JP2007119654A - Proton-conductive block copolymer, its crosslinked material and proton-conductive film and fuel cell using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a proton-conductive block copolymer used for fuel cells satisfying both of the water resistance and the high proton conductivity over a long period, its crosslinked product and a proton-conductive film using those, and a fuel cell using the film. <P>SOLUTION: The present invention provides a proton-conductive block copolymer in which the product of proton conductivity (26%RH, 80°C) with ion exchange group equivalent (EW=polymer molecular weight/protonic acid group amount) is ≥0.1, a proton-conductive block copolymer having recurring structure units with a specific structure, crosslinked products of these proton-conductive block copolymers and further provides a proton-conductive film using the proton-conductive block copolymer and its crosslinked product, and a fuel cell. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ion conductive proton conductive block copolymer aromatic resin used in a fuel cell using hydrogen, alcohol or the like as a fuel, a polymer membrane obtained by using the same, and a fuel cell.

A polymer electrolyte fuel cell is a fuel cell that uses a proton-conducting polymer as an electrolyte, and the chemical energy of the fuel is converted into electrical energy by electrochemically oxidizing hydrogen or methanol or other fuel using oxygen or air. It is to be converted and extracted. The polymer electrolyte fuel cell includes a type using pure hydrogen supplied from a cylinder, a pipe, or the like as a fuel, and a type using hydrogen generated from gasoline or methanol by a reformer. In addition, a direct methanol fuel cell (DMFC) that directly generates power using a methanol aqueous solution as a fuel has been developed.
A polymer electrolyte fuel cell includes a polymer electrolyte membrane and a positive electrode and a negative electrode arranged in contact with both sides thereof. Fuel hydrogen or methanol is electrochemically oxidized at the negative electrode to generate protons and electrons. This proton moves in the polymer electrolyte membrane to the positive electrode to which oxygen is supplied. On the other hand, electrons generated at the negative electrode pass through a load connected to the battery and flow to the positive electrode, where protons and electrons react to generate water at the positive electrode. Therefore, high proton conductivity is required for the electrolyte membrane.
In particular, polymer fuel cells (PEFC) using hydrogen as a fuel are required to have proton conductivity under low humidification because there is no water in the fuel.

As a polymer electrolyte membrane having high proton conductivity, development of a non-fluorine polymer compound has been promoted. However, tertiary carbon having a main chain structure is susceptible to radical attack, and α This causes a problem that the battery characteristics deteriorate with time. For this reason, a large number of protonic acid group-containing polymers having no aliphatic chain in the main chain, that is, aromatic hydrocarbons, have been developed. Among them, it has been reported that a membrane made of sulfonated polyether ether ketone is excellent in heat resistance and chemical durability and can withstand long-time use as a polymer electrolyte (for example, Non-Patent Document 1). .
In order to increase the proton conductivity of these proton acid group-containing aromatic hydrocarbon polymer membranes, it is necessary to increase the amount of proton acid groups introduced, that is, to reduce the ion exchange group equivalent. It is known that when the introduction amount is increased, the hydrophilicity is increased at the same time, and the water absorption is increased or becomes water-soluble (for example, Patent Document 1). Since a fuel cell produces water as a by-product by the reaction of fuel and oxygen, a water-soluble resin cannot be used as a polymer electrolyte membrane for a fuel cell. In addition, even if it is not water-soluble, if water absorption is high, problems such as swelling of the film, a decrease in strength, and permeation of methanol from the negative electrode to the positive electrode through the absorbed water occur.

Therefore, a method for improving water resistance and reducing water absorption by introducing a crosslinked structure into the polymer electrolyte membrane has been developed.
For example, a crosslinking method using a sulfonate bond obtained by desulfurization condensation of sulfonic acids in a polyether ether ketone membrane has been reported (for example, Patent Document 2), which is a crosslinking mechanism accompanied by elimination of sulfuric acid, There are problems that the crosslink density is different between the film surface and the inside of the film or the back surface of the film, it is difficult to increase the film thickness, voids are formed in the film, and the production apparatus is corroded by the desorbed acidic gas. Further, the membrane obtained by the crosslinking mechanism using these protonic acid groups has a problem that when the crosslinking density is improved, the protonic acid groups decrease (the ion exchange group equivalent increases) and the ionic conductivity decreases.

  As a crosslinking mechanism that does not involve elimination of sulfuric acid or hydrochloric acid, the chlorosulfonic acid group of chlorosulfonated polyetherketone and allylamine are reacted to form an allyl group bonded with a sulfonamide group. Although the mechanism of making it report is reported (for example, patent document 3), in order to improve a crosslinking density, it is necessary to reduce a proton acid group (increase an ion exchange group equivalent). In addition, the sulfonamide bond that binds the crosslinking group has a problem that it is susceptible to hydrolysis.

A method of crosslinking a carbonyl group and an alkyl group directly bonded to an aromatic ring is disclosed as one having a crosslinking mechanism that is not derived from a proton acid group and does not involve a leaving component (for example, Patent Document 4). Since the part into which the group is introduced is not specified, if the crosslinking proceeds too much in the part where the proton acid group exists, the movement of the polymer chain is restricted by the crosslinking, or the water absorption necessary for proton conduction decreases. In some cases, the conductivity was reduced.
However, in any of the methods, a polymer electrolyte membrane that sufficiently satisfies both water resistance and high proton conductivity has not been obtained, and further performance improvement has been demanded.

Japanese Patent Laid-Open No. 10-45913 JP 2000-501223 Gazette JP-A-6-93114 JP 2003-217342 A Masaru Honma, Abstracts of Lectures of the 3rd Separation of Sciences and Technology "Basics and Applications of Polymer Membrane Fuel Cells" p17 (1999)

  An object of the present invention is to provide a proton conductive block copolymer, a cross-linked product thereof, a proton conductive membrane and a fuel cell using the same, which are used in a fuel cell, which can achieve both water resistance and high proton conductivity for a long period of time. It is in.

The present inventors have found that a polymer electrolyte membrane obtained from a specific proton conductive block copolymer can achieve both water resistance and high proton conductivity over a long period of time, and has completed the present invention.
That is, this invention is specified by the matter described in the following [1]-[8].

[式（１）中、Ａ_１は直接結合，−ＳＯ_２−または−ＣＯ−であり、式（１）中の芳香環の水素原子は、−Ｃ_ｍＨ_２ｍ＋１（ｍは１〜１０の整数）、−Ｆ、−ＣＦ_３、−Ｓｉ（ＣＨ_３）_３、−ＯＳｉ（ＣＨ_３）_３または−ＣＮに置換されていても良い。
式（２）中、Ｒ_１はプロトン酸基である。式（２）中、Ｂ_１は−ＳＯ_２−または−ＣＯ−であり、式（２）中の芳香環の水素原子は、プロトン酸基に置換されていても良い。
Ｘ_１及びＹ_１は、式（３）〜（５）のいずれかであり、且つ、の少なくとも１つは式（４）あるいは（５）で表されるナフタレン環構造であり、式（３）、（４）および（５）で表されるＹ_１の芳香環の水素原子はプロトン酸基に置換されていても良い。
式（３）中、のＤ_１およびＤ_２はそれぞれ独立して直接結合，−ＣＨ_２−、−Ｃ（ＣＨ_３）_２−、−Ｃ（ＣＦ_３）_２−、−Ｏ−、−ＳＯ_２−または−ＣＯ−であり、aおよびｂはそれぞれ独立して０または１を示す。
式（３）、（４）および（５）中の芳香環の水素原子は−Ｃ_ｍＨ_２ｍ＋１（ｍは１〜１０の整数）、−Ｆ、−ＣＦ_３、−Ｓｉ（ＣＨ_３）_３、−ＯＳｉ（ＣＨ_３）_３または−ＣＮに置換されていても良い。］
[３]ブロック（Ａ）のＡ_１及びブロック（Ｂ）のＢ_１が−ＣＯ−であり、且つ、式（３）で表されるＸ_１あるいはＹ_１の芳香環の水素原子が−Ｃ_ｍＨ_２ｍ＋１（ｍは１〜１０の整数）で置換された下記式（６）であり、Ｘ_１及びＹ_１のいずれか一方が式（４）、（５）で表されるナフタレン環構造で他方が式（６）である架橋型プロトン伝導性ブロック共重合体であることを特徴とする前記[２]記載のプロトン伝導性ブロック共重合体。

[式（６）中の芳香環の水素原子が−Ｃ_ｍＨ_２ｍ＋１（ｍは１〜１０の整数）、−Ｆ、−ＣＦ_３、−Ｓｉ（ＣＨ_３）_３、−ＯＳｉ（ＣＨ_３）_３または−ＣＮに置換されていても良い。]
［４］ブロック（Ａ）及びブロック（Ｂ）の一般式（３）又は式（６）であらわされるＸ_１又はＹ_１のａが０である前記［２］又は[３]記載のプロトン伝導性ブロック共重合体。
［５］プロトン酸基が、−Ｃ_ｎＨ_２ｎ−ＳＯ_３Ｚ、−Ｃ_ｎＨ_２ｎ−ＰＯ_３Ｚ_２、−Ｃ_ｎＨ_２ｎ−ＣＯＯＺ（ｎは０〜１０の整数、ＺはＨ、ＮａまたはＫである）のいずれかであることを特徴とする前記［１］〜［４］のいずれか一つに記載のプロトン伝導性ブロック共重合体。
［６］前記［１］〜［５］のいずれか一つに記載のプロトン伝導性ブロック共重合体を架橋してなるプロトン伝導性ブロック共重合架橋体。
［７］前記［１］〜［６］のいずれか一つに記載のプロトン伝導性ブロック共重合体あるいはプロトン伝導性ブロック共重合架橋体を含んでなるプロトン伝導膜。
［８］前記［７］記載のプロトン伝導膜を用いてなる燃料電池。 [1] The product of proton conductivity (26% RH, 80 ° C.) and ion exchange group equivalent (EW = polymer molecular weight / proton acid group amount) is 0.1 or more, and contains a block having a proton acid group A proton conductive block copolymer.
[2] Proton comprising a block (A) having a repeating structural unit represented by the general formula (1) and a block (B) having a repeating structural unit represented by the general formula (2) Conductive block copolymer.

[In the formula (1), A ₁ is a direct bond, —SO ₂ — or —CO—, and the hydrogen atom of the aromatic ring in the formula (1) is —C _m H _{2m + 1} (m is an integer of 1 to 10 ), -F, -CF ₃ , -Si (CH ₃ ) ₃ , -OSi (CH ₃ ) ₃ or -CN.
In formula (2), R ₁ is a protonic acid group. In Formula (2), B ₁ is —SO ₂ — or —CO—, and the hydrogen atom of the aromatic ring in Formula (2) may be substituted with a proton acid group.
X ₁ and Y ₁ are any one of formulas (3) to (5), and at least one of them is a naphthalene ring structure represented by formula (4) or (5), and the formula (3) , (4) and (5), the hydrogen atom of the aromatic ring of Y ₁ may be substituted with a proton acid group.
In formula (3), D ₁ and D ₂ are each independently a direct bond, —CH ₂ —, —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ —, —O—, —SO _2. -Or -CO-, and a and b each independently represent 0 or 1.
Equation (3), (4) and a hydrogen atom of the aromatic ring in (5) is _-C m _{H 2m +} 1 (m is an integer of from 1 to _10), - F, -CF 3, -Si _{(CH 3)} 3, -OSi _{(CH 3)} 3 or may be substituted to -CN. ]
[3] a _{B 1} block (A) of _{A 1} and block (B) is -CO-, and, -C hydrogen atom of the aromatic ring of _{X 1} or _{Y 1} of the formula (3) _m It is the following formula (6) substituted with H _{2m + 1} (m is an integer of 1 to 10), and _one of X ₁ and Y ₁ is the naphthalene ring structure represented by formulas (4) and (5), and the other The proton conductive block copolymer according to the above [2], wherein is a cross-linked proton conductive block copolymer represented by the formula (6).

Expression _-C hydrogen atom of the aromatic ring in _{(6) m H 2m + 1} (m is an integer of from 1 to _{10), - F, -CF 3,} -Si (CH 3) 3, -OSi (CH 3) 3 Alternatively, it may be substituted with -CN. ]
[4] The proton conductivity according to the above [2] or [3], wherein a of X ₁ or Y ₁ represented by the general formula (3) or the formula (6) of the block (A) and the block (B) is 0 Block copolymer.
[5] protonic acid _{group, -C n H 2n -SO 3 Z} , -C n H 2n -PO 3 Z 2, -C n H 2n -COOZ (n is an integer of 0, Z is H, Na Or K). The proton conductive block copolymer according to any one of [1] to [4], wherein the proton conductive block copolymer is any one of the above.
[6] A proton conductive block copolymer crosslinked product obtained by crosslinking the proton conductive block copolymer according to any one of [1] to [5].
[7] A proton conducting membrane comprising the proton conducting block copolymer or the proton conducting block copolymer crosslinked product according to any one of [1] to [6].
[8] A fuel cell using the proton conducting membrane according to [7].

The proton conductive block copolymer and its cross-linked proton conductive block copolymer of the present invention have a small sulfonic acid because the product of proton conductivity and ion exchange group equivalent (polymer molecular weight / protonic acid group amount) is large. High proton conductivity can be exhibited by the base amount. If the amount of the sulfonic acid group is small, it is possible to suppress the amount of water absorption and the water absorption expansion, and it can be used without any problem even in the PEFC operated under low humidification. That is, the proton conductive block copolymer and its cross-linked product of the present invention are suitable as an electrolyte membrane material that can achieve both water resistance and high proton conductivity for a long period of time.
The electrolyte membrane using the proton conductive block copolymer of the present invention or a crosslinked proton conductive block copolymer thereof is excellent in water resistance and a phase composed of a hydrophilic block having a proton acid group responsible for proton conduction. While the phase interface is appropriately separated from the hydrophobic block with small water absorption expansion, the phase interface is bonded with the same molecule, so that dissolution of the block responsible for proton conduction in water and water absorption expansion are suppressed. There is no peeling. The effect is particularly great when the structure has a naphthalene ring structure with excellent orientation. That is, in the case where the hydrophilic phase has a naphthalene structure, the hydrophilic block aggregates due to the good orientation of the naphthalene ring and the sulfonic acid group forms a path for protons. High proton conductivity can be obtained without increasing the amount, and the water resistance is excellent. In addition, since protonic acid groups are oriented, high proton conductivity can be maintained even under low humidification. Furthermore, by introducing a crosslinking group into the hydrophobic block portion and crosslinking, the water absorption expansion of the hydrophobic block phase can be reduced and the water resistance can be improved. On the other hand, when the hydrophobic phase has a naphthalene structure, the good orientation of the naphthalene ring improves the packing of the hydrophobic block, thereby reducing the water absorption expansion of the hydrophobic block phase and improving the water resistance. Can do. Furthermore, water absorption expansion can be suppressed by introducing a crosslinking group. Therefore, by using the proton conductive block copolymer of the present invention or a crosslinked proton conductive block copolymer of the present invention for the proton conductive membrane, it is difficult for a decrease in proton conductivity or a decrease in power generation efficiency due to water absorption expansion. An efficient and reliable fuel cell can be obtained. In addition, by suppressing the water absorption expansion due to the good orientation of the naphthalene ring, it is possible to suppress the permeation of fuel such as methanol and hydrogen used in fuel cells. A fuel cell can be obtained.

  Hereinafter, the proton conductive block copolymer according to the present invention, the cross-linked product thereof, and the proton conductive membrane for fuel cell and the fuel cell using the same will be described in detail.

Proton Conductive Block Copolymer with Proton Conductivity and Ion Exchange Group Equivalent Product of 0.1 Proton Conductive Block Copolymer of the Present Invention is Proton Conductivity (26% RH, 80 ° C.) and Ion Exchange Group Equivalent The product of is a 0.1 or more, and contains the block which has a proton acid group. Here, the proton conductivity is measured under the conditions of 26% RH and 80 ° C., preferably 6.67E-05 to 5.00E-04 [S / cm], and more preferably 1.00E-04 to 3 .33E-04 [S / cm]. The ion exchange group equivalent is defined by the resin weight per mole of proton acid groups, and means the reciprocal of the number of moles of proton acid groups per unit weight of the resin, preferably 200 to 1500 g / mol, More preferably, it is 1000 g / mol. The product of the proton conductivity (26% RH, 80 ° C.) and the ion exchange group equivalent represents the ratio that contributes to the proton conductivity per proton acid group in the proton conductive block copolymer. .1 or more is preferable, and 0.14 or more is more preferable. When the product of proton conductivity (26% RH, 80 ° C.) and ion exchange group equivalent is 0.1 or more, sufficient proton conductivity can be exhibited while suppressing water absorption expansion. If it is less than 0.1, in order to exhibit sufficient proton conductivity, the ion exchange group equivalent must be made smaller, and if the ion exchange group equivalent is made small, the amount of proton acid groups becomes too large. Increases water absorption. High water absorption is not preferable because it causes water expansion. In addition, the fact that the ratio contributing to the proton conductivity per proton acid group is high indicates that the proton conductivity can be exhibited even under low humidification, and it can be used without problem even in PEFC operated under low humidification. can do.

  The proton conductive block copolymer of the present invention contains a block having a proton acid group. The block having a proton acid group is a hydrophilic block and exhibits high proton conductivity when absorbed. Even if the block having a proton acid group expands due to water absorption, the portion having no proton acid group suppresses it. Furthermore, since the block having a proton acid group and the block not having a proton acid group are bonded by the same molecule, absorption expansion of the block having a proton acid group can be suppressed without phase separation. As a result, a proton conductive membrane using such a proton conductive block copolymer has excellent water resistance while having high proton conductivity. Moreover, since the phase interface of two blocks is couple | bonded with the same molecule | numerator, generation | occurrence | production of the crack by the phase interface by the difference in expansion / contraction by the change of temperature or humidity is suppressed.

The proton conductive block copolymer of the present invention repeatedly has a block having a proton acid group. Specific examples of the proton acid group include sulfonic acid groups, carboxylic acid groups, and phosphonic acid groups represented by the following formulas (7) to (9). Among them, a sulfonic acid group represented by the following formula (7) is preferable, and a sulfonic acid group represented by Z = H in the following formula (7) is particularly preferable.
_{-C n H 2n -SO 3 Z (} n is an integer of 0, Z is H, Na or K) (7)
-C _n H _2n -COOZ _(n is an integer of 0, Z is H, Na or K) (8)
_{-C n H 2n -PO 3 Z 2} (n is an integer of 0, Z is H, Na or K) (9)

  The proton conductive block copolymer of the present invention may be any compound as long as the product of proton conductivity and ion exchange group equivalent is 0.1 or more and has a block having a proton acid group repeatedly. good. For example, although the proton conductive block copolymer which consists of the block (A) and block (B) mentioned later is mentioned, it is not limited to this.

  The swelling ratio of the proton conductive block copolymer of the present invention is 10 to 100 wt%. Here, the swelling ratio can be determined from the volume ratio of the dried resin before and after immersion in pure water at 25 ° C. for 24 hours. The proton conductive block copolymer according to the present invention has a smaller water absorption expansion than a copolymer having an equivalent ion exchange group equivalent. Further, when the proton conductive block copolymer is a crosslinked proton conductive block copolymer, the water absorption expansion is further smaller than that of a copolymer having no crosslinking group.

[式（１）中、Ａ_１は直接結合，−ＳＯ_２−または−ＣＯ−であり、式（１）中の芳香環の水素原子は、−Ｃ_ｍＨ_２ｍ＋１（ｍは１〜１０の整数）、−Ｆ、−ＣＦ_３、−Ｓｉ（ＣＨ_３）_３、−ＯＳｉ（ＣＨ_３）_３または−ＣＮに置換されていても良い。
式（２）中、Ｒ_１はプロトン酸基である。式（２）中、Ｂ_１は−ＳＯ_２−または−ＣＯ−であり、式（２）中の芳香環の水素原子は、プロトン酸基に置換されていても良い。
Ｘ_１及びＹ_１は式（３）〜（５）のいずれかであり、且つ、の少なくとも１つは式（４）あるいは（５）で表されるナフタレン環構造であり、（３）、（４）および（５）で表されるＹ_１の芳香環の水素原子はプロトン酸基に置換されていても良い。
式（３）中、のＤ_１およびＤ_２はそれぞれ独立して直接結合，−ＣＨ_２−、−Ｃ（ＣＨ_３）_２−、−Ｃ（ＣＦ_３）_２−、−Ｏ−、−ＳＯ_２−または−ＣＯ−であり、aおよびｂはそれぞれ独立して０または１を示す。
式（３）、（４）および（５）中の芳香族環の水素原子は−Ｃ_ｍＨ_２ｍ＋１（ｍは１〜１０の整数）、−Ｆ、−ＣＦ_３、−Ｓｉ（ＣＨ_３）_３、−ＯＳｉ（ＣＨ_３）_３または−ＣＮに置換されていても良い。 Block (A) and Block (B)
The block (A) having a specific structural unit having excellent water resistance and small water absorption expansion and the block (B) having a proton acid group according to the proton conductive block copolymer of the present invention are not particularly limited. The block (A) preferably has a structural unit represented by the following general formula (1), and the block (B) preferably has a structural unit represented by the following general formula (2).

[In the formula (1), A ₁ is a direct bond, —SO ₂ — or —CO—, and the hydrogen atom of the aromatic ring in the formula (1) is —C _m H _{2m + 1} (m is an integer of 1 to 10 ), -F, -CF ₃ , -Si (CH ₃ ) ₃ , -OSi (CH ₃ ) ₃ or -CN.
In formula (2), R ₁ is a protonic acid group. In Formula (2), B ₁ is —SO ₂ — or —CO—, and the hydrogen atom of the aromatic ring in Formula (2) may be substituted with a proton acid group.
X ₁ and Y ₁ are any _one of formulas (3) to (5), and at least one of them is a naphthalene ring structure represented by formula (4) or (5), and (3), ( The hydrogen atom of the aromatic ring of Y ₁ represented by 4) and (5) may be substituted with a proton acid group.
In formula (3), D ₁ and D ₂ are each independently a direct bond, —CH ₂ —, —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ —, —O—, —SO _2. -Or -CO-, and a and b each independently represent 0 or 1.
Equation (3), (4) and a hydrogen atom of the aromatic ring in (5) is _-C m _{H 2m +} 1 (m is an integer of from 1 to _10), - F, -CF 3, -Si _{(CH 3) 3} , —OSi (CH ₃ ) ₃ or —CN may be substituted.

  The preferred block (A) or block (B) according to the present invention has a naphthalene ring structure with excellent orientation in at least one of the blocks. Therefore, when a proton conductive membrane is formed using the proton conductive block copolymer of the present invention, when a hydrophobic block (A) having no proton acid group has a naphthalene ring, packing with a naphthalene ring is performed. Becomes better, it exhibits more hydrophobic property and water absorption expansion becomes smaller. On the other hand, when the hydrophilic block (B) having a proton acid group has a naphthalene ring, the proton acid group is easily assembled or arranged due to the orientation of the naphthalene ring. This is preferable because it is easy to move.

  Since the preferred block (A) and block (B) according to the present invention are composed of an aromatic polyether structure, a linking group, heat resistance, and radical resistance that are susceptible to hydrolysis of hot water, acid, alkali, alcohol, etc. Since it does not have a group having low properties, it is preferable because it hardly deteriorates or denatures when used in a fuel cell. On the other hand, block (A) or block (B) is susceptible to hydrolysis by hot water, acids, alkalis, alcohols, etc., ester bonds, carbonate bonds, amide bonds, imide bonds, low heat resistance, and radical attack. When an alkylene bond having an α-hydrogen, an aliphatic ether bond, or the like, which is easy to use, is deteriorated when used in a fuel cell, it is not preferable.

The molecular weight of the block (A) according to the present invention is not particularly limited and can be any molecular weight.
The hydrophobic block according to the present invention may be composed of a plurality of types of repeating structural units other than the block (A), but the hydrophobic block is susceptible to expansion due to hydrolysis or water absorption, amide bond, imide When it contains a bond or a protonic acid group, the solubility of the block copolymer in water and water absorption may be increased, which is not preferable.

  The molecular weight of the block (B) according to the present invention is preferably 0.05 to 0.5 dl / g, preferably 0.1 to 0.4 dl / g, in terms of reduced viscosity (concentration 0.5 g / dl, measured at 35 ° C.). Is more preferable, and 0.15-0.3 dl / g is particularly preferable. When the molecular weight of the block is too small, the block (B) and the block (A) are not separated from each other to form a single phase, which may reduce water resistance or increase water absorption. Absent. When the molecular weight of the block is too large, the hydrophobic block and the hydrophilic block are difficult to form a fine phase separation structure, and some of the molecular chains are formed only from blocks having a proton acid group. There is a possibility that the chain may be eluted in water, which is not preferable.

  The block (B) according to the present invention may have a plurality of types of repeating structural units in addition to the structural unit, and they may not contain a protonic acid group. In this case, the content of the repeating structural unit having a protonic acid group is preferably 100 to 30 mol%, particularly preferably 100 to 50 mol%, based on the entire block (B). When the content of the repeating structural unit (B) having a proton acid group is small, the proton conductivity is too low, which is not preferable.

Specific examples of the proton acid group contained in the block (B) according to the present invention include sulfonic acid groups, carboxylic acid groups, and phosphonic acid groups represented by the following formulas (7) to (9). Among them, a sulfonic acid group represented by the following formula (7) is preferable, and a sulfonic acid group represented by Z = H in the following formula (7) is particularly preferable.
_{-C n H 2n -SO 3 Z (} n is an integer of 0, Z is H, Na or K) (7)
-C _n H _2n -COOZ _(n is an integer of 0, Z is H, Na or K) (8)
_{-C n H 2n -PO 3 Z 2} (n is an integer of 0, Z is H, Na or K) (9)

When the protonic acid group is bonded to an aromatic ring directly bonded to —SO ₂ — or —CO— which is an electron withdrawing group, the protonic acid group has a stronger binding force than a protonic acid group bonded to another aromatic ring, and is decomposed. It is more preferable because it is less susceptible to dissociation. Among them, it is particularly preferable that the proton acid group is bonded to the aromatic ring to which —CO— is directly bonded.
In addition, when an existing aromatic polyether is sulfonated with fuming sulfuric acid or the like, a sulfonic acid group must be introduced into an aromatic ring to which —SO ₂ — or —CO— which is an electron withdrawing group is not directly bonded. It has been known.

[式（６）中の芳香環の水素原子が−Ｃ_ｍＨ_２ｍ＋１（ｍは１〜１０の整数）、−Ｆ、−ＣＦ_３、−Ｓｉ（ＣＨ_３）_３、−ＯＳｉ（ＣＨ_３）_３または−ＣＮに置換されていても良い。]
If the block (A) or the block (B) according to the present invention has a carbonyl group and an alkyl group directly bonded to an aromatic ring, it can be crosslinked at this portion, and the proton conductive block copolymer is crosslinked. Type proton conductive block copolymer. In this case, the proton conductive block copolymer is excellent in water resistance and has a small water absorption expansion, so that the membrane is not swelled or reduced in strength when used as a proton conductive membrane. Specifically, a _{B 1 A 1} and block of the block (A) (B) is -CO-, and the formula (3) hydrogen atoms of the aromatic ring of _{X 1} or _{Y 1} which is expressed by - It is the following formula (6) substituted by C _m H _{2m + 1} (m is an integer of 1 to 10), and _one of X ₁ and Y ₁ is a naphthalene ring structure represented by formulas (4) and (5) And the other is the formula (6).

Expression _-C hydrogen atom of the aromatic ring in _{(6) m H 2m + 1} (m is an integer of from 1 to _{10), - F, -CF 3,} -Si (CH 3) 3, -OSi (CH 3) 3 Alternatively, it may be substituted with -CN. ]

Proton Conductive Block Copolymer The proton conductive block copolymer of the present invention comprises a block (B) responsible for proton conduction having a proton acid group and a block (A) having excellent water resistance and small water absorption expansion. The block (B) responsible for proton conduction is easy to dissolve or absorb water and expand in water, and the block (A) has excellent water resistance and small water absorption and expansion, so even if trying to dissolve or absorb water in the block (B) Block (A) suppresses this. When the proton conductive block copolymer of the present invention is used for, for example, a proton conductive membrane, the block (A) and the block (B) are appropriately phase-separated. Since the interface between the two phases is bonded by the same molecule, even if the phase consisting of the block (B) is dissolved or absorbs water, the block (A) is excellent in water resistance and has a small water absorption expansion and is crosslinked. The phase suppresses this. As a result, the proton conducting membrane has a high proton acid group content and high water conductivity while having high proton conductivity. Further, since the two phase interfaces are bonded by the same molecule, the difference in expansion and contraction between the two phases due to changes in temperature and humidity is suppressed, and the generation of cracks due to the difference in expansion and contraction is suppressed.

  The swelling ratio of the proton conductive block copolymer of the present invention is 10 to 100 wt%. Here, the swelling ratio can be determined from the volume ratio of the dried resin before and after immersion in pure water at 25 ° C. for 24 hours. The proton conductive block copolymer according to the present invention has a smaller water absorption expansion than a copolymer having an equivalent ion exchange group equivalent. Further, when the proton conductive block copolymer is a crosslinked proton conductive block copolymer, the water absorption expansion is further smaller than that of a copolymer having no crosslinking group.

When the proton conductive coblock polymer is a random copolymer, the hydrophilic portion and the hydrophobic portion do not phase-separate and form a single phase. Therefore, when the composition of repeating structural units responsible for proton conduction increases, Solubility in water and water absorption expansion occur, and high proton conductivity and water resistance cannot be achieved at the same time.
In addition, a composite membrane composed of a proton conductive block copolymer and a resin having excellent water resistance and low water absorption expansion is difficult to form a fine phase separation structure because the polarities of the two resins are extremely different. There is a problem that the dissolution of the proton conductive resin in water and the water absorption expansion cannot be suppressed because they are not bonded by a chain, and the phase interface cracks due to the difference in expansion and contraction of the two phases due to changes in temperature and humidity. It is not preferable.

  The molecular weight of the proton conductive block copolymer of the present invention is not particularly limited, but a reduced viscosity (concentration of 0.5 g / dl, measured at 35 ° C.) is preferably in the range of 0.4 to 2.0 dl / g. A range of 0.5 to 1.5 dl / g is particularly preferred. If the molecular weight is too low, the resin strength is low, and the resulting film may crack due to shrinkage / expansion during drying and moisture absorption. On the other hand, if the molecular weight is too high, the solvent solubility of the resin becomes insufficient, which may cause problems in film formation.

  In the proton conductive block copolymer of the present invention, the product of proton conductivity and ion exchange group equivalent is preferably 0.1 or more, and more preferably 0.14 or more. The proton conductivity is a value measured at 26% RH and 80 ° C., preferably 6.67E-05 to 5.00E-04 [S / cm], more preferably 1.00E-04 to 3.33E. -04 [S / cm].

  In the proton conductive block copolymer of the present invention, the ratio of the block (B) having a proton acid group and the block (A) having hydrophobicity is not particularly limited, but ion exchange of the proton conductive block copolymer is not limited. The group equivalent is preferably 200 to 1500 g / mol, and particularly preferably 300 to 1000 g / mol. Here, the ion exchange group equivalent is defined by the resin weight per mole of proton acid groups and means the reciprocal of the number of moles of proton acid groups per resin unit weight. That is, the smaller the ion exchange group equivalent, the higher the proportion of the block (B) having a proton acid group, and the larger the ion exchange group equivalent, the lower the proportion of the block (B) having a proton acid group. If the ion exchange group equivalent is too small, the proportion of the block (A) is too small, and the water resistance of the proton conductive block copolymer may be insufficient. When the ion exchange group equivalent is too large, the ratio of the block having a proton acid group is too small, and thus sufficient proton conductivity may not be obtained.

Cross-linked proton-conductive block copolymer The proton-conductive block copolymer of the present invention is not derived from a proton acid group and can be cross-linked without generating a leaving component. A copolymer is preferred. This cross-linking does not use protonic acid groups for bonding polymer chains, in other words, a group or chain that bonds the polymer chains after crosslinking is not a group or chain derived from a protonic acid group. Cross-linked. That is, in the cross-linking not derived from the protonic acid group of the present invention, the cross-linking in which the protonic acid group chemically reacts during the cross-linking reaction, as well as the cross-linking in which the cross-linking group is introduced in advance through the protonic acid group and then cross-linked Is not included.

In the crosslinked proton conductive block copolymer of the present invention, the block (A) and the block (B) have a carbonyl group and an alkyl group directly bonded to an aromatic ring, and can be crosslinked at this portion. . Crosslinking allows the proton-conductive block copolymer chains to be bonded to each other, so the water resistance is excellent and the water absorption expansion is small, so that the membrane may swell or decrease in strength when used as a proton-conductive membrane. Since there is no, it is preferable. Especially, it is desirable that the alkyl group directly bonded to the aromatic ring is an alkyl group having 1 to 10 carbon atoms. Specifically, a _{B 1 A 1} and block of the block (A) (B) is -CO-, and the formula (3) hydrogen atoms of the aromatic ring of _{X 1} or _{Y 1} which is expressed by - A naphthalene ring structure which is the following formula (6) substituted with C _m H _{2m + 1} (n is an integer of 1 to 10), and any _one of X ₁ and Y ₁ is represented by formula (4) or (5) And the other is a cross-linked proton conductive block copolymer of the formula (6).

[式（６）中の芳香環の水素原子が−Ｃ_ｍＨ_２ｍ＋１（ｍは１〜１０の整数）、−Ｆ、−ＣＦ_３、−Ｓｉ（ＣＨ_３）_３、−ＯＳｉ（ＣＨ_３）_３または−ＣＮに置換されていても良い。]
この場合、前記一般式（２）のプロトン酸基は、電子吸引基である−ＣＯ−に直接結合した芳香環に結合しており、他の芳香環に結合したプロトン酸基に比べ結合力が強く、分解、解離を受けにくいため、特に好ましい。

Expression _-C hydrogen atom of the aromatic ring in _{(6) m H 2m + 1} (m is an integer of from 1 to _{10), - F, -CF 3,} -Si (CH 3) 3, -OSi (CH 3) 3 Alternatively, it may be substituted with -CN. ]
In this case, the protonic acid group of the general formula (2) is bonded to the aromatic ring directly bonded to the electron-withdrawing group —CO—, and has a binding force compared to the protonic acid group bonded to the other aromatic ring. It is particularly preferable because it is strong and is difficult to be decomposed or dissociated.

The crosslinking according to the present invention is preferable because the crosslinking density of the resin can be controlled without decreasing the amount of proton acid groups of the resin (increasing the ion exchange group equivalent). On the other hand, cross-linking derived from protonic acid groups is not preferable because it is necessary to use more protonic acid groups in order to increase the crosslink density, and as a result, the ionic conductivity of the resulting resin is lowered.
The crosslinked proton conductive block copolymer of the present invention can contain one or more protonic acid groups, carbonyl groups, and alkyl groups simultaneously in one repeating unit constituting the copolymer, and is extremely high. Since a crosslinking density can be obtained, it is particularly preferable. Further, this crosslinking mechanism is particularly preferred because it does not contain hydrogen at the α-position of the tertiary carbon that is susceptible to radical attack in the bond formed by crosslinking.

The crosslinking mechanism between the carbonyl group according to the present invention and the alkyl group having 1 to 10 carbon atoms directly bonded to the aromatic ring will be described. It is presumed that the carbonyl group in the polymer and the alkyl group having 1 to 10 carbon atoms directly bonded to the aromatic ring in the polymer are involved in the crosslinking reaction in the following manner. The following reaction formula shows the case where the alkyl group is a methyl group.

  As shown in the above reaction formula, radicals are generated on benzophenone by supplying energy by ultraviolet irradiation or heat treatment, and this extracts hydrogen from the methyl group. Subsequently, it is presumed that cross-linking of the polymers is caused by reactions such as dimerization of benzyl radical, reaction of benzyl radical and alcoholic carbon radical coupling, and dimerization of alcoholic carbon radical.

  The form of the proton conductive block copolymer and the cross-linked proton conductive block copolymer of the present invention is not particularly limited, and can be obtained by applying a powder, a varnish dissolved or dispersed in a solvent, and applying and drying the varnish. It can have a form such as a membrane. When the proton conductive block copolymer is used as a varnish dissolved or dispersed in a solvent, the solvent is not particularly limited. For example, water, methanol, ethanol, 1-propanol, 2-propanol, butanol, etc. Alcohols, hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methyl chloride and methylene chloride, ethers such as dichloroethyl ether, 1,4-dioxane and tetrahydrofuran, fatty acids such as methyl acetate and ethyl acetate In addition to esters, acetone, methyl ethyl ketone and other ketones, aprotic polar solvents such as N, N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethyl carbonate, etc. alone or in combination Can be used.

Proton Conductive Block Copolymer and Crosslinked Proton Conductive Block Copolymer Production Method There are no particular restrictions on the method for producing the proton conductive block copolymer and crosslinkable proton conductive block copolymer of the present invention, A specific production method is exemplified below by taking an aromatic polyether structure as an example.

1. Aromatic dihydroxy compound and aromatic dihalide compound having proton acid group, aromatic dihalide compound and aromatic dihydroxy compound having proton acid group, or aromatic dihydroxy compound having proton acid group and aromatic dihydroxy compound having proton acid group The compound is subjected to condensation polymerization to synthesize a protonic acid group-containing oligomer having a repeating structural unit having a reduced viscosity at 35 ° C. of 0.05 to 0.4 dl / g. An aromatic dihydroxy compound and an aromatic dihalide compound are added to this and subjected to condensation polymerization to obtain a block copolymer.

2. Aromatic dihydroxy compound and aromatic dihalide compound having proton acid group, aromatic dihalide compound and aromatic dihydroxy compound having proton acid group, or aromatic dihydroxy compound having proton acid group and aromatic dihydroxy compound having proton acid group The compounds are each subjected to condensation polymerization to synthesize a protonic acid group-containing oligomer having a repeating structural unit having a reduced viscosity at 35 ° C. of 0.05 to 0.4 dl / g. Separately, an aromatic dihydroxy compound and an aromatic dihalide compound are respectively polycondensed to obtain a hydrophobic oligomer. The hydrophobic oligomer is added to the protonic acid group-containing oligomer and subjected to condensation polymerization to obtain a block copolymer.

  Here, although there is no restriction | limiting in particular in the monomers used in manufacture of the proton conductive block copolymer concerning this invention, A typical example is illustrated below.

  Examples of the aromatic dihalide compound include the above-mentioned formulas such as 4,4′-difluorobenzophenone, 3,3′-difluorobenzophenone, 4,4′-dichlorobenzophenone, 3,3′-dichlorobenzophenone, 4,4′-difluorodiphenyl. Sulfone, 4,4′-dichlorodiphenylsulfone, 1,4-difluorobenzene, 1,3-difluorobenzene, 2,6-dichlorobenzonitrile, 4,4′-difluorobiphenyl, 3,3′-dibromo-4, 4'-difluorobiphenyl, 4,4'-difluorodiphenylmethane, 4,4'-dichlorodiphenylmethane, 4,4'-difluorodiphenyl ether, 2,2-bis (4-fluorophenyl) propane, 2,2-bis (4 -Chlorophenyl) propane, α, α'-bis (4-fluoro Phenyl) -1,4-diisopropylbenzene, 3,3′-dimethyl-4,4′-difluorobenzophenone, 3,3′-diethyl-4,4′-difluorobenzophenone, 3,3 ′, 5,5′- Tetramethyl-4,4′-difluorobenzophenone, 3,3′-dimethyl-4,4′-dichlorobenzophenone, 3,3 ′, 4,4′-tetramethyl-5,5′-dichlorobenzophenone, 3,3 '-Dimethyl-4,4'-difluorodiphenylsulfone, 3,3'-dimethyl-4,4'-dichlorodiphenylsulfone, 2,5-difluorotoluene, 2,5-difluoroethylbenzene, 2,5-difluoro-p -Xylene etc. are mentioned, It can use individually or in mixture of 2 or more types.

  Examples of the formula (3) and (6) aromatic dihydroxy compound include hydroquinone, resorcin, catechol, 4,4′-dihydroxybiphenyl, 4,4′-dihydroxydiphenyl sulfide, 4,4′-dihydroxydiphenylmethane, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenyl sulfone, 4,4′-dihydroxybenzophenone, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) hexa Fluoropropane, 1,4-bis (4-hydroxyphenyl) benzene, α, α′-bis (4-hydroxyphenyl) -1,4-dimethylbenzene, α, α′-bis (4-hydroxyphenyl) -1 , 4-Diisopropylbenzene, α, α'-bis (4-hydride Xylphenyl) -1,3-diisopropylbenzene, 4,4′-dihydroxybenzophenone, 1,4-bis (4-hydroxybenzoyl) benzene, 3,3′-difluoro-4,4′-dihydrokibiphenyl, 2-methyl Hydroquinone, 2-ethylhydroquinone, 2-isopropylhydroquinone, 2-octylhydroquinone, 2,3-dimethylhydroquinone, 2,3-diethylhydroquinone, 2,5-dimethylhydroquinone, 2,5-diethylhydroquinone, 2,5-diisopropyl Hydroquinone, 2,6-dimethylhydroquinone, 2,3,5-trimethylhydroquinone, 2,3,5,6-tetramethylhydroquinone, 3,3′-dimethyl-4,4′-dihydroxybiphenyl, 3,3 ′, 5,5'-tetramethyl -4,4'-dihydroxybiphenyl, 3,3'-dimethyl-4,4'-dihydroxydiphenylmethane, 3,3 ', 5,5'-tetramethyl-4,4'-dihydroxydiphenylmethane, 3,3', 5,5′-tetraethyl-4,4′-dihydroxydiphenylmethane, 3,3′-dimethyl-4,4′-dihydroxydiphenyl ether, 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxydiphenyl ether 3,3′-dimethyl-4,4′-dihydroxydiphenyl sulfide, 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxydiphenyl sulfide, 3,3′-dimethyl-4,4 ′ -Dihydroxydiphenylsulfone, 3,3 ', 5,5'-tetramethyl-4,4'-dihydroxydiphenylsulfone, 2 2-bis (3-methyl-4-hydroxyphenyl) propane, 2,2-bis (3-ethyl-4-hydroxyphenyl) propane, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane , Α, α′-bis (3-methyl-4-hydroxyphenyl) -1,4-diisopropylbenzene, α, α′-bis (3,5-dimethyl-4-hydroxyphenyl) -1,4-diisopropylbenzene , Α, α′-bis (3-methyl-4-hydroxyphenyl) -1,3-diisopropylbenzene, α, α′-bis (3,5-dimethyl-4-hydroxyphenyl) -1,3-diisopropylbenzene These can be used alone or in combination of two or more.

  Examples of the aromatic dihydroxy compounds represented by the formulas (4) and (5) include 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1, Examples include 6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, and these may be used alone or in combination of two or more. Can do.

  Examples of the aromatic dihalide compound having a proton acid group include sulfonated products and alkylsulfonated products of the above-mentioned aromatic dihalide compounds, 2,5-dichlorobenzoic acid, 2,5-difluorobenzoic acid, and 5,5′-carbonyl. Bis (2-fluorobenzoic acid), 5,5′-sulfonylbis (2-fluorobenzoic acid), 2,5-dichlorophenylphosphonic acid, 5,5′-carbonylbis (2-fluorobenzenephosphonic acid) and alkalis thereof A metal salt etc. can be mentioned.

  Examples of the aromatic dihydroxy compound having a proton acid group include sulfonated products and alkylsulfonated products of the above aromatic dihydroxy compounds, 2,5-dihydroxybenzoic acid, 2,5-dihydroxyterephthalic acid, and 5,5′-methylene. Examples thereof include aromatic dihydroxy compounds having disalicylic acid, 5,5′-thiodisalicylic acid, 2,5-dihydroxyphenylphosphonic acid, and alkali metal salts thereof.

The aromatic dihalide compound and aromatic dihydroxy compound sulfonated product and alkyl sulfonated product are obtained by sulfonating the aromatic dihalide compound and the aromatic dihydroxy compound with a known sulfonating agent such as fuming sulfuric acid (Macromol. Chem. Phys., 199 , 1421 (1998)).

Proton-conductive block copolymer cross-linked product The proton-conductive block copolymer cross-linked product of the present invention is obtained by cross-linking the proton conductive block copolymer. Even if it is a bridge type, it does not need to be a bridge type. The proton conductive block copolymer crosslinked product of the present invention is a crosslinked product that is not derived from a protonic acid group, and is a crosslinked product that does not use a protonic acid group for bonding polymer chains, in other words, a polymer chain after crosslinking. A cross-linked product in which the group or chain that binds each other is not a group or chain derived from a proton acid group. Although various forms can be taken, the form which bridge | crosslinks a carbonyl group and an alkyl group mainly takes. In addition, it can confirm that the proton-conductive block copolymer takes a crosslinked body by the reduction | decrease in the absorption peak of a carbonyl group in IR measurement, or the difference in the solvent solubility before and behind bridge | crosslinking.

The crosslinking according to the present invention means that polymer chains are bonded to each other by a reaction that does not generate a leaving component. Here, the elimination component is, for example, a by-product which is generated in the reaction and is not bonded to the resin chain, such as a halogenated hydrocarbon or salt in the Friedel-Craft reaction, water, hydrogen halide or salt in the condensation reaction. Indicates. Crosslinking that does not generate a desorbing component according to the present invention does not cause denaturation or degradation of the electrode material due to the desorbing component, has a uniform crosslink density in the film thickness direction, is easy to thicken, and corrodes the manufacturing equipment. It is preferable because no gas is generated. On the other hand, the cross-linking that generates the desorbing component requires a desorbing component removal operation, the cross-linking density is different between the film surface and the inside of the film or the back surface of the film having different desorbing component removal efficiencies, and it is difficult to increase the film thickness. There are problems such as the formation of voids in the film and the corrosion of the electrode material and the manufacturing apparatus due to the desorbed acidic gas.

  Although various methods are known as the crosslinking method, the crosslinking composed of a carbonyl group and an alkyl group according to the present invention is a crosslinking not derived from a protonic acid group, and a protonic acid group is used for bonding polymer chains to each other. In other words, a group or chain that bonds polymer chains to each other after crosslinking is not a group or chain derived from a protonic acid group. That is, in the cross-linking not derived from the protonic acid group of the present invention, the cross-linking in which the protonic acid group chemically reacts during the cross-linking reaction, as well as the cross-linking in which the cross-linking group is introduced in advance through the protonic acid group and then cross-linked Is not included. The cross-linking as in the present invention is preferable because the cross-linking density of the resin can be controlled without decreasing the amount of proton acid groups of the resin (increasing the ion exchange group equivalent). On the other hand, cross-linking derived from protonic acid groups is not preferable because it is necessary to use more protonic acid groups in order to increase the cross-linking density, and as a result, the ionic conductivity of the resulting cross-linked resin decreases. .

Proton Conducting Membrane The proton conducting membrane of the present invention is a proton conducting membrane comprising the proton conducting block copolymer of the present invention and a type proton conducting block copolymer crosslinked product obtained by crosslinking the proton conducting block copolymer. Here, the proton conducting membrane of the present invention includes not only a self-supporting membrane but also a coating film in close contact with a substrate, an electrode membrane, other proton conducting membranes, and the like. Here, although there is no restriction | limiting in particular in the thickness of the proton conductive film | membrane of this invention, when it is a self-supporting film | membrane, it is preferable that it is 10-100 micrometers in the case of being a coating film.
The proton conductive membrane of the present invention only needs to contain the proton conductive block copolymer or cross-linked proton conductive block copolymer cross-linked product of the present invention, and is a conductive material having electrical conductivity, hydrogen oxidation reaction, oxygen It may be combined with a catalyst that promotes the reduction reaction.

As the conductive material, any conductive material may be used, and various metals, carbon materials, and the like can be used. Examples thereof include carbon black such as acetylene black, activated carbon, graphite and the like, and these are used alone or mixed and used in the form of powder or sheet.
The catalyst is not particularly limited as long as it promotes hydrogen oxidation reaction and oxygen reduction reaction. For example, lead, iron, manganese, cobalt, chromium, gallium, vanadium, tungsten, ruthenium, iridium, palladium, platinum, Rhodium or an alloy thereof.

Fuel Cell The proton conductive membrane of the present invention can be used as an electrolyte membrane of various known fuel cells, and as a fuel source of the fuel cell, for example, natural gas, hydrogen, alcohol such as methanol can be used. The fuel cell using the proton conducting membrane of the present invention is excellent in power generation efficiency and reliability, because it does not easily cause membrane degradation, resin elution, proton acid group elimination, or fuel crossover, resulting in a decrease in output.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not restrict | limited at all by this.
Test methods of various tests in the examples are as follows.
(I) Reduced viscosity (ηinh)
After 0.50 g of the proton conductive block copolymer or oligomer thereof was dissolved by heating in 100 ml of dimethylsulfoxide or N-methylpyrrolidone, it was measured with an Ubbelohde viscometer at 35 ° C.
(Ii) Ion exchange group equivalent (EW)
The proton conductive block copolymer or proton conductive membrane dried under vacuum at 100 ° C. was precisely weighed in a glass container that could be sealed, and an excess amount of sodium chloride aqueous solution was added thereto and stirred overnight. The hydrogen chloride generated in the system was titrated with a 0.01N sodium hydroxide standard aqueous solution using a phenolphthalein indicator and calculated.
(Iii) Swelling rate A proton conductive block copolymer or proton conductive membrane dried at 120 ° C. for 12 hours under nitrogen ventilation was immersed in pure water at 23 ° C. for 24 hours, and the volume change was calculated.
(Iv) Proton conductivity A proton conducting membrane is cut out as a sample to a width of 5 mm and a length of 40 mm, then placed on a PTFE holder, four electrodes are pressed, and an arc obtained by the AC impedance method of the 4-terminal method is used. The resistivity was measured. The distance between the voltage terminals was 20 mm. For the measurement of impedance, an LCR meter (manufactured by Hioki Electric Co., Ltd., 3532) was used. The temperature was controlled at 80 ° C. by placing the sample connected with the electrode in a thermostat made of aluminum block. Humidification is performed by introducing steam into a constant temperature thermostat, heating distilled water to a constant temperature with a steam generator, and using the generated steam, the humidity in the thermostat is 26% RH or 65% RH. The conductivity was measured by setting it to be constant. Humidity was measured with a Rotronic dew point meter. The film thickness was measured using a micrometer in a dry state.
(V) Methanol permeability Distilled water and a 1 mol / L aqueous methanol solution were brought into contact with each other through a proton conductive membrane having a diameter of 23 mmφ at room temperature, and the change in methanol concentration on the distilled water side up to 3 hours was measured by gas chromatography. The methanol permeation rate at a film thickness of 50 μm was calculated from the slope of the obtained methanol concentration increasing line, and this was defined as methanol permeability.

Example 1
To a flask equipped with a nitrogen inlet tube, a thermometer, a separator filled with toluene, and a stirrer, 6.7756 g (0,3,3′-carbonylbis (6-fluorobenzenesulfonic acid sodium salt)) 0.016 mol), 3.2034 g (0.020 mol) of 1,4-dihydroxynaphthalene and 2.65 g (0.019 mol) of anhydrous potassium carbonate were precisely weighed. To this, 40.0 g of dimethyl sulfoxide (hereinafter abbreviated as DMSO) and 16.0 g of toluene were added, and the temperature was raised to 140 ° C. with stirring through nitrogen gas, followed by reaction for 7.5 hours. The reaction was performed under toluene return distillation, and the distilled water was separated and collected by a separator. After cooling, a part of the reaction mass was sampled, diluted with DMSO, the supernatant was discharged into methanol, the oligomer was precipitated, washed with acetone, and then dried at 150 ° C. for 4 hours under nitrogen flow to obtain the oligomer. The obtained oligomer was a compound containing a protonic acid group (sodium sulfonate group) directly bonded to an aromatic ring and a naphthalene ring structure, and its reduced viscosity was 0.19 dl / g (DMSO).

  To the reaction mass, 7.4188 g (0.034 mol) of 4,4′-difluorobenzophenone, 7.6905 g (0.041 mol) of 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxydiphenylmethane, Anhydrous potassium carbonate (5.63 g, 0.041 mol), DMSO (60.0 g), and toluene (24.0 g) were added, and the mixture was heated to 140 ° C. with stirring through nitrogen gas. The reaction was continued for 3.5 hours.

The obtained viscous reaction mass (110 ° C.) was discharged into 1.5 L of acetone using a homomixer, and the precipitated polymer was collected by filtration, twice with 2 L of distilled water and once with 2 L of acetone for 1 hour. Each sludge was collected by filtration. It was dried at 50 ° C. for 8 hours and at 150 ° C. for 4 hours (both in a nitrogen atmosphere) to obtain a crosslinked proton-conductive block copolymer having a proton acid group (sodium sulfonate group). The obtained block copolymer was 22.4 g (yield 90.0%), and the reduced viscosity (ηinh) was 0.6 dl / g (N-methylpyrrolidone).
4 g of the obtained block copolymer was dissolved in 12.0 g of N-methylpyrrolidone to obtain a varnish having a polymer concentration of 25%. The obtained varnish was cast on a glass substrate using a blade having a spacer, heated from room temperature to 200 ° C. under nitrogen flow over 2 hours, and then held and dried at 200 ° C. for 4 hours to obtain a film having a thickness of 50 μm. Obtained.
The obtained film was peeled off from the glass substrate and cross-linked by irradiation with light of 500 mJ / cm 2 on both sides using a metal halide lamp to obtain a film-like proton conductive block copolymer cross-linked product.
This crosslinked film was immersed in a 2N aqueous sulfuric acid solution and distilled water for 1 day to perform proton exchange of sodium sulfonate groups, thereby obtaining a film having free sulfonic acid groups.
The film obtained had an ion exchange group equivalent (EW) of 799 g / mol, a swelling rate of 20%, a proton conductivity of 2.14E-04S / cm at 26% RH, and 2.77E-02S / cm at 65% RH. Met. The methanol permeability was 0.5 μmol / cm2 / min.

(Example 2)
Into a flask equipped with a nitrogen inlet tube, a thermometer, a separator equipped with a separator filled with toluene, and a stirrer, 13.5133 g (0,3,3′-carbonylbis (sodium 6-fluorobenzenesulfonate)) 0.032 mol), 1,6-dihydroxynaphthalene (6.4068 g, 0.040 mol) and anhydrous potassium carbonate (5.30 g, 0.038 mol) were precisely weighed. To this, 80.0 g of dimethyl sulfoxide and 32.0 g of toluene were added, and the temperature was raised to 140 ° C. while stirring through nitrogen gas, followed by reaction for 8 hours. The reaction was performed under toluene return distillation, and the distilled water was separated and collected by a separator. After cooling, a part of the reaction mass was sampled, diluted with DMSO, the supernatant was discharged into methanol, the oligomer was precipitated, washed with acetone, and then dried at 150 ° C. for 4 hours under nitrogen flow to obtain the oligomer. The obtained oligomer was a compound containing a protonic acid group (sodium sulfonate group) directly bonded to an aromatic ring and a naphthalene ring structure, and the reduced viscosity of the oligomer was 0.21 dl / g (DMSO).

  In the reaction mass, 4,4′-difluorobenzophenone 14.8376 g (0.068 mol), 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxydiphenylmethane 15.3810 g (0.060 mol), 11.26 g (0.082 mol) of anhydrous potassium carbonate, 121.0 g of DMSO and 48.0 g of toluene were added, the temperature was raised to 140 ° C. with stirring through nitrogen gas, and then the temperature was increased to 140 ° C. for 7 hours. The reaction was continued for 2 hours.

The obtained viscous reaction mass (110 ° C.) was discharged into 3 L of acetone using a homomixer, and the precipitated polymer was collected by filtration, twice with 4 L of distilled water and once with 4 L of acetone, each for 1 hour each. And then collected by filtration. It was dried at 50 ° C. for 8 hours and at 150 ° C. for 4 hours (both in a nitrogen atmosphere) to obtain a crosslinked proton-conductive block copolymer having a proton acid group (sodium sulfonate group). The obtained block copolymer was 46.2 g (yield 92.8%), and the reduced viscosity was 1.00 dl / g (N-methylpyrrolidone).
4 g of the obtained block copolymer was dissolved in 16.0 g of N-methylpyrrolidone to obtain a varnish having a polymer concentration of 20%. The obtained varnish was cast on a glass substrate using a blade having a spacer, heated from room temperature to 200 ° C. under nitrogen flow over 2 hours, and then held and dried at 200 ° C. for 4 hours to obtain a film having a thickness of 50 μm. Obtained.
The obtained film was peeled off from the glass substrate and cross-linked by irradiation with light of 500 mJ / cm 2 on both sides using a metal halide lamp to obtain a film-like proton conductive block copolymer cross-linked product.
This crosslinked film was immersed in a 2N aqueous sulfuric acid solution and distilled water for 1 day to perform proton exchange of sodium sulfonate groups, thereby obtaining a film having free sulfonic acid groups.
The film obtained had an ion exchange group equivalent of 752 g / mol, a swelling rate of 31%, a proton conductivity of 2.35E-04S / cm at 26% RH and 2.82E-02S / cm at 65% RH. . The methanol permeability was 0.6 μmol / cm2 / min.

(Example 3)
Into a flask equipped with a nitrogen inlet tube, a thermometer, a separator equipped with a separator filled with toluene, and a stirrer, 13.5133 g (0,3,3′-carbonylbis (sodium 6-fluorobenzenesulfonate)) 0.032 mol), 2,7-dihydroxynaphthalene 6.4068 g (0.040 mol) and 5.300 g (0.038 mol) anhydrous potassium carbonate were precisely weighed. DMSO 80.0g and toluene 32.0g were added to this, and it heated up to 140 degreeC, stirring for 4 hours, and reacted for 4 hours. The reaction was performed under toluene return distillation, and the distilled water was separated and collected by a separator. After cooling, a part of the reaction mass was sampled, diluted with DMSO, the supernatant was discharged into methanol, the oligomer was precipitated, washed with acetone, and then dried at 150 ° C. for 4 hours under nitrogen flow to obtain the oligomer. The obtained oligomer was a compound containing a protonic acid group (sodium sulfonate group) directly bonded to an aromatic ring and a naphthalene ring structure, and the reduced viscosity of the oligomer was 0.20 dl / g (DMSO).

  In the reaction mass, 4,4′-difluorobenzophenone 14.8376 g (0.068 mol), 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxydiphenylmethane 15.3810 g (0.060 mol), Anhydrous potassium carbonate (11.20 g, 0.081 mol), DMSO (120.0 g) and toluene (48.0 g) were added, and the mixture was heated to 140 ° C. with stirring through nitrogen gas. After 6 hours and 30 minutes, toluene was further distilled off. The temperature was raised to 160 ° C. and the reaction was performed for 2 hours.

The obtained viscous reaction mass (110 ° C.) was discharged into 3 L of acetone using a homomixer, and the precipitated polymer was collected by filtration, twice with 4 L of distilled water and once with 4 L of acetone, each for 1 hour each. And then collected by filtration. It was dried at 50 ° C. for 8 hours and at 150 ° C. for 4 hours (both in a nitrogen atmosphere) to obtain a crosslinked proton-conductive block copolymer having a proton acid group (sodium sulfonate group). The obtained block copolymer was 46.7 g (yield 93.8%), and the reduced viscosity was 1.45 dl / g (N-methylpyrrolidone).
4 g of the obtained block copolymer was dissolved by heating in 21.0 g of N-methylpyrrolidone to obtain a varnish having a polymer concentration of 16%. The obtained varnish was cast on a glass substrate using a blade having a spacer, heated from room temperature to 200 ° C. under nitrogen flow over 2 hours, and then held and dried at 200 ° C. for 4 hours to obtain a film having a thickness of 50 μm. Obtained.
The obtained film was peeled off from the glass substrate and cross-linked by irradiation with light of 500 mJ / cm 2 on both sides using a metal halide lamp to obtain a film-like proton conductive block copolymer cross-linked product.
This crosslinked film was immersed in a 2N aqueous sulfuric acid solution and distilled water for 1 day to perform proton exchange of sodium sulfonate groups, thereby obtaining a film having free sulfonic acid groups.
The film obtained had an ion exchange group equivalent of 796 g / mol, a swelling rate of 25%, a proton conductivity of 1.83E-04S / cm at 26% RH, and 2.31E-02S / cm at 65% RH. . The methanol permeability was 0.5 μmol / cm2 / min.

Example 4
Into a flask equipped with a nitrogen inlet tube, a thermometer, a cooler equipped with a separator filled with toluene, and a stirrer, 22.3814 g (0,3,6'-sodium 6-fluorobenzenesulfonate) 0.053 mol), 10.4-113 g (0.06625 mol) of 1,4-dihydroxynaphthalene and 8.78 g (0.064 mol) of anhydrous potassium carbonate were precisely weighed. To this, 132.0 g of DMSO and 53.0 g of toluene were added, and the mixture was heated to 140 ° C. while stirring through nitrogen gas, and then reacted for 9 hours. The reaction was performed under toluene return distillation, and the distilled water was separated and collected by a separator. After cooling, a part of the reaction mass was sampled, diluted with DMSO, the supernatant was discharged into methanol, the oligomer was precipitated, washed with acetone, and then dried at 150 ° C. for 4 hours under nitrogen flow to obtain the oligomer. The obtained oligomer was a compound containing a protonic acid group (sodium sulfonate group) directly bonded to an aromatic ring and a naphthalene ring structure, and the reduced viscosity of the oligomer was 0.17 dl / g (DMSO).

  To the reaction mass, 10.4554 g (0.047 mol) of 4,4′-difluorobenzophenone, 8.6518 g (0.03375 mol) of 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxydiphenylmethane, Anhydrous potassium carbonate (7.78 g, 0.056 mol), DMSO (76.0 g) and toluene (30.0 g) were added, and the mixture was heated to 140 ° C. with stirring through nitrogen gas. The temperature was raised to 4 hours and 30 minutes.

The obtained viscous reaction mass (110 ° C.) was discharged into 3 L of acetone using a homomixer, and the precipitated polymer was collected by filtration, twice with 4 L of distilled water and once with 4 L of acetone, each for 1 hour each. And then collected by filtration. It was dried at 50 ° C. for 8 hours and at 150 ° C. for 4 hours (both in a nitrogen atmosphere) to obtain a crosslinked proton-conductive block copolymer having a proton acid group (sodium sulfonate group). The obtained block copolymer was 48.2 g (yield 93.6%), and the reduced viscosity was 0.56 dl / g (N-methylpyrrolidone).
4 g of the obtained block copolymer was dissolved in 8.5 g of N-methylpyrrolidone to obtain a varnish having a polymer concentration of 32%. The obtained varnish was cast on a glass substrate using a blade having a spacer, heated from room temperature to 200 ° C. under nitrogen flow over 2 hours, and then held and dried at 200 ° C. for 4 hours to obtain a film having a thickness of 50 μm. Obtained.
The obtained film was peeled off from the glass substrate and cross-linked by irradiation with light of 500 mJ / cm 2 on both sides using a metal halide lamp to obtain a film-like proton conductive block copolymer cross-linked product.
This crosslinked film was immersed in a 2N aqueous sulfuric acid solution and distilled water for 1 day to perform proton exchange of sodium sulfonate groups, thereby obtaining a film having free sulfonic acid groups.
The obtained film had an ion exchange group equivalent of 457 g / mol, a swelling rate of 76%, a proton conductivity of 9.99E-04S / cm at 26% RH, and 8.05E-02S / cm at 65% RH. . The methanol permeability was 1.3 μmol / cm2 / min.

(Example 5)
Into a flask equipped with a nitrogen inlet tube, a thermometer, a condenser equipped with a separator filled with toluene, and a stirrer, 23.2260 g (0,3,6'-sodium 6-fluorobenzenesulfonate) 0.055 mol), 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxydiphenylmethane (17.241 g, 0.06875 mol) and anhydrous potassium carbonate (9.11 g, 0.066 mol) were precisely weighed. DMSO (163.0 g) and toluene (65.0 g) were added thereto, and the mixture was heated to 140 ° C. with stirring through nitrogen gas, and then reacted for 9 minutes. The reaction was performed under toluene return distillation, and the distilled water was separated and collected by a separator. After cooling, a part of the reaction mass was sampled, diluted with DMSO, the supernatant was discharged into methanol, the oligomer was precipitated, washed with acetone, and then dried at 150 ° C. for 4 hours under nitrogen flow to obtain the oligomer. The obtained oligomer was a compound containing a proton acid group (sodium sulfonate group) directly bonded to an aromatic ring, and the reduced viscosity of the oligomer was 0.17 dl / g (DMSO).

  To the reaction mass, 9.8190 g (0.045 mol) of 4,4′-difluorobenzophenone, 5.0053 g (0.03125 mol) of 2,7-dihydroxynaphthalene, 7.45 g (0.054 mol) of anhydrous potassium carbonate, DMSO 59. 0 g and 24.0 g of toluene were added, the temperature was raised to 140 ° C. while stirring through nitrogen gas, and then the temperature was raised to 160 ° C. for 5 hours, and further toluene was distilled off, and the reaction was carried out for 12 hours.

The obtained viscous reaction mass (110 ° C.) was discharged into 3 L of acetone using a homomixer, and the precipitated polymer was collected by filtration, twice with 4 L of distilled water and once with 4 L of acetone, each for 1 hour each. And then collected by filtration. It was dried at 50 ° C. for 8 hours and at 150 ° C. for 4 hours (both in a nitrogen atmosphere) to obtain a crosslinked proton-conductive block copolymer having a proton acid group (sodium sulfonate group). The obtained block copolymer was 45.8 g (yield 84.7%), and the reduced viscosity was 1.12 dl / g (N-methylpyrrolidone).
4 g of the obtained block copolymer was dissolved by heating in 12.0 g of N-methylpyrrolidone to obtain a varnish having a polymer concentration of 25%. The obtained varnish was cast on a glass substrate using a blade having a spacer, heated from room temperature to 200 ° C. under nitrogen flow over 2 hours, and then held and dried at 200 ° C. for 4 hours to obtain a film having a thickness of 50 μm. Obtained.
The obtained film was peeled off from the glass substrate and cross-linked by irradiation with light of 500 mJ / cm 2 on both sides using a metal halide lamp to obtain a film-like proton conductive block copolymer cross-linked product.
This crosslinked film was immersed in a 2N aqueous sulfuric acid solution and distilled water for 1 day to perform proton exchange of sodium sulfonate groups, thereby obtaining a film having free sulfonic acid groups.
The film obtained had an ion exchange group equivalent of 453 g / mol, a swelling rate of 74%, a proton conductivity of 2.40E-04S / cm at 26% RH and 4.54E-02S / cm at 65% RH. . The methanol permeability was 1.1 μmol / cm2 / min.

(Comparative Example 1)
Into a flask equipped with a nitrogen inlet tube, a thermometer, a cooler equipped with a separator filled with toluene, and a stirrer, 147,802 g (0,3,3′-carbonylbis (6-fluorobenzenesulfonic acid sodium salt)) 0.035 mol), 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxydiphenylmethane, 11.153 g (0.043 mol), and 5.80 g (0.042 mol) of anhydrous potassium carbonate were precisely weighed. To this, 104.0 g of dimethyl sulfoxide and 42.0 g of toluene were added, the temperature was raised to 140 ° C. while stirring through nitrogen gas, and a reaction was carried out for 8 hours. The reaction was performed under toluene return distillation, and the distilled water was separated and collected by a separator. After cooling, a part of the reaction mass was sampled, diluted with DMSO, the supernatant was discharged into methanol, the oligomer was precipitated, washed with acetone, and then dried at 150 ° C. for 4 hours under nitrogen flow to obtain the oligomer. The obtained oligomer was a compound in which a protonic acid group and an alkyl group were directly bonded to an aromatic ring, and the reduced viscosity was 0.20 dl / g (DMSO).

  To the reaction mass, 14.4830 g (0.065 mol) of 4,4′-difluorobenzophenone, 14.4197 g (0.05625 mol) of 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxydiphenylmethane, Anhydrous potassium carbonate (10.76 g, 0.12 mol), DMSO (114.0 g), and toluene (46.0 g) were added, and the mixture was heated to 140 ° C. with stirring through nitrogen gas. The reaction was continued for 8 hours.

The obtained viscous reaction mass (110 ° C.) was discharged into 3 L of acetone using a homomixer, and the precipitated polymer was collected by filtration, twice with 4 L of distilled water and once with 4 L of acetone, each for 1 hour each. And then collected by filtration. It was dried at 50 ° C. for 8 hours and at 150 ° C. for 4 hours (both in a nitrogen atmosphere) to obtain 46.1 g (yield 91.1%) of a block copolymer having a proton acid group (sodium sulfonate group). .
The reduced viscosity of the obtained block copolymer was 1.10 dl / g (N-methylpyrrolidone).
4 g of the obtained block copolymer was dissolved by heating in 14.2 g of N-methylpyrrolidone to obtain a varnish having a polymer concentration of 22%. The obtained varnish was cast on a glass substrate using a blade having a spacer, heated from room temperature to 200 ° C. under nitrogen flow over 2 hours, and then held and dried at 200 ° C. for 4 hours to obtain a film having a thickness of 50 μm. Obtained.
The obtained film was peeled off from the glass substrate and cross-linked by irradiation with light of 500 mJ / cm 2 on both sides using a metal halide lamp.
This crosslinked film was immersed in a 2N aqueous sulfuric acid solution and distilled water for 1 day to perform proton exchange of sodium sulfonate groups, thereby obtaining a film having free sulfonic acid groups.
The ion exchange group equivalent of the obtained film was 761 g / mol, the swelling rate was 44%, the proton conductivity was 2.95E-05S / cm at 26% RH, and 9.41E-03 at 65% RH. The methanol permeability was 0.8 μmol / cm2 / min.

(Comparative Example 2)
To a flask equipped with a nitrogen inlet tube, a thermometer, a separator filled with toluene, and a stirrer, 3,3′-carbonylbis (sodium 6-fluorobenzenesulfonate)
25.3374 g (0.060 mol), 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxydiphenylmethane 17.0900 g (0.06667 mol) and anhydrous potassium carbonate 10.35 g (0.075 mol). Weighed precisely. Dimethyl sulfoxide (170.0 g) and toluene (68.0 g) were added thereto, and the mixture was heated to 140 ° C. with stirring through nitrogen gas, and then reacted for 11 hours. The reaction was performed under toluene return distillation, and the distilled water was separated and collected by a separator. After cooling, a part of the reaction mass was sampled, diluted with DMSO, the supernatant was discharged into methanol, the oligomer was precipitated, washed with acetone, and then dried at 150 ° C. for 4 hours under nitrogen flow to obtain the oligomer. The obtained oligomer was a compound in which a protonic acid group and an alkyl group were directly bonded to an aromatic ring, and the reduced viscosity was 0.25 dl / g (DMSO).

  To the reaction mass, 8.7280 g (0.040 mol) of 4,4′-difluorobenzophenone, 8.5450 g (0.03333 mol) of 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxydiphenylmethane, 6.90 g (0.050 mol) of anhydrous potassium carbonate, 69.0 g of DMSO and 28.0 g of toluene were added, the temperature was raised to 140 ° C. while stirring through nitrogen gas, and then 160 ° C. while distilling off toluene further for 9 hours. The temperature was raised to 7, and the reaction was carried out for 7 hours.

The obtained viscous reaction mass (110 ° C.) was discharged into 3 L of acetone using a homomixer, and the precipitated polymer was collected by filtration, twice with 4 L of distilled water and once with 4 L of acetone, each for 1 hour each. And then collected by filtration. It was dried at 50 ° C. for 8 hours and at 150 ° C. for 4 hours (both in a nitrogen atmosphere) to obtain 54.6 g (yield 92.1%) of a block copolymer having a protonic acid group (sodium sulfonate group). .
The reduced viscosity of the obtained block copolymer was 1.03 dl / g (N-methylpyrrolidone).
4 g of the obtained block copolymer was dissolved by heating in 16.0 g of N-methylpyrrolidone to obtain a varnish having a polymer concentration of 20%. The obtained varnish was cast on a glass substrate using a blade having a spacer, heated from room temperature to 200 ° C. under nitrogen flow over 2 hours, and then held and dried at 200 ° C. for 4 hours to obtain a film having a thickness of 50 μm. Obtained.
The obtained film was peeled off from the glass substrate and cross-linked by irradiation with light of 500 mJ / cm 2 on both sides using a metal halide lamp.
This crosslinked film was immersed in a 2N aqueous sulfuric acid solution and distilled water for 1 day to perform proton exchange of sodium sulfonate groups, thereby obtaining a film having free sulfonic acid groups.
The film obtained had an ion exchange group equivalent of 445 g / mol, a swelling rate of 86%, a proton conductivity of 2.04E-04S / cm at 26% RH, and 4.17E-05S / cm at 65% RH. . The methanol permeability was 1.7 μmol / cm2 / min.

From Table 1, the product values of proton conductivity (26% RH, 80 ° C.) and ion exchange group equivalent (EW = polymer molecular weight / protonic acid group amount) in Examples 1 to 5 are all 0.1 or more. It can be seen that it is higher than Comparative Examples 1 and 2. Further, when Examples 1 to 3 and Comparative Example 1 having close EW values, or Examples 4 to 6 and Comparative Example 2 were compared, in all of the Examples, the swelling rate was lowered, but under low humidification. It can be seen that the proton conductivity is improved. From this, it can be seen that by introducing a naphthalene ring structure, the proton conductivity can be improved while suppressing the swelling rate. Further, when Examples 1 to 3 and Comparative Example 1 or Examples 4 to 6 and Comparative Example 2 are compared, it can be seen that methanol permeability is reduced in all Examples.

Claims (8)

  The product of proton conductivity (26% RH, 80 ° C.) and ion exchange group equivalent (EW = polymer molecular weight / proton acid group amount) is 0.1 or more, and includes a block having a proton acid group Proton conductive block copolymer. The proton conductive block copolymer is characterized in that the block (A) has repeating structural units represented by the general formula (1) and the block (B) has repeating structural units represented by the general formula (2). Polymer.

[In the formula (1), A ₁ is a direct bond, —SO ₂ — or —CO—, and the hydrogen atom of the aromatic ring in the formula (1) is —C _m H _{2m + 1} (m is an integer of 1 to 10 ), -F, -CF ₃ , -Si (CH ₃ ) ₃ , -OSi (CH ₃ ) ₃ or -CN.
In formula (2), R ₁ is a protonic acid group. In Formula (2), B ₁ is —SO ₂ — or —CO—, and the hydrogen atom of the aromatic ring in Formula (2) may be substituted with a proton acid group.
X ₁ and Y ₁ are any one of formulas (3) to (5), and at least one of them is a naphthalene ring structure represented by formula (4) or (5), and the formula (3) , (4) and (5), the hydrogen atom of the aromatic ring of Y ₁ may be substituted with a proton acid group.
In formula (3), D ₁ and D ₂ are each independently a direct bond, —CH ₂ —, —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ —, —O—, —SO _2. -Or -CO-, and a and b each independently represent 0 or 1.
Equation (3), (4) and a hydrogen atom of the aromatic ring in (5) is _-C m _{H 2m +} 1 (m is an integer of from 1 to _10), - F, -CF 3, -Si _{(CH 3)} 3, -OSi _{(CH 3)} 3 or may be substituted to -CN. ] A _{1 of the} block (A) represented by the formula (1) and B _{1 of the} block (B) represented by the formula (2) are —CO— and X ₁ represented by the formula (3) or _-C hydrogen atom of an aromatic ring m _{H 2m +} 1 of _{Y 1} (m is an integer of from 1 to 10) and the following formula substituted with (6), either the expression of _{X 1} and _{Y 1} (4) The proton-conductive block copolymer according to claim 2, wherein the proton-conductive block copolymer is a cross-linked proton-conductive block copolymer represented by formula (6), wherein the other is a naphthalene ring structure represented by (5):

Expression _-C hydrogen atom of the aromatic ring in _{(6) m H 2m + 1} (m is an integer of from 1 to _{10), - F, -CF 3,} -Si (CH 3) 3, -OSi (CH 3) 3 Alternatively, it may be substituted with -CN. ]
The proton conductive block copolymer according to claim 2 or 3, wherein a of X ₁ or Y ₁ represented by the general formula (3) or the formula (6) of the block (A) and the block (B) is 0. Protonic acid _{group, -C n H 2n -SO 3 Z} , -C n H 2n -PO 3 Z 2, -C n H 2n -COOZ (n is an integer of 0, Z is H, with Na or K The proton-conductive block copolymer according to claim 1, wherein the proton-conductive block copolymer is any one of the above.   A proton conductive block copolymer crosslinked product obtained by crosslinking the proton conductive block copolymer according to claim 1.   A proton conducting membrane comprising the proton conducting block copolymer or the proton conducting block copolymer crosslinked product according to claim 1. A fuel cell comprising the proton conducting membrane according to claim 7.