Liquid crystal composition, liquid crystal display device including the same, and method of manufacturing liquid crystal display device

Abstract

A liquid crystal composition including: a liquid crystal compound and a liquid crystal aligning agent including at least one compound represented by Formula 1:

Description

This application claims priority to Korean Patent Application No. 10-2016-0007512 filed on Jan. 21, 2016, and Korean Patent Application No. 10-2016-0181120, filed on Dec. 28, 2016, and all the benefits accruing therefrom under 35 U.S.C. § 119, the disclosures of which in their entirety are herein incorporated by reference.

BACKGROUND

1. Field

The present disclosure relates to a liquid crystal composition, a liquid crystal display device including the same, and a method of manufacturing a liquid crystal display device.

2. Description of the Related Art

A liquid crystal display device, which is one of the most widely used display devices, generally includes a display substrate containing a pixel electrode, a counter display substrate including a common electrode, a liquid crystal layer disposed between the display substrate and the counter display substrate, and a liquid crystal alignment film disposed between the liquid crystal layer and at least one of the display substrate and the counter display substrate.

An example of a method of arranging liquid crystal compounds in a direction perpendicular to a display substrate or a counter display substrate includes using a liquid crystal alignment film. The liquid crystal alignment film may be manufactured by coating the surface of at least one of a display substrate and a counter display substrate with an organic polymer compound or an inorganic compound such as silicon oxide to form a thin film, and subsequently drying and sintering the thin film.

Generally, a vertically aligned polyimide thin film is used as a polymer-based liquid crystal alignment film. In order to manufacture a polymer-based liquid crystal alignment film, the surface of at least one of a display substrate and a counter display substrate is coated with an alignment solution containing an organic polymer compound and an environmentally hazardous organic solvent, followed by drying, and high-temperature sintering of the coated alignment solution. Such a long series of processes may decrease productivity, cause harmful effects to humans and the environment, and therefore, are disadvantageous. Thus, there remains a need for an improved method of manufacturing the liquid crystal display device, which is devoid of the above shortcomings.

SUMMARY

Aspects of the present disclosure provide a method of manufacturing a liquid crystal display device, a liquid crystal composition used in the method, and a liquid crystal display device manufactured by the method. The method omits a prior art process of forming a liquid crystal alignment film and is characterized by improved processability and productivity.

According to an exemplary embodiment, a liquid crystal composition includes:

a liquid crystal compound; and

a liquid crystal aligning agent containing at least one compound represented by Formula 1:

wherein in Formula 1,

X—* is a C_1-20-alkyl-*,

*-L₁-* is a single bond, *—(CH₂)_p1—*, *—O(CH₂)_p1—*, *—O—*,

*—CH═CH—*, or *—C≡C—*, wherein p1 is an integer of 1 to 10;

*-L₂-* is a single bond, *—(CH₂)_p2—*, *—O(CH₂)_p2—*, *—O—*,

*—CH═CH—*, or *—C≡C—*, wherein p2 is an integer of 1 to 10;

*-L₃-* is a single bond, *—(CH₂)_p3—*, *—O(CH₂)_p3—*, *—O—*,

*—CH═CH—*, or *—C≡C—*, wherein p3 is an integer of 1 to 10;*-L₁-*, *-L₂-*, and *-L₃-* are identical to or different from one another;

*—C—* is a substituted or unsubstituted cyclic linking group, which is substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

and substituted or unsubstituted

wherein at least one hydrogen in the substituted cyclic linking group is substituted with a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or a C_1-10-((meth)acryloxy)alkyl-*;

*—R—* is *—(CH₂)_q—*, *—O(CH₂)_q—*, *—(CH₂)_qArn-*, or *—O(CH₂)_qArn-*, wherein Arn is a substituted or unsubstituted C_6-30 arylene, and q is an integer of 1 to 10, wherein at least one hydrogen in the substituted C_6-30 arylene is substituted with a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or a C_1-10-((meth)acryloxy)alkyl-*;

• • *—Y is

wherein n is an integer of 0 to 5;

n₁ is an integer of 1 to 3,

n₂ and m are each independently 0 or 1, and

“*” indicates a point of attachment.

In an exemplary embodiment,

X—* may be C_1-20-alkyl-*, and

the liquid crystal composition may further include a reactive mesogen containing at least one compound represented by Formula 2:P1-SP1-MG-SP2-P2  Formula 2

wherein in Formula 2,

P1-* and *—P2 are each independently

*—SP1-* is

and *—SP2-* is

wherein a and b are independently an integer of 0 to 2, each *-L-* is independently *—(CH₂)_c—*, *—O(CH₂)_c—*,

*—CH═CH—*, or *—C≡C—*, wherein c is an integer of 1 to 10, and *—Z—* is *—(CH₂)_d—* (wherein d is an integer of 0 to 12), and

*—Ar—* is

wherein each A-* is independently H—*, a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or *—CN; and

*-MG-* is

wherein each A-* is independently H—*, a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or *—CN.

In an exemplary embodiment, the liquid crystal aligning agent may include at least one compound represented by Formulae SA 1-1 to SA 1-21:

In an exemplary embodiment, the liquid crystal aligning agent may include the compound represented by Formula 1,

wherein X—* is

and

wherein a content of a reactive mesogen including at least one compound represented by Formula 2 may be 0 percent by weight, based on a total weight of the liquid crystal composition:P1-SP1-MG-SP2-P2  Formula 2

wherein in Formula 2,

P1-* and *—P2 are each independently

*—SP1-* is

and *—SP2-* is

wherein a and b are independently an integer of 0 to), each *-L-* is independently *—(CH₂)_c—*, *—O(CH₂)_c—*,

*—CH═CH—*, or *—C≡C—*, wherein c is an integer of 1 to 10, *—Z—* is *—(CH₂)_d—*, wherein d is an integer of 0 to 12, and *—Ar—*

wherein each A-* is independently H—*, a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or *—CN; and

• • *-MG-* is

wherein each A-* is independently H—*, a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or *—CN.

In an exemplary embodiment, the liquid crystal aligning agent may include at least one compound represented by Formulae SA 2-1 to SA 2-17:

According to an exemplary embodiment, a liquid crystal display device includes:

a first electrode;

a second electrode facing the first electrode;

a liquid crystal layer containing a liquid crystal compound, wherein the liquid crystal layer is disposed between the first electrode and the second electrode;

a liquid crystal aligning agent including at least one compound represented by Formula 1-1, wherein the liquid crystal layer is adsorbed on a surface of at least one of the first electrode and the second electrode to align the liquid crystal compound; and

a polymer of reactive mesogen including two or more compounds represented by Formula 2, wherein the polymer of reactive mesogen is adsorbed on the surface of at least one of the first electrode and the second electrode to align the liquid crystal compound:

wherein in Formula 1-1,

X′—* is a C_1-20-alkyl-*;

*-L₁-* is a single bond, *—(CH₂)_p1—*, *—O(CH₂)_p1—*, *—O—*,

*—CH═CH—*, or *—C≡C—*, wherein p1 is an integer of 1 to 10;

*-L₂-* is a single bond, *—(CH₂)_p2—*, *—O(CH₂)_p2—*, *—O—*,

*—CH═CH—*, or *—C≡C—*, wherein p2 is an integer of 1 to 10;

*-L₃-* is a single bond, *—(CH₂)_p3—*, *—O(CH₂)_p3—*, *—O—*,

*—CH═CH—*, or *—C≡C—*, wherein p3 is an integer of 1 to 10;

*-L₁-*, *-L₂-*, and *-L₃-* are identical to or different from one another;

*—C—* is a substituted or unsubstituted cyclic linking group, which is substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

or substituted or unsubstituted

wherein at least one hydrogen in the substituted cyclic linking group is substituted with a C_1-10-alkyl-*, F—*, Br—*, I*, *—OH, *—NH₂, or a C_1-10-((meth)acryloxy)alkyl-*; *—R—* is *—(CH₂)_q—*, *—O(CH₂)_q—*, *—(CH₂)_qArn-*, or *—O(CH₂)_qArn-*, wherein Arn is a substituted or unsubstituted C_6-30 arylene, and q is an integer of 1 to 10, wherein at least one hydrogen in the substituted C_6-30 arylene is substituted with a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or a C_1-10-((meth)acryloxy)alkyl-*;

*—Y is

wherein n is an integer of 0 to 5;

m is 1, and

n₂ and m are each independently 0 or 1,P1-SP1-MG-SP2-P2  Formula 2

wherein in Formula 2,

P1-* and *—P2 are each independently

*—SP1-* is

and *—SP2-* is

wherein a and b are each independently an integer of 0 to 2, each ch *-L-* is independently *—(CH₂)_c—*, *—O(CH₂)_c—*,

*—CH═CH—*, or *—C≡C—*, wherein c is an integer of 1 to 10, *—Z—* is *—(CH₂)_d—*, wherein d is an integer of 0 to 12, and *—Ar—* is

wherein each A-* is independently H—*, a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or *—CN;

*-MG-* is

wherein each A-* is independently H—*, a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or *—CN; and

“*” indicates a point of attachment.

In an exemplary embodiment, the liquid crystal aligning agent may contain at least one compound represented by Formulae SA 1-1 to SA 1-21:

According to another exemplary embodiment, a liquid crystal display device includes:

a first electrode;

a second electrode facing the first electrode;

a liquid crystal layer including a liquid crystal compound, wherein the liquid crystal layer is disposed between the first electrode and the second electrode; and

a polymer of a liquid crystal aligning agent including two or more compound represented by Formula 1-2, wherein the polymer of liquid crystal aligning agent is adsorbed on a surface of at least one of the first electrode and the second electrode to align the liquid crystal compound,

wherein an amount of a compound represented by Formula 2 is 0 percent by weight, based on a total weight of the liquid crystal layer:

wherein in Formula 1-1,

X″—* is

*-L₁-* is a single bond, *—(CH₂)_p1—*, *—O(CH₂)_p1—*, *—O—*,

*—CH═CH—*, or *—C≡C—*, wherein p1 is an integer of 1 to 10;

*-L₂-* is a single bond, *—(CH₂)_p2—*, *—O(CH₂)_p2—*, *—O—*,

*—CH═CH—*, or *—C≡C—*, wherein p2 is an integer of 1 to 10;

*-L₃-* is a single bond, *—(CH₂)_p3—*, *—O(CH₂)_p3—*, *—O—*,

*—CH═CH—*, or *—C≡C—*, wherein p3 is an integer of 1 to 10;

*-L₁-*, *-L₂-*, and *-L₃-* are identical to or different from one another;

*—C—* is a substituted or unsubstituted cyclic linking group, which is substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

or substituted or unsubstituted

wherein at least one hydrogen in the substituted cyclic linking group is substituted with a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or a C_1-10-((meth)acryloxy)alkyl-*;

*—R—* is *—(CH₂)_q—*, *—O(CH₂)_q—*, *—(CH₂)_qArn-*, or *—O(CH₂)_qArn-*, wherein Arn is a substituted or unsubstituted C_6-30 arylene, and q is an integer of 1 to 10; wherein at least one hydrogen in the substituted C_6-30 arylene is substituted with a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or a C_1-10-((meth)acryloxy)alkyl-*;

*—Y is

(wherein n is an integer of 0 to 5);

n₁ is an integer of 1 to 3, and

n₂ and m are each independently 0 or 1,P1-SP1-MG-SP2-P2  Formula 2

wherein in Formula 2,

P1-* and *—P2 are each independently

*—SP1-* is

and *—SP2-* is

wherein a and b are independently an integer of 0 to 2, each *-L-* is independently *—(CH₂)_c—*, *—O(CH₂)_c—*,

*—CH═CH—*, or *—C≡C—*, wherein c is an integer of 1 to 10, *—Z—* is *—(CH₂)_d—*, wherein d is an integer of 0 to 12, and *—Ar—* is

wherein each A-* is independently H—*, a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or *—CN; and

*-MG-* is

wherein each A-* is independently H—*, a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or *—CN.

In an exemplary embodiment, the liquid crystal aligning agent may include at least one compound represented by Formulae SA 2-1 to SA 2-17:

According to an exemplary embodiment, a method of manufacturing liquid crystal display includes:

disposing the liquid crystal composition between a first electrode and a second electrode facing the first electrode to manufacture a liquid crystal cell; and

irradiating the liquid crystal cell with ultraviolet light while applying a voltage to the liquid crystal cell.

In an exemplary embodiment, X—* may be a C_1-20-alkyl-* group, and the liquid crystal composition may further include a reactive mesogen containing at least one compound represented by Formula 2:P1-SP1-MG-SP2-P2  Formula 2

wherein in Formula 2,

P1-* and *—P2 are each independently

*—SP1-* is

and *—SP2-* is

wherein a and b are independently an integer of 0 to 2, each *-L-* is independently *—(CH₂)_c—*, *—O(CH₂)_c—*,

*—CH═CH—*, or *—C≡C—*, wherein c is an integer of 1 to 10, *—Z—* is *—(CH₂)_d—*, wherein d is an integer of 0 to 12, and *—Ar—* is

wherein each A-* is independently H—*, a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or *—CN; and *-MG-* is

wherein each A-* is independently H—*, a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or *—CN.

In an exemplary embodiment, the liquid crystal aligning agent may include at least one compound represented by Formulae SA 1-1 to SA 1-21:

In an exemplary embodiment,

the liquid crystal aligning agent may include the compound represented by Formula 1, wherein X—* is

and

a content of a reactive mesogen including at least one compound represented by Formula 2 may be 0 percent by weight, based on a total weight of the liquid crystal composition:P1-SP1-MG-SP2-P2  Formula 2

wherein in Formula 2,

P1-* and *—P2 are each independently

*—SP1-* is

and *—SP2-* is

wherein a and b are independently an integer of 0 to 2, each *-L-* is independently *—(CH₂)_c—*, *—O(CH₂)_c—*,

*—CH═CH—*, or *—C≡C—*, wherein c is an integer of 1 to 10, *—Z—* is *—(CH₂)_d—*, wherein d is an integer of 0 to 12, and *—Ar—* is

wherein each A-* is independently H—*, a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or *—CN; and *-MG-* is

wherein each A-* is independently H—*, a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or *—CN.

In an exemplary embodiment, the liquid crystal aligning agent may include at least one compound represented by Formulae SA 2-1 to SA 2-17:

As described in further detail below, according to embodiments of the present disclosure, the following effects are noted.

The liquid crystal composition according to an embodiment of the present disclosure can be used in the method of manufacturing a liquid crystal display device. The method is characterized by improved processability and productivity due to the omission of a conventional liquid crystal alignment film forming process, which includes, for example, coating, drying and sintering of an alignment solution. Thus, the method disclosed herein is both environmentally friendly and has minimal impact on the human body.

Similarly, the liquid crystal display device according to an embodiment of the present disclosure can be characterized by improved processability and productivity due to the omission of a conventional liquid crystal alignment film forming process which includes for example, coating, drying, and sintering of an alignment solution. The liquid crystal display therefore can be manufactured using a method which is environmentally friendly, and has minimal impact on the human body.

The method of manufacturing a liquid crystal display device according to another embodiment of the present disclosure can be characterized by improved processability and productivity by omitting a conventional liquid crystal alignment film forming process, which includes, for example, coating, drying, and sintering of an alignment solution. The method is thus both environmentally friendly, and has minimal impact on the human body.

However, aspects of the present disclosure are not restricted to those set forth herein.

The above and other aspects of the present disclosure will become more apparent to one of ordinary skill in the art to which the present disclosure pertains by referencing the detailed description of the present disclosure given below.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects and features of the present disclosure will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which:

FIG. 1 is a schematic exploded perspective view of a liquid crystal display device according to an embodiment of the present disclosure;

FIG. 2 is a schematic cross-sectional view of the liquid crystal display device of FIG. 1;

FIGS. 3A to 3M are graphs of intensity (arbitrary units, a.u.) versus frequency (parts per million, ppm) showing the ¹H-NMR spectrum of liquid crystal aligning agents according to embodiments of the present disclosure;

FIGS. 4A, 4B, and 4C are schematic cross-sectional views showing a method of manufacturing the liquid crystal display device of FIG. 1;

FIGS. 5A and 5B are schematic cross-sectional views showing modified embodiments of the liquid crystal display device of FIG. 1;

FIG. 6 is a schematic cross-sectional view of a liquid crystal display device according to another embodiment of the present disclosure;

FIGS. 7A through 7C are ¹H-NMR spectrums of liquid crystal aligning agents according to embodiments of the present disclosure;

FIGS. 8A, 8B, and 8C are schematic cross-sectional views showing a method of manufacturing the liquid crystal display device of FIG. 6;

FIGS. 9A and 9B are images of a liquid crystal display device according to Example 2-1;

FIGS. 10A and 10B are images of a liquid crystal display device according to Example 2-2;

FIGS. 10C and 10D are scanning electron microscope (SEM) images of the liquid crystal display device according to Example 2-2;

FIG. 11 is a graph illustrating the voltage holding ratio versus ultraviolet light (UV) irradiation time (minutes, min) for the liquid crystal display device of Example 2-4; and

FIGS. 12A and 12B are images of a liquid crystal display device according to Comparative Example 1.

DETAILED DESCRIPTION

Features of the inventive concept and methods of accomplishing the same may be understood more readily by reference to the following detailed description of exemplary embodiments and the accompanying drawings.

The inventive concept may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concept of the inventive concept to those skilled in the art, and the inventive concept will only be defined by the appended claims.

In the drawings, the thickness of layers and regions are exaggerated for clarity. It will be understood that when an element or layer is referred to as being “on,” “connected to” or “coupled to” another element or layer, the element or layer can be directly on, connected or coupled to another element or layer or intervening elements or layers. In contrast, when an element is referred to as being “directly on,” “directly connected to” or “directly coupled to” another element or layer, there are no intervening elements or layers present. As used herein, connected may refer to elements being physically, electrically and/or fluidly connected to each other.

Like numbers refer to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of the disclosure.

Spatially relative terms, such as “bottom,” “below,” “lower,” “under,” “above,” “upper,” “top” and the like, may be used herein for ease of description to describe the relationship of one element or feature to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” relative to other elements or features would then be oriented “above” relative to the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including,” when used in this specification, specify the presence of stated features, integers, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

“About” or “approximately” as used herein is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the limitations of the measurement system). For example, “about” can mean within one or more standard deviations, or within ±30%, 20%, 10%, 5% of the stated value.”

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Exemplary embodiments are described herein with reference to cross section illustrations that are schematic illustrations of idealized embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as flat may have rough and/or nonlinear features. Moreover, sharp angles that are illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the present claims.

As used herein, when a definition is not otherwise provided, the term “substituted” refers to a compound or group substituted with at least one (e.g., 1, 2, 3, or 4) substituent selected from a C_1-30 alkyl group, a C_2-30 alkynyl group, a C_6-30 aryl group, a C_7-30 alkylaryl group, a C_1-30 alkoxy group, a C_1-30 heteroalkyl group, a C_3-30 heteroalkylaryl group, a C_3-30 cycloalkyl group, a C_3-15 cycloalkenyl group, a C_6-30 cycloalkynyl group, a C_2-30 heterocycloalkyl group, a halogen (—F, —Cl, —Br or —I), a hydroxy group (—OH), a nitro group (—NO₂), a cyano group (—CN), an amino group (—NRR′, wherein R and R are each independently hydrogen or a C_1-6 alkyl group), an azido group (—N₃), an amidino group (—C(═NH)NH₂), a hydrazino group (—NHNH₂), a hydrazono group (═N(NH₂), an aldehyde group (—C(═O)H), a carbamoyl group (—C(O)NH₂), a thiol group (—SH), an ester group (—C(═O)OR, wherein R is a C_1-6 alkyl group or a C_6-12 aryl group), a carboxylic acid group (—COOH) or a salt thereof (—C(═O)OM, wherein M is an organic or inorganic cation), a sulfonic acid group (—SO₃H) or a salt thereof (—SO₃M, wherein M is an organic or inorganic cation), a phosphoric acid group (—PO₃H₂) or a salt thereof (—PO₃MH or —PO₃M₂, wherein M is an organic or inorganic cation), and a combination thereof, instead of hydrogen, provided that the substituted atom's normal valence is not exceeded.

As used herein, when a definition is not otherwise provided, the term “hetero” refers to a compound or group including 1 to 3 heteroatoms, wherein the heteroatom(s) is each independently N, O, S, Si, or P.

As used herein, when a definition is not otherwise provided, the term “alkyl group” refers to a straight or branched chain, saturated aliphatic hydrocarbon having the specified number of carbon atoms and having a valence of at least one.

As used herein, when specific definition is not otherwise provided, the term “(meth)acryloxy)alkyl” refers to both “acryloxyalkyl” [CH₂═CH—C(═O)—O-alkyl-] and “methacryloxyalkyl” [CH₂═C(CH₃)—C(═O)—O-alkyl-], wherein the term “alkyl” has the same meaning as described above.

As used herein, when a definition is not otherwise provided, the term “arylene group” refers to a functional group having a valence of at least two obtained by removal of two hydrogens from one or more rings in an aromatic hydrocarbon, wherein the hydrogen atoms may be removed from the same or different rings, each of which rings may be aromatic or nonaromatic, and the arylene group may be optionally substituted with one or more substituents where indicated, provided that the valence of the alkylene group is not exceeded.

When a group containing a specified number of carbon atoms is substituted with any of the groups listed in the preceding paragraph, the number of carbon atoms in the resulting “substituted” group is defined as the sum of the carbon atoms contained in the original (unsubstituted) group and the carbon atoms (if any) contained in the substituent. For example, when the term “substituted C_6-30 arylene” refers to a C_6-30 arylene group substituted with a C_1-10 alkyl group, the total number of carbon atoms in the resulting alkyl substituted arylene group is C_7-40.

In the present specification, the term “C_A-B” means that the number of carbon atoms is A to B. In the present specification, the symbol “*” is defined as a bonding site (i.e., a point of attachment.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings.

FIG. 1 is a schematic exploded perspective view of a liquid crystal display device 500 according to an embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view of the liquid crystal display device 500 of FIG. 1.

Referring to FIG. 1, the liquid crystal display device 500 may be configured to include: a display substrate SUB1; a counter display substrate SUB2 disposed to face the display substrate SUB1 and to be spaced apart from the display substrate SUB1 while maintaining a predetermined distance; and a liquid crystal layer 300 disposed between the display substrate SUB1 and the counter display substrate SUB2. The liquid crystal layer 300 may include liquid crystal compounds 301, and the liquid crystal compounds 301 may have negative dielectric anisotropy.

The liquid crystal display device 500 includes a display area I and a non-display area II. The display area I is an area in which an image is displayed. The non-display area II is a peripheral area surrounding the display area I, and is an area in which an image is not displayed.

The display substrate SUB1 may include a plurality of gate lines GL extending in a first direction D1 and a plurality of data line DL extending in a second direction D2, which is perpendicular to the first direction D1. Although not shown in the drawings, the gate lines GL are not disposed only in the display area I, and may extend to the non-display area II. In this case, the non-display area II may be provided with a gate pad (not shown). That is, in the non-display area II, the display substrate SUB1 may include a gate pad (not shown). Further, the data lines DL are not disposed only in the display area I, and may extend to the non-display area II. In this case, the non-display area II may be provided with a data pad (not shown). That is, in the non-display area II, the display substrate SUB1 may include a data pad (not shown).

A plurality of pixels PX defined by the gate lines GL the data lines DL may be disposed in the display area I. The plurality of pixels PX may be arranged in the form of a matrix, and a pixel electrode 180 may be disposed for each of the pixels PX. In this case, in the display area I, the display substrate SUB1 may include the plurality of pixels PX arranged in the form of a matrix and the plurality of pixel electrodes 180 arranged in the form of a matrix.

In the non-display area II, a drive unit (not shown) for providing a gate drive signal and a data drive signal to each of the pixels PX may be disposed. In this case, in the non-display area II, the display substrate SUB1 may include the drive unit (not shown). The drive unit (not shown) may generate a gate drive signal and a data drive signal corresponding to a drive frequency of about 120 Hertz (Hz) or more.

Referring to FIGS. 1 and 2, the display substrate SUB1 may be configured to include a switching element array substrate 100 and a first electrode 180. The switching element array substrate 100 may be configured to include a first base substrate (not shown) made of glass or a polymer and a switching element (not shown) disposed on the first base substrate. The switching element (not shown), for example, may be a thin film transistor. The counter display substrate SUB2 may be configured to include a second base substrate 210 made of glass or a polymer and a second electrode 250. The first electrode 180 generates an electric field together with the second electrode 250 to control the alignment direction of liquid crystal compounds 301 in the liquid crystal layer 300 disposed therebetween. The first electrode 180 may be a pattern electrode having at least one of a projection pattern and a slit pattern, or may be a patternless electrode. The second electrode may be the pattern electrode or the patternless electrode. In the liquid crystal display device 500, for example, the first electrode 180 may be the pattern electrode, and the second electrode 250 may the patternless electrode.

A first liquid crystal aligning agent AA1 containing at least one compound represented by Formula 1-1 below and reactive mesogen polymer projections (RMP) obtained by the polymerization of two or more of compounds represented by Formula 1-2 below, may be adsorbed on a surface of at least one of the first electrode 180 and the second electrode 250. Here, the surface of the first electrode 180 and the surface of the second electrode 250 are defined as an interface between the liquid crystal layer 300 and the first electrode 180 and as an interface between the liquid crystal layer 300 and the second electrode 250, respectively.

In Formula 1-1, X′—*, which is a functional group capable of arranging the liquid crystal compounds 301 in a direction substantially perpendicular to the display substrate SUB1 and the counter display substrate SUB2, may be a C_1-20-alkyl-*.

In Formula 1-1, *-L₁-*, which is a linking group, may be a single bond, *—(CH₂)_p1—*, *—O(CH₂)_p1—*, *—O—*,

*—CH═CH—*, or *—C≡C. p1 may be an integer of 1 to 10.

In Formula 1-1, *-L₂-*, which is a linking group, may be a single bond, *—(CH₂)_p2—*, *—O(CH₂)_p2—*, *—O—*,

*—CH═CH—*, or *—C≡C. p2 may be an integer of 1 to 10.

In Formula 1-1, *-L₃-*, which is a linking group, may be a single bond, *—(CH₂)_p3—*, *—O(CH₂)_p3—*, *—O—*,

*—CH═CH—*, or *—C≡C—*. p3 may be an integer of 1 to 10.

*-L₁-*, *-L₂-*, and *-L₃-* may be identical to or different from one another.

In Formula 1-1, *—R—*, which is a spacer for maintaining the length of the first liquid crystal aligning agent (AA1) in a long chain direction, may be *—(CH₂)_q—*, *—O(CH₂)_q—*, *—(CH₂)_qArn-*, or *—O(CH₂)_qArn-*. Am may be a substituted or unsubstituted C_6-30 arylene, and q is an integer of 1 to 10. The substituted C_6-30 arylene is defined as a C_6-30 arylene in which at least one hydrogen group is substituted with a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or a C_1-10-((meth)acryloxy)alkyl-*.

In Formula 1-1, n₁ may be an integer of 1 to 3, and n₂ and m may be each independently 0 or 1.

In Formula 1-1, *—C—*, which is a functional group for improving the miscibility of the liquid crystal aligning agent with the liquid crystal compounds 301, is a substituted or unsubstituted cyclic linking group. In Formula 1-1, *—C—* may be substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

or substituted or unsubstituted

The substituted cyclic linking group is defined as a cyclic linking group in which at least one hydrogen group (H—*) is substituted with a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or a C_1-10-((meth)acryloxy)alkyl-*.

In Formula 1-1, *—Y, which is a monovalent atomic group including a hetero ring, may be a functional group for improving the adsorption of the first liquid crystal aligning agents AA1 to at least one of the first electrode 180 and the second electrode 250. For example, *—Y may be a C₂-C₃₀ monovalent atomic group including one or more C₂-C₅ heterocyclic structures having nitrogen atoms and/or oxygen atoms in a hetero ring. The hetero ring having the nitrogen atoms and/or the oxygen atoms may be substituted or unsubstituted.

In an exemplary embodiment, in Formula 1-1, *—Y may be

Here, n may be 0 to 5.P1-SP1-MG-SP2-P2  Formula 2

In Formula 2, P1-* and *—P2 are polymerizable groups of the reactive mesogen, and may be each independently

In Formula 2, *—SP1-*, which is a linking group, may be

(wherein a may be 0 to 2), and *—SP2-*, which is a linking group, may be

(wherein b may be 0 to 2). In Formula 2, *-MG-*, which is a functional group for improving the miscibility with the liquid crystal compounds 301, may be

In each of *—SP1-* and *—SP2-*, *-L-* may be *—(CH₂)_c—*, *—O(CH₂)_c—*,

*—CH═CH—*, or *—C≡C—* (wherein c may be an integer of 1 to 10), and *—Z—* may be *—(CH₂)_d—* (wherein d may be an integer of 0 to 12). In each of *—SP1-* and *—SP2-*, *—Ar—*, which is a functional group for improving the miscibility with the liquid crystal compounds 301, may be

In each of *—SP1-*, *—SP2-* and *-MG-*, each A-* may be independently H—*, a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or *-*—CN.

The liquid crystal display device 500 can align the liquid crystal compounds 301 using the first liquid crystal aligning agents AA1 and the reactive mesogen polymer projections RMP.

The first liquid crystal aligning agent particle AA1 can align the liquid crystal compounds 301 in a direction substantially perpendicular to at least one of the display substrate SUB1 and the counter display substrate SUB2, and the reactive mesogen polymer projections (RMP) can control and stabilize the pre-tilt angle of the liquid crystal compounds 301.

In the first liquid crystal aligning agents AA1, *—Y includes a nitrogen-containing hetero ring. The nitrogen-containing hetero ring can improve the spreadability of the first crystal aligning agents AA1 and the alignment stability of the liquid crystal compounds 301, as compared to a linear hydroxyl group and a linear amine group. In another embodiment, in the first liquid crystal aligning agents AA1, *—Y includes an oxygen-containing hetero ring. The oxygen-containing hetero ring can improve the spreadability of the first crystal aligning agents AA1 and the alignment stability of the liquid crystal compounds 301, compared to the linear hydroxyl group and the linear amine group. The first liquid crystal aligning agents AA1 can be uniformly adsorbed on the first electrode 180 and the second electrode 250. Since the liquid crystal display device 500 includes the first liquid crystal aligning agents AA1, edge alignment and alignment stability of the liquid crystal compounds 301 can be improved, as compared to an embodiment wherein *—Y in Formula 1-1 includes a linear hydroxyl group and a linear amine group as a liquid crystal aligning group. Further, the nitrogen-containing hetero ring and the oxygen-containing hetero ring can improve the voltage holding ratio of the liquid crystal display device 500, as compared to the linear hydroxyl group and the linear amine group.

The first liquid crystal aligning agent may contain at least one compound represented by Formulae SA 1-1 to SA 1-21 below.

As a non-restrictive example, the synthesis of a compound having the structure represented by Formula SA 1-20 will now be described.

First, 4-4′-dihydroxybiphenyl (1) and 3-hydroxytetrahydrofuran (2) are prepared. 4-4′-Dihydroxybiphenyl (1) and 3-hydroxytetrahydrofuran (2) are reacted with each other in the presence of tetrahydrofuran (THF), triphenylphosphine (PPh₃), and diethyl azodicarboxylate (N₂CO₂CHMe₂)₂ to prepare a compound of a structure represented by (3). The above reaction can be represented by, but not limited to, Reaction Formula 1-1.

Next, the compound of the structure represented by (3) is reacted with 1-bromodecane (4) in the presence of sodium hydroxide and tetrahydrofuran (THF) to prepare a compound of a structure represented by (5). The above reaction can be represented by, but not limited to, Reaction Formula 1-2 below.

Next, the compound of the structure represented by (5) is reacted with sodium bromide (NaBr) in the presence of dimethyldioxirane, sulfuric acid, and acetone to prepare a compound of a structure represented by (6). The above reaction can be represented by, but not limited to, Reaction Formula 1-3 below.

Next, the compound of the structure represented by (6) is reacted with ethylene oxide (7) in the presence of magnesium, iodine, hydrochloric acid, and tetrahydrofuran (THF) to prepare a compound of a structure represented by (8). The above reaction can be represented by, but not limited to, Reaction Formula 1-4 below.

Next, the compound of the structure represented by (8) is reacted with methacryloyl chloride (9) in the presence of tetraethylammonium (TEA) and methylene chloride (MC) to prepare a compound having the structure represented by Formula SA 1-20. The above reaction can be represented by, but not limited to, Reaction Formula 1-5 below.

In addition, the synthesis of a compound having the structure represented by Formula SA 1-21 will now be described.

First, 4-4′-dihydroxybiphenyl (1) and 2-(1,3-oxazolidin-3-yl) ethanol (2) are prepared.

Then, 4-4′-dihydroxybiphenyl (1) and 2-(1,3-oxazolidin-3-yl) are reacted with each other in the presence of tetrahydrofuran (THF), triphenylphosphine (PPh₃), and diethyl azodicarboxylate (N₂CO₂CHMe₂)₂ to prepare a compound of a structure represented by (3). The above reaction can be represented by, but not limited to, Reaction Formula 2-1 below.

Next, the compound of the structure represented by (3) is reacted with 1-bromodecane (4) in the presence of sodium hydroxide and tetrahydrofuran (THF) to prepare a compound of a structure represented by (5). The above reaction can be represented by, but not limited to, Reaction Formula 2-2 below.

Next, the compound of the structure represented by (5) is reacted with sodium bromide (NaBr) in the presence of dimethyldioxirane, sulfuric acid and acetone to prepare a compound having a structure represented by (6). The above reaction can be represented by, but not limited to, Reaction Formula 2-3 below.

Next, the compound of the structure represented by (6) is reacted with ethylene oxide (7) in the presence of magnesium, iodine, hydrochloric acid, and tetrahydrofuran (THF) to prepare a compound of a structure represented by (8). The above reaction can be represented by, but not limited to, Reaction Formula 2-4 below.

Next, the compound of the structure represented by (8) is reacted with methacryloyl chloride (9) in the presence of tetraethylammonium (TEA) and methylene chloride (MC) to prepare a compound having the structure represented by Formula SA 1-21. The above reaction can be represented by, but not limited to, Reaction Formula 2-5 below.

In FIGS. 3A through 3M, ¹H-NMR spectrums of the first liquid crystal aligning agents having the structures according to Formulas SA 1-9 to SA 1-21 are respectively illustrated. The ¹H-NMR spectrums were measured using Bruker Avance DPX-300 (at 300 MHz for ¹H NMR).

Although not shown in the drawings, the liquid crystal display device 500 may further include a color filter layer (not shown). The color filter layer (not shown) may be disposed at the region corresponding to each pixel PX in the display area I, and may include a red color filter (R), a green color filter (G), and a blue color filter (B). The color filter layer (not shown) may be included in any one of the display substrate SUB1 and the counter display substrate SUB2. For example, when the display substrate SUB1 includes the color filter layer, the display substrate SUB1 may have a color filter on array (COA) structure in which a first base substrate (not shown), a switching element (not shown), and a color filter layer (not shown) are sequentially laminated in this order. In this case, the first electrode 180 may be disposed on the color filter layer (not shown). Further, for example, when the counter display substrate SUB2 includes the color filter layer, the counter display substrate SUB2 may have a structure in which a second base substrate (not shown), a color filter layer (not shown), and an overcoat layer are sequentially laminated in this order. The overcoat layer (not shown) may be a planarization layer covering the color filter (not shown). In this case, the second electrode 250 may be disposed on the overcoat layer (not shown).

Although not shown in the drawings, the liquid crystal display device 500 may further include a backlight assembly (not shown) disposed at the rear side of the display substrate SUB1 to provide light to the liquid crystal layer 300.

The backlight assembly (not shown), for example, may include a light guide plate (not shown), a light source (not shown), a reflective member (not shown), and an optical sheet (not shown).

The light guide plate (not shown) serves to direct the light emitted from the light source toward the liquid crystal layer 300, and may include a light incoming surface configured to allow the light emitted from the light source (not shown) to be introduced, and a light outgoing surface configured to direct the emitted light toward the liquid crystal layer 300. The light guide plate may be made of a light-transmissive material, such as polymethylmethacrylate (PMMA) or polycarbonate (PC), which has a predetermined refractive index, but the present disclosure is not limited thereto. Since the light incoming upon one side or both sides of the light guide plate has an angle within the critical angle of the light guide plate, when the light is incident to the inside of the light guide plate and is incident to the upper surface or lower surface of the light guide plate, the incident angle of the light exceeds the critical angle of the light guide plate and thus the incident light is evenly delivered inside the light guide plate without being emitted to the outside of the light guide plate. A scattering pattern may be formed on any one of the upper surface and lower surface of the light guide plate in order to emit the guided light over the light guide plate. That is, a scattering pattern may be printed on the one surface of the light guide plate with ink such that the light delivered inside the light guide plate is emitted over the light guide plate. Such a scattering pattern may be formed by ink printing, but the present disclosure is not limited thereto. The light guide plate may be provided with minute grooves or protrusions, and may be modified as needed.

The reflective member (not shown) serves to reflect the light emitted to the lower surface of the light guide plate, that is, the surface facing the light outgoing surface, so as to supply the reflected light to the light guide plate. The reflective member may be in the form of a film, but the present disclosure is not limited thereto.

The light source (not shown) may be disposed to face the light incoming surface of the light guide plate. The number of light sources can be appropriately changed as needed. For example, one light source may be provided at only one side of the light guide plate, and three or more light sources corresponding to three or more sides of four sides of the light guide plate may also be provided. Meanwhile, a plurality of light sources corresponding to any one side of the light guide plate may also be provided. As described above, there has been exemplified a side-light type backlight assembly in which light sources are located at the sides of the light guide plate. However, in addition to this backlight assembly, a direct type backlight assembly, a planar light source type backlight assembly, and the like are exemplified according to the configuration of backlight. As the light source, a white light-emitting diode (LED) emitting white light, or a plurality of light-emitting diodes emitting red light, green light, and blue light, may be used. In the case where the plurality of light sources is composed of light-emitting diodes emitting red light, green light, and blue light, when these light-emitting diodes all turn on at once, white light can be realized as a result of the color mixing.

FIGS. 4A, 4B, and 4C are schematic cross-sectional views showing a process of manufacturing the liquid crystal display device 500 of FIG. 1.

Referring to FIGS. 4A and 4B, a liquid crystal composition including a liquid crystal compound 301, a first liquid crystal aligning agent AA1, and a reactive mesogen RM is injected or dropped between the display substrate SUB1 and the counter display substrate SUB2, so as to form a liquid crystal layer 300. Since the first liquid crystal aligning agent AA1 and the reactive mesogen RM have been described above, detailed descriptions thereof will be omitted. The liquid crystal layer 300, the display substrate SUB1, and the counter display substrate SUB2 together form a liquid crystal cell.

For example, the liquid crystal compound 301 may be a negative liquid crystal compound having negative dielectric anisotropy. In the early stage in which the liquid crystal composition is injected or dropped between the display substrate SUB1 and the counter display substrate SUB2, the liquid crystal compound 301 may be aligned in a direction substantially horizontal to the display substrate SUB1 and the counter display substrate SUB2. When a predetermined period of time has passed after the liquid crystal composition is injected or dropped between the display substrate SUB1 and the counter display substrate SUB2, the first liquid crystal aligning agents AA1 may be adsorbed on one surface of the first electrode 180 and one surface of the second electrode 250 to be self-aligned. At this time, the liquid crystal compounds 301 may be aligned in a direction substantially perpendicular to the display substrate SUB1 and to the counter display substrate SUB2.

Referring to FIGS. 4B and 4C, when a liquid crystal cell, in which the liquid crystal layer 300 is disposed between the display substrate SUB1 and the counter display substrate SUB2, is irradiated with ultraviolet light in a state where a voltage is applied to the liquid crystal cell, the liquid crystal compound 301 is aligned in a direction in which a major axis thereof is perpendicular to an electric field, and the reactive mesogen RM is photo-polymerized to form reactive mesogen polymer projections RMP. The reactive mesogen polymer projections are adsorbed on one surface of the first electrode 180 and on one surface of the second electrode 250 to provide a pre-tilt to the liquid crystal compounds 301 and to stabilize these liquid crystal compounds 301. Therefore, even when the voltage applied to the liquid crystal cell is released, the liquid crystal compounds 301 can be maintained in a pre-tilted state.

Referring to FIG. 2 and FIGS. 4A, 4B, and 4C, the method of manufacturing the liquid crystal display device 500 does not include a prior art liquid crystal alignment film forming process. For example, the method of manufacturing the liquid crystal display device 500 does not include the coating, drying, and sintering of an alignment solution. That is, in the method of manufacturing the liquid crystal display device 500, a prior art liquid crystal alignment film forming process can be omitted because both the liquid crystal compound 301 and the first liquid crystal aligning agent AA1 for aligning the liquid crystal compounds 301 are injected or dropped between the display substrate SUB1 and the counter display substrate SUB2 during the process of forming the liquid crystal layer 300. Therefore, the method of manufacturing the liquid crystal display device 500 can improve productivity or processability. Further, since the method of manufacturing the liquid crystal display device 500 does not use an organic solvent harmful to environment, this method is environmentally friendly, and can improve safety for workers. Moreover, since the method of manufacturing the liquid crystal display device 500 does not include a high-temperature sintering process, this method is advantageous in that it is easy to manufacture a liquid crystal display device using a flexible organic polymer substrate having many problems in a high-temperature process.

Meanwhile, the reactive mesogen polymer projections RMP can be formed in various forms depending on the content of the reactive mesogen RM, the photo-polymerization conditions, or the like.

FIGS. 5A and 5B are schematic cross-sectional views showing the modified embodiments of the liquid crystal display device 500 of FIG. 2. Hereinafter, differences between the liquid crystal display devices 500, 500-1, and 500-2 will be described with reference to FIG. 2 and FIGS. 5A and 5B.

The liquid crystal display device 500-1 may be configured such that a reactive mesogen polymer layer RML is further formed around reactive mesogen polymer projections

RMP. The reactive mesogen polymer projections RMP are formed so as to protrude from the reactive mesogen polymer layer RML. At this point, the liquid crystal display device 500-1 is different from the liquid crystal display device 500. The liquid crystal display device 500-2 is configured such that first liquid crystal aligning agents AA1 are covered with a reactive mesogen polymer layer RML and the reactive mesogen polymer projections RMP protrude from the reactive mesogen polymer layer RML. At this point, the liquid crystal display device 500-2 is different from the liquid crystal display device 500.

FIG. 6 is a schematic cross-sectional view of a liquid crystal display device 501 according to another embodiment of the present disclosure.

Referring to FIG. 6, the liquid crystal display device 501 can align the liquid crystal compound using a polymer of two or more second liquid crystal aligning agents AA2 represented by Formula 1-2 below. The polymers of the second liquid crystal aligning agent AA2 represented by Formula 1-2 below may be adsorbed on the surface of at least one of the first electrode 180 and the second electrode 250.

In Formula 1-2, X″—*, which is a polymerizing group of the second liquid crystal aligning agent AA2, may be

In Formula 1-2, *-L₁-*, which is a linking group, may be a single bond, *—(CH₂)_p1—*, *—O(CH₂)_p1—*, *—O—*,

*—CH═CH—*, or *—C≡C—* Here, p1 may be an integer of 1 to 10.

In Formula 1-2, *-L₂-*, which is a linking group, may be a single bond, *—(CH₂)_p2—*, *—O(CH₂)_p2—*, *—O—*,

*—CH═CH—*, or *—C≡C—*. Here, p2 may be an integer of 1 to 10.

In Formula 1-2, *-L₃-*, which is a linking group, may be a single bond, *—(CH₂)_p3—*, *—O(CH₂)_p3—*, *—O—*,

*—CH═CH—*, or *—C≡C—*. Here, p3 may be an integer of 1 to 10.

*-L₁-*, *-L₂-*, and *-L₃-* may be identical to, or different from, one another.

In Formula 1-2, *—R—*, which is a spacer for maintaining the length of the second liquid crystal aligning agents AA2 in a long chain direction, may be *—(CH₂)_q—*, *—O(CH₂)_q—*, *—(CH₂)_qArn-*, or *—O(CH₂)_qArn-*. Am may be a substituted or unsubstituted C_6-30 arylene, and q is an integer of 1 to 10. The substituted C_6-30 arylene is an arylene in which at least one hydrogen group is substituted with a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or a C_1-10-((meth)acryloxy)alkyl-*. In Formula 1-2, n₁ may be an integer of 1 to 3, and n₂ and m may each independently 0 or 1.

In Formula 1-2, *—C—*, which is a functional group for improving the miscibility of the second liquid crystal aligning agent AA2 with the liquid crystal compound 301, is a substituted or unsubstituted cyclic linking group. In Formula 1-2, *—C—* may be substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

substituted or unsubstituted

or substituted or unsubstituted

The substituted cyclic linking group is a cyclic linking group in which at least one hydrogen group (H—*) is substituted or unsubstituted with a C_1-10-alkyl-*, F—*, Br—*, I—*, *—OH, *—NH₂, or a C_1-10-((meth)acryloxy)alkyl-*.

In Formula 1-2, *—Y, which is a monovalent atomic group including a hetero ring, may be a functional group for improving the adsorption of the second liquid crystal aligning agent AA2 to at least one of the first electrode 180 and the second electrode 250. For example, *—Y may be a C₂-C₃₀ monovalent atomic group including one or more C₂-C₅ heterocyclic structures having a nitrogen atom and/or an oxygen atom in a hetero ring. The hetero ring having the nitrogen atom and/or the oxygen atom may be substituted or unsubstituted.

In an exemplary embodiment, in Formula 1-2, *—Y may be

Here, n may be 0 to 5.

The polymers of the second liquid crystal aligning agents AA2 are configured to include a vertical aligning group B for aligning the liquid crystal compounds 301 in a direction substantially perpendicular to at least one of the display substrate SUB1 and the counter display substrate SUB2, and a reactive mesogen RM as a photo-polymerizable functional group that can be photo-polymerized by ultraviolet light. The reactive mesogen RM is polymerized to form a polymer network for controlling and stabilizing the pre-tilt angle of the liquid crystal compounds 301.

In the second liquid crystal aligning agents AA2, *—Y includes a nitrogen-containing hetero ring. The nitrogen-containing hetero ring can improve the spreadability of the second crystal aligning agents AA2 and the alignment stability of the liquid crystal compounds 301, as compared to a linear hydroxyl group and a linear amine group. In another embodiment, in the second liquid crystal aligning agent AA2, *—Y includes an oxygen-containing hetero ring. The oxygen-containing hetero ring can improve the spreadability of the second crystal aligning agent AA2 and the alignment stability of the liquid crystal compound 301, as compared to the linear hydroxyl group and the linear amine group. The second liquid crystal aligning agent AA2 can be uniformly adsorbed on the first electrode 180 and the second electrode 250. Since the liquid crystal display device 500 includes the second liquid crystal aligning agent AA2, edge alignment and alignment stability of the liquid crystal compound 301 can be improved, compared to an embodiment wherein *—Y in Formula 1-2 includes a linear hydroxyl group and a linear amine group as a liquid crystal aligning agent. Further, the nitrogen-containing hetero ring and the oxygen-containing hetero ring can improve the voltage holding ratio of the liquid crystal display device 500, as compared to the linear hydroxyl group and the linear amine group.

The second liquid crystal aligning agent may contain at least one compound represented by Formulae SA 2-1 to SA 2-17 below.

In FIGS. 7A through 7C, ¹H-NMR spectrums of the second liquid crystal aligning agents according to Formulas SA 2-15 to SA 2-17 are respectively illustrated. The ¹H-NMR spectrums were measured using Bruker Avarice DPX-300 (at 300 MHz for ¹H NMR).

FIGS. 8A, 8B, and 8C are schematic cross-sectional views showing a process of manufacturing the liquid crystal display device 501 of FIG. 6.

Referring to FIGS. 8A and 8B, a liquid crystal composition including the liquid crystal compound 301 and the second liquid crystal aligning agent AA2 is disposed, for example, injected or dropped, between the display substrate SUB1 and the counter display substrate SUB2, so as to form a liquid crystal layer 300. Since the second liquid crystal aligning agent AA2 is described above, an additional detailed description thereof will be omitted. For example, the liquid crystal compounds 301 may be negative liquid crystal compounds having negative dielectric anisotropy. In the early stage in which the liquid crystal composition is disposed, for example, injected or dropped, between the display substrate SUB1 and the counter display substrate SUB2, the liquid crystal compound 301 may be aligned in a direction substantially horizontal to the display substrate SUB1 and the counter display substrate SUB2. Once a predetermined period of time has passed after the liquid crystal composition is disposed between the display substrate SUB1 and the counter display substrate SUB2, the second liquid crystal aligning agent AA2 may be adsorbed on one surface of the first electrode 180 and on one surface of the second electrode 250 to be self-aligned. At this time, the liquid crystal compound 301 may be aligned in a direction substantially perpendicular to the display substrate SUB1 and the counter display substrate SUB2.

Referring to FIGS. 8B and 8C, when a liquid crystal cell, in which the liquid crystal layer 300 is disposed between the display substrate SUB1 and the counter display substrate SUB2, is irradiated with ultraviolet light in a state where a voltage is applied to the liquid crystal cell, the liquid crystal compound 301 is aligned in a direction in which a major axis thereof is perpendicular to an electric field, reactive mesogen RM (i.e., photo-polymerization reaction group) is photo-polymerized, and thus the second liquid crystal aligning agents AA2 can form a polymer network for controlling and stabilizing the pre-tilt angle of the liquid crystal compound 301. Therefore, even when the voltage applied to the liquid crystal cell is released, the liquid crystal compound 301 can be maintained in a pre-tilted state.

Referring to FIG. 6 and FIGS. 8A, 8B, and 8C, the method of manufacturing the liquid crystal display device 501 does not include a conventional liquid crystal alignment film forming process (for example, coating, drying, and sintering of an alignment solution. That is, in the method of manufacturing the liquid crystal display device 501, a conventional liquid crystal alignment film forming process can be omitted because both the liquid crystal compound 301 and the second liquid crystal aligning agent AA2 for aligning the liquid crystal compound 301 are injected or dropped between the display substrate SUB1 and the counter display substrate SUB2 in the process of forming the liquid crystal layer 300. Therefore, the method of manufacturing the liquid crystal display device 501 can improve productivity or processability. Further, since the method of manufacturing the liquid crystal display device 501 does not use an organic solvent harmful to the health of an individual or harmful to the environment, the method is environmentally friendly, and can improve safety for workers. Moreover, since the method of manufacturing the liquid crystal display device 501 does not include a high-temperature sintering process, this method is advantageous in that it is easy to manufacture a liquid crystal display device including a flexible organic polymer substrate, which is susceptible to many problems when subjected to a high-temperature process.

Referring to FIGS. 4A, 4B, and 4C and FIGS. 8A, 8B, and 8C, unlike the method of manufacturing the liquid crystal display device 500, the method of manufacturing the liquid crystal display device 501 does not include the reactive mesogen RM. The reason for this is that the second liquid crystal aligning agent AA2 includes the photo-polymerization reaction groups. Therefore, in the method of manufacturing the liquid crystal display device 501, the liquid crystal composition does not contain the reactive mesogen RM represented by Formula 2 above. Similarly, in the liquid crystal display device 501, the liquid crystal layer 300 does not contain the reactive mesogen RM represented by Formula 2 above. That is, in the liquid crystal display device 501, the content of the reactive mesogen RM represented by Formula 2 is 0 percent by weight (wt %), based on a total weight of the liquid crystal composition or based on a total weight of the liquid crystal layer.

Hereinafter, the method of manufacturing a liquid crystal display device according to the present disclosure will be summarized. The method of manufacturing a liquid crystal display device according to the present disclosure includes the steps of:

disposing (for example, injecting or dropping) a liquid crystal composition including a liquid crystal compound and at least one liquid crystal aligning agent represented by Formula 1 above between a first electrode and a second electrode facing the first electrode to manufacture a liquid crystal cell; and

irradiating the liquid crystal cell with ultraviolet rays when a voltage is applied to the liquid crystal cell.

The liquid crystal aligning agent may be a first liquid crystal aligning agent including at least one compound represented by Formula 1-1 above. In this case, the liquid crystal composition may further contain a reactive mesogen represented by Formula 2 above.

The liquid crystal aligning agent may be a second liquid crystal aligning agent containing at least one compound represented by Formula 1-2 above. In this case, the content of the reactive mesogen represented by Formula 2 above in the liquid crystal composition may be 0 wt %, based on a total weight of the liquid crystal composition.

Hereinafter, effects of a liquid crystal display device according to the present disclosure will be described in detail by way of specific Examples and Comparative Examples.

Example 1: Preparation of a Liquid Crystal Aligning Agent Having the Structure Represented by Formula SA 1-21

(5.4 mmol) of 4,4′-dihydroxybiphenyl was added to 100 mL of tetrahydrofuran (THF) and stirred. 0.54 mmol of triphenylphosphine was added to the stirred solution, and the mixture was stirred and cooled to a temperature of 0° C. using an ice bath. After 0.54 mmol of diethyl azodicarboxylate was added, 5.4 mmol of 2-(1,3-oxazolidin-3-yl) ethanol was added, which was followed by stirring at a temperature of 20° C. for 18 hours. The stirred solution was filtered using a filter paper, and the solvent was removed. Then, a compound (3) was obtained by purification through recrystallization using 100 nil of ethyl acetate.

100 mL of tetrahydrofuran was added to 5.0 mmol of the purified compound (3) and stirred. 6.5 mmol of sodium hydroxide was added to the stirred solution. After 6.5 mmol of 1-bromodecane was added, the mixture was refluxed for 24 hours, and then the reaction salt was removed using a filter paper. After removal of the solvent, a compound (5) was obtained by purification through recrystallization using 100 mL of ethyl acetate.

100 ml of acetone was added to the purified compound (5) and stirred. 11.0 mmol of sodium bromide, 11.0 mmol of dimethyldioxane and 11.0 mmol of sulfuric acid were added to the solution being stirred, and the mixture was stirred at room temperature. After the reaction salt was removed using a filter paper, a compound (6) was obtained by purification through recrystallization using 100 mL of ethyl acetate.

100 mL of tetrahydrofuran was added to 4.5 mmol of the purified compound (6) and stirred. After 10.0 mmol of magnesium and 10.0 mmol of iodine were added to the solution being stirred, the mixture was refluxed for 4 hours. The solution being refluxed was cooled using an ice bath, 10.0 mmol of ethylene oxide was added to the solution, and the mixture was stirred for 24 hours. 10.0 mmol of hydrochloric acid was added to the stirred solution, and the mixture was stirred for 1 hour. Then, the reaction salt was removed using a filter paper. After removal of the solvent, a compound (8) was obtained by purification through recrystallization using 100 ml of ethyl acetate.

10.0 mmol of methacrylic acid was added to 50 mL of methylene chloride and stirred. 10.0 mmol of thionyl chloride was added to the solution being stirred, and the mixture was stirred for an additional 3 hours. After 10.0 mmol of triethylamine and 4.0 mmol of the purified compound (8) were added to the stirred solution, the mixture was Stirred at room temperature for 24 hours. Then, the reaction salt was removed using a filter paper, and the solvent was dried. Finally, a compound having the structure represented by Formula SA 1-21 was obtained through recrystallization using 100 mL of ethyl acetate.

Example 2-1: Preparation of a Liquid Crystal Aligning Agent Having the Structure Represented by Formula SA 2-4

A liquid crystal display device 501 was manufactured as shown in FIGS. 8A, 8B, and 8C, and a compound represented by Formula SA 2-4 below was used as a liquid crystal aligning agent. In addition, images of the liquid crystal display device 501, that is, images of a liquid crystal display device according to Example 2-1 are shown in FIGS. 9A and 9B.

Example 2-2: Manufacture of a Liquid Crystal Display Device Using a Liquid Crystal Aligning Agent Having the Structure Represented by Formula SA 1-9

A liquid crystal display device was manufactured as shown in FIGS. 4A, 4B and 4C, and a compound represented by Formula SA 1-9 below was used as a liquid crystal aligning agent. In addition, images of a liquid crystal display device according to Example 2-2 are shown in FIGS. 10A through 10D.

Example 2-3: Manufacture of a Liquid Crystal Display Device Using a Liquid Crystal Aligning Agent Having the Structure Represented by Formula SA 1-2

A liquid crystal display device was manufactured as shown in FIGS. 4A, 4B and 4C, and a compound represented by Formula SA 1-2 below was used as a liquid crystal aligning agent. In addition, the voltage holding ratio of a liquid crystal display device according to Example 2-3 was measured, and the measurement results are shown in Table 1 below

Example 2-4: Manufacture of a Liquid Crystal Display Device Using a Liquid Crystal Aligning Agent Having the Structure Represented by Formula SA 1-20

A liquid crystal display device was manufactured as shown in FIGS. 4A, 4B and 4C, and a compound represented by Formula SA 1-20 below was used as a liquid crystal aligning agent. In addition, the voltage holding ratio of a liquid crystal display device according to Example 2-4 with respect to the UV irradiating time was measured, and the measurement results are shown in Table 1 below.

Comparative Example 1: Manufacture of a Liquid Crystal Display Device Using a Liquid Crystal Aligning Agent Having a Structure Represented by Formula C1

A liquid crystal display device was manufactured as shown in FIGS. 8A, 8B and 8C, and a compound represented by Formula C1 below was used as a liquid crystal aligning agent. In addition, images of a liquid crystal display device according to Comparative Example 1 are shown in FIGS. 12A and 12B.

Comparative Example 2: Manufacture of a Liquid Crystal Display Device Using a Liquid Crystal Aligning Agent Having a Structure Represented by Formula C2

A liquid crystal display device was manufactured using the process illustrated in FIGS. 4A, 4B, and 4C, and a compound represented by Formula C2 below was used as a liquid crystal aligning agent. In addition, the voltage holding ratio of a liquid crystal display device according to Comparative Example 2 was measured, and the measurement results are shown in Table 1 below.

FIGS. 9A and 9B show images of a liquid crystal display device according to Example 2-1. FIGS. 12A and 12B show images of a liquid crystal display device according to Comparative Example 1.

Referring to FIGS. 9A and 12A, in the liquid crystal display device 501 of Example 2-1, edge alignment was improved compared to in the liquid crystal display device of Comparative Example 1. Without being limited by theory, the reason for this is that the compound represented by Formula SA 2-4 includes a heterocyclic structure, specifically, a nitrogen-containing hetero ring and thus can be stably adsorbed on the substrate surface. In addition, the nitrogen-containing hetero ring can improve the spreadability of the liquid crystal aligning agent compared to a linear hydroxyl group.

Comparing the alignment stability of the liquid crystal display device 501 of Example 2-1 with the alignment stability of the liquid crystal display device of Comparative Example 1 after exposing the liquid crystal display devices to a temperature of 60° C. for 1,000 hours, the edge alignment of the liquid crystal display device 501 of Example 2-1 was improved compared to that of the liquid crystal display device of Comparative Example 1 (see FIGS. 9B and 12B). Without being limited by theory, it is believed that the reason for this is because the compound represented by Formula SA 2-4 includes a heterocyclic structure, specifically, a nitrogen-containing hetero ring and thus can be stably adsorbed on the substrate surface. In addition, the nitrogen-containing hetero ring can stabilize the alignment of liquid crystal aligning agents 301, as compared to a linear hydroxyl group.

FIG. 10A shows an image of a liquid crystal display device of Example 2-2 at a black gradation level, and FIG. 10B shows an image of the liquid crystal display device of Example 2-2 at a gray gradation level.

Referring to FIG. 10A, the liquid crystal display of Example 2-2 displays intact black without the leakage of light at a black gradation level at which no voltage is applied between a pixel electrode and a common electrode. In addition, referring to FIG. 10B, the liquid crystal display device of Example 2-2 displays gray through transmission of light at a gray gradation level at which a predetermined voltage is applied between the pixel electrode and the common electrode.

That is, in the liquid crystal display device of Example 2-2, the liquid crystals can be aligned substantially vertically at least one of a display substrate and a counter display substrate even in the absence of an alignment film and can be rearranged as an electric field is formed between field generating electrodes. Without being limited by theory, it is believed this is because the compound represented by Formula SA 1-9 above includes a heterocyclic structure, specifically, an oxygen-containing hetero ring, and thus can be stably adsorbed on the substrate surface.

FIG. 10C shows an electron microscope (SEM) image of the surface of the pixel electrode of the liquid crystal display device of Example 2-2, and FIG. 101) shows an SEM image of the exposed film surface without being covered by the pixel electrode of the liquid crystal display device of Example 2-2.

Referring to FIGS. 10C and 10D, a liquid crystal aligning agent having the structure represented by Formula SA 1-9 and reactive mesogen are stably aligned on the surface of the pixel electrode and the film surface to form projection structures.

FIG. 11 is a graph illustrating the voltage holding ratio versus the ultraviolet (UV) light irradiating time of the liquid crystal display device of Example 2-4.

Referring FIG. 11, it can be seen that the liquid crystal display device of Example 2-4 has a sufficient voltage holding ratio only after UV light is irradiated to remove the remaining unreacted reactive mesogens, but also before the UV light is irradiated.

	TABLE 1
	Voltage holding ratio (%)
	Before	After	After fluorescent
	exposure	UV exposure	UV exposure
Comparative Example 2	98.9	99.0	99.2
Example 2-3	98.9	99.1	99.3

Referring to Table 1 above, it can be ascertained that the voltage hold ratio of Example 2-3 is higher than that of Comparative Example 2.

Although the preferred embodiments of the present disclosure have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions, and substitutions are possible, without departing from the scope and spirit of the present disclosure as recited in the accompanying claims.

Claims

1. A liquid crystal composition, comprising: a liquid crystal compound; anda liquid crystal aligning agent comprising at least one compound represented by Formula 1:

2. The liquid crystal composition of claim 1, wherein X—* is a C1-20-alkyl-*, andwherein the liquid crystal composition further comprises a reactive mesogen comprising at least one compound represented by Formula 2: P1-SP1-MG-SP2-P2  Formula 2wherein in Formula 2,P1-* and *—P2 are each independently

3. The liquid crystal composition of claim 2, wherein the liquid crystal aligning agent comprises at least one compound represented by Formulae SA 1-1 to SA 1-21:

4. The liquid crystal composition of claim 1, wherein the liquid crystal aligning agent comprises the compound represented by Formula 1,wherein X—* is

5. The liquid crystal composition of claim 4, wherein the liquid crystal aligning agent comprises at least one compound represented by Formulae SA 2-1 to SA 2-17:

6. A liquid crystal display device, comprising: a first electrode;a second electrode facing the first electrode;a liquid crystal layer comprising a liquid crystal compound, wherein the liquid crystal layer is disposed between the first electrode and the second electrode;a liquid crystal aligning agent comprising at least one compound represented by Formula 1-1, wherein the liquid crystal layer is adsorbed on a surface of at least one of the first electrode and the second electrode to align the liquid crystal compound; anda polymer of reactive mesogen comprising two or more compounds represented by Formula 2, wherein the polymer of reactive mesogen is adsorbed on the surface of at least one of the first electrode and the second electrode to align the liquid crystal compound:

7. The liquid crystal display device of claim 6, wherein the liquid crystal aligning agent comprises at least one compound represented by Formulae SA 1-1 to SA 1-21:

8. A liquid crystal display device, comprising: a first electrode;a second electrode facing the first electrode;a liquid crystal layer comprising a liquid crystal compound, wherein the liquid crystal layer is disposed between the first electrode and the second electrode; anda polymer of a liquid crystal aligning agent comprising two or more compounds represented by Formula 1-2, wherein the polymer of liquid crystal aligning agent is adsorbed on a surface of at least one of the first electrode and the second electrode to align the liquid crystal compound,wherein the liquid crystal layer does not contain a compound represented by Formula 2:

9. The liquid crystal display device of claim 8, wherein the liquid crystal aligning agent comprises at least one compound represented by Formulae SA 2-1 to SA 2-17:

10. A method of manufacturing a liquid crystal display device, comprising: disposing the liquid crystal composition of claim 1 between a first electrode and a second electrode facing the first electrode to manufacture a liquid crystal cell; andirradiating the liquid crystal cell with ultraviolet light while applying a voltage to the liquid crystal cell.

11. The method of claim 10, wherein the liquid crystal aligning agent comprises the compound represented by Formula 1, wherein in Formula 1 X—* is a C1-20-alkyl-*, andwherein the liquid crystal composition further comprises a reactive mesogen comprising at least one compound represented by Formula 2: P1-SP1-MG-SP2-P2  Formula 2wherein in Formula 2,P1-* and *—P2 are each independently

12. The method of claim 11, wherein the liquid crystal aligning agent comprises at least one compound represented by Formulae SA 1-1 to SA 1-21:

13. The method of claim 10, wherein the liquid crystal aligning agent comprises the compound represented by Formula 1, wherein X—* is

14. The method of claim 13, wherein the liquid crystal aligning agent comprises at least one compound represented by Formulae SA 2-1 to SA 2-17: