JP2024061619A - Liquid crystal alignment agent, liquid crystal alignment film, liquid crystal element, polymer and diamine - Google Patents

Abstract

To provide a liquid crystal alignment agent that has a high voltage holding rate, is excellent in a pretilt angle provision characteristic, and can obtain a liquid crystal element, which has a small change of pretilt angle even when driven for a long period and is excellent in reliability.SOLUTION: A compound [A] having a heterocyclic structure (a) represented by a formula (1-1), a formula (1-2) or a formula (1-3) is contained in a liquid crystal alignment agent. In the formulas (1-1) to (1-3), m1 and m2 each independently represent an integer from 1 to 3. Z1 represents a single bond or a carbonyl group. "*" represents a bond.SELECTED DRAWING: None

Description

The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, a liquid crystal element, a polymer, and a diamine.

Various driving methods have been developed for liquid crystal elements, with different electrode structures and physical properties of liquid crystal molecules. For example, various types of liquid crystal elements are known, such as TN type, STN type, VA type, MVA type, in-plane switching type (IPS type), FFS type, and optically compensated bend type (OCB type). These liquid crystal elements have a liquid crystal alignment film for orienting the liquid crystal molecules. A liquid crystal alignment film is generally formed on a substrate by applying a liquid crystal alignment agent, which is a polymer component dissolved or dispersed in an organic solvent, to the substrate surface, and preferably by heating.

Conventional techniques for imparting a pretilt angle to liquid crystal molecules include the rubbing method, in which the surface of a coating film formed from a liquid crystal alignment agent is rubbed in a certain direction with a cloth or the like, and the photoalignment method, in which a photosensitive coating film is irradiated with radiation. A method (PSA (Polymer Sustained Alignment)) has also been proposed in the past, in which a photopolymerizable compound is added in advance to a liquid crystal composition, and radiation is irradiated while a voltage is applied to the liquid crystal cell to impart a pretilt angle. It is said that the PSA technique can improve the response speed of liquid crystal molecules and also improve the transmittance.

In recent years, with the demand for higher definition and versatility of liquid crystal elements, further improvements in the voltage retention characteristics and display quality of liquid crystal elements are required, and various liquid crystal alignment agents have been proposed to achieve this (see, for example, Patent Document 1). Patent Document 1 discloses the formation of a liquid crystal alignment film using a photoalignment composition containing a polyimide or polyamic acid obtained using a diamine having a specific nitrogen-containing heterocyclic group.

Conventionally, a radical generating structure that generates radicals by absorbing light has been introduced into the polymer components that make up the liquid crystal alignment film, thereby improving the response speed of the liquid crystal in PSA type liquid crystal display elements and increasing the reliability of the liquid crystal display elements (see, for example, Patent Documents 2 and 3).

JP 2020-509426 A International Publication No. 2017/030170 JP 2020-073680 A

When improving the response speed and reliability of liquid crystal in liquid crystal elements by blending a component having a radical generating structure into a liquid crystal alignment agent, it is desirable to introduce a sufficient amount of the radical generating structure into the liquid crystal alignment agent in order to fully obtain the effect of introducing the radical generating structure. On the other hand, the inventors have found that when a large amount of the radical generating structure is introduced, the voltage retention rate of the liquid crystal element is likely to decrease due to the generated decomposition products. Furthermore, it is desirable for the liquid crystal element to have high reliability and little change in display characteristics and display quality due to irradiation with light such as a backlight, even when a radical generating structure is introduced.

The present invention has been made in consideration of the above problems, and its main objective is to provide a liquid crystal alignment agent that can provide a liquid crystal element with a high voltage retention rate and excellent reliability.

The inventors have conducted extensive research and have come to a solution to the above problem by using a compound having a specific heterocyclic structure as a component of a liquid crystal alignment agent. The present invention provides the following means.

（式（１－１）～式（１－３）中、ｍ１及びｍ２は、それぞれ独立して１～３の整数である。Ｚ^１は単結合又はカルボニル基である。「＊」は結合手を表す。） [1] A liquid crystal aligning agent comprising a compound [A] having a heterocyclic structure (a) represented by the following formula (1-1), (1-2) or (1-3):

(In formulas (1-1) to (1-3), m1 and m2 each independently represent an integer from 1 to 3. ^Z1 represents a single bond or a carbonyl group. "*" represents a bond.)

（式（２－１）中、Ａｒ^１は（ｐ＋２）価の芳香環基である。ｐは１～４の整数である。ｒは１又は２である。Ｘ^１１は、ｒが１の場合に、単結合、－Ｏ－、－Ｓ－、－ＣＯ－、－ＣＯＯ－、－ＮＲ^３－、－ＣＯ－ＮＲ^３－、－ＣＨ_２－Ｏ－、－ＣＨ_２－ＣＯ－又は－ＣＨ_２－ＯＣＯ－であり、ｒが２の場合に、窒素原子又は＊－ＣＯ－Ｎ（－＊）_２である。「＊」は結合手を表す。Ｒ^１は、単結合、炭素数１～２０の２価の炭化水素基、当該炭化水素基の炭素－炭素結合間に－Ｏ－、－Ｓ－、－ＣＯ－、－ＣＯＯ－、－ＮＲ^３－若しくは－ＣＯＮＲ^３－を含む炭素数２～２０の２価の基Ｒ^ｋ１、又は、２価の炭化水素基若しくは２価の基Ｒ^ｋ１における少なくとも一部の水素原子が置換基で置き換えられてなる基である。Ｒ^３は、水素原子又は１価の有機基である。Ｙ^１１は、下記式（１－１）、式（１－２）又は式（１－３）で表される複素環構造（ａ）を有する２価の基である。Ｒ^２は、水素原子又は１価の有機基である。式中にＸ^１１、Ｒ^１、Ｙ^１１、Ｒ^２、ｒが複数存在する場合、複数のＸ^１１、Ｒ^１、Ｙ^１１、Ｒ^２、ｒは互いに同一又は異なる。）

（式（２－２）中、Ａｒ^２及びＡｒ^３は、それぞれ独立して２価の芳香環基である。Ｒ^４及びＲ^５は、それぞれ独立して単結合又は２価の有機基である。Ｙ^１２は、上記式（１－１）、式（１－２）又は式（１－３）で表される複素環構造（ａ）を有する２価の基である。ｋは０～３の整数である。式中にＹ^１２、Ｒ^５が複数存在する場合、複数のＹ^１２、Ｒ^５は互いに同一又は異なる。）

（式（２－３）中、Ａｒ^４及びＡｒ^５は、それぞれ独立して２価の芳香環基である。Ｒ^６は３価の有機基である。Ｘ^１２は、単結合、－Ｏ－、－Ｓ－、－ＣＯ－、－ＣＯＯ－、－ＮＲ^９－、－ＣＯ－ＮＲ^９－、－ＣＨ_２－Ｏ－、－ＣＨ_２－ＣＯ－又は－ＣＨ_２－ＯＣＯ－である。Ｒ^７は、単結合、炭素数１～２０の２価の炭化水素基、当該炭化水素基の炭素－炭素結合間に－Ｏ－、－Ｓ－、－ＣＯ－、－ＣＯＯ－、－ＮＲ^９－若しくは－ＣＯ－ＮＲ^９－を含む炭素数２～２０の２価の基Ｒ^ｋ２、又は、２価の炭化水素基若しくは２価の基Ｒ^ｋ２における少なくとも一部の水素原子が置換基で置き換えられてなる基である。Ｒ^９は、水素原子又は１価の有機基である。Ｙ^１３は、下記式（１－１）、式（１－２）又は式（１－３）で表される複素環構造（ａ）を有する２価の基である。Ｒ^８は、水素原子又は１価の有機基である。） [2] A liquid crystal alignment film formed by using the liquid crystal aligning agent according to [1] above.
[3] A liquid crystal element comprising the liquid crystal alignment film according to [2] above.
[4] A method for producing a liquid crystal alignment film, comprising: forming a coating film using the liquid crystal aligning agent according to [1] above; and irradiating the coating film with light to impart liquid crystal aligning ability.
[5] A method for producing a liquid crystal element, comprising: a step of forming a coating film on each conductive film of a pair of substrates having a conductive film by using the liquid crystal aligning agent according to the above item [1]; a step of constructing a liquid crystal cell by disposing the pair of substrates on which the coating films have been formed so that the coating films face each other via a liquid crystal layer containing a photopolymerizable compound; and a step of irradiating the liquid crystal cell with light while a voltage is applied between the conductive films.
[6] A polymer having a heterocyclic structure (a) represented by the above formula (1-1), formula (1-2) or formula (1-3).
[7] A diamine represented by the following formula (2-1), formula (2-2) or formula (2-3):

In formula (2-1), Ar ¹ is a (p+2)-valent aromatic ring group. p is an integer from 1 to 4. r is 1 or 2. ^{X 11} is a single bond, -O-, -S-, -CO-, -COO-, -NR ³ -, -CO-NR ³ -, -CH ₂ -O-, -CH ₂ -CO- or -CH ₂ -OCO- when r is 1, and is a nitrogen atom or *-CO-N(-*) ₂ when r is 2. "*" represents a bond. R ¹ is a single bond, a divalent hydrocarbon group having 1 to 20 carbon atoms, a divalent group R ^k1 having 2 to 20 carbon atoms containing -O-, -S-, -CO-, -COO-, -NR ³ - or -CONR ³ - between the carbon-carbon bonds of the hydrocarbon group, or a divalent hydrocarbon group or a divalent group R is a group in which at least a part of the hydrogen atoms in ^k1 is replaced with a substituent. R ³ is a hydrogen atom or a monovalent organic group. ^{Y 11} is a divalent group having a heterocyclic structure (a) represented by the following formula (1-1), formula (1-2) or formula (1-3). R ² is a hydrogen atom or a monovalent organic group. When a plurality of X ¹¹ , R ¹ , Y ¹¹ , R ² and r are present in the formula, the plurality of X ¹¹ , R ¹ , Y ¹¹ , R ² and r are the same or different from each other.

(In formula (2-2), Ar ² and Ar ³ are each independently a divalent aromatic ring group. R ⁴ and R ⁵ are each independently a single bond or a divalent organic group. Y ¹² is a divalent group having a heterocyclic structure (a) represented by formula (1-1), formula (1-2) or formula (1-3) above. k is an integer of 0 to 3. When a plurality of Y ^{12 s} and R ^{5 s} are present in the formula, the plurality of Y ^{12 s} and R ^{5 s} are the same or different.)

(In formula (2-3), Ar ⁴ and Ar ⁵ are each independently a divalent aromatic ring group. R ⁶ is a trivalent organic group. X ¹² is a single bond, -O-, -S-, -CO-, -COO-, -NR ⁹ -, -CO-NR ⁹ -, -CH ₂ -O-, -CH ₂ -CO-, or -CH ₂ -OCO-. R ⁷ is a single bond, a divalent hydrocarbon group having 1 to 20 carbon atoms, a divalent group R k2 having 2 to 20 carbon atoms containing -O-, -S-, -CO-, -COO-, -NR ⁹ -, or -CO-NR ⁹ - between the carbon-carbon bonds of the hydrocarbon ^group , or a group in which at least a portion of the hydrogen atoms in the divalent hydrocarbon group or the divalent group R ^k2 are replaced with a substituent. R ⁹ is a hydrogen atom or a monovalent organic group. Y ^{R 13} is a divalent group having a heterocyclic structure (a) represented by the following formula (1-1), formula (1-2) or formula (1-3). R ⁸ is a hydrogen atom or a monovalent organic group.

The liquid crystal alignment agent of the present invention makes it possible to obtain a liquid crystal element with a high voltage retention rate and excellent reliability.

Liquid crystal alignment agent
The liquid crystal alignment agent of the present disclosure contains a compound [A] having a specific heterocyclic structure containing nitrogen and oxygen in the ring skeleton. Below, each component contained in the liquid crystal alignment agent of the present disclosure and other components that are optionally mixed as necessary will be described. Note that, unless otherwise specified, each component may be used alone or in combination of two or more.

Here, in this specification, the term "hydrocarbon group" includes chain-shaped hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. The term "chain-shaped hydrocarbon group" means a straight-chain hydrocarbon group and a branched hydrocarbon group that do not include a cyclic structure in the main chain and are composed only of a chain structure. However, the chain-shaped hydrocarbon group may be saturated or unsaturated. The term "alicyclic hydrocarbon group" means a hydrocarbon group that includes only an alicyclic hydrocarbon structure as a ring structure and does not include an aromatic ring structure. However, the alicyclic hydrocarbon group does not have to be composed only of an alicyclic hydrocarbon structure, and also includes those that have a chain structure as a part of it. The term "aromatic hydrocarbon group" means a hydrocarbon group that includes an aromatic ring structure as a ring structure. However, the aromatic hydrocarbon group does not have to be composed only of an aromatic ring structure, and may include a chain structure or an alicyclic hydrocarbon structure as a part of it. The term "aromatic ring" includes aromatic hydrocarbon rings and aromatic heterocycles. The term "organic group" means an atomic group obtained by removing any hydrogen atom from a compound containing carbon (i.e., an organic compound).

The "main chain" of a polymer refers to the "trunk" portion of the polymer, which is the longest chain of atoms. It is permissible for this "trunk" portion to contain a ring structure. For example, "having a specific structure in the main chain" means that the specific structure constitutes a part of the main chain. A "side chain" refers to a portion that branches off from the "trunk" portion of the polymer. "(Meth)acrylo" is a term that includes acrylo and methacrylo, and "(meth)acrylate" is a term that includes acrylate and methacrylate.

（式（１－１）～式（１－３）中、ｍ１及びｍ２は、それぞれ独立して１～３の整数である。Ｚ^１は単結合又はカルボニル基である。「＊」は結合手を表す。） <Compound [A]>
The compound [A] has a heterocyclic structure (a) represented by the following formula (1-1), formula (1-2) or formula (1-3).

(In formulas (1-1) to (1-3), m1 and m2 each independently represent an integer from 1 to 3. ^Z1 represents a single bond or a carbonyl group. "*" represents a bond.)

Compound [A] may be a polymer component or an additive component as long as it has the heterocyclic structure (a). The bonds represented by "*" in the above formulas (1-1) to (1-3) are not particularly limited to those to which they are bonded. That is, each bond represented by "*" may be bonded to an organic group or to a hydrogen atom. Specific examples of the heterocyclic structure (a) include structures in which n hydrogen atoms (n is an integer of 1 or more) have been removed from the heterocycles represented by the following formulas (1-a) to (1-g):

At least one of the multiple "*"s in each of the above formulas (1-1) to (1-3) is bonded to an aromatic hydrocarbon ring or aromatic heterocycle, so that the aromatic hydrocarbon ring or aromatic heterocycle is adjacent to the heterocycle structure (a). When an aromatic hydrocarbon ring or aromatic heterocycle is adjacent to the heterocycle structure (a), the radical generating ability of the heterocycle structure (a) associated with light absorption can be further improved, and the reliability and pretilt angle imparting characteristics of the liquid crystal element can be improved. Here, "pretilt angle imparting characteristics" refers to the property of imparting a stable pretilt angle to liquid crystal molecules by light irradiation or the like, and is a characteristic that is particularly required in PSA technology.

Specific examples of aromatic hydrocarbon rings include a benzene ring, a naphthalene ring, an anthracene ring, and the like. Examples of aromatic heterocycles include nitrogen-containing aromatic heterocycles such as a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, and an imidazole ring; oxygen-containing aromatic heterocycles such as a furan ring; and sulfur-containing aromatic heterocycles such as a thiophene ring. Among the above, the aromatic hydrocarbon ring or aromatic heterocycle adjacent to the ring in the heterocyclic structure (a) is preferably an aromatic hydrocarbon ring or a nitrogen-containing aromatic heterocycle, and more preferably a benzene ring, a naphthalene ring, or a pyridine ring.

The aromatic hydrocarbon ring or aromatic heterocycle adjacent to the ring in the heterocyclic structure (a) may have a substituent. Examples of the substituent include a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), a monovalent hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a monovalent halogenated hydrocarbon group having 1 to 20 carbon atoms, a halogenated alkoxy group having 1 to 20 carbon atoms, a hydroxyl group, a protected hydroxyl group, an amino group, a protected amino group, a nitro group, a cyano group, a carboxy group, a protected carboxy group, etc. In addition, the aromatic hydrocarbon ring or aromatic heterocycle bonded to the ring in the heterocyclic structure (a) may form a structure that imparts liquid crystal alignment to the film together with the substituent bonded to the aromatic hydrocarbon ring or aromatic heterocycle.

From the viewpoints of improving the reliability of the liquid crystal element and imparting a sufficient pretilt angle by light irradiation, m1 in the above formula (1-2) is preferably 1 or 2, and more preferably 1.
From the same viewpoint, m2 in the above formula (1-3) is preferably 1 or 2, and more preferably 1. ^Z1 is preferably a single bond.

It is considered that the heterocyclic structure (a) does not generate decomposition products even after decomposition due to light irradiation due to its basicity, and thus can improve the pretilt angle imparting characteristics while suppressing a decrease in voltage holding ratio and reliability. Among them, the structure represented by the above formula (1-2) or formula (1-3) is preferable, and the structure represented by the above formula (1-2) is more preferable, in terms of a high effect of improving the pretilt angle imparting characteristics. It is not clear why the structure represented by the above formula (1-2) or formula (1-3) has a high effect of improving the pretilt angle imparting characteristics, but one hypothesis is that it is due to the fact that in the above formula (1-2) or formula (1-3), radicals are generated in multiple stages upon light irradiation, and the amount of radicals generated is large (see the following scheme).

Specific embodiments of the liquid crystal aligning agent of the present disclosure containing the compound [A] include the following embodiments.
[1] A liquid crystal aligning agent containing a polymer having the heterocyclic structure (a) (hereinafter also referred to as the "first liquid crystal aligning agent")
[2] A liquid crystal aligning agent containing a polymer component and a compound having the heterocyclic structure (a) (excluding polymers) (hereinafter also referred to as the "second liquid crystal aligning agent").
The first liquid crystal alignment agent may further contain a compound having the heterocyclic structure (a) (excluding polymers). Among these, the above embodiment [1] is preferred in terms of the high effect of improving the pretilt angle imparting properties. The liquid crystal alignment agent of each embodiment will be specifically described below.

(First Liquid Crystal Alignment Agent)
The main chain of the polymer having the heterocyclic structure (a) (hereinafter also referred to as "polymer [A]") is not particularly limited. From the viewpoint of making the voltage holding property and liquid crystal alignment property of the obtained liquid crystal element excellent, the polymer [A] is preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane and addition polymer, more preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide and addition polymer, and even more preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester and polyimide. In addition, the polymer [A] may have the heterocyclic structure (a) in the main chain or in the side chain. In terms of being able to further enhance the effect of improving the voltage holding rate and reliability, and the effect of improving the pretilt angle imparting property, it is preferable that the polymer [A] has the heterocyclic structure (a) in the side chain. Each polymer will be described in detail below.

When polymer [A] is at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide, polymer [A] preferably has a structural unit derived from a diamine compound having a heterocyclic structure (a).

(Polyamic acid)
The polyamic acid as the polymer [A] (hereinafter, also referred to as “polyamic acid (A)”) can be obtained, for example, by reacting a tetracarboxylic dianhydride with a diamine compound.

Tetracarboxylic acid dianhydride Examples of the tetracarboxylic acid dianhydride used in the synthesis of the polyamic acid (A) include aliphatic tetracarboxylic acid dianhydrides and aromatic tetracarboxylic acid dianhydrides. The aliphatic tetracarboxylic acid dianhydrides include linear tetracarboxylic acid dianhydrides and alicyclic tetracarboxylic acid dianhydrides.

Specific examples of the chain tetracarboxylic dianhydride include butane tetracarboxylic dianhydride, etc. Specific examples of the alicyclic tetracarboxylic dianhydride include 1,2,3,4-cyclobutane tetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentyl acetic dianhydride, 5-(2,5-dioxotetrahydrofuran-3-yl)-3a,4,5,9b-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, 3-oxabicyclo[3.2.1]octane-2,4 ... 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2:3,5:6-dianhydride, bicyclo[3.3.0]octane-2,4,6,8-tetracarboxylic acid 2:4,6:8-dianhydride, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic acid 2:3,5:6-dianhydride, 4,9-dioxatricyclo[5.3.1.0 ^2,6 ]undecane-3,5,8,10-tetraone, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, ethylenediaminetetraacetic dianhydride, cyclopentanetetracarboxylic dianhydride, and the like.

Examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, p-phenylene bis(trimellitic monoester anhydride), ethylene glycol bis(anhydrotrimellitate), 1,3-propylene glycol bis(anhydrotrimellitate), 3,3',4,4'-benzophenone tetracarboxylic dianhydride, and 4,4'-biphthalic dianhydride. In addition to the above, the tetracarboxylic dianhydride described in JP-A-2010-97188 can be used as the tetracarboxylic dianhydride used in the synthesis of polyamic acid (A).

（式（２－１）中、Ａｒ^１は（ｐ＋２）価の芳香環基である。ｐは１～４の整数である。ｒは１又は２である。Ｘ^１１は、ｒが１の場合に、単結合、－Ｏ－、－Ｓ－、－ＣＯ－、－ＣＯＯ－、－ＮＲ^３－、－ＣＯ－ＮＲ^３－、－ＣＨ_２－Ｏ－、－ＣＨ_２－ＣＯ－又は－ＣＨ_２－ＯＣＯ－であり、ｒが２の場合に、窒素原子又は＊－ＣＯ－Ｎ（－＊）_２である。「＊」は結合手を表す。Ｒ^１は、単結合、炭素数１～２０の２価の炭化水素基、当該炭化水素基の炭素－炭素結合間に－Ｏ－、－Ｓ－、－ＣＯ－、－ＣＯＯ－、－ＮＲ^３－若しくは－ＣＯＮＲ^３－を含む炭素数２～２０の２価の基Ｒ^ｋ１、又は、２価の炭化水素基若しくは２価の基Ｒ^ｋ１における少なくとも一部の水素原子が置換基で置き換えられてなる基である。Ｒ^３は、水素原子又は１価の有機基である。Ｙ^１１は、下記式（１－１）、式（１－２）又は式（１－３）で表される複素環構造（ａ）を有する２価の基である。Ｒ^２は、水素原子又は１価の有機基である。式中にＸ^１１、Ｒ^１、Ｙ^１１、Ｒ^２、ｒが複数存在する場合、複数のＸ^１１、Ｒ^１、Ｙ^１１、Ｒ^２、ｒは互いに同一又は異なる。）

（式（２－２）中、Ａｒ^２及びＡｒ^３は、それぞれ独立して２価の芳香環基である。Ｒ^４及びＲ^５は、それぞれ独立して単結合又は２価の有機基である。Ｙ^１２は、複素環構造（ａ）を有する２価の基である。ｋは０～３の整数である。式中にＹ^１２、Ｒ^５が複数存在する場合、複数のＹ^１２、Ｒ^５は互いに同一又は異なる。）

（式（２－３）中、Ａｒ^４及びＡｒ^５は、それぞれ独立して２価の芳香環基である。Ｒ^６は３価の有機基である。Ｘ^１２は、単結合、－Ｏ－、－Ｓ－、－ＣＯ－、－ＣＯＯ－、－ＮＲ^９－、－ＣＯ－ＮＲ^９－、－ＣＨ_２－Ｏ－、－ＣＨ_２－ＣＯ－又は－ＣＨ_２－ＯＣＯ－である。Ｒ^７は、単結合、炭素数１～２０の２価の炭化水素基、当該炭化水素基の炭素－炭素結合間に－Ｏ－、－Ｓ－、－ＣＯ－、－ＣＯＯ－、－ＮＲ^９－若しくは－ＣＯ－ＮＲ^９－を含む炭素数２～２０の２価の基Ｒ^ｋ２、又は、２価の炭化水素基若しくは２価の基Ｒ^ｋ２における少なくとも一部の水素原子が置換基で置き換えられてなる基である。Ｒ^９は、水素原子又は１価の有機基である。Ｙ^１３は、下記式（１－１）、式（１－２）又は式（１－３）で表される複素環構造（ａ）を有する２価の基である。Ｒ^８は、水素原子又は１価の有機基である。） Diamine Compounds In the synthesis of polyamic acid (A), a diamine having a heterocyclic structure (a) (hereinafter also referred to as a "specific diamine") can be preferably used. The specific diamine only needs to have a partial structure represented by the above formula (1-1), formula (1-2) or formula (1-3), and the structure of the other parts is not particularly limited. Preferable specific examples of the specific diamine include a compound represented by the following formula (2-1), a compound represented by the following formula (2-2), and a compound represented by the following formula (2-3).

In formula (2-1), Ar ¹ is a (p+2)-valent aromatic ring group. p is an integer from 1 to 4. r is 1 or 2. ^{X 11} is a single bond, -O-, -S-, -CO-, -COO-, -NR ³ -, -CO-NR ³ -, -CH ₂ -O-, -CH ₂ -CO- or -CH ₂ -OCO- when r is 1, and is a nitrogen atom or *-CO-N(-*) ₂ when r is 2. "*" represents a bond. R ¹ is a single bond, a divalent hydrocarbon group having 1 to 20 carbon atoms, a divalent group R ^k1 having 2 to 20 carbon atoms containing -O-, -S-, -CO-, -COO-, -NR ³ - or -CONR ³ - between the carbon-carbon bonds of the hydrocarbon group, or a divalent hydrocarbon group or a divalent group R is a group in which at least a part of the hydrogen atoms in ^k1 is replaced with a substituent. R ³ is a hydrogen atom or a monovalent organic group. ^{Y 11} is a divalent group having a heterocyclic structure (a) represented by the following formula (1-1), formula (1-2) or formula (1-3). R ² is a hydrogen atom or a monovalent organic group. When a plurality of X ¹¹ , R ¹ , Y ¹¹ , R ² and r are present in the formula, the plurality of X ¹¹ , R ¹ , Y ¹¹ , R ² and r are the same or different from each other.

(In formula (2-2), Ar ² and Ar ³ are each independently a divalent aromatic ring group. R ⁴ and R ⁵ are each independently a single bond or a divalent organic group. ^{Y 12} is a divalent group having a heterocyclic structure (a). k is an integer of 0 to 3. When a plurality of Y ¹² and R ⁵ are present in the formula, the plurality of Y ¹² and R ⁵ are the same or different.)

(In formula (2-3), Ar ⁴ and Ar ⁵ are each independently a divalent aromatic ring group. R ⁶ is a trivalent organic group. X ¹² is a single bond, -O-, -S-, -CO-, -COO-, -NR ⁹ -, -CO-NR ⁹ -, -CH ₂ -O-, -CH ₂ -CO-, or -CH ₂ -OCO-. R ⁷ is a single bond, a divalent hydrocarbon group having 1 to 20 carbon atoms, a divalent group R k2 having 2 to 20 carbon atoms containing -O-, -S-, -CO-, -COO-, -NR ⁹ -, or -CO-NR ⁹ - between the carbon-carbon bonds of the hydrocarbon ^group , or a group in which at least a portion of the hydrogen atoms in the divalent hydrocarbon group or the divalent group R ^k2 are replaced with a substituent. R ⁹ is a hydrogen atom or a monovalent organic group. Y ^{R 13} is a divalent group having a heterocyclic structure (a) represented by the following formula (1-1), formula (1-2) or formula (1-3). R ⁸ is a hydrogen atom or a monovalent organic group.

In the above formulas (2-1) to (2-3), the aromatic ring group represented by Ar ¹ , Ar ² , Ar ³ , Ar ⁴ or Ar ⁵ is a group obtained by removing t hydrogen atoms (in the case of Ar ¹ , t is an integer of 3 to 6, and in the case of Ar ² , Ar ³ , Ar ⁴ or Ar ⁵ , t is 2) from an aromatic ring. Examples of the aromatic ring include the same rings as those exemplified above as the aromatic hydrocarbon ring or aromatic heterocycle. Among these, an aromatic hydrocarbon ring or a nitrogen-containing heterocycle is preferred, and a benzene ring, a naphthalene ring or a pyridine ring is more preferred. The aromatic ring group represented by Ar ¹ , Ar ² , Ar ³ , Ar ⁴ or Ar ⁵ may have a substituent on the ring portion. Specific examples of the substituent include the groups exemplified as the substituent that the aromatic hydrocarbon ring or aromatic heterocycle adjacent to the heterocyclic structure (a) may have.

When the group represented by ^R3 or ^R9 is a monovalent organic group, examples of the organic group include a monovalent hydrocarbon group having 1 to 10 carbon atoms and a monovalent thermally detachable group. Examples of the monovalent thermally detachable group include a tert-butoxycarbonyl group (Boc group), a benzyloxycarbonyl group, a 1,1-dimethyl-2-haloethyloxycarbonyl group, an allyloxycarbonyl group, a 2-(trimethylsilyl)ethoxycarbonyl group, and a 9-fluorenylmethyloxycarbonyl group. Among these, the Boc group is particularly preferred in that it has excellent thermal detachment properties and can reduce the amount of the detached structure remaining in the film.

When r is 2, X ¹¹ is a nitrogen atom or *-CO-N(-*) _2. In this case, the specific diamine represented by the above formula (2-1) has a structure in which two groups "-R ¹ -Y ¹¹ -R ² " are bonded to a nitrogen atom.

When the group represented by R ¹ or R ⁷ is a divalent hydrocarbon group or divalent group (R ^k1 , R ^k2 ) having 1 to 20 carbon atoms, specific examples of the hydrocarbon group include a chain hydrocarbon group having 1 to 20 carbon atoms (however, in the case of the divalent group (R ^k1 , R ^k2 ), a chain hydrocarbon group having 2 to 20 carbon atoms), an alicyclic hydrocarbon group having 3 to 20 carbon atoms, and an aromatic hydrocarbon group having 6 to 20 carbon atoms. When at least a part of the hydrogen atoms in the divalent hydrocarbon group or the divalent group (R ^k1 , R ^k2 ) is replaced with a substituent, examples of the substituent include the groups exemplified as the substituent that may be possessed by the aromatic hydrocarbon ring or aromatic heterocycle adjacent to the heterocyclic structure (a). In addition, the divalent organic group represented by R ¹ or R ⁷ may have a photoalignment site such as a cinnamate structure, a carbene structure, or an azobenzene structure.

When the group represented by R ² or R ⁸ is a monovalent organic group, examples of the monovalent organic group include a monovalent hydrocarbon group having 1 to 30 carbon atoms, a monovalent group having 2 to 30 carbon atoms containing -O-, -S-, -CO-, -COO-, -NR ¹¹ - or -CO-NR ¹¹ - between the carbon-carbon bonds of the hydrocarbon group (hereinafter also referred to as "monovalent group R ^k3 "), and a group in which at least a part of the hydrogen atoms in the monovalent hydrocarbon group or the monovalent group R ^k3 is replaced with a substituent. In R ² or R ⁸ , the hydrocarbon group may be any of a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. R ¹¹ is a hydrogen atom or a monovalent organic group, and examples of the monovalent organic group include the same groups as those exemplified as the groups represented by R ³ or R ^9. Examples of the substituent include the groups exemplified as the substituents that the aromatic hydrocarbon ring or aromatic heterocycle adjacent to the heterocyclic structure (a) may have.

The monovalent organic group represented by ^R2 or ^R8 may have a photoalignment site such as a cinnamate structure, a carbene structure, or an azobenzene structure, or may have a structure capable of imparting a pretilt angle to a liquid crystal alignment film without light irradiation (for example, a linear alkylene structure having 4 to 20 carbon atoms, a halogenated linear alkylene structure having 4 to 20 carbon atoms, a structure in which an alkyl group having 2 to 20 carbon atoms, an alkoxy group having 2 to 20 carbon atoms, a halogenated alkyl group having 2 to 20 carbon atoms, a halogenated alkoxy group having 2 to 20 carbon atoms, a halogen atom, or a cyano group is bonded to a benzene ring or a cyclohexane ring, a structure in which two or more of one or more rings among benzene rings and cyclohexane rings are bonded via a single bond or a linking group, a steroid structure, etc.).

From the viewpoint of further enhancing the radical generating ability by light absorption, obtaining a liquid crystal element with excellent reliability, and sufficiently enhancing the pretilt angle imparting property, one or both of R ¹ and R ² in the above formula (2-1) are preferably bonded to Y ¹¹ via an aromatic hydrocarbon ring or aromatic heterocycle, and more preferably bonded to Y ¹¹ via a benzene ring, a naphthalene ring, or a pyridine ring. From the same viewpoint, one or both of R ⁷ and R ⁸ in the above formula (2-2) are preferably bonded to Y ^{13 via an aromatic hydrocarbon ring or aromatic heterocycle, and more preferably bonded to Y 13 via} a benzene ring, a naphthalene ring, or a pyridine ring.

Y ¹¹ , Y ¹² and Y ¹³ each have a heterocyclic structure represented by the above formula (1-1), formula (1-2) or formula (1-3). For example, in the compound represented by the above formula (2-1), two bonds in the above formula (1-1) are each bonded to R ¹ or R ² in the above formula (2-1), any two bonds among the [(m1×2)+2] bonds in the above formula (1-2) are each bonded to R ¹ or R ² in the above formula (2-1), and any two bonds among the [(m2×2)+2] bonds in the above formula (1-3) are each bonded to R ¹ or R ² in the above formula (2-1).

When the group represented by R ⁴ or R ⁵ is a divalent organic group, the divalent organic group may be a divalent hydrocarbon group having 1 to 20 carbon atoms, a divalent group having 2 to 20 carbon atoms containing -O-, -S-, -CO-, -COO-, -NR ¹⁰ - or -CO-NR ¹⁰ - between the carbon-carbon bonds of the hydrocarbon group (hereinafter also referred to as "divalent group R ^k4 "), a group in which at least a part of the hydrogen atoms in the divalent hydrocarbon group or the divalent group R ^k4 is replaced with a substituent, or the like. The hydrocarbon group in R ⁴ or R ⁵ may be any of a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. R ¹⁰ is a hydrogen atom or a monovalent organic group, and examples of the monovalent organic group include the same groups as those exemplified as the groups represented by R ³ or R ^9. Examples of the substituent include the groups exemplified as the substituents that the aromatic hydrocarbon ring or aromatic heterocycle adjacent to the heterocyclic structure (a) may have.

Specific examples of the specific diamine include compounds represented by the following formulae (DA-1) to (DA-28), in which "Boc" represents a tert-butoxycarbonyl group (hereinafter the same).

The specific diamine can be synthesized by appropriately combining standard methods in organic chemistry. One example is a method in which a dinitro compound having a nitro group instead of the primary amino group in the specific diamine is synthesized, and then the nitro group of the resulting dinitro compound is aminated using an appropriate reduction system.

The method for synthesizing the dinitro form can be appropriately selected depending on the target compound. For example, the dinitro form (DA-1-1) for obtaining the compound represented by the above formula (DA-1) can be obtained according to the following scheme 1. Furthermore, the dinitro form (DA-2-1) for obtaining the compound represented by the above formula (DA-2) can be obtained according to the following scheme 2.

The reduction reaction of the dinitro compound can be preferably carried out in an organic solvent using a catalyst such as palladium on carbon, platinum on carbon, zinc, iron, tin, or nickel. Examples of the organic solvent used here include ethyl acetate, toluene, tetrahydrofuran, and alcohols. However, the synthesis procedure for the specific diamine is not limited to the above method.

The diamine compound used in the synthesis of polyamic acid (A) may be the specific diamine alone. In addition, the diamine compound used in the synthesis of polyamic acid (A) may be a combination of the specific diamine and a diamine not having a heterocyclic structure (a) (hereinafter also referred to as "other diamine").

Other diamines include, for example, aliphatic diamines, aromatic diamines, diaminoorganosiloxanes, etc. Aliphatic diamines include linear diamines and alicyclic diamines.

（式（Ｅ－１）中、Ｘ^I及びＸ^IIは、それぞれ独立して、単結合、－Ｏ－、＊－ＣＯＯ－又は＊－ＯＣＯ－（ただし、「＊」はジアミノフェニル基側との結合手を表す）である。Ｒ^Ｉは、炭素数１～３のアルカンジイル基である。Ｒ^ＩＩは、単結合又は炭素数１～３のアルカンジイル基である。Ｒ^ＩＩＩは、炭素数１～２０のアルキル基、アルコキシ基、フルオロアルキル基又はフルオロアルコキシ基である。ａは０又は１である。ｂは０～３の整数である。ｃは０～２の整数である。ｄは０又は１である。ただし、１≦ａ＋ｂ＋ｃ≦３である。）
で表される化合物などの配向性基含有ジアミン：
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’－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、１，２－ビス（４－アミノフェノキシ）エタン、１，２－ビス（４－アミノフェノキシ）エタン、１，３－ビス（４－アミノフェノキシ）プロパン、１，５－ビス（４－アミノフェノキシ）ペンタン、１，６－ビス（４－アミノフェノキシ）ヘキサン、１，７－ビス（４－アミノフェノキシ）ヘプタン、ビス［２－（４－アミノフェニル）エチル］ヘキサン二酸、Ｎ，Ｎ－ビス（４－アミノフェニル）メチルアミン、Ｎ，Ｎ’－ジ（５－アミノ－２－ピリジル）－Ｎ，Ｎ’－ジ（ｔｅｒｔ－ブトキシカルボニル）エチレンジアミン、４，４’－（２，２’－オキシビス（エタン－２，１－ジイル）ビス（オキシ））ジアニリン、１，５－ジアミノナフタレン、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、９，９－ビス（４－アミノフェニル）フルオレン、２，２－ビス［４－（４－アミノフェノキシ）フェニル］ヘキサフルオロプロパン、２，２－ビス（４－アミノフェニル）ヘキサフルオロプロパン、４，４’－（ｐ－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’－ビス（４－アミノフェノキシ）ビフェニル、２，６－ジアミノピリジン、２，４－ジアミノピリミジン、３，６－ジアミノアクリジン、３，６－ジアミノカルバゾール、Ｎ－メチル－３，６－ジアミノカルバゾール、Ｎ，Ｎ’－ビス（４－アミノフェニル）－ベンジジン、Ｎ，Ｎ’－ビス（４－アミノフェニル）－Ｎ，Ｎ’－ジメチルベンジジン、１，４－ビス－（４－アミノフェニル）－ピペラジン、３，５－ジアミノ安息香酸、１－（４－アミノフェノキシ）－２－（４－（４’－アミノフェニル）フェノキシ）エタン、３，５－ジアミノ－Ｎ，Ｎ－ビス（ピリジン－３－イルメチル）ベンズアミド、下記式（ｆ－１）～式（ｆ－３４）

のそれぞれで表されるジアミン等を；
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を用いることができる。ポリアミック酸（Ａ）の合成に使用するその他のジアミンとしては、１種を単独で又は２種以上を適宜選択して使用することができる。 Specific examples of other diamines include chain diamines such as m-xylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, and 1,3-bis(aminomethyl)cyclohexane; alicyclic diamines such as 1,4-diaminocyclohexane and 4,4'-methylenebis(cyclohexylamine);
Examples of aromatic diamines include dodecanoxydiaminobenzene, tetradecanoxydiaminobenzene, pentadecanoxydiaminobenzene, hexadecananoxydiaminobenzene, octadecanoxydiaminobenzene, cholestanyloxydiaminobenzene, cholesteryloxydiaminobenzene, cholestanyl diaminobenzoate, cholesteryl diaminobenzoate, lanostannyl diaminobenzoate, 3,6-bis(4-aminobenzoyloxy)cholestane, 3,6-bis(4-aminophenoxy)cholestane, 1 , 1-bis(4-((aminophenyl)methyl)phenyl)-4-butylcyclohexane, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-heptylcyclohexane, 1,1-bis(4-((aminophenoxy)methyl)phenyl)-4-heptylcyclohexane, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-(4-heptylcyclohexyl)cyclohexane, N-(2,4-diaminophenyl)-4-(4-heptylcyclohexyl)benzamide, and compounds represented by the following formula (E-1):

(In formula (E-1), X ^I and X ^II are each independently a single bond, -O-, *-COO-, or *-OCO- (wherein "*" represents a bond to the diaminophenyl group). R ^I is an alkanediyl group having 1 to 3 carbon atoms. R ^II is a single bond or an alkanediyl group having 1 to 3 carbon atoms. R ^III is an alkyl group, alkoxy group, fluoroalkyl group, or fluoroalkoxy group having 1 to 20 carbon atoms. a is 0 or 1. b is an integer of 0 to 3. c is an integer of 0 to 2. d is 0 or 1, with the proviso that 1≦a+b+c≦3.)
Orienting group-containing diamines such as compounds represented by the formula:
p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylamine, 4,4'-diaminodiphenyl sulfide, 4-aminophenyl-4'-aminobenzoate, 4,4'-diaminoazobenzene, 1,2-bis(4-aminophenoxy)ethane, 1,2-bis(4-aminophenoxy)ethane, 1,3-bis(4-aminophenoxy)propane, 1,5-bis(4-aminophenoxy)pentane, 1,6-bis(4-aminophenoxy)hexane, 1,7-bis(4-aminophenoxy) ) heptane, bis[2-(4-aminophenyl)ethyl]hexanedioic acid, N,N-bis(4-aminophenyl)methylamine, N,N'-di(5-amino-2-pyridyl)-N,N'-di(tert-butoxycarbonyl)ethylenediamine, 4,4'-(2,2'-oxybis(ethane-2,1-diyl)bis(oxy))dianiline, 1,5-diaminonaphthalene, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl nyl ether, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 9,9-bis(4-aminophenyl)fluorene, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-(p-phenylenediisopropylidene)bisaniline, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 2,6-diaminopyridine, 2,4-diaminopyrimidine, 3,6- Diaminoacridine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, N,N'-bis(4-aminophenyl)-benzidine, N,N'-bis(4-aminophenyl)-N,N'-dimethylbenzidine, 1,4-bis-(4-aminophenyl)-piperazine, 3,5-diaminobenzoic acid, 1-(4-aminophenoxy)-2-(4-(4'-aminophenyl)phenoxy)ethane, 3,5-diamino-N,N-bis(pyridin-3-ylmethyl)benzamide, and the compounds represented by the following formulae (f-1) to (f-34):

Diamines represented by the following formula:
Examples of diaminoorganosiloxanes include 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, and the like. Diamines described in JP-A-2010-97188 can also be used. As the other diamines used in the synthesis of the polyamic acid (A), one type can be used alone, or two or more types can be appropriately selected and used.

The divalent group represented by "-X ^I -(R ^I -X ^II ) _d -" in the above formula (E-1) is preferably an alkanediyl group having 1 to 3 carbon atoms, *-O-, *-COO-, or *-O-C ₂ H ₄ -O- (wherein the bond marked with "*" is bonded to the diaminophenyl group). The group represented by R ^III is preferably linear. The two amino groups in the diaminophenyl group are preferably in the 2,4-position or 3,5-position relative to other groups.

Specific examples of the compound represented by formula (E-1) above include the compounds represented by formulas (E-1-1) to (E-1-4) below.

In the synthesis of polyamic acid (A), the proportion of the specific diamine used is preferably 1 mol% or more, more preferably 5 mol% or more, and even more preferably 10 mol% or more, based on the total amount of the diamine compounds used in the synthesis of polyamic acid (A). When the proportion of the specific diamine used is within the above range, it is preferable in that the effect of improving the voltage retention rate, reliability, and pretilt angle imparting characteristics of the liquid crystal element can be sufficiently obtained. In addition, in the synthesis of polyamic acid (A), the proportion of the specific diamine used may be 100 mol% or less, based on the total amount of the diamine compounds used in the synthesis of polyamic acid (A). When the desired characteristics are imparted by using other diamines, the proportion of the specific diamine used is preferably 95 mol% or less, more preferably 70 mol% or less, based on the total amount of the diamine compounds used in the synthesis of polyamic acid (A).

(Synthesis of polyamic acid)
The polyamic acid (A) can be obtained by reacting the above-mentioned tetracarboxylic dianhydride with a diamine compound, optionally together with a molecular weight modifier. The ratio of the tetracarboxylic dianhydride and the diamine compound used in the synthesis reaction of the polyamic acid (A) is preferably such that the amount of the acid anhydride group of the tetracarboxylic dianhydride is 0.2 to 2 equivalents, more preferably 0.3 to 1.2 equivalents, per equivalent of the amino group of the diamine compound.

Examples of molecular weight regulators include acid monoanhydrides such as maleic anhydride, phthalic anhydride, and itaconic anhydride; monoamine compounds such as aniline, cyclohexylamine, and n-butylamine; and monoisocyanate compounds such as phenyl isocyanate and naphthyl isocyanate. The proportion of the molecular weight regulator used is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of the total of the tetracarboxylic dianhydride and diamine compounds used.

The synthesis reaction of polyamic acid (A) is preferably carried out in an organic solvent. The reaction temperature is preferably -20°C to 150°C, more preferably 0 to 100°C. The reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours.

Examples of organic solvents used in the reaction include aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons. Of these organic solvents, it is preferable to use one or more selected from the group consisting of aprotic polar solvents and phenolic solvents (first group organic solvents), or a mixture of one or more selected from the first group organic solvents and one or more selected from the group consisting of alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons (second group organic solvents). In the latter case, the proportion of the second group organic solvent used is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, based on the total amount of the first group organic solvents and the second group organic solvents.

Particularly preferred organic solvents are one or more selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethylsulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide, m-cresol, xylenol and halogenated phenols, or a mixture of one or more of these with other organic solvents in the above ratio range. The amount of organic solvent (x) used is preferably an amount such that the total amount (y) of the tetracarboxylic dianhydride and the diamine compound is 0.1 to 50% by mass relative to the total amount (x+y) of the reaction solution.

In this manner, a reaction solution in which polyamic acid (A) is dissolved is obtained. This reaction solution may be used as it is for the preparation of a liquid crystal alignment agent, or the polyamic acid (A) contained in the reaction solution may be isolated and then used for the preparation of a liquid crystal alignment agent, or the isolated polyamic acid (A) may be purified and then used for the preparation of a liquid crystal alignment agent. When polyamic acid (A) is dehydrated and cyclized to form a polyimide, the reaction solution may be used as it is for the dehydration and cyclization reaction, or the polyamic acid (A) contained in the reaction solution may be isolated and then used for the dehydration and cyclization reaction, or the isolated polyamic acid (A) may be purified and then used for the dehydration and cyclization reaction. Isolation and purification of polyamic acid (A) can be performed according to a known method.

(Polyamic acid ester)
The polyamic acid ester as the polymer [A] can be obtained, for example, by a method such as [I] reacting the polyamic acid (A) obtained by the above-mentioned synthesis reaction with an esterifying agent, [II] reacting a tetracarboxylic acid diester with a diamine compound, or [III] reacting a tetracarboxylic acid diester dihalide with a diamine compound.

In this specification, "tetracarboxylic acid diester" refers to a compound in which two of the four carboxy groups in a tetracarboxylic acid are esterified and the remaining two are carboxy groups. "Tetracarboxylic acid diester dihalide" refers to a compound in which two of the four carboxy groups in a tetracarboxylic acid are esterified and the remaining two are halogenated.

Examples of the esterification agent used in the method [I] include hydroxyl group-containing compounds, acetal compounds, halides, and epoxy group-containing compounds. Specific examples of these include hydroxyl group-containing compounds such as alcohols, such as methanol, ethanol, and propanol, and phenols, such as phenol and cresol; acetal compounds such as N,N-dimethylformamide diethyl acetal and N,N-diethylformamide diethyl acetal; halides such as methyl bromide, ethyl bromide, stearyl bromide, methyl chloride, stearyl chloride, and 1,1,1-trifluoro-2-iodoethane; and epoxy group-containing compounds such as propylene oxide.

The tetracarboxylic acid diester used in the method [II] can be obtained by ring-opening the tetracarboxylic acid dianhydride exemplified in the explanation of the synthesis of polyamic acid (A) using an alcohol such as methanol or ethanol. The tetracarboxylic acid derivative used in the method [II] may be only the tetracarboxylic acid diester, or may be used in combination with a tetracarboxylic acid dianhydride. As for the diamine compound, the specific diamine exemplified in the synthesis of polyamic acid may be used alone, or may be used in combination with other diamines.

The reaction in method [II] is preferably carried out in an organic solvent in the presence of a suitable dehydration catalyst. Examples of the organic solvent include those exemplified as those used in the synthesis of polyamic acid (A). Examples of the dehydration catalyst include 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium halide, carbonylimidazole, and phosphorus-based condensing agents. The reaction temperature in this case is preferably -20 to 150°C, and more preferably 0 to 100°C. The reaction time is preferably 0.1 to 24 hours, and more preferably 0.5 to 12 hours.

The tetracarboxylic acid diester dihalide used in the method [III] can be obtained, for example, by reacting the tetracarboxylic acid diester obtained as described above with a suitable chlorinating agent such as thionyl chloride. The tetracarboxylic acid derivative used in the method [III] may be only the tetracarboxylic acid diester dihalide, but may also be used in combination with a tetracarboxylic acid dianhydride. As for the diamine compound, the specific diamines exemplified in the explanation of the synthesis of the polyamic acid (A) may be used alone or in combination with other diamines.

The reaction in method [III] is preferably carried out in an organic solvent in the presence of a suitable base. Examples of the organic solvent include those exemplified as those used in the synthesis of polyamic acid (A). Examples of the base that can be preferably used include tertiary amines such as pyridine and triethylamine; and alkali metals such as sodium hydride, potassium hydride, sodium hydroxide, potassium hydroxide, sodium, and potassium. The reaction temperature is preferably -20 to 150°C, and more preferably 0 to 100°C. The reaction time is preferably 0.1 to 24 hours, and more preferably 0.5 to 12 hours.

The polyamic acid ester contained in the liquid crystal aligning agent may have only an amic acid ester structure, or may be a partially esterified product in which an amic acid structure and an amic acid ester structure coexist. The reaction solution in which the polyamic acid ester is dissolved may be used for the preparation of the liquid crystal aligning agent as it is, or the polyamic acid ester contained in the reaction solution may be isolated and then used for the preparation of the liquid crystal aligning agent, or the isolated polyamic acid ester may be purified and then used for the preparation of the liquid crystal aligning agent. The isolation and purification of the polyamic acid ester may be carried out according to a known method.

(Polyimide)
The polyimide as the polymer [A] can be obtained, for example, by subjecting the polyamic acid (A) synthesized as described above to dehydration ring-closure to imidization.

The polyimide may be a fully imidized product in which all of the amic acid structures of the polyamic acid precursor have been dehydrated and cyclically closed, or a partially imidized product in which only a portion of the amic acid structures have been dehydrated and cyclically closed, resulting in both amic acid structures and imide ring structures. The polyimide used in the reaction preferably has an imidization rate of 20% or more, more preferably 30 to 99%, and even more preferably 40 to 99%. This imidization rate is the ratio, expressed as a percentage, of the number of imide ring structures to the total number of amic acid structures and imide ring structures of the polyimide. Here, some of the imide rings may be isoimide rings.

The dehydration and ring-closing of the polyamic acid is preferably carried out by heating the polyamic acid, or by dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydration and ring-closing catalyst to the solution, and heating as necessary.

In the method of adding a dehydrating agent and a dehydration ring-closing catalyst to a solution of polyamic acid, the dehydrating agent may be, for example, an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride. The amount of the dehydrating agent used is preferably 0.01 to 20 moles per mole of the amic acid structure of the polyamic acid. The dehydration ring-closing catalyst may be, for example, a tertiary amine such as pyridine, collidine, lutidine, triethylamine, or 1-methylpiperidine. The amount of the dehydration ring-closing catalyst used is preferably 0.01 to 10 moles per mole of the dehydrating agent used. Examples of organic solvents used in the dehydration ring-closing reaction include the organic solvents exemplified as those used in the synthesis of polyamic acid. The reaction temperature of the dehydration ring-closing reaction is preferably 0 to 180°C, more preferably 10 to 150°C. The reaction time is preferably 1.0 to 120 hours, more preferably 2.0 to 30 hours.

In this way, a reaction solution containing polyimide is obtained. This reaction solution may be used as it is for the preparation of a liquid crystal alignment agent, or the dehydrating agent and the dehydration ring-closing catalyst may be removed from the reaction solution before use for the preparation of a liquid crystal alignment agent, or the polyimide may be isolated before use for the preparation of a liquid crystal alignment agent, or the isolated polyimide may be purified before use for the preparation of a liquid crystal alignment agent. These purification operations can be carried out according to known methods. In addition, polyimide can also be obtained by imidizing polyamic acid ester.

The polyamic acid, polyamic acid ester, and polyimide as polymer [A] obtained in the above manner preferably have a solution viscosity of 20 to 1,800 mPa·s, and more preferably 50 to 1,500 mPa·s, when made into a 15% by mass solution. The solution viscosity (mPa·s) of the polymer is the value measured at 25°C using an E-type rotational viscometer for a 15% by mass polymer solution prepared using a good solvent for the polymer (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

The polystyrene-equivalent weight average molecular weight (Mw) of the polyamic acid, polyamic acid ester, and polyimide as polymer [A] measured by gel permeation chromatography (GPC) is preferably 1,000 to 500,000, more preferably 2,000 to 300,000. The molecular weight distribution (Mw/Mn) of the polyamic acid, polyamic acid ester, and polyimide as polymer [A], expressed as the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) measured by GPC, is preferably 8 or less, more preferably 5 or less. When the Mw and Mw/Mn of the polyamic acid, polyamic acid ester, and polyimide as polymer [A] are within the above ranges, good liquid crystal alignment properties of the liquid crystal element can be ensured.

（式（３－１）中、Ｒ^２１は、水素原子又はメチル基である。Ｘ^１は、－ＣＯＯ－、－ＣＯＮＨ－又は２価の芳香環基である。Ｘ^２は単結合又は２価の有機基である。Ａ^１は、複素環構造（ａ）を有する２価の基である。Ｙ^１は１価の有機基である。
式（３－２）中、Ｒ^２２及びＲ^２３は、それぞれ独立して水素原子又はメチル基である。Ｘ^３は２価の有機基である。Ａ^２は、複素環構造（ａ）を有する２価の基である。Ｙ^２は１価の有機基である。） (Addition polymer)
The addition polymer as the polymer [A] (hereinafter also referred to as “addition polymer (A)”) preferably has at least one selected from the group consisting of a structural unit represented by the following formula (3-1) and a structural unit represented by the following formula (3-2):

(In formula (3-1), R ²¹ is a hydrogen atom or a methyl group. X ¹ is —COO—, —CONH— or a divalent aromatic ring group. X ² is a single bond or a divalent organic group. ^{A 1} is a divalent group having a heterocyclic structure (a). Y ¹ is a monovalent organic group.
In formula (3-2), R ²² and R ²³ are each independently a hydrogen atom or a methyl group. X ³ is a divalent organic group. A ² is a divalent group having a heterocyclic structure (a). Y ² is a monovalent organic group.

In the above formulas (3-1) and (3-2), when the group represented by ^X1 is a divalent aromatic ring group, the divalent aromatic ring group is preferably a group in which two hydrogen atoms have been removed from a benzene ring or a naphthalene ring. The ring constituting the aromatic ring group may have a substituent. Examples of the substituent include the groups exemplified as the substituent that may be possessed by the aromatic hydrocarbon ring or aromatic heterocycle adjacent to the heterocyclic structure (a).

Examples of the divalent organic group represented by ^X2 or ^X3 include the same groups as those exemplified when the group represented by ^R4 or ^R5 is a divalent organic group. Examples of the monovalent organic group represented by ^Y1 or ^Y2 include the same groups as those exemplified when the group represented by ^R2 or ^R8 is a monovalent organic group.

Specific examples of the monomer that provides the structural unit represented by the formula (3-1) include the compounds represented by the following formulas (MA-3) to (MA-10). Specific examples of the monomer that provides the structural unit represented by the formula (3-2) include the compounds represented by the following formulas (MA-1) and (MA-2).

When synthesizing the addition polymer (A), a monomer not having a heterocyclic structure (a) (hereinafter also referred to as "other monomer") may be used in combination. Examples of other monomers include (meth)acrylic compounds, styrene compounds, conjugated diene compounds, maleimide compounds, etc.

Specific examples of other monomers include (meth)acrylic compounds, such as unsaturated carboxylic acids such as (meth)acrylic acid; unsaturated carboxylic acid esters such as alkyl (meth)acrylates (e.g., methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc.), cycloalkyl (meth)acrylates, benzyl (meth)acrylate, trimethoxysilylpropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxybutyl (meth)acrylate, 4-hydroxybutyl glycidyl ether (meth)acrylate, 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, 6-(meth)acryloyloxyhexyltrimethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane.

Examples of aromatic vinyl compounds include styrene, methylstyrene, divinylbenzene, 4-hydroxymethylstyrene, p-styryltrimethoxysilane, 4-(glycidyloxymethyl)styrene, and vinylbenzoic acid. Examples of conjugated diene compounds include 1,3-butadiene and 2-methyl-1,3-butadiene. Examples of maleimide compounds include N-methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-(4-glycidyloxyphenyl)maleimide, and N-glycidylmaleimide.

As other monomers, compounds other than those mentioned above may be used, such as photoalignable groups (for example, cinnamate structures, coumarin structures, and azobenzene structures), alkyl groups having 4 to 30 carbon atoms, halogenated alkyl groups having 4 to 30 carbon atoms, alkoxy groups having 4 to 30 carbon atoms, halogenated alkoxy groups having 4 to 30 carbon atoms, structures in which two or more of one or more of the rings selected from the group consisting of benzene rings and cyclohexane rings are linked via a single bond or a linking group, or unsaturated monomers having a group having a steroid skeleton. When synthesizing the addition polymer (A), one type of other monomer may be used alone, or two or more types may be used in combination.

The addition polymer (A) can be obtained, for example, by polymerizing monomers in the presence of a polymerization initiator. The polymerization initiator used is preferably an azo compound such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), or 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile). The proportion of the polymerization initiator used is preferably 0.01 to 30 parts by mass relative to 100 parts by mass of the total monomers used in the reaction.

The polymerization reaction is preferably carried out in an organic solvent. Examples of organic solvents used in the reaction include alcohols, ethers, ketones, amides, esters, and hydrocarbon compounds, and diethylene glycol ethyl methyl ether and propylene glycol monomethyl ether acetate are preferred. The reaction temperature is preferably 30°C to 120°C, and the reaction time is preferably 1 to 36 hours. The amount of organic solvent used is preferably such that the total amount of monomers used in the reaction is 0.1 to 60% by mass relative to the total amount of the reaction solution. The addition polymer (A) can also be obtained by a method in which an addition polymer having an epoxy group in the side chain is synthesized, and then the obtained epoxy group-containing addition polymer is reacted with a carboxylic acid having a heterocyclic structure (a) (hereinafter also referred to as a "specific carboxylic acid").

The polystyrene-equivalent weight average molecular weight (Mw) of the addition polymer (A) measured by GPC is preferably 250 to 500,000, and more preferably 500 to 100,000. The molecular weight distribution (Mw/Mn), which is expressed as the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) measured by GPC, is preferably 8 or less, and more preferably 6 or less.

(Polyorganosiloxane)
The method for producing the polyorganosiloxane as the polymer [A] (hereinafter also referred to as "polyorganosiloxane (A)") is not particularly limited as long as a polymer having a heterocyclic structure (a) can be obtained. Specifically, the following methods [1s] and [2s] can be mentioned.

[1s] A method in which a hydrolyzable silane compound (ms-1) having an epoxy group, or a mixture of the silane compound (ms-1) and another silane compound, is hydrolyzed and condensed to synthesize an epoxy group-containing polyorganosiloxane, and then the resulting epoxy group-containing polyorganosiloxane is reacted with a carboxylic acid having a heterocyclic structure (a) (hereinafter also referred to as a "specific carboxylic acid").
[2s] A method of hydrolyzing and condensing a hydrolyzable silane compound (ms-2) having a heterocyclic structure (a) or a mixture of the silane compound (ms-2) with another silane compound.
Among these, the method (1s) is preferable because it is simple and easy and can increase the introduction rate of the heterocyclic structure (a) in the polyorganosiloxane (A).

Specific examples of silane compounds (ms-1) include, for example, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethylmethyldimethoxysilane, 2-glycidoxyethyldimethylmethoxysilane, 2-glycidoxyethyldimethylethoxysilane, 4-glycidoxybutyltrimethoxysilane, 4-glycidoxybutylmethyldimethoxysilane, 4-glycidoxybutylmethyldiethoxysilane, 4-glycidoxybutyldimethylmethoxysilane, 4-glycidoxybutyldimethylethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-(3,4-epoxycyclohexyl)propyltrimethoxysilane, and the like. As the silane compound (ms-1), one of these can be used alone or two or more can be used in combination.

The other silane compounds used in the synthesis of the epoxy group-containing polyorganosiloxane are not particularly limited as long as they are hydrolyzable silane compounds.Specific examples thereof include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane, and dimethyldiethoxysilane;
Nitrogen- or sulfur-atom-containing alkoxysilanes, such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, mercaptomethyltrimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(3-cyclohexylamino)propyltrimethoxysilane, and N-2-(aminoethyl)-3-aminopropyltrimethoxysilane;
Examples of the other silane compounds include unsaturated hydrocarbon-containing alkoxysilanes such as 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, 6-(meth)acryloyloxyhexyltrimethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and p-styryltrimethoxysilane; trimethoxysilylpropylsuccinic anhydride, etc. As the other silane compounds, one type can be used alone, or two or more types can be used in combination.

The hydrolysis and condensation reaction of the silane compounds can be carried out by reacting one or more of the above silane compounds with water, preferably in the presence of a suitable catalyst and an organic solvent. In the reaction, the proportion of water used is preferably 1 to 30 moles per mole of the silane compounds (total amount). Examples of the catalyst used include acids, alkali metal compounds, organic bases, titanium compounds, zirconium compounds, etc. The amount of the catalyst used varies depending on the type of catalyst, reaction conditions such as temperature, etc., and can be set appropriately. The amount of the catalyst used is preferably 0.01 to 3 moles per total amount of the silane compounds. Examples of the organic solvent used include hydrocarbons, ketones, esters, ethers, alcohols, etc. Among these, it is preferable to use a water-insoluble or poorly water-soluble organic solvent. The proportion of the organic solvent used is preferably 10 to 10,000 parts by mass per 100 parts by mass of the total silane compounds used in the reaction.

The above hydrolysis and condensation reaction is preferably carried out by heating, for example, in an oil bath. In this case, the heating temperature is preferably 130°C or less, and the heating time is preferably 0.5 to 12 hours. After the reaction is completed, the organic solvent layer separated from the reaction solution is dried with a desiccant as necessary, and the solvent is then removed to obtain the desired polyorganosiloxane. Note that the method for synthesizing polyorganosiloxane is not limited to the above hydrolysis and condensation reaction, and may also be carried out, for example, by a method in which a hydrolyzable silane compound is reacted in the presence of oxalic acid and alcohol.

In the above method [1s], the epoxy group-containing polyorganosiloxane obtained by the above reaction is then reacted with a specific carboxylic acid. This causes the epoxy group of the epoxy group-containing polyorganosiloxane to react with the carboxyl group of the specific carboxylic acid, thereby obtaining polyorganosiloxane (A) having a heterocyclic structure (a) in its side chain.

Specific examples of the specific carboxylic acid include compounds represented by the following formula (CA-1) or formula (CA-2).

The content of the heterocyclic structure (a) in one molecule of polyorganosiloxane (A) is preferably 1 mol% or more, more preferably 2 mol% or more, and even more preferably 5 mol% or more, based on the silicon atoms contained in polyorganosiloxane (A). The content of the heterocyclic structure (a) in one molecule of polyorganosiloxane (A) is preferably 70 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less, based on the silicon atoms contained in polyorganosiloxane (A). The content of the heterocyclic structure (a) in polyorganosiloxane (A) in the above range is preferable in that it is possible to sufficiently obtain the effect of improving the reliability and pretilt angle imparting characteristics of the liquid crystal element while suppressing the decrease in the voltage holding ratio.

In addition, when synthesizing polyorganosiloxane (A), the carboxylic acid used in the reaction with the epoxy group-containing polyorganosiloxane may be only the specific carboxylic acid, but a carboxylic acid not having a heterocyclic structure (a) (hereinafter also referred to as "other carboxylic acid") may be used in combination. Examples of other carboxylic acids include photoalignment groups (for example, cinnamate structures, coumarin structures, and azobenzene structures), alkyl groups having 4 to 30 carbon atoms, halogenated alkyl groups having 4 to 30 carbon atoms, alkoxy groups having 4 to 30 carbon atoms, halogenated alkoxy groups having 4 to 30 carbon atoms, structures in which one or more rings of benzene rings and cyclohexane rings are linked via single bonds or linking groups, or carboxylic acids having a group having a steroid skeleton other than the above compounds.

The reaction between the epoxy group-containing polyorganosiloxane and the carboxylic acid can be preferably carried out in the presence of a catalyst and an organic solvent. Examples of the catalyst that can be used include organic bases and compounds known as so-called curing accelerators that accelerate the reaction of epoxy compounds (e.g., tertiary organic amines, quaternary organic amines, quaternary ammonium salts, etc.). The amount of catalyst used is preferably 100 parts by mass or less, more preferably 0.1 to 20 parts by mass, per 100 parts by mass of the epoxy group-containing polyorganosiloxane.

Examples of organic solvents used in the above reaction include hydrocarbons, ethers, esters, ketones, amides, and alcohols. The organic solvent is preferably used in a proportion such that the solids concentration (the proportion of the total mass of the components other than the solvent in the reaction solution to the total weight of the solution) is 0.1 mass% or more, and more preferably 5 to 50 mass%. In the above reaction, the reaction temperature is preferably 0 to 200°C, more preferably 50 to 150°C. The reaction time is preferably 0.1 to 50 hours, more preferably 0.5 to 20 hours. After the reaction is completed, it is preferable to wash the organic solvent layer separated from the reaction solution with water. After washing with water, the organic solvent layer is dried with an appropriate desiccant as necessary, and then the solvent is removed to obtain the target polyorganosiloxane (A).

When the polyorganosiloxane (A) is dissolved in a solution having a concentration of 10% by mass, it preferably has a solution viscosity of 1 to 500 mPa·s, and more preferably has a solution viscosity of 3 to 200 mPa·s. The weight average molecular weight (Mw) of the polyorganosiloxane (A) measured by GPC in terms of polystyrene is preferably 1,000 to 200,000, more preferably 2,000 to 50,000, and even more preferably 3,000 to 20,000.

The content ratio of polymer [A] in the liquid crystal alignment agent of the present disclosure is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, per 100 parts by mass of the solid content (components other than the solvent of the liquid crystal alignment agent) contained in the liquid crystal alignment agent.

(Other ingredients)
The first liquid crystal aligning agent may contain components other than the polymer [A] (hereinafter, also referred to as “other components”).

Polymer [B]
The liquid crystal aligning agent of the present disclosure may further contain a polymer not having a heterocyclic structure (a) (hereinafter also referred to as "polymer [B]"). Polymer [B] can be used for the purpose of suppressing a decrease in voltage holding ratio, improving liquid crystal alignment, etc.

The main skeleton of polymer [B] is not particularly limited, but examples thereof include polyamic acid, polyimide, polyamic acid ester, polyorganosiloxane, polyester, cellulose derivative, polyacetal, and addition polymer. Examples of addition polymers include styrene-based polymers, (meth)acrylic polymers, maleimide-based polymers, and styrene-maleimide copolymers. Of these, polymer [B] is preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane, and addition polymer. As the monomer constituting polymer [B], known monomers can be used, and examples thereof include the above-mentioned monomers that do not have a heterocyclic structure (a).

When used as a liquid crystal alignment agent for photoalignment treatment, the polymer [A] may contain a photosensitive polymer and the polymer [B] may contain a non-photosensitive polymer. Alternatively, the polymer [A] may contain a non-photosensitive polymer and the polymer [B] may contain a photosensitive polymer. In addition, both the polymer [A] and the polymer [B] may contain a photosensitive polymer.

When polymer [B] is contained in the first liquid crystal alignment agent, the content ratio of polymer [B] is preferably 95 parts by mass or less, and more preferably 90 parts by mass or less, per 100 parts by mass of the polymer components contained in the liquid crystal alignment agent (i.e., the total amount of polymer [A] and polymer [B]).

Compound having heterocyclic structure (a) The liquid crystal aligning agent of the present disclosure may further contain a compound having a heterocyclic structure (a) (excluding the polymer [A]. Hereinafter, also referred to as "compound (A)"). The compound (A) is, for example, a low molecular weight compound having a molecular weight of 1,000 or less, and may have a molecular weight of 800 or less. The compound (A) may have only one heterocyclic structure (a), or may have two or more heterocyclic structures (a). From the viewpoint of improving the reliability of the liquid crystal element and allowing the pretilt angle to be sufficiently imparted by light irradiation, the compound (A) preferably has two or more heterocyclic structures (a), more preferably has 2 to 6 heterocyclic structures (a).

As the compound (A), a compound having a crosslinkable group can be preferably used in terms of increasing the reliability of the liquid crystal element. Examples of the crosslinkable group include a cyclic ether group, a cyclic thioether group, an isocyanate group, a protected isocyanate group, a methylol group, a protected methylol group, a hydroxyalkylamide group, a cyclic carbonate group, a group having a polymerizable carbon-carbon bond, a group "-CR ³⁰ ═CR ³¹ -R ³² -" (wherein R ³⁰ is a monovalent organic group that is eliminated by reaction with an amino group. R ³¹ is a hydrogen atom or an alkyl group, and R ³² is an electron-withdrawing group), a silanol group, and an alkoxysilyl group. From the viewpoint of maintaining a good balance between reactivity and storage stability, among these, a compound having at least two or more of at least one selected from the group consisting of a cyclic ether group, a protected isocyanate group, a methylol group, a protected methylol group, a hydroxyalkylamide group, and a cyclic carbonate group in the molecule can be preferably used. The number of crosslinkable groups contained in the compound (A) is preferably 2 to 10, and more preferably 2 to 6.

Specific examples of the compound (A) include the compounds represented by the following formulas (ADA-1) to (ADA-7).

When compound (A) is contained in the first liquid crystal alignment agent, the content ratio of compound (A) is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the polymer components (total amount of polymer [A] and polymer [B]) contained in the liquid crystal alignment agent. In addition, the content ratio of compound (A) is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, per 100 parts by mass of the polymer components contained in the liquid crystal alignment agent.

Crosslinking Agent The liquid crystal alignment agent of the present disclosure may further contain a crosslinking agent. By including a crosslinking agent, the crosslinking reaction of the polymer component can be promoted during the formation of the liquid crystal alignment film, and the mechanical properties and the adhesion to the substrate and the sealant can be improved. Examples of the crosslinking agent include a compound (A) having a crosslinkable group; a crosslinkable compound not having a heterocyclic structure (a) (hereinafter also referred to as "compound (C)"); and the like. Specific examples of the crosslinkable group possessed by the compound (C) include the same groups as the groups exemplified as the crosslinkable group that may be possessed by the compound (A). The number of crosslinkable groups possessed by the compound (C) is preferably 2 to 10, more preferably 2 to 6.

Specific examples of the compound (C) include compounds represented by the following formulas.

When the crosslinking agent is contained in the first liquid crystal alignment agent, the content ratio of the crosslinking agent (i.e., the total amount of compound (A) and compound (C)) is preferably 1 part by mass or more, and more preferably 3 parts by mass or more, per 100 parts by mass of the polymer components (the total amount of polymer [A] and polymer [B]) contained in the liquid crystal alignment agent. The content ratio of the crosslinking agent is preferably 30 parts by mass or less, and more preferably 25 parts by mass or less, per 100 parts by mass of the polymer components contained in the liquid crystal alignment agent. Note that one type of crosslinking agent may be used alone, or two or more types may be used in combination.

Solvent The first liquid crystal aligning agent is preferably prepared as a liquid composition in which the polymer [A] and any other components used as required are dispersed or dissolved in a suitable solvent.

Examples of organic solvents that can be used include N-methyl-2-pyrrolidone, 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, ethylene 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 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 combination of two or more.

Other components include, in addition to those mentioned above, functional silane compounds, antioxidants, metal chelate compounds, curing accelerators, surfactants, fillers, dispersants, photosensitizers, etc. The blending ratio of these can be appropriately selected according to each compound within a range that does not impair the effects of the present disclosure.

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 taking into consideration the viscosity, volatility, etc., but is preferably in the range of 1 to 10 mass%. That is, the liquid crystal alignment agent is applied to the surface of the substrate as described below, and preferably heated to form a coating film that is a liquid crystal alignment film or a coating film that will become a liquid crystal alignment film. By setting the solid content concentration of the liquid crystal alignment agent to 1 mass% or more, the thickness of the coating film can be sufficiently ensured, and a good liquid crystal alignment film tends to be easily obtained. In addition, by setting the solid content concentration of the liquid crystal alignment agent to 10 mass% or less, the thickness of the coating film does not become too large, and an increase in the viscosity of the liquid crystal alignment agent can be suppressed, and the coatability tends to be good.

The particularly preferred range of solid content varies depending on the application of the liquid crystal alignment agent and the method used to apply the liquid crystal alignment agent to the substrate. For example, when applying a liquid crystal alignment agent for a liquid crystal display element to a substrate by a spinner method, it is particularly preferred that the solid content concentration (the ratio of the total mass of all components other than the solvent in the liquid crystal alignment agent to the total mass of the liquid crystal alignment agent) is in the range of 1.5 to 4.5 mass%. When using the printing method, it is particularly preferred that the solid content concentration is in the range of 3 to 9 mass%, thereby making the solution viscosity in the range of 12 to 50 mPa·s. When using the inkjet method, it is particularly preferred that the solid content concentration is in the range of 1 to 5 mass%, thereby making the solution viscosity in the range of 3 to 15 mPa·s. The temperature when preparing the liquid crystal alignment agent is preferably 10 to 50°C, more preferably 20 to 30°C. In addition, for liquid crystal alignment agents for retardation films, from the viewpoint of the applicability of the liquid crystal alignment agent and the appropriate thickness of the coating film formed, the solid content concentration of the liquid crystal alignment agent is preferably in the range of 0.2 to 10% by mass, and more preferably in the range of 3 to 10% by mass.

(Second Liquid Crystal Alignment Agent)
The second liquid crystal alignment agent contains a polymer component and a compound (A). The polymer component contained in the second liquid crystal alignment agent includes the polymer exemplified as the polymer [B] described above. The polymer component contained in the second liquid crystal alignment agent is preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane, and addition polymer. In addition, a known monomer can be used as the monomer constituting the polymer component, and for example, a monomer not having a heterocyclic structure (a) among the above-mentioned monomers can be mentioned.

Examples of the compound (A) include the same compounds as those exemplified as the compound (A) that may be incorporated into the first liquid crystal alignment agent. Compounds having a crosslinkable group can be preferably used as the compound (A).

The content of compound (A) is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, relative to 100 parts by mass of the polymer component contained in the liquid crystal alignment agent. The content of compound (A) is preferably 30 parts by mass or less, and more preferably 25 parts by mass or less, relative to 100 parts by mass of the polymer component contained in the liquid crystal alignment agent. Compound (A) may be used alone or in combination of two or more types.

The second liquid crystal alignment agent may further contain a component different from the polymer component and the compound (A). Specific examples of such components include the same compounds as those exemplified as other components that may be blended into the first liquid crystal alignment agent.

<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. 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 liquid crystal operation mode in the liquid crystal element can be applied to various modes such as, 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 PSA (Polymer Sustained Alignment) type. The liquid crystal alignment agent of the present disclosure is particularly suitable as a liquid crystal alignment agent for the PSA mode among the above, in that it can provide a stable pretilt angle by light irradiation treatment in the manufacturing process of the liquid crystal element.

Liquid crystal elements can be manufactured, for example, by a method including the following steps 1 to 3. In step 1, the substrate used varies depending on the desired operating mode. Steps 2 and 3 are common to all operating modes.

(Step 1: Formation of coating film)
First, a liquid crystal alignment agent is applied onto a substrate, and the applied surface is preferably heated to form a coating film on the substrate. As the substrate, for example, a transparent substrate made of glass such as float glass or soda glass, or plastic such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, or poly(alicyclic olefin) can be used. The transparent conductive film provided on one side of the substrate may be a NESA film (registered trademark of PPG, USA) made of tin oxide (SnO ₂ ), or an ITO film made of indium oxide-tin oxide (In ₂ O ₃ -SnO ₂ ). When manufacturing a TN-type, STN-type, VA-type or PSA-type liquid crystal element, two substrates each having a patterned transparent conductive film are used. On the other hand, when manufacturing an IPS-type or FFS-type liquid crystal element, a substrate having an electrode made of a transparent conductive film or metal film patterned into a comb-tooth shape and an opposing substrate having no electrode are used. As the metal film, for example, a film made of a metal such as chromium can be used. The liquid crystal alignment agent is preferably applied to the substrate on the electrode-forming surface by offset printing, spin coating, roll coating or inkjet printing.

After the liquid crystal alignment agent is applied, pre-heating (pre-baking) is preferably performed to prevent dripping of the applied liquid crystal alignment agent. The pre-baking temperature is preferably 30 to 200°C, and the pre-baking time is preferably 0.25 to 10 minutes. Thereafter, if necessary, a baking (post-baking) process is performed to completely remove the solvent or to thermally imidize the amic acid structure present in the polymer. The baking 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. After the liquid crystal alignment agent is applied to the substrate, the organic solvent is removed to form a liquid crystal alignment film or a coating film that will become a liquid crystal alignment film.

(Step 2: Alignment Treatment)
When manufacturing a TN type, STN type, IPS type or FFS type liquid crystal element, a treatment (alignment treatment) is carried out to impart liquid crystal alignment ability to the coating film formed in step 1. As a result, the alignment ability of liquid crystal molecules is imparted to the coating film to form a liquid crystal alignment film. Examples of the alignment treatment include a rubbing treatment in which the surface of the coating film formed on the substrate is rubbed with cotton or the like, and a photo-alignment treatment in which the coating film is irradiated with light to impart liquid crystal alignment ability. In particular, the liquid crystal alignment agent of the present disclosure can be preferably applied as a photo-alignment agent that imparts liquid crystal alignment ability by subjecting a coating film formed using the liquid crystal alignment agent to a light irradiation treatment. On the other hand, when manufacturing a vertical alignment type (VA type) liquid crystal element, the coating film formed in step 1 can be used as it is as a liquid crystal alignment film, but the coating film may be subjected to an alignment treatment. A liquid crystal alignment film suitable for a vertical alignment type liquid crystal element can also be preferably used for a PSA type liquid crystal element.

The light irradiation in the photo-alignment treatment can be performed by a method of irradiating the coating film after the post-bake step, a method of irradiating the coating film after the pre-bake step but before the post-bake step, or a method of irradiating the coating film while it is being heated in at least one of the pre-bake step and the post-bake step. In the photo-alignment treatment, the radiation to be irradiated to the coating film can be, for example, ultraviolet light and visible light containing light with a wavelength of 150 to 800 nm. Preferably, ultraviolet light containing light with a wavelength of 200 to 400 nm. When the radiation is polarized, it may be linearly polarized or partially polarized. When the radiation used is linearly polarized or partially polarized, the radiation may be performed from a direction perpendicular to the substrate surface, from an oblique direction, or a combination of these. When non-polarized radiation is irradiated, the direction of irradiation is oblique.

Examples of light sources that can be used include low-pressure mercury lamps, high-pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonance lamps, xenon lamps, excimer lasers, etc. The radiation dose is preferably 400 to 20,000 J/ ^m2 , and more preferably 1,000 to 5,000 J/ ^m2 . The coating film may be irradiated with light while being heated in order to increase the reactivity.

When manufacturing a liquid crystal alignment film, the coating film that has been subjected to light irradiation treatment may be heated within a temperature range of 120°C to 280°C. This type of heating treatment is preferable in that it further improves the liquid crystal alignment (thermal realignment) and results in a liquid crystal element with improved display quality. This heating may be post-baking, or may be a heating treatment that is performed separately from post-baking and after post-baking. When performing the heating treatment on the coating film that has been subjected to light irradiation treatment, the heating temperature is preferably 140°C or higher, and more preferably 150°C to 250°C, from the viewpoint of promoting the realignment of molecular chains by heating. The heating time is preferably 5 to 200 minutes, more preferably 10 to 60 minutes.

The manufacturing of the liquid crystal alignment film may further include a step of contacting the coating film that has been 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. 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. Of these, the solvent used in this step is preferably water, isopropanol, or a mixture thereof. Examples of the method of contacting the coating film with the solvent include, but are not limited to, spraying, showering, immersion, and puddling. The contact time between the coating film and the solvent is not particularly limited, but is, for example, 5 seconds to 15 minutes. After contact with the solvent, the coating film may be subjected to a heat treatment.

(Step 3: Construction of liquid crystal cell)
Two substrates on which the liquid crystal alignment film is formed as described above are prepared, and a liquid crystal is disposed between the two substrates arranged opposite to each other to manufacture a liquid crystal cell. For example, the liquid crystal cell can be manufactured by (1) arranging two substrates opposite to each other through a gap (spacer) so that the liquid crystal alignment film faces each other, bonding the peripheries of the two substrates with a sealant, injecting liquid crystal into the cell gap partitioned by the substrate surface and the sealant, and then sealing the injection hole, or (2) applying a sealant to a predetermined location on one substrate on which the liquid crystal alignment film is formed, dropping liquid crystal at a few predetermined locations on the liquid crystal alignment film surface, bonding the other substrate so that the liquid crystal alignment film faces each other, and spreading the liquid crystal over the entire surface of the substrate (ODF method). It is preferable to further heat the manufactured liquid crystal cell to a temperature at which the liquid crystal used has an isotropic phase, and then slowly cool it to room temperature to remove the flow orientation during liquid crystal filling.

As the sealing agent, for example, an epoxy resin containing a hardener and aluminum oxide spheres as a spacer can be used. As the spacer, a photospacer, a bead spacer, etc. can be used. As the liquid crystal, nematic liquid crystal and smectic liquid crystal can be mentioned. Among these, nematic liquid crystal is preferable, and for example, Schiff base liquid crystal, azoxy liquid crystal, biphenyl liquid crystal, phenylcyclohexane liquid crystal, ester liquid crystal, terphenyl liquid crystal, biphenylcyclohexane liquid crystal, pyrimidine liquid crystal, dioxane liquid crystal, bicyclooctane liquid crystal, cubane liquid crystal, etc. can be used. In addition, cholesteric liquid crystal, chiral agent, ferroelectric liquid crystal, etc. may be added to these liquid crystals.

In the PSA mode, a photopolymerizable compound is filled into the cell gap together with liquid crystal, and after the liquid crystal cell is constructed, a process of irradiating the liquid crystal cell with light is performed while a voltage is applied between the conductive films of a pair of substrates. That is, it is preferable to manufacture a liquid crystal element by a method including the following steps.
[1] A step of forming a coating film using a liquid crystal alignment agent on each of the conductive films of a pair of substrates having a conductive film (corresponding to the above step 1).
[2] A step of constructing a liquid crystal cell by disposing a pair of substrates on which the coating film has been formed so that the coating films face each other via a liquid crystal layer containing a photopolymerizable compound (corresponding to the above step 3).
[3] A step of irradiating the liquid crystal cell with light while applying a voltage between the conductive films.

As the photopolymerizable compound, a polyfunctional compound having two or more radically polymerizable functional groups such as an acryloyl group, a (meth)acryloyl group, a vinyl group, etc. can be preferably used. From the viewpoint of reactivity, the photopolymerizable compound is preferably a polyfunctional (meth)acrylic compound having two or more (meth)acryloyl groups. In addition, from the viewpoint of stably maintaining the alignment of the liquid crystal molecules, a compound having a total of two or more rings of at least one of a cyclohexane ring and a benzene ring as the liquid crystal skeleton can be preferably used as the photopolymerizable compound. Note that, as such a photopolymerizable compound, a conventionally known compound can be used. When manufacturing a PSA type liquid crystal element, the proportion of the photopolymerizable compound used is, for example, 0.01 to 3 parts by mass, preferably 0.05 to 1 part by mass, relative to 100 parts by mass of the liquid crystal.

The voltage applied can be, for example, 5 to 50 V DC or AC. As the light to be irradiated, for example, ultraviolet light and visible light containing light with a wavelength of 150 to 800 nm can be used, and ultraviolet light containing light with a wavelength of 300 to 400 nm is preferred. As the light source for the irradiation light, 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 excimer laser, etc. can be used. The amount of light irradiation is preferably 1,000 to 200,000 J/ ^m2 or less, more preferably 1,000 to 100,000 J/ ^m2 .

Next, if necessary, a polarizing plate is attached to the outer surface of the liquid crystal cell. Examples of polarizing plates include a polarizing film called an "H film" made by stretching and aligning polyvinyl alcohol and absorbing iodine, sandwiched between cellulose acetate protective films, or a polarizing plate made of the H film itself.

The liquid crystal element of the present disclosure can be effectively applied to various applications, for example, in various display devices such as watches, portable game machines, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, liquid crystal televisions, and information displays, as well as in light control films. In addition, the liquid crystal element formed using the liquid crystal alignment agent of the present disclosure can also be applied to retardation films.

According to the present disclosure described above, the following means are provided.
[Means 1] A liquid crystal aligning agent containing a compound [A] having a heterocyclic structure (a) represented by the above formula (1-1), formula (1-2) or formula (1-3).
[Means 2] The liquid crystal aligning agent according to [Means 1], wherein an aromatic hydrocarbon ring or an aromatic heterocycle is bonded to the heterocyclic structure (a).
[Means 3] The liquid crystal aligning agent according to [Means 1] or [Means 2], wherein the compound [A] is a polymer having the heterocyclic structure (a).
[Means 4] The liquid crystal aligning agent according to [Means 3], wherein the polymer is at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane, and addition polymer.
[Means 5] The liquid crystal aligning agent according to [Means 3] or [Means 4], wherein the polymer has the heterocyclic structure (a) in a side chain.
[Means 6]
The liquid crystal aligning agent according to [means 3] or [means 4], wherein the polymer has the heterocyclic structure (a) in a main chain.
[Measure 7] The liquid crystal aligning agent according to any one of [Measure 3] to [Measure 6], wherein the polymer has a structural unit derived from a diamine compound having the heterocyclic structure (a).
[Means 8] The polymer has at least one selected from the group consisting of a structural unit represented by the above formula (3-1) and a structural unit represented by the above formula (3-2). A liquid crystal aligning agent according to any one of [Means 3] to [Means 5].
[Means 9] The liquid crystal aligning agent according to [Means 1] or [Means 2], wherein the compound [A] is a low molecular weight compound having a molecular weight of 1,000 or less.
[Means 10] The liquid crystal aligning agent according to [Means 9], wherein the compound [A] has a crosslinkable group.
[Means 11] The liquid crystal aligning agent according to any one of [Means 1] to [Means 10], further comprising a polymer not having the heterocyclic structure (a).
[Means 12] The liquid crystal aligning agent according to any one of [Means 1] to [Means 11], further comprising a crosslinkable compound not having the heterocyclic structure (a).
[Means 13] A liquid crystal alignment film formed by using the liquid crystal aligning agent according to any one of [Means 1] to [Means 12].
[Means 14] A method for producing a liquid crystal alignment film, comprising: forming a coating film using the liquid crystal alignment agent according to any one of [Means 1] to [Means 12]; and irradiating the coating film with light to impart liquid crystal alignment ability.
[Means 15] A method for producing a liquid crystal element, comprising: forming a coating film on each conductive film of a pair of substrates having a conductive film by using the liquid crystal aligning agent according to any one of [Means 1] to [Means 12]; constructing a liquid crystal cell by disposing the pair of substrates on which the coating films have been formed so that the coating films face each other via a liquid crystal layer containing a photopolymerizable compound; and irradiating the liquid crystal cell with light while a voltage is applied between the conductive films.
[Means 16] A liquid crystal element comprising the liquid crystal alignment film according to [Means 13].
[Means 17] A polymer having a heterocyclic structure (a) represented by the above formula (1-1), formula (1-2) or formula (1-3).
[Means 18] A diamine represented by the above formula (2-1), formula (2-2) or formula (2-3).

The present invention will be explained in more detail below with reference to examples, but the present invention should not be construed as being limited to the following examples.

In the following examples, the imidization rate of polyimide in a polymer solution was measured by the following method.
[Imidization rate of polyimide]
The polyimide solution was poured into pure water, and the resulting precipitate was thoroughly dried under reduced pressure at room temperature, then dissolved in deuterated dimethyl sulfoxide and subjected to ^1H -NMR measurement at room temperature using tetramethylsilane as a standard substance. From the obtained ^1H -NMR spectrum, the imidization rate [%] was calculated using the following formula (1).
Imidization rate [%] = (1 - (A ¹ / (A ² × α))) × 100 ... (1)
(In formula (1), ^A1 is the peak area due to the proton of the NH group appearing at a chemical shift of about 10 ppm. ^A2 is the peak area due to other protons. α is the ratio of the number of other protons to one proton of the NH group in the polymer precursor (polyamic acid).)

The necessary amounts of the raw material compounds and polymers used in the following examples were obtained by repeating the synthesis on the scale shown in the synthesis examples below as necessary. Note that "parts" and "%" in the examples and comparative examples are by weight unless otherwise specified.

The abbreviations for the compounds are as follows. In the following, the compound represented by formula (X) may be simply referred to as "compound (X)."

(Tetracarboxylic acid dianhydride)

(Diamine Compound)

(Polymerizable unsaturated monomer, siloxane monomer, carboxylic acid)

(Additive)

<Synthesis of Polymer>
1. Synthesis of polyamic acid [Synthesis Example 1]
As tetracarboxylic dianhydrides, 80 parts by mole of compound (T-1), 10 parts by mole of compound (T-6), and 10 parts by mole of compound (T-9), as well as 10 parts by mole of compound (DA-1), 70 parts by mole of compound (D-24), and 20 parts by mole of compound (D-12) as diamine compounds were dissolved in N-methyl-2-pyrrolidone (NMP) and reacted at 60° C. for 6 hours to obtain a solution containing 20% by mass of polyamic acid (referred to as polymer (PI-1)).

[Synthesis Examples 3, 7 to 10, 12 to 16, 18 to 21, 23 to 26, 28, 29, 31 to 33]
The same operation as in Synthesis Example 1 was carried out except that the types and amounts of the tetracarboxylic dianhydrides and diamine compounds used were changed as shown in Table 1, to obtain polyamic acids (polymers (PI-3), (PI-7) to (PI-10), (PI-12) to (PI-16), (PI-18) to (PI-21), (PI-23) to (PI-26), (PI-28), (PI-29), and (PI-31) to (PI-33). In Table 1, the numerical values of the tetracarboxylic dianhydrides (acid dianhydrides 1 to 3) represent the ratio (molar ratio) of each compound relative to 100 parts by mole of the total amount of the tetracarboxylic dianhydrides used in the synthesis of the polymer. The numerical values of the diamine compounds (diamines 1 to 4) represent the ratio (molar ratio) of each compound relative to 100 parts by mole of the total amount of the diamine compounds used in the synthesis of the polymer.

2. Synthesis of polyimide [Synthesis Example 2]
As tetracarboxylic dianhydrides, 70 mol parts of compound (T-2) and 30 mol parts of compound (T-3), as well as 30 mol parts of compound (DA-6), 30 mol parts of compound (D-12), 25 mol parts of compound (D-15), and 15 mol parts of compound (D-24) as diamine compounds were dissolved in NMP, and the reaction was carried out at 60 ° C. for 6 hours to obtain a solution containing 20 mass % of polyamic acid. Next, NMP was added to the obtained polyamic acid solution to obtain a solution with a polyamic acid concentration of 10 mass %, and pyridine and acetic anhydride were added to carry out a dehydration ring-closing reaction at 80 ° C. for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with fresh NMP to obtain a solution containing 15 mass % of polyimide (this is referred to as polymer (PI-2)) with an imidization rate of about 40%.

[Synthesis Examples 4 to 6, 11, 17, 22, 27, and 30]
The same operations as in Synthesis Example 2 were carried out except that the types and amounts of the tetracarboxylic dianhydrides and diamine compounds used were changed as shown in Table 1, thereby obtaining polyimides (polymers (PI-4) to (PI-6), (PI-11), (PI-17), (PI-22), (PI-27), and (PI-30)).

3. Synthesis of styrene-maleimide copolymer [Synthesis Example 34]
Under nitrogen, a 100 mL two-neck flask was charged with 20 mol parts of compound (MA-1), 10 mol parts of compound (M-5), 20 mol parts of compound (M-7), 10 mol parts of compound (M-8), 40 mol parts of compound (M-9), 0.3922 g of 2,2'-azobis (2,4-dimethylvaleronitrile) as a radical polymerization initiator (10 parts by mass relative to 100 parts by mass of the total amount of polymerization monomers), and 15.68 g of N-methyl-2-pyrrolidone (NMP) as a solvent (400 parts by mass relative to 100 parts by mass of the total amount of polymerization monomers), and polymerized at 70 ° C. for 6 hours. After reprecipitation in methanol, the precipitate was filtered and dried in vacuum at room temperature for 8 hours to obtain the desired addition polymer (this is referred to as polymer (PM-1)).

[Synthesis Examples 35 to 44]
The same procedure as in Synthesis Example 34 was carried out except that the types and amounts of the polymerization monomers used were changed as shown in Table 2, to obtain addition polymers (polymers (PM-2) to (PM-11)).

4. Synthesis of polyorganosiloxane [Synthesis Example 45]
In a 1000 mL three-neck flask, 100.0 g of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (compound (S-1)), 500 g of methyl isobutyl ketone, and 10.0 g of triethylamine were charged and mixed at room temperature. Next, 100 g of deionized water was dropped from the dropping funnel over 30 minutes, and then the reaction was carried out at 80 ° C. for 6 hours while mixing under reflux. After the reaction was completed, the organic layer was taken out and washed with a 0.2 mass% aqueous ammonium nitrate solution until the water after washing became neutral, and then the solvent and water were distilled off under reduced pressure. An appropriate amount of methyl isobutyl ketone was added to obtain a 50 mass% solution of polymer (ESSQ-1), which is a polyorganosiloxane having an epoxy group.
In a 500 mL three-neck flask, 15 mol% of the compound (CA-1) with respect to the amount of epoxy groups in the polymer (ESSQ-1), 15 mol% of the compound (C-1) with respect to the amount of epoxy groups in the polymer (ESSQ-1), 1.00 g of tetrabutylammonium bromide, 20.0 g of the polymer (ESSQ-1)-containing solution, and 290.0 g of methyl isobutyl ketone were added and stirred at 90 ° C. for 18 hours. After cooling to room temperature, the separation and washing operation was repeated 10 times with distilled water. Thereafter, the organic layer was collected, concentrated and diluted with NMP twice using a rotary evaporator, and then the solid content concentration was adjusted to 10% by mass using NMP to obtain an NMP solution of polyorganosiloxane (this is polymer (PS-1)).

[Synthesis Examples 46 and 47]
The same operation as in Synthesis Example 45 was carried out except that the type and amount of carboxylic acid used were changed as shown in Table 3, to obtain polyorganosiloxanes (polymers (PS-2) and (PS-3)).

<Preparation and Evaluation of Liquid Crystal Alignment Agent>
[Example 1: PSA type liquid crystal display element]
1. Preparation of liquid crystal alignment agent 5 parts by mass of compound (AD-5) and 3 parts by mass of compound (AD-8) were added to a solution containing 100 parts by mass of polymer (PI-6) obtained in Synthesis Example 6, and diluted with N-methyl-2-pyrrolidone (NMP) and butyl cellosolve (BC) to obtain a solution with a solvent composition of NMP/BC=50/50 (mass ratio) and a solid content concentration of 3.5% by mass. The liquid crystal alignment agent (AL-1) was prepared by filtering this solution through a filter with a pore size of 0.2 μm.

2. Preparation of Liquid Crystal Composition 5% by mass of a liquid crystal compound represented by the following formula (L1-1) and 0.3% by mass of a photopolymerizable compound represented by the following formula (L2-1) were added to 10 g of a nematic liquid crystal (MLC-6608, manufactured by Merck) and mixed to obtain a liquid crystal composition LC1.

3. Manufacturing of PSA type liquid crystal display element The liquid crystal alignment agent (AL-1) prepared 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 pre-baked for 1 minute on a hot plate at 80 ° C., and then heated for 1 hour at 200 ° C. in an oven substituted with nitrogen to remove the solvent, forming a coating film (liquid crystal alignment film) with a thickness of 0.08 μm. This coating film was subjected to rubbing treatment with a rubbing machine having a roll wrapped with rayon cloth at a roll rotation speed of 400 rpm, a stage movement speed of 3 cm / sec, and a pile push-in length of 0.1 mm. Thereafter, ultrasonic cleaning was performed in ultrapure water for 1 minute, and then drying was performed for 10 minutes in a 100 ° C. clean oven to obtain a substrate having a liquid crystal alignment film. This operation was repeated to obtain a pair (2 sheets) of substrates having a liquid crystal alignment film. Note that this rubbing treatment is a weak rubbing treatment performed for the purpose of controlling the collapse of the liquid crystal and performing alignment division in a simple manner.
An epoxy resin adhesive containing aluminum oxide spheres having a diameter of 3.5 μm was applied by screen printing to the outer periphery of the surface having the liquid crystal alignment film of one of the above substrates, and then the liquid crystal alignment film surfaces of the pair of substrates were placed opposite each other, overlapped and pressed together, and the adhesive was thermally cured by heating for 1 hour at 150° C. Next, the liquid crystal composition LC1 was filled into the gap between the substrates through the liquid crystal injection port, the liquid crystal injection port was sealed with an epoxy adhesive, and in order to eliminate flow alignment during liquid crystal injection, the resultant was heated at 150° C. for 10 minutes and then gradually cooled to room temperature.
Next, an AC voltage of 10 V with a frequency of 60 Hz was applied between the electrodes of the obtained liquid crystal cell, and while the liquid crystal was being driven, the cell was irradiated with ultraviolet light at an irradiation dose of 50,000 J/ ^m2 using an ultraviolet light irradiation device using a metal halide lamp as a light source. Note that this irradiation dose was measured using an actinometer measuring at a wavelength of 365 nm. In this manner, a PSA type liquid crystal cell was manufactured.

4. Evaluation (1) Measurement of voltage holding ratio A voltage of 1V was applied to the liquid crystal cell manufactured in 3. above for 60 microseconds, and then the voltage holding ratio (VHR) was measured 1670 milliseconds after the application was removed, and this was defined as the initial VHR. The measurement device used was a VHR measuring device "VHR-1" manufactured by Toyo Corporation. When the initial VHR was 90% or more, it was judged as "particularly good (◎)", when it was 85% or more and less than 90%, it was judged as "good (○)", when it was 75% or more and less than 85%, it was judged as "fair (△)", and when it was less than 75%, it was judged as "poor (×)". As a result, the initial VHR of this example was evaluated as "particularly good (◎)".

(2) Evaluation of reliability The reliability of the liquid crystal cell manufactured in 3. above was evaluated by voltage holding ratio. The evaluation was performed as follows. First, the initial VHR was measured in the same manner as in (1) above. Next, the liquid crystal cell was irradiated with CCFL (backlight) at 60° C. for one week, and then left to cool naturally to room temperature by standing at room temperature. After cooling, a voltage of 1 V was applied to the liquid crystal cell for 60 microseconds, and the voltage holding ratio (post-irradiation VHR) 1670 milliseconds after the application was removed was measured using a VHR measuring device "VHR-1" manufactured by Toyo Corporation. The rate of change in VHR (ΔVHR) at this time was calculated from the difference between the initial VHR and the post-irradiation VHR (ΔVHR=initial VHR-post-irradiation VHR), and the VHR reliability was evaluated based on ΔVHR. When ΔVHR was less than 3%, it was judged as "particularly good (◎)", when it was 3% or more and less than 10%, it was judged as "good (○)", when it was 10% or more and less than 15%, it was judged as "fair (△)", and when it was 15% or more, it was judged as "poor (×)". As a result, in this example, the VHR reliability was "particularly good (◎)".

(3) Evaluation of tilt imparting property A liquid crystal cell was produced in the same manner as in 3 above. In accordance with the method described in the non-patent document "T.J.Scheffer et. al. J. Appl. Phys. vo. 19, p. 2013 (1980)", the tilt angle of the liquid crystal molecules from the substrate surface was measured by a crystal rotation method using He-Ne laser light, and this was taken as the pretilt angle. When the measured value of the pretilt angle was less than 88.0°, it was judged as "particularly good (◎)", when it was 88.0° or more and less than 88.5°, it was judged as "good (○)", when it was 88.5° or more and less than 89.0°, it was judged as "fair (△)", and when it was 89.0° or more, it was judged as "poor (×)". As a result, the tilt imparting property of this example was "good (○)".

[Examples 2 to 17 and Comparative Examples 1 to 6]
For Examples 2, 3, 6, 8, 13, 14 and Comparative Examples 1 to 3, the liquid crystal alignment agent was prepared in the same manner as in Example 1 except that the types and amounts of the polymers and additives used in the preparation of the liquid crystal alignment agent were changed as shown in Table 4 (solvent composition: NMP/BC=50/50 (mass ratio)).
For Examples 4, 5, 7, 9 to 12, 15 to 17 and Comparative Examples 4 to 6, the types and amounts of the polymers and additives used in the preparation of the liquid crystal alignment agent were changed as shown in Table 4, and the composition of the solvent was changed to NMP/BC/N-ethyl-2-pyrrolidone (NEP)/diethylene glycol diethyl ether (DEDG)/diacetone alcohol (DAA) = 30/20/20/15/15 (mass ratio). Except for this, the liquid crystal alignment agent was prepared in the same manner as in Example 1.
In addition, a PSA type liquid crystal cell was produced using the obtained liquid crystal alignment agent in the same manner as in Example 1, and various evaluations were performed. The evaluation results are shown in Table 4. In Table 4, the numerical values in the polymer column and additive column indicate the blending ratio (parts by mass) of the solid content of each compound relative to 100 parts by mass of the total amount of the polymer components used in the preparation of the liquid crystal alignment agent (the same applies to Tables 5 to 7 below).

As shown in Table 4, Examples 1 to 17, which used a liquid crystal alignment agent containing compound [A], were evaluated as good in terms of initial VHR, reliability, and tilt-imparting ability. Of these, the liquid crystal alignment agents of Examples 2, 4 to 8, 10, and 13, which contained a polymer having a dihydrooxadiazole structure as compound [A], were particularly excellent in tilt-imparting ability. In contrast, Comparative Examples 1 to 3, 5, and 6, which used a liquid crystal alignment agent not containing compound [A], were inferior to Examples 1 to 17 in terms of initial VHR, reliability, and tilt-imparting ability, and Comparative Example 4 was inferior to Examples 1 to 17 in terms of initial VHR and reliability.

[Example 18: Optical VA type liquid crystal display element]
1. Preparation of liquid crystal alignment agent A solution containing 30 parts by weight of the polymer (PI-7) obtained in Synthesis Example 7 and a solution containing 70 parts by weight of the polymer (PI-26) obtained in Synthesis Example 26 were mixed, diluted with N-methyl-2-pyrrolidone (NMP), gamma butyrolactone (GBL), butyl cellosolve (BC) and diethylene glycol diethyl ether (DEDG), and further added with 5 parts by weight of compound (AD-2), to obtain a solution with a solvent composition of NMP/GBL/BC/DEDG=30/30/30/10 (mass ratio) and a solid content concentration of 3.5% by weight. The liquid crystal alignment agent (AL-24) was prepared by filtering this solution with a filter having a pore size of 0.2 μm.

2. Manufacturing of VA-type liquid crystal display element using photo-alignment method The liquid crystal alignment agent (AL-24) prepared above was applied to the transparent electrode surface of a glass substrate with a transparent electrode made of an ITO film by a spinner, and pre-baked on a hot plate at 80 ° C for 1 minute. After that, in an oven with nitrogen replacement, it was heated at 230 ° C for 1 hour to form a coating film with a thickness of 0.1 μm. Next, the surface of this coating film was irradiated with 1,000 J / m ² polarized ultraviolet light containing a 313 nm emission line using a Hg-Xe lamp and a Glan-Taylor prism from a direction inclined by 40 ° from the substrate normal to impart liquid crystal alignment ability. The same operation was repeated to prepare a pair (2 sheets) of substrates having a liquid crystal alignment film.
An epoxy resin adhesive containing aluminum oxide spheres with a diameter of 3.5 μm was applied by screen printing to the outer periphery of the surface having the liquid crystal alignment film of one of the above substrates, and then the liquid crystal alignment film surfaces of the pair of substrates were placed opposite each other and pressed together so that the projection directions of the optical axes of the ultraviolet rays of each substrate onto the substrate surface were antiparallel, and the adhesive was thermally cured at 150° C. for 1 hour. Next, a negative liquid crystal (MLC-6608, manufactured by Merck) was filled into the gap between the substrates through the liquid crystal injection port, and the liquid crystal injection port was then sealed with an epoxy adhesive. Furthermore, in order to remove flow alignment during liquid crystal injection, this was heated at 130° C. and then slowly cooled to room temperature.

3. Evaluation For the liquid crystal cells produced in 2 above, the initial VHR and reliability were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 5.

[Examples 19 to 23 and Comparative Examples 7 to 10]
A liquid crystal alignment agent was prepared in the same manner as in Example 18, except that the composition of the liquid crystal alignment agent was changed as shown in Table 5. In addition, a light-induced VA type liquid crystal cell was manufactured using the obtained liquid crystal alignment agent in the same manner as in Example 18, and various evaluations were performed. The results are shown in Table 5.

As shown in Table 5, Examples 18 to 23, which used a liquid crystal alignment agent containing compound [A], were evaluated as good in both initial VHR and reliability. In contrast, Comparative Examples 7 to 10, which used a liquid crystal alignment agent not containing compound [A], were evaluated as "△" or "×" in initial VHR and reliability, which were inferior to Examples 18 to 23.

[Example 24: Optical FFS type liquid crystal display element]
1. Preparation of liquid crystal alignment agent A solution containing 40 parts by mass of the polymer (PI-10) obtained in Synthesis Example 10 and a solution containing 60 parts by mass of the polymer (PI-31) obtained in Synthesis Example 31 were mixed and diluted with N-methyl-2-pyrrolidone (NMP), butyl cellosolve (BC), N-ethyl-2-pyrrolidone (NEP) and gamma butyrolactone (GBL) to obtain a solution with a solvent composition of NMP/BC/NEP/GBL=50/30/10/10 (mass ratio) and a solid content concentration of 3.5% by mass. The liquid crystal alignment agent (AL-34) was prepared by filtering this solution through a filter having a pore size of 0.2 μm.

2. Manufacturing of FFS-type liquid crystal display element using photo-alignment method A glass substrate (first substrate) on one side of which a flat electrode (bottom electrode), an insulating layer and a comb-shaped electrode (top electrode) were laminated in this order, and a glass substrate (second substrate) on which no electrode was provided was prepared. Next, a liquid crystal alignment agent (AL-34) was applied to each of the electrode-forming surface of the first substrate and one substrate surface of the second substrate by a spinner, and heated (pre-baked) on a hot plate at 80°C for 1 minute. Then, the substrate was dried (post-baked) for 30 minutes in an oven at 230°C with the interior replaced with nitrogen, to form a coating film with an average thickness of 0.1 μm. The obtained coating film was irradiated with 1,000 J/ ^m2 of linearly polarized ultraviolet light containing a 254 nm emission line from the substrate normal direction using a Hg-Xe lamp, to perform a photo-alignment treatment. The amount of irradiation was measured using an actinometer that measures at a wavelength of 254 nm. Next, the coating film that had been subjected to the photo-alignment treatment was heat-treated by heating in a clean oven at 230° C. for 30 minutes to form a liquid crystal alignment film.
Next, for one of the pair of substrates on which the liquid crystal alignment film was formed, an epoxy resin adhesive containing aluminum oxide spheres with a diameter of 3.5 μm was applied by screen printing to the outer edge of the surface having the liquid crystal alignment film. Thereafter, the substrates were overlapped and pressed together so that the projection directions of the polarization axis on the substrate surface during light irradiation were antiparallel, and the adhesive was thermally cured at 150° C. for 1 hour. Next, negative liquid crystal (MLC-6608, manufactured by Merck) was filled between the pair of substrates through the liquid crystal injection port, and the liquid crystal injection port was sealed with an epoxy adhesive to obtain a liquid crystal cell. Furthermore, in order to remove the flow alignment during liquid crystal injection, the substrate was heated at 120° C. and then slowly cooled to room temperature.

3. Evaluation For the liquid crystal cells produced in 2 above, the initial VHR and reliability were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 6.

[Examples 25 to 27 and Comparative Examples 11 to 13]
A liquid crystal alignment agent was prepared in the same manner as in Example 24, except that the composition of the liquid crystal alignment agent was changed as shown in Table 6. In addition, a photo-induced FFS type liquid crystal cell was manufactured using the obtained liquid crystal alignment agent in the same manner as in Example 24, and various evaluations were performed. The results are shown in Table 6.

As shown in Table 6, Examples 24 to 27, which used a liquid crystal alignment agent containing compound [A], were evaluated as good in both initial VHR and reliability. In contrast, Comparative Examples 11 to 13, which used a liquid crystal alignment agent not containing compound [A], were evaluated as "△" or "×" in initial VHR and reliability, which were inferior to Examples 24 to 27.

[Example 28: Rubbed FFS-type liquid crystal display element]
1. Preparation of liquid crystal alignment agent A solution containing 15 parts by mass of the polymer (PI-11) obtained in Synthesis Example 11 and a solution containing 85 parts by mass of the polymer (PI-23) obtained in Synthesis Example 23 were mixed and diluted with N-methyl-2-pyrrolidone (NMP), gamma butyrolactone (GBL), diacetone alcohol (DAA) and butyl cellosolve (BC) to obtain a solution with a solvent composition of NMP/GBL/DAA/BC = 30/30/30/10 (mass ratio) and a solid content concentration of 3.5% by mass. The liquid crystal alignment agent (AL-41) was prepared by filtering this solution through a filter with a pore size of 0.2 μm.

2. Manufacture of FFS-type liquid crystal display element using rubbing method A glass substrate (first substrate) having a flat electrode (bottom electrode), an insulating layer, and a comb-shaped electrode (top electrode) laminated in this order on one side, and a glass substrate (second substrate) without an electrode were prepared. Next, a liquid crystal alignment agent (AL-41) was applied to the electrode-formed surface of the first substrate and one side of the second substrate by a spinner, and heated (pre-baked) on a hot plate at 110°C for 3 minutes. Then, the substrate was dried (post-baked) for 30 minutes in an oven at 230°C with the interior replaced with nitrogen, to form a coating film with an average thickness of 0.08 μm. Next, the coating film surface was subjected to rubbing treatment with a rubbing machine having a roll wrapped with rayon cloth at a roll rotation speed of 1000 rpm, a stage movement speed of 3 cm/sec, and a pile indentation length of 0.3 mm. Then, ultrasonic cleaning was performed in ultrapure water for 1 minute, and then drying was performed in a clean oven at 100°C for 10 minutes to obtain a pair of substrates having a liquid crystal alignment film.
Next, a pair of substrates having a liquid crystal alignment film was screen-printed with an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 3.5 μm, leaving a liquid crystal injection port at the edge of the surface on which the liquid crystal alignment film was formed. The substrates were then superimposed and pressed together, and the adhesive was thermally cured at 150° C. for 1 hour. Next, a negative liquid crystal (MLC-6608, manufactured by Merck) was filled into the gap between the pair of substrates through the liquid crystal injection port, and the liquid crystal injection port was then sealed with an epoxy adhesive. Furthermore, in order to remove flow alignment during liquid crystal injection, the substrate was heated at 120° C. and then slowly cooled to room temperature to produce a liquid crystal cell. When the pair of substrates were superimposed, the rubbing method of each substrate was set to be antiparallel.

3. Evaluation The liquid crystal cells produced in 2. above were evaluated for initial VHR and reliability in the same manner as in Example 1. The evaluation results are shown in Table 7.

[Examples 29 to 31 and Comparative Examples 14 to 16]
A liquid crystal alignment agent was prepared in the same manner as in Example 28, except that the composition of the liquid crystal alignment agent was changed as shown in Table 7. In addition, using the obtained liquid crystal alignment agent, an FFS-type liquid crystal cell was manufactured by a rubbing method in the same manner as in Example 28, and various evaluations were performed. The results are shown in Table 7.

As shown in Table 7, Examples 28 to 31, which used a liquid crystal alignment agent containing compound [A], were evaluated as good in both initial VHR and reliability. In contrast, Comparative Examples 14 to 16, which used a liquid crystal alignment agent not containing compound [A], were evaluated as "△" or "×" in initial VHR and reliability, which were inferior to Examples 28 to 31.

The above results show that a liquid crystal alignment agent containing compound [A] having a heterocyclic structure (a) can provide a liquid crystal element with high voltage retention, excellent pretilt angle imparting properties, and excellent reliability with little change in pretilt angle even when driven for a long period of time.

Claims (18)

A liquid crystal aligning agent comprising a compound [A] having a heterocyclic structure (a) represented by the following formula (1-1), formula (1-2) or formula (1-3):

(In formulas (1-1) to (1-3), m1 and m2 each independently represent an integer from 1 to 3. ^Z1 represents a single bond or a carbonyl group. "*" represents a bond.) The liquid crystal aligning agent according to claim 1, wherein an aromatic hydrocarbon ring or an aromatic heterocycle is bonded to the heterocyclic structure (a). The liquid crystal alignment agent according to claim 1, wherein the compound [A] is a polymer having the heterocyclic structure (a). The liquid crystal alignment agent according to claim 3, wherein the polymer is at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane, and addition polymer. The liquid crystal alignment agent according to claim 3, wherein the polymer has the heterocyclic structure (a) in a side chain. The liquid crystal alignment agent according to claim 3, wherein the polymer has the heterocyclic structure (a) in the main chain. The liquid crystal alignment agent according to claim 3, wherein the polymer has a structural unit derived from a diamine compound having the heterocyclic structure (a). The liquid crystal aligning agent according to claim 3, wherein the polymer has at least one selected from the group consisting of a structural unit represented by the following formula (3-1) and a structural unit represented by the following formula (3-2):

In formula (3-1), R ²¹ is a hydrogen atom or a methyl group. X ¹ is —COO—, —CONH— or a divalent aromatic ring group. X ² is a single bond or a divalent organic group. ^{A 1} is a divalent group having the heterocyclic structure (a). Y ¹ is a hydrogen atom or a monovalent organic group.
In formula (3-2), R ²² and R ²³ are each independently a hydrogen atom or a methyl group. X ³ is a divalent organic group. A ² is a divalent group having the heterocyclic structure (a). Y ² is a hydrogen atom or a monovalent organic group. The liquid crystal alignment agent according to claim 1, wherein the compound [A] is a low molecular weight compound having a molecular weight of 1,000 or less. The liquid crystal aligning agent according to claim 9, wherein the compound [A] has a crosslinkable group. The liquid crystal alignment agent according to claim 1, further comprising a polymer that does not have the heterocyclic structure (a). The liquid crystal alignment agent according to claim 1, further comprising a crosslinkable compound that does not have the heterocyclic structure (a). A liquid crystal alignment film formed using the liquid crystal alignment agent according to any one of claims 1 to 12. A step of forming a coating film using the liquid crystal aligning agent according to any one of claims 1 to 12;
a step of irradiating the coating film with light to impart liquid crystal alignment ability;
A method for producing a liquid crystal alignment film comprising the steps of: A step of forming a coating film using the liquid crystal aligning agent according to any one of claims 1 to 12 on each of the conductive films of a pair of substrates having a conductive film;
a step of constructing a liquid crystal cell by disposing a pair of substrates on which the coating film is formed such that the coating film faces each other via a liquid crystal layer containing a photopolymerizable compound;
applying a voltage between the conductive films to the liquid crystal cell;
A method for manufacturing a liquid crystal element comprising the steps of: A liquid crystal element comprising the liquid crystal alignment film according to claim 13. A polymer having a heterocyclic structure (a) represented by the following formula (1-1), formula (1-2) or formula (1-3):

(In formulas (1-1) to (1-3), m1 and m2 each independently represent an integer from 1 to 3. ^Z1 represents a single bond or a carbonyl group. "*" represents a bond.) Diamines represented by the following formula (2-1), formula (2-2) or formula (2-3).

In formula (2-1), Ar ¹ is a (p+2)-valent aromatic ring group. p is an integer from 1 to 4. r is 1 or 2. ^{X 11} is a single bond, -O-, -S-, -CO-, -COO-, -NR ³ -, -CO-NR ³ -, -CH ₂ -O-, -CH ₂ -CO- or -CH ₂ -OCO- when r is 1, and is a nitrogen atom or *-CO-N(-*) ₂ when r is 2. "*" represents a bond. R ¹ is a single bond, a divalent hydrocarbon group having 1 to 20 carbon atoms, a divalent group R ^k1 having 2 to 20 carbon atoms containing -O-, -S-, -CO-, -COO-, -NR ³ - or -CONR ³ - between the carbon-carbon bonds of the hydrocarbon group, or a divalent hydrocarbon group or a divalent group R is a group in which at least a part of the hydrogen atoms in ^k1 is replaced with a substituent. R ³ is a hydrogen atom or a monovalent organic group. ^{Y 11} is a divalent group having a heterocyclic structure (a) represented by the following formula (1-1), formula (1-2) or formula (1-3). R ² is a hydrogen atom or a monovalent organic group. When a plurality of X ¹¹ , R ¹ , Y ¹¹ , R ² and r are present in the formula, the plurality of X ¹¹ , R ¹ , Y ¹¹ , R ² and r are the same or different from each other.

(In formula (2-2), Ar ² and Ar ³ are each independently a divalent aromatic ring group. R ⁴ and R ⁵ are each independently a single bond or a divalent organic group. Y ¹² is a divalent group having a heterocyclic structure (a) represented by formula (1-1), formula (1-2) or formula (1-3) below. k is an integer of 0 to 3. When a plurality of Y ^{12 s} and R ^{5 s} are present in the formula, the plurality of Y ^{12 s} and R ^{5 s} are the same or different.)

(In formula (2-3), Ar ⁴ and Ar ⁵ are each independently a divalent aromatic ring group. R ⁶ is a trivalent organic group. X ¹² is a single bond, -O-, -S-, -CO-, -COO-, -NR ⁹ -, -CO-NR ⁹ -, -CH ₂ -O-, -CH ₂ -CO-, or -CH ₂ -OCO-. R ⁷ is a single bond, a divalent hydrocarbon group having 1 to 20 carbon atoms, a divalent group R k2 having 2 to 20 carbon atoms containing -O-, -S-, -CO-, -COO-, -NR ⁹ -, or -CO-NR ⁹ - between the carbon-carbon bonds of the hydrocarbon ^group , or a group in which at least a portion of the hydrogen atoms in the divalent hydrocarbon group or the divalent group R ^k2 are replaced with a substituent. R ⁹ is a hydrogen atom or a monovalent organic group. Y ^{R 13} is a divalent group having a heterocyclic structure (a) represented by the following formula (1-1), formula (1-2) or formula (1-3). R ⁸ is a hydrogen atom or a monovalent organic group.

(In formulas (1-1) to (1-3), m1 and m2 each independently represent an integer from 1 to 3. ^Z1 represents a single bond or a carbonyl group. "*" represents a bond.)