Method for manufacturing polyimide-based film and polyimide-based film manufacture

Patent metadata

Field	Value
Publication number	US-12427709-B2
Application number	US-202318153388-A
Country	US
Kind code	B2
Filing date	Jan 12, 2023
Priority date	Dec 4, 2018
Publication date	Sep 30, 2025
Grant date	Sep 30, 2025

Abstract

The present invention relates to a method for manufacturing a polyimide-based film and a polyimide-based film manufactured thereby and, particularly, to a method for manufacturing a polyimide-based film and a polyimide-based film manufactured thereby, wherein the polyimide-based film is useful as a cover substrate for a flexible electronic device since flexure characteristics thereof, represented by yield elongation, are excellent.

First claim

The invention claimed is:

1. A polyimide-based film manufactured by a roll-to-roll manner, the roll-to-roll manner comprising:
conducting first heat treatment (S 1 ) on a polyimide-based film obtained as a gel state formed by being cast on a support while elongating the polyimide-based film at an elongation percentage of more than 100% and less than 135% in a machine direction (MD) and shrinking the polyimide-based film at a shrinkage percentage of more than 75% and less than 100% in a transverse direction (TD); and
conducting second heat treatment (S 2 ) on the first heat-treated polyimide-based film while further elongating the polyimide-based film in the machine direction (MD) at a tension not less than 30 N/mm 2 and less than 160 N/mm 2 ,
wherein a maximum heating temperature during the first heat treatment is 250° C. to 330° C., and
the second heat treatment is performed for 200 seconds or longer at a temperature within −10° C. to +30° C. of the maximum heating temperature reached during the first heat treatment,
wherein the polyimide-based film has a yield strain in a uniaxial direction of 3% or more and less than 8%.

2. The polyimide-based film according to claim 1 , wherein, in step (S 1 ), the elongation percentage in the machine direction is 105% to 130%.

3. The polyimide-based film according to claim 1 , wherein, in step (S 1 ), the elongation percentage in the machine direction is 115% to 130%.

4. The polyimide-based film according to claim 1 , wherein, in step (S 1 ), the shrinkage percentage in the traverse direction is 80% to less than 100%.

5. The polyimide-based film according to claim 4 , wherein, in step (S 1 ), the shrinkage percentage in the transverse direction is 80% to 95%.

6. The polyimide-based film according to claim 1 , wherein, in step (S 2 ), the time for second heat treatment is not less than 200 seconds and less than 1,500 seconds.

7. The polyimide-based film according to claim 1 , wherein, in step (S 2 ), the tension is 30 N/mm 2 to 150 N/mm 2 .

8. The polyimide-based film according to claim 1 , wherein the polyimide-based film has a pencil hardness of 1H or more based on ASTM D3363 measurement, and a yellowness of 5.0 or less and a light transmittance of 85% or more at 550 nm based on measurement with a CM-3700D produced by Konica Minolta, Inc.

9. A polyimide-based film having a yield strain in a uniaxial direction of 3% or more and less than 8%, a pencil hardness of 1H or more based on ASTM D3363 measurement, and a yellowness of 5.0 or less and a light transmittance of 85% or more at 550 nm based on measurement with a CM-3700D produced by Konica Minolta, Inc.

Assignees

• Kolon Inc

Inventors

• Hong Ki Ii
• Jung Hak-Gee

Classifications

• B32B2307/536

  Hardness · CPC title

• B32B27/281

  comprising polyimides · CPC title

• B32B2307/54

  Yield strength; Tensile strength · CPC title

• B32B2307/412

  Transparent · CPC title

• B32B2457/20

  Displays, e.g. liquid crystal displays, plasma displays · CPC title