KR20220140648A - Adhesive composition, adhesive agent, and adhesive sheet - Google Patents

Abstract

A pressure-sensitive adhesive composition for constituting a pressure-sensitive adhesive used in contact with a metal member, containing more than 15% by mass and 30% by mass or less of a monomer having a hydroxyl group as a monomer unit constituting a polymer, and not containing a monomer having a carboxyl group (meth) A pressure-sensitive adhesive composition comprising an acrylic acid ester polymer (A) and a benzotriazole-based rust inhibitor (B). According to such an adhesive composition, corrosion of the metal member in contact can be suppressed and it is excellent also in moist-heat-resistance whitening property.

Description

An adhesive composition, an adhesive, and an adhesive sheet {ADHESIVE COMPOSITION, ADHESIVE AGENT, AND ADHESIVE SHEET}

The present invention relates to a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet used in contact with a metal member, particularly a metal mesh of a touch panel, and a pressure-sensitive adhesive composition for constituting the pressure-sensitive adhesive.

DESCRIPTION OF RELATED ART In various mobile electronic devices, such as a smart phone and a tablet terminal in recent years, a touch panel is used more often as a display. As a touch panel method, there are a resistive film method, a capacitive method, and the like, but in the above mobile electronic devices, the capacitive method is mainly employed.

Many of the electrodes used for small touch panels, such as a smart phone, are comprised with the transparent conductive film which consists of tin-doped indium oxide (ITO). However, since it is difficult for ITO to lower|hang a resistance value to 10 ohms/square or less, when ITO is used for a large-sized electrode pattern, signal deterioration generate|occur|produces, Therefore, it was difficult to enlarge a touch panel.

Then, copper which can lower a resistance value to 10 ohms/square or less attracts attention as an electrode material of a touch panel, and various copper electrodes are examined. However, since copper is easy to corrode compared with ITO, when the adhesive used for an ITO electrode is used for a copper electrode as it is, a copper electrode will corrode. Therefore, there is a need for a pressure-sensitive adhesive that does not corrode the copper electrode.

By the way, the touch panel may be subjected to high temperature, high humidity conditions, and it is necessary to have durability that can be used without any problem even through such conditions. However, in the conventional touchscreen, when returning to normal temperature and humidity after high-temperature, high-humidity conditions, the problem that an adhesive layer whitens (wet-heat whitening) tends to generate|occur|produce.

In Patent Document 1, as an adhesive to be affixed to the electromagnetic wave shielding film, a near-infrared absorbing dye is added to impart a near-infrared absorbing action, and a benzotriazole compound is added to prevent deterioration of the near-infrared absorbing dye. A pressure-sensitive adhesive is disclosed.

Japanese Patent No. 4818236

However, the adhesive of patent document 1 is for optical filters of a plasma display panel, and this adhesive cannot be applied to the touch panel from which a use differs. For example, when the said adhesive is applied to a touchscreen, the problem of the wet-heat whitening mentioned above will arise.

The present invention has been made in view of the actual conditions described above, and an object of the present invention is to provide a pressure-sensitive adhesive composition, pressure-sensitive adhesive, and pressure-sensitive adhesive sheet that can suppress corrosion of a contacting metal member and are also excellent in heat-and-moisture whitening resistance.

In order to achieve the above object, firstly, the present invention is a pressure-sensitive adhesive composition for constituting a pressure-sensitive adhesive used in contact with a metal member, wherein the amount of a monomer having a hydroxyl group as a monomer unit constituting the polymer is more than 15% by mass and not more than 30% by mass. A (meth)acrylic acid ester polymer (A) that contains and does not contain a monomer having a carboxyl group, and a benzotriazole-based rust preventive agent (B) are provided (Invention 1).

When the (meth)acrylic acid ester polymer (A) in the pressure-sensitive adhesive composition according to the invention (invention 1) contains a hydroxyl group-containing monomer in the above amount as a monomer unit constituting the polymer, the pressure-sensitive adhesive obtained has heat-and-moisture whitening resistance. it becomes excellent On the other hand, when hydrophilic groups, such as a hydroxyl group, exist in a predetermined amount of an adhesive as mentioned above, an adhesive will become easy to absorb water, and it will become easy to corrode the metal member which contacts the said adhesive. However, the adhesive composition which concerns on the said invention (invention 1) can suppress corrosion of the metal member contacting by containing a benzotriazole-type rust preventive agent (B). Moreover, since the (meth)acrylic acid ester polymer (A) in the said adhesive composition (invention 1) does not contain a carboxyl group containing monomer, corrosion of the metal member by a carboxyl group (acid) can also be prevented.

In the invention (invention 1), 1H-benzotriazole, 1H-tolyltriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole as the benzotriazole-based rust inhibitor (B) And it is preferable to contain at least 1 sort(s) selected from the group which consists of 1-[N,N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole (Invention 2).

In the above inventions (Inventions 1 and 2), the (meth)acrylic acid ester polymer (A) preferably contains a hard monomer having a glass transition temperature of 70° C. or higher as a homopolymer as a monomer unit constituting the polymer ( Invention 3).

In the said inventions (Inventions 1-3), it is preferable that the said (meth)acrylic acid ester polymer (A) contains 2-ethylhexyl (meth)acrylic acid as a monomer unit which comprises the said polymer (Invention 4).

In the said invention (invention 1-4), it is preferable that the said adhesive composition further contains a crosslinking agent (C) (invention 5).

Second, the present invention provides a pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition (Inventions 1 to 5) (Invention 6).

In the said invention (invention 6), it is preferable that the dielectric constant in 1.0 MHz is 2.0-8.0 (invention 7).

Thirdly, the present invention includes two release sheets and a pressure-sensitive adhesive layer sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets, wherein the pressure-sensitive adhesive layer is made of the pressure-sensitive adhesive (Inventions 6 and 7) It provides an adhesive sheet, characterized in that (Invention 8).

In the said invention (invention 8), it is preferable that the said adhesive layer is arrange|positioned so that it may contact with the metal mesh in a touch panel (invention 9).

ADVANTAGE OF THE INVENTION According to the adhesive composition which concerns on this invention, an adhesive, and an adhesive sheet, corrosion of the metal member which contacts can be suppressed and it is excellent also in moist-heat resistance whitening property.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing of the adhesive sheet which concerns on one Embodiment of this invention.
2 is a cross-sectional view showing an example of the configuration of a touch panel.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described.

[Adhesive composition]

The adhesive composition (henceforth "adhesive composition P") which concerns on this embodiment is an adhesive composition for comprising the adhesive used in contact with a metal member. As a metal member, Preferably, although the copper mesh as an electrode in a capacitive touch panel is illustrated, it is not limited to this.

The adhesive composition P contains more than 15 mass % and 30 mass % or less of a monomer having a hydroxyl group (hydroxyl group-containing monomer) as a monomer unit constituting the polymer, and (meth)acrylic acid which does not contain a monomer having a carboxyl group (carboxyl group-containing monomer) The ester polymer (A) and the benzotriazole-based rust preventive agent (B) are contained, and preferably a crosslinking agent (C) is further contained. In addition, in this specification, (meth)acrylic acid ester means both an acrylic acid ester and a methacrylic acid ester. Other similar terms are the same. In addition, the concept of "copolymer" shall also be included in "polymer".

When the (meth)acrylic acid ester polymer (A) in the pressure-sensitive adhesive composition P contains a hydroxyl group-containing monomer in the above amount as a monomer unit constituting the polymer, the pressure-sensitive adhesive obtained under high-temperature, high-humidity conditions (eg, 85°C) , 240 hours) under the conditions of 85%RH, whitening at the time of returning to normal temperature and normal humidity is suppressed, ie, it becomes the thing excellent in moist-heat-resistance whitening property. When (meth)acrylic acid ester polymer (A) contains a hydroxyl-containing monomer in the said quantity as a monomer unit, a predetermined amount of hydroxyl groups will remain in the adhesive obtained. The hydroxyl group is a hydrophilic group, and when such a hydrophilic group is present in a predetermined amount of the pressure-sensitive adhesive, even when the pressure-sensitive adhesive is placed under high-temperature, high-humidity conditions, compatibility with moisture that has penetrated into the pressure-sensitive adhesive under the high-temperature, high-humidity conditions is good, and as a result, whitening of the pressure-sensitive adhesive is suppressed will become

However, when a hydrophilic group exists in a predetermined amount of an adhesive as mentioned above, an adhesive will become easy to absorb water, and it will become easy to corrode the metal member which contacts the said adhesive. However, by containing the benzotriazole-type rust preventive agent (B), the adhesive composition P which concerns on this embodiment can suppress that the metal member in contact is corroded.

In addition, although the reactivity of the crosslinking agent (C) and (meth)acrylic acid ester polymer (A) mentioned later tends to fall by the presence of a benzotriazole-type rust preventive agent (B), (meth)acrylic acid ester polymer (A) is a monomer When the hydroxyl group-containing monomer is contained in the above amount as a unit, the reaction between the crosslinking agent (C) and the (meth)acrylic acid ester polymer (A) proceeds favorably.

On the other hand, since the (meth)acrylic acid ester polymer (A) in the said adhesive composition P does not contain a carboxyl group containing monomer, corrosion of the metal member by a carboxyl group (acid) can also be prevented.

(1) (meth)acrylic acid ester polymer (A)

As a hydroxyl-containing monomer which (meth)acrylic acid ester polymer (A) contains as a monomer unit which comprises the said polymer, for example, (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 2-hydroxypropyl, ( (meth)acrylic acid hydroxyalkyl esters such as 3-hydroxypropyl (meth)acrylic acid, 2-hydroxybutyl (meth)acrylic acid, 3-hydroxybutyl (meth)acrylic acid, and 4-hydroxybutyl (meth)acrylic acid can be heard Among these, 2-hydroxyethyl (meth)acrylic acid is preferable from the point of reactivity of the hydroxyl group with the crosslinking agent (C) in the obtained (meth)acrylic acid ester polymer (A), and copolymerizability with another monomer. These may be used independently and may be used in combination of 2 or more type.

As mentioned above, the (meth)acrylic acid ester polymer (A) contains more than 15 mass % and 30 mass % or less of a hydroxyl-containing monomer as a monomer unit which comprises the said polymer. When content of the hydroxyl-containing monomer as a monomer unit in a (meth)acrylic acid ester polymer (A) is 15 mass % or less, an adhesive layer will be inferior to moist-and-heat whitening resistance. On the other hand, when content of a hydroxyl-containing monomer exceeds 30 mass %, even if it contains a benzotriazole-type rust preventive agent (B), the moisture content absorbed by an adhesive will increase too much, and it will become easy to corrode a metal member.

From such a viewpoint, it is preferable that the (meth)acrylic acid ester polymer (A) contains 16-25 mass % of a hydroxyl-containing monomer as a monomer unit which comprises the said polymer, and it is especially preferable to contain 18-20 mass %.

The (meth)acrylic acid ester polymer (A) does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer. Here, "does not contain a monomer having a carboxyl group" means substantially not containing a monomer having a carboxyl group, and in addition to not containing a carboxyl group-containing monomer at all, corrosion of the metal member by a carboxyl group does not occur. It is allowed to contain a carboxyl group-containing monomer. Specifically, in the (meth)acrylic acid ester polymer (A), 0.1 mass% or less of a carboxyl group-containing monomer as a monomer unit is allowed to be contained in an amount of preferably 0.01 mass% or less.

The (meth)acrylic acid ester polymer (A) preferably contains (meth)acrylic acid alkylester having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer. Thereby, the adhesive obtained can express preferable adhesiveness. In addition, the hard monomer mentioned later is excluded from the said (meth)acrylic-acid alkylester.

Examples of the (meth)acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include methyl acrylate, (meth)ethyl acrylate, (meth)acrylic acid propyl, (meth)acrylate n-butyl, (meth)acrylic acid n-pentyl, (meth)acrylic acid n-hexyl, (meth)acrylic acid 2-ethylhexyl, (meth)acrylic acid isooctyl, (meth)acrylic acid n-decyl, (meth)acrylic acid n-dodecyl, (meth)acrylic acid myristyl, (meth)acrylic acid ) palmityl acrylate, stearyl (meth)acrylate, and the like. Among them, (meth)acrylic acid ester having 1 to 8 carbon atoms in the alkyl group is preferable from the viewpoint of further improving the adhesiveness, and n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are particularly preferable, ( More preferred is 2-ethylhexyl meth)acrylic acid. According to 2-ethylhexyl (meth)acrylic acid, the dielectric constant of the adhesive obtained can be made low, and the malfunction of a touchscreen can be suppressed. In addition, these may be used independently and may be used in combination of 2 or more type.

It is preferable that the (meth)acrylic acid ester polymer (A) contains 30-85 mass % of C1-C20 (meth)acrylic acid alkylester of an alkyl group as a monomer unit which comprises the said polymer, especially 40-75 mass It is preferable to contain %, Furthermore, it is preferable to contain 50-65 mass %.

Moreover, it is preferable that the glass transition temperature (Tg) as a homopolymer contains the hard monomer 70 degreeC or more of (meth)acrylic acid ester polymer (A) as a monomer unit which comprises the said polymer. By containing the said hard monomer as a monomer unit which comprises a (meth)acrylic acid ester polymer (A), the adhesive obtained improves cohesive force and becomes a thing excellent in durability. In particular, when 2-ethylhexyl (meth)acrylic acid is used as the monomer unit constituting the (meth)acrylic acid ester polymer (A), the cohesive force tends to decrease, so it is preferable to use the hard monomer. It is preferable that it is 75-200 degreeC, and, as for the glass transition temperature (Tg) of the homopolymer of the said hard monomer, it is especially preferable that it is 80-180 degreeC.

Examples of the hard monomer include methyl methacrylate (Tg 105° C.), isobornyl acrylate (Tg 94° C.), isobornyl methacrylate (Tg 180° C.), and acryloylmorpholine (Tg 145° C.) , adamantyl acrylate (Tg 115°C), adamantyl methacrylate (Tg 141°C), dimethyl acrylamide (Tg 89°C), and acrylamide (Tg 165°C). These may be used independently and may be used in combination of 2 or more type.

Among the hard monomers, methyl methacrylate, isobornyl acrylate, and acryloylmorpholine are more preferable from the viewpoint of more exhibiting the performance of the hard monomer while preventing adverse effects on other properties such as tackiness and transparency, and methacrylic acid Methyl acid is particularly preferred.

It is preferable to contain 10-45 mass % of the said hard monomer as a monomer unit which comprises the said polymer, and, as for (meth)acrylic acid ester polymer (A), it is especially preferable to contain 15-30 mass %. By containing the said hard monomer 10 mass % or more, the improvement effect of the durability by the said monomer unit is expectable. On the other hand, by making the said hard monomer into content of 45 mass % or less, the relative shortage of the monomer unit other than that in the (meth)acrylic acid ester polymer (A) is prevented, and it is excellent in the adhesiveness of the adhesive obtained and heat-and-moisture whitening resistance. can be done as

The (meth)acrylic acid ester polymer (A) may contain another monomer as a monomer unit constituting the polymer as desired. As another monomer, also in order not to interfere with the action of a hydroxyl-containing monomer, the monomer which does not contain the functional group which has reactivity is preferable. Examples of such other monomers include (meth)acrylic acid alkoxyalkyl esters such as (meth)acrylic acid methoxyethyl and (meth)acrylic acid ethoxyethyl, and (meth)acrylic acid esters having an aliphatic ring such as (meth)acrylic acid cyclohexyl. and (meth)acrylic acid esters having non-crosslinkable tertiary amino groups such as (meth)acrylic acid N,N-dimethylaminoethyl and (meth)acrylic acid N,N-dimethylaminopropyl, vinyl acetate, and styrene. These may be used independently and may be used in combination of 2 or more type.

A random copolymer may be sufficient as the polymerization aspect of a (meth)acrylic acid ester polymer (A), and a block copolymer may be sufficient as it.

The weight average molecular weights of the (meth)acrylic acid ester polymer (A) are 300,000 to 1,000,000, preferably 400,000 to 900,000, and particularly preferably 500,000 to 700,000. In addition, the weight average molecular weight in this specification is the value of polystyrene conversion measured by the gel permeation chromatography (GPC) method.

When the weight average molecular weight of the (meth)acrylic acid ester polymer (A), which is the main adhesive of the pressure-sensitive adhesive composition P, is 300,000 or more, the durability of the obtained pressure-sensitive adhesive is improved, and the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is 1 million By being below, the coatability of the adhesive composition P becomes favorable.

In addition, in the adhesive composition P, the (meth)acrylic acid ester polymer (A) may be used individually by 1 type, and may be used in combination of 2 or more type.

(2) Benzotriazole-based rust inhibitor (B)

Examples of the benzotriazole-based rust inhibitor (B) include 1H-benzotriazole, 1H-tolyltriazole, 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, etc. can be heard Among them, 1H-benzotriazole, 1H-tolyltriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole and 1-[N,N-bis(2-ethylhexyl) Aminomethyl]methylbenzotriazole is preferred. According to these, corrosion of the metal member in contact can be suppressed especially effectively. The said benzotriazole-type rust preventive agent (B) may be used independently and may be used in combination of 2 or more type.

The content of the benzotriazole-based rust preventive agent (B) in the pressure-sensitive adhesive composition P is preferably 0.01 to 2.0 parts by mass, particularly preferably 0.05 to 1.0 parts by mass, with respect to 100 parts by mass of the (meth)acrylic acid ester polymer (A), Furthermore, it is preferable that it is 0.1-0.5 mass part. When content of a benzotriazole-type rust preventive agent (B) is 0.01 mass part or more, the corrosion inhibitory effect of a metal member is fully acquired. Moreover, adhesiveness will not have a bad influence as content of a benzotriazole type rust preventive agent (B) is 2.0 mass parts or less.

(3) crosslinking agent (C)

It is preferable that the adhesive composition P contains a crosslinking agent (C). The adhesive composition P crosslinks the (meth)acrylic acid ester copolymer (A) by containing a crosslinking agent (C), forms a three-dimensional network structure, and improves the cohesive force of the adhesive obtained.

The crosslinking agent (C) may react with a reactive group (hydroxyl group of a hydroxyl group-containing monomer that is a monomer unit) of the (meth)acrylic acid ester copolymer (A), for example, an isocyanate crosslinking agent, an epoxy crosslinking agent, an amine crosslinking agent , a melamine-based crosslinking agent, an aziridine-based crosslinking agent, a hydrazine-based crosslinking agent, an aldehyde-based crosslinking agent, an oxazoline-based crosslinking agent, a metal alkoxide-based crosslinking agent, a metal chelate-based crosslinking agent, a metal salt-based crosslinking agent, and an ammonium salt-based crosslinking agent. Among the above, it is preferable to use the isocyanate type crosslinking agent excellent in the reactivity with the hydroxyl group which the (meth)acrylic acid ester polymer (A) has. In addition, a crosslinking agent (C) can be used individually by 1 type or in combination of 2 or more type.

An isocyanate type crosslinking agent contains a polyisocyanate compound at least. As a polyisocyanate compound, For example, aromatic polyisocyanate, such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, aliphatic polyisocyanate, such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate Adducts which are reactants with low molecular weight active hydrogen-containing compounds such as alicyclic polyisocyanates such as alicyclic polyisocyanates, and their biuret forms, isocyanurate forms, and further, ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil sieve and the like. Especially, from a reactive viewpoint with a hydroxyl group, trimethylol propane modified|denatured aromatic polyisocyanate, especially trimethylol propane modified|denatured tolylene diisocyanate is preferable.

It is preferable that content of the crosslinking agent (C) in the adhesive composition P is 0.001-10 mass parts with respect to 100 mass parts of (meth)acrylic acid ester polymer (A), It is especially preferable that it is 0.01-5 mass parts, Furthermore, it is 0.02 It is preferable that it is -1 mass part.

When content of a crosslinking agent (C) exists in the said range, the cohesive force of the adhesive obtained becomes a preferable thing, and durability of an adhesive improves.

(4) Various additives

To the pressure-sensitive adhesive composition P, if desired, various additives commonly used in acrylic pressure-sensitive adhesives, such as silane coupling agents, antistatic agents, tackifiers, antioxidants, ultraviolet absorbers, light stabilizers, softeners, fillers, refractive index modifiers, etc. may be added. can

In particular, it is preferable that a silane coupling agent is added as an additive to the pressure-sensitive adhesive composition P from the viewpoint of improving durability. As a silane coupling agent, it is an organosilicon compound which has at least 1 alkoxysilyl group in a molecule|numerator, Compatibility with the (meth)acrylic acid ester polymer (A) is preferable. Moreover, when the adhesive sheet 1 is an optical use, the silane coupling agent which has light transmittance is preferable.

As such a silane coupling agent, for example, polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane; 3-glycidoxypropyltrimethoxysilane; Silicon compounds having an epoxy structure such as 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyl Mercapto group-containing silicon compounds such as dimethoxymethylsilane, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3 -Amino group-containing silicon compounds such as aminopropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, or at least one of these, and methyltriethoxysilane, ethyltriethoxysilane and a condensate of an alkyl group-containing silicon compound such as methyltrimethoxysilane and ethyltrimethoxysilane. These may be used individually by 1 type, and may be used in combination of 2 or more type.

It is preferable that it is 0.01-1.0 mass part with respect to 100 mass parts of (meth)acrylic acid ester polymers (A), and, as for the addition amount of a silane coupling agent, it is preferable that it is especially 0.05-0.5 mass part.

(5) Preparation of adhesive composition

The adhesive composition P is a (meth)acrylic acid ester polymer (A) prepared by mixing the obtained (meth)acrylic acid ester polymer (A) and a benzotriazole-based rust preventive agent (B), and optionally a crosslinking agent (C) And it can be prepared by adding an additive.

A (meth)acrylic acid ester polymer (A) can be manufactured by superposing|polymerizing the mixture of the monomer unit which comprises a polymer by the normal radical polymerization method. Superposition|polymerization of the (meth)acrylic acid ester polymer (A) can be performed by the solution polymerization method etc. using a polymerization initiator as needed. As a polymerization solvent, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone etc. are mentioned, for example, You may use 2 or more types together.

As a polymerization initiator, an azo type compound, an organic peroxide, etc. are mentioned, You may use 2 or more types together. As the azo compound, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane1-carbonitrile) ), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'-azo Bis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-hydroxymethylpropionitrile), 2,2'-azo bis[2-(2-imidazolin-2-yl)propane] and the like.

Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl)peroxydicarbonate, t-butylperoxyneodecanoate, t-butylperoxypivalate, (3,5,5-trimethylhexanoyl)peroxide, dipropionylperoxide, diacetylperoxide, etc. are mentioned.

Moreover, the said polymerization process WHEREIN: By mix|blending chain transfer agents, such as 2-mercaptoethanol, the weight average molecular weight of the polymer obtained can be adjusted.

When a (meth)acrylic acid ester polymer (A) is obtained, to the solution of the (meth)acrylic acid ester polymer (A), a benzotriazole-based rust preventive agent (B), and optionally a crosslinking agent (C), an additive and a diluent solvent are added, , by sufficiently mixing to obtain an adhesive composition P (coating solution) diluted with a solvent.

Examples of the diluting solvent include aliphatic hydrocarbons such as hexane, heptane and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, methanol, ethanol, propanol, butanol, 1-methoxy Alcohols such as -2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone, esters such as ethyl acetate and butyl acetate, and cellosolve solvents such as ethyl cellosolve used

The concentration and viscosity of the thus prepared coating solution may be within a range that can be coated, and is not particularly limited, and may be appropriately selected depending on the situation. For example, it is diluted so that the density|concentration of the adhesive composition P may become 10-40 mass %. In addition, when obtaining a coating solution, addition of a diluent solvent etc. is not a necessary condition, and it is not necessary to add a diluent solvent as long as the adhesive composition P has a coatable viscosity, etc. In this case, the adhesive composition P turns into a coating solution which uses the polymerization solvent of the (meth)acrylic acid ester polymer (A) as a dilution solvent as it is.

〔adhesive〕

The pressure-sensitive adhesive according to the present embodiment is obtained by crosslinking the pressure-sensitive adhesive composition P. Crosslinking of the adhesive composition P can be performed by heat treatment. In addition, this heat treatment can also serve as a drying process at the time of volatilizing the dilution solvent etc. of the adhesive composition P.

When heat-processing, it is preferable that the heating temperature is 50-150 degreeC, and it is especially preferable that it is 70-120 degreeC. Moreover, it is preferable that they are 30 second - 10 minutes, and, as for a heating time, it is especially preferable that they are 50 seconds - 2 minutes. After the heat treatment, if necessary, a curing period of about 1 to 2 weeks may be set at normal temperature (eg, 23°C, 50%RH). A pressure-sensitive adhesive layer is formed after the lapse of the curing period when this curing period is required, and after the end of the heat treatment when the curing period is unnecessary.

The pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition P can suppress corrosion of the metal member in contact with the benzotriazole-based rust preventive agent (B), and the (meth)acrylic acid ester polymer (A) has a hydroxyl group It exhibits excellent heat-and-moisture whitening resistance.

It is preferable that the dielectric constant in 1.0 MHz of the adhesive which concerns on this embodiment is 2.0-8.0, It is especially preferable that it is 2.0-7.0, Furthermore, it is preferable that it is 2.0-6.0. When the dielectric constant of an adhesive is 2.0-8.0, the malfunction of the touch panel resulting from an adhesive can be suppressed effectively. In addition, the dielectric constant measuring method of an adhesive is as showing in the test example mentioned later.

[adhesive sheet]

As shown in FIG. 1, the adhesive sheet 1 which concerns on this embodiment is peeling of 2 sheets 12a, 12b, so that the peeling surface of these 2 sheets may be in contact with the peeling sheet 12a, 12b. It is composed of an adhesive layer 11 sandwiched between sheets 12a and 12b. However, in the adhesive sheet 1, the peeling sheets 12a, 12b are not essential components, and peeling and removing at the time of use of the adhesive sheet 1 are carried out. In addition, the peeling surface of the peeling sheet in this specification means the surface which has peelability in a peeling sheet, and it includes both the surface to which the peeling process was performed, and the surface which shows peelability even if it does not perform a peeling process.

(1) adhesive layer

The adhesive layer 11 is comprised from the adhesive formed by bridge|crosslinking the adhesive composition P mentioned above. It is preferable that the thickness (value measured according to JISK7130) of the adhesive layer 11 is 10-300 micrometers, It is especially preferable that it is 25-250 micrometers, Furthermore, it is preferable that it is 50-100 micrometers. When the thickness of the adhesive layer 11 is 10 micrometers or more, the outstanding adhesive force is fully exhibited, and when the thickness of the adhesive layer 11 is 300 micrometers or less, workability becomes favorable. Moreover, if the thickness of the adhesive layer 11 is 25-100 micrometers, it will become preferable as an optical use, especially a touchscreen use. In addition, the adhesive layer 11 may be formed in a single layer, and may be formed by laminating|stacking multiple layers.

(2) release sheet

It does not specifically limit as release sheet 12a, 12b, A well-known plastic film can be used. For example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate Film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene/(meth)acrylic acid copolymer film, ethylene/(meth)acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film or the like is used. Moreover, these crosslinked films are also used. Moreover, these laminated|multilayer films may be sufficient.

It is preferable that the peeling process is given to the peeling surface (particularly, the surface in contact with the adhesive layer 11) of the said peeling sheet 12a, 12b. As a release agent used for a peeling process, the release agent of an alkyd type, a silicone type, a fluorine type, an unsaturated polyester type, a polyolefin type, and a wax type is mentioned, for example. In addition, among the release sheets 12a and 12b, one release sheet is set as a heavy release type release sheet with a large peeling force, and the other release sheet is a light release type release sheet with a small peel force. It is preferable to

Although there is no restriction|limiting in particular about the thickness of peeling sheet 12a, 12b, Usually, it is about 20-150 micrometers.

(3) Manufacture of adhesive sheet

As a single manufacturing example of the adhesive sheet 1, the coating liquid of the said adhesive composition P is apply|coated to the peeling surface of one peeling sheet 12a (or 12b), heat-processing is performed, the adhesive composition P is crosslinked, and an application layer After forming, the release surface of the other release sheet 12b (or 12a) is superimposed on the application layer. By providing a curing period when a curing period is required, when a curing period is unnecessary, the said application layer becomes the adhesive layer 11 as it is. Thereby, the said adhesive sheet 1 is obtained. The conditions of heat treatment and curing are as described above.

As another manufacturing example of the adhesive sheet 1, the coating liquid of the said adhesive composition P is apply|coated to the peeling surface of one peeling sheet 12a, heat-processing is performed, the adhesive composition P is crosslinked, and an application layer is formed, A release sheet 12a with an application layer is obtained. Moreover, the coating liquid of the said adhesive composition P is apply|coated to the peeling surface of the other peeling sheet 12b, heat-processing is performed, the adhesive composition P is crosslinked, an application layer is formed, and the peeling sheet 12b with an application layer is formed. get And the release sheet 12a with an application layer and the release sheet 12b with an application layer are bonded together so that both application layers may mutually contact. When a curing period is required, by providing a curing period, when a curing period is unnecessary, the laminated application layer becomes the pressure-sensitive adhesive layer 11 as it is. Thereby, the said adhesive sheet 1 is obtained. According to this manufacturing example, even when the adhesive layer 11 is thick, it becomes possible to manufacture stably.

As a method of applying the coating liquid of the 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

It is preferable that haze value (value measured according to JIS K7136:2000) of the adhesive layer 11 in this embodiment is 1.0 % or less, It is especially preferable that it is 0.8 % or less, Furthermore, it is preferable that it is 0.6 % or less. do. Transparency is very high that a haze value is 1.0 % or less, and it becomes a thing suitable as an optical use. Moreover, it is especially preferable that the haze value of the adhesive layer 11 exists in the said range also after the evaluation test of the heat-and-moisture whitening resistance mentioned later.

(5) Use of adhesive sheet

By using the said adhesive sheet 1, the capacitive touch panel 2 shown in FIG. 2 can be manufactured, for example. The touch panel 2 includes a display module 3, a first film sensor 5a laminated thereon with an adhesive layer 4 interposed thereon, and a second film sensor 5a laminated thereon with an adhesive layer 11 interposed thereon. The film sensor 5b and the cover material 6 laminated|stacked via the adhesive layer 11 thereon are provided, and it is comprised.

The pressure-sensitive adhesive layer 11 in the touch panel 2 is the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 .

Examples of the display 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 may be formed of the adhesive layer 11 of the said adhesive sheet 1, and may be formed of another adhesive or an adhesive sheet. In the latter case, examples of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 4 include an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, and a polyvinyl ether-based pressure-sensitive adhesive. Among them, an acrylic pressure-sensitive adhesive is preferred. .

The 1st film sensor 5a and the 2nd film sensor 5b in this embodiment are equipped with the base film 51 and the electrode 52 which consists of the metal mesh formed in the base film 51, respectively. Although it does not specifically limit as the base film 51, For example, a polyethylene terephthalate film, an acrylic film, a polycarbonate film, etc. are used.

Although copper, silver, etc. are mentioned as a metal of the metal mesh which comprises the electrode 52, Copper is especially preferable. According to copper, the resistance value can be lowered to 10 Ω/square or less, and the touch panel can be enlarged. However, copper is easy to corrode compared with noble metals, such as platinum, gold|metal|money, silver, and also compared with transparent electrically-conductive materials, such as tin-doped indium oxide (ITO). However, according to the adhesive layer 11 formed from the adhesive composition P mentioned above, corrosion of the electrode 52 which consists of a copper mesh can be suppressed.

As for the electrode 52 of the 1st film sensor 5a and the electrode 52 of the 2nd film sensor 5b, one normally comprises a circuit pattern of an X-axis direction, and the other comprises a circuit pattern of a Y-axis direction. do.

The electrode 52 of the 2nd film sensor 5b in this embodiment is located above the 2nd film sensor 5b in FIG. On the other hand, although the electrode 52 of the 1st film sensor 5a is located above the 1st film sensor 5a in FIG. 2, it is not limited to this, It is located below the 1st film sensor 5a also be

The cover material 6 mainly has 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/strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, and barium borosilicate glass. have. It does not specifically limit as a plastic board, For example, the acrylic board which consists of polymethyl methacrylate etc., a polycarbonate board, etc. are mentioned.

In addition, functional layers, such as a hard coat layer, an antireflection layer, and a glare layer, may be formed on one side or both surfaces of the said glass plate or a plastic plate, Even if optical members, such as a hard coat film, an antireflection film, and an antiglare film, are laminated|stacked do.

In the present embodiment, the cover material 6 has a level difference on the surface on the pressure-sensitive adhesive layer 11 side, and specifically has a level difference depending on the presence or absence of the printed layer 7 . The printing layer 7 is generally formed in a frame shape on the pressure-sensitive adhesive layer 11 side of the cover material 6 .

The material constituting the printed layer 7 is not particularly limited, and a known material for printing is used. It is preferable that the thickness of the printed layer 7, ie, the height of a level difference is 3-45 micrometers, it is more preferable that it is 5-35 micrometers, It is especially preferable that it is 7-25 micrometers, It is more preferable that it is 7-15 micrometers. .

Moreover, it is preferable that the thickness (height of a step) of the printing layer 7 is 3 to 30 % of the thickness of the adhesive layer 11, It is especially preferable that it is 3.2 to 20 %, Furthermore, it is 3.5 to 15 %. it is preferable Thereby, the adhesive layer 11 is easy to follow the level|step difference by the printed layer 7, and it is suppressed that a float, a bubble, etc. generate|occur|produce in the step|step difference vicinity.

An example of the manufacturing method of the said touch panel 2 is demonstrated below.

As the pressure-sensitive adhesive sheet 1 , a first pressure-sensitive adhesive sheet 1 and a second pressure-sensitive adhesive sheet 1 are prepared. One peeling sheet 12a is peeled off from the 1st adhesive sheet 1, and the exposed adhesive layer 11 (1st adhesive layer 11) is in contact with the electrode 52 of the 2nd film sensor 5b. It bonds with the said 2nd film sensor 5b so that it may be. Moreover, one peeling sheet 12a is peeled from the 2nd adhesive sheet 1, so that the exposed adhesive layer 11 (2nd adhesive layer) may contact with the electrode 52 of the 1st film sensor 5a. It bonds with the said 1st film sensor 5a.

And the 2nd adhesive layer 11 which peels the other peeling sheet 12b in a 2nd adhesive sheet, and the 1st adhesive layer 11 in the said 2nd film sensor 5b is exposed Both are bonded together so that it may contact|connect the surface (exposed surface of the base film 51 of the 2nd film sensor 5b) on the opposite side to the laminated|stacked side. Thereby, the laminated body in which the release sheet 12b, the 1st adhesive layer 11, the 2nd film sensor 5b, the 2nd adhesive layer 11, and the 1st film sensor 5a are laminated|stacked in order is obtained. .

Next, the adhesive layer 4 formed on the release sheet is bonded to the surface (exposed surface of the base film 51 of the 1st film sensor 5a) on the side of the 1st film sensor 5a of the said laminated body. . Then, the release sheet 12b is peeled from the laminate, and with respect to the exposed first pressure-sensitive adhesive layer 11 , the printed layer 7 side of the cover material 6 is in contact with the pressure-sensitive adhesive layer 11 . , the cover member 6 is bonded together. Thereby, the cover material 6, the 1st adhesive layer 11, the 2nd film sensor 5b, the 2nd adhesive layer 11, the 1st film sensor 5a, the adhesive layer 4, and the release sheet|seat A structure in which is sequentially laminated is obtained.

Finally, the release sheet is peeled from the structure, and the structure is bonded to the display module 3 so that the exposed pressure-sensitive adhesive layer 4 is in contact with the display module 3 . Thereby, the touch panel 2 shown in FIG. 2 is manufactured.

Even when the touch panel 2 is returned to normal temperature and humidity after being placed under high temperature and high humidity conditions (eg, 85° C. and 85% RH for 240 hours), the pressure-sensitive adhesive layer 11 (first pressure-sensitive adhesive layer 11) ) and 2nd adhesive layer 11), since it is excellent in heat-and-moisture whitening resistance, whitening is suppressed. Specifically, the haze value of the pressure-sensitive adhesive layer 11 can be maintained at 1.0% or less.

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

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

Example

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

[Example 1]

1. Preparation of (meth)acrylic acid ester copolymer

60 mass parts of 2-ethylhexyl acrylate, 20 mass parts of methyl methacrylate, and 20 mass parts of acrylic acid 2-hydroxyethyl were copolymerized, and the (meth)acrylic acid ester polymer (A) was prepared. It was a weight average molecular weight (Mw) 600,000 when the molecular weight of this (meth)acrylic acid ester polymer (A) was measured by the method mentioned later.

2. Preparation of adhesive composition

100 parts by mass of the (meth)acrylic acid ester polymer (A) obtained in the step (1) (solid content conversion; the same hereinafter) and 1H-benzotriazole as a benzotriazole-based rust preventive agent (B) (manufactured by Johoku Chemical Co., Ltd., Product name "BT-120") 0.3 parts by mass, trimethylolpropane-modified tolylene diisocyanate as a crosslinking agent (C) (made by Nippon Polyurethane, product name "Coronate L") 0.15 parts by mass, 3-glycol as a silane coupling agent 0.2 parts by mass of cidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-403") is mixed, thoroughly stirred, and diluted with methyl ethyl ketone, whereby a coating solution of an adhesive composition having a solid content concentration of 25 mass % got

Here, the formulation of the said adhesive composition is shown in Table 1. In addition, details, such as abbreviation of Table 1, are as follows.

[(meth)acrylic acid ester polymer (A)]

2EHA: 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 Cyprocasei, 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. Preparation of adhesive sheet

The coating solution of the obtained pressure-sensitive adhesive composition was applied to the release-treated surface of a medium-peelable release sheet (manufactured by Lintec, product name "SP-PET382150", thickness: 38 µm) in which one side of a polyethylene terephthalate film was peeled off with a silicone release agent, after drying. After apply|coating with a knife coater so that thickness might be set to 50 micrometers, it heat-processed at 90 degreeC for 1 minute, and formed the application layer.

The light-peelable release sheet (manufactured by Lintec, product name "SP-PET382120", thickness: 38 µm) of a light-peelable release sheet (manufactured by Lintec, product name "SP-PET382120", thickness: 38 µm) in which one side of a polyethylene terephthalate film is peeled off with a silicone-based release agent is in contact with the coating layer, The sheet was bonded to the application layer. Then, the adhesive sheet which consists of a structure of a medium-peelable release sheet/adhesive layer (thickness: 50 micrometers)/light-peelable release sheet was manufactured by curing on the conditions of 23 degreeC and 50 %RH for 7 days.

[Examples 2-5, Comparative Examples 1-2]

The type and ratio of each monomer constituting the (meth)acrylic acid ester polymer (A), the weight average molecular weight (Mw) of the (meth)acrylic acid ester polymer (A), and the type of the benzotriazole-based rust inhibitor (B) are shown in Table 1 Except changing as shown, it carried out similarly to Example 1, and produced the adhesive sheet.

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

<Measurement conditions>

・GPC measuring device: HLC-8020 manufactured by Tosoh Corporation

・GPC column (passed in the following order): manufactured by Tosoh Corporation

TSK guard column HXL-H

TSK gel GMHXL (×2)

TSK gel G2000HXL

·Measurement solvent: tetrahydrofuran

・Measurement temperature: 40℃

[Test Example 1] (Evaluation of whitening resistance in moist heat)

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet obtained in the Examples and Comparative Examples is sandwiched between two sheets of alkali-free glass (thickness: 1 mm) of a size of 70 mm × 70 mm, and the laminate is 30° C. under the conditions of 0.5 MPa. Minute autoclave treatment was carried out, and this was used as a sample.

The obtained sample was stored under the wet heat conditions of 85 degreeC and 85 %RH for 240 hours. Then, it returned to the atmosphere of 23 degreeC and 50 %RH (normal temperature and normal humidity), and the haze value of the adhesive layer was measured. The haze value was measured using a haze meter (manufactured by Nippon Denshoku Co., Ltd., product name "NDH-5000") according to JIS K7136:2000 within 30 minutes after returning the sample to the atmosphere of normal temperature and humidity. Based on the measured haze value, the following reference|standard evaluated heat-and-moisture whitening resistance. A result is shown in Table 1.

○: haze value was 1.0% or less

x: haze value was more than 1.0%

[Test Example 2] (Evaluation of corrosion inhibition)

(1) Fabrication of copper mesh laminated film

Polyethylene terephthalate (PET) film (manufactured by Toyobo Seki Co., Ltd., product name "PET100A4100", thickness: 100 µm) and one side blackened copper foil (manufactured by Furukawa Circuit Foil, product name "BW-S", thickness: 10 µm) ) and a polyurethane adhesive (manufactured by Takedayaku Hinko Co., Ltd., Takelac A310/Takenate A10/ethyl acetate = 12/1/21 (mass ratio)) were prepared.

Using the polyurethane adhesive, the surface on the opposite side to the blackening treatment surface of the copper foil and the PET film were bonded to obtain a laminate comprising PET film/adhesive layer/copper foil.

Casein was apply|coated to the copper foil side (blackening process surface) of the obtained laminated body, it was made to dry, and it was set as the photosensitive resin layer. And the close_contact exposure of the ultraviolet-ray was performed with respect to the said photosensitive resin layer through the mask in which the pattern was formed, and it developed with water. As the mask, a mask having a pattern having a line width of 10 µm and a pitch of 300 µm was used. Then, after hardening process, baking was performed at 100 degreeC, and the resist pattern was formed.

The laminate on which the resist pattern was formed was etched by spraying a ferric chloride solution (Bomedo: 42, temperature: 30° C.) from the resist pattern side, followed by washing with water. Next, after peeling a resist pattern using an alkali solution, washing|cleaning and drying process were performed. In this way, the copper mesh laminated|multilayer film which consists of PET film/adhesive layer/copper mesh was obtained.

(2) Corrosion inhibition evaluation

The light-peelable release sheet was peeled from the adhesive sheet obtained by the Example and the comparative example, and the exposed adhesive layer was affixed on the copper mesh side of the said copper mesh laminated|multilayer film. Thereafter, the heavy release type release sheet was peeled from the pressure-sensitive adhesive layer, and a PET film (manufactured by Toyobo Seki Corporation, product name “PET A4100”, thickness: 100 μm) was affixed to the exposed pressure-sensitive adhesive layer, and PET film/adhesive layer/copper A laminate comprising a mesh/adhesive layer/PET film was obtained, and this was used as a sample.

The sample was stored for 250 hours at 85°C and under moist heat conditions of 85%RH. Then, the presence or absence of corrosion of a copper mesh was confirmed visually, and the following reference|standard evaluated corrosion suppression performance. A result is shown in Table 1.

○: There was no corrosion in the copper mesh

x: There was corrosion in the copper mesh

[Test Example 3] (Calculation of dielectric constant)

After forming a 100-micrometer-thick adhesive layer on the single side|surface of a 50-micrometer-thick polyethylene terephthalate film like an Example and a comparative example, and bonding a 50-micrometer-thick polyethylene terephthalate film together on the adhesive layer, 50 mm It cut to x50 mm. About the obtained laminated body, the electrostatic capacitance (C1) was measured using the impedance analyzer (The Nippon Hewlett-Packard company make, "HP-4194A"). Moreover, the said 50-micrometer-thick polyethylene terephthalate film overlapped 2 sheets, it cut out to 50 mm x 50 mm, it carried out similarly, and the electrostatic capacitance (C2) was measured. And the electrostatic capacitance (C3) of the adhesive was computed by subtracting C2 from C1. Based on this electrostatic capacitance C3, the dielectric constant ε _s of the pressure-sensitive adhesive was calculated from the following formula. A result is shown in Table 1.

ε _s =(C3×d)/(ε ₀ ×S)

ε _s : permittivity of adhesive

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

C3: electrostatic capacity of adhesive

S: area of the pressure-sensitive adhesive layer

d: the thickness of the pressure-sensitive adhesive layer

From the above result, the dielectric constant ε _s of the pressure-sensitive adhesive layer evaluated a thing of 2.0-8.0 as good (circle) and a thing exceeding 8.0 as bad (x). This evaluation result is also shown in Table 1 collectively.

As Table 1 shows, the adhesive sheet obtained in the Example was excellent in moist-and-heat resistance whitening property and a corrosion inhibitory effect, and also the dielectric constant was low enough and it was favorable.

The pressure-sensitive adhesive composition, pressure-sensitive adhesive, and pressure-sensitive adhesive sheet according to the present invention can be preferably used for, for example, a capacitive touch panel using a copper mesh as an electrode.

1: adhesive sheet
11: adhesive layer
12a, 12b: release sheet
2: Touch panel
3: display module
4: adhesive layer
5a: first film sensor
5b: second film sensor
51: base film
52: electrode
6: cover material
7: print layer

Claims (5)

A film sensor in which an electrode of a metal mesh containing copper is formed;
a pressure-sensitive adhesive layer disposed in contact with the metal mesh of the film sensor;
The pressure-sensitive adhesive layer,
30% by mass or more of 2-ethylhexyl (meth)acrylic acid as a monomer unit constituting the polymer, 10% by mass or more of a hard monomer having a glass transition temperature of 70° C. or higher as a homopolymer, and 15% by mass of a monomer having a hydroxyl group The (meth)acrylic acid ester polymer (A) which contains more than % and 30 mass % or less and does not contain the monomer which has a carboxyl group;
Benzotriazole rust inhibitor (B)
Consists of a pressure-sensitive adhesive formed by crosslinking the pressure-sensitive adhesive composition containing
A thickness of the pressure-sensitive adhesive layer is 25 µm or more and 300 µm or less. The benzotriazole-based rust inhibitor (B) according to claim 1, wherein 1H-benzotriazole, 1H-tolyltriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole and 1 A construct comprising at least one selected from the group consisting of -[N,N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole. The composition according to claim 1, wherein the pressure-sensitive adhesive composition further contains a crosslinking agent (C). The construct according to claim 1, wherein the pressure-sensitive adhesive has a dielectric constant at 1.0 MHz of 2.0 to 8.0. The touch panel which has the structure in any one of Claims 1-4.

Images