CN108885374B

CN108885374B - Liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal display element using same

Info

Publication number: CN108885374B
Application number: CN201780018862.9A
Authority: CN
Inventors: 相马早纪; 森本佳道; 石川和典; 南悟志; 石井秀则
Original assignee: Nissan Chemical Corp
Current assignee: Nissan Chemical Corp
Priority date: 2016-01-22
Filing date: 2017-01-19
Publication date: 2021-09-21
Anticipated expiration: 2037-01-19
Also published as: JPWO2017126627A1; CN108885374A; JP7173194B2; JP6927050B2; JP2021101023A; TWI762464B; TW201736443A; WO2017126627A1; KR20180101576A

Abstract

Providing: a liquid crystal aligning agent, a liquid crystal alignment film and a liquid crystal display element which have excellent voltage holding ratio, rapid relaxation of accumulated charges and are less likely to cause flicker during driving. A liquid crystal aligning agent comprising: a polymer obtained from a diamine having a structure represented by formula (1); and, an organic solvent. (R)₁Represents hydrogen, a fluorine atom, a cyano group, a hydroxyl group or a monovalent organic group, and represents a site bonded to another group. Any hydrogen atom of the phenyl ring is optionally substituted with a monovalent organic group. )

Description

Liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal display element using same

Technical Field

The present invention relates to a liquid crystal aligning agent using a novel polymer, a liquid crystal alignment film, and a liquid crystal display element using the same.

Background

Liquid crystal display elements are widely used as display units of personal computers, mobile phones, smart phones, televisions, and the like. The liquid crystal display element includes, for example: a liquid crystal layer interposed between the element substrate and the color filter substrate, a pixel electrode and a common electrode for applying an electric field to the liquid crystal layer, an alignment film for controlling alignment of liquid crystal molecules in the liquid crystal layer, a Thin Film Transistor (TFT) for converting an electric signal supplied to the pixel electrode, and the like. As a driving method of liquid crystal molecules, a vertical electric field method such as a TN method and a VA method, and a lateral electric field method such as an IPS method and an FFS method are known. It is known that a liquid crystal display element having a wide viewing angle characteristic and capable of displaying high quality can be manufactured by a transverse electric field method in which electrodes are formed only on one side of a substrate and a voltage is applied in a direction parallel to the substrate, as compared with a conventional longitudinal electric field method in which a voltage is applied to electrodes formed on upper and lower substrates to drive liquid crystal.

In the liquid crystal cell of the transverse electric field system, although the viewing angle characteristics are excellent, since the number of electrode portions formed in the substrate is small, if the voltage holding ratio is low, the contrast ratio is lowered by not applying a sufficient voltage to the liquid crystal. Further, if the stability of the liquid crystal alignment is small, the liquid crystal is not returned to the initial state when the liquid crystal is driven for a long time, which causes a decrease in contrast and image sticking, and therefore, the stability of the liquid crystal alignment is important. Further, static electricity is easily accumulated in the liquid crystal cell, and electric charges are also accumulated in the liquid crystal cell by application of positive and negative asymmetric voltages generated by driving, and the accumulated electric charges affect the display in the form of disturbance and afterimage of the liquid crystal alignment, thereby significantly degrading the display quality of the liquid crystal element. Further, immediately after the driving, since the backlight is irradiated to the liquid crystal cell, charges are accumulated, and there are problems that an afterimage is generated even in the driving for a short time, and the magnitude of flicker (flicker) is changed during the driving.

Patent document 1 discloses a liquid crystal aligning agent containing a specific diamine and an aliphatic tetracarboxylic acid derivative as a liquid crystal aligning agent having an excellent voltage holding ratio and reduced charge accumulation when used in such a transverse electric field type liquid crystal display device. However, as the performance of liquid crystal display elements has been improved, the properties required for liquid crystal alignment films have become more severe, and it has been difficult to satisfy all the required properties with these conventional techniques.

Documents of the prior art

Patent document

Patent document 1: international laid-open publication WO2004/021076 pamphlet

Disclosure of Invention

Problems to be solved by the invention

The present invention addresses the problem of providing: a liquid crystal aligning agent, a liquid crystal aligning film and a liquid crystal display element which have excellent voltage holding ratio, fast relaxation of accumulated charges and are not easy to cause flicker during driving.

Means for solving the problems

The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that: the present inventors have also found that various properties can be improved simultaneously by introducing a specific structure into a polymer contained in a liquid crystal aligning agent, and have completed the present invention. The present invention is based on the above findings and the gist thereof is as follows.

1. A liquid crystal aligning agent, comprising: a polymer obtained from a diamine having a structure represented by the following formula (1); and, an organic solvent.

(R₁Represents hydrogen, a fluorine atom, a cyano group, a hydroxyl group or a monovalent organic group, and represents a site bonded to another group. Any hydrogen atom of the phenyl ring is optionally substituted with a monovalent organic group. )

2. The liquid crystal aligning agent according to claim 1, wherein the polymer is at least 1 polymer selected from the group consisting of a polyimide precursor which is a polycondensate of a diamine having a structure represented by the formula (1) and a tetracarboxylic dianhydride, and a polyimide which is an imide compound of the polyimide precursor.

3. The liquid crystal aligning agent according to the above 1 or 2, wherein the diamine is represented by the following formula (2).

(R₁The definition of (2) is the same as that of the above formula (1), R₂Each independently represents a single bond or a structure of the following formula (3), and n represents an integer of 1 to 3. Any hydrogen atom of the phenyl ring is optionally substituted with a 1-valent organic group. )

(R₃Represents a single bond selected from-O-, -COO-, -OCO-, - (CH)₂)_l-、-O(CH₂)_m2-valent organic groups (l and m each represents an integer of 1 to 5) in O-, -CONH-and-NHCO-, (ii)₁Represents a site bonded to a benzene ring in the formula (2)₂Represents a site bonded to an amino group in formula (2). )

4. The liquid crystal aligning agent according to any one of the preceding claims 1 to 3, wherein the polyimide precursor is represented by the following formula (6).

(X₁Is a 4-valent organic radical derived from a tetracarboxylic acid derivative, Y₁Is a 2-valent organic group derived from a diamine containing the structure of the aforementioned formula (1), R₄Is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. )

5. The liquid crystal aligning agent according to the above 4, wherein X in the above formula (6)₁The structure (B) is at least 1 selected from the group consisting of the structures of the formulae (A-1) to (A-21) described later.

6. The liquid crystal aligning agent according to the above 4 or 5, which comprises a polymer having a structural unit represented by the above formula (6) in an amount of 10 mol% or more based on the total polymer contained in the liquid crystal aligning agent.

7. The liquid crystal aligning agent according to any one of claims 4 to 6, wherein the organic solvent contains at least 1 selected from the group consisting of 4-hydroxy-4-methyl-2-pentanone and diethylene glycol diethyl ether.

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

9. A liquid crystal display element comprising the liquid crystal alignment film according to claim 8.

10. The liquid crystal display element according to claim 9, wherein the liquid crystal display element is a lateral electric field driving type.

11. A polymer which is at least 1 selected from the group consisting of a polyimide precursor which is a polycondensate of a diamine having a structure represented by the following formula (1) and a tetracarboxylic dianhydride, and a polyimide which is an imide compound of the polyimide precursor.

(R₁And as described in 1 above. )

12. The polymer according to claim 11, wherein the diamine is represented by the following formula (2).

(R₁、R₂And n is as described in the above 3. )

13. The polymer according to claim 11 or 12, wherein the polyimide precursor is represented by formula (6) below.

(X₁、Y₁And R₄As described in the above 4. )

14. The polymer according to the above 13, wherein, in the above formula (6), X₁The structure (B) is at least 1 selected from the group consisting of the structures of the formulae (A-1) to (A-21) described later.

ADVANTAGEOUS EFFECTS OF INVENTION

By using the liquid crystal aligning agent of the present invention, a liquid crystal alignment film which can quickly relax accumulated charges and is less likely to cause flicker (flicker) during driving, and a liquid crystal display element having excellent display characteristics can be provided. The reason why the above-mentioned problems can be solved by the invention of the present application is not clear, but is considered as follows.

The structure of the above (1) contained in the polymer contained in the liquid crystal aligning agent of the present invention has a conductive pyrrole structure and a conjugated structure, and thus, for example, in a liquid crystal alignment film, the movement of charges can be promoted and the relaxation of accumulated charges can be promoted.

Detailed Description

< amine having specific Structure >

The liquid crystal aligning agent of the present invention contains: a polymer (also referred to as a specific polymer in the present invention) obtained from a diamine (also referred to as a specific diamine in the present invention) having a structure represented by the following formula (1); and, an organic solvent.

In the above formula (1), R₁Represents hydrogen, a fluorine atom, a cyano group, a hydroxyl group or a monovalent organic group, and represents a site bonded to another group. The hydrogen atom of the benzene ring is optionally substituted with a monovalent organic group.

Examples of the monovalent organic group herein include an alkyl group, an alkenyl group, an alkoxy group, a fluoroalkyl group, a fluoroalkenyl group, or a fluoroalkoxy group having 1 to 10, preferably 1 to 3 carbon atoms. Wherein R is₁Preferably a hydrogen atom, or a methyl group.

In the structure of the above formula (1), the bonding position of the benzene ring to the pyrrole ring is preferably a carbon atom adjacent to the nitrogen atom on the pyrrole ring as shown in the following formula (1-1) from the viewpoint of charge transfer.

The specific diamine can be represented by, for example, the following formula (1-2), particularly preferably a diamine represented by the following formula (1-3), and still more preferably a diamine represented by the following formula (1-4).

In the formulae (1-2) to (1-4), R₁Is as defined in the above formula (1), Q₁、Q₂Each independently is a single bond or a 2-valent organic group, i.e., may be Q₁And Q₂Different structures from each other. In addition, 2 Qs in the formula (1-4)₂May be different structures from each other. Further, any hydrogen atom of the benzene ring may be substituted with a monovalent organic group as in the case of the above formula (1).

Preferable examples of the specific diamine include diamines represented by the following formula (2), and diamines represented by the following formula (2-1) are more preferable.

R in the above formula (2) and formula (2-1)₁The definition of (A) is the same as that of the above formula (1). 2R₂Each independently represents a single bond or a structure of the following formula (3). In the same manner as in the case of the above formula (1), any hydrogen atom of the benzene ring is optionally substituted by a monovalent organic group.

In the above formula (3), R₃Represents a single bond selected from the group consisting of-O-, -COO-, -OCO-, - (CH)₂)_l-、-O(CH₂)_mAnd a 2-valent organic group selected from the group consisting of O-, -CONH-, and-NHCO-, wherein l and m represent an integer of 1 to 5. Wherein R is a component for reducing the accumulated charge₃Preferably a single bond, -O-, -COO-, -OCO-, -CONH-or-NHCO-. In addition, al₁Represents a site bonded to the benzene ring in the formula (2)₂Represents a site bonded to an amino group in formula (2).

N in the above formula (2) and formula (2-1) represents an integer of 1 to 3. Preferably 1 or 2.

Specific examples of the diamine of the formula (2) include the following, but are not limited thereto. Among them, (2-1-1), (2-1-2), (2-1-3), (2-1-5), (2-1-8), (2-1-9), (2-1-10), (2-1-11) or (2-1-12) is preferable, and (2-1-1), (2-1-2), (2-1-3), (2-1-11) or (2-1-12) is particularly preferable, from the viewpoint of relaxation of accumulated charge.

< Synthesis method of specific diamine >

The method for synthesizing the above-mentioned specific diamine is not particularly limited. For example, the following methods may be mentioned: a dinitro compound represented by the following formula (4) is used, and the nitro group contained therein is converted to an amino group by a reduction reaction.

In the formula (4), R₁Is as defined in the above formula (1)

The catalyst used in the reduction reaction is preferably an activated carbon-supported metal which is commercially available, and examples thereof include palladium-activated carbon, platinum-activated carbon, rhodium-activated carbon, and the like. Further, a metal catalyst which is not necessarily an activated carbon-supported type, such as palladium hydroxide, platinum oxide, and raney nickel, may be used. Generally, palladium-activated carbon, which is widely used, is preferable because good results can be obtained.

In order to more efficiently perform the reduction reaction, the reaction may be performed in the presence of activated carbon. In this case, the amount of the activated carbon to be used is not particularly limited, but is preferably 1 to 30% by mass, more preferably 10 to 20% by mass, based on the dinitro compound (4). For the same reason, the reaction may be carried out under pressure. In the above case, the reduction of the benzene nucleus is carried out in a pressurized range of up to 20 atmospheres. The reaction is preferably carried out in the range of up to 10 atmospheres.

The solvent may be used without limitation as long as it does not react with each raw material. For example, it is possible to use: aprotic polar organic solvents (dimethylformamide, dimethylsulfoxide, dimethylacetamide, N-methyl-2-pyrrolidone, and the like); ethers (diethyl ether, diisopropyl ether, tert-butyl methyl ether, cyclopentyl methyl ether, tetrahydrofuran, dioxane, etc.); aliphatic hydrocarbons (pentane, hexane, heptane, petroleum ether, etc.); aromatic hydrocarbons (benzene, toluene, xylene, mesitylene, chlorobenzene, dichlorobenzene, nitrobenzene, tetralin, etc.); halogen-based hydrocarbons (chloroform, dichloromethane, carbon tetrachloride, dichloroethane, etc.); lower fatty acid esters (methyl acetate, ethyl acetate, butyl acetate, methyl propionate, etc.); nitriles (acetonitrile, propionitrile, butyronitrile, etc.) and the like. These solvents may be used in 1 kind, or in 2 or more kinds. Further, the solvent may be dried by using a suitable dehydrating agent or drying agent and used as a nonaqueous solvent.

The amount of the solvent (reaction concentration) is not particularly limited, and is 0.1 to 100 times by mass relative to the dinitro compound (4). Preferably 0.5 to 30 times by mass, and more preferably 1 to 10 times by mass.

The reaction temperature is not particularly limited, but is preferably in the range of-100 ℃ to the boiling point of the solvent used, and more preferably-50 to 150 ℃. The reaction time is usually 0.05 to 350 hours, preferably 0.5 to 100 hours.

[ production method of Compound of formula (4) ]

The method for synthesizing the compound of formula (4) is not particularly limited, and examples thereof include the following methods: synthesizing a dinitro group represented by the following formula (5), and introducing a protecting group R into the NH group₁。

Introduction of R₁In this case, the compound may be a compound capable of reacting with an amine. For example, canExamples thereof include acid halides, acid anhydrides, isocyanates, epoxides, oxetanes, haloaromatics and haloalkanes. In addition, alcohols in which the hydroxyl group of the alcohol is substituted with a leaving group such as OMs (methylsulfonyl), OTf (trifluoromethylsulfonyl), and OTs (tosyl) may be used.

By reaction with acyl halides to introduce R₁In the case of (3), it is preferably carried out in the presence of a base. Examples of the acid halide include acetyl chloride, propionyl chloride, methyl chloroformate, ethyl chloroformate, n-propyl chloroformate, isopropyl chloroformate, n-butyl chloroformate, isobutyl chloroformate, tert-butyl chloroformate, benzyl chloroformate, and 9-fluorene chloroformate. The base is not particularly limited as long as it can be synthesized, and inorganic bases such as potassium carbonate, sodium carbonate, cesium carbonate, sodium alkoxide, potassium alkoxide, sodium hydroxide, potassium hydroxide, and sodium hydride, and organic bases such as pyridine, dimethylaminopyridine, trimethylamine, triethylamine, and tributylamine can be used. The reaction solvent and the reaction temperature are the same as those in the reduction reaction of the nitro compound (4).

By reaction with anhydrides to introduce R₁In the case of (3), examples of the acid anhydride include acetic anhydride, propionic anhydride, dimethyl dicarbonate, diethyl dicarbonate, di-t-butyl dicarbonate, dibenzyl dicarbonate, and the like. As the catalyst for promoting the reaction, pyridine, collidine, N-dimethyl-4-aminopyridine, and the like can be used. The amount of the catalyst is 0.0001 to 1 mol relative to the compound (5). The reaction solvent and the reaction temperature are the same as those in the above acid halide.

By reaction with isocyanates to introduce R₁In the case of (2), examples of the isocyanate include methyl isocyanate, ethyl isocyanate, n-propyl isocyanate, and phenyl isocyanate. The reaction solvent and the reaction temperature are the same as in the above acid halide.

By reaction with epoxy compounds or oxetane compounds to introduce R₁In the case of (2), examples of the epoxy compounds and oxetanes include ethylene oxide, propylene oxide, 1, 2-butylene oxide, and oxetane. The reaction solvent and the reaction temperature are the same as those in the above acid halide.

R is introduced by reacting an alcohol having a hydroxyl group of the alcohol substituted with a leaving group such as OMs, OTf, OTs or the like₁In the case of (3), it is preferably carried out in the presence of a base. Examples of the alcohol include methanol, ethanol, and 1-propanol, and these alcohols are reacted with methanesulfonyl chloride, trifluoromethanesulfonyl chloride, and p-toluenesulfonyl chloride to obtain an alcohol substituted with a leaving group such as OMs, OTf, and OTs. Examples of the base, the reaction solvent and the reaction temperature are the same as those in the above-mentioned acid halide.

By reaction of alkyl halides to introduce R₁In the case of (3), it is preferably carried out in the presence of a base. Examples of the alkyl halide include methyl iodide, ethyl iodide, n-propyl iodide, methyl bromide, ethyl bromide, and n-propyl bromide. As examples of the base, metal alkoxides such as potassium tert-butoxide and sodium tert-butoxide can be used in addition to the above-mentioned base. The reaction solvent and the reaction temperature are the same as in the above acid halide.

[ production method of Compound of formula (5) ]

The method for synthesizing the compound of formula (5) is not particularly limited, and when the substitution positions on the pyrrole ring of formula (5) are 2-position and 4-position, for example, as shown in the following reaction formula 1, the compound can be obtained by reacting an α -haloketone having a nitro group with a ketone having a nitro group, preferably in the presence of a base. In the reaction formula 1, X represents Br, I or OTf.

As the base used in the above reaction, the base exemplified in the above acid halide can be used, and the reaction solvent and the reaction temperature are the same as those described above.

In order to accelerate the rate in the above reaction, zinc chloride, sodium iodide, potassium iodide, tetrabutylammonium iodide, or the like can be used.

On the other hand, when the substitution in the pyrrole ring of the compound of formula (5) is other than the 2-position and the 4-position, the corresponding halopyrrole and the organometallic reagent are subjected to a cross-coupling reaction preferably using a metal catalyst, and thus the compound can be obtained.

In the reaction formula 2, X represents Br, I or OTf. M represents B (OH)₂Or 4,4,5, 5-tetramethyl-1, 3, 2-dioxaborolan-2-yl.

The above cross-coupling reaction (suzuki-miyaura reaction) preferably uses a metal complex and a ligand as a catalyst, but the reaction proceeds even in the absence of a catalyst. Examples of the metal complex include palladium acetate, palladium chloride-acetonitrile complex, palladium-activated carbon, bis (dibenzylideneacetone) palladium, tris (dibenzylideneacetone) dipalladium, bis (acetonitrile) dichloropalladium, bis (benzonitrile) dichloropalladium, CuCl, CuBr, CuI, CuCN and the like. Examples of the ligand include triphenylphosphine, tri-o-tolylphosphine, diphenylmethylphosphine, phenyldimethylphosphine, 1, 2-bis (diphenylphosphino) ethane, 1, 3-bis (diphenylphosphino) propane, 1, 4-bis (diphenylphosphino) butane, 1' -bis (diphenylphosphino) ferrocene, trimethyl phosphite, triethyl phosphite, triphenyl phosphite, tri-t-butylphosphine, and the like.

The amount of the metal complex to be used may be a so-called catalyst amount, and is preferably 20 mol% or less, more preferably 10 mol% or less, based on the substrate.

< Polymer >

The liquid crystal aligning agent of the present invention is a polymer obtained by using a specific diamine. Specific examples of the polymer include polyamic acids, polyamic acid esters, polyimides, polyureas, and polyamides. Among these, at least 1 type of polymer selected from the group consisting of a polyimide precursor having a structural unit represented by the following formula (6) and a polyimide which is an imide compound of the polyimide precursor is preferable.

In the above formula (6), X₁Is a 4-valent organic group derived from a tetracarboxylic acid derivative. Y is₁Is a 2-valent organic group derived from a diamine comprising the structure of formula (1). R₄Is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. From the viewpoint of easiness of imidation by heating, R₄Preferably a hydrogen atom, a methyl group or an ethyl group.

In the above formula (6), X₁Is a 4-valent organic group derived from a tetracarboxylic acid derivative. X₁The number of the polymers may be 1 or 2 or more, and the number is appropriately selected depending on the degree of the desired properties such as solubility in a solvent, coatability of a liquid crystal aligning agent, alignment of liquid crystal when forming a liquid crystal alignment film, voltage holding ratio, and accumulated charge.

As X₁Specific examples of (4) include the structures of formulae (X-1) to (X-46) described in International patent publication No. 2015/119168 on pages 13 to 14.

X is shown below as preferred₁The following (A-1) to (A-21) are provided.

Among the above-mentioned structures, (A-1) or (A-2) is particularly preferable from the viewpoint of further improvement of the brushing resistance, (A-4) is particularly preferable from the viewpoint of further improvement of the relaxation rate of the accumulated charge, and (A-15) to (A-17) are particularly preferable from the viewpoint of further improvement of the liquid crystal alignment property and the relaxation rate of the accumulated charge.

In the formula (6), Y₁There may be mentioned a structure obtained by excluding 2 amino groups from the diamine of the formula (2). Wherein, Y₁More preferred are structures obtained by excluding 2 amino groups from the structures of the above formulae (2-1-1), (2-1-2), (2-1-3), (2-1-5), (2-1-8), (2-1-9), (2-1-10), (2-1-11) and (2-1-12), and particularly preferred are structures obtained by excluding 2 amino groups from the structures of (2-1-1), (2-1-2), (2-1-3), (2-1-11) and (2-1-12).

< other Polymer (building Block) >)

The liquid crystal aligning agent of the present invention may contain, in addition to the polyimide precursor having the structural unit of the above formula (6): at least 1 polymer selected from the group consisting of a polyimide precursor having a structural unit represented by the following formula (7) and a polyimide which is an imide compound of the polyimide precursor.

In the formula (7), X₂Is a 4-valent organic group derived from a tetracarboxylic acid derivative. Y is₂Is a 2-valent organic group derived from a diamine not having the structure of formula (1). R₄The same as defined in the aforementioned formula (6). R₅Represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. In addition, 2R are preferred₅At least one of them is a hydrogen atom.

As X₂The specific examples of (3) include preferred examples, and X of the formula (6)₁The same as in example (1). In addition, Y₂The number of the polymers is selected depending on the solubility of the polymers in a solvent, the coating property of a liquid crystal aligning agent, the alignment property of liquid crystal when forming a liquid crystal alignment film, the voltage holding ratio, the accumulated charge, and other characteristics, and may be 1 or 2 or more.

If Y is shown₂Specific examples of (4) include the structure of formula (2) described on page 4 of International patent publication No. 2015/119168, and the structures of formulae (Y-1) to (Y-97) and (Y-101) to (Y-118) described on pages 8 to 12; a divalent organic group obtained by removing 2 amino groups from formula (2) described in page 6 of international publication No. 2013/008906; a divalent organic group obtained by removing 2 amino groups from formula (1) described on page 8 of international publication No. 2015/122413; a structure of formula (3) described on page 8 of International publication No. 2015/060360; a divalent organic group obtained by removing 2 amino groups from the formula (1) described in Japanese laid-open patent publication No. 2012-173514 on page 8; a divalent organic group obtained by removing 2 amino groups from the formulae (A) to (F) described in International publication No. 2010-050523 on page 9, and the like.

Preferred Y is shown below₂Structure of (2), however, the present inventionThe invention is not limited to these.

Among the above, from the viewpoint of further improving the rubbing resistance, (B-28), (B-29) and the like are particularly preferable, from the viewpoint of further improving the liquid crystal alignment properties, (B-1) to (B-3) and the like are particularly preferable, from the viewpoint of further improving the relaxation rate of the accumulated charge, (B-14) to (B-18), (B-27) and the like are particularly preferable, and from the viewpoint of further improving the voltage holding ratio, (B-26) and the like are preferable.

When the liquid crystal aligning agent of the present invention contains a polyimide precursor having a structural unit of formula (6) and a polyimide precursor having a structural unit of formula (7), the structural unit of formula (6) is preferably 10 mol% or more, more preferably 20 mol% or more, and particularly preferably 30 mol% or more with respect to the total of formula (6) and formula (7).

The molecular weight of the polyimide precursor of the above formula (6) and formula (7) is preferably 2000 to 500000, more preferably 5000 to 300000, and further preferably 10000 to 100000 in terms of weight average molecular weight.

Examples of the polyimide having a divalent group represented by the formula (1) in the main chain include polyimides obtained by ring-closing the polyimide precursor. In this polyimide, the ring-closure ratio of the amic acid group (also referred to as imidization ratio) is not necessarily 100%, and can be arbitrarily adjusted depending on the application and purpose.

Examples of the method for imidizing the polyimide precursor include: thermal imidization in which a solution of a polyimide precursor is directly heated; or, a catalyst is added to a solution of a polyimide precursor to catalyze imidization.

< liquid Crystal Aligning agent >

The liquid crystal aligning agent of the present invention contains a polymer (specific polymer) obtained from a diamine having a structure represented by formula (1), and may contain 2 or more kinds of specific polymers having different structures. In addition to the specific polymer, another polymer, that is, a polymer not having the divalent group represented by the formula (1) may be contained. Examples of the other polymer include polyamic acids, polyimides, polyamic acid esters, polyesters, polyamides, polyureas, polyorganosiloxanes, cellulose derivatives, polyacetals, polystyrenes or derivatives thereof, poly (styrene-phenylmaleimide) derivatives, poly (meth) acrylates, and the like. When the liquid crystal aligning agent of the present invention contains another polymer, the ratio of the specific polymer to the total polymer components is preferably 5% by mass or more, and for example, 5 to 95% by mass.

The liquid crystal aligning agent is generally in the form of a coating liquid in order to form a uniform thin film. The liquid crystal aligning agent of the present invention is also preferably a coating solution containing the polymer component and an organic solvent for dissolving the polymer component. In this case, the concentration of the polymer in the liquid crystal aligning agent can be appropriately changed by setting the thickness of the coating film to be formed. The content is preferably 1% by mass or more in view of the desire to form a uniform and defect-free coating film, and is preferably 10% by mass or less in view of the storage stability of the solution. The concentration of the polymer is particularly preferably 2 to 8 mass%.

The organic solvent contained in the liquid crystal aligning agent is not particularly limited as long as it is a solvent that uniformly dissolves the polymer component. Specific examples thereof include N, N-dimethylformamide, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ -butyrolactone, 1, 3-dimethyl-imidazolidinone, methyl ethyl ketone, cyclohexanone, and cyclopentanone. Among them, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or γ -butyrolactone is preferably used.

The organic solvent contained in the liquid crystal aligning agent of the present invention may be used in combination with the above-mentioned solvent to improve coatability and surface smoothness of a coating film when the liquid crystal aligning agent is coated. Specific examples of the organic solvent are described below, but the organic solvent is not limited thereto.

Examples thereof include ethanol, isopropanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, isopentanol, tert-pentanol, 3-methyl-2-butanol, neopentyl alcohol, 1-hexanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-octanol, 2-ethyl-1-hexanol, cyclohexanol, 1-methylcyclohexanol, 2-methylcyclohexanol, 3-methylcyclohexanol, 1, 2-ethanediol, 1, 2-propanediol, isobutanol, 2-butanol, 2-pentanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-ethyl-1-pentanol, 2-hexanol, 3-methyl-cyclohexanol, 1, 2-ethanediol, 1, 2-propanediol, 2-butanol, and mixtures thereof, 1, 3-propanediol, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, 2, 3-butanediol, 1, 5-pentanediol, 2-methyl-2, 4-pentanediol, 2-ethyl-1, 3-hexanediol, dipropyl ether, dibutyl ether, dihexyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1, 2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 2-pentanone, 3-pentanone, 2-hexanone, 2-heptanone, 4-heptanone, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 1, 4-butanediol, 2, 3-butanediol, 1, 5-pentanediol, 2-diethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethyl ether, diethylene glycol dimethyl ether, 2-pentanone, 2-hexanone, 2-heptanone, 4-heptanone, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 1-methyl-pentyl acetate, 2-butanediol, 2-butyl acetate, 2-butyl acetate, and/or 2-butyl acetate, 2-butyl, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, 2- (methoxymethoxy) ethanol, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, 2- (hexyloxy) ethanol, furfuryl alcohol, diethylene glycol, propylene glycol monobutyl ether, 1- (butoxyethoxy) propanol, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monoacetate, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2- (2-ethoxyethoxy) ethyl acetate, ethylene glycol mono-butyl ether acetate, propylene glycol mono-butyl ether acetate, propylene glycol mono-butyl ether acetate, propylene glycol mono-butyl ether acetate, propylene glycol mono-butyl ether mono-ether acetate, propylene glycol mono-ether mono-butyl ether mono-butyl ether acetate, propylene glycol mono-butyl ether mono-2- (2-butyl ether mono-butyl ether mono-butyl ether-butyl ether-2-butyl ether mono-butyl ether-butyl ether-2- (2-butyl ether-2-ethyl acetate, propylene glycol mono-2-ethyl ether-2-ethyl ether-, Diethylene glycol acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, methyl ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-ethoxypropionic acid, 3-methoxypropionic acid, propyl 3-methoxypropionate, butyl 3-methoxypropionate, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, and solvents represented by the following formulae [ D-1] to [ D-3 ].

Formula [ D-1]In (D)¹Represents an alkyl group having 1 to 3 carbon atoms of the formula [ D-2 ]]In (D)²Represents an alkyl group having 1 to 3 carbon atoms, formula [ D-3]]In (D)³Represents an alkyl group having 1 to 4 carbon atoms.

Among them, 1-hexanol, cyclohexanol, 1, 2-ethylene glycol, 1, 2-propylene glycol, propylene glycol monobutyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monobutyl ether, or dipropylene glycol dimethyl ether is preferably used. The kind and content of such a solvent are appropriately selected depending on the coating apparatus, coating conditions, coating environment, and the like of the liquid crystal aligning agent.

The liquid crystal aligning agent of the present invention may further contain components other than the polymer component and the organic solvent. Examples of such additional components include an adhesion promoter for improving adhesion between the liquid crystal alignment film and the substrate and adhesion between the liquid crystal alignment film and the sealing material, a crosslinking agent for improving strength of the liquid crystal alignment film, a dielectric for adjusting dielectric constant and resistance of the liquid crystal alignment film, and a conductive material. Specific examples of such additional components include those disclosed in paragraph 0105 to 0116 on page 53 of international publication No. 015/060357.

< liquid Crystal alignment film >

The liquid crystal alignment film of the present invention is obtained from the liquid crystal aligning agent. Examples of the method for obtaining the liquid crystal alignment film include the following methods: the liquid crystal aligning agent in the form of a coating liquid is applied to a substrate, dried, and fired, and the obtained film is subjected to an alignment treatment by a brushing treatment method or a photo-alignment treatment method.

The substrate to which the liquid crystal aligning agent is applied is not particularly limited as long as it is a substrate having high transparency, and a plastic substrate such as an acryl substrate or a polycarbonate substrate may be used together with a glass substrate or a silicon nitride substrate. In this case, if a substrate on which an ITO electrode or the like for driving a liquid crystal is formed is used, it is preferable in terms of simplification of the process. In the case of a reflective liquid crystal display element, an opaque material such as a silicon wafer may be used as a single-sided substrate, and a material that reflects light such as aluminum may be used as an electrode in this case.

The method of applying the liquid crystal aligning agent is not particularly limited, and the method is generally industrially screen printing, offset printing, flexographic printing, ink jet printing, or the like. Other coating methods include a dipping method, a roll coating method, a slit coating method, a spin coating method, a spray coating method, and the like, and they can be used according to the purpose.

After the liquid crystal aligning agent is coated on the substrate, the solvent may be evaporated and fired by a heating means such as a hot plate, a thermal cycle oven, or an IR (infrared ray) oven. The drying and firing steps after the application of the liquid crystal aligning agent of the present invention can be carried out at any temperature and for any time. In general, in order to sufficiently remove the solvent contained, there are listed: firing at 50-120 ℃ for 1-10 minutes, and then firing at 150-300 ℃ for 5-120 minutes.

When the thickness of the liquid crystal alignment film after firing is too small, the reliability of the liquid crystal display device may be lowered, and therefore, the thickness is preferably 5 to 300nm, more preferably 10 to 200 nm.

The liquid crystal alignment film of the present invention is suitable for a liquid crystal display element of a transverse electric field system such as an IPS system or an FFS system, and is particularly useful as a liquid crystal alignment film for a liquid crystal display element of an FFS system.

< liquid crystal display element >

The liquid crystal display element of the present invention can be obtained by obtaining a substrate with a liquid crystal alignment film obtained from the liquid crystal alignment agent, then fabricating a liquid crystal cell by a known method, and using the liquid crystal cell.

As an example of a method for manufacturing a liquid crystal cell, a liquid crystal display element having a passive matrix structure will be described. Note that each pixel portion constituting an image display may be an element having an active matrix structure in which a conversion element such as a TFT (thin film Transistor) is provided.

Specifically, a transparent glass substrate is prepared, a common electrode is provided on one substrate, and a segment electrode (segment electrode) is provided on the other substrate. These electrodes may be made, for example, as ITO electrodes, patterned so as to enable a desired image representation. Next, an insulating film is provided on each substrate to cover the common electrode and the segment electrode. The insulating film may be made of SiO formed by a sol-gel method, for example₂-TiO₂And (3) a film of the composition. Next, a liquid crystal alignment film was formed on each substrate under the above conditions.

Next, for example, an ultraviolet-curable sealing material is disposed at a predetermined position on one of the 2 substrates on which the liquid crystal alignment film is formed, and after liquid crystal is disposed at a plurality of predetermined positions on the liquid crystal alignment film surface, the other substrate is bonded and pressure-bonded so that the liquid crystal alignment film faces each other, thereby spreading the liquid crystal on the front surface of the liquid crystal alignment film, and then the sealing material is cured by irradiating ultraviolet rays on the entire surface of the substrate, thereby obtaining a liquid crystal cell.

Alternatively, after a liquid crystal alignment film is formed on a substrate, when a sealing material is disposed at a predetermined position on one substrate, an opening capable of being filled with liquid crystal from the outside is provided, and after the substrates are bonded, a liquid crystal material is injected into a liquid crystal cell through the opening provided in the sealing material, and then the opening is sealed with an adhesive to obtain a liquid crystal cell. The liquid crystal material may be injected by a vacuum injection method or a method using a capillary phenomenon in the atmosphere.

In any of the above methods, in order to secure a space for filling the liquid crystal cell with the liquid crystal material, it is preferable to provide columnar protrusions on one substrate, to spread spacers on one substrate, to mix spacers in a sealing material, or to combine them.

The liquid crystal material includes nematic liquid crystal and smectic liquid crystal, and among them, nematic liquid crystal is preferable, and either of positive liquid crystal material and negative liquid crystal material can be used. Subsequently, a polarizing plate was disposed. Specifically, a pair of polarizing plates is preferably attached to the surfaces of the 2 substrates opposite to the liquid crystal layer.

The liquid crystal alignment film and the liquid crystal display element of the present invention are not limited to the above description as long as the liquid crystal alignment agent of the present invention is used, and may be produced by other known methods. The steps until obtaining a liquid crystal display element from a liquid crystal aligning agent are disclosed in, for example, paragraph 0081 on page 17, paragraph 0074 to page 19 of Japanese patent laid-open publication No. 2015-135393.

Examples

The present invention will be specifically described below with reference to examples and the like. The present invention is not limited to these examples. The methods for short-circuiting and evaluating the properties of the compounds used below are as follows.

In the above formula, Boc is a group represented by the following formula.

< organic solvent >

NMP: n-methyl-2-pyrrolidone, GBL: gamma-butyrolactone,

BCS: butyl cellosolve

< additive >

LS-4668: 3-glycidoxypropyltriethoxysilane

< crosslinking agent >

(¹Measurement of H-NMR)

The device comprises the following steps: varian NMR system 400NB (400MHz, manufactured by Varian corporation), and JMTC-500/54/SS (500MHz, manufactured by JEOL corporation)

And (3) determination of a solvent: CDCl₃(deuterated chloroform), DMSO-d₆(deuterated dimethyl sulfoxide)

Reference substance: TMS (tetramethylsilane) (δ: 0.0ppm,¹H) and CDCl₃(δ：77.0ppm，¹³C)

< determination of molecular weight of polyimide precursor and polyimide >

The measurement was carried out by using a Gel Permeation Chromatography (GPC) apparatus (GPC-101) (manufactured by Showa Denko K.K.) and a column (KD-803, KD-805) (manufactured by Shodex Co., Ltd.) in the following manner.

Column temperature: 50 deg.C

Eluent: n, N' -dimethylformamide (as additive, lithium bromide monohydrate (LiBr. H2O) 30mmol/L (liter), phosphoric acid anhydrous crystal (orthophosphoric acid) 30mmol/L, Tetrahydrofuran (THF) 10ml/L)

Flow rate: 1.0 ml/min

Standard sample for standard curve preparation: TSK standard polyethylene oxides (molecular weight; approx. 900000, 150000, 100000 and 30000, manufactured by Tosoh Corp.) and polyethylene glycols (molecular weight; approx. 12000, 4000 and 1000, manufactured by Polymer Laboratories Ltd.).

< measurement of viscosity >

The viscosity of the polyamic acid solution was measured using an E-type viscometer TVE-22H (manufactured by Toyobo industries Co., Ltd.) at a temperature of 25 ℃ with a sample volume of 1.1mL and a cone rotor TE-1(1 ℃ 34', R24)

< Synthesis of diamine Compound (DA-1) >

Zinc chloride (120.3g, 882mmol) was added to a 3L (liter) four-necked flask, the temperature was raised to 100 ℃ and vacuum-dried for 1 hour by means of an oil pump. Then, toluene (460g), diethylamine (45.0g, 615mmol), t-butanol (46.4g, 626mmol), 2-bromo-4-nitroacetophenone (100.0g, 410mmol) and 4-nitroacetophenone (104.2g, 631mmol) were added in this order under a nitrogen atmosphere at room temperature, and the mixture was stirred at room temperature for 3 days. After completion of the reaction was confirmed by HPLC (high performance liquid chromatography), a 5% aqueous solution (400g) of sulfuric acid was added for neutralization, and the mixture was stirred at room temperature for 1 hour. The precipitated crystals were filtered under reduced pressure, washed with toluene (200g), pure water (300g) and methanol (200g), and dried to obtain crude crystals. After the obtained crude crystals were completely dissolved in tetrahydrofuran (1340g) at 60 ℃, ethanol (1340g) was added and stirred at 5 ℃ for 1 hour. The precipitated crystals were filtered under reduced pressure, washed with ethanol (200g), and dried to obtain powdery crystals of the compound (1) (yield 63g, yield 45%).

1H-NMR(DMSO-d₆)：8.40-8.36(4H，m)，8.28-8.24(4H，m)，3.53(4H，s)

Compound (1) (65.8g, 200mmol), ammonium acetate (84.5g,1100mmol) and acetic acid (855g) were charged into a 2L four-necked flask, and the mixture was stirred at reflux for 3 hours while warming to 120 ℃. After completion of the reaction was confirmed by HPLC (high performance liquid chromatography), the reaction mixture was added to cold water (4000g) and stirred for 1 hour. The precipitated crystals were filtered under reduced pressure, washed with acetonitrile (100g) to obtain a repulped product, and dried to obtain powdery crystals of the compound (2) (yield 53g, yield 78%).

1H-NMR(DMSO-d₆)：11.8(1H，br)，8.30-8.26(4H，m)，8.11-8.07(4H，m)，7.04(2H，s)

A mixture of powdery crystals (22g, 72.4mmol) of the compound (2), 5 mass% palladium on carbon (Pd/C) (50% aqueous form), Egret's charcoal (2.0g) and dioxane (220g) was stirred under hydrogen pressure at 80 ℃ for 8 hours. After completion of the reaction, the catalyst was filtered, concentrated, and 2-propanol (300g) was added thereto and stirred at 5 ℃ for 1 hour. The precipitated crystals were filtered under reduced pressure, washed with methanol (50g), and dried to obtain DA-1 as powdery crystals (yield 13g, yield 69%).

1H-NMR(DMSO-d₆)：10.6(1H，s)，7.39-7.35(4H，m)，6.57-6.53(4H，m)，6.19(2H，s)，5.01(4H，s)

[ Synthesis example 1]

DA-1(2.49g, 10.0mmol) was charged into a 100ml four-necked flask equipped with a stirrer and a nitrogen inlet, then 29.0g of NMP29 was added thereto, and the mixture was dissolved by stirring while feeding nitrogen. While the solution was stirred, CA-2(0.98g, 5.0mmol) and NMP3.6g (addition amount 1 in Table 1) were added, followed by stirring at 25 ℃ for 1 hour. Thereafter, CA-1(0.87g, 4.0mmol) and NMP3.6g (addition amount 2 in Table 1) were added, followed by stirring at 50 ℃ for 12 hours to obtain a polyamic acid solution (PAA-A1) having a resin solid content of 12 mass%. The viscosity of the polyamic acid solution was 300 mPas.

[ Synthesis examples 2 to 16]

Polyamic acid solutions (PAA-a2) to (PAA-a9) and (PAA-B1) to (PAA-B7) having the solid content concentrations and viscosities shown in table 1 were obtained in the same manner as in synthesis example 1, except that the reaction temperatures shown in table 1 were respectively set using the tetracarboxylic dianhydride component, the diamine component, and the NMP shown in table 1.

[ Table 1]

[ Synthesis example 17]

DA-6(4.03g, 16.5mmol), DA-7(3.59g, 9.0mmol) and DA-8(2.50g, 4.5mmol) were charged into a 200ml four-necked flask equipped with a stirrer and a nitrogen inlet, 102.1g of NMP was added thereto, and the mixture was dissolved by stirring while feeding nitrogen. While the solution was stirred, CA-4(4.37g, 19.5mmol) and NMP (12.8 g) were added thereto, and the mixture was stirred at 40 ℃ for 3 hours. Thereafter, CA-2(1.71g, 8.7mmol) and NMP (12.8 g) were added thereto at 25 ℃ and the mixture was further stirred for 12 hours to obtain a polyamic acid solution having a resin solid content of 15 mass%. The viscosity of the polyamic acid solution was 820 mPas.

80.0g of the polyamic acid solution was separated and recovered, and after 70.0g of NMP was added, 6.8g of acetic anhydride and 1.8g of pyridine were added to the solution to react at 50 ℃ for 3 hours. The reaction solution was poured into 555.0g of methanol, and the resulting precipitate was filtered off. The precipitate was washed with methanol and dried under reduced pressure at 60 ℃ to obtain polyimide powder. The imidization rate of this polyimide was 75%. To 80.0g of the obtained polyimide powder, NMP586.7g was added, and the mixture was stirred at 50 ℃ for 20 hours to dissolve it, thereby obtaining a polyimide solution (SPI-B8).

[ Synthesis example 18]

DA-6(2.20g, 9.0mmol), DA-13(1.62g, 15.0mmol) and DA-14(2.45g, 6.0mmol) were charged into a 100ml four-necked flask equipped with a stirrer and a nitrogen inlet, and then 81.8g of NMP was added thereto, and the mixture was dissolved by stirring while feeding nitrogen. While stirring the solution, CA-4(6.52g, 29.10mmol) and NMP (9.1 g) were added, followed by stirring at 40 ℃ for 24 hours to obtain a polyamic acid solution (PAA-B9) having a resin solid content of 12 mass%. The viscosity of the polyamic acid solution was 386 mPas.

[ Synthesis example 19]

DA-1(2.62g, 10.5mmol), DA-2(1.39g, 7.0mmol) and DA-3(3.49g, 17.5mmol) were charged into a 200ml four-necked flask equipped with a stirrer and a nitrogen inlet, and then 70.0g of NMP was added thereto, and the mixture was dissolved by stirring while feeding nitrogen. While the solution was stirred, CA-2(1.70g, 8.7mmol) and NMP 9.5g were added, followed by stirring at 25 ℃ for 1 hour. Thereafter, CA-3(6.57g, 26.3mmol) and NMP (9.5 g) were added, and the mixture was further stirred at 50 ℃ for 12 hours to obtain a polyamic acid solution (PAA-A10) having a resin solid content of 12 mass%. The viscosity of the polyamic acid solution was 375 mPas.

[ Synthesis example 20]

After DA-1(1.12g, 4.5mmol), DA-2(0.59g, 3.0mmol) and DA-3(1.49g, 7.5mmol) were charged in a 100ml four-necked flask with a stirrer and a nitrogen inlet, NMP: GBL ═ 1: 1.0g of the mixed solvent was dissolved by stirring while feeding nitrogen gas. While stirring the solution, CA-2(1.15g, 5.9mmol) and NMP: GBL ═ 1: 1A 10.0g of the solvent was mixed and stirred at 25 ℃ for 1 hour. Thereafter, CA-5(2.60g, 8.8mmol) was added, NMP was added: GBL ═ 1: 1 (1) was mixed with 10.0g of a solvent, and the mixture was further stirred at 50 ℃ for 12 hours to obtain a polyamic acid solution (PAA-A12) having a resin solid content of 12 mass%. The viscosity of the polyamic acid solution was 200 mPas.

Examples 1 to 22 and comparative examples 1 to 6

The polyamic acid solutions obtained in Synthesis examples 1 to 16 and 18 and the polyimide solution obtained in Synthesis example 17 were mixed so as to have a ratio of Polymer 1 to Polymer 2 shown in tables 2-1 and 2-2 below to obtain solutions, and NMP, GBL, BCS, a NMP solution containing LS-46681 wt% and a NMP solution containing AD-13 wt% were added to the obtained solutions under stirring so as to have a composition shown in tables 2-1 and 2-2, and further stirred at room temperature for 2 hours to obtain liquid crystal aligning agents of examples 1 to 22 and comparative examples 1 to 6.

[ Table 2-1]

[ tables 2-2]

< manufacture of liquid crystal display element by Brush-grinding method >

An electrode-equipped glass substrate having dimensions of 30mm × 35mm and a thickness of 0.7mm was prepared. An IZO electrode having a solid pattern for constituting a counter electrode was formed as a1 st layer on the substrate. On the counter electrode of the 1 st layer, a SiN (silicon nitride) film formed by a CVD method was formed as a2 nd layer. The SiN film of the 2 nd layer has a film thickness of 500nm and functions as an interlayer insulating film. On the SiN film of the 2 nd layer, a comb-shaped pixel electrode formed by patterning an IZO film is disposed as a 3 rd layer, thereby forming two pixels, i.e., a1 st pixel and a2 nd pixel. The size of each pixel is: 10mm in length and about 5mm in width. At this time, the counter electrode of the 1 st layer and the pixel electrode of the 3 rd layer are electrically insulated by the SiN film of the 2 nd layer.

The pixel electrode of the layer 3 has a comb-tooth shape in which a plurality of "<" -shaped electrode elements whose central portions are bent are arranged as shown in fig. 3 of jp 2014-77845 a. The width of each electrode element in the width direction was 3 μm, and the interval between the electrode elements was 6 μm. Since the pixel electrode forming each pixel is formed by arranging a plurality of "<" -shaped electrode elements each having a bent central portion, each pixel has a shape similar to a bold "<" shape, in which the central portion is bent in the same manner as the electrode elements, instead of a rectangular shape. Each pixel is divided vertically with a curved portion at the center as a boundary, and has a1 st region on the upper side and a2 nd region on the lower side of the curved portion.

When comparing the 1 st region and the 2 nd region of each pixel, the forming directions of the electrode elements constituting the pixel electrodes are different. That is, when the brushing direction of the liquid crystal alignment film described later is set as a reference, the electrode elements of the pixel electrode are formed so as to make an angle of +10 ° (clockwise) in the 1 st region of the pixel, and the electrode elements of the pixel electrode are formed so as to make an angle of-10 ° (clockwise) in the 2 nd region of the pixel. In addition, the 1 st region and the 2 nd region of each pixel are configured as follows: the directions of the rotational motion (planar inversion) of the liquid crystal in the substrate plane induced by applying a voltage between the pixel electrode and the counter electrode are opposite to each other.

Then, the obtained liquid crystal aligning agent was filtered through a filter having a pore diameter of 1.0 μm, and then spin-coated on the substrate with electrode and a glass substrate having an ITO film formed on the back surface as a counter substrate and a columnar spacer having a height of 4 μm, respectively. Then, the film was dried on a hot plate at 80 ℃ for 5 minutes and then fired at 230 ℃ for 20 minutes to obtain a polyimide film having a film thickness of 60nm on each substrate. On the polyimide film surface, brushing treatment was performed with rayon cloth under conditions of a roll diameter of 120mm, a roll rotation speed of 500rpm, a table moving speed of 30 mm/sec, and a brushing cloth pressing pressure of 0.3mm, and then ultrasonic irradiation was performed in pure water for 1 minute, followed by drying at 80 ℃ for 10 minutes.

The 2 kinds of substrates with the liquid crystal alignment films were combined so that the brushing directions thereof were antiparallel to each other, and the periphery was sealed with the liquid crystal injection port left, thereby producing empty cells with a cell gap of 3.8 μm. After vacuum-injecting a liquid crystal (MLC-3019, manufactured by MERCK CORPORATION) into the empty cell at normal temperature, the injection port was sealed to form an antiparallel aligned liquid crystal cell. The resulting liquid crystal cell constitutes an FFS mode liquid crystal display element. After that, the liquid crystal cell was heated at 120 ℃ for 1 hour, and was placed at night for each evaluation described below.

< evaluation of afterimage elimination time >

Evaluation of afterimage was performed using the following optical system and the like. That is, the manufactured liquid crystal cell was placed between 2 polarizing plates arranged so that the polarizing axes were orthogonal, the LED backlight was turned on in a state where no voltage was applied, and the arrangement angle of the liquid crystal cell was adjusted so that the luminance of transmitted light became minimum. Then, a V-T curve (voltage-transmittance curve) was measured while applying an ac voltage having a frequency of 30Hz to the liquid crystal cell, and an ac voltage having a relative transmittance of 23% was calculated as a driving voltage.

In the image sticking evaluation, the liquid crystal cell was driven by applying an alternating voltage having a frequency of 30Hz and a relative transmittance of 23%, and a direct voltage of 1V was simultaneously applied for 30 minutes. Thereafter, the dc voltage application was set to 0V, and the dc voltage application was stopped only, and the operation was further continued for 15 minutes.

In the afterimage evaluation, the time at which the relative transmittance was reduced to 30% or less was expressed as a numerical value after 30 minutes from the time when the application of the dc voltage was started. Evaluation was performed by defining "O" when the relative transmittance was reduced to 30% or less within 5 minutes and "Δ" when the relative transmittance was reduced to 6 to 30 minutes. When 30 minutes or more was required until the relative transmittance decreased to 30% or less, the residual image was regarded as not erasable and evaluated as "x". The evaluation of the residual image according to the above method was performed under a temperature condition in which the temperature of the liquid crystal cell was 23 ℃.

< evaluation of flicker level immediately after Driving >

The manufactured liquid crystal cell was placed between 2 polarizing plates arranged so that the polarizing axes were orthogonal, the LED backlight was turned on in a state where no voltage was applied, and the arrangement angle of the liquid crystal cell was adjusted so that the brightness of transmitted light became minimum. Then, while an ac voltage having a frequency of 30Hz was applied to the liquid crystal cell, a V-T curve (voltage-transmittance curve) was measured, and an ac voltage having a relative transmittance of 23% was calculated as a driving voltage.

In the measurement of the flicker level, the lit LED backlight was once turned off, left to stand for 72 hours in a light-shielded state, and then the LED backlight was turned on again, and an ac voltage having a frequency of 30Hz and a relative transmittance of 23% was applied simultaneously with the start of lighting of the backlight, and the liquid crystal cell was driven for 60 minutes to track the flicker amplitude. For the flicker amplitude, the transmitted light of the LED backlight passing through the 2 polarizing plates and the liquid crystal cell therebetween was read by a data collection/data logger conversion unit 34970a (Agilent technologies, inc.) connected via a photodiode and an I-V inverting amplifier. The flicker level is calculated by the following mathematical expression.

Flicker level (%) { flicker amplitude/(2 × z) } × 100

In the above equation, z is a value obtained by reading the luminance when the data collector/data recorder conversion unit 34970a is driven under an ac voltage of 30Hz at a frequency at which the relative transmittance becomes 23%.

Regarding the flicker level, a case where the flicker level was maintained at less than 3% until 60 minutes elapsed from the time when the LED backlight was turned on and the application of the ac voltage was started was evaluated as "o". The case where the flicker level reached 3% or more in 60 minutes was evaluated as "x".

Further, the evaluation of the flicker level according to the above method was performed under the temperature condition that the temperature of the liquid crystal cell was 23 ℃.

< evaluation result >

The results of the evaluation of the afterimage erasing time and the evaluation of the flicker level immediately after driving in the liquid crystal display elements using the liquid crystal aligning agents of examples 1 to 22 and comparative examples 1 to 5 are shown in table 3.

[ Table 3]

< production of liquid Crystal display element by photo-alignment method >

After the liquid crystal aligning agent was filtered through a filter having a pore size of 1.0 μm, the liquid crystal aligning agent was spin-coated on the prepared substrate with electrodes and a glass substrate having an ITO film formed on the back surface as a counter substrate and a columnar spacer having a height of 4 μm, respectively. After drying on a hot plate at 80 ℃ for 5 minutes, the film was baked at 230 ℃ for 30 minutes to form a coating film having a thickness of 100nm, thereby obtaining a polyimide film on each substrate. The coated surface was irradiated with a polarizing plate to obtain a film having an extinction ratio of 26: 1 linearly polarized ultraviolet ray of 300mJ/cm at a wavelength of 254nm². The substrate was heated on a hot plate at 230 ℃ for 30 minutes to obtain a substrate with a liquid crystal alignment film. The 2 substrates were used as a set, a sealant was printed on the substrates, and another 1 substrate was bonded so that the liquid crystal alignment films face each other and the alignment direction was 0 °, and then the sealant was cured to prepare an empty cell. The FFS-driven liquid crystal cell was obtained by injecting negative type liquid crystal MLC-7026-100 (manufactured by MERCK CORPORATION) into the empty cell by a reduced pressure injection method and sealing the injection port. Then, the resulting liquid crystal cell was heated at 110 ℃ for 1 hour, and placed late for each evaluation described below.

< evaluation of afterimage elimination time >

The optical system of the liquid crystal display element by the photo-alignment method prepared in the above was used to evaluate the image sticking, as in the case of the liquid crystal display element by the rubbing method.

In the evaluation of the image sticking, unlike the case of the liquid crystal display element by the brush-out method, the time for decreasing the relative transmittance to 23% was expressed as a numerical value after 30 minutes from the start of applying the dc voltage. When the relative transmittance is reduced to 23% within 5 minutes, it is defined as "O", and when the relative transmittance is reduced to 6 to 30 minutes, it is defined as "Δ". When 30 minutes or more was required until the relative transmittance decreased to 23%, the residual image was regarded as "x".

< evaluation of flicker level immediately after Driving >

Similarly to the case of the liquid crystal display element by the rubbing method, the optical system of the liquid crystal display element by the photo-alignment method prepared above was used to evaluate the image sticking.

< evaluation result >

The results of the evaluation of the afterimage erasing time and the evaluation of the flicker level immediately after driving performed on the liquid crystal display element using the liquid crystal aligning agent obtained in example 19 and comparative example 6 are shown in table 4.

[ Table 4]

As can be seen from tables 3 and 4, the liquid crystal display element using the liquid crystal aligning agent of the example of the present invention has a fast relaxation of the accumulated charge and hardly causes a flicker shift immediately after the start of driving.

Industrial applicability

The liquid crystal aligning agent using the novel polymer of the present invention is widely used in liquid crystal display devices of a vertical electric field system such as a TN system and a VA system, and particularly a horizontal electric field system such as an IPS system and an FFS system.

The entire contents of the specification, claims and abstract of japanese patent application 2016-.

Claims

1. A liquid crystal aligning agent, comprising: a polymer obtained from a diamine having a structure represented by the following formula (1); and, an organic solvent,

R₁represents a hydrogen atom, a fluorine atom, a cyano group, a hydroxyl group or a monovalent organic group, represents a site bonded to other groups, and any hydrogen atom of the benzene ring is optionally substituted with a monovalent organic group.

2. The liquid crystal aligning agent according to claim 1, wherein the polymer is at least 1 polymer selected from the group consisting of a polyimide precursor which is a polycondensate of a diamine having the structure represented by the formula (1) and a tetracarboxylic dianhydride, and a polyimide which is an imide compound of the polyimide precursor.

3. The liquid crystal aligning agent according to claim 1 or 2, wherein the diamine is represented by the following formula (2),

R₁is as defined for said formula (1), 2R₂Each independently represents a single bond or a structure represented by the following formula (3), n represents an integer of 1 to 3, any hydrogen atom of the benzene ring is optionally substituted by a 1-valent organic group,

R₃represents a single bond selected from-O-, -COO-, -OCO-, - (CH)₂)_l-、-O(CH₂)_m2-valent organic groups in O-, -CONH-and-NHCO-, wherein l and m represent integers of 1 to 5₁Represents a site bonded to a benzene ring in the formula (2)₂Represents a site bonded to an amino group in formula (2).

4. The liquid crystal aligning agent according to claim 2, wherein the polyimide precursor has a structural unit represented by the following formula (6),

X₁is a 4-valent organic radical derived from a tetracarboxylic acid derivative, Y₁Is a 2-valent organic group derived from a diamine comprising the structure of formula (1), R₄Is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.

5. The liquid crystal aligning agent according to claim 4, wherein in the formula (6), X₁Is at least 1 selected from the group consisting of the following structures of the formulae (A-1) to (A-21),

6. the liquid crystal aligning agent according to claim 4 or 5, wherein the polymer having the structural unit represented by the formula (6) is contained in an amount of 10 mol% or more based on the total polymer contained in the liquid crystal aligning agent.

7. The liquid crystal aligning agent according to claim 1 or 2, wherein the organic solvent contains at least 1 selected from the group consisting of 4-hydroxy-4-methyl-2-pentanone and diethylene glycol diethyl ether.

8. A liquid crystal alignment film obtained from the liquid crystal aligning agent according to any one of claims 1 to 7.

10. The liquid crystal display element according to claim 9, wherein the liquid crystal display element is of a lateral electric field driving type.

11. A polymer which is at least 1 selected from the group consisting of a polyimide precursor which is a polycondensate of a diamine having a structure represented by the following formula (1) and a tetracarboxylic dianhydride, and a polyimide which is an imide compound of the polyimide precursor,

as defined in claim 1;

R₁represents hydrogen, a fluorine atom, a cyano group, a hydroxyl group, or a monovalent organic group which is an alkyl group, an alkenyl group, an alkoxy group, a fluoroalkyl group, a fluoroalkenyl group, or a fluoroalkoxy group, and has 1 to 10 carbon atoms.

12. The polymer according to claim 11, wherein the diamine is represented by the following formula (2),

R₁as defined in claim 11;

R₂and n is as defined in claim 3.

13. The polymer according to claim 11 or 12, wherein the polyimide precursor is represented by the following formula (6),

X₁、Y₁and R₄As defined in claim 4.

14. The polymer of claim 13, wherein the polymer is a poly (ethylene-co-propylene copolymer)In the formula (6), X₁Is at least 1 selected from the group consisting of the structures of the formulae (A-1) to (A-21) described in claim 5.