Adhesive composition for polarizing plate, polarizing plate including the same and optical display including the same

1. A polarizing plate comprising an adhesive film for polarizing plates, the adhesive film being formed from an adhesive composition for polarizing plates, the adhesive composition including:

a tertiary amine group-containing (meth)acrylic copolymer;

a cellulose resin;

an isocyanate compound; and

a metal chelate compound.

2. The polarizing plate as claimed in claim 1 , wherein the adhesive composition has a gel fraction of about 50% or more after 12-hour aging, as calculated according to the following equation:

Gel fraction=( WC−WA )/( WB−WA )×100,

wherein WA is a weight of a wire mesh; WB is a total weight of the wire mesh and a specimen of an adhesive film for polarizing plates, which is obtained by depositing 1.0 g of an adhesive composition for polarizing plates to a thickness of 20 μm on a release film, followed by aging the adhesive composition for polarizing plates on the release film at 23° C. and 55% RH for 12 hours, and then is placed on the wire mesh; and WC is a total weight of the wire mesh and the adhesive film, which are placed in a sample bottle, left for 1 day after adding 50 cc of ethyl acetate to the sample bottle, and then dried at 90° C. for 24 hours.

3. The polarizing plate as claimed in claim 2 , wherein the adhesive composition has an absolute value of a difference between a gel fraction after 12-hour aging and a gel fraction after 48-hour aging of about 5% or less.

4. The polarizing plate as claimed in claim 1 , wherein the adhesive composition includes:

100 parts by weight of the tertiary amine group-containing (meth)acrylic copolymer;

about 3 parts by weight to about 10 parts by weight of the cellulose resin;

about 0.05 parts by weight to about 5 parts by weight of the isocyanate compound; and

about 0.01 parts by weight to about 10 parts by weight of the metal chelate compound.

5. The polarizing plate as claimed in claim 1 , wherein the tertiary amine group-containing (meth)acrylic copolymer includes about 0.01 wt % to about 5 wt % of (meth)acrylic repeat units having a tertiary amine group, based on a total weight of repeat units in the copolymer.

6. The polarizing plate as claimed in claim 1 , wherein the tertiary amine group-containing (meth)acrylic copolymer is prepared by copolymerization of a monomer mixture, the monomer mixture including:

a hydroxyl group-containing (meth)acrylic monomer,

a tertiary amine group-containing (meth)acrylic monomer, and

a monomer having a glass transition temperature Tg of about 100° C. or higher.

7. The polarizing plate as claimed in claim 6 , wherein the monomer mixture further includes an alkyl group-containing (meth)acrylic monomer.

8. The polarizing plate as claimed in claim 6 , wherein the tertiary amine group-containing (meth)acrylic monomer includes N,N-(dimethylamino)ethyl (meth)acrylate or N,N-(diethylamino)ethyl (meth)acrylate.

9. The polarizing plate as claimed in claim 6 , wherein the monomer having a glass transition temperature Tg of about 100° C. or more includes (meth)acryloyl morpholine, N-vinylpyrrolidone, or isobornyl (meth)acrylate.

10. The polarizing plate as claimed in claim 7 , wherein the monomer mixture includes:

about 0.1 wt % to about 20 wt % of the hydroxyl group-containing (meth)acrylic monomer,

about 0.01 wt % to about 5 wt % of the tertiary amine group-containing (meth)acrylic monomer,

about 1 wt % to about 30 wt % of the monomer having a glass transition temperature Tg of about 100° C. or more, and

about 60 wt % to about 95 wt % of the alkyl group-containing (meth)acrylic monomer.

11. The polarizing plate as claimed in claim 1 , wherein the tertiary amine group-containing (meth)acrylic copolymer has a glass transition temperature of about −45° C. to about −30° C.

12. The polarizing plate as claimed in claim 1 , wherein the cellulose resin is cellulose acetate butyrate.

13. The polarizing plate as claimed in claim 1 , wherein the cellulose resin includes about 1 wt % to about 10 wt % of a hydroxyl group, based on a total weight of the cellulose resin.

14. The polarizing plate as claimed in claim 1 , wherein the metal chelate compound is a tin-based chelate compound or an aluminum-based chelate compound.

15. The polarizing plate as claimed in claim 1 , wherein a weight ratio of the isocyanate compound to the metal chelate compound is 1:0.05 to 1:5.

16. The polarizing plate as claimed in claim 1 , wherein the adhesive composition further includes a silane coupling agent or a reworking agent.

17. The polarizing plate as claimed in claim 16 , wherein:

the adhesive composition includes the silane coupling agent, and

the silane coupling agent includes an acetoacetyl group-containing silane coupling agent.

18. An optical display comprising the polarizing plate as claimed in claim 1 .