Polarizing plate and optical display device

Abstract

Provided are a polarizing plate and an optical display device including the same, which comprises a polarizer, and a first optical functional layer and a second optical functional layer sequentially laminated on one surface of the polarizer, wherein the first optical functional layer contains anisotropic particles, the anisotropic particles including acicular particles, and the acicular particles are oriented in the in-plane direction of the first optical functional layer, and when the light absorption axis of the polarizer is set to 0°, the average orientation angle between the light absorption axis of the polarizer and the longitudinal direction of the acicular particles is -10° to +10°, and the standard deviation of the orientation angle is 15° or less, and the second optical functional layer contains a cured product of a composition including an active energy ray-curable resin.

Description

[Technical Field]

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

[0002] The liquid crystal display device has a structure in which a viewer-side polarizing plate, a liquid crystal panel, and a light source-side polarizing plate are laminated in this order.

[0003] In some cases, a liquid crystal display device with high visibility and brightness on the side is preferred. To provide high visibility and brightness, one method is to add a visibility-improving layer, which includes two resin layers with different refractive indices and has a pattern formed at the interface between the resin layers, to the viewer-side polarizing plate. However, in some cases, a polarizing plate that can improve visibility without including such a visibility-improving layer is preferred.

[0004] On the other hand, since the viewer-side polarizing plate is disposed at the outermost periphery of the LCD device, it is inevitably vulnerable to external impacts. Therefore, the viewer-side polarizing plate must also have high hardness. For example, a polarizing plate with a pencil hardness of 2H or more can be used as the viewer-side polarizing plate.

[0005] The background art of the present invention is disclosed in Korean Patent Publication No. 2018-0047569 and the like. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Korean Patent Publication No. 2018-0047569 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a polarizing plate that has a visibility improving effect even without a pattern, for example, a visibility improving pattern itself or a visibility improving layer having a pattern.

[0008] Another object of the present invention is to provide a polarizing plate having excellent hardness.

[0009] A further object of the present invention is to provide a polarizing plate having the effect of reducing the thickness.

[0010] It is still another object of the present invention to provide a polarizing plate which has the effect of reducing the occurrence of curling of the polarizing plate. [Means for solving the problem]

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

[0012] 1. A polarizing plate includes a polarizer, and a first optical functional layer and a second optical functional layer sequentially laminated on one side of the polarizer, wherein the first optical functional layer includes anisotropic particles, the anisotropic particles including acicular particles, and the acicular particles are oriented in the in-plane direction of the first optical functional layer, and when the light absorption axis of the polarizer is set to 0°, the average orientation angle between the light absorption axis of the polarizer and the longitudinal direction of the acicular particles is -10° to +10°, and the standard deviation of the orientation angle is 15° or less, and the second optical functional layer includes a cured product of a composition including an active energy ray-curable resin.

[0013] In 2.1, the first optical functional layer may be a contrast or brightness improving layer.

[0014] In 3.1-2, the upper and lower surfaces of the second optical functional layer may each be entirely flat.

[0015] In 4.1-4, the acicular particles may be acicular microparticles.

[0016] In 5.1-4, the needle-shaped particles may be formed of one or more of titanium oxide, zirconium oxide, zinc oxide, calcium carbonate, boehmite, aluminum borate, calcium silicate, magnesium sulfate, magnesium sulfate hydrate, and potassium titanate.

[0017] In 6.1-5, the acicular particles may have an average aspect ratio of 5 to 60.

[0018] In 7.1-6, the needle-shaped particles may be contained in the first optical functional layer in an amount of 1% by weight to 30% by weight.

[0019] In 8.1-7, the first optical functional layer may include a matrix in which the needle-shaped particles are impregnated.

[0020] In 9.8, the matrix may be adhesive or non-adhesive.

[0021] In 10.8-9, the matrix has a glass transition temperature of -10°C or less and a storage modulus of 1 x 10 at 25°C. -3 MPa to 9×10 -1 It may be MPa.

[0022] In 11.1-10, the active energy ray curable resin may include a resin having a vinyl group or a (meth)acrylate group.

[0023] In 12.1-11, the refractive index of the matrix in the first optical functional layer minus the refractive index of the second optical functional layer may be 0.1 or less.

[0024] In 13.1-12, the second optical functional layer may be thinner than the first optical functional layer.

[0025] In 14.1-13, the polarizing plate may include at least one of a protective layer, an adhesive layer, an adhesive layer, a functional film, and a functional coating layer.

[0026] In 15.14, the functional film and the functional coating layer may be an anti-glare layer, an anti-reflection layer, an ultra-low reflection layer, a low refractive index layer, a high refractive index layer, or an anti-fingerprint layer, respectively.

[0027] Another aspect of the present invention is an optical display device.

[0028] An optical display device includes the polarizing plate of the present invention. [Effects of the Invention]

[0029] The present invention can provide a polarizing plate that has a visibility improving effect even without including a pattern, for example, a visibility improving pattern itself or a visibility improving layer having a pattern.

[0030] The present invention can provide a polarizing plate having excellent hardness.

[0031] The present invention can provide a polarizing plate having a thinning effect.

[0032] The present invention can provide a polarizing plate that has the effect of reducing curling of the polarizing plate. [Brief explanation of the drawings]

[0033] [Figure 1] 1 is a TEM photograph of a plurality of needle-shaped particles used in the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view of an acicular particle. [Figure 3] 1 is a schematic diagram showing the distribution of angles formed by the length direction of acicular particles with respect to a reference when the light absorption axis of a polarizer is set at 90° with respect to the reference. [Figure 4] 1 is an enlarged photograph of the orientation of needle-shaped particles in a first optical functional layer according to an example of the present invention. [Figure 5] 10 shows the results of the distribution of orientation angles actually measured for the first optical functional layer of one example of the present invention. [Figure 6] FIG. 2 is a perspective view of a first optical functional layer according to an embodiment of the present invention. [Figure 7] FIG. 2 is a perspective view of a first optical functional layer and a second optical functional layer according to an embodiment of the present invention. [Figure 8] FIG. 1 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention. [Figure 9] FIG. 1 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention. [Figure 10] FIG. 1 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention. [Figure 11] FIG. 1 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention. [Figure 12] FIG. 1 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0034] The present invention may be embodied in various different forms and is not limited to the embodiments set forth herein.

[0035] 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 the context clearly indicates otherwise.

[0036] In the drawings, parts that are not relevant to the description are omitted in order to clearly explain the present invention, and the same reference numerals are used throughout the specification to refer to the same or similar components.

[0037] In this specification, "upper" and "lower" are defined with reference to the drawings, and "upper" may be changed to "lower" and "lower" to "upper" depending on the viewpoint. "Up" may include not only directly on but also cases where other structures are interposed between them. Meanwhile, "directly on," "directly on," "directly formed," or "formed in direct contact with" means that no other structures are interposed between them.

[0038] In this specification, the "in-plane retardation (Re)" is a value at a wavelength of 550 nm and is expressed by the following mathematical formula A. [Number A] Re=(nx-ny)×d (In the above formula A, nx and ny are the refractive indices of the protective layer in the slow axis direction and fast axis direction, respectively, at a wavelength of 550 nm, and d is the thickness of the protective layer (unit: nm).)

[0039] In this specification, "(meth)acrylic" means acrylic and / or methacrylic.

[0040] In this specification, the "refractive index" may be a value measured at a wavelength of 380 nm to 780 nm, specifically at 550 nm.

[0041] In this specification, "light transmittance" may be a value measured at a wavelength of 380 nm to 780 nm, specifically at 550 nm.

[0042] In this specification, the "storage modulus" of a matrix is ​​a value measured at 25°C while heating the test piece in a temperature range of 0°C to 100°C (heating rate: 10°C / min) using a storage modulus measuring device (ARES, Advanced Rheometry Expansion System, TA instrument) after applying a matrix composition onto a release film, drying it at 95°C for 4 minutes, and reducing the thickness to 50 μm to form a matrix on the release film. The matrix is ​​then laminated to a thickness of 500 μm and cut into a circle with a diameter of 8 mm to prepare a test piece.

[0043] In this specification, the "glass transition temperature" of a matrix is ​​a value measured using a Discovery (TA Instruments) by preparing 15 mg of matrix (on 6 mm Al pan), heating it to 180°C at a heating rate of 20°C / min in a nitrogen atmosphere (flow rate of 50 mL / min), cooling it to -100°C, and then heating it to 100°C at a heating rate of 10°C / min. In this case, the matrix may be one produced by the method described above.

[0044] In this specification, when describing a range of values, "X to Y" means "X≦and≦Y".

[0045] The polarizing plate of the present invention provides a visibility-improving effect even without a visibility-improving layer including a pattern or a resin layer having a pattern at its interface. The polarizing plate of the present invention provides excellent hardness. The present invention provides a thinning effect. The present invention provides a polarizing plate that reduces curling of the polarizing plate, and can further have the effect of reducing cracking on the surface of the polarizing plate.

[0046] The polarizing plate of the present invention comprises a polarizer, and a first optical functional layer and a second optical functional layer sequentially laminated on one side of the polarizer, wherein the first optical functional layer contains anisotropic particles, the anisotropic particles including acicular particles, and the acicular particles are oriented in the in-plane direction of the first optical functional layer, and when the light absorption axis of the polarizer is set to 0°, the average orientation angle between the light absorption axis of the polarizer and the longitudinal direction of the acicular particles is -10° to +10°, and the standard deviation of the orientation angle is 15° or less, and the second optical functional layer contains a cured product of a composition containing an active energy ray-curable resin.

[0047] A polarizing plate according to one embodiment of the present invention will be described below.

[0048] The polarizing plate includes a polarizer, a first optical functional layer, and a second optical functional layer. The first optical functional layer may be different from the second optical functional layer in terms of whether or not it contains anisotropic particles, thickness, composition, and / or function.

[0049] The polarizing plate may have a light transmittance of 95% or more, for example, 96% to 100%, and in this range, the polarizing plate can be used as a viewer-side polarizing plate.

[0050] First optical functional layer The first optical functional layer may be laminated on a light exit surface of the polarizer. The "light exit surface" is a surface from which internal light of the backlight unit reaches the polarizer and exits the polarizer. The first optical functional layer includes anisotropic particles.

[0051] The anisotropic particles include acicular particles. The present invention includes acicular particles among various types of anisotropic particles. The present invention utilizes the fact that the acicular particles have different degrees of diffusion of light incident from a backlight unit, for example, a polarizer, depending on the refractive index and orientation direction of the particles, thereby achieving particularly excellent effects of improving visibility and brightness ratio.

[0052] The needle-shaped particles are oriented in the in-plane direction of the first optical functional layer, and when the light absorption axis of the polarizer is set to 0°, the average value of the orientation angle between the light absorption axis of the polarizer and the longitudinal direction of the needle-shaped particles is -10° to +10°, and the standard deviation of the orientation angle is 15° or less. Within the above average value and standard deviation ranges, the polarizing plate can improve the brightness and / or luminance at the front and side. Therefore, the first optical functional layer can function as a brightness and / or visibility and / or luminance improving layer.

[0053] As described below, the upper and lower surfaces of the first optical functional layer are entirely flat and unpatterned. Nevertheless, the first optical functional layer contains the acicular particles and satisfies the average orientation angle and standard deviation of the orientation angle of the present invention, thereby improving front and side visibility, contrast ratio, and / or brightness. This eliminates the need for an optical pattern or pattern layer, which can improve the manufacturing process of the polarizing plate and promotes the provision of a thinner thickness.

[0054] The needle-shaped particles will be described in detail below.

[0055] Figure 1 is a TEM photograph of a plurality of needle-shaped particles used in the present invention, and Figure 2 is a schematic cross-sectional view of the needle-shaped particles.

[0056] The needle-shaped particles have a length L and a predetermined cross-sectional diameter D, and the cross-sectional diameter D may not be uniform over the entire length L, but may decrease toward both ends of the needle-shaped particle. Needle-shaped particles with non-uniform thickness exhibit optical anisotropy, allowing light incident from a polarizer to exit in different directions when passing through the needle-shaped particle.

[0057] 2 shows the case where the cross-sectional diameter of an acicular particle decreases from the center to both ends. However, depending on the manufacturing method of the acicular particle, the cross-sectional diameter may be uniform at one end and decrease toward the other end.

[0058] The needle-shaped particles may preferably be needle-shaped microparticles having a length L measured in micrometers. Here, "measured in micrometers" means that the length L is at least 1 μm or more. This allows for easy control of the mean and standard deviation of the orientation angle of the needle-shaped microparticles in the present invention, thereby promoting improvements in light-dark ratio and brightness. Nanoparticles (e.g., nanorods, needle-shaped nanoparticles) having a length L measured in nanometers (e.g., nanorods, needle-shaped nanoparticles) are difficult to align in the present invention, making it difficult to achieve the effects of the present invention. Furthermore, if an excessive amount is used to achieve the same effect, optical properties such as light transmittance and haze may be poor.

[0059] In one embodiment, the length L may be 10 μm to 50 μm, for example, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 10 μm to 30 μm, or 15 μm to 28 μm. Within this range, the acicular particles of the present invention can be easily oriented, which can promote improvements in the contrast ratio and brightness.

[0060] In one embodiment, the cross-sectional diameter D may be 0.5 μm to 2.0 μm, for example, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2.0 μm, or 1 μm to 2.0 μm. Within this range, the aspect ratio increases, and a lateral diffusion effect may occur. The "cross-sectional diameter" refers to the cross-sectional diameter of an acicular particle and may refer to the maximum diameter measured across the cross section of the acicular particle.

[0061] In one embodiment, the cross section of the needle-shaped particles may be circular, elliptical, or the like.

[0062] The acicular particles may have an average aspect ratio of 5 to 60. This range can easily provide the effects of improving the contrast and brightness of the present invention. For example, the average aspect ratio may be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 10 to 50, or 10 to 18. The "average aspect ratio" means the average value of the aspect ratios measured for each of the acicular particles, and the "aspect ratio" means the ratio of the length to the maximum cross-sectional diameter of the acicular particles.

[0063] The acicular particles are oriented in the in-plane direction of the optically functional layer, with an average orientation angle of -10° to +10° and a standard deviation of 15° or less. The "orientation angle" refers to the angle between the light absorption axis of the polarizer and the length direction of the acicular particles when the light absorption axis of the polarizer is set to 0°. Spherical particles, particularly isotropic particles, have a spherical shape, but spherical particles have no length direction and therefore no orientation angle.

[0064] By setting the average orientation angle between -10° and +10° and the standard deviation of the orientation angle to 15° or less, light incident from the polarizer is emitted in different directions when passing through the acicular particles, improving the contrast and brightness of the front and side views. Therefore, the first optical functional layer may be a contrast and / or visibility improving layer. The light absorption axis of the polarizer may be in the MD (machine direction) of the polarizer.

[0065] The mean and standard deviation of the orientation angles will be explained with reference to FIGS.

[0066] Figure 3 is a schematic diagram showing the distribution of angles made by the length direction of acicular particles with respect to a reference when the light absorption axis of a polarizer is set at 90° with respect to the reference, Figure 4 is an enlarged photograph of the orientation of acicular particles in the first optical functional layer of one embodiment of the present invention, and Figure 5 shows the distribution of orientation angles actually measured for the first optical functional layer of one embodiment of the present invention.

[0067] (The average value obtained by averaging the angles -90°) is the average value of the orientation angle of the present invention. For example, if (the average value obtained by averaging the angles) is 80°, the average value of the orientation angle is -10°, and if (the average value obtained by averaging the angles) is 100°, the average value of the orientation angle is +10°. The standard deviation can be calculated through the distribution in the usual way.

[0068] In one embodiment, the average value of the orientation angle is, for example, -10°, -9.5°, -9°, -8.5°, -8°, -7.5°, -7°, -6.5°, -6°, -5.5°, -5°, -4.5°, -4°, -3.5°, -3°, -2.5°, -2°, -1.5°, -1°, -0.5°, 0°, +0.5°, +1°, +1.5°, +2°, +2.5°, +3°, +3.5°, +4°, +4.5°, +5°, +5.5°, +6°, +6.5°, +7°, +7.5°, +8°, ​​+8.5°, +9°, + 9.5°, +10°, for example, -4.0° to +4.0°, for example, -2.5° to +2.5°, and the standard deviation of the orientation angle may be, for example, 0°, 0.5°, 1°, 1.5°, 2°, 2.5°, 3°, 3.5°, 4°, 4.5°, 5°, 5.5°, 6°, 6.5°, 7°, 7.5°, 8°, 8.5°, 9°, 9.5°, 10°, 10.5°, 11°, 11.5°, 12°, 12.5°, 13°, 13.5°, 14°, 14.5°, 15°, 0° to 8.5°, or 5° to 8.5°. Within these ranges, the effects of the present invention may be further improved.

[0069] In one embodiment, at least 90%, for example, 95% to 100%, of the acicular particles in the first optical functional layer are aligned with an orientation angle of -10° to +10°. This range can achieve a uniform contrast and improved visibility. Here, "%" refers to the weight ratio of acicular particles with an orientation angle of -10° to +10° to the total weight of the acicular particles contained in the first optical functional layer.

[0070] The needle-shaped particles may have a refractive index of 1.5 to 2.2, for example, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 1.6 to 1.8, for example, 1.65 to 1.7. Within this range, the particles have an appropriate refractive index compared to the resin layer (or matrix) described below, which can promote improvements in the contrast ratio and visibility.

[0071] The acicular particles may be organic particles, inorganic particles, or organic / inorganic particles. For example, the acicular particles may be metal oxides such as titanium oxide (e.g., TiO2), zirconium oxide (e.g., ZrO2), zinc oxide (e.g., ZnO), calcium carbonate (CaCO3), boehmite, aluminum borate (e.g., AlBO3), calcium silicate (e.g., CaSiO3, wollastonite), magnesium sulfate (MgSO4), magnesium sulfate hydrate (e.g., MgSO4·7H2O), potassium titanate (e.g., K2Ti8O), etc. 17 The particles may be formed of one or more of metal compounds such as cellulose acetate, inorganic particles such as glass, and organic particles such as synthetic resin. In one embodiment, needle-shaped particles formed of calcium carbonate can easily realize the effects of the present invention and can be easily produced.

[0072] The acicular particles may be included in the first optical functional layer without being surface-modified. However, surface-modified acicular particles can further enhance compatibility with the organic material matrix and particle dispersibility, as described below, thereby improving the optical properties of the first optical functional layer and preventing particle aggregation, thereby easily achieving the effects of the present invention. More than 50% of the total surface area of ​​the acicular particles, for example, 60% to 100%, or 60% to 95%, may be surface-modified. Within these ranges, improved compatibility and dispersibility can be achieved.

[0073] In one embodiment, the surfaces of the acicular particles may be modified with one or more of a silane compound, a surfactant, and an oil. For example, the acicular particles may be surface-treated with a silane compound having a (meth)acryloyloxy group or a (meth)acrylate group, which may provide excellent compatibility and dispersibility with the matrix of the resin layer formed from the active energy ray-curable composition described below.

[0074] The silane-based compound having a (meth)acryloyloxy group or a (meth)acrylate group may include one or more of 3-(meth)acryloyloxypropylmethyldimethoxysilane, 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, 3-(meth)acryloyloxypropyltrimethoxysilane, for example, 3-(meth)acryloyloxypropyltrimethoxysilane, and 3-(meth)acryloyloxypropyltriethoxysilane.

[0075] The acicular particles may account for 90% or more, for example, 95% to 100%, or 100% of the total anisotropic particles contained in the first optical functional layer. Within this range, the effects of the present invention can be easily achieved. Here, "%" refers to the weight ratio of the acicular particles to the total weight of the anisotropic particles contained in the first optical functional layer.

[0076] The anisotropic particles, e.g., acicular particles, may be contained in the first optical functional layer in an amount of 1 to 30% by weight, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 3 to 15, or 4 to 10% by weight. This range can improve the contrast ratio and brightness and prevent the problem of increased haze in the polarizing plate caused by excessive content.

[0077] The first optical functional layer may contain only needle-shaped particles, but the needle-shaped particles may be impregnated in a matrix due to the bonding relationship between the polarizer and the protective layer in the polarizing plate, the mechanical strength of the polarizing plate, etc.

[0078] Referring to FIG. 6, the first optical functional layer 10 includes needle-shaped particles 1 and a matrix 2 , and the needle-shaped particles 1 may be impregnated within the matrix 2 .

[0079] The matrix 2 and the anisotropic particles, e.g., acicular particles 1, may have the same or different refractive indices. For example, if the difference between these two refractive indices is small, problems such as increased haze may be eliminated. For example, (the refractive index of the anisotropic particles, e.g., acicular particles - the refractive index of the matrix) may be 0.5 or less, e.g., 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.3 or less, e.g., 0 to 0.2.

[0080] In one embodiment, the matrix 2 may be an adhesive or non-adhesive layer.

[0081] The matrix 2 may be a cured product of a composition containing at least one of a thermosetting resin and an active energy ray-curable resin.

[0082] The thermosetting resin is a resin that is cured by drying and / or heat treatment, and may include, for example, a resin having a thermosetting reactive group such as a (meth)acrylate group, an epoxy group, a urethane group, or a urethane (meth)acrylate group. For example, the thermosetting resin may be a (meth)acrylic resin. Although not necessarily required, a matrix formed from a composition containing the thermosetting resin may be an adhesive layer.

[0083] The active energy ray-curable resin is a resin that is cured by ultraviolet rays, including UV rays, and may include, for example, a resin having a photocurable reactive group. For example, the photocurable reactive group may be a vinyl group, a (meth)acrylate group, or the like, and the active energy ray-curable resin may have one or more of the photocurable reactive groups. For example, the active energy ray-curable resin may be selected from (meth)acrylate-based, urethane (meth)acrylate-based, epoxy (meth)acrylate-based, silicone (meth)acrylate-based, and other resins that can realize the effects of the present invention.

[0084] The composition may further include an initiator for curing one or more of the thermosetting resin and the active energy ray-curable resin. For example, the initiator may be one or more of a thermal initiator and a photoinitiator. The thermal initiator may be an azo-based initiator, a peroxide-based initiator, or the like. The photoinitiator may be a photoradical initiator such as a phosphorus-based initiator, a phosphine oxide-based initiator, a ketone-based initiator, or a cyclohexyl ketone-based initiator.

[0085] The composition may include one or more of a heat-curable crosslinking agent and a photo-curable crosslinking agent. The heat-curable crosslinking agent may be an isocyanate-based, epoxy-based, amine-based, or other crosslinking agent. The photo-curable crosslinking agent may be a multifunctional photo-curable monomer having two or more photo-curable reactive groups.

[0086] The composition may contain conventional additives known to those skilled in the art, such as surface modifiers, antistatic agents, dispersants, dyes, pigments, and the like.

[0087] In one specific example, the first optical functional layer or matrix may be an adhesive layer so that the first optical functional layer can be directly laminated to a protective layer or a polarizer described below without using an interlayer adhesive. If the first optical functional layer or matrix is ​​formed of a composition containing an active energy ray-curable resin, it becomes a non-adhesive layer, and an interlayer adhesive is additionally required when adhering the first optical functional layer to a protective layer or a polarizer described below, which can cause a problem of reduced light transmittance of the polarizing plate.

[0088] A method for orienting anisotropic particles, for example, needle-shaped particles, in the first optical functional layer will be described below.

[0089] The first optical functional layer may be manufactured by applying a composition for the first optical functional layer to an adherend and then curing it. In this case, the average orientation angle and standard deviation of the orientation angle of the present invention may be realized by adjusting the viscosity of the composition for the first optical functional layer. The average orientation angle and standard deviation of the orientation angle may be realized by adjusting the application pressure, etc., when applying the composition.

[0090] If the viscosity of the composition for the first optical functional layer is too high, the acicular particles may not be reliably oriented during the coating process, or even if they are oriented, the average orientation angle and standard deviation of the orientation angle of the present invention may not be easily achieved. Therefore, the viscosity of the composition for the first optical functional layer must not be too high. The desired viscosity may vary depending on the content and length of the acicular particles in the first optical functional layer.

[0091] In particular, when the first optical functional layer is an adhesive layer, the composition for the first optical functional layer essentially contains an adhesive resin. The viscosity of the composition for the first optical functional layer is determined by various variables in the composition, but may generally be determined by the weight-average molecular weight of the adhesive resin, which accounts for the majority of the solid content of the composition. To achieve an appropriate viscosity, the weight-average molecular weight of the adhesive resin should not be significantly increased, which may result in a decrease in the hardness of the final first optical functional layer. As a result, the glass transition temperature of the matrix is ​​preferably −10°C or lower, for example, −70°C, −65°C, −60°C, −55°C, −50°C, −45°C, −40°C, −35°C, −30°C, −25°C, −20°C, −10°C, −70°C to −10°C, −70°C to −15°C, or a storage modulus of 1×10 at 25°C. -3 MPa to 9×10 -1 MPa, e.g., 1 x 10 -3 MPa, 1×10 -2 MPa, 1×10 -1 MPa, 9 x 10 -1 It may be MPa.

[0092] The polarizing plate of the present invention has a second optical functional layer (described below) additionally laminated on one side (e.g., the light-emitting side) of a first optical functional layer that satisfies the average orientation angle and standard deviation of the orientation angle of the present invention. The second optical functional layer can perform a function different from that of the first optical functional layer.

[0093] In one specific example, the second optical functional layer acts as a hardness improving layer to provide the polarizing plate with excellent hardness. To increase hardness, a method of laminating a hard coating layer or hard coating film on the upper surface of the protective layer without using the second optical functional layer described below can be considered, but this can lead to problems such as a large thickness imbalance on both sides of the polarizer, causing curling of the polarizing plate.

[0094] In one embodiment, the polarizing plate may have a pencil hardness of 2H or more, for example, 2H to 4H, as measured by the ASTM D3502 method. In this range, the polarizing plate can withstand external impacts and can be used satisfactorily as a viewer-side polarizing plate.

[0095] In one specific example, "curl" can be measured by preparing a test specimen by cutting a polarizing plate to a predetermined size, placing the test specimen with the second optically functional layer at the top, and then measuring the maximum distance from the bottom to the test specimen. The shorter the maximum distance, the less curl occurs. "Curl" may be measured at room temperature (e.g., 23°C to 25°C), or after leaving the specimen at a high temperature (e.g., 60°C to 80°C) or at a high temperature and high humidity (e.g., 60°C to 80°C and 95% relative humidity) for a long period of time (e.g., 100 to 500 hours).

[0096] The second optical functional layer may include a cured product of a composition for the second optical functional layer that includes an active energy ray-curable resin. This allows the second optical functional layer to compensate for the low hardness of the first optical functional layer, thereby increasing the hardness of the entire polarizer. While it may be possible to use the same polymer resin as a conventional protective layer for the second optical functional layer, this approach presents a problem in that the resulting layer would have a relatively lower hardness than a layer formed by curing an active energy ray-curable resin, and would therefore need to be thicker.

[0097] The active energy ray-curable resin is a resin that is cured by ultraviolet rays, including UV rays, and may include, for example, a resin having a photocurable reactive group. For example, the photocurable reactive group may be a vinyl group, a (meth)acrylate group, or the like, and the active energy ray-curable resin may have one or more of the photocurable reactive groups. For example, the active energy ray-curable resin may be selected from (meth)acrylate-based, urethane (meth)acrylate-based, epoxy (meth)acrylate-based, silicone (meth)acrylate-based, and other resins that can realize the effects of the present invention.

[0098] The composition may further include a photoinitiator that cures one or more of the active energy ray-curable resins. For example, the photoinitiator may be a photoradical initiator such as a phosphorus-based, phosphine oxide-based, ketone-based, or cyclohexyl ketone-based initiator, or a photocationic initiator.

[0099] The composition may further contain conventional additives known to those skilled in the art, such as surface modifiers, antistatic agents, dispersants, dyes, pigments, and the like.

[0100] The second optical functional layer is optically transparent and may not affect the improvement of the contrast ratio and / or visibility achieved by the first optical functional layer. The second optical functional layer may have a light transmittance of 95% or more, for example, 95% to 100%. Within this range, the effect of the present invention may not be affected.

[0101] The second optical functional layer may have the same or different refractive index as the matrix in the first optical functional layer. For example, (refractive index of the matrix in the first optical functional layer - refractive index of the second optical functional layer) may be 0.1 or less, e.g., 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0 to 0.1. In this range, problems such as increased haze due to differences in refractive index and changes in the optical path at the interface may be eliminated.

[0102] The second optical functional layer may have a refractive index of 1.3 to 1.6, for example, 1.3 to 1.5. Within this range, the first and second optical functional layers may be easily manufactured.

[0103] The second optical functional layer may be an adhesive layer or a non-adhesive layer depending on the composition of the second optical functional layer containing the active energy ray-curable resin.

[0104] The second optical functional layer may have the same thickness as or a different thickness from the first optical functional layer. For example, the second optical functional layer may be thinner than the first optical functional layer, thereby providing a thickness reduction effect.

[0105] In one embodiment, the second optically functional layer may have a thickness of 5 μm to 50 μm, for example, 5 μm to 20 μm, or 5 μm to 15 μm.

[0106] The second optical functional layer may be formed by applying a composition for the second optical functional layer to one surface of the adherend, the protective layer, or the first optical functional layer, and then photocuring the composition. As the photocuring method and the application method, conventional methods known to those skilled in the art can be adopted.

[0107] FIG. 7 is a perspective view of a first optical functional layer and a second optical functional layer according to an embodiment of the present invention.

[0108] Referring to FIG. 7, the first optical functional layer 10 includes a matrix 2 and needle-shaped particles 1, but the second optical functional layer 20 does not need to include inorganic particles such as needle-shaped particles 1 or organic particles.

[0109] The upper and lower surfaces of the second optical functional layer 20 may each be entirely flat.

[0110] The laminate 30 of the first optical functional layer 10 and the second optical functional layer 20 may have a light transmittance of 95% or more, for example, 96% to 100%. In this range, the laminate 30 can be used as a viewer-side polarizing plate.

[0111] Polarizing plate In addition to the first optical functional layer and the second optical functional layer, the polarizing plate may further include one or more of a polarizer, a protective layer (including a retardation layer), an adhesive layer and / or a bonding layer, a functional film (including a functional coating layer), etc.

[0112] (i) Polarizer The polarizer is a linear light-absorbing polarizer that transmits only one direction of incident light and absorbs light perpendicular to the one direction, thereby providing a polarizing function.

[0113] The polarizer may be a polarizer manufactured by dyeing and stretching a polyvinyl alcohol (PVA)-based film, or a polyene-based polarizer manufactured by dehydrating a polyvinyl alcohol-based film.

[0114] The polarizer may have a thickness of 50 μm or less, for example, 5 μm to 30 μm, which may prevent the film from melting or breaking when stretched.

[0115] (ii) Protective layer The protective layer can protect the polarizer or increase the mechanical strength of the polarizing plate by being included in the polarizing plate. The protective layer may be an adherend on which the optically functional layer is formed.

[0116] The protective layer may include a transparent substrate. The transparent substrate may have a refractive index higher or lower than that of the optically functional layer. For example, the transparent substrate may have a refractive index higher than that of the optically functional layer. This can facilitate improvement of the contrast ratio and brightness.

[0117] The transparent substrate may include an optically transparent resin film having a light incident surface and a light exit surface opposite the light incident surface. The transparent substrate may be formed of a single-layer resin film, or may be formed by laminating multiple resin films. The resin may include, but is not limited to, one or more of cellulose ester-based resins such as triacetyl cellulose (TAC), cyclic polyolefin-based resins such as amorphous cyclic polyolefin (COP), 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. For example, by including a polyester-based resin such as polyethylene terephthalate (PET), the transparent substrate may further improve the contrast ratio and brightness.

[0118] In one embodiment, the transparent substrate may have a haze of 30% or less, for example, 2% to 30%, and a light transmittance of 90% or more, for example, 95% to 100%. In this range, the transparent substrate may be applied to a polarizing plate.

[0119] The thickness of the transparent substrate may be 5 μm to 200 μm, for example, 30 μm to 120 μm. In this range, the transparent substrate can be used for a polarizing plate.

[0120] A functional layer may be further laminated on at least one surface of the transparent substrate, which may be a primer layer, an anti-glare layer, an anti-reflection layer, a low refractive index layer, a high refractive index layer, a hard coating layer, an anti-fingerprint layer, etc.

[0121] The protective layer is an isotropic film and may have substantially no retardation, but has a predetermined range of in-plane retardation, and therefore can provide an additional function when combined with a polarizing plate.

[0122] In one specific example, the protective layer may have an in-plane retardation of 3,000 nm or more at a wavelength of 550 nm. This range can promote improvement in the brightness and / or contrast when combined with an optically functional layer. In one specific example, the in-plane retardation may be 4,000 nm or more, 8,000 nm or more, for example, 10,000 nm or more, more than 10,000 nm, 10,100 nm to 30,000 nm, or 10,100 nm to 15,000 nm.

[0123] In another specific example, the protective layer may have an in-plane retardation of less than 3,000 nm at a wavelength of 550 nm. For example, the protective layer may have an in-plane retardation of 0 nm to 1,000 nm, or 10 nm to 500 nm at a wavelength of 550 nm.

[0124] The protective layer may be a first protective layer, a second protective layer, a third protective layer, or the like, as described below.

[0125] (iii) adhesive layer and / or adhesive layer The pressure-sensitive adhesive layer and / or the adhesive layer can adhere or bond a polarizer, an optically functional layer, a protective layer, a functional film, or the like.

[0126] The adhesive layer may be formed of a conventional composition known to those skilled in the art. For example, the adhesive layer may be a (meth)acrylic, epoxy, silicone, urethane, epoxy (meth)acrylic, or urethane (meth)acrylic adhesive layer. For example, the adhesive layer may be a pressure sensitive adhesive (PSA) layer.

[0127] The adhesive layer may be an adhesive layer formed from a conventional composition known to those skilled in the art, such as a water-based adhesive or a photocurable adhesive.

[0128] (iv) Functional films The functional film does not necessarily have to be included in the polarizing plate, but may be a film that provides additional functions when included in the polarizing plate.

[0129] The functional films and functional coating layers may be anti-glare films, anti-reflection films, ultra-low reflection films, low refractive index films, high refractive index films, or anti-fingerprint films.

[0130] 8 to 12 are cross-sectional views of a polarizing plate according to an embodiment of the present invention.

[0131] The polarizing plate can include a polarizer 40 , and a first optical functional layer 10 and a second optical functional layer 20 sequentially stacked on the light exit surface of the polarizer 40 .

[0132] The polarizing plate can include a polarizer 40 , and a first optical functional layer 10 , a second optical functional layer 20 , and a first protective layer 50 that are sequentially stacked on the light exit surface of the polarizer 40 .

[0133] The polarizing plate may include a polarizer 40, a first optical functional layer 10, a second optical functional layer 20, and a functional coating layer 60 which are sequentially stacked on the light exit surface of the polarizer 40.

[0134] The polarizing plate can include a polarizer 40, a second protective layer 70, a first optical functional layer 10, a second optical functional layer 20, and a first protective layer 50 which are sequentially stacked on the light exit surface of the polarizer 40.

[0135] The polarizing plate may include a polarizer 40, a second protective layer 70 stacked in sequence on the light exit surface of the polarizer 40, a first optical functional layer 10, a second optical functional layer 20 and a first protective layer 50, and a third protective layer 80 stacked on the light incident surface of the polarizer 40.

[0136] 8 to 12, the second optical functional layer may further include the above-described acicular particles. In one specific example, the acicular particles are also oriented in the in-plane direction of the second optical functional layer, and the orientation angle and standard deviation of the orientation angle can be adjusted within the range of the average value and standard deviation of the orientation angle of the acicular particles in the first optical functional layer.

[0137] Each layer in the polarizing plate described above may be laminated with an adhesive layer, a sticking layer, or the like, if necessary.

[0138] The optical display device of the present invention includes the polarizing plate of the present invention.

[0139] In one specific example, the optical display device of the present invention can include the polarizing plate of the present invention as a viewer-side polarizing plate for a liquid crystal panel. The "viewer-side polarizing plate" is a polarizing plate that is disposed on the screen side of the liquid crystal panel, i.e., opposite to the light source side.

[0140] In one specific example, the liquid crystal display device includes a condensing backlight unit, a light source-side polarizing plate, a liquid crystal panel, and a viewer-side polarizing plate stacked in this order, and the viewer-side polarizing plate may include the polarizing plate of the present invention. The "light source-side polarizing plate" refers to a polarizing plate disposed on the light source side. The liquid crystal panel may be in a VA (vertical alignment) mode, an IPS mode, a PVA (patterned vertical alignment) mode, or an S-PVA (super-patterned vertical alignment) mode, but is not limited thereto.

[0141] The optical display may be a foldable or flexible optical display or a non-foldable or non-flexible optical display. [Example]

[0142] The present invention will be described in more detail with reference to preferred examples thereof below, but the scope of the present invention is not limited to the following examples.

[0143] Example 1 (1) A mixture of CaCO3 particles (CaCO3: needle-shaped anisotropic microparticles, length: 10 μm to 30 μm, cross-sectional diameter: 0.5 μm to 2.0 μm, Whiscal A, MARUO CALCIMM, refractive index: 1.68) was prepared and added to a methyl ethyl ketone solution containing KBM503 (3-methacryloxypropyltrimethoxysilane). After reacting at room temperature, the mixture was dried in an oven at 90°C to remove the solvent, producing a mixture of CaCO3 needle-shaped particles surface-modified with 3-methacryloxypropyltrimethoxysilane.

[0144] Methyl ethyl ketone and the surface-modified CaCO3 particles were added to an adhesive resin (SAIDEN Co., Ltd.) and dispersed for 4 hours using a homogenizer. Then, 0.2 parts by weight of isophorone diisocyanate was added to 100 parts by weight of the adhesive resin, and the mixture was stirred at 500 rpm for 15 minutes to prepare a composition for the first optical functional layer (viscosity: 1050 cps at 25°C) containing the surface-modified CaCO3 particles.

[0145] (2) A polyvinyl alcohol film was stretched 3 times at 60°C, iodine was adsorbed, and then the film was stretched 2.5 times in a boric acid solution at 40°C to produce a polarizer (thickness: 13 μm, light transmittance: 44%).

[0146] (3) A polyethylene terephthalate (PET) film (DSG-17(Z)PET80, DNP) was attached to the upper surface of the prepared polarizer, and a cyclic olefin polymer (COP) film was attached to the lower surface with an adhesive. The prepared composition for the first optical functional layer was coated on the upper surface of the PET film to a thickness of 20 μm using a coating bar, and thermally cured at 90° C. for 1 hour to form a first optical functional layer (adhesive layer, glass transition temperature of the matrix: −61° C., storage modulus of the matrix: 7×10 -2 The CaCO3 needle-shaped particles in the first optical functional layer were oriented, with an average orientation angle of +1.6° and a standard deviation of 7.2°.

[0147] (4) A composition containing an active energy ray-curable resin (SSC-4540P, Shina T&C) was applied to a predetermined thickness on the lower surface of a PET film (DNP, DSG-17(Z)PET80, in-plane retardation of 8000 nm at a wavelength of 550 nm, with a low-reflection layer on the upper surface), and then photocured to form a second optically functional layer (refractive index: 1.46, thickness: 10 μm).

[0148] (5) The first optical functional layer in (3) and the second optical functional layer in (4) were bonded together to produce a polarizing plate laminated in the following order: PET film - second optical functional layer - first optical functional layer - PET film - polarizer - COP film.

[0149] Example 2 A polarizing plate laminated in the order of PET film-second optical functional layer-first optical functional layer-PET film-polarizer-COP film was prepared in the same manner as in Example 1, except that the particle content and the average value and standard deviation of the orientation angle of the acicular particles were changed by changing the viscosity and application pressure of the composition for the first optical functional layer.

[0150] Example 3 A polarizing plate laminated in the order of PET film-second optical functional layer-first optical functional layer-PET film-polarizer-COP film was prepared in the same manner as in Example 1, except that the particle content and the average value and standard deviation of the orientation angle of the acicular particles were changed by changing the viscosity and application pressure of the composition for the first optical functional layer.

[0151] Comparative Example 1 In Example 1, a polarizing plate having a PET film, a second optical functional layer, a first optical functional layer, a PET film, a polarizer, and a COP film laminated in this order was prepared in the same manner as in Example 1, except that the viscosity and application pressure of the composition for the first optical functional layer were changed to change the average value and standard deviation of the orientation angle of the acicular particles.

[0152] Comparative Example 2 In Example 1, a polarizing plate having a PET film, a second optical functional layer, a first optical functional layer, a PET film, a polarizer, and a COP film laminated in this order was prepared in the same manner as in Example 1, except that the coating pressure of the composition for the first optical functional layer was changed to change the average value and standard deviation of the orientation angle of the acicular particles.

[0153] Comparative Example 3 In Example 1, the second optical functional layer was not formed, so a polarizing plate was produced in which the PET film-first optical functional layer-PET film-polarizer-COP film were laminated in this order.

[0154] Comparative Example 4 A polarizing plate having a PET film, a layer formed of a composition containing a thermosetting resin, a first optical functional layer, a PET film, a polarizer, and a COP film laminated in this order was prepared in the same manner as in Example 1, except that an adhesive resin (thermosetting adhesive resin, manufactured by SAIDEN Co., Ltd.) was used instead of a composition containing an active energy ray curable resin when preparing the second optical functional layer.

[0155] Reference example 1 With reference to Example 1, a polarizing plate was produced in which a PET film, a polarizer, and a COP film were laminated in this order without using the first and second optical functional layers.

[0156] <Measurement of glass transition temperature and storage modulus of matrix> The compositions containing the thermosetting (meth)acrylic adhesive resins used in the examples and comparative examples (except for the surface-modified CaCO3 particles) were cured in the same manner to prepare 15 mg of matrix (on 6 mm Al pan). The matrix was heated to 180°C at a heating rate of 20°C / min in a nitrogen atmosphere (flow rate 50 mL / min), cooled to -100°C, and then heated to 100°C at a heating rate of 10°C / min. The glass transition temperature was measured using a Discovery (TA Instruments) and found to be -61°C.

[0157] The composition containing the thermosetting (meth)acrylic adhesive resin used in the examples and comparative examples (excluding the surface-modified CaCO3 particles) was applied onto a release film and dried at 95°C for 4 minutes. After that, a matrix was formed on the release film to a thickness of 50 μm. The matrix was laminated to a thickness of 500 μm and cut into a circle with a diameter of 8 mm to prepare a test piece. The storage modulus of the test piece was measured at 25°C using a storage modulus measuring device (ARES, Advanced Rheometry Expansion System, TA instrument) while increasing the temperature (10°C / min) in the temperature range of 0°C to 100°C. The storage modulus was 7×10 -2 MPa.

[0158] The following models for measuring the viewing angle were manufactured for the polarizing plates manufactured in the Examples and Comparative Examples, and the physical properties shown in Table 1 below were evaluated.

[0159] A model for measuring a viewing angle was produced by removing the polarizing plate on the viewer's side from a liquid crystal panel model UN55KS8000F (55 inches, Samsung Electronics TV) and bonding the polarizing plates produced in the examples and comparative examples to the polarizing plate on the viewer's side. The polarizing plate on the light source side in the model for measuring a viewing angle was a laminate of a COP film, a polarizer, and a PET film in this order from the liquid crystal panel.

[0160] The following physical properties were evaluated, and the results are shown in Table 1 below.

[0161] (1) Mean and standard deviation of orientation angle: The surface of the optical functional layer manufactured in the examples and comparative examples was focused using an optical microscope (Olympus MX61L, 500x magnification (10x50)), and the image was stored by adjusting the height. The mean and standard deviation of the orientation angle were obtained by running the FIJI program (Method: Fourier Components, N bis: 90°, Histogram start: 0°, Histogram end: 180°).

[0162] (2) Brightness / Darkness Ratio (unit: %): An LED light source, a light guide plate, and the viewing angle measurement model were assembled to manufacture a liquid crystal display device including a one-side edge-type LED light source (the same configuration as a Samsung TV (55-inch, model: UN55KS8000F) except for the configuration of the liquid crystal display module in the Examples and Comparative Examples). The brightness / darkness ratio was measured in a spherical coordinate system at the front (0°, 0°) and side (0°, 60°) angles using an EZCONTRAST X88RC (EZXL-176R-F422A4, ELDIM). The brightness / darkness ratio was calculated as the ratio of brightness in white mode to brightness in black mode. The relative brightness / darkness ratio was calculated as {(brightness / darkness ratios of Examples, Comparative Examples, and Reference Example 1) / (brightness / darkness ratio of Reference Example 1)} × 100.

[0163] (3) Pencil Hardness: The polarizing plates manufactured in the examples and comparative examples were attached to a glass plate, and the outermost surface was evaluated using a pencil hardness tester (Coretec CT-PC2) according to the ASTM D3502 method. When scratched five times with increasing pencil hardness at a load of 200 g and an angle of 45°, if scratches were observed three or more times, it was determined that a scratch had occurred at that pencil hardness. If the initial pencil hardness at which a scratch was observed was 3H, the pencil hardness was 2H. If the initial pencil hardness at which a scratch was observed was 2H, the pencil hardness was H.

[0164] (4) Light transmittance of polarizing plate (unit: %): The polarizing plates manufactured in the examples and comparative examples were evaluated using a spectrometer, which is a light transmittance measuring device.

[0165] [Table 1] *Particle content: The content of needle-shaped particles (CaCO3) in the second optical functional layer

[0166] As shown in Table 1, the polarizing plate of the present invention had excellent visibility improving effect and excellent hardness even without a pattern, for example, a visibility improving pattern. Furthermore, although not shown in Table 1, the polarizing plate of the present invention can reduce curling.

[0167] On the other hand, the polarizing plates of Comparative Examples 1 to 4, which deviate from the configuration of the present invention, could not provide all of the effects of the present invention.

[0168] Simple modifications or variations of the present invention can be easily implemented by those skilled in the art, and all such modifications and variations can be considered to be included within the scope of the present invention.

Claims

1. The polarizer includes a first optical functional layer and a second optical functional layer sequentially stacked on one surface of the polarizer, the first optical functional layer contains anisotropic particles, the anisotropic particles include acicular particles, and the acicular particles are oriented in an in-plane direction of the first optical functional layer; when the light absorption axis of the polarizer is set to 0°, an average value of an orientation angle between the light absorption axis of the polarizer and a length direction of the acicular particles is −10° to +10°, and a standard deviation of the orientation angle is 15° or less; The polarizing plate, wherein the second optical functional layer contains a cured product of a composition containing an active energy ray-curable resin.

2. The polarizing plate according to claim 1 , wherein the first optical functional layer is a contrast or brightness improving layer.

3. The polarizing plate of claim 1 , wherein the upper and lower surfaces of the second optical functional layer are entirely flat.

4. 2. The polarizing plate according to claim 1, wherein the needle-shaped particles are needle-shaped microparticles.

5. 2. The polarizing plate of claim 1, wherein the needle-shaped particles are formed of one or more of titanium oxide, zirconium oxide, zinc oxide, calcium carbonate, boehmite, aluminum borate, calcium silicate, magnesium sulfate, magnesium sulfate hydrate, and potassium titanate.

6. 2. The polarizing plate according to claim 1, wherein the needle-shaped particles have an average aspect ratio of 5 to 60.

7. 2. The polarizing plate according to claim 1, wherein the needle-shaped particles are contained in the first optical functional layer in an amount of 1% by weight to 30% by weight.

8. 2. The polarizing plate according to claim 1, wherein the first optical functional layer comprises a matrix in which the acicular particles are impregnated.

9. 9. The polarizing plate according to claim 8, wherein the matrix is ​​adhesive or non-adhesive.

10. The matrix has a glass transition temperature of −10° C. or lower and a storage modulus of 1×10 at 25° C. －３ MPa to 9×10 －１ The polarizing plate according to claim 8 , wherein the strength is MPa.

11. 2. The polarizing plate according to claim 1, wherein the active energy ray-curable resin contains a resin having a vinyl group or a (meth)acrylate group.

12. 2. The polarizing plate according to claim 1, wherein the refractive index of the matrix in the first optical functional layer minus the refractive index of the second optical functional layer is 0.1 or less.

13. The polarizing plate according to claim 1 , wherein the second optical functional layer is thinner than the first optical functional layer.

14. The polarizing plate according to claim 1 , comprising at least one layer selected from the group consisting of a protective layer, an adhesive layer, a bonding layer, a functional film, and a functional coating layer.

15. The polarizing plate according to claim 14 , wherein the functional film and the functional coating layer are each an anti-glare layer, an anti-reflection layer, an ultra-low reflection layer, a low refractive index layer, a high refractive index layer, or an anti-fingerprint layer.

16. An optical display device comprising the polarizing plate of any one of claims 1 to 15.

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