Optical film having excellent folding performance and display device comprising same

Patent metadata

Field	Value
Publication number	US-2024255676-A1
Application number	US-202118560376-A
Country	US
Kind code	A1
Filing date	Dec 24, 2021
Priority date	Jul 14, 2021
Publication date	Aug 1, 2024
Grant date	—

Abstract

The present invention provides: an optical film comprising a polymer resin and having the yellowness index of 3.0 or less and the folding performance parameter of 1.5 GPa or less; and a display device comprising the optical film.

First claim

1 . An optical film comprising a polymer resin and having a yellowness index of 3.0 or less and a parameter of restoring force after folding, calculated using the following Equation 1, of 1.5 GPa or less:

Parameter
⁢

of
⁢

restoring
⁢

force
⁢

after
⁢

folding

=

E
′

*
d

{

(

1000
*
R

)

+

d
2

}

[

Equation
⁢

1

]

wherein R is 0.5 mm, which is a radius of curvature of the optical film in a centerline of a fold when folded;
d is a thickness of the optical film, which is expressed as μm; and
E′ is an elastic strain index calculated using the following Equation 2,
wherein only numbers, excluding units, are applied to the radius of curvature and thickness in Equation 1,

Elastic
⁢

strain
⁢

index
⁢

(

E
′

)

=

E
/

(

1
-

v
2

)

[

Equation
⁢

2

]

wherein E is a modulus of the optical film, expressed as GPa, and
v is a Poisson's ratio of the optical film.

2 . The optical film according to claim 1 , wherein the elastic strain index (E′) calculated using Equation 2 is 5.5 or more.

3 . The optical film according to claim 1 , wherein the polymer resin comprises an imide repeating unit and an amide repeating unit.

4 . The optical film according to claim 3 , wherein the amide repeating unit is present in an amount of 80% or more of a total number of the imide repeating unit and the amide repeating unit.

5 . The optical film according to claim 3 , wherein the imide repeating unit comprises a first repeating unit and a second repeating unit.

6 . The optical film according to claim 3 , wherein the amide repeating unit comprises a third repeating unit and a fourth repeating unit.

7 . The optical film according to claim 5 , wherein the first repeating unit is an imide repeating unit formed by polymerization of a first diamine-based compound and a first dianhydride-based compound, and
the second repeating unit is an imide repeating unit formed by polymerization of a second diamine-based compound and a second dianhydride-based compound.

8 . The optical film according to claim 6 , wherein the third repeating unit is an amide repeating unit formed by polymerization of the first diamine-based compound and a first dicarbonyl-based compound, and
the fourth repeating unit is an amide repeating unit formed by polymerization of a second diamine-based compound and a second dicarbonyl-based compound.

9 . The optical film according to claim 7 , wherein the first diamine-based compound is 2,2′-bis(trifluoromethyl)benzidine (TFDB).

10 . The optical film according to claim 7 , wherein the second diamine-based compound comprises at least one functional group selected from the group consisting of sulfonyl, carbonyl, methylene, propylene, and halogens.

11 . The optical film according to claim 7 , wherein the second diamine-based compound comprises at least one selected from the group consisting of bis(3-aminophenyl)sulfone (3DDS), bis(4-aminophenyl)sulfone (4DDS), 2,2-bis(3-aminophenyl)hexafluoropropane (3,3′-6F), 2,2-bis(4-aminophenyl)hexafluoropropane (4,4′-6F), 4,4′-methylenedianiline (MDA), 3,3′-diaminobenzophenone, 4,4′-diaminobenzophenone, and tetrachloride benzidine (CIBZ).

12 . The optical film according to claim 7 , wherein a molar ratio of the polymerized first diamine-based compound and the polymerized second diamine-based compound is 95:5 to 50:50.

13 . The optical film according to claim 1 , wherein the polymer resin has a weight average molecular weight (Mw) of 200,000 to 500,000.

14 . A display device comprising:
a display panel; and the optical film according to claim 1 disposed on the display panel.

15 . The optical film according to claim 8 , wherein the first diamine-based compound is 2,2′-bis(trifluoromethyl)benzidine (TFDB).

16 . The optical film according to claim 8 , wherein the second diamine-based compound comprises at least one functional group selected from the group consisting of sulfonyl, carbonyl methylene propylene and halogens.

17 . The optical film according to claim 8 , wherein the second diamine-based compound comprises at least one selected from the group consisting of bis(3-aminophenyl)sulfone (3DDS), bis(4-aminophenyl)sulfone (4DDS), 2,2-bis(3-aminophenyl)hexafluoropropane (3,3′-6F), 2,2-bis(4-aminophenyl)hexafluoropropane (4,4′-6F), 4,4′-methylenedianiline (MDA), 3,3′-diaminobenzophenone 4,4′-diaminobenzophenone, and tetrachloride benzidine (CIBZ).

18 . The optical film according to claim 8 , wherein a molar ratio of the polymerized first

Assignees

• Kolon Inc

Inventors

• Jung Hak-Gee
• Park Hyo Jun

Classifications

• C08L2203/16

  used for films · CPC title

• C08L79/08

  Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors · CPC title

• C08G73/1067

  Wholly aromatic polyimides, i.e. having both tetracarboxylic and diamino moieties aromatically bound · CPC title

• C08G73/1064

  containing sulfur · CPC title

• C08G73/1039

  comprising halogen-containing substituents · CPC title