JPWO2017065226A1 - Liquid crystal aligning agent, liquid crystal aligning film, and liquid crystal display element - Google Patents

Abstract

（Ｒ_１は水素、又は一価の有機基であり、Ａｒは、置換基を有してもよいフェニル基若しくはナフタレン基であり、＊は他の基に結合する部位を示す。）Liquid crystal aligning agent with excellent rubbing resistance, quick relaxation of accumulated charge, and high alignment regulating power, liquid crystal aligning agent excellent in display characteristics, especially horizontal electric field type liquid crystal display element, and raw material for the liquid crystal aligning agent A novel diamine is provided.
The liquid crystal aligning agent containing the polymer which has a structure represented by following formula (1) in a principal chain.
[Chemical 1]

(R ₁ is hydrogen or a monovalent organic group, Ar is a phenyl group or a naphthalene group which may have a substituent, and * represents a site bonded to another group.)

Description

  The present invention relates to a liquid crystal aligning agent, a liquid crystal aligning film, a liquid crystal display element, and a novel diamine compound used as a raw material for a polymer contained in the liquid crystal aligning agent.

  Liquid crystal display elements are widely used as display units for smartphones, personal computers, mobile phones, televisions, and the like. The liquid crystal display element includes, for example, a liquid crystal layer sandwiched between an element substrate and a color filter substrate, a pixel electrode and a common electrode that apply an electric field to the liquid crystal layer, an alignment film that controls the alignment of liquid crystal molecules in the liquid crystal layer, and a pixel A thin film transistor (TFT) for switching an electric signal supplied to the electrode is provided. As a driving method of liquid crystal molecules, a vertical electric field method such as a TN method and a VA method, and a horizontal electric field method such as an IPS method and an FFS method are known. The horizontal electric field method in which an electrode is formed only on one side of the substrate and an electric field is applied in a direction parallel to the substrate is wider than the vertical electric field method in which voltage is applied to the electrodes formed on the upper and lower substrates to drive the liquid crystal. It is known as a liquid crystal display element having viewing angle characteristics and capable of high-quality display.

  Although the horizontal electric field type liquid crystal cell is excellent in viewing angle characteristics, since there are few electrode portions formed in the substrate, if the voltage holding ratio is low, a sufficient voltage is not applied to the liquid crystal and the display contrast is lowered. Further, if the stability of the liquid crystal alignment is small, the liquid crystal does not return to the initial state when the liquid crystal is driven for a long time, which causes a decrease in contrast and an afterimage. Therefore, the stability of the liquid crystal alignment is important. In addition, static electricity is easily accumulated in the liquid crystal cell, and charges are accumulated in the liquid crystal cell even when a positive / negative asymmetric voltage generated by driving is applied. These accumulated charges affect the display as a disorder of liquid crystal alignment or an afterimage. The display quality of the liquid crystal element is significantly reduced. In addition, charges are accumulated by irradiating the liquid crystal cell with backlight light immediately after driving, and afterimages are generated even during short-time driving, and the size of flicker (flicker) changes during driving. It will occur.

  On the other hand, in the manufacturing process of a liquid crystal display element, the liquid crystal alignment film is generally formed by printing a liquid crystal aligning agent, performing drying and baking, and then performing a rubbing treatment. The lateral electric field type liquid crystal cell has an electrode structure only on one side of the substrate, so that the substrate has large irregularities, and an insulator such as silicon nitride is sometimes formed on the surface of the substrate. Therefore, a liquid crystal aligning agent having more excellent printability is required. Furthermore, since the rubbing treatment is applied stronger than conventional liquid crystal cells in order to improve the stability of the liquid crystal alignment, peeling and rubbing due to the rubbing treatment are likely to occur, and these peelings and scratches deteriorate the display quality. There is a point.

Patent Document 1 discloses a liquid crystal containing a specific diamine and an aliphatic tetracarboxylic acid derivative as a liquid crystal aligning agent having excellent voltage holding ratio and reduced charge accumulation when used in such a lateral electric field drive liquid crystal element. An alignment agent is disclosed. In addition, as a means for forming a liquid crystal alignment film that is excellent in liquid crystal alignment, rubbing resistance, and light transmittance and effective in reducing afterimages over a wide temperature range, Patent Document 2 discloses specific diamines and aromatic tetracarboxylic acid derivatives. A liquid crystal aligning agent is disclosed. As a liquid crystal aligning agent excellent in liquid crystal alignment without decreasing the voltage holding ratio even when a thermal stress is applied for a long time, Patent Document 3 is selected from the group consisting of polyamic acid and polyimide having a specific structure. A liquid crystal aligning agent containing at least one polymer is disclosed.
However, with the improvement in performance of liquid crystal display elements, the characteristics required for the liquid crystal alignment film are becoming stricter, and it is difficult to satisfy all the required characteristics only with the conventional technology.

International Publication WO2004 / 021076 Pamphlet International Publication No. WO2013 / 062115 Pamphlet JP2010-026503

  An object of the present invention is to obtain a liquid crystal alignment film that is excellent in rubbing resistance, has a fast relaxation of accumulated charges, and has a high stability of liquid crystal alignment, and is particularly suitable for a liquid crystal display element for a lateral electric field drive system.

（Ｒ_１は水素、又は一価の有機基を表す。Ａｒは、置換基を有してもよいフェニル基若しくはナフタレン基である＊は他の基に結合する部位を示す。）As a result of intensive studies to solve the above problems, the present inventors have found that various properties can be improved simultaneously by introducing a specific structure into the polymer contained in the liquid crystal aligning agent. Completed the invention.
The gist of the present invention is as follows.
1. The liquid crystal aligning agent containing the polymer which has a structure represented by following formula (1) in a principal chain.

(R ₁ represents hydrogen or a monovalent organic group. Ar represents a phenyl group or naphthalene group which may have a substituent. * Represents a site bonded to another group.)

  According to the liquid crystal aligning agent of the present invention, the liquid crystal alignment film excellent in rubbing resistance, quickening of accumulated charge, and high in alignment regulating power, particularly suitable for a liquid crystal display element for a lateral electric field drive system, and excellent display characteristics. In particular, a lateral electric field drive type liquid crystal display element is provided.

式（１）のＲ_１は水素、又は一価の有機基を表す。一価の有機基としては、炭素数１〜２０のアルキル基やアルケニル基、シクロアルキル基、フェニル基、フッ素原子、又はこれらの組み合わせからなる基などが挙げられる。なかでも、水素原子、又は炭素数１〜３の直鎖アルキル基が好ましく、水素原子、又はメチル基がより好ましくい。The liquid crystal aligning agent of this invention is a liquid crystal aligning agent containing the polymer (henceforth a specific polymer) which has a bivalent group represented by following formula (1) in a principal chain.

R _{1 in} formula (1) represents hydrogen or a monovalent organic group. Examples of the monovalent organic group include a group having 1 to 20 carbon atoms, an alkenyl group, a cycloalkyl group, a phenyl group, a fluorine atom, or a combination thereof. Especially, a hydrogen atom or a C1-C3 linear alkyl group is preferable, and a hydrogen atom or a methyl group is more preferable.

R ₁ may be a protecting group that undergoes elimination reaction by heat and replaces a hydrogen atom. From the viewpoint of the storage stability of the liquid crystal aligning agent, this protecting group does not desorb at room temperature, and preferably desorbs at 80 ° C. or higher, more preferably 100 ° C. or higher, particularly preferably 150 to 200 ° C. It is preferable to become. Examples thereof include a 1,1-dimethyl-2-chloroethoxycarbonyl group, a 1,1-dimethyl-2-cyanoethoxycarbonyl group, a tert-butoxycarbonyl group, and the like, and preferably a tert-butoxycarbonyl group.
Ar in Formula (1) represents a phenyl group or a naphthalene group which may have a substituent. Of these, a phenyl group is preferred. Moreover, the substituent may be couple | bonded with the ring part of these phenyl groups or naphthalene groups. Specific examples of the substituent include a fluorine atom and a methyl group.

  In the present invention, the type of the polymer having a divalent group represented by the formula (1) in the main chain is not particularly limited. Specific examples include polymers generally used as liquid crystal alignment films, such as polyamide, polyamic acid, polyamic acid ester, polyimide, polyurea, polysiloxane, and polyester. Among these, a polyimide precursor such as polyamic acid or polyamic acid ester, or at least one polymer among polyimides obtained by imidizing it is preferable.

  As said polyimide precursor, the polyamic acid or polyamic acid ester obtained by reaction with a tetracarboxylic-acid derivative and diamine is mentioned. As means for introducing a divalent group represented by the formula (1) into the main chain of the polyimide precursor, a tetracarboxylic acid derivative having a divalent group represented by the formula (1) in the main chain direction. Or a method in which at least one selected from diamines having a divalent group represented by the formula (1) in the main chain direction is used for a part or all of the tetracarboxylic acid derivative and diamine used in the above reaction. Can be mentioned.

  Examples of the tetracarboxylic acid derivative used in the production of the polyimide precursor include tetracarboxylic acid, tetracarboxylic dianhydride, tetracarboxylic acid dihalide, tetracarboxylic acid dialkyl ester, and tetracarboxylic acid dialkyl ester dihalide. For example, a tetracarboxylic acid having a divalent group represented by the formula (1) in the main chain direction can be represented by the following formula (1-1).

式（１−１）中、Ｒ_１及びＡｒは前記式（１）の定義と同じであり、Ａは３価の基を表し、２つのＡは同一であっても異なってもよい。Ａの例としては、シクロブタン環構造、シクロペンタン環構造、シクロヘキサン環構造、ベンゼン環構造及び下記式（Ａ−１）よりなる群から選ばれる少なくとも一種を有する３価の有機基が挙げられる。

In Formula (1-1), R ₁ and Ar are the same as defined in Formula (1), A represents a trivalent group, and two A may be the same or different. Examples of A include a trivalent organic group having at least one selected from the group consisting of a cyclobutane ring structure, a cyclopentane ring structure, a cyclohexane ring structure, a benzene ring structure and the following formula (A-1).

式（１−２）中、Ｒ_１及びＡｒは前記式（１）の定義と同じであり、Ｂは単結合又は２価の基を表し、２つのＢは同一であっても異なってもよい。Ｂが２価の基である場合、その例としては、ベンゼン環構造、炭素数が１〜１０、好ましくは１〜５を有する、アルキル構造、アルケニル構造、アルコキシ構造、フルオロアルキル構造、及びアミド構造よりなる群から選ばれる少なくとも一種を有する２価の有機基が挙げられる。Moreover, the diamine which has a bivalent group represented by Formula (1) in a principal chain direction can be represented by following formula (1-2).

In Formula (1-2), R ₁ and Ar are the same as defined in Formula (1), B represents a single bond or a divalent group, and two Bs may be the same or different. . When B is a divalent group, examples thereof include a benzene ring structure, an alkyl structure, an alkenyl structure, an alkoxy structure, a fluoroalkyl structure, and an amide structure having 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms. And a divalent organic group having at least one selected from the group consisting of:

  The diamine represented by the above formula (1-2) can also be used to obtain a polyurea having a divalent group represented by the formula (1) in the main chain direction. Polyurea is obtained by the reaction of diisocyanate and diamine, and polyurea obtained by using the diamine of formula (1-2) in part or all of this reaction is the specific polymer contained in the liquid crystal aligning agent of the present invention. It becomes a kind.

The specific polymer used in the present invention is preferably at least one selected from a polyimide precursor containing a structural unit represented by the following formula (2) and a polyimide obtained by imidizing it.

In the above formula (2), X ₁ is a tetravalent organic group derived from a tetracarboxylic acid derivative. Y ₁ is a divalent organic group derived from a diamine containing the structure of formula (1) in the main chain direction. R ₂ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R ₂ is preferably a hydrogen atom, a methyl group or an ethyl group from the viewpoint of ease of imidization by heating.

X ₁ depends on the required properties such as solubility of the polymer in the solvent, coating property of the liquid crystal aligning agent, orientation of the liquid crystal when the liquid crystal aligning film is used, voltage holding ratio, accumulated charge, and the like. It is appropriately selected, and one type or two or more types may be used in the same polymer.
If Specific examples of X _1, are listed in paragraph 13 to 14, wherein the WO 2015/119168, such as the structure of formula (X-1) ~ (X -46) are mentioned.

Below, shows the structure of a preferred X _1, the present invention is not limited thereto.

Among the above structures, (A-1) and (A-2) are particularly preferable from the viewpoint of further improving the rubbing resistance. (A-4) is particularly preferable from the viewpoint of further improving the rate of relaxation of accumulated charges. (A-15) to (A-17) are particularly preferable from the viewpoint of further improving the liquid crystal orientation and the relaxation rate of the accumulated charges.
In Formula (2), specific examples of Y ₁ include a structure in which two amino groups are removed from the diamine of Formula (1-2). Of these, Y ₁ is more preferably a structure of the following formula (3).

式（３）において、Ｒ_１及びＡｒは前記式（１）の定義と同じである。Ｒ_３は単結合又は置換基を有してもよいフェニル基を表す。＊は―ＮＨ−に結合する部位を示す。Ｒ_３はフェニル基が特に好ましい。

In Formula (3), R ₁ and Ar are the same as defined in Formula (1). R ₃ represents a single bond or a phenyl group which may have a substituent. * Indicates a site bonded to -NH-. R ₃ is particularly preferably a phenyl group.

A particularly preferred structure of Y ₁ is shown below. In the following formula, Boc represents a tert-butoxycarbonyl group, and * represents a site bonded to —NH—.

式（４）において、Ｒ_１及びＡｒは上記式（１）の定義と同じである。Ｒ_３は単結合、又は置換基を有してもよいフェニル基を表す。Ｒ_３はフェニル基が特に好ましい。In addition, as diamine which has a structure of said Formula (3), the diamine represented by following formula (4) can be mentioned. A method for producing such a diamine will be described later.

In the formula (4), R ₁ and Ar are the same as defined in the above formula (1). R ₃ represents a single bond or a phenyl group which may have a substituent. R ₃ is particularly preferably a phenyl group.

The polyimide precursor containing the structural unit represented by the formula (2) may contain a structural unit represented by the following formula (5) as long as the effects of the present invention are not impaired.

In the formula (5), X ₂ is a tetravalent organic group derived from a tetracarboxylic acid derivative. Y ₂ is a divalent organic group derived from a diamine that does not include the structure of Y 1 in the formula (1) in the main chain direction. R ₂ is the same as defined in Formula (2), and R ₄ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Moreover, it is preferable that at least one of two R < ₄ > is a hydrogen atom.

Specific examples of X ₂ include the same structures as those exemplified for X ₁ in formula (2), including preferred examples. Y ₂ is a divalent organic group derived from a diamine that does not contain the structure of formula (1) in the main chain direction, and the structure is not particularly limited. Y ₂ depends on the degree of required properties such as the solubility of the polymer in the solvent, the coating property of the liquid crystal aligning agent, the orientation of the liquid crystal when it is used as the liquid crystal alignment film, the voltage holding ratio, and the accumulated charge. And may be one type or two or more types in the same polymer.

If Specific examples of Y _2, the structure of the formulas listed in page 4 of WO 2015/119168 (2), and is posted on 8-12 pages, Formula (Y-1) ~ (Y -97), (Y-101) to (Y-118); a divalent organic group obtained by removing two amino groups from the formula (2) described in paragraph 6 of International Publication No. 2013/008906; Divalent organic group obtained by removing two amino groups from formula (1) published on page 8 of publication 2015/122413; formula (3) published on page 8 of international publication 2015/060360; A divalent organic group obtained by removing two amino groups from Formula (1) described on page 8 of Patent Publication 2012-173514; Formulas (A) to (F) published on page 9 of International Publication 2010-050523 And divalent organic groups obtained by removing two amino groups from The

It shows the preferred structure of Y ₂ below, but the invention is not limited thereto.

  Among the above, (B-28) and (B-29) are particularly preferable from the viewpoint of further improving rubbing resistance. (B-1) to (B-3) are particularly preferable from the viewpoint of further improving the liquid crystal orientation. (B-14) to (B-18) and (B-27) are particularly preferable from the viewpoint of further improving the relaxation rate of accumulated charges.

When the polyimide precursor containing the structural unit represented by Formula (2) includes the structural unit represented by Formula (5), the structural unit represented by Formula (2) is represented by Formula (2) and Formula ( It is preferable that it is 10 mol% or more with respect to the sum total of 5), More preferably, it is 20 mol% or more, Most preferably, it is 30 mol% or more.
The molecular weight of the polyimide precursor used in the present invention is preferably 2,000 to 500,000 in terms of weight average molecular weight, more preferably 5,000 to 300,000, and still more preferably 10,000 to 100,000. is there.

Examples of the polyimide having a divalent group represented by the formula (1) in the main chain include a polyimide obtained by ring-closing the polyimide precursor. In this polyimide, the ring closure rate (also referred to as imidation rate) of the amic acid group is not necessarily 100%, and can be arbitrarily adjusted according to the use and purpose.
Examples of the method for imidizing the polyimide precursor include thermal imidization in which the polyimide precursor solution is heated as it is, or catalytic imidization in which a catalyst is added to the polyimide precursor solution.

  Although the liquid crystal aligning agent of this invention contains the said specific polymer, it may contain 2 or more types of specific polymers of a different structure. Further, in addition to the specific polymer, other polymers, that is, polymers having no divalent group represented by the formula (1) in the main chain may be contained. Other polymer types include polyamic acid, polyimide, polyamic acid ester, polyester, polyamide, polyorganosiloxane, cellulose derivative, polyacetal, polystyrene or derivatives thereof, poly (styrene-phenylmaleimide) derivative, poly (meth) acrylate. And so on. When the liquid crystal aligning agent of this invention contains another polymer, it is preferable that the ratio of the specific polymer with respect to all the polymer components contained is 5 mass% or more, and 5-95 mass% is mentioned as the example. It is done.

  The liquid crystal aligning agent is used for producing a liquid crystal aligning film, and generally takes the form of a solution from the viewpoint of forming a uniform thin film. Also in the liquid crystal aligning agent of this invention, it is preferable that it is a solution containing an above-described polymer component and the organic solvent in which this polymer component is dissolved. At that time, 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. From the viewpoint of forming a uniform and defect-free coating film, the content is preferably 1% by mass or more, and from the viewpoint of storage stability of the solution, it is preferably 10% by mass or less. A particularly preferable concentration of the polymer is 2 to 8% by mass.

  The organic solvent contained in the liquid crystal aligning agent is not particularly limited as long as the polymer component is uniformly dissolved. Specific examples include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, 1,3-dimethyl. -Imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone and the like can be mentioned. Among these, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, or γ-butyrolactone is preferably used.

  Moreover, the organic solvent contained in the liquid crystal aligning agent uses a mixed solvent that is used in combination with a solvent that improves the coating properties and the surface smoothness of the coating film when the liquid crystal aligning agent is applied in addition to the above-described solvents. Such a mixed solvent is also preferably used in the liquid crystal aligning agent of the present invention. Specific examples of the organic solvent to be used in combination are as disclosed in various known literatures relating to liquid crystal aligning agents. For example, pages 53 [0104] to 55 of the pamphlet of International Publication No. 2015/060357. And the solvent disclosed in [0105]. The kind and content of such a solvent are appropriately selected according to the application device, application conditions, application environment, and the like of the liquid crystal aligning agent.

  The liquid crystal aligning agent of this invention may contain additionally components other than a polymer component and an organic solvent in the range which does not impair the effect of this invention. Examples of such additional components include an adhesion aid for increasing the adhesion between the liquid crystal alignment film and the substrate and the adhesion between the liquid crystal alignment film and the sealing material, a crosslinking agent for increasing the strength of the liquid crystal alignment film, and the liquid crystal alignment. Examples thereof include dielectrics and conductive materials for adjusting the dielectric constant and electric resistance of the film. Specific examples of these additional components are as disclosed in various known literatures relating to liquid crystal aligning agents. For example, page 53 [0105] to page 55 of International Publication No. 2015/060357. Ingredients disclosed in [0116].

If an example of the method of obtaining a liquid crystal aligning film from the liquid crystal aligning agent of this invention is given, the liquid-crystal aligning agent of a coating liquid form will be apply | coated to a board | substrate, it will dry, and it will rub with respect to the film | membrane obtained by baking. The method of performing an alignment process by the alignment process method is mentioned.
The substrate to which the liquid crystal alignment agent is applied is not particularly limited as long as it is a highly transparent substrate, and a plastic substrate such as an acrylic substrate or a polycarbonate substrate can be used together with a glass substrate or a silicon nitride substrate. At that time, it is preferable to use a substrate on which an ITO electrode or the like for driving the liquid crystal is used from the viewpoint of simplification of the process. In the reflective liquid crystal display element, an opaque object such as a silicon wafer can be used as long as only one substrate is used, and a material that reflects light such as aluminum can be used for the electrode in this case.

The method for applying the liquid crystal aligning agent is not particularly limited, but screen printing, offset printing, flexographic printing, inkjet method, and the like are common. Other coating methods include a dipping method, a roll coater method, a slit coater method, a spinner method, and a spray method, and these may be used depending on the purpose.
After the liquid crystal aligning agent is applied on the substrate, the solvent is evaporated and baked by a heating means such as a hot plate, a thermal circulation oven, an IR (infrared) oven, or the like. Arbitrary temperature and time can be selected for the drying and baking steps after applying the liquid crystal aligning agent. Usually, in order to sufficiently remove the contained solvent, there is a means of baking at 50 to 120 ° C. for 1 to 10 minutes and then baking at 150 to 300 ° C. for 5 to 120 minutes.

Although the thickness of the liquid crystal aligning film after baking is not specifically limited, Since the reliability of a liquid crystal display element may fall when too thin, it is preferable that it is 5-300 nm, and 10-200 nm is more preferable.
The liquid crystal alignment film of the present invention is suitable as a liquid crystal alignment film of a horizontal electric field type liquid crystal display element such as an IPS mode or an FFS mode, and is particularly useful as a liquid crystal alignment film of an FFS mode liquid crystal display element.
The liquid crystal display device of the present invention is a device in which a liquid crystal cell is prepared by a known method after obtaining a substrate with a liquid crystal alignment film obtained from the liquid crystal aligning agent, and the liquid crystal cell is used as an element.

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 as an example. Note that an active matrix liquid crystal display element in which a switching element such as a TFT (Thin Film Transistor) is provided in each pixel portion constituting the image display may be used.
Specifically, a transparent glass substrate is prepared, a common electrode is provided on one substrate, and a segment electrode is provided on the other substrate. These electrodes can be ITO electrodes, for example, and are patterned so as to display a desired image. Next, an insulating film is provided on each substrate so as to cover the common electrode and the segment electrode. The insulating film can be, for example, a film made of SiO ₂ —TiO ₂ formed by a sol-gel method. Next, a liquid crystal alignment film is 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 two substrates on which the liquid crystal alignment film is formed, and liquid crystals are disposed at predetermined positions on the liquid crystal alignment film surface. After that, the other substrate is bonded and pressure-bonded so that the liquid crystal alignment film faces, and the liquid crystal is spread on the front surface of the liquid crystal alignment film, and then the entire surface of the substrate is irradiated with ultraviolet rays to cure the sealing material. Get a cell.

In addition, as a step after forming the liquid crystal alignment film on the substrate, an opening that can be filled with liquid crystal from the outside is provided when a sealing material is disposed at a predetermined location on one substrate. After the substrates are bonded without being arranged, a liquid crystal material is injected into the liquid crystal cell through an 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 utilizing capillary action in the atmosphere.
In any of the above methods, in order to secure a space filled with a liquid crystal material in the liquid crystal cell, columnar protrusions are provided on one substrate, spacers are scattered on one substrate, or a sealing material It is preferable to take a means such as mixing a spacer with these or combining them.

Examples of the liquid crystal material include a nematic liquid crystal and a smectic liquid crystal. Among them, a nematic liquid crystal is preferable, and either a positive liquid crystal material or a negative liquid crystal material may be used. Next, a polarizing plate is installed. Specifically, it is preferable to attach a pair of polarizing plates to the surfaces of the two 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 aligning agent of the present invention is used, and may be manufactured by other known methods. Good. The process from obtaining a liquid crystal display element from a liquid crystal aligning agent is disclosed, for example, in Japanese Patent Application Laid-Open No. 2015-135393, page 17 [0074] to page 19 [0081].

<Diamine of the present invention>
Hereinafter, a method for obtaining the diamine represented by the following formula (4) will be described.

In the formula (4), R ₁ and Ar are the same as defined in the above formula (1). R ₃ represents a single bond or a phenyl group which may have a substituent. R ₃ is particularly preferably a phenyl group.
Preferable specific examples of the diamine represented by the formula (4) include diamines represented by the following formulas (4-1) to (4-7). In the formula, Boc represents a tert-butoxycarbonyl group, and Me represents a methyl group.

Although the method to manufacture diamine represented by the said Formula (4) is not specifically limited, As the preferable method, the following manufacturing methods are mentioned.
The following dinitro compound (a3) is produced by reacting an amine compound (a1) having a thiazole skeleton with a nitro compound (a2). Thereafter, the target diamine (a4) can be obtained by reducing the nitro group.

In the reaction formulas [1] and [2], R ′ and R ″ are monovalent organic groups, X represents a halogen atom, and represents an F, Cl, Br, or I atom.
The above is an example when R ₁ in formula (4) is a hydrogen atom. When R ₁ is other than a hydrogen atom, a monovalent organic group corresponding to R ₁ is introduced into the dinitro compound (a3). That's fine. In order to introduce a monovalent organic group, any compound capable of reacting with amines may be used. For example, acid halides, acid anhydrides, isocyanates, epoxies, oxetanes, halogenated aryls, halogenated alkyls. Kind. In addition, alcohols in which a hydroxyl group of alcohol is substituted with a leaving group such as OMs, OTf, OTs, or the like can be used.

The method for synthesizing the amine compound (a1) having a thiazole skeleton is not particularly limited. As a general synthesis method, as shown below, the amine compound (a1) is synthesized by reacting an α-haloketone (a5) having a nitro group with thiourea. be able to.

  Examples of the base used include inorganic bases such as sodium hydrogen carbonate, potassium hydrogen carbonate, potassium phosphate, sodium carbonate, potassium carbonate, lithium carbonate, cesium carbonate, trimethylamine, triethylamine, tripropylamine, triisopropylamine, tributylamine, diisopropyl Amines such as ethylamine, pyridine, quinoline and collidine, and bases such as sodium hydride and potassium hydride can be used.

  As for the solvent, any solvent that does not react with the raw material can be used, and aprotic polar organic solvents (N, N-dimethylformamide, dimethyl sulfoxide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, etc. ), Ethers (diethyl ether, diisopropyl ether, methyl tertbutyl 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.), halogenated hydrocarbons (chloroform, dichloromethane, carbon tetrachloride, dichloroethane, etc.), lower fatty acid esters (methyl acetate) , Ethyl acetate, butyl acetate, methyl propionate, etc.) and nitriles (acetonitrile, propionitrile, butyronitrile, etc.) can be used. These solvents can be appropriately selected in consideration of the ease of reaction and the like. In this case, the above solvents can be used alone or in combination of two or more. In some cases, an appropriate dehydrating agent or desiccant can be used as a non-aqueous solvent. Although reaction temperature can select arbitrary temperature in the range from -100 degreeC to the boiling point of the solvent to be used, Preferably it is the range of -50-150 degreeC. The reaction time can be arbitrarily selected within the range of 0.1 to 1000 hours. The product may be purified by recrystallization, distillation, silica gel column chromatography or the like.

With respect to the above reaction formula [1], if X is F or Cl and the NO ₂ group is at the 2-position or 4-position with respect to X, the aryl halide and aliphatic amine compound in the presence of a base Can be reacted to obtain the dinitro compound (a3). As the base to be used, the above-mentioned bases can be used. The reaction solvent and reaction temperature are as described above. The product may be purified by recrystallization, distillation, silica gel column chromatography or the like.

If X is Br or I, the NO ₂ group may be 2-position, 3-position or 4-position relative to X, and C—N cross-coupling in the presence of a suitable metal catalyst, ligand and base A dinitro compound can also be obtained by using a reaction. Examples of metal catalysts include palladium acetate, palladium chloride, palladium chloride-acetonitrile complex, palladium-activated carbon, bis (dibenzylideneacetone) palladium, tris (dibenzylideneacetone) dipalladium, bis (acetonitrile) dichloropalladium, bis (benzo Nitrile) dichloropalladium, CuCl, CuBr, CuI, CuCN and the like. Examples of ligands include triphenylphosphine, tri-o-tolylphosphine, diphenylmethylphosphine, phenyldimethylphosphine, 1,2-bis (diphenylphosphino) ethane, 1,3-bis (diphenylphosphino) propane 1,4-bis (diphenylphosphino) butane, 1,1′-bis (diphenylphosphino) ferrocene, trimethyl phosphite, triethyl phosphite, triphenyl phosphite, tri-tert-butylphosphine and the like. As examples of the base, the aforementioned bases can be used. The reaction solvent and reaction temperature are the same as described above. The product may be purified by recrystallization, distillation, silica gel column chromatography or the like.

The reduction reaction applied to the above reaction [2] includes a hydrogenation reaction in the presence of a catalyst, a reduction reaction performed in the presence of protons, a reduction reaction using formic acid as a hydrogen source, a reduction reaction using hydrazine as a hydrogen source, and the like. These reduction reactions may be combined. In view of the structure of the dinitro compound and the reactivity of the reduction reaction, a hydrogenation reaction is preferred.
The catalyst used for the reduction reaction is preferably an activated carbon-supported metal available as a commercial product, and examples thereof include palladium-activated carbon, platinum-activated carbon, and rhodium-activated carbon. Further, the catalyst may not necessarily be an activated carbon-supported metal catalyst such as palladium hydroxide, platinum oxide, or Raney nickel. Palladium-activated carbon that is generally widely used is preferred because good results are obtained.

  In order to make the reduction reaction proceed more effectively, the reaction may be carried out in the presence of activated carbon. At this time, the amount of the activated carbon to be used is not particularly limited, but is preferably in the range of 1 to 30% by mass, more preferably 10 to 20% by mass with respect to the dinitro compound (a3, X1). For the same reason, the reaction may be carried out under pressure. In this case, in order to avoid reduction of benzene nuclei, it is carried out in a pressure range up to 20 atm. The reaction is preferably carried out in the range up to 10 atm.

  If a solvent does not react with each raw material, it can be used without a restriction | limiting. For example, aprotic polar organic solvents (N, N-dimethylformamide, dimethyl sulfoxide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, etc.); ethers (diethyl ether, diisopropyl ether, methyl tertbutyl 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.) ); Halogenated hydrocarbons (chloroform, dichloromethane, carbon tetrachloride, dichloroethane, etc.); lower fatty acid esters (methyl acetate, ethyl acetate, butyl acetate, methyl propionate, etc.); Rils (acetonitrile, propionitrile, butyronitrile, etc.); These solvents can be appropriately selected in consideration of the ease of reaction and the like, and can be used singly or in combination of two or more. If necessary, the solvent can be dried using a suitable dehydrating agent or desiccant and used as a non-aqueous solvent.

Although the usage-amount (reaction concentration) of a solvent is not specifically limited, It is 0.1-100 mass times with respect to a dinitro compound. Preferably it is 0.5-30 mass times, More preferably, it is 1-10 mass times.
Although reaction temperature is not specifically limited, It is the range from -100 degreeC to the boiling point of the solvent to be used, Preferably, it is -50-150 degreeC. The reaction time is usually 0.05 to 350 hours, preferably 0.5 to 100 hours.

  EXAMPLES The present invention will be specifically described below with reference to examples and the like, but the present invention is not limited to these examples. In addition, the abbreviations of the compounds and the methods for property evaluation are as follows.

<Organic solvent>
NMP: N-methyl-2-pyrrolidone, GBL: γ-butyrolactone BCS: butyl cellosolve, Pd / C: palladium carbon DMSO: dimethyl sulfoxide, THF: tetrahydrofuran <additive>
LS-4668: 3-glycidoxypropyltriethoxysilane

(Measurement of 1H-NMR)
Apparatus: Varian NMR system 400NB (400 MHz) (manufactured by Varian), and JMTC-500 / 54 / SS (500 MHz) (manufactured by JEOL)
Measurement solvent: CDCl3 (deuterated chloroform), DMSO-d6 (deuterated dimethyl sulfoxide)
Reference materials: TMS (tetramethylsilane) (δ: 0.0 ppm, 1H) and CDCl 3 (δ: 77.0 ppm, 13C)

<Synthesis of diamine compound (DA-1)>

A 2-L (liter) four-necked flask was charged with 2-bromo-4-nitrophenylacetophenone (100 g, 410 mmol), thiourea (31.2 g, 410 mmol), and NMP (600 g), and the mixture was heated to 60 ° C. with stirring with a feather. The temperature was raised, and triethylamine (83.0 g, 820 mmol) was added dropwise over 10 minutes, followed by stirring for 1 hour. After confirming the completion of the reaction by HPLC (high performance liquid chromatography), methanol (1500 g) was added, and the mixture was cooled to 5 ° C. and stirred for 1 hour. The precipitated crystals were filtered under reduced pressure, washed with 2-propanol (200 g), and dried to obtain powder crystals (1) (yield 87 g, yield 96%).
1H-NMR (CDCl3, δppm); 8.25-8.20 (2H, m), 8.10-8.03 (2H, m), 7.42 (1H, s), 7.25 (1H, s)

Compound (1) (50 g, 226 mmol), 4-fluoronitrobenzene (38.3 g, 271 mmol), cesium carbonate (73.6 g, 226 mmol), DMSO (500 g), and water (10 g) are charged into a 1 L four-necked flask. The temperature was raised to 60 ° C. with wing stirring, and the mixture was stirred for 12 hours. Thereafter, cesium carbonate (73.6 g, 226 mmol) was further added, and the mixture was stirred for 12 hours. The resulting reaction solution was filtered to remove the salt, methanol (500 g) -water (500 g) was added dropwise, and the mixture was cooled to 5 ° C. and stirred for 1 hour. The precipitated crystals were filtered under reduced pressure, washed with repulp 3 times with methanol (500 g), and then dried to obtain powder crystals (2) (yield 42 g, yield 54%).
1H-NMR (DMSO-d6, δ ppm); 11.2 (1H, s), 8.30-8.22 (6H, m), 7.98-7.94 (3H, m)

A mixture of compound (2) (20 g, 29.2 mmol), 5 mass% Pd / C (50% hydrous type), and THF (200 g) was stirred at 60 ° C. for 12 hours under hydrogen pressure. After completion of the reaction, the catalyst was filtered, concentrated, and slurry washed with toluene (200 g). The precipitated crystals were filtered under reduced pressure, washed with toluene (40 g), and then dried to obtain powder crystals DA-1 (yield 16 g, yield 91%).
1H-NMR (DMSO-d6, δ ppm); 9.55 (1H, s), 7.55-7.50 (2H, m), 7.28-7.25 (2H, m), 6.72 (1H, s), 6.58-6.45 (m-4H ), 5.20 (1H, s), 4.82 (2H, s)

<Synthesis of Compound (DA-3)>

  As a raw material for synthesis, 2-amino-6-nitrobenzothiazole was directly used as a product of Tokyo Chemical Industry Co., Ltd. A mixture of 2-amino-6-nitrobenzothiazole (97.6 g, 0.50 mol), 5 wt% Pd / C (50% hydrous type), and ethanol (3000 g) was heated at 60 ° C. under hydrogen pressure conditions. Stir for 12 hours. After completion of the reaction, the catalyst was filtered and concentrated, and the resulting crystals were slurry washed with 2-propanol (200 g). The crystals were filtered under reduced pressure, washed with 2-propanol (40 g), and dried to obtain powdered crystals DA-3 (yield 44.8 g, yield 54%).

<Synthesis of polymer>
[Synthesis Example 1]
DA-1 (2.26 g, 8.0 mmol) was added to a 50 ml four-necked flask equipped with a stirrer and a nitrogen introduction tube, and then 26.0 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring this diamine solution, CA-2 (1.57 g, 8.0 mmol) was added, 6.5 g of NMP was added, and the mixture was further stirred for 12 hours at 25 ° C. % Polyamic acid solution (PAA-1) was obtained. The viscosity of this polyamic acid solution was 300 mPa · s.

[Synthesis Example 2]
DA-1 (1.98 g, 7.0 mmol) was added to a 50 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube, and then 23.4 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring the diamine solution, CA-1 (1.39 g, 6.4 mmol) was added, 5.9 g of NMP was added, and the mixture was further stirred for 12 hours at 50 ° C. % Polyamic acid solution (PAA-2) was obtained. The viscosity of this polyamic acid solution was 275 mPa · s.

[Synthesis Example 3]
After DA-1 (1.81 g, 6.4 mmol) and DA-4 (0.39 g, 1.6 mmol) were added to a 50 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube, 20.4 g of NMP was added. In addition, the mixture was stirred and dissolved while feeding nitrogen. While stirring this diamine solution, CA-2 (0.64 g, 3.3 mmol) was added, 2.1 g of NMP was added, and the mixture was stirred at 25 ° C. for 1 hour. Thereafter, (0.87 g, 4.0 mmol) of CA-1 was added, 3.0 g of NMP was added, and the mixture was further stirred for 12 hours under the condition of 50 ° C., so that a polyamic acid solution having a resin solid content concentration of 15 mass% (PAA-3) was obtained. The viscosity of this polyamic acid solution was 593 mPa · s.

[Synthesis Example 4]
8.3 g of the polyamic acid solution (PAA-1) obtained in Synthesis Example 1 was collected, and while stirring, NMP solution containing 6.5 g of NMP, 5.2 g of BCS, and 1% by weight of LS-4668 was 0. And 8 g were further stirred at room temperature for 2 hours to obtain a liquid crystal alignment agent (Q-1).

[Synthesis Example 5]
10.2 g of the polyamic acid solution (PAA-2) obtained in Synthesis Example 2 was collected, and 1 NMP solution containing 5.8 g of NMP, 5.7 g of BCS, and 1% by weight of LS-4668 was stirred while stirring. 0.0 g was added, and the mixture was further stirred at room temperature for 2 hours to obtain a liquid crystal alignment agent (Q-2).

[Synthesis Example 6]
7.1 g of the polyamic acid solution (PAA-3) obtained in Synthesis Example 3 was taken, and while stirring, 4.1 g of NMP, 4.9 g of BCS, 7.42 g of GBL, and 1 weight of LS-4668 % NMP solution was added, and the mixture was further stirred at room temperature for 2 hours to obtain a liquid crystal alignment agent (Q-3).

[Comparative Synthesis Example 1]
DA-2 (1.39 g, 7.0 mmol) was added to a 50 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube, and then 19.4 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring the diamine solution, CA-2 (1.15 g, 5.9 mmol) was added, 4.2 g of NMP was added, and the mixture was further stirred for 12 hours at 25 ° C. % Polyamic acid solution (PAA-4) was obtained. The viscosity of this polyamic acid solution was 280 mPa · s.

[Comparative Synthesis Example 2]
DA-4 (4.89 g, 20.0 mmol) was added to a 100 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube, and then 59.1 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring this diamine solution, CA-2 (1.57 g, 8.0 mmol), CA-1 (2.18 g, 10.0 mmol) were added, and 14.8 g of NMP was added. The mixture was stirred for 12 hours to obtain a polyamic acid solution (PAA-5) having a resin solid content concentration of 12% by mass. The viscosity of this polyamic acid solution was 270 mPa · s.

[Comparative Synthesis Example 3]
DA-3 (1.32 g, 8.0 mmol) was added to a 50 ml four-necked flask equipped with a stirrer and a nitrogen inlet tube, and then 24.6 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring this diamine solution, CA-1 (1.69 g, 7.8 mmol) was added, 6.2 g of NMP was added, and then the mixture was further stirred at 25 ° C. for 12 hours, whereby the resin solid content concentration was 10 mass. % Polyamic acid solution (PAA-6) was obtained. The viscosity of this polyamic acid solution was 150 mPa · s.

[Comparative Synthesis Example 4]
10.8 g of the polyamic acid solution (PAA-4) obtained in Comparative Synthesis Example 1 was collected, and an NMP solution containing 6.8 g of NMP, 6.2 g of BCS, and 1% by weight of LS-4668 was stirred while stirring. 1.1 g was added and further stirred at room temperature for 2 hours to obtain a liquid crystal alignment agent (Q-4).

[Comparative Synthesis Example 5]
7.3 g of the polyamic acid solution (PAA-5) obtained in Comparative Synthesis Example 2 was collected, and an NMP solution containing 6.8 g of NMP, 4.7 g of BCS, and 1% by weight of LS-4668 was stirred. 0.9 g was added and further stirred at room temperature for 2 hours to obtain a liquid crystal alignment agent (Q-5).

[Comparative Synthesis Example 6]
10.7 g of the polyamic acid solution (PAA-6) obtained in Comparative Synthesis Example 3 was collected, and while stirring, an NMP solution containing 5.5 g of NMP, 5.0 g of BCS, and 1% by weight of LS-4668 was obtained. 1.1 g was added, and further stirred at room temperature for 2 hours to obtain a liquid crystal alignment agent (Q-6).

<Molecular weight measurement of polyimide precursor and imidized polymer>
The molecular weights of the polyimide precursor and the imidized polymer are the room temperature gel permeation chromatography (GPC) apparatus (GPC-101) (made by Showa Denko KK) and the columns (KD-803, KD-805) (made by Shodex). And measured as follows.
Column temperature: 50 ° C
Eluent: N, N′-dimethylformamide (as additives, lithium bromide-hydrate (LiBr · H 2 O) is 30 mmol / L (liter), phosphoric acid / anhydrous crystal (o-phosphoric acid) is 30 mmol / L , Tetrahydrofuran (THF) at 10 ml / L)
Flow rate: 1.0 ml / min Standard sample for preparing a calibration curve: TSK standard polyethylene oxide (molecular weight; about 900,000, 150,000, 100,000, and 30,000) (manufactured by Tosoh Corporation) and polyethylene glycol (molecular weight; (About 12,000, 4,000, and 1,000) (manufactured by Polymer Laboratory).

<Viscosity measurement>
The viscosity of the polyamic acid solution was measured at 25 ° C. using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample amount of 1.1 mL and cone rotor TE-1 (1 ° 34 ′, R24). did.

<Rubbing resistance evaluation>
The obtained liquid crystal aligning agent is filtered through a 1.0 μm filter, spin-coated on a glass substrate with a transparent electrode, dried on an 80 ° C. hot plate for 5 minutes, and then baked at 230 ° C. for 20 minutes. A polyimide film having a thickness of 100 nm was obtained. This polyimide film was rubbed once with a rayon cloth (roll diameter 120 mm, rotation speed 1000 rpm, moving speed 20 mm / sec, pushing amount 0.4 mm). The surface of the film was observed using a confocal laser microscope, and was scraped at a magnification of 100 times to observe the presence of scraps and the presence of scratches. The evaluation was defined as “good” when the scraped scraps and scratches were hardly seen, and defined as “bad” when the scraped scraps and rubbing scratches were observed.

<Production of liquid crystal display element>
First, a substrate with electrodes was prepared. The substrate is a glass substrate having a size of 30 mm × 35 mm and a thickness of 0.7 mm. On the substrate, an IZO electrode having a solid pattern constituting a counter electrode as a first layer is formed. On the counter electrode of the first layer, a SiN (silicon nitride) film formed by the CVD method is formed as the second layer. The second layer SiN film has a thickness of 500 nm and functions as an interlayer insulating film. On the second SiN film, a comb-like pixel electrode formed by patterning an IZO film as the third layer is arranged to form two pixels, a first pixel and a second pixel. ing. The size of each pixel is 10 mm long and about 5 mm wide. At this time, the first-layer counter electrode and the third-layer pixel electrode are electrically insulated by the action of the second-layer SiN film.

  The pixel electrode of the third layer has a comb-like shape configured by arranging a plurality of dog-shaped electrode elements whose central portion is bent, as in the drawing described in Japanese Patent Application Laid-Open No. 2014-77845. . The width in the short direction of each electrode element is 3 μm, and the distance between the electrode elements is 6 μm. Since the pixel electrode forming each pixel is formed by arranging a plurality of bent-shaped electrode elements in the central portion, the shape of each pixel is not rectangular, but in the central portion like the electrode elements. It has a shape that bends and resembles a bold “Koji”. Each pixel is divided into upper and lower portions with a central bent portion as a boundary, and has a first region on the upper side of the bent portion and a second region on the lower side.

  When the first region and the second region of each pixel are compared, the formation directions of the electrode elements of the pixel electrodes constituting them are different. That is, when the rubbing direction of the liquid crystal alignment film described later is used as a reference, the electrode element of the pixel electrode is formed to form an angle of + 10 ° (clockwise) in the first region of the pixel, and the pixel in the second region of the pixel. The electrode element of the electrode is formed so as to form an angle of −10 ° (clockwise). That is, in the first region and the second region of each pixel, the directions of the rotation operation (in-plane switching) of the liquid crystal induced by the voltage application between the pixel electrode and the counter electrode are mutually in the substrate plane. It is comprised so that it may become a reverse direction.

  Next, after the obtained liquid crystal aligning agent is filtered through a 1.0 μm filter, an ITO film is formed on the back surface as the prepared substrate with electrodes and a counter substrate, and a columnar spacer having a height of 4 μm. Each of the glass substrates having was spin-coated. Subsequently, after drying for 5 minutes on an 80 degreeC hotplate, it baked at 230 degreeC for 20 minutes, and obtained the polyimide film on each board | substrate as a 60 nm-thick coating film. The polyimide film is rubbed with a rayon cloth in a predetermined rubbing direction (roll diameter 120 mm, rotation speed 500 rpm, moving speed 30 mm / sec, pushing amount 0.3 mm), and then irradiated with ultrasonic waves in pure water for 1 minute. And dried at 80 ° C. for 10 minutes.

  Then, using the two types of substrates with the liquid crystal alignment film, the rubbing directions are combined so that they are antiparallel, the periphery is sealed leaving the liquid crystal injection port, and an empty cell with a cell gap of 3.8 μm is formed. Produced. After liquid crystal (MLC-3019, manufactured by Merck & Co., Inc.) was vacuum-injected into this empty cell at room temperature, the injection port was sealed to obtain an anti-parallel alignment liquid crystal cell. The obtained liquid crystal cell constitutes an FFS mode liquid crystal display element. Thereafter, the obtained liquid crystal cell was heated at 120 ° C. for 1 hour and allowed to stand overnight before being used for each evaluation.

<Evaluation of afterimage erasing time>
The afterimage was evaluated using the following optical system and the like. The prepared liquid crystal cell is installed between two polarizing plates arranged so that the polarization axes are orthogonal to each other, and the LED backlight is turned on with no voltage applied, so that the brightness of transmitted light is minimized. The arrangement angle of the liquid crystal cell was adjusted.

Next, a VT curve (voltage-transmittance curve) was measured while applying an AC voltage with a frequency of 30 Hz to the liquid crystal cell, and an AC voltage with a relative transmittance of 23% was calculated as a drive voltage.
In the afterimage evaluation, a DC voltage of 1 V was applied at the same time while driving the liquid crystal cell by applying an AC voltage of 30 Hz with a relative transmittance of 23%, and the liquid crystal cell was driven for 30 minutes. Thereafter, the applied DC voltage value was set to 0 V, and only the application of the DC voltage was stopped, and the device was further driven for 15 minutes in this state.

  In the afterimage evaluation, the time during which the relative transmittance was reduced to 30% or less by the time 60 minutes elapsed from the start of application of the DC voltage was quantified. When it took 60 minutes or more before the relative transmittance decreased to 30% or less, it was defined as an afterimage erasure impossible. And the afterimage evaluation according to the method mentioned above was performed on the temperature conditions of the state whose temperature of a liquid crystal cell is 23 degreeC.

<Stability evaluation of liquid crystal alignment>
Using this liquid crystal cell, an AC voltage of 10 VPP was applied at a frequency of 30 Hz in a constant temperature environment of 60 ° C. for 168 hours. Thereafter, the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited and left as it was at room temperature for one day.
After leaving, the liquid crystal cell is placed between two polarizing plates arranged so that the polarization axes are orthogonal, and the backlight is turned on with no voltage applied so that the brightness of the transmitted light is minimized. The arrangement angle of the liquid crystal cell was adjusted. Then, the rotation angle when the liquid crystal cell was rotated from the angle at which the second region of the first pixel became darkest to the angle at which the first region became darkest was calculated as an angle Δ. Similarly, for the second pixel, the second area was compared with the first area, and a similar angle Δ was calculated. Then, the average value of the angle Δ values of the first pixel and the second pixel was calculated as the angle Δ of the liquid crystal cell. The lower the value of the angle Δ of the liquid crystal cell, the better, and the higher the value, the poorer the evaluation.

<Examples 1-3>
Using the liquid crystal aligning agents obtained in Synthesis Examples 4 to 6, (Q-1 to Q-3) were subjected to rubbing resistance evaluation, evaluation of afterimage erasing time, and stability evaluation of liquid crystal alignment. The results are shown in Table 1.

<Comparative Examples 1-3>
Using the liquid crystal aligning agents (Q-4 to Q-6) obtained in Comparative Synthesis Examples 4 to 6, each evaluation of rubbing resistance, afterimage erasing time, and stability of liquid crystal alignment was performed. The results are shown in Table 1.

  From the above results, the liquid crystal aligning agent of the present invention can provide a liquid crystal aligning film that can simultaneously realize characteristics such as excellent rubbing resistance, fast relaxation of accumulated charges, and high stability of liquid crystal alignment. I understand that.

The liquid crystal aligning agent of this invention is widely used for formation of the liquid crystal aligning film in the liquid crystal display element used for display parts, such as a smart phone, a mobile telephone, a personal computer, and a television, especially a horizontal electric field type liquid crystal display element.
It should be noted that the entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2015-203278 filed on October 14, 2015 are cited herein as disclosure of the specification of the present invention. Incorporate.

Claims (10)

The liquid crystal aligning agent characterized by including the polymer which has a structure represented by following formula (1) in a principal chain.

(R ₁ is hydrogen or a monovalent organic group. Ar is a phenyl group or a naphthalene group which may have a substituent. * Indicates a site bonded to another group.)   The polymer having a structure represented by the formula (1) in the main chain is at least one polymer selected from the group consisting of a polyimide precursor and a polyimide obtained by imidizing the polyimide precursor. Liquid crystal aligning agent. 3. The polymer according to claim 1, wherein the polymer is a polyimide precursor containing a structural unit represented by the following formula (2), and at least one polymer obtained by imidizing the polyimide precursor. Liquid crystal aligning agent.

(In Formula (2), X ₁ is a tetravalent organic group. Y ₁ is a divalent organic group containing the structure of Formula (1) in the main chain direction. R ₂ is a hydrogen atom or a carbon number of 1). ˜5 alkyl groups.) In the formula (2), a liquid crystal aligning agent of claim 3 having the structure Y ₁ is represented by the following formula (3).

(R ₁ is hydrogen or a monovalent organic group. Ar is phenyl or naphthalene which may have a substituent. R ₃ is a single bond or a phenyl group which may have a substituent. * Represents a site bonded to —NH—.) The liquid crystal aligning agent according to claim 4, wherein the formula (3) is any one of the following formulas (3-1) to (3-7).

The liquid crystal aligning agent in Claims 3-5 in which the polyimide precursor containing the structural unit represented by said Formula (2) contains the structural unit represented by following formula (5).

(In Formula (5), X ₂ is a tetravalent organic group derived from a tetracarboxylic acid derivative. Y ₂ is a divalent derived from a diamine that does not include the structure of Y 1 in Formula (1) in the main chain direction). R ₂ and R ₄ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)   The liquid crystal aligning film obtained from the liquid crystal aligning agent of any one of Claims 1-6.   A liquid crystal display device comprising the liquid crystal alignment film of claim 7.   The liquid crystal display element according to claim 8, wherein the liquid crystal display element is of a horizontal electric field drive system. Diamine represented by following formula (4).

(R ₁ is hydrogen or a monovalent organic group. Ar is phenyl or naphthalene which may have a substituent. R ₃ is a single bond or a phenyl group which may have a substituent. Represents.)