Shaped polarizing plate with adhesive layer

Abstract

A shaped polarizing plate with an adhesive layer, which has an adhesive layer on at least one side of a shaped polarizing plate provided with a film on both sides of a polarizing sheet, the shaped polarizing plate being a polarizing plate whose main surface shape is other than a square and a rectangular shape, the adhesive layer satisfying the following requirements (I) or (II): Requirement (I): the 80°C storage modulus (G') of the adhesive layer is 2.0 x 10 4 ~ 1.0 x 10 5 Pa, Requirement (II): the gel fraction of the adhesive layer is 10 to 50 mass%.

Description

TECHNICAL FIELD

[0001] One embodiment of the present application relates to an adhesive layer-attached shaped polarizing plate. BACKGROUND

[0002] Liquid crystal display devices (LCDs) are widely used for televisions, notebook computers, monitors, smartphones, and the like because of their thinness, lightness, and low power consumption. LCDs have a liquid crystal panel component in which polarizing plates are adhered to both sides of a liquid crystal cell with an adhesive, and display is performed by controlling light from a backlight component by the liquid crystal panel component.

[0003] The shape of the main surface of an LCD is generally rectangular, but in recent years, LCDs used for smartphones or car monitors, and the like sometimes adopt a display device having a shape other than a rectangle (shaped), and in this case, an adhesive layer-attached shaped polarizing plate can be used.

[0004] As such an adhesive layer-attached shaped polarizing plate, for example, Patent Literature 1 discloses an adhesive layer-attached polarizing plate characterized in that a non-contact portion not in contact with the adhesive layer is formed at an end portion of the polarizing plate on a surface formed by the adhesive layer of the polarizing plate.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: Japanese Patent Application Laid-Open No. 2017-90896 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] As the above-described polarizing plate, in order to improve its mechanical properties and optical durability, a structure in which a protective film of triacetyl cellulose film or the like is layered on one or both sides of a polarizing film having a polarizing function is generally adopted. In addition, in order to suppress problems such as external light reflection, a structure in which a polarizing film phase difference film is layered is sometimes adopted.

[0010] Each material (each layer) constituting these polarizing plates has different physical and chemical properties, and thus the degree of dimensional change due to shrinkage or swelling caused by the influence of temperature or humidity and stress generated by each material are different, but in the existing polarizing plates whose main surface shape is rectangular or square, problems caused by the dimensional change and stress are not very large.

[0011] However, the above-described conventional adhesive layer-attached polarizing plate cannot sufficiently suppress such light leakage, and there is room for improvement in this regard.

[0012] However, the above-described conventional adhesive layer-attached polarizing plate cannot sufficiently suppress such light leakage, and there is room for improvement in this regard.

[0013] One embodiment of the present invention provides an irregularly shaped polarizing plate with an adhesive layer that can suppress light leakage that is significant when using an irregularly shaped polarizing plate with films on both sides of a polarizer, especially that the light leakage can be suppressed even after a long time at high temperature.

[0014] technical means

[0015] The inventors have conducted in-depth research on methods for solving the above-mentioned technical problems and have found that the above-mentioned technical problems can be solved by the following technical solution, thereby completing the present invention. The technical solution of the present invention is as follows.

[0016] Furthermore, in this specification, the term "polarizing plate" is used to include "polarizing film," and there is no particular distinction between plate, film, sheet, etc.

[0017] [1] A shaped polarizing plate with an adhesive layer, wherein the shaped polarizing plate having films on both sides of the polarizing film has an adhesive layer on at least one side.

[0018] The irregularly shaped polarizing plate is a polarizing plate whose main surface shape is other than square or rectangle.

[0019] The adhesive layer satisfies either (I) or (II) of the following requirements:

[0020] Requirement (I): The storage modulus (G') of the adhesive layer at 80°C is 2.0 × 10⁻⁶. 4 ~1.0×10 5 Pa,

[0021] Requirement (II): The gel fraction of the adhesive layer is 10-50% by mass.

[0022] [2] As described in [1], the irregularly shaped polarizing plate with an adhesive layer, wherein the photoelastic coefficient of the adhesive layer is -400×10⁻⁶. -12 ~400×10 -12 m 2 / N.

[0023] Invention Effects

[0024] According to one embodiment of the present invention, an irregularly shaped polarizing plate with an adhesive layer can be provided that can suppress light leakage that would occur significantly when using an irregularly shaped polarizing plate with films on both sides of a polarizer, especially after a long period of time (e.g., 500 hours) at high temperature (e.g., 80°C).

[0025] In addition, according to one embodiment of the present application, an adhesive-layer-attached shaped polarizing plate that is excellent in long-term reliability (durability) and in which dimensional change or warping due to the polarizing plate is suppressed can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a schematic diagram showing the shape of the main surface of the shaped polarizing plate used in Examples 1 to 3 and Comparative Example 1.

[0027] Figure 2 is a photograph showing the light leakage result in the case of the adhesive-layer-attached shaped polarizing plate obtained in Example 1.

[0028] Figure 3 is a photograph showing the light leakage result in the case of the adhesive-layer-attached shaped polarizing plate obtained in Comparative Example 1.

[0029] Figure 4 is a photograph showing the reference result of light leakage in the case of the adhesive-layer-attached polarizing plate (non-shaped) obtained in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0030] Adhesive-layer-attached shaped polarizing plate

[0031] In the adhesive-layer-attached shaped polarizing plate (hereinafter also referred to as "the present polarizing plate") of one embodiment of the present application, at least one surface of the shaped polarizing plate having a film on both surfaces of a polarizing sheet has an adhesive layer (hereinafter also referred to as "the present adhesive layer") satisfying the following requirements (I) or (II).

[0032] Requirement (I): The 80°C storage modulus (G') of the adhesive layer is 2.0 x 10 4 ~ 1.0 x 10 5 Pa

[0033] Requirement (II): The gel fraction of the adhesive layer is 10 to 50 mass%

[0034] By using the present polarizing plate, light leakage that is likely to occur significantly in the case of using a shaped polarizing plate having a film on both surfaces of a polarizing sheet can be suppressed, and in particular, the light leakage can be suppressed even after a long period (e.g., 500 hours) at a high temperature (e.g., 80°C). The present inventors presume the reason as follows. Note that the following explanation is a presumption and is not any limitation on the present application.

[0035] The irregularly shaped polarizing plate of one embodiment of the present application is a polarizing plate whose main face is shaped other than a square or a rectangle, specifically a polarizing plate whose main face is shaped as a polygon having a vertex with an internal angle of 90° or more (including a concave vertex), a circle, a shape having a curve in part, or a shape having a hole (hollowed out) inside these shapes (including a square or a rectangle).

[0036] The main face of the irregularly shaped polarizing plate refers to one or both of the faces of the polarizing plate having the largest area, and is usually a face perpendicular to the direction of light travel.

[0037] The shape other than a square or a rectangle can be exemplified by a circle (including an ellipse and the like), a triangle, a quadrangle other than a square or a rectangle (for example, a rhombus, a trapezoid), a polygon of five sides or more, a shape having a notch (recess) or a protrusion in at least a part, a shape having a curve, a shape having a hole (hollowed out) inside these shapes (including a square or a rectangle).

[0038] For such an irregularly shaped polarizing plate, the following 1) to 3) can be considered.

[0039] 1) At (i) to (iv) below, the direction of the principal stress generated on the polarizing plate is not perpendicular or parallel to the polarization axis, but is at an angle to the optical axis of the photoelastic birefringence of the polarizing plate (particularly the above-mentioned film) generated by the stress and the polarization axis of the polarizing plate, thereby generating a phase difference from the polarizing plate, resulting in light leakage.

[0040] (i) In the case of a triangle, a quadrangle, and a polygon having a vertex, the vicinity of the vertex

[0041] (ii) In the case of a circle or a shape having a curve in part, the vicinity of a tangent line not perpendicular or parallel to the polarization axis

[0042] (iii) In the case of a shape having a hole (hollowed out) inside, the vicinity of the vertex in the case of a triangle, a quadrangle, and a polygon having a vertex

[0043] (iv) In the case of a shape having a hole (hollowed out) inside, the vicinity of a tangent line not perpendicular or parallel to the polarization axis in the case of a circle or a shape having a curve in part

[0044] 2) The closer the principal stress of the above-mentioned 1) is to the geometric center of the polarizing plate, the greater, and therefore the closer the position of the above-mentioned (i) to (iv) is to the geometric center of the polarizing plate, the more the amount of light leakage.

[0045] 3) The photoelastic birefringence of the above-mentioned 1) is determined by the magnitude of the stress generated by the polarizing plate.

[0046] As described above, the shape of the main surface of the shaped polarizing plate is more likely to cause light leakage than the square or rectangular polarizing plate. In addition, according to the above 2), the effect of the present application is particularly likely to be exerted for the shape having a hole (hollow) in the inside such as (iii) and (iv) of the above 1). In contrast, the effect of the present application is not likely to be exerted for the case where the shape of the main surface is a perfect circle.

[0047] As described above, in order to suppress the light leakage caused when the shaped polarizing plate is used, it is considered that (A) reducing the photoelastic coefficient of the polarizing plate and (B) reducing the stress of the polarizing plate at the portion described in 1) of the above are effective, and (B) is particularly important for the shaped polarizing plate.

[0048] Therefore, by using the present polarizing plate, since the present adhesive layer is provided on at least one surface of the shaped polarizing plate, it is considered that the stress of the polarizing plate at the portion described in 1) of the above (B) can be reduced by relaxing the stress generated on the shaped polarizing plate (particularly, the film), and the light leakage caused when the shaped polarizing plate is used can be suppressed.

[0049] [Adhesive layer]

[0050] The present polarizing plate can have the present adhesive layer on at least one surface of the shaped polarizing plate, or can have the present adhesive layer on both surfaces of the shaped polarizing plate.

[0051] The present adhesive layer is not particularly limited as long as the following requirements (I) or (II) are satisfied, but it is preferable to satisfy the following requirements (I) and (II) from the viewpoint of more exerting the above effects and the like.

[0052] By using the adhesive layer satisfying the following requirements (I) or (II), it is considered that the dimensional change and the stress generated on the polarizing plate can be relaxed, and thus the above effects are exerted.

[0053] Requirement (I): The storage modulus (G') of the present adhesive layer at 80°C is 2.0 x 10 4 Pa to 1.0 x 10 5 Pa

[0054] The storage modulus (G') is preferably 2.5 x 10 4 Pa or more, and 1.0 x 10 4 Pa or less, and more preferably 5.0 x 10 5 Pa or less. 4 Pa or less. 4 Pa or less.

[0055] The storage modulus of the present adhesive layer within the above range can easily suppress light leakage, particularly after a long period of time (e.g., 500 hours) at high temperature (e.g., 80°C), and further can not easily cause warpage or peeling at the interface with the polarizing plate, and thus the present polarizing plate having high reliability can be easily obtained.

[0056] The storage modulus (G') described above can be measured by the method described in the following examples.

[0057] Requirement (II): The gel fraction of the present adhesive layer is 10 to 50 mass%

[0058] The gel fraction described above is 10 mass% or more, preferably 15 mass% or more, and 50 mass% or less, preferably 48 mass% or less, more preferably 45 mass% or less.

[0059] The gel fraction of the present adhesive layer within the above range can easily suppress light leakage, particularly after a long period of time (e.g., 500 hours) at high temperature (e.g., 80°C), and further can not easily cause warpage or peeling at the interface with the polarizing plate, and thus the present polarizing plate having high reliability can be easily obtained.

[0060] The gel fraction described above can be measured by the method described in the following examples.

[0061] The photoelastic coefficient of the present adhesive layer is preferably -400 x 10 -12 m 2 / N or more, more preferably -300 x 10 -12 m 2 / N or more, preferably 400 x 10 -12 m 2 / N or less, more preferably 300 x 10 -12 m 2 / N or less.

[0062] The photoelastic coefficient of the present adhesive layer within the above range can reduce the phase difference from the adhesive layer, and thus can more highly suppress light leakage.

[0063] The photoelastic coefficient described above can be measured by the method described in the following examples.

[0064] The thickness of the present adhesive layer is not particularly limited, but from the viewpoint of being able to easily obtain an adhesive layer having sufficient adhesiveness and the like, it is usually 5 μm or more, preferably 10 μm or more, and usually 75 μm or less, preferably 50 μm or less.

[0065] <Adhesive Composition>

[0066] The adhesive layer is not particularly limited as long as it satisfies the above-mentioned requirements (I) or (II), but from the viewpoint of being able to easily obtain an adhesive layer or the like that exhibits the above-mentioned effects, a (meth)acrylic adhesive layer is preferred.

[0067] The above-mentioned (meth)acrylic adhesive layer can be formed using, for example, an adhesive composition containing a (meth)acrylic polymer. The adhesive composition can contain a crosslinking agent, a silane coupling agent, and other components.

[0068] Furthermore, (meth)acrylic acid in the present application means acrylic acid and / or methacrylic acid. The same applies to the same expression.

[0069] • (Meth)acrylic polymer

[0070] The (meth)acrylic polymer can preferably be synthesized by copolymerizing monomer components containing an alkyl (meth)acrylate (a-1) and / or an alkoxy group-containing (meth)acrylate (a-2), a monomer (b) having a crosslinkable functional group, and, as necessary, an aromatic ring-containing monomer (c) and other monomers (d) other than these monomers.

[0071] As the above-mentioned alkyl (meth)acrylate (a-1), the following can be exemplified: methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, isododecyl (meth)acrylate.

[0072] As the above-mentioned alkyl (meth)acrylate (a-1), from the viewpoint of being able to easily form an adhesive layer or the like having a storage modulus (G') within the above-mentioned range, n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are preferred.

[0073] As the above-mentioned alkoxy group-containing (meth)acrylate (a-2), the following alkoxy group-containing (meth)acrylates can be exemplified: methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, and the like.

[0074] As the above-mentioned alkoxy group-containing (meth)acrylate (a-2), from the viewpoint of being able to easily form an adhesive layer or the like having a storage modulus (G') within the above-mentioned range, methoxyethyl (meth)acrylate is preferred.

[0075] The above (meth) acrylic acid alkyl ester (a-1) and / or the alkoxyl group-containing (meth) acrylic acid ester (a-2) can be used singly or two or more kinds can be used.

[0076] The amount of the above (meth) acrylic acid alkyl ester (a-1) and alkoxyl group-containing (meth) acrylic acid ester (a-2) is preferably 55% by mass or more, more preferably 60% by mass or more, and is preferably 98% by mass or less, more preferably 95% by mass or less, relative to 100% by mass of the total of the monomers at the time of synthesizing the (meth) acrylic acid polymer.

[0077] As the above monomer (b) having a crosslinkable functional group, a hydroxyl group-containing monomer such as 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 1,4-cyclohexane dimethanol mono(meth) acrylate, (meth) acrylate-chloro-2-hydroxypropyl ester, allyl alcohol, and the like can be exemplified.

[0078] A carboxyl group-containing monomer such as acrylic acid, methacrylic acid, β-carboxyethyl (meth) acrylate, 5-carboxypentyl (meth) acrylate, succinic acid mono(meth) acryloyloxyethyl ester, ω-carboxypolycaprolactone mono(meth) acrylate, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, and the like can be exemplified.

[0079] The above monomer (b) having a crosslinkable functional group can be used singly or two or more kinds can be used.

[0080] The amount of the above monomer (b) having a crosslinkable functional group is preferably 0.5% by mass or more, more preferably 1% by mass or more, and is preferably 10% by mass or less, more preferably 8% by mass or less, relative to 100% by mass of the total of the monomers at the time of synthesizing the (meth) acrylic acid polymer.

[0081] As the above aromatic ring-containing monomer (c), benzyl (meth) acrylate, phenyl (meth) acrylate, phenoxyethyl (meth) acrylate can be exemplified.

[0082] By using the above aromatic ring-containing monomer (c), light leakage can be more highly suppressed. In addition, by using the aromatic ring-containing monomer (c), an adhesive layer having a photoelastic coefficient within the above range can be easily obtained.

[0083] The above aromatic ring-containing monomer (c) can be used singly or two or more kinds can be used.

[0084] The above-mentioned aromatic ring-containing monomer (c) is an arbitrary component, but in the case where the aromatic ring-containing monomer (c) is used, the amount thereof is preferably 0.5% by mass or more, more preferably 1% by mass or more, and preferably 30% by mass or less, more preferably 25% by mass or less, with respect to 100% by mass of the total amount of monomers at the time of synthesis of the (meth)acrylic polymer.

[0085] As the above-mentioned other monomer (d), the following can be exemplified:

[0086] (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, (meth)acryloyl morpholine, N-vinylacetamide, diacetone (meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, N,N-diethylaminoethyl(meth)acrylamide, vinylpyrrolidone, hydroxymethyl(meth)acrylamide, methoxyethyl(meth)acrylamide, and the like;

[0087] N,N-dimethylaminoethyl(meth)acrylate, morpholinoethyl(meth)acrylate, and the like;

[0088] cyclohexyl(meth)acrylate, isobornyl(meth)acrylate, adamantyl(meth)acrylate, and the like;

[0089] glycidyl(meth)acrylate, and the like;

[0090] acetoxyethyl(meth)acrylate, and the like;

[0091] vinyl acetate; vinyl chloride; acrylonitrile; methacrylonitrile.

[0092] The above-mentioned other monomer (d) can be used singly or two or more kinds thereof can be used in combination.

[0093] The above-mentioned other monomer (d) is an arbitrary component, but in the case where the other monomer (d) is used, the amount thereof is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and preferably 15% by mass or less, more preferably 10% by mass or less, with respect to 100% by mass of the total amount of monomers at the time of synthesis of the (meth)acrylic polymer.

[0094] The (meth)acrylic polymer preferably has a weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) in terms of a polystyrene equivalent value of 500,000 or more, more preferably 600,000 or more, and preferably 2,000,000 or less, more preferably 1,800,000 or less, from the viewpoint of being able to easily obtain an adhesive layer or the like which is excellent in adhesion and durability and which is excellent in followability to dimensional changes and stress of a polarizing plate.

[0095] From the viewpoint of being able to easily obtain an adhesive layer or the like that is excellent in balance of properties as an adhesive, particularly excellent in adhesive properties, the content of the above (meth)acrylic polymer is preferably 60 to 99.9% by mass, more preferably 65 to 99.9% by mass, relative to 100% by mass of the solid content of the above adhesive composition.

[0096] The above (meth)acrylic polymer can be synthesized by copolymerization of the above monomer components.

[0097] As a method of copolymerization, for example, a conventionally known polymerization method such as solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, etc. can be used, of which solution polymerization is preferred.

[0098] Specifically, for example, a polymerization solvent and monomer components are added to a reaction vessel, a polymerization initiator is added under an atmosphere of an inert gas such as nitrogen, the reaction start temperature is set to usually 40°C or higher, preferably 50°C or higher, and usually 100°C or lower, preferably 90°C or lower, the reaction system is maintained at a temperature of usually 50 to 90°C, preferably 60 to 90°C, and, for example, the reaction is carried out for 3 to 20 hours, whereby a (meth)acrylic polymer can be synthesized.

[0099] In addition, in the above polymerization reaction, a polymerization initiator, a chain transfer agent, a polymerizable monomer, a polymerization solvent can also be added as appropriate.

[0100] As the above polymerization initiator, a peroxide-based polymerization initiator, an azo-based initiator can be exemplified.

[0101] The above polymerization initiator can be used singly or two or more kinds can be used. Furthermore, the polymerization initiator can be added several times in the polymerization.

[0102] As the above peroxide-based polymerization initiator, the following can be exemplified: t-butyl hydroperoxide, cumene hydroperoxide, dicumene hydroperoxide, benzoyl peroxide, lauroyl peroxide, hexanoyl peroxide, diisopropyl peroxide dicarbonate, di-2-ethylhexyl peroxide dicarbonate, t-butyl peroxypivalate, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane, 2,2-bis(4,4-di-t-amylperoxycyclohexyl)propane, 2,2-bis(4,4-di-t-octylperoxycyclohexyl)propane, 2,2-bis(4,4-di-α-cumylperoxycyclohexyl)propane, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)butane, 2,2-bis(4,4-di-t-octylperoxycyclohexyl)butane, di-t-butyl peroxide terephthalate.

[0103] As the above-mentioned azo-based initiator, for example, azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2-(carbamoylazo)isobutyronitrile, 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 2,2'-azobis(2-amino-dipropylpropane) dihydrochloride, 2,2'-azobis(N,N'-dimethylisobutyramidine), 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide], 2,2'-azobis(isobutylamide) diacetate, 4,4'-azobis(4-cyanopentanoic acid), 2,2'-azobis(2-cyanopropanol), dimethyl-2,2'-azobis(2-methylpropionate), and 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide) can be mentioned.

[0104] The above-mentioned polymerization initiator is generally used in an amount of 0.001 parts by mass or more, preferably 0.005 parts by mass or more, and usually 5 parts by mass or less, preferably 3 parts by mass or less, relative to 100 parts by mass of the monomer component for forming the (meth)acrylic polymer.

[0105] As the above-mentioned polymerization solvent, aromatic hydrocarbons such as benzene, toluene, xylene, and the like; aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, n-octane, and the like; alicyclic hydrocarbons such as cyclopentane, cyclohexane, cycloheptane, cyclooctane, and the like; ethers such as diethyl ether, diisopropyl ether, 1,2-dimethoxyethane, dibutyl ether, tetrahydrofuran, dioxane, anisole, phenetol, diphenyl ether, and the like; halogenated hydrocarbons such as chloroform, carbon tetrachloride, 1,2-dichloroethane, chlorobenzene, and the like; esters such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, and the like; ketones such as acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, cyclohexanone, and the like; amides such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and the like; nitriles such as acetonitrile, benzonitrile, and the like; and sulfoxides such as dimethyl sulfoxide, sulfolane, and the like can be mentioned.

[0106] One kind of polymerization solvent can be used, or two or more kinds of polymerization solvents can be used.

[0107] • Crosslinking agent

[0108] The adhesive composition can optionally contain a crosslinking agent.

[0109] Such a crosslinking agent is not particularly limited as long as it is a crosslinking agent that can react with the (meth)acrylic polymer at ordinary temperature or under heating to form a crosslinked structure, and azo-based crosslinking agents, isocyanate-based crosslinking agents, epoxy-based crosslinking agents, metal chelate-based crosslinking agents, and aziridine-based crosslinking agents can be mentioned. Among these, isocyanate-based crosslinking agents are particularly preferred.

[0110] When the above crosslinking agent is used, the crosslinking agent used can be one or two or more.

[0111] As the above isocyanate-based crosslinking agent, there can be mentioned isocyanate compounds such as m-xylylene diisocyanate, toluene diisocyanate, chlorophenyl diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, o-xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and reaction products containing isocyanate groups obtained by reacting these isocyanate compounds with dihydric or higher alcohols such as trimethylolpropane, and derivatives of these isocyanates such as isocyanurates.

[0112] As the above epoxy-based crosslinking agent, there can be mentioned ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, N,N,N',N'-tetraglycidylaminophenylmethane, isocyanuric acid triglycidyl ester, m-N,N-diglycidylaminophenyl glycidyl ether, N,N-diglycidyltoluidine, N,N-diglycidylaniline.

[0113] As the above metal chelate-based crosslinking agent, there can be mentioned compounds in which an alkoxide, acetylacetone, ethyl acetoacetate or the like is coordinated to a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, zirconium or the like.

[0114] When the above crosslinking agent is used, the content of the crosslinking agent relative to 100 parts by mass of the (meth)acrylic polymer in the adhesive composition is preferably 0.02 parts by mass or more, more preferably 0.03 parts by mass or more, and further preferably 0.04 parts by mass or more, and is preferably 2 parts by mass or less, more preferably 1 part by mass or less, and further preferably 0.5 parts by mass or less, from the viewpoint of the balance of properties as an adhesive and the like.

[0115] The use of a crosslinking agent within the above range makes it possible to easily form an adhesive layer having a storage modulus or a gel fraction within the above range.

[0116] • Silane coupling agent

[0117] The above adhesive composition can optionally contain a silane coupling agent.

[0118] Such silane coupling agents can be exemplified by: vinyltrimethoxysilane, vinyltriethoxysilane, methacryloyloxypropyltrimethoxysilane, and the like silane compounds containing a polymerizable unsaturated group; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and the like silane compounds containing an epoxy group; 3- aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2- aminoethyl)-3-aminopropylmethyldimethoxysilane, and the like silane compounds containing an amino group; 3-chloropropyltrimethoxysilane; 3-(trimethoxysilyl)propyl 3-oxobutanoate; and oligomer-type silane coupling agents.

[0119] In the case of using the above-described silane coupling agent, the silane coupling agent used can be one or two or more.

[0120] In the case of using the above-described silane coupling agent, the content of the silane coupling agent is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, with respect to 100 parts by mass of the (meth)acrylic polymer in the adhesive composition, from the viewpoint of being able to easily obtain an adhesive layer or the like having excellent adhesion.

[0121] • Other components

[0122] The above-described adhesive composition can optionally further contain other components, within a range not impairing the effects of the present application. As such other components, specifically mentionable are antistatic agents, organic solvents, tackifying resins, adhesion-reducing agents, antioxidants, ultraviolet absorbers, metal corrosion preventives, crosslinking accelerators, plasticizers, organic particles, inorganic particles, and the like.

[0123] The above-described other components can each be used singly or two or more.

[0124] <Method for forming adhesive layer>

[0125] The method for forming the adhesive layer of the present application is not particularly limited, and the following methods can be exemplified.

[0126] The above-mentioned adhesive composition is applied to a substrate subjected to release treatment. In the case where the above-mentioned adhesive composition contains a solvent, the coating film is formed by drying at usually 50°C or higher, preferably 60°C or higher, and usually 150°C or lower, preferably 100°C or lower, for usually 1 minute or more, preferably 2 minutes or more, and usually 10 minutes or less, preferably 7 minutes or less, to remove the solvent. Subsequently, another substrate subjected to release treatment or a polarizing plate is attached to the surface of the coating film (adhesive layer) on the side of the substrate not subjected to release treatment. Then, the adhesive layer is formed by curing for usually 1 day or more, preferably 3 to 10 days, in an environment of usually 5°C or higher, preferably 15°C or higher, and usually 60°C or lower, preferably 40°C or lower, and usually 30 to 70% RH, preferably 40 to 70% RH. The above-mentioned curing is also referred to as aging. Aging is performed under the above-mentioned conditions using an adhesive composition containing a crosslinking agent, whereby crosslinking is performed during aging and a crosslinked body is efficiently formed.

[0127] The above-mentioned substrate is not particularly limited, and examples thereof include substrates made of plastic, paper, metal, glass, and ceramic. The thickness of the substrate is also not particularly limited, but is usually 10 to 500 μm.

[0128] The above-mentioned plastic includes, for example, polyethylene terephthalate (PET), polyvinyl chloride, polyolefin (polypropylene, polyethylene, TPO (olefin-based thermoplastic elastomer)), polymethyl methacrylate, polycarbonate, polyimide, and ABS.

[0129] The above-mentioned method of applying the adhesive composition includes publicly known methods such as spin coating, knife coating, roll coating, bar coating, blade coating, die coating, gravure coating, and doctor blade method.

[0130] <Shaped Polarizing Plate>

[0131] The above-mentioned shaped polarizing plate can be a polarizing plate in which a film is provided on both sides of a polarizing sheet, and the shape of the main surface thereof is shaped.

[0132] The above-mentioned shaped polarizing plate can further include other layers such as an antiglare layer, a phase difference layer, and a viewing angle enhancement layer.

[0133] The thickness of the above-mentioned shaped polarizing plate is not particularly limited, but is usually 10 μm or more, preferably 15 μm or more, and is usually 500 μm or less, preferably 300 μm or less.

[0134] [Polarizing Sheet]

[0135] As the polarizing plate, a stretched film obtained by containing a polarizing component in a film composed of a polyvinyl alcohol-based resin and stretching it can be exemplified. As the polyvinyl alcohol-based resin, for example, polyvinyl alcohol, polyvinyl formal, polyvinyl acetal, saponified product of ethylene-vinyl acetate copolymer can be exemplified. As the polarizing component, iodine and / or dichroic dye can be exemplified.

[0136] The thickness of the polarizing plate is not particularly limited, and is usually 0.1 μm or more, preferably 1 μm or more, and is usually 100 μm or less, preferably 50 μm or less.

[0137] [Membrane]

[0138] As the membrane, there is no particular limitation, and a film used for a polarizing plate in the past can be exemplified, and as a preferable example, a protective film (polarizing plate protective film), a phase difference film can be exemplified.

[0139] The anisotropic polarizing plate is not particularly limited as long as the above-mentioned membrane is present on both sides of the polarizing plate, and for example, 2 or more layers of protective film can be present, 2 or more layers of phase difference film can be present, and 1 or more layers of protective film and 1 or more layers of phase difference film can be present.

[0140] • Protective film

[0141] As the protective film, a film composed of a thermoplastic resin can be exemplified.

[0142] As the thermoplastic resin, cellulose resin such as triacetyl cellulose, polyester resin, polyether sulfone resin, polysulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, (meth)acrylic resin, cyclic polyolefin resin (norbornene-based resin), polyarylate resin, polystyrene resin, polyvinyl alcohol resin, and a mixture of two or more selected from these resins can be exemplified.

[0143] The thickness of the protective film is not particularly limited, but is usually 10 μm or more, preferably 20 μm or more, and is usually 150 μm or less, preferably 130 μm or less.

[0144] • Phase difference film

[0145] As the phase difference film, there is no particular limitation, and a film made of a resin can be exemplified. As the resin, polyester resin, polyether sulfone resin, polysulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, (meth)acrylic resin, cyclic polyolefin resin (norbornene-based resin), polyarylate resin, polystyrene resin, polyvinyl alcohol resin, and a mixture of two or more selected from these resins can be exemplified.

[0146] The thickness of the above-mentioned phase difference film is not particularly limited, but is usually 10 μm or more, preferably 20 μm or more, and is usually 150 μm or less, preferably 130 μm or less.

[0147] <Method for manufacturing the present polarizing plate>

[0148] The method for manufacturing the present polarizing plate is not particularly limited, but the following methods can be exemplified.

[0149] The method for manufacturing the laminate [substrate subjected to peeling treatment / adhesive layer / polarizing plate] using the same method as described in the above-mentioned method for forming the adhesive layer, or the method for forming the laminate [substrate subjected to peeling treatment / adhesive layer / substrate subjected to peeling treatment], peeling off one of the substrates subjected to peeling treatment from the laminate, and attaching the polarizing plate to the exposed adhesive layer.

[0150] The present polarizing plate thus obtained can be processed into a desired shape as needed.

[0151] Examples

[0152] One embodiment of the present application will be specifically described below based on examples, but the present application is not limited to these examples.

[0153] [Example 1]

[0154] In a reaction apparatus equipped with a stirrer, a reflux cooler, a thermometer, and a nitrogen introduction tube, 76.5 parts by mass of n-butyl acrylate (BA), 3 parts by mass of 2-hydroxyethyl acrylate (2HEA), 0.5 parts by mass of acrylic acid (AA), 20 parts by mass of benzyl acrylate (BzA), and 100 parts by mass of ethyl acetate solvent were charged, and warmed to 70°C while introducing nitrogen. Next, 0.1 parts by mass of 2,2'-azobisisobutyronitrile was added, and a polymerization reaction was performed at 70°C for 6 hours under a nitrogen atmosphere. After the completion of the reaction, the reaction solution was diluted with ethyl acetate to prepare a polymer solution 1 containing an acrylic polymer having a solid content concentration of 30% by mass. The weight average molecular weight (Mw) of the obtained acrylic polymer was 1.4 million.

[0155] In addition, the Mw of the acrylic polymer was calculated from a standard polystyrene under the following conditions by a gel permeation chromatography (GPC) method.

[0156] • Measurement device: HLC-8120 GPC (manufactured by Tosoh Corporation)

[0157] • GPC column configuration: 5 connected columns (all manufactured by Tosoh Corporation)

[0158] (1) TSK-GEL HXL-H (guard column)

[0159] (2) TSK-GEL G7000HXL

[0160] (3) TSK-GEL GMHXL

[0161] (4) TSK-GEL GMHXL

[0162] (5) TSK-GEL G2500HXL

[0163] • Sample concentration: diluted to 1.0 mg / cm with tetrahydrofuran 3

[0164] • Mobile phase solvent: tetrahydrofuran

[0165] • Flow rate: 1.0 cm 3 / min

[0166] • Column temperature: 40°C

[0167] The obtained polymer solution 1 (solid content concentration 30 mass%) and 0.045 parts by mass of an isocyanate-based crosslinking agent ("TD-75" manufactured by Sanko Chemical Industry Co., Ltd.) relative to 100 parts by mass (solid content amount) of the acrylic polymer contained in the polymer solution 1 and 0.5 parts by mass of a silane coupling agent ("KBM-403" manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed to obtain an adhesive composition.

[0168] On a polyethylene terephthalate film (PET film) subjected to a release treatment, the obtained adhesive composition (composition after defoaming) was applied using a doctor blade, and a coating film having a dry film thickness of 20 μm was formed by drying at 90°C for 3 minutes. On the surface of the formed coating film opposite to the adhering surface of the above PET film, a PET film subjected to a release treatment was further adhered, and it was allowed to stand in an environment of 23°C / 50% RH for 7 days to allow it to age, and the coating film was peeled from the two PET films, whereby an evaluation adhesive layer having a thickness of 20 μm was obtained.

[0169] <Storage modulus>

[0170] A test piece for storage modulus measurement having a thickness of 1 mm was prepared by laminating 50 pieces of the obtained evaluation adhesive layer. Using this test piece, a storage modulus (G') at 80°C was measured using a modular compact rheometer MCR300 manufactured by Anton Paar. In addition, the measurement frequency was 1 Hz.

[0171] The storage modulus (G') of the evaluation adhesive layer obtained in Example 1 was 3.0 x 10 4 Pa.

[0172] <Gel fraction>

[0173] Approximately 0.1 g of the obtained evaluation adhesive layer (adhesive layer sampling mass) was collected into a sampling bottle. 30 mL of ethyl acetate was added, and the mixture was shaken for 4 hours. The contents of the sample bottle were then filtered through a 200-mesh stainless steel mesh. The residue on the mesh was dried at 100°C for 2 hours, and the dried mass was measured. The gel fraction of the evaluation adhesive layer was calculated using the following formula.

[0174] The gel fraction of the adhesive layer used for evaluation obtained in Example 1 was 40% by mass.

[0175] Gel fraction (mass %) = (dry mass / adhesive layer sample mass) × 100 (%)

[0176] <Photoelastic coefficient>

[0177] Fifty evaluation adhesive layers were laminated at 23°C / 50% RH and treated in an autoclave at 50°C / 5 atm for 20 minutes to prepare 1.0 mm thick test pieces for photoelasticity coefficient determination. The test pieces were cut to 15 mm × 50 mm and mounted on an automatic wavelength scanning ellipsometer (model "M-220", manufactured by Nippon Spectrophotometer Co., Ltd.). The retardation was measured while stress was applied (measurement wavelength: 633 nm). The slope of the straight line with stress as the horizontal axis and retardation as the vertical axis represents the photoelasticity coefficient of the evaluation adhesive layer.

[0178] The photoelasticity of the evaluation adhesive layer obtained in Example 1 was -50 × 10⁻⁶. -12 m 2 / N.

[0179] <Light Leakage Test>

[0180] An adhesive composition (de-bubbled composition) is applied to a peeled polyethylene terephthalate (PET) film using a doctor blade and dried at 90°C for 3 minutes to obtain a sheet with a coated film thickness of 20 μm. The polyvinyl alcohol film used as the offset sheet has triacetyl cellulose films (protective films) on both sides, and the main surface is circular in shape. Figure 1 On one side of a polarizing plate (60 μm thick) of shape A, the resulting sheet is bonded together with the coated side of the sheet in contact with the protective film side. The sheet is then left to stand for 7 days at 23°C / 50%RH to mature, resulting in a polarizing plate with an adhesive layer and a polarizing plate having an adhesive layer of 20 μm thickness.

[0181] Two pieces of the polarizing plate with the adhesive layer were prepared, and after peeling the PET films from the resulting two pieces of the polarizing plate with the adhesive, the polarizing plates were attached to both sides of an alkali glass plate having a thickness of 0.5 mm with the polarization axes of the polarizing plates orthogonal to each other and the adhesive layers in contact with the alkali glass plate using a laminating roll, and the laminate for light leakage test was obtained by keeping in an autoclave adjusted to 50°C / 5 atm for 20 minutes.

[0182] The resulting laminate for light leakage test was irradiated with light from a backlight of a liquid crystal monitor, and the light leakage at this time was photographed using a luminance meter, and the light leakage was observed (initial light leakage). The results of the initial light leakage are shown in A-1 of Table 1. Figure 2

[0183] Further, the light leakage after 80°C x 500 hours was confirmed in the same manner except that the laminate for light leakage test obtained after keeping at a temperature of 80°C / dry for 500 hours was used. The results of the light leakage after 80°C x 500 hours are shown in A-2 of Table 1. Figure 2

[0184] The initial and light leakages after 80°C x 500 hours were observed in the same manner as described above except that a polarizing plate in which the shape of the main surface was a shape having a hole (hollowed out) (the shape shown in B of Table 1) was used instead of the polarizing plate in which the shape of the main surface was a circular shape (the shape shown in A of Table 1). The results are shown in B-1 and B-2 of Table 1, respectively. Figure 1 Figure 1 Figure 2

[0185] Further, the initial and light leakages after 80°C x 500 hours were observed in the same manner as described above except that a polarizing plate in which the shape of the main surface was a shape having a notch (recess) (the shape shown in C of Table 1) was used instead of the polarizing plate in which the shape of the main surface was a circular shape (the shape shown in A of Table 1). The results are shown in C-1 and C-2 of Table 1, respectively. Figure 1 Figure 1 Figure 2

[0186] Further, the results of the light leakage test were also judged visually according to the following criteria.

[0187] Good: No light leakage was confirmed after 80°C x 500 hours, or although a little light leakage was confirmed, there was no problem in practical use.

[0188] Possible: Light leakage was confirmed after 80°C x 500 hours, but there was no problem in practical use.

[0189] Not possible: Obvious light leakage was confirmed after 80°C x 500 hours.

[0190] In addition, the results of the light leakage test in Table 1 were evaluated according to the above criteria Figure 1 A~​​​​​​​​Figure 1 The results of the light leakage of each of the polarizing plates of the shapes shown in C are summarized according to the following criteria.

[0191] ◎: All of the three polarizing plates used were evaluated as "good".

[0192] O: None of the three polarizing plates used was evaluated as "not good", but there was more than one evaluation of "good".

[0193] X: One of the three polarizing plates used was evaluated as "not good".

[0194] [Examples 2 to 3, Comparative Example 1]

[0195] Except that the acrylic polymer was synthesized using the monomer components described in Table 1 and the adhesive composition was obtained using the crosslinking agent described in Table 1, the same procedure as in Example 1 was followed to obtain the evaluation adhesive layer and the polarizing plate with adhesive layer. The same evaluation as in Example 1 was performed using the obtained evaluation adhesive layer and the polarizing plate with adhesive layer. The results are shown in Table 1.

[0196] Further, "L-45" in Table 1 is an isocyanate-based crosslinking agent manufactured by Synthesis Chemical Co., Ltd.

[0197] Figure 3 The light leakage of the polarizing plate with adhesive layer obtained in Comparative Example 1 was shown, and the initial and the light leakage after 80°C x 500 hours in the case where the polarizing plate in which the shape of the main surface was a circular shape (the shape shown in A-1 and A-2 of Figure 1 Figure 3 the case where the shape of the main surface was a shape having a notch (recess) (the shape shown in C of Figure 1 Figure 3 the case where the shape of the main surface was a shape having a notch (recess) (the shape shown in C of Figure 1 Figure 3 the case where the shape of the main surface was a shape having a notch (recess) (the shape shown in C of

[0198] [Table 1]

[0199]

[0200] [Reference Example]

[0201] In Example 1 and Comparative Example 1, the initial and the light leakage after 80°C x 500 hours in the case where the polarizing plate in which the shape of the main surface was a rectangular shape (the shape shown in D of Figure 1 the case where the shape of the main surface was a shape having a notch (recess) (the shape shown in C of​​​

[0202] The light leakage at the initial stage and after 80°C x 500 hours in the case of using the adhesive layer obtained in Example 1 was as shown in D-1 and D-2 of Table 1, respectively. Figure 4 The light leakage at the initial stage and after 80°C x 500 hours in the case of using the adhesive layer obtained in Comparative Example 1 was as shown in D'-1 and D'-2 of Table 1, respectively. Figure 4

[0203] As is clear from Table 1, Figure 2 and Figure 3 by using the present adhesive layer, light leakage can be suppressed for the first time in the case of using a shaped polarizing plate.

[0204] In addition, as is clear from Table 1, Figure 4 the present adhesive layer can suppress light leakage even in the case of using a non-shaped (the shape of the main surface is a square or a rectangle) polarizing plate, and is therefore applicable to such a polarizing plate, but as is clear from Table 1, Figure 4 in the case of using a non-shaped (the shape of the main surface is a square or a rectangle) polarizing plate, the light leakage phenomenon itself is not likely to occur.

[0205] In summary, the present application can suppress light leakage which is particularly likely to occur in a shaped polarizing plate, and from this point of view, it is an application which is specifically for a shaped polarizing plate.​

Claims

1. A shaped polarizing plate with an adhesive layer, which has an adhesive layer on at least one side of a shaped polarizing plate having a film on both sides of a polarizing sheet, the shaped polarizing plate is a polarizing plate whose main surface has a shape of a circle, a shape with a hole portion, or a shape with a recess portion, the adhesive layer satisfies the following requirement (I) or (II): Requirement (I): the storage modulus of the adhesive layer at 80°C is 2.0 x 10 4 ~ 1.0 x 10 5 Pa, Requirement (II): the gel fraction of the adhesive layer is 10 to 50 mass%, The optical elastic coefficient of the adhesive layer is -400 x 10 -12 ~ -50 x 10 -12 m 2 / N, the adhesive layer is a layer formed from an adhesive composition containing a (meth)acrylic polymer, an isocyanate-based crosslinking agent, and a silane coupling agent, the isocyanate-based crosslinking agent is selected from the group consisting of m-xylylene diisocyanate, toluene diisocyanate, chlorophenyl diisocyanate, diphenylmethane diisocyanate, o-xylylene diisocyanate, a reaction product containing an isocyanate group obtained by reacting these isocyanate compounds with a dihydric or higher alcohol, and an isocyanurate of isocyanate, the content of the isocyanate-based crosslinking agent is 0.02 to 1 parts by mass with respect to 100 parts by mass of the (meth)acrylic polymer.

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