Adhesive sheet

Abstract

To provide an adhesive sheet which has excellent electrical conductivity and excellent reworkability, and is increased in the adhesive force with time, while having a small amount of outgas.SOLUTION: An adhesive sheet 1 according to the present invention comprises a metal base material 2 and an adhesive layer 3 that is arranged on at least one surface of the metal base material 2. The adhesive layer 3 contains, relative to 100 pts.mass of a polymer (A) that has a glass transition temperature of less than 0°C, 0.1 to 20 pts.mass of a polymer (B) that contains, as monomer units, a monomer (B1) having a polyorganosiloxane skeleton and a monomer (B2) having a homopolymer glass transition temperature of 40°C or more, wherein the monomer (B1) has a functional group equivalent (arithmetic average) of 1,000 g / mol or more and less than 15,000 g / mol and a weight average molecular weight of 10,000 or more and less than 100,000, and 0.4 pts.mass or more of a phenolic antioxidant.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to an adhesive sheet. [Background technology]

[0002] Lithium batteries, which have seen rapid growth as a power source for electronic devices including mobile devices, are also being put into practical use in electric vehicles (EVs). In addition to the load capacity, EVs urgently need to solve problems related to the electrolyte contained in batteries, such as deformation (swelling) and ignition during use. As a result, solid-state batteries have been expected to become widespread in recent years, and adhesive sheets (adhesive tapes) are used to fix circuit components of these batteries. Such adhesive sheets are required to have excellent conductivity.

[0003] Furthermore, if an adhesive sheet has high adhesive strength from the initial stage of adhesion, it becomes difficult to reposition. Therefore, there is a need for an adhesive sheet that has weak adhesive strength initially, but whose adhesive strength increases over time, resulting in high adhesive strength, in order to firmly fix the object to be attached.

[0004] Patent Document 1 discloses an adhesive composition that can form an adhesive layer that is initially weak in adhesive strength and can be easily peeled off from the adherend, i.e., has excellent reworkability, and whose adhesive strength increases over time. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-224227 [Overview of the project] [Problems that the invention aims to solve]

[0006] Adhesive sheets used to secure circuit components in solid-state batteries are required to have low outgassing rates, both from an environmental protection standpoint and to prevent ignition due to fire.

[0007] This invention was conceived under these circumstances, and its purpose is to provide an adhesive sheet that has excellent conductivity and reworkability, whose adhesive strength increases over time, and which produces little outgassing. [Means for solving the problem]

[0008] As a result of diligent research to achieve the above objectives, the inventors of this invention have found that an adhesive sheet comprising a metal substrate and a specific adhesive layer provided on at least one of its surfaces exhibits excellent conductivity and reworkability, increases in adhesive strength over time, and produces low outgassing. This invention was completed based on these findings.

[0009] In other words, the present invention comprises a metal substrate and an adhesive layer provided on at least one surface of the metal substrate. The adhesive layer described above provides an adhesive sheet comprising 100 parts by mass of polymer (A) having a glass transition temperature of less than 0°C, 0.1 to 20 parts by mass of polymer (B) having a polyorganosiloxane skeleton as monomer units (B1) and monomer (B2) having a homopolymer glass transition temperature of 40°C or higher, wherein the functional group equivalent (arithmetic mean) of monomer (B1) is 1000 g / mol or more and less than 15000 g / mol, and the weight-average molecular weight is 10000 or more and less than 100000, and 0.4 parts by mass or more of a phenolic antioxidant.

[0010] The above-mentioned phenolic antioxidant preferably contains a compound that includes two or more phenol skeletons.

[0011] The total outgassing amount of the above adhesive sheet is preferably 15,500 ppm or less.

[0012] The above adhesive sheet is preferably used for attaching battery components.

[0013] The above adhesive sheet is preferably used for attaching solid-state battery components.

[0014] The present invention also provides an electrode for an all-solid-state battery, comprising an insulating substrate, the adhesive sheet with the adhesive layer bonded to the insulating substrate, and an active material adhered to the metal substrate in the adhesive sheet.

Effects of the Invention

[0015] The adhesive sheet of the present invention is excellent in conductivity and reworkability, has an increasing adhesive force over time, and has a small outgassing amount. Therefore, the adhesive sheet is suitable for fixing circuit components of an all-solid-state battery, and since the outgassing amount generated at this time is small, ignition due to fire is unlikely to occur.

Brief Description of the Drawings

[0016] [Figure 1] It is a schematic cross-sectional view of an adhesive sheet according to an embodiment of the present invention. [Figure 2] It is a schematic cross-sectional view showing a method of manufacturing an electrode using the adhesive sheet shown in FIG. 1.

Modes for Carrying Out the Invention

[0017] <Adhesive Sheet> The adhesive sheet of the present invention comprises at least a metal substrate and an adhesive layer provided on at least one surface of the metal substrate. The adhesive sheet of the present invention may be a double-sided adhesive sheet in which both sides are surfaces of the adhesive layer, or may be a single-sided adhesive sheet in which only one side is the surface of the adhesive layer.

[0018] FIG. 1 is a schematic cross-sectional view showing an embodiment of the adhesive sheet of the present invention. As shown in FIG. 1, the adhesive sheet 1 is a single-sided adhesive sheet comprising a metal substrate 2 and an adhesive layer 3 provided on one surface of the metal substrate 2.

[0019] [Metal Substrate] The metal substrate is preferably a metal foil extending in the plane direction. The metal substrate may be a single layer or a multi-layer. In the case of a multi-layer, each layer may have the same constituent metal, thickness, etc., or may be different.

[0020] Examples of metals constituting the above-mentioned metal substrate include copper, aluminum, gold, nickel, titanium, molybdenum, niobium, tantalum, zirconium, and alloys. Examples of alloys include stainless steel, permalloy, and nichrome. From the viewpoint of obtaining excellent conductivity, copper is preferred as the above-mentioned metal. That is, copper foil is preferred as the above-mentioned metal substrate.

[0021] The method for forming the above-mentioned metal substrate is not particularly limited and includes, for example, electrolysis, vapor deposition (e.g., vacuum deposition), sputtering, CVD, metal-organic (MO), plating, and rolling.

[0022] The thickness of the above metal substrate is, for example, 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more. The thickness is, for example, 300 μm or less, preferably 200 μm or less, more preferably 100 μm or less, even more preferably 80 μm or less, and particularly preferably 50 μm or less.

[0023] [Adhesive layer] The adhesive layer described above comprises at least polymer (A), polymer (B), and a phenolic antioxidant. By using such an adhesive layer, the adhesive sheet of the present invention can be made to have low initial adhesive strength to the adherend and excellent reworkability, and whose adhesive strength increases over time, resulting in an adhesive sheet with excellent adhesion to the adherend.

[0024] The above adhesive layer contains 0.1 to 20 parts by mass of polymer (B) and 0.4 parts by mass or more of a phenolic antioxidant per 100 parts by mass of polymer (A). In this specification, the above adhesive layer may be referred to as "the adhesive layer of the present invention."

[0025] The adhesive sheet of the present invention may be a double-sided adhesive sheet or a single-sided adhesive sheet. If the adhesive sheet of the present invention comprises multiple adhesive layers, it is preferable that at least one adhesive layer is the adhesive layer of the present invention, and all adhesive layers are the adhesive layer of the present invention. Furthermore, the multiple adhesive layers may be identical, or they may be adhesive layers with different compositions, thicknesses, physical properties, etc.

[0026] (Polymer (A)) Polymer (A) is a polymer with a glass transition temperature of less than 0°C. By including such polymer (A) in the adhesive layer, sufficient adhesive strength can be achieved to the adherend over time.

[0027] Examples of polymer (A) include various polymers commonly used as adhesives, such as acrylic polymers, rubber polymers, silicone polymers, polyurethane polymers, and polyester polymers. In particular, when polymer (B) is a (meth)acrylic polymer, an acrylic polymer that is easily compatible with (meth)acrylic polymers and has high transparency is preferred. Polymer (A) may be used alone or in combination of two or more types.

[0028] The glass transition temperature (Tg) of polymer (A) is less than 0°C, preferably less than -10°C, and more preferably less than -30°C. Furthermore, a glass transition temperature of -80°C or higher is preferable. If the Tg of polymer (A) is 0°C or higher, the polymer may not flow easily, and the increase in adhesive strength over time may be less likely.

[0029] The glass transition temperature is either a nominal value listed in literature, catalogs, etc., or a value calculated based on the following formula (X) (Fox formula). 1 / Tg = W1 / Tg1 + W2 / Tg2 + ... + W n / Tg n (X) [In equation (X), Tg is the glass transition temperature of polymer (A) (unit: K), Tg i(i=1, 2, ...n) are the glass transition temperatures (in K) and W when monomer i forms a homopolymer. i (i=1, 2, ...n) represents the mass fraction of monomer i in the total monomer components. The above formula (X) is the calculation formula when polymer (A) is composed of n types of monomer components: monomer 1, monomer 2, ..., monomer n.

[0030] In this specification, "glass transition temperature (Tg) when a homopolymer is formed" (sometimes simply referred to as "Tg of the homopolymer") means "the glass transition temperature (Tg) of the monomer homopolymer," and specifically, the numerical value is given in the "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1987). For monomers not listed in the above literature, the Tg of the homopolymer refers to the value obtained by, for example, the following measurement method (see Japanese Patent Publication No. 2007-51271), except for monomers having a polyorganosiloxane skeleton. That is, 100 parts by mass of monomer, 0.2 parts by mass of 2,2'-azobisisobutyronitrile, and 200 parts by mass of ethyl acetate as a polymerization solvent are added to a reactor equipped with a thermometer, stirrer, nitrogen inlet tube, and reflux condenser, and the mixture is stirred for 1 hour while introducing nitrogen gas. After removing oxygen from the polymerization system in this way, the temperature is raised to 63°C and the reaction is carried out for 10 hours. Next, the mixture is cooled to room temperature to obtain a homopolymer solution with a solid content of 33% by mass. Then, this homopolymer solution is cast onto a release liner and dried to prepare a test sample (sheet-like homopolymer) with a thickness of approximately 2 mm. This test sample is then punched out into a disc shape with a diameter of 7.9 mm, sandwiched between parallel plates, and the viscoelasticity is measured using a viscoelasticity tester (product name "ARES", manufactured by Rheometrics) in shear mode while applying a shear strain of 1 Hz at a frequency of 1 Hz, in a temperature range of -70 to 150°C, with a heating rate of 5°C / min. The peak top temperature of tanδ is taken as the Tg of the homopolymer.

[0031] The weight-average molecular weight (Mw) of polymer (A) is 5 × 10 4 It is preferable that the number be greater than or equal to 10 × 104 More preferably, it is 20×10 4 More preferably, it is 30×10 4 or more. When the above Mw is 5×10 4 or more, it is easy to obtain an adhesive showing good cohesiveness. Further, the above Mw is preferably 500×10 4 or less. When the above Mw is 500×10 4 or less, it is easy to form an adhesive showing appropriate fluidity (mobility of polymer chains), so it is suitable for realizing an adhesive sheet having a low adhesive force at the initial stage of pasting and a high adhesive force after heating.

[0032] In the present specification, the Mw of the polymer (A) and the polymer (B) can be determined by gel permeation chromatography (GPC) in terms of polystyrene. More specifically, the Mw can be measured according to the methods and conditions described in the examples below.

[0033] The above acrylic polymer is a polymer containing an acrylic monomer (a monomer having a (meth)acryloyl group in the molecule) as a monomer component constituting the polymer. That is, the above acrylic polymer contains a structural unit derived from an acrylic monomer. The above acrylic polymer may contain only one kind of acrylic monomer as a monomer component, or may contain two or more kinds. In the present specification, "(meth)acrylic" represents "acrylic" and / or "methacrylic" (either one or both of "acrylic" and "methacrylic"), and the same applies to others.

[0034] The above acrylic polymer is preferably a polymer that contains the largest mass percentage of constituent units derived from (meth)acrylic acid ester. Examples of the above (meth)acrylic acid ester include hydrocarbon group-containing (meth)acrylic acid esters. Examples of the above hydrocarbon group-containing (meth)acrylic acid ester include alkyl (meth)acrylic acid esters having linear or branched aliphatic hydrocarbon groups, cycloalkyl (meth)acrylic acid esters having alicyclic hydrocarbon groups, and aryl (meth)acrylic acid esters having aromatic hydrocarbon groups. Only one type of hydrocarbon group-containing (meth)acrylic acid ester may be used, or two or more types may be used.

[0035] Examples of the above alkyl (meth)acrylate esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and methyl (meth)acrylate. Examples include isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (lauryl (meth)acrylate), tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate.

[0036] Among the above alkyl (meth)acrylate esters, alkyl (meth)acrylate esters having linear or branched aliphatic hydrocarbon groups with 1 to 20 carbon atoms (preferably 4 to 12, more preferably 6 to 10) are preferred. When the number of carbon atoms is within the above range, it is easy to adjust the glass transition temperature of the acrylic polymer and make it easier to achieve more appropriate tackiness.

[0037] As the alkyl (meth)acrylate ester mentioned above, it is preferable to use at least an alkyl (meth)acrylate ester having an alkyl group with 1 to 18 carbon atoms, more preferably an alkyl acrylate ester having an alkyl group with 1 to 14 carbon atoms (preferably 4 to 12, more preferably 6 to 10 carbon atoms), and particularly preferably n-butyl acrylate (BA) and / or 2-ethylhexyl acrylate (2EHA).

[0038] Examples of alkyl (meth)acrylate esters having an alkyl group with 1 to 18 carbon atoms include methyl acrylate, methyl methacrylate (MMA), n-butyl methacrylate (BMA), 2-ethylhexyl methacrylate (2EHMA), and isostearyl acrylate (ISTA).

[0039] Examples of (meth)acrylic acid esters having the above-mentioned alicyclic hydrocarbon group include (meth)acrylic acid esters having a monocyclic aliphatic hydrocarbon ring such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate; (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring such as isobornyl (meth)acrylate; and (meth)acrylic acid esters having three or more aliphatic hydrocarbon rings such as dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate.

[0040] Examples of (meth)acrylic acid esters having the above-mentioned aromatic hydrocarbon group include phenyl (meth)acrylate and benzyl (meth)acrylate.

[0041] In order to appropriately exhibit the basic properties such as tackiness of the hydrocarbon group-containing (meth)acrylic acid ester in the adhesive layer, the proportion of the hydrocarbon group-containing (meth)acrylic acid ester in the total monomer components constituting the acrylic polymer is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, based on the total amount (100% by mass) of the total monomer components. Furthermore, from the viewpoint of enabling copolymerization with other monomer components and obtaining the effects of those other monomer components, the above proportion may be 99.9% by mass or less, 98% by mass or less, 95% by mass or less, 90% by mass or less, or 80% by mass or less.

[0042] The above acrylic polymer may contain constituent units derived from other monomer components copolymerizable with the hydrocarbon group-containing (meth)acrylic acid ester, for the purpose of modifying it to improve cohesiveness or introduce crosslinking points. Examples of the above other monomer components include polar group-containing monomers such as carboxyl group-containing monomers, acid anhydride monomers, hydroxyl group-containing monomers, glycidyl group-containing monomers, sulfonic acid group-containing monomers, phosphate group-containing monomers, and nitrogen atom-containing monomers. Each of the above other monomer components may be used individually or in combination of two or more.

[0043] Examples of the above carboxyl group-containing monomers include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Examples of the above acid anhydride monomers include maleic anhydride and itaconic anhydride.

[0044] Examples of the above-mentioned hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate.

[0045] Examples of the above-mentioned glycidyl group-containing monomers include glycidyl (meth)acrylate and methylglycidyl (meth)acrylate.

[0046] Examples of the above-mentioned sulfonic acid group-containing monomers include styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid.

[0047] Examples of the above-mentioned phosphate group-containing monomers include 2-hydroxyethyl acryloyl phosphate.

[0048] The above-mentioned nitrogen atom-containing monomer is a monomer (monomer) that has at least one nitrogen atom within its molecule (one molecule). While the nitrogen atom-containing monomer is not particularly limited, cyclic nitrogen-containing monomers and (meth)acrylamides are preferred examples. Note that only one type of nitrogen atom-containing monomer may be used, or two or more types may be used.

[0049] The above-mentioned cyclic nitrogen-containing monomer is not particularly limited as long as it has a polymerizable functional group having an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and has a cyclic nitrogen structure. The above-mentioned cyclic nitrogen structure is preferably one in which a nitrogen atom is contained within the cyclic structure.

[0050] Examples of the cyclic nitrogen-containing monomers mentioned above include N-vinyl cyclic amides (lactam-based vinyl monomers) and vinyl monomers having nitrogen-containing heterocycles.

[0051] Examples of the above-mentioned N-vinylcyclic amides include N-vinylcyclic amides represented by the following formula (1). [ka] (In formula (1), R 1 (This indicates a divalent organic group.)

[0052] R in equation (1) above 1 is a divalent organic group, preferably a divalent saturated hydrocarbon group or an unsaturated hydrocarbon group, and more preferably a divalent saturated hydrocarbon group (for example, an alkylene group having 3 to 5 carbon atoms).

[0053] Examples of N-vinyl cyclic amides represented by formula (1) above include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, and N-vinyl-3,5-morpholindione.

[0054] Examples of vinyl monomers having nitrogen-containing heterocycles include acrylic monomers having nitrogen-containing heterocycles such as morpholine rings, piperidine rings, pyrrolidine rings, and piperazine rings.

[0055] The above-mentioned vinyl monomers having a nitrogen-containing heterocycle are not particularly limited, but examples include (meth)acryloylmorpholine, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole, N-vinylpyrazine, N-vinylmorpholine, N-vinylpyrazole, vinylpyridine, vinylpyrimidine, vinyloxazole, vinylisoxazole, vinylthiazole, vinylisothiazole, vinylpyridazine, (meth)acryloylpyrrolidone, (meth)acryloylpyrrolidine, and (meth)acryloylpiperidine.

[0056] Examples of the above (meth)acrylamides include (meth)acrylamide, N-alkyl(meth)acrylamide, and N,N-dialkyl(meth)acrylamide. Examples of the above N-alkyl(meth)acrylamides include N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, Nn-butyl(meth)acrylamide, and N-octyl(meth)acrylamide. Furthermore, the above N-alkyl(meth)acrylamides also include (meth)acrylamides having an amino group, such as dimethylaminoethyl(meth)acrylamide, diethylaminoethyl(meth)acrylamide, and dimethylaminopropyl(meth)acrylamide. Examples of the above-mentioned N,N-dialkyl(meth)acrylamides include N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, and N,N-di(t-butyl)(meth)acrylamide.

[0057] Furthermore, the above-mentioned (meth)acrylamides also include, for example, various N-hydroxyalkyl (meth)acrylamides. Examples of the above-mentioned N-hydroxyalkyl (meth)acrylamides include N-methylol(meth)acrylamide, N-(2-hydroxyethyl)(meth)acrylamide, N-(2-hydroxypropyl)(meth)acrylamide, N-(1-hydroxypropyl)(meth)acrylamide, N-(3-hydroxypropyl)(meth)acrylamide, N-(2-hydroxybutyl)(meth)acrylamide, N-(3-hydroxybutyl)(meth)acrylamide, N-(4-hydroxybutyl)(meth)acrylamide, and N-methyl-N-2-hydroxyethyl(meth)acrylamide.

[0058] Furthermore, the above-mentioned (meth)acrylamides also include, for example, various N-alkoxyalkyl(meth)acrylamides. Examples of the above-mentioned N-alkoxyalkyl(meth)acrylamides include N-methoxymethyl(meth)acrylamide and N-butoxymethyl(meth)acrylamide.

[0059] Furthermore, examples of nitrogen atom-containing monomers other than the above-mentioned cyclic nitrogen-containing monomers and (meth)acrylamides include amino group-containing monomers, cyano group-containing monomers, imide group-containing monomers, and isocyanate group-containing monomers. Examples of the above-mentioned amino group-containing monomers include (meth)acrylate aminoethyl, (meth)acrylate dimethylaminoethyl, (meth)acrylate dimethylaminopropyl, and (meth)acrylate t-butylaminoethyl. Examples of the above-mentioned cyano group-containing monomers include acrylonitrile and methacrylonitrile. Examples of the above-mentioned imide group-containing monomers include maleimide monomers (e.g., N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, etc.), itaconimide monomers (e.g., N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-laurylitaconimide, N-cyclohexylitaconimide, etc.), and succinimide monomers (e.g., N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, N-(meth)acryloyl-8-oxyoctamethylenesuccinimide, etc.). Examples of the above-mentioned isocyanate group-containing monomers include 2-(meth)acryloyloxyethyl isocyanate.

[0060] Among the nitrogen atom-containing monomers mentioned above, cyclic nitrogen-containing monomers are preferred, and N-vinyl cyclic amides are more preferred. More specifically, N-vinyl-2-pyrrolidone (NVP) and N-vinyl-2-caprolactam are particularly preferred.

[0061] It is preferable that the polar group-containing monomer constituting the above acrylic polymer includes a hydroxyl group-containing monomer and / or a nitrogen atom-containing monomer. By using such polar group-containing monomers, the cohesive force and polarity of the adhesive can be adjusted, and the adhesive strength after heating can be improved.

[0062] When the above acrylic polymer contains the above hydroxyl group-containing monomer as a monomer component constituting the polymer, the proportion of the above hydroxyl group-containing monomer in the total monomer components (100% by mass) constituting the above acrylic polymer is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, even more preferably 1% by mass or more, even more preferably 5% by mass or more, and particularly preferably 10% by mass or more. Furthermore, the proportion of the above nitrogen atom-containing monomer is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and may be 10% by mass or less or 5% by mass or less, from the viewpoint of improving tackiness at room temperature (25°C) and improving flexibility at low temperatures.

[0063] When the above acrylic polymer contains the nitrogen atom-containing monomer as a monomer component constituting the polymer, the proportion of the nitrogen atom-containing monomer in the total monomer components (100% by mass) constituting the acrylic polymer is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, even more preferably 1% by mass or more, even more preferably 5% by mass or more, and particularly preferably 10% by mass or more. Furthermore, from the viewpoint of improving tackiness at room temperature (25°C) and improving flexibility at low temperatures, the proportion of the nitrogen atom-containing monomer is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0064] The total proportion of the polar group-containing monomers (especially the sum of the nitrogen atom-containing monomers and the hydroxyl group-containing monomers) in the total monomer components (100% by mass) constituting the above acrylic polymer is not particularly limited, but from the viewpoint of better exhibiting the effects of using polar group-containing monomers, it is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 5% by mass or more, and may be 10% by mass or more, 15% by mass or more, 20% by mass or more, or 25% by mass or more. Furthermore, from the viewpoint of obtaining an adhesive layer with appropriate flexibility, the total proportion is preferably 50% by mass or less, and more preferably 40% by mass or less.

[0065] The monomer components constituting the above-mentioned acrylic polymer may further include other monomers. Examples of these other monomers include vinyl ester monomers such as vinyl acetate, vinyl propionate, and vinyl laurate; aromatic vinyl compounds such as styrene, substituted styrene (α-methylstyrene, etc.), and vinyltoluene; olefin monomers such as ethylene, propylene, isoprene, butadiene, and isobutylene; chlorine-containing monomers such as vinyl chloride and vinylidene chloride; alkoxy group-containing monomers such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; and vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether.

[0066] The proportion of the other monomers in the total amount of all monomer components constituting the above acrylic polymer (100% by mass) may be, for example, 0.05% by mass or more, or 0.5% by mass or more. The above proportion may also be, for example, 20% by mass or less, 10% by mass or less, or 5% by mass or less, and may be substantially absent.

[0067] The above-mentioned acrylic polymer is obtained by polymerizing the various monomer components described above. The polymerization method is not particularly limited, but examples include solution polymerization, emulsion polymerization, bulk polymerization, and polymerization by active energy ray irradiation (active energy ray polymerization). Furthermore, the resulting acrylic polymer may be a random copolymer, block copolymer, graft copolymer, or any other type.

[0068] Various common solvents may be used in the polymerization of monomer components. Examples of such solvents include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. One or more of these solvents may be used.

[0069] The polymerization initiators, chain transfer agents, emulsifiers, etc., used in the radical polymerization of monomer components are not particularly limited and can be selected and used as appropriate. The weight-average molecular weight of the acrylic polymer can be controlled by the amount of polymerization initiator and chain transfer agent used and the reaction conditions, and the appropriate amounts used are adjusted according to the type of agent.

[0070] Depending on the type of polymerization reaction, various polymerization initiators can be used for the polymerization of monomer components, including thermal polymerization initiators and photopolymerization initiators (photoinitiators). One type of polymerization initiator may be used, or two or more types may be used.

[0071] The above-mentioned thermal polymerization initiators are not particularly limited, but examples include azo polymerization initiators, peroxide polymerization initiators (e.g., persulfates such as dibenzoyl peroxide, tert-butyl permaleate, potassium persulfate, benzoyl peroxide, hydrogen peroxide, etc.), substituted ethane initiators such as phenyl-substituted ethane, aromatic carbonyl compounds, redox polymerization initiators, etc. Among these, the azo polymerization initiator disclosed in Japanese Patent Application Publication No. 2002-69411 is preferred. Examples of the above-mentioned azo polymerization initiators include 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2-methylpropionic acid)dimethyl, and 4,4'-azobis-4-cyanovaleric acid. The amount of thermal polymerization initiator used can be the usual amount, for example, it can be selected from a range of 0.01 to 5 parts by mass, preferably 0.05 to 3 parts by mass, per 100 parts by mass of monomer component.

[0072] The above-mentioned photopolymerization initiators are not particularly limited, but examples include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, and thioxanthone-based photopolymerization initiators. Other examples include acylphosphine oxide-based photopolymerization initiators and titanocene-based photopolymerization initiators. Examples of the above-mentioned benzoin ether-based photopolymerization initiators include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one, and anisole methyl ether. Examples of the above acetophenone-based photopolymerization initiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 4-phenoxydichloroacetophenone, and 4-(t-butyl)dichloroacetophenone. Examples of the above α-ketol-based photopolymerization initiators include 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one. Examples of the above aromatic sulfonyl chloride-based photopolymerization initiators include 2-naphthalenesulfonyl chloride. Examples of the above photoactive oxime-based photopolymerization initiators include 1-phenyl-1,1-propanedione-2-(O-ethoxycarbonyl)-oxime. Examples of the above benzoin-based photopolymerization initiators include benzoin. Examples of the above benzyl-based photopolymerization initiators include benzyl. Examples of the benzophenone-based photopolymerization initiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexylphenyl ketone. Examples of the ketal-based photopolymerization initiators include benzyldimethyl ketal.Examples of the thioxanthone-based photopolymerization initiators include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone. Examples of the acylphosphine oxide-based photopolymerization initiators include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide. Examples of the titanocene-based photopolymerization initiators include bis(η. 5 Examples include -2,4-cyclopentadiene-1-yl)bis(2,6-difluoro-3-(1H-pyrrole-1-yl)-phenyl)titanium. The amount of photopolymerization initiator used can be the usual amount, for example, it can be selected from a range of 0.01 to 5 parts by mass, preferably 0.05 to 3 parts by mass, per 100 parts by mass of monomer component.

[0073] The above-mentioned acrylic polymer may be included in an adhesive composition for forming an adhesive layer in the form of a partially polymerized product (acrylic polymer syrup) obtained by irradiating a monomer composition containing a polymerization initiator with the monomer components described above with ultraviolet light (UV) to polymerize a portion of the monomer components. The adhesive composition containing the above-mentioned acrylic polymer syrup can be applied to a substrate to be coated, such as a metal substrate or a release liner, and the polymerization can be completed by irradiating it with ultraviolet light. In other words, the above-mentioned acrylic polymer syrup may be a precursor of an acrylic polymer. The above-mentioned adhesive layer can be formed, for example, using an adhesive composition containing the above-mentioned acrylic polymer syrup, polymer (B), and a phenolic antioxidant.

[0074] (Polymer (B)) Polymer (B) contains monomers (B1) having a polyorganosiloxane skeleton and monomers (B2) having a homopolymer glass transition temperature of 40°C or higher as monomer units.

[0075] The monomer (B1) having a polyorganosiloxane skeleton that constitutes the polymer (B) is not particularly limited, and any polyorganosiloxane skeleton-containing monomer can be used. Due to the low polarity derived from its structure, monomer (B1) actively promotes the uneven distribution of polymer (B) on the adherend surface, resulting in easy peelability in the initial stages of bonding.

[0076] Examples of monomers having a polyorganosiloxane skeleton that can be used as monomer (B1) include the compounds represented by the following formula (2) and the compounds represented by the following formula (3). More specifically, examples include single-ended reactive silicone oils such as the trade names "X-22-174ASX", "X-22-2475", "X-22-174DX", "X-22-2426", and "KF-2012" (all manufactured by Shin-Etsu Chemical Co., Ltd.). Monomer (B1) may be used by one type only, or by two or more types.

[0077] [ka] [In formulas (2) and (3), R 2 R represents a hydrogen atom or a methyl group. 3 [where represents a monovalent organic group, and m and n are independent integers of 0 or greater.]

[0078] Examples of the monovalent organic group mentioned above include linear or branched hydrocarbon groups. The hydrocarbon group is either saturated or unsaturated. The monovalent organic group preferably has 1 to 10 carbon atoms, and more preferably 1 to 4 carbon atoms. Among the monovalent organic groups, methyl groups, ethyl groups, propyl groups (n-propyl groups, isopropyl groups), and butyl groups (n-butyl groups, t-butyl groups, etc.) are particularly preferred.

[0079] The functional group equivalent of monomer (B1) is 1000 g / mol or more and less than 15000 g / mol. If the functional group equivalent is less than 1000 g / mol, light peelability may not be exhibited, and the tackiness may not decrease in the initial stages of bonding. Furthermore, if the functional group equivalent is 15000 g / mol or more, the compatibility with polymer (A) deteriorates significantly, and the tackiness may not decrease in the initial stages of bonding with the adherend, or the increase in tackiness over time may be poor.

[0080] Here, "functional group equivalent" refers to the mass of the main skeleton (e.g., polydimethylsiloxane) bonded to each functional group. The unit g / mol is calculated by converting 1 mol of functional group to g / mol. The functional group equivalent of a monomer having a polyorganosiloxane skeleton can be obtained, for example, by nuclear magnetic resonance (NMR) analysis. 1 It is calculated from the spectral intensity of 1H-NMR (proton NMR).

[0081] 1Using 1H-NMR, the ratio of the spectral intensity of H atoms bonded to silicon in a siloxane structure via C (e.g., H in Si-(CH3)2) to the spectral intensity of H atoms in functional groups such as C-CH3, SH, or C=CH2 is determined. For example, if the ratio of the spectral intensity of H atoms in a siloxane structure to H atoms in a functional group such as C=CH2 is determined, the ratio of the number of Si-(CH3)2 siloxane structures to the number of C=CH2 functional groups in the sample can be determined from the spectral intensity ratio. Since the chemical formulas of the siloxane structure and the functional groups are known beforehand, the ratio of the number of Si-(CH3)2 siloxane structures to the number of C=CH2 functional groups (A / B) in the sample can be determined from the ratio of the number of siloxane structures A with Si-(CH3)2 bonds to the number of C=CH2 functional groups. Since the molecular weight of each siloxane structure containing a Si-(CH3)2 bond (in this case, dimethylsiloxane) is known, multiplying that molecular weight by the ratio (A / B) of the number of siloxane structures to the number of functional groups gives the mass of each siloxane structure containing a Si-(CH3)2 bond, i.e., the mass of the main skeleton. Multiplying this mass by Avogadro's number gives the functional group equivalent (g / mol).

[0082] Furthermore, when using monomers having two or more polyorganosiloxane skeletons with different functional group equivalents, the functional group equivalent of monomer (B1) shall be the arithmetic mean of the functional group equivalents of the two or more polyorganosiloxane skeleton monomers. For example, when using monomers having n types of polyorganosiloxane skeletons (monomer 1, monomer 2, ... monomer n), the value calculated by the following formula shall be the functional group equivalent of monomer (B1). Functional group equivalent weight (g / mol) of monomer (B1) = (Functional group equivalent weight of monomer 1 × Amount of monomer 1 + Functional group equivalent weight of monomer 2 × Amount of monomer 2 + ... + Functional group equivalent weight of monomer n × Amount of monomer n) / (Amount of monomer 1 + Amount of monomer 2 + ... + Amount of monomer n)

[0083] The proportion of monomer (B1) in the total monomer components constituting polymer (B) is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and particularly preferably 20% by mass or more, based on the total amount (100% by mass) of the above monomer components, from the viewpoint of exhibiting appropriate initial tackiness and better exhibiting the effect of a tackiness increase retarder. The proportion of monomer (B1) is preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, and particularly preferably 30% by mass or less, based on the total amount (100% by mass) of the above monomer components, from the viewpoint of excellent polymerization reactivity and compatibility, and superior tackiness increase over time.

[0084] The monomer (B2) constituting polymer (B) has a homopolymer glass transition temperature of 40°C or higher, preferably 80°C or higher, and more preferably 100°C or higher. Monomer (B2) may be used alone or two or more types.

[0085] Examples of monomer (B2) include acrylic monomers and polar group-containing monomers. Specifically, monomer (B2) refers to monomers among the above-mentioned acrylic monomers and polar group-containing monomers in which the glass transition temperature of the homopolymer is 40°C or higher.

[0086] As the monomer (B2), which is an acrylic monomer, (meth)acrylic acid esters having hydrocarbon groups are preferred, and alkyl (meth)acrylic acid esters having linear or branched aliphatic hydrocarbon groups and (meth)acrylic acid esters having alicyclic hydrocarbon groups are more preferred.

[0087] Examples of acrylic monomers (B2) include dicyclopentanyl methacrylate (Tg: 175°C), dicyclopentanyl acrylate (Tg: 120°C), isobornyl methacrylate (Tg: 173°C), isobornyl acrylate (Tg: 97°C), methyl methacrylate (Tg: 105°C), 1-adamantyl methacrylate (Tg: 250°C), and 1-adamantyl acrylate (Tg: 153°C).

[0088] Examples of monomers (B2) that contain polar groups include amide group-containing monomers such as acryloylmorpholine (Tg: 145°C), dimethylacrylamide (Tg: 119°C), diethylacrylamide (Tg: 81°C), dimethylaminopropylacrylamide (Tg: 134°C), isopropylacrylamide (Tg: 134°C), and hydroxyethylacrylamide (Tg: 98°C); and nitrogen atom-containing monomers such as lactam monomers like N-vinyl-2-caprolactam.

[0089] When monomer (B2) is a monomer containing a polar group, polymer (B) preferably contains an acrylic monomer as a monomer component constituting polymer (B), in addition to monomer (B1) and monomer (B2).

[0090] The proportion of monomer (B2) in the total monomer components constituting polymer (B) is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, relative to the total amount (100% by mass) of the above monomer components, from the viewpoint of exhibiting appropriate initial tackiness and better exhibiting the effect as a tackiness increase retarder. If the above proportion is 10% by mass or more, the initial tackiness tends to decrease. The proportion of monomer (B2) is preferably 80% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less, relative to the total amount (100% by mass) of the above monomer components, from the viewpoint of excellent polymerization reactivity and compatibility, and superior tackiness increase over time.

[0091] Polymer (B) may contain monomers other than monomers (B1) and monomer (B2) as monomer components. Examples of these other monomers include those listed above as monomers constituting the acrylic polymer but not corresponding to monomers (B1) and monomer (B2). Preferably, these other monomers include monomers having a homopolymer glass transition temperature of less than 40°C (sometimes referred to as "monomer (B3)"). Monomer (B3) has a homopolymer glass transition temperature of less than 40°C, preferably 35°C or lower, more preferably 30°C or lower. Monomer (B3) may be of one type or two or more types.

[0092] Examples of monomers (B3) include acrylic monomers. Specifically, monomers (B3) are those among the acrylic monomers mentioned above whose homopolymer glass transition temperature is less than 40°C. Examples of acrylic monomers (B3) include alkyl methacrylates such as butyl methacrylate (Tg: 20°C) and 2-ethylhexyl methacrylate (Tg: -10°C).

[0093] The proportion of monomer (B3) in the total monomer components constituting polymer (B) is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, based on the total amount of all monomer components (100% by mass). The above proportion is preferably 85% by mass or less, more preferably 70% by mass or less, even more preferably 55% by mass or less, and particularly preferably 50% by mass or less, based on the total amount of all monomer components (100% by mass).

[0094] The total proportion of monomers (B1) and (B2) in the total monomer components constituting polymer (B) is preferably 15% by mass or more, more preferably 30% by mass or more, even more preferably 45% by mass or more, and particularly preferably 50% by mass or more, based on the total amount of all monomer components (100% by mass). The total proportion is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less, based on the total amount of all monomer components (100% by mass).

[0095] The weight-average molecular weight of polymer (B) is 10,000 or more and less than 100,000, preferably 12,000 or more and less than 50,000, and more preferably 15,000 or more and less than 30,000. If the weight-average molecular weight of polymer (B) is 100,000 or more, the adhesive strength will not decrease in the initial stages of bonding. On the other hand, if the weight-average molecular weight is less than 10,000, the low molecular weight may prevent the adhesive strength of the adhesive sheet from increasing over time.

[0096] Polymer (B) can be obtained, for example, by polymerizing the various monomer components described above. The polymerization method is not particularly limited, but examples include solution polymerization, emulsion polymerization, bulk polymerization, and polymerization by active energy ray irradiation (active energy ray polymerization).

[0097] In the polymerization described above, a chain transfer agent may be used to adjust the molecular weight of polymer (B). Examples of such chain transfer agents include compounds having a mercapto group, such as octyl mercaptan, lauryl mercaptan, t-nonyl mercaptan, t-dodecyl mercaptan, mercaptoethanol, and α-thioglycerol; thioglycolic acid esters, such as thioglycolic acid, methyl thioglycolate, ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, isooctyl thioglycolate, decyl thioglycolate, dodecyl thioglycolate, thioglycolic acid ester of ethylene glycol, thioglycolic acid ester of neopentyl glycol, and thioglycolic acid ester of pentaerythritol; and α-methylstyrene dimer. One or more of these chain transfer agents may be used.

[0098] The amount of the chain transfer agent used is, for example, 0.05 to 20 parts by mass, preferably 0.1 to 15 parts by mass, and more preferably 0.2 to 10 parts by mass, per 100 parts by mass of the monomer component.

[0099] The content of polymer (B) in the adhesive layer is 0.1 to 20 parts by mass, preferably 0.3 to 25 parts by mass, more preferably 0.4 to 20 parts by mass, even more preferably 0.5 to 15 parts by mass, even more preferably 1 to 10 parts by mass, and particularly preferably 2 to 7 parts by mass, based on 100 parts by mass of the total amount of polymer (A). A content of 0.1 parts by mass or more provides excellent reworkability. A content of 20 parts by mass or less allows for high adhesive strength after heating.

[0100] The adhesive layer described above may contain other polymers other than polymer (A) and polymer (B) to the extent that it does not impair the effects of the present invention. The content of the other polymers is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, based on 100% by mass of the total amount of polymer components contained in the adhesive layer, and may also be 5% by mass or less, 3% by mass or less, or 1% by mass or less. It is preferable that the adhesive layer is substantially free of the other polymers described above.

[0101] (Phenol-based antioxidants) The adhesive layer described above contains polymer (A) and polymer (B) in addition to a phenolic antioxidant. The phenolic antioxidant is presumed to have the function of capturing components that may outgasse in the adhesive layer, and by including it in a certain amount or more, the total amount of outgassing in the adhesive layer is reduced. The phenolic antioxidant may be used by one type only, or by using two or more types.

[0102] The number of phenolic skeletons in the above-mentioned phenolic antioxidant is not particularly limited, but is 1 or more (for example, 1 to 10), preferably 2 or more, more preferably 3 or more, and even more preferably 4 or more. A larger number of phenolic skeletons leads to a further reduction in total outgassing.

[0103] Specific examples of the above phenolic antioxidants include 2,6-di-t-butyl-p-cresol, 2,6-di-t-butyl-4-ethylphenol, 2,6-dicyclohexyl-4-methylphenol, 2,6-diisopropyl-4-ethylphenol, 2,6-di-t-amyl-4-methylphenol, 2,6-di-t-octyl-4-n-propylphenol, 2,6-dicyclohexyl-4-n-octylphenol, 2-isopropyl-4-methyl-6-t-butylphenol, and 2-t-butyl-4-ethyl-6-t-octyl Compounds having one phenol skeleton (monocyclic phenol compounds) such as 2,2'-methylenebis(4-methyl-6-)- 2,2'-methylenebis(4-methyl-6-)- 2,2'-methylenebis(4-methyl-6-)- 2,2'-methylenebis(4-methyl-6-) t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 2,2'-thiobis(4-methyl-6-t-butylphenol), 4,4'-methylenebis(2,6-di-t-butylphenol), 2,2'-methylenebis[6-(1-methylcyclohexyl)-p-cresol], 2,2'-ethylidenebis(4,6-di-t-butylphenol), 2,2'-butylidenebis(2-t-butyl-4-methylphenol), 3 Compounds having two phenol skeletons (bicyclic phenol compounds) such as ,6-dioxaoctamethylenebis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate], triethylene glycolbis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediolbis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], and 2,2'-thiodiethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate];1,1,3-Tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-Tris(2,6-dimethyl-3-hydroxy-4-t-butylbenzyl)isocyanurate, 1,3,5-Tris[(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxyethyl]isocyanurate, Tris(4-t-butyl-2,6-dimethyl-3-hydroxybenzyl)isocyanurate, 1,3,5-trimethyl-2,4,6-Tris(3,5-di-t-butyl-4-hydroxyphenyl) Examples include compounds having three phenolic skeletons, such as roxybenzylbenzene (tri-ring phenol compounds); compounds having four phenolic skeletons, such as tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane (tetra-ring phenol compounds); and phosphorus-containing phenol compounds such as bis(3,5-di-t-butyl-4-hydroxybenzylphosphonate ethyl)calcium and bis(3,5-di-t-butyl-4-hydroxybenzylphosphonate ethyl)nickel.

[0104] The content of the phenolic antioxidant in the adhesive layer is 0.4 parts by mass or more, preferably 0.5 parts by mass or more, and more preferably 0.7 parts by mass or more, per 100 parts by mass of the total amount of polymer (A). A content of 0.4 parts by mass or more reduces the total outgassing amount of the adhesive sheet. The content is preferably less than 5 parts by mass, more preferably 4 parts by mass or less, and even more preferably 3 parts by mass or less. A content of less than 5 parts by mass makes segregation on the surface of the adhesive layer less likely, reducing solidification of the adhesive layer surface and the resulting decrease in adhesive strength after heating. Furthermore, it provides excellent dispersibility in the adhesive composition forming the adhesive layer.

[0105] Polymers (A) and (B) may be crosslinked with a crosslinking agent. By using a crosslinking agent, a crosslinked structure can be formed in the polymer components of the adhesive layer, and the cohesive force can be controlled. The crosslinking agent is appropriately selected according to the functional groups that polymer components such as polymer (A) and polymer (B) have in their side chains. Only one crosslinking agent may be used, or two or more may be used.

[0106] The above crosslinking agents are not particularly limited, but examples include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, amine-based crosslinking agents, hydrazine-based crosslinking agents, silicone-based crosslinking agents, and silane-based crosslinking agents (silane coupling agents). Among the above crosslinking agents, it is preferable to include isocyanate-based crosslinking agents.

[0107] The content of the crosslinking agent is not particularly limited, but is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, even more preferably 0.5 parts by mass or more, and especially preferably 1 part by mass or more, per 100 parts by mass of the total amount of polymer (A). When the content is 0.01 parts by mass or more, the reworkability is better. Furthermore, the content of the crosslinking agent is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less.

[0108] The above-mentioned isocyanate-based crosslinking agent is a compound having an average of two or more isocyanate groups per molecule (polyfunctional isocyanate compound). Examples of the above-mentioned isocyanate-based crosslinking agent include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, and the like.

[0109] Examples of the above-mentioned aliphatic polyisocyanates include 1,2-ethylene diisocyanate; tetramethylene diisocyanates such as 1,2-tetramethylene diisocyanate, 1,3-tetramethylene diisocyanate, and 1,4-tetramethylene diisocyanate; hexamethylene diisocyanates such as 1,2-hexamethylene diisocyanate, 1,3-hexamethylene diisocyanate, 1,4-hexamethylene diisocyanate, 1,5-hexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, and 2,5-hexamethylene diisocyanate; and 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, and lysine diisocyanate.

[0110] Examples of the above-mentioned alicyclic polyisocyanates include isophorone diisocyanate; cyclohexyl diisocyanates such as 1,2-cyclohexyl diisocyanate, 1,3-cyclohexyl diisocyanate, and 1,4-cyclohexyl diisocyanate; cyclopentyl diisocyanates such as 1,2-cyclopentyl diisocyanate and 1,3-cyclopentyl diisocyanate; hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

[0111] Examples of the above aromatic polyisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, and 2,2'-diphenylpropane-4,4'-diisocyanate. Examples include 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropanediisocyanate, m-phenylenediisocyanate, p-phenylenediisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, xylylene-1,4-diisocyanate, and xylylene-1,3-diisocyanate.

[0112] In addition, commercially available isocyanate-based crosslinking agents include, for example, trimethylolpropane / tolylene diisocyanate adduct (product name "Coronate L", manufactured by Tosoh Corporation), trimethylolpropane / hexamethylene diisocyanate adduct (product name "Coronate HL", manufactured by Tosoh Corporation), and trimethylolpropane / xylylene diisocyanate adduct (product name "Takenate D-110N", manufactured by Mitsui Chemicals, Inc.).

[0113] Examples of the epoxy crosslinking agents (polyfunctional epoxy compounds) mentioned above include N,N,N',N'-tetraglycidyl-m-xylenediline, diglycidylaniline, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and sorbitol polyglycidyl ether. Examples of epoxy crosslinking agents include diglycidyl ethers, glycerol polyglycidyl ethers, pentaerythritol polyglycidyl ethers, polyglycerol polyglycidyl ethers, sorbitan polyglycidyl ethers, trimethylolpropane polyglycidyl ethers, diglycidyl adipate esters, diglycidyl o-phthalate esters, triglycidyl-tris(2-hydroxyethyl) isocyanurate, resorcinol diglycidyl ethers, bisphenol-S-diglycidyl ethers, and epoxy resins having two or more epoxy groups in their molecules. In addition, commercially available epoxy crosslinking agents such as the trade name "Tetrad C" (manufactured by Mitsubishi Gas Chemical Company, Inc.) can also be used.

[0114] As the above-mentioned peroxide-based crosslinking agent, any agent that generates radical active species upon heat to promote crosslinking of the base polymer can be used as appropriate. However, considering workability and stability, it is preferable to use a peroxide with a 1-minute half-life temperature of 80 to 160°C, and more preferably a peroxide with a half-life temperature of 90 to 140°C.

[0115] Examples of the above peroxide-based crosslinking agents include di(2-ethylhexyl)peroxydicarbonate (half-life temperature at 1 minute: 90.6°C), di(4-t-butylcyclohexyl)peroxydicarbonate (half-life temperature at 1 minute: 92.1°C), di-sec-butylperoxydicarbonate (half-life temperature at 1 minute: 92.4°C), t-butylperoxyneodecanoate (half-life temperature at 1 minute: 103.5°C), t-hexylperoxypivalate (half-life temperature at 1 minute: 109.1°C), t-butylperoxypivalate (half-life temperature at 1 minute: 110.3°C), and dilauroyl peroxy Examples include peroxide (half-life temperature at 1 minute: 116.4°C), di-n-octanoyl peroxide (half-life temperature at 1 minute: 117.4°C), 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate (half-life temperature at 1 minute: 124.3°C), di(4-methylbenzoyl) peroxide (half-life temperature at 1 minute: 128.2°C), dibenzoyl peroxide (half-life temperature at 1 minute: 130.0°C), t-butyl peroxyisobutyrate (half-life temperature at 1 minute: 136.1°C), and 1,1-di(t-hexylperoxy)cyclohexane (half-life temperature at 1 minute: 149.2°C).

[0116] The half-life of the peroxide-based crosslinking agent mentioned above is an indicator of the decomposition rate of the peroxide, and refers to the time it takes for the amount of remaining peroxide to be halved. The decomposition temperature required to obtain a half-life at any given time, and the half-life time at any given temperature, are described in manufacturer catalogs, for example, in NOF Corporation's "Organic Peroxide Catalog, 9th Edition (May 2003)". The amount of remaining decomposed peroxide after reaction treatment can be measured, for example, by HPLC (High-Performance Liquid Chromatography). More specifically, for example, approximately 0.2 g of the adhesive after reaction treatment is taken, immersed in 10 ml of ethyl acetate, and extracted by shaking at 120 rpm at 25°C for 3 hours, then left to stand at room temperature for 3 days. Next, 10 ml of acetonitrile is added, shaken at 120 rpm at 25°C for 30 minutes, filtered through a membrane filter (0.45 μm), and approximately 10 μl of the resulting extract is injected into HPLC for analysis to determine the amount of peroxide after reaction treatment.

[0117] Furthermore, organic crosslinking agents or polyfunctional metal chelates may be used in combination as the crosslinking agent. Polyfunctional metal chelates are those in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, and Ti. Examples of atoms in the organic compound that form covalent or coordinate bonds include oxygen atoms, and examples of organic compounds include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds.

[0118] The adhesive layer described above may contain other components besides those listed above, as long as they do not impair the effects of the present invention. Examples of these other components include curing agents, crosslinking catalysts, tackifying resins, anti-aging agents, fillers (metal powders, organic fillers, inorganic fillers, etc.), antioxidants other than phenolic antioxidants, plasticizers, softeners, surfactants, antistatic agents, surface lubricants, leveling agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, granular materials, foil-like materials, and colorants (pigments, dyes, etc.). Each of these other components may be used individually or in combination of two or more. The ratio of phenolic antioxidants to 100% by mass of the total amount of antioxidants in the adhesive layer is preferably 60% by mass or more, and may be 70% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more.

[0119] The adhesive layer may contain a crosslinking catalyst. Including a crosslinking catalyst can promote the crosslinking reaction by a crosslinking agent, etc. A tin-based catalyst (particularly dioctyl tin dilaurate) is preferred as the crosslinking catalyst. Only one type of crosslinking catalyst may be used, or two or more types may be used. The content of the crosslinking catalyst is, for example, 0.0001 to 1 part by mass per 100 parts by mass of polymer (A).

[0120] The above adhesive layer may contain a tackifying resin. When a tackifying resin is included, the adhesive layer tends to have better adhesion even when it is thin. Examples of the above tackifying resins include phenolic tackifying resins, terpene tackifying resins, rosin tackifying resins, hydrocarbon tackifying resins, epoxy tackifying resins, polyamide tackifying resins, elastomer tackifying resins, and ketone tackifying resins. Other examples of the above tackifying resins include low polymers of alkyl (meth)acrylates, such as low polymers of dicyclopentanyl methacrylate (DCPMA) and methyl methacrylate (MMA). Only one type of tackifying resin may be used, or two or more types may be used.

[0121] Examples of the above-mentioned phenolic tackifying resins include terpene phenol resins, hydrogenated terpene phenol resins, alkylphenol resins, and rosin phenol resins. The above-mentioned terpene phenol resins are polymers containing terpene residues and phenol residues, and include copolymers of terpenes and phenol compounds (terpene-phenol copolymer resins), and phenol-modified homopolymers or copolymers of terpenes (phenol-modified terpene resins). Examples of terpenes constituting the above-mentioned terpene phenol resins include monoterpenes such as α-pinene, β-pinene, and limonene (d-isomer, l-isomer, d / l-isomer (dipentene) etc.). The above-mentioned hydrogenated terpene phenol resins are resins having a structure obtained by hydrogenating the above-mentioned terpene phenol resins. The above-mentioned alkylphenol resins are resins obtained from alkylphenols and formaldehyde (oily phenol resins). Examples of the above-mentioned alkylphenol resins include novolac type and resol type. The above-mentioned rosin phenol resins are phenol-modified products of rosins or various rosin derivatives described later. The above-mentioned rosin-phenol resin can be obtained, for example, by adding phenol to rosins or various rosin derivatives described later using an acid catalyst and then thermally polymerizing them.

[0122] Examples of the above-mentioned terpene-based tackifying resins include polymers of terpenes (typically monoterpenes) such as α-pinene, β-pinene, d-limonene, l-limonene, and dipentene. The above-mentioned polymer of terpenes may be a single polymer of one terpene or a copolymer of two or more terpenes. Examples of single-polymer terpenes include α-pinene polymers, β-pinene polymers, and dipentene polymers. The above-mentioned modified terpene-based tackifying resin is a modified version of the above-mentioned terpene resin (modified terpene resin). Examples of the above-mentioned modified terpene resin include styrene-modified terpene resins and hydrogenated terpene resins.

[0123] Examples of the above-mentioned rosin-based tackifying resins include rosins and rosin derivative resins. Examples of the above-mentioned 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 hydrogenating, disproportionating, polymerization, etc., of these unmodified rosins. Examples of the above-mentioned rosin derivative resins include derivatives of the above-mentioned rosins. Examples of the above-mentioned rosin derivative resins include rosin esters such as unmodified rosin esters, which are esters of unmodified rosin and alcohols, and modified rosin esters, which are 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 the above-mentioned various rosin derivatives; and metal salts of rosins or the above-mentioned various rosin derivatives. Specific examples of the above-mentioned rosin esters include methyl esters of unmodified or modified rosin, triethylene glycol esters, glycerol esters, and pentaerythritol esters.

[0124] Examples of the hydrocarbon-based tackifying resins mentioned above 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.

[0125] The adhesive layer may be in any form, such as emulsion type, solvent type (solution type), active energy ray curing type, or hot melt type. Among these, solvent type and active energy ray curing type adhesive compositions are preferred because they make it easier to obtain an adhesive layer with excellent productivity.

[0126] The thickness of the adhesive layer (total thickness of the adhesive layer on one side) is not particularly limited, but is preferably 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 8 μm or more. The thickness is preferably 30 μm or less, and preferably 15 μm or less. If the thickness is 30 μm or less, the total outgassing amount of the adhesive sheet can be reduced. If the adhesive sheet is a double-sided adhesive sheet, the thickness of the adhesive layers on both sides may be the same or different.

[0127] The adhesive layer may be in any form, such as emulsion type, solvent type (solution type), active energy ray curing type, or hot melt type. Among these, solvent type and active energy ray curing type adhesive compositions are preferred because they make it easier to obtain an adhesive layer with excellent productivity.

[0128] Examples of the active energy rays mentioned above include ionizing radiation such as alpha rays, beta rays, gamma rays, neutron rays, and electron beams, as well as ultraviolet rays, with ultraviolet rays being particularly preferred. In other words, the active energy ray-curable adhesive layer is preferably an ultraviolet-curable adhesive layer.

[0129] The above-mentioned adhesive layer can be manufactured, for example, by applying an adhesive composition for forming the adhesive layer to a substrate or release liner, and then drying and curing the resulting adhesive composition layer, or by applying the adhesive composition to a substrate and curing the resulting adhesive composition layer by irradiating it with active energy rays. Furthermore, if necessary, it may be further heated and dried. The above-mentioned adhesive composition preferably contains a polymer (A), a polymer (B), and a phenolic antioxidant.

[0130] (Adhesive sheet) The thickness of the adhesive sheet is preferably 10 to 350 μm, more preferably 13 to 100 μm, and even more preferably 15 to 60 μm or more. A thickness of 10 μm or more provides excellent handling. A thickness of 350 μm or less allows for a thinner adhesive sheet. Note that the thickness of the adhesive sheet refers to the thickness from one adhesive surface to the other, i.e., the thickness of the adhesive material, and does not include the release liner.

[0131] The total outgassing amount of the above adhesive sheet is preferably 15,500 ppm or less, more preferably 13,000 ppm or less, even more preferably 10,000 ppm or less, and particularly preferably 3,000 ppm or less. The lower the total outgassing amount, the better from an environmental protection viewpoint. The total outgassing amount is 5 cm 2 The size of the adhesive sheet can be heated in a headspace sampler at 200°C for 60 minutes, and 1 mL of the gas phase portion after heating can be injected into a gas chromatograph for measurement. More specifically, the measurement can be performed under the conditions described in the examples.

[0132] The surface resistance value of the above adhesive sheet on the metal substrate surface is 10 -1 Ω / cm 2 The following are preferred, and more preferably 10 -2 Ω / cm 2 More preferably 10 -3 Ω / cm 2 The following are particularly preferred: -4 Ω / cm2 The following applies: The above surface resistance value can be measured using a URS probe under the conditions of 23°C, 50% RH atmosphere, JIS K6911, with an applied voltage of 10V and an applied time of 10 seconds.

[0133] The adhesive strength (initial adhesive strength) when the above adhesive sheet is attached to a SUS304BA plate and left for 30 minutes in a 23°C environment is preferably 4N / 25mm or less, more preferably 2N / 25mm or less, even more preferably 0.5N / 25mm or less, and particularly preferably 0.3N / 25mm or less. When the above initial adhesive strength is 4N / 25mm or less, the reworkability is excellent. From the viewpoint of preventing peeling off when attached to the substrate, the above initial adhesive strength is preferably 0.05N / 25mm or more.

[0134] The adhesive strength (adhesive strength after heating) when the above adhesive sheet is attached to a SUS304BA plate and left for 5 minutes in an 80°C environment is preferably 10N / 25mm or more, more preferably 15N / 25mm or more, even more preferably 18N / 25mm or more, and particularly preferably 20N / 25mm or more.

[0135] The above adhesive sheet may have a release liner attached to the surface (adhesive side) of the adhesive layer until use. If the above adhesive sheet is a double-sided adhesive sheet, each adhesive surface on both sides of the adhesive sheet may be protected by two release liners, or it may be protected in the form of a roll wound up by a single release liner with both sides being release surfaces. The release liner is used as a protective material for the adhesive layer and is peeled off when it is attached to the object. Note that the release liner is not necessarily required.

[0136] The above-mentioned release liner can be conventional release paper or the like, and is not particularly limited, but examples include a substrate having a release treatment layer, a low-adhesion substrate made of a fluoropolymer, or a low-adhesion substrate made of a nonpolar polymer. Examples of the substrate having the release treatment layer include plastic films and paper surface-treated with release agents such as silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide. Examples of fluorine-based polymers in the low-adhesion substrate made of a fluoropolymer include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, and chlorofluoroethylene-vinylidene fluoride copolymer. Examples of the above-mentioned nonpolar polymer include olefin resins (e.g., polyethylene, polypropylene, etc.). The release liner can be formed by known or conventional methods. The thickness of the release liner is also not particularly limited.

[0137] The above-mentioned adhesive sheet can be used for known or conventional applications of bonding adherends. In particular, the adhesive sheet is preferably used for insulating layer bonding applications in which the adhesive layer is bonded to an insulating layer. Furthermore, from the viewpoint of low total outgassing and excellent conductivity, the adhesive sheet is preferably used for battery component bonding applications, and more preferably for all-solid-state battery component bonding applications. Specific examples of battery component bonding applications include, for example, fixing circuit components in batteries and electrode applications in which the metal substrate acts as an electrode.

[0138] One embodiment of the above-mentioned applications for fixing circuit components and electrodes is, for example, the adhesive layer being used by laminating it to an insulating substrate such as a polyimide film, with the metal substrate acting as an electrode. The electrode may be a positive electrode or a negative electrode. An active material may also be attached to the metal substrate. For example, as shown in Figure 2, the adhesive sheet 1 is laminated to an insulating substrate 4 (Figure 2(a)), a series of cuts L are formed to cut the adhesive layer 3 and the metal substrate 2, forming a pattern 21 consisting of an adhesive pattern and a metal pattern that are identical in shape when projected in the thickness direction (Figure 2(b)), and the laminate 22 of the adhesive layer and metal substrate other than the pattern 21 may be peeled off from the insulating substrate 4 (Figure 2(c)). Furthermore, since the adhesive strength of the adhesive layer is improved by heating, the adhesive pattern can then be heated to improve the adhesive strength of the adhesive pattern to the insulating substrate. [Examples]

[0139] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by these examples.

[0140] Example 1 (Preparation of Polymer A1) In a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser, 60 parts by mass of 2-ethylhexyl acrylate (2EHA), 15 parts by mass of N-vinyl-2-pyrrolidone (NVP), 10 parts by mass of methyl methacrylate (MMA), 15 parts by mass of 2-hydroxyethyl acrylate (HEA), and 200 parts by mass of ethyl acetate as a polymerization solvent were charged. The mixture was stirred at 60°C under a nitrogen atmosphere for 2 hours, and then 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added as a thermal polymerization initiator. The reaction was carried out at 60°C for 6 hours to obtain a solution of polymer A1. The Mw of polymer A1 was 1.1 million, and the Tg according to Fox's formula was -36°C.

[0141] (Preparation of polymer B1) 100 parts by mass of toluene, 40 parts by mass of methyl methacrylate (MMA), 20 parts by mass of butyl methacrylate (BMA), 20 parts by mass of 2-ethylhexyl methacrylate (2-EHMA), 8.7 parts by mass of a methacrylate monomer containing a polyorganosiloxane skeleton with a functional group equivalent of 900 g / mol (trade name "X-22-174ASX", manufactured by Shin-Etsu Chemical Co., Ltd.), 11.3 parts by mass of a methacrylate monomer containing a polyorganosiloxane skeleton with a functional group equivalent of 4600 g / mol (trade name "KF-2012", manufactured by Shin-Etsu Chemical Co., Ltd.), and 0.51 parts by mass of methyl thioglycolate as a chain transfer agent were charged into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, a condenser, and a dropping funnel. Then, after stirring for 1 hour at 70°C under a nitrogen atmosphere, 0.2 parts by mass of AIBN as a thermal polymerization initiator was added, and after reacting at 70°C for 2 hours, 0.1 parts by mass of AIBN as a thermal polymerization initiator was added, and subsequently reacted at 80°C for 5 hours to obtain a solution of polymer B1. The Mw of the obtained polymer B1 was 20,000. Also, the functional group equivalent (arithmetic mean) of the polyorganosiloxane skeleton methacrylate monomer was 2990 g / mol.

[0142] The Mw of polymer A1 and polymer B1 was measured and calculated using a GPC device "HLC-8220GPC" (manufactured by Tosoh Corporation). The GPC conditions are as follows. <GPC Conditions> Sample concentration: 0.2 wt% (tetrahydrofuran (THF) solution) Sample injection volume: 10 μl Eluent: THF Flow rate: 0.6 ml / min Measurement temperature: 40°C Column: Sample column; TSKguardcolumn SuperHZ-H (1 piece) + TSKgel SuperHZM-H (2 pieces) Reference column; TSKgel SuperH-RC (1 piece) Detector: Differential refractometer (RI)

[0143] (Preparation of Adhesive Sheet) To the solution of polymer A1 described above, 2.5 parts by mass of polymer B1, 2.5 parts by mass of isocyanate-based crosslinking agent (trade name "Takenate D-110N", trimethylolpropane xylylene diisocyanate, manufactured by Mitsui Chemicals, Inc.), and 1.0 part by mass of phenol-based antioxidant (trade name "Irganox 1010", manufactured by BASF Japan Ltd.) were added per 100 parts by mass of polymer A1 and mixed uniformly to prepare an adhesive composition. The above adhesive composition was directly applied to an 18 μm thick electrolytic copper foil (product name "CF-T8G-UN-18", manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd.) as a base material, and dried by heating at 100°C for 2 minutes to form an adhesive layer with a thickness of 9 μm. The release layer surface of a release liner (product name "MRF38", manufactured by Mitsubishi Chemical Corporation, a release liner having a release layer on one side of a polyester film treated with a silicone-based release agent, with a thickness of 38 μm) was bonded to the surface (adhesive side) of this adhesive layer. In this way, an adhesive sheet with a release liner was obtained.

[0144] Examples 2-3 In preparing the adhesive composition, an adhesive sheet was prepared in the same manner as in Example 1, except that the amount of phenolic antioxidant was changed as shown in Table 1.

[0145] Example 4 An adhesive sheet was prepared in the same manner as in Example 2, except that a phenolic antioxidant (product name "Irganox 565") was used instead of a phenolic antioxidant (product name "Irganox 1010") in the preparation of the adhesive composition.

[0146] Example 5 An adhesive sheet was prepared in the same manner as in Example 2, except that aluminum foil (soft aluminum foil, conforming to JIS H4160A1N30H-0, manufactured by UACJ Corporation, 50 μm thick) was used instead of electrolytic copper foil.

[0147] Example 6 An adhesive sheet was prepared in the same manner as in Example 2, except that SUS foil (product name "SUS304 CSP-H", manufactured by Toyo Seihaku Co., Ltd., 40 μm thick) was used instead of electrolytic copper foil.

[0148] Comparative Examples 1-3 In preparing the adhesive composition, an adhesive sheet was prepared in the same manner as in Example 1, except that the amount of phenolic antioxidant was changed as shown in Table 2.

[0149] Comparative Example 4 In preparing the adhesive composition, an adhesive sheet was prepared in the same manner as in Example 1, except that a phenolic antioxidant was not included.

[0150] Comparative Example 5 An adhesive sheet was prepared in the same manner as in Example 2, except that a phosphorus-based antioxidant (product name "Irgafos168") was used instead of a phenol-based antioxidant (product name "Irganox1010") in the preparation of the adhesive composition.

[0151] Comparative Example 6 An adhesive sheet was prepared in the same manner as in Example 2, except that a PET film (product name "Toray Polyester Film "Lumirror (registered trademark)" #25 S10," manufactured by Toray Industries, Inc., 25 μm thick) was used instead of electrolytic copper foil.

[0152] <Rating> The adhesive sheets obtained in the examples and comparative examples were evaluated as follows. The results are shown in the table.

[0153] (1) Total outgassing 5cm of adhesive sheet 2 The sample was cut out, the release liner was peeled off, and the test specimen was collected and sealed in a headspace vial. Then, it was heated in a headspace sampler (HSS) at 200°C for 60 minutes, and 1 mL of the gas phase portion after heating was injected into a gas chromatograph (GC). The total amount of outgassing detected was then calculated. The analytical instruments and measurement conditions used are as follows. <Analyzer> HSS:Agilent Technologies,G1888 GC: Agilent Technologies, 6890N <Measurement conditions> (HSS condition) Heating temperature: 200℃ Heating time: 60min Sample loop temperature: 160℃ Transfer line temperature: 200℃ Pressurization time: 0.20 min Loop filling time: 0.20 min Loop equilibrium time: 0.05 min Injection time: 0.50min (GC conditions) Column: HP-1 (0.250 mmφ × 30 m, df = 1.0 μm) Column temperature: 40°C (3 min) → 10°C / min → 120°C → 20°C / min → 300°C (10 min) Column flow rate: 1 mL / min (He) Column pressure: Constant flow mode (81kPa) Inlet temperature: 250℃ Injection volume: 1mL Injection method: Split (20:1) Detector: FID Detector temperature: 250℃

[0154] (2) 180° peel-off adhesion test Test specimens were made by cutting the adhesive sheet into 25mm wide strips. A SUS plate (304BA plate) that had been cleaned with toluene was prepared. The release liner of the adhesive sheet was peeled off, and the adhesive side of the adhesive sheet was adhered to the SUS plate by moving a 2kg roller back and forth. For each example and comparative example, adhesive sheets were prepared under the following two conditions: (i) After adhering the adhesive sheet to the SUS plate, it was left at 23°C for 30 minutes (initial condition). (ii) After adhering the adhesive sheet to the SUS plate, it was left at 80°C for 5 minutes, and then left at 23°C for 30 minutes (post-80°C heating condition). For the adhesive sheets prepared under conditions (i) and (ii), the other end of the adhesive sheet was peeled off at a speed of 300mm / min in the peeling direction at a 180° angle, and the adhesive force (resistance) to the SUS plate at that time (unit: N / 25mm) was measured.

[0155] (3) Surface resistance The initial surface resistance [Ω / cm²] of the adhesive sheet substrate surface was measured using a URS probe under the conditions of JIS K6911, with a temperature of 23°C, a 50% RH atmosphere, an applied voltage of 10V, and an application time of 10 seconds. 2 The following was measured: The resistivity meter used was the "HighResta UP MCP-HT450" model (manufactured by Mitsubishi Chemical Corporation).

[0156] [Table 1]

[0157] [Table 2]

[0158] As shown in the table, the adhesive sheets of the examples were judged to have excellent reworkability and increased adhesive strength over time, due to their low initial adhesive strength and high adhesive strength after heating. Furthermore, they exhibited low surface resistance and excellent conductivity. Although Examples 2, 5, and 6 used the same adhesive layer, it is presumed that differences in the stiffness of the metal substrate, due to variations in the type and thickness of the metal substrate, resulted in differences in peel-off adhesive strength. The total outgassing amount of the adhesive sheets in the examples was reduced compared to cases with low phenolic antioxidant content (Comparative Examples 1-3), cases without phenolic antioxidant (Comparative Example 4), and cases using phosphorus-based antioxidant (Comparative Example 5). Additionally, when a plastic film was used as the substrate (Comparative Example 6), the surface resistance was low and conductivity was poor.

[0159] The following describes variations of the invention relating to this disclosure. [Note 1] The metal substrate and the adhesive layer provided on at least one surface of the metal substrate are provided. The adhesive layer comprises 100 parts by mass of polymer (A) having a glass transition temperature of less than 0°C, 0.1 to 20 parts by mass of polymer (B) having a polyorganosiloxane skeleton as monomer units (B1) and monomer (B2) having a homopolymer glass transition temperature of 40°C or higher, wherein the functional group equivalent (arithmetic mean) of monomer (B1) is 1000 g / mol or more and less than 15000 g / mol, and the weight-average molecular weight is 10000 or more and less than 100000, and 0.4 parts by mass or more of a phenolic antioxidant, and an adhesive sheet. [Note 2] The adhesive sheet according to Note 1, wherein the phenolic antioxidant is a compound containing two or more phenol skeletons. [Note 3] The adhesive sheet described in Note 1 or 2, wherein the total outgassing amount is 15,500 ppm or less. [Note 4] An adhesive sheet described in any one of Notes 1 to 3 for the purpose of attaching battery components. [Note 5] The adhesive sheet described in Note 4, which is for the purpose of attaching all-solid-state battery components. [Note 6] An electrode for an all-solid-state battery, comprising an insulating substrate, an adhesive sheet as described in Note 5 in which the adhesive layer is bonded to the insulating substrate, and an active material attached to a metal substrate in the adhesive sheet. [Explanation of Symbols]

[0160] 1 Adhesive sheet 2 Metal base material 21 patterns 22 Laminate 3. Adhesive layer 4. Insulating substrate

Claims

1. The device comprises a metal substrate and an adhesive layer provided on at least one surface of the metal substrate. The adhesive layer comprises a polymer (A) having a glass transition temperature of less than 0°C, a polymer (B) having a weight-average molecular weight of 10,000 or more and less than 100,000, and a phenolic antioxidant. The polymer (B) is present in an amount of 0.1 to 20 parts by mass per 100 parts by mass of polymer (A), and the phenolic antioxidant is present in an amount of 0.4 parts by mass or more. The polymer (A) is an acrylic polymer, The polymer (B) is a (meth)acrylic polymer, The polymer (B) contains a polyorganosiloxane skeleton methacrylate monomer (B1) and an acrylic monomer (B2) having a glass transition temperature of 40°C or higher as monomer units. The functional group equivalent (arithmetic mean) of the monomer (B1) is 1000 g / mol or more and less than 15000 g / mol. The sum of monomers (B1) and (B2) is 50% by mass or more of the total amount (100% by mass) of all monomer components constituting the polymer (B). The proportion of the monomer (B1) is 5% by mass or more and 60% by mass or less. An adhesive sheet in which the proportion of the monomer (B2) is 10% by mass or more and 80% by mass or less.

2. The adhesive sheet according to claim 1, wherein the phenolic antioxidant comprises a compound containing two or more phenol skeletons.

3. The adhesive sheet according to claim 1 or 2, wherein the total outgassing amount is 15,500 ppm or less.

4. The adhesive sheet according to claim 1 or 2, for use in attaching battery components.

5. The adhesive sheet according to claim 4, for use in attaching all-solid-state battery components.

6. An electrode for an all-solid-state battery, comprising an insulating substrate, an adhesive sheet according to claim 5 in which the adhesive layer is bonded to the insulating substrate, and an active material attached to a metal substrate in the adhesive sheet.

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