Polarizing plate and image display apparatus comprising same

1. A polarizing plate comprising:

a polarizer; and

a protective layer formed on at least one surface of the polarizer,

wherein the protective layer is a cured product of a radical curable composition comprising: (A) an acid anhydride-based compound having at least one unsaturated double bond between carbons; (B) a vinyl-based compound having at least one electron donor group; (C) a radical initiator; and (D) a cation generator.

2. The polarizing plate of claim 1 , wherein in the polarizer and the protective layer, adhesive strength is secured through a covalent bond generated as a result of an esterification reaction between a hydroxy group of the polarizer and an acid anhydride group of the protective layer.

3. The polarizing plate of claim 1 , wherein in terms of a content of the acid anhydride-based compound and the vinyl-based compound, a blending equivalent ratio represented by the following Equation (1) is 0.8 to 1.0;

Blending equivalent ratio= M/N,   Equation (1):

wherein in Equation (1), M is the number of unsaturated double bonds between carbons, which are capable of participating in a polymerization in a molecule comprising an acid anhydride group comprised in the acid anhydride-based compound; and N is the number of unsaturated double bonds between carbons, which are capable of participating in a polymerization in a molecule comprised in the vinyl-based compound.

4. The polarizing plate of claim 1 , wherein the acid anhydride-based compound is one or more compounds selected from the group consisting of compounds represented by the following [Formula I] to [Formula IV]:

wherein in [Formula I], R 1 is a (meth)acryloyl group, a (meth)acryloylalkyl group, or a (meth)acryloyloxy alkyl group; R 2 is a halogen atom or a C 1˜10 alkyl group; a is an integer of 1 and 2; b is an integer of 0 to 2; and X 1 is a single bond, —O—, —CO—, —COO—, or —OCO—,

wherein in [Formula II], R 3 to R 5 are each independently hydrogen or a halogen atom; or a C 1˜10 alkyl group, a C 4˜14 cycloalkyl group, a C 6˜14 aryl group or a combination thereof,

wherein in [Formula III], R 6 and R 7 are each independently hydrogen or a halogen atom; or a C 1˜10 alkyl group, a C 4˜14 cycloalkyl group, a C 6˜14 aryl group or a combination thereof, and

wherein in [Formula IV], R 8 to R 11 are each independently hydrogen or a halogen atom; or a C 1˜10 alkyl group, a C 4˜14 cycloalkyl group, a C 6˜14 aryl group or a combination thereof.

5. The polarizing plate of claim 1 , wherein the electron donor group of the vinyl-based compound is a functional group represented by the following [Formula A] or [Formula B]:

wherein in [Formula A], R 12 is hydrogen or a C 1˜10 alkyl group, and

wherein in [Formula B], R 13 is hydrogen or a C 1˜10 alkyl group.

6. The polarizing plate of claim 1 , wherein the vinyl-based compound is a compound represented by the following [Formula V]:

wherein in [Formula V], R 14 is hydrogen or a C 1˜10 alkyl group; R 15 is a c-valent C 1˜10 aliphatic chain, a C 4˜14 aliphatic ring, a C 6˜14 aromatic ring, or a combination thereof; c is an integer of 1 to 4; and X 2 is —O— or —OCO—.

7. The polarizing plate of claim 1 , wherein the radical curable composition further comprises a radical polymerizable compound represented by the following [Formula VI]:

wherein in [Formula VI], R 16 is an ester group (—COO—), an amide group (—CON—), or a thioate group (—COS—); R 17 is a C 1˜10 alkyl group, a C 4˜10 cycloalkyl group, or a combination thereof, and in this case, R 17 has at least one hydroxy substituent in a molecule thereof; and R 18 is hydrogen, or a C 1˜10 alkyl group.

8. The polarizing plate of claim 7 , wherein the radical curable composition comprises 1 to 50 parts by weight of the acid anhydride-based compound and the vinyl-based compound; 40 to 97 parts by weight of the radical polymerizable compound; 1 to 10 parts by weight of the radical initiator; and 1 to 10 parts by weight of the cation generator based on 100 parts by weight of the entire composition.

9. The polarizing plate of claim 1 , wherein the radical curable composition after curing has a glass transition temperature of 60° C. or more.

10. The polarizing plate of claim 1 , wherein the radical curable composition has a viscosity of 10 to 200 cP.

11. The polarizing plate of claim 1 , wherein the protective film has a thickness of 0.5 to 20 μm.

12. The polarizing plate of claim 1 , wherein a protective film is further attached, through an adhesive layer, to a surface opposite to a surface of the polarizer, on which said protective layer is formed previously.

13. The polarizing plate of claim 1 , further comprising an adhesion layer at an upper portion of the protective layer.

14. The polarizing plate of claim 1 , wherein the polarizer is a polyvinyl alcohol-based film comprising iodine or a dichroic dye.

15. An image display device comprising the polarizing plate of claim 1 .