KR101675936B1

KR101675936B1 - Liquid crystal alignment layer comprising amphiphilic block copolymer, liquid crystal display device using the same and method for manufacturing the same

Info

Publication number: KR101675936B1
Application number: KR1020150045559A
Authority: KR
Inventors: 이준협; 손인태; 김재홍
Original assignee: 명지대학교 산학협력단
Priority date: 2015-03-31
Filing date: 2015-03-31
Publication date: 2016-11-14
Also published as: KR20160117014A

Abstract

The present invention relates to a TFT array substrate; A color filter substrate; And a liquid crystal layer interposed between the array substrate and the color filter substrate, wherein the liquid crystal layer includes a liquid crystal and a liquid crystal alignment layer, wherein the liquid crystal alignment layer comprises at least one hydrophobic unit and at least one hydrophilic And an amphiphilic block copolymer comprising a unit of the amphiphilic block copolymer.
Therefore, the liquid crystal alignment layer including the amphiphilic block copolymer according to the present invention, the liquid crystal display using the same, and the method of manufacturing the same can realize alignment of liquid crystal molecules and excellent electro-optical characteristics without the conventional polyimide alignment layer.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal alignment layer including an amphiphilic block copolymer, a liquid crystal display using the same,

The present invention relates to a liquid crystal alignment layer including an amphiphilic block copolymer, a liquid crystal display using the same, and a method of manufacturing the same. More particularly, the present invention relates to a liquid crystal alignment layer comprising a liquid crystal alignment layer used for aligning liquid crystal molecules A liquid crystal display using the same, and a method of manufacturing the same.

2. Description of the Related Art A liquid crystal display (LCD) is composed of a liquid crystal display device that displays an image using light transmittance of a liquid crystal and a backlight assembly that provides light. The liquid crystal display device generally includes a TFT array substrate, a color filter layer substrate facing the array substrate, and a liquid crystal layer interposed between the array substrate and the color filter layer substrate. When an electric field is applied to the liquid crystal layer, the arrangement of the liquid crystal molecules changes according to an electric field formed thereby, and a phase difference of incident light passing through the liquid crystal layer is generated, and light is transmitted to display an image.

In general, an alignment film polymer layer is used to form an initial alignment of liquid crystal molecules in a state where a voltage is not supplied to a display device. Generally, polyimide-based polymers are mainly used, and the polymer solution is printed on the array and the color filter layer substrate in the form of a thin film before the injection of the liquid crystal, followed by heat treatment and firing.

However, the conventional alignment film process requires a separate thin film forming step before liquid crystal injection, and the thin film is subjected to a multi-step drying and curing process, which complicates and takes a long time. Further, unevenness in the thickness of the thin film caused problems such as unevenness.

Korean Patent No. 10-0484851 Korean Patent No. 10-0782436 Korean Patent No. 10-1046926

The present invention provides a low-cost and high-speed response liquid crystal display device that realizes display characteristics using an amphiphilic block copolymer without a polyimide alignment layer and a method of manufacturing the same, and provides a liquid crystal alignment layer And the like.

The present invention relates to a TFT array substrate, A color filter substrate; And a liquid crystal layer interposed between the array substrate and the color filter substrate, wherein the liquid crystal layer includes a liquid crystal and a liquid crystal alignment layer, wherein the liquid crystal alignment layer comprises at least one hydrophobic unit and at least one hydrophilic And an amphiphilic block copolymer comprising a unit of the amphiphilic block copolymer.

The hydrophobic unit

or

(10? M? 40), and the hydrophilic unit is selected from the group consisting of

or

(1? N? 30).

Also, it can be represented by the following formula (1).

[Chemical Formula 1]

In Formula 1, a is a hydrophobic unit and b is a hydrophilic unit.

The hydrophilic unit may be contained in an amount of 10 to 70 parts by weight based on 100 parts by weight of the amphiphilic block copolymer. When mixed at 10 to 70 parts by weight, a homogeneous self-assembled liquid crystal alignment layer is formed, so that the black screen display capability is excellent, and excellent gradation display of liquid crystal is possible.

Preferably the amphiphilic block copolymer is selected from the group consisting of polyethylene block-polyethylene glycol, polyethylene block-polypropylene glycol, polypropylene block-polyethylene glycol, polypropylene block-polypropylene glycol, polyethylene block- At least one selected from the group consisting of polyethylene, polyethylene-block-polypropylene glycol-block-polyethylene, polyethylene glycol-block-polyethylene-block-polyethylene glycol and polypropylene glycol-block-polyethylene-block-polypropylene glycol .

The present invention relates to a TFT array substrate, A color filter substrate; And a liquid crystal layer interposed between the array substrate and the color filter substrate, wherein the amphiphilic block copolymer comprises at least one hydrophobic unit and at least one hydrophilic unit, Preparing a block copolymer-liquid crystal mixture; Dropping the mixture on one side of at least one of the array substrate and the color filter substrate; Attaching the two substrates such that the mixture is positioned between the array substrate and the color filter substrate; And a step of heat treating the bonded substrate and cooling to room temperature.

The hydrophobic unit

or

(10? M? 40), and the hydrophilic unit is selected from the group consisting of

or

(1? N? 30).

Also, it can be represented by the following formula (1).

[Chemical Formula 1]

In Formula 1, a is a hydrophobic unit and b is a hydrophilic unit.

The amphiphilic block copolymer may be added in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the liquid crystal. When mixed at 0.01 to 10 parts by weight, there is an effect that a homogeneous self-assembled liquid crystal alignment layer showing a black screen without defects of light gaps can be formed by phase separation.

The heat treatment may be performed at a temperature of 80 to 120 DEG C for 30 to 120 minutes.

The present invention also provides a liquid crystal alignment layer comprising an amphiphilic block copolymer comprising a compound represented by the following formula (1) as a liquid crystal alignment layer used in a liquid crystal display element.

The hydrophobic unit

or

(10? M? 40), and the hydrophilic unit is selected from the group consisting of

or

(1? N? 30).

Also, it can be represented by the following formula (1).

[Chemical Formula 1]

In Formula 1, a is a hydrophobic unit and b is a hydrophilic unit.

The liquid crystal alignment layer including the amphiphilic block copolymer according to the present invention, the liquid crystal display using the same, and the method of manufacturing the same can realize alignment of liquid crystal molecules and excellent electrooptical properties without a conventional polyimide alignment layer.

1 is a schematic view of a liquid crystal display according to an embodiment of the present invention.
FIG. 2 is an image showing black screen magnitude of a liquid crystal display element (embodiment and comparative example) in which no voltage is applied in a state that the backlight is turned on.
FIG. 3 is a graph showing a voltage-transmittance curve according to voltages of Examples and Comparative Examples.
4 is a graph showing the contact angle of the alignment surface formed by the ITO transparent electrode and the amphiphilic block copolymer according to the physical properties and the concentration of the amphiphilic block copolymer.

Hereinafter, the present invention will be described in detail by way of examples. The objects, features and advantages of the present invention will be readily understood through the following drawings and examples. The present invention is not limited to the drawings and embodiments described herein, but may be embodied in other forms. The drawings and embodiments are provided so that those skilled in the art can fully understand the spirit of the present invention. therefore. The scope of the present invention should not be limited by the following drawings and examples.

The liquid crystal display 100 of the present invention will be described with reference to FIG. The liquid crystal display element 100 includes a liquid crystal layer between the color filter substrate 110 and the TFT array substrate 120. A liquid crystal alignment layer including an amphiphilic block copolymer 140 is formed between the substrates 110 and 120 of the liquid crystal display element 100. [ The amphiphilic block copolymer 140 has a hydrophobic unit 142 that interacts with the liquid crystal 130 of the liquid crystal layer at one end and a hydrophilic unit 141 that bonds to the substrate at the other end. The hydrophobic unit 142 of the amphiphilic block copolymer 140 interacts with the liquid crystal molecules of the liquid crystal layer to vertically align the liquid crystal molecules and the hydrophilic unit 141 makes a hydrogen bond with the ITO electrode or glass of the substrate Thereby causing the amphiphilic block copolymer 140 to be fixed to the substrate.

< Example 1> Liquid Crystal Display Device Manufacturing 1 - PEG 20 Weight portion , 0.1 Weight portion

Polyethylene-block-polyethylene glycol (PE-B-PEG), which is an amphiphilic block copolymer capable of noncovalent bonding, was added to a host liquid crystal having a dielectric anisotropy (DELTA epsilon) of 3.3. The polyethylene glycol was 20 parts by weight based on 100 parts by weight of the polyethylene-block-polyethylene glycol, and 0.1 part by weight with respect to 100 parts by weight of the liquid crystal was added to the amphiphilic block copolymer. Then, the mixture was stirred at 70 ° C for about 10 minutes to allow the amphiphilic block copolymer to completely dissolve and mix in the host liquid crystal.

Next, an amorphous block copolymer-liquid crystal mixture was evenly dropped on a lower TFT array substrate having a pixel electrode (ITO) or an upper color filter substrate having a common electrode (common ITO), and the two substrates were sealed with a sealant Respectively. After the cementation, the liquid crystal display cell was heat-treated in a high-temperature oven at a temperature of 100 ° C for about 1 hour and then cooled to room temperature so that the amphiphilic block copolymers were allowed to noncovalently bond with the substrate, So that a liquid crystal alignment layer was formed to produce a liquid crystal display device.

&Lt; Example 2 > Preparation of Liquid Crystal Display Device 2 - 20 parts by weight of PEG, 0.05 parts by weight

Polyethylene-block-polyethylene glycol (PE-B-PEG), which is an amphiphilic block copolymer capable of noncovalent bonding, was added to a host liquid crystal having a dielectric anisotropy (DELTA epsilon) of 3.3. At this time, polyethylene glycol was 20 parts by weight based on 100 parts by weight of polyethylene-block-polyethylene glycol, and 0.05 parts by weight with respect to 100 parts by weight of liquid crystal was added to the amphiphilic block copolymer. Then, the mixture was stirred at 70 ° C for about 10 minutes to allow the amphiphilic block copolymer to completely dissolve and mix in the host liquid crystal.

< Example 3> Liquid Crystal Display Device Manufacturing 3 - PEG 50 Weight portion , 0.05 Weight portion

Polyethylene-block-polyeth ylene glycol (PE-B-PEG) as an amphiphilic block copolymer capable of noncovalent bonding to a host liquid crystal having a dielectric anisotropy (DELTA epsilon) of 3.3 was added. At this time, polyethylene glycol was 50 parts by weight based on 100 parts by weight of the polyethylene-block-polyethylene glycol, and 0.05 parts by weight with respect to 100 parts by weight of the liquid crystal was added to the amphiphilic block copolymer. Then, the mixture was stirred at 70 ° C for about 10 minutes to allow the amphiphilic block copolymer to completely dissolve and mix in the host liquid crystal.

< Example 4> Manufacture of liquid crystal display devices 4 - PEG 50 Weight portion , 0.1 Weight portion

Polyethylene-block-polyeth ylene glycol (PE-B-PEG) as an amphiphilic block copolymer capable of noncovalent bonding to a host liquid crystal having a dielectric anisotropy (DELTA epsilon) of 3.3 was added. At this time, polyethylene glycol was 50 parts by weight based on 100 parts by weight of polyethylene-block-polyethylene glycol, and 0.1 parts by weight with respect to 100 parts by weight of the liquid crystal was added to the amphiphilic block copolymer. Then, the mixture was stirred at 70 ° C for about 10 minutes to allow the amphiphilic block copolymer to completely dissolve and mix in the host liquid crystal.

< Comparative Example >

A polyimide-based alignment film was applied to a lower TFT array substrate having a pixel electrode (ITO) or an upper color filter substrate having a common electrode (common ITO), and then the two substrates were bonded together using a sealant. After the liquid crystal was injected after the cementation, the liquid crystal display cell was heat-treated in a high-temperature oven at 100 ° C for about 1 hour and then cooled to room temperature to prepare a liquid crystal display device.

< Experimental Example 1> Orientation force And electro-optical characteristic analysis

The alignment properties and the electro-optical properties of the liquid crystal display device prepared according to the examples were measured. As a result of comparing the degree of black display on the OV in which the voltage was not applied to the liquid crystal device, the liquid crystal display cell according to the embodiment realized a black screen without light leakage throughout the screen 2).

Also, the alignment state of the liquid crystal was confirmed through a polarizing microscope (BXP 51, Olympus). As a result, the liquid crystal display cell according to the example exhibited a vertical alignment force equal to that of the liquid crystal display cell (comparative example) to which the conventional polyimide alignment film was applied .

As a result of measurement of a voltage-transmittance curve according to a voltage, a VT characteristic similar to that of a conventional liquid crystal display cell (comparative example) was exhibited, and it was possible to express a gray scale according to a voltage (see FIG. 3) .

< Experimental Example 2> Contact angle analysis

As a result of examining the contact angle of the alignment surface formed by noncovalently bonding the amphiphilic block copolymer with the ITO transparent electrode according to the physical properties and concentration of the block copolymer, it was found that 20 parts by weight of the minimum PEG and 0.05 parts by weight or less of the amphiphilic block copolymer It was confirmed that a self-assembled liquid crystal alignment layer was formed (see FIGS. 4 and 5).

100: liquid crystal display element
110: color filter substrate 111: substrate
112: color filter 113: common electrode
120: TFT array substrate 121: substrate
122: insulating film 123: pixel electrode
124: data line 130: liquid crystal
140: Amphiphilic block copolymer 141: Hydrophilic unit
142: Hydrophobic unit
150: shot 160: encapsulant

Claims

1. A liquid crystal display element comprising a liquid crystal alignment layer composed of an amphiphilic block copolymer and not including an alignment film,
A TFT array substrate;
A color filter substrate; And
And a liquid crystal layer interposed between the array substrate and the color filter substrate,
Wherein the liquid crystal layer includes a liquid crystal and a liquid crystal alignment layer,
Wherein the liquid crystal alignment layer is composed of an amphiphilic block copolymer comprising at least one hydrophobic unit and at least one hydrophilic unit,
The hydrophobic unit of the amphiphilic block copolymer functions to vertically align the liquid crystal molecules by interacting with the hydrophobic liquid crystal molecules,
Wherein the hydrophilic unit of the amphiphilic block copolymer performs hydrogen bonding with the hydrophilic ITO electrode or the glass of the substrate to fix the amphiphilic block copolymer to the substrate.

The method according to claim 1,
The hydrophobic unit

or

(10 &le; m &le; 40)
The hydrophilic unit

or

(1? N? 30).

The method according to claim 1,
Wherein the hydrophilic unit is included in an amount of 10 to 70 parts by weight based on 100 parts by weight of the amphiphilic block copolymer.

The method according to claim 1,
Wherein the amphiphilic block copolymer is selected from the group consisting of polyethylene block-polyethylene glycol, polyethylene block-polypropylene glycol, polypropylene-block-polyethylene glycol, polypropylene-block-polypropylene glycol, polyethylene-block-polyethylene glycol- Characterized in that it comprises at least one member selected from the group consisting of polyethylene-block-polypropylene glycol-block-polyethylene, polyethylene glycol-block-polyethylene-block-polyethylene glycol and polypropylene glycol-block-polyethylene-block-polypropylene glycol .

A TFT array substrate;
A color filter substrate; And
And a liquid crystal layer interposed between the array substrate and the color filter substrate,
Does not include an alignment film,
Wherein the liquid crystal layer comprises a liquid crystal alignment layer composed of an amphiphilic block copolymer and a liquid crystal,
Adding an amphiphilic block copolymer comprising at least one hydrophobic unit and at least one hydrophilic unit to a liquid crystal to prepare an amphiphilic block copolymer-liquid crystal mixture;
Dropping the mixture on one side of at least one of the array substrate and the color filter substrate;
Attaching the two substrates such that the mixture is positioned between the array substrate and the color filter substrate; And
Heat treating the coagulated substrate and cooling to room temperature,
The hydrophobic unit of the amphiphilic block copolymer functions to vertically align the liquid crystal molecules by interacting with the hydrophobic liquid crystal molecules,
Wherein the hydrophilic unit of the amphiphilic block copolymer functions to fix the amphiphilic block copolymer to the substrate by hydrogen bonding with the hydrophilic ITO electrode or glass of the substrate.

The method of claim 5,
The hydrophobic unit

or

(10 &le; m &le; 40)
The hydrophilic unit

or

(1? N? 30).

The method of claim 5,
Wherein the hydrophilic unit is included in an amount of 10 to 70 parts by weight based on 100 parts by weight of the amphiphilic block copolymer.

The method of claim 5,
Wherein the amphiphilic block copolymer is added in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the liquid crystal.

The method of claim 5,
Wherein the amphiphilic block copolymer is selected from the group consisting of polyethylene block-polyethylene glycol, polyethylene block-polypropylene glycol, polypropylene-block-polyethylene glycol, polypropylene-block- polypropylene glycol, polyethylene block- Characterized in that it comprises at least one member selected from the group consisting of polyethylene-block-polypropylene glycol-block-polyethylene, polyethylene glycol-block-polyethylene-block-polyethylene glycol and polypropylene glycol-block-polyethylene-block-polypropylene glycol Of the liquid crystal display element.

The method of claim 5,
Wherein the heat treatment is performed at a temperature of 80 to 120 DEG C for 30 to 120 minutes.

As a liquid crystal alignment layer used in a liquid crystal display device not containing an alignment film,
An amphiphilic block copolymer comprising at least one hydrophobic unit and at least one hydrophilic unit,
The hydrophobic unit of the amphiphilic block copolymer functions to vertically align the liquid crystal molecules by interacting with the hydrophobic liquid crystal molecules,
Wherein the hydrophilic unit of the amphiphilic block copolymer functions to fix the amphiphilic block copolymer to the substrate by hydrogen bonding with the hydrophilic ITO electrode or glass of the substrate.

The method of claim 11,
The hydrophobic unit

or

(10 &le; m &le; 40)
The hydrophilic unit

or

(1? N? 30).

The method of claim 11,
Wherein the hydrophilic unit is contained in an amount of 10 to 70 parts by weight based on 100 parts by weight of the amphiphilic block copolymer.

The method of claim 11,
Wherein the amphiphilic block copolymer is selected from the group consisting of polyethylene block-polyethylene glycol, polyethylene block-polypropylene glycol, polypropylene-block-polyethylene glycol, polypropylene-block- polypropylene glycol, polyethylene block- Characterized in that it comprises at least one member selected from the group consisting of polyethylene-block-polypropylene glycol-block-polyethylene, polyethylene glycol-block-polyethylene-block-polyethylene glycol and polypropylene glycol-block-polyethylene-block-polypropylene glycol And a liquid crystal alignment layer.