Optical film and display comprising the same

Abstract

The present invention relates to an optical film, and more specifically, it can improve the left and right viewing angles of a display device and can uniformly exhibit the viewing angle improvement effect even when manufactured in a large area, and can minimize color variation along with improved contrast ratio without degrading frontal brightness characteristics while improving the viewing angle.

Description

Technology Field

[0001] The present invention relates to an optical film and a display device including the same. Background Technology

[0002] Liquid crystal displays operate by light from a backlight unit being emitted through a liquid crystal panel. Therefore, while the brightness and contrast ratio (CR) are excellent on the front of the screen, they are generally inferior on the sides compared to the front.

[0003] To address this, there are attempts to increase contrast ratio or brightness from the sides by modifying the liquid crystal panel or liquid crystal structure. However, increasing the side contrast ratio or brightness inevitably leads to a decrease in frontal contrast ratio or brightness. Therefore, it is necessary to increase the side contrast ratio or brightness while minimizing the reduction in frontal contrast ratio or brightness.

[0004] Meanwhile, there is a method of diffusing light to improve the viewing angle, and for this purpose, a method has been proposed to enhance light diffusion by including inorganic particles, as an example. However, spherical inorganic particles provided in optical films make it difficult to secure a sufficient viewing angle, or even if secured, may reduce brightness, and have almost no effect on improving contrast ratio.

[0005] As another example, it has been studied that inorganic particles having an aspect ratio greater than 1 provided in an optical film can increase light diffusivity and simultaneously exhibit anisotropic diffusion characteristics compared to spherical inorganic particles. However, it is not easy to align the long axis direction of each of the numerous inorganic particles contained within the body of the film so that they face a specific direction. Furthermore, inorganic particles that are not uniformly aligned in a specific direction within the film may exhibit anisotropic diffusion, but when viewed as a whole optical film, it is difficult to exhibit anisotropic diffusion, and consequently, there is a problem in that it is difficult to secure a sufficient viewing angle. Prior art literature

[0006] Republic of Korea Published Patent Application No. 2012-0078508 The problem to be solved

[0007] The present invention was devised to solve the aforementioned problems and aims to provide an optical film capable of improving the left and right viewing angles of a display device and uniformly exhibiting a viewing angle improvement effect even when manufactured in a large area.

[0008] In addition, another objective of the present invention is to provide an optical film that improves the viewing angle while simultaneously improving the contrast ratio and minimizing color variation without degrading the frontal brightness characteristics. means of solving the problem

[0009] To solve the above-mentioned problem, the present invention provides an optical film having an anisotropic diffusion layer comprising: a polymer matrix; and a plurality of dispersions, each having a long axis direction that is the x-axis direction among the x-axis, y-axis, and z-axis mutually perpendicular within the matrix and is positively dispersed in the other two axis directions, and comprising a polymer dispersion and a non-polymer dispersion having an average aspect ratio of 3.0 or more.

[0010] According to one embodiment of the present invention, the plurality of dispersed bodies form a plurality of arrays in which two or more dispersed bodies are arranged in a single column in the z-axis direction, and each of the plurality of arrays can be spaced apart in the y-axis direction and dispersed.

[0011] In addition, the spacing in the y-axis direction between adjacent arrays may be 100 to 500 nm.

[0012] In addition, the spacing in the z-axis direction between adjacent dispersed elements within a single array may be 30 to 100 nm.

[0013] In addition, the thickness of the polymer dispersion in the z-axis direction at the cross-section of the anisotropic diffusion layer in the yz plane may be 70 to 200 nm.

[0014] In addition, the above-mentioned inorganic particles may be located inside the polymer dispersion.

[0015] In addition, the polymer matrix may include a crystalline or semicrystalline resin, and the polymer dispersion may include an amorphous resin.

[0016] In addition, the inorganic particles may have an average length of 3 to 15 μm and an average diameter of 0.5 to 2.0 μm.

[0017] In addition, the above inorganic particles have an average length of 3 to 15 μm, and inorganic particles with a length of 2.5 μm or less may be included in an amount of 17% or less of the total inorganic particles.

[0018] In addition, the above-mentioned inorganic particles may be contained in an amount of 0.5 to 5 weight percent based on the total weight of the anisotropic diffusion layer.

[0019] In addition, the surface of the above-mentioned inorganic particle may be modified with a silane-based material containing epoxy groups.

[0020] In addition, a buffer layer derived from a polymer dispersion may be interposed at least in part of the interface between the side surface of the inorganic particle along the long axis direction of the inorganic particle and the polymer matrix.

[0021] In addition, the above anisotropic diffusion layer can be formed through melt extrusion.

[0022] In addition, the matrix and polymer dispersion may be included in a weight ratio of 6 to 9.8: 4 to 0.2.

[0023] In addition, the above anisotropic diffusion layer may have a thickness of 150㎛ or less.

[0025] In addition, the present invention provides a polarizing plate disposed on a light-emitting surface of a liquid crystal panel, wherein the polarizing plate comprises an absorption polarizing film and an optical film according to the present invention disposed on a light-emitting surface of the absorption polarizing film.

[0027] In addition, the present invention provides a display device comprising a liquid crystal panel and a polarizing plate according to the present invention disposed on at least the light-emitting surface of the liquid crystal panel.

[0029] In addition, the present invention provides a display device comprising a self-emissive display panel and an optical film according to the present invention disposed on at least the light-emitting surface of the self-emissive display panel. Effects of the invention

[0030] The optical film of the present invention can improve the left and right viewing angles of a display device and can uniformly exhibit the effect of improving the viewing angle even when manufactured over a large area. Furthermore, while improving the viewing angle, it can minimize color fluctuations along with enhancing the contrast ratio without degrading the frontal brightness characteristics. Moreover, it can minimize or prevent voids formed on the side of inorganic particles that reduce the aspect ratio of the dispersion, thereby preventing a decrease in anisotropic diffusion and brightness reduction caused by voids resulting from the reduction in the aspect ratio of the dispersion. In addition, as it is suitable for mass production over a large area, it can be widely used as an optical component for various display devices. Brief explanation of the drawing

[0031] FIG. 1 is a perspective view of an optical film according to one embodiment of the present invention. Figure 2 is a schematic cross-sectional view along the YY' boundary line of the optical film according to Figure 1. FIG. 3 is a schematic cross-sectional view along the YY' boundary line of an optical film according to another embodiment of the present invention. Figure 4 is a schematic cross-sectional view along the XX' boundary line of the optical film according to Figure 1. FIG. 5 is a schematic cross-sectional view of a polarizing plate according to one embodiment of the present invention. FIG. 6 is a cross-sectional schematic diagram of a liquid crystal display according to one embodiment of the present invention. FIG. 7 is a schematic diagram illustrating the alignment of inorganic particles in the long axis direction within an anisotropic diffusion layer according to one embodiment of the present invention. FIGS. 8 and 9 are schematic diagrams of a part of a manufacturing apparatus for manufacturing an optical film according to one embodiment of the present invention. Specific details for implementing the invention

[0032] Hereinafter, embodiments of the present invention are described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. The present invention may be embodied in various different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and the same reference numerals are assigned to identical or similar components throughout the specification. Furthermore, the present invention is not limited by the size or shape of a configuration shown in the drawings. For example, in FIG. 4, the cross-sectional shape of the inorganic particle is shown as rectangular, but it is not limited thereto. Also, for example, in FIG. 4, the polymer dispersion is shown as continuous, but at least a portion of the polymer dispersion may not be continuous so as to extend from one end to the other of the anisotropic diffusion layer.

[0034] Referring to FIGS. 1 to 4, an optical film (200) according to one embodiment of the present invention includes an anisotropic diffusion layer (100) and may further include a skin layer (110) disposed on one or both sides of the anisotropic diffusion layer (100).

[0036] The above anisotropic diffusion layer (100) performs the function of anisotropically diffusing light incident on the optical film (200). Specifically, when light is incident on a plane formed by the x-axis and the y-axis, it can be anisotropically diffused more significantly in the y-axis direction, which is perpendicular to the x-axis direction where the major axis direction of the disperser is aligned, than in the x-axis direction, and emitted to the opposite side facing the incident surface. Alternatively, when light is incident on a plane formed by the x-axis and the y-axis, it can be anisotropically diffused more significantly in the x-axis direction, which is the axis direction where the major axis direction of the disperser is aligned, than in the y-axis direction, and emitted to the opposite side facing the incident surface.

[0038] To perform these optical functions, the anisotropic diffusion layer (100) comprises a polymer matrix (10) and a plurality of dispersed bodies (20) located within the polymer matrix (10).

[0039] The polymer matrix (10) is formed as a body that disperses and supports a dispersion (20) exhibiting anisotropic diffusion characteristics, and is formed with a polymer component including a first polymer as the main component. Here, the main component may be, for example, 51% by weight or more of the matrix weight, or, for other examples, 60% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, 95% by weight or more, or 99% by weight or more. The first polymer may be used without limitation as a known polymer used as a conventional optical film. The first polymer may be, for example, one or more mixtures or two or more copolymers selected from the group consisting of polyethylene naphthalate (PEN), copolyethylene naphthalate (co-PEN), polyethylene terephthalate (PET), polycarbonate (PC), polycarbonate (PC) alloy, polystyrene (PS), polymethyl methacrylate (PMMA), polybutylene terephthalate (PBT), polypropylene (PP), polyethylene (PE), acrylonitrile butadiene styrene (ABS), polyurethane (PU), polyimide (PI), polyvinyl chloride (PVC), styrene-acrylonitrile mixture (SAN), ethylene vinyl acetate (EVA), polyamide (PA), polyacetal (POM), phenol, epoxy (EP), urea (UF), melamine (MF), unsaturated polyester (UP), and cycloolefin polymers.

[0041] Additionally, the plurality of dispersed bodies (20) dispersed within the matrix (10) described above include a polymer dispersed body (21) and a non-polymer dispersed body (22) containing inorganic particles. Each of the polymer dispersed body (21) and the non-polymer dispersed body (22) has a shape with an elongated length in one direction, and among the mutually perpendicular x-axis, y-axis, and z-axis within the matrix (10), the long axis direction, which is the direction in which the length of each polymer dispersed body (21) and the non-polymer dispersed body (22) is longest, is arranged in the x-axis direction. A dispersed body in which the long axis direction is arranged in the x-axis direction can anisotropically diffuse light transmitted through the dispersed body in the y-axis direction, which is perpendicular to the x-axis direction. Alternatively, although not conventional, transmitted light can be anisotropically diffused in the x-axis direction, which becomes the long axis direction, by changing stretching conditions, etc. In addition, the dispersion (20) can be positively dispersed in the other two axis directions, the y-axis and the z-axis, and this may be advantageous for achieving superior anisotropic diffusion compared to cases where multiple dispersions are randomly dispersed in the y-axis and z-axis directions.

[0042] Here, the meaning that a plurality of dispersed bodies (20) are arranged such that the x-axis direction becomes the major axis direction among the three mutually perpendicular x-axis, y-axis, and z-axis within the matrix (10) does not mean that the major axis direction of all dispersed bodies (20) is arranged to be exactly parallel to the x-axis, but means that the direction of the major axis that becomes the major axis direction of a significant number of dispersed bodies (20) is substantially parallel to the x-axis direction, and where substantially parallel means, for example, in the case of a polymer dispersed body (21), the angle formed between the major axis direction and the x-axis may be less than 10°, less than 5°, less than 3°, or for another example, less than 1°. Also, in the case of a non-polymer dispersed body (22), the angle formed between the major axis direction and the x-axis may be 15° or less, 10° or less, or for another example, 5° or less.

[0044] Additionally, multiple dispersed bodies (20) are positively dispersed in the remaining two axis directions, where positive dispersion means that multiple dispersed bodies (20) are arranged in a distributed pattern such as a grid in the y-axis and z-axis directions, which are the remaining two axes. For example, as shown in FIGS. 2 and 3, multiple dispersed bodies (20) form multiple arrays (A1, A2, A3, A4) in which two or more dispersed bodies (20) are arranged in a line in the z-axis direction, and each of the multiple arrays (A1, A2, A3, A4) can be spaced apart in the y-axis direction. In addition, the number of dispersions (20) provided in each of the multiple arrays (A1, A2, A3, A4) and the arrangement of the arrays (A1, A2, A3, A4) with controlled numbers in the y-axis direction may form a predetermined pattern. For example, the total sum of the polymer dispersions (21) and non-polymer dispersions (22) provided in each array may be the same. However, considering the thickness (or diameter) in the z-axis direction of the polymer dispersions (21) and non-polymer dispersions (22) and the spacing between the dispersions, the non-polymer dispersions (22) provided in the first array (A1) as shown in FIG. 2 may be regularly dispersed so that two polymer dispersions (21) correspond in the z-axis direction in the adjacent second array (A2). Alternatively, if the thickness (or diameter) in the z-axis direction of the polymer dispersion (21) and the non-polymer dispersion (22) is similar, the polymer dispersion (21) may be regularly dispersed so that the non-polymer dispersion (22) provided in one array corresponds to the position in the z-axis direction of the adjacent array. Alternatively, the same dispersion, for example, all polymer dispersion (21) or all non-polymer dispersion (22), may be regularly dispersed so that the same dispersion is provided at the same position in the z-axis direction in each array on the yz cross-section of the anisotropic diffusion layer (100).

[0045] Additionally, at least one non-polymer dispersion (22) may be provided in each array, so that all arrays are provided with the non-polymer dispersion (22), or the array adjacent to one array that is provided with the non-polymer dispersion (22) may not be provided with the non-polymer dispersion (22), and may be provided alternately.

[0046] In addition, as shown in FIG. 3, the total number of dispersion bodies (20) provided in each array may differ among the multiple arrays (A3, A4), and arrays with different numbers may be regularly arranged in a predetermined pattern in the y-axis direction, and the present invention does not specifically limit the specific pattern or rule regarding the dispersion.

[0048] For example, the spacing between multiple arrays (A1, A2, A3, A4) may all be the same, or they may be configured differently to have a predetermined regular pattern. In this case, the spacing in the y-axis direction between adjacent arrays may be 100 to 500 nm, thereby achieving improved anisotropic diffusion. If the spacing between arrays is less than 100 nm, the amount of light to be transmitted decreases rapidly, raising concerns about a decrease in brightness, and if it exceeds 500 nm, there is a concern that the anisotropic diffusion effect may be reduced. In this case, the spacing between adjacent arrays refers to the shortest distance in the y-axis direction between the reference lines of each array, based on the dispersion located at the outermost edge in the y-axis direction, taking into account the width of the dispersion within each array in the y-axis direction.

[0049] Additionally, the spacing in the z-axis direction between adjacent dispersions (20) within one array may be 1 to 200 nm, more preferably 30 to 100 nm, and more preferably 40 to 100 nm. If the spacing in the z-axis direction exceeds 200 nm, there is a concern that the anisotropic diffusion effect may be reduced, and if the spacing in the z-axis direction is less than 1 nm, aggregation may occur between the polymer dispersion flows during the manufacturing process, making it difficult to align the long axis direction of the non-polymer dispersion in the x-axis direction or to implement the desired positive dispersion pattern.

[0051] Meanwhile, when the dispersion (20) is positively dispersed, the spacing between the dispersions (20) in the z-axis and y-axis directions can be arranged according to a set rule, and this can be more advantageous for improving and controlling anisotropic diffusion.

[0053] The polymer dispersion (21) is formed by containing a second polymer as the main component and may have a shape such as a long rod-shaped and / or fiber-shaped structure in one direction, thereby performing an anisotropic diffusion function that diffuses transmitted light in a direction perpendicular to the one direction. For example, the main component may be 51% by weight or more based on the total weight of the polymer dispersion, and for another example, 60% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, 95% by weight or more, or 99% by weight or more.

[0054] Additionally, specifically, in a cross section perpendicular to the TD direction of the optical film, in other words, in a cross section of the anisotropic diffusion layer (100) along the XX' boundary line shown in FIG. 4, the average aspect ratio (a / b), which is the ratio between the average length of the major axis (a) of the polymer dispersion (21) and the average length of the minor axis (b) perpendicular to the major axis, may be greater than 100, or as another example, greater than 1,000, greater than 10,000, or greater than 100,000. The average length of the minor axis (b) refers to the length of the largest line segment among the lengths of the line segments connecting the perimeter within the cross section perpendicular to the major axis. Meanwhile, although the polymer dispersion (21) is shown as continuous in FIG. 4, one or more of them may be discontinuous.

[0056] Additionally, the cross-sectional shape of the polymer dispersion (21) based on the cross-section plane, which is the yz plane of the anisotropic diffusion layer (100) corresponding to the cross-section along the YY' boundary line shown in FIG. 2, may be circular or elliptical. In this case, if the cross-sectional shape of the polymer dispersion (21) is elliptical, the average cross-sectional aspect ratio (c / d), which is the ratio of the average length of the major axis (c) to the average length of the minor axis (d) of the ellipse, may be greater than 1 and less than or equal to 350, but is not limited thereto. Here, the average length of the minor axis (d) refers to the average value of the length of the minor axis when the axis that perpendicularly bisects the major axis is called the minor axis.

[0058] Additionally, based on the cross-section plane of the anisotropic diffusion layer (100), which is the yz plane, the width and thickness of the portion of the polymer dispersion (21) that does not contain inorganic particles may be, for example, 10 to 200 nm and 2 to 200 nm, respectively. Here, the width of the polymer dispersion (21) refers to the width of the portion that does not contain inorganic particles projected onto a two-dimensional plane when the polymer dispersion (21) is viewed from the z-axis direction, and it should be noted that the width of the polymer dispersion (21), which has a shape other than a circle, for example, an ellipse, in the cross-section plane, is distinguished from the major axis length. Additionally, the thickness of the polymer dispersion (21) refers to the length of the longest line segment connecting the perimeter of the cross-section of the polymer dispersion parallel to the z-axis direction when viewed from the cross-section plane of the polymer dispersion (21) in the cross-section plane of the anisotropic diffusion layer (100), which is the yz plane.

[0060] Additionally, the second polymer, which is the subject forming the polymer dispersion (21), can be any known polymer used as a conventional optical film without limitation. For example, the second polymer may be one or more of polyethylene naphthalate (PEN), copolyethylene naphthalate (co-PEN), polyethylene terephthalate (PET), polycarbonate (PC), polycarbonate (PC) alloy, polystyrene (PS), polymethyl methacrylate (PMMA), polybutylene terephthalate (PBT), polypropylene (PP), polyethylene (PE), acrylonitrile butadiene styrene (ABS), polyurethane (PU), polyimide (PI), polyvinyl chloride (PVC), styrene-acrylonitrile blend (SAN), ethylene vinyl acetate (EVA), polyamide (PA), polyacetal (POM), phenol, epoxy (EP), urea (UF), melanin (MF), unsaturated polyester (UP), and cycloolefin polymer, or two or more copolymers.

[0062] Additionally, the polymer dispersion (21) is contained in multiple numbers within the matrix (10), and, for example, the polymer dispersion (21) has a unit area (1 μm) within the yz cross-section of the matrix (10). 2 It can contain 10 to 200 pieces per )

[0064] Meanwhile, the polymer dispersion (21) can perform a guide function to align the long axis direction of the inorganic particles described below to the x-axis direction within the matrix (10) in addition to the anisotropic diffusion function described above. Specifically, in the manufacturing process, inorganic particles may be extruded through a die in a composite state with a first polymer that forms the matrix or with a second polymer that forms the polymer dispersion. If the inorganic particles are extruded in a composite state with the second polymer, and the inorganic particles are confined inside the molten second polymer that becomes the polymer dispersion (21) so as not to move toward the molten first polymer that becomes the matrix (10) during extrusion, then as the polymer dispersion (21) gradually increases in length in the MD direction, the long axis direction of the inorganic particles may be aligned in the MD direction corresponding to the alignment of the polymer dispersion (21). Furthermore, as the length of the polymer dispersion (21) increases further through the extrusion process and / or the stretching process, the long axis direction of the inorganic particles may be aligned substantially parallel to the long axis direction of the polymer dispersion (21) in the MD direction, or in other words, in the x-axis direction of the matrix (10). Accordingly, although the anisotropic diffusion layer (100) is implemented through melt extrusion, the long axis direction of the inorganic particles can be guided and aligned to become the x-axis direction through the guide function of the second polymer, and as a result, the non-polymer dispersion (22), which is an inorganic particle, can be located inside the polymer dispersion (21).

[0066] Additionally, when the length of the polymer dispersion (21) increases during the process of the polymer dispersion (21) performing a guide function to align the long axis direction of the inorganic particles, the diameter of the region of the polymer dispersion (21) where the inorganic particles are not located may be smaller than the diameter of the region of the polymer dispersion (21) where the inorganic particles are located. On the other hand, the region of the polymer dispersion (21) where the inorganic particles are located may have a diameter larger than the diameter of the inorganic particles due to the inorganic particles.

[0068] In addition, the second polymer, which is the subject forming the polymer dispersion (21), can function as a buffer layer to suppress lateral voids that may occur when the long axis direction of the inorganic particles is considered as the upper / lower side.

[0069] Specifically, when looking at the region of the polymer dispersion (21) where the inorganic particle is located, the second polymer forming the polymer dispersion (21) may have a form such as a coating layer that thinly covers at least a portion of the side side of the inorganic particle when viewed from the surface of the inorganic particle, specifically with respect to the long axis direction of the inorganic particle. At this time, the second polymer derived from the polymer dispersion (21) that forms the coating layer can suppress the formation of voids caused at the interface between the side side of the inorganic particle and the matrix (10). Specifically, the first polymer forming the matrix (10) and the inorganic particle have low compatibility due to being heterogeneous materials, and there is a concern that separation between heterogeneous materials and the formation of voids may occur when stretching the anisotropic diffusion layer in the manufacturing process described later. However, the second polymer arranged in a form that covers the side side of the inorganic particle can function as a buffer layer (23) that can mitigate the difference in compatibility between the first polymer forming the matrix (10) and the inorganic particle, thereby minimizing or preventing the formation of voids on the side side of the inorganic particle. Here, the side of the inorganic particle refers to an outer surface defined as the right or left side when the two ends along the major axis of the inorganic particle are defined as the upper and lower surfaces, or the front and rear surfaces. Meanwhile, the number of sides and specific shapes of the inorganic particle can be defined according to the shape of the inorganic particle, so the present invention is not specifically limited thereto. For example, assuming the inorganic particle is a cylinder where the major axis is the height, the left and right sides that serve as the sides may be a single continuous curved surface. Additionally, for example, if the inorganic particle is a polyhedron, the number of left and right sides may be two or more, the surface directions may be the same or different from each other, and the shape of each face may be independently a flat or curved surface.

[0071] Meanwhile, the function of the above-described polymer dispersion (21) as a guide and buffer layer may depend on the combination of physical properties between the second polymer forming the polymer dispersion (21) and the first polymer forming the matrix (10).

[0072] Specifically, in order to perform a guide function, the melt viscosity of the first polymer at a predetermined temperature may be different from that of the second polymer. In addition, to facilitate the realization of the morphology of the matrix (10) / polymer dispersion (21) determined by the formability and dispersibility of the polymer dispersion (21) formed by the second polymer within the matrix (10) formed by the first polymer, and at the same time to prevent inorganic particles from moving toward the matrix (10) outside the polymer dispersion (21) and to improve alignment such that the long axis direction of the inorganic particles is aligned with the x-axis direction of the matrix (10), the melt viscosity of either the first polymer or the second polymer may preferably be 1.3 times or more than the melt viscosity of the other polymer, and as another example, may be 1.5 times or more, 1.8 times or more, 2 times or more, or 3 times or more, and as another example, may be 5 times or less, or 4 times or less. Meanwhile, regarding the relative melt viscosity between the first polymer and the second polymer, since the relationship between the relative melt viscosity of the two polymers varies by temperature even when assuming the same two polymers depending on the specific type of polymer, the present invention is not specifically limited thereto.

[0074] In addition, to function as a buffer layer, the second polymer may have a lower glass transition temperature than the first polymer, and / or the second polymer may be amorphous and the first polymer may be crystalline. Specifically, the second polymer having a lower glass transition temperature than the first polymer under stretching temperature conditions may be softer than the first polymer, which may be advantageous for having relatively higher ductility or elasticity. Furthermore, compared to the crystalline first polymer, the amorphous second polymer is less ductile due to crystals, making it advantageous for exhibiting higher ductility than the first polymer. The physical properties of the second polymer compared to the first polymer allow it to act as a buffer when stretching in the TD direction between the inorganic particles and the first polymer in a structure of inorganic particles, the second polymer (polymer dispersion (21)), and the first polymer (matrix (10)) arranged in the same order as stacked in the TD direction, and this may be more advantageous for suppressing the occurrence of voids at the interface between heterogeneous materials. In addition, a large buffer function in the TD direction enables stretching in the TD direction at a large ratio compared to the MD direction, thereby enabling the realization of an anisotropic diffusion layer (100) that is anisotropically diffused in a direction parallel to the x-axis (MD direction), which is the alignment direction of the long axis of the dispersion (20). If the relationship between the glass transition temperatures of the first polymer and the second polymer, and / or the combination of crystal phases, does not satisfy the above-described conditions, voids may occur more frequently on the side of the inorganic particle that is in the TD direction, and as a result, the aspect ratio of the inorganic particle may be relatively reduced structurally, thereby lowering the anisotropic diffusion properties. Furthermore, the difference in refractive index between the matrix (10), the polymer dispersion (21), and / or the inorganic particle forming an interface with the formed voids increases, causing a decrease in brightness and / or a risk that the polymer dispersion (21), inorganic particle, and / or void may be visible to the naked eye.

[0076] Meanwhile, it should be noted that when the combination of crystal structures between the first polymer and the second polymer is semicrystalline or crystalline and amorphous, the glass transition temperature between the first polymer and the second polymer does not necessarily have to be greater for the first polymer than for the second polymer. However, in this case, even if the glass transition temperature of the second polymer is greater, it is preferable that the glass transition temperature of the second polymer be 6°C or less greater than the glass transition temperature of the first polymer. If the glass transition temperature of the second polymer is more than 6°C higher than the glass transition temperature of the first polymer, it may be difficult to prevent the occurrence of voids on the side of the inorganic particle even if the crystal structure conditions of the first polymer and the second polymer described above are satisfied.

[0078] Additionally, at a given temperature, the melt viscosity (Pa·S) of the first polymer and the melt viscosity (Pa·S) of the second polymer may each be independently 100 Pa·S or higher, more preferably 200 Pa·S or higher, and as another example, 2,000 Pa·S or lower. This facilitates the formation of a morphology in which the polymer dispersion (21), which is the second polymer, is formed and dispersed within the matrix (10), which is the first polymer. It may also be advantageous to orient the long axis direction of the inorganic particles (22a) in the x-axis direction, which is the same direction as the long axis direction of the polymer dispersion (21), through a guide of the second polymer extending in a specific direction, specifically the x-axis. If the melt viscosity of either the first polymer or the second polymer is less than 100 Pa·S, it may be difficult to implement a morphology composed of a matrix and a polymer dispersion. In addition, if the melt viscosity of one or more of the first polymer and the second polymer exceeds 2,000 Pa·S, the alignment and alignment uniformity of the inorganic particles may decrease, and the melt dispersion behavior between the two polymers may be difficult to occur, so the designed morphology may not be realized.

[0080] Meanwhile, in the description of the melt viscosity described above, the predetermined temperature refers to any temperature between the temperature at which the first polymer and the second polymer begin to melt and the temperature at which they are completely melted. Specifically, it is a specific temperature within the temperature range between the spinodal and binodal of the first polymer and the second polymer exhibiting UCST behavior during melt blending, and as a specific example, it may be the melt processing temperature.

[0082] Additionally, the first polymer and the second polymer forming the polymer matrix (10) and the polymer dispersion (21) of the anisotropic diffusion layer (100) may be contained in a weight ratio of 6 to 9.8: 4 to 0.2, as in other examples, a weight ratio of 8.0 to 9.8: 2 to 0.2, a weight ratio of 8.5 to 9.8: 1.5 to 0.2, or a weight ratio of 9.0 to 9.8: 1.0 to 0.2. If the second polymer is included in an amount less than 0.02 times the total weight of the first and second polymers, the number of polymer dispersions and cross-sectional diameters within the anisotropic diffusion layer are excessively reduced. Consequently, it may be difficult to exhibit sufficient anisotropic diffusion together with the non-polymer dispersions, and it may be difficult to act as a guide to align the long axis direction of the inorganic particles and as a buffer layer to suppress the occurrence of lateral voids in the inorganic particles. This may lead to a decrease in the alignment of the inorganic particles and an increase in the occurrence of lateral voids in the inorganic particles, which may result in a further decrease in anisotropic diffusion and brightness. Additionally, if the second polymer is included in an amount exceeding 0.4 times the total weight of the first and second polymers, the number of polymer dispersions and cross-sectional diameters may increase, which may make it difficult to achieve sufficient frontal brightness. Furthermore, the randomness of the alignment direction of the inorganic particles dispersed within the polymer dispersions increases, making it difficult to sufficiently improve the alignment of the inorganic particles despite guidance through the polymer dispersions.

[0084] Next, a nonpolymer dispersion (22) containing inorganic particles will be described.

[0085] The above-described nonpolymer dispersion (22) performs the function of exhibiting anisotropic diffusivity together with the above-described polymer dispersion (21). To this end, the above-described nonpolymer dispersion (22) includes inorganic particles, and the inorganic particles may have an average aspect ratio of 3.0 or higher, as another example, 3.5 or higher, 4.0 or higher, or 8.0 or higher, thereby enabling excellent anisotropic diffusivity. If the average aspect ratio of the inorganic particles is less than 3.0, it may be difficult to exhibit anisotropic diffusivity. However, as another example, the inorganic particles may have an average aspect ratio of 15.0 or lower, or 13.0 or lower. In order for the average aspect ratio of inorganic particles to exceed 15.0, inorganic particles with an aspect ratio much larger than 15.0 must be introduced to account for the possibility of inorganic particles breaking during the mixing process prior to melt extrusion. However, as the aspect ratio of the introduced inorganic particles increases, the degree of breaking during the mixing and melt extrusion processes becomes very irregular, making it difficult to exceed the average aspect ratio of 15.0. Furthermore, due to the irregular breaking, the number of inorganic particles with an aspect ratio of less than 3.0 may increase significantly, raising concerns that anisotropic diffusion may be greatly reduced. Here, the average aspect ratio (e / f) of the inorganic particles is the ratio of the average length in the major axis direction (e) to the average diameter (f) of the plane perpendicular to the major axis direction, and the diameter refers to the longest length among the line segments crossing the cross-section perpendicular to the major axis direction.

[0087] In addition, the above-described inorganic particles may have the aspect ratio described above, while having an average length of 3 to 15 μm, which may be advantageous for exhibiting the desired anisotropic diffusivity.

[0088] In addition, the inorganic particles provided in the non-polymer dispersion (22) may include inorganic particles with a length of 2.5 μm or less in an amount of 23% or less, preferably 20% or less, and more preferably 17% or less of the total inorganic particles. Even when the inorganic particles satisfy an average aspect ratio of 3.0 or more and an average length of 3 to 15 μm, if inorganic particles with a length of 2.5 μm or less are included in an amount of 23% or less of the total inorganic particles, it may be advantageous to achieve high anisotropic diffusivity and brightness simultaneously. If inorganic particles with a length of 2.5 μm or less are included in an amount exceeding 23% of the total inorganic particles, anisotropic diffusivity may be reduced, and turbidity may increase, leading to a significant decrease in frontal brightness.

[0090] Meanwhile, in order to control the proportion of particles having an insufficient length in the inorganic particle length distribution, the inorganic particles fed into the manufacturing process may undergo a screening process by filtering them before feeding to remove those that are shorter than (or less than) and / or longer than (or exceed) a specific length. Alternatively, during the melt extrusion process, a filtration unit within the equipment may be configured to remove inorganic particles shorter than a certain length, thereby controlling the extruded anisotropic diffusion layer so that inorganic particles shorter than a certain length are not included. Meanwhile, it should be noted that the method of controlling the exclusion of inorganic particles shorter than a certain length is not limited to this, and known means may be appropriately adopted or modified.

[0092] In addition, the inorganic particles may have an average length of 3 to 15 μm and an average diameter of 0.5 to 2.0 μm, more preferably 0.5 to 1.5 μm, thereby enabling enhanced anisotropic diffusivity. If the average length and average diameter of the inorganic particles fall outside the aforementioned ranges, the improvement in anisotropic diffusivity may be minimal, and as the probability of the inorganic particles being recognized as foreign matter and filtered out increases during the melt extrusion process, there is a concern that the content of inorganic particles in the final product may be reduced compared to the input inorganic particles. Furthermore, if the average diameter of the inorganic particles exceeds 2.0 μm, they may be visible as foreign matter on the surface, and consequently, there is a concern that the visibility of the displayed image may be significantly reduced.

[0094] Additionally, the non-polymer dispersion (22) can be used without limitation in the case of known inorganic particles employed in the optical film. For example, the inorganic particles may contain one or more selected from the group consisting of titanium oxide, zinc oxide, magnesium oxide, strontium carbonate, calcium carbonate, magnesium carbonate, cobalt carbonate, manganese carbonate, calcium silicate, calcium sulfate, aluminum hydroxide, imagolite, silicon carbide, barium sulfate, and silicon oxide, and may include, for example, calcium carbonate and / or barium sulfate.

[0096] In addition, the inorganic particles may have a known shape in which one direction becomes the major axis. For example, the inorganic particles may be needle-shaped, polyhedron-shaped, cylinder-shaped, etc., and the present invention is not specifically limited thereto. For example, the inorganic particles may be needle-shaped in the case of calcium carbonate and plate-shaped in the case of barium sulfate.

[0098] Additionally, as the non-polymer dispersion (22), inorganic particles may be contained in an amount of 0.5 to 10 weight% based on the total weight of the anisotropic diffusion layer (100), or, as another example, 0.5 to 5 weight%, 0.5 to 3 weight%, or 0.5 to 1.5 weight%, thereby maximizing anisotropic diffusion while minimizing the loss of frontal light transmittance. If the inorganic particles are contained in an amount less than 0.5 weight% based on the total weight of the anisotropic diffusion layer, it may be difficult to achieve sufficient anisotropic diffusion, and if they are contained in an amount exceeding 10 weight%, the turbidity increases, which lowers the frontal light transmittance, and thus there is a concern that the brightness of the final product may be lowered. Meanwhile, depending on the shape of the inorganic particles, if both ends in the long axis direction are pointed like needles, a void may be formed extending from both ends of the inorganic particles outward in the long axis direction due to stress at the ends during extrusion and / or stretching. In this case, the non-polymer dispersion can form a single dispersion in the order of a void, an inorganic particle, and a void at the other end along the long axis direction. Since the void at the first end and the void at the other end are located at the ends of the inorganic particle along the long axis direction, this results in a greater aspect ratio of the non-polymer dispersion (22), thereby achieving greater anisotropic diffusion. However, voids formed to extend outward from the ends of the inorganic particle along the long axis direction increase anisotropic diffusion but, conversely, may reduce frontal brightness. Accordingly, when voids formed to extend outward from the ends of the inorganic particle along the long axis direction are provided, the inorganic particle may be included in an amount of 5% or less by weight, or, as another example, 3% or less by weight, or 1.5% or less based on the total weight of the anisotropic diffusion layer (100). By reducing the total volume of voids contained within the anisotropic diffusion layer (100), the reduction in brightness can be minimized.

[0100] According to one embodiment of the present invention, the surface of the inorganic particle may further be provided with a modification layer to suppress the formation of voids on the side surface when the long axis direction of the inorganic particle is considered as the top / bottom, particularly at the interface with the matrix (10). The modification layer may be any known compound that improves the compatibility between the inorganic particle and the first polymer and / or the second polymer, without limitation, and preferably may be modified with a compound represented by the following chemical formula 1 and / or a silane compound, and more preferably may be modified with a compound represented by chemical formula 1 and a silane compound. Specifically, the inorganic particle has poor compatibility with the first polymer / second polymer, which are organic materials of different materials, and there is a risk that voids may exist at the interface between the matrix (10) and / or the polymer dispersion (21) and the inorganic particle during the process of stretching the extruded A-sheet film. In addition, if the inorganic particles have hygroscopic properties, they may generate alkali hydroxides with a pH of 9 or higher through hygroscopic absorption. The generated alkali hydroxides may promote high-temperature hydrolysis of the matrix (10) or polymer dispersion (21) components, thereby inducing gas, and there is a concern that the generation of voids at the interface between the inorganic particles and the matrix (10) or polymer dispersion (21) may increase significantly during this process. However, when the surface of the inorganic particles is modified with a compound represented by Chemical Formula 1 below or a silane-based compound as a modification layer to modify the surface of the inorganic particles, it may be advantageous to increase compatibility at the interface between the matrix / polymer dispersion components and the inorganic particles. In particular, in the case of the compound represented by Chemical Formula 1, it reacts with moisture absorbed before the inorganic particles, thereby reducing the absorption of moisture by the inorganic particles. This prevents high-temperature hydrolysis of the matrix components caused by the products generated by the absorption of moisture by the inorganic particles, and thus prevents the release of gas and the generation of voids.In addition, the compound represented by Chemical Formula 1 reacts with absorbed moisture to produce phosphoric acid and alcohols (R1OH, R2OH, and / or R3OH). The generated phosphoric acid is weakly acidic and can lower the high pH of the alkali hydroxide produced by the reaction of the inorganic particles due to moisture absorption, which can be more advantageous in preventing high-temperature hydrolysis of the matrix components. Furthermore, the generated alcohols (R1OH, R2OH, and / or R3OH) do not induce yellowing in the optical film and do not react with the non-polymer dispersion of inorganic particles, thereby preventing the formation of additional voids due to the products. In other words, if a compound used for surface modification (e.g., a fatty acid) reacts with moisture to generate moisture again, there is a risk of voids being generated through the mechanism described above as the generated moisture is absorbed by the inorganic particles again. Additionally, the generated moisture can cause yellowing, which may degrade the appearance quality and color reproduction of the display.

[0101] [Chemical Formula 1]

[0102]

[0103] R1, R2, and R3 may each independently be hydrogen, or a straight-chain or branched-chain alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and more preferably, R1, R2, and R3 may each independently be a straight-chain or branched-chain alkyl group having 1 to 5 carbon atoms, or an aryl group having 6 to 10 carbon atoms. If the number of carbon atoms exceeds 10, the surface of the inorganic particle may not be easily modified with a material represented by Formula 1.

[0105] In addition, the above-mentioned silane compounds may be used without limitation in the case of compounds that enhance compatibility between inorganic particles and polymer compounds; however, as examples thereof, vinyltrichlorosilane, trimethoxyvinylsilane, triethoxyvinylsilane, vinyltris(methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-(2-aminoethyl-3-aminopropyl)trimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-(methacryloxypropyl)methyldimethoxysilane, 3-(methacryloxypropyl)trimethoxysilane, 3-(methacryloxypropyl)methyldiethoxysilane, 3-(methacryloxypropyl)triethoxysilane, N-β-(amino It may include one or more selected from the group consisting of ethyl)-γ-aminopropylmethyldimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, (3-chloropropyl)trimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPT), and bis[(triethoxysilyl)propyl]disulfide, etc., and more preferably may be an epoxy-silane, which is a silane compound containing an epoxy group, or a vinyl-silane, which is a silane compound containing a vinyl group, and more preferably may be an epoxy-silane, and thereby the method described below The binder properties between the second polymer, which is the buffer layer (23), and the surface of the inorganic particle are improved, so that voids generated during stretching can be prevented or minimized.

[0107] According to one embodiment of the present invention, as shown in FIG. 7, the number of non-polymer dispersions (22) in the anisotropic diffusion layer (100) in which the angle formed by each major axis direction (ℓ1, ℓ2) and the x-axis direction is within ±15° may be 65% or more of the total number of non-polymer dispersions (22) observed, as in other examples, 70% or more, 75% or more, 80% or more, or 85% or more, and this may be advantageous for achieving the desired anisotropic diffusion. If the number of inorganic particles in which the angle (θ) formed by the x-axis direction and the major axis direction (ℓ1, ℓ2) of the inorganic particles is within ±5° is less than 65% of the number of inorganic particles in the non-polymer dispersion (22) observed, it may be insufficient to achieve sufficient anisotropic diffusion.

[0108] Meanwhile, the quantification of inorganic particles in which the angle (θ) formed by the x-axis direction and the long axis direction (ℓ1, ℓ2) of the inorganic particles, which are non-polymer dispersions (22), is within ±15° can be performed by designating five arbitrary points on an optical film specimen with a width and height of 10 cm × 10 cm, observing the surface of the specimen using an optical microscope equipped with a polarizing filter at a magnification of 500x in transmission / reflection mode while adjusting the focus in the thickness direction of the specimen, and in order to quantify the inorganic particles that fall within the angle range, capturing and analyzing the focused observation areas of the inorganic particles (S) to obtain the total number of inorganic particles observed at the five points and the number of inorganic particles in which the angle (θ) formed by the x-axis direction and the long axis direction (ℓ1, ℓ2) of the inorganic particles is within ±15°. In this case, the specimen may be analyzed in the form of an optical film having a skin layer, etc., in addition to the anisotropic diffusion layer, or the anisotropic diffusion layer with the skin layer removed may be analyzed to facilitate observation, and the present invention is not particularly limited thereto.

[0110] In addition, the above-described anisotropic diffusion layer (100) may have a thickness of 150 μm or less, preferably 100 μm or less, 80 μm or less, or 60 μm, and as another example, may be 35 μm or more, or 10 μm or more. If the thickness of the anisotropic diffusion layer exceeds 150 μm, it may be difficult to sufficiently express brightness and anisotropic diffusion properties, and if it is less than 35 μm, it may be difficult to express anisotropic diffusion properties, and the surface quality of the anisotropic diffusion layer may be degraded due to the non-polymer dispersion, which is an inorganic particle.

[0112] Additionally, the optical film (200) may further include a skin layer (110) disposed on at least one surface of the anisotropic diffusion layer (100). The skin layer (110) serves to supplement mechanical strength and protect against external factors. Additionally, preferably, the skin layer (110) may be formed integrally by co-extruding with the optical layer without a separate adhesive layer. As a result, not only can the degradation of optical properties caused by the adhesive layer be prevented, but it is also advantageous for realizing a thinner optical film.

[0113] In addition, the skin layer (110) included in one embodiment of the present invention may be stretched in at least one axial direction after a stretching process is performed following co-extrusion with the anisotropic diffusion layer (100). Through this, the surface hardness is improved compared to the unstretched skin layer, thereby improving scratch resistance and heat resistance.

[0114] The skin layer (110) may be a material of a skin layer commonly used to perform a supporting function of an optical film (200), and preferably polyethylene naphthalate (PEN), copolyethylene naphthalate (co-PEN), polyethylene terephthalate (PET), polycarbonate (PC), polycarbonate (PC) alloy, polystyrene (PS), heat-resistant polystyrene (PS), polymethyl methacrylate (PMMA), polybutylene terephthalate (PBT), polypropylene (PP), polyethylene (PE), acrylonitrile butadiene styrene (ABS), polyurethane (PU), polyimide (PI), polyvinyl chloride (PVC), styrene acrylonitrile mixture (SAN), ethylene vinyl acetate (EVA), polyamide (PA), polyacetal (POM), phenol, epoxy (EP), urea (UF), melanin (MF), unsaturated polyester (UP), silicone (SI), and The cycloolefin polymer can be used alone or in combination, and more preferably, a material identical to the component of the matrix (10) described above can be used.

[0115] In addition, the thickness of the skin layer (110) may be 5 to 30 μm, more preferably 10 to 15 μm, and through this, there is an advantage of minimizing the reduction in brightness through the skin layer (110) and minimizing the change in the wavelength of polarized light caused by a phase difference due to birefringence.

[0117] Additionally, the optical film (200) is placed on the upper part of the LCD panel, and when mounting an upper polarizer equipped with a conventional upper TAC film, the front brightness (N) is set as the blank value. When the upper TAC film of the upper polarizer is changed to an optical film (200) of the same thickness and mounted, it can be implemented to have high anisotropic diffusion properties without significantly reducing the ratio of front brightness (M). In other words, since the anisotropic diffusion properties imparted to the optical film inevitably cause a reduction in front brightness to varying degrees, it is important to exhibit anisotropic diffusion properties while ensuring that the front brightness exhibited when mounted on a commercial TV is at a level sufficient for the product to function adequately. Even if the anisotropic diffusion properties are excellent, it is difficult to commercialize the product if it causes a significant reduction in front brightness. Accordingly, an optical film (200) according to one embodiment of the present invention satisfies a frontal luminance ratio of 80% or more according to the following mathematical formula 1, as in other examples, 81% or more, 82% or more, 83% or more, 85% or more, 86% or more, or 87% or more, while simultaneously having an anisotropic diffusivity of 20% or more according to the following mathematical formula 2, as in other examples, 22% or more, 24% or more, 25% or more, or 26% or more, or as in other examples, 30% or less. If the frontal luminance ratio relative to Blank is less than 80%, the luminance decrease is significant, so even if the anisotropic diffusivity is high, the value as a product that can be mounted on a light source such as a TV may decrease. Furthermore, even if a desirable frontal luminance ratio relative to Blank is achieved, if the anisotropic diffusivity is less than 20%, it may not be desirable in terms of achieving the purpose of the present invention, such as improving the viewing angle when adopted in a display. Meanwhile, it should be noted that although an anisotropic diffusion of more than 30% may be numerically judged to have an excellent viewing angle, an optical film implemented with an anisotropic diffusion of more than 30% is not desirable because it may fail to meet optical physical properties as a product that can be mounted on a light source, such as having high haze and / or low brightness.

[0118] [Mathematical Formula 1]

[0119]

[0120] In mathematical formula 1, N is the frontal luminance (nit) measured after mounting an upper polarizer, which has a conventional TAC film on its upper surface, onto a predetermined panel, and M is the frontal luminance (nit) measured by the same method after mounting an upper polarizer, which has the same configuration as the upper polarizer but has the same thickness as the upper TAC film, onto the same panel, having an optical film to be measured instead of the upper TAC film.

[0122] [Mathematical Formula 2]

[0123]

[0124] Meanwhile, the normal and lateral luminance for the main surface measured in mathematical formulas 1 and 2 may be measured by luminance measurement methods known in the art, and the present invention does not specifically limit the specific method when the normal and lateral directions are measured by the same measurement method.

[0126] The above-described optical film (200), in particular an anisotropic diffusion layer, can be manufactured through melt extrusion among various methods for manufacturing films. Specifically, it can be manufactured by (1) a step of manufacturing a film before stretching by extruding and solidifying inorganic particles, which are a first polymer for forming a matrix (10), a second polymer for forming a polymer dispersion (21) among the dispersions (20), and a non-polymer dispersion (22), through an extrusion unit, and (2) a step of stretching the unstretched film.

[0128] First, as step (1), a step of manufacturing an unoriented film by extruding and solidifying through an extrusion unit is performed.

[0129] (1) The step can be performed using an apparatus and method for manufacturing an unoriented film, specifically 1-1) a step of supplying a first polymer to form a polymer matrix (10), a second polymer to form a polymer dispersion (21) among the dispersions (20), and inorganic particles to form a non-polymer dispersion (22) to an extrusion section. At this time, each of the supplied components may be supplied to a single extrusion section after being mixed, or each component may be supplied individually to independent extrusion sections.

[0130] In addition, the inorganic particles forming the nonpolymer dispersion (22) may be used with their lengths controlled to a predetermined length range prior to mixing so that they can have an appropriate length distribution within the final anisotropic diffusion layer. This prevents an increase in the number of inorganic particles with lengths that are too small, such as 2.5 μm or less, due to breakage during the melt extrusion process, and is advantageous for designing to have a desired length range.

[0132] Preferably, in order to increase the orientation in which the long axis direction of the inorganic particles within the anisotropic diffusion layer (100) is aligned with the x-axis direction within the polymer matrix (10), the inorganic particles may be in a composite chip state mixed with the second polymer before being fed into the extrusion section, and by feeding them into the extrusion section in the composite chip state, the orientation guide of the inorganic particles through the second polymer can be induced. In addition, when supplying the first polymer chip and the composite chip to a single extrusion section, a sufficient stirring process may be performed before supplying them to the extrusion section to induce uniform dispersion, and through this, it may be advantageous to uniformly disperse the dispersed bodies (20) within the anisotropic diffusion layer (100) and to uniformly implement the size in the z-axis direction within the cross-section of the polymer dispersed body (21) in the yz-cross plane of the polymer matrix (10).

[0134] Meanwhile, regarding the dispersion and orientation guide of inorganic particles through the second polymer in the composite chip state, the inorganic particles in the composite chip can be trapped in the second polymer by blocking them from moving toward the first polymer by moving away from the interface between the second polymer and the first polymer due to the difference in melt viscosity between the second polymer and the first polymer in the molten state. Through this, the dispersibility of the inorganic particles within the polymer matrix (10) can be increased, thereby preventing secondary aggregation among the inorganic particles. Additionally, the second polymer within the molten first polymer is separated to form a plurality of polymer dispersions (21), and at least one inorganic particle is disposed in at least some of these polymer dispersions. Each polymer dispersion (21) is extended in the x-axis direction which is the MD direction within the first polymer in a molten state after extrusion. During the process of the polymer dispersion (21) being extended, the inorganic particle trapped within the polymer dispersion (21) is oriented along the polymer dispersion (21) which is extended in length and has a reduced diameter. Therefore, the inorganic particle can be oriented and aligned in the x-axis direction which is the MD direction, in the same direction as the orientation and alignment of the polymer dispersion (21). The polymer dispersion (21) (or the second polymer) acts as a guide for the inorganic particle, and the alignment and alignment uniformity of the inorganic particle can be increased despite the fact that the anisotropic diffusion layer (100) is realized by melt extrusion.

[0136] However, even if the second polymer and the inorganic particles are mixed in a composite chip state and fed into the extrusion section together with the first polymer, the long axis direction of the inorganic particles cannot always be easily aligned in the x-axis direction. That is, as described above, when the melt viscosity of either the second polymer or the first polymer is greater than the melt viscosity of the other polymer, for example, 1.3 times or more, or 1.5 times or more, the inorganic particles in the molten second polymer can have excellent dispersibility within the first polymer and the long axis direction can be easily aligned in the x-axis direction, which is the MD direction in which the second polymer is extruded, and through the stretching process described later, the long axis direction of the inorganic particles can be aligned so that it is closer to the direction in which the polymer dispersion (21), which is the second polymer, is oriented, and the alignment direction of each inorganic particle can be aligned more uniformly. Even if the inorganic particles are introduced in the form of a composite chip mixed with a first polymer forming a polymer matrix rather than a second polymer, or are introduced alone into the extrusion section together with the first polymer and the second polymer without forming a composite chip with the second polymer, and the melt viscosity conditions between the first polymer and the second polymer or the melt viscosity conditions of the preferred polymers are satisfied, and / or the stretching process described below is performed, it may be difficult to achieve dispersibility, orientation, and orientation uniformity of the inorganic particles.

[0138] Meanwhile, as described above, the inorganic particles trapped within the polymer dispersion dispersed inside the first polymer that is melted after extrusion are aligned so that the long axis direction becomes the x-axis direction as the polymer dispersion (21) is extended in the MD direction, which is the x-axis direction. Subsequently, in the stretching process described later, as the length of the polymer dispersion (21) becomes longer and the diameter becomes relatively smaller, the diameter of the polymer dispersion (21) in the part where the inorganic particles are not located may become smaller than the diameter of the inorganic particles. Meanwhile, the fact that inorganic particles are located inside the polymer dispersion (21), or that there is a difference in diameter between the part containing inorganic particles and the part not containing inorganic particles in a single continuous polymer dispersion (21), may be a technical feature that indirectly proves that it is a melt-extruded film.

[0140] In addition, the second polymer, as a buffer layer (23) coated on the surface of the inorganic particle, can function as a buffer to buffer void formation that may occur at the interface between the first polymer forming the polymer matrix and the inorganic particle, and thus can be useful for reducing voids formed toward the long axis reference side of the inorganic particle within the implemented anisotropic diffusion layer (100). Furthermore, the skin layer (110) and the anisotropic diffusion layer (100) can be formed integrally without including an adhesive or adhesive layer between them, and this technical feature may also be a feature that indirectly proves that it is a melt-extruded film.

[0142] In addition, the extrusion section described above may appropriately employ a known method capable of extruding inorganic particles together with a second polymer within a molten first polymer to form a matrix. For example, the molten first polymer and the molten second polymer mixed with inorganic particles may be extruded through different flow paths using a sea-island shaped die designed to match the arrangement of the desired dispersion (20), thereby extruding the second polymer and inorganic particles so as to be precisely dispersed within the molten first polymer. Regarding the manufacturing method using a sea-island shaped die, Korean Registered Patents No. 1264274, No. 1340243, No. 1354271, No. 1201553, No. 1201256, No. 1938892, No. 1938893, No. 1906253, and No. 1940327 by the same applicant as the present application are incorporated by reference, and the present invention omits a detailed description thereof.

[0144] In addition, a skin layer forming component may be introduced into the extrusion unit so that a skin layer (110) disposed on at least one surface of the anisotropic diffusion layer (100) in step (1) is extruded together. For example, the skin layer may be extruded to the upper and / or lower portions of the anisotropic diffusion layer (100) through separate extrusion units to form the skin layer (110), or if a single extrusion unit is used, the melt forming the anisotropic diffusion layer (100) may be flowed to the central region through different flow paths arranged in the thickness direction, and the melt forming the skin layer may be flowed to the upper and lower regions respectively, and then discharged through a T-DIE, thereby forming a three-layer optical film in a single extrusion unit. Whether a single extrusion unit or multiple extrusion units are used, the skin layer that is co-extruded together with the anisotropic diffusion layer has the advantage of being able to form the skin layer within the process of forming the anisotropic diffusion layer without a separate adhesive. Meanwhile, for example, it may be desirable to use a material for the skin layer that is identical to or highly compatible with the first polymer used as the matrix. Additionally, it is desirable to design the thickness of the skin layer to an appropriate thickness to prevent a reduction in brightness due to total internal reflection.

[0146] Next, as step 1-2) of the present invention, a cooling and smoothing step can be performed. As a step of cooling and smoothing the film conveyed from the flow control unit, the film can be cooled and solidified under conditions used in the manufacture of conventional optical films, and then a smoothing step can be adopted and modified. For example, the cooling and smoothing process can be performed on a casting roll. Preferably, one side of the sheet conveyed through the flow control unit is cooled by contacting it with the main cooling roll, and at this time, the temperature of the main cooling roll can be 40°C or lower, more preferably 35°C or lower, or as another example, 20°C or lower. If the temperature of the main cooling roll exceeds 40°C, there is a risk that haze will increase significantly due to the formation of spheroids caused by the crystallization of the first polymer of the matrix or the second polymer of the polymer dispersion, and size differences are likely to be induced between polymer dispersions (21) placed in different regions in the thickness direction of the anisotropic diffusion layer (100). This occurs due to bonding between polymer dispersions dispersed in a molten state, which may cause the size of the solidified polymer dispersion to increase, or the polymer dispersion in the bonded mass to spread out in the left-right direction, that is, along the y-axis of the matrix, thereby reducing the thickness. In addition, the proportion of the matrix modified into a third substance through a chemical reaction at the interface between the polymer dispersion and the matrix may increase, thereby significantly increasing the area percentage of the polymer dispersion. Furthermore, it is more preferable to cool the opposite side that does not come into contact with the cooling roll together using an auxiliary cooling means, and the auxiliary cooling means may be, for example, cooling air, and more preferably, the temperature of the cooling air may be 30°C or lower, and more preferably 20°C or lower.

[0148] Next, as step (2) of the present invention, a step of stretching the cooled and smoothed anisotropic diffusion layer may be performed. The stretching may be performed by employing and modifying the apparatus and process conditions used in optical films, but preferably, in order for the long axis direction of the nonpolymer dispersion (22) to be more easily and uniformly aligned in the x-axis direction of the matrix (10), it may be stretched 2 to 6 times in the x-axis direction which becomes the MD direction and stretched 2 to 6 times in the y-axis direction which becomes the TD direction. If uniaxial stretching is performed only in the x-axis direction, it may be difficult to increase alignment and alignment uniformity of the long axis direction of the nonpolymer dispersion in the x-axis direction of the matrix.

[0149] Meanwhile, in order for anisotropic diffusivity to be expressed in the X-axis direction (or MD direction), which is the alignment direction of the long axis of the dispersed bodies (20), the stretching may be 2 to 8 times in the TD direction and 1 to 2 times in the MD direction.

[0150] In addition, the stretching temperature may be performed at a temperature 10 to 20°C higher than the larger of the glass transition temperatures of the first polymer and the second polymer, respectively. If the stretching is performed at a temperature less than 10°C higher than the larger of the glass transition temperatures of the first polymer and the second polymer, stretching may not occur or may cause fracture. Furthermore, if stretching is performed at a temperature exceeding 20°C higher than the larger of the glass transition temperatures of the first polymer and the second polymer, or if the residence time is excessively long even at an appropriate temperature, the uniformity of stretching may be reduced, and there is a risk that the alignment uniformity of the non-polymer dispersion may also be reduced.

[0152] In addition, the stretched optical film may undergo a heat-setting step. The heat-setting can be performed using a conventional method, and preferably, it can be performed using an IR heater at 180 to 200°C for 0.1 to 3 minutes.

[0154] Referring to FIGS. 5 and 6, an optical film (200) according to one embodiment of the present invention, manufactured through the above-described manufacturing method, can be implemented as a polarizing plate (4000). Specifically, the polarizing plate (4000) is suitable as an upper polarizing plate placed on the light-emitting surface of a liquid crystal panel (5000). Specifically, the polarizing plate (4000) includes an absorption polarizing film (2000) and an optical film (200) placed on the light-emitting surface of the absorption polarizing film (2000). When placed on the light-emitting surface of the absorption polarizer (2100) of the upper polarizing plate, there is an advantage that the contrast ratio improvement effect due to internal light is significant, the viewing angle is increased, and excellent brightness characteristics can be achieved.

[0155] The absorption polarizing film (2000) is a polarizer having an optical function that transmits the first polarization (or the second polarization) and absorbs the second polarization (or the first polarization) among the first polarization and the second polarization having mutually orthogonal planes of vibration, and is provided with a known polarizing layer (2100) having such optical function. The polarizing layer (2100) may be, for example, a substrate film such as polyvinyl alcohol dyed with an iodine-based component or a dichroic dye. Additionally, the iodine-based component, which is one of the dyes dyed on the substrate, may be an iodine-based compound such as iodine and / or potassium iodide. In addition, the above-mentioned dichroic dye can be used without limitation in the case of known dichroic dyes that have high absorbance over a wide range of wavelengths in the direction of the long axis of the molecule and extremely low absorbance in the direction of the short axis, have good affinity for the film that serves as the substrate, can dye even in crystalline regions, are easy to align together when the substrate is stretched, have vivid colors, and have high visual contrast. Therefore, the present invention is not specifically limited to such dyes and a detailed description is omitted.

[0156] The above polarization layer (2100) may have a thickness of, for example, 10 to 200 μm, but is not limited thereto and can be changed according to the purpose.

[0157] Additionally, the absorption polarizing film (2000) may be provided with a protective film (2210) on one or both sides to support and protect the polarizing layer (2100). The protective film (2210) may be used without limitation as a protective film used in conventional absorption polarizing films, and a polymer with excellent transparency, mechanical strength, thermal stability, or moisture barrier properties may be preferably employed. As an example, the protective film (2210) may use an acetate resin such as triacetylcellulose (TAC), a polyester resin, a polyethersulfone resin, a polycarbonate resin, a polyamide resin, a polyimide resin, a polyolefin resin, an acrylic resin, a polynorbornene resin, etc. As an example, the protective film may use a triacetylcellulose (TAC) film considering optical properties. Alternatively, in terms of heat resistance and moisture resistance, it may be a polyester-based film, specifically as an example, a polyethylene terephthalate film. The polyethylene terephthalate film may have a phase difference within the plane of 8,000 nm or more, or 10,000 to 15,000 nm. In addition, the protective film (2210) may have a thickness of 50 to 150 μm, but is not limited thereto. Also, referring to FIG. 6, a protective film such as a TAC film, which is typically placed on top of the polarizing layer (2100), is not provided, and the optical film (200) according to one embodiment of the present invention has the advantage of being able to omit and replace the upper TAC film placed on top of the polarizing layer (2100).

[0159] In addition, the interface between the absorption polarizer (2000) and the optical film (200) described above may be integrally bonded by interposing a separate adhesive layer (not shown). The adhesive layer is used for bonding between optical films and can be implemented using a known adhesive component that does not degrade optical properties. For example, it may be formed as an adhesive in which the adhesive component is used alone, or in combination with at least one water-soluble crosslinking agent of the vinyl alcohol-based polymer, such as boric acid, borax, glutaraldehyde, melamine, or oxalic acid. Additionally, the adhesive may be combined with other additives or catalysts such as acids.

[0161] Additionally, the polarizing plate (4000) may further include a functional layer (3000) on the optical film (200). The functional layer (3000) may be a primer layer, a hard coating layer, an anti-fingerprint layer, an anti-reflection layer, an anti-glare layer, a low-reflection layer, an ultra-low-reflection layer, etc. Additionally, the functional layer (3000) may be implemented by stacking multiple layers to exhibit a composite function. Since the thickness of the functional layer (3000) can be appropriately changed considering the type of functional layer provided and the number of layers, the present invention is not specifically limited thereto.

[0163] In addition, as illustrated in FIG. 6, a polarizing plate (4000) according to one embodiment of the present invention can be implemented as a liquid crystal display device (8000) that is positioned on the light-emitting surface of the polarizing plate (4000) positioned above the liquid crystal panel (5000), that is, adjacent to the viewing side of the liquid crystal display device (8000), opposite to a backlight unit (7000) positioned below the liquid crystal panel (5000).

[0164] Specifically, the liquid crystal display device (8000) can be implemented by arranging in the order of a backlight unit (7000), an absorption polarizing film (2000) as a lower polarizing plate, a liquid crystal panel (5000), a color conversion layer (5300), and a polarizing plate (4000) according to one embodiment of the present invention as an upper polarizing plate.

[0165] The above backlight unit (7000) may be used in a conventional LCD display and may be composed of known components such as a light source, a reflective film, a light guide plate, a light diffusion film, a light collecting film, and a reflective polarizing film.

[0166] Additionally, the liquid crystal panel (5000) includes a liquid crystal layer (5100) and a support plate (5210, 5220) that supports the upper and lower portions of the liquid crystal layer (5100), and may further include known configurations such as electrode lines. Additionally, the liquid crystal panel (5000) may adopt a VA (vertical alignment) mode, an IPS mode, a PVA (patterned vertical alignment) mode, or an S-PVA (super-patterned vertical alignment) mode, but is not limited thereto.

[0168] In addition, an optical film (200) according to one embodiment of the present invention may be disposed on the light-emitting surface of a self-emissive display panel to implement a self-emissive display device. The self-emissive display panel may be a panel employed in known self-emissive displays, such as a plasma display panel (PDP) or an OLED panel, and the present invention is not particularly limited thereto.

[0170] Meanwhile, although the applications of the optical film in this invention have been described using liquid crystal display devices or self-emissive display devices as examples, they are not limited thereto and can be widely used in various known display technologies such as projection displays and field emission displays. Furthermore, in addition to display technologies, it can be widely applied to various light sources such as glass windows and work lighting requiring polarization.

[0172] The present invention will be explained more specifically through the following examples, but the following examples are not intended to limit the scope of the invention and should be interpreted as being for the purpose of aiding understanding of the invention.

[0174] <Example 1>

[0175] Polyethylene terephthalate (PET) was prepared as a first polymer to form a polymer matrix, polycyclohexylene dimethylene terephthalate (PCTG) was prepared as a second polymer to form a polymer dispersion by polymerizing terephthalate and a diol component mixed with ethyl glycol and cyclohexanedimethanol in a 1:2 molar ratio in a 1:1 molar ratio, and calcium carbonate powder was prepared in which inorganic particles having an average length of 25 μm and an average diameter of 1.3 μm, with a length of 5 μm or less, were pre-filtered and removed, and a modified layer of an epoxy-silane compound was formed on the surface.

[0176] Inorganic particles were mixed with the prepared second polymer in a weight ratio of 4:1 and fed into an extruder to produce a composite chip in which the inorganic particles were dispersed in the second polymer. Subsequently, the first polymer chip, the manufactured composite chip, and the first polymer chip for producing the skin layer were fed into the first extrusion unit (220), the second extrusion unit (221), and the third extrusion unit (222) of FIG. 8, respectively. The extrusion temperature of the first polymer chip and the composite chip was set to 260°C, and the polymer flow was corrected so that the melt viscosity ratio became 1.8 by checking the Cap.Rheometer and adjusting the IV. The polymer flow was corrected, and the extrusion process for the skin layer was performed at a temperature level of 260°C. Meanwhile, the prepared first polymer and second polymer had melt viscosities of 180 Pa·S and 100 Pa·S, respectively, and shear rates of 120 sec, respectively, at an extrusion temperature of 260°C in the respective extrusion units described later. -1 , 110 sec -1 The first polymer was a semicrystalline resin with a glass transition temperature of 78°C, and the second polymer was an amorphous resin with a glass transition temperature of 82°C.

[0177] The molten first polymer was transferred to the first pressurizing means (230, Kawasaki gear pump), and the molten second polymer with dispersed inorganic particles was transferred to the second pressurizing means (231, Kawasaki gear pump). The discharge volume of the first pressurizing means and the discharge volume of the second pressurizing means were adjusted so that the content of the non-polymer dispersion in the implemented anisotropic diffusion layer was 1% by weight. Subsequently, a sea-island type composite was manufactured using a sea-island type extrusion die as shown in FIG. 9. Specifically, among the sea-island type extrusion die, the number of sea component layers of the fourth die distribution plate (S4) was 400, the diameter of the die hole of the sea component supply path was 0.17 mm, and the number of sea component supply paths was 25,000 each. The diameter of the discharge port of the sixth die distribution plate was 15 mm × 15 mm. In a feed block with a three-layer structure, a molten first polymer, which will become the skin layer, flowed from the third extrusion section through a channel to form a skin layer on the upper and lower surfaces of the sea-island type composite flow, which forms an anisotropic diffusion layer. The matrix polymer with the formed skin layer was spread in a coat hanger die that corrects the flow velocity and pressure gradient. Specifically, the width of the die inlet was 200 mm and the thickness was 10 mm, the width of the die outlet was 1,260 mm and the thickness was 0.75 mm, and the flow velocity was 1.0 m / min. Subsequently, a cooling and smoothing process was performed in a casting roll, and the material was stretched four times in the MD direction and then three times in the TD direction. Subsequently, heat setting is performed through a heater chamber at 180°C for 2 minutes, so that a skin layer with a matrix thickness of 60 μm and a thickness of 30.25 μm is provided on both sides of the main surface of the anisotropic diffusion layer, with a total thickness of 125 μm, and the major axis directions of the polymer dispersion and non-polymer dispersion, respectively as shown in FIG. 2, are aligned with the x-axis direction of the anisotropic diffusion layer, and the average aspect ratio of the polymer dispersion in the x-axis direction of the anisotropic diffusion layer exceeds 1000, the average aspect ratio of the non-polymer dispersion is 4.3, and the inorganic particles with a length of less than 2.5 μm are 9 of the total inorganic particles.An optical film as shown in Table 1 below was prepared, containing 5%, with a polymer dispersion width of 120 nm and a thickness of 80 nm in the yz cross-section of the anisotropic diffusion layer, a horizontal spacing between adjacent arrays of 190 nm, and a shortest distance spacing between dispersions in the z-axis direction within one array of 55 nm.

[0179] <Examples 2 ~ 3>

[0180] An optical film as shown in Table 1 was prepared by carrying out the same procedure as in Example 1, but with the content of the non-polymer dispersion and / or the particle size of the non-polymer dispersion changed as shown in Table 1 below.

[0182] <Comparative Example 1>

[0183] An optical film as shown in Table 1 was manufactured by carrying out the same procedure as in Example 1, but without including non-polymer dispersions which are inorganic particles as shown in Table 1 below, and by changing the weight ratio of the first polymer and the second polymer, and by omitting stretching in the TD direction during stretching and stretching 6 times in the MD direction. At this time, the width of the polymer dispersions was 170 nm, the average thickness was 75 nm, the horizontal spacing between arrays was 184 nm, and the spacing between polymer dispersions in the z-axis direction within the array was 50 nm.

[0185] <Comparative Example 2>

[0186] An optical film as shown in Table 1 was manufactured by carrying out the same procedure as in Example 1, but without introducing the second polymer-containing composite chip into the first extrusion section, and by introducing the composite chip, in which inorganic particles are combined with the first polymer as shown in Table 1 below, into the first extrusion section alone.

[0188] <Experimental Example>

[0189] The following physical properties were evaluated for optical films according to the examples and comparative examples, and the results are shown in Table 1 below.

[0191] 1. Observation of alignment, size, and void formation of inorganic particles in a non-polymer dispersion

[0192] After selecting five arbitrary points on a specimen measuring 10 cm × 10 cm in width and length, the surface of the specimen was observed and images were captured using an OLYMPUS MX50LT-1273MU optical microscope equipped with a polarizing filter (the magnification of the objective lens was adjusted to 10x, 20x, or 50x, and the magnification of the eyepiece lens was 10x). Then, the length and diameter of the inorganic particles were measured using Image-J, an open program available on the internet, for the images of the five points. Using the inorganic particles measured through the five images as a sample, the average length in the major axis direction (e), the average diameter in the minor axis direction (f), and the average aspect ratio (e / f) of the inorganic particles were calculated.

[0193] In addition, for the void analysis of the optical film, five random points were designated on a specimen measuring 10 cm by 10 cm, and the surface of the specimen was observed by five experts using an OLYMPUS MX50LT-1273MU optical microscope equipped with a polarizing filter. The microscope was set to transmission / reflection mode at a magnification of 500x, and the focus was adjusted in the direction of the specimen thickness to determine whether voids occurred on the side relative to the long axis of the inorganic particles. As a result of the observation, the five experts observed the location of the voids relative to the long axis of the inorganic particles (the end or side of the long axis of the inorganic particles), and marked ○ if voids were formed on the side of the inorganic particles, and × if they were not formed or hardly formed.

[0194] In addition, for the analysis of the alignment direction of inorganic particles, the specimen, equipment, and method used for void analysis were used to adjust the focus in the thickness direction of the specimen at each point, and the parts of the inorganic particles that were in focus during observation were photographed to quantify the inorganic particles that fall within the angle range. Subsequently, through the analysis of the captured photographs, the total number of inorganic particles observed at five points and the inorganic particles whose angle (θ) formed between the x-axis direction and the major axis direction (ℓ1, ℓ2) of the inorganic particles (22) was within ±15° were counted, as shown in FIG. 6, and the percentage of the number of inorganic particles whose angle (θ) formed between the x-axis direction and the major axis direction of the inorganic particles (22) was within ±15° was calculated.

[0196] 2. Evaluation of Optical Characteristics

[0197] Optical characteristics were evaluated using an upper polarizer to which the optical films according to the examples and comparative examples were applied, replacing the upper TAC film of the LCD upper polarizer in the Samsung Electronics Q80A LCD TV, a high-end model on the market. At this time, an upper polarizer to which a conventional upper TAC film of the same thickness as the optical film was applied was used as a control group, and the frontal luminance ratio of each of the examples and comparative examples relative to the control group was defined as the frontal luminance ratio relative to the blank.

[0198] Specifically, a hard coating and a low-refractive index coating were applied to one side of the optical film. The prepared optical film was laminated to the upper surface of an absorption polarizer corresponding to the upper polarizer of the LCD, and a polarizer was manufactured with a TAC (triacetate cellulose) film on the lower surface of the absorption polarizer. After applying the manufactured polarizer as the upper polarizer of the LCD panel of a commercially available Samsung Electronics Q80A LCD TV, the brightness was measured in the front (normal direction, 90° to the main surface of the optical film) and side (30° to the main surface of the optical film) directions.

[0199] In addition, the upper polarizer of the LCD panel of the same LCD TV was fitted with an upper polarizer to which a conventional upper TAC was applied, and the frontal luminance (N) was measured in the same way, and the measured luminance was used as the blank value of the frontal luminance.

[0200] In addition, using the measured values, the frontal luminance ratio relative to Blank was calculated via Equation 1 below, and the anisotropic diffusivity was calculated via Equation 2.

[0201] [Mathematical Formula 1]

[0202]

[0203] In mathematical formula 1, M is the frontal luminance (nit) measured by applying an upper polarizer with an optical film according to an example or comparative example, and N is the frontal luminance (nit) measured by applying an upper polarizer that is a control group.

[0205] [Mathematical Formula 2]

[0206]

[0207] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 matrix Type of first polymer (A) / Melt viscosity (Pa·S) PET / 180 PET / 178 PET / 180 PEN / 1600 PET / 180 polymer dispersion Type of 2nd polymer (B) / Melt viscosity (Pa·S) PCTG / 100 PCTG / 100 PCTG / 100 PC Alloy / 600 Excluded non-polymer dispersion Inorganic particle content (weight%) 1.0 1.0 1.5 Excluded 5.0 Average length (e) / Average minor diameter (f) / Average aspect ratio (e / f) 5.61.34.3 9.8 / 1.2 / 8.1 5.9 / 1.2 / 4.9 5.5 / 1.3 / 4.2 Percentage of specimens with a length of 2.5㎛ or less (%) 9.5 16.3 19.2 8.5 A:B content ratio 9.5:0.4 9.5:0.4 9.25:0.6 6:4 - A / B characteristic combination Crystalline / Amorphous Crystalline / Amorphous Crystalline / Amorphous Crystalline / Amorphous - process Complex chip Second polymer / inorganic particle Second polymer / inorganic particle Second polymer / inorganic particle - First polymer / inorganic particle optical film Percentage of non-polymer dispersions aligned within ±15° in the x-axis direction (%) 95 88 88 - 55 Inorganic particle side void × × × - ○ Frontal Luminance Ratio (%) to Blank 87.8 86.7 82.1 69.9 58.4 Anisotropic diffusivity (%) 27.8 26.3 25.3 22.5 38.5

[0208] As can be seen from Table 1,

[0209] It can be seen that the example has excellent frontal brightness and anisotropic diffusion properties compared to Comparative Example 1, in which a polymer dispersion is positively dispersed without inorganic particles, and Comparative Example 2, in which only inorganic particles are contained without a polymer dispersion.

[0211] Although an embodiment of the present invention has been described above, the concept of the present invention is not limited to the embodiments presented in this specification. Those skilled in the art who understand the concept of the present invention may easily propose other embodiments within the scope of the same concept by adding, changing, deleting, or adding components, and such embodiments shall also be considered to fall within the scope of the concept of the present invention.

Claims

Claim 1 An optical film having an anisotropic diffusion layer comprising: a polymer matrix; and a plurality of dispersions, each having a major axis direction that is the x-axis direction among the x-axis, y-axis, and z-axis mutually perpendicular within the matrix and is positively dispersed in the other two axis directions, and comprising a polymer dispersion and a non-polymer dispersion having an average aspect ratio of 3.0 or more. Claim 2 An optical film according to claim 1, wherein the plurality of dispersed bodies form a plurality of arrays in which two or more dispersed bodies are arranged in a line in the z-axis direction, and each of the plurality of arrays is spaced apart in the y-axis direction and is positively dispersed. Claim 3 An optical film according to claim 2, wherein the y-axis spacing between adjacent arrays is 100 to 500 nm, and the z-axis spacing between adjacent dispersions within one array is 30 to 100 nm. Claim 4 In claim 1, the inorganic particles are an optical film located inside a polymer dispersion. Claim 5 An optical film according to claim 1, wherein the polymer matrix comprises a crystalline or semicrystalline resin, and the polymer dispersion comprises an amorphous resin. Claim 6 The optical film according to claim 1, wherein the inorganic particles have an average length of 3 to 15 μm and an average diameter of 0.5 to 2.0 μm. Claim 7 An optical film according to claim 1, wherein the inorganic particles have an average length of 3 to 15 μm, and inorganic particles with a length of 2.5 μm or less are included in an amount of 17% or less of the total inorganic particles. Claim 8 An optical film according to claim 1, wherein the inorganic particles are contained in an amount of 0.5 to 5 weight percent based on the total weight of the anisotropic diffusion layer. Claim 9 An optical film according to claim 1, wherein a buffer layer derived from a polymer dispersion is interposed at least in part of the interface between the side surface of the inorganic particle in the long axis direction of the inorganic particle and the polymer matrix. Claim 10 An optical film according to claim 1, characterized in that the anisotropic diffusion layer is formed through melt extrusion. Claim 11 An optical film according to claim 1, wherein the matrix and polymer dispersion are included in a weight ratio of 6 to 9.8: 4 to 0.

2. Claim 12 A polarizing plate disposed on a light-emitting surface of a liquid crystal panel, wherein the polarizing plate comprises: an absorption polarizing film; and an optical film according to any one of claims 1 to 11 disposed on a light-emitting surface of the absorption polarizing film. Claim 13 A liquid crystal display device comprising: a liquid crystal panel; and a polarizing plate according to claim 12 disposed on at least the light-emitting surface of the liquid crystal panel. Claim 14 A display device comprising: a self-emissive display panel; and an optical film according to any one of claims 1 to 11 disposed on the light-emitting surface of the self-emissive display panel.

Images