Pressure sensitive adhesive composition for battery packaging material, pressure sensitive adhesive for battery packaging material, and battery packaging material

Abstract

To provide an adhesive composition for a battery packaging material excellent in adhesive force and rewinding property from the back surface of a base material which is not subjected to release treatment.SOLUTION: A pressure-sensitive adhesive composition for a battery packaging material contains an acrylic resin (A) and a crosslinking agent (B), wherein the acrylic resin (A) has a glass-transition temperature of - 30 °C. or higher, and the crosslinking agent (B) contains a metal-chelate-based crosslinking agent (b1).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition for battery packaging, an adhesive for battery packaging, and a battery packaging material. [Background technology]

[0002] Secondary batteries such as lithium-ion secondary batteries and nonaqueous electrolyte secondary batteries are used in portable devices as well as hybrid and electric vehicles, home storage batteries, etc. In particular, hybrid and electric vehicles, home storage batteries, etc. require high output, so they are often used in a configuration in which multiple battery cells are connected together. Such secondary batteries usually have a circuit board for voltage control, etc., and this circuit board and the secondary battery body are covered with metal, synthetic resin, etc. In particular, in order to efficiently connect these secondary batteries, it is necessary to consider the adhesiveness of the adhesive and film.

[0003] Generally, rectangular secondary batteries are widely used, and many battery cells are also rectangular. Due to the adhesiveness issues of the adhesives and films used to connect such rectangular battery cells, it is required to wind the battery cells from the back side of a substrate that is not subjected to release treatment or a substrate that has been treated for easy adhesion.

[0004] When using adhesive tape that has not been subjected to release treatment, the backside of the substrate, etc., which has been treated to facilitate adhesion, comes into contact with the adhesive surface, making it impossible to pull out (rewind) the tape from the adhesive tape. For this reason, a release substrate is attached to provide a roll of tape, but this raises issues regarding yield due to the process of peeling off the release substrate and environmental considerations due to disposal.

[0005] In addition, in the case of large-capacity secondary batteries used in automobiles, the amount of heat generated during charging and discharging is large, causing the battery cells to become heated. Normally, the battery cells are cooled using a heat sink, and the packaging material must adhere tightly to the battery cells with high adhesive strength to prevent thermal resistance.

[0006] As examples of films, adhesives, and adhesive tapes used in such battery and battery cell packaging applications, Patent Document 1, for example, describes a sheet that replaces polyvinyl chloride packaging material and is used to cover a secondary battery by removing the release paper from the adhesive tape and utilizing the heat shrinkage of polyester. Patent Document 2 describes a battery cell packaging material that has excellent adhesive properties that can suppress the generation and retention of an air gap between the battery cell and the packaging material at high temperatures, and that also has excellent reworkability for the battery cell. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Utility Model Registration No. 3200706 [Patent Document 2] Japanese Patent Publication No. 2023-160122 Summary of the Invention [Problem to be solved by the invention]

[0008] In recent years, due to issues of cost and environmental considerations regarding separator disposal, there has been a demand for rolls that do not require a peelable substrate, and due to issues with adhesion during cell joining, there is a demand for rolls that can be easily pulled out (rewound) from the back side without being subjected to release treatment.

[0009] However, the technology disclosed in the above-mentioned document 1 requires the disposal of release paper, which raises environmental concerns. Also, the technology disclosed in the above-mentioned document 2 does not use release paper, so it needs to be pulled out from the back side (substrate) that has not been subjected to release treatment, but it cannot be pulled out (rewound) with a light force. Therefore, in this context, the present invention aims to provide an adhesive for battery packaging materials that can achieve both the necessary adhesive strength to battery cells and peeling (rewinding) from the back surface of a substrate that has not been subjected to a release treatment. [Means for solving the problem]

[0010] However, in light of these circumstances, the present inventors have conducted extensive research and have found that, in an adhesive composition for battery packaging materials containing an acrylic resin (A) and a crosslinking agent (B), by using an acrylic resin having a glass transition temperature of a specific temperature or higher and a metal chelate crosslinking agent, it is possible to provide an adhesive for battery packaging materials that can achieve both the necessary adhesive strength to battery cells, etc. and peeling (rewinding) from the back surface of a substrate that has not been subjected to a release treatment, and have thereby completed the present invention.

[0011] That is, the gist of the present invention relates to the following [1] to [6]. [1] A pressure-sensitive adhesive composition for battery packaging, comprising an acrylic resin (A) and a crosslinking agent (B), The acrylic resin (A) has a glass transition temperature of −30° C. or higher, The adhesive composition for battery packaging, wherein the crosslinking agent (B) contains a metal chelate crosslinking agent (b1). [2] The pressure-sensitive adhesive composition for battery packaging according to [1], wherein the acrylic resin (A) has a weight-average molecular weight of 100,000 to 2,000,000. [3] The pressure-sensitive adhesive composition for battery packaging according to [1] or [2], wherein the content of the crosslinking agent (B) is 0.01 to 10 parts by mass per 100 parts by mass of the acrylic resin (A). [4] A pressure-sensitive adhesive for battery packaging, obtained by crosslinking the pressure-sensitive adhesive composition for battery packaging according to any one of [1] to [3]. [5] A pressure-sensitive adhesive for battery packaging materials, wherein the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive for battery packaging materials according to [4] has an actually measured glass transition temperature of 0°C or higher. [6] A battery packaging material having an adhesive layer made of the adhesive for battery packaging material according to [4] or [5]. [Effects of the Invention]

[0012] The adhesive composition for battery packaging of the present invention is useful as a packaging material for battery cells because it can achieve both the necessary adhesive strength to battery cells and peeling (unwinding) from the back surface of a substrate that has not been subjected to a release treatment. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described in detail below. In this specification, (meth)acrylic acid means acrylic acid or methacrylic acid, (meth)acrylic means acrylic or methacrylic, (meth)acryloyl means acryloyl or methacryloyl, and (meth)acrylate means acrylate or methacrylate, respectively. In this specification, when the expression "X to Y" (X and Y are any numbers) is used, unless otherwise specified, it means "X or more, Y or less," as well as "preferably larger than X" or "preferably smaller than Y." Furthermore, when it is expressed as "X or more" (X is any number) or "Y or less" (Y is any number), it also means that "it is preferably greater than X" or "it is preferably less than Y." In the present specification, in which multiple numerical ranges are described in stages, each upper limit and each lower limit may be the upper limit or lower limit of any combined numerical range. For example, when the content of a certain component is described as "5 to 20 mass%, 10 to 15 mass%, "it may constitute each of the numerical ranges "5 to 15 mass%, " "10 to 20 mass%, " "5 to 10 mass%, " and "15 to 20 mass%.

[0014] An adhesive composition for battery packaging materials according to one embodiment of the present invention (hereinafter, sometimes referred to as "the adhesive composition") contains an acrylic resin (A) and a crosslinking agent (B). First, the acrylic resin (A) contained as an essential component in the present pressure-sensitive adhesive composition will be described.

[0015] <Acrylic resin (A)> The acrylic resin (A) is obtained by polymerizing a copolymerization component (a) containing a (meth)acrylic acid ester as a main component, and the content of each monomer relative to the total copolymerization component (a) can be considered as the content of structural units derived from that monomer in the acrylic resin (A) which is a copolymer.

[0016] The copolymerization component (a) contains, for example, an alkyl (meth)acrylate (a1), an ethylenically unsaturated monomer containing a functional group (a2), and another ethylenically unsaturated monomer (a3) ​​(excluding a1 and a2).

[0017] (Alkyl (meth)acrylate (a1)) Examples of the alkyl (meth)acrylate (a1) include (meth)acrylic acid alkyl ester monomers having an alkyl group having 1 to 4 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, and tert-butyl (meth)acrylate; pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, and isopropyl (meth)acrylate. Examples of (meth)acrylic acid alkyl ester monomers having an alkyl group having 5 or more carbon atoms include sodecyl (meth)acrylate, isodecyl (meth)methacrylate, isomistyryl (meth)acrylate, isostearyl (meth)acrylate, isoundecyl (meth)acrylate, isododecyl (meth)acrylate, isotridecyl (meth)acrylate, isopentadecyl (meth)acrylate, isohexadecyl (meth)acrylate, isoheptadecyl (meth)acrylate, 2-dodecyl-hexadecanyl (meth)acrylate, 2-tetradecyl-octadecanyl (meth)acrylate, and 1-methylheptyl (meth)acrylate. Of these, n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are preferred, and 2-ethylhexyl (meth)acrylate is particularly preferred.

[0018] The content of the acrylic (meth)acrylate (a1) derived therefrom is 10 to 90 mass % relative to all structural units of the acrylic resin (A), preferably 15 to 80 mass %, more preferably 25 to 70 mass %, and even more preferably 35 to 60 mass %. When the content derived from the acrylic (meth)acrylate (a1) is within the above range, the adhesive strength and tackiness tend to be good.

[0019] (Functional Group-Containing Ethylenically Unsaturated Monomer (a2)) Examples of the ethylenically unsaturated monomer (a2) containing the functional group include (meth)acrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, (meth)acrylamide N-glycolic acid, cinnamic acid, Michael adducts of (meth)acrylic acid (e.g., (meth)acrylic acid dimer, (meth)acrylic acid trimer, (meth)acrylic acid tetramer), 2-(meth)acryloyloxyethyl dicarboxylic acid monoesters (e.g., 2-(meth)acryloyloxyethyl succinic acid monoester ... p) carboxyl group-containing unsaturated monomers (a2-1) such as acryloyloxyethyl phthalate monoester, 2-(meth)acryloyloxyethyl hexahydrophthalate monoester, etc.; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-chloro 2-hydroxypropyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-hydroxy 3-phenoxypropyl (meth)acrylate, diethylene glycol (meth)acrylate, polyethylene glycol Hydroxyl group-containing unsaturated monomers such as glycidyl (meth)acrylate and N-methylol (meth)acrylamide; glycidyl group-containing unsaturated monomers such as glycidyl (meth)acrylate and allyl glycidyl (meth)acrylate; isocyanate group-containing unsaturated monomers such as 2-(meth)acryloyloxyethyl isocyanate; (meth)acrylamide, N-(n-butoxyalkyl) (meth)acrylamide, (meth)acrylamido-3-methylbutylmethylamine, dimethylaminoalkyl (meth)acrylamide, dimethyl Examples of the unsaturated monomer include amide group-containing unsaturated monomers such as diethyl(meth)acrylamide and diethyl(meth)acrylamide; olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid, and methallylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, styrene sulfonic acid, and salts thereof; and amino group-containing unsaturated monomers such as dimethylaminoethyl (meth)acrylate and diethylaminoethyl (meth)acrylate. At least one selected from these is used. Among these, carboxyl group-containing unsaturated monomers, hydroxyl group-containing unsaturated monomers, glycidyl group-containing unsaturated monomers, isocyanate group-containing unsaturated monomers, and amide group-containing unsaturated monomers are preferably used, more preferably carboxyl group-containing unsaturated monomers and hydroxyl group-containing unsaturated monomers, even more preferably carboxyl group-containing unsaturated monomers, and particularly preferably acrylic acid.

[0020] The content of the ethylenically unsaturated monomer (a2) containing the functional group is preferably 0.1 to 10 mass%, particularly preferably 0.3 to 9 mass%, further preferably 0.5 to 7 mass%, and particularly preferably 1 to 6 mass%, based on the total structural units of the acrylic resin (A). When the content derived from the ethylenically unsaturated monomer (a2) containing the functional group is within the above range, the balance between holding power and adhesive power tends to be good. On the other hand, if the amount is too large, the pot life during coating tends to be shortened, and if the amount is too small, crosslinking does not proceed well and cohesion tends to be poor.

[0021] (Other copolymerizable ethylenically unsaturated monomers (a3)) Examples of the other copolymerizable ethylenically unsaturated monomers (a3) ​​include aromatic ring-containing monomers such as phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, ethoxylated o-phenyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, styrene, and α-methylstyrene; alicyclic structure-containing (meth)acrylic acid ester monomers such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate; 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-butoxydiethylene glycol (meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxytriethylene glycol (meth)acrylate, and ethoxydiethylene glycol (meth)acrylate. Ether chain-containing (meth)acrylic acid ester monomers such as methoxydipropylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, octoxypolyethylene glycol-polypropylene glycol-mono(meth)acrylate, lauroxypolyethylene glycol mono(meth)acrylate, and stearoxypolyethylene glycol mono(meth)acrylate; acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyl toluene, vinylpyridine, vinylpyrrolidone, itaconic acid dialkyl ester, fumaric acid dialkyl ester, allyl alcohol, acrylic chloride, methyl vinyl ketone, N-acrylamidomethyltrimethylammonium chloride, allyl trimethylammonium chloride, dimethylallyl vinyl ketone, (meth)acryloylmorpholine; vinyl acetate, vinyl propionate, vinyl versatate, and vinyl stearate can be used alone or in combination of two or more. Among these, vinyl acetate is preferred because it improves adhesive strength.

[0022] Furthermore, when the objective is to increase the molecular weight, polyfunctional monomers such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, and divinylbenzene can also be used in combination.

[0023] The content of the other copolymerizable ethylenically unsaturated monomer (a3) ​​is preferably 80% by mass or more, more preferably 0.1 to 70% by mass, and even more preferably 0.2 to 60% by mass, based on the total polymerizable components. If the content derived from the other copolymerizable ethylenically unsaturated monomer (a3) ​​is too high, the copolymerizability of the polymer tends to decrease, and the polymer tends to remain as a residual monomer and generate an odor.

[0024] The acrylic resin (A) can be produced by polymerizing an alkyl (meth)acrylate (a1) with an appropriately selected copolymerization component containing a functional group-containing ethylenically unsaturated monomer (a2) and other copolymerizable ethylenically unsaturated monomers (a3). The polymerization can be carried out by a conventionally known method such as solution radical polymerization, suspension polymerization, bulk polymerization, or emulsion polymerization. Of these polymerization methods, solution radical polymerization and bulk polymerization are preferred, and solution radical polymerization is more preferred.

[0025] In the case of solution radical polymerization, for example, polymerization components containing the alkyl (meth)acrylate (a1) and a polymerization initiator are mixed or dropped into an organic solvent, and polymerization is carried out under predetermined polymerization conditions.

[0026] Examples of organic solvents used in solution radical polymerization reactions include aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane, esters such as ethyl acetate and butyl acetate, aliphatic alcohols such as n-propyl alcohol and isopropyl alcohol, and ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Among these solvents, ethyl acetate, acetone, methyl ethyl ketone, butyl acetate, toluene, and methyl isobutyl ketone are preferred from the standpoint of ease of polymerization reaction, chain transfer effect, ease of drying when applying the adhesive, and safety, and ethyl acetate, acetone, and methyl ethyl ketone are more preferred.

[0027] Examples of polymerization initiators used in such solution radical polymerization include azo initiators such as 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 4,4'-azobis(4-cyanovaleric acid), and 2,2'-azobis(methylpropionic acid), which are common radical polymerization initiators, and organic peroxides such as benzoyl peroxide, lauryl peroxide, di-t-butyl peroxide, and cumene hydroperoxide, and can be appropriately selected and used depending on the monomer used. These polymerization initiators can be used alone or in combination of two or more.

[0028] The acid value of the acrylic resin (A) is preferably 78 mgKOH / g or less, particularly preferably 63 mgKOH / g or less, even more preferably 55 mgKOH / g or less, and especially preferably 47 mgKOH / g or less. The lower limit is 0.5 mgKOH / g. If the acid value of the acrylic resin (A) is too high, the pot life when a crosslinking agent is added tends to be shortened, and if it is too low, the adhesive strength and cohesive strength tend to decrease. The acid value in this specification is determined by neutralization titration using potassium hydroxide or potentiometry.

[0029] The weight average molecular weight of the acrylic resin (A) is preferably from 100,000 to 2,000,000, particularly preferably from 200,000 to 1,500,000, further preferably from 250,000 to 1,000,000, and particularly preferably from 300,000 to 500,000. If the weight average molecular weight is too small, the cohesive strength will tend to decrease and the peelability will tend to decrease, whereas if the weight average molecular weight is too large, the adhesive strength will tend to decrease and production will tend to become difficult.

[0030] The dispersity (weight average molecular weight / number average molecular weight) of the acrylic resin (A) is preferably 2.5-8, particularly preferably 3.0-7.5, and further preferably 3.5-7. If the degree of dispersion is too high, the amount of low molecular weight components increases and the releasability tends to decrease, whereas if the degree of dispersion is too low, the adhesive strength tends to decrease and production tends to become difficult.

[0031] The weight-average molecular weights mentioned above are those calculated in terms of standard polystyrene molecular weights. The high-performance liquid chromatograph (Waters Japan, "Waters 2695 (main unit)" and "Waters 2414 (detector)") was equipped with a Shodex GPC KF-806L column (exclusion limit molecular weight: 2 × 10 7 Separation range: 100 to 2 × 10 7 The measurement is performed using three columns in series (theoretical plate number: 10,000 columns / column, filler material: styrene-divinylbenzene copolymer, filler particle size: 10 μm), and the number average molecular weight can also be measured in a similar manner. The dispersity can also be calculated from the weight average molecular weight and the number average molecular weight.

[0032] The calculated glass transition temperature (Tg) of the acrylic resin (A) is -30°C or higher, preferably -30 to 0°C, more preferably -28 to -10°C, and particularly preferably -26 to -20°C. If the calculated glass transition temperature is too high, the adhesive strength tends to decrease, whereas if it is too low, the acrylic resin tends to become too hard and the releasability tends to decrease.

[0033] The calculated glass transition temperature is calculated by the following Fox formula. In this specification, the unit of Tg is "°C." Specifically, in the case of a polymer (homopolymer) consisting of only a single monomer, a standard analytical value described in, for example, "Polymer Data Handbook" compiled by the Society of Polymer Science can be adopted, and in the case of a copolymer obtained by polymerizing n types of monomers, the calculated glass transition temperature can be considered to be calculated from the Tg of the homopolymer of each monomer.

[0034] 1 / Tg=w1 / Tg1+w2 / Tg2+·············Wk / Tgk where Tg is the glass transition temperature of the acrylic resin (A), Tg1, Tg2...Tgk are the Tg of the acrylic resin (A) alone of each monomer component, and w1, w2,...wk represent the molar fraction of each monomer component, with w1 + w2 +...wk=1.

[0035] The viscosity (25°C) of the acrylic resin (A) is preferably 50 to 10,000 mPa·s, more preferably 100 to 9,000 mPa·s, and particularly preferably 200 to 8,000 mPa·s. If the viscosity is too low, the cohesive force tends to decrease, and if it is too high, the coatability tends to decrease. The viscosity of the acrylic resin (A) is a value measured in accordance with JIS K5400 (1990) 4.5.3 rotational viscometer method.

[0036] The heating residue of the acrylic resin (A) is preferably 1 to 80% by mass, more preferably 5 to 70% by mass, and even more preferably 10 to 60% by mass. If the heating residue of the acrylic resin (A) is too low, unevenness in the coating thickness and repellency on the substrate tend to occur, whereas if it is too high, coating streaks tend to require dilution. The heating residue of the acrylic resin (A) is calculated by placing 1-2 g of the acrylic resin (A) solution on aluminum foil, heating and drying it for 60 minutes in a kettle (infrared dryer, 185 W, height 5 cm), and then calculating the amount remaining after drying. Heating residue (%) = amount remaining after heating (g) / acrylic resin (A) solution before heating (g) x 100.

[0037] <Crosslinking agent (B)> Next, the crosslinking agent (B) will be described. The crosslinking agent (B) contains a metal chelate-based crosslinking agent (b1), and may also contain a crosslinking agent that forms a chemical crosslink, such as an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an aziridine-based crosslinking agent, a melamine-based crosslinking agent, an aldehyde-based crosslinking agent, or an amine-based crosslinking agent, or a crosslinking agent that forms a physical crosslink, such as a polyfunctional acrylate-based crosslinking agent. By including the metal chelate crosslinking agent (b1), the reaction with the acrylic resin (A) proceeds more quickly, improving adhesive strength. Furthermore, by using the metal chelate crosslinking agent (b1) with an acrylic resin (A) having a high Tg, it tends to be possible to achieve both good rewindability and good adhesion.

[0038] Examples of the metal chelate crosslinking agent (b1) include acetylacetone and acetoacetyl ester coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. Among these, aluminum acetylacetonate is preferred.

[0039] Examples of the isocyanate crosslinking agent include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, hexamethylene diisocyanate, diphenylmethane-4,4-diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, tetramethylxylylene diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, adducts of these polyisocyanate compounds with polyol compounds such as trimethylolpropane, and biuret and isocyanurate forms of these polyisocyanate compounds.

[0040] Examples of the epoxy crosslinking agent include bisphenol A-epichlorohydrin epoxy resins, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, diglycerol polyglycidyl ether, 1,3'-bis(N,N-diglycidylaminomethyl)cyclohexane, and N,N,N',N'-tetraglycidyl-m-xylylenediamine.

[0041] Examples of the aziridine crosslinking agent include tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), and N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide). However, since such aziridine crosslinking agents have a short pot life and are mutagenic, their use may not be preferable depending on the intended use of the pressure-sensitive adhesive.

[0042] Examples of the melamine-based crosslinking agent include hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexaptoxymethylmelamine, hexapentyloxymethylmelamine, hexahexyloxymethylmelamine, and melamine resins.

[0043] Examples of the aldehyde crosslinking agent include glyoxal, malondialdehyde, succindialdehyde, maleic dialdehyde, glutaric dialdehyde, formaldehyde, acetaldehyde, and benzaldehyde.

[0044] Examples of the amine-based crosslinking agent include hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetraamine, diethylenetriamine, triethyltetraamine, isophoronediamine, amino resins, and polyamides.

[0045] These crosslinking agents may be used alone or in combination of two or more, but the metal chelate crosslinking agent (b1) is essential, and its content in the crosslinking agent (B) is preferably 50% by mass or more, 70% by mass or more, or 90% by mass or more, with the upper limit being 100% by mass.

[0046] The content of the crosslinking agent (B) is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 8 parts by mass, and particularly preferably 0.1 to 6 parts by mass, relative to 100 parts by mass of the acrylic resin (A). If the amount of crosslinking agent (B) is too small, the cohesive strength tends to decrease and sufficient durability tends to be insufficient, while if the amount is too large, the flexibility and adhesive strength tend to decrease, making peeling more likely to occur.

[0047] The content of the metal chelate crosslinking agent (b1) is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 4.5 parts by mass, and particularly preferably 0.1 to 4 parts by mass, relative to 100 parts by mass of the acrylic resin (A). If the amount of the metal chelate crosslinking agent (b1) is too small, the cohesive strength tends to decrease and sufficient durability tends to be insufficient, while if the amount is too large, the flexibility and adhesive strength tend to decrease, making peeling more likely to occur.

[0048] Generally, increasing the content of crosslinking agent in a pressure-sensitive adhesive composition increases the gel fraction of the pressure-sensitive adhesive layer, resulting in a decrease in adhesive strength on the surface side of the pressure-sensitive adhesive layer. Although peeling becomes easier, there is a tendency for adhesive strength to decrease. For this reason, it has traditionally been difficult to achieve conflicting adhesive properties such as adhesive strength and releasability from a substrate that has not been subjected to a release treatment. Therefore, in the present invention, by setting the glass transition temperature of the acrylic resin (A) to a specific temperature or higher and using a specific crosslinking agent, it is possible to achieve adhesive properties that allow both adhesive strength and peeling (rewinding) from the back surface of a substrate that has not been subjected to a release treatment.

[0049] <Other additives> Furthermore, the present pressure-sensitive adhesive composition may contain various additives, such as antistatic agents, other acrylic pressure-sensitive adhesives, other pressure-sensitive adhesives, tackifiers such as terpene resins, urethane resins, rosin, rosin esters, hydrogenated rosin esters, phenolic resins, aliphatic petroleum resins, alicyclic petroleum resins, and styrene resins, colorants, fillers, antioxidants, UV absorbers, deterioration inhibitors, and functional dyes, as well as compounds that develop or change color upon exposure to UV or radiation, provided that the effects of the present invention are not impaired. In addition to the above additives, the pressure-sensitive adhesive composition may also contain small amounts of impurities contained in the raw materials used to manufacture the components of the pressure-sensitive adhesive composition. The amounts of these additives added may be appropriately determined to achieve the desired physical properties, but are typically 50 parts by mass or less, 30 parts by mass or less, or 5 parts by mass or less per 100 parts by mass of the acrylic resin (A). Among these, it is preferable to add antioxidants, deterioration inhibitors, and antistatic agents in order to improve the stability of the resin over time.

[0050] <Adhesive composition> The pressure-sensitive adhesive composition of the present invention contains an acrylic resin (A) and a crosslinking agent (B). The content of the acrylic resin (A) in the entire pressure-sensitive adhesive composition is preferably 50% by mass or more, 70% by mass or more, or 90% by mass or more, with the upper limit being 98% by mass.

[0051] <Adhesive>

[0052] The present adhesive composition is used particularly as an organic solvent-containing adhesive composition, and becomes an adhesive by crosslinking (curing) it with heat in the presence of a crosslinking agent (B), and exhibits medium to high adhesive strength (approximately 3 N / 25 mm or more). The above-mentioned adhesive has excellent adhesive strength and rewindability from the back surface of a substrate that has not been subjected to a release treatment, and is therefore suitable for use as a packaging material for batteries and battery cells.

[0053] When used as a packaging material for the above-mentioned batteries and battery cells, an adhesive tape having an adhesive layer made of the present adhesive composition is usually used.

[0054] The pressure-sensitive adhesive has a measured glass transition temperature (Tg) of 0°C or higher, preferably 0 to 20°C, more preferably 0 to 15°C, even more preferably 0 to 10°C, and particularly preferably 0 to 5°C. In this embodiment, by setting the measured glass transition temperature (Tg) of the adhesive within the above range, it is possible to achieve both the adhesive strength required for the adhesive to the battery cell and peeling (unwinding) from the back surface of the substrate that has not been subjected to a release treatment. The reason for this is that the elastic modulus during unwinding at high speeds is in the glass region (Tg), and the elastic modulus during peeling at room temperature is close to the rubber region (Tg). The measured glass transition temperature (Tg) of the pressure-sensitive adhesive is a tan δ value measured using a viscoelasticity measuring device "DVA225" manufactured by IT Measurement Control Co., Ltd. The measurement temperature range was -80 to 80°C, the frequency was 1 Hz, and the temperature rise rate was 5°C / min.

[0055] <Adhesive tape> An adhesive tape having an adhesive layer made of the present adhesive composition may be in either a continuous or roll form, but is preferably in roll form because the present adhesive composition has excellent adhesive strength and ease of unwinding from the back surface of a substrate that has not been subjected to a release treatment. The above-mentioned adhesive tape can be produced, for example, as follows. In the present invention, the term "adhesive tape" also includes those expressed as "adhesive sheet" and "adhesive film."

[0056] First, the pressure-sensitive adhesive composition is applied to one or both sides of a support substrate to a predetermined thickness, and then heated and dried to form a pressure-sensitive adhesive layer. Next, a release sheet is attached to the surface of the pressure-sensitive adhesive layer, if necessary, to produce a pressure-sensitive adhesive tape. The resulting pressure-sensitive adhesive tape is then subjected to an aging treatment, if necessary, and then, when in use, the release sheet is peeled off from the pressure-sensitive adhesive layer for use. In this way, a pressure-sensitive adhesive layer is formed on one or both sides of the support substrate, and a release sheet is further provided on the surface of the pressure-sensitive adhesive layer, if necessary, to obtain a pressure-sensitive adhesive tape. Note that a release sheet is not usually required in the present invention.

[0057] Examples of the support substrate include metal foils such as aluminum, copper, and iron; polyester resins such as polyethylene naphthate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate / isophthalate copolymer; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; polyethylene fluoride resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyethylene fluoride; polyamides such as nylon 6 and nylon 6,6; vinyl polymers such as polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, and vinylon; cellulose resins such as cellulose triacetate and cellophane; acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate; synthetic resin films or sheets such as polystyrene, polycarbonate, polyarylate, and polyimide; paper such as fine paper and glassine paper; glass fiber; natural fiber; and single-layer or multi-layer bodies selected from synthetic fibers. The thickness of such a supporting substrate is usually 1 to 500 μm, and preferably 5 to 300 μm.

[0058] Furthermore, the release sheet may be, for example, any of the various synthetic resin sheets, paper, cloth, nonwoven fabric, etc. exemplified above as the supporting substrate, which have been subjected to a release treatment. Alternatively, a substrate-less adhesive tape can be produced by applying the above-mentioned adhesive composition to a release sheet, heating and drying the composition to form an adhesive layer, and then laminating a release sheet to the adhesive layer.

[0059] When applying the pressure-sensitive adhesive composition, it is preferable to dilute the pressure-sensitive adhesive composition in a solvent and then apply the diluted composition. The dilution concentration is preferably 5 to 80% by mass, and particularly preferably 10 to 70% by mass. The solvent may be any solvent that dissolves the pressure-sensitive adhesive composition, and examples of such solvents include ester-based solvents such as methyl acetate, ethyl acetate, methyl acetoacetate, and ethyl acetoacetate, ketone-based solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, aromatic solvents such as toluene and xylene, and alcohol-based solvents such as methanol, ethanol, and propyl alcohol. Among these, ethyl acetate, acetone, and toluene are preferably used in terms of solubility, drying properties, cost, etc.

[0060] The method for applying the pressure-sensitive adhesive composition is not particularly limited as long as it is a common application method, and examples thereof include roll coating, die coating, gravure coating, comma coating, and screen printing.

[0061] The heating and drying conditions may be any conditions that allow the pressure-sensitive adhesive composition to be dried, and examples include conditions such as 50 to 150°C, preferably 60 to 130°C, for about 1 to 10 minutes, preferably 1.5 to 5 minutes.

[0062] The aging treatment is carried out to balance the adhesive properties, and the aging conditions are a temperature typically between room temperature (20°C±20°C) and 70°C, and a time typically between 1 and 30 days. Specifically, the aging treatment may be carried out under conditions such as 20°C for 1 to 20 days, or 40°C for 1 to 7 days.

[0063] Furthermore, the thickness of the adhesive layer in the obtained adhesive tape is usually preferably 5 to 100 μm, more preferably 10 to 60 μm, and particularly preferably 15 to 50 μm. If the thickness of this adhesive layer is too thin, the adhesive properties tend to be difficult to stabilize, while if it is too thick, drying becomes difficult and the amount of outgassing tends to increase.

[0064] The thickness of the adhesive tape thus obtained is set appropriately depending on the application, but is preferably set in the range of 5 to 100 μm, for example.

[0065] The gel fraction of the pressure-sensitive adhesive layer is usually 20 to 99%, preferably 30 to 99%, and particularly preferably 40 to 95%. If the gel fraction is too low, cohesive failure will occur during peeling, and adhesive residue will tend to be left behind, whereas if the gel fraction is too high, the adhesive strength will tend to decrease and the tackiness will tend to decrease.

[0066] The adhesive tape having the adhesive layer may be adhered to the adherend without peeling off, and has an adhesive strength of usually 0.05 to 30 N / 25 mm, preferably 0.2 to 25 N / 25 mm, and particularly preferably 0.3 to 20 N / 25 mm. If the adhesive strength is too low, the adhesive may lift or peel off from the adherend, whereas if the adhesive strength is too high, the adhesive may not be repositionable or may undergo cohesive failure, resulting in adhesive residue. The adhesive strength can be measured by the method described in the examples below.

[0067] The pressure-sensitive adhesive tape having the pressure-sensitive adhesive layer can be unwound from a substrate that has not been subjected to a release treatment. The unwinding force is usually preferably such that the tape can be peeled off. If the tape can be peeled off, the unwinding force is preferably 0.05 to 10 N / 25 mm, and particularly preferably 0.1 to 5 N / 25 mm. If the unwinding force is too low, the tape may lift, and if it is too high, it may be difficult to pull out and use the tape. The unwinding force can be measured by the method described in the examples below.

[0068] When using the pressure-sensitive adhesive tape of the present invention, examples of the type of adherend include articles having various metal surfaces; polyester-based resins such as polyethylene naphthate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate / isophthalate copolymer; polyolefin-based resins such as polyethylene, polypropylene, and polymethylpentene; polyethylene fluoride resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyethylene fluoride; polyamides such as nylon 6 and nylon 6,6; vinyl polymers such as polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, and vinylon; cellulose-based resins such as cellulose triacetate and cellophane; acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate; and synthetic resin films, sheets, or plates such as polystyrene, polycarbonate, polyarylate, and polyimide.

[0069] <Battery packaging material> An adhesive tape having an adhesive layer made of the present adhesive composition is suitably used as a battery packaging material for covering at least a portion of the outer surface of a battery cell, battery, etc. Examples of the battery cell include battery cells used in non-aqueous electrolyte secondary batteries or solid electrolyte secondary batteries. Examples of the battery include paper-type ion batteries, button-type batteries, coin-type batteries, laminated-type batteries, cylindrical ion batteries, and prismatic batteries. The battery cells and batteries are used in hybrid vehicles, electric vehicles, home storage batteries, portable devices, etc. [Example]

[0070] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. In the examples, "parts" and "%" are by mass.

[0071] First, various acrylic resins were prepared as follows: The weight average molecular weight, dispersity, glass transition temperature, and acid value of the acrylic resins, and the measured glass transition temperature of the pressure-sensitive adhesive layer were measured according to the methods described above. The viscosity was measured in accordance with JIS K5400 (1990) 4.5.3 Rotational Viscosity Method. The heating residue was measured by placing 1 to 2 g of resin solution on aluminum foil, heating and drying it for 60 minutes in a kettle (infrared dryer, 185 W, height 5 cm), and calculating the amount remaining after drying. The heating residue (%) was measured as follows: amount remaining after heating (g) / resin solution before heating (g) × 100.

[0072] [Manufacturing Example 1] [Production of acrylic resin (A-1)] A 4L round-bottom, four-neck flask was charged with 689g of ethyl acetate and 129.5g of toluene, and the mixture was stirred. The water bath temperature was set to 98°C, and 1.15g of initiator AIBN was added when the internal temperature reached 60°C. After refluxing began, a monomer mixture consisting of 485.0g of 2-ethylhexyl acrylate (a1) (45.1% of the total copolymerization component (a)), 562g of vinyl acetate (a3) ​​(52.2% of the total copolymerization component (a)), and 29g of acrylic acid (a2-1) (2.7% of the total copolymerization component (a)) was added dropwise over a two-hour period. Three hours after the start of the dropwise addition, 1.05g of additional initiator AIBN and 79.5g of dissolving solvent toluene were added. Five hours after the start of the dropwise addition, 0.7g of additional initiator AIBN and 14g of dissolving solvent toluene were added. Seven hours after the start of the dropwise addition, 0.35 g of AIBN was added as an additional initiator and 15 g of toluene as a dissolution solvent. Nine hours after the start of the reaction, 375 g of toluene as a dilution solvent was added, and the mixture was then cooled to terminate the reaction. After the reaction, 3.25 g of sesquioctyl phosphate triethanolamine salt and 50 g of toluene as a dilution solvent were stirred and dissolved to obtain acrylic resin (A-1). The physical properties of the resulting acrylic resin (A-1) are shown in Table 1 below. The reaction was carried out while maintaining the internal temperature at 78 to 95°C from the start to the end of the reaction.

[0073] [Manufacturing Example 2] [Production of acrylic resin (A-2)] A 4L round-bottom, four-neck flask was charged with 541.75g ​​of ethyl acetate and 45.75g of toluene, and the mixture was stirred. The water bath temperature was set to 98°C, and 0.5g of initiator AIBN was added when the internal temperature reached 60°C. After refluxing began, a monomer mixture consisting of 739.50g of n-butyl acrylate (a1) (88.75% of the total copolymerization component (a)), 41.75g ​​of vinyl acetate (a3) ​​(5% of the total copolymerization component (a)), 50.0g of acrylic acid (a2-1) (6% of the total copolymerization component (a)), and 1.675g of 2-hydroxymethacrylate (a2) (0.20% of the total copolymerization component (a)) was added dropwise over 2 hours. Three hours after the start of the dropwise addition, 0.425 g (0.05% based on the total copolymerization component (a)) of 2-hydroxymethacrylate (a2) was added as an additional monomer and 80.5 g of toluene as a dissolving solvent. 3.5 hours after the start of the dropwise addition, 0.6 g of AIBN was added as an additional initiator and 18.5 g of toluene as a dissolving solvent. 6.5 hours after the start of the reaction, 720 g of toluene as a dilution solvent was added, and the mixture was then cooled to terminate the reaction, yielding acrylic resin (A-2). The physical properties of the resulting acrylic resin (A-2) are shown in Table 1 below. The reaction was carried out while maintaining the internal temperature at 78 to 95°C from the start to the end of the reaction.

[0074] [Manufacturing Example 3] [Production of acrylic resin (A-3)] A 2L round-bottom, four-neck flask was charged with 250g of ethyl acetate and stirred. The water bath temperature was set to 95°C. When the internal temperature reached 60°C, 0.460g of initiator AIBN was added. After refluxing began, a monomer mixture consisting of 255.0g of 2-ethylhexyl acrylate (a1) (51% of the total copolymerization component (a)), 200.0g of n-butyl acrylate (a1) (40% of the total copolymerization component (a)), 25.0g of vinyl acetate (a3) ​​(5% of the total copolymerization component (a)), 19.5g of acrylic acid (a2-1) (3.9% of the total copolymerization component (a)), and 0.5g of 2-hydroxyethyl methacrylate (a2) (0.1% of the total copolymerization component (a)) was added dropwise over two hours. Three hours after the start of the dropwise addition, 0.340g of additional initiator AIBN and 50g of ethyl acetate as a dissolution solvent were added. Furthermore, 5 hours after the start of the dropwise addition, 0.300 g of AIBN as an additional initiator and 25 g of ethyl acetate as a dissolving solvent were added. Further, 7 hours after the start of the dropwise addition, 0.150 g of AIBN as an additional initiator and 25 g of ethyl acetate as a dissolving solvent were added. Nine hours after the start of the reaction, 150 g of isopropyl alcohol as a dilution solvent was added, and then the mixture was cooled to terminate the reaction, thereby obtaining acrylic resin (A-3). The physical properties of the resulting acrylic resin (A-3) are shown in Table 1 below. The reaction was carried out while maintaining the internal temperature at 78 to 88°C from the start to the end of the reaction.

[0075] [Table 1]

[0076] The following crosslinking agent (B) was prepared: (b1-1): Aluminum acetylacetonate (manufactured by Mitsubishi Chemical Corporation; trade name "Coponyl 5792") (b'-1): Multifunctional epoxy resin 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Company, Inc.; product name "TETRAD-C") (b'-2): Trimethylolpropane / tolylene diisocyanate adduct (Mitsui Chemicals, Inc.; product name "Takenate D101E")

[0077] Example 1 2.4 parts of crosslinking agent (B-1) was blended with 100 parts (solid content equivalent) of the acrylic resin (A-1), and then diluted with ethyl acetate to a viscosity suitable for coating to obtain a pressure-sensitive adhesive composition.

[0078] <Examples 2 and 3, Comparative Examples 1 to 3> A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1, except that the blending amounts of each component were as shown in Table 2.

[0079] [Table 2]

[0080] [Preparation of adhesive tape] The pressure-sensitive adhesive compositions prepared in Example 1 and Comparative Examples 1, 2, and 3 were applied to untreated PET (38 μm film thickness; Toray Industries, Inc., trade name "Lumirror 38T60") using an applicator to a dried film thickness of 10 μm to 20 μm, and then dried at 100°C for 3 minutes. The pressure-sensitive adhesive layer was then bonded to a release film (polyethylene terephthalate film) (Mitsui Chemicals ICT Materials, Inc., trade name "SP-PET38-01") and an easy-adhesion film (50 μm film thickness; Toyobo Co., Ltd., trade name "Cosmoshine A4300"), respectively, and then aged at 40°C for 4 days to obtain two types of pressure-sensitive adhesive tapes: one with a release film backing and the other with an easy-adhesion film backing.

[0081] In Examples 2 and 3 above, adhesive tapes were obtained in the same manner as in Example 1 above, except that an easy-adhesion film (50 μm thick, manufactured by Toyobo Co., Ltd.: product name "Cosmoshine A4300") was replaced with an easy-adhesion film (50 μm thick, manufactured by Mitsubishi Chemical Corporation: product name "Diafoil O100E50[SE43-]") and an easy-adhesion film (50 μm thick, manufactured by Mitsubishi Chemical Corporation: product name "Diafoil O100J50[SJ30-]").

[0082] The two types of adhesive tapes obtained above, one with a release film back and one with an easy-adhesion film back, were evaluated as follows. The results are shown in Table 2 above.

[0083] <Rewindability> The above-mentioned adhesive back film was cut into a width of 25 mm and a length of 120 mm using adhesive tape, and the test piece was then fixed to a BA board. The 180-degree peel strength (N / 25 mm) of the adhesive PET laminated to the test piece was measured using a high-speed peel tester (manufactured by Tester Sangyo Co., Ltd.) at a peel speed of 15 m / min. (Evaluation criteria) ○…Less than 5N / 25mm ×…5N / 25mm or more, or peeling is not possible

[0084] <Adhesive strength> The adhesive tape with the release film on the back was cut to a width of 25 mm and a length of 120 mm, the release film was peeled off, and the adhesive layer side was attached to an adherend ((1) aluminum plate (manufactured by Nippon Test Panel Co., Ltd.; 1.0 mm thick)) by pressing it with a 2 kg rubber roller by moving it back and forth twice in an atmosphere of 23°C and relative humidity of 50%. After leaving it in the same atmosphere for 30 minutes, the 180-degree peel strength (N / 25 mm) was measured at a peel speed of 300 mm / min using a tensile tester (Shimadzu Autograph AG-X) and evaluated according to the following criteria. (Evaluation criteria) 〇...0.3N / 25mm or more × Less than 0.3N / 25mm

[0085] <Adhesion strength after 24 hours> The adhesive tape with the release film on the back was cut to a width of 25 mm and a length of 120 mm, the release film was peeled off, and the adhesive layer side was attached to an adherend ((1) aluminum plate (manufactured by Nippon Test Panel Co., Ltd.; 1.0 mm thick)) by pressing it with a 2 kg rubber roller by moving it back and forth twice in an atmosphere of 23°C and relative humidity of 50%. After leaving it in the same atmosphere for 24 hours, the 180-degree peel strength (N / 25 mm) was measured at a peel speed of 300 mm / min using a tensile tester (Shimadzu Autograph AG-X) and evaluated according to the following criteria. (Evaluation criteria) 〇...0.5N / 25mm or more × Less than 0.5N / 25mm

[0086] From the above results, the examples using an acrylic resin having a glass transition temperature equal to or higher than a specific temperature and a specific crosslinking agent were excellent in unwinding properties and adhesive strength. On the other hand, Comparative Example 1, which did not use a specific crosslinking agent, and Comparative Examples 2 and 3, which used an acrylic resin whose glass transition temperature was not higher than a specific temperature, had poor rewinding properties and adhesive strength, and the object of the present invention could not be achieved. [Industrial Applicability]

[0087] The adhesive composition for battery packaging of the present invention has excellent adhesive strength and rewindability from the back surface of a substrate that has not been subjected to a release treatment, and is therefore useful as a packaging material for batteries and battery cells.

Claims

1. A pressure-sensitive adhesive composition for battery packaging, comprising an acrylic resin (A) and a crosslinking agent (B), the acrylic resin (A) has a glass transition temperature of −30° C. or higher; The pressure-sensitive adhesive composition for battery packaging, wherein the crosslinking agent (B) contains a metal chelate crosslinking agent (b1).

2. 2. The pressure-sensitive adhesive composition for battery packaging materials according to claim 1, wherein the acrylic resin (A) has a weight average molecular weight of 100,000 to 2,000,000.

3. 2. The pressure-sensitive adhesive composition for battery packaging according to claim 1, wherein the content of the crosslinking agent (B) is 0.01 to 10 parts by mass per 100 parts by mass of the acrylic resin (A).

4. A pressure-sensitive adhesive for battery packaging, obtained by crosslinking the pressure-sensitive adhesive composition for battery packaging according to any one of claims 1 to 3.

5. 5. A pressure-sensitive adhesive for battery packaging materials, wherein the pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive for battery packaging materials according to claim 4 has an actually measured glass transition temperature of 0°C or higher.

6. A battery packaging material having an adhesive layer made of the adhesive for battery packaging material according to claim 4.

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