Polarizing Plate and Image Display Device Comprising the Same
A polarizing plate and an image display device including the same are provided. The polarizing plate includes a polarizer; and a protective layer in contact with at least one surface of the polarizer. The protective layer is a cured material of a photocurable composition including a photopolymerizable compound; a photoinitiator; a photosensitizer; and an auxiliary photosensitizer. The photopolymerizable compound consists of a first epoxy-based compound, a second epoxy-based compound and an oxetane compound.
1 . A polarizing plate comprising:
a polarizer; and
a protective layer in contact with at least one surface of the polarizer,
wherein the protective layer is a cured material of a photocurable composition for a polarizing plate protective layer comprising a photopolymerizable compound; a photoinitiator; a photosensitizer; and an auxiliary photosensitizer, wherein the photopolymerizable compound consists of a first epoxy-based compound, a second epoxy-based compound and an oxetane compound;
the protective layer has storage modulus of 1,500 MPa to 10,000 MPa at 80° C.;
the protective layer has a thickness of 5 μm to 10 μm; and
a yellowing scale value (b) of the protective layer measured by the following Equation 1 has an increase rate of 0.05 to 0.3 compared to an initial value (S) under a condition of a temperature of 25° C. and relative humidity (RH) of 40%:
increase rate of yellowing scale value ( b )=yellowing scale value ( b ) of protective layer coated on polarizer−initial value ( S , yellowing scale value ( b ) of polarizer without protective layer). [Equation 1]
2 . The polarizing plate of claim 1 , wherein the protective layer is formed on the polarizer by coating.
3 . The polarizing plate of claim 1 , wherein the first epoxy-based compound is an alicyclic epoxy-based compound.
4 . The polarizing plate of claim 1 , wherein the second epoxy-based compound is an aliphatic epoxy-based compound.
5 . The polarizing plate of claim 1 , wherein the first epoxy-based compound is included in 50 parts by weight to 70 parts by weight with respect to a total 100 parts by weight of the photopolymerizable compound.
6 . The polarizing plate of claim 1 , wherein the second epoxy-based compound is included in 10 parts by weight to 20 parts by weight with respect to a total 100 parts by weight of the photopolymerizable compound.
7 . The polarizing plate of claim 1 , wherein the oxetane compound is included in 10 parts by weight to 30 parts by weight with respect to a total 100 parts by weight of the photopolymerizable compound.
8 . The polarizing plate of claim 1 , wherein the photoinitiator is an iodine-based compound absorbing a wavelength of 310 nm or lower.
9 . The polarizing plate of claim 1 , wherein the photosensitizer is an anthracene-based compound absorbing a wavelength of 380 nm or higher.
10 . The polarizing plate of claim 1 , wherein the auxiliary photosensitizer is a naphthalene-based compound.
11 . The polarizing plate of claim 1 , wherein the photoinitiator is included in 2 parts by weight to 5 parts by weight with respect to a total 100 parts by weight of the photocurable composition for a polarizing plate protective layer.
12 . The polarizing plate of claim 1 , wherein the photosensitizer is included in 0.1 parts by weight to 0.5 parts by weight with respect to a total 100 parts by weight of the photocurable composition for a polarizing plate protective layer.
13 . The polarizing plate of claim 1 , wherein the auxiliary photosensitizer is included in 1 parts by weight to 3 parts by weight with respect to a total 100 parts by weight of the photocurable composition for a polarizing plate protective layer.
14 . The polarizing plate of claim 1 , wherein the photocurable composition for a polarizing plate protective layer has viscosity of greater than or equal to 50 cps and less than or equal to 200 cps at 25° C.
15 . The polarizing plate of claim 1 , wherein a protective film is attached on a surface opposite to the at least one surface in contact with the protective layer of the polarizer using an adhesive layer.
16 . The polarizing plate of claim 15 , wherein the adhesive layer is a cured material of an adhesive composition, and the adhesive composition comprises an epoxy compound and an oxetane compound.
17 . An image display device comprising the polarizing plate of claim 1 .