Optical adhesive sheet

Abstract

To provide an adhesive sheet for an optical use excellent in anticorrosiveness to a silver nanowire layer.SOLUTION: An adhesive sheet for an optical use includes an adhesive layer in which a weight ratio (I / I0) of a following I to a following I0 is 0.05 or less: the I0 being an iodine ion elution (ppm) when a 9 cm2 polarizer adhered onto a glass plate is immersed in 150 ml of water at 85°C and stored for 24 hours, and the I being an iodine ion elution (ppm) when a 9 cm2 polarizer adhered onto a glass plate and covered with the adhesive layer of 100 μm thick is immersed in 150 ml of water at 85°C and stored for 24 hours.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical pressure-sensitive adhesive sheet. [Background technology]

[0002] BACKGROUND ART Conventionally, transparent optical pressure-sensitive adhesive sheets having a pressure-sensitive adhesive layer have 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).

[0003] On the other hand, iodine-containing polyvinyl alcohol sheets are often used as polarizing plates on the surfaces of image display devices such as liquid crystal display devices and organic EL display devices because they have the advantage of combining high transmittance with high polarization degree, and transparent optical adhesive sheets having an adhesive layer are also used to bond polarizing plates to sensor films. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-238915 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-342542 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-231723 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, optical sensors having a silver nanowire layer as a sensor film have been widely used, and because the silver nanowire layer is susceptible to corrosion, there is a demand for optical adhesive sheets that can suppress corrosion of the silver nanowire layer.

[0006] Therefore, an object of the present invention is to provide an optical adhesive sheet that effectively suppresses corrosion of the silver nanowire layer of an optical sensor. [Means for solving the problem]

[0007] As a result of intensive research to achieve the above-mentioned objective, the inventors discovered that corrosion of the silver nanowire layer of an optical sensor can be effectively suppressed by limiting the amount of iodine ion transmission through an optical adhesive sheet to a specific amount or less, and thus completed the present invention.

[0008] That is, the present invention provides an optical pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer in which the weight ratio (I / I0) of the following I to the following I0 is 0.05 or less. I0: 9cm attached to glass plate 2 The amount of iodine ions eluted (ppm) when the polarizing plate was immersed in 150 ml of water at 85°C and stored for 24 hours. I: 9 cm2 adhesive layer attached to a glass plate and covered with the above adhesive layer of 100 μm thickness 2 The amount of iodine ions eluted (ppm) when the polarizing plate was immersed in 150 ml of water at 85°C and stored for 24 hours.

[0009] The pressure-sensitive adhesive layer preferably contains, as a base polymer, an acrylic polymer having a unit derived from a nitrogen atom-containing monomer.

[0010] In the pressure-sensitive adhesive layer, it is preferable that the thickness X (μm) of the pressure-sensitive adhesive layer and the content Y (wt %) of units derived from nitrogen-atom-containing monomers in the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer satisfy the following formula (1): 20.0≦(X×Y / 100)≦120.0 (1)

[0011] The pressure-sensitive adhesive layer has a moisture permeability of 500 g / (m) at 40°C and 92% RH when the thickness is 100 μm. 2 24 hours or less is preferable.

[0012] In the pressure-sensitive adhesive layer, the thickness X (μm), the content Y (wt %), and the moisture permeability Z (g / (m 2 ·24h)) preferably satisfies the following formula (2). 10.0≦(X×Y / Z)≦120.0 (2)

[0013] The acrylic polymer preferably has a group containing a linear or branched alkyl group having 8 to 18 carbon atoms in the side chain.

[0014] The present invention also provides an image display device including a polarizing plate, the optical pressure-sensitive adhesive sheet, and an optical sensor in this order. [Effects of the Invention]

[0015] The optical adhesive sheet of the present invention can effectively suppress corrosion of the silver nanowire layer of an optical sensor bonded to a polarizing plate by iodine ions, and can therefore be suitably used for bonding a polarizing plate to an optical sensor. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of an image display device in which the optical pressure-sensitive adhesive sheet of the present invention is used. DETAILED DESCRIPTION OF THE INVENTION

[0017] As shown in Figure 1, the optical pressure-sensitive adhesive sheet of the present invention is suitably used as a pressure-sensitive adhesive layer 2a that bonds a polarizing plate 3 and an optical sensor 6, effectively suppressing the transmission of iodine ions leaching from the polarizing plate 3 and suppressing corrosion of the silver nanowire layer 4 by iodine ions. The optical pressure-sensitive adhesive sheet of the present invention also has the effect of suppressing the transmission of moisture and suppressing the release and leaching of iodine ions in the polarizing plate, and therefore can also be used as a pressure-sensitive adhesive layer (not shown) that bonds the polarizing plate 3 and the cover 8. The optical pressure-sensitive adhesive sheet of the present invention can also be used as a pressure-sensitive adhesive layer 2b that bonds, for example, the optical sensor 6 and the image display panel 7.

[0018] 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 (I / I0) of the following I to the following I0 is 0.05 or less. I0: 9cm attached to glass plate 2 The amount of iodine ions eluted (ppm) when the polarizing plate was immersed in 150 ml of water at 85°C and stored for 24 hours. I: 9 cm2 adhesive layer attached to a glass plate and covered with the above adhesive layer of 100 μm thickness 2 The amount of iodine ions eluted (ppm) when the polarizing plate was immersed in 150 ml of water at 85°C and stored for 24 hours.

[0019] The configuration in which the weight ratio (I / I0) is 0.05 or less is advantageous in that it can effectively suppress corrosion of the silver nanowire layer by iodine ions in an optical sensor attached to a polarizing plate using the optical adhesive sheet of the present invention.

[0020] The weight ratio (I / I0) is 0.05 or less, preferably 0.04 or less, more preferably 0.03 or less, and even more preferably 0.02 or less. The lower limit is not particularly limited, but is preferably 0.005. When the weight ratio (I / I0) is 0.05 or less, corrosion of the silver nanowire layer is less likely to occur in an optical sensor attached to a polarizing plate via the optical pressure-sensitive adhesive sheet of the present invention. The weight ratio (I / I0) is an index representing the degree to which iodine ions exuded from the polarizing plate pass through the optical pressure-sensitive adhesive sheet of the present invention when the optical pressure-sensitive adhesive sheet of the present invention is attached to an iodine-containing polyvinyl alcohol sheet that is a polarizing plate; a smaller value indicates greater suppression of iodine ion pass-through.

[0021] The iodine ion elution amounts I0 and I can be measured, for example, by the ion chromatography method described in the Examples.

[0022] In addition, from the viewpoint of measurement accuracy, the polarizing plate used for measuring the iodine ion elution amounts I0 and I is preferably one in which the iodine ion elution amount I0 is 2.0 ppm or more.

[0023] The weight ratio (I / I0) can be adjusted to a value within a preferred range by, for example, appropriately adjusting the type and content of the unit derived from the nitrogen atom-containing monomer in the acrylic polymer described below.

[0024] 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. In the optical pressure-sensitive adhesive sheet of the present invention, both pressure-sensitive adhesive surfaces may be formed of the same pressure-sensitive adhesive layer, or may be formed of different pressure-sensitive adhesive layers. When formed of different pressure-sensitive adhesive layers, the weight ratio (I / I0) of the entire pressure-sensitive adhesive sheet may be in the above-mentioned range.

[0025] The optical pressure-sensitive adhesive sheet of the present invention may be a "substrate-less pressure-sensitive adhesive sheet" that does not have a substrate (substrate layer), or may be a "substrate-attached pressure-sensitive adhesive sheet" that has a substrate.

[0026] The substrate (substrate layer) is a support that supports the pressure-sensitive adhesive layer, and when the optical pressure-sensitive adhesive sheet of the present invention is attached to an adherend, it is attached to the adherend together with the pressure-sensitive adhesive layer.

[0027] Examples of the substrate include plastic films made from polyester resins (polyethylene terephthalate, etc.), acrylic resins (polymethyl methacrylate, etc.), polycarbonate, triacetyl cellulose, polysulfone, polyarylate, polyimide, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, ethylene-propylene copolymers, cyclic olefin polymers (trade name "Arton" (manufactured by JSR Corporation), trade name "Zeonor" (manufactured by Zeon Corporation), etc.). These plastic materials may be used alone or in combination of two or more. Note that a release liner that is peeled from the adhesive surface during application is not included in the substrate.

[0028] The total light transmittance of the substrate measured in accordance with JIS K7136 is preferably 85% or more, more preferably 88% or more. The haze of the substrate measured in accordance with JIS K7136 is not particularly limited, but is preferably 1.0% or less, more preferably 0.5% or less.

[0029] The thickness of the substrate is not particularly limited, but is preferably 12 to 75 μm, for example. The substrate may be in the form of either a single layer or multiple layers, and the surface may be subjected to a known or commonly used surface treatment, such as a physical treatment such as corona discharge treatment or plasma treatment, or a chemical treatment such as a primer treatment.

[0030] 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 it is applied. Each adhesive surface may be protected by two release liners, or may be protected by a single release liner having release surfaces on both sides in a rolled form (rolled body).

[0031] Examples of the release liner include a substrate having a release-treated layer, a low-adhesion substrate made of a fluoropolymer, a low-adhesion substrate made of a non-polar polymer, etc. The release liner can be formed by a known or conventional method, and the thickness is not particularly limited.

[0032] Examples of the substrate having a release treatment layer include plastic films and papers whose surfaces are treated with a release agent such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide-based release agent.

[0033] Examples of the fluorine-based polymer in the low-adhesion substrate made of the fluorine polymer include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, and chlorofluoroethylene-vinylidene fluoride copolymer.

[0034] Examples of the non-polar polymer include olefin resins (such as polyethylene and polypropylene).

[0035] The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer according to the present invention is not particularly limited as long as the weight ratio (I / I0) is within the preferred range, and examples thereof include acrylic pressure-sensitive adhesive compositions, rubber pressure-sensitive adhesive compositions, vinyl alkyl ether pressure-sensitive adhesive compositions, silicone pressure-sensitive adhesive compositions, polyester pressure-sensitive adhesive compositions, polyamide pressure-sensitive adhesive compositions, urethane pressure-sensitive adhesive compositions, fluorine-based pressure-sensitive adhesive compositions, and epoxy pressure-sensitive adhesive compositions. Among these, acrylic pressure-sensitive adhesive compositions are preferred because they are easy to design pressure-sensitive adhesive compositions with regard to transparency, adhesion, weather resistance, cost, and the like. The pressure-sensitive adhesive compositions may be used alone or in combination of two or more types.

[0036] The acrylic pressure-sensitive adhesive composition contains an acrylic polymer as a base polymer, and the acrylic polymer may be used alone or in combination of two or more kinds.

[0037] The acrylic polymer preferably has a unit derived from a (meth)acrylic acid alkyl ester. Note that "(meth)acrylic" refers to "acrylic" and / or "methacrylic" (either one or both of "acrylic" and "methacrylic"), and the same applies hereinafter. The acrylic polymer may be a random copolymer or a block copolymer.

[0038] The acrylic polymer may contain unpolymerized monomers or oligomers thereof.

[0039] The acrylic polymer according to the present invention preferably contains a unit derived from a nitrogen atom-containing monomer, since it is believed that the nitrogen atom in the structure coordinates with iodine ions and inhibits the permeation of iodine ions. Details of the nitrogen atom-containing monomer will be described later.

[0040] In the pressure-sensitive adhesive layer according to the present invention, it is preferable that the thickness X (μm) of the pressure-sensitive adhesive layer and the content Y (wt %) of units derived from nitrogen atom-containing monomers in the pressure-sensitive adhesive composition (total of the acrylic polymer and additives blended into the acrylic polymer) forming the pressure-sensitive adhesive layer satisfy the following formula (1): 20.0≦(X×Y / 100)≦120.0 (1)

[0041] The above value (X×Y / 100) is an index of the amount of nitrogen atoms present on the path along which iodine ions attempt to permeate the adhesive layer.

[0042] When the value (X×Y / 100) according to the above formula (1) is 20.0 or more and 120.0 or less, the pressure-sensitive adhesive layer is suitable in that it can effectively capture iodine ions and easily suppress permeation while maintaining good transparency.

[0043] The above value (X×Y / 100) is more preferably 22.0 or more, and even more preferably 25.0 or more, since the pressure-sensitive adhesive layer can easily capture iodine ions effectively, and is more preferably 100.0 or less, and even more preferably 80.0 or less, since the pressure-sensitive adhesive layer can easily maintain good transparency.

[0044] The thickness X of the pressure-sensitive adhesive layer is preferably 90 μm or more, more preferably 95 μm or more, and even more preferably 100 μm or more, from the viewpoint of easily suppressing the permeation of iodine ions and moisture while maintaining sufficient adhesive reliability, and is preferably 300 μm or less, more preferably 270 μm or less, and even more preferably 230 μm or less, from the viewpoint of maintaining sufficient transparency.

[0045] The content ratio Y is preferably 20.0% by weight or more, more preferably 23.0% by weight or more, and even more preferably 25.0% by weight or more, from the viewpoint of easily suppressing the permeation of iodine ions, and 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, from the viewpoint of easily suppressing coloration.

[0046] The pressure-sensitive adhesive layer has a moisture permeability of 500 g / (m) at 40°C and 92% RH when the thickness is 100 μm. 2 24 hours or less is preferable.

[0047] The moisture permeability is 500g / (m 2 If the moisture permeability is 24 h or less, the pressure-sensitive adhesive layer can suppress moisture penetration, i.e., penetration into the polarizing plate, and can suppress the release and exudation of iodine ions from the polarizing plate due to the moisture. The moisture permeability can be measured by the method described in the Examples.

[0048] The moisture permeability is 400g / (m 2 24h) or less is more preferable, and even more preferable is 300g / (m 2 The lower limit of the moisture permeability is not particularly limited, but for example, 15 g / (m 2 24h), and 20g / (m 2 24h) or 25g / (m 2 24 hours).

[0049] In the pressure-sensitive adhesive layer, the thickness X (μm) of the pressure-sensitive adhesive layer, the content Y (wt%) of units derived from nitrogen atom-containing monomers in the pressure-sensitive adhesive composition, and the moisture permeability Z (g / (m 2 ·24h)) preferably satisfies the following formula (2): 10.0≦(X×Y / Z)≦120.0 (2)

[0050] The above value (X×Y / Z) is an index of the ease of movement of water and iodine in the adhesive.

[0051] When the value (X×Y / Z) according to the above formula (2) is 10.0 or more and 120.0 or less, the pressure-sensitive adhesive layer is suitable in that it can suppress the penetration of moisture into the polarizing plate and suppress the release of iodine ions from the polarizing plate due to the moisture.

[0052] The above value (X×Y / Z) is more preferably 11.0 or more, and even more preferably 12.0 or more. The upper limit of the above value (X×Y / Z) is more preferably 110.0, and even more preferably 100.0.

[0053] The above value (X×Y / 100), the above moisture permeability, and the above value (X×Y / Z) can be adjusted to values within a preferred range by, for example, appropriately adjusting the type and content of units derived from (meth)acrylic acid alkyl esters, nitrogen atom-containing monomers, hydroxyl group-containing monomers, etc. in the acrylic polymer described below.

[0054] The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer may be, for example, any of an emulsion type, a solvent type (solution type), a type cured by active energy rays (ionizing radiation such as α rays, β rays, γ rays, neutron rays, electron beams, ultraviolet rays, etc.), a hot melt type, etc.

[0055] The acrylic polymer according to the present invention preferably contains a unit derived from a (meth)acrylic acid alkyl ester having a linear or branched alkyl group at the ester terminal. By containing the unit derived from a (meth)acrylic acid alkyl ester, the acrylic polymer can have a group containing an alkyl group in the side chain.

[0056] The alkyl group preferably has 1 to 20 carbon atoms, and specific examples of the (meth)acrylic acid alkyl ester include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, 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-(meth)acrylic acid Examples of suitable acrylates include ethylhexyl, 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, and eicosyl (meth)acrylate.

[0057] Among these, (meth)acrylic acid alkyl esters having an alkyl group (preferably a branched alkyl group) with 8 to 18 carbon atoms are preferred, as they are more likely to inhibit moisture permeation through the pressure-sensitive adhesive layer, and 2-ethylhexyl acrylate and isostearyl acrylate are more preferred.

[0058] The content of the (meth)acrylic acid alkyl ester-derived units in the acrylic polymer is preferably 65.0 wt% or more, more preferably 68.0 wt% or more, and even more preferably 70.0 wt% or more, based on 100 wt% of all monomer-derived units. The upper limit is preferably 80.0 wt%, more preferably 78.0 wt%, and even more preferably 75.0 wt%. When the content of the (meth)acrylic acid alkyl ester-derived units is within the above range, it is easy to achieve a balance between adhesive strength and cohesive strength.

[0059] The content of the units derived from the (meth)acrylic acid alkyl ester having an alkyl group having 8 to 18 carbon atoms is preferably 70.0% by weight or more, more preferably 75.0% by weight or more, and even more preferably 80.0% by weight or more, relative to 100% by weight of the units derived from the (meth)acrylic acid alkyl ester. The upper limit may be, for example, 100% by weight, 98.0% by weight, or 95.0% by weight.

[0060] The (meth)acrylic acid alkyl esters may be used alone or in combination of two or more.

[0061] The acrylic polymer preferably contains a unit derived from another monomer (copolymerizable monomer) having a (meth)acryloyl group or an alkenyl group that can be polymerized with the (meth)acrylic acid alkyl ester. Examples of the copolymerizable monomer include a nitrogen atom-containing monomer and a hydroxyl group-containing monomer.

[0062] Examples of the nitrogen atom-containing monomer include cyclic nitrogen-containing monomers and (meth)acrylamides.

[0063] 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, and isocyanate group-containing monomers.

[0064] Examples of the N-vinyl cyclic amide include N-vinyl cyclic amides represented by the following formula (3): 1 represents a divalent organic group. [ka]

[0065] R in the above formula (1) 1is a divalent organic group, preferably a divalent saturated or unsaturated hydrocarbon group, and more preferably a divalent saturated hydrocarbon group (for example, an alkylene group having 3 to 5 carbon atoms).

[0066] Examples of N-vinyl cyclic amides represented by the above formula (3) include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, and N-vinyl-3,5-morpholinedione.

[0067] Examples of the vinyl monomer having a nitrogen-containing heterocycle include acrylic monomers having a nitrogen-containing heterocycle such as a morpholine ring, a piperidine ring, a pyrrolidine ring, and a piperazine ring.

[0068] Examples of vinyl monomers having a nitrogen-containing heterocycle 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, and (meth)acryloylpiperidine.

[0069] Examples of the (meth)acrylamides include (meth)acrylamide, N-alkyl(meth)acrylamide, N,N-dialkyl(meth)acrylamide, etc. Examples of the N-alkyl(meth)acrylamide include N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, Nn-butyl(meth)acrylamide, N-octyl(meth)acrylamide, etc. Furthermore, the 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)acrylamide 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, and N,N-di(t-butyl)(meth)acrylamide.

[0070] The (meth)acrylamides also include, for example, various N-hydroxyalkyl(meth)acrylamides. Examples of the N-hydroxyalkyl(meth)acrylamides 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, and N-methyl-N-2-hydroxyethyl(meth)acrylamide.

[0071] The (meth)acrylamides also include, for example, various N-alkoxyalkyl(meth)acrylamides, such as N-methoxymethyl(meth)acrylamide and N-butoxymethyl(meth)acrylamide.

[0072] Examples of the amino group-containing monomer include aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, and t-butylaminoethyl (meth)acrylate.

[0073] Examples of the cyano group-containing monomer include acrylonitrile and methacrylonitrile.

[0074] Examples of the imide group-containing monomer include maleimide-based monomers (e.g., N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, etc.), itaconimide-based monomers (e.g., N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-laurylitaconimide, N-cyclohexylitaconimide, etc.), and succinimide-based monomers (e.g., N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, N-(meth)acryloyl-8-oxyoctamethylenesuccinimide, etc.).

[0075] Examples of the isocyanate group-containing monomer include 2-(meth)acryloyloxyethyl isocyanate.

[0076] Of 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.

[0077] The nitrogen atom-containing monomers may be used alone or in combination of two or more.

[0078] The content of the nitrogen atom-containing monomer-derived units in the acrylic polymer is preferably 20.0 wt% or more, more preferably 23.0 wt% or more, and even more preferably 25.0 wt% or more, based on 100 wt% of all monomer-derived units. The upper limit is preferably 40.0 wt%, more preferably 37.0 wt%, and even more preferably 35.0 wt%. When the content of the nitrogen atom-containing monomer-derived units is 20.0 wt% or more, permeation of iodine ions is likely to be suppressed, and when the upper limit is 40.0 wt%, coloration of the pressure-sensitive adhesive layer is likely to be suppressed.

[0079] Examples of the hydroxyl group-containing monomer include hydroxyl group-containing (meth)acrylic acid esters, vinyl alcohol, and allyl alcohol.

[0080] Examples of the hydroxyl group-containing (meth)acrylic acid ester include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, hydroxylauryl (meth)acrylate, and 4-hydroxymethylcyclohexyl (meth)acrylate, and among these, 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are preferred.

[0081] The hydroxyl group-containing monomers may be used alone or in combination of two or more.

[0082] The content of the hydroxyl group-containing monomer-derived units in the acrylic polymer is preferably 0.1 wt% or more, more preferably 0.5 wt% or more, and even more preferably 0.8 wt% or more, based on 100 wt% of all monomer-derived units. The upper limit is preferably 25.0 wt%, more preferably 10.0 wt%, and even more preferably 5.0 wt%. When the content of the hydroxyl group-containing monomer-derived units is 0.1 wt% or more, it becomes easier to adjust the adhesiveness of the pressure-sensitive adhesive composition and the degree of crosslinking by reaction with a crosslinking agent, while when the upper limit is 25.0 wt%, the pressure-sensitive adhesive layer becomes less permeable to moisture.

[0083] In addition to the nitrogen atom-containing monomer and the hydroxyl group-containing monomer, the copolymerizable monomer may include, for example, an alicyclic structure-containing monomer, a carboxy group-containing monomer, an acid anhydride group-containing monomer, a sulfonic acid group- or phosphate group-containing monomer, an epoxy group-containing monomer, an alkoxy group-containing monomer, an alkoxysilyl group-containing monomer, a vinyl ester, a vinyl alkyl ether, an aromatic hydrocarbon group-containing monomer, an olefin, or a diene.

[0084] Examples of the alicyclic monomer 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 (meth)acrylic acid esters having a tricyclic or higher hydrocarbon ring. The cycloalkyl group, the bicyclic hydrocarbon ring, and the tricyclic or higher hydrocarbon ring may have a substituent. Examples of the substituent include halogen atoms (e.g., fluorine atoms, chlorine atoms, bromine atoms, iodine atoms), and linear or branched alkyl groups having 1 to 6 carbon atoms (e.g., methyl groups, ethyl groups, n-propyl groups, isopropyl groups, etc.). The number of the substituents is, for example, 1 to 6. Two or more substituents may be the same or different.

[0085] Examples of the (meth)acrylic acid cycloalkyl ester include cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, cyclooctyl (meth)acrylate, etc. Among these, cyclohexyl acrylate and 3,3,5-trimethylcyclohexyl methacrylate are preferred.

[0086] Examples of the (meth)acrylic acid ester having a bicyclic hydrocarbon ring include bornyl (meth)acrylate and isobornyl (meth)acrylate.

[0087] Examples of the (meth)acrylic acid ester having three or more hydrocarbon rings include dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate.

[0088] The above alicyclic monomers may be used alone or in combination of two or more.

[0089] 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, and even more preferably 3.0% by weight or less, based on 100% by weight of all monomer-derived units. The lower limit may be, for example, 0% by weight.

[0090] 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.

[0091] Examples of the acid anhydride group-containing monomer include maleic anhydride and itaconic anhydride.

[0092] The total content of units derived from carboxyl group-containing monomers and acid anhydride group-containing monomers in the acrylic polymer may be 1% by weight or less, or 0.5% by weight or less, based on 100% by weight of all monomer-derived units, from the viewpoint of preventing metal corrosion. The lower limit is usually 0% by weight, since it is preferable not to use them, at least intentionally.

[0093] Examples of sulfonic acid group or phosphate group-containing monomers include styrenesulfonic acid, allylsulfonic acid, sodium vinylsulfonate, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid, and 2-hydroxyethyl acryloylphosphate.

[0094] Examples of epoxy group-containing monomers include epoxy group-containing acrylates such as glycidyl (meth)acrylate and 2-ethyl glycidyl ether (meth)acrylate, allyl glycidyl ether, and glycidyl ether (meth)acrylate.

[0095] Examples of the alkoxy group-containing monomer include alkoxyalkyl(meth)acrylates, alkoxypolyalkyleneglycol(meth)acrylates, and the like.

[0096] Examples of the alkoxyalkyl (meth)acrylates include 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, propoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, and ethoxypropyl (meth)acrylate.

[0097] Examples of the alkoxypolyalkylene glycol (meth)acrylates include methoxyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate.

[0098] Examples of the alkoxysilyl group-containing monomer include alkoxysilyl group-containing (meth)acrylates and alkoxysilyl group-containing vinyl compounds.

[0099] Examples of the alkoxysilyl group-containing vinyl compound include 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane.

[0100] Examples of the vinyl esters include vinyl acetate and vinyl propionate.

[0101] Examples of the vinyl alkyl ethers include methyl vinyl ether and ethyl vinyl ether.

[0102] Examples of the aromatic hydrocarbon group-containing monomer include aromatic vinyl compounds and (meth)acrylic acid esters having an aromatic hydrocarbon group.

[0103] Examples of the aromatic vinyl compound include styrene, α-methylstyrene, and vinyltoluene.

[0104] Examples of the (meth)acrylic acid ester having an aromatic hydrocarbon group include phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate.

[0105] Examples of the olefins or dienes include ethylene, butadiene, isoprene, and isobutylene.

[0106] In addition to these, the copolymerizable monomers may also 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, and (meth)acrylic acid esters obtained from terpene compound derivative alcohols.

[0107] The copolymerizable monomers may be used alone or in combination of two or more.

[0108] 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, more preferably 5.0% by weight or less, and even more preferably 3.0% by weight or less, based on 100% by weight of all monomer-derived units. The lower limit may be, for example, 0% by weight.

[0109] In addition to the units derived from the monomers constituting the acrylic polymer, the acrylic polymer may contain additives such as polymerization initiators, crosslinking agents, polyfunctional monomers, silane coupling agents, solvents, tackifying resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenols, etc.), antioxidants, fillers, UV absorbers, antioxidants, chain transfer agents, plasticizers, softeners, surfactants, antistatic agents, and rust inhibitors, provided that the effects of the present invention are not impaired. These additives may be used alone or in combination of two or more.

[0110] Examples of the polymerization initiator include a photopolymerization initiator (photoinitiator) and a thermal polymerization initiator. The polymerization initiator may be used alone or in combination of two or more. The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition has sufficient shape stability, and therefore does not necessarily need to contain a polymerization initiator.

[0111] 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, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, and thioxanthone-based photopolymerization initiators.

[0112] Examples of the benzoin ether 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, and anisole methyl ether.

[0113] Examples of the acetophenone-based photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, and 4-(t-butyl)dichloroacetophenone.

[0114] Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one, and the like.

[0115] Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride.

[0116] Examples of the photoactive oxime-based photopolymerization initiator include 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime.

[0117] The benzoin-based photopolymerization initiator includes, for example, benzoin.

[0118] Examples of the benzyl photopolymerization initiator include benzyl.

[0119] Examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexylphenyl ketone.

[0120] Examples of the ketal-based photopolymerization initiator include benzyl dimethyl ketal.

[0121] Examples of the thioxanthone-based photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone.

[0122] When the photopolymerization initiator is used, the amount used is not particularly limited, but is preferably 0.01 to 1.0 part by weight, more preferably 0.04 to 0.5 part by weight, per 100 parts by weight of the acrylic polymer.

[0123] Examples of the thermal polymerization initiator include azo-based polymerization initiators, peroxide-based polymerization initiators (dibenzoyl peroxide, tert-butyl permaleate, etc.), redox-based polymerization initiators, etc. Among these, azo-based polymerization initiators are preferred.

[0124] Examples of the azo-based polymerization initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2-methylpropionate)dimethyl, and 4,4'-azobis-4-cyanovaleric acid.

[0125] When the azo-based 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 0.3 parts by weight, per 100 parts by weight of the acrylic polymer.

[0126] The crosslinking agent can be blended for the purpose of crosslinking within the pressure-sensitive adhesive layer or crosslinking between the pressure-sensitive adhesive layer and its adjacent surface. Specific examples include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, carbodiimide-based crosslinking agents, melamine-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, hydrazine-based crosslinking agents, and amine-based crosslinking agents. These may be used alone or in combination of two or more.

[0127] The isocyanate crosslinking agent is preferably a compound having two or more isocyanate groups in one molecule, and specific examples include aromatic isocyanates (tolylene diisocyanate, xylene diisocyanate, polymethylene polyphenyl diisocyanate, tris(p-isocyanatophenyl)thiophosphate, diphenylmethane diisocyanate, etc.), alicyclic isocyanates (isophorone diisocyanate, etc.), and aliphatic isocyanates (hexamethylene diisocyanate, etc.).

[0128] The epoxy crosslinking agent is preferably a compound having two or more (preferably 3 to 5) epoxy groups in one molecule, and specific examples include N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, and polyglycerol polyglycidyl ether.

[0129] The oxazoline-based crosslinking agent is preferably a compound having one or more oxazoline groups in one molecule.

[0130] Examples of the aziridine crosslinking agent include trimethylolpropane tris[3-(1-aziridinyl)propionate], trimethylolpropane tris[3-(1-(2-methyl)aziridinylpropionate)], and the like.

[0131] The carbodiimide crosslinking agent is preferably a low molecular weight compound or a high molecular weight compound having two or more carbodiimide groups.

[0132] The content of the crosslinking agent is preferably 1.5 parts by weight or less, more preferably 0.001 to 1.5 parts by weight, even more preferably 0.005 to 1.0 part by weight, and particularly preferably 0.010 to 0.5 parts by weight, relative to 100 parts by weight of the acrylic polymer, in order to easily achieve a good balance between adhesive strength and cohesive strength.

[0133] The polyfunctional monomers can be blended in place of or in combination with the crosslinking agents for the purpose of adjusting the cohesive strength, and specific examples thereof 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, dipentaerythritol hexa(meth)acrylate, and the like. (meth)acrylate, ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane 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 be used alone or in combination of two or more.

[0134] The content of the polyfunctional monomer is preferably 1.5 parts by weight or less, more preferably 1.0 part by weight or less, and even more preferably 0.5 parts by weight or less, relative to 100 parts by weight of the acrylic polymer. The lower limit may be 0 part by weight, 0.001 part by weight, 0.005 part by weight, or 0.010 part by weight. When the content of the polyfunctional monomer is within the above range, it is easy to achieve a good balance between adhesive strength and cohesive strength.

[0135] Examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-phenylaminopropyltrimethoxysilane. Among these, γ-glycidoxypropyltrimethoxysilane is preferred. The silane coupling agents may be used alone or in combination of two or more.

[0136] The content of the silane coupling agent in the pressure-sensitive adhesive composition is preferably 0.50 parts by weight or less, more preferably 0.30 parts by weight or less, and even more preferably 0.27 parts by weight or less, relative to 100 parts by weight of the acrylic polymer, from the viewpoint of obtaining reliable adhesion to glass. The lower limit may be 0 part by weight, 0.01 part by weight, or 0.03 part by weight.

[0137] Examples of the solvent include organic solvents such as esters (ethyl acetate, n-butyl acetate, etc.), aromatic hydrocarbons (toluene, benzene, etc.), aliphatic hydrocarbons (n-hexane, n-heptane, etc.), alicyclic hydrocarbons (cyclohexane, methylcyclohexane, etc.), ketones (methyl ethyl ketone, methyl isobutyl ketone, etc.), etc. One or more of the solvents may be used.

[0138] In order to ensure sufficient transparency of the optical adhesive sheet of the present invention, the total content of the above additives is preferably 10.0% by weight or less, more preferably 5.0% by weight or less, even more preferably 3.0% by weight or less, and particularly preferably 1.0% by weight or less.

[0139] The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer according to the present invention can be prepared, for example, by blending additives as necessary with a mixture of monomer components, or a polymer or partial polymer obtained by polymerizing the monomer components by a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a polymerization method using active energy ray irradiation (active energy ray polymerization method), or the like.

[0140] The pressure-sensitive adhesive layer can be 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 it by irradiating it with active energy rays (ionizing radiation such as α rays, β rays, γ rays, neutron rays, electron beams, etc., ultraviolet rays, etc.).

[0141] The application (coating) can be carried out by a known coating method using a coater such as a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater, comma coater, or direct coater.

[0142] The optical adhesive sheet of the present invention can be produced by forming an adhesive layer on a release liner in the case of a substrate-less adhesive sheet, or by forming an adhesive layer directly on the surface of the substrate (direct transfer method) in the case of a substrate-attached adhesive sheet, or by forming an adhesive layer on a release liner and then laminating it to the substrate to form an adhesive layer (transfer method).

[0143] The thickness of the optical pressure-sensitive adhesive sheet of the present invention is not particularly limited, but is preferably 90 μm or more, more preferably 95 μm or more, and even more preferably 100 μm or more. The thickness is preferably 300 μm or less, more preferably 270 μm or less, and even 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.

[0144] The total light transmittance of the optical adhesive sheet of the present invention, measured in accordance with JIS K7136, is not particularly limited, but from the standpoint of appearance characteristics and transparency, it is preferably 85.0% or more, more preferably 90.0% or more, and even more preferably 92.0% or more.

[0145] The haze of the optical pressure-sensitive adhesive sheet of the present invention, measured in accordance with JIS K7136, is preferably 1.0% or less, more preferably 0.5% or less, from the standpoint of appearance characteristics and transparency.

[0146] The optical pressure-sensitive adhesive sheet of the present invention is suitable for use in an image display device, in which an iodine-containing polarizing plate and a photosensor having a silver nanowire layer are bonded together. When bonding the polarizing plate and the photosensor together, the adhesive surface of the pressure-sensitive adhesive layer of the present invention may be attached directly to the polarizing plate and the silver nanowire layer, or may be attached to a resin protective layer that protects the polarizing plate and the silver nanowire layer. Examples of the silver nanowire layer include a layer on which a mesh of silver-containing thin metal wires is printed, and a film (silver nanowire film) formed from silver-containing thin metal wires (nanowires).

[0147] The optical pressure-sensitive adhesive sheet of the present invention may be used for bonding optical components such as 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, anti-reflection films, hard-coated films (films in which a hard coat treatment has been applied to at least one side of a plastic film such as a polyethylene terephthalate film), transparent conductive films, design films, decorative films, surface protection plates, prisms, lenses, color filters, transparent substrates (glass sensors, glass display panels (LCDs, etc.), glass substrates such as glass plates with transparent electrodes), and touch sensors having an ITO (indium tin oxide) layer or a zinc oxide (ZnO) layer.

[0148] As described above, the image display device of the present invention at least comprises a polarizing plate containing iodine, an optical adhesive sheet of the present invention, and an optical sensor having a silver nanowire layer, and preferably comprises the polarizing plate, the optical adhesive sheet of the present invention, and the optical sensor in this order. [Example]

[0149] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0150] <Production Example 1: Preparation of polarizing plate> A laminate consisting of a 9 μm-thick polyvinyl alcohol layer and an amorphous polyethylene terephthalate film substrate was uniaxially stretched by auxiliary in-air stretching at 130° C. to obtain a stretched laminate.

[0151] Next, the stretched laminate was immersed in a dye bath (an aqueous iodine solution containing iodine and potassium iodide in a weight ratio of 1:7 to 100 parts by weight of water) at a liquid temperature of 30°C while adjusting the concentration so that the single transmittance of the final polarizer would be 43.0% or more, thereby obtaining a colored laminate.

[0152] Next, the colored laminate was insolubilized in an insolubilizing bath (a boric acid aqueous solution containing 4 parts by weight of boric acid mixed with 100 parts by weight of water) at a liquid temperature of 65°C, while being uniaxially stretched to a total stretch ratio of 5.94 times, to obtain an optical film laminate having a polarizer (thickness 5 μm) in which iodine adsorbed in the polyvinyl alcohol layer by dyeing was highly oriented in one direction as a polyiodine ion complex.

[0153] A polyvinyl alcohol-based adhesive was applied to the polarizer-side surface of the optical film laminate to a thickness of 1.0 μm, and then an acrylic film (thickness: 20 μm) was laminated as a transparent protective film using a roller. The film was dried at 50°C for 5 minutes, and then the polyethylene terephthalate film substrate was peeled off to obtain a polarizing plate with one side protected.

[0154] A monomer mixture consisting of 99.0 parts by weight of tert-butyl acrylate (BA) and 1.0 part by weight of 4-hydroxybutyl acrylate (4HBA), 0.2 parts by weight of azobisisobutylnitrile, and ethyl acetate was added to a four-neck flask so that the solids content was 20% by weight. The mixture was heated at 60°C under a nitrogen atmosphere for 7 hours to obtain an acrylic polymer with a weight average molecular weight of 1.1 million. To 100 parts by weight of the acrylic polymer solids, 0.8 parts by weight of trimethylolpropane tolylene diisocyanate (trade name "Coronate L" manufactured by Nippon Polyurethane Industry Co., Ltd.) and 0.1 parts by weight of a silane coupling agent (3-glycidoxypropyltrimethoxysilane, trade name "KBM-403" manufactured by Shin-Etsu Chemical Co., Ltd.) were added and mixed uniformly to obtain a pressure-sensitive adhesive composition. The obtained adhesive composition was applied to a polyethylene terephthalate release liner (thickness 38 μm) and dried by heating at normal pressure at 60°C for 1 minute and at 150°C for 1 minute to obtain an adhesive layer (thickness 20 μm).

[0155] The obtained pressure-sensitive adhesive layer (thickness: 20 μm) was transferred to the polarizer side of the above-mentioned polarizing film with one side protected to obtain a polarizing film with a pressure-sensitive adhesive layer (release liner / pressure-sensitive adhesive layer / polarizer / transparent protective film).

[0156] <Production Example 2: Preparation of transparent conductive film> 5 ml of anhydrous ethylene glycol, anhydrous ethylene glycol solution of PtCl2 (1.5 × 10 -40.5 ml of AgNO3 (0.12 mol / L) was added to a reaction vessel equipped with a stirrer and heated at 160°C for 4 minutes to form a solution. Then, 2.5 ml of anhydrous ethylene glycol solution of AgNO3 (0.12 mol / L) and 5 ml of anhydrous ethylene glycol solution of polyvinylpyrrolidone (Mw 55000) (0.36 mol / L) were added dropwise simultaneously over 6 minutes. After the dropwise addition, the reaction was continued at 160°C until AgNO3 was completely reduced, yielding a reaction mixture containing crude silver nanowires. Next, acetone was added to the reaction mixture in a volumetric ratio of 5 times that of the original volume, and the mixture was centrifuged (2000 rpm, 20 minutes) to obtain silver nanowires. The resulting silver nanowires had a minor diameter of 30 nm to 40 nm, a major diameter of 30 nm to 50 nm, and a length of 30 μm to 50 μm.

[0157] 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 liquid.

[0158] In addition, a composition for forming a protective layer was prepared by adding 3.0 parts by weight of dipentaerythritol hexaacrylate (trade name "NK Ester A-DPH", manufactured by Shin-Nakamura Chemical Co., Ltd.) and 0.09 parts by weight of a photopolymerization initiator (trade name "Irgacure 907", manufactured by BASF Japan Ltd.) to 100 parts by weight of a mixed solvent (a 1:1 mixture of isopropyl alcohol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and diacetone alcohol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)).

[0159] A silver nanowire layer was formed by applying a silver nanowire dispersion to a transparent substrate (norbornene-cyclohexane type cyclic olefin film (trade name "ZEONOR" manufactured by Zeon Corporation, in-plane retardation Re: 1.7 nm, thickness direction retardation Rth: 1.8 nm) and drying at 120°C for 2 minutes. Thereafter, a protective layer-forming composition was further applied to the silver nanowire layer side and dried at 120°C for 2 minutes, followed by ultraviolet irradiation (integral illuminance 400 mJ / cm) under an oxygen concentration of 100 ppm. 2The resulting transparent conductive film (transparent substrate / silver nanowire layer / protective layer) had a surface resistance of 50 Ω / □, a total light transmittance of 91.4%, and a haze of 2.0%.

[0160] <Preparation of acrylic adhesive sheet>

[0161] Example 1 A monomer mixture consisting of 36.8 parts by weight of 2-ethylhexyl acrylate (2EHA), 36.8 parts by weight of isostearyl acrylate (ISTA), 0.9 parts by weight of 4-hydroxybutyl acrylate (4HBA), and 25.5 parts by weight of N-vinyl-2-pyrrolidone (NVP) was added to a four-neck flask along with 0.045 parts by weight of 1-hydroxycyclohexylphenyl ketone (trade name "Irgacure 184", manufactured by BASF Japan Ltd.) and 0.045 parts by weight of 2,2-dimethoxy-1,2-diphenyl-1-one (trade name "Irgacure 651", manufactured by BASF Japan Ltd.). The mixture was exposed to ultraviolet light in a nitrogen atmosphere to partially photopolymerize, yielding a partially polymerized product with a polymerization rate of approximately 10%. 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.) and 0.27 parts by weight of a silane coupling agent (3-glycidoxypropyltrimethoxysilane, trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) were added and mixed uniformly to obtain an acrylic pressure-sensitive adhesive composition.

[0162] The acrylic pressure-sensitive adhesive composition was applied to 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. This resulted in a laminate (laminate (I)) having a structure of [release liner / pressure-sensitive adhesive composition layer / release liner]. Next, the laminate (I) was illuminated with a black light (manufactured by Toshiba Corporation) from the top surface (release liner side) of the laminate (I) at an illuminance of 3 mW / cm. 2The adhesive was then irradiated with ultraviolet light for 300 seconds to produce a double-sided PSA sheet (substrate-less PSA sheet) with a structure of [release liner / adhesive layer / release liner] and with both adhesive surfaces protected by release liners. The thickness of the double-sided PSA sheet (excluding the release liner) was 100 μm.

[0163] Example 2 A monomer mixture consisting of 33.8 parts by weight of 2-ethylhexyl acrylate (2EHA), 33.8 parts by weight of isostearyl acrylate (ISTA), 0.8 parts by weight of 4-hydroxybutyl acrylate (4HBA), and 31.6 parts by weight of N-vinyl-2-pyrrolidone (NVP) was added to a four-neck flask along with 0.042 parts by weight of 1-hydroxycyclohexylphenyl ketone (trade name "Irgacure 184", manufactured by BASF Japan Ltd.) and 0.042 parts by weight of 2,2-dimethoxy-1,2-diphenyl-1-one (trade name "Irgacure 651", manufactured by BASF Japan Ltd.). The mixture was exposed to ultraviolet light in a nitrogen atmosphere to partially photopolymerize, yielding a partially polymerized product with a polymerization rate of approximately 10%. To 100 parts by weight of this partial polymer, 0.017 parts by weight of trimethylolpropane triacrylate (trade name "TMP3A", manufactured by Osaka Organic Chemical Industry Co., Ltd.) and 0.25 parts by weight of a silane coupling agent (3-glycidoxypropyltrimethoxysilane, trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) were added and mixed uniformly to obtain an acrylic pressure-sensitive adhesive composition. A pressure-sensitive adhesive sheet (thickness 100 μm excluding the release liner) was produced using the obtained acrylic pressure-sensitive adhesive composition in the same manner as in Example 1.

[0164] Example 3 An adhesive sheet (thickness 100 μm excluding the release liner) was produced in the same manner as in Example 1, except that trimethylolpropane triacrylate (trade name "TMP3A", manufactured by Osaka Organic Chemical Industry Ltd.) was used in an amount of 0.015 parts by weight.

[0165] Example 4 An adhesive sheet (thickness 100 μm excluding the release liner) was produced in the same manner as in Example 3, except that trimethylolpropane triacrylate (TMPTA) (trade name "TMP3A", manufactured by Osaka Organic Chemical Industry Ltd.) was used in an amount of 0.013 parts by weight.

[0166] (Comparative Example 1) A monomer mixture consisting of 40.5 parts by weight of 2-ethylhexyl acrylate (2EHA), 40.5 parts by weight of isostearyl acrylate (ISTA), 1.0 part by weight of 4-hydroxybutyl acrylate (4HBA), and 18.0 parts by weight of N-vinyl-2-pyrrolidone (NVP) was added to a four-neck flask along with 0.050 parts by weight of 1-hydroxycyclohexylphenyl ketone (trade name "Irgacure 184", manufactured by BASF Japan Ltd.) and 0.050 parts by weight of 2,2-dimethoxy-1,2-diphenyl-1-one (trade name "Irgacure 651", manufactured by BASF Japan Ltd.). The mixture was exposed to ultraviolet light in a nitrogen atmosphere to partially photopolymerize, yielding a partially polymerized product with a polymerization rate of approximately 10%. To 100 parts by weight of this partial polymer, 0.150 parts by weight of trimethylolpropane triacrylate (trade name "TMP3A", manufactured by Osaka Organic Chemical Industry Co., Ltd.), 0.30 parts by weight of a silane coupling agent (3-glycidoxypropyltrimethoxysilane, trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.), and 0.15 parts by weight of 1-thioglycerol as a chain transfer agent were added and mixed uniformly to obtain an acrylic pressure-sensitive adhesive composition. A pressure-sensitive adhesive sheet (thickness 100 μm excluding the release liner) was produced using the obtained acrylic pressure-sensitive adhesive composition in the same manner as in Example 1.

[0167] (Comparative Example 2) A monomer mixture consisting 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) was added to a four-neck flask along with 0.048 parts by weight of 1-hydroxycyclohexylphenyl ketone (trade name "Irgacure 184", manufactured by BASF Japan Ltd.) and 0.048 parts by weight of 2,2-dimethoxy-1,2-diphenyl-1-one (trade name "Irgacure 651", manufactured by BASF Japan Ltd.). The mixture was exposed to ultraviolet light in a nitrogen atmosphere to partially photopolymerize, yielding a partially polymerized product with a polymerization rate of approximately 10%. 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.) and 0.34 parts by weight of a silane coupling agent (3-glycidoxypropyltrimethoxysilane, trade name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) were added and mixed uniformly to obtain an acrylic pressure-sensitive adhesive composition. Using the obtained 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.

[0168] (Comparative Example 3) A monomer mixture consisting 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) was added to a four-neck flask along with 0.050 parts by weight of 1-hydroxycyclohexylphenyl ketone (trade name "Irgacure 184", manufactured by BASF Japan Ltd.) and 0.050 parts by weight of 2,2-dimethoxy-1,2-diphenyl-1-one (trade name "Irgacure 651", manufactured by BASF Japan Ltd.). The mixture was exposed to ultraviolet light in a nitrogen atmosphere to partially photopolymerize, yielding a partially polymerized product with a polymerization rate of approximately 10%. To 100 parts by weight of this partial polymer, 0.120 parts by weight of dipentaerythritol hexaacrylate (DPHA) and 0.35 parts by weight of a silane coupling agent (3-glycidoxypropyltrimethoxysilane, product name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.) were added and mixed uniformly to obtain an acrylic pressure-sensitive adhesive composition. A pressure-sensitive adhesive sheet (thickness 100 μm excluding the release liner) was produced using the obtained acrylic pressure-sensitive adhesive composition in the same manner as in Example 1.

[0169] Comparative Example 4 A monomer mixture consisting of 30.0 parts by weight of 2-ethylhexyl acrylate (2EHA), 30.0 parts by weight of isostearyl acrylate (ISTA), 20.0 parts by weight of isobornyl acrylate (IBXA), and 20.0 parts by weight of 4-hydroxybutyl acrylate (4HBA) was mixed with 1-hydroxycyclohexylphenyl ketone (product name "Irgacure 184", manufactured by BASF Japan Ltd.). 0.0500.050 parts by weight of 2,2-dimethoxy-1,2-diphenyl-1-one (trade name "Irgacure 651" manufactured by BASF Japan Ltd.) were placed in a four-neck flask and partially photopolymerized by exposure to ultraviolet light under a nitrogen atmosphere to obtain a partially polymerized product with a polymerization rate of approximately 10%. 100 parts by weight of this partially polymerized product were added with 0.090 parts by weight of 1,6-hexanediol diacrylate (trade name "NK Ester A-HD-N" manufactured by Shin-Nakamura Chemical Co., Ltd.) and 0.30 parts by weight of a silane coupling agent (3-glycidoxypropyltrimethoxysilane, trade name "KBM-403" manufactured by Shin-Etsu Chemical Co., Ltd.) and mixed uniformly to obtain an acrylic pressure-sensitive adhesive composition. A pressure-sensitive adhesive sheet (100 μm thick excluding the release liner) was prepared using the resulting acrylic pressure-sensitive adhesive composition in the same manner as in Example 1.

[0170] <Evaluation> The pressure-sensitive adhesive sheets obtained in the examples and comparative examples were evaluated as follows.

[0171] (1) Amount of iodine ions dissolved

[0172] (Preparation of test specimens) Polarizing plate (9cm) with the release liner removed 2 A polarizing plate (3 cm × 3 cm, square shape) was attached to a glass plate (5 cm × 4.5 cm, thickness 1.2 to 1.5 mm, product name "MICRO SLIDE GLASS S200200", manufactured by Matsunami Glass Industry Co., Ltd.) to prepare a test specimen of "polarizing plate attached to glass plate."

[0173] In addition, the adhesive sheets (16 cm) of the Examples and Comparative Examples were placed so as to completely cover the polarizing plate of the test piece. 2 A polarizing plate (4 cm x 4 cm, square) was attached to one adhesive surface, and then the release liner was peeled off to prepare a test specimen of "a polarizing plate attached to a glass plate and further covered with the above adhesive layer."

[0174] (Iodine ion elution) Next, the test piece of the "polarizing plate attached to a glass plate" and the test piece of the "polarizing plate attached to a glass plate and further covered with the pressure-sensitive adhesive layer" were each immersed in 150 ml of ultrapure water at a temperature of 85°C in a sealed container and heated for 24 hours to elute iodine ions.

[0175] Next, the amount of iodide ions (ppm) in each of the obtained eluates was measured by ion chromatography.

[0176] The weight ratio (I / I) was calculated by dividing the amount of iodine ions (I elution amount I) obtained for the test piece of "polarizing plate attached to glass plate and further covered with the above-mentioned adhesive layer" by the amount of iodine ions (I elution amount I: 2.1 ppm) obtained for the test piece of "polarizing plate attached to glass plate". The results are shown in Table 1.

[0177] The measurement conditions for ion chromatography were as follows.

[0178] (Ion Chromatography Measurement Conditions) 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: 0.25ml / min Sample injection volume: 25 μl

[0179] (2) Corrosion of the silver nanowire layer

[0180] (Preparation of test specimens) A polarizing plate (3 cm × 3 cm, square) from which the release liner had been peeled off was attached to a glass plate (5 cm × 4.5 cm, 1.2 to 1.5 mm thick, product name "MICRO SLIDE GLASS S200200", manufactured by Matsunami Glass Industry Co., Ltd.), and then a pressure-sensitive adhesive sheet (4 cm × 4 cm, square) from each of the Examples and Comparative Examples was attached to one adhesive surface so as to completely cover the polarizing plate. After the release liner had been peeled off, a transparent conductive film (4 cm × 4.5 cm, strip-shaped) was attached to the protective layer side of the adhesive surface to prepare a test specimen.

[0181] (Corrosion evaluation) Next, the test piece was stored in an environment of 65°C and 90% Rh for 100 hours, and then the state thereof was visually observed to evaluate the degree of corrosion of the silver nanowire layer.

[0182] (Corrosion evaluation criteria) 〇 (Good): No corrosion or discoloration △ (slightly poor): No corrosion, but discoloration (yellow) × (bad): Corrosion was present

[0183] (3) Moisture permeability The pressure-sensitive adhesive sheets of the Examples and Comparative Examples were cut into 10 cm diameter circles, and the release liners were peeled off to prepare measurement samples. The moisture permeability of these samples was measured using a water vapor transmission rate measuring device (product name "DELTAPERM", manufactured by Technorox Corporation) under test conditions of 40°C and 90% RH in accordance with the moisture permeability test (cup method) of JIS Z0208.

[0184] (4) Total light transmittance, haze The adhesive sheets of the examples and comparative examples were attached to a glass slide (thickness 0.8 to 1.0 mm, total light transmittance 92%, haze 0.2%, product name "White Polish No. 1", manufactured by Matsunami Glass Industry Co., Ltd.), and the release liner was peeled off to form a measurement sample.The total light transmittance and haze value in the visible light range were measured using a haze meter (product name "HM-150", manufactured by Murakami Color Research Institute Co., Ltd.).

[0185] (5) Transparent stability The adhesive sheets of the Examples and Comparative Examples were attached to a glass slide (thickness 0.8 to 1.0 mm, total light transmittance 92%, haze 0.2%, product name "White Polish No. 1", manufactured by Matsunami Glass Industry Co., Ltd.), and the release liner was peeled off to prepare measurement samples. The stability of the adhesive layer was evaluated by visually observing the condition of the samples after storing them in warm water at 85°C for 24 hours.

[0186] (Evaluation criteria for transparency stability) 〇 (Good): No cloudiness or discoloration × (bad): Cloudy and / or discolored (yellow)

[0187] [Table 1]

[0188] The pressure-sensitive adhesive sheets of Examples 1 to 4 have a weight ratio (I / I0) of 0.015 to 0.018 and a moisture permeability of 171 to 183 g / (m 2 The values (X×Y / 100) and (X×Y / Z) were all within the range of the present invention, with a value of 0 for corrosion of the silver nanowire layer. Furthermore, the pressure-sensitive adhesive sheets of Examples 1 to 4 exhibited excellent optical properties, with a total light transmittance of 92.0%, a haze of 0.2%, and transparency stability of 0.

[0189] On the other hand, the adhesive sheets of Comparative Examples 1 to 4, which were outside the range of the present invention in terms of at least one of the weight ratio (I / I0), moisture permeability, value (X×Y / 100), and value (X×Y / Z), showed poor results of △ or × in terms of corrosion of the silver nanowire layer. [Explanation of symbols]

[0190] 1 Image display device 2a Adhesive layer 2b Adhesive layer 3 Polarizing Plate 4. Silver nanowire layer 5 Base material 6. Light Sensor 7 Image display panel 8 Cover

Claims

1. Below I ０ The weight ratio of I to I ０ ) is 0.05 or less, 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, a thickness X (µm) of the pressure-sensitive adhesive layer and a content Y (wt%) of units derived from nitrogen atom-containing monomers in a pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer satisfy the following formula (1): 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 set to 100 μm; In the pressure-sensitive adhesive layer, the thickness X (μm), the content Y (wt %), and the moisture permeability Z (g / (m 2 ·24 h)) satisfy the following formula (2): I ０ : 9cm attached to a glass plate ２ The amount of iodine ions eluted (ppm) when the polarizing plate was immersed in 150 ml of water at 85°C and stored for 24 hours. I: A 9 cm adhesive sheet attached to a glass plate and covered with the adhesive layer having a thickness of 100 μm. ２ The amount of iodine ions eluted (ppm) when the polarizing plate was immersed in 150 ml of water at 85°C and stored for 24 hours. 20.0≦(X×Y / 100)≦120.0 (1) 10.0≦(X×Y / Z)≦120.0 (2)

2. The optical pressure-sensitive adhesive sheet according to claim 1, wherein the acrylic polymer has a group containing a linear or branched alkyl group having 8 to 18 carbon atoms in a side chain.

3. An image display device comprising a polarizing plate, the optical pressure-sensitive adhesive sheet according to claim 1 or 2, and an optical sensor in this order.

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