JP6897324B2 - Liquid crystal alignment agent, liquid crystal alignment film and its manufacturing method, and liquid crystal element - Google Patents

Description

The present invention relates to a liquid crystal aligning agent, a liquid crystal alignment film and a method of manufacturing the same, and relates to a liquid crystal element.

Liquid crystal elements are widely used in televisions, mobile devices, various monitors, and the like. In the liquid crystal element, the orientation of the liquid crystal molecules in the liquid crystal cell is controlled by the liquid crystal alignment film which is an organic film formed on the substrate. Conventionally, as a method for obtaining an organic film having a liquid crystal orientation regulating force, a method of rubbing an organic film formed by using a polymer composition, a method of obliquely depositing silicon oxide, and a monomolecular film having a long-chain alkyl group are used. A method of forming a photosensitive organic film, a method of irradiating a photosensitive organic film with light (photoalignment method), and the like are known.

The rubbing method is generally used because it is simple and has good orientation of liquid crystal molecules. Further, in recent years, the photo-alignment method can impart uniform liquid crystal orientation to a photosensitive organic film while suppressing the generation of static electricity and dust, and can also precisely control the liquid crystal orientation direction. Various studies are underway (see, for example, Patent Document 1).

In recent years, liquid crystal elements have been applied to a wide range of devices and applications from large-screen liquid crystal televisions to small display devices such as smartphones and tablet PCs, and further improvement in performance is required for liquid crystal elements. .. Against this background, further improvement of the display quality of liquid crystal elements has become more important than before, and various liquid crystal alignment agents have been proposed to realize this (for example, Patent Documents 2 and 2). 4).

Patent Documents 2 and 3 describe a (thio) urea bond, a spacer portion, and a linking group for the purpose of obtaining a liquid crystal alignment film (excellent in rubbing resistance) with less scratching or scratching on the film surface during rubbing treatment. And a polyimide precursor obtained by using a diamine having a specific structure composed of two aminophenyl structures or a liquid crystal alignment agent containing a polyimide is disclosed. Patent Document 4 describes a liquid crystal that improves the storage stability of the liquid crystal aligning agent and whitens the polymer component, has good initial characteristics, and does not easily decrease the voltage retention rate even after being exposed to light for a long time. It is disclosed that a plurality of different types of specific polyimide precursors or polyimides are used in combination in order to obtain a display element.

International Publication No. 2012/176822 Japanese Patent No. 5333454 Japanese Patent No. 5713010 International Publication No. 2015/046373

Conventional liquid crystal alignment agents with good rubbing resistance tend to generate afterimages (hereinafter, also referred to as “AC afterimages”) due to the application of AC voltage, and the voltage retention rate decreases, that is, AC afterimage characteristics and Often there is a trade-off with voltage retention. This AC afterimage is an afterimage that occurs because the direction of initial orientation deviates from the direction at the time of manufacture of the liquid crystal element due to long-term driving of the liquid crystal element. Further, in the case of the photo-alignment method, the orientation-regulating force of the liquid crystal molecules is not sufficient as compared with the rubbing method, and an AC afterimage tends to occur. In order to meet the demand for higher performance in recent years, as a liquid crystal aligning agent, in the case of the rubbing method, both the improvement of the rubbing resistance of the film and the improvement of the AC afterimage characteristic and the voltage retention rate of the liquid crystal element are compatible. In the case of the photoalignment method, there is a demand for a liquid crystal aligning agent which has good photoreactivity of the film, can sufficiently reduce the AC afterimage, and can improve the voltage retention rate.

The present invention has been made in view of the above circumstances, and obtains a liquid crystal element having high photoreactivity or rubbing resistance of the obtained coating film and having improved liquid crystal orientation, AC afterimage characteristics and voltage holding characteristics in a well-balanced manner. One object is to provide a liquid crystal alignment agent capable of providing a liquid crystal alignment agent.

The present invention employs the following means to solve the above problems.

（式（１）及び式（２）中、Ｘ^１は４価の有機基であり、Ｘ^２は、下記式（３）で表される２価の有機基である。Ｒ^１及びＲ^２は、それぞれ独立して、水素原子又は炭素数１〜６の１価の有機基である。）

（式（３）中、Ａ^１及びＡ^２は、それぞれ独立して２価の芳香環基である。ただし、Ａ^１及びＡ^２の少なくとも一方は２価の窒素含有複素環基である。Ｒ^３及びＲ^５は、それぞれ独立して炭素数１〜１０の２価の脂肪族炭化水素基であり、Ｒ^４は炭素数１〜１０の２価の脂肪族炭化水素基又は当該脂肪族炭化水素基の炭素−炭素結合間に、酸素原子、硫黄原子、「−ＣＯＯ−」、「−ＯＣＯ−」、「−Ｓｉ（Ｒ^２１Ｒ^２２）−」又は「−Ｓｉ（Ｒ^２１Ｒ^２２）−Ｏ−Ｓｉ（Ｒ^２３Ｒ^２４）−」（Ｒ^２１〜Ｒ^２４は、それぞれ独立に水素原子又は炭素数１〜６の脂肪族炭化水素基である。）を有する２価の基である。Ｙ^１及びＹ^２は、それぞれ独立して、単結合、酸素原子、硫黄原子、「−ＣＯＯ−」、「−ＯＣＯ−」、「−ＮＲ^６−」、「−ＮＲ^６−ＣＯ−」又は「−ＣＯ−ＮＲ^６−」（Ｒ^６は、水素原子又は１価の有機基であり、隣接するＲ^３又はＲ^５に結合して環構造を形成していてもよい。）である。Ｚ^１及びＺ^２は、それぞれ独立して下記式（４）〜式（６）のそれぞれで表される基のいずれかである。ｎは０又は１である。「＊」は結合手を示す。）

（式（４）中、Ｒ^７は水素原子又は１価の有機基であり、Ｂ^１は、「−ＮＲ^１４−」、「＊^１−ＣＯ−ＮＲ^１４−」、酸素原子、「＊^１−ＣＯ−Ｏ−」、「−ＮＲ^１４−ＣＯ−ＮＲ^１４−」又は「＊^１−ＮＲ^１４−ＣＯ−Ｏ−」（Ｒ^１４は、水素原子又は１価の有機基であり、「＊^１」は、カルボニル基との結合手を表す。）である。式（５）中、Ｒ^８及びＲ^９は、それぞれ独立して水素原子又は１価の有機基である。式（６）中、Ｒ^１０〜Ｒ^１３は、それぞれ独立して水素原子又は１価の有機基である。「＊」は結合手を示す。） <1> A liquid crystal alignment agent containing a polymer (P) having at least one selected from the group consisting of a partial structure represented by the following formula (1) and a partial structure represented by the following formula (2).

(In the formulas (1) and (2), X ¹ is a tetravalent organic group, X ² is a divalent organic group represented by the following formula (3), and R ^{1 and R 2} are divalent organic groups. , Each independently is a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms.)

(In the formula (3), A ¹ and A ² are independently divalent aromatic ring groups, respectively. However, ^{at least one of A 1} and A ² is a divalent nitrogen-containing heterocyclic group R. ³ and R ⁵ are independently divalent aliphatic hydrocarbon groups ^{having 1 to 10 carbon atoms, and R 4} is a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms or the aliphatic hydrocarbon group. carbon groups - between carbon bond, an oxygen atom, a sulfur atom, "- COO -", "- OCO -", ^{"- Si (R 21 R 22)} - " or ^{"-Si (R 21 R} 22) -O -Si (R ²³ R ²⁴ )-"(R ^{21 to} R ²⁴ are each independently a hydrogen atom or an aliphatic hydrocarbon group having 1 to 6 carbon atoms). Y ¹ And Y ² are independently single-bonded, oxygen atom, sulfur atom, "-COO-", "-OCO-", "-NR ^6- ", "-NR ^6- CO-" or "-CO". -NR ^6- "(R ⁶ is a hydrogen atom or a monovalent organic group, which ^{may be bonded to an adjacent R 3} or R ⁵ to form a ring structure). Z ¹ and Z. ² is any of the groups independently represented by the following formulas (4) to (6). N is 0 or 1. “*” Indicates a bond.)

(In formula (4), ^{R 7} is a hydrogen atom or a monovalent organic group, ^{B 1} is "- ^{NR 14} -", ^"* 1 ^{-CO-NR 14} -", an oxygen atom, ^{"* 1} - CO-O -, "" ^{- NR 14} -CO-NR 14 ^- "or" ^* 1 ^-NR 14 -CO-O - ^{"(R 14} is a hydrogen atom or a monovalent organic group," ^{* 1} " Represents a bond with a carbonyl group.) In formula (5), R ⁸ and R ⁹ are independently hydrogen atoms or monovalent organic groups. In formula (6), R ^{10 to} R ¹³ are independently hydrogen atoms or monovalent organic groups. “*” Indicates a bond.)

（式（１２）中、Ａ^１、Ａ^２、Ｒ^３〜Ｒ、Ｙ^１、Ｙ^２、Ｚ^１、Ｚ^２及びｎはそれぞれ、上記式（３）中のＡ^１、Ａ^２、Ｒ^３〜Ｒ^５、Ｙ^１、Ｙ^２、Ｚ^１、Ｚ^２及びｎと同義である。） <2> A liquid crystal alignment film formed by using the liquid crystal alignment agent of <1> above.
<3> A method for producing a liquid crystal alignment film, which comprises a photoalignment step of forming a coating film using the liquid crystal alignment agent of <1> above and subjecting the coating film to a light irradiation treatment to impart a liquid crystal alignment ability.
<4> A liquid crystal element provided with the liquid crystal alignment film of <2> above.
<5> A polymer having at least one selected from the group consisting of the partial structure represented by the above formula (1) and the partial structure represented by the above formula (2).
<6> A diamine represented by the following formula (12).

(In formula (12), A ¹ , A ² , R ^{3 to} R, Y ¹ , Y ² , Z ¹ , Z ^{2 and n are A 1} , A ² , R ³ to N in the above formula (3), respectively. It is synonymous with R ⁵ , Y ¹ , Y ² , Z ¹ , Z ^{2 and n.)}

According to the above liquid crystal alignment agent, a coating film having good photoreactivity or rubbing resistance can be obtained. Further, it is possible to obtain a liquid crystal element having improved liquid crystal orientation, AC afterimage characteristics and voltage holding characteristics in a well-balanced manner.

Hereinafter, the components to be blended in the liquid crystal alignment agent of the present disclosure and other components to be optionally blended will be described.

≪Polymer (P) ≫
The liquid crystal alignment agent of the present disclosure contains a polymer (P) having at least one selected from the group consisting of the partial structure represented by the above formula (1) and the partial structure represented by the above formula (2). In the above formulas (1) and (2), X ¹ is a tetravalent organic group derived from a tetracarboxylic acid derivative. In addition, in this specification, "tetracarboxylic acid derivative" means containing tetracarboxylic dianhydride, tetracarboxylic acid diester and tetracarboxylic acid diester dihalide.

When a liquid crystal alignment film is obtained by photo-alignment treatment, X ¹ is preferably a tetravalent organic group having a cyclobutane ring structure. The cyclobutane ring structure preferably has at least one substituent on the ring portion of the cyclobutane ring. Examples of the substituent contained in the cyclobutane ring include a halogen atom, an alkyl group, an alkyl halide group, an alkoxy group, an alkenyl group, an alkynyl group and the like. The number of substituents is not particularly limited, but is preferably 1 to 4.

（式（１１）中、Ｒ^３１〜Ｒ^３３は、それぞれ独立して、水素原子、ハロゲン原子、炭素数１〜６のアルキル基、炭素数１〜６のハロゲン化アルキル基、炭素数１〜６のアルコキシ基、炭素数１〜６のチオアルキル基、炭素数２〜６のアルケニル基、炭素数２〜６のアルキニル基、又は「−ＣＯＲ^３０」（Ｒ^３０は、炭素数１〜６のアルキル基、フッ素含有アルキル基、アルコキシ基又はフッ素含有アルコキシ基である。）である。Ｒ^３４は、ハロゲン原子、炭素数１〜６のアルキル基、炭素数１〜６のハロゲン化アルキル基、炭素数１〜６のアルコキシ基、炭素数１〜６のチオアルキル基、炭素数２〜６のアルケニル基、炭素数２〜６のアルキニル基、又は「−ＣＯＲ^３０」である。ただし、Ｒ^３１〜Ｒ^３４のうち隣接する基同士が結合して環構造を形成していてもよい。「＊」は結合手を示す。） When X ¹ is a tetravalent organic group having a cyclobutane ring structure, it is preferably a group represented by the following formula (11).

(In the formula (11), R ^{31 to} R ³³ are independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkyl halide group having 1 to 6 carbon atoms, and 1 to 6 carbon atoms, respectively. Alkoxy group, thioalkyl group having 1 to 6 carbon atoms, alkenyl group having 2 to 6 carbon atoms, alkynyl group having 2 to 6 carbon atoms, or "-COR ³⁰ " (R ³⁰ is an alkyl group having 1 to 6 carbon atoms). , Fluorine-containing alkyl group, alkoxy group or fluorine-containing alkoxy group.) R ³⁴ is a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkyl halide group having 1 to 6 carbon atoms, and 1 carbon atom. Alkoxy groups of ~ 6; thioalkyl groups of 1-6 carbon atoms, alkenyl groups of 2-6 carbon atoms, alkynyl groups of 2-6 carbon atoms, or "-COR ³⁰ ", but of R ^31- R ³⁴ . Adjacent groups may be bonded to each other to form a ring structure. “*” Indicates a bond.)

In the above formulas (1) and (2), X ² is a divalent organic group represented by the above formula (3). In the above formula (3), A ¹ and A ² are independently divalent aromatic ring groups. Here, the "aromatic ring group" in the present specification is a group obtained by removing two hydrogen atoms from the ring portion of a substituted or unsubstituted aromatic ring. Examples of the aromatic ring include aromatic hydrocarbon rings such as benzene ring, naphthalene ring, and anthracene ring; nitrogen-containing aromatic heterocycles such as pyridine ring, pyrazine ring, pyrimidine ring, and pyridazine ring; and sulfur-containing aroma such as thiophene ring. Group heterocycles, etc. may be mentioned. When the aromatic ring has a substituent, examples of the substituent include an alkyl group having 1 to 6 carbon atoms.
Preferred specific examples of A ¹ and A ² include, for example, groups represented by the following formulas (a-1) to (a-11).

At ^{least one of A 1} and A ² is a divalent group obtained by removing two hydrogen atoms from the ring portion of a substituted or unsubstituted nitrogen-containing aromatic heterocycle (hereinafter, "divalent nitrogen-containing heterocyclic group"). That is.). The heterocycle contained in the divalent nitrogen-containing heterocyclic group is preferably one selected from the group consisting of a pyridine ring, a pyrazine ring, a pyrimidine ring and a pyridazine ring. It is preferable in that the photoreactivity of the polymer can be increased and that a liquid crystal device having less generation of minute bright spots due to decomposition products generated by light irradiation during the photoalignment treatment can be obtained. Both A ¹ and A ² are divalent nitrogen-containing heterocyclic groups. Above all, the ^{nitrogen-containing heterocycle contained in A 1} and A ² is preferably a pyridine ring.

For R ³ and R ⁵ , divalent aliphatic hydrocarbon groups having 1 to 10 carbon atoms include chain hydrocarbon groups and alicyclic hydrocarbon groups. Here, the term "chain hydrocarbon group" as used herein means a linear or branched hydrocarbon group that does not contain a cyclic structure and is composed only of a chain structure. However, the chain hydrocarbon group may be saturated or unsaturated. The "alicyclic hydrocarbon group" means a hydrocarbon group containing only the alicyclic hydrocarbon structure as the ring structure and not containing the aromatic ring structure. However, the alicyclic hydrocarbon group does not have to be composed only of the alicyclic hydrocarbon structure, and includes those having a chain structure as a part thereof. R ³ and R ⁵ are preferably a chain hydrocarbon group, and more preferably a linear hydrocarbon group in that the effect of reducing the AC afterimage can be enhanced. The number of carbon atoms is preferably 2 or more in the production of the liquid crystal alignment film by the photo-alignment method in terms of promoting the reorientation of the molecular chains by heating, and in the production of the liquid crystal alignment film by the rubbing alignment method, the rubbing treatment is performed. It is preferable that the number is 2 or more in terms of promoting the extension of the molecular chain due to the above.

Regarding R ^{4 , the above description of R 3} and R ⁵ is applied to specific examples and preferable examples of divalent aliphatic hydrocarbon groups having 1 to 10 carbon atoms. R ⁴ is carbon divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms (preferably a chain hydrocarbon group) - between carbon bond, an oxygen atom, a sulfur atom, "- COO -", "- OCO -"," ^{-Si (R 21} R ²² )-"or" -Si (R ²¹ R ²² ) -O-Si (R ²³ R ²⁴ )-"(R ^{21 to} R ²⁴ are each independently hydrocarbon atom or It may have an aliphatic hydrocarbon group having 1 to 6 carbon atoms).

Y ¹ and Y ² are independently single bonds, oxygen atoms, sulfur atoms, "-COO-", "-OCO-", "-NR ^6- ", "-NR ^6- CO-" or "-NR 6-CO-". -CO-NR ^6- "(R ⁶ is a hydrogen atom or a monovalent organic group, and ^{may be bonded to an adjacent R 3} or R ⁵ to form a ring structure). Examples of the monovalent organic group of R ⁶ include an alkyl group having 1 to 6 carbon atoms, a protecting group and the like. The protecting group is preferably a group that is desorbed by heat, and examples thereof include a carbamate-based protecting group, an amide-based protecting group, an imide-based protecting group, and a sulfonamide-based protecting group. Of these, the tert-butoxycarbonyl group is preferable as the protecting group in that it has high heat-removability and reduces the residual amount in the film of the deprotected portion.
When R ⁶ is bonded to adjacent R ³ or R ⁵ to form a ring structure, examples of the ring structure include a piperazine ring, a piperidine ring, and the like.

Y ¹ and Y ² are preferably an oxygen atom, a sulfur atom or "-NR ^6- ", and at least one of them is "-NR ^6- " in that a polymer having higher photoreactivity can be obtained. More preferably, ^{both Y 1} and Y ² are "-NR ^6- ". R ⁶ in "-NR ^6- " is preferably an alkyl group having 1 to 6 carbon atoms, preferably an alkyl group having 1 to 3 carbon atoms, from the viewpoint of increasing the photoreactivity of the polymer (P). Is more preferable.

（式（３Ａ）中、Ｒ^３〜Ｒ^５、Ｙ^１、Ｙ^２、Ｚ^１、Ｚ^２及びｎはそれぞれ、上記式（３）と同義である。「＊」は結合手を示す。） From the viewpoint of increasing the photoreactivity of the obtained coating film, Y ¹ and Y ² are oxygen atoms, sulfur atoms or "-NR ^6- ", and Y ¹ and Y ² are A ¹ and A ^2. It is preferable that the nitrogen-containing heterocycle has a carbon atom adjacent to the nitrogen atom in the ring of the nitrogen-containing heterocycle. Particularly preferably, in the above formula (3), the ^{nitrogen-containing heterocycle of A 1} and A ² is a pyridine ring, and ^{the bond site on the pyridine ring of Y 1} and Y ² is relative to the nitrogen atom of the pyridine ring. It is a structure that is in the ortho position and is in the para position with respect to the nitrogen atom in the above formula (1) and the above formula (2) that is bonded to ^{X 2.} Specifically, the group represented by the above formula (3) is preferably a group represented by the following formula (3A).

(In the formula (3A), R ^{3 to} R ⁵ , Y ¹ , Y ² , Z ¹ , Z ² and n are synonymous with the above formula (3). “*” Indicates a bond.)

Z ¹ and Z ² are divalent functional groups having hydrogen bonding properties, and are any of the groups represented by the above formulas (4) to (6). In the above formula (4) to Formula (6), B ¹ is that the rubbing resistance is obtained a better liquid crystal alignment film, and in that the higher the liquid crystal element is a voltage holding ratio obtained, "- NR ¹³ - "or" ^* 1 ^{-CO-NR 13} - "is preferable. The ^{above description of R 6} is applied to specific examples and preferable examples of the monovalent organic groups of ^{R 7 to} R ^13.

（式中、「＊」は結合手であることを示す。） Preferred specific examples of Z ¹ and Z ² include groups represented by the following formulas (z-1) to (z-10), respectively.

(In the formula, "*" indicates a bond.)

Z ¹ and Z ² are preferably groups represented by the above formula (4) in that the rubbing resistance of the obtained coating film and the liquid crystal orientation and electrical characteristics of the liquid crystal element can be further improved. Specifically, the structure represented by the above formula (z-1) or formula (z-2) is particularly preferable.
n is 0 or 1, preferably 0.

The polymer (P) is at least one selected from the group consisting of polyamic acid, polyamic acid ester and polyimide. The polymer (P) is derived from a diamine compound having a partial structure derived from a tetracarboxylic acid derivative and a divalent organic group represented by the above formula (3) (hereinafter, also referred to as "specific diamine"). It has a partial structure. The method for synthesizing the polymer (P) is not particularly limited, and it can be obtained by appropriately combining conventional methods of organic chemistry.

<Polyamic acid>
When the polymer (P) is a polyamic acid, the polyamic acid (hereinafter, also referred to as “polyamic acid (P)”) contains, for example, a tetracarboxylic dianhydride and a diamine compound containing a specific diamine. It can be obtained by reacting.

(Tetracarboxylic dianhydride)
The tetracarboxylic dianhydride used for the synthesis of polyamic acid (P) is not particularly limited, and for example, an aliphatic tetracarboxylic dianhydride, an alicyclic tetracarboxylic dianhydride, or an aromatic tetracarboxylic dianhydride is used. Anhydrous and the like can be mentioned. Specific examples of these include, for example, ethylenediaminetetraacetic acid dianhydride as an aliphatic tetracarboxylic dianhydride;

Examples of the alicyclic tetracarboxylic dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, and a tetracarboxylic dianhydride having a group represented by the above formula (11) (hereinafter, "" (Also referred to as "substituted cyclobutanetetracarboxylic dianhydride"), 2,3,5-tricarboxycyclopentylacetic dianhydride, 5- (2,5-dioxotetracarboxylic dianhydride) -3a,4,5,5. 9b-tetrahydronaphtho [1,2-c] furan-1,3-dione, 5- (2,5-dioxotetrahydrofuran-3-yl) -8-methyl-3a, 4,5,9b-tetrahydronaphtho [ 1,2-c] furan-1,3-dione, 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, 3,5 , 6-Tricarboxy-2-carboxymethyl dianbornene-2: 3,5: 6-dianhydride, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-dianhydride, cyclohexanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, etc.;

Examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 4,4'-(hexafluoroisopropyridene) diphthalic anhydride, p-phenylenebis (trimellitic acid monoester anhydride), and ethylene glycol. Bis (anhydrotrimeritate), 1,3-propylene glycol bis (anhydrotrimeritate), 3,3', 4,4'-benzophenonetetracarboxylic dianhydride, etc .; , Tetracarboxylic dianhydride described in JP-A-2010-97188 can be used.

Substituted cyclobutanetetracarboxylic dianhydride in the synthesis of polyamic acid (P) in that the photoreactivity of the coating film can be increased in combination with a specific diamine when the liquid crystal alignment ability is imparted to the coating film by the photo-alignment method. Can be preferably used. Specific examples of the substituted cyclobutanetetracarboxylic dianhydride include compounds represented by the following formulas (TA-1-1) to (TA-1-6).

When a substituted cyclobutanetetracarboxylic dianhydride is used in the synthesis of polyamic acid (P), the proportion of the substituted cyclobutanetetracarboxylic dianhydride used in the synthesis is such that the photoreactivity of the coating film is sufficiently high. It is preferably 10 mol% or more based on the total amount. It is more preferably 30 mol% or more, still more preferably 50 mol% or more. In the synthesis of the polymer (P), one type of tetracarboxylic dianhydride may be used alone or two or more types may be used in combination.

（式（１２）中、Ａ^１、Ａ^２、Ｒ^３〜Ｒ^５、Ｙ^１、Ｙ^２、Ｚ^１、Ｚ^２及びｎは、それぞれ、上記式（３）中のＡ^１、Ａ^２、Ｒ^３〜Ｒ^５、Ｙ^１、Ｙ^２、Ｚ^１、Ｚ^２及びｎと同義である。） (Diamine compound)
Examples of the specific diamine include compounds represented by the following formula (12).

(In the formula (12), A ¹ , A ² , R ^{3 to} R ⁵ , Y ¹ , Y ² , Z ¹ , Z ^{2 and n are A 1} , A ² , R in the above formula (3), respectively. ^{3 to} R ⁵ , ^{synonymous with Y 1} , Y ² , Z ¹ , Z ² and n)

Specific examples and preferred examples of A ¹ , A ² , R ^{3 to} R ⁵ , Y ¹ , Y ² , Z ¹ , Z ² and n in the above formula (12) are described in the above formula (3), respectively. Applies. Specific examples of the specific diamine include compounds represented by the following formulas (d-1) to (d-22), for example.

As the specific diamine, among these, compounds represented by the above formulas (d-1) to (d-8) are preferable, and the above formulas (d-1), formula (d-2), and formula (d) Compounds represented by each of d-5), formula (d-7) and formula (d-11) are particularly preferable. The specific diamine may be used alone or in combination of two or more.

In the synthesis of the polyamic acid (P), only the specific diamine may be used as the diamine compound, but other diamines other than the specific diamine may be used together with the specific diamine.

The other diamine is not particularly limited as long as it does not have the group represented by the above formula (3), and examples thereof include an aliphatic diamine, an alicyclic diamine, an aromatic diamine, and a diaminoorganosiloxane. Specific examples of these include, for example, metaxylylenediamine, ethylenediamine, 1,3-propanediamine, tetramethylenediamine, hexamethylenediamine and the like as aliphatic diamines; and for example, p-cyclohexanediamine and 4 as alicyclic diamines. , 4'-Methylenebis (cyclohexylamine), etc .;

（式（Ｅ−１）中、Ｘ^I及びＸ^IIは、それぞれ独立に、単結合、−Ｏ−、−ＣＯＯ−又は−ＯＣＯ−であり、Ｒ^Ｉは炭素数１〜３のアルカンジイル基であり、Ｒ^ＩＩは単結合又は炭素数１〜３のアルカンジイル基であり、ａは０又は１であり、ｂは０〜２の整数であり、ｃは１〜２０の整数であり、ｄは０又は１である。ただし、ａ及びｂが同時に０になることはない。）
で表される化合物等の側鎖型ジアミン：
パラフェニレンジアミン、４，４’−ジアミノジフェニルメタン、４，４’−エチレンジアニリン、４，４’−ジアミノジフェニルアミン、４，４’−ジアミノジフェニルスルフィド、４−アミノフェニル−４’−アミノベンゾエート、４，４’−ジアミノアゾベンゼン、３，５−ジアミノ安息香酸、１，２−ビス（４−アミノフェノキシ）エタン、１，５−ビス（４−アミノフェノキシ）ペンタン、Ｎ，Ｎ’−ジ（４−アミノフェニル）−Ｎ，Ｎ’−ジメチルエチレンジアミン、ビス［２−（４−アミノフェニル）エチル］ヘキサン二酸、ビス（４−アミノフェニル）アミン、Ｎ，Ｎ−ビス（４−アミノフェニル）メチルアミン、１，４−ビス（４−アミノフェニル）−ピペラジン、Ｎ，Ｎ’−ビス（４−アミノフェニル）−ベンジジン、２，２’−ジメチル−４，４’−ジアミノビフェニル、２，２’−ビス（トリフルオロメチル）−４，４’−ジアミノビフェニル、４，４’−ジアミノジフェニルエーテル、２，２−ビス［４−（４−アミノフェノキシ）フェニル］プロパン、４，４’−（フェニレンジイソプロピリデン）ビスアニリン、１，４−ビス（４−アミノフェノキシ）ベンゼン、４−（４−アミノフェノキシカルボニル）−１−（４−アミノフェニル）ピペリジン、４，４’−［４，４’−プロパン−１，３−ジイルビス（ピペリジン−１，４−ジイル）］ジアニリン等の非側鎖型ジアミンを；
ジアミノオルガノシロキサンとして、例えば、１，３−ビス（３−アミノプロピル）−テトラメチルジシロキサン等を；それぞれ挙げることができるほか、特開２０１０−９７１８８号公報に記載のジアミン化合物を用いることができる。なお、ポリアミック酸（Ｐ）の合成に際し、その他のジアミンは１種を単独で又は２種以上を組み合わせて使用できる。 Examples of aromatic diamines include dodecanoxidiaminobenzene, hexadecanoxidiaminobenzene, octadecanoxidiaminobenzene, cholestanyloxydiaminobenzene, cholesteryloxydiaminobenzene, cholestanyl diaminobenzoate, cholesteryl diaminobenzoate, and diaminobenzoic acid. Ranostanil, 3,6-bis (4-aminobenzoyloxy) cholesterol, 3,6-bis (4-aminophenoxy) cholesterol, 1,1-bis (4-((aminophenyl) methyl) phenyl) -4-butyl Cyclohexane, 2,5-diamino-N, N-diallylaniline, the following formula (E-1)

(In the formula (E-1), X ^I and X ^II is independently a single bond, -O -, - COO- or a -OCO-, ^{R I} is alkanediyl group having 1 to 3 carbon atoms Yes, R ^II is a single bond or an alkanediyl group with 1-3 carbon atoms, a is 0 or 1, b is an integer 0-2, c is an integer 1-20, d is It is 0 or 1. However, a and b cannot be 0 at the same time.)
Side chain diamines such as compounds represented by:
Paraphenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-ethylenedianiline, 4,4'-diaminodiphenylamine, 4,4'-diaminodiphenylsulfide, 4-aminophenyl-4'-aminobenzoate, 4 , 4'-diaminoazobenzene, 3,5-diaminobenzoic acid, 1,2-bis (4-aminophenoxy) ethane, 1,5-bis (4-aminophenoxy) pentane, N, N'-di (4-aminophenoxy) Aminophenyl) -N, N'-dimethylethylenediamine, bis [2- (4-aminophenyl) ethyl] hexanedioic acid, bis (4-aminophenyl) amine, N, N-bis (4-aminophenyl) methylamine , 1,4-Bis (4-aminophenyl) -piperazin, N, N'-bis (4-aminophenyl) -benzidine, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'- Bis (trifluoromethyl) -4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl ether, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 4,4'-(phenylenediisopropi) Liden) bisaniline, 1,4-bis (4-aminophenoxy) benzene, 4- (4-aminophenoxycarbonyl) -1- (4-aminophenyl) piperidine, 4,4'-[4,4'-propane- 1,3-Diylbis (piperidin-1,4-diyl)] Non-side chain amines such as dianiline;
Examples of the diaminoorganosiloxane include 1,3-bis (3-aminopropyl) -tetramethyldisiloxane; and the diamine compound described in JP-A-2010-97188 can be used. .. In the synthesis of polyamic acid (P), one type of other diamine may be used alone or two or more types may be used in combination.

The ratio of the specific diamine used is preferably 20 mol% or more with respect to the total amount of the diamine compounds used in the synthesis of the polyamic acid (P) from the viewpoint of sufficiently obtaining the effects of the present disclosure. It is more preferably 40 mol% or more, still more preferably 60 mol% or more.

The specific diamine can be obtained by appropriately combining the conventional methods of organic chemistry. As an example, a dinitro intermediate having a nitro group instead of the primary amino group in the above formula (12) is synthesized, and then the nitro group of the obtained dinitro intermediate is aminated using an appropriate reducing system. How to do it.

The method for synthesizing the dinitro intermediate can be appropriately selected depending on the target compound. For example, after reacting an isocyanate compound with an amine compound to obtain a compound represented by "HY ^1- R ^3- (Z ^1- R ⁴ ) _n- Z ^2- R ^{5- Y 2-H".} , A method of reacting the obtained compound with a halogen compound having the structure "-A-NO ₂ " (A is A ¹ or A ² _{); the structure "-RY-A-NO 2} " ( R is R ³ or R ⁵ , and Y is Y ¹ or Y ² ).) A method of reacting an amine compound with carbonyldiimidazole; an amine having the _{structure "-RY-A-NO 2".} Method of reacting a compound with oxalyl chloride; method of reacting _{an amine compound having a structure "-RY-A-NO 2} " with a diisocyanate compound; structure "-R ^3- (Z ^1- R ⁴ ) _n- and the like; ^- Z 2 ^-R 5 and "acid chloride with a method of reacting an amine compound having the structure" -A-NO ₂ ". However, the method for synthesizing the specific diamine is not limited to the above.

(Synthesis of polyamic acid)
The polyamic acid (P) is produced by reacting a tetracarboxylic dianhydride as described above with a diamine compound, if necessary, with a molecular weight regulator (for example, an acid monoanhydride, a monoamine compound, a monoisocyanate compound, etc.). Obtainable. The ratio of the tetracarboxylic dianhydride and the diamine compound used in the synthesis reaction of the polyamic acid (P) is such that the acid dianhydride group of the tetracarboxylic dianhydride is used with respect to 1 equivalent of the amino group of the diamine compound. A ratio of 0.2 to 2 equivalents is preferable.

The synthetic reaction of the polyamic acid (P) is preferably carried out in an organic solvent. The reaction temperature at this time is preferably −20 ° C. to 150 ° C., and the reaction time is preferably 0.1 to 24 hours. Examples of the organic solvent used in the reaction include aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons and the like. Particularly preferred organic solvents are N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide, m-cresol, xylenol. One or more selected from the group consisting of and halogenated phenol is used as a solvent, or one or more of these is mixed with another organic solvent (for example, butyl cellosolve, diethylene glycol diethyl ether, etc.). The amount of the organic solvent used is preferably such that the total amount of the tetracarboxylic dianhydride and the diamine compound is 0.1 to 50% by mass with respect to the total amount of the reaction solution. The reaction solution obtained by dissolving the polyamic acid (P) may be used as it is for the preparation of the liquid crystal alignment agent, or the polyamic acid (P) contained in the reaction solution is isolated and then used for the preparation of the liquid crystal alignment agent. You may.

<Polyamic acid ester>
^{The polyamic acid ester as the polymer (P) has a structural unit in which at least one of R 1} and R ^{2 is} a monovalent organic group having 1 to 6 carbon atoms in the partial structure represented by the above formula (1). It is a polymer having. The polyamic acid ester is, for example, [I] a method of reacting the polyamic acid (P) obtained above with an esterifying agent (for example, methanol, ethanol, N, N-dimethylformamide diethylacetal, etc.), [II]. The tetracarboxylic acid diester and the diamine compound containing the specific diamine are preferably in an organic solvent with a suitable dehydration catalyst (eg 4- (4,6-dimethoxy-1,3,5-triazine-2-yl) -4. -A method of reacting in the presence of methylmorpholinium halide, carbonyl imidazole, phosphorus-based condensing agent, etc., [III] a tetracarboxylic acid diester dihalide and a diamine compound containing a specific diamine, preferably in an organic solvent, By a method of reacting in the presence of an appropriate base (for example, a tertiary amine such as pyridine or triethylamine, or an alkali metal such as sodium hydride, potassium hydride, sodium hydroxide, potassium hydroxide, sodium or potassium), etc. Obtainable.

The tetracarboxylic dianhydride used in [II] above can be obtained by ring-opening the tetracarboxylic dianhydride with alcohols or the like. The tetracarboxylic dianester dihalide used in [III] above can be obtained by reacting the tetracarboxylic dianester obtained as described above with an appropriate chlorinating agent such as thionyl chloride.
The polyamic acid ester may have only an amic acid ester structure, or may be a partial esterified product in which an amic acid structure and an amic acid ester structure coexist. When the polyamic acid ester is obtained as a solution by the above reaction, the solution may be used as it is for the preparation of the liquid crystal alignment agent, and the polyamic acid ester contained in the reaction solution is isolated and then the liquid crystal alignment agent is used. It may be used for preparation.

<Polyimide>
The polyimide as the polymer (P) is a polymer having a partial structure represented by the above formula (2). The polyimide can be obtained, for example, by dehydrating and ring-closing the polyamic acid (P) synthesized as described above to imidize it. The polyimide may be a completely imidized product in which all of the amic acid structure possessed by the precursor polyamic acid (P) is dehydrated and ring-closed, and only a part of the amic acid structure is dehydrated and ring-closed to form an amic acid. It may be a partially imidized product in which the structure and the imide ring structure coexist. The imidization ratio of the polyimide is preferably 40 to 100%, more preferably 60 to 90%. This imidization ratio is expressed as a percentage of the ratio of the number of imide ring structures to the total of the number of amic acid structures and the number of imide ring structures of polyimide. Here, a part of the imide ring may be an isoimide ring.

The dehydration ring closure of the polyamic acid (P) is preferably carried out by dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydration ring closure catalyst to the solution, and heating as necessary. As the dehydrating agent, acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride can be used. The amount of the dehydrating agent used is preferably 0.01 to 20 mol with respect to 1 mol of the amic acid structure of the polyamic acid. As the dehydration ring closure catalyst, for example, tertiary amines such as pyridine, collagen, lutidine, and triethylamine can be used. The amount of the dehydration ring closure catalyst used is preferably 0.01 to 10 mol with respect to 1 mol of the dehydrating agent used. Examples of the organic solvent used include organic solvents exemplified as those used for the synthesis of polyamic acid (P). The reaction temperature of the dehydration ring closure reaction is preferably 0 to 180 ° C., and the reaction time is preferably 1.0 to 120 hours. The reaction solution containing the polyimide thus obtained may be used as it is for the preparation of the liquid crystal alignment agent, or the polyimide may be isolated and then used for the preparation of the liquid crystal alignment agent.

The solution viscosity of the polymer (P) preferably has a solution viscosity of 10 to 800 mPa · s when made into a solution having a concentration of 10% by mass, and has a solution viscosity of 15 to 500 mPa · s. Is more preferable. The solution viscosity (mPa · s) is E for a polymer solution having a concentration of 10% by mass prepared using a good solvent of the polymer (P) (for example, γ-butyrolactone, N-methyl-2-pyrrolidone, etc.). It is a value measured at 25 ° C. using a type rotational viscometer.
The polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) of the polymer (P) is preferably 1,000 to 500,000, more preferably 5,000 to 100,000. Is. The molecular weight distribution (Mw / Mn) represented by the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) measured by GPC is preferably 15 or less, more preferably 10 or less. The polymer (P) contained in the liquid crystal alignment agent may be only one type or a combination of two or more types.

≪Other ingredients≫
The liquid crystal alignment agent of the present disclosure may contain other components other than the polymer (P). Examples of the other component include other polymers having neither the partial structure represented by the above formula (1) nor the partial structure represented by the above formula (2), or at least one epoxy in the molecule. Group-containing compounds, functional silane compounds, antioxidants, metal chelate compounds, curing accelerators, surfactants, fillers, dispersants, photosensitizers, acid generators, base generators, radical generators, etc. Can be mentioned. These blending ratios can be appropriately selected according to each compound as long as the effects of the present disclosure are not impaired.

Other polymers are used for the purpose of suppressing a decrease in the voltage retention rate and for improving the liquid crystal orientation. The main skeleton of other polymers is not particularly limited, but for example, polyamic acid, polyimide, polyamic acid ester, polyorganosiloxane, polyester, cellulose derivative, polyacetal, polystyrene derivative, poly (styrene-phenylmaleimide) derivative, poly (meth). ) Examples thereof include polymers having an acrylate or the like as a main skeleton. The other polymer is preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester and polyimide.

When the liquid crystal alignment agent for photo-alignment treatment is used, the polymer (P) may contain a non-photosensitive polymer, and the other polymer may contain a photosensitive polymer. In this case, it is preferable to contain the polymer (P) in that a liquid crystal element showing a higher voltage retention rate than the case where the polymer (P) is not contained can be obtained.
When other polymers are blended in the liquid crystal alignment agent, the blending ratio is preferably 1 to 95% by mass, more preferably 5 to 90% by mass, and 15 to 15% by mass, based on the total amount of the polymer in the liquid crystal alignment agent. 80% by mass is more preferable.

<Solvent>
The liquid crystal alignment agent of the present disclosure is prepared as a liquid composition in which the polymer (P) and other components used as needed are preferably dispersed or dissolved in a suitable solvent.
Examples of the organic solvent used include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,2-dimethyl-2-imidazolidinone, γ-butyrolactone, γ-butyrolactam, N, N-dimethylformamide. , N, N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, Ethyl glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl Examples thereof include ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisopentyl ether, ethylene carbonate and propylene carbonate. These can be used alone or in admixture of two or more.

The solid content concentration in the liquid crystal alignment agent (the ratio of the total mass of the components other than the solvent of the liquid crystal alignment agent to the total mass of the liquid crystal alignment agent) is appropriately selected in consideration of viscosity, volatility, etc., but is preferable. It is in the range of 1 to 10% by mass. That is, the liquid crystal alignment agent is applied to the surface of the substrate as described later, and is preferably heated to form a coating film that is a liquid crystal alignment film or a coating film that becomes a liquid crystal alignment film. At this time, if the solid content concentration is less than 1% by mass, the film thickness of the coating film becomes too small and it becomes difficult to obtain a good liquid crystal alignment film. On the other hand, when the solid content concentration exceeds 10% by mass, the film thickness of the coating film becomes excessive and it is difficult to obtain a good liquid crystal alignment film, and the viscosity of the liquid crystal alignment agent increases and the coatability deteriorates. There is a tendency.

The content ratio of the polymer (P) in the liquid crystal alignment agent is preferably 10 parts by mass or more, more preferably 20 parts by mass, based on 100 parts by mass of the total of the solid components (components other than the solvent) in the liquid crystal alignment agent. The above is more preferably 30 parts by mass or more.

≪Liquid crystal alignment film and liquid crystal element≫
The liquid crystal alignment film of the present disclosure is formed by the liquid crystal alignment agent prepared as described above. In particular, the liquid crystal alignment film of the present disclosure can be produced by a method including a photoalignment step of forming a coating film using the above liquid crystal alignment agent and subjecting the coating film to a light irradiation treatment to impart liquid crystal alignment ability. preferable.
Further, the liquid crystal element of the present disclosure includes a liquid crystal alignment film formed by using the liquid crystal alignment agent described above. The operation mode of the liquid crystal in the liquid crystal element is not particularly limited, and for example, TN (Twisted Nematic) type, STN (Super Twisted Nematic) type, VA (Vertical Alignment) type (including VA-MVA type, VA-PVA type, etc.). , IPS (In-Plane Switching) type, FFS (fringe field switching) type, OCB (Optically Compensated Bend) type and the like. The liquid crystal element can be manufactured, for example, by a method including the following steps 1 to 3. In step 1, the substrate used differs depending on the desired operation mode. Steps 2 and 3 are common to each operation mode.

(Step 1: Formation of coating film)
First, a liquid crystal alignment agent is applied onto the substrate, and preferably the coated surface is heated to form a coating film on the substrate. As the substrate, for example, glass such as float glass and soda glass; a transparent substrate made of plastic such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, and poly (aliphatic olefin) can be used. As the transparent conductive film provided on one surface of the substrate, NESA film (US PPG registered trademark) made of tin oxide (SnO _2), indium oxide - ITO made of tin oxide _{(In 2} O 3 -SnO ₂₎ film Etc. can be used. When manufacturing a TN type, STN type or VA type liquid crystal element, two substrates provided with a patterned transparent conductive film are used. On the other hand, in the case of manufacturing an IPS type or FFS type liquid crystal element, a substrate provided with an electrode made of a transparent conductive film or a metal film patterned in a comb-tooth shape and a facing substrate not provided with an electrode Is used. As the metal film, a film made of a metal such as chromium can be used. The liquid crystal alignment agent is applied to the substrate on the electrode forming surface, preferably by an offset printing method, a spin coating method, a roll coater method, or an inkjet printing method.

After the liquid crystal alignment agent is applied, preheating is preferably performed for the purpose of preventing the applied liquid crystal alignment agent from dripping. The pre-baking temperature is preferably 30 to 200 ° C., and the pre-baking time is preferably 0.25 to 10 minutes. Then, a firing (post-baking) step is carried out for the purpose of completely removing the solvent and, if necessary, thermally imidizing the amic acid structure present in the polymer. The firing temperature (post-baking temperature) at this time is preferably 80 to 300 ° C., and the post-baking time is preferably 5 to 200 minutes. The film thickness of the film thus formed is preferably 0.001 to 1 μm. By applying the liquid crystal alignment agent on the substrate and then removing the organic solvent, a liquid crystal alignment film or a coating film to be a liquid crystal alignment film is formed.

(Step 2: Orientation treatment)
When manufacturing a TN type, STN type, IPS type or FFS type liquid crystal element, a treatment (alignment treatment) for imparting a liquid crystal alignment ability to the coating film formed in the above step 1 is performed. As a result, the alignment ability of the liquid crystal molecules is imparted to the coating film to form a liquid crystal alignment film. As for the orientation treatment, the polymer (P) has high light sensitivity and anisotropy can be exhibited in the coating film even with a small exposure amount. Therefore, the coating film formed on the substrate is irradiated with light to form a coating film. A photo-alignment treatment that imparts liquid crystal alignment ability to the film can be preferably used. On the other hand, in the case of producing a vertically oriented liquid crystal element, the coating film formed in the above step 1 can be used as it is as a liquid crystal alignment film, but the coating film may be subjected to an orientation treatment.

The light irradiation in the photoalignment treatment includes a method of irradiating the coating film after the post-baking step, a method of irradiating the coating film after the pre-baking step and before the post-baking step, and at least the pre-baking step and the post-baking step. In any of these methods, the coating film can be irradiated while the coating film is being heated, or the like. In the photo-alignment treatment, as the radiation to irradiate the coating film, for example, ultraviolet rays including light having a wavelength of 150 to 800 nm and visible light can be used. Preferably, it is ultraviolet light containing light having a wavelength of 200 to 400 nm. When the radiation is polarized, it may be linearly polarized or partially polarized. When the radiation to be used is linearly polarized light or partially polarized light, the irradiation may be performed from a direction perpendicular to the substrate surface, may be performed from an oblique direction, or may be performed in combination thereof. When irradiating unpolarized radiation, the direction of irradiation is diagonal.

As the light source to be used, for example, a low-pressure mercury lamp, a high-pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, an excima laser, or the like can be used. The irradiation amount of radiation is preferably 400 to 20,000 J / m ² , and more preferably 1,000 to 5,000 J / m ² . The light irradiation on the coating film may be performed while heating the coating film in order to enhance the reactivity.

In the production of the liquid crystal alignment film, the coating film subjected to the light irradiation treatment may be heated in a temperature range of 120 ° C. or higher and 280 ° C. or lower. Such heat treatment is preferable in that the liquid crystal orientation is further improved (heat reorientation) and a liquid crystal element having a further reduced AC afterimage can be obtained. This heating may be post-baking, or may be a heat treatment performed after post-baking separately from post-baking. The heating temperature is preferably 140 ° C. or higher, more preferably 150 ° C. to 250 ° C., from the viewpoint of promoting the reorientation of the molecular chains by heating. The heating time is preferably 5 minutes to 200 minutes, more preferably 10 minutes to 60 minutes.

In the production of the liquid crystal alignment film, a contact step of contacting the coating film subjected to the light irradiation treatment with water, a water-soluble organic solvent, or a mixed solvent of water and a water-soluble organic solvent may be further included. By performing such a contact step, it is possible to remove the decomposed product generated by the photoalignment treatment from the film, and it is preferable in that the generation of minute bright spots can be suppressed in the obtained liquid crystal element. Here, examples of the water-soluble organic solvent include methanol, ethanol, 1-propanol, isopropanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclopentanone. The solvent used in the contacting step is preferably water, isopropanol and a mixture thereof.

Examples of the contact method between the coating film and the solvent include, but are not limited to, spray treatment, shower treatment, immersion treatment, and liquid filling treatment. The contact time between the coating film and the solvent is not particularly limited, but is, for example, 5 seconds to 15 minutes. The coating film may be heat-treated after the contact step.

(Step 3: Construction of liquid crystal cell)
A liquid crystal cell is manufactured by preparing two substrates on which the liquid crystal alignment film is formed as described above and arranging the liquid crystal between the two substrates arranged opposite to each other. In order to manufacture a liquid crystal cell, for example, (1) two substrates are arranged facing each other through a gap (spacer) so that the liquid crystal alignment films face each other, and the peripheral portion of the two substrates is used with a sealant. A method of injecting and filling liquid crystal into the surface of the substrate and the cell gap partitioned by the sealant, and then sealing the injection holes. (2) Sealing at a predetermined place on one substrate on which the liquid crystal alignment film is formed. A method in which an agent is applied, liquid crystal is further dropped onto a predetermined number of places on the liquid crystal alignment film surface, the other substrate is bonded so that the liquid crystal alignment film faces each other, and the liquid crystal is spread over the entire surface of the substrate (ODF method). ) Etc. can be mentioned. It is desirable to remove the flow orientation at the time of filling the liquid crystal by further heating the manufactured liquid crystal cell to a temperature at which the used liquid crystal takes an isotropic phase and then slowly cooling it to room temperature.

As the sealing agent, for example, an epoxy resin containing an aluminum oxide sphere as a curing agent and a spacer can be used. As the spacer, a photo spacer, a bead spacer, or the like can be used. Examples of the liquid crystal include nematic liquid crystal and smectic liquid crystal, and among them, nematic liquid crystal is preferable. A cyclohexane-based liquid crystal, a pyrimidine-based liquid crystal, a dioxane-based liquid crystal, a bicyclooctane-based liquid crystal, a Cuban-based liquid crystal, or the like can be used. Further, for example, a cholesteric liquid crystal, a chiral agent, a ferroelectric liquid crystal or the like may be added to these liquid crystals for use.

Subsequently, if necessary, a polarizing plate is attached to the outer surface of the liquid crystal cell. Examples of the polarizing plate include a polarizing plate in which a polarizing film called an "H film" in which polyvinyl alcohol is stretch-oriented and iodine is absorbed is sandwiched between a cellulose acetate protective film, or a polarizing plate made of the H film itself. As a result, a liquid crystal element can be obtained.

According to the liquid crystal alignment agent containing the polymer (P), the liquid crystal having good photoreactivity or rubbing resistance of the coating film and having the liquid crystal orientation, AC afterimage characteristics and voltage holding characteristics improved in a well-balanced manner. Although the reason why the element can be obtained is not clear, the nitrogen-containing heterocycle contained in the structural unit derived from diamine of the polymer (P) photoinduces the coating film from the diamine skeleton to the acid anhydride skeleton when the coating film is irradiated with light. It is presumed that the photoreactivity was enhanced by electron transfer (electron transfer sensitization reaction). As a result, it is presumed that the degree of orientation order of the liquid crystal of the obtained liquid crystal element could be improved and the AC afterimage could be reduced. In addition, the hydrogen-bonding functional groups (Z ¹ , Z ² ) of the polymer (P) act on intermolecular interactions, which results in a coating film with high rubbing resistance and a liquid crystal element with a high voltage retention. Is presumed to have been obtained.

The liquid crystal elements of the present disclosure can be effectively applied to various applications, for example, clocks, portable games, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors. , LCD TVs, information displays and other display devices, dimming films and the like. Further, the liquid crystal element formed by using the liquid crystal alignment agent of the present disclosure can also be applied to a retardation film.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

The structures and abbreviations of the main compounds used in the examples below are as follows.
(Tetracarboxylic dianhydride)
TA-1; (1R, 2R, 3S, 4S) -1,3-dimethylcyclobutane-1,2,3,4-tetracarboxylic dianhydride TA-2; 1,2,3,4-cyclobutanetetracarboxylic Acid dianhydride TA-3; 2,3,5-tricarboxycyclopentyl acetate dianhydride TA-4; Bicyclo [3,3,0] octane-2,4,6,8-tetracarboxylic dianhydride TA -5; pyromellitic dianhydride TA-6; 4,4'-biphthalic dianhydride

(Specific diamine)
DA-1; N, N'-bis (2-((5-amino-2-pyridyl) (methyl) amino) ethyl) urea DA-2; N, N'-bis (2-((5-amino-) 2-Pyridyl) oxy) ethyl) urea DA-3; N, N'-bis (2-((5-amino-2-pyridyl) (methyl) amino) ethyl) oxamide DA-4; N, N'-bis (2-((5-Amino-2-pyridyl) oxy) ethyl) oxamide DA-5; 5-amino-2-pyridyl-6- (3- (6-((5-amino-2-pyridyl) amino)) -6-oxohexyl) ureido) hexaneamide DA-6; 1,1'-(hexane-1,6-diyl) bis (3- (2-((5-amino-2-pyridyl) (methyl) amino ) Ethyl) Urea)
(Other diamines)
DB-1; para-phenylenediamine DB-2; N, N'-(4-aminophenityl) urea DA-3; N, N'-di (5-amino-2-pyridyl) -N, N'-dimethyl Ethylenediamine DB-4; Bis adipate (4-aminophenyl)
DB-5; N, N'-bis (2-((4-aminophenyl) (methyl) amino) ethyl) urea

(solvent)
NMP; N-methyl-2-pyrrolidone BC; butyl cellosolve DMAc; N, N-dimethylacetamide

<Compound synthesis>
[Synthesis Example 1]
2-Chloroethylamine hydrochloride (11.60 g, 0.10 mol), 2-chloroethyl isocyanate (10.55 g, 0.10 mol), and 100 mL of methylene chloride were placed in a three-necked flask equipped with a nitrogen introduction tube. .. Triethylamine (11.13 g, 0.11 mol) was added dropwise under ice-cooling, and the mixture was stirred at room temperature for 24 hours. After completion of the reaction, 100 mL of water was poured into the reaction solution, the mixture was stirred, and the suspended solution was filtered. The obtained precipitate was washed with stirring in 100 mL of water and then vacuum dried to obtain N, N'-bis (2-chloroethyl) urea (16) represented by the following formula (DA-1-a). .7 g, yield 90%) was obtained.
Subsequently, N, N'-bis (2-chloroethyl) urea (14.80 g, 0.08 mol), ethanol (100 mL), and 40% methylamine were placed in a three-necked flask equipped with a reflux tube and a nitrogen introduction tube. An aqueous solution (124 g, 1.6 mol) was added, and the mixture was stirred at 40 ° C. for 48 hours. The raw material was dissolved with the reaction, and a colorless and transparent reaction solution was obtained. After completion of the reaction, potassium hydroxide (8.98 g, 0.16 mol) was added to the reaction solution under ice-cooling to neutralize and concentrate under reduced pressure. Ethanol is added to the obtained concentrate for extraction, filtration is performed to remove insoluble salts, and then concentration is performed under reduced pressure to obtain N, N'-bis (N, N'-bis) represented by the following formula (DA-1-b). A crude product of 2- (methylamino) ethyl) urea (15.0 g) was obtained.

[Synthesis Example 2]
N, N'-bis (2- (methylamino) ethyl) urea (6.97 g, 40 mmol), triethylamine (16.7 mL, 120 mmol), and DMAc in a three-necked flask equipped with a reflux tube and a nitrogen introduction tube. (80 mL) was added. 2-Fluoro-5-nitropyridine (11.37 g, 80 mmol) was added dropwise under nitrogen, and the mixture was stirred at 60 ° C. for 12 hours. After completion of the reaction, the reaction solution was filtered and concentrated under reduced pressure. The obtained precipitate was recrystallized from ethyl acetate and vacuum dried to obtain a nitro compound intermediate product (12.24 g, yield 78%) represented by the following formula (DA-1-c). ..
Subsequently, a nitro compound intermediate product (2.09 g, 5.0 mmol), 5% palladium carbon (0.21 g), and ethanol (30 mL) were added to a 100 mL autoclave, and hydrogen gas was blown to 0.4 MPa. The mixture was stirred at 50 ° C. for 12 hours. After completion of the reaction, the reaction solution was filtered through Celite and concentrated under reduced pressure. The obtained precipitate was washed with ethanol and vacuum dried to obtain a diamine (1.60 g, yield 65%) represented by the following formula (DA-1).

[Synthesis Example 3]
O- (5-nitro-2-pyridyl) ethanolamine represented by the following formula (DA-2-b) was synthesized according to the following synthesis scheme.

[Synthesis Example 4]
O- (5-nitro-2-pyridyl) ethanolamine (1.10 g, 6.0 mmol), carbonyldiimidazole (0.58 g, 3) in a three-necked flask equipped with a reflux tube, thermometer and nitrogen introduction tube. .6 mmol) and DMAc (30 mL) were added and stirred at room temperature for 24 hours. After completion of the reaction, the mixture was concentrated under reduced pressure, and the obtained precipitate was recrystallized from ethyl acetate and vacuum dried to obtain a nitro compound intermediate product (0.91 g, represented by the following formula (DA-2-c)). Yield 77%) was obtained.
Subsequently, a nitro compound intermediate product (1.57 g, 4.0 mmol), 5% palladium carbon (0.16 g), and ethanol (30 mL) were added to a 100 mL autoclave, and hydrogen gas was blown up to 0.4 MPa. The mixture was stirred at 50 ° C. for 12 hours. After completion of the reaction, the reaction solution was filtered through Celite and concentrated under reduced pressure. The obtained precipitate was washed with ethanol and vacuum dried to obtain a diamine (1.00 g, yield 63%) represented by the following formula (DA-2).

[Synthesis Example 5]
N-Methyl-N- (5-nitro-2-pyridyl) ethylenediamine represented by the following formula (DA-3-b) was synthesized according to the following synthesis scheme.

[Synthesis Example 6]
N-Methyl-N- (5-nitro-2-pyridyl) ethylenediamine (1.18 g, 6.0 mmol), triethylamine (0.91 g, 0.91 g,) in a three-necked flask equipped with a reflux tube, a thermometer and a nitrogen introduction tube. 9.0 mmol) and DMAc (30 mL) were added, and the mixture was stirred under ice-cooling. Oxalyl chloride (0.38 g, 3.0 mmol) was added dropwise, and the mixture was stirred at room temperature for 8 hours. After completion of the reaction, the mixture was concentrated under reduced pressure, and the obtained precipitate was recrystallized from ethyl acetate and vacuum dried to obtain a nitro compound intermediate product (1.11 g, represented by the following formula (DA-3-c)). The yield was 83%).
Subsequently, a nitro compound intermediate product (1.79 g, 4.0 mmol), 5% palladium carbon (0.18 g), and ethanol (30 mL) were added to a 100 mL autoclave, and hydrogen gas was blown up to 0.4 MPa. The mixture was stirred at 50 ° C. for 12 hours. After completion of the reaction, the reaction solution was filtered through Celite and concentrated under reduced pressure. The obtained precipitate was washed with ethanol and vacuum dried to obtain a diamine (0.74 g, yield 48%) represented by the following formula (DA-3).

[Synthesis Example 7]
The diamine represented by the above formula (DA-4) was synthesized according to the following synthesis scheme.

[Synthesis Example 8]
The diamine represented by the above formula (DA-5) was synthesized according to the following synthesis scheme.

[Synthesis Example 9]
The diamine represented by the above formula (DA-6) was synthesized according to the following synthesis scheme.

[Synthesis Example 10]
The diamine represented by the above formula (DB-5) was synthesized according to the following synthesis scheme.

<Synthesis of polymer>
[Synthesis Example 11]
60 mol parts of diamine (DA-1) and 40 mol parts of diamine (DB-1) were dissolved in NMP, 0.95 equivalent of tetracarboxylic dianhydride (TA-1) was added, and the reaction was carried out at room temperature for 6 hours. Was carried out to obtain a solution of polyamic acid. To the obtained solution, 0.8 equivalents of 1-methylpiperidine and acetic anhydride were added to the carboxyl group of the polyamic acid, and the mixture was heated and stirred at 60 ° C. for 3 hours. The obtained solution was repeatedly concentrated under reduced pressure and diluted with NMP to obtain a 15% by mass solution of polyimide (PI-1) having a partial structure represented by the following formula (PI-1). Polyimide (PI-1) of ¹ H-NMR spectrum ^(DMSO-d 6, 400MHz) was measured, aromatic protons (δ6.4~9.0ppm) and main chain amide protons (δ9.8~10.3ppm) When the imidization rate was calculated from the integral ratio of the acetyl terminal amide proton (δ9.6 to 9.8 ppm), the imidization rate was 70%.

[Synthesis Examples 12 to 17]
Polyimides (PI-2 to PI-7) were obtained in the same manner as in Synthesis Example 11 except that the types and molar ratios of the tetracarboxylic dianhydride and the diamine compound were changed as shown in Table 1 below. The numerical values in Table 1 represent the usage ratio (molar part) of each compound to 100 mol parts of the total amount of the tetracarboxylic dianhydride used for the synthesis for the tetracarboxylic dianhydride, and for the diamine compound. Indicates the usage ratio (molar part) of each compound with respect to 100 mol parts of the total amount of the diamine compounds used in the synthesis.

[Synthesis Example 18]
Diamine (DA-1) is dissolved in NMP, 0.95 equivalent of tetracarboxylic dianhydride (TA-5) is added, and the reaction is carried out at room temperature for 6 hours, which is represented by the following formula (PA-1). A 15% by mass solution of polyamic acid (PA-1) having a partial structure was obtained.

[Synthesis Examples 19 to 27]
Polyamic acids (PA-2 to PA-10) were obtained in the same manner as in Synthesis Example 18, except that the types and molar ratios of the tetracarboxylic dianhydride and the diamine compound were changed as shown in Table 1 below. ..

[Example 1: Photo-alignment FFS type liquid crystal display element]
(1) Preparation of liquid crystal alignment agent Using the solution of polyimide (PI-1) obtained in Synthesis Example 11, it was diluted with NMP and BC to have a solid content concentration of 4.0% by mass and a solvent composition ratio of NMP: A solution having BC = 80: 20 (mass ratio) was obtained. A liquid crystal alignment agent (R-1) was prepared by filtering this solution through a filter having a pore size of 0.2 μm.

(2) Formation of liquid crystal alignment film by photoalignment method On each surface of a glass substrate in which a flat plate electrode, an insulating layer and a comb-shaped electrode are laminated on one side in this order, and a facing glass substrate on which no electrode is provided. The liquid crystal aligning agent (R-1) prepared in (1) above is applied using a spinner so that the film thickness is 0.1 μm, dried (prebaked) for 1 minute on a hot plate at 80 ° C., and then applied. A film was formed. The surface of the coating film was subjected to photoalignment treatment by irradiating the surface of the coating film with ultraviolet rays of 2,000 J / m ² including a linearly polarized 254 nm emission line from the normal direction of the substrate using an Hg-Xe lamp. The coating film subjected to the photo-alignment treatment was heated in an oven at 230 ° C. in which the inside of the chamber was replaced with nitrogen for 30 minutes and heat-treated (post-baked) to form a liquid crystal alignment film.

(3) Manufacture of liquid crystal display element With respect to the pair of substrates having the liquid crystal alignment film produced in (2) above, an aluminum oxide ball having a diameter of 5.5 μm is contained, leaving a liquid crystal injection port on the edge of the surface on which the liquid crystal alignment film is formed. After applying the epoxy resin adhesive by screen printing, the substrates are overlapped and crimped so that the projection direction of the polarization axis on the substrate surface at the time of light irradiation is antiparallel, and the adhesive is heated at 150 ° C. for 1 hour. It was cured. Next, a nematic liquid crystal (MLC-7028 manufactured by Merck & Co., Inc.) was filled between the pair of substrates from the liquid crystal injection port, and then the liquid crystal injection port was sealed with an epoxy adhesive. Further, in order to eliminate the flow orientation at the time of liquid crystal injection, this was heated at 120 ° C. and then slowly cooled to room temperature. Next, a polarizing plate was attached to both outer surfaces of the substrate to manufacture an FFS type liquid crystal display element.

(4) Evaluation of photoreactivity The liquid crystal alignment agent (R-1) prepared in (1) above was applied onto a quartz substrate using a spinner, dried on a hot plate at 80 ° C. for 1 minute, and then inside the oven. Was dried in a nitrogen-substituted oven at 230 ° C. for 30 minutes to form a coating film having an average film thickness of 0.1 μm. The surface of the coating film was irradiated with an ultraviolet ray of 1,000 J / m2 including a linearly polarized 254 nm emission line from the substrate normal direction using an Hg-Xe lamp. The photoreactivity was evaluated from the absorption derived from the substituted maleimide compound generated by photolysis. Specifically, the absorbance of the coating film after light irradiation at the maximum absorption wavelength in the region of 220 to 250 nm was measured, and the rate of increase with respect to the absorbance of the coating film before light irradiation at that wavelength was calculated. When the rate of increase in absorbance was 20% or more, it was "excellent", when the rate of increase in absorbance was 10% or more and less than 20%, it was "good", and when the rate of increase in absorbance was less than 10%. It was considered "bad". As a result, it was evaluated as "excellent" in this example.

(5) Evaluation of liquid crystal orientation With respect to the liquid crystal display element manufactured in (3) above, the presence or absence of anomalous domains in the change in brightness when a voltage of 5 V is turned ON / OFF (applied / released) is determined by a microscope at a magnification of 50 times. Observed. In the evaluation, the orientation order was "good" when no abnormal domain was observed, and "poor" when an abnormal domain was observed. As a result, it was evaluated as "good" in this example.

(6) Evaluation of AC Afterimage Characteristics The FFS type liquid crystal cell was produced by performing the same operation as in (3) above except that the polarizing plates were not attached to both outer surfaces of the substrate. This FFS type liquid crystal cell is driven at an AC voltage of 10 V for 30 hours, and then using a device in which a polarizer and an analyzer are arranged between a light source and a light amount detector, the minimum relative represented by the following mathematical formula (2) is used. The transmittance (%) was measured.
Minimum relative transmittance (%) = (β-B ₀ ) / (B _100- B ₀ ) x 100 ... (2)
(In formula (2), B ₀ is the amount of light transmitted under the cross Nicol _{in the blank. B 100} is the amount of light transmitted under the paranicol in the blank. β is the amount of light transmitted under the cross Nicol. This is the minimum amount of light transmitted by sandwiching a liquid crystal cell between detectors.)
The black level in the dark state is represented by the minimum relative transmittance of the liquid crystal cell, and in the FFS type liquid crystal cell, the smaller the black level in the dark state, the better the contrast. Those with a minimum relative transmittance of less than 0.2% are "excellent", those with a minimum relative transmittance of 0.2% or more and less than 0.5% are "good", and those with a minimum relative transmittance of 0.5% or more and less than 1.0% are "acceptable". , 1.0% or more was regarded as "defective". As a result, it was evaluated as "excellent" in this example.

(7) Evaluation of voltage retention rate After applying a voltage of 5 V to the liquid crystal cell manufactured above in a span of 60 microseconds and 167 milliseconds, the voltage retention rate was measured 167 ms after the application was released. .. A voltage holding rate of 99.5% or more is "excellent", 99.0% or more and less than 99.5% is "good", 98.0% or more and less than 99.0% is "acceptable", and less than 98.0%. It was considered "bad". As a result, it was evaluated as "excellent" in this example. As the voltage holding ratio measuring device, the model name "VHR-1" manufactured by Toyo Corporation was used.

[Examples 2 to 4, Comparative Examples 1 to 2, Reference Example 1]
In Example 1 above, a liquid crystal alignment agent was prepared and a liquid crystal alignment film was formed by a photoalignment method in the same manner as in Example 1 except that the polymer contained in the liquid crystal alignment agent was changed as shown in Table 2 below. At the same time, FFS type liquid crystal display elements and liquid crystal cells were manufactured and various evaluations were performed. The evaluation results are shown in Table 2 below.

[Example 5: Rubbing orientation FFS type liquid crystal display element]
(1) Preparation of liquid crystal alignment agent Using the solution of polyamic acid (PA-1) obtained in Synthesis Example 18, diluted with NMP and BC, the solid content concentration was 4.0% by mass and the solvent composition ratio was NMP. A solution having a ratio of BC = 80: 20 (mass ratio) was obtained. A liquid crystal alignment agent (R-5) was prepared by filtering this solution through a filter having a pore size of 0.2 μm.

(2) Formation of liquid crystal alignment film by rubbing method On each surface of a glass substrate in which a flat plate electrode, an insulating layer and a comb-shaped electrode are laminated on one side in this order, and a facing glass substrate on which no electrode is provided. The liquid crystal aligning agent (R-5) prepared in (1) above was applied using a spinner, dried on a hot plate at 80 ° C. for 1 minute, and then the inside of the refrigerator was replaced with nitrogen in an oven at 230 ° C. for 30 minutes. Drying was performed to form a coating film having an average thickness of 0.1 μm. A rubbing treatment was performed on the surface of the coating film using a rubbing machine having a roll wrapped with a nylon cloth at a roll rotation speed of 1000 rpm, a stage moving speed of 25 mm / sec, and a hair-foot pushing length of 0.4 mm. The coating film subjected to the rubbing alignment treatment was ultrasonically washed in ultrapure water for 1 minute and then dried in an oven at 100 ° C. for 10 minutes to form a liquid crystal alignment film.

(3) Manufacture of liquid crystal display element With respect to the pair of substrates having the liquid crystal alignment film produced in (2) above, an aluminum oxide ball having a diameter of 5.5 μm is contained, leaving a liquid crystal injection port on the edge of the surface on which the liquid crystal alignment film is formed. After applying the epoxy resin adhesive by screen printing, the substrates are overlapped and crimped so that the projection direction of the polarization axis on the substrate surface at the time of light irradiation is antiparallel, and the adhesive is heated at 150 ° C. for 1 hour. It was cured. Next, a nematic liquid crystal (MLC-7028 manufactured by Merck & Co., Inc.) was filled between the pair of substrates from the liquid crystal injection port, and then the liquid crystal injection port was sealed with an epoxy adhesive. Further, in order to eliminate the flow orientation at the time of liquid crystal injection, this was heated at 120 ° C. and then slowly cooled to room temperature. Next, a polarizing plate was attached to both outer surfaces of the substrate to manufacture an FFS type liquid crystal display element.

(4) Evaluation of rubbing resistance (evaluation of the amount of foreign matter generated by the rubbing process)
The liquid crystal alignment agent (R-5) prepared in (1) above was applied to the transparent electrode surface of a glass substrate with a transparent electrode made of an ITO film using a spinner, and dried on a hot plate at 80 ° C. for 1 minute. After that, the inside of the refrigerator was dried in a nitrogen-substituted oven at 230 ° C. for 30 minutes to form a coating film having an average film thickness of 0.1 μm. Using a rubbing machine having a roll wrapped with a cotton cloth on the surface of this coating film, the rubbing treatment was performed 5 times at a roll rotation speed of 1000 rpm, a stage moving speed of 25 mm / sec, and a fluff pushing length of 0.4 mm. , A substrate for evaluating the amount of foreign matter was obtained. The foreign matter on the obtained foreign matter amount evaluation substrate was observed with an optical microscope, and the number of foreign matter in the region of 500 μm × 500 μm was counted. Those having less than 5 foreign substances in the region of 500 μm × 500 μm were regarded as “excellent”, those having 5 or more and less than 10 were regarded as “acceptable”, and those having 10 or more were regarded as “poor”. As a result, no foreign matter was confirmed in this example, and the evaluation was "excellent".

(5) Evaluation of liquid crystal orientation The liquid crystal orientation was evaluated in the same manner as in (5) of Example 1. As a result, it was evaluated as "good" in this example.
(6) Evaluation of AC Afterimage Characteristics The AC afterimage characteristics were evaluated in the same manner as in (6) of Example 1. As a result, it was evaluated as "excellent" in this example.
(7) Evaluation of voltage retention rate The voltage retention rate was evaluated in the same manner as in (7) of Example 1. As a result, it was evaluated as "excellent" in this example.

[Examples 6 to 8, Comparative Example 3]
In Example 5, the liquid crystal alignment agent was prepared in the same manner as in Example 5 except that the polymer contained in the liquid crystal alignment agent was changed as shown in Table 2 below, and a liquid crystal alignment film was formed by a rubbing method. , FFS type liquid crystal display element and liquid crystal cell were manufactured and various evaluations were performed. The evaluation results are shown in Table 2 below.

[Examples 9 to 12, Comparative Example 4]
In Example 1 above, a liquid crystal alignment agent was prepared and a liquid crystal alignment film was formed by a photoalignment method in the same manner as in Example 1 except that the polymer contained in the liquid crystal alignment agent was changed as shown in Table 2 below. At the same time, FFS type liquid crystal display elements and liquid crystal cells were manufactured and various evaluations were performed. The evaluation results are shown in Table 2 below. In Examples 9 to 12 and Comparative Example 4, two types of polymers (polymer 1 and polymer 2) were mixed at a compounding ratio of polymer 1: polymer 2 = 40:60 (solid content equivalent mass ratio). It was contained in the liquid crystal aligning agent. In Examples 9 to 12 and Comparative Example 4, the polymer 1 is a photosensitive polymer, and the polymer 2 is a non-photosensitive polymer.

As shown in Table 2, the liquid crystal alignment agents of Examples 1 to 12 containing the polymer (P) were evaluated as "excellent" in photoreactivity or rubbing resistance, and were evaluated in terms of AC afterimage characteristics and voltage retention. Was "excellent" or "good", and various characteristics were well-balanced. On the other hand, the liquid crystal alignment agents of Comparative Examples 1 to 4 containing no polymer (P) were inferior to those of Examples in at least one of rubbing resistance, AC afterimage characteristics and voltage retention. Further, in Reference Example 1, although no defect was evaluated, the photoreactivity and AC afterimage characteristics were inferior to those of Examples.

Here, considering the results of Examples, all of Examples 1 to 4 and 9 to 12 were "good" or "excellent" in terms of photoreactivity. Since the polymer (P) has a pyridine ring and an electron donating group as a diamine-derived partial structure, photoinduced electron transfer (electron transfer sensitization reaction) from the diamine-derived partial structure to the substituted cyclobutane ring ), It is presumed that the photolysis by the retro [2 + 2] reaction of the substituted cyclobutane ring was promoted.

The rubbing resistance was "excellent" in all of Examples 5 to 8. Since these have hydrogen-bonding functional groups (urea bonds, oxamide bonds) in the polymer (P), the toughness of the liquid crystal alignment film is improved by the intermolecular interaction, and as a result, the film is scraped by the rubbing treatment. Is suppressed, and it is presumed that the number of foreign substances has decreased. Further, regarding the voltage holding ratio, all of Examples 1 to 12 were "good" or "excellent". Since these have a hydrogen-bonding functional group (urea bond or oxamide bond) in the polymer (P), the molecular motility is suppressed by the intermolecular interaction, and as a result, the dielectric polarization is suppressed and the voltage is maintained. It is estimated that the rate has improved.

In Examples 9 to 12 containing the photosensitive polymer 1 and the non-photosensitive polymer 2, as is clear from the comparison with Comparative Example 2, the decrease in the voltage retention rate derived from the polymer 1 was suppressed. Was there. Further, in Examples 9 to 12, the evaluation of the liquid crystal orientation and the AC afterimage characteristics was "excellent" as in Comparative Example 2 containing only the photosensitive polymer 1. These are highly polar because the non-photosensitive polymer (P) contained in Examples 9 to 12 has a hydrogen-bonding functional group (urea bond, oxamide bond) and a basic group (pyridine ring). Therefore, it is presumed that the layer separability with the relatively low-polarity polymer 1 was improved, and that the photosensitive polymer 1 was localized at the interface of the liquid crystal alignment film, so that good liquid crystal orientation could be exhibited. To. On the other hand, since the non-photosensitive polymer 2 contained in Comparative Example 4 does not have a pyridine ring, the carboxylic acid contained in the polymer 2 is different from the basic pyridine ring contained in the photosensitive polymer 1. It is presumed that the acid-base interaction between the polymers is easy, the compatibility between the polymer 1 and the polymer 2 is improved, the non-photosensitive polymer 2 is likely to be present at the interface of the liquid crystal alignment film, and the liquid crystal orientation is lowered. To. It should be noted that the above consideration is merely speculation and does not limit the content of the present disclosure.

As described above, according to the liquid crystal alignment agent of the present disclosure containing the polymer (P), a liquid crystal element having good photoreactivity or rubbing resistance of the liquid crystal alignment film and good AC afterimage characteristics and voltage retention is obtained. It turns out that it can be done.

Claims (8)

A liquid crystal alignment agent containing a polymer (P) having at least one selected from the group consisting of a partial structure represented by the following formula (1) and a partial structure represented by the following formula (2).

(In the formulas (1) and (2), X ¹ is a tetravalent organic group, X ² is a divalent organic group represented by the following formula (3), and R ^{1 and R 2} are divalent organic groups. , Each independently is a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms.)

(In the formula (3), A ¹ and A ² are independently divalent aromatic ring groups, respectively. However, ^{at least one of A 1} and A ² is a divalent nitrogen-containing heterocyclic group R. ³ and R ⁵ are independently divalent aliphatic hydrocarbon groups ^{having 1 to 10 carbon atoms, and R 4} is a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms or the aliphatic hydrocarbon group. between carbon bond, an oxygen atom, a sulfur atom, - carbon hydrogen group "- COO -", "- OCO -", ^{"- Si (R 21 R 22)} - " or "-Si ^(R 21 ^{R 22)} - O-Si (R ²³ R ²⁴ )-"(R ^{21 to} R ²⁴ are each independently a hydrogen atom or an aliphatic hydrocarbon group having 1 to 6 carbon atoms) is a divalent group having Y. ¹ and Y ² are independently single-bonded, oxygen atom, sulfur atom, "-COO-", "-OCO-", "-NR ^6- ", "-NR ^6- CO-" or "-". CO-NR ^6- "(R ⁶ is a hydrogen atom or a monovalent organic group, which ^{may be bonded to an adjacent R 3} or R ⁵ to form a ring structure). Z ¹ and Z ² is any of the groups independently represented by the following formulas (4) to (6). N is 0 or 1. “*” Indicates a bond.)

(In formula (4), ^{R 7} is a hydrogen atom or a monovalent organic group, ^{B 1} is "- ^{NR 14} -", ^"* 1 ^{-CO-NR 14} -", an oxygen atom, ^{"* 1} - CO-O -, "" ^{- NR 14} -CO-NR 14 ^- "or" ^* 1 ^-NR 14 -CO-O - ^{"(R 14} is a hydrogen atom or a monovalent organic group," ^{* 1} " Represents a bond with a carbonyl group.) In formula (5), R ⁸ and R ⁹ are independently hydrogen atoms or monovalent organic groups. In formula (6), R ^{10 to} R ¹³ are independently hydrogen atoms or monovalent organic groups. “*” Indicates a bond.) The liquid crystal alignment agent according to claim 1, wherein A ¹ and A ^{2 are independently divalent nitrogen-containing heterocyclic groups.} Y ¹ and Y ² are independently oxygen atom, sulfur atom or "-NR ^6- ", respectively.
According to claim ^{2, the Y 1} and Y 2 are bonded to a carbon atom adjacent to a nitrogen atom in the ring of the nitrogen-containing heterocycle with respect to the nitrogen-containing heterocycle of the ^{A 1} and A ^2. The liquid crystal alignment agent described. The liquid crystal alignment agent according to any one of claims 1 to 3, wherein X ^{1 is a tetravalent organic group represented by the following formula (11).}

(In the formula (11), R ^{31 to} R ³³ are independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkyl halide group having 1 to 6 carbon atoms, and 1 to 6 carbon atoms, respectively. Alkoxy group, thioalkyl group having 1 to 6 carbon atoms, alkenyl group having 2 to 6 carbon atoms, alkynyl group having 2 to 6 carbon atoms, or "-COR ³⁰ " (R ³⁰ is an alkyl group having 1 to 6 carbon atoms). , Fluorine-containing alkyl group, alkoxy group or fluorine-containing alkoxy group.) R ³⁴ is a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkyl halide group having 1 to 6 carbon atoms, and 1 carbon atom. Alkoxy groups of ~ 6; thioalkyl groups of 1-6 carbon atoms, alkenyl groups of 2-6 carbon atoms, alkynyl groups of 2-6 carbon atoms, or "-COR ³⁰ ", but of R ^31- R ³⁴ . Adjacent groups may be bonded to each other to form a ring structure. “*” Indicates a bond.) A liquid crystal alignment film formed by using the liquid crystal alignment agent according to any one of claims 1 to 4. A liquid crystal alignment film comprising a photoalignment step of forming a coating film using the liquid crystal alignment agent according to any one of claims 1 to 4 and subjecting the coating film to a light irradiation treatment to impart liquid crystal alignment ability. Manufacturing method. The method for producing a liquid crystal alignment film according to claim 6, further comprising a heating step of heating the coating film subjected to the light irradiation treatment in a temperature range of 120 ° C. or higher and 280 ° C. or lower. A liquid crystal element including the liquid crystal alignment film according to claim 5.