Polyimide film and flexible display panel including the same
Provided are a polyimide-based film, a window cover film, and a display panel including the same. More particularly, a polyimide-based film having different surface properties of both surfaces is provided.
1. A polyimide-based film having different surface properties, wherein when a strength of one surface of both surfaces is 100%, a strength of the other surface is 40 to 80% of the strength of the one surface, the strength being quantified by a ratio of an aromatic ring peak intensity measured by Raman spectroscopic analysis,
wherein the polyimide-based film has a light transmittance of 5% or more as measured at 388 nm according to ASTM D1746, a total light transmittance of 87% or more as measured at 400 to 700 nm, a haze of 2.0% or less, a yellow index of 5.0 or less, and a b* value of 2.0 or less.
2. The polyimide-based film of claim 1 , wherein the polyimide-based film has a water contact angle difference of both surfaces of 5° or more and a dynamic friction coefficient difference of 0.1 μd or more.
3. The polyimide-based film of claim 1 , wherein the polyimide-based film has a modulus according to ASTM D882 of 3 GPa or more and an elongation at break according to ASTM D882 of 8% or more.
4. The polyimide-based film of claim 1 , wherein the polyimide-based film has a thickness of 10 to 500 μm.
5. The polyimide-based film of claim 1 , wherein the polyimide-based film has a polyamide-imide structure.
6. The polyimide-based film of claim 5 , wherein the polyimide-based film includes a unit derived from a fluorine-based aromatic diamine.
7. The polyimide-based film of claim 5 , wherein the polyimide-based film includes a unit derived from a cycloaliphatic dianhydride.
8. The polyimide-based film of claim 5 , wherein the polyimide-based film includes a unit derived from a fluorine-based aromatic diamine, a unit derived from an aromatic dianhydride, and a unit derived from an aromatic diacid dichloride.
9. The polyimide-based film of claim 8 , wherein the polyimide-based film further includes a unit derived from a cycloaliphatic dianhydride.
10. A window cover film comprising:
the polyimide-based film of claim 1 ; and
a coating layer formed on least one surface of the polyimide-based film.
11. The window cover film of claim 10 , wherein the coating layer is any one or more selected from an antistatic layer, an anti-fingerprint layer, an antifouling layer, an anti-scratch layer, a low-refractive layer, an antireflective layer, and shock absorption layer.
12. A flexible display panel comprising the polyimide-based film of claim 1 .