Polarizing plate, image display apparatus comprising same, and adhesive composition for polarizing plate

1. A polarizing plate, comprising:

a polarizer;

a protective layer directly formed on one surface of the polarizer; and

an adhesive layer and a protective film consecutively provided on a surface of the polarizer on which the protective layer is not formed,

wherein the protective film is a polyethylene terephthalate (PET) film, a cycloolefin polymer (COP) film, or an acryl-based film,

wherein the adhesive layer is a resin layer comprising an active energy ray-curable composition comprising a first epoxy compound (A) comprising one or more alicyclic epoxy rings, and, with respect to 100 parts by weight of the first epoxy compound (A), a second epoxy compound (B) comprising one or more glycidyl ether groups in 140 parts by weight to 500 parts by weight and an oxetane compound (C) in 5 parts by weight to 85 parts by weight, or a cured material thereof, and

wherein a peel strength of the adhesive layer satisfies the following General Formula 1,

P ≥3.5 N/cm  [General Formula 1]

in General Formula 1, P is the peel strength of the adhesive layer and is measured by peeling the protective film from the adhesive layer at 25° C. at a peeling angle of 90° and a peeling rate of 300 mm/min.

2. The polarizing plate of claim 1 , wherein the adhesive layer has storage modulus of 700 Mpa to 1,600 Mpa at 80° C. under a measurement condition of a temperature range of −30° C. to 160° C., a temperature raising rate of 5° C./min, a frequency of 1 Hz and strain of 10%.

3. The polarizing plate of claim 1 , wherein, as a result of a high temperature crack growth test on the polarizer, a ratio of the number of light leaking cracks (C2) with respect to the number of total cracks (C1) is 20% or less.

4. The polarizing plate of claim 1 , wherein the adhesive layer has a glass transition temperature of 90° C. or higher.

5. The polarizing plate of claim 1 , wherein the adhesive layer has a thermal expansion coefficient of 130 ppm/K or less at 80° C.

6. The polarizing plate of claim 1 , wherein the adhesive layer has a thickness of greater than or equal to 0.5 μm and less than or equal to 8 μm.

7. The polarizing plate of claim 1 , wherein the protective layer has a thickness of greater than or equal to 4 μm and less than or equal to 11 μm.

8. The polarizing plate of claim 1 , which does not further comprise a protective film on the other surface of the polarizer-facing surface of the protective layer.

9. The polarizing plate of claim 1 , further comprising a gluing layer on the other surface of the polarizer-facing surface of the protective layer.

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

11. An adhesive composition for a polarizing plate comprising:

a first epoxy compound (A) comprising one or more alicyclic epoxy rings; and, with respect to 100 parts by weight of the first epoxy compound (A),

a second epoxy compound (B) comprising one or more glycidyl ether groups in 140 parts by weight to 500 parts by weight; and

an oxetane compound (C) in 5 parts by weight to 85 parts by weight,

wherein the adhesive composition has a rate of change in the viscosity (W) of 30% or less, wherein the rate of change in the viscosity (W) is represented by the following General Formula 2:

W

=

(

V

⁢

⁢

2

-

V

⁢

⁢

1

)

2

V

⁢

⁢

1

×

100

⁢

(

%

)

[

General

⁢

⁢

Formula

⁢

⁢

2

]

in General Formula 2, V1 is initial viscosity measure after leaving the adhesive composition unattended for 100 hours at 25° C., and V2 is late viscosity (V2) measured after leaving the adhesive composition unattended for one week at 25° C.

12. The adhesive composition for a polarizing plate of claim 11 , comprising the first epoxy compound (A) in greater than or equal to 5 parts by weight and less than or equal to 45 parts by weight with respect to a total 100 parts by weight of the adhesive composition.

13. The adhesive composition for a polarizing plate of claim 11 , which has storage modulus of 700 Mpa to 1,600 Mpa at 80° C. after curing under a measurement condition of a temperature range of −30° C. to 160° C., a temperature raising rate of 5° C./min, a frequency of 1 Hz and strain of 10%.