JP2000011756A - High-durability solid high molecular electrolyte - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high molecular electrolyte that has oxidation resistance which is equal to or more than that of a fluorine electrolyte or practically sufficient and can be manufactured at low cost by mixing a high molecular compound having an electrolyte group and a hydrocarbon part with a compound containing phosphorus. SOLUTION: Because a high molecular compound having an electrolyte group and a hydrocarbon part is mixed with a compound containing phosphorus, the oxidation resistance of the hydrocarbon part is improved, so that a solid high molecular electrolyte having high durability can be provided. In addition, because the high molecular compound having the hydrocarbon part is relatively less expensive, the high molecular electrolyte having oxidation resistance which is equal to or more than that of a fluorine electrolyte or practically sufficient can be manufactured at low cost by mixing a functional group containing phosphorus in a range equal to or more than 0.1 mol.% of the whole electrolyte group. If it is used, for instance, as an electrolyte film for a solid high molecular type fuel cell, the solid high molecular type fuel cell excellent in durability can be manufactured at low cost and its effect is extremely great from an industrial view point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a highly durable solid polymer electrolyte, and more particularly to a fuel cell, water electrolysis,
The present invention relates to a highly durable solid polymer electrolyte excellent in oxidation resistance and the like suitable for an electrolyte membrane used for hydrohalic acid electrolysis, salt electrolysis, oxygen concentrator, humidity sensor, gas sensor and the like.

[0002]

2. Description of the Related Art A solid polymer electrolyte is a solid polymer material having an electrolyte group such as a sulfonic acid group in a polymer chain.
Since it has the property of firmly binding to specific ions and selectively permeating cations or anions, it is formed into particles, fibers, or membranes, and is used for electrodialysis, diffusion dialysis, battery membranes, etc. Are used for various purposes.

[0003] In particular, a fluorine-based electrolyte membrane typified by a perfluorosulfonic acid membrane known under the trade name of Nafion (registered trademark, manufactured by DuPont) has extremely high chemical stability, so that it is subjected to severe conditions. It has been awarded as an electrolyte membrane used in.

For example, a reformed gas fuel cell is provided with a pair of electrodes on both surfaces of a proton conductive solid polymer electrolyte membrane,
Hydrogen gas obtained by reforming low molecular hydrocarbons such as methane and methanol is supplied as fuel gas to one electrode (fuel electrode), and oxygen gas or air is used as an oxidant to a different electrode (air electrode). Supply and obtain an electromotive force. Water electrolysis is a method for producing hydrogen and oxygen by electrolyzing water using a solid polymer electrolyte membrane.

In the case of a fuel cell or water electrolysis, peroxide is generated in a catalyst layer formed at the interface between the solid polymer electrolyte membrane and the electrode, and the generated peroxide is diffused to form peroxide radicals. Since a degradation reaction occurs, a hydrocarbon-based electrolyte membrane having poor oxidation resistance cannot be used. Therefore, a perfluorosulfonic acid membrane having high proton conductivity is generally used in fuel cells and water electrolysis.

[0006] Salt electrolysis is a method for producing sodium hydroxide, chlorine and hydrogen by electrolyzing an aqueous solution of sodium chloride using a solid polymer electrolyte membrane. In this case, since the solid polymer electrolyte membrane is exposed to chlorine and a high-temperature, high-concentration aqueous sodium hydroxide solution, it is not possible to use a hydrocarbon-based electrolyte membrane having poor resistance to these. Therefore, the solid polymer electrolyte membrane for salt electrolysis is generally resistant to chlorine and high-temperature, high-concentration sodium hydroxide aqueous solution, and furthermore, the surface thereof is partially carbonized to prevent back diffusion of generated ions. A perfluorosulfonic acid membrane into which an acid group has been introduced is used.

Meanwhile, a fluorine-based electrolyte represented by a perfluorosulfonic acid membrane has a very high chemical stability because of having a C—F bond, and is used for the above-mentioned fuel cell.
In addition to solid polymer electrolyte membranes for water electrolysis or salt electrolysis, they are also used as solid polymer electrolyte membranes for hydrohalic acid electrolysis.Furthermore, utilizing proton conductivity, humidity sensors, gas sensors, oxygen sensors It is widely applied to concentrators and the like.

[0008] However, fluorine-based electrolytes have the disadvantage that they are difficult to produce and are very expensive. for that reason,
Fluorine-based electrolyte membranes are used for special applications such as solid polymer fuel cells for space or military use, and are difficult to apply to consumer applications such as solid polymer fuel cells as low-emission power sources for automobiles. I was doing it.

As a study example of a polymer electrolyte other than a fluorine-based electrolyte, see Swiss Appl. 02 636/93
And -6, a hydrocarbon-based electrolyte such as a cross-linked polystyrene graft resin film into which a sulfonic acid group is introduced, and a polyether sulfone resin into which a sulfonic acid type is introduced as disclosed in JP-A-10-45913.

[0010] These hydrocarbon-based electrolyte membranes are advantageous in that they are easy to manufacture and low in cost, as compared with fluorine-based electrolyte membranes represented by Nafion. But on the other hand,
As described above, the hydrocarbon-based electrolyte membrane has a problem that oxidation resistance is low. The reason that oxidation resistance is low is that hydrocarbon compounds generally have low durability against radicals,
This is because an electrolyte having a hydrocarbon skeleton easily undergoes a degradation reaction due to radicals (an oxidation reaction due to peroxide radicals).

Therefore, various attempts have hitherto been made to obtain a solid polymer electrolyte membrane having oxidation resistance equal to or higher than that of a fluorine-based electrolyte membrane and which can be manufactured at low cost. For example, Japanese Patent Application Laid-Open No. 9-102322 discloses a sulfone comprising a main chain formed by copolymerization of a fluorocarbon vinyl monomer and a hydrocarbon vinyl monomer, and a hydrocarbon side chain having a sulfonic acid group. Acid type polystyrene-graft-ethylene-tetrafluoroethylene copolymer (ETFE) membranes have been proposed.

Further, US Pat. No. 4,012,303 and US Pat. No. 4,605,685 disclose α, β in films formed by copolymerization of a fluorocarbon vinyl monomer and a hydrocarbon vinyl monomer. A sulfonic acid type poly (trifluorostyrene) -graft-ETFE membrane has been proposed in which a sulfonic acid group is introduced into the polymer by graft polymerization of .beta .-. Beta.-trifluorostyrene to form a solid polymer electrolyte membrane. This is based on the assumption that the chemical stability of the polystyrene side chain into which the sulfonic acid group is introduced is not sufficient, and instead of styrene, α, which is obtained by fluorinating styrene,
β, β-trifluorostyrene is used.

The above-mentioned Swiss patent Appl. 02 63
The 6 / 93-6 cross-linked sulfonic acid group-introduced polystyrene graft resin membrane suppresses the elimination of low molecular weight components during oxidative deterioration by introducing cross-links into the polystyrene resin, which is a hydrocarbon part that is easily degraded. It can also be considered as an attempt to improve durability when used as an electrolyte membrane for a fuel cell.

[0014]

Problems to be Solved by the Invention
No. 2 sulfonic acid type polystyrene disclosed in
The graft-ETFE membrane is inexpensive, has sufficient strength as a solid polymer electrolyte membrane for a fuel cell, and can improve the electrical conductivity by increasing the amount of sulfonic acid groups introduced.

However, in the sulfonic acid type polystyrene-graft-ETFE membrane, the main chain portion formed by copolymerization of a fluorocarbon vinyl monomer and a hydrocarbon vinyl monomer has high oxidation resistance, but a sulfonic acid group is introduced. The side chain portion is a hydrocarbon polymer that is susceptible to oxidative degradation. Therefore, when this is used for a fuel cell, there is a problem that the oxidation resistance of the whole membrane is insufficient and the durability is poor.

On the other hand, the sulfonic acid type poly (trifluorostyrene) -graft-ETFE membrane disclosed in US Pat. No. 4,012,303 and the like has a side chain composed of a fluoropolymer. It seems that the above problem has been solved.

However, α, which is a raw material for the side chain portion,
Since β, β-trifluorostyrene is difficult to synthesize, there is a problem of cost as in the case of Nafion described above when considering application as a solid polymer electrolyte membrane for a fuel cell. Further, α, β, β-trifluorostyrene tends to deteriorate, so that it is difficult to handle and has low polymerization reactivity. Therefore, there remains a problem that the amount that can be introduced as a graft side chain is low, and the conductivity of the obtained film is low.

The durability of the crosslinked sulfonic acid type polystyrene graft membrane is higher than that of the sulfonic acid type polystyrene graft membrane into which no crosslink is introduced.
By increasing the physical bond, it is possible to prevent the desorption of the components caused by the deterioration, and the durability itself of the polymer has not been improved and cannot be said to be an essential improvement.

An object of the present invention is to provide a highly durable solid polymer electrolyte which has oxidation resistance equal to or higher than that of a fluorine-based electrolyte, or has sufficient oxidation resistance for practical use, and can be manufactured at low cost. It is in.

[0020]

In order to solve the above problems, a highly durable solid polymer electrolyte according to the present invention comprises mixing a polymer compound having an electrolyte group and a hydrocarbon moiety with a compound containing phosphorus. The gist of the invention is that it can be obtained by doing so.

In this case, in the polymer compound having a hydrocarbon part, it is necessary that an electrolyte group such as a sulfonic acid group or a carboxylic acid group is introduced into a portion into which the electrolyte group can be introduced. Further, the compound containing phosphorus includes various compounds containing a functional group containing trivalent phosphorus and / or a functional group containing pentavalent phosphorus. Further, as the compound containing phosphorus, a compound having a phosphonic acid group is particularly preferable.

The highly durable solid polymer electrolyte according to the present invention is obtained by mixing an inexpensive polymer compound having an electrolyte group and a hydrocarbon moiety with a compound containing phosphorus. Since the functional group containing phosphorus is introduced into the electrolyte, the functional group containing phosphorus suppresses the oxidative deterioration reaction of the polymer compound having a hydrocarbon portion. This makes it possible to obtain an inexpensive highly durable solid polymer electrolyte having oxidation resistance equal to or higher than that of the fluorine-based electrolyte or sufficient for practical use.

[0023]

Embodiments of the present invention will be described below in detail. The highly durable solid polymer electrolyte according to the present invention, a polymer compound having an electrolyte group and a hydrocarbon portion,
It is obtained by mixing with a compound containing phosphorus.

The high molecular compound having a hydrocarbon moiety constitutes a part of the base material of the highly durable solid polymer electrolyte, and C—H is attached to one of the molecular chains constituting the high molecular compound.
It means a compound having a bond and capable of introducing an electrolyte group. The electrolyte group refers to a functional group having an electrolyte ion, such as a sulfonic acid group and a carboxylic acid group. Further, in the polymer compound having a hydrocarbon portion, the above-described electrolyte group is introduced at a predetermined introduction rate to a portion into which the electrolyte group can be introduced.

Specific examples of the high molecular compound having a hydrocarbon moiety include polyether sulfone resin, polyether ether ketone resin, linear phenol-formaldehyde resin, cross-linked phenol-formaldehyde resin, linear polystyrene resin, and cross-linked polystyrene resin. Polystyrene resin, linear poly (trifluorostyrene) resin, crosslinked (trifluorostyrene) resin, poly (2,3-diphenyl-)
1,4-phenylene oxide) resin, poly (allyl ether ketone) resin, poly (arylene ether sulfone)
Resin, poly (phenylquinosan phosphorus) resin, poly (benzylsilane) resin, polystyrene-graft-ethylene-tetrafluoroethylene resin, polystyrene-graft-polyvinylidene fluoride resin, polystyrene-graft-tetrafluoroethylene resin and the like are exemplified. .

Among them, an ethylene tetrafluoroethylene resin represented by a polystyrene-graft-ethylenetetrafluoroethylene resin having an ethylene tetrafluorostyrene resin as a main chain and a hydrocarbon polymer capable of introducing an electrolyte group as a side chain. Graft copolymers, polyethersulfone resins and polyetheretherketone resins are inexpensive and have sufficient strength when thinned,
In addition, since the conductivity can be easily controlled by adjusting the type and the amount of the electrolyte group, it is particularly suitable as a polymer compound having a hydrocarbon moiety.

The compound containing phosphorus means a substance containing a functional group containing phosphorus, a compound having a functional group containing phosphorus, and a compound having a functional group containing phosphorus in a main chain or a side chain. Both high molecular compounds are applicable. Further, the functional group containing phosphorus includes a functional group containing trivalent phosphorus and a functional group containing pentavalent phosphorus, and the “functional group containing phosphorus” in the present invention includes trivalent and trivalent phosphorus. Both pentavalent functional groups are included. These phosphorus-containing functional groups should be represented by the following general formulas (functional groups containing trivalent phosphorus) and chemical formulas 2 (functional groups containing pentavalent phosphorus). Can be.

[0028]

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[0029]

Embedded image

In the formulas (1) and (2),
x, y, and z take a value of 0 or 1. In the formulas (1) and (2), R ₁ , R ₂ and R ₃ represent a hydrocarbon compound having a linear, cyclic or branched structure represented by the general formula C _m H _n , or fluorine, It is a halogen atom such as chlorine or bromine or a hydrogen atom. Further, in the formulas 1 and 2, when y or z is 1, R ₂ or R ₃ may be a metal atom.

Specific examples of the functional group containing phosphorus include a phosphonic acid group, a phosphonate ester group, a phosphite group, phosphoric acid, a phosphoric ester, and the like. Among them, a phosphonic acid group is particularly suitable as a functional group containing phosphorus because it is inexpensive and can impart high oxidation resistance to a polymer compound having a hydrocarbon moiety.

Specific examples of the compound containing phosphorus include:
Polyvinyl sulfonate or a polyether sulfone resin, a polyether ether ketone resin, a linear phenol-formaldehyde resin, a crosslinked phenol-formaldehyde resin, a linear polystyrene resin, a crosslinked polystyrene resin, Chain type poly (trifluorostyrene) resin, crosslinked type (trifluorostyrene) resin, poly (2,3-diphenyl-1,4)
-Phenylene oxide) resin, poly (allyl ether ketone) resin, poly (arylene ether sulfone) resin,
Examples thereof include poly (phenylquinosan phosphorus) resin, poly (benzylsilane) resin, polystyrene-graft-ethylene-tetrafluoroethylene resin, polystyrene-graft-polyvinylidene fluoride resin, and polystyrene-graft-tetrafluoroethylene resin.

The method of mixing the high molecular compound having an electrolyte group and a hydrocarbon moiety with the compound containing phosphorus is not particularly limited, and various methods can be used. For example, a dope or a blend by a solution may be used. When both a polymer compound having an electrolyte group and a hydrocarbon portion and a compound containing phosphorus are heat-meltable, a blend by heat melting may be used.

Further, by uniformly mixing a polymer containing an electrolyte group and a hydrocarbon moiety with a compound containing phosphorus, a structure in which the compound containing phosphorus is uniformly dispersed throughout the solid polymer electrolyte may be obtained. Good. Alternatively, the main part of the solid polymer electrolyte is composed only of the polymer compound having the electrolyte group and the hydrocarbon part, and only the part where the oxidation resistance is required is obtained by combining the polymer compound having the electrolyte group and the hydrocarbon part with phosphorus. And a mixture with the compound.

For example, in an environment where radicals are randomly generated in the membrane, such as when the solid polymer electrolyte membrane is heated in a state of being immersed in a peroxide solution, a high polymer having an electrolyte group and a hydrocarbon portion is used. A structure in which a molecular compound and a compound containing phosphorus are uniformly mixed, and a compound containing phosphorus is uniformly dispersed in a solid polymer electrolyte membrane is effective.

On the other hand, peroxide is generated in the catalyst layer on the surface of the membrane, such as an electrolyte membrane for water electrolysis or a fuel cell, and the generated peroxide is diffused into peroxide radicals to cause a deterioration reaction. In an awake environment, the phosphorus-containing compound need not be uniformly dispersed in the film. In this case, by doping the polymer containing an electrolyte group and a hydrocarbon moiety with a compound containing phosphorus, only the surface portion of the film where the oxidative degradation reaction is the most intense is subjected to a high concentration having an electrolyte group and a hydrocarbon moiety. The mixture may be a mixture of a molecular compound and a compound containing phosphorus.

Alternatively, a film-shaped molded article comprising a mixture of a polymer containing an electrolyte group and a hydrocarbon part and a compound containing phosphorus is placed between an electrolyte consisting only of a polymer compound having an electrolyte group and a hydrocarbon part and an electrode. Is also considered effective for maintaining the performance of the electrolyte membrane.

The type and amount of the electrolyte group introduced into the polymer compound having a hydrocarbon moiety, or the mixing ratio between the compound containing phosphorus and the polymer compound having the electrolyte group and the hydrocarbon moiety depends on the conductivity. What is necessary is just to adjust according to the characteristics required for a solid polymer electrolyte, such as rate and oxidation resistance.

That is, the oxidation resistance increases as the amount of the functional group containing phosphorus increases. However, since the functional group containing phosphorus is a weakly acidic group, as the amount of introduction increases,
The conductivity of the entire material is reduced. Therefore, when only the oxidation resistance is a problem and it is used for an application in which high conductivity is not required, the mixing ratio of the phosphorus-containing compound to the polymer compound having the electrolyte group and the hydrocarbon part can be increased. I just need.

On the other hand, when high conductivity characteristics are required in addition to high oxidation resistance as in fuel cells and water electrolysis,
The compound containing phosphorus and the high molecular compound having a hydrocarbon moiety into which a strong acid group such as a sulfonic acid group has been introduced may be mixed at a predetermined ratio. When high resistance to chlorine, high temperature, and high concentration sodium hydroxide aqueous solution is required as in the case of salt electrolysis and at the same time it is necessary to prevent reverse diffusion of ions, a compound containing phosphorus and a sulfonic acid What is necessary is just to mix at predetermined ratio the high molecular compound which has the hydrocarbon part which introduce | transduced the group and the carboxylic acid group.

However, if the introduction amount of the functional group containing phosphorus is less than 0.1 mol% of the total electrolyte groups, the effect of improving the oxidation resistance becomes insufficient. Therefore, the introduction amount of the functional group containing phosphorus needs to be 0.1 mol% or more of the total electrolyte groups. In particular, in the case of a solid polymer electrolyte used under severe conditions such as fuel cell, water electrolysis, and salt electrolysis, the functional group containing phosphorus is preferably at least 5 mol%.

As described in detail above, the highly durable solid polymer electrolyte according to the present invention comprises a polymer compound having an electrolyte group and a hydrocarbon moiety, and a phosphonic acid group having a function of suppressing an oxidation reaction. And a compound having a phosphorus-containing functional group.

There has been no example of using a phosphoric acid or a phosphonic acid compound for the purpose of improving the oxidation resistance of a solid polymer electrolyte. By mixing a polymer compound having an electrolyte group and a hydrocarbon portion with a compound containing phosphorus, the oxidation resistance of the polymer compound having a hydrocarbon portion can be improved. It was found for the first time.

However, the details of the mechanism are unknown. Presumably, by mixing a compound having a functional group containing phosphorus, the oxidation resistance of the entire solid polymer electrolyte is improved because the peroxide in the system is changed to a peroxide radical by heat or ions. It is considered that the reaction was inhibited by a functional group containing phosphorus.

(Example 1) Sulfonic acid type graft type electrolyte membrane doped with polyvinyl phosphonic acid First, a sulfonic acid type graft type electrolyte membrane was prepared according to the following procedure. That is, an electron beam of 2 MeV and 20 kGy is applied to an ethylene-tetrafluoroethylene copolymer film having a thickness of 50 μm and a size of 50 mm × 50 mm (hereinafter, referred to as “the film”).
This was referred to as “ETFE film”) under dry ice cooling to generate radicals inside the ETFE film.

The ETFE film was stored under cooling with dry ice, returned to room temperature, immediately immersed in an excessive amount of styrene monomer, and the inside of the reaction vessel was replaced with nitrogen.
For 60 hours to introduce a polystyrene graft chain. After the reaction, non-grafted components (styrene monomer and homopolymer) were extracted and removed by reflux treatment with chloroform, and dried under reduced pressure at 80 ° C. to obtain a polystyrene-graft-ETFE membrane (hereinafter, referred to as a “polystyrene-graft-ETFE membrane”) having a graft ratio of 85%. Is referred to as “ETFE-g-PSt film”).

The obtained ETFE-g-PSt film was immersed in a mixed solution of 30 parts by weight of chlorosulfonic acid and 70 parts by weight of tetrachloroethane at room temperature for 1 hour to introduce a chlorosulfone group into the styrene unit of the film. . After the reaction, the membrane was washed with ethanol to remove unreacted components to obtain an ETFE-g-PSt membrane into which a chlorosulfonic acid group was introduced.

This film was immersed in a 1N aqueous solution of potassium hydroxide and heated under reflux for 1 hour to hydrolyze chlorosulfonic acid groups. Further, the mixture was boiled for 1 hour using 1N sulfuric acid to perform proton exchange of sulfonic acid groups. The obtained membrane was washed with distilled water and dried under reduced pressure at 80 ° C. to obtain an equivalent weight of 410 g / eq sulfonic acid type ET.
An FE-g-PSt film was obtained. In addition, the graft ratio of the obtained sulfonic acid type ETFE-g-PSt film was calculated by the following equation (1).

[0049]

## EQU1 ## Graft ratio (%) = (W_ETFE-g-PSt
-W_ETFE) X100 / W _ETFE Where W_ETFE-g-PSt： Film after grafting reaction
Weight (g), W_ETFE : Membrane weight before reaction (g)

The equivalent weight EW was measured according to the following procedure. That is, 0.1 to 0.2 g of the dried film was added to 20 ml of a 0.1 N aqueous sodium hydroxide solution at room temperature.
After immersion for a period of time, the phosphonic acid groups in the membrane were exchanged with sodium. At the same time, an aqueous sodium hydroxide solution to which no membrane was added was similarly prepared and used as a blank.

After the immersion, the membrane was taken out of the sodium hydroxide solution, the membrane was washed with distilled water, and the washing solution was added to the immersion liquid to obtain a titration sample. Automatic titrator (commercially available from Hiranuma)
The sample and the blank were titrated with 0.5N hydrochloric acid using (Tite T-900), the end point was determined from the inflection point of the titration curve, and the EW of the film was calculated by the following equation (2).

[0052]

EW (g / eq) = W / ((Q _blank −Q
_sample) /1000×0.5×F _{HC l)} where, W: weight of the film _{(g), Q blank:} drops against the blank quantitative _{(ml), Q sample:} drops against sample quantifying _{(ml), F HCl: 0} . 5N hydrochloric acid titer

Next, the obtained sulfonic acid type ETFE-g
The -PSt film was immersed in an excessive amount of a 10% aqueous solution of polyvinylphosphonic acid (manufactured by General Science Corporation), and heated and refluxed for 1 hour. After the treatment, the membrane is washed with water at room temperature, dried under reduced pressure, and polyvinylphosphonic acid is added at 10 wt%.
A doped sulfonic acid type ETFE-g-PSt film was obtained.

(Comparative Example 1) Sulfonic acid-type graft-type electrolyte membrane
Following the same procedure as in Example 1, the equivalent weight was 410 g / eq.
A sulfonic acid type ETFE-g-PSt film was obtained.

The sulfonic acid type ETFE-g-PSt film doped with polyvinyl phosphonic acid obtained in Example 1 and the sulfonic acid type ETFE-g-PS film obtained in Comparative Example 1
The oxidation resistance of the t film was evaluated. The oxidation resistance of the film was determined by adding about 100 mg of the film to 50 ml of 3% hydrogen peroxide solution, adding 20 ppm of ferric chloride, heating and refluxing, and measuring the weight change of the film after a predetermined time. It was evaluated by: Table 1 shows the results.

[0056]

[Table 1]

The sulfonic acid type ETFE-g-PSt film (Comparative Example 1) was decomposed in an oxidation resistance test for 10 minutes and the initial weight was 3%.
It decreased to 8%. The film after the oxidation resistance test was in a state where the hydrocarbon chain portion (polystyrene graft chain) was completely eliminated due to the oxidative deterioration.

On the other hand, the sulfonic acid type ETFE-g-PSt film doped with polyvinylphosphonic acid (Example 1) shows almost no change in weight even when treated under the same conditions for 2 hours, and is transparent. A uniform film state was maintained.

From the above results, it was clarified that the oxidation resistance of the hydrocarbon-based electrolyte membrane was improved by doping the hydrocarbon-based electrolyte membrane with a component having a phosphonic acid group.

Comparative Example 2 Sulfonic Acid Type Polyether Sulfone Membrane Polyether Sulfone (Scientific Pol)
ymer Products, Inc. Company. Less than,
10 g of this was called "PES") was added to 100 ml of concentrated sulfuric acid, and 90 g of chlorosulfonic acid (18 times the amount of the polyethersulfone unit) was added dropwise at room temperature under a nitrogen stream in 2 hours, and further reacted at room temperature for 1 hour. Was done. After the reaction, the reaction solution that became a homogeneous solution was dropped into 3 liters of distilled water to precipitate sulfonated PES, which was collected by filtration.

Further, the mixture was heated and refluxed with a 1N aqueous solution of potassium hydroxide for 1 hour to completely hydrolyze it, and then heated and refluxed with 1N hydrochloric acid for 1 hour to effect proton exchange. After washing with distilled water, it was dried at 80 ° C. under reduced pressure to obtain a sulfonated PES.

A 5% DMF solution of the obtained sulfonated PES was cast-coated on a glass substrate, dried at 150 ° C. under reduced pressure to remove the solvent, and formed into a film.
A sulfonic acid type PES membrane of 0 g / eq was obtained.

Example 2 10 g of phosphonic acid type polyethersulfone / sulfonic acid type polyethersulfone blend membrane PES was added to 100 ml of carbon disulfide, 150 ml of chloromethyl methyl ether and 10 g of anhydrous zinc chloride were added. Reaction was carried out for a time to introduce a chloromethyl group into the phenyl unit. After the reaction, the reaction solution that had become a homogeneous solution was dropped into 3 liters of methanol to precipitate chloromethylated PES, which was collected by filtration. After repeating this washing operation three times, the resultant was dried under reduced pressure at 80 ° C. to obtain chloromethylated PES.

A 5% solution of chloromethylated PES in diethyl carbitol (hereinafter referred to as “DEC”) is added to a mixed solution of an equal amount of triethyl phosphite (hereinafter referred to as “TEP”) and DEC under reflux conditions. And reacted for 2 hours. After the reaction, the reaction solution was dropped into hexane to precipitate phosphonated PES, which was collected by filtration.
The phosphonate was hydrolyzed by heating and refluxing with 10 N hydrochloric acid for 24 hours, washed with distilled water, and dried at 80 ° C. under reduced pressure to obtain a phosphonated PES.

A 5% dimethylformamide (hereinafter referred to as "DMF") solution of phosphonated PES having an equivalent weight of 1000 g / eq and a 5% solution of a sulfonated PES having an equivalent weight of 2000 g / eq obtained in Comparative Example 2 were prepared. DMF
After mixing with a solution at a ratio of 1: 1, the mixture was cast and coated on a glass substrate, dried at 150 ° C. under reduced pressure to remove the solvent, and formed into a film.
A sulfonic acid type polyether sulfone blend membrane was obtained.

Example 3 Polyvinylsulfonate / Sulfonate Type Polyethersulfone Blend Membrane A 5% solution of polyvinylphosphonic acid in DMF used in Example 1 and a 5% solution of sulfonated PES prepared by the method of Comparative Example 2 After mixing with a DMF solution at a ratio of 1: 1, the mixture was cast and coated on a glass substrate, dried at 150 ° C. under reduced pressure to remove the solvent, and formed into a film to form a polyvinyl phosphonic acid / sulfonic acid type polyether. A sulfone blend membrane was obtained.

(Comparative Example 3) Sulfonic acid type polyether ether ketone film Instead of PES, polyether ether ketone (hereinafter, referred to as
A sulfonic acid type PEEK membrane having an equivalent weight of 1900 g / eq was obtained in substantially the same manner as in Comparative Example 2 except that this was referred to as “PEEK”.

Example 4 Phosphonic acid type polyetheretherketone / sulfonic acid type polyetheretherketone blend membrane In substantially the same manner as in Example 2 except that PEEK was used instead of PES, the equivalent weight was 1000 g / eq. Was obtained. 5% D of this phosphonic acid type PEEK
MF solution and 5% of the sulfonic acid type PEEK obtained in Comparative Example 3
% DMF solution at a ratio of 1: 1 and then cast and coated on a glass substrate, dried at 150 ° C. under reduced pressure to remove the solvent and form a film, thereby forming a phosphonic acid type polyether ether ketone / A sulfonic acid type polyether ether ketone blend membrane was obtained.

Example 5 Polyvinylphosphonic acid / sulfonic acid type polyetheretherketone blend membrane 5% DMF solution of polyvinylphosphonic acid used in Example 1 and 5% of sulfonic acid type PEEK obtained in Comparative Example 3 DM
The F solution was mixed at a ratio of 1: 1 and then cast and applied on a glass substrate, dried at 150 ° C. under reduced pressure to remove the solvent, and formed into a film, thereby forming a polyvinyl phosphonic acid / sulfonic acid type polyether. An ether ketone blend membrane was obtained.

The sulfonic acid type polymer membrane obtained by blending the phosphonic acid group-containing polymer components obtained in Examples 2 to 5 and the sulfonic acid type polymer film obtained in Comparative Examples 2 to 3 were prepared. According to the same procedure as in Example 1, an oxidation resistance test was performed. Table 2 shows the results.

[0071]

[Table 2]

The sulfonic acid type polymer membrane containing no phosphonic acid type polymer component (Comparative Examples 2 and 3) was decomposed and made water soluble in an oxidation resistance test for 2 hours. Further, in the case of the sulfonic acid type polymer membrane (Examples 2, 3, 4 and 5) in which the phosphonic acid type polymer component content is 50% and the phosphonic acid type polymer component is blended, the oxidation resistance test 2 The weight retention after the lapse of time was 80 to 95%, indicating higher oxidation resistance as compared with the case of the sulfonic acid type polymer membrane (Comparative Examples 2 and 3).

From the above results, it was revealed that the oxidation resistance of the hydrocarbon-based electrolyte membrane was improved by blending the hydrocarbon-based electrolyte membrane with a component having a phosphonic acid group.

Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention. It is.

For example, in the above embodiment, as the polymer compound having an electrolyte group and a hydrocarbon portion, a graft copolymer having ethylene-tetrafluoroethylene having a sulfonic acid group as a main chain, a polyetheretherketone, or a polyetheretherketone may be used. Although ether sulfone is used, the polymer compound having an electrolyte group and a hydrocarbon portion is not limited thereto, and may be a hydrocarbon-based electrolyte having another electrolyte group such as a carboxylic acid group, or other A high molecular compound having a hydrocarbon portion may be used.

In the above embodiment, polyvinylphosphonic acid, polyethersulfone having a phosphonic acid group introduced, and polyetheretherketone having a phosphonic acid group introduced therein are used as the phosphorus-containing compounds. The compound is not limited thereto, and various compounds having another functional group containing phosphorus, such as a phosphonate ester group or a phosphite group, may be used.

Further, in the above embodiment, the oxidation resistance of the solid polymer electrolyte is improved by uniformly doping the compound having a phosphonic acid group into the hydrocarbon electrolyte having a sulfonic acid group. However, under the conditions of actual use, the most severely oxidative deterioration, for example, a compound having a phosphonic acid group on the surface of a hydrocarbon-based electrolyte having a sulfonic acid group, or a hydrocarbon-based electrolyte having a sulfonic acid group And a film-shaped molded product composed of a mixture of compounds having a phosphonic acid group, may be mechanically bonded to each other by means such as hot pressing, so that the same effect as in the above embodiment can be obtained in actual use. Obtainable.

[0078]

The high-durability solid polymer electrolyte according to the present invention comprises a polymer compound having an electrolyte group and a hydrocarbon moiety,
Since the compound containing phosphorus is mixed, there is an effect that the oxidation resistance of the hydrocarbon portion is improved and a solid polymer electrolyte having high durability can be obtained.

Further, since a polymer compound having a hydrocarbon moiety is relatively inexpensive, a fluorine-containing polymer compound is mixed with a polymer compound having an electrolyte group and a hydrocarbon moiety and a phosphorus-containing polymer compound. There is an effect that a highly durable solid polymer electrolyte having an oxidation resistance equal to or higher than that of an electrolyte or having sufficient oxidation resistance for practical use can be manufactured at low cost.

Therefore, if this is used as an electrolyte membrane for a polymer electrolyte fuel cell, for example, a polymer electrolyte fuel cell having excellent durability can be manufactured at low cost.
This is an invention that is extremely effective in industry.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tomo Morimoto 41-cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture F-term in Toyota Central R & D Laboratories Co., Ltd. 4J002 BC031 BC032 BC111 BC112 BN031 BN032 BQ002 CC031 CC032 CH091 CH092 CN031 CN032 CP211 CP212 GD00 GQ00 5H026 AA06 EE11 EE15 EE17 EE18

Claims (2)

[Claims] 1. A highly durable solid polymer electrolyte obtained by mixing a polymer containing an electrolyte group and a hydrocarbon moiety with a compound containing phosphorus. 2. The highly durable solid electrolyte according to claim 1, wherein the phosphorus-containing compound is a compound having a phosphonic acid group.