Polyamide-imide-based film, preparation method thereof, and composite film and display device comprising the same

Patent metadata

Field	Value
Publication number	US-2023097107-A1
Application number	US-202217851966-A
Country	US
Kind code	A1
Filing date	Jun 28, 2022
Priority date	Aug 31, 2021
Publication date	Mar 30, 2023
Grant date	—

Abstract

The embodiments provide a polyamide-imide-based film that comprises a polyamide-imide-based polymer and has an rSE value of 0.8 to 1.25 as represented by the following Equation 1, whereby it is excellent in adhesion to a hard coating layer and light resistance to a UV light source, a process for preparing the same, and a composite film and a display device comprising the same. <Equation 1> rSE=SE1/SE2 In Equation 1, SE1 is the surface energy (dyne) of a first side of the film, and SE2 is the surface energy (dyne) of a second side of the film.

First claim

1 . A polyamide-imide-based film, which comprises a polyamide-imide-based polymer and has an rSE value of 0.8 to 1.25 as represented by the following Equation 1:
r SE=SE1/SE2  <Equation 1>
in Equation 1, SE1 is the surface energy (dyne) of a first side of the film, and SE2 is the surface energy (dyne) of a second side of the film.

2 . The polyamide-imide-based film of claim 1 , wherein SE1 is 35 dynes to 60 dynes, and SE2 is 35 dynes to 60 dynes.

3 . The polyamide-imide-based film of claim 1 , which has a dAp value of 8° or less as represented by the following Equation 2:
dAp=Ap 2− Ap 1|  <Equation 2>

in Equation 2, Ap1 is the contact angle (°) of water to the first side of the film, and Ap2 is the contact angle (°) of water to the second side of the film.

4 . The polyamide-imide-based film of claim 1 , which has a dAd value of 13° or less as represented by the following Equation 3:
dAd=|Ad 2− Ad 1|  <Equation 3>

in Equation 3, Ad1 is the contact angle (°) of diiodomethane to the first side of the film, and Ad2 is the contact angle (°) of diiodomethane to the second side of the film.

5 . The polyamide-imide-based film of claim 1 , wherein the contact angle (Ap1) of water to the first side of the polyamide-imide-based film is 60° to 83°, and the contact angle (Ap2) of water to the second side of the polyamide-imide-based film is 60° to 85°.

6 . The polyamide-imide-based film of claim 1 , wherein the contact angle (Ad1) of diiodomethane to the first side of the polyamide-imide-based film is 30° to 50°, and the contact angle (Ad2) of diiodomethane to the second side of the polyamide-imide-based film is 30° to 55°.

7 . The polyamide-imide-based film of claim 1 , which further comprises at least one selected from the group consisting of a filler, a blue pigment, and a UVA absorber.

8 . The polyamide-imide-based film of claim 1 , wherein the polyamide-imide-based polymer comprises an imide-based repeat unit and an amide-based repeat unit at a molar ratio of 2:98 to 70:30.

9 . A polyamide-imide-based composite film, which comprises a polyamide-imide-based film and a functional layer, wherein the polyamide-imide-based film comprises a polyamide-imide-based polymer and has an rSE value of 0.8 to 1.25 as represented by the following Equation 1:
r SE=SE1/SE2  <Equation 1>
in Equation 1, SE1 is the surface energy (dyne) of a first side of the polyamide-imide-based film, and SE2 is the surface energy (dyne) of a second side of the polyamide-imide-based film.

10 . The polyamide-imide-based composite film of claim 9 , wherein the functional layer further comprises a hard coating layer, when it is subjected to the cross-hatch test, the adhesion between the polyamide-imide-based film and the hard coating layer is 5B or more, and when the polyamide-imide-based film is irradiated with a UV ray having a wavelength of 340 nm at a dose of 0.63 W/m 2 and a temperature of 60° C. for 72 hours and then subjected to the cross-hatch test, the adhesion between the polyamide-imide-based film and the hard coating layer is 4B or more.

11 . A display device, which comprises a display unit; and a cover window disposed on the display unit, wherein the cover window comprises a polyamide-imide-based film and a functional layer, and the polyamide-imide-based film comprises a polyamide-imide-based polymer and has an rSE value of 0.8 to 1.25 as represented by the following Equation 1:
r SE=SE1/SE2  <Equation 1>
in Equation 1, SE1 is the surface energy (dyne) of a first side of the polyamide-imide-based film, and SE2 is the surface energy (dyne) of a second side of the polyamide-imide-based film.

12 . A process for preparing the polyamide-imide-based film of claim 1 , which comprises:
polymerizing a diamine compound, a dianhydride compound, and a dicarbonyl compound in an organic solvent to prepare a polyamide-imide-based polymer solution; casting the solution and then drying it to prepare a gel sheet; and thermally treating the gel sheet, wherein the process comprises, before casting the polyamide-imide-based polymer solution, stirring the solution.

13 . The process for preparing the polyamide-imide-based film according to claim 12 , wherein the step of stirring the solution is carried out at a temperature of 0° C. to 25° C. and at a rotation speed of 120 rpm to 500 rpm.

14 . The process for preparing the polyamide-imide-based film according to claim 12 , wherein the step of preparing a polyamide-imide-based polymer solution comprises adding a filler dispersed in an organic solvent, and the filler has a diameter (D50) of 50 nm to 1,000 nm as dissolved in an organic solvent.

15 . The process for preparing the polyamide-imide-based film according to claim 12 , wherein the step of preparing a polyamide-imide-based polymer solution comprises adding a filler dispersed in an organic solvent, and the filler contained in the polyamide-imide-based polymer solution has a diameter (D50) of 500 nm to 3,000 nm after the solution is stirred.

Assignees

• Skc Co Ltd
• Skc Hi Tech & Marketing Co Ltd

Inventors

• Kim Sun Hwan
• Oh Dae Seong
• Seo Yun-Hee
• Lee Jin Woo

Classifications

• C08J2379/08

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

• C08J2475/14

  Polyurethanes having carbon-to-carbon unsaturated bonds · CPC title

• C08G73/14

  Polyamide-imides · CPC title

• C08J7/043

  Improving the adhesiveness of the coatings per se, e.g. forming primers (adhesives in the form of films or foils characterised by the primer layers between the polymer carriers and the adhesives C09J7/50) · CPC title

• C08J5/18 Primary

  Manufacture of films or sheets · CPC title