JP2022178906A - Optical adhesive sheet - Google Patents

Abstract

An optical pressure-sensitive adhesive sheet having excellent corrosion resistance to a silver nanowire layer is provided. The optical pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer in which the weight ratio of I below to I0 below (I/I0) is 0.05 or less. I0: Iodine ion elution amount (ppm) when a polarizing plate of 9 cm2 attached to a glass plate was immersed in 150 ml of water at 85°C and stored for 24 hours I: The adhesive layer attached to the glass plate and having a thickness of 100 µm. Iodine ion elution amount (ppm) when a 9 cm2 polarizing plate covered with

Description

TECHNICAL FIELD The present invention relates to an optical pressure-sensitive adhesive sheet.

BACKGROUND ART Conventionally, a transparent optical pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer has been used to bond a liquid crystal display device or an organic EL display device to a sensor film (for example, Patent Documents 1 to 3).

On the other hand, iodine-containing polyvinyl alcohol sheets are often used as polarizing plates on the surface of image display devices such as liquid crystal display devices and organic EL display devices because they have the advantage of having both high transmittance and high degree of polarization. A transparent optical pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer is also used for bonding the plate and the sensor film.

JP 2003-238915 A JP-A-2003-342542 Japanese Patent Application Laid-Open No. 2004-231723

In recent years, an optical sensor having a silver nanowire layer is often used as a sensor film, and since the silver nanowire layer is easily corroded, there is a demand for an optical adhesive sheet that can suppress the corrosion of the silver nanowire layer. .

Accordingly, an object of the present invention is to provide an optical pressure-sensitive adhesive sheet that effectively suppresses corrosion of a silver nanowire layer of an optical sensor.

As a result of intensive studies to achieve the above object, the present inventors found that by reducing the permeation amount of iodine ions in the optical pressure-sensitive adhesive sheet to a specific amount or less, the corrosion of the silver nanowire layer of the optical sensor can be effectively prevented. The present invention has been completed by finding that it can be suppressed to .

That is, the present invention provides an optical pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer in which the weight ratio (I/I ₀ ) of I below to I ₀ below is 0.05 or less.
I ₀ : Iodine ion elution amount (ppm) when a 9 cm ² polarizing plate attached to a glass plate was immersed in 150 ml of water at 85° C. and stored for 24 hours.
I: Iodine ion elution amount (ppm) when a 9 cm ² polarizing plate attached to a glass plate and covered with the adhesive layer having a thickness of 100 μm was immersed in 150 ml of water at 85° C. for 24 hours.

The pressure-sensitive adhesive layer preferably contains, as a base polymer, an acrylic polymer having a unit derived from a nitrogen atom-containing monomer.

In the pressure-sensitive adhesive layer, the thickness X (μm) of the pressure-sensitive adhesive layer and the content ratio Y (% by weight) of the unit derived from the nitrogen atom-containing monomer in the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer are as follows. It is preferable to satisfy formula (1).
20.0≦(X×Y/100)≦120.0 (1)

Preferably, the pressure-sensitive adhesive layer has a moisture permeability of 500 g/(m ² ·24 h) or less at 40° C. and 92% RH when the thickness is 100 μm.

In the pressure-sensitive adhesive layer, the thickness X (μm), the content ratio Y (% by weight), and the moisture permeability Z (g/(m ² 24 h)), which is the moisture permeability, satisfy the following formula (2). preferably fulfilled.
10.0≦(X×Y/Z)≦120.0 (2)

The above acrylic polymer preferably has a group containing a linear or branched alkyl group having 8 to 18 carbon atoms in the side chain.

The present invention also provides an image display device comprising a polarizing plate, the optical pressure-sensitive adhesive sheet, and an optical sensor in this order.

Since the optical pressure-sensitive adhesive sheet of the present invention can effectively suppress the corrosion of the silver nanowire layer of the optical sensor bonded to the polarizing plate due to iodine ions, it is suitably used for bonding the polarizing plate and the optical sensor. be able to.

1 is a schematic cross-sectional view showing an example of an image display device using the optical pressure-sensitive adhesive sheet of the present invention; FIG.

As shown in FIG. 1, the optical pressure-sensitive adhesive sheet of the present invention adheres a polarizing plate 3 and an optical sensor 6 together, effectively suppresses the transmission of iodine ions exuding from the polarizing plate 3, and suppresses the transmission of silver by iodine ions. It is preferably used as an adhesive layer 2a that suppresses corrosion of the nanowire layer 4. The optical pressure-sensitive adhesive sheet of the present invention also has the effect of suppressing the permeation of moisture and suppressing the detachment and exudation of iodine ions from the polarizing plate. ) can also be used as The optical pressure-sensitive adhesive sheet of the present invention can also be used, for example, as the pressure-sensitive adhesive layer 2b for bonding the optical sensor 6 and the image display panel 7 together.

The optical pressure-sensitive adhesive sheet of the present invention is an optical pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer in which the weight ratio of I below to I ₀ below (I/I ₀ ) is 0.05 or less.
I ₀ : Iodine ion elution amount (ppm) when a 9 cm ² polarizing plate attached to a glass plate was immersed in 150 ml of water at 85° C. and stored for 24 hours.
I: Iodine ion elution amount (ppm) when a 9 cm ² polarizing plate attached to a glass plate and covered with the adhesive layer having a thickness of 100 μm was immersed in 150 ml of water at 85° C. for 24 hours.

The configuration in which the weight ratio (I/I ₀ ) is 0.05 or less prevents the silver nanowire layer from being corroded by iodine ions in the optical sensor attached to the polarizing plate using the optical pressure-sensitive adhesive sheet of the present invention. This is preferable in that it can be effectively suppressed.

The weight ratio (I/I ₀ ) is 0.05 or less, preferably 0.04 or less, more preferably 0.03 or less, and still more preferably 0.02 or less. Although the lower limit is not particularly limited, it is preferably 0.005. When the weight ratio (I/I ₀ ) is 0.05 or less, corrosion of the silver nanowire layer is less likely to occur in the optical sensor attached to the polarizing plate via the optical pressure-sensitive adhesive sheet of the present invention. The weight ratio (I/I ₀ ) is such that when the optical pressure-sensitive adhesive sheet of the present invention is adhered to an iodine-containing polyvinyl alcohol sheet as a polarizing plate, the iodine ions exuded from the polarizing plate are equal to the optical pressure-sensitive adhesive of the present invention. It is an index representing the degree of permeation through the sheet, and the smaller the value, the more suppressed the permeation of iodide ions.

The iodine ion elution amounts I ₀ and I can be measured, for example, by the ion chromatography method described in Examples.

From the viewpoint of measurement accuracy, the polarizing plate used for measuring the iodine ion elution amounts I ₀ and I preferably has an iodine ion elution amount I ₀ of 2.0 ppm or more.

The above weight ratio (I/I ₀ ) can be set within a preferred range, for example, by appropriately adjusting the type and content of units derived from nitrogen atom-containing monomers in the following acrylic polymer.

The optical pressure-sensitive adhesive sheet of the present invention is a double-sided pressure-sensitive adhesive sheet having pressure-sensitive adhesive surfaces on both sides. Both pressure-sensitive adhesive surfaces of the optical pressure-sensitive adhesive sheet of the present invention may be formed of the same pressure-sensitive adhesive layer, or may be formed of different pressure-sensitive adhesive layers. When formed with different pressure-sensitive adhesive layers, the weight ratio (I/I ₀ ) in the entire pressure-sensitive adhesive sheet may fall within the above range.

The optical pressure-sensitive adhesive sheet of the present invention may be a "substrate-less pressure-sensitive adhesive sheet" having no substrate (substrate layer), or may be a "substrate-attached pressure-sensitive adhesive sheet" having a substrate.

The substrate (substrate layer) is a support that supports the pressure-sensitive adhesive layer. be.

Examples of the base material include polyester resins (polyethylene terephthalate, etc.), acrylic resins (polymethyl methacrylate, etc.), polycarbonate, triacetyl cellulose, polysulfone, polyarylate, polyimide, polyvinyl chloride, polyvinyl acetate, Plastics made from polyethylene, polypropylene, ethylene-propylene copolymers, cyclic olefin polymers (trade name “Arton” (manufactured by JSR Corporation), trade name “Zeonor” (manufactured by Nippon Zeon Co., Ltd.), etc.) film. These plastic materials may be used alone or in combination of two or more. A release liner that is released from the adhesive surface during application is not included in the base material.

The total light transmittance of the base material measured according to JIS K7136 is preferably 85% or more, more preferably 88% or more. Moreover, the haze of the base material measured according to JIS K7136 is not particularly limited, but is preferably 1.0% or less, more preferably 0.5% or less.

Although the thickness of the substrate is not particularly limited, it is preferably 12 to 75 μm, for example. The substrate may be in the form of a single layer or multiple layers. surface treatment may be applied.

The optical pressure-sensitive adhesive sheet of the present invention may have a release liner on the surface (adhesive surface) of the pressure-sensitive adhesive layer until the time of sticking. Each adhesive surface may be protected by two release liners, or may be protected in a rolled form (wound body) by one release liner having release surfaces on both sides. may be

Examples of the release liner include a substrate having a release treatment layer, a low-adhesion substrate made of a fluoropolymer, a low-adhesion substrate made of a nonpolar polymer, and the like. The release liner can be formed by a known or commonly used method, and its thickness is not particularly limited.

Examples of substrates having a release treatment layer include plastic films and papers surface-treated with release agents such as silicone, long-chain alkyl, fluorine, and molybdenum sulfide.

Examples of the fluorine-based polymer in the low-adhesive substrate made of the fluorine polymer include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, chloro Examples include fluoroethylene-vinylidene fluoride copolymers.

Examples of the non-polar polymer include olefin resins (eg, polyethylene, polypropylene, etc.).

The pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer according to the present invention is not particularly limited as long as the weight ratio (I/I ₀ ) is within the preferable range. Adhesive compositions, vinyl alkyl ether-based adhesive compositions, silicone-based adhesive compositions, polyester-based adhesive compositions, polyamide-based adhesive compositions, urethane-based adhesive compositions, fluorine-based adhesive compositions, epoxies system pressure-sensitive adhesive composition and the like. Among them, an acrylic pressure-sensitive adhesive composition is preferable because it is easy to design the pressure-sensitive adhesive composition with respect to transparency, adhesiveness, weather resistance, cost, and the like. Only one kind of the above pressure-sensitive adhesive composition may be used, or two or more kinds thereof may be used.

The acrylic pressure-sensitive adhesive composition contains an acrylic polymer as a base polymer. Only one type of the acrylic polymer may be used, or two or more types may be used.

The acrylic polymer preferably has a unit derived from a (meth)acrylic acid alkyl ester. In addition, "(meth)acryl" represents "acryl" and/or "methacryl" (one or both of "acryl" and "methacryl"), and the same applies below. The acrylic polymer may be a random copolymer or a block copolymer.

The acrylic polymer may contain unpolymerized monomers or oligomers thereof.

The acrylic polymer according to the present invention preferably has a unit derived from a nitrogen atom-containing monomer because it is believed that nitrogen atoms in the structure are coordinated with iodide ions to suppress permeation of iodide ions. Details of the nitrogen atom-containing monomer will be described later.

In the pressure-sensitive adhesive layer according to the present invention, the thickness X (μm) of the pressure-sensitive adhesive layer and the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer (such as the acrylic polymer and additives blended in the acrylic polymer) It is preferable that the content ratio Y (% by weight) of the unit derived from the nitrogen atom-containing monomer in the total) satisfies the following formula (1).
20.0≦(X×Y/100)≦120.0 (1)

The above value (X×Y/100) is an index of the amount of nitrogen atoms present on the path along which iodine ions try to permeate the pressure-sensitive adhesive layer.

When the value (X×Y/100) according to the formula (1) is 20.0 or more and 120.0 or less, the pressure-sensitive adhesive layer effectively captures and transmits iodide ions while maintaining good transparency. This is preferable in that it becomes easier to suppress the

The above value (X×Y/100) is more preferably 22.0 or more, still more preferably 25.0 or more, from the viewpoint that the pressure-sensitive adhesive layer can effectively trap iodide ions, and the pressure-sensitive adhesive layer is more preferably 100.0 or less, still more preferably 80.0 or less, from the viewpoint that good transparency can be easily maintained.

The thickness X of the pressure-sensitive adhesive layer is preferably 90 μm or more, more preferably 95 μm or more, and still more preferably 100 μm or more from the viewpoint of easily suppressing the permeation of iodine ions and moisture while having sufficient adhesion reliability. From the viewpoint of maintaining sufficient transparency, the thickness is preferably 300 μm or less, more preferably 270 μm or less, and even more preferably 230 μm or less.

The content ratio Y is preferably 20.0% by weight or more, more preferably 23.0% by weight or more, and still more preferably 25.0% by weight or more, in order to easily suppress the permeation of iodide ions. It is preferably 40.0% by weight or less, more preferably 37.0% by weight or less, and even more preferably 35.0% by weight or less, because it is easy to suppress.

The pressure-sensitive adhesive layer preferably has a moisture permeability of 500 g/(m ² ·24 h) or less at 40° C. and 92% RH when the thickness is 100 μm.

When the moisture permeability is 500 g/(m ² ·24 h) or less, the pressure-sensitive adhesive layer suppresses the permeation of moisture, that is, the penetration of moisture into the polarizing plate, and the iodide ions desorb and exude from the polarizing plate due to the moisture. can be suppressed. The moisture permeability can be measured by the method described in Examples.

The moisture permeability is more preferably 400 g/(m ² ·24 h) or less, still more preferably 300 g/(m ² ·24 h) or less. The lower limit of the moisture permeability is not particularly limited, but may be, for example, 15 g/(m ² ·24 h), 20 g/(m ² ·24 h) or 25 g/(m ² ·24 h).

In the pressure-sensitive adhesive layer, the thickness X (μm) of the pressure-sensitive adhesive layer, the content ratio Y (% by weight) of the unit derived from the nitrogen atom-containing monomer in the pressure-sensitive adhesive composition, and the moisture permeability Z which is the moisture permeability (g/(m ² ·24h)) preferably satisfies the following formula (2).
10.0≦(X×Y/Z)≦120.0 (2)

The above value (X×Y/Z) is an index of the easiness of movement of water and iodine in the adhesive.

When the value (X×Y/Z) in the above formula (2) is 10.0 or more and 120.0 or less, the pressure-sensitive adhesive layer suppresses the penetration of moisture into the polarizing plate, resulting in This is preferable in that it can suppress the separation of iodine ions from the polarizing plate.

The above value (X×Y/Z) is more preferably 11.0 or more, still more preferably 12.0 or more. The upper limit of the above value (X×Y/Z) is more preferably 110.0, still more preferably 100.0.

The above value (X×Y/100), the above moisture permeability, and the above value (X×Y/Z) are, for example, in the following acrylic polymer, (meth)acrylic acid alkyl ester, nitrogen atom-containing monomer, hydroxyl group-containing By appropriately adjusting the type and content of units derived from monomers, etc., the value can be set within a preferable range.

The pressure-sensitive adhesive composition that forms the pressure-sensitive adhesive layer includes, for example, emulsion type, solvent type (solution type), active energy rays (α rays, β rays, γ rays, neutron rays, ionizing radiation such as electron beams, ultraviolet rays etc.), a heat melting type (hot melt type), or the like.

The acrylic polymer according to the present invention preferably has a unit derived from a (meth)acrylic acid alkyl ester having a linear or branched alkyl group at the ester end. The acrylic polymer can have a group containing an alkyl group in a side chain by having a unit derived from the (meth)acrylic acid alkyl ester.

The alkyl group preferably has 1 to 20 carbon atoms, and specific examples of the (meth)acrylic acid alkyl ester include methyl (meth)acrylate, ethyl (meth)acrylate, and (meth)acrylic acid. propyl, isopropyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate , isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, Pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, etc. is mentioned.

Among them, (meth)acrylic acid alkyl ester having an alkyl group having 8 to 18 carbon atoms (preferably a branched chain alkyl group) is preferable, and 2-ethylhexyl acrylate, because it is easy to suppress moisture permeation of the pressure-sensitive adhesive layer. , and isostearyl acrylate are more preferred.

The content of the (meth)acrylic acid alkyl ester-derived units in the acrylic polymer is preferably 65.0% by weight or more, more preferably 68.0% by weight, based on 100% by weight of all monomer-derived units. % or more, more preferably 70.0% by weight or more. The upper limit is preferably 80.0% by weight, more preferably 78.0% by weight, still more preferably 75.0% by weight. When the content of the (meth)acrylic acid alkyl ester-derived unit is within the above range, it becomes easier to balance the adhesive force and the cohesive force.

The content of the unit derived from the (meth)acrylic acid alkyl ester having an alkyl group having 8 to 18 carbon atoms is 70.0% by weight with respect to 100% by weight of the (meth)acrylic acid alkyl ester-derived unit. The above is preferable, more preferably 75.0% by weight or more, and still more preferably 80.0% by weight or more. The upper limit may be, for example, 100% by weight, or 98.0% by weight or 95.0% by weight.

Only one type of the (meth)acrylic acid alkyl ester may be used, or two or more types may be used.

The acrylic polymer preferably has a unit derived from another monomer (copolymerizable monomer) having a (meth)acryloyl group or alkenyl group that can be polymerized with the (meth)acrylic acid alkyl ester. Examples of the copolymerizable monomer include nitrogen atom-containing monomers and hydroxyl group-containing monomers.

Examples of the nitrogen atom-containing monomer include cyclic nitrogen-containing monomers and (meth)acrylamides.

Examples of the cyclic nitrogen-containing monomer include N-vinyl cyclic amides (lactam vinyl monomers), vinyl monomers having a nitrogen-containing heterocycle, amino group-containing monomers, cyano group-containing monomers, imide group-containing monomers, isocyanate group-containing monomers, A monomer etc. are mentioned.

Examples of the N-vinyl cyclic amides include N-vinyl cyclic amides represented by the following formula (3). In formula (3), R ¹ represents a divalent organic group.

R ¹ in the above formula (1) is a divalent organic group, preferably a divalent saturated hydrocarbon group or an unsaturated hydrocarbon group, more preferably a divalent saturated hydrocarbon group (e.g., carbon number 3 to 5 alkylene groups, etc.).

Examples of the N-vinyl cyclic amide represented by the formula (3) include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone and N-vinyl-2-caprolactam. , N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, and the like.

Examples of vinyl monomers having a nitrogen-containing heterocyclic ring include acrylic monomers having a nitrogen-containing heterocyclic ring such as a morpholine ring, a piperidine ring, a pyrrolidine ring, and a piperazine ring.

Examples of vinyl-based monomers having a nitrogen-containing heterocyclic ring include (meth)acryloylmorpholine, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole, N-vinylpyrazine, N-vinylmorpholine, N-vinylpyrazole , vinylpyridine, vinylpyrimidine, vinyloxazole, vinylisoxazole, vinylthiazole, vinylisothiazole, vinylpyridazine, (meth)acryloylpyrrolidone, (meth)acryloylpyrrolidine, (meth)acryloylpiperidine and the like.

Examples of the (meth)acrylamides include (meth)acrylamide, N-alkyl(meth)acrylamide, N,N-dialkyl(meth)acrylamide and the like. Examples of the N-alkyl(meth)acrylamide include N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, Nn-butyl(meth)acrylamide, N-octyl(meth)acrylamide and the like. . Furthermore, the above N-alkyl(meth)acrylamides also include (meth)acrylamides having an amino group such as dimethylaminoethyl(meth)acrylamide, diethylaminoethyl(meth)acrylamide, and dimethylaminopropyl(meth)acrylamide. Examples of the N,N-dialkyl(meth)acrylamides include N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl (Meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, N,N-di(t-butyl)(meth)acrylamide and the like.

The (meth)acrylamides also include, for example, various N-hydroxyalkyl(meth)acrylamides. Examples of the N-hydroxyalkyl(meth)acrylamide include N-methylol(meth)acrylamide, N-(2-hydroxyethyl)(meth)acrylamide, N-(2-hydroxypropyl)(meth)acrylamide, N- (1-hydroxypropyl)(meth)acrylamide, N-(3-hydroxypropyl)(meth)acrylamide, N-(2-hydroxybutyl)(meth)acrylamide, N-(3-hydroxybutyl)(meth)acrylamide, N-(4-hydroxybutyl)(meth)acrylamide, N-methyl-N-2-hydroxyethyl(meth)acrylamide and the like.

The (meth)acrylamides also include, for example, various N-alkoxyalkyl(meth)acrylamides. Examples of the N-alkoxyalkyl(meth)acrylamides include N-methoxymethyl(meth)acrylamide and N-butoxymethyl(meth)acrylamide.

Examples of the amino group-containing monomer include aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, t-butylaminoethyl (meth)acrylate, and the like. .

Examples of the cyano group-containing monomer include acrylonitrile and methacrylonitrile.

Examples of the imide group-containing monomer include maleimide-based monomers (eg, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, etc.), itaconimide-based monomers (eg, N-methylitaconimide, N- ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-laurylitaconimide, N-cyclohexylitaconimide, etc.), succinimide-based monomers (e.g., N-(meth)acryloyl oxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, N-(meth)acryloyl-8-oxyoctamethylenesuccinimide, etc.).

Examples of the isocyanate group-containing monomer include 2-(meth)acryloyloxyethyl isocyanate.

Among the nitrogen atom-containing monomers, cyclic nitrogen-containing monomers are preferred, N-vinyl cyclic amides are more preferred, and N-vinyl-2-pyrrolidone is even more preferred.

Only one kind of the nitrogen atom-containing monomer may be used, or two or more kinds thereof may be used.

The content of the units derived from the nitrogen atom-containing monomer in the acrylic polymer is preferably 20.0% by weight or more, more preferably 23.0% by weight or more, based on 100% by weight of all monomer-derived units. More preferably, it is 25.0% by weight or more. The upper limit is preferably 40.0% by weight, more preferably 37.0% by weight, still more preferably 35.0% by weight. When the content of the unit derived from the nitrogen atom-containing monomer is 20.0% by weight or more, the permeation of iodide ions is easily suppressed, and when the upper limit is 40.0% by weight, the coloring of the pressure-sensitive adhesive layer is suppressed. Cheap.

Examples of the hydroxyl group-containing monomers include hydroxyl group-containing (meth)acrylic acid esters, vinyl alcohol, and allyl alcohol.

Examples of the hydroxyl group-containing (meth)acrylic acid esters include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4 (meth)acrylic acid. -hydroxybutyl, 6-hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, hydroxyllauryl (meth)acrylate, (4-hydroxymethylcyclohexyl) (meth)acrylate etc., among which 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are preferred.

Only one kind of the hydroxyl group-containing monomer may be used, or two or more kinds thereof may be used.

The content of the hydroxyl group-containing monomer-derived units in the acrylic polymer is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and still more preferably 100% by weight of all monomer-derived units. is 0.8% by weight or more. The upper limit is preferably 25.0% by weight, more preferably 10.0% by weight, and even more preferably 5.0% by weight. When the content of the unit derived from the hydroxyl group-containing monomer is 0.1% by weight or more, the adhesiveness of the pressure-sensitive adhesive composition and the degree of cross-linking due to reaction with the cross-linking agent can be easily adjusted, and the upper limit is 25.0. % by weight, the pressure-sensitive adhesive layer becomes less permeable to moisture.

In addition to the nitrogen atom-containing monomer and the hydroxyl group-containing monomer, the copolymerizable monomers include, for example, an alicyclic structure-containing monomer, a carboxy group-containing monomer, an acid anhydride group-containing monomer, a sulfonic acid group- or phosphoric acid group-containing monomer, an epoxy group containing monomers, alkoxy group-containing monomers, alkoxysilyl group-containing monomers, vinyl esters, vinyl alkyl ethers, aromatic hydrocarbon group-containing monomers, olefins, dienes, and the like.

Examples of the alicyclic monomers include (meth)acrylic acid cycloalkyl esters having a cycloalkyl group having 4 to 10 carbon atoms, (meth)acrylic acid esters having a bicyclic hydrocarbon ring, and tricyclic or higher (Meth)acrylic acid esters having a hydrocarbon ring of The cycloalkyl group, the bicyclic hydrocarbon ring, and the tricyclic or higher hydrocarbon ring may each have a substituent. Such substituents include halogen atoms (eg, fluorine atom, chlorine atom, bromine atom, iodine atom), straight-chain or branched-chain alkyl groups having 1 to 6 carbon atoms (eg, methyl group, ethyl group, n-propyl group, isopropyl group, etc.). The number of substituents is, for example, 1 to 6. Two or more substituents may be the same or different.

Examples of the above cycloalkyl (meth)acrylates include cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, Cyclooctyl (meth)acrylate and the like can be mentioned. Among them, cyclohexyl acrylate and 3,3,5-trimethylcyclohexyl methacrylate are preferred.

Examples of the (meth)acrylate having a bicyclic hydrocarbon ring include bornyl (meth)acrylate and isobornyl (meth)acrylate.

Examples of the (meth)acrylic acid ester having a hydrocarbon ring of three or more rings include dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclo(meth)acrylate, pentanyl, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate and the like.

Each of the alicyclic monomers may be used alone or in combination of two or more.

The content of the alicyclic monomer-derived units in the acrylic polymer is preferably 10.0% by weight or less, more preferably 5.0% by weight or less, based on 100% by weight of all monomer-derived units. More preferably, it is 3.0% by weight or less. The lower limit may be, for example, 0% by weight.

Examples of the carboxy group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

Acid anhydride group-containing monomers include, for example, maleic anhydride and itaconic anhydride.

In the acrylic polymer, the total content of units derived from carboxyl group-containing monomers and acid anhydride group-containing monomers is 1% by weight or less with respect to 100% by weight of all monomer-derived units from the viewpoint of metal corrosion prevention. and may be 0.5% by weight or less. The lower limit is usually 0% by weight, at least because it is preferable not to use it intentionally.

Examples of sulfonic acid group- or phosphoric acid group-containing monomers include styrenesulfonic acid, allylsulfonic acid, sodium vinylsulfonate, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfo Propyl (meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid, 2-hydroxyethyl acryloyl phosphate and the like.

Examples of epoxy group-containing monomers include epoxy group-containing acrylates such as glycidyl (meth)acrylate and 2-ethylglycidyl (meth)acrylate, allyl glycidyl ether, and glycidyl ether (meth)acrylate.

Examples of the alkoxy group-containing monomer include alkoxyalkyl (meth)acrylates, alkoxypolyalkyleneglycol (meth)acrylates, and the like.

Examples of the alkoxyalkyl (meth)acrylates include 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, and propoxyethyl (meth)acrylate. , butoxyethyl (meth)acrylate, ethoxypropyl (meth)acrylate, and the like.

Examples of the alkoxypolyalkylene glycol (meth)acrylates include methoxyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate.

Examples of the alkoxysilyl group-containing monomer include alkoxysilyl group-containing (meth)acrylates and alkoxysilyl group-containing vinyl compounds.

Examples of the alkoxysilyl group-containing vinyl compound include 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3- (Meth)acryloxypropylmethyldiethoxysilane and the like.

Examples of the vinyl esters include vinyl acetate and vinyl propionate.

Examples of the vinyl alkyl ethers include methyl vinyl ether and ethyl vinyl ether.

Examples of the aromatic hydrocarbon group-containing monomer include aromatic vinyl compounds and (meth)acrylic acid esters having an aromatic hydrocarbon group.

Examples of the aromatic vinyl compound include styrene, α-methylstyrene, vinyltoluene, and the like.

Examples of (meth)acrylic acid esters having an aromatic hydrocarbon group include phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate.

Examples of the olefins or dienes include ethylene, butadiene, isoprene, and isobutylene.

In addition to these, the copolymerizable monomers include heterocyclic ring-containing (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate, halogen atom-containing (meth)acrylates such as vinyl chloride and fluorine atom-containing (meth)acrylates, A (meth)acrylic acid ester obtained from a terpene compound derivative alcohol may also be included.

Each of the copolymerizable monomers may be used alone or in combination of two or more.

The content of units derived from copolymerizable monomers other than the nitrogen atom-containing monomer and the hydroxyl group-containing monomer in the acrylic polymer is preferably 10.0% by weight or less with respect to 100% by weight of all monomer-derived units. , more preferably 5.0% by weight or less, and still more preferably 3.0% by weight or less. The lower limit may be, for example, 0% by weight.

In addition to the units derived from the monomers constituting the acrylic polymer, the acrylic polymer includes, for example, a polymerization initiator, a cross-linking agent, a polyfunctional monomer, a silane coupling agent, a solvent, Tackifying resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenols, etc.), antioxidants, fillers, UV absorbers, antioxidants, chain transfer agents, plasticizers, softeners, surfactants, antistatic Additives such as agents and antirust agents may be added. These additives may be used alone or in combination of two or more.

Examples of the polymerization initiator include photopolymerization initiators (photoinitiators) and thermal polymerization initiators. Only one kind of the polymerization initiator may be used, or two or more kinds thereof may be used. In addition, since the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition has sufficient shape stability, it does not necessarily contain a polymerization initiator.

Examples of the photopolymerization initiator include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, and photoactive oxime-based photopolymerization initiators. Examples include initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, and the like.

Examples of the benzoin ether-based photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethan-1-one, anisole methyl ether and the like.

Examples of the acetophenone-based photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenylketone, 4-phenoxydichloroacetophenone, 4-(t-butyl ) and dichloroacetophenone.

Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one, and the like. be done.

Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride.

Examples of the photoactive oxime-based photopolymerization initiator include 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime.

Examples of the benzoin-based photopolymerization initiator include benzoin.

Examples of the benzyl-based photopolymerization initiator include benzyl.

Examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexylphenyl ketone, and the like.

Examples of the ketal-based photopolymerization initiator include benzyl dimethyl ketal.

Examples of the thioxanthone-based photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone.

The amount used when using the photopolymerization initiator is not particularly limited, but is preferably 0.01 to 1.0 parts by weight, more preferably 0.04 to 0.04 parts by weight, relative to 100 parts by weight of the acrylic polymer. .5 parts by weight.

Examples of the thermal polymerization initiator include azo polymerization initiators, peroxide polymerization initiators (dibenzoyl peroxide, tert-butyl permaleate, etc.), redox polymerization initiators, and the like. Among them, an azo polymerization initiator is preferable.

Examples of the azo polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, 2,2′-azobis(2-methylpropionate)dimethyl, 4,4'-azobis-4-cyanovaleric acid and the like.

When the azo polymerization initiator is used, the amount used is not particularly limited, but is preferably 0.01 to 0.5 parts by weight, more preferably 0.04 to 0.04 parts by weight, relative to 100 parts by weight of the acrylic polymer. 0.3 parts by weight.

The cross-linking agent can be blended for the purpose of cross-linking within the pressure-sensitive adhesive layer or cross-linking between the pressure-sensitive adhesive layer and its adjacent surface. Specific examples include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, carbodiimide-based cross-linking agents, melamine-based cross-linking agents, urea-based cross-linking agents, metal alkoxide-based cross-linking agents, and metal chelates. cross-linking agents, metal salt-based cross-linking agents, hydrazine-based cross-linking agents, amine-based cross-linking agents, and the like. These may use only 1 type and may use 2 or more types.

The isocyanate-based cross-linking agent is preferably a compound having two or more isocyanate groups in one molecule. (p-isocyanatophenyl) thiophosphate, diphenylmethane diisocyanate, etc.), alicyclic isocyanate (isophorone diisocyanate, etc.), aliphatic isocyanate (hexamethylene diisocyanate, etc.), and the like.

The epoxy-based cross-linking agent is preferably a compound having two or more (preferably 3 to 5) epoxy groups in one molecule. -tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, polyglycerol polyglycidyl ether and the like. be done.

The oxazoline-based cross-linking agent is preferably a compound having one or more oxazoline groups in one molecule.

Examples of the aziridine-based cross-linking agent include trimethylolpropane tris [3-(1-aziridinyl) propionate], trimethylol propane tris [3-(1-(2-methyl) aziridinyl propionate)], and the like. mentioned.

The carbodiimide-based cross-linking agent is preferably a low-molecular-weight compound or a high-molecular-weight compound having two or more carbodiimide groups.

The content of the cross-linking agent is preferably 1.5 parts by weight or less, more preferably 0.001 to 1 part by weight, based on 100 parts by weight of the acrylic polymer, in order to easily achieve a good balance of adhesive strength and cohesive strength. 0.5 parts by weight, more preferably 0.005 to 1.0 parts by weight, particularly preferably 0.010 to 0.5 parts by weight.

The polyfunctional monomer can be blended for the purpose of adjusting the cohesive force in place of the cross-linking agent or in combination with the cross-linking agent. Specific examples include ethylene glycol di(meth)acrylate, Propylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, di Pentaerythritol hexa(meth)acrylate, ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetra Methylolmethane tri(meth)acrylate, allyl(meth)acrylate, vinyl(meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyldiol (meth)acrylate, hexyldiol di(meth)acrylate, etc. . These may use only 1 type and may use 2 or more types.

The content of the polyfunctional monomer is preferably 1.5 parts by weight or less, more preferably 1.0 parts by weight or less, and still more preferably 0.5 parts by weight or less with respect to 100 parts by weight of the acrylic polymer. be. The lower limit may be 0 parts by weight, 0.001 parts by weight, 0.005 parts by weight, or 0.010 parts by weight. When the content of the polyfunctional monomer is within the above range, it becomes easier to achieve well-balanced adhesive strength and cohesive strength.

Examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-phenyl-aminopropyltrimethoxysilane, and the like. be done. Among them, γ-glycidoxypropyltrimethoxysilane is preferred. Only one kind of the silane coupling agent may be used, or two or more kinds thereof may be used.

The content of the silane coupling agent in the pressure-sensitive adhesive composition is preferably 0.50 parts by weight or less, more preferably 0.50 parts by weight with respect to 100 parts by weight of the acrylic polymer, from the viewpoint of obtaining adhesion reliability to glass. 30 parts by weight or less, more preferably 0.27 parts by weight or less. The lower limit may be 0 parts by weight, and may be 0.01 parts by weight or 0.03 parts by weight.

Examples of the solvent include esters (ethyl acetate, n-butyl acetate, etc.), aromatic hydrocarbons (toluene, benzene, etc.), aliphatic hydrocarbons (n-hexane, n-heptane, etc.), alicyclic Examples include organic solvents such as hydrocarbons of formula (cyclohexane, methylcyclohexane, etc.), ketones (methylethylketone, methylisobutylketone, etc.). Only one kind of the solvent may be used, or two or more kinds thereof may be used.

The total content of the above additives is preferably 10.0% by weight or less, more preferably 5.0% by weight or less, still more preferably 5.0% by weight or less, from the viewpoint of ensuring sufficient transparency of the optical pressure-sensitive adhesive sheet of the present invention. is 3.0% by weight or less, particularly preferably 1.0% by weight or less.

The pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer according to the present invention can be, for example, a mixture of monomer components, a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, or a polymerization method by irradiation with an active energy ray (active energy ray Polymerization method) or the like can be prepared by adding an additive to a polymer or partial polymer obtained by polymerization, if necessary.

The pressure-sensitive adhesive layer is formed, for example, by applying (coating) the pressure-sensitive adhesive composition onto a substrate or a release liner and drying and curing it, or by applying (coating) the pressure-sensitive adhesive composition onto a substrate or a release liner. ) and curing by irradiating with active energy rays (ionizing radiation such as α-rays, β-rays, γ-rays, neutron beams and electron beams, ultraviolet rays, etc.).

The application (coating) is performed by a known coating method using a coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater, and a direct coater. It can be carried out.

The optical pressure-sensitive adhesive sheet of the present invention is produced by forming a pressure-sensitive adhesive layer on a release liner in the case of a substrate-less pressure-sensitive adhesive sheet, or directly on the surface of a substrate in the case of a substrate-attached pressure-sensitive adhesive sheet. It can be produced by forming (direct transfer method), or by forming an adhesive layer (transfer method) by forming an adhesive layer on a release liner and then laminating it to a base material.

Although the thickness of the optical pressure-sensitive adhesive sheet of the present invention is not particularly limited, it is preferably 90 µm or more, more preferably 95 µm or more, and still more preferably 100 µm or more. Also, the thickness is preferably 300 μm or less, more preferably 270 μm or less, and still more preferably 230 μm or less. The thickness of the optical pressure-sensitive adhesive sheet of the present invention does not include the thickness of the release liner.

The total light transmittance of the optical pressure-sensitive adhesive sheet of the present invention measured according to JIS K7136 is not particularly limited, but is preferably 85.0% or more, more preferably 90.0, from the viewpoint of appearance characteristics and transparency. % or more, more preferably 92.0% or more.

The haze of the optical pressure-sensitive adhesive sheet of the present invention measured according to JIS K7136 is preferably 1.0% or less, more preferably 0.5% or less, from the viewpoint of appearance properties and transparency.

The optical pressure-sensitive adhesive sheet of the present invention is suitably used for bonding a polarizing plate containing iodine and an optical sensor having a silver nanowire layer in an image display device. When the polarizing plate and the optical sensor are bonded together, the adhesive surface of the adhesive layer according to the present invention may be directly attached to the polarizing plate and the silver nanowire layer, or the polarizing plate and the silver nanowire layer are protected. It may be attached to a protective layer made of resin. Examples of the silver nanowire layer include a layer in which fine metal wires containing silver are mesh-printed, a film (silver nanowire film) formed of fine metal wires (nanowires) containing silver, and the like.

The optical pressure-sensitive adhesive sheet of the present invention includes, for example, image display panels (liquid crystal display panels, plasma display panels, etc.), wave plates, retardation plates, optical compensation films, brightness enhancement films, light guide plates, reflective films, antireflection films, Hard-coated film (a plastic film such as polyethylene terephthalate film that has been hard-coated on at least one side), transparent conductive film, design film, decorative film, surface protection plate, prism, lens, color filter, transparent substrate (glass) Sensors, glass display panels (LCD, etc.), glass substrates such as glass plates with transparent electrodes, etc.), and optical members such as touch sensors having an ITO (indium tin oxide) layer or a zinc oxide (ZnO) layer. may be used.

As described above, the image display device of the present invention includes at least a polarizing plate containing iodine, an optical pressure-sensitive adhesive sheet of the present invention, and an optical sensor having a silver nanowire layer. and the optical sensor in this order.

EXAMPLES The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

<Production Example 1: Production of polarizing plate>
A laminate consisting of a polyvinyl alcohol layer having a thickness of 9 μm and an amorphous polyethylene terephthalate film as a base material was uniaxially stretched by air auxiliary stretching at 130° C. to obtain a stretched laminate.

Next, the stretched laminate is placed in a dyeing bath (iodine aqueous solution containing iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water) at a liquid temperature of 30 ° C. The finally obtained polarizer A colored laminate was obtained by immersing while adjusting the concentration so that the transmittance of the single layer was 43.0% or more.

Next, the colored laminate is insolubilized in an insolubilizing bath (an aqueous boric acid solution containing 4 parts by weight of boric acid per 100 parts by weight of water) at a liquid temperature of 65° C., and the total draw ratio is 5.94 times. An optical film laminate having a polarizer (thickness 5 μm) in which iodine adsorbed to the polyvinyl alcohol layer by dyeing is highly oriented in one direction as a polyiodine ion complex was obtained.

A polyvinyl alcohol adhesive was applied to the surface of the optical film laminate on the polarizer side to a thickness of 1.0 μm, and an acrylic film (thickness: 20 μm) was used as a transparent protective film using a roll machine. After drying at 50° C. for 5 minutes, the substrate polyethylene terephthalate film was peeled off to obtain a polarizing plate with one side protection.

A monomer mixture composed of 99.0 parts by weight of tert-butyl acrylate (BA) and 1.0 parts by weight of 4-hydroxybutyl acrylate (4HBA) was added with 0.2 parts by weight of azobisisobutylnitrile and ethyl acetate. was put into a four-necked flask so that the solid content was 20% by weight, and heated at 60° C. for 7 hours in a nitrogen atmosphere to obtain an acrylic polymer having a polymerization average molecular weight of 1,100,000. Per 100 parts by weight of the solid content of this acrylic polymer, 0.8 parts by weight of trimethylolpropane tolylene diisocyanate (trade name "Coronate L", manufactured by Nippon Polyurethane Industry Co., Ltd.), a silane coupling agent (3-glycan 0.1 part by weight of sidoxypropyltrimethoxysilane (trade name: "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) was added and uniformly mixed to obtain an adhesive composition. The obtained adhesive composition was applied onto a polyethylene terephthalate-based release liner (thickness: 38 μm) and dried by heating at 60° C. for 1 minute and at 150° C. for 1 minute under normal pressure to form an adhesive layer (thickness: 20 μm). got

The resulting pressure-sensitive adhesive layer (thickness 20 μm) is transferred to the polarizer side of the single-sided protective polarizing film to form a polarizing film with a pressure-sensitive adhesive layer (release liner/adhesive layer/polarizer/transparent protective film). Obtained.

<Production Example 2: Production of transparent conductive film>
5 ml of anhydrous ethylene glycol and 0.5 ml of anhydrous ethylene glycol solution of PtCl ₂ (1.5×10 ⁻⁴ mol/l) were added to a reactor equipped with a stirrer and heated at 160° C. for 4 minutes to form a solution. After that, 2.5 ml of an anhydrous ethylene glycol solution (0.12 mol/l) of AgNO ₃ and 5 ml of an anhydrous ethylene glycol solution (0.36 mol/l) of polyvinylpyrrolidone (Mw 55000) were simultaneously added dropwise over 6 minutes. After the dropwise addition, reaction was carried out at 160° C. until AgNO ₃ was completely reduced to obtain a reaction mixture containing crude silver nanowires. Then, acetone was added to the reaction mixture so that the volume ratio was 5 times, and the mixture was centrifuged (2000 rpm, 20 minutes) to obtain silver nanowires. The obtained silver nanowires had a wire minor diameter of 30 nm to 40 nm, a wire major diameter of 30 nm to 50 nm, and a wire length of 30 μm to 50 μm.

Next, 0.2 parts by weight of silver nanowires and 0.1 parts by weight of pentaethylene glycol dodecyl ether were mixed with 100 parts by weight of pure water to obtain a silver nanowire dispersion.

In addition, a mixed solvent (a mixture of isopropyl alcohol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and diacetone alcohol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) at a weight ratio of 1:1) was added to 100 parts by weight. On the other hand, dipentaerythritol hexaacrylate (trade name "NK Ester A-DPH", manufactured by Shin Nakamura Chemical Co., Ltd.) 3.0 parts by weight, photopolymerization initiator (trade name "Irgacure 907", BASF Japan Co., Ltd. ) was added to prepare a composition for forming a protective layer.

Transparent substrate (norbornene-cyclohexane type cyclic olefin film (trade name “Zeonor”, manufactured by Nippon Zeon Co., Ltd., in-plane retardation Re: 1.7 nm, thickness direction retardation Rth: 1.8 nm), silver A silver nanowire layer was formed by applying the nanowire dispersion liquid and drying for 2 minutes at 120° C. After that, a composition for forming a protective layer was further applied to the silver nanowire layer side and dried for 2 minutes at 120° C. Then, UV irradiation (accumulated illuminance: 400 mJ/cm ² ) was performed under an oxygen concentration of 100 ppm to cure and form a protective layer to obtain a transparent conductive film (transparent substrate/silver nanowire layer/protective layer). The transparent conductive film had a surface resistance of 50Ω/□, a total light transmittance of 91.4%, and a haze of 2.0%.

<Production of acrylic pressure-sensitive adhesive sheet>

(Example 1)
2-ethylhexyl acrylate (2EHA) 36.8 parts by weight, isostearyl acrylate (ISTA) 36.8 parts by weight, 4-hydroxybutyl acrylate (4HBA) 0.9 parts by weight, N-vinyl-2-pyrrolidone ( NVP) to a monomer mixture composed of 25.5 parts by weight, 1-hydroxy-cyclohexyl-phenyl-ketone (trade name "Irgacure 184", manufactured by BASF Japan Co., Ltd.) 0.045 parts by weight, and 2,2 -Dimethoxy-1,2-diphenyl-1-one (trade name "Irgacure 651", manufactured by BASF Japan Co., Ltd.) 0.045 parts by weight was charged into a four-necked flask and exposed to ultraviolet rays in a nitrogen atmosphere. A partially polymerized product having a degree of polymerization of about 10% was obtained by partially photopolymerizing the polymer. To 100 parts by weight of this partial polymer, 0.018 parts by weight of trimethylolpropane triacrylate (trade name "TMP3A", manufactured by Osaka Organic Chemical Industry Co., Ltd.), a silane coupling agent (3-glycidoxypropyltrimethoxysilane , trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) was added and uniformly mixed to obtain an acrylic pressure-sensitive adhesive composition.

The acrylic pressure-sensitive adhesive composition was applied onto a polyethylene terephthalate (PET) release liner (manufactured by Nitto Denko Corporation, thickness: 125 μm) to form a pressure-sensitive adhesive composition layer. Next, a PET release liner (manufactured by Nitto Denko Corporation, thickness: 125 μm) was provided on the pressure-sensitive adhesive composition layer to cover the pressure-sensitive adhesive composition layer and block oxygen. Then, a laminate (laminate (I)) having a configuration of [release liner/adhesive composition layer/release liner] was obtained. Next, the layered product (I) is irradiated with ultraviolet light having an illuminance of 3 mW/cm ² for 300 seconds from the upper surface (release liner side) of the layered product (I) using a black light (manufactured by Toshiba Corporation). A double-sided PSA sheet (substrate-less PSA sheet) having a structure of [release liner/adhesive layer/release liner] and having both sides of the adhesive surface protected by a release liner was prepared. The thickness of the double-sided pressure-sensitive adhesive sheet (thickness excluding the release liner) was 100 µm.

(Example 2)
2-ethylhexyl acrylate (2EHA) 33.8 parts by weight, isostearyl acrylate (ISTA) 33.8 parts by weight, 4-hydroxybutyl acrylate (4HBA) 0.8 parts by weight, N-vinyl-2-pyrrolidone ( NVP) to a monomer mixture composed of 31.6 parts by weight, 1-hydroxy-cyclohexyl-phenyl-ketone (trade name "Irgacure 184", manufactured by BASF Japan Co., Ltd.) 0.042 parts by weight, and 2,2 -Dimethoxy-1,2-diphenyl-1-one (trade name "Irgacure 651", manufactured by BASF Japan Co., Ltd.) 0.042 parts by weight was charged into a four-necked flask and exposed to ultraviolet rays in a nitrogen atmosphere. A partially polymerized product having a degree of polymerization of about 10% was obtained by partially photopolymerizing the polymer. To 100 parts by weight of this partially polymerized product, 0.017 parts by weight of trimethylolpropane triacrylate (trade name "TMP3A", manufactured by Osaka Organic Chemical Industry Co., Ltd.), a silane coupling agent (3-glycidoxypropyltrimethoxysilane , trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) was added and uniformly mixed to obtain an acrylic pressure-sensitive adhesive composition. A pressure-sensitive adhesive sheet (thickness 100 μm excluding the release liner) was produced in the same manner as in Example 1 from the obtained acrylic pressure-sensitive adhesive composition.

(Example 3)
A pressure-sensitive adhesive sheet (thickness 100 μm excluding the release liner) was prepared in the same manner as in Example 1, except that 0.015 parts by weight of trimethylolpropane triacrylate (trade name “TMP3A”, manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used. was made.

(Example 4)
A pressure-sensitive adhesive sheet (excluding the release liner) was prepared in the same manner as in Example 3, except that 0.013 parts by weight of trimethylolpropane triacrylate (TMPTA) (trade name "TMP3A", manufactured by Osaka Organic Chemical Industry Co., Ltd.) was used. thickness of 100 μm).

(Comparative example 1)
40.5 parts by weight of 2-ethylhexyl acrylate (2EHA), 40.5 parts by weight of isostearyl acrylate (ISTA), 1.0 parts by weight of 4-hydroxybutyl acrylate (4HBA), N-vinyl-2-pyrrolidone ( NVP) to a monomer mixture composed of 18.0 parts by weight, 1-hydroxy-cyclohexyl-phenyl-ketone (trade name "Irgacure 184", manufactured by BASF Japan Co., Ltd.) 0.050 parts by weight, and 2,2 -Dimethoxy-1,2-diphenyl-1-one (trade name "Irgacure 651", manufactured by BASF Japan Co., Ltd.) 0.050 parts by weight was put into a four-necked flask and exposed to ultraviolet rays in a nitrogen atmosphere. A partially polymerized product having a degree of polymerization of about 10% was obtained by partially photopolymerizing the polymer. To 100 parts by weight of this partially polymerized product, 0.150 parts by weight of trimethylolpropane triacrylate (trade name "TMP3A", manufactured by Osaka Organic Chemical Industry Co., Ltd.), a silane coupling agent (3-glycidoxypropyltrimethoxysilane , trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) 0.30 parts by weight, 0.15 parts by weight of 1-thioglycerol as a chain transfer agent are added, mixed uniformly, and acrylic adhesive An agent composition was obtained. A pressure-sensitive adhesive sheet (thickness 100 μm excluding the release liner) was produced in the same manner as in Example 1 from the obtained acrylic pressure-sensitive adhesive composition.

(Comparative example 2)
Monomer mixture composed of 81.0 parts by weight of 2-ethylhexyl acrylate (2EHA), 4.8 parts by weight of 2-hydroxyethyl acrylate (HEA), and 14.2 parts by weight of N-vinyl-2-pyrrolidone (NVP) In addition, 1-hydroxy-cyclohexyl-phenyl-ketone (trade name “Irgacure 184”, manufactured by BASF Japan Ltd.) 0.048 parts by weight, and 2,2-dimethoxy-1,2-diphenyl-1-one ( The product name "Irgacure 651", manufactured by BASF Japan Co., Ltd.) 0.048 parts by weight is put into a four-necked flask and partially photopolymerized by exposing it to ultraviolet rays in a nitrogen atmosphere. About 10% partial polymer was obtained. To 100 parts by weight of this partial polymer, 0.084 parts by weight of 1,6-hexanediol diacrylate (trade name "NK Ester A-HD-N", manufactured by Shin-Nakamura Chemical Co., Ltd.), a silane coupling agent ( 0.34 parts by weight of 3-glycidoxypropyltrimethoxysilane, trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) was added and uniformly mixed to obtain an acrylic pressure-sensitive adhesive composition. rice field. A pressure-sensitive adhesive sheet (thickness 100 μm excluding the release liner) was produced in the same manner as in Example 1 from the obtained acrylic pressure-sensitive adhesive composition.

(Comparative Example 3)
A monomer mixture composed of 70.0 parts by weight of n-butyl acrylate (BA), 20.0 parts by weight of 4-hydroxybutyl acrylate (4HBA), and 10.0 parts by weight of 2-hydroxyethyl acrylate (HEA) , 1-hydroxy-cyclohexyl-phenyl-ketone (trade name “Irgacure 184”, manufactured by BASF Japan Ltd.) 0.050 parts by weight, and 2,2-dimethoxy-1,2-diphenyl-1-one (trade name The name "Irgacure 651", manufactured by BASF Japan Co., Ltd.) 0.050 parts by weight is put into a four-necked flask and partially photopolymerized by exposing it to ultraviolet rays in a nitrogen atmosphere. A partial polymer of 10% was obtained. To 100 parts by weight of this partial polymer, 0.120 parts by weight of dipentaerythritol hexaacrylate (DPHA), a silane coupling agent (3-glycidoxypropyltrimethoxysilane, trade name "KBM-403", Shin-Etsu Chemical Co., Ltd. ( 0.35 parts by weight (manufactured by Co., Ltd.) was added and uniformly mixed to obtain an acrylic pressure-sensitive adhesive composition. A pressure-sensitive adhesive sheet (thickness 100 μm excluding the release liner) was produced in the same manner as in Example 1 from the obtained acrylic pressure-sensitive adhesive composition.

(Comparative Example 4)
2-ethylhexyl acrylate (2EHA) 30.0 parts by weight, isostearyl acrylate (ISTA) 30.0 parts by weight, isobornyl acrylate (IBXA) 20.0 parts by weight, 4-hydroxybutyl acrylate (4HBA) 20. A monomer mixture composed of 0 parts by weight, 1-hydroxy-cyclohexyl-phenyl-ketone (trade name "Irgacure 184", manufactured by BASF Japan Co., Ltd.) 0.050 parts by weight, and 2,2-dimethoxy-1 , 2-diphenyl-1-one (trade name “Irgacure 651”, manufactured by BASF Japan Co., Ltd.) 0.050 parts by weight was charged into a four-necked flask and partially exposed to ultraviolet light in a nitrogen atmosphere. By photopolymerization, a partial polymer having a polymerization rate of about 10% was obtained. To 100 parts by weight of this partial polymer, 0.090 parts by weight of 1,6-hexanediol diacrylate (trade name "NK Ester A-HD-N", manufactured by Shin-Nakamura Chemical Co., Ltd.), a silane coupling agent ( 0.30 parts by weight of 3-glycidoxypropyltrimethoxysilane, trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) was added and uniformly mixed to obtain an acrylic pressure-sensitive adhesive composition. rice field. A pressure-sensitive adhesive sheet (thickness 100 μm excluding the release liner) was produced in the same manner as in Example 1 from the obtained acrylic pressure-sensitive adhesive composition.

<Evaluation>
The pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were evaluated as follows.

(1) Amount of iodine ions eluted

(Preparation of test piece)
A polarizing plate (9 cm ² (3 cm × 3 cm, regular square)) from which the release liner was peeled off was placed on a glass plate (5 cm × 4.5 cm, thickness 1.2 to 1.5 mm, trade name “MICRO SLIDE GLASS S200200”, (manufactured by Matsunami Glass Industry Co., Ltd.) to prepare a test piece of "a polarizing plate attached to a glass plate".

Also, the pressure-sensitive adhesive sheets of Examples and Comparative Examples (16 cm ² (4 cm × 4 cm, regular square)) were attached with one adhesive surface so as to completely cover the polarizing plate of the test piece, and then the release liner was peeled off. A test piece of "a polarizing plate attached to a glass plate and further covered with the pressure-sensitive adhesive layer" was prepared.

(Elution of iodine ions)
Next, the test piece of the "polarizing plate attached to the glass plate" and the test piece of the "polarizing plate attached to the glass plate and further covered with the pressure-sensitive adhesive layer" are placed in a sealed container. immersed in 150 ml of ultrapure water at a temperature of 85° C. and heated for 24 hours to elute iodide ions.

Then, the amount (ppm) of iodide ions was measured for each eluate obtained by ion chromatography.

The value of the amount of iodide ions (iodine ion elution amount I ₀ : 2.1 ppm) obtained for the test piece of the above-mentioned "polarizing plate attached to a glass plate" indicates that the amount of iodine ions is "attached to a glass plate and further The weight ratio (I/I ₀ ) was calculated by dividing the value of the amount of iodide ions (iodine ion elution amount I) obtained for the test piece of "covered polarizing plate". Table 1 shows the results.

The measurement conditions for the ion chromatography method (ion chromatography) were as follows.

(Measurement conditions for ion chromatography)
Analyzer: Thermo Fisher Scientific, ICS-3000
Separation column: Dionex Ion Pac AS20 (2 mm x 250 mm)
Guard column: Dionex Ion Pac AG20 (2mm x 50mm)
Removal system: AERS-500 (external mode)
Detector: Electrical conductivity detector Eluent: KOH aqueous solution Eluent flow rate: 0.25 ml/min
Sample injection volume: 25 μl

(2) Corrosion of silver nanowire layer

(Preparation of test piece)
A polarizing plate (3 cm × 3 cm, regular square) from which the release liner was peeled off was prepared by a glass plate (5 cm × 4.5 cm, thickness 1.2 to 1.5 mm, trade name “MICRO SLIDE GLASS S200200”, Matsunami Glass Industry ( Co., Ltd.), and then the adhesive sheets of Examples and Comparative Examples (4 cm × 4 cm, square) were attached with one adhesive surface so as to completely cover the polarizing plate, and then the release liner was peeled off. A test piece was prepared by further bonding a transparent conductive film (4 cm×4.5 cm, strip-shaped) to the adhesive surface on the surface on the protective layer side.

(Evaluation of corrosion)
Next, the degree of corrosion of the silver nanowire layer was evaluated by visually observing the state after the test piece was stored in an environment of 65° C. and 90% Rh for 100 hours.

(Evaluation criteria for corrosion)
○ (good): neither corrosion nor discoloration △ (slightly poor): no corrosion but discoloration (yellow) × (bad): corrosion

(3) Moisture Permeability Measurement samples obtained by cutting out the pressure-sensitive adhesive sheets of Examples and Comparative Examples into circular shapes of 10 cmΦ and peeling off the release liner were measured using a water vapor transmission rate measuring device (product name “DELTAPERM”, manufactured by Technolox). The moisture permeability was measured under test conditions of 40° C. and 90% RH according to the moisture permeability test (cup method) of JIS Z0208.

(4) Total light transmittance, haze The pressure-sensitive adhesive sheets of Examples and Comparative Examples were placed on a slide glass (thickness: 0.8 to 1.0 mm, total light transmittance: 92%, haze: 0.2%, product name: "White polishing No. 1", manufactured by Matsunami Glass Industry Co., Ltd.), the total light transmittance and haze value in the visible light region were measured using a haze meter (product name "HM-150" ) made by Murakami Color Laboratory).

(5) Transparency stability The pressure-sensitive adhesive sheets of Examples and Comparative Examples were placed on a slide glass (thickness: 0.8 to 1.0 mm, total light transmittance: 92%, haze: 0.2%, trade name: "White polishing No. 1"). , manufactured by Matsunami Glass Industry Co., Ltd.), and the release liner was peeled off, and the measurement sample was stored in hot water at 85 ° C. for 24 hours. evaluated.

(Evaluation criteria for transparency stability)
○ (Good): Neither cloudiness nor discoloration × (Bad): There was cloudiness and / or discoloration (yellow)

The adhesive sheets of Examples 1 to 4 had a weight ratio (I/I ₀ ) of 0.015 to 0.018, a moisture permeability of 171 to 183 g/(m ² ·24 h), and a value (X × Y/100) of 25.4 to 31.5, the value (X × Y / Z) is 13.9 to 18.4, all within the scope of the present invention, and the corrosion of the silver nanowire layer is a good result of ◯ showed that. Moreover, the pressure-sensitive adhesive sheets of Examples 1 to 4 exhibited excellent optical properties such as a total light transmittance of 92.0%, a haze of 0.2%, and a transparency stability of ◯.

On the other hand, at least one of the weight ratio (I/I ₀ ), the moisture permeability, the value (X×Y/100), and the value (X×Y/Z) is outside the scope of the present invention. The adhesive sheets of ~4 showed inferior results of Δ or × for corrosion of the silver nanowire layer.

1 Image display device 2a Adhesive layer 2b Adhesive layer 3 Polarizing plate 4 Silver nanowire layer 5 Substrate 6 Optical sensor 7 Image display panel 8 Cover

Claims (7)

An optical pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer in which the weight ratio (I/ _{I 0 )} of I below to I 0 below is 0.05 or less.
I ₀ : Iodine ion elution amount (ppm) when a 9 cm ² polarizing plate attached to a glass plate was immersed in 150 ml of water at 85° C. and stored for 24 hours.
I: Iodine ion elution amount (ppm) when a 9 cm ² polarizing plate attached to a glass plate and covered with the adhesive layer having a thickness of 100 μm was immersed in 150 ml of water at 85° C. for 24 hours. The optical pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive layer contains, as a base polymer, an acrylic polymer having a unit derived from a nitrogen atom-containing monomer. In the pressure-sensitive adhesive layer, the thickness X (μm) of the pressure-sensitive adhesive layer and the content ratio Y (% by weight) of the unit derived from the nitrogen atom-containing monomer in the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer are as follows. 3. The optical pressure-sensitive adhesive sheet according to claim 2, which satisfies formula (1).
20.0≦(X×Y/100)≦120.0 (1) The optical layer according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive layer has a moisture permeability of 500 g/(m ² ·24 h) or less at 40°C and 92% RH when the thickness is 100 µm. adhesive sheet. In the pressure-sensitive adhesive layer, the thickness X (μm), the content ratio Y (% by weight), and the moisture permeability Z (g/(m ² 24 h)) are expressed by the following formula (2) The optical pressure-sensitive adhesive sheet according to claim 4, which satisfies:
10.0≦(X×Y/Z)≦120.0 (2) The optical pressure-sensitive adhesive sheet according to any one of claims 2 to 5, wherein the acrylic polymer has a group containing a linear or branched alkyl group having 8 to 18 carbon atoms in a side chain. An image display device comprising a polarizing plate, an optical pressure-sensitive adhesive sheet according to any one of claims 1 to 6, and an optical sensor in this order.

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