TW201439253A - Adhesive composition, adhesive and adhesive sheet - Google Patents

Abstract

This invention provides an adhesive composition without negative effects on adhered objects such as the transparent conductive film caused by acid ingredients and having an excellent durability, an adhesive and an adhesive sheet. To address the subject mentioned above, provided is an adhesive composition with a weight average molecular weight of 1.5 to 2.5 million, comprising: the (meth)acrylate ester polymer (A) as the monomer unit constituting the polymer, containing the hydroxyl-containing monomer and the aromatic ring-containing monomer and not containing the carboxyl-containing monomer; and the isocyanate ester crosslinker (B). The (meth)acrylate ester polymer (A) as the monomer unit constituting the polymer contains 1-10 mass% of the hydroxyl-containing monomer and 1-10 mass% of the aromatic ring-containing monomer.

Description

Adhesive composition, adhesive and adhesive sheet

The present invention relates to an adhesive composition for attaching to a transparent conductive film, an adhesive (a material for bridging the adhesive composition), and an adhesive sheet, in particular, a suitable one for attaching to a polarizing plate. Adhesive compositions, adhesives, and adhesive sheets on optical components.

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 spacers, and the periphery thereof is sealed to hold the liquid crystal between the two transparent electrode substrates. The components of the material. Usually, on the outer side of the two transparent electrode substrates in the liquid crystal module, the polarizing plates are bonded to the polarizing plates.

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

[Previous Technical Literature] [Patent Literature]

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

In the touch panel as described above, it is presumed that a polarizing plate of the liquid crystal display device is interposed between the adhesive layer and a transparent conductive film (ITO). In this structure, although the adhesive is in direct contact with the ITO, since the adhesive in Patent Document 1 contains a carboxyl group (acid component), there is a problem that the ITO is etched or the ITO resistance value is changed.

At the same time, with the thinning of mobile electronic devices in recent years, the polarizing plates of the constituent members thereof have also been thinned. Specifically, a polarizing plate in which the thickness of the protective film of the polarizing polyvinyl alcohol is reduced on both sides is used. Since such a polarizing plate protective film has a weak ability to prevent thermal contraction of a polarizer, it tends to have a large heat shrinkage. Moreover, as a material of the above protective film, it is also suitable to replace it with triacetyl cellulose. An optical functional film or the like which is deaerated such as a cycloolefin polymer is likely to be produced. Therefore, the adhesive to be used thereon is required to have higher reliability (durability) than the present.

As a method of improving the durability of the adhesive, a monomer having a high glass transition point (Tg) of the formed individual polymer is generally copolymerized using a constituent component of a (meth)acrylic polymer. However, as described above, the thinned polarizing plate generates a large shrinkage stress under heat-resistant conditions, and in the adhesive layer designed to have a high glass transition point, it is difficult to alleviate the shrinkage stress, and the liquid crystal module or the like is deformed. Thereby, the assembly gap of the end portion of the liquid crystal display device is widened, thereby adversely affecting the display property.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an adhesive composition, an adhesive, and a paste which are excellent in durability without adversely affecting an adherend such as a transparent conductive film by an acid component. Pick up.

In order to achieve the above object, first, the present invention provides an adhesive composition characterized in that its weight average molecular weight is from 1,000,000 to 2.5 million, and comprises: (meth) acrylate polymer (A) as a constituent The monomer unit of the polymer contains a monomer having a hydroxyl group and a monomer having an aromatic ring, and does not contain a monomer having a carboxyl group; an isocyanate-based bridging agent (B). The (meth) acrylate polymer (A) contains, as a monomer unit constituting the polymer, 1% by mass to 10% by mass of a monomer having the above hydroxyl group, and 1% by mass to 10% by mass of the content. A monomer of an aromatic ring (Invention 1).

In the adhesive composition according to the invention (Invention 1), since the (meth) acrylate polymer (A) does not contain a monomer having a carboxyl group, the acid component is not supplied to the transparent conductive film or the like. Adhesives have an adverse effect. In addition, the above The (meth) acrylate polymer (A) contains a predetermined amount of a monomer having a hydroxyl group and a monomer having an aromatic ring, and the obtained adhesive has high durability.

In the above invention (Invention 1), the content of the isocyanate-based bridging agent (B) in the adhesive composition is preferably 0.1% by mass based on 100 parts by mass of the (meth)acrylate polymer (A). Parts to 1 part by mass (Invention 2).

In the above invention (Invention 1, Invention 2), it is preferable to further contain a decane coupling agent (C) having a mercapto group which is a functional group reactive with an organic material (Invention 3).

Secondly, the present invention provides an adhesive comprising the above-mentioned adhesive composition (Invention 1 to Invention 3). (Invention 4).

Thirdly, the present invention provides a bonding sheet which is an adhesive sheet having a substrate and an adhesive layer, and the adhesive layer is composed of the above-mentioned adhesive (Invention 4) (Invention 5).

Fourthly, the present invention provides a transparent conductive film attaching adhesive sheet characterized in that the adhesive layer is composed of the above-mentioned adhesive (Invention 4) as a bonding sheet having a substrate and an adhesive layer. A transparent conductive film is attached to the surface and the reverse surface which are in contact with the substrate of the above-mentioned adhesive layer (Invention 6).

In the above invention (Invention 6), the transparent conductive film is preferably made of indium tin oxide (Invention 7).

In the above invention (Invention 5 to Invention 7), the substrate is preferably an optical member (Invention 8).

In the above invention (Invention 8), the optical member is preferably a polarizing plate (Invention 9).

Fifth, the present invention provides an adhesive sheet characterized in that: The adhesive layer of the peeling sheet is sandwiched between the two release sheets and the release surface of the two release sheets, and the adhesive layer is composed of the above-mentioned adhesive (Invention 4) (Invention 10).

In the above invention (Invention 5 to Invention 10), when the laminate obtained by bonding the above-mentioned adhesive layer and the transparent conductive film is exposed to a moist heat promotion test for 500 hours in an atmosphere of 65 ° C and 95% RH, The increase rate of the electric resistance value calculated by the following chemical formula is preferably 10% or less (Invention 11).

Resistance increase rate (%) = {(RR ₀ ) / R ₀ } × 100

(wherein R ₀ is the initial resistance value before the moist heat promotion, and R is the resistance value after the moist heat promotion)

Since the (meth) acrylate polymer of the adhesive composition of the present invention does not contain a monomer having a carboxyl group, it does not adversely affect the adherend such as a transparent conductive film due to the acid component. Further, the (meth) acrylate polymer contains a predetermined amount of a monomer having a hydroxyl group and a monomer having an aromatic ring, and the obtained adhesive has high durability.

1A, 1B‧‧‧bonding strips

1A'‧‧‧Polarizer with adhesive layer

11‧‧‧Adhesive layer

12,12a,12b‧‧‧ peeling film

13‧‧‧Substrate

13’‧‧‧Polar plate

21‧‧‧PET film

21a, 21b‧‧‧

22‧‧‧ITO film

22a‧‧‧ face

23‧‧‧ glass plate

23a‧‧‧ face

24‧‧‧Adhesive tape

25‧‧‧Electrode

30‧‧‧Digital altimeter

S‧‧‧Resistance measurement sample

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.

Fig. 3 is a cross-sectional view showing a sample for measuring a resistance value produced in Test Example 6.

Fig. 4 is a perspective view showing the test method in Test Example 6.

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 1,000,000 to 2.5 million, and contains a (meth) acrylate polymer (A) and an isocyanate. The bridging agent (B), the above (meth) acrylate polymer (A), as a monomer unit constituting the polymer, contains a monomer having a hydroxyl group (containing a hydroxyl group monomer) and a monomer having an aromatic ring (containing a fragrance) The ring monomer) does not contain a monomer having a carboxyl group (containing a carboxyl group monomer). In addition, the (meth) acrylate polymer (A) contains 1% by mass to 10% by mass of a monomer having a hydroxyl group as a monomer unit constituting the polymer, and contains 1% by mass to 10% by mass of an aromatic ring. 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".

In the above-mentioned adhesive composition P, since the (meth) acrylate polymer (A) does not contain a carboxyl group-containing monomer having an acid component, it is possible to suppress corrosion of the transparent conductive film to be attached or resistance of the transparent conductive film. The value has changed. Further, the (meth) acrylate polymer (A) has a certain amount of a monomer having a hydroxyl group and a monomer having an aromatic ring, and the obtained adhesive has both cohesive force and stress relaxation property, and durability is improved. .

The (meth) acrylate polymer (A), as a monomer unit constituting the polymer, preferably has an alkyl group having 1 to 20 carbon atoms, in addition to the monomer having a hydroxyl group and a monomer having an aromatic ring. The alkyl (meth)acrylate is particularly preferably contained as a main component. Further, other monomers (except for the monomer having a carboxyl group) may be contained as needed.

(meth) acrylate polymer (A) as a constituent of the polymer The monomer unit can exhibit excellent adhesion by an alkyl (meth)acrylate having an alkyl group and having 1 to 20 carbon atoms. 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 50% by mass to 98% 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 70% by mass to 96% by mass, and more preferably 80% by mass to 94% by mass.

The (meth) acrylate polymer (A), as a monomer unit constituting the polymer, contains a monomer having a hydroxyl group, and the hydroxyl group has high reactivity with an isocyanate group of the isocyanate-based bridging agent (B), and these reactions are high. The (meth) acrylate polymer (A) is bridged due to the isocyanate bridging agent (B). By this bridge structure, the gel fraction can be controlled to a predetermined value, and an adhesive excellent in durability can be obtained.

As the hydroxyl group-containing monomer, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, or (meth)acrylic acid 3- Hydroxypropyl (meth) acrylate hydroxyalkyl group, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate An ester or the like, among which 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred from the viewpoint of reactivity with the isocyanate-based bridging agent (B), and particularly preferred (A) Base) 2-hydroxyethyl acrylate. These may be used alone or in combination of two or more.

The (meth) acrylate polymer (A) contains 1% by mass to 10% by mass of the hydroxy group-containing monomer as the monomer unit constituting the polymer, and preferably contains 2% by mass to 8% by mass, particularly preferably It is 2.5% 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 1% by mass, the bridging point is too small, and the obtained adhesive does not exhibit excellent 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 is lowered.

The (meth) acrylate polymer (A), as a monomer unit constituting the polymer, contains a monomer having an aromatic ring, and the adhesive thus obtained, particularly for the use of a cycloolefin-containing polymer The polarizing plate of the protective film (hereinafter referred to as a "COP polarizing plate") is excellent in durability.

Examples of the aromatic ring-containing monomer include phenyl (meth)acrylate, 2-phenethyl (meth)acrylate, benzyl (meth)acrylate, and naphthyl (meth)acrylate. Phenylethyl acrylate, butyl phenoxy (meth) acrylate, ethoxylated o-phenyl phenol acrylate, phenoxy diglycol (meth) acrylate, ethylene oxide Cresol (meth) acrylate, ethylene oxide (EO) Among the modified nonylphenol (meth) acrylates and the like, 2-phenethyl (meth)acrylate is preferred from the viewpoint of polymerizability. These may be used alone or in combination of two or more.

The (meth) acrylate polymer (A) contains, as a monomer unit constituting the polymer, 1% by mass to 10% by mass of a monomer having an aromatic ring, and preferably contains 2% by mass to 8% by mass, particularly preferably It is contained in an amount of 3% by mass to 5% by mass. When the content of the aromatic ring-containing monomer is in the above range, the obtained adhesive exhibits excellent stress relaxation property and cohesive force, and is excellent in durability. When the content of the monomer containing an aromatic ring is less than 1% by mass, the obtained adhesive may cause light leakage when used for a polarizing plate or the like. On the other hand, when the content of the aromatic ring-containing monomer exceeds 10% by mass, the durability of the obtained adhesive is lowered.

The monomer other than the above-mentioned other monomer is preferably a monomer which does not contain a functional group reactive with the isocyanate-based bridging agent (B) so as not to interfere with the reaction of the hydroxyl group-containing hydroxyl group with the isocyanate-based bridging agent (B). Examples of such a monomer include a (meth)acrylic acid alkoxyalkyl ester such as methoxyethyl (meth)acrylate or ethoxyethyl (meth)acrylate; (meth)acrylate having an aliphatic ring such as cyclohexyl acrylate; non-branching acrylamide such as acrylamide or methacrylamide; N,N-dimethyl (meth)acrylate A (meth) acrylate having a non-branching tertiary amino group such as an aminoethyl group or an N,N-dimethylaminopropyl (meth)acrylate, vinyl acetate, styrene or the like. These may be used alone or in combination of two or more.

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

The (meth) acrylate polymer (A) has a weight average molecular weight of from 1,000,000 to 2.5 million, preferably from 1.5 million to 2.2 million, particularly preferably from 1.8 million 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 1,000,000, the durability of the obtained adhesive is inferior. Further, when the weight average molecular weight of the (meth) acrylate polymer (A) exceeds 2.5 million, the stress relaxation property 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 monomer containing no hydroxyl group and/or a monomer containing an aromatic ring as a (meth)acrylate polymer constituting a monomer unit.

The adhesive composition P contains an isocyanate-based bridging agent (B), but the isocyanate-based bridging agent (B) has an advantage of being excellent in reactivity with a hydroxyl group contained in the (meth)acrylate polymer (A).

The isocyanate-based bridging agent (B) contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include an aromatic polyisocyanate such as methylphenyl diisocyanate, diphenylmethane diisocyanate or benzodiamethylene diisocyanate; and an aliphatic polyisocyanate such as hexamethylene diisocyanate. Examples of the alicyclic polyisocyanate such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, and the titration tube and isocyanate of these, further include ethylene glycol, propylene glycol, neopentyl glycol, and trimethylol. An adduct such as propane or castor oil and a reactant containing a low molecular weight active hydrogen compound. its Among them, trimethylolpropane-modified aromatic polyisocyanate is preferred from the viewpoint of durability in the case of use in a COP polarizing plate, and particularly, trimethylolpropane-modified benzenedimethylene diisocyanate is preferable. The above-mentioned isocyanate-based bridging agent (B) may be used alone or in combination of two or more.

The content of the isocyanate-based bridging agent (B) in the adhesive composition P is preferably 0.1 parts by mass to 1 part by mass, particularly preferably 0.2% by mass based on 100 parts by mass of the (meth) acrylate polymer (A). It is preferably 0.5 parts by mass, more preferably 0.3 parts by mass to 0.4 parts by mass. When the content of the isocyanate-based bridging agent (B) is within the above range, the obtained adhesive forms a bridging structure excellent in stress relaxation property and durability.

The adhesive composition P preferably further contains a decane coupling agent, and particularly preferably a decane coupling agent containing a sulfhydryl group as a functional group reactive with an organic material (hereinafter referred to as a "decane coupling agent (C)" ). Since the sulfhydryl group readily reacts with the isocyanate group of the isocyanate-based bridging agent (B), the bridging functional group of the (meth) acrylate polymer (A) is in a general decane coupling agent, even if it is only compatible with a hydroxyl group which is difficult to act (( The methyl acrylate polymer (A), as a bridging functional group, can obtain a coupling effect by a decane coupling agent (C) even if it does not contain a carboxyl group.

When the adhesive composition P containing a decane coupling agent (C) is bridged, the thiol group of the decane coupling agent (C) and the isocyanate group of the isocyanate-based bridging agent (B) are likely to form a thiourethane bond. The other isocyanate group of the isocyanate-based bridging agent (B) reacts with the hydroxyl group of the (meth) acrylate polymer (A) to bridge the (meth) acrylate polymer (A) to form a three-dimensional network structure. Moreover, it is presumed that the alkoxymethyl sulfonyl group of the decane coupling agent (C) maintains a suitable distance from the (bridged) (meth) acrylate polymer (A) (the isocyanate bridging agent (B) The distance between the isocyanate groups is a shape suspended on the (meth) acrylate polymer (A). Thereby, an excellent coupling effect is exhibited, and the obtained adhesive is also an adhesive agent excellent in adhesion durability under high temperature conditions or wet heat conditions. This effect is particularly remarkable when the attachment target of the adhesive is an inorganic material such as glass or metal.

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

Specific examples of the above-described decane coupling agent (C) include a mercapto group such as 3-mercaptopropyltrimethoxydecane, 3-mercaptotrimethylethoxydecane, or 3-mercaptomethyldimethoxydecane. Low molecular type decane coupling agent; 3-mercaptopropyltrimethoxydecane, 3-mercaptotrimethylethoxydecane, 3-mercaptomethyldimethoxydecane, etc. A thiol-containing oligomer such as a copolycondensate of an alkyl group-containing decane compound such as methyl ethoxy decane, ethyl trimethyl ethoxy decane, methyl trimethoxy decane or ethyl trimethoxy decane a decane coupling agent or the like. In particular, from the viewpoint of improving durability, an oligomer-type decane coupling agent containing a mercapto group is preferable, and a copolycondensate of a mercapto compound containing a mercapto group and a cyanide compound containing an alkyl group is particularly preferable, and 3-mercaptopropyltrimethyl group is further more preferable. A copolycondensate of oxydecane with methyltrimethylethoxysilane. These may be used alone or in combination of two or more.

The content of the decane coupling agent (C) in the adhesive composition P is preferably 0.01 parts by mass to 1 part by mass based on 100 parts by mass of the (meth) acrylate polymer (A), and particularly preferably It is 0.05 parts by mass to 0.8 parts by mass, and more preferably 0.1 parts by mass to 0.5 parts by mass. The content of the decane coupling agent (C), such as If it is less than 0.01 parts by mass, it is difficult to obtain the effect brought about by the decane coupling agent (C). On the other hand, when the content of the decane coupling agent (C) exceeds 1 part by mass, the reaction with the isocyanate bridging agent (B) and the (meth) acrylate polymer (A) may be hindered.

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

[Method for Producing Adhesive Composition]

The adhesive composition P can be obtained by mixing the obtained (meth) acrylate polymer (A) and the isocyanate bridging agent (B) by producing a (meth) acrylate polymer (A), and, if necessary, Adding additives to make.

The (meth) acrylate polymer (A) can be produced by polymerizing a mixture of monomer units constituting the polymer 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, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, and the like, and two or more kinds thereof may be used in combination.

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'-azo double (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), an isocyanate bridging agent (B), a diluent solvent, and, if necessary, an additive are added to the solution of the (meth) acrylate polymer (A). The mixture was 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. Halogenated hydrocarbon such as ethyl chloride; alcohol such as methanol, ethanol, propanol, butanol or 1-methoxy-2-propanol; acetone, methyl ethyl ketone, 2-pentanone, isophorone a ketone such as cyclohexanone; an ester such as ethyl acetate or butyl acetate; a cellosolve solvent 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. In addition, when a coating solution is obtained, addition of a diluent solvent or the like is obtained. It is not a requirement, and the adhesive composition P may be a coating solvent, and the dilution solvent may not be added. In this case, the adhesive composition P can be directly used as a coating solution.

[adhesive]

The adhesive agent according to the present embodiment is obtained by bridging the adhesive composition P. The adhesive according to the present embodiment has a transparent conductive film as one of the attachment targets.

The bridging of the adhesive composition P can be carried out by heat treatment. In addition, this heat treatment can also serve as a drying treatment for volatilizing a dilution 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 30 seconds to 10 minutes, and particularly preferably from 50 seconds to 2 minutes. More preferably, after the heat treatment, the ripening period is left at a normal temperature (for example, 23 ° C, 50% RH) for about 1 to 2 weeks.

By the above heat treatment (and aging), the (meth) acrylate polymer (A) is bridged to the isocyanate bridging agent (B) to form a three-dimensional network structure.

The storage modulus (G') at 23 ° C is preferably 0.05 MPa to 0.20 MPa, particularly preferably 0.08 MPa to 0.18 MPa, and more preferably 0.1 MPa to 0.15 MPa. Further, the storage modulus (G') at 80 ° C of the adhesive according to the present embodiment is preferably 0.05 MPa to 0.15 MPa, particularly preferably 0.07 MPa to 0.15 MPa, and further preferably 0.08 MPa to 0.13 MPa. . When the storage modulus (G') at 23 ° C and 80 ° C is within the above range, the desired stress relaxation property and cohesive force are obtained, and when applied to an optical member such as a polarizing plate, the endurance ring is used. Under the environment (for example, at a high temperature of 80 ° C), it is possible to effectively prevent floating, peeling, and the like from occurring on the interface of the optical member or the interface of the glass substrate. Further, the storage modulus is a value measured by a torsional shearing method at a measurement frequency of 1 Hz based on JIS K7244-6.

The gel fraction of the adhesive according to the present embodiment is preferably 30% to 98%, particularly preferably 80% to 95%. 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 exceeds 98%, the adhesive strength is too low and there is a possibility that the durability is lowered.

Further, the gel fraction of the adhesive is a value at the time of attachment (after the ripening period). Specifically, it means the gel fraction after the adhesive composition is applied and heat-treated on a release sheet, and stored in an environment of 23° C. and 50% RH for 7 days (cooking). This is because the gel fraction of the adhesive varies depending on the value before the ripening period. From this point of view, in the case where it is not known whether or not it is a mature period, it is only necessary to store the gel fraction within the above range after storage for 7 days in an environment of 23 ° C and 50% RH.

[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 mentioned in this specification, It is a surface which has peeling property in a peeling sheet, and includes the surface which carried out the peeling process, and the surface which shows the peeling property, even if it is a peeling process.

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.

The thickness of the adhesive layer 11 is appropriately determined depending on the purpose of use of the adhesive sheets 1A and 1B, but 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 a desired optical member, a woven fabric or a non-woven fabric using rayon, acryl, or polyester; a synthetic paper; a paper of a top quality paper, a cellophane, an impregnated paper, a copper paper, or the like; a metal foil such as aluminum or copper; a foam such as a urethane foam or a polyethylene foam; polyethylene terephthalate, polybutylene terephthalate or polynaphthalene Polyester film such as acid glycol ester; cellulose film such as polyurethane film, polyethylene film, polypropylene film, triacetyl cellulose; polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, A plastic film such as an ethylene-vinyl acetate film, a polystyrene film, a polycarbonate film, an acrylic film, a norbornene resin film, or a cycloolefin resin film; or a laminate of two or more of these. 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 phase difference plate (phase difference film), and a viewing angle compensation film. A luminance film, a contrast-enhancing film, a liquid crystal polymer film, a diffusion film, a semi-transmissive reflection film, and the like. In particular, since the polarizing plate (polarizing film), in particular, the COP polarizing plate is easily shrunk and has a large dimensional change, it is preferable to form the bonding agent (the above-mentioned adhesive layer 11) as described in the present embodiment from the viewpoint of durability. The substrate.

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 film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, vinyl acetate film, ionomer resin film, ethylene-( A methyl)acrylic copolymer film, an ethylene-(meth)acrylate copolymer film, a polystyrene film, a polycarbonate film, a polyimide film, a fluororesin film, or 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 peeling surface of the peeling sheet 12 Then, the solution (coating solution) containing the adhesive composition P is applied and heat-treated to form the adhesive layer 11, and then the substrate 13 is laminated on the adhesive layer 11. It is then preferred to retain the ripening period. 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 release surface of one release sheet 12a (or 12b) to form the adhesive layer 11, On the adhesive layer 11, the peeling surface of the other side 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, a method of manufacturing a touch panel will be described. The touch panel includes a liquid crystal module formed of a transparent conductive film on one side, a polarizing plate laminated on the transparent conductive film, and a polarizing plate laminated on the other surface of the liquid crystal module. In the first method, two sheets of the adhesive sheet 1A using the polarizing plate as the substrate 13 are prepared, and the release sheet 12 of the first bonding sheet 1A is peeled off, and the exposed adhesive layer 11 and the liquid crystal module are formed on one surface. The transparent conductive film is bonded together, and the release sheet 12 of the second adhesive sheet 1A is peeled off, and the exposed adhesive layer 11 and the other surface of the liquid crystal module are bonded together.

In the second method, two sheets of adhesive sheets 1B are prepared, and the first adhesive sheet is prepared. The one side release sheet 12a (or 12b) of 1B is peeled off, and the exposed adhesive layer 11 is bonded to a transparent conductive film formed on one surface of the liquid crystal element. Then, the one side release sheet 12a (or 12b) of the second bonding sheet 1B is peeled off, and the exposed adhesive layer 11 is bonded to the other surface of the liquid crystal module. Next, the other side release sheet 12b (or 12a) of the first adhesive sheet 1B is peeled off, and the exposed adhesive layer 11 is bonded to the polarizing plate. Similarly, the other side release sheet 12b (or 12a) of the second adhesive sheet 1B is peeled off, and the exposed adhesive layer 11 is bonded to the polarizing plate.

According to the above-mentioned adhesive sheets 1A and 1B, since the adhesive layer 11 is excellent in durability, it is possible to prevent and suppress floating, peeling, and hairing between the substrate 13 and the adherend even under high temperature conditions or under moist heat conditions. The occurrence of bubbles, etc. In particular, when a COP polarizing plate is used as the substrate 13, the stress generated by the deformation of the COP polarizing plate can be absorbed and relaxed in the adhesive layer 11, thereby exhibiting excellent durability.

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. Since the (meth) acrylate polymer (A) in the adhesive composition P does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer, it is possible to suppress the introduction of the acid component to the transparent conductive film. Bad effects. Specifically, it is possible to suppress corrosion of the transparent conductive film or change the resistance value of the transparent conductive film.

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-oxidation of sulfide, lanthanum hexaboride, titanium nitride, titanium carbide, etc. a transparent conductive film composed of a substance or the like.

The laminate obtained by laminating the adhesive layer 11 and the transparent conductive film was subjected to a wet heat endurance test in a weather at 65 ° C and 95% RH for 500 hours. In the case of the following transparent conductive film formula, the increase rate of the electric resistance value is preferably 10% or less, particularly preferably 9% or less, and further preferably 8% or less.

Resistance increase rate (%) = {(RR ₀ ) / R ₀ } × 100

(In the formula, R ₀ is the resistance value before the damp heat endurance test, and R is the resistance value after the damp heat endurance test.)

When the resistance value increase rate is 10% or less, it is considered that the conductivity of the transparent conductive film is not substantially lowered, and the function of the touch panel is not hindered.

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. Particularly preferably 2N/25mm~ 20N/25mm. By suppressing the increase in the adhesive force generated over time, 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

Into a reaction vessel including a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube, 87.5 parts by mass of n-butyl acrylate, 5 parts by mass of methyl acrylate, and 5 mass of 2-phenylethyl acrylate were charged. 2.5 parts by mass of 2-hydroxyethyl acrylate, 200 parts by mass of ethyl acetate, and 0.08 parts by mass of 2,2'-azobisisobutyronitrile, replacing the air in the reaction vessel with nitrogen gas. The reaction solution was heated to 60 ° C while stirring in a nitrogen atmosphere, and the reaction was allowed to proceed for 16 hours, followed by cooling 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 2 million was formed.

2. Modulation of adhesive composition

100 parts by mass of the (meth) acrylate polymer (A) obtained in the above step (1) (converted solid content; the same applies hereinafter); as an isocyanate bridging agent (B), trimethylolpropane was changed. Benzene dimethylene diisocyanate (manufactured by Mitsui Takeda Chemical Co., Ltd., trade name "takenateD110N") 0.20 parts by mass; as a decane coupling agent (C), 3-mercaptopropyltrimethoxy decane and methyltriethoxy 0.30 parts by mass of a copolycondensate of a decane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "X41-1810") was mixed, sufficiently stirred, and diluted with ethyl acetate to obtain a coating solution of the adhesive composition.

Here, the combination 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]

BA: n-butyl acrylate

MA: methyl acrylate

PhEA: 2-phenoxyethyl acrylate

HEA: 2-hydroxyethyl acrylate

4HBA: 4-hydroxybutyl acrylate

AA: Acrylic

3. Manufacture of polarizer with adhesive layer

Applying the coating solution of the obtained adhesive composition to poly(terephthalic acid) One surface of the ethylene glycol ester film was coated on a peeling-treated surface of a release sheet (SP-PET3811, thickness: 38 μm, manufactured by Linde Co., Ltd.) which was subjected to a release treatment with an anthrone-based release agent, and coated with a knife coater. After the thickness of the dried layer was 25 μm, the adhesive layer was 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 brought into contact with the exposed surface of the adhesive layer and the surface of the cycloolefin polymer film, and then placed in a 23 ° C, 50% RH environment for 7 days for aging, thereby obtaining an adhesive layer. Polarizer.

[Examples 2 to 14, Comparative Examples 1 to 4]

In the same manner as in Example 1, except that the type and ratio of each monomer constituting the (meth) acrylate polymer (A) and the amount of the isocyanate-based bridging agent (B) were changed as shown in Table 1. The operation was carried out to manufacture a polarizing plate with an adhesive layer.

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 Corporation, HLC-8020

. GPC column (the following sequence is passed): made by Tosoh

TSK guard column HXL-H

TSK gel GMHXL (×2)

TSK gel G2000HXL

. Determination of flux: tetrahydrofuran

. Measuring 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. The treated release sheet (SP-PET3801, thickness: 38 μm, manufactured by Linde Co., Ltd.) was used to produce a bonded sheet. 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 1.

[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. About the adhesive layer of the adhesive sheet (thickness: The haze value (%) was measured based on JIS K7136:2000 using a haze meter (NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.). The results are shown in Table 1.

[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 peeling sheet was peeled off from the sample, and the sample was attached to the glass without the enamel glass (manufactured by Corning Co., Ltd., Eagle XG), and the pressure cooker manufactured by Kurihara Co., Ltd. was used at 0.5 MPa. Pressurize at 50 ° C for 20 minutes. Thereafter, after standing for 24 hours under conditions of 23 ° C and 50% RH, a tensile tester (Tensilon, manufactured by Orui Co., Ltd.) was used, and based on JIS Z0237:2009, a peeling speed of 300 mm/min and a peeling angle of 180° were used. The conditions were determined for the adhesion (adhesion after 1 day of attachment; N/25 mm).

Further, the sample was pressed at 0.5 MPa and 50 ° C for 20 minutes as described above, and after being attached to the above-mentioned flawless glass, it was allowed to stand for 2 days under normal pressure of 50 ° C and 50% RH. The adhesion at this time was measured in the same manner (adhesion force after 2 days of attachment; N/25 mm). The results are shown in Table 1, 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 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 following durable conditions, and after 250 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 1.

◎: 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

[Test Example 5] (Measurement of storage modulus)

In Test Example 1, an adhesive sheet composed of a release sheet/adhesive layer/release sheet was produced in the same manner. The release sheet was peeled off from the adhesive sheet so that the thickness of the adhesive layer was 3 mm, and a plurality of layers were laminated. A hole of a cylindrical body (height 3 mm) having a diameter of 8 mm was punched out on the obtained laminate of the adhesive layer, and this was used as a sample.

For the above samples, the storage modulus (MPA) was measured using a viscoelasticity meter (DYNAMIC ANALAYZER, manufactured by REOMETRIC Co., Ltd.) using the torsional shear method under the following conditions in accordance with JIS K7244-6. The results are shown in Table 1.

Measurement frequency: 1 Hz

Measurement temperature: 23 ° C, 80 ° C

[Test Example 6] (Measurement of resistance value increase rate)

The polarizing plate with the adhesive layer obtained in the examples or the comparative examples was measured for the resistance value according to the following test method, and the increase rate of the resistance value was calculated.

As shown in FIG. 3, a cross-sectional view of the sample S is measured for the resistance value. Poly terephthalate formed of ITO film 22 on one side 21a is prepared by sputtering The ethylene glycol (PET) film 21 is bonded to the side 21b of the ITO film 22 of the PET film 21 and one side of the glass plate 23 by an adhesive tape 24 (manufactured by Linda Co., Ltd., trade name "Tackliner TL-70"). 23a joined.

Then, a conductive resin material containing silver (manufactured by Fujikura Kasei Co., Ltd., trade name "FA-301CA") is formed on the surface of the ITO film 22 that is in contact with the PET film 21 and the reverse side (hereinafter referred to as "one side") 22a. The Dotite touch panel circuit type has a square electrode shape of 20 mm × 5 mm, and after coating, it is heated at a temperature of 80 ° C for 20 minutes and then dried to form two electrodes 25 which become measurement points of resistance values. At this time, the distance between the two electrodes 25, 25 is adjusted to a position slightly larger than 20 mm.

On the other hand, the polarizing plate 1A' with the adhesive layer obtained in the examples or the comparative examples was cut at a size of 20 mm × 250 mm to peel off the release sheet (at this time, the adhesive layer was provided). The polarizing plate 1A' is a laminated body composed of a polarizing plate 13' and an adhesive layer 11. Thereafter, the adhesive layer 11 of the polarizing plate 1A' with the adhesive layer is adhered to the side 22a of the ITO film 22 along the edges of the two electrodes 25, 25 (not to be too tightly attached). In the polarizing plate 1A' of the adhesive layer, a sample S for measuring the resistance value shown in Fig. 3 was produced.

Then, as shown in FIG. 4, the initial resistance value R ₀ (Ω) between the electrodes 25 and 25 is measured by a digital altimeter (product name "3802-50" manufactured by HITA EE Co., Ltd.) 30. Further, the sample S for measuring the resistance value was allowed to stand in an environment of 60° C. and 90% RH for 500 hours, and then the resistance value R (Ω) after the moist heat promotion was measured. Based on the obtained initial resistance value R ₀ and the resistance value R after the moist heat promotion, the resistance value increase rate of the resistance value measurement sample S was calculated by the following formula. The results are shown in Table 1.

Resistance increase rate (%) = {(RR ₀ ) / R ₀ } × 100

As is clear from Table 1, the adhesive of the adhesive layer obtained in the examples can suppress the change in the resistance value of the transparent conductive film and is excellent in durability.

[Industrial Availability]

The adhesive and the adhesive sheet of the present invention are suitable for attachment to a transparent conductive film, particularly a transparent conductive film made of indium tin oxide (ITO), and an optical member, particularly to a polarizing plate.

1A‧‧‧bonding strip

11‧‧‧Adhesive layer

12‧‧‧ peeling film

13‧‧‧Substrate

Claims (11)

An adhesive composition characterized by having a weight average molecular weight of 1,000,000 to 2.5 million, comprising: a (meth) acrylate polymer (A) as a monomer unit constituting a polymer, and having a single group having a hydroxyl group The monomer and the monomer having an aromatic ring do not contain a monomer having a carboxyl group; the isocyanate bridging agent (B). The (meth) acrylate polymer (A) contains, as a monomer unit constituting the polymer, 1% by mass to 10% by mass of the monomer having a hydroxyl group, and contains 1% by mass to 10% by mass of the above aromatic ring. Monomer. The adhesive composition according to claim 1, wherein the content of the isocyanate bridging agent (B) in the adhesive composition is relative to the (meth) acrylate polymer (A) 100 parts by mass, from 0.1 part by mass to 1 part by mass. The adhesive composition according to claim 1, wherein the adhesive further comprises a decane coupling agent (C) having a mercapto group as a functional group reactive with an organic material. An adhesive obtained by bridging the adhesive composition described in claim 1 of the patent application. 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 4 of the patent application. A transparent conductive film attaching 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 4; The transparent conductive film is attached to the reverse side of the surface of the adhesive layer that is in contact with the substrate. The transparent conductive film attaching adhesive sheet according to claim 6, wherein the transparent conductive film is made of indium tin oxide. The adhesive sheet according to claim 5, wherein the substrate is an optical member. The adhesive sheet according to claim 8, 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 a release surface of the two release sheets, the adhesive The layer is composed of the adhesive described in claim 4 of the patent application. The adhesive sheet according to claim 5, wherein the laminate obtained by laminating the adhesive layer and the transparent conductive film is exposed in an atmosphere of 65 ° C and 95% RH. In the 500-hour wet heat promotion test, the increase rate of the electric resistance value calculated by the following chemical formula of the above transparent conductive film was 10% or less. The resistance value increase rate (%)={(RR ₀ )/R ₀ }×100 where R ₀ is the initial resistance value before the moist heat promotion, and R is the resistance value after the moist heat promotion.