JP7663449B2 - Liquid crystal alignment agent for forming a liquid crystal alignment film by a photo-alignment method, liquid crystal alignment film, and liquid crystal device using the same - Google Patents

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 photo-alignment (hereinafter sometimes abbreviated as 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.

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, solutions (varnishes) in which polyamic acid, soluble polyimide, or polyamic acid ester is dissolved in an organic solvent are mainly used to form such liquid crystal alignment films. To form liquid crystal alignment films using these varnishes, the varnish is applied to a substrate, and the coating is solidified by heating or other methods to form a polyimide-based liquid crystal alignment film, and an alignment treatment suitable for the display mode described above is performed 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 give the film anisotropy. Of these, the photoalignment method has the advantages of being more uniform in alignment than the rubbing method, not scratching the film because it is a non-contact alignment treatment method, and reducing 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, the applications of liquid crystal display elements have become diverse, including monitors for personal computers, liquid crystal televisions, mobile phones, displays for smartphones, and medical monitors. There is a demand for better display quality, and contrast is an important characteristic that affects display quality. In addition, in liquid crystal display elements that use liquid crystal alignment films produced using a photoalignment method, it is necessary to use liquid crystal alignment films that can produce good contrast even with short photoalignment times, i.e., photoalignment processes that use low exposure energy, in order to improve the efficiency of liquid crystal display element manufacturing.

The inventors therefore conducted extensive research with the objectives of providing a liquid crystal alignment film capable of forming a liquid crystal display element with excellent display quality and good contrast even when the exposure energy of the photo-alignment treatment is less than that of conventional methods, and of providing a liquid crystal alignment agent for photo-alignment 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 compound represented by formula (1-1) or formula (1-2), an alignment film having high liquid crystal alignment properties can be obtained, and that by using this alignment film, a liquid crystal display element having good contrast and excellent display quality can be formed, thereby completing the present invention.
The present invention includes the following configurations.

［２］ 前記光反応が、光異性化、光フリース転移、光分解、および光二量化のうち少なくとも１つである項１に記載の光配向用液晶配向剤。
［３］ 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、項１または２に記載の光配向用液晶配向剤。

式（２）においてＸは炭素数１～１２のアルキレン基であり、前記アルキレン基の炭素数が２以上の時、前記アルキレン基の－（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原子、メチル基、メトキシ基、トリフルオロメチル基、フッ素原子、メトキシカルボニル基、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原子、メチル基、メトキシ基、トリフルオロメチル基、フッ素原子、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、水素原子、置換もしくは無置換のアルキル基、置換もしくは無置換のアルカノイル基、または置換もしくは無置換のアルコキシカルボニル基を表し、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原子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。
［４］ 前記式（２）で表される化合物が、式（２－１）から式（２－３）のいずれか１つである、項３に記載の光配向用液晶配向剤。

式（２－１）において、Ｒ^１ａおよびＲ^１ｃは、それぞれ独立して、水素原子または式（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、水素原子または式（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原子、メチル基、メトキシ基、トリフルオロメチル基、フッ素原子であり、Ｘ_１は炭素数１～１２のアルキレン基であり、前記アルキレン基の炭素数が２以上の時、前記アルキレン基の－（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、水素原子または式（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、水素原子またはフッ素原子であり、Ｒ^４およびＲ^５が同時に水素原子となることはなく、Ｒ^3ｃはそれぞれ独立して水素原子、メチル基、メトキシ基、トリフルオロメチル基、フッ素原子であり、Ｘ_１は炭素数１～１２のアルキレン基であり、前記アルキレン基の炭素数が２以上の時、前記アルキレン基の－（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、水素原子、置換もしくは無置換のアルキル基、置換もしくは無置換のアルカノイル基、または置換もしくは無置換のアルコキシカルボニル基を表し、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原子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、項１または２に記載の光配向用液晶配向剤。

式（３）において、Ｒ^１及びＲ^２はそれぞれ独立して水素原子、ハロゲン原子、炭素数１から６のアルキル基、炭素数１から６のハロアルキル基または炭素数１から６のアルコキシ基を表し、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基を形成してもよく、Ｘはそれぞれ独立してハロゲン原子、炭素数１から６のアルキル基、炭素数１から６のハロアルキル基または炭素数１から６のアルコキシ基を表し、ｎは独立して０から４の整数を表す。
［６］ さらに、添加剤を含む、項１～５のいずれか１項に記載の光配向用液晶配向剤。
［７］ 前記添加剤が、オキサゾリン化合物およびエポキシ化合物からなる群から選ばれる少なくとも１つである、項６に記載の光配向用液晶配向剤。
［８］ 項１～７のいずれか１項に記載の光配向用液晶配向剤から形成される液晶配向膜。
［９］ 項８に記載の液晶配向膜を有する液晶素子。
［１０］ 項１～７のいずれか１項に記載の光配向用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 alignment agent for photoalignment, comprising at least one polymer and a solvent, wherein at least one of the polymers is a polymer obtained by reacting a tetracarboxylic dianhydride with a diamine,
A raw material composition used as a raw material for the polymer obtained by reacting the tetracarboxylic dianhydrides with the diamines contains at least one compound represented by formula (1-1) or formula (1-2) and a compound having a photoreactive structure that imparts liquid crystal alignment properties to an alignment film by photoreaction.

[2] The liquid crystal aligning agent for photo-alignment according to item 1, wherein the photoreaction is at least one of photoisomerization, photo-fries transition, photodecomposition, and photodimerization.
[3] The liquid crystal aligning agent for photo-alignment according to item 1 or 2, wherein the compound having a photoreactive structure is at least one compound represented by formula (2):

In formula (2), X is an alkylene group having 1 to 12 carbon atoms, and when the alkylene group has 2 or more carbon atoms, one or more non-adjacent —(CH ₂ ) ₂ — groups in the alkylene group may be replaced with —O— or —NH—;
R ^a and R ^b each independently represent a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, a fluorine atom, a methoxycarbonyl group, or a monovalent group represented by formula (P1-1) or formula (P1-2).
R ^c each independently represents a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, a fluorine atom, 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 a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or a substituted or unsubstituted alkoxycarbonyl group, 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 group may be bonded to any position on the ring.
[4] 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, a methyl group, a methoxy group, a trifluoromethyl group, or a fluorine atom; X ₁ represents an alkylene group having 1 to 12 carbon atoms, and when the alkylene group has 2 or more carbon atoms, one or more non-adjacent —(CH ₂ ) ₂ — groups in the alkylene group may be replaced with —O— or —NH—; k represents an integer of 0 to 2;
In formula (2-3), R ^3a each independently represents a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2); R ⁴ and R ⁵ each independently represent a hydrogen atom or a fluorine atom, and R ⁴ and R ⁵ are not simultaneously hydrogen atoms; R ^3c each independently represents a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, or a fluorine atom; X ₁ represents an alkylene group having 1 to 12 carbon atoms, and when the alkylene group has 2 or more carbon atoms, one or more non-adjacent -(CH ₂ ) ₂ - of the alkylene group may be replaced with -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 a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or a substituted or unsubstituted alkoxycarbonyl group, 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) and 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.
[5] The liquid crystal aligning agent for photo-alignment according to item 1 or 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 to form an optionally substituted methylene group; 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 independently represents an integer of 0 to 4.
[6] The liquid crystal aligning agent for photoalignment according to any one of items 1 to 5, further comprising an additive.
[7] The liquid crystal aligning agent for photo-alignment according to item 6, wherein the additive is at least one selected from the group consisting of oxazoline compounds and epoxy compounds.
[8] A liquid crystal alignment film formed from the liquid crystal alignment agent for photo-alignment according to any one of items 1 to 7.
[9] A liquid crystal element having the liquid crystal alignment film according to item 8.
[10] A method for producing a liquid crystal alignment film, comprising the steps of: applying the liquid crystal alignment agent for photo-alignment according to any one of items 1 to 7 to a substrate; and irradiating the coating with polarized ultraviolet light.

By using the liquid crystal alignment agent for photo-alignment of the present invention, a liquid crystal alignment film having high liquid crystal alignment properties can be obtained even when the exposure energy of the photo-alignment treatment is low. Furthermore, by using this liquid crystal alignment film, it is possible to efficiently manufacture liquid crystal display elements having good contrast and excellent display quality.

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. The "liquid crystal alignment agent" in the present invention is a liquid crystal alignment agent that can impart anisotropy by irradiating a polarized ultraviolet ray when the film is formed on a substrate, and is sometimes simply referred to as a "liquid crystal alignment agent" or a "liquid crystal alignment agent for photoalignment" in this specification. In addition, in the present invention, "tetracarboxylic dianhydrides" refer to tetracarboxylic dianhydrides, tetracarboxylic diesters, or tetracarboxylic diester dihalides. In the present invention, diamines and dihydrazides are sometimes referred to as "diamines".

<Liquid crystal alignment agent for photoalignment of the present invention>
The liquid crystal alignment agent for photo-alignment 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, which are obtained by reacting tetracarboxylic dianhydrides with diamines, and contains, as raw materials for the polymer, at least one compound represented by formula (1-1) or formula (1-2) and a compound having a photoreactive structure that imparts liquid crystal alignment properties to an alignment film by photoreaction. 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.

<Compound represented by formula (1-1) or formula (1-2)>
The compound represented by formula (1-1) or formula (1-2) used in the polymer contained in the liquid crystal aligning agent of the present invention will be described.

The tetracarboxylic dianhydrides used in the polymer contained in the liquid crystal aligning agent of the present invention may be all compounds represented by formula (1-1) or formula (1-2), or a compound represented by formula (1-1) and a compound represented by formula (1-2) may be used in combination. Furthermore, other tetracarboxylic dianhydrides described below may be used in combination, and in that case, the content of the other tetracarboxylic dianhydrides is preferably 5 mol% or more, and more preferably 20 mol% to 80 mol%, based on the total amount of tetracarboxylic dianhydrides in the monomer.

In the molecular structure of the compound represented by formula (1-1) or the compound represented by formula (1-2), the two dicarboxylic anhydride skeletons are present in the exo position relative to the norbornane ring to which they are bonded. In the compound represented by formula (1-1) or the compound represented by formula (1-2), there are stereoisomers in which one or two dicarboxylic anhydride skeletons are present in the endo position relative to the norbornane ring to which they are bonded. In the polymer using the compound represented by formula (1-1) and the polymer using the compound represented by formula (1-2), the anisotropy that appears in the liquid crystal alignment film by the alignment treatment is greater than when these stereoisomers are used, and they are more superior in terms of liquid crystal alignment properties.

<Compound having a photoreactive structure>
A compound having a photoreactive structure used as a raw material for the polymer contained in the liquid crystal alignment agent of the present invention will be described. 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 transition, photodecomposition, and photodimerization. By using a compound having a photoreactive structure as a raw material, the photoreactive structure can be incorporated into the 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 a liquid crystal alignment agent.

In the process of forming a liquid crystal alignment film, when a coating containing the liquid crystal alignment agent for photo-alignment of the present invention is irradiated with polarized light of a specified wavelength, the photoreactive structure of the polymer chains roughly parallel to the polarization direction undergoes a photoreaction, and the components of the polymer chains that are oriented in a specific direction (roughly perpendicular to the polarization direction of the irradiated light) become dominant, resulting in a coating film that is imparted with anisotropy. This state in which the components of the polymer chains that are oriented in a specific direction become dominant is expressed as the polymer chains being oriented. When the photoalignment film formed by baking this anisotropic 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原子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 on the benzene ring are each independently arbitrary, and a substitutable hydrogen atom on the benzene ring may be replaced with a substituent.

式（２）においてＸは炭素数１～１２のアルキレン基であり、前記アルキレン基の炭素数が２以上の時、前記アルキレン基の－（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原子、メチル基、メトキシ基、トリフルオロメチル基、フッ素原子、メトキシカルボニル基、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原子、メチル基、メトキシ基、トリフルオロメチル基、フッ素原子、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、水素原子、置換もしくは無置換のアルキル基、置換もしくは無置換のアルカノイル基、または置換もしくは無置換のアルコキシカルボニル基を表し、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原子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 photo-alignment liquid crystal aligning agent of the present invention is specifically a compound represented by formula (2).

In formula (2), X is an alkylene group having 1 to 12 carbon atoms, and when the alkylene group has 2 or more carbon atoms, one or more non-adjacent —(CH ₂ ) ₂ — groups in the alkylene group may be replaced with —O— or —NH—;
R ^a and R ^b are each independently a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, a fluorine atom, a methoxycarbonyl group, or a monovalent group represented by formula (P1-1) or formula (P1-2); R ^c are each independently a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, a fluorine atom, 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 a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or a substituted or unsubstituted alkoxycarbonyl group, 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 group may be bonded 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、水素原子、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、水素原子、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原子、メチル基、メトキシ基、トリフルオロメチル基、フッ素原子であり、Ｘ_１は炭素数１～１２のアルキレン基であり、前記アルキレン基の炭素数が２以上の時、前記アルキレン基の－（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、水素原子、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、水素原子または－Ｆであり、Ｒ^４およびＲ^５が同時に水素原子となることはなく、Ｒ^3ｃはそれぞれ独立して水素原子、メチル基、メトキシ基、トリフルオロメチル基、フッ素原子であり、Ｘ_１は炭素数１～１２のアルキレン基であり、前記アルキレン基の炭素数が２以上の時、前記アルキレン基の－（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、水素原子、置換もしくは無置換のアルキル基、置換もしくは無置換のアルカノイル基、または置換もしくは無置換のアルコキシカルボニル基を表し、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原子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 a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2); R ^2c each independently represent a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, or a fluorine atom; X ₁ represents an alkylene group having 1 to 12 carbon atoms, and when the alkylene group has 2 or more carbon atoms, one or more non-adjacent -(CH ₂ ) ₂ - of the alkylene group may be replaced with -O- or -NH-; k represents an integer of 0 to 2;
In formula (2-3), R ^3a each independently represents a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2); R ⁴ and R ⁵ each independently represent a hydrogen atom or -F, R ⁴ and R ⁵ are not simultaneously hydrogen atoms; R ^3c each independently represents a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, or a fluorine atom; X ₁ is an alkylene group having 1 to 12 carbon atoms, and when the alkylene group has 2 or more carbon atoms, one or more non-adjacent -(CH ₂ ) ₂ - of the alkylene group may be replaced by -O- or -NH-; m is an integer of 0 to 2;

In formula (P1-1) and formula (P1-2), R ^6a , R ^7a and R ^8a each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or a substituted or unsubstituted alkoxycarbonyl group, 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) and 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のアルキル基である。 Specific examples of the compound represented by formula (2-1) include the following compounds.

In formula (2-1-2), R ^6a is an alkyl group 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のアルキル基であり、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 formulas (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 an ethyl group.

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 an ethyl group 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 an ethyl group 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 more preferable to use one or more compounds selected from the group consisting of formulas (2-1-1), (2-2-1), and (2-2-2), and more preferable to use 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 formulas (2-1-1), (2-2-1), and (2-2-2) in the polymer is preferably 20 mol % to 100 mol %, and more preferably 40 mol % to 100 mol %, based on the total amount of diamines 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原子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、光フリース転移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、光フリース転移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－４－３６）、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原子、ハロゲン原子、炭素数１から６のアルキル基、炭素数１から６のハロアルキル基または炭素数１から６のアルコキシ基を表す。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基を形成してもよい。Ｘはそれぞれ独立してハロゲン原子、炭素数１から６のアルキル基、炭素数１から６のハロアルキル基または炭素数１から６のアルコキシ基を表し、ｎは０から４の整数を表す。式（ＤＩ－５－３５）におけるｍは、０から１２の整数を表す。 <Compound having a structure that causes a photo-fries transition reaction>
In the present invention, an example of a structure that causes a photo-fries transition reaction is a structure having a phenyl ester skeleton. In this specification, the structure having a phenyl ester skeleton means 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 atom of the benzene ring may be replaced with a substituent. A preferred example of a compound having a structure that causes a photo-induced Friess transition, 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 a photo-induced Friess transition reaction include compounds represented by formulas (AN-4-32) to (AN-4-36), (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 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. R ¹ and R ² may be joined together to form an optionally substituted methylene group. Each X independently represents 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 represents an integer from 0 to 4. In formula (DI-5-35), m represents an integer from 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 groups on each benzene ring in formula (3) are located in the para position relative to the ester group.

The total content of the compounds represented by formula (3) 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 causes a photodecomposition reaction in the present invention is a structure having a cyclobutanetetracarboxylic acid skeleton. In this specification, the structure having a cyclobutanetetracarboxylic acid skeleton means 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のアルキル基である。 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 independently represents an alkyl group 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原子は置換基で置き換えられていてもよい。 <Structure that causes photodimerization reaction>
In the present invention, an example of a structure that causes 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 a 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のアルキル基またはアルコキシ基であり、アルキル基またはアルコキシ基の少なくとも１つの水素原子はフッ素原子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 the compounds represented by the following formulas (PDI-9) to (PDI-13).

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

<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 diamine represented by formula (DI) and a tetracarboxylic dianhydride represented by formula (AN), 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 formula (1) or the other tetracarboxylic dianhydride column below. For the preferred range and specific examples of the divalent organic group in ^X2 , reference can be made to the corresponding structure of the diamine or dihydrazide described in formula (2) or the other diamine column below.

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基である。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基が好ましく、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基、またはターシャリーブチル基がより好ましい。 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 the liquid crystal alignment agent. Specific examples of such polyamic acid derivatives include 1) polyimides in which all amino groups and carboxyl groups 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 carboxyl groups of the polyamic acid are converted into esters, 4) polyamic acid-polyamide copolymers obtained by replacing a part of the acid dianhydride contained in a tetracarboxylic 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 group. 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 group having 1 to 6 carbon atoms, and more preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, or a tertiary butyl group.

Polyamic acids can be obtained as reaction products by polymerization reaction of tetracarboxylic dianhydrides and diamines. For explanations of tetracarboxylic dianhydrides, their preferred ranges, and specific examples, please refer to the description in the Tetracarboxylic Dianhydrides section below. For explanations of diamines, their preferred ranges, and specific examples, please refer to the description in the Diamines section below.

The tetracarboxylic dianhydrides and diamines used in the synthesis of the polyamic acid may each be one type or two or more types. The polyamic acid of the present invention can be obtained by using a compound represented by formula (1-1) or formula (1-2) as at least one of the tetracarboxylic dianhydrides, and further using a compound having a photoreactive structure that imparts liquid crystal alignment to the alignment film by photoreaction.

When the polyamic acid of the present invention is to be converted into a polyamic acid derivative, polyimide, the polyamic acid solution obtained can be imidized at a temperature of 20 to 150°C with an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride as a dehydrating agent, and a tertiary amine such as triethylamine, pyridine, or collidine as a dehydration ring-closing catalyst, to obtain a polyimide. Alternatively, a 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 isopropyl alcohol, or a glycol-based solvent), and the precipitated polyamic acid can be imidized in a solvent such as toluene or xylene with the above-mentioned dehydrating agent and dehydration ring-closing catalyst at a temperature of 20 to 150°C 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.

The polyamic acid ester can be obtained by a synthesis method of reacting a polyamic acid with a hydroxyl group-containing compound, a halide, an epoxy group-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. The tetracarboxylic acid diester derived from a tetracarboxylic acid dianhydride can be obtained, for example, by reacting the tetracarboxylic acid dianhydride with two equivalents of an alcohol to open the ring, and the tetracarboxylic acid diester dichloride can be obtained by reacting the 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 ester of the present invention can be obtained by using a compound represented by formula (1-1) or formula (1-2) as at least one of the tetracarboxylic acid dianhydrides, and further using a compound having a photoreactive structure that imparts liquid crystal alignment to the alignment film by photoreaction.

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 dianhydrides charged is preferably 0.9 to 1.1 moles per mole of diamines in total.

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 dianhydrides>
The tetracarboxylic dianhydrides other than the compounds represented by formula (1-1) or formula (1-2) used as the raw material for the polymer of the present invention can be selected from known tetracarboxylic dianhydrides 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のアルキレン基、１，４－フェニレン基、または１，４－シクロヘキシレン基である。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－の水素原子はメチル基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は独立して水素原子またはメチル基である。 [Tetracarboxylic acid dianhydride represented by formula (AN-1)]

In formula (AN-1), G ¹¹ is a single bond, an alkylene group having 1 to 12 carbon atoms, a 1,4-phenylene group, or a 1,4-cyclohexylene group. 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 atom of >CH-- may be substituted with a methyl group.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 a hydrogen atom or a methyl group.

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、水素原子、炭素数１～５のアルキル基、またはフェニル基である。 [Tetracarboxylic acid dianhydride represented by formula (AN-2)]

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

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。フェニレン基は、１，４－フェニレン基または１，３－フェニレン基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 single bond, or a divalent group represented by -O-, -CONH-, or -NHCO-. The phenylene group is preferably a 1,4-phenylene group or a 1,3-phenylene group.

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-4-31).

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

式（ＡＮ－５）において、Ｒ^１１は独立して水素原子またはメチル基である。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 a hydrogen atom or a methyl group. 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は水素原子、メチル基、エチル基、またはフェニル基である。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 a hydrogen atom, a methyl group, an ethyl group, or a phenyl group. 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 the 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つの水素原子は水酸基またはメチル基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 atom of the m -CH ₂ - may be replaced by a hydroxyl group or a methyl group. 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-, -(CH ₂ ) _m -NH-(CH ₂ ) _m -, -CO-(CH ₂ ) _k -NH-(CH ₂ ) _k -, -(NH-(CH ₂ ) _m ) _k -NH-, -CO-C ₃ H ₆ -(NH-C ₃ H ₆ ) _n -CO-, or -S-(CH ₂ ) _m -S-, 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-(CH ₂ ) _m -, -CO-(CH ₂ ) _k -NH-(CH ₂ ) _k -, -(NH-(CH ₂ ) _m ) _k -NH-, -CO-C ₃ H ₆ -(NH-C ₃ H ₆ ) _n -CO-, or -S-(CH ₂ ) _m -S-, -N(Boc)-(CH ₂ ) _e -N(Boc)-, -NH-(CH ₂ ) _e -N(Boc)-, -N(Boc)-(CH ₂ ) _e -, -(CH ₂ ) _m -N(Boc)-CONH-(CH ₂ ) _m -, -(CH ₂ ) _m -N(Boc)-(CH ₂ ) _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 a t-butoxycarbonyl group.

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 group having 1 to 10 carbon atoms.

At least one hydrogen atom of the cyclohexane ring and the benzene ring in formulae (DI-2) to (DI-7) may be substituted with a fluorine atom, a chlorine atom, an alkylene group having 1 to 3 carbon atoms, a -methoxy group, a hydroxyl group, a trifluoromethyl group, a carboxy group, a carbamoyl group, a phenylamino group, a phenyl group, or a benzyl group; in addition, in formula (DI-4), at least one hydrogen atom of 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 of 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は独立して水素原子またはメチル基である。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基である。 A group not fixed to a carbon atom constituting a ring indicates that the binding position in the ring is arbitrary. The binding position of the amino group to the cyclohexane ring or benzene ring is arbitrary except for the binding position of G ²¹ , G ²² or G ³³ .

In formulae (DI-4-a) and (DI-4-b), R ²⁰ independently represents a hydrogen atom or a methyl group. In formulae (DI-4-f) and (DI-4-g), m independently represents an integer of 0 to 12, and Boc represents a t-butoxycarbonyl group.

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は水素原子、水酸基、炭素数１～６のアルキル基、または炭素数１～６のアルコキシ基である。

In formula (DI-5-a), q is independently an integer of 0 to 6. R ⁴⁴ is a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group 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、環に結合するアミノ基の結合位置は、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 the amino group 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のアルキル基またはフェニル基であり、Ｇ^２３は独立して炭素数１～６のアルキレン基、フェニレン基またはアルキル基で置換されたフェニレン基であり、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のアルキル基、炭素数１～５のアルコキシ基または－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は水素原子、フッ素原子、塩素原子、炭素数１～６のアルキル基、アルコキシ基、アルケニル基、またはアルキニル基であり、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のアルキレン基または１，４－フェニレン基であり、ｒは０または１である。そして、環を構成する炭素原子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、環に結合するアミノ基の結合位置は、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 is an integer of 1 to 10.
In formula (DI-13), R ²³ independently represents an alkyl group having 1 to 5 carbon atoms, an alkoxy group 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 heterocyclic aromatic group, R ²⁴ is a hydrogen atom, a fluorine atom, a chlorine atom, an alkyl group, an alkoxy group, an alkenyl group, or an alkynyl group 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 group having 2 to 6 carbon atoms or a 1,4-phenylene group, and r is 0 or 1. A group that is not bonded to a carbon atom constituting a ring indicates that the bonding position in the ring is arbitrary. In formulas (DI-13) to (DI-16), the bonding position of the amino group 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), each k is independently an integer of 1 to 3. In formula (DI-1-9), each v is independently an integer of 1 to 6.

Examples of 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の整数である。

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 an integer of 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は水素原子、（ｔ－ブトキシカルボニル）アミノ基、またはビス（ｔ－ブトキシカルボニル）アミノ基である。式（ＤＩ－５－４２）～式（ＤＩ－５－４４）において、Ｂｏｃはｔ－ブトキシカルボニル基である。

In formulae (DI-5-42) to (DI-5-44), e is each independently an integer of 2 to 10, and in formula (DI-5-45), R ⁴³ is a hydrogen atom, a (t-butoxycarbonyl)amino group, or a bis(t-butoxycarbonyl)amino group. In formulae (DI-5-42) to (DI-5-44), Boc is a t-butoxycarbonyl group.

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のアルキレン基、－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つの水素原子はメチル基、エチル基、またはフェニル基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つの水素原子はメチル基、エチル基、またはフェニル基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のアルキレン基、－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－ヒドラジド基の結合位置は、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 group 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 atom of this group may be substituted with a methyl group, an ethyl group or a phenyl group.
In formula (DIH-3), each ring E is independently a cyclohexane ring or a benzene ring, and at least one hydrogen atom of this group may be substituted with a methyl group, an ethyl group, or a phenyl group. Multiple rings E may be the same or different. Y is a single bond, an alkylene group having 1 to 20 carbon atoms, -CO-, -O-, -S-, -SO ₂ -, -C(CH ₃ ) ₂ -, or -C(CF ₃ ) ₂ -.
In the formulae (DIH-2) and (DIH-3), the hydrazide group may be bonded to the ring at 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-, and an alkylene group having 1 to 3 carbon atoms, and particularly preferred examples are a single bond, -O-, -COO-, -OCO-, -CH ₂ O-, -CH ₂ -, and -CH ₂ CH ₂ -. R ²⁵ is an alkyl group having 3 to 30 carbon atoms, a phenyl group, a group having a steroid skeleton, or a group represented by the following formula (DI-31-a). In this alkyl group, at least one hydrogen atom may be substituted with a fluorine atom, and at least one -CH ₂ - may be substituted with -O-, -CH═CH- or -C≡C-. The hydrogen atom of this phenyl group may be substituted with a fluorine atom, a methyl group, a methoxy group, a fluoromethyloxy group, a difluoromethyloxy group, a trifluoromethyloxy group, an alkyl group having 3 to 30 carbon atoms or an alkoxy group having 3 to 30 carbon atoms. The bonding position of the amino group bonded to the benzene ring may be any position on the ring, but the bonding position is preferably the meta position or the 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のアルキレン基であり、このアルキレン基の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－フェニレン基、１，４－シクロへキシレン基、１，３－ジオキサン－２，５－ジイル基、ピリミジン－２，５－ジイル基、ピリジン－２，５－ジイル基、ナフタレン－１，５－ジイル基、ナフタレン－２，７－ジイル基またはアントラセン－９，１０－ジイル基であり、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つの水素原子はフッ素原子またはメチル基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は水素原子、フッ素原子、水酸基、炭素数１～３０のアルキル基、炭素数１～３０のフッ素置換アルキル基、炭素数１～３０のアルコキシ基、シアノ基、フルオロメチルオキシ基、ジフルオロメチルオキシ基、またはトリフルオロメチルオキシ基であり、この炭素数１～３０のアルキル基の少なくとも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のアルキル基であり、ｖは１～６の整数である。Ｒ^２６の好ましい例は炭素数１～３０のアルキル基および炭素数１～３０のアルコキシ基である。

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 group having 1 to 12 carbon atoms, and one or more -CH ₂ - in this alkylene group may be substituted with -O-, -COO-, -OCO-, -CONH- or -CH═CH-. Ring B ²¹ , ring B ²² , ring B ²³ and ring B ²⁴ are each independently a 1,4-phenylene group, a 1,4-cyclohexylene group, a 1,3-dioxane-2,5-diyl group, a pyrimidine-2,5-diyl group, a pyridine-2,5-diyl group, a naphthalene-1,5-diyl group, a naphthalene-2,7-diyl group or an anthracene-9,10-diyl group; in ring B ²¹ , ring B ²² , ring B ²³ and ring B ²⁴ , at least one hydrogen atom may be substituted with a fluorine atom or a methyl group; s, t and u are each independently an integer of 0 to 2, the sum of which is 1 to 5; and when s, t or u is 2, the two bonding groups in each parentheses may be the same or different, and the two rings may be the same or different. R ²⁶ is a hydrogen atom, a fluorine atom, a hydroxyl group, an alkyl group having 1 to 30 carbon atoms, a fluorine-substituted alkyl group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, a cyano group, a fluoromethyloxy group, a difluoromethyloxy group, or a trifluoromethyloxy group, and at least one —CH ₂ — in this alkyl group 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 an alkyl group having 1 to 3 carbon atoms, and v represents an integer of 1 to 6. Preferred examples of R ²⁶ include an alkyl group having 1 to 30 carbon atoms and an alkoxy group 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は独立して水素原子またはメチル基であり、Ｒ^３０は水素原子、炭素数１～２０のアルキル基、または炭素数２～２０のアルケニル基である。式（ＤＩ－３３）におけるベンゼン環の少なくとも１つの水素原子は、炭素数１～２０のアルキル基またはフェニル基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原子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アミノ基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 a hydrogen atom or a methyl group, and R ³⁰ is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an alkenyl group having 2 to 20 carbon atoms. At least one hydrogen atom of the benzene ring in formula (DI-33) may be substituted with an alkyl group having 1 to 20 carbon atoms or a phenyl group. A group not fixedly bonded to any carbon atom constituting the ring indicates that the bonded position in the ring is arbitrary. It is preferable that one of the two groups "-phenylene-G ³⁰ -O-" in formula (DI-32) is bonded to the 3-position of the steroid nucleus, and the other is bonded to the 6-position of the steroid nucleus. The bonding positions of the two groups "-phenylene-G ³⁰ -O-" in formula (DI-33) to the benzene ring are preferably meta or para relative to the bonding position of the steroid nucleus. In formulae (DI-32) and (DI-33), the amino group bonded to the benzene ring indicates that the bonding position in the ring may be any position.

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のアルキレン基であり、Ｇ^３２は単結合または炭素数１～３のアルキレン基である。Ｒ^３１は水素原子または炭素数１～２０のアルキル基であり、このアルキル基の少なくとも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のアルキル基であり、Ｒ^３３は水素原子または炭素数１～２２のアルキル基である。環Ｂ^２５は１，４－フェニレン基または１，４－シクロヘキシレン基であり、ｒは０または１である。そしてベンゼン環に結合するアミノ基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 an alkylene group having 1 to 6 carbon atoms, and G ³² is a single bond or an alkylene group having 1 to 3 carbon atoms. R ³¹ is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and at least one -CH ₂ - of this alkyl group may be replaced by -O-, -CH=CH- or -C≡C-. R ³² is an alkyl group having 6 to 22 carbon atoms, and R ³³ is a hydrogen atom or an alkyl group having 1 to 22 carbon atoms. Ring B ²⁵ is a 1,4-phenylene group or a 1,4-cyclohexylene group, and r is 0 or 1. The amino group bonded to the benzene ring may be bonded at any position in the ring, but is preferably independently bonded to the meta position or para position relative 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 an alkyl group having 1 to 30 carbon atoms or an alkoxy group having 1 to 30 carbon atoms, preferably an alkyl group having 5 to 25 carbon atoms or an alkoxy group having 5 to 25 carbon atoms. R ³⁵ is independently an alkyl group having 1 to 30 carbon atoms or an alkoxy group having 1 to 30 carbon atoms, preferably an alkyl group having 3 to 25 carbon atoms or an alkoxy group 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 an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms, preferably an alkyl group having 3 to 20 carbon atoms or an alkoxy group having 3 to 20 carbon atoms. R ³⁹ is independently a hydrogen atom, a fluorine atom, an alkyl group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, a cyano group, a fluoromethyloxy group, a difluoromethyloxy group, or a trifluoromethyloxy group, preferably an alkyl group having 3 to 25 carbon atoms or an alkoxy group having 3 to 25 carbon atoms. And G ³³ is an alkylene group 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原子または炭素数１～２０のアルキル基、好ましくは水素原子または炭素数１～１０のアルキル基であり、そしてＲ^４１はそれぞれ独立して水素原子または炭素数１～１２のアルキル基である。 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), R ⁴⁰ is independently a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ⁴¹ is independently a hydrogen atom or an alkyl group 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のアルキル基であり、Ｒ^４１はそれぞれ独立して水素原子または炭素数１～１２のアルキル基である。 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 each independently represents an alkyl group having 6 to 30 carbon atoms, and R ⁴¹ each independently represents 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のアルキル基である。 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 each independently represents 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 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, the coating properties of the liquid crystal alignment agent can be improved 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 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 that 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 that 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 simultaneously contain a compound having a photoreactive structure and a compound represented by formula (1-1) or formula (1-2).

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 with 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.

One way to induce layer separation is to reduce the molecular weight of the polymer that you want to segregate to the upper layer.

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

The compound represented by formula (1-1) or formula (1-2) 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 represented by formula (2) or formula (3) 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 tetracarboxylic acid dianhydride other than the compound represented by formula (1-1) or formula (1-2) 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), (AN-4-17), or (AN-4-21), more preferably formula (AN-4-17) or (AN-4-21). 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 other than the compound represented by formula (2) 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 without limitation from the known diamines exemplified above.

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-4-1), formula (DI-4-13), formula (DI-4-15), formula (DI-5-1), formula (DI-7-3), or formula (DI-13-1). Among them, 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 diamines used to synthesize 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 these, 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 (1-1) or formula (1-2) 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 producing two or more types of polyamic acid separately, mixing them, and heating them. Alternatively, two or more types of polyamic acid may be synthesized in the same reaction vessel, for example by synthesizing the first type of polyamic acid and then adding the raw material for the second type of polyamic acid to the same reaction vessel, and then heating them.

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 (1-1) or formula (1-2) 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.

Of 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 (Toki Sangyo TVE-20L type) (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 kinds. 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 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, and WO 2015/152014. 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 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 a 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 and polymers having epoxy rings can also be added. The oligomers and polymers having epoxy rings that can be used are 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 International Publication No. 2018/181566 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 those represented by the following formulae (HD-1) to (HD-4). The amount of these compounds is 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 for photoalignment 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 for photo-alignment 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 aligning 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 an electrode such as ITO (indium tin oxide), IZO (In ₂ O ₃ -ZnO), or IGZO (In-Ga-ZnO ₄ ) electrode, or a color filter, 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 that is 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 may 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 at different temperatures multiple times, it is preferable to fire 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 at 110°C and then at 220°C, fire at 110°C and then at 230°C, fire at 130°C and then at 220°C, fire at 150°C and then at 200°C, fire at 150°C and then at 220°C, fire at 150°C and then at 230°C, or fire at 170°C and then at 200°C. It is also preferable to fire at 200°C while gradually increasing the temperature by increasing the number of stages. When firing at 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 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 appropriately 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. In addition, examples of the annealing light used in the annealing treatment include UV lamps, fluorescent lamps, and LED lamps. 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 excellent 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 include those described in Japanese Patent No. 3,086,228, Japanese Patent No. 2,635,435, JP-A-5-501735, JP-A-8-157826, JP-A-8-231960, JP-A-9-241644 (EP 885,272 A1), JP-A-9-302,346 (EP 806,466 A1), and JP-A-8-199168 (EP 722,998 A1). ), 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 include 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, JP-A-10-236990, JP-A-10-236992, JP-A-10-236993, JP-A-10-236994, JP-A-10-237000, JP-A-10-237004, JP-A-10-237024, JP-A-10-237035, JP-A-10-237075, and JP-A-10-237076. , 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-2001-072626, JP-A-2001-192657, JP-A-2010-037428, WO 2011/024666, WO 2010/072370, JP-T-2010-537010, JP-A-2012-077201, JP-A-2009-084362, and the like.

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 WO 2015/146330 and the like.

A polymerizable compound can be mixed into the liquid crystal composition to make it compatible with 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 WO 2015/146330, etc.

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) 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), 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.

<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 Additive 2: (3,3',4,4'-diepoxy)bicyclohexyl

The compound represented by formula (1-1) was obtained by referring to the method described in International Publication No. 2019/172460.

The compound represented by formula (1-2) was obtained by referring to the method described in International Publication No. 2018/147373.

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 the following method.
A solution of diethyl trans-1,2-cyclopropanedicarboxylate (10.0 g, 53.7 mmol) in ethanol (100 mL) was ice-cooled, and then a solution of sodium hydroxide (8.60 g, 215 mmol) in water (100 mL) was added. The mixture was gradually warmed to room temperature over 1 hour, and then stirred for 15 hours. After the reaction was completed, the reaction mixture was concentrated under reduced pressure, and ethanol was distilled off. The residue was ice-cooled again, and concentrated hydrochloric acid (20 mL) was added, followed by the addition of an excess amount of sodium chloride, and extraction with ethyl acetate (100 mL x 8 times). The organic layer was dried over anhydrous sodium sulfate, and then concentrated under reduced pressure to obtain a white solid of trans-1,2-cyclopropanedicarboxylic acid (yield 6.44 g, 92%).
¹ H-NMR (400 MHz, DMSO-d ₆ ): δ1.89-1.77 (m, 2H), 1.26-1.14 (m, 2H).

Thionyl chloride (30 mL) was added to trans-1,2-cyclopropanedicarboxylic acid (6.00 g, 46.1 mmol), and the mixture was stirred at 70° C. for 4 hours, and then concentrated under reduced pressure to remove thionyl chloride, thereby obtaining crude trans-1,2-cyclopropanedicarboxylic acid chloride. This carboxylic acid chloride was made into a solution in THF (90 mL), and the entire amount was used in the next reaction.
Under an argon atmosphere, triethylamine (16.3 g, 161 mmol) was added to a solution of 4-nitrophenol (13.5 g, 96.8 mmol) in THF (100 mL) and the mixture was cooled on ice. While vigorously stirring this mixture, the THF solution of the carboxylic acid chloride prepared above was added over 5 minutes, and then the mixture was warmed to room temperature and stirred at room temperature for 2.5 hours. A saturated aqueous ammonium chloride solution (100 mL) was added to this reaction mixture and concentrated under reduced pressure. The residue was extracted with ethyl acetate (300 mL x 3 times) and then washed with saturated sodium bicarbonate (300 mL). The organic layer was dried over anhydrous sodium sulfate and then concentrated under reduced pressure to obtain a pale yellow solid (7.36 g) of trans-1,2-cyclopropanedicarboxylate di(4-nitrophenyl). Furthermore, the solid remaining in the aqueous layer was filtered and washed with water to recover a pale yellow solid (6.72 g) of di(4-nitrophenyl)trans-1,2-cyclopropanedicarboxylate. This was combined with the above 7.36 g to obtain dinitro compound 1 (di(4-nitrophenyl)trans-1,2-cyclopropanedicarboxylate) (total yield 14.1 g, 82% yield).
¹ H-NMR (400 MHz, CDCl ₃ ): δ8.31 (d, J=9.2 Hz, 4H), 7.35 (d, J=9.2 Hz, 4H), 2.66-2.59 (m, 2H), 1.86-1.78 (m, 2H).

Under an argon atmosphere, tin(II) chloride dihydrate (84.8 g, 376 mmol) was added to a solution of dinitro compound 1 (14.0 g, 37.6 mmol) in ethyl acetate (370 mL), and the mixture was stirred under heating and reflux for 4 hours. After the reaction was completed, the reaction mixture was cooled to room temperature, added to a saturated aqueous sodium bicarbonate solution (1 L), and then extracted with ethyl acetate (300 mL x 3 times). The resulting organic layer was washed with a saturated aqueous sodium bicarbonate solution (300 mL) and saturated saline (300 mL), dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography using a mixed solvent of chloroform:methanol as an eluent, changing the ratio in the range of 100:0 to 95:5, to obtain the desired diamine compound (3-4-1) as a white solid (yield 8.50 g, 72%). Since the starting material, diethyl trans-1,2-cyclopropanedicarboxylate, has enantiomers, it is presumed that the material thus obtained is actually a mixture of the compound represented by formula (3-4-1) and its enantiomer. However, in this Example, the two were used as they were without separating them.
¹ H-NMR (400 MHz, CDCl ₃ ): δ6.90 (d, J=8.8 Hz, 4H), 6.67 (d, J=8.8 Hz, 4H), 3.64 (brs, 4H), 2.53-2.47 (m, 2H), 1.71-1.65 (m, 2H).

Preparation of Varnish The varnish used in this example was prepared by the following procedure. Here, varnishes A1 to A7 and R1 to R3 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 B3 prepared in varnish preparation examples 11 to 13 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 A7 or varnishes R1 to R3 to be used for preparing blend-type liquid crystal alignment agents (alignment agents 7 to 11 and comparative alignment agents 4 to 5 described later).

[Varnish Preparation Example 1] Preparation of Varnish A1 2.058 g of the compound represented by formula (2-1-1) was placed in a 100 mL three-neck flask equipped with a stirring blade and a nitrogen inlet tube, and 34.0 g of N-methyl-2-pyrrolidone was added and stirred. 1.971 g of the compound represented by formula (1-1) and 1.971 g of the compound represented by formula (AN-4-17) (m = 8) were added to this solution, and the mixture was stirred at room temperature for 12 hours. 30.0 g of NMP and 30.0 g of BC were added thereto, 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 13,400 and the resin concentration (solid concentration) was 6 wt%.

[Preparation Examples 2 to 13 of Varnish] Preparation of Varnishes A2 to A7, Varnishes R1 to R3, and Varnishes B1 to B3 Varnishes A2 to A7 and comparative varnishes R1 to R3 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 B3 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 B3, 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]
Varnish A1 was diluted with an NMP-BC mixed solution (NMP/BC = 7/3 weight ratio) so that the solid content concentration was 4 wt%, and stirred to prepare alignment agent 1. The prepared liquid crystal alignment agent was applied to a glass substrate with an FFS 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 Electric Co., Ltd. The exposure energy at this time was measured using an ultraviolet integrating light meter UIT-150 (photoreceiver: UVD-S365) manufactured by Ushio Electric Co., Ltd., and the exposure time was adjusted so that the "standard exposure amount" was 2.0 ± 0.1 J/cm ² at a wavelength of 365 nm. Then, the substrate was baked at 220° C. for 30 minutes to form an alignment film with a thickness of about 100 nm. Next, the two substrates on which the alignment films were formed were laminated 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. 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. The brightness-voltage characteristics (BV characteristics) of the prepared liquid crystal cells were measured, and the contrast (CR) was calculated using the ratio of the minimum brightness to the maximum brightness. The larger the CR value, the clearer the light and dark display and the better the contrast.

CR= _Bmax / _Bmin
In the formula, B _max indicates the maximum luminance in the BV characteristics, and B _min indicates the minimum luminance in the BV characteristics.
The contrast (CR) was evaluated according to the following criteria.
CR is 3000 or more: 〇 CR is less than 3000: ×

Next, a liquid crystal cell was prepared in exactly the same manner, except that the exposure time was adjusted so that the amount of linearly polarized light was lower than the standard exposure amount, i.e., "low exposure amount" of 0.8±0.1 J/ ^cm2 , and the contrast was determined in the same manner. If the contrast is good at both the standard exposure amount and the low exposure amount, it means that the range of the suitable polarized light irradiation energy amount in the production of a liquid crystal display element is wider, and it means that it is more preferable as a liquid crystal alignment agent for photoalignment.
The evaluation results of the contrast in Examples 1 to 11 and Comparative Examples 1 to 5 are shown in Tables 3 and 4 together with the preparation conditions of the varnish.

[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 the contrast was measured and evaluated.

[Examples 3 to 5, Comparative Examples 1 to 2]
Alignment agents 3 to 5 and comparative alignment agents 1 and 2 were prepared in the same manner as in Example 1, except that the varnishes shown in Table 3 were used instead of varnish A1. For the alignment agents 3 to 5 and comparative alignment agents R1 and R2, liquid crystal cells were prepared in the same manner as in Example 1, and the contrast was measured and evaluated.

[Example 6, Comparative Example 3]
The alignment agent 6 and the comparative alignment agent R3 were prepared in the same manner as in Example 1, except that the varnish shown in Table 3 was used instead of the varnish A1. For the alignment agent 6 and the comparative alignment agent R3, the substrate was irradiated with linearly polarized ultraviolet light through a polarizing plate having a polarization wavelength range of 230 nm to 310 nm from the vertical direction, and the amount of light 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 "standard exposure 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 the contrast was measured and evaluated. Subsequently, a liquid crystal cell was prepared in exactly the same manner, except that the exposure time was adjusted so that the amount of linearly polarized light was lower than the standard exposure amount, that is, the "low exposure amount" was 0.2 ± 0.1 J / cm ² , and the contrast was also determined.

[Example 7]
Varnish A1 and varnish B1 were blended in 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 the contrast was measured and evaluated.

[Example 8]
Alignment agent 8 was prepared in the same manner as in Example 7, except that varnish A3 was used instead of varnish A1, and additive 2 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 the contrast was measured and evaluated.

[Examples 9 to 10, Comparative Example 4]
Alignment agents 9 to 10 and comparative alignment agent 4 were prepared in the same manner as in Example 7, except that the varnishes shown in Table 4 were used instead of varnish A1 and varnish B1, and the blend ratio was changed to that shown in Table 4. For example, the blend ratio "4:6" in Example 9 in Table 4 indicates that varnish A4 and blend varnish B2 were blended at a weight ratio of 4:6. For each of alignment agents 9 to 10 and comparative alignment agent 4, liquid crystal cells were prepared in the same manner as in Example 1, and the contrast was measured and evaluated.

[Example 11, Comparative Example 5]
Alignment agent 11 and comparative alignment agent 5 were prepared in the same manner as in Example 7, except that the varnishes shown in Table 4 were used instead of varnish A1 and varnish B1, and the blend ratio was changed to that shown in Table 4. For each of alignment agent 11 and comparative alignment agent 5, liquid crystal cells were prepared in the same manner as in Example 6, and the contrast was measured and evaluated.

（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.

The contrast in Examples 1 to 11 was evaluated as "good" for both the liquid crystal cells prepared with the standard exposure dose and the low exposure dose. It was found that by using a polymer obtained by polymerizing a tetracarboxylic dianhydride represented by formula (1-1) or formula (1-2) with a compound having a photoreactive structure as a liquid crystal alignment agent for photoalignment, an alignment film can be obtained that can realize a liquid crystal display element with high contrast even with a small exposure dose.

By using the liquid crystal alignment agent for photo-alignment of the present invention, it is possible to produce a liquid crystal alignment film that realizes a high-contrast liquid crystal display element even when the exposure energy of the photo-alignment treatment is low. The liquid crystal alignment agent for photo-alignment of the present invention can be suitably applied to a horizontal electric field type liquid crystal display element.

Claims (7)

A liquid crystal alignment agent for photoalignment, comprising at least one polymer and a solvent, wherein at least one of the polymers is a polymer obtained by reacting a tetracarboxylic dianhydride with a diamine,
A liquid crystal alignment agent for photo-alignment, comprising at least one compound represented by formula (1-1) or formula (1-2) and a compound having a photoreactive structure that imparts liquid crystal alignment properties to an alignment film by photoreaction, in a raw material composition used as a raw material for the polymer obtained by reacting the tetracarboxylic dianhydrides with the diamines,
The compound having a photoreactive structure is at least one of a compound represented by formula (2) and a compound represented by formula (3).

In formula (2), X is an alkylene group having 1 to 12 carbon atoms, and when the alkylene group has 2 or more carbon atoms, one or more non-adjacent —(CH ₂ ) ₂ — groups may be replaced with —O— or —NH—;
R ^a and R ^b each independently represent a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, a fluorine atom, a methoxycarbonyl group, or a monovalent group represented by formula (P1-1) or formula (P1-2).
R ^c each independently represents a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, a fluorine atom, 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 a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or a substituted or unsubstituted alkoxycarbonyl group, 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 fixed to any carbon atom constituting a ring indicates that the group may be bonded to any carbon atom in the ring.

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 to form an optionally substituted methylene group; 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 independently represents an integer of 0 to 4. The liquid crystal aligning agent for photoalignment according to claim 1 , 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, a methyl group, a methoxy group, a trifluoromethyl group, or a fluorine atom; X ₁ represents an alkylene group having 1 to 12 carbon atoms, and when the alkylene group has 2 or more carbon atoms, one or more non-adjacent -(CH ₂ ) ₂ - may be replaced by -O- or -NH-; k represents an integer of 0 to 2;
In formula (2-3), R ^3a each independently represents a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2); R ⁴ and R ⁵ each independently represent a hydrogen atom or a fluorine atom, and R ⁴ and R ⁵ are not simultaneously hydrogen atoms; R ^3c each independently represents a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, or a fluorine atom; X ₁ represents an alkylene group having 1 to 12 carbon atoms, and when the alkylene group has 2 or more carbon atoms, one or more non-adjacent -(CH ₂ ) ₂ - of the alkylene group may be replaced with -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 a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or a substituted or unsubstituted alkoxycarbonyl group, 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 formula (2-1), (2-2) or (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. The liquid crystal aligning agent for photo-alignment according to claim 1 or 2 , further comprising an additive. The liquid crystal aligning agent for photo-alignment according to claim 3 , wherein the additive is at least one selected from the group consisting of oxazoline compounds and epoxy compounds. A liquid crystal alignment film formed from the liquid crystal alignment agent for photo-alignment according to any one of claims 1 to 4 . A liquid crystal device comprising the liquid crystal alignment film according to claim 5 . A method for producing a liquid crystal alignment film, comprising the steps of: applying the liquid crystal aligning agent for photo-alignment according to any one of claims 1 to 4 to a substrate; and irradiating the coating with polarized ultraviolet light.