Separator, curable composition, and method for producing separator

Abstract

The present invention provides: a separator which contains a crosslinked body that is obtained by a curing reaction of any one of (a) a compound represented by formula (I-1), (b) a combination of a compound represented by formula (I-2) and a polyfunctional epoxy or oxetane compound having no polyethyleneoxy group, (c) a compound represented by formula (II -1), and (d) a combination of a compound represented by formula (II -2) and a polyfunctional allyl compound having no polyethyleneoxy group, wherein the constituent component derived from a compound represented by each formula is 50% by mass or more; a curable composition; and a method for producing the separator. X1 and Y represent a group that has at least one of an epoxy group and an oxetanyl group. n represents a number equal to or greater than 2, X2 and X4 represent a hydrogen atom or a non-chain polymerizable organic group. X3 and Z represent a group having an allyl group.

Description

Separator, curable composition, and method for producing separator

[0001] The present invention relates to a separator, a curable composition suitable for producing the separator, and a method for producing the separator.

[0002] Hydrogen is a clean energy source that does not emit carbon dioxide and is used, for example, as fuel for fuel cell vehicles and household fuel cells. Water electrolysis (electrolysis) is a well-known method for producing hydrogen. Hydrogen can be produced without carbon dioxide emissions by electrolyzing water using renewable energy as power. Therefore, hydrogen is increasingly attracting attention as a fundamental energy source for a sustainable society.

[0003] Alkaline water electrolysis (AWE), which uses a highly concentrated alkaline aqueous solution as the electrolyte, is a known practical water electrolysis technology. In alkaline water electrolysis, hydrogen bubbles (2H ２ O + 2e － →H ２ +2OH － ) to the anode side, and also prevents the bubble-like oxygen (4OH) generated at the anode (positive electrode). － →O ２ +2H ２ O+4e － In order to prevent OH from migrating to the cathode side, a gas barrier separator (membrane) is disposed between the cathode and the anode. － Anion exchange membrane water electrolysis (AEMWE) has also been proposed, which uses an anion exchange membrane that efficiently transfers hydroxy ions. AEMWE can efficiently transfer hydroxy ions from the cathode to the anode without using a highly concentrated alkaline aqueous solution as the electrolyte.

[0004] Water electrolysis technology using a cation (proton) exchange membrane as a separator that also serves as an electrolyte is also known. ２ O → O ２ +4H ＋ +4e － The reaction occurs at the cathode, and ＋ +2e － →H２ The reaction occurs as follows: ＋ moves between the electrodes to couple the anodic and cathodic reactions.

[0005] Regarding ion exchange membranes used in separators in water electrolysis technology, for example, Patent Document 1 describes an invention for an ion exchange membrane for water electrolysis, which is an ion exchange membrane formed by laminating multiple porous substrate films, each having a porosity of 30 to 50% and an average pore diameter of 0.01 to less than 0.1 μm, with an ion exchange resin filling the pores of the laminated porous substrate film, wherein the porous substrate films have a total thickness of 50 to 200 μm and the difference in porosity between adjacent porous substrate films is 10% or less. The technology described in Patent Document 1 is said to be able to provide an ion exchange membrane for water electrolysis that has high gas barrier properties and low membrane resistance.

[0006] Japanese Patent Application Laid-Open No. 2018-127506

[0007] In alkaline water electrolysis and the like, separators are required to have high ion permeability (low ionic resistance) and low water permeability. An object of the present invention is to provide a separator having high ion permeability and low water permeability. Another object of the present invention is to provide a curable composition suitable for forming this separator. Another object of the present invention is to provide a method for producing a separator using this curable composition.

[0008] The above-mentioned problems of the present invention are solved by the following means: [1] A separator comprising a crosslinked product obtained by a curing reaction of any one of the following (a) to (d): (a) a compound represented by the following formula (I-1): In the above formula (I-1), X １ and Y represents a group having at least one of an epoxy group and an oxetanyl group, and n is a number equal to or greater than 2. (b) A combination of a compound represented by the following formula (I-2) with at least one of a polyfunctional epoxy compound having no polyethyleneoxy group and a polyfunctional oxetane compound having no polyethyleneoxy group: In the above formula (I-2), X ２ represents a hydrogen atom or a non-chain polymerizable organic group. Y and n have the same meanings as Y and n in formula (I-1). (c) A compound represented by the following formula (II-1): In the above formula (II-1), X ３ and Z represents a group having an allyl group, and n is a number of 2 or more. (d) A combination of a compound represented by the following formula (II-2) with a polyfunctional allyl compound having no polyethyleneoxy group: In the above formula (II-2), X ４ represents a hydrogen atom or a non-chain polymerizable organic group. Z and n are defined as Z and n in formula (II-1), respectively. However, when the crosslinked product is a crosslinked product obtained by a curing reaction of (a) above, the content of the component derived from the compound represented by formula (I-1) in the crosslinked product is 50% by mass or more; when the crosslinked product is a crosslinked product obtained by a curing reaction of (b) above, the content of the component derived from the compound represented by formula (I-2) in the crosslinked product is 50% by mass or more; when the crosslinked product is a crosslinked product obtained by a curing reaction of (c) above, the content of the component derived from the compound represented by formula (II-1) in the crosslinked product is 50% by mass or more; and when the crosslinked product is a crosslinked product obtained by a curing reaction of (d) above, the content of the component derived from the compound represented by formula (II-2) in the crosslinked product is 50% by mass or more. [2] The separator according to [1], wherein the curing reaction is a cationic polymerization reaction of (a) or (b) above. [3] The separator according to [2], wherein the cationic polymerization reaction is a reaction using at least one of a sulfonium salt and an iodonium salt as an acid generator. [4] The separator according to [3], wherein the cationic polymerization reaction is a reaction using a photosensitizer represented by the following formula (1): In formula (1), R １ and R ２represents an alkyl group. [5] The separator according to any one of [1] to [4], wherein the crosslinked product is a crosslinked product obtained by a curing reaction of (a) above. [6] The separator according to [5], wherein the curing reaction is carried out in the coexistence of an oxetane compound having no polyethyleneoxy group. [7] The separator according to any one of [1] to [4], wherein the crosslinked product is a crosslinked product obtained by a curing reaction of (b) above. [8] The separator according to [7], wherein the curing reaction is carried out in the coexistence of a monofunctional oxetane compound having no polyethyleneoxy group. [9] The separator according to any one of [1] to [8], wherein the separator further comprises a porous support.

[10] The separator according to any one of [1] to [9], for use as a diaphragm separating an anode and a cathode in water electrolysis.

[11] The separator according to

[10] , wherein the water electrolysis is alkaline water electrolysis.

[12] A curable composition comprising the following (a) or (b) and a photoacid generator or a thermal acid generator: (a) a compound represented by the following formula (I-1): In the above formula (I-1), X １ and Y represents a group having at least one of an epoxy group and an oxetanyl group, and n is a number equal to or greater than 2. (b) A combination of a compound represented by the following formula (I-2) with at least one of a polyfunctional epoxy compound having no polyethyleneoxy group and a polyfunctional oxetane compound having no polyethyleneoxy group: In the above formula (I-2), X ２ represents a hydrogen atom or a non-chain polymerizable organic group. Y and n are defined as Y and n in formula (I-1), respectively. However, when the curable composition contains (a), the content of the compound represented by formula (I-1) in the solid content of the curable composition is 50 mass% or more, and when the curable composition contains (b), the content of the compound represented by formula (I-2) in the solid content of the curable composition is 50 mass% or more.

[13] The curable composition according to

[12] , which contains the photoacid generator and a photosensitizer represented by the following formula (1): In formula (1), R １ and R ２represents an alkyl group.

[14] A method for producing a separator, comprising subjecting the curable composition according to

[12] or

[13] to a curing reaction to obtain a crosslinked body.

[15] A method for producing a separator according to

[14] , comprising subjecting the curable composition according to

[12] or

[13] in a state where the curable composition is impregnated into a porous support to a curing reaction to obtain a composite of the porous support and the crosslinked body.

[0009] In the present invention, an epoxy compound (oxirane compound) refers to a compound having at least one epoxy group (oxiranyl group) in one molecule. In other words, the term "epoxy compound" includes both monofunctional epoxy compounds having one epoxy group in one molecule and polyfunctional epoxy compounds having multiple epoxy groups in one molecule. Unless otherwise specified, an "epoxy compound" does not have an oxetanyl group or an allyl group. In the present invention, an oxetane compound refers to a compound having at least one oxetanyl group in one molecule. In other words, the term "oxetane compound" refers to both monofunctional oxetane compounds having one oxetanyl group in one molecule and polyfunctional oxetane compounds having multiple oxetanyl groups in one molecule. Unless otherwise specified, an "oxetane compound" does not have an epoxy group or an allyl group. In the present invention, an allyl compound refers to a compound having at least one allyl group in one molecule. That is, the term "allyl compound" includes both monofunctional allyl compounds having one allyl group in one molecule and polyfunctional allyl compounds having multiple allyl groups in one molecule. Unless otherwise specified, the "allyl compound" does not have an epoxy group or an oxetanyl group. The term "polyethyleneoxy group" refers to a structure in which two or more ethyleneoxy groups are repeated in a linear chain.

[0010] The separator of the present invention has high ion permeability and low water permeability. The curable composition of the present invention is suitable for forming the separator. Furthermore, the method for producing the separator of the present invention can provide a separator with high ion permeability and low water permeability.

[0011] [Separator] The separator of the present invention can be widely used as a separator in water electrolysis, such as alkaline water electrolysis, anion exchange membrane water electrolysis, and proton exchange membrane water electrolysis, and is suitable as a diaphragm separating an anode and a cathode in water splitting. The basic function of this diaphragm is to prevent gas generated at each electrode from moving to the other electrode. The separator of the present invention has this basic function and also has excellent ion permeability and low water permeability. The configuration of the separator of the present invention will be described.

[0012] The separator of the present invention contains a crosslinked product obtained by a curing reaction of any one of the following (a) to (d):

[0013] (a) A compound represented by the following formula (I-1):

[0014]

[0015] In the above formula (I-1), X １ and Y represent a group having at least one of an epoxy group and an oxetanyl group, and n is a number of 2 or more. In the present invention, the crosslinked product obtained by curing reaction of (a) has a content of a constituent component derived from the compound represented by formula (I-1) in this crosslinked product of 50 mass % or more.

[0016] (b) A combination of a compound represented by the following formula (I-2) and at least one of a polyfunctional epoxy compound having no polyethyleneoxy group and a polyfunctional oxetane compound having no polyethyleneoxy group.

[0017]

[0018] In the above formula (I-2), X ２ represents a hydrogen atom or a non-chain polymerizable organic group (a group that is non-chain polymerizable and has a carbon atom). Y and n have the same meanings as Y and n in formula (I-1), respectively, and the preferred ranges are also the same. In the present invention, the crosslinked product obtained by curing reaction of (b) above has a content of a constituent component derived from the compound represented by formula (I-2) above of 50 mass % or more in this crosslinked product.

[0019] (c) A compound represented by the following formula (II-1):

[0020]

[0021] In the above formula (II-1), X ３ and Z is an allyl group (CH ２ =CH-CH ２ -), and n is a number of 2 or more. In the present invention, the crosslinked product obtained by curing reaction of (c) has a content of the constituent component derived from the compound represented by formula (II-1) of 50 mass % or more.

[0022] (d) A combination of a compound represented by the following formula (II-2) and a polyfunctional allyl compound having no polyethyleneoxy group:

[0023]

[0024] In the above formula (II-2), X ４ represents a hydrogen atom or a non-chain polymerizable organic group. Z and n have the same meanings as Z and n in formula (II-1), respectively, and the preferred ranges are also the same. In the present invention, the crosslinked product obtained by curing reaction of (d) has a content of a component derived from the compound represented by formula (II-2) in this crosslinked product of 50 mass % or more.

[0025] The crosslinked material constituting the separator of the present invention has high water affinity due to the action of polyethyleneoxy groups, but is difficult to dissolve in water due to the crosslinked structure. It can also be made water-insoluble. Furthermore, because it is a crosslinked material, its mechanical strength is increased to a desired level. Furthermore, due to its structure, it tends to have excellent heat resistance and alkali resistance. The curing reaction to obtain the crosslinked material is preferably a cationic polymerization reaction or a radical polymerization reaction. The crosslinked material obtained by curing (a) or (b) is usually a crosslinked material obtained by a cationic polymerization reaction, while the crosslinked material obtained by curing (c) or (d) is usually a crosslinked material obtained by a radical polymerization reaction. Therefore, the curing reaction is carried out by mixing each of the compounds specified by (a) to (d) with a polymerization initiator. A sensitizer may also be added if necessary. Furthermore, in addition to each of the compounds specified by (a) to (d), reactive monomers other than the compounds specified by (a) to (d) may also be mixed and cured.

[0026] The crosslinked product preferably does not have a hydrolyzable structural moiety such as an ester bond, an amide bond, a urethane bond, or a urea bond. This allows the resulting separator to have higher alkali resistance. The separator of the present invention preferably contains a crosslinked product obtained by a curing reaction of (a).

[0027] The separator of the present invention can be in the form of a film formed from a crosslinked product obtained by a curing reaction of any of (a) to (d). The separator of the present invention can also be in the form of a film including a porous support and the crosslinked product. For example, the separator can be in the form of a laminate of a film of a crosslinked product obtained by a curing reaction of any of (a) to (d) and a porous support. Furthermore, a composite can be obtained by impregnating a porous support with a curable composition including any of (a) to (d) and subjecting it to a curing reaction, thereby forming a crosslinked product obtained by a curing reaction of any of (a) to (d) at least within the pores of the porous support.

[0028] The constituent materials and members of the separator of the present invention will be described.

[0029] <Crosslinked body obtained by curing reaction of (a)>

[0030] Compound represented by formula (I-1) The compound represented by formula (I-1) has a polyethyleneoxy group and a group selected from an epoxy group and an oxetanyl group at X １ and Y. That is, X １ and Y represents a group having at least one of an epoxy group (oxiranyl group) and an oxetanyl group. １ Preferably, X and Y represent a group having an epoxy group (oxiranyl group). The epoxy group and oxetanyl group may have an alkyl group as a substituent, and the alkyl group preferably has 1 to 3 carbon atoms. １ may have only one group selected from an epoxy group and an oxetanyl group, or may have two or more groups selected from an epoxy group and an oxetanyl group. Y may have only one group selected from an epoxy group and an oxetanyl group, or may have two or more groups selected from an epoxy group and an oxetanyl group, and preferably has only one of an epoxy group and an oxetanyl group. １Preferably, both X and Y have a structure having an epoxy group but not an oxetanyl group, or a structure having an oxetanyl group but not an epoxy group, and more preferably a structure having an epoxy group but not an oxetanyl group. Therefore, the compound represented by the above formula (I-1) preferably has a structure having an epoxy group but not an oxetanyl group, or a structure having an oxetanyl group but not an epoxy group, and more preferably a structure having an epoxy group but not an oxetanyl group. X １ Preferably, neither of Y has an allyl group.

[0031] X １ is preferably a monovalent saturated group having one or more of at least one of an epoxy group and an oxetanyl group and composed only of atoms selected from carbon atoms, oxygen atoms, and hydrogen atoms. １ It is preferable that the compound does not have active hydrogen (a hydrogen atom bonded to an oxygen atom, a nitrogen atom, or a sulfur atom).

[0032] X １ When X has only one group selected from an epoxy group and an oxetanyl group, １ The chemical formula weight of X is preferably 55 to 50,000, more preferably 55 to 10,000, and even more preferably 55 to 5,000. １ has only one group selected from an epoxy group and an oxetanyl group, at least one of the epoxy group and the oxetanyl group is bonded to X in formula (I-1) via an alkylene group. １ Preferably, the alkylene group is an unsubstituted alkylene group. The alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 3 carbon atoms. The epoxy group is bonded to the X １ When the alkylene group is bonded to an oxygen atom bonded to the above, a part of the alkylene group may form an alicyclic ring together with the epoxy group.

[0033] X １ When X has two or more groups selected from an epoxy group and an oxetanyl group, １is preferably a branched alkyl group having a group selected from an epoxy group and an oxetanyl group as a substituent. That is, it is preferably a branched alkyl group in which a group having a group selected from an epoxy group and an oxetanyl group is bonded to at least two branch ends of a branched alkyl chain (saturated hydrocarbon chain). The group having a group selected from an epoxy group and an oxetanyl group bonded to the at least two branch ends preferably has a chemical formula weight of 250 to 50,000, more preferably 300 to 50,000, and even more preferably 500 to 30,000. Furthermore, it is preferable that a polyethyleneoxy structure be present between at least two branch ends of the branched alkyl chain and the group selected from an epoxy group and an oxetanyl group. The group having a group selected from an epoxy group and an oxetanyl group bonded to the at least two branch ends is more preferably —O(C ２ H ４ O) ｎ -Y is preferably the same structure as that of the branched alkyl chain. The branched alkyl group having a group selected from an epoxy group and an oxetanyl group as a substituent preferably has 2 to 5, more preferably 2 to 4, and even more preferably 2 to 3 branched ends to which groups having a group selected from an epoxy group and an oxetanyl group are bonded as the structure of the branched alkyl chain portion (branched saturated hydrocarbon structure). The number of branched ends may include the number of X shown in formula (I-1) above. １ The oxygen atom bonded to the terminal end is not included.

[0034] X １ Preferred specific examples of the structure are shown below. In the following specific examples, * indicates a linking site, and m is an integer of 2 or more.

[0035]

[0036] Y is preferably a monovalent saturated group having one or more of at least one of an epoxy group and an oxetanyl group and composed only of atoms selected from carbon atoms, oxygen atoms, and hydrogen atoms, and preferably does not have active hydrogen (a hydrogen atom bonded to an oxygen atom, a nitrogen atom, or a sulfur atom).

[0037] Y preferably has at least one of an epoxy group and an oxetanyl group. When Y has only one group selected from an epoxy group and an oxetanyl group, the chemical formula weight of Y is preferably 55 to 300, more preferably 55 to 200, and even more preferably 55 to 150. When Y has only one group selected from an epoxy group and an oxetanyl group, the epoxy group or oxetanyl group is preferably bonded to the oxygen atom bonded to Y in formula (I-1) via an alkylene group. This alkylene group is preferably an unsubstituted alkylene group. Furthermore, the number of carbon atoms in this alkylene group is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 3. When an epoxy group is bonded to the oxygen atom bonded to Y in formula (I-1) via an alkylene group, a part of the alkylene group may form an alicyclic ring together with the epoxy group.

[0038] Preferred specific examples of the structure of Y are shown below, where * indicates a linking site.

[0039]

[0040] In formula (I-1), n ​​represents an integer of 2 or more, preferably 2 to 1,000, more preferably 3 to 500, even more preferably 4 to 300, and still more preferably 5 to 200.

[0041] The above (a) can contain one or more compounds represented by formula (I-1).

[0042] Preferred specific examples of the compound represented by formula (I-1) are shown below, but the present invention is not limited to these. In the following specific examples, * indicates a linking site, and n is an integer of 2 or more.

[0043]

[0044] In the crosslinked body obtained by the curing reaction of (a), as long as the content of the constituent component derived from the compound represented by formula (I-1) is 50 mass% or more, the crosslinked body may contain a constituent component derived from at least one of the compound represented by formula (I-2), the compound represented by formula (II-1), and the compound represented by formula (II-2).

[0045] The curing reaction of (a) may be carried out in the presence of at least one of an oxetane compound not having a polyethyleneoxy group and an epoxy compound not having a polyethyleneoxy group, and is preferably carried out in the presence of an oxetane compound not having a polyethyleneoxy group. When the curing reaction of (a) is carried out in the presence of an oxetane compound not having a polyethyleneoxy group, the compound represented by formula (I-1) above is preferably an epoxy compound (a compound having an epoxy group but not an oxetanyl group). When the curing reaction of (a) is carried out in the presence of an epoxy compound not having a polyethyleneoxy group, the compound represented by formula (I-1) above is preferably an oxetane compound (a compound having an oxetanyl group but not an epoxy group).

[0046] - Oxetane Compound Having No Polyethyleneoxy Group - The oxetane compound having no polyethyleneoxy group is preferably an oxetane compound that does not have a polyethyleneoxy group and is composed only of atoms selected from carbon atoms, oxygen atoms, and hydrogen atoms. The oxetane compound having no polyethyleneoxy group preferably does not have a hydrolyzable structural moiety such as an ester bond in its molecular structure. The oxetane compound having no polyethyleneoxy group may be a monofunctional oxetane compound or a polyfunctional oxetane compound. In the case of a polyfunctional oxetane compound, the number of oxetanyl groups in the polyfunctional oxetane compound is preferably 2 to 6, more preferably 2 to 4, even more preferably 2 to 3, and even more preferably 2.

[0047] The molecular weight of the oxetane compound having no polyethyleneoxy group is preferably 80 to 1,000, more preferably 100 to 1,000, more preferably 100 to 500, and even more preferably 100 to 250.

[0048] Preferred specific examples of the oxetane compound having no polyethyleneoxy group are shown below, but the present invention is not limited to these.

[0049]

[0050] - Epoxy Compound Having No Polyethyleneoxy Group - The epoxy compound having no polyethyleneoxy group is preferably an epoxy compound that does not have a polyethyleneoxy group and is composed only of atoms selected from carbon atoms, oxygen atoms, and hydrogen atoms. The epoxy compound having no polyethyleneoxy group preferably does not have a hydrolyzable structural moiety such as an ester bond in its molecular structure. The epoxy compound having no polyethyleneoxy group may be a monofunctional epoxy compound or a polyfunctional epoxy compound. In the case of a polyfunctional epoxy compound, the number of epoxy groups in the polyfunctional epoxy compound is preferably 2 to 6, more preferably 2 to 5, and even more preferably 3 to 4. The epoxy compound having no polyethyleneoxy group may have a vinyl group.

[0051] The molecular weight of the epoxy compound having no polyethyleneoxy group is preferably 150 to 1,000, more preferably 150 to 600, and particularly preferably 200 to 400.

[0052] Preferred specific examples of epoxy compounds having no polyethyleneoxy group are shown below, but the present invention is not limited to these. In the following specific examples, * indicates a linking site.

[0053]

[0054]

[0055] In the crosslinked product obtained by curing reaction of (a), the content of the constituent component derived from the compound represented by formula (I-1) in the crosslinked product is 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more. The content of the constituent component derived from the compound represented by formula (I-1) in the crosslinked product may be 100% by mass (i.e., a form in which all of the reactive monomers have been cured as the compound represented by formula (I-1)).

[0056] When the curing reaction of (a) is carried out in the coexistence of at least one of an oxetane compound having no polyethyleneoxy group and an epoxy compound having no polyethyleneoxy group, in the crosslinked product obtained by the curing reaction of (a), the total amount of components derived from the oxetane compound having no polyethyleneoxy group and components derived from the compound having no polyethyleneoxy group in this crosslinked product is 50 mass% or less, preferably 5 to 40 mass%, more preferably 10 to 40 mass%, and more preferably 10 to 30 mass%. Note that the above "total" refers to the components derived from the epoxy compound having no polyethyleneoxy group when the crosslinked product does not have a component derived from the oxetane compound having no polyethyleneoxy group, and refers to the components derived from the oxetane compound having no polyethyleneoxy group when the crosslinked product does not have a component derived from the epoxy compound having no polyethyleneoxy group.

[0057] <Crosslinked body obtained by curing reaction of (b)>

[0058] Compound represented by formula (I-2) The compound represented by formula (I-2) has a polyethyleneoxy group and a hydrogen atom or a non-chain polymerizable organic group in X ２ and further has a group selected from an epoxy group and an oxetanyl group as Y.

[0059] X ２represents a hydrogen atom or a non-chain polymerizable organic group. Here, the "non-chain polymerizable organic group" is an organic group that does not undergo chain polymerization. In other words, it means an organic group that does not have an organic group that undergoes chain polymerization (for example, groups having a carbon-carbon double bond such as a vinyl group, a vinyl ether group, a vinyl thioether group, a styryl group, an acryloyl group, a methacryloyl group, and derivatives thereof; and cyclic ether groups such as an epoxy group and an oxetanyl group). X ２ It is preferable that the compound does not have active hydrogen (a hydrogen atom bonded to an oxygen atom, a nitrogen atom, or a sulfur atom).

[0060] X ２ The chemical formula weight of X is preferably 1 to 500, more preferably 1 to 300, even more preferably 1 to 100, and particularly preferably 1 to 50. ２ Examples of the non-chain polymerizable organic group that can be used as X include an alkyl group, an aryl group, and an aralkyl group, and an unsubstituted alkyl group is preferred. The number of carbon atoms in this alkyl group is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 3. ２ is preferably a hydrogen atom or an unsubstituted alkyl group.

[0061] X ２ Preferred examples of the structure are shown below, where * indicates a linking site.

[0062]

[0063] Y and n have the same meanings as Y and n in formula (I-1), respectively, and the preferred ranges are also the same. Y is preferably a group having at least one of an epoxy group and an oxetanyl group. Therefore, the compound represented by formula (I-2) above preferably has a structure having an epoxy group but not an oxetanyl group, or a structure having an oxetanyl group but not an epoxy group, and more preferably has a structure having an epoxy group but not an oxetanyl group.

[0064] The above (b) can contain one or more compounds represented by formula (I-2).

[0065] Preferred specific examples of the compound represented by formula (I-2) are shown below, but the present invention is not limited to these. In the following specific examples, n is an integer of 2 or more.

[0066]

[0067] - Polyfunctional epoxy compound having no polyethyleneoxy group - As the polyfunctional epoxy compound having no polyethyleneoxy group in (b), a polyfunctional epoxy compound having no polyethyleneoxy group among the epoxy compounds having no polyethyleneoxy group explained in (a) above can be used.

[0068] Polyfunctional oxetane compound having no polyethyleneoxy group: As the polyfunctional oxetane compound having no polyethyleneoxy group in (b), a polyfunctional oxetane compound having no polyethyleneoxy group, among the oxetane compounds having no polyethyleneoxy group explained in (a) above, can be used.

[0069] The polyfunctional epoxy compound having no polyethyleneoxy group and the polyfunctional oxetane compound having no polyethyleneoxy group preferably do not have a hydrolyzable structural portion such as an ester bond in their molecular structure.

[0070] In (b), when the compound represented by formula (I-2) is an epoxy compound, it is preferable to use a polyfunctional epoxy compound that does not have a polyethyleneoxy group. In this case, it is also preferable to further use an oxetane compound that does not have a polyethyleneoxy group, as explained in (a) above. In (b), when the compound represented by formula (I-2) is an oxetane compound, it is preferable to use a polyfunctional oxetane compound that does not have a polyethyleneoxy group. In this case, it is also preferable to further use an epoxy compound that does not have a polyethyleneoxy group, as explained in (a) above.

[0071] In the crosslinked product obtained by curing reaction of (b), the content of the constituent component derived from the compound represented by formula (I-2) in the crosslinked product is 50% by mass or more, preferably 55 to 98% by mass, more preferably 60 to 95% by mass, and particularly preferably 65 to 90% by mass.

[0072] In the crosslinked product obtained by curing (b), the total content of the components derived from the polyfunctional epoxy compound having no polyethyleneoxy groups and the components derived from the polyfunctional oxetane compound having no polyethyleneoxy groups is 50% by mass or less, preferably 2 to 45% by mass, more preferably 5 to 40% by mass, and even more preferably 10 to 35% by mass. Note that the term "total" refers to the components derived from the polyfunctional epoxy compound having no polyethyleneoxy groups when the crosslinked product does not contain any components derived from the polyfunctional oxetane compound having no polyethyleneoxy groups. Alternatively, it refers to the components derived from the polyfunctional oxetane compound having no polyethyleneoxy groups when the crosslinked product does not contain any components derived from the polyfunctional epoxy compound having no polyethyleneoxy groups. It is also preferable that the crosslinked product contains a component derived from a monofunctional oxetane compound having no polyethyleneoxy groups in the remainder excluding the above-mentioned components. In the curing reaction of (b), at least one of a monofunctional epoxy compound having no polyethyleneoxy groups and a monofunctional oxetane compound having no polyethyleneoxy groups may be further used. The monofunctional epoxy compound having no polyethyleneoxy group and the monofunctional oxetane compound having no polyethyleneoxy group preferably do not have a hydrolyzable structural portion such as an ester bond in their molecular structure.

[0073] In the curing reaction of (b), as long as the content of the constituent component derived from the compound represented by formula (I-2) is 50 mass% or more in the obtained crosslinked product, the curing reaction may be carried out together with at least one of the compound represented by formula (I-1), the compound represented by formula (II-1), and the compound represented by formula (II-2); however, it is preferable not to carry out the curing reaction together with these compounds.

[0074] <Crosslinked body obtained by curing reaction of (c)>

[0075] - Compound represented by formula (II-1) - Compound represented by formula (II-2) has a polyethyleneoxy group and an allyl group (-CH ２ -CH=CH ２ ) to X ３ The allyl group may have an alkyl group as a substituent, and the alkyl group preferably has 1 to 3 carbon atoms. ３ may have only one allyl group, or may have two or more allyl groups. Z may have only one allyl group, or may have two or more allyl groups, and preferably has only one allyl group. X ３ and Z preferably does not have an epoxy group or an oxetanyl group.

[0076] X ３ is preferably a monovalent group having one or more allyl groups and composed only of atoms selected from carbon atoms, oxygen atoms, and hydrogen atoms.

[0077] X ３ When X has only one allyl group, ３ The chemical formula weight of X is preferably 40 to 100, more preferably 40 to 80, and even more preferably 40 to 60. ３ When X has only one allyl group, the allyl group is bonded to X in formula (II-1) directly or via an alkylene group. ３ Preferably, the alkylene group is bonded to an oxygen atom bonded to X. The alkylene group is preferably an unsubstituted alkylene group. The number of carbon atoms in the alkylene group is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 3. ３ is particularly preferably an allyl group.

[0078] X ３ When X has two or more allyl groups, ３is preferably a branched alkyl group having an allyl group as a substituent. That is, it is preferably a branched alkyl group in which a group having an allyl group is bonded to at least two branched ends of a branched alkyl chain. The group having an allyl group bonded to the at least two branched ends preferably has a chemical formula weight of 40 to 50,000, more preferably 40 to 20,000. In addition, it is preferable that a polyethyleneoxy structure be present between at least two branched ends of the branched alkyl chain and the allyl group. The group having an allyl group bonded to the at least two branched ends is more preferably -O(C ２ H ４ O) ｎ -Z. The branched alkyl chain may contain an oxygen atom in the chain. The branched alkyl group having an allyl group as a substituent preferably has 2 to 6 branched ends, more preferably 2 to 5 branched ends, and even more preferably 3 to 4 branched ends, to which groups having allyl groups are bonded, as the structure of the branched alkyl chain portion (branched saturated hydrocarbon structure). The number of branched ends depends on the number of X shown in formula (II-1) above. ３ The oxygen atom bonded to the terminal end is not included.

[0079] X ３ Preferred specific examples of the structure are shown below. In the following specific examples, * indicates a linking site, and t is an integer of 2 or more.

[0080]

[0081] Z is preferably a monovalent group having one or two allyl groups and composed only of atoms selected from carbon atoms, oxygen atoms, and hydrogen atoms. An allyl group or a monovalent group combining an allyl group and an alkyl group is preferred. Z preferably has only one allyl group. When Z has only one allyl group, the chemical formula weight of Z is preferably 40 to 100, more preferably 40 to 80, and even more preferably 40 to 60. When Z has only one allyl group, it is preferred that the allyl group is bonded to the oxygen atom bonded to Z in formula (II-1) directly or via an alkyl group. This alkyl group is preferably an unsubstituted alkyl group, and the number of carbon atoms in this alkyl group is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 3.

[0082] n has the same meaning as n in formula (I-1), and the preferred range is also the same.

[0083] The above (c) can contain one or more compounds represented by formula (II-1).

[0084] Preferred specific examples of the compound represented by formula (II-1) are shown below, but the present invention is not limited to these. In the following specific examples, * indicates a linking site, and n is an integer of 2 or more.

[0085]

[0086] In the crosslinked body obtained by the curing reaction of (c), as long as the content of the component derived from the compound represented by formula (II-1) is 50 mass% or more, the crosslinked body may contain a component derived from at least one of the compound represented by formula (II), the compound represented by formula (I-I), the compound represented by formula (I-2), and the compound represented by formula (II-2); however, it is preferable that the crosslinked body does not contain any component derived from these compounds.

[0087] In the curing reaction of (c), in addition to the compound represented by formula (II-1), an allyl compound having no polyethyleneoxy group (a compound having an allyl group) may be used as a reactive monomer.

[0088] - Allyl Compound Having No Polyethyleneoxy Group - The allyl compound having no polyethyleneoxy group (compound having an allyl group) is preferably a monofunctional allyl compound or a polyfunctional allyl compound that does not have a polyethyleneoxy group and is composed of atoms selected from carbon atoms, oxygen atoms, and hydrogen atoms. In the case of a polyfunctional allyl compound, the number of allyl groups that the polyfunctional allyl compound has is preferably 2 to 6, more preferably 2 to 5, and even more preferably 3 to 4. The allyl compound having no polyethyleneoxy group preferably does not have a hydrolyzable structural moiety such as an ester bond in its molecular structure.

[0089] The molecular weight of the allyl compound having no polyethyleneoxy group is preferably 90 to 1,000, more preferably 150 to 600, and particularly preferably 250 to 300.

[0090] Preferred specific examples of allyl compounds not having a polyethyleneoxy group are shown below, but the present invention is not limited to these.

[0091]

[0092] In the crosslinked product obtained by curing reaction of (c), the content of the constituent component derived from the compound represented by formula (II-1) in the crosslinked product is 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, and particularly preferably 80% by mass or more. The content of the constituent component derived from the compound represented by formula (II-1) in the crosslinked product may be 100% by mass.

[0093] When the curing reaction of (c) is carried out in the coexistence of an allyl compound having no polyethyleneoxy group, the content of the constituent component derived from the allyl compound having no polyethyleneoxy group in the crosslinked product obtained by the curing reaction of (c) is 50% by mass or less, preferably 5 to 40% by mass, and more preferably 10 to 40% by mass.

[0094] <Crosslinked body obtained by curing reaction of (d)>

[0095] - Compound represented by formula (II-2) - The compound represented by formula (II-2) has a polyethyleneoxy group and a non-chain polymerizable organic group represented by X ４and further has an allyl group in Z. ４ represents X in formula (I-2). ２ The definitions and preferred ranges of Z and n are the same as those of Z and n in formula (II-1), respectively. The definitions and preferred ranges of Z and n are the same as those of Z and n in formula (II-1), respectively. Z is preferably a group having one allyl group.

[0096] The above (d) can contain one or more compounds represented by formula (II-2).

[0097] Preferred specific examples of the compound represented by formula (II-2) are shown below, but the present invention is not limited to these. In the following specific examples, n is an integer of 2 or more.

[0098]

[0099] As the polyfunctional allyl compound having no polyethyleneoxy group, it is possible to use the polyfunctional allyl compound having no polyethyleneoxy group among the allyl compounds having no polyethyleneoxy group explained in (c) above.

[0100] In the curing reaction of (d), a monofunctional allyl compound having no polyethyleneoxy group may be further used. As the monofunctional allyl compound having no polyethyleneoxy group, among the allyl compounds having no polyethyleneoxy group described in (c) above, a monofunctional allyl compound having no polyethyleneoxy group can be used.

[0101] In the crosslinked product obtained by curing reaction of (d), the content of the constituent component derived from the compound represented by formula (II-2) in the crosslinked product is 50% by mass or more, preferably 55 to 98% by mass, more preferably 60 to 95% by mass, and particularly preferably 65 to 90% by mass.

[0102] In the crosslinked body obtained by the curing reaction of (d), the content of the component derived from the polyfunctional allyl compound having no polyethyleneoxy group in this crosslinked body is 50% by mass or less, preferably 2 to 45% by mass, more preferably 5 to 40% by mass, and even more preferably 10 to 35% by mass. The crosslinked body may contain a component derived from the monofunctional allyl compound having no polyethyleneoxy group as the remainder excluding the above-mentioned components.

[0103] In the curing reaction (d), as long as the content of the constituent component derived from the compound represented by formula (II-2) is 50 mass% or more in the obtained crosslinked product, the curing reaction may be carried out together with at least one of the compound represented by formula (I-1), the compound represented by formula (I-2), and the compound represented by formula (II-1); however, it is preferable not to carry out the curing reaction together with these compounds.

[0104] The crosslinked product obtained by curing any one of (a) to (d) may contain other components in addition to the components described above, such as a component derived from an acid generator, a component derived from a polymerization initiator, and / or a photosensitizer, as described below.

[0105] The curing reaction for obtaining a crosslinked product by curing (a) or (b) is preferably a cationic polymerization reaction. This cationic polymerization reaction is preferably a reaction using an acid generator (a photoacid generator or a thermal acid generator) as a polymerization initiator, more preferably a reaction using at least one of a sulfonium salt and an iodonium salt as the acid generator. This cationic polymerization reaction is preferably a reaction using a photosensitizer.

[0106] <Acid Generator> As the acid generator (photoacid generator and thermal acid generator), any conventional compound used in the ring-opening reaction of epoxy groups and oxetanyl groups can be used without any particular limitation. In particular, sulfonium salts or iodonium salts can be preferably used. Nonionic acid generators and ferrocene-based (having a ferrocene structure) acid generators can also be used. For more information on photoacid generators, please refer to the description in Journal of the Adhesion Society of Japan, Vol. 56, No. 10 (2020), pp. 403-414.

[0107] Specific preferred examples of the photoacid generator or thermal acid generator are shown below.

[0108]

[0109]

[0110] The amount of the photoacid generator or thermal acid generator used is preferably 0.5 to 15 parts by mass, more preferably 1 to 12 parts by mass, and still more preferably 1.5 to 9 parts by mass, relative to 100 parts by mass of the total amount of reactive monomers used in the curing reaction of (a) or (b) above (the total amount of all polymerizable monomers that undergo polymerization in the polymerization reaction to obtain the crosslinked body of the present invention).

[0111] <Photosensitizer> When a photoacid generator is used in the curing reaction (a) or (b) above, a photosensitizer can be further used for the purpose of controlling the exposure sensitivity and / or photosensitive wavelength. The photosensitizer is not particularly limited, and conventional photosensitizers can be used. Among them, an anthracene compound represented by the following formula (1) can be preferably used.

[0112]

[0113] In formula (1), R １ and R ２ represents an alkyl group. １ and R ２ The alkyl group that can be taken as the alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms.

[0114] Preferred specific examples of the photosensitizer are shown below, but the present invention is not limited to these.

[0115]

[0116] In the curing reaction of (a) or (b) above, the amount of the photosensitizer used is preferably 0.5 to 15 parts by mass, more preferably 1 to 12 parts by mass, and still more preferably 1.5 to 9 parts by mass, relative to 100 parts by mass of the total of the reactive monomers used in the curing reaction of (a) or (b).

[0117] The curing reaction for obtaining a crosslinked product by curing (c) or (d) above is preferably a radical polymerization reaction, which can be carried out using a conventional polymerization initiator such as an organic peroxide.

[0118] The amount of the polymerization initiator used is preferably 0.5 to 15 parts by mass, more preferably 1 to 12 parts by mass, and still more preferably 1.5 to 9 parts by mass, relative to 100 parts by mass in total of the reactive monomers used in the curing reaction of (c) or (d).

[0119] The conditions for the curing reaction to obtain a crosslinked product by curing any of the above (a) to (d) can be appropriately set with reference to the usual curing reaction conditions for epoxy compounds, oxetane compounds, and vinyl compounds. It is also preferable to perform a post-baking treatment to ensure complete curing. In the case of a photocuring reaction, the illuminance of the light used for irradiation is 1 to 100 mW / cm at 365 nm. ２ is preferred, and 5 to 50 mW / cm ２ The exposure dose is preferably 50 to 5000 mJ / cm ２ is preferred, and 100 to 1000 mJ / cm ２ The photocuring reaction can also be carried out using an electron beam (EB) at a dose of 100 to 2000 kGy. In the case of a thermal curing reaction, the heating temperature is preferably 50 to 200°C, more preferably 60 to 150°C, and even more preferably 70 to 100°C. The heating time is preferably 0.5 to 60 minutes, and more preferably 1 to 30 minutes.

[0120] <Porous Support> The porous support is not particularly limited as long as it has pores that allow water and ions to pass through. The porous support preferably has numerous fine pores that penetrate from the front surface to the back surface. For example, a porous support used in a separator for water splitting can be used. The material of the porous support is preferably a resin. For example, a porous support made of polyphenylene sulfide, polysulfone, polypropylene, polyethylene, polymethylpentene, polyvinylidene fluoride, polytetrafluoroethylene, or the like can be used. The porous support may have any porous structure, and may be a membrane formed by stretching a resin film to form pores, a woven fabric, or a nonwoven fabric. The porous support may further have an inorganic particle layer or may contain composite inorganic particles. Examples of inorganic particles include zirconium oxide and magnesium hydroxide. In the present invention, the porous support is preferably a polypropylene / polyethylene nonwoven fabric, a polyphenylene sulfide nonwoven fabric, or a polysulfone-zirconium oxide composite porous membrane.

[0121] The thickness of the porous support is preferably from 1 to 500 μm, more preferably from 5 to 400 μm, even more preferably from 10 to 300 μm, and particularly preferably from 20 to 200 μm.

[0122] The porosity of the porous support is preferably 10 to 99%, more preferably 20 to 95%, even more preferably 30 to 90%, and particularly preferably 40 to 80%. The porosity can be determined by calculation from the apparent volume and the theoretical volume, and specifically, can be determined as follows. - Method of calculating porosity - The apparent volume of the porous support (the volume of the entire porous support including the volume of the pores) is calculated as X (cm ３ ), the weight of the porous support is W (g), the true density of the porous support is d (g / cm ３ ) and X and the theoretical volume Y (cm ３ ) (Y = W / d) and calculated using the following formula: Porosity (%) = [1 - (Y / X)] x 100

[0123] As the porous support, for example, the “porous substrate film” and “laminated porous substrate film” described in paragraphs

[0018] to

[0023] of JP-A-2018-127506, and the “microporous membrane” described in paragraph

[0022] of JP-A-2022-181107 can be referred to.

[0124] When the separator of the present invention is composed of a membrane formed of a crosslinked product obtained by a curing reaction of any of (a) to (d) (a free-standing membrane), the thickness of this membrane is preferably 10 to 500 μm, more preferably 20 to 400 μm, even more preferably 30 to 300 μm, and particularly preferably 40 to 200 μm. When the separator of the present invention is in the form of a laminate of a membrane formed of a crosslinked product obtained by a curing reaction of any of (a) to (d) (a crosslinked membrane) and a porous support, the thickness of the crosslinked membrane is preferably 1 to 500 μm, more preferably 2 to 400 μm, even more preferably 3 to 300 μm, and particularly preferably 4 to 200 μm. The thickness of the porous support is as described above. When the separator of the present invention is in the form of a composite in which a crosslinked body is formed at least in the pores of the porous support, the thickness of this composite is preferably 1 to 500 μm, more preferably 2 to 400 μm, even more preferably 3 to 300 μm, and particularly preferably 4 to 200 μm. The thickness of the separator of the present invention can be determined by measuring the thickness at five random locations using a constant pressure thickness meter (e.g., DG-525H manufactured by Ono Sokki Co., Ltd.) and calculating the arithmetic average. The thickness of the porous support described above can also be determined in a similar manner. The thickness of the separator of the present invention is measured after drying the separator to remove moisture.

[0125] The ionic resistance of the separator of the present invention is 1.00 Ω cm when a 30% by mass potassium hydroxide solution is used at 80°C. ２ Preferably, it is less than 0.50 Ω cm ２ More preferably, it is less than 0.20 Ω cm ２ The ionic resistance of the separator of the present invention is usually less than 0.01 Ω cm. ２ The ionic resistance of the separator can be measured by the method described in the Examples.

[0126] The water permeability of the separator of the present invention is 300 mL / min cm ２ Preferably, the pressure is less than 100 mL / min cm ２ More preferably, it is less than 20 mL / min cm ２ The water permeability of the separator can be measured by the method described in the Examples.

[0127] The separator of the present invention is suitable as a diaphragm separating an anode and a cathode in water electrolysis. For example, it can be used as a separator in alkaline water electrolysis (AWE), anion exchange membrane water electrolysis (AEMWE), and proton exchange membrane water electrolysis (PEMWE). The separator of the present invention can be suitably used in alkaline water electrolysis and anion exchange membrane water electrolysis, and is particularly suitable for alkaline water electrolysis. The separator of the present invention can also be made to have excellent heat resistance, alkali resistance, etc., and such a separator can be suitably used in environments of 80 to 90°C or for alkaline water electrolysis using a highly concentrated alkaline aqueous solution. Although the separator of the present invention does not usually have cationic or anionic groups, it can also be used for alkaline water electrolysis, anion exchange membrane water electrolysis, and proton exchange membrane water electrolysis. This is because the highly hydrophilic polyethyleneoxy structure can incorporate and conduct hydroxy ions and protons together with water into the separator.

[0128] [Curable Composition] The curable composition of the present invention is a curable composition suitable for forming a crosslinked product by curing either (a) or (b) above.

[0129] The curable composition of the present invention contains (a) or (b) and an acid generator (a photoacid generator or a thermal acid generator). When the curable composition contains (a), the content of the compound represented by formula (I-1) in the solid content of the curable composition is 50 mass% or more. When the curable composition contains (b), the content of the compound represented by formula (I-2) in the solid content of the curable composition is 50 mass% or more. (a) and (b) in the curable composition of the present invention are the same as (a) and (b) in the separator of the present invention described above, respectively. The same applies to reactive monomers that can be used in combination (in the case of (a), at least one of a compound represented by formula (I-2), a compound represented by formula (II-1), and a compound represented by formula (II-2), an oxetane compound having no polyethyleneoxy group, an epoxy compound having no polyethyleneoxy group, etc.; in the case of (b), at least one of a monofunctional epoxy compound having no polyethyleneoxy group and a monofunctional oxetane compound having no polyethyleneoxy group, or at least one of a compound represented by formula (I-1), a compound represented by formula (II-1), and a compound represented by formula (II-2)). When the curable composition of the present invention contains a photoacid generator, it may further contain a photosensitizer. The preferred aspects and contents of (a) and (b), the reactive monomer that can be used in combination, the acid generator, and the photosensitizer in the curable composition of the present invention are the same as the preferred aspects and contents of (a) and (b), the acid generator, and the photosensitizer described in the separator of the present invention.

[0130] The curable composition of the present invention may contain a solvent. Examples of the solvent include acetonitrile, 4-methyl-2-pentanone, methyl ethyl ketone, 1,2-dimethoxyethane, butyl acetate, and ethyl acetate. When a solvent is used, the solid content in the curable composition of the present invention is preferably 1% by mass or more and 99% by mass or less, more preferably 5% by mass or more and 95% by mass or less, and even more preferably 10% by mass or more and 90% by mass or less.

[0131] [Method for Producing Separator] The method for producing a separator of the present invention includes subjecting the curable composition of the present invention to a curing reaction to obtain a crosslinked body. A preferred embodiment of the method for producing a separator of the present invention includes, for example, a step of obtaining a composite of a porous support and a crosslinked body by subjecting a porous support impregnated with the curable composition of the present invention to a curing reaction. The conditions for the curing reaction are the same as those for obtaining a crosslinked body obtained by curing any of the above-mentioned (a) to (d).

[0132] The present invention will be described in more detail below based on examples, but the present invention should not be construed as being limited thereto.

[0133] The raw materials listed in the table below were prepared. Mn is the number average molecular weight.

[0134]

[0135]

[0136] [Preparation of Curable Compositions] Curable compositions 1 to 10 were prepared by mixing the components in the mass ratios shown in the table below. The "Formula" column in the table indicates which of the compounds represented by formula (I-1), formula (I-2), formula (II-1), and formula (II-2) is contained in the curable composition. Furthermore, the "(a) to (d)" column in the table indicates which of (a) to (d) the compound falls into.

[0137]

[0138] [Preparation of Separator] Example 1 A 7 cm x 7 cm polypropylene / polyethylene nonwoven fabric (manufactured by Freudenberg, film thickness approximately 100 μm) was prepared as a porous support, and this nonwoven fabric was attached to a 10 cm x 10 cm glass plate using Kapton tape. 2 ml of curable composition 1 in the table above was applied to the nonwoven fabric, and the nonwoven fabric was impregnated with curable composition 1. Thereafter, the nonwoven fabric was illuminated at 10 mW / cm with a mercury-xenon lamp (trade name: EXECURE-3000, manufactured by HOYA Corporation). ２ (value at 365 nm), exposure dose 500 mJ / cm ２After exposure under the conditions, the film was post-baked at 90°C for 10 minutes using a hot plate. After post-baking, the glass plate was removed. In this way, the separator of Example 1 was obtained. The thickness of this separator was about 100 µm, the same as the thickness of the original nonwoven fabric.

[0139] Example 2 A separator of Example 2 was obtained in the same manner as in the production of the separator of Example 1, except that curable composition 2 was used instead of curable composition 1.

[0140] Example 3 A separator of Example 3 was obtained in the same manner as in the production of the separator of Example 1, except that curable composition 3 was used instead of curable composition 1.

[0141] Example 4 A separator of Example 4 was obtained in the same manner as in the production of the separator of Example 1, except that curable composition 4 was used instead of curable composition 1.

[0142] <Examples 5 to 7> Separators of Examples 5 to 7 were obtained in the same manner as in the production of the separator of Example 1, except that curable compositions 5 to 7 were used instead of curable composition 1.

[0143] Examples 8 to 9 Nonwoven fabrics were impregnated with curable compositions 8 to 9 in the same manner as in the production of the separator of Example 1, except that curable compositions 8 to 9 were used instead of curable composition 1. The nonwoven fabrics were then irradiated with an electron beam (EB) at an acceleration voltage of 80 keV and a dose of 1,000 kGy. In this way, the separators of Examples 8 to 9 were obtained. The thickness of these separators was approximately 100 μm, the same as the thickness of the original nonwoven fabric.

[0144] Comparative Example 1 A commercially available anion exchange membrane for water electrolysis, Sustainion manufactured by Dioxide Material, was used as the separator of Comparative Example 1.

[0145] Comparative Example 2 The separator of Comparative Example 2 was made of the above polypropylene-polyethylene nonwoven fabric alone.

[0146] Comparative Example 3 A separator of Comparative Example 3 was obtained in the same manner as in the production of the separator of Example 1, except that curable composition 10 was used instead of curable composition 1.

[0147] [Evaluation of Ion Resistance] Each of the separators was immersed in a 30% by mass potassium hydroxide solution (manufactured by Kanto Chemical Co., Inc.) at room temperature (25°C) overnight (20 hours). The separator was punched out into a circle with a diameter of 10 mm, and each of the obtained circular pieces was set in a cell and measured for ionic resistance (unit: Ω cm) at 80°C by an AC impedance method. ２ The ionic resistance thus obtained was evaluated according to the following evaluation criteria. - Evaluation criteria for ionic resistance - A: 0.20 Ω·cm ２ Less than B: 0.20 Ω cm ２ 0.50Ω・cm or more ２ Less than C: 0.50 Ω cm ２ 1.00Ω・cm or more ２ Less than D: 1.00 Ω cm ２ End

[0148] [Evaluation of Water Permeability] Each of the separators was punched into a circle with a diameter of 47 mm. Each of the obtained circular pieces was set in a pressure-resistant filter holder (product number XX4004700, manufactured by Merck). Pure water was passed through each circular piece for 30 seconds under conditions of room temperature (25°C) and a gauge pressure of 1 bar, and the amount of pure water that permeated (mL) was measured, and the unit was converted to water permeability (mL / min cm). ２ The permeability was calculated and evaluated according to the following criteria: -Evaluation criteria for water permeability- A: 20 mL / min cm ２ Less than bar B: 20 ​​mL / min cm ２ ・Over bar 100mL / min・cm ２ Less than bar C: 100 mL / min cm ２ ・Over bar 300mL / min・cm ２ Less than bar D: 300 mL / min cm ２ ・Bar or above

[0149]

[0150] [Evaluation of Heat Resistance and Alkali Resistance] The separators of Examples 1 to 7 and Comparative Example 3 were each immersed in a 30 wt % aqueous solution of potassium hydroxide and left to stand at 90°C for 24 hours. Thereafter, the water permeability of these separators was measured according to the above [Evaluation of Water Permeability]. The rate of increase in water permeability after 24 hours at 90°C relative to the water permeability before 24 hours at 90°C (water permeability measured in the above [Evaluation of Water Permeability]) was determined and evaluated according to the following evaluation criteria. The results are shown in Table 5. The higher the heat resistance and alkali resistance, the smaller the increase in water permeability. -Evaluation Criteria for Heat Resistance and Alkali Resistance- A: Less than 10% B: 10% or more but less than 20% C: 20% or more but less than 30% D: 30% or more

[0151]

[0152] The separator of Comparative Example 1 is an anion exchange membrane and does not contain a crosslinked body obtained by a curing reaction of any of the above (a) to (d). The separator of Comparative Example 1 has a dense separator structure, which reduces water permeability, but has an ionic resistance of 1.00 Ω cm. ２ or more. It was estimated that the alkali resistance at 80°C in the presence of a 30% by mass potassium hydroxide solution was insufficient. The separator of Comparative Example 2 was made only of a polypropylene-polyethylene nonwoven fabric, and did not contain a crosslinked body obtained by a curing reaction of any of the above (a) to (d). The separator of Comparative Example 2 was made only of a nonwoven fabric, so it was prone to absorb electrolyte, and although the ionic resistance was low, the water permeability was 300 mL / min cm ２ The separator of Comparative Example 3 contains the compound represented by formula (I-1), but the content of the constituent component derived from the compound represented by formula (I-1) is 40 mass %, which does not satisfy the requirements of the present invention. The separator of Comparative Example 3 has a water permeability of 300 mL / min cm ２ The separator of Comparative Example 3 showed a high increase in water permeability of 30% or more after 24 hours at 90°C, and was therefore poor in heat resistance and alkali resistance. ２ It exhibits low ionic resistance of less than 300 mL / min cm ２- They exhibited low water permeability of less than 1 bar. It is believed that the hydrophilic polyethyleneoxy structure in the dense structure allowed them to achieve both low water permeability and low ionic resistance. Furthermore, the separators of Examples 1 to 7 showed a low rate of increase in water permeability after 24 hours at 90°C, and were excellent in heat resistance and alkali resistance.

[0153] While the present invention has been described in connection with embodiments thereof, we do not intend to limit our invention to any of the details of the description unless otherwise specified, and believe that the claims should be construed broadly without departing from the spirit and scope of the invention as set forth in the appended claims.

[0154] This application claims priority based on Japanese Patent Application No. 2023-161728, filed in Japan on September 25, 2023, the contents of which are incorporated herein by reference.

Claims

1. A separator comprising a crosslinked product obtained by a curing reaction of any one of the following (a) to (d): (a) a compound represented by the following formula (I-1): In the formula (I-1), X １ and Y represents a group having at least one of an epoxy group and an oxetanyl group, and n is a number equal to or greater than 2. (b) A combination of a compound represented by the following formula (I-2) with at least one of a polyfunctional epoxy compound having no polyethyleneoxy group and a polyfunctional oxetane compound having no polyethyleneoxy group. In the formula (I-2), X ２ represents a hydrogen atom or a non-chain polymerizable organic group, and Y and n have the same meanings as Y and n in formula (I-1), respectively. (c) A compound represented by the following formula (II-1): In the formula (II-1), X ３ and Z represents a group having an allyl group, and n is a number of 2 or more. (d) A combination of a compound represented by the following formula (II-2) and a polyfunctional allyl compound having no polyethyleneoxy group: In the formula (II-2), X ４ represents a hydrogen atom or a non-chain polymerizable organic group. Z and n are respectively the same as Z and n in formula (II-1). However, when the crosslinked body is a crosslinked body obtained by a curing reaction of (a), the content of the component derived from the compound represented by formula (I-1) in the crosslinked body is 50% by mass or more, when the crosslinked body is a crosslinked body obtained by a curing reaction of (b), the content of the component derived from the compound represented by formula (I-2) in the crosslinked body is 50% by mass or more, when the crosslinked body is a crosslinked body obtained by a curing reaction of (c), the content of the component derived from the compound represented by formula (II-1) in the crosslinked body is 50% by mass or more, and when the crosslinked body is a crosslinked body obtained by a curing reaction of (d), the content of the component derived from the compound represented by formula (II-2) in the crosslinked body is 50% by mass or more.

2. The separator according to claim 1, wherein the curing reaction is a cationic polymerization reaction of (a) or (b).

3. The separator according to claim 2, wherein the cationic polymerization reaction is a reaction using at least one of a sulfonium salt and an iodonium salt as an acid generator.

4. The separator according to claim 3, wherein the cationic polymerization reaction is a reaction using a photosensitizer represented by the following formula (1): In formula (1), R １ and R ２ represents an alkyl group.

5. The separator according to any one of claims 1 to 4, wherein the crosslinked product is a crosslinked product obtained by a curing reaction of (a).

6. The separator according to claim 5, wherein the curing reaction is carried out in the presence of an oxetane compound having no polyethyleneoxy group.

7. The separator according to any one of claims 1 to 4, wherein the crosslinked body is a crosslinked body obtained by a curing reaction of (b).

8. The separator according to claim 7, wherein the curing reaction is carried out in the presence of a monofunctional oxetane compound having no polyethyleneoxy group.

9. The separator according to any one of claims 1 to 4, wherein the separator further comprises a porous support.

10. The separator according to any one of claims 1 to 4, for use as a diaphragm for separating an anode and a cathode in the electrolysis of water.

11. The separator according to claim 10, wherein the electrolysis of water is alkaline water electrolysis.

12. A curable composition comprising the following (a) or (b) and a photoacid generator or a thermal acid generator: (a) a compound represented by the following formula (I-1): In the formula (I-1), X １ and Y represents a group having at least one of an epoxy group and an oxetanyl group, and n is a number equal to or greater than 2. (b) A combination of a compound represented by the following formula (I-2) with at least one of a polyfunctional epoxy compound having no polyethyleneoxy group and a polyfunctional oxetane compound having no polyethyleneoxy group. In the formula (I-2), X ２ represents a hydrogen atom or a non-chain polymerizable organic group. Y and n are respectively defined as Y and n in formula (I-1). However, when the curable composition contains (a), the content of the compound represented by formula (I-1) in the solid content of the curable composition is 50 mass% or more, and when the curable composition contains (b), the content of the compound represented by formula (I-2) in the solid content of the curable composition is 50 mass% or more.

13. The curable composition according to claim 12, which contains the photoacid generator and a photosensitizer represented by the following formula (1): In formula (1), R １ and R ２ represents an alkyl group.

14. A method for producing a separator, comprising subjecting the curable composition according to claim 12 or 13 to a curing reaction to obtain a crosslinked product.

15. A method for producing the separator according to claim 14, comprising subjecting the curable composition according to claim 12 or 13, while impregnated into a porous support, to a curing reaction to obtain a composite of the porous support and the crosslinked body.

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