Polyimide substrate and method for preparing the same, and flexible display

Abstract

The present invention relates to the field of displays and discloses a polyimide substrate, which is manufactured by reacting lignin, polyimide and a free radical initiator. Because lignin contains various active groups, for example, hydroxyl, carboxyl and aryl, etc., when it is introduced into the polymer structure of polyimide, the maximum absorption peak of the polymer can be made to redshift from less than or equal to 280 nm to less than or equal to 380 nm, so that a certain absorption and screening action may be laid on the light wave during a subsequent Laser Lift Off process, and the substrate and the liquid crystal may be prevented from being damaged during a Laser Lift Off process of the glass base substrate, thereby guaranteeing the display quality of the flexible display.

Claims

1. A method for preparing a polyimide substrate, comprising the steps of: dissolving lignin, polyimide, and a free radical polymerization initiator in an organic solvent; and coating the solution obtained after dissolution on a glass substrate, and obtaining a polyimide substrate by reacting in a nitrogen gas atmosphere, wherein the polyimide substrate comprises active groups of hydroxyl, carboxyl, and aryl from the lignin such that the polyimide substrate has a maximum absorption peak that redshifts from less than or equal to 280 nm to less than or equal to 380 nm.

2. The preparation method according to claim 1, wherein, a mass ratio of lignin, polyimide and the free radical polymerization initiator is 100:300-1000:2.

3. The preparation method according to claim 2, wherein, the organic solvent is N-methylpyrrolidone, tetrahydrofuran or toluene.

4. The preparation method according to claim 3, wherein, the free radical polymerization initiator is benzoyl peroxide, t-butyl peroxybenzoate or methylethyl ketone peroxide.

5. The preparation method according to claim 1, wherein, the reaction is conducted at a temperature of 200-400 C.

6. The preparation method according to claim 1, wherein, the reaction is maintained for 6-24 hours.

7. A polyimide substrate, manufactured by reacting lignin, polyimide, and a free radical polymerization initiator, wherein the polyimide substrate comprises active groups of hydroxyl, carboxyl, and aryl from the lignin such that the polyimide substrate has a maximum absorption peak that redshifts from less than or equal to 280 nm to less than or equal to 380 nm.

8. The polyimide substrate according to claim 7, wherein, a mass ratio of lignin, polyimide and the free radical polymerization initiator is 100:300-1000:2.

9. The polyimide substrate according to claim 7, wherein, the free radical polymerization initiator is benzoyl peroxide, t-butyl peroxybenzoate or methylethyl ketone peroxide.

10. The polyimide substrate according to claim 7, wherein the polyimide substrate has a maximum absorption peak that redshifts from less than or equal to 280 nm to greater than 280 nm.

11. The polyimide substrate according to claim 7, wherein the polyimide substrate has a transmittance above 85%.

12. A flexible display, comprising the polyimide substrate according to claim 7.

13. The flexible display according to claim 12, wherein, a mass ratio of lignin, polyimide and the free radical polymerization initiator is 100:300-1000:2.

14. The flexible display according to claim 12, wherein, the free radical polymerization initiator is benzoyl peroxide, t-butyl peroxybenzoate or methylethyl ketone peroxide.

15. A flexible display, comprising a polyimide substrate prepared by a method comprising the steps of: dissolving lignin, polyimide, and a free radical polymerization initiator in an organic solvent; and coating the solution obtained after dissolution on a glass substrate, and obtaining a polyimide substrate by reacting in a nitrogen gas atmosphere, wherein the polyimide substrate comprises active groups of hydroxyl, carboxyl, and aryl from the lignin such that the polyimide substrate has a maximum absorption peak that redshifts from less than or equal to 280 nm to less than or equal to 380 nm.

16. The flexible display according to claim 15, wherein, a mass ratio of lignin, polyimide and the free radical polymerization initiator is 100:300-1000:2.

17. The flexible display according to claim 16, wherein, the organic solvent is N-methylpyrrolidone, tetrahydrofuran or toluene.

18. The flexible display according to claim 17, wherein, the free radical polymerization initiator is benzoyl peroxide, t-butyl peroxybenzoate or methylethyl ketone peroxide.

19. The flexible display according to claim 15, wherein, the reaction is conducted at a temperature of 200-400 C.

20. The flexible display according to claim 15, wherein, the reaction is maintained for 6-24 hours.

Description

BRIEF DESCRIPTION

(1) FIG. 1 shows a flexible display with a glass base substrate unpeeled; wherein, 1 represents a glass base substrate, and 2 represents a polyimide substrate;

(2) FIG. 2 shows the light transmittance of a polyimide substrate according to one embodiment of the invention.

DETAILED DESCRIPTION

(3) For further understanding the invention, optional implementations of the invention will be described below in conjunction with the embodiments; however, it should be understood that these descriptions are only used for further illustrating the characteristics and advantages of the invention, rather than limiting the claims of the invention.

(4) One embodiment of the invention discloses a method for preparing a polyimide substrate, which includes the steps of:

(5) dissolving lignin, polyimide and a free radical polymerization initiator in an organic solvent, coating the solution obtained on a glass substrate, and obtaining a polyimide substrate by reacting in a nitrogen gas atmosphere.

(6) The lignin contains a large amount of active groups, for example, hydroxyl, carboxyl, carbonyl, aryl, etc., which may influence the absorption of ultraviolet light by lignin. In the invention, the maximum absorption peak of a polymer, which is formed by introducing lignin with such groups into polyimide, redshifts from less than or equal to 280 nm to less than or equal to 380 nm.

(7) During the preparation of a flexible display, the wavelength for sealing and curing is about 360 nm, and the wavelength for the LLO process is about 308 nm. In the invention, the maximum absorption peak of the polyimide substrate into which lignin is introduced may reach 380 nm, thus the light waves during sealing and curing or the LLO process may be totally absorbed, thereby the damage of the light waves on the substrate and the liquid crystals may be avoided.

(8) According to one embodiment of the invention, lignin, polyimide and a free radical polymerization initiator are dissolved in an organic solvent, the solution obtained is coated on a glass substrate, and a polyimide substrate is obtained by reacting in a nitrogen gas atmosphere. A mass ratio of lignin, polyimide and the free radical polymerization initiator may be 100:300-1000:2, or it may be 100:400-900:2, and it may also be 100:450-650:2.

(9) The organic solvent may be NMP, tetrahydrofuran or toluene. The free radical polymerization initiator may be benzoyl peroxide, t-butyl peroxybenzoate or methylethyl ketone peroxide.

(10) The reaction may be conducted at a temperature of 200-400 C., or at a temperature of 200-250 C.

(11) The reaction may be maintained for 6-24 hours, or for 6-8 hours.

(12) The invention further discloses a polyimide substrate, which is manufactured by reacting lignin, polyimide and a free radical initiator. A mass ratio of lignin, polyimide and the free radical polymerization initiator may be 100:300-1000:2, or it may be 100:400-900:2, and it may also be 100:450-650:2. The reaction may be conducted at a temperature of 200-400 C., or at a temperature of 200-250 C. The reaction may be maintained for 6-24 hours, or for 6-8 hours.

(13) The invention further discloses a flexible display, which includes the polyimide substrate according to the above embodiments or a polyimide substrate prepared by the method according to the above embodiments. In the invention, the method for preparing a flexible display by a polyimide substrate is not specifically limited, and well-known methods to one skilled in the art may be employed.

(14) For further understanding the invention, a polyimide substrate and a method for preparing the same and a flexible display device of the invention will be illustrated in detail below in conjunction with the embodiments, and the protection scope of the invention is not limited to the embodiments below.

(15) The lignin employed in the invention is a commercially available product.

(16) Embodiment 1

(17) 100 g lignin, 450 g polyimide and 2 g benzoyl peroxide are dissolved in NMP, and after a homogeneous solution is formed, the solution is coated on a glass base substrate by a coating equipment, and at the same time, a nitrogen gas is fed into the equipment to remove the oxygen gas, and it reacts for 6 hours at 200 C., thus a polyimide substrate is obtained.

(18) The light absorption performance and the transparency of the polyimide substrate obtained are tested, and reference may be made to FIG. 2 for the test results. FIG. 2 shows the light transmittance of the polyimide substrate according to this embodiment. It may be known from FIG. 2 that, in comparison with an ordinary undoped polyimide substrate, the maximum absorption peak of the polyimide substrate according to this embodiment, which is modified by lignin, redshifts from less than or equal to 280 nm to less than or equal to 380 nm. Moreover, it has high transparency, and the transmittance may reach above 85% in the range of visible lights.

(19) Embodiment 2

(20) 100 g lignin, 500 g polyimide and 2 g benzoyl peroxide are dissolved in tetrahydrofuran, and after a homogeneous solution is formed, the solution is coated on a glass base substrate by a coating equipment, and at the same time, a nitrogen gas is fed into the equipment to remove the oxygen gas, and it reacts for 8 hours at 250 C., thus a polyimide substrate is obtained.

(21) The light absorption performance and the transparency of the polyimide substrate obtained are tested, and results similar to Embodiment 1 are obtained, that is, in comparison with an ordinary undoped polyimide substrate, the maximum absorption peak of the polyimide substrate according to this embodiment, which is modified by lignin, redshifts from less than or equal to 280 nm to less than or equal to 380 nm.

(22) Embodiment 3

(23) 100 g lignin, 800 g polyimide and 2 g benzoyl peroxide are dissolved in toluene, and after a homogeneous solution is formed, the solution is coated on a glass base substrate by a coating equipment, and at the same time, a nitrogen gas is fed into the equipment to remove the oxygen gas, and it reacts for 24 hours at 300 C., thus a polyimide substrate is obtained.

(24) The light absorption performance and the transparency of the polyimide substrate obtained are tested, and results similar to Embodiment 1 are obtained, that is, in comparison with an ordinary undoped polyimide substrate, the maximum absorption peak of the polyimide substrate according to this embodiment, which is modified by lignin, redshifts from less than or equal to 280 nm to less than or equal to 380 nm.

(25) The above embodiments are only illustrated for aiding the understanding of the method of the invention and its core concept. It should be pointed out that, for one of ordinary skills in the art, various improvements and modifications may be made to the invention without departing from the principles of the invention, and these improvements and modifications also fall into the protection scope of the claims of the invention.

(26) With the above illustration of the embodiments disclosed, those skilled in the art can implement or utilize the invention. Various modifications to these embodiments are apparent to those skilled in the art, and the general principle defined herein may be realized in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention will not be limited to the embodiments illustrated; instead, the invention conforms to the widest range consistent with the principles and novel features disclosed herein.