Liquid crystal aligning agent, liquid crystal alignment layer comprising the same and method for preparing liquid crystal alignment layer

Patent metadata

Field	Value
Publication number	US-10526540-B2
Application number	US-201715565878-A
Country	US
Kind code	B2
Filing date	Mar 28, 2017
Priority date	Mar 28, 2016
Publication date	Jan 7, 2020
Grant date	Jan 7, 2020

Abstract

The present invention relates to a liquid crystal aligning agent for use as an alignment layer for liquid crystal display. More specifically, the present invention relates to a liquid crystal aligning agent capable of improving an imidization rate and thus exhibiting an excellent alignment state, a liquid crystal alignment layer comprising the same, a preparation method thereof and a liquid crystal display comprising the liquid crystal alignment layer.

First claim

What is claimed is:

1. A liquid crystal aligning agent comprising: at least one selected group the group consisting of a polyimide precursor including a repeating unit represented by Chemical Formula 1 below and a terminal group represented by Chemical Formula 2 below; and a polyimide including a repeating unit represented by Chemical Formula 3 below and a terminal group represented by Chemical Formula 2 below:

in Chemical Formulae 1 to 3,
X is each independently a tetravalent organic group,
R is each independently hydrogen or a C 1-10 alkyl group,
R a and R b are each independently hydrogen or a C 1-10 alkyl group,
R 1 is hydrogen or a C 1-10 alkyl group,
R 2 is a tert-butoxycarbonyl group or a 9-fluorenylmethoxycarbonyl group,
A is —O—, —S—, —NH— or a C 1-10 alkylene group,
B is at least one bivalent functional group selected from the group consisting of a C 1-10 alkylene group, a C 6-20 arylene group, a C 7-20 arylalkylene group,

and
Z is 0 or 1.

2. The liquid crystal aligning agent of claim 1 , wherein X is each independently at least one functional group selected from the group consisting of Chemical Formulae 4 to 7 below:

in Chemical Formulae 6 and 7,
R 3 to R 6 are each independently at least one bivalent functional group selected from the group consisting of a direct bond, —O—, —S—, —C(O)—, —S(O)—, —C(O)O—, —O(C)O—, C 1-10 alkylene and —C(R′)(R″)—, wherein the R′ and R″ are each independently a C 1-10 alkyl group substituted or unsubstituted with hydrogen or halogen.

3. The liquid crystal aligning agent of claim 1 , wherein the polyimide precursor has a weight average molecular weight of 5,000 to 100.000 g/mol.

4. The liquid crystal aligning agent of claim 1 , wherein the polyimide has a weight average molecular weight of 5,000 to 100.000 g/mol.

5. The liquid crystal aligning agent of claim 1 , in a state of being dissolved in an organic solvent.

6. The liquid crystal aligning agent of claim 5 , wherein the organic solvent is selected from cyclopentanone, cyclohexanone, N-methylpyrrolidone, DMF (dimethylformamide), acetamide, γ-butyrolactone, 2-butoxyethanol and a mixture thereof.

7. The liquid crystal aligning agent of claim 5 , wherein the solid concentration of the polyimide precursor and polyimide is 0.5 to 30% by weight.

8. A liquid crystal alignment layer comprising the liquid crystal aligning agent of claim 1 .

9. The liquid crystal alignment layer of claim 8 , wherein the thickness thereof is 50 to 300 nm.

10. A method for preparing a liquid crystal alignment layer comprising:
coating the liquid crystal aligning agent of claim 1 onto a substrate to form a coating layer;
drying the coating layer;
irradiating the surface of the dried coating layer with polarized ultraviolet light to perform alignment treatment; and
heat-treating the alignment-treated coating layer.

11. The method for preparing a liquid crystal alignment layer of claim 10 , wherein the drying step is carried out at 50 to 150° C. for 10 to 300 seconds.

Assignees

• Lg Chemical Ltd

Inventors

• Kwon Soon Ho
• Jo Jung Ho
• Park Hang Ah
• Yun Hyeong Seuk
• Han Hee
• Yoon Jun Young

Classifications

• G02F1/133723

  Polyimide, polyamide-imide · CPC title

• C08G73/16

  Polyester-imides · CPC title

• G02F1/1337

  Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers · CPC title

• C09K19/56 Primary

  Aligning agents · CPC title

• C08G73/1067

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