Optical display device

Abstract

There is provided an optical display device including an optical display device panel and a polarizing plate stacked on the optical display device panel, in which the polarizing plate includes a polarizer and a retardation film laminate sandwiched between the optical display device panel and the polarizer, the light absorption axis of the polarizer is inclined at an angle of 40 DEG to 50 DEG or 130 DEG to 140 DEG with respect to the longitudinal direction of the optical display device panel, and the retardation film laminate has an in-plane retardation of 140 nm to 200 nm and a biaxial degree of greater than 0.5 to less than 1.0 at a wavelength of 550 nm. The earth axis of the retardation film laminate is inclined at an angle of + 15 DEG to + 30 DEG or-30 DEG to-15 DEG with respect to the light absorption axis of the polarizer.

Description

Technical Field

[0001] The invention relates to an optical display device. Background Art

[0002] Organic light emitting diode (OLED) displays may suffer from degradation of visibility and contrast due to reflection of external light. To solve this problem, a polarizing plate including a polarizer and a retardation film may be used. The polarizing plate may provide an antireflection function by preventing the reflected external light from leaking out.

[0003] An organic light emitting diode display can be manufactured by stacking a polarizing plate on an organic light emitting diode panel including a light emitting layer. Since the polarizing plate includes a polarizer having a polarization function, the optical display device may suffer from a blackout phenomenon in which the screen is invisible when viewed with the naked eye through contrast polarized sunglass. Even in this case, it is desirable to reduce the reflective color value and reflectivity over the entire viewing angle range. Recently, as the light emitting layer is formed in various structures, the pentile matrix referring to the arrangement of red, green, blue (RGB) pixels has been diversified into a symmetrical structure or an asymmetrical structure.

[0004] For an optical display panel including a corrugated tile matrix of a symmetrical structure or an asymmetrical structure, it is desirable to reduce reflection color and reflectivity over the entire viewing angle range even when the screen is viewed through polarized sunglasses.

[0005] The background art of the present invention is disclosed in Korean Patent Publication No. 2013-0103595 and the like. Summary of the invention

[0006] Technical issues

[0007] An object of the present invention is to provide an optical display device that prevents the phenomenon that the screen of the optical display device is made invisible (black out) when viewed in the horizontal direction or vertical direction through polarized sunglasses, while achieving low reflection color values ​​and reflectivity over the entire viewing angle range.

[0008] Technical Solution

[0009] One embodiment of the present invention relates to an optical display device.

[0010] 1. The optical display device comprises an optical display panel and a polarizing plate stacked on the optical display panel, wherein the polarizing plate comprises a polarizer and a retardation film laminate sandwiched between the optical display panel and the polarizer, wherein the light absorption axis of the polarizer is inclined at an angle of 40° to 50° or 130° to 140° relative to the long side direction of the optical display panel; and the retardation film laminate has an in-plane retardation (Re) of 140 nm to 200 nm and a degree of biaxiality (NZ) of greater than 0.5 to less than 1.0 at a wavelength of 550 nm, and the slow axis of the retardation film laminate is inclined at an angle of +15° to +30° or -30° to -15° relative to the light absorption axis of the polarizer.

[0011] 2. In 1, the optical display panel may have a corrugated tile matrix, and the corrugated tile matrix has a symmetrical structure or an asymmetrical structure.

[0012] 3. In 1 to 2, the light absorption axis of the polarizer may be inclined at an angle of 45° or 135° with respect to the long side direction of the optical display panel.

[0013] 4. In 1 to 3, the retardation film stack may include a positive C layer.

[0014] 5. In 1 to 4, the positive C layer is placed at a position of the retardation film stack closest to the polarizer.

[0015] 6. In 1 to 5, the retardation film laminate may include a film or a coating layer including a polymer having positive intrinsic birefringence.

[0016] 7. In 1 to 6, the polymer having positive intrinsic birefringence may be present as a main component in the retardation film laminate.

[0017] 8. In 1 to 7, the polymer having positive intrinsic birefringence may include a cycloolefin polymer or a cycloolefin copolymer.

[0018] 9. In 1 to 8, the retardation film stack may include a first retardation layer and a second retardation layer, and the first retardation layer and the second retardation layer satisfy equation 2:

[0019] [Equation 2]

[0020] The in-plane retardation of the first retardation layer at a wavelength of 550 nanometers is less than the in-plane retardation of the second retardation layer at a wavelength of 550 nanometers.

[0021] 10. In 1 to 9, the first retardation layer may have an in-plane retardation of 80 nm to 145 nm at a wavelength of 550 nm, and the second retardation layer may have an in-plane retardation of 180 nm to 250 nm at a wavelength of 550 nm.

[0022] 11. In 1 to 10, the second retardation layer may include a film or a coating containing a polymer having positive intrinsic birefringence.

[0023] 12. In 1 to 11, the second retardation layer may have a thickness greater than that of the first retardation layer.

[0024] 13. In 1 to 12, each of the first retardation layer and the second retardation layer may exhibit positive wavelength dispersion.

[0025] 14. In 1 to 13, each of the first retardation layer and the second retardation layer may be a non-liquid crystal layer.

[0026] 15. In 1 to 14, the first retardation layer and the second retardation layer may be stacked sequentially from the polarizer in the stated order.

[0027] 16. In 1 to 15, the positive C layer may include at least one selected from cellulose-based compounds and polystyrene-based compounds.

[0028] 17. In 1 to 16, the first retardation layer may include at least one selected from cellulose-based compounds and polystyrene-based compounds.

[0029] 18. In 1 to 17, the slow axis of the stacked body formed by the first retardation layer and the second retardation layer may be inclined at an angle of +15° to +30° or -30° to -15° with respect to the light absorption axis of the polarizer.

[0030] Beneficial Effects

[0031] The present invention provides an optical display device that prevents a black screen phenomenon that makes the screen of the optical display device invisible when viewed in a horizontal direction or a vertical direction through polarized sunglasses, while achieving a low reflection color value and a low reflectivity in the entire viewing angle range. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a cross-sectional view of an optical display device according to an embodiment of the present invention.

[0033] Figure 2 is a conceptual plan view of one embodiment of an optical display panel including a corrugated tile matrix having a symmetrical structure.

[0034] Figure 3 is a conceptual plan view of one embodiment of an optical display panel including a corrugated tile matrix having an asymmetric structure.

[0035] Figure 4 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention.

[0036] Figure 5 1 is a graph showing changes in the reflection color value a* and the reflection color value b* of the module of Example 1 with respect to external light according to the viewing angle.

[0037] Figure 6 1 is a graph showing changes in the reflection color value a* and the reflection color value b* of the module of Example 3 with respect to external light according to the viewing angle.

[0038] Figure 7 Graphs showing changes in the reflection color value a* and the reflection color value b* of the module of Comparative Example 4 with respect to external light according to the viewing angle.

[0039] Figures 5 to 7 CIE a*b* values ​​of color changes according to azimuth angles (particularly, 8 degrees, 30 degrees, 45 degrees, and 60 degrees) are shown. DETAILED DESCRIPTION

[0040] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood that the disclosure herein can be implemented in different ways and is not limited to the following embodiments. Herein, the following embodiments are provided so that the disclosure herein will be thorough and complete, and so that the concept of the present invention can be fully conveyed to those skilled in the art. Although the length, thickness or width of various components may be exaggerated in the drawings used for the description of the present invention to illustrate the components of each device, the present invention is not limited thereto. Herein, in all the drawings, the same components will be represented by the same reference numerals.

[0041] The terms used herein are used to describe exemplary embodiments and are not intended to limit the scope of the present invention.Herein, unless the context clearly indicates otherwise, the singular forms "a / an" and "the" are intended to include plural forms as well.

[0042] In this document, spatially relative terms such as "upper" and "lower" are defined with reference to the accompanying drawings. Therefore, it should be understood that "upper surface" can be used interchangeably with "lower surface", and when an element is referred to as being placed "on" another element, the element can be placed directly on the other element, or there can be intervening elements. When an element is referred to as being placed "directly" on another element, there are no intervening elements between the element and the other element.

[0043] In this article, "in-plane retardation (Re)", "out-of-plane retardation (Rth)" and "biaxiality (NZ)" are represented by equation A, equation B and equation C, respectively:

[0044] [Formula A]

[0045] Re=(nx-ny)×d

[0046] [Formula B]

[0047] Rth=((nx+ny) / 2-nz)×d

[0048] [Formula C]

[0049] NZ=(nx-nz) / (nx-ny)

[0050] wherein nx, ny and nz are the refractive indices of the optical device in its slow axis direction, fast axis direction and thickness direction at the measuring wavelength, respectively, and d represents the thickness of the optical device (unit: nanometer).

[0051] In Formulas A to C, the “optical device” may refer to a positive C layer, a first retardation layer, a second retardation layer, or a stacked body formed of the positive C layer, the first retardation layer, and the second retardation layer. In Formulas A to C, the measurement wavelength may refer to a wavelength of 450 nm, 550 nm, or 650 nm.

[0052] Herein, "(meth)acrylic group" refers to acrylic group and / or methacrylic group.

[0053] “X to Y” used herein to express a specific numerical range means “greater than or equal to X and less than or equal to Y (X≤ and ≤Y)”.

[0054] The inventor of the present invention provides an optical display device, which prevents the black screen phenomenon that makes the screen of the optical display device invisible when viewed in the horizontal direction or the vertical direction through polarized sunglasses, while achieving low reflection color values ​​and low reflectivity over the entire viewing angle range. Even for a panel having RGB pixels as a corrugated tile matrix with a symmetrical structure or an asymmetrical structure, the optical display device according to one embodiment of the present invention can achieve the above effect. Specifically, the optical display device according to an embodiment of the present invention provides a much lower reflection color value and reflectivity than an optical display provided with a polarizing plate including a single retardation film (also referred to as a single-sheet type) over the entire viewing angle range.

[0055] Low reflective color values ​​mean that both the reflective color values ​​a* and b* measured when observing the screen of the optical display device are low. The reflective color values ​​"a*" and "b*" refer to the a* value and b* value in the International Commission on Illumination (Commission Internationale de l'Eclairage, CIE) coordinate system, respectively. The reflective color values ​​a* and b* can be obtained from the CIE coordinate system, in which the x-axis representing the a value is orthogonal to the y-axis representing the b value. The a* value becomes red as the absolute value increases in the positive direction and becomes green as the absolute value increases in the negative direction, while the b* value becomes yellow as the absolute value increases in the positive direction and becomes blue as the absolute value increases in the negative direction. The reflective color values ​​a* and b* can be evaluated according to the CIE L*a*b* color coordinate standard.

[0056] The reflection color values ​​a* and b* can be measured using a reflection color value measuring device (DMS803, Instrument Systems Inc. (Konica Minolta Group)) by emitting light from the outside toward a polarizing plate stacked on the optical display panel when the optical display panel (e.g., OLED mobile phone panel) is closed. The optical display device according to the embodiment can have reflection color values ​​a* and b* in the entire viewing angle range: -2≤reflection color value a*≤2 and -2≤reflection color value b*≤2. Within this range, when the screen of the optical display device is observed, the optical display device can reduce color unbalance of the screen in the entire viewing angle range.

[0057] According to one embodiment of the present invention, an optical display device includes an optical display panel and a polarizing plate stacked on the optical display panel, the polarizing plate includes a polarizer and a delay film stack sandwiched between the optical display panel and the polarizer, wherein the light absorption axis of the polarizer is inclined at an angle of 40° to 50° or 130° to 140° relative to the long side direction of the optical display panel; and the delay film stack has an in-plane delay (Re) of 140 nanometers to 200 nanometers and a biaxiality (NZ) of greater than 0.5 to less than 1.0 at a wavelength of 550 nanometers, and the slow axis of the delay film stack is inclined at an angle of +15° to +30° or -30° to -15° relative to the light absorption axis of the polarizer.

[0058] Hereinafter, an optical display device according to an embodiment of the present invention will be explained in detail.

[0059] The optical display panel is composed of a long side direction and a short side length direction. The light absorption axis of the polarizer is tilted at an angle of 40° to 50° or 130° to 140° relative to the long side direction of the optical display panel. Within this range, when the screen is viewed through polarized sunglasses, the optical display device can prevent the black screen phenomenon. When the polarizing plate is combined or attached to the optical display panel so that the light absorption axis of the polarizer substantially the same as the machine direction (MD) of the polarizing plate is tilted at an angle within the above range relative to the long side direction of the optical display panel, the optical display device can achieve this effect. For example, the light absorption axis of the polarizer may be tilted at an angle of 40°, 41°, 42°, 43°, 44°, 45°, 46°, 47°, 48°, 49°, 50°, 130°, 131°, 132°, 133°, 134°, 135°, 136°, 137°, 138°, 139°, 140°, or between 45° and 135° relative to the long side direction of the optical display panel.

[0060] In order to provide low reflection color value and low reflectivity in the entire viewing angle range when the light absorption axis of the polarizer is tilted at an angle of 40° to 50° or 130° to 140° relative to the long side direction of the optical display panel, the retardation film laminate has (i) an in-plane retardation (Re) of 140 nm to 200 nm at a wavelength of 550 nm, (ii) a biaxiality (NZ) of greater than 0.5 to less than 1.0 at a wavelength of 550 nm, and (iii) a slow axis tilted at an angle of +15° to +30° or -30° to -15° relative to the light absorption axis of the polarizer at a wavelength of 550 nm. If any of (i), (ii) and (iii) is not satisfied, the optical display device may not achieve all the effects of the present invention.

[0061] Assuming that the polarizing plate is bonded or adhered to the optical display panel so that the light absorption axis of the polarizer is tilted at an angle of 40° to 50° or 130° to 140°, (i), (ii) and (iii) can be achieved by controlling the in-plane retardation of each of the retardation layers in the retardation film stack at a wavelength of 550 nanometers and the inclination angle of the slow axis of each of the retardation layers relative to the light absorption axis of the polarizer at a wavelength of 550 nanometers.

[0062] The in-plane retardation and biaxiality of the retardation film stack can be measured by a typical retardation measurement device. The slow axis of the retardation film stack can be measured using an AxoScan. The in-plane retardation, biaxiality and slow axis of the retardation film stack are measured by transmitting light in the normal direction relative to its in-plane direction.

[0063] The optical display device may be a light emitting diode display including an organic or inorganic light emitting diode. Here, the light emitting diode may refer to a light emitting diode (LED), an organic light emitting diode (OLED), a quantum dot light emitting diode (QLED), and a light emitting element containing a fluorescent material (such as a phosphor, etc.).

[0064] Reference Figure 1 The optical display device comprises an optical display panel (100) and a polarizing plate (200) stacked on the optical display panel (100).

[0065] Hereinafter, each of the components of the optical display apparatus according to an embodiment of the present invention will be explained in detail.

[0066] Optical display panel

[0067] The optical display panel may be a panel including a light emitting device as a light emitting layer. For example, the optical display panel may include a light emitting layer having a plurality of sub-pixels. The sub-pixels may be individual units that each emit light, and a light emitting diode may be disposed in each of the sub-pixels.

[0068] The plurality of sub-pixels may include a first sub-pixel, a second sub-pixel, and a third sub-pixel that emit light of different colors. For example, the first sub-pixel may be a blue sub-pixel, the second sub-pixel may be a green sub-pixel, and the third sub-pixel may be a red sub-pixel. The plurality of sub-pixels may be arranged in a wave-tile structure. For example, a plurality of first sub-pixels and a plurality of second sub-pixels may be alternately arranged in the same row or in the same column. For example, the first sub-pixel and the third sub-pixel may be alternately arranged in the same row and may be alternately arranged in the same column. A plurality of second sub-pixels may be arranged in a row different from the plurality of first sub-pixels and the plurality of third sub-pixels and in a different column. For example, a plurality of second sub-pixels may be arranged in a column, and a plurality of first sub-pixels may alternate with a plurality of third sub-pixels in another column adjacent to the column. A plurality of second sub-pixels may be arranged in a row, and a plurality of first sub-pixels may alternate with a plurality of third sub-pixels in another row adjacent to the row. The plurality of first sub-pixels may face the plurality of second sub-pixels in a diagonal direction, and the plurality of third sub-pixels may also face the plurality of second sub-pixels in a diagonal direction. Therefore, the plurality of sub-pixels may be arranged in a lattice structure.

[0069] According to the arrangement of the first sub-pixel, the second sub-pixel and the third sub-pixel in the display area, the optical display panel can be classified into a symmetrically structured corrugated tile matrix and an asymmetrically structured corrugated tile matrix.

[0070] Figure 2 is a plan view of one embodiment of a panel including a matrix of corrugated tiles having a symmetrical structure.

[0071] Reference Figure 2 (a), the panel has a display area (10A), in which there is no light blocking layer (BM), and red light-emitting pixels (20a), green light-emitting pixels (20b) and blue light-emitting pixels (20c) are repeatedly arranged in the form of columns and rows. When a unit composed of three light-emitting pixels including the red light-emitting pixel (20a), the green light-emitting pixel (20b) and the blue light-emitting pixel (20c) is called a pixel unit, the symmetrical structure of the wave tile matrix means the following structure: in the structure, the red light-emitting pixels (20a), the green light-emitting pixels (20b) and the blue light-emitting pixels (20c) are arranged in the display area (10A) so that the other pixels are arranged symmetrically in the vertical direction and the lateral direction relative to the green light-emitting pixel (20b).

[0072] Reference Figure 2 (b), the optical display panel may be alternately provided with display areas A each of which does not contain a light blocking layer (BM) and display areas (10A) and (10B) each of which includes a light blocking layer (BM). In both the display area (10A) and the display area (10B), red light-emitting pixels (20a), green light-emitting pixels (20b) and blue light-emitting pixels (20c) are repeatedly arranged in the form of columns and rows. The symmetrical structure of the corrugated tile matrix means the following structure: in the structure, the red light-emitting pixels (20a), the green light-emitting pixels (20b) and the blue light-emitting pixels (20c) are arranged in both the display area (10A) and the display area (10B) so that the other pixels are arranged symmetrically in the vertical direction and the lateral direction relative to the green light-emitting pixels (20b).

[0073] Figure 3 is a plan view of one embodiment of a panel including a corrugated tile matrix having an asymmetric structure.

[0074] Reference Figure 3The panel has a display area (10C), in which the light blocking layer (BM) does not exist, and a plurality of pixel units each including a red light-emitting pixel (20a), a green light-emitting pixel (20b), and a blue light-emitting pixel (20c) are repeatedly arranged. The wave-tile matrix of an asymmetric structure means the following structure: in the structure, the red light-emitting pixel (20a), the green light-emitting pixel (20b), and the blue light-emitting pixel (20c) are arranged so as not to be symmetrical in the vertical direction and the lateral direction.

[0075] although Figure 1 Although not shown in the figure, the optical display panel may also include various typical optical devices used in light-emitting diode displays. For example, the optical display panel may also include an electron injection layer, an electron transport layer, a hole transport layer, a hole injection layer, a conductive layer including ITO, a substrate, etc. In addition, the optical display panel may also include a sealing layer to protect the light-emitting layer.

[0076] Polarizing Plate

[0077] The polarizing plate includes a polarizer and a retardation film laminate interposed between the optical display panel and the polarizer.

[0078] The polarizer is stacked on the upper surface of the retardation film stack, that is, on the surface of the retardation film stack facing the optical display panel.

[0079] The polarizer is used to convert external light or light emitted from the retardation film stack into polarized light by linear polarization of light, thereby reducing the reflection color value and reflectivity over the entire viewing angle range.

[0080] The polarizer may have a degree of polarization of 99% or more and a single light transmittance (Ts) of 42% or more. By satisfying both the degree of polarization and the single light transmittance, the polarizer can significantly reduce the reflectivity when stacked on a delay film laminate. Here, "single light transmittance" means a single light transmittance (Ts) measured in the visible spectrum (e.g., at a wavelength of 400 nanometers to 700 nanometers), and can be measured by typical methods known to those skilled in the art. "Degree of polarization" can be measured by typical methods known to those skilled in the art. Specifically, the polarizer may have a degree of polarization of 99% to 99.9999% and a single light transmittance of 42% to 50%.

[0081] When using polyvinyl alcohol film to manufacture polarizer, the light absorption axis of polarizer corresponds to the stretching direction of polarizer, for example, the machine direction (MD) of polarizer. Polarizer may include polyvinyl alcohol polarizer manufactured by uniaxial stretching polyvinyl alcohol film. In one embodiment, polarizer can be manufactured by dyeing, stretching, cross-linking and color correction of polyvinyl alcohol film. Polarizer with polarization degree and single transmittance in the above range can be achieved by adjusting the conditions of dyeing, stretching, cross-linking and color correction in a suitable manner. Polarizer may have a thickness of 5 microns to 40 microns. Within this range, polarizer can be used in polarizing plate.

[0082] The polarizing plate may further include an adhesive layer, a bonding layer, an adhesive / bonding layer, the following protective layer, and a combination thereof between the polarizer and the retardation film laminate.

[0083] Retardation film stack

[0084] The retardation film laminate has (i) an in-plane retardation (Re) of 140 nm to 200 nm at a wavelength of 550 nm, (ii) a biaxiality (NZ) of greater than 0.5 to less than 1.0 at a wavelength of 550 nm, and (iii) a slow axis tilted at an angle of +15° to +30° or -30° to -15° relative to the light absorption axis of the polarizer at a wavelength of 550 nm. Within this range, the polarizing plate can reduce the reflection color value and reflectivity over the entire viewing angle range, and the light absorption axis of the polarizer is tilted at an angle of 40° to 50° or 130° to 140° relative to the long side direction of the optical display panel.

[0085] As used herein, positive (+) angles and negative (-) angles refer to clockwise and counterclockwise directions, respectively, relative to 0°.

[0086] The retardation film stack may have wavelengths of, for example, 140 nm, 141 nm, 142 nm, 143 nm, 144 nm, 145 nm, 146 nm, 147 nm, 148 nm, 149 nm, 150 nm, 151 nm, 152 nm, 153 nm, 154 nm, 155 nm, 156 nm, 157 nm, 158 nm, 159 nm, 160 nm, 161 nm, 162 nm, 163 nm, 164 nm, 165 nm, 166 nm, 167 nm, 168 nm, 169 nm, 170 nm, 171 nm, 172 nm, 173 nm, 174 nm, 175 nm, 176 nm, 177 nm, 178 nm, 179 nm, 180 nm, 181 nm, 182 nm, 183 nm, 184 nm The in-plane retardation of 145 to 190 nm, or 150 to 180 nm, can be more preferably achieved.

[0087] The retardation film stack may have a biaxiality of, for example, 0.51, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 0.99, 0.55 to 0.9, or 0.6 to 0.8 at a wavelength of 550 nm. Within this range, the effects of the present invention can be better ensured.

[0088] Here, it should be noted that the slow axis of the delay film stack is different from the slow axis of any one of the delay layers in the delay film stack. That is, the delay film stack includes a plurality of delay layers, each of which has a slow axis in its in-plane direction. The inclination angle of the slow axis of the delay film stack relative to the light absorption axis of the polarizer may be different from the inclination angle of the slow axis of each of the delay layers relative to the light absorption axis of the polarizer.

[0089] The inventors of the present invention set the light absorption axis of the polarizer to be inclined at an angle of 40° to 50° or 130° to 140° relative to the long side direction of the optical display panel, and adjusted the inclination angle of the slow axis of the delay film stack relative to the light absorption axis of the polarizer to reduce the reflection color value and reflectivity over the entire viewing angle range while eliminating the above-mentioned black screen phenomenon.

[0090] The inclination angle of the slow axis of the delay film stack relative to the light absorption axis of the polarizer can be measured by a typical method known to those skilled in the art, and can be determined by checking nx, ny and nz (nx and ny represent the refractive index in the axis direction providing the highest refractive index in the in-plane direction and the refractive index in the axis direction providing the lowest refractive index in the in-plane direction, respectively, and nz represents the refractive index in the thickness direction) using an Axion scanner at a wavelength of 550 nanometers.

[0091] In one embodiment, the retardation film stack may have an out-of-plane retardation of 0 nm to 60 nm (e.g., 0 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, or 10 nm to 40 nm) at a wavelength of 550 nm. Within this range, the effects of the present invention can be easily achieved.

[0092] The retardation film stack may include a positive C layer. For example, the retardation film stack substantially includes a positive C layer.

[0093] The positive C layer enables the retardation film stack to easily achieve the above ranges of in-plane retardation and biaxiality while reducing the reflection color value at diagonal angles (especially at 60°).

[0094] The positive C layer may be a retardation layer satisfying the following Relationship 1. Therefore, the polarizing plate can reduce color scattering at the side.

[0095] [Equation 1]

[0096] nz>nx≒ny

[0097] (wherein nx, ny and nz represent the refractive index of the positive C layer in the slow axis direction, fast axis direction and thickness direction at a wavelength of 550 nanometers, respectively).

[0098] In one embodiment, the positive C layer may have an out-of-plane retardation of -150 nm to 0 nm (e.g., -150 nm, -145 nm, -140 nm, -135 nm, -130 nm, -125 nm, -120 nm, -115 nm, -110 nm, -105 nm, -100 nm, -95 nm, -90 nm, -85 nm, -80 nm, -75 nm, -70 nm, -65 nm, -60 nm, -55 nm, -50 nm, -45 nm, -40 nm, -35 nm, -30 nm, -25 nm, -20 nm, -15 nm, -10 nm, -5 nm, 0 nm, -130 nm to -10 nm, or -110 nm to -20 nm) at a wavelength of 550 nm. Within this range, the effect of the present invention may be further improved.

[0099] In one embodiment, the positive C layer may have an in-plane retardation of 0 nm to 10 nm (e.g., 0 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, or 0 nm to 5 nm) at a wavelength of 550 nm. Within this range, the effect of the present invention can be further improved.

[0100] The positive C layer may be a stretched film or a coating, as long as the positive C layer can achieve the above retardation value.

[0101] In one embodiment, the positive C layer may be a stretched film. The stretched film may be formed of a composition including a typical polymer known to those skilled in the art (eg, a fumaric acid diester-based resin), but is not limited thereto.

[0102] In another embodiment, the positive C layer may be a coating. The material used for the coating may be a liquid crystal material or a non-liquid crystal material to achieve the above-mentioned surface retardation of the positive C layer. The liquid crystal may be selected from typical types of liquid crystals known to those skilled in the art. For example, the liquid crystal may include a nematic liquid crystal. The non-liquid crystal material may include a cellulose material (e.g., cellulose ester, cellulose ether, etc.), a polystyrene material, etc. The cellulose material and the polystyrene material may include the following materials.

[0103] The positive C layer can be formed by a typical method known to those skilled in the art.

[0104] The positive C layer may have a thickness of greater than 0.1 micrometers to 20 micrometers (eg, 0.5 micrometers to 10 micrometers or 1 micrometer to 5 micrometers). Within this range, the positive C layer may be used in a polarizing plate.

[0105] In the retardation film stack, the positive C layer may be disposed at a position closer to the polarizer than any other retardation layer (eg, the first retardation layer and the second retardation layer described below) in the retardation film stack.

[0106] The retardation film laminate may include a film or a coating containing a polymer having positive intrinsic birefringence as a main component of the retardation film laminate. When the polymer having positive intrinsic birefringence is present as a main component of the retardation film laminate, the effect of the present invention can be better ensured.

[0107] Here, when referring to the main component, the retardation film laminate includes only the positive C layer and the retardation layer capable of achieving a predetermined range of in-plane retardation at a wavelength of 550 nanometers, and excludes the adhesive layer, the bonding layer, or the adhesive / bonding layer. The main component means that the corresponding component is present in an amount of 80 wt% or more (e.g., 85 wt% to 99 wt% or 85 wt% to 95 wt%) based on all the components in the retardation film laminate.

[0108] Positive intrinsic birefringence of a film means that the refractive index of the film increases in its stretching direction (eg, MD).

[0109] The polymer having positive intrinsic birefringence may include at least one selected from the following materials: cyclic olefin polymer (COP), such as norbornene polymer, etc.; polyester, such as polyethylene terephthalate (PET), polybutylene terephthalate, etc.; polyvinyl alcohol; polyvinyl chloride; polyaryl sulfone; polyolefin, such as polyethylene, polypropylene, etc.; polyarylate; and rod-shaped liquid crystal polymer. For example, the polymer may include polyolefin, cyclic olefin polymer (COP) or cyclic olefin copolymer (COC) showing good mechanical properties, heat resistance, transparency and dimensional stability, or may include polycarbonate showing good phase retardation and low temperature elongation. These polymers having positive intrinsic birefringence may be used alone or in the form of a mixture thereof. For example, the polymer may be a cyclic olefin polymer or a cyclic olefin copolymer.

[0110] The retardation film stack may have a thickness of 5 to 60 μm (eg, 10 to 50 μm). Within this range, the retardation film stack can be used in the optical display device, and the effects of the present invention can be easily achieved.

[0111] The retardation film stack may further include at least one type (preferably at least two types) of retardation layers having different in-plane retardation values. The at least two types of retardation layers are classified into a first retardation layer and a second retardation layer according to Equation 2:

[0112] [Equation 2]

[0113] The in-plane retardation of the first retardation layer at a wavelength of 550 nanometers is less than the in-plane retardation of the second retardation layer at a wavelength of 550 nanometers.

[0114] First delay layer

[0115] The first retardation layer may have an in-plane retardation of 80 nm to 145 nm at a wavelength of 550 nm. Within this range, the retardation film stack can easily achieve a predetermined range of in-plane retardation. For example, the first retardation layer may have an in-plane retardation of 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 105 nm, 110 nm, 115 nm, 120 nm, 125 nm, 130 nm, 135 nm, 140 nm, 85 nm to 140 nm, or 90 nm to 130 nm.

[0116] The first retardation layer may exhibit positive wavelength dispersion. Positive wavelength dispersion means that the in-plane retardation gradually increases from long wavelength to short wavelength. Therefore, when applied to the optical display device, the polarizing plate can help reduce color scattering and reflectivity. Specifically, the first retardation layer may satisfy the following equations 3 and 4:

[0117] [Equation 3]

[0118] 1.0 <Re(450) / Re(550)≤1.2

[0119] [Equation 4]

[0120] 0.9≤Re(650) / Re(550)<1.0

[0121] (wherein Re(450), Re(550) and Re(650) are the in-plane retardations of the first retardation layer at wavelengths of 450 nm, 550 nm and 650 nm, respectively (unit: nanometer)).

[0122] In one embodiment, the first retardation layer may have a Re(450) / Re(550) value of 1.05 to 1.2 (e.g., 1.05 to 1.15). In one embodiment, the first retardation layer may have a Re(650) / Re(550) value greater than 0.9 to 0.95. Within this range, the first retardation layer can ensure a good effect of reducing the front reflectivity and the lateral reflectivity.

[0123] In one embodiment, the first retardation layer may have an in-plane retardation of 80 to 160 nanometers (e.g., 85 to 140 nanometers or 90 to 130 nanometers) at a wavelength of 450 nanometers. Within this range, the first retardation layer can ensure the above wavelength dispersion and can reduce the front reflectivity and the lateral reflectivity.

[0124] In one embodiment, the first retardation layer may have an in-plane retardation of 80 nm to 140 nm (e.g., 85 nm to 130 nm or 90 nm to 120 nm) at a wavelength of 650 nm. Within this range, the first retardation layer can achieve the above wavelength dispersion and can reduce the front reflectivity and the lateral reflectivity.

[0125] The first retardation layer may satisfy the following Relationship 5. Therefore, the polarizing plate may reduce the reflectivity of the side.

[0126] [Equation 5]

[0127] nx≒nz>ny

[0128] (wherein nx, ny and nz represent the refractive index of the first retardation layer in the slow axis direction, the fast axis direction and the thickness direction at a wavelength of 550 nanometers, respectively).

[0129] In one embodiment, the first retardation layer may be a negative A retardation layer. Therefore, the first retardation layer may reduce the reflectivity of the side.

[0130] The slow axis of the first retardation layer may be tilted at an angle within a specific range relative to the light absorption axis of the polarizer. Assuming that the light absorption axis of the polarizer is 0°, the angle between the light absorption axis of the polarizer and the slow axis of the first retardation layer may be in the range of +79° to +89° or -89° to -79°. Within this range, even when the polarizer is bonded to the first retardation layer by a roll-to-roll process, the first retardation layer can help reduce color scattering and reflectivity while improving processability by ensuring the effects of the present invention. For example, the angle may be +79°, +80°, +81°, +82°, +83°, +84°, +85°, +86°, +87°, +88°, +89°, -89°, -88°, -87°, -86°, -85°, -84°, -83°, -82°, -81°, -80°, -79°, +80° to +88°, -88° to -80°, +82° to +86°, or -86° to -82°.

[0131] This angle can be achieved by adjusting the angle between the light absorption axis of the polarizer and the slow axis of the first retardation layer when attaching the first retardation layer of the retardation film stack to the polarizer.

[0132] The first retardation layer may have an out-of-plane retardation of -110 nm to -50 nm (e.g., -110 nm, -105 nm, -100 nm, -95 nm, -90 nm, -85 nm, -80 nm, -75 nm, -70 nm, -65 nm, -60 nm, -55 nm, -50 nm, -110 nm to -60 nm, or -100 nm to -70 nm) at a wavelength of 550 nm. Within this range, the first retardation layer may improve front reflectivity and lateral reflectivity.

[0133] The first retardation layer may have a biaxiality of -1.0 to 0.5 (e.g., -1.0, -0.9, -0.8, -0.7, -0.6, -0.5, -0.4, -0.3, -0.2, -0.1, 0, 0.1, 0.2, 0.3, 0.4, 0.5, -1.0 to 0, or -1.0 to less than 0) at a wavelength of 550 nanometers. Within this range, the first retardation layer may improve front reflectivity and lateral reflectivity.

[0134] The first retardation layer may have a thickness of 2 micrometers to 15 micrometers (eg, 3 micrometers to 10 micrometers). Within this range, the first retardation layer may be used in the polarizing plate.

[0135] In one embodiment, the first retardation layer may be a non-liquid crystal layer.

[0136] The first retardation layer may be formed of a composition including a resin having negative intrinsic birefringence. Negative intrinsic birefringence means that the refractive index of the film increases in a direction orthogonal to its stretching direction (eg, MD).

[0137] The resin having negative intrinsic birefringence may include compounds such as polymers having negative intrinsic birefringence. The polymer having negative intrinsic birefringence may include at least one selected from the following materials, but is not limited thereto: polystyrene polymers, including homopolymers of styrene or styrene derivatives, and copolymers of styrene or styrene derivatives and comonomers; poly(acrylonitrile) polymers; poly(methyl methacrylate) copolymers; and cellulose copolymers, such as cellulose esters. The comonomer may include at least one selected from acrylonitrile, maleic anhydride, methyl methacrylate and butadiene. Specifically, the first retardation layer may include at least one of a polystyrene compound and / or a cellulose compound, and more preferably a polystyrene compound. The compound may refer to a polymer, a copolymer or a resin.

[0138] In one embodiment, the cellulose-based copolymer may include a cellulose ester polymer having a unit as represented by Formula 1, in which the hydrogen (H) of at least some hydroxyl groups (OH) [C2 hydroxyl group, C3 hydroxyl group or C6 hydroxyl group] of the sugar monomer constituting the cellulose is unsubstituted or substituted with an acyl group. Here, the acyl group may be a substituted or unsubstituted acyl group.

[0139] [Formula 1]

[0140]

[0141] (where n is an integer of 1 or greater)

[0142] In one embodiment, the polystyrenic polymer may include a repeating unit of Formula 2.

[0143] [Formula 2]

[0144]

[0145] (In the above chemical formula 1,

[0146] The wavy lines are the connecting points.

[0147] R 1 , R 2 and R 3 are each independently a hydrogen atom, an unsubstituted alkyl group, a substituted alkyl group, or a halogen;

[0148] R is each independently alkyl, substituted alkyl, halogen, hydroxy, carboxyl, nitro, alkoxy, amine, sulfonate, phosphate, acyl, acyloxy, phenyl, alkoxycarbonyl or cyano,

[0149] R 1 , R 2 and R 3 is halogen and / or at least one R is halogen; and

[0150] n is an integer from 0 to 5).

[0151] In one embodiment, halogen refers to fluorine (F), Cl, Br or I, preferably F.

[0152] In one embodiment, in addition to the resin having negative intrinsic birefringence, the first retardation layer may further include typical additives, such as plasticizers, colorants (such as pigments and dyes), heat stabilizers, light stabilizers, ultraviolet (UV) absorbers, antistatic agents, antioxidants, particulates, surfactants, etc., but are not limited thereto.

[0153] In one embodiment, the positive wavelength dispersion of the first retardation layer may be adjusted in consideration of not only the type of resin having negative intrinsic birefringence but also the ratio of monomers in the resin.

[0154] Second delay layer

[0155] The second retardation layer may have an in-plane retardation of 180 nm to 250 nm at a wavelength of 550 nm. Within this range, the retardation film stack can easily achieve a predetermined range of in-plane retardation. For example, the second retardation layer may have an in-plane retardation of 180 nm, 185 nm, 190 nm, 195 nm, 200 nm, 205 nm, 210 nm, 215 nm, 220 nm, 225 nm, 230 nm, 235 nm, 240 nm, 245 nm, 250 nm, 185 nm to 245 nm, 190 nm to 240 nm, or 195 nm to 235 nm.

[0156] The second retardation layer may exhibit positive wavelength dispersion. Specifically, the second retardation layer may satisfy the following equations 6 and 7:

[0157] [Equation 6]

[0158] 1.0 <Re(450) / Re(550)≤1.1

[0159] [Equation 7]

[0160] 0.9≤Re(650) / Re(550)<1.0

[0161] (wherein Re(450), Re(550) and Re(650) are the in-plane retardations of the second retardation layer at wavelengths of 450 nm, 550 nm and 650 nm, respectively (unit: nanometer)).

[0162] In one embodiment, the second retardation layer may have a Re(450) / Re(550) value of 1.005 to 1.05. Within this range, the second retardation layer can ensure good effects of reducing front reflectivity and lateral reflectivity.

[0163] In one embodiment, the second retardation layer may have a Re(650) / Re(550) value of 0.95 to less than 1.00. Within this range, the second retardation layer can ensure good effects of reducing front reflectivity and lateral reflectivity.

[0164] In one embodiment, the second retardation layer may have an in-plane retardation of 180 nm to 250 nm (e.g., 185 nm to 245 nm, 190 nm to 240 nm, 195 nm to 235 nm, or 200 nm to 230 nm) at a wavelength of 450 nm. Within this range, the second retardation layer can ensure the above wavelength dispersion and can reduce the front reflectivity and the lateral reflectivity.

[0165] In one embodiment, the second retardation layer may have an in-plane retardation of 175 nm to 250 nm (e.g., 180 nm to 245 nm, 185 nm to 240 nm, or 190 nm to 235 nm) at a wavelength of 650 nm. Within this range, the second retardation layer can achieve the above wavelength dispersion while reducing the front reflectivity and the side reflectivity.

[0166] The slow axis of the second retardation layer may be tilted at an angle within a specific range relative to the light absorption axis of the polarizer (MD of the polarizer). Assuming that the light absorption axis of the polarizer is 0°, the angle between the light absorption axis of the polarizer and the slow axis of the second retardation layer may be in the range of +14° to +24° or -24° to -14°. Within this range, even when the polarizer is bonded to the first retardation layer by a roll-to-roll process, the second retardation layer can help reduce color scattering and reflectivity while improving processability by ensuring the effects of the present invention. For example, the angle may be +14°, +15°, +16°, +17°, +18°, +19°, +20°, +21°, +22°, +23°, +24°, -24°, -23°, -22°, -21°, -20°, -19°, -18°, -17°, -16°, -15°, -14°, +16° to +22°, -22° to -16°, +18° to +21°, or -21° to -18°.

[0167] In one embodiment, the second retardation layer may satisfy the following Relationship 8. Therefore, the polarizing plate may reduce the reflectivity of the side.

[0168] [Equation 8]

[0169] nx>ny≒nz

[0170] (wherein nx, ny and nz represent the refractive index of the second retardation layer in the slow axis direction, the fast axis direction and the thickness direction at a wavelength of 550 nanometers, respectively).

[0171] In one embodiment, the second retardation layer may be a positive A retardation layer. Therefore, the second retardation layer may reduce the reflectivity of the entire side.

[0172] The second retardation layer may have an out-of-plane retardation of 100 nm to 300 nm (e.g., 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm, 290 nm, 300 nm, 110 nm to 250 nm, or 150 nm to 250 nm) at a wavelength of 550 nm. Within this range, the second retardation layer may reduce the reflectivity of the entire side.

[0173] In one embodiment, the second retardation layer can have a biaxiality of 1.0 to 3.0, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9 or 3.0 (e.g., 1.0 to 2.0 or 1.0 to 1.5) at a wavelength of 550 nanometers. Within this range, the second retardation layer can reduce the reflectivity of the entire side.

[0174] In one embodiment, the second retardation layer may be a non-liquid crystal layer.

[0175] The second retardation layer can be formed of a composition containing a resin having positive intrinsic birefringence. Therefore, it is easy to form a second retardation layer having a higher refractive index in the stretching direction than in a direction orthogonal to the stretching direction.

[0176] The resin having positive intrinsic birefringence includes a polymer having positive intrinsic birefringence. The polymer having positive intrinsic birefringence may include at least one selected from, for example, the following materials: cycloolefin polymers and cycloolefin copolymers, such as norbornene polymers, etc.; polyesters, such as polyethylene terephthalate, polybutylene terephthalate, etc.; polyvinyl alcohol; polyvinyl chloride; polyaryl sulfone; polyolefins, such as polyethylene and polypropylene; polyarylate; and rod-shaped liquid crystal polymers. Specifically, the polymer may include a polyolefin or cycloolefin polymer (COP) exhibiting good mechanical properties, heat resistance, transparency and dimensional stability, or may include a polycarbonate exhibiting good phase retardation and low-temperature elongation. These polymers having positive intrinsic birefringence may be used alone or in the form of a mixture thereof. For example, the second retardation layer may be a cycloolefin polymer in consideration of oblique stretching, wavelength dispersion, etc.

[0177] The positive wavelength dispersion of the second retardation layer can be adjusted in consideration of not only the type of the resin having positive intrinsic birefringence but also the ratio of the monomers in the resin.

[0178] In addition to the resin having negative intrinsic birefringence, the second retardation layer may further include typical additives, for example, plasticizers, colorants (such as pigments and dyes), heat stabilizers, light stabilizers, UV absorbers, antistatic agents, antioxidants, microparticles, surfactants, etc., but are not limited thereto.

[0179] The second retardation layer may have a greater thickness than the first retardation layer, and may have a thickness of 5 micrometers to 100 micrometers, for example, 5 micrometers to 60 micrometers. Within this range, the second retardation layer may be used in the polarizing plate.

[0180] The second retardation layer can be manufactured in the following manner: an unstretched film is produced by melting, injection molding and press molding of a composition containing a resin having positive birefringence, and then the unstretched film is stretched in an oblique direction. The unstretched film can be stretched to 1.1 times or more, 4.0 times or more, or 1.3 times to 3.0 times. Within this range, the slow axis direction of the second retardation layer can be controlled, and the refractive index of the second retardation layer can be increased in the stretching direction. The unstretched film can be stretched at a temperature of the glass transition temperature (Tg) of the unstretched film + 2°C to Tg + 30°C.

[0181] The stretching direction can be set so that the polarizing plate can be easily produced by a roll-to-roll process while satisfying the angle of the slow axis of the second retardation layer with respect to the light absorption axis of the polarizer.

[0182] The second retardation layer is formed by stretching an unstretched film and may be present in the polarizing plate without other layers thereon. Alternatively, the second retardation layer may further include a primer layer to improve the bonding strength between the positive C layer and the first retardation layer. The primer layer may include at least one selected from acrylic resin, urethane resin, acrylic urethane resin, ester resin and ethyleneimide resin, but is not limited thereto.

[0183] Laminated body formed of first retardation layer and second retardation layer

[0184] The stacked body formed of the first retardation layer and the second retardation layer can exhibit negative wavelength dispersion in which the in-plane retardation gradually decreases from a long wavelength to a short wavelength.

[0185] In one embodiment, the laminate formed by the first retardation layer and the second retardation layer may have an in-plane retardation of 140 nm to 200 nm (e.g., 140 nm to 195 nm, 140 nm to 190 nm, or 150 nm to 190 nm) at a wavelength of 550 nm. Within this range, the laminate may reduce lateral reflectivity.

[0186] In one embodiment, the stacked body formed by the first retardation layer and the second retardation layer may have a wavelength of 5 nm to 200 nm (e.g., 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 105 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm, 290 nm, 300 nm, 310 nm, 310 nm, 320 nm, 330 nm, 350 nm, 360 nm, 370 nm, 380 nm, 390 nm, 400 nm, 410 nm, 410 nm, 420 nm, 430 nm, 440 nm, 450 nm, In some embodiments, the laminate may have an out-of-plane retardation of at least 1 nm (nm, 110 nm, 115 nm, 120 nm, 125 nm, 130 nm, 135 nm, 140 nm, 145 nm, 150 nm, 155 nm, 160 nm, 165 nm, 170 nm, 175 nm, 180 nm, 185 nm, 190 nm, 195 nm, 200 nm, 10 nm to 150 nm, 50 nm to 150 nm, or 50 nm to 100 nm). Within this range, the laminate may reduce lateral reflectivity.

[0187] The laminate formed of the first retardation layer and the second retardation layer may have a thickness of more than 0 μm to 70 μm, for example, 5 μm to 60 μm or 10 μm to 60 μm. Within this range, the laminate may be used in a polarizing plate.

[0188] In one embodiment, the stack formed by the first retardation layer and the second retardation layer may have a slow axis tilted at +15° to +30° or -30° to -15° relative to the light absorption axis of the polarizer. Within this range, the effect of the present invention can be easily achieved. The slow axis can be measured by the same method as measuring the slow axis of the retardation film stack. For example, the angle may be +15°, +16°, +17°, +18°, +19°, +20°, +21°, +22°, +23°, +24°, +25°, +26°, +27°, +28°, +29°, +30°, -30°, -29°, -28°, -27°, -26°, -25°, -24°, -23°, -22°, -21°, -20°, -19°, -18°, -17°, -16° or -15°.

[0189] The stacked body formed by the first retardation layer and the second retardation layer will be described in detail below.

[0190] In one embodiment, the second retardation layer may be a stretched film.The second retardation layer may be bonded to the first retardation layer through an adhesive layer and / or a bonding layer.

[0191] The second retardation layer can be manufactured in the following manner: an unstretched film is produced by melting, injection molding and press molding the composition for the second retardation layer, and then the unstretched film is stretched in the oblique direction. The unstretched film can be stretched to 1.1 times or more, 4.0 times or more, or 1.3 times to 3.0 times. Within this range, the slow axis direction of the second retardation layer can be controlled, and the refractive index of the second retardation layer can be increased in the stretching direction. The unstretched film can be stretched at a temperature of +2°C to Tg+30°C of the glass transition temperature (Tg) of the unstretched film. The stretching direction can be set so that the polarizing plate can be easily made by roll-to-roll processing, while satisfying the angle of the slow axis of the second retardation layer relative to the light absorption axis of the polarizer.

[0192] The first delay layer can be formed by coating a composition for the first delay layer on a base film, drying the composition, uniaxially stretching or biaxially stretching the dried coating and the base film as a whole at a predetermined ratio in the MD or transverse direction (TD) of the base film, and peeling off the base film.

[0193] In another embodiment, the second retarder layer may be a coating.

[0194] The second delay layer can be formed directly on the first delay layer without an adhesive layer or a bonding layer. Therefore, the laminate formed by the first delay layer and the second delay layer can be bonded to the polarizer by roll-to-roll processing, thereby improving processability and yield by suppressing process failure. Although the first delay layer has an in-plane delay different from that of the second delay layer, the first delay layer can be formed directly on the second delay layer, thereby reducing the thickness of the polarizing plate while improving processability.

[0195] In still another embodiment, the first retardation layer may be formed by simultaneously obliquely stretching a laminate obtained by coating a film for the second retardation layer and the above-mentioned composition for the first retardation layer.

[0196] The laminate formed by the first retardation layer and the second retardation layer can be stacked on the lower surface of the polarizer, that is, stacked between the polarizer and the panel. In one embodiment, the first retardation layer and the second retardation layer can be stacked in this order from the polarizer. In another embodiment, the second retardation layer and the first retardation layer can be stacked in this order from the polarizer.

[0197] An adhesive layer or a bonding layer may be formed on the lower surface of the retardation film laminate so that the polarizing plate can be adhesively attached to the optical display panel through the adhesive layer or the bonding layer.

[0198] For the stacked body formed by the first retardation layer and the second retardation layer, at least one protective layer may be further formed on at least one of the upper surface of the first retardation layer, between the first retardation layer and the second retardation layer, and the lower surface of the second retardation layer.

[0199] The retardation film stack may further include at least one protective layer described below.

[0200] Protective layer

[0201] A protective layer may be stacked on the upper surface of the polarizer to protect the polarizer. The protective layer is used to protect the polarizer while improving the reliability and mechanical strength of the polarizing plate. If the mechanical properties of the polarizing plate can be ensured even without the protective layer, the protective layer may be omitted. The protective layer may be stacked on the upper surface of the polarizer singly, or a plurality of protective layers may be stacked on the upper surface of the polarizer.

[0202] The protective layer may include an optically transparent protective film and / or an optically transparent protective coating. The protective film may include a film formed of at least one selected from the following materials, but not limited thereto: cellulose ester resins, including triacetylcellulose (TAC), etc.; cyclic polyolefin resins, including amorphous cyclic olefin polymers (COP), etc.; polycarbonate resins; polyester resins, including polyethylene terephthalate (PET), etc.; polyether sulfone resins; polysulfone resins; polyamide resins; polyimide resins; non-cyclic polyolefin resins; polyacrylate resins, including poly(methyl methacrylate), etc.; polyvinyl alcohol resins; polyvinyl chloride resins; and polyvinylidene chloride resins.

[0203] The protective coating layer may be formed of a composition containing an actinic radiation curable compound and a polymerization initiator. The actinic radiation curable compound may include at least one selected from a cationically polymerizable curable compound, a free radically polymerizable curable compound, a urethane resin, and a silicone resin.

[0204] The protective layer may be a non-retardation film, or may have an in-plane retardation within a predetermined range. For example, the protective layer may have an in-plane retardation of less than 5,000 nm, 5,000 nm, or greater than 5,000 nm, 120 nm to 160 nm, or 5 nm to 0 nm at a wavelength of 550 nm. Within this range, the protective layer can protect the polarizing plate without affecting the effect of the retardation film laminate.

[0205] The protective layer may have a thickness of 10 micrometers or less, 5 micrometers to 300 micrometers, 5 micrometers or less, or 5 micrometers to 200 micrometers. Within this range, the protective layer can be used in a polarizing plate.

[0206] The polarizing plate may further include a functional coating layer on the upper surface of the protective layer. The functional coating layer may include at least one selected from the group consisting of a hard coating layer, a fingerprint-resistant layer, an anti-reflection layer, an anti-glare layer, a low reflectivity layer, and an ultra-low reflectivity layer, but is not limited thereto.

[0207] Figure 4 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention. Figure 4 The polarizing plate may include: a polarizer (210); a protective layer (220) stacked on the upper surface of the polarizer (210); and a positive C layer (230), a second retardation layer (240) and a first retardation layer (250) stacked in sequence on the lower surface of the polarizer (210). The stack formed by the positive C layer (230), the second retardation layer (240) and the first retardation layer (250) may be a retardation film stack.

[0208] The optical display apparatus may further include a protective substrate on the polarizing plate, in addition to the optical display panel and the polarizing plate.

[0209] Invention Mode

[0210] Next, the present invention will be described in more detail with reference to some examples. However, it should be noted that these examples are provided only for illustration and should not be interpreted as limiting the present invention in any way.

[0211] Example 1

[0212] A polarizer having a single transmittance of 45% was prepared by uniaxially stretching a polyvinyl alcohol-based film (pre-stretched thickness: 60 μm, Kuraray) in an iodine aqueous solution at 55° C. in the MD of the film to 6 times its original length.

[0213] The second retardation layer (positive wavelength dispersion, Re@550nm=221nm, thickness: 42 micrometers) was prepared by obliquely stretching a cycloolefin polymer (COP) film in the MD of the film to 2.3 times its original length at 140°C.

[0214] A first retardation layer (positive wavelength dispersion, Re@550nm=90nm, NZ=about-0.1, thickness: 4 μm) was prepared by dissolving a composition containing a fluorine-substituted polystyrene polymer in methyl ethyl ketone, applying the resulting solution on one surface of a PET film to form a coating, drying the coating, and uniaxially stretching the coating and the PET film as a whole to 1.6 times on the MD of the PET film at 130°C, and then removing the PET film.

[0215] A positive (+) C layer (Rth@550nm=-32nm) was prepared by dissolving a composition containing a fluorine-substituted polystyrene polymer in methyl ethyl ketone, applying the resulting solution on one surface of a PET film to form a coating, drying the coating, and then removing the PET film.

[0216] The retardation film laminate was prepared by bonding the first retardation layer to the lower surface of the COP film corresponding to the second retardation layer with an adhesive layer and bonding the positive (+) C layer to the upper surface of the COP film with an adhesive layer.

[0217] The positive (+) C layer of the delay film stack is adhered to the lower surface of the prepared polarizer through an adhesive layer, and the triacetyl cellulose (TAC) film is adhered to the upper surface of the polarizer, thereby preparing a polarizing plate in which the TAC film, polarizer, positive (+) C layer, second delay layer and first delay layer are stacked in sequence.

[0218] A module for a display device is prepared by preparing a panel including a corrugated tile matrix with a symmetrical structure and attaching the panel to a polarizing plate through an adhesive layer so that the light absorption axis of the polarizer is inclined at an angle of 45° relative to the long side direction of the panel.

[0219] Example 2

[0220] A polarizing plate was prepared in the same manner as in Example 1 except for the following: a second delay layer (Re@550 nm=238 nm) was prepared by obliquely stretching a cycloolefin polymer (COP) film by 2.6 times in the MD of the film at 140°C, and a first delay layer was prepared by dissolving a composition containing a fluorine-substituted polystyrene polymer in methyl ethyl ketone, applying the resulting solution on one surface of a PET film to form a coating, drying the coating, uniaxially stretching the coating and the PET film as a whole to 1.8 times in the MD of the PET film at 130°C, and then removing the PET film.

[0221] Example 3

[0222] A module for a display device was prepared in the same manner as in Example 1, except that a panel including a corrugated tile matrix having an asymmetric structure was prepared and the panel was attached to a polarizing plate so that the light absorption axis of the polarizer was inclined at an angle of 135° relative to the long side direction of the panel.

[0223] Example 4

[0224] A module for a display device was prepared in the same manner as in Example 2, except that a panel including a corrugated tile matrix having an asymmetric structure was prepared and the panel was attached to a polarizing plate so that the light absorption axis of the polarizer was inclined at an angle of 135° relative to the long side direction of the panel.

[0225] Comparative Examples 1 to 6

[0226] The module for a display device was prepared in the same manner as in Example 1, except that each component of the module was changed as listed in Table 1.

[0227] Comparative Example 7

[0228] A monolithic retardation layer (Re@550 nm=140 nm) was prepared by stretching a polymer alloy (comprising a fluorine-containing polyester and an aromatic resin) film to 2.3 times in a stretching direction at 45° with respect to the MD of the film at 140° C. The monolithic retardation layer was attached to a polarizer prepared in the same manner as in Example 1, thereby preparing a polarizing plate in which a TAC film, a polarizer, and a monolithic retardation layer were stacked in sequence.

[0229] The module for a display device was prepared in the same manner as in Example 1, except that each component of the module was changed as listed in Table 1.

[0230] The phase retardation of the retardation film stack was measured using an Axion scanner (Axometrics). The following properties of the modules for optical display devices prepared in Examples and Comparative Examples were evaluated, and the evaluation results are shown in Tables 1 and Figures 5 to 7 middle.

[0231] (1) Black screen: After operating the module by supplying power to the module, it was evaluated whether the module suffered from a black screen phenomenon that made the screen of the module invisible when viewed through polarized sunglasses.

[0232] (2) Reflection color value for external light: The reflection color value was measured using DMS 803 (Instrument System, (Konica Minolta Group)). After measuring the reflection color value with reference to a white plate of DMS 803, the reflection color value was measured using the Angular Scan function. θ was measured in units of 5°, and the reflection color values ​​a* and b* were measured in all directions at incident angles of 8°, 30°, 45°, and 60°, and then the color value was calculated according to the equation: |maximum value of reflection color value a*|+|maximum value of reflection color value b*|. In all directions at incident angles of 8°, 30°, 45°, and 60°, a lower value of |maximum value of reflection color value a*|+|maximum value of reflection color value b*| is more preferable. For example, |maximum value of reflection color value a*|+|maximum value of reflection color value b*| less than 4 is preferable.

[0233] [Table 1]

[0234]

[0235] [Table 2]

[0236]

[0237] *Angle 1: The angle of the light absorption axis of the polarizer relative to the long side of the panel

[0238] *Angle 2: Angle of the slow axis of the retardation film stack relative to the light absorption axis of the polarizer

[0239] *Reflection color value: |Maximum value of reflection color value a*| + |Maximum value of reflection color value b*| when reflection color values ​​a* and b* are measured in all directions according to the incident angle of light

[0240] As shown in Table 1, the optical display device according to the present invention can solve the black screen phenomenon that makes the screen invisible when viewed through polarized sunglasses, while providing significantly low reflection color values ​​and reflectivity over the entire viewing angle range. Figure 5 and Figure 6 As shown in , the optical display device according to the present invention exhibits small changes in the reflected color values ​​a* and b*.

[0241] In contrast, as shown in Table 2, the module of Comparative Example 7 using a polarizing plate including a single retardation layer (monolayer type) has a higher reflection color value than the module of Example. In addition, the modules of Comparative Examples 1 to 6 that fail to meet the characteristics of the present invention also have higher reflection color values ​​than the module of Example. Figure 7 As shown in , the module of the comparative example exhibits large changes in the reflectance color values ​​a* and b*.

[0242] It should be understood that those skilled in the art can make various modifications, changes, variations and equivalent embodiments without departing from the spirit and scope of the present invention.

Claims

1. An optical display device, comprising an optical display panel and a polarizing plate stacked on the optical display panel, wherein the polarizing plate comprises: Polarizer; and a retardation film laminate, sandwiched between the optical display panel and the polarizer, wherein the light absorption axis of the polarizer is inclined at an angle of 40° to 50° or 130° to 140° relative to the long side direction of the optical display panel; and The delay film stack has an in-plane retardation (Re) of 140 nanometers to 200 nanometers and a biaxiality (NZ) of greater than 0.5 to less than 1.0 at a wavelength of 550 nanometers, and the slow axis of the delay film stack is inclined at an angle of +15° to +30° or -30° to -15° relative to the light absorption axis of the polarizer. 2 . The optical display device according to claim 1 , wherein the optical display panel has a corrugated tile matrix, and the corrugated tile matrix has a symmetrical structure or an asymmetrical structure. 3 . The optical display apparatus according to claim 1 , wherein the light absorption axis of the polarizer is inclined at an angle of 45° or 135° with respect to the long-side direction of the optical display panel. The optical display device according to claim 1 , wherein the retardation film stack comprises a positive C layer. 5 . The optical display device according to claim 4 , wherein the positive C layer is placed at a position of the retardation film stack closest to the polarizer. 6 . The optical display device according to claim 1 , wherein the retardation film stack comprises a film or a coating comprising a polymer having positive intrinsic birefringence. 7 . The optical display device according to claim 6 , wherein the polymer having positive intrinsic birefringence is present as a main component in the retardation film stack. 8 . The optical display device according to claim 6 , wherein the polymer having positive intrinsic birefringence comprises a cycloolefin polymer or a cycloolefin copolymer.

9. The optical display device according to claim 1, wherein the retardation film stack comprises a first retardation layer and a second retardation layer, and the first retardation layer and the second retardation layer satisfy Equation 2: [Equation 2] The in-plane retardation of the first retardation layer at a wavelength of 550 nanometers is less than the in-plane retardation of the second retardation layer at a wavelength of 550 nanometers. 10 . The optical display device according to claim 9 , wherein the first retardation layer has an in-plane retardation of 80 nm to 145 nm at a wavelength of 550 nm, and the second retardation layer has an in-plane retardation of 180 nm to 250 nm at a wavelength of 550 nm. 11 . The optical display device according to claim 9 , wherein the second retardation layer comprises a film or a coating containing a polymer having positive intrinsic birefringence. 12 . The optical display device according to claim 9 , wherein the second retardation layer has a thickness greater than that of the first retardation layer. 13 . The optical display apparatus according to claim 9 , wherein each of the first retardation layer and the second retardation layer exhibits positive wavelength dispersion.

14. The optical display apparatus of claim 9, wherein each of the first retardation layer and the second retardation layer is a non-liquid crystal layer.

15. The optical display apparatus according to claim 9, wherein the first retardation layer and the second retardation layer are stacked sequentially from the polarizer in the stated order. 16 . The optical display apparatus according to claim 4 , wherein the positive C layer comprises at least one selected from a cellulose-based compound and a polystyrene-based compound. 17 . The optical display apparatus according to claim 9 , wherein the first retardation layer comprises at least one selected from a cellulose-based compound and a polystyrene-based compound.

18. The optical display device according to claim 9, wherein the slow axis of the stacked body formed by the first retardation layer and the second retardation layer is inclined at an angle of +15° to +30° or -30° to -15° relative to the light absorption axis of the polarizer.

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