Polarizing plate and optical display device including the same

Abstract

A polarizing plate and an optical display device including the polarizing plate are provided. The polarizing plate includes: a polarizer; a protective coating formed on the top surface of the polarizer; and a protective layer and an adhesive layer formed sequentially from the polarizer on the bottom surface of the polarizer, wherein the protective coating is formed of a thermosetting composition, and the modulus of the polarizing plate, as measured by a microhardness indenter located on the protective coating side, is approximately 10 MPa or greater than 10 MPa.

Description

Technical Field

[0001] The present invention relates to a polarizing plate and an optical display device including the polarizing plate. Background Technology

[0002] Optical display devices include polarizing plates for improving light efficiency and display quality. The polarizing plate includes a polarizer and a protective film formed on at least one surface of the polarizer. The polarizing plate can be bonded to an adhesive after an adhesive composition is applied to one surface of the protective film or after laminating an adhesive film formed from the adhesive composition.

[0003] Following the recent trend towards thinner optical display devices, there is also a trend towards reducing the thickness of polarizing plates. Various methods can be considered to reduce the thickness of polarizing plates, and recently, the use of a protective coating instead of a protective film as the protective layer for the polarizer has been explored. Meanwhile, polarizing plates (especially viewer-side polarizing plates) may be easily exposed to external ultraviolet light, and ultraviolet light incident on the polarizing plate can damage the adhesives used in polarizing plates, such as those in liquid crystal panels or organic light-emitting diode (OLED) panels. Therefore, it is necessary to achieve both thickness reduction and ultraviolet (UV) blocking effects.

[0004] Protective coatings can reduce the thickness of polarizing plates. However, due to differences in thickness and physical properties between the protective layer laminated on the upper surface and the protective layer laminated on the lower surface of the polarizer, the polarizing plate can warp. Furthermore, since the protective coating is formed directly on the polarizer, it is necessary to prevent the polarizer from cracking under reliable conditions such as thermal shock.

[0005] The background technology of the present invention is disclosed in Japanese Patent Application No. 2013-072951, etc. Summary of the Invention

[0006] Technical issues

[0007] This invention relates to a polarizing plate with a thickness reduction effect.

[0008] The present invention also relates to providing a polarizing plate that minimizes UV damage to polarizers and adhesives (e.g., the display panel of the polarizing plate) by including a relatively excessive amount of UV absorber in the protective coating.

[0009] The present invention also relates to providing a polarizing plate that provides a blocking effect for a polarizer and suppresses warping of the polarizing plate.

[0010] Technical solutions

[0011] One aspect of the present invention provides a polarizing plate.

[0012] 1. A polarizing plate comprising: a polarizer; a protective coating formed on an upper surface of the polarizer; and a protective layer and an adhesive layer formed sequentially from the polarizer on a lower surface of the polarizer, wherein the protective coating is formed of a thermosetting composition, and the polarizing plate has a modulus of about 10 MPa or greater than 10 MPa as measured using a microindenter on one surface of the protective coating.

[0013] 2. According to 1, the protective coating can be formed directly on the upper surface of the polarizer.

[0014] 3. According to 1 or 2, a protective coating may be laminated on the upper surface of the polarizer as a protective layer for the polarizer.

[0015] 4. According to any one of 1 to 3, the thermosetting composition may contain an adhesive resin, an isocyanate-based curing agent, and a UV absorber.

[0016] 5. According to 4, the UV absorber may be included in an amount of about 0.1 parts by weight to about 10 parts by weight relative to 100 parts by weight of adhesive resin.

[0017] 6. According to 4, UV absorbers may have a maximum absorption wavelength of about 390 nm or greater than 390 nm.

[0018] 7. According to 4, UV absorbers may include one or more of indole-based absorbers and triazine-based absorbers.

[0019] 8. According to any one of 1 to 7, the adhesive resin may comprise a (meth)acrylic acid copolymer comprising a monomer mixture comprising an alkyl (meth)acrylic acid monomer and a hydroxyl (meth)acrylic acid monomer, wherein at least one of the monomers contained in the monomer mixture is a monomer whose homopolymer has a glass transition temperature of about 50°C or greater than 50°C.

[0020] 9. According to 8, monomers whose homopolymers have a glass transition temperature of about 50°C or greater may be included in the monomer mixture in an amount of about 1 wt% to about 60 wt%.

[0021] 10. According to 8 or 9, monomers whose homopolymers have a glass transition temperature of about 50°C or greater may include one or more of methyl methacrylate, tert-butyl methacrylate, isopropyl methacrylate, sec-butyl methacrylate, and isobornyl methacrylate.

[0022] 11. According to any one of 8 to 10, the monomer mixture may contain about 85 wt% to about 99.9 wt% of an alkyl-based (meth)acrylic acid monomer and about 0.1 wt% to about 15 wt% of a hydroxyl-based (meth)acrylic acid monomer.

[0023] 12. According to any one of 8 to 11, the monomer mixture may also contain monomers having a carboxylic acid group.

[0024] 13. According to any one of 8 to 12, the monomer mixture may contain about 70 wt% to about 98 wt% of an alkyl (meth)acrylic acid monomer, about 0.1 wt% to about 15 wt% of a hydroxyl (meth)acrylic acid monomer, and about 0.1 wt% to about 15 wt% of a carboxylic acid monomer.

[0025] 14. According to any one of 1 to 13, the isocyanate-based curing agent may include a polyisocyanate-based curing agent containing a plurality of units, wherein said unit contains a urethane bond and an alkylene group having two or more carbon atoms.

[0026] 15. According to any one of 1 to 14, the isocyanate-based curing agent may include a polyisocyanate curing agent having a plurality of units, wherein said unit is represented by the following chemical formula 1:

[0027] [Chemical Formula 1]

[0028] *-R 1 -O-(C=O)NH-R 2 -NCO

[0029] (In chemical formula 1, * represents a binding site, and)

[0030] R 1 With R 2 (Same or different, and both are C2 to C20 divalent aliphatic hydrocarbon groups).

[0031] 16. According to any one of 1 to 15, it may contain 100 parts by weight of adhesive resin, about 10 parts by weight to about 40 parts by weight of isocyanate-based curing agent, and about 0.1 parts by weight to about 10 parts by weight of UV absorber.

[0032] 17. According to any one of 1 to 16, the polarizing plate may have a light transmittance of about 3% or less at a wavelength of 380 nm or 405 nm.

[0033] Another aspect of the present invention provides an optical display device.

[0034] 18. An optical display device comprising a polarizing plate according to the present invention.

[0035] 19. According to 18, the optical display device may include a polarizing plate, a transparent adhesive film laminated on the upper surface of the polarizing plate, and an organic light-emitting diode panel formed on the lower surface of the polarizing plate.

[0036] 20. According to 19, a cover glass may also be laminated on the upper surface of the transparent adhesive film.

[0037] Beneficial effects

[0038] This invention provides a polarizing plate with a thickness reduction effect.

[0039] The present invention provides a polarizing plate that minimizes UV damage to polarizers and adhesives (e.g., display panels of the polarizing plate) by including a relatively excessive amount of UV absorber in a protective coating.

[0040] The present invention provides a polarizing plate that provides a blocking effect for a polarizer and suppresses warping of the polarizing plate. Attached Figure Description

[0041] Figure 1 This is a cross-sectional view of a polarizing plate according to an embodiment of the present invention. Detailed Implementation

[0042] In the following sections, embodiments of the present application will be described in more detail with reference to the accompanying drawings. However, the technology disclosed in this application is not limited to the embodiments set forth herein, but may be implemented in other forms. Specifically, the embodiments described herein are provided so that this disclosure will be thorough and complete, and will fully convey the spirit of the present application to those skilled in the art.

[0043] In the accompanying drawings, the dimensions (e.g., width or thickness) of the components are slightly enlarged for clarity of illustration, and this is not limited to the scope of the invention. In several figures, the same reference numerals indicate substantially the same components.

[0044] In this specification, "upper portion" and "lower portion" are defined based on the accompanying drawings. Depending on the viewing angle, "upper portion" may be changed to "lower portion," and "lower portion" may be changed to "upper portion." When an element is referred to as being formed "on" another element, it means that the element can be formed directly on the other element, or that there may be intermediate elements. Conversely, when an element is referred to as being formed "directly" on or "directly" formed, it means that no other structure, such as an intermediate body, is involved.

[0045] In this specification, the “modulus” of a polarizing plate measured on one surface of the protective coating refers to the modulus of elasticity.

[0046] In this specification, "(meth)acrylic acid" refers to acryl and / or methacryl.

[0047] In this specification, "weight-average molecular weight" may be a value converted relative to polystyrene in gel permeation chromatography.

[0048] In this specification, the term "substituted or unsubstituted" means that one or more hydrogen atoms in a functional group are replaced by an ester group, a C1 to C10 alkyl group, a C2 to C10 alkenyl group, a C2 to C10 alkynyl group, a hydroxyl group, or a similar group having a C1 to C10 alkyl group.

[0049] In this specification, when describing a numerical range, "X to Y" means above X and below Y (X ≤ numerical value ≤ Y).

[0050] The polarizing plate according to the invention provides a thickness reduction effect by forming a protective coating on one surface of the polarizer instead of a protective layer. Since the polarizing plate according to the invention can form a protective coating using a thermocurable composition, and this protective coating contains a relatively excessive amount of UV absorber, and can be formed on the outermost surface of the polarizer where external light is incident, UV damage to the polarizer and adhesives (e.g., the display panel of the polarizing plate) can be minimized compared to polarizing plates having a protective coating formed from a photocurable composition. By having a modulus of about 10 MPa or greater measured using a microhardness indenter on one surface of the protective coating, the polarizing plate according to the invention provides both a blocking effect on the polarizer and an effect of suppressing warping of the polarizing plate.

[0051] The polarizing plate according to the present invention comprises: a polarizer; a protective coating formed on an upper surface of the polarizer; and a protective layer and an adhesive layer formed sequentially from the polarizer on a lower surface of the polarizer, wherein the protective coating is formed of a thermosetting composition, and the polarizing plate has a modulus of 10 MPa or greater than 10 MPa as measured using a microhardness indenter on one surface of the protective coating.

[0052] In the following text, reference will be made to Figure 1 The polarizing plate according to an embodiment of the present invention will be described.

[0053] Reference Figure 1 The polarizing plate includes a polarizer 100, a protective coating 200 formed on the upper surface of the polarizer 100, and a protective layer 300 and an adhesive layer 400 formed on the lower surface of the polarizer 100.

[0054] The polarizing plate has a modulus of approximately 10 MPa or greater, measured using a microhardness indenter on one surface of the protective coating. Within this range, it provides a blocking effect for the polarizer, thus suppressing polarizer breakage due to thermal shock and preventing warping. In this invention, since the protective coating is formed directly on the polarizer, and the modulus measured using a microhardness indenter on one surface of the protective coating is adjusted to approximately 10 MPa or greater, polarizer breakage due to thermal shock is suppressed, the likelihood of decolorization of dichroic dyes containing iodine or the like in the polarizer is reduced, and warping of the polarizing plate caused by the thickness difference between the protective coating formed on the upper surface of the polarizer and the protective and adhesive layers formed on the lower surface of the polarizer is suppressed.

[0055] Specifically, the modulus can be, for example, 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa, 15 MPa, 16 MPa, 17 MPa, 18 MPa, 19 MPa, 20 MPa, 21 MPa, 22 MPa, 23 MPa, 24 MPa, 25 MPa, 26 MPa, 27 MPa, 28 MPa, 29 MPa, 30 MPa, 31 MPa, 32 MPa, 33 MPa, 34 MPa, 35 MPa, 36 MPa, 37 MPa, 38 MPa, 39 MPa, or 40 MPa, specifically from about 10 MPa to about 40 MPa, and more specifically from about 10 MPa to about 30 MPa.

[0056] Protective coating

[0057] The protective coating 200 can be positioned on the portion of the polarizer where external light is first incident. In other words, the protective coating 200, as a protective layer, can be laminated only onto the upper surface of the polarizer 100. Therefore, as described below, by including a UV absorber, the protective coating effectively blocks ultraviolet light from the external light, and thus protects against UV damage to the polarizer and adhesives of the polarizer.

[0058] The protective coating 200 can be formed directly on the upper surface of the polarizer 100. "Directly formed" means that no adhesive layer is sandwiched between the protective coating and the polarizer.

[0059] The protective coating 200 may have a thickness of approximately 15 μm or less, and more specifically, greater than 0 μm but less than 15 μm. Within this range, the thickness of the polarizing plate can be reduced.

[0060] Due to its optical transparency, the protective coating 200 can have a total transmittance of about 90% or greater, and specifically about 90% to about 100%, in the visible light region (e.g., at a wavelength of 550 nm). Within the aforementioned range, the protective coating can be used in a polarizing plate without affecting the light emitted from the polarizing plate.

[0061] The protective coating 200 can be formed from a thermocurable composition comprising an adhesive resin, an isocyanate-based curing agent, and a UV absorber. Because the protective coating is formed from a thermocurable composition, it can contain a relatively excessive amount of UV absorber, and thus minimize UV ​​damage to the polarizer of the polarizing plate and the adhesives (e.g., the display panel).

[0062] The adhesive resin can increase the modulus of the polarizer when measured on one surface of the protective coating using a microhardness indenter, and improve the adhesion to the polarizer.

[0063] The adhesive resin may be a copolymer of (meth)acrylic acid, comprising a mixture of (meth)acrylic acid monomers having alkyl groups and (meth)acrylic acid monomers having hydroxyl groups, wherein at least one of the monomers contained in the monomer mixture is a monomer whose homopolymer has a glass transition temperature of about 50°C or greater than 50°C.

[0064] Since at least one of the monomers contained in the monomer mixture is a monomer whose homopolymer has a glass transition temperature of about 50°C or greater, the modulus of the polarizing plate measured on one surface of the protective coating using a microhardness indenter can reach the modulus range of the present invention. Specifically, the monomer mixture may include monomers whose homopolymers have glass transition temperatures, for example, about 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, for example, from about 50°C to about 200°C, and more specifically from about 80°C to about 150°C.

[0065] In monomer mixtures, from about 1 wt% to about 60 wt%, for example 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt% can be used. The amounts of 38wt%, 39wt%, 40wt%, 41wt%, 42wt%, 43wt%, 44wt%, 45wt%, 46wt%, 47wt%, 48wt%, 49wt%, 50wt%, 51wt%, 52wt%, 53wt%, 54wt%, 55wt%, 56wt%, 57wt%, 58wt%, 59wt%, 60wt%, specifically about 10wt% to about 60wt%, about 20wt% to about 60wt%, about 30wt% to about 60wt%, and more specifically about 40wt% to about 50wt% comprise monomers whose homopolymer has a glass transition temperature of about 50°C or greater. Within the above ranges, it can help to make the modulus of the polarizing plate measured using a microhardness indenter on one surface of the protective coating reach the modulus range of the present invention.

[0066] Alkyl (meth)acrylate monomers may include one or more of (meth)acrylates having substituted or unsubstituted C1 to C20 alkyl groups. For example, alkyl (meth)acrylate monomers may include one or more of methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, and isobornyl (meth)acrylate, but the invention is not limited thereto.

[0067] Among alkyl-containing (meth)acrylic monomers, monomers whose homopolymers have a glass transition temperature of about 50°C or greater can be selected and used by referring to product catalogs. For example, monomers among alkyl-containing (meth)acrylic monomers whose homopolymers have a glass transition temperature of about 50°C or greater may include one or more of methyl methacrylate, tert-butyl methacrylate, isopropyl methacrylate, sec-butyl methacrylate, and isobornyl methacrylate, but the invention is not limited thereto.

[0068] Hydroxyl-containing (meth)acrylic acid monomers may include one or more of the following: hydroxyl-containing (meth)acrylic acid monomers having substituted or unsubstituted C1 to C20 alkyl groups; hydroxyl-containing (meth)acrylic acid monomers having substituted or unsubstituted C3 to C20 alicyclic groups; and hydroxyl-containing (meth)acrylic acid monomers having substituted or unsubstituted C6 to C20 aromatic groups. For example, hydroxyl-containing (meth)acrylic acid monomers may include one or more of 2-hydroxyethyl (meth)acrylic acid, 2-hydroxypropyl (meth)acrylic acid, 2-hydroxybutyl (meth)acrylic acid, 4-hydroxybutyl (meth)acrylic acid, 6-hydroxyhexyl (meth)acrylic acid, 1,4-cyclohexanediol mono(meth)acrylic acid, 1-chloro-2-hydroxypropyl (meth)acrylic acid, diethylene glycol mono(meth)acrylic acid, 2-hydroxy-3-phenoxypropyl (meth)acrylic acid, 4-hydroxycyclopentyl (meth)acrylic acid, and 4-hydroxycyclohexyl (meth)acrylic acid.

[0069] For example, monomers having hydroxyl groups may include one or more monomers whose homopolymers have a glass transition temperature of about 20°C or greater, but the invention is not limited thereto. For example, monomers having hydroxyl groups may include one or more monomers whose homopolymers have a glass transition temperature of about 20°C or greater, such as about 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, and more specifically about 20°C to about 80°C. Among the monomers having hydroxyl groups, monomers whose homopolymers have a glass transition temperature of about 20°C or greater may include 2-hydroxyethyl methacrylate, etc., but the invention is not limited thereto.

[0070] The monomer mixture may also contain monomers having a carboxylic acid group. Monomers having a carboxylic acid group may include (meth)acrylic acid, fumaric acid, itaconic acid, etc., but the invention is not limited thereto.

[0071] In the embodiments, the monomer mixture may comprise from about 85 wt% to about 99.9 wt%, such as 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, 99.9 wt%, and specifically from about 90 wt% to about 95 wt% of alkyl-containing (meth)acrylic acid monomers, and from about 0.1 wt% to about 15 wt%, such as 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, and specifically from about 1 wt% to about 10 wt% of hydroxyl-containing (meth)acrylic acid monomers. Within the above range, the modulus and degree of curing can be adjusted to exhibit barrier properties.

[0072] In another embodiment, the monomer mixture may comprise: about 70 wt% to about 98 wt%, for example 70 wt%, 71 wt%, 72 wt%, 73 wt%, 74 wt%, 75 wt%, 76 wt%, 77 wt%, 78 wt%, 79 wt%, 80 wt%, 81 wt%, 82 wt%, 83 wt%, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt%, 96 wt%, 97 wt%, 98 wt%, and specifically about 85 wt% to about 90 wt% of alkyl-containing (meth)acrylic acid monomers; and about 0.1 wt% to about 15 wt%, for example 0.1 wt%. The monomer comprises, for example, 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, and specifically about 1 wt% to about 10 wt% of hydroxyl-containing (meth)acrylic acid monomers; and about 0.1 wt% to about 15 wt%, such as 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, and specifically about 1 wt% to about 10 wt% of carboxylic acid-containing monomers. Within the above range, curing properties are further imparted, and thus modulus properties can be improved.

[0073] The monomer mixture may also contain one or more of (meth)acrylamide, acrylonitrile, benzyl methacrylate, cyclohexyl methacrylate, N,N-dimethylacrylamide, styrene, and dihydrodicyclopentadienyl acrylate (DCPA) as monomers whose homopolymers have a glass transition temperature of about 50°C or greater than 50°C, but the invention is not limited thereto.

[0074] (Meth)acrylic acid copolymers can be prepared by polymerizing a monomer mixture using typical polymerization methods. These polymerization methods may include typical methods known to those skilled in the art. For example, (meth)acrylic acid copolymers can be prepared by adding an initiator to the monomer mixture and then performing typical copolymerization (e.g., suspension polymerization, emulsion polymerization, solution polymerization, etc.). The polymerization temperature can be from 60°C to 70°C, and the polymerization time can be from 6 hours to 8 hours. Typical initiators (e.g., azo polymerization initiators), peroxide polymerization initiators (e.g., benzoyl peroxide or acetyl peroxide), etc., can be used as initiators.

[0075] The adhesive resin (specifically, a (meth)acrylic acid copolymer) may have a weight-average molecular weight of about 200,000 or greater, for example, 200,000, 250,000, 300,000, 350,000, 400,000, 450,000, 500,000, 550,000, 600,000, 650,000, 700,000, 750,000, 800,000, 850,000, 900,000, 950,000, 1,000,000, specifically from 200,000 to 1,000,000, and more specifically from 100,000 to 300,000. Within the above ranges, the effects of the present invention can be readily achieved.

[0076] Isocyanate-based curing agents can improve the crosslinking degree of the protective coating and increase its adhesion to the polarizer by curing the adhesive resin. Isocyanate-based curing agents are thermosetting agents, and the adhesive resin is thermoset to form the protective coating. As described above, even when the protective coating of the present invention contains an excessive amount of UV absorber (described below) formed from a thermosetting composition, the protective coating can be implemented without any problems regarding its crosslinking degree.

[0077] Relative to 100 parts by weight of the adhesive resin, an isocyanate-based curing agent may be included in an amount ranging from about 10 parts by weight to about 40 parts by weight, for example, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, 36 parts by weight, 37 parts by weight, 38 parts by weight, 39 parts by weight, 40 parts by weight, and more specifically, about 15 parts by weight to about 30 parts by weight. Within the above range, the crosslinking degree and adhesion of the protective coating can be improved, and the flexibility can be increased.

[0078] Isocyanate-based curing agents may include polyisocyanate-based curing agents containing multiple units, wherein said units contain a urethane bond and an alkylene group having two or more carbon atoms. Polyisocyanate-based curing agents can help achieve a modulus within the modulus range of the present invention by curing the adhesive resin. "alkylene" may refer to C6 to C20 straight-chain alkylene groups, such as hexamethylene, dodecamethyl, trimethylhexamethylene, or similar groups, but the invention is not limited thereto.

[0079] In embodiments, the isocyanate-based curing agent may include an adduct of a polyisocyanate curing agent containing multiple units, said multiple units comprising a urethane-modified linear alkylene group having two or more carbon atoms. For example, the polyisocyanate-based curing agent may be an aliphatic polyisocyanate containing urethane. In this case, the aliphatic polyisocyanate curing agent may be a C4 to C20 diisocyanate, such as tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethyl diisocyanate, trimethylhexamethylene diisocyanate including 2,2,4-trimethylhexamethylene diisocyanate, etc. Commercially available products may be used as urethane-modified polyisocyanate-based curing agents.

[0080] In embodiments, the isocyanate-based curing agent may include a polyisocyanate curing agent having units represented by the following chemical formula 1. The curing agent preferably has multiple units, wherein said units are represented by the following chemical formula 1.

[0081] [Chemical Formula 1]

[0082] *-R 1 -O-(C=O)NH-R 2 -NCO

[0083] (In chemical formula 1, * represents a binding site, and)

[0084] R 1With R 2 (The groups may be the same or different, and are C2 to C20 divalent aliphatic hydrocarbon groups.) Aliphatic hydrocarbon groups may be straight-chain alkylene groups.

[0085] As a curing agent, a curing agent synthesized by a method known to those skilled in the art or a commercially available product can be used, such as AE 700-100 (Asahi Kasei Corporation).

[0086] The UV absorber contained in the protective coating can block UV damage to the polarizer and adhesives (e.g., display panel) of the polarizer by reducing the amount of ultraviolet light incident on the polarizer from external light.

[0087] UV absorbers may have a maximum absorption wavelength of about 390 nm or greater, specifically about 390 nm or greater and about 400 nm or less, and more specifically about 390 nm or greater and about 400 nm or less. Within the above range, UV transmittance is reduced by fully absorbing light with wavelengths of 420 nm or less, 400 nm to 420 nm, or 405 nm or less from external light, and thus damage to the polarizer and adhesive of the polarizing plate can be prevented.

[0088] "Maximum absorption wavelength" refers to the wavelength at which the maximum absorption peak is observed, that is, the wavelength at which the maximum absorbance is observed in the absorbance curve. "Absorbance" can be measured using typical methods known to those skilled in the art.

[0089] Therefore, the polarizing plate can have a light transmittance of about 3% or less, specifically about 0% to about 3%, at a wavelength of 380 nm, or about 3% or less, specifically about 0% to about 3%, at a wavelength of 405 nm. Specifically, since the polarizing plate of the present invention has a light transmittance of about 3% or less at a wavelength of 380 nm, it can also block UV damage to the polarizer.

[0090] In the embodiments, the UV absorber may include an absorber having a melting point of about 100°C or greater than 100°C, and more specifically about 140°C to about 220°C, and being a solid phase at room temperature.

[0091] UV absorbers may include one or more of indole-based and triazine-based absorbers having the aforementioned maximum absorption wavelength. In embodiments, the indole-based absorber may comprise a compound represented by the following chemical formula 2:

[0092] [Chemical Formula 2]

[0093]

[0094] (In chemical formula 2, R) 1 It is hydrogen or a substituted or unsubstituted C1 to C10 alkyl group.

[0095] R 2 It is hydrogen or a substituted or unsubstituted C6 to C20 aryl group.

[0096] R 3 It is hydrogen or a substituted or unsubstituted C1 to C10 alkyl group.

[0097] R 4 It is hydrogen, cyano (CN), or a substituted or unsubstituted C1 to C10 alkyl group, and

[0098] R 5 It is cyano or -(C=O)OR 6 (Here, R) 6 It can be a substituted or unsubstituted C1 to C10 alkyl group, or a substituted or unsubstituted C6 to C20 aryl group.

[0099] Specifically, R 1 It is a C1 to C5 alkyl group, specifically a methyl group, R 2 It is a C6 to C10 aryl group, specifically a phenyl group, R 3 It is hydrogen or C1 to C5 alkyl, specifically hydrogen, R 4 It is cyano, and R 5 It is cyano or -(C=O)-OR 6 (Here, R) 6 (These are substituted or unsubstituted C1 to C5 alkyl groups). More specifically, compounds represented by Formula 2 may include compounds represented by Formula 2-1 or Formula 2-2:

[0100] [Chemical Formula 2-1]

[0101]

[0102] [Chemical Formula 2-2]

[0103]

[0104] In the embodiments, the triazine absorbent may comprise a compound represented by the following chemical formula 3:

[0105] [Chemical Formula 3]

[0106]

[0107] (in chemical formula 3,

[0108] R 1 R 2 and R3 Each can be a substituted or unsubstituted hydroxyphenyl group.

[0109] Relative to 100 parts by weight of the adhesive resin, the UV absorber may be included in an amount from about 0.1 parts by weight to about 10 parts by weight, for example, 0.1 parts by weight, 0.5 parts by weight, 1 part by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, 4.5 parts by weight, 5 parts by weight, 5.5 parts by weight, 6 parts by weight, 6.5 parts by weight, 7 parts by weight, 7.5 parts by weight, 8 parts by weight, 8.5 parts by weight, 9 parts by weight, 9.5 parts by weight, 10 parts by weight, and specifically about 1 part by weight to about 5 parts by weight. Within the above range, a UV blocking effect can be achieved, and there is no problem, such as the UV absorber leaching out of the protective coating.

[0110] In addition to isocyanate-based curing agents, the composition may also contain typical thermosetting agents known to those skilled in the art.

[0111] For example, the thermosetting agent may include one or more of carbodiimide-based curing agents, metal chelate-based curing agents, aziridine-based curing agents, and epoxy resin-based curing agents. The thermosetting agent may be contained in an amount from about 0.001 parts by weight to about 5 parts by weight, for example, from about 0.01 parts by weight to about 1 part by weight, relative to 100 parts by weight of the adhesive resin. Within the above range, it can help form a protective coating.

[0112] The composition may also contain a silane coupling agent.

[0113] Silane coupling agents can increase the adhesion of the protective coating to the polarizer. Silane coupling agents may include typical silane coupling agents known to those skilled in the art. For example, silane coupling agents may include epoxy-containing silane coupling agents, such as glycidoxypropyltrimethoxysilane, glycidoxypropylmethyldimethoxysilane, etc., but the invention is not limited thereto.

[0114] The silane coupling agent may be included in an amount of about 0.01 parts by weight to about 5 parts by weight, for example, about 0.1 parts by weight to about 2.5 parts by weight, relative to 100 parts by weight of the adhesive resin. Within the above range, the adhesion to the polarizer can be increased.

[0115] The composition may further comprise a crosslinking catalyst. The crosslinking catalyst can increase the degree of crosslinking of the protective coating formed by the composition. The crosslinking catalyst may include one or more metals and metal-containing compounds. Specifically, the crosslinking catalyst may include one or more tin-containing compounds, zinc-containing compounds, titanium compounds, and bismuth compounds. More specifically, the crosslinking catalyst may include one or more dibutyltin dilaurate and tin dimaleate.

[0116] The crosslinking catalyst may be included in an amount of 0.01 to 1.5 parts by weight relative to 100 parts by weight of the adhesive resin. Within the above range, the degree of crosslinking can be increased, and moisture penetration can be inhibited.

[0117] The composition may also contain additives. Additives can provide additional functionality to the protective coating. Specifically, additives may include one or more of reaction inhibitors, adhesion enhancers, thixotropic agents, conductivity imparting agents, color control agents, stabilizers, antioxidants, and leveling agents, but the invention is not limited thereto.

[0118] The composition may also contain typical solvents to increase applicability. For example, the solvent may include ketone solvents, such as methyl ethyl ketone, isobutyl ketone, or similar solvents, but the invention is not limited thereto.

[0119] A protective coating 200 can be formed by applying the composition to a polarizer or release film to a predetermined thickness and performing thermosetting at 90°C to 100°C for 1 to 3 minutes.

[0120] polarizer

[0121] Polarizer 100 may include a polarizer formed from a polyvinyl alcohol-based resin film. Specifically, the polarizer may be a polyvinyl alcohol-based polarizer manufactured by adsorbing one or more of iodine and dichroic dyes onto the polyvinyl alcohol-based resin film, or a polyene-based polarizer manufactured by dehydrating the polyvinyl alcohol-based resin film.

[0122] The polarizer 100 may have a thickness of about 5 μm to about 30 μm, and more specifically about 5 μm to about 20 μm. Within the above range, the polarizer can be used in a polarizing plate and can achieve the effect of reducing the thickness of the polarizing plate.

[0123] protective layer

[0124] A protective layer 300 is formed on the lower surface of the polarizer 100 and protects the polarizer. The protective layer may include an optically transparent polymer film or liquid crystal layer.

[0125] In embodiments, the protective layer 300 may be an optically transparent resin film and may include one or more of the following: cellulose ester resins, such as triacetyl cellulose (TAC); cyclic polyolefin resins, such as cyclic olefin polymers (COP); (meth)acrylate resins; poly(meth)acrylate resins; polycarbonate (PC) resins; polyester resins, including polyethylene terephthalate (PET); polyethersulfone resins; polysulfone resins; polyamide resins; polyimide resins; noncyclic polyolefin resins; polyarylate resins; polyvinyl alcohol resins; polyvinyl chloride resins; polyvinylidene chloride resins; and acrylic resins.

[0126] Considering the function of the polarizer, the protective layer 300 may have a retardation within a predetermined range. For example, the protective layer 300 may have an in-plane retardation (Re) of about 100 nm to about 350 nm at a wavelength of 550 nm. The protective layer 300 may be a laminate of two or more protective layers having the above-mentioned in-plane retardation. In this specification, the "in-plane retardation (Re)" can be calculated by Re = (nx - ny) × d (where nx and ny are the refractive indices of the protective layer in the slow axis direction and the fast axis direction, respectively, and d is the thickness of the protective layer (unit: nm)).

[0127] The protective layer 300 may have a thickness greater or less than that of the protective coating. Specifically, the protective layer may have a thickness from about 0.1 μm to about 200 μm, more specifically from about 10 μm to about 150 μm, and more specifically from about 20 μm to about 100 μm. Within the above range, the protective layer may be used in a polarizing plate.

[0128] Despite Figure 1 Not shown, but the protective layer 300 can be bonded to the polarizer via an adhesive layer. For example, the adhesive layer can be formed of one or more of an aqueous adhesive and a photocurable adhesive. The adhesive layer can have a thickness of about 30 μm or less, for example, about greater than 0 μm and less than about 30 μm.

[0129] Adhesive layer

[0130] The adhesive layer 400 can be formed on the lower surface of the protective layer 300, and can enable the polarizing plate to be adhered to the adhesive.

[0131] The adhesive layer 400 may be formed from a composition for use as an adhesive layer, said composition comprising an adhesive resin, such as a (meth)acrylic adhesive resin, a silicone adhesive resin, a urethane adhesive resin, an epoxy adhesive resin, or a similar resin. Preferably, for ease of preparation, the adhesive layer 400 may be formed from a (meth)acrylic adhesive resin. The (meth)acrylic adhesive resin may include adhesive resins used in typical compositions known to those skilled in the art.

[0132] The adhesive layer 400 may have a thickness of about 5 μm to about 200 μm, specifically about 10 μm to about 150 μm, and more specifically about 20 μm to about 100 μm. Within the above range, the adhesive layer can be used in a polarizing plate.

[0133] The optical display device according to an embodiment of the present invention will be described below.

[0134] The optical display device includes the polarizing plate of the present invention. The optical display device may be a liquid crystal display device, an organic light-emitting display device, a flexible organic light-emitting display device, or a similar display device, but the present invention is not limited thereto.

[0135] In embodiments, the optical display device may include: a polarizing plate of the present invention; a transparent adhesive film (e.g., optically clear adhesive, OCA) laminated on the upper surface of the polarizing plate; and a panel, such as an OLED panel for an optical display device, formed on the lower surface of the polarizing plate.

[0136] In another embodiment, the optical display device may include: a polarizing plate of the present invention; a transparent adhesive film (e.g., OCA) laminated on the upper surface of the polarizing plate; a cover glass laminated on the upper surface of the transparent adhesive film; and a panel for the optical display device formed on the lower surface of the polarizing plate.

[0137] Methods of implementing the present invention

[0138] The configuration and operation of the present invention will be further described in detail below through examples of the invention. However, the following examples are provided to aid in understanding the present invention, and the scope of the present invention is not limited to these examples.

[0139] Preparation Example 1

[0140] A monomer mixture comprising 40 parts by weight of n-butyl acrylate, 5 parts by weight of 2-hydroxyethyl methacrylate, 50 parts by weight of methyl methacrylate, and 5 parts by weight of acrylic acid was fed into a 1L reactor equipped with a condenser for nitrogen reflux and easy temperature control, and 100 parts by weight of ethyl acetate was added as a solvent. Subsequently, to remove oxygen, nitrogen was introduced for 1 hour to purge the interior of the reactor, and the reactor temperature was maintained at 62°C. The monomer mixture was uniformly stirred, and then 0.03 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator, and the reaction was carried out for 8 hours to prepare a (meth)acrylic acid copolymer with a weight average molecular weight of 200,000.

[0141] Preparation Example 2

[0142] A monomer mixture comprising 90 parts by weight of n-butyl acrylate, 5 parts by weight of 4-hydroxybutyl acrylate, and 5 parts by weight of acrylic acid was fed into a 1L reactor equipped with a condenser for nitrogen reflux and easy temperature control, and 100 parts by weight of ethyl acetate was added as a solvent. Subsequently, to remove oxygen, nitrogen was introduced for 1 hour to purge the interior of the reactor, and the reactor temperature was maintained at 62°C. The monomer mixture was uniformly stirred, and then 0.03 parts by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator, and the reaction was carried out for 8 hours to prepare a (meth)acrylic acid copolymer with a weight average molecular weight of 200,000.

[0143] The details of the components used in the examples and comparative examples are as follows.

[0144] (A) Adhesive resin:

[0145] (A1) Preparation of the (meth)acrylic acid copolymer of Example 1

[0146] (A2) Preparation of the (meth)acrylic acid copolymer of Example 2

[0147] (B) Isocyanate-based curing agents:

[0148] (B1)AE 700-100 (Asahi Kasei Corporation, isocyanate-based curing agent)

[0149] (B2) Coronate L (a trimethylolpropane adduct of toluene diisocyanate from Nippon Polyurethane Co., Ltd.)

[0150] (C) UV absorber:

[0151] (C1)UV 3912 (Orient Chemical Industries, indole absorbent)

[0152] (C2) Tinuvin 477 (BASF, triazine absorbent)

[0153] (D) Silane coupling agent: KBM-403 (Shin-Etsu Silicones, 3-glycidoxypropyltrimethoxysilane)

[0154] Example 1

[0155] A polyvinyl alcohol (PVA) membrane (Kuraray, saponification value: 99.5 mol%, degree of polymerization: 2000, and thickness: 80 μm) washed with water was swollen in a swelling tank containing water at 30°C. The PVA membrane passing through the swelling tank was then treated in a dyeing tank at 30°C for 30 to 200 seconds, the dyeing tank containing an aqueous solution of 3 wt% potassium iodide. The PVA membrane passing through the dyeing tank was then passed through a wet crosslinking tank containing an aqueous solution at 30°C to 60°C, the aqueous solution containing 3 wt% boric acid. The PVA membrane passing through the crosslinking tank was stretched in an aqueous solution containing 3 wt% boric acid at 50°C to 60°C with a total stretch ratio of 6, thereby producing a polarizer (thickness: 20 μm).

[0156] Based on solids content, 100 parts by weight of the (meth)acrylic acid copolymer of Preparation Example 1, 30 parts by weight of (B1) isocyanate curing agent, 1.5 parts by weight of (C1) UV absorber, 0.1 parts by weight of (D) silane coupling agent and 20 parts by weight of methyl ethyl ketone solvent were mixed and stirred at 25°C for 5 minutes to prepare a composition for protective coating.

[0157] The prepared composition for the protective coating was applied to the upper surface of the manufactured polarizer to a predetermined thickness, treated at 90°C for 3 minutes to remove the solvent, and aged at 25°C for 72 hours to form a protective coating (thickness: 7 μm) on the upper surface of the polarizer.

[0158] A triacetyl cellulose membrane (Fujifilm, n-TAC, thickness: 80 μm), serving as a protective film, is bonded to the lower surface of the polarizer using an aqueous adhesive (containing a polyvinyl alcohol-based resin). An adhesive layer (thickness: 20 μm, (meth)acrylate adhesive layer) is formed on the other surface of the triacetyl cellulose membrane, thereby creating a polarizing plate in which a protective coating, a polarizer, an adhesive layer, a triacetyl cellulose membrane, and an adhesive layer are sequentially laminated. The adhesive layer is formed from a composition comprising a (meth)acrylate adhesive resin and an isocyanate-based curing agent.

[0159] Examples 2 to 5

[0160] The polarizing plate was manufactured in the same manner as in Example 1, except that the components and / or their contents (parts by weight) of the composition used for the protective coating were varied as shown in Table 1 below. In Table 1 below, "-" indicates that the corresponding component is not included.

[0161] Comparative Example 1 and Comparative Example 2

[0162] Except for changes to the components and / or their contents as shown in Table 1 below, an adhesive composition for a polarizing plate was prepared in the same manner as in Example 1.

[0163] The following physical properties of the polarizers of the examples and comparative examples were evaluated, and the results are shown in Table 1 below.

[0164] (1) Modulus (unit: MPa): The modulus of each polarizer of the examples and comparative examples was measured on one surface of the protective coating. The polarizers were cut into length × width (10 cm × 10 cm) to prepare samples. The adhesive layer of the sample was bonded to a glass plate to fix the sample on the glass plate. At 25°C, a constant force of 200 mN was applied to the protective coating of the sample for 5 seconds using a microhardness indenter (MicroIndenter, Hysitron TI 750 Ubi), held for 2 seconds, and relaxed for 5 seconds. The modulus was then calculated.

[0165] (2) Polarizer Cracks: Each polarizing plate (without cracks in the polarizer) of the examples and comparative examples was cut into length × width (10cm × 10cm). The adhesive layer of the polarizing plate was laminated onto a glass plate, and autoclaved at 50°C and 1 atmosphere to prepare a sample in which the polarizing plate was fixed to the glass plate. The sample was placed in a thermal shock chamber at -30°C for 30 minutes and then at 80°C for 30 minutes. This process was set as one cycle and repeated 200 times. After 200 cycles, the maximum length of the crack generated in the polarizer was measured. The crack formed in the longitudinal direction (machine direction, MD) of the polarizer. Cracks with a length of 4mm or less were evaluated as "Good (OK)" and cracks with a length greater than 4mm were evaluated as "Undesirable (NG)".

[0166] (3) Light transmittance of polarizing plate (unit: %): Using the adhesive layer of the polarizing plate as a medium, each polarizing plate of the example and comparative examples was bonded to a glass plate, and the light transmittance of the polarizing plate was measured using a V-7100 light transmittance analyzer (JASCO Japan). The light transmittance was measured at dual wavelengths of 380 nm and 405 nm.

[0167] (4) Viscosity (unit: gf): At 25°C, a probe (having a conical curved cross-section with a radius of 2.5 mm and formed of stainless steel (SUS)) was brought into contact with the protective coating of each polarizer of the examples and comparative examples for 10 seconds. The force applied to the probe as it detached from the protective coating was measured using a viscosity analyzer UTM (TA-Analyzer). Preferably, the obtained viscosity was 10 gf or less, for example, 0 gf to 10 gf.

[0168] (5) Warpage (unit: mm): Using the adhesive layer of the polarizing plate as a medium, each polarizing plate (MD of the polarizer × TD of the polarizer: 180mm × 110mm, rectangular) of the examples and comparative examples was bonded to a glass plate (width, length, and thickness: 190mm, 120mm, and 0.5T, rectangular) to prepare samples. The prepared samples were placed in an oven at 85°C and removed after 24 hours, and the warpage of the samples was measured. The samples were placed on a flat surface, a weight was placed on one edge, and the distance between the flat surface and the sample was measured at the diagonal edge. Cases where the distance between the flat surface and the sample was 0mm or greater than 0mm and 2mm or less than 2mm were evaluated as ○, cases where the distance was greater than 2mm and 5mm or less than 5mm were evaluated as △, and cases where the distance was greater than 5mm were evaluated as ×.

[0169] [Table 1]

[0170]

[0171] As shown in Table 1, the polarizing plate of the present invention provides a blocking effect on the polarizer and suppresses the warping of the polarizing plate.

[0172] On the other hand, the polarizing plate of the comparative example, whose modulus is outside the modulus range of the present invention, did not provide a blocking effect for the polarizer, showed no obvious warpage suppression effect, and exhibited poor adhesion.

[0173] It should be understood that those skilled in the art can readily make simple modifications or alterations to this invention, and all such modifications or alterations are covered within the scope of this invention.

Claims

1. A polarizing plate, comprising: polarizer; A protective coating is formed on the upper surface of the polarizer; as well as A protective layer and an adhesive layer are sequentially formed on the lower surface of the polarizer. The protective coating is formed from a thermosetting composition, and The polarizing plate has a modulus of 10 MPa or greater than 10 MPa, which can be measured using a microhardness indenter on one surface of the protective coating. The heat-curable composition comprises an adhesive resin, an isocyanate-based curing agent, and an ultraviolet absorber; The adhesive resin comprises a (meth)acrylic acid copolymer of a monomer mixture, the monomer mixture comprising (meth)acrylic acid monomers having alkyl groups and (meth)acrylic acid monomers having hydroxyl groups, and wherein at least one of the monomers contained in the monomer mixture is a monomer whose homopolymer has a glass transition temperature of 50°C or greater.

2. The polarizing plate according to claim 1, wherein the protective coating is formed directly on the upper surface of the polarizer.

3. The polarizing plate according to claim 1, wherein only the protective coating is laminated on the upper surface of the polarizer as a protective layer for the polarizer.

4. The polarizing plate according to claim 1, wherein the ultraviolet absorber is contained in an amount of 0.1 parts by weight to 10 parts by weight relative to 100 parts by weight of the adhesive resin.

5. The polarizing plate according to claim 3, wherein the ultraviolet absorber has a maximum absorption wavelength of 390 nm or greater than 390 nm.

6. The polarizing plate according to claim 3, wherein the ultraviolet absorber comprises one or more of an indole-based absorber and a triazine-based absorber.

7. The polarizing plate according to claim 1, wherein the monomer having a glass transition temperature of 50°C or greater is included in the monomer mixture in an amount of 1 wt% to 60 wt%.

8. The polarizing plate according to claim 1, wherein the monomer having a glass transition temperature of 50°C or greater than 50°C comprises one or more of methyl methacrylate, tert-butyl methacrylate, isopropyl methacrylate, sec-butyl methacrylate, and isobornyl methacrylate.

9. The polarizing plate according to claim 1, wherein the monomer mixture comprises 85 wt% to 99.9 wt% of the alkyl-containing (meth)acrylic acid monomer and 0.1 wt% to 15 wt% of the hydroxyl-containing (meth)acrylic acid monomer.

10. The polarizing plate according to claim 1, wherein the monomer mixture further comprises a monomer having a carboxylic acid group.

11. The polarizing plate of claim 10, wherein the monomer mixture comprises 70 wt% to 98 wt% of the alkyl-containing (meth)acrylic acid monomer, 0.1 wt% to 15 wt% of the hydroxyl-containing (meth)acrylic acid monomer, and 0.1 wt% to 15 wt% of the carboxylic acid monomer.

12. The polarizing plate according to claim 1, wherein the isocyanate-based curing agent comprises a polyisocyanate-based curing agent containing a plurality of units, wherein the units contain urethane bonds and alkylene groups having two or more carbon atoms.

13. The polarizing plate according to claim 12, wherein the isocyanate-based curing agent comprises a polyisocyanate curing agent having said plurality of units, wherein said unit is represented by the following chemical formula 1: [Chemical Formula 1] -R 1 -O-(C=O)NH-R 2 -NCO In Chemical Formula 1, denotes a binding site, and R1 and R2 may be the same or different, and are C2 to C20 divalent aliphatic hydrocarbon groups.

14. The polarizing plate according to claim 1, comprising 100 parts by weight of the adhesive resin, 10 to 40 parts by weight of the isocyanate-based curing agent, and 0.1 to 10 parts by weight of the ultraviolet absorber.

15. The polarizing plate according to claim 1, wherein the polarizing plate has a light transmittance of 3% or less at a wavelength of 380 nm or 405 nm.

16. An optical display device comprising a polarizing plate as claimed in any one of claims 1 to 15.

17. The optical display device according to claim 16, wherein the optical display device comprises the polarizing plate, a transparent adhesive film laminated on the upper surface of the polarizing plate, and an organic light-emitting diode panel formed on the lower surface of the polarizing plate.

18. The optical display device according to claim 17, wherein a protective glass is further laminated on the upper surface of the transparent adhesive film.

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