Polarizing plate and optical display device

Abstract

To provide a polarizing plate that does not include a protective layer on at least one surface of a polarizer and includes a barrier layer to prevent elution of a dichroic material from the polarizer when left under high-temperature high-humidity conditions for a prolonged period of time.SOLUTION: A polarizing plate provided herein includes a polarizer and a barrier layer laminated on one surface of the polarizer, the barrier layer comprising a cured product of a composition containing a polyvinyl alcohol resin, a crosslinking agent, and a water-based ionic material, where a content of the water-based ionic material in the barrier layer is 0.5-18 wt%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Light-emitting display devices, including organic light-emitting display devices, do not necessarily have to include a polarizing plate. However, incident external light may be totally reflected by the panel in the light-emitting display device, degrading the image quality. Therefore, light-emitting display devices generally include a polarizing plate on the upper surface of the panel. The polarizing plate is composed of a polarizer and a retardation film. The retardation film may be a polymer film, but due to the recent trend toward thinner displays, a liquid crystal film is now being used.

[0003] On the other hand, in recent years, due to the trend toward thinner polarizing plates, a method of laminating a barrier layer on a polarizing plate instead of a protective layer has been considered. The barrier layer is generally formed by coating and curing a barrier layer composition, and therefore can provide a thinner film than existing protective layers.

[0004] The background art of the present invention is disclosed in Korean Patent Publication No. 10-2006-0103451 and the like. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Korean Patent Publication No. 10-2006-0103451 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a polarizing plate that does not have a protective layer on at least one side of the polarizer and that has a barrier layer that prevents elution of a dichroic material from the polarizer after being left at high temperature and humidity for a long period of time. [Means for solving the problem]

[0007] One embodiment of the present disclosure is a polarizing plate.

[0008] In one embodiment, the polarizing plate includes a polarizer and a barrier layer laminated on one surface of the polarizer, the barrier layer including a cured product of a composition including a polyvinyl alcohol-based resin, a crosslinking agent, and a water-based ionic substance, and the water-based ionic substance is contained in the barrier layer in an amount of 0.5 wt % to 18 wt %.

[0009] Another embodiment is an optical display device.

[0010] The optical display device includes the polarizing plate of the present invention or the barrier layer of the present invention. [Effects of the Invention]

[0011] The present invention can provide a polarizing plate having a barrier layer that prevents elution of a dichroic material from the polarizer after being left at high temperature and high humidity for a long period of time without a protective layer on at least one side of the polarizer. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view of a polarizing plate according to one embodiment. [Figure 2] FIG. 10 is a cross-sectional view of a polarizing plate according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention may be embodied in various different forms and is not limited to the embodiments set forth herein, but may be practiced in a variety of ways, such as by way of example only, with reference to the accompanying drawings, in which:

[0014] In the drawings, parts that are not relevant to the description are omitted in order to clearly explain the present invention, and the same names are used for identical or similar components throughout the specification. The length and size of each component in the drawings are for the purpose of explaining the present invention, and the present invention is not limited to the length and size of each component shown in the drawings.

[0015] In this specification, "upper" and "lower" are defined based on the drawings, and "upper" may be changed to "lower" and "lower" to "upper" depending on the viewpoint, and "on" may include not only directly on but also the case where another structure is interposed between them. Meanwhile, "directly on" or "directly on" or "directly formed" indicates that there is no intervening structure such as an intermediate body.

[0016] The terms used herein are merely used to describe exemplary embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless otherwise clearly indicated in the context.

[0017] In this specification, when describing a range of values, "X to Y" means "at least X and at most Y" (X≦ and ≦Y).

[0018] The present invention relates to a polarizing plate having no protective layer on at least one side of a polarizer, and the polarizing plate has a barrier layer instead of the protective layer.

[0019] Here, the term "protective layer" refers to an optical element that is laminated on one side of a polarizer to protect the polarizer. The protective layer may be a film or a coating layer. The protective layer may be a liquid crystal layer or a non-liquid crystal layer. The protective layer may have an in-plane retardation within a predetermined range at a wavelength of 550 nm, or may have no in-plane retardation.

[0020] In one embodiment, the protective layer may include optically transparent protective films or protective coating layers commonly known to those skilled in the art. For example, the protective film may include one or more of cellulose ester-based resins such as triacetyl cellulose (TAC), cyclic polyolefin (COP)-based resins such as amorphous cyclic polyolefin, polycarbonate-based resins, polyester-based resins such as polyethylene terephthalate (PET), polyethersulfone-based resins, polysulfone-based resins, polyamide-based resins, polyimide-based resins, acyclic polyolefin-based resins, poly(meth)acrylate-based resins such as polymethyl methacrylate resin, polyvinyl alcohol-based resins, polyvinyl chloride-based resins, and polyvinylidene chloride-based resins.

[0021] In one embodiment, the barrier layer may be formed directly on the polarizer. Here, "directly formed" means that the barrier layer is formed on the polarizer without any adhesive or pressure-sensitive adhesive layer between the polarizer and the barrier layer. For example, the barrier layer may be formed by coating or applying the barrier layer composition described below directly onto one side of the polarizer, followed by drying and curing.

[0022] In one embodiment, the polarizing plate can include a polarizer, a protective layer laminated on one side of the polarizer, and a barrier layer laminated on another side of the polarizer.

[0023] As described below, the barrier layer can be formed by applying a barrier layer composition to one side of a polarizer and then curing it. Therefore, the barrier layer can be thin. Polarizers contain a dichroic material, such as iodine, to provide polarization performance. Therefore, if a polarizing plate is left at high temperature and humidity for a long period of time, the dichroic material, such as iodine, may leach out of the polarizer. The dichroic material leach out of the polarizer may pass through an optical element disposed between the polarizing plate and the optical display panel to which the polarizing plate is attached, thereby corroding the optical display panel, particularly the substrate. In one embodiment, the polarizing plate includes a barrier layer, as described below. The dichroic material leach out of the polarizer after long-term storage at high temperature and humidity cannot pass through the barrier layer, thereby preventing corrosion of the substrate. Whether the dichroic material leach out of the polarizer has passed through the barrier layer can be confirmed by a color change. The color change can be seen in the experimental examples below.

[0024] A polarizing plate according to one embodiment will be described below.

[0025] The polarizing plate includes a polarizer and a barrier layer laminated on one surface of the polarizer.

[0026] Barrier layer The barrier layer contains a cured product of a composition containing a polyvinyl alcohol resin, a crosslinking agent, and a water-based ionic substance, and the water-based ionic substance is contained in the barrier layer in an amount of 0.5% to 18% by weight.

[0027] The barrier layer comprises a cured product of the composition.

[0028] In one embodiment, the cured product may be a thermoset product. The barrier layer may be prepared by thermal curing, including heat treatment, without light irradiation. Alternatively, the barrier layer may include a UV absorber in any layer of the polarizing plate. When the polarizing plate is laminated on a light-emitting element display device, the UV absorber can prevent damage to the light-emitting element due to external light.

[0029] In one embodiment, the barrier layer may include a polyvinyl alcohol-based resin, a crosslinking agent, and a water-based ionic material, which may be derived from the composition.

[0030] The composition is an aqueous composition comprising a polyvinyl alcohol resin, a crosslinking agent, an aqueous ionic substance, and an aqueous solvent. The aqueous ionic substance is easily dissolved in the aqueous solvent, facilitating the formation of a barrier layer and preventing a dichroic substance eluted from a polarizer on the front surface of a polarizing plate from penetrating through the barrier layer.

[0031] The water-based ionic substance is contained in the barrier layer in an amount of 0.5 to 18% by weight. When the water-based ionic substance is contained in the barrier layer in an amount of 0.5% by weight or more, it is possible to prevent the dichroic substance eluted from the polarizer from penetrating the barrier layer and to prevent corrosion of the substrate when the polarizing plate is left at high temperature and high humidity for a long period of time. When the water-based ionic substance is contained in the barrier layer in an amount of 18% by weight or less, the problem of reduced light transmittance of the barrier layer due to the inclusion of an excessive amount of water-based ionic substance is avoided, and the barrier layer can be laminated to the polarizer with high adhesion.For example, water-based ionic substances are present in the barrier layer at 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.1, 8.1, 8.1, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10.1, 10. 2,5.3,5.4,5.5,5.6,5.7,5.8,5.9,6.0,6.1,6.2,6.3,6.4,6.5,6.6,6.7,6.8,6.9,7.0,7.1,7.2,7.3,7.4,7.5,7.6,7.7,7.8,7.9,8.0,8.1,8.2,8.3,8.4,8.5,8.6,8.7,8.8,8.9,9.0,9.1,9.2,9.3,9.4,9.5,9.6,9.7,9.8,9.9,10.0,10.1,10.2,10.3, 10.4,10.5,10.6,10.7,10.8,10.9,11.0,11.1,11.2,11.3,11.4,11.5,11.6,11.7,11.8,11.9,12.0,12.1,12.2,12.3,12.4,12.5,12.6,12.7,12.8,12.9,13.0,13.1,13.2,13.3,13.4,13.5,13.6,13.7,13.8,13.9,14.0,14.1,14.2,14.3,14.4,14.5, It may be included at 14.6, 14.7, 14.8, 14.9, 15.0, 15.1, 15.2, 15.3, 15.4, 15.5, 15.6, 15.7, 15.8, 15.9, 16.0, 16.1, 16.2, 16.3, 16.4, 16.5, 16.6, 16.7, 16.8, 16.9, 17.0, 17.1, 17.2, 17.3, 17.4, 17.5, 17.6, 17.7, 17.8, 17.9, 18.0% by weight, 0.8% to 17% by weight, or 0.9% to 17% by weight.

[0032] The water-based ionic substance not only dissolves well in the water-based solvent but also adsorbs the dichroic substance, particularly iodide ions, dissolved in the water-based solvent and leached from the polarizer, thereby ultimately preventing the dichroic substance from penetrating the barrier layer. Since the ionic substance is contained in the water-based composition for the barrier layer, it must be soluble in the water-based solvent. Furthermore, the ionic substance must be able to adsorb the leached dichroic substance, particularly iodide ions. Furthermore, the water-based ionic substance must not affect the curing reaction between the polyvinyl alcohol-based resin and the crosslinker, as described below.

[0033] The aqueous ionic substance is composed of cations and anions, and the cations can adsorb the iodide ions that have been dissolved.

[0034] In one embodiment, the water-based cationic material may be comprised of an ammonium-based cation and an anion.

[0035] In one embodiment, the ammonium-based cation may have an aliphatic or aromatic hydrocarbon group that has a hydroxyl group or is substituted with a hydroxyl group. This may facilitate adsorption of the eluted dichroic substance, particularly iodide ions. For example, the number of hydroxyl groups in the aqueous ionic substance may be one or more, for example, one to five.

[0036] In one embodiment, the water-based cationic material can have nitrate-based or sulfate anions, which can facilitate adsorption of the eluted dichroic material, particularly iodide ions.

[0037] For example, the water-based ionic material can include a compound of general formula 1:

[0038] [General formula 1] R 1 R 2 R 3 R 4 N + X (In the above general formula 1, X is a nitrate-based monovalent anion or a sulfate-based monovalent anion; R 1 , R 2 , R 3 and R 4 are each independently a substituted or unsubstituted, linear or branched alkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms.

[0039] In General Formula 1, the "number of carbon atoms" of the alkyl group refers only to the number of carbon atoms constituting the main chain of the linear or branched alkyl group. In General Formula 1, the "number of carbon atoms" of the aryl group refers only to the number of carbon atoms constituting the ring of the aryl group.

[0040] In the general formula 1, "substituted" in the context of "substituted" or "unsubstituted" means that one or more hydrogen atoms of the functional group are substituted with a linear or branched alkyl group having 1 to 10 carbon atoms, a hydroxyl group (OH), a linear or branched alkoxy group having 1 to 20 carbon atoms, or a substituted amide group. Here, the "substituted amide group" refers to a functional group represented by the following general formula 2.

[0041] [General formula 2] R 5 -C(=O)-NH-* (In the above general formula 2, * represents a linking site of elements, R 5 is a linear or branched alkyl group having 1 to 20 carbon atoms.

[0042] Preferably, in general formula 2, R 5 can be a straight or branched chain alkyl group having 10 to 20 carbon atoms.

[0043] Preferably, R 1 , R 2 , R 3 and R 4 At least one of R may be an alkyl group having 1 to 10 carbon atoms substituted with a hydroxyl group, or an aryl group having 6 to 20 carbon atoms substituted with a hydroxyl group. 1 , R 2 , R3 and R 4 At least one of the above may be an alkyl group having 1 to 5 carbon atoms substituted with a hydroxyl group. In this case, the ionic substance is well dissolved in the aqueous composition, which may be advantageous for adsorption of the eluted dichroic substance.

[0044] Preferably, R 1 , R 2 , R 3 and R 4 At least one of R may be an alkyl group having 1 to 10 carbon atoms substituted with an alkoxy group having 1 to 20 carbon atoms. More preferably, R 1 , R 2 , R 3 and R 4 One or more of the above may be an alkyl group having 1 to 5 carbon atoms substituted with an alkoxy group having 10 to 20 carbon atoms.

[0045] Preferably, R 1 , R 2 , R 3 and R 4 At least one of R may be an alkyl group having 1 to 10 carbon atoms substituted with the above-mentioned substituted amide group. 1 , R 2 , R 3 and R 4 One or more of the above may be an alkyl group having 1 to 5 carbon atoms substituted with a substituted amide group.

[0046] Preferably, X is NO3 - or R-SO4 - (wherein R can be a linear or branched alkyl group having 1 to 5 carbon atoms). More preferably, X is NO3 - or CH3SO4 - It could be.

[0047] Preferably, R 1 , R 2 , R 3 and R 4One or more of the above may be substituted with a straight-chain or branched-chain alkyl group having 10 to 20 carbon atoms or a straight-chain or branched-chain alkoxy group having 10 to 20 carbon atoms as the long-chain alkyl group or long-chain alkoxy group.

[0048] For example, the water-based ionic substance may include one or more of the following general formula 1-1 and general formula 1-2.

[0049] [ka] General formula 1-1

[0050] [ka] General formula 1-2

[0051] In one embodiment, the water-based ionic substance can be in a liquid phase or a solid phase, preferably in a liquid phase, at room temperature (for example, 20°C to 30°C).

[0052] The water-based ionic substance may be contained in an amount of 1 to 20 parts by weight, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 parts by weight, relative to 100 parts by weight of the total of the polyvinyl alcohol resin and the crosslinking agent. This range makes it easy to achieve the range of the water-based ionic substance content in the barrier layer.

[0053] When a polyvinyl alcohol-based resin is used as a vinyl-based polymer and a polyvinyl alcohol-based polarizer is included as a polarizer in a polarizing plate, the polarizing plate can have excellent adhesive strength.

[0054] Polyvinyl alcohol resins can include polyvinyl alcohol or its derivatives obtained by saponifying polyvinyl acetate, saponified copolymers of vinyl acetate and copolymerizable monomers, or modified polyvinyl alcohol resins obtained by acetylating, urethane-modifying, etherifying, grafting, or phosphate-modifying polyvinyl alcohol. These can be used alone or in combination. Examples of copolymerizable monomers include unsaturated carboxylic acids or their esters, such as maleic anhydride, fumaric acid, crotonic acid, itaconic acid, and (meth)acrylic acid; alpha-olefins, such as ethylene and propylene; (meth)allylsulfonic acid; monoalkyl maleates; sodium disulfonate alkyl maleates; N-methylolacrylamide; alkali acrylamidoalkylsulfonic acid salts; N-vinylpyrrolidone; and N-vinylpyrrolidone derivatives.

[0055] In one embodiment, the polyvinyl alcohol-based resin may include a polyvinyl alcohol-based resin containing an acetoacetyl group, which may help improve the adhesive strength of the adhesive layer.

[0056] In one embodiment, the degree of modification of the acetoacetyl group of the polyvinyl alcohol-based resin may be 1 mol% to 30 mol%, for example, 1 mol% to 10 mol%. By providing sufficient reaction sites with the crosslinking agent within this range, adhesive strength may be exhibited and the water resistance of the polarizing plate may also be improved. The method for producing the polyvinyl alcohol-based resin containing acetoacetyl groups is not particularly limited. For example, a method of dispersing the polyvinyl alcohol-based resin in acetic acid and adding diketene may be considered, but is not limited thereto.

[0057] The average polymerization degree and saponification degree of the polyvinyl alcohol resin are not particularly limited, but may be 100 to 3,000 and 85 to 100 mol %, respectively. Within these ranges, the adhesion between the polarizer and the barrier layer may be further improved.

[0058] The polyvinyl alcohol resin may be contained in an amount of 1 to 20 parts by weight, specifically 1 to 10 parts by weight, relative to 100 parts by weight of the aqueous solvent described below. Within this range, the viscosity of the barrier layer composition does not increase rapidly, providing excellent processability, facilitating the production of a thin barrier layer, and allowing the barrier layer to be formed with high adhesion to the polarizer.

[0059] The crosslinking agent can provide high adhesion of the barrier layer to the polarizer by crosslinking the polyvinyl alcohol-based resin.

[0060] The crosslinking agent may be contained in an amount of 0.01 to 10 parts by weight, specifically, for example, 0.01, 0.1, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 parts by weight, or 0.1 to 10 parts by weight, relative to 100 parts by weight of the polyvinyl alcohol-based resin. Within the above range, the adhesion of the barrier layer to the polarizer can be further improved.

[0061] The crosslinker may comprise one or more of an amine-containing crosslinker and a metal-containing crosslinker. Preferably, the crosslinker may comprise a mixture of an amine-containing crosslinker and a metal-containing crosslinker. In one embodiment, the crosslinker may comprise 50% by weight or more, for example, 50% to 100% by weight, of the amine-containing crosslinker. In one embodiment, the crosslinker may comprise 50% by weight or more, for example, 50% to 100% by weight, of the metal-containing crosslinker. In one embodiment, the crosslinker may comprise 95% by weight or more, for example, 99% to 100% by weight, of the mixture.

[0062] A crosslinking agent having an amine group can react with a polyvinyl alcohol-based resin to provide high adhesion between the barrier layer and the polarizer. Preferably, the crosslinking agent has one or more, preferably two or more, linear or branched primary amine groups (-NH2) or secondary amine groups (-NH-), which can provide high adhesive strength to the adhesive layer. Furthermore, the crosslinking agent was selected from among the multiple crosslinking agents used in polyvinyl alcohol-based water-based adhesives, taking into consideration the water-based ionic substances mentioned above.

[0063] In one embodiment, the crosslinker having amine groups can include one or more polyethyleneimine-based crosslinkers.

[0064] The polyethyleneimine crosslinking agent may include a linear or branched compound having primary and / or secondary amine groups and secondary and / or tertiary amine groups in the main chain. The primary and / or secondary amine groups can react with functional groups, specifically hydroxyl or acetoacetyl groups, of the polyvinyl alcohol resin to enhance adhesive strength.

[0065] As known to those skilled in the art, polyethyleneimine-based crosslinkers may include crosslinkers in which ethylene groups (-CH2CH2-) are linked via secondary amine groups and / or tertiary amine groups and have primary amine groups and / or secondary amine groups at their terminals.

[0066] The crosslinking agent having an amine group can be contained in an amount of 0.01 to 10 parts by weight, specifically 0.1 to 5 parts by weight, relative to 100 parts by weight of the polyvinyl alcohol-based resin. Within this range, the adhesion of the barrier layer to the polarizer can be further improved.

[0067] The metal-containing crosslinking agent may be a zirconium-containing compound. Examples of the zirconium-containing compound include zirconium halides such as zirconium oxychloride, zirconium hydroxychloride, zirconium tetrachloride, and zirconium bromide; zirconium salts of inorganic acids such as zirconium sulfate, basic zirconium sulfate, zirconium oxynitrate, zirconium oxyacetate, and zirconium oxycarbonate; zirconium formate, zirconium acetate, zirconium propionate, zirconium caprylate, zirconium stearate, zirconium lactate, zirconium nitrate, zirconium carbonate, and zirconium octylate. Examples of suitable zirconium compounds include zirconium salts of organic acids such as zirconium carbonate, zirconium citrate, and zirconium phosphate; zirconium complex salts such as ammonium zirconium carbonate, sodium zirconium sulfate, ammonium zirconium acetate, ammonium zirconium carbonate, potassium zirconium carbonate, sodium zirconium oxalate, sodium zirconium citrate, ammonium zirconium citrate, and ammonium zirconium lactate; and zirconium chelate complexes having one or more chelating agents as ligands. Among these, water-soluble zirconium-containing compounds are preferred, with zirconium oxyhalides, zirconium oxyacetate, zirconium sulfate, and zirconium oxynitrate being more preferred, and zirconium oxynitrate or its hydrate being most preferred.

[0068] The metal-containing crosslinking agent may be contained in an amount of 0.01 to 10 parts by weight, specifically 0.1 to 5 parts by weight, relative to 100 parts by weight of the polyvinyl alcohol-based resin. Within this range, the adhesion of the barrier layer to the polarizer can be further improved.

[0069] In the crosslinking agent, the weight ratio of the crosslinker having an amine group to the metal-containing crosslinker is 1:0.1 to 1:5, for example, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, 1:2.1, 1:2.2, 1:2 1:4.1, 1:4.2, 1:4.3, 1:4.4, 1:4.5, 1:4.6, 1:4.7, 1:4.8, 1:4.9, 1:5, 1:0.5~1:3. Within the above range, it may be easier to realize the effect of the barrier layer described above.

[0070] The aqueous solvent facilitates application of the barrier layer composition, allowing for the formation of a thin barrier layer. The aqueous solvent may be, but is not limited to, water, including ultrapure water. The aqueous solvent may be present as a residual amount in the barrier layer composition.

[0071] The aqueous composition for the barrier layer may further contain common additives other than the aqueous solvent, polyvinyl alcohol resin, crosslinking agent, and aqueous ionic substance, such as, but not limited to, one or more of UV absorbers, heat stabilizers, plasticizers, surfactants, reaction inhibitors, adhesion improvers, thixotropic agents, conductivity-imparting agents, antioxidants, leveling agents, stabilizers, and antistatic agents.

[0072] The barrier layer can be formed by applying an aqueous barrier layer composition to one surface of a polarizer to a predetermined thickness and then thermally curing the composition. For example, the thermal curing can be performed by one or more heat treatments at 40°C to 100°C for 1 minute to 60 minutes, without any particular limitation.

[0073] The barrier layer may have a thickness of 10 nm to 500 nm, for example, 50 nm to 200 nm. Within this range, the polarizing plate can be made thinner.

[0074] Polarizer The polarizer may include a conventional polarizer known to those skilled in the art. For example, the polarizer may include a polarizer made of a polyvinyl alcohol (PVA)-based resin film or a polypropylene (PP)-based resin film. Specifically, the polarizer may be a polyvinyl alcohol-based polarizer in which one or more dichroic materials, such as iodine and a dichroic dye, are adsorbed onto a polyvinyl alcohol-based resin film.

[0075] The polyvinyl alcohol-based resin film may have a saponification degree of 85 mol% to 100 mol%, specifically 98 mol% to 100 mol%. The polyvinyl alcohol-based resin film may have a polymerization degree of 1,000 to 10,000, specifically 1,500 to 10,000. A polarizer can be produced with a saponification degree and polymerization degree of 85 mol% to 100 mol%, specifically 98 mol% to 100 mol%. The polarizer can be produced by a conventional method known to those skilled in the art.

[0076] The polarizer may have a thickness of 5 μm to 30 μm, specifically 5 μm to 25 μm. When the thickness is in this range, it can be used in a polarizing plate, and the effect of making the polarizing plate thinner can be realized.

[0077] The polarizing plate may further include one or more protective layers.

[0078] protective layer A protective layer may be formed on at least one surface of the polarizer to protect the polarizer or to provide an additional function to the polarizing plate.

[0079] The protective layer may include one or more of an optically clear, protective film, and protective coating layer.

[0080] When the protective layer is a protective film type, it may include a protective film formed of an optically transparent resin. The protective film may be formed by melting and extruding the resin. If necessary, a stretching process may be added. The resin may include one or more of cellulose ester-based resins including triacetyl cellulose, cyclic polyolefin-based resins including cyclic olefin polymers (COP), polycarbonate-based resins, polyester-based resins including polyethylene terephthalate (PET), polyethersulfone-based resins, polysulfone-based resins, polyamide-based resins, polyimide-based resins, acyclic polyolefin-based resins, polyacrylate-based resins including polymethyl methacrylate resin, polyvinyl alcohol-based resins, polyvinyl chloride-based resins, and polyvinylidene chloride-based resins. Preferably, the protective film may be a film formed of a cyclic polyolefin-based resin including cyclic polyolefin.

[0081] When the protective layer is a protective coating layer type, it can improve adhesion to the polarizer, transparency, mechanical strength, thermal stability, moisture blocking property, and durability. In one specific example, the protective coating layer for the protective layer can be formed from an active energy ray-curable resin composition containing an active energy ray-curable compound and a polymerization initiator.

[0082] The active energy ray-curable compound may include one or more of a cationically polymerizable curable compound, a radically polymerizable curable compound, a urethane resin, and a silicone resin. The cationically polymerizable curable compound may be an epoxy-based compound having at least one epoxy group in the molecule, or an oxetane-based compound having at least one oxetane ring in the molecule. The radically polymerizable curable compound may be a (meth)acrylic-based compound having at least one (meth)acryloyloxy group in the molecule.

[0083] In addition to the optically transparent resin or the active energy ray-curable compound, the protective layer may further contain additives known to those skilled in the art, such as antioxidants, UV absorbers, ionic conductive agents, conductivity-imparting additives such as conductive metal oxide fine particles, light-diffusing additives, and viscosity modifiers.

[0084] The thickness of the protective layer can be 5 μm to 200 μm, specifically 20 μm to 120 μm, 50 μm to 100 μm in the case of a protective film type, and 5 μm to 50 μm in the case of a protective coating layer type. Within the above range, the protective layer can be used in optical display devices.

[0085] The protective layer may include a functional coating layer formed on at least one surface thereof, or may be surface-treated. The functional coating layer may be, but is not limited to, a hard coating layer, an anti-fingerprint layer, an anti-reflection layer, a low-reflection layer, an ultra-low-reflection layer, an anti-glare layer, etc. The surface treatment may be, but is not limited to, a corona treatment, etc.

[0086] The protective layer can be attached to a polarizer or an adherend other than a polarizer via an adhesive layer. The adhesive layer can be formed of, but is not limited to, a water-based adhesive or a photo-curable adhesive. The water-based adhesive and the photo-curable adhesive can be appropriately used by referring to the details known to those skilled in the art.

[0087] When the protective layer is laminated on the polarizer opposite the first adhesive layer, the protective layer may be referred to as an upper protective layer. In this case, the upper protective layer may include a UV absorber. The UV absorber can prevent external light from damaging optical elements, such as light-emitting elements, in the optical display panel.

[0088] The polarizing plate may further include one or more retardation layers. The polarizing plate may include one or more retardation layers, or two or more retardation layers.

[0089] retardation layer The retardation layer can improve the quality of the screen by circularly polarizing the linearly polarized light emitted after the external light passes through the polarizer, thereby preventing reflection of the external light.

[0090] In one embodiment, the retardation layer may have an in-plane retardation (Re) at a wavelength of 550 nm of 225 nm to 350 nm, specifically 225 nm to 300 nm, for example, a λ / 2 retardation. Within this range, the reflectance to external light can be reduced, thereby improving the quality of the screen.

[0091] In another embodiment, the retardation layer may have an in-plane retardation (Re) at a wavelength of 550 nm of 100 nm to 220 nm, specifically 100 nm to 180 nm, for example, a λ / 4 retardation. Within this range, the reflectance to external light can be reduced, thereby improving the quality of the screen.

[0092] In yet another embodiment, the retardation layer may be a laminate of a first retardation layer having an in-plane retardation (Re) of 225 nm to 350 nm, specifically 225 nm to 300 nm, for example, a λ / 2 retardation at a wavelength of 550 nm, and a second retardation layer having an in-plane retardation (Re) of 100 nm to 220 nm, specifically 100 nm to 180 nm, for example, a λ / 4 retardation at a wavelength of 550 nm.

[0093] In this specification, the "in-plane retardation (Re)" can be calculated by Re = (nx - ny) × d (nx and ny are the refractive indices in the slow axis direction and fast axis direction of the retardation layer, respectively, and d is the thickness of the retardation layer (unit: nm)).

[0094] The retardation layer may have a thickness of 0.01 μm to 30 μm, for example, 1 μm to 10 μm. Within this range, the polarizing plate can be made thinner and a desired retardation can be achieved.

[0095] The retardation layer may be a film or a coating layer, and preferably a coating layer to achieve a thin polarizing plate.

[0096] The retardation layer can be a liquid crystal layer or a non-liquid crystal layer.

[0097] The film-type retardation layer may be manufactured from a resin commonly known to those skilled in the art, and may include, for example, one or more of cellulose ester-based resins such as triacetyl cellulose (TAC), cyclic polyolefin (COP)-based resins such as amorphous cyclic polyolefin, polycarbonate-based resins, polyester-based resins such as polyethylene terephthalate (PET), polyethersulfone-based resins, polysulfone-based resins, polyamide-based resins, polyimide-based resins, acyclic polyolefin-based resins, polyacrylate-based resins such as polymethyl methacrylate resin, polyvinyl alcohol-based resins, polyvinyl chloride-based resins, and polyvinylidene chloride-based resins.

[0098] The retardation layer in the form of a coating layer may include a coating layer formed of a non-liquid crystal thermosetting or active energy ray curable composition, or a coating layer formed of a liquid crystal composition.

[0099] The polarizing plate may include one or more adhesive layers. The adhesive layer may be included in one or more layers of the polarizing plate, or in two or more layers.

[0100] adhesive layer The adhesive layer can adhere the barrier layer to the retardation layer or the barrier layer to the protective layer.

[0101] In one embodiment, the adhesive layer may be a pressure sensitive adhesive (PSA). For example, the pressure sensitive adhesive may include a cured product of a composition including an adhesive resin and a curing agent.

[0102] 1 is a cross-sectional view of a polarizing plate according to one embodiment. Referring to FIG. 1, the polarizing plate may include a polarizer 100, a protective layer 200 laminated on an upper surface of the polarizer 100, and a barrier layer 300 laminated on a lower surface of the polarizer 100.

[0103] 2 is a cross-sectional view of a polarizing plate according to another embodiment. Referring to FIG. 2, the polarizing plate may include a polarizer 100, a protective layer 200 laminated on an upper surface of the polarizer 100, a barrier layer 300, an adhesive layer 400, and a retardation layer 500 laminated in this order on a lower surface of the polarizer 100.

[0104] 1 and 2, the protective layer 200 can be adhered to the polarizer 100 by an adhesive layer. The adhesive layer can be formed of a water-based adhesive or a photocurable adhesive.

[0105] The optical display device of the present invention includes the polarizing plate of the present invention.

[0106] For example, the optical display device may include, but is not limited to, a light emitting display device, including an organic light emitting display device, etc. For example, the optical display device may include a flexible optical display device.

[0107] The present invention will be described in more detail with reference to the following examples, which are provided for illustrative purposes only and are not intended to limit the scope of the present invention. [Example]

[0108] <Manufacture of polarizer> A polyvinyl alcohol film (PS#60, Kuraray Co., Ltd., degree of polymerization: 2800, thickness: 60 μm) was immersed in an aqueous solution with 0.3% iodine concentration at 55°C for dyeing. The film was uniaxially stretched in the MD direction in the aqueous solution at a stretch ratio of 6.0. The stretched polyvinyl alcohol film was immersed in an aqueous solution of 3 wt% boric acid and 2 wt% potassium iodide for color correction. The film was dried at 50°C for 4 minutes to produce a polarizer (thickness: 25 μm, light transmittance: 45%).

[0109] <Production of aqueous composition for barrier layer> The polyvinyl alcohol resin was added to 100 parts by weight of water at 95°C and dissolved with stirring for 60 minutes. After the resulting solution was completely cooled to room temperature, the zirconium-containing curing agent and the amine-based curing agent were mixed to prepare a mixture of the polyvinyl alcohol resin, the zirconium chelate-containing curing agent, and the amine-based curing agent.

[0110] The polyvinyl alcohol resin used was Z200 manufactured by Mitsubishi Chemical Corporation.

[0111] The zirconium-containing hardener used was Zircosol Zn (ZrO(NO3)2) manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.

[0112] The amine-based curing agent used was Nippon Shokubai Co., Ltd.'s SP018 (polyethyleneimine-based crosslinking agent).

[0113] The mixture of polyvinyl alcohol resin, zirconium-containing curing agent and amine-based curing agent contains, on a solids basis, 100 parts by weight of polyvinyl alcohol resin, 5 parts by weight of zirconium-containing curing agent and 5 parts by weight of amine-based curing agent.

[0114] An aqueous composition for a barrier layer was prepared by adding 20 parts by weight of N,N-bis(2-hydroxyethyl)-N-(3'-dodecyloxy-2'-hydroxypropyl)methylammonium methyl sulfate of the following general formula 1-1 to 100 parts by weight of a mixture of a polyvinyl alcohol resin, a zirconium chelate-containing curing agent, and an amine-based curing agent.

[0115] [ka] General formula 1-1

[0116] Table 1 below shows the content of the compound of general formula 1-1 in terms of solid content relative to 100 parts by weight of a mixture containing 100 parts by weight of polyvinyl alcohol resin, 5 parts by weight of zirconium-containing curing agent, and 5 parts by weight of amine-based curing agent.

[0117] In Table 1 below, "-" indicates that the corresponding ingredient is not included.

[0118] <Production of polarizing plates> Three parts by weight of polyvinyl alcohol resin (Mitsubishi Chemical Corporation, Z200, acetoacetyl-modified polyvinyl alcohol, average polymerization degree: 1200, saponification degree: 99 mol%, acetoacetyl-modification degree: 5 mol%) was added to 100 parts by weight of water at 95°C and dissolved with stirring for 60 minutes. After the resulting solution was completely cooled to room temperature, an amine-based crosslinker (Nippon Shokubai Co., Ltd., SP018, solids content 40 wt%, polyethyleneimine-based crosslinker) was added to prepare an adhesive. The polyethyleneimine-based crosslinker was included at 1 part by weight per 100 parts by weight of polyvinyl alcohol resin, based on solids content.

[0119] The adhesive prepared above was applied to the upper surface of the polarizer to a predetermined thickness, and then the lower surface of a COP film (Zeon Corporation, with a hard coating layer formed on the upper surface, thickness: 28 μm) was attached thereto. The film was then treated in a drying oven at 50°C for 1 minute and then in a drying oven at 85°C for 3 minutes to bond the COP film to the upper surface of the polarizer.

[0120] The aqueous composition for the barrier layer prepared above was applied to the lower surface of the polarizer prepared above to a predetermined thickness, and a non-saponified triacetyl cellulose film (Normal TAC, thickness: 40 μm) was attached thereto.

[0121] Thereafter, the film was dried at 80°C for 3 minutes, and the unsaponified triacetyl cellulose film was removed to produce a polarizing plate laminated in the following order: COP film (thickness: 28 μm), adhesive layer (thickness: 3 μm), polarizer (thickness: 25 μm), and barrier layer (thickness: 100 nm).

[0122] Examples 2 to 5 and Comparative Example 1 A polarizing plate was manufactured in the same manner as in Example 1, except that the amount of N,N-bis(2-hydroxyethyl)-N-(3'-dodecyloxy-2'-hydroxypropyl)methylammonium methyl sulfate of general formula 1-1 was changed relative to 100 parts by weight of the mixture of polyvinyl alcohol resin, zirconium chelate curing agent, and amine curing agent in the aqueous adhesive composition for polarizing plate as shown in Table 1 below.

[0123] Example 6 A polarizing plate was prepared in the same manner as in Example 1, except that 20 parts by weight of stearamidopropyldimethyl-2-hydroxyethylammonium nitrate, a compound of the following general formula 1-2, was used instead of the compound of general formula 1 in Example 1.

[0124] [ka] General formula 1-2

[0125] Examples 7 to 10 and Comparative Example 2 A polarizing plate was manufactured in the same manner as in Example 6, except that the amount of stearamidopropyldimethyl-2-hydroxyethylammonium nitrate of general formula 1-2 added relative to 100 parts by weight of the mixture of polyvinyl alcohol resin, zirconium chelate curing agent, and amine curing agent in the aqueous adhesive composition for polarizing plate was changed as shown in Table 1 below.

[0126] Comparative Example 3 A polarizing plate was produced in the same manner as in Example 1, except that the compound of formula 1-1 was not used.

[0127] The polarizing plates produced in the examples and comparative examples have the structures shown in Table 1 below, and the physical properties shown in Table 1 below were evaluated.

[0128] A vacuum adhesive layer (acrylic PSA) was attached to the bottom surface of the polarizing plate, which was then attached to a glass plate using the vacuum adhesive layer to prepare a test specimen. The test specimen was then left in a high-temperature, high-humidity chamber at constant temperature and humidity conditions of 60°C and 95% relative humidity for 500 hours. The presence or absence of purple color change in the barrier layer, vacuum adhesive layer, and glass plate due to iodine elution from the polarizer was evaluated. A perfect ⊚ was used if there was no color change; a perfect ◯ was used if there was a slight color change in some areas but the specimen was still usable; a perfect △ was used if there was a color change that was difficult to use but not entirely; and an X was used if there was a color change over the entire surface.

[0129] [Table 1]

[0130] In Table 1 above, "mixture" refers to a mixture of a polyvinyl alcohol resin, a zirconium-containing crosslinking agent, and an amine-based crosslinking agent.

[0131] As shown in Table 1 above, the polarizing plate of the present invention does not have a protective layer on at least one side of the polarizer, and it was confirmed that there was no color change at all after being left at high temperature and high humidity for a long period of time, by preventing the elution of the dichroic substance from the polarizer.

[0132] On the other hand, Comparative Example 3, which did not contain any water-based ionic material, showed color change across the entire surface and was unable to achieve the effects of the polarizing plate of the Examples.Comparative Examples 1 and 2, which contained water-based ionic material but in an amount exceeding 18 wt%, showed even more color change than the Examples.

[0133] Simple modifications or alterations of the present invention can be easily implemented by a person having ordinary skill in the art, and all such modifications and alterations can be considered to be included within the scope of the present invention.

Claims

1. a polarizer and a barrier layer laminated on one surface of the polarizer, the barrier layer comprises a cured product of a composition comprising a polyvinyl alcohol-based resin, a crosslinking agent, and a water-based ionic substance; The polarizing plate, wherein the water-based ionic substance is contained in the barrier layer in an amount of 0.5% by weight to 18% by weight.

2. 2. The polarizing plate according to claim 1, wherein the water-based ionic substance is contained in an amount of 1 to 20 parts by weight with respect to a total of 100 parts by weight of the polyvinyl alcohol-based resin and the crosslinking agent.

3. 2. The polarizing plate according to claim 1, wherein the water-based ionic substance is in a liquid phase at 20°C to 30°C.

4. 2. The polarizing plate according to claim 1, wherein the water-based ionic substance comprises an ammonium-based cation and an anion.

5. 5. The polarizing plate according to claim 4, wherein the ammonium-based cation has an aliphatic or aromatic hydrocarbon group having a hydroxyl group or being substituted with a hydroxyl group.

6. 5. The polarizing plate according to claim 4, wherein the anion is a nitrate-based anion or a sulfate anion.

7. The polarizing plate according to claim 1 , wherein the water-based ionic material comprises a compound represented by the following general formula 1: [General formula 1] R １ R ２ R ３ R ４ N ＋ X (In the general formula 1, X is a nitrate-based monovalent anion or a sulfate-based monovalent anion; R １ , R ２ , R ３ and R ４ are each independently a substituted or unsubstituted, linear or branched alkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms.

8. In the general formula 1, R １ , R ２ , R ３ and R ４ 8. The polarizing plate according to claim 7, wherein at least one of the above is an alkyl group having 1 to 10 carbon atoms and substituted with a hydroxyl group, or an aryl group having 6 to 20 carbon atoms and substituted with a hydroxyl group.

9. In the general formula 1, the R １ , R ２ , R ３ and R ４ 8. The polarizing plate according to claim 7, wherein one or more of the following are substituted with a linear or branched alkyl group having 10 to 20 carbon atoms, or a linear or branched alkoxy group having 10 to 20 carbon atoms.

10. 2. The polarizing plate according to claim 1, wherein the water-based ionic substance comprises at least one of the following general formulas 1-1 and 1-2: 【Chemical 1】 General formula 1-1 【Chemistry 2】 General formula 1-2

11. The polarizing plate according to claim 1 , wherein the crosslinking agent comprises at least one of an amine group-containing crosslinking agent and a metal-containing crosslinking agent.

12. The composition comprises:

2. The polarizing plate according to claim 1, comprising: 100 parts by weight of the polyvinyl alcohol-based resin; 0.01 to 10 parts by weight of the crosslinking agent per 100 parts by weight of the polyvinyl alcohol-based resin; and 1 to 20 parts by weight of the water-based ionic substance per 100 parts by weight of the polyvinyl alcohol-based resin and the crosslinking agent combined.

13. The polarizing plate according to claim 1 , wherein the composition is a water-based composition.

14. The polarizing plate according to claim 1 , wherein the barrier layer is formed directly on the polarizer.

15. The polarizing plate according to claim 1 , further comprising at least one of a protective layer, a retardation layer, and an adhesive layer.

16. An optical display device comprising the polarizer according to any one of claims 1 to 15.

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