Polarizing plate and optical display apparatus

Abstract

Provided are a polarizing plate and an optical display apparatus comprising same, the polarizing plate comprising: a polarizer; and an optical functional layer laminated on one surface of the polarizer, wherein the optical functional layer includes a matrix and a plurality of microstructures dispersed in the matrix, at least some of the plurality of microstructures include a first resin and needle-shaped particles aligned in one direction in the first resin, the matrix includes a second resin, the first resin includes an alloy-based resin, and the difference in glass transition temperature between the second resin and the alloy-based resin is 10°C or less.

Description

Polarizing plates and optical display devices

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

[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] Liquid crystal displays (LCDs) offer many advantages, but they suffer from low side visibility and low brightness. To address these issues, a method has been proposed: 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, this visibility-enhancing layer suffers from yield degradation and material cost savings due to the pattern-forming process. Therefore, a polarizing plate that can improve visibility without this visibility-enhancing layer is desired.

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

[0006]

[0007] According to one embodiment, a polarizing plate having a visibility improvement effect is provided without having a pattern, for example, a visibility improvement pattern itself or a visibility improvement layer having a pattern.

[0008] According to another embodiment, a polarizing plate is provided in which both frontal luminance and anisotropic diffusion are improved.

[0009] Another embodiment provides a polarizing plate that provides excellent contrast ratio effects even from the front and side.

[0010]

[0011] 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 a plurality of microstructures dispersed in the matrix, wherein at least some of the plurality of microstructures comprise a first resin and needle-shaped particles oriented in one direction within the first resin, wherein the matrix comprises a second resin, wherein the first resin comprises an alloy-based resin, and wherein a difference in glass transition temperature between the second resin and the alloy-based resin is 10°C or less.

[0012] According to another embodiment, the optical display device includes a polarizing plate according to one embodiment.

[0013]

[0014] According to one embodiment, a polarizing plate having a visibility improvement effect is provided without having a pattern, for example, a pattern itself for improving visibility or a visibility improvement layer having a pattern.

[0015] According to another embodiment, a polarizing plate with improved frontal luminance and anisotropic diffusion properties is provided.

[0016] According to another embodiment, a polarizing plate is provided that provides an excellent contrast ratio effect even from the front and side.

[0017]

[0018] Figure 1 is a conceptual diagram of a polarizing plate according to an embodiment.

[0019] Figure 2 is a schematic cross-sectional view of a needle-shaped particle.

[0020] Figure 3 is a cross-sectional view of an optical functional layer in the direction of the light absorption axis of a polarizer in a polarizing plate according to one embodiment.

[0021] Figure 4 is an enlarged cross-sectional view of Figure 3.

[0022] Fig. 5 is a cross-sectional view of an optical functional layer in the direction of the light transmission axis of a polarizer in a polarizing plate according to one embodiment.

[0023] Figure 6 is an enlarged cross-sectional view of Figure 5.

[0024]

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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", or "formed directly" or "formed in direct contact with" means that no other structure is intervening.

[0029] 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:

[0030] <Formula A>

[0031] Re = (nx - ny) xd

[0032] (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).)

[0033] As used herein, “(meth)acrylic” means acrylic and / or methacrylic.

[0034] In this specification, “refractive index” may be a value measured at a wavelength of 380 to 780 nm, specifically 550 nm.

[0035] In this specification, “light transmittance” may be a value measured at a wavelength of 380 to 780 nm, specifically 550 nm.

[0036] When describing a numerical range in this specification, “X to Y” means “X≤ and ≤Y”.

[0037] The polarizing plate of the present invention provides a visibility improvement effect even without a visibility improvement layer comprising resin layers having a pattern or a pattern at the interface. The polarizing plate of the present invention provides a polarizing plate with excellent frontal luminance and anisotropic diffusion properties.

[0038] Here, "anisotropic diffusivity" refers to the ratio of the luminance measured at the side (60°, 0°) to the luminance measured at the front (0°, 0°) and the side (60°, 0°) when a polarizing plate is mounted on an optical display device and luminance is measured in white mode at the front (0°, 0°). The higher this ratio, the higher the anisotropic diffusivity, and the higher the anisotropic diffusivity, the better the effect of improving the contrast ratio and visibility at the side.

[0039] In the present invention, in order to offset the existing reflective polarization characteristics and maximize the asymmetric diffusion function, a suitable resin material was selected for the matrix and microstructure, and acicular particles were oriented within the microstructure. By forming a flow path by the encapsulation function, the acicular particles are oriented in one direction during the unstretched film manufacturing process and the stretching process, thereby providing an optical functional layer having a composite function of visibility enhancement in which the asymmetric diffusion function is integrated within the optical functional layer. The optical functional layer can be combined with a polarizer to ultimately produce a polarizing plate with maximized side viewing angles of a display product.

[0040] A polarizing plate of 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 a plurality of microstructures dispersed in the matrix, wherein at least some of the plurality of microstructures comprise a first resin and needle-shaped particles oriented in one direction within the first resin, wherein the matrix comprises a second resin, wherein the first resin comprises an alloy-based resin, and wherein the second resin and the alloy-based resin have a glass transition temperature difference of 10°C or less.

[0041] The first resin includes an alloy resin, and the difference in glass transition temperature between the alloy resin and the second resin is 10°C or less. Through this, the first resin and the second resin can be used to manufacture the optical functional layer under the same extrusion conditions.

[0042] That is, the optical functional layer can be manufactured by melt-extruding or solution-casting the composition for the optical functional layer to produce an unstretched film and then stretching it. At this time, the difference in glass transition temperatures is 10°C or less, so that the unstretched film can be manufactured under the same conditions, and when the unstretched film is stretched, the difference in viscosity between the first resin and the second resin allows a microstructure to be well formed, and can serve as a kind of channel for the acicular particles in the microstructure to be oriented in one direction. If the difference in glass transition temperatures exceeds 10°C, the orientation of the acicular particles in the microstructure may not be well performed in the manufacturing process and stretching process of the unstretched film.

[0043] Here, 'alloy resin' can mean a resin in which two different resins are non-chemically bonded by complementary forces, or a resin in which one resin is bonded to another resin through a chemical reaction.

[0044] According to one embodiment, the difference in glass transition temperature between the alloy resin and the second resin may be 0°C to 10°C, for example, 0°C to 5°C.

[0045] According to one embodiment, the glass transition temperature of the alloy resin may be equal to or greater than the glass transition temperature of the second resin.

[0046] According to one embodiment, the first resin includes an alloy resin. Compared to an optical functional layer manufactured by manufacturing a conventional resin, which is not an alloy resin, the alloy resin can provide a good refractive index matching between the first resin and the second resin and enhance compatibility with the second resin, polyethylene naphthalate (PEN) resin, thereby providing an excellent appearance of the final optical functional layer and an excellent side visibility.

[0047] Hereinafter, a polarizing plate according to one embodiment of the present invention will be described.

[0048] The polarizing plate has a polarizer and an optical functional layer.

[0049] 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.

[0050] optical functional layer

[0051] 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.

[0052] The upper and lower surfaces of the optical functional layer are each entirely flat and unpatterned. Nevertheless, the optical functional layer can improve visibility and / or contrast ratio and / or brightness from the front and side. This can help improve the manufacturing process of the polarizing plate and provide a thinner film, as it does not require an optical pattern or pattern layer.

[0053] The optical functional layer comprises anisotropic diffusing particles.

[0054] Anisotropic diffusing particles include acicular particles. The acicular particles can exhibit particularly excellent visibility and contrast ratio enhancement effects by utilizing the fact that the degree to which they diffuse light incident from a backlight unit (preferably a polarizer) varies depending on the refractive index and orientation of the particles.

[0055] A detailed description of the needle-shaped particles is provided.

[0056] Figure 2 is a schematic cross-sectional view of a needle-shaped particle.

[0057] The acicular particle may be a particle having a length L and a predetermined cross-sectional diameter D, and the cross-sectional diameter D may not be uniform throughout the length L but instead decreases toward both ends of the acicular particle. The acicular particle having an inhomogeneous thickness may exhibit optical anisotropy, thereby causing light incident from a polarizer to be emitted in different directions when passing through the acicular particle.

[0058] Figure 2 illustrates a case where the cross-sectional diameter of a needle-shaped particle decreases from the center to both ends. However, depending on the manufacturing method of the needle-shaped particle, the cross-sectional diameter may be uniform toward one end, but decrease only toward one end.

[0059] It may be preferable that the acicular particles are acicular microparticles having a maximum length L in micrometers. Here, "a value in micrometers" means that the length L is at least 1 ㎛ or more. This can help improve the contrast ratio and brightness by facilitating the orientation of the acicular microparticles among the microstructures in the present invention. Nanoparticles (e.g., nanorods, acicular nanoparticles) having a length L in nanometers may not be easy to orient themselves in the present invention, so it may not be easy to obtain the effects of the present invention, and if they are included in an excessive amount to provide the same effect, optical properties such as light transmittance and haze may not be good.

[0060] In one specific example, the length L may be 10 to 50 μm, for example, 10 to 30 μm, or 15 to 28 μm. Within this range, the orientation of the needle-shaped particles in the present invention is facilitated, which may help improve contrast ratio and brightness.

[0061] In one specific example, the cross-sectional diameter D may be 0.5 to 2.0 μm, preferably 1 to 2.0 μm. In this range, the aspect ratio may increase, thereby allowing a lateral diffusion effect. The "cross-sectional diameter" may refer to the cross-sectional diameter of the acicular particles, and may refer to the maximum diameter measured at the cross-section among the acicular particles.

[0062] In one specific example, the cross-section of the needle-shaped particle may be circular, elliptical, or the like.

[0063] The acicular particles may have an average aspect ratio of 5 to 60. Within this range, it may be easy to provide the contrast ratio and brightness improvement effects of the present invention. Preferably, the average aspect ratio may be 10 to 50, more preferably 10 to 18. The "average aspect ratio" refers to the average value of the aspect ratios measured for each acicular particle, and the "aspect ratio" refers to the ratio of the length to the maximum cross-sectional diameter of the acicular particles.

[0064] The needle-shaped particles 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 this range, the particles may have an appropriate refractive index relative to the matrix described below, thereby helping to improve contrast ratio and visibility.

[0065] The needle-like particles can be organic particles, inorganic particles, organic-inorganic particles, etc. For example, needle-like particles 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., MgSO 4ㆍ 7H2O), 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.

[0066] The acicular particles may be included in the optical functional layer without being surface-modified. However, surface-modified acicular particles can improve the optical properties of the optical functional layer by further increasing the compatibility with the first resin, for example, an alloy resin, among the microstructures and the dispersibility of the particles, and can prevent the aggregation of the acicular particles, thereby facilitating the implementation of the effects of the present invention. At least 50% of the total surface area of ​​the acicular particles, for example, 60% to 100%, or 60% to 95%, can be surface-modified. Within this range, the effects of improved compatibility and dispersibility can be obtained.

[0067] In one specific example, the surface of the needle-shaped particles may be modified with one or more of a silane compound, a surfactant, and an oil. Preferably, the needle-shaped particles are surface-treated with a silane compound having a (meth)acryloyloxy group or a (meth)acrylate group, thereby improving compatibility and dispersibility with the alloy resin described below.

[0068] The silane compound having a (meth)acryloyloxy group or a (meth)acrylate group may include at least one of 3-(meth)acryloyloxypropylmethyldimethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane, 3-(meth)acryloyloxypropyl triethoxysilane, 3-(meth)acryloyloxypropyltrimethoxysilane, preferably 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropyl triethoxysilane.

[0069] According to one embodiment, the needle-shaped particles may be contained in an amount of 90% or more, for example, 95% to 100%, or 100%, of the total anisotropic diffusion particles contained in the optical functional layer. Within this range, the effects of the present invention may be easily realized. Here, '%' refers to the ratio of the weight of the needle-shaped particles to the weight of the total anisotropic diffusion particles contained in the optical functional layer.

[0070] Anisotropic diffusion particles, preferably needle-shaped particles, may be contained in the optical functional layer in an amount of 1 wt% to 30 wt%, for example, 3 wt% to 15 wt%, 3 wt% to 10 wt%, or 4 wt% to 10 wt%. Within the above range, the effects of improving contrast ratio and brightness can be obtained, and the effect of preventing the problem of the haze of the polarizing plate increasing due to excessive inclusion can be prevented.

[0071] In the present invention, anisotropic diffusion particles, for example, needle-shaped particles, are included in an optical functional layer, but instead of including the anisotropic diffusion particles in a matrix forming the optical functional layer, a plurality of microstructures including the anisotropic diffusion particles, for example, needle-shaped particles, are included in the matrix. The anisotropic diffusion particles in the microstructures are oriented in one direction. This improves the arrangement of the needle-shaped particles in a specific direction (for example, the stretching direction during the manufacture of the optical functional layer) compared to a polarizing plate including the anisotropic diffusion particles in the matrix, ultimately improving the anisotropic diffusion effect, and can further provide the effect of improving the contrast ratio.

[0072] According to one embodiment, the optical functional layer includes a matrix and a plurality of microstructures dispersed in the matrix, at least some of the plurality of microstructures include a first resin and needle-shaped particles oriented in one direction within the first resin, the matrix includes a second resin, the first resin includes an alloy-based resin, and the second resin and the alloy-based resin have a glass transition temperature difference of 10°C or less.

[0073] The matrix enhances the mechanical strength of the optically functional layer and supports the microstructures formed during their formation. Furthermore, the matrix can also enhance frontal luminance and anisotropic diffusion.

[0074] The microstructure comprises a first resin and a plurality of acicular particles oriented in one direction within the first resin. For example, the first resin can form the shape of the microstructure and, during the manufacture of the microstructure, can orient the anisotropically diffusing particles in one direction. Furthermore, the first resin can also serve to enhance frontal brightness and anisotropic diffusivity. The microstructure can be oriented so that the acicular particles are well oriented by first capturing them within the first resin.

[0075] The microstructure may have a major axis direction and a minor axis direction (wherein the major axis length is longer than the minor axis length), a cross-section in the major axis direction may be elliptical or amorphous, and a cross-section in the minor axis direction may be circular, elliptical, or amorphous. At this time, the length of the major axis direction of the microstructure may be equal to or greater than the longest length of the acicular particles, and the length of the major axis direction of the microstructure may be 3 µm or more, for example, 3 µm to 30 µm, or 5 µm to 25 µm, and the length of the minor axis direction of the microstructure may be equal to or greater than the cross-sectional diameter of the acicular particles, and the length of the minor axis direction of the microstructure may be 2 µm or less, for example, 0.1 µm to 2 µm, or 0.2 µm to 1.5 µm. In the above range, the acicular particles may be easily accommodated.

[0076] The microstructure may contain a first resin, for example, an alloy resin, in an amount of 60 to 99 wt%, for example, 70 to 99 wt%, 90 to 99 wt%, and may contain acicular particles in an amount of 1 to 40 wt%, for example, 1 to 30 wt%, 1 to 10 wt%. In the above range, the microstructure can be easily manufactured and there may be an effect of improving the contrast ratio due to the acicular particles.

[0077] In one specific example, the needle-shaped particles may be included in multiples of one or more types of microstructures, for example, two or more types.

[0078] The matrix comprises a second resin, and the microstructure comprises a first resin.

[0079] The first resin includes an alloy-based resin, and the second resin and the alloy-based resin have a glass transition temperature difference of 10°C or less.

[0080] According to one embodiment, the alloy resin may have a glass transition temperature of 100 to 120°C, for example, 110 to 115°C, and the second resin may have a glass transition temperature of 100 to 130°C, for example, 115 to 120°C. In the above range, the glass transition temperature difference of 10°C or less can be easily reached, thereby facilitating the manufacture of an optical functional layer.

[0081] According to the implementation, the alloy resin and the second resin are different from each other.

[0082] For example, the alloy resin may include at least one of polycarbonate resin and polycyclohexylene dimethylene terephthalate resin.

[0083] For example, the second resin may include at least one of a polyethylene naphthalate-based (PEN) resin and a polyethylene terephthalate-based (PET) resin.

[0084] According to one embodiment, the alloy resin may be a polycarbonate alloy (an alloy of polycyclohexylene dimethylene terephthalate (PCTG) and polycarbonate (PC)) resin, and the second resin may be a polyethylene naphthalate (PEN) resin. When the optical functional layer includes a microstructure made of the first resin and a matrix including the second resin, improvements in frontal brightness and anisotropic diffusion may be significant.

[0085] According to one embodiment, the first resin, for example, an alloy resin, has a refractive index of about 1.5 to 1.6, and the second resin, for example, a polyethylene naphthalate resin, has a refractive index higher than that of the first resin, for example, an alloy resin, and may be about 1.6 to 1.7. In this range, refractive index matching between the matrix and the microstructure may be facilitated, and the visibility improvement effect may be further enhanced.

[0086] According to one embodiment, the polyethylene naphthalate (PEN) resin may have a refractive index of about 1.65, and the polycarbonate alloy resin may have a refractive index of about 1.58.

[0087] According to one embodiment, the polycarbonate-based alloy may be composed of a mixed component of polycyclohexylene dimethylene terephthalate (PCTG) and polycarbonate. The combination of polyethylene naphthalate and the polycarbonate-based alloy is designed (intrinsic viscosity of 0.01 or more) to have a difference in melt flowability of the polymers, that is, a difference in viscosity, so that microstructures can be arranged inside the matrix component, and preferably, the flowability of the matrix component is better than that of the microstructure component. According to one embodiment, the polycarbonate-based alloy may include 50 to 90 wt%, for example, 55 to 70 wt%, of a polycarbonate-based resin, and 10 to 50 wt%, for example, 30 to 45 wt%, of polycyclohexylene dimethylene terephthalate.

[0088] According to one embodiment, the alloy resin may be included in the first resin at 95 wt% or more, for example, 99 to 100 wt%.

[0089] Among the optical functional layers, the matrix may be included in an amount of 50 to 95 wt%, for example, 60 to 90 wt%, and the microstructure may be included in an amount of 5 to 50 wt%, for example, 10 to 40 wt%. In the above ranges, frontal brightness and anisotropic diffusion may be improved.

[0090] The microstructures in the optical functional layer may be randomly dispersed within the matrix. However, the microstructures may be oriented within the matrix in the same direction as the orientation direction of the needle-shaped particles.

[0091] According to one embodiment, the microstructure may be, for example, an elliptical cross-section having a major axis and a minor axis in the thickness direction.

[0092] Figure 1 is a conceptual diagram of a polarizing plate according to one implementation.

[0093] Referring to FIG. 1, a polarizing plate includes a polarizer (100) and an optical functional layer (200) laminated on one surface of the polarizer (100). The optical functional layer (200) includes a matrix (210) and a microstructure (220). The microstructure (220) includes a first resin (221) and needle-shaped particles (222).

[0094] Referring to FIG. 1, the light absorption axis direction (indicated by the X-axis in FIG. 1) of the polarizer (100) may be substantially the same direction as the orientation direction of the needle-shaped particles (222) in the microstructure (220) of the optical functional layer (200).

[0095] Here, 'substantially the same direction' means that when the light absorption axis direction of the polarizer is 0°, the orientation direction of the anisotropic diffusing particles is between -5 and +5°, for example, between -3 and +3°, or 0°. In one specific example, the light absorption axis direction of the polarizer is the machine direction (MD) of the polarizer. That is, in Fig. 1, the X-axis is MD, and the Y-axis is TD.

[0096] In one specific example, the optical functional layer may have a thickness of 5 to 50 μm, preferably 5 to 20 μm, and more preferably 5 to 15 μm.

[0097] 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.

[0098] (i) Polarizer

[0099] 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.

[0100] 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.

[0101] 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.

[0102] (ii) protective layer

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] The protective layer may be a first protective layer, a second protective layer, or a third protective layer, as described below.

[0113] (iii) adhesive layer and / or adhesive layer;

[0114] The adhesive layer and / or bonding layer can bond or adhere a polarizer, an optical functional layer, a protective layer, a functional film, etc.

[0115] 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.

[0116] 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.

[0117] (iv) Functional film

[0118] 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.

[0119] 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.

[0120] According to one implementation, the polarizing plate may include a polarizer; and an optical functional layer laminated on a light-emitting surface of the polarizer.

[0121] According to another embodiment, the polarizing plate may include a polarizer; and an optical functional layer and a first protective layer sequentially laminated on a light-emitting surface of the polarizer.

[0122] According to another embodiment, the polarizing plate may include a polarizer; an optical functional layer and a functional coating layer sequentially laminated on the light-emitting surface of the polarizer.

[0123] According to another embodiment, the polarizing plate may include a polarizer; a second protective layer, an optical functional layer, and a first protective layer sequentially laminated on the light-emitting surface of the polarizer.

[0124] According to another embodiment, the polarizing plate may include a polarizer; a second protective layer, an optical functional layer, and a first protective layer sequentially laminated on a light-emitting surface of the polarizer; and a third protective layer laminated on a light-incident surface of the polarizer.

[0125] Each layer of the above-described polarizing plate can be laminated by an adhesive layer, an adhesive layer, etc., if necessary.

[0126] The optical display device of the present invention includes the polarizing plate of the present invention.

[0127] 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.

[0128] 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.

[0129] The optical display device may be a foldable or flexible optical display device or a non-foldable or non-flexible optical display device.

[0130]

[0131] 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.

[0132]

[0133] Example 1

[0134] (1) 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 nx: 1.53, refractive index ny: 1.68, refractive index nx: 1.68) was prepared.

[0135] A composition was prepared by mixing the mixture of the above-mentioned needle-shaped particles in a polycyclohexylene dimethylene terephthalate (PCTG, refractive index: 1.56, TAK) resin at a predetermined ratio, and the composition was injected into an extrusion unit to prepare a high-concentration master batch. At this time, the master batch contains 80 wt% of PCTG and 20 wt% of needle-shaped particles.

[0136] Then, a polycarbonate resin (PC, refractive index: 1.58) was mixed into the master batch, and the mixture was then fed back into the extrusion unit and heated at 250°C to produce a component for producing a microstructure. At this time, the component for producing a microstructure includes needle-shaped particles and a PC alloy resin (glass transition temperature: 118°C) containing 60 wt% PC and 40 wt% PCTG.

[0137] 60 parts by weight of polyethylene naphthalate (PEN, refractive index: 1.65, glass transition temperature: 118°C) and 40 parts by weight of the above-described component for producing a microstructure were mixed and placed in an extrusion unit, and then extruded at an extrusion temperature of 230 to 250°C to produce a sheet of a certain thickness.

[0138] The above sheet was sequentially stretched 5 times in the mechanical direction of the sheet and 2 times in the width direction to produce an optical functional layer.

[0139] Among the optical functional layers, the matrix: microstructure is included in an amount of 60 parts by weight: 40 parts by weight out of a total of 100 parts by weight of the optical functional layer, and the needle-shaped particles are included in an amount of 3% by weight of the optical functional layer.

[0140] (2) A polyvinyl alcohol film was stretched 3 times in the mechanical direction of the film at 60°C, iodine was adsorbed, and then stretched 2.5 times in the mechanical direction of the film in a boric acid aqueous solution at 40°C to manufacture a polarizer (thickness: 13 μm, light transmittance: 44%).

[0141] (3) The optical functional layer was laminated on the upper surface of the manufactured polarizer, and a cyclic olefin polymer (COP) film was laminated on the lower surface using an adhesive, thereby manufacturing a polarizing plate in which the optical functional layer - polarizer - cyclic olefin polymer film were sequentially laminated.

[0142]

[0143] Examples 2 to 9

[0144] A polarizing plate was manufactured in the same manner as in Example 1, except that the content of polyethylene naphthalate and microstructures in Example 1 was changed as shown in Table 1 below, and the content of needle-shaped particles in the optical functional layer was changed as shown in Table 1 below.

[0145]

[0146] Comparative Example 1

[0147] A polarizing plate was manufactured in the same manner as in Example 1, except that the mixture of needle-shaped particles was not used. The microstructure in the optical functional layer includes only an alloy resin of PC and PCTG.

[0148]

[0149] Comparative Example 2

[0150] Polycyclohexylene dimethylene terephthalate (PCTG, refractive index: 1.56, TAK) resin was mixed with polycarbonate (PC) resin (refractive index: 1.58) and introduced into an extrusion unit. A sheet of a certain thickness was manufactured by extrusion at an extrusion temperature of 230 to 250°C. The sheet contains an alloy resin of PC and PCTG.

[0151] The above sheet was stretched at a stretching ratio of 5 times in the mechanical direction of the sheet and at a stretching ratio of 2 times in the width direction to produce an optical functional layer, and a polarizing plate was produced using the same method as Example 1.

[0152]

[0153] Comparative Example 3

[0154] 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 nx: 1.53, refractive index ny: 1.68, refractive index nx: 1.58) was prepared.

[0155] A composition was prepared by mixing the mixture of the above-mentioned needle-shaped particles in a polycyclohexylene dimethylene terephthalate (PCTG, refractive index: 1.56, TAK) resin at a predetermined ratio, and the composition was injected into an extrusion unit to prepare a high-concentration master batch.

[0156] Then, a polycarbonate resin (refractive index 1.58) was mixed into the master batch and again fed into the extrusion section, and then extruded at an extrusion temperature of 230 to 250°C to produce a sheet of a certain thickness. The sheet was stretched at a stretching ratio of 5 times in the mechanical direction of the sheet to produce an optically functional layer. Then, a polarizing plate was produced using the same method as in Example 1. The matrix of the optically functional layer includes an alloy resin of PC and PCTG.

[0157]

[0158] Comparative Example 4

[0159] Polyethylene naphthalate (refractive index: 1.65) was introduced into the extrusion section and extruded at an extrusion temperature of 230 to 250°C to produce a sheet of a certain thickness. The sheet was stretched at a stretching ratio of 5 times in the mechanical direction and 2 times in the width direction to produce an optical functional layer. A polarizing plate was produced using the same method as in Example 1.

[0160]

[0161] Comparative Example 5

[0162] 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 nx: 1.53, refractive index ny: 1.68, refractive index nx: 1.58) was prepared.

[0163] A composition was prepared by mixing the mixture of the above-mentioned needle-shaped particles in polyethylene naphthalate (refractive index: 1.65) at a predetermined ratio, and the composition was fed into an extrusion unit to prepare a high-concentration master batch. After feeding into the extrusion unit, it was extruded at an extrusion temperature of 230 to 250°C to prepare a sheet of a predetermined thickness. The sheet was stretched in the mechanical direction of the sheet at a stretch ratio of 5 times to prepare an optical functional layer. A polarizing plate was prepared in the same manner as in Example 1.

[0164]

[0165] Comparative Example 6

[0166] A high-concentration master batch was manufactured by adding polyethylene naphthalate (refractive index: 1.65) to the extrusion section.

[0167] Then, polycarbonate resin (PC, refractive index: 1.58) and polycyclohexylene dimethylene terephthalate (PCTG, refractive index: 1.56, TAK) were mixed into the master batch, and the mixture was put into the extrusion unit again and extruded at an extrusion temperature of 230 to 250°C to produce a sheet of a certain thickness. The sheet was stretched at a stretching ratio of 5 times in the mechanical direction of the sheet to produce an optical functional layer. A polarizing plate was produced in the same manner as in Example 1. The matrix of the optical functional layer includes an alloy resin of PC and PCTG.

[0168]

[0169] Comparative Examples 7 to 9

[0170] A polarizing plate was manufactured in the same manner as in Example 1, except that the content of needle-shaped particles in Comparative Example 6 was changed as shown in Table 1 below.

[0171]

[0172] Reference Example 1

[0173] A polarizing plate was manufactured in the same manner as in Example 1, except that the optical functional layer was not included in Example 1.

[0174]

[0175] For the polarizing plates manufactured in the examples and comparative examples, a model for measuring the viewing angle below was manufactured and the physical properties shown in Table 1 below were evaluated.

[0176] A viewing-side polarizing plate was removed from a liquid crystal panel model UN55KS8000F (55 inches, Samsung Electronics TV), and a viewing-side polarizing plate was laminated with the polarizing plate manufactured in the examples and comparative examples to produce a model for measuring viewing angles. Among the models for measuring viewing angles, the light-source-side polarizing plate was laminated in the order of COP film - polarizer - PET film from the liquid crystal panel.

[0177]

[0178] The following properties were evaluated, and the results are shown in Table 1 below.

[0179] (1) Confirmation of microstructures within the optical functional layer:

[0180] The cross-sections of the optical functional layers manufactured in the examples and comparative examples in the direction of the light absorption axis and light transmission axis of the polarizer were measured using SEM, and the results are shown in FIGS. 3 to 6.

[0181] Fig. 3 is a cross-sectional view of an optical functional layer in the direction of the light absorption axis of a polarizer in a polarizing plate according to one embodiment, and Fig. 4 is an enlarged cross-sectional view of Fig. 3. Fig. 5 is a cross-sectional view of an optical functional layer in the direction of the light transmission axis of a polarizer in a polarizing plate according to one embodiment, and Fig. 6 is an enlarged cross-sectional view of Fig. 5. As shown in Figs. 3 and 4, it can be confirmed that the acicular particles and the microstructures including the acicular particles are oriented in one direction. As shown in Figs. 5 and 6, it can be confirmed through the cross-sections of the acicular particles that the acicular particles are oriented in the direction of the light absorption axis of the polarizer.

[0182] (2) Frontal luminance: A liquid crystal display (LCD) including a one-sided edge-type LED light source (same configuration as a Samsung TV (55 inches, model name: UN55KS8000F) except for the configuration of the liquid crystal display module of the Examples and Comparative Examples) was manufactured by assembling an LED light source, a light guide plate, and a model for measuring the viewing angle. The luminance was measured at the front (0°, 0°) in a spherical coordinate system using EZCONTRAST X88RC (EZXL-176R-F422A4, ELDIM). The relative ratio of the luminance at the front (0°, 0°) measured with the polarizing plate of Reference Example 1 was calculated.

[0183] (3) Anisotropic diffusion: A module for a liquid crystal display was manufactured using the same method as in (2). Luminance was measured in white mode at the front (0°, 0°) and side (60°, 0°) in a spherical coordinate system using EZCONTRAST X88RC (EZXL-176R-F422A4, ELDIM). The ratio of the luminance measured at the side (60°, 0°) to the luminance measured at the front (0°, 0°) in white mode was calculated.

[0184] Whether the first resin needle-shaped particle is included in the matrix microstructure Content of needle-shaped particles Matrix / microstructure content ratio Frontal luminance Anisotropic diffusion Example 1 PENPC + PCTG included 360 / 4080 26 Example 2 PENPC + PCTG included 560 / 4078 28 Example 3 PENPC + PCTG included 760 / 4076 30 Example 4 PENPC + PCTG included 380 / 2080 23 Example 5 PENPC + PCTG included 580 / 2077 24 Example 6 PENPC + PCTG included 780 / 2076 25 Example 7 PENPC + PCTG included 390 / 1081 22 Example 8 PENPC + PCTG included 590 / 1078 23 Example 9 PENPC + PCTG included 79 0 / 107724Comparison Example 1PENPC+PCTGNot Included-60 / 409319Comparison Example 2PC+PCTGNot Included-60 / 409517Comparison Example 3PC+PCTGIncluded560 / 409418Comparison Example 4PENNot Included-60 / 409517Comparison Example 5PENIncluded560 / 409418Comparison Example 6PC+PCTGPENNot Included-60 / 406019Comparison Example 7PC+PCTGPENIncluded360 / 405823Comparison Example 8PC+PCTGPENIncluded560 / 405524Comparison Example 9PC+PCTGPENIncluded760 / 405425

[0185]

[0186] *Particle content: Content of needle-shaped particles (CaCO3) in the optical functional layer (weight%)

[0187]

[0188] As shown in Table 1 above, the polarizing plate according to one embodiment can have a frontal luminance of 75 or more and an anisotropic diffusion of 20 or more. Therefore, although not shown in Table 1 above, it is expected to provide an effect of improving visibility and improving the contrast ratio from the front and side.

[0189] However, the polarizing plate of the comparative example that did not have the optical functional layer of the embodiment had both lower frontal luminance and anisotropic diffusion properties than the embodiment.

[0190]

[0191] 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 laminated on one surface of the polarizer, The optical functional layer comprises a matrix and a plurality of microstructures dispersed in the matrix, At least some of said plurality of microstructures comprise a first resin and needle-shaped particles oriented in one direction within said first resin, The above matrix comprises a second resin, The above first resin includes an alloy resin, A polarizing plate wherein the difference in glass transition temperature between the second resin and the alloy resin is 10℃ or less.

2. A polarizing plate in accordance with claim 1, wherein the optical functional layer is a contrast ratio or brightness improvement layer.

3. A polarizing plate according to claim 1, wherein the upper and lower surfaces of the optical functional layer are each entirely flat.

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

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

7. A polarizing plate according to claim 1, wherein the needle-shaped particles are contained in an amount of 1 to 30 wt% of the optical functional layer.

8. A polarizing plate in the first paragraph, wherein the needle-shaped particles are included as a plurality of the microstructures.

9. A polarizing plate in the first paragraph, wherein the microstructure is a structure having a long-axis direction and a short-axis direction.

10. A polarizing plate in the first paragraph, wherein the microstructure is oriented in the matrix in the same direction as the orientation direction of the needle-shaped particles.

11. A polarizing plate in accordance with claim 1, wherein when the light absorption axis direction of the polarizer is 0°, the orientation direction of the needle-shaped particles is between -5 and +5°.

12. A polarizing plate in the first paragraph, wherein the alloy resin has a glass transition temperature of 100 to 120°C, and the second resin has a glass transition temperature of 100 to 130°C.

13. A polarizing plate in the first paragraph, wherein the alloy resin includes at least one of polycarbonate resin and polycyclohexylene dimethylene terephthalate.

14. A polarizing plate according to claim 13, wherein the alloy resin comprises 50 to 90 wt% of a polycarbonate resin and 10 to 50 wt% of polycyclohexylene dimethylene terephthalate.

15. A polarizing plate in the first paragraph, wherein the second resin comprises at least one of a polyethylene naphthalate-based resin and a polyethylene terephthalate-based resin.

16. A polarizing plate in the first paragraph, wherein the matrix of the optical functional layer is included in an amount of 50 to 95 wt%, and the microstructure is included in an amount of 5 to 50 wt%.

17. A polarizing plate according to claim 1, wherein the polarizing plate comprises at least one of a protective layer, an adhesive layer, an adhesive layer, a functional film, and a functional coating layer.

18. An optical display device comprising a polarizing plate according to any one of claims 1 to 17.

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