KR20180111327A - Complex polarizing film, method for manufacturing thereof, light source assembly comprising the same, and display comprising the same - Google Patents

Abstract

The present invention relates to a composite polarizing film and, more particularly, to a composite polarizing film, a manufacturing method thereof, and a light source assembly and a liquid crystal display apparatus including the same. According to the present invention, extra parts constituting a module for a display are integrally implemented to reduce the number of parts, to simplify an assembly process, and not to decrease luminance. The composite polarizing film comprises a first polarizing film and a second polarizing film.

Description

TECHNICAL FIELD [0001] The present invention relates to a composite polarizing film, a method of manufacturing the same, a light source assembly including the same, and a liquid crystal display device including the same,

The present invention relates to a composite polarizing film, and more particularly, to a composite polarizing film which can reduce the number of parts and simplify the assembling process by integrating the separate components constituting the display module, A method of manufacturing the same, a light source assembly including the same, and a liquid crystal display device.

Flat panel display technology is mainly composed of liquid crystal display (LCD), projection display, and plasma display (PDP), which have already secured a market in the TV field. In addition, field emission display (FED) and electroluminescence display (ELD) And it is expected to occupy the field according to each characteristic. Liquid crystal displays are currently being used in a wide range of applications such as notebook computers, personal computer monitors, liquid crystal TVs, automobiles, and aircrafts, accounting for 80% of the flat panel market, and booming demand for LCDs worldwide.

Conventional liquid crystal displays place a liquid crystal and an electrode matrix between a pair of light absorbing optical films. In liquid crystal displays, the liquid crystal portion has an optical state that changes accordingly by moving the liquid crystal portion by an electric field generated by applying a voltage to the two electrodes. This process displays an image by using a polarized light in a specific direction as a 'pixel' containing information. For this reason, liquid crystal displays include optical films that induce polarization.

As an optical film for guiding the polarized light, an optical film capable of reusing unintended polarized light as objective polarized light beyond a function of simply separating a desired polarized light has been developed in order to improve utilization efficiency of light emitted from a backlight, One example is a reflective polarizing film.

 1 is a diagram showing an optical principle of a reflective polarizing film. Specifically, P-polarized light from the optical cavity toward the liquid crystal assembly is transmitted through the reflective polarizing film to the liquid crystal assembly. The S-polarized light is reflected from the reflective polarizing film into the optical cavity, Direction is reflected in a randomized state and then transmitted to the reflective polarizing film again, so that the S polarized light is finally converted into P polarized light that can pass through the polarizer of the liquid crystal assembly, passes through the reflective polarizing film, .

In the case of a reflective polarizing film exhibiting the above functions, for example, a multilayered reflective polarizing film in which a flat optical layer having optical anisotropic refractive index and a flat optical layer having optical isotropic refractive index are alternately laminated, a spiral cholesteric film A polymer dispersed type reflective polarizing film including a discontinuous phase having optical anisotropy or optically isotropic refractive index within a continuous phase having optically isotropic or optical anisotropic refractive index, a cholesteric liquid crystal type reflective polarizing film containing a liquid crystal, A sea chart dispersed type reflective polarizing film including a birefringent sea chart, and a wire-grid type reflective polarizing film.

On the other hand, all of the light transmitted through the reflective polarizing film is not polarized in a desired specific direction, and polarized light in some other direction may be mixed. If polarized light in the other direction is directly incident on a display element such as a liquid crystal cell, the polarized light in the other direction can be emitted to the outside of the display panel without influencing the liquid crystal cell controlled to display the image, There may be a problem that the polarization of the other direction emitted together with the emitted light may deteriorate the quality of the displayed image. In order to prevent this, an absorption polarizing film is disposed on one surface of the liquid crystal cell in the direction of the light source device, which is formed of a liquid crystal polymer positioned between the transparent supports arranged up / down.

However, the increase in the number of optical films having different functions provided in implementing the display has a problem of prolonging the time of the display assembly process and lowering the production cost. Further, the air layer existing between the optical films has a problem that optical loss can be caused by forming an optical interface between the film and the air layer.

Korean Patent Publication No. 2011-0053119

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a display device capable of reducing the number of optical films required for parts of a display to facilitate the assembling process, And to provide a composite polarizing film which can be minimized.

It is another object of the present invention to provide a composite polarizing film which can be realized with a thinner thickness and which can be easily adopted in a recent thin display.

Another object of the present invention is to provide a method for producing a composite reflective polarizing film in which light transmission axes are substantially coincident with each other in a more easily manufactured process.

It is another object of the present invention to provide a light source assembly which can increase the light utilization efficiency, reduce the number of parts, and simplify the assembling process by employing the composite polarizing film according to the present invention.

It is another object of the present invention to provide a liquid crystal display device which can simplify the assembly process, have excellent brightness, have a wide viewing angle, and can be realized in a thinner thickness by employing the backlight unit according to the present invention.

According to an aspect of the present invention, there is provided a liquid crystal display comprising: a first polarizing film having a transmission axis in a first direction and a reflection axis in a second direction perpendicular to the first direction; And a second polarizing film disposed adjacent to one surface of the first polarizing film and having an absorption axis in a first direction and a second direction perpendicular to the first direction, .

According to one embodiment of the present invention, the first fiber portion and the second fiber portion may be at least one of different portions of the single-stranded fiber and portions of each of the different fiber strands.

The first polarizing film may further include a skin layer included on at least one surface of the core layer.

The second polarizing film may include a polarizing layer sandwiched between at least one of an iodine component and a dichroic dye and a protective film. The protective film may be provided on the opposite surface of the polarizing layer opposite to the first polarizing film And a protective film may not be provided on one surface of the polarizing layer opposite to the first polarizing film.

Further, a bonding means may be interposed between the first polarizing film and the second polarizing film.

Also, the dispersion is dispersed randomly in the substrate, and the plurality of dispersions may have an aspect ratio of 1/10 to 1/2 based on the vertical cross section in the longitudinal direction, and an average length of the major axis of 0.7 to 1.5 μm .

The refractive index of the base material and the dispersion body may be 0.05 or less in the refractive index difference in any two of the three axes orthogonal to each other and the difference in refractive index in the remaining one axial direction may be 0.1 or more.

In addition, the first polarizing film may be a film stretched in at least one axial direction.

The first polarizing film may further include a skin layer integrally formed on at least one surface of the core layer.

In addition, the long axis lengths of the plurality of dispersion bodies may be 60 to 92% in terms of the dispersion factor with respect to the major axis length according to Equation (1).

[Equation 1]

The ratio of D ₅₀ to D ₁₀ may be 1.6 to 2.4 in the cumulative number distribution of the plurality of dispersoids by the major axis length.

Also, the D ₅₀ may be 0.5 to 0.9 탆.

The D ₁₀ may be 0.3 탆 or more.

In addition, the first direction may be the TD direction, and the second direction may be the MD direction.

The present invention also provides a method of manufacturing a polarizing film comprising the steps of preparing a first polarizing film stretched so as to have a transmission axis in a first direction and having a reflection axis in a second direction perpendicular to the first direction, Preparing a second polarizing film stretched so as to have an absorption axis in a second direction and laminating a second polarizing film on one surface of the first polarizing film to produce a composite polarizing film, to provide.

According to one embodiment of the present invention, the first polarizing film is formed so as to have a reflection axis in the MD direction and a transmission axis in the TD direction, stretched in the MD direction, and then wound on a first roll, Direction and has an absorption axis in the MD direction and a transmission axis in the TD direction, wherein the composite polarizing film is formed by winding the first polarizing film wound on the first roll and conveyed and the transferred second polarizing film through the adhesive means And then rolled to a third roll after being bonded.

In addition, There is provided a light source assembly including a reflective polarizing film according to the present invention.

The present invention also provides a liquid crystal display device including the light source assembly according to the present invention.

The composite polarizing film of the present invention can reduce the number of optical films required for a display part, thereby facilitating the assembly process and minimizing light loss due to the air layer existing between the separated optical films. In addition, it can be realized with a thinner thickness and can be easily adopted for a thinned display. In addition, it is possible to easily produce roll rolls without changing the conventional equipment, and mass production is possible. Furthermore, the composite polarizing film according to an embodiment of the present invention has a better viewing angle, minimizes the phenomenon of visible lines, minimizes light loss due to light leakage, and has superior brightness and excellent polarization characteristics at visible light wavelengths. Accordingly, the composite polarizing film can be widely used as a component of a liquid crystal display device such as a light source assembly, and can be applied to various windows and various polarizing lighting industries.

1 is a schematic view for explaining the principle of a reflective polarizing film,
2 is a cross-sectional view of a composite polarizing film according to an embodiment of the present invention,
3 is a perspective view of a first polarizing film included in an embodiment of the present invention,
4 is a cross-sectional view of a first polarizing film included in an embodiment of the present invention,
5 is a cross-sectional view of a dispersion body included in the first polarizing film included in one embodiment of the present invention,
FIG. 6 is a partially enlarged view of a portion A of FIG. 1;
FIG. 7 is a partially enlarged view of a portion B in FIG. 1;
FIG. 8 is a cross-sectional view of a coat-hanger die, which is a kind of flow control unit used in a manufacturing process of a reflective polarizing film according to an embodiment of the present invention,
Fig. 9 is a side view of Fig. 8,
10 is a schematic view of a manufacturing process of a second polarizing film included in an embodiment of the present invention,
11 is a schematic view of a manufacturing process of a composite polarizing film according to an embodiment of the present invention,
12 is a sectional view of a liquid crystal display device according to an embodiment of the present invention,
13 is an exploded perspective view of a liquid crystal display device according to an embodiment of the present invention,
FIG. 14 is a schematic view of a manufacturing process of a plate-shaped polymer dispersed reflective polarizing film, which is an example of a first polarizing film included in an embodiment of the present invention,
15 is an exploded perspective view of a sea-island extrusion orifice for producing the plate-shaped polymer-dispersed reflective polarizing film of Fig. 14 of the present invention, Fig.
16 is a sectional view of a plate-shaped polymer dispersed reflective polarizing film which is an example of a first polarizing film included in an embodiment of the present invention, and
17 is a cross-sectional SEM photograph of a core layer of a reflective polarizing film according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification. In addition, the present invention is not limited by the size and shape of one configuration shown in the drawings. For example, the number of the plurality of dispersions and their respective sizes shown in FIGS. 2 and 3 are merely examples for explaining the present invention. In the present invention, It is not. In addition, the dotted line shown on one side of Fig. 2 is merely a description of the direction of the long axis of the dispersion, and does not mean the length of the dispersion inside the substrate, which is not shown.

1, a composite polarizing film 1000 according to one embodiment of the present invention includes a first polarizing film 100 and a second polarizing film 200 ).

The first polarizing film (100) is a polarizing film having a transmission axis in a first direction and a reflection axis in a second direction perpendicular to the first direction. The first polarizing film and the second polarizing film, The first polarized light (or the second polarized light) is transmitted and the second polarized light (or the first polarized light) is reflected. For example, the light transmitted through the first polarized light 100 may be P polarized light, It can be polarized.

The first polarizing film 100 may be a known polarizing film that exhibits such a polarizing characteristic, and may be a reflective polarizing film. For example, the reflective polarizing film may be a multilayered reflective polarizing film in which a flat optical layer having optical anisotropic refractive index and a flat optical layer having optical isotropic refractive index are alternately laminated, a cholesteric liquid crystal having spiral cholesteric liquid crystal in a specific direction A polymer dispersed type reflective polarizing film including a discontinuous phase having optical anisotropy or optically isotropic refractive index within a continuous phase having optically isotropic or optical anisotropic refractive index, a birefringent crystal sheet inside the isotropic substrate A sea chart dispersed type reflective polarizing film, and a wire-grid type reflective polarizing film.

However, the multilayer reflective polarizing film may include a layer which is not easy to manufacture, has a high production cost, and can reduce or change optical characteristics such as an adhesive layer. In addition, the cholesteric liquid crystal type reflective polarizing film may further have a separate retardation film for deforming the circularly polarized light into linearly polarized light, which may be unfavorable for a thin display. In addition, the sea chart dispersion type reflective polarizing film has a problem of visible light or bright line. Further, reflective polarizing films of the wire-grid type may have a resolution problem of grid spacing.

Preferably, the first polarizing film 100 may be a polymer-dispersed reflective polarizing film. Specifically, the first polarizing film 100 may be dispersed in the substrate 111 as shown in FIG. 3, The core layer 110 may include a dispersion layer 112 having a refractive index different from that of the dispersion layer 112 in the axial direction of the core layer 110. At least one surface of the core layer 110 may have a skin layer (121, 122).

A birefringence interface may be formed between the base material 111 and the dispersion material 112 contained in the base material. Specifically, the magnitude of the substantial coincidence or discrepancy of refractive index along the spatial X, Y and Z axes between the substrate 111 and the dispersion body 112 affects the degree of scattering of the polarized light along its axis. Generally, the scattering ability changes in proportion to the square of the refractive index mismatch. Thus, the greater the degree of discrepancy in refractive index along a particular axis, the more scattered light rays are polarized along that axis. Conversely, when the inconsistency along a particular axis is small, the polarized light rays along the axis are scattered to a lesser degree. When the refractive index of the substrate is substantially coincident with the refractive index of the dispersion along an axis, the incident light polarized by the electric field parallel to this axis is not scattered regardless of the size, shape and density of the dispersion, something to do. Also, when the refractive index along the axis is substantially coincident, the light rays pass through the object without being substantially scattered. More specifically, the first polarized light (P wave) is transmitted without being influenced by the birefringent interface formed at the interface between the base material 111 and the dispersion body 112, while the second polarized light (S wave) The light is affected by the birefringent interface formed at the interface between the dispersion bodies 112. As a result, the P wave is transmitted and the S wave is modulated by light such as scattering and reflection of light, resulting in separation of polarized light.

Therefore, since the substrate 111 and the dispersion body 112 may form a birefringent interface to cause a light modulation effect, when the substrate 111 is optically isotropic, the dispersion body 112 may have birefringence . On the contrary, when the base material 111 has optical birefringence, the dispersion material 112 may have optical isotropy. Specifically, the refractive index of the x-axis direction of the dispersing element (112) n _X1, the refractive index in the y-axis direction and the n _Y1 and the refractive index of the z-axis direction n _Z1, the refractive index of the substrate (111) n _X2, n _Y2 And n _Z2 , an in-plane birefringence between n _X1 and n _Y1 may occur. More preferably, at least one of X, Y and Z axis refractive indices of the base material 111 and the dispersion body 112 may be different from each other, and more preferably, when the extension axis is the X axis, The difference in refractive index is 0.05 or less, and the difference in refractive index with respect to the X-axis can be 0.1 or more. On the other hand, when the difference in the refractive index is 0.05 or less, it is interpreted as matching.

The base material 111 can be used without limitation in the case of a base material used in a conventional polymer dispersion type reflective polarizing film, and is preferably polyethylene naphthalate (PEN), copolyethylene naphthalate (co-PEN), polyethylene terephthalate (PS), polymethyl methacrylate (PMMA), polybutylene terephthalate (PBT), polypropylene (PS), polypropylene (PP), polyethylene (PE), acrylonitrile butadiene styrene (ABS), polyurethane (PU), polyimide (PI), polyvinyl chloride (PVC), styrene acrylonitrile blend (EVA), polyamide (PA), polyacetal (POM), phenol, epoxy (EP), urea (UF), melanin (MF), unsaturated polyester (UP) For example, a polycarbonate (PC) alloy Lt; / RTI >

The dispersion 120 can be used without limitation in the case of a dispersion material used in a polymer-dispersed reflective polarizing film, and is preferably polyethylene naphthalate (PEN), co-polyethylene naphthalate (co-PEN) (PS), polymethylmethacrylate (PMMA), polybutylene terephthalate (PBT), polybutylene terephthalate (PBT), and polyethylene terephthalate (PET), polycarbonate Polypropylene (PP), polyethylene (PE), acrylonitrile butadiene styrene (ABS), polyurethane (PU), polyimide (PI), polyvinyl chloride (PVC), styrene acrylonitrile blend (EVA), polyamide (PA), polyacetal (POM), phenol, epoxy (EP), urea (UF), melanin (MF), unsaturated polyester (UP) The polymers may be used singly or in combination. For example, PEN.

As shown in FIGS. 3 and 4, the plurality of dispersions 121, 122, and 123 dispersed in the base 110 may have an aspect ratio of 1/10 to 1/2 and an average length of the major axis of 0.7 to 1.5 μm. The aspect ratio means the ratio (b / a) of the length of the short axis (b) to the length of the long axis (a) with reference to the vertical section in the longitudinal direction of the dispersion as shown in FIG. The desired optical properties can be achieved by satisfying the aspect ratio of 1/10 to 1/2 of the dispersion. If the aspect ratio is less than 1/10, the viewing angle having the maximum value of the relative optical gain can be reduced, The desired optical properties such as the viewing angle characteristics may be lowered. In addition, when the aspect ratio exceeds 1/2, the viewing angle can be widened, but as the overall luminance remarkably decreases, there is no meaning of having a wide viewing angle, and it is difficult to commercialize the product as a product, have.

The average length of the long axis (a) may be 0.7 to 1.5 占 퐉. If the average length of the long axis (a) is less than 0.5 占 퐉, The distance between the first polarized light (121, 122, 123) increases and the light incident on the back surface of the reflective polarizing film is not optically modulated and can be transmitted through the upper surface of the reflective polarizing film as it is. The efficiency of light utilization may decrease, ultimately it may not be possible to achieve a high luminance, and it may not be possible to achieve the desired optical characteristics such as light leakage may occur. If the average length of the long axis (a) is more than 1.5 탆, the number of the dispersing bodies 121, 122 and 123 which can be provided in the substrate 110 having a limited thickness can be significantly reduced, It is difficult to achieve the transmittance of the first polarized light and the reflectance of the second polarized light to a desired level in the wavelength range of the visible light, Level optical properties may not be achieved. Further, there is a problem that the viewing angle can be significantly narrowed.

According to a preferred embodiment of the present invention, in order to significantly reduce light leakage and bright line appearance, improve viewing angle, and exhibit excellent polarization characteristics in a visible light ray wavelength range region, 1.5 占 퐉, and the number of dispersion factors with respect to the major axis length according to Equation (1) may be 60 to 92%.

[Equation 1]

The dispersion coefficient (%) with respect to the major axis length according to Equation (1) indicates the degree of spread of each dispersion by the major axis length in a long axis length distribution diagram for a plurality of dispersions. The smaller the number of dispersion factors, Converges to the average length of the long axis, and the longer the length of the long axis of each dispersion means, the wider the spread, without converging to the average length of the long axis. If the dispersion factor of the long axis of the dispersed body included in the reflective polarizing film is less than 60%, there is a possibility that the polarization characteristic in a wavelength band region of the visible light waveband region is lowered. The polarization characteristics degraded in a wavelength range region of the visible light wavelength range ultimately cause unevenness of light transmittance according to wavelengths, which may cause the appearance to be colored with rainbow light or to exhibit a specific one color. In addition, the light diffusion property is lowered and it may be difficult to exhibit an excellent viewing angle.

In addition, if the dispersion factor of the long axis length of the dispersion exceeds 92%, the distribution of the long axis length is varied, thereby facilitating the adjustment of the short axis length of each dispersion, thereby achieving the uniformity of the light transmittance However, it may be difficult to achieve the desired optical characteristics, such as the possibility that the phenomenon of visible light and bright line may become noticeable depending on the case.

On the other hand, in order to more remarkably prevent the phenomenon of light leakage and bright line appearance, the ratio of the dispersion long axis length of D ₅₀ to the dispersion long axis length of D ₁₀ in the distribution in the cumulative number distribution by the dispersion long axis length may be 1.6 to 2.4 .

The meaning of D _X means that the long axis length of the dispersion corresponding to X% of the total dispersion number when the cumulative number distribution curve for the long axis length is plotted from the shortest long axis length to the longest long axis length based on the long axis length it means. For example, when the total number of dispersions is 10, and the lengths of the dispersion long axes are 0.5, 0.6, 0.6, 0.7, 0.7, 0.7, 0.9, 1.0, 1.1, , D ₂₀ is the long axis length of the dispersion corresponding to 20% of the total 10 dispersions, and D ₅₀ means 0.7 μm, which is the long axis length of the dispersion corresponding to 50% of the total 10 dispersions . Ten thousand and one D ₁₀ ratio of the dispersion of the long axis length D ₅₀ of dispersion major axis length of about (D ₅₀ / D ₁₀₎ concerned deteriorate the viewing angle characteristic to decrease in this case 1.6 is less than light leakage, bright line visible symptoms significantly, or light-diffusing function . Also, when D ₅₀ / D ₁₀ exceeds 2.4, there is a possibility that the phenomenon of light leakage and bright line appearance becomes conspicuous or the quality of appearance color may cause a problem.

More preferably, D ₅₀ may be 0.5 to 0.9 탆, D ₁₀ may be 0.3 탆 or more, thereby preventing problems such as light leakage, bright line appearance, appearance color quality, and achieving desired optical properties such as excellent viewing angle Lt; / RTI >

Further, the plurality of dispersions 112a, 112b, and 112c may be elongated and / or arranged so that the major axis direction is substantially parallel to one axis direction of the first polarizing film, more preferably, It is effective to maximize the light modulation effect.

The plurality of dispersions 112a, 112b, and 112c may be randomly dispersed in the substrate 111, thereby enhancing the viewing angle characteristics through light diffusion, It may be more advantageous to exhibit the light modulation effect of light.

Meanwhile, the first polarizing film 100 included in one embodiment of the present invention may further include the skin layers 121 and 122 provided on at least one side of the core layer 110. The skin layers 121 and 112 complement the mechanical strength of the core layer 100. At this time, a separate adhesive layer may be further provided between the core layer 100 and the skin layers 121 and 122. Preferably, the skin layers 121 and 122 are coextruded together with the core layer 100 without a separate adhesive layer Or may be integrally formed. As a result, deterioration of optical properties due to the adhesive layer can be prevented, and more layers can be added to a limited thickness, so that optical properties can be remarkably improved. Further, unlike the conventional case where the core layer is post-adhered to the unstretched skin layer after stretching, the skin layers 121 and 122 included in the embodiment of the present invention are co-extruded simultaneously with the core layer 100, The skin layers 121 and 122 can also be stretched in at least one axial direction. As a result, the surface hardness is improved as compared with the unexposed skin layer, and the scratch resistance is improved and the heat resistance can be improved.

The skin layers 121 and 122 may be materials of a skin layer commonly used for supporting a reflective polarizing film, and preferably include polyethylene naphthalate (PEN), co-polyethylene naphthalate (co-PEN), polyethylene (PS), polymethylmethacrylate (PMMA), polybutylene terephthalate (PBT), poly (ethylene terephthalate), poly (ethylene terephthalate) Polypropylene (PP), polyethylene (PE), acrylonitrile butadiene styrene (ABS), polyurethane (PU), polyimide (PI), polyvinyl chloride (PVC), styrene acrylonitrile blend (EVA), polyamide (PA), polyacetal (POM), phenol, epoxy (EP), urea (UF), melanin (MF), unsaturated polyester (UP) Can be used alone or in combination, and more preferably It may be the same material as the component in the above-described (111).

In the first polarizing film 100 described above, the thickness of the base material 111 may be 20 to 180 탆, and the thickness of the skin layers 121 and 122 may be 50 to 500 탆, but is not limited thereto. In addition, the number of the total dispersions 112 may be 25,000,000 to 80,000,000 when the thickness of the base 111 is 120 占 퐉 based on 32 inch, but is not limited thereto.

Next, a second polarizing film 200 is disposed adjacent to one surface of the first polarizing film 100, the second polarizing film 200 has a transmission axis in the first direction, (Or second polarized light) among the first polarized light and the second polarized light having an oscillating plane perpendicular to each other, and the second polarized light (or the first polarized light) is absorbed by the first polarized light For example, the light transmitted through the second polarizing film 200 may be P polarized light, and the reflected light may be S polarized light.

The second polarizing film 200 may be a known polarizing film that exhibits such a polarizing characteristic and may be an absorbing polarizing film. The absorption polarizing film may include, for example, a polarizing layer 210 dyed with an iodine component or a dichroic dye, and may further include a protective film 221 for protecting the polarizing layer.

The polarizing layer 210 can be a polymer film, and can be used without limitation in the case of a known polymer film used for an absorption polarizing film. For example, the polarizing film 210 can be a polyvinyl alcohol film. The thickness of the substrate may be, for example, 10 to 300 탆, but is not limited thereto and may be changed according to the purpose.

The iodine-based component, which is one of the dyes dyed on the base material, may be an iodine-based compound such as iodine and / or potassium iodide. Further, the dichroic dye has a large absorbance at a wide wavelength in the major axis direction of the molecule, has extremely low absorbance in the minor axis direction, has good affinity to the film as a base material, can dye the crystal region, The known dichroic dyes known to be easily aligned together and having a clear color and a large visual contrast can be used without any limitation so that the present invention is not particularly limited thereto and a detailed description thereof will be omitted.

The protective film 221 can be used without limitation in the case of a protective film used for a conventional absorption polarizing film. The protective film 221 can be used for various purposes such as transparency, mechanical strength, heat stability, And the like can be preferably employed. Examples of the protective film 221 include an acetate resin such as triacetylcellulose (TAC), a polyester resin, a polyether sulfone resin, a polycarbonate resin, a polyamide resin, a polyimide resin, a polyolefin resin A resin, an acrylic resin, a polynorbornene resin, or the like can be used. However, it is most preferably a triacetyl cellulose (TAC) film in consideration of the polarizing property and durability. Also, the thickness of the protective film 221 may be 50-150 탆, but is not limited thereto.

On the other hand, in the case of a conventional absorption reflective polarizing film, it is general to provide a protective film on both sides. However, in the composite polarizing film according to the present invention, since the first polarizing film 100 is integrated with one side of the second polarizing film 200, the second polarizing film 200 polarizing layer 200 integrated with the first polarizing film 100 The protective film may be omitted on the surface of the protective film 210, and the protective film 221 may be provided only on the other surface. The omission of a part of the protective film has the advantage of reducing the thickness of the integrated optical component and reducing the manufacturing cost by omitting the parts.

6, the second polarizing film 200 may further include an adhesive layer 231 for integrating the polarizing layer 210 and the protective film 221. As shown in FIG. The adhesive layer 231 is used for adhesion between the optical films and can use any known adhesive component that does not deteriorate the optical characteristics. The adhesive layer 231 can be formed of a material of the polarizing layer 210 and a material of the protective film 221 It can be selected considering materials. The adhesive layer 231 may be formed of, for example, an adhesive component containing a vinyl alcohol polymer, or a combination of at least one water-soluble crosslinking agent of a vinyl alcohol polymer such as boric acid, borax, glutaraldehyde, melamine, Or may be formed of an adhesive. The adhesive may be blended with other additives or a catalyst such as an acid.

The first polarizing film 100 and the second polarizing film 200 may be further interposed with the bonding means 232 as shown in FIG. The adhesive means may be a pressure-sensitive adhesive, a curable adhesive that is cured through heat, moisture, an electron beam and / or light, a solvent volatile adhesive, and the like, and may be, for example, a pressure-sensitive adhesive. The specific types of the listed adhesives may be those known in the field of optical films.

The adhesive means 232 may have a thickness of 0.01 to 100 탆, but the present invention is not limited thereto.

Meanwhile, the first polarizing film 100 and the second polarizing film 200 described above have a transmission axis in the first direction and a reflection axis / absorption axis in the second direction, wherein the first direction may be the TD direction , And the second direction may be the MD direction. Specifically, in order to minimize the loss of transmitted polarized light, the first polarizing film 100 and the second polarizing film 200 should be laminated so that their transmission axes coincide with each other. If the first polarizing film has the transmission axis in the MD direction and the second polarizing film has the transmission axis in the TD direction, the first polarizing film or the second polarizing film is rotated by 90 占It must be laminated with the second polarizing film or the first polarizing film. Considering that a film usually produced is wound on a roll in the MD direction, rotating one of the polarizing films by 90 DEG means that the two polarizing films wound on the respective rolls can not be laminated in the direction in which they are wound, The polarizing film of the polarizing film is cut by the width of the polarizing film and then rotated by 90 degrees to be lined with the other polarizing film. This leads to complication of the manufacturing process, increase in cost, and prolongation of the manufacturing time.

However, in the composite polarizing film according to the present invention, the directions in which the two polarizing films 100 and 200 wound on the respective rolls are wound in accordance with the transmission axes of the first polarizing film 100 and the second polarizing film 200 are both in the TD direction So that the manufacturing process can be simplified, the manufacturing time can be shortened, and the cost can be reduced.

The composite polarizing film 1000 according to the present invention can be manufactured through the following manufacturing method, but is not limited thereto.

A method of manufacturing a composite polarizing film 1000 according to an embodiment of the present invention includes preparing a first polarizing film 100 having a transmission axis in a first direction and having a reflection axis in a second direction perpendicular to the first direction, Preparing a second polarizing film (200) stretched so as to have an absorption axis in a first direction and a second direction perpendicular to the first direction, and a second polarizing film And laminating the second polarizing film 200 to produce a composite polarizing film.

First, a method of manufacturing each of the first polarizing film 100 and the second polarizing film 200 will be described.

The first polarizing film 100 may be implemented by a manufacturing method described below. However, the manufacturing method described below is only one example, but the present invention is not limited thereto.

First, as step (1), the base component, the dispersion component, and the skin layer component are supplied to the extruder. The base component and the dispersion component may be supplied separately to the extruders, and in this case, the extruder may be composed of two or more. It is also included in the present invention to feed one extruded portion including a separate supply path and a distribution port so that the polymers do not mix. The extruder may be an extruder, which may further include a heating means or the like to convert the supplied polymers in the solid phase into a liquid phase.

The viscosity of the base component is designed to be different from that of the dispersion component so that there is a difference in polymer flow so that the dispersion component can be arranged inside the base component. The following base component and the dispersion component pass through the mixing zone and the mesh filter zone, and the dispersion component is randomly arranged in the base material with a difference in viscosity.

Thereafter, at least one side of the produced core layer is joined with the skin layer component transferred from the extrusion portion. Preferably, the skin layer component may be laminated on both sides of the core layer. When the skin layers are laminated on both sides, the material and the thickness of the skin layer may be the same or different from each other.

Next, the dispersion control unit induces spreading in the flow control unit so that the dispersion component contained in the substrate can be randomly arranged. 8 is a cross-sectional view of a coat-hanger die, which is a kind of preferred flow control part applicable to the present invention, and FIG. 9 is a side view of FIG. 8, The size and arrangement of the cross-sectional areas of the components can be randomly controlled. Specifically, in FIG. 8, since the substrate on which the skin layer transferred through the channel is spread spreads widely from side to side in the coat-hanger die, the dispersion component contained therein also spreads to the left and right.

According to a preferred embodiment of the present invention, there is provided a method of manufacturing a liquid crystal display device, comprising: cooling and smoothing a spread polarized first polarizing film transferred from a flow control unit; stretching a reflective polarizing film through the smoothing step; And thermally fixing the stretched first polarizing film.

First, the step of cooling and smoothing the first polarizing film transferred from the flow control unit may be performed by adopting or appropriately changing the method and conditions used in the production of the first polarizing film, solidifying the same after cooling, Can be smoothed through.

Thereafter, a step of stretching the first polarizing film through the smoothing step is performed. The stretching may be carried out through a conventional first polarizing film stretching process to induce a refractive index difference between the base component and the dispersion component to cause optical modulation phenomenon at the interface, The aspect ratio is further reduced through stretching. For this purpose, the stretching process is preferably capable of performing uniaxial stretching or biaxial stretching, more preferably uniaxial stretching, and still more preferably uniaxially stretching in the MD direction. In addition, uniaxial stretching can be performed in the longitudinal direction of the dispersion. The stretching ratio may be 3 to 12 times. On the other hand, a method of changing an isotropic material to birefringent is commonly known. For example, in the case of stretching under an appropriate temperature condition, the dispersion polymer molecules can be oriented to exhibit birefringence.

Next, the final first polarizing film may be manufactured through a step of heat-setting the stretched first polarizing film. The heat setting can be carried out by suitably employing and changing the conditions of the known method, preferably at 180 to 200 ° C for 0.1 to 3 minutes through an IR heater.

Next, the second polarizing film 200 can be implemented by a manufacturing method described later. The production method described below is a method of producing a second polarizing film in which iodine is dyed on a polyvinyl alcohol base film, but is not limited to a method of manufacturing a second polarizing film 200 included in the present invention .

10, the base film 211 wound from the winding section 400 on which the base film 211 is wound is subjected to a swelling step 410, a dyeing step 420, an orientation step 430, and a drying step The second polarizing film 210 can be manufactured through the second polarizing film 440.

The swelling step 410 allows the polymer molecular chains in the polyvinyl alcohol based film to be more flexible and relax the molecular chains so that the dyes containing the iodine component in the dyeing step 420 are readily incorporated into the polyvinyl alcohol based film Process, and can be carried out by immersing in a swelling tank containing the swelling liquid. The swelling liquid may be pure water or an aqueous solution of boric acid, for example, the temperature of the swelling bath may be from 15 to 50 캜, and may be suitably changed in consideration of the thickness of the base film.

Next, the dyeing step 420 is a step of dipping the base film in a dye containing an iodine component to adsorb the dye in the base film. The iodine-containing dye may be, for example, an iodine aqueous solution, specifically an aqueous solution containing iodine and potassium iodide aqueous solution as a dissolving aid, and the concentration of iodine is approximately 0.01 to 0.8 weight %, Preferably 0.02 to 0.8% by weight, and the use concentration of the potassium iodide may be 0.01 to 10% by weight, more preferably 0.05 to 8% by weight, but is not limited thereto.

The temperature of the dye bath containing dye may be from 20 to 40 캜, preferably from 25 to 35 캜. If the temperature of the dye exceeds 40 캜, wrinkles may be generated in the base film. If the temperature is lower than 20 캜, the PVA molecular chain may not be relaxed effectively and the PVA may not be easily dyed.

On the other hand, the base film that has undergone the dyeing step 420 may be crosslinked before it undergoes the alignment step. The cross-linking treatment may be performed, for example, by treatment with boric acid to immerse the substrate film soaked in an aqueous solution of boric acid, thereby performing color adjustment to prevent water resistance or blue color. On the other hand, in addition to boric acid, a crosslinking agent such as glyoxal or glutaraldehyde can be further used for water resistance by crosslinking. The boric acid aqueous solution may be, for example, an aqueous solution containing about 3 to 19 parts by weight of boric acid and about 1 to 20 parts by weight of iodine based on 100 parts by weight of water. At this time, the temperature may be 50 to 70 ° C, and the treatment time may be 10 to 600 seconds, but is not limited thereto.

Next, an alignment step (430) of the dyed dye is performed. The alignment step is a step of orienting the iodine component, which is a dye to be dyed, in either direction, thereby creating an absorption axis in an oriented direction. The alignment direction can be preferably the MD direction and can have the transmission axis in the TD direction, so that the first polarizing film stretched in the MD direction described above and having the transmission axis in the TD direction can be stuck to the MD direction without rotation There is an advantage. The orientation of the dyed dye can be carried out through stretching of the base substrate film, and the stretching ratio can be from 1: 3 to 8.

Alternatively, the stretching may not be performed in the orientation step 430 and the stretching process is performed together with the swelling step 410 and the dyeing step 420 described above, or before the swelling step 410, ). ≪ / RTI > In addition, the orientation step may be omitted if stretching is performed together at a stage other than the orientation stage, or if it is performed at a separate stage.

The stretching method is not particularly limited, but a wet stretching method and / or a dry stretching method may be used. Examples of the stretching method by the dry stretching method include an inter-roll stretching method, a heated roll stretching method, and a compression stretching method. .

Meanwhile, the washing step may be further performed before or after each step of the swelling step 410, the dyeing step 420, and the orientation step 430 described above. The washing step prior to the swelling step 410 may be a step of removing foreign substances contained in the base film, the washing step after the swelling step 410 may be a step of removing the swelling liquid before the dyeing step, ) May be a step of removing the ultrafiltration dye. The washing solution used in the washing step may be water or a washing solution containing a known additive useful for washing with water and may be carried out by appropriately changing the temperature and time, and is not particularly limited.

Next, the drying step 440 is a step of drying the substrate film to which the oriented dye is adhered. For example, the drying step may be performed in an oven at a temperature of 45 to 70 ° C, but not limited thereto, Can be changed.

In the first polarizing film 100 and the second polarizing film 200 manufactured as described above, the first polarizing film 100 wound on the first roll is wound and transported, and the transported second polarizing film is laminated And a roll-to-roll process in which the composite polarizing film is wound and then wound on a third roll.

Preferably, the second polarizing film simplifies the process in such a manner that the polarizing layer 210 and the protective film 221 are joined together in the process of laminating with the first polarizing film 100 without separately performing a process of laminating the polarizing layer 210 and the protective film 221 can do. Specifically, as shown in Fig. 11, the first polarizing film 100 wound on the first roll 11 and the protective film 221 wound on the second roll 12 are wound and transported, The polarizing layer 210 of the second polarizing film and the upper / lower rollers 21 and 22 may be passed together to be integrated into the composite polarizing film 1000. At this time, an adhesive 31 is injected between the protective film 221 and the polarizing layer 210 and between the first polarizing film 100 and the polarizing layer 210 through the adhesive units 30 and 30 ' It can be laminated. In FIG. 9, the types of adhesives injected through the first adhesive unit 30 and the second adhesive unit 30 'are the same, but they may be different from each other.

The upper and lower rollers 21 and 22 may be subjected to predetermined heat and / or pressure to join the protective film 221, the polarizing layer 210 and the first polarizing film 100, / Or the pressure may be changed in consideration of the kind of the adhesive 31, and the present invention is not particularly limited to this. Further, in the case of a curable adhesive in which the adhesive 31 is cured by light, heat or the like, it is possible to provide a space between the upper and lower rollers 21, 22 and the third roller 13, May further comprise an apparatus of FIG.

Meanwhile, the composite polarizing film 1000 manufactured through the above-described manufacturing process may further include a structured surface layer on at least one side. The structured surface layer functions to control the direction of light incident on the composite polarizing film 1000 or emitted from the composite polarizing film 1000. The structured surface layer can be employed without limitation in a known configuration having a structured surface known to have the function of controlling the direction of light. For example, the structured surface layer may have a cross section of a lenticular, a microlens, a prism shape, Lt; / RTI > Or the irregular irregularities generated by the protrusion of the diffusion particles provided in the binder resin. On the other hand, in the case of including the diffusion particles, since the direction of the light can be controlled through the diffusion particles, the unevenness due to the projection of the diffusion particles is not necessarily accompanied.

The structured surface layer may be provided on the upper part and / or the lower part of the composite polarizing film 1000 via the skin layers 211 and 212 in the composite polarizing film 1000. In this case, the structured surface layer may be integrated with a separate adhesive layer, .

The composite polarizing film 1000 satisfying the physical properties according to the present invention may be used in a light source assembly or a liquid crystal display device including the same to improve the light efficiency and the contrast ratio of the display. The light source assembly can be classified as a direct light source assembly in which the lamp is located at the bottom, an edge light source assembly in which the lamp is located at the side, and the like. The reflective polarizer film according to embodiments of the present invention can be applied to any kind of light source assembly . It is also applicable to a back light assembly disposed below the liquid crystal panel or a front light assembly disposed above the liquid crystal panel. Hereinafter, as an example of various applications, a case is described in which a composite polarizing film is applied to a liquid crystal display device including an edge light source assembly.

12 is a cross-sectional view of a liquid crystal display device according to an exemplary embodiment of the present invention. The liquid crystal display device 2700 includes a backlight unit 2400 and a liquid crystal panel assembly 2500.

The backlight unit 2400 includes a composite polarizing film 2111 for modulating the optical characteristics of light emitted from the light source and then transmitting only the predetermined modulated light. The other components included in the backlight unit and the other components And the reflective polarizing film 2111 may be varied depending on the purpose and are not particularly limited in the present invention.

10, a light source 2410, a light guide plate 2415 for guiding light emitted from the light source 2410, a reflection film 2320 disposed below the light guide plate 2415, And a composite polarizing film 2111 disposed on the upper side of the light guide plate 2415 and disposed in close contact with the lower portion of the first display panel 2511.

At this time, the light sources 2410 are disposed on both sides of the light guide plate 2415. The light source 2410 may be a light emitting diode (LED), a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), or an external electro fluorescent lamp (EEFL). In another embodiment, the light source 2410 may be disposed only on one side of the light guide plate 2415. [

The light guide plate 2415 moves the light emitted from the light source 2410 through total internal reflection, and emits the light upward through a scattering pattern or the like formed on the lower surface of the light guide plate 2415. A reflective film 2420 is disposed under the light guide plate 2415 to reflect the light emitted downward from the light guide plate 2415 upward.

A composite polarizing film 2111 is disposed on the upper side of the light guide plate 2415. The light emitted upward through the light guide plate is incident on the first polarizing film of the composite polarizing film 2111, and the first polarized light (e.g., P polarized light) parallel to the transmission axis separated from the first polarizing film is transmitted through the first polarizing film (E.g., S polarized light) perpendicular to the transmission axis separated from the first polarizing film and parallel to the reflection axis is incident on the second polarizing film and transmitted through the second polarizing film, Polarized film and then reflected by the lower scattering pattern or the reflective film 2320 through the light guide plate 2415 and incident on the first polarizing film. On the other hand, among the light incident on the first polarizing film, a part of the second polarizing light can transmit the first polarizing film, and the second polarized light transmitted and emitted is incident on the second polarizing film, .

On the other hand, other optical sheets may be disposed above or below the composite polarizing film 2111. For example, an optical film capable of controlling the direction of light such as condensing light or diffusing light, a retardation film for changing the phase of light, and / or a protective film or a supporting film can be further disposed. At this time, the optical film for controlling the direction of the light will be effective when the composite polarizing film does not have a structured surface layer separately as described above.

The light source 2410, the light guide plate 2415, the reflection film 2420 and the composite polarizing film 2111 can be received by the bottom chassis 2440.

The liquid crystal panel assembly 2500 includes a first display panel 2511, a second display panel 2512 and a liquid crystal layer (not shown) interposed therebetween. The liquid crystal panel assembly 2500 includes a polarizing plate And a separate polarizing plate may be omitted on the lower surface of the first display panel 2511 due to the second polarizing film of the composite polarizing film 2111.

The liquid crystal display device 2700 may further include a top chassis 2600 covering the edges of the liquid crystal panel assembly 2500 and surrounding the sides of the liquid crystal panel assembly 2500 and the backlight unit 2400.

13 is an example of a liquid crystal display device employing a reflective polarizing film according to a preferred embodiment of the present invention. A reflective plate 3280 is inserted on a frame 3270, and the upper surface of the reflective plate 3280 A cold cathode fluorescent lamp 3290 is placed. An optical film 3320 is disposed on the upper surface of the cold cathode fluorescent lamp 3290 and the optical film 3320 is stacked in order of a diffusion plate 3321, a prism film 3322, and a composite polarizing film 3323 However, the constitution of the optical film and the order of lamination between the respective constituents may be varied depending on the object, and some of the constituent elements may be omitted or plurally, and a different kind of optical film May be further included. On the other hand, the liquid crystal display panel 3310 may be positioned on the upper surface of the optical film 3320 by being inserted into the mold frame 3300.

The light emitted from the cold cathode fluorescent lamp 3290 reaches the diffuser plate 3321 of the optical film 3320. The light transmitted through the diffuser plate 3321 passes through the prism film 3322, is condensed in the traveling direction of the light, passes through the first polarizing film of the composite polarizing film 3323, and is optically modulated . Specifically, the P wave transmits the reflection polarizing film without loss, but in the case of the S wave, light modulation (reflection, scattering, refraction, etc.) occurs and is reflected by the reflection plate 3280, which is the back surface of the cold cathode fluorescent lamp 3290, The properties of the light are randomly changed into a P wave or an S wave, and then pass through the reflective polarizing film 3322 again. The polarized light transmitted through the first polarizing film reaches the liquid crystal display panel 3310 after passing through the second polarizing film. Meanwhile, the cold cathode fluorescent lamp 3290 may be replaced with an LED.

In the present invention, the use of the reflective polarizing film has been described mainly with respect to a liquid crystal display, but the present invention is not limited thereto, and can be widely used in flat panel display technologies such as a projection display, a plasma display, a field emission display and an electroluminescence display, , Glass windows, and working lights that require polarized light.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

100: first polarizing film 110: core layer
121, 122 Skin layer 200 Second polarizing film
210: polarizing layer 221: protective film
231: Adhesive layer 232: Adhesion means
1000: composite polarizing film

Claims (18)

A first polarizing film having a transmission axis in a first direction and a reflection axis in a second direction perpendicular to the first direction; And
And a second polarizing film disposed adjacent to one surface of the first polarizing film and having an absorption axis in a first direction and a second direction perpendicular to the first direction. The method according to claim 1,
Wherein the first polarizing film is dispersed in the base material and has a core layer containing a dispersion having a refractive index different from that of the base material in at least one axial direction. 3. The method of claim 2,
Wherein the first polarizing film further comprises a skin layer contained on at least one side of the core layer. The method according to claim 1,
Wherein the second polarizing film has a polarizing layer and a protective film dyed with at least one of an iodine component and a dichroic dye,
Wherein the protective film is provided on a surface opposite to the one surface of the polarizing layer facing the first polarizing film and the protective film is not provided on one surface of the polarizing layer facing the first polarizing film. The method according to claim 1,
Wherein a bonding means is interposed between the first polarizing film and the second polarizing film. 3. The method of claim 2,
Wherein the dispersion body is randomly dispersed in the substrate, the plurality of dispersion bodies have an aspect ratio of 1/10 to 1/2 based on a vertical cross section in the longitudinal direction, and an average length of the long axis is 0.7 to 1.5 占 퐉. 3. The method of claim 2,
Wherein the refractive indexes of the base material and the dispersion body are 0.05 or less in the refractive index difference in any two of the three axes orthogonal to each other and the difference in refractive index in the remaining one axial direction is 0.1 or more. The method according to claim 1,
Wherein the first polarizing film is a film stretched in at least one axial direction. 3. The method of claim 2,
Wherein the first polarizing film further comprises a skin layer integrally formed on at least one surface of the core layer. The method of claim 6, wherein
Wherein the plurality of dispersoids have a major axis length of 60 to 92% with respect to a major axis length according to the following formula (1).
[Equation 1]

11. The method of claim 10,
Wherein the ratio of the dispersion long axis length of D ₅₀ to the dispersion long axis length of D ₁₀ is 1.6 to 2.4 in the cumulative number distribution of the plurality of dispersoids by the major axis length. 12. The method of claim 11,
Wherein the D ₅₀ is 0.5 to 0.9 탆. 12. The method of claim 11,
Wherein D ₁₀ is 0.3 탆 or more. The method according to claim 1,
Wherein the first direction is the TD direction and the second direction is the MD direction. Preparing a first polarizing film stretched so as to have a transmission axis in a first direction and a reflection axis in a second direction perpendicular to the first direction;
Preparing a second polarizing film stretched so as to have an absorption axis in a first direction and a second direction perpendicular to the first direction; And
And laminating a second polarizing film on one surface of the first polarizing film to produce a composite polarizing film. 16. The method of claim 15,
The first polarizing film is stretched in the MD direction so as to have a reflection axis in the MD direction and has a transmission axis in the TD direction and is wound on a first roll. The second polarizing film is stretched in the MD direction, And has a transmission axis in the TD direction,
The composite polarizing film is produced by a roll-to-roll process in which a first polarizing film wound and unwound from a first roll and a second polarizing film transferred are bonded to each other via an adhesive means and then wound on a third roll Wherein the composite polarizing film is produced by a method comprising: A light source assembly comprising a composite polarizing film according to any one of claims 1 to 14. A liquid crystal display comprising the light source assembly according to claim 17.

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