TW201432001A - Adhesive composition, adhesive and adhesive sheet - Google Patents

Abstract

This invention provides an adhesive composition, an adhesive and an adhesive sheet with the excellent durability and sealing property for optical components such as polarizers. To address the aforesaid subject, as disclosed is an adhesive composition having a weight average molecular weight of 0.8 million to 3 million and comprising: as the monomer unit of the polymer, the (meth) acrylate ester polymer having monomers containing alicyclic structures (A); the crosslinker (B); and the silane coupler (C), which has a mercapto group as the functional group to react with the organic material.

Description

Adhesive composition, adhesive and adhesive sheet

The present invention relates to an adhesive composition, an adhesive (a material for bridging an adhesive composition), and an adhesive sheet, and more particularly to an adhesive composition suitable for use as an optical member such as a polarizing plate. Adhesive and adhesive sheet.

In recent years, in various electronic devices, a touch panel having both a display device and an input means has been frequently used. The types of touch panels are mainly resistive, capacitive, optical, and ultrasonic. The resistive touch panel has analog data resistance and mother resistance. The capacitive touch panel has a surface type and a projection type.

The touch panel of mobile electronic devices such as smart phones and tablet terminals that have recently attracted attention has mostly used projection type capacitive touch panels. As a projection type capacitive touch panel of the above-described mobile electronic device, for example, it has been proposed to laminate a liquid crystal display device (LCD), an adhesive layer, a transparent conductive film (indium tin oxide: ITO), and glass in order from bottom to top. A touch panel of a protective layer such as a substrate, a transparent conductive film (ITO), or a tempered glass.

As the optical member constituting the liquid crystal display device described above, a liquid crystal module is generally used. In the liquid crystal module, the alignment layer of the two transparent electrode substrates forming the alignment layer is generally disposed inside, and is disposed so as to form a predetermined interval by the spacer, and the periphery thereof is sealed, and the liquid crystal material is sandwiched between the two transparent electrode substrates. s component. Usually, outside the two transparent electrode substrates in the liquid crystal module On the side, the polarizing plate is bonded by an adhesive.

As the adhesive to be used in the touch panel, for example, an adhesive as disclosed in Patent Document 1 is known, and the adhesive is used as a monomer unit with respect to an alkyl group having 4 to 14 carbon atoms. 100 parts by weight of the alkyl (meth) acrylate, containing from 0.2 parts by weight to 20 parts by weight of the carboxyl group-containing monomer as a copolymerization component, and (meth) propylene-based polymer, and relative to (meth) propylene 100 parts by weight of the polymer, as a bridging agent, contains 0.02 parts by weight to 2 parts by weight of a peroxide, and 0.005 parts by weight to 5 parts by weight of an epoxy-based bridging agent.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2009-242786

In the touch panel as described above, recently, a polarizing plate using a polycycloolefin has been used, and the polarizing plate has been thinned as the mobile electronic device has been thinned in recent years. However, since the material of the polycycloolefin lacks the adhesiveness with the adhesive and the shrinkage of the thin polarizing plate is high, the conventional adhesive such as Patent Document 1 has low durability, and it is time-lapse or under high temperature conditions. Under hot and humid conditions, there is a problem that floating and peeling easily occur.

The present invention has been made in view of the above circumstances, and an object of the invention is to provide an adhesive composition, an adhesive, and an adhesive sheet which are excellent in adhesion and excellent in durability when applied to an optical member such as a polarizing plate.

In order to achieve the above object, first, the present invention provides a bonding The composition is characterized in that the weight average molecular weight is from 800,000 to 3,000,000, and comprises: a (meth) acrylate polymer (A) which contains a monomer having an alicyclic structure as a monomer unit constituting the polymer. The bridging agent (B); a decane coupling agent (C) having a mercapto group as a functional group reactive with an organic material (Invention 1).

In the above invention (Invention 1), the (meth) acrylate polymer of the adhesive composition has an alicyclic structure, and the adhesive composition contains a decane coupling agent having a mercapto group. The adhesive obtained by the effect of the rise has high adhesion to an optical member such as a polarizing plate, and is excellent in durability.

In the above invention (Invention 1), the (meth) acrylate polymer (A) preferably contains 0.1% by mass to 30% by mass of the monomer having the alicyclic structure as a monomer unit constituting the polymer. Body (Invention 2).

In the above invention (Invention 1, Invention 2), the alicyclic structure preferably contains a cyclohexyl skeleton, a dicyclopentadiene skeleton, an adamantane skeleton or an isobornyl skeleton (Invention 3).

In the above invention (Invention 1 to Invention 3), the (meth) acrylate polymer (A) further preferably contains 0.1% by mass to 10% by mass of a monomer having a hydroxyl group as a monomer unit constituting the polymer. Body (Invention 4).

In the above invention (Invention 1 to Invention 4), the (meth) acrylate polymer (A) preferably contains no monomer having a carboxyl group as a monomer unit constituting the polymer (Invention 5).

In the above invention (Invention 1 to Invention 5), the bridging agent (B) is preferably an isocyanate bridging agent (Invention 6).

In the above invention (Invention 1 to Invention 6), the content of the decane coupling agent (C) in the adhesive composition is relative to the (meth) acrylate. The polymer (A) is preferably used in an amount of from 0.01 part by mass to 5 parts by mass per 100 parts by mass (Invention 7).

Secondly, the present invention provides an adhesive which is obtained by bridging the above-mentioned adhesive composition (Invention 1 to Invention 7) (Invention 8).

Thirdly, the present invention provides a bonding sheet characterized in that it is an adhesive sheet having a substrate and an adhesive layer, and the adhesive layer is composed of the above-mentioned adhesive (Invention 8) (Invention 9).

In the above invention (Invention 9), the substrate is preferably an optical member (Invention 10).

In the above invention (Invention 10), the optical member is preferably a polarizing plate (Invention 11).

Fourthly, the present invention provides a bonding sheet comprising two release sheets and an adhesive layer for holding the release sheet in contact with the release faces of the two release sheets, the adhesive layer It is composed of the above-mentioned adhesive (Invention 8) (Invention 12).

The (meth) acrylate polymer of the adhesive composition according to the present invention has an alicyclic structure, and the adhesive composition is obtained by containing a decane coupling agent having a mercapto group. The adhesive has high adhesion to an optical member such as a polarizing plate, and is excellent in durability.

1A, 1B‧‧‧bonding strips

11‧‧‧Adhesive layer

12,12a,12b‧‧‧ peeling film

13‧‧‧Substrate

Fig. 1 is a cross-sectional view showing an adhesive sheet according to a first embodiment of the present invention.

Fig. 2 is a cross-sectional view showing a bonding sheet according to a second embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described.

[adhesive composition]

The adhesive composition according to the present embodiment (hereinafter referred to as "adhesive composition P") has a weight average molecular weight of 800,000 to 3,000,000, and contains (meth)acrylic acid as a monomer unit constituting the polymer. An ester polymer (A), a bridging agent (B), and a decane coupling agent (C) having a mercapto group as a functional group reactive with an organic material, the (meth) acrylate polymer (A) having an alicyclic form Structured monomer (containing alicyclic structural monomer). In the present specification, the term "(meth)acrylate" means both acrylate and methacrylate. The same is true for other similar terms. In addition, the concept of "copolymer" is also included in "polymer".

(1) (meth) acrylate polymer (A)

The (meth) acrylate polymer (A) contains a monomer having an alicyclic structure as a monomer unit constituting the polymer. In the above-mentioned adhesive composition P, the (meth) acrylate polymer (A) contains a monomer having the above alicyclic structure, and the effect of the above-mentioned decane coupling agent (C) is increased. The acrylate polymer (A) does not contain an acid component, and the obtained adhesive has high adhesion to an optical member such as a polarizing plate, particularly to a polycycloolefin optical member and a transparent conductive film, and is durable. Excellent also. It is presumed that this is because the affinity or interaction of the alicyclic structure with the optical member and the transparent conductive film is strong, and thus the decane coupling agent (C) also functions effectively. Further, the present invention does not exclude that the (meth) acrylate polymer (A) contains an acid component.

The carbon atom ring of the alicyclic structure may be a ring of a carbon atom of a saturated structure or a ring of a carbon atom containing an unsaturated bond. Moreover, the alicyclic structure may be a monocyclic alicyclic structure or a polycyclic ring such as a bicyclic ring or a tricyclic ring. Alicyclic structure. The number of carbon atoms of the alicyclic structure is preferably 5 to 20, particularly preferably 6 to 15, and still more preferably 7 to 12.

Examples of the alicyclic structure include a cyclohexyl skeleton, a dicyclopentadiene skeleton, an adamantane skeleton, an isobornyl skeleton, a cycloalkane skeleton (cycloheptane skeleton, a cyclooctane skeleton, a cyclodecane skeleton, and a cyclic oxime). Alkane skeleton, cycloundecyl skeleton, cyclododecane skeleton, etc.), cyclic olefin skeleton (cycloheptene skeleton, cyclooctene skeleton, etc.), norbornene skeleton, norbornadiene skeleton, polycyclic skeleton (cubic An alicyclic structure such as an alkane skeleton, a pentacyclodecane skeleton or an alkane skeleton, or a spiro ring skeleton, and preferably a cyclohexyl skeleton or a dicyclopentadiene skeleton which exhibits an excellent effect of improving adhesion and durability. , an adamantane skeleton or an alicyclic structure of an isobornyl skeleton.

The monomer having an alicyclic structure is preferably a (meth) acrylate monomer containing the above skeleton, and specific examples thereof include cyclohexyl (meth) acrylate and dicyclopentanyl (meth) acrylate. And adamantyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, etc., among which, Further, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate or isobornyl (meth)acrylate is exhibited, which is more excellent in adhesion and durability. These may be used alone or in combination of two or more.

The (meth) acrylate polymer (A) preferably contains 0.1% by mass to 30% by mass of the monomer having an alicyclic structure as the monomer unit constituting the polymer, and particularly preferably contains 0.2% by mass. 25 mass %, More preferably, it is 0.5 mass % - 20 mass %. When the content of the alicyclic structure-containing monomer is less than 0.1% by mass, it is difficult to obtain the above-mentioned improved adhesion and durability. Sexual effect. When the content of the alicyclic structure-containing monomer exceeds 30% by mass, the preferred adhesiveness may not be obtained as an optical use.

The (meth) acrylate polymer (A), as a monomer unit constituting the polymer, preferably contains an alkyl group having 1 to 20 carbon atoms in addition to the above-mentioned alicyclic structure-containing monomer. The alkyl acrylate is particularly preferably contained as a main component.

The (meth) acrylate polymer (A), as a monomer unit constituting the polymer, can exhibit a preferred adhesion by an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms. Sex. Examples of the (meth)acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, and (meth)acrylic acid. Base ester, n-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth) acrylate Octyl ester, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, (methyl) ) Acrylic stearyl group and the like. Among them, from the viewpoint of further improving the adhesion, a (meth) acrylate having an alkyl group having 1 to 4 carbon atoms is preferable, and methyl (meth)acrylate and n-butyl (meth)acrylate are particularly preferable. Further, these may be used alone or in combination of two or more.

The (meth) acrylate polymer (A), as a monomer unit constituting the polymer, preferably contains from 20% by mass to 99.8% by mass of an alkyl group having 1 to 20 carbon atoms of (meth)acrylic acid alkyl group. The ester is particularly preferably contained in an amount of 60% by mass to 99.5% by mass, and more preferably 75% by mass to 99% by mass.

Further, the (meth) acrylate polymer (A) serves as a constituent of the poly The monomer unit of the compound preferably contains a monomer having a hydroxyl group (containing a hydroxyl group monomer). The reactive functional group of the hydroxyl group and the bridging agent (B), particularly the isocyanate group of the isocyanate-based bridging agent, is highly reactive, and the (meth)acrylate polymer (A) is effective due to the bridging agent (B) due to these reactions. Ground bridge. The adhesive obtained by the bridge structure is more excellent in durability.

As the hydroxyl group-containing monomer, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, (methyl) a hydroxyalkyl (meth) acrylate such as 2-hydroxybutyl acrylate, 3-hydroxybutyl (meth) acrylate or 4-hydroxybutyl (meth) acrylate, etc., wherein From the viewpoint of reactivity and copolymerizability, 2-hydroxyethyl (meth)acrylate is preferred. These may be used alone or in combination of two or more.

The (meth) acrylate polymer (A) preferably contains 0.1% by mass to 10% by mass of the hydroxy group-containing monomer as the monomer unit constituting the polymer, and particularly preferably contains 0.2% by mass to 8% by mass, further It is preferably contained in an amount of 0.3% by mass to 5% by mass. When the content of the hydroxyl group-containing monomer is in the above range, the bridging structure formed is good, and the obtained adhesive has more excellent durability. When the content of the hydroxyl group-containing monomer is less than 0.1% by mass, the bridging point is too small, and it is difficult to obtain an effect of improving durability. On the other hand, when the content of the hydroxyl group-containing monomer exceeds 10% by mass, the bridging point is excessive, and the obtained binder is not soft and the stress relaxation property may be lowered.

The (meth) acrylate polymer (A) preferably contains no carboxyl group-containing monomer (containing a carboxyl group monomer) as a monomer unit constituting the polymer. It can be suppressed by a monomer which does not substantially contain a carboxyl group having an acid component The object to be attached to the obtained adhesive is poor in acid, for example, even in the case of a transparent conductive film or a metal film, it is possible to suppress the defects caused by the acid. In particular, when the attached object is a transparent conductive film, it is possible to suppress the transparent conductive film from being corroded or the resistance value of the transparent conductive film from changing. Further, as with the decane coupling agent (C) to be described later, the polymer which is not affected by the acid also functions effectively. Further, by substantially not containing a monomer having a carboxyl group, the carboxyl group can be prevented from inhibiting the reaction between the hydroxyl group containing the hydroxyl group monomer and the bridging agent (B), particularly the isocyanate-based bridging agent.

The (meth) acrylate polymer (A) may contain other monomers as needed in addition to the above monomers. The other monomer may be a monomer having a reactive functional group other than a hydroxyl group or a carboxyl group (containing a reactive functional group monomer), or may be a non-reactive monomer.

The monomer having a reactive functional group may, for example, be a monomer having an amino group (containing an amino monomer). Examples of the amino group-containing monomer include aminoethyl (meth)acrylate and n-butylaminoethyl (meth)acrylate. These may be used alone or in combination of two or more.

Examples of the non-reactive monomer include methoxymethyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, and (meth)acrylic acid. (meth) acrylate, acrylamide, methacrylamide containing an aromatic ring such as an alkoxyalkyl (meth) acrylate or a (meth) acrylate such as an ethoxyethyl group Non-branching acrylamide, N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, etc. Amino (meth) acrylate, vinyl acetate, styrene, and the like. These can be used alone or in combination Use more than two types.

The polymerization method of the (meth) acrylate polymer (A) may be a random copolymer or a block copolymer.

The weight average molecular weight of the (meth) acrylate polymer (A) is from 800,000 to 3,000,000, preferably from 900,000 to 2,500,000, particularly preferably from 1,200,000 to 2,000,000. The weight average molecular weight in the present specification is a value in terms of polystyrene measured by a gel permeation chromatography (GPC) method.

When the weight average molecular weight of the (meth) acrylate polymer (A) is less than 800,000, the durability of the obtained adhesive is inferior. Further, when the weight average molecular weight of the (meth) acrylate polymer (A) exceeds 3,000,000, the adhesive strength of the obtained adhesive is lowered.

Further, in the adhesive composition P, the (meth) acrylate polymer (A) may be used alone or in combination of two or more. Further, the adhesive composition P may further contain a (meth) acrylate polymer which does not contain the above-described alicyclic structure-containing monomer as a constituent monomer unit.

(2) bridging agent (B)

The bridging agent (B) may be a reactive bridging agent which is reactive with a reactive functional group (hydroxyl group, amino group, or the like) of the (meth) acrylate polymer (A), and examples thereof include isocyanates. Bridging agent, epoxy bridging agent, amine bridging agent, melamine bridging agent, aziridine bridging agent, anthraquinone bridging agent, aldehyde bridging agent, oxazoline bridging agent, metal alkoxide bridging agent, Metal chelate bridging agent, metal salt bridging agent, ammonium salt bridging agent, and the like. Among them, the isocyanate-based bridging agent is excellent in reactivity with the fluorenyl group of the decane coupling agent (C), and when the (meth) acrylate polymer (A) has a hydroxyl group, The advantage of excellent reactivity of a hydroxyl group. The bridging agent (B) may be used singly or in combination of two or more.

The isocyanate bridging agent is a bridging agent containing at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as methylphenyl diisocyanate, diphenylmethane diisocyanate and xylene diisocyanate, and aliphatic polyisocyanates such as hexamethylene diisocyanate and isophor. Examples of the alicyclic polyisocyanate such as keto diisocyanate and hydrogenated diphenylmethane diisocyanate, and the biuret or isocyanate of these, and further examples thereof include ethylene glycol, propylene glycol, neopentyl glycol, and trimethylolpropane. An additive such as castor oil or the like which is a reactant containing a low molecular weight active hydrogen compound. Among them, trimethylolpropane-modified aromatic polyisocyanate is preferred from the viewpoint of reactivity with a hydroxyl group, and particularly, trimethylolpropane-modified xylene diisocyanate is preferable.

The content of the bridging agent (B) in the adhesive composition P is preferably 0.05 parts by mass to 3 parts by mass, particularly preferably 0.08 parts by mass, per 100 parts by mass of the (meth) acrylate polymer (A). 1.5 parts by mass, more preferably 0.3 to 1 part by mass. When the content of the bridging agent (B) is 0.05 parts by mass or more, the effect of improving the durability by the bridging agent (B) can be obtained. When the content of the bridging agent (B) exceeds 3 parts by mass, the degree of bridging is excessive, and the adhesion of the obtained adhesive may be lowered.

(3) decane coupling agent (C)

In the present embodiment, the decane coupling agent (C) has a functional thiol group capable of reacting with an organic material. The above-mentioned adhesive composition P is bridged, and the thiol group of the decane coupling agent (C) is reacted with the reactive functional group of the bridging agent (B). Especially in the bridging agent (B) In the case of an isocyanate-based bridging agent, the thiol group of the decane coupling agent (C) and the isocyanate group of the isocyanate-based bridging agent are likely to form a thiourethane bond. On the other hand, the other reactive functional group of the bridging agent (B) (isocyanate group of the isocyanate-based bridging agent) reacts with the reactive functional group (hydroxyl group, amino group, etc.) of the (meth) acrylate polymer (A). The (meth) acrylate polymer (A) is bridged to form a three-dimensional network structure. Further, the alkoxymethyl sulfonyl group of the decane coupling agent (C) is kept at a suitable distance from the (bridged) (meth) acrylate polymer (A) to be suspended from the (meth) acrylate polymer. The form on (A) thus exerts an excellent coupling effect. The adhesive obtained as described above is excellent in adhesion, and is excellent in adhesion durability even under high temperature conditions or under moist heat conditions.

In the case where the bridging agent (B) is an isocyanate bridging agent, the fluorenyl coupling agent (C) has a mercapto group which is easily reacted with an isocyanate group of an isocyanate bridging agent, so that the (meth) acrylate polymer (A) The reactive functional group can be obtained only from a hydroxyl group which is difficult to function in a general decane coupling agent (the (meth) acrylate polymer (A) may not contain a carboxyl group as a reactive functional group). The coupling effect of the decane coupling agent (C).

The decane coupling agent (C) is an organic ruthenium compound having at least one fluorenyl group in the molecule and having at least one alkoxycarbenyl group, and has good compatibility with the binder component and has light permeability, for example, preferably The one is transparent.

Specific examples of the above decane coupling agent (C) include 3-mercaptopropyltrimethoxydecane, 3-mercaptopropyltriethoxydecane, and 3-mercaptopropyldimethoxymethylnonane. a low molecular weight decane coupling agent containing a mercapto group; 3-mercaptopropyltrimethoxydecane, 3-mercaptopropyltriethoxydecane, A mercapto group-containing decane compound such as 0-mercaptopropyl dimethoxymethyl decane, and methyl triethoxy decane, ethyl triethoxy decane, methyl trimethoxy decane, ethyl trimethoxy decane, etc. A mercapto group-containing oligomer-type decane coupling agent such as a copolycondensate of an alkyl group-containing decane compound. In particular, from the viewpoint of improving durability, an oligomer-type decane coupling agent containing a mercapto group is preferable, and a mercapto compound containing a mercapto group and a copolycondensate containing an alkyl nonane compound are particularly preferable, and 3-mercaptopropyl group is further more preferable. A copolycondensate of a trimethoxy decane and methyl triethoxy decane. These may be used alone or in combination of two or more.

In the above fluorenyl group-containing oligomer-type decane coupling agent, the thiol group equivalent in the oligomer is preferably from 100 g/mol to 1000 g/mol, particularly preferably from 200 g/mol to 900 g/mol, further preferably 300 g/mol. 700 g/mol. If the thiol equivalent is less than 100 g/mol, the durability may be lowered. When the thiol equivalent exceeds 1000 g/mol, there is a possibility that the adhesion is lowered or the peeling is poor.

The content of the decane coupling agent (C) in the adhesive composition P is preferably 0.01 parts by mass to 5 parts by mass based on 100 parts by mass of the (meth) acrylate polymer (A), and particularly preferably 0.02 parts by mass to 3 parts by mass, more preferably 0.2 parts by mass to 0.8 parts by mass. When the content of the decane coupling agent (C) is less than 0.01 parts by mass, it is difficult to obtain the effect by the decane coupling agent (C). On the other hand, when the content of the decane coupling agent (C) exceeds 5 parts by mass, the reaction between the bridging agent (B) and the (meth) acrylate polymer (A) may be lowered.

(4) Various additives

The adhesive composition P may be added with various additives commonly used in acrylic adhesives, such as a charge preventive agent, an adhesion-imparting agent, an oxidation preventive agent, an ultraviolet absorber, a light stabilizer, a softener, and the like, as needed. Filler, refractive index modifier, and the like.

Examples of the antistatic agent include an ionic liquid, an ionic solid, an anionic surfactant, a ruthenium metal salt, a cationic surfactant, and a nonionic surfactant. Among them, an ionic liquid or an ion is preferably used. At least one selected from the group consisting of a solid and a base metal salt.

The ionic liquid and the ionic solid are preferably a nitrogen-containing phosphonium salt, a sulfur-containing xanthine salt, a phosphorus-containing phosphonium salt or the like. Further, the base metal salt is preferably a lithium salt, a potassium salt or the like. These may be used alone or in combination of two or more.

The content of the antistatic agent in the adhesive composition P is preferably 0.5% by mass to 8% by mass, and particularly preferably 1% by mass to 5% by mass. When the content of the antistatic agent is within the above range, the balance between the charging prevention performance and the durability of the adhesive is improved.

[Method for Producing Adhesive Composition]

The adhesive composition P can be obtained by producing the (meth) acrylate polymer (A), and the obtained (meth) acrylate polymer (A), the bridging agent (B), and the decane coupling agent (C). Mixing, at the same time, adding additives as needed to manufacture.

The (meth) acrylate polymer (A) can be produced by polymerizing a monomer constituting the polymer (in the case of a copolymer, a mixture of monomers) by a usual radical polymerization method. The polymerization of the (meth) acrylate polymer (A) can be carried out by a solution polymerization method or the like using a polymerization initiator as needed. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, and isobutyl acetate. Toluene, acetone, hexane, methyl ethyl ketone or the like may be used in combination of two or more.

The polymerization initiator may, for example, be an azo compound or an organic peroxide, and two or more kinds thereof may be used in combination. The azo compound may, for example, be 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile) or 1,1'-azobis(cyclohexane). 1-nitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile) , dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanoshikimate), 2,2'-azobis(2- Hydroxymethylpropionitrile, 2,2'-azobis[2-(2-imidazolin-2-yl)propane, and the like.

Examples of the organic peroxide include benzamidine peroxide, t-butyl peroxybenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, and di-n-propylperoxy. Dicarbonate, bis(2-ethoxyethyl)peroxydicarbonate, tert-butyl peroxy neopentate, tert-butyl peroxypivalate, (3,5,5-trimethyl Benzyl) peroxide, dipropylene peroxide, diethyl hydrazine peroxide, and the like.

Further, in the above polymerization step, the weight average molecular weight of the obtained polymer can be adjusted by mixing a chain shifting agent such as 2-mercaptoethanol.

After obtaining the (meth) acrylate polymer (A), a bridging agent (B), a decane coupling agent (C), a diluent solvent, and, if necessary, a solution of the (meth) acrylate polymer (A) are added. The additive was added and thoroughly mixed to obtain a tackifying composition P (coating solution) diluted with a solvent.

As a diluent solvent for diluting the adhesive composition P to obtain a coating solution, an aliphatic hydrocarbon such as hexane, heptane or cyclohexane; an aromatic hydrocarbon such as toluene or xylene; methylene chloride and two may be used. Halogenation of ethyl chloride Hydrocarbon; alcohol such as methanol, ethanol, propanol, butanol or 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, cyclohexanone Examples; esters such as ethyl acetate and butyl acetate; and cellosolve solvents such as ethyl cellosolve.

The concentration and viscosity of the coating solution thus prepared are not particularly limited as long as they are within the range of application, and may be appropriately selected depending on the case. For example, the concentration of the adhesive composition P can be diluted to 10% by mass to 40% by mass. Further, when the coating solution is obtained, the addition of a diluent solvent or the like is not a requirement, and the adhesive composition P may be added as long as it is a coating viscosity. In this case, the adhesive composition P can be directly used as a coating solution.

[adhesive]

The adhesive according to the present embodiment is obtained by bridging the adhesive composition P. The bridging of the adhesive composition P can be carried out by heat treatment. Further, this heat treatment can also serve as a drying treatment for volatilizing a diluent solvent or the like of the adhesive composition P.

In the case of heat treatment, the heating temperature is preferably from 50 ° C to 150 ° C, particularly preferably from 70 ° C to 120 ° C. Further, the heating time is preferably from 10 seconds to 10 minutes, particularly preferably from 50 seconds to 2 minutes. More preferably, after the heat treatment, the ripening period is allowed to stand at room temperature (for example, 23 ° C, 50% RH) for 1 to 2 weeks.

By the above heat treatment (and aging), the (meth) acrylate polymer (A) is bridged to the bridging agent (B) to form a three-dimensional network structure. Further, the thiol group of the decane coupling agent (C) is reacted with a reactive functional group of the bridging agent (B), and the alkoxymethyl sulfonyl group of the decane coupling agent (C) utilizes the above-mentioned bridging agent (B), Acrylic acid The ester polymer (A) or the above three-dimensional network structure exists at a suitable distance and exhibits an excellent coupling effect.

The adhesive obtained by bridging the adhesive composition P passes through the alicyclic structure of the (meth) acrylate polymer (A) and the action of the decane coupling agent (C), for a polarizing plate, etc. In particular, the optical member of the polycycloolefin has high adhesion to the transparent conductive film, and exhibits excellent adhesion durability even under high temperature conditions or under moist heat conditions. For example, it can prevent and suppress the occurrence of floating, peeling, bubbles, and the like under high temperature conditions of 85 ° C or under hot humid conditions of 60 ° C and 90% RH for 500 hours.

The gel fraction of the adhesive according to the present embodiment is preferably 30% to 95%, particularly preferably 40% to 90%, and more preferably 70% to 85%. When the gel fraction is less than 30%, the cohesive force of the adhesive is insufficient, and durability and reworkability are deteriorated. On the other hand, if the gel fraction is more than 95%, the adhesive force becomes too low, and the durability may be lowered. In addition, the gel fraction is a value stored in an environment of 23° C. and 50% RH for 7 days (after the ripening period has elapsed) from the time of formation of the adhesive layer. When it is not known whether it is a ripening period, if it is stored in the environment of 23 ° C and 50% RH for 7 days, the gel fraction may be within the above range.

The adhesive according to the present embodiment is suitably used for an optical member, and is particularly suitable for use in a polarizing plate, for example, bonding between optical members such as a polarizing plate (polarizing film) and a phase difference plate (phase difference film). Or a polarizing plate (polarizing film) and a phase difference plate (phase difference film) are bonded to the glass substrate.

Here, a polarizing plate having a polycycloolefin film (hereinafter referred to as a "COP polarizing plate") or the like has a large contact angle (for example, 95° or more). Moreover, the dimensional change (shrinkage rate) is large. Therefore, in general, the adhesiveness of the adhesive is low, and the problem of floating and peeling easily occurs on the interface with the adhesive. However, the adhesive agent according to the present embodiment exhibits excellent adhesion and durability to such a polycycloolefin film and a COP polarizing plate.

[bonding sheet]

As shown in Fig. 1, the adhesive sheet 1A according to the first embodiment is laminated on the release sheet 12, the adhesive layer 11 laminated on the release surface of the release sheet 12, and the laminate layer 1A in the order from the bottom to the top. The substrate 13 on the adhesive layer 11 is composed of a substrate 13 .

Further, as shown in Fig. 2, the adhesive sheet 1B according to the second embodiment is formed by the two release sheets 12a and 12b and the peeling surfaces of the two release sheets 12a and 12b. The adhesive layer 11 held by the two release sheets 12a and 12b is formed. In addition, the peeling surface of the peeling sheet in this specification is the surface which has the peeling property in the peeling sheet, and the surface which carried out the peeling process, and the surface which shows the peeling-

In both of the adhesive sheets 1A and 1B, the adhesive layer 11 is composed of an adhesive formed by bridging the above-mentioned adhesive composition P.

Although it is suitably determined for the purpose of use, it is usually in the range of 5 μm to 100 μm, preferably 10 μm to 60 μm. For example, when it is used as an optical member, particularly as an adhesive layer for a polarizing plate, it is preferably 10 μm to 50 μm, and particularly preferably 15 μm to 30 μm.

The base material 13 is not particularly limited, and any substrate used as a base material sheet of a usual adhesive sheet can be used. For example, in addition to the desired optical member, woven or non-woven fabrics using rayon, acryl, and polyester such as fibers; synthetic paper; upper paper, cellophane, impregnated paper, and copper paper may be exemplified. Paper such as aluminum; metal foil such as aluminum or copper; foam of urethane foam or polyethylene foam; polyethylene terephthalate or polybutylene terephthalate Polyester film of ester, polyethylene naphthalate, etc.; cellulose film of polyurethane film, polyethylene film, polypropylene film, triacetyl cellulose, polyvinyl chloride film, polyvinylidene chloride film, poly a plastic film such as a vinyl alcohol film, an ethylene-vinyl acetate film, a polystyrene film, a polycarbonate film, an acrylic film, a norbornene resin film, or a cycloolefin resin film; or two or more of these Laminated body, etc. The plastic film may be a uniaxially rolled film or a biaxially rolled film.

Examples of the optical member include a polarizing plate (polarizing film), a polarizer, a retardation film (retardation film), a viewing angle compensation film, a brightness enhancement film, a contrast film, a liquid crystal polymer film, a diffusion film, and a half. Through a reflective film or the like. As the polarizing plate, a polarizing plate in which a triacetyl cellulose (TAC) film is bonded to both sides of a polyvinyl alcohol-based polarizer, or a TAC film on one side is changed to a polarizing plate of a cycloolefin polymer film (COP polarized light) Board) and so on. In particular, the polycycloolefin film or the COP polarizing plate is not only easy to shrink, but also has a large dimensional change, and has a large contact angle and low adhesion. Therefore, it is suitable for forming the bonding of the present embodiment from the viewpoint of adhesion and durability. The object of the agent (the above-mentioned adhesive layer 11).

The thickness of the base material 13 varies depending on the type thereof. However, in the case of, for example, an optical member, it is usually 10 μm to 500 μm, preferably 50 μm to 300 μm, and particularly preferably 80 μm to 150 μm.

As the release sheets 12, 12a, 12b, for example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, or the like can be used. Polyethylene terephthalate Glycol ester film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene-(meth)acrylic acid copolymer Film, ethylene-(meth)acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, and the like. In addition, these bridge films can also be used. Further, these may be laminated films.

It is preferable that the peeling surface of the peeling sheet (particularly the surface in contact with the adhesive layer 11) is subjected to a peeling treatment. Examples of the release agent used for the release treatment include a release agent of an alkyd, an anthrone, a fluorine, an unsaturated polyester, a polyolefin, and a wax.

The thickness of the release sheets 12, 12a, and 12b is not particularly limited, but is usually about 20 μm to 150 μm.

In the production of the above-mentioned adhesive sheet 1A, the solution (coating solution) containing the adhesive composition is applied and heat-treated on the peeling surface of the release sheet 12, and after the adhesive layer 11 is formed, the bonding is performed. On the agent layer 11, the substrate 13 is laminated. Then, it is preferred to retain the ripening time. Further, the conditions regarding the heat treatment and the ripening are as described above.

Further, in the production of the above-mentioned adhesive sheet 1B, the coating solution containing the above-mentioned adhesive composition is applied and heat-treated on the peeling surface of one of the release sheets 12a (or 12b), and after the formation of the adhesive layer 11, On the adhesive layer 11, the peeling surface of the other release sheet 12b (or 12a) is polymerized.

As a method of applying the above coating solution, for example, a bar coating method, a knife coating method, a roll coating method, a plate coating method, a die coating method, a gravure coating method, or the like can be used.

The adhesive layer 11 in the adhesive sheets 1A and 1B has a haze value (a value measured according to JIS K7136:2000) of preferably 1.0% or less, particularly preferably 0.9% or less, and further preferably 0.8% or less. When the haze value is 1.0% or less, the transparency is extremely high, and it becomes an adhesive layer suitable for optical use.

Here, for example, in the liquid crystal display device including the liquid crystal module and the polarizing plate, a polarizing plate is used as the substrate 13 of the bonding sheet 1A, and the peeling sheet 12 of the bonding sheet 1A is peeled off to be exposed. The adhesive layer 11 and the liquid crystal module may be attached.

Further, for example, in a liquid crystal display device in which a retardation plate is disposed between a liquid crystal cell and a polarizing plate, as an example, first, one peeling sheet 12a (or 12b) of the bonding sheet 1B is peeled off, and the bonding sheet 1B is peeled off. The exposed adhesive layer 11 and the phase difference plate are bonded together. Then, the release sheet 12 of the adhesive sheet 1A using the polarizing plate as the base material 13 is peeled off, and the adhesive layer 11 exposed by the adhesive sheet 1A and the phase difference plate are bonded together. Further, the other release sheet 12b (or 12a) is peeled off from the adhesive layer 11 of the adhesive sheet B, and the adhesive layer 11 from which the adhesive sheet B is exposed is bonded to the liquid crystal module.

According to the above-mentioned adhesive sheets 1A and 1B, the adhesive layer 11 is excellent in adhesion and durability to an optical member such as a polarizing plate, and thus exhibits high adhesive force, even under high temperature conditions or hot and humid conditions. It is possible to prevent and suppress the occurrence of floating, peeling, foaming, and the like.

In the adhesive sheets 1A and 1B according to the present embodiment, it is preferable that the transparent conductive film is used as an adherend. In this case, the (meth) acrylate polymer (A) in the adhesive composition P preferably does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer. Thereby, it is possible to suppress the transparent conductive film strip due to the acid component Bad influence. Specifically, it is possible to suppress the occurrence of corrosion of the transparent conductive film or the change in the resistance value of the transparent conductive film. Further, the adhesive (adhesive layer 11) according to the present embodiment can exhibit the above-described excellent adhesion and durability without containing a carboxyl group.

Examples of the transparent conductive film include metals such as platinum, gold, silver, and copper; oxides such as tin oxide, indium oxide, cadmium oxide, zinc oxide, and zinc oxide; and indium tin oxide (ITO) of tin. Indium oxide of zinc oxide, indium oxide of fluorine, tin oxide of antimony, tin oxide of fluorine, zinc oxide of aluminum, etc.; non-oxidized compound such as sulfide, antimony hexaboride, titanium nitride, titanium carbide, etc. A transparent conductive film composed of the like.

As the base material 13, the adhesive sheet 1A using a polarizing plate (hereinafter referred to as "adhesive layer polarizing plate") is used, and the adhesive force is preferably 0.1 N/25 mm to 25 N/25 mm with respect to the alkali-free glass. It is particularly preferably 2N/25 mm to 20 N/25 mm. When the adhesive force is within the above range, it is possible to prevent floating, peeling, or the like from being adhered to the adherend such as a glass plate. In addition, the adhesive force referred to here basically means the adhesive force measured by the 180° peeling method based on JIS Z0237:2009, but the measurement sample is cut into a width of 25 mm and a length of 100 mm so that the measurement sample is opposed to the The adhesive was adhered at 0.5 MPa and 50 ° C for 20 minutes under pressure, and then allowed to stand under normal pressure of 23 ° C and 50% RH for 24 hours, and then the adhesive strength was measured at a peeling speed of 300 mm/min.

Further, the polarizing plate with the adhesive layer is attached to the adherend, and the adhesive force after standing for 2 days under normal pressure of 50 ° C and 50% RH is preferably 0.1 N / 25 mm to 25 N / 25 mm. It is particularly preferably 2N/25 mm to 20 N/25 mm. In this way, the increase in the adhesion force due to the passage of time is suppressed, Thus, the polarizing plate with the adhesive layer can be evaluated as a polarizing plate excellent in reworkability. In addition, the adhesive force referred to herein basically refers to the adhesive force measured by the 180° peeling method based on JIS Z0237:2009, but the measurement sample is cut into a width of 25 mm and a length of 100 mm so that the measurement sample is viscous with respect to the adhesion. After attaching at 0.5 MPa and 50 ° C for 20 minutes under pressure, the mixture was allowed to stand under the above conditions (normal pressure 50 ° C, 50% RH) for 2 days, and then the adhesion obtained by measurement was measured at a peeling speed of 300 mm/min.

The embodiments described above are described in order to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, each of the elements disclosed in the above embodiments includes all design changes and equivalents belonging to the technical scope of the present invention.

For example, the release sheet 12 of the adhesive sheet 1A can be omitted, and any one of the release sheets 12a and 12b in the adhesive sheet 1B can be omitted.

[Examples]

The present invention will be specifically described by the following examples, but the scope of the present invention is not limited by the examples and the like.

[Example 1]

1. Modulation of (meth) acrylate polymer

74 parts by mass of n-butyl acrylate, 5 parts by mass of methyl acrylate, 20 parts by mass of isobutyl acrylate, and 2-acrylic acid were placed in a reaction vessel including a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube. 1 part by mass of hydroxyethyl ester, 200 parts by mass of ethyl phthalate, and 0.08 parts by mass of 2,2'-azobisisobutyronitrile, and the air in the reaction container was replaced with nitrogen. The reaction solution was heated to 60 ° C while stirring in the nitrogen atmosphere to carry out the reaction. After 16 hours, it was cooled to room temperature. Here, the molecular weight of a part of the obtained solution was measured by the method described later, and it was confirmed that the (meth)acrylate polymer (A) having a weight average molecular weight (Mw) of 1.85 million was produced.

2. Modulation of adhesive composition

100 parts by mass of the (meth) acrylate polymer (A) obtained in the above step (1) (converted value of solid content; the same applies hereinafter); as a bridging agent (B), modified trimethylolpropane Toluene diisocyanate (manufactured by Soken Chemical Co., Ltd., trade name "TD-75") 0.4 parts by mass; as a decane coupling agent (C) having a mercapto group as a functional group reactive with an organic material, 3-mercaptopropyltrimethyl a copolycondensate of oxydecane and methyltriethoxy decane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "X41-1810", thiol equivalent: 450 g/mol) 0.3 parts by mass, mixed, and sufficiently stirred to pass acetic acid The ethyl ester was diluted to obtain a coating solution of the adhesive composition.

Here, the collocation of the adhesive composition is shown in Table 1. The details of the abbreviations and the like described in Table 1 are as follows.

[(Meth)acrylate polymer (A)]

BA: n-butyl acrylate

MA: methyl acrylate

HEA: 2-hydroxyethyl acrylate

IBXA: Isobutyl acrylate

ADMMA: adamantyl methacrylate

DCPA: Dicyclopentyl acrylate

CHA: cyclohexyl acrylate

PhEA: 2-phenoxyethyl acrylate

[Bridge agent (B)]

XDI: Trimethylolpropane modified xylene diisocyanate (manufactured by Soken Chemical Co., Ltd., trade name "TD-75")

TDI: Trimethylolpropane modified methyl phenyl diisocyanate (manufactured by Amika Chemical Co., Ltd., trade name "L-45")

[Hydrane coupling agent (C)]

C1: a copolycondensate of 3-mercaptopropyltrimethoxydecane and methyltriethoxydecane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "X41-1810", thiol equivalent: 450 g/mol)

C2: 3-mercaptopropyltrimethoxydecane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-803")

C3: 3-glycidoxypropyltrimethoxydecane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403")

3. Manufacture of polarizer with adhesive layer

The coating solution of the obtained adhesive composition was peeled off by the one side of the polyethylene terephthalate film by the ketone type release agent (The Linde Co., Ltd. product, The peeling-treated surface of SP-PET3811, thickness: 38 μm) was applied by a knife coater to a thickness of 25 μm after drying, and then an adhesive layer formed by heat treatment at 90 ° C for 1 minute.

Next, using a triethylene fluorene cellulose film to protect one surface of a polarizer composed of a polyvinyl alcohol film, and a COP polarizing plate having a thickness of 100 μm obtained by protecting the other surface with a cycloolefin polymer film, adhered to the above-mentioned viscous film. The adhesive layer is formed by bringing the exposed surface of the adhesive layer into contact with the surface of the cycloolefin polymer film, and then placing it in a 23° C. and 50% RH environment for 7 days for aging. To the polarizing plate with the adhesive layer.

[Examples 2 to 15, Comparative Examples 1 to 3]

In addition to the type and ratio of each monomer constituting the (meth) acrylate polymer (A), the weight average molecular weight of the (meth) acrylate polymer (A), the bridging agent (B), and the decane coupling agent The type and amount of (C) were changed as shown in Table 1, and a polarizing plate with an adhesive layer was produced in the same manner as in Example 1. In addition, in the fourth embodiment and the twelfth embodiment, an adhesive composition further containing a pyridinium salt (trade name "IL-P18" manufactured by Kyoei Chemical Co., Ltd.) was used as the antistatic agent.

Here, the above-mentioned weight average molecular weight (Mw) is a polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement).

<Measurement conditions>

‧GPC measuring device: manufactured by Tosoh, HLC-8020

‧GPC column (the following sequence is passed): Tosoh company

TSK guard column HXL-H

TSK gel GMHXL (×2)

TSK gel G2000HXL

‧ Determination of flux: tetrahydrofuran

‧Measurement temperature: 40 ° C

[Test Example 1] (Measurement of gel fraction)

In the examples or comparative examples, instead of using the polarizing plate used for the polarizing plate with the adhesive layer, one side of the polyethylene terephthalate film was peeled off with an anthrone-based release agent. Treated peeling sheet System, SP-PET3801, thickness: 38μm), the production of adhesive sheets. Specifically, on the exposed adhesive layer of the constituent body composed of the release sheet/adhesive layer (thickness: 25 μm) obtained in the production process of the example or the comparative example, the side surface of the peeled surface was treated. In the manner of connection, the above-mentioned release sheets are laminated. Thus, an adhesive sheet formed of a structure of a release sheet/adhesive layer/release sheet was produced.

The obtained adhesive sheet was aged at 23 ° C and 50% RH for 7 days. Thereafter, the adhesive sheet was made into a sample having a size of 80 mm × 80 mm, and the adhesive layer was wrapped with a polyester mesh (mesh size 200), and only the quality of the adhesive was weighed with a precision balance. The mass at this time is taken as M1.

Next, the above-mentioned polyester net-wrapped adhesive was immersed in ethyl acetate for 24 hours at room temperature (23 ° C). Thereafter, the adhesive was taken out, air-dried for 24 hours in an environment of a temperature of 23 ° C and a relative humidity of 50%, and further dried in an oven at 80 ° C for 12 hours. Only the quality of the dried adhesive was weighed with a precision balance. The mass at this time is taken as M2. The gel fraction (%) is represented by (M2/M1) × 100. The results are shown in Table 2.

[Test Example 2] (Measurement of haze value)

As the measurement sample, the same adhesive sheet as that used for the measurement of the gel fraction (which has been cooked for 7 days) was prepared. The haze value (%) of the adhesive layer (thickness: 25 μm) of the adhesive sheet was measured using a haze meter (NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.) based on JIS K7136:2000. The results are shown in Table 2.

[Test Example 3] (Measurement of adhesion)

A polarizing plate with an adhesive layer obtained in the examples or the comparative examples was cut to prepare a sample having a width of 25 mm and a length of 100 mm. The release sheet was peeled off from the sample, and the exposed adhesive layer was passed through an alkali-free glass (manufactured by Corning Incorporated, Eagle XG). After the sample was attached, the pressure cooker manufactured by Kurihara Co., Ltd. was pressurized at 0.5 MPa and 50 ° C for 20 minutes. Thereafter, after standing for 24 hours (1 day) or leaving for 14 days under conditions of 23 ° C and 50% RH, a tensile tester (Tensilon, manufactured by Orient, Inc.) was used, based on JIS Z0237:2009, at a peeling speed. The adhesion was measured under conditions of 300 mm/min and a peeling angle of 180° (adhesion force after 1 day of attachment and 14 days after attachment; N/25 mm). The results are shown in Table 2, respectively.

[Test Example 4] (durability evaluation)

The polarizing plate with an adhesive layer obtained in the examples or the comparative examples was cut to prepare a sample having a size of 233 mm × 309 mm. As a sample, a sample which was stored in an environment of 23° C. and 50% RH for 7 days was prepared from a polarizing plate (forming an adhesive layer) having an adhesive layer. The peeling sheet was peeled off from the sample, and the exposed adhesive layer was attached to an alkali-free glass (Eagle XG, manufactured by Corning Co., Ltd.), and then pressed at a pressure of 0.5 MPa and 50 ° C using a pressure cooker manufactured by Kurihara. 20 minutes.

After that, it was placed in an environment of the endurance conditions described below, and after 500 hours, the presence or absence of floating or peeling was confirmed using a magnifying glass of 10 times. The evaluation criteria are as follows. The results are shown in Table 2.

◎: No lifting or peeling was confirmed.

○: It was confirmed that the float or peeling was 0.5 mm or less.

×: Float or peeling of a size of 0.6 mm or more was confirmed.

<endurance condition>

‧85°C dry

‧60 ° C, relative humidity 90% RH

【Table 1】

As can be seen from Table 2, the adhesion of the adhesive layer obtained in the examples The agent has high adhesion (adhesion) and excellent durability.

[Industrial Availability]

The adhesive of the present invention is suitable for optical members, particularly for bonding of polarizing plates, and the adhesive sheet of the present invention is suitably used as an optical member, and is particularly suitable as an adhesive sheet for a polarizing plate.

1A‧‧‧bonding strip

11‧‧‧Adhesive layer

12‧‧‧ peeling film

13‧‧‧Substrate

Claims (12)

An adhesive composition characterized by having a weight average molecular weight of 800,000 to 3,000,000, comprising: a (meth) acrylate polymer (A) as a monomer unit constituting a polymer, having an alicyclic form a monomer of the structure; a bridging agent (B); and a decane coupling agent (C) having a mercapto group as a functional group reactive with an organic material. The adhesive composition according to claim 1, wherein the (meth) acrylate polymer (A) contains 0.1% by mass to 30% by mass as a monomer unit constituting the polymer. A monomer of the above alicyclic structure. The adhesive composition according to claim 1, wherein the alicyclic structure contains a cyclohexyl skeleton, a dicyclopentadiene skeleton, an adamantane skeleton or an isobornyl skeleton. The adhesive composition according to claim 1, wherein the (meth) acrylate polymer (A) further contains 0.1% by mass to 10% by mass as a monomer unit constituting the polymer. A monomer having a hydroxyl group. The adhesive composition according to claim 1, wherein the (meth) acrylate polymer (A) does not substantially contain a monomer having a carboxyl group as a monomer unit constituting the polymer. The adhesive composition according to claim 1, wherein the bridging agent (B) is an isocyanate bridging agent. The adhesive composition according to the above aspect of the invention, wherein the content of the decane coupling agent (C) in the adhesive composition is relative to the (meth) acrylate polymer (A) 100 parts by mass, 0.01 parts by mass to 5 Parts by mass. An adhesive comprising a bonding agent comprising the adhesive composition according to any one of claims 1 to 7. An adhesive sheet characterized in that it is an adhesive sheet having a substrate and an adhesive layer, and the adhesive layer is composed of the adhesive described in claim 8 of the patent application. The adhesive sheet according to claim 9, wherein the substrate is an optical member. The adhesive sheet according to claim 10, wherein the optical member is a polarizing plate. An adhesive sheet comprising: two release sheets; and an adhesive sheet of an adhesive layer held by the release sheet in contact with the release surfaces of the two sheets, wherein the adhesive layer is The composition of the adhesive described in claim 8 of the patent application.