Polyimide precursor solution and polyimide film using same

Patent metadata

Field	Value
Publication number	US-2020347184-A1
Application number	US-201916961177-A
Country	US
Kind code	A1
Filing date	Sep 26, 2019
Priority date	Sep 27, 2018
Publication date	Nov 5, 2020
Grant date	—

Abstract

A polyimide precursor solution containing a reaction product of tetracarboxylic acid anhydride and diamine in a molar ratio of 1:0.93 to 1:0.99. The polyimide precursor solution contains a polyimide precursor having a number average molecular weight of at least 38,000 g/mol and can thus produce a polyimide film having high heat resistance. A polyimide precursor solution having improved storage stability can be provided by quantifying the defoaming properties of the solution and controlling the content of bubbles. Moreover, a polyimide film produced therefrom has a reduced amount of bubbles in the film, and can thus suppress the formation of cracks that can form in an inorganic layer when forming a device.

First claim

1 . A polyimide precursor solution comprising a polyimide precursor wherein the polyimide precursor is a reaction product of teteracarboxylic dianhydride and diamine in a molar ratio of 1:0.93 to 1:0.99 and has a number average molecular weight (Mn) of at least 38,000 g/mol,
wherein a T value according to Equation 1 is at least 0.9.

A
B



=


T

[

Equation



1

]

wherein,
A is a transmittance of the solution measured at a wavelength of 880 nm after leaving for 30 minutes after bubble generation in the solution at a room temperature, and
B is a transmittance of the solution measured at a wavelength of 880 nm before bubble generation.

2 . The polyimide precursor solution according to claim 1 , wherein the polyimide precursor comprises a repeating unit produced from a reaction of PDA (phenylenediamine) and BPDA (biphenyl dianhydride).

3 . The polyimide precursor solution according to claim 1 , wherein the transmittance A and transmittance B of the solution are at least 75%, respectively.

4 . The polyimide precursor solution according to claim 1 , wherein the transmittance is measured using Turbiscan.

5 . The polyimide precursor solution according to claim 1 , wherein the polyimide precursor has a number average molecular weight of less than 60,000 g/mol.

6 . The polyimide precursor solution according to claim 1 , wherein the polyimide precursor solution comprises the polyimide precursor and a pyrrolidone-based solvent.

7 . A polyimide film comprising a cured product of the polyimide precursor solution according to claim 1 .

8 . The polyimide film according to claim 7 , wherein the polyimide film has a thermal decomposition temperature, Td_5% of at least 600° C.

9 . A flexible device comprising the polyimide film according to claim 7 as a substrate.

10 . The polyimide precursor solution according to claim 2 , further comprising at least one tetracarboxylic dianhydride together with the BPDA.

11 . The polyimide precursor solution according to claim 1 , wherein the bubble generation is performed by rotating the precursor solution at 200 to 500 rpm for 20 to 60 seconds.

12 . The polyimide precursor solution according to claim 6 , wherein the pyrrolidone-based solvent is at least one solvent selected from N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone and N-vinyl-2-pyrrolidone.

13 . A method for preparing a polyimide film comprising the steps of:
applying the polyimide precursor solution of claim 1 onto a substrate; and thermal treating the applied polyimide precursor solution at 300 to 500° C. to produce the polyimide film.

14 . The method of according to 13 , further comprising drying the polyimide film at a temperature of 140° C. or lower.

Assignees

• Lg Chemical Ltd

Inventors

• Lee Jinho
• Park Jinyoung
• Park Chae Won
• Park Chan Hyo

Classifications

• C08J5/18

  Manufacture of films or sheets · CPC title

• C08G73/1067 Primary

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

• G02F1/133305

  Flexible substrates, e.g. plastics, organic film · CPC title

• C08L79/08 Primary

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

• C08J2379/08

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