Composite cover film and flexible display device

1. A composite cover film, comprising a polyimide layer, and a first hard coating and a first transparent optical adhesive layer disposed on two sides of the polyimide layer, respectively, wherein at least one of the first hard coating and the first transparent optical adhesive layer contains a nanoscale colorant,

wherein the first hard coating is formed by curing the following components: 0.001 wt % to 40 wt % of the nanoscale colorant; 10 wt % to 20 wt % of a polymer; 0.02 wt % to 5 wt % of an adhesive; at least one additive, each having an amount of no more than 5 wt %; and a first solvent, and

wherein the first hard coating has a thickness of 15 nm to 50 μm.

2. The composite cover film according to claim 1 , further comprising a second hard coating disposed between the polyimide layer and the first transparent optical adhesive layer.

3. The composite cover film according to claim 2 , wherein the second hard coating contains the nanoscale colorant.

4. The composite cover film according to claim 2 , wherein the second hard coating is formed by curing the following components:

0.001 wt % to 40 wt % of the nanoscale colorant;

10 wt % to 20 wt % of a polymer;

0.02 wt % to 5 wt % of an adhesive;

at least one additive, each having an amount of no more than 5 wt %; and

a first solvent,

wherein the second hard coating has a thickness of 15 nm to 50 μm.

5. The composite cover film according to claim 1 , wherein the nanoscale colorant have a spectrum adjustment effect at a wave band from 400 to 750 nm.

6. The composite cover film according to claim 1 , wherein the nanoscale colorant comprises nanoscale metal structures and/or nanoscale pigments;

the nanoscale metal structures are metal nanoplates, metal nanoparticles, metal nanoribbons, metal nanowires, metal nanorods, or metal nanoprisms, and metal in the nanoscale metal structures is one or more selected from the group consisting of silver, gold, indium, tin, aluminum, titanium, iron, copper and alloys thereof; and

the nanoscale pigments are nanoscale silicon oxide, nanoscale titanium dioxide, nanoscale zinc oxide or nanoscale magnesium oxide.

7. The composite cover film according to claim 6 , wherein the nanoscale metal structures have an average particle size of no more than 100 nanometers, and the nanoscale pigments have an average particle size of 10 to 50 nm.

8. The composite cover film according to claim 6 , wherein the nanoscale metal structures are silver nanoparticles, gold-silver alloy nanoparticles, or silver nanotubes.

9. The composite cover film according to claim 1 , wherein the first transparent optical adhesive layer comprises an optical adhesive layer which is formed by curing the following components:

1 to 20 parts by weight of the nanoscale colorant;

60 to 80 parts by weight of an optical adhesive;

at least one additive, each having an amount of 0.1 to 2 parts by weight; and

20 to 40 parts by weight of a second solvent.

10. The composite cover film according to claim 1 , wherein the first transparent optical adhesive layer comprises a heavy release film, an optical adhesive layer and a light release adhesive film disposed in order;

the light release adhesive film has a thickness of 25 μm to 75 μm and a releasing force of 2 to 20 g/f; and

the heavy release film has a thickness of 50 μm to 125 μm and a releasing force of 30 to 100 g/f.

11. A flexible display device, comprising a flexible display panel and the composite cover film according to claim 1 disposed at a light-exiting side of the flexible display panel.

12. The flexible display device according to claim 11 , wherein the composite cover film further comprises a second hard coating disposed between the polyimide layer and the first transparent optical adhesive layer.

13. The flexible display device according to claim 11 , further comprising a second transparent optical adhesive layer, a touch screen and a polarizing layer, wherein the flexible display panel, the second transparent optical adhesive layer, the touch screen, the polarizing layer and the composite cover film are disposed in order, and the second transparent optical adhesive layer contains the nanoscale colorant, wherein the nanoscale colorant comprises nanoscale metal structures and/or nanoscale pigments;

the nanoscale metal structures are metal nanoplates, metal nanoparticles, metal nanoribbons, metal nanowires, metal nanorods, or metal nanoprisms, and metal in the nanoscale metal structures is one or more selected from the group consisting of silver, gold, indium, tin, aluminum, titanium, iron, copper and alloys thereof; and

the nanoscale pigments are nanoscale silicon oxide, nanoscale titanium dioxide, nanoscale zinc oxide or nanoscale magnesium oxide.

14. The flexible display device according to claim 13 , wherein the composite cover film further comprises a second hard coating disposed between the polyimide layer and the first transparent optical adhesive layer.

15. The flexible display device according to claim 13 , wherein the second transparent optical adhesive layer comprises an optical adhesive layer which is formed by curing the following components:

1 to 20 parts by weight of the nanoscale colorant;

60 to 80 parts by weight of an optical adhesive;

at least one additive, each having an amount of 0.1 to 2 parts by weight; and

20 to 40 parts by weight of a third solvent.

16. A method for manufacturing the flexible display device according to claim 11 , comprising:

providing the flexible display panel;

forming a second transparent optical adhesive layer on a surface at the light-exiting side of the flexible display panel;

sequentially forming a touch screen and a polarizing layer on the second transparent optical adhesive layer; and

forming the first hard coating at one side of the polyimide layer, and a first transparent optical adhesive layer at the other side of the polyimide layer, and bonding the polyimide layer and the polarizing layer together through the first transparent optical adhesive layer to obtain the flexible display device,

and

the second transparent optical adhesive layer contains or does not contain the nanoscale colorant.

17. A method for manufacturing the flexible display device according to claim 11 , comprising:

providing the flexible display panel;

forming a second transparent optical adhesive layer on a surface at the light-exiting side of the flexible display panel;

sequentially forming a touch screen and a polarizing layer on the second transparent optical adhesive layer; and

forming the first hard coating and a second hard coating at the two sides of the polyimide layer, respectively, forming the first transparent optical adhesive layer at a side of the second hard coating away from the polyimide layer, and bonding the second hard coating and the polarizing layer together through the first transparent optical adhesive layer to obtain the flexible display device,

wherein the second transparent optical adhesive layer contains or does not contain the nanoscale colorant.

18. A composite cover film, comprising a polyimide layer, and a first hard coating and a first transparent optical adhesive layer disposed on two sides of the polyimide layer, respectively, wherein at least one of the first hard coating and the first transparent optical adhesive layer contains a nanoscale colorant, wherein the composite cover film further comprising a second hard coating disposed between the polyimide layer and the first transparent optical adhesive layer, wherein the second hard coating is formed by curing the following components:

0.001 wt % to 40 wt % of the nanoscale colorant;

10 wt % to 20 wt % of a polymer;

0.02 wt % to 5 wt % of an adhesive;

at least one additive, each having an amount of no more than 5 wt %; and

a first solvent,

wherein the second hard coating has a thickness of 15 nm to 50 μm.

19. A composite cover film, comprising a polyimide layer, and a first hard coating and a first transparent optical adhesive layer disposed on two sides of the polyimide layer, respectively, wherein at least one of the first hard coating and the first transparent optical adhesive layer contains a nanoscale colorant, wherein the first transparent optical adhesive layer comprises an optical adhesive layer which is formed by curing the following components:

1 to 20 parts by weight of the nanoscale colorant;

60 to 80 parts by weight of an optical adhesive;

at least one additive, each having an amount of 0.1 to 2 parts by weight; and

20 to 40 parts by weight of a solvent.