KR101610559B1 - Liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal display element - Google Patents

Abstract

Reaction of a tetracarboxylic acid dianhydride component containing a tetracarboxylic acid dianhydride having an alicyclic structure or an aliphatic structure with a diamine component containing a diamine having a urea structure and a diamine having a secondary amine at a polymerization reaction site ≪ / RTI > wherein the liquid crystal aligning agent comprises polyamic acid.

Description

TECHNICAL FIELD [0001] The present invention relates to a liquid crystal alignment film, a liquid crystal alignment film, a liquid crystal alignment film,

The present invention relates to a liquid crystal aligning agent, a liquid crystal alignment film and a liquid crystal display element.

BACKGROUND ART A liquid crystal display element is widely used as a display device at present. A liquid crystal alignment film which is a constituent member of a liquid crystal display element is a film that uniformly arranges liquid crystals. However, when the liquid crystal alignment property is insufficient, display defects such as display unevenness and after-image are liable to occur. The occurrence of defective display may involve ionic impurities in the liquid crystal, and the same proposal as in Patent Document 1 has been made as a method for reducing the impurities.

Further, in the liquid crystal alignment film, it is general to carry out an alignment treatment called rubbing in which the surface of the polymer film is rubbed with a cloth. However, if the rubbing resistance of the liquid crystal alignment film is insufficient, the film may be scratched to cause damage or dust, the film itself may peel off, or the display quality of the liquid crystal display element may deteriorate. Therefore, the liquid crystal alignment film is required to have high rubbing resistance, and a method as shown in Patent Documents 2 to 5 has been proposed.

Further, it is known that when the volume resistivity of the liquid crystal alignment film is high, the accumulated charge is hardly relaxed, and it takes time until the afterimage is erased. As a method for shortening the afterglow erase time, a method using a liquid crystal alignment film having a low volume resistivity as in Patent Document 6 has been proposed.

Japanese Patent Application Laid-Open No. 2002-323701 Japanese Patent Application Laid-Open No. 7-120769 Japanese Patent Application Laid-Open No. 9-146100 Japanese Patent Application Laid-Open No. 2008-90297 Japanese Patent Application Laid-Open No. 9-258229 International Publication No. 2004/053583

In the FFS (Fringe Field Switching) mode recently developed as one mode of the liquid crystal display element, when a liquid crystal alignment film having a low volume resistivity is used, the time until the accumulated charge is relaxed is short, . It was confirmed that in the case of an FFS mode liquid crystal display element in which charges are liable to be accumulated, afterimage easily occurs even by driving for a short time.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and to provide a liquid crystal alignment film which satisfies various properties required for a liquid crystal display device. That is, an object of the present invention is to provide a liquid crystal alignment film having good liquid crystal alignment and rubbing resistance, having a small ion density, and a small accumulated charge in an FFS mode liquid crystal display element.

It is also an object of the present invention to provide a liquid crystal aligning agent capable of obtaining the liquid crystal alignment film.

It is also an object of the present invention to provide a liquid crystal display element having excellent display quality.

As a result of intensive studies, the present inventors have found that a tetracarboxylic acid dianhydride having an alicyclic structure or an aliphatic structure, a diamine having a urea structure, and a diamine having a secondary amine at the polymerization reaction site It has been found that the above objects can be achieved by a liquid crystal aligning agent containing a polyamic acid obtained by using a diamine.

Thus, the present invention has the following points.

1. A process for producing a tetracarboxylic acid dianhydride having a tetracarboxylic acid dianhydride having an alicyclic structure or an aliphatic structure, a diamine component containing a diamine having a urea structure and a diamine having a secondary amine at a polymerization reaction site, ≪ / RTI > wherein the liquid crystal aligning agent comprises a polyamic acid.

2. The liquid crystal aligning agent according to 1, wherein the tetracarboxylic acid dianhydride component contains a tetracarboxylic dianhydride having an alicyclic structure or an aliphatic structure in an amount of 50 mol% or more.

3. The liquid crystal aligning agent according to 1 or 2, wherein the diamine component contains 10 to 70 mol% of a diamine having a secondary amine at the polymerization reaction site.

4. The liquid crystal aligning agent according to any one of items 1 to 3, wherein the diamine component contains 10 to 70 mol% of a diamine having a urea structure.

5. The liquid crystal aligning agent according to any one of items 1 to 4, wherein the diamine having a secondary amine at the polymerization reaction site is a diamine represented by the following formula (1).

[Chemical Formula 1]

(In the formula (1), X represents an aromatic ring, R ¹ represents an alkylene group having 1 to 5 carbon atoms, R ² Represents an alkyl group having 1 to 4 carbon atoms.)

6. The liquid crystal aligning agent according to any one of items 1 to 5, wherein the diamine having a urea structure is a diamine represented by the following formula (2).

(2)

(In the formula (2), Y represents an oxygen atom or a sulfur atom, and R ³ , R ⁴ Each independently represent an alkylene group having 1 to 3 carbon atoms, Z ¹ and Z ² Each independently represents a single bond, -O-, -S-, -OCO-, or -COO-.)

7. A liquid crystal alignment film obtained by using the liquid crystal aligning agent according to any one of claims 1 to 6.

8. A liquid crystal display element comprising a liquid crystal alignment film.

According to the present invention, it is possible to provide a FFS mode liquid crystal display device which has a high orientation control function for liquid crystals, that is, excellent liquid crystal alignability, high rub resistance, low ion density when used as a liquid crystal display device, A liquid crystal aligning film obtained by using the liquid crystal aligning agent, and a liquid crystal display device comprising the liquid crystal aligning film.

The liquid crystal aligning agent of the present invention contains a polyamic acid obtained by reacting a diamine component and a tetracarboxylic acid dianhydride component. In the present invention, the tetracarboxylic acid dianhydride component as the raw material of the polyamic acid contains a tetracarboxylic acid dianhydride having an alicyclic structure or an aliphatic structure, and the diamine component as a raw material of the polyamic acid is a urea structure And a diamine having a secondary amine at the polymerization site. The tetracarboxylic acid dianhydride contained in the tetracarboxylic acid dianhydride component and the diamine contained in the diamine component may be one or more species.

Hereinafter, the diamine contained in the diamine component and the tetracarboxylic acid dianhydride contained in the tetracarboxylic acid dianhydride component will be described in detail.

≪ Diamine having a secondary amine at the polymerization reaction site >

Specific examples of the diamine having a secondary amine at the polymerization reaction site contained as an essential component in the diamine component as the raw material of the polyamic acid contained in the liquid crystal aligning agent of the present invention include diamines represented by the following formula (1) . Of course, the diamine component may contain, in place of the diamine represented by the formula (1), or a diamine represented by the formula (1) and a diamine having a secondary amine at the polymerization reaction site other than the diamine represented by the formula (1) . The polymerization reaction site is a site that reacts with the tetracarboxylic acid dianhydride component, and the diamine secondary amine having a secondary amine at the polymerization reaction site, i.e., -NH- is reacted with the tetracarboxylic acid dianhydride component do.

(3)

In the formula (1), X represents an aromatic ring, R ¹ represents an alkylene group having 1 to 5 carbon atoms, R ² Represents an alkyl group having 1 to 4 carbon atoms.

X in the formula is a moiety for allowing the aromatic amine moiety to be present in the diamine having a secondary amine at the polymerization reaction site, so that the aromatic ring moiety is not particularly limited as long as it is an aromatic ring. X is preferably phenylene or naphthalene, and phenylene is particularly preferable in view of versatility from the viewpoints of availability of raw materials, easiness of synthesis, liquid crystal orientation and the like. When X is phenylene, that is, when H ₂ NX is aminobenzene, the substitution position of R ¹ is preferably a meta position or a para position.

R ¹ represents an alkylene group having 1 to 5 carbon atoms. From the viewpoint of imparting solubility of the polymer (polyamic acid), R ¹ may be branched or have a cyclic structure when it is in the range of the number of carbon atoms, but from the viewpoint of liquid crystal alignability and rubbing resistance, a linear structure is preferable, Particularly preferred is an alkylene group having 1 or 2 carbon atoms.

R ² Represents an alkyl group having 1 to 4 carbon atoms, and may have a linear chain or branched structure. On the other hand, from the viewpoint of the liquid crystal alignability and the reactivity of the diamine, it is preferably a group as small as possible, and a methyl group and an ethyl group are particularly preferable.

Preferable examples of the diamine represented by the formula (1) are shown below, but are not limited thereto.

[Chemical Formula 4]

The content of the diamine having a secondary amine in the polymerization reaction site such as the diamine represented by the formula (1) is preferably 10 to 70 mol% of the total diamine component. However, from the viewpoint of the high rubbing resistance and the low accumulated charge amount, To 65 mol%, and particularly preferably from 20 to 60 mol%.

≪ Diamine having urea structure >

Specific examples of the diamine having a urea structure contained as an essential component in the diamine component which is a raw material of the polyamic acid contained in the liquid crystal aligning agent of the present invention include diamines represented by the following formula (2). Of course, the diamine component may contain a diamine having a urea structure other than the diamine represented by the formula (2) in place of the diamine represented by the formula (2) or the diamine represented by the formula (2).

[Chemical Formula 5]

In the formula (2), Y represents an oxygen atom or a sulfur atom, and R ³ , R ⁴ Each independently represent an alkylene group having 1 to 3 carbon atoms, Z ¹ and Z ² Each independently represents a single bond, -O-, -S-, -OCO-, or -COO-.

In the formula (2), when Y is an oxygen atom, it is urea, and when it is a sulfur atom, thiourea (hereinafter, urea and thiourea groups may be collectively referred to as (thio) urea) . The urea group or thiourea group is a urea structure.

Here, both the oxygen atom and the sulfur atom are atoms having a high electronegativity. On the nitrogen atom, two hydrogen atoms having high donor properties exist. Therefore, the oxygen or sulfur atom of (thio) urea binds relatively strongly by non-covalent bonding with two hydrogen atoms of another (thio) urea. In the present invention, the urea structure of the diamine having a urea structure is preferably a urea group, and Y in the formula (2) is preferably an oxygen atom. This is because, when the oxygen atom and the sulfur atom are compared, the electronegativity is high because the oxygen atom is high, so that the urea structure is more likely to self-aggregate than the thiourea structure. The liquid crystal aligning agent of the present invention has a (thio) urea group derived from a diamine having a urea structure such as a diamine represented by the formula (2) in a polymer chain (polyamic acid chain). Therefore, rubbing resistance can be improved by electrostatic interaction (non-covalent bond) between (thio) urea babies. In this respect, the present invention is different from the method of improving the rubbing resistance by connecting the chains of the polymer chains generally used in the field of the liquid crystal alignment film with a cross-linking agent.

In the formula (2), R ³ and R ⁴ Each independently represent an alkylene group having 1 to 3 carbon atoms, and the structure thereof may be either linear or branched. Specific examples thereof include a methylene group, an ethylene group, a trimethylene group, a 1-methylethylene group, and a 2-methylethylene group. Of these, a structure having a free-rotation site as possible and a small steric hindrance as possible is preferable from the viewpoints of liquid crystal aligning property and rubbing resistance, and specifically, a methylene group, an ethylene group and a trimethylene group are preferable.

In formula (2), Z ¹ and Z ² Are each independently a single bond, -O-, -S-, -OCO-, or -COO-. Z ¹ and Z ² are preferably as flexible as possible and have a small steric hindrance from the viewpoint of liquid crystal alignability and rubbing resistance, and are preferably a single bond, -O-, or -S-.

The structure between the (thio) urea group and the benzene ring is preferably symmetrical with respect to the (thio) urea group in the sense that a film with a high film density is formed and a stronger liquid crystal alignment film is formed, and -R ³ -Z ¹ - and -R ⁴ -Z ² - have the same structure. Among the diamines represented by the formula (2), those represented by the following formulas (2-a) to (2-c) are preferable. In the formula (2-a), R < ¹¹ > and R < ²¹ > are each an alkylene group of 1 to 3 carbon atoms having the same carbon number. In the formula (2-b), R ¹² and R ²² Is an alkylene group having 1 to 3 carbon atoms which are different from each other in carbon number. In the formula (2-c), R ¹³ and R ²³ Are independently an alkylene group having 1 to 3 carbon atoms.

[Chemical Formula 6]

In the formula (2), the bonding position of the amino group (-NH ₂ ) on the benzene ring is not particularly limited, but is preferably a 3-aminophenyl structure or a 4-aminophenyl structure from the viewpoint of liquid crystal alignability, Aminophenyl structure. For example, the formula (2) is preferably any one of the following formulas (2-1), (2-2) and (2-3) . In the formulas (2-1), (2-2) and (2-3), Z ¹ , Z ² , R ³ and R ⁴ Is the definition and agreement in equation (2).

(7)

As specific examples of the formula (2), the compounds represented by the formulas (2-4) to (2-15) are shown. Among them, diamines represented by the above formulas (2-8) to (2-11) are particularly preferably used.

[Chemical Formula 8]

The content of the diamine represented by the formula (2) is preferably 10 to 70 mol% of the total diamine component, but is preferably 15 to 65 mol%, more preferably 20 to 60 mol% from the viewpoint of high rubbing resistance and low accumulated charge amount. mol% is particularly preferable.

≪ Other diamine compounds >

As long as the effect of the present invention is not impaired, the liquid crystal aligning agent of the present invention may contain, in addition to the diamine having a secondary amine at the polymerization reaction site or the diamine having a urea structure as the diamine component as a raw material of the polyamic acid, Other diamine compounds can also be contained. Specific examples of other diamine compounds are shown below.

2,3,5,6-tetramethyl-p-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, p-phenylenediamine, m-phenylenediamine, 2,4-dimethyl- Diaminodiphenol, 3,5-diaminophenol, 3,5-diaminobenzyl, 2,4-diaminophenol, 3,5-diaminophenol, Alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol, 4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dihydroxy-4,4'-diaminobiphenyl, 3,3'-difluoro-4,4'- Phenyl, 3,3'-trifluoromethyl-4,4'-diaminobiphenyl, 3,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 2,2'- Phenyl, 2,3'-diaminobiphenyl, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2'- Diaminodiphenylmethane, 2,3'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl, 3,4'-diaminodiphenyl ether, 2,2'-diaminodiphenyl ether, 2,3'-diaminodiphenyl ether, 4,4'-sulfonyldi aniline, 3,3'-sulfo Bis (4-aminophenyl) silane, dimethyl-bis (3-aminophenyl) silane, 4,4'-thiodi Aniline, 3,3'-thiodianiline, 4,4'-diaminodiphenylamine, 3,3'-diaminodiphenylamine, 3,4'-diaminodiphenylamine, 2,2'-dia Aminodiphenylamine, 2,3'-diaminodiphenylamine, N-methyl (4,4'-diaminodiphenyl) amine, N-methyl (3,3'- diaminodiphenyl) Methyl (2,2'-diaminodiphenyl) amine, N-methyl (2,3'-diaminodiphenyl) amine, 4,4 ' -Diaminobenzophenone, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 1,4-diaminonaphthalene, 2,2'-diaminobenzophenone, 2,3'-di Minobenzophenone, 1,5-diaminonaphthalene, 1,6-diamino-naphthalene There may be mentioned phthalene, 1,7-diaminonaphthalene, 1,8-diaminonaphthalene, 2,5-diaminonaphthalene, 2,6 diaminonaphthalene, 2,7-diaminonaphthalene, Bis (3-aminophenyl) ethane, 1,3-bis (4-aminophenyl) propane, 1,3- Propane, 1,4-bis (4-aminophenyl) butane, 1,4-bis (3-aminophenyl) butane, bis (Aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4 '- [1,4-phenylenebis (methylene)] dianiline, 4,4' - [ Phenylenebis (methylene)] dianiline, 3,4 '- [1,4-phenylenebis (methylene)] dianiline, 3,4' - [ ] Dianiline, 3,3 '- [1,4-phenylenebis (methylene)] dianiline, 3,3' - [1,3-phenylenebis Tylene)] dianiline, 1,4-phenylenebis [(4-aminophenyl) methanone], 1,4-phenylenebis [(3-aminophenyl) methanone], 1,3- (4-aminophenyl) methanone], 1,3-phenylenebis [(3-aminophenyl) methanone], 1,4-phenylenebis (3-aminobenzoate), 1,3-phenylene bis (4-aminobenzoate), 1,3-phenylene bis (3-aminobenzoate) Aminophenyl) isophthalate, N, N '- (1,4-phenylene) bis (4-aminobenzamide), bis N, N '- (1, 3-phenylene) bis (4-aminobenzamide), N, N' N, N'-bis (3-aminophenyl) terephthalamide, N, N'-bis (4-aminophenyl) terephthalamide, - bis (4-aminophenyl) iso Bis (4-aminophenoxy) diphenyl sulfone, 2, 3-aminophenyl) isophthalamide, N, Bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2'-bis (4 (Aminophenyl) hexafluoropropane, 2,2'-bis (3-aminophenyl) hexafluoropropane, 2,2'- Bis (3-aminophenyl) propane, and 2,2'-bis (3-aminophenyl) Bis (3-aminophenoxy) butane, 1, 5-bis (3-aminophenoxy) Bis (4-aminophenoxy) pentane, 1,6-bis (4-aminophenoxy) pentane, 1,6-bis ) Hexane, 1,7-bis (4-aminophenoxy) heptane, 1,7- Heptane, 1,8-bis (4-aminophenoxy) octane, 1,8-bis Bis (3-aminophenoxy) nonane, 1,10- (4-aminophenoxy) decane, 1,10- Dodecane, 1,12- (3-aminophenoxy) undecane, 1,12- (4-aminophenoxy) dodecane, bis (4-aminocyclohexyl) Methane, bis (4-amino-3-methylcyclohexyl) methane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12- .

The other diamine compounds exemplified above can be used singly or in combination of two or more kinds depending on the properties such as volume resistivity, rubbing resistance, ion density characteristics, transmittance, liquid crystal orientation, voltage holding property, They may be used in combination.

≪ Tetracarboxylic acid dianhydride having alicyclic structure or aliphatic structure >

The tetracarboxylic acid dianhydride having an alicyclic structure or aliphatic structure contained as an essential component in the tetracarboxylic acid dianhydride component, which is a raw material of the polyamic acid contained in the liquid crystal aligning agent of the present invention, 3). ≪ / RTI > It is needless to say that the tetracarboxylic acid dianhydride component may be replaced with tetracarboxylic acid dianhydride represented by the formula (3) in place of the tetracarboxylic acid dianhydride represented by the formula (3) Or a tetracarboxylic acid dianhydride having an alicyclic structure or an aliphatic structure other than the carboxylic acid dianhydride. The tetracarboxylic acid dianhydride having an alicyclic structure or an aliphatic structure may contain a tetracarboxylic acid dianhydride other than the tetracarboxylic dianhydride having an alicyclic structure or an aliphatic structure.

Here, in the formula (3), R ⁵ Represents a tetravalent hydrocarbon group having an alicyclic structure or an aliphatic structure. The alicyclic structure is a structure having a carbon ring having no aromaticity such as a cycloalkane, a cycloalkene or the like. The aliphatic structure means a structure having a chain type hydrocarbon group such as a paraffinic hydrocarbon group, an olefinic hydrocarbon group or an acetylenic hydrocarbon group (for example, the total number of carbon atoms of the chain type hydrocarbon group is 4 or more) to be. Specific examples of R ⁵ include quadrivalent groups represented by the following formulas (3-1) to (3-30).

[Chemical Formula 9]

[Chemical formula 10]

(11)

[Chemical Formula 12]

In the polyamic acid contained in the liquid crystal aligning agent of the present invention, it is preferable that at least 50 mol%, preferably at least 70 mol%, of the tetracarboxylic acid dianhydride component satisfies the formulas (3-1) to (3-25) R < ⁵ > having an alicyclic structure or an aliphatic structure such as the formula (3-30) . With such a composition, the voltage holding ratio of the liquid crystal display element can be improved, and the amount of accumulated charge can be reduced in particular. Also, R ⁵ (3-1), (3-2), (3-6), (3-25) and (3-30) among the alicyclic structure or aliphatic structure selected from the group consisting of Tetracarboxylic acid dianhydride is used, a liquid crystal alignment film having a smaller accumulated charge amount can be obtained, which is preferable.

The tetracarboxylic acid dianhydride component preferably contains an aromatic tetracarboxylic acid dianhydride. This makes it possible to particularly improve the orientation of the liquid crystal alignment film. At this time, if too much aromatic tetracarboxylic acid dianhydride is used relative to the total amount of the tetracarboxylic acid dianhydride component, the rubbing resistance is deteriorated, which causes the display quality of the liquid crystal display element to deteriorate. Therefore, the aromatic tetracarboxylic acid dianhydride is preferably 50 mol% or less, more preferably 30 mol% or less, based on the total amount of the tetracarboxylic acid dianhydride component. Examples of the aromatic tetracarboxylic acid dianhydride include tetracarboxylic dianhydrides represented by the following formula (4). In formula (4), R < ⁶ > Is a group having an aromatic structure. An aromatic structure is a structure having an aromatic ring showing aromatics such as a benzene ring. Specific examples of R ⁶ include quaternary groups represented by the following formulas (3-31) to (3-47).

[Chemical Formula 13]

[Chemical Formula 14]

<Polymerization of polyamic acid>

A method of reacting the above-mentioned diamine component with a tetracarboxylic acid dianhydride component (hereinafter, simply referred to as tetracarboxylic acid dianhydride) to obtain the polyamic acid contained in the liquid crystal aligning agent of the present invention is not particularly limited, A known method can be applied. Generally, a polyamic acid can be prepared by mixing a diamine component and a tetracarboxylic acid dianhydride component in an organic solvent to effect a polymerization reaction.

As a method for mixing the tetracarboxylic acid dianhydride component and the diamine component in an organic solvent, a method in which a solution in which a diamine component is dispersed or dissolved in an organic solvent is stirred, and the tetracarboxylic acid dianhydride component is dispersed as it is or in an organic solvent A method in which a diamine component is added to a solution in which a tetracarboxylic acid dianhydride component is dispersed or dissolved in an organic solvent, a method in which a tetracarboxylic acid dianhydride component and a diamine component are alternately added, . When at least one of the tetracarboxylic acid dianhydride component and the diamine component is composed of a plurality of compounds, the polymerization reaction may be carried out in a state in which these plural kinds of components are mixed in advance, or the polymerization reaction may be performed individually and sequentially.

The temperature at which the tetracarboxylic acid dianhydride component and the diamine component are polymerized in an organic solvent is usually 0 to 150 占 폚, preferably 5 to 100 占 폚, more preferably 10 to 80 占 폚. If the temperature is higher, the polymerization reaction is terminated quickly, whereas if the temperature is too high, a polymer having a high molecular weight (polyamic acid) may not be obtained. The polymerization reaction can be carried out at an arbitrary injection concentration. However, if the injection concentration is too low, it becomes difficult to obtain a polymer having a high molecular weight. If the injection concentration is too high, the viscosity of the reaction liquid becomes too high, , Preferably from 1 to 50 mass%, and more preferably from 5 to 30 mass%. In addition, an initial stage of the polymerization reaction may be carried out at a high concentration, and then an organic solvent may be added. The injection concentration is the concentration of the total mass of the tetracarboxylic acid dianhydride component and the diamine component.

The organic solvent used in the reaction is not particularly limited as long as it dissolves the produced polyamic acid. Specific examples include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, Sulfoxide,? -Butyrolactone, and the like. These may be used alone or in combination. Further, even a solvent that does not dissolve the polyamic acid may be used in combination with the solvent insofar as the produced polyamic acid does not precipitate.

Water in the organic solvent inhibits the polymerization reaction, and further causes hydrolysis of the produced polyamic acid. Therefore, it is preferable to use an organic solvent which is dehydrated and dried as much as possible.

The molar ratio of the tetracarboxylic acid dianhydride component to the diamine component used in the polymerization reaction for obtaining the polyamic acid is preferably 1: 0.8 to 1: 1.2, and the molar ratio of the tetracarboxylic acid dianhydride component to the diamine component is preferably 1: Is increased. If the molecular weight of the polyamic acid is too small, the strength of the coating film obtained therefrom may be insufficient. Conversely, if the molecular weight of the polyamic acid is too large, the viscosity of the liquid crystal aligning agent produced thereby becomes too high, And the uniformity of the coating film may be deteriorated. Therefore, the weight average molecular weight of the polyamic acid used in the liquid crystal aligning agent of the present invention is preferably from 2,000 to 500,000, more preferably from 5,000 to 300,000.

<Liquid Crystal Aligner>

The liquid crystal aligning agent of the present invention contains at least one kind of polyamic acid obtained as described above. By using such a liquid crystal aligning agent containing a polyamic acid obtained by reacting such a specific diamine component with a specific tetracarboxylic acid dianhydride component, it is possible to obtain a liquid crystal alignment layer having good liquid crystal alignability and rubbing resistance, And the liquid crystal alignment film having a small accumulated charge in the FFS mode liquid crystal display element can be obtained. The liquid crystal aligning agent of the present invention usually is a coating liquid obtained by dissolving the polyamic acid in an organic solvent, but the liquid crystal aligning agent of the present invention may be in a different form as long as a uniform thin film can be formed on the substrate .

The liquid crystal aligning agent of the present invention may contain a tetracarboxylic acid dianhydride component containing a tetracarboxylic acid dianhydride having the above-described alicyclic structure or aliphatic structure as the polymer component, as long as the effect of the present invention is not impaired. , A diamine having a urea structure, and a diamine component containing a diamine having a secondary amine at the polymerization reaction site, as well as a polymer having another structure. As the polymer having another structure, polyamic acid having a molecular structure different from that of the above-mentioned polyamic acid, polyamic acid ester, and the like can be given. Taking into consideration that the obtained polyimide film (liquid crystal alignment film) realizes desired properties, the tetracarboxylic acid dianhydride component containing the tetracarboxylic acid dianhydride having the above-described alicyclic structure or aliphatic structure and the urea structure , And the diamine component containing a diamine having a secondary amine at the polymerization reaction site, relative to the total amount of the polymer component (100 mol%), to 10 mol% to 80 mol% .

The organic solvent contained in the liquid crystal aligning agent is not particularly limited as long as it dissolves a polymer component such as a polyamic acid contained therein. Specific examples of the organic solvent include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, , N-vinylpyrrolidone, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethylsulfoxide,? -Butyrolactone or 1,3-dimethyl-imidazolidinone. These may be used alone or in combination of two or more.

In addition, even a solvent which does not dissolve the polymer component alone can be mixed with the liquid crystal aligning agent of the present invention so far as the polymer component is not precipitated. Particularly, it is preferable to use ethylcellosolve, butylcellosolve, ethylcarbitol, butylcarbitol, ethylcarbitol acetate, ethylene glycol, 1-methoxy-2-propanol, 1- Propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol- A solvent having a low surface tension such as dipropylene glycol, 2- (2-ethoxypropoxy) propanol, lactic acid methyl ester, lactic acid ethyl ester, lactic acid N-propyl ester, lactic acid N-butyl ester and lactic acid i- , It is known that the uniformity of the coating film on the substrate is improved by mixing them. Therefore, these solvents may be used singly or in combination.

The amount of the solvent having a low surface tension is preferably from 5 to 80% by mass, more preferably from 20 to 60% by mass, based on the entire solvent contained in the liquid crystal aligning agent.

The liquid crystal aligning agent of the present invention may contain various additives in addition to the above-mentioned polymer component and organic solvent.

For example, as an additive for improving film thickness uniformity and surface smoothness, a fluorine-based surfactant, a silicon-based surfactant, or a nonionic surface-active agent can be given.

(Manufactured by Tohchem Products), Megafac F171, F173, R-30 (manufactured by Dainippon Ink & Chemicals, Inc.), Florad FC430 and FC431 (manufactured by Sumitomo 3M Ltd.), Asahi Guard AG710 , Surplon S-382, SC101, SC102, SC103, SC104, SC105, and SC106 (manufactured by Asahi Glass Co., Ltd.). The use ratio of these surfactants is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass, per 100 parts by mass of the polymer component contained in the liquid crystal aligning agent.

Specific examples of the additive for improving the adhesion between the liquid crystal alignment film and the substrate include a functional silane-containing compound and an epoxy group-containing compound.

For example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2-aminoethyl) -3 3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxy (3-aminopropyl) Aminopropyltriethoxysilane, N-trimethoxysilylpropyltriethoxysilane, N-trimethoxysilylpropyltriethoxysilane, N-trimethoxysilylpropyltriethoxysilane, N-trimethoxysilylpropyltriethoxysilane, Amine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl Acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N- Bis (oxyethylene) -3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N- Aminopropyltriethoxysilane, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neo Pentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6 Tetraglycidyl-2,4-hexanediol, N, N, N ', N', -tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N-diglycidylamino Methyl) cyclohexane or N, N, N ', N', -tetraglycidyl-4,4'-diaminodiphenylmethane and the like. The amount of these compounds to be added is preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass, per 100 parts by mass of the polymer component contained in the liquid crystal aligning agent. If the amount is less than 0.1 part by mass, the effect of improving the adhesion can not be expected, and if it is more than 30 parts by mass, the liquid crystal alignability may deteriorate.

A dielectric or conductive material may be added to the liquid crystal aligning agent of the present invention for the purpose of changing electric characteristics such as dielectric constant and conductivity of the liquid crystal alignment film. For the purpose of increasing the hardness and density of the film as a liquid crystal alignment film, A compound or the like may be added.

The concentration of the solid content in the liquid crystal aligning agent of the present invention can be appropriately changed according to the thickness of the intended liquid crystal alignment film but it is possible to form a coating film without defects and to obtain an appropriate film thickness as the liquid crystal alignment film Is preferably 1 to 20% by mass, and more preferably 2 to 10% by mass.

&Lt; Liquid crystal alignment film &

The liquid crystal aligning agent of the present invention can be used as a liquid crystal alignment film without alignment treatment in the case where the liquid crystal aligning agent is applied to a substrate and then subjected to an orientation treatment by rubbing treatment or light irradiation or to a vertically aligned liquid crystal display element Is used. The substrate to be used at this time is not particularly limited as long as it is a substrate having high transparency. A glass substrate, a plastic substrate such as an acrylic substrate and a polycarbonate substrate, or the like can be used. However, ITO (Indium Tin Oxide) It is preferable from the viewpoint of simplification of the process. In the reflection type liquid crystal display device, an opaque substrate such as a silicon wafer can be used as long as it is a substrate on only one side. As the electrode in this case, a material that reflects light such as aluminum may be used.

The method of applying the liquid crystal aligning agent is not particularly limited, but industrially, screen printing, offset printing, flexographic printing, inkjet, or the like is generally used. As other coating methods, there are a dip method, a method using a roll coater, a slit coater, a spinner or the like, and they may be appropriately selected from these depending on the purpose.

The baking of the substrate coated with the liquid crystal aligning agent can be carried out at any temperature of 100 to 350 ° C, preferably 150 to 300 ° C, more preferably 180 to 250 ° C. The polyamic acid in the liquid crystal aligning agent and the polyamic acid ester which is optionally contained vary in the conversion rate to the polyimide depending on the firing temperature, but the liquid crystal aligning agent of the present invention does not necessarily need to be imidized to 100%. Therefore, the firing time can be set to an arbitrary time. However, if the firing time is too short, display defects may occur due to the influence of the residual solvent, so that the firing time is preferably 5 to 60 minutes, and more preferably 10 to 40 minutes.

When the thickness of the coated film after firing is too large, the power consumption of the liquid crystal display element is deteriorated. When the thickness is too thin, the reliability of the liquid crystal display element may be deteriorated. Therefore, the thickness is preferably 5 to 300 nm, more preferably 10 To 100 nm. When the liquid crystal is horizontally oriented or tilted, the coated film after firing is treated by rubbing, polarized ultraviolet irradiation, or the like.

<Liquid crystal display element>

The liquid crystal display element of the present invention is obtained by obtaining a substrate on which a liquid crystal alignment film is formed from the liquid crystal aligning agent of the present invention by the above-described technique, and then a liquid crystal cell is produced by a known method to form a liquid crystal display element.

An example of the manufacture of a liquid crystal cell is as follows. First, a pair of substrates on which a liquid crystal alignment film is formed are prepared. Then, spacers are sprayed on the liquid crystal alignment film of one substrate so that the liquid crystal alignment film surface is inward, and the other substrate is bonded. Then, the liquid crystal is injected under reduced pressure and sealed. Alternatively, the liquid crystal may be dropped on the surface of the liquid crystal alignment film spreading the spacer, and then the substrate may be bonded and sealed. The thickness of the spacer at this time is preferably 1 to 30 占 퐉, more preferably 2 to 10 占 퐉.

The liquid crystal display device manufactured using the liquid crystal aligning agent of the present invention can be preferably used for a liquid crystal television with excellent display quality as well as high reliability and high precision on a large screen.

As described above, by using the liquid crystal aligning agent of the present invention as described above, it is possible to obtain a liquid crystal alignment film having less damage and scraping on the film surface during rubbing treatment, good liquid crystal alignability, and low ion density when used as a liquid crystal display device .

The liquid crystal alignment film obtained by using the liquid crystal aligning agent of the present invention has a remarkably high volume resistivity as compared with general polyamic acid, either due to the influence of the secondary amine structure and the urea structure. The value is equivalent to the soluble polyimide which is said to have a high volume resistivity. However, a FFS mode liquid crystal display element using a liquid crystal alignment film obtained by using the liquid crystal aligning agent of the present invention can provide a high-quality liquid crystal display element having a small accumulated charge amount and a low residual image level. That is, the liquid crystal alignment film obtained by using the liquid crystal aligning agent of the present invention has a high volume resistivity but can suppress the occurrence of the afterimage because the amount of accumulated electric charge is very small, resulting in a problem that it takes time to remove the afterimage It can be said that there is no.

Further, the liquid crystal aligning agent of the present invention can be used not only for a liquid crystal alignment film to be oriented by rubbing treatment but also for forming a liquid crystal alignment film which is optically oriented, that is, a liquid crystal alignment film which is subjected to orientation treatment by light irradiation.

Example

Hereinafter, the present invention will be described in further detail with reference to examples, but the present invention is not construed as being limited thereto.

The abbreviations and structures of the compounds used in this Synthesis Example are shown below.

CA-1: 1,2,3,4-Cyclobutane tetracarboxylic acid dianhydride

CA-2: pyromellitic acid dianhydride

CA-3: bicyclo [3,3,0] octane-2,4,6,8-tetracarboxylic acid dianhydride

DA-1: 4- (2- (methylamino) ethyl) aniline

DA-2: 1,3-bis (4-aminophenetyl) urea

DA-3: 3 - ((methylamino) methyl) aniline

DA-4: 1,5-bis (4-aminophenoxy) pentane

DA-5: p-phenylenediamine

DA-6: 4,4'-diaminodiphenylamine

[Chemical Formula 15]

(In the formula, Me represents a methyl group.)

Hereinafter, evaluation methods of the viscosity, the solid concentration, the voltage holding ratio, the ion density, the volume resistivity, the measurement method of the residual DC, the rubbing resistance and the liquid crystal orientation and the evaluation method of the conventional system liquid crystal cell, the transverse electric field liquid crystal cell (FFS mode liquid crystal cell) Respectively.

[Measurement of viscosity]

The viscosity of the polyamic acid solution used in the synthesis example or the comparative synthesis example was 1.1 ml of a sample amount, the cone TE-1 (1 ° 34 ', R24), and the viscosity of the polyamic acid solution was measured using an E-type viscometer TVE-22H (Toki Industry Co., And the temperature was measured at 25 캜.

[Measurement of solid content concentration]

In the synthesis examples or comparative synthesis examples, the solid content concentration of the polyamic acid solution was calculated as follows.

Aluminum cup with handle. About 1.1 g of polyamic acid solution was weighed in an oven DNF400 (manufactured by Yamato), heated at 200 DEG C for 2 hours, left at room temperature for 5 minutes, and the weight of the solid remaining in the aluminum cup was weighed. The solid content concentration was calculated from the weight of the solid content and the value of the original solution weight.

[Evaluation of rub resistance]

The polyamic acid solution obtained in Synthesis Example or Comparative Synthesis Example was filtered with a filter of 1.0 占 퐉 and then coated on a glass substrate having a transparent electrode formed thereon by spin coating and dried on a hot plate at 50 占 폚 for 5 minutes, Followed by baking for minute to obtain a polyimide film having a film thickness of 100 nm. This polyimide film was rubbed with a rayon cloth (roller diameter 120 mm, roller rotation number 1000 rpm, moving speed 20 mm / sec, indentation length 0.6 mm). The presence or absence of damage on the surface of the polyimide membrane was observed with a confocal laser microscope (magnification: 10 times). "No damage" was judged as "good", and the case of damage was judged as "defective".

[Manufacturing of conventional liquid crystal cell]

The polyamic acid solution obtained in Synthesis Example or Comparative Synthesis Example was filtered with a filter of 1.0 占 퐉 and then applied on a glass substrate on which an ITO beta electrode was formed (one having an ITO film formed on the entire surface on a glass substrate) Dried on a hot plate at 50 DEG C for 5 minutes, and then baked at 230 DEG C for 30 minutes to obtain a polyimide film having a film thickness of 100 nm. This polyimide film was rubbed with a rayon cloth (roller diameter: 120 mm, roller rotation speed: 1000 rpm, moving speed: 20 mm / sec, indentation length: 0.3 mm), ultrasonic irradiation was conducted for 1 minute in pure water After removing water droplets by an air blow, the substrate was dried at 80 ° C for 15 minutes to obtain a substrate having a liquid crystal alignment film formed thereon. Two substrates each having such a liquid crystal alignment film formed thereon were prepared, spacers having a size of 6 mu m were provided on the liquid crystal alignment film surface of one of the substrates, and the rubbing directions of the two substrates were combined so as to be antiparallel. And an empty cell having a cell gap of 6 탆 was produced. A liquid crystal (MLC-2041, manufactured by Merck) was injected into the cell under vacuum at room temperature, and the injection port was sealed to obtain an anti-parallel liquid crystal cell.

[Liquid crystal orientation property evaluation]

The alignment state of the former system liquid crystal cell manufactured as described above was observed with a polarizing microscope to determine that there was no alignment defect and &quot; defective &quot;

[Measurement of voltage retention rate]

Using the conventional system liquid crystal cell manufactured as described above, measurement was carried out with a VHR-1 type voltage sustained-rate measuring system manufactured by Toyo Technica. The measurement was carried out by applying an alternating voltage of ± 4 V for 60 μsec and measuring the voltage after 16.67 m seconds, and the variation from the initial value was calculated as the voltage holding ratio. At the time of measurement, the temperature of the liquid crystal cell was set at 60 DEG C, 98% or more was judged as "good", and less than 98% was judged as "poor".

[Ion density measurement]

Using the conventional liquid crystal cell manufactured as described above, measurement was carried out with a 6254-type liquid crystal physical property evaluation system manufactured by Toyo Technica. A triangular wave of ± 10 V and 0.01 Hz was applied and the area corresponding to the ion density of the obtained waveform was calculated by the triangular approximation method to obtain the ion density. During the measurement, the temperature of the liquid crystal cell was set at 23 DEG C, "less than 100 pC / cm &quot; was defined as" good ", and 100 pC / cm &

[Measurement of volume resistivity]

The polyamic acid solution obtained in Synthesis Example or Comparative Synthesis Example was filtered with a filter of 1.0 占 퐉, spin-coated on a glass substrate on which ITO transparent electrodes were formed, dried on a hot plate at 70 占 폚 for 2 minutes, And a coating film (liquid crystal alignment film) having a film thickness of about 220 nm was formed. Aluminum was deposited on the surface of the coating film through a mask, and an upper electrode (aluminum electrode) of 1.0 mm? Was formed to obtain a sample for measuring the volume resistivity. A voltage of 5 V was applied between the ITO electrode and the aluminum electrode of this sample, and the current value after 180 seconds from the voltage application was measured. The volume resistivity was calculated from this value, the electrode area, and the measured value of the film thickness.

[Fabrication of FFS mode liquid crystal cell]

The polyamic acid solution obtained in Synthesis Example or Comparative Synthesis Example was filtered with a filter having a size of 1.0 mu m, and then an IZO (Indium Zinc Oxide) beta electrode having a thickness of 50 nm was formed on the first layer, a silicon nitride insulating film having a thickness of 500 nm, On the third layer, a 50 nm thick IZO interdigital electrode (electrode width: 3 mu m, electrode gap: 6 mu m) was coated on a substrate capable of FFS mode driving by spin coating and dried on a hot plate at 50 DEG C for 5 minutes, Followed by baking at 230 DEG C for 30 minutes to obtain a polyimide film having a film thickness of 100 nm. This polyimide film was rubbed with a rayon cloth (roller diameter: 120 mm, roller rotation speed: 500 rpm, moving speed: 30 mm / sec, press-in length: 0.3 mm, rubbing direction: 10 ° with respect to the third layer IZO comb- Direction), cleaned by ultrasonic irradiation for 1 minute in pure water, water droplets were removed by an air blow, and then dried at 80 DEG C for 15 minutes to obtain a substrate having a liquid crystal alignment film formed thereon. A polyimide film was formed in the same manner as described above on a glass substrate having a columnar spacer having a height of 4 占 퐉 in which no electrode was formed as a counter substrate and a liquid crystal alignment film &Lt; / RTI &gt; These two substrates were combined so that the rubbing directions of the two substrates were antiparallel to each other, leaving a liquid crystal injection hole and sealing the periphery, thereby manufacturing empty cells having a cell gap of 4 탆 . A liquid crystal (ZLI-4792, manufactured by Merck) was injected into the cell under vacuum at room temperature, and the injection port was sealed to obtain an anti-parallel liquid crystal cell.

[Residual DC (dielectric absorption method) measurement]

Using the FFS mode liquid crystal cell manufactured as described above, measurement was carried out with a 6254-type liquid crystal physical property evaluation system manufactured by Toyo Technica. The measurement was performed by applying a DC voltage of +4 V for 30 minutes, then discharging for 1 second, and then measuring the amount of residual DC for 60 minutes. At the time of measurement, the temperature of the liquid crystal cell was set to 60 DEG C, the residual DC amount after 60 minutes from the discharge was rated as &quot; good &quot;

(Synthesis Example 1)

2.83 g (18.8 mmol) of DA-1, 5.61 g (18.8 mmol) of DA-2 and 2.70 g (9.40 mmol) of DA-4 were placed in a 200 ml four- necked flask equipped with a stirrer and a nitrogen- , And 126 g of N-methyl-2-pyrrolidone were added and dissolved by stirring while nitrogen was being supplied. 8.84 g (45.1 mmol) of CA-1 was added while stirring the diamine solution, N-methyl-2-pyrrolidone was further added thereto so as to have a solid content concentration of 10 mass%, and the mixture was stirred at room temperature for 2 hours Followed by stirring to obtain a solution of polyamic acid (A-1). The viscosity of the polyamic acid solution at 25 캜 was 135 mPa..

21.2 g of this polyamic acid solution was taken in a 50 ml Erlenmeyer flask with stirring, and 2.67 g of N-methyl-2-pyrrolidone, 1.0% by mass of 3-aminopropyltriethoxysilane, 2.08 g of a solution of Don and 8.66 g of butyl cellosolve were added and stirred for 2 hours to obtain a polyamic acid solution having a solid concentration of 6.0% by mass.

(Synthesis Example 2)

3.55 g (23.6 mmol) of DA-1 and 10.6 g (35.4 mmol) of DA-2 were placed in a 300-ml four-necked flask equipped with a stirrer and a nitrogen inlet tube and N-methyl-2-pyrrolidone 136 g, and dissolved with stirring while nitrogen was being supplied. 11.3 g (57.6 mmol) of CA-1 was added while stirring the diamine solution, N-methyl-2-pyrrolidone was further added thereto so as to have a solid content concentration of 10 mass%, and the mixture was stirred at room temperature for 5 hours Followed by stirring to obtain a solution of polyamic acid (A-2). The viscosity of the polyamic acid solution at 25 캜 was 156 mPa..

This polyamic acid solution (168 g) was taken in a 500 ml Erlenmeyer flask with stirring and 55.1 g of N-methyl-2-pyrrolidone, 1.0 mass% of 3-aminopropyltriethoxysilane, 16.5 g of a Don solution and 60.0 g of butyl cellosolve were added and stirred for 2 hours to obtain a polyamic acid solution having a solid content concentration of 5.7% by mass.

(Synthesis Example 3)

72.1 g (480 mmol) of DA-1, 71.5 g (240 mmol) of DA-2 and 137 g (480 mmol) of DA-4 were taken in a 5 L separable flask equipped with a stirrer and a nitrogen- And 3200 g of N-methyl-2-pyrrolidone were added and dissolved by stirring while nitrogen was being supplied. While stirring the diamine solution, 227 g (1.16 mol) of CA-1 was added, and N-methyl-2-pyrrolidone was further added thereto so as to have a solid content concentration of 10 mass% Followed by stirring to obtain a solution of polyamic acid (A-3). The viscosity of the polyamic acid solution at 25 캜 was 155 mPa s.

176 g of this polyamic acid solution was taken in a 500 ml Erlenmeyer flask with stirring and 48.0 g of N-methyl-2-pyrrolidone, 1.0% by mass of 3-aminopropyltriethoxysilane, 16.5 g of a Don solution and 60.0 g of butyl cellosolve were added and stirred for 2 hours to obtain a polyamic acid solution having a solid content concentration of 5.7% by mass.

(Synthesis Example 4)

1.68 g (11.2 mmol) of DA-1, 6.68 g (22.4 mmol) of DA-2, and 6.42 g (22.4 mmol) of DA-4 were placed in a 300 ml four-necked flask equipped with a stirrer and a nitrogen- , And 157 g of N-methyl-2-pyrrolidone were added and dissolved by stirring while nitrogen was being supplied. To this diamine solution, 10.6 g (54.0 mmol) of CA-1 was added while N-methyl-2-pyrrolidone was further added so as to have a solid content concentration of 10 mass%, and the mixture was stirred at room temperature for 5 hours Followed by stirring to obtain a solution of polyamic acid (A-4). The viscosity of this polyamic acid solution at 25 캜 was 148 mPa..

172 g of this polyamic acid solution was taken in a 500 ml Erlenmeyer flask with stirring, and 51.6 g of N-methyl-2-pyrrolidone, 1.0 mass% of N-methyl-2-pyrrolidone 16.5 g of a Don solution and 60.0 g of butyl cellosolve were added and stirred for 2 hours to obtain a polyamic acid solution having a solid content concentration of 5.6% by mass.

(Synthesis Example 5)

5.41 g (36.0 mmol) of DA-1, 3.59 g (12.0 mmol) of DA-2, and 3.44 g (12.0 mmol) of DA-4 were placed in a 300 ml four-necked flask equipped with a stirrer and a nitrogen- And 151 g of N-methyl-2-pyrrolidone were added and dissolved by stirring while nitrogen was being supplied. 11.5 g (58.7 mmol) of CA-1 was added while stirring the diamine solution, N-methyl-2-pyrrolidone was further added thereto so as to have a solid content concentration of 10 mass%, and the mixture was stirred at room temperature for 2 hours Followed by stirring to obtain a solution of polyamic acid (A-5). The viscosity of this polyamic acid solution at 25 캜 was 159 mPa..

215 g of the polyamic acid solution was taken in a 500 ml Erlenmeyer flask, and 43.2 g of N-methyl-2-pyrrolidone, 1.0% by mass of 3-aminopropyltriethoxysilane, 20.9 g of a Don solution and 69.7 g of butyl cellosolve were added and stirred for 2 hours to obtain a polyamic acid solution having a solid concentration of 6.0% by mass.

(Synthesis Example 6)

3.30 g (22.0 mmol) of DA-1, 16.4 g (55.0 mmol) of DA-2, and 9.45 g (33.0 mmol) of DA-4 were placed in a 500 ml four-necked flask equipped with a stirrer and a nitrogen- And 229 g of N-methyl-2-pyrrolidone were added and dissolved by stirring while nitrogen was being supplied. 15.1 g (77.0 mmol) of CA-1 and 7.79 g (31.1 mmol) of CA-3 were added while stirring the diamine solution, and N-methyl-2-pyrrolidone And the mixture was stirred under a nitrogen atmosphere at 40 占 폚 for 40 hours to obtain a solution of polyamic acid (A-6). The viscosity of the polyamic acid solution at 25 캜 was 295 mPa..

751 g of this polyamic acid solution was taken in a 3 L Erlenmeyer flask, and 461 g of N-methyl-2-pyrrolidone, 1.0% by mass of 3-aminopropyltriethoxysilane, 92.1 g of a Don solution and 225 g of butyl cellosolve were added and stirred for 2 hours to obtain a polyamic acid solution having a solid content concentration of 6.0% by mass.

(Synthesis Example 7)

1.57 g (10.4 mmol) of DA-1 and 4.65 g (15.6 mmol) of DA-2 were placed in a 100-ml four-necked flask equipped with a stirrer and a nitrogen inlet tube and N-methyl-2-pyrrolidone 57.9 g, and dissolved with stirring while nitrogen was being supplied. 3.44 g (17.6 mmol) of CA-1 and 1.70 g (7.80 mmol) of CA-2 were added while stirring the diamine solution, and N-methyl-2-pyrrolidone And the mixture was stirred under nitrogen atmosphere at room temperature for 5 hours to obtain a solution of polyamic acid (A-7). The viscosity of the polyamic acid solution at 25 캜 was 196 mPa s.

27.2 g of N-methyl-2-pyrrolidone, and 18.0 g of butyl cellosolve were added to 45.1 g of this polyamic acid solution in a 100 ml Erlenmeyer flask with stirring, followed by stirring for 2 hours to obtain a solution having a solid concentration of 6.0% A polyamic acid solution was obtained.

(Synthesis Example 8)

3.49 g (23.2 mmol) of DA-1, 6.92 g (23.2 mmol) of DA-2, and 2.31 g (11.6 mmol) of DA-6 were placed in a 200 ml four-necked flask equipped with a stirrer and a nitrogen- And 125 g of N-methyl-2-pyrrolidone were added and dissolved by stirring while nitrogen was being supplied. 9.10 g (46.4 mmol) of CA-1 and 2.57 g (10.3 mmol) of CA-3 were added while stirring the diamine solution, and N-methyl-2-pyrrolidone And the mixture was stirred at 40 占 폚 for 24 hours under a nitrogen atmosphere to obtain a solution of polyamic acid (A-8). The viscosity of the polyamic acid solution at 25 캜 was 348 mPa..

19.8 g of this polyamic acid solution was taken in a 50 ml Erlenmeyer flask with stirring, to which 8.07 g of N-methyl-2-pyrrolidone, 1.0 mass% of N-methyl-2-pyrrolidone 2.42 g of the Don's solution and 10.1 g of butyl cellosolve were added and stirred for 2 hours to obtain a polyamic acid solution having a solid concentration of 6.0% by mass.

(Synthesis Example 9)

1.68 g (11.2 mmol) of DA-1, 2.51 g (8.40 mmol) of DA-2, and 0.91 g (8.40 mmol) of DA-5 were placed in a 100 ml four-necked flask equipped with a stirrer and a nitrogen- And 43 g of N-methyl-2-pyrrolidone were added and dissolved with stirring while nitrogen was being supplied. 5.30 g (27.0 mmol) of CA-1 was added while stirring the diamine solution, N-methyl-2-pyrrolidone was further added thereto so as to have a solid content concentration of 10 mass%, and the mixture was stirred at room temperature for 2 hours Followed by stirring to obtain a solution of polyamic acid (A-9). The viscosity of this polyamic acid solution at 25 캜 was 125 mPa..

54.0 g of this polyamic acid solution was taken in a 100 ml Erlenmeyer flask with stirring, and 3.60 g of? -Butyrolactone, 5.40 g of a? -Butyrolactone solution of 1.0% by mass of 3-aminopropyltriethoxysilane, 27.0 g of rosorb was added and stirred for 2 hours to obtain a polyamic acid solution having a solid content concentration of 6.0% by mass.

(Synthesis Example 10)

1.64 g (12.0 mmol) of DA-3 and 5.38 g (18.0 mmol) of DA-2 were placed in a 100 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube, g, and dissolved with stirring while nitrogen was being supplied. 5.68 g (29.0 mmol) of CA-1 was added while stirring the diamine solution, and N-methyl-2-pyrrolidone was further added thereto so as to have a solid content concentration of 12 mass% Followed by stirring for a time period to obtain a solution of polyamic acid (A-10). The viscosity of the polyamic acid solution at 25 캜 was 211 mPa..

This polyamic acid solution (47.1 g) was taken in a 100 ml Erlenmeyer flask, and 28.3 g of N-methyl-2-pyrrolidone and 18.7 g of butyl cellosolve were added and stirred for 2 hours to obtain a solution having a solid concentration of 6.0% A polyamic acid solution was obtained.

(Comparative Synthesis Example 1)

31.7 g (294 mmol) of DA-5 and 37.6 g (126 mmol) of DA-2 were taken in a 2-liter separable flask equipped with a stirrer and a nitrogen inlet tube and N-methyl-2-pyrrolidone 864 g, and dissolved with stirring while nitrogen was being supplied. 78.2 g (399 mmol) of CA-1 was added while stirring the diamine solution, N-methyl-2-pyrrolidone was further added thereto so as to have a solid content concentration of 12 mass%, and the mixture was stirred at room temperature for 6 hours Followed by stirring to obtain a solution of polyamic acid (B-1). The viscosity of this polyamic acid solution at 25 캜 was 308 mPa..

1155 g of this polyamic acid solution was taken in a 3 L Erlenmeyer flask, and 482 g of N-methyl-2-pyrrolidone, 1.0% by mass of 3-aminopropyltriethoxysilane, 133 g of the Don solution and 442 g of butyl cellosolve were added and stirred for 3 hours to obtain a polyamic acid solution having a solid content concentration of 6.0% by mass.

(Comparative Synthesis Example 2)

5.25 g (35.0 mmol) of DA-1 was added to a 100 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube, 60.5 g of N-methyl-2-pyrrolidone was added, . 6.79 g (34.7 mmol) of CA-1 was added while stirring the diamine solution, N-methyl-2-pyrrolidone was further added thereto so as to have a solid content concentration of 12 mass%, and the mixture was stirred at room temperature for 4.5 hours Followed by stirring to obtain a solution of polyamic acid (B-2). The viscosity of the polyamic acid solution at 25 캜 was 275 mPa..

47.0 g of this polyamic acid solution was taken in a 100 ml Erlenmeyer flask with stirring and 28.2 g of N-methyl-2-pyrrolidone and 18.8 g of butyl cellosolve were added and stirred for 2 hours to obtain a solution having a solid concentration of 6.0% A polyamic acid solution was obtained.

(Comparative Synthesis Example 3)

3.16 g (21.0 mmol) of DA-1 and 2.69 g (9.00 mmol) of DA-2 were taken in a 100-ml four-necked flask equipped with a stirrer and a nitrogen inlet tube and N-methyl-2-pyrrolidone 62.3 g, and dissolved with stirring while nitrogen was being supplied. While stirring the diamine solution, 6.28 g (29.7 mmol) of CA-2 was added, N-methyl-2-pyrrolidone was further added so that the solid content concentration became 12 mass%, and the mixture was stirred at room temperature for 5 hours Followed by stirring to obtain a solution of polyamic acid (B-3). The viscosity of the polyamic acid solution at 25 캜 was 65 mPa s.

29.8 g of N-methyl-2-pyrrolidone and 19.8 g of butyl cellosolve were added to 49.7 g of the polyamic acid solution, and the mixture was stirred for 2 hours to obtain a solution having a solid concentration of 6.0% by mass A polyamic acid solution was obtained.

Table 1 shows the formulations in the above Synthesis Examples and Comparative Synthesis Examples.

&Lt; Example 1 &gt;

Each evaluation and each measurement of the polyamic acid solution containing the polyamic acid (A-1) obtained in Synthesis Example 1 showed that the rubbing resistance was "good", the liquid crystal orientation was "good" and the voltage retention was 98.8% , The volume resistivity was 1.9 × 10 ¹⁵ Ω · cm, the residual DC was 1.05 V after 10 minutes, 1.08 V after 20 minutes, and 1.11 V after 60 minutes. .

&Lt; Example 2 &gt;

Each evaluation and each measurement of the polyamic acid solution containing the polyamic acid (A-2) obtained in Synthesis Example 2 showed that the rubbing resistance was "good", the liquid crystal alignability was "good" and the voltage retention was 98.7% Good "at 0 pC / cm 2 for the ion density, 0.87 V after 10 minutes, 0.96 V after 20 minutes, and 0.99 V after 60 minutes.

&Lt; Example 3 &gt;

Each evaluation and each measurement of the polyamic acid solution containing the polyamic acid (A-3) obtained in Synthesis Example 3 showed that the rubbing resistance was "good", the liquid crystal alignability was "good" and the voltage retention was 98.4% Good "for the ion density of 59 pC / cm 2, 0.69 V after 10 minutes of residual DC, 0.74 V after 20 minutes, and 0.81 V after 60 minutes.

<Example 4>

Each evaluation and each measurement of the polyamic acid solution containing the polyamic acid (A-4) obtained in Synthesis Example 4 showed that the rubbing resistance was "good", the liquid crystal alignability was "good" and the voltage holding ratio was 98.1% Good "for ion density of 73 pC / cm 2, 1.03 V after 10 minutes of residual DC, 1.06 V after 20 minutes, and 1.14 V after 60 minutes.

&Lt; Example 5 &gt;

Each evaluation and each measurement of the polyamic acid solution containing the polyamic acid (A-5) obtained in Synthesis Example 5 showed that the rubbing resistance was "good", the liquid crystal alignability was "good" and the voltage holding ratio was 99.1% Good "at 2 pC / cm 2 for ion density, 0.38 V after 10 minutes of residual DC, 0.52 V after 20 minutes, and 0.65 V after 60 minutes.

&Lt; Example 6 &gt;

Each evaluation and each measurement of the polyamic acid solution containing the polyamic acid (A-6) obtained in Synthesis Example 6 showed that the rubbing resistance was "good", the liquid crystal alignability was "good" and the voltage retention was 98.1% Good "at 13 pC / cm 2 for ion density, 1.28 V after 10 minutes of residual DC, 1.43 V after 20 minutes, and 1.50 V after 60 minutes.

&Lt; Example 7 &gt;

Each evaluation and each measurement of the polyamic acid solution containing the polyamic acid (A-7) obtained in Synthesis Example 7 showed that the rubbing resistance was "good", the liquid crystal alignability was "good" and the voltage retention was 98.5% Good "at 8 pC / cm 2 for ion density, 0.61 V after 10 minutes, 0.71 V after 20 minutes, and 0.79 V after 60 minutes.

&Lt; Example 8 &gt;

Each evaluation and each measurement of the polyamic acid solution containing the polyamic acid (A-8) obtained in Synthesis Example 8 showed that the rubbing resistance was "good", the liquid crystal alignability was "good", and the voltage holding ratio was 98.7% Good &quot;, and the residual DC was &quot; good &quot; at 1.58 V after 10 minutes, 1.79 V after 20 minutes, and 1.88 V after 60 minutes.

&Lt; Example 9 &gt;

Each evaluation and each measurement of the polyamic acid solution containing the polyamic acid (A-9) obtained in Synthesis Example 9 showed that the rubbing resistance was "good", the liquid crystal alignability was "good" and the voltage retention was 98.8% Good &quot;, and the residual DC was 1.15 V after 10 minutes, 1.39 V after 20 minutes, and 1.51 V after 60 minutes. &Quot; Good &quot;, ion density of 0 pC /

&Lt; Example 10 &gt;

Each evaluation and each measurement of the polyamic acid solution containing the polyamic acid (A-10) obtained in Synthesis Example 10 showed that the rubbing resistance was "good", the liquid crystal alignment property was "good" and the voltage holding ratio was 98.7% Good "at 2 pC / cm 2 for the ion density, 0.19 V after 10 minutes, 0.27 V after 20 minutes, and 0.43 V after 60 minutes.

&Lt; Comparative Example 1 &

Each evaluation and each measurement of the polyamic acid solution containing the polyamic acid (B-1) obtained in Comparative Synthesis Example 1 showed that the rubbing resistance was "good", the liquid crystal alignability was "good", and the voltage holding ratio was 98.4% "Good" for the ion density, "Good" for the ion density of 1 pC / cm 2, residual DC was 1.99 V after 10 minutes, 2.07 V after 20 minutes, and 2.12 V after 60 minutes.

&Lt; Comparative Example 2 &

Each evaluation and each measurement of the polyamic acid solution containing the polyamic acid (B-2) obtained in Comparative Synthesis Example 2 showed that the rubbing resistance was "poor", the liquid crystal alignability was "poor" and the voltage retention was 99.0% "Good" for the ion density, "Good" for the ion density of 0 pC / cm 2, 0.95 V after 10 minutes, 1.21 V after 20 minutes, and 1.42 V after 60 minutes.

&Lt; Comparative Example 3 &

Each evaluation and each measurement of the polyamic acid solution containing the polyamic acid (B-3) obtained in Comparative Synthesis Example 3 showed that the rubbing resistance was "poor", the liquid crystal alignability was "good", and the voltage holding ratio was 98.8% "Good", the ion density was "good" at 3 pC / cm 2, the residual DC was "good" at 0.29 V after 10 minutes, 0.42 V after 20 minutes, and 0.67 V after 60 minutes.

The results are shown in Table 2. As a result, in Examples 1 to 10 using the liquid crystal aligning agent (polyamic acid solution) of the present invention, the liquid crystal alignability was excellent, the rubbing resistance was high, and the ion density was low. In Embodiments 1 to 10, since residual DC in the FFS mode is low, the accumulated charge in the liquid crystal display element is small. In Examples 1 to 10, the voltage holding ratio was also good. The volume resistivity was also high in Examples 2 to 10 using the polyamic acid solutions of Synthesis Examples 2 to 10 as in Example 1 using the polyamic acid solution of Synthesis Example 1.

Industrial availability

By using the liquid crystal aligning agent of the present invention, it is possible to obtain a liquid crystal alignment film having excellent rubbing resistance, good liquid crystal alignability, high voltage holding ratio when the liquid crystal display element is used, and low ion density. The liquid crystal alignment film of the present invention can be used in an FFS mode liquid crystal display device which requires a high display quality because the amount of charge stored in the FFS mode liquid crystal display device is small.

Claims (8)

Reaction of a tetracarboxylic acid dianhydride component containing a tetracarboxylic acid dianhydride having an alicyclic structure or an aliphatic structure with a diamine component containing a diamine having a urea structure and a diamine having a secondary amine at a polymerization reaction site &Lt; / RTI &gt; wherein the liquid crystal aligning agent comprises a polyamic acid obtained by the following method. The method according to claim 1,
A liquid crystal aligning agent characterized by containing at least 50 mol% of a tetracarboxylic acid dianhydride having an alicyclic structure or an aliphatic structure among the tetracarboxylic acid dianhydride components. The method according to claim 1,
Wherein the diamine component contains 10 to 70 mol% of a diamine having a secondary amine at the polymerization reaction site. The method according to claim 1,
A liquid crystal aligning agent characterized by containing, in the diamine component, 10 to 70 mol% of a diamine having a urea structure. The method according to claim 1,
A liquid crystal aligning agent characterized in that the diamine having a secondary amine at the polymerization reaction site is a diamine represented by the following formula (1).
[Chemical Formula 1]

(In the formula (1), X represents an aromatic ring, R ¹ represents an alkylene group of 1 to 5 carbon atoms, and R ² represents an alkyl group of 1 to 4 carbon atoms.) The method according to claim 1,
A liquid crystal aligning agent characterized in that the diamine having a urea structure is a diamine represented by the following formula (2).
(2)

(2), Y represents an oxygen atom or a sulfur atom, R ³ and R ⁴ each independently represent an alkylene group having 1 to 3 carbon atoms, Z ¹ and Z ² each independently represent a single bond, -O-, -S-, -OCO-, or -COO-. A liquid crystal alignment film obtained by using the liquid crystal aligning agent according to any one of claims 1 to 6. A liquid crystal display element comprising the liquid crystal alignment film of claim 7.