Composition for window film, flexible window film formed therefrom, and flexible display device comprising same

1. A composition for window films, comprising: a siloxane resin represented by Chemical Formula 1; and an iodonium ion-containing photocationic initiator:

(R 1 SiO 3/2 ) x (R 2 R 3 SiO 2/2 ) y   <Chemical Formula 1>

wherein in Chemical Formula 1, R 1 is a crosslinkable functional group; R 2 and R 3 are each independently hydrogen, a crosslinkable group, an unsubstituted or substituted C 1 to C 20 alkyl group, or an unsubstituted or substituted C 5 to C 20 cycloalkyl group, at least one of R 2 and R 3 being an unsubstituted or substituted C 1 to C 20 alkyl group; and 0<x≤1, 0≤y<1, and x+y=1, and

wherein the siloxane resin represented by Chemical Formula 1 has a weight average molecular weight of 4,500 to 100,000.

2. The composition for window films according to claim 1 , wherein the iodonium ion-containing photocationic initiator is present in an amount of about 1 part by weight to about 15 parts by weight relative 100 parts by weight of the siloxane resin.

3. The composition for window films according to claim 1 , wherein the iodonium ion-containing photocationic initiator comprises one diaryliodonium selected from diphenyliodonium, 4-methoxydiphenyliodonium, bis(4-methylphenyl)iodonium, bis(4-tert-butylphenyl)iodonium, bis(4-dodecylphenyl)iodonium, and (4-methylphenyl)[4-(2-methylpropyl)phenyl]iodonium, and one anion selected from hexafluorophosphate, tetrafluoroborate, tetrakis(pentafluorophenyl)borate, hexafluoroantimonate, hexafluoroarsenate, hexachloroantimonate, nitrate, para-toluenesulfonate, 9,10-dimethoxyanthracene-2-sulfonate, triflate, and perfluoro-1-butanesulfonate.

4. The composition for window films according to claim 3 , wherein the iodonium ion-containing photocationic initiator comprises at least one selected from diphenyliodonium hexafluorophosphate,-(4-methylphenyl)[4-(2-methylpropyl)phenyl]iodonium hexafluorophosphate, and bis(4-tert-butylphenyl)iodonium tetrakis(pentafluorophenyl)borate.

5. The composition for window films according to claim 1 , wherein the siloxane resin comprises at least one of compounds represented by Chemical Formula 1-1 to 1-13:

(EcSiO 3/2 ) x (EcMeSiO 2/2 ) y   <Chemical Formula 1-1>

(EcSiO 3/2 ) x ((Me) 2 SiO 2/2 ) y   <Chemical Formula 1-2>

(EcSiO 3/2 ) x (MeEtSiO 2/2 ) y   <Chemical Formula 1-3>

(EcSiO 3/2 ) x (GpMeSiO 2/2 ) y   <Chemical Formula 1-4>

(GpSiO 3/2 ) x (EcMeSiO 2/2 ) y   <Chemical Formula 1-5>

(GpSiO 3/2 ) x ((Me) 2 SiO 2/2 ) y   <Chemical Formula 1-6>

(GpSiO 3/2 ) x (MeEtSiO 2/2 ) y   <Chemical Formula 1-7>

(GpSiO 3/2 ) x (GpMeSiO 2/2 ) y   <Chemical Formula 1-8>

(OpSiO 3/2 ) x (EcMeSiO 2/2 ) y   <Chemical Formula 1-9>

(OpSiO 3/2 ) x ((Me) 2 SiO 2/2 ) y   <Chemical Formula 1-10>

(OpSiO 3/2 ) x (MeEtSiO 2/2 ) y   <Chemical Formula 1-11>

(OpSiO 3/2 ) x (GpMeSiO 2/2 ) y   <Chemical Formula 1-12>

wherein in Chemical Formula 1-1 to 1-12, Ec is a (3,4-epoxycyclohexyl)ethyl group, Me is a methyl group, Et is an ethyl group, Gp is a 3-glycidoxypropyl group, Op is a 3-oxetanylpropyl group, and 0<x<1, 0<y<1, and x+y=1,

(EcSiO 3/2 ) x1 (GpSiO 3/2 ) x2   <Chemical Formula 1-13>

wherein in Chemical Formula 1-13, Ec is a (3,4-epoxycyclohexyl)ethyl group, Gp is a 3-glycidoxypropyl group, and 0<x1<1, 0<x2<1, and x1+x2=1.

6. The composition for window films according to claim 1 , further comprising: a crosslinking agent.

7. The composition for window films according to claim 6 , wherein the crosslinking agent comprises at least one of a non-cyclic aliphatic epoxy monomer, a cyclic aliphatic epoxy monomer, an aromatic epoxy monomer, and a hydrogenated aromatic epoxy monomer.

8. A flexible window film comprising a base layer and a coating layer formed on one surface of the base layer, wherein the coating layer comprises an iodonium ion-containing photocationic initiator,

wherein the coating layer is formed from a composition for window films, comprising: a siloxane resin represented by Chemical Formula 1 and the iodonium ion-containing photocationic initiator:

(R 1 SiO 3/2 ) x (R 2 R 3 SiO 2/2 ) y   <Chemical Formula 1>

wherein in Chemical Formula 1, R 1 is a crosslinkable functional group; R 2 and R 3 are each independently hydrogen, a crosslinkable group, an unsubstituted or substituted C 1 to C 20 alkyl group, or an unsubstituted or substituted C 5 to C 20 cycloalkyl group, at least one of R 2 and R 3 being an unsubstituted or substituted C 1 to C 20 alkyl group; and 0<x≤1, 0≤y<1, and x+y=1,

wherein the siloxane resin represented by Chemical Formula 1 has a weight average molecular weight of 4,500 to 100,000 and

wherein the iodonium ion-containing photocationic initiator comprises:

at least one diaryliodonium selected from 4-methoxydiphenyliodonium, bis(4-methylphenyl)iodonium, bis(4-tert-butylphenyl)iodonium, bis(4-dodecylphenyl)iodonium, and (4-methylphenyl)[4-(2-methylpropyl)phenyl]iodonium, and at least one anion selected from hexafluorophosphate, tetrafluoroborate, tetrakis(pentafluorophenyl)borate, hexafluoroantimonate, hexafluoroarsenate, hexachloroantimonate, nitrate, para-toluenesulfonate, 9,10-dimethoxyanthracene-2-sulfonate, triflate, and perfluoro-1-butanesulfonate; or

diphenyliodonium and at least one anion selected from tetrafluoroborate, tetrakis(pentafluorophenyl)borate, hexafluoroarsenate, hexachloroantimonate, nitrate, para-toluenesulfonate, 9,10-dimethoxyanthracene-2-sulfonate, triflate, and perfluoro-1-butanesulfonate.

9. The flexible window film according to claim 8 , further comprising: an adhesive layer formed on the other surface of the base layer.

10. The flexible window film according to claim 8 , wherein the flexible window film has a ΔY.I of about 1.0 or less.

11. A flexible display comprising the flexible window film according to claim 8 .

12. The flexible display according to claim 11 , wherein the flexible display comprises a display part, an adhesive layer formed on the display part, a polarizing plate formed on the adhesive layer, a touchscreen panel formed on the polarizing plate, and the flexible window film formed on the touchscreen panel.

13. The flexible display according to claim 11 , wherein the flexible display comprises a display part, a touchscreen panel formed on the display part, a polarizing plate formed on the touchscreen panel and the flexible window film formed on the polarizing plate.

14. The flexible display according to claim 11 , wherein the flexible display comprises a display part, an adhesive layer formed on the display part and the flexible window film formed on the adhesive layer.

15. The flexible display according to claim 14 , wherein the display part further comprises a polarizing plate disposed at an upper or lower side thereof.