Composition for polarizing film, polarizing film, and display device

1. A composition for a polarizing film, comprising:

a polymer and

at least one dichroic dye uniformly dispersed in the polymer,

wherein the polymer is a polyolefin, a polyamide, a polyester, a polyacrylate, a polystyrene, a copolymer thereof, or a combination thereof, having a haze of less than or equal to 2%, and a solubility parameter of 15 to 18,

wherein the dichroic dye comprises a first dichroic dye represented by Chemical Formula 1 and having a molecular weight of about 600 Daltons to about 1,000 Daltons and a solubility parameter of less than or equal to 20.9:

wherein, in Chemical Formula 1,

Ar 1 to Ar 3 are each independently a substituted or unsubstituted phenylene group,

R 1 is a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, a substituted or unsubstituted C1 to C20 alkylthio group, or a combination thereof,

R 2 is hydrogen, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C20 aryl group, a C1 to C20 alkoxy group, a substituted or unsubstituted C1 to C20 alkylthio group, —NR 3 R 4 , or a combination thereof, wherein R 3 and R 4 are each independently hydrogen or a substituted or unsubstituted C1 to C10 alkyl group, and wherein R 3 and R 4 are optionally linked to each other to form a ring, and

n is 0 or 1, and

m is 0,

wherein a solubility parameter difference between the polymer and the dichroic dye is less than 7.2, and

wherein a 30 μm-thick film formed from the composition, has a color shift (Δa*b*) of less than 2 upon standing at 85° C. for 250 hours.

2. The composition for a polarizing film of claim 1 , wherein

R 1 in Chemical Formula 1 is a substituted or unsubstituted C4 to C20 alkyl group or a substituted or unsubstituted C4 to C20 alkoxy group, and

R 2 in Chemical Formula 1 is hydrogen, a substituted or unsubstituted C1 to C20 alkyl group, —NR 3 R 4 , or a combination thereof, wherein R 3 and R 4 are each independently hydrogen or a substituted or unsubstituted C1 to C10 alkyl group, and wherein R 3 and R 4 are optionally linked to each other to form a ring.

3. The composition for a polarizing film of claim 1 , wherein the first dichroic dye has a maximum absorption wavelength λ max of about 380 nanometers to about 490 nanometers.

4. The composition for a polarizing film of claim 1 , wherein the dichroic dye further comprises a second dichroic dye having a maximum absorption wavelength λ max of greater than about 490 nanometers and less than or equal to about 580 nanometers, a third dichroic dye having a maximum absorption wavelength λ max of greater than about 580 nanometers and less than or equal to about 780 nanometers, or a combination thereof.

5. The composition for a polarizing film of claim 1 , wherein the polymer comprises polyethylene, polypropylene, polyethylene terephthalate, polyethylene terephthalate glycol, polyethylene naphthalate, nylon, a copolymer thereof, or a combination thereof.

6. The composition for a polarizing film of claim 1 , wherein an amount of the dichroic dye is about 0.01 to 5 parts by weight based on 100 parts by weight of the polymer.

7. A polarizing film comprising:

a polymer and

at least one dichroic dye uniformly dispersed in the polymer,

wherein the polymer is a polyolefin, a polyamide, a polyester, a polyacrylate, a polystyrene, a copolymer thereof, or a combination thereof, having a haze of less than or equal to 2%, and a solubility parameter of 15 to 18,

wherein the dichroic dye comprises a first dichroic dye represented by Chemical Formula 1 and having a molecular weight of about 600 Daltons to about 1,000 Daltons and a solubility parameter of less than or equal to 20.9:

wherein, in Chemical Formula 1,

Ar 1 to Ar 3 are each independently a substituted or unsubstituted phenylene group,

R 1 is a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, a substituted or unsubstituted C1 to C20 alkylthio group, or a combination thereof,

R 2 is hydrogen, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C20 aryl group, a C1 to C20 alkoxy group, a substituted or unsubstituted C1 to C20 alkylthio group, —NR 3 R 4 , or a combination thereof, wherein R 3 and R 4 are each independently hydrogen or a substituted or unsubstituted C1 to C10 alkyl group, and wherein R 3 and R 4 are optionally linked to each other to form a ring, and

n is 0 or 1, and

m is 0,

wherein a solubility parameter difference between the polymer and the dichroic dye is less than 7.2, and

wherein a color shift (Δa*b*) of the polarizing film is less than 2 upon standing at 85° C. for 250 hours, for a film thickness of 30 μm.

8. The polarizing film of claim 7 , wherein R 1 in Chemical Formula 1 is a substituted or unsubstituted C4 to C20 alkyl group or a substituted or unsubstituted C4 to C20 alkoxy group, and

R 2 in Chemical Formula 1 is hydrogen, a substituted or unsubstituted C1 to C20 alkyl group, —NR 3 R 4 , or a combination thereof, wherein R 3 and R 4 are each independently hydrogen or a substituted or unsubstituted C1 to C10 alkyl group, and wherein R 3 and R 4 are optionally linked to each other to form a ring.

9. The polarizing film of claim 7 , wherein the first dichroic dye has a maximum absorption wavelength λ max of about 380 nanometers to about 490 nanometers.

10. The polarizing film of claim 7 , wherein the dichroic dye further comprises a second dichroic dye having a maximum absorption wavelength λ max of greater than about 490 nanometers and less than or equal to about 580 nanometers, a third dichroic dye having a maximum absorption wavelength λ max of greater than about 580 nanometers and less than or equal to about 780 nanometers, or a combination thereof.

11. The polarizing film of claim 7 , wherein the polymer comprises polyethylene, polypropylene, polyethylene terephthalate, polyethylene terephthalate glycol, polyethylene naphthalate, nylon, a copolymer thereof, or a combination thereof.

12. The polarizing film of claim 7 , wherein

the polarizing film is a melt-blend of the polymer and the dichroic dye, and

an amount of the dichroic dye is about 0.01 to 5 parts by weight based on 100 parts by weight of the polymer.

13. A display device comprising:

a display panel and

a polarizing film of claim 7 disposed on at least one side of the display panel.

14. The display device of claim 13 , wherein the display panel is a liquid crystal panel or an organic light emitting panel.