Polarizing plate and image display device including the same

Abstract

To provide a polarizing plate which can improve the occurrence of leak light by controlling the deflection characteristics of a large-sized panel without a reverse curling phenomenon.SOLUTION: A polarizing plate comprises: a polarizer 110; and a surface treatment film 120 laminated on one surface of the polarizing plate 110. The surface treatment film includes a (meth)acrylic film as a base film 121 and satisfies 70≤a×b / c≤300. Here, a is the thickness (μm) of the base film, b is the tensile strength (Mpa) of the polarizing plate and c is the moisture vapor permeability (g / m2 / 24hr) of the surface treatment film. There is also provided an image display device having the polarizing plate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polarizing plate and an image display device including the same, and more particularly to a polarizing plate and an image display device including the same that can control the bending characteristics of a large panel without causing reverse curling and reduce the occurrence of light leakage. [Background technology]

[0002] Liquid crystal display devices (LCDs) are used in a variety of applications, including laptops, mobile phones, and LCD TVs. LCDs generally consist of a liquid crystal cell containing liquid crystal, a polarizing plate, and an adhesive layer to bond them together.

[0003] Furthermore, polarizing plates used in liquid crystal display devices generally include a polarizer (also called a "polarizing film") in which an iodine-based compound or a dichroic dye is adsorbed and aligned in a polyvinyl alcohol (PVA) resin film aligned in a specific direction. The polarizing plate has a multilayer structure in which a polarizer protective film, typically a triacetyl cellulose (TAC) film, is laminated on at least one surface of the polarizer via an adhesive.

[0004] Korean Patent Publication No. 10-2013-0137161 discloses a polarizing plate including an optical laminate having a hard coat layer on one surface of a triacetyl cellulose substrate and a polarizing element.

[0005] However, when the polarizing plate is applied to a large panel, the panel bends significantly, resulting in light leakage.

[0006] Therefore, there is a demand for the development of a polarizing plate that can control the bending characteristics of a large panel and reduce the occurrence of light leakage.

[0007] Furthermore, there is a need to develop a method for suppressing reverse curling of polarizing plates so as to prevent the generation of bubbles during panel lamination. Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a polarizing plate capable of controlling the bending characteristics of a large panel without causing reverse curling, thereby reducing the occurrence of light leakage.

[0009] Another object of the present invention is to provide an image display device including the polarizing plate. [Means for solving the problem]

[0010] On the other hand, the present invention provides a polarizing plate including a polarizer and a surface-treated film laminated on one surface of the polarizer, The surface-treated film contains a (meth)acrylic film as a base film, A polarizing plate that satisfies the following mathematical formula 1 is provided. [Mathematical formula 1] 70≦a×b / c≦300 In the above formula, a is the thickness of the substrate film (μm), b is the tensile strength of the polarizer (Mpa), c is the moisture permeability of the surface-treated film (g / m2 / 24hr).

[0011] In one embodiment of the present invention, the surface-treated film may include a substrate film having a surface-treated layer formed on at least one surface thereof.

[0012] In one embodiment of the present invention, the thickness of the substrate film may be 60 μm or more.

[0013] The polarizing plate according to one embodiment of the present invention may have a tensile strength of 90 MPa to 150 MPa.

[0014] In one embodiment of the present invention, the moisture permeability of the surface-treated film may be 70 g / m2 / 24 hr or less.

[0015] In one embodiment of the present invention, the polarizer may have a thickness of 5 μm to 30 μm.

[0016] In one embodiment of the present invention, the surface treatment layer may be a hard coating layer or an anti-glare coating layer.

[0017] The polarizing plate according to one embodiment of the present invention may further include a retardation layer laminated on the other surface of the polarizer.

[0018] In one embodiment of the present invention, the retardation layer may have an in-plane retardation (R0) of 0 to 10 nm at a wavelength of 550 nm.

[0019] In the polarizing plate according to one embodiment of the present invention, a pressure-sensitive adhesive layer may be further laminated on the surface of the retardation layer opposite to the surface facing the polarizer.

[0020] In the polarizing plate according to one embodiment of the present invention, a peelable protective film may be further laminated on the surface of the surface-treated film opposite to the surface facing the polarizer.

[0021] In the polarizing plate according to one embodiment of the present invention, a release film may be further laminated on the surface of the pressure-sensitive adhesive layer opposite to the surface facing the retardation layer.

[0022] On the other hand, the present invention provides an image display device including the polarizing plate. [Effects of the Invention]

[0023] The polarizing plate according to the present invention includes a (meth)acrylic film as the substrate film of the surface-treated film, and satisfies a specific mathematical formula, thereby controlling the bending characteristics even when applied to a large panel without causing reverse curling, thereby reducing the occurrence of light leakage. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a schematic cross-sectional view of a polarizing plate according to one embodiment of the present invention. [Figure 2] 1 is a schematic cross-sectional view of a polarizing plate according to one embodiment of the present invention. [Figure 3] 1 is a schematic cross-sectional view of a polarizing plate according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention will now be described in more detail.

[0026] The present invention provides a polarizing plate including a polarizer and a surface-treated film laminated on one surface of the polarizer, The surface-treated film contains a (meth)acrylic film as a base film, The polarizing plate satisfies the following mathematical formula 1. [Mathematical formula 1] 70≦a×b / c≦300 In the above formula, a is the thickness of the substrate film (μm), b is the tensile strength of the polarizer (Mpa), c is the moisture permeability of the surface-treated film (g / m2 / 24hr).

[0027] FIG. 1 is a cross-sectional view showing the structure of a polarizing plate according to one embodiment of the present invention.

[0028] Referring to FIG. 1, a polarizing plate according to one embodiment of the present invention includes a polarizer 110 and a surface treatment film 120 laminated on one surface of the polarizer.

[0029] The surface-treated film 120 may include a base film 121 having a surface-treated layer 122 formed on at least one surface thereof.

[0030] The polarizing plate according to one embodiment of the present invention includes a (meth)acrylic film as the substrate film of the surface-treated film, and satisfies Equation 1, thereby controlling the bending characteristics of a large panel without reverse curling and reducing light leakage. Therefore, the polarizing plate according to one embodiment of the present invention can be advantageously applied to LCDs for large TVs, in particular.

[0031] As described above, the polarizing plate according to one embodiment of the present invention satisfies the following mathematical formula 1. [Mathematical formula 1] 70≦a×b / c≦300 In the above formula, a is the thickness of the substrate film (μm), b is the tensile strength of the polarizer (Mpa), c is the moisture permeability of the surface-treated film (g / m2 / 24hr).

[0032] In the polarizing plate according to one embodiment of the present invention, if the a×b / c value is less than 70, the amount of bending may increase when applied to a panel, resulting in light leakage. If the a×b / c value exceeds 300, the polarizing plate may reverse curl, resulting in air bubbles when attached to a panel.

[0033] The surface-treated film uses a (meth)acrylic film as a substrate film.

[0034] The thickness of the substrate film may be 60 μm or more, preferably 60 μm to 100 μm. If the thickness of the substrate film is less than 60 μm, it may be difficult to control the bending characteristics of a large panel, and if it exceeds 100 μm, problems may occur such as reverse curling of the polarizing plate, reduced transparency, or increased weight of the polarizing plate.

[0035] The polarizing plate according to one embodiment of the present invention may have a tensile strength of 85 MPa to 150 MPa.

[0036] The tensile strength is a force that indicates the strength of a material, and is the value obtained by dividing the maximum tensile load until the material breaks by the cross-sectional area of ​​the material. The tensile strength is obtained by measuring a polarizing plate using the method described in the experimental examples below.

[0037] In one embodiment of the present invention, if the tensile strength of the polarizing plate is less than 85 MPa, the amount of deflection may increase due to an increase in the contraction and expansion rate of the polarizing plate, and if it exceeds 150 MPa, the tensile strength may be so high that the balance with the lower plate may be disrupted, resulting in an increase in the amount of deflection.

[0038] In one embodiment of the present invention, the moisture permeability of the surface-treated film may be 70 g / m2 / 24 hr or less.

[0039] The moisture permeability of the surface-treated film is a value measured by a method using a moisture permeability cup according to the method described in the experimental examples below.

[0040] If the moisture permeability of the surface-treated film exceeds 70 g / m 2 / 24 hr, it may become difficult to control the bending characteristics of a large panel.

[0041] Each component of the polarizing plate 100 will be described in detail below.

[0042] In one embodiment of the present invention, the polarizer 110 is an optical film that serves to convert incident natural light into a desired single polarization state (linear polarization state), and is not particularly limited as long as it can perform a polarization function generally known in the art.

[0043] For example, the polarizer 110 specifically includes a film manufactured by adsorbing a dichroic substance such as iodine or a dichroic dye onto a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or a partially saponified ethylene-vinyl acetate copolymer film, followed by uniaxial stretching the film; and a polyene-based oriented film such as a dehydrated polyvinyl alcohol film or a dechlorinated polyvinyl chloride film. Among these, a polarizer manufactured by adsorbing a dichroic substance such as iodine onto a polyvinyl alcohol film and then uniaxially stretching the film is particularly preferred from the viewpoint of high polarization dichroism.

[0044] The thickness of the polarizer 110 is in the range of 5 μm to 30 μm, preferably 15 to 25 μm. If the thickness of the polarizer 110 is less than 5 μm, it becomes difficult to control the manufacturing process of the polarizing plate, and the polarizer may break or the axial uniformity of the polarizer may decrease. If the thickness of the polarizer is more than 30 μm, the shrinkage rate of the polarizer may increase after being left in a heat-resistant or moist heat-resistant state, and the amount of deflection may increase.

[0045] A polarizer produced by adsorbing iodine onto a polyvinyl alcohol-based film and then uniaxially stretching the film may be produced, for example, by immersing the polyvinyl alcohol-based film in an iodine aqueous solution for coloring and stretching the film to 3 to 7 times its original length. The aqueous solution may contain boric acid, zinc sulfate, zinc chloride, or the like, or the polyvinyl alcohol-based film may be immersed in an aqueous solution of potassium iodide, etc., as needed. Furthermore, the polyvinyl alcohol-based film may be immersed in water and washed before coloring, as needed. Washing the polyvinyl alcohol-based film not only removes dirt and antiblocking agents from the film surface, but also swells the polyvinyl alcohol-based film, preventing unevenness such as uneven coloring. The film may be stretched after, during, or before coloring the film with iodine. Stretching may be performed using an aqueous solution of boric acid or potassium iodide, or using an aqueous solution.

[0046] Examples of commercially available polarizers include VF-PS7500, VF-PE6000, VF-PE5000, VF-PE4500, VF-PE3000, VF-PE2000 (Kuraray), and M-7500 (Nippon Gosei).

[0047] As the base film 121 of the surface-treated film 120, a (meth)acrylic film is used as described above.

[0048] Examples of the (meth)acrylic film include polymethyl (meth)acrylate and polyethyl (meth)acrylate, and polymethyl methacrylate is particularly preferred from the viewpoint of controlling the amount of deflection.

[0049] In one embodiment of the present invention, the surface treatment layer 122 may be formed by applying and curing a suitable surface treatment coating composition on the substrate film 121. The surface treatment layer 122 may be a hard coating layer or an anti-glare coating layer.

[0050] For example, the surface-treating coating composition may be a composition for forming an antiglare layer or a hard coating composition, and may include a light-transmitting resin, light-transmitting particles, a photopolymerization initiator, and a solvent.

[0051] The light-transmitting resin is a photocurable resin, and the photocurable resin may contain a photocurable (meth)acrylate oligomer and / or monomer. As the photocurable (meth)acrylate oligomer, epoxy (meth)acrylate, urethane (meth)acrylate, etc. are commonly used, with urethane (meth)acrylate being preferred. The monomer may be used without any particular limitation as long as it is a commonly used one. Preferred are monomers having an unsaturated group such as a (meth)acryloyl group, vinyl group, styryl group, or allyl group as a photocurable functional group in the molecule, and among these, monomers having a (meth)acryloyl group are preferred.

[0052] The light-transmitting particles may be any particles used in the art that can provide surface treatment properties, and are not particularly limited. Examples of light-transmitting particles that may be used include silica particles, silicone resin particles, melamine-based resin particles, acrylic-based resin particles, styrene-based resin particles, acrylic-styrene-based resin particles, polycarbonate-based resin particles, polyethylene-based resin particles, and vinyl chloride-based resin particles. The light-transmitting particles exemplified above may be used alone or in combination of two or more. The average particle size of the light-transmitting particles is preferably 1 to 10 μm. If the average particle size of the light-transmitting particles is less than 1 μm, it is difficult to form irregularities on the surface of the surface treatment layer 122, resulting in reduced surface treatment properties. If the average particle size of the light-transmitting particles is more than 10 μm, the surface of the surface treatment layer 122 becomes rough, resulting in reduced visibility.

[0053] The photopolymerization initiator may be any one used in the art without any particular limitation. Specifically, the photopolymerization initiator may be at least one selected from the group consisting of 2-methyl-1-[4-(methylthio)phenyl]2-morpholinepropanone-1, diphenylketone benzyl dimethyl ketal, 2-hydroxy-2-methyl-1-phenyl-1-one, 4-hydroxycyclophenyl ketone, dimethoxy-2-phenylacetophenone, anthraquinone, fluorene, triphenylamine, carbazole, 3-methylacetophenone, 4-chloroacetophenone, 4,4-dimethoxyacetophenone, 4,4-diaminobenzophenone, 1-hydroxycyclohexyl phenyl ketone, and benzophenone.

[0054] The solvent may be any solvent known in the art, without particular limitation. For example, preferred solvents include alcohols (methanol, ethanol, isopropanol, butanol, methyl cellosolve, ethyl cellosolve, 1-methoxy-2-propanol, propylene glycol monomethyl ether, etc.), ketones (methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, cyclohexanone, etc.), hexanes (hexane, heptane, octane, etc.), and benzenes (benzene, toluene, xylene, etc.). The solvents listed above may be used alone or in combination of two or more.

[0055] In addition to the above components, the surface treatment coating composition may further contain components commonly used in the technical field, such as antioxidants, UV absorbers, light stabilizers, thermal polymerization inhibitors, leveling agents, surfactants, lubricants, and antifouling agents.

[0056] The surface treatment layer 122 can be formed by applying a surface treatment coating composition to one surface of the substrate film 121, drying it, and then curing it with UV light.

[0057] The surface treatment coating composition can be applied to a substrate film (coating process) using any known method such as a die coater, air knife, reverse roll, spray, blade, casting, gravure, microgravure, or spin coating.

[0058] After application, the surface-treating coating composition is dried by evaporating volatiles at a temperature of 30 to 150°C for 10 seconds to 1 hour, more specifically, for 30 seconds to 30 minutes, and then cured by irradiation with UV light. The UV light irradiation dose may be approximately 0.01 to 10 J / cm2, more specifically, 0.1 to 2 J / cm2. The thickness of the surface-treated layer formed in this case may be approximately 1 to 30 μm, more specifically, 1.5 to 10 μm.

[0059] The polarizer 110 may be attached to a surface treatment film 120 on one surface thereof via an adhesive layer (not shown).

[0060] The adhesive layer may be formed from a water-based adhesive in which an adhesive component is dissolved or dispersed in water, a composition that hardens when irradiated with active energy rays (hereinafter, sometimes referred to as an active energy ray-curable adhesive), or the like.

[0061] Examples of aqueous adhesives include compositions containing a polyvinyl alcohol resin or a urethane resin as a main component, and containing a crosslinking agent or a curing compound such as an isocyanate compound or an epoxy compound to improve adhesiveness.

[0062] When the main component of the adhesive is a polyvinyl alcohol resin, examples of the polyvinyl alcohol resin include modified polyvinyl alcohol resins such as partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, and amino group-modified polyvinyl alcohol. The adhesive is an aqueous solution of the polyvinyl alcohol resin, and the concentration of the polyvinyl alcohol resin in the adhesive is usually 1 to 10 parts by weight, and preferably 1 to 5 parts by weight, per 100 parts by weight of water.

[0063] The adhesive containing the aqueous solution of polyvinyl alcohol-based resin may contain a curable compound such as a polyaldehyde, a water-soluble epoxy resin, a melamine-based compound, a zirconia-based compound, or a zinc compound in order to improve adhesiveness.

[0064] Examples of water-soluble epoxy resins include polyamide epoxy resins obtained by reacting epichlorohydrin with polyamide polyamines obtained by reacting polyalkylene polyamines such as diethylenetriamine or triethylenetetramine with dicarboxylic acids such as adipic acid. Commercially available polyamide epoxy resins include "Sumirez Resin (registered trademark) 650" and "Sumirez Resin 675" (both manufactured by Sumika Chemtex Co., Ltd.) and "WS-525" (manufactured by Nippon PMC Corporation). The content of the water-soluble epoxy resin is typically 1 to 100 parts by weight, preferably 1 to 50 parts by weight, per 100 parts by mass of the polyvinyl alcohol-based resin.

[0065] When the main component of the adhesive is a urethane resin, the urethane resin is preferably a polyester ionomer urethane resin. A polyester ionomer urethane resin is a urethane resin having a polyester skeleton, into which an ionic component (hydrophilic component) has been introduced. The ionomer urethane resin is emulsified in water to form an emulsion without using an emulsifier. A water-based adhesive containing a polyester ionomer urethane resin preferably contains a water-soluble epoxy compound as a crosslinking agent.

[0066] When the polarizer 110 and the surface-treated film 120 are bonded together using a water-based adhesive, the water-based adhesive is injected between the polarizer 110 and the surface-treated film 120, and then the adhesive is dried to evaporate the water while allowing a thermal crosslinking reaction to proceed, thereby imparting sufficient adhesiveness to both the polarizer 110 and the surface-treated film 120.

[0067] Active energy ray-curable adhesives are cured by irradiation with active energy rays. Examples of active energy ray-curable adhesives include cationically polymerizable active energy ray-curable adhesives containing an epoxy compound and a cationic polymerization initiator, radically polymerizable active energy ray-curable adhesives containing an acrylic curing component and a radical polymerization initiator, active energy ray-curable adhesives containing both a cationically polymerizable curing component such as an epoxy compound and a radically polymerizable curing component such as an acrylic compound, and further containing a cationic polymerization initiator and a radical polymerization initiator, and electron beam-curable active energy ray-curable adhesives that are cured by irradiation with an electron beam. Electron beam-curable active energy ray-curable adhesives do not contain an initiator.

[0068] Among these, a cationically polymerizable active energy ray-curable adhesive containing an epoxy compound and a cationic polymerization initiator is preferred. The active energy ray-curable adhesive preferably does not substantially contain a solvent.

[0069] The cationic polymerizable epoxy compound is selected from those that are liquid at room temperature, have appropriate fluidity even in the absence of a solvent, and provide appropriate cured adhesive strength. Furthermore, an active energy ray-curable adhesive obtained by selecting a cationic polymerization initiator suitable for the epoxy compound can eliminate the need for drying equipment, which is normally required in the bonding process. Furthermore, irradiation with an appropriate amount of active energy rays can accelerate the curing rate, thereby improving production speed.

[0070] Examples of epoxy compounds include glycidyl ethers of aromatic compounds or chain compounds having a hydroxyl group, glycidyl aminations of compounds having an amino group, epoxidized compounds of chain compounds having a C—C double bond, and alicyclic epoxy compounds in which a glycidyloxy group or an epoxyethyl group is bonded directly to a saturated carbon ring or via an alkylene, or in which an epoxy group is bonded directly to a saturated carbon ring. Other types of epoxy compounds may also be used in combination. Among these, alicyclic epoxy compounds are preferred because of their excellent cationic polymerizability.

[0071] The thickness of the adhesive layer may be determined appropriately depending on the type of resin that acts as an adhesive, the adhesive strength, the environment in which the adhesive is used, etc. The adhesive layer preferably has a thickness of 0.01 μm to 50 μm, more preferably 0.05 μm to 20 μm, and even more preferably 0.1 μm to 10 μm.

[0072] In the polarizing plate according to one embodiment of the present invention, a retardation layer 130 may be further laminated on the other surface of the polarizer 110 as shown in FIG.

[0073] The retardation layer 130 may be, for example, a stretched or non-stretched polymer film, and may also be a liquid crystal layer obtained by curing a reactive liquid crystal compound.

[0074] For example, when the retardation layer 130 is made of a liquid crystal layer, a reactive liquid crystal compound (RM) that has optical anisotropy and is crosslinkable by light or heat may be used.

[0075] The retardation layer 130 may have a single-layer structure or a multi-layer structure in which two or more layers are laminated. For example, the retardation layer 130 may have a laminated structure such as a positive C plate layer, a combination of a positive C plate layer and a negative B plate layer, a combination of a positive uniaxial retardation film and a positive C plate layer, or a combination of a negative biaxial retardation film and a positive C plate layer. In this case, the layers constituting the retardation layer may be bonded to each other via an adhesive or may be directly laminated to each other by coating.

[0076] The retardation layer 130 may have an in-plane retardation (R0) of 0 to 10 nm at a wavelength of 550 nm. When the in-plane retardation (R0) of the retardation layer at a wavelength of 550 nm is in this range, a wide viewing angle and improved color gamut can be achieved.

[0077] The polarizer 110 and the retardation layer 130 may be attached to each other via an adhesive.

[0078] The pressure-sensitive adhesive may be any of various pressure-sensitive adhesives or adhesives known in the art, and the type is not particularly limited.

[0079] Examples of the adhesive include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, cellulose-based adhesives, and vinyl alkyl ether-based adhesives.

[0080] The adhesive may be a photocurable adhesive, but the type is not particularly limited.

[0081] The photocurable adhesive exhibits strong adhesive strength by crosslinking and curing when exposed to active energy rays such as ultraviolet (UV) and electron beam (EB), and may be composed of a reactive oligomer, a reactive monomer, a photopolymerization initiator, etc.

[0082] The reactive oligomer is an important component that determines the properties of the adhesive, and forms a polymer bond through a photopolymerization reaction to form a cured coating. Usable reactive oligomers include polyester resins, polyether resins, polyurethane resins, epoxy resins, polyacrylic resins, and silicone resins.

[0083] The reactive monomer acts as a crosslinking agent or diluent for the reactive oligomer, and affects adhesive properties. Usable reactive monomers include monofunctional monomers, polyfunctional monomers, epoxy-based monomers, vinyl ethers, cyclic ethers, etc.

[0084] The photopolymerization initiator absorbs light energy to generate radicals or cations to initiate photopolymerization, and may be selected according to the photopolymerizable resin.

[0085] 3, an adhesive layer 140 may be further laminated on the surface of the retardation layer 130 opposite to the surface facing the polarizer 110. The adhesive layer 140 may serve to attach the polarizer 100 to an OLED panel or a touch panel.

[0086] The adhesive layer 140 may be made using various adhesives well known in the art, and the type is not particularly limited.

[0087] Examples of the adhesive include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, cellulose-based adhesives, and vinyl alkyl ether-based adhesives.

[0088] The thickness of the adhesive layer 140 is preferably 5 to 30 μm, and more preferably 10 to 25 μm, so long as it is thin enough not to impair processability or durability. If the thickness of the adhesive layer 140 is less than 5 μm, it may not be possible to fill dents or scratches on the panel, resulting in visible defects. If the thickness exceeds 30 μm, it may be difficult to achieve a thinner polarizing plate.

[0089] In the polarizing plate according to an embodiment of the present invention, a peelable protective film (not shown) may be further laminated on the surface of the surface-treated film 120 opposite to the surface facing the polarizer 110 .

[0090] The peelable protective film includes a substrate and an adhesive layer formed on one side of the substrate. The adhesive layer is attached to a surface-treated film 120, and when a polarizing plate is attached to the cover window, the adhesive layer is peeled from the surface-treated film 120, allowing the protective film to be easily removed. The adhesive layer may be made of any of the adhesives listed above.

[0091] Examples of the substrate for the peelable protective film include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; and polyolefin films such as polypropylene and polyethylene.

[0092] The thickness of the peelable protective film may be 10 to 150 μm, preferably 25 to 130 μm. If the thickness of the peelable protective film is less than 10 μm, peeling of the protective film may be difficult, and if the thickness exceeds 150 μm, adhesion to the surface treatment film 120 may decrease.

[0093] In addition, in the polarizing plate according to an embodiment of the present invention, a release film (not shown) may be further laminated on the surface of the adhesive layer 140 opposite to the surface facing the retardation layer.

[0094] The release film is removed when the polarizing plate is attached to an OLED panel or a touch panel.

[0095] Examples of the substrate for the release film include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; and polyolefin films such as polypropylene and polyethylene.

[0096] The surface of the base material of the release film that comes into contact with the pressure-sensitive adhesive layer 140 may be subjected to a release treatment. The release treatment may be performed using a release agent such as a silicon-based release agent, a fluorine-based release agent, or a long-chain alkyl graft polymer-based release agent, or a surface treatment method using plasma treatment.

[0097] The thickness of the release film may be 10 to 150 μm, preferably 25 to 130 μm. If the thickness of the release film is less than 10 μm, the release film may not be easily peeled off, and if the thickness exceeds 150 μm, the adhesion to the pressure-sensitive adhesive layer 140 may decrease.

[0098] The polarizing plate according to one embodiment of the present invention may have a total thickness of 130 to 220 μm, preferably 145 to 160 μm, excluding the thickness of the peelable protective film and the release film.

[0099] One embodiment of the present invention relates to an image display device including the polarizing plate 100.

[0100] The image display device according to one embodiment of the present invention is applicable not only to ordinary liquid crystal display devices but also to various other image display devices such as organic EL display devices, plasma display devices, and field emission display devices.

[0101] The image display device may further include components known in the art in addition to the polarizing plate. [Example]

[0102] The present invention will be described in more detail below with reference to examples and experimental examples. However, it will be obvious to those skilled in the art that these examples and experimental examples are merely for the purpose of illustrating the present invention and do not limit the scope of the present invention.

[0103] Production Example 1: Production of composition for forming antiglare layer A composition for forming an antiglare layer was prepared by blending 14 wt% of urethane acrylate (Miwon Corporation, SC2153), 15 wt% of pentaerythritol triacrylate (Miwon Corporation, M340), 1 wt% of light-transmitting particles (acrylic-styrene copolymer, refractive index 1.525, average particle size 2 μm), 67 wt% of ethyl acetate as a solvent, 2.5 wt% of a photoinitiator (Ciba Corporation, I-184), and 0.5 wt% of a leveling agent (BYK Chemie Corporation, BYK3550) using a mixer and filtering the mixture using a PP filter.

[0104] Manufacturing Example 2: Manufacturing of polarizer A transparent, unstretched polyvinyl alcohol film with a thickness of 75 μm and a saponification degree of 99.9% or higher was humidified to a moisture content of 4%. It was then first stretched at a 4.5x stretch ratio using a heated roll stretching method at 120°C, and then immersed in 50°C deionized water for 1 minute to swell. It was then dyed by immersing it in a dyeing solution containing 5.0 mmol / L iodine and 4 wt% potassium iodide at 30°C for 1 minute. During the swelling and dyeing steps, the film was stretched to 0.9x and 1.1x, respectively. It was then crosslinked by immersing it in a crosslinking solution containing 10 wt% potassium iodide and 7 wt% boric acid at 70°C for 3 minutes. It was stretched to 1.2x in the crosslinking step. After crosslinking was complete, the polyvinyl alcohol film was dried in an oven at 70°C for 4 minutes to produce a polarizer.

[0105] Production Examples 1 to 3 and Production Comparative Examples 1 to 6: Production of Surface-Treated Films The antiglare layer-forming composition of Preparation Example 1 was coated onto a substrate film to a wet thickness of 23 μm, and the solvent was then dried at 80° C. for 2 minutes. The dried film was irradiated with UV light at an integrated dose of 400 mJ / cm to prepare an antiglare film as a surface-treated film. The films shown in Table 1 below were used as the substrate film.

[0106] Examples 1 to 3 and Comparative Examples 1 to 6: Production of polarizing plates A polarizing plate having the same structure as the embodiment shown in FIG. 1 was produced according to the following method.

[0107] The polarizer prepared in Preparation Example 2 was attached to the substrate film of the surface-treated film prepared in Preparation Example and Preparation Comparative Example using an acrylic UV-curable adhesive. Then, a polarizing plate was produced by irradiating the film with UV light at an integrated light dose of 400 mJ / cm.

[0108] Experimental Example: The physical properties of the surface-treated films manufactured in the above Manufacturing Examples and Manufacturing Comparative Examples and the polarizing plates manufactured in the Examples and Comparative Examples were measured by the following methods, and the results are shown in Table 1 below.

[0109] (1) Moisture permeability of surface-treated film For the surface-treated films produced in the Production Examples and Production Comparative Examples, the amount of water vapor (g, change in sample weight) passing through each sample with an area of ​​1 m for 24 hours was measured in accordance with the moisture permeability test (cup method) of JIS Z 0208 under an environment of a temperature of 40°C and a relative humidity of 90%.

[0110] (2) Tensile strength of polarizing plate The polarizing plates of the Examples and Comparative Examples were cut to a width of 5 mm with the long side in the MD direction, and the gauge length was set to 50 mm. Using a tensile strength measuring device (UTM autograph, Shimadzu Corporation, Model No. AG-X 1KN), the value until the sample broke was measured at a measurement speed of 4 mm / min, and the maximum value was used to evaluate the tensile strength.

[0111] (3) Deflection 320mm x 180mm x 0.7mm glass one side The polarizing plates of the Examples and Comparative Examples were laminated on the laminate, and then left to stand for 100 hours under moist heat resistant conditions (60°C, relative humidity 90%). An acrylic adhesive (manufactured by Lintec Corporation) with a thickness of 15 μm was used as the adhesive layer for laminating the polarizing plates.

[0112] The amount of deflection of the sample after being left standing was measured using Premium-600C manufactured by Inteck IMS.

[0113] (4) Curl of polarizing plate The polarizing plates of the examples and comparative examples were cut into pieces measuring 700×300 mm with the long sides in the MD direction, and placed on a flat plate, and the maximum height from the reference surface was measured.

[0114] The curl value can be obtained by placing the polarizing plate so that its convex surface is in contact with a reference surface and then measuring the average height from the reference surface to the four corners, with a (+) value representing positive curl and a (-) value representing reverse curl. When the polarizing plate is placed so that its convex surface is in contact with the reference surface, positive curl occurs when the surface-treated film is located above the polarizer, and reverse curl occurs when the surface-treated film is located below the polarizer.

[0115] [Table 1]

[0116] As shown in Table 1, the polarizing plates of Examples 1 to 3 according to the present invention, which satisfied 70≦a×b / c≦300, exhibited positive curl and a small deflection of less than 1.3 mm when applied to glass.

[0117] On the other hand, the polarizing plates of Comparative Examples 1 and 3 to 6, in which the a×b / c value was less than 70, showed an increased amount of deflection, and the polarizing plate of Comparative Example 2, in which the a×b / c value was more than 300, showed reverse curling.

[0118] Therefore, it was found that the polarizing plates of Examples 1 to 3 were able to control the bending characteristics of large panels without causing reverse curling, and thus reduce the occurrence of light leakage, compared to the polarizing plates of Comparative Examples 1 to 6.

[0119] Although specific aspects of the present invention have been described in detail above, it will be apparent to those skilled in the art that these specific descriptions are merely preferred embodiments and are not intended to limit the scope of the present invention. Those skilled in the art will be able to make various applications and modifications within the scope of the present invention based on the above content.

[0120] Therefore, the true scope of the invention is to be defined by the following claims and their equivalents. [Explanation of symbols]

[0121] 110: Polarizer 120: Surface treatment film 121: Base film 122: Surface treatment layer 130: Retardation layer 140: Adhesive layer

Claims

1. A polarizing plate comprising a polarizer and a surface-treated film laminated on one surface of the polarizer, The polarizer is manufactured by adsorbing iodine onto a polyvinyl alcohol film and uniaxially stretching the film, and has a thickness of 5 μm to 30 μm; The surface-treated film comprises a substrate film having a surface-treated layer formed on at least one surface thereof, the base film is made of a (meth)acrylic film, The thickness of the substrate film is 60 μm to 100 μm, The moisture permeability of the surface-treated film is 70 g / m ２ / 24 hr or less, The polarizing plate has a tensile strength of 85 MPa to 150 MPa; A polarizing plate that satisfies the following mathematical formula 1. [Mathematical formula 1] 70≦a×b / c≦300 In the above formula, a is the thickness of the substrate film (μm), b is the tensile strength of the polarizing plate (Mpa), c is the moisture permeability (g / m) of the surface-treated film ２ / 24hr).

2. The polarizing plate according to claim 1 , wherein the surface treatment layer is a hard coating layer or an anti-glare coating layer.

3. An image display device comprising the polarizing plate according to claim 1 or 2.

Images