KR100927704B1 - Liquid crystal aligning agent, Liquid crystal aligning film containing this, Liquid crystal display containing this - Google Patents

Abstract

The present invention provides a liquid crystal aligning agent comprising a first polyamic acid having a surface energy of 38 dyn / cm or more and 40 dyn / cm or less, and a second polyamic acid having a surface energy of more than 40 dyn / cm and 55 dyn / cm or less. to provide.

The liquid crystal aligning agent is excellent in chemical resistance, stable liquid crystal vertical alignment force, electro-optical characteristics, and reliability on afterimage, and is excellent in processability.

Liquid crystal alignment agent, liquid crystal alignment film, polyamic acid, polyimide, pretilt angle, electro-optical characteristics, liquid crystal alignment, liquid crystal alignment, afterimage, reliability

Description

ALIGNMENT AGENT OF LIQUID CRYSTAL, ALIGNMENT FILM OF LIQUID CRYSTAL INCLUDING THE SAME, AND LIQUID CRYSTAL DISPLAY INCLUDING THE SAME

The present invention relates to a liquid crystal aligning agent for use in a liquid crystal display device, a liquid crystal alignment film including the same, and a liquid crystal display device including the same, and more particularly, to chemical resistance, stable liquid crystal vertical alignment force, electro-optical characteristics, and afterimage The present invention relates to a liquid crystal aligning agent having excellent reliability and stable processability, a liquid crystal alignment film including the same, and a liquid crystal display device including the same.

A liquid crystal display (LCD) uses a liquid crystal alignment film. As the liquid crystal alignment film, a polymer material is mainly used. The liquid crystal alignment layer acts as a director in the arrangement of the liquid crystal molecules, so that the liquid crystal is moved by an electric field to form an image when the image is formed. In general, in order to obtain uniform brightness and high contrast ratio, it is essential to uniformly align the liquid crystal.

Conventionally, a rubbing method is used in which a polymer film such as polyimide is applied to a substrate such as glass, and the surface is rubbed in a predetermined direction with fibers such as nylon or polyester.

Generally used polyimide resin for liquid crystal aligning agent uses pyromellitic dianhydride (PMDA), non-phthalic dianhydride (BPDA) as aromatic acid dianhydride, and paraphenylenediamine (p-PDA) as aromatic diamine component. , Metaphenylenediamine (m-PDA), 4,4-methylenedianiline (MDA), 2,2-bisamino phenylhexafluoropropane (HFDA), metabisaminophenoxydiphenylsulfone (m-BAPS), Parabisaminophenoxydiphenylsulfone (p-BAPS), 4,4-bisaminophenoxyphenylpropane (BAPP), 4,4-bisaminophenoxyphenylhexafluoropropane (HF-BAPP), etc. The monomer is prepared by condensation polymerization.

However, when only aromatic acid dianhydrides and diamines are used as described above, the thermal stability, chemical resistance, mechanical properties, etc. are excellent, but transparency and solubility are degraded by charge transfer complexes, and electro-optical properties are deteriorated. There is this.

In order to solve the above problems, there is an attempt to improve the problem by introducing an aliphatic cyclic acid dianhydride monomer or aliphatic diamine (Japanese Patent Laid-Open No. 11-84391), having a side chain for increasing the pretilt angle of the liquid crystal and improving stability A functional diamine or a functional acid dianhydride having a side chain is introduced (Japanese Patent Laid-Open No. 06-136122).

In addition, the development of a vertical alignment layer that can be applied in the vertical alignment mode (VA mode) to induce the liquid crystal drive by aligning the liquid crystal vertically from the surface (US Patent No. 5,420,233). Since the vertical alignment mode has a large viewing angle and does not require an alignment process such as a rubbing process, it is easy to enlarge the size, and many panel manufacturers apply it to large display devices of 40 inches or more.

Meanwhile, with the recent growth of the liquid crystal device (LCD) market, the demand for high-quality display devices is continuously increasing, and the demand for high-performance alignment films is increasing in large liquid crystal display device manufacturers. Is growing.

Therefore, there is a continuous demand for a high-performance liquid crystal alignment film having a low defective rate in the LCD production process, excellent electro-optical characteristics, and sufficient to satisfy different requirements of liquid crystal display devices such as reliability. In most cases, the liquid crystal aligning agent usually consists of one diamine compound. A functional diamine compound having a side chain group is introduced to implement a vertical alignment in such a diamine compound. In this case, a hydrophobic side chain lowers the surface tension of the alignment layer, and is positioned in a direction perpendicular to the main chain, and has a high pretilt angle of 85 degrees or more. Expression.

However, alkyl groups having 6 to 24 carbon atoms that are used as side chains of functional diamines are flexible and have a problem in that a pretilt angle decreases when subjected to a physical impact such as liquid crystal dropping so that staining occurs on the screen. In addition, a long time use may cause an important problem such as a high level of afterimages or uneven color on the screen.

An object of the present invention is to solve the above problems, to provide a liquid crystal aligning agent excellent in chemical resistance, stable liquid crystal vertical alignment force, electro-optic properties, afterimage reliability, excellent processability.

Another object of the present invention is to provide a liquid crystal aligning film containing the liquid crystal aligning agent.

Still another object of the present invention is to provide a liquid crystal display device including the liquid crystal alignment layer.

The technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by the average person from the following description.

In order to achieve the above object, according to an embodiment of the present invention, the first polyamic acid having a surface energy of 38 dyn / cm or more and 40 dyn / cm or less, and surface energy of more than 40 dyn / cm 55 dyn / cm or less It provides a liquid crystal aligning agent comprising a second polyamic acid having a.

According to another embodiment of the present invention to provide a liquid crystal alignment film prepared by applying the liquid crystal aligning agent to a substrate.

According to still another embodiment of the present invention, a liquid crystal display including the liquid crystal alignment layer is provided.

Other specific details of embodiments of the present invention are included in the following detailed description.

The liquid crystal aligning agent of the present invention has excellent chemical resistance, stable liquid crystal vertical alignment force, electro-optical characteristics, and reliability for afterimages, and is excellent in processability, so that liquid crystal alignment is not affected by the cleaning solvent used in the cleaning process. During the liquid crystal dropping process, the vertical alignment force does not decrease even after physical impact of the dropped liquid crystal and long-term voltage application, and it is easy to remove the alignment layer during the reworking process of the upper and lower substrates caused by the printing failure during the LCD panel manufacturing process. Do.

Hereinafter, embodiments of the present invention will be described in detail. However, this is presented as an example, by which the present invention is not limited and the present invention is defined only by the scope of the claims to be described later.

According to one embodiment of the invention, the first polyamic acid having a surface energy of 38 dyn / cm or more and 40 dyn / cm or less, and the second polyamic acid having a surface energy of more than 40 dyn / cm 55 dyn / cm or less It provides the liquid crystal aligning agent containing.

The first polyamic acid and the second polyamic acid are any one acid dianhydride selected from the group consisting of aliphatic cyclic acid dianhydrides, aromatic acid dianhydrides, and combinations thereof, aromatic diamines, and functional diamines represented by the following Chemical Formula 1, And it is prepared by copolymerizing any one diamine selected from the group consisting of a combination thereof.

[Formula 1]

(In Formula 1,

R ₁₁ is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 31 carbon atoms, a substituted or unsubstituted aryl group having 1 to 30 carbon atoms, and a substituted or unsubstituted heteroaryl group having 2 to 30 carbon atoms,

R ₁₂ is a substituent selected from the group consisting of a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 1 to 30 carbon atoms, and a substituted or unsubstituted heteroaryl group having 2 to 30 carbon atoms. N ₁₂ is an integer of 0 to 3)

In the present specification, the surface energy of the first polyamic acid or the second polyamic acid is obtained by a geometric method using the contact angle of the dilute solution. As the isotropic solution, water and diiodomethane are used, and a liquid crystal aligning agent is printed on a substrate with a thickness of 800 to 1000 kPa, and then a liquid crystal aligning film formed by thermosetting at a temperature of 200 degrees or more for 10 to 15 minutes is used as a sample. . The imidation ratio of the polyimide in the formed liquid crystal aligning film is about 50 to 70%.

Substituted herein, unless specified otherwise, a hydrogen atom is a halogen group, an alkyl group of 1 to 30 carbon atoms, a haloalkyl group of 1 to 30 carbon atoms, an aryl group of 6 to 30 carbon atoms, a heteroaryl group of 2 to 30 carbon atoms, carbon atoms It means substituted with any one substituent selected from the group consisting of 1 to 20 alkoxy groups, and combinations thereof.

In addition, in the present specification, hetero means a carbon atom substituted with any one hetero atom selected from the group consisting of N, O, S, and P unless otherwise specified.

The liquid crystal aligning agent includes a predetermined amount or more of the first polyamic acid polymerized to have a suitable vertical alignment force and a low surface energy by including a certain amount or more of a functional side chain derived from a functional diamine designed to form a high vertical alignment force. Or a second polyamic acid with or without high surface energy.

The first polyamic acid has a surface energy of 38 dyn / cm or more and 40 dyn / cm or less, and the second polyamic acid has a surface energy of more than 40 dyn / cm and 55 dyn / cm or less.

The liquid crystal aligning agent prepared by blending the polyamic acid having the surface energy as described above is excellent in chemical resistance, stable liquid crystal vertical alignment force, electro-optic properties, and reliability in afterimages, and is excellent in processability. The liquid crystal alignment is not affected by the solvent, and the vertical alignment force does not decrease even after physical impact of the dropped liquid crystal and long-term voltage application during the liquid crystal dropping process, and the upper and lower substrates are processed due to printing defects during the LCD panel manufacturing process. It is easy to remove the alignment layer during the rework process.

The liquid crystal aligning agent is a liquid crystal aligning agent which solves the problems of the conventional liquid crystal aligning agent and has better characteristics in various aspects.

A conventional liquid crystal aligning agent is usually printed on a substrate and then subjected to a thermosetting process at a temperature of 200 degrees or more to produce a liquid crystal aligning film. In this case, the liquid crystal alignment layer is composed of a single layer, and in the case of a functional diamine having a long chain alkyl group, the liquid crystal alignment layer moves to the surface of the liquid crystal alignment layer and serves to cause vertical alignment.

However, the liquid crystal aligning agent according to the embodiment of the present invention includes a blend of the first polyamic acid and the second polyamic acid having different surface energies, so that the bilayer or the first polyamic may be subjected to the thermal curing process as described above. It is presumed that the acid and the second polyamic acid are formed in a complicated entangled single layer (the first polyamic acid and the second polyamic acid have the same shape as the block-type polymer on the surface).

The first polyamic acid having a low surface energy is formed near the surface of the liquid crystal alignment layer by including a relatively large amount of functional diamine, and the second polyamic acid having a high surface energy has relatively little or no functional diamine. It is formed at the middle / bottom. This may be presumed that after thermal curing the first polyamic acid and the second polyamic acid, the surface energy of the formed liquid crystal alignment layer is similar to the surface energy of the first polyamic acid having a low surface energy.

Another problem with conventional liquid crystal aligning agents is that they have low reliability for afterimages. The afterimage problem is largely due to the structure and driving principle of the panel, and it is known that the influence of the various materials constituting the panel is considerable. The cause of the afterimage problem includes an ion impurity generated from the material constituting the panel, and a charge layer accumulated on the liquid crystal layer and the liquid crystal alignment layer.

However, when using the liquid crystal aligning agent according to the embodiment of the present invention, the above problem can be effectively solved. The liquid crystal aligning film manufactured using the liquid crystal aligning agent is formed as a double layer or a single layer in which the first polyamic acid and the second polyamic acid are intricately entangled, and relatively hydrophobic, which is located near the surface of the liquid crystal aligning film. The first polyamic acid of prevents the ionic impurities and charges of the liquid crystal layer from adsorbing the liquid crystal alignment layer.

In addition, the hydrophilic second polyamic acid, which is located relatively at the middle to the bottom of the liquid crystal alignment layer, prevents impurities from rising from the lower layer of the substrate ITO, and the aromatic acid dianhydride contained in the second polyamic acid in a large amount. Due to the conjugation effect, it serves to quickly move and dissipate the charge adsorbed on the liquid crystal alignment layer.

In addition, an advantage of the liquid crystal aligning agent is that a high vertical alignment force can be obtained by the first polyamic acid. In the case of the conventional single polyamic acid, for high vertical orientation, an appropriate amount of a functional diamine having a large spacer, such as a cholesterol structure, or a certain amount of a functional diamine having a small spacer but a long chain alkyl group, must be used.

In the case of using a functional diamine having a large spacer or a long chain alkyl group as described above, there is an effect of improving the vertical alignment force, but there is a problem that decreases the content of the aromatic diamine to reduce the printability and film stability.

On the other hand, even if the liquid crystal aligning agent according to an embodiment of the present invention lowers the blend ratio of the first polyamic acid to 10 mol% based on the total content, the first polyamic acid layer having low surface energy during thermal curing is formed near the film surface. Therefore, it is possible to maintain a high vertical alignment force, there is no need to consider the problem that other properties are reduced due to the content of aromatic diamine.

As such, the blend ratio of the first polyamic acid and the second polyamic acid can be obtained without any of the above-mentioned characteristics when blending the first polyamic acid with 10 to 90 mol% and the second polyamic acid with 10 to 90 mol%. It is preferred to exhibit better properties when blending the first polyamic acid to 10 to 50 mol% and the second polyamic acid to 50 to 90 mol%. Accordingly, the liquid crystal aligning agent has a stable processability, and has high reliability for afterimages while maintaining excellent chemical resistance and vertical alignment force.

The functional diamine represented by Chemical Formula 1 induces liquid crystal alignment in the side chain direction. Thereby, processability and chemical resistance are improved, and stability can be obtained with respect to a printing process, a rubbing process, and a washing process.

In addition, the liquid crystal orientation induced in the side chain direction facilitates the adjustment of the pretilt angle due to the change in the content of the functional diamine. This property is also suitable for the vertical alignment mode for orienting the liquid crystal in the vertical direction, and has a good influence on the stability of the vertical alignment force.

In addition, since the pretilt angle is adjusted according to the content of the functional diamine, it is also possible to prepare a polyamic acid using only functional diamine and use it as a liquid crystal alignment layer without any aromatic diamine depending on the mode of the liquid crystal display. That is, the use of aromatic diamines is optional.

In view of the above, the first polyamic acid is 5 to 100 mol%, preferably 10 to 70 mol%, more preferably 20 to 60% of the functional diamine represented by Chemical Formula 1 with respect to the entire diamine. Contains in mol%. In addition, the second polyamic acid preferably contains 0 to 20 mol% of the functional diamine represented by Chemical Formula 1 with respect to the entire diamine.

The first polyamic acid or the second polyamic acid is any one acid dianhydride selected from the group consisting of aliphatic cyclic dianhydrides, aromatic dianhydrides, and combinations thereof, aromatic diamines, functional diamines represented by the following Formula 1, and It can be produced by copolymerizing any one diamine selected from the group consisting of a combination of these. The method of preparing the polyamic acid by copolymerizing the acid dianhydride and the diamine may be applied without being limited to a method known to be possible to copolymerize the conventional polyamic acid.

Examples of the aromatic cyclic diamines used in the preparation of the first polyamic acid or the second polyamic acid include paraphenylenediamine (p-PDA), 4,4-methylenedianiline (MDA), and 4,4-oxydianiline ( ODA), metabisaminophenoxydiphenylsulfone (m-BAPS), parabisaminophenoxydiphenylsulfone (p-BAPS), 2,2-bisaminophenoxyphenylpropane (BAPP), 2,2-bisaminophenoxy Ciphenylhexafluoropropane (HF-BAPP), 1,4-diamino-2-methoxybenzene and the like may be preferably used, but is not limited thereto. The amount of the aromatic diamine used is preferably 0 to 99.9 mol%, preferably 30 to 99.5 mol%, more preferably 40 to 90 mol%, based on the total diamine content.

The aromatic acid dianhydride used in the production of the first polyamic acid or the second polyamic acid enables the liquid crystal alignment film coated with a thickness of 800 to 1000 kPa to withstand the rubbing process, and to maintain heat resistance to a high temperature processing process of 200 ° C. or higher. It has good chemical resistance.

The aromatic acid dianhydrides include pyromellitic dianhydrides (PMDA), nonphthalic dianhydrides (BPDA), oxydiphthalic dianhydrides (ODPA), benzophenone tetracarboxylic dianhydrides (BTDA), and hexafluoroisopropylidene diphthalic acid. Anhydride (6-FDA) and the like can be preferably used, but is not limited thereto.

The content of the aromatic acid dianhydride is 10 to 95 mol%, more preferably 50 to 80 mol% based on the total acid dianhydride used. When the content of the aromatic acid dianhydride is less than 10 mol%, mechanical properties and heat resistance of the liquid crystal alignment layer are lowered, and when it exceeds 80 mol%, electrical properties such as voltage retention are lowered, which is not preferable.

The aliphatic cyclic acid dianhydride used for preparing the first polyamic acid or the second polyamic acid is insoluble in a general organic solvent, low transmittance in the visible light region due to a charge transfer complex, and molecular structurally high polarity. Compensate for problems such as deterioration of electro-optic properties.

As the aliphatic cyclic acid dianhydride, 5- (2,5-dioxotetrahydrofuryl) -3-methylcyclohexene-1,2-dicarboxylic acid anhydride (DOCDA), bicyclooctene-2,3,5 , 6-tetracarboxylic dianhydride (BODA), 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), 1,2,3,4-cyclopentanetetracarboxylic dianhydride (CPDA), 1,2,4,5-cyclohexanetetracarboxylic dianhydride (CHDA) may be preferably used, but is not limited thereto. The content of the aliphatic cyclic acid dianhydride is 5 to 90 mol%, preferably 10 to 65 mol% based on the total acid dianhydride used.

Preferably, the first polyamic acid and the second polyamic acid have a number average molecular weight of 10,000 to 500,000 g / mol, and when the imidation is performed, the glass transition temperature has a range of 200 to 350 ° C. When the number average molecular weight of the first polyamic acid or the second polyamic acid is less than 10,000 g / mol, thermal stability, chemical resistance, and the like as the alignment layer are reduced, which is not preferable. When the number average molecular weight of the first polyamic acid or the second polyamic acid exceeds 500,000 g / mol, the viscosity may be too high to form a uniform film due to poor printability.

According to another embodiment of the present invention to provide a liquid crystal alignment film prepared using the liquid crystal aligning agent.

The liquid crystal alignment film may be prepared by applying a liquid crystal alignment film-forming composition prepared by adding the liquid crystal aligning agent to a solvent, onto a substrate.

The solvent includes N-methyl-2-pyrrolidone, N, N-dimethyl acetamide, N, N-dimethyl formamide, dimethyl sulfoxide, γ-butyrolactone, and meta cresol, phenol, halogenated phenol, and the like. A tall solvent etc. can be used preferably.

The solvent may further include an alcohol, ketone, ester, ether, hydrocarbon, or halogenated hydrocarbon, which is a poor solvent, in an appropriate ratio as long as the soluble polyimide polymer is not precipitated. This is because the poor solvents lower the surface energy of the liquid crystal aligning agent to improve the spreadability and flatness during application.

The poor solvent is preferably used in the range of 1 to 90% by volume with respect to the total solvent, more preferably in the range of 1 to 70% by volume.

Specific examples of the poor solvent include methanol, ethanol, isopropanol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, acetate Butyl, diethyl oxalate, malonic ester, diethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol phenyl ether, ethylene glycol phenyl methyl ether, ethylene glycol phenyl ethyl ether, ethylene glycol dimethylethyl, diethylene Glycol Dimethylethyl, Diethylene Glycol Ether, Diethylene Glycol Monomethyl Ether, Diethelin Glycol Monoethyl Ether, Diethylene Glycol Monomethyl Ether Acetate, Diethylene Glycol Monoethyl Ether Acetate, Ethylene Glycol Methyl Ether Acetate, Ethylene Glycol Ethyl Ether acete , 4-hydroxy-4-methyl-2-pentanone, 2-hydroxy ethyl propionate, 2-hydroxy-2-methyl ethyl propionate, ethoxy acetate, ethyl hydroxy acetate, 2-hydroxy-3 -Methyl methyl butyrate, methyl 3-methoxy propionate, ethyl 3-methoxy propionate, ethyl 3-ethoxy propionate, methyl 3-ethoxy propionate, methyl methoxy butanol, ethyl methoxy butanol, methyl ethoxy butanol, ethyl Ethoxy butanol, tetrahydrofuran, dichloromethane, 1,2-dichloroethane, 1,4-dichloro butane, trichloroethane, chlorobenzene, o-dichlorobenzene, hexane, heptane, octane, benzene, toluene, xylene, and The thing chosen from the group which consists of these combinations is mentioned.

The first polyamic acid or the second polyamic acid is N-methyl-2-pyrrolidone (NMP), gamma-butyrolactone (GBL), dimethylformamide (DMF), dimethylacetamide (DMAc), tetrahydro Better solubility in aprotic polar solvents such as furan (THF) and the like. The excellent solubility of the first polyamic acid or the second polyamic acid has a great effect of the functional diamine in which three benzene rings are three-dimensionally present with three-dimensional repulsive force in terms of introduction of aliphatic cyclic acid dianhydride and molecular structure. It is considered to be. In recent years, the liquid crystal aligning agent can be more preferably used in the situation where the printability of the liquid crystal aligning agent is very important due to the enlargement, high resolution and high quality of the liquid crystal display element.

The content of the solvent in the composition for forming the liquid crystal alignment layer is not particularly determined, but the solid content of the liquid crystal alignment agent is 1 to 30% by weight, preferably 2 to 15% by weight, more preferably 4 to 10% by weight. use. When the content of the solid content is less than 1% by weight, there may be a problem that the uniformity of the film is lowered under the influence of the substrate surface during printing, and when the content of the solid content exceeds 30% by weight, the uniformity of the film formed during printing is reduced by the high viscosity. May be lowered and transmittance may be lowered.

The composition for forming a liquid crystal alignment layer may include at least one epoxy compound having 2 to 4 epoxy functional groups in order to improve reliability and electro-optic properties. It is preferable that the said epoxy compound is contained in 0.01-50 weight part with respect to 100 weight part of said liquid crystal aligning agents, It is more preferable that it is contained in 1-30 weight part. When the content of the epoxy compound exceeds 50 parts by weight may reduce the printability or flatness when applied to the substrate, when less than 0.01 parts by weight, the effect of adding the epoxy compound is insignificant.

Specific examples of the epoxy compound include N, N, N ', N'-tetraglycidyl-4,4'-diaminodiphenylmethane (TGDDM), N, N, N', N'-tetraglycidyl -4,4'-diaminodiphenylethane, N, N, N ', N'-tetraglycidyl-4,4'-diaminodiphenylpropane, N, N, N', N'-tetragly Cydyl-4,4'-diaminodiphenylbutane, N, N, N ', N'-tetraglycidyl-4,4'-diaminobenzene, and the like, but are not limited thereto.

In addition, the composition for forming a liquid crystal alignment layer may further use a silane coupling agent or a surfactant to improve adhesion to the substrate and to improve flatness and film coating properties.

The said liquid crystal aligning film formation composition can be apply | coated to a board | substrate, and a liquid crystal aligning film can be formed. As a method of apply | coating the said liquid crystal aligning film formation composition to the said board | substrate, a spin coat method, the flexographic printing method, the inkjet method, etc. are mentioned. Especially, the flexographic printing method can be used suitably because it is excellent in the uniformity of the formed coating film and easy to enlarge.

The substrate can be used without particular limitation as long as it is a substrate having high transparency, and a plastic substrate such as a glass substrate or an acrylic substrate or a polycarbonate substrate can be used. Moreover, it is preferable to use the board | substrate with which the ITO electrode etc. for liquid crystal drive were formed from a viewpoint of the simplification of a manufacturing process.

The composition for forming a liquid crystal alignment film is uniformly coated on a substrate in order to increase the uniformity of the coating film, and then, for 1 to 100 minutes at room temperature to 200 ° C, preferably 30 to 150 ° C, more preferably 40 to 120 ° C. It is preferable to perform drying. By adjusting the volatilization degree of each component of the composition for liquid crystal aligning film formation through the said temporary drying, the coating film which is uniform and there is no deviation can be obtained.

Thereafter, the liquid crystal aligning film can be formed by baking for 5 to 300 minutes at a temperature of 80 to 300 ° C, preferably 120 to 280 ° C to completely evaporate the solvent.

According to another embodiment of the present invention, a display device including the liquid crystal alignment layer is provided. It is preferable that the said display device is a liquid crystal display device.

1 is a cross-sectional view of a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the liquid crystal display 1 according to the exemplary embodiment of the present invention includes a lower panel 100, an upper panel 200, and a liquid crystal layer 3.

The lower panel 100 includes a gate conductor including a plurality of gate lines (not shown) and a plurality of storage electrodes 133 on an upper surface of the first substrate 110. . On the gate conductor, a gate insulating layer 140, a plurality of semiconductors 154, a plurality of pairs of ohmic contacts 163 and 165, a plurality of source electrodes 173, And a plurality of drain electrodes 175 are formed in this order.

One gate electrode 124, one source electrode 173, and one drain electrode 175 together with the semiconductor 154 form one thin film transistor (TFT).

A passivation layer 180 is formed on the exposed portion of the semiconductor 154, the source electrode 173, the drain electrode 175, and the gate insulating layer 140. A plurality of pixel electrodes 191 are formed on the passivation layer 180.

Next, the upper panel 200 will be described.

In the upper panel 200, a light blocking member 220 is formed on the second substrate 210. A plurality of color filters 230 are formed on the second substrate 210 and the light blocking member 220, and an overcoat 250 is formed on the color filters 230. The overcoat 250 may prevent the color filter 230 from being exposed to the liquid crystal layer 3, and the overcoat 250 may be omitted.

The first liquid crystal alignment layer 12 and the second liquid crystal alignment layer 22 are formed on the pixel electrode 191 of the lower panel 100 and the common electrode 270 of the upper panel 200, respectively. The first liquid crystal alignment layer 12 and the second liquid crystal alignment layer 22 are manufactured by using the liquid crystal alignment agent according to the embodiment of the present invention.

In FIG. 1, the liquid crystal alignment layers 12 and 22 are formed on both the lower panel 100 and the upper panel 200. However, the liquid crystal alignment layers 12 and 22 may be the upper panel 200 or the lower panel. It may be formed only in any one of the (100).

The following presents specific embodiments of the present invention. However, the embodiments described below are merely for illustrating or explaining the present invention in detail, and thus the present invention is not limited thereto.

(Manufacture of liquid crystal aligning agent)

( Production Example  One)

0.80 mol of 4,4-oxydianiline and 1- (3,5 diaminophenyl) -3-octadecyl-succine, while passing nitrogen through a four-necked flask equipped with a stirrer, a thermostat, a nitrogen gas injector and a cooler 0.20 mol of imide was added, and N-methyl-2-pyrrolidone (NMP) was added to dissolve it. Here, 0.50 mol of 5- (2,5-dioxotetrahydrofuryl) -3-methylcyclohexane-1,2-dicarboxylic acid anhydride (DOCDA) in solid state and 0.50 mol of pyromellitic dianhydride (PMDA) Was added and stirred vigorously. At this time, the solid content was 15% by weight in mass ratio, and the reaction was carried out for 4 hours while maintaining the temperature below 25 ° C. to obtain the first polyamic acid solution (A-1) (surface energy: 38.5 ± 0.5 dyn / cm). Prepared.

( Production Example  2)

1.00 mol of 4,4-methylenedianiline and 0.50 mol of 5- (2,5-dioxotetrahydrofuryl) -3-methylcyclohexane-1,2-dicarboxylic acid anhydride (DOCDA) in solid state and pyromelli A second polyamic acid solution (A-2) (surface energy: 51.5 ± 0.5 dyn / cm) was prepared in the same manner as in Preparation Example 1, except that 0.50 mol of dianhydride (PMDA) was used.

( Production Example  3)

0.40 mol of 4,4-oxydianiline and 0.60 mol of 1- (3,5 diaminophenyl) -3-octadecyl-succinimide, 5- (2,5-dioxotetrahydrofuryl) -3-methylcyclo Except that 0.50 mol of hexane-1,2-dicarboxylic acid anhydride (DOCDA) and 0.50 mol of pyromellitic dianhydride (PMDA) were used in the same manner as in Preparation Example 1, the first polyamic acid solution (B -1) (surface energy: 39.0 ± 0.5 dyn / cm) was obtained.

( Production Example  4)

0.80 mol of 4,4-oxydianiline and 0.20 mol of 1- (3,5 diaminophenyl) -3-octadecyl-succinimide, 5- (2,5-dioxotetrahydrofuryl) -3 in the solid state A first polyamic acid solution was prepared in the same manner as in Preparation Example 1, except that 0.50 mol of methylcyclohexane-1,2-dicarboxylic acid anhydride (DOCDA) and 0.50 mol of pyromellitic dianhydride (PMDA) were used. C-1) (surface energy: 38.5 ± 0.5 dyn / cm) was prepared.

( Production Example  5)

0.85 mol of 4,4-methylenedianiline and 0.15 mol of 1- (3,5 diaminophenyl) -3-octadecyl-succinimide, 5- (2,5-dioxotetrahydrofuryl) -3 in the solid state A second polyamic acid solution was prepared in the same manner as in Preparation Example 1, except that 0.50 mol of methylcyclohexane-1,2-dicarboxylic acid anhydride (DOCDA) and 0.50 mol of pyromellitic dianhydride (PMDA) were used. B-2) (surface energy: 41.5 ± 0.5 dyn / cm) was prepared.

( Production Example  6)

0.40 mol of 4,4-oxydianiline and 0.60 mol of 1- (3,5 diaminophenyl) -3-octadecyl-succinimide, 5- (2,5-dioxotetrahydrofuryl) -3-methylcyclo Except that 0.50 mol of hexane-1,2-dicarboxylic acid anhydride (DOCDA) and 0.50 mol of pyromellitic dianhydride (PMDA) were used in the same manner as in Example 1 above, the first polyamic acid solution (D -1) (surface energy: 39.5 ± 0.5 dyn / cm) was obtained.

( Production Example  7)

Example 4,4-oxydianiline except that 0.08 mol, 4,4-methylenedianiline 0.90 mol, and 0.02 mol of 1- (3,5 diaminophenyl) -3-octadecyl-succinimide 1, the second polyamic acid solution (C-2) (surface energy: 49.5 ± 0.5 dyn / cm) was prepared.

( Production Example  8)

Example 4,4-oxydianiline except that 0.20 mol, 4,4-methylenedianiline 0.50 mol, 1- (3,5 diaminophenyl) -3-octadecyl-succinimide were used The same procedure as in 1 was carried out to prepare a first polyamic acid solution (E-1) (surface energy: 38.5 ± 0.5 dyn / cm).

( Example  1 to 8, Comparative example  1, and Comparative example  2)

As shown in Table 1, a first polyamic acid solution and a second polyamic acid solution were mixed to prepare a liquid crystal aligning agent.

TABLE 1

First polyamic acid Second polyamic acid Mixing ratio (mol%) (first polyamic acid: second polyamic acid) Example 1 A-1 A-2 10:90 Example 2 A-1 A-2 50:50 Example 3 B-1 A-2 10:90 Example 4 B-1 A-2 50:50 Example 5 C-1 B-2 10:90 Example 6 C-1 B-2 50:50 Example 7 D-1 B-2 10:90 Example 8 D-1 B-2 50:50 Comparative Example 1 - C-2 Second polyamic acid alone Comparative Example 2 E-1 - First polyamic acid alone

(Printability Evaluation)

The liquid crystal aligning agents prepared in Examples 1 to 8, Comparative Example 1, and Comparative Example 2 were applied onto the ITO surface of 10 cm × 10 cm sized ITO glass, spin-coated to make a thickness of 800 to 1000 mm 3, and then hot The sample was sampled through a desolvent process at 80 ° C. and a curing process at 210 ° C. for 15 minutes on a hot plate. The printability of the liquid crystal aligning agent was evaluated by observing the spreading property and the curling property of the prepared sample through visual observation and an optical microscope. The printability evaluation results are shown in Table 2 below.

(Perpendicular Orientation , Chemical resistance, and Pretilt  evaluation)

In order to evaluate the vertical orientation, chemical resistance, and pretilt angle of the liquid crystal aligning agent, a liquid crystal test cell different from the above sample was produced and used. The manufacture of the liquid crystal cell is as follows. The ITO glass substrate was patterned using a photolithography process to remove other portions of ITO, leaving only 1.5 cm × 1.5 cm square ITO shapes and electrode ITO shapes for voltage application.

The liquid crystal aligning agent was applied to the patterned ITO surface substrate and spin-coated to make a thickness of 800 to 1000 Å, followed by a curing process at 80 ° C. and 210 ° C. for 15 minutes. The two substrates thus prepared were bonded to each other in a square ITO shape up and down while maintaining a uniform cell gap using a spacer of 4.75 μm and a thermosetting sealant. After filling the liquid crystal in the cell made in this way, the perpendicular alignment of the liquid crystal was observed using an orthogonally polarized optical microscope, and the results are summarized in Table 2 below.

In addition, a cleaning step was added to evaluate chemical resistance and resistance to cleaning of the liquid crystal aligning agent produced by the above method. The surface of the alignment layer on the thermoset substrate was sufficiently cleaned with isopropyl alcohol and pure water, and then the cleaning solution was removed with an air knife at a pressure of 1.0 to 2.0 kgf / cm ^2. The liquid crystal cell was fabricated by bonding to an anti-parallel), and the liquid crystal alignment was disturbed by the cleaning solvent, that is, the formation of spots while driving by applying an AC voltage of 60 Hz and 2.0 to 3.0 V to the cell thus manufactured. Observation is shown in Table 2 below.

In addition, the crystal rotation method was used to measure the pretilt angle of the liquid crystal by the liquid crystal aligning agent. In order to compare the measured values of the pretilt angle, a rubbing process was applied to fabricate the liquid crystal test cell to compare the fine vertical alignment forces, and the measurement results are shown in Table 2 below.

TABLE 2

Printability Liquid crystal alignment Cleaning stains Pretilt angle (°) Example 1 Good ○ ○ 84.0 ± 1.0 Example 2 Good ○ ◎ 85.0 ± 1.0 Example 3 Good ○ ◎ 88.0 ± 1.0 Example 4 Good ○ ◎ ＞ 89.5 Example 5 Good ◎ ◎ 89.0 ± 0.5 Example 6 Good ◎ ◎ 89.0 ± 0.5 Example 7 Good ◎ ◎ 89.0 ± 0.5 Example 8 Good ◎ ◎ ＞ 89.5 Comparative Example 1 Good X X - Comparative Example 2 Good △ △ <80.0

In the said Table 2, the case where it was excellent in liquid crystal orientation was shown by (circle), the case where it was favorable was shown by (circle), the case where it was not favorable was shown by (triangle | delta), and the case where it was a defect was shown by X. In addition, in the above Table 2, the case where cleaning staining did not occur at all was indicated by?, The case where almost no occurrence was indicated by ○, the case where a large number of occurrences were indicated by △, and the case where the defect was indicated by X.

Referring to Table 2, it can be seen that the liquid crystal aligning agent prepared in Examples 1 to 8 is excellent in printability, liquid crystal alignment, and pretilt angle, and the liquid crystal alignment is not affected by the cleaning solvent.

On the other hand, the liquid crystal aligning agent prepared in Comparative Example 1 and Comparative Example 2, both the liquid crystal alignment, and the pretilt angle is not good, it can be seen that a lot of stains are generated by the cleaning solvent.

The present invention is not limited to the above embodiments, but may be manufactured in various forms, and a person skilled in the art to which the present invention pertains has another specific form without changing the technical spirit or essential features of the present invention. It will be appreciated that the present invention may be practiced as. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

1 is a cross-sectional view of a liquid crystal display according to an exemplary embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

1: liquid crystal display device 3: liquid crystal layer

12: first liquid crystal alignment film 22: second liquid crystal alignment film

100: lower display panel 110: first substrate

175: drain electrode 191: pixel electrode

200: upper display panel 210: second substrate

230: color filter 270: common electrode

Claims (10)

A liquid crystal aligning agent comprising a first polyamic acid having a surface energy of 38 dyn / cm or more and 40 dyn / cm or less, and a second polyamic acid having a surface energy of more than 40 dyn / cm and 55 dyn / cm or less. The method of claim 1, The first polyamic acid and the second polyamic acid Any one acid dianhydride selected from the group consisting of aliphatic cyclic acid dianhydrides, aromatic acid dianhydrides, and combinations thereof; Aromatic diamine, functional diamine represented by the following formula (1), and any one diamine selected from the group consisting of a combination thereof Liquid crystal aligning agent which is manufactured by copolymerizing. [Formula 1]

(In Formula 1, R ₁₁ is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 1 to 30 carbon atoms, and a substituted or unsubstituted heteroaryl group having 2 to 30 carbon atoms, R ₁₂ is a substituent selected from the group consisting of a substituted or unsubstituted alkyl group having 1 to 31 carbon atoms, a substituted or unsubstituted aryl group having 1 to 30 carbon atoms, and a substituted or unsubstituted heteroaryl group having 2 to 30 carbon atoms. N ₁₂ is an integer of 0 to 3, The substituted Iran hydrogen atom is a halogen group, an alkyl group having 1 to 30 carbon atoms, a haloalkyl group having 1 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, a heteroaryl group having 2 to 30 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and Means substituted with any one of substituents selected from the group consisting of a combination of these) The method of claim 2, The first polyamic acid is a liquid crystal aligning agent comprising a functional diamine represented by the formula (1) in 5 to 100 mol% with respect to the entire diamine. The method of claim 2, The second polyamic acid is a liquid crystal aligning agent comprising a functional diamine represented by the formula (1) in an amount of 0 to 20 mol% based on the entire diamine. The method of claim 1, Wherein the first polyamic acid or the second polyamic acid comprises 10 to 95 mol% of aromatic acid dianhydrides and 5 to 90 mol% of aliphatic cyclic acid dianhydrides in the total acid dianhydrides. The method of claim 1, And the liquid crystal aligning agent comprises 10 to 90 mol% of the first polyamic acid and 10 to 90 mol% of the second polyamic acid. The method of claim 1, Wherein the blend of the first polyamic acid and the second polyamic acid has a number average molecular weight of 10,000 to 500,000 g / mol. The liquid crystal aligning film manufactured by apply | coating the liquid crystal aligning agent as described in any one of Claims 1-7 to a board | substrate. The method of claim 8, The liquid crystal alignment layer may be a double layer including a layer including the first polyamic acid and a layer including the second polyamic acid. A single layer comprising a block type polymer of the first polyamic acid and the second polyamic acid It is a liquid crystal aligning film. A liquid crystal display device comprising the liquid crystal alignment film according to claim 8.

Images