Polarizing plate and optical display device comprising same
Provided are a polarizing plate and an optical display device comprising the same, wherein the polarizing plate has a polarizing film, a first adhesive layer, a first optical compensation layer, a second adhesive layer, and a second optical compensation layer laminated successively, and elastic modulus measured by a microindenter at 25° C. on the surface of the second optical compensation layer with regard to the polarizing plate is about 100 MPa to about 1000 MPa.
1. A polarizing plate comprising:
a polarizing film, a first adhesive layer, a first optical compensation layer, a second adhesive layer, and a second optical compensation layer stacked in the stated order,
wherein the polarizing plate has an elastic modulus of about 100 MPa to about 1,000 MPa, as measured on a surface of the second optical compensation layer at 25° C. using a microindenter,
wherein the second adhesive layer has a tensile modulus of about 0.1 MPa to about 3 MPa at 25° C.
2. The polarizing plate according to claim 1 , wherein the first adhesive layer has higher tensile modulus than the second adhesive layer at 25° C.
3. The polarizing plate according to claim 1 , wherein the first adhesive layer has a tensile modulus of higher than about 1 MPa and about 220 MPa or less at 25° C.
4. The polarizing plate according to claim 1 , wherein the first adhesive layer is formed of an adhesive layer composition comprising an adhesive resin having a glass transition temperature of 50° C. or higher, as measured before curing, and an isocyanate based curing agent,
the isocyanate based curing agent being present in an amount of about 5 parts by weight to about 50 parts by weight relative to 100 parts by weight of the adhesive resin.
5. The polarizing plate according to claim 4 , wherein the isocyanate based curing agent comprises a polyisocyanate based curing agent modified with an allophanate group.
6. The polarizing plate according to claim 1 , wherein the first adhesive layer is formed of an adhesive layer composition comprising a (meth)acrylic copolymer having a glass transition temperature of 0° C. or less, as measured before curing, and an isocyanate based curing agent,
the isocyanate based curing agent being present in an amount of more than about 5 parts by weight and about 30 parts by weight or less relative to 100 parts by weight of the (meth)acrylic copolymer.
7. The polarizing plate according to claim 1 , wherein the second adhesive layer is formed of an adhesive layer composition comprising a (meth)acrylic copolymer having a glass transition temperature of 0° C. or less, as measured before curing, and an isocyanate based curing agent,
the isocyanate based curing agent being present in an amount of about 0.001 parts by weight to about 10 parts by weight relative to 100 parts by weight of the (meth)acrylic copolymer.
8. The polarizing plate according to claim 1 , wherein the first optical compensation layer has an in-plane retardation Re of about 225 nm to about 350 nm at a wavelength of 550 nm, as calculated according to Equation 1:
Re=( nx−ny )× d <Equation 1>
wherein nx and ny are refractive index of the first optical compensation layer in the x and y axis directions at a wavelength of 550 nm, respectively, and d indicates a thickness (unit: nm) of the first optical compensation layer.
9. The polarizing plate according to claim 1 , wherein the first optical compensation layer is a liquid crystal film or a liquid crystal coating layer.
10. The polarizing plate according to claim 9 , wherein the first adhesive layer is formed directly on the first optical compensation layer.
11. The polarizing plate according to claim 9 , wherein at least one of the first optical compensation layer and the second optical compensation layer has a thickness of about 1 μm to about 10 μm.
12. The polarizing plate according to claim 9 , wherein the second optical compensation layer has an in-plane retardation Re of about 100 nm to about 220 nm at a wavelength of 550 nm, as calculated according to Equation 1:
Re=( nx−ny )× d <Equation 1>
wherein nx and ny are refractive index of the second optical compensation layer in the x and y axis directions at a wavelength of 550 nm, respectively, and d indicates a thickness (unit: nm) of the second optical compensation layer.
13. The polarizing plate according to claim 1 , wherein at least one of the first adhesive layer and the second adhesive layer comprises a UV absorber, the UV absorber comprising an indole-based UV absorber having a melting point of about 100° C. or higher.
14. The polarizing plate according to claim 13 , wherein the UV absorber has a maximum absorption wavelength of higher than about 390 nm and about 400 nm or less.
15. The polarizing plate according to claim 13 , wherein the UV absorber is present in an amount of about 0.05 wt % to about 5 wt % in the first adhesive layer.
16. The polarizing plate according to claim 13 , wherein the polarizing plate has a light transmittance of about 3% or less at a wavelength of 405 nm or less.
17. An optical display comprising the polarizing plate according to claim 1 .