Photocurable composition for sealing material of lithium ion secondary battery

Abstract

This photocurable composition for a lithium ion secondary battery sealing material contains, at a specific ratio, component (A): a compound having two (meth) acryloyl groups and having a polybutadiene and / or hydrogenated polybutadiene skeleton in one molecule and a number average molecular weight of 1000 or more; component (B-1): a monofunctional (meth) acrylate having an alkyl group or an alkenyl group and having an ester residue having 10 to 30 carbon atoms Component (B-2): a monofunctional (meth) acrylate having an alicyclic hydrocarbon group and / or an aromatic hydrocarbon group and having an ester residue having 5 to 30 carbon atoms Component (C): a photo-radical polymerization initiator.

Description

Technical Field

[0001] The present invention relates to a photocurable composition for a sealing material of a lithium ion secondary battery, and can be preferably used for manufacturing a lithium ion secondary battery.

[0002] It should be noted that in the specification, acrylate and / or methacrylate are represented as (meth)acrylate, acryloyl and / or methacryloyl are represented as (meth)acryloyl, and acrylic acid and / or methacrylic acid are represented as (meth)acrylic acid. Background Art

[0003] In recent years, in order to solve various problems led by environmental problems, the popularization of electric vehicles has been expected.

[0004] In the popularization of electric vehicles, in addition to low price, horsepower comparable to gasoline vehicles and a cruising range are required. Therefore, the development of secondary batteries is being actively promoted. Among them, a lithium ion secondary battery that is lightweight and can achieve a high energy density is preferably used as a high-output power source for driving vehicles such as electric vehicles (EVs), plug-in hybrid vehicles (PHVs), and hybrid vehicles (HVs), and it is expected that the demand will increase in the future.

[0005] Under such circumstances, various studies have been conducted to improve the performance of lithium ion secondary batteries.

[0006] As one of them, there is a so-called bipolar battery (Non-Patent Document 1) in which one surface of a current collector is a positive electrode and the other surface is a negative electrode. If bipolar batteries are stacked, a compact and high-voltage battery can be manufactured. Such a battery cell of a bipolar battery has a planar structure, and a sealing material for sealing an electrolytic solution is required at its end.

[0007] Various studies have been conducted on a sealing material for sealing the end of a bipolar lithium ion secondary battery.

[0008] For example, in Patent Document 1, the structure of a bipolar lithium ion secondary battery is illustrated. As a sealing member, there is no particular limitation as long as it has adhesiveness to a positive electrode and a negative electrode current collector and durability against an electrolytic solution, but it is described that a polymer material, particularly a thermosetting resin, is preferable (Patent Document 1:

[0047] ).

[0009] In Patent Document 2, the structure of a bipolar lithium ion secondary battery is illustrated. As a sealing member, a heat-sealable film is shown. In addition, it is shown that wrinkles of a resin current collector generated by heat sealing can be solved by a reinforcing member.

[0010] Patent Document 3 discloses a photocurable composition that can be suitably used as a material for fixing and sealing the side surface of an all-solid battery having a laminated electrode body.

[0011] Patent Document 4 discloses a radiation-curable coating composition, which can also be suitably used as an electrode protective agent for lithium-ion batteries.

[0012] Prior Art Documents

[0013] Patent Documents

[0014] Non-Patent Document 1: Nikkei Electronics, September 2017 issue, pages 13 - 15

[0015] Patent Document 1: Japanese Patent Laid-Open No. 2017 - 103219

[0016] Patent Document 2: Japanese Patent Laid-Open No. 2017 - 16825

[0017] Patent Document 3: Japanese Patent Laid-Open No. 2022 - 15477

[0018] Patent Document 4: Pamphlet of International Publication No. 2013 / 157624 Summary of the Invention

[0019] Problems to be Solved by the Invention

[0020] However, as a sealing material for conventional bipolar lithium-ion secondary batteries, there are various problems.

[0021] The thermosetting resin exemplified as a preferred material in Patent Document 1 requires at least several minutes before curing, and usually requires several minutes to several hours, so there are problems in mass productivity.

[0022] Although the heat-fusible film described in Patent Document 2 has the advantage of short-time adhesion, since heat is applied and it becomes high temperature, there is a problem of generating wrinkles. In this document, this problem is solved by a reinforcing member, but in this case, other problems such as the product structure or manufacturing process becoming complicated will occur.

[0023] In Patent Document 3, a photocurable composition suitable for fixing and sealing the side surface of an all-solid battery having a laminated electrode body is disclosed. By applying the photocurable composition, curing can be performed in a short time without heating, and mass productivity is improved.

[0024] However, since the all-solid battery exemplified here does not contain an electrolyte, it is not clear whether the photocurable composition listed here can be applied as a sealing material for a lithium-ion secondary battery containing an electrolyte.

[0025] Patent Document 4 discloses a photocurable coating composition that has excellent adhesion to aluminum foil (positive electrode foil). Even after being immersed in the solvent used in the electrolyte, its appearance and adhesion do not deteriorate, but the properties required for a sealing material are unknown. That is, the peel adhesion to the electrode substrate, the peel adhesion to the electrode substrate after immersion in the electrolyte, and the swelling rate of the cured product based on electrolyte immersion are not mentioned.

[0026] Therefore, the present inventors evaluated the composition disclosed in Patent Document 4 and found that the peel adhesion to aluminum foil (positive electrode foil) and / or copper foil (negative electrode foil) after solvent immersion may not be sufficient when used as a sealing material.

[0027] The present inventors conducted in-depth research to find a photocurable composition for a lithium-ion secondary battery sealing material that can be coated at room temperature and cured in a short time, has good peel adhesion to the electrode substrate before and after electrolyte immersion, and has a small swelling rate caused by electrolyte immersion.

[0028] Means for Solving the Problems

[0029] The present inventors conducted various studies to solve the above problems and found that a composition containing a compound having a polybutadiene and / or hydrogenated polybutadiene backbone and having two (meth)acryloyl groups with a specific molecular weight, a compound having one (meth)acryloyl group in one molecule containing two specific compounds (hereinafter referred to as "monofunctional (meth)acrylate"), and a photo radical polymerization initiator can be coated at room temperature and cured in a short time, has good peel adhesion to the electrode substrate before and after electrolyte immersion, and has a small swelling rate caused by electrolyte immersion, thus completing the present invention.

[0030] Hereinafter, the present invention will be described in detail.

[0031] Effects of the Invention

[0032] According to the composition of the present invention, it can be coated at room temperature and cured in a short time, has good peel adhesion to the electrode substrate before and after electrolyte immersion, and has a small swelling rate caused by electrolyte immersion. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A figure showing an example of a cross-sectional view of a bipolar lithium-ion secondary battery.

[0034] Figure 2 A figure showing an example of a method for manufacturing a lithium-ion secondary battery using the composition of the present invention.

[0035] Figure 3 A figure showing an example of a method for manufacturing a lithium-ion secondary battery using the composition of the present invention.

[0036] Description of Reference Numerals

[0037] 11 Current collector foil, 12 Positive electrode active material, 13 Separator, 14 Negative electrode active material, 21 Battery constituent material, 22 Dispenser, 23 Ultraviolet irradiation device Detailed Description of the Invention

[0038] The present invention is as follows.

[0039] [1] A photocurable composition for a sealing material of a lithium ion secondary battery, comprising:

[0040] Component (A): A compound having a polybutadiene and / or hydrogenated polybutadiene skeleton in one molecule and having two (meth)acryloyl groups with a number average molecular weight of 1000 or more,

[0041] Component (B): A monofunctional (meth)acrylate containing the following components (B-1) and (B-2) as essential components,

[0042] wherein, component (B-1): A monofunctional (meth)acrylate having an alkyl or alkenyl group with 10 to 30 carbon atoms in the ester residue, component (B-2): A monofunctional (meth)acrylate having an alicyclic hydrocarbon group and / or an aromatic hydrocarbon group with 5 to 30 carbon atoms in the ester residue, and

[0043] Component (C): A photo radical polymerization initiator;

[0044] Based on 100% by weight of the total curable components, it contains 10 to 80% by weight of component (A) and 20 to 90% by weight of component (B),

[0045] Based on 100% by weight of the total curable components, it contains 15 to 70% by weight of component (B-1), and based on 100% by weight of the total curable components, it contains 5 to 50% by weight of component (B-2),

[0046] Based on 100 parts by weight of the total curable components, it contains 0.1 to 20 parts by weight of component (C).

[0047] [2] The photocurable composition for a sealing material of a lithium ion secondary battery according to [1], wherein the above component (A) is a urethane (meth)acrylate having a number average molecular weight of 5000 to 50000.

[0048] [3] The photocurable composition for a sealing material of a lithium ion secondary battery according to [1] or [2], wherein the above component (B-1) contains a (meth)acrylic acid alkyl ester having a branched chain structure and 17 to 30 carbon atoms.

[0049] 〔4〕A method for manufacturing a lithium ion secondary battery, wherein after coating or injecting the photocurable composition for the lithium ion secondary battery sealant according to any one of the above 〔1〕~〔3〕 on the side surface of the constituent materials of the lithium ion secondary battery, light irradiation is performed on the coated surface or the injected surface.

[0050] 〔5〕A lithium ion secondary battery, wherein the side surface of the constituent materials of the lithium ion secondary battery is sealed with a cured product of the photocurable composition for the lithium ion secondary battery sealant according to any one of the above 〔1〕~〔3〕.

[0051] Hereinafter, the components (A)~(C), other components, the composition and the usage method will be described.

[0052] It should be noted that the specific compounds cited in the following description of the components (A)~(C) can be used alone or in combination of two or more.

[0053] 1. Component (A)

[0054] Component (A) is a compound having a polybutadiene-based skeleton and / or a hydrogenated polybutadiene-based skeleton in one molecule and having two or more (meth)acryloyl groups with a Mn of 1000 or more.

[0055] As the (meth)acryloyl group in component (A), it can be present in the side chain or at the terminal, preferably a compound having a (meth)acryloyl group at the terminal, and particularly preferably a compound having (meth)acryloyl groups at both terminals.

[0056] The Mn (number average molecular weight) of component (A) is 1000 or more, preferably 5000~50000, more preferably 10000~30000.

[0057] If a compound with a Mn of less than 1000 is used, the adhesion to the aluminum foil will decrease.

[0058] It should be noted that in the present invention, Mn (number average molecular weight) refers to the value obtained by converting the molecular weight measured by gel permeation chromatography (hereinafter referred to as "GPC") to polystyrene.

[0059] As component (A), oligomers in which a polybutadiene or hydrogenated polybutadiene skeleton is bonded to two or more (meth)acryloyl groups through a urethane bond [hereinafter referred to as "(A1)"], oligomers in which a polybutadiene or hydrogenated polybutadiene skeleton is bonded to two or more (meth)acryloyl groups through an ester bond [hereinafter referred to as "(A2)"], etc. can be cited.

[0060] As the component (A), (A1) and (A2) are preferred. From the viewpoint of excellent mechanical properties of the cured product, (A1) is preferred, and a urethane (meth)acrylate oligomer having two (meth)acryloyl groups is more preferred.

[0061] Furthermore, as the urethane (meth)acrylate oligomer having two (meth)acryloyl groups in (A1), a urethane (meth)acrylate oligomer obtained by reacting a polybutadiene diol or a hydrogenated polybutadiene diol (a) [hereinafter referred to as "compound (a)"], a diisocyanate compound (b) [hereinafter referred to as "compound (b)"], and a hydroxy group-containing (meth)acrylate (c) [hereinafter referred to as "compound (c)"] is preferred.

[0062] The Mn of compound (a) is preferably from 500 to 10,000, more preferably from 1000 to 10,000.

[0063] In the present invention, in addition to compound (a), other polyols other than compound (a) can be used as needed.

[0064] For example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexanedimethanol, and hydrogenated bisphenol A can be mentioned.

[0065] As compound (b), various compounds can be used as long as they have two isocyanate groups in one molecule.

[0066] Specifically, toluene diisocyanate, hydrogenated toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tolidine diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, and hydrogenated xylylene diisocyanate can be mentioned.

[0067] As compound (c), various compounds can be used as long as they are (meth)acrylates having a hydroxy group.

[0068] As specific examples, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, a caprolactone-modified product of 2-hydroxyethyl (meth)acrylate, and diglycidyl (meth)acrylate can be mentioned.

[0069] Among them, hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate are preferred.

[0070] As a specific example of (A2), an esterification reaction product of polybutadiene or hydrogenated polybutadiene having two or more hydroxyl groups and (meth)acrylic acid or (meth)acrylic acid halide, and a transesterification reaction product of polybutadiene or hydrogenated polybutadiene having two or more hydroxyl groups and (meth)acrylate can be cited.

[0071] Component (A) is commercially available. As specific examples of (A1), “TEA-1000” (polybutadiene-based urethane acrylate oligomer, Mn: about 3000) manufactured by Nippon Soda Co., Ltd., “TEAI-1000” (hydrogenated polybutadiene-based urethane acrylate oligomer, Mn: about 3000) manufactured by Nippon Soda Co., Ltd., “TE-2000” (polybutadiene-based urethane methacrylate oligomer) manufactured by Nippon Soda Co., Ltd., “CN9014” (polybutadiene-based urethane acrylate) manufactured by Sartomer Company, “CN301” (polybutadiene-based dimethacrylate) manufactured by Sartomer Company, “CN303” (polybutadiene-based dimethacrylate) manufactured by Sartomer Company, “CN307” (polybutadiene-based diacrylate) manufactured by Sartomer Company, etc. can be cited.

[0072] As a specific example of (A2), “BAC-45” (polybutadiene-based diacrylate, Mn: 5000) manufactured by Osaka Organic Chemical Industry Co., Ltd. etc. can be cited.

[0073] Among these compounds, from the viewpoint of good photocurability, “TEAI-1000”, “TEA-1000”, “CN9014”, “CN307” and “BAC-45” having an acryloyl group are preferred.

[0074] As component (A), a (meth)acrylate oligomer having a hydrogenated polybutadiene skeleton is preferred, and a urethane (meth)acrylate having a hydrogenated polybutadiene skeleton is more preferred.

[0075] Regarding the content ratio of component (A), when component (D) described later is included in the total amount of 100% by weight of component (A) and component (B), it needs to be 10 to 80% by weight, preferably 10 to 60% by weight, and particularly preferably 15 to 50% by weight in the total amount of 100% by weight of component (A), component (B) and component (D).

[0076] It should be noted that hereinafter, when component (A) and component (B) or component (D) described later are included, component (A), component (B) and component (D) are referred to as “curable components”.

[0077] If the content ratio of component (A) is less than 10% by weight, the swelling rate of the cured product after electrolyte impregnation increases, and the adhesion to the electrode foil after electrolyte impregnation decreases. On the other hand, if it exceeds 80% by weight, the adhesion of the cured product decreases.

[0078] 2. Component (B)

[0079] Component (B) is a monofunctional (meth)acrylate containing the following component (B-1) and component (B-2) as essential components.

[0080] Component (B-1): A monofunctional (meth)acrylate having an alkyl or alkenyl group with 10 to 30 carbon atoms in the ester residue

[0081] Component (B-2): A monofunctional (meth)acrylate having an alicyclic hydrocarbon group and / or an aromatic hydrocarbon group with 5 to 30 carbon atoms in the ester residue

[0082] Here, the description "ester residue" means the group represented by R after removing the ester bond from the structural part represented by -CO-O-R contained in the monofunctional (meth)acrylate.

[0083] Component (B-1) is a compound having an alkyl or alkenyl group with 10 to 30 carbon atoms (hereinafter, these groups are collectively referred to as "alkyl groups, etc.") and having 1 (meth)acryloyl group.

[0084] In component (B), examples of the ester residue having an alkyl group, etc. with 10 to 30 carbon atoms include an alkyl group, an alkenyl group, and a (poly)oxyalkylene group having an alkyl or alkenyl group, etc.

[0085] It should be noted that the "(poly)oxyalkylene group" means a group having 1 or 2 or more epoxy alkane units.

[0086] In component (B-1), a compound having 9 or less carbon atoms in the alkyl group, etc. has a problem that the swelling rate of the cured product after electrolyte impregnation increases. On the other hand, a compound having 31 or more carbon atoms in the alkyl group, etc. has a problem that the adhesion to the electrode foil decreases.

[0087] In component (B-1), examples of the compound having an alkyl group include (meth)acrylate decyl, (meth)acrylate lauryl, (meth)acrylate cetyl, (meth)acrylate heptadecyl, (meth)acrylate stearyl, (meth)acrylate isostearyl, and (meth)acrylate docosyl, etc., (meth)acrylate alkyl esters having an alkyl group with 10 to 30 carbon atoms.

[0088] Examples of the compound having an alkenyl group include (meth)acrylate 8-dodecenyl, (meth)acrylate 9-octadecenyl, etc.

[0089] Examples of the (poly)oxyalkylene group having an alkyl group or the like include a (poly)oxyalkylene group having an alkyl group.

[0090] Examples of the compound having a (poly)oxyalkylene group having an alkyl group include alkyl carbitol (meth)acrylates such as octadecyl carbitol (meth)acrylate.

[0091] The number of repetitions of the alkylene oxide unit in this case is preferably 1 to 8.

[0092] As the component (B-1), (meth)acrylic acid alkyl esters having a branched structure and 17 to 30 carbon atoms such as isostearyl (meth)acrylate are preferred.

[0093] The component (B-2) is a compound having 5 to 30 carbon atoms in the ester residue, having an alicyclic hydrocarbon group and / or an aromatic hydrocarbon group, and having 1 (meth)acryloyl group.

[0094] In the component (B-2), examples of the alicyclic hydrocarbon group having 5 to 30 carbon atoms include a cyclic alkyl group and a cyclic alkenyl group.

[0095] In addition, examples of the alicyclic hydrocarbon group and the aromatic hydrocarbon group may be a (poly)oxyethylene group having an alicyclic hydrocarbon group and a (poly)oxyethylene group having an aromatic hydrocarbon group.

[0096] The alicyclic hydrocarbon group and the aromatic hydrocarbon group may be a functional group further having an alkyl group in a part of the cyclic skeleton.

[0097] Among the compounds having an alicyclic hydrocarbon group in the component (B-2), examples of the compound having a cyclic alkyl group include (meth)acrylic acid cyclohexyl esters, (meth)acrylic acid isobornyl esters, (meth)acrylic acid dicyclopentyl esters, and (meth)acrylic acid tert-butylcyclohexyl esters, etc., (meth)acrylic acid esters having a cyclic alkyl group having 5 to 30 carbon atoms.

[0098] Examples of the compound having a cyclic alkenyl group include cyclohexenyl (meth)acrylate and dicyclopentenyl (meth)acrylate.

[0099] Examples of the compound having a (poly)oxyalkylene group having a cyclic alkyl group include (meth)acrylic acid dicyclopentyloxyethyl ester.

[0100] Examples of the monofunctional (meth)acrylate having an aromatic hydrocarbon group in the component (B-2) include aromatic monofunctional (meth)acrylates such as (meth)acrylic acid benzyl ester, (meth)acrylic acid phenoxyethyl ester, o-phenylphenoxy (meth)acrylate, and p-cumylphenol ethylene (meth)acrylate.

[0101] Examples of the compound having a (poly)oxyalkylene group containing an alkyl aromatic group include (meth)acrylates of nonylphenol ethylene oxide adducts and (meth)acrylates of nonylphenol ethylene oxide adducts, etc., (meth)acrylates of alkylphenol ethylene oxide adducts having an alkyl group with 4 to 20 carbon atoms.

[0102] As the repeating number of the oxyalkylene unit in this case, it is preferably 1 to 8.

[0103] As the component (B), it may contain a monofunctional (meth)acrylate [hereinafter referred to as “component (B-3) ”] other than the component (B-1) and the component (B-2), but it is preferably not contained.

[0104] Examples of the component (B-3) include: monofunctional (meth)acrylates having an alkyl group with 9 or less carbon atoms in the ester residue such as n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, and n-octyl (meth)acrylate; monofunctional (meth)acrylates having an alkenyl group with 9 or less carbon atoms in the ester residue such as pentenyl (meth)acrylate, butenyl (meth)acrylate, and hexenyl (meth)acrylate; monofunctional (meth)acrylates having a heterocycle such as tetrahydrofurfuryl (meth)acrylate; monofunctional (meth)acrylates having a hydroxyl group such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; (meth)acrylates containing an epoxy group such as glycidyl (meth)acrylate; monofunctional (meth)acrylates having a maleimide group such as (meth)acryloyloxyethyl hexahydrophthalimide; and monofunctional (meth)acrylates containing an alkoxy group such as 3-(meth)acryloyloxypropyl methyldimethoxysilane, 3-(meth)acryloyloxypropyl trimethoxysilane, 3-(meth)acryloyloxypropyl methyldiethoxysilane, and 3-(meth)acryloyloxypropyl triethoxysilane.

[0105] The content ratio of the component (B) needs to be set to 20 to 90% by weight, preferably 40 to 90% by weight, more preferably 50 to 85% by weight in the total 100% by weight of the curable components.

[0106] Furthermore, the content ratio of (B-1) is 15 to 70% by weight, preferably 30 to 70% by weight in the total 100% by weight of the curable components.

[0107] If the content ratio of the component (B-1) is less than 15% by weight, the swelling ratio of the cured product after electrolyte impregnation increases and the adhesion to the electrode foil after electrolyte impregnation decreases. On the other hand, if it exceeds 70% by weight, the adhesion of the cured product decreases.

[0108] Furthermore, the content ratio of (B-2) is 5 to 50% by weight, preferably 10 to 40% by weight, based on 100% by weight of the total amount of the curable components.

[0109] If the content ratio of the component (B-2) is less than 5% by weight, the swelling ratio of the cured product after electrolyte impregnation increases, and the adhesive force to the electrode foil after electrolyte impregnation decreases. On the other hand, if it exceeds 70% by weight, the adhesive force of the cured product decreases.

[0110] It is preferably free of the component (B-3), and when it is contained, it is preferably 8% by weight or less based on 100% by weight of the total amount of the curable components. By setting the content ratio to 8% by weight or less, the swelling ratio of the cured product after electrolyte impregnation can be reduced.

[0111] 3. Component (C)

[0112] The component (C) is a photo radical polymerization initiator.

[0113] The component (C) is a compound that generates radicals upon irradiation with active energy rays and initiates the polymerization of a compound having an ethylenically unsaturated group.

[0114] As specific examples of the component (C), there may be mentioned aromatic ketone compounds such as benzyl dimethyl ketal, benzil, benzoin, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, oligo[2-hydroxy-2-methyl-1-[4-1-(methylvinyl)phenyl]acetone, 2-hydroxy-1-[4-[4-(2-hydroxy-2-methylacryloyl)benzyl]phenyl]-2-methylpropan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)butan-1-one, 3,6-bis(2-methyl-2-morpholinopropionyl)-9-n-octylcarbazole, methyl benzoylformate, ethyl anthraquinone, phenanthraquinone and the like; benzophenone compounds such as benzophenone, 2-methylbenzophenone, 3-methylbenzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 4-(methylphenylthio)phenylphenylmethane, methyl-2-benzophenone, 1-[4-(4-benzoylphenylthio)phenyl]-2-methyl-2-(4-methylphenylsulfonyl)propan-1-one, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4-methoxy-4'-dimethylaminobenzophenone and the like; acylphosphine oxide compounds such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl)phenyl ethyl phosphonate, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and the like; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, 1-chloro-4-propylthioxanthone, 3-[3,4-dimethyl-9-oxo-9H-thioxanthon-2-yl-oxy]-2-hydroxypropyl-N,N,N-trimethylammonium chloride, fluothioxanthone and the like.

[0115] With respect to a total of 100 parts by weight of the curable components, the content ratio of the component (C) is 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight, more preferably 0.5 to 5 parts by weight. If the content ratio of the component (C) is less than 0.1 part by weight, the photocurability of the composition is reduced, and if it exceeds 20 parts by weight, the solvent resistance of the cured product after electrolyte impregnation is reduced.

[0116] 4. Other components

[0117] The composition of the present invention contains the above components (A), (B) and (C) as essential components, and various components commonly used as sealing materials can be incorporated.

[0118] For example, compounds having an ethylenically unsaturated group, compounds other than components (A) and (B) [hereinafter referred to as “component (D)”], fillers [hereinafter referred to as “component (E)”], photoacid generators, silane coupling agents, antioxidants, ultraviolet absorbers, light stabilizers, adhesion imparting agents, thiol compounds, plasticizers, fluorescent agents, pigments, dyes, dispersants and / or antistatic agents, etc. can be cited.

[0119] 1) Component (D)

[0120] Component (D) is a compound having an ethylenically unsaturated group and is a compound other than component (A) and component (B).

[0121] Examples of the ethylenically unsaturated group in component (D) include (meth)acryloyl group, (meth)acrylamide group, vinyl group, allyl group, etc. Among them, from the viewpoint of excellent copolymerizability with other components, (meth)acryloyl group is preferred.

[0122] As component (D), various compounds can be used as long as they are compounds having an ethylenically unsaturated group. For example, compounds having two (meth)acryloyl groups in one molecule [hereinafter referred to as “bifunctional (meth)acrylate”] and compounds having three or more (meth)acryloyl groups [hereinafter referred to as “trifunctional or higher (meth)acrylate”] can be cited.

[0123] Specific examples of bifunctional (meth)acrylate include di(meth)acrylates having a divalent alkyl group such as ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6 - hexanediol di(meth)acrylate, and nonanediol di(meth)acrylate; polyalkylene glycol di(meth)acrylates such as polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and polytetraethylene glycol di(meth)acrylate; di(meth)acrylates having an alicyclic group such as tricyclodecane dimethanol di(meth)acrylate; di(meth)acrylate of an ethylene oxide adduct of bisphenol A; and urethane di(meth)acrylate, etc.

[0124] Examples of urethane di(meth)acrylate include urethane (meth)acrylate not having a polybutadiene and / or hydrogenated polybutadiene skeleton, etc.

[0125] As the (meth)acrylate having three or more functional groups, specifically, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tris(2-(meth)acryloyloxyethyl) isocyanurate, etc. can be mentioned.

[0126] As the content ratio of the component (D), in 100% by weight of the curable components, it is preferably 8% by weight or less, more preferably 0 to 5% by weight.

[0127] 2) Component (E)

[0128] The component (E) is a filler.

[0129] As a preferred example of the component (E), metal oxides such as silica and alumina, and polymer particles such as polyethylene particles, polypropylene particles, crosslinked acrylic particles, and crosslinked polystyrene particles can be mentioned.

[0130] The preferred particle size of the particles is 0.1 to 200 μm, more preferably 1 to 100 μm.

[0131] By incorporating the component (E), the moisture permeability of the cured product and the electrolyte permeability can be reduced. In addition, the screen printing property can be improved. However, when the content ratio of the filler is too high, the printability may sometimes decrease, so it is preferably contained in a preferred content ratio. On the other hand, in the case of coating by inkjet, spraying, etc., it is preferably free of the component (E), or limited to a very small amount.

[0132] From the above, the preferred content ratio of the component (E) is 0 to 60% by weight in 100% by weight of the composition.

[0133] 5. Photo-curable composition for a lithium ion secondary battery sealing material

[0134] The present invention relates to a photo-curable composition for a lithium ion secondary battery sealing material, which contains the above components (A) to (C) and contains them in the above ratios.

[0135] As the ratio of the curable components in the composition, in 100% by weight of the composition, it is preferably 40 to 99.9% by weight, more preferably 50 to 99.5% by weight.

[0136] In addition, in the case of containing the component (E), as the total content ratio of the curable components and the component (E), in 100% by weight of the composition, it is preferably 80 to 99.9% by weight, more preferably 90 to 99.9% by weight, and further preferably 95 to 99.9% by weight.

[0137] The composition can be produced by stirring and mixing the above components (A) to (C) according to a conventional method as required.

[0138] In this case, heating may be performed as necessary. The heating temperature may be appropriately set depending on the components used, the substrate, the purpose, etc., and is preferably 30 to 80°C.

[0139] The viscosity of the composition may be adjusted according to the coating method, and is preferably 10 to 100,000 mPa·s, more preferably 100 to 10,000 mPa·s at 25°C.

[0140] How to use

[0141] The method of using the composition of the present invention may be a conventional method, and examples thereof include a method comprising the steps of applying or injecting the composition of the present invention onto a material constituting a lithium ion secondary battery, and irradiating the applied or injected composition with light to cure it.

[0142] Examples of materials constituting a lithium ion secondary battery include a current collector foil, a positive electrode active material, a negative electrode active material, a separator, and an electrolyte solution.

[0143] Examples of the current collector foil include aluminum and copper.

[0144] The active material may be appropriately selected according to the type of battery.

[0145] For example, examples of the positive electrode active material include lithium-transition metal composite oxides, lithium-transition metal phosphate compounds, and lithium-transition metal sulfate compounds.

[0146] In addition, examples of negative electrode active materials include metals such as Si and Sn; TiO, Ti 2 O 3 、TiO 2 、SiO 2 , SiO and SnO 2 Metal oxides such as lithium and transition metals; composite oxides of lithium and transition metals; Li-Pb alloys, Li-Al alloys; and carbon materials such as graphite, carbon black, activated carbon, carbon fiber, coke, soft carbon and hard carbon.

[0147] Examples of the diaphragm include microporous membrane films made of polyolefins such as polyethylene and polypropylene, multilayer films of porous polyethylene films and polypropylene, non-woven fabrics composed of polyester fibers, aromatic polyamide fibers, glass fibers, etc., and films having ceramic particles such as silica, alumina, and titanium dioxide attached to their surfaces.

[0148] As the electrolyte, ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, etc. can be cited, and a mixed solution thereof can also be used.

[0149] As the coating and injection method, any conventionally known method can be used, and examples thereof include dispenser, jet dispenser, screen printing, natural coater, knife coater, floating knife, doctor roll, doctor blade, spraying, dipping, kiss roll, squeeze roll, reverse roll, air knife, curtain coater, comma coater, gravure coater, microgravure coater, die coater, and curtain coater.

[0150] As the light, visible light and ultraviolet light can be cited, but ultraviolet light is preferred because a cheap device can be used.

[0151] As the light source for curing with ultraviolet light, various light sources can be used. For example, a pressurized or high-pressure mercury lamp, a metal halide lamp, a xenon lamp, an electrodeless discharge lamp, a carbon arc lamp, and an LED can be cited. Among them, a high-pressure mercury lamp, a metal halide lamp, and an LED are preferred. The irradiation amount of ultraviolet light in the UV-A region (around 365 nm) is preferably 50 to 5000 mJ / cm 2 , more preferably 100 to 3000 mJ / cm 2 . The illuminance of ultraviolet light in the UV-A region (around 365 nm) is preferably 10 to 5000 mW / cm 2 , more preferably 100 to 2000 mW / cm 2 .

[0152] Use Figures 1 to 3 Specific examples of the usage method of the composition of the present invention will be described.

[0153] Figure 1 is an example of a cross-sectional view of a bipolar lithium ion secondary battery.

[0154] In Figure 1 configuration, a positive electrode active material 12, a separator 13, and a negative electrode active material 14 are arranged in a space sandwiched by a current collector foil 11. An electrolyte exists in the space of the positive electrode active material 12, the separator 13, and the negative electrode active material 14. In order to prevent the leakage of the electrolyte, the outer peripheral portion is sealed by a sealing member 15 which is a cured product of the composition.

[0155] The composition of the present invention is particularly suitable as a sealing material for a lithium ion secondary battery in such a form. In addition, Figure 1 For easy understanding, an example of two layers is shown, but in fact, a structure in which dozens of layers are overlapped may also be used.

[0156] Next, based on Figure 2An example of a method for manufacturing a lithium ion secondary battery using the composition of the present invention is described.

[0157] Figure 2 An example is shown in which, after laminating the battery constituent materials, coating is performed from the side in such a manner as to fill the composition of the present invention, and light irradiation is performed from the side.

[0158] Figure 2 (1) of indicates the step of laminating the battery constituent materials ( Figure 2 21 of), and then performing coating from the side in such a manner as to fill the composition of the present invention.

[0159] As a specific example of the coating method at this time, a dispenser, an ejection dispenser, inkjet, spraying, etc. can be cited. Figure 2 (1) of shows an example of using a dispenser 22.

[0160] Figure 2 (2) of indicates the step of irradiating ultraviolet rays (UV) from the side with an ultraviolet ray irradiation device 23 to cure the composition after coating the composition.

[0161] In the case of the above steps, the electrolyte can be injected into the interior through a syringe or the like after curing the composition. In the hole of the injection port generated when inserting the syringe, as long as the composition of the present invention is injected again from the hole using a dispenser or the like and photocured, the hole of the injection port can be sealed.

[0162] Alternatively, the composition may be coated on three sides of the four sides and cured, and the electrolyte may be injected from the open side in a state where one side is open. After injecting a predetermined amount of the electrolyte, if the composition is coated on the last side and cured, all four sides can be sealed.

[0163] In addition, based on Figure 3 An example of a method for manufacturing a lithium ion secondary battery using the composition of the present invention by a method different from the above is described.

[0164] Figure 3 An example of a method for manufacturing a lithium ion secondary battery by coating the composition and curing it during the process of laminating the battery constituent materials is shown.

[0165] First, as shown in 31, a current collector foil coated with an active material (positive electrode active material 12 or negative electrode active material 14) at the central portions of both sides is prepared.

[0166] Next, as shown in 32, the composition of the present invention (15') is coated on the outer peripheral portion thereof. As the coating method, screen printing or a dispenser is preferred.

[0167] Next, as shown in 33, the separator 13 is covered, and as shown in 34, ultraviolet rays (UV) are irradiated thereon through the ultraviolet irradiation device 23. The separator 13 is mostly made of a polyolefin material and is preferably used because it transmits ultraviolet rays.

[0168] Next, as shown in 35, the composition (15') of the present invention is coated on the peripheral portion, and as shown in 36, ultraviolet rays are irradiated thereon through the ultraviolet irradiation device 23 to cure it.

[0169] Finally, as shown in 37, the current collector foil coated with the active material (positive electrode active material 12 or negative electrode active material 14) is laminated on the central portions of both sides.

[0170] Here, when the composition has adhesiveness, it can be bonded by applying pressure at room temperature. When it does not have adhesiveness, pressure can be applied with a press at about 60 to 100 °C to bond it. The temperature at this time is lower than that of the heat-sealable sealing material, so wrinkles and warping caused by thermal expansion can be suppressed.

[0171] By repeating the above operations (31 to 37), the laminate shown in Figure 1 can be manufactured.

[0172] The electrolyte can be injected by the same method as described in Figure 2 In addition, ultraviolet rays can also be irradiated between 32 and 33, and the electrolyte can be injected before laminating the separator 13 and before laminating the electrode foil of 37.

[0173] Examples

[0174] Examples and comparative examples are listed below to more specifically illustrate the present invention. It should be noted that "parts" in the following examples refer to parts by weight, and "%" refers to wt%.

[0175] Production Example (Production of Urethane Acrylate)

[0176] 1) Production Example 1 [Production of Bifunctional Urethane Acrylate Having a Hydrogenated Polybutadiene Skeleton]

[0177] In a 3 L four-necked detachable flask, 962 g (0.48 mol as hydroxyl group) of GI-3000 manufactured by Nippon Soda Co., Ltd., which is a hydrogenated polybutadiene having hydroxyl groups at both ends (hydroxyl value 28.0 mg KOH / g, Mn about 4000), 0.75 g of 2,6-di-t-butyl-p-cresol, and 448 g of isobornyl acrylate (hereinafter referred to as "IBXA") were charged, and a stirrer was installed and stirred and mixed to dissolve them.

[0178] A thermometer, a gas inlet tube, a dropping funnel, and a reflux condenser were installed in the flask. While stirring, a mixed gas of oxygen and nitrogen (5% oxygen) was bubbled, and the temperature was further raised to 50 °C. After dissolving 0.03 g of iron acetylacetonate as a catalyst in the solution, 66.6 g of isophorone diisocyanate (0.60 mol as isocyanate group) was added from the dropping funnel. After stirring and mixing at 80 °C for 2 hours, 17.3 g of 4-hydroxybutyl acrylate (hereinafter referred to as "HBA") (0.12 mol as hydroxyl group) was added and reacted for 5 hours. The disappearance of the isocyanate group was confirmed by IR spectrum, and the synthesis was completed.

[0179] The obtained product was a mixture containing 70% of urethane acrylate having a hydrogenated polybutadiene backbone (hereinafter referred to as "PUA-1") and 30% of IBXA as a diluent monomer.

[0180] The obtained product was analyzed by GPC, and as a result, the peak of the PUA-1 component could be confirmed in a form distinguishable from the monomer components. The polystyrene-converted molecular weight of the PUA-1 component was 19,000 in terms of Mn and 34,500 in terms of Mw.

[0181] 2) Production Example 2 [Production of bifunctional urethane acrylate having a hydrogenated polybutadiene backbone]

[0182] The same procedure as in Production Example 1 was carried out except that IBXA in Production Example 1 was changed to isostearyl acrylate (hereinafter referred to as "ISTA"), and a mixture containing 70% of PUA-1 and 30% of ISTA was obtained.

[0183] 3) Production Example 3 [Production of bifunctional acrylate obtained by directly acryloylating hydrogenated polybutadiene having hydroxyl groups at both ends]

[0184] 571.9 g (0.70 mol as hydroxyl group) of GI-1000 manufactured by Nippon Soda Co., Ltd., which is hydrogenated polybutadiene having hydroxyl groups at both ends (hydroxyl value 68.7 mg KOH / g, Mn about 1600), 60.5 g of acrylic acid, 632.4 g of heptane, and 12.6 g of p-toluenesulfonic acid monohydrate were charged into a 3 L separable flask, and a stirrer was installed and stirred and mixed to dissolve them.

[0185] A thermometer, a gas inlet tube, a dropping funnel, and a reflux condenser were installed in the flask. While stirring, a mixed gas of oxygen and nitrogen (5% oxygen) was blown in, and the mixture was further refluxed in an oil bath at 120 °C for 2 hours.

[0186] Transfer the solution to a separatory funnel and perform three washings with pure water. Add 0.012 g of 4-methoxyphenol as a polymerization inhibitor, stir at 80 °C while blowing in dry air, and slowly remove it by vacuum distillation. Raise the oil bath temperature to 85 °C and stir under reduced pressure at 10 Torr until no bubbles flow out of the solution, thereby synthesizing a difunctional acrylate (hereinafter referred to as GI-AA) obtained by directly acryloylating the hydrogenated polybutadiene with hydroxyl groups at both ends.

[0187] The molecular weight of GI-AA is 3000 in terms of Mn and 4200 in terms of Mw.

[0188] 2. Examples 1 to 7, Comparative Examples 1 to 10

[0189] 1) Preparation of a photocurable composition for a lithium-ion secondary battery sealing material

[0190] Mix the following components shown in Tables 1 and 2 in the proportions shown, and stir and mix them by a conventional method to obtain a photocurable composition for a lithium-ion secondary battery sealing material.

[0191] In the preparation of the composition, heat it to about 80 °C as needed.

[0192] [Table 1]

[0193]

[0194] [Table 2]

[0195]

[0196] In addition, the parts by weight of PUA-1 in the table represent the parts by weight of the urethane acrylate component contained only in the product of Preparation Example 1 or Preparation Example 2. In addition, the parts by weight of component (B) include the component (B) contained in the product of Preparation Example 1, and component (B) represents the total parts by weight of the component (B) contained in the product of Preparation Example 1 and the component (B) added later.

[0197] The numbers in Tables 1 and 2 represent parts by weight. In addition, the abbreviations in Tables 1 and 2 have the following meanings.

[0198] ◆ Component (A)

[0199] PUA-1: A difunctional urethane acrylate having a hydrogenated polybutadiene skeleton. The urethane acrylate component contained in the products of Preparation Example 1 and Preparation Example 2.

[0200] TEAI: A difunctional urethane acrylate having a hydrogenated polybutadiene skeleton (TEAI-1000 manufactured by Nippon Soda Co., Ltd.) (Mn: 3200, Mw: 6100)

[0201] GI-AA: A difunctional acrylate obtained by directly acryloylating hydrogenated polybutadiene with hydroxyl groups at both ends. The product of Production Example 3.

[0202] ◆ Component (B-1)

[0203] LA: Lauryl acrylate (LA manufactured by Osaka Organic Chemical Industry Co., Ltd.)

[0204] ISTA: Isostearyl acrylate (ISTA manufactured by Osaka Organic Chemical Industry Co., Ltd.)

[0205] STA: Stearyl acrylate (STA manufactured by Osaka Organic Chemical Industry Co., Ltd.)

[0206] ◆ Component (B-2)

[0207] IBXA: Isobornyl acrylate (IBXA manufactured by Osaka Organic Chemical Industry Co., Ltd.)

[0208] FA-513: Dicyclopentyl acrylate (FANCRYL FA-513AS manufactured by Showa Denko Materials Co., Ltd.)

[0209] M-111: Acrylate of 1-mole adduct of ethylene oxide to nonylphenol. ARONIX M-111 manufactured by Toagosei Co., Ltd.

[0210] ◆ Component (B-3)

[0211] HBA: 4-Hydroxybutyl acrylate (HBA manufactured by Osaka Organic Chemical Industry Co., Ltd.)

[0212] ◆ Component (C)

[0213] ONE: An α-hydroxyalkyl phenyl ketone type photoinitiator (ESACURE ONE manufactured by IGM Resins B.V.)

[0214] O-184: 1-Hydroxy-cyclohexyl-phenyl-ketone (Omnirad 184 manufactured by IGM Resins B.V.)

[0215] O-651: 2,2-Dimethoxy-1,2-diphenylethan-1-one (Omnirad 651 manufactured by IGM Resins B.V.)

[0216] ◆ Component (D)

[0217] HX-A: 1,6-Hexanediol diacrylate (Light Acrylate HX-A manufactured by Kyoeisha Chemical Co., Ltd.)

[0218] NP-A: Neopentyl glycol diacrylate (Light Acrylate NP-A manufactured by Kyoeisha Chemical Co., Ltd.)

[0219] UN-9200A: A difunctional urethane acrylate having a polycarbonate backbone and not having polybutadiene and hydrogenated polybutadiene backbones (Art Resin UN-9200A manufactured by Negami Kogyo Co., Ltd.)

[0220] UN-6301: A difunctional urethane acrylate having a polyether backbone urethane acrylate and not having polybutadiene and hydrogenated polybutadiene backbones (Art Resin UN-6301 manufactured by Negami Kogyo Co., Ltd.)

[0221] UC-203: An esterified product of an adduct of maleic anhydride to polyisoprene and 2-hydroxyethyl acrylate (UC-203 manufactured by Kuraray Co., Ltd.)

[0222] 2) Evaluation of the composition

[0223] Using the composition obtained above, the initial peel strength, the peel strength after electrolyte solvent impregnation, and the swelling after electrolyte solvent impregnation were evaluated according to the following method.

[0224] These results are shown in Tables 1 and 2.

[0225] (1) Initial peel strength

[0226] The composition obtained above was poured into a silicone frame mold with a thickness of 0.5 mm provided on a metal foil (an aluminum foil with a thickness of 25 μm made by UACJ Co., Ltd. and a low-roughness rolled copper foil with a thickness of 35 μm made by Fukuda Metal Foil Powder Industry Co., Ltd.). As a substrate that adheres stronger than the metal foil, it was laminated with an easily adherent PET film (Lumirror A4360 made by Toray Industries, Inc.) and photocured. The curing conditions used an LED of 365 nm (a surface-type LED irradiator made by CCS Co., Ltd.), and it was irradiated from the PET film side for 5 seconds with an illuminance of 1000 mW / cm 2 (measured with an illuminometer C12684 made by Hamamatsu Photonics K.K.). The cured sample was cut into strips with a width of 10 mm, the PET film side was adhered to a metal plate with double-sided tape, the metal foil was bent at 180° and slightly peeled, and the 180° peel strength was measured using Instron 5564 (made by Instron Japan Co., Ltd.). The tensile speed was 60 mm / s.

[0227] If the measured value is 1 N / cm or less, it is marked as ×, if it is 1 N / cm to 5 N / cm, it is marked as 〇, and if it is 5 N / cm or more, it is marked as ◎.

[0228] (2) Peel strength after electrolyte solvent impregnation

[0229] In the same manner as (1), a cured product in the form of a strip with a width of 10 mm was produced and immersed in a sufficient amount of EC / DEC = 3 / 7 (weight ratio). It should be noted that "EC" refers to ethylene carbonate and "DEC" refers to diethyl carbonate.

[0230] After standing at 23°C for 24 hours, the cured product was taken out, the droplets on the surface were removed, and then the peel strength was measured immediately in the same manner as (1).

[0231] If the measured value of the peel strength is 1 N / cm or less, it is marked as ×; if it is between 1 N / cm and 5 N / cm, it is marked as 〇; if it is 5 N / cm or more, it is marked as ◎.

[0232] (3) Swelling ratio after immersion in the electrolyte solvent

[0233] The composition obtained above was cast into a silicone mold with a thickness of 1 mm cut into any size. To eliminate the polymerization inhibition caused by oxygen, it was laminated with a 75-μm-thick silicone-treated demolding PET film (HTA manufactured by Fujimori Kogyo Co., Ltd.) and photocured. The curing conditions used an LED with a wavelength of 365 nm (surface-type LED irradiator manufactured by CCS Co., Ltd.), and irradiated from both sides for 5 seconds each with an illuminance of 1000 mW / cm 2 (measured with an illuminometer C12684 manufactured by Hamamatsu Photonics K.K.). Then, the PET film was peeled off to obtain a cured product. After measuring the initial weight of the cured product to four decimal places, it was immersed in a sufficient amount of EC / DEC = 3 / 7 (weight ratio). After standing at 23°C for 24 hours, the cured product was taken out, the droplets on the surface were removed, and the weight was measured immediately. The weight increase after immersion was evaluated as the swelling ratio relative to the initial weight.

[0234] In addition, if the swelling ratio is less than 30%, it is marked as ◎; if it is between 30% and 50%, it is marked as 〇; if it is 50% or more, it is marked as ×.

[0235] 3) Evaluation results

[0236] From the results in Table 1, it can be seen that the compositions of the present invention are excellent in both the initial peel strength and the peel strength after immersion in the electrolyte solvent with respect to aluminum and copper. Furthermore, the swelling ratio after immersion in the electrolyte solvent is small.

[0237] In contrast, from the results in Table 2, the compositions of the comparative examples without the (B-1) component are as follows. The composition of Comparative Example 1 showed a significant decrease in both the initial peel strength and the peel strength after immersion in the electrolyte solvent with respect to aluminum. The compositions of Comparative Example 5 showed a significant decrease in both the initial peel strength and the peel strength after immersion in the electrolyte solvent with respect to aluminum and copper. The composition of Comparative Example 6 had no problem with the initial peel strength with respect to aluminum and copper, but the peel strength after immersion in the electrolyte solvent decreased significantly, and the swelling ratio after immersion in the electrolyte solvent became large.

[0238] The compositions of Comparative Examples 2 to 4 that do not contain the (B-2) component show a significant decrease in the initial peel strength with respect to aluminum and copper and the peel strength after impregnation with the electrolyte solvent.

[0239] The compositions of the comparative examples that do not contain the (A) component are as described below. The compositions of Comparative Examples 7 and 8 show a slight decrease in the initial peel strength with respect to aluminum and copper, a significant decrease in the peel strength after impregnation with the electrolyte solvent, and furthermore, an increase in the swelling rate after impregnation with the electrolyte solvent. The composition of Comparative Example 9 shows a significant decrease in the initial peel strength with respect to aluminum and copper and the peel strength after impregnation with the electrolyte solvent. The composition of Comparative Example 10 has no problem with the initial peel strength with respect to aluminum and copper, but shows a significant decrease in the peel strength after impregnation with the electrolyte solvent.

[0240] Industrial availability

[0241] The present invention relates to a photocurable composition for a sealing material of a lithium ion secondary battery, and can be preferably used for the manufacture of a lithium ion secondary battery.

Claims

1. A photocurable composition for a sealing material of a lithium ion secondary battery, comprising: Component (A): A compound having 2 (meth)acryloyl groups with a polybutadiene and / or hydrogenated polybutadiene backbone in 1 molecule and a number average molecular weight of 1000 or more, Component (B): A compound having 1 (meth)acryloyl group in 1 molecule (hereinafter referred to as "monofunctional (meth)acrylate") containing the following Component (B-1) and Component (B-2) as essential components, wherein, Component (B-1): A monofunctional (meth)acrylate having an alkyl or alkenyl group with 10 to 30 carbon atoms in the ester residue, Component (B-2): A monofunctional (meth)acrylate having 5 to 30 carbon atoms in the ester residue and having an alicyclic hydrocarbon group and / or an aromatic hydrocarbon group, Component (C): A photo radical polymerization initiator; In the total 100% by weight of the curable components, 10 to 80% by weight of Component (A) and 20% to 90% by weight of Component (B) are contained, 15 to 70% by weight of Component (B-1) is contained relative to the total 100% by weight of the curable components, 5 to 50% by weight of Component (B-2) is contained relative to the total 100% by weight of the curable components, and 0.1 to 20 parts by weight of Component (C) is contained relative to 100 parts by weight of the total curable components.

2. The photocurable composition for a sealing material of a lithium ion secondary battery according to claim 1, wherein, The Component (A) is a urethane (meth)acrylate having a number average molecular weight of 5000 to 50000.

3. The photocurable composition for a sealing material of a lithium ion secondary battery according to claim 1 or 2, wherein, The Component (B-1) includes a (meth)acrylic acid alkyl ester having a branched structure and 17 to 30 carbon atoms.

4. A method for manufacturing a lithium ion secondary battery, wherein, After coating or injecting the photocurable composition for a sealing material of a lithium ion secondary battery according to any one of claims 1 to 3 on the side surface of the constituent materials of the lithium ion secondary battery, light irradiation is performed on the coated surface or the injected surface.

5. A lithium ion secondary battery, wherein, The side surface of the constituent materials of the lithium ion secondary battery is sealed with a cured product of the photocurable composition for a sealing material of a lithium ion secondary battery according to any one of claims 1 to 3.

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