Flexible film structure, method of manufacturing the same, and flexible display device including the same

1. A flexible display device, comprising:

a flexible display panel configured to display an image on at least one surface thereof; and

a window cover on the at least one surface of the flexible display panel,

wherein the window cover includes a flexible film structure, the flexible film structure including a base film, at least one first functional hard coating layer on a first side the base film, and a lower functional hard coating layer on a second side of the base film, the second side of the base film being opposite to the first side of the base film,

wherein the at least one first functional hard coating layer includes a siloxane polymer having an epoxy group,

wherein the lower functional hard coating layer includes a siloxane polymer having an epoxy group,

wherein the flexible film structure has a thickness of about 100 μm or less and a transmissivity of about 90% to 92% for light having a wavelength of about 450 nm to 700 nm, and

wherein the flexible film structure further includes a barrier layer on the at least one first functional hard coating layer and a second functional hard coating layer on the barrier layer, the second functional hard coating layer including a siloxane polymer having an epoxy group.

2. The flexible display device as claimed in claim 1 , wherein the base film includes a glass film, a plastic film, or a metal film.

3. The flexible display device as claimed in claim 1 , wherein:

a weight-average molecular weight of each siloxane polymer is about 1,500 g/mole to 2,100 g/mole, and

a number-average molecular weight of each siloxane polymer is about 1,300 g/mole to 1,700 g/mole.

4. The flexible display device as claimed in claim 1 , wherein the flexible film structure further includes a transmissivity enhancement layer on the at least one first functional hard coating layer.

5. The flexible display device as claimed in claim 1 . further comprising an adhesive layer between the window cover and the flexible display panel, the adhesive layer adhering the window cover with the flexible display panel.

6. The flexible display device as claimed in claim 1 , wherein the flexible film structure further includes a transparent electrode layer on the second functional hard coating layer.

7. The flexible display device as claimed in claim 1 , wherein the flexible display panel includes:

at least one thin film transistor on a foldable substrate;

an insulating layer covering the at least one thin film transistor;

an organic light-emitting device on the insulating layer and electrically connected to the thin film transistor, the organic light-emitting device being configured to emit light from an organic emission layer between electrodes thereof; and

an encapsulation layer on the foldable substrate, the encapsulation layer sealing the organic light-emitting device.

8. The flexible display device as claimed in claim 7 , further comprising:

a touch screen panel adhered to the encapsulation layer with an adhesive, the touch screen panel being foldable and configured to sense a touch input from the at least one first functional hard coating layer; and

an optical film adhered to the touch screen panel with an adhesive, the optical film being configured to prevent reflection of external light.

9. A flexible display device, comprising:

a flexible display panel that displays an image on at least one surface thereof; and

a window cover on the at least one surface of the flexible display panel,

wherein the window cover includes a flexible film structure, the flexible film structure including a base film, a first functional hard coating layer on one side the base film, and a second functional hard coating layer on the other side of the base film, the other side of the base film being opposite to the one side of the base film,

wherein the first functional hard coating layer includes a siloxane polymer that is crosslinked via an epoxy group,

wherein the second functional hard coating layer includes a siloxane polymer that is crosslinked via an epoxy group,

wherein the flexible film structure has a thickness of about 100 μm or less and a transmissivity of about 90% to 92% for light having a wavelength of about 450 nm to 700 nm, and

wherein the flexible film structure further includes:

a barrier layer on the first functional hard coating layer, and

a third functional hard coating layer on the barrier layer, the third functional hard coating layer including a siloxane polymer that is crosslinked via an epoxy group.

10. The flexible display device as claimed in claim 9 , wherein:

a weight-average molecular weight of each siloxane polymer is about 1,500 g/mole to 2,100 g/mole, and

a number-average molecular weight of each siloxane polymer is about 1,300 g/mole to 1,700 g/mole.

11. The flexible display device as claimed in claim 9 , wherein the flexible film structure further includes a transparent electrode layer on the third functional hard coating layer.

12. The flexible display device as claimed in claim 9 , wherein the flexible display device is foldable about at least one axis such that a display area of flexible display panel faces an interior of the flexible display device.

13. The flexible display device as claimed in claim 12 , wherein the flexible display panel includes a sensor such that display of an image by the flexible display panel is stopped when the flexible display device is folded such that the display area of flexible display panel faces the interior of the flexible display device.

14. The flexible display device as claimed in claim 9 , wherein the base film includes a glass film, a plastic film, or a metal film.

15. The flexible display device as claimed in claim 9 , wherein the flexible film structure further includes a transmissivity enhancement layer on the first functional hard coating layer.

16. The flexible display device as claimed in claim 9 , further comprising an adhesive layer between the window cover and the flexible display panel, the adhesive layer adhering the window cover with the flexible display panel.