JP7068137B2 - Proton conduction membrane and fuel cell - Google Patents

Description

The present disclosure relates to proton conductive membranes and fuel cells.

A proton conductive film is known as an electrolyte material for a fuel cell.

For example, in Patent Document 1,
The first step of dissolving a metal salt of perfluorosulfonic acid and / or a metal salt of perfluorocarboxylic acid in a polymer dispersion containing a polymer electrolyte precursor that exhibits proton conductivity by alkaline hydrolysis and acid treatment.
The second step of forming a polyelectrolyte precursor film from the dispersion obtained in the first step, and
The third step of alkaline hydrolysis and acid treatment of the polyelectrolyte precursor film obtained in the second step to obtain a polyelectrolyte film, and
Perfluorosulfonic acid and / or perfluorocarboxylic acid produced by a method including the fourth step of heating and drying the polymer electrolyte membrane obtained in the third step and precipitating a metal oxide in the polymer electrolyte membrane. A proton conductive film made of an acid-based resin is disclosed.

Japanese Unexamined Patent Publication No. 2010-114020

The presence of water is indispensable for the proton conductive membrane obtained by the technique of Patent Document 1 to exhibit proton conductivity. Therefore, the fuel cell provided with this proton conductive film needs to limit the operating temperature to less than the boiling point of water.

The present disclosure is intended to improve the above circumstances, and an object thereof is to provide a proton conductive film exhibiting high proton conductivity even in an anhydrous environment.

The disclosure that achieves the above objectives is as follows.

<Aspect 1>
Contains crosslinked polymers and plasticizers
The crosslinked polymer has a proton-accepting group of 10 mol% or more of the repeating units constituting the crosslinked polymer.
The plasticizer contains a proton-donating compound having a pKa of 2.5 or less and is a viscoelastic solid in a temperature range of 50 ° C. or higher and 120 ° C. or lower.
Proton conduction membrane.
<Aspect 2>
The proton conduction membrane according to aspect 1, wherein the content of the plasticizer is 60 parts by mass or more and 90 parts by mass or less when the total of the crosslinked polymer and the plasticizer is 100 parts by mass.
<Aspect 3>
The proton conductive membrane according to aspect 1 or 2, wherein the proton-donating compound is one or more selected from sulfuric acid and phosphoric acid.
<Aspect 4>
The proton conduction membrane according to any one of aspects 1 to 3, wherein the proton-accepting group is a nitrogen-containing heterocyclic group.
<Aspect 5>
The proton conduction membrane according to any one of aspects 1 to 4, wherein the glass transition point of the proton conduction membrane is 30 ° C. or lower.
<Aspect 6>
The proton according to any one of aspects 1 to 5, wherein the crosslinked polymer is a copolymer of a first monomer which is a vinyl-based monomer having a proton-accepting group and a second monomer which is a crosslinked vinyl monomer. Conductive membrane.
<Aspect 7>
The proton conduction membrane according to any one of aspects 1 to 6, wherein the proton conductivity of the proton conduction membrane is 7.4 mS / cm or more at 50 ° C.
<Aspect 8>
The proton conduction membrane according to any one of claims 1 to 7, wherein the molar ratio of the proton-donating compound to the proton-accepting group is 1.0 or more and 10.0 or less.
<Aspect 9>
A fuel cell having the proton conductive film according to any one of aspects 1 to 8.
<Aspect 10>
A method for producing a proton conductive film containing a crosslinked polymer and a plasticizer.
The crosslinked polymer has a proton-accepting group of 10 mol% or more of the repeating units constituting the crosslinked polymer.
The plasticizer contains a proton donating compound having a pKa of 2.5 or less.
The proton conductive film is a viscoelastic solid in a temperature range of 50 ° C. or higher and 120 ° C. or lower, and the method is a precursor polymer obtained by polymerizing a first monomer which is a vinyl-based monomer having a proton-accepting group. And by adding a cross-linking agent to the precursor polymer to cross-link the precursor polymer, the present invention comprises obtaining the cross-linked polymer.
A method for manufacturing a proton conductive membrane.
<Aspect 11>
A method for producing a proton conductive film containing a crosslinked polymer and a plasticizer.
The crosslinked polymer has a proton-accepting group of 10 mol% or more of the repeating units constituting the crosslinked polymer.
The plasticizer contains a proton donating compound having a pKa of 2.5 or less.
The proton conductive film is a viscous elastic solid in a temperature range of 50 ° C. or higher and 120 ° C. or lower, and the method is a first monomer which is a vinyl-based monomer having a proton-accepting group and a crosslinkable vinyl monomer. The cross-linking polymer is obtained by polymerizing and cross-linking with the second monomer.
A method for manufacturing a proton conductive membrane.

The proton conductive membrane of the present disclosure can exhibit high proton conductivity even in an anhydrous environment. Therefore, the proton conduction membrane of the present disclosure is particularly suitable for use as a proton conduction membrane in a fuel cell.

FIG. 1 is a schematic diagram for explaining the mechanism by which the proton conductive membrane of the present disclosure expresses its function. FIG. 2 is a diagram showing a stress-strain curve obtained from the tensile test of Example 9. FIG. 3 is a diagram showing the change tendency of the glass transition point of the polymer of Reference Example 1 when the molar ratio of the proton-donating compound to the proton-accepting group changes. FIG. 4 is a diagram showing the change tendency of the proton conductivity when the molar ratio of the proton-donating compound to the proton-accepting group changes in the polymer of Reference Example 2.

The proton conductive membrane of the present disclosure is
Contains crosslinked polymers and plasticizers
The crosslinked polymer has a proton-accepting group of 10 mol% or more of the repeating units constituting the crosslinked polymer.
The plasticizer contains a proton-donating compound having a pKa of 2.5 or less and is a viscoelastic solid in a temperature range of 50 ° C. or higher and 120 ° C. or lower.

With respect to the present disclosure, "viscoelastic solid" means a solid that is viscous and elastic, does not exhibit fluidity, and maintains its shape. Specifically, in this "viscoelastic solid" substance, when stress is applied to cause a small deformation, the stress on the deformation becomes maximum immediately after the deformation and decreases with the passage of time. Finally, it becomes a constant value other than 0, and when the stress deformed in that state is removed, the deformation becomes small, and in some cases, it has the property of returning to the original shape.

The proton conductive membrane of the present disclosure can exhibit high proton conductivity even in an anhydrous environment. It is believed that the high proton conductivity of the proton conductive membranes of the present disclosure is obtained by the transfer of protons provided by the proton donor compound as a plasticizer over the proton accepting groups of the crosslinked polymer.

Further, in the proton conductive film of the present disclosure, a proton donating compound as a plasticizer donates a proton to anionize it, and a proton accepting group of a crosslinked polymer receives a proton to cationize between them. It is considered that the proton donating compound as a plasticizer stays in the crosslinked polymer due to the electrostatic interaction of the above, thereby maintaining the state of the viscoelastic solid as a whole. It is considered that such a viscoelastic solid promotes molecular motion in the proton conductive membrane, thereby promoting proton conductivity.

On the other hand, it is considered that the proton conductive film of the present disclosure maintains the film shape because the crosslinked structure of the polymer contributes. That is, it is considered that the crosslinked polymer maintains the film shape due to its crosslinked structure.

To maintain the membrane shape of the proton conductive film, for example, the proton conductive film is placed in the operating temperature range of the battery (for example, in the range of 50 ° C. or higher and 120 ° C. or lower, particularly in the range of 40 ° C. or higher and 200 ° C. or lower, or 0 ° C. or higher and 150 ° C. In the following range), the proton conductive membrane does not substantially deform and contract when left to stand for 1 hour under no load, for example, the rate of change in length in the plane direction and the thickness direction of the proton conductive film. For example, it means that it is 5% or less, 3% or less, or 1% or less.

FIG. 1 shows a schematic diagram for explaining the mechanism by which the proton conductive membrane of the present disclosure expresses its function.

The proton conductive membrane of FIG. 1 is composed of a "crosslinked polymer" having a "proton-accepting group" and a "plasticizer" which is a proton-donating compound. The "crosslinked polymer" is crosslinked at the "crosslink point" to form a crosslinked structure. Thereby, the proton conductive film of the present disclosure can maintain the film shape. The "plasticizer" in FIG. 1 is depicted as a proton donating dibasic acid.

The proton donating group of the "plasticizer" releases one or two protons to form a "monovalent anion" or "divalent anion". On the other hand, the released protons are accepted by the "proton-accepting group" of the "crosslinked polymer" to form a "cation". In this state, in the proton conduction membrane of FIG. 1, which is a viscoelastic solid, the plasticizer can exhibit high molecular mobility, so that the protons can easily move in the membrane, whereby the high protons can be obtained. Shows electric power.

Further, the "monovalent anion" or "divalent anion" after the "plastic agent" releases the proton and the "cation" after the "proton-accepting group" of the "crosslinked polymer" receives the proton are By forming an "ionic interaction", the "plastic agent" is retained in the membrane and highly suppressed from leaking out of the membrane, and the membrane remains in a viscoelastic solid state as a whole. can do.

Hereinafter, the proton conductive membrane of the present disclosure will be described with reference to a preferred embodiment as an example.

<Crosslink polymer>
The crosslinked polymer contained in the proton conductive membrane of the present disclosure has a proton-accepting group of 10 mol% or more of the repeating units constituting the crosslinked polymer.

The proton-accepting group of the crosslinked polymer may be a nitrogen-containing heterocyclic group. The nitrogen-containing heterocyclic group may be, for example, a pyridine ring group, an imidazole ring group, a pyrazole ring group, an imidazoline ring group, an oxazole ring group, a pyrimidine ring group, a pyrazine ring group, a triazole ring group, a tetrazole ring group or the like. These nitrogen-containing heterocyclic groups are preferably nitrogen-containing heteroaromatic ring groups, and particularly preferably pyridine ring groups or imidazole ring groups.

Thus, for example, the crosslinked polymers are poly (2-vinylpyridine), poly (4-vinylpyridine), poly (1-vinylimidazole), poly (2-methyl-1-vinylimidazole), poly (2-vinylimidazole). ), Poly (4-vinylimidazole), poly (2-phenyl-1-vinylimidazole), poly (1-vinylcarbazole), or poly ((meth) acrylate 2- (1H-imidazole-1-yl) ethyl) ) Etc., but is not limited to these.

The presence of 10 mol% or more of the repeating unit of the crosslinked polymer in the crosslinked polymer ensures sufficiently high proton conductivity and suppresses leakage of the plasticizer by ionic interaction. Is preferable.

This ratio is 15 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, 95 mol% or more, 96 mol% or more, or 97 mol. It may be% or more. The ratio is 99.5 mol% or less, 99 mol% or less, 98 mol% or less, 95 mol% or less, 90 mol% or less, 80 mol% or less, 70 mol% or less, 60 mol% or less, 50 mol% or less, 40 mol% or less, or 35 mol. It may be less than or equal to%.

The amount (number of moles) of proton-accepting groups per 1 g of the crosslinked polymer is, for example, 0.1 mmol / g-polymer or more, 0.5 mmol / g-polymer or more, 1.0 mmol / g-polymer or more, 2.5 mmol /. It may be g-polymer or more, or 5.0 mmol / g-polymer or more, and from the viewpoint of facilitating the synthesis of the crosslinked polymer and ensuring the handleability of the obtained polymer, for example, 50 mmol / g-polymer or less. It may be 40 mmol / g-polymer or less, 30 mmol / g-polymer or less, or 25 mmol / g-polymer or less.

The crosslinked polymer, in combination with a plasticizer described below, forms a viscoelastic solid proton conductive film, thereby providing high molecular mobility. Therefore, the glass transition point Tg of the crosslinked polymer alone may be relatively high. However, if the glass transition point of the crosslinked polymer is excessively high, the molecular mobility may not be sufficiently improved even after being mixed with the plasticizer.

Therefore, the glass transition point of the crosslinked polymer may be 400 ° C. or lower, 350 ° C. or lower, 300 ° C. or lower, or 250 ° C. or lower. The crosslinked polymer may have two or more glass transition points. When the crosslinked polymer has two or more glass transition points, the lowest glass transition point is below the operating temperature of the proton conductive membrane (eg, 50 ° C. or higher, 150 ° C. or lower, preferably 120 ° C. or lower) or lower. The temperature is preferably 30 ° C. or lower, 20 ° C. or lower, 10 ° C. or lower, or 0 ° C. or lower. The cross-linked polymer having such a low glass transition point allows the cross-linked polymer to maintain high molecular mobility with the plasticizer during operation of the resulting proton conductive membrane, thus obtaining high proton conductivity. Can be done.

The structure of the repeating unit of the crosslinked polymer may be arbitrary. For example, the repeating unit of the crosslinked polymer may be derived from a vinyl-based monomer, an ether-based monomer, an ester-based monomer, an amide-based monomer, a silicone-based monomer, or the like. A method for producing each polymer and a method for forming a crosslinked structure are known. Of the above, the repeating unit of the crosslinked polymer is preferably derived from a vinyl-based monomer because the monomer is easily available and molecular modification is easy.

The crosslinked polymer in the present disclosure is preferably a copolymer of a first monomer which is a monomer having a proton-accepting group and a second monomer which is crosslinked. The crosslinked polymer in the present disclosure may be a copolymer further having a third monomer in combination with the first monomer and the second monomer, if desired. In the following, examples of these first, second, and third polymers will be given.

(1st monomer)
The first monomer is a monomer having a proton-accepting group, and may be, for example, a monomer having one or more proton-accepting groups and one or more polymerizable groups, particularly one proton-accepting group and one. It may be a monomer having a polymerizable group. Further, at least a part of hydrogen in the monomer molecule may be replaced with fluorine. The preferred first monomer in the present disclosure is a vinyl-based monomer, and examples thereof for each type of proton-accepting group are as follows.

Vinyl monomer having a pyridine ring: 2-vinylpyridine, 4-vinylpyridine, etc.

Vinyl monomer with imidazole ring: 1-vinyl imidazole, 2-methyl-1-vinyl imidazole, 2-vinyl imidazole, 4-vinyl imidazole, 2-phenyl-1-vinyl imidazole, 1-vinyl carbazole, (meth) acrylic acid 2- (1H-imidazole-1-yl) ethyl and the like.

Vinyl monomer having a pyrazole ring: 1-vinylpyrazole, 3-vinylpyrazole, etc.

Vinyl monomer having an imidazoline ring: 1-vinyl-2-imidazoline, 1-vinyl-2-methylimidazoline, 2-vinyl-2-imidazoline, 2- (1H-imidazolin-1-yl) ethyl (meth) acrylate, etc. ..

Vinyl monomer having an oxazole ring: 2-phenyl-5-vinyloxazole and the like.

Vinyl monomer having a pyrimidine ring: 5-vinylpyrimidine, 2,4-dichloro-6-vinylpyrimidine and the like.

Vinyl monomer having a pyrazine ring: 2-vinylpyrazine, 2,5-dimethyl-3-vinylpyrazine, 2-methyl-5-vinylpyrazine and the like.

Vinyl monomer having a triazole ring: 2,4-diamino-6-vinyltriazine and the like.

Vinyl monomer having a tetrazole ring: 1-vinyl-1H-tetrazole, 2-vinyl-2H-tetrazole, 5-vinyl-1H-tetrazole, 1-methyl-5-vinyl-1H-tetrazole and the like.

The first monomer is particularly preferably 4-vinylpyridine or 1-vinylimidazole.

In addition, in this specification, "(meth) acrylic acid" is a concept including both acrylic acid and methacrylic acid. "(Meta) acrylate", "(meth) acrylamide", etc. should be understood accordingly.

(Second monomer)
The second monomer is a crosslinkable monomer, for example, a monomer having two or more polymerizable groups, and in particular, a monomer having two polymerizable groups. Further, at least a part of hydrogen in the monomer molecule may be replaced with fluorine. The preferred second monomer in the present disclosure is a vinyl-based monomer, for example, N, N'-methylenebis (meth) acrylamide, divinylbenzene, vinyl (meth) acrylate, allyl (meth) acrylate, 1,6-hexadiene. And so on.

(Third monomer)
The third monomer is a monomer other than the first monomer and the second monomer, and may be, for example, a non-crosslinkable monomer having one polymerizable group and no proton accepting group. Further, at least a part of hydrogen in the monomer molecule may be replaced with fluorine. The preferred third monomer in the present disclosure is a vinyl-based monomer, and may be, for example, (meth) acrylic acid ester, styrene and its derivative, conjugated diene, or the like, and specifically, for example, methyl (meth) acrylate. It may be ethyl (meth) acrylate, -2- (2-ethoxyethoxy) ethyl (meth) acrylate, styrene, α-methylstyrene, butadiene, isoprene and the like.

(Copolymerization ratio of each monomer)
The copolymerization ratio of each monomer in the crosslinked polymer of the present disclosure is arbitrary.

When the total of the monomers constituting the crosslinked polymer is 100 parts by mass, the ratio of the first monomer is, for example, 5.0 parts by mass or more, 7.5 parts by mass or more, 10 parts by mass or more, 15 parts by mass or more, 20. 7 parts by mass or more, 25 parts by mass or more, 30 parts by mass or more, 35 parts by mass or more, 40 parts by mass or more, 45 parts by mass or more, 50 parts by mass or more, 55 parts by mass or more, 60 parts by mass or more, 65 parts by mass or more, 70 It may be 7 parts by mass or more, 75 parts by mass or more, 80 parts by mass or more, 85 parts by mass or more, 90 parts by mass or more, 95 parts by mass or more, 97 parts by mass or more, 99 parts by mass or more, or 100 parts by mass.

Further, from the viewpoint of achieving both excellent proton conductivity, film shape retention and good handleability when the degree of cross-linking is appropriately set and used as a proton conductive film, the first monomer and the second monomer are used. When the total is 100 parts by mass, the amount of the second monomer is, for example, 0.1 part by mass or more, 0.5 part by mass or more, 1.0 part by mass or more, 1.5 parts by mass or more, and 2.0 parts by mass. It may be 5 parts or more or 2.5 parts by mass or more, for example, 5.0 parts by mass or less, 4.5 parts by mass or less, 4.0 parts by mass or less, 3.5 parts by mass or less, 3.0 parts by mass. Hereinafter, it may be 2.5 parts by mass or less. A cross-linking agent or the like can be appropriately added in place of the second monomer or in addition to the second monomer to form a cross-link. The ratio of the cross-linking agent when the cross-linking agent is used instead of the second monomer and the total ratio when the second monomer and the cross-linking agent are used in combination are not particularly limited, and the second monomer listed above is not particularly limited. May be the same as the amount of.

Further, from the viewpoint of ensuring excellent proton conductivity and film shape retention, the amount of the third monomer when the total of the first monomer, the second monomer, and the third monomer is 100 parts by mass is, for example, It may be 50 parts by mass or less, 40 parts by mass or less, 30 parts by mass or less, 20 parts by mass or less, 15 parts by mass or less, 10 parts by mass or less, 5 parts by mass or less, or 1 part by mass or less. It is not necessary to use the third monomer.

In this disclosure, "parts by mass" and "% by mass" are merely differences in expression and are treated as synonymous unless otherwise specified. For example, "when the total is 100 parts by mass, the amount of component X is x parts by mass" and "when the total is 100% by mass, the amount of component X is x% by mass". Is synonymous with.

(Copolymerization method)
The copolymer of the first to third monomers can be obtained by a known polymerization method, for example, a radical polymerization method, a cationic polymerization method, an anion polymerization method, or the like, and a radical polymerization method is preferable.

The radical polymerization may be carried out by contacting a predetermined monomer mixture with a radical polymerization initiator. Radical polymerization may be carried out in the presence of a plasticizer described below.

The radical polymerization initiator may be selected from, for example, an azo compound, hydrogen peroxide, an organic peroxide and the like. The azo compound is selected from, for example, azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) and the like. May be done. The organic peroxide may be selected from, for example, benzoyl peroxide, diisobutyl peroxide and the like.

The ratio of the radical polymerization initiator used is, for example, 0.001 part by mass or more, 0.003 part by mass or more, 0.005 part by mass or more, 0.01 part by mass or more, or more than 100 parts by mass of the total amount of the monomer. It may be 0.05 parts by mass or more, for example, 3.0 parts by mass or less, 2.0 parts by mass or less, 1.0 part by mass or less, 0.5 parts by mass or less, or 0.1 parts by mass or less. You may.

The radical polymerization may be carried out in the absence of a solvent or optionally in a suitable solvent.

The radical polymerization is carried out, for example, at a temperature of 40 ° C. or higher, 50 ° C. or higher, 60 ° C. or higher, or 70 ° C. or higher, for example, 200 ° C. or lower, 150 ° C. or lower, 120 ° C. or lower, or 100 ° C. or lower, for example, 30 minutes or longer. It can be carried out for 1 hour or more, 2 hours or more, or 3 hours or more, for example, 10 hours or less, 8 hours or less, 5 hours or less, or 3 hours or less.

After the polymerization, in order to remove unreacted monomers, small molecule oligomers, radical initiator residues and the like, the obtained polymer may be purified by an appropriate method. The purification method may be, for example, a method such as solvent substitution or reprecipitation.

<Plasticizer>
The plasticizer contained in the proton conductive film of the present disclosure is pKa2.5 or less, pKa2.3 or less, pKa2.1 or less, pKa2.0 or less, pKa1.0 or less, pKa0.0 or less, pKa-1.0 or less, Alternatively, it contains a proton donating compound having a pKa-2.0 or less. Therefore, this plasticizer comprises a proton donating compound having a high acidity, that is, a compound having a high tendency to release a proton. When the proton donating compound is a polybasic acid, this pKa means pKa ₁ .

The proton donating compound may be a compound having one or more groups selected from a sulfonic acid group and a phosphoric acid group. The pKa of the sulfonic acid group is about −3.0, and the PKa (pKa ₁ ) of the phosphoric acid group is about 2.1.

The proton-donating compound preferably has a high boiling point or decomposition temperature that does not cause volatile evaporation or decomposition at the operating temperature of the proton conductive film. From this point of view, the boiling point or decomposition temperature of the proton donating compound may be, for example, more than 120 ° C., 150 ° C. or higher, or 200 ° C. or higher.

The proton donating compound may be one or more selected from sulfuric acid and phosphoric acid, and may be sulfuric acid or phosphoric acid. The boiling point of sulfuric acid is about 290 ° C (decomposition), and the boiling point of phosphoric acid is about 213 ° C (decomposition).

The plasticizer may be composed of only the proton-donating compound, or may be composed of the proton-donating compound and other plasticizers. The other plasticizer may be a plasticizer having no proton donating property, and specifically, for example, polyalkylene glycol, polyvinyl ether, polyol ester and the like may be used. The ratio of other plasticizers used is, for example, 50 parts by mass or less, 30 parts by mass or less, 10 parts by mass or less, 5 parts by mass or less, or 1 part by mass or less when the total mass of the plasticizer is 100 parts by mass. And it is not necessary to use any other plasticizer.

In addition, in this specification, an "alkylene group" is a concept including a methylene group, an alkylmethylene group, and a dialkylmethylene group.

(Mole ratio of proton donating compound to proton accepting group)
The molar ratio of the proton-donating compound to the proton-accepting group (proton-donating compound / proton-accepting group) is not particularly limited, and from the viewpoint of ensuring the function of the proton-donating compound as a plasticizer, for example, 1.0. 1.1 or more, 1.3 or more, 1.4 or more, 1.5 or more, 1.6 or more, 1.7 or more, 1.8 or more, 1.9 or more, 2.0 or more, 2.1 2.2 or more, 2.3 or more, 2.4 or more, 2.5 or more, 2.6 or more, 2.7 or more, 2.8 or more, 2.9 or more, 3.0 or more, 3.1 3.4 or more, 3.5 or more, 3.6 or more, 3.7 or more, 3.8 or more, 3.9 or more, 4.0 or more, 4.1 or more, 4.2 or more, or 4. It may be 3 or more. Further, the upper limit of this molar ratio is not particularly limited, and from the viewpoint of maintaining the film strength and ensuring the stability as a film, for example, 10.0 or less, 9.0 or less, 8.5 or less, 8.0 or less. Below, 7.5 or less, 7.0 or less, 6.5 or less, 6.0 or less, 5.5 or less, 5.0 or less, 4.5 or less, 4.4 or less, or 4.3 or less. good.

<Ratio of crosslinked polymer and plasticizer>
The ratio of the crosslinked polymer to the plasticizer is the ratio of the crosslinked polymer and the plasticizer to 100 parts by mass in total from the viewpoint of enhancing the molecular motility of the obtained proton conductive film and obtaining sufficiently high proton conductivity. It may be 60 parts by mass or more, 65 parts by mass or more, 70 parts by mass or more, 75 parts by mass or more, or 80 parts by mass or more. On the other hand, from the viewpoint of maintaining the film strength and ensuring the stability as a film, the ratio of the plasticizer used to the total 100 parts by mass of the crosslinked polymer and the plasticizer is 90 parts by mass or less, 85 parts by mass or less, and 82 parts by mass. It may be 10 parts or less, 80 parts by mass or less, 75 parts by mass or less, 70 parts by mass or less, or 65 parts by mass or less.

<Glass transition point of proton conductive film, proton conductivity, and water content>
(Glass transition point)
The proton conductive membrane of the present disclosure exhibits high molecular mobility as a whole of the membrane by containing a crosslinked polymer and a plasticizer. The high molecular motion of the proton conductive film can be evaluated by the low glass transition point Tg.

The proton conductive film of the present disclosure can maintain the molecular motion even at a low temperature due to the high molecular motion of the introduced plasticizer itself and the low glass transition point Tg as the film. Therefore, high proton conductivity can be obtained. The glass transition point Tg of the proton conductive film is preferably not more than the lower limit of the operating temperature of the proton conduction film, for example, 0 ° C. or less, -20 ° C. or less, -40 ° C. or less, -60 ° C. or less, or -65. It may be below ° C.

The glass transition point Tg in the present specification is a value obtained in accordance with JIS K 7121 based on the DSC curve obtained by measuring at a heating rate of 10 ° C./min.

(Proton conductivity)
The proton conductive membrane of the present disclosure exhibits high proton conductivity. The proton conductivity of the proton conductive membrane of the present disclosure may be 7.4 mS / cm or more at 50 ° C. This value may be, for example, 10 mS / cm or more, 15 mS / cm or more, 30 mS / cm or more, 50 mS / cm or more, 75 mS / cm or more, 100 mS / cm or more, or 120 mS / cm or more. Further, the proton conductivity of the proton conductive film of the present disclosure is, for example, 19 mS / cm or more, 20 mS / cm or more, 30 mS / cm or more, 50 mS / cm or more, 75 mS / cm or more, 100 mS / cm or more at 120 ° C. It may be 125 mS / cm or more, 150 mS / cm or more, 175 mS / cm or more, 200 mS / cm or more, or 210 mS / cm or more.

(Water content)
The proton conductive membrane of the present disclosure exhibits high proton conductivity even when the membrane does not contain water. Therefore, the water content of the proton conductive membrane is, for example, 1 part by mass or less, 0.1 part by mass or less, 0.01 part by mass or less, or 0.001 part by mass when the total mass of the membrane is 100 parts by mass. It may be less than or equal to a part.

<Manufacturing method of proton conductive film>
The present disclosure also provides a first production method and a second production method as a method for producing a proton conductive film containing the above-mentioned crosslinked polymer and plasticizer. Any method can be used to produce the proton conductive film of the present disclosure. Hereinafter, each manufacturing method will be described. In each manufacturing method, the description of duplication will be omitted for the parts that can be shared with the above-mentioned "proton conduction membrane".

(First manufacturing method)
The first manufacturing method of the present disclosure is
A method for producing a proton conductive film containing a crosslinked polymer and a plasticizer.
The crosslinked polymer has a proton-accepting group of 10 mol% or more of the repeating units constituting the crosslinked polymer.
The plasticizer contains a proton donating compound with a pKa of 2.5 or less.
The proton conductive film is a viscoelastic solid in a temperature range of 50 ° C. or higher and 120 ° C. or lower, and the first production method is to polymerize a first monomer, which is a vinyl-based monomer having a proton-accepting group, to form a precursor. It involves obtaining a crosslinked polymer by obtaining a polymer and then adding a crosslinking agent to the precursor polymer to crosslink the precursor polymer.

Here, the method for polymerizing the first monomer is not particularly limited, and may be, for example, radical polymerization using a RAFT agent (reversible non-cleavable chain transfer agent). The details of the radical polymerization conditions, the radical polymerization initiator, and the first monomer are as described above, and the description thereof will be omitted here.

Examples of the RAFT agent include thiocarbonylthio compounds such as dithioester, dithiocarbamate, trithiocarbonate, and xantate. Specific examples of the RAFT agent include bis (n-octylmercapto-thiocarbonyl) disulfide, 4-cyano-4-[(dodecylsulfanylthiocarbonyl) sulfanyl] pentanoic acid, and 2- (dodecylthiocarbonothio oilthio)-. 2-Methylpropionic acid, S, S'-bis (α, α'-dimethyl-α''-acetic acid) trithiocarbonate, 2-cyano-2-propyldodecyltrithiocarbonate, 4-cyano-4- (phenyl) Carbonothio oil thio) Pentanoic acid, cyanomethyldodecyltrithiocarbonate, 2-cyano-2-propylbenzodithionate and the like, but are not limited thereto.

The amount of the RAFT agent used is, for example, 0.001 mol or more, 0.005 mol or more, 0.010 mol or more, 0.015 mol or more, 0.020 mol or more, 0.025 with respect to 100 mol of the first monomer. More than mol, 0.030 mol or more, 0.035 mol or more, 0.040 mol or more, 0.045 mol or more, 0.050 mol or more, 0.055 mol or more, 0.060 mol or more, 0.065 mol or more , 0.070 mol or more, 0.075 mol or more, 0.080 mol or more, 0.085 mol or more, 0.090 mol or more, or 0.095 mol or more, and 0.50 mol or less, 0 It may be .40 mol or less, 0.30 mol or less, 0.20 mol or less, 0.10 mol or less, or 0.095 mol or less.

Then, a cross-linked polymer can be obtained by adding a cross-linking agent to the precursor polymer obtained by polymerizing the first monomer and cross-linking the precursor polymer.

Here, the cross-linking agent is not particularly limited, and for example, 1,2-dichloroethane, 1,2-dibromoethane, 1,3-dichloropropane, 1,3-dibromopropane, 1,4-dichlorobutane, 1, Examples thereof include, but are not limited to, dihalogenated hydrocarbons such as 4-dibromobutane, 1,4-dichloro-2-butene, and 3,4-dichloro-1-butene.

When cross-linking the precursor polymer, a solvent may be added as appropriate. From the viewpoint of simplifying the post-treatment, it is preferable to add an evaporative solvent such as methanol or ethanol.

The temperature at the time of crosslinking is not particularly limited, and may be room temperature or may be appropriately heated. The cross-linking time is not particularly limited and may be from several minutes to several days. Further, when an evaporative solvent is used, the crosslinking reaction can be allowed to proceed while evaporating the solvent.

(Second manufacturing method)
The second manufacturing method of the present disclosure is
A method for producing a proton conductive film containing a crosslinked polymer and a plasticizer.
The crosslinked polymer has a proton-accepting group of 10 mol% or more of the repeating units constituting the crosslinked polymer.
The plasticizer contains a proton donating compound with a pKa of 2.5 or less.
The proton conductive film is a viscous elastic solid in a temperature range of 50 ° C. or higher and 120 ° C. or lower, and the second production method is a first monomer which is a vinyl-based monomer having a proton-accepting group and a crosslinkable vinyl monomer. It involves obtaining a crosslinked polymer by polymerizing and crosslinking with a second monomer.

Here, as a method for polymerizing and cross-linking the first monomer and the second monomer, the above-mentioned "copolymerization method" can be appropriately adopted. Further, if necessary, the above-mentioned third monomer may be used.

The proton conductive film of the present disclosure can be produced, for example, by introducing a plasticizer into the crosslinked polymer obtained by the first production method or the second production method described above. The introduction of the plasticizer into the crosslinked polymer can be done in a volatile solvent.

The solvent used here may be selected from a polar solvent having a high affinity with the crosslinked polymer and the plasticizer and stable to a strong acid, and specifically, for example, alcohol, ether or the like may be used. The alcohol may be, for example, methanol, ethanol or the like. The ether may be, for example, dimethyl ether, diethyl ether, tetrahydrofuran or the like. The amount of the solvent used is, for example, 500 parts by mass or more, 750 parts by mass or more, 1,000 parts by mass or more, 1,250 parts by mass or more, or 1,500 parts by mass with respect to a total of 100 parts by mass of the crosslinked polymer and the plasticizer. It may be 5 parts by mass or more, and may be, for example, 5,000 parts by mass or less, 4,500 parts by mass or less, 4,000 parts by mass or less, 3,500 parts by mass or less, or 3,000 parts by mass or less.

The crosslinked polymer is immersed in a solution in which a plasticizer is dissolved in a solvent, and then the solvent is removed to obtain the proton conductive film of the present disclosure.

The proton conductive film can be appropriately formed into a film shape by, for example, a casting method, a pressing method, or the like, after the plasticizer is introduced into the crosslinked polymer and before the solvent is removed.

<Fuel cell>
The fuel cell of the present disclosure has the proton conductive film of the present disclosure. In particular, in the fuel cell of the present disclosure, the fuel pole side separator having a fuel flow path, the fuel pole side catalyst layer, the proton conduction film of the present disclosure, the air pole side catalyst layer, and the air pole side separator having an air flow path are in this order. It has a laminated body laminated with. Further, in particular, the fuel cell of the present disclosure includes a fuel electrode side separator having a fuel flow path, a fuel electrode side gas diffusion layer, a fuel electrode side catalyst layer, a proton conduction film of the present disclosure, an air electrode side catalyst layer, and an air electrode side gas diffusion. It has a laminated body in which a layer and an air electrode side separator having an air flow path are laminated in this order.

Hereinafter, the present disclosure will be described in detail in the form of examples. The following examples do not limit the use of the present disclosure in any way.

《Polymer synthesis》
<Synthesis Example 1: Synthesis of crosslinked P4VP>
In this synthesis example, a crosslinked polymer having a pyridyl group as a proton-accepting group as a repeating unit was synthesized as follows.

A column packed with basic alumina was purified through unpurified 4-vinylpyridine.

Purified 4-vinylpyridine (4VP) 2.00 g (19.0 mmol) as the first monomer having a proton-accepting group, N, N'-methylenebisacrylamide (MBAA) 50 as the crosslinkable second monomer .3 mg (0.326 mmol) and 2.0 mg (0.012 mmol) of azobisisobutyronitrile (AIBN) as a radical polymerization initiator were mixed in a sample bottle to obtain a raw material solution. The mass ratio of the first monomer: the second monomer: the radical polymerization initiator in this raw material liquid was about 1000: 25: 1. Moreover, the molar ratio of the first monomer: the second monomer: the radical polymerization initiator in this raw material liquid was about 1583: 27: 1. If the polymerization proceeds according to the mixing ratio of the monomers, the proportion of the first monomer having a pyridyl group as a proton-accepting group in the repeating units of the obtained crosslinked polymer is about 97.6% by mass (≈1000 /). (1000 + 25)) should be. These values are summarized in Table 1 below.

After bubbling the raw material liquid with nitrogen gas for 45 minutes, the temperature was raised to 70 ° C. under normal pressure with an oil bath, and the polymerization reaction was carried out under stirring at 500 rpm for 3.5 hours. After completion of the reaction, the sample bottle was removed from the oil bath and allowed to stand on a hot plate at 50 ° C. for 2 days. After 2 days, it was confirmed that the sample in the sample bottle was glassy.

40 mL of methanol was added to the sample in the sample bottle, and the sample was immersed for 1 hour. After 1 hour, the methanol was removed, the same amount of fresh methanol was added, and the immersion was performed again for 1 hour. This methanol immersion operation was repeated 3 times to remove unreacted monomers, small molecule oligomers and the like for purification. Then, after allowing to stand on a hot plate at 50 ° C. for 1 day, the cross-linked poly (4-vinylpyridine) (cross-linked P4VP) was dried in a vacuum dryer at 50 ° C. for 12 hours to completely remove methanol. ) Was obtained.

The structure of the obtained crosslinked P4VP is shown below.

<Synthesis Example 2 (Comparative Synthesis Example): Synthesis of non-crosslinked P4VP>
In this synthesis example, a non-crosslinked polymer having a pyridyl group as a proton-accepting group as a repeating unit was synthesized as follows.

A column packed with basic alumina was purified through unpurified 4-vinylpyridine.

40 mL (376 mmol) of 4-vinylpyridine (4VP) as the first monomer having a proton-accepting radical, S, S'-bis (α, α'-dimethyl- as a reversible addition cleavage chain transfer agent (RAFT agent) 101 mg (0.358 mmol) of α''-acetic acid) trithiocarbonate and 29.4 mg (0.179 mmol) of azobisisobutyronitrile (AIBN) as a radical polymerization initiator are mixed in a eggplant flask to prepare a raw material. Obtained liquid. The molar ratio of the first monomer: RAFT agent: radical polymerization initiator in this raw material liquid was approximately 2100: 2: 1. If the polymerization proceeds according to the mixing ratio of the monomers, the proportion of the first monomer having a pyridyl group as a proton-accepting group in the repeating units of the obtained non-crosslinked polymer should be about 100% by mass. ..

After bubbling the raw material liquid with nitrogen gas for 45 minutes, the temperature was raised to 80 ° C. under normal pressure under normal pressure, and the polymerization reaction was carried out under stirring at 500 rpm for 1.5 hours. After completion of the reaction, the eggplant flask was immersed in liquid nitrogen to terminate the polymerization.

Using the sample in the eggplant flask after the polymerization was stopped, the average degree of polymerization of the non-crosslinked 4VP was examined. Specifically, a part of the sample in the eggplant flask was dissolved in deuterated chloroform and ¹ H-NMR was measured to estimate the conversion rate of the non-crosslinked 4VP, and the average degree of polymerization was determined. As a result, the conversion rate of the non-crosslinked 4VP was 38%, and the average degree of polymerization was 399.

The sample in the eggplant flask after the polymerization was stopped was reprecipitated and purified. Specifically, reprecipitation purification was performed as follows.

Chloroform was added to the sample to prepare a polymer solution having a concentration of 8% by mass. This polymer solution was added dropwise into a large excess of n-hexane to precipitate solid non-crosslinked poly (4-vinylpyridine) (non-crosslinked P4VP). The obtained solid polymer was suction-filtered and separated, and then sufficiently dried by vacuum drying. The dried non-crosslinked P4VP was dissolved in chloroform again and dropped into n-hexane to precipitate a solid uncrosslinked P4VP. The precipitation operation of non-crosslinked P4VP was carried out a total of 3 times to remove unreacted monomers, small molecule oligomers and the like. Then, it was sufficiently dried by vacuum drying to obtain a purified non-crosslinked P4VP.

For the obtained purified non-crosslinked P4VP, the molecular weight distribution (Mw / Mn) measured by gel permeation chromatography (GPC) under the following conditions was 1.3.
Solvent, eluent: N, N-dimethylformamide (DMF)
Polymer concentration: 0.5% by mass
Eluent flow rate: 1 mL / min Column: Tosoh Corporation, 3 "TSK-GEL column 4000HR" connected

The structure of the obtained non-crosslinked P4VP is shown below.

<Synthesis Example 3: Synthesis of crosslinked PVIm>
In this synthesis example, a crosslinked polymer having an imidazolyl group as a repeating unit as a proton-accepting group was synthesized as follows.

A column packed with basic alumina was purified by passing unpurified 1-vinylimidazole.

2.01 g (21.4 mmol) of 1-vinylimidazole (VIm) after purification as a first monomer having a proton-accepting group, N, N'-methylenebisacrylamide (MBAA) 50 as a crosslinkable second monomer .1 mg (0.325 mmol) and 2.3 mg (0.014 mmol) of azobisisobutyronitrile (AIBN) as a radical polymerization initiator were mixed in a sample bottle to obtain a raw material solution. The mass ratio of the first monomer: the second monomer: the radical polymerization initiator in this raw material liquid was about 1000: 25: 1. Moreover, the molar ratio of the first monomer: the second monomer: the radical polymerization initiator in this raw material liquid was about 1528: 23: 1. If the polymerization proceeds according to the mixing ratio of the monomers, the proportion of the first monomer having an imidazolyl group as a proton-accepting group in the repeating units of the obtained crosslinked polymer is about 97.6% by mass (≈1000 /). (1000 + 25)) should be. These values are summarized in Table 1 below.

After bubbling the raw material liquid with nitrogen gas for 40 minutes, the temperature was raised to 80 ° C. under normal pressure with an oil bath, and the polymerization reaction was carried out for 4 hours under stirring at 500 rpm. After completion of the reaction, the sample bottle was removed from the oil bath and allowed to stand on a hot plate at 50 ° C. for 2 days. After 2 days, it was confirmed that the sample in the sample bottle was glassy.

40 mL of methanol was added to the sample in the sample bottle, and the sample was immersed for 1 hour. After 1 hour, the methanol was removed, the same amount of fresh methanol was added, and the immersion was performed again for 1 hour. This methanol immersion operation was repeated 3 times to remove unreacted monomers, small molecule oligomers and the like for purification. The crosslinked poly (1-vinylimidazole) (crosslinked) was then allowed to stand on a hot plate at 50 ° C. for 1 day and then dried in a vacuum dryer at 50 ° C. for 2 days to completely remove methanol. PVIm) was obtained.

The structure of the obtained crosslinked PVIm is shown below.

<Synthesis Example 4: Synthesis of Crosslinked P (4VP-co-S)>
In this synthesis example, a crosslinked polymer having a pyridyl group as a proton-accepting group as a repeating unit was synthesized as follows.

A column packed with basic alumina was purified through unpurified 4-vinylpyridine. Styrene was also purified in the same manner.

Purified 4-vinylpyridine (4VP) 0.663 g (6.31 mmol) as the first monomer having a proton-accepting group, N, N'-methylenebisacrylamide (MBAA) 25 as the crosslinkable second monomer .3 mg (0.164 mmol), styrene (S) 0.332 g (3.19 mmol) as a non-crosslinkable third monomer having no proton-accepting group, azobisisobutyronitrile as a radical polymerization initiator 1.1 mg (0.0067 mmol) of (AIBN) was mixed in a sample bottle to obtain a raw material solution. The mass ratio of the first monomer: the second monomer: the third monomer: the radical polymerization initiator in this raw material solution was approximately 600: 23: 300: 1. Further, the molar ratio of the first monomer: the second monomer: the third monomer: the radical polymerization initiator in this raw material solution was approximately 942: 24: 476: 1. If the polymerization proceeds according to the mixing ratio of the monomers, the proportion of the first monomer having a pyridyl group as a proton-accepting group in the repeating units of the obtained crosslinked polymer is about 65.0% by mass (≈600 /). (600 + 23 + 300)). These values are summarized in Table 1 below.

After bubbling the raw material solution with nitrogen gas for 30 minutes, the temperature was raised to 80 ° C. under normal pressure with an oil bath, and the polymerization reaction was carried out for 7 and a half hours under stirring at 500 rpm. After that, when the sample bottle was taken out from the oil bath, it was confirmed that the sample in the sample bottle was glassy.

40 mL of chloroform was added to the sample bottle containing the above sample, and the mixture was immersed for two and a half hours. Chloroform was removed after two and a half hours, the same amount of fresh chloroform was added, and immersion was performed again for two and a half hours. This chloroform dipping operation was repeated 3 times to remove unreacted monomers, small molecule oligomers and the like for purification. Since the obtained sample was swollen with chloroform, it was left on a hot plate at 50 ° C. for about 12 hours to remove this chloroform, and then dried in a vacuum dryer at 50 ° C. for 1 week. By completely removing chloroform, which is a volatile solvent, cross-linked poly (4-vinylpyridine-co-styrene) (cross-linked P (4VP-co-S)) was obtained.

The structure of the obtained crosslinked P (4VP-co-S) is shown below.

<Synthesis Example 5: Synthesis of Crosslinked P (4VP-co-S)>
In this synthesis example, a crosslinked polymer having a pyridyl group as a proton-accepting group as a repeating unit was synthesized as follows.

This synthesis example is the same as that of Synthesis Example 4 except that the mass ratio of the first monomer: the second monomer: the third monomer: the radical polymerization initiator in the raw material solution is approximately 420: 21: 410: 1. A crosslinked polymer (4-vinylpyridine-co-styrene) (crosslinked P (4VP-co-S)) was obtained. If the polymerization proceeds according to the mixing ratio of the monomers, the proportion of the first monomer having a pyridyl group as a proton-accepting group in the repeating units of the obtained crosslinked polymer is about 49.4% by mass (≈420 / ≈ 420 /). (420 + 21 + 410)). These values are summarized in Table 1 below.

<Synthesis Example 6: Synthesis of Crosslinked P (4VP-co-S)>
In this synthesis example, a crosslinked polymer having a pyridyl group as a proton-accepting group as a repeating unit was synthesized as follows.

This synthesis example is the same as that of Synthesis Example 4 except that the mass ratio of the first monomer: the second monomer: the third monomer: the radical polymerization initiator in the raw material solution is approximately 340: 25: 680: 1. A crosslinked polymer (4-vinylpyridine-co-styrene) (crosslinked P (4VP-co-S)) was obtained. If the polymerization proceeds according to the mixing ratio of the monomers, the proportion of the first monomer having a pyridyl group as a proton-accepting group in the repeating units of the obtained crosslinked polymer is about 32.5% by mass (≈340 /%). (340 + 25 + 680)). These values are summarized in Table 1 below.

<Synthesis Example 7 (Comparative Synthesis Example): Synthesis of Crosslinked PS>
In this synthesis example, a crosslinked polymer having substantially no proton-accepting group as a repeating unit was synthesized.

A column packed with basic alumina was purified by passing unrefined styrene through it.

24.8 mg (0.161 mmol) of N, N'-methylenebisacrylamide (MBAA) as a crosslinkable second monomer, styrene (S) 1 as a non-crosslinkable third monomer having no proton accepting group. 1.01 g (9.71 mmol), 1.1 mg (0.0067 mmol) of azobisisobutyronitrile (AIBN) as a radical polymerization initiator, and 0.100 g of methanol as a solvent are mixed in a sample bottle to prepare a raw material solution. Got The mass ratio of the second monomer: the third monomer: the radical polymerization initiator in this raw material solution was approximately 23: 920: 1. In addition, the molar ratio of the second monomer: the third monomer: the radical polymerization initiator in this raw material solution was approximately 24: 1449: 1. If the polymerization proceeds according to the mixing ratio of the monomers, the proportion of the first monomer as a proton-accepting group in the repeating units of the obtained crosslinked polymer should be 0% by mass (= 0 / (23 + 920)). Is. These values are summarized in Table 1 below.

After bubbling the raw material solution with nitrogen gas for 30 minutes, the temperature was raised to 80 ° C. under normal pressure by an oil bath, and the reaction was carried out under stirring at 500 rpm for 7 and a half hours. After that, when the sample bottle was taken out from the oil bath, it was confirmed that the sample in the sample bottle was glassy.

40 mL of tetrahydrofuran (THF) was added to the sample bottle containing the above sample, and the mixture was immersed for two and a half hours. After two and a half hours, THF was removed, the same amount of fresh THF was added, and immersion was performed again for two and a half hours. This THF immersion operation was repeated 3 times to remove unreacted monomers, small molecule oligomers and the like for purification. Since the obtained sample was swollen with THF, it was left on a hot plate at 50 ° C. for about 12 hours to remove this THF, and then dried in a vacuum dryer at 50 ° C. for 1 week. Cross-linked polystyrene (cross-linked PS) was obtained by completely removing THF as a volatile solvent.

The structure of the obtained crosslinked PS is shown below.

<Synthesis Example 8: Synthesis of post-crosslinked P4VP>
In this synthesis example, the pyridyl group as a proton-accepting group is repeatedly used as a repeating unit by reacting the non-crosslinking polymer (non-crosslinking P4VP) having a pyridyl group obtained in Synthesis Example 2 with a cross-linking agent as described below. The post-crosslinking polymer possessed by was synthesized.

More specifically, 1.01 g of the non-crosslinked P4VP obtained in Synthesis Example 2 described above was dissolved in 9.94 g of a methanol solvent. Add 0.0101 g of 1,4-dibromobutane as a cross-linking agent to this solution, mix well, pour into a polymethylpentene chalet (inner diameter 8.5 cm), and let stand at 50 ° C. for about 2 days to make it volatile. The solvent (methanol) was evaporated to allow the crosslinking reaction to proceed. Then, the volatile solvent was completely removed by drying at 50 ° C. for about 1 day using a vacuum dryer to obtain a post-crosslinked poly (4-vinylpyridine) (post-crosslinked P4VP) film.

The obtained post-crosslinked P4VP membrane did not dissolve in a good solvent such as methanol and swelled, indicating that this membrane was crosslinked.

The structure of the post-crosslinked P4VP is shown below.

<Example 1>
In this example, the crosslinked P4VP obtained in Synthesis Example 1 is used as the crosslinked polymer, and concentrated sulfuric acid (pKa: -3.0) (98%) is used as the plasticizer to prepare a proton conduction film. The proton conductivity was examined.

(1) Preparation of Proton Conductive Membrane 269 mg of concentrated sulfuric acid (98%) and 5.01 g of methanol were added to a beaker made of Teflon (registered trademark) having a capacity of 10 mL and mixed to obtain a methanol solution of sulfuric acid. 57.9 mg of crosslinked P4VP was immersed in this solution and allowed to stand at 50 ° C. for 2 days to introduce sulfuric acid into the crosslinked P4VP and remove methanol. The membrane thus obtained was dried in a vacuum dryer at 50 ° C. for 2 days to completely remove methanol to prepare a proton conduction membrane.

Since the mass of the obtained proton conduction membrane was 313.0 mg, it was confirmed that this membrane contained 18% by mass (57.9 mg) of crosslinked P4VP and 82% by mass (255.1 mg) of sulfuric acid. Was done. The obtained proton conduction film was a viscoelastic solid.

In the obtained proton conductive film, the crosslinked polymer is crosslinked P4VP having a pyridyl group as a proton accepting group, and the plasticizer is sulfuric acid (pKa: -3.0) which is a proton donating compound. Most of the sulfuric acid is freed with protons to form sulfate ions (anions), and most of the pyridyl groups in the crosslinked P4VP receive protons from sulfuric acid to generate pyridinium ions (cations). Conceivable.

(2) Evaluation of proton conductive film (i) Measurement of glass transition point The obtained proton conductive film has a temperature of -90 ° C to 40 ° C under the condition of a heating rate of 10 ° C / min in accordance with JIS K 7121. Differential scanning calorimetry (DSC) was performed in the range. As a result, a single glass transition point Tg-79 ° C. was shown as a proton conductive film.

(Ii) No-load static test The proton conductive film obtained above was allowed to stand for 1 hour under no load while changing the temperature, and evaluated according to the following criteria.
When neither leaks nor volatiles are found in the temperature range of -40 ° C or higher and 150 ° C or lower: A
If leaks or volatiles are found at a temperature of 100 ° C or higher: B
If leaks or volatiles are found in the region above -40 ° C: C

In the no-load leakage test for the proton conductive membrane of Example 1, no leak was observed in the temperature range of -40 ° C or higher and 150 ° C or lower, and the evaluation result was “A”, and the plasticizer was used in the operating temperature range of the battery. Was confirmed not to leak. This is because the pyridyl group in the crosslinked polymer receives the proton liberated from sulfuric acid to become a pyridinium ion, and an ionic interaction between this pyridinium ion (cation) and the sulfate ion (anion) that released the proton. It is considered that this is due to the occurrence of.

(Iii) AC impedance measurement Using a platinum net with a thickness of 0.1 mm as an electrode, the AC impedance of the obtained proton conduction film was measured.

A proton conductive film (thickness 0.13 cm, width 0.42 cm) was sandwiched between a pair of electrodes arranged so as to face each other with a distance between the electrodes of 0.70 cm. The proton conductive film sandwiched between the electrodes was placed in a natural convection constant temperature constant temperature dryer and dried under the conditions of a temperature of 50 ° C. and a relative humidity of 12% RH for 1 hour. A professional thermo-hygrometer testo635-2 (manufactured by Testo) was used to measure the relative humidity.

After waiting for the temperature inside the dryer to stabilize, the voltage is changed from ¹⁰⁶ Hz to 1 Hz using Potential / Galvanostat 4-400 (Prinston Applied Research) with FRA (Frequency Response Analysis) option. Then, the AC impedance was measured under the non-humidified condition. When the resistance value in the frequency domain where the absolute value of the resistance value was almost constant was read, it was 1.4 × 10 ² Ω.

Further, when the proton conductivity of this proton conductive film was determined by the following mathematical formula (1), it was 87 mS / cm, and it was confirmed that this proton conductive film showed high proton conductivity.
Proton conductivity = distance between electrodes / (thickness of membrane x width of membrane x resistance value) (1)

Next, when the measurement conditions were changed to a temperature of 80 ° C. and a relative humidity of 3.5% RH, and AC impedance measurement was performed, the resistance value in the frequency region where the absolute value of the resistance value was almost constant was 1.0 × 10. It was ² Ω, the proton conductivity was 120 mS / cm, and the proton transmission rate was high.

Further, the AC impedance was measured by changing the temperature and relative humidity at the time of measurement, and the resistance value and the proton conductivity in the frequency region where the absolute value of the resistance value was almost constant were obtained. As a result, at a temperature of 95 ° C. and a relative humidity of 2.5% RH, the resistance value is 8.7 × 10 ¹ Ω and the proton conductivity is 140 mS / cm; at a temperature of 110 ° C. and a relative humidity of 2.0% RH, the resistance value is 140 mS / cm. The resistance is 8.3 x 10 ¹ Ω and the proton conductivity is 150 mS / cm; at a temperature of 120 ° C and a relative humidity of 1.8% RH, the resistance is 7.8 x 10 ¹ Ω and the proton conductivity is 160 mS. It was / cm, and the proton conductivity showed a high value under all the measurement conditions.

During the measurement of the AC impedance, the proton conductive film of this example showed no leaks, did not flow, maintained the film shape, and was a viscoelastic solid.

<Examples 2 and 3 and Comparative Example 1>
A proton conductive film was prepared and evaluated in the same manner as in Example 1 except that the amounts of the crosslinked polymer and the plasticizer used were changed as shown in Table 2 below. The evaluation results are shown in Table 2 below.

<Example 4>
In this example, a proton conduction film was prepared and evaluated using the crosslinked P4VP obtained in Synthesis Example 1 as the crosslinked polymer and phosphoric acid (pKa: 2.1) (85%) as the plasticizer. ..

(1) Preparation of Proton Conduction Film In a beaker made of Teflon (registered trademark) having a capacity of 10 mL, 112 mg of phosphoric acid (85%) and 5.01 g of methanol were put and mixed to obtain a methanol solution of phosphoric acid. 23.6 mg of crosslinked P4VP was immersed in this solution and allowed to stand at 50 ° C. for 2 days to introduce phosphoric acid into the crosslinked P4VP and remove methanol. The membrane thus obtained was dried in a vacuum dryer at 50 ° C. for 2 days to completely remove methanol to prepare a proton conduction membrane.

Since the mass of the obtained proton conduction membrane was 119.0 mg, this membrane may contain 20% by weight (23.6 mg) of crosslinked P4VP and 80% by weight (95.4 mg) of phosphoric acid. confirmed. The obtained proton conduction film was a viscoelastic solid.

In the obtained proton conductive film, the crosslinked polymer was a crosslinked P4VP having a pyridyl group as a proton accepting group, and the plasticizer was phosphoric acid (pKa: 2.1) which is a proton donating compound. A part of phosphoric acid is freed with protons to become phosphate ions (cations), and the pyridyl group in the crosslinked P4VP accepts protons from phosphoric acid to generate pyridinium ions (cations). It is thought that there is.

(2) Evaluation of Proton Conduction Membrane The obtained proton conduction membrane was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2 below.

<Comparative Example 2>
In Comparative Example 2, a proton conductive film was prepared and evaluated using the crosslinked P4VP obtained in Synthesis Example 1 as the crosslinked polymer and isopropylmalonic acid (IPMA) (pKa: 2.9) as the plasticizer. ..

(1) Preparation of Proton Conductive Membrane 49 mg of IPMA and 5.01 g of methanol were placed in a beaker made of Teflon (registered trademark) having a capacity of 10 mL and mixed to obtain a methanol solution of IPMA. 37.4 mg of crosslinked P4VP was immersed in this solution and allowed to stand at 50 ° C. for 2 days to introduce IPMA into the crosslinked P4VP and remove methanol. The membrane thus obtained was dried in a vacuum dryer at 50 ° C. for 2 days to completely remove methanol to prepare a proton conduction membrane.

Since the mass of the obtained proton conduction membrane was 186.0 mg, it was confirmed that this membrane contained 20% by mass (37.4 mg) of crosslinked P4VP and 80% by mass (148.6 mg) of IPMA. Was done. The obtained proton conduction film was a viscoelastic solid.

In the obtained proton conductive membrane, the crosslinked polymer is a crosslinked P4VP having a pyridyl group as a proton accepting group, and the plasticizer is IPMA (pKa: 2.9) which is a proton donating compound. Some of the carboxyl groups in IPMA are freed to form carboxylate ions (anions), and the pyridyl groups in the crosslinked P4VP receive protons from IPMA to generate pyridinium ions (cations). it seems to do.

(2) Evaluation of Proton Conduction Membrane The obtained proton conduction membrane was evaluated in the same manner as in Example 1.

In Comparative Example 2, in the no-load static test, when the temperature became 100 ° C. or higher, the odor of IPMA began to drift around the proton conductive membrane. From this, it was found that the plasticizer evaporates in the temperature range of at least 100 ° C. or higher. Therefore, the AC impedance was measured at 50 ° C., 80 ° C., and 95 ° C., and not at 110 ° C. and 120 ° C. The evaluation results are shown in Table 2 below.

<Comparative Example 3>
In Comparative Example 3, the non-crosslinked P4VP obtained in Synthesis Example 2 was used instead of the crosslinked P4VP obtained in Synthesis Example 1, and sulfuric acid (pKa: -3.0) (98%) was used as a plasticizer. , I tried to prepare a proton conductive film.

A mixed solution was prepared by adding 32.8 mg of P4VPP4VP, 133 mg of sulfuric acid (98%), and 4.16 g of methanol to a beaker made of Teflon (registered trademark) having a capacity of 10 mL and mixing them. The solution was allowed to stand on a hot plate at 50 ° C. for 2 days to remove methanol. Then, the residue after removing the methanol was dried in a vacuum dryer at 50 ° C. for 2 days to completely remove the methanol, thereby obtaining a sample of Comparative Example 3.

The obtained sample was fluid and did not have a film shape. It is considered that this is because the polymer could not maintain the film shape because it was not crosslinked.

Therefore, the sample obtained in this comparative example could not be evaluated.

<Example 5>
In this example, a proton conduction membrane was prepared and evaluated using the crosslinked PVIm obtained in Synthesis Example 3 as the crosslinked polymer and sulfuric acid (pKa: -3.0) (98%) as the plasticizer. ..

(1) Preparation of Proton Conductive Membrane 166 mg of sulfuric acid (98%) and 5.10 g of methanol were put into a beaker made of Teflon (registered trademark) having a capacity of 10 mL and mixed to obtain a methanol solution of sulfuric acid. 39.8 mg of solid crosslinked PVIm was immersed in this solution and allowed to stand at 50 ° C. for 2 days to introduce sulfuric acid into the crosslinked PVIm and remove methanol. The membrane thus obtained was dried in a vacuum dryer at 50 ° C. for 2 days to completely remove methanol to prepare a proton conduction membrane.

Since the mass of the obtained proton conduction membrane was 203.0 mg, it was confirmed that this membrane contained 20% by mass (39.8 mg) of crosslinked PVIm and 80% by mass (163.2 mg) of sulfuric acid. Was done. The obtained proton conduction film was a viscoelastic solid.

In the obtained proton conductive film, the crosslinked polymer is a crosslinked PVIm having an imidazole group as a proton accepting group, and the plasticizer is sulfuric acid (pKa: -3.0) which is a proton donating compound. It is considered that sulfuric acid is liberated into sulfate ions (anions), and the pyridyl group in the crosslinked P4VP receives protons from sulfuric acid to generate imidazolium ions (cations).

(2) Evaluation of Proton Conduction Membrane The obtained proton conduction membrane was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2 below.

<Example 6>
In Example 6, the crosslinked P (4VP-co-S) obtained in Synthesis Example 4 was used as the crosslinked polymer, and concentrated sulfuric acid (pKa: -3.0) (98%) was used as the plasticizer, and protons were used. Conductive membranes were prepared and evaluated.

(1) Preparation of Proton Conductive Membrane To a beaker made of Teflon (registered trademark) having a capacity of 10 mL, 194 mg of concentrated sulfuric acid (98%) and 4.27 g of methanol were added, and the above-mentioned crosslinked P (4VP-co-S) was added to the solution. 48.6 mg was immersed. Then, it was allowed to stand on a hot plate at 50 ° C. for about 2 days to introduce sulfuric acid into the crosslinked P (4VP-co-S) and remove methanol. Then, the methanol was completely removed by drying in a vacuum dryer at 50 ° C. for about 2 days to obtain a proton conductive film.

Since the mass of the obtained proton conduction membrane was 237 mg, it was found that this membrane contained 20% by mass of crosslinked P (4VP-co-S) and 80% by mass of sulfuric acid. The obtained proton conductive film was a viscoelastic solid.

In the obtained proton conductive film, the crosslinked polymer is crosslinked P (4VP-co-S) having a pyridyl group as a proton accepting group, and the plasticizer is sulfuric acid (pKa: -3) which is a proton donating compound. .0). In sulfuric acid, protons are liberated to form sulfate ions (anions), and the pyridyl group in the crosslinked P (4VP-co-S) accepts protons from sulfuric acid to generate imidazolium ions (cations). it seems to do.

(2) Evaluation of Proton Conduction Membrane The obtained proton conduction membrane was evaluated in the same manner as in Example 1. The proton conductivity was evaluated at 110 ° C. and 120 ° C. The evaluation results are shown in Table 2 below.

<Example 7>
In this example, the crosslinked P (4VP-co-S) obtained in Synthesis Example 5 is used as the crosslinked polymer, and sulfuric acid (pKa: -3.0) (98%) is used as the plasticizer to conduct proton conduction. Membranes were prepared and evaluated.

(1) Preparation of Proton Conduction Membrane Example 6 except that 195 mg of concentrated sulfuric acid (98%), 4.21 g of methanol and 48.7 mg of the solid crosslinked P (4VP-co-S) obtained in Synthesis Example 5 were used. A proton conductive film was prepared in the same manner as above.

Since the mass of the obtained proton conduction membrane was 241 mg, it was found that this membrane contained 20% by mass of crosslinked P (4VP-co-S) and 80% by mass of sulfuric acid. The obtained proton conductive film was a viscoelastic solid.

(2) Evaluation of Proton Conduction Membrane The obtained proton conduction membrane was evaluated in the same manner as in Example 1. The proton conductivity was evaluated at 110 ° C. and 120 ° C. The evaluation results are shown in Table 2 below.

<Example 8>
In this example, the crosslinked P (4VP-co-S) obtained in Synthesis Example 6 is used as the crosslinked polymer, and sulfuric acid (pKa: -3.0) (98%) is used as the plasticizer to conduct proton conduction. Membranes were prepared and evaluated.

(1) Preparation of Proton Conduction Membrane Example 6 except that 121 mg of concentrated sulfuric acid (98%), 4.07 g of methanol and 30.0 mg of the solid crosslinked P (4VP-co-S) obtained in Synthesis Example 6 were used. A proton conductive film was prepared in the same manner as above.

Since the mass of the obtained proton conduction membrane was 147 mg, it was found that this membrane contained 20% by mass of crosslinked P (4VP-co-S) and 80% by mass of sulfuric acid. The obtained proton conductive film was a viscoelastic solid.

(2) Evaluation of Proton Conduction Membrane The obtained proton conduction membrane was evaluated in the same manner as in Example 1. The proton conductivity was evaluated at 110 ° C. and 120 ° C. The evaluation results are shown in Table 2 below.

<Comparative Example 4>
In Comparative Example 4, crosslinked PS obtained in Synthesis Example 7 (Comparative Synthesis Example) having substantially no nitrogen-containing heterocycle as a repeating unit was used as the crosslinked polymer, and concentrated sulfuric acid (pKa: -3) was used as the plasticizer. .0) (98%) was used to attempt to prepare a proton conductive film.

(2) Preparation of Proton Conductive Membrane To a beaker made of Teflon (registered trademark) having a capacity of 10 mL, 164 mg of concentrated sulfuric acid (98%) and 4.77 g of THF were added, and the crosslink obtained in Synthesis Example 7 (Comparative Synthesis Example) was added to the solution. 41.3 mg of PS solid was immersed. Then, it was allowed to stand on a hot plate at 50 ° C. for about 2 days to try to introduce sulfuric acid into the crosslinked PS and remove THF. Although THF was evaporated, sulfuric acid was hardly absorbed by the crosslinked PS, and the sulfuric acid and the crosslinked PS were separated, so that a proton conduction film could not be obtained.

It is considered that the reason why sulfuric acid was not absorbed by the cross-linked PS is that the cross-linked PS has substantially no proton-accepting group in the repeating unit and has no affinity for sulfuric acid.

<Example 9>
In Example 9, the post-crosslinked P4VP obtained in Synthesis Example 8 was used as the crosslinked polymer, and concentrated sulfuric acid (pKa: -3.0) (98%) was used as the plasticizer to prepare and evaluate a proton conduction membrane. bottom.

(1) Preparation of Proton Conduction Film A solution of 554 mg of concentrated sulfuric acid (98%) in 5.78 g of methanol is poured into a Teflon (registered trademark) container (inner diameter 4 cm), and 136 mg of the above-mentioned post-crosslinked P4VP is immersed in the solution. The volatile solvent (methanol) was evaporated by allowing the mixture to stand at 50 ° C. for about 2 days. Then, the volatile solvent was completely removed by drying at 50 ° C. for about 1 day using a vacuum dryer to obtain 670 mg of a sample in which the post-crosslinked P4VP was swollen with H ₂ SO ₄ . The weight concentration of H ₂ SO ₄ was 80% by mass.

The film thickness of the obtained proton conductive film was 0.35 mm. Moreover, this proton conduction film was a viscoelastic solid.

(2) Evaluation of Proton Conductive Film The obtained proton conductive membrane was evaluated for proton conductivity in the same manner as in Example 1. The evaluation results of the proton conductivity are shown in Table 2 below.

(3) Tensile test The obtained film-shaped sample was punched out with a punching blade type to prepare a dogbone type test piece having a width of 4 mm. The measuring device is AGS-X, 50N load cell, 50N clip type gripper manufactured by Shimadzu Corporation, and the distance between the grippers is 5.9 mm, and the initial strain rate is 0.33 / s (tensile speed 1.9 mm / s). A test was conducted. The stress-strain curve as a result of the tensile test is shown in FIG.

In Example 9, the results of the obtained Young's modulus, maximum stress, elongation at break, and internal area value (index of material toughness) of the stress-strain curve are 0.10 MPa, 0.054 MPa, 60%, and 0, respectively. It was ^.021 MJ / m3.

The Young's modulus was obtained from the initial gradient of the stress-strain curve (strain within 10%), the maximum stress was obtained from the maximum value of stress, and the fracture elongation was determined from the elongation at the time of fracture.

From the results of the tensile test of the proton conductive film of Example 9 obtained above, it was found that the proton conductive film of Example 9 was a flexible solid film.

As shown in Tables 1 and 2, having the proton conductive membranes of Examples 1-9, i.e., a crosslinked polymer having a substantial proportion of proton-accepting groups and a suitable proton-donating plasticizer, and The proton conductive film, which is a viscoelastic solid, had no leaks and volatile substances in the temperature range of −40 ° C. to 150 ° C., and had good proton conductivity.

On the other hand, it has the proton conductive film of Comparative Example 1, that is, a crosslinked polymer having a substantially proportion of proton-accepting groups and an appropriate plasticizer having a proton-donating property, and has a low plasticizer content, so that it has viscoelasticity. The proton conductive film, which is a glassy solid rather than a solid, had low proton conductivity.

Further, the proton conductive film of Comparative Example 2, that is, the proton conductive film having a crosslinked polymer having a proton-accepting group in a substantial ratio and a proton-donating plasticizer and having a plasticizer pKa too large, is proton-conducting. Was low.

Further, in Comparative Example 3, an attempt was made to form a proton conductive film using a polymer having a proton-accepting group in a substantial ratio and a proton-donating plasticizer, but this polymer is a non-crosslinked polymer. The material showed fluidity and could not be formed into a film shape.

Further, in Comparative Example 4, an attempt was made to form a proton conductive film using a crosslinked polymer and a proton-donating plasticizer, but the crosslinked polymer had substantially no proton-accepting group, and thus protons. The donor plasticizer was not absorbed by the polymer and therefore a proton conductive film could not be obtained.

In Examples 6 to 8 (Synthesis Examples 4 to 6) in which the ratio of the first monomer having a proton-accepting group was changed, the ratio of the first monomer decreased from 65.0 mol% to 32.5 mol%. Therefore, it is considered that the concentration of free protons in the membrane increased, and as a result, the proton conductivity increased to about 200 mS / cm.

<Reference example 1>
In Reference Example 1, the tendency of the glass transition point (Tg) to change when the molar ratio of the proton-donating compound (sulfuric acid) to the proton-accepting group (pyridyl group) was changed was investigated.

As the polymer having a proton-accepting group (pyridyl group) of Reference Example 1, the non-crosslinked polymer (non-crosslinked P4VP) of Synthesis Example 2 described above was used.

The above non-crosslinked P4VP and concentrated sulfuric acid (pKa: −3.0) (98%) were mixed at different molar ratios, and the respective glass transition points were measured. The results are shown in Table 3 and FIG.

As shown in Table 3 and FIG. 3, when the molar ratio of sulfuric acid to the pyridyl group is 0.12 to 0.71, the Tg of the mixture of uncrosslinked P4VP and sulfuric acid is the Tg of the uncrosslinked P4VP itself. There was a tendency to go up. It is considered that this is because most of the sulfuric acid formed an acid-base complex with the pyridyl group of the non-crosslinked P4VP in which segment motion was less likely to occur.

On the other hand, when the molar ratio of sulfuric acid to the pyridyl group begins to exceed 1, for example, when the molar ratio of sulfuric acid to the pyridyl group is 1.1, the Tg of the mixture of uncrosslinked P4VP and sulfuric acid is significantly reduced. A tendency was obtained. It is considered that this is because sulfuric acid functions as a plasticizer when the molar ratio of sulfuric acid to the pyridyl group exceeds 1, and the segment movement of the polymer chain is likely to be actively generated.

The result obtained above is not due to the number of moles of protons contained in sulfuric acid, but to the number of moles of sulfuric acid itself. The above results are considered applicable to all proton donating compounds.

<Reference example 2>
In Reference Example 2, the change tendency of the proton conductivity of the proton conductive membrane when the molar ratio of the proton donating compound (sulfuric acid) to the proton accepting group (pyridyl group) changed at 120 ° C. was investigated.

In Reference Example 2, the crosslinked P4VP obtained in Synthesis Example 1 described above was used, and concentrated sulfuric acid (pKa: -3.0) (98%) as a plasticizer was used to change the sulfuric acid content. Except for this, a proton conductive film was prepared in the same manner as in Example 9, and the proton conductivity at 120 ° C. was examined. The results are shown in FIG.

As shown in FIG. 4, when the molar ratio of sulfuric acid to the pyridyl group is less than 1.1 (sulfuric acid content 50% by mass), the resistance is high and the proton conductivity cannot be estimated by impedance measurement. (Indicated by the dotted line).

On the other hand, as the molar ratio of sulfuric acid to the pyridyl group increases from 1.3 (sulfuric acid content 55% by mass) to 1.6 (sulfuric acid content 60% by mass), the proton conductivity increases. It turned out that it increased by two to three digits. It is considered that this is because a rapid increase in proton conductivity was observed due to an increase in the concentration of free protons derived from an excess amount of sulfuric acid that is not used for acid-base complex formation.

From the results of Reference Examples 1 and 2 described above, when a proton-donating compound is impregnated into a crosslinked polymer having a proton-accepting group in the side chain, a larger amount of protons is donated than the number of moles of the proton-accepting group. It was found that when a sex compound was contained, the glass transition point was sharply lowered and the proton conductivity under no humidification was sharply increased.

Claims (10)

Contains crosslinked polymers and plasticizers
The crosslinked polymer has a proton-accepting group of 10 mol% or more of the repeating units constituting the crosslinked polymer.
The plasticizer contains a proton donating compound having a pKa of 2.5 or less.
It is a viscoelastic solid in the temperature range of 50 ° C or higher and 120 ° C or lower , and
The glass transition point is 30 ° C or lower,
Proton conduction membrane. The proton conduction film according to claim 1, wherein the content of the plasticizer is 60 parts by mass or more and 90 parts by mass or less when the total of the crosslinked polymer and the plasticizer is 100 parts by mass. The proton conductive membrane according to claim 1 or 2, wherein the proton-donating compound is at least one selected from sulfuric acid and phosphoric acid. The proton conduction membrane according to any one of claims 1 to 3, wherein the proton-accepting group is a nitrogen-containing heterocyclic group. The invention according to any one of claims 1 to 4 , wherein the crosslinked polymer is a copolymer of a first monomer which is a vinyl-based monomer having a proton-accepting group and a second monomer which is a crosslinked vinyl monomer. Monomer conduction film. The proton conductive membrane according to any one of claims 1 to 5 , wherein the proton conductivity of the proton conductive membrane is 7.4 mS / cm or more at 50 ° C. The proton conduction membrane according to any one of claims 1 to 6 , wherein the molar ratio of the proton-donating compound to the proton-accepting group is 1.0 or more and 10.0 or less. A fuel cell having the proton conductive film according to any one of claims 1 to 7 . A method for producing a proton conductive film containing a crosslinked polymer and a plasticizer.
The crosslinked polymer has a proton-accepting group of 10 mol% or more of the repeating units constituting the crosslinked polymer.
The plasticizer contains a proton donating compound having a pKa of 2.5 or less.
The proton conductive film is a viscoelastic solid in a temperature range of 50 ° C. or higher and 120 ° C. or lower, and the method is a precursor polymer obtained by polymerizing a first monomer which is a vinyl-based monomer having a proton-accepting group. And by adding a cross-linking agent to the precursor polymer to cross-link the precursor polymer, the present invention comprises obtaining the cross-linked polymer.
A method for manufacturing a proton conductive membrane. A method for producing a proton conductive film containing a crosslinked polymer and a plasticizer.
The crosslinked polymer has a proton-accepting group of 10 mol% or more of the repeating units constituting the crosslinked polymer.
The plasticizer contains a proton donating compound having a pKa of 2.5 or less.
The proton conductive film is a viscous elastic solid in a temperature range of 50 ° C. or higher and 120 ° C. or lower, and the method is a first monomer which is a vinyl-based monomer having a proton-accepting group and a crosslinkable vinyl monomer. The cross-linking polymer is obtained by polymerizing and cross-linking with the second monomer.
A method for manufacturing a proton conductive membrane.

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