Polarizing plate and liquid crystal display device including same
Provided are a polarizing plate and a liquid crystal display device including same, the polarizing plate including a polarization film, a contrast-improving layer, and an anti-reflection film that are sequentially laminated. The minimum reflectance of the anti-reflection film is no greater than 0.45%. The anti-reflection film has a first substrate layer, a high-refraction layer and a low-refraction layer that are laminated in order from the contrast-improving layer. The contrast-improving layer includes a first resin layer and a second resin layer facing the first resin layer. The second resin layer is provided with a pattern part having optical patterns and a flat part between the optical patterns. The pattern part satisfies Equation 1 and the optical patterns have a base angle (θ) of 75° to 90°. The slope of the reflectance of the polarization plate in Equation 2 is no greater than 0.3.
1. A polarizing plate comprising a polarizing film, a contrast ratio enhancing layer, and an antireflection film, which are sequentially laminated in this order,
the antireflection film having minimum reflectance of 0.45% or less,
the antireflection film comprising a first base layer, a high refractive index layer, and a low refractive index layer, which are sequentially laminated on the contrast ratio enhancing layer in this order,
the contrast ratio enhancing layer comprises a first resin layer and a second resin layer facing the first resin layer, wherein the second resin layer comprises a patterned portion including optical patterns and a flat portion formed between the optical patterns,
the patterned portion satisfying following Equation 1,
each optical pattern having a base angle θ of 75° to 90°:
1 <P/B≤ 6 [Equation 1]
wherein, P is a pitch of the patterned portion, (unit: μm), and
B is a maximum width of the flat portion, (unit: μm),
the polarizing plate having a reflectance slope of 0.3 or less according to following Equation 2:
Reflectance slope=| R 600 −R 500 |/|600−500|×100 [Equation 2]
wherein, R 600 is a reflectance value of the polarizing plate at a wavelength of 600 nm, and
R 500 is a reflectance value of the polarizing plate at a wavelength of 500 nm.
2. The polarizing plate of claim 1 , wherein the polarizing plate has luminous reflectance of 2% or less.
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 layer.
4. The polarizing plate of claim 1 , wherein an absolute value of a refractive index difference between the first resin layer and the second resin layer is 0.05 to 0.20.
5. The polarizing plate of claim 1 , wherein a refractive index of the second resin layer is higher or lower than a refractive index of the first resin layer.
6. The polarizing plate of claim 1 , wherein each optical pattern has an aspect ratio of 0.3 to 3.0.
7. The polarizing plate of claim 1 , wherein the first resin layer has a self-adhesive property and the first resin layer is formed directly on the polarizing film.
8. The polarizing plate of claim 1 , wherein at least one of an adhesive layer, a bonding layer, and a protective film is further formed between the contrast ratio enhancing layer and the polarizing film.
9. The polarizing plate of claim 1 , wherein the high refractive index layer has a refractive index of 1.53 to 1.70.
10. The polarizing plate of claim 1 , wherein the first base layer is formed directly on the contrast ratio enhancing layer and wherein the first base layer has an in-plane retardation Re of 60 nm or less at a wavelength of 550 nm.
11. The polarizing plate of claim 1 , wherein each optical pattern comprises an engraved pattern, the engraved pattern comprising a first surface at a top part and at least one inclined surface connected to the first surface, the inclined surface comprising a flat or curved optical pattern.
12. The polarizing plate of claim 11 , wherein the first surface is flat and the first surface is formed to be parallel to the flat portion.
13. 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 including at least one of a fluorene-based compound and a biphenyl-based compound, a UV curable compound, an initiator, and an inorganic particle.
14. The polarizing plate of claim 13 , wherein the inorganic particle comprises zirconia.
15. The polarizing plate of claim 13 , wherein the composition for the high refractive index layer further comprises an antistatic agent.
16. The polarizing plate of claim 1 , wherein a second base layer is further formed between the contrast ratio enhancing layer and the antireflection film.
17. The polarizing plate of claim 16 , wherein an adhesive layer is further formed between the contrast ratio enhancing layer and the antireflection film.
18. The polarizing plate of claim 17 , wherein the adhesive layer has a refractive index of 1.40 to 1.65.
19. The polarizing plate of claim 17 , wherein the second base layer and the adhesive layer are sequentially formed between the contrast ratio enhancing layer and the antireflection film,
the second base layer having an in-plane retardation Re of 8,000 nm or more at a wavelength of 550 nm,
the adhesive layer having a refractive index of 1.40 to 1.65.
20. The polarizing plate of claim 19 , wherein the first base layer has an in-plane retardation Re of 60 nm or less at a wavelength of 550 nm.
21. A liquid crystal display device comprising a polarizing plate according to claim 1 .