JP2024059149A - Liquid crystal alignment agent, liquid crystal alignment film, liquid crystal element, and method for producing liquid crystal alignment film - Google Patents

Abstract

[Problem] To provide a liquid crystal alignment film having good contrast and afterimage characteristics and maintaining a high voltage holding ratio. [Solution] A liquid crystal alignment agent in which at least one polymer is a polymer obtained by reacting a tetracarboxylic acid derivative with a diamine, and the tetracarboxylic acid derivative contains at least one selected from the group consisting of a compound represented by formula (1) and a compound derived therefrom. TIFF2024059149000160.tif51138In formula (1), R each independently represents an alkyl group having 1 to 6 carbon atoms, and n each independently represents an integer of 1 to 4. [Selected Figure] None

Description

The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal element using the same. More specifically, the present invention relates to a liquid crystal alignment agent for forming a liquid crystal alignment film using a photo-alignment method (hereinafter, sometimes abbreviated as a photo-alignment film), a liquid crystal alignment film using a photo-alignment method formed using the liquid crystal alignment agent, and a liquid crystal display element having the liquid crystal alignment film (hereinafter, sometimes abbreviated as a liquid crystal element).

Liquid crystal elements are known that can cause optical phenomena such as refraction, scattering, and reflection of electromagnetic waves incident on the element by controlling or modulating the orientation state of the liquid crystal layer within the element. In addition to the liquid crystal display elements listed below, liquid crystal antennas, dimming windows, optical compensation materials, and variable phase shifters are also known.

Liquid crystal display elements are known to have various driving methods, such as TN (Twisted Nematic) mode, STN (Super Twisted Nematic) mode, IPS (In-Plane Switching) mode, FFS (Fringe Field Switching) mode, and vertical alignment VA (Multi-domain Vertical Alignment) mode. These liquid crystal display elements are used in image display devices for various electronic devices such as televisions and mobile phones, and development is underway to further improve display quality. Specifically, the performance of liquid crystal display elements is improved not only by improvements in the driving method and element structure, but also by the components used in the elements. Among the components used in liquid crystal display elements, the liquid crystal alignment film in particular is one of the important materials related to display quality, and research into this liquid crystal alignment film is being actively conducted in order to meet the demand for higher quality liquid crystal display elements.

Here, the liquid crystal alignment film is provided on a pair of substrates provided on both sides of the liquid crystal layer of the liquid crystal display element, in contact with the liquid crystal layer, and has the function of orienting the liquid crystal molecules that make up the liquid crystal layer with a certain regularity relative to the substrates. By using a liquid crystal alignment film with high liquid crystal alignment properties, it is possible to realize a liquid crystal display element with high contrast and improved afterimage characteristics (see, for example, Patent Documents 1 and 2).

Currently, such liquid crystal alignment films are mainly formed using solutions (varnishes) in which polyamic acid, soluble polyimide, or polyamic acid ester is dissolved in an organic solvent. To form a liquid crystal alignment film using these varnishes, the varnish is applied to a substrate, and the coating is solidified by heating or other means to form a polyimide-based liquid crystal alignment film, which is then subjected to an alignment treatment suitable for the display mode described above as necessary. Known alignment treatment methods include the rubbing method, in which the surface of the alignment film is rubbed with a cloth or the like to align the direction of the polymer molecules, and the photoalignment method, in which the alignment film is irradiated with linearly polarized ultraviolet light to cause photochemical changes such as photoisomerization and dimerization in the polymer molecules to impart anisotropy to the film. Of these, the photoalignment method has the advantages of being more uniform in alignment than the rubbing method, being a non-contact alignment treatment method that does not scratch the film, and reducing the causes of display defects in liquid crystal display elements such as dust generation and static electricity.

For example, Patent Documents 1 to 6 describe liquid crystal alignment films produced using such photoalignment methods, in which diaminoazobenzene and the like are used as raw materials and photoisomerization technology is applied to obtain photoalignment films with large anchoring energy and good liquid crystal alignment properties.

JP 2010-197999 A International Publication No. 2013/157463 JP 2005-275364 A JP 2007-248637 A JP 2009-069493 A International Publication No. 2015/016118

In recent years, there has been an increasing demand for high-quality liquid crystal display elements, with demands for reliability that allows contrast, image retention, and a high voltage holding ratio (VHR) to be maintained for a long period of time. Maintaining a high voltage holding ratio is important to prevent a decline in display quality. On the other hand, in consideration of outdoor use, there is also a demand for the brightness of the backlight, which serves as the light source, to be higher than previous versions. In situations where the display is exposed to such high-brightness backlights, it is important to increase the VHR reliability against light, which is a particularly important issue for photo-alignment films, which generally have inferior electrical properties compared to rubbed alignment films.

The inventors therefore conducted extensive research with the objectives of providing a liquid crystal alignment film capable of forming a liquid crystal display element that has good contrast and afterimage characteristics, maintains a high voltage retention rate even when exposed to strong light for a long period of time, and does not degrade in display quality, and of providing a liquid crystal alignment agent capable of forming such a liquid crystal alignment film.

As a result of intensive research to solve the above problems, the present inventors have found that by using a tetracarboxylic acid derivative represented by formula (1), a liquid crystal alignment film with high liquid crystal alignment properties can be obtained, and that by using this liquid crystal alignment film, a liquid crystal display element can be formed which has good contrast and afterimage characteristics, and which maintains a high voltage retention rate and does not deteriorate in display quality even when exposed to strong light for a long period of time, and have completed the present invention.
The present invention includes the following configurations.

式（１）中、Ｒは互いに独立して炭素数１～６のアルキルを示し、ｎは互いに独立して１～４の整数を表す。
［２］ 前記テトラカルボン酸誘導体とジアミン類を反応させてなるポリマーの原料として使用される原料組成物に、式（１）で表される化合物およびその誘導化合物からなる群から選択された少なくとも１つと、光反応により配向膜に液晶配向性を付与する光反応性構造を有する化合物を含む［１］に記載の液晶配向剤。
［３］ 前記光反応が、光異性化、光フリース転位、光分解、および光二量化のうち少なくとも１つである［２］に記載の液晶配向剤。
［４］ 前記光反応性構造を有する化合物が、式（２）で表される化合物の少なくとも１つである、［２］に記載の液晶配向剤。

式（２）においてＸは炭素数１～１２のアルキレンであり、前記アルキレンの－（ＣＨ_２）_２－の隣り合わない１つ以上が－Ｏ－または－ＮＨ－で置き換えられていてもよく、
Ｒ^ａおよびＲ^ｂはそれぞれ独立して水素、－ＣＨ_３、－ＯＣＨ_３、－ＣＦ_３、－Ｆ、－ＣＯＯＣＨ_３、または式（Ｐ１－１）もしくは式（Ｐ１－２）で表される１価の基であり、
Ｒ^ｃはそれぞれ独立して水素、－ＣＨ_３、－ＯＣＨ_３、－ＣＦ_３、－Ｆ、または式（Ｐ１－１）もしくは式（Ｐ１－２）で表される１価の基であり、ｊは０または１であり、ａ～ｃはそれぞれ独立に０～２の整数であり、

式（Ｐ１－１）および式（Ｐ１－２）において、Ｒ^６ａ、Ｒ^７ａおよびＲ^８ａは、それぞれ独立して、
水素、置換もしくは無置換のアルキル、置換もしくは無置換のアルカノイル、
置換もしくは無置換のアルコキシカルボニル、または置換もしくは無置換のアリールカルボニルを表し、Ｒ^６ａ、Ｒ^７ａおよびＲ^８ａは互いに同一であっても異なっていてもよく、＊は、式（２）におけるベンゼン環への結合位置を表し、
式（２）において、環を構成するいずれかの炭素に結合位置が固定されていない基は、その環における結合位置が任意であることを示す。
［５］ 前記式（２）で表される化合物が、式（２－１）～式（２－３）のいずれか１つである、［４］に記載の液晶配向剤。

式（２－１）において、Ｒ^１ａおよびＲ^１ｃは、それぞれ独立して、水素または式（Ｐ１－１）もしくは式（Ｐ１－２）で表される１価の基を表し、
式（２－２）において、Ｒ^２ａおよびＲ^２ｂは、それぞれ独立して、水素または式（Ｐ１－１）もしくは式（Ｐ１－２）で表される１価の基を表し、Ｒ^２ｃはそれぞれ独立して水素、－ＣＨ_３、－ＯＣＨ_３、－ＣＦ_３、または－Ｆであり、
Ｘ_１は炭素数１～１２のアルキレンであり、前記アルキレンの－（ＣＨ_２）_２－の隣り合わない１つ以上が－Ｏ－または－ＮＨ－で置き換えられていてもよく、ｋは０～２の整数であり、
式（２－３）において、Ｒ^３ａは、それぞれ独立して、水素または式（Ｐ１－１）もしくは式（Ｐ１－２）で表される１価の基を表し、Ｒ^４およびＲ^５は、それぞれ独立して、水素または－Ｆであり、Ｒ^４およびＲ^５が同時に水素となることはなく、Ｒ^3ｃはそれぞれ独立して水素、－ＣＨ_３、－ＯＣＨ_３、－ＣＦ_３、または－Ｆであり、Ｘ_１は炭素数１～１２のアルキレンであり、前記アルキレンの－（ＣＨ_２）_２－の隣り合わない１つ以上が－Ｏ－または－ＮＨ－で置き換えられていてもよく、ｍは０～２の整数であり、

式（Ｐ１－１）および式（Ｐ１－２）において、Ｒ^６ａ、Ｒ^７ａおよびＲ^８ａは、それぞれ独立して、水素、置換もしくは無置換のアルキル、置換もしくは無置換のアルカノイル、置換もしくは無置換のアルコキシカルボニル、または置換もしくは無置換のアリールカルボニルを表し、Ｒ^６ａ、Ｒ^７ａおよびＲ^８ａは互いに同一であっても異なっていてもよく、＊は、式（２－１）、式（２－２）または式（２－３）におけるベンゼン環への結合位置を表し、
式（２－１）、式（２－２）または式（２－３）において、環を構成するいずれかの炭素に結合位置が固定されていない基は、その環における結合位置が任意であることを示す。
［６］ 前記光反応性構造を有する化合物が、式（３）で表される化合物の少なくとも１つである、［２］に記載の液晶配向剤。

式（３）において、Ｒ^１及びＲ^２はそれぞれ独立して水子、ハロゲン、炭素数１から６のアルキル、炭素数１～６のハロアルキルまたは炭素数１～６のアルコキシを表し、Ｒ^１とＲ^２は一体となって置換されていてもよいメチレンを形成してもよく、Ｘはそれぞれ独立してハロゲン、炭素数１～６のアルキル、炭素数１～６のハロアルキルまたは炭素数１～６のアルコキシを表し、ｎは独立して０～４の整数を表す。
［７］ 前記式（１）で表される化合物が、式（１－１－１）で表される［１］～［６］のいずれか１項に記載の液晶配向剤。

［８］ ［１］～［７］のいずれか１項に記載の液晶配向剤から形成される液晶配向膜。
［９］ ［８］に記載の液晶配向膜を有する液晶素子。
［１０］ ［２］～［７］のいずれか１項に記載の液晶配向剤を基板に塗布する工程と、その塗膜に偏光紫外線を照射する工程とを含む、液晶配向膜の製造方法。 [1] A liquid crystal aligning agent comprising at least one polymer and a solvent, the at least one polymer being a polymer obtained by reacting a tetracarboxylic acid derivative with a diamine, the tetracarboxylic acid derivative comprising at least one selected from the group consisting of a compound represented by formula (1) and a compound derived therefrom.

In formula (1), R's each independently represent an alkyl group having 1 to 6 carbon atoms, and n's each independently represent an integer of 1 to 4.
[2] The liquid crystal alignment agent according to [1], wherein the raw material composition used as a raw material for the polymer obtained by reacting the tetracarboxylic acid derivative with a diamine contains at least one selected from the group consisting of the compound represented by formula (1) and its derivative compound, and a compound having a photoreactive structure that imparts liquid crystal alignment to the alignment film by photoreaction.
[3] The liquid crystal aligning agent according to [2], wherein the photoreaction is at least one of photoisomerization, photo-Fries rearrangement, photodecomposition, and photodimerization.
[4] The liquid crystal aligning agent according to [2], wherein the compound having a photoreactive structure is at least one compound represented by formula (2):

In formula (2), X is an alkylene having 1 to 12 carbon atoms, and one or more non-adjacent —(CH ₂ ) ₂ — groups in the alkylene may be replaced with —O— or —NH—;
R ^a and R ^b each independently represent a hydrogen atom, —CH ₃ , —OCH ₃ , —CF ₃ , —F, —COOCH ₃ , or a monovalent group represented by formula (P1-1) or formula (P1-2);
R ^c each independently represents hydrogen, —CH ₃ , —OCH ₃ , —CF ₃ , —F, or a monovalent group represented by formula (P1-1) or formula (P1-2); j is 0 or 1; a to c each independently represent an integer of 0 to 2;

In formula (P1-1) and formula (P1-2), R ^6a , R ^7a and R ^8a each independently represent
Hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkanoyl,
R ^6a , R ^7a and R ^8a may be the same or different, * represents the bonding position to the benzene ring in formula (2),
In formula (2), a group that is not bonded to any carbon atom constituting a ring indicates that the bond may be made to any position on the ring.
[5] The liquid crystal aligning agent according to [4], wherein the compound represented by formula (2) is any one of formulas (2-1) to (2-3).

In formula (2-1), R ^1a and R ^1c each independently represent a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2).
In formula (2-2), R ^2a and R ^2b each independently represent a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2); R ^2c each independently represent a hydrogen atom, -CH ₃ , -OCH ₃ , -CF ₃ , or -F;
X ₁ is an alkylene having 1 to 12 carbon atoms, in which one or more non-adjacent —(CH ₂ ) ₂ — groups in the alkylene may be replaced with —O— or —NH—, and k is an integer of 0 to 2;
In formula (2-3), R ^3a each independently represents hydrogen or a monovalent group represented by formula (P1-1) or formula (P1-2); R ⁴ and R ⁵ each independently represent hydrogen or -F, and R ⁴ and R ⁵ are not simultaneously hydrogen; R ^3c each independently represents hydrogen, -CH ₃ , -OCH ₃ , -CF ₃ , or -F; X ₁ represents an alkylene having 1 to 12 carbon atoms, and one or more non-adjacent -(CH ₂ ) ₂ - of the alkylene may be replaced by -O- or -NH-; m represents an integer of 0 to 2;

In formula (P1-1) and formula (P1-2), R ^6a , R ^7a and R ^8a each independently represent hydrogen, a substituted or unsubstituted alkyl, a substituted or unsubstituted alkanoyl, a substituted or unsubstituted alkoxycarbonyl, or a substituted or unsubstituted arylcarbonyl, R ^6a , R ^7a and R ^8a may be the same or different, * represents a bonding position to a benzene ring in formula (2-1), formula (2-2) or formula (2-3),
In the formula (2-1), (2-2) or (2-3), a group that is not bonded to any carbon atom constituting a ring means that the bond position in the ring is optional.
[6] The liquid crystal aligning agent according to [2], wherein the compound having a photoreactive structure is at least one compound represented by formula (3):

In formula (3), ^R1 and ^R2 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms; ^R1 and ^R2 may be joined together to form an optionally substituted methylene; each X each independently represent a halogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms; and n each independently represent an integer of 0 to 4.
[7] The liquid crystal aligning agent according to any one of items [1] to [6], wherein the compound represented by formula (1) is represented by formula (1-1-1):

[8] A liquid crystal alignment film formed from the liquid crystal aligning agent according to any one of [1] to [7].
[9] A liquid crystal element having the liquid crystal alignment film according to [8].
[10] A method for producing a liquid crystal alignment film, comprising the steps of applying the liquid crystal aligning agent according to any one of [2] to [7] to a substrate and irradiating the coating with polarized ultraviolet light.

By using the liquid crystal alignment agent of the present invention, a liquid crystal alignment film with high liquid crystal alignment properties can be obtained. In addition, by using this liquid crystal alignment film, it is possible to realize a liquid crystal display element that has excellent afterimage characteristics and contrast, and maintains a high voltage retention rate and does not deteriorate in display quality even when exposed to strong light for a long period of time.

The present invention will be described in detail below. The following description of the constituent elements may be based on a representative embodiment or specific example, but the present invention is not limited to such an embodiment. As one embodiment of the present invention, the liquid crystal alignment agent of the present invention can be used as a liquid crystal alignment agent for photo-alignment by using a compound having a photoreactive structure. The liquid crystal alignment agent for photo-alignment is a liquid crystal alignment agent that can be given anisotropy by forming a film of the liquid crystal alignment agent on a substrate and irradiating it with polarized ultraviolet light, and is sometimes simply referred to as a "liquid crystal alignment agent" in this specification. In addition, an alignment film formed from a liquid crystal alignment agent for photo-alignment may be referred to as a photo-alignment film or simply as an alignment film. In addition, in the present invention, a "tetracarboxylic acid derivative" refers to a tetracarboxylic acid dianhydride, a tetracarboxylic acid diester, or a tetracarboxylic acid diester dihalide. In addition, in the present invention, diamines and dihydrazides may be referred to as "diamines".

<Liquid crystal aligning agent of the present invention>
The liquid crystal aligning agent of the present invention is characterized in that it contains at least one polymer selected from the group consisting of polyamic acid and polyamic acid derivatives obtained by reacting a tetracarboxylic acid derivative with a diamine, and contains at least one compound represented by formula (1) as a raw material of the polymer. In the present invention, the polyamic acid derivative refers to polyimide, partial polyimide, polyamic acid ester, polyamic acid-polyamide copolymer, and polyamideimide. Such a polymer may be referred to as the polymer of the present invention.

式（１）中、Ｒは互いに独立して炭素数１～６のアルキルを示し、ｎは互いに独立して１～４の整数を表す。 <Compound represented by formula (1) and its derivative compound>
The compound represented by formula (1) used in the polymer contained in the liquid crystal aligning agent of the present invention will be described.

In formula (1), R's each independently represent an alkyl group having 1 to 6 carbon atoms, and n's each independently represent an integer of 1 to 4.

The derivative compound of the compound represented by formula (1) is, for example, a tetracarboxylic acid diester or a tetracarboxylic acid diester dihalide derived from a tetracarboxylic acid dianhydride. In the present invention, the "compound represented by formula (1) and its derivative compound" may be collectively referred to as the "tetracarboxylic acid derivative represented by formula (1)."

By using the tetracarboxylic acid derivative represented by formula (1) as a polymer raw material, it is possible to form a liquid crystal display element that has good contrast and afterimage characteristics, and maintains a high voltage retention rate and does not deteriorate in display quality even when exposed to strong light for a long period of time. The reason for this is not entirely clear, but it is thought to be as follows.

The tetracarboxylic acid derivative represented by formula (1) has a biphenyl structure in the central skeleton. Due to this biphenyl structure, a liquid crystal alignment film using the tetracarboxylic acid derivative represented by formula (1) as a raw material has strong interaction with liquid crystal molecules and can exhibit high liquid crystal alignment properties. As a result, it is believed that when a liquid crystal alignment film is formed using a liquid crystal alignment agent containing a polymer using the tetracarboxylic acid derivative represented by formula (1) as a raw material and a liquid crystal display element is formed using this film, excellent image retention characteristics and contrast will be exhibited.

On the other hand, some of the hydrogen atoms in this biphenyl structure are replaced by R. The presence of this R causes a twist between the two benzene rings in the biphenyl structure, and the π conjugation of the biphenyl structure is interrupted. As a result, the polyimide alignment film using the tetracarboxylic acid derivative represented by formula (1) as a raw material has suppressed electronic conjugation of the polymer chain and has a smaller absorption coefficient in the wavelength region of light irradiated from the backlight than when a general aromatic tetracarboxylic acid dianhydride is used. Therefore, if a liquid crystal alignment film is formed using a liquid crystal alignment agent containing a polymer using the tetracarboxylic acid derivative represented by formula (1) as a raw material and a liquid crystal display element is formed using this film, it is believed that the decrease in VHR of the liquid crystal display element caused by light irradiation can be suppressed.

式（１－１）～（１－４）中、Ｒは互いに独立して炭素数１～６のアルキルを示す。 Specific examples of the compound represented by formula (1) include the following compounds.

In formulas (1-1) to (1-4), R's each independently represent an alkyl group having 1 to 6 carbon atoms.

A preferred specific example of the compounds represented by formulas (1-1) to (1-4) is the compound represented by formula (1-1-1).

The total content of the compounds represented by formula (1) in the polymer of the present invention is preferably 10 mol % to 50 mol % based on the total amount of the tetracarboxylic acid derivatives in the monomer.

<Compound having a photoreactive structure>
When the liquid crystal alignment agent of the present invention is used as a liquid crystal alignment agent for photo-alignment, it is preferable to use it in combination with a compound having a photoreactive structure. In this specification, the photoreactive structure refers to a structure that undergoes a photoreaction by irradiation with light containing a specific wavelength band corresponding to the photoreactive structure. Examples of photoreactions include photoisomerization, photo-fries rearrangement, photodecomposition, and photodimerization. By using a compound having a photoreactive structure as a raw material, the photoreactive structure can be incorporated into a polymer. In addition, the compounds listed in this specification as having a photoreactive structure can also be used as raw materials as compounds without a photoreactive structure when light containing a specific wavelength band corresponding to the photoreactive structure is not irradiated in the process of forming an alignment film from the liquid crystal alignment agent.

When a liquid crystal alignment film using a compound having a photoreactive structure, as exemplified below, is formed by irradiating a coating of a liquid crystal alignment agent for photo-alignment with polarized light of a specified wavelength, the photoreactive structure of the polymer main chain, which is roughly parallel to the direction of polarization, undergoes a photoreaction, and the components of the polymer chain that are oriented in a specific direction (roughly perpendicular to the polarization direction of the irradiated light) become dominant, imparting anisotropy to the coating. This state in which the components of the polymer chain that are oriented in a specific direction become dominant is expressed as the polymer chain being oriented. When the photoalignment film formed by baking this coating is used in a liquid crystal display element, the interaction between the surface of the oriented film and the liquid crystal molecules results in the liquid crystal molecules being oriented with their long axes aligned in a certain direction (roughly perpendicular to the polarization direction of the irradiated light).

式（Ａ）において、＊は結合手であり、結合手のベンゼン環に対する結合位置はそれぞれ独立して任意であり、ベンゼン環の置換可能な水素は置換基で置き換えられていてもよい。 <Structure that causes photoisomerization reaction>
In the present invention, an example of a structure that causes a photoisomerization reaction is a structure having an azobenzene skeleton. In this specification, the structure having an azobenzene skeleton means a structure represented by the following formula (A).

In formula (A), * represents a bond, and the bonding positions of the bonds to the benzene ring are each independently arbitrary, and any substitutable hydrogen atom on the benzene ring may be replaced by a substituent.

式（２）においてＸは炭素数１～１２のアルキレンであり、前記アルキレンの－（ＣＨ_２）_２－の隣り合わない１つ以上が－Ｏ－または－ＮＨ－で置き換えられていてもよく、
Ｒ^ａおよびＲ^ｂはそれぞれ独立して水素、－ＣＨ_３、－ＯＣＨ_３、－ＣＦ_３、－Ｆ、－ＣＯＯＣＨ_３、または式（Ｐ１－１）もしくは式（Ｐ１－２）で表される１価の基であり、Ｒ^ｃはそれぞれ独立して水素、－ＣＨ_３、－ＯＣＨ_３、－ＣＦ_３、－Ｆ、または式（Ｐ１－１）もしくは式（Ｐ１－２）で表される１価の基であり、ｊは０または１であり、ａ～ｃはそれぞれ独立に０～２の整数であり、

式（Ｐ１－１）および式（Ｐ１－２）において、Ｒ^６ａ、Ｒ^７ａおよびＲ^８ａは、それぞれ独立して、水素、置換もしくは無置換のアルキル、置換もしくは無置換のアルカノイル、置換もしくは無置換のアルコキシカルボニル、または置換もしくは無置換のアリールカルボニルを表し、Ｒ^６ａ、Ｒ^７ａおよびＲ^８ａは互いに同一であっても異なっていてもよく、＊は、式（２）におけるベンゼン環への結合位置を表し、
式（２）において、環を構成するいずれかの炭素に結合位置が固定されていない基は、その環における結合位置が任意であることを示す。 The compound having an azobenzene structure used in the polymer contained in the liquid crystal aligning agent of the present invention is specifically a compound represented by formula (2).

In formula (2), X is an alkylene having 1 to 12 carbon atoms, and one or more non-adjacent —(CH ₂ ) ₂ — groups in the alkylene may be replaced with —O— or —NH—;
R ^a and R ^b are each independently hydrogen, -CH ₃ , -OCH ₃ , -CF ₃ , -F, -COOCH ₃ , or a monovalent group represented by formula (P1-1) or formula (P1-2); R ^c are each independently hydrogen, -CH ₃ , -OCH ₃ , -CF ₃ , -F, or a monovalent group represented by formula (P1-1) or formula (P1-2); j is 0 or 1; and a to c are each independently an integer of 0 to 2;

In formula (P1-1) and formula (P1-2), R ^6a , R ^7a , and R ^8a each independently represent hydrogen, a substituted or unsubstituted alkyl, a substituted or unsubstituted alkanoyl, a substituted or unsubstituted alkoxycarbonyl, or a substituted or unsubstituted arylcarbonyl, R ^6a , R ^7a , and R ^8a may be the same or different, * represents the bonding position to the benzene ring in formula (2),
In formula (2), a group that is not bonded to any carbon atom constituting a ring indicates that the bond may be made to any position on the ring.

式（２－１）において、Ｒ^１ａおよびＲ^１ｃは、それぞれ独立して、水素、式（Ｐ１－１）または式（Ｐ１－２）で表される１価の基を表し、
式（２－２）において、Ｒ^２ａおよびＲ^２ｂは、それぞれ独立して、水素、式（Ｐ１－１）または式（Ｐ１－２）で表される１価の基を表し、Ｒ^２ｃはそれぞれ独立して水素、－ＣＨ_３、－ＯＣＨ_３、－ＣＦ_３、または－Ｆであり、Ｘ_１は炭素数１～１２のアルキレンであり、前記アルキレンの－（ＣＨ_２）_２－の隣り合わない１つ以上が－Ｏ－または－ＮＨ－で置き換えられていてもよく、ｋは０～２の整数であり、
式（２－３）において、Ｒ^３ａは、それぞれ独立して、水素、式（Ｐ１－１）または式（Ｐ１－２）で表される１価の基を表し、Ｒ^４、Ｒ^５は、それぞれ独立して、水素または－Ｆであり、Ｒ^４およびＲ^５が同時に水素となることはなく、Ｒ^3ｃはそれぞれ独立して水素、－ＣＨ_３、－ＯＣＨ_３、－ＣＦ_３、または－Ｆであり、Ｘ_１は炭素数１～１２のアルキレンであり、前記アルキレンの－（ＣＨ_２）_２－の隣り合わない１つ以上が－Ｏ－または－ＮＨ－で置き換えられていてもよく、ｍは０～２の整数であり、

式（Ｐ１－１）および式（Ｐ１－２）において、Ｒ^６ａ、Ｒ^７ａおよびＲ^８ａは、それぞれ独立して、水素、置換もしくは無置換のアルキル、置換もしくは無置換のアルカノイル、置換もしくは無置換のアルコキシカルボニル、または置換もしくは無置換のアリールカルボニルを表し、Ｒ^６ａ、Ｒ^７ａおよびＲ^８ａは互いに同一であっても異なっていてもよく、＊は、式（２－１）、式（２－２）および式（２－３）におけるベンゼン環への結合位置を表し、
式（２－１）、式（２－２）および式（２－３）において、環を構成するいずれかの炭素に結合位置が固定されていない基は、その環における結合位置が任意であることを示す。 The compound represented by formula (2) is specifically a compound represented by the following formulas (2-1) to (2-3).

In formula (2-1), R ^1a and R ^1c each independently represent a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2).
In formula (2-2), R ^2a and R ^2b each independently represent hydrogen or a monovalent group represented by formula (P1-1) or formula (P1-2); R ^2c each independently represent hydrogen, -CH ₃ , -OCH ₃ , -CF ₃ , or -F; X ₁ represents an alkylene having 1 to 12 carbon atoms, and one or more non-adjacent -(CH ₂ ) ₂ - of the alkylene may be replaced by -O- or -NH-; k represents an integer of 0 to 2;
In formula (2-3), R ^3a each independently represents hydrogen or a monovalent group represented by formula (P1-1) or formula (P1-2); R ⁴ and R ⁵ each independently represent hydrogen or -F, and R ⁴ and R ⁵ are not simultaneously hydrogen; R ^3c each independently represents hydrogen, -CH ₃ , -OCH ₃ , -CF ₃ , or -F; X ₁ represents an alkylene having 1 to 12 carbon atoms, and one or more non-adjacent -(CH ₂ ) ₂ - of the alkylene may be replaced by -O- or -NH-; m represents an integer of 0 to 2;

In formula (P1-1) and formula (P1-2), R ^6a , R ^7a and R ^8a each independently represent hydrogen, a substituted or unsubstituted alkyl, a substituted or unsubstituted alkanoyl, a substituted or unsubstituted alkoxycarbonyl, or a substituted or unsubstituted arylcarbonyl, R ^6a , R ^7a and R ^8a may be the same or different, * represents a bonding position to a benzene ring in formula (2-1), formula (2-2) or formula (2-3),
In the formulae (2-1), (2-2) and (2-3), a group that is not bonded to any carbon atom constituting a ring means that the bonding position in the ring is arbitrary.

式（２－１－２）において、Ｒ^６ａは炭素数１～４のアルキルである。 Specific examples of the compound represented by formula (2-1) include the following compounds.

In formula (2-1-2), R ^6a is alkyl having 1 to 4 carbon atoms.

式（２－２－１）～式（２－２－６）において、Ｒ^６ａは炭素数１～４のアルキルであり、ｌは１～１０の整数であり、ｍは１～１１の整数である。 Specific examples of the compound represented by formula (2-2) include the following compounds.

In formulae (2-2-1) to (2-2-6), R ^6a is an alkyl group having 1 to 4 carbon atoms, l is an integer of 1 to 10, and m is an integer of 1 to 11.

式（２－３－１）および式（２－３－２）において、ｌは１～１０の整数である。 Specific examples of the compound represented by formula (2-3) include the following compounds.

In formulas (2-3-1) and (2-3-2), l is an integer of 1 to 10.

When the transparency of the formed liquid crystal alignment film is important, it is preferable to use one or more compounds selected from the group consisting of formula (2-1-2), formula (2-1-3), formula (2-2-3), formula (2-2-4), formula (2-2-5), and formula (2-2-6), more preferably formula (2-1-2) or formula (2-1-3), and particularly preferably a compound of formula (2-1-2) in which R ^6a is ethyl.

In the case where importance is placed on obtaining a liquid crystal alignment film capable of forming an element having good afterimage characteristics even with a small amount of energy during the alignment treatment (i.e., a liquid crystal alignment agent with high sensitivity), it is preferable to use any one or more compounds selected from the group consisting of formula (2-1-2), formula (2-1-3), formula (2-2-3), formula (2-2-4), formula (2-2-5), formula (2-2-6), formula (2-3-1), and formula (2-3-2), more preferably formula (2-1-2), formula (2-3-1), or formula (2-3-2), and further preferably a compound in which R ^6a is ethyl in formula (2-1-2) or a compound represented by l = 2 to 6 in formula (2-3-1).

When emphasis is placed on obtaining a liquid crystal display element that maintains a high voltage holding ratio even after long-term use (i.e., has excellent VHR reliability), it is preferable to use one or more compounds selected from the group consisting of formulas (2-1-2), (2-1-3), (2-2-1), (2-2-2), (2-2-3), (2-2-4), (2-2-5), and (2-2-6). More preferred are compounds in which l=2 to 6 in formula (2-1-2), (2-1-3), or (2-2-1), and even more preferred are compounds in which R ^6a is ethyl in formula (2-1-2) or compounds in which l=2 to 6 in formula (2-2-1).

When emphasis is placed on obtaining a liquid crystal display element with higher contrast, it is preferable to use one or more compounds selected from the group consisting of formula (2-1-1), formula (2-2-1), and formula (2-2-2), and more preferable is a compound represented by formula (2-1-1) or formula (2-2-1) where l=2 to 6. In that case, the total content of the compounds selected from the group consisting of formula (2-1-1), formula (2-2-1), and formula (2-2-2) in the polymer is preferably 20 mol % to 100 mol %, more preferably 40 mol % to 100 mol %, based on the total amount of diamine in the monomer.

式（Ｂ）において、＊は結合手であり、結合手のベンゼン環に対する結合位置は任意であり、ベンゼン環の置換可能な水素は置換基で置き換えられていてもよい。本発明の液晶配向剤に含まれるポリマーに使用される、光フリース転位を起こす構造を有する化合物の好ましい例としては、下記式（３）が挙げられる。その他に、光フリース転位反応を起こす構造を有する化合物としては、式（ＡＮ－４－３２）～式（ＡＮ－４－３７）、式（ＤＩ－５－３２）、式（ＤＩ－５－３３）、式（ＤＩ－５－３５）、および式（ＤＩ－６－８）～式（ＤＩ－６－１０）で表される化合物が挙げられる。

式（３）中、Ｒ^１及びＲ^２はそれぞれ独立して水素、ハロゲン、炭素数１から６のアルキル、炭素数１～６のハロアルキルまたは炭素数１～６のアルコキシを表す。Ｒ^１とＲ^２は一体となって置換されていてもよいメチレンを形成してもよい。Ｘはそれぞれ独立してハロゲン、炭素数１～６のアルキル、炭素数１～６のハロアルキルまたは炭素数１～６のアルコキシを表し、ｎは０～４の整数を表す。式（ＤＩ－５－３５）におけるｍは、０～１２の整数を表す。 <Compounds Having a Structure That Causes Photo-Fries Rearrangement Reaction>
An example of a structure that causes a photo-Fries rearrangement reaction is a structure having a phenyl ester skeleton. In this specification, the structure having a phenyl ester skeleton refers to a structure represented by the following formula (B).

In formula (B), * is a bond, the bond to the benzene ring may be at any position, and the substitutable hydrogen of the benzene ring may be replaced with a substituent. A preferred example of a compound having a structure that causes the photo-induced Fries rearrangement, which is used in the polymer contained in the liquid crystal aligning agent of the present invention, is represented by the following formula (3). Other examples of compounds having a structure that causes the photo-induced Fries rearrangement reaction include compounds represented by formulas (AN-4-32) to (AN-4-37), (DI-5-32), (DI-5-33), (DI-5-35), and (DI-6-8) to (DI-6-10).

In formula (3), R ¹ and R ² each independently represent hydrogen, halogen, alkyl having 1 to 6 carbon atoms, haloalkyl having 1 to 6 carbon atoms, or alkoxy having 1 to 6 carbon atoms. R ¹ and R ² may be joined together to form an optionally substituted methylene. Each X independently represents halogen, alkyl having 1 to 6 carbon atoms, haloalkyl having 1 to 6 carbon atoms, or alkoxy having 1 to 6 carbon atoms, and n represents an integer of 0 to 4. In formula (DI-5-35), m represents an integer of 0 to 12.

Among these, from the viewpoint of producing a liquid crystal display element with high contrast, it is preferable to use a compound represented by formula (3), and it is more preferable to use a compound in which the amino on each benzene ring in formula (3) is located at the para position relative to the ester.

The total content of the compounds represented by formula (3) in the polymer is preferably 40 mol% to 100 mol%, and more preferably 70 mol% to 100 mol%, based on the total amount of diamines in the monomer.

Specific examples of the compound represented by formula (3) include compounds represented by the following formulas (3-1) to (3-6).

式（Ｃ）において、＊１、＊１′、＊２および＊２′は結合手であり、＊１と＊１′の組および＊２と＊２′の組のどちらか一方または両方は同一のＯと結合していてもよい。すなわち、酸無水物－ＣＯ－Ｏ－ＣＯ－を形成していてもよい。Ｒ^ｂ１、Ｒ^ｂ２、Ｒ^ｂ３およびＲ^ｂ４はそれぞれ独立して１価の有機基である。 <Structure that causes photodecomposition reaction>
An example of a structure that undergoes a photodecomposition reaction is a structure having a cyclobutanetetracarboxylic acid skeleton. In this specification, the structure having a cyclobutanetetracarboxylic acid skeleton refers to a structure represented by the following formula (C).

In formula (C), *1, *1', *2 and *2' are bonds, and either or both of the pair of *1 and *1' and the pair of *2 and *2' may be bonded to the same O. That is, they may form an acid anhydride -CO-O-CO-. R ^b1 , R ^b2 , R ^b3 and R ^b4 are each independently a monovalent organic group.

式（ＰＡ－３）～式（ＰＡ－６）において、Ｒ^１１は独立して、炭素数１～５のアルキルである。 Preferred examples of the compound having a structure that causes a photodecomposition reaction and is used in the polymer contained in the liquid crystal aligning agent of the present invention include compounds represented by the following formulas (PA-1) to (PA-6).

In formulae (PA-3) to (PA-6), R ¹¹ is independently alkyl having 1 to 5 carbon atoms.

式（Ｄ）において、＊は結合手であり、結合手のベンゼン環に対する結合位置は任意であり、ベンゼン環の置換可能な水素は置換基で置き換えられていてもよい。 <Structure that causes photodimerization reaction>
An example of a structure that undergoes a photodimerization reaction is a structure having a cinnamic acid skeleton. In this specification, the structure having a cinnamic acid skeleton refers to a structure represented by the following formula (D).

In formula (D), * represents a bond, and the bond may be attached to the benzene ring at any position, and any substitutable hydrogen atom on the benzene ring may be replaced with a substituent.

式（ＰＤＩ－１２）において、Ｒ^１２は炭素数１～１０のアルキルまたはアルコキシであり、アルキルまたはアルコキシの少なくとも１つの水素はフッ素に置き換えられていてもよい。 Preferred examples of the compound having a structure that causes a photodimerization reaction and is used in the polymer contained in the liquid crystal aligning agent of the present invention include compounds represented by the following formulas (PDI-9) to (PDI-13).

In formula (PDI-12), R ¹² is alkyl or alkoxy having 1 to 10 carbon atoms, and at least one hydrogen of the alkyl or alkoxy may be replaced by fluorine.

Among these, it is preferable to combine it with a compound represented by formula (2) or a compound represented by formula (3).

<Type of polymer>
The polyamic acid and the polyamic acid derivatives will be described in detail below.

Here, the polyamic acid is a polymer synthesized by a polymerization reaction between a tetracarboxylic dianhydride represented by formula (AN) and a diamine represented by formula (DI), and has a constitutional unit represented by formula (PAA). When a liquid crystal alignment agent containing a polyamic acid is heated and baked in the process of forming a liquid crystal alignment film, the polyamic acid is imidized, and a polyimide liquid crystal alignment film having a constitutional unit represented by formula (PI) can be formed.

In formula (AN), formula (PAA), and formula (PI), ^X1 is a tetravalent organic group. In formula (DI), formula (PAA), and formula (PI), ^X2 is a divalent organic group. For the preferred range and specific examples of the tetravalent organic group in ^X1 , reference can be made to the corresponding structure of the tetracarboxylic dianhydride described in this specification. For the preferred range and specific examples of the divalent organic group in ^X2 , reference can be made to the description of the corresponding structure of the diamine or dihydrazide described in this specification.

式（ＰＡＥ）において、Ｘ^１は４価の有機基であり、Ｘ^２は２価の有機基であり、Ｙは独立してアルキルである。Ｘ^１、Ｘ^２の好ましい範囲と具体例については、式（ＰＡＡ）におけるＸ^１、Ｘ^２についての記載を参照することができる。Ｙにおいては、炭素数１～６の直鎖または分岐鎖のアルキルが好ましく、メチル、エチル、プロピル、イソプロピル、ブチル、イソブチル、またはターシャリーブチルがより好ましい。 The polyamic acid derivative is a compound in which a part of the polyamic acid is replaced with another atom or atomic group to modify the properties, and is preferably one which has high solubility in a solvent used for a liquid crystal alignment agent. Specific examples of such polyamic acid derivatives include 1) polyimides in which all amino and carboxy of the polyamic acid are subjected to a dehydration ring-closing reaction, 2) partial polyimides in which a part of the polyamic acid is subjected to a dehydration ring-closing reaction, 3) polyamic acid esters in which the carboxy of the polyamic acid is converted into an ester, 4) polyamic acid-polyamide copolymers obtained by replacing a part of the acid dianhydride contained in a tetracarboxylic acid dianhydride compound with an organic dicarboxylic acid and reacting the resulting mixture, and 5) polyamideimides in which a part or all of the polyamic acid-polyamide copolymer is subjected to a dehydration ring-closing reaction. Among these derivatives, for example, polyimides can be exemplified by those having a structural unit represented by the above formula (PI), and polyamic acid esters can be exemplified by those having a structural unit represented by the following formula (PAE).

In formula (PAE), ^X1 is a tetravalent organic group, ^X2 is a divalent organic group, and Y is independently an alkyl. For preferred ranges and specific examples of ^X1 and ^X2 , the description of ^X1 and ^X2 in formula (PAA) can be referred to. Y is preferably a linear or branched alkyl having 1 to 6 carbon atoms, and more preferably methyl, ethyl, propyl, isopropyl, butyl, isobutyl, or tertiary butyl.

When the polyamic acid is converted into a polyimide, which is a polyamic acid derivative, the obtained polyamic acid solution can be subjected to an imidization reaction at a temperature of 20 to 150°C together with an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride, which is a dehydrating agent, and a tertiary amine such as triethylamine, pyridine, or collidine, which is a dehydration ring-closing catalyst, to obtain a polyimide. Alternatively, the polyamic acid can be precipitated from the obtained polyamic acid solution using a large amount of a poor solvent (an alcohol-based solvent such as methanol, ethanol, or isopropanol, or a glycol-based solvent), and the precipitated polyamic acid can be subjected to an imidization reaction at a temperature of 20 to 150°C together with the above-mentioned dehydrating agent and dehydration ring-closing catalyst in a solvent such as toluene or xylene, to obtain a polyimide.

In the imidization reaction, the ratio of the dehydrating agent to the dehydration ring-closing catalyst is preferably 0.1 to 10 (molar ratio). The total amount of the dehydrating agent and the dehydration ring-closing catalyst used is preferably 1.5 to 10 times the total molar amount of the tetracarboxylic dianhydride used in the synthesis of the polyamic acid. The degree of imidization can be controlled by adjusting the amount of the dehydrating agent and catalyst used in this imidization reaction, the reaction temperature, and the reaction time, thereby obtaining a partial polyimide in which only a portion of the polyamic acid is imidized. The obtained polyimide can be separated from the solvent used in the reaction and redissolved in another solvent and used as a liquid crystal alignment agent, or it can be used as a liquid crystal alignment agent without separating it from the solvent.

Polyamic acid esters can be obtained by a synthesis method of reacting polyamic acid with a hydroxyl group-containing compound, a halide, an epoxy-containing compound, or the like, or by a synthesis method of reacting a tetracarboxylic acid diester or a tetracarboxylic acid diester dichloride derived from a tetracarboxylic acid dianhydride with a diamine. Tetracarboxylic acid diesters derived from tetracarboxylic acid dianhydrides can be obtained, for example, by reacting a tetracarboxylic acid dianhydride with two equivalents of an alcohol to open the ring, and tetracarboxylic acid diester dichlorides can be obtained by reacting a tetracarboxylic acid diester with two equivalents of a chlorinating agent (e.g., thionyl chloride, etc.). The polyamic acid ester may have only an amic acid ester structure, or may be a partial ester in which an amic acid structure and an amic acid ester structure coexist.

The polyamic acid or its derivative of the present invention can be produced in the same manner as known polyamic acids or their derivatives used in forming polyimide films. The total amount of tetracarboxylic acid derivatives charged is preferably 0.9 to 1.1 moles per mole of the total of diamines.

The liquid crystal alignment agent of the present invention may contain only one of these polyamic acids, polyamic acid esters, and polyimides obtained by imidizing these, or may contain two or more of them.

The molecular weight of the polyamic acid or its derivative of the present invention is preferably 5,000 to 500,000, more preferably 5,000 to 50,000, in terms of polystyrene equivalent weight average molecular weight (Mw). The molecular weight of the polyamic acid or its derivative can be determined by measurement using gel permeation chromatography (GPC).

The presence of the polyamic acid or its derivative of the present invention can be confirmed by analyzing the solid content obtained by precipitating the polyamic acid or its derivative with a large amount of poor solvent using IR (infrared spectroscopy) or NMR (nuclear magnetic resonance analysis). The monomers used can also be confirmed by analyzing an organic solvent extract of the decomposition product of the polyamic acid or its derivative with an aqueous solution of a strong alkali such as KOH or NaOH using GC (gas chromatography), HPLC (high performance liquid chromatography) or GC-MS (gas chromatography mass spectrometry).

<Other tetracarboxylic acid derivatives>
The tetracarboxylic acid derivative other than the compound represented by formula (1) used as the raw material for the polymer of the present invention can be selected from known tetracarboxylic acid derivatives without any limitation.

Other examples of tetracarboxylic dianhydrides are given below. These tetracarboxylic dianhydrides may be converted into tetracarboxylic diesters or tetracarboxylic diester dichlorides and used as raw materials for polymers.

Such tetracarboxylic dianhydrides may belong to either the aromatic system (including heteroaromatic ring systems) in which the dicarboxylic anhydride is directly bonded to the aromatic ring, or the aliphatic system (including heterocyclic ring systems) in which the dicarboxylic anhydride is not directly bonded to the aromatic ring.

Examples of such tetracarboxylic dianhydrides include compounds represented by the following formulas (AN-1) to (AN-9), (AN-11), (AN-12), (AN-15), (AN-10-1), (AN-10-2), and (AN-16-1) to (AN-16-15).

式（ＡＮ－１）において、Ｇ^１１は単結合、炭素数１～１２のアルキレン、１，４－フェニレン、または１，４－シクロヘキシレンである。Ｘ^１１は独立して単結合または－ＣＨ_２－である。Ｇ^１２は独立して下記の３価の基のいずれかである。

Ｇ^１２が＞ＣＨ－であるとき、＞ＣＨ－の水素はメチルで置換されていてもよい。Ｇ^１２が＞Ｎ－であるとき、Ｇ^１１は単結合および－ＣＨ_２－であることはなく、Ｘ^１１は単結合であることはない。
Ｒ^１１は独立して水素またはメチルである。 [Tetracarboxylic acid dianhydride represented by formula (AN-1)]

In formula (AN-1), G ¹¹ is a single bond, an alkylene having 1 to 12 carbon atoms, 1,4-phenylene, or 1,4-cyclohexylene. ^{X 11} is independently a single bond or —CH ₂ —. G ¹² is independently any of the following trivalent groups:

When G ¹² is >CH--, the hydrogen of >CH-- may be substituted with methyl. When G ¹² is >N--, G ¹¹ is not a single bond or -CH ₂ -, and X ¹¹ is not a single bond.
R ¹¹ is independently hydrogen or methyl.

式（ＡＮ－１－２）および（ＡＮ－１－１４）において、ｍはそれぞれ独立して１～１２の整数である。 Examples of the tetracarboxylic dianhydride represented by formula (AN-1) include the compounds represented by the following formulas (AN-1-1) to (AN-1-15).

In formulas (AN-1-2) and (AN-1-14), each m is independently an integer of 1 to 12.

式（ＡＮ－２）において、Ｒ^６１は独立して、水素、炭素数１～５のアルキル、またはフェニルである。 [Tetracarboxylic acid dianhydride represented by formula (AN-2)]

In formula (AN-2), R ⁶¹ is independently hydrogen, alkyl having 1 to 5 carbon atoms, or phenyl.

Examples of the tetracarboxylic dianhydride represented by formula (AN-2) include the compounds represented by the following formulas (AN-2-1) to (AN-2-3).

式（ＡＮ－３）において、環Ａ^１１はシクロヘキサン環またはベンゼン環である。 [Tetracarboxylic acid dianhydride represented by formula (AN-3)]

In formula (AN-3), ring A ¹¹ is a cyclohexane ring or a benzene ring.

Examples of the tetracarboxylic dianhydride represented by formula (AN-3) include compounds represented by the following formulas (AN-3-1) and (AN-3-2).

式（ＡＮ－４）において、Ｇ^１３は単結合、－（ＣＨ_２）_ｍ－、－Ｏ－、－Ｓ－、－Ｃ（ＣＨ_３）_２－、－ＳＯ_２－、－ＣＯ－、－Ｃ（ＣＦ_３）_２－、または下記式（Ｇ１３－１）で表される２価の基であり、ｍは１～１２の整数である。環Ａ^１１はそれぞれ独立してシクロヘキサン環またはベンゼン環である。Ｇ^１３は環Ａ^１１の任意の位置に結合してよい。

式（Ｇ１３－１）において、Ｇ^１３ａおよびＧ^１３ｂはそれぞれ独立して、単結合、－Ｏ－、－ＣＯＮＨ－、または－ＮＨＣＯ－で表される２価の基である。フェニレンは、１，４－フェニレンまたは１，３－フェニレンであることが好ましい。 [Tetracarboxylic acid dianhydride represented by formula (AN-4)]

In formula (AN-4), G ¹³ is a single bond, -(CH ₂ ) _m -, -O-, -S-, -C(CH ₃ ) ₂ -, -SO ₂ -, -CO-, -C(CF ₃ ) ₂ -, or a divalent group represented by the following formula (G13-1), where m is an integer of 1 to 12. Each ring A ¹¹ is independently a cyclohexane ring or a benzene ring. G ¹³ may be bonded to any position of ring A ¹¹ .

In formula (G13-1), G ^13a and G ^13b each independently represent a divalent group represented by a single bond, -O-, -CONH-, or -NHCO-, and the phenylene is preferably 1,4-phenylene or 1,3-phenylene.

式（ＡＮ－４－１７）において、ｍは１～１２の整数である。 Examples of the tetracarboxylic dianhydride represented by formula (AN-4) include the compounds represented by the following formulas (AN-4-1) to (AN-4-32).

In formula (AN-4-17), m is an integer from 1 to 12.

式（ＡＮ－５）において、Ｒ^１１は独立して水素またはメチルである。２つのＲ^１１のうちベンゼン環におけるＲ^１１は、ベンゼン環の置換可能な位置のいずれかに結合する。 [Tetracarboxylic acid dianhydride represented by formula (AN-5)]

In formula (AN-5), R ¹¹ is independently hydrogen or methyl. Of the two R ¹¹ , the R ¹¹ in the benzene ring is bonded to any substitutable position of the benzene ring.

Examples of the tetracarboxylic dianhydride represented by formula (AN-5) include the compounds represented by the following formulas (AN-5-1) to (AN-5-3).

式（ＡＮ－６）において、Ｘ^１１は独立して単結合または－ＣＨ_２－である。Ｘ^１２は－ＣＨ_２－、－ＣＨ_２ＣＨ_２－または－ＣＨ＝ＣＨ－である。ｎは１または２である。ｎが２であるとき、２つのＸ^１２は互いに同一であっても異なっていてもよい。 [Tetracarboxylic acid dianhydride represented by formula (AN-6)]

In formula (AN-6), X ¹¹ is independently a single bond or -CH ₂ -. X ¹² is -CH ₂ -, -CH ₂ CH ₂ - or -CH=CH-. n is 1 or 2. When n is 2, two X ¹² may be the same or different.

Examples of the tetracarboxylic dianhydride represented by formula (AN-6) include the compounds represented by the following formulas (AN-6-1) to (AN-6-12).

式（ＡＮ－７）において、Ｘ^１１は単結合または－ＣＨ_２－である。 [Tetracarboxylic acid dianhydride represented by formula (AN-7)]

In formula (AN-7), X ¹¹ is a single bond or —CH ₂ —.

Examples of the tetracarboxylic dianhydride represented by formula (AN-7) include compounds represented by the following formulas (AN-7-1) and (AN-7-2).

式（ＡＮ－８）において、Ｘ^１１は単結合または－ＣＨ_２－である。Ｒ^１２は水素、メチル、エチル、またはフェニルである。環Ａ^１２はシクロヘキサン環またはシクロヘキセン環である。 [Tetracarboxylic acid dianhydride represented by formula (AN-8)]

In formula (AN-8), X ¹¹ is a single bond or -CH ₂ -. R ¹² is hydrogen, methyl, ethyl or phenyl. Ring A ¹² is a cyclohexane ring or a cyclohexene ring.

Examples of the tetracarboxylic dianhydride represented by formula (AN-8) include compounds represented by the following formulas (AN-8-1) and (AN-8-2).

式（ＡＮ－９）において、ｒはそれぞれ独立して０または１である。 [Tetracarboxylic acid dianhydride represented by formula (AN-9)]

In formula (AN-9), each r is independently 0 or 1.

Examples of the tetracarboxylic dianhydride represented by formula (AN-9) include the compounds represented by the following formulas (AN-9-1) to (AN-9-3).

[Tetracarboxylic acid dianhydrides represented by formulas (AN-10-1) and (AN-10-2)]

式（ＡＮ－１１）において、環Ａ^１１は独立してシクロヘキサン環またはベンゼン環である。 [Tetracarboxylic acid dianhydride represented by formula (AN-11)]

In formula (AN-11), ring A ¹¹ is independently a cyclohexane ring or a benzene ring.

Examples of the tetracarboxylic dianhydride represented by formula (AN-11) include the compounds represented by the following formulas (AN-11-1) to (AN-11-3).

式（ＡＮ－１２）において、環Ａ^１１はそれぞれ独立してシクロヘキサン環またはベンゼン環である。 [Tetracarboxylic acid dianhydride represented by formula (AN-12)]

In formula (AN-12), each ring A ¹¹ independently represents a cyclohexane ring or a benzene ring.

Examples of the tetracarboxylic dianhydride represented by formula (AN-12) include the compounds represented by the following formulas (AN-12-1) to (AN-12-3).

式（ＡＮ－１５）において、ｗは１～１０の整数である。 [Tetracarboxylic acid dianhydride represented by formula (AN-15)]

In formula (AN-15), w is an integer of 1 to 10.

Examples of the tetracarboxylic dianhydride represented by formula (AN-15) include compounds represented by the following formulas (AN-15-1) to (AN-15-3).

[Tetracarboxylic acid dianhydrides represented by formulas (AN-16-1) to (AN-16-15)]
Other tetracarboxylic dianhydrides include the compounds represented by the following formulae (AN-16-1) to (AN-16-15).

Among the above tetracarboxylic dianhydrides, preferred materials for improving the properties of the liquid crystal alignment film described below will be described. When emphasis is placed on further improving the liquid crystal alignment properties, compounds represented by formula (AN-1-2), formula (AN-4-17), formula (AN-4-21), or formula (AN-4-29) are more preferred, and in formula (AN-1-2), m is preferably 4 to 8, and in formula (AN-4-17), m is preferably 4 to 8.

When emphasis is placed on improving the transmittance of the liquid crystal display element, compounds represented by formula (AN-1-1), (AN-1-2), (AN-2-1), (AN-3-1), (AN-4-17), (AN-4-30), (AN-5-1), (AN-7-2), (AN-10-1), (AN-16-3), or (AN-16-4) are preferred, and among these, in formula (AN-1-2), m=4 or 8 is preferred, and in formula (AN-4-17), m=4 to 8 is preferred, with m=8 being more preferred.

When emphasis is placed on improving the VHR of the liquid crystal display element, compounds represented by formula (AN-1-1), (AN-1-2), (AN-3-1), (AN-4-17), (AN-4-30), (AN-7-2), (AN-10-1), (AN-16-3), (AN-16-4), or (AN-2-1) are preferred, and in formula (AN-1-2), m=4 or 8 is preferred, and in formula (AN-4-17), m=4 or 8 is preferred, with m=8 being more preferred.

One effective method for preventing image sticking is to improve the relaxation speed of the residual charge (residual DC) in the liquid crystal alignment film by reducing the volume resistance of the liquid crystal alignment film. When this objective is important, compounds represented by formula (AN-1-13), formula (AN-3-2), formula (AN-4-21), formula (AN-4-29), or formula (AN-11-3) are preferred.

<Other diamines>
Diamines other than the compounds represented by formula (2) or (3) used as raw materials for the polymer of the present invention can be selected from known diamines without any limitation.

Diamines can be divided into two types based on their structure. That is, when the skeleton connecting the two amino groups is viewed as the main chain, there are diamines that have groups branching from the main chain, i.e., side chain groups, and diamines that do not have side chain groups. In the following explanation, diamines that have such side chain groups may be referred to as side chain type diamines. And diamines that do not have such side chain groups may be referred to as non-side chain type diamines. The side chain groups are groups that have the effect of increasing the pretilt angle.
By appropriately using the non-side chain type diamine and the side chain type diamine, it is possible to meet the pretilt angle required for each.

It is preferable to use side chain diamines in combination to the extent that the characteristics of the present invention are not impaired. It is also preferable to selectively use side chain diamines and non-side chain diamines in order to improve characteristics such as vertical alignment properties for liquid crystals, VHR, and afterimage characteristics.

上記の式（ＤＩ－１）において、Ｇ^２０は、－ＣＨ_２－または式（ＤＩ－１－ａ）で表される基である。Ｇ^２０が－ＣＨ_２－であるとき、ｍ個の－ＣＨ_２－の少なくとも１つは－ＮＨ－または－Ｏ－に置き換えられてもよく、ｍ個の－ＣＨ_２－の少なくとも１つの水素は水酸基またはメチルで置換されてもよい。ｍは１～１２の整数である。ＤＩ－１におけるｍが２以上であるとき、複数のＧ^２０は互いに同一であっても異なっていてもよい。ただし、Ｇ^２０が式（ＤＩ－１－ａ）であるとき、ｍは１である。

式（ＤＩ－１－ａ）において、ｖはそれぞれ独立して１～６の整数である。 Known diamines having no side chains are shown in the following formulas (DI-1) to (DI-16).

In the above formula (DI-1), G ²⁰ is -CH ₂ - or a group represented by formula (DI-1-a). When G ²⁰ is -CH ₂ -, at least one of the m -CH ₂ - may be replaced by -NH- or -O-, and at least one hydrogen of the m -CH ₂ - may be replaced by a hydroxyl group or methyl. m is an integer of 1 to 12. When m in DI-1 is 2 or more, multiple G ²⁰ may be the same or different from each other. However, when G ²⁰ is formula (DI-1-a), m is 1.

In formula (DI-1-a), each v is independently an integer of 1 to 6.

In formulae (DI-3), (DI-6) and (DI-7), G ²¹ independently represents a single bond, -NH-, -NCH ₃ -, -O-, -S-, -S-S-, -SO ₂ -, -CO-, -COO-, -CONCH ₃ -, -CONH-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -(CH ₂ ) _m -, -O-(CH ₂ ) _m -O-, -N(CH ₃ )-(CH ₂ ) _k -N(CH ₃ )-, -(O-C ₂ H ₄ ) _m -O-, -O-CH ₂ -C(CF ₃ ) ₂ -CH ₂ -O-, -O-CO-(CH ₂ ) _m -CO-O-, -CO-O-(CH ₂ ) _m -O-CO-, -( _CH2 ) _m -NH-( _CH2 ) _m- , _-CO- ( _CH2 ) _k -NH-( _CH2 ) _k- , -(NH-( _CH2 ) _m ) _k -NH-, _{-CO-C3H6- (} NH- _C3H6 ) _n -CO-, or -S-( _CH2 ) _m -S-, wherein m is independently an integer of 1 to 12, k is an integer of 1 to 5, and n is 1 or 2.
In formula (DI-4), s independently represents an integer of 0 to 2.

In formula (DI-5), G ³³ is a single bond, -NH-, -NCH ₃ -, -O-, -S-, -S-S-, -SO ₂ -, -CO-, -COO-, -CONCH ₃ -, -CONH-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -(CH ₂ ) _m -, -O-(CH 2 ) _m -O- _, -N(CH ₃ )-(CH ₂ ) _k -N(CH ₃ )-, -(O-C ₂ H ₄ ) _m -O-, -O-CH ₂ -C(CF ₃ ) ₂ -CH ₂ -O-, -O-CO-(CH ₂ ) _m -CO-O-, -CO-O-(CH ₂ ) _m -O-CO-, -(CH ₂ ) _m -NH-( _CH2 ) _m- , -CO-( _CH2 ) _k -NH-( _CH2 ) _k- , -(NH-( _CH2 ) _m ) _k -NH- _, -CO- _C3H6- (NH- _C3H6 ) _n -CO-, or -S-( _CH2 ) _m -S-, -N( _Boc ) _- (CH2) _e -N(Boc)-, -NH-( _CH2 ) _e -N(Boc)-, -N(Boc)-( _CH2 ) _e- , -( _CH2 ) _m -N(Boc)-CONH-( _CH2 ) _m- , -( _CH2 ) _m -N(Boc)-( _CH2 ) _m -, or a group represented by the following formula (DI-5-a) or (DI-5-b), where m is independently an integer of 1 to 12, k is an integer of 1 to 5, e is an integer of 2 to 10, and n is 1 or 2. Boc is t-butoxycarbonyl.

In formulae (DI-6) and (DI-7), G ²² independently represents a single bond, —O—, —S—, —CO—, —C(CH ₃ ) ₂ —, —C(CF ₃ ) ₂ —, or an alkylene having 1 to 10 carbon atoms.

At least one hydrogen atom on the cyclohexane ring and the benzene ring in formulae (DI-2) to (DI-7) may be substituted with -F, -Cl, an alkylene having 1 to 3 carbon atoms, -OCH ₃ , -OH, -CF ₃ , -CO ₂ H, -CONH ₂ , -NHC ₆ H ₅ , phenyl, or benzyl; in addition, in formula (DI-4), at least one hydrogen atom on the cyclohexane ring and the benzene ring may be substituted with one selected from the group of groups represented by any of the following formulae (DI-4-a) to (DI-4-i); and in formula (DI-5), when G ³³ is a single bond, at least one hydrogen atom on the cyclohexane ring and the benzene ring may be substituted with NHBoc or N(Boc) ₂ .

式（ＤＩ－４－ａ）および式（ＤＩ－４－ｂ）において、Ｒ^２０は独立して水素または－ＣＨ_３である。式（ＤＩ－４－ｆ）および式（ＤＩ－４－ｇ）において、ｍはそれぞれ独立して０～１２の整数であり、Ｂｏｃはｔ－ブトキシカルボニルである。 A group that is not fixed to a carbon atom constituting a ring indicates that the bonding position in the ring is arbitrary. And, the bonding position of _-NH2 to the cyclohexane ring or benzene ring is arbitrary except for the bonding position of G ²¹ , G ²² or G ³³ .

In formulae (DI-4-a) and (DI-4-b), R ²⁰ is independently hydrogen or -CH _3. In formulae (DI-4-f) and (DI-4-g), each m is independently an integer of 0 to 12, and Boc is t-butoxycarbonyl.

式（ＤＩ－５－ａ）において、ｑはそれぞれ独立して０～６の整数である。Ｒ^４４は水素、－ＯＨ、炭素数１～６のアルキル、または炭素数１～６のアルコキシである。

In formula (DI-5-a), each q is independently an integer of 0 to 6. R ⁴⁴ is hydrogen, —OH, alkyl having 1 to 6 carbon atoms, or alkoxy having 1 to 6 carbon atoms.

式（ＤＩ－１１）において、ｒは０または１である。式（ＤＩ－８）～式（ＤＩ－１１）において、環に結合する－ＮＨ_２の結合位置は、任意の位置である。

In formula (DI-11), r is 0 or 1. In formulas (DI-8) to (DI-11), the bonding position of --NH ₂ bonded to the ring is any position.

式（ＤＩ－１２）において、Ｒ^２１およびＲ^２２は、それぞれ独立して炭素数１～３のアルキルまたはフェニルであり、Ｇ^２３は独立して炭素数１～６のアルキレン、フェニレンまたはアルキルで置換されたフェニレンであり、ｗは１～１０の整数である。
式（ＤＩ－１３）において、Ｒ^２３は独立して炭素数１～５のアルキル、炭素数１～５のアルコキシまたは－Ｃｌであり、ｐは独立して０～３の整数であり、ｑは０～４の整数である。
式（ＤＩ－１４）において、環Ｂは単環の複素環式芳香族基であり、Ｒ^２４は水素、－Ｆ、－Ｃｌ、炭素数１～６のアルキル、アルコキシ、アルケニル、またはアルキニルであり、ｑは独立して０～４の整数である。ｑが２以上であるとき、複数のＲ^２４は互いに同一であっても異なっていてもよい。
式（ＤＩ－１５）において、環Ｃは複素環式芳香族基または複素環式脂肪族基である。
式（ＤＩ－１６）において、Ｇ^２４は単結合、炭素数２～６のアルキレンまたは１，４－フェニレンであり、ｒは０または１である。そして、環を構成する炭素に結合位置が固定されていない基は、その環における結合位置が任意であることを示す。式（ＤＩ－１３）～式（ＤＩ－１６）において、環に結合する－ＮＨ_２の結合位置は、任意の位置である。

In formula (DI-12), R ²¹ and R ²² each independently represent an alkyl group having 1 to 3 carbon atoms or a phenyl group; G ²³ independently represents an alkylene group having 1 to 6 carbon atoms, a phenylene group or a phenylene group substituted with an alkyl group; and w represents an integer of 1 to 10.
In formula (DI-13), R ²³ independently represents alkyl having 1 to 5 carbon atoms, alkoxy having 1 to 5 carbon atoms or -Cl; p independently represents an integer of 0 to 3; and q independently represents an integer of 0 to 4.
In formula (DI-14), ring B is a monocyclic heteroaromatic group, R ²⁴ is hydrogen, -F, -Cl, alkyl, alkoxy, alkenyl, or alkynyl having 1 to 6 carbon atoms, and q is independently an integer of 0 to 4. When q is 2 or more, multiple R ^24s may be the same or different.
In formula (DI-15), ring C is a heterocyclic aromatic group or a heterocyclic aliphatic group.
In formula (DI-16), G ²⁴ is a single bond, an alkylene having 2 to 6 carbon atoms or 1,4-phenylene, and r is 0 or 1. A group that is not bonded to a carbon constituting a ring indicates that the bonding position in the ring is arbitrary. In formulas (DI-13) to (DI-16), the bonding position of -NH ₂ bonded to the ring is arbitrary.

式（ＤＩ－１－７）および式（ＤＩ－１－８）において、ｋはそれぞれ独立して、１～３の整数である。式（ＤＩ－１－９）において、ｖはそれぞれ独立して１～６の整数である。 Examples of the diamine represented by formula (DI-1) are shown in the following formulas (DI-1-1) to (DI-1-9).

In formula (DI-1-7) and formula (DI-1-8), k is independently an integer of 1 to 3. In formula (DI-1-9), v is independently an integer of 1 to 6.

Examples of the diamines represented by formulas (DI-2) to (DI-3) are shown in the following formulas (DI-2-1), (DI-2-2), and (DI-3-1) to (DI-3-3).

式（ＤＩ－４－２０）および（ＤＩ－４－２１）において、ｍはそれぞれ独立して１～１２の整数である。

Examples of the diamine represented by formula (DI-4) are shown in the following formulas (DI-4-1) to (DI-4-27).

In formulas (DI-4-20) and (DI-4-21), each m is independently an integer of 1 to 12.

式（ＤＩ－５－１）において、ｍは１～１２の整数である。 Examples of the diamine represented by formula (DI-5) are shown in the following formulas (DI-5-1) to (DI-5-50).

In formula (DI-5-1), m is an integer of 1 to 12.

式（ＤＩ－５－１２）および式（ＤＩ－５－１３）において、ｍはそれぞれ独立して１～１２の整数である。

In formulae (DI-5-12) and (DI-5-13), each m is independently an integer of 1 to 12.

式（ＤＩ－５－１６）において、ｖは１～６の整数である。

In formula (DI-5-16), v is an integer of 1 to 6.

式（ＤＩ－５－３０）において、ｋは１～５の整数である。

In formula (DI-5-30), k is an integer of 1 to 5.

式（ＤＩ－５－３５）～式（ＤＩ－５－３７）、および式（ＤＩ－５－３９）において、ｍはそれぞれ独立して１～１２の整数であり、式（ＤＩ－５－３８）および式（ＤＩ－５－３９）において、ｋはそれぞれ独立して１～５の整数であり、式（ＤＩ－５－４０）において、ｎは１または２である。

In formulas (DI-5-35) to (DI-5-37) and (DI-5-39), m each independently represents an integer of 1 to 12; in formulas (DI-5-38) and (DI-5-39), k each independently represents an integer of 1 to 5; and in formula (DI-5-40), n is 1 or 2.

式（ＤＩ－５－４２）～式（ＤＩ－５－４４）において、ｅはそれぞれ独立して２～１０の整数であり、式（ＤＩ－５－４５）においてＲ^４３は水素、－ＮＨＢｏｃ、または－Ｎ（Ｂｏｃ）_２である。式（ＤＩ－５－４２）～式（ＤＩ－５－４４）において、Ｂｏｃはｔ－ブトキシカルボニルである。

In formulae (DI-5-42) to (DI-5-44), e is independently an integer of 2 to 10, and in formula (DI-5-45), R ⁴³ is hydrogen, —NHBoc, or —N(Boc) _2. In formulae (DI-5-42) to (DI-5-44), Boc is t-butoxycarbonyl.

Examples of the diamine represented by formula (DI-6) are shown in the following formulas (DI-6-1) to (DI-6-7).

式（ＤＩ－７－３）および式（ＤＩ－７－４）において、ｍはそれぞれ独立して１～１２の整数であり、ｎは独立して１または２である。 Examples of the diamine represented by formula (DI-7) are shown in the following formulas (DI-7-1) to (DI-7-11).

In formulae (DI-7-3) and (DI-7-4), m is each independently an integer of 1 to 12; n is independently 1 or 2.

Examples of the diamine represented by formula (DI-8) are shown in the following formulas (DI-8-1) to (DI-8-4).

Examples of the diamine represented by formula (DI-9) are shown in the following formulas (DI-9-1) to (DI-9-3).

Examples of the diamine represented by formula (DI-10) are shown in the following formulas (DI-10-1) and (DI-10-2).

Examples of the diamine represented by formula (DI-11) are shown in the following formulas (DI-11-1) to (DI-11-3).

An example of the diamine represented by formula (DI-12) is shown in the following formula (DI-12-1).

Examples of the diamine represented by formula (DI-13) are shown in the following formulas (DI-13-1) to (DI-13-13).

Examples of the diamine represented by formula (DI-14) are shown in the following formulas (DI-14-1) to (DI-14-9).

Examples of the diamine represented by formula (DI-15) are shown in the following formulas (DI-15-1) to (DI-15-12).

An example of the diamine represented by formula (DI-16) is shown in the following formula (DI-16-1).

式（ＤＩＨ－１）において、Ｇ^２５は単結合、炭素数１～２０のアルキレン、－ＣＯ－、－Ｏ－、－Ｓ－、－ＳＯ_２－、－Ｃ（ＣＨ_３）_２－、または－Ｃ（ＣＦ_３）_２－である。
式（ＤＩＨ－２）において、環Ｄはシクロヘキサン環、ベンゼン環またはナフタレン環であり、この基の少なくとも１つの水素はメチル、エチル、またはフェニルで置換されてもよい。
式（ＤＩＨ－３）において、環Ｅはそれぞれ独立してシクロヘキサン環、またはベンゼン環であり、この基の少なくとも１つの水素はメチル、エチル、またはフェニルで置換されてもよい。複数の環Ｅは互いに同一であっても異なっていてもよい。Ｙは単結合、炭素数１～２０のアルキレン、－ＣＯ－、－Ｏ－、－Ｓ－、－ＳＯ_２－、－Ｃ（ＣＨ_３）_２－、または－Ｃ（ＣＦ_３）_２－である。
式（ＤＩＨ－２）および式（ＤＩＨ－３）において、環に結合する－ＣＯＮＨＮＨ_２の結合位置は、任意の位置である。 Next, the dihydrazide used as the raw material for the polymer of the present invention will be described. Known dihydrazides having no side chains include compounds represented by any of the following formulas (DIH-1) to (DIH-3).

In formula (DIH-1), G ²⁵ is a single bond, an alkylene having 1 to 20 carbon atoms, -CO-, -O-, -S-, -SO ₂ -, -C(CH ₃ ) ₂ - or -C(CF ₃ ) ₂ -.
In formula (DIH-2), ring D is a cyclohexane ring, a benzene ring or a naphthalene ring, and at least one hydrogen of this group may be substituted with methyl, ethyl, or phenyl.
In formula (DIH-3), each ring E is independently a cyclohexane ring or a benzene ring, and at least one hydrogen atom in this group may be substituted with methyl, ethyl, or phenyl. Multiple rings E may be the same or different. Y is a single bond, an alkylene having 1 to 20 carbon atoms, -CO-, -O-, -S-, -SO ₂ -, -C(CH ₃ ) ₂ -, or -C(CF ₃ ) ₂ -.
In the formula (DIH-2) and the formula (DIH-3), the bonding position of --CONHNH ₂ bonded to the ring may be any position.

式（ＤＩＨ－１－２）において、ｍは１～１２の整数である。 Examples of the compounds represented by any of formulas (DIH-1) to (DIH-3) are shown in the following formulas (DIH-1-1), (DIH-1-2), (DIH-2-1) to (DIH-2-3), and (DIH-3-1) to (DIH-3-6).

In formula (DIH-1-2), m is an integer of 1 to 12.

Diamines suitable for increasing the pretilt angle will now be described. The compound of the present invention can be suitably used as a liquid crystal aligning agent for use in a horizontal electric field type liquid crystal display element, but it is also possible to increase the pretilt angle by using it in combination with the following diamines. Diamines having a side chain group suitable for increasing the pretilt angle include diamines represented by any of formulas (DI-31) to (DI-35) and formulas (DI-36-1) to (DI-36-8).

In formula (DI-31), G ²⁶ is a single bond, -O-, -COO-, -OCO-, -CO-, -CONH-, -CH ₂ O-, -OCH ₂ -, -CF ₂ O-, -OCF ₂ -, or -(CH ₂ ) _ma -, where ma is an integer of 1 to 12. Preferred examples of G ²⁶ are a single bond, -O-, -COO-, -OCO-, -CH ₂ O-, or an alkylene having 1 to 3 carbon atoms, and particularly preferred examples are a single bond, -O-, -COO-, -OCO-, -CH 2 O-, -CH ₂ -, or -CH ₂ CH ₂ -. ^{R 25} is an alkyl having 3 to 30 carbon atoms, phenyl, a group having a steroid skeleton, or _a group represented by the following formula (DI-31-a). In this alkyl, at least one hydrogen may be replaced by -F, and at least one -CH ₂ - may be replaced by -O-, -CH=CH- or -C≡C-. This phenyl hydrogen may be replaced by -F, -CH ₃ , -OCH ₃ , -OCH ₂ F, -OCHF _{2 ,} -OCF _3, alkyl having 3 to 30 carbon atoms, or alkoxy having 3 to 30 carbon atoms. The bonding position of -NH ₂ bonded to the benzene ring indicates any position in the ring, but the bonding position is preferably the meta position or para position. That is, when the bonding position of the group "R ²⁵ -G ²⁶ -" is the 1st position, the two bonding positions are preferably the 3rd and 5th positions, or the 2nd and 5th positions.

式（ＤＩ－３１－ａ）において、Ｇ^２７、Ｇ^２８およびＧ^２９は結合基であり、これらは、それぞれ独立して単結合、または炭素数１～１２のアルキレンであり、このアルキレンの１以上の－ＣＨ_２－は、－Ｏ－、－ＣＯＯ－、－ＯＣＯ－、－ＣＯＮＨ－、または－ＣＨ＝ＣＨ－で置換されていてもよい。環Ｂ^２１、環Ｂ^２２、環Ｂ^２３および環Ｂ^２４は、それぞれ独立して１，４－フェニレン、１，４－シクロへキシレン、１，３－ジオキサン－２，５－ジイル、ピリミジン－２，５－ジイル、ピリジン－２，５－ジイル、ナフタレン－１，５－ジイル、ナフタレン－２，７－ジイルまたはアントラセン－９，１０－ジイルであり、環Ｂ^２１、環Ｂ^２２、環Ｂ^２３および環Ｂ^２４において、少なくとも１つの水素は－Ｆまたは－ＣＨ_３で置換されてもよく、ｓ、ｔ、およびｕは、それぞれ独立して０～２の整数であって、これらの合計は１～５であり、ｓ、ｔ、またはｕが２であるとき、それぞれの括弧内の２つの結合基は同じであっても異なってもよく、そして、２つの環は同じであっても異なっていてもよい。Ｒ^２６は水素、－Ｆ、－ＯＨ、炭素数１～３０のアルキル、炭素数１～３０のフッ素置換アルキル、炭素数１～３０のアルコキシ、－ＣＮ、－ＯＣＨ_２Ｆ、－ＯＣＨＦ_２、または－ＯＣＦ_３であり、この炭素数１～３０のアルキルの少なくとも１つの－ＣＨ_２－は下記式（ＤＩ－３１－ｂ）で表される２価の基で置換されていてもよい。

式（ＤＩ－３１－ｂ）において、Ｒ^２７およびＲ^２８は、それぞれ独立して炭素数１～３のアルキルであり、ｖは１～６の整数である。Ｒ^２６の好ましい例は炭素数１～３０のアルキルおよび炭素数１～３０のアルコキシである。

In formula (DI-31-a), G ²⁷ , G ²⁸ and G ²⁹ are bonding groups, each of which independently represents a single bond or an alkylene having 1 to 12 carbon atoms, and one or more -CH ₂ - of the alkylene may be replaced by -O-, -COO-, -OCO-, -CONH- or -CH═CH-. Ring B ²¹ , ring B ²² , ring B ²³ and ring B ²⁴ are each independently 1,4-phenylene, 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, pyrimidine-2,5-diyl, pyridine-2,5-diyl, naphthalene-1,5-diyl, naphthalene-2,7-diyl or anthracene-9,10-diyl; in ring B ²¹ , ring B ²² , ring B ²³ and ring B ²⁴ , at least one hydrogen may be replaced by -F or -CH ₃ ; s, t and u are each independently an integer of 0 to 2, the sum of which is 1 to 5; when s, t or u is 2, the two bonding groups in the respective parentheses may be the same or different, and the two rings may be the same or different. R ²⁶ is hydrogen, -F, -OH, alkyl having 1 to 30 carbon atoms, fluorine-substituted alkyl having 1 to 30 carbon atoms, alkoxy having 1 to 30 carbon atoms, -CN, -OCH ₂ F, -OCHF ₂ , or -OCF ₃ , and at least one -CH ₂ - in the alkyl having 1 to 30 carbon atoms may be substituted with a divalent group represented by the following formula (DI-31-b).

In formula (DI-31-b), R ²⁷ and R ²⁸ each independently represent alkyl having 1 to 3 carbon atoms, and v represents an integer of 1 to 6. Preferred examples of R ²⁶ include alkyl having 1 to 30 carbon atoms and alkoxy having 1 to 30 carbon atoms.

式（ＤＩ－３２）および式（ＤＩ－３３）において、Ｇ^３０は独立して単結合、－ＣＯ－または－ＣＨ_２－であり、Ｒ^２９は独立して水素または－ＣＨ_３であり、Ｒ^３０は水素、炭素数１～２０のアルキル、または炭素数２～２０のアルケニルである。式（ＤＩ－３３）におけるベンゼン環の少なくとも１つの水素は、炭素数１～２０のアルキルまたはフェニルで置換されてもよい。そして、環を構成するいずれかの炭素に結合位置が固定されていない基は、その環における結合位置が任意であることを示す。式（ＤＩ－３２）における２つの基「－フェニレン－Ｇ^３０－Ｏ－」の一方はステロイド核の３位に結合し、もう一方はステロイド核の６位に結合していることが好ましい。式（ＤＩ－３３）における２つの基「－フェニレン－Ｇ^３０－Ｏ－」のベンゼン環への結合位置は、ステロイド核の結合位置に対して、それぞれメタ位またはパラ位であることが好ましい。式（ＤＩ－３２）および式（ＤＩ－３３）において、ベンゼン環に結合する－ＮＨ_２はその環における結合位置が任意であることを示す。

In formula (DI-32) and formula (DI-33), G ³⁰ is independently a single bond, -CO- or -CH ₂ -, R ²⁹ is independently hydrogen or -CH ₃ , and R ³⁰ is hydrogen, an alkyl having 1 to 20 carbon atoms, or an alkenyl having 2 to 20 carbon atoms. At least one hydrogen atom in the benzene ring in formula (DI-33) may be substituted with an alkyl having 1 to 20 carbon atoms or phenyl. A group that is not fixedly bonded to any carbon constituting the ring indicates that the bond position in the ring is arbitrary. One of the two groups "-phenylene-G ³⁰ -O-" in formula (DI-32) is preferably bonded to the 3-position of the steroid nucleus, and the other is preferably bonded to the 6-position of the steroid nucleus. The bond positions of the two groups "-phenylene-G ³⁰ -O-" in formula (DI-33) to the benzene ring are preferably meta-position or para-position with respect to the bond position of the steroid nucleus. In formulae (DI-32) and (DI-33), --NH ₂ bonded to a benzene ring indicates that the bonding position on the ring is arbitrary.

式（ＤＩ－３４）および式（ＤＩ－３５）において、Ｇ^３１は独立して－Ｏ－または炭素数１～６のアルキレンであり、Ｇ^３２は単結合または炭素数１～３のアルキレンである。Ｒ^３１は水素または炭素数１～２０のアルキルであり、このアルキルの少なくとも１つの－ＣＨ_２－は、－Ｏ－、－ＣＨ＝ＣＨ－または－Ｃ≡Ｃ－で置き換えられてもよい。Ｒ^３２は炭素数６～２２のアルキルであり、Ｒ^３３は水素または炭素数１～２２のアルキルである。環Ｂ^２５は１，４－フェニレンまたは１，４－シクロヘキシレンであり、ｒは０または１である。そしてベンゼン環に結合する－ＮＨ_２はその環における結合位置が任意であることを示すが、独立してＧ^３１の結合位置に対してメタ位またはパラ位であることが好ましい。

In formula (DI-34) and formula (DI-35), G ³¹ is independently -O- or alkylene having 1 to 6 carbon atoms, and G ³² is a single bond or alkylene having 1 to 3 carbon atoms. R ³¹ is hydrogen or alkyl having 1 to 20 carbon atoms, and at least one -CH ₂ - of this alkyl may be replaced by -O-, -CH=CH- or -C≡C-. R ³² is alkyl having 6 to 22 carbon atoms, and R ³³ is hydrogen or alkyl having 1 to 22 carbon atoms. Ring B ²⁵ is 1,4-phenylene or 1,4-cyclohexylene, and r is 0 or 1. And -NH ₂ bonded to the benzene ring indicates that the bonding position in the ring is arbitrary, but it is preferably independently meta-position or para-position with respect to the bonding position of G ³¹ .

Examples of the compound represented by formula (DI-31) are shown in the following formulas (DI-31-1) to (DI-31-55).

In formulae (DI-31-1) to (DI-31-11), R ³⁴ is independently alkyl having 1 to 30 carbon atoms or alkoxy having 1 to 30 carbon atoms, preferably alkyl having 5 to 25 carbon atoms or alkoxy having 5 to 25 carbon atoms. R ³⁵ is independently alkyl having 1 to 30 carbon atoms or alkoxy having 1 to 30 carbon atoms, preferably alkyl having 3 to 25 carbon atoms or alkoxy having 3 to 25 carbon atoms.

In formulae (DI-31-12) to (DI-31-17), R ³⁶ is independently an alkyl group having 4 to 30 carbon atoms, preferably an alkyl group having 6 to 25 carbon atoms. R ³⁷ is independently an alkyl group having 6 to 30 carbon atoms, preferably an alkyl group having 8 to 25 carbon atoms.

In formulae (DI-31-18) to (DI-31-43), R ³⁸ is independently alkyl having 1 to 20 carbon atoms or alkoxy having 1 to 20 carbon atoms, preferably alkyl having 3 to 20 carbon atoms or alkoxy having 3 to 20 carbon atoms. R ³⁹ is independently hydrogen, -F, alkyl having 1 to 30 carbon atoms, alkoxy having 1 to 30 carbon atoms, -CN, -OCH ₂ F, -OCHF ₂ or -OCF ₃ , preferably alkyl having 3 to 25 carbon atoms or alkoxy having 3 to 25 carbon atoms. And G ³³ is alkylene having 1 to 20 carbon atoms.

Examples of the compound represented by formula (DI-32) are shown in the following formulas (DI-32-1) to (DI-32-4).

Examples of the compound represented by formula (DI-33) are shown in the following formulas (DI-33-1) to (DI-33-8).

式（ＤＩ－３４－１）～式（ＤＩ－３４－１２）において、Ｒ^４０はそれぞれ独立して水素または炭素数１～２０のアルキル、好ましくは水素または炭素数１～１０のアルキルであり、そしてＲ^４１はそれぞれ独立して水素または炭素数１～１２のアルキルである。 Examples of the compound represented by formula (DI-34) are shown in the following formulas (DI-34-1) to (DI-34-12).

In formulae (DI-34-1) to (DI-34-12), each R ⁴⁰ is independently hydrogen or alkyl having 1 to 20 carbon atoms, preferably hydrogen or alkyl having 1 to 10 carbon atoms, and each R ⁴¹ is independently hydrogen or alkyl having 1 to 12 carbon atoms.

式（ＤＩ－３５－１）～式（ＤＩ－３５－３）において、Ｒ^３７はそれぞれ独立して炭素数６～３０のアルキルであり、Ｒ^４１はそれぞれ独立して水素または炭素数１～１２のアルキルである。 Examples of the compound represented by formula (DI-35) are shown in the following formulas (DI-35-1) to (DI-35-3).

In formulae (DI-35-1) to (DI-35-3), R ³⁷ is independently an alkyl group having 6 to 30 carbon atoms, and R ⁴¹ is independently a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.

式（ＤＩ－３６－１）～式（ＤＩ－３６－８）において、Ｒ^４２はそれぞれ独立して炭素数３～３０のアルキルである。 The compounds represented by formulae (DI-36-1) to (DI-36-8) are shown below.

In formulae (DI-36-1) to (DI-36-8), R ⁴² is each independently an alkyl group having 3 to 30 carbon atoms.

Among the above diamines, preferred materials for improving the properties of the liquid crystal alignment film described below will be described. When emphasis is placed on improving the liquid crystal alignment, it is preferred to use a compound represented by formula (DI-1-3), formula (DI-5-1), formula (DI-5-5), formula (DI-5-9), formula (DI-5-12), formula (DI-5-13), formula (DI-5-29), formula (DI-6-7), formula (DI-7-3), or formula (DI-11-2). In formula (DI-5-1), m is preferably 2 to 8, and more preferably m is 4 to 8. In formula (DI-5-12), m is preferably 2 to 6, and more preferably m is 5. In formula (DI-5-13), m is preferably 1 or 2, and more preferably m is 1.

When emphasis is placed on improving the transmittance, it is preferable to use a diamine represented by formula (DI-1-3), formula (DI-2-1), formula (DI-5-1), formula (DI-5-5), formula (DI-5-24), or formula (DI-7-3), and more preferably a compound represented by formula (DI-2-1). In formula (DI-5-1), m is preferably 2 to 8, and more preferably m is 8. In formula (DI-7-3), m is preferably 2 or 3, n is preferably 1 or 2, and more preferably m is 3, n is 1.

When emphasis is placed on improving the VHR of the liquid crystal display element, it is preferable to use a compound represented by formula (DI-2-1), formula (DI-4-1), formula (DI-4-2), formula (DI-4-10), formula (DI-4-15), formula (DI-4-22), formula (DI-5-1), formula (DI-5-28), formula (DI-5-30), or formula (DI-13-1), and more preferable is a diamine represented by formula (DI-2-1), formula (DI-5-1), or formula (DI-13-1). In formula (DI-5-1), m=1 is preferable. In formula (DI-5-30), k=2 is preferable.

One effective method for preventing image sticking is to improve the relaxation speed of the residual charge (residual DC) in the liquid crystal alignment film by reducing the volume resistance of the liquid crystal alignment film. When this purpose is important, it is preferable to use a compound represented by formula (DI-4-1), formula (DI-4-2), formula (DI-4-10), formula (DI-4-15), formula (DI-5-1), formula (DI-5-12), formula (DI-5-13), formula (DI-5-28), formula (DI-4-20), formula (DI-4-21), formula (DI-7-12), or formula (DI-16-1), and more preferable is a compound represented by formula (DI-4-1), formula (DI-5-1), or formula (DI-5-13). In formula (DI-5-1), m=2 to 8 is preferable, and m=4 to 8 is more preferable. In formula (DI-5-12), m is preferably 2 to 6, and more preferably m is 5. In formula (DI-5-13), m is preferably 1 or 2, and more preferably m is 1. In formula (DI-7-12), m is preferably 3 or 4, and more preferably m is 4.

In the raw material composition used as the raw material for the polymer of the present invention, a part of the diamines may be replaced with at least one selected from the group consisting of monoamines and monohydrazides. The ratio of at least one selected from the group consisting of monoamines and monohydrazides to the diamines is preferably in the range of 40 mol% or less. Such a replacement can cause the termination of the polymerization reaction when producing polyamic acid, and can suppress further progress of the polymerization reaction. For this reason, such a replacement can easily control the molecular weight of the resulting polymer (polyamic acid or its derivative), and can improve the coating properties of the liquid crystal alignment agent, for example, without impairing the effects of the present invention. The diamines that may be replaced with monoamines or monohydrazides may be one type or two or more types, as long as the effects of the present invention are not impaired. Examples of the monoamine include aniline, 4-hydroxyaniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-undecylamine, n-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, n-eicosylamine, paraaminophenyltrimethoxysilane, and 3-aminopropyltriethoxysilane.

When the polymer of the present invention is a polyamic acid or a derivative thereof, the raw material composition may further contain a monoisocyanate compound as a monomer. By including a monoisocyanate compound in the monomer, the terminal of the resulting polyamic acid or its derivative is modified, and the molecular weight is adjusted. By using this terminal-modified polyamic acid or its derivative, for example, it is possible to improve the coating properties of the liquid crystal alignment agent without impairing the effect of the present invention. From the above viewpoint, it is preferable that the content of the monoisocyanate compound in the monomer is 1 to 10 mol% based on the total amount of the diamine and tetracarboxylic dianhydride in the monomer. Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.

The liquid crystal alignment agent of the present invention may be composed of one type of polymer of the present invention, or may be a mixture of the polymer of the present invention and a polymer other than the polymer of the present invention. In this specification, a liquid crystal alignment agent composed of one type of polymer may be referred to as a single-layer type liquid crystal alignment agent. A liquid crystal alignment agent that is a mixture of two or more types of the above polymers may be referred to as a blend type liquid crystal alignment agent. A blend type liquid crystal alignment agent is used particularly when VHR reliability and other electrical characteristics are important.

As the polymer other than the polymer of the present invention used in the blend type liquid crystal alignment agent, one or more of polyamic acid and polyamic acid derivatives are preferable. As for the polymer other than the polymer of the present invention, the above description of the polymer of the present invention can be referred to for polyamic acid and polyamic acid derivatives, except that the raw material composition does not contain the compound represented by formula (1).

When using a two-component polymer, for example, one polymer is selected that has excellent performance in aligning liquid crystals, and the other is selected that has excellent performance in improving the electrical properties of liquid crystal display elements. This is suitable for obtaining an alignment agent that has a good balance between liquid crystal alignment properties and electrical properties.

In this case, by controlling the structure and molecular weight of each polymer, the liquid crystal alignment agent in which these polymers are dissolved in a solvent is applied to a substrate as described below, and in the process of forming a thin film by pre-drying, the polymer with excellent performance in aligning liquid crystals can be segregated to the upper layer of the thin film, and the polymer with excellent performance in improving the electrical properties of the liquid crystal display element can be segregated to the lower layer of the thin film. This can be achieved by applying the phenomenon in which a polymer with a small surface energy is separated into the upper layer and a polymer with a large surface energy is separated into the lower layer in a mixed polymer. Such layer separation can be confirmed by checking that the surface energy of the formed liquid crystal alignment film is the same as or close to the surface energy of a film formed by a liquid crystal alignment agent containing only the polymer intended to be segregated to the upper layer.

When using liquid crystal alignment agents consisting of a mixture of polymers, layer separation can be achieved by using polyimide as the polymer to be segregated to the upper layer.

The compound represented by formula (1) may be used as a raw material for the polymer that segregates in the upper layer of the thin film, or may be used as a raw material for the polymer that segregates in the lower layer of the thin film, or may be used as a raw material for both polymers, but is more preferably used as a raw material for the polymer that segregates in the upper layer of the thin film.

The compound having a photoreactive structure may be used as a raw material for the polymer that segregates in the upper layer of the thin film, or may be used as a raw material for the polymer that segregates in the lower layer of the thin film, or may be used as a raw material for both polymers, but it is more preferable to use it as a raw material for the polymer that segregates in the upper layer of the thin film.

The tetracarboxylic acid dianhydride other than the compound represented by formula (1) used to synthesize the polyamic acid or its derivative segregated in the upper layer of the thin film and the polyamic acid or its derivative segregated in the lower layer of the thin film can be selected without limitation from the known tetracarboxylic acid dianhydrides exemplified above.

The tetracarboxylic dianhydride used to synthesize the polyamic acid or its derivative that segregates in the upper layer of the thin film is preferably a compound represented by formula (AN-1-1), (AN-1-2), (AN-2-1), (AN-3-1), (AN-4-5), or (AN-4-17), more preferably formula (AN-2-1) or (AN-4-17). In formula (AN-4-17), m is preferably 4 to 8.

As the tetracarboxylic dianhydride used to synthesize the polyamic acid or its derivative that segregates in the lower layer of the thin film, a compound represented by formula (AN-1-1), formula (AN-1-13), formula (AN-2-1), formula (AN-3-2), or formula (AN-4-21) is preferred, and formula (AN-1-1), formula (AN-2-1), or formula (AN-3-2) is more preferred.

The tetracarboxylic dianhydride used to synthesize the polyamic acid or its derivative that segregates in the lower layer of the thin film preferably contains 10 mol % or more, and more preferably 30 mol % or more, of aromatic tetracarboxylic dianhydride in the total amount of tetracarboxylic dianhydride.

The diamines used to synthesize the polyamic acid or its derivative that segregates in the upper layer of the thin film and the polyamic acid or its derivative that segregates in the lower layer of the thin film can be selected from the known diamines exemplified above without any limitations.

As the diamines used to synthesize the polyamic acid or its derivatives that segregate in the upper layer of the thin film, it is preferable to use a compound represented by formula (DI-4-13), formula (DI-4-15), formula (DI-5-1), formula (DI-7-3), or formula (DI-13-1). Of these, it is more preferable to use a compound represented by formula (DI-4-13), formula (DI-4-15), formula (DI-5-1), or formula (DI-13-1). In formula (DI-5-1), m=4 to 8 is preferable. In formula (DI-7-3), m=3, n=1 is preferable.

As the diamines used to synthesize the polyamic acid or its derivatives that segregate in the lower layer of the thin film, compounds represented by formula (DI-4-1), formula (DI-4-2), formula (DI-4-10), formula (DI-4-18), formula (DI-4-19), formula (DI-5-1), formula (DI-5-9), formula (DI-5-28), formula (DI-5-30), formula (DI-13-1), or formula (DIH-1-2) are preferred. In formula (DI-5-1), compounds in which m=1 or 2 are preferred, and in formula (DI-5-30), compounds in which k=2 are preferred. Among them, compounds represented by formula (DI-4-1), formula (DI-4-18), formula (DI-4-19), formula (DI-5-9), formula (DI-13-1), or formula (DIH-1-2) are more preferred.

The diamines used to synthesize the polyamic acid or its derivatives that segregate in the lower layer of the thin film preferably contain at least one selected from the group consisting of aromatic diamines and aromatic dihydrazides in an amount of 30 mol % or more, and more preferably 50 mol % or more, based on the total amount of diamines.

The ratio of polyamic acid or its derivative segregated in the upper layer of the thin film to the total amount of polyamic acid or its derivative segregated in the upper layer of the thin film and polyamic acid or its derivative segregated in the lower layer of the thin film is preferably 5% by weight to 60% by weight, and more preferably 20% by weight to 50% by weight.

The polyamic acid or its derivative of the present invention may be a block polymer containing a first polymer chain and a second polymer chain having a structure different from that of the first polymer chain. The block polymer may further contain another polymer chain having a structure different from that of the first polymer chain and the second polymer chain. For example, a block polymer of polyamic acid can be formed by mixing a solution of a specific polyamic acid (PAA1) represented by formula (PAA) with a solution of a polyamic acid (PAA1) and a polyamic acid (PAA2) having a different combination of ^X1 and ^X2 , and heating the mixture. The block polymer of polyamic acid thus formed contains a block represented by (PAA1) _n1 and a block represented by (PAA2) _n2 . _n1 and n2 in (PAA1)n1 and (PAA2) _n2 are each independently an integer of 1 or more, and preferably each independently an integer of 2 or more. In the block polymer, the polymer chains using the compounds represented by formula (1) and formula (2) or formula (3) in the raw material composition may be any one, two or more, or all of the polymer chains.

Here, the polyamic acid block polymer may be synthesized by mixing two or more kinds of polyamic acids that are produced separately and then heating them. Alternatively, two or more kinds of polyamic acids may be synthesized in the same reaction vessel and then heated, such as by synthesizing the first kind of polyamic acid and then adding the raw material for the second kind of polyamic acid to the same reaction vessel.

When a block polymer is produced, in the raw material composition used as the raw material for the polymer of the present invention, the compound represented by formula (1) is preferably 10 mol % or more, more preferably 20 mol % or more, based on the total amount of the acid dianhydrides used as raw materials. The compound represented by formula (2) or formula (3) is preferably 10 mol % or more, more preferably 20 mol % or more, based on the total amount of the diamines used as raw materials.

The liquid crystal aligning agent of the present invention may further contain a solvent from the viewpoint of adjusting the coatability of the liquid crystal aligning agent and the concentration of the polyamic acid or its derivative. The solvent can be applied without any particular restrictions as long as it has the ability to dissolve polymer components. The solvent includes a wide range of solvents that are commonly used in the manufacturing process and applications of polymer components such as polyamic acid and soluble polyimide, and can be appropriately selected depending on the purpose of use. The solvent may be one type or a mixed solvent of two or more types.

Solvents include those that are compatible with the polyamic acid or its derivatives, and other solvents that are intended to improve coating properties.

Examples of aprotic polar organic solvents that are compatible with polyamic acid or its derivatives include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylimidazolidinone, N-methylcaprolactam, N-methylpropionamide, N,N-dimethylacetamide, dimethylsulfoxide, N,N-dimethylformamide, N,N-diethylformamide, diethylacetamide, N,N-dimethylisobutyramide, γ-butyrolactone, and γ-valerolactone. Among these, N-methyl-2-pyrrolidone, dimethylimidazolidinone, γ-butyrolactone, and γ-valerolactone are preferred.

Examples of other solvents for improving coating properties include ethylene glycol monoalkyl ethers such as ethylene glycol monobutyl ether and ethylene glycol monotertiary butyl ether, diethylene glycol monoalkyl ethers such as diethylene glycol monoethyl ether, and diethylene glycol dialkyl ethers such as diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, and diethylene glycol butyl methyl ether. Other examples include propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether and 1-butoxy-2-propanol, dipropylene glycol monoalkyl ethers such as dipropylene glycol monomethyl ether, triethylene glycol monoalkyl ethers, butyl cellosolve acetate, phenyl acetate, and ester compounds such as these acetates. Other examples include dialkyl malonates such as diethyl malonate, alkyl lactates, diisobutyl ketone, diacetone alcohol, 3-methyl-3-methoxybutanol, 4-methyl-2-pentanol, diisobutyl carbinol, tetralin, and isophorone.

Among these, diisobutyl ketone, 4-methyl-2-pentanol, diisobutyl carbinol, ethylene glycol monobutyl ether, ethylene glycol monotertiary butyl ether, diethylene glycol monoethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, diethylene glycol butyl methyl ether, 1-butoxy-2-propanol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, or butyl cellosolve acetate are preferred.

The solids concentration in the liquid crystal alignment agent of the present invention is not particularly limited, and an optimal value may be selected according to the various coating methods described below. In general, to prevent unevenness and pinholes during coating, the solids concentration is preferably 0.1 to 30% by weight, more preferably 1 to 10% by weight, based on the weight of the varnish.

The preferred range of the viscosity of the liquid crystal alignment agent of the present invention varies depending on the application method, the concentration of the polyamic acid or its derivative, the type of polyamic acid or its derivative used, and the type and ratio of the solvent. For example, in the case of application by a printer, the viscosity is 5 to 100 mPa·s (more preferably 10 to 80 mPa·s). If the viscosity is 5 mPa·s or more, a sufficient film thickness is easily obtained, and if the viscosity is 100 mPa·s or less, printing unevenness is easily suppressed. In the case of application by spin coating, the viscosity is suitable for 5 to 200 mPa·s (more preferably 10 to 100 mPa·s). In the case of application using an inkjet coating device, the viscosity is suitable for 5 to 50 mPa·s (more preferably 5 to 20 mPa·s). The viscosity of the liquid crystal alignment agent is measured by a rotational viscosity measurement method, for example, using a rotational viscometer (TVE-20L type viscometer manufactured by Toki Sangyo Co., Ltd.) (measurement temperature: 25°C).

The liquid crystal alignment agent of the present invention may further contain various additives. Various additives can be selected and used according to the respective purposes in order to improve various properties of the alignment film. Examples are shown below.

<Alkenyl-substituted nadimide compound>
For example, the liquid crystal alignment agent of the present invention may further contain an alkenyl-substituted nadimide compound for the purpose of stabilizing the electrical properties of the liquid crystal display element for a long period of time. The alkenyl-substituted nadimide compound may be used alone or in combination of two or more. For the above purpose, the content of the alkenyl-substituted nadimide compound is preferably 1 to 50% by weight, more preferably 1 to 30% by weight, and even more preferably 1 to 20% by weight, based on the polyamic acid or its derivative. The alkenyl-substituted nadimide compound is preferably a compound that can be dissolved in a solvent that dissolves the polyamic acid or its derivative used in the present invention. Preferred alkenyl-substituted nadimide compounds include the alkenyl-substituted nadimide compounds disclosed in JP-A-2008-096979, JP-A-2009-109987, and JP-A-2013-242526. Particularly preferred alkenyl-substituted nadimide compounds include bis{4-(arylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide)phenyl}methane, N,N'-m-xylylene-bis(arylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide), or N,N'-hexamethylene-bis(arylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide).

<Compound Having Radically Polymerizable Unsaturated Double Bond>
For example, the liquid crystal aligning agent of the present invention may further contain a compound having a radical polymerizable unsaturated double bond for the purpose of stabilizing the electrical characteristics of the liquid crystal display element for a long period of time. The compound having a radical polymerizable unsaturated double bond may be one type of compound, or may be two or more types of compounds. The compound having a radical polymerizable unsaturated double bond does not include an alkenyl-substituted nadiimide compound. Preferred compounds having a radical polymerizable unsaturated double bond include N,N'-methylenebisacrylamide, N,N'-dihydroxyethylene-bisacrylamide, ethylenebisacrylate, 4,4'-methylenebis(N,N-dihydroxyethyleneacrylateaniline), triallyl cyanurate, and other compounds having a radical polymerizable unsaturated double bond disclosed in JP 2009-109987 A, JP 2013-242526 A, WO 2014/119682 A, and WO 2015/152014 A. For the above-mentioned purposes, the content of the compound having a radically polymerizable unsaturated double bond is preferably 1 to 50% by weight, more preferably 1 to 30% by weight, based on the polyamic acid or its derivative.

<Oxazine Compound>
For example, the liquid crystal aligning agent of the present invention may further contain an oxazine compound for the purpose of stabilizing the electrical characteristics of a liquid crystal display element for a long period of time. The oxazine compound may be one type of compound or two or more types of compounds. For the above purpose, the content of the oxazine compound is preferably 0.1 to 50% by weight, more preferably 1 to 40% by weight, and even more preferably 1 to 20% by weight, based on the polyamic acid or its derivative.

The oxazine compound is preferably an oxazine compound that is soluble in a solvent that dissolves polyamic acid or a derivative thereof and has ring-opening polymerizability. Preferred oxazine compounds include the oxazine compounds represented by formula (OX-3-1), formula (OX-3-9), and formula (OX-3-10), as well as the oxazine compounds disclosed in JP-A-2007-286597 and JP-A-2013-242526.

<Oxazoline Compound>
For example, the liquid crystal aligning agent of the present invention may further contain an oxazoline compound for the purpose of stabilizing the electrical characteristics of a liquid crystal display element for a long period of time. The oxazoline compound is a compound having an oxazoline structure. The oxazoline compound may be one type of compound or two or more types of compounds. For the above purpose, the content of the oxazoline compound is preferably 0.1 to 50% by weight, more preferably 1 to 40% by weight, and even more preferably 1 to 20% by weight, based on the polyamic acid or its derivative. Preferred oxazoline compounds include the oxazoline compounds disclosed in JP-A-2010-054872 and JP-A-2013-242526. More preferably, 1,3-bis(4,5-dihydro-2-oxazolyl)benzene is used.

<Epoxy Compound>
For example, the liquid crystal aligning agent of the present invention may further contain an epoxy compound for the purpose of stabilizing the electrical characteristics of a liquid crystal display element for a long period of time, improving the hardness of the film, or improving the adhesion to a sealant. The epoxy compound may be one type of compound or two or more types of compounds. For the above purposes, the content of the epoxy compound is preferably 0.1 to 50% by weight, more preferably 1 to 20% by weight, and even more preferably 1 to 10% by weight, based on the polyamic acid or its derivative.

As the epoxy compound, various compounds having one or more epoxy rings in the molecule can be used.
For the purpose of improving the hardness of the film or the adhesion to the sealant, a compound having two or more epoxy rings in the molecule is preferred, and a compound having three or four epoxy rings is more preferred.

Examples of epoxy compounds include the epoxy compounds disclosed in JP 2009-175715 A, JP 2013-242526 A, JP 2016-170409 A, and WO 2017/217413. Preferred epoxy compounds include N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, (3,3',4,4'-diepoxy)bicyclohexyl, 1,4-butanediol glycidyl ether, tris(2,3-epoxypropyl) isocyanurate, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, or N,N,N',N'-tetraglycidyl-m-xylylenediamine. More preferred are 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane. In addition to the above, oligomers or polymers having epoxy rings can also be added. The oligomers and polymers having epoxy rings can be those disclosed in JP 2013-242526 A.

<Silane Compound>
For example, the liquid crystal aligning agent of the present invention may further contain a silane compound for the purpose of improving adhesion to a substrate and a sealant. For the above purpose, the content of the silane compound is preferably 0.1 to 30% by weight, more preferably 0.5 to 20% by weight, and even more preferably 0.5 to 10% by weight, based on the polyamic acid or its derivative.

As the silane compound, the silane coupling agents disclosed in JP 2013-242526 A, JP 2015-212807 A, JP 2018-173545 A, and WO 2018/181566 A can be used. Preferred silane coupling agents include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, paraaminophenyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-isocyanatopropyltriethoxysilane, and 3-ureidopropyltriethoxysilane.

In addition to the additives described above, a compound having a cyclocarbonate group, a hydroxyalkylamide moiety, or a hydroxyl group may be added for the purpose of increasing the strength of the alignment film or stabilizing the electrical properties of the liquid crystal display element for a long period of time. Specific examples of the compound include those disclosed in JP 2016-118753 A and WO 2017/110976 A. Preferred examples of the compound include the following formulae (HD-1) to (HD-4). These compounds are preferably 0.5 to 50% by weight, more preferably 1 to 30% by weight, and even more preferably 1 to 10% by weight, based on the polyamic acid or its derivative.

When improved antistatic properties are required, antistatic agents can be used, and when imidization is to proceed at low temperatures, imidization catalysts can be used. Examples of imidization catalysts include the imidization catalysts disclosed in JP 2013-242526 A.

<Liquid crystal alignment film>
Next, the liquid crystal alignment film of the present invention will be described. The liquid crystal alignment film of the present invention is formed using the liquid crystal alignment agent of the present invention. When the liquid crystal alignment agent of the present invention is used to form a liquid crystal alignment film, heating and baking causes an imidization reaction, and a polyimide-based liquid crystal alignment film can be formed. The liquid crystal alignment agent of the present invention is suitable as a liquid crystal alignment agent for photo-alignment, and a photo-alignment method can be applied to the alignment treatment in the process of forming the liquid crystal alignment film.

The following describes a method for forming a liquid crystal alignment film using the liquid crystal alignment agent of the present invention.

The liquid crystal alignment film of the present invention can be obtained by a normal method for producing a liquid crystal alignment film from a liquid crystal alignment agent for photo-alignment. The liquid crystal alignment film of the present invention can be obtained, for example, through a process of forming a coating film of the liquid crystal alignment agent of the present invention, a process of heating and drying the coating film to form a film of the liquid crystal alignment agent, a process of irradiating the film of the liquid crystal alignment agent with light to impart anisotropy, and a process of heating and baking the film of the liquid crystal alignment agent to which anisotropy has been imparted.

The coating film can be formed by applying the liquid crystal alignment agent of the present invention to a substrate in a liquid crystal display element in the same manner as in the preparation of a normal liquid crystal alignment film. The substrate may be made of glass, silicon nitride, acrylic, polycarbonate, polyimide, or the like, which may be provided with electrodes such as ITO (indium tin oxide), IZO (In ₂ O ₃ -ZnO), or IGZO (In-Ga-ZnO ₄ ) electrodes, or color filters, or the like.

Methods commonly known for applying a liquid crystal alignment agent to a substrate include the spinner method, printing method, dipping method, dropping method, inkjet method, etc. These methods can also be applied to the present invention.

The commonly known heat drying process involves heating in an oven or infrared furnace, or on a hot plate. The heat drying process is preferably carried out at a temperature within a range in which the solvent can evaporate, and more preferably at a temperature relatively low compared to the temperature in the heat baking process. Specifically, the heat drying temperature is preferably in the range of 30°C to 150°C, and more preferably in the range of 50°C to 120°C.

The heating and baking process can be carried out under conditions necessary for the polyamic acid or its derivatives to undergo an imidization reaction. Commonly known methods for baking a coating film include a method of heating in an oven or infrared furnace, and a method of heating on a hot plate. These methods can also be applied to the present invention. In general, it is preferable to perform the baking at a temperature of about 90 to 300°C for 1 minute to 3 hours, more preferably 120 to 280°C, and even more preferably 150 to 250°C.

When emphasis is placed on improving the anisotropy of the film or the afterimage characteristics when the liquid crystal display element is produced, it is preferable to raise the temperature gradually in the heating process. For example, the temperature can be raised stepwise and the film can be heated and baked multiple times at different temperatures, or the temperature can be changed from low to high. Also, both heating methods can be used in combination.

When heating and firing multiple times at different temperatures, multiple heating devices set to different temperatures may be used, or one heating device may be used and the temperature may be changed sequentially to different temperatures.

When firing multiple times at different temperatures, it is preferable to fire the product at 90 to 180°C for the first firing, and 185 to 300°C for the final firing. For example, it is preferable to fire the product at 110°C and then at 220°C, fire the product at 110°C and then at 230°C, fire the product at 130°C and then at 220°C, fire the product at 150°C and then at 200°C, fire the product at 150°C and then at 220°C, fire the product at 150°C and then at 230°C, or fire the product at 170°C and then at 200°C. It is also preferable to fire the product in more stages while gradually increasing the temperature. When firing the product in two or more stages with different heating temperatures, it is preferable that the heating time for each heating step is 5 to 30 minutes.

When firing is performed by changing the temperature from a low temperature to a high temperature, the initial temperature is preferably 90 to 180°C. The final temperature is preferably 185 to 300°C, more preferably 190 to 230°C. The heating time is preferably 5 to 60 minutes, more preferably 20 to 60 minutes. The temperature rise speed can be, for example, 0.5°C/min to 40°C/min. The temperature rise speed during the temperature rise does not have to be constant.

In the method for forming a liquid crystal alignment film of the present invention, a known photoalignment method can be suitably used as a means for imparting anisotropy to the thin film in order to align the liquid crystal in one direction relative to the horizontal and/or vertical directions.

The method for forming the liquid crystal alignment film of the present invention using the photo-alignment method will be described in detail. The liquid crystal alignment film of the present invention using the photo-alignment method can be formed by heating and drying the coating film, irradiating the thin film with light to impart anisotropy to the thin film, and then heating and baking the film. Alternatively, the coating film can be formed by heating and drying the coating film, heating and baking it, and then irradiating the thin film with light.

Furthermore, in order to increase the liquid crystal alignment ability of the liquid crystal alignment film, the coating film can be irradiated with light while being heated. The light irradiation can be performed in the process of heating and drying the coating film or in the process of heating and baking, or between the heating and baking processes. The heating temperature when irradiating light in the process of heating and drying the coating film or in the process of heating and baking can be determined by referring to the description of the heating and baking process above. When irradiating light between the heating and drying process and the heating and baking process, the heating temperature is preferably in the range of 30°C to 150°C, and more preferably in the range of 50°C to 110°C.

The light used in the light irradiation step in the photo-alignment method can be, for example, ultraviolet light or visible light containing light with a wavelength of 150 to 800 nm. There are no particular limitations on the type of light, so long as it is capable of imparting liquid crystal alignment ability to the thin film. However, if it is desired to exert a strong alignment control force on the liquid crystal, polarized light is preferred, and linearly polarized light is even more preferred.

The amount of polarized light in the light irradiation step is preferably 0.05 to 10 J/ ^cm2 , more preferably 0.1 to 5 J/ ^cm2 . The wavelength of the polarized light is preferably changed depending on the compound having a photoreactive structure. When a compound represented by formula (2) is used, the wavelength of the polarized light is preferably 200 to 400 nm, more preferably 300 to 400 nm. When a compound represented by formula (3) is used, the wavelength of the polarized light is preferably 150 to 350 nm, more preferably 200 to 300 nm. The irradiation angle of the polarized light to the film surface is not particularly limited, but when it is desired to express a strong alignment control force for the liquid crystal, it is preferable that the irradiation angle is as perpendicular as possible to the film surface from the viewpoint of shortening the alignment treatment time. In addition, the liquid crystal alignment film of the present invention can align the liquid crystal in a direction perpendicular to the polarization direction of the linearly polarized light by irradiating it with linearly polarized light.

Light sources used in the light irradiation process can include, without limitation, ultra-high pressure mercury lamps, high pressure mercury lamps, low pressure mercury lamps, deep UV lamps, halogen lamps, metal halide lamps, high power metal halide lamps, xenon lamps, mercury xenon lamps, excimer lamps, KrF excimer lasers, fluorescent lamps, LED lamps, sodium lamps, microwave excited electrodeless lamps, etc.

The liquid crystal alignment film of the present invention can be suitably obtained by a method that further includes steps other than those described above.

The liquid crystal alignment film of the present invention does not require a step of washing the film with a washing solution after baking or light irradiation, but a washing step can be provided for the convenience of other steps. Examples of washing methods using a washing solution include brushing, jet spray, steam washing, and ultrasonic washing. These methods may be performed alone or in combination. The washing solution may be, but is not limited to, pure water or various alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol, aromatic hydrocarbons such as benzene, toluene, and xylene, halogenated solvents such as methylene chloride, and ketones such as acetone and methyl ethyl ketone. Of course, these washing solutions are sufficiently purified and contain few impurities. Such washing methods can also be applied to the washing step in the formation of the liquid crystal alignment film of the present invention.

In order to enhance the liquid crystal alignment ability of the liquid crystal alignment film of the present invention, an annealing treatment using heat or light can be used before or after the heating and baking process, or before or after irradiation with polarized or unpolarized light. In the annealing treatment, the annealing temperature is 30 to 180°C, preferably 50 to 150°C, and the time is preferably 1 minute to 2 hours. The annealing light used in the annealing treatment may be a UV lamp, a fluorescent lamp, an LED lamp, or the like. The light irradiation dose is preferably 0.3 to 10 J/ ^cm2 .

The thickness of the liquid crystal alignment film of the present invention is not particularly limited, but is preferably 10 to 300 nm, and more preferably 30 to 150 nm. The thickness of the liquid crystal alignment film of the present invention can be measured using a known film thickness measuring device such as a step gauge or an ellipsometer.

The liquid crystal alignment film of the present invention is characterized by having a particularly large anisotropy of alignment. The magnitude of such anisotropy can be evaluated by a method using polarized IR as described in JP-A-2005-275364, etc. It can also be evaluated by a method using ellipsometry. More specifically, the retardation value of the liquid crystal alignment film can be measured by a spectroscopic ellipsometer. The retardation value of the film increases in proportion to the degree of orientation of the polymer main chain.

The liquid crystal alignment film of the present invention can be suitably used for controlling the alignment of liquid crystal compositions in liquid crystal display elements. In addition to the use of aligning liquid crystal compositions in liquid crystal display elements, it can be used for controlling the alignment of liquid crystal materials in all other liquid crystal elements, such as liquid crystal antennas, dimming windows, optical compensation materials, variable phase shifters, etc. In addition, since the liquid crystal alignment film of the present invention has a large anisotropy, it can be used alone as an optical compensation material.

<Liquid crystal display element>
The liquid crystal display element of the present invention is characterized by having the liquid crystal alignment film of the present invention, and can realize high display quality due to its good contrast.

The liquid crystal display element of the present invention will be described in detail. The present invention is a liquid crystal display element having a pair of substrates arranged opposite to each other, electrodes formed on one or both of the opposing surfaces of each of the pair of substrates, a liquid crystal alignment film formed on the opposing surfaces of each of the pair of substrates, a liquid crystal layer formed between the pair of substrates, a pair of polarizing films arranged to sandwich the opposing substrates, a backlight, and a driving device, in which the liquid crystal alignment film is composed of the liquid crystal alignment film of the present invention.

The electrode is not particularly limited as long as it is an electrode formed on one side of the substrate. Examples of such electrodes include ITO and a metal deposition film. The electrode may be formed on the entire surface of one side of the substrate, or may be formed in a desired shape, for example, patterned. Examples of the desired shape of the electrode include a comb-shaped or zigzag structure. The electrode may be formed on one of the pair of substrates, or on both substrates. The form of electrode formation differs depending on the type of liquid crystal display element. For example, in the case of an IPS type liquid crystal display element (horizontal electric field type liquid crystal display element), an electrode is arranged on one of the pair of substrates, and in the case of other liquid crystal display elements, an electrode is arranged on both of the pair of substrates. The liquid crystal alignment film is formed on the substrate or the electrode.

In the case of a homogeneously aligned liquid crystal display element (e.g., IPS, FFS, etc.), the structure includes at least, from the backlight side, a backlight, a first polarizing film, a first substrate, a first liquid crystal alignment film, a liquid crystal layer, a second substrate, and a second polarizing film, and the polarizing axis of the polarizing film is set so that the polarizing axis of the first polarizing film (direction of polarized light absorption) crosses (preferably perpendicular) with the polarizing axis of the second polarizing film. In this case, the polarizing axis of the first polarizing film can be set so that it is parallel to the liquid crystal alignment direction or perpendicular to the liquid crystal alignment direction. A liquid crystal display element in which the polarizing axis of the first polarizing film is set so that it is parallel to the liquid crystal alignment direction is called O-mode, and a liquid crystal display element in which it is set so that it is perpendicular to the liquid crystal alignment direction is called E-mode. The liquid crystal alignment film of the present invention can be applied to either O-mode or E-mode, and can be selected according to the purpose.

Many photoisomerization materials use compounds with dichroism. Therefore, if the polarization axis of the polarized light irradiated to impart anisotropy to the liquid crystal alignment agent is aligned parallel to the polarization axis of the polarized light from the polarizing film placed on the backlight side (when the liquid crystal alignment agent of the present invention is used, this is the O-mode arrangement), the transmittance of the liquid crystal alignment film in the light absorption wavelength range increases. This can further improve the transmittance of the liquid crystal display element.

The liquid crystal layer is formed by sandwiching a liquid crystal composition between the pair of substrates with the surfaces on which the liquid crystal alignment film is formed facing each other. When forming the liquid crystal layer, spacers such as fine particles or resin sheets that are interposed between the pair of substrates to form an appropriate gap can be used as necessary.

Known methods for forming liquid crystal layers are the vacuum injection method and the ODF (One Drop Fill) method.

In the vacuum injection method, a gap (cell gap) is provided so that the liquid crystal alignment film surfaces face each other, and a sealant is printed leaving an inlet for the liquid crystal, and then the substrates are bonded together. The cell gap defined by the substrate surface and the sealant is filled with liquid crystal using a vacuum pressure difference, and the inlet is then sealed to produce a liquid crystal display element.

In the ODF method, a sealant is printed on the outer periphery of the liquid crystal alignment film surface of one of a pair of substrates, liquid crystal is dropped into the area inside the sealant, and then the other substrate is attached so that the liquid crystal alignment film surface faces the other. The liquid crystal is then spread over the entire surface of the substrate, and then the entire surface of the substrate is irradiated with ultraviolet light to harden the sealant, thereby producing a liquid crystal display element.

In addition to UV-curing types, heat-curing types are also known as sealants used to bond substrates. The sealant can be printed, for example, by screen printing.

There are no particular limitations on the liquid crystal composition, and various liquid crystal compositions having positive or negative dielectric anisotropy can be used. Preferred liquid crystal compositions having positive dielectric anisotropy are described in Japanese Patent No. 3086228, Japanese Patent No. 2635435, JP-T-5-501735, JP-A-8-157826, JP-A-8-231960, JP-A-9-241644 (EP 885272 A1), JP-A-9-302346 (EP 806466 A2), JP-A-8-199168 (EP 722998 A1), and the like. ), liquid crystal compositions disclosed in JP-A-9-235552, JP-A-9-255956, JP-A-9-241643 (EP885271A1), JP-A-10-204016 (EP844229A1), JP-A-10-204436, JP-A-10-231482, JP-A-2000-087040, JP-A-2001-48822, etc. are included.

Preferred examples of the liquid crystal composition having the negative dielectric anisotropy are described in JP-A-57-114532, JP-A-2-4725, JP-A-4-224885, JP-A-8-40953, JP-A-8-104869, JP-A-10-168076, JP-A-10-168453, JP-A-10-236989, and JP-A-10-236989. Japanese Patent Application Publication No. 10-236990, Japanese Patent Application Publication No. 10-236992, Japanese Patent Application Publication No. 10-236993, Japanese Patent Application Publication No. 10-236994, Japanese Patent Application Publication No. 10-237000, Japanese Patent Application Publication No. 10-237004, Japanese Patent Application Publication No. 10-237024, Japanese Patent Application Publication No. 10-237035, Japanese Patent Application Publication No. 10-237075, Japanese Patent Application Publication No. 10-23707 6, JP-A-10-237448 (EP967261A1), JP-A-10-287874, JP-A-10-287875, JP-A-10-291945, JP-A-11-029581, JP-A-11-080049, JP-A-2000-256307, JP-A-2001-019965, JP-A-2001 Examples of the liquid crystal compositions include those disclosed in JP-A-072626, JP-A-2001-192657, JP-A-2010-037428, WO 2011/024666, WO 2010/072370, JP-T-2010-537010, JP-A-2012-077201, and JP-A-2009-084362.

There is no problem with adding one or more optically active compounds to a liquid crystal composition having a positive or negative dielectric anisotropy.

For example, the liquid crystal composition used in the liquid crystal display element of the present invention may further contain additives, for example, from the viewpoint of improving the alignment. Such additives include photopolymerizable monomers, optically active compounds, antioxidants, UV absorbers, dyes, defoamers, polymerization initiators, and polymerization inhibitors. Preferred photopolymerizable monomers, optically active compounds, antioxidants, UV absorbers, dyes, defoamers, polymerization initiators, and polymerization inhibitors include the compounds disclosed in International Publication No. WO 2015/146330 and the like.

A polymerizable compound can be mixed into the liquid crystal composition to adapt it to a liquid crystal display element in a PSA (polymer sustained alignment) mode. Preferred examples of the polymerizable compound include compounds having a polymerizable group, such as acrylates, methacrylates, vinyl compounds, vinyloxy compounds, propenyl ethers, epoxy compounds (oxiranes, oxetanes), and vinyl ketones. Preferred compounds include those disclosed in International Publication No. WO 2015/146330 and the like.

The present invention will be described below with reference to examples. The evaluation methods and compounds used in the examples are as follows.

Weight average molecular weight (Mw)
The weight average molecular weight of the polyamic acid was measured by GPC using a 2695 Separation Module-2414 Differential Refractometer (Waters Corporation) and calculated in terms of polystyrene. The obtained polyamic acid was diluted with a phosphoric acid-DMF mixed solution (phosphoric acid/DMF=0.6/100: weight ratio) so that the polyamic acid concentration was about 2 wt%. The column used was HSPgel RT MB-M (Waters Corporation), and the mixed solution was used as a developer at a column temperature of 50°C and a flow rate of 0.40 mL/min. The standard polystyrene used was TSK standard polystyrene manufactured by Tosoh Corporation.

<AC afterimage measurement/contrast measurement>
AC image retention was measured according to the method described in WO 2000/43833.
Specifically, the brightness-voltage characteristics (BV characteristics) of the prepared liquid crystal cell were measured, and these were designated as the brightness-voltage characteristics before the application of stress: B (before). Next, an AC of 4.5 V, 60 Hz was applied to the liquid crystal cell for 20 minutes, and then the cell was shorted for 1 second, and the brightness-voltage characteristics (BV characteristics) were measured again. These were designated as the brightness-voltage characteristics after the application of stress: B (after). Here, the brightness at a voltage of 1.3 V for each measured brightness-voltage characteristic was used to calculate the brightness change rate ΔB (%) according to the following formula. The smaller the value of ΔB (%), the more the occurrence of AC afterimages can be suppressed, i.e., the better the afterimage characteristics are.
If ΔB is 3% or less, it can be said that the afterimage characteristics are good. However, in recent years, the demand for better afterimage characteristics has increased, so a lower ΔB is preferable.
ΔB (%) = {[B (after) - B (before)] / B (before)} × 100
The AC image retention was evaluated according to the following criteria.
AC afterimage is 3% or less: 〇 AC afterimage is less than 3%: ×
In addition, the contrast (CR) was calculated using the ratio of the minimum luminance to the maximum luminance in the BV characteristics before the stress was applied. The larger the CR value, the clearer the bright and dark display and the better the contrast.
CR = B(before) _max / B(before) _min
In the formula, B(before) _max indicates the maximum luminance in the BV characteristics before the application of stress, and B(before) _min indicates the minimum luminance in the BV characteristics before the application of stress.
The contrast (CR) was evaluated according to the following criteria.
CR is 3000 or more: 〇 CR is less than 3000: ×

<Evaluation of Voltage Holding Ratio (VHR) Reliability>
The voltage holding ratio (VHR) of the liquid crystal display element was measured by applying a square wave of ±5V to the cell at 60°C according to the method described in "Mizushima et al., 14th Liquid Crystal Symposium Proceedings, p. 78 (1988)". The VHR at this time was taken as VHR (before). The voltage holding ratio is an index showing the extent to which the applied voltage is held after a frame period, and if this value is 100%, it means that all the charge is held. The cell was exposed to an LED backlight for 300 hours, and the VHR was measured again. The VHR at this time was taken as VHR (after).
The VHR reliability was evaluated based on the VHR drop rate calculated using the following formula: The smaller the VHR drop rate, the higher the VHR reliability and the higher the stability against light.
VHR decrease rate (%)
=|{[VHR(after)-VHR(before)]/VHR(before)}×100|
The VHR reliability was evaluated for the single-layer alignment film and the blend-type alignment film according to the following criteria: Single-layer alignment film VHR drop rate less than 5%: ◯ VHR drop rate 5% or more: ×
Blended alignment film VHR drop rate less than 3%: Good VHR drop rate 3% or more: Bad

<Tetracarboxylic acid dianhydride>

<Diamine>

<Solvent>
NMP: N-methyl-2-pyrrolidone BC: Butyl cellosolve (ethylene glycol monobutyl ether)
<Additives>
Additive 1: 1,3-bis(4,5-dihydro-2-oxazolyl)benzene

The compound represented by formula (1-1-1) was obtained by referring to the method described in International Publication No. WO 2014/046180.

The compound represented by formula (3-4-1) is a compound in which the two esters on the cyclopropane ring in formula (3-4) are in a trans configuration. The compound represented by formula (3-4-1) was obtained by referring to the method described in JP 2021-187841 A.

Preparation of Varnish The varnish used in this example was prepared by the following procedure. Here, varnishes A1 to A6 and R1 to R4 prepared in varnish preparation examples 1 to 10 are solutions of polyamic acid obtained by reacting at least one compound having a photoreactive chemical structure as a raw material. These varnishes exhibit anisotropy in the film by irradiating polarized light of an appropriate wavelength after film formation. Blend varnishes B1 to B4 prepared in varnish preparation examples 11 to 14 are solutions of polyamic acid obtained without using a compound having a photoreactive chemical structure as a raw material, and are blended with varnishes A1 to A6 or varnishes R1 to R4 to be used for preparing blend-type liquid crystal alignment agents (alignment agents 7 to 12 and comparative alignment agents 5 and 6 described below).

[Varnish Preparation Example 1] Preparation of Varnish A1 In a 100mL three-neck flask equipped with a stirring blade and a nitrogen inlet tube, 1.757g of the compound represented by formula (2-1-1) was placed, and 34.0g of N-methyl-2-pyrrolidone was added and stirred. Under a nitrogen atmosphere, 2.561g of the compound represented by formula (1-1-1) and 1.682g of the compound represented by formula (AN-4-17) (m = 8) were added to this solution, and the solution was stirred at room temperature for 12 hours. Thereto, 40.0g of NMP and 20.0g of BC were added, and the solution was heated and stirred at 60 ° C. until the weight average molecular weight of the solute polymer reached the desired weight average molecular weight, and a varnish A1 was obtained in which the weight average molecular weight of the solute was approximately 13,500 and the resin concentration (solid concentration) was 6% by weight.

[Preparation Examples 2 to 14 of Varnish] Preparation of Varnishes A2 to A6, Varnishes R1 to R4, and Varnishes B1 to B4 Varnishes A2 to A6 and comparative varnishes R1 to R4 with a solid content concentration of 6% by weight were prepared in the same manner as in Preparation Example 1, except that the compounds used as diamines and tetracarboxylic dianhydrides were changed as shown in Table 1. Varnishes B1 to B4 were prepared in the same manner as Preparation Example 1, except that the compounds used as diamines and tetracarboxylic dianhydrides were changed as shown in Table 2. In varnishes B1 to B4, the conditions of heating and stirring were adjusted so that the weight average molecular weight of the polymer was about 50,000. The weight average molecular weight of the generated polymer is shown in Tables 1 and 2. In Table 1, in a preparation example in which two or more compounds are listed as diamines, it means that all of the compounds were used together as diamines, and in a preparation example in which two or more compounds are listed as tetracarboxylic dianhydrides, it means that all of the compounds were used together as tetracarboxylic dianhydrides. The values in square brackets indicate the compounding ratio (mol %), and the blank spaces indicate that the corresponding compound was not used. The same applies to Table 2.

[Example 1]
<Preparation of Liquid Crystal Alignment Agent>
The varnish A1 was diluted with an NMP/BC mixed solution (NMP/BC=7/3 by weight ratio) so that the solid content concentration was 4% by weight, and the dilution was stirred to prepare an alignment agent 1.

<Contrast measurement and AC afterimage measurement>
The prepared alignment agent 1 was applied to a glass substrate with FFS electrodes and a glass substrate with column spacers by a spinner method. After application, the substrate was heated at 60°C for 80 seconds to evaporate the solvent, and then the substrate was irradiated with linearly polarized ultraviolet light from a vertical direction through a polarizing plate with a polarization wavelength range of 300nm to 450nm and a short wavelength cut filter with a cut-on wavelength of 280nm using a Multilight ML-501C/B manufactured by Ushio Inc. The exposure energy at this time was measured using an ultraviolet integrating light meter UIT-150 (photoreceiver: UVD-S365) manufactured by Ushio Inc., and the exposure time was adjusted so that the light amount was 2.0±0.1 J/ ^cm2 at a wavelength of 365 nm. Then, a baking process was performed at 220°C for 30 minutes to form an alignment film with a film thickness of approximately 100 nm. Next, the two substrates on which the alignment films were formed were bonded together with the surfaces on which the liquid crystal alignment films were formed facing each other, and a gap was provided between the facing liquid crystal alignment films for injecting the liquid crystal composition. At this time, the polarization directions of the linearly polarized light irradiated on each liquid crystal alignment film were parallel to each other. Positive liquid crystal composition A was injected into these cells to prepare liquid crystal cells (liquid crystal display elements) with a cell thickness of 5 μm.

（物性値）
相転移温度ＮＩ：１００．１℃、誘電率異方性Δε：５．１、屈折率異方性Δｎ：０．０９３、粘度η：２５．６ｍＰａ・ｓ． <Positive Liquid Crystal Composition A>

(Physical properties)
Phase transition temperature NI: 100.1° C., dielectric anisotropy Δε: 5.1, refractive index anisotropy Δn: 0.093, viscosity η: 25.6 mPa·s.

Using the prepared liquid crystal cell, AC afterimage measurement and contrast measurement were carried out according to the above-mentioned evaluation method "AC afterimage measurement and contrast measurement".
The evaluation results of AC afterimages and contrast for Examples 1 to 12 and Comparative Examples 1 to 6 are shown in Tables 3 and 4.

<VHR Reliability Evaluation>
The alignment agent 1 was applied to a glass substrate with an IPS electrode and a glass substrate with a column spacer by a spinner method. After application, the substrate was heated at 60° C. for 80 seconds to evaporate the solvent, and then the substrate was irradiated with linearly polarized ultraviolet light from a vertical direction through a polarizing plate with a polarization wavelength range of 300 nm to 450 nm and a short wavelength cut filter with a cut-on wavelength of 280 nm using a Multilight ML-501C/B manufactured by Ushio Inc. The exposure energy at this time was measured using an ultraviolet integrating light meter UIT-150 (photoreceiver: UVD-S365) manufactured by Ushio Inc., and the exposure time was adjusted so that the light amount was 2.0±0.1 J/cm ² at a wavelength of 365 nm. Then, a baking process was performed at 220° C. for 30 minutes to form a liquid crystal alignment film with a film thickness of approximately 100 nm.

Next, two substrates on which liquid crystal alignment films had been formed were bonded together with the surfaces on which the liquid crystal alignment films had been formed facing each other, and a gap for injecting the liquid crystal composition was formed between the opposing liquid crystal alignment films. At this time, the substrates were oriented so that the polarization directions of the linearly polarized light irradiated on each liquid crystal alignment film during the photo-alignment treatment were parallel to each other. Negative liquid crystal composition A, with the composition below, was injected into the gap between the bonded substrates, and a liquid crystal cell (liquid crystal display element) with a cell thickness of 7 μm was produced.

（物性値）
相転移温度ＮＩ：７５．７℃、誘電率異方性Δε：－４．１、屈折率異方性Δｎ：０．１０１、粘度η：１４．５ｍＰａ・ｓ． <Negative Liquid Crystal Composition A>

(Physical properties)
Phase transition temperature NI: 75.7° C., dielectric anisotropy Δε: −4.1, refractive index anisotropy Δn: 0.101, viscosity η: 14.5 mPa·s.

The liquid crystal cells thus fabricated were used to evaluate the VHR reliability according to the aforementioned evaluation method "Evaluation of Voltage Holding Ratio (VHR) Reliability." The evaluation results of the VHR reliability of Examples 1 to 12 and Comparative Examples 1 to 6 are shown in Tables 3 and 4.

[Example 2]
Alignment agent 2 was prepared in the same manner as in Example 1, except that varnish A2 was used instead of varnish A1, and additive 1 was added in an amount of 5 parts by weight based on the solid content at the same time as the addition of the NMP-BC mixed solution. A liquid crystal cell was prepared using alignment agent 2 in the same manner as in Example 1, and AC afterimage measurement, contrast measurement, and VHR reliability evaluation were performed.

[Example 3, Comparative Examples 1 and 2]
Except for using the varnish shown in Table 3 instead of varnish A1, alignment agent 3 and comparative alignment agents 1 and 2 were prepared in the same manner as in Example 1. For alignment agent 3 and comparative alignment agents 1 and 2, liquid crystal cells were prepared in the same manner as in Example 1, and AC afterimage measurement, contrast measurement, and VHR reliability evaluation were performed.

[Examples 4 to 6, Comparative Examples 3 and 4]
Alignment agents 4 to 6 and comparative alignment agents 3 and 4 were prepared in the same manner as in Example 1, except that the varnish shown in Table 3 was used instead of varnish A1. For alignment agents 4 to 6 and comparative alignment agents 3 and 4, linearly polarized ultraviolet light was irradiated from the vertical direction to the substrate through a polarizing plate having a polarization wavelength range of 230 nm to 310 nm, and the exposure energy was measured using a UV integrating light meter UIT-150 (receiver: UVD-S254) manufactured by Ushio Inc., and the exposure time of the linearly polarized light was adjusted so that the light amount was 0.5 ± 0.1 J / cm ² at a wavelength of 254 nm. A liquid crystal cell was prepared in the same manner as in Example 1, and AC afterimage measurement, contrast measurement, and VHR reliability evaluation were performed.

[Example 7]
Varnish A1 and varnish B1 were blended to a weight ratio of 3:7 to obtain a blend varnish with a solid content of 6 wt%. The blend was further diluted with an NMP-BC mixed solution (NMP/BC=7/3 weight ratio) to obtain a solid content of 4 wt%, and stirred to prepare alignment agent 7. A liquid crystal cell was prepared in the same manner as in Example 1, except that alignment agent 7 was used instead of alignment agent 1, and AC afterimage measurement, contrast measurement, and VHR reliability evaluation were performed.

[Example 8]
Alignment agent 8 was prepared in the same manner as in Example 7, except that varnish A2 was used instead of varnish A1, and additive 1 was added in an amount of 5 parts by weight based on the solid content at the same time as the addition of the NMP-BC mixed solution. A liquid crystal cell was prepared using alignment agent 8 in the same manner as in Example 1, and AC afterimage measurement, contrast measurement, and VHR reliability evaluation were performed.

[Example 9, Comparative Example 5]
Instead of varnish A1 and varnish B1, the varnishes shown in Table 4 were used to prepare alignment agent 9 and comparative alignment agent 5 in the same manner as in Example 7. For each of alignment agent 9 and comparative alignment agent 5, liquid crystal cells were prepared in the same manner as in Example 1, and AC afterimage measurement, contrast measurement, and VHR reliability evaluation were performed.

[Examples 10 to 12, Comparative Example 6]
Instead of varnish A1 and varnish B1, the varnishes shown in Table 4 were used to prepare alignment agents 10 to 12 and comparative alignment agent 6 in the same manner as in Example 7. For each of alignment agents 10 to 12 and comparative alignment agent 6, liquid crystal cells were prepared in the same manner as in Example 4, and AC afterimage measurement, contrast measurement, and VHR reliability evaluation were performed.

The AC image retention and contrast in Examples 1 to 12 were rated as "Good". By using a polymer made from a tetracarboxylic acid derivative represented by formula (1) as a liquid crystal alignment agent, a liquid crystal display element exhibiting excellent image retention and contrast was obtained. On the other hand, in Comparative Example 3, a formula (AN-4-21) that does not have a biphenyl skeleton was used, so a liquid crystal display element exhibiting excellent AC image retention and contrast could not be obtained. Comparative Examples 1 and 5, which used a formula (AN-4-33) that has only one benzene ring in the central skeleton, also had a contrast rating of "Bad", resulting in inferior results to the Examples that used formula (1).

The VHR reliability in Examples 1 to 12 was rated as "Good". By using a polymer made from a tetracarboxylic acid derivative represented by formula (1) as a liquid crystal alignment agent, a liquid crystal display element with excellent VHR reliability was obtained. On the other hand, in Comparative Examples 2, 4, and 6, which used formula (AN-4-37) having a biphenyl structure in the central skeleton but no substituent in the biphenyl portion, no twist occurred in the benzene ring of the biphenyl structure, and electronic conjugation of the polyimide chain was not suppressed, so a liquid crystal display element showing excellent VHR reliability could not be obtained. Note that in Examples 1 to 12, VHR (before), which is the VHR before exposure to the LED backlight, was 90% or more in all cases, showing sufficient VHR characteristics.

By using a liquid crystal alignment film formed using the liquid crystal alignment agent of the present invention, it is possible to obtain a liquid crystal display element that has good contrast and afterimage characteristics, and maintains a high voltage retention rate and does not deteriorate in display quality even when exposed to strong light for a long period of time. The liquid crystal alignment agent of the present invention can be suitably applied to a horizontal electric field type liquid crystal display element. In addition, by using the liquid crystal alignment agent of the present invention, a liquid crystal alignment film with high anisotropy can be obtained, which can be used as an optical compensation material, etc.

Claims (10)

A liquid crystal aligning agent comprising at least one polymer and a solvent, the at least one polymer being a polymer obtained by reacting a tetracarboxylic acid derivative with a diamine, the tetracarboxylic acid derivative comprising at least one selected from the group consisting of a compound represented by formula (1) and a compound derived therefrom.

In formula (1), R's each independently represent an alkyl group having 1 to 6 carbon atoms, and n's each independently represent an integer of 1 to 4. The liquid crystal alignment agent according to claim 1, wherein the raw material composition used as a raw material for the polymer obtained by reacting the tetracarboxylic acid derivative with a diamine contains at least one compound selected from the group consisting of the compound represented by formula (1) and its derivative compounds, and a compound having a photoreactive structure that imparts liquid crystal alignment to the alignment film by photoreaction. The liquid crystal alignment agent according to claim 2, wherein the photoreaction is at least one of photoisomerization, photo-Fries rearrangement, photodecomposition, and photodimerization. The liquid crystal aligning agent according to claim 2 , wherein the compound having a photoreactive structure is at least one compound represented by formula (2):

In formula (2), X is an alkylene having 1 to 12 carbon atoms, and one or more non-adjacent —(CH ₂ ) ₂ — groups in the alkylene may be replaced with —O— or —NH—;
R ^a and R ^b each independently represent a hydrogen atom, —CH ₃ , —OCH ₃ , —CF ₃ , —F, —COOCH ₃ , or a monovalent group represented by formula (P1-1) or formula (P1-2);
R ^c each independently represents hydrogen, —CH ₃ , —OCH ₃ , —CF ₃ , —F, or a monovalent group represented by formula (P1-1) or formula (P1-2); j is 0 or 1; a to c each independently represent an integer of 0 to 2;

In formula (P1-1) and formula (P1-2), R ^6a , R ^7a , and R ^8a each independently represent hydrogen, a substituted or unsubstituted alkyl, a substituted or unsubstituted alkanoyl, a substituted or unsubstituted alkoxycarbonyl, or a substituted or unsubstituted arylcarbonyl, R ^6a , R ^7a , and R ^8a may be the same or different, * represents the bonding position to the benzene ring in formula (2),
In formula (2), a group that is not bonded to any carbon atom constituting a ring indicates that the bond may be made to any position on the ring. The liquid crystal aligning agent according to claim 4, wherein the compound represented by formula (2) is any one of formulas (2-1) to (2-3).

In formula (2-1), R ^1a and R ^1c each independently represent a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2),
In formula (2-2), R ^2a and R ^2b each independently represent a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2); R ^2c each independently represent a hydrogen atom, -CH ₃ , -OCH ₃ , -CF ₃ , or -F;
X ₁ is an alkylene having 1 to 12 carbon atoms, in which one or more non-adjacent —(CH ₂ ) ₂ — groups in the alkylene may be replaced with —O— or —NH—, and k is an integer of 0 to 2;
In formula (2-3), R ^3a each independently represents hydrogen or a monovalent group represented by formula (P1-1) or formula (P1-2); R ⁴ and R ⁵ each independently represent hydrogen or -F, and R ⁴ and R ⁵ are not hydrogen at the same time; R ^3c each independently represents hydrogen, -CH ₃ , -OCH ₃ , -CF ₃ , or -F; X ₁ represents an alkylene having 1 to 12 carbon atoms, and one or more non-adjacent -(CH ₂ ) ₂ - of the alkylene may be replaced by -O- or -NH-; m represents an integer of 0 to 2;

In formula (P1-1) and formula (P1-2), R ^6a , R ^7a , and R ^8a each independently represent hydrogen, a substituted or unsubstituted alkyl, a substituted or unsubstituted alkanoyl, a substituted or unsubstituted alkoxycarbonyl, or a substituted or unsubstituted arylcarbonyl, R ^6a , R ^7a , and R ^8a may be the same or different, * represents the bonding position to the benzene ring in formula (2-1), formula (2-2), or formula (2-3),
In the formula (2-1), (2-2) or (2-3), a group that is not bonded to any carbon atom constituting a ring means that the bond position in the ring is optional. The liquid crystal aligning agent according to claim 2 , wherein the compound having a photoreactive structure is at least one compound represented by formula (3):

In formula (3), R ¹ and R ² each independently represent hydrogen, halogen, alkyl having 1 to 6 carbon atoms, haloalkyl having 1 to 6 carbon atoms, or alkoxy having 1 to 6 carbon atoms; R ¹ and R ² may be joined together to form an optionally substituted methylene; each X each independently represent halogen, alkyl having 1 to 6 carbon atoms, haloalkyl having 1 to 6 carbon atoms, or alkoxy having 1 to 6 carbon atoms; and n independently represent an integer of 0 to 4. The liquid crystal aligning agent according to claim 1, wherein the compound represented by formula (1) is represented by formula (1-1-1):

A liquid crystal alignment film formed from the liquid crystal alignment agent according to any one of claims 1 to 7. A liquid crystal element having the liquid crystal alignment film according to claim 8. A method for producing a liquid crystal alignment film, comprising the steps of applying the liquid crystal alignment agent according to any one of claims 2 to 7 to a substrate and irradiating the coating with polarized ultraviolet light.