TW201732009A - Adhesive composition - Google Patents

Abstract

The present invention provides an adhesive composition capable of forming a adhesive layer exhibiting excellent durability even under severe durability conditions. The adhesive composition comprises a (meth)acrylic resin (A), a crosslinking agent (B) and a silane compound (C), wherein the (meth) acrylic resin (A) comprises a structural unit derived from a hydroxy group-containing (meth) acrylate represented by the following formula (a1) and the following formula (a2), and the crosslinking agent (B) is an adduct of a tolylene diisocyanate compound and/or a tolylene diisocyanate compound with a polyhydric alcohol compound:.

Description

Adhesive composition

The present invention relates to an adhesive composition which is advantageous for forming an adhesive layer having excellent durability in an optical film or the like which is applied to an adhesive layer such as a liquid crystal display device.

A polarizing plate in which a transparent resin film is laminated on one surface or both surfaces of a polarizer is used as a representative optical film, and is widely used as an optical member constituting a video display device such as a liquid crystal display device. For example, an optical film of a polarizing plate is used by being bonded to another member (for example, a liquid crystal cell of a liquid crystal display device) through an adhesive layer (see Patent Document 1). Therefore, as an optical film, an optical film having an adhesive layer on which one side of an adhesive layer is provided in advance is known.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2010-229321

In recent years, liquid crystal display devices have been used in smart phones and The tablet type terminal device is continuously developed as a representative mobile device use and a vehicle-mounted device represented by a car navigation system. Because it is more likely to be exposed to a harsh environment in such applications than conventional TV applications in the home, the durability of the lifting device is a problem.

In the optical film constituting the adhesive layer such as a liquid crystal display device, durability is also required in the same manner. That is, the adhesive layer to be assembled in a liquid crystal display device or the like may be placed in an environment of high temperature or high temperature and high humidity, or alternating between high temperature and low temperature, and an optical film with an adhesive layer is required. Even in such an environment, it is possible to suppress defects such as floating, peeling, foaming of the adhesive layer, and the like which are generated at the interface between the adhesive layer and the optical member to which the adhesive layer is bonded, and it is also required that the optical characteristics are not deteriorated. . In particular, when the optical film is a polarizing plate, since a large shrinkage stress is generated in a high temperature environment, the adhesive layer is required to have higher durability than a general optical film. Since the demand for improving the durability of the above liquid crystal display device is increasing, the durability required for the adhesive layer is now very strict.

Accordingly, an object of the present invention is to provide an adhesive composition capable of forming an adhesive layer exhibiting excellent durability even under such severe durability conditions.

In order to solve the above problems, the present inventors have intensively studied the results and completed the present invention.

That is, the present invention encompasses the following contents.

[1] An adhesive composition comprising a (meth)acrylic resin (A), a crosslinking agent (B), and a decane compound (C), wherein the (meth)acrylic resin (A) is Containing a structural unit derived from a hydroxyl group-containing (meth) acrylate represented by the following formula (a1), (wherein n represents an integer of 1 to 4, A ¹ represents a hydrogen atom or an alkyl group, X ¹ represents a methylene group which may have a substituent, and when n is 2 or more, the substituents may be the same or different) And a structural unit derived from a hydroxyl group-containing (meth) acrylate represented by the following formula (a2), (wherein m represents an integer of 5 or more, A ² represents a hydrogen atom or an alkyl group, and X ² represents a methylene group which may have a substituent, and the substituents may be the same or different). The crosslinking agent (B) An adduct obtained by adding a polyhydric alcohol compound to a toluene diisocyanate compound and/or a toluene diisocyanate compound.

[2] The adhesive composition according to [1], which is derived from a hydroxyl group-containing (methyl) represented by the formula (a1) with respect to 100 parts by weight of the total structural unit constituting the (meth)acrylic resin. The ratio of the structural unit of the acrylate is from 1.5 to 4.5 parts by weight, and the ratio derived from the structural unit of the hydroxyl group-containing (meth) acrylate represented by the formula (a2) is from 0.25 to 1.0 part by weight.

[3] The adhesive composition according to [1] or [2] wherein the (meth)acrylic resin contains a structural unit derived from an alkyl acrylate (a3) derived from C The structural unit of the alkyl olefinate (a3) comprises: a structural unit derived from a homopolymer of a crystalline alkyl acrylate (a3-1) having a glass transition temperature of less than 0 ° C; and a glass derived from a homopolymer The structural unit of the alkyl acrylate (a3-2) having a temperature of 0 ° C or higher is transferred.

[4] The adhesive composition according to [3], wherein the glass transition temperature derived from the homopolymer is a structural unit of an alkyl acrylate (a3-1) which is less than 0 ° C, and is derived from the same element The ratio (weight ratio) between the structural units of the alkyl acrylate (a3-2) having a glass transition temperature of the polymer of 0 ° C or higher is (a3-1) / (a3-2) = 20 / 80 to 95 / 5.

[5] The 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 × in terms of polystyrene. 10 ⁶ .

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

[7] The adhesive composition according to any one of [1] to [6] wherein the decane compound (C) is a decane compound represented by the following formula (c1), (In the formula, 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 may be substituted -O- or -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 each independently represent an alkyl group or carbon having 1 to 5 carbon atoms. Number 1 to 5 alkoxy groups).

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

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

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

[11] The adhesive composition according to any one of [1] to [10] wherein the adhesive layer formed of the adhesive composition is bonded to a glass substrate at a temperature of 23 ° C, relative The adhesive force of the above-mentioned adhesive layer after 24 hours under the condition of a humidity of 50% was 0.5 to 10 N/25 mm at a peeling speed of 300 mm/min.

[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 having excellent durability even under severe endurance conditions.

1, 1a, 1b‧‧‧ optical film with adhesive layer

2‧‧‧ polarizer

3‧‧‧1st resin film

4‧‧‧2nd resin film

5, 6, 7, 8, 9‧‧‧ Optical laminates

10‧‧‧Optical film

10a, 10b‧‧‧ polarizing plate

20‧‧‧Adhesive layer

30‧‧‧metal layer

40‧‧‧Substrate

50‧‧‧ resin layer

Fig. 1 is a schematic cross-sectional view showing an example of an optical film with an adhesive layer formed of the adhesive composition of the present invention.

Fig. 2 is a schematic cross-sectional view showing an example of a layer structure of a polarizing plate.

Fig. 3 is a schematic cross-sectional view showing another example of the layer structure of the polarizing plate.

Fig. 4 is a schematic cross-sectional view showing an example of an optical layered body including an optical film having an adhesive layer formed of the adhesive composition of the present invention.

Fig. 5 is a schematic cross-sectional view showing an example of an optical layered body including an optical film having an adhesive layer formed of the adhesive composition of the present invention.

Fig. 6 is a schematic cross-sectional view showing another example of an optical laminate including an optical film having an adhesive layer formed of the adhesive composition of the present invention.

Fig. 7 is a schematic cross-sectional view showing another example of an optical laminate including an optical film having an adhesive layer formed of the adhesive composition of the present invention.

Fig. 8 is a schematic cross-sectional view showing another example of an optical laminate including an optical film having an adhesive layer formed of the adhesive composition of the present invention.

[1] Adhesive composition

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

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

The (meth)acrylic resin (A) is a polymer having a structural unit derived from a (meth)acrylic monomer as a main component (preferably containing 50% by weight or more). A compound or a copolymer comprising structural units derived from a hydroxyl group-containing (meth) acrylate represented by the following formulas (a1) and (a2).

(wherein n represents an integer of 1 to 4, A ¹ represents a hydrogen atom or an alkyl group, X ¹ represents a methylene group which may have a substituent, and when n is 2 or more, the substituents may be the same or different)

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

In other words, since the (meth)acrylic resin (A) of the present invention has a hydroxyalkyl group having a different carbon chain length (n and m) in the side chain, the adhesive layer formed of the adhesive composition is estimated. The crosslinking density between (meth)acrylic resins can be optimized. By optimizing the cross-linking density, an adhesive layer having excellent balance between hardness and softness (or having an optimum hardness) can be formed, so that durability can be improved and interface peeling can be effectively suppressed even in a high-temperature environment. (or float) and foaming. Moreover, since the adhesive layer can effectively alleviate the stress even if a strong contraction stress is generated, it is possible to prevent white spots caused by shrinkage of the optical film (for example, a deflecting plate). Further, by optimizing the crosslinking density, reworkability (peelability) can be improved. Further, in the present specification, the term "durability" refers to an environment in which, for example, a high temperature environment, a high temperature and high humidity environment, and a high temperature and a low temperature alternately alternate. Inferior, it is possible to suppress floating and peeling characteristics (also referred to as peeling resistance) generated at the interface between the adhesive layer and the optical member adjacent thereto, and to suppress defects such as foaming of the adhesive layer. Characteristics (also known as the case of foam resistance). Further, in the present invention, the agglomeration resistance is a property capable of suppressing aggregation damage (or breakage) of the adhesive layer.

In the formula (a1) and the formula (a2), X ¹ and X ^{2 each} represent a methylene group which may have a substituent. Examples of the substituent include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom), and an alkyl group (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and a second butyl group). a C _1-10 alkyl group such as a third butyl group, a pentyl group or a hexyl group, preferably a C _1-6 alkyl group, more preferably a C _1-3 alkyl group), a cycloalkyl group (cyclopentyl group, cyclohexyl group, etc.) , aryl [phenyl, alkylphenyl (tolyl, xylyl), etc.] aralkyl (benzyl, etc.), alkoxy (such as methoxy, ethoxy, etc. C _1-4 alkane) Oxyl), polyoxyalkylene (e.g., dioxoethyl, etc.), cycloalkoxy (e.g., C _5-10 cycloalkoxy such as cyclohexyloxy), aryloxy (e.g., phenoxy) And the like, an aralkoxy group (for example, a benzyloxy group, etc.), an alkylthio group (for example, a C _1-4 alkylthio group such as a methylthio group or an ethylthio group), or a cycloalkylthio group (for example, a cyclohexyl sulfide). An arylthio group (e.g., a thiophenoxy group), an aralkylthio group (e.g., a thiomethyl group, etc.), a fluorenyl group (e.g., an oxime group, etc.), a nitro group, a cyano group, etc. Among these, a halogen atom, an alkyl group, an alkoxy group, an aryloxy group or the like is preferred, and an alkyl group (e.g., a methyl group, an ethyl group, etc.) is preferred.

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

In the formula (a1), n represents an integer of 1 to 4, preferably an integer of 1 to 3, more preferably 2. Further, in the formula (a2), m is an integer of 5 or more (for example) An integer such as 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), particularly 5. Further, m may be an even number of 5 or more (for example, 6, 8, 10, 12, etc.), or may be an odd number of 5 or more (for example, 5, 7, 9, 11, etc.).

Specific examples of the hydroxyl group-containing (meth) acrylate (a1) include 1-hydroxymethyl (meth)acrylate, 1-hydroxyethyl (meth)acrylate, and 1-hydroxyl (meth)acrylate. 1-hydroxy C _1-8 alkyl (meth)acrylate, such as heptyl ester, 1-hydroxybutyl (meth)acrylate, 1-hydroxypentyl (meth)acrylate; 2-hydroxyethyl (meth)acrylate Ester, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxypentyl (meth)acrylate, 2-hydroxyhexyl (meth)acrylate, etc. ) 2-hydroxy C _2-9 alkyl acrylate; 3-hydroxypropyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 3-hydroxypentyl (meth) acrylate, (meth) acrylate 3-hydroxy C _3-10 alkyl (meth)acrylate such as 3-hydroxyhexyl ester or 3-hydroxyheptyl (meth)acrylate; 4-hydroxybutyl (meth)acrylate, (meth)acrylic acid 4 -Hydroxy-amyl ester, 4-hydroxyhexyl (meth)acrylate, 4-hydroxyheptyl (meth)acrylate, 4-hydroxyoctyl (meth)acrylate, 4-hydroxy C _4- (C) ₁₁ alkyl ester; 2-chloro-2-hydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, (A) Base) 2-hydroxy-3-phenoxypropyl acrylate or the like. Among these, from the viewpoint of durability, n such as 2-hydroxyethyl acrylate, 2-hydroxypropyl (meth)acrylate or 2-hydroxybutyl (meth)acrylate is a hydroxyl group containing 2 (meth) acrylate; 3-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 3-hydroxypentyl (meth)acrylate, etc. n is 3 hydroxyl group-containing (methyl) Acrylate is preferred. It is particularly preferable that the hydroxyl group-containing (meth) acrylate having n is 2, and among them, 2-hydroxyethyl (meth)acrylate is preferred.

Specific examples of the hydroxyl group-containing (meth) acrylate (a2) include 5-hydroxypentyl (meth)acrylate, 5-hydroxyhexyl (meth)acrylate, and 5-hydroxy(meth)acrylate. 5-hydroxy C _5-12 alkyl (meth)acrylate, such as heptyl ester, 5-hydroxyoctyl (meth)acrylate, 5-hydroxydecyl (meth)acrylate; 6-hydroxyl (meth)acrylate Ester, 6-hydroxyheptyl (meth)acrylate, 6-hydroxyoctyl (meth)acrylate, 6-hydroxydecyl (meth)acrylate, 6-hydroxydecyl (meth)acrylate, etc. ) 6-hydroxy C _6-13 alkyl acrylate; 7-hydroxyheptyl (meth) acrylate, 7-hydroxyoctyl (meth) acrylate, 7-hydroxy decyl (meth) acrylate, (meth) acrylate 7-hydroxy C _7-14 alkyl (meth)acrylate, such as 7-hydroxydecyl ester, 7-hydroxyundecyl (meth)acrylate; 8-hydroxyoctyl (meth)acrylate, (meth)acrylic acid 8-hydroxydecyl ester, 8-hydroxydecyl (meth)acrylate, 8-hydroxyundecyl (meth)acrylate, 8-hydroxyundecyl (meth)acrylate, 8-hydroxyl (meth)acrylate C _8-15 alkyl acrylate; (meth) acrylate, 9-hydroxy-nonyl ester, (meth) acrylate, 9-hydroxy decyl acrylate, (meth ) Acrylate, 9-hydroxy eleven ester, (meth) acrylate, 9-hydroxy dodecyl acrylate, (meth) acrylate, 9-hydroxy tridecyl acrylate, etc. (meth) acrylic acid C _9-16 alkyl esters of 9-hydroxy; 10-hydroxydecyl (meth)acrylate, 10-hydroxyundecyl (meth)acrylate, 10-hydroxydodecyl (meth)acrylate, 10-hydroxytridecyl acrylate, (meth)acrylic acid 10- 10-hydroxy C _10-17 alkyl (meth)acrylate such as hydroxytetradecyl ester; 11-hydroxyundecyl (meth)acrylate, 11-hydroxydodecyl (meth)acrylate, (meth)acrylic acid 10-hydroxy C _11-18 alkyl (meth)acrylate, such as 11-hydroxytridecyl ester, 11-hydroxytetradecyl (meth)acrylate, 11-hydroxypentadecyl (meth)acrylate; a 12-hydroxy C _12-19 alkyl (meth)acrylate such as 12-hydroxydodecyl acrylate, 12-hydroxytridecyl (meth)acrylate or 12-hydroxytetradecyl (meth)acrylate; 13-hydroxy C _13-20 alkyl (meth)acrylate, such as 13-hydroxypentadecyl (meth)acrylate, 13-hydroxytetradecyl (meth)acrylate, 13-hydroxypentadecyl (meth)acrylate ; (meth)acrylic acid 14-hydroxytetradecyl ester, (meth)acrylic acid 14-hydroxy fifteen Other (meth) acrylate, 14- hydroxy C _14-21 alkyl acrylate; (meth) acrylate, fifteen 15-hydroxy esters, (meth) acrylic acid esters and the like seventeen 15-hydroxy (meth) acrylate, 15-hydroxy C _15-22 alkyl ester and the like. Among these, from the viewpoint of durability, 5-hydroxypentyl (meth)acrylate, 5-hydroxyhexyl (meth)acrylate, 5-hydroxyheptyl (meth)acrylate, (methyl) A hydroxyl group-containing (meth) acrylate such as 5-hydroxyoctyl acrylate or 5-hydroxy decyl (meth)acrylate is preferable, and 5-hydroxypentyl (meth)acrylate is particularly preferred.

The ratio of the structural unit derived from the hydroxyl group-containing (meth) acrylate represented by the formula (a1) is preferably from 1.5 to 4.5 parts by weight based on 100 parts by weight of the total structural unit constituting the (meth)acrylic resin. The ratio of the structural unit derived from the hydroxyl group-containing (meth) acrylate represented by the formula (a2) is preferably 0.25 to 1.0 part by weight. Further, the ratio between the structural unit derived from the hydroxyl group-containing (meth) acrylate represented by the formula (a1) and the structural unit derived from the hydroxyl group-containing (meth) acrylate represented by the formula (a2) (weight) The ratio is not particularly limited as long as it is within the above range, and is preferably (a1)/(a2)=13/1 to 3/1 (for example, 11/1 to 3/1), more preferably 9/. 1 to 4/1, especially 7/1 to 5/1. When it is in the above range, it is advantageous for forming an optimum crosslinked structure, and it is possible to improve characteristics such as durability.

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

Among the alkyl acrylates (a3), the alkyl acrylate (a3-1) having a glass transition temperature (Tg) of less than 0 ° C, for example, may be exemplified by ethyl acrylate or acrylic acid. Propyl ester, n-butyl acrylate, n-amyl acrylate, n-isohexyl acrylate, n-heptyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-isodecyl acrylate, acrylic acid And a linear or branched chain alkyl acrylate having an alkyl group such as isodecyl ester or n-dodecyl acrylate having a carbon number of from 2 to 12. The alkyl acrylate (a3) may also be an alkyl acrylate (cycloalkyl acrylate) having an alicyclic structure, and is carbon-based from the viewpoint of the followability (or flexibility and adhesion) to the optical film. The alkyl acrylate having a number of 2 to 10 is preferably an alkyl acrylate having a carbon number of 3 to 8, more preferably an alkyl acrylate having a carbon number of 4 to 6, particularly preferably n-butyl acrylate. When n-butyl acrylate is used, the followability can be improved, for example, it is advantageous for peeling resistance and the like. These alkyl acrylates (a3-1) can be used singly or in combination of two or more.

Examples of the alkyl acrylate (a3-2) having a Tg of 0 ° C or more in the homopolymer include methyl acrylate, cycloalkyl acrylate (for example, cyclohexyl acrylate, isodecyl acrylate), and styrene acrylate. Ester, tert-butyl acrylate, etc., especially methyl acrylate is particularly preferred. When methyl acrylate is used, strength can be improved, for example, it is advantageous for agglomeration damage. These alkyl acrylates (a3-2) can be used individually or in combination of 2 or more types. Further, the Tg of the isomeric polymer of the alkyl acrylate can be referred to, for example, POLYMER HANDBOOK (Wiley-Interscience) and other literature values.

The ratio of the structural unit derived from the alkyl acrylate in the (meth)acrylic resin (A) is based on the durability and reworkability of the adhesive layer, and is based on the (meth)acrylic composition. 100 parts by weight of the total structural unit of the resin (A) is, for example, 40 parts by weight or more (for example, 50 to 98 parts by weight), preferably 60 parts by weight or more (for example, 70 to 95 parts by weight), more preferably 70 parts by weight or more ( For example, 80 to 90 parts by weight).

When the Tg of the homopolymer is used as the alkyl acrylate which is less than 0 ° C and the alkyl acrylate of the homopolymer has a Tg of 0 ° C or more, it is possible to have both cohesive failure resistance and followability (foam resistance). And peeling resistance) and can improve the durability of dimensional changes of optical films such as polarizing plates.

The structural unit derived from the homopolymer has a glass transition temperature of alkyl acrylate (a3-1) of less than 0 ° C and a structural unit derived from an alkyl acrylate (a3-2) having a glass transition temperature of 0 ° C or higher. The ratio (weight ratio) between (a3-1) / (a3-2) = 20/80 to 95/5 (for example, 30/70 to 90/10), preferably 40/60 to 85/15, More preferably 55/45 to 75/25. When it is in the above range, durability can be further improved. The higher the ratio of the structural unit derived from the alkyl acrylate (a3-1) having a glass transition temperature of less than 0 ° C, the higher the followability. When the ratio of the structural unit derived from the alkyl acrylate (a3-2) having a glass transition temperature of 0 ° C or more is increased, the aggregation resistance is also improved.

The alkyl acrylate (a4) having a substituent is, for example, an alkyl acrylate having a substituent (the hydrogen atom of the alkyl group is substituted by a substituent) introduced into the alkyl group in the alkyl acrylate (a3-1). The substituent may be, for example, an aryl group (phenyl group or the like), an aryloxy group (phenoxy group), an alkoxy group (e.g., a methoxy group, an ethoxy group, etc.). Examples of the alkyl acrylate (a3-3) having a substituent include an alkoxyalkyl acrylate (for example, 2-methoxyethyl acrylate or ethoxymethyl acrylate) and an aryloxyalkyl acrylate. (e.g., phenoxyethyl acrylate or the like), aryloxy polyalkylene glycol monoacrylate, polyalkylene glycol monoacrylate, and the like. These alkyl acrylates (a3-3) can be used individually or in combination of 2 or more types. By containing an alkyl acrylate containing an aromatic ring such as an aryl group or an aryloxy group, white spots generated by the polarizing plate can be improved in the durability test. Further, the alkylene group of the aryloxy polyalkylene glycol monoacrylate and the polyalkylene glycol monoacrylate may be, for example, a C _1-6 alkylene group such as a methylene group, an exoethyl group or a propyl group. From the viewpoint of durability of the adhesive layer formed of the adhesive composition, the repeating unit of the oxygen-extended alkyl group may be, for example, 2 to 7, preferably 2 to 5 (e.g., ethyl or the like). Especially 2). In the present invention, since the (meth)acrylic resin (A) and the crosslinking agent (B) described later are contained in the adhesive composition, an optimum crosslinked structure (or crosslinking density) can be formed, so even oxygen stretching The alkyl group has a small number of repeating units and can also exhibit good reworkability. Specific examples thereof include phenoxy diethylene glycol acrylate, phenoxy a C _1-3 alkoxy glycol two to seven - acrylate, diethylene glycol monoacrylate such as two to seven C _{1- 3} alkanediol-monoacrylate, and the like.

The ratio of the structural unit derived from the alkyl acrylate containing a substituent is, for example, 0 to 30 parts by weight (for example, 1 to 25 parts by weight) per 100 parts by weight of the total structural unit constituting the (meth)acrylic resin (A). It is preferably from 3 to 20 parts by weight, more preferably from 5 to 15 parts by weight.

The (meth)acrylic resin (A) contains, in addition to the hydroxyl group-containing (meth) acrylates (a1) and (a2), alkyl acrylate (a3), and substituted groups. In addition to the structural unit of the alkyl acrylate (a4), it is also possible to contain a structural unit derived from the other monomer (a5). Other single systems can be used alone or in combination of two or more. Examples of the other monomer (a5) include a monomer (a5-1) having a polar functional group other than a hydroxyl group, an acrylamide monomer (a5-2), and a methacrylate (methacrylate). (a5-3), a methacrylamide amine monomer (a5-4), a styrene monomer (a5-5), a vinyl monomer (a5-6), and a plurality of molecules (a) a monomer of a acrylonitrile group (a5-7) or the like.

The monomer (a5-1) having a polar functional group other than a hydroxyl group may, for example, be a (meth) acrylate having a substituent such as a carboxyl group, a substituted or unsubstituted amino group or a heterocyclic group such as an epoxy group. Specific examples thereof include propylene decylmorpholine, vinyl caprolactam, N-vinyl-2-pyrrolidone, vinyl pyridine, tetrahydrofurfuryl (meth) acrylate, and caprolactone modification. a monomer having a heterocyclic group such as tetrahydrofurfuryl acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, glycidyl (meth)acrylate or 2,5-dihydrofuran; a monomer having a substituted or unsubstituted amine group such as aminoethyl acrylate, N,N-dimethylaminoethyl (meth)acrylate, or dimethylaminopropyl (meth)acrylate; (Meth)acrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, carboxyalkyl (meth)acrylate (for example, carboxyethyl (meth)acrylate, (methyl) A monomer having a carboxyl group such as carboxypentyl acrylate. These single systems can be used singly or in combination of two or more. Moreover, from the viewpoint of preventing the peeling property of the separation membrane which can be laminated on the pressure-sensitive adhesive layer from being lowered, it is preferable that the structural unit derived from the monomer having an amine group is not contained. In addition, the term "substantially no content" is less than 1.0 part by weight based on 100 parts by weight of the total structural unit constituting the (meth)acrylic resin (A).

In the present invention, since it is not contained in a structural unit derived from a monomer having a carboxyl group (a structural unit derived from a carboxyl group-containing (meth) acrylate) which is considered to increase corrosiveness of ITO, it exhibits high durability. Sexuality, so it can have both durability and ITO corrosion resistance.

On the other hand, when a structural unit derived from a monomer having a carboxyl group [derived from a structural unit of a carboxyl group-containing (meth) acrylate] is contained, durability can be further improved. In the present invention, since the durability can be effectively improved even if the ratio of the structural unit derived from the carboxyl group-containing (meth) acrylate is small, the durability can be improved while suppressing ITO corrosion.

The ratio of the structural unit derived from the carboxyl group-containing (meth) acrylate is, for example, 5.0 parts by weight or less (for example, 0 to 3 parts by weight), preferably 100 parts by weight of the structural unit derived from (meth) acrylate. It is 1.0 part by weight or less (e.g., 0 to 0.8 part by weight), more preferably 0.5 part by weight or less (e.g., 0.001 to 0.5 part by weight), still more preferably 0.3 part by weight or less (e.g., 0.005 to 0.3 part by weight), particularly 0.2. It is below the weight part (for example, 0.01 to 0.2 part by weight), especially 0.15 part by weight or less (for example, 0.05 to 0.15 part by weight). When it is less than or equal to the upper limit, ITO corrosion resistance can be suppressed, and when it is at least the lower limit value, durability can be improved.

Examples of the acrylamide-based monomer (a5-2) include N-methylol acrylamide, N-(2-hydroxyethyl) acrylamide, and N-(3-hydroxypropyl) propylene oxime. Amine, N-(4-hydroxybutyl) acrylamide, N-(5-hydroxypentyl) acrylamide, N-(6-hydroxyhexyl) acrylamide, N,N-dimethyl decylamine , N,N-diethyl acrylamide, N-isopropyl acrylamide, N-(3-dimethylaminopropyl) acrylamide, N-(1,1-dimethyl-3- Side oxybutyl) acrylamide, N-[2-(2- side Oxy-1-imidazolidinyl)ethyl]propenylamine, 2-propenylamino-2-methyl-1-propanesulfonic acid, N-(methoxymethyl)propenylamine, N- (ethoxymethyl) acrylamide, N-(propyloxymethyl) acrylamide, N-(1-methylethoxymethyl) acrylamide, N-(1-methylpropoxy) Methyl) acrylamide, N-(2-methylpropoxymethyl) acrylamide [alias: N-(isobutoxymethyl) acrylamide], N-(butoxymethyl) Acrylamide, N-(1,1-dimethylethoxymethyl)propenylamine, N-(2-methoxyethyl)propenylamine, N-(2-ethoxyethyl Acrylamide, N-(2-propoxyethyl)propenylamine, N-[2-(1-methylethoxy)ethyl]propenylamine, N-[2-(1-A Propyloxy)ethyl]propenylamine, N-[2-(2-methylpropoxy)ethyl]propenylamine [alias: N-(2-isobutoxyethyl) acrylamide ], N-(2-butoxyethyl) acrylamide, N-[2-(1,1-dimethylethoxy)ethyl]acrylamide, and the like. Among these, N-(methoxymethyl) acrylamide, N-(ethoxymethyl) acrylamide, N-(propoxymethyl) acrylamide, N-(butoxy Methyl) acrylamide, N-(2-methylpropoxymethyl) acrylamide, etc. are preferred.

Examples of the methacrylic acid ester (a5-3) include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, and n-octyl methacrylate. a linear alkyl methacrylate such as an ester or a lauryl methacrylate; a branched chain of methacrylic acid such as isobutyl methacrylate, 2-ethylhexyl methacrylate or isooctyl methacrylate; Alkyl ester; isodecyl methacrylate, cyclohexyl methacrylate, dicyclopentyl methacrylate, cyclododecan methacrylate, methylcyclohexyl methacrylate, trimethylcyclohexyl methacrylate Methyl esters such as ester, butylcyclohexyl methacrylate, cyclohexyl phenyl methacrylate Mono or dicycloalkyl acrylate; alkoxyalkyl methacrylate such as 2-methoxyethyl methacrylate or ethoxymethyl methacrylate; methacrylic acid aryl methacrylate Alkyl esters and the like.

The methacrylamide-based monomer (a5-4) may, for example, be a methacrylamide-based monomer corresponding to the acrylamide-based monomer described in (a5-2).

Examples of the styrene monomer (a5-5) include styrene; methyl styrene, dimethyl styrene, trimethylstyrene, ethyl styrene, diethyl styrene, and triethyl. Alkyl styrenes such as styrene, propyl styrene, butyl styrene, hexyl styrene, heptyl styrene, octyl styrene; fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, Halogenated styrene such as iodine styrene; nitrostyrene; ethoxylated styrene; methoxystyrene; divinylbenzene.

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 chloride; a halogenated ethylene such as vinyl bromide; a vinylidene halide such as vinylidene chloride; a nitrogen-containing aromatic vinyl such as vinylpyridine, vinylpyrrolidone or vinylcarbazole; butadiene, isoprene, and chlorine A conjugated diene monomer such as butadiene; an unsaturated nitrile such as acrylonitrile or methacrylonitrile; and the like.

Examples of the monomer (a5-7) having a plurality of (meth) acrylonitrile groups in the molecule include 1,4-butanediol di(meth)acrylate and 1,6-hexanediol. (Meth) acrylate, 1,9-nonanediol di(meth) acrylate, ethylene glycol di(meth) acrylate, diethylene glycol di(meth) acrylate a monomer having two (meth) acrylonitrile groups in the molecule such as ester, tetraethylene glycol di(meth) acrylate, tripropylene glycol di(meth) acrylate, etc.; trimethylolpropane tris(methyl) A monomer having three (meth) acrylonitrile groups in the molecule, such as an acrylate.

Further, from the viewpoint of reworkability of the adhesive layer, the (meth)acrylic resin (A) is derived from methacrylate (meth) (a5-3), methacrylamide. The ratio (or content) of the structural unit of the methacrylic monomer such as the monomer (a5-4) is preferably small. That is, the ratio of the structural unit is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, and particularly 1 part by weight, based on 100 parts by weight of the total structural unit constituting the (meth)acrylic resin (A). The following.

Further, the ratio of the structural unit derived from the other monomer (a5) is, for example, 0 to 20 parts by weight, preferably 100 parts by weight, based on 100 parts by weight of the total structural unit constituting the (meth)acrylic resin (A). 0 to 10 parts by weight (e.g., 0.001 to 10 parts by weight), more preferably 0 to 5 parts by weight (e.g., 0.01 to 3 parts by weight).

(meth)acrylic resin (A), which has a weight average molecular weight (Mw) in terms of standard polystyrene obtained 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 ) The scope. When Mw is at most the upper limit, it is advantageous from the viewpoint of coating properties when the adhesive composition is applied to a substrate, and when Mw is at or below the lower limit, it is advantageous for enhancing the adhesion of the adhesive layer to the optical layer. The follow-up of the dimensional change of the film. The molecular weight distribution expressed by the ratio of the weight average molecular weight Mw to the number average molecular weight Mn (Mw/Mn) is usually from 2 to 10, preferably from 3 to 8, more preferably from 4 to 6.

Further, the Mw of the (meth)acrylic resin (A) on the GPC discharge curve is preferably a single peak in the range of 1.0 × 10 ³ to 2.5 × 10 ⁶ . When the (meth)acrylic resin (A) having the number of peaks of 1 is used, it is advantageous for improving the durability of the pressure-sensitive adhesive layer.

In the above range of the obtained discharge curve, the phrase "having a single peak" means that there is only one maximum value in the range of Mw 1.0 × 10 ³ to 2.5 × 10 ⁶ . In the present specification, a peak having an S/N ratio of 30 or more in the GPC discharge curve is defined as a peak. In addition, the number of peaks of the GPC discharge curve and the Mw and Mn of the (meth)acrylic resin (A) can be determined by the GPC measurement conditions described in the examples.

When the (meth)acrylic resin (A) is dissolved in ethyl acetate and forms a solution having a concentration of 20% by weight, its viscosity at 25 ° C is 20 Pa. The following is better, from 0.1 to 7 Pa. s is better. When the viscosity is in this range, it is advantageous from the viewpoint of coating properties when the adhesive composition is applied to a substrate. Also, the viscosity can be measured by a Brookfield viscometer.

The glass transition temperature (Tg) of the (meth)acrylic resin (A) may be, for example, -60 to 0 ° C (for example, -50 to -10 ° C), preferably -50 to -20 ° C, more preferably -40 to -20 ° C (eg -40 to -25 ° C). In this range, it is advantageous for improving durability. Further, the glass transition temperature can be measured by a differential scanning calorimeter (DSC).

The (meth)acrylic resin (A) can be polymerized by, for example, solution A known method such as a legal, bulk polymerization method, suspension polymerization method, or emulsion polymerization method is used, and particularly a solution polymerization method is preferred. Examples of the solution polymerization method include mixing a monomer and an organic solvent, adding a thermal polymerization initiator under a nitrogen atmosphere, and stirring at a temperature of about 40 to 90 ° C (preferably 50 to 80 ° C). The method to about 15 hours. In order to control the reaction, a monomer and a thermal polymerization initiator may also be continuously or intermittently added during the polymerization. The monomer and the hot starter may also be in a state of being added to an organic solvent.

As the polymerization initiator, a thermal polymerization initiator, a photopolymerization initiator, or the like can be used. The photopolymerization initiator may, for example, be 4-(2-hydroxyethoxy)phenyl (2-hydroxy-2-propyl) ketone or the like. Examples of the thermal polymerization initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), and 1,1'-azobis (ring). Hexane-1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxy Azo compounds such as valeronitrile, dimethyl-2,2'-azobis(2-methylpropionate), 2,2'-azobis(2-hydroxymethylpropionitrile) Peroxidic lauryl hydrazine, tert-butyl hydroperoxide, benzammonium peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, peroxydicarbonate Organic peroxides such as propyl ester, tert-butyl peroxy neodecanoate, tert-butyl peroxytrimethylacetate, peroxidized (3,5,5-trimethylhexyl); potassium persulfate An inorganic peroxide such as ammonium persulfate or hydrogen peroxide. Further, a redox initiator such as a 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 of the monomers constituting the (meth)acrylic resin. Polymerization of (meth)acrylic resin, also by active energy A polymerization method by a measuring line (for example, ultraviolet rays).

Examples of the organic solvent include aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; and aliphatic alcohols such as propanol and isopropanol; acetone and methyl ethyl Ketones such as ketones and methyl isobutyl ketones.

[1-2] Crosslinking agent (B)

The adhesive composition contains a crosslinking agent (B). The crosslinking agent (B) is reacted with a hydroxyl group-containing polar functional group in the (meth)acrylic resin (A).

The crosslinking agent (B) is an addic acid compound obtained by adding a polyhydric alcohol compound (for example, glycerol, trimethylolpropane, etc.) to a toluene diisocyanate type compound and / or a toluene diisocyanate type compound. Examples of the toluene diisocyanate-based compound include monomethylbenzene diisocyanate such as 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, and 3,5-toluene diisocyanate. In the present invention, the OH group (hydroxyl group) and the crosslinking agent (B) of the hydroxyalkyl group having different carbon chain lengths (n and m) introduced into the side chain of the (meth)acrylic resin (A) The reaction is formed to form a crosslinked structure which is advantageous for durability and reworkability. In particular, since the crosslinking agent (B) is composed of the toluene diisocyanate compound and/or the toluene diisocyanate compound polyol compound, it is estimated that the strength and flexibility (flexibility) balance can be improved. The crosslinked structure can further improve durability. That is, not only in the case of application to a glass substrate, but also in the case of application (layering) on an ITO substrate, high durability can be exhibited. Further, since the crosslinking agent (B) is an isocyanate compound, the crosslinking rate and the usable time of the adhesive composition are considered. In terms of it, it is also beneficial.

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

[1-3] decane compound (C)

The adhesive composition contains a decane compound (C). By containing the decane compound (C), the adhesion (or adhesion) of the adhesive layer, the metal layer, the transparent electrode, the glass substrate, and the like can be improved. The decane compound (C) may be a decane compound which can be bonded to a reactive group (for example, an OH group of a hydroxyl group) of the (meth)acrylic resin (A), and examples thereof include vinyl trimethoxy decane. , vinyl triethoxy decane, vinyl ginseng (2-methoxyethoxy) decane, 3-glycidoxy propyl trimethoxy decane, 3-glycidoxy propyl triethoxy decane , 3-glycidoxypropylmethyldimethoxydecane, 3-glycidoxypropylethoxydimethyl decane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxy Decane, 3-chloropropylmethyldimethoxydecane, 3-chloropropyltrimethoxydecane, 3-methylpropenyloxypropyltrimethoxydecane, 3-hydrothiopropyltrimethoxy Decane, and 1,3-bis(3'-trimethoxypropyl)urea.

Further, the decane compound (C) may be a polyoxo-oxygen oligomer type compound, and when the polyfluorene oxide oligomer is described by a combination of monomers, for example, 3-hydrothiopropyl di or Trimethoxydecane-tetramethoxydecane Oligomer, 3-hydrothiomethyldi or trimethoxydecane-tetraethoxydecane oligomer, 3-hydrothiopropyldi or triethoxydecane-tetramethoxydecane oligomer a thiol-alkyl group-containing oligomer such as 3-hydrothiomethyldi or triethoxydecane-tetraethoxydecane oligomer; or a thiol-containing alkyl group-containing oligomer The thiolalkyl group is replaced with an oligomer obtained by other substituents [3-glycidoxypropyl group, (meth)acryloxypropyl group, vinyl group, amine group, etc.].

The decane compound (C) is preferably a decane compound represented by the following formula (c1). When the adhesive composition contains a decane compound represented by the following formula (c1), the adhesion (or adhesion) can be further improved, so that an adhesive layer having excellent peeling resistance can be formed. Moreover, the adhesive layer also has excellent reworkability. In particular, even when the adhesive layer is applied to a transparent electrode (for example, an ITO substrate or the like) in a high-temperature environment, the adhesion (or adhesion) can be maintained and high durability can be exhibited.

(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 also substituted with - O- or -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 each independently represent an alkyl group or a carbon number of 1 to 5 carbon atoms. 1 to 5 alkoxy groups)

In the formula (c1), B represents a methylene group, an exoethyl group, a trimethylene group, a tetramethylene group, a hexamethylene group, a hepethylene group, an octamethylene group or the like having a carbon number of 1 to 20 a cyclobutyl group (for example, a 1,2-cyclopentene butyl group), a cyclopentyl group (for example, a 1,2-cyclopentyl group, a cyclohexyl group (for example, 1,2-extended cyclohexyl), an exocyclic ring) a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms such as a group (for example, 1,2-cyclooctyl group); or -CH ₂ - constituting the alkanediyl group and the aforementioned alicyclic hydrocarbon group is substituted with -O- or a group of -CO-. Preferred B is an alkanediyl group having 1 to 10 carbon atoms. R ¹ represents a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a second butyl group, and a third butyl group. An alkyl group having 1 to 5 carbon atoms such as a pentyl group, and R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are each independently and represent an alkyl group having 1 to 5 carbon atoms as exemplified in the above R ¹ ; or methoxy Alkoxy group having 1 to 5 carbon atoms, such as a ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a second butoxy group or a third butoxy group. Preferred R ² and R ³ R ⁴ , R ⁵ and R ⁶ are alkoxy groups having 1 to 5 carbon atoms. These decane compounds (C) can be used singly or in combination of two or more.

Specific examples of the decane compound (c1) include (trimethoxyindenyl)methane, 1,2-bis(trimethoxyindenyl)ethane, and 1,2-bis(triethoxyindenyl). Ethane, 1,3-bis(trimethoxyindenyl)propane, 1,3-bis(triethoxyindenyl)propane, 1,4-bis(trimethoxydecyl)butane, 1,4 - bis(triethoxyindenyl)butane, 1,5-bis(trimethoxydecyl)pentane, 1,5-bis(triethoxydecyl)pentane, 1,6-bis ( Trimethoxydecyl)hexane, 1,6-bis(triethoxyindenyl)hexane, 1,6-bis(tripropoxydecyl)hexane, 1,8-bis(trimethoxy) Bis(tri-C _1-5 alkoxyfluorene) such as decyl, octane, 1,8-bis(triethoxyindenyl)octane, 1,8-bis(tripropoxydecyl)octane C) _1-10 alkane; bis(dimethoxymethylindenyl)methane, 1,2-bis(dimethoxymethylindenyl)ethane, 1,2-bis(dimethoxyethyl) Ethylene, 1,4-bis(dimethoxymethylindenyl)butane, 1,4-bis(dimethoxyethylindenyl)butane, 1,6-double (two Methoxymethylmercapto)hexane, 1,6-bis(dimethoxyethylindenyl)hexane, 1,8-bis(dimethoxymethylindenyl)octane, 1,8 - bis(dimethoxyethylindenyl)octane Equivalent bis(di-C _1-5 alkoxy C _1-5 alkyl fluorenyl) C _1-10 alkane; 1,6-bis(methoxydimethylmercapto)hexane, 1,8-double A bis(mono C _1-5 alkoxy-di C _1-5 alkyl fluorenyl) C _1-10 alkane such as (methoxy dimethyl fluorenyl) octane. Among these, 1,2-bis(trimethoxyindenyl)ethane, 1,3-bis(trimethoxyindenyl)propane, 1,4-bis(trimethoxydecyl)butane, Double (three C) of 1,5-bis(trimethoxyindenyl)pentane, 1,6-bis(trimethoxydecyl)hexane, 1,8-bis(trimethoxyindenyl)octane, etc. _1-3 alkoxyfluorenyl) C _1-10 alkane is preferred, and 1,6-bis(trimethoxyindenyl)hexane and 1,8-bis(trimethoxyindenyl)octane are particularly preferred. .

The ratio of the decane compound (C) is, for example, 0.01 to 10 parts by weight (for example, 0.03 to 5 parts by weight), preferably 0.05 to 3 parts by weight, more preferably 100 parts by weight based on the (meth)acrylic resin (A). It is 0.1 to 1 part by weight (for example, 0.2 to 0.5 part by weight). When it is less than the upper limit, it is advantageous for suppressing the bleeding of the decane compound (C) from the adhesive layer, and when it is at least the lower limit value, the adhesive layer, the adhesion to the metal layer, the glass substrate, or the like (or adhesion) Lifting becomes easy, and it is advantageous for improving peeling resistance and the like.

[1-4]Antistatic agent

The adhesive composition may further contain an antistatic agent. By containing an antistatic agent, the antistatic property of the adhesive can be improved (for example, defects caused by static electricity generated when the release film or the protective film is peeled off) can be suppressed. As the antistatic agent, a conventional one may be mentioned, and an ionic antistatic agent is preferred. Examples of the cationic component constituting the ionic antistatic agent include organic cations and inorganic cations. Examples of the organic cation include a pyridinium cation, an imidazolium cation, an ammonium cation, a phosphonium cation, and a phosphonium cation. Examples of the inorganic cation include an alkali metal cation such as a lithium cation, a potassium cation, a sodium cation or a phosphonium cation, an alkaline earth metal cation such as a magnesium cation or a calcium cation, and the like. The anion component constituting the ionic antistatic agent may be any of an inorganic anion and an organic anion, and is preferably an anion component containing a fluorine atom from the viewpoint of having excellent antistatic properties. Examples of the anion component containing a fluorine atom include a hexafluorophosphate anion (PF _6- ), a bis(trifluoromethanesulfonyl)imide anion [(CF ₃ SO ₂ ) ₂ N-], and a bis (fluorine). Sulfhydryl)imine anion [(FSO ₂ ) ₂ N-], tetrakis(pentafluorophenyl)borate anion [(C ₆ F ₅ ) ₄ B-], and the like. These antistatic agents can be used singly or in combination of two or more. In particular, it is a bis(trifluoromethanesulfonyl)imide anion [(CF ₃ SO ₂ ) ₂ N-], a bis(fluorosulfonyl)imide anion [(FSO ₂ ) ₂ N-], four (five) A fluorophenyl)borate anion [(C ₆ F ₅ ) ₄ B-] is preferred.

From the viewpoint of excellent stability against time in the antistatic property of the adhesive composition, an ionic antistatic agent which is solid at room temperature is preferred.

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

[1-5] Other ingredients

The adhesive composition can contain or contain two or more kinds of solvents, a crosslinking catalyst, an ultraviolet absorber, a weathering stabilizer, a tackifier, a plasticizer, a softener, a dye, a pigment, an inorganic filler, and the like. An additive such as light-scattering fine particles. Also, for the preparation of the adhesive composition It is also useful to form an adhesive layer by forming an ultraviolet curable compound, and then irradiating with ultraviolet rays to form a harder adhesive layer. Examples of the crosslinking catalyst include hexamethylenediamine, ethylenediamine, polyethylenimine, hexamethylenetetramine, diethylenetriamine, triethylenetetramine, and isophoronediamine. An amine compound such as trimethylenediamine, a polyamine resin, or a melamine resin.

The adhesive composition can contain a rust preventive agent from the viewpoint of improving the metal corrosion resistance of the adhesive layer. Examples of the rust inhibitor include a triazole compound such as a benzotriazole compound; a thiazole compound such as a benzothiazole compound; an imidazole compound such as a benzylimidazole compound; and an imidazoline compound; Quinoline compound; pyridine compound; pyrimidine compound; lanthanide compound; amine compound; urea compound; sodium benzoate; benzyl sulfide compound; di-second butyl sulfide; Kea and others.

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

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

Fig. 1 is a schematic cross-sectional view showing an example of an optical film with an adhesive layer formed of the adhesive composition of the present invention. The optical film 1 with an adhesive layer shown in Fig. 1 is an optical film 10 and an optical film in which an adhesive layer 20 is laminated on one surface of the optical film. The adhesive layer 20 is usually laminated directly on the surface of the optical film 10. Further, the adhesive layer 20 may be laminated on both surfaces of the optical film 10.

When the adhesive layer 20 is laminated on the surface of the optical film 10, the 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 ( For example, plasma treatment, corona treatment, etc. are preferred, and corona treatment is particularly preferred.

As shown in FIG. 2, when the polarizing plate is protected, the adhesive layer 20 is usually laminated (preferably directly laminated) on the surface of the polarizing plate, that is, laminated on the polarizing film 2 and the first resin film. 3 is the opposite side. 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 either of the first and second resin films 3 and 4, or may be laminated on both sides. The outer surface.

An antistatic layer may be additionally provided between the optical film 10 and the adhesive layer 20. As the antistatic layer, a lanthanoid material such as polyoxyalkylene oxide, an inorganic metal material such as tin-doped indium oxide or tin-doped cerium oxide, or an organic high such as polythiophene, polystyrene sulfonic acid or polyaniline can be used. Molecular material.

The optical film 1 with an adhesive layer may also include a separation film (release film) laminated on the outer surface of the adhesive layer 20. The separation membrane is usually peeled off during use of the adhesive layer 20 (for example, when laminated on a transparent conductive electrode and a glass substrate). The separation membrane may be, for example, a surface on which the adhesive layer 20 is formed of a film composed of various resins such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, or polyarylate. A mold release processor such as a polyoxygen treatment is performed.

The optical film 1 with an adhesive layer can be obtained by dissolving or dispersing the components constituting the above-mentioned adhesive composition in a solvent. The adhesive composition of the solvent is obtained by applying it to the surface of the optical film 10 and drying it to form the adhesive layer 20. Further, the optical film 1 with the adhesive layer can also be laminated (transferred) on the optical film by forming the adhesive layer 20 in the same manner as described above on the release-treated surface of the separation film. 10 to get the surface.

The thickness of the adhesive layer is usually from 2 to 40 μm, preferably from 5 to 30 μm, more preferably from the viewpoint of durability of the optical film with the adhesive layer and reworkability of the optical film with the adhesive layer. 10 to 25 μm. When it is less than the upper limit, the adhesive layer has a good followability (or followability) to the dimensional change of the optical film, and when it is at least the lower limit, the reworkability becomes good.

The adhesive layer is preferably one which exhibits a storage elastic modulus of 0.1 to 5 MPa in a temperature range of 23 to 80 °C. Thereby, the durability of the optical film with the adhesive layer can be more effectively improved. The phrase "displaying a storage elastic modulus of 0.1 to 5 MPa in a temperature range of 23 to 80 ° C" means that the storage elastic modulus is a value within the above range at any temperature within the range. Since the storage elastic modulus generally decreases as the temperature rises, as long as the storage elastic modulus at 23 ° C and 80 ° C is within the above range, it can be assumed that the storage elastic modulus in the above range can be exhibited at the temperature in the range. number. The storage elastic modulus of the adhesive layer can be measured using a commercially available viscoelasticity measuring device such as a viscoelasticity measuring device "DYNAMIC ANALYZER RDA II" manufactured by REOMETRIC.

The gel fraction can be used as an indicator of the crosslink density. Because the adhesive layer formed by the adhesive composition of the present invention is It has a predetermined crosslink density, so a predetermined gel fraction is displayed. That is, the gel fraction of the adhesive layer may be, for example, 50 to 95% by weight (for example, 55 to 93% by weight), preferably 60 to 90% by weight (for example, 65 to 90% by weight), more preferably It is 70 to 85% by weight (for example, 80 to 85% by weight). When the gel fraction is at least the lower limit value, it is advantageous for the foaming resistance (coagulation resistance) and reworkability of the adhesive layer, and when the gel fraction is equal to or less than the upper limit, it is advantageous for peeling resistance. . Further, the gel fraction can be measured by the method described in the examples.

The adhesive layer formed by the adhesive composition of the present invention has a predetermined adhesive force. That is, the adhesive layer is bonded to the glass substrate, and the adhesive force of the adhesive layer after 24 hours at a temperature of 23 ° C and a relative humidity of 50% is, for example, at a peeling speed of 300 mm/min. It is from 0.5 to 25 N (for example, from 0.5 to 20 N), preferably from 0.5 to 10 N (for example, from 1 to 10 N), more preferably from 1 to 8 N. When the adhesive force is at least the lower limit value, the adhesiveness (or adhesion) is improved, and the peeling resistance and the like are advantageous. When the adhesive force is equal to or less than the upper limit value, reworkability is advantageous. Further, the adhesion can be measured by the method described in the examples.

[2-1] Optical film

The optical film 10 constituting the optical film 1 with an adhesive layer may be various optical films (films having optical characteristics) that can be incorporated in an image display device such as a liquid crystal display device. The optical film 10 may have a single layer structure (for example, an optical functional film such as a polarizer, a retardation film, a brightness enhancement film, an anti-glare film, an anti-reflection film, a diffusion film, or a light-concentrating film), or may have a multilayer structure. (for example, polarizing plate, phase difference plate, etc.). Optical film 10 is polarized A plate, a polarizer, a phase difference plate or a retardation film is preferred, and a polarizing plate or a polarizer is particularly preferred. In the present specification, the optical film means a film for realizing a function of image display (display screen or the like) (for example, a film that achieves a function of enhancing the sharpness of an image). In the present specification, the polarizing plate means that a resin film or a resin layer is laminated on at least one surface of the polarizing plate, and the phase difference plate means that a resin film or a resin layer is laminated on the retardation film. At least one side of the building.

[2-2] Polarizer

2 and 3 are schematic cross-sectional views showing an example of a layer structure of a polarizing plate. In the polarizing plate 10a shown in Fig. 2, the first resin film 3 is laminated (or laminated) on one surface of the polarizing film 2 to protect the polarizing plate, and the polarizing plate 10b shown in Fig. 3 is used. Further, the second resin film 4 is laminated (or laminated) on the other surface of the polarizer 2 to protect the polarizing plate. The first and second resin films 3 and 4 can be bonded to the polarizer 2 through an adhesive layer or an adhesive layer (not shown). Further, the polarizing plates 10a and 10b may include other films or layers other than the first and second resin films 3 and 4.

The polarizer 2 is a film having a property of absorbing a linear polarized light having a vibrating surface parallel to its absorption axis, and a linear polarized light having a vibrating surface orthogonal to the absorption axis (parallel to the transmission axis); For example, a film obtained by adsorbing a dichroic dye to a polyvinyl alcohol resin film can be used. Examples of the dichroic dye include iodine and a dichroic organic dye.

Polyvinyl acetate The ester resin is obtained by saponification. Examples of the polyvinyl acetate-based resin include polyvinyl acetate which is a homopolymer of vinyl acetate, and a monomer which can be copolymerized with vinyl acetate (for example, an unsaturated carboxylic acid, an olefin, a vinyl ether, or not). A copolymer of saturated sulfonic acid, (meth)acrylamide having an ammonium group, and the like, and a copolymer of vinyl acetate.

The degree of saponification of the polyvinyl alcohol-based resin is usually from 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and may be, for example, a polyethylene formaldehyde or a polyvinyl acetal modified with an aldehyde. The polyvinyl alcohol-based resin generally has an average degree of polymerization of from 1,000 to 10,000, preferably from 1,500 to 5,000. Further, the average degree of polymerization of the polyvinyl alcohol-based resin can be determined in accordance with JIS K 6726.

Usually, a film made of a polyvinyl alcohol-based resin is used as a precursor film of the polarizer 2. The polyvinyl alcohol-based resin can be formed into a film by a known method. The thickness of the germ film is usually from 1 to 150 μm, and is preferably 10 μm or more in consideration of easiness of stretching or the like.

The polarizer 2 is, for example, a step of performing uniaxial stretching on the embryonic film, a step of dyeing the film by using a dichroic dye to adsorb the dichroic dye, a step of treating the film with an aqueous solution of boric acid, and washing the film with water. The steps are finally dried and manufactured. The thickness of the polarizer 2 is usually from 1 to 30 μm, and is preferably 20 μm or less, more preferably 15 μm or less, and particularly preferably 10 μm or less from the viewpoint of thinning of the optical film 1 to which the adhesive layer is attached.

The polarizer 2 obtained by adsorbing a dichroic dye to a polyvinyl alcohol resin film can be obtained by the following methods: 1) use a film in which a single film of a polyvinyl alcohol resin film is used as a germ film, a uniaxial stretching process and a dyeing process of a dichroic dye are applied to the film; and 2) a coating liquid (aqueous solution or the like) containing a polyvinyl alcohol resin is used. After coating the base film and drying it to obtain a base film having a polyvinyl alcohol-based resin layer, it is uniaxially stretched together with the base film, and two colors are applied to the stretched polyvinyl alcohol-based resin layer. The dyeing treatment of the pigment is followed by the method of peeling off the base film. As the base film, a film composed of a thermoplastic resin similar to the thermoplastic resin capable of constituting the first and second resin films 3 and 4 to be described later can be used, and polyethylene terephthalate or the like is preferable. A film composed of a polyester resin, a polycarbonate resin, a cellulose resin such as cellulose triacetate, a cyclic polyolefin resin such as a decene-based resin, or a polystyrene resin. According to the method of the above 2), it is easy to produce the polarizer 2 of the film. For example, it is easy to produce the polarizer 2 having a thickness of 7 μm or less.

The first and second resin films 3 and 4 may be thermoplastic resins each having a light transmissive property, and are preferably optically transparent thermoplastic resins such as a chain polyolefin resin (polyethylene resin, poly a polyolefin resin such as a propylene resin or a cyclic polyolefin resin (such as a decene-based resin); a cellulose resin (such as a cellulose ester resin); and a polyester resin (polyethylene terephthalate). Ethylene glycol, polyethylene naphthalate, polybutylene terephthalate, etc.; polycarbonate resin (for example, 2,2-bis(4-hydroxyphenyl)propane and the like derived from bisphenol (carbonate or the like); (meth)acrylic resin; polystyrene resin; polyether ether ketone resin; polyfluorene resin, or a film composed of such a mixture or a copolymer. Among these, the first and second trees It is preferable that each of the fat films 3 and 4 is a film composed of a cyclic polyolefin resin, a polycarbonate resin, a cellulose resin, a polyester resin, and a (meth)acrylic resin. A film composed of a cellulose resin and a cyclic polyolefin resin is particularly preferable.

Examples of the chain-like polyolefin resin include a homopolymer of a chain olefin such as a polyethylene resin or a polypropylene resin, and a copolymer composed of two or more kinds of chain olefins.

The cyclic polyolefin-based resin is a general term for a resin containing a cyclic olefin represented by norbornene, tetracyclododecene (alias: dimethicone) or such a derivative as a polymerization unit. Examples of the cyclic polyolefin-based resin include a ring-opened (co)polymer of a cyclic olefin, a hydrogenated product thereof, an addition polymer of a cyclic olefin, a cyclic olefin, and a chain olefin such as ethylene or propylene or ethylene. A copolymer of an aromatic compound and a modified (co)polymer modified with the unsaturated carboxylic acid or a derivative thereof. Among these, a norbornene-based resin which uses a norbornene-based monomer such as a norbornene or a polycyclic norbornene-based monomer as a cyclic olefin is preferred.

The cellulose resin is preferably a cellulose ester resin, that is, a partial or complete esterified product of cellulose, and examples thereof include cellulose acetate, propionate, butyrate, and mixed esters thereof. . Among these, cellulose triacetate, cellulose diacetate, cellulose acetate propionate, cellulose acetate butyrate, and the like are preferred.

The polyester-based resin is a resin other than the cellulose ester-based resin having an ester bond, and is usually composed of a polycondensate of a polyvalent carboxylic acid or a derivative thereof and a polyhydric alcohol. As the polyester resin, for example, a poly pair Ethylene phthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, propylene naphthalate, poly Dimethyl chlorophthalate, cyclohexane dimethyl phthalate, and the like.

The polycarbonate resin is a polyester formed of carbonic acid, a diol or a bisphenol. Among these, from the viewpoint of heat resistance, weather resistance, and acid resistance, an aromatic polycarbonate having a diphenyl alkane in a molecular chain is preferred. Examples of the polycarbonate include 2,2-bis(4-hydroxyphenyl)propane (alias bisphenol A), 2,2-bis(4-hydroxyphenyl)butane, and 1,1-double. Polycarbonate derived from bisphenols such as (4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)isobutane, 1,1-bis(4-hydroxyphenyl)ethane Ester and the like.

The (meth)acrylic resin which can constitute the first and second resin films 3 and 4 can be a polymer having a structural unit derived from methacrylate as a main component (for example, containing 50% by weight or more), and Copolymers obtained by copolymerization with other copolymerization components are preferred.

The (meth)acrylic resin may contain two or more kinds of structural units derived from methacrylate. Examples of the methacrylate include C ₁ to C ₄ alkyl methacrylates such as methyl methacrylate, ethyl methacrylate and butyl methacrylate.

An acrylate is mentioned as a copolymerization component which can copolymerize with a methacrylate. The acrylate is preferably a C ₁ to C ₈ alkyl ester of acrylic acid such as methyl acrylate, ethyl acrylate, butyl acrylate or 2-ethylhexyl acrylate. Specific examples of the other copolymerization component include unsaturated acids such as (meth)acrylic acid; aromatic vinyl compounds such as styrene, halogenated styrene, α-methylstyrene, and vinyltoluene; Vinyl cyanide compound such as acrylonitrile; unsaturated acid anhydride such as maleic anhydride or citraconic anhydride; unsaturated hydrazine such as phenyl maleimide or cyclohexylmethyleneimine A compound other than an acrylate having one polymerizable carbon-carbon double bond in the molecule such as an imine. A compound having two or more polymerizable carbon-carbon double bonds in the molecule may be used as a copolymerization component. The copolymerization component can be used singly or in combination of two or more.

The (meth)acrylic resin may have a ring structure in the polymer main chain in order to improve the durability of the film. The ring structure is preferably a heterocyclic structure such as a cyclic acid anhydride structure, a cyclic quinone imine structure or a lactone ring structure. Specific examples of the cyclic acid anhydride structure include a glutaric anhydride structure and a succinic anhydride structure. Specific examples of the cyclic quinone imine structure include a Glutarimide structure and amber imine. Specific examples of the lactone ring structure, such as a structure, and the like, include a butyrolactone ring structure and a valerolactone ring structure.

The (meth)acrylic resin may contain acrylic rubber particles from the viewpoint of film forming properties of the film, impact resistance of the film, and the like. The acrylic rubber particles are particles in which an elastic polymer mainly composed of acrylate is used as an essential component, and a single-layer structure consisting essentially of the elastic polymer or an elastic polymer is set as 1 The multilayer structure of the layer. Examples of the elastic polymer include a crosslinked elastic copolymer obtained by copolymerizing an alkyl acrylate as a main component with another vinyl monomer and a crosslinkable monomer copolymerizable. The alkyl acrylate which is a main component of the elastic polymer may, for example, be a C ₁ to C ₈ alkyl ester of acrylic acid such as methyl acrylate, ethyl acrylate, butyl acrylate or 2-ethylhexyl acrylate. The carbon number of the alkyl group is preferably 4 or more.

Examples of the other vinyl monomer copolymerizable with the alkyl acrylate include a compound having one polymerizable carbon-carbon double bond in the molecule, and more specifically, a methyl group such as methyl methacrylate. An acrylate, an aromatic vinyl compound such as styrene, a vinyl cyanide compound such as (meth)acrylonitrile, or the like. The crosslinkable monomer may be a crosslinkable compound having at least two polymerizable carbon-carbon double bonds in the molecule, and more specifically, ethylene glycol di(meth)acrylate or dibutyl An (meth) acrylate of a polyhydric alcohol such as an alcohol di(meth)acrylate, an enester of (meth)acrylic acid such as allyl (meth)acrylate, and divinylbenzene.

The content of the acrylic rubber particles is preferably 5 parts by weight or more, and preferably 10 parts by weight or more based on 100 parts by weight of the (meth)acrylic resin. When the content of the acrylic rubber particles is too large, the surface hardness of the film is lowered, and when the film is subjected to surface treatment, the solvent resistance to the organic solvent in the surface treatment agent is lowered. Therefore, the content of the 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 can contain usual additives in the technical field of the present invention. Examples of the additive include an ultraviolet absorber, an infrared absorber, an organic dye, a pigment, an inorganic dye, an antioxidant, an antistatic agent, a surfactant, a lubricant, a dispersant, and a heat stabilizer. Examples of the ultraviolet absorber include a salicylate compound, a diphenylketone compound, a benzotriazole compound, and three A compound, a cyano (meth) acrylate compound, a nickel salt or the like.

Each of the first and second resin films 3 and 4 may be either an unstretched film or a film that is uniaxially or biaxially stretched. The first resin film 3 and/or the second resin film 4 may be a protective film serving as the protective polarizer 2, or may be a protective film having an optical function as a retardation film to be described later. Further, the first resin film 3 and the second resin film 4 may be the same or different films.

Further, the first resin film 3 and/or the second resin film 4 may have a hard coat layer, an antiglare layer, an antireflection layer, a light diffusion layer, and an anti-reflection layer on the outer surface (the surface opposite to the polarizer 2). A surface treatment layer (coating layer) of an electrostatic layer, an antifouling layer, a conductive layer, or the like. The thickness of each of the first resin film 3 and the second resin film 4 is usually 1 to 150 μm, preferably 5 to 100 μm (for example, 5 to 60 μm), more preferably 50 μm or less (for example, 1 to 40 μm), and still more preferably Below 30 μm (for example, 5 to 25 μm).

In particular, in the case of a small-sized polarizing plate such as a smart phone or a flat-type terminal device, it is preferable to use a thinner one having a thickness of 30 μm or less as the first resin film 3 and/or the second. The resin film 4 is weak in the strength of the polarizing plate 2 and suppresses the contraction force of the polarizer 2, and the durability is likely to be insufficient. When such a polarizing plate is used as the optical film 10, the optical film 1 with an adhesive layer of the present invention also has good durability.

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

As a water-based adhesive, a conventional water system can be cited. An agent (for example, an adhesive composed of a polyvinyl alcohol-based resin aqueous solution, an aqueous two-liquid urethane emulsion adhesive, an aldehyde compound, an epoxy compound, a melamine compound, a methylol compound, an isocyanate compound, or an amine) a crosslinking agent such as a compound or a polyvalent metal salt or the like). Among these, a water-based adhesive composed of a polyvinyl alcohol-based resin aqueous solution can be suitably used. In the case of using a water-based adhesive, it is preferable to apply a drying step for removing water contained in the aqueous adhesive after bonding the polarizer 2 to the first and second resin films 3 and 4. After the drying step, a ripening step of curing at a temperature of, for example, about 20 to 45 ° C may be provided.

The above-mentioned active energy ray-curable adhesive agent is an adhesive which is cured by irradiation with an active energy ray such as an ultraviolet ray or an electron beam, and examples thereof include a curable composition containing a polymerizable compound and a photopolymerization initiator, and The curable composition of the photoreactive resin, the curable composition containing the binder resin and the photoreactive crosslinking agent, and the like are preferably an ultraviolet curable adhesive.

When the active energy ray-curable adhesive is used, the curing step is performed by bonding the polarizer 2 to the first and second resin films 3 and 4, and then performing a drying step as needed, and then irradiating the active energy ray. The active energy ray-curable adhesive is cured. The light source of the active energy ray is not particularly limited, and it is preferably an ultraviolet ray having a light-emitting distribution at a wavelength of 400 nm or less.

As a method of bonding the polarizer 2 to the first and second resin films 3 and 4, a surface to which one of the bonding surfaces is subjected to saponification treatment, corona treatment, plasma treatment, or the like can be given. Method of activation treatment Wait. When the resin film is bonded to both surfaces of the polarizing film 2, the adhesive for bonding the resin films may be the same kind of adhesive or a different type of adhesive.

The polarizing plates 10a and 10b can further contain other films or layers. Specific examples thereof include a retardation film to be described later, and a brightness enhancement film, an antiglare film, an antireflection film, a diffusion film, a light concentrating film, an adhesive layer other than the adhesive layer 20, a coating layer, a protective film, and the like. The protective film is used for the purpose of protecting the surface of the optical film 10 such as a polarizing plate from scratches and contamination, and is usually after the optical film 1 with the adhesive layer is attached to, for example, a metal layer or a substrate. Stripped and removed.

The protective film is usually composed of a base film and an adhesive layer laminated thereon. The base film may be a thermoplastic resin, for example, a polyolefin resin such as a polyethylene resin or a polypropylene resin; a polyester resin such as polyethylene terephthalate or polyethylene naphthalate; A polycarbonate resin or a (meth)acrylic resin is used.

[2-3] phase difference plate

The retardation film contained in the retardation film is an optical film exhibiting optical anisotropy as described above, and may be a stretched film obtained by stretching a resin film to about 1.01 to 6 times, which is obtained by a resin film. In the above, the thermoplastic resin which can be used in the first and second resin films 3 and 4, and, for example, a polyvinyl alcohol resin, a polyarylate resin, a polyimide resin, a polyether oxime resin, A polyvinylidene fluoride/polymethyl methacrylate resin, a liquid crystal polyester resin, an ethylene-vinyl acetate copolymer saponified product, a polyvinyl chloride resin, or the like. Such Among them, a stretched film obtained by uniaxially stretching or biaxially stretching a polycarbonate resin film, a cyclic olefin resin film, a (meth)acrylic resin film or a cellulose resin film is preferred. Further, in the present specification, a film having a zero hysteresis value is also included in the retardation film (however, it can also be used as a protective film). Further, a film called a uniaxial retardation film, a wide viewing angle retardation film, or a low photoelastic modulus retardation film can also be applied as a retardation film.

The zero hysteresis value film refers to a film in which the in-plane phase difference value R _e and the thickness direction phase difference value R _{th are} both -15 to 15 nm. This retardation film can be suitably used in a liquid crystal display device of the IPS mode. The in-plane phase difference value R _e and the thickness direction phase difference value R _th are preferably -10 to 10 nm at the same time, more preferably -5 to 5 nm at the same time. The in-plane phase difference value R _e and the thickness direction phase difference value R _th are referred to as values at a wavelength of 590 nm.

The in-plane phase difference value R _e and the thickness direction phase difference value R _th are each defined by the following formula:

R _e =(n _x -n _y )×d

R _th =[(n _x +n _y )/2-n _z ]×d

Wherein, _n-x is a slow axis direction (x axis direction) of the refractive index in the film plane, _n-y is the refractive index of fast axis direction (x-axis and y-axis direction orthogonal to the in-plane) in the plane of the film, n _z is a refractive index in the film thickness direction (z-axis direction perpendicular to the film surface), and d is a film thickness.

In the film having a zero hysteresis value, for example, a polyolefin resin such as a cellulose resin, a chain polyolefin resin, or a cyclic polyolefin resin, or a polyethylene terephthalate resin or (meth) can be used. Acrylic A resin film composed of a resin. In particular, since the phase difference value is easily controlled and easily obtained, a cellulose resin, a polyolefin resin, or a (meth)acrylic resin can be suitably used.

In addition, a film which exhibits optical anisotropy due to application and alignment of a liquid crystal compound, and a film which exhibits optical anisotropy due to application of an inorganic layered compound can be used as a retardation film. Such a retardation film is a film which is called a temperature-compensated retardation film, and a JX Nippon Nippon ENERGY Co., Ltd., which is sold under the trade name of "NH FILM", has a film of a rod-like liquid crystal. Fuji FILM (shares) sold under the trade name "WV FILM", a film with a disc-shaped liquid crystal, and a full biaxial alignment film sold under the trade name "VAC FILM" by Sumitomo Chemical Co., Ltd. A biaxially oriented film sold by Sumitomo Chemical Co., Ltd. under the trade name "new VAC FILM". Further, the resin film laminated on at least one surface of the retardation film can be, for example, the above-mentioned protective film.

[3] Optical laminate

4 to 8 are schematic cross-sectional views showing an example of an optical layered body including an optical film having an adhesive layer formed of the adhesive composition of the present invention.

The optical layered body 5 shown in Fig. 4 is obtained by laminating a metal layer 30 (or a metal wiring layer 30) laminated on a substrate 40 on the optical film 1a of the above-mentioned adhesive layer (or polarization of an adhesive layer). An optical layered body formed on the side of the adhesive layer side of the board 1a). The optical film 1a with the adhesive layer is formed by laminating the adhesive layer 20 on the side of the polarizing plate 2 of the polarizing plate 10a.

Figure 5 shows the optical laminate 6, which will have been laminated The metal layer 30 on the substrate 40 is laminated on the surface of the adhesive film layer of the optical film 1b (or the polarizing plate 1b to which the adhesive layer is attached) of the adhesive layer. The optical film 1b with the pressure-sensitive adhesive layer is an optical film in which an adhesive layer 20 is laminated on the surface of the second resin film 4 of the polarizing plate 10b.

The optical laminates 5 and 6 can be obtained by laminating the optical film (1a, 1b) with the adhesive layer through the adhesive layer 20, wherein the metal layer 30 is laminated on the substrate 40. .

As a method of forming the metal layer 30 on the substrate 40, for example, a sputtering method or the like can be given. 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 of the glass substrate, soda lime glass, low alkali glass, alkali-free glass, or the like can be used. The metal layer 30 may be formed on the entire surface of the substrate 40 or may be formed in a part thereof.

The metal layer 30 may be, for example, a layer containing at least one metal element selected from the group consisting of aluminum, copper, silver, iron, tin, zinc, nickel, molybdenum, chromium, tungsten, lead, and an alloy containing the two or more metals. Among these, from the viewpoint of conductivity, it is preferably a layer containing at least one metal element selected from the group consisting of aluminum, copper, silver, and gold, and from the viewpoint of conductivity and cost, it is preferably It may be a layer containing an aluminum element, and more preferably a layer containing an aluminum element as a main component (according to 50% by weight or more of the total metal component 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 both the metal layer 30 and ITO or the like. A transparent electrode layer composed of a metal oxide. Further, a metal mesh in which a thin metal wire layer is disposed on a substrate, or a layer in which a metal nanoparticle or a metal nanowire is added to a binder may be used.

The method of preparing the metal layer 30 is not particularly limited, and may be a metal foil, or may be formed by a vacuum deposition method, a sputtering method, an ion plating method, an inkjet printing method, or a gravure printing method. A metal layer formed by a sputtering method, an inkjet printing method, or a gravure printing method is preferred, and a metal layer formed by sputtering is more preferable. 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. Further, 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.

The optical layered body 7 shown in Fig. 6 is an optical layered body in which the adhesive layer 20 of the optical film 1 with the adhesive layer is laminated on the substrate 40.

The optical layered body 8 shown in Fig. 7 is a resin layer 50 which is further laminated on the surface of the metal layer 30 which has been laminated on the substrate 40 (on the surface opposite to the substrate 40), and laminated in the foregoing. An optical layered body in which the surface of the optical film 1 of the adhesive layer is adhered to the side of the adhesive layer 20. The resin constituting the resin layer 50 may, for example, be a resin constituting the first or second resin film exemplified above.

The optical layered body 9 shown in Fig. 8 is formed by laminating a plurality of metal layers 30 on the substrate 40 at a predetermined interval in the longitudinal and lateral directions. And the resin layer 50 is formed (or laminated) on the surface (or gap) of the plurality of metal layers 30 and on the surface of the metal layer 30 (on the surface opposite to the substrate 40), and the optical layered body 7 is the same. same. In the form of the optical layered body 8 (the pattern in which the metal layer 30 is patterned into a predetermined shape), the metal layer 30 may be, for example, a metal wiring layer of a touch input element of a touch input type liquid crystal display device ( That is, the electrode layer).

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

When the optical film (1, 1a, 1b) with the adhesive layer is bonded to the substrate 40 (glass substrate, transparent substrate, etc.) or the metal layer 30 (transparent electrode layer) to produce an optical layered body, if some defects occur. In some cases, it is necessary to peel the optical film with the adhesive layer from the substrate 40 or the metal layer 30, and reattach the other optical film 1 with the adhesive layer to the substrate 40 or the metal layer 30, that is, so-called rework operation. . The optical film 1 to which the adhesive layer formed of the adhesive composition of the present invention is attached is less likely to cause clouding, residual glue, or the like on the surface of the glass substrate or the transparent electrode after peeling, and has excellent reworkability.

[4] Liquid crystal display device

The liquid crystal display device of the present invention comprises the optical film 1 having the above-described adhesive layer formed of the adhesive composition of the present invention, and more typically comprises the above optical laminate.

Therefore, the liquid crystal display device of the present invention has excellent durability.

The liquid crystal display device of the present invention may also be a touch input liquid crystal display device having a touch panel function. The touch input type liquid crystal display device includes a touch input element including a liquid crystal cell, and a backlight. The structure of the touch panel can be a well-known type (for example, an out-cell type, an in-cell type, an in-cell type, etc.), and a touch panel operation mode can be known. The method [for example, a resistive film method, a capacitance method (surface type electrostatic capacitance method, projection type electrostatic capacitance method), etc.]. The optical film 1 with the adhesive layer of the present invention can be disposed on the identification side of the touch input element (liquid crystal cell), or can be disposed on the backlight side, or can be disposed on both sides. The driving method of the liquid crystal cell may be any of the previously known methods such as the TN mode, the VA mode, the IPS mode, the multi-domain mode, and the OCB mode. Further, in the liquid crystal display device of the present invention, the substrate 40 included in the optical layered body may be a substrate (typically a glass substrate) included in the liquid crystal cell.

[Examples]

Hereinafter, the present invention will be more specifically described by way of examples and comparative examples, but the present invention is not limited by the examples. Unless otherwise stated, the amounts used, the parts by weight, and the % are all based on the weight.

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

In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, and a stirrer, a solution obtained by mixing 81.8 parts of ethyl acetate with a monomer having a composition shown in Table 1 (the numerical value of Table 1 is a part by weight) was added. After replacing the air in the reaction vessel with nitrogen, the internal temperature was made 60 °C. Subsequently, adding azo double 0.12 part of isobutyronitrile was dissolved in 10 parts of ethyl acetate. After maintaining at the same temperature for 1 hour, ethyl acetate was continuously added to the reaction vessel at an addition rate of 17.3 parts/Hr while maintaining the internal temperature at 54 to 56 ° C so that the concentration of the polymer became about 35%. From the start of the addition of ethyl acetate to the lapse of 12 hours, the internal temperature was maintained at 54 to 56 ° C, and then ethyl acetate was further added to adjust the concentration of the polymer to 20% to obtain a (meth)acrylic resin (A). -1) Ethyl acetate solution. The weight average molecular weight Mw of the obtained (meth)acrylic resin (A-1) was 1.39 million, and the ratio (Mw/Mn) of the weight average molecular weight Mw and the number average molecular weight Mn was 5.32.

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

The ethyl acetate solution of the (meth)acrylic resin (A-2 to 12) was obtained in the same manner as in Production Example 1 except that the composition of the monomer was changed to the composition shown in Table 1 (resin concentration: 20%). . The weight average molecular weight Mw of the obtained (meth)acrylic resin (A-2 to 12) is in the range of 1.3 million to 1,500,000, and Mw/Mn is in the range of 4 to 6.

In the above-mentioned production example, the weight average molecular weight Mw and the number average molecular weight Mn are "TSKgel XL" made of 4 TOSOH (shares) and "Shodex GPC KF-802" made by 1 Showa Denko (share). A total of five tubes were used as a column, and they were placed in a GPC apparatus in series, and tetrahydrofuran was used as an eluent. The sample concentration was 5 mg/mL, the sample introduction amount was 100 μL, the temperature was 40 ° C, and the flow rate was 1 mL/min. It is measured by standard polystyrene conversion. Get GPC The conditions for discharging the curve are also the same.

Glass transition temperature Tg is based on SII Nano A differential scanning calorimeter (DSC) "EXSTAR DSC6000" manufactured by Technology Co., Ltd. was measured under a nitrogen atmosphere at a measurement temperature range of -80 to 50 ° C and a temperature increase rate of 10 ° C / min.

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

The abbreviations in the "monomer composition" column of Table 1 mean the following monomers.

BA: butyl acrylate (glass transition temperature of the homopolymer: -54 ° C), MA: methyl acrylate (glass transition temperature of the homopolymer: 10 ° C), HEA: 2-hydroxyethyl acrylate.

4HBA: 4-hydroxybutyl acrylate

5HPA: 5-hydroxypentyl acrylate

PEA: phenoxyethyl acrylate

PEA2: phenoxy diethylene glycol acrylate

BMAA: Butoxymethyl propylene amide

AA: Acrylic

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

(1) Modulation of adhesive composition

In the ethyl acetate solution (resin concentration: 20%) of the (meth)acrylic resin obtained in the above production example, 100 parts of the solid matter with respect to the solution was the amount (parts by weight) shown in Table 2 The crosslinking agent (B), the decane compound (C), and the ionic compound (D) were mixed, and ethyl acetate was added so that the solid content concentration became 14%, and the adhesive composition was obtained. The blending amount of each of the blending components shown in Table 2 is a part by weight of the active ingredient contained in the product to be used when a solvent or the like is used.

The details of each of the blending components indicated by the abbreviation in Table 2 are as follows.

(crosslinking agent)

B-1: Ethyl acetate solution of a trimethylolpropane adduct of toluene diisocyanate (solid content: 75%), and the trade name "CORONATE L" obtained from TOSOH (share).

B-2: Ethyl acetate solution of trimethylolpropane adduct of xylene diisocyanate (solid content: 75%), trade name "TAKENATE D-110N" obtained from Mitsui Chemicals Co., Ltd.

(decane compound)

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

(ionic compound)

D-1: bis(fluorosulfonyl)imine N-decylpyridinium, D-2: potassium bis(fluorosulfonyl)imide, D-3: bis(trifluoromethylsulfonyl) Lithium amine, D-4: N-decylpyridinium tetrakis(pentafluorophenyl)borate.

(2) Manufacture of adhesive layer

Each of the adhesive compositions prepared in the above (1) was applied to a polyethylene terephthalate film which had been subjected to release treatment by using an applicator so as to have a thickness after drying of 20 μm. The release film (trade name "PLR-382051" obtained from LINTEC Co., Ltd.) was subjected to a release treatment surface, and dried at 100 ° C for 1 minute to prepare an adhesive layer (adhesive sheet).

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

A polyvinyl alcohol film (Kuraray Vinylon VF-PE #6000, manufactured by Kuraray Co., Ltd.) having an average polymerization degree of about 2,400, a saponification degree of 99.9 mol%, and a thickness of 60 μm was immersed in pure water at 37 ° C. It was immersed in an aqueous solution containing iodine and potassium iodide (iodine/potassium iodide/water (weight ratio) = 0.04/1.5/100) at 30 °C. Subsequently, 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. The film was washed with pure water at 10 ° C, and then dried at 85 ° C to obtain a polarizer having a thickness of about 23 μm in the form of iodine adsorbed on the polyvinyl alcohol. The extension 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 [Konica Minolta (trade name "KC2UA") made of a cellulose triacetate film having a thickness of 25 μm is passed through an adhesive composed of an aqueous solution of a polyvinyl alcohol resin. One side of the obtained polarizer. Then, a zero-phase retardation film (trade name "ZEONOR" manufactured by Nippon Zeon Co., Ltd.) made of a cyclic polyolefin resin having a thickness of 23 μm is passed through an adhesive composed of an aqueous solution of a polyvinyl alcohol resin. A polarizing plate was produced by laminating the surface of the polarizer opposite to the cellulose triacetate film. Next, after the corona discharge treatment for improving the adhesion is performed on the surface of the zero retardation film which is in contact with the polarizer, the adhesive made in the above (2) is bonded by the bonding machine. The coating layer was bonded to the surface (adhesive layer) on the opposite side of the separation membrane, and then aged at a temperature of 23 ° C and a relative humidity of 65% for 7 days to obtain an optical film (P-1) with an adhesive layer.

(4) Durability evaluation of optical film with adhesive layer

The optical film (P-1) with the adhesive layer prepared in the above (3) is cut to a size of 300 mm × 220 mm so that the direction of the axis of extension of the polarizing plate is long, and the separation film is peeled off to be exposed. The adhesive layer is applied to a glass substrate or a glass substrate with ITO (tin-doped indium oxide). The obtained test piece to which the glass substrate was attached (an optical film to which an adhesive layer of a glass substrate was attached) was pressurized in an autoclave at a temperature of 50 ° C and a pressure of 5 kg/cm ² (490.3 kPa) for 20 minutes. . As the glass substrate, an alkali-free glass product name "Eagle XG" manufactured by Corning Co., Ltd. was used. In addition, as a glass substrate with ITO, an ITO layer of 30 nm was formed by an ITO layer to be formed into an alkali-free glass (trade name "Eagle XG") manufactured by Corning.

Three kinds of durability tests described below were carried out on the obtained optical laminate.

[Endurance test]

耐热 Maintain heat resistance test (glass substrate) for 1000 hours under dry conditions at 95 ° C. 耐热 Maintain heat resistance test (glass with ITO) for 1000 hours under dry conditions at 95 ° C. 耐 Maintaining a heat and humidity test (glass substrate) for 1000 hours at a temperature of 60 ° C and a relative humidity of 90%, ̇ will be kept at a temperature of 85 ° C for 30 minutes under drying conditions, and then kept at a temperature of -40 ° C for 30 minutes to be set to 1 cycle, and it is repeated for 1000 cycles of thermal shock (HS) test (glass substrate) .

The optical laminate after each test was visually observed, and the appearance change of the adhesive layer such as floating, peeling, foaming, etc. was visually observed. The durability was evaluated according to the following evaluation criteria. The results are shown in Table 3.

5: No change in appearance such as floating, peeling, foaming, etc. was observed at all, 4: almost no change in appearance such as floating, peeling, foaming, etc., and 3: appearance change such as floating, peeling, foaming, etc. Obviously, 2: the appearance of floating, peeling, foaming, etc. changes significantly, and 1: the appearance change of floating, peeling, foaming, etc. can be clearly observed.

(5) Adhesion evaluation of optical film with adhesive layer

The optical film (P-1) with the adhesive layer prepared in the above (3) was cut into a test piece having a size of 25 mm × 150 mm. The separator was peeled off from the test piece, and the adhesive surface was attached to the glass substrate. The obtained test piece to which a glass substrate was attached (an optical film to which an adhesive layer of a glass substrate was attached) was pressurized in an autoclave at a temperature of 50 ° C and a pressure of 5 kg/cm ² (490.3 kPa). minute. After storing in an environment of a temperature of 23 ° C and a relative humidity of 50% for 24 hours, the optical film and the adhesive layer were simultaneously peeled from the test piece to the 180° direction at a speed of 300 mm/min. The average peeling force at the time of peeling was set as the adhesive force and it is shown in Table 3. When the adhesive force is 10 N or less, it has excellent reworkability, and when it is 0.5 N or more, peeling is unlikely to occur even when it is subjected to punching from the end portion of the polarizing plate.

[Evaluation of ITO Corrosion of Optical Laminates]

The surface resistance (surface resistance value before the test) of the surface of the ITO layer of the glass substrate with an ITO layer was measured using a low resistivity meter [trade name "Loresta AX" manufactured by Mitsubishi Chemical Analytech Co., Ltd.]. Next, the polarizing plate formed with the adhesive layer prepared in the above (3) is cut into a size of 20 mm × 40 mm. The sheet was attached to the ITO layer side of the glass substrate through an adhesive layer. The obtained optical layered body was stored in an oven at a temperature of 60 ° C and a relative humidity of 90% for 500 hours, and then peeled off between the ITO layer and the pressure-sensitive adhesive layer in an environment of a temperature of 23 ° C and a relative humidity of 50%. The surface resistance (surface resistance value after the test) of the ITO layer after peeling was measured. The rate of change in resistance before and after the test was calculated according to the following formula and evaluated based on the following criteria. The smaller the rate of change in resistance, the lower the corrosion 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 corrosion properties>

○: An optical layered body having a resistance change rate of less than 50% and having excellent ITO corrosion resistance.

X: The rate of change in electric resistance was 50% or more, and the ITO corrosion resistance of the optical layered product was poor.

(6) Evaluation of antistatic property of optical film with adhesive layer

After peeling off the separator of the obtained polarizing film of the adhesive layer, the surface resistance of the adhesive was measured using a surface specific resistance measuring device [Hiresta-up MCP-HT450 (trade name) manufactured by Mitsubishi Chemical Corporation). value. It was carried out under the measurement conditions of applying a voltage of 250 V and an application time of 10 seconds. When the surface resistance value 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 adhesive sheet of the present invention is disclosed. The greater the gel fraction, the more crosslinking reaction will take place in the adhesive and can be set as the target for crosslink density. The gel fraction is determined according to the following (1) to (4). The value.

(1) An adhesive sheet having an area of about 8 cm × about 8 cm is bonded to a metal mesh of SUS304 of about 10 cm × 10 cm (the weight is made Wm).

(2) The laminate obtained in the above (1) was weighed and set to have a weight of Ws, and secondly, folded four times in a manner of encapsulating the adhesive sheet and fixed by a stapler (stapler). The amount is set to Wb.

(3) The mesh of the above (2) fixed by the stapler was placed in a glass container, and 60 mL of ethyl acetate was added thereto for immersion, and then the glass container was stored at room temperature for 3 days.

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

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

1‧‧‧Optical film with adhesive layer

10‧‧‧Optical film

20‧‧‧Adhesive layer

Claims (12)

An adhesive composition comprising a (meth)acrylic resin (A), a crosslinking agent (B), and a decane compound (C), wherein the (meth)acrylic resin (A) contains: a source a structural unit of a hydroxyl group-containing (meth) acrylate represented by 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, X ¹ represents a methylene group which may have a substituent, and when n is 2 or more, the substituents may be the same or different; a structural unit derived from a hydroxyl group-containing (meth) acrylate represented by 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, and X ² represents a methylene group which may have a substituent, and the substituents may be the same or different; and the crosslinking agent (B) is a An adduct obtained by adding a polyhydric alcohol compound to a toluene diisocyanate compound and/or a toluene diisocyanate compound. The adhesive composition according to claim 1, wherein the hydroxyl group-containing (meth) represented by the formula (a1) is 100 parts by weight based on the total structural unit constituting the (meth)acrylic resin. Acrylate structure The ratio of the unit is from 1.5 to 4.5 parts by weight, and the ratio derived from the structural unit of the hydroxyl group-containing (meth) acrylate represented by the formula (a2) is from 0.25 to 1.0 part by weight. The adhesive composition according to claim 1 or 2, wherein the (meth)acrylic resin contains a structural unit derived from an alkyl acrylate (a3) derived from an alkyl acrylate (a3). The structural unit comprises: a structural unit derived from a homopolymer of a methacrylate (a3-1) having a glass transition temperature of less than 0° C.; and an acrylic acid derived from a homopolymer having a glass transition temperature of 0° C. or more a structural unit of an alkyl ester (a3-2). The adhesive composition according to claim 3, wherein the glass transition temperature derived from the homopolymer is a structural unit of the alkyl acrylate (a3-1) which is less than 0 ° C, and is derived from the same element. The ratio (weight ratio) between the structural units of the alkyl acrylate (a3-2) having a glass transition temperature of the polymer of 0 ° C or higher is (a3-1) / (a3-2) = 20 / 80 to 95 / 5. The adhesive composition according to any one of claims 1 to 4, wherein the (meth)acrylic resin has a weight average molecular weight of 6.0 × 10 ⁵ to 2.5 × 10 ^{6 in terms of} polystyrene. The adhesive composition according to any one of claims 1 to 5, wherein the ratio of the crosslinking agent (B) is 0.01 to 100 parts by weight of the (meth)acrylic resin (A). 10 parts by weight. The adhesive composition according to any one of claims 1 to 6, wherein the decane compound (C) is a decane compound represented by the following formula (c1), In the formula, 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 aforementioned alkanediyl group and the aforementioned alicyclic hydrocarbon group may be substituted into -O - or -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 each independently represent an alkyl group having 1 to 5 carbon atoms or a carbon number of 1 Alkoxy group to 5. The adhesive composition according to claim 7, wherein B of the formula (c1) is an alkanediyl group having 1 to 10 carbon atoms, and R ¹ is an alkyl group having 1 to 5 carbon atoms, R ² and R. ³ , R ⁴ , R ⁵ and R ⁶ are each independently an alkoxy group having 1 to 5 carbon atoms. The adhesive composition according to any one of claims 1 to 8, wherein the ratio of the decane compound (C) is 0.01 to 10 with respect to 100 parts by weight of the (meth)acrylic resin (A). Parts by weight. The adhesive composition according to any one of claims 1 to 9, wherein the adhesive formed from the adhesive composition has a gel fraction of 50 to 95%. The adhesive composition according to any one of claims 1 to 10, wherein the adhesive layer formed of the adhesive composition is bonded to a glass substrate at a temperature of 23 ° C and a relative humidity of 50%. The adhesion of the aforementioned adhesive layer after 24 hours was 0.5 to 10 N/25 mm at a peeling speed of 300 mm/min. The adhesive composition according to any one of claims 1 to 11, which is used for forming an adhesive layer laminated on an optical film.