Energy storage element

Abstract

To provide an energy storage element comprising an adhesive tape that can be used to secure electrode members, exhibits sufficient adhesive strength even at high temperatures (e.g., 200°C to 300°C), and has excellent heat resistance with suppressed dimensional changes; [Solution] An energy storage element according to an embodiment of the present invention comprises a winding body formed by winding a plurality of thin film electrodes, an adhesive tape for securing the winding body, and an electrolyte, wherein the adhesive tape comprises a base material and an adhesive layer disposed on at least one side of the base material, the base material comprises polyphenylene sulfide, and the adhesive layer comprises an acrylic polymer as a base polymer, an isocyanate crosslinking agent, and a tackifying resin, the acrylic polymer comprises a specific amount of constituent units derived from C5-15 acrylic monomer.

Description

Technical Field

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[0001] The present invention relates to a power storage element.

Background Art

[0002] Generally, an aluminum electrolytic capacitor includes an electrode member formed by winding an anode and a cathode laminated via a separator, and an outer can for hermetically storing the electrode member together with an electrolytic solution. At the outermost end portion of such an electrode member, that is, at the winding end portion, an adhesive tape is attached to maintain the wound state.

[0003] The aluminum electrolytic capacitor is exposed to high temperatures in the reflow process. In recent years, with the increasing density of electronic substrates that require aluminum electrolytic capacitors, the heat treatment tends to be at higher temperatures.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] <000,0030 The present invention has been made to solve the above conventional problems, and an object thereof is to provide an adhesive tape that can be used for winding an electrode member, exhibits sufficient adhesive force even at high temperatures (for example, 200°C to 300°C), and has suppressed dimensional changes and excellent heat resistance; and a power storage element including the same.

Means for Solving the Problems

[0006] 1. An embodiment of the present invention comprises a winding body formed by winding a plurality of thin-film electrodes, an adhesive tape for securing the winding body, and an electrolyte, wherein the adhesive tape comprises a base material and an adhesive layer disposed on at least one side of the base material, the base material comprises polyphenylene sulfide, and the adhesive layer comprises an acrylic polymer as a base polymer, an isocyanate crosslinking agent, and a tackifying resin, the acrylic polymer comprises constituent units derived from (meth)acrylate alkyl ester having a linear or branched alkyl group having 5 to 15 carbon atoms in the alkyl group, and the content ratio of the constituent units derived from (meth)acrylate alkyl ester having a linear or branched alkyl group having 5 to 15 carbon atoms in the alkyl group is 80 to 99 parts by weight per 100 parts by weight of the total amount of constituent units derived from (meth)acrylate alkyl ester having a linear or branched alkyl group having 5 to 15 carbon atoms in the alkyl group and constituent units derived from acrylic acid. 2. In the energy storage element described in item 1 above, the content ratio of the isocyanate-based crosslinking agent may be 0.1 to 3 parts by weight per 100 parts by weight of the acrylic polymer. 3. In the energy storage element described in 1 or 2 above, the content ratio of the tackifying resin may be 1 to 80 parts by weight per 100 parts by weight of the acrylic polymer. 4. The energy storage element described in any of items 1 to 3 above may further contain a crosslinking agent. 5. In the energy storage element described in any of items 1 to 4 above, the tackifying resin may be a phenolic tackifying resin or a rosin ester tackifying resin. 6. In the energy storage element described in item 4 above, the crosslinking aid may be a polyol. 7. In the energy storage element described in any of items 1 to 6 above, the adhesive layer may be configured without an epoxy crosslinking agent. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an energy storage element comprising an adhesive tape that can be used to secure the winding of an electrode member, which exhibits sufficient adhesive strength even at high temperatures (for example, 200°C to 300°C), and has excellent heat resistance with suppressed dimensional changes. In such an energy storage element, peeling of the adhesive tape (specifically, peeling of the ends) is prevented. Furthermore, the adhesive tape has excellent release properties from the back surface of the substrate, and the phenomenon of the adhesive layer remaining on the back surface of the substrate (adhesive removal phenomenon) can be prevented. As a result, it has excellent unwinding properties when wound in a roll shape, and the adhesive tape is prevented from interfering with the function of the energy storage element. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional view of an adhesive tape according to one embodiment of the present invention. [Modes for carrying out the invention]

[0009] An energy storage element according to an embodiment of the present invention includes a winding body formed by winding a plurality of thin-film electrodes, an adhesive tape for securing the winding body, and an electrolyte. The energy storage element may typically be a capacitor element such as an aluminum electrolytic capacitor.

[0010] A. Overview of adhesive tape Figure 1 is a schematic cross-sectional view of an adhesive tape according to one embodiment of the present invention. The adhesive tape 100 comprises a base material 10 and an adhesive layer 20 disposed on at least one side of the base material 10. In one embodiment, the adhesive tape of the present invention is a single-sided adhesive tape as shown in Figure 1. Although not shown, the adhesive tape of the present invention may be provided with a release liner on the outside of the adhesive layer for the purpose of protecting the adhesive surface until it is put into use.

[0011] The initial thickness of the above adhesive tape (the thickness immediately after manufacturing the adhesive tape, before the adhesive layer swells) is preferably 15 μm to 80 μm, and more preferably 30 μm to 60 μm. Within this range, the adhesive tape can be applied to small energy storage elements.

[0012] The adhesive strength of the above adhesive tape to a stainless steel plate at 23°C is preferably 2N / 20mm to 14N / 20mm, more preferably 3N / 20mm to 12N / 20mm, and even more preferably 4N / 20mm to 10N / 20mm. Within this range, an adhesive tape suitable for fixing electrode elements can be provided. In this specification, adhesive strength refers to the adhesive strength measured by a method in accordance with JIS Z 0237:2000, where the adhesive tape is attached to the adherend (SUS304BA) by one back-and-forth motion of a 2kg roller, left for 30 minutes at the measurement temperature, and then the adhesive tape is peeled off under conditions of a peeling angle of 180° and a peeling speed (tensile speed) of 300mm / min to measure the adhesive strength.

[0013] (Adhesive layer) The above adhesive layer is formed by a predetermined adhesive. The adhesive comprises an acrylic polymer as a base polymer, an isocyanate crosslinking agent, and a tackifying resin.

[0014] The above acrylic polymer contains structural units derived from alkyl acrylates (hereinafter also referred to as C5-15 acrylic monomers) having linear or branched alkyl groups with 5 to 15 carbon atoms in the alkyl group. In this specification, (meth)acrylic means acrylic and / or methacrylic. Preferably, the above acrylic polymer contains structural units derived from alkyl acrylates having linear or branched alkyl groups with 5 to 15 carbon atoms in the alkyl group. Examples of alkyl (meth)acrylate esters include pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, and pentadecyl (meth)acrylate. In the adhesive layer, the content of constituent units derived from alkyl (meth)acrylate having a linear or branched alkyl group with 5 to 15 carbon atoms in the alkyl group is preferably 70 to 99 parts by weight, more preferably 75 to 98 parts by weight, even more preferably 80 to 98 parts by weight, particularly preferably 82 to 98 parts by weight, and most preferably 85 to 95 parts by weight, per 100 parts by weight of the acrylic polymer. The number of carbon atoms in the alkyl group of the alkyl (meth)acrylate is more preferably 5 to 12, and even more preferably 6 to 10.

[0015] The above acrylic polymer further contains constituent units derived from acrylic acid. The content of the constituent units derived from acrylic acid is preferably 0.5 to 20 parts by weight, more preferably 1 to 20 parts by weight, even more preferably 2 to 18 parts by weight, particularly preferably 3 to 15 parts by weight, and most preferably 4 to 10 parts by weight, per 100 parts by weight of the acrylic polymer.

[0016] The content ratio of constituent units derived from C5-15 acrylic monomer is 80 to 99 parts by weight, more preferably 82 to 98 parts by weight, even more preferably 85 to 95 parts by weight, and particularly preferably 90 to 95 parts by weight, based on 100 parts by weight of the total amount of constituent units derived from C5-15 acrylic monomer and acrylic acid. Within this range, an adhesive tape exhibiting excellent tackiness at high temperatures and in an electrolyte can be obtained. Furthermore, the shrinkage of the substrate at high temperatures can be suppressed by the adhesive layer, providing an adhesive tape with excellent heat resistance from the viewpoint of dimensional stability. In addition, it exhibits excellent peelability from the back surface of the substrate, preventing the phenomenon of the adhesive layer remaining on the back surface of the substrate (adhesive removal phenomenon), and as a result, an adhesive tape with excellent unwinding properties when wound into a roll can be provided. According to the present invention, the adhesive removal phenomenon can be prevented with little influence from the type of substrate, and the above effects can be obtained even when using a PPS substrate with excellent heat resistance, for example. One of the major achievements of this invention is that it achieves both desirable adhesive strength in the electrolyte solution, heat resistance, and prevention of adhesive shedding.

[0017] The content ratio of acrylic acid-derived structural units is preferably 1 to 20 parts by weight, more preferably 2 to 18 parts by weight, even more preferably 3 to 15 parts by weight, and particularly preferably 4 to 10 parts by weight, based on 100 parts by weight of the total amount of structural units derived from C5-15 acrylic monomer and structural units derived from acrylic acid. Within this range, the above effects become significant. In particular, the hardness of the adhesive layer can be nicely adjusted, and an adhesive tape with excellent heat resistance can be obtained.

[0018] In addition to adjusting the Tg, the above-mentioned acrylic polymer may contain, if necessary, other monomer-derived structural units copolymerizable with the above-mentioned alkyl (meth)acrylate for the purpose of modifying properties such as cohesiveness, heat resistance, and crosslinkability. Other monomers such as carboxyl group-containing monomers like methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and carboxyethyl acrylate; acid anhydride group-containing monomers like maleic anhydride and eicotanoic anhydride; hydroxyl group-containing monomers as described below; amide monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, and N-methylolpropane(meth)acrylamide; vinyl ester monomers; styrene monomers; vinyl ether monomers; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing acrylic monomers such as glycidyl (meth)acrylate; olefin monomers; diene monomers; amino group-containing monomers such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate; (meth) Monomers containing alkoxy groups such as methoxyethyl acrylate, ethoxyethoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, and methoxypolyethylene glycol (meth)acrylate; monomers having nitrogen atom-containing rings such as N-vinylpyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, and N-vinylpiperidone; N-vinyl carboxylic acid amides; monomers containing sulfonic acid groups such as styrene sulfonic acid and allyl sulfonic acid; monomers containing phosphate groups such as 2-hydroxyethyl acryloyl phosphate; maleimide monomers; itacolinimide monomers; succinimide monomers such as N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, and N-(meth)acryloyl-8-oxyoctamethylenesuccinimide; glycol-based acrylic ester monomers; monomers having oxygen atom-containing heterocycles such as tetrahydrofurfuryl (meth)acrylate;Acrylic ester monomers containing fluorine atoms such as fluorine-based (meth)acrylates; acrylic ester monomers containing silicon atoms such as silicone-based (meth)acrylates; hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, polyfunctional epoxy acrylate, polyfunctional polyester acrylate, polyfunctional polyurethane acrylate, divinylbenzene, butyl di(meth)acrylate, hexyl di(meth)acrylate and other polyfunctional monomers, etc. These monomer components may be used alone or in combination of two or more kinds.;

[0019] The weight average molecular weight of the above acrylic polymer is preferably 800,000 or more, more preferably 900,000 or more, and still more preferably 1,000,000 or more. Within such a range, an adhesive layer having preferable swelling properties can be formed. The upper limit of the weight average molecular weight of the acrylic polymer is preferably 2,000,000, more preferably 1,500,000. The above weight average molecular weight is measured by GPC (gel permeation chromatography). The measurement conditions are as follows. The weight average molecular weight is calculated based on polystyrene conversion. Measuring device: HLC-8120GPC (product name, manufactured by Tosoh Corporation) Column: TSKgel GMH-H(S)×2 (product number, manufactured by Tosoh Corporation) Flow rate: 0.5 ml / min Injection volume: 100 μl Column temperature: 40 °C Eluent: THF Injected sample concentration: 0.1 wt% Detector: differential refractometer

[0020] The above adhesive contains an isocyanate-based crosslinking agent. Specific examples of the above isocyanate-based crosslinking agent include: lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate; aromatic isocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate; and trimethylolpropane / tolylene diisocyanate. Examples include isocyanate adducts such as socyanate trimer adducts (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L"), trimethylolpropane / hexamethylene diisocyanate trimer adducts (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HL"), and isocyanurate derivatives of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HX"); and Takenate D-101E (tolylene diisocyanate, TDI) manufactured by Mitsui Chemicals, Inc.

[0021] The content of the above-mentioned isocyanate-based crosslinking agent is preferably 0.1 to 3 parts by weight, more preferably 0.6 to 2 parts by weight, and even more preferably 1 to 2 parts by weight, per 100 parts by weight of the acrylic polymer. Within this range, an adhesive layer with appropriate hardness can be formed, and as a result, an adhesive tape with suppressed adhesive peeling can be obtained.

[0022] In one embodiment, the adhesive is configured without an epoxy crosslinking agent. In another embodiment, the content of the epoxy crosslinking agent is preferably 1 part by weight or less, more preferably 0.5 parts by weight or less, and even more preferably 0.1 parts by weight or less, per 100 parts by weight of the acrylic polymer. Within this range, an adhesive layer with appropriate hardness can be formed, and as a result, an adhesive tape with suppressed adhesive peeling can be obtained.

[0023] In one embodiment, the adhesive further comprises any suitable crosslinking aid. Examples of crosslinking aids include organometallic compounds, metal chelate compounds, compounds containing multiple hydroxyl groups, and amine compounds containing multiple hydroxyl groups. Preferably, a compound containing multiple hydroxyl groups (more preferably an amine compound containing multiple hydroxyl groups) is used as the crosslinking aid. Preferably, a compound having three or more functional groups is used. In one embodiment, a high molecular weight polyol is used. Using a high molecular weight polyol reduces the influence of variations in the degree of crosslinking due to the amount added. The amine compounds containing multiple hydroxyl groups are not particularly limited as long as they have at least two hydroxyl groups (alcoholic hydroxyl groups) in their molecule. For example, amine compounds containing multiple hydroxyl groups disclosed in Japanese Patent Application Publication No. 2009-079203, such as N,N,N′,N′-tetrakis(2-hydroxyethyl)ethylenediamine and N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine, as well as ethylenediamine polyols such as polyoxyethylene condensates of ethylenediamine, polyoxypropylene condensates of ethylenediamine, and polyoxyethylene-polyoxypropylene condensates of ethylenediamine, can be preferably used. In addition, commercially available amine compounds such as "EDP-300," "EDP-450," "EDP-1100," and "Pluronic®" (all manufactured by ADEKA Corporation) can also be used.

[0024] The crosslinking agent content is preferably 0.05 to 3 parts by weight, more preferably 0.1 to 2 parts by weight, and even more preferably 0.2 to 1 part by weight, per 100 parts by weight of the acrylic polymer. Within this range, an adhesive layer with appropriate hardness can be formed, and as a result, an adhesive tape with suppressed adhesive peeling can be obtained.

[0025] The above adhesive contains a tackifying resin. By including a tackifying resin, it is possible to obtain an adhesive tape that achieves both the maintenance of adhesiveness in an electrolyte solution, heat resistance, and prevention of adhesive peeling.

[0026] As the tackifying resin, any suitable tackifying resin can be used as long as it does not impair the effects of the present invention. Examples of such tackifying resins include phenolic tackifying resins, terpene tackifying resins, modified terpene tackifying resins, rosin tackifying resins (preferably rosin ester tackifying resins), hydrocarbon tackifying resins, epoxy tackifying resins, polyamide tackifying resins, elastomer tackifying resins, and ketone tackifying resins.

[0027] In one embodiment, a phenolic tackifying resin is used as the tackifying resin. Examples of phenolic tackifying resins include terpene phenol resins, hydrogenated terpene phenol resins, alkylphenol resins, and rosin phenol resins. Terpene phenol resins refer to polymers containing terpene residues and phenol residues, and are a concept that encompasses both copolymers of terpenes and phenol compounds (terpene-phenol copolymer resins) and homopolymers or copolymers of terpenes modified with phenol (phenol-modified terpene resins). Examples of terpenes that constitute such terpene phenol resins include monoterpenes such as α-pinene, β-pinene, and limonene (including d-isomers, l-isomers, and d / l-isomers (dipentene)). Hydrogenated terpene phenol resins refer to hydrogenated terpene phenol resins having a structure obtained by hydrogenating such terpene phenol resins, and are sometimes called hydrogenated terpene phenol resins. Alkylphenol resins are resins (oily phenol resins) obtained from alkylphenols and formaldehyde. Examples of alkylphenol resins include novolac type and resol type. Examples of rosinphenol resins include phenol-modified products of rosins or various rosin derivatives (including rosin esters, unsaturated fatty acid-modified rosins, and unsaturated fatty acid-modified rosin esters). Examples of rosinphenol resins include rosinphenol resins obtained by methods such as adding phenol to rosins or various rosin derivatives with an acid catalyst and then thermal polymerization.

[0028] Examples of terpene-based tackifying resins include polymers of terpenes (typically monoterpenes) such as α-pinene, β-pinene, d-limonene, l-limonene, and dipentene. Examples of single-molecule polymers of terpenes include α-pinene polymers, β-pinene polymers, and dipentene polymers.

[0029] Examples of modified terpene resins include styrene-modified terpene resins and hydrogenated terpene resins.

[0030] The concept of rosin-based tackifying resins encompasses both rosins and rosin derivative resins. Examples of rosins include unmodified rosins (raw rosins) such as gum rosin, wood rosin, and tall oil rosin; and modified rosins (hydrogenated rosin, disproportionated rosin, polymerized rosin, and other chemically modified rosins) obtained by hydrogenation, disproportionation, polymerization, etc.

[0031] Examples of rosin derivative resins include rosin esters such as unmodified rosin esters (esters of unmodified rosin and alcohols) and modified rosin esters (esters of modified rosin and alcohols); unsaturated fatty acid modified rosins obtained by modifying rosins with unsaturated fatty acids; unsaturated fatty acid modified rosin esters obtained by modifying rosin esters with unsaturated fatty acids; rosin alcohols obtained by reducing the carboxyl groups of rosins or rosin derivative resins (rosin esters, unsaturated fatty acid modified rosins, unsaturated fatty acid modified rosin esters, etc.); and metal salts thereof. Examples of rosin esters include methyl esters, triethylene glycol esters, glycerin esters, and pentaerythritol esters of unmodified rosin or modified rosin (e.g., hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.).

[0032] Examples of hydrocarbon-based tackifying resins include aliphatic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aliphatic-aromatic petroleum resins (such as styrene-olefin copolymers), aliphatic-alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone resins, and coumarone-indene resins.

[0033] The content ratio of the tackifying resin is preferably 1 to 80 parts by weight, more preferably 4 to 50 parts by weight, even more preferably 5 to 40 parts by weight, and particularly preferably 5 to 20 parts by weight, per 100 parts by weight of the acrylic polymer.

[0034] The above adhesive may contain any other suitable additives as needed. Examples of such additives include plasticizers (e.g., trimellitic acid ester plasticizers, pyromellitic acid ester plasticizers), pigments, dyes, fillers, antioxidants, conductive materials, ultraviolet absorbers, light stabilizers, release modifiers, softeners, surfactants, flame retardants, antioxidants, solvents, and the like.

[0035] The initial thickness (thickness before swelling) of the adhesive layer is preferably 1 μm to 50 μm, and more preferably 3 μm to 30 μm. In the embodiments of the present invention, heat resistance can be maintained even if the thickness of the adhesive layer is reduced. It is believed that reducing the thickness of the adhesive layer can suppress the adhesive peeling phenomenon.

[0036] The tensile modulus of the adhesive layer at 23°C is 0.001 MPa to 0.1 MPa, more preferably 0.003 MPa to 0.03 MPa, and even more preferably 0.005 MPa to 0.015 MPa. Within this range, an adhesive tape can be obtained that achieves both productivity during the production of energy storage elements (e.g., capacitor elements), heat resistance, and prevention of adhesive peeling. In this specification, the tensile modulus E is the value obtained by dividing the difference between the stress σ1 when the displacement ε1 is 2.5 mm and the stress σ2 when the displacement ε2 is 5.0 mm (σ2-σ1) by the difference in displacement (ε2-ε1), when a round bar-shaped adhesive layer with a diameter of 1.9 mm is measured, with both ends of the round bar-shaped adhesive layer gripped at a distance of 100 mm between grips and pulled at a speed of 300 mm / min. Formula: Tensile modulus E = (σ² - σ¹) / (ε² - ε¹) The tensile modulus can be measured, for example, using an Autograph instrument manufactured by Shimadzu Corporation (model: AGX-10kNV2D).

[0037] (base material) As the substrate, a resin film containing polyphenylene sulfide (PPS) is used. Preferably, the PPS content in the substrate is 90% to 100% by weight. Using polyphenylene sulfide (PPS) makes it possible to obtain an adhesive tape with excellent heat resistance. The substrate may have a multi-layer structure. For example, a substrate in which a back treatment layer, an undercoat layer, a secondary adhesive layer, etc., are formed on the resin film may be used.

[0038] The thickness of the above-mentioned substrate is preferably 10 μm to 50 μm, more preferably 12 μm to 40 μm, and even more preferably 13 μm to 30 μm.

[0039] The above adhesive tape can be manufactured by any suitable method. For example, an adhesive containing the acrylic polymer and optionally added additives can be applied to the substrate, and then dried to form the tape. Alternatively, an adhesive layer may be formed on another support, and then the adhesive layer may be transferred to the substrate.

[0040] B. Coiled body The above-mentioned winding can be a known configuration as a winding within an energy storage element (capacitor element). For example, the above-mentioned winding can be constructed by winding a plurality of thin-film electrodes (anodic foil and cathode foil) stacked with a separator in between.

[0041] C. Electrolyte The above-mentioned electrolyte can be a known configuration as an electrolyte in an energy storage element (capacitor element). [Examples]

[0042] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The evaluation methods in the examples are as follows. In the examples, unless otherwise specified, "parts" and "%" are based on weight.

[0043] [Example 1] In a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser, 95 parts by weight of 2-ethylhexyl acrylate (2EHA), 5 parts by weight of acrylic acid (AA), 0.3 parts by weight of initiator (manufactured by NOF Corporation, trade name "Niper BW"), and 120 parts by weight of ethyl acetate were charged. Nitrogen gas was introduced while gently stirring, and the polymerization reaction was carried out for approximately 6 hours while maintaining the liquid temperature in the flask at around 62°C to obtain an acrylic copolymer (1) with a weight-average molecular weight of 1.3 million. To 100 parts by weight of an acrylic copolymer (1), 2 parts by weight of an isocyanate crosslinking agent (manufactured by Mitsui Chemicals, trade name "Takenate D101E") and 17.5 parts by weight of a tackifying resin (polymerized rosin ester, manufactured by Harima Chemicals, trade name "Hariester KT-3") were added, and the mixture was diluted with toluene to prepare an adhesive with a solid content of 16%. The obtained adhesive was coated onto substrate A (a biaxially oriented polyphenylene sulfide film [product name "Torelina 3040" (thickness: 25 μm)] which had been back-treated with a long-chain alkyl back-treatment agent on one side of the substrate opposite to the adhesive coating surface, so that the thickness of the adhesive layer after drying was 28 μm, thereby obtaining an adhesive tape.

[0044] [Example 2] An acrylic copolymer (2) was obtained in the same manner as in Example 1, except that the amount of 2-ethylhexyl acrylate was 90 parts by weight and the amount of acrylic acid was 10 parts by weight. To 100 parts by weight of acrylic copolymer (2), 2 parts by weight of isocyanate crosslinking agent (manufactured by Mitsui Chemicals, trade name "Takenate D101E") and 17.5 parts by weight of tackifying resin (polymerized rosin ester, manufactured by Harima Chemicals, trade name "Hariestar KT-3") were added, and the mixture was diluted with toluene to prepare an adhesive with a solid content of 16%. The obtained adhesive was coated onto the substrate A so that the thickness of the adhesive layer after drying was 28 μm, thereby obtaining an adhesive tape.

[0045] [Example 3] Acrylic copolymer (2) was obtained in the same manner as in Example 2. To 100 parts by weight of acrylic copolymer (2), 1 part by weight of isocyanate crosslinking agent (manufactured by Mitsui Chemicals, trade name "Takenate D101E"), 0.5 parts by weight of ethylenediamine polyol (manufactured by ADEKA, trade name "ADEKA Polyether EDP-1100"), and 5 parts by weight of tackifying resin (terpene phenol tackifying agent, manufactured by Sumitomo Bakelite, trade name "Sumilite Resin PR-12603") were added, and the mixture was diluted with toluene to prepare an adhesive with a solid content of 16%. The obtained adhesive was coated onto the substrate A so that the thickness of the adhesive layer after drying was 28 μm, thereby obtaining an adhesive tape.

[0046] [Example 4] An acrylic copolymer (1) was obtained in the same manner as in Example 1. To 100 parts by weight of an acrylic copolymer (1), 1.8 parts by weight of an isocyanate crosslinking agent (manufactured by Mitsui Chemicals, trade name "Takenate D101E"), 0.3 parts by weight of an ethylenediamine polyol (manufactured by ADEKA, trade name "ADEKA Polyether EDP-1100"), and 4.9 parts by weight of a tackifying resin (terpene phenol resin, manufactured by Yasuhara Chemical Co., Ltd., trade name "YS Polystar S-145") were added, and the mixture was diluted with toluene to prepare an adhesive with a solid content of 16%. The obtained adhesive was coated onto the substrate A so that the thickness of the adhesive layer after drying was 28 μm, thereby obtaining an adhesive tape.

[0047] [Example 5] Acrylic copolymer (2) was obtained in the same manner as in Example 2. To 100 parts by weight of acrylic copolymer (2), 1.3 parts by weight of isocyanate crosslinking agent (manufactured by Mitsui Chemicals, trade name "Takenate D101E"), 0.25 parts by weight of ethylenediamine polyol (manufactured by ADEKA, trade name "ADEKA Polyester EDP-1100"), 0.4 parts by weight of tackifying resin (terpene phenol resin, manufactured by Yasuhara Chemical Co., Ltd., trade name "YS Polystar S-145"), and 15 parts by weight of tackifying resin (polymerized rosin ester, manufactured by Harima Chemicals, trade name "Hariestar KT-3") were added, and the mixture was diluted with toluene to prepare an adhesive with a solid content of 16%. The obtained adhesive was coated onto the substrate A so that the thickness of the adhesive layer after drying was 28 μm, thereby obtaining an adhesive tape.

[0048] [Example 6] Acrylic copolymer (2) was obtained in the same manner as in Example 2. To 100 parts by weight of acrylic copolymer (2), 1.2 parts by weight of isocyanate crosslinking agent (manufactured by Mitsui Chemicals, trade name "Takenate D101E"), 0.4 parts by weight of ethylenediamine polyol (manufactured by ADEKA, trade name "ADEKA Polyether EDP-1100"), and 5 parts by weight of tackifying resin (terpene phenol tackifying agent, manufactured by Sumitomo Bakelite, trade name "Sumilite Resin PR-12603") were added, and the mixture was diluted with toluene to prepare an adhesive with a solid content of 16%. The obtained adhesive was coated onto the substrate A so that the thickness of the adhesive layer after drying was 28 μm, thereby obtaining an adhesive tape.

[0049] [Example 7] Acrylic copolymer (2) was obtained in the same manner as in Example 2. To 100 parts by weight of acrylic copolymer (2), 1.5 parts by weight of isocyanate crosslinking agent (manufactured by Mitsui Chemicals, trade name "Takenate D101E"), 0.5 parts by weight of ethylenediamine polyol (manufactured by ADEKA, trade name "ADEKA Polyether EDP-1100"), and 5 parts by weight of tackifying resin (terpene phenol resin, manufactured by Yasuhara Chemical Co., Ltd., trade name "YS Polystar S-145") were added, and the mixture was diluted with toluene to prepare an adhesive with a solid content of 16%. The obtained adhesive was coated onto the substrate A so that the thickness of the adhesive layer after drying was 28 μm, thereby obtaining an adhesive tape.

[0050] [Example 8] Acrylic copolymer (2) was obtained in the same manner as in Example 2. To 100 parts by weight of acrylic copolymer (2), 1.5 parts by weight of isocyanate crosslinking agent (manufactured by Mitsui Chemicals, trade name "Takenate D101E"), 0.5 parts by weight of ethylenediamine polyol (manufactured by ADEKA, trade name "ADEKA Polyether EDP-1100"), and 5 parts by weight of tackifying resin (polymerized rosin ester, manufactured by Harima Chemicals, trade name "Hariester KT-3") were added, and the mixture was diluted with toluene to prepare an adhesive with a solid content of 16%. The obtained adhesive was coated onto the substrate A so that the thickness of the adhesive layer after drying was 28 μm, thereby obtaining an adhesive tape.

[0051] [Example 9] Acrylic copolymer (2) was obtained in the same manner as in Example 2. To 100 parts by weight of acrylic copolymer (2), 1.3 parts by weight of isocyanate crosslinking agent (manufactured by Mitsui Chemicals, trade name "Takenate D101E"), 0.25 parts by weight of ethylenediamine polyol (manufactured by ADEKA, trade name "ADEKA Polyether EDP-1100"), and 17.5 parts by weight of tackifying resin (polymerized rosin ester, manufactured by Harima Chemicals, trade name "Hariestar KT-3") were added, and the mixture was diluted with toluene to prepare an adhesive with a solid content of 16%. The obtained adhesive was coated onto the substrate A so that the thickness of the adhesive layer after drying was 28 μm, thereby obtaining an adhesive tape.

[0052] [Example 10] Acrylic copolymer (2) was obtained in the same manner as in Example 2. To 100 parts by weight of acrylic copolymer (2), 1.3 parts by weight of isocyanate crosslinking agent (manufactured by Mitsui Chemicals, trade name "Takenate D101E"), 0.25 parts by weight of ethylenediamine polyol (manufactured by ADEKA, trade name "ADEKA Polyether EDP-1100"), 5 parts by weight of tackifying resin (terpene phenol tackifying agent, manufactured by Sumitomo Bakelite, trade name "Sumilite Resin PR-12603"), and 12.5 parts by weight of tackifying resin (polymerized rosin ester, manufactured by Harima Chemicals, trade name "Hariester KT-3") were added, and the mixture was diluted with toluene to prepare an adhesive with a solid content of 16%. The obtained adhesive was coated onto the substrate A so that the thickness of the adhesive layer after drying was 28 μm, thereby obtaining an adhesive tape.

[0053] [Comparative Example 1] Acrylic copolymer (2) was obtained in the same manner as in Example 2. To 100 parts by weight of acrylic copolymer (2), 1.9 parts by weight of isocyanate crosslinking agent (manufactured by Mitsui Chemicals, trade name "Takenate D101E") and 0.05 parts by weight of epoxy crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, trade name "TETRAD-C") were added, and the mixture was diluted with toluene to prepare an adhesive with a solid content of 16%. The obtained adhesive was coated onto the substrate A so that the thickness of the adhesive layer after drying was 28 μm, thereby obtaining an adhesive tape.

[0054] [Comparative Example 2] An acrylic copolymer (1) was obtained in the same manner as in Example 1. To 100 parts by weight of an acrylic copolymer (1), 1.9 parts by weight of an isocyanate crosslinking agent (manufactured by Mitsui Chemicals, trade name "Takenate D101E") and 0.05 parts by weight of an epoxy crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, trade name "TETRAD-C") were added, and the mixture was diluted with toluene to prepare an adhesive with a solid content of 16%. The obtained adhesive was coated onto the substrate A so that the thickness of the adhesive layer after drying was 28 μm, thereby obtaining an adhesive tape.

[0055] [Comparative Example 3] Acrylic copolymer (2) was obtained in the same manner as in Example 2. To 100 parts by weight of acrylic copolymer (2), 1.9 parts by weight of isocyanate crosslinking agent (manufactured by Mitsui Chemicals, trade name "Takenate D101E") was added, and the mixture was diluted with toluene to prepare an adhesive with a solid content of 16%. The obtained adhesive was coated onto the substrate A so that the thickness of the adhesive layer after drying was 28 μm, thereby obtaining an adhesive tape.

[0056] [evaluation] The obtained adhesive tapes were subjected to the following evaluations. The results are shown in Table 1. (1) Detachment of the terminal A sample for evaluation was prepared by wrapping a 50mm length of adhesive tape (2mm wide) around a 3mm diameter aluminum rod in an atmosphere of 23℃. The sample was immersed in γ-butyllactone for 12 hours, and the length of the peeled-off end of the adhesive tape was confirmed. γ-butyllactone is a solvent commonly used as an electrolyte. (2) Heat resistance Three 3cm x 3cm adhesive tapes were pressed onto SUS304 in a 23°C environment to create evaluation samples. After reflowing the evaluation samples (maximum temperature: 260°C), the maximum shrinkage of the substrate relative to the adhesive layer on each of the four sides of the tape was measured. The average value from 12 measurement points was calculated, and the heat resistance was evaluated based on the calculated value. (3) glue removed Five samples, each cut to a width of 5 mm, were half-wrapped and bonded together. These were then subjected to heat-pressure bonding at 0.5 MPa for 3 minutes using a human press set to 60°C, 65°C, and 70°C. Afterward, the adhesive tape was peeled off at a 45° angle at a speed of 15 mm / min. The condition of the adhesive layer was visually inspected and evaluated according to the following criteria (lower scores indicate better results). 0 points: There is no adhesion of the adhesive layer, and no adhesive layer remains on the back of the substrate. 1 point: Although some tension is observed in the adhesive layer, no adhesive layer remains on the back of the substrate. 2 points: An adhesive layer remains on the back of the substrate.

[0057] [Table 1] [Explanation of symbols]

[0058] 10 Base material 20 Adhesive layer 100 Adhesive Tapes

Claims

1. The device comprises a winding body formed by winding multiple thin-film electrodes, an adhesive tape for securing the winding body, and an electrolyte solution. The adhesive tape comprises a base material and an adhesive layer disposed on at least one side of the base material. The substrate contains polyphenylene sulfide, The adhesive layer comprises an acrylic polymer as a base polymer, an isocyanate crosslinking agent, and a tackifying resin. The acrylic polymer contains constituent units derived from alkyl (meth)acrylate esters having linear or branched alkyl groups with 5 to 15 carbon atoms in the alkyl group, The content ratio of the constituent units derived from alkyl (meth)acrylate ester having a linear or branched alkyl group having 5 to 15 carbon atoms is 80 to 99 parts by weight per 100 parts by weight of the total amount of constituent units derived from alkyl (meth)acrylate ester having a linear or branched alkyl group having 5 to 15 carbon atoms and constituent units derived from acrylic acid. Energy storage element.

2. The energy storage element according to claim 1, wherein the content ratio of the isocyanate-based crosslinking agent is 0.1 to 3 parts by weight per 100 parts by weight of the acrylic polymer.

3. The energy storage element according to claim 1, wherein the content ratio of the tackifying resin is 1 to 80 parts by weight per 100 parts by weight of the acrylic polymer.

4. The energy storage element according to claim 1, further comprising a crosslinking agent.

5. The energy storage element according to claim 1, wherein the tackifying resin is a phenolic tackifying resin or a rosin ester tackifying resin.

6. The energy storage element according to claim 4, wherein the crosslinking aid is a polyol.

7. The energy storage element according to claim 1, wherein the adhesive layer is configured without an epoxy crosslinking agent.

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