WO2024005409A1 - Polarizing plate and optical display device comprising same - Google Patents

Abstract

Provided are a polarizing plate and an optical display device comprising same, the polarizing plate comprising: a polarizer; and a first phase difference layer and a second phase difference layer which are sequentially stacked on the lower surface of the polarizer, wherein the slow axis of the stack of the first phase difference layer and the second phase difference layer forms 111° to 113° with respect to a light transmission axis of the polarizer, and a front linear phase difference value of the stack, measured from the front at a wavelength of 550 nm, is 140 nm to 160 nm, and when the stack is rotated ±40° with the slow axis of the stack as a rotation axis at a wavelength of 550 nm, an inclined linear phase difference value of the stack is 145 nm to 170 nm.

Description

Polarizer and optical display device containing the same

The present invention relates to a polarizing plate and an optical display device including the same.

The visibility and contrast of an organic light emitting display device may be reduced due to reflection of external light. To solve this problem, an anti-reflection function can be implemented by using a polarizer to lower the reflectance of reflected external light. Polarizers are basically required to significantly improve screen quality by improving black visibility from the front.

The polarizer includes a polarizer and an anti-reflection layer laminated on a lower surface of the polarizer. The anti-reflection layer may be a one-sheet type retardation layer or a two-sheet type retardation layer. A single-sheet retardation layer mainly provides reverse wavelength characteristics, and a two-sheet retardation layer mostly provides reverse wavelength characteristics by stacking individual retardation layers each having a normal wavelength phase difference characteristic. There is a possibility that the thickness of the two-sheet type retardation layer will be relatively thicker than that of the one-sheet type retardation layer, but price competitiveness is secured by laminating the existing retardation layer with positive wavelength characteristics, which is cheaper than the one-sheet type retardation layer with reverse wavelength characteristics. and productivity can be improved.

The retardation layer can be manufactured by stretching an unstretched film formed of a composition containing a polymer resin, or by coating liquid crystal to a predetermined thickness on an alignment film and drying and/or curing it. The retardation layer formed from two liquid crystal layers is relatively thinner than the retardation layer formed from two stretched films, but when left under high temperature and high humidity conditions, iodine eluted from the polarizer diffuses into the panel, causing corrosion of the electrode, reducing the durability of the panel. This could be the problem.

The background technology of the present invention is disclosed in Korean Patent Publication No. 10-2013-0103595, etc.

The purpose of the present invention is to provide a polarizing plate with excellent durability as there is no iodine elution after being left at high temperature and high humidity.

Another object of the present invention is to provide a thin polarizing plate.

Another object of the present invention is to provide a polarizer that provides an excellent anti-reflection effect by lowering the reflectance at the front and side.

Another object of the present invention is to provide a polarizer with excellent black visibility.

One aspect of the present invention is a polarizer.

1.Polarizer is a polarizer; and a first retardation layer and a second retardation layer sequentially stacked on the lower surface of the polarizer, wherein the slow axis of the laminate of the first retardation layer and the second retardation layer is 111 with respect to the light transmission axis of the polarizer. ° to 113°, and the front linear phase difference value of the laminate measured from the front at a wavelength of 550 nm is 140 nm to 160 nm, and the laminate is rotated ±40° with the slow axis of the laminate as the rotation axis at a wavelength of 550 nm. The slope linear retardation value is 145 nm to 170 nm.

In 2.1, the first phase difference layer may have a lower thickness than the second phase difference layer.

In 3.1-2, the thickness of the first retardation layer may be 1% to 20% of the thickness of the second retardation layer.

In 4.1-3, the first phase difference layer may be a liquid crystal layer, and the second phase difference layer may be a non-liquid crystal layer.

In 5.4, the liquid crystal layer may be a discotic liquid crystal layer.

In 6.1-5, the non-liquid crystal layer is cellulose-based, polyester-based, cyclic polyolefin (COP)-based, cyclic olefin copolymer (COC)-based, polycarbonate-based, polyethersulfone-based, polysulfone-based, polyamide. It may include a stretched film formed of a composition containing one or more of the following resins: polyimide-based, polyolefin-based, polyarylate-based, polyvinyl alcohol-based, polyvinyl chloride-based, polyvinylidene chloride-based, and acrylic-based resin.

In 7.1-6, the first phase difference layer may have a negative birefringence value, and the second phase difference layer may have a positive birefringence value.

In 8.1-7, the second retardation layer may have a higher degree of biaxiality (NZ) at a wavelength of 550 nm compared to the first retardation layer.

In 9.8, the first phase difference layer may have a biaxiality degree of -0.1 to 0.1 at a wavelength of 550 nm, and the second phase difference layer may have a biaxiality degree of 1 to 1.3 at a wavelength of 550 nm.

In 10.9, the first phase difference layer may have a biaxiality degree of 0 at a wavelength of 550 nm, and the second phase difference layer may have a biaxiality degree of 1 to 1.3 at a wavelength of 550 nm.

11.1-10, the first phase difference layer may be a negative A plate, and the second phase difference layer may be a negative B plate.

12.1-11, the first retardation layer may have a front in-plane retardation of 200 nm to 280 nm at a wavelength of 550 nm, and the second retardation layer may have a front in-plane retardation of 100 nm to 150 nm at a wavelength of 550 nm.

In 13.1-12, the angle formed by the slow axis of the first retardation layer with respect to the light transmission axis of the polarizer may be 10° to 20°.

In 14.1-13, the angle formed by the slow axis of the second retardation layer with respect to the light transmission axis of the polarizer may be 70° to 85°.

In 15.1-14, a buffer layer may be formed on the upper surface of the second phase difference layer.

One aspect of the present invention is an optical display device.

The optical display device includes the polarizing plate of the present invention.

The present invention provides a polarizing plate with excellent durability as there is no iodine elution after being left at high temperature and high humidity.

The present invention provides a thin polarizing plate.

The present invention provides a polarizing plate that provides an excellent anti-reflection effect by lowering the reflectance at the front and side.

The present invention provides a polarizer with excellent black visibility.

1 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention.

Figure 2 shows the maximum reflectance evaluation results from the side (incident angle 60°) of Example 1.

Figure 3 shows the maximum reflectance evaluation results from the side (incident angle of 60°) of Comparative Example 1.

Figure 4 shows the maximum reflectance evaluation results from the side (incident angle of 60°) of Comparative Example 2.

Figure 5 shows the maximum reflectance evaluation results from the side (incident angle of 60°) of Comparative Example 3.

With reference to the attached drawings, the present invention will be described in detail through examples so that those skilled in the art can easily practice it. The present invention may be implemented in many different forms and is not limited to the embodiments described herein.

In order to clearly explain the present invention in the drawings, parts not related to the description are omitted, and the same names are used for identical or similar components throughout the specification. The length and size of each component in the drawings are for illustrative purposes only, and the present invention is not limited to the length and size of each component depicted in the drawings.

In this specification, “upper” and “lower” are defined based on the drawings, and “upper” may be changed to “lower” and “lower” may be changed to “upper” depending on the viewing angle.

The terminology used herein is for the purpose of describing example implementations only and is not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

For the single-layer retardation layer in this specification, “front in-plane retardation (Re)” is expressed by the following formula A, “degree of biaxiality (NZ)” is expressed by the following formula B, and “thickness direction retardation (Rth)” is expressed by the following formula A. " is expressed by the following formula C:

[Formula A]

Re = (nx - ny) × d

[Formula B]

NZ = (nx - nz)/(nx - ny)

[Formula C]

Rth = ((nx + ny)/2 - nz) × d

(In the above formulas A to C, nx, ny, and nz are the refractive indexes in the slow axis direction, fast axis direction, and thickness direction of the single phase difference layer, respectively, at the measurement wavelength, and d is the single phase difference layer thickness (unit: nm).

In this specification, the “Mueller Matrix of the phase difference layer” is expressed by the following equation D, and can be directly measured without difficulty with an Axoscan, which is an example of a phase difference measurement device:

[Formula D]

In this specification, “linear retardation (R _L )” is expressed by the following formula E. Linear phase difference is well known to those skilled in the art, and can be directly measured without difficulty with Axoscan, an example of a phase difference measuring device:

[Formula E]

(In the above formula E, m23, m32, m31, m13, m11, m22 and m33 are values obtained from the above formula D)

In Equations A to E, the measurement wavelength may be 450 nm, 550 nm, or 650 nm.

A laminate containing two retardation layers with different retardation values and slow axes has different characteristics compared to a single layer retardation layer. Therefore, in order to obtain the retardation value measured for the laminate, a different definition is needed compared to the retardation layer of a single layer. The concepts introduced at this time are linear retardation, circular retardation, and total retardation.

A single-layer phase difference layer has the same total phase difference value and linear phase difference value, and there is no circular phase difference value. However, a laminate of two phase difference layers with different physical characteristics (e.g., phase difference value > 0) in terms of phase difference value and slow axis has different linear phase difference values and total phase difference values, and the linear phase difference value is also '0'. This is not the case. In order to calculate phase difference values, a method of calculating the phase difference layer by converting it into a Mueller Matrix can be considered. It can be easily measured using Axoscan (Axometrices, Inc., USA), a Mueller Matrix-based phase difference measurement device.

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'. Since the 'solar axis' and the 'true axis' are generally orthogonal, if you know the angle of the 'solar axis', you can also know the angle of the 'true axis'.

In the case of a single-layer phase contrast layer, measuring and calculating the 'ground axis' is very easy. However, in the case of a laminate in which two phase difference layers with different physical properties (e.g., phase difference value > 0) are stacked, the slow axis of the laminate is calculated by the following equation F:

[Formula F]

(In the above equation F, a1 and a2 are values obtained from the above equation E, respectively)

In this specification, when indicating a numerical range, “X to Y” means greater than X and less than or equal to Y (X≤ and ≤Y).

The polarizing plate of the present invention includes a polarizer; and a first retardation layer and a second retardation layer sequentially laminated on the lower surface of the polarizer.

As will be explained below, the first phase difference layer is a liquid crystal layer. The second retardation layer is a non-liquid crystal layer and is preferably a stretched resin film. Therefore, the polarizing plate of the present invention is a laminate of a retardation layer, and compared to a polarizing plate having a laminate of a liquid crystal layer and a liquid crystal layer, there is no problem such as iodine elution after being left for a long period of time at high temperature and high humidity, so it can be excellent in durability. The 'iodine elution' can be evaluated from the degree to which iodine is decolorized by observing the edge of the polarizing plate under a microscope after leaving the polarizing plate in a high temperature and high humidity (60°C and 90% relative humidity) chamber for 250 hours.

The polarizing plate of the present invention includes a laminate of a liquid crystal layer and a non-liquid crystal layer, which inevitably has a relatively thick thickness compared to a polarizing plate including a laminate of a liquid crystal layer and a liquid crystal layer. However, the laminate of the liquid crystal layer and the non-liquid crystal layer controls both the frontal linear retardation value measured from the front at a wavelength of 550 nm and the inclined linear retardation value when the laminate is rotated ±40° with the slow axis of the laminate as the rotation axis. By doing so, the reflectance from the side was lowered and black visibility was improved. Therefore, the polarizing plate of the present invention can be used as an anti-reflection polarizing plate in a light-emitting display device equipped with a light-emitting device.

The 'front linear retardation value' is calculated when light is incident in the direction normal to the in-plane direction of the first retardation layer while the laminate of the first retardation layer and the second retardation layer is fixed without moving due to rotation, etc. It is a value calculated by equation E.

The 'inclined linear retardation value' is the value of the first phase difference layer in a laminate of a first phase contrast layer and a second phase contrast layer in a state where the slow axis of the laminate is rotated at +40° and -40°, respectively. This is the value calculated by the equation E above when light is incident in the direction normal to the in-plane direction.

The polarizing plate of the present invention includes a polarizer; and a retardation layer stack sequentially laminated on a lower surface of the polarizer, wherein the retardation layer stack includes a first retardation layer and a second retardation layer, and the first retardation layer and the second retardation layer. The slow axis of the laminate is 111° to 113° with respect to the light transmission axis of the polarizer, the laminate has a front linear retardation value of 140 nm to 160 nm measured from the front at a wavelength of 550 nm, and the laminate has a When rotated ±40° using the slow axis as the rotation axis, the inclined linear phase difference value is 145 nm to 170 nm.

Hereinafter, a polarizing plate of an embodiment of the present invention will be described with reference to FIG. 1.

Referring to FIG. 1, the polarizer includes a polarizer 130, a protective film 140 laminated on the upper surface of the polarizer 130, and a retardation layer stack laminated on the lower surface of the polarizer 130.

In this specification, the 'upper surface of the polarizer' is the surface on which external light is first incident on the polarizer or the surface on which light emitted from the light emitting device is emitted through the polarizer.

In this specification, the 'lower surface of the polarizer' is the surface on which light emitted from the light emitting device is incident on the polarizer or the surface on which external light is first emitted after being incident on the polarizer.

In one embodiment, as shown in FIG. 1, the retardation layer laminate is a two-layer retardation layer consisting of a first retardation layer 110 and a second retardation layer 120 sequentially stacked from the lower surface of the polarizer 130. It may be a stack of layers.

In another embodiment, the retardation layer stack includes a first retardation layer and a second retardation layer sequentially stacked from the lower surface of the polarizer, between the polarizer and the first retardation layer, and between the first retardation layer and the second retardation layer. , and/or a base layer may be further laminated on the lower surface of the second retardation layer. The base layer supports each of the first retardation layer and the second retardation layer, and may be a retardation film with no retardation or a front in-plane retardation of 30 nm or less at a wavelength of 550 nm, specifically 0 nm to 10 nm.

The protective film 140 may correspond to one specific example of a protective layer including a protective coating layer. If there is no problem with the function of the polarizer, the protective film 140 may be omitted.

Although not shown in FIG. 1, an adhesive layer or adhesive layer may be additionally laminated on the lower surface of the second retardation layer 120 to adhere the polarizer to the optical display panel.

The first retardation layer 110 and the second retardation layer 120 are stacked on the lower surface of the polarizer to provide an anti-reflection effect by circularly polarizing linearly polarized external light emitted through the polarizer.

The first phase difference layer 110 may be a liquid crystal layer, and the second phase difference layer 120 may be a non-liquid crystal layer. The polarizing plate of the present invention has excellent durability because it does not have problems such as iodine elution compared to a polarizing plate having a laminate of a liquid crystal layer and a liquid crystal layer as a retardation layer, and is composed of a resin film of a non-liquid crystal layer and a resin film of a non-liquid crystal layer as a retardation layer. A thinner effect can be realized compared to a polarizer having a laminate.

The liquid crystal layer for the first phase difference layer 110 may include a wide disk-shaped liquid crystal. For example, the liquid crystal may include a monomer, an oligomer, or a polymer.

The liquid crystal layer may include reactive mesogen liquid crystal. For example, the liquid crystal may have one or more reactive crosslinking groups. The reactive mesogenic liquid crystal is, for example, a rod-shaped aromatic derivative having one or more reactive crosslinking groups, propylene glycol 1-methyl, propylene glycol 2-acetate, and a compound represented by P1-A1-(Z1-A2)n-P2 (where P1 and P2 each independently include acrylate, methacrylate, vinyl, vinyloxy, epoxy, or a combination thereof, and A1 and A2 each independently include 1. , 4-phenylene (1,4-phenylene), naphthalene (naphthalene)-2,6-diyl (diyl) group or a combination thereof, Z1 is a single bond, -COO-, -OCO- or these It may include at least one of combinations, and n is 0, 1, or 2), but is not limited thereto.

The liquid crystal layer may be formed of a composition for a liquid crystal layer that further includes commonly included additives, such as a photoinitiator and a surface control agent, in addition to the above-mentioned reactive mesogen liquid crystal. The composition for the liquid crystal layer may include a solvent to facilitate the manufacture of a liquid crystal layer with a uniform surface.

Preferably, the liquid crystal layer may include a discotic liquid crystal layer. The discotic liquid crystal layer has a degree of biaxiality within a predetermined range, making it easier to lower the reflectance on the side and improve black visibility in the laminate of the first and second retardation layers of the present invention.

The first phase difference layer 110 has a degree of biaxiality (NZ) of -0.1 to 0.1 at a wavelength of 550 nm, for example -0.1, -0.09, -0.08, -0.07, -0.06, -0.05, -0.04, -0.03, It may be -0.02, -0.01, 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, preferably -0.05 to 0.05, and more preferably 0. Within the above range, it may be easier to lower the reflectance on the side and improve black visibility in the laminate of the first and second retardation layers of the present invention.

The first phase difference layer 110 has constant wavelength dispersion, and Re (450) > Re (550) > Re (650) [Re (450), Re (550), and Re (650) are each of the first phase difference layer. [It is the frontal in-plane phase difference at wavelengths of 450nm, 550nm, and 650nm]. Through this, the laminate of the first retardation layer and the second retardation layer exhibits reverse wavelength dispersion, so that the polarizer can significantly lower the reflectance on the front and side surfaces, improving black visibility and improving screen quality.

The first phase difference layer 110 may be a negative A plate having a refractive index relationship nx≒nz>ny. Here, nx, ny, and nz are the refractive index in the slow axis direction, the refractive index in the fast axis direction, and the thickness direction of the first retardation layer, respectively, at a wavelength of 550 nm.

The first phase difference layer 110 has a front in-plane phase difference at a wavelength of 550 nm compared to the second phase difference layer, and is 200 nm to 280 nm, for example, 200, 210, 220, 230, 240, 250, 260, 270, 280 nm, preferably It can be 220nm to 260nm. Within the above range, it can be easy to significantly lower the reflectance from the front and sides to improve black visibility and increase screen quality.

The first phase difference layer 110 has a slow axis and a fast axis in the in-plane direction. The angle formed by the slow axis of the first retardation layer with respect to the light transmission axis of the polarizer is 10° to 20°, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20°, Preferably it may be 15° to 19°. Within the above range, it can be easy to significantly lower the reflectance from the front and sides to improve black visibility and increase screen quality.

The first phase difference layer 110 has a significantly lower thickness than the second phase difference layer 120. This is because the first retardation layer 110 is manufactured by applying a liquid crystal layer composition to a predetermined thickness, as will be explained below, while the second retardation layer 120 is manufactured from a resin film. In one embodiment, the thickness of the first retardation layer 110 is 1% to 20% of the thickness of the second retardation layer 120, for example, 1, 2, 3, 4, 5, 6, 7, 8, It may be 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20%, preferably 10% to 20%.

The first phase difference layer 110 may have a thickness of 1㎛ to 5㎛, preferably 2㎛ to 3㎛. Within the above range, the above-described phase difference can be implemented.

The first retardation layer 110 may be manufactured by applying the above-described liquid crystal layer composition to the upper surface of the second retardation layer to a predetermined thickness and then drying and/or curing it. In one embodiment, the first phase difference layer 110 may be formed directly on the second phase difference layer. The term 'directly formed' means that no adhesive layer, adhesive layer, or adhesive layer is formed between the first phase difference layer and the second phase difference layer.

The second retardation layer may further include an alignment film on the upper surface to form the first retardation layer, as described below.

The first phase difference layer may have negative birefringence, and the second phase difference layer may have positive birefringence.

The second phase difference layer 120 is a non-liquid crystal layer. The second retardation layer 120 not only provides the anti-reflection effect of the present invention together with the first retardation layer, but can also be used as a base film or support to form the first retardation layer. The 'non-liquid crystal' is not one or more of liquid crystal monomers, liquid crystal oligomers, and liquid crystal polymers, and may include materials that are not converted into liquid crystal monomers, liquid crystal oligomers, or liquid crystal polymers by light irradiation or heat treatment.

The second phase difference layer 120 is a cellulose-based material including triacetylcellulose, polyester-based material including polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate (PET), polybutylene naphthalate, and cyclic polyolefin. (COP)-based, cyclic olefin copolymer (COC)-based, polycarbonate-based, polyethersulfone-based, polysulfone-based, polyamide-based, polyimide-based, polyolefin-based, polyarylate-based, polyvinyl alcohol-based, polychlorinated It may include a stretched film formed of a composition containing one or more of vinyl-based, polyvinylidene chloride-based, and acrylic-based resins. Preferably, in order to facilitate the implementation of wavelength dispersion and phase difference described below, a cyclic polyolefin-based resin may be included. Cyclic polyolefin-based resin can facilitate the implementation of the effects of the present invention.

The second phase difference layer 120 may have a significantly higher thickness than the first phase difference layer 110. In one embodiment, the second retardation layer 120 may have a thickness of 15 ㎛ to 35 ㎛, preferably 15 ㎛ to 25 ㎛. Within the above range, it can provide a phase difference of the second phase difference layer described below and function as a base film or support.

The second phase contrast layer 120 may have a higher degree of biaxiality (NZ) than the first phase contrast layer 110 at a wavelength of 550 nm. Through this, it can be easy to provide the effects of improving reflectance and light leakage and improving black visibility of the present invention.

In one embodiment, the second phase difference layer 120 has a degree of biaxiality of 1 or more and less than 1.3 at a wavelength of 550 nm, for example, 1, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.1, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.2, 1.21, 1.22, 1.23, 1.24, 1.25, 1.26, 1.27, 1.28, 1.29, preferably 1.05 to 1. .25, more preferably 1.05 to 1.2, most preferably 1.1 to 1.15. In the above range, it is possible to easily reach the front and oblique linear retardation ranges of the laminate of the first retardation layer and the second retardation layer of the present invention, reduce reflectance and light leakage from the side, and improve black visibility. .

The second phase difference layer 120 is flat or has a constant wavelength dispersion, and Re (450) ≥ Re (550 ≥ Re (650) [Re (450), Re (550), and Re (650) are each the second phase difference layer. is the front in-plane phase difference at the wavelengths of 450 nm, 550 nm, and 650 nm.] Through this, the laminate of the first phase contrast layer and the second phase contrast layer exhibits reverse wavelength dispersion, so that the polarizer can be By significantly lowering the reflectance, black visibility can be improved and screen quality can be improved.

The second phase difference layer 120 may be a negative B plate having a refractive index relationship of nx>ny>nz. Here, nx, ny, and nz are the refractive index in the slow axis direction, the refractive index in the fast axis direction, and the thickness direction, respectively, of the second retardation layer at a wavelength of 550 nm.

The second phase difference layer 110 has a front in-plane phase difference lower than that of the first phase difference layer at a wavelength of 550 nm, and is 100 nm to 150 nm, for example, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, It may be 150 nm, preferably 110 nm to 130 nm. Within the above range, it can be easy to significantly lower the reflectance from the front and sides to improve black visibility and increase screen quality.

The second phase difference layer 120 has a slow axis and a fast axis in the in-plane direction. The angle formed by the slow axis of the second retardation layer 120 with respect to the light transmission axis of the polarizer is 70° to 85°, for example, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, It may be 80, 81, 82, 83, 84, 85°, preferably 75° to 80°. Within the above range, it can be easy to significantly lower the reflectance from the front and sides to improve black visibility and increase screen quality.

In one embodiment, the angle formed by the slow axis of the first phase difference layer 110 and the slow axis of the second phase difference layer 120 is 50° to 80°, for example, 50, 51, 52, 53, 54, 55. , 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80 °, preferably 55° to 75°. Within the above range, it can be easy to implement the effects of the present invention.

The second retardation layer 120 may be manufactured by stretching an unstretched film for the second retardation layer by MD 1-axis, TD 1-axis, oblique stretching, or a combination thereof. The stretching method can be performed by conventional methods known to those skilled in the art.

The second phase difference layer 110 may further include an alignment film for forming the first phase difference layer 110 on its upper surface. The alignment layer may be formed of a common composition for forming an alignment layer known to those skilled in the art. The alignment film can be manufactured by applying the composition for forming an alignment film to a predetermined thickness and then physically aligning it by rubbing, or by applying the composition for forming an alignment film to a predetermined thickness and then photo-aligning it.

The laminate of the first phase difference layer 110 and the second phase difference layer 120 may exhibit reverse wavelength dispersion. Through this, it can be easy to significantly lower the reflectance from the front and sides to improve black visibility and increase screen quality. Reverse wavelength dispersion means that the short wavelength dispersion of the laminate of the first phase difference layer 110 and the second phase difference layer 120 has a lower value than the long wavelength dispersion. The 'reverse wavelength dispersion' means that the laminate has the following relationship: inclined linear phase difference at a wavelength of 450 nm < inclined linear phase difference at a wavelength of 550 nm < inclined linear phase difference at a wavelength of 650 nm. However, in the case of a linear phase difference at the front of the laminate, it may have a value of R _L (550) < R _L (450) < R _L (650). R _L (450), R _L (550), and R _L (650) are the front linear retardation values of the laminate at wavelengths of 450 nm, 550 nm, and 650 nm, respectively.

The slow axis of the laminate of the first retardation layer 110 and the second retardation layer 120 forms an angle of 111° to 113° with respect to the light transmission axis of the polarizer, and the first retardation layer 110 The laminate of the second phase difference layer 120 has a front linear phase difference value of 140 nm to 160 nm, measured from the front at a wavelength of 550 nm, and the laminate is rotated ±40° with the slow axis of the laminate as a rotation axis at a wavelength of 550 nm. When applied, the slope linear retardation value is 145 nm to 170 nm. By satisfying all of the angle range, the front linear phase difference value, and the inclined linear phase difference value, reflectance at the front and sides can be lowered to provide an excellent anti-reflection effect and excellent black visibility. If any one of the angle range, the front linear phase difference value, and the oblique linear phase difference value does not satisfy the range of the present invention, the anti-reflection effect and the black visibility improvement effect of the present invention may be significantly reduced.

In one embodiment, the slow axis of the laminate may be 111, 111.5, 112, 112.5, or 113° with respect to the light transmission axis of the polarizer.

In one embodiment, the laminate has a front-on linear retardation value, measured from the front at a wavelength of 550 nm, of 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, It can be 154, 155, 156, 157, 158, 159, 160nm.

In one embodiment, the laminate has an inclined linear retardation value of 145, 146, 147, 148, 149, 150, 151, 152, 153 when rotated ±40° with the slow axis of the laminate as the rotation axis at a wavelength of 550 nm. It can be 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 167, 168, 169, 170 nm.

The front phase difference or in-plane phase difference referred to in a laminate of conventional retardation layers is a phase difference measured in the direction normal to the in-plane direction of the laminate. The present invention adjusts the slow axis angle with respect to the laminate having the first phase difference layer 110 and the second phase difference layer 120 of the present invention described above, and not only the phase difference measured in the normal direction with respect to the in-plane direction of the laminate In addition, by controlling both the tilt phase difference measured when the slow axis of the laminate is rotated, both the anti-reflection effect and the black visibility improvement effect are improved. In one embodiment, the first liquid crystal layer may be a liquid crystal layer, preferably a discotic liquid crystal layer, and the second liquid crystal layer may be a non-liquid crystal layer, preferably a stretched film or a stretched coating layer. In one embodiment, the first liquid crystal layer may have a biaxiality degree (NZ) of -0.1 to 0.1 at a wavelength of 550 nm, and the second liquid crystal layer may have a biaxiality degree (NZ) of 1 to 1.3 at a wavelength of 550 nm. In one embodiment, the first phase difference layer may be a negative A plate and the second phase difference layer may be a negative B plate.

The two linear retardation values of the laminate can be implemented by adjusting the front in-plane retardation of each of the first retardation layer and the second retardation layer, the slow axis relationship between the first retardation layer and the second retardation layer, etc.

The first retardation layer 110 may be formed by coating one surface of the second retardation layer 120 with a first retardation layer composition, that is, a liquid crystal layer composition, to a predetermined thickness and then drying and/or curing it.

In one embodiment, the liquid crystal layer composition is applied to one surface of the second retardation layer to a predetermined thickness. In this process, one surface of the second retardation layer is eroded by the solvent contained in the liquid crystal layer composition and becomes a buffer layer. This can be formed.

The polarizer 130 converts incident natural light or polarized light into linearly polarized light in a specific direction, and may be manufactured from a polymer film containing polyvinyl alcohol-based resin as a main component. Specifically, the polarizer 110 can be manufactured by dyeing the polymer film with iodine or a dichroic dye and stretching it in MD (machine direction). Specifically, it can be manufactured through a swelling process, a dyeing step, a stretching step, and a cross-linking step.

The polarizer 130 has a light absorption axis and a light transmission axis in the in-plane direction. The light absorption axis may be the MD of the polarizer, and the light transmission axis may be the TD of the polarizer.

The polarizer 130 may have a light transmittance of 40% or more, for example, 40% to 46%, and a polarization degree of 95% or more, for example, 95% to 99.9%. Within the above range, anti-reflection performance can be improved when combined with the first phase difference layer and the second phase difference layer. The “light transmittance” and “polarization degree” are values reflecting visibility at a wavelength of 380 nm to 780 nm.

The polarizer 130 may have a thickness of 2㎛ to 30㎛, specifically 4㎛ to 25㎛, and can be used in the polarizing plate within this range.

Although not shown in FIG. 1, the polarizer 130 may be bonded to a laminate of the first phase difference layer and the second phase difference layer by an adhesive layer. The adhesive layer may be formed of one or more of a water-based adhesive and a photocurable adhesive. Preferably, the adhesive layer is formed of a photocurable adhesive, so that adhesion between the protective film and the polarizer and between the polarizer and the first phase difference layer can be achieved by a single irradiation of light, thereby improving the manufacturing process of the polarizer. The first adhesive layer may have a thickness of 0.1 ㎛ to 10 ㎛, specifically 0.5 ㎛ to 5 ㎛. Within the above range, it can be used in a polarizing plate.

The protective film 140 may be formed on the upper surface of the polarizer 130, thereby protecting the polarizer from the external environment and increasing the mechanical strength of the polarizer.

The protective film 140 protects the polarizer from the external environment and is an optically transparent film, for example, cellulose-based including triacetylcellulose (TAC), polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene oxide. Polyester-based, cyclic polyolefin-based, polycarbonate-based, polyethersulfone-based, polysulfone-based, polyamide-based, polyimide-based, polyolefin-based, polyarylate-based, including phthalate (PEN), polybutylene naphthalate, etc. It may be a film made of one or more of polyvinyl alcohol-based, polyvinyl chloride-based, and polyvinylidene chloride-based resins. Specifically, TAC and PET films can be used.

The protective film 140 may have a thickness of 5㎛ to 70㎛, specifically 15㎛ to 45㎛, and can be used in the polarizing plate within this range.

Although not shown in FIG. 1, a functional coating layer is formed on the upper surface of the protective film 140 to provide additional functions to the polarizer. For example, the functional coating layer includes a hard coating layer, an anti-fingerprint layer, an anti-reflection layer, and an anti-glare layer. etc., and they may be formed singly or by stacking two or more types.

Although not shown in FIG. 1, the protective film 140 may be attached to the polarizer 110 through an adhesive layer. The adhesive layer may be formed of one or more of a water-based adhesive and a photocurable adhesive.

The adhesive layer may have a thickness of 0.1 ㎛ to 10 ㎛, specifically 0.1 ㎛ to 5 ㎛. Within the above range, it can be used in a polarizing plate.

The optical display device of the present invention includes the polarizing plate of the embodiment of the present invention. Optical displays may include organic light emitting diode (OLED) displays and liquid crystal displays.

In one embodiment, an organic light emitting device display device may include an organic light emitting device panel including a flexible substrate, and a polarizing plate of the present invention stacked on the organic light emitting device panel.

In another embodiment, an organic light emitting device display device may include an organic light emitting device panel including a non-flexible substrate, and a polarizing plate of the present invention stacked on the organic light emitting device panel.

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, this is presented as a preferred example of the present invention and should not be construed as limiting the present invention in any way.

Example 1

A polyvinyl alcohol-based film (PS#60, Kuraray, Japan, thickness before stretching: 60㎛) was stretched 6 times along the MD of the film in an iodine aqueous solution at 55°C to prepare a polarizer with a light transmittance of 45%.

An unstretched cyclic polyolefin (COP)-based film was prepared, and oblique stretching and MD stretching were sequentially performed on the MD of the film to prepare a second retardation layer (negative B plate).

An alignment film is formed on the upper surface of the manufactured second retardation layer, the composition for the discotic liquid crystal layer is applied and then cured, and a first retardation layer (negative A plate, positive wavelength), which is a discotic liquid crystal layer, is formed on the upper surface of the second retardation layer. A laminate of a first phase difference layer and a second phase difference layer, in which dispersibility) was laminated, was manufactured.

An HC-TAC film (Toppan, 25FJCHCN-TC, thickness: 32㎛) was laminated as a protective film on the upper surface of the prepared polarizer, and a laminate of the first and second retardation layers was laminated on the lower surface of the polarizer. A polarizing plate was manufactured by (a first retardation layer and a second retardation layer were sequentially stacked on the lower surface of the polarizer).

Examples 2 to 4

In Example 1, except that the stretching ratio, stretching temperature, etc. were changed when manufacturing the second retardation layer, and the thickness, etc. was changed when manufacturing the first retardation layer, so that the first retardation layer and the second retardation layer were changed as shown in Table 1 below. A polarizing plate was manufactured by performing the same method as Example 1.

Comparative Examples 1 to 3

In Example 1, except that the stretching ratio, stretching temperature, etc. were changed when manufacturing the second retardation layer, and the thickness, etc. was changed when manufacturing the first retardation layer, so that the first retardation layer and the second retardation layer were changed as shown in Table 1 below. A polarizing plate was manufactured by performing the same method as Example 1.

Re and NZ of each of the first and second phase difference layers are values obtained at a wavelength of 550 nm using AXOSCAN.

The following physical properties were evaluated using the laminates and polarizers of Examples and Comparative Examples and are shown in Table 1 and Figures 2 to 5 below.

(1) Front linear retardation value and inclined linear retardation value of the laminate (unit: nm, @550nm): a Mueller Matrix-based measuring device for the laminate of the first and second retardation layers of the examples and comparative examples. Measured with Axoscan.

(2) Iodine elution: The polarizing plates prepared in Examples and Comparative Examples were left in a high-temperature, high-humidity (60°C and 90% relative humidity) chamber for 250 hours, and then the edges of the polarizing plates were observed under a microscope to compare and evaluate the degree of iodine decolorization.

(3) Reflectance from the side: When the reflectance of external light incident on the inside, excluding primary reflection, was measured in all directions using the simulation program Techwiz 1D (Sanai System, Korea) for the polarizers manufactured in Examples and Comparative Examples. The reflectance value in the direction of maximum was calculated. It is desirable for the reflectance to be less than 6%, preferably less than 5.6%.

(4) Black visual perception: The polarizers manufactured in Examples and Comparative Examples were attached to an aluminum plate using an adhesive and visually evaluated for visual perception. If blue and/or yellow were not visible and appeared completely black, it was rated as 'excellent'.

		Example				Comparative example
		One	2	3	4	One	2	3
1st phase difference layer	Re(nm)	240	240	240	240	240	240	240
	NZ	0	0	0	0	0	0	0
	thickness (㎛)	2.5	2.5	2.5	2.5	2.5	2.5	2.5
2nd phase difference layer	Re(nm)	120	125	110	120	110	130	140
	NZ	1.1	1.1	1.1	1.2	1.3	1.3	1.1
	thickness (㎛)	21	23	19	21	19	23	25
angle 1		17.5°	17.5°	17.5°	17.5°	17.5°	17.5°	17.5°
angle 2		78°	79°	78°	78°	75.5°	78°	78°
Front linear retardation value of the laminate (nm)		150.4	143.7	159.5	150.4	164.9	141.1	131.6
ground axis angle		111.9°	112.1°	111.4°	111.9°	111.5°	112.5°	113.2°
Inclined linear retardation value of the laminate (nm)		159.0	151.7	169.3	157.1	171.0	144.6	137.9
iodine elution		doesn't exist	doesn't exist	doesn't exist	doesn't exist	doesn't exist	doesn't exist	doesn't exist
Maximum reflectance from the side (angle of incidence 60°)		4.1%	5.5%	5.6%	4.9%	6.8%	10.4%	12.0%
Black Persimmon		Great	Great	Great	Great	Blue poet is strong	yellow poet is strong	yellow poet is strong

*In Table 1,

① Slow axis angle: The angle formed by the slow axis of the laminate based on the light transmission axis of the polarizer, which can be obtained using the equation E and F above.

②Angle 1: The angle formed by the slow axis of the first retardation layer based on the light transmission axis of the polarizer

③Angle 2: The angle formed by the slow axis of the second retardation layer based on the light transmission axis of the polarizer

As shown in Table 1, the polarizing plate of the present invention was excellent in durability without iodine elution, had a significant effect of improving reflectance and light leakage from the side, and had excellent black visibility.

On the other hand, Comparative Examples 1 and 2, which were outside the phase difference ranges for the frontal linear phase difference and oblique linear phase difference at the wavelength of 550 nm of the present invention, had a problem in that black vision was significantly reduced. In Comparative Example 3, which deviated from the slow axis angle of the present invention, the effect of improving reflectance and light leakage from the side and the effect of improving black visibility were weak.

As shown in Figure 2, the polarizer of the example provided excellent black visibility from the side and low reflectance. On the other hand, as shown in Figures 3 to 5, it can be confirmed that the polarizer of the comparative example had a strong yellow or red color, resulting in poor black visibility and a high reflectance.

Simple modifications or changes to the present invention can be easily implemented by those skilled in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims (16)

1. polarizer; and a first retardation layer and a second retardation layer sequentially stacked on the lower surface of the polarizer,

   The slow axis of the laminate of the first retardation layer and the second retardation layer is 111° to 113° with respect to the light transmission axis of the polarizer,

   The laminate has a frontal linear retardation value of 140 nm to 160 nm measured from the front at a wavelength of 550 nm, and the inclined linear retardation value of the laminate is 145 nm to 160 nm when rotated ±40° with the slow axis of the laminate as a rotation axis at a wavelength of 550 nm. Polarizer, which is 170nm.
2. The polarizing plate of claim 1, wherein the first retardation layer has a lower thickness than the second retardation layer.
3. The polarizing plate of claim 1, wherein the thickness of the first retardation layer is 1% to 20% of the thickness of the second retardation layer.
4. The polarizing plate of claim 1, wherein the first retardation layer is a liquid crystal layer, and the second retardation layer is a non-liquid crystal layer.
5. The polarizing plate of claim 4, wherein the liquid crystal layer is a discotic liquid crystal layer.
6. The method of claim 4, wherein the non-liquid crystal layer is cellulose-based, polyester-based, cyclic polyolefin (COP)-based, cyclic olefin copolymer (COC)-based, polycarbonate-based, polyethersulfone-based, polysulfone-based, poly Comprising a stretched film formed of a composition containing one or more of amide-based, polyimide-based, polyolefin-based, polyarylate-based, polyvinyl alcohol-based, polyvinyl chloride-based, polyvinylidene chloride-based, and acrylic-based resins, Polarizer.
7. The polarizing plate of claim 1, wherein the first phase difference layer has a negative birefringence value, and the second phase difference layer has a positive birefringence value.
8. The polarizing plate of claim 1, wherein the second retardation layer has a higher degree of biaxiality (NZ) at a wavelength of 550 nm compared to the first retardation layer.
9. The polarizing plate of claim 8, wherein the first retardation layer has a biaxiality degree of -0.1 to 0.1 at a wavelength of 550 nm, and the second retardation layer has a biaxiality degree of 1 to 1.3 at a wavelength of 550 nm.
10. The polarizing plate of claim 9, wherein the first retardation layer has a biaxiality degree of 0 at a wavelength of 550 nm, and the second retardation layer has a biaxiality degree of 1 to 1.3 at a wavelength of 550 nm.
11. The polarizing plate of claim 1, wherein the first retardation layer is a negative A plate, and the second retardation layer is a negative B plate.
12. The polarizing plate of claim 1, wherein the first retardation layer has a front in-plane retardation of 200 nm to 280 nm at a wavelength of 550 nm, and the second retardation layer has a front in-plane retardation of 100 nm to 150 nm at a wavelength of 550 nm.
13. The polarizing plate of claim 1, wherein the angle formed by the slow axis of the first retardation layer with respect to the light transmission axis of the polarizer is 10° to 20°.
14. The polarizing plate of claim 1, wherein an angle formed by the slow axis of the second retardation layer with respect to the light transmission axis of the polarizer is 70° to 85°.
15. The polarizing plate of claim 1, wherein a buffer layer is formed on the upper surface of the second retardation layer.
16. An optical display device comprising the polarizing plate of any one of claims 1 to 15.

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