TW201542662A - Adhesive composition, adhesive agent, and adhesive sheet - Google Patents

Abstract

An adhesive composition for constituting an adhesive agent that is brought into contact with a metallic member upon use, said adhesive composition comprising: a (meth)acrylic acid ester polymer (A) which contains a monomer having a hydroxy group in an amount of more than 15% by mass and 30% by mass or less and does not contain a monomer having a carboxyl group as the monomer constituting the polymer; and a benzotriazole-type anti-corrosive agent (B). The adhesive composition does not corrode a metallic member when the adhesive composition is in contact with the metallic member, and has excellent wet-heat blushing resistance.

Description

Adhesive composition, adhesive and adhesive sheet

The present invention relates to an adhesive and an adhesive sheet which are used in contact with a metal member, in particular, a metal mesh of a touch panel, and an adhesive composition constituting the adhesive.

In recent years, in various mobile electronic devices such as smart phones and tablet computers, the use of touch panels as displays has gradually increased. As a method of the touch panel, there are a resistive film method, a capacitive method, and the like. However, in the above mobile electronic device, a capacitive method is mainly used.

The electrode of a small touch panel used for a smart phone or the like is mostly composed of a transparent conductive film made of tin-doped indium oxide (ITO). However, since the resistance value of ITO is hard to be reduced to 10 Ω/□ or less, when ITO is used in a large electrode pattern, signal degradation occurs, and it is difficult to increase the size of the touch panel.

Therefore, copper which can reduce the resistance value to 10 Ω/□ or less has been attracting attention as an electrode material of a touch panel, and various copper electrodes have been studied. However, since copper is easily corroded compared to ITO, if the adhesive used for the ITO electrode is directly used for the copper electrode, the copper electrode is corroded. Therefore, an adhesive which does not corrode the copper electrode is required.

However, the touch panel is sometimes placed under high temperature and high humidity conditions, It has durability which can be used without any problem even under such conditions. However, in the conventional touch panel, when it is returned to normal temperature and normal humidity after high temperature and high humidity conditions, the problem of whitening (wet heat whitening) of the adhesive layer tends to occur.

Patent Document 1 discloses an adhesive attached to an electromagnetic wave shielding film, which is provided with a near-infrared absorbing dye to impart a near-infrared absorbing effect, and a benzotriazole compound to prevent deterioration of the near-infrared absorbing pigment. .

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 4818236

However, the adhesive of Patent Document 1 is used for an optical filter of a plasma display panel, and the adhesive cannot be applied to a touch panel having different uses. For example, if the adhesive is applied to a touch panel, the aforementioned problem of moist heat bleaching occurs.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an adhesive composition, an adhesive, and an adhesive sheet which are capable of suppressing corrosion of a metal member to be contacted and which are excellent in moist heat whitening resistance.

In order to achieve the above object, the present invention provides an adhesive composition for forming an adhesive for use in contact with a metal member, comprising: a (meth) acrylate polymer (A) as a constituent polymer Single list The monomer contains a hydroxyl group-containing monomer in an amount of more than 15% by mass and not more than 30% by mass, and does not contain a monomer having a carboxyl group; and a benzotriazole-based rust inhibitor (B) (Invention 1).

In the (meth) acrylate polymer (A) in the adhesive composition of the invention (Invention 1), a monomer containing the hydroxy group is contained as a monomer unit constituting the polymer in the above amount. The adhesive is excellent in resistance to moisture and heat whitening. On the other hand, as described above, when a predetermined amount of a hydrophilic group such as a hydroxyl group is present in the adhesive, water is easily absorbed into the adhesive, and the metal member in contact with the adhesive is easily corroded. However, the adhesive composition of the above invention (Invention 1) contains a benzotriazole-based rust preventive (B), whereby corrosion of the metal member to be contacted can be suppressed. Further, since the (meth) acrylate polymer (A) in the above-mentioned adhesive composition (Invention 1) does not contain a carboxyl group-containing monomer, corrosion of a metal member due to a carboxyl group (acid) can be prevented.

In the above invention (Invention 1), the benzotriazole-based rust inhibitor (B) contains a compound selected from the group consisting of 1H-benzotriazole, 1H-tolyltriazole, and 1-[N,N-bis(2- At least one of ethylhexyl)aminomethyl]benzotriazole and 1-[N,N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole is preferred (Invention 2) .

In the above-mentioned invention (Inventions 1 and 2), the (meth) acrylate polymer (A) contains, as a monomer unit constituting the polymer, a hard glass having a glass transition temperature of 70 ° C or higher. Monomers are preferred (Invention 3).

In the above invention (Inventions 1 to 3), in the (meth) acrylate polymer (A), 2-ethylhexyl (meth) acrylate is preferred as a monomer unit constituting the polymer ( Invention 4).

In the above invention (Inventions 1 to 4), the above adhesive composition It is preferred to further contain a crosslinking agent (C) (Invention 5).

Secondly, the present invention provides an adhesive which is obtained by crosslinking the above-mentioned adhesive composition (Inventions 1 to 5) (Invention 6).

In the above invention (Invention 6), a dielectric constant at 1.0 MHz is preferably 2.0 to 8.0 (Invention 7).

Thirdly, the present invention provides an adhesive sheet comprising: two release sheets; and an adhesive layer sandwiched by the release sheet in contact with the release faces of the two release sheets, the adhesive layer being Adhesive (Inventions 6, 7) constitute (Invention 8).

In the above invention (Invention 8), the pressure-sensitive adhesive layer is preferably placed on the touch panel so as to be in contact with the metal mesh (Invention 9).

According to the adhesive composition, the adhesive, and the adhesive sheet of the present invention, corrosion of the metal member to be contacted can be suppressed, and the wet heat whitening resistance is also excellent.

1‧‧‧Adhesive film

11‧‧‧Adhesive layer

12a, 12b‧‧‧ peeling film

2‧‧‧ touch panel

3‧‧‧Display body module

4‧‧‧Adhesive layer

5a‧‧‧1st film sensor

5b‧‧‧2nd film sensor

51‧‧‧Substrate film

52‧‧‧Electrode

6‧‧‧ Covering materials

7‧‧‧Printing layer

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

Fig. 2 is a cross-sectional view showing a configuration example of a touch panel.

Hereinafter, embodiments of the present invention will be described.

[adhesive composition]

The adhesive composition of the present embodiment (hereinafter referred to as "adhesive composition P") is an adhesive composition for constituting an adhesive used in contact with a metal member. As the metal member, a capacitive touch surface can be preferably exemplified The copper mesh as the electrode in the plate is not limited thereto.

The adhesive composition P contains a (meth) acrylate polymer (A), and contains, as a monomer unit constituting the polymer, more than 15% by mass and 30% by mass or less of a monomer having a hydroxyl group (hydroxyl-containing monomer). It is preferable that the monomer having no carboxyl group (carboxyl group-containing monomer) and the benzotriazole-based rust inhibitor (B) and the crosslinking agent (C) are further contained. In the present specification, (meth) acrylate means both acrylate and methacrylate. Other similar terms are also the same. Moreover, the concept of "copolymer" is also included in "polymer".

In the (meth) acrylate polymer (A) in the above adhesive composition P, as a monomer unit constituting the polymer, a hydroxyl group-containing monomer is contained in the above amount, and the obtained adhesive is applied at a high temperature. After high-humidity conditions (for example, 240 hours under conditions of 85 ° C and 85% RH), whitening at the time of returning to normal temperature and normal humidity is suppressed, that is, it is excellent in wet heat and whitening resistance. When the (meth) acrylate polymer (A) contains a hydroxyl group-containing monomer as a monomer unit in the above amount, a predetermined amount of a hydroxyl group remains in the obtained binder. The hydroxyl group is a hydrophilic group. If a certain amount of the hydrophilic group is present in the adhesive, the adhesive is immersed in the adhesive under the high temperature and high humidity conditions even under the condition of high temperature and high humidity. The compatibility of the water is also good, and as a result, the whitening of the adhesive is suppressed.

However, as described above, when a predetermined amount of a hydrophilic group is present in the adhesive, the adhesive easily absorbs water and easily corrodes the metal member in contact with the adhesive. However, the viscous composition P of the present embodiment contains the benzotriazole-based rust inhibitor (B), whereby corrosion of the metal member to be contacted can be suppressed.

In addition, by the presence of the benzotriazole-based rust inhibitor (B), The reactivity of the crosslinking agent (C) and the (meth) acrylate polymer (A) described later tends to decrease, but in the (meth) acrylate polymer (A), the above amount is used as a monomer unit. When the hydroxyl group-containing monomer is contained, the reaction of the crosslinking agent (C) and the (meth) acrylate polymer (A) can be favorably performed.

On the other hand, since the (meth) acrylate polymer (A) in the above-mentioned adhesive composition P does not contain a carboxyl group-containing monomer, corrosion of a metal member due to a carboxyl group (acid) can be prevented.

(1) (meth) acrylate polymer (A)

The hydroxyl group-containing monomer which is a monomer unit of the polymer contained in the (meth)acrylate polymer (A), for example, 2-hydroxyethyl (meth)acrylate, (meth) 2-hydroxypropyl acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate A hydroxyalkyl (meth) acrylate or the like. Among them, from the viewpoint of reactivity with a hydroxyl group and a crosslinking agent (C) and copolymerization with other monomers in the obtained (meth) acrylate polymer (A), (meth)acrylic acid 2- Hydroxyethyl ester is preferred. These may be used singly or in combination of two or more.

As described above, the (meth) acrylate polymer (A) contains, as a monomer unit constituting the polymer, more than 15% by mass and 30% by mass or less of the hydroxyl group-containing monomer. When the content of the hydroxyl group-containing monomer as a monomer unit in the (meth) acrylate polymer (A) is 15% by mass or less, the pressure-sensitive adhesive layer is inferior in moisture-heat-whitening resistance. On the other hand, when the content of the hydroxyl group-containing monomer exceeds 30% by mass, even if the benzotriazole-based rust inhibitor (B) is contained, the amount of water in the inhalation adhesive becomes too large, and the metal member is easily corroded.

From the viewpoint of the above, the (meth) acrylate polymer (A) preferably contains 16 to 25% by mass of the hydroxyl group-containing monomer as the monomer unit constituting the polymer, and particularly preferably 18 to 20% by mass. .

In the (meth) acrylate polymer (A), the monomer unit constituting the polymer does not contain a carboxyl group-containing monomer. Here, the phrase "the monomer having no carboxyl group" means that the monomer having a carboxyl group is not actually contained, and the degree of corrosion of the metal member which is not caused by the carboxyl group is allowed to be contained, except that the carboxyl group-containing monomer is not contained at all. Carboxyl containing monomer. Specifically, the (meth) acrylate polymer (A) is preferably contained in an amount of 0.1% by mass or less as a monomer unit, and is contained in an amount of 0.01% by mass or less.

In the (meth) acrylate polymer (A), as the monomer unit constituting the polymer, an alkyl (meth) acrylate having an alkyl group and having 1 to 20 carbon atoms is preferred. Thereby, the obtained adhesive can exhibit better adhesion. Further, the hard monomer described later is removed from the alkyl (meth)acrylate.

Examples of the (meth)acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include methyl acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and (meth)acrylic acid. Butyl ester, n-amyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, N-dodecyl (meth)acrylate, tetradecyl (meth)acrylate, cetyl (meth)acrylate, octadecyl (meth)acrylate, and the like. Among them, from the viewpoint of further improving the adhesion, a (meth) acrylate having an alkyl group having 1 to 8 carbon atoms is preferred, n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate. The ester is particularly preferred, and 2-ethylhexyl (meth)acrylate is further preferred. 2-(meth)acrylic acid 2- Ethylhexyl ester can reduce the dielectric constant of the obtained adhesive and can suppress the malfunction of the touch panel. Further, these may be used alone or in combination of two or more.

In the (meth) acrylate polymer (A), as a monomer unit constituting the polymer, an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms is 30 to 85% by mass. Preferably, it is preferably from 40 to 75% by mass, and further preferably from 50 to 65% by mass.

Further, in the (meth) acrylate polymer (A), a hard monomer having a glass transition temperature (Tg) of 70 ° C or higher as a homopolymer is preferable as a monomer unit constituting the polymer. By containing the above hard monomer as a monomer unit constituting the (meth) acrylate polymer (A), the cohesive force of the obtained adhesive is improved, and the durability is excellent. In particular, when 2-ethylhexyl (meth)acrylate is used as the monomer unit constituting the (meth)acrylate polymer (A), the cohesive force tends to decrease, and therefore it is preferred to use the above-mentioned hard monomer. The homopolymer of the above hard monomer has a glass transition temperature (Tg) of preferably 75 to 200 ° C, more preferably 80 to 180 ° C.

Examples of the hard monomer include methyl methacrylate (Tg 105 ° C), isobornyl acrylate (Tg 94 ° C), isobornyl methacrylate (Tg 180 ° C), propylene morpholine (Tg 145 ° C), and acrylic acid. Adamantyl ester (Tg 115 ° C), adamantyl methacrylate (Tg 141 ° C), dimethyl methacrylate (Tg 89 ° C), acrylamide (Tg 165 ° C) and the like. These may be used alone or in combination of two or more.

Among the above hard monomers, the viewpoint of further exerting the performance of hard monomers while preventing adverse effects on other properties such as adhesion and transparency Methyl methacrylate, isobornyl acrylate and propylene morpholine are preferred, and methyl methacrylate is particularly preferred.

In the (meth) acrylate polymer (A), the hard monomer is preferably contained in an amount of from 10 to 45% by mass, particularly preferably from 15 to 30% by mass, based on the monomer unit constituting the polymer. By containing 10% by mass or more of the above hard monomer, the effect of improving the durability based on the monomer unit can be expected. On the other hand, by setting the hard monomer to a content of 45% by mass or less, the relative shortage of the other monomer units in the (meth) acrylate polymer (A) can be prevented, and the obtained adhesion can be obtained. The agent is excellent in adhesion and resistance to moist heat whitening.

The (meth) acrylate polymer (A) may contain other monomers as a monomer unit constituting the polymer, as needed. As the other monomer, a monomer which does not contain a reactive functional group without impairing the action of the hydroxyl group-containing monomer is preferred. The other monomer may, for example, be an alkoxyalkyl (meth)acrylate such as methoxyethyl (meth)acrylate or ethoxyethyl (meth)acrylate or a cyclohexyl (meth)acrylate. (meth)acrylate having an aliphatic ring such as an ester, N-N-dimethylaminoethyl (meth)acrylate, N-N-dimethylaminopropyl (meth)acrylate, etc. having non-crosslinking A tertiary amino (meth) acrylate, vinyl acetate, styrene, and the like. These may be used singly 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 300,000 to 1,000,000, preferably 400,000 to 900,000, and preferably 500,000 to 700,000. Gel permeation chromatography The polystyrene-converted value measured by the (GPC) method.

The (meth) acrylate polymer (A) as the adhesive main component of the adhesive composition P has a weight average molecular weight of 300,000 or more, and the durability of the obtained adhesive is improved by (meth) The weight average molecular weight of the acrylate polymer (A) is 1,000,000 or less, and the coatability of the adhesive composition P becomes good.

Further, in the adhesive composition P, the (meth) acrylate polymer (A) may be used singly or in combination of two or more.

(2) benzotriazole-based rust inhibitor (B)

Examples of the benzotriazole-based rust inhibitor (B) include 1H-benzotriazole, 1H-tolyltriazole, and 1-[N,N-bis(2-ethylhexyl)aminomethyl]. Benzotriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole, carboxybenzotriazole, 2, 2'-[[(methyl-1H-) Benzotriazol-1-yl)methyl]imino] bisethanol and the like. Among them, 1H-benzotriazole, 1H-tolyltriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole and 1-[N,N-double (2 -Ethylhexyl)aminomethyl]methylbenzotriazole is preferred. According to these, in particular, corrosion of the metal member to be contacted can be effectively suppressed. The benzotriazole-based rust inhibitor (B) may be used singly or in combination of two or more.

The content of the benzotriazole-based rust inhibitor (B) in the adhesive composition P is preferably 0.01 to 2.0 parts by mass based on 100 parts by mass of the (meth) acrylate polymer (A), 0.05 to 0.05. 1.0 part by mass is particularly preferred, and 0.1 to 0.5 part by mass is further preferred. When the content of the benzotriazole-based rust inhibitor (B) is 0.01 parts by mass or more, the corrosion-inhibiting effect of the metal member can be sufficiently obtained. In addition, when the content of the benzotriazole-based rust inhibitor (B) is 2.0 parts by mass or less, Will not have an adverse effect on adhesion.

(3) Crosslinking agent (C)

It is preferred that the adhesive composition P contains a crosslinking agent (C). The (meth)acrylate copolymer (A) is crosslinked by the crosslinking agent (C) in the adhesive composition P to form a three-dimensional network structure, thereby improving the cohesive force of the obtained adhesive.

As the crosslinking agent (C), it may be reacted with a reactive group (hydroxy group as a monomer unit of a hydroxyl group-containing monomer) of the (meth) acrylate copolymer (A), for example, isocyanate crosslinking. Agent, epoxy crosslinking agent, amine crosslinking agent, melamine crosslinking agent, nitrogen-acrylic ring crosslinking agent, hydrazine crosslinking agent, aldehyde crosslinking agent, oxazoline crosslinking agent, metal An alkoxide-based crosslinking agent, a metal chelate-based crosslinking agent, a metal salt-based crosslinking agent, an ammonium salt-based crosslinking agent, and the like. Among the above substances, an isocyanate crosslinking agent which is excellent in reactivity with a hydroxyl group which the (meth)acrylate polymer (A) has is used is preferable. Further, the crosslinking agent (C) can be used alone or in combination of two or more.

The isocyanate crosslinking agent is a compound containing at least a polyisocyanate compound. The polyisocyanate compound may, for example, be an aromatic polyisocyanate such as toluene diisocyanate, diphenylmethane diisocyanate or xylene diisocyanate, or an aliphatic polyisocyanate such as hexamethylene diisocyanate or isophorone diisocyanate. An alicyclic polyisocyanate such as hydrogenated diphenylmethane diisocyanate, and the biuret and isocyanurate of the substance, in addition, ethylene glycol, propylene glycol, neopentyl glycol, and trishydroxyl The reactant of a low molecular weight active hydrogen compound such as propane or castor oil is also an adduct or the like. Among them, trimethylolpropane-modified aromatic polyisocyanate is preferred from the viewpoint of reactivity with a hydroxyl group, and tris-hydroxyl The propane-modified toluene diisocyanate is particularly preferred.

The content of the crosslinking agent (C) in the adhesive composition P is preferably 0.001 to 10 parts by mass based on 100 parts by mass of the (meth) acrylate polymer (A), and particularly preferably 0.01 to 5 parts by mass, 0.02~. 1 part by mass is further preferred.

When the content of the crosslinking agent (C) is within the above range, the obtained adhesive becomes a better cohesive force, and the durability of the adhesive is improved.

(4) Various additives

In the adhesive composition P, various additives generally used as a propylene-based adhesive can be added as needed, for example, a decane coupling agent, an antistatic agent, an adhesion promoter, an antioxidant, an ultraviolet absorber, a light stabilizer, and a softener. , a filler, a refractive index modifier, and the like.

In particular, from the viewpoint of improving durability, it is preferred to add a decane coupling agent as an additive to the adhesive composition P. The decane coupling agent is preferably an organic ruthenium compound having at least one alkoxycarbenyl group in the molecule and having good compatibility with the (meth) acrylate polymer (A). Further, when the adhesive sheet 1 is used for optical use, a light transmissive decane coupling agent is preferred.

Examples of the decane coupling agent (C) include a polymerizable unsaturated group-containing oxime compound such as vinyl trimethoxy decane, vinyl triethoxy decane or methacryloxypropyl trimethoxy silane. , an epoxy structure ruthenium compound such as 3-glycidyl ether propyl trimethoxy decane or 2-(3,4-epoxycyclohexyl)ethyltrimethoxy decane, 3-mercaptopropyltrimethoxydecane, 3 - Anthracenyl-containing fluorene compound such as mercaptopropyltriethoxydecane or 3-mercaptopropyldimethoxymethylnonane, 3-aminopropyltrimethoxydecane, N-(2-aminoethyl)-3- Aminopropyltrimethyl Aminoguanidine compound such as oxydecane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxydecane, 3-chloropropyltrimethoxydecane, 3-isocyanatepropyltriethoxy A decane or a condensate of at least one alkyl group-containing compound such as methyltriethoxydecane, ethyltriethoxydecane, methyltrimethoxydecane or ethyltrimethoxydecane. These may be used alone or in combination of two or more.

The decane coupling agent is preferably 0.01 to 1.0 part by mass, more preferably 0.05 to 0.5 part by mass, per 100 parts by mass of the (meth) acrylate polymer (A).

(5) Manufacture of adhesive composition

The adhesive composition P can produce the (meth) acrylate polymer (A) and mix the obtained (meth) acrylate polymer (A) and the benzotriazole rust inhibitor (B), and It is produced by adding a crosslinking agent (C) and an additive as needed.

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. The polymerization solvent may, for example, be ethyl acetate, n-butyl acetate, n-isobutyl acetate, toluene, acetone, hexane or methyl ethyl ketone, or two or more kinds thereof.

The polymerization initiator may, for example, be an azo compound or an organic peroxide, or two or more kinds thereof may be used in combination. As the azo compound, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane- 1-carboxonitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile ), 2,2'-azobis(2-methyl) Propionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-hydroxymethylpropionitrile), 2,2'-azobis[2 -(2-imidazolin-2-yl)propane] and the like.

The organic peroxide may, for example, be benzoic acid benzoate, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate or di-N-propyl peroxydicarboxylate. Carbonate, bis(2-ethoxyethyl)peroxydicarbonate, tert-butyl peroxy neodecanoate, tert-butyl peroxypivalate, (3,5,5-trimethylhexyl) Peroxide, dipropene peroxide, diethylperoxide peroxide, and the like.

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

After obtaining the (meth) acrylate polymer (A), a benzotriazole-based rust inhibitor (B) is added to the solution of the (meth) acrylate polymer (A) and a crosslinking agent (C) is added as needed. The additive and the diluent solvent are mixed and mixed, whereby an adhesive composition P (coating solution) diluted with a solvent is obtained.

As the diluent solvent, for example, an aliphatic hydrocarbon such as hexane, heptane or cyclohexane, an aromatic hydrocarbon such as toluene or xylene, or a chlorinated hydrocarbon such as dichloromethane or dichloroethane, methanol or ethanol can be used. , propanol, butanol, 1-methoxy-2-propanol and other alcohols, acetone, methyl ethyl ketone, 2-pentanone, isophorone, cyclohexanone and other ketones, ethyl acetate, acetic acid An ester such as an ester or a cellosolve such as an ethyl cellosolve is a solvent.

The concentration and viscosity of the coating solution thus prepared are not particularly limited as long as they are within the range that can be applied, and can be appropriately selected depending on the situation. For example, it is diluted so that the concentration of the adhesive composition P becomes 10 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 if the adhesive composition P is a coatable viscosity or the like, it may not be added. Dilute the solvent. In this case, the adhesive composition P is a coating solution in which a polymerization solvent of the (meth)acrylate polymer (A) is directly used as a diluent solvent.

[adhesive]

The adhesive of the present embodiment is obtained by crosslinking the adhesive composition P. The crosslinking of the adhesive composition P can be carried out by heat treatment. In addition, the drying treatment at the time of volatilizing the dilution solvent or the like of the adhesive composition P can also serve as the heat treatment.

When the heat treatment is performed, the heating temperature is preferably from 50 to 150 ° C, and particularly preferably from 70 to 120 ° C. Further, the heating time is preferably from 30 seconds to 10 minutes, and particularly preferably from 50 seconds to 2 minutes. After the heat treatment, if necessary, it may be set to a normal temperature (for example, 23 ° C, 50% RH) and a health period of about 1 to 2 weeks. When the conditioning period is required, an adhesive is formed after the passage of the wellness period, and the adhesive layer is formed after the heat treatment is completed without the need for a curing period.

The adhesive obtained by crosslinking the adhesive composition P can suppress corrosion of the metal member to be contacted by the benzotriazole-based rust inhibitor (B), and by the above (meth) acrylate polymer The hydroxyl group (A) has excellent moisture and heat whitening resistance.

The dielectric constant at 1.0 MHz of the adhesive of the present embodiment is preferably 2.0 to 8.0, more preferably 2.0 to 7.0, and still more preferably 2.0 to 6.0. By the dielectric constant of the adhesive being 2.0 to 8.0, it is possible to effectively suppress the malfunction of the touch panel caused by the adhesive. Moreover, the measuring method of the dielectric constant of an adhesive is shown by the test example mentioned later.

[adhesive sheet]

As shown in Fig. 1, the adhesive sheet 1 of the present embodiment is sandwiched between the two release sheets 12a and 12b by two release sheets 12a and 12b and in contact with the peeling surfaces of the two release sheets 12a and 12b. The adhesive layer 11 is formed. However, in the adhesive sheet 1, the peeling sheets 12a and 12b are not essential components, and are peeled off and removed when the adhesive sheet 1 is used. In addition, the peeling surface of the peeling sheet in this specification is a 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 property, even if it is not peeling process.

(1) Adhesive layer

The adhesive layer 11 is composed of an adhesive in which the above-mentioned adhesive composition P is crosslinked. The thickness of the adhesive layer 11 (value measured in accordance with JIS K7130) is preferably 10 to 300 μm, particularly preferably 25 to 250 μm, and further preferably 50 to 100 μm. When the thickness of the adhesive layer 11 is 10 μm or more, excellent adhesion can be sufficiently exhibited, and the thickness of the adhesive layer 11 is 300 μm or less, and the workability is improved. Further, when the thickness of the adhesive layer 11 is 25 to 100 μm, it is suitable for optical use, and is particularly intended for use as a touch panel. Further, the adhesive layer 11 may be formed of a single layer or may be formed by laminating a plurality of layers.

(2) peeling sheet

The release sheets 12a and 12b are not particularly limited, and a known plastic film can be used. For example, a polyethylene film, a polyacrylic film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, or a polyethylene terephthalate film can be used. , polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene / (meth) acrylic copolymer film, An ethylene/(meth)acrylate copolymer film, a polystyrene film, a polycarbonate film, a polyimide film, a fluororesin film, or the like. Further, a crosslinked film of these materials can also be used. In addition, a laminated film of these materials may also be used.

The release surface of the release sheets 12a and 12b (particularly the surface in contact with the adhesive layer 11) is preferably subjected to a release treatment. The release agent to be used for the release treatment may, for example, be a release agent such as an alkyd type, an anthrone type, a fluorine type, an unsaturated polyester type, a polyolefin type, or a wax type. In the release sheets 12a and 12b, one of the release sheets is a heavy release type release sheet having a large peeling force, and the other release sheet is preferably a light release type release sheet having a small peeling force.

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

(3) Manufacture of adhesive sheets

As a production example of the adhesive sheet 1, the coating liquid of the above-mentioned adhesive composition P is applied to the peeling surface of one of the release sheets 12a (or 12b), and heat treatment is performed to crosslink the adhesive composition P to form After the coating layer is applied, the peeling surface of the other peeling sheet 12b (or 12a) is superposed on the coating layer. In the case where a wellness period is required, the curing period is set in advance, and when the curing period is not required, the coating layer directly becomes the adhesive layer 11. Thereby, the above-mentioned adhesive sheet 1 can be obtained. The conditions regarding heat treatment and health maintenance are as described above.

In another example of the production of the adhesive sheet 1, the coating liquid of the adhesive composition P is applied onto the peeling surface of one of the release sheets 12a, and heat treatment is performed to crosslink the adhesive composition P to form a coating layer. A release sheet 12a with a coating layer was obtained. Further, the coating liquid of the adhesive composition P is applied onto the peeling surface of the other release sheet 12b, and heat treatment is performed to make the adhesive composition P The coating layer was formed to obtain a peeling sheet 12b with a coating layer. Then, the release sheet 12a with the coating layer and the release sheet 12b with the coating layer are bonded so that the two coating layers are in contact with each other. In the case where a wellness period is required, the curing period is set in advance, and when the curing period is not required, the above-mentioned laminated coating layer directly becomes the adhesive layer 11. Thereby, the above-mentioned adhesive sheet 1 can be obtained. According to this production example, even when the adhesive layer 11 is thick, it can be stably produced.

As a method of applying the coating liquid of the above-mentioned adhesive composition P, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like can be used. .

(4) Haze value

The haze value (value measured in accordance with JIS K7136:2000) of the pressure-sensitive adhesive layer 11 in the present embodiment is preferably 1.0% or less, more preferably 0.8% or less, and still more preferably 0.6% or less. When the haze value is 1.0% or less, the transparency is extremely high, and it is suitable for optical use. Further, the haze value of the pressure-sensitive adhesive layer 11 is particularly preferably within the above range after the evaluation test of the moist heat whitening resistance to be described later.

(5) Use of adhesive sheets

By using the above-described adhesive sheet 1, for example, the capacitive touch panel 2 shown in Fig. 2 can be manufactured. The touch panel 2 is configured to include a display body module 3; the first film sensor 5a is laminated on the display body module 3 via the adhesive layer 4; and the second film sensor 5b is laminated on the adhesive layer 11 The first film sensor 5a is placed on the second film sensor 5b via the adhesive layer 11.

The adhesive layer 11 in the touch panel 2 is the adhesive layer 11 of the above-mentioned adhesive sheet 1.

Examples of the display body module 3 include a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescence (organic EL) module, and electronic paper.

The adhesive layer 4 can be formed by the adhesive layer 11 of the above-mentioned adhesive sheet 1, or can be formed by other adhesives or adhesive sheets. In the latter case, examples of the adhesive constituting the adhesive layer 4 include a propylene-based adhesive, a rubber-based adhesive, an anthrone-based adhesive, an urethane-based adhesive, a polyester-based adhesive, and a polyethylene. An ether-based adhesive or the like is preferred, and a propylene-based adhesive is preferred.

The first film sensor 5a and the second film sensor 5b in the present embodiment each include a base film 51 and an electrode 52 made of a metal mesh formed on the base film 51. The base film 51 is not particularly limited, and for example, a polyethylene terephthalate film, an acrylic film, a polycarbonate film, or the like can be used.

Examples of the metal constituting the metal mesh of the electrode 52 include copper, silver, and the like, but copper is particularly preferable. According to copper, the resistance value can be reduced to 10 Ω/□ or less, and the touch panel can be enlarged. However, compared with noble metals such as platinum, gold, and silver, copper is more likely to corrode than a transparent conductive material such as tin-doped indium oxide (ITO). However, according to the above-described adhesive layer 11 formed of the adhesive composition P, corrosion of the electrode 52 composed of a copper mesh can be suppressed.

The electrode 52 of the first thin film sensor 5a and the electrode 52 of the second thin film sensor 5b usually form a circuit pattern in the X-axis direction, and the other constitutes a circuit pattern in the Y-axis direction.

In Fig. 2, the electrode 52 of the second thin film sensor 5b in the present embodiment is located above the second thin film sensor 5b. On the other hand, in Figure 2, The electrode 52 of the first thin film sensor 5a is located above the first thin film sensor 5a, but is not limited thereto, and may be located below the first thin film sensor 5a.

The cover material 6 is usually made of a glass plate or a plastic plate. The glass plate is not particularly limited, and examples thereof include chemically strengthened glass, alkali-free glass, quartz glass, soda lime glass, barium-containing glass, yttrium aluminate glass acid, lead glass, borosilicate glass, and barium boron. Tellurite glass, etc. The plastic plate is not particularly limited, and examples thereof include an acrylic plate made of polymethyl methacrylate or the like, a polycarbonate plate, and the like.

In addition, a functional layer such as a hard coat layer, an antireflection layer, or an antiglare layer may be provided on one or both sides of the glass plate or the plastic plate, and an optical component such as a hard coat film, an antireflection film, or an antiglare film may be laminated.

In the present embodiment, the cover material 6 has a step on the surface on the side of the adhesive layer 11, and specifically has a step formed by the presence or absence of the printed layer 7. The printed layer 7 is generally formed in a frame shape on the side of the adhesive layer 11 in the cover material 6.

The material constituting the printing layer 7 is not particularly limited, and a known material for printing can be used. The thickness of the printed layer 7, that is, the step height of 3 to 45 μm is preferable, 5 to 35 μm is more preferable, 7 to 25 μm is particularly preferable, and 7 to 15 μm is further preferable.

Further, the thickness (the height of the step) of the printed layer 7 is preferably from 3 to 30% of the thickness of the adhesive layer 11, particularly preferably from 3.2 to 20%, and further preferably from 3.5 to 15%. Thereby, the adhesive layer 11 easily follows the step generated by the printed layer 7, and it is possible to suppress the occurrence of warpage, bubbles, and the like in the vicinity of the step.

Hereinafter, an example of the method of manufacturing the touch panel 2 described above is performed. Description.

As the adhesive sheet 1, the first adhesive sheet 1 and the second adhesive sheet 1 are prepared. One release sheet 12a is peeled off from the first adhesive sheet 1, and the exposed adhesive layer 11 (first adhesive layer 11) is brought into contact with the electrode 52 of the second thin film sensor 5b and the second thin film sensor. 5b fits. Then, one release sheet 12a is peeled off from the second adhesive sheet 1, and the exposed adhesive layer 11 (second adhesive layer) is in contact with the electrode 52 of the first thin film sensor 5a and the first thin film is sensed. The device 5a is attached.

Further, the other of the second adhesive sheets 12b is peeled off so that the exposed second adhesive layer 11 and the second thin film sensor 5b are opposite to the side on which the first adhesive layer 11 is laminated. The surface (the exposed surface of the base film 51 of the second film sensor 5b) is in contact with each other. Thereby, a laminate in which the release sheet 12b, the first adhesive layer 11, the second thin film sensor 5b, the second adhesive layer 11, and the first thin film sensor 5a are laminated in this order is obtained.

Then, the adhesive layer 4 provided on the release sheet is bonded to the surface of the laminated body on the side of the first thin film sensor 5a (the exposed surface of the base film 51 of the first thin film sensor 5a). Then, the release sheet 12b is peeled off from the laminated body, and the exposed cover material 6 is bonded to the exposed first adhesive layer 11 so that the printed layer 7 side of the cover material 6 comes into contact with the adhesive layer 11. Thereby, the cover material 6, the first adhesive layer 11, the second thin film sensor 5b, the second adhesive layer 11, the first thin film sensor 5a, the adhesive layer 4, and the release sheet are sequentially laminated. Composition.

Finally, the release sheet is peeled off from the above-mentioned constituent body, and the exposed adhesive layer 4 is brought into contact with the display module 3 to bond the constituent body to the display module 3. Thereby, the touch panel 2 shown in FIG. 2 can be manufactured.

After the touch panel 2 is placed under conditions of high temperature and high humidity (for example, at 85 ° C and 85% RH for 240 hours), the adhesive layer 11 (first adhesive layer 11 and second) is returned to normal temperature and normal humidity. The heat-resistant whitening resistance of the adhesive layer 11) is still excellent, so whitening is suppressed. Specifically, the haze value of the adhesive layer 11 can be maintained at 1.0% or less.

The embodiments described above are described in order to facilitate the understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design changes or equivalents falling within the technical scope of the invention.

For example, either one of the release sheets 12a and 12b in the adhesive sheet 1 may be omitted.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples, but the scope of the present invention is not limited to the examples and the like.

[Example 1]

1. Preparation of (meth) acrylate copolymer

60 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of methyl methacrylate, and 20 parts by mass of 2-hydroxyethyl acrylate were copolymerized to prepare a (meth) acrylate polymer (A). The molecular weight of the (meth) acrylate polymer (A) was measured by the method described later, and the weight average molecular weight (Mw) was 600,000.

2. Preparation of adhesive composition

100 parts by mass of the (meth) acrylate polymer (A) obtained in the above process (1) (converted solid content; the same applies hereinafter) as a benzotriazole system 1H-benzotriazole (manufactured by JOHOKU CHEMICAL CO., LTD., product name "BT-120") of rust agent (B) 0.3 parts by mass, trimethylolpropane modified toluene as crosslinking agent (C) Isocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., product name "CORONATE L") 0.15 parts by mass, and 3-glycidyloxypropyltrimethoxydecane as a decane coupling agent (Shin-Etsu Chemical Co., Ltd.) The product name "KBM-403") was 0.2 parts by mass and stirred well, and diluted with methyl ethyl ketone, thereby obtaining a coating solution of an adhesive composition having a solid content concentration of 25% by mass.

Here, the adhesion of the adhesive composition is shown in Table 1. In addition, the details of the outlines and the like described in Table 1 are as follows.

[(Meth)acrylate polymer (A)]

EHA: 2-ethylhexyl acrylate

MMA: Methyl methacrylate

HEA: 2-hydroxyethyl acrylate

BA: n-butyl acrylate

[Benzotriazole-based rust inhibitor (B)]

Rust inhibitor B1:1H-benzotriazole (manufactured by JOHOKU CHEMICAL CO., LTD, product name "BT-120")

Rust inhibitor B2: 1H-tolyltriazole (manufactured by SHIPRO KASEI KAISHA.LTD., product name "SEETEC TT-R")

Rust inhibitor B3: 1-[N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole (manufactured by JOHOKU CHEMICAL CO., LTD, product name "BT-LX")

Rust inhibitor B4: 1-[N,N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole (manufactured by JOHOKU CHEMICAL CO., LTD, product name "TT-LX")

3. Adhesive sheet manufacturing

The coating solution of the obtained adhesive composition was applied to the polyethylene terephthalate film with an anthrone-based release agent by a knife coater so that the thickness after drying became 50 μm. The peeling-treated surface of the heavy release type release sheet (manufactured by Lintec Corporation, product name "SP-PET382150" thickness: 38 μm) which was subjected to the release treatment was heat-treated at 90 ° C for 1 minute to form a coating layer.

A peeling-treated surface of a light-peelable release sheet (manufactured by LINTEC Corporation, product name "SP-PET382120", thickness: 38 μm) which was subjected to a release treatment of one side of a polyethylene terephthalate film with an oxime-based release agent The light release type release sheet is bonded to the coating layer in such a manner that the coating layer is in contact with each other. Thereafter, the film was cured for 7 days under conditions of 23° C. and 50% RH to produce an adhesive sheet comprising a heavy release release sheet/adhesive layer (thickness: 50 μm)/light release release sheet.

[Examples 2 to 5, Comparative Examples 1 and 2]

The types and ratios of the respective monomers constituting the (meth) acrylate polymer (A), the weight average molecular weight (Mw) of the (meth) acrylate polymer (A), and the benzoic acid were changed as shown in Table 1. An adhesive sheet was produced in the same manner as in Example 1 except that the type of the triazole-based rust preventive (B) was used.

Here, the 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 (passed in the following order): manufactured by Tosoh Corporation

TSK guard column HXL-H

TSK gel GMHXL (×2)

TSK gel G2000HXL

‧ Determination of solvent: tetrahydrofuran

‧Measurement temperature: 40 ° C

[Test Example 1] (Evaluation of resistance to wet heat whitening)

The adhesive layer of the adhesive sheets obtained in the examples and the comparative examples was sandwiched between two sheets of alkali-free glass (thickness: 1 mm) of 70 mm × 70 mm size, and the laminate was subjected to 30 minutes at 50 ° C and 0.5 MPa. Autoclave treatment, this was taken as a sample.

The obtained sample was stored under humid heat conditions of 85 ° C and 85% RH for 240 hours. Thereafter, the atmosphere was returned to an atmosphere of 23 ° C and 50% RH (normal temperature and normal humidity), and the haze value of the adhesive layer was measured. After the haze value was restored to the above-mentioned normal temperature and normal humidity atmosphere, the sample was subjected to a haze meter (manufactured by NIPPON DENSHOKU INDUSTRIES Co., Ltd., product name "NDH-5000") within 30 minutes in accordance with JIS K7136:2000. Determination. According to the measured haze value, the wet heat whitening resistance was evaluated by the following criteria. The results are shown in Table 1.

○: The haze value is 1.0% or less

×: haze value exceeds 1.0%

[Test Example 2] (corrosion inhibition evaluation)

(1) Fabrication of copper mesh laminate film

A polyethylene terephthalate (PET) film (manufactured by TOYOBO CO., LTD., product name "PET100A4100", thickness: 100 μm) was prepared, and blackening was performed on one side. Copper foil (manufactured by Furukawa Circuit Foil Co., Ltd., product name "BW-S", thickness: 10 μm), and polyurethane-based adhesive (Takeda Pharmaceutical Company Limited., TAKELAC A310/TAKENATE A10/ethyl acetate) =12/1/21 (mass ratio)).

The surface of the copper foil opposite to the blackened surface and the PET film were bonded together using the urethane-based adhesive to obtain a laminate comprising a PET film/adhesive layer/copper foil.

Casein was applied to the copper foil side (blackened surface) of the obtained laminate, and dried to prepare a photosensitive resin layer. Then, the photosensitive resin layer was subjected to ultraviolet light intimate exposure through a mask having a pattern, and developed with water. As the mask, a pattern having a line width of 10 μm and a pitch of 300 μm was used. Next, after hardening treatment, baking was performed at 100 ° C to form a resist pattern.

The layered body on which the resist pattern was formed was sprayed with a ferric chloride solution (Beauzer: 42, temperature: 30 ° C) from the resist pattern side, and etched, and washed with water. Next, after the resist pattern is peeled off using an alkaline solution, washing and drying treatment are performed. In this way, a copper mesh laminate film composed of a PET film/adhesive layer/copper mesh was obtained.

(2) Corrosion inhibition evaluation

The light release sheet was peeled off from the adhesive sheets obtained in the examples and the comparative examples, and the exposed adhesive layer was attached to the copper mesh side of the copper mesh laminate film. Thereafter, the heavy release type release sheet was peeled off from the adhesive layer, and a PET film (product name "PET A4100", thickness: 100 μm) manufactured by TOYOBO CO., LTD. was attached to the exposed adhesive layer to obtain a PET film/ Subsequent layer/copper mesh/adhesive layer/PET film The laminated body was constructed and used as a sample.

Store the above samples under humid heat conditions of 85 ° C and 85% RH 250 hours. Thereafter, the presence or absence of corrosion of the copper mesh was visually confirmed, and the performance of corrosion inhibition was evaluated by the following criteria. The results are shown in Table 1.

○: Copper mesh is not corroded

×: corrosion of copper mesh

[Test Example 3] (calculation of dielectric constant)

An adhesive layer having a thickness of 100 μm was formed on one surface of a polyethylene terephthalate film having a thickness of 50 μm in the same manner as in the examples and the comparative examples, and a polyethylene terephthalate having a thickness of 50 μm was attached to the adhesive layer. After the ester film, it was cut to 50 mm x 50 mm. The capacitance (C1) of the obtained laminate was measured using an impedance analyzer ("HP-4194A" manufactured by Japan Hewlett-Packard Company). Further, two sheets of the above-mentioned polyethylene terephthalate film having a thickness of 50 μm were stacked and cut into 50 mm × 50 mm, and the electrostatic capacitance (C2) was measured in the same manner. Further, the electrostatic capacitance (C3) of the adhesive is calculated by subtracting C2 from C1. According to the electrostatic capacitance C3, the dielectric constant ε _{s of the} adhesive is calculated according to the following formula. The results are shown in Table 1.

ε _s =(C3×d)/(ε ₀ ×S)

ε _s : dielectric constant of the adhesive

ε ₀ : dielectric constant of vacuum (8.854×10 ^-12 )

C3: electrostatic capacitance of the adhesive

S: area of the adhesive layer

d: thickness of the adhesive layer

From the above results, it was evaluated that the dielectric constant ε _s of the adhesive layer was 2.0 to 8.0 was good (○), and those exceeding 8.0 were evaluated as poor (×). The evaluation results are also shown in Table 1.

As is clear from Table 1, the pressure-sensitive adhesive sheets obtained in the examples were excellent in moisture-heat-whitening resistance and corrosion-inhibiting effect, and the dielectric constant was also sufficiently low, which was good.

[Industrial availability]

The adhesive composition, the adhesive, and the adhesive sheet of the present invention can be suitably used, for example, in a capacitive touch panel using a copper mesh as an electrode.

1‧‧‧Adhesive film

11‧‧‧Adhesive layer

12a, 12b‧‧‧ peeling film

Claims (9)

An adhesive composition for forming an adhesive for use in contact with a metal member, characterized by comprising: a (meth) acrylate polymer (A) as a monomer unit constituting the polymer, containing more than 15 masses % and 30% by mass or less of a monomer having a hydroxyl group, which does not contain a monomer having a carboxyl group; and a benzotriazole-based rust inhibitor (B). The adhesive composition according to claim 1, wherein the benzotriazole-based rust inhibitor (B) contains a compound selected from the group consisting of 1H-benzotriazole, 1H-tolyltriazole, and 1- At least one of [N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole and 1-[N,N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole 1 species. The adhesive composition according to claim 1, wherein the (meth) acrylate polymer (A) contains a glass transition as a homopolymer as a monomer unit constituting the polymer. A hard monomer having a temperature of 70 ° C or higher. The adhesive composition according to claim 1, wherein the (meth) acrylate polymer (A) contains 2-(meth)acrylic acid as a monomer unit constituting the polymer. Hexyl hexyl ester. The adhesive composition according to claim 1, wherein the adhesive composition further contains a crosslinking agent (C). An adhesive characterized in that the adhesive is obtained by crosslinking an adhesive composition according to any one of claims 1 to 5. The adhesive according to claim 6, wherein the dielectric constant at 1.0 MHz is 2.0 to 8.0. An adhesive sheet comprising: two release sheets; and an adhesive layer sandwiched by the release sheet in contact with the release faces of the two release sheets, wherein the adhesive layer is in the scope of claim 6 The adhesive composition described in the item. The adhesive sheet according to claim 8, wherein the adhesive layer is disposed on the touch panel in contact with the metal mesh.