Polarizing plate
Provided are a polarizing plate and a liquid crystal display device. The polarizing plate has lighter weight, a smaller thickness, and excellent physical properties such as water resistance, workability, durability, and light leakage preventing ability. In addition, the polarizing plate prevents curling occurring at the polarizing plate or a polarizer in formation thereof, and has excellent thermal resistance or thermal shock resistance.
1. A polarizing plate, comprising:
a polarizer;
an adhesive layer formed of an active energy beam-curable adhesive, having a thickness of 0.1 to 30 μm; and
a pressure-sensitive adhesive layer having a thickness of 10 to 80 μm, which are sequentially disposed,
wherein the pressure-sensitive adhesive layer has first and second surfaces, the first surface having a higher tensile modulus than the second surface,
wherein the first surface of the pressure-sensitive adhesive layer is directly attached to a surface of the adhesive layer, and has a surface swollen by single-molecular reactive material of the active energy beam-curable adhesive, before the active energy beam-curable adhesive is cured,
wherein the pressure-sensitive adhesive layer comprises an interpenetrating polymer network including a crosslinked structure including an acryl resin crosslinked by a multifunctional crosslinking agent, and a crosslinked structure including polymerized multifunctional acrylate,
wherein the surface of the adhesive layer which is opposite to the surface directly attached to the pressure-sensitive adhesive layer, is directly attached to a surface of the polarizer, and
wherein the first surface of the pressure-sensitive adhesive layer has a tensile modulus at 25° C. of 100 to 500 MPa and the second surface of the pressure-sensitive adhesive layer has a tensile modulus at 25° C. of 0.02 to 0.3 MPa.
2. The polarizing plate according to claim 1 , wherein the adhesive layer includes an adhesive composition including an epoxy compound and/or an acryl-based monomer in a cured state.
3. The polarizing plate according to claim 2 , wherein the adhesive composition has a glass transition temperature after curing of 50° C. or more.
4. The polarizing plate according to claim 2 , wherein the epoxy compound includes an alicyclic epoxy compound and/or a glycidyl ether-type epoxy compound.
5. The polarizing plate according to claim 2 , wherein the epoxy compound has a weight average molecular weight of 1,000 to 5,000.
6. The polarizing plate according to claim 2 , wherein the acryl-based monomer is a hydrophilic acryl-based monomer or a hydrophobic acryl-based monomer.
7. The polarizing plate according to claim 6 , wherein the hydrophilic acryl-based monomer has a hydroxyl group, a carboxyl group or an alkoxy group.
8. The polarizing plate according to claim 2 , wherein the adhesive composition further includes 1 to 40 parts by weight of a reactive oligomer.
9. The polarizing plate according to claim 2 , wherein the adhesive composition is a non-solvent type.
10. The polarizing plate according to claim 2 , wherein the adhesive composition has a viscosity of 5 to 1,000 cps at 25° C.
11. The polarizing plate according to claim 1 , wherein the acryl resin includes a (meth)acrylic acid ester-based monomer in a polymerization unit.
12. The polarizing plate according to claim 11 , wherein the acryl resin further includes a monomer represented by Formula 16 in a polymerization unit:
where R is hydrogen or an alkyl group, A is alkylene, R 24 is an alkyl group or an aryl group, and n is a number between 1 and 6.
13. The polarizing plate according to claim 1 , further comprising:
a protective film attached to a surface of the polarizer opposite a surface to which the pressure-sensitive adhesive layer is attached.
14. A liquid crystal display device, comprising:
a liquid crystal panel; and
the polarizing plate according to claim 1 attached to one or both surfaces of the liquid crystal panel.
15. The device according to claim 14 , wherein the liquid crystal panel is attached to the pressure-sensitive adhesive layer.