Polarization plate and optical display device including the same

Abstract

To provide a polarization plate excellent in manufacturing process performance, and further to provide a polarization plate in which both end portions of a liquid crystal retardation layer have an excellent appearance.SOLUTION: There are provided: a polarization plate that includes a polarizer and a first retardation layer stacked on one surface of the polarizer, wherein the first retardation layer is a liquid crystal retardation layer, and the first retardation layer includes first regions on opposite end portions of the first retardation layer in a width direction, and a second region between the first regions, wherein each of the first regions has a tear strength less than a tear strength of the second region; and an optical display device including the polarization plate.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a polarizing plate and an optical display device including the same. [Background technology]

[0002] Anti-reflection polarizing plates are used to suppress the decrease in visibility due to the reflection of external light. As an example, a circular polarizing plate composed of a polarizer and a retardation layer is known as an anti-reflection polarizing plate. A circular polarizing plate converts external light heading toward an image display panel into linearly polarized light by the polarizer, and then converts it into circularly polarized light by the retardation layer. The external light converted into circularly polarized light is reflected on the surface of the image display panel, and upon reflection, the direction of rotation of the polarization plane rotates in the opposite direction, and the light is converted into linearly polarized light by the retardation layer, and then blocked by the subsequent polarizer. As a result, the emission of external light to the outside is significantly suppressed, thereby providing an anti-reflection effect.

[0003] The retardation layer may be a liquid crystal retardation layer, which has the advantage of being thinner than a polymer retardation layer produced by stretching.

[0004] The background art of the present invention is disclosed in Patent Document 1 and the like. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Korean Patent Publication No. 10-2015-0113886 Summary of the Invention [Problem to be solved by the invention]

[0006] One embodiment provides a polarizing plate with excellent manufacturing process performance.

[0007] Another embodiment provides a polarizing plate having excellent appearances at both ends of a liquid crystal retardation layer.

[0008] One embodiment is a polarizing plate. [Means for solving the problem]

[0009] (1) The polarizing plate includes a polarizer and a first retardation layer laminated on one side of the polarizer, the first retardation layer being a liquid crystal retardation layer, the first retardation layer comprising first regions at both ends in the width direction of the first retardation layer and a second region between the first regions, and the first region has an even lower tear strength than the second region.

[0010] (2) In (1), the first region may be a region where liquid crystal is not aligned, and the second region may be a region where liquid crystal is aligned.

[0011] (3) In (2), the ratio of the tear strength of the first region to the tear strength of the second region [(tear strength of the first region) / (tear strength of the second region)] may be greater than 0 and less than or equal to 0.5.

[0012] (4) In (3), the first region may have a tear strength of less than 0.10 N.

[0013] (5) In (4), the second region may have a tear strength of 0.10 N or more.

[0014] (6) In (5), when the entire width of the first retardation layer is taken as 100%, the ratio of the width of the first region may be greater than 0% and less than or equal to 10%.

[0015] (7) In (6), the first region may be a region extending from 5 mm to 15 mm from one end of the first retardation layer.

[0016] (8) In (7), the first retardation layer may be a positive A plate.

[0017] (9) In (8), an alignment film may be further provided on the lower surface of the first retardation layer.

[0018] (10) In (9), the alignment film may be made up of a first portion corresponding to the first region and a second portion corresponding to the second region.

[0019] (11) In (10), the first portion may be a portion that has not been subjected to an alignment treatment, and the second portion may be a portion that has been subjected to an alignment treatment.

[0020] (12) In (11), an adhesive layer may be further laminated on one surface of the first retardation layer.

[0021] (13) In (12), the polarizing plate may further include a second retardation layer having an in-plane retardation at a wavelength of 550 nm different from that of the first retardation layer.

[0022] (14) In (13), the second retardation layer may be a positive C plate.

[0023] (15) In (14), the polarizing plate may further include a protective layer.

[0024] (16) According to another embodiment, there is provided an optical display device including a polarizing plate. Effect of the Invention

[0025] An embodiment of the present invention may provide a polarizing plate having excellent manufacturing process performance.

[0026] According to another embodiment, a polarizing plate having excellent appearances at both ends of a liquid crystal retardation layer can be provided. [Brief description of the drawings]

[0027] [Figure 1] 1 is a diagram illustrating a process for manufacturing a polarizing plate according to an embodiment of the present invention; [Diagram 2] 1 is a diagram illustrating a schematic structure of a polarizing plate according to an embodiment. [Diagram 3] 13 is a schematic diagram illustrating a structure of a polarizing plate according to another embodiment. [Figure 4]13 is a schematic view illustrating a structure of a polarizing plate according to yet another embodiment. [Diagram 5] 13 is a schematic view illustrating a structure of a polarizing plate according to yet another embodiment. [Figure 6] FIG. 2 is a plan view of a test piece for measuring tear strength. [Figure 7] FIG. 7 is a cross-sectional view of a test piece for measuring tear strength along I-II in FIG. 6. [Figure 8] 1 is a cross-sectional image of a liquid crystal retardation layer (positive A plate) and an adhesive layer in Example 1. [Figure 9] 1 is a cross-sectional image of a liquid crystal retardation layer (positive A plate) and an adhesive layer of a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, in which: FIG. 1 is a block diagram showing a method for manufacturing a semiconductor device according to the present invention;

[0029] In order to clearly explain the present invention in the drawings, parts not related to the explanation are omitted, and the same names are used for the same or similar components throughout the specification. The length and size of each component in the drawings are for the purpose of explaining the present invention, and the present invention is not limited to the length and size of each component shown in the drawings. The dotted lines in the drawings indicate that two adjacent objects are integrated with each other.

[0030] The terms used in this specification are merely used to describe exemplary embodiments and are not intended to limit the present invention. A singular expression includes a plural expression unless otherwise clearly indicated in the context.

[0031] As used herein, "combinations thereof" refers to mixtures, laminates, composites, copolymers, alloys, blends, reaction products, and the like of compositions.

[0032] In this specification, the terms "comprise", "comprise", "have" and the like are intended to specify the presence of embodied features, numbers, steps, components, or combinations thereof, but are to be understood as not precluding the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0033] In this specification, "upper" and "lower" are defined based on the drawings, and "upper" may change to "lower" and "lower" may change to "upper" depending on the viewing angle.

[0034] In this specification, for an optical element, a "front retardation (Re)" is represented by the following formula A, a "thickness direction retardation (Rth)" is represented by the following formula B, and a "degree of biaxiality (NZ)" is represented by the following formula C.

[0035] [Formula A] Re = (nx-ny) × d [Formula B] Rth = ((nx + ny) / 2-nz) × d [Formula C] NZ = (nx-nz) / (nx-ny) (In Equations A to C, nx, ny, and nz are the refractive indices in the slow axis direction, fast axis direction, and thickness direction of the optical element at the measurement wavelength, respectively, and d is the thickness of the optical element (unit: nm).)

[0036] The optical element may be a retardation layer, a protective layer, or a laminate thereof. Unless otherwise specified, the retardation, the degree of biaxiality, and the thickness direction retardation refer to values ​​measured by transmitting light in the normal direction to the in-plane direction of the optical element.

[0037] In this specification, the axis with the highest refractive index among the in-plane directions is defined as the “slow axis”, and the axis with the lowest refractive index among the in-plane directions is defined as the “fast axis”. In one embodiment, the slow axis and the fast axis may be substantially perpendicular to each other, but are not limited to this.

[0038] In this specification, when a numerical range is expressed, "X to Y" means from X to Y.

[0039] According to one embodiment, the polarizing plate includes a polarizer and a first retardation layer laminated on one side of the polarizer, the first retardation layer being a liquid crystal retardation layer, the first retardation layer having a first region at both ends in the width direction and a second region located between the first regions, and the first region having a lower tear strength than the second region.

[0040] The first region has a lower tear strength than the second region. The tear strength relationship is such that when the first retardation layer, which is a liquid crystal retardation layer, is delaminated from the substrate film and the first retardation layer is transferred during the manufacturing process of the polarizing plate, the polarizing plate manufacturing process line is not contaminated by the scattering of liquid crystal residues at both ends of the first retardation layer, thereby realizing excellent manufacturing process performance of the polarizing plate. In addition, the tear strength relationship is such that when the first retardation layer, which is a liquid crystal retardation layer, is delaminated from the substrate film during the manufacturing process of the polarizing plate, the both ends of the first retardation layer are easily delaminateable from the substrate film, thereby improving the appearance at both ends of the first retardation layer.

[0041] In the process of manufacturing a polarizing plate by laminating and bonding an adherend (a laminate of a polarizer or a polarizer, a protective layer, and an adhesive layer) and a base film on which a layer for a first retardation layer is formed, and then transferring the first retardation layer to the adherend, if the width of the adhesive layer is smaller than the width of the layer for a first retardation layer, the relationship of tear strength was taken into consideration in order to prevent contamination of the polarizing plate manufacturing process line and to provide an excellent appearance at both ends of the first retardation layer.

[0042] According to one embodiment, the first region may be a liquid crystal non-alignment region and the second region may be a liquid crystal alignment region.

[0043] In the following, the description will be limited to the case where the first region is a liquid crystal non-alignment region and the second region is a liquid crystal alignment region. Therefore, in the following description, the "liquid crystal non-alignment region" may be substantially the same as the "first region," and the "liquid crystal alignment region" may be substantially the same as the "second region." However, even if the first region and the second region are both liquid crystal alignment regions, the first region and the second region may be included in the polarizing plate according to this embodiment as long as the tear strength of the first region is lower than that of the second region.

[0044] First, the manufacturing process of the polarizing plate will be described with reference to FIG.

[0045] Referring to Figure 1, an adhesive layer 20 and a polarizer 10 (although not shown in Figure 1, a laminate of a polarizer and a protective layer can also be used instead of the polarizer 10) are laminated and bonded together to produce a laminate for producing a polarizing plate.

[0046] Next, a base film 100 having a layer 35 for a first retardation layer formed on its upper surface is provided. The width of the adhesive layer 20 is smaller than that of the layer 35 for a first retardation layer. The layer 35 for a first retardation layer has liquid crystal non-alignment regions 35a at both ends in the width direction, and a liquid crystal alignment region 32 located between the liquid crystal non-alignment regions 35a. Here, the "base film" is not particularly limited as long as it is a polymer film that is generally used for transferring a liquid crystal retardation layer. For example, the base film may be a polyester film such as polyethylene terephthalate (PET). The width of the liquid crystal alignment region 32 is smaller than that of the adhesive layer 20.

[0047] Subsequently, the adhesive layer 20 and the layer for the first retardation layer 35 of the laminate for producing a polarizing plate are laminated and bonded together.

[0048] Subsequently, the substrate film 100 is delaminate and a portion of the liquid crystal alignment region 32 and the liquid crystal non-alignment region 35a is transferred to the lower surface of the adhesive layer 20, thereby providing a polarizing plate in which the polarizer 10 or a laminate of a polarizer and a protective layer, the adhesive layer 20, and the first retardation layer 30 [consisting of the liquid crystal alignment region 32 and the liquid crystal non-alignment region 31 which is a portion of the liquid crystal non-alignment region 35a] are sequentially laminated.

[0049] By peeling off the base film 100, the remainder of the liquid crystal non-alignment region 35a remains on the upper surface of the base film 100.

[0050] The liquid crystal non-alignment region 35a has a lower tear strength than the liquid crystal alignment region 32. Therefore, when the layer 35 for the first retardation layer is peeled off from the base film 100, the liquid crystal alignment region 32 of the layer 35 for the first retardation layer is easily peeled off from the base film 100. Meanwhile, the portion 35a of the liquid crystal non-alignment region 35a that is not laminated and bonded to the adhesive layer 20 has a low tear strength, and since it is not laminated and bonded to the adhesive layer 20, it is not peeled off from the base film 100 and remains on the base film 100, so that the appearance of the first retardation layer 30 of the polarizing plate can be improved. In addition, when the base film is peeled off, the portion of the liquid crystal non-alignment region that is not laminated and bonded to the adhesive layer is not peeled off, so that the problem of contamination of the polarizing plate manufacturing process line due to scattering of liquid crystal residue can be prevented.

[0051] According to one embodiment, the adhesive layer 20 may have substantially the same width as the first retardation layer 30 .

[0052] Here, the "tear strength" is measured for a test piece consisting of only a liquid crystal retardation layer or a test piece consisting of two layers, a liquid crystal retardation layer and an alignment film, and can be measured for each of the first and second regions by the following method.

[0053] [Method of measuring tear strength] The tear strength can be measured based on KS K ISO 13937-2 (method of measuring tear strength of trouser-shaped test piece, single tear method). See Figs. 6 and 7.

[0054] The tear strength measurement test piece is a pants-shaped substrate (e.g., paper) 1 on which a liquid crystal retardation layer 3 is laminated. The substrate 1 is composed of an area 1a where the liquid crystal retardation layer 3 is laminated and bonded, and an area 1b where the liquid crystal retardation layer is not laminated and bonded. The substrate 1 has a pants-like shape with a rectangle of length (200±2 mm) and width (50±1 mm) removed from the center of the width with a rectangle of length (150±2 mm) and width (2 mm). The liquid crystal retardation layer 3 is in the form of a rectangle of length (150±2 mm) and width (50±1 mm).

[0055] The test specimen is attached to a tensile tester TA.XTplusC Texture Analyser (Stable Micro Systems), and two jigs (upper and lower jigs) of the tensile tester are engaged with the regions 1b where the liquid crystal retardation layer is not laminated and bonded, respectively. The cutting line of the test specimen is aligned so that it passes through the center line, and the regions 1b of the test specimen where the liquid crystal retardation layer is not laminated and bonded are engaged one by one from the top to the bottom at 25°C to the tear test start position (*, 4) to the tear test end position (**, 5), and the total gripping length is 100 ± 1 mm. When engaging the test specimen with the tester, care is taken not to tear the single region of the liquid crystal retardation layer, and the region 1b of the test specimen that is not cut is left freely. Care is taken so that the occurrence of the tear is parallel to the cut part, and each crotch of the test specimen is positioned in the direction of the applied force. No initial load is applied when the test begins. The device for recording the tear strength is operated. The moving clamp is moved at an extension rate of 300 mm / min, and then the specimen is torn to the point indicated at the end. After the test is completed, the average of the maximum peaks from the first peak to the last peak is calculated. The first peak area is excluded from the calculation. The peaks included in the calculation are those that have caused an increase or decrease in strength of at least 10%.

[0056] According to one embodiment, in the first retardation layer, the ratio of the tear strength of the liquid crystal non-aligned region to the tear strength of the liquid crystal aligned region [(tear strength of the liquid crystal non-aligned region) / (tear strength of the liquid crystal aligned region)] may be greater than 0 and equal to or less than 0.5, for example, 0.1 to 0.5, 0.1 to 0.4, or 0.1 to 0.3. Within this range, the appearance of the first retardation layer in the polarizing plate can be improved despite the transfer of the liquid crystal retardation layer, and the problem of contamination of the polarizing plate manufacturing process line due to scattering of liquid crystal residue can be prevented.

[0057] According to an embodiment, in the first retardation layer, the tear strength of the liquid crystal non-alignment region may be less than 0.10 N, for example, 0 N or more and less than 0.10 N, 0.01 N to 0.08 N, 0.03 N to 0.08 N, or 0.04 N to 0.08 N. Within this range, the above-mentioned effects can be provided for the polarizing plate manufacturing process and the polarizing plate manufactured therefrom.

[0058] According to one embodiment, in the first retardation layer, the tear strength of the liquid crystal alignment region may be 0.10 N or more, for example, 0.10 N to 0.50 N, 0.20 N to 0.40 N, 0.25 N to 0.30 N, or 0.25 N to 0.27 N. In this range, the bond strength between liquid crystal molecules in the liquid crystal alignment region is excellent, so that the reliability of the first retardation layer can be improved.

[0059] In FIG. 1, the width (A) of the liquid crystal non-alignment region 35a in the laminate of the layer for the first retardation layer 35 and the base film 100 is not particularly limited, but may be 15 mm to 40 mm.

[0060] Although not shown in FIG. 1, in the base film 100 on which the layer for the first retardation layer 35 is formed, an alignment film may be further formed between the base film 100 and the layer for the first retardation layer 35. The alignment film may facilitate the formation of the liquid crystal alignment region 32 and the liquid crystal non-alignment region 35a. This will be described in detail below. According to one embodiment, the width of the layer for the first retardation layer 35 may be the same as the width of the alignment film.

[0061] The first retardation layer is composed of liquid crystal non-alignment regions located at both ends in the width direction and liquid crystal alignment regions located between the liquid crystal non-alignment regions.

[0062] The liquid crystal alignment region may be a region in which liquid crystal molecules are aligned in a predetermined alignment direction and at a predetermined tilt angle. The liquid crystal alignment region may have a predetermined range of in-plane retardation at a wavelength of 550 nm depending on the alignment direction and tilt angle. According to one embodiment, the polarizer may function as an anti-reflection polarizer due to the liquid crystal alignment region.

[0063] According to one embodiment, the liquid crystal alignment region may have an in-plane retardation of 100 nm to 200 nm, for example, 100 nm to 150 nm, at a wavelength of 550 nm. According to another embodiment, the liquid crystal alignment region may have an in-plane retardation of more than 200 nm to 300 nm, for example, 210 nm to 275 nm, at a wavelength of 550 nm. According to yet another embodiment, the liquid crystal alignment region may have an in-plane retardation of less than 100 nm, for example, 0 nm to 10 nm, at a wavelength of 550 nm. Preferably, the liquid crystal alignment region may have an in-plane retardation of 100 nm to 200 nm, for example, 100 nm to 150 nm, at a wavelength of 550 nm.

[0064] According to one embodiment, the liquid crystal alignment region may have a thickness direction retardation of less than 0 nm, for example, −60 nm to −30 nm. According to another embodiment, the liquid crystal alignment region may have a thickness direction retardation of 0 nm or more, for example, 100 nm to 160 nm.

[0065] According to an embodiment, the liquid crystal alignment region may have reverse wavelength dispersion, positive wavelength dispersion, or flat wavelength dispersion as optical properties. Here, "reverse wavelength dispersion" means that the in-plane retardation increases gradually from short wavelength to long wavelength, "positive wavelength dispersion" means that the in-plane retardation decreases gradually from short wavelength to long wavelength, and "flat wavelength dispersion" means that the in-plane retardation has a substantially uniform value from short wavelength to long wavelength. Preferably, the liquid crystal alignment region may have reverse wavelength dispersion.

[0066] According to an embodiment, the liquid crystal alignment region may be a positive A plate (nx>ny=nz), a negative A plate (nx=nz>ny), a positive B plate (nz>nx>ny), a negative B plate (nx>ny>nz), a positive C plate (nz>nx=ny), or a negative C plate (nx=ny>nz). Preferably, the liquid crystal alignment region may be a positive A plate. Here, nx, ny, and nz are the refractive indices of the liquid crystal alignment region in the slow axis direction, fast axis direction, and thickness direction at a wavelength of 550 nm, respectively.

[0067] According to an embodiment, the liquid crystal alignment region may include a cured liquid crystal composition for the liquid crystal alignment region. The cured liquid crystal composition may be formed by treating the liquid crystal composition with heat curing, photo curing, or a combination thereof.

[0068] The liquid crystal composition may contain a polymerizable compound that exhibits liquid crystallinity through polymerization. The polymerizable compound may have one or more polymerizable crosslinking groups. For example, the polymerizable crosslinking group may be a photocurable crosslinking group, such as an acrylate group, a methacrylate group, a vinyl group, a vinyloxy group, an epoxy group, an oxetane group, a thiol group, a maleimide group, or a modified form thereof.

[0069] The liquid crystal composition may further include a polymerizable compound that does not exhibit liquid crystallinity by polymerization but facilitates the formation of the first retardation layer. The polymerizable compound may have one or more polymerizable crosslinking groups. For example, the polymerizable crosslinking group may be an acrylate group, a methacrylate group, a vinyl group, a vinyloxy group, an epoxy group, an oxetane group, a thiol group, a maleimide group, or a modified form thereof.

[0070] The liquid crystal composition may further include a liquid crystal compound. Although the liquid crystal compound does not have one or more polymerizable crosslinking groups, the liquid crystal compound may be included in the liquid crystal composition to facilitate the formation of a liquid crystal retardation layer.

[0071] The liquid crystal composition may further include additives that are generally included in the realization of a liquid crystal retardation layer, such as a photoinitiator, a surface modifier, an antioxidant, etc. The liquid crystal composition may further include a solvent for the ease of manufacturing a liquid crystal layer having a uniform surface.

[0072] Even if the liquid crystal non-alignment region has the above-mentioned liquid crystal alignment region, it can improve the appearance of both ends of the first retardation layer of the polarizing plate, and when peeling off the substrate film in the polarizing plate manufacturing process, it can prevent the problem of contamination of the polarizing plate manufacturing line due to scattering of liquid crystal residue caused by peeling off of the part that is not laminated with the adhesive layer in the liquid crystal non-alignment region.

[0073] The liquid crystal non-alignment region can be a region in which liquid crystal molecules are not aligned in a predetermined alignment direction and at a predetermined tilt angle. Therefore, the liquid crystal non-alignment region does not contribute to the first retardation layer exhibiting the above-mentioned in-plane retardation, wavelength dispersion, and optical characteristics. Instead, the liquid crystal non-alignment region can improve the appearance of both ends of the first retardation layer of the polarizing plate, and can prevent the problem of contamination of the polarizing plate manufacturing line due to scattering of liquid crystal residues caused by peeling off the part of the liquid crystal non-alignment region that is not laminated with the adhesive layer when the base film is peeled off during the polarizing plate manufacturing process.

[0074] The liquid crystal non-alignment region may include a cured product of a liquid crystal composition for the liquid crystal non-alignment region. The cured product of the liquid crystal composition may be formed by treating the liquid crystal composition with heat curing, photocuring, or a combination thereof.

[0075] The liquid crystal composition may contain a polymerizable compound that exhibits liquid crystallinity through polymerization. The polymerizable compound may have one or more polymerizable crosslinking groups. For example, the polymerizable crosslinking group may be a photocurable crosslinking group, such as an acrylate group, a methacrylate group, a vinyl group, a vinyloxy group, an epoxy group, an oxetane group, a thiol group, a maleimide group, or a modified form thereof.

[0076] The liquid crystal composition may further include a polymerizable compound that does not exhibit liquid crystallinity by polymerization but facilitates the formation of the first retardation layer. The polymerizable compound may have one or more polymerizable crosslinking groups. For example, the polymerizable crosslinking group may be an acrylate group, a methacrylate group, a vinyl group, a vinyloxy group, an epoxy group, an oxetane group, a thiol group, a maleimide group, or a modified form thereof.

[0077] The liquid crystal composition may further include a liquid crystal compound. Although the liquid crystal compound does not have one or more polymerizable crosslinking groups, the liquid crystal compound may be included in the liquid crystal composition to facilitate the formation of a liquid crystal retardation layer.

[0078] The liquid crystal composition may further include additives that are generally included in the realization of a liquid crystal retardation layer, such as a photoinitiator, a surface modifier, an antioxidant, etc. The liquid crystal composition may further include a solvent for the ease of manufacturing a liquid crystal layer having a uniform surface.

[0079] When the entire width of the first retardation layer is taken as 100%, the ratio of the width of the liquid crystal non-alignment regions formed on both ends of the first retardation layer (the ratio of the width (B) of one liquid crystal non-alignment region 31 to the entire width (C) of the first retardation layer 30 in FIG. 2 = B / C) may be greater than 0% and less than 10%, for example, 1% to 10%, or 2% to 8%. Within this range, the above-mentioned effects can be realized without affecting the optical functions including the anti-reflection function of the liquid crystal alignment regions in the polarizing plate.

[0080] According to one embodiment, the liquid crystal non-alignment region may be a region (B in FIG. 2) that is 5 mm to 15 mm, for example 10 mm to 15 mm, from one end of the first retardation layer. In this range, the above-mentioned effects can be realized.

[0081] According to one embodiment, the liquid crystal non-alignment region may be integrated with the liquid crystal alignment region. Here, "integration" means that the interface between the liquid crystal non-alignment region and the liquid crystal alignment region is not completely separated and is not flat. According to one embodiment, the liquid crystal composition for the liquid crystal non-alignment region and the liquid crystal alignment region are the same, so the first retardation layer may be manufactured by simultaneously forming the liquid crystal non-alignment region and the liquid crystal alignment region by one coating of the liquid crystal composition for the liquid crystal non-alignment region (or the liquid crystal composition for the liquid crystal alignment region).

[0082] The thickness of the first retardation layer may be greater than 0 μm and equal to or less than 10 μm, for example, 0.1 μm to 10 μm, or 0.5 μm to 5 μm. Within this range, a desired retardation can be realized.

[0083] The manufacturing method of the first retardation layer is not limited as long as it can realize a liquid crystal non-aligned region and a liquid crystal aligned region. However, in order to facilitate the formation of the first retardation layer, the first retardation layer may further include an alignment film on the lower surface of the first retardation layer, i.e., the surface facing the polarizer.

[0084] The alignment layer serves to align the liquid crystal compound in a desired direction and also serves to adjust the tear strength of each of the non-aligned liquid crystal region and the aligned liquid crystal region.

[0085] The alignment film may be composed of a first portion and a second portion. The first portion corresponds to a liquid crystal non-aligned region in the first retardation layer. The second portion may be located between the first portions and corresponds to a liquid crystal aligned region in the first retardation layer.

[0086] The second part is an alignment film that has been subjected to an alignment treatment and may include a cured product of a coating film formed from a composition for forming an alignment film, which may facilitate the formation of a liquid crystal alignment region when a liquid crystal composition is coated on the second part and cured.

[0087] Meanwhile, the first portion is an alignment film that has not been subjected to an alignment treatment, and may include a coating film formed from a composition for forming an alignment film, but may also include a non-cured material that has not been cured. This makes it easy to form a liquid crystal non-alignment region by allowing the liquid crystal to be cured in a non-aligned state even if the liquid crystal composition is coated on the first portion and cured.

[0088] According to one embodiment, the first and second portions of the alignment film may be integrated, where "integrated" means that the interface between the first and second portions is not completely distinct and is not flat.

[0089] According to an embodiment, the alignment film may have a first portion and a second portion formed by one coating of an alignment film-forming composition.

[0090] According to one embodiment, the alignment film may be a rubbed film made of an organic compound such as a polymer, an obliquely evaporated film of an inorganic compound, a film having microgrooves, or a film obtained by stacking LB films made of an organic compound such as tricosanoic acid, dioctadecylmethylammonium chloride, or methyl stearyl acid. Alternatively, the alignment film may be an alignment film that can perform alignment function by irradiation with light. The composition for forming the alignment film may include polyimide, polyvinyl alcohol, modified polyvinyl alcohol, or a polymer having a polymerizable group. The alignment treatment may be performed by rubbing the surface of the polymer layer, irradiating a photo-alignable material with polarized or non-polarized light, or heating a coating of the composition for forming the alignment film.

[0091] According to one embodiment, the alignment film can be formed by adjusting the presence or absence of alignment treatment in the first and second parts and / or the alignment angle in the first and second parts when the coating film formed by coating the composition for forming the alignment film is aligned, thereby forming the second part and the first part. This can provide a relationship in tear strength between the liquid crystal alignment region and the liquid crystal non-alignment region in the first retardation layer.

[0092] According to another embodiment, the alignment film is formed by coating the composition for forming an alignment film and heat-treating (thermosetting) only a part of the coating film formed, and the remaining part is not heat-treated (thermosetting) to form the first part. Through this, it may be easy to obtain a relationship in tear strength between the liquid crystal alignment region and the liquid crystal non-alignment region from the first retardation layer.

[0093] According to yet another embodiment, the relationship in tear strength between the liquid crystal alignment region and the liquid crystal non-alignment region from the first retardation layer may be achieved by adjusting the type of liquid crystal composition and / or the degree of photocuring of the liquid crystal composition.

[0094] The thickness of the alignment film may be greater than 0 μm and equal to or less than 1 μm, for example, 10 nm to 800 nm, or 100 nm to 600 nm. Within this range, a desired retardation can be realized.

[0095] Polarizer A polarizer converts incident natural light or polarized light into linearly polarized light in a specific direction, and may be manufactured from a polymer film mainly composed of a polyvinyl alcohol-based resin. Specifically, the polarizer may be manufactured by dyeing a polymer film with iodine or a dichroic dye and stretching it in the MD (machine direction), or by forming a polyene bond through a dehydration reaction using an acid catalyst, etc. In one embodiment, the polarizer may be manufactured by subjecting a polyvinyl alcohol-based film to a swelling process, a dyeing step, a stretching step, or selectively one or more of a complementary color step and a crosslinking step.

[0096] The polarizer has a light absorption axis and a light transmission axis in the in-plane directions, and the light absorption axis may be in the MD of the polarizer, and the light transmission axis may be in the TD (transverse direction) of the polarizer.

[0097] The polarizer may have a total light transmittance of 40% or more, for example, 40% to 47%, and a polarization degree of 95% or more, for example, 95% to 99.9999%. When combined with a retardation layer in this range, the anti-reflection performance can be improved. The "light transmittance" and "polarization degree" are values ​​measured at wavelengths of 380 nm to 780 nm, and are values ​​that reflect the visual sensitivity in the corresponding wavelength range, and may be measured by a conventional method known to those skilled in the art.

[0098] The polarizer may have a thickness of 2 μm to 30 μm, specifically 4 μm to 25 μm, and may be used in a polarizing plate within this range.

[0099] The polarizing plate may further include an adhesive layer on the upper surface of the first retardation layer, i.e., on the polarizer side.

[0100] adhesive layer The adhesive layer is laminated on one side of the first retardation layer and serves to adhere the first retardation layer to an adherend. Here, the "adherend" may include a polarizer, a protective layer described below, or another retardation layer described below.

[0101] According to one embodiment, the adhesive layer may be laminated and bonded to both the liquid crystal alignment region and the liquid crystal non-alignment region of the first liquid crystal retardation layer. In particular, the adhesive layer may be laminated and bonded to the liquid crystal non-alignment region as well, so that the appearance of both ends of the first retardation layer through the liquid crystal non-alignment region can be improved as shown in FIG.

[0102] According to an embodiment, in the peel strength of the adhesive layer in Fig. 1, the peel strength between the layer for the first retardation layer or the layer for the first retardation layer and the alignment film and the adhesive layer may be higher than the peel strength between the layer for the first retardation layer or the layer for the first retardation layer and the alignment film and the substrate film. This can prevent contamination of the polarizing plate manufacturing process line due to scattering of liquid crystal residue at both ends of the first retardation layer when the substrate film is peeled off as in Fig. 1, and can improve the appearance at both ends of the first retardation layer.

[0103] According to one embodiment, the adhesive layer may be a pressure sensitive adhesive layer. This not only has a high peel strength between the first retardation layer and the adherend, but also has good removability, improving process performance. According to one embodiment, the adhesive layer may include, but is not limited to, (meth)acrylic, epoxy, silicone, urethane, or urethane (meth)acrylic adhesive resins.

[0104] According to one embodiment, the adhesive layer may have a thickness of 2 μm to 30 μm, specifically 4 μm to 25 μm, and can be used for the polarizing plate within this range.

[0105] The polarizing plate may further include a protective layer on one or more of the upper surface of the polarizer or the lower surface of the polarizer, for example, between the polarizer and the first retardation layer, or on the lower surface of the first retardation layer. The polarizing plate may include one or more protective layers.

[0106] protective layer The protective layer can provide additional functions to the retardation layer and / or the polarizing plate. For example, the protective layer can enhance the durability and mechanical strength of the polarizing plate by complementing the thickness of the polarizing plate. Alternatively, the protective layer can prevent iodine, which may be dissolved from the polarizer after the polarizing plate is left at high temperature and high humidity for a long period of time, from contaminating the retardation layer and / or the panel.

[0107] The protective layer is an optically transparent film, and may be a film made of one or more resins selected from the group consisting of cellulose-based resins including triacetyl cellulose (TAC) and the like, polyester-based resins including polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate (PET), polybutylene naphthalate, and the like, cyclic polyolefin-based resins, polycarbonate-based resins, polyethersulfone-based resins, polysulfone-based resins, polyamide-based resins, polyimide-based resins, polyolefin-based resins, polyarylate-based resins, polyvinyl alcohol-based resins, polyvinyl chloride-based resins, and polyvinylidene chloride-based resins.

[0108] According to one embodiment, the protective layer may have a front retardation of 10 nm or less at a wavelength of 550 nm, for example, 0 nm to 5 nm. In this range, the effect of using the protective layer can be obtained without affecting the reflectance reduction effect at the front and side surfaces by the liquid crystal retardation layer.

[0109] The protective layer may have a thickness of 5 μm to 100 μm, specifically 15 μm to 45 μm, and a thickness within this range can be used for the polarizing plate.

[0110] The polarizing plate may further include a second retardation layer on one or more of the upper surface of the polarizer or the lower surface of the polarizer, for example, between the polarizer and the first retardation layer, or on the lower surface of the first retardation layer. The second retardation layer may mean a layer having a different retardation value at a wavelength of 550 nm or other optical properties compared to the liquid crystal alignment region of the first retardation layer. The polarizing plate may include one or more second retardation layers.

[0111] Second retardation layer According to one embodiment, the second retardation layer may have an in-plane retardation of less than 100 nm, for example, 0 nm to 10 nm, at a wavelength of 550 nm. According to another embodiment, the second retardation layer may have an in-plane retardation of 100 nm to 200 nm, for example, 100 nm to 150 nm, at a wavelength of 550 nm. According to yet another embodiment, the second retardation layer may have an in-plane retardation of more than 200 nm to 300 nm or less, for example, 210 nm to 275 nm, at a wavelength of 550 nm.

[0112] According to one embodiment, the second retardation layer may have a thickness direction retardation of less than 0 nm, for example, −60 nm to −30 nm. According to another embodiment, the second retardation layer may have a thickness direction retardation of 0 nm or more, for example, 100 nm to 160 nm.

[0113] According to an embodiment, the second retardation layer may have a wavelength dispersion characteristic that is reverse, normal, or flat.

[0114] According to an embodiment, the second retardation layer may have the optical properties of a positive A plate, a negative A plate, a positive B plate, a negative B plate, a positive C plate, or a negative C plate. Preferably, the second retardation layer may be a positive C plate.

[0115] According to an embodiment, the second retardation layer may be a liquid crystal layer or a non-liquid crystal layer. The liquid crystal layer is a layer formed of a liquid crystal composition and may be manufactured from a conventional liquid crystal known to those skilled in the art. The non-liquid crystal layer may be a stretched film manufactured by stretching an unstretched film manufactured by melt extrusion or solvent casting of a polymer-containing composition, or a coating layer manufactured by coating the polymer-containing composition.

[0116] According to one embodiment, the second retardation layer may have a thickness of less than 3.5 μm, for example, 0.5 μm to 3.4 μm, in which range a desired retardation can be achieved.

[0117] 2 is a cross-sectional view of a polarizing plate according to an embodiment. Referring to FIG. 2, the polarizing plate includes a polarizer 10, an adhesive layer 20 sequentially laminated on the lower surface of the polarizer 10, and a first retardation layer 30. The first retardation layer 30 includes liquid crystal non-alignment regions 31 located at both ends in the width direction, and liquid crystal alignment regions 32 located between the liquid crystal non-alignment regions 31.

[0118] 3 is a cross-sectional view of a polarizing plate according to another embodiment. Referring to FIG. 3, the polarizing plate includes a polarizer 10, an adhesive layer 20, a first retardation layer 30, and an alignment film 40, which are sequentially laminated on the lower surface of the polarizer 10. The first retardation layer 30 includes liquid crystal non-alignment regions 31 located at both ends in the width direction, and liquid crystal alignment regions 32 located between the liquid crystal non-alignment regions 31. The alignment film 40 includes a first portion 41 corresponding to the liquid crystal non-alignment regions 31, and a second portion 42 corresponding to the liquid crystal alignment regions 32.

[0119] Fig. 4 is a cross-sectional view of a polarizing plate according to another embodiment. Referring to Fig. 4, the polarizing plate includes a polarizer 10, an adhesive layer 20, a first retardation layer 30, an alignment film 40, and a second retardation layer 50, which are sequentially laminated on the lower surface of the polarizer 10. The first retardation layer 30 includes liquid crystal non-alignment regions 31 located at both ends in the width direction, and liquid crystal alignment regions 32 located between the liquid crystal non-alignment regions 31. The alignment film 40 includes a first portion 41 corresponding to the liquid crystal non-alignment regions 31, and a second portion 42 corresponding to the liquid crystal alignment regions 32.

[0120] 5 is a cross-sectional view of a polarizing plate according to another embodiment. Referring to FIG. 5, the polarizing plate includes a polarizer 10, a protective layer 60 laminated on the upper surface of the polarizer 10, an adhesive layer 20 sequentially laminated on the lower surface of the polarizer 10, a first retardation layer 30, an alignment film 40, and a second retardation layer 50. The first retardation layer 30 includes liquid crystal non-alignment regions 31 located at both ends in the width direction, and liquid crystal alignment regions 32 located between the liquid crystal non-alignment regions 31. The alignment film 40 includes a first portion 41 corresponding to the liquid crystal non-alignment region 31, and a second portion 42 corresponding to the liquid crystal alignment region 32.

[0121] The optical display device of the present invention includes a polarizing plate according to an embodiment of the present invention. The optical display device may include an organic light emitting diode (OLED) display device and a liquid crystal display device.

[0122] In one embodiment, the organic light emitting diode display device may include an organic light emitting diode panel including a flexible substrate, and a polarizer of the present invention laminated on the organic light emitting diode panel. In another embodiment, the organic light emitting diode display device may include an organic light emitting diode panel including a non-flexible substrate, and a polarizer of the present invention laminated on the organic light emitting diode panel. EXAMPLES

[0123] The present invention will be described in more detail with reference to the preferred embodiments thereof below, however, these are presented as preferred examples of the present invention and should not be construed as limiting the present invention in any way.

[0124] Example 1 A polyvinyl alcohol film (TS#20, Kuraray Co., Ltd., thickness: 20 μm) was stretched 6 times in an iodine aqueous solution at 55° C. to produce a polarizer with a total light transmittance of 45%.

[0125] A polyethylene terephthalate (PET) film was prepared as a base film, and a composition for forming an alignment film (containing a phenol-modified resin and a phenol-containing acrylate monomer, Dai Nippon Printing Co., Ltd.) was applied to the upper surface of the PET film at a predetermined thickness to form a coating film. Using a mask, only the remaining part of the coating film, excluding the ends on both sides, was subjected to an alignment treatment at a predetermined orientation angle, and then the coating film was thermally cured to form an alignment film.

[0126] A liquid crystal retardation layer-forming composition (containing a photocurable melamine resin, Dai Nippon Printing Co., Ltd.) was applied to the entire surface of the alignment film to a predetermined thickness and photocured to form a liquid crystal retardation layer, thereby producing a laminate in which the base film-alignment film-liquid crystal retardation layer were laminated in that order.

[0127] An acrylic adhesive composition (PSA) was applied to the bottom surface of the polarizer and cured to form an adhesive layer. The prepared adhesive layer and the liquid crystal retardation layer of the laminate were laminated and bonded together. At this time, the width of the adhesive layer was smaller than the width of the liquid crystal retardation layer. After lamination and bonding, the base film was peeled off to prepare a polarizing plate laminated in the order of polarizer-adhesive layer-liquid crystal retardation layer-alignment film. The liquid crystal retardation layer was a positive A plate, and the in-plane retardation was 125 nm at a wavelength of 550 nm.

[0128] A liquid crystal retardation layer (positive C plate) was laminated on the lower surface of the alignment film to produce a polarizing plate laminated in the order of polarizer-adhesive layer-liquid crystal retardation layer (positive A plate)-alignment film-liquid crystal retardation layer (positive C plate).

[0129] Examples 2 to 4 A polarizing plate was manufactured in the same manner as in Example 1, except that the type of the composition for forming the liquid crystal retardation layer and / or the degree of photocuring were changed.

[0130] Comparative Example 1 A polarizing plate was manufactured in the same manner as in Example 1, except that a mask was not used, and the entire coating film was subjected to an alignment treatment at a predetermined alignment angle and then thermally cured to manufacture an alignment film.

[0131] The polarizing plates of the examples and comparative examples were evaluated for the following physical properties, and the evaluation results are shown in the following Table 1, and in FIGS.

[0132] Tear strength (unit: N): In the examples and comparative examples, the tear strength was measured for the laminate of the liquid crystal retardation layer (positive A plate) and the alignment film before laminating and bonding to the adhesive layer. The tear strength was measured in the same manner for the liquid crystal alignment region and the liquid crystal non-alignment region. The tear strength was measured according to the above-mentioned method based on KS K ISO 13937-2, Figures 6 and 7.

[0133] Appearance of both ends of the liquid crystal retardation layer (positive A plate): The cross sections of both ends of the liquid crystal retardation layer (positive A plate) of the manufactured polarizing plate were evaluated by the naked eye to see if they were smooth and uniform. If the cross sections of both ends of the positive A plate were smooth and uniform, it was evaluated as good, and if not, it was evaluated as bad.

[0134] Whether or not residues of the liquid crystal retardation layer (positive A plate) remain on the substrate film: In the process of manufacturing the polarizing plate in the examples and comparative examples, after peeling off the substrate film, whether or not residues of the liquid crystal retardation layer remain on the substrate film and whether or not residues have scattered were evaluated. If residues of the liquid crystal retardation layer remain on the substrate film or if residues have scattered, it was evaluated as poor, otherwise it was evaluated as good.

[0135] [Table 1]

[0136] As shown in Table 1, the appearance of both ends of the liquid crystal retardation layer was excellent, and there was no residue of the liquid crystal retardation layer (positive A plate) of the base film, and there was no scattering, so the manufacturing process performance of the polarizing plate was excellent. On the other hand, the polarizing plate of Comparative Example 1 had poor appearance of both ends of the liquid crystal retardation layer and a lot of residue, so the effect of the examples was not obtained.

[0137] As shown in Fig. 8, the cross sections of the liquid crystal retardation layer and the adhesive layer in Example 1 were smooth and uniform. However, as shown in Fig. 9, the cross sections of the liquid crystal retardation layer and the adhesive layer in Comparative Example were not uniform.

[0138] Simple modifications or alterations of the present invention may be easily implemented by a person having ordinary skill in the art, and all such modifications and alterations may be considered to be within the scope of the present invention.

Claims

1. A polarizer and a first retardation layer laminated on one surface of the polarizer, the first retardation layer is a liquid crystal retardation layer, The first retardation layer includes first regions at both ends in a width direction of the first retardation layer and a second region between the first regions, The first region has a lower tear strength than the second region.

2. The polarizing plate according to claim 1 , wherein the first region is a region where liquid crystal is not aligned, and the second region is a region where liquid crystal is aligned.

3. 2. The polarizing plate according to claim 1, wherein the ratio of the tear strength of the first region to the tear strength of the second region [(tear strength of the first region) / (tear strength of the second region)] is greater than 0 and less than or equal to 0.

5.

4. The polarizing plate according to claim 1 , wherein the tear strength of the first region is less than 0.10 N.

5. The polarizing plate according to claim 1 , wherein the tear strength of the second region is 0.10 N or more.

6. The polarizing plate according to claim 1 , wherein a ratio of a width of the first region to an overall width of the first retardation layer is greater than 0% and is not more than 10%.

7. 2. The polarizing plate according to claim 1, wherein the first region is a region that is 5 mm to 15 mm from one end of the first retardation layer.

8. The polarizing plate according to claim 1 , wherein the first retardation layer is a positive A plate.

9. The polarizing plate of claim 1 , further comprising an alignment film on a lower surface of the first retardation layer.

10. The polarizing plate according to claim 9 , wherein the alignment film comprises a first portion corresponding to the first region and a second portion corresponding to the second region.

11. The polarizer of claim 10 , wherein the first portion is a non-aligned region and the second portion is an aligned region.

12. The polarizing plate according to claim 1 , further comprising an adhesive layer laminated on one surface of the first retardation layer.

13. The polarizing plate according to claim 1 , further comprising a second retardation layer having an in-plane retardation at a wavelength of 550 nm different from that of the first retardation layer.

14. The polarizing plate according to claim 13 , wherein the second retardation layer is a positive C plate.

15. The polarizer of claim 1 , further comprising a protective layer.

16. An optical display device comprising the polarizing plate according to any one of claims 1 to 15.

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