KR102628133B1 - Adhesive composition - Google Patents

Abstract

[Problem] To provide an adhesive composition capable of forming an adhesive layer showing excellent durability even under harsh durability conditions.
[Solution] In the adhesive composition containing a (meth)acrylic resin (A), a crosslinking agent (B), and a silane compound (C), the (meth)acrylic resin (A) has the following formula (a1) and the following formula ( It contains a structural unit derived from a hydroxyl group-containing (meth)acrylate represented by a2), and the crosslinking agent (B) is a tolylene diisocyanate-based compound and/or an adduct of a tolylene diisocyanate-based compound with a polyhydric alcohol compound. .

Description

Adhesive composition

The present invention relates to an adhesive composition useful for forming a highly durable adhesive layer in an optical film with an adhesive layer used in a liquid crystal display device, etc.

An optical film typified by a polarizing plate formed by laminating and bonding a transparent resin film to one or both sides of a polarizer is widely used as an optical member constituting an image display device such as a liquid crystal display device. Optical films such as polarizing plates are often used by bonding them to other members (such as liquid crystal cells in liquid crystal display devices) through an adhesive layer (see Patent Document 1). For this reason, as an optical film, an optical film equipped with an adhesive layer in which an adhesive layer is previously formed on one side is known.

Patent Document 1: Japanese Patent Publication No. 2010-229321

Recently, liquid crystal display devices have been deployed for use in mobile devices, such as smartphones and tablet-type terminals, and in-vehicle devices, such as car navigation systems. In these applications, there is a possibility of exposure to harsh environments compared to conventional indoor TV applications, so improving the durability of the device is an issue.

Durability is similarly required for optical films with adhesive layers that make up liquid crystal displays and the like. In other words, the adhesive layer in a liquid crystal display device, etc. may be placed under a high temperature or high temperature and high humidity environment, or an environment where high and low temperatures are repeated. In an optical film with an adhesive layer, the adhesive layer and the adhesive layer are bonded even under these environments. It is required to be able to suppress problems such as lifting or peeling at the interface with the optical member and foaming of the adhesive layer, and it is also required that the optical properties are not deteriorated. In particular, when the optical film is a polarizing plate, the adhesive layer is required to have higher durability than a general optical film due to strong shrinkage stress in a high temperature environment. The demand for improved durability of the above-described liquid crystal display devices has increased, and in recent years, the durability required for the adhesive layer has become very stringent.

Therefore, the purpose of the present invention is to provide an adhesive composition that can form an adhesive layer showing excellent durability even under such harsh durability conditions.

The present inventor has completed the present invention as a result of intensive studies to solve the above problems.

That is, the present invention includes the following.

[1] An adhesive composition containing a (meth)acrylic resin (A), a crosslinking agent (B), and a silane compound (C),

The (meth)acrylic resin (A) has the following formula (a1)

(In the formula, n represents an integer of ¹ to 4, A ¹ represents a hydrogen atom or an alkyl group, and good night)

A structural unit derived from a hydroxyl group-containing (meth)acrylate represented by and the following formula (a2)

(In the formula, m represents an integer of 5 or more, A ² represents a hydrogen atom or an alkyl group, X ² represents a methylene group which may have a substituent, and the substituents may be the same or different)

Contains a structural unit derived from a hydroxyl group-containing (meth)acrylate represented by,

The crosslinking agent (B) is an adhesive composition that is a tolylene diisocyanate-based compound and/or an adduct of a tolylene diisocyanate-based compound with a polyhydric alcohol compound.

[2] With respect to 100 parts by weight of all structural units constituting the (meth)acrylic resin, the ratio of structural units derived from the hydroxy group-containing (meth)acrylate represented by formula (a1) is 1.5 to 4.5 parts by weight, The pressure-sensitive adhesive composition according to [1], wherein the proportion of structural units derived from the hydroxyl group-containing (meth)acrylate represented by formula (a2) is 0.25 to 1.0 parts by weight.

[3] The (meth)acrylic resin is composed of structural units derived from alkyl acrylate (a3-1) whose homopolymer glass transition temperature is less than 0°C, and alkyl acrylate (a3-) whose homopolymer glass transition temperature is 0°C or higher. 2) The adhesive composition according to [1] or [2], which contains a structural unit derived from alkyl acrylate (a3) containing a structural unit derived from the alkyl acrylate (a3).

[4] Ratio of structural units derived from alkyl acrylate (a3-1) with a homopolymer glass transition temperature of less than 0°C and structural units derived from alkyl acrylate (a3-2) with a homopolymer glass transition temperature of 0°C or higher. (Weight ratio) is (a3-1)/(a3-2)=20/80 to 95/5, the adhesive composition described in [3].

[5] The pressure-sensitive adhesive composition according to any one of [1] to [4], wherein the weight average molecular weight of the (meth)acrylic resin is 6.0 × 10 ⁵ to 2.5 × 10 ⁶ in terms of polystyrene.

[6] The pressure-sensitive adhesive composition according to any one of [1] to [5], wherein the proportion of the crosslinking agent (B) is 0.01 to 10 parts by weight based on 100 parts by weight of the (meth)acrylic resin (A).

[7] The silane compound (C) has the following formula (c1)

(Wherein, B represents an alkanediyl group having 1 to 20 carbon atoms or a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and -CH ₂ - constituting the alkanediyl group and the alicyclic hydrocarbon group is -O- or - It may be substituted with CO-, R ¹ represents an alkyl group having 1 to 5 carbon atoms, and R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are each independently an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms. represents the flag)

The adhesive composition according to any one of [1] to [6], which is a silane compound represented by .

[8] B in formula (c1) is an alkanediyl group having 1 to 10 carbon atoms, R ¹ is an alkyl group having 1 to 5 carbon atoms, and R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently have a carbon number The adhesive composition according to [7], which is an alkoxy group of 1 to 5.

[9] The pressure-sensitive adhesive composition according to any one of [1] to [8], wherein the proportion of the silane compound (C) is 0.01 to 10 parts by weight based on 100 parts by weight of the (meth)acrylic resin (A).

[10] The adhesive composition according to any one of [1] to [9], wherein the gel fraction of the adhesive formed from the adhesive composition is 50 to 95%.

[11] A pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition is bonded to a glass substrate, and the adhesive strength of the pressure-sensitive adhesive layer after 24 hours under the conditions of a temperature of 23° C. and a relative humidity of 50% is 0.5 to 0.5 at a peeling speed of 300 mm/min. The adhesive composition according to any one of [1] to [10], which is 10 N/25 mm.

[12] The adhesive composition according to any one of [1] to [11], which is used for forming an adhesive layer laminated on an optical film.

The adhesive composition of the present invention can form an adhesive layer with excellent durability even under harsh durability conditions.

1 is a schematic cross-sectional view showing an example of an optical film with an adhesive layer formed from an adhesive composition according to the present invention.
Figure 2 is a schematic cross-sectional view showing an example of the layer structure of a polarizing plate.
Figure 3 is a schematic cross-sectional view showing another example of the layer structure of a polarizing plate.
4 is a schematic cross-sectional view showing an example of an optical laminate including an optical film with an adhesive layer formed from the adhesive composition according to the present invention.
Figure 5 is a schematic cross-sectional view showing an example of an optical laminate including an optical film with an adhesive layer formed from the adhesive composition according to the present invention.
Figure 6 is a schematic cross-sectional view showing another example of an optical laminate including an optical film with an adhesive layer formed from the adhesive composition according to the present invention.
Figure 7 is a schematic cross-sectional view showing another example of an optical laminate including an optical film with an adhesive layer formed from the adhesive composition according to the present invention.
Figure 8 is a schematic cross-sectional view showing another example of an optical laminate including an optical film with an adhesive layer formed from the adhesive composition according to the present invention.

[1] Adhesive composition

The adhesive composition of the present invention includes a (meth)acrylic resin (A), a crosslinking agent (B), and a silane compound (C).

[1-1] (meth)acrylic resin (A)

The (meth)acrylic resin (A) is a polymer or copolymer containing structural units derived from (meth)acrylic monomers as a main component (preferably containing 50% by weight or more), and has the following formulas (a1) and (a2) It includes structural units derived from the hydroxyl group-containing (meth)acrylate shown in .

(In the formula, n represents an integer of ¹ to 4, A ¹ represents a hydrogen atom or an alkyl group, and good night)

(In the formula, m represents an integer of 5 or more, A ² represents a hydrogen atom or an alkyl group, X ² represents a methylene group which may have a substituent, and the substituents may be the same or different)

That is, since the (meth)acrylic resin (A) of the present invention has hydroxyalkyl groups of different carbon chain lengths (n and m) in the side chain, in the adhesive layer formed from the adhesive composition, the (meth)acrylic resin (A) has different carbon chain lengths (n and m) in the side chain. It is estimated that the cross-linking density can be optimized. By optimizing this crosslink density, it is possible to form an adhesive layer with an excellent balance between hardness and softness (or with optimal hardness), thereby improving durability and preventing peeling (or lifting) of the interface even in a high temperature environment. Foaming can be effectively suppressed. Moreover, even if strong shrinkage stress occurs, the adhesive layer can effectively relieve the stress, preventing whitening from occurring due to shrinkage of the optical film (e.g., deflection plate). Furthermore, reworkability (peelability) can also be improved by optimizing the crosslinking density. In this specification, durability refers to the ability to suppress lifting or peeling at the interface between the adhesive layer and the optical member adjacent to it, for example, in a high temperature environment, in a high temperature and high humidity environment, or in an environment where high and low temperatures are repeated. This refers to properties that can prevent problems such as foaming of the adhesive layer (sometimes called peeling resistance) and properties that can suppress problems such as foaming of the adhesive layer (sometimes called foaming resistance). In addition, in the present invention, cohesive fracture resistance refers to a characteristic that can suppress cohesive fracture (or tearing) of the adhesive layer.

In formulas (a1) and (a2), X ¹ and X ² represent a methylene group that may have a substituent. Examples of this substituent include halogen atoms (fluorine atom, chlorine atom, bromine atom, iodine atom), alkyl groups (e.g. methyl group, ethyl group, propyl group, isopropyl group, butyl group, s-butyl group, t-butyl group, pentyl group). , C _1-10 alkyl group such as hexyl group, preferably C _1-6 alkyl group, more preferably C _1-3 alkyl group), cycloalkyl group (cyclopentyl group, cyclohexyl group, etc.), aryl group [phenyl group, alkyl group, etc. phenyl group (tolyl group, xylyl group, etc.)], aralkyl group (benzyl group, etc.), alkoxy group (e.g., C _1-4 alkoxy group such as methoxy group, ethoxy group, etc.), polyoxyalkylene group (e.g., deoxyethylene group, etc. ), cycloalkoxy group (e.g., C _5-10 cycloalkyloxy group such as cyclohexyloxy group, etc.), aryloxy group (e.g., phenoxy group, etc.), aralkyloxy group (e.g., benzyloxy group, etc.), alkylthio group (e.g., C _1-4 alkylthio groups such as methylthio groups and ethylthio groups, etc.), cycloalkylthio groups (e.g. cyclohexylthio groups, etc.), arylthio groups (e.g. thiophenoxy groups, etc.), aralkylthio groups (e.g. benzyl) thio group, etc.), acyl group (e.g., acetyl group, etc.), nitro group, cyano group, etc. Among these, halogen atoms, alkyl groups, alkoxy groups, aryloxy groups, etc. are preferable, and alkyl groups (such as methyl groups, ethyl groups, etc.) are especially preferable.

A ¹ and A ² each represent a hydrogen atom or an alkyl group, and the alkyl group may be an alkyl group exemplified by X ¹ and X ² (preferably a methyl group, etc.).

In formula (a1), n represents an integer of 1 to 4, preferably an integer of 1 to 3, and more preferably 2. Furthermore, in formula (a2), m is an integer of 5 or more (e.g., an integer of 5 to 20), preferably 5 to 15 (e.g., an integer of 5 to 11), more preferably 5 to 9 (e.g., an integer of 5 to 7). integer), especially 5. Additionally, m may be an even number of 5 or more (e.g., 6, 8, 10, 12, etc.), or may be an odd number of 5 or more (e.g., 5, 7, 9, 11, etc.).

Specific examples of hydroxy group-containing (meth)acrylate (a1) include 1-hydroxymethyl (meth)acrylate, 1-hydroxyethyl (meth)acrylate, 1-hydroxyheptyl (meth)acrylate, and (meth)acrylic acid. 1-hydroxyC _1-8 alkyl (meth)acrylic acid such as 1-hydroxybutyl and 1-hydroxypentyl (meth)acrylic acid; 2-hydroxyethyl (meth)acrylic acid, 2-hydroxypropyl (meth)acrylic acid, 2-hydroxybutyl (meth)acrylic acid, 2-hydroxypentyl (meth)acrylic acid, 2-hydroxyhexyl (meth)acrylic acid, etc. (meth)acrylic acid 2-hydroxyC _2-9 alkyl; (meth)acrylic acid 3-hydroxypropyl, (meth)acrylic acid 3-hydroxybutyl, (meth)acrylic acid 3-hydroxypentyl, (meth)acrylic acid 3-hydroxyhexyl, (meth)acrylic acid 3-hydroxyheptyl, etc. (meth)acrylic acid 3-hydroxyC _3-10 alkyl; (meth)acrylic acid 4-hydroxybutyl, (meth)acrylic acid 4-hydroxypentyl, (meth)acrylic acid 4-hydroxyhexyl, (meth)acrylic acid 4-hydroxyheptyl, (meth)acrylic acid 4-hydroxyoctyl, etc. (meth)acrylic acid 4-hydroxyC _4-11 alkyl; Examples include 2-chloro-2-hydroxypropyl (meth)acrylic acid, 3-chloro-2-hydroxypropyl (meth)acrylic acid, and 2-hydroxy-3-phenoxypropyl (meth)acrylic acid. Among these, from the viewpoint of durability, hydroxy-containing (meth)acrylates where n is 2 such as 2-hydroxyethyl acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate; Hydroxy-containing (meth)acrylates with n of 3, such as 3-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 3-hydroxypentyl (meth)acrylate, are preferred. In particular, the hydroxy-containing (meth)acrylate where n is 2 is preferable, and among these, 2-hydroxyethyl (meth)acrylate is preferable.

Specific examples of hydroxyl group-containing (meth)acrylate (a2) include 5-hydroxypentyl (meth)acrylic acid, 5-hydroxyhexyl (meth)acrylic acid, 5-hydroxyheptyl (meth)acrylic acid, and (meth)acrylic acid. 5-hydroxyC _5-12 alkyl (meth)acrylic acid, such as 5-hydroxyoctyl and 5-hydroxynonyl (meth)acrylic acid; (meth)acrylic acid 6-hydroxyhexyl, (meth)acrylic acid 6-hydroxyheptyl, (meth)acrylic acid 6-hydroxyoctyl, (meth)acrylic acid 6-hydroxynonyl, (meth)acrylic acid 6-hydroxydecyl, etc. (meth)acrylic acid 6-hydroxyC _6-13 alkyl; (meth)acrylic acid 7-hydroxyheptyl, (meth)acrylic acid 7-hydroxyoctyl, (meth)acrylic acid 7-hydroxynonyl, (meth)acrylic acid 7-hydroxydecyl, (meth)acrylic acid 7-hydroxyundecyl (meth)acrylic acid 7-hydroxyC _7-14 alkyl; (meth)acrylic acid 8-hydroxyoctyl, (meth)acrylic acid 8-hydroxynonyl, (meth)acrylic acid 8-hydroxydecyl, (meth)acrylic acid 8-hydroxyundecyl, (meth)acrylic acid 8-hydroxydode (meth)acrylic acid 8-hydroxyC _8-15 alkyl such as Sil; (meth)acrylic acid 9-hydroxynonyl, (meth)acrylic acid 9-hydroxydecyl, (meth)acrylic acid 9-hydroxyundecyl, (meth)acrylic acid 9-hydroxydodecyl, (meth)acrylic acid 9-hydroxy (meth)acrylic acid 9-hydroxyC _9-16 alkyl such as tridecyl; 10-hydroxydecyl (meth)acrylic acid, 10-hydroxyundecyl (meth)acrylic acid, 10-hydroxydodecyl (meth)acrylic acid, 10-hydroxytridecyl acrylic acid, 10-hydroxytetradecyl (meth)acrylic acid (meth)acrylic acid 10-hydroxyC _10-17 alkyl; 11-hydroxyundecyl (meth)acrylic acid, 11-hydroxydodecyl (meth)acrylic acid, 11-hydroxytridecyl (meth)acrylic acid, 11-hydroxytetradecyl (meth)acrylic acid, 11- (meth)acrylic acid (meth)acrylic acid 10-hydroxyC _11-18 alkyl such as hydroxypentadecyl; (meth)acrylic acid 12-hydroxyC _12-19 alkyl such as 12-hydroxydodecyl (meth)acrylic acid, 12-hydroxytridecyl (meth)acrylic acid, and 12-hydroxytetradecyl (meth)acrylic acid; (meth)acrylic acid 13-hydroxyC _13-20 alkyl such as 13-hydroxypentadecyl (meth)acrylic acid, 13-hydroxytetradecyl (meth)acrylic acid, and 13-hydroxypentadecyl (meth)acrylic acid; (meth)acrylic acid 14-hydroxyC _14-21 alkyl such as 14-hydroxytetradecyl (meth)acrylic acid and 14-hydroxypentadecyl (meth)acrylic acid; and 15-hydroxyC _15-22 alkyl (meth)acrylic acid, such as 15-hydroxypentadecyl (meth)acrylic acid and 15-hydroxyheptadecyl (meth)acrylic acid. Among these, from the viewpoint of durability, (meth)acrylic acid 5-hydroxypentyl, (meth)acrylic acid 5-hydroxyhexyl, (meth)acrylic acid 5-hydroxyheptyl, (meth)acrylic acid 5-hydroxyoctyl, (meth)acrylic acid ) Hydroxy-containing (meth)acrylates with n of 5, such as 5-hydroxynonyl acrylate, are preferable, and 5-hydroxypentyl (meth)acrylate is especially preferable.

The proportion of structural units derived from the hydroxy group-containing (meth)acrylate represented by formula (a1) is preferably 1.5 to 4.5 parts by weight, based on 100 parts by weight of all structural units constituting the (meth)acrylic resin, and the formula (a1) is preferably 1.5 to 4.5 parts by weight. The ratio of the structural unit derived from the hydroxyl group-containing (meth)acrylate represented by a2) is preferably 0.25 to 1.0 parts by weight. In addition, the ratio (weight ratio) of the structural unit derived from the hydroxyl group-containing (meth)acrylate represented by formula (a1) and the structural unit derived from the hydroxyl group-containing (meth)acrylate represented by formula (a2) is: There is no particular limitation as long as it is the above range, but preferably (a1)/(a2) = 13/1 to 3/1 (e.g. 11/1 to 3/1), more preferably 9/1 to 4/1, especially Even 7/1 to 5/1 is fine. If it is within the above range, it is advantageous for forming an optimal crosslinked structure, and properties such as durability can be improved.

The (meth)acrylic resin (A) may contain a structural unit derived from the alkyl acrylate (a3) and a structural unit derived from the substituent-containing alkyl acrylate (a4).

Among alkyl acrylates (a3), alkyl acrylates (a3-1) having a homopolymer glass transition temperature (Tg) of less than 0°C include, for example, ethyl acrylate, n- and i-propyl acrylate, n- and i- Butyl acrylate, n-pentyl acrylate, n- and i-hexyl acrylate, n-heptyl acrylate, n- and i-octyl acrylate, 2-ethylhexyl acrylate, n- and i-nonyl acrylate, Examples include linear or branched alkyl acrylates in which the alkyl group has about 2 to 12 carbon atoms, such as n- and i-decyl acrylate and n-dodecyl acrylate. The alkyl acrylate (a3) may be an alkyl acrylate (cycloalkyl acrylate) having an alicyclic structure, but from the viewpoint of followability to optical films (or flexibility or adhesiveness), alkyl acrylate with 2 to 10 carbon atoms, Preferably alkyl acrylates having 3 to 8 carbon atoms, more preferably alkyl acrylates having 4 to 6 carbon atoms, and especially n-butylalkyl acrylates are preferred. Using n-butylalkyl acrylate can improve followability, and for example, peeling resistance is advantageous. These alkyl acrylates (a3-1) can be used individually or in combination of two or more types.

Alkyl acrylates (a3-2) whose homopolymer Tg is 0°C or higher include methyl acrylate, cycloalkyl acrylate (e.g., cyclohexyl acrylate, isoboronyl acrylate), stearyl acrylate, and t-butyl acrylate. and methyl acrylate, and methyl acrylate is particularly preferable. Using methyl acrylate can increase strength, which is advantageous against, for example, cohesive failure. These alkyl acrylates (a3-2) can be used individually or in combination of two or more types. Additionally, for the Tg of the alkyl acrylate homopolymer, reference can be made to literature values such as, for example, POLYMER HANDBOOK (Wiley-Interscience).

The ratio of structural units derived from alkyl acrylate in the (meth)acrylic resin (A) is 100 parts by weight of all structural units constituting the (meth)acrylic resin (A) from the viewpoint of durability and reworkability of the adhesive layer. For example, it is 40 parts by weight or more (e.g., 50 to 98 parts by weight), preferably 60 parts by weight or more (e.g., 70 to 95 parts by weight), and more preferably 70 parts by weight or more (e.g., 80 to 90 parts by weight). )am.

By using an alkyl acrylate with a homopolymer Tg of less than 0°C and an alkyl acrylate with a homopolymer Tg of 0°C or more, both cohesive fracture resistance and followability (foaming resistance and peeling resistance) can be achieved, making it possible to produce optical films (e.g. Polarizer) can improve durability against dimensional changes.

The ratio (weight ratio) of the structural units derived from alkyl acrylate (a3-1) with a homopolymer glass transition temperature of less than 0°C and the structural units derived from alkyl acrylate (a3-2) with a glass transition temperature of 0°C or higher is (a3) -1)/(a3-2)=20/80 to 95/5 (e.g., 30/70 to 90/10), preferably 40/60 to 85/15, more preferably 55/45 to 75/25. am. If it is within the above range, durability can be further improved. As the ratio of structural units derived from alkyl acrylate (a3-1) with a glass transition temperature of less than 0°C increases, the followability improves. As the proportion of structural units derived from alkyl acrylate (a3-2) with a glass transition temperature of 0°C or higher increases, the cohesive fracture resistance improves.

Examples of the substituent-containing alkyl acrylate (a4) include alkyl acrylate (a3-1) in which a substituent is introduced into the alkyl group (the hydrogen atom of the alkyl group is replaced by a substituent). This substituent may be, for example, an aryl group (eg, phenyl group), an aryloxy group (phenoxy group), or an alkoxy group (eg, methoxy group, ethoxy group, etc.). Examples of the substituent-containing alkyl acrylate (a3-3) include alkoxyalkyl acrylate (such as 2-methoxyethyl acrylate, ethoxymethyl acrylate, etc.), aryloxyalkyl acrylate (such as phenoxyethyl acrylate, etc.), Aryloxy polyalkylene glycol monoacrylate, polyalkylene glycol monoacrylate, etc. can be mentioned. These alkyl acrylates (a3-3) can be used individually or in combination of two or more types. By including an alkyl acrylate containing an aromatic ring such as an aryl group or an aryloxy group, the whitening phenomenon of the polarizing plate during a durability test can be improved. In addition, the alkylene groups of aryloxypolyalkylene glycol monoacrylate and polyalkylene glycol monoacrylate include, for example, C _1-6 alkylene groups such as methylene group, ethylene group, propylene group (preferably ethylene group, etc.), etc. Alternatively, the number of repeating units of the oxyalkylene group may be, for example, 2 to 7, preferably 2 to 5 (especially 2), from the viewpoint of durability of the adhesive layer formed from the adhesive composition. In the present invention, since an optimal crosslinking structure (or crosslinking density) can be formed by including a (meth)acrylic resin (A) and a crosslinking agent (B) described later in the adhesive composition, the number of repeating units of the oxyalkylene group is Even though it is relatively small, it shows good reworkability. Specifically, for example, phenoxydi to heptaC _1-3 alkylene glycol-acrylate such as phenoxydiethylene glycol acrylate, di to heptaC _1-3 alkylene-monoacrylate such as diethylene glycol monoacrylate, etc. can be mentioned.

The ratio of structural units derived from substituent-containing alkyl acrylate is, for example, 0 to 30 parts by weight (e.g., 1 to 25 parts by weight), preferably, based on 100 parts by weight of all structural units constituting the (meth)acrylic resin (A). is 3 to 20 parts by weight, more preferably 5 to 15 parts by weight.

The (meth)acrylic resin (A) is composed of monomers (a5) other than hydroxyl group-containing (meth)acrylates (a1) and (a2), alkyl acrylates (a3), and substituent-containing alkyl acrylates (a4). It may include derived structural units. Other monomers can be used individually or in combination of two or more types. Other monomers (a5) include monomers having polar functional groups other than hydroxyl groups (a5-1), acrylamide-based monomers (a5-2), methacrylates (methacrylic acid esters) (a5-3), and methacrylamides. A monomer (a5-4), a styrene monomer (a5-5), a vinyl monomer (a5-6), and a monomer (a5-7) having a plurality of (meth)acryloyl groups in the molecule are included.

Examples of the monomer (a5-1) having a polar functional group other than a hydroxy group include (meth)acrylate having a substituent such as a carboxyl group, a substituted or unsubstituted amino group, and a heterocyclic group such as an epoxy group. Specifically, acryloylmorpholine, vinylcaprolactam, N-vinyl-2-pyrrolidone, vinylpyridine, tetrahydrofurfuryl (meth)acrylate, caprolactone modified tetrahydrofurfuryl acrylate, 3,4 -Monomers having a heterocyclic group such as epoxycyclohexylmethyl (meth)acrylate, glycidyl (meth)acrylate, and 2,5-dihydrofuran; Monomers having a substituted or unsubstituted amino group such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and dimethylaminopropyl (meth)acrylate; monomers having a carboxyl group such as (meth)acrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, and carboxyalkyl (meth)acrylate (e.g., carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate). You can. These monomers can be used individually or in combination of two or more types. Additionally, from the viewpoint of preventing deterioration of the peelability of the separate film that can be laminated on the adhesive layer, it is preferable that it does not substantially contain structural units derived from monomers having an amino group. Here, substantially not included means less than 1.0 parts by weight based on 100 parts by weight of all structural units constituting the (meth)acrylic resin (A).

In the present invention, since high durability is shown even if it does not contain structural units derived from monomers having a carboxyl group (structural units derived from carboxyl group-containing (meth)acrylates) that are thought to increase ITO corrosion resistance, durability and ITO corrosion resistance are compatible. You can.

On the other hand, durability can be further improved by containing a structural unit derived from a monomer having a carboxyl group (a structural unit derived from a carboxyl group-containing (meth)acrylate). In the present invention, durability can be effectively improved even if the proportion of structural units derived from carboxyl group-containing (meth)acrylate is small, so it is possible to improve durability while suppressing corrosion of ITO.

The ratio of structural units derived from carboxyl group-containing (meth)acrylate is, for example, 5.0 parts by weight or less (e.g., 0 to 3 parts by weight), preferably 1.0 parts by weight, based on 100 parts by weight of structural units derived from (meth)acrylate. or less (e.g. 0 to 0.8 parts by weight), more preferably 0.5 parts by weight or less (e.g. 0.001 to 0.5 parts by weight), even more preferably 0.3 parts by weight or less (e.g. 0.005 to 0.3 parts by weight), especially 0.2 parts by weight or less ( For example, 0.01 to 0.2 parts by weight), especially 0.15 parts by weight or less (for example, 0.05 to 0.15 parts by weight). If it is below the upper limit, ITO corrosion can be suppressed, and if it is above the lower limit, durability can be improved.

Examples of the acrylamide monomer (a5-2) include N-methylol acrylamide, N-(2-hydroxyethyl)acrylamide, N-(3-hydroxypropyl)acrylamide, and N-(4-hydroxy Butyl)acrylamide, N-(5-hydroxypentyl)acrylamide, N-(6-hydroxyhexyl)acrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, N-isopropyl Acrylamide, N-(3-dimethylaminopropyl)acrylamide, N-(1,1-dimethyl-3-oxobutyl)acrylamide, N-[2-(2-oxo-1-imidazolidinyl)ethyl ]Acrylamide, 2-acryloylamino-2-methyl-1-propanesulfonic acid, N-(methoxymethyl)acrylamide, N-(ethoxymethyl)acrylamide, N-(propoxymethyl)acrylamide, N-(1-methylethoxymethyl)acrylamide, N-(1-methylpropoxymethyl)acrylamide, N-(2-methylpropoxymethyl)acrylamide [alias: N-(isobutoxymethyl)acrylamide ], N-(butoxymethyl)acrylamide, N-(1,1-dimethylethoxymethyl)acrylamide, N-(2-methoxyethyl)acrylamide, N-(2-ethoxyethyl)acrylamide , N-(2-propoxyethyl)acrylamide, N-[2-(1-methylethoxy)ethyl]acrylamide, N-[2-(1-methylpropoxy)ethyl]acrylamide, N-[ 2-(2-methylpropoxy)ethyl]acrylamide [alias: N-(2-isobutoxyethyl)acrylamide], N-(2-butoxyethyl)acrylamide, N-[2-(1,1) -dimethylethoxy)ethyl]acrylamide, etc. Among these, N-(methoxymethyl)acrylamide, N-(ethoxymethyl)acrylamide, N-(propoxymethyl)acrylamide, N-(butoxymethyl)acrylamide, N-(2-methylpropyl) Oxymethyl)acrylamide and the like are preferred.

Methacrylates (methacrylic acid esters) (a5-3) include, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, n-octyl methacrylate, and lauryl methacrylate. linear alkyl methacrylates such as; branched alkyl methacrylates such as i-butyl methacrylate, 2-ethylhexyl methacrylate, and i-octyl methacrylate; Isobornyl methacrylate, cyclohexyl methacrylate, dicyclofentanyl methacrylate, cyclododecyl methacrylate, methylcyclohexyl methacrylate, trimethylcyclohexyl methacrylate, t-butylcyclohexyl methacrylate, Mono- or dicycloalkyl methacrylates such as cyclohexylphenyl methacrylate; Alkoxyalkyl methacrylates such as 2-methoxyethyl methacrylate and ethoxymethyl methacrylate; Aralkyl methacrylates such as benzyl methacrylate, etc. can be mentioned.

Examples of the methacrylamide monomer (a5-4) include methacrylamide monomers corresponding to the acrylamide monomers described in (a5-2).

Examples of the styrene-based monomer (a5-5) include styrene; Alkyl styrene, such as methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, triethyl styrene, propyl styrene, butyl styrene, hexyl styrene, heptyl styrene, and octyl styrene; Halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, and iodostyrene; nitrostyrene; acetylstyrene; methoxystyrene; Divinylbenzene, etc. can be mentioned.

Examples of the vinyl monomer (a5-6) include fatty acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, and vinyl laurate; Vinyl halides such as vinyl chloride and vinyl bromide; Vinylidene halides such as vinylidene chloride; nitrogen-containing aromatic vinyl such as vinylpyridine, vinylpyrrolidone, and vinylcarbazole; Conjugated diene monomers such as butadiene, isoprene, and chloroprene; and unsaturated nitriles such as acrylonitrile and methacrylonitrile.

Examples of the monomer (a5-7) having multiple (meth)acryloyl groups in the molecule include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and 1,9- Molecules such as 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. A monomer having two (meth)acryloyl groups within it; Monomers having three (meth)acryloyl groups in the molecule, such as trimethylolpropane tri(meth)acrylate, can be mentioned.

In addition, from the viewpoint of the reworkability of the adhesive layer, the (meth)acrylic resin (A) is methacrylate (methacrylic acid ester) (a5-3), methacrylamide monomer (a5-4), etc. It is preferable that the ratio (or content) of structural units derived from the system monomer is small. That is, the ratio of this structural unit is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, and especially 1 part by weight, based on 100 parts by weight of all structural units constituting the (meth)acrylic resin (A). Even less than 100 parts by weight is fine.

In addition, the ratio of structural units derived from other monomers (a5) is, for example, 0 to 20 parts by weight, preferably 0 to 10 parts by weight, based on 100 parts by weight of all structural units constituting the (meth)acrylic resin (A). (For example, 0.001 to 10 parts by weight), more preferably 0 to 5 parts by weight (For example, 0.01 to 3 parts by weight).

The (meth)acrylic resin (A) has a weight average molecular weight (Mw) converted to standard polystyrene by gel permeation chromatography GPC, for example, 6.0×10 ⁵ to 2.5×10 ⁶ (for example, 8.0×10 ⁵ to 2.5×10 ⁶ ), preferably 1.0×10 ⁶ to 2.0×10 ⁶ , more preferably 1.2×10 ⁶ to 1.8×10 ⁶ (for example, 1.3×10 ⁶ to 1.6×10 ⁶ ). If Mw is below the upper limit, it is advantageous from the viewpoint of coatability when applying the adhesive composition to a substrate, and if Mw is above the lower limit, it is advantageous in improving the followability of the adhesive layer to dimensional changes in the optical film. The molecular weight distribution expressed by the ratio (Mw/Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) is usually 2 to 10, preferably 3 to 8, and more preferably 4 to 6.

Additionally, the (meth)acrylic resin (A) preferably has a single peak in the Mw range of 1.0×10 ³ to 2.5×10 ⁶ on the discharge curve in GPC. Using a (meth)acrylic resin (A) with a peak number of 1 is advantageous for improving the durability of the adhesive layer.

In the above range of the obtained emission curve, “having a single peak” means having only one local maximum in the range of Mw 1.0×10 ³ to 2.5×10 ⁶ . In this specification, a peak is defined as an S/N ratio of 30 or more in the GPC discharge curve. Additionally, the number of peaks in the GPC discharge curve and Mw and Mn of the (meth)acrylic resin (A) can be determined by the GPC measurement conditions described in the Examples section.

When the (meth)acrylic resin (A) is dissolved in ethyl acetate to form a solution with a concentration of 20% by weight, the viscosity at 25°C is preferably 20 Pa·s or less, and is 0.1 to 7 Pa·s. It is more desirable. A viscosity within this range is advantageous from the viewpoint of coatability when applying the pressure-sensitive adhesive composition to a substrate. Additionally, viscosity can be measured by a Brookfield viscometer.

The glass transition temperature (Tg) of the (meth)acrylic resin (A) is, for example, -60 to 0 ° C. (for example, -50 to -10 ° C.), preferably -50 to -20 ° C., more preferably -40 to -40 ° C. -20℃ (for example, -40 to -25℃) is also acceptable. This range is advantageous for improving durability. Additionally, the glass transition temperature can be measured by differential scanning calorimetry (DSC).

The (meth)acrylic resin (A) can be produced by known methods such as solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization, and solution polymerization is particularly preferable. As a solution polymerization method, for example, a monomer and an organic solvent are mixed, a thermal polymerization initiator is added under a nitrogen atmosphere, and the mixture is stirred for about 3 to 15 hours under temperature conditions of about 40 to 90°C (preferably 50 to 80°C). can be mentioned. For reaction control, monomers or thermal polymerization initiators may be added continuously or intermittently during polymerization. This monomer or thermal initiator may be added to an organic solvent.

As a polymerization initiator, a thermal polymerization initiator, a photopolymerization initiator, etc. are used. Examples of the photopolymerization initiator include 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone. As a thermal polymerization initiator, such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile) , 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl-2,2'-azo Azo compounds such as bis(2-methylpropionate) and 2,2'-azobis(2-hydroxymethylpropionitrile); Lauryl peroxide, t-butyl hydroperoxide, benzoyl peroxide, t-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, dipropyl peroxydicarbonate, t-butyl peroxy Organic peroxides such as neodecanoate, t-butylperoxypivalate, and (3,5,5-trimethylhexanoyl)peroxide; Inorganic peroxides such as potassium persulfate, ammonium persulfate, and hydrogen peroxide can be mentioned. Additionally, a redox-based initiator using a combination of peroxide and a reducing agent can also be used.

The ratio of the polymerization initiator is about 0.001 to 5 parts by weight based on 100 parts by weight of the total amount of monomers constituting the (meth)acrylic resin. The polymerization of (meth)acrylic resin may use a polymerization method using active energy rays (for example, ultraviolet rays, etc.).

Examples of organic solvents include aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; Aliphatic alcohols such as propyl alcohol and isopropyl alcohol; Ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone can be mentioned.

[1-2] Cross-linking agent (B)

The adhesive composition includes a crosslinking agent (B). This crosslinking agent (B) reacts with a polar functional group including a hydroxy group in the (meth)acrylic resin (A).

The crosslinking agent (B) is a tolylene diisocyanate-based compound and/or an adduct (adduct) of a tolylene diisocyanate-based compound with a polyhydric alcohol compound (e.g., glycerin, trimethylolpropane, etc.). Examples of tolylene diisocyanate-based compounds include monomethylbenzene diisocyanate such as 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, and 3,5-tolylene diisocyanate. In the present invention, the crosslinking agent (B) reacts with the OH group (hydroxyl group) of the hydroxyalkyl group having different carbon chain lengths (n and m) introduced into the side chain of the (meth)acrylic resin (A), thereby improving durability and durability. Forms a cross-linked structure that is advantageous for rework. In particular, since the crosslinking agent (B) is composed of the tolylene diisocyanate-based compound and/or the polyhydric alcohol compound of the tolylene diisocyanate-based compound, a crosslinked structure with an excellent balance between strength and flexibility can be formed. It can be assumed that there will be, and durability can also be improved. In other words, high durability can be achieved not only when applied to a glass substrate, but also when applied (laminated) to, for example, an ITO substrate. Additionally, since the crosslinking agent (B) is an isocyanate-based compound, it is advantageous from the viewpoint of crosslinking speed and pot life of the adhesive composition.

The proportion of the crosslinking agent (B) is, for example, 0.01 to 10 parts by weight (e.g., 0.05 to 5 parts by weight), preferably 0.1 to 3 parts by weight (e.g., 0.1 to 2 parts by weight), based on 100 parts by weight of the (meth)acrylic resin (A). parts by weight), more preferably 0.2 to 1 part by weight (for example, 0.3 to 0.8 parts by weight). The smaller the upper limit, the more advantageous it is for improving followability (or peeling resistance), and the larger the lower limit, the more advantageous it is for improving cohesion resistance (or foaming resistance) or rework resistance.

[1-3] Silane compound (C)

The adhesive composition includes a silane compound (C). By including this silane compound (C), the adhesion (or adhesion) between the adhesive layer and the metal layer, transparent electrode, glass substrate, etc. can be improved. The silane compound (C) may be any silane compound that can bond with the reactive group (for example, the OH group of the hydroxyl group) of the (meth)acrylic resin (A), such as vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris. (2-methoxyethoxy)silane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyl Toxydimethylsilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxy Silane, 3-mercaptopropyltrimethoxysilane, 1,3-bis(3'-trimethoxypropyl)urea, etc. are mentioned.

Additionally, the silane compound (C) may be a silicone oligomer type compound. If this silicone oligomer is expressed as a combination of monomers, for example, 3-mercaptopropyldi or trimethoxysilane-tetramethoxysilane oligomer, 3-mer Captomethyldi or trimethoxysilane-tetraethoxysilane oligomer, 3-mercaptopropyldi or triethoxysilane-tetramethoxysilane oligomer, 3-mercaptomethyldi or triethoxysilane-tetraethoxysilane oligomer oligomers containing mercaptoalkyl groups, such as; Oligomers in which the mercaptoalkyl group of this mercaptoalkyl group-containing oligomer is substituted with other substituents [3-glycidoxypropyl group, (meth)acryloyloxypropyl group, vinyl group, amino group, etc.] can be mentioned.

The silane compound (C) may preferably be a silane compound represented by the following formula (c1). When the pressure-sensitive adhesive composition contains a silane compound represented by the following formula (c1), adhesion (or adhesiveness) can be further improved, and thus a pressure-sensitive adhesive layer with excellent peel resistance can be formed. Additionally, the adhesive layer has excellent rework properties. In particular, even when the adhesive layer is applied (or laminated) to a transparent electrode (for example, an ITO substrate, etc.) under a high temperature environment, adhesion (or adhesiveness) can be maintained and high durability can be shown.

(Wherein, B represents an alkanediyl group having 1 to 20 carbon atoms or a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and -CH ₂ - constituting the alkanediyl group and the alicyclic hydrocarbon group is -O- or - It may be substituted with CO-, R ¹ represents an alkyl group having 1 to 5 carbon atoms, and R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are each independently an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms. represents the flag)

In formula (c1), B is an alkanediyl group having 1 to 20 carbon atoms such as methylene group, ethylene group, trimethylene group, tetramethylene group, hexamethylene group, heptamethylene group, and octamethylene group; Cyclobutylene group (e.g. 1,2-cyclobutylene group), cyclopentylene group (e.g. 1,2-cyclopentylene group), cyclohexylene group (e.g. 1,2-cyclohexylene group), cyclooctylene group (e.g. 1 divalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, such as , 2-cyclooctylene group); Or it represents a group in which -CH ₂ - constituting the alkanediyl group and the alicyclic hydrocarbon group is substituted with -O- or -CO-. Preferred B is an alkanediyl group having 1 to 10 carbon atoms. R ¹ represents an alkyl group having 1 to 5 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, s-butyl, t-butyl, and pentyl, and R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are each independently an alkyl group having 1 to 5 carbon atoms as exemplified for R ¹ above; Or it represents an alkoxy group having 1 to 5 carbon atoms, such as methoxy group, ethoxy group, propoxy group, i-propoxy group, butoxy group, s-butoxy group, and t-butoxy group. Preferred R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are alkoxy groups having 1 to 5 carbon atoms. These silane compounds (C) can be used individually or in combination of two or more types.

Specific silane compounds (c1) include, for example, (trimethoxysilyl)methane, 1,2-bis(trimethoxysilyl)ethane, 1,2-bis(triethoxysilyl)ethane, and 1,3-bis(trimethoxysilyl)ethane. Methoxysilyl)propane, 1,3-bis(triethoxysilyl)propane, 1,4-bis(trimethoxysilyl)butane, 1,4-bis(triethoxysilyl)butane, 1,5-bis (trimethoxysilyl)pentane, 1,5-bis(triethoxysilyl)pentane, 1,6-bis(trimethoxysilyl)hexane, 1,6-bis(triethoxysilyl)hexane, 1,6 -Bis(tripropoxysilyl)hexane, 1,8-bis(trimethoxysilyl)octane, 1,8-bis(triethoxysilyl)octane, 1,8-bis(tripropoxysilyl)octane, etc. Bis(triC _1-5 alkoxysilyl)C _1-10 alkane; Bis(dimethoxymethylsilyl)methane, 1,2-bis(dimethoxymethylsilyl)ethane, 1,2-bis(dimethoxyethylsilyl)ethane, 1,4-bis(dimethoxymethylsilyl)butane, 1, 4-bis(dimethoxyethylsilyl)butane, 1,6-bis(dimethoxymethylsilyl)hexane, 1,6-bis(dimethoxyethylsilyl)hexane, 1,8-bis(dimethoxymethylsilyl)octane, Bis(diC _1-5 alkoxyC _1-5 alkylsilyl)C _1-10 alkanes such as 1,8-bis(dimethoxyethylsilyl)octane; Bis(monoC 1-5 alkoxy-diC _1-5 alkylsilyl)C _1-10 alkanes such as 1,6-bis(methoxydimethylsilyl)hexane, 1,8-bis( _{methoxydimethylsilyl} )octane, etc. can be mentioned. Among these, 1,2-bis(trimethoxysilyl)ethane, 1,3-bis(trimethoxysilyl)propane, 1,4-bis(trimethoxysilyl)butane, 1,5-bis(trimethoxysilyl)butane, 1,5-bis(trimethoxysilyl)ethane Bis(triC _1-3 alkoxysilyl)C _1-10 alkanes such as toxysilyl)pentane, 1,6-bis(trimethoxysilyl)hexane, and 1,8-bis(trimethoxysilyl)octane are preferred. , especially 1,6-bis(trimethoxysilyl)hexane and 1,8-bis(trimethoxysilyl)octane.

The proportion of the silane compound (C) is, for example, 0.01 to 10 parts by weight (e.g., 0.03 to 5 parts by weight), preferably 0.05 to 3 parts by weight, more preferably, based on 100 parts by weight of the (meth)acrylic resin (A). is 0.1 to 1 part by weight (for example, 0.2 to 0.5 part by weight). If it is below the upper limit, it is advantageous for suppressing bleed-out of the silane compound (C) from the adhesive layer, and if it is above the lower limit, it becomes easy to improve the adhesion (or adhesion) between the adhesive layer and the metal layer or glass substrate, etc., thereby improving peeling resistance. It is advantageous for improving etc.

[1-4] Antistatic agent

The adhesive composition may additionally include an antistatic agent. By including an antistatic agent, the antistatic properties of the adhesive can be improved (for example, problems caused by static electricity that occur when peeling off a release film, protective film, etc.) can be improved. Common antistatic agents include common antistatic agents, and ionic antistatic agents are suitable. Cationic components constituting the ionic antistatic agent include organic cations and inorganic cations. Examples of organic cations include pyridinium cation, imidazolium cation, ammonium cation, sulfonium cation, and phosphonium cation. Examples of inorganic cations include alkali metal cations such as lithium cation, potassium cation, sodium cation, and cesium cation, and alkaline earth metal cations such as magnesium cation and calcium cation. The anionic component constituting the ionic antistatic agent may be either an inorganic anion or an organic anion, but an anionic component containing a fluorine atom is preferred because it has excellent antistatic performance. Examples of the anion component containing a fluorine atom include hexafluorophosphate anion (PF ₆ -), bis(trifluoromethanesulfonyl)imide anion [(CF ₃ SO ₂ ) ₂ N-], and bis(fluorosulfonyl). Ponyl)imide anion [(FSO ₂ ) ₂ N-], tetra(pentafluorophenyl)borate anion [(C ₆ F ₅ ) ₄ B-], etc. These antistatic agents can be used individually or in combination of two or more types. In particular, bis(trifluoromethanesulfonyl)imide anion [(CF ₃ SO ₂ ) ₂ N-], bis(fluorosulfonyl)imide anion [(FSO ₂ ) ₂ N-], tetra(pentafluoro) The phenyl)borate anion [(C ₆ F ₅ ) ₄ B-] is preferred.

Since the antistatic performance of the adhesive composition is excellent in stability over time, an ionic antistatic agent that is solid at room temperature is preferred.

The ratio of the antistatic agent may be, for example, 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, and more preferably 1 to 3 parts by weight, based on 100 parts by weight of the (meth)acrylic resin (A).

[1-5] Other ingredients

The adhesive composition may contain additives such as solvents, crosslinking catalysts, ultraviolet absorbers, weathering stabilizers, tackifiers, plasticizers, softeners, dyes, pigments, inorganic fillers, and light-scattering fine particles, singly or in combination of two or more. In addition, it is also useful to mix an ultraviolet curable compound in an adhesive composition, form an adhesive layer, and then cure it by irradiating ultraviolet rays to obtain a harder adhesive layer. Examples of crosslinking catalysts include amine compounds such as hexamethylenediamine, ethylenediamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethylenetetramine, isophoronediamine, trimethylenediamine, polyamino resin, and melamine resin. can be mentioned.

The adhesive composition may contain a rust inhibitor from the viewpoint of increasing the metal corrosion resistance of the adhesive layer. Examples of the rust preventive include triazole-based compounds such as benzotriazole-based compounds; Thiazole-based compounds such as benzothiazole-based compounds; Imidazole-based compounds such as benzylimidazole-based compounds; imidazoline-based compounds; Quinoline-based compounds; Pyridine-based compounds; Pyrimidine-based compounds; indole-based compounds; Amine-based compounds; Urea-based compounds; sodium benzoate; Benzylmercapto-based compounds; di-sec-butyl sulfide; and diphenyl sulfoxide.

[2] Composition and manufacturing method of an adhesive layer and an optical film equipped with an adhesive layer

The adhesive composition of the present invention can form an adhesive layer by performing surface activation treatment (eg, plasma treatment, corona treatment, etc.). Typically, the adhesive layer is laminated on at least one side of the optical film.

1 is a schematic cross-sectional view showing an example of an optical film with an adhesive layer formed from an adhesive composition according to the present invention. The optical film 1 with an adhesive layer shown in FIG. 1 is an optical film in which an optical film 10 and an adhesive layer 20 are laminated on one side of the optical film. This adhesive layer 20 is usually laminated directly on the surface of the optical film 10. Additionally, the adhesive layer 20 may be laminated on both sides of the optical film 10.

When laminating the adhesive layer 20 on the surface of the optical film 10, a primer layer is formed on the bonding surface of the optical film 10 and/or the bonding surface of the adhesive layer 20, or the surface activation treatment is performed. It is preferable to perform (e.g., plasma treatment, corona treatment, etc.), and it is especially preferable to perform corona treatment.

When the optical film 10 is a single-sided protective polarizer as shown in FIG. 2, the adhesive layer 20 is usually laminated on the polarizer side, that is, on the side opposite to the first resin film 3 in the polarizer 2. (preferably directly laminated). When the optical film 10 is a double-sided protective polarizing plate as shown in FIG. 3, the adhesive layer 20 may be laminated on the outer surface of any one of the first and second resin films 3 and 4, and on both sides. It may be laminated on the outer surface.

An antistatic layer may be separately provided between the optical film 10 and the adhesive layer 20. As the antistatic layer, silicon-based materials such as polysiloxane, inorganic metal-based materials such as tin-doped indium oxide and tin-doped antimony oxide, and organic polymer-based materials such as polythiophene, polystyrene sulfonic acid, and polyaniline can be used.

The optical film 1 with an adhesive layer may include a separate film (release film) laminated on the outer surface of the adhesive layer 20. This separate film is usually peeled and removed when the adhesive layer 20 is used (for example, when laminated to a transparent conductive electrode or a glass substrate). The separate film is, for example, a film made of various resins such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, and polyate, even if the surface on which the adhesive layer 20 is formed has been subjected to release treatment such as silicone treatment. good night.

The optical film 1 with an adhesive layer is prepared by dissolving or dispersing each component of the adhesive composition in a solvent to form a solvent-containing adhesive composition, which is then applied and dried on the surface of the optical film 10 to form an adhesive layer. It can be obtained by forming (20). In addition, the optical film 1 with an adhesive layer is formed by forming the adhesive layer 20 on the release-treated surface of the separate film as described above, and laminating this adhesive layer 20 on the surface of the optical film 10 ( It can also be obtained by transcription.

The thickness of the adhesive layer is usually 2 to 40 ㎛, and is preferably 5 to 30 ㎛, more preferably 10 ㎛, from the viewpoint of durability of the optical film with an adhesive layer and reworkability of the optical film with an adhesive layer, etc. It is ∼25 μm. If it is below the upper limit, the adhesive layer will have good followability (or followability) to dimensional changes in the optical film, and if it is above the lower limit, rework will be good.

The adhesive layer preferably exhibits a storage modulus of 0.1 to 5 MPa in the temperature range of 23 to 80°C. Accordingly, the durability of the optical film equipped with an adhesive layer can be more effectively improved. “Exhibiting a storage elastic modulus of 0.1 to 5 MPa in the temperature range of 23 to 80°C” means that the storage elastic modulus is a value within the above range at any temperature in this range. Since the storage elastic modulus usually gradually decreases as the temperature rises, if the storage elastic moduli at 23°C and 80°C are both within the above range, it can be assumed that the storage elastic modulus is within the above range at the temperature in this range. The storage modulus of the adhesive layer can be measured using a commercially available viscoelasticity measuring device, such as the viscoelasticity measuring device "DYNAMIC ANALYZER RDA II" manufactured by REOMETRIC.

Gel fraction can be used as an indicator of crosslinking density. The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention has a certain crosslinking density and thus exhibits a certain gel fraction. That is, the gel fraction of the adhesive layer is, for example, 50 to 95% by weight (eg, 55 to 93% by weight), preferably 60 to 90% by weight (eg, 65 to 90% by weight), more preferably 70 to 85% by weight. % (for example, 80 to 85% by weight) may be sufficient. If the gel fraction is more than the lower limit, it is advantageous for the foaming resistance (cohesive fracture resistance) and rework resistance of the adhesive layer, and if the gel fraction is less than the upper limit, it is advantageous for peeling resistance. Additionally, the gel fraction can be measured by the method described in the Examples section.

The adhesive layer formed from the adhesive composition of the present invention has a predetermined adhesive force. That is, the adhesive force of the adhesive layer 24 hours after bonding the adhesive layer to a glass substrate under the conditions of a temperature of 23° C. and a relative humidity of 50% is, for example, 0.5 to 25 N (e.g., 0.5 N) at a peeling speed of 300 mm/min. to 20 N), preferably 0.5 to 10 N (for example, 1 to 10 N), and more preferably 1 to 8 N. If the adhesion is above the lower limit, the adhesion (or adhesiveness) is improved, which is advantageous for peeling resistance, etc., and if the adhesion is below the upper limit, it is advantageous for rework. Additionally, adhesive force can be measured by the method described in the Examples section.

[2-1] Optical film

The optical film 10 constituting the optical film 1 with an adhesive layer may be any of various optical films (films with optical properties) that can be used in image display devices such as liquid crystal displays. This optical film 10 may have a single-layer structure (e.g., optical functional films such as polarizer, retardation film, brightness enhancement film, anti-glare film, anti-reflection film, diffusion film, light-collecting film, etc.) or may have a multi-layer structure (e.g., polarizer, retardation film, etc.) etc.) is also fine. The optical film 10 is preferably a polarizing plate, polarizer, retardation plate, or retardation film, and particularly preferably a polarizing plate or polarizer. In addition, in this specification, an optical film means a film that functions for image display (display screen, etc.) (for example, a film that functions to improve the visibility of images). In addition, in this specification, a polarizing plate means a resin film or a resin layer laminated on at least one side of a polarizer, and a retardation plate means a resin film or a resin layer laminated on at least one side of the retardation film.

[2-2] Polarizer

2 and 3 are schematic cross-sectional views showing examples of the layer structure of a polarizing plate. The polarizing plate 10a shown in FIG. 2 is a single-sided protection polarizing plate in which the first resin film 3 is laminated (or laminated bonded) on one side of the polarizer 2, and the polarizing plate 10b shown in FIG. 3 is a polarizer ( It is a double-sided protective polarizing plate in which a second resin film 4 is further laminated (or laminated bonded) on the other side of 2). The first and second resin films 3 and 4 can be bonded to the polarizer 2 through an adhesive layer or pressure-sensitive adhesive layer (not shown). Additionally, the polarizing plates 10a and 10b may contain films or layers other than the first and second resin films 3 and 4.

The polarizer 2 is a film that has the property of absorbing linearly polarized light having a vibration plane parallel to its absorption axis and transmitting linearly polarized light having a vibration plane orthogonal to the absorption axis (parallel to the transmission axis), for example, polyvinyl A film in which a dichroic dye is adsorbed and oriented on an alcohol-based resin film can be used. Examples of dichroic dyes include iodine and dichroic organic dyes.

Polyvinyl alcohol-based resin can be obtained by saponifying polyvinyl acetate-based resin. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, monomers copolymerizable with vinyl acetate (e.g., unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, (meth)acrylamide having an ammonium group, etc.) A copolymer with vinyl acetate, etc. can be mentioned.

The saponification degree of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, for example, polyvinyl formal or polyvinyl acetal modified with aldehydes. The average degree of polymerization of polyvinyl alcohol-based resin is usually 1,000 to 10,000, preferably 1,500 to 5,000. Additionally, the average degree of polymerization of the polyvinyl alcohol-based resin can be determined based on JIS K 6726.

Usually, a polyvinyl alcohol-based resin film is used as the raw film of the polarizer 2. Polyvinyl alcohol-based resin can be formed into a film by a known method. The thickness of the raw film is usually 1 to 150 μm, and considering ease of stretching, etc., it is preferably 10 μm or more.

The polarizer 2 is, for example, a step of uniaxially stretching the fabric film, a step of dyeing the film with a dichroic dye and adsorbing the dichroic dye, a step of treating the film with an aqueous boric acid solution, and a step of washing the film. and finally dried and manufactured. The thickness of the polarizer 2 is usually 1 to 30 μm, and from the viewpoint of thinning the optical film 1 with an adhesive layer, it is preferably 20 μm or less, more preferably 15 μm or less, and especially 10 μm or less.

The polarizer 2, which is formed by adsorbing and orienting a dichroic dye on a polyvinyl alcohol-based resin film, 1) uses a single film of the polyvinyl alcohol-based resin film as a raw film, and uniaxially stretching this film and applying the dichroic dye. In addition to the method of performing the dyeing treatment, 2) coating the base film with a coating solution (aqueous solution, etc.) containing a polyvinyl alcohol-based resin, drying it to obtain a base film having a polyvinyl alcohol-based resin layer, and then applying this to the base film. It can also be obtained by uniaxially stretching each film, dyeing the polyvinyl alcohol-based resin layer after stretching with a dichroic dye, and then peeling and removing the base film. As the base film, a film made of a thermoplastic resin such as a thermoplastic resin that can form the first and second resin films 3 and 4 described later can be used, preferably a polyester resin such as polyethylene terephthalate, It is a film made of polycarbonate-based resin, cellulose-based resin such as triacetylcellulose, cyclic polyolefin-based resin such as norbornene-based resin, and polystyrene-based resin. Using the method of 2) above, it becomes easy to manufacture a thin film polarizer 2, and for example, it also becomes easy to manufacture a polarizer 2 with a thickness of 7 μm or less.

The first and second resin films 3 and 4 are each independently made of a light-transmitting, preferably optically transparent thermoplastic resin, such as chain polyolefin-based resin (polyethylene-based resin, polypropylene-based resin, etc.), cyclic polyolefin-based resin. Polyolefin-based resins such as resins (norbornene-based resins, etc.); Cellulose-based resins (cellulose ester-based resins, etc.); Polyester resins (polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, etc.); polycarbonate-based resins (such as polycarbonates derived from bisphenol such as 2,2-bis(4-hydroxyphenyl)propane); (meth)acrylic resin; polystyrene-based resin; polyetheretherketone-based resin; A film made of polysulfone resin or a mixture or copolymer thereof may be used. Among these, the first and second resin films 3 and 4 are preferably films composed of cyclic polyolefin resin, polycarbonate resin, cellulose resin, polyester resin, and (meth)acrylic resin, respectively. , In particular, it is preferable that it is a film composed of cellulose resin and cyclic polyolefin resin.

Examples of the linear polyolefin resin include homopolymers of linear olefins such as polyethylene resin and polypropylene resin, and copolymers of two or more types of linear olefins.

Cyclic polyolefin resin is a general term for resins containing cyclic olefins such as norbornene, tetracyclododecene (aka: dimethanooctahydronaphthalene) or their derivatives as polymerized units. Examples of the cyclic polyolefin resin include ring-opening (co)polymers of cyclic olefins and their hydrogenated products, addition polymers of cyclic olefins, copolymers of cyclic olefins with chain olefins such as ethylene and propylene, or aromatic compounds having a vinyl group, and unsaturated carboxylic acids thereof. Modified (co)polymers modified with boxylic acid or its derivatives can be mentioned. Among these, norbornene-based resins using norbornene-based monomers such as norbornene and polycyclic norbornene-based monomers as cyclic olefins are preferable.

The cellulose-based resin is preferably a cellulose ester-based resin, that is, a partially or fully esterified product of cellulose, and examples include acetic acid ester, propionic acid ester, butyric acid ester of cellulose, and mixed esters thereof. Among these, triacetylcellulose, diacetylcellulose, cellulose acetate propionate, cellulose acetate butyrate, etc. are preferable.

Polyester-based resin is a resin other than the above cellulose ester-based resin that has an ester bond, and is generally composed of a polycondensate of polyhydric carboxylic acid or its derivative and polyhydric alcohol. Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexanedimethyl terephthalate, and polycyclohexanedimethylnaphthalate. Phthalates, etc. can be mentioned.

Polycarbonate-based resin is a polyester formed from carbonic acid and glycol or bisphenol. Among these, aromatic polycarbonate having diphenylalkane in the molecular chain is preferable from the viewpoint of heat resistance, weather resistance, and acid resistance. Examples of polycarbonate include 2,2-bis(4-hydroxyphenyl)propane (aka bisphenol A), 2,2-bis(4-hydroxyphenyl)butane, and 1,1-bis(4-hydroxyphenyl). and polycarbonates derived from bisphenols such as cyclohexane, 1,1-bis(4-hydroxyphenyl)isobutane, and 1,1-bis(4-hydroxyphenyl)ethane.

The (meth)acrylic resin that can constitute the first and second resin films 3 and 4 may be a polymer mainly composed of structural units derived from methacrylic acid ester (for example, containing 50% by weight or more of this), , it is preferable that it is a copolymer in which other copolymerization components are copolymerized.

The (meth)acrylic resin may contain two or more types of structural units derived from methacrylic acid ester. Examples of methacrylic acid esters include C ₁ to _{C 4} alkyl esters of methacrylic acid such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate.

A copolymerization component that can be copolymerized with methacrylic acid ester includes acrylic acid ester. The acrylic acid ester is preferably a C ₁ to _{C 8} alkyl ester of acrylic acid such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. Specific examples of other copolymerization components include unsaturated acids such as (meth)acrylic acid; Aromatic vinyl compounds such as styrene, halogenated styrene, α-methylstyrene, and vinyl toluene; Vinyl cyan compounds such as (meth)acrylonitrile; Unsaturated acid anhydrides such as maleic anhydride and citraconic anhydride; Compounds other than acrylic acid esters that have one polymerizable carbon-carbon double bond in the molecule include unsaturated imides such as phenylmaleimide and cyclohexylmaleimide. A compound having two or more polymerizable carbon-carbon double bonds in the molecule may be used as a copolymerization component. Copolymerization components can be used individually or in combination of two or more.

The (meth)acrylic acid resin may have a ring structure in the polymer main chain because it can increase the durability of the film. The ring structure is preferably a heterocyclic structure such as a cyclic acid anhydride structure, a cyclic imide structure, or a lactone ring structure. Specific examples of the cyclic acid anhydride structure include glutaric acid anhydride structure and succinic anhydride structure, specific examples of the cyclic imide structure include glutarimide structure and succinimide structure, and specific examples of the lactone ring structure include A butyrolactone ring structure, a valerolactone ring structure, etc. are mentioned.

The (meth)acrylic resin may contain acrylic rubber particles from the viewpoint of film forming properties on the film and impact resistance of the film. Acrylic rubber particles are particles containing an elastic polymer mainly composed of acrylic acid ester as an essential component, and may have a single-layer structure substantially composed only of this elastic polymer, or may have a multi-layer structure with the elastic polymer as one layer. Examples of the elastic polymer include a crosslinked elastic copolymer that has alkyl acrylate as a main component and is copolymerized with other copolymerizable vinyl monomers and crosslinkable monomers. Examples of alkyl acrylates that are the main component of the elastic polymer include C ₁ to _{C 8} alkyl esters of acrylic acid such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. The carbon number of the alkyl group is preferably 4 or more.

Other vinyl monomers that can be copolymerized with alkyl acrylate include compounds having one polymerizable carbon-carbon double bond in the molecule, and more specifically, methacrylic acid esters such as methyl methacrylate, and aromatic vinyl compounds such as styrene. and vinyl cyan compounds such as (meth)acrylonitrile. Examples of crosslinkable monomers include crosslinkable compounds having at least two polymerizable carbon-carbon double bonds in the molecule, and more specifically, polyvalent monomers such as ethylene glycol di(meth)acrylate and butanediol di(meth)acrylate. Alkenyl esters of (meth)acrylic acid such as (meth)acrylate of alcohol and allyl (meth)acrylate, divinylbenzene, etc. are mentioned.

The content of the acrylic rubber particles is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, based on 100 parts by weight of the (meth)acrylic resin. If the content of acrylic rubber particles is too high, the surface hardness of the film may decrease, and when the film is subjected to surface treatment, the solvent resistance to the organic solvent in the surface treatment agent may decrease. Therefore, the content of acrylic rubber particles is usually 80 parts by weight or less, preferably 60 parts by weight or less, based on 100 parts by weight of the (meth)acrylic resin.

The first and second resin films 3 and 4 may contain common additives in the technical field of the present invention. Examples of additives include ultraviolet absorbers, infrared absorbers, organic dyes, pigments, inorganic pigments, antioxidants, antistatic agents, surfactants, lubricants, dispersants, heat stabilizers, etc. Examples of ultraviolet absorbers include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, triazine compounds, cyano (meth)acrylate compounds, nickel complex salts, etc.

The first and second resin films 3 and 4 may be either unstretched films or uniaxially or biaxially stretched films. The first resin film 3 and/or the second resin film 4 may be a protective film that serves to protect the polarizer 2, or may be a protective film that also has an optical function such as a retardation film to be described later. In addition, the first resin film 3 and the second resin film 4 may be the same or different films.

In addition, the first resin film 3 and/or the second resin film 4 have a hard coat layer, an anti-glare layer, an anti-reflection layer, a light diffusion layer, an anti-static layer, It may be provided with a surface treatment layer (coating layer) such as an antifouling layer or a conductive layer. The thickness of the first resin film 3 and the second resin film 4 is usually 1 to 150 ㎛, respectively, preferably 5 to 100 ㎛ (for example, 5 to 60 ㎛), more preferably 50 ㎛ or less ( For example, it may be 1 to 40 μm), and further, it may be 30 μm or less (for example, 5 to 25 μm).

In particular, in polarizers for small and medium-sized devices such as smartphones and tablet-type terminals, thin films with a thickness of 30 μm or less are often used as the first resin film 3 and/or the second resin film 4 due to the requirement for thinning. , such a polarizing plate has a weak force for suppressing the shrinkage force of the polarizer 2, and tends to have insufficient durability. Even when such a polarizing plate is used as the optical film 10, the optical film 1 equipped with the adhesive layer of the present invention has good durability.

The first and second resin films 3 and 4 can be bonded to the polarizer 2 through an adhesive layer or adhesive layer. As an adhesive for forming the adhesive layer, a water-based adhesive or an active energy ray-curable adhesive can be used.

Examples of water-based adhesives include common water-based adhesives (e.g., adhesives made of polyvinyl alcohol-based resin aqueous solutions, water-based two-component urethane-based emulsion adhesives, aldehyde compounds, epoxy compounds, melamine-based compounds, methylol compounds, isocyanate compounds, amine compounds, polyvalent metal salts, etc. crosslinking agents, etc.). Among these, a water-based adhesive made of an aqueous polyvinyl alcohol-based resin solution can be suitably used. In addition, when using a water-based adhesive, after bonding the polarizer 2 and the first and second resin films 3 and 4, it is preferable to perform a drying process to remove water contained in the water-based adhesive. do. After the drying process, a curing process may be performed, for example, at a temperature of about 20 to 45°C.

The active energy ray-curable adhesive refers to an adhesive that is cured by irradiating active energy rays such as ultraviolet rays or electron beams, and includes, for example, a curable composition containing a polymerizable compound and a photopolymerization initiator, a curable composition containing a photoreactive resin, a binder resin, and A curable composition containing a photoreactive crosslinking agent may be included, and an ultraviolet curable adhesive is preferred.

When using an active energy ray curable adhesive, after bonding the polarizer 2 and the first and second resin films 3 and 4, a drying process is performed as necessary, and then active energy rays are irradiated to form the active energy rays. A curing process is performed to harden the curable adhesive. The light source of the active energy ray is not particularly limited, but ultraviolet rays having an emission distribution in a wavelength of 400 nm or less are preferable.

As a method of bonding the polarizer 2 and the first and second resin films 3 and 4, a method of subjecting at least one of the bonding surfaces to a surface activation treatment such as saponification treatment, corona treatment, or plasma treatment, etc. can be mentioned. When resin films are bonded to both sides of the polarizer 2, the adhesive for bonding these resin films may be of the same type or may be of a different type.

The polarizers 10a and 10b may further include other films or layers. Specific examples include, in addition to the retardation film described later, a brightness enhancing film, an anti-glare film, an anti-reflection film, a diffusion film, a light-collecting film, an adhesive layer other than the adhesive layer 20, a coating layer, and a protection film. The protect film is a film used to protect the surface of the optical film 10, such as a polarizing plate, from scratches and dirt, and is used to peel and remove the optical film 1 with an adhesive layer, for example, after bonding it to a metal layer or a substrate. It is customary to do so.

A protective film usually consists of a base film and an adhesive layer laminated on it. The base film may be a thermoplastic resin, such as a polyolefin resin such as polyethylene resin or polypropylene resin; Polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polycarbonate-based resin; It can be composed of (meth)acrylic resin, etc.

[2-3] Phase difference plate

The retardation film included in the retardation plate is an optical film showing optical anisotropy as described above, and can be used for the first and second resin films 3 and 4, in addition to the thermoplastic resins exemplified above, such as polyvinyl alcohol-based Resin, polyarylate-based resin, polyimide-based resin, polyethersulfone-based resin, polyvinylidene fluoride/polymethyl methacrylate-based resin, liquid crystal polyester-based resin, ethylene-vinyl acetate copolymer saponified product, polyvinyl chloride It may be a stretched film obtained by stretching a resin film made of a resin or the like to about 1.01 to 6 times. Among these, a stretched film obtained by uniaxially stretching or biaxially stretching a polycarbonate-based resin film, cyclic olefin-based resin film, (meth)acrylic-based resin film, or cellulose-based resin film is preferable. In addition, in this specification, a zero retardation film is also included in the retardation film (however, it can also be used as a protective film). In addition, films called uniaxial retardation films, wide viewing angle retardation films, low optical modulus retardation films, etc. are also applicable as retardation films.

A zero retardation film refers to a film in which both the in-plane retardation value (R _e ) and the thickness direction retardation value (R _th ) are -15 to 15 nm. This retardation film is suitably used in IPS mode liquid crystal display devices. The in-plane retardation value (R _e ) and the thickness direction retardation value (R _th ) are preferably -10 to 10 nm together, and more preferably -5 to 5 nm together. The in-plane retardation value (R _e ) and the thickness direction retardation value (R _th ) mentioned here are values at a wavelength of 590 nm.

The in-plane retardation value (R _e ) and the thickness direction retardation value (R _th ) are each expressed by the following equations:

R _e =(n _x -n _y )×d

R _th =[(n _x +n _y )/2-n _z ]×d

It is defined as In the _{formula , n} It is the refractive index in the thickness direction (z-axis direction perpendicular to the film plane), and d is the thickness of the film.

For the zero retardation film, for example, a resin film made of polyolefin resin such as cellulose resin, linear polyolefin resin, and cyclic polyolefin resin, polyethylene terephthalate resin, or (meth)acrylic resin can be used. In particular, cellulose-based resin, polyolefin-based resin, or (meth)acrylic resin is preferably used because the retardation value is easy to control and is easy to obtain.

In addition, a film that exhibits optical anisotropy by application and orientation of a liquid crystalline compound or a film that exhibits optical anisotropy by application of an inorganic layered compound can also be used as a retardation film. Such retardation films include those called temperature-compensated retardation films, films with obliquely oriented rod-shaped liquid crystals sold under the trade name "NH Film" from JX Nippon-Nisseki Energy Co., Ltd., and those sold under the trade name "NH Film" from Fujifilm Co., Ltd. A film with obliquely oriented disc-shaped liquid crystals sold under the trade name of “WV Film”, a fully biaxially oriented film sold under the trade name of “VAC Film” from Sumitomo Chemical Co., Ltd., also from Sumitomo Chemical Co., Ltd. There are biaxially oriented films sold under the brand name “new VAC film.” Additionally, the resin film laminated on at least one side of the retardation film may be, for example, the protective film described above.

[3] Optical laminate

4 to 8 are schematic cross-sectional views showing examples of optical laminates including an optical film with an adhesive layer formed from the adhesive composition according to the present invention.

The optical laminate 5 shown in FIG. 4 includes a metal layer 30 (or a metal wiring layer 30) laminated on a substrate 40 and an optical film 1a with the adhesive layer (or an adhesive layer). It is an optical laminate laminated on the surface on the adhesive layer side of the equipped polarizing plate (1a). The optical film 1a with the adhesive layer is obtained by laminating the adhesive layer 20 on the surface of the polarizer 10a on the polarizer 2 side.

The optical laminate 6 shown in FIG. 5 consists of a metal layer 30 laminated on a substrate 40 and an adhesive layer of an optical film 1b with an adhesive layer (or a polarizing plate 1b with an adhesive layer). It is an optical laminate laminated on the side surface. The optical film with an adhesive layer (1b) is an optical film in which an adhesive layer (20) is laminated on the surface of the polarizing plate (10b) on the side of the second resin film (4).

The optical laminates 5 and 6 can be obtained by bonding the optical films 1a and 1b with an adhesive layer to the metal layer 30 laminated on the substrate 40 via the adhesive layer 20.

Examples of a method for forming the metal layer 30 on the substrate 40 include sputtering. The substrate 40 may be a transparent substrate constituting a liquid crystal cell included in the touch input element, and is preferably a glass substrate. As a material for this glass substrate, soda-lime glass, low-alkali glass, alkali-free glass, etc. can be used. The metal layer 30 may be formed on the entire surface of the substrate 40 or may be formed on a part of it.

The metal layer 30 contains at least one metal element selected from, for example, aluminum, copper, silver, iron, tin, zinc, nickel, molybdenum, chromium, tungsten, lead, and alloys containing two or more of these metals. Even the floor that does it is good. Among these, from the viewpoint of conductivity, the layer may preferably contain at least one metal element selected from aluminum, copper, silver, and gold, and from the viewpoint of conductivity and cost, it is more preferable to contain the aluminum element. It may be a layer, and more preferably a layer containing aluminum as a main component (50% by weight or more of the total metal components constituting the metal layer 30).

The metal layer 30 may be, for example, a transparent electrode layer such as ITO (tin-doped indium oxide), or may have a transparent electrode layer made of a metal oxide such as ITO together with the metal layer 30. Additionally, a metal mesh in which a thin metal wiring layer is arranged on a substrate, or a layer in which metal nanoparticles or metal nanowires are added to a binder may be used.

The preparation method of the metal layer 30 is not particularly limited, and may be a metal foil, or may be formed by vacuum deposition, sputtering, ion plating, inkjet printing, or gravure printing, but is preferably sputtering or inkjet printing. , It is a metal layer formed by gravure printing, and more preferably, it is a metal layer formed by sputtering. The thickness of the metal layer 30 is not particularly limited, but is usually 3 μm or less, preferably 1 μm or less, more preferably 0.8 μm or less, and usually 0.01 μm or more. In addition, when the metal layer 30 is a metal wiring layer (for example, a metal mesh), the line width of the metal wiring is usually 10 μm or less, preferably 5 μm or less, more preferably 3 μm or less, and usually 0.5 μm or more. am.

The optical laminate 7 shown in FIG. 6 is an optical laminate in which the adhesive layer 20 of the optical film 1 with the adhesive layer is laminated on a substrate 40.

The optical laminate 8 shown in FIG. 7 includes a resin layer 50 additionally laminated on the side of the metal layer 30 laminated on the substrate 40 (on the side opposite to the substrate 40), This is an optical laminate laminated on the surface on the adhesive layer 20 side of the optical film 1 provided with the adhesive layer. Examples of the resin forming the resin layer 50 include the resin constituting the first or second resin film exemplified above.

In the optical laminate 9 shown in FIG. 8, a plurality of metal layers 30 are laminated on a substrate 40 at predetermined intervals in the vertical and horizontal directions, and there is a gap (or gap) between the plurality of metal layers 30. Additionally, it is the same as the optical laminate 7 except that the resin layer 50 is formed (or laminated) on the surface of the metal layer 30 (on the surface opposite to the substrate 40). When the optical laminate 8 is in a form (a form in which the metal layer 30 is patterned into a predetermined shape), the metal layer 30 is, for example, a metal wiring layer (i.e., an electrode layer) of a touch input element of a touch input liquid crystal display device. It's okay too.

In the optical laminate 8, the plurality of metal layers 30 may be in full or partial contact with the adhesive layer 20, or may not be in contact. Additionally, the metal layer 30 may be a continuous film containing the above metal or alloy. Additionally, the resin layer 50 may be omitted.

After manufacturing an optical laminate by adhering the optical film (1, 1a, 1b) with an adhesive layer and the substrate 40 (glass substrate, transparent substrate, etc.) or the metal layer 30 (transparent electrode layer), were there any problems? In this case, the optical film with an adhesive layer is peeled off from the substrate 40 or the metal layer 30, and the optical film 1 with a separate adhesive layer is reattached to the substrate 40 or the metal layer 30. There are times when work becomes necessary. The optical film 1 with an adhesive layer formed from the adhesive composition according to the present invention is excellent in reworkability as dark areas or glue residues are unlikely to occur on the surface of the glass substrate or transparent electrode after peeling.

[4] Liquid crystal display device

The liquid crystal display device according to the present invention includes an optical film (1) equipped with an adhesive layer formed of the adhesive composition according to the present invention, and more typically includes the optical laminate. For this reason, the liquid crystal display device according to the present invention has excellent durability.

The liquid crystal display device according to the present invention may be a touch input type liquid crystal display device having a touch panel function. A touch input type liquid crystal display device includes a touch input element including a liquid crystal cell and a backlight. The configuration of the touch panel may be a known method (e.g., out-cell type, on-cell type, in-cell type, etc.), and the operation method of the touch panel may be a known method (e.g., a resistive type, a capacitive type (surface type capacitance type, projection). Type electrostatic capacitance method, etc.] is also good. The optical film 1 with an adhesive layer according to the present invention may be placed on the viewing side of the touch input element (liquid crystal cell), may be placed on the backlight side, or may be placed on both sides. The driving method of the liquid crystal cell may be any conventionally known method, such as TN method, VA method, IPS method, multi-domain method, OCB method, etc. In addition, in the liquid crystal display device according to the present invention, the substrate 40 included in the optical laminate may be a substrate included in the liquid crystal cell (typically a glass substrate).

Example

Hereinafter, the present invention will be described in more detail by showing examples and comparative examples, but the present invention is not limited to these examples. Hereinafter, parts and percentages indicating usage amount and content are based on weight, unless otherwise specified.

<Preparation Example 1: Preparation of (meth)acrylic resin (A-1) for adhesive layer>

A solution obtained by mixing a monomer with the composition shown in Table 1 (the values in Table 1 are parts by weight) with 81.8 parts of ethyl acetate was placed in a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer, and a stirrer. After replacing the air in the reaction vessel with nitrogen gas, the internal temperature was set to 60°C. After that, a solution in which 0.12 parts of azobisisobutyronitrile was dissolved in 10 parts of ethyl acetate was added. After maintaining the same temperature for 1 hour, while maintaining the internal temperature at 54 to 56°C, ethyl acetate was continuously added into the reaction vessel at an addition rate of 17.3 parts/Hr so that the polymer concentration was approximately 35%. After maintaining the internal temperature at 54-56°C until 12 hours have elapsed from the start of adding ethyl acetate, additional ethyl acetate was added to adjust the polymer concentration to 20%, and the (meth)acrylic resin (A-1) was added. ), an ethyl acetate solution was obtained. The weight average molecular weight (Mw) of the obtained (meth)acrylic resin (A-1) was 1.39 million, and the ratio (Mw/Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) was 5.32.

<Preparation Example 2-12: Preparation of (meth)acrylic resin (A-2 to 12) for adhesive layer>

An ethyl acetate solution of (meth)acrylic resins (A-2 to 12) was obtained in the same manner as in Production Example 1 except that the monomer composition was changed to the composition shown in Table 1 (resin concentration: 20%). The weight average molecular weights (Mw) of the obtained (meth)acrylic resins (A-2 to 12) were all in the range of 1.3 million to 1.5 million, and Mw/Mn was in the range of 4 to 6.

In the above production example, the weight average molecular weight (Mw) and number average molecular weight (Mn) were measured using four columns of "TSKgel XL" manufactured by Tosoh Corporation and "Shodex" manufactured by Showa Denko Co., Ltd. as columns in the GPC apparatus. A total of five GPC KF-802's were placed in series, using tetrahydrofuran as an eluent, under the following conditions: sample concentration of 5 mg/mL, sample introduction amount of 100 μL, temperature of 40°C, and flow rate of 1 mL/min. It was measured by standard polystyrene conversion. The conditions for obtaining the GPC emission curve were also the same.

The glass transition temperature (Tg) was measured under a nitrogen atmosphere using a differential scanning calorimeter (DSC) "EXSTAR DSC6000" manufactured by SI Nanotechnology Co., Ltd., with a temperature range of -80 to 50°C and a temperature increase rate of 10°C/ It was measured under conditions of minutes.

The composition of the monomers (the values in Table 1 are in parts by weight) in each production example are shown in Table 1.

Abbreviated names in the “Monomer Composition” column of Table 1 refer to the following monomers.

BA: Butyl acrylate (glass transition temperature of homopolymer: -54°C)

MA: Methyl acrylate (glass transition temperature of homopolymer: 10°C)

HEA: 2-hydroxyethyl acrylate

4HBA: 4-hydroxybutyl acrylate

5HPA: 5-hydroxypentyl acrylate

PEA: Phenoxyethyl acrylate

PEA2: Phenoxydiethylene glycol acrylate

BMAA: Butoxymethyl acrylamide

AA: Acrylic acid

<Examples 1 to 12, Comparative Examples 1 to 9>

(1) Preparation of adhesive composition

To the ethyl acetate solution (resin concentration: 20%) of the (meth)acrylic resin obtained in the above production example, a crosslinking agent (B) and a silane compound ( C) and ionic compound (D) were mixed, and ethyl acetate was added so that the solid content concentration was 14% to obtain an adhesive composition. The mixing amount of each compounding ingredient shown in Table 2 is the weight number of active ingredients contained in the product used if it contains a solvent, etc.

The details of each compounding component indicated by abbreviation in Table 2 are as follows.

(Cross-linking agent)

B-1: Ethyl acetate solution (solid content concentration 75%) of trimethylolpropane adduct of tolylene diisocyanate, brand name “Colonate L” obtained from Tosoh Co., Ltd.

B-2: Ethyl acetate solution (solid content concentration 75%) of trimethylolpropane adduct of xylylene diisocyanate, brand name “Takenate D-110N” obtained from Mitsui Chemicals Co., Ltd.

(Silane compound)

C-1: 1,6-bis(trimethoxysilyl)hexane, C-2: 1,8-bis(trimethoxysilyl)hexane, C-3: Silicone oligomer containing methyl group/methoxy group, Shin-Etsu Chemical Co., Ltd. Product name "X-40-9250", C-4: 1,3-bis(3'-trimethoxypropyl)urea obtained from Co., Ltd.

(ionic compound)

D-1: N-decylpyridinium bis(fluorosulfonyl)imide, D-2: Potassium bis(fluorosulfonyl)imide, D-3: Lithium bis(trifluoromethylsulfonyl)imide De, D-4: N-decylpyridinium tetra(pentafluorophenyl)borate.

(2) Production of adhesive layer

Each adhesive composition prepared in (1) above was dried using an applicator on the release-treated surface of a separate film made of a polyethylene terephthalate film to which release treatment had been performed (trade name "PLR-382051" obtained from Lintech Co., Ltd.). It was applied to a thickness of 20 ㎛ and dried at 100°C for 1 minute to produce an adhesive layer (adhesive sheet).

(3) Production of optical film (P-1) with adhesive layer

A polyvinyl alcohol film with an average degree of polymerization of about 2400, a degree of saponification of 99.9 mol%, and a thickness of 60 ㎛ (trade name “Kurare Vinylon VF-PE#6000” manufactured by Kuraray Co., Ltd.) was immersed in pure water at 37°C, followed by iodine. and potassium iodide (iodine/potassium iodide/water (weight ratio) = 0.04/1.5/100) at 30°C. After that, it was immersed in an aqueous solution containing potassium iodide and boric acid (potassium iodide/boric acid/water (weight ratio) = 12/3.6/100) at 56.5°C. After washing the film with pure water at 10°C, it was dried at 85°C to obtain a polarizer with a thickness of about 23 μm in which iodine was adsorbed and oriented on polyvinyl alcohol. Stretching was mainly carried out in the steps of iodine dyeing and boric acid treatment, and the total stretching ratio was 5.3 times.

A transparent protective film made of a triacetylcellulose film with a thickness of 25 μm (trade name “KC2UA” manufactured by Konica Minolta Opt Co., Ltd.) was bonded to one side of the obtained polarizer through an adhesive made of an aqueous solution of polyvinyl alcohol-based resin. Next, on the side opposite to the triacetylcellulose film in the polarizer, a zero retardation film made of cyclic polyolefin resin with a thickness of 23 μm (trade name “ZEONOR” manufactured by Nippon Zeon Co., Ltd.) was placed on the surface of the polarizer. A polarizing plate was manufactured by bonding using an adhesive made of an aqueous solution. Next, corona discharge treatment to improve adhesion was performed on the side of the zero retardation film opposite to the side in contact with the polarizer, and then the side (adhesive layer side) opposite to the separate film of the adhesive layer produced in (2) above. After bonding with a laminator, curing was performed for 7 days at a temperature of 23°C and a relative humidity of 65% to obtain an optical film (P-1) with an adhesive layer.

(4) Durability evaluation of optical films with adhesive layer

The optical film (P-1) with an adhesive layer prepared in (3) above was cut into a size of 300 mm It was bonded to a glass substrate or a glass substrate with ITO (tin-doped indium oxide). The obtained test piece to which the glass substrate was bonded (optical film with an adhesive layer to which the glass substrate was bonded) was pressurized in an autoclave at a temperature of 50°C and a pressure of 5 kg/cm2 (490.3 kPa) for 20 minutes. For the glass substrate, alkali-free glass brand name "Eagle XG" manufactured by Corning Corporation was used. Additionally, as a glass substrate with ITO, a 30 nm ITO layer was used on alkali-free glass (product name "Eagle

The following three types of durability tests were performed on the obtained optical laminate.

[Durability Test]

·Heat resistance test (glass substrate) maintained for 1000 hours under dry conditions at a temperature of 95°C,

·Heat resistance test maintained for 1000 hours under dry conditions at a temperature of 95℃ (glass with ITO),

· Moist and heat resistance test (glass substrate) maintained for 1000 hours in an environment with a temperature of 60°C and a relative humidity of 90%,

· Heat shock resistance (HS) test (glass substrate) in which the operation of holding for 30 minutes under dry conditions at a temperature of 85°C, and then holding for 30 minutes under dry conditions at a temperature of -40°C is one cycle, and this is repeated 1000 cycles.

The optical laminate after each test was visually observed to determine whether there were changes in appearance such as lifting, peeling, or foaming of the adhesive layer, and durability was evaluated according to the following evaluation criteria. The results are shown in Table 3.

5: No changes in appearance such as lifting, peeling, foaming, etc. are observed.

4: Appearance changes such as lifting, peeling, foaming, etc. are hardly visible.

3: Slightly noticeable changes in appearance such as lifting, peeling, foaming, etc.

2: Appearance changes such as lifting, peeling, and foaming are noticeable.

1: Appearance changes such as lifting, peeling, and foaming are significantly recognized.

(5) Evaluation of adhesive strength of optical film with adhesive layer

The optical film (P-1) with an adhesive layer produced in (3) above was cut into test pieces of 25 mm x 150 mm in size. The separator was peeled off from the test piece, and the adhesive side was adhered to the glass substrate. The obtained test piece to which the glass substrate was bonded (optical film with an adhesive layer to which the glass substrate was bonded) was pressurized in an autoclave at a temperature of 50°C and a pressure of 5 kg/cm2 (490.3 kPa) for 20 minutes. After being stored for 24 hours in an atmosphere of 23°C and 50% relative humidity, the optical film was peeled from the test piece along with the adhesive layer in a 180° direction at a speed of 300 mm/min. The average peel force during peeling is shown in Table 3 as adhesive force. When the adhesive force is 10 N or less, reworkability is excellent, and when the adhesive force is 0.5 N or more, peeling is unlikely to occur even when subjected to an impact from the edge of the polarizing plate.

[Evaluation of ITO corrosion of optical laminate]

The surface resistance (surface resistance value before test) of the ITO layer surface of the glass substrate with an ITO layer was measured with a low resistivity meter (trade name "Loresta AX" manufactured by Mitsubishi Chemical Corporation). Next, the polarizing plate with the adhesive layer prepared in (3) above was cut into a test piece of 20 mm x 40 mm in size and adhered to the ITO layer side of the glass substrate through the adhesive layer. The obtained optical laminate was stored in an oven at a temperature of 60°C and a relative humidity of 90% for 500 hours, and then peeled between the ITO layer and the adhesive layer in an atmosphere of a temperature of 23°C and a relative humidity of 50%. The surface resistance of the ITO layer after peeling (post-test surface resistance value) was measured. The resistance change rate before and after the test was calculated using the formula below and evaluated based on the following criteria. The smaller the resistance change rate, the lower the corrosiveness of ITO. The results are shown in Table 3.

Resistance change rate (%) = [(surface resistance value after test) - (surface resistance value before test)]/[surface resistance value before test] × 100

〈Evaluation criteria for ITO corrosiveness〉

○: An optical laminate with a resistance change rate of less than 50% and good ITO corrosion resistance.

×: The resistance change rate is 50% or more, and the ITO corrosiveness of the optical laminated body is poor.

(6) Evaluation of antistatic properties of optical films with adhesive layer

After peeling off the separator of the polarizing film with the obtained adhesive layer, the surface resistance value of the adhesive was measured with a surface specific resistance measuring device (“Hiresta-up MCP-HT450” (brand name) manufactured by Mitsubishi Chemical Corporation). . The measurement was conducted under the conditions of an applied voltage of 250 V and an application time of 10 seconds. If the surface resistance is 1.0×10 ¹² Ω/□ or less, good antistatic properties can be obtained.

[Gel fraction of adhesive sheet]

A method for evaluating the gel fraction of the pressure-sensitive adhesive sheet of the present invention is described. The larger the gel fraction, the more crosslinking reactions proceed in the adhesive, which can be used as a standard for crosslinking density. The gel fraction is a value measured according to (1) to (4) below.

(1) An adhesive sheet with an area of about 8 cm

(2) The bonded product obtained in (1) above is weighed, and its weight is set as Ws. Then, it is folded four times to cover the adhesive sheet, fixed with a stapler, and then weighed, and its weight is set as Wb.

(3) Place the mesh fixed with a stapler in (2) above into a glass container, add 60 mL of ethyl acetate, immerse it, and store the glass container at room temperature for 3 days.

(4) The mesh is taken out from the glass container, dried at 120°C for 24 hours, weighed, the weight is set to Wa, and the gel fraction is calculated based on the following formula.

Gel fraction (% by weight) = [{Wa-(Wb-Ws)-Wm}/(Ws-Wm)]×100

1, 1a, 1b: optical film with adhesive layer, 2: polarizer, 3: first resin film, 4: second resin film, 5, 6, 7, 8, 9: optical laminate, 10: optical film, 10a, 10b: Polarizer, 20: Adhesive layer, 30: Metal layer, 40: Substrate, 50: Resin layer.

Claims (12)

An adhesive composition containing a (meth)acrylic resin (A), a crosslinking agent (B), and a silane compound (C),
The (meth)acrylic resin (A) has the following formula (a1)

(In the formula, n represents an integer of ¹ to 4, A ¹ represents a hydrogen atom or an alkyl group, and good night)
A structural unit derived from a hydroxyl group-containing (meth)acrylate represented by and the following formula (a2)

(In the formula, m represents an integer of 5 or more, A ² represents a hydrogen atom or an alkyl group, X ² represents a methylene group which may have a substituent, and the substituents may be the same or different)
Contains a structural unit derived from a hydroxyl group-containing (meth)acrylate represented by,
The crosslinking agent (B) is a tolylene diisocyanate-based compound and/or an adduct of a tolylene diisocyanate-based compound with a polyhydric alcohol compound,
With respect to 100 parts by weight of all structural units constituting the (meth)acrylic resin, the ratio of structural units derived from the hydroxy group-containing (meth)acrylate represented by formula (a1) is 1.5 to 4.5 parts by weight, and formula (a2) ) A pressure-sensitive adhesive composition in which the proportion of structural units derived from hydroxyl group-containing (meth)acrylate represented by ) is 0.25 to 0.5 parts by weight. An adhesive composition containing a (meth)acrylic resin (A), a crosslinking agent (B), and a silane compound (C),
The (meth)acrylic resin (A) has the following formula (a1)

(In the formula, n represents an integer of ¹ to 4, A ¹ represents a hydrogen atom or an alkyl group, and good night)
A structural unit derived from a hydroxyl group-containing (meth)acrylate represented by and the following formula (a2)

(In the formula, m represents an integer of 5 or more, A ² represents a hydrogen atom or an alkyl group, X ² represents a methylene group which may have a substituent, and the substituents may be the same or different)
Contains a structural unit derived from a hydroxyl group-containing (meth)acrylate represented by,
The crosslinking agent (B) is a tolylene diisocyanate-based compound and/or an adduct of a tolylene diisocyanate-based compound with a polyhydric alcohol compound,
The ratio (weight ratio) of the structural unit derived from the hydroxyl group-containing (meth)acrylate represented by formula (a1) and the structural unit derived from the hydroxyl group-containing (meth)acrylate represented by formula (a2) is (a1) )/(a2) = 13/1 to 5/1. The (meth)acrylic resin according to claim 1 or 2, wherein the (meth)acrylic resin includes structural units derived from alkyl acrylate (a3-1) whose homopolymer glass transition temperature is less than 0°C, and the homopolymer glass transition temperature is less than 0°C. An adhesive composition comprising a structural unit derived from alkyl acrylate (a3) containing a structural unit derived from alkyl acrylate (a3-2) as described above. The composition according to claim 3, wherein the structural unit is derived from alkyl acrylate (a3-1) whose glass transition temperature of the homopolymer is less than 0°C and the component derived from alkyl acrylate (a3-2) whose glass transition temperature of the homopolymer is 0°C or higher. An adhesive composition in which the unit ratio (weight ratio) is (a3-1)/(a3-2)=20/80 to 95/5. The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the weight average molecular weight of the (meth)acrylic resin is 6.0×10 ⁵ to 2.5×10 ⁶ in terms of polystyrene. The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the ratio of the crosslinking agent (B) is 0.01 to 10 parts by weight based on 100 parts by weight of the (meth)acrylic resin (A). The method of claim 1 or 2, wherein the silane compound (C) has the following formula (c1)

(Wherein, B represents an alkanediyl group having 1 to 20 carbon atoms or a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and -CH ₂ - constituting the alkanediyl group and the alicyclic hydrocarbon group is -O- or - It may be substituted with CO-, R ¹ represents an alkyl group having 1 to 5 carbon atoms, and R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are each independently an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms. represents the flag)
An adhesive composition that is a silane compound represented by . The method of claim 7, wherein B in formula (c1) is an alkanediyl group having 1 to 10 carbon atoms, R ¹ is an alkyl group having 1 to 5 carbon atoms, and R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are each An adhesive composition that is independently an alkoxy group having 1 to 5 carbon atoms. The adhesive composition according to claim 1 or 2, wherein the ratio of the silane compound (C) is 0.01 to 10 parts by weight based on 100 parts by weight of the (meth)acrylic resin (A). The adhesive composition according to claim 1 or 2, wherein the gel fraction of the adhesive formed from the adhesive composition is 50 to 95%. The adhesive according to claim 1 or 2, wherein the adhesive layer formed of the adhesive composition is bonded to a glass substrate, and the adhesive strength of the adhesive layer after 24 hours under conditions of a temperature of 23° C. and a relative humidity of 50% is a peeling rate of 300. An adhesive composition that is 0.5 to 10 N/25 mm in mm/min. The adhesive composition according to claim 1 or 2, which is used for forming an adhesive layer laminated on an optical film.