Adhesive compositions, adhesive sheets, and optical components

Abstract

One embodiment of the present invention relates to an adhesive agent composition, an adhesive sheet or an optical member. The adhesive agent composition contains: an acrylic polymer (A) which contains more than 0% by mass but not more than 0.4% by mass of constituent units derived from a hydroxyl group-containing monomer and an amino group-containing monomer, while having an acid value of 1.0 mgKOH / g or less and an Mw of 600,000 or more; an acrylic polymer (B) which contains 0.05% by mass or less of constituent units derived from a hydroxyl group-containing monomer and an amino group-containing monomer, while having an acid value of 1.0 mgKOH / g or less and an Mw of more than 250,000 but less than the Mw of the component (A); and an isocyanate-based curing agent (C). With respect to this adhesive agent composition, 10 parts by mass or more of the component (B) is contained relative to 100 parts by mass of the component (A); and more than 6 parts by mass but less than 30 parts by mass of the component (C) is contained relative to a total of 100 parts by mass of the components (A) and (B).

Description

[Technical Field]

[0001] One embodiment of the present invention relates to an adhesive composition, an adhesive sheet, or an optical component. [Background technology]

[0002] Display devices such as liquid crystal displays use optical components such as polarizing plates and phase difference plates, and these optical components are usually attached to other components such as glass or plastic via an adhesive layer obtained from an adhesive composition. Since the aforementioned display devices are used in a variety of environments, the adhesive layer used as the bonding layer is required to exhibit desired properties such as heat resistance, cohesiveness, and adhesion in a variety of environments. Among these various environments, for example, the interior of a car or other vehicle can be considered a harsh environment that can become hot and humid.

[0003] As adhesive compositions that exhibit desired properties under high temperature and high humidity, for example, Patent Documents 1 and 2 disclose adhesive compositions using acrylic polymers having carboxyl groups. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2014-196376 [Patent Document 2] Japanese Patent Publication No. 2015-117344 [Overview of the project] [Problems that the invention aims to solve]

[0005] The adhesive layer used in display devices and the like installed inside vehicles such as automobiles requires durability at, for example, 115°C. However, in the 115°C temperature range, adhesive layers obtained from conventional adhesive compositions, such as those disclosed in Patent Documents 1 and 2, have a poor balance between cohesive force and stress relaxation properties. This can lead to foaming due to decreased cohesive force, peeling from the adherend due to decreased stress relaxation properties, and even problems such as light leakage. Therefore, it has been found that there is room for improvement in conventional adhesive compositions in terms of high-temperature durability.

[0006] Furthermore, the adhesive layer may be required to have a moderate level of adhesive strength so that when used by adhering it to a substrate, it does not peel off or lift away from the substrate, and when it is desired to remove it from the substrate, it can be removed without leaving any adhesive residue (excellent reworkability). Furthermore, the adhesive layer may be used in contact with corrosive substrates such as metals used in electrodes or metal oxides such as ITO (indium tin oxide). In such cases, it is also required that the adhesive layer not corrode the corrosive substrate.

[0007] One embodiment of the present invention provides an adhesive composition that can suppress corrosion of a corrosive substrate even when in contact with the substrate, has appropriate adhesive strength, and can form an adhesive layer that is resistant to foaming and peeling from the substrate even under high temperature and high humidity conditions. [Means for solving the problem]

[0008] The inventors diligently studied to solve the aforementioned problems. As a result, they found that the following configuration can solve the aforementioned problems. An example of the configuration of the present invention is as follows.

[0009] [1] It contains a structural unit derived from a hydroxyl group-containing monomer (a1) and a structural unit derived from an amino group-containing monomer (a2) in a total amount exceeding 0% by mass and not exceeding 0.4% by mass, and has an acid value of 1.0 mgKOH / g or less, an acrylic polymer (A) having a weight average molecular weight (Mw) of 600,000 or more, The total content of the structural unit derived from the hydroxyl group-containing monomer (b1) and the structural unit derived from the amino group-containing monomer (b2) is 0.05% by mass or less, has an acid value of 1.0 mgKOH / g or less, has a weight average molecular weight (Mw) exceeding 250,000, and is smaller than the Mw of the acrylic polymer (A), an acrylic polymer (B), and an isocyanate-based curing agent (C). It contains, with respect to 100 parts by mass of the acrylic polymer (A), the acrylic polymer (B) is contained in an amount of 10 parts by mass or more. with respect to a total of 100 parts by mass of the acrylic polymer (A) and the acrylic polymer (B), the isocyanate-based curing agent (C) is contained in an amount exceeding 6 parts by mass and less than 30 parts by mass. An adhesive composition.

[0010] [2] The adhesive composition according to [1], wherein the acrylic polymer (A) contains 25 to 99.99% by mass of a structural unit derived from at least one monomer (a3) selected from alkyl (meth)acrylate and alkoxyalkyl (meth)acrylate.

[0011] [3] The adhesive composition according to [1] or [2], wherein the acrylic polymer (B) contains 25 to 100% by mass of a structural unit derived from at least one monomer (b3) selected from alkyl (meth)acrylate and alkoxyalkyl (meth)acrylate.

[0012] [4] The adhesive composition according to any one of [1] to [3], wherein the acrylic polymer (A) contains a structural unit derived from the hydroxyl group-containing monomer (a1) in an amount exceeding 0% by mass and not exceeding 0.4% by mass.

[0013] [5] The adhesive composition according to any one of [1] to [4], wherein the acrylic polymer (A) contains 25 to 98% by mass of structural units derived from at least one monomer (a3) ​​selected from alkyl (meth)acrylate and alkoxyalkyl (meth)acrylate, and contains 1 to 50% by mass of structural units derived from at least one monomer (a4) selected from alicyclic hydrocarbon group-containing (meth)acrylate and aromatic hydrocarbon group-containing (meth)acrylate.

[0014] [6] The adhesive composition according to any one of [1] to [5], wherein the acrylic polymer (B) contains 25 to 98% by mass of structural units derived from at least one monomer (b3) selected from alkyl (meth)acrylate and alkoxyalkyl (meth)acrylate, and 1 to 50% by mass of structural units derived from at least one monomer (b4) selected from alicyclic hydrocarbon group-containing (meth)acrylate and aromatic hydrocarbon group-containing (meth)acrylate.

[0015] [7] The adhesive composition according to any one of [1] to [6], further comprising a curing agent (D) other than the isocyanate-based curing agent (C).

[0016] [8] The adhesive composition according to any one of [1] to [7], further comprising a silane coupling agent (E).

[0017] [9] The adhesive composition according to any one of [1] to [8], further comprising an antistatic agent (F).

[0018]

[10] An adhesive composition according to any one of [1] to [9], used in optical components.

[0019]

[11] An adhesive sheet having an adhesive layer obtained from any of the adhesive compositions described in [1] to

[10] .

[12] An optical member having an adhesive layer obtained from any of the adhesive compositions described in [1] to

[10] . [Effects of the Invention]

[0020] According to one embodiment of the present invention, even when in contact with a corrosive substrate, corrosion of the substrate can be suppressed, and an adhesive layer can be formed that has appropriate adhesive strength, exhibits a good balance of cohesive force and stress relaxation even under high temperature and high humidity conditions, and is resistant to foaming and peeling from the substrate. Furthermore, according to one embodiment of the present invention, an adhesive layer with excellent reworkability can be formed, and when the resulting adhesive layer is used in an optical component such as a polarizing plate, light leakage from the optical component can be sufficiently suppressed. [Modes for carrying out the invention]

[0021] Adhesive Composition An adhesive composition according to one embodiment of the present invention (hereinafter also referred to as "this composition") contains a total of 0% by mass and 0.4% by mass or less of constituent units derived from a hydroxyl group-containing monomer (a1) and an amino group-containing monomer (a2), and has an acid value of 1.0 mgKOH / g or less, and an acrylic polymer (A) with a weight-average molecular weight (Mw) of 600,000 or more, An acrylic polymer (B) having a total content of constituent units derived from a hydroxyl group-containing monomer (b1) and constituent units derived from an amino group-containing monomer (b2) of 0.05% by mass or less, an acid value of 1.0 mgKOH / g or less, a weight-average molecular weight (Mw) greater than 250,000, and an Mw smaller than that of the acrylic polymer (A), Isocyanate-based curing agent (C) and An adhesive composition containing, The acrylic polymer (B) is contained in an amount of 10 parts by mass or more per 100 parts by mass of the acrylic polymer (A), The isocyanate-based curing agent (C) is contained in an amount exceeding 6 parts by mass but less than 30 parts by mass, with respect to a total of 100 parts by mass of the acrylic polymer (A) and acrylic polymer (B).

[0022] In the present invention, "acrylic polymer" refers to a polymer in which the total amount of constituent units derived from acrylic acid, acrylate salts, acrylic acid esters, methacrylic acid, methacrylate salts, and methacrylic acid esters is 50% by mass or more, relative to 100% by mass of all constituent units of the acrylic polymer.

[0023] In this specification, (meth)acrylic is used as a general term for acrylic and methacrylic, and may refer to either acrylic or methacrylic. Similarly, (meth)acrylate is used as a general term for acrylate and methacrylate, and may refer to either acrylate or methacrylate. Furthermore, (meth)acryloyl is used as a general term for acryloyl and methacryloyl, and may refer to either acryloyl or methacryloyl.

[0024] <Acrylic polymer (A)> The acrylic polymer (A) (hereinafter also referred to as "polymer (A)") contains a total of more than 0% by mass and 0.4% by mass or less of constituent units derived from hydroxyl group-containing monomer (a1) (hereinafter also referred to as "monomer (a1)") and constituent units derived from amino group-containing monomer (a2) (hereinafter also referred to as "monomer (a2)"), has an acid value of 1.0 mgKOH / g or less, and has an Mw of 600,000 or more. By using such a polymer (A), corrosion of the adherend can be suppressed even when in contact with a corrosive adherend, and the crosslinking density of the resulting adhesive layer can be reduced. As a result, an adhesive layer with excellent stress relaxation properties and resistance to peeling from the adherend can be easily formed.

[0025] The total content of constituent units derived from monomer (a1) and monomer (a2) in polymer (A), preferably the content of constituent units derived from monomer (a1) in polymer (A), is greater than 0% by mass and less than or equal to 0.4% by mass, preferably less than or equal to 0.2% by mass, more preferably less than or equal to 0.15% by mass, preferably 0.001% by mass or more, and more preferably 0.002% by mass or more, based on 100% by mass of all constituent units in polymer (A). When the content is within the aforementioned range, the resulting adhesive layer has a low crosslinking density, exhibits excellent stress relaxation properties, and can easily form an adhesive layer that is less prone to peeling of the adherend. In particular, when the content is within the aforementioned range, if the adhesive layer is used in contact with an adherend that can shrink significantly (e.g., a polarizing plate), the stress on the adhesive layer can be relaxed, and the shrinkage of the adherend can be further suppressed. The content of constituent units derived from monomer (a1) and monomer (a2) can be calculated from the amounts of monomer (a1) and monomer (a2) in the monomer components used when synthesizing polymer (A).

[0026] [Hydroxygroup-containing monomer (a1)] Polymer (A) can be synthesized by polymerizing a monomer component containing at least one selected from monomer (a1) and monomer (a2), but it is preferable that the monomer component contains monomer (a1). Monomer (a1) may be used alone or in combination of two or more types.

[0027] Examples of monomers (a1) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-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.

[0028] [Amino group-containing monomer (a2)] Polymer (A) can be synthesized by polymerizing a monomer component containing at least one selected from monomer (a1) and monomer (a2), but it is preferable that the monomer component does not contain monomer (a2). Monomer (a2) may be used alone or in combination of two or more. Monomer (a2) is a monomer other than monomer (a1). Since amide and imide groups are not typically included in amino groups, in this invention, a monomer having an amide or imide group and no other amino groups is not monomer (a2).

[0029] Examples of monomers (a2) include dialkylaminoalkyl(meth)acrylates such as dimethylaminoethyl(meth)acrylate and diethylaminoethyl(meth)acrylate.

[0030] [Alkyl (meth)acrylates and alkoxyalkyl (meth)acrylates] Polymer (A) preferably further contains a constituent unit derived from at least one monomer (a3) ​​selected from alkyl (meth)acrylates and alkoxyalkyl (meth)acrylates (hereinafter also referred to as "monomer (a3)"), and is particularly preferably derived from alkyl (meth)acrylates and alkoxyalkyl (meth)acrylates. Monomer (a3) ​​is a monomer other than monomer (a1), monomer (a2), and monomer (a4) described below. By including alkyl (meth)acrylate-derived structural units in polymer (A), the tackiness and reworkability (ability to reposition) of the resulting adhesive layer can be easily adjusted. Furthermore, because polymer (A) contains structural units derived from alkoxyalkyl (meth)acrylate, the time it takes for the physical properties (e.g., gel fraction) of the resulting adhesive layer to stabilize is shortened (hereinafter also referred to as "excellent aging properties"), making it possible to efficiently form an adhesive layer with excellent quality stability. The gel fraction can be measured specifically by the method described in the following examples.

[0031] When polymer (A) contains constituent units derived from monomer (a3), the content of constituent units derived from monomer (a3) ​​is preferably 25 to 99.99% by mass, more preferably 50 to 99.99% by mass, relative to 100% by mass of all constituent units of polymer (A), in order to better exhibit the above-mentioned effects. When polymer (A) contains constituent units other than those derived from monomer (a1), monomer (a2), and monomer (a3), in particular when it contains constituent units derived from monomer (a1), monomer (a2), monomer (a3), and monomer (a4) described below, the upper limit of the content of constituent units derived from monomer (a3) ​​is preferably 98% by mass or less, more preferably 97% by mass or less, and the lower limit is preferably 25% by mass or more, more preferably 50% by mass or more. The content of constituent units derived from monomer (a3) ​​can be calculated from the amount of monomer (a3) ​​in the monomer components used when synthesizing polymer (A).

[0032] Examples of the alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, iso-propyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-propyl (meth)acrylate. Examples include alkyl(meth)acrylates with 1 to 20 carbon atoms, such as ctyl(meth)acrylate, iso-octyl(meth)acrylate, nonyl(meth)acrylate, iso-nonyl(meth)acrylate, decyl(meth)acrylate, iso-decyl(meth)acrylate, undeca(meth)acrylate, lauryl(meth)acrylate, oleyl(meth)acrylate, n-stearyl(meth)acrylate, and iso-stearyl(meth)acrylate. The number of carbon atoms in the alkyl(meth)acrylate is preferably 1 to 12, more preferably 1 to 8. Alkyl (meth)acrylates may be used individually or in combination of two or more types.

[0033] Examples of the alkoxyalkyl (meth)acrylate include methoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, and 4-ethoxybutyl (meth)acrylate. Alkoxyalkyl (meth)acrylates may be used individually or in combination of two or more types.

[0034] [Alicyclic hydrocarbon group-containing (meth)acrylates and aromatic hydrocarbon group-containing (meth)acrylates] Polymer (A) may further contain constituent units derived from at least one monomer (a4) (hereinafter also referred to as "monomer (a4)") selected from alicyclic hydrocarbon group-containing (meth)acrylates and aromatic hydrocarbon group-containing (meth)acrylates. Monomer (a4) is a monomer other than monomer (a1) and monomer (a2). By including structural units derived from alicyclic hydrocarbon group-containing (meth)acrylate in polymer (A), the cohesive force and stress relaxation properties of the resulting adhesive layer can be easily adjusted. Furthermore, because polymer (A) contains structural units derived from aromatic hydrocarbon group-containing (meth)acrylate, it is possible to easily form an adhesive layer that exhibits superior adhesion to the adherend and suppresses light leakage.

[0035] When polymer (A) contains constituent units derived from monomer (a4), the content of constituent units derived from monomer (a4) is preferably 1 to 50% by mass, more preferably 1 to 30% by mass, relative to 100% by mass of the total constituent units of polymer (A), in order to better exhibit the above-mentioned effects. The content of constituent units derived from monomer (a4) can be calculated from the amount of monomer (a4) in the monomer components used when synthesizing polymer (A).

[0036] Examples of the alicyclic hydrocarbon group-containing (meth)acrylate include cyclohexyl (meth)acrylate, 4-t-butylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and adamantyl (meth)acrylate. The alicyclic hydrocarbon group-containing (meth)acrylate may be used alone or in combination of two or more types.

[0037] Examples of the aromatic hydrocarbon group-containing (meth)acrylate include benzyl (meth)acrylate, phenyl (meth)acrylate, and phenoxyethyl (meth)acrylate. Aromatic hydrocarbon group-containing (meth)acrylates may be used individually or in combination of two or more types.

[0038] [Other monomers] Polymer (A) may further contain other monomer-derived constituent units other than monomer (a1), monomer (a2), monomer (a3), and monomer (a4), to the extent that it does not impair the objectives of the present invention. The content of the aforementioned other monomer-derived constituent units is preferably 30% by mass or less, and more preferably 20% by mass or less, relative to 100% by mass of the total constituent units of polymer (A), in order to better exhibit the aforementioned effects. The content of constituent units derived from other monomers can be calculated from the amount of other monomers in the monomer components used when synthesizing polymer (A).

[0039] Other monomers include, for example, (meth)acrylamide; N-alkyl(meth)acrylamides such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, N-hexyl(meth)acrylamide; N,N-dialkyl(meth)acrylamides such as N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide; amide group-containing monomers such as cyclic amide group-containing monomers such as N-vinylpyrrolidone, N-vinylcaprolactam, (meth)acryloylmorpholine: Nitrogen-containing heterocyclic monomers such as N-cyclohexylmaleimide, N-phenylmaleimide, N-laurylmaleimide, and N-benzylmaleimide: Cyano group-containing monomers such as acrylonitrile and methacrylonitrile: Styrene, α-methylstyrene, p-methylstyrene, p-chlorostyrene, p-chloromethylstyrene, p-methoxystyrene, p-tert-butoxystyrene, divinylbenzene, indene, and other styrene and styrene derivatives: Vinyl ester compounds such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl benzoate, and vinyl diatomaceous earth: These are some examples. Other monomers may be used individually or in combination of two or more.

[0040] Among the other monomers mentioned above, amide group-containing monomers and nitrogen-based heterocyclic monomers are preferred. By using polymer (A) containing structural units derived from these monomers, an adhesive layer with excellent aging properties and quality stability can be formed productively.

[0041] [Method for synthesizing polymer (A)] Polymer (A) can be synthesized by polymerizing the aforementioned monomer components, and may be a random polymer, block polymer, or graft polymer, and can be synthesized by various polymerization methods. The polymerization method is not particularly limited, but examples include solution polymerization, emulsion polymerization, and suspension polymerization. Among these, when producing the present composition using a mixture of copolymers obtained by polymerization, polymerization by solution polymerization is preferred from the viewpoint that the processing steps are relatively simple and can be carried out in a short time.

[0042] A specific example of solution polymerization involves placing monomer components, polymerization initiators, and other components such as chain transfer agents and polymerization solvents in a reaction vessel, setting the reaction start temperature to typically 40°C or higher, preferably 50°C or higher, typically 100°C or lower, and preferably 80°C or lower, and maintaining the reaction system at a temperature of typically 50-90°C, preferably 60-90°C, for 2-20 hours. The reaction is carried out, for example, under an inert gas atmosphere such as nitrogen gas. In addition, at least one selected from monomer components, polymerization initiators, chain transfer agents, and polymerization solvents may be added during the polymerization reaction.

[0043] Examples of polymerization initiators include azo-based initiators and peroxide-based polymerization initiators. Examples of azo initiators include 2,2'-azobisisobutyronitrile, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitride), 2-(carbamoylazo)isobutyronitrile, 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, and 2,2'-azobis(2- Examples of azo compounds include amidinopropane dihydrochloride, 2,2'-azobis(N,N'-methylene isobutylamidine), 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide], 2,2'-azobis(isobutylamide) dihydrate, 4,4'-azobis(4-cyanopentanoic acid), 2,2'-azobis(2-cyanopropanol), dimethyl-2,2'-azobis(2-methylpropionate), and 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide).

[0044] Examples of peroxide-based polymerization initiators include t-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, di-i-propyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, t-butyl peroxypivalate, and 2,2-bis(4,4-di-t-butyl peroxycyclohexyl peroxide). Examples include propane, 2,2-bis(4,4-di-t-amyl peroxycyclohexyl)propane, 2,2-bis(4,4-di-t-octyl peroxycyclohexyl)propane, 2,2-bis(4,4-di-α-cumyl peroxycyclohexyl)propane, 2,2-bis(4,4-di-t-butyl peroxycyclohexyl)butane, and 2,2-bis(4,4-di-t-octyl peroxycyclohexyl)butane.

[0045] Polymerization initiators may be used individually or in combination of two or more. Furthermore, polymerization initiators may be added multiple times during polymerization. The amount of polymerization initiator used is usually 0.001 parts by mass or more, preferably 0.005 parts by mass or more, and usually 5 parts by mass or less, preferably 3 parts by mass or less, per 100 parts by mass of monomer component.

[0046] Examples of polymerization solvents used in solution polymerization include aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, and n-octane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, cycloheptane, and cyclooctane; ethers such as diethyl ether, diisopropyl ether, 1,2-dimethoxyethane, dibutyl ether, tetrahydrofuran, dioxane, anisole, phenylethyl ether, and diphenyl ether; halogenated hydrocarbons such as chloroform, carbon tetrachloride, 1,2-dichloroethane, and chlorobenzene; esters such as ethyl acetate, propyl acetate, butyl acetate, and methyl propionate; ketones such as acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, and cyclohexanone; amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; nitriles such as acetonitrile and benzonitrile; and sulfoxides such as dimethyl sulfoxide and sulfolane. The polymerization solvent may be used alone or in combination of two or more types.

[0047] [Properties of polymer (A)] The weight-average molecular weight (Mw) of polymer (A), as measured by gel permeation chromatography (GPC), is 600,000 or more, preferably 800,000 or more, more preferably 1,000,000 or more, preferably 3,000,000 or less, and more preferably 2,500,000 or less. When Mw is within the aforementioned range, an adhesive layer with excellent durability and cohesive strength can be easily formed. The Mw can be measured specifically by the method described in the following examples.

[0048] The acid value of polymer (A) is 1.0 mg KOH / g or less, preferably 0.8 mg KOH / g or less, and more preferably 0 mg KOH / g. When the acid value of polymer (A) is within the above range, corrosion of the adherend in contact with the adhesive layer formed from the resulting adhesive composition can be suppressed. The acid value can be measured specifically by the method described in the following examples.

[0049] A polymer (A) having an acid value within the above range can be synthesized, for example, by using an acidic group-containing monomer of 0.12% by mass or less per 100% by mass of the monomer component when synthesizing polymer (A), or preferably by substantially not using an acidic group-containing monomer. Examples of acidic group-containing monomers include acrylic acid, methacrylic acid, β-carboxyethyl (meth)acrylate, 5-carboxypentyl (meth)acrylate, mono(meth)acryloyloxyethyl succinate, ω-carboxypolycaprolactone mono(meth)acrylate, crotonic acid, maleic acid, fumaric acid, itaconic acid, and citraconic acid, which are carboxyl group-containing monomers.

[0050] [Polymer (A) content] This composition may contain one or more polymers (A). The polymer (A) content in this composition is preferably 20% by mass or more, more preferably 25% by mass or more, preferably 70% by mass or less, and more preferably 65% ​​by mass or less, based on 100% by mass of the nonvolatile content of this composition. When the polymer (A) content is within the aforementioned range, an adhesive layer can be easily formed that has appropriate adhesive strength, exhibits a good balance of cohesive force and stress relaxation even under high temperature and high humidity conditions, and is resistant to foaming and peeling from the adherend.

[0051] <Acrylic polymer (B)> Acrylic polymer (B) (hereinafter also referred to as "polymer (B)") is a polymer in which the total content of constituent units derived from hydroxyl group-containing monomer (b1) (hereinafter also referred to as "monomer (b1)") and constituent units derived from amino group-containing monomer (b2) (hereinafter also referred to as "monomer (b2)") is 0.05% by mass or less, the acid value is 1.0 mgKOH / g or less, Mw is greater than 250,000, and Mw is smaller than that of acrylic polymer (A). Since this composition contains polymer (B), even when the adhesive layer obtained from this composition is used in contact with an adherend that experiences significant shrinkage due to temperature changes (e.g., a polarizing plate), it is possible to easily form an adhesive layer that can generate sufficient shear stress against the shrinkage of the adherend while relieving internal stress without leaving any residual stress.

[0052] The total content of constituent units derived from monomer (b1) and monomer (b2) in polymer (B) is 0.05% by mass or less, preferably 0.02% by mass or less, and more preferably 0.01% by mass or less, based on 100% by mass of all constituent units of polymer (B). The lower limit of this total content is preferably 0% by mass. When the total content is within the aforementioned range, the resulting adhesive layer has a low crosslinking density, exhibiting excellent stress relaxation properties and easily forming an adhesive layer that is less prone to peeling of the adherend. In particular, when the content is within the aforementioned range, if the adhesive layer is used in contact with an adherend that can shrink significantly (e.g., a polarizing plate), the stress on the adhesive layer can be relaxed, and furthermore, the shrinkage of the adherend can be suppressed. The content of constituent units derived from monomer (b1) and monomer (b2) can be calculated from the amounts of monomer (b1) and monomer (b2) in the monomer components used when synthesizing polymer (B).

[0053] Examples of monomers (b1) and monomer (b2) include monomers similar to monomer (a1) and monomer (a2), respectively. Monomer (b1) may be used alone or in combination of two or more types. Monomer (b2) may also be used alone or in combination of two or more types. Monomer (b2) is a monomer other than monomer (b1).

[0054] [Monomer (b3)] Polymer (B) preferably contains structural units derived from at least one monomer (b3) selected from alkyl (meth)acrylates and alkoxyalkyl (meth)acrylates (hereinafter also referred to as "monomer (b3)"), and is particularly preferably containing structural units derived from alkyl (meth)acrylates and alkoxyalkyl (meth)acrylates. By including alkyl (meth)acrylate-derived structural units in polymer (B), the tackiness and reworkability of the resulting adhesive layer can be easily adjusted. Furthermore, because polymer (B) contains structural units derived from alkoxyalkyl (meth)acrylate, an adhesive layer with excellent aging properties and quality stability can be formed productively.

[0055] When polymer (B) contains constituent units derived from monomer (b3), the content of constituent units derived from monomer (b3) is preferably 25 to 100% by mass, more preferably 50 to 100% by mass, relative to 100% by mass of all constituent units of polymer (B), in order to better exhibit the above-mentioned effects. When polymer (B) contains constituent units other than those derived from monomer (b1), monomer (b2), and monomer (b3), in particular when it contains constituent units derived from monomer (b1), monomer (b2), monomer (b3), and monomer (b4) described below, the upper limit of the content of constituent units derived from monomer (b3) is preferably 98% by mass or less, more preferably 97% by mass or less, and the lower limit is preferably 25% by mass or more, more preferably 50% by mass or more. The content of constituent units derived from monomer (b3) can be calculated from the amount of monomer (b3) in the monomer components used when synthesizing polymer (B).

[0056] Examples of monomer (b3) include monomers similar to monomer (a3). Monomer (b3) may be used alone or in combination of two or more types. Monomer (b3) is a monomer other than monomer (b1), monomer (b2), and monomer (b4) described below.

[0057] [Alicyclic hydrocarbon group-containing (meth)acrylates and aromatic hydrocarbon group-containing (meth)acrylates] The polymer (B) may further contain constituent units derived from at least one monomer (b4) (hereinafter also referred to as "monomer (b4)") selected from alicyclic hydrocarbon group-containing (meth)acrylates and aromatic hydrocarbon group-containing (meth)acrylates. By including structural units derived from alicyclic hydrocarbon group-containing (meth)acrylate in polymer (B), the cohesive force and stress relaxation properties of the resulting adhesive layer can be easily adjusted. Furthermore, because polymer (B) contains structural units derived from aromatic hydrocarbon group-containing (meth)acrylate, it is possible to easily form an adhesive layer that exhibits superior adhesion to the adherend and suppresses light leakage.

[0058] When polymer (B) contains constituent units derived from monomer (b4), the content of monomer (b4)-derived constituent units is preferably 1 to 50% by mass, more preferably 1 to 30% by mass, relative to 100% by mass of the total constituent units of polymer (B), in order to better exhibit the above-mentioned effects. The content of constituent units derived from monomer (b4) can be calculated from the amount of monomer (b4) in the monomer components used when synthesizing polymer (B).

[0059] Examples of monomer (b4) include monomers similar to monomer (a4). Monomer (b4) may be used alone or in combination of two or more types. Monomer (b4) is a monomer other than monomer (b1) and monomer (b2).

[0060] [Other monomers] Polymer (B) may further contain other monomer-derived constituent units other than monomers (b1), (b2), (b3), and (b4), to the extent that it does not impair the purpose of the present invention. The content of the aforementioned other monomer-derived constituent units is preferably 30% by mass or less, and more preferably 20% by mass or less, relative to 100% by mass of the total constituent units of polymer (B), in order to better exhibit the aforementioned effects. The content of constituent units derived from other monomers can be calculated from the amount of other monomers in the monomer components used when synthesizing polymer (B).

[0061] Examples of the other monomers mentioned above include those similar to the other monomers listed in the section for polymer (A). These other monomers may be used individually or in combination of two or more.

[0062] [Method for synthesizing polymer (B)] Polymer (B) can be synthesized by polymerizing the aforementioned monomer components, and may be a random polymer, block polymer, or graft polymer, and can be synthesized by various polymerization methods. The polymerization method is not particularly limited, but examples include solution polymerization, emulsion polymerization, and suspension polymerization. Among these, when producing the present composition using a mixture of polymers obtained by polymerization, polymerization by solution polymerization is preferred from the viewpoint that the processing steps are relatively simple and can be carried out in a short time.

[0063] A specific example of solution polymerization involves placing monomer components, polymerization initiators, and other components such as chain transfer agents and polymerization solvents in a reaction vessel, setting the reaction start temperature to typically 40°C or higher, preferably 50°C or higher, typically 100°C or lower, and preferably 80°C or lower, and maintaining the reaction system at a temperature of typically 50-90°C, preferably 60-90°C, for 2-20 hours. The reaction is carried out, for example, under an inert gas atmosphere such as nitrogen gas. In addition, at least one selected from monomer components, polymerization initiators, chain transfer agents, and polymerization solvents may be added during the polymerization reaction.

[0064] Polymerization initiators and polymerization solvents that may be used in the synthesis of polymer (B) include the same polymerization initiators and polymerization solvents as those described in the section on the synthesis method of polymer (A).

[0065] [Properties of polymer (B)] The Mw of polymer (B), as measured by the GPC method, is greater than 250,000 and less than the Mw of polymer (A). The lower limit of the Mw of polymer (B) is preferably 300,000 or more, more preferably 500,000 or more. The upper limit of the Mw of polymer (B) is not particularly limited as long as it is less than the Mw of polymer (A), but is preferably 1,000,000 or less. When Mw is within the aforementioned range, even when the adhesive layer obtained from this composition is used in contact with an adherend that experiences significant shrinkage due to temperature changes (e.g., a polarizing plate), it is possible to easily form an adhesive layer that can generate sufficient shear stress in response to the shrinkage of the adherend while relieving internal stress without leaving any residual stress. The Mw can be measured specifically by the method described in the following examples.

[0066] The Mw of polymer (B) is smaller than the Mw of polymer (A), and the ratio of the Mw of polymer (B) to the Mw of polymer (A) (Mw of polymer (B) / Mw of polymer (A)) is preferably 0.8 or less, more preferably 0.6 or less. By having the relationship between the Mw of polymers (A) and (B) within the aforementioned range, an adhesive layer with a good balance of cohesive force and stress relaxation properties can be easily formed.

[0067] The acid value of polymer (B) is 1.0 mgKOH / g or less, preferably 0.8 mgKOH / g or less, and more preferably 0 mgKOH / g. When the acid value of polymer (B) is within the above range, corrosion of the adherend in contact with the adhesive layer formed from the resulting adhesive composition can be suppressed. The acid value can be measured specifically by the method described in the following examples.

[0068] A polymer (B) having an acid value within the aforementioned range can be synthesized, for example, by using an acid group-containing monomer at a rate of 0.12% by mass or less per 100% by mass of the monomer component, or, more preferably, by substantially omitting the use of acid group-containing monomers during the synthesis of polymer (B). Examples of the acidic group-containing monomer include those similar to the acidic group-containing monomers listed in the Polymer (A) column.

[0069] [Polymer (B) content] This composition may contain one or more polymers (B). The content of polymer (B) in this composition is 10 parts by mass or more, preferably 25 parts by mass or more, more preferably 40 parts by mass or more, preferably 300 parts by mass or less, and more preferably 200 parts by mass or less, per 100 parts by mass of polymer (A). When the polymer (B) content is within the above range, even when the adhesive layer obtained from this composition is used in contact with an adherend that experiences significant shrinkage due to temperature changes (e.g., a polarizing plate), it is possible to easily form an adhesive layer that can generate sufficient shear stress in response to the shrinkage of the adherend while relieving internal stress without leaving any residual stress.

[0070] <Isocyanate-based curing agent (C)> This composition contains an isocyanate-based curing agent (C) (hereinafter also referred to as "curing agent (C)"). Examples of curing agent (C) include isocyanate compounds having two or more isocyanate groups in one molecule.

[0071] Examples of curing agents (C) include isocyanate monomers such as xylylene diisocyanate, tolylene diisocyanate, chlorophenyl diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and hydrogenated diphenylmethane diisocyanate; isocyanate compounds obtained by addition reaction of isocyanate monomers with divalent or higher alcohol compounds such as trimethylolpropane; burette-type isocyanate compounds; urethane prepolymer-type isocyanates obtained by addition reaction of isocyanate monomers with polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, etc.; and isocyanurate compounds.

[0072] [Hardening agent (C) content] This composition may contain one or more curing agents (C). The content of the curing agent (C) in this composition is more than 6 parts by mass and less than 30 parts by mass, preferably 7 parts by mass or more, more preferably 8 parts by mass or more, preferably 25 parts by mass or less, and more preferably 20 parts by mass or less, based on 100 parts by mass of the total of polymer (A) and polymer (B). The fact that the content of curing agent (C) is within the aforementioned range means that curing agent (C) is used in an amount such that the amount of isocyanate groups is in excess of the number of crosslinkable functional groups of polymer (A). When curing agent (C) is used in such an amount, self-condensates of curing agent (C) that did not contribute to the crosslinking reaction with polymer (A) are formed, and it is thought that these condensates become entangled with polymer (A) and / or (B), thereby easily forming an adhesive layer with higher cohesive force compared to an adhesive layer formed from a conventional adhesive composition.

[0073] <Other ingredients> The composition may contain other components besides the polymer (A), polymer (B), and curing agent (C), such as a curing agent other than curing agent (C) (D), a silane coupling agent (E), an antistatic agent (F), a tackifying resin, an antioxidant, a light stabilizer, a metal corrosion inhibitor, a plasticizer, a crosslinking accelerator, a surfactant, a reworking agent, or an organic solvent, as long as the effects of the present invention are not impaired. These other components may be used individually or in combination of two or more.

[0074] [Hardening agents other than hardening agent (C) (D)] This composition may also contain a curing agent (D) other than curing agent (C) (hereinafter also referred to as "curing agent (D)"). Examples of the curing agent (D) include epoxy-based curing agents and metal chelate-based curing agents.

[0075] By using the curing agent (C) and curing agent (D) in combination, various properties of the composition can be improved. In particular, by using curing agent (C) in combination with an epoxy curing agent, an adhesive layer with superior moisture and heat resistance and aging properties can be easily formed, and by using curing agent (C) in combination with a metal chelating curing agent, an adhesive layer with superior aging properties can be easily formed.

[0076] Examples of epoxy curing agents include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, N,N,N',N'-tetraglycidylaminophenylmethane, triglycidyl isocyanurate, mN,N-diglycidylaminophenyl glycidyl ether, N,N-diglycidyltoluidine, N,N-diglycidylaniline, pentaerythritol polyglycidyl ether, and 1,6-hexanediol diglycidyl ether.

[0077] Examples of metal chelating curing agents include compounds in which alkoxides, acetylacetone, ethyl acetoacetate, etc., are coordinated to polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. Specific examples include aluminum isopropylate, aluminum secondary butyrate, aluminum ethyl acetoacetate / diisopropylate, aluminum trisethyl acetoacetate, and aluminum trisacetylacetonate.

[0078] If the composition contains a curing agent (D), the amount of curing agent (D) in the composition is preferably 0.005 parts by mass or more, more preferably 0.01 parts by mass or more, preferably 6 parts by mass or less, and more preferably 3 parts by mass or less, based on 100 parts by mass of the total of polymer (A) and polymer (B), in order to better exhibit the above-mentioned effects.

[0079] [Silane coupling agent (E)] This composition may also contain a silane coupling agent (E). The inclusion of a silane coupling agent (E) in this composition allows for the easy formation of an adhesive layer with high adhesion to the adherend.

[0080] Examples of silane coupling agents (E) include polymerizable unsaturated group-containing silane coupling agents such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane; epoxy group-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino group-containing silane coupling agents such as 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane; and halogen-containing silane coupling agents such as 3-chloropropyltrimethoxysilane. Among these, epoxy group-containing silane coupling agents are preferred because they can easily form an adhesive layer with excellent stress relaxation properties.

[0081] If the composition contains a silane coupling agent (E), the amount of silane coupling agent (E) in the composition is usually 1 part by mass or less, preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, preferably 1 part by mass or less, and more preferably 0.5 parts by mass or less, per 100 parts by mass of the total of polymer (A) and polymer (B). When the content of the silane coupling agent (E) is within the aforementioned range, peeling of the adhesive layer from the adherend can be easily suppressed even in a high-humidity, high-temperature environment, and an adhesive layer in which bleeding of the silane coupling agent (E) is less likely to occur can be easily formed even in a high-temperature environment.

[0082] [Antistatic agent (F)] This composition may contain an antistatic agent (F). Examples of antistatic agents (F) include surfactants, ionic compounds, and conductive polymers.

[0083] Examples of surfactants include cationic surfactants having cationic groups such as quaternary ammonium salts, quaternary ammonium amide salts, pyridium salts, and primary to tertiary amino groups; anionic surfactants having anionic groups such as sulfonic acid bases, sulfate ester bases, and phosphate ester bases; amphoteric surfactants such as alkyl betaines, alkylimidazolinium betaines, alkylamine oxides, and amino acid sulfate esters; and nonionic surfactants such as glycerin fatty acid esters, sorbitan fatty acid esters, polyoxyethylene alkylamines, polyoxyethylene alkylamine fatty acid esters, N-hydroxyethyl-N-2-hydroxyalkylamines, and alkyldiethanolamides.

[0084] Furthermore, examples of surfactants include reactive emulsifiers having polymerizable groups, and polymer-based surfactants can also be used in which the aforementioned surfactant or monomer components containing a reactive emulsifier have been increased in molecular weight.

[0085] Ionic compounds are compounds composed of a cation and an anion, and may be solid or liquid compounds at room temperature (23°C) and 50% RH.

[0086] The cation portion constituting the ionic compound may be either an inorganic cation or an organic cation, or both. Preferably, alkali metal ions and alkaline earth metal ions are used as inorganic cations, and Li is preferred due to its excellent antistatic properties. + na + and K +is more preferable. Examples of the organic cation include pyridinium cation, piperidinium cation, pyrrolidinium cation, pyrroline cation, pyrrole cation, imidazolium cation, tetrahydropyrimidinium cation, dihydropyrimidinium cation, pyrazolium cation, pyrazolinium cation, tetraalkylammonium cation, trialkylalkoxyammonium cation, trialkylsulfonium cation, tetraalkylphosphonium cation and derivatives thereof.

[0087] The anion part constituting the ionic compound is not particularly limited as long as it can form an ionic bond with the cation part to form an ionic compound. Specifically, for example, F - , Cl - , Br - , I - , AlCl4 - , Al2Cl7 - , BF4 - , PF6 - , SCN - , ClO4 - , NO3 - , CH3COO - , CF3COO - , CH3SO3 - , CF3SO3 - , (CF3SO2)2N - , (FSO2)2N - , (CF3SO2)3C - , AsF6 - , SbF6 - , NbF6 - , TaF6 - , F(HF) n - (n is 1 to 3), (CN)2N - , C4F9SO3 - , (C2F5SO2)2N - , C3F7COO - and (CF3SO2)(CF3CO)N - are mentioned.

[0088] Ionic compounds include lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium tris(trifluoromethanesulfonyl)methane, potassium bis(trifluoromethanesulfonyl)imide, potassium bis(fluorosulfonyl)imide, 1-ethylpyridinium hexafluorophosphate, 1-butylpyridinium hexafluorophosphate, 1-hexyl-4-methylpyridinium hexafluorophosphate, and 1-octyl-4-methylpyridinium hexafluorophosphate. Preferably, 1-octyl-4-methylpyridinium bis(fluorosulfonyl)imide, 1-octyl-4-methylpyridinium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium tetrafluoroborate, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, 1-octylpyridinium fluorosulfoniumimide, and 1-octyl-3-methylpyridinium trifluorosulfoniumimide are used.

[0089] Examples of conductive polymers include polythiophene, polyaniline, polypyrrole, and their derivatives.

[0090] If the composition contains an antistatic agent (F), the amount of antistatic agent (F) in the composition is usually 3 parts by mass or less, preferably 0.01 to 3 parts by mass, and more preferably 0.05 to 2.5 parts by mass, per 100 parts by mass of the total of polymer (A) and polymer (B).

[0091] [organic solvent] This composition may contain organic solvents, as long as they do not impair the effects of the present invention. Examples of organic solvents include the polymerization solvents described in the section on the synthesis method of polymer (A). This composition may also be prepared, for example, by mixing a polymer solution containing polymer (A) and polymerization solvent, a polymer solution containing polymer (B) and polymerization solvent, and a curing agent (C). The organic solvent content in this composition is, for example, 0% by mass or more, preferably 10% by mass or more, and for example, 90% by mass or less, preferably 80% by mass or less.

[0092] <Method for producing this composition> This composition can be produced, for example, by mixing polymer (A), polymer (B), curing agent (C), and other components as needed, using a known method with a stirring device or the like. When mixing and stirring each component, they may be mixed and stirred all at once, or they may be mixed and stirred sequentially. While there are no particular restrictions on stirring conditions, for ease of work and productivity, stirring at room temperature for approximately 10 to 120 minutes is acceptable.

[0093] <Uses of this composition> The use of this composition is not particularly limited and can be used in any application where adhesive layers have been used. However, in order to better demonstrate the effects of the present invention, this composition is preferably used for bonding optical components, and more preferably for bonding components constituting display devices such as touch panel input / output devices. Examples of components (adheres) to be bonded using this composition include optical films such as polarizing films (including elliptical polarizing films), phase difference films, anti-reflective films, brightness-enhancing films, light-diffusing films, and hard coat films; metal or metal oxide layers such as ITO layers; and glass or resin substrates.

[0094] Adhesive Sheet An adhesive sheet according to one embodiment of the present invention (hereinafter also referred to as "this adhesive sheet") has an adhesive layer obtained from this composition (hereinafter also referred to as "this adhesive layer"). The adhesive sheet may consist solely of the adhesive layer, or it may be a laminate comprising the adhesive layer and at least one adherend selected from the optical film, metal or metal oxide layer, and substrate, etc. For example, the adhesive layer contained in the laminate may be one layer or two or more layers. If there are two or more layers, they may be the same layer or different layers. The same applies to the adherend (other layers such as optical films) contained in the laminate.

[0095] The thickness of this adhesive sheet is not particularly limited. If this adhesive sheet consists only of this adhesive layer, its thickness is approximately the same as the thickness of this adhesive layer described below. When the adhesive sheet is the laminate described above, the thickness varies depending on the type of substrate and can be appropriately selected according to the application, but for example it is 5 μm or more, preferably 10 μm or more, and for example it is 300 μm or less, preferably 200 μm or less.

[0096] <This adhesive layer> This adhesive layer is formed from this composition, and specifically, it can be formed by crosslinking this composition. As described above, a preferred embodiment of the adhesive layer obtained by crosslinking the composition includes an embodiment that includes a crosslinked polymer (A) with a curing agent (C), and further, an embodiment in which the self-condensates of excess curing agent (C) that did not contribute to the crosslinking reaction are intertwined with at least one selected from polymer (A), the crosslinked polymer (A), and polymer (B).

[0097] When crosslinking this composition to form the adhesive layer, the gel fraction of the adhesive layer is not particularly limited, but is preferably 50% or more, more preferably 60% or more, preferably 90% or less, and more preferably 85% or less, from the viewpoint that an adhesive layer with excellent flexibility can be easily formed. The gel fraction can be measured specifically by the method described in the following examples.

[0098] The thickness of the adhesive layer can be set appropriately according to the application of the adhesive sheet, and is not particularly limited, but is usually 5 μm or more, preferably 10 μm or more, and usually 125 μm or less, preferably 100 μm or less.

[0099] The adhesive strength of this adhesive layer is preferably 1.0 N / 25 mm or more, in terms of being able to adhere sufficiently to the substrate, and more preferably 2.0 to 20.0 N / 25 mm, in terms of having an appropriate adhesive strength that prevents peeling or lifting from the substrate when used in adhesion, and allows for removal from the substrate without leaving any adhesive residue when desired. The adhesive strength can be measured specifically by the method described in the following examples.

[0100] [Method for manufacturing this adhesive sheet] The adhesive layer can be formed on the adherend or support by, for example, applying the composition to the adherend or support and causing a crosslinking reaction of the applied composition. After applying the composition to the adherend or support, the adherend or support may be placed on the applied surface as needed to cause a crosslinking reaction of the composition.

[0101] To form an adhesive sheet consisting solely of this adhesive layer, the adhesive layer can be peeled off the support. When storing or transporting the adhesive sheet consisting solely of this adhesive layer, it can be stored and transported together with the support, and when using it, it can be peeled off the support and used as an adhesive sheet consisting solely of the adhesive layer. Examples of such support materials include substrates that have undergone a delamination process.

[0102] If the adhesive sheet is a laminate, for example, by applying the composition onto the adherend and then placing a support on the coated surface, a laminate can be obtained in which the adherend, the adhesive layer, and the support are laminated in that order. When in use, the support can be peeled off and the laminate can be used as an adhesive sheet consisting of the adherend and the adhesive layer.

[0103] The substrate used as the adherend or the substrate used as the support is not particularly limited, but examples include resin plates, glass plates, woven fabrics, nonwoven fabrics, paper, and the like. The resin is preferably a transparent resin, and examples of such transparent resins include polycarbonate (PC), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polypropylene (PP), acrylonitrile-butadiene-styrene copolymer (ABS), and polyamide (nylon).

[0104] Methods for applying this composition include known methods such as spin coating, knife coating, roll coating, bar coating, blade coating, die coating, and gravure coating, which apply the adhesive layer to a predetermined thickness. In some cases, instead of coating, the composition can be placed on the substrate or support by immersing it in the composition.

[0105] After applying (placing) the composition onto an adherend or support, the applied (placing) composition may be dried as needed. The drying conditions vary depending on the type of solvent, but typically include drying at 50°C or higher, preferably 60°C or higher, typically 150°C or lower, preferably 100°C or lower, for typically 1 minute or more, preferably 2 minutes or more, typically 10 minutes or less, preferably 7 minutes or less.

[0106] As described above, it is preferable to include a step of curing the composition after drying it as necessary. Suitable curing conditions include curing in an environment of 5°C or higher, preferably 15°C or higher, usually 60°C or lower, preferably 40°C or lower, usually 5-70% RH, preferably 5-50% RH, for 3 days or more, preferably 7 days or more, and preferably 10 days or less. Curing under such conditions allows for sufficient crosslinking and facilitates the formation of an adhesive layer with stable physical properties.

[0107] Optical Components An optical component according to one embodiment of the present invention has this adhesive layer. A specific example of the optical component is the laminated body.

[0108] More specifically, examples of the optical components include a liquid crystal display device comprising a laminate in which a polarizing plate, the adhesive layer, a liquid crystal panel, the adhesive layer, and a polarizing plate are stacked in that order, and a touch panel comprising a laminate in which a shatterproof film, the adhesive layer, an ITO layer, and a glass panel are stacked in that order. [Examples]

[0109] One embodiment of the present invention will be described in more detail below based on the examples, but the present invention is not limited to these examples.

[0110] <Weight average molecular weight (Mw)> The weight-average molecular weight (Mw) of each polymer was analyzed by gel permeation chromatography (GPC) and calculated on a polystyrene basis under the following conditions. • Equipment: GPC-8220 (manufactured by Tosoh Corporation) • Column: TSKgel G7000H XL / 7.8mm ID x 1 + TSKgel GMH XL / 7.8mm ID x 2 + TSKgel G2500H XL 7.8mm ID x 1 (both manufactured by Tosoh Corporation) • Medium: Tetrahydrofuran ·Flow rate: 1.0mL / min ·Concentration: 1.5mg / mL ·Injection volume: 300μL Column temperature: 40°C

[0111] <Acid value> The acid value (mgKOH / g) of each polymer refers to the amount of potassium hydroxide (mg) required to neutralize 1g of the polymer. The measurement method was as follows: First, approximately 1 g of polymer was dissolved in 50 mL of a toluene / ethanol (volume ratio: 2 / 1) mixture to prepare the measurement sample. Next, the measurement sample was subjected to potentiometric titration with a 0.1 N potassium hydroxide ethanol solution using an automatic titrator (Toa DKK Co., Ltd., AUT-501) to determine the amount of potassium hydroxide ethanol solution required to neutralize the measurement sample. The acid value was calculated using the following formula (I). Formula (I): Acid value (mgKOH / g)=(B×f×5.611) / S B: Volume (mL) of 0.1N potassium hydroxide ethanol solution used for titration. f: Factor of 0.1N potassium hydroxide ethanol solution S: Mass of solid content in the sample (g)

[0112] [Manufacturing example A-1] In a reaction apparatus equipped with a stirrer, reflux condenser, thermometer, and nitrogen inlet tube, 99.9 parts by mass of n-butyl acrylate (BA), 0.1 parts by mass of 4-hydroxybutyl acrylate (4HBA), and 100 parts by mass of ethyl acetate were charged, and the temperature was raised to 70°C while introducing nitrogen gas. Next, 0.05 parts by mass of 2,2'-azobisisobutyronitrile (hereinafter also referred to as "AIBN") was added, and the polymerization reaction was carried out under a nitrogen atmosphere at 75-76°C for 4 hours to synthesize an acrylic polymer (A-1). After the reaction was complete, the reaction solution was diluted with ethyl acetate to prepare a polymer solution. The Mw of the obtained acrylic polymer (A-1) was 1.5 million.

[0113] [Manufacturing example B-1] In a reaction apparatus equipped with a stirrer, reflux condenser, thermometer, and nitrogen inlet tube, 100 parts by mass of BA and 100 parts by mass of ethyl acetate were charged, and the temperature was raised to 70°C while introducing nitrogen gas. Next, 0.1 parts by mass of AIBN was added, and the polymerization reaction was carried out under a nitrogen atmosphere at 75-76°C for 4 hours. After the reaction was complete, the reaction solution was diluted with ethyl acetate to prepare a polymer solution. The Mw of the obtained acrylic polymer (B-1) was 700,000.

[0114] [Manufacturing examples A-3 to A-21, A-23, A-24, cA-1 to cA-3, cA-5, B-3 to B-19 and cB-1 to cB-3] Polymers (A-3) to (A-21), (A-23), (A-24), and polymers (cA-1) to (cA-3), (cA-5) were synthesized in the same manner as in Production Example A-1, except that the types and amounts of monomers used were changed as shown in Tables 1 to 3. Furthermore, polymers (B-3) to (B-19) and polymers (cB-1) to (cB-3) were synthesized in the same manner as in manufacturing example B-1. The Mw values ​​of each polymer obtained are shown in Tables 1-3. Note that the values ​​listed in the monomer column in Tables 1-3 represent parts by mass.

[0115] [Manufacturing example A-2] Polymer (A-2) was synthesized in the same manner as in Production Example A-1, except that the type and amount of monomers used were changed as shown in Table 1, and the amount of AIBN used was changed to 0.045 parts by mass. The Mw of the obtained polymer (A-2) was 2 million.

[0116] [Manufacturing example A-22] Polymer (A-22) was synthesized in the same manner as in Production Example A-1, except that the type and amount of monomers used were changed as shown in Table 2, and the amount of AIBN used was changed to 0.03 parts by mass. The Mw of the obtained polymer (A-22) was 2.6 million.

[0117] [Manufacturing example A-25] Polymer (A-25) was synthesized in the same manner as in Production Example A-1, except that the type and amount of monomers used were changed as shown in Table 2, and the amount of AIBN used was changed to 0.045 parts by mass. The Mw of the obtained polymer (A-25) was 1.8 million.

[0118] [Manufacturing example cA-4] Polymer (cA-4) was synthesized in the same manner as in Production Example A-1, except that the type and amount of monomers used were changed as shown in Table 3, and the amount of AIBN used was changed to 0.2 parts by mass. The Mw of the obtained polymer (cA-4) was 500,000.

[0119] [Manufacturing example B-2] Polymer (B-2) was synthesized in the same manner as in production example B-1, except that the type and amount of monomer used were changed as shown in Table 1, and the amount of AIBN used was changed to 0.4 parts by mass. The Mw of the obtained polymer (B-2) was 300,000.

[0120] [Manufacturing example B-20] Polymer (B-20) was synthesized in the same manner as in Production Example B-1, except that the type and amount of monomers used were changed as shown in Table 3, and the amount of AIBN used was changed to 0.2 parts by mass. The Mw of the obtained polymer (B-20) was 500,000.

[0121] [Manufacturing example B-21] Polymer (B-21) was synthesized in the same manner as in Production Example B-1, except that the type and amount of monomers used were changed as shown in Table 3, and the amount of AIBN used was changed to 0.05 parts by mass. The Mw of the obtained polymer (B-21) was 1.5 million.

[0122] [Manufacturing example cB-4] Polymer (cB-4) was synthesized in the same manner as in Production Example B-1, except that the type and amount of monomer used were changed as shown in Table 3, and the amount of AIBN used was changed to 0.5 parts by mass. The Mw of the obtained polymer (cB-4) was 200,000.

[0123] [Example 1] A polymer solution of polymer (A-1) obtained in Production Example A-1 was mixed with a polymer solution of polymer (B-1) obtained in Production Example B-1 to obtain a polymer mixture. The amount of polymer (B-1) added was 60 parts by mass of polymer (B-1) for every 100 parts by mass of polymer (A-1) in the polymer solution obtained in Production Example A-1. Next, an isocyanate-based curing agent L-45 (manufactured by Soken Chemical Co., Ltd.) was added to the obtained polymer mixture and mixed to obtain an adhesive composition. The amount of L-45 added was 12 parts by mass of solids of L-45 for every 100 parts by mass of the total of polymer (A-1) and polymer (B-1).

[0124] [Examples 2-36 and Comparative Examples 1-11] An adhesive composition was obtained in the same manner as in Example 1, except that the formulation was changed as shown in Tables 1 to 3. Note that the amounts added in Tables 1-3 [parts by mass] represent the amount of polymer (B) or the comparison polymer of polymer (B) added per 100 parts by mass of polymer (A) or the comparison polymer of polymer (A). Furthermore, the values ​​in the columns for each curing agent, silane coupling agent, and antistatic agent indicate the amount (in parts by mass) of solid content of each component added relative to 100 parts by mass of the total of polymer (A) (or a comparative polymer for polymer (A)) and polymer (B) (or a comparative polymer for polymer (B)).

[0125] [Evaluation of adhesive compositions] The obtained adhesive compositions were evaluated using the following method. The evaluation results are shown in Tables 1-3.

[0126] [Fabrication of laminates] The adhesive compositions obtained in the examples and comparative examples were applied to a release-treated PET film and dried at 90°C for 4 minutes to form an adhesive layer with a thickness of 20 μm after drying. Next, another release-treated PET film was laminated onto the formed adhesive layer to create a laminate having an adhesive layer sandwiched between two PET films.

[0127] [Fabrication of polarizing plates with adhesive layer] The adhesive compositions obtained in the examples and comparative examples were applied to a release-treated PET film and dried at 90°C for 4 minutes to form an adhesive layer with a thickness of 20 μm after drying. Next, a polarizing plate was placed on top of the formed adhesive layer and bonded together, and cured for 7 days in an environment of 23°C / 50%RH to produce a polarizing plate with an adhesive layer having a PET film.

[0128] [Preparation of samples for evaluating high-temperature durability, moist heat durability, and reworkability] The prepared polarizing plate with adhesive layer was cut to 150 mm x 250 mm, the PET film was peeled off, and it was attached to a 1.1 mm thick glass plate and pressed down. The glass plate with the adhesive-layered polarizing plate attached was autoclaved at 50°C and 5 atm for 20 minutes, and then left in an environment of 23°C / 50% RH for 24 hours to prepare an evaluation sample.

[0129] <Gel fraction> The laminate prepared as described above was cured for 7 days at 23°C / 50%RH. After curing, 0.1 g (dry mass (1)) of the adhesive layer of the laminate was taken into a sample bottle, 30 g of ethyl acetate was added to the sample bottle, and it was left at 23°C for 24 hours. Subsequently, the contents of the sample bottle were filtered through a 200-mesh stainless steel mesh, and the residue on the mesh was dried at 100°C for 2 hours to obtain the dry mass (dry mass (2)), and the gel fraction was determined by the following formula. Gel fraction (%) = (dry mass (2) / dry mass (1)) × 100

[0130] <Aging properties> The laminate prepared as described above was placed in an environment of 23°C / 50%RH, and the gel fraction of the laminate was measured over time. The time at which the difference between the gel fraction after X hours and the gel fraction after X+24 hours became less than 1% was confirmed and evaluated according to the following criteria. (Evaluation Criteria) ◎: The aforementioned time X is less than 168 hours. ○: The aforementioned time X is 168 hours or more. In Table 3, a "-" indicates that the aging properties were not evaluated because the adhesive composition did not harden.

[0131] <High temperature durability (115℃)> The evaluation samples prepared as described above were left at 115°C for 500 hours. Afterward, they were removed and left at 23°C / 50%RH for 24 hours, and their appearance was visually evaluated according to the following criteria. (Evaluation Criteria) ◎: No defects such as foaming or floating. △: Slight foaming and floating may occur, which could potentially cause practical problems. ×: Significant foaming, lifting, and peeling have occurred.

[0132] <Heat and moisture resistance (65℃ / 95%RH)> The evaluation samples prepared as described above were left in an environment of 65°C / 95%RH for 500 hours. Afterward, they were removed and left in an environment of 23°C / 50%RH for 24 hours, and their appearance was visually evaluated according to the following criteria. (Evaluation Criteria) ◎: No defects such as foaming. ○: Minor foaming is occurring, but it is not at a level that poses any practical problems. △: Defects such as foaming have occurred, which may cause practical problems. ×: Significant foaming is occurring.

[0133] <Reworkability> As described above, the polarizing plates with adhesive layers were peeled off by hand from the prepared evaluation samples, and the degree of contamination and peelability of the glass plate surface were evaluated. (Evaluation Criteria) ◎: It can be easily peeled off and does not contaminate the glass plate surface. ○: Slightly difficult to peel off, but there is no contamination on the glass plate surface. △: Somewhat difficult to peel off, slight contamination (adhesive residue) can be seen on the surface of the glass plate. ×: Difficult to remove, and obvious contamination (adhesive residue) is visible on the glass surface.

[0134] <Light leakage test> As described above, a polarizing plate with an adhesive layer containing a PET film was cut to 150 mm x 250 mm, the PET film was peeled off, and a laminate for light leakage testing was prepared by attaching and pressing it to both sides of a 1.1 mm thick glass plate so that the polarization axes were perpendicular to each other. The prepared laminate for light leakage testing was autoclaved at 50°C and 5 atmospheres for 20 minutes, and then left in an environment of 80°C for 500 hours. The obtained laminate for light leakage testing was irradiated with light from the backlight of a liquid crystal monitor, and the light leakage was visually evaluated according to the following criteria. (Evaluation Criteria) ◎: No light leakage is observed. ○: A slight light leak is visible, but it does not pose any practical problems. △: Light leakage is observed, which may cause practical problems. ×: Significant light leakage is observed.

[0135] <Adhesion Test> As described above, the polarizing plate with an adhesive layer having a PET film was cut to a width of 25 mm, the release-treated PET film was peeled off, and it was bonded to a glass plate in an environment of 23°C / 50% RH. The plate was then autoclaved for 20 minutes under conditions of 50°C and 5 atmospheres. After that, it was removed to an environment of 23°C / 50% RH and left to stand for 1 hour. The adhesive strength was measured when the polarizing plate with the adhesive layer was peeled from the glass plate at a peeling angle of 180° and a tensile speed of 300 mm / min.

[0136] <Corrosive> As described above, the PET film was peeled off the polarizing plate with an adhesive layer, and a 10mm x 60mm cut ITO vapor-deposited film was bonded onto the adhesive layer. The plate was then autoclaved at 50°C and 5 atmospheres for 20 minutes. Next, it was left for 1 hour at 23°C / 50%RH, and then for 500 hours at 60°C / 90%RH. After leaving it for 1 hour at 23°C / 50%RH, the resistance value of the ITO vapor-deposited film (resistance value after the test) was measured. This was compared with the resistance value of the ITO vapor-deposited film before bonding to the adhesive layer (resistance value before the test), which had been measured in advance. The rate of change in the resistance value after the test relative to the resistance value before the test was determined and evaluated according to the following criteria. Here, since the change in resistance value is thought to be caused by the corrosion of ITO, a rate of change exceeding 120% was judged to indicate ITO corrosion, and a rate of change of 120% or less was judged to indicate no ITO corrosion. A tester (Sanwa Electric Instrument Co., Ltd., digital multimeter PC510) was used to measure the resistance value. (Evaluation Criteria) ◎: The rate of change (resistance value after test × 100 / resistance value before test) is 120% or less. ×: The rate of change (resistance value after test × 100 / resistance value before test) exceeds 120%.

[0137] [Table 1]

[0138] [Table 2]

[0139] [Table 3]

[0140] The meanings of the symbols for each component in Tables 1-3 are as follows: • BA: n-butyl acrylate • 2EHA: 2-Ethylhexyl acrylate • MA: Methyl acrylate MEA: 2-methoxyethyl acrylate • LA: Lauryl acrylate IBXA: Isobornyl acrylate BzA: Benzyl acrylate • AM: Acrylamide • NVP: N-vinylpyrrolidone • 4HBA: 4-hydroxybutyl acrylate • 2HEA: 2-hydroxyethyl acrylate AA: Acrylic acid • 2EHMA:2-Ethylhexyl methacrylate • DMA: Dimethylaminoethyl acrylate • L-45: Trimethylolpropane adduct of tolylene diisocyanate (manufactured by Soken Chemical Co., Ltd.) • Y-75: Isocyanurate derivative of hexamethylene diisocyanate (manufactured by Soken Chemical Co., Ltd.) • TD-75: Trimethylolpropane adduct of xylylene diisocyanate (manufactured by Soken Chemical Co., Ltd.) • E-5CM: Epoxy-based hardener (manufactured by Soken Chemical Co., Ltd.) • M-12AT: Aluminum chelate hardening agent (manufactured by Soken Chemical Co., Ltd.) • A-50: Silane coupling agent (manufactured by Soken Chemical Co., Ltd.) • AS-B: Antistatic agent (manufactured by Soken Chemical Co., Ltd.)

[0141] As shown in Tables 1 and 2, the adhesive layers in each example exhibited appropriate adhesive strength and excellent durability and corrosion resistance in high-temperature and high-humidity environments. On the other hand, Comparative Examples 1 and 2, which used polymer (A) and polymer (B) with oxidation levels exceeding 1.0 mg KOH / g, exhibited insufficient high-temperature durability, moist heat durability, and corrosion resistance. Comparative Examples 3 and 4, which used polymer (B) containing more than 0.05% by mass of constituent units derived from hydroxyl group-containing monomers or amino group-containing monomers as constituent components, exhibited insufficient high-temperature durability and moist heat durability. Comparative Examples 5 and 6, which used polymer (A) containing more than 0.4% by mass of constituent units derived from hydroxyl group-containing monomers as a constituent component, exhibited insufficient high-temperature durability and moist heat durability. Comparative Example 7, which used polymer (B) with an Mw of 250,000 or less, exhibited insufficient high-temperature durability and moist heat durability. Comparative Example 8, in which the content of polymer (B) was less than 10 parts by mass per 100 parts by mass of polymer (A), exhibited insufficient high-temperature durability and moist heat durability. Comparative Examples 9 and 10, in which the curing agent (C) content was 6 parts by mass or less or 30 parts by mass or more per 100 parts by mass of polymer (A) and polymer (B) combined, exhibited insufficient high-temperature durability and moist heat durability. Comparative Example 11, which used polymer (A) in which 0% by mass of constituent units derived from hydroxyl group-containing monomers and amino group-containing monomers were found to be a constituent component, exhibited insufficient high-temperature durability, moist heat durability, reworkability, and light leakage prevention performance.

Claims

1. An acrylic polymer (A) containing a total of more than 0% by mass and 0.4% by mass or less of constituent units derived from a hydroxyl group-containing monomer (a1) and an amino group-containing monomer (a2), having an acid value of 1.0 mgKOH / g or less, and having a weight-average molecular weight of 600,000 or more, An acrylic polymer (B) having a total content of constituent units derived from a hydroxyl group-containing monomer (b1) and constituent units derived from an amino group-containing monomer (b2) of 0.05% by mass or less, an acid value of 1.0 mgKOH / g or less, a weight-average molecular weight exceeding 250,000, and a weight-average molecular weight smaller than that of the acrylic polymer (A), Isocyanate-based curing agent (C) and Includes, The acrylic polymer (B) is contained in an amount of 10 parts by mass or more per 100 parts by mass of the acrylic polymer (A), The isocyanate-based curing agent (C) is contained in an amount exceeding 6 parts by mass but less than 30 parts by mass, with respect to a total of 100 parts by mass of the acrylic polymer (A) and acrylic polymer (B). The acrylic polymer (A) or acrylic polymer (B) contains constituent units derived from alkoxyalkyl (meth)acrylate, Adhesive composition.

2. The adhesive composition according to claim 1, wherein the acrylic polymer (A) contains 25 to 99.99% by mass of constituent units derived from at least one monomer (a3) ​​selected from alkyl (meth)acrylates and alkoxyalkyl (meth)acrylates.

3. The adhesive composition according to claim 1 or 2, wherein the acrylic polymer (B) contains 25 to 100% by mass of constituent units derived from at least one monomer (b3) selected from alkyl (meth)acrylate and alkoxyalkyl (meth)acrylate.

4. The adhesive composition according to any one of claims 1 to 3, wherein the acrylic polymer (A) contains a constituent unit derived from the hydroxyl group-containing monomer (a1) in an amount exceeding 0% by mass and not exceeding 0.4% by mass.

5. The adhesive composition according to any one of claims 1 to 4, wherein the acrylic polymer (A) contains 25 to 98% by mass of structural units derived from at least one monomer (a3) ​​selected from alkyl (meth)acrylate and alkoxyalkyl (meth)acrylate, and contains 1 to 50% by mass of structural units derived from at least one monomer (a4) selected from alicyclic hydrocarbon group-containing (meth)acrylate and aromatic hydrocarbon group-containing (meth)acrylate.

6. The adhesive composition according to any one of claims 1 to 5, wherein the acrylic polymer (B) contains 25 to 98% by mass of structural units derived from at least one monomer (b3) selected from alkyl (meth)acrylate and alkoxyalkyl (meth)acrylate, and contains 1 to 50% by mass of structural units derived from at least one monomer (b4) selected from alicyclic hydrocarbon group-containing (meth)acrylate and aromatic hydrocarbon group-containing (meth)acrylate.

7. The adhesive composition according to any one of claims 1 to 6, further comprising a curing agent (D) other than the isocyanate-based curing agent (C).

8. The adhesive composition according to any one of claims 1 to 7, further comprising a silane coupling agent (E).

9. The adhesive composition according to any one of claims 1 to 8, further comprising an antistatic agent (F).

10. An adhesive composition according to any one of claims 1 to 9, for use in optical components.

11. An adhesive sheet having an adhesive layer obtained from an adhesive composition according to any one of claims 1 to 10.

12. An optical member having an adhesive layer obtained from the adhesive composition according to any one of claims 1 to 10.

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