Polyimide-based film and preparation method thereof

Patent metadata

Field	Value
Publication number	US-2020407520-A1
Application number	US-202016912974-A
Country	US
Kind code	A1
Filing date	Jun 26, 2020
Priority date	Jun 28, 2019
Publication date	Dec 31, 2020
Grant date	—

Abstract

The embodiments relate to a polyimide-based film, which comprises a first side and a second side opposite to the first side, wherein the modulus asymmetry (MA) according to Equation 1 is 0.03 to 0.2, a process for preparing the same, and a display device comprising the same.

First claim

1 . A polyimide-based film, which comprises:
a first side and a second side opposite to the first side, wherein the modulus asymmetry (MA) according to the following Equation 1 is 0.03 to 0.2:

MA
=

AM



2

-

AM



1

AM



2

[

Equation



1

]

in Equation 1,
AM1 is an AFM modulus measured from the first side by atomic force microscopy,
AM2 is an AFM modulus measured from the second side by atomic force microscope, and
AM2 is greater than AM1.

2 . The polyimide-based film of claim 1 , wherein AM1 is 40 to 90 MPa, and AM2 is to 95 MPa.

3 . The polyimide-based film of claim 2 , wherein the difference between AM1 and AM2 is 15 MPa or less.

4 . The polyimide-based film of claim 1 , wherein the hardness asymmetry (HA) according to the following Equation 2 is 0.03 to 0.1:

HA
=

AH



2

-

AH



1

AH



2

[

Equation



2

]

in Equation 2,
AH1 is an AFM hardness measured from the first side by atomic force microscope,
AH2 is an AFM hardness measured from the second side by atomic force microscope, and
AH2 is greater than AH1.

5 . The polyamide-imide film of claim 4 , wherein AH is 15 to 40 MPa, and AH2 is 18 to 50 MPa.

6 . The polyamide-imide film of claim 5 , the difference between AH1 and AH2 is 10 MPa or less.

7 . The polyimide-based film of claim 1 , which comprises a polyamide-imide derived from an aromatic dianhydride compound, an aromatic diamine compound, and a dicarbonyl compound.

8 . The polyimide-based film of claim 7 , wherein the aromatic dianhydride compound comprises 2,2′-bis-(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride, or a combination thereof.

9 . The polyimide-based film of claim 7 , wherein the aromatic diamine compound comprises 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl.

10 . The polyimide-based film of claim 7 , wherein the dicarbonyl compound comprises terephthaloyl chloride, 1,1′-biphenyl-4,4′-dicarbonyl dichloride, isophthaloyl chloride, or a combination thereof.

11 . The polyimide-based film of claim 7 , wherein, the dicarbonyl compound comprises a first dicarbonyl compound and a second dicarbonyl compound,
the first dicarbonyl compound is terephthaloyl chloride, and the second dicarbonyl compound is 1,1′-biphenyl-4,4′-dicarbonyl dichloride, isophthaloyl chloride, or a combination thereof.

12 . The polyimide-based film of claim 7 , wherein the polyamide-imide comprises 0 to 50 parts by weight of the aromatic dianhydride compound and 50 to 100 parts by weight of the dicarbonyl compound based on 100 parts by weight of the aromatic diamine compound.

13 . The polyimide-based film of claim 1 , which has a tensile strength of 4.0 GPa or more.

14 . The polyimide-based film of claim 1 , which has a surface hardness of 2H or higher, a transmittance of 85% or more, a haze of 3% or less, and a yellow index (Y.I.) of or less.

15 . The polyimide-based film of claim 1 , which has a thickness of 10 μm to 200 μm.

16 . A process for preparing a polyimide-based film, which comprises:
simultaneously or sequentially mixing and reacting an aromatic dianhydride compound, an aromatic diamine compound, and a dicarbonyl compound in an organic solvent to prepare a polyamide-imide solution; casting the polyamide-imide solution and then drying it to prepare a gel-sheet; thermally treating the gel-sheet, while it is moved on a belt, to prepare a cured film; and winding the cured film, wherein the drying is carried out at a temperature of 60° C. to 200° C. for 10 minutes to 90 minutes, the thermal treatment is carried out at 200° C. to 450° C. for 10 minutes to 120 minutes, the AFM modulus of a first side of the cured film is 40 to 90 MPa, the AFM modulus of a second side opposite to the first side is 45 to 95 MPa, and the difference between the AFM modulus of the first side and the AFM modulus of the second side is 15 MPa or less.

17 . The process for preparing a polyimide-based film of claim 16 , wherein the drying is carried out at a temperature of 80° C. to 150° C. for 10 minutes to 20 minutes, and the thermal treatment is carried out at 380° C. to 420° C. for 10 minutes to 20 minutes.

18 . A display device, which comprises:
a display panel; and a cover window disposed on the display panel, wherein the cover window comprises a polyimide-based film, the polyimide-based film comprises a first side and a second side opposite to the first side, and the modulus asymmetry (MA) in the polyimide-based film according to the following Equation 1 is 0.03 to 0.2:

MA

Assignees

• Skc Co Ltd

Inventors

• Oh Dae Seong
• Ki Jung Hee
• Kim Sunhwan
• Kim Han Jun
• Lee Jin Woo
• Lim Dong Jin
• Jeong Dawoo

Classifications

• B29L2007/008

  Wide strips, e.g. films, webs · CPC title

• B29K2079/085

  Thermoplastic polyimides, e.g. polyesterimides, PEI, i.e. polyetherimides, or polyamideimides; Derivatives thereof · CPC title

• B29C41/46

  Heating or cooling · CPC title

• B29C41/28

  by depositing flowable material on an endless belt · CPC title

• B29C35/0277

  Apparatus with continuous transport of the material to be cured (B29C35/025, B29C35/06, B29C35/10, B29C35/14 take precedence) · CPC title