阅读说明：本技术 偏光板与包含其的液晶显示装置 (Polarizing plate and liquid crystal display device comprising same ) 是由 郑容云 吴泳 魏东镐 朱荣贤 于 2018-05-14 设计创作，主要内容包括：提供一种偏光板及包含其的液晶显示装置,偏光板包括依序积层的偏光膜、对比度增强层及抗反射膜。抗反射膜的最小反射率不大于0.45％。抗反射膜具有依序积层于对比度增强层上的第一基底层、高折射率层及低折射率层。对比度增强层包括第一树脂层及面对所述第一树脂层的第二树脂层。第二树脂层包括图案化部分,所述图案化部分具有光学图案及光学图案之间的平坦部分。图案化部分满足方程式1,光学图案具有75°至90°的底角(θ)。偏光板根据方程式2的反射率斜率为不大于0.3。(Provided are a polarizing plate and a liquid crystal display device including the same, the polarizing plate including a polarizing film, a contrast enhancing layer and an anti-reflection film laminated in this order. The minimum reflectance of the antireflection film is not more than 0.45%. The antireflection film has a first base layer, a high refractive index layer and a low refractive index layer laminated in this order on a contrast enhancement layer. The contrast enhancement layer includes a first resin layer and a second resin layer facing the first resin layer. The second resin layer includes a patterned portion having optical patterns and a flat portion between the optical patterns. The patterned portion satisfies equation 1, and the optical pattern has a base angle (θ) of 75 ° to 90 °. The reflectance slope of the polarizing plate according to equation 2 is not more than 0.3.)

1. A polarizing plate comprises a polarizing film, a contrast enhancing layer and an antireflection film laminated in this order,

the anti-reflection film has a minimum reflectance of 0.45% or less than 0.45%,

the antireflection film includes a first base layer, a high refractive index layer and a low refractive index layer laminated in this order on the contrast enhancing layer,

the contrast enhancing layer includes a first resin layer and a second resin layer facing the first resin layer, wherein the second resin layer includes a patterned portion including a plurality of optical patterns and a flat portion formed between the plurality of optical patterns,

the patterned portion satisfies the following equation 1,

each of the plurality of optical patterns has a base angle (θ) of 75 ° to 90 °:

< equation 1>

1＜P/B≤6

(in equation 1, P is the pitch (unit: micrometer) of the patterned portion, and

b is the maximum width (unit: micrometer) of the flat portion),

the polarizing plate has a reflectance slope of 0.3 or less than 0.3 according to the following equation 2:

< equation 2>

Reflectivity slope R₆₀₀-R₅₀₀|/|600-500|×100

(in equation 2, R₆₀₀Is a reflectance value of the polarizing plate at a wavelength of 600 nm, and

R₅₀₀is the reflectance value of the polarizing plate at a wavelength of 500 nm).

2. The polarizing plate of claim 1, wherein the polarizing plate has a light reflectance of 2% or less than 2%.

3. The polarizing plate of claim 1, wherein the polarizing film comprises a polarizer and a protective layer formed on at least one surface of the polarizer, and wherein the protective layer comprises at least one of a protective film and a protective coating.

4. The polarizing plate of claim 1, wherein an absolute value of a difference in refractive index between the first resin layer and the second resin layer is 0.05 to 0.20.

5. The polarizing plate of claim 1, wherein the refractive index of the second resin layer is higher or lower than the refractive index of the first resin layer.

6. The polarizing plate of claim 1, wherein each of the plurality of optical patterns comprises an engraved pattern comprising a first surface at the top and at least one inclined surface connected to the first surface, the inclined surface comprising a flat or curved optical pattern.

7. The polarizing plate of claim 6, wherein the first surface is flat and formed parallel to the flat portion.

8. The polarizing plate of claim 1, wherein each of the plurality of optical patterns has an aspect ratio of 0.3 to 3.0.

9. The polarizing plate of claim 1, wherein the first resin layer has a self-adhesive property, and the first resin layer is directly formed on the polarizing film.

10. The polarizing plate of claim 1, wherein at least one of an adhesive layer, and a protective layer is further formed between the contrast enhancement layer and the polarizing film.

11. The polarizing plate of claim 1, wherein the high refractive index layer has a refractive index of 1.53 to 1.70.

12. The polarizing plate of claim 1, wherein the high refractive index layer is formed of a composition for the high refractive index layer comprising a high refractive index compound comprising at least one of a fluorene-based compound and a biphenyl-based compound, an ultraviolet curable compound, an initiator, and inorganic particles.

13. The polarizing plate of claim 12, wherein the inorganic particles comprise zirconia.

14. The polarizing plate of claim 12, wherein the composition for the high refractive index layer further comprises an antistatic agent.

15. The polarizing plate of claim 1, wherein a second base layer is further formed between the contrast enhancement layer and the anti-reflection film.

16. The polarizing plate of claim 15, wherein an adhesive layer is further formed between the contrast enhancement layer and the anti-reflection film.

17. The polarizing plate of claim 16, wherein the adhesive layer has a refractive index of 1.40 to 1.65.

18. The polarizing plate of claim 16, wherein the second base layer and the adhesive layer are sequentially formed between the contrast enhancement layer and the anti-reflection film,

the second substrate layer has an in-plane retardation, Re, of 8,000 nanometers or greater than 8,000 nanometers at a wavelength of 550 nanometers,

the adhesive layer has a refractive index of 1.40 to 1.65.

19. The polarizing plate of claim 18, wherein the first substrate layer has an in-plane retardation Re of 60 nm or less than 60 nm at a wavelength of 550 nm.

20. The polarizing plate of claim 1, wherein the first base layer is formed directly on the contrast enhancement layer, and wherein the first base layer has an in-plane retardation Re of 60 nanometers or less than 60 nanometers at a wavelength of 550 nanometers.

21. A liquid crystal display device comprising the polarizing plate according to any one of claims 1 to 20.

Technical Field

The present invention relates to a polarizing plate and a liquid crystal display device including the same.

Background

The liquid crystal display device operates by emitting light from a backlight unit through a liquid crystal panel. Therefore, the front Contrast (CR) in the liquid crystal display device is relatively good. However, the side contrast of the liquid crystal display device is relatively low. Therefore, it is required to minimize the reduction of the front contrast when increasing the side contrast to improve the visibility.

Meanwhile, the liquid crystal display device may not be continuously driven but may be in a non-driving state. When the liquid crystal display device is in a non-driving state, external light such as sunlight or lamp light may be irradiated on a screen of the liquid crystal display device. In this case, the screen may have unevenness or color difference, or the reflected light may be split, so that the black visual sensitivity and appearance of the liquid crystal display device may be deteriorated.

Therefore, the following polarizing plate is required: the polarizing plate has an improved front contrast ratio and an improved side contrast ratio in a driving state, and does not cause the above-described deterioration of black visual acuity and appearance in a non-driving state.

The background art is disclosed in Japanese patent laid-open publication No. 2006-251659.

Disclosure of Invention

Technical problem

The present invention provides a polarizing plate capable of improving black visual acuity and appearance even when external light such as sunlight or lamp light is irradiated.

The present invention provides a polarizing plate capable of preventing rainbow color difference or unevenness even when external light such as sunlight or lamp light is irradiated.

The invention provides a polarizing plate capable of improving visibility, side viewing angle and side contrast.

Technical solution

The polarizing plate of the present invention may include a polarizing film, a contrast enhancing layer, and an anti-reflection film laminated in order, the anti-reflection film having a minimum reflectance of 0.45% or less than 0.45%, the anti-reflection film including a first base layer, a high refractive index layer, and a low refractive index layer laminated in order on the contrast enhancing layer, the contrast enhancing layer including a first resin layer and a second resin layer facing the first resin layer, wherein the second resin layer includes a patterned portion including a plurality of optical patterns each having a base angle (θ) of 75 ° to 90 ° and a flat portion formed between the plurality of optical patterns, the patterned portion satisfying equation 1 below,

< equation 1>

1＜P/B≤6

(in equation 1, P is the pitch (unit: micrometer) of the patterned portion, and

b is the maximum width (unit: micrometer) of the flat portion,

the polarizing plate has a reflectance slope of 0.3 or less than 0.3 according to the following equation 2:

< equation 2>

Reflectivity slope R₆₀₀-R₅₀₀|/|600-500|×100

(in equation 2, R₆₀₀Is the reflectance value of the polarizing plate at a wavelength of 600 nm, and

R₅₀₀is the reflectance value of a polarizing plate at a wavelength of 500 nm)

The liquid crystal display device of the present invention may include the polarizing plate of the present invention.

Advantageous effects

The present invention provides a polarizing plate capable of improving black visual acuity and appearance even when external light such as sunlight or lamp light is irradiated.

The present invention provides a polarizing plate capable of preventing rainbow color difference or unevenness even when external light such as sunlight or lamp light is irradiated.

The invention provides a polarizing plate capable of improving visibility, side viewing angle and side contrast.

Drawings

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

Fig. 2 is a detailed sectional view of the contrast enhancement layer of the polarizing plate shown in fig. 1.

Fig. 3 is a cross-sectional view of a contrast enhancing layer of a polarizing plate according to another embodiment of the present invention.

Fig. 4 is a cross-sectional view of a polarizing plate according to still another embodiment of the present invention.

Fig. 5 is a cross-sectional view of a polarizing plate according to still another embodiment of the present invention.

Fig. 6 is a cross-sectional view of a polarizing plate according to still another embodiment of the present invention.

Fig. 7 shows the change in reflectance depending on the wavelength of the polarizing plates of examples 1 to 5.

Fig. 8 shows the change in reflectance depending on the wavelength of the polarizing plates of examples 6 to 10.

Detailed Description

Exemplary embodiments of the present invention are explained in detail with reference to the accompanying drawings. It is to be understood that the present invention is not limited to the following examples, but may be embodied in various forms. In the drawings, portions irrelevant to the present description are omitted for clarity. Throughout the specification, like components are denoted by like reference numerals.

Spatially relative terms such as "upper portion" and "lower portion" as used herein are defined with reference to the drawings. Thus, it should be understood that the term "upper portion" may be used interchangeably with the term "lower portion" and the term "lower portion" may be used interchangeably with the term "upper portion". It will be understood that when an element is referred to as being "on" another element, it can be directly on the other element, or intervening layers may be present. On the other hand, when an element is said to be "directly" placed on another element, then there is "no intermediate layer" between the two elements.

The terms "horizontal direction" and "vertical direction" used herein refer to the longitudinal direction and the lateral direction of the screen of the liquid crystal display, respectively.

As used herein, the term "lateral" refers to a spherical coordinate system (spherical coordinate system)A region where θ is in the range of 60 ° to 90 ° in the spherical coordinate system, with respect to the horizontal direction, is indicated by (0 ° ), the front face is indicated by (180 °,90 °), the left end point is indicated by (0 °,90 °), and the right end point is indicated by (0 °,90 °).

The term "top part" as used herein refers to a portion located at the uppermost portion with respect to the lowermost portion of the engraved optical pattern.

The term "aspect ratio" used herein refers to a ratio of the maximum height of the optical pattern to the maximum width of the optical pattern (maximum height/maximum width).

The term "pitch" as used herein refers to the sum of the maximum width of an optical pattern and the width of a flat portion adjacent to the optical pattern.

The term "in-plane retardation (Re)" as used herein is a value at a wavelength of 550 nm and is represented by the following equation a:

< equation A >

Re＝(nx-ny)×d

(in equation A, nx and ny are refractive indices in the slow axis direction and in the fast axis direction, respectively, at a wavelength of 550 nm in the corresponding protective layer or base layer, and d is the thickness (unit: nm) of the corresponding protective layer or base layer).

The term "minimum reflectance" of the antireflection film as used herein means that, for a sample prepared by laminating a black acrylic sheet (kyanots industries, ltd) on the first base layer of the antireflection film, the reflectance of the sample in SCI reflection mode (light source: D65 light source, light source aperture:

25.4 mm, measurement viewing angle: 2 deg.) measured at a wavelength in the range of 360 nm to 740 nm.

The term "light reflectance" of the polarizing plate as used herein means that, for a sample prepared by laminating a black acrylic sheet (crayon, manufactured by ritonashi industries, ltd.) on the lower portion of the polarizing film of the polarizer, the reflectance of the sample in SCI reflection mode (light source: D65 light source, light source aperture:

25.4 mm, measurement viewing angle: 2 °) Y (D65) measured at a wavelength in the range of 360 nm to 740 nm. Y (D65) is a Y value measured using a D65 light source, and may be an integrated value of reflectance at each wavelength × intensity of the light source at each wavelength × Y (green stimulus value) color function in a wavelength of a visible light region.

The term "reflectance slope" of the polarizing plate as used herein means that a sample prepared by laminating a black acrylic sheet (clarias) on a lower portion of a polarizing film of the polarizing plate is measured using a Spectrophotometer (Spectrophotometer, koch)Nicamidean limited, CM-3600A) in SCI reflection mode (light source: d65 light source, light source diameter:

25.4 mm, measurement viewing angle: 2 °) reflectance at a wavelength of 500 nm and a reflectance slope at a wavelength of 600 nm measured over a wavelength range of 360 nm to 740 nm, and the reflectance slope value is calculated according to the following equation 2:

< equation 2>

Reflectivity slope R₆₀₀-R₅₀₀|/|600-500|×100

(in equation 2, R₆₀₀Is the reflectance value of the polarizing plate at a wavelength of 600 nm, and

R₅₀₀is the reflectance value of a polarizing plate at a wavelength of 500 nm)

The term "reflectance value" means a value of% reflectance.

As used herein, "(meth) acrylic-based" means acrylic-based and/or methacrylic-based.

Hereinafter, a polarizing plate according to an embodiment of the present invention will be described with reference to fig. 1 and 2. Fig. 1 is a cross-sectional view of a polarizing plate according to an embodiment of the present invention. Fig. 2 is a detailed sectional view of the contrast enhancement layer of the polarizing plate shown in fig. 1.

Referring to fig. 1, a polarizing plate (10) may include a polarizing film (100), a contrast enhancing layer (200), and an anti-reflection film (300).

The polarizing plate (10) is used as a viewer-side polarizing plate in a liquid crystal display. Therefore, when the liquid crystal display device is not driven, the polarizing plate (10) can be affected by external light such as sunlight or lamp light. The polarizing plate (10) may include a polarizing film (100), a contrast enhancing layer (200), and an antireflection film (300) laminated in this order. The anti-reflective film (300) may have a minimum reflectance of 0.45% or less than 0.45%. The contrast enhancement layer (200) may include a first resin layer and a second resin layer described below. Therefore, when external light is incident on the polarizing plate (10) when the liquid crystal display device is not driven, the polarizing plate can prevent external light scattering or dispersion caused by the optical patterns in the first and second resin layers. Therefore, by preventing color difference, unevenness, or splitting of the screen, the appearance and black visual sensitivity can be improved during the non-driving state of the liquid crystal display device.

The polarizing plate may have a reflectance slope of 0.3 or less than 0.3, for example, 0.01 to 0.3. Within this range, even when external light is irradiated on the polarizing plate when the liquid crystal display device is not driven, dispersion of the external light caused by the optical pattern in the first resin layer or the second resin layer can be reduced to improve the appearance and black visual sensitivity of the liquid crystal display device. The reflectance slope is used to evaluate whether or not a color difference or a spot is visually recognized when an observer views a screen when the liquid crystal display device is not driven at wavelengths of 500 nm to 600 nm, and includes 550 nm, which is a representative wavelength of a visible light region. When the reflectance slope is 0.3 or less than 0.3, the black visual sensitivity is good, and the visibility can be improved upon driving. The above range of the reflectance slope can be achieved by the polarizing plate of the present invention.

In one embodiment, the polarizer may have a light reflectance (luminance reflectance) of 2% or less than 2%, for example, 0% to 2%, 0% to 1.5%. Within this range, even when external light is irradiated on the polarizing plate when the liquid crystal display device is not driven, dispersion of the external light caused by the optical pattern in the first resin layer or the second resin layer can be reduced to improve the appearance and black visual sensitivity of the liquid crystal display device. The light reflectance was used to evaluate the color difference or the absence of speckles when the liquid crystal display device was not driven, and the black visual sensitivity. The lower the light reflectance is, the better the black visual sensitivity is, and no color difference or mottle is displayed when the liquid crystal display device is not driven. The above range of light reflectance can be achieved by the polarizing plate of the present invention.

In addition, in the polarizing plate (10), a polarizing film (100) and a contrast enhancement layer (200) are laminated in order. Accordingly, visibility can be improved when driving the liquid crystal display device to improve side contrast and side viewing angle. Specifically, the anti-reflection film (300) formed on the contrast enhancement layer (200) can perform the above-described non-driving function and does not affect visibility or side contrast when the liquid crystal display device is driven.

Specifically, in the polarizing plate (10), the polarizing film (100), the contrast enhancement layer (200), and the antireflection film (300) are laminated, and the external damage due to external light can be prevented when the liquid crystal display device is not driven, and the visibility can be improved by the contrast enhancement layer (200) when the liquid crystal display device is driven. Therefore, the above-described improved effect can be obtained in both the driving state and the non-driving state.

Polarizing film

The polarizing film (100) can polarize and transmit light incident from the liquid crystal panel.

The polarizing film (100) may include a polarizer. Specifically, the polarizer may include a polyvinyl alcohol-based polarizer formed by uniaxially stretching a polyvinyl alcohol-based film, or a polyene-based polarizer formed by dehydrating a polyvinyl alcohol-based film. The polarizer may have a thickness of 5 to 40 micrometers. Within this range, the polarizer may be used in an optical display device.

The polarizing film (100) may include a polarizer and a protective layer formed on at least one surface of the polarizer. The protective layer can protect the polarizer to enhance the reliability and mechanical strength of the polarizer.

The protective layer may include at least one of an optically transparent protective film and a protective coating.

When the protective layer is a protective film type, the protective layer may include a protective film formed of an optically transparent resin. The protective film may be formed by melting and extruding a resin. If necessary, a stretching process may be added. The resin may be selected from the group consisting of: cellulose ester resins including triacetyl cellulose (TAC) and the like, cyclic polyolefin resins including amorphous Cyclic Olefin Polymers (COP), polycarbonate resins, polyester resins including polyethylene terephthalate (PET) and the like, polyether sulfone resins, polysulfone resins, polyamide resins, polyimide resins, acyclic polyolefin resins, polyacrylate resins including polymethyl methacrylate resins, polyvinyl alcohol resins, polyvinyl chloride resins, polyvinylidene chloride resins, and acrylic resins.

When the protective layer is a protective coating type, adhesion to a polarizer, transparency, mechanical strength, thermal stability, moisture barrier property, and durability can be improved. In one embodiment, the protective coating layer may be formed of an active energy ray-curable resin composition including an active energy ray-curable compound and a polymerization initiator.

The active energy ray-curable compound may include at least one of a cation-polymerizable curable compound, a radical-polymerizable curable compound, a urethane resin, and a silicone resin. The cationically polymerizable curable compound may be an epoxy-based compound having at least one epoxy group in the molecule, or an oxetane-based compound having at least one oxetane ring in the molecule. The radical polymerizable curable compound may be a (meth) acrylic compound having at least one (meth) acryloyloxy group in the molecule.

The epoxy compound may be at least one of a hydrogenated epoxy compound, a chain aliphatic epoxy compound, a cyclic aliphatic epoxy compound, and an aromatic epoxy compound.

The radically polymerizable curable compound can provide a protective coating having excellent hardness, mechanical strength, and durability. A radical polymerizable curable compound can be obtained by reacting two or more (meth) acrylate monomers having at least one (meth) acryloyloxy group in the molecule with a compound having such a functional group, and a (meth) acrylate oligomer having at least two (meth) acryloyloxy groups can be mentioned as an example. Examples of the (meth) acrylate monomer may include a monofunctional (meth) acrylate monomer having one (meth) acryloyloxy group in the molecule, a bifunctional (meth) acrylate monomer having two (meth) acryloyloxy groups in the molecule, and a multifunctional (meth) acrylate monomer having three or more (meth) acryloyloxy groups in the molecule. Examples of the (meth) acrylate oligomer may include urethane (meth) acrylate oligomer, polyester (meth) acrylate oligomer, epoxy (meth) acrylate oligomer, and the like.

The polymerization initiator can cure the active energy ray-curable compound. The polymerization initiator may include at least one of a photo-cationic initiator and a photo-sensitizer. Photocationic initiators known to those skilled in the art may be used. Specifically, an onium salt (onium salt) containing a cation and an anion can be used as the photo cation initiator. Specifically, examples of the cation may include diphenyliodonium, 4-methoxydiphenyliodonium, bis (4-methylphenyl) iodonium, bis (4-t-butylphenyl) iodonium, bis (dodecylphenyl) iodonium, such as (4-methylphenyl) [ (4- (2-methylpropyl) phenyl)]Diaryliodonium such as iodonium, triphenylsulfonium), triarylsulfonium such as diphenyl-4-thiophenoxyphenylsulfonium, bis [4- (diphenylthio) phenyl]Thioethers, and the like. Examples of the anion may include hexafluorophosphate (PF)₆ ^-) Tetrafluoroborate (BF)₄ ^-) Hexafluoroantimonate (SbF)₆ ^-) Hexafluoroarsenate (AsF)₆ ^-) Hexachloroantimonate (SbCl)₆ ^-) And the like. Photosensitizers conventionally known to those skilled in the art may be used. Specifically, the photosensitizer may be at least one selected from the group consisting of thioxanthone, phosphorus, triazine, acetophenone, benzophenone, benzoin, and oxime.

The active energy ray-curable resin composition may further contain conventional additives such as a silicon leveling agent, an ultraviolet absorber, an antistatic agent, and the like.

The protective layer may have a thickness of 5 to 200 micrometers, specifically 30 to 120 micrometers. When the protective layer is a protective film type, the protective layer may have a thickness of 30 to 100 micrometers. When the protective layer is a protective coating film type, the protective layer may have a thickness of 5 to 50 micrometers. Within this range, the protective layer may be used in a display device.

Functional coatings such as a primer layer, a hard coat layer, an anti-fingerprint layer, an anti-reflection layer, etc. may be further formed on at least one surface of the protective layer. The primer layer may improve adhesion between the polarizer and the protective layer. Hard coatings, anti-fingerprint layers, anti-reflection layers, etc. may provide other functions to protective layers, polarizing films, etc.

When the protective layer is of a protective coating film type, the protective layer may be formed directly on the polarizer. However, when the protective layer is of a protective film type, the protective film may be formed on the polarizer by an adhesive for the polarizer, such as an adhesive layer formed of an aqueous adhesive, a photocurable adhesive, or a pressure-sensitive adhesive.

Contrast enhancement layer

The contrast enhancement layer (200) may be formed on a light exit surface of the polarizing film (100) to diffuse polarized light transmitted from the polarizing film (100) to improve visibility.

Referring to fig. 1 and 2, the contrast enhancement layer 200 may include a first resin layer 210 and a second resin layer 220. The first resin layer (210) and the second resin layer (220) may face each other. Referring to fig. 1, a first resin layer (210) and a second resin layer (220) are sequentially formed on a polarizing film (100).

The second resin layer (220) may include a patterned portion having optical patterns (221), the patterned portion including the optical patterns (221) and a flat portion (222) formed between the optical patterns (221). Fig. 2 shows that each optical pattern (221) is an engraved pattern.

The patterned portion may satisfy the following equation 1 and each optical pattern (221) may have a base angle (θ) of 75 ° to 90 °. The base angle (θ) may mean that an angle between the inclined surface (223) of the optical pattern (221) and a line extending along the maximum width (W) of the optical pattern (221) is in a range of 75 ° to 90 °. In measuring the base angle (θ), the inclined surface is defined as an inclined surface directly connected to the flat portion. Within this range, the relative front luminance can be increased while the front contrast and the side contrast are simultaneously improved. In addition, the difference between the front contrast and the side contrast can be reduced, and the contrast at the same side viewing angle and the contrast at the same front viewing angle can be increased. In addition, it is more advantageous to secure the above reflectance slope by satisfying the above equation 1 and having the base angle (θ) of 75 ° to 90 °. Specifically, the base angle (θ) may range from 80 ° to 90 °, 85 ° to 90 °. P/B (ratio of P to B) may range from 1.5 to 3:

< equation 1>

1＜P/B≤6

(in equation 1, P is the pitch (unit: micrometer) of the patterned portion, and

b is the maximum width (unit: micrometer) of the flat portion)

Fig. 2 shows that the two base angles of each optical pattern are the same, but optical patterns having different base angles may be included in the scope of the present invention as long as the base angles are within the above-described range of 75 ° to 90 °.

The optical pattern (221) may be an engraved optical pattern comprising a first surface (224) at the top and at least one inclined surface (223) connected to the first surface (224).

In the optical display device, the first surface (224) may be formed at the top, so that light reaching the second resin layer (220) is diffused by the first surface (224) to a greater extent, thereby increasing a viewing angle and brightness. Accordingly, the polarizing plate can increase light diffusion and minimize a loss of brightness.

Fig. 2 shows that the first surface (224) is flat and is formed parallel to the flat portion (222). However, the first surface (224) may have a small relief surface, or may be a curved surface. When the first surface (224) is a curved surface, a lenticular lens pattern may be formed on the first surface.

The width (a) of the first surface (224) may be 0.5 to 30 micrometers, specifically 2 to 20 micrometers. Fig. 2 shows that the engraved pattern has a trapezoidal cross-sectional shape in which one flat surface is formed at the uppermost surface thereof and the inclined surface is the flat surface (for example, a truncated prism pattern having a truncated triangular cross-section, i.e., a truncated prism shape). However, as shown in fig. 3, an engraved pattern in which the first surface is formed at the uppermost surface thereof and the inclined surface is a curved surface, such as a contrast enhancement layer (200B) having a truncated lenticular pattern or a truncated microlens pattern, may also be included within the scope of the present invention. In some embodiments, the engraved pattern may have a trapezoidal shaped cross section, a rectangular shaped cross section, or a square shaped cross section with good reflectivity slope and good visibility.

The optical pattern (221) may have an aspect ratio (H/W) of 0.3 to 3.0, specifically 0.4 to 2.5, more specifically 0.4 to 1.5, 0.4 to 1.0. Within this range, the side contrast and side viewing angle of the optical display device can be improved.

The optical pattern (221) may have a height (H) of 40 microns or less than 40 microns, specifically 30 microns or less than 30 microns, more specifically 3 to 15 microns. Within this range, the contrast, viewing angle and brightness can be improved without showing moire phenomenon. Fig. 2 shows that the optical patterns of the patterned portions have the same height. However, the heights of the optical patterns may be different from each other, or at least one of the heights of adjacent optical patterns may be different from each other.

The optical pattern (221) may have a maximum width (W) of 50 micrometers or less than 50 micrometers, specifically 20 micrometers or less than 20 micrometers, more specifically 3 micrometers to 20 micrometers, 5 micrometers to 30 micrometers. Within this range, the contrast, viewing angle and brightness can be improved without showing moire phenomenon. Fig. 2 shows that the optical patterns of the patterned portions have the same maximum width. However, the maximum widths of the optical patterns may be different from each other, or at least one width of adjacent optical patterns may be different from each other.

The flat portion (222) can emit light that reaches the flat portion and can diffuse the light to maintain front contrast and brightness.

The ratio (W/B) of the maximum width (W) of the optical pattern (221) to the width (B) of the flat portion (222) may be 5 or less than 5, specifically 0.1 to 3, more specifically 0.15 to 2. Within this range, while the contrast at the same side viewing angle and the same front viewing angle is enhanced and the moire phenomenon is suppressed, the relative front luminance can be enhanced, and the difference between the front contrast and the side contrast can be reduced. The width (B) of the flat portion (222) may be about 1 micron to about 300 microns, specifically 3 microns to 50 microns. Within this range, the front luminance can be enhanced.

The maximum width (W) of one optical pattern (221) and the adjacent flat portion (222) may form one pitch (P).

The pitch (P) may range from about 5 microns to about 500 microns, specifically from about 10 microns to about 50 microns. Within this range, the brightness and contrast can be enhanced while the moire phenomenon is suppressed. Fig. 2 shows that the patterned portions have the same pitch as the adjacent patterned portions. However, the pitches may be different from each other, or at least one pitch of adjacent patterned portions may be different from each other.

Fig. 2 shows that the optical pattern is an engraved pattern. However, the optical pattern may be an embossed pattern. In addition, fig. 2 shows that the optical pattern is formed in an extended form of a stripe shape (stripe), but the optical pattern may be formed in a dot shape. The term "dots" as used herein means that the combination of fill pattern and optical pattern is dispersed. In some embodiments, the optical pattern may be an engraved pattern formed in an extended form of a stripe shape.

The refractive index of the second resin layer (220) may be higher than that of the first resin layer (210). The second resin layer (220) may include patterned portions on a surface facing the first resin layer (210), the patterned portions including optical patterns (221) and flat portions (222) formed between the optical patterns (221). The optical pattern (221) may include an inclined surface (223). Accordingly, the contrast enhancement layer (200) can diffuse polarized light incident from the polarizing film (100) and emit the polarized light to increase relative front luminance while simultaneously improving front and side Contrast (CR). In addition, a reduction in front contrast can be minimized although side contrast is increased, and a difference between the front contrast and the side contrast can be reduced while increasing the contrast at the same side viewing angle and the contrast at the same front viewing angle.

The second resin layer (220) may be formed on the first resin layer (210), and may diffuse light reaching the first resin layer (210) to increase light diffusion.

The refractive index of the second resin layer (220) may be higher than that of the first resin layer (210). The absolute value of the difference in refractive index between the second resin layer and the first resin layer (refractive index of the second resin layer — refractive index of the first resin layer) may be 0.05 to 0.20, more specifically 0.06 to 0.15. In this range, the diffusion and contrast of the collected light can be increased. In particular, the contrast enhancement layer having the refractive index difference of 0.06 to 0.12 may show an excellent diffusion effect on polarized light in the optical display device, and may increase luminance at the same viewing angle. The second resin layer (220) may have a refractive index of 1.50 or more than 1.50, specifically 1.50 to 1.70, 1.50 to 1.60. Within this range, the light diffusion effect may be excellent. The second resin layer (220) may be formed of a UV curable composition or a heat curable composition including at least one of a (meth) acrylic resin, a polycarbonate-based resin, a silicone-based resin, and an epoxy-based resin, but is not limited thereto.

The first resin layer (210) can diffuse light by refracting and emitting light incident from the lower surface of the optical display device in various directions depending on an incident position. The first resin layer (210) may be formed to directly contact the second resin layer (220).

The first resin layer (210) may include a filling pattern (211) filling at least a portion of the optical pattern (221). The term "filling at least a portion" as used herein includes both structures in which the fill pattern completely fills the optical pattern and structures in which the fill pattern partially fills the optical pattern. In the structure in which the filling pattern partially fills the optical pattern, the remaining portion or the unfilled portion of the optical pattern may be filled with air or a resin having a predetermined refractive index. Specifically, the refractive index of the resin may be equal to or higher than that of the first resin layer and equal to or lower than that of the second resin layer.

The first resin layer (210) may have a refractive index of less than 1.52, specifically at least 1.35 and less than 1.50. Within this range, the first resin layer may have an excellent light diffusion effect, and may be easily prepared. The first resin layer (210) may be formed of a composition including a UV curable resin or a thermal curable resin including a transparent resin. For example, the resin may include at least one of a (meth) acrylic resin, a polycarbonate-based resin, a silicone-based resin, and an epoxy-based resin, but is not limited thereto. The transparent resin may have a transmittance of about 90% or greater than 90% when measured after being cured.

The contrast enhancement layer (200) may be laminated on the polarizing film (100).

In one embodiment, the first resin layer may be non-adhesive. In this case, at least one of an adhesive layer, or an adhesive/adhesive layer may be formed between the first resin layer (210) and the polarizing film (100). In another embodiment, the first resin layer may have self-adhesive properties. In this case, the first resin layer (210) may be directly formed on the polarizing film (100). When the first resin layer has a self-adhesive property, the first resin layer may be formed of an adhesive resin including at least one of an acrylic resin, an epoxy resin, and a urethane resin. The first resin layer may further include at least one of a curing agent, a silane coupling agent, and an additive in the binder resin.

At least one of an adhesive layer, an adhesive/bonding layer, and the above protective film may be further formed between the contrast enhancement layer (200) and the polarizing film (100).

The contrast enhancement layer (200) may have a thickness of 10 to 100 micrometers, specifically 20 to 60 micrometers, more specifically 20 to 45 micrometers. Within this range, the contrast enhancement layer may be used in an optical display device.

Anti-reflection film

The antireflection film (300) is formed on the contrast enhancement layer (200).

The anti-reflective film (300) may have a minimum reflectance of 0.45% or less than 0.45%. Within this range, external light can be prevented from being dispersed through the optical pattern in the contrast enhancing layer, and the appearance can be improved. In some embodiments, the antireflective film may have a minimum reflectance of 0% to 0.45%, 0.01% to 0.45%.

The anti-reflective film (300) may include a first substrate layer (310) and a laminate (320) of a high refractive index layer and a low refractive index layer.

The anti-reflection film (300) may be laminated on the contrast enhancement layer (200) in the order of the first base layer (310), the high refractive index layer, and the low refractive index layer. The low refractive index layer of the antireflective film (300) may have a pencil hardness of 2H or greater than 2H, e.g., 2H to 3H. Within this range, the antireflection film may be used to protect the polarizing film at the outermost surface of the polarizing plate.

The anti-reflective film (300) may have a thickness of 20 to 150 microns, such as 40 to 100 microns. Within this range, the antireflection film can be used for the polarizing plate.

The first substrate layer (310) may support the anti-reflection film and increase the mechanical strength of the anti-reflection film.

The first substrate layer (310) may have a refractive index of 1.40 to 1.80, e.g. 1.45 to 1.70, 1.48 to 1.50, 1.50 to 1.60. Within this range, when the high refractive index layer and the low refractive index layer are sequentially laminated, the minimum reflectance of the anti-reflection film can be reduced.

The first substrate layer (310) may be formed of an optically transparent resin. Specifically, the resin may include at least one of: cellulose ester resins including triacetyl cellulose (TAC) and the like; polyester resins including polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, and the like; a polycarbonate resin; poly (meth) acrylate resins including polymethyl methacrylate and the like; a polystyrene resin; a polyamide resin; and a polyimide resin. In some embodiments, the resin may include a cellulose resin including triacetyl cellulose or the like, a polyester resin including polyethylene terephthalate, or the like.

The first substrate layer (310) may be an unstretched film, but the first substrate layer may be stretched by a predetermined method to become a retardation film or an isotropic optical film having a predetermined retardation range.

In one embodiment, the first substrate layer may have an in-plane retardation Re of 8,000 nanometers or greater than 8,000 nanometers, specifically 10,000 nanometers or greater than 10,000 nanometers, more specifically 10,100 nanometers to 15,000 nanometers. In this range, the rainbow spots may become invisible, and the light diffused through the contrast enhancement layer may be further diffused.

In another embodiment, the first substrate layer may be an isotropic optical film having an in-plane retardation Re of 60 nanometers or less than 60 nanometers, specifically 0 to 60 nanometers, more specifically 40 to 60 nanometers. Within this range, the viewing angle can be compensated to improve image quality. The term "isotropic optical film" used herein refers to a film having substantially the same nx, ny, and nz, and the term "substantially the same" includes not only the case of being completely the same but also the case including some errors.

In some embodiments, the first substrate layer may be an isotropic optical film having an in-plane retardation Re of 60 nanometers or less than 60 nanometers, specifically 0 to 60 nanometers, more specifically 40 to 60 nanometers. At this time, the first base layer may be directly formed on the contrast enhancing layer.

The first substrate layer (310) may have a light transmittance of 80% or more than 80%, specifically 85% to 95%, in the visible light region. Within this range, the first base layer may be used for the polarizing plate.

The first base layer (310) may include a base film and a primer layer formed on at least one surface of the base film. The ratio of the refractive index of the primer layer to the refractive index of the base film (refractive index of the primer layer/refractive index of the base film) is 1.0 or less than 1.0, specifically 0.6 to 1.0, more specifically 0.69 to 0.95, more specifically 0.7 to 0.9, more specifically 0.72 to 0.88. Within this range, the transmittance of the first base layer may be increased. The base film may have a refractive index of 1.3 to 1.7, specifically 1.4 to 1.6. Within this range, the base film may be used as the base film of the first base layer, and the refractive index with respect to the primer layer may be easily controlled while increasing the transmittance of the first base layer. The base film may include a film formed of the above-described resin. The primer layer may have a refractive index of 1.0 to 1.6, specifically 1.1 to 1.6, more specifically 1.1 to 1.5. Within this range, the transmittance of the base layer can be increased by having an appropriate refractive index with respect to the base film. The primer layer can have a thickness of 1 to 200 nanometers, specifically 60 to 200 nanometers. In this range, the primer film may be used for the optical film, and has an appropriate refractive index with respect to the base film to increase the transmittance of the base layer and prevent a brittle phenomenon. The primer layer may be a non-urethane primer layer that does not contain urethane groups. Specifically, the primer layer may be formed of a composition for the primer layer including a monomer or a resin such as polyester, acryl, or the like. The above refractive index range can be provided by controlling the mixing ratio (e.g., molar ratio) of the monomers. The composition for the primer layer may further include at least one additive such as a UV absorber, an antistatic agent, an antifoaming agent, a surfactant, and the like.

The first substrate layer (310) may have a thickness of 10 to 150 microns, specifically 30 to 100 microns, more specifically 40 to 90 microns. Within this range, the first base layer may be used in the antireflection film.

The high refractive index layer may be formed on the first substrate layer together with the low refractive index layer to increase the hardness of the anti-reflection film and reduce the minimum reflectance of the anti-reflection film. The high refractive index layer may be a single layer, or two or more high refractive index layers having different refractive indices may be laminated.

The high refractive index layer may have a refractive index higher than that of the low refractive index layer. The high refractive index layer may have a refractive index of 1.53 to 1.70, for example 1.56 to 1.65. Within this range, when the low refractive index layer is laminated on the high refractive index layer, the minimum reflectance of the anti-reflection film can be reduced.

The high refractive index layer can have a thickness of 1 to 50 microns, specifically 1 to 30 microns, more specifically 5 to 10 microns. In this range, the high refractive index layer can be used for the antireflection film, and the hardness can be ensured.

The high refractive index layer may be formed of a composition for the high refractive index layer that may provide a refractive index of 1.53 to 1.70 after curing. The composition for the high refractive index layer may have a refractive index of 1.53 to 1.70, for example, 1.55 to 1.65.

In one embodiment, the composition for the high refractive index layer may include a high refractive index compound having a refractive index of 1.6 or more than 1.6, specifically 1.615 to 1.635, more specifically 1.62 to 1.63, a UV curable compound having a refractive index lower than that of the high refractive index compound, an initiator, and inorganic particles.

The high refractive index compound may be a UV curable compound, and may include at least one of: high refractive index monomer or high refractive index resin, such as fluorene-based compound, biphenyl-based compound, bisphenol-based compound, thiophenyl ether-based compound and thionaphthalene-based compound. In some embodiments, by using at least one of fluorene-based compounds and biphenyl-based compounds as the high refractive index compound, the refractive index of the high refractive index layer can be increased to further reduce the minimum reflectance of the antireflection film.

The fluorene-based compound may be a resin represented by the following formula 1, but is not limited thereto.

< formula 1>

(in the formula 1, m and n are each 1 or an integer greater than 1, m + n is an integer of 2 to 8, and R is hydrogen or methyl). In some embodiments, m + n may be an integer of 4. In this case, the refractive index and hardness of the cured product may be increased when used together with the UV curable compound, and the minimum reflectance may be reduced to 0.45% or less than 0.45% when a low refractive index layer described below is laminated on a high refractive index layer.

The high refractive index monomer may have a refractive index higher than that of the UV curable compound, and the high refractive index monomer may have a viscosity lower than that of the high refractive index resin, so that the applicability of the composition for the high refractive index layer may be improved.

The high refractive index monomer may have a refractive index of 1.55 or greater than 1.55, specifically 1.56 to 1.59, more specifically 1.57 to 1.58. Within this range, the refractive index of the cured product may be increased to reduce the minimum reflectance of the anti-reflective film. In one embodiment, the high refractive index monomer may include a compound represented by the following formula 2. The high refractive index monomer may be synthesized using a commercially available product or by a conventional method:

< formula 2>

(in the formula 2, n is an integer of 1 to 4, and R is hydrogen or methyl).

The high refractive index compound may be present in the composition for the high refractive index layer in an amount of 5 to 60% by weight, for example, 10 to 45% by weight, based on the solid content. Within this range, the minimum reflectance may be sufficiently reduced when the low refractive index layer is laminated on the high refractive index layer, and the hardness of the anti-reflection film may be sufficiently increased. The term "solid content" as used herein means the entire composition except for the solvent, and is not limited to only liquid or solid phase.

The refractive index of the UV curable compound may be lower than that of the high refractive index compound. However, the UV curable compound may form a matrix of the high refractive index layer and increase the hardness of the high refractive index layer. The composition including only the high refractive index compound may reduce the hardness of the anti-reflection film, and may not be used in an optical display device. In some embodiments, the UV curable compound may have a UV curable group such as a (meth) acrylate group or an epoxy group. The UV curable compound may include at least one of a difunctional or higher multifunctional (meth) acrylate monomer, an oligomer formed from the foregoing monomer, and a resin formed from the foregoing monomer. For example, the UV curable compound may be a difunctional to 10 functional (meth) acrylate compound.

The UV curable compound may include at least one of: for example, polyfunctional (meth) acrylates such as esters of polyols and (meth) acrylic acids, or polyfunctional urethane (meth) acrylates synthesized from polyols, isocyanate compounds, or hydroxy esters of (meth) acrylic acids.

The UV curable compound may include a difunctional (meth) acrylate compound or a higher functional (meth) acrylate compound. Examples of the bifunctional (meth) acrylate compound may include di (meth) acrylates such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di (meth) acrylate, nonanediol di (meth) acrylate, ethoxylated hexanediol di (meth) acrylate, propoxylated hexanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, ethoxylated neopentyl glycol di (meth) acrylate, and hydroxypivalic acid neopentyl glycol di (meth) acrylate. Examples of the trifunctional or higher-functional (meth) acrylate compound may include tri (meth) acrylates such as trimethylolpropane tri (meth) acrylate, ethoxylated trimethylolpropane tri (meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, tris 2-hydroxyethyl isocyanurate tri (meth) acrylate, and glycerol tri (meth) acrylate; trifunctional (meth) acrylate compounds such as pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate and ditrimethylolpropane tri (meth) acrylate; a polyfunctional (meth) acrylate compound having three or more functional groups, such as pentaerythritol tetra (meth) acrylate, di-trimethylolpropane tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, di-trimethylolpropane penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ditrimethylolpropane hexa (meth) acrylate, or a polyfunctional (meth) acrylate compound in which a part of the (meth) acrylate is substituted with an alkyl group or epsilon-caprolactone.

The UV curable compound may be present in the composition for the high refractive index layer in an amount of 20 to 60% by weight on a solid content basis. In this range, the matrix of the high refractive index layer may have high hardness. In some embodiments, the UV curable compound may be present in an amount of 35 to 60 wt%, 35 to 50 wt%. Within this range, the minimum reflectance may be sufficiently reduced when the low refractive index layer is laminated on the high refractive index layer, and the hardness of the anti-reflection film may be sufficiently increased.

The initiator may cure the high refractive index compound and the UV curable compound to form the high refractive index layer. The initiator may include at least one of a conventional photo radical initiator and a photo cation initiator known to those skilled in the art. Although not particularly limited, the use of the initiator having an absorption wavelength of 400 nm or less enables the production of a high refractive index layer by mere photocuring.

The photo-radical initiator can generate radicals by light irradiation to catalyze the curing process. Examples of the photo radical initiator may include at least one of phosphorus, triazine, acetophenone, benzophenone, thioxanthone, benzoin, oxime, and phenyl ketone. The photo-cationic initiator may comprise salts of cations and anions. Examples of the cation may include diaryliodonium such as diphenyliodonium, 4-methoxydiphenyliodonium, bis (4-methylphenyl) iodonium, (4-methylphenyl) [4- (2-methylpropyl) phenyl ] iodonium]Iodonium, bis (4-tert-butylphenyl) iodonium, bis (dodecylphenyl) iodonium; triarylsulfonium such as triphenylsulfonium and diphenyl-4-thiophenoxyphenylsulfonium; bis [4- (diphenylsulfonium) phenyl]A thioether; bis [4- (bis (4- (2-hydroxyethyl) phenyl) sulfonium) phenyl]A thioether; (. eta.5-2, 4-cyclopentadien-1-yl) [ (1,2,3,4,5, 6-. eta.) - (1-methylethyl) benzene]Iron (1+), and the like. Examples of the anion may include tetrafluoroborate (BF)₄ ^-) Hexafluorophosphate radical (PF)₆ ^-) Hexafluoroantimonate (SbF)₆ ^-) Hexafluoroarsenate (AsF)₆ ^-) Hexachloroantimonate (SbCl)₆ ^-) And the like.

The initiator may be present in the composition for the high refractive index layer in an amount of 2 to 5% by weight, for example 2 to 4% by weight, based on the solid content. Within this range, the composition may be sufficiently cured, and the transmittance of the anti-reflective film may be prevented from being reduced by the residual amount of the initiator.

The inorganic particles may increase the refractive index and hardness of the high refractive index layer. The surface of the inorganic particles may be untreated or treated (e.g., with (meth) acrylate groups) to improve compatibility with other components in the composition and further increase the hardness of the high refractive index layer. The surface treatment may be performed on 5% to 50% of the total surface area of the inorganic particles. Within this range, the hardness can be increased by combining with a UV curable compound and a high refractive index resin. The inorganic particles may include at least one of silica, zirconia, titania, and alumina, and zirconia may be used in one embodiment. The inorganic particles may have an average particle diameter (D50) of 1 nm to 50 nm, specifically 5 nm to 20 nm. Within this range, the anti-reflection film may have increased hardness without deteriorating optical properties.

The inorganic particles may be present in the composition for the high refractive index layer in an amount of 2 to 35% by weight, for example, 5 to 30% by weight, on a solid content basis. Within this range, the anti-reflection film may have increased hardness without deteriorating optical properties.

The composition for the high refractive index layer may further include an antistatic agent.

The antistatic agent can reduce the surface resistance of the antireflection film. In one embodiment, the low refractive index layer of the anti-reflective film may have a refractive index of 9 × 10¹⁰Ohm/□ or less than 9 x 10¹⁰Ohm/□, e.g. 1X 10¹⁰Ohm/□ or less than 1X 10¹⁰Ohm/□ surface resistance.

The antistatic agent may include conventional antistatic agents known to those skilled in the art. For example, the antistatic agent may comprise a material having a quaternary ammonium cation and an anion. Examples of the anion may include halide, HSO₄ ^-、SO₄ ^2-、NO₃ ^-、PO₄ ^3-And the like. The antistatic agent may include a quaternary ammonium cation, but may also include an acrylic material containing a quaternary ammonium cation as a functional group in the molecule.

The antistatic agent may be present in the composition for the high refractive index layer in an amount of 2 to 10% by weight, for example, 3 to 7% by weight, based on the solid content. Within this range, an antistatic effect may be obtained without affecting the hardness of the anti-reflection film, and deterioration of properties such as hardness deterioration may be prevented while preventing migration (migration) of the antistatic agent.

The composition for the high refractive index layer may further include conventional additives known to those skilled in the art. For example, a defoaming agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a leveling agent, etc., may be included, but not limited thereto. The composition for the high refractive index layer may further include a solvent to improve coating properties of the composition for the high refractive index layer. The solvent may include at least one of propylene glycol monomethyl ether and methyl ethyl ketone.

The low refractive index layer may be formed on the high refractive index layer and has a refractive index lower than that of the high refractive index layer, so that the minimum reflectance of the anti-reflection film may be reduced. The difference in refractive index between the high refractive index layer and the low refractive index layer (refractive index of the high refractive index layer-refractive index of the low refractive index layer) may be 0.26 or more than 0.26, for example, 0.26 to 0.30. Within this range, the refractive index of the anti-reflection film can be reduced, and optical characteristics such as haze can be improved. The low refractive index layer may have a refractive index of 1.35 or less than 1.35, for example 1.25 to 1.32.

The low refractive index layer may have a thickness of 50 to 300 nanometers, such as 80 to 200 nanometers, specifically 80 to 150 nanometers. Within this range, the low refractive index layer may be used in the antireflection film.

The low refractive index layer may be formed of a composition for the low refractive index layer. The composition for the low refractive index layer may include inorganic particles, fluorine-containing monomers or oligomers thereof, non-fluorine-containing monomers or oligomers thereof, an initiator, and a fluorine-containing additive.

The inorganic particles may have a hollow structure and a low refractive index to lower the refractive index of the low refractive index layer. The inorganic particles may have a refractive index of 1.4 or less than 1.4, for example 1.2 to 1.38. The inorganic particles may comprise hollow silica. The inorganic particles may include untreated hollow particles, or the surface of the inorganic particles may be treated with UV curable functional groups. The inorganic particles have an average particle diameter (D50) equal to or less than the thickness of the low refractive index layer. The inorganic particles may have an average particle diameter of 30 nm to 150 nm, for example, 50 nm to 100 nm. Within this range, the inorganic particles may be included in the low refractive index layer, and optical properties such as haze and transmittance may be improved.

The fluorine-containing monomer or oligomer thereof together with the inorganic particles can lower the refractive index of the low refractive index layer, and together with the fluorine-free monomer or oligomer thereof, forms a matrix of the low refractive index layer. The fluorine-containing monomer may include a fluorine-containing (meth) acrylate-based compound. The fluorine-containing monomer may include conventional compounds known to those skilled in the art.

The non-fluorine-containing monomer or oligomer thereof may form a matrix of the low refractive index layer, and may include a UV curable compound. The non-fluorine containing monomer or oligomer thereof may be a difunctional or higher functional, e.g., difunctional to 10 functional (meth) acrylate compound. Specifically, the fluorine-free monomer may include the above-mentioned polyfunctional (meth) acrylate, such as polyol and ester of (meth) acrylic acid.

The same or different initiator as described in the composition for the high refractive index layer may be used.

The additives may add anti-contamination properties and thinning properties to the low refractive index layer, and conventional additives known to those skilled in the art may be used. The additive may include at least one of a fluorine-containing additive and a silicon-based additive. The fluorine-containing additive may be a UV curable fluorinated acrylic compound. For example, the KY-1200 series (shin-Etsu chemical) including KY-1203 may be used.

The composition for the low refractive index layer may include 20 to 70% by weight of inorganic particles, 10 to 50% by weight of fluorine-containing monomer or oligomer thereof, 5 to 25% by weight of non-fluorine-containing monomer or oligomer thereof, 2 to 5% by weight of initiator, and 1 to 10% by weight of additive, on a solid content basis. Within this range, pencil hardness of 2H or more than 2H and anti-fingerprint effect can be provided. In some embodiments, the composition for the low refractive index layer may include, on a solid content basis, 40 to 60% by weight of the inorganic particles, 20 to 40% by weight of the fluorine-containing monomer or oligomer thereof, 5 to 15% by weight of the non-fluorine-containing monomer or oligomer thereof, 2 to 4% by weight of the initiator, and 2 to 7% by weight of the additive.

The composition for the low refractive index layer may further comprise conventional additives known to those skilled in the art. For example, a defoaming agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a leveling agent, etc., may be included, but not limited thereto.

The composition for the low refractive index layer may further include a solvent to improve coating properties. The solvent may include at least one of methyl ethyl ketone, methyl isobutyl ketone, and ethylene glycol dimethyl ether.

The anti-reflective film (300) may be formed directly on the contrast enhancement layer (200). In other words, the patterned portion is formed after coating the composition for the second resin layer onto the first base layer (310) of the anti-reflection film (300), and the patterned portion is filled with the composition for the first resin layer, so that the second resin layer of the contrast enhancing layer is directly formed on the first base layer (310) of the anti-reflection film. Alternatively, the second resin layer may have self-adhesive properties, and the anti-reflective film (300) may be attached to the contrast enhancement layer (200). Alternatively, an adhesive layer, or an adhesive/adhesive layer may be interposed between the antireflection film (300) and the contrast enhancement layer (200).

Hereinafter, a polarizing plate according to another embodiment of the present invention will be described with reference to fig. 4.

Referring to fig. 4, a polarizing plate (20) is substantially the same as the polarizing plate (10) according to the embodiment of the present invention, except that a second base layer (400) and an adhesive layer (500) are further laminated between a contrast enhancing layer (200) and an anti-reflection film (300). Referring to fig. 4, the contrast enhancement layer (200), the second base layer (400), the adhesive layer (500), and the anti-reflection film (300) are laminated on the polarizing film (100) in this order.

The second substrate layer (400) may be formed between the contrast enhancement layer (200) and the anti-reflection film (300) to increase the mechanical strength of the polarizing plate. In addition, when the first base layer (310) of the anti-reflection film is an unstretched film or an isotropic optical film, other functions can be provided to the polarizing plate by using the retardation film as the second base layer.

The second substrate layer (400) may be formed of the same or different resin as the first substrate layer. The second substrate layer (400) may have a thickness that is the same as or different from the thickness of the first substrate layer described above. The second substrate layer (400) may have the same or different retardation as the retardation of the first substrate layer described above. In some embodiments, the second substrate layer may have an in-plane retardation Re of 8,000 nanometers or greater than 8,000 nanometers, specifically 10,000 nanometers or greater than 10,000 nanometers, more specifically from 10,100 nanometers to 15,000 nanometers.

The second substrate layer (400) may be formed directly on the contrast enhancement layer (200). Furthermore, although not shown in fig. 4, the second substrate layer (400) may be formed on the contrast enhancement layer (200) with an adhesive/bonding layer interposed therebetween.

The adhesive layer (500) may bond the second substrate layer (400) to the anti-reflective film (300).

The adhesive layer (500) may be formed of a composition for an adhesive layer including an adhesive resin and a curing agent. The adhesive resin may include at least one of a (meth) acrylic adhesive resin, an epoxy adhesive resin, a silicone adhesive resin, and a urethane adhesive resin. The curing agent may include conventional curing agents known to those skilled in the art. For example, the curing agent may include at least one of: isocyanate curing agents, epoxy curing agents, melamine curing agents, aziridine curing agents and amine curing agents. The composition for an adhesive layer may include at least one of a silane coupling agent, a crosslinking agent, and various additives.

The adhesive layer (500) may further include a light scattering agent. The light scattering agent may scatter external light incident on the polarizing plate to improve black visual acuity of a screen of the display device during non-driving. The light scattering agent may be spherical particles having an average particle size of 0.5 to 50 microns, for example 1 to 10 microns. The light scattering agent may include at least one of an inorganic light scattering agent, an organic light scattering agent, or an organic-inorganic hybrid light scattering agent. The inorganic light scattering agent, the organic light scattering agent, and the organic-inorganic hybrid type light scattering agent may include conventional light scattering agents known to those skilled in the art. In some embodiments, the light scattering agent may comprise an organic light scattering agent. Specifically, the light scattering agent may include at least one of: organic particles such as (meth) acrylic polymer resins, urethane polymer resins, epoxy polymer resins, vinyl polymer resins, polyester polymer resins, polyamide polymer resins, polystyrene polymer resins, or silicone polymer resins; and inorganic particles such as titanium oxide, zirconium oxide, and the like.

The adhesive layer (500) may have a refractive index of 1.40 to 1.65. Within this range, optical loss due to the adhesive layer may be minimized and light reflectance may be reduced by the reflectance reduction effect.

The adhesive layer (500) may have a thickness of 1 to 50 microns, for example 5 to 20 microns. In this range, the adhesive layer may be used in the polarizing plate, and the second base layer and the anti-reflection film may be well adhered.

The adhesive layer (500) may have a haze of 40% or less than 40%, for example 1% to 40%. Within this range, when the optical display device is not driven, the appearance of the optical display device may be improved, and the side contrast may not be reduced by the contrast enhancement layer during driving of the optical display device.

In some embodiments, a laminate of a second substrate layer having an in-plane retardation Re of 8,000 nm or more and an adhesive layer having a refractive index of 1.40 to 1.65 may be included between the contrast enhancement layer and the anti-reflection film to ensure a reflectance slope of 0.3 or less and improve visibility.

Hereinafter, a polarizing plate according to another embodiment of the present invention will be described with reference to fig. 5. Fig. 5 is a cross-sectional view of a polarizing plate according to another embodiment of the present invention.

Referring to fig. 5, the polarizing plate (30) may include a first resin layer (210') and a second resin layer (220') sequentially laminated on the polarizing film (100), and is substantially the same as the polarizing plate (10) according to an embodiment of the present invention, except that the refractive index of the second resin layer (220') included in the contrast enhancing layer (200C) is lower than that of the first resin layer (210').

At this time, an absolute value of a refractive index difference between the second resin layer and the first resin layer (refractive index of the first resin layer — refractive index of the second resin layer) may be 0.05 to 0.20, more specifically, 0.06 to 0.15. In this range, the collected light can be well diffused, and the contrast can be greatly improved. In particular, the contrast enhancement layer having the refractive index difference of 0.06 to 0.12 may have an excellent polarization diffusion effect in the optical display device, and may increase luminance even at the same viewing angle. The first resin layer may have a refractive index of 1.50 or more than 1.50, specifically 1.50 to 1.70, 1.50 to 1.60. The second resin layer may have a refractive index of less than 1.52, specifically at least 1.35 and less than 1.50. Within this range, light can be well diffused while facilitating production, and polarized light will be well diffused while improving contrast.

Hereinafter, a polarizing plate according to another embodiment of the present invention will be described with reference to fig. 6. Fig. 6 is a cross-sectional view of a polarizing plate according to another embodiment of the present invention.

Referring to fig. 6, the polarizing plate (40) may include a first resin layer (210') and a second resin layer (220') sequentially laminated on the polarizing film (100), and is substantially the same as the polarizing plate (20) according to another embodiment of the present invention, except that the refractive index of the second resin layer (220') included in the contrast enhancing layer (200C) is lower than that of the first resin layer (210').

The refractive index relationship between the first resin layer and the second resin layer is the same as that described in the polarizing plate (30).

The liquid crystal display device of the present invention may include the polarizing plate of the present invention as a viewer-side polarizing plate with respect to the liquid crystal panel. As used herein, "viewer-side polarizing plate" means a polarizing plate disposed near a screen with respect to a liquid crystal panel.

In one embodiment, the liquid crystal display device may include a backlight unit, a first polarizing plate, a liquid crystal panel, and a second polarizing plate sequentially stacked in this order, and the second polarizing plate may include a polarizing plate according to an embodiment of the present invention. The liquid crystal panel may employ a VA (vertical alignment) mode, an IPS mode, a PVA (patterned vertical alignment) mode, or an S-PVA (super patterned vertical alignment) mode, but is not limited thereto.

Hereinafter, the present invention will be described in more detail with reference to some examples. It should be understood that these examples are provided for illustration only and should not be construed as limiting the invention in any way.

Example 1

A polarizer (thickness: 23 μm) was prepared by: a polyvinyl alcohol film was stretched to 3 times its original length at 60 ℃ and iodine was adsorbed to the stretched film, and then the resulting film was stretched to 2.5 times the stretched length of the film in an aqueous solution of boric acid at 40 ℃.

A polarizing film was prepared by: a Cycloolefin (COP) film (thickness: 50 μm, riston) was adhered to one surface of the polarizer prepared above using an adhesive (Z-200, japan synthesis limited) for a polarizing plate and a triacetyl cellulose (TAC) film (thickness: 60 μm, fuji film) was adhered to the other surface of the polarizer.

The coating was prepared by: an ultraviolet curable resin (SSC-5710, xina T & C) was coated on one surface of the first base layer of an antireflection film (DNP corporation, first base film: TAC film (Re: 0 nm at a wavelength of 550 nm) having a thickness of 60 μm and a minimum reflectance of 0.39%). The engraved pattern and the flat portion are applied to the coating layer using a film including an embossed pattern having two identical bottom corners and a patterned portion of the flat portion located between the embossed patterns, and then cured to prepare a second resin layer including an engraved pattern having two identical bottom corners (an engraved pattern having a trapezoidal cross section as shown in fig. 1) and a patterned portion of the flat portion. A heat-curable adhesive resin (acrylic copolymer, cedon) was coated on the second resin layer to form a first resin layer (self-adhesive property) having a filling pattern completely filling the engraved pattern, and then a laminated plate of the antireflection film and the contrast enhancement layer was formed. Table 1 below shows the detailed specifications of the engraved pattern.

The polarizing film was laminated on one surface of the first resin layer of the laminate to prepare a polarizing plate in which a COP film (thickness: 50 μm), a polarizer (thickness: 23 μm), a TAC film (thickness: 60 μm), a first resin layer (refractive index: 1.48), a second resin layer (refractive index: 1.60) and an antireflection film (first base layer: TAC film having a thickness of 60 μm, minimum reflectance: 0.39%) were sequentially laminated.

Example 2

A polarizing film was prepared in the same manner as in example 1 by the following steps: a COP film (thickness: 50 μm, swiss) was adhered to one surface of a polarizer (thickness: 23 μm) and a PET film (thickness: 80 μm, SRF, donyan) was adhered to the other surface of the polarizer using an adhesive (Z-200, japan synthesis limited).

A contrast enhancement layer was prepared in the same manner as in example 1 on one surface of a PET film (thickness: 80 μm, SRF, Re of 8,000 nm or more, donyan textile) as a second substrate layer.

The first resin layer of the contrast enhancing layer is laminated on one surface of the PET film of the polarizing film.

An antireflection film (DNP Co., Ltd., first base layer: TAC film having a thickness of 60 μm (Re: 0 nm at a wavelength of 550 nm), minimum reflectance of 0.39%) was laminated on the other surface of the second base layer using an adhesive layer (refractive index: 1.48) to prepare a polarizing plate in which a COP film (thickness: 50 μm), a polarizer (thickness: 23 μm), a PET film (thickness: 80 μm), a first resin layer (refractive index: 1.48), a second resin layer (refractive index: 1.60), a PET film as the second base layer (thickness: 80 μm), an adhesive layer (refractive index: 1.48) and an antireflection film (first base layer: TAC film having a thickness of 60 μm, minimum reflectance: 0.39%) were laminated in this order.

Example 3

A polarizing plate was prepared in the same manner as in example 2, except that the PET film included in the polarizing film and the PET film as the second base layer were respectively changed to TAC films (thickness: 60 micrometers, fuji film) and the antireflection film was changed to the antireflection film (TAC film (Re: 0 nanometers at a wavelength of 550 nanometers) as the first base film and having a thickness of 60 micrometers, minimum reflectance: 0.29%, letterpress co.

Example 4

A polarizing plate was prepared in the same manner as in example 2, except that the PET film included in the polarizing film and the PET film as the second base layer were respectively changed to TAC films (thickness: 60 micrometers, fuji film) and the anti-reflection film was changed to the anti-reflection film (TAC film as the first base film and having a thickness of 60 micrometers, minimum reflectance: 0.19%, letterpress limited).

Example 5

A polarizing plate was prepared in the same manner as in example 2 except that the PET film included in the polarizing film and the PET film as the second base layer were respectively changed to TAC films (thickness: 60 micrometers, fuji film), and the second resin layer was changed to a second resin layer having a refractive index of 1.54 using an ultraviolet curable resin (SSC-5100, xina T & C), while the antireflection film was changed to an antireflection film (TAC film (Re: 0 nanometers at a wavelength of 550 nanometers) as the first base film and having a thickness of 60 micrometers, minimum reflectance: 0.19%, letterpress limited).

Example 6

A polarizing plate was produced in the same manner as in example 2 except that the antireflection film was changed to an antireflection film (TAC film (Re: 0 nm at a wavelength of 550 nm) as a first base film and having a thickness of 60 μm, minimum reflectance: 0.19%, letterpress co.

Example 7

A polarizing plate was prepared in the same manner as in example 2, except that the second resin layer was changed to a second resin layer having a refractive index of 1.54 using an ultraviolet curable resin (SSC-5100, xina T & C), and the antireflection film was changed to an antireflection film (TAC film as a first base film and having a thickness of 60 μm, minimum reflectance: 0.19%, letterpress co.).

Example 8

A polarizing plate was produced in the same manner as in example 2, except that the antireflection film was changed to an antireflection film (TAC film as the first base film and having a thickness of 60 μm, minimum reflectance: 0.09%, letterpress co., ltd.).

Example 9

A polarizer was prepared in the same manner as in example 1.

A polarizing film was prepared by: a COP film (thickness: 50 μm, rhorn) was adhered to one surface of the polarizer prepared above using an adhesive (Z-200, japan synthesis limited) for a polarizing plate and a PET film (thickness: 80 μm, SRF, relief) was adhered to the other surface of the polarizer.

The coating was prepared by: an ultraviolet curable resin (SSC-4560, xina T & C) was coated on one surface of the first base layer of an antireflection film (relief co., first base film: TAC film (Re: 0 nm at a wavelength of 550 nm) having a thickness of 60 μm, minimum reflectance: 0.29%). The engraved pattern and the flat portion are applied to the coating layer using a film including an embossed pattern having two identical bottom corners and a patterned portion of the flat portion located between the embossed patterns, and then cured to prepare a second resin layer including an engraved pattern having two identical bottom corners (an engraved pattern having a trapezoidal cross section as shown in fig. 1) and a patterned portion of the flat portion. An ultraviolet curable resin (SSC-5710, xina T & C) is coated on the second resin layer to form a first resin layer (self-adhesive property) having a filling pattern completely filling the engraved pattern, and then a laminated board of the antireflection film and the contrast enhancement layer is formed. Table 1 below shows the detailed specifications of the engraved pattern.

The polarizing film was laminated on one surface of the first resin layer of the laminate to prepare a polarizing plate in which a COP film (thickness: 50 μm), a polarizer (thickness: 23 μm), a PET film (thickness: 80 μm), a first resin layer (refractive index: 1.60), a second resin layer (refractive index: 1.48) and an antireflection film (first base layer: TAC film having a thickness of 60 μm, minimum reflectance: 0.29%) were laminated in this order.

Example 10

A polarizing film was prepared in the same manner as in example 9 by the following steps: a COP film (thickness: 50 μm, roly) was adhered to one surface of the polarizer (thickness: 23 μm) prepared above using an adhesive (Z-200, japan synthesis limited) for a polarizing plate and a PET film (thickness: 80 μm, SRF, relief) was adhered to the other surface of the polarizer.

A contrast enhancement layer was formed on one surface of a PET film (thickness: 80 μm, SRF, Re: 8,000 nm or more than 8,000 nm, eastern ocean) as a second substrate layer in the same manner as in example 9.

A first resin layer was laminated on one surface of a PET film of a polarizing film, and an antireflection film (letterpress, Ltd., first base layer: a TAC film (Re: 0 nm at a wavelength of 550 nm) having a thickness of 60 μm, minimum reflectance: 0.09%) was laminated on the other surface of a second base layer through an adhesive (refractive index: 1.48) to prepare a polarizing plate in which a COP film (thickness: 50 μm), a polarizer (thickness: 23 μm), a PET film (thickness: 80 μm), a first resin layer (refractive index: 1.60), a second resin layer (refractive index: 1.48), a PET film (thickness: 80 μm) as the second base layer, an adhesive layer (refractive index: 1.48) and an antireflection film (first base layer: a TAC film having a thickness of 60 μm, minimum reflectance: 0.09%) were laminated in this order.

Comparative example 1

A polarizing plate was prepared in the same manner as in example 1, except that the contrast enhancing layer was not formed.

Comparative example 2

A polarizing plate was prepared in the same manner as in example 1, except that an antireflection film (TAC film as the first base layer, minimum reflectance of 1%) was used as the antireflection film.

Comparative example 3

A polarizing plate was prepared in the same manner as in example 1, except that an antireflection film (TAC film as the first base layer, minimum reflectance 0.46%) was used as the antireflection film.

Comparative example 4

A polarizing plate was prepared in the same manner as example 1, except that a contrast enhancing layer having an engraved pattern shown in table 1 below was used. The patterned portion has a value of 6.21 as represented by equation 1 above.

Comparative example 5

A polarizing plate was prepared in the same manner as example 1, except that a contrast enhancing layer having an engraved pattern shown in table 1 below was used. The patterned portion does not have a flat portion.

Comparative example 6

A polarizing plate was prepared in the same manner as example 1, except that a contrast enhancing layer having an engraved pattern shown in table 1 below was used. The engraved pattern has a base angle of 67.4 °.

[ Table 1]

The properties of the polarizing plates of the examples and comparative examples listed in table 2 were evaluated. The results are shown in table 2, fig. 7 and fig. 8.

(1) Reflectance ratio: a black acrylic sheet (larex, ritonggshiki industries, ltd.) was laminated on the polarizing film of the polarizing plate of each of the examples and comparative examples to prepare a sample. The light was measured in SCI reflection mode (illuminant: D65, illuminant diameter:

25.4 mm, measurement viewing angle: 2 deg.) the reflectance was measured at 10 nm intervals over a wavelength range of 360 nm to 740 nm. A reflectance at a wavelength of 500 nm and a reflectance at a wavelength of 600 nm were obtained.

(2) Reflectance slope: the reflectance slope is calculated according to the above equation 2 using the reflectance measured in the reflectance (1).

(3) Light reflectance: a sample was prepared in the same manner as the reflectance (1), and the light reflectance Y (D65) was evaluated under the following conditions.

The device comprises the following steps: spectrophotometer CM-3600A

Light source: d65 light source

Diameter of light source

25.4 mm

And (3) measuring a visual angle: 2 degree

(4) Appearance evaluation: the polarizing plate of each of the examples and comparative examples was placed on a liquid crystal panel so that the antireflection film was directed uppermost, and a 3-primary color fluorescent lamp (osram) was placed at a height of 30 cm with respect to the antireflection film, followed by illumination, visual evaluation, and scoring of visual appearance. The scores were evaluated from 1 point to 5 points. When the score was shifted from 5 to 1 point, the appearance was improved. Score 5 shows that the reflected light is split and the black visual acuity is poor, and score 1 shows that the reflected light is not split and the black visual acuity is good. A score of 5 means that this device cannot be used for a display device because of poor black visual acuity.

(5) Relative brightness and opposite side contrast: a module of a liquid crystal display device was manufactured, and the relative brightness and the opposite-side contrast were evaluated in the following manner.

Preparation example 1: preparation of first polarizing plate

A first polarizer was prepared by: a polyvinyl alcohol film was stretched to 3 times its original length at 60 ℃ and iodine was adsorbed to the stretched film, and then the resulting film was stretched to 2.5 times the stretched length of the film in an aqueous solution of boric acid at 40 ℃. The first polarizing plate was prepared by adhering a triacetyl cellulose film (thickness of 80 μm) as a base layer to both surfaces of the first polarizer using an adhesive (Z-200, japan synthesis limited) for a polarizing plate.

Preparation example 2: preparation of modules for liquid crystal display devices

The first polarizing plate of preparation example 1, the liquid crystal panel (PVA mode), and each of the polarizing plates prepared in examples and comparative examples were sequentially assembled to prepare a module of a liquid crystal display device. Each of the polarizing plates prepared in examples and comparative examples was used as a viewer-side polarizing plate and an antireflection film was disposed at the outermost side of the viewer side.

The modules of the LED light source, the light guide plate, and the liquid crystal display device were assembled to prepare a liquid crystal display device including a double-sided edge type LED light source having the same configuration as that of samsung LED TV (UN55KS800) except for the configuration of the module of the liquid crystal display device prepared in the example and the comparative example. The front luminance was measured in a spherical coordinate system (0 ° ) in white mode (white mode) and black mode (black mode) using EZCONTRAST X88RC (EZXL-176R-F422a4, aldeim). The relative luminance is calculated as { (luminance in example or comparative example)/(luminance in comparative example 1) } × 100. The target relative brightness is 90% or more than 90%.

Lateral contrast was measured in a spherical coordinate system (0 °,60 °) using EZCONTRAST X88RC (EZXL-176R-F422a4, allem). The opposite-side contrast was calculated as { (side contrast in example or comparative example)/(side contrast in comparative example 1) } × 100. The target-side contrast is 110% or greater than 110%.

[ Table 2]

As shown in table 1, the polarizing plate of the example has improved black visual acuity and appearance as well as improved visibility and increased side contrast even when external light such as sunlight or lamp light is irradiated.

On the other hand, the polarizing plate of the comparative example, which deviates from the scope of the present invention, has poor appearance, side contrast and visibility.

While certain embodiments of the present invention have been illustrated and described, it will be appreciated that various modifications, changes, alterations, and equivalents may be made by those skilled in the art without departing from the spirit and scope of the invention as defined in the claims. It is to be understood that various modifications, alterations, adaptations, and equivalent embodiments may occur to one skilled in the art without departing from the spirit and scope of the present invention.