Polarizing plate and optical display device

Abstract

Provided are a polarizing plate and an optical display device comprising same, the polarizing plate comprising: a polarizer; and an optically functional layer sequentially stacked on one surface of the polarizer, wherein the optically functional layer: includes a matrix and anisotropic particles impregnated into the matrix, the anisotropic particles including acicular particles, and the acicular particles being oriented in the in-plane direction of the optically functional layer; has an average value of orientation angles of the acicular particles of -10° to +10°; and has an anisotropic diffusivity of 1.5 to 2.5.

Description

Polarizing plates and optical display devices

[0001] It relates to polarizing plates and optical display devices.

[0002]

[0003] The liquid crystal display device has a structure in which a polarizing plate on the viewer side, a liquid crystal panel, and a polarizing plate on the light source side are sequentially laminated.

[0004] While liquid crystal displays (LCDs) offer many advantages, improving side visibility and brightness can be desirable. One method for improving visibility and brightness involves adding a visibility-enhancing layer, comprising two resin layers with different refractive indices and a pattern formed at the interface between the resin layers, to the polarizing plate on the viewing side. However, the process of forming the pattern can degrade the yield of the visibility-enhancing layer and limit material cost savings. Therefore, there is a need for a polarizing plate that can improve visibility even without such a visibility-enhancing layer.

[0005] The background technology of the present invention is disclosed in Korean Patent Publication No. 2018-0047569, etc.

[0006]

[0007] For example, a polarizing plate is provided that improves visibility, brightness from the front, and contrast ratio from the side without having a visibility-improving pattern itself or a visibility-improving layer having a pattern.

[0008]

[0009] According to one embodiment, a polarizing plate comprises a polarizer; and an optical functional layer laminated on one surface of the polarizer, wherein the optical functional layer includes a matrix and anisotropic particles impregnated in the matrix, wherein the anisotropic particles include acicular particles, and at least some of the acicular particles are oriented in an in-plane direction of the optical functional layer, wherein the optical functional layer has an average value of an orientation angle of the acicular particles of -10° to +10°, and an anisotropic diffusivity of 1.5 to 2.5.

[0010] According to another embodiment, the optical display device includes the polarizing plate.

[0011]

[0012] The polarizing plate improves visibility, brightness from the front, and contrast ratio from the side even without a pattern, such as a pattern itself for improving visibility or a visibility improving layer having a pattern.

[0013]

[0014] Figure 1 is a conceptual diagram of a needle-shaped particle.

[0015] Figure 2 is a conceptual diagram of an optical functional layer in a polarizing plate.

[0016] Figure 3 is a schematic diagram showing the distribution of angles formed by the long axis of needle-shaped particles with respect to the reference when the light absorption axis of the polarizer is 90° with respect to the reference.

[0017] Figure 4 is a conceptual diagram explaining anisotropic diffusion.

[0018] Figures 5 to 8 are cross-sectional views of a polarizing plate of one embodiment.

[0019] Figure 9 is a schematic diagram for measuring anisotropic diffusion.

[0020]

[0021] With reference to the attached drawings, the present invention is described in detail with respect to embodiments thereof so that those skilled in the art can easily implement the invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0022] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0023] In order to clearly explain the present invention in the drawings, parts unrelated to the description are omitted, and the same or similar components are given the same drawing reference numerals throughout the specification.

[0024] In this specification, "upper" and "lower" are defined based on the drawing, and depending on the perspective, "upper" may be changed to "lower" and "lower" may be changed to "upper", and reference to "on" or "on" may include not only directly above but also cases where another structure is intervening. On the other hand, reference to "directly on", "directly above", "formed directly" or "formed in direct contact with" means that no other structure is intervening.

[0025] In this specification, the “in-plane phase difference (Re)” is a value at a wavelength of 550 nm and is expressed by the following formula A:

[0026] <Formula A>

[0027] Re = (nx - ny) xd

[0028] (In the above formula A, nx and ny are the refractive indices of the protective layer in the slow axis direction and the fast axis direction, respectively, at a wavelength of 550 nm, and d is the thickness of the protective layer (unit: nm).)

[0029] As used herein, “(meth)acrylic” means acrylic and / or methacrylic.

[0030] In this specification, “refractive index” may be a value measured at a wavelength of 380 to 780 nm, specifically 550 nm.

[0031] In this specification, “light transmittance” refers to a characteristic measured by dividing it into total light transmittance, parallel transmittance, and diffuse transmittance at a wavelength of 400 to 700 nm, and may be a value measured in the visible light range with a maximum value at 555 nm.

[0032] When describing a numerical range in this specification, “X to Y” means “X≤ and ≤Y”.

[0033] According to one embodiment, a polarizing plate provides a visibility improvement effect without including a visibility improvement layer comprising resin layers having a pattern or a pattern at an interface. The polarizing plate improves relative luminance at the front and contrast ratio at the side.

[0034] A polarizing plate according to one embodiment comprises a polarizer; and an optical functional layer laminated on one surface of the polarizer, wherein the optical functional layer comprises a matrix and anisotropic particles impregnated in the matrix, wherein the anisotropic particles comprise acicular particles, wherein at least some of the acicular particles are oriented in an in-plane direction of the optical functional layer, wherein the optical functional layer has an average value of an orientation angle of the acicular particles of -10° to +10°, and wherein the optical functional layer has an anisotropic diffusivity of 1.5 to 2.5.

[0035] In one specific example, the optical functional layer may be a contrast ratio improvement layer or a visibility improvement layer.

[0036] Hereinafter, the anisotropic particles are described by referring to them as needle-shaped particles. The anisotropic particles may have other shapes besides the needle-shaped particles. Preferably, the anisotropic particles may be needle-shaped particles.

[0037] In one specific example, the optical functional layer may have at least one of the upper surface and the lower surface as a plane.

[0038] The above needle-shaped particles have a short axis direction and a long axis direction.

[0039] The short-axis and long-axis directions of the above-mentioned needle-shaped particles are described with reference to Fig. 1. Fig. 1 is a conceptual diagram of the needle-shaped particles.

[0040] Referring to Fig. 1, unlike spherical particles, needle-shaped particles may have a relatively long major axis direction (L) and a relatively short minor axis direction (S) compared to the major axis direction.

[0041] According to one embodiment, the major axis direction may be the longitudinal direction of the needle-shaped particle, and the minor axis direction may be the cross-sectional direction of the needle-shaped particle.

[0042] Next, the orientation of the needle-shaped particles within the optical functional layer is described. Fig. 2 is a conceptual diagram of the optical functional layer in a polarizing plate.

[0043] Referring to FIG. 2, the needle-shaped particles 1 may be oriented in one direction within the optical functional layer 10. According to one embodiment, the needle-shaped particles may be oriented in the direction of the long axis of the needle-shaped particles. The needle-shaped particles 1 may be oriented in one direction within the matrix 2 of the optical functional layer 10.

[0044] The average value of the orientation angle of the above-mentioned needle-shaped particles is -10° to +10°.

[0045] The above 'orientation angle' refers to the angle formed by the light absorption axis of the polarizer and the major axis direction of the needle-shaped particle when the light absorption axis of the polarizer is set to 0°. Spherical particles, especially isotropic particles, have a spherical shape, and spherical particles do not have a minor axis direction or major axis direction themselves, so there is no orientation angle.

[0046] When the average value of the orientation angle is between -10° and +10°, light incident from the polarizer is emitted in different directions when passing through the needle-shaped particles, which can facilitate improving the contrast ratio and brightness at the front and side. The light absorption axis of the polarizer can be the MD (machine direction) of the polarizer.

[0047] The average value of the orientation angle is explained with reference to Fig. 3. Fig. 3 is a schematic diagram showing the distribution of the angle formed by the major axis of the needle-shaped particles with respect to the reference, when the optical absorption axis of the polarizer is set at 90° with respect to the reference. Referring to Fig. 3, it can be confirmed that the average value of the orientation angle is -10° to +10°.

[0048] (The average value obtained by averaging the above orientation angles - 90°) is the average value of the above orientation angles. For example, if (the average value obtained by averaging the above orientation angles) is 80°, the average value of the orientation angles is -10°, and if (the average value obtained by averaging the above orientation angles) is 100°, the average value of the orientation angles is +10°. The above orientation angles can be measured by the method described below.

[0049] Preferably, the average value of the orientation angle may be -5.0° to +5.0°, -4.0° to +4.0°, and more preferably -2.5° to +2.5°. In the above range, the effect of the present invention may be further improved.

[0050] In one specific example, the standard deviation of the orientation angle of the needle-shaped particles may be 20° or less. Within this range, it may be easy to improve the brightness at the front and the contrast ratio at the side. Preferably, the standard deviation of the orientation angle may be 0° to 8.5°, more preferably 5° to 8.5°, or 5° to 8°. Within this range, the effect may be further improved.

[0051] The standard deviation of the above orientation angles can be measured by conventional methods known to those skilled in the art.

[0052] In one specific embodiment, the optical functional layer is aligned such that at least 90%, for example, 95% to 100%, of the acicular particles are aligned such that the alignment angle is between -10° and +10°. Within this range, a uniform contrast ratio and improved visibility can be achieved. Here, '%' refers to the ratio of the weight of the acicular particles having an alignment angle between -10° and +10° to the weight of the total acicular particles contained in the optical functional layer.

[0053] The above optical functional layer can further improve the relative brightness at the front and the contrast ratio at the side by having an anisotropic diffusion coefficient of 1.5 to 2.5 while satisfying the average value of the orientation angle of -10° to +10°.

[0054] First, anisotropic diffusion is explained. Figure 4 is a conceptual diagram explaining anisotropic diffusion.

[0055] The above anisotropic diffusivity is a numerical value that evaluates the extent to which incident light from a polarizer or the like is diffused when incident on a needle-shaped particle. The above anisotropic diffusivity can be calculated according to Equation 1 below:

[0056] [Formula 1]

[0057] Anisotropic diffusivity = (Xt / Xi) / (Yt / Yi)

[0058] (In the above equation 1,

[0059] Xt is the optical diffusivity measured in the short axis direction of the needle-shaped particles for the matrix impregnated with needle-shaped particles,

[0060] Yt is the optical diffusivity measured in the longitudinal direction of the needle-shaped particles for the matrix impregnated with needle-shaped particles,

[0061] Xi is the optical diffusivity measured in the same direction as Xt for a matrix not impregnated with needle-shaped particles,

[0062] Yi is the optical diffusivity measured in the same direction as Yt for the matrix not impregnated with needle-shaped particles.

[0063] In Fig. 4, (a) represents the optical diffusion rates Xi and Yi, and (b) represents the optical diffusion rates Xt and Yt.

[0064] As shown in (a), it can be seen that the light diffusivities Xi and Yi measured in the short-axis and long-axis directions, respectively, are substantially the same for the matrix not impregnated with needle-shaped particles assuming that the matrix is ​​impregnated with needle-shaped particles as in (b). In (a), the white marks indicate the degree to which light incident from a point light source is diffused from the position of the point light source when passing through the matrix during the measurement of the light diffusivities, and the black marks indicate the portions through which the light is not transmitted.

[0065] As shown in (b), the matrix impregnated with acicular particles exhibits light diffusivities Xt and Yt measured in the short-axis direction and the long-axis direction of the acicular particles, respectively. In (b), the white marks indicate the degree to which light incident from a point light source is diffused from the position of the point light source when passing through the matrix during the measurement of light diffusivities, and the black marks indicate the portion where the light is not transmitted. Referring to (b), it can be seen that the degree of diffusion is different in the short-axis direction and the long-axis direction of the acicular particles, and that more light is diffused in the short-axis direction than in the long-axis direction.

[0066] The matrix not impregnated with the above-mentioned needle-shaped particles is substantially the same as the matrix impregnated with the above-mentioned needle-shaped particles, except that the needle-shaped particles are not impregnated.

[0067] The above anisotropic diffusivity of 1.5 to 2.5 was specified to evaluate whether the optical functional layer including needle-shaped particles can improve visibility from the side and enhance contrast ratio from the side and front. The optical functional layer is based on the assumption that incident light is diffused in the short axis direction of the needle-shaped particles, and for this purpose, the above anisotropic diffusivity of 1.5 to 2.5 was set.

[0068] If the anisotropic diffusion of the optical functional layer is less than 1.5, the improvement in the side and front contrast ratio is not significant, so the effect of improving the side and front contrast ratio by adding the optical functional layer may not be obtained, and the improvement in the front relative brightness may also be insignificant.

[0069] If the anisotropic diffusion coefficient of the optical functional layer exceeds 2.5, the front relative luminance may be too low to be applied to an optical display device.

[0070] For example, the anisotropic diffusivity may be 1.5 to 2.3, for example 1.5 to 2.1.

[0071] The above anisotropic diffusivity is a value measured for a matrix impregnated with the optical functional layer, preferably needle-shaped particles. The orientation direction of the needle-shaped particles can be distinguished into the major axis direction and the minor axis direction.

[0072] The above anisotropic diffusion coefficient of 1.5 to 2.5 can be easily implemented by satisfying all of the conditions described below among the optical functional layers:

[0073] (i) Average aspect ratio of needle-shaped particles = 5 to 50.

[0074] (ii) Refractive index of the needle-shaped particle in the short axis direction - Refractive index of the matrix = 0.15 to 0.3

[0075] (iii) Content of needle-shaped particles in the optical functional layer = 1 to 10 wt%

[0076] (iv) Ratio of the average surface area in the short axis direction to the average surface area in the long axis direction of the needle-shaped particles = 0.2 to 900

[0077] The above anisotropic diffusion coefficient of 1.5 to 2.5 is designed to provide a matrix including acicular particles satisfying the average value of the orientation angle of the acicular particles and the standard deviation of the orientation angle to provide a further improved relative luminance in the front and contrast ratio in the side.

[0078] The above anisotropic diffusion coefficient of 1.5 to 2.5 can be achieved by satisfying (i) to (iv) above.

[0079] (i) In relation to this, the average aspect ratio of the acicular particles may be an average value of the aspect ratio calculated as the ratio of the maximum length in the major axis direction of the acicular particles to the minimum cross-sectional diameter in the minor axis direction of the acicular particles. When the average aspect ratio is 5 to 50, the optical functional layer can easily reach an anisotropic diffusion degree of 1.5 to 2.5. In addition, when the average aspect ratio is 5 to 50, there may be a light diffusion effect in the minor axis direction of the particles.

[0080] For example, the average aspect ratio of the needle-shaped particles may be 5 to 40, 10 to 35.

[0081] According to one embodiment, the minimum cross-sectional diameter in the short axis direction of the acicular particles may be 0.5 to 4.0 μm, 1.0 to 3.0 μm, and preferably 1.0 to 2.0 μm. In the above range, the aspect ratio may increase, thereby providing a lateral diffusion effect. The 'cross-sectional diameter' refers to the cross-sectional diameter of the acicular particles, and may refer to the maximum value among the diameters measured at the cross section among the acicular particles.

[0082] In one specific example, the cross-section of the needle-shaped particle may be circular, elliptical, or the like.

[0083] According to one embodiment, the maximum length in the longitudinal direction of the needle-shaped particles may be 10 to 45 μm, for example, 10 to 40 μm, 15 to 40 μm. Within this range, the orientation of the needle-shaped particles in the present invention is facilitated, which may help improve the lateral contrast ratio and brightness.

[0084] (ii) In relation to this, the difference between the refractive index of the needle-shaped particle in the short axis direction and the refractive index of the matrix (refractive index of the needle-shaped particle in the short axis direction - refractive index of the matrix) is 0.15 to 0.3.

[0085] The optical functional layer can easily reach the anisotropic diffusion of 1.5 to 2.5 by making the difference between the refractive index of the acicular particles in the short axis direction and the refractive index of the matrix to be 0.15 to 0.3. For example, the refractive index difference can be 0.15 to 0.25.

[0086] In the present invention, the refractive index of the needle-shaped particles in the short axis direction and the refractive index of the matrix are taken into consideration. If the difference between the refractive index of the needle-shaped particles in the long axis direction and the refractive index of the matrix is ​​considered instead of the refractive index of the needle-shaped particles in the short axis direction, there may be a problem in that the diffusion of light in the long axis direction increases as the refractive index difference increases.

[0087] In one specific example, the refractive index in the short axis direction of the needle-shaped particles may be 1.65 to 2.8. Within this range, the anisotropic diffusion of the optical functional layer may easily reach 1.5 to 2.5.

[0088] For example, the refractive index in the axial direction may be 1.65 to 2.0, or 1.65 to 1.9, or 1.65 to 1.7.

[0089] The refractive index in the short-axis direction of the above-mentioned needle-shaped particles may be an average value of the refractive indices in the short-axis direction of the needle-shaped particles included in the above-mentioned matrix.

[0090] The refractive index in the short-axis direction of the above-mentioned needle-shaped particles can be implemented by controlling the material and / or composition of the needle-shaped particles, but can also be implemented by surface modification of the needle-shaped particles.

[0091] According to one embodiment, the needle-shaped particles may be modified with one or more modifying compounds selected from the group consisting of a silane compound, a surfactant, and an oil. Preferably, the needle-shaped particles may be surface-treated with a silane compound having a (meth)acryloyloxy group or a (meth)acrylate group.

[0092] The silane compound having a (meth)acryloyloxy group or a (meth)acrylate group may include at least one of 3-(meth)acryloyloxypropyl methyldimethoxysilane, 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane, 3-(meth)acryloyloxypropyl triethoxysilane, 3-(meth)acryloyloxypropyltrimethoxysilane, preferably 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropyl triethoxysilane.

[0093] The above modification can be performed by mixing the acicular particles or the mixture of the acicular particles with a solution containing the modifying compound, and performing a modification reaction. In one specific example, the refractive index in the short axis direction of the acicular particles can be controlled by controlling the content of the solution containing the modifying compound and the content of the modifying compound in the solution with respect to the acicular particles or the mixture of the acicular particles when modifying the acicular particles. For example, the solution containing the modifying compound can contain the modifying compound in an amount of 50 to 80 wt%, for example, 50 to 60 wt%. The solvent in the solution is not particularly limited, but may be methyl ethyl ketone or the like. The solution containing the modifying compound can be contained in an amount of 50 to 200 wt%, for example, 80 to 150 wt%, with respect to 100 wt% of the acicular particles or the mixture of the acicular particles.

[0094] According to one embodiment, the needle-shaped particles can be surface-modified by hydrolysis and condensation reactions of surface hydroxyl groups.

[0095] The needle-shaped particles prior to the surface modification may have a refractive index of 1.5 to 2.2, preferably 1.6 to 1.8, and more preferably 1.65 to 1.7. Within the above range, the particles may have an appropriate refractive index compared to the resin layer (or matrix) described below, thereby helping to improve contrast ratio and visibility.

[0096] The needle-shaped particles may include organic particles, inorganic particles, organic-inorganic particles, etc. For example, the needle-shaped particles may include 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., MgSO47H2O), potassium titanate (e.g., K2Ti8O 17 ) may be particles formed of one or more of metal compounds such as silica, inorganic particles such as glass, and organic particles such as synthetic resin. Preferably, needle-shaped particles formed of calcium carbonate can easily implement the effects of the present invention and be easily manufactured.

[0097] According to one embodiment, the refractive index in the short-axis direction of the needle-shaped particle may be greater than the refractive index in the long-axis direction of the needle-shaped particle.

[0098] The refractive index of the major axis of the needle-shaped particles may be 1.50 to 1.55. In this range, the light diffusion effect in the minor axis of the needle-shaped particles is greater than that in the major axis, and the anisotropic diffusion of the optical functional layer can easily reach 1.5 to 2.5.

[0099] The refractive index in the longitudinal direction of the needle-shaped particles may be an average value of the refractive indices in the longitudinal direction of the needle-shaped particles included in the matrix.

[0100] The above matrix may have a refractive index of 1.45 to 1.54, for example, 1.47 to 1.53. In this range, condition (ii) can be easily achieved.

[0101] The above matrix may be a cured product of a composition including at least one of a heat-curable resin and an active energy ray-curable resin.

[0102] In one specific example, each of the thermally curable resin and the active energy ray-curable resin may have a weight average molecular weight of 500,000 g / mol or more, for example, 500,000 to 2 million g / mol.

[0103] A thermosetting resin is a resin that is cured by drying and / or heat treatment, and may include 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, a matrix formed from a composition including a thermosetting resin may be an adhesive layer.

[0104] The active energy ray-curable resin is a resin that is cured by ultraviolet rays including UV, 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, etc., 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 among resins such as (meth)acrylate-based resins, urethane (meth)acrylate-based resins, epoxy (meth)acrylate-based resins, and silicone (meth)acrylate-based resins that can achieve the effects of the present invention.

[0105] The above composition may further include an initiator that cures at least one of a thermally curable resin and an active energy ray-curable resin. For example, the initiator may be at least one 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-based initiator, a ketone-based initiator, or a cyclohexyl ketone-based initiator.

[0106] The above composition may include at least one of a thermosetting crosslinking agent and a photocurable crosslinking agent. The thermosetting crosslinking agent may be an isocyanate-based, epoxy-based, amine-based, or other crosslinking agent. The photocurable crosslinking agent may be a multifunctional photocurable monomer having two or more photocurable reactive groups.

[0107] The above composition may contain conventional additives known to those skilled in the art, such as surface conditioners, antistatic agents, dispersants, dyes, pigments, etc.

[0108] The refractive index of the above matrix can be implemented by controlling the type and / or monomer content of the monomers forming the thermally curable resin and the active energy ray curable resin.

[0109] In one specific example, the matrix may comprise a cured product of a composition comprising a copolymer of a monomer mixture comprising a (meth)acrylic monomer having an alkyl group and a (meth)acrylic monomer having a hydroxyl group, and a curing agent. The cured product may be a thermal curable product or a photocurable product.

[0110] The (meth)acrylic monomer having the above alkyl group may include an unsubstituted, linear or branched (meth)acrylic acid ester having an alkyl group having 1 to 10 carbon atoms. For example, the ester may include at least one of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, iso-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, iso-octyl (meth)acrylate, nonyl (meth)acrylate, and decyl (meth)acrylate, but is not limited thereto. These may be included alone or in a mixture of two or more.

[0111] The (meth)acrylic monomer having a hydroxyl group may include one or more hydroxyl group-containing (meth)acrylates. For example, the hydroxyl group-containing (meth)acrylate may include a C2-C10 alkyl group-containing (meth)acrylate having one or more hydroxyl groups. Specifically, the hydroxyl group-containing (meth)acrylate may include one or more of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate. Preferably, the hydroxyl group-containing (meth)acrylate may include at least one of 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 3-hydroxypropyl (meth)acrylate.

[0112] In the monomer mixture, the (meth)acrylic monomer having the alkyl group may be included in an amount of 50 to 95 wt%, for example, 55 to 95 wt%, 60 to 95 wt%, or 70 to 95 wt%. In the monomer mixture, the (meth)acrylic monomer having the hydroxyl group may be included in an amount of 5 to 50 wt%, for example, 5 to 40 wt%, or 5 to 30 wt%.

[0113] For example, the monomer mixture may include 10 to 80 wt% of n-butyl (meth)acrylate, 10 to 60 wt% of methyl (meth)acrylate, and 5 to 30 wt% of 4-hydroxybutyl (meth)acrylate. Within this range, the matrix can be easily manufactured and the orientation of the anisotropic diffusion particles can also be facilitated.

[0114] The above monomer mixture may further include a (meth)acrylic monomer having an aromatic group. The (meth)acrylic monomer having an aromatic group may facilitate increasing the refractive index of the matrix.

[0115] The (meth)acrylic monomer having an aromatic group may include one or more types of (meth)acrylic monomers having a substituted or unsubstituted aromatic group. For example, the (meth)acrylic monomer having an aromatic group may include, but is not limited to, a compound represented by the following chemical formula 1:

[0116] [Chemical Formula 1]

[0117] CH2=C(R 1 )-C(=O)-OR 2 -Ar

[0118] (In the above chemical formula 1,

[0119] R 1 is a hydrogen or methyl group,

[0120] R 2 is a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms or a substituted or unsubstituted alkylene oxide group having 1 to 20 carbon atoms,

[0121] Ar is a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0122] For example, the (meth)acrylic monomer having the aromatic group may include one or two or more of phenoxybenzyl (meth)acrylate, phenylphenoxyethyl (meth)acrylate, 2-hydroxy-3-phenoxy propyl (meth)acrylate, ethoxylated phenylphenoxy (meth)acrylate, benzyl (meth)acrylate, and biphenylmethyl (meth)acrylate.

[0123] The (meth)acrylic monomer having the above aromatic group may be included in the monomer mixture at 10 to 45 wt%, for example, 20 to 45 wt%. Within the above range, it is easy to provide a matrix with a high refractive index and may not affect other physical properties of the matrix.

[0124] For example, the monomer mixture may include 25 to 55 wt% of N-butyl (meth)acrylate, 10 to 40 wt% of 2-ethylhexyl (meth)acrylate, 5 to 40 wt% of 4-hydroxybutyl (meth)acrylate, and 20 to 45 wt% of biphenylmethyl (meth)acrylate. In the above range, the production of a high refractive index matrix can be facilitated, and the orientation of anisotropic diffusion particles can also be facilitated.

[0125] The curing agent may include a conventional curing agent known to those skilled in the art to heat cure the copolymer. For example, the curing agent may include one or more types of curing agents selected from the group consisting of isocyanate, epoxy, aziridine, and amine. Any suitable curing agent known to those skilled in the art may be selected and used.

[0126] The above curing agent may be included in an amount of 0.1 to 10 parts by weight, for example, 1 to 5 parts by weight, based on 100 parts by weight of the copolymer. Within this range, the copolymer can be sufficiently cured.

[0127] (iii) In relation to this, the needle-shaped particles are included in the optical functional layer in an amount of 1 wt% to 10 wt%. Within this range, the anisotropic diffusion can be easily achieved. For example, the needle-shaped particles can be included in an amount of 3 wt% to 8 wt%. Within this range, the anisotropic diffusion can easily reach 1.5 to 2.5, and there can be an effect of improving the lateral card ratio.

[0128] (iv) In relation to this, the ratio of the average surface area in the short axis direction to the average surface area in the long axis direction of the acicular particles is 0.2 to 900. The ratio can be a standard for determining the degree of light diffused in the short axis direction and the long axis direction when light incident from a polarizer is incident on the acicular particles. In the above range, the anisotropic diffusion of the optical functional layer described above can be easily achieved. For example, the ratio can be 0.5 to 150, 5 to 100.

[0129] The above ratio can be implemented by adjusting the average value of the surface area in the short-axis direction and the average value of the surface area in the long-axis direction of the needle-shaped particles.

[0130] According to one embodiment, the average surface area of ​​the needle-shaped particles in the short axis direction is 5 to 180 ㎛. 2 , for example, 10 to 120 ㎛ 2 , 15 to 80 ㎛ 2 This could be it.

[0131] According to one embodiment, the average value of the surface area in the longitudinal direction of the needle-shaped particles is 0.2 to 15 ㎛ 2 , for example, 0.5 to 8 ㎛ 2 , 0.5 to 4 ㎛ 2 This could be it.

[0132] The optical functional layer can be manufactured by applying the optical functional layer composition to an adherend and then curing it. At this time, the average value of the orientation angle and the standard deviation of the orientation angle can be implemented by adjusting the viscosity of the optical functional layer composition. The average value of the orientation angle and the standard deviation of the orientation angle can also be implemented by adjusting the application pressure, etc., when applying the composition.

[0133] The optical functional layer, for example, the matrix, may have a thickness of 5 to 50 μm, preferably 10 to 40 μm, and more preferably 10 to 30 μm.

[0134] Below, the polarizing plate is explained.

[0135] The polarizing plate has a polarizer and an optical functional layer.

[0136] The polarizing plate may have a light transmittance of 95% or more, for example, 96 to 100%. Within the above range, it may be used as a viewing-side polarizing plate.

[0137] The optical functional layer is laminated on the light-emitting surface of the polarizer. The above-mentioned 'light-emitting surface' is the surface through which the internal light of the backlight unit reaches the polarizer and is emitted from the polarizer.

[0138] The optical functional layer may be an adhesive layer so that it can be directly laminated to the protective layer or polarizer described below without an interlayer adhesive.

[0139] The optical functional layer can be manufactured by applying a composition for an optical functional layer to an adherend and then curing it.

[0140] In addition to the optical functional layer, the polarizing plate may further include one or more polarizers, a protective layer (including a phase difference layer), an adhesive layer, and / or an adhesive layer, a functional film (including a functional coating layer), etc.

[0141] (i) Polarizer

[0142] A polarizer is a linear light absorption polarizer that can provide a polarization function by transmitting only light in one direction among the incident light and absorbing light in a direction perpendicular to the one direction.

[0143] The polarizer may be a polarizer manufactured by dyeing and stretching a polyvinyl alcohol (PVA) film, or a polyene polarizer manufactured by dehydrating a polyvinyl alcohol film.

[0144] The polarizer may have a thickness of 50 μm or less, for example, 5 μm to 30 μm. Within this range, melting and breakage of the film may be avoided during film stretching.

[0145] (ii) protective layer

[0146] A protective layer may be included in a polarizing plate to protect the polarizer or increase the mechanical strength of the polarizing plate. The protective layer may also be an adherend forming an optically functional layer.

[0147] The protective layer may be included in one or more layers at any position of the polarizing plate.

[0148] The protective layer may include a transparent substrate. The transparent substrate may have a higher or lower refractive index than the optically functional layer. Preferably, the transparent substrate has a higher refractive index than the optically functional layer. This can help improve contrast ratio and brightness.

[0149] 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 of resin film, but may also be formed by laminating a plurality of resin films. The resin may include at least one of a cellulose ester resin including triacetyl cellulose (TAC) or the like, a cyclic polyolefin resin including amorphous cyclic polyolefin (COP) or the like, a polycarbonate resin, a polyester resin including polyethylene terephthalate (PET) or the like, a polyethersulfone resin, a polysulfone resin, a polyamide resin, a polyimide resin, an acyclic-polyolefin resin, a polyacrylate resin including polymethyl methacrylate resin, a polyvinyl alcohol resin, a polyvinyl chloride resin, and a polyvinylidene chloride resin, but is not limited thereto. Preferably, the transparent substrate includes a polyester resin including polyethylene terephthalate (PET), etc., thereby further enhancing the contrast ratio and brightness improvement effect.

[0150] The transparent substrate may have a haze of 30% or less, specifically 2% to 30%, and a light transmittance of 90% or more, specifically 95% to 100%. Within the above range, the transparent substrate may be applied to a polarizing plate.

[0151] The thickness of the transparent substrate may be 5 μm to 200 μm, for example, 30 μm to 120 μm. Within the above range, it can be used in a polarizing plate.

[0152] A functional layer may be further laminated on at least one side of the transparent substrate. The functional layer 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.

[0153] The protective layer may be an isotropic film with virtually no phase difference, but may have a certain range of in-plane directional phase difference, which may provide additional functionality when combined with a polarizing plate.

[0154] In one specific embodiment, the protective layer may have an in-plane retardation of 3,000 nm or more at a wavelength of 550 nm. In this range, when combined with an optical functional layer, it may help improve contrast ratio and / or brightness. Preferably, the in-plane retardation may be 4,000 nm or more, 8,000 nm or more, specifically 10,000 nm or more, more specifically greater than 10,000 nm, and more specifically 10,100 nm to 30,000 nm, or 10,100 nm to 15,000 nm.

[0155] In other embodiments, 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.

[0156] The protective layer may be a first protective layer, a second protective layer, or a third protective layer, as described below.

[0157] (iii) adhesive layer and / or adhesive layer;

[0158] The adhesive layer and / or bonding layer can bond or adhere a polarizer, an optical functional layer, a protective layer, a functional film, etc.

[0159] 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.

[0160] The adhesive layer may be formed of a conventional composition known to those skilled in the art. For example, the adhesive layer may be formed of a water-based adhesive, a photocurable adhesive, or the like.

[0161] (iv) Functional film

[0162] A functional film is not necessarily included in a polarizing plate, but may be a film that provides additional functions when included in a polarizing plate.

[0163] The functional film or functional coating layer may be an anti-glare film, an anti-reflection film, an ultra-low-reflection film, a low-refractive index film, a high-refractive index film, or an anti-fingerprint film.

[0164] Figures 5 to 8 are cross-sectional views of a polarizing plate of one embodiment.

[0165] The polarizing plate may include a polarizer (30); and an optical functional layer (10) and a first protective layer (20) laminated on the light-emitting surface of the polarizer (30).

[0166] The polarizing plate may include a polarizer (30); an optical functional layer (10), a first protective layer (20), and a functional coating layer (40) sequentially laminated on the light-emitting surface of the polarizer (30).

[0167] The polarizing plate may include a polarizer (30); an optical functional layer (10), a first protective layer (20), and a functional coating layer (40) sequentially laminated on the light-emitting surface of the polarizer (30).

[0168] The polarizing plate may include a polarizer (30); a second protective layer (50), an optical functional layer (10), a first protective layer (20), and a functional coating layer (40) sequentially laminated on the light-emitting surface of the polarizer (30).

[0169] A polarizing plate may include a polarizer (30); an optical functional layer (10), a first protective layer (20), and a functional coating layer (40) sequentially laminated on the light-emitting surface of the polarizer (30); and a third protective layer (70) sequentially laminated on the light-incident surface of the polarizer (30). A second protective layer (50) may further be laminated between the polarizer (30) and the optical functional layer (10).

[0170] Each layer of the above-described polarizing plate can be laminated by an adhesive layer, an adhesive layer, etc., if necessary.

[0171] The optical display device of the present invention includes the polarizing plate of the present invention.

[0172] In one specific example, the optical display device of the present invention may 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 positioned opposite the screen side, i.e., the light source side, of the liquid crystal panel.

[0173] In one specific example, the liquid crystal display device may sequentially stack a light-collecting backlight unit, a light source-side polarizing plate, a liquid crystal panel, and a viewer-side polarizing plate, wherein the viewer-side polarizing plate may include the polarizing plate of the present invention. The "light source-side polarizing plate" is a polarizing plate disposed on the light source side. The liquid crystal panel may adopt, but is not limited to, a VA (vertical alignment) mode, an IPS mode, a PVA (patterned vertical alignment) mode, or an S-PVA (super-patterned vertical alignment) mode.

[0174] The optical display device may be a foldable or flexible optical display device or a non-foldable or non-flexible optical display device.

[0175]

[0176] Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, the following examples are intended to aid understanding of the present invention, and the scope of the present invention is not limited to the following examples.

[0177]

[0178] Example 1

[0179] (1) 100 parts by weight of a mixture of CaCO3 particles (CaCO3: needle-shaped anisotropic microparticles, length: 10 to 30 μm, cross-sectional diameter: 0.5 to 2.0 μm, Whiscal A, MARUO CALCIUM, refractive index: 1.68) was prepared, added to a methyl ethyl ketone solution containing KBM503 (3-methacryloxypropyl trimethoxysilane), reacted at room temperature, and then dried in an oven at 90°C to remove the solvent, thereby preparing a mixture of CaCO3 needle-shaped particles surface-modified with 3-methacryloxypropyl trimethoxysilane. At this time, the methyl ethyl ketone solution containing KBM503 is added in an amount of 100 parts by weight per 100 parts by weight of the mixture of CaCO3 particles, and KBM-503 is included in an amount of 50 parts by weight in the methyl ethyl ketone solution.

[0180] (2) A monomer mixture and a solvent were charged in a 1:1 weight ratio into a 1 L reactor equipped with a cooling device to reflux nitrogen gas and facilitate temperature control, to prepare a solids content of 50 wt%. Ethyl acetate was used as the solvent. The monomer mixture included 60 parts by weight of n-butyl acrylate, 30 parts by weight of methyl acrylate, and 30 parts by weight of 4-hydroxybutyl acrylate. To remove oxygen from the monomer mixture, nitrogen gas was introduced for 1 hour to replace the reactor, and the internal temperature of the reactor was maintained at 70°C. After uniformly stirring the monomer mixture, 0.05 parts by weight of azobisisobutyronitrile (AIBN) as an initiator was added and reacted for 12 hours to prepare a solution containing an acrylic resin having a weight average molecular weight of 700,000 g / mol, and additional ethyl acetate was added to prepare a solids content of 25 wt%.

[0181] (3) To 100 parts by weight of the acrylic resin manufactured above, 7 parts by weight of the surface-modified CaCO3 particles and 2 parts by weight of a hexamethylene diisocyanate-based curing agent (CK-164, NCI) were added to manufacture a composition for an optical functional layer.

[0182] (4) A polyvinyl alcohol film was stretched 3 times in the MD (machine direction) axis at 60°C, iodine was adsorbed, and then stretched 2.5 times in the MD axis in a boric acid aqueous solution at 40°C to manufacture a polarizer (thickness: 13 μm, light transmittance: 44%).

[0183] (5) A polyethylene terephthalate (PET) film (TA053 Toyobo) was bonded to the upper surface of the manufactured polarizer, and a cyclic olefin polymer (COP) film was bonded to the lower surface using adhesive to manufacture a polarizing film.

[0184] (6) The composition for the optical functional layer manufactured above was coated on the lower surface of a surface-treated PET film (DSG-17(Z)PET80, DNP) with a thickness of 20 μm using a coating bar, dried and heat-cured at 80°C for 2 minutes, and aged at room temperature for 1 day to form an optical functional layer (thickness of 25 μm), and laminated to the polarizing film manufactured in (5) to manufacture a polarizing plate.

[0185] Among the optical functional layers, the matrix has a refractive index of 1.47. The surface-modified CaCO3 particles have a refractive index in the short axis direction of 1.68, a refractive index in the long axis direction of 1.53, and the content of the surface-modified CaCO3 particles in the optical functional layer is approximately 6.4 wt%.

[0186] The average surface area of ​​the long axis of the surface-modified CaCO3 particles is 1.77㎛. 2 And the average value of the surface area in the short axis direction is 33.75㎛ 2 , and the ratio between them is 19.1. The average surface area in the short axis direction and the average surface area in the long axis direction were measured in the long axis and short axis directions using SEM, respectively, and the surface area was calculated.

[0187] Example 2

[0188] An optical functional layer and a polarizing plate were manufactured in the same manner as in Example 1, except that a monomer mixture of 40 parts by weight of n-butyl acrylate, 20 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of 4-hydroxybutyl acrylate, and 30 parts by weight of biphenylmethyl acrylate was used.

[0189] Among the optical functional layers, the matrix has a refractive index of 1.51. The refractive index of the surface-modified CaCO3 particles in the short axis direction is 1.68, and the refractive index in the long axis direction is 1.53.

[0190] Example 3

[0191] In Example 1, an optical functional layer and a polarizing plate were manufactured in the same manner as in Example 1, except that particles having a length of 15 to 25 μm were used through classification of a mixture of CaCO3 particles (CaCO3: needle-shaped anisotropic microparticles, length: 10 to 30 μm, cross-sectional diameter: 0.5 to 2.0 μm, Whiscal A, MARUO CALCIUM Co., Ltd., refractive index: 1.68). Compared to Example 1, the average aspect ratio of the anisotropic particles in the optical functional layer was improved to 20±5, improving uniformity.

[0192] Comparative Example 1

[0193] An optical functional layer and a polarizing plate were manufactured in the same manner as in Example 1, except that 3 parts by weight of potassium titanate particles (Otsuka Chemical Co., TISMP N, refractive index 2.68, diameter 0.5 μm, length 10-20 μm) and 2 parts by weight of a hexamethylene diisocyanate curing agent (CK-164, NCI Co.) were added to 100 parts by weight of the acrylic resin manufactured in Example 1 to manufacture a composition for an optical functional layer. The matrix of the optical functional layer has a refractive index of 1.47. The refractive index of potassium titanate in the uniaxial direction is 2.68.

[0194] Comparative Example 2

[0195] An optical functional layer and a polarizing plate were manufactured in the same manner as in Example 1, except that 7 parts by weight of cubic calcium carbonate particles (CaCO3: cubic anisotropic microparticles, length: 1 to 3.0 ㎛, cross-sectional diameter: 0.5 to 2.0 ㎛, MX-14, MARUO CALCIUM Co., refractive index: 1.68) and 2 parts by weight of a hexamethylene diisocyanate-based curing agent (CK-164, NCI Co.) were added to 100 parts by weight of the acrylic resin manufactured in Example 1 to manufacture a composition for an optical functional layer. The matrix of the optical functional layer has a refractive index of 1.47. The uniaxial refractive index of calcium carbonate is 1.68.

[0196] Comparative Example 3

[0197] An optical functional layer and a polarizing plate were manufactured in the same manner as in Example 1, except that a monomer mixture of 70 parts by weight of biphenylmethyl acrylate, 15 parts by weight of phenoxybenzyl acrylate, and 15 parts by weight of 4-hydroxybutyl acrylate was used. The matrix of the optical functional layer has a refractive index of 1.6. The refractive index of the surface-modified CaCO3 particles in the short-axis direction is 1.68, and the refractive index in the long-axis direction is 1.53.

[0198] Comparative Example 4

[0199] A polarizing plate was manufactured in the same manner as in Example 2, except that the particle content was changed to 12 parts by weight per 100 parts by weight of acrylic resin. The content of surface-modified CaCO3 particles in the optical functional layer was approximately 10.5% by weight.

[0200] Comparative Example 5

[0201] A polarizing plate was manufactured in the same manner as in Example 2, except that the orientation angle of the anisotropic particles was changed by changing the viscosity of the composition by adding a solvent to the composition for the optical functional layer in Example 2.

[0202] Reference example

[0203] A polarizing plate was manufactured in the same manner as in Example 1, except that a polyethylene terephthalate (PET) film (DSG-17(Z)PET80, DNP) was bonded to the upper surface of the polarizer without the optical functional layer, and a cyclic olefin polymer (COP) film was bonded to the lower surface using adhesive.

[0204]

[0205] The manufactured polarizing plate was evaluated as follows, and the results are shown in Table 1.

[0206] Refractive index along the short axis and long axis of the particle:

[0207] The refractive indices in the short axis direction and the long axis direction of the particle were obtained as average values.

[0208] Average aspect ratio of particles:

[0209] The aspect ratio for the particles was calculated as an average value.

[0210] The ratio of the average surface area in the short axis direction to the average surface area in the long axis direction of the particle

[0211] The surface area was calculated by measuring the average surface area of ​​the particle in the long-axis direction and the average surface area of ​​the particle in the short-axis direction using SEM.

[0212] Mean (unit: °) and standard deviation (unit: °) of the orientation angle of the anisotropic particles:

[0213] The surface of the optical functional layer manufactured in the examples and comparative examples was focused on the surface of the optical functional layer with an optical microscope (Olympus MX61L, 500x magnification (10x50)), the height was adjusted, the image was saved, and the FIJI program (Method: Fourier Components, N bis: 90°, Histogram start: 0°, Histogram end: 180° input) was used to obtain the average value of the orientation angle and the standard deviation of the orientation angle.

[0214] Anisotropic diffusion of optical functional layer:

[0215] Anisotropic diffusivities were measured in the major and minor axes of the needle-shaped particles for the optically functional layer. Specifically, the anisotropic diffusivities were measured using a diffusivity measuring device from DeWorld.

[0216] Fig. 9 is a conceptual diagram for measuring anisotropic diffusion. Referring to Fig. 9, an LED point light source 100, a sample holder 200, and an area camera 300 are sequentially positioned on top, an optical functional layer 210 is positioned on the sample holder 200, and light from the point light source 100 passes through the optical functional layer 210 and is diffused, and the diffused area can be measured by the area camera 300. The area camera 300 has a lens with a diameter of 50 mm and a specification of 5 Mpixel.

[0217] Relative luminance (in %) and relative contrast (in %):

[0218] A liquid crystal display (Samsung TV (55 inches, model name: KQ55QNA90AFXKR) including a single-sided edge-type LED light source was manufactured by assembling an LED light source, a light guide plate, and a model for measuring the viewing angle (except for the configuration of the liquid crystal display module of the exemplary and comparative examples) . The contrast ratio was measured in a spherical coordinate system at the front (0°, 0°) and the side (0°, 60°). The contrast ratio is calculated as the ratio of the luminance in the white mode to the luminance in the black mode. The relative luminance value and the relative contrast ratio were calculated using the luminance value and contrast ratio measured in the reference example. The relative luminance value must be 85% or more, and the relative contrast ratio must be 130% or more to be effective in improving screen quality.

[0219] Comparative Example Reference Example 12312345 Particle content (content relative to resin) 777377127 - Matrix refractive index 1.471.511.471.471.471.61.511.51 - Refractive index in particle short axis direction 1.681.681.682.681.681.681.681.68 - Refractive index in long axis direction 1.531.531.532.321.531.531.531.53 - Average aspect ratio 20±1520±1520±520±151.5±0.420±1520±1520±15 - Surface area in long axis direction 1.771.771.770.200.791.771.771.77 - Short axis direction Surface area33.7533.7533.757.51.533.7533.7533.75-Ratio of the average surface area in the short axis direction to the average surface area in the long axis direction19.119.119.138.21.919.119.119.1-Difference in refractive index (short axis)0.210.170.211.210.210.080.170.17-Orientation angle of anisotropic particles-5 to 5-5 to 5-5 to 5-5 to 5-90 to 90-5 to 5-5 to 515-Standard deviation of orientation angle7.36.65.86.929.917.57.814.5-Anisotropy Diffusivity 2.05 1.5 21.45 1.01 1.03 31.5 - Front luminance measurement 748 774.47 56.85 0668 1.886 2.46 60 774.488 Relative luminance 85% 88% 86% 58% 77% 98% 75% 88% 100% Side contrast ratio measurement 515.24 93.125 22.56 38 2.230 33 79.04 5 59.36 44 1.6368 Relative contrast ratio 140% 134% 142% 141% 83% 103% 152% 120% 100%

[0220] As shown in Table 1 above, the polarizing plate of the present invention provides the effect of uniform visibility and screen quality between the front and side through improvement in lateral brightness and contrast ratio without having a pattern.

[0221]

[0222] Simple modifications or changes of the present invention can be easily implemented by a person having ordinary skill in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims

1. A polarizer; and an optical functional layer sequentially laminated on one surface of the polarizer, The optical functional layer comprises a matrix and anisotropic particles impregnated in the matrix, the anisotropic particles comprise needle-shaped particles, and the needle-shaped particles are oriented in the in-plane direction of the optical functional layer. A polarizing plate, wherein the optical functional layer has an average value of the orientation angle of the needle-shaped particles of -10° to +10°, and the optical functional layer has an anisotropic diffusion coefficient of 1.5 to 2.

5.

2. In the first paragraph, the optical functional layer satisfies the following (i) to (iv): (i) Average aspect ratio of needle-shaped particles = 5 to 50; (ii) Refractive index of the needle-shaped particle in the short axis direction - Refractive index of the matrix = 0.15 to 0.3; (iii) Content of needle-shaped particles in the optical functional layer = 1 to 10 wt%; and (iv) The ratio of the average surface area in the short axis direction to the average surface area in the long axis direction of the needle-shaped particles = 0.2 to 900.

3. A polarizing plate in the first paragraph, wherein the refractive index in the short axis direction of the needle-shaped particles is 1.65 to 2.8, and the refractive index in the long axis direction of the needle-shaped particles is 1.50 to 1.

55.

4. A polarizing plate according to claim 1, wherein the needle-shaped particles are surface-treated with a silane compound having a (meth)acryloyloxy group or a (meth)acrylate group.

5. A polarizing plate according to claim 1, wherein the refractive index of the matrix is ​​1.45 to 1.

54.

6. A polarizing plate according to claim 1, wherein the needle-shaped particles are particles comprising at least one of titanium oxide, zirconium oxide, zinc oxide, calcium carbonate, boehmite, aluminum borate, calcium silicate, magnesium sulfate, magnesium sulfate hydrate, potassium titanate, glass particles, and synthetic resin particles.

7. A polarizing plate in the first paragraph, wherein the standard deviation of the orientation angle of the needle-shaped particles is 20° or less.

8. A polarizing plate in accordance with paragraph 1, wherein the optical functional layer is a visibility improvement layer.

9. In the first paragraph, the polarizing plate further includes a protective layer.

10. An optical display device comprising a polarizing plate according to any one of claims 1 to 9.

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