Polarizing plate and optical display device

Abstract

Disclosed are a polarizing plate and an optical display device including the same. The polarizing plate includes: a polarizer; and a first retardation layer laminated on a surface of the polarizer, the first retardation layer being a liquid crystal retardation layer, and the first retardation layer including a plurality of first regions located on opposite end portions of the first retardation layer in a width direction and a second region located between the plurality of first regions, and each of the plurality of first regions has a tear strength that is less than a tear strength of the second region.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0073237 filed in the Korean Intellectual Property Office on June 8, 2023, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] Various aspects of embodiments of the present invention relate to a polarizing plate and an optical display device including the polarizing plate. Background Art

[0004] An antireflective polarizing plate has been used to suppress the visibility drop caused by the reflection of external light. In an example, a circular polarizing plate composed of a polarizer and a delay layer is called an antireflective polarizing plate. In a circular polarizing plate, the polarizer converts the external light directed to the image display panel into linearly polarized light, and the delay layer converts the linearly polarized light into circularly polarized light. The external light converted into circularly polarized light is reflected from the surface of the image display panel, and in this reflection, the rotation direction of the polarization plane of the circularly polarized light is reversed, and therefore, the circularly polarized light is converted into linearly polarized light by the delay layer and then blocked by the polarizer behind. Therefore, the emission of external light to the outside can be significantly suppressed, thereby providing an antireflection effect.

[0005] A liquid crystal retardation layer may be used as the retardation layer. The liquid crystal retardation layer has an advantage of providing a thin thickness compared to a polymer retardation layer manufactured by stretching.

[0006] The background art of the present invention is disclosed in Korean Patent Publication No. 10-2015-0113886 and the like. Summary of the invention

[0007] According to an aspect of an embodiment of the present invention, a polarizing plate having excellent manufacturing processability is provided.

[0008] According to another aspect of an embodiment of the present invention, there is provided a polarizing plate in which both end portions or opposite end portions of a liquid crystal retardation layer have excellent appearance.

[0009] One aspect of one or more embodiments of the present invention relates to a polarizing plate.

[0010] According to one or more embodiments, a polarizing plate includes: a polarizer; and a first delay layer stacked on the surface of the polarizer, wherein the first delay layer is a liquid crystal delay layer, and the first delay layer includes a plurality of first regions and a second region, the plurality of first regions are located on opposite end portions of the first delay layer in a width direction, and the second region is located between the plurality of first regions, wherein each of the plurality of first regions has a tear strength smaller than the tear strength of the second region.

[0011] In one or more embodiments, the plurality of first regions may be a plurality of liquid crystal non-alignment regions, and the second region may be a liquid crystal alignment region.

[0012] In one or more embodiments, the ratio of the tear strength of each of the plurality of first zones to the tear strength of the second zone [(tear strength of each of the plurality of first zones) / (tear strength of the second zone)] may be greater than 0 and less than or equal to 0.5.

[0013] In one or more embodiments, the tear strength of each of the plurality of first regions may be less than 0.10N.

[0014] In one or more embodiments, the tear strength of the second zone may be 0.10N or greater.

[0015] In one or more embodiments, if the total width of the first retardation layer is 100%, a ratio of the width of each of the plurality of first regions to the total width of the first retardation layer may be greater than 0% and less than or equal to 10%.

[0016] In one or more embodiments, each of the plurality of first regions may be a region having a width of 5 mm to 15 mm from an end portion of the first retardation layer.

[0017] In one or more embodiments, the first retardation layer may be a positive A-plate.

[0018] In one or more embodiments, the polarizing plate may further include an alignment film on a lower surface of the first retardation layer.

[0019] In one or more embodiments, the alignment film may include a plurality of first portions corresponding to the plurality of first regions and a second portion corresponding to the second region.

[0020] In one or more embodiments, the plurality of first portions may be a plurality of portions that have not been subjected to an orientation treatment, and the second portion may be a portion that has been subjected to an orientation treatment.

[0021] In one or more embodiments, the polarizing plate may further include an adhesive layer laminated on a surface of the first retardation layer.

[0022] In one or more embodiments, the polarizing plate may further include a second retardation layer having an in-plane retardation different from that of the first retardation layer at a wavelength of 550 nm.

[0023] In one or more embodiments, the second retardation layer may be a positive C-plate.

[0024] In one or more embodiments, the polarizing plate may further include a protective layer.

[0025] According to one or more embodiments, an optical display device includes the polarizing plate described above.

[0026] According to one or more embodiments, a polarizing plate having excellent manufacturing processability is provided.

[0027] According to one or more embodiments, there is provided a polarizing plate in which both end portions or opposite end portions of a liquid crystal retardation layer have excellent appearance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a view schematically illustrating a process of manufacturing a polarizing plate according to an embodiment.

[0029] Figure 2 is a view schematically showing a structure of a polarizing plate according to an embodiment.

[0030] Figure 3 is a view schematically showing a structure of a polarizing plate according to another embodiment.

[0031] Figure 4 is a view schematically showing a structure of a polarizing plate according to another embodiment.

[0032] Figure 5 is a view schematically showing a structure of a polarizing plate according to another embodiment.

[0033] Figure 6 This is a plan view of a sample used for measuring tear strength.

[0034] Figure 7 It is along Figure 6 A cross-sectional view of a sample taken along line I-II for measuring tear strength is shown.

[0035] Figure 8 is a cross-sectional image of a liquid crystal retardation layer (positive A plate) and an adhesive layer according to an example of the embodiment.

[0036] Fig. 9 It is a cross-sectional image of the liquid crystal retardation layer (positive A plate) and the adhesive layer of the comparative example. DETAILED DESCRIPTION

[0037] Some embodiments of the present invention will be described in more detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. It should be understood that the present invention can be implemented in different ways and is not limited to the embodiments described herein.

[0038] In the drawings, in order to clearly illustrate the present invention, parts not related to the description may be omitted, and the same components will be represented by the same reference numerals throughout the specification. In the drawings, the length and size of each component are provided to illustrate the present invention; however, the present invention is not limited to the length and size of each component shown in the drawings. In the drawings, dotted lines indicate that two adjacent objects are integrated with each other.

[0039] The terms used in this specification are used to describe exemplary embodiments and are not intended to limit the present invention. Unless the context clearly indicates otherwise, a singular expression includes a plural expression.

[0040] As used herein, "a combination thereof" refers to a mixture, a laminate, a composite, a copolymer, an alloy, a blend, a reaction product, etc. of a plurality of components.

[0041] It should be understood that when the terms “comprises / comprising,” “includes / including,” “contains,” and “has and / or having” are used herein, they are used to specify the presence of stated features, numerals, operations, components, or a combination thereof, but do not exclude the presence or addition of one or more other numerals, operations, components, or a combination thereof.

[0042] In the present specification, the terms “above” and “below” are defined based on the drawings, and “above” may be changed to “below” and “below” may be changed to “above” depending on the viewing angle.

[0043] In this specification, for an optical device, “front surface retardation (Re)” is represented by the following equation A, “thickness direction retardation (Rth)” is represented by the following equation B, and “biaxiality (NZ)” is represented by the following equation C.

[0044] Formula A

[0045] Re = (nx – ny)xd;

[0046] Formula B

[0047] Rth = ((nx + ny) / 2 – nz) xd;

[0048] Formula C

[0049] NZ=(nx–nz) / (nx–ny),

[0050] Wherein, in equations A to C, nx, ny and nz are the refractive indices of the optical device in the slow axis direction, the fast axis direction and the thickness direction at the measurement wavelength, respectively, and d is the thickness of the optical device (unit: nm).

[0051] The optical device may be a retardation layer, a protective layer or a laminate thereof. Unless otherwise specified, retardation, biaxiality and thickness direction retardation refer to values ​​measured by transmitting light in a normal direction relative to the in-plane direction of the optical device.

[0052] In this specification, the axis with the highest refractive index in the in-plane direction is defined as the “slow axis”, and the axis with the lowest refractive index in the in-plane direction is defined as the “fast axis.” In one or more embodiments, the slow axis and the fast axis may be substantially orthogonal to each other, but the present invention is not limited thereto.

[0053] In the present specification, when expressing a numerical range, the expression "X to Y" means greater than or equal to X and less than or equal to Y (X≤and≤Y).

[0054] According to one or more embodiments, a polarizing plate includes: a polarizer; and a first delay layer stacked on the surface of the polarizer, wherein the first delay layer is a liquid crystal delay layer, the first delay layer has a plurality of first regions and a second region, the plurality of first regions are located at two end portions or opposite end portions in a width direction, the second region is located between the plurality of first regions, and the first region has a smaller tear strength than the second region.

[0055] The tear strength relationship indicates that the tear strength of the first zone is less than the tear strength of the second zone. When the first delay layer as a liquid crystal delay layer is delaminated from the base film and the first delay layer is transferred during the manufacturing process of the polarizing plate, the tear strength relationship can enable the polarizing plate to have excellent manufacturing processability by preventing or substantially preventing liquid crystal residues from scattering from both end portions of the first delay layer and preventing contamination in the manufacturing process line of the polarizing plate. In addition, when the first delay layer as a liquid crystal delay layer is delaminated from the base film during the manufacturing process of the polarizing plate, the tear strength relationship can improve the appearance of both end portions of the first delay layer by enabling both end portions of the first delay layer to be easily delaminated from the base film.

[0056] The reason for considering the tear strength relationship is that when the width of the adhesive layer is smaller than the width of the layer for the first delay layer in the polarizing plate manufacturing process in which the adherend (a laminate of an adhesive layer and a polarizer or a laminate of an adhesive layer, a polarizer and a protective layer) and a base film (on which a layer for the first delay layer is formed) are laminated and then the first delay layer is transferred to the adherend, contamination of the polarizing plate manufacturing process line can be prevented or substantially prevented, and the appearance of the two end portions of the first delay layer can be improved.

[0057] According to an embodiment, the first region may be a liquid crystal non-alignment region and the second region may be a liquid crystal alignment region.

[0058] Herein, description will be provided with respect to a case where the first region is a liquid crystal non-aligned region and the second region is a liquid crystal aligned region. Therefore, in the following description, the "liquid crystal non-aligned region" may be substantially the same as the "first region", and the "liquid crystal aligned region" may be substantially the same as the "second region". However, if both the first region and the second region are liquid crystal aligned regions, the first region and the second region may be included in the polarizing plate according to an embodiment of the present disclosure when the tear strength of the first region is less than the tear strength of the second region.

[0059] First, refer to Figure 1 To explain the manufacturing process of polarizing plate.

[0060] Reference Figure 1 , by bonding the adhesive layer 20 to the polarizer 10 (although Figure 1 Although not shown in the figure, a laminate of a polarizer and a protective layer may be used instead of the polarizer 10 to manufacture a laminate for manufacturing a polarizing plate.

[0061] Subsequently, a base film 100 is provided, and a layer 35 for a first delay layer is formed on its upper surface. The width of the adhesive layer 20 is smaller than the width of the layer 35 for the first delay layer. The layer 35 for the first delay layer includes a liquid crystal non-oriented area 35a and a liquid crystal orientation area 32, and the liquid crystal non-oriented area 35a is at two or opposite end portions in the width direction, and the liquid crystal orientation area 32 is located between the liquid crystal non-oriented areas 35a. Here, the "base film" is not particularly limited and can be a polymer film commonly used for transferring the liquid crystal delay layer. For example, the base film can be a polyester-based film, such as a polyethylene terephthalate (PET) film. The width of the liquid crystal orientation area 32 is smaller than the width of the adhesive layer 20.

[0062] Subsequently, the adhesive layer 20 in the laminate for producing the polarizing plate and the layer 35 for the first retardation layer are laminated together.

[0063] Subsequently, the base film 100 is layered and the liquid crystal orientation zone 32 and some of the liquid crystal non-oriented zones 35a are transferred to the lower surface of the adhesive layer 20, thereby providing a polarizing plate in which a polarizer 10 or a laminate of a polarizer and a protective layer, an adhesive layer 20 and a first delay layer 30 (including the liquid crystal orientation zone 32 and the liquid crystal non-oriented zone 31, which include some of the liquid crystal non-oriented zones 35a) are sequentially stacked.

[0064] By delaminating the base film 100 , a residue of the liquid crystal non-alignment area 35 a is left on the upper surface of the base film 100 .

[0065] The liquid crystal non-orientation area 35a has a smaller tear strength than the liquid crystal orientation area 32. Therefore, when the layer 35 for the first retardation layer is delaminated from the base film 100, the liquid crystal orientation area 32 of the layer 35 for the first retardation layer is easily delaminated from the base film 100. On the other hand, the portion 35a of the liquid crystal non-orientation area 35a that is not laminated with the adhesive layer 20 is not delaminated from the base film 100 and remains on the base film 100 due to its low tear strength and is not laminated with the adhesive layer 20, thereby improving the appearance of the first retardation layer 30 of the polarizing plate. In addition, since the portion of the liquid crystal non-orientation area that is not laminated with the adhesive layer is not delaminated when the base film is delaminated, the problem of contamination of the polarizing plate manufacturing process line due to the spread of liquid crystal residues can be prevented or substantially prevented.

[0066] According to an embodiment, the adhesive layer 20 may have substantially the same width as the first retardation layer 30 .

[0067] Here, the “tear strength” is measured using a sample made of a liquid crystal retardation layer alone or a sample made of two layers of a liquid crystal retardation layer and an alignment film, and for each of the first and second regions, this measurement can be performed according to the following method.

[0068] Methods for measuring tear strength

[0069] The tear strength can be measured according to KS K ISO 13937-2 (Method for measuring tear strength using a trouser-shaped specimen, single tear method). Figure 6 and Figure 7 .

[0070] A sample for tear strength measurement is obtained by laminating a liquid crystal retardation layer 3 on a trouser-shaped substrate (e.g., paper) 1. The substrate 1 includes a region 1a in which the liquid crystal retardation layer 3 is laminated and a region 1b in which the liquid crystal retardation layer is not laminated. The substrate 1 has a trouser-like shape by removing a rectangle having a length (150 ± 2 mm) and a width (2 mm) from the center of a rectangle having a length (200 ± 2 mm) and a width (50 ± 1 mm) in the width direction. The liquid crystal retardation layer 3 has a rectangular shape with a length (150 ± 2 mm) and a width (50 ± 1 mm).

[0071] The sample was mounted on a tensile test device (TA.XTplusC texture analyzer (Stable Micro System)), and the two jigs (upper jig and lower jig) of the tensile test device were clamped to the area 1b where the liquid crystal retardation layer was not stacked. The sample was aligned so that the cutting line of the sample passed through the center line of the sample, and then at 25°C, the area 1b of the sample where the liquid crystal retardation layer was not stacked was vertically engaged with the jig and gripped from the tear test start position 4 (*) to the tear test end position 5 (**) with a total grip length of 100±1mm. When the sample was engaged with the test device, be careful not to tear the area consisting only of the liquid crystal retardation layer and keep the uncut area 1b free on the specimen. Be careful to ensure that the tear extends parallel to the cut portion and that each crotch of the experimental sample is oriented in the direction of the applied force. No initial load was applied at the beginning of the test. The device for recording the tear strength was operated. The test sample is torn to the point marked at the end of the test sample by moving the moving clamp at a tension rate of 300 mm / min. After completion of the test, the average value of the largest peak from the first peak to the last peak is obtained. The first peak area is excluded from the calculation. The peaks suitable for calculation are those that show an increase or decrease in intensity of at least 10%.

[0072] According to an embodiment, in the first retardation layer, the ratio of the tear strength of the liquid crystal non-oriented region to the tear strength of the liquid crystal oriented region [(tear strength of the liquid crystal non-oriented region) / (tear strength of the liquid crystal oriented region)] may be greater than 0 and less than or equal to 0.5, for example, 0.1 to 0.5, 0.1 to 0.4, or 0.1 to 0.3. Within the above range, the appearance of the first retardation layer of the polarizing plate can be improved even when the liquid crystal retardation layer is transferred, and the problem of contamination of the polarizing plate manufacturing process line due to the spread of liquid crystal residues can be prevented or substantially prevented.

[0073] According to an embodiment, in the first retardation layer, the tear strength of the liquid crystal non-aligned area may be less than 0.10 N, for example, greater than or equal to 0 N and less than 0.10 N, 0.01 N to 0.08 N, 0.03 to 0.08 N, or 0.04 to 0.08 N. Within the above range, the polarizing plate manufacturing process and the polarizing plate manufactured thereby may provide the above effects.

[0074] According to an embodiment, in the first retardation layer, the tear strength of the liquid crystal alignment region may be greater than or equal to 0.10 N, for example, 0.10 N to 0.50 N, 0.20 N to 0.40 N, 0.25 to 0.30 N, or 0.25 to 0.27 N. Within the above range, the bonding strength between the liquid crystal molecules in the liquid crystal alignment region is excellent, thereby enhancing the reliability of the first retardation layer.

[0075] exist Figure 1 In the laminate of the base film 100 and the layer 35 for the first retardation layer, the width A of the liquid crystal non-alignment area 35a is not particularly limited, but may be 15 mm to 40 mm in one embodiment.

[0076] although Figure 1 Although not shown in the figure, in the base film 100 on which the layer 35 for the first retardation layer is formed, an alignment film may be further formed between the base film 100 and the layer 35 for the first retardation layer. The alignment film may be conducive to forming the liquid crystal alignment region 32 and the liquid crystal non-alignment region 35a. This will be further described in detail below. According to an embodiment, the width of the layer 35 for the first retardation layer may be the same as the width of the alignment film.

[0077] The first retardation layer includes a liquid crystal non-alignment region formed at two or opposite end portions in a width direction and a liquid crystal alignment region between the liquid crystal non-alignment regions.

[0078] The liquid crystal orientation zone may be a zone in which the liquid crystal molecules are oriented in a specific orientation direction (e.g., a predetermined orientation direction) and a specific tilt angle (e.g., a predetermined tilt angle). Depending on the orientation direction and the tilt angle, the liquid crystal orientation zone may have an in-plane retardation in a specific range (e.g., a predetermined range) at a wavelength of 550 nm. According to an embodiment, due to the presence of the liquid crystal orientation zone, the polarizing plate may be used as an anti-reflective polarizing plate.

[0079] According to an embodiment, the liquid crystal orientation region may have an in-plane delay of 100nm to 200nm (e.g., 100nm to 150nm) at a wavelength of 550nm. According to another embodiment, the liquid crystal orientation region may have an in-plane delay greater than 200nm and less than or equal to 300nm (e.g., 210nm to 275nm) at a wavelength of 550nm. According to another embodiment, the liquid crystal orientation region may have an in-plane delay of less than 100nm (e.g., 0nm to 10nm) at a wavelength of 550nm. In an embodiment, the liquid crystal orientation region may have an in-plane delay of 100nm to 200nm (e.g., 100nm to 150nm) at a wavelength of 550nm.

[0080] According to an embodiment, the liquid crystal alignment region may have a thickness direction retardation less than 0 nm (eg, -60 nm to -30 nm). According to another embodiment, the liquid crystal alignment region may have a thickness direction retardation greater than or equal to 0 nm (eg, 100 nm to 160 nm).

[0081] According to an embodiment, the liquid crystal alignment region may exhibit reverse wavelength dispersibility, forward wavelength dispersibility, or flat wavelength dispersibility as its optical property. Here, "reverse wavelength dispersibility" means that the in-plane delay gradually increases from short wavelength to long wavelength, "forward wavelength dispersibility" means that the in-plane delay gradually decreases from short wavelength to long wavelength, and "flat wavelength dispersibility" means that the in-plane delay has a substantially uniform value when it transitions from short wavelength to long wavelength. In an embodiment, the liquid crystal alignment region may have reverse wavelength dispersibility.

[0082] According to an embodiment, the liquid crystal orientation region may have 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). In an embodiment, the liquid crystal orientation region may have a positive A plate. Here, nx, ny and nz are the refractive indices of the liquid crystal orientation region in the thickness direction, the fast axis direction and the slow axis direction of the liquid crystal orientation region at a wavelength of 550 nm, respectively.

[0083] According to an embodiment, the liquid crystal alignment region may include a cured product of a liquid crystal composition for the liquid crystal alignment region. The cured product of the liquid crystal composition may be formed by treating the liquid crystal composition using thermal curing, photocuring, or a combination thereof.

[0084] The liquid crystal composition may include a polymerizable compound that exhibits liquid crystallinity by polymerization. The polymerizable compound may have one or more polymerizable crosslinking groups. For example, the polymerizable crosslinking group may be a photocurable crosslinking group, which may be an acrylate group, a methacrylate group, a vinyl group, a vinyl oxide group, an epoxy group, an oxetane group, a thiol group, a maleimide group or a variant thereof.

[0085] The liquid crystal composition may further include a polymerizable compound that does not exhibit liquid crystallinity by polymerization but is conducive to forming 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 vinyl oxide group, an epoxy group, an oxetane group, a thiol group, a maleimide group or a variant thereof.

[0086] The liquid crystal composition may further include a liquid crystal compound. The liquid crystal compound may not have one or more polymerizable crosslinking groups, but may facilitate the formation of a liquid crystal retardation layer by being included in the liquid crystal composition.

[0087] The liquid crystal composition may further include additives commonly included for implementing a liquid crystal retardation layer, such as photoinitiators, surface modifiers, antioxidants, etc. The liquid crystal composition may further include a solvent to facilitate the manufacture of a liquid crystal layer having a uniform surface.

[0088] Even when the above-mentioned liquid crystal orientation zone is provided, the liquid crystal non-oriented zone can improve the appearance of both end portions of the first delay layer of the polarizing plate, and prevent or substantially prevent the problem of contamination of the polarizing plate manufacturing line due to delamination of the portion of the liquid crystal non-oriented zone that is not laminated with the adhesive layer and the spreading of liquid crystal residues when the base film is delaminated during the polarizing plate manufacturing process.

[0089] The liquid crystal non-oriented area may be an area in which the liquid crystal molecules are not oriented in a specific orientation direction (e.g., a predetermined orientation direction) and a specific tilt angle (e.g., a predetermined tilt angle). Therefore, the liquid crystal non-oriented area does not contribute to the in-plane delay, wavelength dispersion, and optical properties of the first delay layer. On the contrary, the liquid crystal non-oriented area can improve the appearance of both end portions of the first delay layer of the polarizing plate, and prevent or substantially prevent the problem of contamination of the polarizing plate manufacturing line due to delamination of the portion of the liquid crystal non-oriented area that is not laminated with the adhesive layer and the dispersion of liquid crystal residues when the base film is delaminated during the polarizing plate manufacturing process.

[0090] In an embodiment, 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 using thermal curing, photocuring, or a combination thereof.

[0091] In an embodiment, the liquid crystal composition may include a polymerizable compound that exhibits liquid crystallinity by polymerization. The polymerizable compound may have one or more polymerizable crosslinking groups. For example, the polymerizable crosslinking group may be a photocurable crosslinking group, and the photocurable crosslinking group may be an acrylate group, a methacrylate group, a vinyl group, a vinyl oxide group, an epoxy group, an oxetane group, a thiol group, a maleimide group or a variant thereof.

[0092] The liquid crystal composition may further include a polymerizable compound that exhibits liquid crystallinity without polymerization but is conducive to forming the first retardation layer. In an embodiment, 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 vinyl oxide group, an epoxy group, an oxetane group, a thiol group, a maleimide group or a variant thereof.

[0093] The liquid crystal composition may further include a liquid crystal compound. The liquid crystal compound may not have one or more polymerizable crosslinking groups, but may facilitate the formation of a liquid crystal retardation layer by being included in the liquid crystal composition.

[0094] The liquid crystal composition may further include additives commonly included for implementing a liquid crystal retardation layer, such as photoinitiators, surface modifiers, antioxidants, etc. The liquid crystal composition may further include a solvent to facilitate the manufacture of a liquid crystal layer having a uniform surface.

[0095] In the embodiment, if the total width of the first retardation layer 30 is 100%, the ratio of the width of the liquid crystal non-alignment region formed at the end portion of the first retardation layer (in Figure 2 In the embodiment of the present invention, the ratio of the width B of one liquid crystal non-aligned area 31 to the total width C of the first retardation layer 30 is B / C) can be greater than 0% and less than or equal to 10%, for example, 1% to 10%, or 2% to 8%. Within the above range, the above effect can be achieved without affecting the optical function (including the function of preventing or substantially preventing reflection due to the liquid crystal alignment area in the polarizing plate).

[0096] According to an embodiment, the liquid crystal non-alignment area may be an area having a width of 5 mm to 15 mm (eg, 10 mm to 15 mm) from one end portion of the first retardation layer 30. Figure 2 Within the above range, the effects of the above embodiment can be achieved.

[0097] According to an embodiment, the liquid crystal non-oriented region and the liquid crystal orientation region may be integrated. Here, the term "integrated" may mean that the boundary surface between the liquid crystal non-oriented region and the liquid crystal orientation region is not completely distinguished and remains in a non-flat state. According to an embodiment, the liquid crystal composition for the liquid crystal orientation region is the same as the liquid crystal composition for the liquid crystal non-oriented region, and therefore, the first retardation layer may be manufactured by simultaneously (e.g., synchronously) forming the liquid crystal non-oriented region and the liquid crystal orientation region by a single coating of the liquid crystal composition for the liquid crystal non-oriented region (or the liquid crystal composition for the liquid crystal orientation region).

[0098] In an embodiment, the thickness of the first retardation layer may be greater than 0 μm and less than or equal to 10 μm, for example, 0.1 μm to 10 μm or 0.5 μm to 5 μm. Within the above range, a desired retardation may be achieved.

[0099] The manufacturing method of the first retardation layer is not limited as long as the first retardation layer can include a liquid crystal non-oriented region and a liquid crystal oriented region. However, in order to facilitate the formation of the first retardation layer, the first retardation layer may also include an oriented film on the lower surface of the first retardation layer (i.e., on the surface of the first retardation layer opposite to the polarizer).

[0100] The alignment film is used to align the liquid crystal compound in a desired direction. In addition, the alignment film can control the tear strength of each of the liquid crystal non-aligned region and the liquid crystal aligned region.

[0101] The alignment film may include a first portion and a second portion. The first portion corresponds to the liquid crystal non-alignment region of the first retardation layer. The second portion is located between the first portions and corresponds to the liquid crystal alignment region of the first retardation layer.

[0102] 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 using a composition for forming an alignment film. When a liquid crystal composition is coated on the second part and cured, this may facilitate the formation of a liquid crystal alignment region.

[0103] In an embodiment, the first portion is an alignment film that has not been subjected to an alignment treatment and may include a coating film formed of a composition for forming an alignment film, but may include an uncured uncured product. Even when a liquid crystal composition is coated on the first portion and cured, this can facilitate the formation of a liquid crystal non-aligned region by enabling the liquid crystal to be cured in a non-aligned state.

[0104] According to an embodiment, the first portion and the second portion of the alignment film may be integrated together. Here, the term "integrated" may mean that a boundary surface between the first portion and the second portion is not completely distinguished and remains in a non-flat state.

[0105] According to an embodiment, the alignment film may be formed by single coating of the composition for forming the alignment film to form the first portion and the second portion.

[0106] According to an embodiment, the alignment film may be a friction treatment film made of an organic compound (e.g., a polymer), an oblique deposition film formed of an inorganic compound, a film having microgrooves, or a film obtained by laminating a Langmuir-Blodgett (LB) film prepared using an organic compound (e.g., tricosanoic acid, dioctadecylmethylammonium chloride, and methyl stearate, etc.). In an embodiment, the alignment film may be an alignment film or the like that exhibits an alignment function by irradiating with light. The composition for forming the alignment film may include polyimide, polyvinyl alcohol, modified polyvinyl alcohol, a polymer having a polymerizable group, or the like. The alignment treatment may be performed by rubbing the surface of the polymer layer, by irradiating the photo-aligned material with polarized light or non-polarized light, or by heating the coating of the composition for forming the alignment film.

[0107] According to an embodiment, in the alignment film, when an alignment treatment is performed on a coating film formed by coating a composition for forming an alignment film, the second part and the first part may be formed according to whether the first part and the second part are alignment treated and / or by adjusting the alignment angles in the first part and the second part. This provides a magnitude relationship in terms of tear strength between the liquid crystal alignment region and the liquid crystal non-alignment region in the first retardation layer.

[0108] According to another embodiment, in the alignment film, the second portion may be formed by heat-treating (heat-curing) only the portion of the coating film formed by coating the composition for forming the alignment film, and the first portion may be formed by not heat-treating (heat-curing) the remaining portion. This is beneficial to the magnitude relationship between the liquid crystal alignment region and the liquid crystal non-alignment region in the first retardation layer in terms of tear strength.

[0109] According to another embodiment, in the first retardation layer, the magnitude relationship in tear strength between the liquid crystal alignment region and the liquid crystal non-alignment region may be implemented by adjusting the type of the liquid crystal composition and / or the photocuring degree of the liquid crystal composition.

[0110] In an embodiment, the alignment film may have a thickness greater than 0 μm and less than or equal to 1 μm, for example, 10 nm to 800 nm or 100 nm to 600 nm. Within the above range, a desired retardation may be achieved.

[0111] Polarizer

[0112] The polarizer converts incident natural light or polarized light into linear polarized light in a specific direction, and can be made of a polymer film with a polyvinyl alcohol resin as the main component. In an embodiment, the polarizer can be made by dyeing the polymer film with iodine or dichroic dyes and stretching the dyed polymer film in the machine direction (MD) or by forming polyene bonds on the polymer film by dehydration reaction using an acid catalyst or the like. In an embodiment, the polarizer can be made by a process of swelling, dyeing and stretching the polyvinyl alcohol film, or alternatively, the polarizer can be made by one or more processes such as complementary coloring and cross-linking of the polyvinyl alcohol film.

[0113] The polarizer has a light absorption axis and a light transmission axis in an in-plane direction, and the light absorption axis may be the MD of the polarizer, and the light transmission axis may be the transverse direction (TD) of the polarizer.

[0114] In an embodiment, the polarizer may have a total transmittance of 40% or more (e.g., 40% to 47%) and a degree of polarization of 99% or more (e.g., 95% to 99.9999%). In the above range, the polarizer can improve the anti-reflection performance when combined with the delay layer. "Transmittance" and "polarization degree" are values ​​measured at a wavelength of 380nm to 780nm and are values ​​reflecting the visual sensitivity in the corresponding wavelength range, and can be measured by conventional methods known to those skilled in the art.

[0115] In an embodiment, the polarizer may have a thickness of 2 μm to 30 μm, and in one embodiment may have a thickness of 4 μm to 25 μm, and may be used in a polarizing plate within the above range.

[0116] The polarizing plate may further include an adhesive layer on an upper surface of the first retardation layer (ie, a surface located on one side of the polarizer).

[0117] Adhesive layer

[0118] The adhesive layer is laminated on the surface of the first retardation layer and bonds the first retardation layer to an adherend. Here, the "adherend" may include a polarizer, a protective layer to be described below, or another retardation layer to be described below.

[0119] According to an embodiment, the adhesive layer may be laminated on both the liquid crystal orientation region and the liquid crystal non-orientation region of the first liquid crystal retardation layer. In an embodiment, the adhesive layer may also be bonded to the liquid crystal non-orientation region so that the appearance of both end portions of the first retardation layer can be seen as follows Figure 1 The improvement is achieved by the non-aligned area of ​​liquid crystal shown in FIG.

[0120] According to the embodiment, Figure 1 As for the peel strength of the adhesive layer in the first retardation layer, the peel strength between the adhesive layer and the layer for the first retardation layer or between the adhesive layer and the layer for the first retardation layer and the orientation film may be greater than the peel strength between the base film and the layer for the first retardation layer or between the base film and the layer for the first retardation layer and the orientation film. This can prevent or substantially prevent the peel strength due to the following Figure 1 It is shown that when the base film is layered, liquid crystal residues are spread at both end portions of the first retardation layer to pollute the polarizing plate manufacturing process line, and the appearance at both end portions of the first retardation layer can be improved.

[0121] According to an embodiment, the adhesive layer may be a pressure-sensitive adhesive layer. This can improve processability by providing a high peeling force between the first retardation layer and the adherend while also providing excellent re-peelability. According to an embodiment, the adhesive layer may include a (meth) acrylic adhesive resin, an epoxy adhesive resin, a silicone adhesive resin, a polyurethane adhesive resin, or a polyurethane (meth) acrylic adhesive resin, but the present invention is not limited thereto.

[0122] According to an embodiment, the adhesive layer may have a thickness of 2 μm to 30 μm, and in one embodiment may have a thickness of 4 μm to 25 μm, and may be used in a polarizing plate within the above range.

[0123] The polarizing plate may further include a protective layer located on at least one of the upper surface of the polarizer and the lower surface of the polarizer (eg, between the polarizer and the first retardation layer) and on the lower surface of the first retardation layer. The polarizing plate may include one or more protective layers.

[0124] Protective layer

[0125] The protective layer can provide additional functions for 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 supplementing the thickness of the polarizing plate. In embodiments, the protective layer can prevent or substantially prevent iodine (which can be eluted from the polarizing plate after the polarizing plate is placed under high temperature and high humidity for a long time) from contaminating the retardation layer and / or the panel.

[0126] The protective layer is an optically transparent film, and in an embodiment, may be a film made of one or more resins selected from the following materials: cellulose resins, including triacetylcellulose (TAC) and similar materials; polyester resins, including polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate (PEN), polybutylene naphthalate and similar materials; cyclic polyolefin resins; polycarbonate resins; polyether sulfone resins; polysulfone resins; polyamide resins; polyimide resins, polyolefin resins; polyarylate resins; polyvinyl alcohol resins; polyvinyl chloride resins and polyvinylidene chloride resins.

[0127] According to an embodiment, the protective layer may have a front surface retardation of 10 nm or less (e.g., 0 nm to 5 nm) at a wavelength of 550 nm. In the above range, the effect of using the protective layer can be achieved without affecting the effect of reducing the reflectivity at the front surface and the side surface by the liquid crystal retardation layer.

[0128] In an embodiment, the protective layer may have a thickness of 5 μm to 100 μm, and in one embodiment may have a thickness of 15 μm to 45 μm, and may be used in a polarizing plate within the above range.

[0129] The polarizing plate may further include a second retardation layer, which is located on at least one of the upper surface of the polarizer and the lower surface of the polarizer (for example, between the polarizer and the first retardation layer) and on the lower surface of the first retardation layer. The second retardation layer may refer to a layer having a different retardation value or different optical properties at a wavelength of 550nm compared to the first retardation layer (and in one embodiment, the liquid crystal orientation region of the first retardation layer). The polarizing plate may include one or more second retardation layers.

[0130] Second delay layer

[0131] According to an embodiment, the second retardation layer may have an in-plane retardation of less than 100 nm (e.g., 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 (e.g., 100 nm to 150 nm) at a wavelength of 550 nm. According to another embodiment, the second retardation layer may have an in-plane retardation of greater than 200 nm and less than or equal to 300 nm (e.g., 210 nm to 275 nm) at a wavelength of 550 nm.

[0132] According to an embodiment, the second retardation layer may have a thickness direction retardation less than 0 nm (eg, -60 nm to -30 nm).According to another embodiment, the second retardation layer may have a thickness direction retardation greater than or equal to 0 nm (eg, 100 nm to 160 nm).

[0133] According to an embodiment, the second retardation layer may exhibit reverse wavelength dispersion, forward wavelength dispersion, or flat wavelength dispersion as its optical property.

[0134] According to an embodiment, the second retardation layer may be 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. In an embodiment, the second retardation layer may be a positive C plate.

[0135] 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 made of conventional liquid crystals 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 composition containing a polymer, or may be a coating manufactured by coating a composition containing a polymer.

[0136] According to an embodiment, the second retardation layer may have a thickness less than 3.5 μm (eg, 0.5 μm to 3.4 μm). Within the above range, a desired retardation may be achieved.

[0137] Figure 2 is a cross-sectional view of a polarizing plate according to an embodiment. Figure 2 The polarizing plate includes a polarizer 10, and an adhesive layer 20 and a first retardation layer 30 sequentially stacked on the lower surface of the polarizer 10. The first retardation layer 30 includes a liquid crystal non-orientation area 31 and a liquid crystal orientation area 32, the liquid crystal non-orientation area 31 is formed on two or opposite end portions of the first retardation layer 30 in the width direction, and the liquid crystal orientation area 32 is located between the liquid crystal non-orientation areas 31.

[0138] Figure 3 is a cross-sectional view of a polarizing plate according to another embodiment. Figure 3 The polarizing plate includes a polarizer 10 and an adhesive layer 20, a first retardation layer 30, and an orientation film 40 sequentially stacked on the lower surface of the polarizer 10. The first retardation layer 30 includes a liquid crystal non-orientation area 31 and a liquid crystal orientation area 32, the liquid crystal non-orientation area 31 is formed on two or opposite end portions of the first retardation layer 30 in the width direction, and the liquid crystal orientation area 32 is located between the liquid crystal non-orientation areas 31. The orientation film 40 includes a first portion 41 corresponding to the liquid crystal non-orientation area 31 and a second portion 42 corresponding to the liquid crystal orientation area 32.

[0139] Figure 4 is a cross-sectional view of a polarizing plate according to another embodiment. Figure 4The polarizing plate includes a polarizer 10 and an adhesive layer 20, a first retardation layer 30, an orientation film 40, and a second retardation layer 50 sequentially stacked on the lower surface of the polarizer 10. The first retardation layer 30 includes a liquid crystal non-orientation area 31 and a liquid crystal orientation area 32, the liquid crystal non-orientation area 31 is formed on two or opposite end portions of the first retardation layer 30 in the width direction, and the liquid crystal orientation area 32 is located between the liquid crystal non-orientation areas 31. The orientation film 40 includes a first portion 41 corresponding to the liquid crystal non-orientation area 31 and a second portion 42 corresponding to the liquid crystal orientation area 32.

[0140] Figure 5 is a cross-sectional view of a polarizing plate according to another embodiment. Figure 5 The polarizing plate includes a polarizer 10, a protective layer 60 laminated on the upper surface of the polarizer 10, and an adhesive layer 20, a first retardation layer 30, an orientation film 40, and a second retardation layer 50 sequentially laminated on the lower surface of the polarizer 10. The first retardation layer 30 includes a liquid crystal non-orientation area 31 and a liquid crystal orientation area 32, the liquid crystal non-orientation area 31 is formed on two or opposite end portions of the first retardation layer 30 in the width direction, and the liquid crystal orientation area 32 is located between the liquid crystal non-orientation areas 31. The orientation film 40 includes a first portion 41 corresponding to the liquid crystal non-orientation area 31 and a second portion 42 corresponding to the liquid crystal orientation area 32.

[0141] The optical display device according to one or more embodiments of the present invention includes a polarizing plate according to an embodiment of the present invention. In an embodiment, the optical display device may include any one of an organic light-emitting diode (OLED) display device and a liquid crystal display device.

[0142] In an embodiment, the OLED display device may include an OLED panel, the OLED panel including a flexible substrate stacked on the OLED panel and a polarizing plate according to an embodiment of the present invention. In another embodiment, the OLED display device may include an OLED panel, the OLED panel including a non-flexible substrate stacked on the OLED panel and a polarizing plate according to an embodiment of the present invention.

[0143] Herein, the configuration and operation of the present invention will be further described in detail through some examples of the present invention. However, it should be understood that these examples are provided as examples of the present invention and should not be interpreted as limiting the scope of the present invention in any way.

[0144] Example 1

[0145] A polyvinyl alcohol film (TS#20, Kuraray Co., Ltd., thickness: 20 μm) was stretched six times in an iodine aqueous solution at 55° C. to prepare a polarizer having a total light transmittance of 45%.

[0146] A polyethylene terephthalate (PET) film is prepared as a base film, and a composition for forming an oriented film (comprising a phenolic modified resin and an acrylate monomer containing a phenolic group, Dai Nippon Printing (DNP) Co., Ltd.) is applied to the upper surface of the PET film to a predetermined thickness to form a coating film, and only the remaining portion of the coating film except for two end portions is treated to be oriented at a predetermined orientation angle using a mask, and then thermally cured to form an oriented film.

[0147] A composition for forming a liquid crystal delay layer (including a photocurable melamine-based resin, DNP Co., Ltd.) is applied to the entire surface of the orientation film to a predetermined thickness, and photocured to form a liquid crystal delay layer, thereby preparing a laminate in which a base film, an orientation film and a liquid crystal delay layer are stacked in sequence.

[0148] An acrylic pressure-sensitive adhesive composition (PSA) is applied to the lower surface of the polarizer and the PSA is cured to form an adhesive layer. The prepared adhesive layer is stacked with the liquid crystal delay layer in the laminate. In this case, the width of the adhesive layer is less than the width of the liquid crystal delay layer. After lamination, the base film is layered to produce a polarizing plate in which the polarizer, adhesive layer, liquid crystal delay layer and orientation film are stacked in this order. The liquid crystal delay layer is a positive A plate, and the in-plane delay at a wavelength of 550nm is 125nm.

[0149] A liquid crystal retardation layer (positive C plate) is laminated on the lower surface of the alignment film to produce a polarizing plate in which a polarizer, an adhesive layer, a liquid crystal retardation layer (positive A plate), an alignment film, and a liquid crystal retardation layer (positive C plate) are laminated in this order.

[0150] Instance 2 to Instance 4

[0151] 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 compared to Example 1.

[0152] Comparative Example 1

[0153] A polarizing plate was manufactured in the same manner as in Example 1, except that the entire coating film was subjected to an orientation treatment at a predetermined orientation angle without using a mask and then the entire coating film was thermally cured to prepare an oriented film.

[0154] The following properties were evaluated using the polarizing plates of Example and Comparative Example 1, and the evaluation results are shown in the following Tables 1 and Figure 8 and Fig. 9 middle.

[0155] 1) Tear strength (unit: N): Before laminating the adhesive layer with the laminate composed of the liquid crystal retardation layer (positive A plate) and the alignment film, the tear strength of the laminate composed of the liquid crystal retardation layer (positive A plate) and the alignment film was measured. The tear strength was measured in the same manner for each of the liquid crystal alignment region and the liquid crystal non-alignment region. The tear strength was measured using the above method with reference to Figure 6 and Figure 7 The tear strength was measured according to KS K ISO 13937-2.

[0156] 2) Appearance of both end portions of the liquid crystal retardation layer (positive A plate): The smoothness and uniformity of the cross-section of both end portions of the liquid crystal retardation layer (positive A plate) in the manufactured polarizing plate were visually evaluated. When the cross-section of both end portions of the positive A plate was smooth and uniform, the appearance was evaluated as good, otherwise it was evaluated as poor.

[0157] 3) Whether the residue of the liquid crystal retardation layer (positive A plate) remains on the base film: The base film was laminated in the process of manufacturing the polarizing plate in Example and Comparative Example 1, and then it was evaluated whether the residue of the liquid crystal retardation layer remained on the base film or spread. When the residue of the liquid crystal retardation layer remained on the base film or spread, the presence or absence of the residue was evaluated as poor, otherwise it was evaluated as good.

[0158] Table 1

[0159]

[0160] As shown in Table 1, the appearance of both end portions of the liquid crystal retardation layer is excellent, and the residue does not exist in the liquid crystal retardation layer of the base film (positive A plate) and does not spread, so that the manufacturing processability of the polarizing plate is excellent. On the other hand, in the polarizing plate of Comparative Example 1, the appearance of both end portions of the liquid crystal retardation layer is poor and there is a large amount of residue, and therefore the effect of the embodiment of the present invention cannot be achieved.

[0161] like Figure 8 As shown in , the cross-sections of the liquid crystal retardation layer and the adhesive layer of Example 1 are smooth and uniform. Fig. 9 As shown in , the cross sections of the liquid crystal retardation layer and the adhesive layer of Comparative Example 1 are not uniform.

[0162] Although some exemplary embodiments have been described herein, it will be understood by those skilled in the art that modifications or changes may be easily effected on the embodiments, and therefore, it will be understood that such modifications or changes are included within the scope of the present invention.

Claims

1. A polarizing plate, comprising: Polarizer; as well as A first retardation layer, laminated on the surface of the polarizer, wherein the first retardation layer is a liquid crystal retardation layer, and the first retardation layer includes a plurality of first regions at opposite end portions of the first retardation layer in a width direction and second regions between the first regions, Wherein each of the first regions has a tear strength less than the tear strength of the second regions.

2. The polarizing plate according to claim 1, wherein the first region is a liquid crystal non-alignment region, and The second region is a liquid crystal alignment region.

3. The polarizing plate according to claim 1, wherein a ratio of the tear strength of each of the first regions to the tear strength of the second region is greater than 0 and less than or equal to 0.5, The ratio=(the tear strength of each of the first regions) / (the tear strength of the second region). The polarizing plate according to claim 1 , wherein the tear strength of each of the first regions is less than 0.10N. The polarizing plate according to claim 1 , wherein the tear strength of the second region is 0.10 N or greater.

6. The polarizing plate according to claim 1, wherein If the total width of the first retardation layer is 100%, a ratio of a width of each of the first regions to the total width of the first retardation layer is greater than 0% and less than or equal to 10%. 7 . The polarizing plate according to claim 1 , wherein each of the first regions is a region having a width of 5 mm to 15 mm from one end portion of the first retardation layer. The polarizing plate according to claim 1 , wherein the first retardation layer is a positive A-plate. 9 . The polarizing plate according to claim 1 , further comprising an alignment film on a lower surface of the first retardation layer. 10 . The polarizing plate of claim 9 , wherein the alignment film comprises a plurality of first portions corresponding to the plurality of first regions and a second portion corresponding to the second region.

11. The polarizing plate according to claim 10, wherein the first portion is a portion that has not been subjected to an orientation treatment, and The second portion is an orientation-treated portion. 12 . The polarizing plate according to claim 1 , further comprising an adhesive layer laminated on a 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 different from that of the first retardation layer at a wavelength of 550 nm. The polarizing plate according to claim 13 , wherein the second retardation layer is a positive C-plate. The polarizing plate according to claim 1 , further comprising a protective layer.

16. An optical display device comprising the polarizing plate according to claim 1.

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