Adhesive composition, adhesive sheet, optical laminate, and image display device

Abstract

The present disclosure relates to the sufficient suppression of electrostatic charging of an adhesive layer, and to the suppression of corrosion of a metal layer when the adhesive layer is laminated onto the metal layer. The adhesive composition contains a (meth)acrylic resin and an ionic compound. The (meth)acrylic resin is a copolymer that contains a monomer unit derived from an alkoxyalkyl (meth)acrylate at a percentage of 1 mass% to 40 mass% with respect to the total amount of monomer units constituting the (meth)acrylic resin. The ionic compound has an anion having a pentafluorophenyl group and a cation.

Description

Pressure-sensitive adhesive composition, pressure-sensitive adhesive sheet, optical laminate, and image display device

[0001] The present disclosure relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet, an optical laminate, and an image display device.

[0002] In image display devices such as liquid crystal display devices and organic EL display devices, an optical laminate including an optical film such as a polarizing plate may be attached to another member via a pressure-sensitive adhesive layer (e.g., Patent Documents 1 to 4). This pressure-sensitive adhesive layer is generally distributed with a release film attached to one or both sides. The pressure-sensitive adhesive layer exposed by peeling off the release film is then attached to another member of the image display device. The pressure-sensitive adhesive layer may become charged when the release film is peeled off, which may cause damage to the image display device.

[0003] JP 2011-037927 A JP 2013-224431 A JP 2016-194694 A JP 2009-209257 A

[0004] The addition of an ionic compound to the adhesive layer can suppress the charging of the adhesive layer. However, conventional adhesive layers with suppressed charging tend to easily corrode metals that come into contact with the adhesive layer. In image display devices, the adhesive layer may come into contact with components that include a metal layer, such as metal wiring, so it is desirable to suppress metal corrosion caused by the adhesive layer. In particular, thin metal layers or metal wiring with a small width are prone to holes due to corrosion, so it is often particularly necessary to suppress metal corrosion.

[0005] The present disclosure relates to sufficiently suppressing static buildup in a pressure-sensitive adhesive layer and suppressing corrosion of a metal layer when the pressure-sensitive adhesive layer is attached to the metal layer.

[0006] The present disclosure includes the following: [1] A pressure-sensitive adhesive composition containing a (meth)acrylic resin and an ionic compound, wherein the (meth)acrylic resin is a copolymer containing monomer units derived from an alkoxyalkyl (meth)acrylate in a proportion of 1% by mass to 40% by mass, based on the total amount of monomer units constituting the (meth)acrylic resin, and the ionic compound has an anion having a pentafluorophenyl group and a cation. [2] The pressure-sensitive adhesive composition according to [1], wherein the (meth)acrylic resin contains monomer units derived from an alkyl (meth)acrylate having an alkyl group having 1 to 3 carbon atoms in a proportion of 5% by mass to 50% by mass, based on the total amount of monomer units constituting the (meth)acrylic resin. [3] The pressure-sensitive adhesive composition according to [1], wherein the (meth)acrylic resin contains monomer units derived from a monomer that forms a homopolymer having a glass transition temperature of 0°C or higher in a proportion of 5% by mass to 50% by mass, based on the total amount of monomer units constituting the (meth)acrylic resin. [4] The pressure-sensitive adhesive composition according to any one of [1] to [3], wherein the (meth)acrylic resin contains monomer units derived from a monomer having a carboxy group or an acid anhydride group in a proportion of 0.6% by mass to 10% by mass, based on the total amount of monomer units constituting the (meth)acrylic resin. [5] The pressure-sensitive adhesive composition according to any one of [1] to [4], wherein the content of the ionic compound is 0.1 parts by mass to 10 parts by mass, based on 100 parts by mass of the (meth)acrylic resin. [6] The pressure-sensitive adhesive composition according to any one of [1] to [5], wherein the ionic compound has a melting point of 23°C or higher. [7] The pressure-sensitive adhesive composition according to any one of [1] to [6], wherein the anion of the ionic compound contains a boron atom. [8] The pressure-sensitive adhesive composition according to any one of [1] to [8], wherein the cation of the ionic compound is an organic cation. [9] A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition according to any one of [1] to [8].

[10] The pressure-sensitive adhesive sheet according to [9], wherein the thickness of the pressure-sensitive adhesive layer is 2 μm or more and 50 μm or less.

[11] An optical laminate comprising a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition according to any one of [1] to [8], and an optical film attached to the pressure-sensitive adhesive layer.

[12] The optical laminate according to

[11] , wherein the optical film is a polarizing plate.

[13] The optical laminate according to

[12] , wherein the polarizing plate includes a retarder.

[14] An image display device comprising the optical laminate according to any one of

[11] to

[13] , and a metal layer in contact with the pressure-sensitive adhesive layer of the optical laminate.

[0007] This can sufficiently suppress the static buildup of the pressure-sensitive adhesive layer, and can also suppress corrosion of the metal layer when the pressure-sensitive adhesive layer is attached to the metal layer.

[0008] 1 is a schematic cross-sectional view showing an example of a pressure-sensitive adhesive sheet; 2 is a schematic cross-sectional view showing an example of an optical laminate; 3 is a schematic cross-sectional view showing an example of an image display device;

[0009] The present invention is not limited to the following examples: In this specification, "(meth)acrylic" means acrylic, methacrylic or both.

[0010] <Pressure-Sensitive Adhesive Composition> An example of a pressure-sensitive adhesive composition contains a (meth)acrylic resin and an ionic compound. The (meth)acrylic resin is a copolymer containing a monomer unit derived from an acrylic acid ester, a monomer unit derived from a methacrylic acid ester, or both. A pressure-sensitive adhesive layer formed by forming a film from the pressure-sensitive adhesive composition can be used to bond various members, such as optical films, to other adherends.

[0011] The (meth)acrylic resin may contain one or more monomer units derived from an alkoxyalkyl (meth)acrylate. The combination of a (meth)acrylic resin containing a monomer unit derived from an alkoxyalkyl (meth)acrylate with an ionic compound can further enhance the antistatic effect of the pressure-sensitive adhesive layer.

[0012] The monomer unit derived from an alkoxyalkyl (meth)acrylate is represented, for example, by the following formula (A1): １ represents a hydrogen atom or a methyl group, and R ２ represents an alkylene group having 1 to 4 carbon atoms, and R３ represents an alkyl group having 1 to 4 carbon atoms, and n represents an integer of 1 to 10.

[0013] Examples of the alkoxyalkyl (meth)acrylate from which the monomer unit represented by formula (A1) is derived include 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-methoxy-2-ethoxyethyl acrylate, 2-methoxyethyl methacrylate, 2-ethoxyethyl methacrylate, and 2-(2-methoxyethoxy)ethyl methacrylate. In particular, it is preferred that the (meth)acrylic resin contains a monomer unit derived from 2-methoxyethyl acrylate.

[0014] The proportion of the monomer units derived from the alkoxyalkyl (meth)acrylate may be 1% by mass or more and 40% by mass or less, based on the total amount of the monomer units constituting the (meth)acrylic resin. This proportion may be 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more, or may be 35% by mass or less. When the proportion of the monomer units derived from the alkoxyalkyl (meth)acrylate is within these ranges, particularly excellent effects can be obtained in terms of suppressing static charge in the pressure-sensitive adhesive layer and suppressing metal corrosion.

[0015] The (meth)acrylic resin may further contain one or more monomer units derived from an alkyl (meth)acrylate having an alkyl group having 1 to 3 carbon atoms. The monomer unit derived from an alkyl (meth)acrylate having an alkyl group having 1 to 3 carbon atoms is represented, for example, by the following formula (A2). In formula (A2), R １ represents a hydrogen atom or a methyl group, and R ４ represents an alkyl group having 1 to 3 carbon atoms (for example, a methyl group, an ethyl group, an n-propyl group, or an isopropyl group).

[0016] The proportion of monomer units derived from alkyl (meth)acrylate having an alkyl group with 1 to 3 carbon atoms may be 5% by mass or more and 50% by mass or less, based on the total amount of monomer units constituting the (meth)acrylic resin. This proportion may be 10% by mass or more, 40% by mass or less, or 30% by mass or less. When the proportion of monomer units derived from alkyl (meth)acrylate having an alkyl group with 1 to 3 carbon atoms is within these ranges, the durability of the pressure-sensitive adhesive layer may be further improved.

[0017] Examples of alkyl (meth)acrylates from which the monomer unit represented by formula (A2) is derived include methyl acrylate, ethyl acrylate, n-propyl acrylate, methyl methacrylate, ethyl methacrylate, and n-propyl methacrylate.

[0018] The (meth)acrylic resin may further contain one or more monomer units derived from a monomer having a carboxy group or an acid anhydride group. The monomer units derived from a monomer having a carboxy group or an acid anhydride group are represented, for example, by the following formula (A3-1), (A3-2), (A3-3), (A3-4), or (A3-5). In formulas (A3-1) and (A3-2), R １ represents a hydrogen atom or a methyl group. ５ represents an alkylene group. ５ may be an alkylene group having 1 to 6 carbon atoms (for example, a methylene group, an ethylene group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, or a hexane-1,6-diyl group). ６ represents an alkyl group having 1 to 3 carbon atoms (for example, a methyl group).

[0019] Examples of the monomer having a carboxy group or an acid anhydride group include (meth)acrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, carboxyalkyl (meth)acrylates (e.g., carboxyethyl (meth)acrylate, and carboxypentyl (meth)acrylate. The monomer having a carboxy group may be (meth)acrylic acid, β-carboxyethyl acrylate, or a combination thereof. In particular, it is preferable to use acrylic acid from the viewpoint of improving the durability of the PSA.

[0020] The proportion of monomer units derived from monomers having a carboxy group or an acid anhydride group may be 0.6% by mass or more and 10% by mass or less, based on the total amount of monomer units constituting the (meth)acrylic resin. This proportion may be 1% by mass or more, 5% by mass or less, or 3% by mass or less. When the proportion of monomer units derived from monomers having a carboxy group or an acid anhydride group is within these ranges, particularly excellent effects can be exhibited in terms of improving adhesive strength and durability, and suppressing metal corrosion.

[0021] The (meth)acrylic resin may further contain one or more monomer units derived from a (meth)acrylic acid ester having an alkyl group having 4 to 14 carbon atoms or an alkyl group having 1 to 14 carbon atoms substituted with an aryl group. This monomer unit is represented, for example, by the following formula (A4). In formula (A4), R １ represents a hydrogen atom or a methyl group, and R ７ represents an alkyl group having 4 to 14 carbon atoms, or an alkyl group having 1 to 14 carbon atoms substituted with an aryl group.

[0022] Examples of the monomer from which the monomer unit represented by formula (A4) is derived include n-butyl acrylate, n-octyl acrylate, lauryl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, n-butyl methacrylate, n-octyl methacrylate, lauryl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, isooctyl methacrylate, benzyl acrylate, and benzyl methacrylate.

[0023] The proportion of monomer units derived from a (meth)acrylic acid ester having an alkyl group having 4 to 14 carbon atoms or an alkyl group having 1 to 14 carbon atoms substituted with an aryl group may be 0% by mass or more and 84.4% by mass or less, based on the total amount of monomer units constituting the (meth)acrylic resin. This proportion may be 10% by mass or more, or 15% by mass or more, and may be 79.4% by mass or less, 74.4% by mass or less, or 69.4% by mass or less. Having the proportion of monomer units derived from a (meth)acrylic acid ester having an alkyl group having 4 to 14 carbon atoms or an alkyl group having 1 to 14 carbon atoms substituted with an aryl group within these ranges is advantageous in terms of appropriate tackiness and durability of the pressure-sensitive adhesive layer.

[0024] The (meth)acrylic resin may further contain one or more monomer units derived from a monomer having a polar functional group other than a carboxy group and an acid anhydride group. This monomer unit may have one or more polar functional groups selected from a hydroxyl group, an amino group, an amide group, and a cyclic ether group (e.g., an epoxy group, a tetrahydrofuryl group). The polar functional group is preferably a hydroxyl group, an amino group, or an epoxy group, and more preferably a hydroxyl group. The durability of the pressure-sensitive adhesive layer can be further improved by combining these monomer units having a polar functional group with a crosslinking agent described below.

[0025] The monomer having a polar functional group other than a carboxy group or an acid anhydride group may be a derivative of (meth)acrylic acid. Examples of monomers having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-chloro-2-hydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, diethylene glycol mono(meth)acrylate, and 2-hydroxybutyl (meth)acrylate. Examples of monomers having an amino group include acryloylmorpholine and N,N-dimethylaminoethyl (meth)acrylate. Examples of monomers having an amide group include vinyl caprolactam and N-vinyl-2-pyrrolidone. Examples of monomers having a cyclic ether group include tetrahydrofurfuryl (meth)acrylate, caprolactone-modified tetrahydrofurfuryl acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, glycidyl (meth)acrylate, and 2,5-dihydrofuran.

[0026] The proportion of monomer units derived from monomers having polar functional groups other than carboxy groups and acid anhydride groups may be 0.5% by mass or more and 10% by mass or less, based on the total amount of monomer units constituting the (meth)acrylic resin. This proportion may be 1.0% by mass or more, 5% by mass or less, or 3% by mass or less. When the proportion of monomer units derived from monomers having polar functional groups is within these ranges, the durability of the pressure-sensitive adhesive layer can be further improved while maintaining appropriate adhesiveness.

[0027] The (meth)acrylic resin may contain monomer units derived from a monomer that forms a homopolymer having a glass transition temperature (Tg) of 0°C or higher. The glass transition temperatures of homopolymers formed by homopolymerization of various monomers can be determined, for example, by referring to literature values. The monomer that forms a homopolymer having a glass transition temperature of 0°C or higher may be an alkyl (meth)acrylate having an alkyl group having 1 to 3 carbon atoms. Examples of monomers that form a homopolymer having a glass transition temperature of 0°C or higher include methyl acrylate (homopolymer Tg: 10°C), methyl methacrylate (homopolymer Tg: 105°C), ethyl methacrylate (homopolymer Tg: 65°C), butyl methacrylate (homopolymer Tg: 20°C), isobornyl acrylate (homopolymer Tg: 94°C), isobornyl methacrylate (homopolymer Tg: 110°C), t-butyl acrylate (homopolymer Tg: 107°C), and t-butyl methacrylate (homopolymer Tg: 118°C). The Tg of each homopolymer shown in parentheses is the value described in POLYMER HANDBOOK THIRD EDITION J. Brandrup E. H. Immergut. Some or all of the monomer units derived from a monomer forming a homopolymer having a glass transition temperature (Tg) of 0°C or higher, such as a monomer unit derived from an alkoxyalkyl (meth)acrylate, a monomer unit derived from an alkyl (meth)acrylate having an alkyl group of 1 to 3 carbon atoms, a monomer unit derived from a monomer having a carboxy group or an acid anhydride group, a (meth)acrylic acid ester having an alkyl group of 4 to 14 carbon atoms or an aryl group-substituted alkyl group of 1 to 14 carbon atoms, and a monomer unit derived from a monomer having a polar functional group other than a carboxy group or an acid anhydride group, may correspond to monomer units derived from a monomer forming a homopolymer having a glass transition temperature (Tg) of 0°C or higher.

[0028] The proportion of monomer units derived from monomers forming a homopolymer having a glass transition temperature (Tg) of 0°C or higher may be 5% by mass or more and 50% by mass or less, based on the total amount of monomer units constituting the (meth)acrylic resin. This proportion is preferably 10% by mass or more or 15% by mass or more, and more preferably 40% by mass or less or 30% by mass or less. When the proportion of monomer units derived from monomers forming a homopolymer having a glass transition temperature (Tg) of 0°C or higher is within these ranges, the durability of the pressure-sensitive adhesive layer can be further improved.

[0029] The (meth)acrylic resin may further contain one or more monomer units derived from other monomers having structures different from the monomers exemplified above. However, some or all of the other monomers exemplified here may correspond to monomer units derived from monomers that form homopolymers having a glass transition temperature (Tg) of 0° C. or higher. Examples of other monomers include (meth)acrylic acid esters having an alicyclic group, styrene-based monomers, vinyl-based monomers, and monomers having multiple (meth)acryloyl groups.

[0030] The alicyclic group of the monomer having an alicyclic group may be a cycloparaffin group having 5 or more carbon atoms, or about 5 to 7 carbon atoms. The monomer having an alicyclic group may be an acrylate ester, examples of which include cyclohexyl acrylate, dicyclopentanyl acrylate, cyclododecyl acrylate, methylcyclohexyl acrylate, trimethylcyclohexyl acrylate, tert-butylcyclohexyl acrylate, α-ethoxycyclohexyl acrylate, and cyclohexylphenyl acrylate. The monomer having an alicyclic group may be a methacrylate ester, examples of which include cyclohexyl methacrylate, dicyclopentanyl methacrylate, cyclododecyl methacrylate, methylcyclohexyl methacrylate, trimethylcyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, and cyclohexylphenyl methacrylate.

[0031] Examples of styrene-based monomers include styrene, alkylstyrenes (e.g., methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, octylstyrene), halogenated styrenes (e.g., fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, iodostyrene), nitrostyrene, acetylstyrene, methoxystyrene, and divinylbenzene.

[0032] Examples of vinyl monomers include fatty acid vinyl esters (e.g., vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate), vinyl halides (e.g., vinyl chloride, vinyl bromide), vinylidene halides (e.g., vinylidene chloride), nitrogen-containing aromatic vinyl compounds (e.g., vinylpyridine, vinylpyrrolidone, vinylcarbazole), conjugated dienes (e.g., butadiene, isoprene, chloroprene), acrylonitrile, and methacrylonitrile.

[0033] Examples of the monomer having two (meth)acryloyl groups include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and tripropylene glycol di(meth)acrylate. An example of the monomer having three (meth)acryloyl groups includes trimethylolpropane tri(meth)acrylate.

[0034] The proportion of the monomer units derived from other monomers may be 0% by mass or more and 20% by mass or less, or 0% by mass or more and 10% by mass or less, based on the total amount of the monomer units constituting the (meth)acrylic resin.

[0035] The pressure-sensitive adhesive composition may contain one type of (meth)acrylic resin, or may contain two or more types of (meth)acrylic resins that differ in the type of monomer and / or the copolymerization ratio of the monomer.

[0036] The weight-average molecular weight (Mw) of the (meth)acrylic resin may be 1,000,000 or more and 2,000,000 or less. When the weight-average molecular weight of the (meth)acrylic resin is 1,000,000 or more, the adhesiveness of the pressure-sensitive adhesive layer under high temperature and high humidity conditions is improved, and therefore, lifting or peeling tends to be less likely to occur between the pressure-sensitive adhesive layer and, for example, a metal layer or a glass substrate. When the weight-average molecular weight of the (meth)acrylic resin is 2,000,000 or less, the pressure-sensitive adhesive composition is likely to have an appropriate viscosity, thereby suppressing streaks and unevenness in the pressure-sensitive adhesive layer. In this specification, the weight-average molecular weight refers to the weight-average molecular weight (Mw) calculated in terms of standard polystyrene by gel permeation chromatography (GPC).

[0037] The glass transition temperature of the (meth)acrylic resin may be −10° C. or higher and −60° C. or lower, −20° C. or higher and −50° C. or lower, or −30° C. or higher and −45° C. or lower. The glass transition temperature here may be a value determined by differential scanning calorimetry.

[0038] The (meth)acrylic resin may be a combination of two types of (meth)acrylic resins having different weight-average molecular weights, for example, a (meth)acrylic resin having a weight-average molecular weight of 1,000,000 or more and 2,000,000 or less and a (meth)acrylic resin having a weight-average molecular weight of 50,000 or more and 300,000 or less may be combined.

[0039] The viscosity of a solution having a solids concentration of 20% by mass, formed by dissolving the (meth)acrylic resin in ethyl acetate, at 25°C may be 20 Pa·s or less. If this viscosity is 20 Pa·s or less, the occurrence of streaks in the pressure-sensitive adhesive layer can be suppressed. From the same viewpoint, the viscosity of the solution at 25°C may be 0.1 Pa·s or more and 15 Pa·s or less. The viscosity may be a value measured using a Brookfield viscometer.

[0040] The (meth)acrylic resin can be produced by a conventional method such as solution polymerization, emulsion polymerization, bulk polymerization, or suspension polymerization. A polymerization initiator is usually used in the production of the (meth)acrylic resin (A-1). The amount of the polymerization initiator may be about 0.001 to 5 parts by mass relative to 100 parts by mass of the total amount of all monomers used in the production of the (meth)acrylic resin.

[0041] The pressure-sensitive adhesive composition contains one or more ionic compounds. At least a portion of the one or more ionic compounds is a compound formed from an anion having a pentafluorophenyl group represented by the following formula and a cation (counter cation). The ionic compound having an anion having a pentafluorophenyl group can contribute to suppressing static buildup in the pressure-sensitive adhesive layer and inhibiting corrosion of the metal layer.

[0042] The anion may contain a boron atom. Examples of anions containing a pentafluorophenyl group and a boron atom include tetrakispentafluorophenyl borate, represented by the following formula (B1):

[0043] The cation constituting the ionic compound may be an organic cation. Examples of the organic cation include a substituted ammonium cation, a pyrrolidinium cation, an imidazolium cation, a pyridinium cation, a sulfonium cation, and a phosphonium cation. A pressure-sensitive adhesive containing an ionic compound having a phosphonium cation is preferred because the heat resistance of the pressure-sensitive adhesive is improved due to the thermal stability of the phosphonium cation.

[0044] The total number of carbon atoms contained in the organic cation may be 8 or more and 48 or less. When the total number of carbon atoms contained in the organic cation is 8 or more, the polarity of the ionic compound is reduced, thereby improving the compatibility of the ionic compound with the PSA. When the total number of carbon atoms contained in the organic cation is 48 or less, the molecular weight of the ionic compound is small, so the amount of ionic compound required to achieve the desired antistatic properties can be reduced, thereby suppressing fluctuations in adhesive properties due to the ionic compound. From the same perspective, the total number of carbon atoms contained in the organic cation may be 12 or more and 36 or less, or 16 or more and 24 or less.

[0045] Examples of substituted ammonium cations include tributylmethylammonium cation, trioctylmethylammonium cation, trimethylpropylammonium cation, tetrabutylammonium cation, and (2-hydroxyethyl)trimethylammonium cation. Examples of pyrrolidinium cations include butylmethylpyrrolidinium cation and ethylmethylpyrrolidinium cation. Examples of phosphonium cations include tributyldodecylphosphonium cation. Examples of pyridinium cations include 1-hexylpyridinium cation, 1-octylpyridinium cation, 4-methyl-1-hexylpyridinium cation, 4-methyl-1-octylpyridinium cation, and 4-methyl-1-butylpyridinium cation. Examples of imidazolium cations include 1-ethyl-3-methylimidazolium cation and 1-butyl-3-methylimidazolium cation.

[0046] When the ionic compound is solid at room temperature, the antistatic performance tends to be easily maintained for a long period of time. From this viewpoint, the ionic compound preferably has a melting point of 23° C. or higher. The melting point of the ionic compound is more preferably 50° C. or higher, 75° C. or higher, or 100° C. or higher.

[0047] The molecular weight of the ionic compound is not particularly limited, but may be, for example, 500 or more, or 800 or more, and 1500 or less, or 1200 or less.

[0048] The ionic compound may be, for example, one or more selected from decylpyridinium tetrakispentafluorophenylborate, tributyldodecylphosphonium tetrakispentafluorophenylborate, and trioctylmethylammonium tetrakispentafluorophenylborate.

[0049] In the pressure-sensitive adhesive composition, the content of the ionic compound having an anion having a pentafluorophenyl group may be 0.1 parts by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic resin. The content of the ionic compound having an anion having a pentafluorophenyl group may be 5 parts by mass or less, 2.5 parts by mass or less, or 1.5 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic resin. Having the ionic compound content within these ranges is advantageous in terms of antistatic properties and suppressing bleed-out of the ionic compound.

[0050] The pressure-sensitive adhesive composition may contain two or more ionic compounds having different combinations of anion and cation. The pressure-sensitive adhesive composition may contain one or more ionic compounds having an anion having a pentafluorophenyl group and one or more ionic compounds having an anion without a pentafluorophenyl group. The content of the ionic compound having an anion without a pentafluorophenyl group in the pressure-sensitive adhesive composition may be 0 to 5.0 parts by mass, 0 to 4.0 parts by mass, 0 to 3.0 parts by mass, 0 to 2.0 parts by mass, 0 to 1.0 parts by mass, or 0 to 0.5 parts by mass, relative to 100 parts by mass of the (meth)acrylic resin.

[0051] The pressure-sensitive adhesive composition may further contain a crosslinking agent. The crosslinking agent is a compound having two or more functional groups capable of reacting with and bonding to the (meth)acrylic resin. The crosslinking agent may contain, for example, one or more compounds selected from a polyisocyanate compound, a polyepoxy compound, a metal chelate compound, and a polyaziridine compound.

[0052] The polyisocyanate compound is a compound having two or more isocyanato groups (-NCO), and examples thereof include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate. The crosslinking agent may include an adduct formed by reacting these polyisocyanate compounds with a polyol such as glycerol or trimethylolpropane, or may include a dimer or trimer of the polyisocyanate compound. Two or more polyisocyanate compounds may be used in combination.

[0053] The polyepoxy compound is a compound having two or more epoxy groups, and examples thereof include bisphenol A type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, N,N-diglycidylaniline, N,N,N',N'-tetraglycidyl-m-xylylenediamine, and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane. Two or more polyepoxy compounds may be used in combination.

[0054] A metal chelate compound is a compound composed of a polyvalent metal and an organic ligand that forms a coordinate bond with the polyvalent metal. Examples of polyvalent metals include aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. Examples of organic ligands include acetylacetone and ethyl acetoacetate.

[0055] A polyaziridine compound is a compound having two or more three-membered cyclic groups (aziridine groups) each consisting of one nitrogen atom and two carbon atoms. Examples of the polyaziridine compound include diphenylmethane-4,4'-bis(1-aziridinecarboxamide), toluene-2,4-bis(1-aziridinecarboxamide), triethylenemelamine, isophthaloylbis-1-(2-methylaziridine), tris-1-aziridinylphosphine oxide, hexamethylene-1,6-bis(1-aziridinecarboxamide), trimethylolpropane-tri-β-aziridinylpropionate, and tetramethylolmethane-tri-β-aziridinylpropionate.

[0056] Among these crosslinking agents, polyisocyanate compounds are preferably used from the viewpoint of improving durability. In particular, when the (meth)acrylic resin has a polar functional group selected from a carboxy group, a hydroxyl group, and an amino group, it is preferable that the crosslinking agent contains a polyisocyanate compound from the viewpoint of forming a crosslinked structure and improving durability. Among these, the crosslinking agent preferably contains xylylene diisocyanate, tolylene diisocyanate, or hexamethylene diisocyanate, an adduct formed from these polyisocyanate compounds and a polyol, or a dimer or trimer of these polyisocyanate compounds, and more preferably contains one or more selected from tolylene diisocyanate, an adduct formed from tolylene diisocyanate and a polyol, a dimer of tolylene diisocyanate, and a trimer of tolylene diisocyanate.

[0057] The content of the crosslinking agent may be 0.01 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the (meth)acrylic resin. The content of the crosslinking agent may be 0.1 parts by mass or more, or may be 5 parts by mass or less, 3 parts by mass or less, or 1 part by mass or less per 100 parts by mass of the (meth)acrylic resin. When the content of the crosslinking agent is within these ranges, a pressure-sensitive adhesive layer having excellent durability and high mechanical strength is easily formed.

[0058] The pressure-sensitive adhesive composition preferably further contains a silane compound. The silane compound can contribute to further improving the adhesion of the pressure-sensitive adhesive layer. Examples of silane compounds include low-molecular-weight silane compounds and silicone oligomers. From the viewpoint of adhesion to metals and glass, it is preferable to use low-molecular-weight silane compounds. Two or more silane compounds may be combined in the pressure-sensitive adhesive composition.

[0059] The low molecular weight silane compound may be a compound having a group selected from a vinyl group, an amino group, an epoxy group, a chloro group, a (meth)acryloyl group, and a mercapto group. Examples of low molecular weight silane compounds having a vinyl group include vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris(2-methoxyethoxy)silane. Examples of low molecular weight silane compounds having an amino group include N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and 3-aminopropyltriethoxysilane. Examples of low molecular weight silane compounds having an epoxy group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, and 3-glycidoxypropylethoxydimethylsilane. Examples of low molecular weight silane compounds having a chloro group include 3-chloropropylmethyldimethoxysilane and 3-chloropropyltrimethoxysilane. An example of a low molecular weight silane compound having a (meth)acryloyl group includes 3-methacryloyloxypropyltrimethoxysilane. An example of a low molecular weight silane compound having a mercapto group includes 3-mercaptopropyltrimethoxysilane. In particular, when the (meth)acrylic resin has a carboxyl group, an acid anhydride group, or other polar functional group, from the viewpoint of reactivity with these functional groups, the low molecular weight silane compound preferably contains a group selected from an epoxy group, an amino group, and a mercapto group, and particularly preferably contains an epoxy group.

[0060] The silicone oligomer may be a copolymer having an epoxy group, a mercaptopropyl group, a mercaptomethyl group, a methacryloyloxypropyl group, an acryloyloxypropyl group, a vinyl group, or an amino group. In particular, from the viewpoint of reactivity with the carboxyl group, acid anhydride group, and polar functional group in the acrylic polymer, the silicone oligomer preferably contains a group selected from the group consisting of an epoxy group, an amino group, a mercaptopropyl group, and a mercaptomethyl group, and more preferably contains an epoxy group.

[0061] Examples of silicone oligomers that are copolymers having epoxy groups include 3-glycidoxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-glycidoxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-glycidoxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-glycidoxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-glycidoxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-glycidoxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-glycidoxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-glycidoxypropylmethyldiethoxysilane-tetraethoxysilane copolymer.

[0062] Examples of silicone oligomers that are copolymers having mercaptopropyl groups include 3-mercaptopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-mercaptopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-mercaptopropyltriethoxysilane-tetramethoxysilane copolymer, and 3-mercaptopropyltriethoxysilane-tetraethoxysilane copolymer.

[0063] Examples of silicone oligomers that are copolymers having mercaptomethyl groups include mercaptomethyltrimethoxysilane-tetramethoxysilane copolymer, mercaptomethyltrimethoxysilane-tetraethoxysilane copolymer, mercaptomethyltriethoxysilane-tetramethoxysilane copolymer, and mercaptomethyltriethoxysilane-tetraethoxysilane copolymer.

[0064] Examples of silicone oligomers that are copolymers having methacryloyloxypropyl groups include 3-methacryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-methacryloyloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer.

[0065] Examples of silicone oligomers that are copolymers having acryloyloxypropyl groups include 3-acryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-acryloyloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer.

[0066] Examples of silicone oligomers that are copolymers having vinyl groups include vinyltrimethoxysilane-tetramethoxysilane copolymer, vinyltrimethoxysilane-tetraethoxysilane copolymer, vinyltriethoxysilane-tetramethoxysilane copolymer, vinyltriethoxysilane-tetraethoxysilane copolymer, vinylmethyldimethoxysilane-tetramethoxysilane copolymer, vinylmethyldimethoxysilane-tetraethoxysilane copolymer, vinylmethyldiethoxysilane-tetramethoxysilane copolymer, and vinylmethyldiethoxysilane-tetraethoxysilane copolymer.

[0067] Examples of silicone oligomers that are copolymers having amino groups include 3-aminopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-aminopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-aminopropyltriethoxysilane-tetramethoxysilane copolymer, 3-aminopropyltriethoxysilane-tetraethoxysilane copolymer, 3-aminopropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-aminopropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-aminopropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-aminopropylmethyldiethoxysilane-tetraethoxysilane copolymer.

[0068] The molecular weight of the silane compound may be 1000 or less, 500 or less, or 250 or less, from the viewpoint of efficient coating of the adherend.

[0069] The content of the silane compound is usually about 0.01 to 10 parts by mass per 100 parts by mass of the (meth)acrylic resin. The content of the silane compound may be 0.03 parts by mass or more, or 0.1 parts by mass or more, and may be 5 parts by mass or less, or 1 part by mass or less, per 100 parts by mass of the (meth)acrylic resin. When the content of the silane compound is within these ranges, the adhesion of the pressure-sensitive adhesive layer to the adherend can be further improved while suppressing bleed-out of the silane compound.

[0070] The pressure-sensitive adhesive composition may further contain other components, such as an ultraviolet-curable compound, a crosslinking catalyst, a weather stabilizer, a tackifier, a plasticizer, a softener, a dye, a pigment, and an inorganic filler.

[0071] A pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing an ultraviolet-curable compound can be cured by irradiation with ultraviolet light, and a harder pressure-sensitive adhesive layer can be formed by curing.

[0072] The pressure-sensitive adhesive composition may contain a crosslinking agent and a crosslinking catalyst. Using a pressure-sensitive adhesive composition containing a crosslinking agent and a crosslinking catalyst allows a pressure-sensitive adhesive layer containing a crosslinked (meth)acrylic resin to be formed in a short time. As a result, lifting and peeling between the pressure-sensitive adhesive layer and the substrate in contact with the pressure-sensitive adhesive layer, as well as foaming within the pressure-sensitive adhesive layer, can be suppressed. The crosslinking catalyst may be an amine compound, examples of which include hexamethylenediamine, ethylenediamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethylenetetramine, isophoronediamine, trimethylenediamine, polyamino resins, and melamine resins. In particular, a combination of a polyisocyanate compound as a crosslinking agent and an amine compound as a crosslinking catalyst may be used.

[0073] The PSA composition may contain a solvent that dissolves or disperses each component. In this case, for example, a PSA sheet having a PSA layer containing the PSA composition can be formed by a method including removing the solvent from a film of the PSA composition containing the solvent. The solvent may be, for example, ethyl acetate or methyl ethyl ketone. The PSA layer formed by removing the solvent may be allowed to stand for aging. For example, the PSA layer is allowed to stand for 7 days or more in an environment of 23°C and a relative humidity of 60%.

[0074] <Adhesive Sheet> Fig. 1 is a cross-sectional view showing an example of a pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet 1 shown in Fig. 1 has a first release film 11, a pressure-sensitive adhesive layer 10, and a second release film 12. The first release film 11, the pressure-sensitive adhesive layer 10, and the second release film 12 are laminated in this order.

[0075] The pressure-sensitive adhesive layer 10 can be a layer containing the above-mentioned pressure-sensitive adhesive composition. In a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing a crosslinking agent, the (meth)acrylic resin may be crosslinked by a reaction with the crosslinking agent.

[0076] The thickness of the pressure-sensitive adhesive layer 10 may be, for example, 2 μm or more and 50 μm or less. The thickness of the pressure-sensitive adhesive layer 10 may be 5 μm or more, or 10 μm or more, or may be 30 μm or less, 25 μm or less, or 20 μm or less. When the thickness of the pressure-sensitive adhesive layer is within these ranges, the pressure-sensitive adhesive layer tends to have particularly excellent durability. Furthermore, when a laminate (optical laminate) having the pressure-sensitive adhesive layer is cut, the pressure-sensitive adhesive layer tends to be less likely to be damaged.

[0077] The first release film 11 and the second release film are films having a releasable surface. The first release film 11 and the second release film may be a resin film such as a polyethylene terephthalate film, a polybutylene terephthalate film, a polycarbonate film, or a polyarylate film. The releasable surface can be formed by a release treatment such as a silicone treatment. The thickness of the first release film 11 and the second release film is not particularly limited, but may be, for example, 5 μm or more and 100 μm or less.

[0078] <Optical Laminate> The optical laminate has an optical film and a pressure-sensitive adhesive layer provided on one or both surfaces of the optical film. The pressure-sensitive adhesive layer may be a layer containing the pressure-sensitive adhesive composition described above.

[0079] The optical film constituting the optical laminate is a film having some optical function. The optical film may be, for example, a linear polarizing layer, a retarder, a reflective film, a semi-transmissive reflective film, a brightness-enhancing film, an anti-glare film, or a laminate film containing a combination of two or more selected from these. An optical film having a linear polarizing layer may further have a protective layer provided on one or both sides of the linear polarizing layer. The optical film may be a film that functions as a linear polarizing plate or a circular polarizing plate. An optical film that functions as a circular polarizing plate is usually a laminate including a linear polarizing layer and a retarder. A surface protective film may be provided on one side of the film that functions as a linear polarizing plate or a circular polarizing plate. The optical film may be a retardation plate having a retarder and a protective layer provided on one or both sides of the retarder.

[0080] FIG. 2 is a cross-sectional view showing an example of an optical laminate. The optical laminate 2 shown in FIG. 2 is composed of an optical film 20, a pressure-sensitive adhesive layer 10 provided on one main surface of the optical film 20, and a first release film 11 provided on the side of the pressure-sensitive adhesive layer 10 opposite the optical film 20. The laminate of the pressure-sensitive adhesive layer 10 and the first release film 11 corresponds to the pressure-sensitive adhesive sheet 1 in FIG. 1 from which the second release film 12 has been peeled. However, the pressure-sensitive adhesive layer 10 may be formed by a method including applying a pressure-sensitive adhesive composition to an optical film without using the pressure-sensitive adhesive sheet 1, and then the first release film 11 may be laminated on the pressure-sensitive adhesive layer 10. The optical film 20 is composed of a polarizing plate 21, an interlayer bonding layer 25, and a retarder 22. The polarizing plate 21 and the retarder 22 are bonded together via the interlayer bonding layer 25.

[0081] The polarizing plate 21 may have a linear polarizing layer. The polarizing plate 21 may further include a protective layer provided on one or both sides of the linear polarizing layer. The linear polarizing layer is a layer that transmits linearly polarized light having a vibration plane perpendicular to the absorption axis among unpolarized light. The linear polarizing layer may be, for example, a resin film (such as a polyvinyl alcohol film) on which iodine is adsorbed while being warped and oriented in a certain direction. An optical film 20 including the polarizing plate 21 having a linear polarizing layer and the phase shifter 22 can function as a circular polarizing plate.

[0082] The protective layer constituting the polarizing plate 21 may be, for example, a thermoplastic resin film or an overcoat layer.

[0083] The thermoplastic resin film that can be used as the protective layer can be selected from, for example, cellulose resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyethersulfone resins; polysulfone resins; polycarbonate resins; polyamide resins such as nylon and aromatic polyamide; polyimide resins; polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers; cyclic polyolefin resins having cyclo- and norbornene structures (also referred to as norbornene resins); (meth)acrylic resins; polyarylate resins; polystyrene resins; polyvinyl alcohol resins, and films containing combinations thereof. The thickness of the thermoplastic resin film as the protective layer may be 3 μm or more, or 5 μm or more, and may be 50 μm or less, or 30 μm or less.

[0084] The overcoat layer that can be used as a protective layer may be a layer formed from a photocurable resin or a water-soluble polymer. The overcoat layer may contain a (meth)acrylic resin, a polyvinyl alcohol resin, or a polyamide epoxy resin. The thickness of the overcoat layer may be, for example, 0.1 μm or more and 10 μm or less.

[0085] The retarder 22 is an optical element that exhibits a retardation in the in-plane or thickness direction, and includes one or more retardation films. When the retarder 22 includes two or more retardation films, they may be bonded together with an adhesive or a pressure-sensitive adhesive. The retardation film is a film that exhibits a retardation in the in-plane or thickness direction. The retardation film may be a stretched film or a film containing a cured product of a polymerizable liquid crystal compound.

[0086] A surface protection film may be provided on the polarizing plate 21 of the optical laminate 2. The surface protection film is provided so as to be peelable from the polarizing plate 21. The surface protection film may be a single-layer film or a multilayer film. The surface protection film may be a multilayer film having a base layer and a pressure-sensitive adhesive layer. The expression protection film may be a self-adhesive film.

[0087] The interlayer bonding layer 25 can be a pressure-sensitive adhesive layer or an adhesive layer. When the interlayer bonding layer 25 is a pressure-sensitive adhesive layer, the interlayer bonding layer 25 can be formed using a conventional pressure-sensitive adhesive composition. When the interlayer bonding layer 25 is an adhesive layer, the interlayer bonding layer 25 can be formed using a conventional adhesive such as a water-based adhesive or an active energy ray-curable adhesive. The thickness of the interlayer bonding layer 25 may be, for example, 0.01 μm or more and 10 μm or less.

[0088] In the example of Fig. 2, the pressure-sensitive adhesive layer 10 and the optical film 20 are in direct contact with each other, but a primer layer or the like may be provided between the pressure-sensitive adhesive layer 10 and the optical film 20. The surface of the optical film 20 on the pressure-sensitive adhesive layer 10 side may be activated by, for example, plasma treatment, corona treatment, or the like. An antistatic layer may be provided between the pressure-sensitive adhesive layer 10 and the optical film 20, if necessary.

[0089] Various devices (e.g., image display devices) having an optical film can be manufactured by a method including laminating the pressure-sensitive adhesive layer 10 of the optical laminate 2 shown in Fig. 2 to another adherend. Fig. 3 is a schematic cross-sectional view showing an example of an image display device formed by laminating the pressure-sensitive adhesive layer 10 of the optical laminate 2 to another adherend. The image display device 3 shown in Fig. 3 has an optical film 20, an adherend 30, and a pressure-sensitive adhesive layer 10 interposed between the optical film 20 and the adherend 30. The image display device 3 can be obtained, for example, by a method including peeling off the first release film 11 from the optical laminate 2 of Fig. 2 to expose the pressure-sensitive adhesive layer 10, and laminating the pressure-sensitive adhesive layer 10 to the adherend 30.

[0090] The adherend 30 has a substrate 31 and a metal layer 32 provided on the substrate 31. The pressure-sensitive adhesive layer 10 and the adherend 30 are bonded together with the metal layer 32 facing in a direction in which the pressure-sensitive adhesive layer 10 is in contact with the metal layer 32.

[0091] The metal layer 32 can be, for example, a layer containing aluminum, titanium, copper, silver, gold, iron, tin, zinc, nickel, molybdenum, chromium, tungsten, lead, or an alloy containing two or more metals selected from these. The metal layer 32 may also be a layer containing one or more metals selected from the group consisting of aluminum, titanium, copper, silver, and gold. The metal layer 32 may also be a layer containing aluminum. In this case, the aluminum content in the metal layer 32 may be 30 mass% or more, 50 mass% or more, or even substantially 100 mass% based on the amount of all metal components constituting the metal layer 32. The metal layer 32 may be a single layer or may have a multilayer structure. An example of a multilayer structure includes a three-layer structure consisting of a molybdenum layer / aluminum layer / molybdenum layer.

[0092] The metal layer 32 may be a metal foil, or may be a layer formed by a method such as vacuum deposition, sputtering, ion plating, inkjet printing, or gravure printing. The metal layer 32 may be a layer formed by sputtering, inkjet printing, or gravure printing. Generally, metal layers formed by sputtering tend to corrode relatively easily, but even in this case, corrosion can be sufficiently suppressed.

[0093] The thickness of the metal layer 32 may be, for example, 3 μm or less, 1 μm or less, or 0.8 μm or less, or may be 0.01 μm or more. Suppressing corrosion is particularly effective in preventing damage to the metal layer 32 even when the metal layer 32 is thin.

[0094] The metal layer 32 may be a metal wiring layer forming a wiring pattern. The metal wiring layer may include wiring (i.e., an electrode layer) that constitutes a touch input element of a touch input image display device. The metal wiring layer may include a portion having a width of 10 μm or less, 5 μm or less, or 3 μm or less. The width of the metal wiring layer may be 0.01 μm or more, 0.1 μm or more, or 0.5 μm or more. Suppressing corrosion is particularly effective in preventing damage to the metal layer 32 even when the width is small. When the metal layer 32 is a metal wiring layer, the pressure-sensitive adhesive layer 10 may have a portion that is not in contact with the metal layer 32. The metal layer 32 may form a metal mesh pattern.

[0095] The substrate 31 is not particularly limited and can be any member that constitutes an image display device in which the optical film 20 is incorporated.

[0096] The present invention is not limited to the following examples. In the following examples, the "solids concentration" of various solutions containing a solvent is the ratio of the mass of nonvolatile matter remaining when the solvent is removed from the solution by heating to the mass of the solution. To remove the solvent, for example, the solution contained in a petri dish is heated at 120°C for 4 hours. The solids concentration of a (meth)acrylic resin solution usually substantially corresponds to the concentration of the (meth)acrylic resin.

[0097] The weight-average molecular weight Mw of the (meth)acrylic resin is a value measured by GPC using two columns ("TSKgel GMHHR-H(S)" manufactured by Tosoh Corporation) connected in series, converted into a standard polystyrene value. The GPC conditions are as follows: Eluent: tetrahydrofuran Sample concentration: 2 mg / mL Sample introduction amount: 100 μL Temperature: 40° C. Flow rate: 1 mL / min

[0098] 1. Circularly Polarizing Plate 1-1. Polarizing Plate The following polarizer, first protective film, and second protective film were prepared. Polarizer: Polyvinyl alcohol (PVA) film and a 12 μm-thick linear polarizing layer containing iodine adsorbed thereto First protective film (1): Triacetyl cellulose (TAC) film (thickness: 25 μm) First protective film (2): Laminated film (HC-TAC) composed of a triacetyl cellulose film (thickness: 25 μm) and a hard coat layer (thickness: 7 μm) Second protective film (1): Cycloolefin resin (COP) film (thickness: 13 μm) Second protective film (2): Triacetyl cellulose (TAC) film (thickness: 20 μm) Second protective film (3): Triacetyl cellulose (TAC) film (thickness: 25 μm)

[0099] One surface of each of the first and second protective films was subjected to a corona treatment. An aqueous adhesive was prepared by mixing 100 parts by mass of water, 3 parts by mass of a carboxy-modified polyvinyl alcohol (manufactured by Kuraray Co., Ltd. under the trade name "KL-318"), and 1.5 parts by mass of a polyamide epoxy-based additive, which is a water-soluble epoxy resin (manufactured by Taoka Chemical Co., Ltd. under the trade name "Sumirez Resin 650(30)", an aqueous solution with a solids concentration of 30%).

[0100] Polarizing plates (1), (2), and (3) were prepared by combining the first protective film and the second protective film as shown in Table 1. An aqueous adhesive was applied to one surface of the polarizer. The first protective film was attached to the aqueous adhesive coating with the corona-treated surface facing the aqueous adhesive. The aqueous adhesive was applied to the other surface of the polarizer. The second protective film was attached to the aqueous adhesive coating with the corona-treated surface facing the aqueous adhesive. The formed laminate was dried to obtain a polarizing plate, which was a laminate having a configuration of first protective film / adhesive layer / polarizer / adhesive layer / second protective film.

[0101] 1-2. Retarder (1) Preparation of Laminate A (Laminate having a structure of substrate A / photo-alignment film A / retardation film A) (Composition A for forming a photo-alignment film) A photo-alignment material (weight average molecular weight: 50,000, m:n=50:50), which is a polymer having a structure represented by the following formula, was prepared. 2 parts by mass of the photo-alignment material and 98 parts by mass of cyclopentanone (solvent) were mixed, and the resulting mixture was stirred at 80°C for 1 hour to prepare composition A for forming a photo-alignment film. Photo-alignment material:

[0102] (Retardation Film Forming Composition A) A polymerizable liquid crystal compound (A1) represented by the following formula was prepared according to the method described in JP-A-2019-003177. A polymerizable liquid crystal compound (A2) represented by the following formula was prepared according to the method described in JP-A-2009-173893. Polymerizable liquid crystal compound (A1): Polymerizable liquid crystal compound (A2):

[0103] The polymerizable liquid crystal compound (A1) and the polymerizable liquid crystal compound (A2) were mixed at a mass ratio of 90:10. To 100 parts by mass of the obtained mixture, 0.1 parts by mass of a leveling agent "BYK-361N" (manufactured by BM Chemie) and 3 parts by mass of a photopolymerization initiator ("Irgacure OXE-03", manufactured by BASF Japan Ltd.) were added. N-methyl-2-pyrrolidone (NMP) was added to the mixture to adjust the solid content concentration to 13% by mass. This mixture was stirred at a temperature of 80°C for 1 hour to obtain a retardation film-forming composition A.

[0104] (Laminate A) A biaxially stretched polyethylene terephthalate (PET) film (Diafoil (trade name), manufactured by Mitsubishi Plastics, Inc.) was prepared as the substrate A. The composition A for forming a photo-alignment film was applied to the substrate A using a bar coater. The coating film was dried by heating at 120°C for 2 minutes and cooled to room temperature. The coating film was then irradiated with 100 mJ of polarized ultraviolet light (313 nm reference) using a UV irradiation device (SPOT CURE SP-9, manufactured by Ushio Inc.), thereby forming a photo-alignment film A on the substrate A. The thickness of the photo-alignment film A, measured using an ellipsometer M-220 manufactured by JASCO Corporation, was 100 nm.

[0105] The retardation film-forming composition A was applied onto the photo-alignment film A using a bar coater. The coating film was dried by heating at 120°C for 2 minutes and cooled to room temperature. Then, the coating film was exposed to light at an exposure dose of 500 mJ / cm under a nitrogen atmosphere using a high-pressure mercury lamp ("Uniqure VB-15201BY-A" manufactured by Ushio Inc.). ２ By irradiating the substrate with ultraviolet light of wavelength 365 nm (reference wavelength), a retardation film A was formed as a cured coating film. By irradiating the substrate with ultraviolet light, the polymerizable liquid crystal compound was cured in a state of being aligned horizontally relative to the substrate surface. A laminate A having a structure of substrate A / photo-alignment film A / retardation film A was obtained. The thickness of retardation film A measured using a laser microscope LEXT OLS4100 manufactured by Olympus Corporation was 2.0 μm.

[0106] (2) Preparation of Laminate B (Laminate Having a Configuration of Substrate B / Alignment Film B / Retardation Film B) (Composition B for Forming Alignment Film) 2-butoxyethanol was added to Sunever SE-610 (manufactured by Nissan Chemical Industries, Ltd.), a commercially available alignment polymer, to obtain a composition B for forming an alignment film having a solids concentration of 1% by mass. (Composition B for Forming Retardation Film) 100 parts by mass of a polymerizable liquid crystal compound represented by the following formula (Paliocolor LC242, manufactured by BASF Japan Ltd.), 0.1 parts by mass of a leveling agent (BYK-361N, manufactured by BYK-Chemie), and 2.5 parts by mass of a photopolymerization initiator (Omnirad 907, manufactured by IGM Resin B.V.) were mixed. 400 parts by mass of propylene glycol 1-monomethyl ether 2-acetate (PGME) was further added thereto, and the resulting mixture was stirred at a temperature of 80° C. for 1 hour to prepare a retardation film-forming composition B.

[0107] (Laminate B) A cycloolefin resin (COP) film (ZF14, manufactured by Zeon Corporation) was prepared as the substrate B. One side of the substrate B was corona-treated using a corona treatment device (AGF-B10, manufactured by Kasuga Electric Co., Ltd.). The composition B for forming an alignment film was applied to the corona-treated surface using a bar coater. The coating was dried by heating at 90°C for 1 minute to form an alignment film B. The thickness of the alignment film B measured with a laser microscope was 30 nm.

[0108] The retardation film-forming composition B was applied onto the alignment film B using a bar coater. The coating film was dried by heating at 90°C for 1 minute. Then, the coating film was exposed to light at an exposure dose of 1000 mJ / cm under a nitrogen atmosphere using a high-pressure mercury lamp ("Uniqure VB-15201BY-A" manufactured by Ushio Inc.). ２ The resulting film was irradiated with ultraviolet light of wavelength 365 nm (reference wavelength), thereby forming a cured coating film, namely, a retardation film B. A laminate B having a structure of substrate B / alignment film B / retardation film B was obtained. The thickness of retardation film B measured using a laser microscope LEXT OLS4100 manufactured by Olympus Corporation was 450 nm. (3) Retarder An active energy ray-curable adhesive containing the following components was prepared. (Cationic polymerizable compound) 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (trade name: CEL2021P, manufactured by Daicel Corporation): 70 parts by mass Neopentyl glycol diglycidyl ether (trade name: EX-211, manufactured by Nagase ChemteX Corporation): 20 parts by mass 2-Ethylhexyl glycidyl ether (trade name: EX-121, manufactured by Nagase ChemteX Corporation): 10 parts by mass (Cationic photopolymerization initiator) Trade name: CPI-100 (manufactured by San-Apro Co., Ltd., 50% propylene carbonate solution): 4.5 parts by mass (substantial solid content: 2.25 parts by mass) (Photosensitizing aid) 1,4-diethoxynaphthalene: 2 parts by mass The surfaces of the retardation film A of the laminate A and the retardation film B of the laminate B were each subjected to corona treatment using an AGF-B10 manufactured by Kasuga Electric Co., Ltd. under conditions of an output of 0.3 kW and a treatment speed of 3 m / min. The laminate A and the laminate B were bonded together via the adhesive film, with the corona-treated surfaces of the retardation film A and the retardation film B facing each other. Ultraviolet light (wavelength: 320 nm to 390 nm, UVA: 420 mJ / cm) was applied from the laminate A side. ２ The adhesive was cured by irradiating the adhesive with light, thereby forming an adhesive layer having a thickness of 1.5 μm. By the above procedure, a retarder was obtained, which was a laminate having a structure of substrate A / photo-alignment film A / retardation film A / adhesive layer / retardation film B / alignment film B / substrate B.

[0109] 1-3. Interlayer Laminating Layer A mixed solution containing 100 parts by mass of ethyl acetate, 99.0 parts by mass of butyl acrylate, 0.5 parts by mass of 2-hydroxyethyl acrylate, and 0.5 parts by mass of acrylic acid was placed in a reaction vessel equipped with a cooling tube, a nitrogen inlet tube, a thermometer, and a stirrer. The air in the reaction vessel was replaced with nitrogen gas, while the internal temperature was raised to 55°C. Next, a solution containing 0.12 parts by mass of azobisisobutyronitrile (polymerization initiator) and 10 parts by mass of ethyl acetate was added to the mixed solution in the reaction vessel. After the addition of the polymerization initiator, the internal temperature was maintained at 55°C for 1 hour. Next, while maintaining the internal temperature at 54-56°C, ethyl acetate was continuously added to the reaction vessel at an addition rate of 17.3 parts by mass / hr. The addition of ethyl acetate was stopped when the concentration of the (meth)acrylic resin produced by polymerization reached 35% by mass. The internal temperature was then maintained at 54-56°C for 6 hours after the start of the ethyl acetate addition. Ethyl acetate was then added to the mixed solution in the reaction vessel to obtain a (meth)acrylic resin solution containing a (meth)acrylic resin at a concentration of 20% by mass. The (meth)acrylic resin had a weight average molecular weight Mw of 1,700,000.

[0110] To a (meth)acrylic resin solution containing 80 parts by weight of solids, 20 parts by weight (solids) of a bifunctional acrylate (Shin-Nakamura Chemical Co., Ltd., trade name "A-DOG"), 2.5 parts by weight (solids) of a crosslinker (Mitsui Chemicals, trade name "D-101E", an ethyl acetate solution of a trimethylolpropane adduct of tolylene diisocyanate, solids concentration: 75% by weight), 1.5 parts by weight of a photopolymerization initiator (Ciba Specialty Chemicals, trade name "Irgacure 500"), and 0.3 parts by weight of a silane coupling agent (Shin-Etsu Chemical Co., Ltd., trade name "KBM-403") were added. Ethyl acetate was further added to obtain a composition for forming an interlayer bonding layer with a solids concentration of 13% by weight. A-DOG is a diacrylate of an acetal compound of hydroxypivalaldehyde and trimethylolpropane, and has a structure represented by the following formula:

[0111] A release film (polyethylene terephthalate film, Mitsubishi Chemical, MRV (V04), thickness: 38 μm) having a release-treated surface was prepared. A composition for forming an interlayer bonding layer was applied to the release-treated surface of the release film using an applicator. The coating film was dried by heating at 100°C for 1 minute to form an interlayer bonding layer with a thickness of 5 μm. The surface of the interlayer bonding layer opposite to the release film side was bonded to the release-treated surface of a release film (polyethylene terephthalate film, Mitsubishi Chemical, MRF, thickness: 38 μm). Subsequently, ultraviolet light was irradiated under the following conditions to crosslink the (meth)acrylic resin in the interlayer bonding layer. UV irradiation conditions Device: Fusion UV Lamp System (manufactured by Fusion UV Systems, using H bulb) Integrated light intensity of UVA: 250 mJ / cm ２ (Measurement instrument: UV Power Puck II manufactured by FusionUV)

[0112] 1-4. Circular Polarizing Plate The surface of the second protective film of the polarizing plate was subjected to corona treatment using a corona treatment device (AGF-B10 manufactured by Kasuga Electric Co., Ltd.) under conditions of an output of 0.3 kW and a treatment speed of 3 m / min. The substrate A was peeled from the retarder, and the exposed surface of the photo-alignment film A was subjected to corona treatment under the same conditions. The polarizing plate and the retarder were bonded together via an interlayer laminating layer, with the corona-treated surfaces facing each other. Next, the substrate B of the retarder was peeled off to obtain a circular polarizing plate (optical film) that was a laminate having a configuration of polarizing plate / interlayer laminating layer / photo-alignment film A / retardation film A / adhesive layer / retardation film B / alignment film B.

[0113] 2. Pressure-Sensitive Adhesive Sheet 2-1. (Meth)acrylic Resin Solution (Meth)acrylic Resin Solution (1) A monomer mixture prepared by diluting 42.5 parts by mass of n-butyl acrylate, 5 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of methyl acrylate, 30 parts by mass of 2-methoxyethyl acrylate, 1.0 part by mass of 2-hydroxyethyl acrylate, and 1.5 parts by mass of acrylic acid with ethyl acetate was placed in a reaction vessel equipped with a cooling tube, a nitrogen inlet tube, a thermometer, and a stirrer. The internal temperature was raised to 55°C while the air in the reaction vessel was replaced with nitrogen gas. Next, an ethyl acetate solution of azobisisobutyronitrile was added as a polymerization initiator to the monomer mixture in the reaction vessel. The ethyl acetate solution was added in an amount such that 0.3 parts by mass of azobisisobutyronitrile was added per 100 parts by mass of the total amount of monomers. After the addition of the polymerization initiator, the internal temperature was maintained at 55°C for 1 hour. Next, while maintaining the internal temperature at 54-56°C, ethyl acetate was continuously added to the reaction vessel at an addition rate of 17.3 parts by mass / hr. The addition of ethyl acetate was stopped when the concentration of the (meth)acrylic resin (a copolymer of n-butyl acrylate / 2-ethylhexyl acrylate / methyl acrylate / 2-methoxyethyl acrylate / 2-hydroxyethyl acrylate / acrylic acid) produced by polymerization reached 35% by mass. The internal temperature was then maintained at 55°C for 12 hours after the start of the ethyl acetate addition. Ethyl acetate was then added to the mixture in the reaction vessel to obtain a (meth)acrylic resin solution (1) with a solids concentration of 20% by mass. The weight-average molecular weight (Mw) of the (meth)acrylic resin was 1.58 million.

[0114] (Meth)acrylic resin solutions (2) to (5) (Meth)acrylic resin solutions (2) to (5) were obtained in the same manner as (meth)acrylic resin solution (1), except that the type and amount (parts by mass) of the monomer were changed as shown in Table 2. The amount of the monomer shown in Table 2 is the amount of each monomer charged relative to 100 parts by mass of the total amount of the monomers, and this roughly corresponds to the proportion (% by mass) of the monomer units derived from each monomer based on the total amount of the monomer units constituting the (meth)acrylic resin.

[0115] The monomers shown in the table are as follows: BA: n-butyl acrylate, 2EHA: 2-ethylhexyl acrylate, MA: methyl acrylate, MEA: 2-methoxyethyl acrylate (alkoxyalkyl (meth)acrylate), HEA: 2-hydroxyethyl acrylate, AA: acrylic acid.

[0116] 2-2. Pressure-sensitive adhesive composition Pressure-sensitive adhesive composition (1) To an amount of (meth)acrylic resin solution (1) corresponding to 100 parts by mass of the solid content ((meth)acrylic resin), an ethyl acetate solution (solid content concentration 75% by mass) containing 0.5 parts by mass of a trimethylolpropane adduct of tolylene diisocyanate (crosslinking agent, Mitsui Chemicals, Inc., product name "D-103"), 0.5 parts by mass of 3-glycidoxypropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., product name "KBM-403"), and 0.34 parts by mass of an ionic compound of tetrakispentafluorophenyl borate (anion) and decylpyridium (cation) were added. Methyl ethyl ketone was further added thereto to obtain pressure-sensitive adhesive composition (1) (solid content concentration 14% by mass).

[0117] Pressure-sensitive adhesive compositions (2) to (5), (a), and (b) Pressure-sensitive adhesive compositions (2) to (5), (a), and (b) each having a solid content concentration of 14 mass% were obtained in the same manner as for pressure-sensitive adhesive composition (1), except that the (meth)acrylic resin solution and the type and content of the ionic compound were changed as shown in Table 3.

[0118]

[0119] 2-3. Pressure-sensitive adhesive sheet Each pressure-sensitive adhesive composition was applied using an applicator to the release-treated surface of a first release film (manufactured by Mitsubishi Chemical Corporation, trade name "MRV38 (V04)", thickness: 38 μm). The coating was dried by heating at 100°C for 1 minute to form a pressure-sensitive adhesive layer with a thickness of 15 μm. A second release film (manufactured by Mitsubishi Chemical Corporation, trade name "MRF38", thickness: 38 μm) was laminated on the surface of the pressure-sensitive adhesive layer opposite the release film, with the release-treated surface facing the pressure-sensitive adhesive layer. The obtained laminate was left to stand for 7 days or more in an environment at a temperature of 23°C and a relative humidity of 60%, to obtain a pressure-sensitive adhesive sheet having a configuration of first release film / pressure-sensitive adhesive layer / second release film, wherein the pressure-sensitive adhesive layer was a laminate formed from pressure-sensitive adhesive compositions (1) to (5), (a) or (b).

[0120] 3. Circularly polarizing plate with adhesive (optical laminate) The second release film was peeled off from each of the prepared adhesive sheets. The exposed surface of the adhesive layer was corona-treated using a corona treatment device (AGF-B10 manufactured by Kasuga Electric Co., Ltd.) at an output of 0.3 kW and a treatment speed of 3 m / min. The surface of alignment film B of the circular polarizing plate was corona-treated under the same conditions. The corona-treated surface of the adhesive layer and the corona-treated surface of alignment film B of the circular polarizing plate were bonded together to obtain an adhesive-attached circular polarizing plate of the Examples or Comparative Examples, which is an optical laminate having a circular polarizing plate / adhesive layer / first release film configuration. Table 4 shows the combinations of polarizing plate and adhesive composition in each Example and Comparative Example.

[0121] 4. Evaluation 4-1. Surface Resistivity The second release film was peeled off from each pressure-sensitive adhesive sheet, and the exposed pressure-sensitive adhesive layer was bonded to a polyethylene terephthalate (PET) film (thickness: 50 μm) to obtain a pressure-sensitive adhesive PET film. The obtained pressure-sensitive adhesive PET film was cut into a size of 40 mm x 40 mm. The first release film was peeled off from the cut pressure-sensitive adhesive PET film. The surface resistance was measured by contacting the probe of a surface resistance measurement device (manufactured by Mitsubishi Chemical Corporation, product name "Hiresta-up MCP-HT450") with the surface of the exposed pressure-sensitive adhesive layer. The measurement conditions were an applied voltage of 100 V and an application time of 30 seconds. The measurement results are shown in Table 4.

[0122] 4-1. Corrosion Area Ratio A metal-layered glass substrate (manufactured by Geomatec Co., Ltd.) was prepared. The glass substrate consisted of a glass substrate made of alkali-free glass and a metal layer containing a titanium-aluminum alloy, approximately 500 nm thick, formed on the surface of the glass substrate by sputtering. A circular polarizer with adhesive was cut into a size of 30 mm x 30 mm. The first release film was peeled off from the cut circular polarizer with adhesive to expose the adhesive layer. The circular polarizer with adhesive and the glass substrate with metal layer were bonded together, with the exposed surface of the adhesive layer facing the metal layer. The formed laminate structure (glass substrate / metal layer / adhesive layer / circular polarizer) was heated and pressurized in an autoclave at a temperature of 50°C and a pressure of 0.49 MPa, thereby producing a test specimen for evaluating metal corrosion. The test specimen was stored for 100 hours in an environment at a temperature of 85°C and a relative humidity of 98%. After storage, the test piece was irradiated with light from the glass substrate side, and the metal layer was observed from the circular polarizer side to determine the area of ​​the light-transmitting portion. The light-transmitting portion corresponds to the portion of the metal layer where corrosion has progressed. The total area of ​​the metal layer is A1, and the area of ​​the light-transmitting portion is A2, and the corrosion area ratio Ac was calculated using the following formula: Ac [%] = (A2 / A1) x 100 The measurement results are shown in Table 4. If the corrosion area ratio is less than 1.4%, for example, it can be said that metal corrosion is appropriately suppressed. The corrosion area ratio may be 1.15% or less, 1.0% or less, or 0.9% or less.

[0123]

[0124] 1...adhesive sheet, 2...optical laminate, 3...image display device, 10...adhesive layer, 11...first release film, 12...second release film, 20...optical film, 21...polarizing plate, 22...phase shifter, 25...interlayer bonding layer, 30...adherend, 31...substrate, 32...metal layer

Claims

1. A pressure-sensitive adhesive composition containing a (meth)acrylic resin and an ionic compound, wherein the (meth)acrylic resin is a copolymer containing monomer units derived from an alkoxyalkyl (meth)acrylate in a proportion of 1% by mass to 40% by mass based on the total amount of monomer units constituting the (meth)acrylic resin, and the ionic compound has an anion having a pentafluorophenyl group and a cation.

2. The pressure-sensitive adhesive composition according to claim 1, wherein the (meth)acrylic resin contains monomer units derived from an alkyl (meth)acrylate having an alkyl group having 1 to 3 carbon atoms in a proportion of 5% by mass or more and 50% by mass or less based on the total amount of monomer units constituting the (meth)acrylic resin.

3. The pressure-sensitive adhesive composition according to claim 1, wherein the (meth)acrylic resin contains monomer units derived from a monomer that forms a homopolymer having a glass transition temperature of 0°C or higher in a proportion of 5% by mass or more and 50% by mass or less based on the total amount of monomer units constituting the (meth)acrylic resin.

4. The pressure-sensitive adhesive composition according to claim 1, wherein the (meth)acrylic resin contains monomer units derived from a monomer having a carboxy group or an acid anhydride group in a proportion of 0.6 mass % or more and 10 mass % or less based on the total amount of monomer units constituting the (meth)acrylic resin.

5. The pressure-sensitive adhesive composition according to claim 1, wherein the content of the ionic compound is 0.1 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the (meth)acrylic resin.

6. The pressure-sensitive adhesive composition according to claim 1, wherein the melting point of the ionic compound is 23°C or higher.

7. The pressure-sensitive adhesive composition according to claim 1, wherein the anion of the ionic compound contains a boron atom.

8. The pressure-sensitive adhesive composition according to claim 1, wherein the cation of the ionic compound is an organic cation.

9. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition according to any one of claims 1 to 8.

10. The pressure-sensitive adhesive sheet according to claim 9, wherein the thickness of the pressure-sensitive adhesive layer is 2 μm or more and 50 μm or less.

11. An optical laminate comprising a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition according to any one of claims 1 to 8, and an optical film attached to the pressure-sensitive adhesive layer.

12. The optical laminate according to claim 11, wherein the optical film is a polarizing plate.

13. The optical laminate according to claim 12, wherein the polarizing plate includes a retarder.

14. An image display device comprising: the optical laminate according to claim 11; and a metal layer in contact with the pressure-sensitive adhesive layer of the optical laminate.

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