Photoalignment polyimide copolymer and liquid crystal alignment layer

Patent metadata

Field	Value
Publication number	US-9791745-B2
Application number	US-201314010274-A
Country	US
Kind code	B2
Filing date	Aug 26, 2013
Priority date	Sep 7, 2012
Publication date	Oct 17, 2017
Grant date	Oct 17, 2017

Abstract

Disclosed therein are a photoalignment polyimide copolymer making it easier to form a liquid crystal alignment layer with excellences in alignment properties, thermal and structural stabilities, and adhesiveness to a substrate, and a liquid crystal alignment layer using the same. The photoalignment polyimide copolymer includes all the three types of repeating units each having a defined structure.

First claim

What is claimed is:

1. A photoalignment polyimide copolymer comprising repeating units of the following formulas 1, 2 and 3:

wherein each of p, q and r is independently 20 to 2,000;
each of X 1 , X 2 and X 3 is independently a quaternary organic radical derived from a cyclic acid dianhydride or an aromatic acid dianhydride;
each of Y 1 , Y 2 and Y 3 is independently a divalent organic radical derived from a phenylenediamine;
R 1 is a monovalent functional group of cinnamic acid, provided as a substituent to Y 1 ;
R 2 is a linear alkyl group having 8 to 30 carbon atoms provided as a substituent to Y 2 ; and
R 3 is a monovalent functional group of 2-carboxyethyl acrylate, provided as a substituent to Y 3 ,
wherein a molar ratio of the repeating units (the repeating unit of the formula 1:the repeating unit of the formula 2:the repeating unit of the formula 3) is 4 to 8:0.5 to 4:0.5 to 3.

2. The photoalignment polyimide copolymer as claimed in claim 1 , wherein the cyclic acid dianhydride or the aromatic acid dianhydride comprises at least one selected from the group consisting of 1,2,3,4-cyclobutane-tetracarboxylic acid dianhydride (CBDA), dioxotetrahydrofuryl)-3-methylcyclohexene-1,2-dicarboxylic acid dianhydride (DOCDA), bicyclooctene-2,3,5,6-tetracarboxylic acid dianhydride (BODA), 1,2,3,4-cyclopentane-tetracarboxylic acid dianhydride (CPDA), 1,2,4,5-cyclohexane-tetracarboxylic acid dianhydride (CHDA), 1,2,4-tricarboxy-3-methylcarboxy cyclopentane dianhydride, 1,2,3,4-tetracarboxycyclopentane dianhydride, pyromellitic acid dianhydride (PMDA), biphthalic acid dianhydride (BPDA), oxydiphthalic acid dianhydride (ODPA), benzophenone-tetracarboxylic acid dianhydride (BTDA), and hexafluoroisopropylidenediphthalic acid dianhydride (6-FDA).

3. The photoalignment polyimide copolymer as claimed in claim 1 , wherein the photoalignment polyimide copolymer has a weight average molecular weight of 10,000 to 500,000.

4. A liquid crystal alignment layer comprising a photoalignment layer, wherein the photoalignment layer comprises the photoalignment polyimide copolymer as claimed in claim 1 or a photocured material thereof.

5. The liquid crystal alignment layer as claimed in claim 4 , further comprising a liquid crystal layer on the photoalignment layer.

6. The liquid crystal alignment layer as claimed in claim 4 , wherein the photoalignment layer comprises a photocured material of the photoalignment polyimide copolymer having a photocurable functional group R 3 crosslinked thereto.

7. The liquid crystal alignment layer as claimed in claim 4 , wherein the liquid crystal alignment layer has a thickness of 30 to 200 nm.

8. A liquid crystal cell comprising the liquid crystal alignment layer as claimed in claim 4 .

9. The liquid crystal cell as claimed in claim 8 , wherein the liquid crystal cell is used for IPS (In-Plane Switching) liquid crystal.

10. The liquid crystal cell as claimed in claim 8 , wherein the liquid crystal cell is used for TN (Twisted-Nematic) liquid crystal.

Assignees

• Lg Chemical Ltd

Inventors

• Hwang Seung-Yeon
• Chun Sung-Ho
• Yoo Dong-Woo
• Jang Hyeong-Bin

Classifications

• B32B2457/202

  LCD, i.e. liquid crystal displays · CPC title

• G02F1/133723 Primary

  Polyimide, polyamide-imide · CPC title

• C08G73/1085

  Polyimides with diamino moieties or tetracarboxylic segments containing heterocyclic moieties · CPC title

• Y10T428/1005

  Cross-Sectional Technologies · mapped topic

• C08G73/1007

  from tetracarboxylic acids or derivatives and diamines · CPC title