth) acrylic acid ester with respect to 100 parts by weight of monomer such as α-methylstyrenephosphonic acid. 5 to 400 parts by weight, preferably 10 to 200 parts by weight is desirable.

  In addition, the solid polymer electrolyte according to the present invention is obtained by polymerizing α-methylstyrene substituted with a (N, N-diethylamino) phosphinyl group at the p-position, and then hydrolyzing or oxidizing (N, N-diethylamino). And a solid polymer electrolyte characterized by using a polymer having a phosphinyl group as a proton dissociation group.

Specifically, the second solid polymer electrolyte according to the present invention includes α-methylstyrene having a phosphinic acid group or phosphonic acid group substituted at the p-position represented by the following structural formula (B ₁ ), and a structural formula One or two monomers selected from α-methylstyrene substituted with a phosphinic acid group or phosphonic acid group at the p-position represented by (C ₁ ), and represented by the above general formula (A) (meta ) It contains an acrylic ester copolymer.

  The second method for producing a solid polymer electrolyte of the present invention comprises α-methylstyrene having a (N, N-diethylamino) phosphinyl group substituted at the p-position represented by the following structural formula (B) and the structural formula (C And p-position represented by (N, N-diethylamino) phosphinyl group, one or two monomers selected from α-methylstyrene substituted with (meth) acrylic represented by the above general formula (A) It is characterized by having a step of obtaining a copolymer having a (N, N-diethylamino) phosphinyl group as a proton dissociation group after copolymerization of an acid ester and then hydrolysis or oxidation.

More specifically, the third solid polymer electrolyte according to the present invention includes α-methylstyrene having a phosphinic acid group or phosphonic acid group substituted at the p-position represented by the following structural formula (B ₁ ), and A polymer or copolymer comprising one or two monomer units selected from α-methylstyrene substituted with a phosphinic acid group or a phosphonic acid group at the p-position represented by the structural formula (C ₁ ). It is characterized by.

  The third method for producing a solid polymer electrolyte of the present invention includes α-methylstyrene having a (N, N-diethylamino) phosphinyl group substituted at the p-position represented by the following structural formula (B) and a structural formula (C ), One or two monomers selected from α-methylstyrene substituted with an (N, N-diethylamino) phosphinyl group at the p-position represented by anion polymerization, and then hydrolyzed or oxidized (N , N-diethylamino) phosphinyl group as a proton dissociation group.

In addition, a proton dissociation group shows a phosphonic acid group and a phosphinic acid group.
One or two monomers selected from α-methylstyrene represented by structural formula (B) and structural formula (C) used in the second method for producing a solid polymer electrolyte of the present invention, and a general formula ( The amount of the (meth) acrylic acid ester represented by A) is 5 to (meth) acrylic acid ester with respect to 100 parts by weight of α-methylstyrene represented by structural formula (B) and structural formula (C). 400 parts by weight, preferably 10 to 200 parts by weight is desirable.

  The amount of α-methylstyrene represented by the structural formula (B) and structural formula (C) used in the third method for producing a solid polymer electrolyte of the present invention is 100 weights of the monomer of the structural formula (B). The amount of the monomer represented by the structural formula (C) is 0 to 10,000 parts by weight, preferably 0 to 1000 parts by weight with respect to parts.

For the polymerization of α-methylstyrene in which the (N, N-diethylamino) phosphinyl group is substituted at the p-position, a general radical polymerization or living polymerization method can be used.
In the living polymerization method, the molecular weight can be precisely controlled, and a polymer having a narrow molecular weight distribution can be synthesized.

When using the living polymerization method, it is preferable to sufficiently dry the solvent with a drying agent such as metallic sodium.
When the monomers represented by the structural formulas (B) and (C) are subjected to living polymerization, the optimum reaction conditions such as the concentration of the living polymerization initiator and the organic solvent solution of the monomer change depending on the selection of the functional group of the monomer. Although it is preferable to conduct a preliminary experiment for setting the conditions, it is generally preferable to use about 100 to 10,000 parts by weight, more preferably 400 to 2000 parts by weight of the organic solvent with respect to 100 parts by weight of the monomer component used for polymerization. is there.

  The living polymerization of the monomer is preferably performed using a polymerization initiator. As the polymerization initiator, for example, an organometallic compound is preferable. Specifically, n-butyllithium, sec-butyllithium, tert-butyllithium, sodium naphthalene, anthracene sodium, α-methylstyrenetetramerium sodium, cumylpotassium, cumylcesium Examples thereof include organic alkali metal compounds and the like.

The addition amount of the polymerization initiator can be a normal amount, but the initiator concentration is preferably adjusted to 10 ⁻² to 10 ⁻⁴ mol / liter in the reaction solvent.
Living polymerization is generally performed in an organic solvent. Examples of the organic solvent include aromatic hydrocarbons such as cyclic ethers, aliphatic hydrocarbon solvents, and the like. Specific examples include benzene, toluene, tetrahydrofuran, dioxane, tetrahydropyran, dimethoxyethane, n-hexane, cyclohexane, and the like. Is exemplified. These organic solvents may be used alone or in combination of two or more.

  Furthermore, it is desirable that the living polymerization reaction is carried out while sufficiently stirring the organic solvent solution of the monomer as it is or in a replacement atmosphere with an inert gas such as argon or nitrogen after vacuuming the reaction system. The reaction temperature can be appropriately selected from −100 ° C. to room temperature, and in particular, when a tetrahydrofuran solvent is used, −100 ° C. to 0 ° C., and when a benzene solvent is used, room temperature is preferable. In the living polymerization, the polymerization reaction is usually completed in about 10 minutes to 5 hours.

  After the living polymerization reaction is completed, the reaction is stopped by adding a terminating agent such as methanol, water, or methyl bromide to the obtained reaction mixture solution, and a suitable solvent such as methanol is added to obtain a precipitate. The polymer can be purified and isolated by washing and drying. In general, the polymer after the reaction contains unreacted substances, side-reacted substances and the like as impurities, and it is preferable that the purification treatment is sufficiently performed.

  The polymer thus obtained is monodispersed in terms of molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn) = 1.0 to 1.4). Obtainable. The polymer yield is almost 100% based on the monomer used for the reaction, and the molecular weight (Mw) of this polymer is easily calculated from the weight of the monomer used and the number of moles (molecular weight) of the polymerization initiator. it can. Moreover, Mn and molecular weight distribution can be calculated | required by the said method, and evaluation of molecular weight distribution can evaluate whether the polymer obtained by performing by GPC is the target polymer.

The weight average molecular weight of the polymer and copolymer obtained in the present invention is 3000 to 20000, preferably 5000 to 10,000.
α-Methylstyrene in which the (N, N-diethylamino) phosphinyl group is substituted at the p-position is hydrolyzed or oxidized after polymerization, so that the (N, N-diethylamino) phosphinyl group becomes a phosphinic acid group or phosphonic acid group. Gives a polymer. A polymer having a phosphinic acid group can be obtained by hydrolyzing the (N, N-diethylamino) phosphinyl group with formic acid, hydrochloric acid or the like in a solvent such as dioxane, acetone, acetonitrile, or benzene. Moreover, the polymer which has a phosphonic acid group can be obtained by oxidizing with ozone, hydrogen peroxide, etc.

  An electrolyte membrane is formed from the polymer solution obtained by the above method by a known method. In the case of an electrolyte membrane, the polymer solution is cast on the surface of the substrate and dried to obtain the electrolyte membrane. The film thickness can be adjusted using an air knife, bar coater, doctor blade, metering roll, doctor roll, or the like.

The polymer thus obtained is used as a solid electrolyte membrane, and a fuel cell can be assembled by providing a catalyst, a diffusion layer, and electrodes on both sides of the electrolyte membrane by a known method.
An example of a partial schematic diagram of a fuel cell in the present invention is shown in FIG.

In FIG. 1, electrode catalyst layers 2a and 2b are provided on both surfaces of a polymer electrolyte membrane 1, diffusion layers 3a and 3b are provided on the outside thereof, and electrodes serving also as current collectors are provided on the outside thereof.
The electrode catalyst layer 2a on the fuel electrode side is made of an electrode catalyst having an organic group capable of hydrogen ion dissociation at least on a conductive carbon carrying a platinum catalyst.

  The platinum catalyst used in the present invention is preferably supported on the surface of conductive carbon. The average particle diameter of the supported catalyst is preferably small, and specifically, the average particle diameter is preferably 0.5 nm to 20 nm, more preferably 1 nm to 10 nm. If it is less than 0.5 nm, the activity of the catalyst particles alone is too high, making handling difficult. On the other hand, if the thickness exceeds 20 nm, the surface area of the catalyst decreases and the number of reaction sites decreases, which may reduce the activity.

  Instead of the platinum catalyst, a platinum group metal such as rhodium, ruthenium, iridium, palladium, and osmium, or an alloy of platinum and these metals may be used. In particular, when methanol is used as the fuel, it is preferable to use an alloy of platinum and ruthenium.

  The conductive carbon that can be used in the present invention can be selected from carbon black, carbon fiber, graphite, carbon nanotube, and the like. The average particle diameter is preferably in the range of 5 nm to 1000 nm, and more preferably in the range of 10 nm to 100 nm. However, since agglomeration occurs to some extent during actual use, the particle size distribution may be as wide as 20 nm to 1000 nm or more.

Further in order to carry the above-mentioned catalyst, the specific surface area of the conductive carbon may large to some degree, the BET specific surface area of 50m ² / g~3000m ² / g Further, 100m ² / g~2000m ² / g are preferred.

  A known method can be widely used as a method for supporting the catalyst on the conductive carbon surface. For example, a method is known in which a solution of platinum and other metals is impregnated with conductive carbon, and then these noble metal ions are reduced and supported on the surface of the conductive carbon. Alternatively, a noble metal to be supported may be used as a target and supported on conductive carbon by a vacuum film forming method such as sputtering.

The electrode catalyst produced in this way is singly or mixed with a binder, a polymer electrolyte, a water repellent, conductive carbon, a solvent, and the like, and is in close contact with the polymer electrolyte membrane and a diffusion layer described later.
Diffusion layers 3a and 3b can efficiently introduce hydrogen, reformed hydrogen, methanol, dimethyl ether and oxidant air and oxygen as fuel into the electrode catalyst layer and contact the electrodes to transfer electrons. It is. In general, a conductive porous film is preferable, and carbon paper, carbon cloth, a composite sheet of carbon and polytetrafluoroethylene, or the like is used.

The surface and the inside of the diffusion layer may be coated with a fluorine-based paint and subjected to a water repellent treatment.
The electrodes 4a and 4b can be used without particular limitation as long as they can efficiently supply fuel and oxidant to each diffusion layer and can exchange electrons with the diffusion layer.

  The fuel cell in the present invention is prepared by laminating a polymer electrolyte membrane, an electrode catalyst layer, a diffusion layer, and an electrode as shown in FIG. 1, but the shape thereof is arbitrary and the production method is not particularly limited. Can be used.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention.
For example, the composite solid polymer electrolyte according to the present invention can be used alone, but the composite solid polymer electrolyte according to the present invention can also be used on the surface of another solid polymer electrolyte. .

  Furthermore, the solid polymer electrolyte according to the present invention is particularly suitable as an electrolyte membrane used in electrochemical devices used under harsh conditions such as fuel cells and SPE electrolyzers. It is not limited to, but can also be used as an electrolyte membrane used in various electrochemical devices such as hydrohalic acid electrolyzer, salt electrolyzer, hydrogen and / or oxygen concentrator, humidity sensor, gas sensor and the like. .

Example 1
In a round bottom flask, 180 g of methanol, 10 g of α-methylstyrenephosphonic acid (manufactured by Unichemical Co., Ltd.) and 10 g of acid phosphooxyethyl methacrylate (Hosmer M, Unichemical Co., Ltd.) were placed. The atmosphere was replaced with nitrogen, immersed in an oil bath, heated to 60 ° C. and refluxed. After reaching 60 ° C., 0.1 g of AIBN (2,2′-azobisisobutyronitrile, manufactured by Kishida Chemical Co., Ltd.) was added. After 3 hours, a polymer solution was obtained.

This solution was spread on a Teflon (registered trademark) case, heated from room temperature to 60 ° C., and dried for 12 hours. The film thickness of the obtained film was 0.12 mm. A gold electrode was deposited on this film by ion sputtering, and the conductivity was measured at 50 ° C. in an atmosphere of 90% humidity. The conductivity of this film was 2.5 × 10 ⁻³ Scm ⁻¹ .

Example 2
A round bottom flask was charged with 180 g of methanol, 7 g of styrene phosphonic acid (manufactured by Unichemical Co., Ltd.) and 3 g of acid phosphooxyethyl methacrylate (Hosmer M, Unichemical Co., Ltd.). The atmosphere was replaced with nitrogen, immersed in an oil bath, heated to 60 ° C. and refluxed. After reaching 60 ° C., 0.1 g of AIBN was added. After 3 hours, a polymer solution was obtained.

This solution was spread on a Teflon (registered trademark) case, heated from room temperature to 60 ° C., and dried for 12 hours. The film thickness of the obtained film was 0.15 mm. A gold electrode was deposited on this film by ion sputtering, and the conductivity was measured at 50 ° C. in an atmosphere of 90% humidity. The conductivity of this film was 3.8 × 10 ⁻³ Scm ⁻¹ .

Example 3
In a round bottom flask, 180 g of tetrahydrofuran, 6 g of p- (N, N-diethylamino) -α-methylstyrene (Unichemical Co., Ltd.) and 4 g of acid phosphooxyethyl methacrylate (Phosmer M, Unichemical Co., Ltd.) Put. The atmosphere was replaced with nitrogen, immersed in an oil bath, heated to 60 ° C. and refluxed. After reaching 60 ° C., 0.1 g of AIBN was added. After 3 hours, a polymer solution was obtained. Next, the obtained copolymer solution is hydrolyzed with hydrochloric acid for 1 hour under reflux to polymerize a p- (N, N-diethylamino) group into a phosphinic acid group. Got.

This solution was spread on a Teflon (registered trademark) case, heated from room temperature to 70 ° C. and dried for 12 hours. The film thickness of the obtained film was 0.13 mm. Further, by IR analysis of the obtained film, it was confirmed that no p- (N, N-diethylamino) group remained and all p- (N, N-diethylamino) groups were hydrolyzed. A gold electrode was deposited on this film by ion sputtering, and the conductivity was measured at 50 ° C. in an atmosphere of 90% humidity. The conductivity of this film was 1.8 × 10 ⁻³ Scm ⁻¹ .

Example 4
Under a high vacuum of 10 ⁻⁵ Torr, 250 g of tetrahydrofuran and 4.7 × 10 ⁻⁴ mol of n-butyllithium as a polymerization initiator were charged in a sealed container, and then kept at −78 ° C. To this mixture was added 13 g of p- (N, N-diethylamino) -α-methylstyrene (Unichemical Co., Ltd.) diluted with 30 g of tetrahydrofuran at −78 ° C. The polymer solution was obtained by stirring for 1 hour. Methanol was added to terminate the polymerization. Further, this polymer solution was poured into methanol to precipitate the obtained polymer, and then separated and dried to obtain 11 g of a polymer. 11 g of this polymer was dissolved in 250 g of tetrahydrofuran and oxidized with hydrogen peroxide for 1 hour to obtain a polymer solution in which p- (N, N-diethylamino) groups were oxidized to phosphonic acid groups. .

This solution was spread on a Teflon (registered trademark) case, heated from room temperature to 70 ° C. and dried for 12 hours. The film thickness of the obtained film was 0.08 mm. Further, by IR analysis of the obtained film, it was confirmed that no p- (N, N-diethylamino) group remained and all p- (N, N-diethylamino) groups were oxidized. A gold electrode was deposited on this film by ion sputtering, and the conductivity was measured at 50 ° C. in an atmosphere of 90% humidity. The conductivity of this film was 4.2 × 10 ⁻³ Scm ⁻¹ .

Comparative Example 1
A round bottom flask was charged with 180 g of methanol and 10 g of acid phosphooxyethyl methacrylate (Phosmer M, manufactured by Unichemical Co., Ltd.). The atmosphere was replaced with nitrogen, immersed in an oil bath, heated to 60 ° C. and refluxed. After reaching 60 ° C., 0.1 g of AIBN was added. After 3 hours, a polymer solution was obtained.

This solution was spread on a Teflon (registered trademark) case, heated from room temperature to 60 ° C., and dried for 12 hours. The film thickness of the obtained film was 0.17 mm. A gold electrode was deposited on this film by ion sputtering, and the conductivity was measured at 50 ° C. in an atmosphere of 90% humidity. The conductivity of this film was 8.0 × 10 ⁻⁴ Scm ⁻¹ .
Compared with the Examples, the film obtained in Comparative Example 1 was inferior in flexibility and low in conductivity.

Comparative Example 2
Using an electron beam irradiation apparatus (Iwasaki Electric Co., Ltd., I Electron Beam EC250 / 15 / 180L), 150 kV, 200 kGy electron beam is dried on a 50 μm-thick tetrafluoroethylene (PTFE Nichias, Naflon) film. Irradiation was performed under ice cooling to generate radicals inside the tetrafluoroethylene film. This tetrafluoroethylene membrane was quickly immersed in an excess amount of styrene monomer, and the inside of the reaction vessel was purged with nitrogen, followed by heat treatment at 60 ° C. for 60 hours to introduce polystyrene graft chains.

  After the reaction, the non-grafted components (styrene monomer and homopolymer) were extracted and removed by refluxing with chloroform and dried under reduced pressure at 80 ° C. to obtain a polystyrene graft PTFE membrane.

  Next, the polystyrene graft PTFE membrane is immersed in a mixed solution of 30 parts by weight of chloromethyl methyl ether and 70 parts by weight of carbon disulfide, and 3 parts by weight of anhydrous zinc chloride is added and reacted at room temperature for 240 hours with stirring. A chloromethyl group was introduced into the styrene unit. After the reaction, the membrane was washed with ethanol and dried under reduced pressure at 80 ° C. to obtain a chloromethylated polystyrene graft PTFE membrane.

  Next, the chloromethylated polystyrene graft PTFE membrane was immersed in an excessive amount of triethyl phosphite, and the mixture was heated and refluxed for 24 hours to introduce diethylphosphonate groups into chloromethylstyrene units. After the reaction, the membrane was washed with ethanol and dried under reduced pressure at 80 ° C. to obtain a diethylphosphonated polystyrene graft PTFE membrane.

  Further, the diethylphosphonate group was hydrolyzed by refluxing the diethylphosphonated polystyrene graft PTFE membrane in 10N hydrochloric acid for 24 hours. After the reaction, the obtained phosphonic acid type polystyrene graft PTFE membrane was washed with distilled water and dried under reduced pressure at 80 ° C. to obtain a phosphonic acid type ETFE-g-PSt membrane.

  In addition, since phosphonic acid groups are quantitatively introduced into chloromethylstyrene units, the chloromethylation rate of styrene is determined from the weight change of the membrane before and after the reaction. The rate was calculated.

W: membrane weight after chloromethylation treatment W _PSt : weight of polystyrene grafted PTFE membrane (g)
W _PTFE : PTFE membrane weight (g)
The phosphonic acid group introduction rate calculated by Formula 1 was 89%.

A gold electrode was deposited on this film by ion sputtering, and the conductivity was measured at 50 ° C. in an atmosphere of 90% humidity. The conductivity of this film was 6.5 × 10 ⁻⁴ Scm ⁻¹ .
Compared to the Examples, Comparative Example 2 requires many steps to obtain a phosphonic acid type film, and requires a long time for production. And the electrical conductivity was low.

Subsequently, for the polymer electrolytes produced in Example 1 and Comparative Example 1, a fuel cell was produced by the following procedure and a durability test was performed.
[Create electrode catalyst layer]
As the diffusion layer, water-repellent-treated carbon paper with a thickness of 0.1 mm (TGP-H-30, manufactured by Toray Industries, Inc.) was used. In the electrode catalyst layer on the anode side (negative electrode), 1 g of carbon (manufactured by Tanaka Kikinzoku) carrying 60 wt% Pt-Ru catalyst (Pt: Ru = 1: 1, atomic ratio) and 5 wt% Nafion solution ( A paste sufficiently mixed with 5 g of Aldrich) was used.

This catalyst paste was applied onto carbon paper using a bar coater to a thickness of 130 μm and dried under reduced pressure at room temperature. The amount of catalyst supported was 5 mg / cm ² .
Carbon paper treated with water repellency was also used for the diffusion layer on the cathode side (positive electrode). A paste in which 1 g of carbon (manufactured by Tanaka Kikinzoku Co., Ltd.) carrying 60 wt% of Pt catalyst and 5 g of 5 wt% of Nafion solution was sufficiently mixed was used for the electrode catalyst layer on the cathode side. This catalyst paste was applied onto carbon paper using a bar coater to a thickness of 130 μm and dried under reduced pressure at room temperature. The amount of catalyst supported was 5 mg / cm ² .

[Membrane electrode assembly preparation]
The carbon paper with the catalyst layer of an anode and a cathode was arrange | positioned on both surfaces of the polymer electrolyte, and it hot-pressed for 10 minutes at 90 degreeC and 9.8 MPa, and obtained the membrane electrode assembly.

The membrane electrode assembly obtained in Example 1 and Comparative Example 1 was sandwiched between separators, and the fuel cell characteristics were evaluated using a fuel cell evaluation device (manufactured by Toyo Technica Co., Ltd.).
A 5 wt% aqueous methanol solution is supplied to the fuel electrode side at 10 ml / min, and air at normal pressure is supplied to the oxidizer electrode side at 100 ml / min, and electricity is generated while keeping the entire cell at 75 ° C. It was.

Table 1 shows the terminal voltages at the initial stage and after 200 hours when discharged at a current density of 0.25 A / cm ² .

  As is clear from the results shown in Table 1, it can be seen that the fuel cell made of the polymer electrolyte of Example 1 shows a stable voltage over a long period of time. In contrast, the fuel cell made of the polymer electrolyte of Comparative Example 1 did not generate any power after 20 hours of operation.

  As described above in detail, the solid polymer electrolyte according to the present invention includes a monomer having a functional group containing phosphorus such as a phosphonic acid group as a functional group having a function of suppressing an oxidation reaction and a monomer having a phosphate group. An electrolyte obtained by copolymerizing (phosmer) is used. Furthermore, since the main part is constituted by the hydrocarbon-based solid polymer electrolyte, there is an effect that an electrolyte having such excellent oxidation resistance and strength can be obtained at a low cost. Further, by using these composite solid polymer electrolytes in electrochemical devices, particularly fuel cells and SPE electrolyzers, there is an effect that it is possible to provide these devices that are inexpensive and excellent in durability. .

  In the method for producing a solid polymer electrolyte according to the present invention, a polymer obtained by a living polymerization method can be used for the polymer electrolyte. The living polymerization method can provide a high-performance solid polymer electrolyte, such as a block copolymer, in which molecular weight and structure are strictly controlled.

  Since the solid polymer electrolyte of the present invention is inexpensive and excellent in oxidation resistance and durability, it is used for electrochemical devices used under harsh conditions such as solid polymer fuel cells and SPE electrolyzers. be able to.

It is a partial schematic diagram showing an example of a fuel cell of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polymer electrolyte membrane 2a Electrode catalyst layer 2b Electrode catalyst layer 3a Diffusion layer 3b Diffusion layer 4a Electrode (fuel electrode)
4b Electrode (Air electrode)

Claims (7)

one or more monomers selected from α-methylstyrenephosphonic acid, styrenephosphonic acid, α-methylstyrenealkylphosphonic acid and styrenealkylphosphonic acid, and (meth) acrylic acid ester represented by the following general formula (A): A solid polymer electrolyte comprising a copolymer.

(In the formula, R ₁ is H or CH ₃ , R ₂ is H, CH ₃ or CH ₂ Cl, and n is an integer of 1 to 10.) one or more monomers selected from α-methylstyrenephosphonic acid, styrenephosphonic acid, α-methylstyrenealkylphosphonic acid and styrenealkylphosphonic acid, and (meth) acrylic acid ester represented by the following general formula (A): A method for producing a solid polymer electrolyte, comprising a step of obtaining a copolymer by copolymerization.

(In the formula, R ₁ is H or CH ₃ , R ₂ is H, CH ₃ or CH ₂ Cl, and n is an integer of 1 to 10.) One or two monomers selected from α-methylstyrene represented by the following structural formula (B ₁ ) and α-methylstyrene represented by the structural formula (C ₁ ), and the following general formula (A) A solid polymer electrolyte comprising a copolymer of (meth) acrylic acid ester shown.

(In the formula, R ₁ is H or CH ₃ , R ₂ is H, CH ₃ or CH ₂ Cl, and n is an integer of 1 to 10.) One or two monomers selected from α-methylstyrene represented by the following structural formula (B) and α-methylstyrene represented by the structural formula (C), and represented by the following general formula (A) ( A solid polymer electrolyte comprising a step of obtaining a copolymer having a (N, N-diethylamino) phosphinyl group as a proton dissociation group after copolymerization of a (meth) acrylate ester and hydrolysis or oxidation Production method.

(In the formula, R ₁ is H or CH ₃ , R ₂ is H, CH ₃ or CH ₂ Cl, and n is an integer of 1 to 10.) A polymer or copolymer comprising one or two monomer units selected from α-methylstyrene represented by the following structural formula (B ₁ ) and α-methylstyrene represented by the structural formula (C ₁ ): A solid polymer electrolyte comprising:

One or two monomers selected from α-methylstyrene represented by the following structural formula (B) and α-methylstyrene represented by the structural formula (C) are subjected to anionic living polymerization, followed by hydrolysis or oxidation. And a step of obtaining a polymer or copolymer having a (N, N-diethylamino) phosphinyl group as a proton dissociation group.

  A solid polymer fuel cell comprising the solid polymer electrolyte according to claim 1.

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