Cover window for flexible display device and flexible display device

Patent metadata

Field	Value
Publication number	US-11958987-B2
Application number	US-201915734971-A
Country	US
Kind code	B2
Filing date	Oct 25, 2019
Priority date	Oct 26, 2018
Publication date	Apr 16, 2024
Grant date	Apr 16, 2024

Abstract

The present disclosure relates to a cover window for a flexible display device including a polymer substrate including a polyamide resin; and a hard coating layer formed on at least one surface of the polymer substrate, wherein a yellow index of the polymer substrate measured in accordance with STM E 313 is 4.00 or less, and an elastic modulus of the polymer substrate measured at a strain rate of 12.5 mm/min in accordance with ISO 527-3 is 4 to 9 GPa.

First claim

The invention claimed is:

1. A cover window for a flexible display device, comprising a polymer substrate comprising a polyamide resin; and a hard coating layer formed on at least one surface of the polymer substrate,
wherein the polyamide resin comprises a first polyamide segment and a second polyamide segment, each polymide segment containing a benzene-1,3-dicarbonyl group and a benzene-1,4-dicarbonyl group in a different molar ratio,
the polymer substrate has a yellow index of 4.00 or less as measured in accordance with STM E 313, and
an elastic modulus of 4 to 9 GPa as measured at a strain rate of 12.5 mm/min in accordance with ISO 527-3.

2. The cover window for a flexible display device of claim 1 ,
wherein no crack occurs on the cover when the cover window is wound on a mandrel having a diameter of 3 mm.

3. The cover window for a flexible display device of claim 1 ,
wherein the hard coating layer has a pencil hardness of at least 5H under a load of 750 g.

4. The cover window for a flexible display device of claim 1 ,
wherein the cover window has a transmittance of at least 90.0% with respect to light having a wavelength of 550 nm and a haze of 0.6% or less.

5. The cover window for a flexible display device of claim 1 ,
wherein the cover window has a yellow index of 3.0 or less.

6. The cover window for a flexible display device of claim 1 ,
wherein the polyamide resin is a polyamide block copolymer comprising
A) an amide bond between an aromatic diamino group and a benzene-dicarbonyl group; and
B) b1) the first polyamide segment comprising 20 mol % or less of the benzene-1,3-dicarbonyl group based on a total of the benzene-1,3-dicarbonyl group and the benzene-1,4-dicarbonyl group, and b2) the second polyamide segment comprising more than 20 mol % of the benzene-1,3-dicarbonyl group based on a total of the benzene-1,3-dicarbonyl group and the benzene-1,4-dicarbonyl group.

7. The cover window for a flexible display device of claim 6 ,
wherein a molar ratio of the first polyamide segment to the second polyamide segment is 1:0.5 to 1:10.

8. The cover window for a flexible display device of claim 6 ,
wherein the polymide block copolymer comprises the benzene dicarbonyl group of a total of 5 to 25 mol % based on a total of the benzene-1,3-dicarbonyl group and the benzene-1,4-dicarbonyl group.

9. The cover window for a flexible display device of claim 6 ,
wherein the first polyamide segment has 2 mol % or more and 20 mol % or less of the benzene-1,3-dicarbonyl group based on a total of the benzene-1,3-dicarbonyl group and the benzene-1,4-dicarbonyl group contained in the first polymide segment.

10. The cover window for a flexible display device of claim 6 ,
wherein the second polyamide segment has a ratio of isophthaloyl chloride to a total of the benzene-1,3-dicarbonyl group and the benzene-1,4-dicarbonyl group of more than 20 mol % and 40 mol % or less.

11. The cover window for a flexible display device of claim 6 ,
wherein the aromatic diamino group has a diamino group derived from at least one selected from the group consisting of 2,2′-bis(trifluoromethyl)-4,4′-biphenyldiamine, 2,2′-dimethyl-4,4′-diaminobenzidine, 4,4′-diaminodiphenyl sulfone, 4,4′-(9-fluorenylidene)dianiline, bis(4-(4-aminophenoxy)phenyl)sulfone, 2,2′,5,5′-tetrachlorobenzidine, 2,7-diaminofluorene, 4,4-diaminooctafluorobiphenyl, m-phenylenediamine, p-phenylenediamine, 4,4′-oxydianiline, 2,2′-dimethyl-4,4′-diaminobiphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,3-bis(4-aminophenoxy)benzene, and 4,4′-diaminobenzanilide.

12. The cover window for a flexible display device of claim 6 ,
wherein the polyamide block copolymer has a weight average molecular weight of 10,000 to 700,000 g/mol.

13. The cover window for a flexible display device of claim 1 ,
wherein the polymer substrate has an elongation of at least 10% as measured in accordance with ISO 527-3.

14. The cover window for a flexible display device of claim 1 ,
wherein the polymer substrate has a thickness of 5 to 300 μm.

15. The cover window for a flexible display device of claim 1 ,
wherein the hard coating layer comprises a binder resin and inorganic nanoparticles, and has a thickness of 5 μm to 50 μm.

16. A flexible display device, comprising the cover window for a flexible display device of claim 1 .

Assignees

• Lg Chemical Ltd

Inventors

• Park Jin Young
• Ryu Bi Oh
• Tae Young Ji
• Park Youngseok
• Heo Yongjoon
• Chang Yeongrae

Classifications

• H10K59/871

  Self-supporting sealing arrangements · CPC title

• C09D177/06 Primary

  Polyamides derived from polyamines and polycarboxylic acids (C09D177/10 takes precedence) · CPC title

• C08G69/32 Primary

  from aromatic diamines and aromatic dicarboxylic acids with both amino and carboxylic groups aromatically bound · CPC title

• B32B27/308

  comprising acrylic (co)polymers · CPC title

• B32B27/34

  comprising polyamides · CPC title