Polarizing plate and optical display device including the same

Abstract

Disclosed herein is a polarizing plate and an optical display device including the same. The polarizing plate includes: a polarizing sheet; and a first optical functional layer and a first protective layer sequentially stacked on one surface of the polarizing sheet, wherein the optical functional layer includes: a resin layer; and acicular microparticles, the resin layer has a glass transition temperature (Tg) of -70°C to -15°C and a storage modulus at 25°C of 1 x 10 ‑3 MPa to 9 x 10 ‑1 MPa, and the acicular microparticles are oriented in a planar direction of the first optical functional layer, and when an optical absorption axis of the polarizing sheet is 0°, an orientation angle of a longitudinal direction of the acicular microparticles with respect to the optical absorption axis of the polarizing sheet has an average value of -10° to +10° and a standard deviation of 15° or less.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of Korean Patent Application No. 10-2021-0097416, filed on July 23, 2021, with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] The present invention relates to a polarizing plate and an optical display device comprising the polarizing plate. Background Technology

[0004] A liquid crystal display (LCD) operates by allowing light emitted from a backlight unit to propagate through a light source-side polarizer, a liquid crystal panel, and a viewer-side polarizer in the stated order. The light emitted from the light source is diffused by the backlight unit before entering the light source-side polarizer. Because the diffused light passes through the light source-side polarizer, the liquid crystal panel, and the viewer-side polarizer, the contrast ratio of the LCD decreases from the front of the LCD towards its lateral side.

[0005] To improve frontal and lateral contrast or visibility, a contrast or visibility enhancement layer has been considered for incorporating into the viewer-side polarizer. Such a contrast or visibility enhancement layer includes a predetermined embossed or engraved optical pattern at the interface between a low-refractive-index layer and a high-refractive-index layer, such that light transmitted through the viewer-side polarizer is refracted via the optical pattern, thereby improving contrast or visibility.

[0006] However, contrast or visibility enhancement layers with such optical patterns necessarily require a patterning process. Furthermore, the contrast or visibility enhancement layer needs to consist of two layers: a low-refractive-index layer and a high-refractive-index layer. Generally, the patterning process employs hard or soft molding techniques, where a pattern with a specific spacing is engraved on a patterning roller and transferred to a film. However, even minute defects occurring on the patterning roller during the patterning process can be immediately reflected in the film to which the pattern will be transferred, leading to a deterioration in manufacturability. This can make the manufacturing process of polarizers complex and expensive, while also making it difficult to reduce the thickness of the polarizers.

[0007] The background technology of the present invention is disclosed in Korean Patent Publication No. 10-2018-0047569. Summary of the Invention

[0008] One object of the present invention is to provide a polarizing plate that can improve contrast and / or brightness without requiring an optical pattern or a patterned layer containing an optical pattern.

[0009] Another object of the present invention is to provide a polarizing plate that is easy to manufacture and reduces thickness by eliminating the need for optical patterns or patterned layers containing optical patterns.

[0010] Another aspect of the present invention is to provide a polarizing plate comprising an optical functional layer having good interlayer peel strength.

[0011] One aspect of the present invention relates to a polarizing plate.

[0012] 1. A polarizing plate comprises: a polarizer; and a first optical functional layer and a first protective layer, sequentially stacked on one surface of the polarizer, wherein the first optical functional layer comprises: a resin layer; and needle-like particles, the resin layer having a glass transition temperature (Tg) of -70°C to -15°C and a strength of 1×10⁻⁶ at 25°C. -3 From 9×10 MPa -1 The energy storage modulus of megapascals, the orientation of the needle-like particles in the plane of the first optical functional layer, and the orientation angle of the longitudinal direction of the needle-like particles relative to the optical absorption axis of the polarizer having an average value of -10° to +10° and a standard deviation of 15° or less than 15° when the optical absorption axis of the polarizer is 0°.

[0013] 2. In Example 1, the first optical functional layer may be a contrast or brightness enhancement layer.

[0014] 3. In Example 1 or Example 2, the needle-like particles may have an average aspect ratio of 5 to 60.

[0015] 4. In Examples 1 to 3, the needle-like particles may have a length of 10 micrometers to 30 micrometers and a diameter of 0.5 micrometers to 2 micrometers.

[0016] 5. In Examples 1 to 4, the needle-like microparticles may have a higher refractive index than the resin layer.

[0017] 6. In Examples 1 to 5, the needle-like particles may comprise particles formed from at least one selected from titanium dioxide, zirconium oxide, zinc oxide, calcium carbonate, boehmite, aluminum borate, calcium silicate, magnesium sulfate, magnesium sulfate hydrate, potassium titanate, glass, and synthetic resin.

[0018] 7. In Examples 1 to 6, the surface of the needle-like particles can be modified.

[0019] 8. In Example 7, the surface of the needle-like particles may be modified with at least one selected from silane coupling agents, surfactants, and oils.

[0020] 9. In Examples 1 to 8, needle-like microparticles may be present in the first optical functional layer in an amount of 1% to 30% by weight.

[0021] 10. In Examples 1 to 9, the resin layer may be an adhesive layer.

[0022] 11. In Examples 1 to 10, the resin layer may be formed from a composition comprising a non-birefringent resin.

[0023] 12. In Example 11, the resin may contain at least one selected from (meth)acrylate resins and polyester resins.

[0024] 13. In Example 11 or Example 12, the composition may further include a curing agent.

[0025] 14. In Examples 1 to 13, the first optical functional layer may have a thickness of 100 micrometers or less.

[0026] 15. In Examples 1 to 14, the first protective layer may include a delay film.

[0027] 16. In embodiment 15, the first protective layer may further include a functional layer, the functional layer comprising at least one selected from the following: a hard coating layer, a scattering layer, a low reflectivity layer, an ultra-low reflectivity layer, a base coating layer, a fingerprint-resistant layer, an anti-reflective layer, and an anti-glare layer.

[0028] 17. In Embodiments 1 to 16, the polarizing plate may further include: a second optical functional layer inserted between the first optical functional layer and the first protective layer.

[0029] 18. In Example 17, the second optical functional layer may include: a resin layer; and needle-like microparticles.

[0030] 19. In Example 18, the longitudinal direction of the needle-like particles in the second optical functional layer can form an orientation angle of 85° to 95° relative to the longitudinal direction of the needle-like particles in the first optical functional layer.

[0031] Another aspect of the present invention relates to an optical display device.

[0032] The optical display device includes a polarizing plate according to the present invention.

[0033] The present invention provides a polarizing plate that can improve contrast and / or brightness without requiring an optical pattern or a patterned layer containing an optical pattern.

[0034] The present invention provides a polarizing plate that is easy to manufacture and reduces thickness by eliminating the need for optical patterns or patterned layers containing optical patterns.

[0035] The present invention provides a polarizing plate comprising an optical functional layer having good interlayer peel strength. Attached Figure Description

[0036] Figure 1 This is a cross-sectional view of a polarizing plate according to an embodiment of the present invention.

[0037] Figure 2 This is a TEM image of needle-like particles according to an embodiment of the present invention.

[0038] Figure 3 This is a longitudinal cross-sectional view of needle-like particles according to an embodiment of the present invention.

[0039] Figure 4 This is a schematic diagram showing the distribution of the orientation angles of needle-like microparticles in a resin layer relative to the light absorption axis of a polarizer according to an embodiment of the present invention, assuming the light absorption axis is 90°.

[0040] Figure 5A This is an image showing the orientation of needle-like particles in a resin layer according to an embodiment, and Figure 5B This is a graph showing the distribution of measured values ​​of the orientation angle of the needle-like particles relative to the light absorption axis of the polarizer, assuming the light absorption axis is 90°.

[0041] Figure 6 This is a cross-sectional view of a polarizing plate according to another embodiment of the present invention. Detailed Implementation

[0042] In the following description, embodiments of the invention will be described in detail with reference to the accompanying drawings, enabling those skilled in the art to readily implement the invention. It should be understood that the invention may be embodied in different ways and is not limited to the following embodiments. In the drawings, parts unrelated to the description will be omitted for clarity. Throughout this specification, the same components will be indicated by the same reference numerals.

[0043] 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" and "lower surface" are used interchangeably. Furthermore, when an element, such as a layer or film, is referred to as being placed "on" another element, it may be placed directly on the other element, or there may be intervening elements. On the other hand, when an element is referred to as being placed "directly" on another element, there are no intervening elements.

[0044] In this article, "in-plane delay (Re)" refers to the value measured at a wavelength of 550 nm, as calculated according to Equation A:

[0045] [Equation A]

[0046] Re = (nx - ny) × d,

[0047] Where nx and ny are the refractive indices of the protective layer, measured at a wavelength of 550 nm in its slow and fast axis directions, respectively, and d is the thickness of the protective layer (in nanometers).

[0048] In this article, the term "(meth)acryloyl" refers to acryloyl and / or methacryloyl.

[0049] In this article, "refractive index" can be a value measured at wavelengths from 380 nm to 780 nm, specifically 550 nm.

[0050] In this article, the "modulus" of the resin layer refers to the energy storage modulus of the resin layer.

[0051] Storage modulus can be measured using the following procedure: First, a resin layer composition is applied to a release film to a dry thickness of 50 micrometers, followed by drying at 95°C for 4 minutes to form a resin layer. The resin layers formed as described above are stacked one after another to a thickness of 500 micrometers, and then cut into circles with a diameter of 8 millimeters to prepare samples. The storage modulus of the prepared samples at 25°C is measured using a storage modulus measuring instrument (Advanced Rheometric Expansion System (ARES), TA Instruments) at a heating rate of 10°C / min and a temperature range of 0°C to 100°C.

[0052] As used in this article to represent a specific numerical range, the expression "X to Y" means "≥X and ≤Y".

[0053] This invention provides a polarizing plate that can improve frontal and lateral contrast and / or brightness without requiring an optical pattern or a patterned layer containing an optical pattern. The polarizing plate according to the invention is easy to manufacture and reduces thickness by eliminating the need for an optical pattern or a patterned layer containing an optical pattern. Furthermore, this invention provides a polarizing plate comprising an optical functional layer having good interlayer peel strength.

[0054] The polarizing plate according to the present invention comprises: a polarizer; and a first optical functional layer and a first protective layer, sequentially stacked on one surface of the polarizer, wherein the first optical functional layer comprises: a resin layer; and needle-like particles, the resin layer having a glass transition temperature (Tg) of -70°C to -15°C and a strength of 1×10⁻⁶ at 25°C. -3 From 9×10 MPa -1 The energy storage modulus of megapascals, the orientation of the needle-like particles in the plane of the first optical functional layer, and the orientation angle of the longitudinal direction of the needle-like particles relative to the optical absorption axis of the polarizer having an average value of -10° to +10° and a standard deviation of 15° or less than 15° when the optical absorption axis of the polarizer is 0°.

[0055] In the following text, reference will be made to Figure 1 A polarizing plate according to an embodiment of the present invention is described. Figure 1 This is a cross-sectional view of the polarizing plate according to an embodiment.

[0056] refer to Figure 1 The polarizing plate may include a polarizer 10, a first protective layer 30, a first optical functional layer 20, a second protective layer 40, and a third protective layer 50.

[0057] One surface of the polarizer 10, specifically the upper surface of the polarizer 10, may be the light-emitting surface of the polarizer 10 relative to the internal light of the optical display device using the polarizer. Therefore, the first optical functional layer 20 and the first protective layer 30 may be stacked on the light-emitting surface of the polarizer 10 relative to the internal light of the optical display device. However, it should be understood that the invention is not limited thereto, and the first optical functional layer 20 may also be stacked on the light-incident surface of the polarizer 10 relative to the internal light of the optical display device.

[0058] Preferably, the first optical functional layer 20 and the first protective layer 30 are stacked on the light-emitting surface of the polarizer relative to the internal light of the optical display device. In this way, the effects of the present invention can be achieved more easily.

[0059] In this article, "internal light" refers to light emitted from the light source of the backlight unit and propagating through the polarizer.

[0060] First optical functional layer 20

[0061] The first optical functional layer 20 of the polarizing plate can serve as a contrast and / or brightness enhancement layer. Preferably, the first optical functional layer 20 serves as a contrast enhancement layer.

[0062] The upper and lower surfaces of the first optical functional layer 20, i.e., the light-emitting surface and the light-incident surface of the first optical functional layer 20, are substantially completely flat and unpatterned, such as... Figure 1 As shown in the figure. Nevertheless, the first optical functional layer 20 can improve frontal and lateral contrast and / or brightness by containing needle-like particles oriented in the plane of the first optical functional layer, wherein at least one of the needle-like particles has a longitudinal direction forming an orientation angle of -10° to +10° relative to the light absorption axis of the polarizer, and the standard deviation of the orientation angle of the longitudinal direction of the needle-like particles relative to the light absorption axis of the polarizer has a value of 15° or less. Therefore, the polarizer according to the invention is easy to manufacture and reduces thickness by eliminating the need for optical patterns or patterned layers.

[0063] Figure 2 This is a TEM image of needle-like particles according to an embodiment of the present invention. (Reference) Figure 2 The needle-like particles have a predetermined cross-section and a predetermined length. Next, a reference will be used... Figure 3 Describe the needle-like particles in detail.

[0064] refer to Figure 3Each of the needle-like particles is needle-shaped and has a predetermined length L and a predetermined diameter D, wherein the diameter D decreases toward both ends of the needle-like particle, rather than being uniform along the length L. The needle-like particles with non-uniform thickness exhibit optical anisotropy, thereby allowing an incident light beam from the polarizer to propagate in different directions after passing through the needle-like particles.

[0065] Figure 3 The diagram shows needle-like particles with a diameter decreasing towards both ends. However, it should be understood that the invention is not limited thereto, and the needle-like particles according to the invention may have a diameter that is uniform towards one end and decreases towards the other end, depending on the method used to form the needle-like particles.

[0066] Needle-like particles can refer to particles with a length of micrometers. That is, the length L of a needle-like particle is on the micrometer scale. In this document, the expression "with a length of micrometers" means that the length L of the needle-like particle has a value of at least 1 micrometer. Needle-like particles are easily oriented in the desired direction specified herein, and therefore can help improve contrast and brightness. In contrast, needle-like nanoparticles with a length of nanometers are not easily oriented in the desired direction, and therefore it is difficult to achieve the effects of the present invention.

[0067] Preferably, the length L of the needle-like particles is in the range of 10 to 30 micrometers, more preferably 15 to 28 micrometers. Within this range, the needle-like particles can be easily oriented in the desired direction specified herein, thereby contributing to improved contrast and brightness.

[0068] The diameter D of the needle-like particles can range from 0.5 micrometers to 2 micrometers, more precisely from 1 micrometer to 2 micrometers. Within this range, the needle-like particles can provide lateral light diffusion due to their increased aspect ratio.

[0069] The needle-like particles can have an average aspect ratio of 5 to 60, specifically 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, or 60, for example, 10 to 60. Within this range, the needle-like particles can be effective in improving contrast and brightness. Preferably, the needle-like particles have an average aspect ratio of 10 to 50.

[0070] Here, "average aspect ratio" is the average of the aspect ratio measurements of the pointer particles, and the term "aspect ratio" is the ratio of the length of each of the pointer particles to its maximum diameter.

[0071] As described above, the needle-like particles are oriented in the plane of the first optical functional layer. Assuming the light absorption axis of the polarizer is 0°, the orientation angle of the needle-like particles has an average value of -10° to +10° and a standard deviation of 15° or less than 15°. The orientation angle is the angle between the longitudinal direction of the needle-like particles and the light absorption axis of the polarizer.

[0072] The needle-like particles are oriented at a predetermined orientation angle within the plane of the first optical functional layer. Here, the "orientation angle" is the angle between the longitudinal direction of the needle-like particles and the light absorption axis (0°) of the polarizer. Spherical particles that do not have a longitudinal direction do not have an orientation angle.

[0073] According to the present invention, since the orientation angle of the needle-like particles has an average value of -10° to +10° and a standard deviation of 15° or less, the incident light beam from the polarizer can propagate in different directions after passing through the needle-like particles, thereby improving frontal and lateral contrast and brightness. The light absorption axis of the polarizer can be the machine direction (MD) of the polarizer.

[0074] Next, we will refer to Figure 4 and Figure 5A , Figure 5B Describe the mean and standard deviation of the orientation angles.

[0075] Figure 4 This is a schematic diagram showing the distribution of the longitudinal direction of the needle-like particles relative to the orientation angle of the reference when the light absorption axis of the polarizer is assumed to be placed at a 90° angle relative to the reference. Figure 5A This is an image showing the orientation of needle-like particles in a first optical functional layer according to an embodiment of the present invention, and Figure 5B This is a graph showing the distribution of measured values ​​of the longitudinal direction of the needle-like particles in the first optical functional layer relative to a reference orientation angle.

[0076] The average orientation angle of the needle-like particles specified in this document is obtained by calculating the average of the measured orientation angles and then subtracting 90° from the calculated average. For example, when the calculated average is 80°, the average orientation angle minus 90° is -10°, and when the calculated average is 100°, the average orientation angle minus 90° is 10°. The standard deviation of the orientation angle can be determined using typical methods known in the art, such as... Figure 5B The angle is calculated based on the distribution of the measured values ​​shown.

[0077] More precisely, the average value of the orientation angle can be -10°, -9.5°, -9°, -8.5°, -8°, -7.5°, -7°, -6.5°, -6°, -5.5°, -5°, -4.5°, -4°, -3.5°, -3°, -2.5°, -2°, -1.5°, -1°, -0.5°, 0, +0.5°, +1°, +1.5°, +2°, +2.5°, +3°, +3.5°, +4°, +4.5°, +5°, +5.5°, +6°, +6.5°, +7°, +7.5°, +8°, ​​+8.5°, +9°, +9.5°, or +10°, for example, from -4.0° to +4.0°. Furthermore, the standard deviation of the orientation angle can be 0°, 0.5°, 1°, 1.5°, 2°, 2.5°, 3°, 3.5°, 4°, 4.5°, 5°, 5.5°, 6°, 6.5°, 7°, 7.5°, 8°, 8.5°, 9°, 9.5°, 10°, 10.5°, 11°, 11.5°, 12°, 12.5°, 13°, 13.5°, 14°, 14.5°, or 15°, specifically from 0° to 8.5°, and more precisely from 5° to 8.5°. Within these ranges, the polarizing plate can achieve the desired effect according to the invention.

[0078] In one embodiment, at least 90%, for example 95% to 100%, of the needle-like particles can be oriented at orientation angles of -10° and +10°. Within this range, the first optical functional layer can provide uniform contrast and improved visibility.

[0079] The needle-like particles can have a higher refractive index than the resin layer described below. In this way, the polarizing plate according to the invention can further improve side contrast and brightness.

[0080] The refractive index difference between the needle-like particles and the resin layer can be 0.8 or less, specifically 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, or 0.8, more precisely 0.5 or less, and even more precisely 0.15 to 0.25. Within this range, the polarizer can further improve contrast and brightness while improving the optical properties of the resin layer.

[0081] The needle-like microparticles may have a refractive index of 1.5 to 2.2, more precisely 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2.0, 2.05, 2.1, 2.15, or 2.2, more precisely 1.6 to 1.8, and more precisely 1.65 to 1.7. Within this range, the needle-like microparticles may have an appropriate refractive index relative to the resin layer described below, thereby contributing to improved contrast and visibility.

[0082] The needle-like particles may be formed from at least one of the following: metal oxides, such as titanium oxide (e.g., TiO2), zirconium oxide (e.g., ZrO2), and zinc oxide (e.g., ZnO); metal compounds, such as calcium carbonate (CaCO3); boehmite; aluminum borate (e.g., AlBO3); calcium silicate (e.g., CaSiO3, wollastonite); magnesium sulfate (MgSO4); magnesium sulfate hydrate (e.g., MgSO4·7H2O); and potassium titanate (e.g., K2Ti8O). 17 Glass and synthetic resins. Preferably, the needle-like particles are formed of calcium carbonate (CaCO3) to facilitate their preparation and achieve the effects of the present invention.

[0083] Needle-like microparticles can be incorporated into the resin layer described below without surface modification. However, surface modification of the needle-like microparticles can improve the compatibility of the microparticles with the resin layer formed from organic materials described below, as well as improve the dispersibility of the microparticles in the resin layer, thereby improving the optical properties of the first optical functional layer and preventing the aggregation of the microparticles, thus contributing to the effects of the present invention. The needle-like microparticles can undergo surface modification of 50% or more of their entire surface area, for example, 60% to 100% or 60% to 95%. Within this range, the needle-like microparticles can have improved compatibility and dispersibility.

[0084] In one embodiment, the needle-like particles may be surface-modified using at least one selected from silane compounds, surfactants, and oils. Preferably, the needle-like particles are surface-treated with a silane compound having (meth)acryloyloxy or (meth)acrylate groups to achieve good compatibility with and good dispersibility in the matrix of the (meth)acrylate resin layer described below.

[0085] Silane compounds having (meth)acryloyloxy or (meth)acrylate groups may contain at least one selected from 3-(meth)acryloyloxypropylmethyldimethoxysilane, 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, and 3-(meth)acryloyloxypropyltrimethoxysilane, specifically at least one selected from 3-(meth)acryloyloxypropyltrimethoxysilane and 3-(meth)acryloyloxypropyltriethoxysilane.

[0086] The refractive index difference between the surface-modified needle-like particles and the resin layer can be 0.8 or less, specifically 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, or 0.8, more precisely 0.5 or less, and even more precisely 0.15 to 0.25. Within this range, the polarizer can further improve contrast and brightness while improving the optical properties of the resin layer.

[0087] The surface-modified needle-like microparticles may have a refractive index of 1.5 to 2.2, more precisely 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2.0, 2.05, 2.1, 2.15, or 2.2, more precisely 1.6 to 1.8, and even more precisely 1.65 to 1.7. Within this range, the needle-like microparticles may have an appropriate refractive index relative to the resin layer described below, thereby contributing to improved contrast and visibility.

[0088] The needle-like particles may be present in the first optical functional layer in amounts ranging from 1 wt% to 30 wt%, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, or 30 wt%, specifically 4 wt% to 15 wt%. Within this range, the polarizer can achieve improvements in contrast and brightness. If the needle-like particles are present in excess in the first optical functional layer, this can lead to increased haze.

[0089] The needle-like particles may be disposed at the outermost portion of the upper surface of the first optical functional layer or at the outermost portion of the lower surface of the first optical functional layer. Preferably, the needle-like particles are uniformly dispersed in the first optical functional layer, and more specifically, dispersed in the resin layer described below.

[0090] In one embodiment, needle-like microparticles may be impregnated into a resin layer to form a first optical functional layer 20.

[0091] The first optical functional layer 20, specifically the resin layer, may be inserted between the first protective layer 30 and the second protective layer 40, and may also act as an adhesive layer for bonding the first protective layer 30 to the second protective layer 40 in an adhesive manner. However, it should be understood that the invention is not limited thereto, and in embodiments where the second protective layer is omitted, the resin layer may adhesively bond the first protective layer to the polarizer. Alternatively, the first optical functional layer 20, specifically the resin layer, may be a non-adhesive layer.

[0092] The resin layer has a glass transition temperature (Tg) of -70°C to -15°C and a strength of 1×10⁻⁶ at 25°C. -3 From 9×10 MPa -1 Storage modulus in megapascals. Within these ranges of storage modulus at glass transition temperature and 25°C, the first optical functional layer, specifically the resin layer, can have sufficient interlayer peel strength to adhesively bond the first protective layer to the second protective layer (or polarizer). Additionally, within these ranges of storage modulus at glass transition temperature and 25°C, the resin layer can reduce warping of the polarizer caused by different stacking structures on opposite surfaces of the polarizer.

[0093] Specifically, the resin layer can have temperatures of -70℃, -69℃, -68℃, -67℃, -66℃, -65℃, -64℃, -63℃, -62℃, -61℃, -60℃, -59℃, -58℃, -57℃, -56℃, -55℃, -54℃, -53℃, -52℃, -51℃, -50℃, -49℃, -48℃, -47℃, -46℃, -45℃, -44℃, -43℃, -42℃, -41℃, and so on. 40℃, -39℃, -38℃, -37℃, -36℃, -35℃, -34℃, -33℃, -32℃, -31℃, -30℃, -29℃, -28℃, -27℃, -26℃, -25℃, -24℃, -23℃, -22℃, -21℃, -20℃, -19℃, -18℃, -17℃, -16℃ or -15℃, more precisely -65℃ to -15℃, and 1×10 at 25℃ -3 Megapascals, 2×10 -3 Megapascals, 3×10 -3 Megapascals, 4×10 -3 Megapascals, 5×10 -3 Megapascals, 6×10 -3 Megapascals, 7×10 -3 Megapascals, 8×10 -3 Megapascals, 9×10 -3 Megapascals, 1×10 -2 Megapascals, 2×10 -2 Megapascals, 3×10 -2 Megapascals, 4×10-2 Megapascals, 5×10 -2 Megapascals, 6×10 -2 Megapascals, 7×10 -2 Megapascals, 8×10 -2 Megapascals, 9×10 -2 Megapascals, 1×10 -1 Megapascals, 2×10 -1 Megapascals, 3×10 -1 Megapascals, 4×10 -1 Megapascals, 5×10 -1 Megapascals, 6×10 -1 Megapascals, 7×10 -1 Megapascals, 8×10 -1 Megapascals or 9×10 -1 Megapascals, or more precisely 1×10 -2 From 5×10 MPa -1 Megapascals or 1×10 -1 From 5×10 MPa -1 Megapascal energy storage modulus.

[0094] In one embodiment, as measured with respect to the PET film, the first optical functional layer may have a peel strength of 600 g / 25 mm or greater, specifically 600 g / 25 mm, 650 g / 25 mm, 700 g / 25 mm, 750 g / 25 mm, 800 g / 25 mm, 850 g / 25 mm, or 900 g / 25 mm, for example, a peel strength from 600 g / 25 mm to 900 g / 25 mm. Within this range, the polarizer can exhibit good characteristics in terms of reliability and anti-delamination.

[0095] The resin layer can be formed from a resin layer composition comprising a resin capable of achieving a specified glass transition temperature and a storage modulus range at 25°C while also possessing adhesive properties. Preferably, the resin comprises a non-birefringent resin so as not to adversely affect the improvement of the contrast and brightness of the needle-like particles. Therefore, the resin layer may also be non-birefringent. For example, the resin may comprise (meth)acrylate resins and polyester resins, specifically (meth)acrylate resins.

[0096] In one embodiment, the resin layer may be formed from a resin layer composition comprising a thermosetting resin.

[0097] In one embodiment, the resin layer may be formed from a composition for thermosetting resin layers.

[0098] The specified glass transition temperature and storage modulus range at 25°C of the resin layer can be implemented by typical methods known to those skilled in the art. For example, the specified glass transition temperature and storage modulus range at 25°C of the resin layer can be implemented by adjusting the glass transition temperature of the resin, the amount of curing agent, and the type and / or amount of monomers as described below.

[0099] The resin layer can have a refractive index of 1.4 to 1.6, more precisely 1.4, 1.43, 1.45, 1.47, 1.49, 1.5, 1.53, 1.55, 1.57, 1.59, or 1.6, more precisely 1.45 to 1.57, and even more precisely 1.47 to 1.50. Within this range, the polarizer can further improve contrast and brightness.

[0100] Next, a resin layer composition comprising (meth)acrylate resin will be described.

[0101] (Meth)acrylate resins may be formed from a mixture of monomers comprising: alkyl-containing (meth)acrylate monomers; and (meth)acrylate monomers containing crosslinkable functional groups, including at least one selected from hydroxyl-containing (meth)acrylate monomers, carboxyl-containing (meth)acrylate monomers, amino-containing (meth)acrylate monomers, alicyclic (meth)acrylate monomers, and heterocyclic (meth)acrylate monomers.

[0102] Alkyl-containing (meth)acrylic acid monomers may contain unsubstituted C1 to C2 groups. 10 Alkyl (meth)acrylates. Specifically, alkyl-containing (meth)acrylate monomers may include at least one selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, and decyl (meth)acrylate, but are not limited thereto. These may be used alone or in mixtures thereof.

[0103] Hydroxyl-containing (meth)acrylic acid monomers may contain at least one selected from the group consisting of C1 to C2. 20 (Meth)acrylic acid monomers with alkyl groups and at least one hydroxyl group, having C3 to C4 20 (Meth)acrylic acid monomers with cycloalkyl groups and at least one hydroxyl group, and having C6 to C6 atoms. 20 A (meth)acrylic acid monomer with an aromatic group and at least one hydroxyl group. Specifically, the hydroxyl-containing (meth)acrylic acid monomer has a C1 to C2 group. 20An alkyl group and at least one hydroxyl group of (meth)acrylic acid monomers, and may contain at least one selected from 2-hydroxyethyl (meth)acrylic acid, 2-hydroxypropyl (meth)acrylic acid, 2-hydroxybutyl (meth)acrylic acid, 4-hydroxybutyl (meth)acrylic acid, 6-hydroxyhexyl (meth)acrylic acid, and 1-chloro-2-hydroxypropyl (meth)acrylic acid. These may be used alone or in mixtures thereof.

[0104] Carboxyl-containing (meth)acrylic acid monomers may contain (meth)acrylic acid.

[0105] Amino-containing (meth)acrylic acid monomers may include aminoalkyl (meth)acrylic acid esters.

[0106] (Meth)acrylate resins can be prepared from monomer mixtures by typical polymerization methods known to those skilled in the art. For example, (meth)acrylate resins can be prepared by solution polymerization, suspension polymerization, etc.

[0107] (Meth)acrylate resins can have a glass transition temperature ranging from -70°C to -15°C, more precisely -65°C to -15°C. Within this range, a specified glass transition temperature for the resin layer can be easily achieved.

[0108] The resin layer composition may further include a curing agent for a curable resin. The curing agent allows the resin layer to have adhesive properties while allowing for easy implementation of the specified glass transition temperature and storage modulus at 25°C.

[0109] The curing agent may contain at least one selected from isocyanate curing agents, epoxy curing agents, aziridine curing agents, carbodiimide curing agents, and metal chelate curing agents.

[0110] Isocyanate curing agents may contain bifunctional or higher functionalities, such as bifunctional to hexafunctional isocyanate curing agents. Specifically, isocyanate curing agents may include: alicyclic isocyanate curing agents, such as isophorone diisocyanate (IPDI); trifunctional isocyanate curing agents, such as trifunctional trimethylolpropane-modified toluene diisocyanate adducts, trifunctional toluene diisocyanate trimers, and trimethylolpropane-modified xylene diisocyanate adducts; hexafunctional trimethylolpropane-modified toluene diisocyanate; and hexafunctional isocyanurate-modified toluene diisocyanate. Preferably, alicyclic isocyanate curing agents are used as isocyanate curing agents to help adjust the refractive index of the resin layer.

[0111] The curing agent can be 0.1 to 10 parts by weight relative to 100 parts by weight of (meth)acrylate resin, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8 parts by weight. The resin layer is present in amounts ranging from 0.2 parts by weight to 5 parts by weight, specifically 2.9 parts by weight, 3 parts by weight, 3.1 parts by weight, 3.2 parts by weight, 3.3 parts by weight, 3.4 parts by weight, 3.5 parts by weight, 3.6 parts by weight, 3.7 parts by weight, 3.8 parts by weight, 3.9 parts by weight, 4 parts by weight, 4.1 parts by weight, 4.2 parts by weight, 4.3 parts by weight, 4.4 parts by weight, 4.5 parts by weight, 4.6 parts by weight, 4.7 parts by weight, 4.8 parts by weight, 4.9 parts by weight, 5 parts by weight, 5.5 parts by weight, 6 parts by weight, 6.5 parts by weight, 7 parts by weight, 7.5 parts by weight, 8 parts by weight, 8.5 parts by weight, 9 parts by weight, 9.5 parts by weight, and 10 parts by weight. Within this range, the resin layer readily possesses adhesive properties.

[0112] In addition to (meth)acrylate resin and curing agent, the resin layer composition may further contain various additives.

[0113] In one embodiment, the resin layer composition may further comprise a dispersant to promote the dispersion of needle-like particles. The dispersant may comprise, but is not limited to, typical dispersants known to those skilled in the art, such as, DISPERBYK 180 (an alkyl alkoxide ammonium salt of a copolymer having an acidic group) or dispersants of the same series.

[0114] The first optical functional layer 20 may have a thickness of 100 micrometers or less, specifically 5 micrometers, 10 micrometers, 15 micrometers, 20 micrometers, 25 micrometers, 30 micrometers, 35 micrometers, 40 micrometers, 45 micrometers, 50 micrometers, 55 micrometers, 60 micrometers, 65 micrometers, 70 micrometers, 75 micrometers, 80 micrometers, 85 micrometers, 90 micrometers, 95 micrometers, or 100 micrometers, preferably less than 50 micrometers, more specifically 5 micrometers to 15 micrometers. Within this range, the required hardness of the polarizing plate can be ensured.

[0115] The first optical functional layer 20 may have a light transmittance of 90% or greater, specifically 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, specifically 90% to 100%. The first optical functional layer 20 may have a haze of 30% or less, specifically 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%, specifically 0% to 30%, more specifically 10% to 25%. Within these ranges of light transmittance and haze, the first optical functional layer 20 can be used in a polarizing plate and can help improve contrast and brightness by reducing turbidity.

[0116] The first optical functional layer 20 can be formed by the method described below.

[0117] In one embodiment, the first optical functional layer 20 may be formed as a coating on the first protective layer 30. The first optical functional layer 20 may be formed by slot die coating, microgravure printing coating, gap roller coating, or bar coating. Specifically, the orientation angle and standard deviation of the needle-like particles specified herein may be implemented, but is not limited to, adjusting the viscosity of the composition for the first optical functional layer during composition formation (e.g., adjusting to 100 to 400 centipoise at 25°C) or adjusting the coating pressure (e.g., adjusting to 0.1 to 0.4 MPa at 25°C) during the application of the first optical functional layer 20 onto the first protective layer 30. Here, the composition for the first optical functional layer may be prepared by incorporating the needle-like particles into the resin layer composition.

[0118] refer to Figure 6 According to the present invention, the polarizing plate may further include a second optical functional layer 60, which is stacked on the upper surface of the first optical functional layer 20, that is, the light emitting surface of the first optical functional layer 20 relative to the internal light emitting surface of the optical display device.

[0119] The second optical functional layer 60 may include: a resin layer; and needle-like particles. Utilizing the second optical functional layer 60, the polarizer according to the present invention can further improve vertical and lateral visibility.

[0120] The needle-like particles may have the same length L, diameter D, and aspect ratio as the needle-like particles in the first optical functional layer 20. Furthermore, the refractive index difference between the needle-like particles and the resin layer, the range of the refractive index of the needle-like particles, and the amount of needle-like particles in the second optical functional layer may be the same as described regarding the needle-like particles in the first optical functional layer 20.

[0121] Furthermore, the needle-like particles of the second optical functional layer 60 may have a longitudinal direction that is substantially orthogonal to the longitudinal direction of the needle-like particles of the first optical functional layer 20. In this way, the polarizer according to the invention can further improve light diffusion in both the vertical and horizontal directions. Here, "substantially orthogonal" means that the longitudinal direction of the needle-like particles of the second optical functional layer 60 forms an angle of 85° to 95°, specifically 90°, relative to the longitudinal direction of the needle-like particles of the first optical functional layer 20.

[0122] The resin layer of the second optical functional layer 60 may have the same glass transition temperature and storage modulus at 25°C as the resin layer of the first optical functional layer 20, and may be formed from a composition substantially the same as the resin layer of the first optical functional layer 20.

[0123] In addition, the second optical functional layer 60 may have the thickness range described in the first optical functional layer 20.

[0124] First protective layer 30

[0125] The first protective layer 30 can be stacked relative to the internal light of the optical display device on the light emitting surface of the first optical functional layer 20, and can support the first optical functional layer 20.

[0126] The first protective layer 30 may have a light transmittance of 90% or greater, for example, 90% to 100%. Within this range, the first protective layer 30 may transmit incident light passing through it without affecting the incident light.

[0127] The first protective layer 30 may comprise a transparent substrate material. The transparent substrate material may have a different refractive index than the first optical functional layer 20. The transparent substrate material may have a higher or lower refractive index than the first optical functional layer 20. Preferably, the transparent substrate material has a higher refractive index than the resin forming the first optical functional layer 20. In this way, the transparent substrate material can help improve contrast and brightness.

[0128] The transparent substrate material may comprise an optically transparent resin film having: a light incident surface; and a light emitting surface opposite to the light incident surface. The transparent substrate material may consist of a single layer of optically transparent resin film. However, it should be understood that the present invention is not limited thereto, and the transparent substrate material may consist of multiple layers of optically transparent resin films. The optically transparent resin film may comprise at least one selected from the following: cellulose ester resins including triacetylcellulose (TAC), cyclic polyolefin resins including amorphous cyclic polyolefins (COP), polycarbonate resins, polyester resins including polyethylene terephthalate (PET), polyethersulfone resins, polysulfone resins, polyamide resins, polyimide resins, non-cyclic polyolefin resins, polyacrylate resins including poly(methyl methacrylate) resins, polyvinyl alcohol resins, polyvinyl chloride resins, and polyvinylidene chloride resins, but is not limited thereto. Preferably, the transparent substrate material comprises a polyester resin, which includes polyethylene terephthalate (PET) and the like to further improve contrast and brightness.

[0129] Although the transparent substrate material may be an unstretched film, it should be understood that the present invention is not limited thereto, and the transparent substrate material may be a retardation film or an isotropic optical film, which is obtained by stretching resin using a predetermined method and has a certain range of retardation.

[0130] In one embodiment, the transparent substrate material may be an isotropic optical film having a Re value of 0 nm to 60 nm, specifically 40 nm to 60 nm. Within this range, the transparent substrate material can provide good image quality by compensating for the viewing angle. Here, "isotropic optical film" means a film in which nx, ny, and nz (nz being the out-of-plane refractive index at a wavelength of 550 nm) have substantially the same values. The expression "substantially the same" here includes not only the case where nx, ny, and nz have exactly the same values, but also the case where nx, ny, and nz have values ​​that are not significantly different.

[0131] In another embodiment, the transparent substrate material may be a retardation film having a Rere of 60 nm or greater. For example, the transparent substrate material may have a Rere of 60 nm to 500 nm or 60 nm to 300 nm. For example, the transparent substrate material may have a Rere of 6,000 nm or greater, 8,000 nm or greater, more precisely 10,000 nm or greater, more precisely greater than 10,000 nm, and even more precisely 10,100 nm to 30,000 nm or 10,100 nm to 15,000 nm. Within this range, the transparent substrate material can prevent the occurrence of moiré patterns while further enhancing the contrast and visibility of light diffused through the first resin layer.

[0132] The transparent substrate material can have a haze of 30% or less, specifically 2% to 30%. Within this range, the transparent substrate material can be used in polarizing plates.

[0133] Transparent substrate materials can have thicknesses ranging from 5 micrometers to 200 micrometers, for example, from 30 micrometers to 120 micrometers. Within this range, transparent substrate materials can be used in polarizing plates.

[0134] In addition to the transparent substrate material, the first protective layer 30 may further include a functional layer stacked on at least one surface of the transparent substrate material. The functional layer may include at least one selected from hard coating, scattering layer, low reflectivity layer, ultra-low reflectivity layer, base coating, fingerprint-resistant layer, anti-reflective layer, and anti-glare layer.

[0135] Preferably, the first protective layer 30 includes an anti-reflective layer as a functional layer. Here, the first protective layer 30 may have a reflectance of 5% or less, specifically 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, for example, from 0.1% to 3%, for example, 0.2% or less. Within this range, the effects of the invention can be more easily achieved. Here, the "reflectance" can be measured using typical methods known to those skilled in the art.

[0136] The first protective layer 30 may have a haze of 30% or less, specifically 1% to 30%, or 2% to 20%. Within this range, the first protective layer 30 can be used in a polarizing plate and can help improve contrast and brightness by reducing haze.

[0137] The laminate of the first optical functional layer 20 and the first protective layer 30 may have a haze of 30% or less, specifically 0%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%, for example, 1% to 30% or 2% to 20%. Within this range, the laminate of the first optical functional layer 20 and the first protective layer 30 can be used in a polarizing plate and can help improve contrast and visibility by reducing turbidity.

[0138] Polarizing film 10

[0139] The polarizer 10 is used to polarize incident light from the liquid crystal panel and transmit the polarized light to the first optical functional layer 20. The polarizer 10 can be stacked relative to the light incident surface of the first optical functional layer 20 relative to the internal light of the optical display device.

[0140] The polarizer 10 may comprise a polyvinyl alcohol polarizer prepared by uniaxial stretching of a polyvinyl alcohol film.

[0141] The polarizer 10 can have a thickness of about 5 micrometers to about 40 micrometers. Within this range, the polarizer can be used in optical display devices.

[0142] Second protective layer 40

[0143] The second protective layer 40 can be stacked on the light incident surface of the polarizer 10 relative to the internal light of the optical display device. That is, the second protective layer 40 can be inserted between the polarizer 10 and the first optical functional layer 20. However, it should be understood that the present invention is not limited thereto, and the second protective layer 40 may be omitted.

[0144] The second protective layer 40 may have a light transmittance of 90% or greater, for example, 90% to 100%. Within this range, the second protective layer 40 may transmit incident light passing through it without affecting the incident light.

[0145] The second protective layer 40 may comprise a transparent substrate material. The transparent substrate material may comprise an optically transparent resin film having: a light incident surface; and a light emitting surface opposite the light incident surface. The transparent substrate material may consist of a single layer of optically transparent resin film. However, it should be understood that the present invention is not limited thereto, and the transparent substrate material may consist of multiple layers of optically transparent resin films. The optically transparent resin film may comprise at least one selected from the following: cellulose ester resins including triacetyl cellulose (TAC), cyclic polyolefin resins including amorphous cyclic polyolefins (COP), polycarbonate resins, polyester resins including polyethylene terephthalate (PET), polyethersulfone resins, polysulfone resins, polyamide resins, polyimide resins, non-cyclic polyolefin resins, polyacrylate resins including poly(methyl methacrylate) resins, polyvinyl alcohol resins, polyvinyl chloride resins, and polyvinylidene chloride resins, but is not limited thereto. Preferably, the transparent substrate material comprises a cyclic polyolefin resin, wherein the cyclic polyolefin resin comprises amorphous cyclic polyolefin (COP) or the like.

[0146] Although the transparent substrate material may be an unstretched film, it should be understood that the present invention is not limited thereto, and the transparent substrate material may be a retardation film or an isotropic optical film, which is obtained by stretching resin using a predetermined method and has a certain range of retardation.

[0147] In one embodiment, the transparent substrate material may be an isotropic optical film having a Re value of 0 nm to 60 nm, specifically 40 nm to 60 nm. Within this range, the transparent substrate material can provide good image quality by compensating for the viewing angle. Here, "isotropic optical film" means a film in which nx, ny, and nz (nz being the out-of-plane refractive index at a wavelength of 550 nm) have substantially the same values. The expression "substantially the same" here includes not only the case where nx, ny, and nz have exactly the same values, but also the case where nx, ny, and nz have values ​​that are not significantly different.

[0148] In another embodiment, the transparent substrate material may be a retardation film having a Rere of 60 nm or greater. For example, the transparent substrate material may have a Rere of 60 nm to 500 nm or 60 nm to 300 nm. For example, the transparent substrate material may have a Rere of 6,000 nm or greater, 8,000 nm or greater, more precisely 10,000 nm or greater, more precisely greater than 10,000 nm, and even more precisely 10,100 nm to 30,000 nm or 10,100 nm to 15,000 nm. Within this range, the transparent substrate material can prevent the appearance of moiré patterns while further enhancing the contrast and visibility of light diffused through the first resin layer.

[0149] The second protective layer 40, specifically a transparent substrate material, may have a thickness of 5 micrometers to 200 micrometers, for example, 30 micrometers to 120 micrometers. Within this range, the second protective layer 40 can be used in polarizing plates.

[0150] As described above, the second protective layer 40 can be omitted from the polarizing plate according to the present invention.

[0151] Third protective layer 50

[0152] The third protective layer 50 can be stacked on the light incident surface of the polarizer 10 relative to the internal light of the optical display device.

[0153] The third protective layer 50 may have a light transmittance of 90% or greater, for example, 90% to 100%. Within this range, the third protective layer 50 may transmit incident light that passes through it without affecting the incident light.

[0154] The third protective layer 50 may comprise a transparent substrate material. The transparent substrate material may comprise an optically transparent resin film having: a light incident surface; and a light emitting surface opposite the light incident surface. The transparent substrate material may consist of a single layer of optically transparent resin film. However, it should be understood that the present invention is not limited thereto, and the transparent substrate material may consist of multiple layers of optically transparent resin films. The optically transparent resin film may comprise at least one selected from the following: cellulose ester resins including triacetyl cellulose (TAC), cyclic polyolefin resins including amorphous cyclic polyolefins (COP), polycarbonate resins, polyester resins including polyethylene terephthalate (PET), polyethersulfone resins, polysulfone resins, polyamide resins, polyimide resins, non-cyclic polyolefin resins, polyacrylate resins including poly(methyl methacrylate) resins, polyvinyl alcohol resins, polyvinyl chloride resins, and polyvinylidene chloride resins, but is not limited thereto. Preferably, the transparent substrate material comprises a cyclic polyolefin resin, wherein the cyclic polyolefin resin comprises amorphous cyclic polyolefin (COP) or the like.

[0155] Although the transparent substrate material may be an unstretched film, it should be understood that the present invention is not limited thereto, and the transparent substrate material may be a retardation film or an isotropic optical film, which is obtained by stretching resin using a predetermined method and has a certain range of retardation.

[0156] In one embodiment, the transparent substrate material may be an isotropic optical film having a Re value of 0 nm to 60 nm, specifically 40 nm to 60 nm. Within this range, the transparent substrate material can provide good image quality by compensating for the viewing angle. Here, "isotropic optical film" means a film in which nx, ny, and nz (nz being the out-of-plane refractive index at a wavelength of 550 nm) have substantially the same values. The expression "substantially the same" here includes not only the case where nx, ny, and nz have exactly the same values, but also the case where nx, ny, and nz have values ​​that are not significantly different.

[0157] In another embodiment, the transparent substrate material may be a retardation film having a Rere of 60 nm or greater. For example, the transparent substrate material may have a Rere of 60 nm to 500 nm or 60 nm to 300 nm. For example, the transparent substrate material may have a Rere of 6,000 nm or greater, 8,000 nm or greater, more precisely 10,000 nm or greater, more precisely greater than 10,000 nm, and even more precisely 10,100 nm to 30,000 nm or 10,100 nm to 15,000 nm. Within this range, the transparent substrate material can prevent the appearance of moiré patterns while further enhancing the contrast and visibility of light diffused through the first resin layer.

[0158] The third protective layer 50, specifically a transparent substrate material, may have a thickness ranging from 5 micrometers to 200 micrometers, for example, from 30 micrometers to 120 micrometers. Within this range, the third protective layer 50 can be used in polarizing plates.

[0159] The third protective layer 50 can be omitted from the polarizing plate according to the present invention.

[0160] The optical display device according to the present invention includes a polarizing plate according to the present invention.

[0161] In one embodiment, the optical display device may include a polarizing plate as a viewer-side polarizing plate. Here, "viewer-side polarizing plate" refers to a polarizing plate disposed on the side of the screen of the optical display device relative to the liquid crystal panel, that is, a polarizing plate disposed opposite to the light source of the optical display device.

[0162] In one embodiment, a liquid crystal display may include a light-concentrating backlight unit, a light source-side polarizing plate, a liquid crystal panel, and a viewer-side polarizing plate stacked in sequence, wherein the viewer-side polarizing plate may include a polarizing plate according to the present invention. Here, "light source-side polarizing plate" refers to a polarizing plate disposed on the light source side of an optical display device. The liquid crystal panel may employ vertical alignment (VA) mode, IPS mode, patterned vertical alignment (PVA) mode, or super-patterned vertical alignment (S-PVA) mode, but is not limited thereto.

[0163] The invention will now be described in more detail with reference to some examples. However, it should be noted that these examples are provided for illustrative purposes only and should not be construed as limiting the invention in any way.

[0164] Example 1

[0165] (1) A polyethylene terephthalate (PET) film (DSG-17(Z)PET80, DNP Co., Ltd., with an anti-reflection layer formed on its upper surface, was prepared. The reflectance was 0.2%.

[0166] As needle-like particles, a mixture of CaCO3 particles (Whiscal A, MARUOCALCIUM Co., Ltd., length: 10 μm to 30 μm, diameter: 0.5 μm to 2.0 μm, refractive index: 1.68) was prepared and added to a methyl ethyl ketone solution containing 3-methacryloyloxypropyltrimethoxysilane (KBM503), and then reacted at room temperature to surface modify the CaCO3 particles containing 3-methacryloyloxypropyltrimethoxysilane.

[0167] Next, methyl ethyl ketone and surface-modified CaCO3 particles were added to the adhesive resin (SAIDEN Chemical Industry Co., Ltd.), and dispersed using a homogenizer for 4 hours. Then, isophorone diisocyanate was added at a rate of 0.2 parts by weight relative to 100 parts by weight of the adhesive resin, followed by stirring at 500 rpm for 15 minutes to prepare the resin layer composition. Subsequently, needle-shaped CaCO3 particles were incorporated into the resin layer composition to prepare a composition for the first optical functional layer.

[0168] The composition for the first optical functional layer is applied to the lower surface of a polyethylene terephthalate (PET) film (the lower surface having an undercoat formed thereon) using a coater, and then dried and heat-cured in a drying oven at 90°C for 4 minutes to form the first optical functional layer (refractive index of surface-modified CaCO3 particles: 1.68, refractive index of resin layer: 1.47, surface-modified CaCO3 particles oriented in resin layer).

[0169] (2) A polarizer (thickness: 13 micrometers, light transmittance: 44%) was prepared by stretching a polyvinyl alcohol film to 3 times its initial length at 60°C, adsorbing iodine onto the stretched film, and further stretching the film to 2.5 times its initial length in a boric acid aqueous solution at 40°C.

[0170] A polyethylene terephthalate (PET) film (Toyobo, Co., Ltd., thickness: 80 micrometers) is bonded to the upper surface of the prepared polarizer, and then a cyclic olefin polymer (COP) film (ZEON Co., Ltd.) is bonded to the lower surface of the polarizer, thereby forming a laminate of PET film, polarizer and COP film.

[0171] (3) A polarizing plate is fabricated by laminating a first optical functional layer onto a PET film of a laminate, wherein a PET film with an anti-reflective layer (first protective layer), a first optical functional layer, a PET film (second protective layer), a polarizer, and a COP film (third protective layer) are stacked thereon in the order stated. CaCO3 particles are oriented in the plane of the first optical functional layer, wherein the orientation angle of the CaCO3 particles has an average value of +1.2° and a standard deviation of 7.2°.

[0172] Example 2

[0173] Except for the changes to the configuration of the first optical functional layer as listed in Table 1, the polarizing plate is manufactured in the same manner as in Example 1.

[0174] Example 3

[0175] The polarizing plate was manufactured in the same manner as in Example 1, except that a different adhesive resin was used instead of the adhesive resin from Saiden Chemical Industries Ltd. and the configuration of the first optical functional layer was changed as listed in Table 1.

[0176] Example 4

[0177] Except for the changes to the configuration of the first optical functional layer as listed in Table 1, the polarizing plate is manufactured in the same manner as in Example 1.

[0178] Example 5 to Example 6

[0179] Except for the changes to the configuration of the first optical functional layer as listed in Table 1, the polarizing plate is manufactured in the same manner as in Example 1.

[0180] Example 7

[0181] As needle-like microparticles, a mixture of CaCO3 particles (Whiscal A, Maruo Calcium Co., Ltd., length: 10 to 30 micrometers, diameter: 0.5 to 2.0 micrometers, refractive index: 1.68) was prepared and added to a methyl ethyl ketone solution containing a dispersant (Dispic 180, an alkyl ammonium salt of a copolymer with acidic groups), followed by stirring at 1,000 rpm and room temperature for 2 hours. Next, a composition for the first optical functional layer was prepared using the adhesive resin and curing agent as in Example 1, and subsequently, a polarizing plate was manufactured in the same manner as in Example 1.

[0182] Comparative Example 1

[0183] The polarizing plate was manufactured in the same manner as in Example 1, except that an adhesive resin (PHS210, Nippon Synthetic Chemical Industry Co., Ltd.) was used instead of an adhesive resin (Saiden Chemical Industry Co., Ltd.).

[0184] Comparative Example 2

[0185] The polarizing plate was manufactured in the same manner as in Example 1, except that an adhesive resin (982-S8, Saiden Chemical Industries Ltd.) was used instead of an adhesive resin (Saiden Chemical Industries Ltd.).

[0186] Comparative Example 3

[0187] The polarizing plate was manufactured in the same manner as in Example 1, except that isotropic spherical particles (MSP080 silicone beads, Nikko Rica Corporation, diameter: 0.8 micrometers) were used instead of CaCO3 particles.

[0188] Comparative Example 4

[0189] Except for the changes to the configuration of the first optical functional layer as listed in Table 1, the polarizing plate is manufactured in the same manner as in Example 1.

[0190] Reference Example 1

[0191] Except for omitting the first optical functional layer, the polarizing plate is manufactured in the same manner as in Example 1. That is, the polarizing plate has a structure in which a PET film, a polarizer, and a COP film are stacked in the order stated.

[0192] Using each of the polarizing plates manufactured in the examples and comparative examples, a model for measuring the viewing angle was made, and then evaluated according to the characteristics shown in Table 1.

[0193] Light source side polarizer

[0194] A polarizing film was prepared by stretching a polyvinyl alcohol film to three times its initial length at 60°C, adsorbing iodine onto the stretched film, and then further stretching the film to 2.5 times its initial length in a boric acid aqueous solution at 40°C. Next, a triacetyl cellulose film (thickness: 80 micrometers) serving as a base layer was bonded to both surfaces of the polarizing film using a polarizing plate adhesive (Z-200, Nippon Synthetic Chemicals Co., Ltd.), thereby manufacturing the polarizing plate. The manufactured polarizing plate is a light source-side polarizing plate.

[0195] Viewer-side polarizer

[0196] Each of the polarizing plates manufactured in the examples and comparative examples is used as a viewer-side polarizing plate.

[0197] Module for LCD displays

[0198] A light source-side polarizing plate is adhesively bonded to the lower surface of the liquid crystal panel (PVA liquid crystal mode), and then a viewer-side polarizing plate is adhesively bonded to the upper surface of the liquid crystal panel, wherein the anti-reflective layer of the viewer-side polarizing plate is placed furthest from the upper surface of the liquid crystal panel. Subsequently, a backlight unit is placed under the light source-side polarizing plate, thereby manufacturing a module for a liquid crystal display.

[0199] Each of the polarizing plates manufactured in the examples and comparative examples was evaluated for the following physical properties. The results are shown in Table 1.

[0200] (1) Storage modulus of resin layer (unit: megapascal): Each of the resin layer compositions of the examples and comparative examples was applied to a release film to a dried thickness of 50 micrometers, and then dried at 95°C for 4 minutes to form a resin layer. Multiple resin layers prepared as described above were stacked one after another to a thickness of 500 micrometers and then cut into circles with a diameter of 8 mm to prepare samples. The storage modulus of the prepared samples at 25°C was measured using a storage modulus measuring instrument (Advanced Rheology Measurement Extension System, TA Instruments) at a heating rate of 10°C / min and a temperature range of 0°C to 100°C.

[0201] (2) Glass transition temperature of the resin layer (unit: °C): The resin layer was formed in the same manner as in (1), and a 15 mg resin layer sample was then prepared (on a 6 mm Al disk). The sample was then heated to 180 °C at a heating rate of 20 °C / min in a nitrogen atmosphere (50 mL / min), cooled to -100 °C, and simultaneously heated to 100 °C at a heating rate of 10 °C / min while measuring the glass transition temperature of the prepared sample. Here, the glass transition temperature was measured using a Discovery Hybrid Rheometer (TA Instruments).

[0202] (3) Contrast Ratio and Relative Contrast Ratio (unit: %): Each of the LED light source, light guide plate, and module for the liquid crystal display is assembled into a liquid crystal display containing a single-sided LED light source (except for the module for the liquid crystal display manufactured using each of the polarizing plates manufactured in the examples and comparative examples, the liquid crystal display has the same configuration as a Samsung TV (55-inch UHD TV, model: UN55KS8000F)). The contrast ratio of the liquid crystal display is measured from the side (corresponding to the point (0°, 60°) in the spherical coordinate system) using an EZCONTRAST X88RC (EZXL-176R-F422A4, ELDIM SA). Here, the contrast ratio is calculated by the ratio of brightness in white mode to brightness in black mode. In addition, the relative contrast ratio is calculated according to the following formula: Relative contrast ratio = {(contrast ratio of each of the liquid crystal displays in the examples, comparative examples, and reference example 1) / (contrast ratio of reference example 1)} × 100. A relative contrast of more than 100%, or more precisely, more than or equal to 115%, is considered preferred.

[0203] (4) Pencil hardness: Each of the polarizing plates manufactured in the examples and comparative examples was laminated onto a glass plate, and then the pencil hardness of the anti-reflective layer was measured on the surface of the anti-reflective layer using a pencil hardness tester (CT-PC2, Coatech Ltd.) according to ASTM D3502.

[0204] (5) Peel strength (unit: grams / 25 mm): Each of the polarizing plates manufactured in the examples and comparative examples was cut into 150 mm × 25 mm (MD × TD of the polarizer) pieces and then laminated onto a glass plate with an acrylic adhesive layer to prepare samples. The peel strength between the first and second protective layers was then measured using a peel strength measuring instrument (TA-XT Plus texture analyzer, Stable Micro System Ltd.). Here, the peel strength was measured at a peel temperature of 25°C, a peel angle of 180°, and a peel rate of 300 mm / min.

[0205] 6) Mean and standard deviation of orientation angles: The compositions for the first optical functional layer prepared in the examples and comparative examples were coated onto a PET film at a rate of 6 m / min using a coater, and then dried at 90°C for 4 minutes to form the first optical functional layer. Next, a surface image of the first optical functional layer was captured using an optical microscope (Olympus MX61L, magnification: 500×(10×50)), the height of which was adjusted to focus on the surface of the first optical functional layer. The FIJI procedure (method: Fourier components, N bis: 90°, histogram start: 0°, histogram end: 180°) was then performed to obtain the mean and standard deviation of the orientation angles of the particles in the first optical functional layer.

[0206] Table 1

[0207]

[0208] As shown in Table 1, although it does not contain an optical pattern or a patterned layer containing an optical pattern, the polarizing plate according to the present invention provides improved contrast compared to the polarizing plate of Reference Example 1, which does not contain an optical functional layer according to the present invention. Furthermore, compared to the polarizing plate of Comparative Example 3 (containing spherical microparticles) and the polarizing plate of Comparative Example 4 (where the average orientation angle is outside the range specified herein), the polarizing plate according to the present invention provides improved contrast. Moreover, compared to the polarizing plates of Comparative Example 1 and Comparative Example 2, the polarizing plate according to the present invention exhibits good interlayer peel strength and reliability.

[0209] Conversely, the polarizing plates of the comparative examples that do not meet the requirements specified herein do not provide all the advantageous effects of the present invention.

[0210] It should be understood that those skilled in the art can make various modifications, alterations, changes, and equivalent embodiments without departing from the spirit and scope of the invention.

Claims

1. A viewer-side polarizing plate, comprising: Polarizing film; as well as A first optical functional layer and a first protective layer are sequentially stacked on one surface of the polarizer. The first optical functional layer includes: a resin layer; and needle-like microparticles. The resin layer has a glass transition temperature (Tg) of -70°C to -15°C and a strength of 1×10⁻⁶ at 25°C. -3 From 9×10 MPa -1 The energy storage modulus of megapascals, and The needle-like particles are oriented in the plane of the first optical functional layer, and when the light absorption axis of the polarizer is 0°, the orientation angle of the longitudinal direction of the needle-like particles relative to the light absorption axis of the polarizer has an average value of -10° to +10° and a standard deviation of 15° or less than 15°. The needle-like particles have a higher refractive index than the resin layer, with a difference of 0.15 to 0.

25.

2. The viewer-side polarizing plate according to claim 1, wherein the first optical functional layer is a contrast or brightness enhancement layer.

3. The viewer-side polarizing plate of claim 1, wherein the needle-like particles have an average aspect ratio of 5 to 60.

4. The viewer-side polarizing plate of claim 1, wherein the needle-like particles have a length of 10 micrometers to 30 micrometers and a diameter of 0.5 micrometers to 2 micrometers.

5. The viewer-side polarizing plate according to claim 1, wherein the needle-like particles comprise particles formed from at least one selected from titanium dioxide, zirconium oxide, zinc oxide, calcium carbonate, boehmite, aluminum borate, calcium silicate, magnesium sulfate, magnesium sulfate hydrate, potassium titanate, glass, and synthetic resin.

6. The viewer-side polarizing plate of claim 1, wherein the surface of the needle-like particles is modified.

7. The viewer-side polarizing plate of claim 6, wherein the surface of the needle-like particles is modified with at least one selected from silane coupling agents, surfactants, and oils.

8. The viewer-side polarizer of claim 1, wherein the needle-like particles are present in the first optical functional layer in an amount of 1% to 30% by weight.

9. The viewer-side polarizing plate according to claim 1, wherein the resin layer is an adhesive layer.

10. The viewer-side polarizing plate of claim 1, wherein the resin layer is formed of a composition comprising a non-birefringent resin.

11. The viewer-side polarizing plate of claim 10, wherein the non-birefringent resin comprises at least one selected from (meth)acrylate resins and polyester resins.

12. The viewer-side polarizing plate of claim 10, wherein the composition further comprises a curing agent.

13. The viewer-side polarizer of claim 1, wherein the first optical functional layer has a thickness of 100 micrometers or less.

14. The viewer-side polarizer of claim 1, wherein the first protective layer comprises a retardation film.

15. The viewer-side polarizer of claim 14, wherein the first protective layer further comprises a functional layer, the functional layer comprising at least one selected from a hard coating layer, a scattering layer, a low reflectivity layer, an ultra-low reflectivity layer, a base coating layer, a fingerprint-resistant layer, an anti-reflective layer, and an anti-glare layer.

16. The viewer-side polarizing plate according to claim 1, further comprising: A second optical functional layer is inserted between the first optical functional layer and the first protective layer.

17. The viewer-side polarizer of claim 16, wherein the second optical functional layer comprises: Resin layer; and needle-like particles.

18. The viewer-side polarizer of claim 17, wherein the longitudinal direction of the needle-like particles in the second optical functional layer forms an angle of 85° to 95° relative to the longitudinal direction of the needle-like particles in the first optical functional layer.

19. An optical display device comprising a viewer-side polarizing plate as claimed in any one of claims 1 to 18.

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