JP2025119568A - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal element - Google Patents

Abstract

To provide a liquid crystal alignment agent capable of achieving a liquid crystal device excellent in reliability and impurity resistance while difficult to cause a deposition of a polymer at idling while applying an inkjet coating.SOLUTION: A liquid crystal alignment agent includes a polymer (P) including a structural unit derived from a diamine expressed by formula (1) and being at least one kind selected from a group including a polyamic acid, a polyamic acid ester and a polyimide. In formula (1), R1 and R2 are a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms. However, at least one of R1 and R2 is a monovalent organic group having 1 to 6 carbon atoms. R3 and R4 are a hydrogen atom or a monovalent group having a nitrogen-containing heterocycle structure. However, at least one of R3 and R4 is a monovalent group having a nitrogen-containing heterocycle structure.SELECTED DRAWING: None

Description

The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal device.

Liquid crystal elements are equipped with a liquid crystal alignment film that functions to align the liquid crystal molecules in the liquid crystal layer in a specific direction. Liquid crystal alignment films are generally formed on substrates by applying a liquid crystal alignment agent, which is made by dissolving a polymer component in an organic solvent, to the substrate surface and then preferably heating the applied material.

In recent years, large-screen, high-definition LCD televisions have become mainstream, and small display devices such as smartphones and tablet PCs have become increasingly popular, resulting in greater demand for higher quality liquid crystal elements. Liquid crystal elements are also required to be highly reliable and to withstand little degradation during use. To address this, it has been proposed to use a diamine that can introduce a nitrogen-containing aromatic heterocycle, such as a pyridine ring, into the side chain of a polymer, and to incorporate a polymer containing structural units derived from this diamine into a liquid crystal aligning agent (see Patent Document 1).

LCD televisions have become increasingly popular in recent years, and large-scale lines known as "8th generation" and "10th generation" are now in operation. The advantages of using large lines to produce larger substrates include the ability to produce multiple panels from a single substrate, which reduces processing time and costs, and allows for larger LCD display elements. However, the disadvantage is that larger substrates make it difficult to ensure uniform printing of liquid crystal alignment agents over a large area. To address this issue, the use of inkjet coating methods to form liquid crystal alignment films is being considered.

The advantages of the inkjet coating method include the possibility of uniform application, as well as the potential for a reduction in the amount of liquid crystal alignment agent used, since the amount of liquid used during printing is essentially the same as the amount actually applied. Furthermore, because no printing plates are used, there is no need to replace or clean them, reducing the time, effort, and cost required for maintenance, and the flexibility to accommodate a variety of panel sizes.

Japanese Patent Application Laid-Open No. 2015-026052

The performance of liquid crystal elements (such as voltage holding ratio and film transmittance) is easily affected by impurities within the element. For example, if impurities are present in the liquid crystal alignment film that comes into contact with the liquid crystal molecules and dissolve into the liquid crystal, this can lead to a decrease in the performance of the liquid crystal element and reduce the reliability of the element.

In addition, high-definition liquid crystal panels such as 4K and 8K often have an insulating film. In liquid crystal panels with an insulating film, ionic impurities from the insulating film can leach into the liquid crystal through the liquid crystal alignment film. If ionic impurities leach into the liquid crystal, there is concern that the quality of the liquid crystal element will deteriorate, such as by reducing the voltage holding ratio. For this reason, liquid crystal alignment films are required to have excellent performance (hereinafter referred to as "impurity resistance") that prevents impurities generated within the element from penetrating into the liquid crystal and prevents a decrease in the voltage holding ratio caused by impurities.

Furthermore, when attempting to improve the performance of liquid crystal devices by introducing a nitrogen-containing aromatic heterocycle into a liquid crystal alignment film, as in Patent Document 1, it is thought that a decrease in solubility may occur due to interactions between the functional groups (e.g., carboxy groups) of the polymer component and the nitrogen-containing aromatic heterocycle. Therefore, when forming a liquid crystal alignment film on a substrate by inkjet coating, there is a concern that the polymer component in the liquid crystal alignment agent may be more likely to precipitate in the inkjet head portion while the inkjet coating device is idling. Furthermore, if the polymer component precipitates in the head portion, there is a concern that the inkjet may become clogged, reducing coating performance, or that the precipitates may reduce the surface uniformity of the film.

The present invention was developed in consideration of the above-mentioned problems, and one of its objectives is to provide a liquid crystal alignment agent that is less likely to cause polymer precipitation during idling during inkjet coating and that can produce liquid crystal devices with excellent reliability and impurity resistance.

According to one aspect of the present invention, there is provided a liquid crystal aligning agent containing a polymer (P) which is at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide and which contains a structural unit derived from a diamine represented by the following formula (1):
(In formula (1), ^R1 and ^R2 are each independently a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms, provided that at least one of ^R1 and ^R2 is a monovalent organic group having 1 to 6 carbon atoms. ^R3 and ^R4 are each independently a hydrogen atom or a monovalent group having a nitrogen-containing heterocyclic structure, provided that at least one of ^R3 and ^R4 is a monovalent group having a nitrogen-containing heterocyclic structure.)

In another aspect, the present invention provides a liquid crystal alignment film formed using the liquid crystal alignment agent described above in [1]. In another aspect, the present invention provides a liquid crystal element including the liquid crystal alignment film described above in [2].

In another aspect, the present invention provides a polymer that is a polyamic acid, a polyamic acid ester, or a polyimide and includes structural units derived from the diamine represented by formula (1) above. In another aspect, the present invention provides a diamine represented by formula (1) above.

The liquid crystal aligning agent of the present invention can prevent polymer precipitation from occurring in the inkjet head during idling during inkjet coating. Furthermore, the liquid crystal aligning agent of the present invention can provide liquid crystal devices with excellent reliability and impurity resistance.

FIG. 2 is a diagram showing an electrode pattern of a transparent electrode film used in Examples and Comparative Examples.

The following provides a detailed explanation of matters related to aspects of this disclosure.

In this specification, numerical ranges indicated using "to" include the numerical values before and after "to" as the lower and upper limits. A "structural unit" refers to a unit that primarily constitutes the main chain structure, and at least two or more of which are contained in the main chain structure. A structural unit is typically a repeating unit composed of a single monomer. Note that a structural unit may be obtained by reacting a repeating unit having a reactive group with a compound having a functional group capable of reacting with the reactive group.

As used herein, the term "hydrocarbon group" includes chain hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. A "chain hydrocarbon group" refers to a linear hydrocarbon group or a branched hydrocarbon group that does not contain a cyclic structure and is composed solely of a chain structure. However, it may be saturated or unsaturated. An "alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic hydrocarbon structure as a ring structure and does not contain an aromatic ring structure. However, it does not necessarily have to be composed solely of an alicyclic hydrocarbon structure, and it may also contain a chain structure as part of its structure. An "aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as a ring structure. However, it does not necessarily have to be composed solely of an aromatic ring structure, and it may contain a chain structure or an alicyclic hydrocarbon structure as part of its structure. An "organic group" refers to an atomic group formed by removing any hydrogen atom from a carbon-containing compound (i.e., an organic compound).

The "main chain" of a polymer refers to the "trunk" portion of the polymer, which is made up of the longest chain of atoms. It is permissible for this "trunk" portion to contain a ring structure. For example, "having a specific structure in the main chain" means that the specific structure constitutes part of the main chain. A "side chain" refers to a portion branching off from the "trunk" portion of the polymer.

<Liquid crystal alignment agent>
The liquid crystal aligning agent of the present disclosure contains a polymer (P) which is at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide, and which contains a structural unit derived from a diamine represented by the following formula (1) (hereinafter also referred to as a “specific diamine”):
(In formula (1), ^R1 and ^R2 are each independently a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms, provided that at least one of ^R1 and ^R2 is a monovalent organic group having 1 to 6 carbon atoms. ^R3 and ^R4 are each independently a hydrogen atom or a monovalent group having a nitrogen-containing heterocyclic structure, provided that at least one of ^R3 and ^R4 is a monovalent group having a nitrogen-containing heterocyclic structure.)

The polymer (P) contained in the liquid crystal aligning agent of the present disclosure and the optional components that are blended as needed are described in detail below. Unless otherwise specified, each component may be used alone or in combination of two or more.

<Polymer (P)>
The polymer (P) is a polymer having a polyamic acid, polyamic acid ester, or polyimide as a main skeleton, and contains a structural unit derived from a specific diamine. In the above formula (1), examples of the monovalent organic group having 1 to 6 carbon atoms represented by ^R1 or ^R2 include monovalent hydrocarbon groups having 1 to 6 carbon atoms, groups having 1 to 6 carbon atoms in which any methylene group in a monovalent hydrocarbon group has been replaced by a heteroatom-containing group such as -O-, -S-, -CO-, ^-COO- , -OCO-, ^-NR10- , ^-NR10 -CO-, -CO- ^NR10- , -O-CO- ^NR10- , ^-NR10 -CO-O-, or -NR10-CO- ^NR11- (hereinafter referred to as "group R ^a "), and groups having 1 to 6 carbon atoms in which any hydrogen atom in a monovalent hydrocarbon group or group R ^a has been replaced by a substituent. Here, R ¹⁰ and R ¹¹ are each independently a hydrogen atom or a monovalent hydrocarbon group.

Examples of monovalent hydrocarbon groups having 1 to 6 carbon atoms include linear or branched alkyl groups having 1 to 6 carbon atoms, linear or branched alkenyl groups having 2 to 6 carbon atoms, linear or branched alkynyl groups having 2 to 6 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 6 carbon atoms, and phenyl groups.

Specific examples of alkyl groups having 1 to 6 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, tert-pentyl, n-hexyl, and isohexyl. Examples of linear or branched alkenyl groups having 2 to 6 carbon atoms include ethenyl, 1-propenyl, 2-propenyl, 1-butenyl, and 2-butenyl. Examples of linear or branched alkynyl groups having 2 to 6 carbon atoms include ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, and 2-butynyl.

Examples of monovalent alicyclic hydrocarbon groups having 3 to 6 carbon atoms include groups having a saturated or unsaturated alicyclic monocyclic hydrocarbon structure having 3 to 6 carbon atoms as the ring structure. Specific examples of rings in alicyclic hydrocarbon groups include cyclopentane, cyclohexane, cyclopentene, and cyclohexene.

When the group represented by ^R1 or ^R2 has a substituent, examples of the substituent include a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.), a hydroxyl group, a cyano group, a nitro group, a carboxy group, -NR ¹² R ¹³ (wherein R ¹² and R ¹³ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms), etc. Specific examples when R ¹² and ^{R 13} are alkyl groups include the same groups as the specific examples when R ¹ or R 2 is an alkyl group having 1 to 6 carbon atoms.

The monovalent organic group having 1 to 6 carbon atoms represented by ^R1 or ^R2 is preferably an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a phenyl group, -COR5 or -NR6R7 (wherein R5, R6 and R7 are each independently an alkyl group having 1 to 3 carbon atoms; the same applies hereinafter) in terms of maintaining high reactivity (i.e., polymerizability) when synthesizing the polymer (P), being highly effective in suppressing precipitation of the polymer in the liquid crystal alignment agent at the head portion during idling of the inkjet coating device when forming a liquid ^crystal alignment ^film on a substrate ^by inkjet coating, ^and being able to provide excellent reliability and impurity resistance of the liquid crystal element. Furthermore, from the viewpoints ^of polymerizability and ease of availability, ^an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms or a phenyl group is more preferred, a methyl group, an ethyl group or a methoxy group is even more preferred, and a methyl group is even more preferred.

In the following, when a liquid crystal alignment agent is applied to a substrate by inkjet coating to form a liquid crystal alignment film, the property of the liquid crystal alignment agent that suppresses polymer deposition in the head portion while the inkjet coating device is idling is also referred to as "idling resistance during inkjet coating" or simply "idling resistance."

One or both of ^R1 and ^R2 are monovalent organic groups having 1 to 6 carbon atoms. That is, combinations of ^R1 and ^R2 include a case where ^R1 is a monovalent organic group having 1 to 6 carbon atoms and ^R2 is a hydrogen atom; a case where ^R1 is a hydrogen atom and ^R2 is a monovalent organic group having 1 to 6 carbon atoms; and a case where ^R1 and ^R2 are both monovalent organic groups having 1 to 6 carbon atoms. R1 is preferably a monovalent organic group having 1 to 6 carbon atoms because this makes it difficult for the polymer to precipitate even when a base component (more specifically, a nitrogen-containing heterocycle ⁾ is introduced into the polymer side chain, thereby enabling the production of a liquid crystal aligning agent with superior idling resistance during inkjet coating. In this case, ^R2 may be either a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms, but from the viewpoint of balancing the effect of introducing a structural unit derived from the specific diamine and the ease of synthesis of the specific diamine, ^R2 is preferably a hydrogen atom.

In view of the introduction of the specific diamine unit enabling a higher effect of improving idling resistance during inkjet coating and the reliability and impurity resistance of liquid crystal elements, at least one of R ¹ and R ² is preferably an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a phenyl group, -COR ⁵ or -NR ⁶ R ⁷ , and more preferably R ¹ is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a phenyl group, -COR ⁵ or -NR ⁶ R ⁷ , and R ² is a hydrogen atom. Furthermore, in view of polymerizability and ease of compound availability, when R ² is a hydrogen atom, R ¹ is more preferably an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms or a phenyl group, and even more preferably a methyl group, an ethyl group or a methoxy group.

In the monovalent group having a nitrogen-containing heterocyclic structure represented by ^R3 or ^R4 (hereinafter also referred to as a "monovalent heterocyclic structure-containing group"), the nitrogen-containing heterocyclic ring of the nitrogen-containing heterocyclic structure may have only a nitrogen atom as a heteroatom constituting the ring, or may further have a heteroatom other than a nitrogen atom (for example, an oxygen atom or a sulfur atom). In addition, the nitrogen-containing heterocycle may be an aromatic ring or a non-aromatic ring.

Specific examples of the aromatic ring include pyrrole, indole, imidazole, benzimidazole, oxazole, thiazole, pyrazole, triazole, pyridine, pyrimidine, pyridazine, pyrazine, quinoline, isoquinoline, carbazole, azatropylidene, purine, benzo[d]oxazole, benzo[d]thiazole, and compounds represented by the following formula:
Examples include rings represented by the following formula:

Specific examples of non-aromatic ring structures include an ethyleneimine ring structure, a pyrrolidine ring structure, a piperidine ring structure, a piperazine ring structure, a hexamethyleneimine ring structure, a 3-pyrroline ring structure, a 2-pyrroline ring structure, a 2-imidazoline ring structure, an indoline ring structure, a 2-pyrazoline ring structure, and a succinimide ring structure.

The nitrogen-containing heterocyclic structure may have only one nitrogen-containing heterocycle, or may have two or more nitrogen-containing heterocycles. When the nitrogen-containing heterocyclic structure has two or more nitrogen-containing heterocycles, the two or more nitrogen-containing heterocycles may be linked to each other by a single bond, or may be linked via a divalent linking group (for example, —NR ¹² — or —NR ¹² —R ¹³ —NR ¹² — (wherein R ¹² is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a tert-butoxycarbonyl group, and R ¹³ is an alkanediyl group having 1 to 3 carbon atoms)).

The nitrogen-containing heterocycle in the monovalent heterocyclic structure-containing group may have a substituent, such as a halogen atom, a hydroxyl group, a cyano group, a nitro group, a carboxyl group, —NR ¹³ R ¹⁴ (wherein R ¹³ and R ¹⁴ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms), or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

In order to further improve the reliability and impurity resistance of the liquid crystal device, the monovalent heterocyclic structure-containing group represented by ^R3 or ^R4 preferably has a nitrogen-containing aromatic heterocycle. In order to further improve the reliability and impurity resistance of the liquid crystal device, the nitrogen-containing aromatic heterocyclic structure preferably has at least one ring selected from the group consisting of pyrrole, indole, benzimidazole, oxazole, thiazole, triazole, pyridine, pyrimidine, quinoline, isoquinoline, azatropylidene, and purine, more preferably has at least one ring selected from the group consisting of pyridine, benzimidazole, triazole, and purine, and even more preferably has at least one of pyridine and benzimidazole.

Specific examples of the monovalent heterocyclic structure-containing group include groups represented by the following formula (2).
(In formula (2), ^X1 is a single bond or an (n+1)-valent linking group. ^Y1 is a monovalent group bonded to ^X1 via a nitrogen-containing heterocycle. n is 1 or 2. However, when ^X1 is a single bond, n is 1.)

In the above formula (2), examples of the monovalent group represented by ^Y1 include a group in which one hydrogen atom has been removed from a substituted or unsubstituted nitrogen-containing heterocycle; and a group in which two or more (preferably two) substituted or unsubstituted nitrogen-containing heterocycles are bonded by a single bond or a divalent linking group, and one hydrogen atom has been removed from any one of the nitrogen-containing heterocycles. Examples of the nitrogen-containing heterocycle include the rings exemplified above. The nitrogen-containing heterocycle is preferably a nitrogen-containing aromatic heterocycle.

Specific examples of the monovalent group represented by Y ¹ include partial structures represented by the following formulas.
(In the formula, "*" represents a bond.)

Specific examples of the (n+1)-valent linking group represented by X ¹ when n is 1 (that is, when X ¹ is a divalent linking group) include, for example, -O-, -CO-, *-CO-O-, *-O-CO-, -NH-, *-CO-NH-, *-NH-CO-, *-(CH ₂ ) _r -O-, *-O-(CH 2 ) _r -, *-(CH ₂ ) _r -CO-, *-CO-(CH ₂ ) _r -, *-(CH _{2 ) r} -NH-, *-NH-(CH ₂ ) _r -, *-(CH ₂ ) _r -CO-NH-, *-CO-NH-(CH ₂ ) _r -, *-CO-NH-R ¹⁴ -O-, *-O-R ¹⁴ -CO-NH-, an alkanediyl group having 1 to 10 carbon atoms, a phenyl group, or a group in which two or more of these groups are bonded (wherein r is an integer of 1 to 3, ^R is a divalent hydrocarbon group having 1 to 10 carbon atoms, and "*" represents a bond to the benzene ring in the above formula (1)).
Specific examples when n is 2 (that is, when X ¹ is a trivalent linking group) include *-N<, *-CO-N<, *-(CH ₂ ) _r -CO-N<, *-O-R ¹⁴ -CO-N<, and the like.

One or both of ^R3 and ^R4 are monovalent heterocyclic structure-containing groups. From the viewpoint of the balance between the effect of introducing a structural unit derived from the specific diamine and the ease of synthesis of the specific diamine, it is preferred that one of ^R3 and ^R4 is a monovalent heterocyclic structure-containing group and the other is a hydrogen atom.

Preferable specific examples of the specific diamine include a compound represented by the following formula (1-A) and a compound represented by the following formula (1-B).
(In the above formulas (1-A) and (1-B), R ¹ has the same meaning as in the above formula (1). ^{X 1} , Y ¹ and n have the same meaning as in the above formula (2).)

Specific examples of the specific diamine include compounds represented by the following formulas (1-1) to (1-28).

The content of structural units derived from specific diamines in polymer (P) is preferably 2 mol% or more, and more preferably 5 mol% or more, based on the total amount of structural units derived from diamine compounds contained in polymer (P). Furthermore, the content of structural units derived from specific diamines is preferably 70 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less, based on the total amount of structural units derived from diamine compounds contained in polymer (P). By keeping the content of structural units derived from specific diamines within the above range, polymerizability can be ensured while the liquid crystal aligning agent exhibits excellent idling resistance during inkjet coating, as well as excellent reliability and impurity resistance of the liquid crystal device.

[Synthesis of specific diamine]
The specific diamine can be synthesized by appropriately combining standard methods in organic chemistry. One example of a method for synthesizing the specific diamine is to first synthesize a dinitro intermediate having a nitro group instead of the primary amino group in the target diamine, and then aminated by using an appropriate reduction system.

The method for synthesizing the dinitro intermediate can be appropriately selected depending on the molecular structure of the target diamine. For example, the compound represented by the above formula (1-A) or formula (1-B) can be obtained by reacting a first compound having ^R1 and a first reactive group (e.g., a carboxy group, a hydroxyl group, a halocarbonyl group, etc.) bonded to the benzene ring of a dinitrophenyl group with a second compound having a second reactive group capable of reacting with the first reactive group and ^Y1 . The reduction reaction of the dinitro intermediate can be preferably carried out in an organic solvent using a catalyst such as palladium carbon, platinum carbon, zinc, iron, tin, or nickel. Examples of organic solvents used here include ethyl acetate, toluene, tetrahydrofuran, and alcohols. However, the method for synthesizing the specific diamine is not limited to the above.

[Synthesis of Polymer (P)]
The synthesis method of the polymer (P) is not particularly limited. The polymer (P) can be obtained, for example, by polycondensation of a tetracarboxylic acid derivative and a diamine compound. The tetracarboxylic acid derivative includes tetracarboxylic acid dianhydrides, tetracarboxylic acid dihalides, and tetracarboxylic acid diester dihalides. The polyamic acid, polyamic acid ester, and polyimide will be described below.

(Polyamic acid)
When the polymer (P) is a polyamic acid, the polyamic acid (hereinafter also referred to as "polyamic acid (P)") can be obtained by reacting (polycondensation reaction) a tetracarboxylic dianhydride with a diamine compound containing a specific diamine.

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

Specific examples of the tetracarboxylic acid dianhydride include chain tetracarboxylic acid dianhydrides such as 1,2,3,4-butanetetracarboxylic acid dianhydride and ethylenediaminetetraacetic acid dianhydride;
Examples of alicyclic tetracarboxylic dianhydrides include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 5-(2,5-dioxotetrahydrofuran-3-yl)-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 5-(2,5-dioxotetrahydrofuran-3-yl)-8-methyl-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 3-oxabicyclo[3 2.1]octane-2,4-dione-6-spiro-3'-(tetrahydrofuran-2',5'-dione), 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2:3,5:6-dianhydride, bicyclo[3.3.0]octane-2,4,6,8-tetracarboxylic acid 2:4,6:8-dianhydride, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic acid 2:3,5:6-dianhydride, 4,9-dioxatricyclo[5.3.1.0]octane-2,4,6,8-tetracarboxylic acid 2:3,5:6-dianhydride ^2,6 ]undecane-3,5,8,10-tetraone, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, etc.;
Examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, p-phenylene bis(trimellitic acid monoester anhydride), ethylene glycol bis(anhydrotrimellitate), 1,3-propylene glycol bis(anhydrotrimellitate), 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 4,4'-biphthalic dianhydride, 4,4'-oxydiphthalic dianhydride, and 4,4'-carbonyldiphthalic anhydride; and in addition, the tetracarboxylic dianhydrides described in JP-A-2010-97188 can be used.

The tetracarboxylic acid dianhydride preferably includes an aliphatic tetracarboxylic acid dianhydride, and more preferably an alicyclic tetracarboxylic acid dianhydride, since this allows for the production of a liquid crystal alignment film with good voltage retention characteristics. Specifically, it is preferable for the tetracarboxylic acid dianhydride to include at least one selected from the group consisting of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 2,4,6,8-tetracarboxybicyclo[3.3.0]octane-2:4,6:8-dianhydride, cyclopentanetetracarboxylic acid dianhydride, and cyclohexanetetracarboxylic acid dianhydride.

When synthesizing polyamic acid (P), the amount of alicyclic tetracarboxylic dianhydride used is preferably 20 mol % or more, more preferably 30 mol % or more, and even more preferably 50 mol % or more, based on the total amount of tetracarboxylic dianhydride constituting polyamic acid (P).

Diamine Compound When synthesizing the polyamic acid (P), only the specific diamine may be used as the diamine compound. Alternatively, the specific diamine may be used in combination with a diamine other than the specific diamine (hereinafter also referred to as "other diamine"). Examples of other diamines include aliphatic diamines, aromatic diamines, and diaminoorganosiloxanes. Examples of aliphatic diamines include linear diamines and alicyclic diamines.

Specific examples of other diamines include chain diamines such as metaxylylenediamine and hexamethylenediamine; alicyclic diamines such as 1,4-diaminocyclohexane and 4,4'-methylenebis(cyclohexylamine); and diaminoorganosiloxanes such as 1,3-bis(3-aminopropyl)-tetramethyldisiloxane.

Specific examples of aromatic diamines include p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenylether, 4-aminophenyl-4-aminobenzoate, 4,4'-diaminoazobenzene, 3,5-diaminobenzoic acid, 1,5-bis(4-aminophenoxy)pentane, 1,2-bis(4-aminophenoxy)ethane, 1,3-bis(4-aminophenoxy)propane, 1,6-bis(4-aminophenoxy)hexane, bis[2-(4-aminophenyl)ethyl]hexanedioic acid, 1,4-bis-(4-aminophenyl)-piperazine, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2 -bis(4-aminophenyl)hexafluoropropane, 4,4'-(phenylenediisopropylidene)bisaniline, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-[4,4'-propane-1,3-diylbis(piperidine-1,4-diyl)]dianiline, 4,4'-diaminobenzanilide, 4,4'-diaminostilbene, 1, Main chain diamines such as 4-bis(4-aminophenyl)-piperazine, bis[2-(4-aminophenyl)ethyl]hexanedioic acid, 4,4'-diaminodiphenethyl urea, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 1,4-bis(4-aminophenoxy)benzene, and 4,4'-bis(4-aminophenoxy)biphenyl;
Dodecanoxy-2,4-diaminobenzene, pentadecanoxy-2,4-diaminobenzene, hexadecanoxy-2,4-diaminobenzene, octadecanoxy-2,4-diaminobenzene, pentadecanoxy-2,5-diaminobenzene, octadecanoxy-2,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, 3,5-di Cholestanyl aminobenzoate, cholestenyl 3,5-diaminobenzoate, lanostannyl 3,5-diaminobenzoate, 3,6-bis(4-aminobenzoyloxy)cholestane, 3,6-bis(4-aminophenoxy)cholestane, 4-(4'-trifluoromethoxybenzoyloxy)cyclohexyl-3,5-diaminobenzoate, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-butylcyclohexane, 3,5-diaminobenzoic acid=5ξ-cholestan-3-yl, compounds represented by the following formula (E-1):
(In formula (E-1), X ^I and X ^II each independently represent a single bond, —O—, *-COO—, or *-OCO— (wherein “*” represents a bond to the diaminophenyl group). R ^I represents an alkanediyl group having 1 to 3 carbon atoms. R ^II represents a single bond or an alkanediyl group having 1 to 3 carbon atoms. R ^III represents an alkyl group, alkoxy group, fluoroalkyl group, or fluoroalkoxy group having 1 to 20 carbon atoms. a represents 0 or 1. b represents an integer of 0 to 3. c represents an integer of 0 to 2. d represents 0 or 1, provided that 1≦a+b+c≦3.)
and side chain diamines such as compounds represented by the following formula:

Examples of the compound represented by formula (E-1) include compounds represented by the following formulas (E-1-1) to (E-1-4).

Specific examples of diaminoorganosiloxanes include 1,3-bis(3-aminopropyl)-tetramethyldisiloxane. In addition to the above, other diamines that can be used include the diamine compounds described in JP-A-2010-97188.

Polyamic acid (P) can be obtained by reacting a tetracarboxylic dianhydride with a diamine compound, optionally with a molecular weight modifier. The ratio of the tetracarboxylic dianhydride and diamine compound used in the synthesis reaction of polyamic acid (P) is preferably such that 0.2 to 2 equivalents of acid anhydride groups in the tetracarboxylic dianhydride are used per equivalent of amino groups in the diamine compound.

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

The synthesis reaction of polyamic acid (P) is preferably carried out in an organic solvent. The reaction temperature is preferably -20°C to 150°C, and the reaction time is preferably 0.1 to 24 hours.

Examples of organic solvents used in the reaction include aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons. Particularly preferred organic solvents include one or more selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide, m-cresol, xylenol, and halogenated phenols. Alternatively, a mixture of one or more of these with another organic solvent (e.g., butyl cellosolve, diethylene glycol diethyl ether, etc.) is preferred. The amount of organic solvent (a) used is preferably an amount such that the combined amount (b) of tetracarboxylic dianhydride and diamine is 0.1 to 50% by mass relative to the total amount (a + b) of the reaction solution.

In this manner, a reaction solution containing dissolved polyamic acid (P) is obtained. This reaction solution may be used directly to prepare a liquid crystal aligning agent, or the polyamic acid (P) contained in the reaction solution may be isolated and then used to prepare a liquid crystal aligning agent, or the isolated polyamic acid (P) may be purified and then used to prepare a liquid crystal aligning agent. When polyamic acid (P) is to be dehydrated and cyclized to form a polyimide, the reaction solution may be used directly to the dehydration and cyclization reaction, or the polyamic acid (P) contained in the reaction solution may be isolated and then used to prepare a dehydration and cyclization reaction, or the isolated polyamic acid (P) may be purified and then used to prepare a dehydration and cyclization reaction. Isolation and purification of polyamic acid (P) can be performed according to known methods.

(Polyamic acid ester)
The polyamic acid ester as the polymer (P) (hereinafter also referred to as "polyamic acid ester (P)") can be obtained, for example, by [I] a method of reacting the polyamic acid (P) obtained by the above synthesis reaction with an esterifying agent, [II] a method of reacting a tetracarboxylic acid diester with a diamine compound, or [III] a method of reacting a tetracarboxylic acid diester dihalide with a diamine compound.

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

Esterifying agents used in method [I] include hydroxyl group-containing compounds, acetal compounds, halides, epoxy group-containing compounds, etc. Specific examples of these include: hydroxyl group-containing compounds such as alcohols (e.g., methanol, ethanol, and propanol), and phenols (e.g., phenol and cresol); acetal compounds such as N,N-dimethylformamide diethyl acetal and N,N-diethylformamide diethyl acetal; halides such as methyl bromide, ethyl bromide, stearyl bromide, methyl chloride, stearyl chloride, and 1,1,1-trifluoro-2-iodoethane; and epoxy group-containing compounds such as propylene oxide.

The tetracarboxylic acid diester used in method [II] can be obtained, for example, by ring-opening the tetracarboxylic acid dianhydride exemplified in the description of the synthesis of polyamic acid (P) using an alcohol such as methanol or ethanol. The tetracarboxylic acid derivative used in method [II] may be a tetracarboxylic acid diester alone, or may be used in combination with a tetracarboxylic acid dianhydride.

The tetracarboxylic acid diester dihalide used in method [III] can be obtained, for example, by reacting the tetracarboxylic acid diester obtained as described above with a suitable chlorinating agent such as thionyl chloride. The tetracarboxylic acid derivative used in method [III] may be a tetracarboxylic acid diester dihalide alone, or may be used in combination with a tetracarboxylic acid dianhydride.

The polyamic acid ester (P) contained in the liquid crystal aligning agent may have only an amic acid ester structure, or may be a partially esterified product in which an amic acid structure and an amic acid ester structure coexist. The reaction solution in which the polyamic acid ester (P) is dissolved may be used directly to prepare the liquid crystal aligning agent, or the polyamic acid ester (P) contained in the reaction solution may be isolated and then used to prepare the liquid crystal aligning agent, or the isolated polyamic acid ester (P) may be purified and then used to prepare the liquid crystal aligning agent. The polyamic acid ester (P) can be isolated and purified according to known methods.

(Polyimide)
The polyimide as the polymer (P) (hereinafter also referred to as "polyimide (P)") can be obtained, for example, by dehydrating and ring-closing the polyamic acid (P) synthesized as described above to form an imidized product.

Polyimide (P) may be a fully imidized product in which all of the amic acid structures contained in its precursor polyamic acid (P) have been dehydrated and cyclized, or a partially imidized product in which only a portion of the amic acid structures have been dehydrated and cyclized, resulting in both amic acid structures and imide ring structures. The polyimide (P) preferably has an imidization rate of 20% or more, and more preferably 30 to 99%. This imidization rate is the ratio, expressed as a percentage, of the number of imide ring structures to the total number of amic acid structures and imide ring structures in the polyimide (P). Some of the imide rings may be isoimide rings.

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

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

In this way, a reaction solution containing polyimide (P) is obtained. This reaction solution may be used directly to prepare a liquid crystal aligning agent, or the dehydrating agent and dehydration ring-closing catalyst may be removed from the reaction solution before use in the preparation of a liquid crystal aligning agent. The polyimide (P) may be isolated and then used in the preparation of a liquid crystal aligning agent, or the isolated polyimide (P) may be purified and then used in the preparation of a liquid crystal aligning agent. These purification operations can be performed according to known methods. Alternatively, polyimide (P) can also be obtained by imidizing polyamic acid ester (P).

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

The polystyrene-equivalent weight-average molecular weight (Mw) of polymer (P) measured by gel permeation chromatography (GPC) is preferably 1,000 to 500,000, and more preferably 2,000 to 300,000. Furthermore, the molecular weight distribution (Mw/Mn) of polymer (P), expressed as the ratio of Mw to the polystyrene-equivalent number-average molecular weight (Mn) measured by GPC, is preferably 8 or less, and more preferably 7 or less. Having Mw and Mw/Mn of polymer (P) within the above ranges ensures good liquid crystal alignment in liquid crystal devices.

The content of polymer (P) in the liquid crystal aligning agent is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, based on the total amount of solids contained in the liquid crystal aligning agent (i.e., the total mass of the components of the liquid crystal aligning agent other than the solvent).

[Other ingredients]
The liquid crystal aligning agent of the present disclosure may further contain components other than the polymer (P) (hereinafter also referred to as "other components"). Examples of the other components include a polymer different from the polymer (P) (hereinafter also referred to as "polymer (Q)"), a crosslinking agent, a solvent, etc.

Polymer (Q)
The polymer (Q) is a polymer that does not have a structural unit derived from a diamine having a partial structure represented by the above formula (1). The main skeleton of the polymer (Q) is not particularly limited. Examples of the polymer (Q) include polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane, polyester, polyenamine, polyurea, polyamide, polyamideimide, polybenzoxazole precursor, polybenzoxazole, cellulose derivative, polyacetal, and addition polymer. Examples of the addition polymer include (meth)acrylic polymers, styrene polymers, maleimide polymers, (meth)acrylic-styrene copolymers, (meth)acrylic-maleimide copolymers, (meth)acrylic-styrene-maleimide copolymers, and styrene-maleimide copolymers.

Of these, polymer (Q) is preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane, and addition polymer, since it exhibits good liquid crystal alignment properties when used in combination with polymer (P).

When polymer (Q) is contained in the liquid crystal aligning agent, the content of polymer (Q) is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more, based on the total amount of polymer (P) and polymer (Q). Furthermore, the content of polymer (Q) is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less, based on the total amount of polymer (P) and polymer (Q).

When imparting liquid crystal alignment ability to an organic film formed using a liquid crystal alignment agent using a photoalignment method, it is preferable that at least a portion of polymer (P) and polymer (Q) be polymers having photoalignment groups. A photoalignment group is a functional group that can impart anisotropy to a film through a photoreaction such as a photoisomerization reaction, photodimerization reaction, photo-Fries rearrangement reaction, or photodecomposition reaction due to light irradiation.

Specific examples of photoalignable groups include azobenzene-containing groups containing azobenzene or a derivative thereof as the basic skeleton; cinnamic acid structure-containing groups containing cinnamic acid or a derivative thereof (cinnamic acid structure) as the basic skeleton; chalcone-containing groups containing chalcone or a derivative thereof as the basic skeleton; benzophenone-containing groups containing benzophenone or a derivative thereof as the basic skeleton; coumarin-containing groups containing coumarin or a derivative thereof as the basic skeleton; cyclobutane-containing groups containing cyclobutane or a derivative thereof as the basic skeleton; stilbene-containing groups containing stilbene or a derivative thereof as the basic skeleton; and phenylbenzoate-containing groups containing phenylbenzoate or a derivative thereof as the basic skeleton. Of these, the photoalignable group is preferably at least one selected from the group consisting of azobenzene-containing groups, cinnamic acid structure-containing groups, chalcone-containing groups, stilbene-containing groups, cyclobutane-containing structures, and phenylbenzoate-containing groups. Cinnamic acid structure-containing groups and cyclobutane-containing structures are preferred due to their high photosensitivity and ease of incorporation into polymers.

There are no particular limitations on the method for synthesizing a polymer having a photoalignment group. A polymer having a photoalignment group can be obtained, for example, by (1) polymerization using a monomer having a photoalignment group; or (2) synthesis of a polymer having a first functional group (e.g., an epoxy group) on its side chain, followed by reaction of the resulting first functional group-containing polymer with a reactive compound having a photoalignment group and a second functional group (e.g., a carboxy group) that forms a bond with the first functional group.

Crosslinking Agent The liquid crystal aligning agent of the present disclosure preferably contains a crosslinking agent. By further containing a crosslinking agent in the liquid crystal aligning agent of the present disclosure, the film density of the liquid crystal alignment film can be increased, and the effect of suppressing the generation of impurities originating from the liquid crystal alignment film can be further enhanced. Furthermore, by suppressing the generation of impurities in the element, the intrusion of impurities into the liquid crystal can be minimized.

As the crosslinking agent, in terms of high reactivity with the polymer (P) or high reactivity between crosslinking agents, compounds having at least one group selected from the group consisting of a group represented by ^-OY2 (wherein ^Y2 is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a monovalent leaving group), an amino group, a protected amino group, a mercapto group, a protected mercapto group, a group represented by -Si( ^OR21 ) _k ( ^R22 ) _3-k (wherein ^R21 and ^R22 are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, k is an integer from 1 to 3, and when k is 2 or 3, multiple ^R21s are the same or different, and when k is 1, multiple ^R22s are the same or different), an oxiranyl group, an oxetanyl group, and a polymerizable carbon-carbon double bond group (hereinafter also referred to as a "specific crosslinkable group") can be preferably used.

The monovalent leaving group represented by ^Y2 is preferably a group that is eliminated by heat or light and replaced with a hydrogen atom. Specific examples of the leaving group represented by ^Y2 include ether-based leaving groups such as alkyl groups having 7 or less carbon atoms, benzyl groups, and p-methoxybenzyl groups; acetal-based leaving groups such as methoxymethyl groups, ethoxyethyl groups, and 2-tetrahydropyranyl groups; acyl-based leaving groups such as acetyl groups and benzoyl groups; allyl-based leaving groups such as allyl groups and methallyl groups; and silyl ether-based leaving groups such as trimethylsilyl groups, triethylsilyl groups, and tert-butyldimethylsilyl groups. From the viewpoint of achieving both ease of leaving and storage stability, the leaving group represented by ^Y2 is preferably an ether-based leaving group, an acetal-based leaving group, or an acetyl group, more preferably an alkyl group having 4 to 7 carbon atoms, a 2-tetrahydropyranyl group, a methoxymethyl group, a 1-ethoxyethyl group, or an acetyl group, and even more preferably a 2-tetrahydropyranyl group, a methoxymethyl group, a 1-ethoxyethyl group, or an acetyl group. Furthermore, ^Y2 is particularly preferably a hydrogen atom, an alkyl group having 7 or less carbon atoms, an acetyl group, a 2-tetrahydropyranyl group, a methoxymethyl group, or a 1-ethoxyethyl group, among the above.

In terms of high reactivity with the polymer (P) (particularly the benzene ring moiety), the group represented by ^-OY2 is preferably bonded to a carbon atom, more preferably bonded to an alkanediyl group, and further preferably a group constituting a part of a methylol group or a hydroxyalkylamide group.

In the protected amino group, examples of the leaving group bonded to the nitrogen atom include carbamate-based leaving groups, amide-based leaving groups, imide-based leaving groups, and sulfonamide-based leaving groups. Of these, carbamate-based leaving groups are preferred because of their high thermal releasability. Specific examples include tert-butoxycarbonyl, benzyloxycarbonyl, 1,1-dimethyl-2-haloethyloxycarbonyl, allyloxycarbonyl, 2-(trimethylsilyl)ethoxycarbonyl, and 9-fluorenylmethyloxycarbonyl (F-moc) groups. Of these, the tert-butoxycarbonyl (Boc) group is particularly preferred because of its excellent thermal releasability and the ability to reduce the amount of deprotected moieties remaining in the film.
In the protected mercapto group, examples of the leaving group bonded to the sulfur atom include the same groups as those exemplified as ^Y2 .

When the specific crosslinkable group possessed by the crosslinking agent is an amino group or a protected amino group, the crosslinking agent is preferably a chain compound. Furthermore, when the crosslinking agent has a protected primary amino group as the protected amino group, the protected amino group may be a primary amino group in which only one of the two hydrogen atoms has been replaced with a leaving group, or a group in which both hydrogen atoms have been replaced with leaving groups.

In the group represented by —Si(OR ²¹ ) _k (R ²² ) _3-k , examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by R ²¹ or R ²² include a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms. From the viewpoint of photoreactivity, R ²¹ is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and even more preferably a methyl group or an ethyl group. R ²² is preferably an alkyl group having 1 to 10 carbon atoms or a substituted or unsubstituted phenyl group, and more preferably a methyl group, an ethyl group, or a phenyl group.
From the viewpoint of increasing the crosslinking reactivity, k is preferably 2 or 3, and more preferably 3.

When the crosslinking agent has a polymerizable carbon-carbon double bond group, the polymerizable carbon-carbon double bond group is preferably an unsaturated bond contained in a group represented by any of the following formulae (g1-1) to (g1-10), in that it has high crosslinking reactivity and can provide a liquid crystal alignment film with more excellent electrical properties.
(In formulas (g1-1) to (g1-10), "*" represents a bond.)

When the crosslinking agent has a polymerizable carbon-carbon double bond group, it preferably has a group represented by formula (g1-1) to formula (g1-7) above. Of these, it is more preferable that the crosslinking agent has a group represented by formula (g1-1) to formula (g1-4) above, in terms of high crosslinking reactivity and ease of introducing functional groups.

The number of specific crosslinkable groups possessed by the crosslinking agent is not particularly limited. From the viewpoint of increasing the crosslinking reactivity between the polymer (P) and the crosslinking agent and obtaining a liquid crystal alignment film with higher film density, the number of specific crosslinkable groups possessed by the crosslinking agent per molecule is preferably 2 or more, and more preferably 2 to 10. The crosslinking agent is preferably a compound different from the polymer (non-polymer). The molecular weight of the crosslinking agent is, for example, 1,200 or less, preferably 1,000 or less, and more preferably 800 or less.

Specific examples of the crosslinking agent include compounds having a group represented by ^—OY2 , such as compounds represented by the following formulas (5A-1) to (5A-34):
As the compound having a mercapto group or a protected mercapto group, compounds represented by the following formulas (5B-1) to (5B-6) are mentioned:
As the compound having an amino group or a protected amino group, compounds represented by the following formulae (5C-1) to (5C-13) may be used:
Examples of compounds having a group represented by —Si(OR ²¹ ) _r (R ²² ) _3-r include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, and vinyltriethoxysilane;
Examples of compounds having an oxiranyl group or an oxetanyl group include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, triglycidyl isocyanurate, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, N,N,N',N'-tetraglycidyl-m-oxy Silylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenyl ether, N,N-diglycidyl-benzylamine, N,N-diglycidyl-aminomethylcyclohexane, N,N-diglycidyl-cyclohexylamine, epoxidation reaction products of pentaerythritol tetraallyl ether with hydrogen peroxide, compounds having an oxiranyl group among those exemplified as compounds having a group represented by —Si(OR ²¹ ) _r (R ²² ) _3-r , etc.;
Examples of the compound having a polymerizable carbon-carbon double bond group include ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, pentaerythritol tri(meth)acrylate, and compounds represented by the following formulas (5D-1) to (5D-7).

From the viewpoint of crosslinking reactivity with the polymer (P), the crosslinking agent is preferably at least one selected from the group consisting of a compound having a group represented by ^-OY2 , a compound having an amino group or a protected amino group, a compound having a mercapto group or a protected mercapto group, an oxiranyl group, an oxetanyl group, and a compound having a polymerizable carbon-carbon double bond group, and more preferably at least one selected from the group consisting of a compound having a group represented by ^-OY2 , a compound having an amino group, a compound having a protected amino group, a compound having an oxiranyl group, and a compound having an oxetanyl group.

When a crosslinking agent is contained in the liquid crystal aligning agent of the present disclosure, the content of the crosslinking agent is preferably 0.5 parts by mass or more relative to 100 parts by mass of the total amount of polymer components contained in the liquid crystal aligning agent (i.e., the total amount of polymer (P) and polymer (Q)) from the viewpoints of increasing the film density of the liquid crystal alignment film and improving the durability of the liquid crystal alignment film. From the above viewpoints, the content of the crosslinking agent is more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, relative to 100 parts by mass of the total amount of polymer components. Furthermore, from the viewpoints of obtaining a liquid crystal element with good liquid crystal alignment properties and electrical properties, and improving the storage stability of the liquid crystal aligning agent, the content of the crosslinking agent is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, relative to 100 parts by mass of the total amount of polymer components.

Solvent The liquid crystal aligning agent of the present disclosure is preferably prepared as a liquid composition in which the polymer (P) and components used as needed are dispersed or dissolved in a suitable solvent.

Examples of the organic solvent used include N-methyl-2-pyrrolidone, γ-butyrolactone, γ-butyrolactam, N,N-dimethylformamide, N,N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisopentyl ether, ethylene carbonate, and propylene carbonate.

Other components include, in addition to those mentioned above, antioxidants, metal chelate compounds, curing accelerators, surfactants, fillers, dispersants, photosensitizers, acid generators, base generators, and radical generators. The blending ratio of each of these components can be selected appropriately depending on the compound, as long as it does not impair the effects of the present disclosure.

The solids concentration in the liquid crystal aligning agent (the proportion of the total mass of the liquid crystal aligning agent's components other than the solvent to the total mass of the liquid crystal aligning agent) is selected appropriately taking into consideration viscosity, volatility, etc., but is preferably in the range of 1 to 10% by mass. That is, the liquid crystal aligning agent is applied to the substrate surface as described below, and preferably heated to form a coating film that is a liquid crystal alignment film or a coating film that will become a liquid crystal alignment film. In this case, if the solids concentration is 1% by mass or more, the coating film can be sufficiently thick, and a good liquid crystal alignment film tends to be easily obtained. If the solids concentration is 10% by mass or less, the coating film thickness does not become too large, and an increase in the viscosity of the liquid crystal aligning agent can be suppressed, tending to improve applicability.

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

While it is unclear why using a liquid crystal alignment agent containing polymer (P) improves idling resistance during inkjet coating and also results in liquid crystal elements with excellent reliability and impurity resistance, the following is speculated. First, with regard to the reliability and impurity resistance of liquid crystal elements, introducing a nitrogen-containing heterocycle (base component) into the side chain of the polymer suppresses the depolymerization reaction of the amic acid moiety in polymer (P). As a result, it is thought that the durability of the liquid crystal alignment film is improved and the generation of impurities from the alignment film is suppressed. Furthermore, the suppression of the generation of impurities from the alignment film also suppresses the intrusion of impurities into the liquid crystal layer. Furthermore, because polymer (P) has a nitrogen-containing heterocycle in the side chain, impurities from the insulating film and other materials are adsorbed by the liquid crystal alignment film and retained within the film, which is thought to enhance the effect of suppressing impurities from entering the liquid crystal layer. As a result, it is thought that the deterioration of the reliability and voltage holding ratio of liquid crystal elements due to the generation of impurities was sufficiently suppressed.

On the other hand, when a nitrogen-containing heterocycle is introduced into the side chain of the polymer, intermolecular pseudo-crosslinking due to acid-base interactions is more likely to occur, making the polymer component in the liquid crystal aligning agent more likely to precipitate, which is thought to result in reduced idling resistance during inkjet coating. In this regard, the structural unit derived from a diamine having a nitrogen-containing heterocycle introduced into the polymer (P) has a monovalent organic group having 1 to 6 carbon atoms in at least one of R ¹ and R ² in the above formula (1), which is thought to reduce the degree of rotational freedom of the main chain skeleton (in other words, the mobility of the molecular chain). This makes it less likely for intermolecular pseudo-crosslinking due to acid-base interactions to occur, and as a result, it is thought that a liquid crystal aligning agent that is less likely to dry out or absorb moisture even during idling can be obtained. However, the above speculation does not limit the present disclosure.

<Liquid crystal alignment film and liquid crystal element>
The liquid crystal alignment film of the present disclosure is formed using the liquid crystal alignment agent prepared as described above. Furthermore, the liquid crystal element of the present disclosure has a liquid crystal alignment film formed using the liquid crystal alignment agent described above. The operation mode of the liquid crystal in the liquid crystal element is not particularly limited, and various modes, such as TN type, STN type, VA type (including VA-MVA type, VA-PVA type, etc.), IPS (In-Plane Switching) type, FFS (Fringe Field Switching) type, OCB (Optically Compensated Bend) type, and PSA (Polymer Sustained Alignment) type, can be applied. The liquid crystal element can be manufactured, for example, by a method including the following steps 1 to 3. In step 1, the substrate used varies depending on the desired operation mode. Steps 2 and 3 are common to all operation modes.

<Step 1: Formation of coating film>
First, a liquid crystal alignment agent is applied to a substrate, and the coated surface is preferably heated to form a coating film on the substrate. Examples of substrates that can be used include glass such as float glass and soda glass; and transparent substrates made of resins such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, and poly(alicyclic olefin). When manufacturing TN-type, STN-type, or VA-type liquid crystal devices, two substrates each having a patterned transparent conductive film are used. On the other hand, when manufacturing IPS-type or FFS-type liquid crystal devices, one substrate has a comb-shaped patterned electrode and one counter substrate has no electrode. Examples of transparent conductive films that can be used include a NESA film (registered trademark of PPG, USA) made of tin oxide (SnO ₂ ), an ITO film made of indium oxide-tin oxide (In ₂ O ₃ -SnO ₂ ), and the like. The liquid crystal aligning agent is applied to the substrate surface preferably by offset printing, flexographic printing, spin coating, roll coating, or inkjet printing. The liquid crystal aligning agent of the present disclosure has excellent idling resistance during inkjet coating, and is therefore suitable as a liquid crystal aligning agent for inkjet coating.

After the liquid crystal alignment agent is applied, preheating (pre-baking) is preferably performed to prevent dripping of the applied liquid crystal alignment agent. The pre-baking temperature is preferably 30 to 200°C, and the pre-baking time is preferably 0.25 to 10 minutes. A baking (post-baking) step is then performed to remove the solvent from the applied liquid crystal alignment agent. The baking temperature (post-baking temperature) at this time is preferably 80 to 250°C, more preferably 80 to 200°C. The post-baking time is preferably 5 to 200 minutes. The thickness of the film formed in this manner is preferably 0.001 to 1 μm.

<Step 2: Alignment Treatment>
When producing a TN-type, STN-type, IPS-type, or FFS-type liquid crystal device, the coating film formed in step 1 is subjected to a treatment (alignment treatment) to impart liquid crystal alignment ability. This imparts the alignment ability of liquid crystal molecules to the coating film, resulting in a liquid crystal alignment film. Examples of alignment treatments that can be used include a rubbing treatment in which the coating film formed on the substrate is rubbed in a certain direction with a roll wrapped with a cloth made of fibers such as nylon, rayon, or cotton, and a photoalignment treatment in which the coating film formed on the substrate is irradiated with light to impart liquid crystal alignment ability to the coating film. On the other hand, when producing a vertical alignment (VA)-type liquid crystal device, the coating film formed in step 1 can be used as is as a liquid crystal alignment film. Furthermore, the coating film may be subjected to an alignment treatment to further enhance the liquid crystal alignment ability. Liquid crystal alignment films suitable for vertical alignment-type liquid crystal devices are also suitable for PSA-type liquid crystal devices.

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

Examples of light sources used include low-pressure mercury lamps, high-pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonance lamps, xenon lamps, and excimer lasers. The radiation dose on the substrate surface is preferably 400 to 50,000 J/ ^m2 , and more preferably 1,000 to 20,000 J/ ^m2 . After light irradiation to impart alignment ability, the substrate surface may be washed with, for example, water, an organic solvent (e.g., methanol, isopropyl alcohol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, etc.), or a mixture thereof, or the substrate may be heated.

<Step 3: Construction of liquid crystal cell>
Two substrates each having a liquid crystal alignment film formed thereon are prepared as described above, and a liquid crystal cell is fabricated between the two substrates, with the liquid crystal disposed adjacent to the liquid crystal alignment film. Examples of methods for fabricating a liquid crystal cell include: placing two substrates facing each other with a gap between them so that the liquid crystal alignment films face each other; bonding the peripheries of the two substrates together with a sealant; injecting liquid crystal into the cell gap surrounded by the substrate surfaces and the sealant; and sealing the injection hole; and an ODF method. Examples of sealants that can be used include epoxy resins containing a curing agent and aluminum oxide spheres as spacers. Examples of liquid crystals include nematic liquid crystals and smectic liquid crystals, with nematic liquid crystals being preferred. In the PSA mode, a liquid crystal cell is constructed by disposing a photopolymerizable compound together with the liquid crystal between two substrates. After the liquid crystal cell is constructed, the liquid crystal cell is irradiated with light while a voltage is applied between the conductive films of the pair of substrates.

When a PSA type liquid crystal element is manufactured, the liquid crystal element can be manufactured by a method including the following steps [1] to [3].
[1] A step of applying the liquid crystal aligning agent of the present disclosure onto each conductive film of a pair of substrates having a conductive film to form a coating film.
[2] A step of constructing a liquid crystal cell by arranging a pair of substrates coated with a liquid crystal alignment agent so that the coating films face each other with a liquid crystal layer sandwiched therebetween.
[3] A step of irradiating the liquid crystal cell with light while a voltage is applied between the conductive films.

Specifically, a liquid crystal cell is constructed in the same manner as steps 1 to 3 above, except that a photopolymerizable compound is injected or dropped along with the liquid crystal between a pair of substrates having a conductive film. Any conventionally known compound can be used as the photopolymerizable compound. A polyfunctional (meth)acrylic compound is preferred.

After the liquid crystal cell is constructed, the liquid crystal cell is irradiated with light while a voltage is applied between the conductive films of the pair of substrates (step [3]). The voltage applied here can be, for example, 5 to 50 V DC or AC. The light to be irradiated can be, for example, ultraviolet light containing light with a wavelength of 150 to 800 nm and visible light. Of these, ultraviolet light containing light with a wavelength of 300 to 400 nm is preferred. The light source for the irradiation light can be, for example, a low-pressure mercury lamp, a high-pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, or an excimer laser. The light irradiation dose is preferably 1,000 to 200,000 J/ ^m² , and more preferably 1,000 to 100,000 J/ ^m² .

For each mode of liquid crystal cell, a polarizing plate is then attached to the outer surface of the liquid crystal cell as needed to create a liquid crystal element. Examples of polarizing plates include polarizing plates in which a polarizing film called an "H film," made by stretching and aligning polyvinyl alcohol and absorbing iodine, is sandwiched between cellulose acetate protective films, or polarizing plates made of the H film itself.

The liquid crystal element of the present disclosure can be effectively applied to a variety of applications. Specifically, it can be used in various display devices such as watches, portable game consoles, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, LCD televisions, and information displays, as well as in light control films and retardation films.

The present disclosure described above includes the following aspects [1] to [10].
[1] A liquid crystal aligning agent comprising a polymer (P) which is at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide and which contains a structural unit derived from a diamine represented by the above formula (1).
[2] The liquid crystal aligning agent according to [1], wherein R ¹ in the formula (1) is a monovalent organic group having 1 to 6 carbon atoms.
[3] The liquid crystal aligning agent according to [1] or [2], wherein at least one of R ¹ and R ² in the formula (1) is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a phenyl group, -COR ⁵ or -NR ⁶ R ⁷ (wherein R ⁵ , R ⁶ and R ⁷ are each independently an alkyl group having 1 to 3 carbon atoms).
[4] The liquid crystal aligning agent according to any one of [1] to [3], wherein R ¹ in the above formula (1) is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a phenyl group, -COR ⁵ or -NR ⁶ R ⁷ (wherein R ⁵ , R ⁶ and R ⁷ are each independently an alkyl group having 1 to 3 carbon atoms), and R ² in the above formula (1) is a hydrogen atom.
[5] The liquid crystal aligning agent according to any one of [1] to [4], wherein the monovalent group having a nitrogen-containing heterocyclic structure has a nitrogen-containing aromatic heterocyclic ring.
[6] The liquid crystal aligning agent according to any one of [1] to [5], further comprising a crosslinking agent.
[7] A liquid crystal alignment film formed using the liquid crystal aligning agent according to any one of [1] to [6].
[8] A liquid crystal element comprising the liquid crystal alignment film according to [7].
[9] A polymer which is a polyamic acid, a polyamic acid ester, or a polyimide and contains a structural unit derived from a diamine represented by the above formula (1).
[10] A diamine represented by the above formula (1).

The following provides a more detailed explanation using examples, but the present invention is not limited to these examples.

In the following examples, the weight average molecular weight (Mw), number average molecular weight (Mn), imidization ratio of polyimide, and epoxy equivalent of polyorganosiloxane were measured by the following methods.
<Weight average molecular weight (Mw) and number average molecular weight (Mn)>
Mw and Mn were measured by gel permeation chromatography (GPC) under the following conditions. The molecular weight distribution (Mw/Mn) was calculated from the obtained Mw and Mn.
Apparatus: Showa Denko "GPC-101"
GPC column: Shimadzu GLC's "GPC-KF-801", "GPC-KF-802", "GPC-KF-803" and "GPC-KF-804" combined Mobile phase: Tetrahydrofuran (THF)
Column temperature: 40°C
Flow rate: 1.0 mL/min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Detector: Differential refractometer Standard material: Monodisperse polystyrene <imidization rate of polyimide>
The polyimide solution was poured into pure water, and the resulting precipitate was thoroughly dried under reduced pressure at room temperature. The precipitate was then dissolved in deuterated dimethyl sulfoxide and subjected to ^1H -NMR measurement at room temperature using tetramethylsilane as a reference substance. The imidization rate [%] was calculated from the obtained ^1H -NMR spectrum using the following formula (1).
Imidization rate [%] = (1 - (β ¹ / (β ² × α))) × 100 (1)
(In formula (1), ^β1 is the peak area derived from the proton of the NH group appearing at a chemical shift of around 10 ppm, ^β2 is the peak area derived from other protons, and α is the ratio of the number of other protons to one proton of the NH group in the polymer precursor (polyamic acid).)

<Epoxy equivalent of polyorganosiloxane>
Measurement was performed in accordance with the "hydrochloric acid - methyl ethyl ketone method" of JIS C2105.

The abbreviations for the compounds used in the following examples are shown below. For convenience, "compound represented by formula (X)" may be referred to simply as "compound (X)." In the examples and comparative examples, "parts" and "%" are by mass unless otherwise specified.

・Tetracarboxylic acid dianhydride

・Diamine compounds

Siloxane monomer and carboxylic acid

Monomers with polymerizable carbon-carbon unsaturated bonds

・Additives

<Synthesis of Polymer>
1. Synthesis of polyamic acid [Synthesis Example 1]
70 parts by mole of compound (CA-2) and 30 parts by mole of compound (CA-1) as tetracarboxylic dianhydrides, and 30 parts by mole of compound (DA-1), 20 parts by mole of compound (DB-2), 20 parts by mole of compound (DB-4), and 30 parts by mole of compound (DB-8) as diamine compounds were dissolved in N-methyl-2-pyrrolidone (NMP), and the mixture was reacted at 60°C for 6 hours to obtain a solution containing 20% by mass of polyamic acid (referred to as polymer (PAA-1)).

[Synthesis Examples 2 to 19]
Polyamic acids (referred to as polymers (PAA-2) to (PAA-19)) were obtained by the same procedure as in Synthesis Example 1, except that the types and amounts of the tetracarboxylic dianhydrides and diamine compounds used were changed as shown in Table 1. In Table 1, the numerical values for the tetracarboxylic dianhydrides represent the ratio (molar ratio) of each compound relative to 100 parts by mole of the total amount of the tetracarboxylic dianhydrides used in the synthesis of the polyamic acid. The numerical values for the diamine compounds represent the ratio (molar ratio) of each compound relative to 100 parts by mole of the total amount of the diamine compounds used in the synthesis of the polyamic acid.

2. Synthesis of polyimide [Synthesis Example 20]
100 parts by mole of compound (CA-2) as a tetracarboxylic dianhydride, and 30 parts by mole of compound (DA-1), 20 parts by mole of compound (DB-2), 20 parts by mole of compound (DB-4), and 30 parts by mole of compound (DB-8) as diamine compounds were dissolved in NMP and reacted at 60°C for 6 hours to obtain a solution containing 20% by mass of polyamic acid. Next, NMP was added to the obtained polyamic acid solution to obtain a solution with a polyamic acid concentration of 10% by mass, and pyridine and acetic anhydride were added, followed by a dehydration ring-closing reaction at 80°C for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with fresh NMP to obtain a solution containing 15% by mass of polyimide (referred to as polymer (PI-1)) with an imidization rate of approximately 62%.

[Synthesis Examples 21 to 28]
Polyimides (referred to as polymers (PI-2) to (PI-9)) were obtained in the same manner as in Synthesis Example 20, except that the types and amounts of the tetracarboxylic dianhydrides and diamine compounds used were changed as shown in Table 1.

3. Synthesis of polyorganosiloxane [Synthesis Example 29]
A reaction vessel equipped with a stirrer, thermometer, dropping funnel, and reflux condenser was charged with 100.0 g of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (a compound represented by the above formula (S-1)), 500 g of methyl isobutyl ketone, and 10.0 g of triethylamine, and mixed at room temperature. Next, 100 g of deionized water was added dropwise from the dropping funnel over 30 minutes, and then the mixture was stirred under reflux at 80 ° C. for 6 hours. After completion of the reaction, the organic layer was removed and washed with a 0.2% by mass aqueous ammonium nitrate solution until the water after washing was neutral. The solvent and water were then distilled off under reduced pressure to obtain an epoxy group-containing polyorganosiloxane (ESSQ-1) as a viscous, transparent liquid.
When polyorganosiloxane (ESSQ-1) was analyzed by ^1H -NMR, a peak due to the epoxy group was observed at a chemical shift (δ) of approximately 3.2 ppm, confirming that no side reactions of the epoxy group occurred during the reaction. The weight-average molecular weight Mw of the resulting polyorganosiloxane (ESSQ-1) was 3,500, and the epoxy equivalent was 180 g/mol.
In a 200 mL three-neck flask, 10.0 g of polyorganosiloxane (ESSQ-1), 30.28 g of methyl isobutyl ketone as a solvent, the compound represented by the above formula (S-2) and the compound represented by the above formula (S-3) as modified components (carboxylic acids), the total amount of epoxy groups in polyorganosiloxane (ESSQ-1) was equivalent to 20 mol% and 10 mol%, respectively, and 0.10 g of UCAT 18X (trade name, manufactured by San-Apro Co., Ltd.) was charged as a catalyst and the reaction was carried out under stirring at 100 ° C. for 48 hours. After completion of the reaction, ethyl acetate was added to the reaction mixture, and the resulting solution was washed three times with water, the organic layer was dried using magnesium sulfate, and the solvent was then distilled off to obtain a polyorganosiloxane containing an orienting group (this is referred to as polymer (PSQ-1)). The weight average molecular weight (Mw) of the resulting polymer was 8,000.

4. Synthesis of styrene-maleimide copolymer [Synthesis Example 30]
Under nitrogen, a 100 mL two-neck flask was charged with 18.7 mmol of compound (MA-2), 18.7 mmol of compound (MA-4), 10.6 mmol of compound (MA-6), and 5.3 mmol of compound (MA-7) as monomers having a polymerizable carbon-carbon unsaturated bond, 0.98 g of 2,2'-azobis(2,4-dimethylvaleronitrile) as a radical polymerization initiator, and 50 mL of N-methyl-2-pyrrolidone (NMP) as a solvent, and the mixture was polymerized at 70°C for 6 hours. After reprecipitation in methanol, the precipitate was filtered and dried in vacuum at room temperature for 8 hours to obtain a styrene-maleimide copolymer (referred to as polymer (MI-1)). The weight average molecular weight (Mw) measured in terms of polystyrene by GPC was 35,000, and the molecular weight distribution (Mw/Mn) was 2.

[Synthesis Example 31]
A styrene-maleimide copolymer (referred to as polymer (MI-2)) was obtained in the same manner as in Synthesis Example 30, except that the types and amounts of the polymerization monomers used were changed as shown in Table 2.

<Evaluation>
<Preparation and Evaluation of Liquid Crystal Alignment Agent>
[Example 1: PSA type liquid crystal display element]
1. Preparation of Liquid Crystal Alignment Agent A solution containing 100 parts by mass of the polymer (PAA-1) obtained in Synthesis Example 1 was diluted with NMP, γ-butyrolactone (GBL), ethylene glycol monobutyl ether (BC), diacetone alcohol (DAA), and diethylene glycol diethyl ether (DEDG), and 7 parts by mass of compound (AD-3) was added to obtain a solution with a solvent composition of NMP:GBL:BC:DAA:DEDG=30:30:20:10:10 (mass ratio) and a solids concentration of 4.0% by mass. This solution was filtered through a filter with a pore size of 0.2 μm to prepare a liquid crystal alignment agent (AL-1).

2. Preparation of Liquid Crystal Composition Liquid crystal composition LC1 was obtained by adding 0.3% by mass of a photopolymerizable compound represented by the following formula (L-1) to 10 g of a nematic liquid crystal (negative liquid crystal manufactured by Merck, MLC-6608) and mixing them.

3. Preparation of PSA-type liquid crystal cell The liquid crystal aligning agent (AL-1) prepared above was applied to each electrode surface of two glass substrates each having an ITO electrode patterned into a slit shape and partitioned into multiple regions as shown in Figure 1, using a liquid crystal alignment film printer (manufactured by Nissha Printing Co., Ltd.). Next, the substrate was heated (pre-baked) on a hot plate at 80°C for 1 minute to remove the solvent, and then heated (post-baked) on a hot plate at 150°C for 10 minutes to form a coating film with an average film thickness of 0.06 μm.
This coating film was subjected to ultrasonic cleaning in ultrapure water for 1 minute, and then dried in a clean oven at 100°C for 10 minutes to obtain a substrate having a coating film that would become a liquid crystal alignment film. This procedure was repeated to obtain a pair (two substrates) having a coating film. The electrode pattern used was the same type as the electrode pattern in the PSA mode.
Next, an epoxy resin adhesive containing 5.5 μm diameter aluminum oxide spheres was applied to the outer edges of each of the coated substrates, and the substrates were then placed together with the coated surfaces facing each other and pressed together, allowing the adhesive to cure. The liquid crystal composition LC1 prepared above was then filled between the pair of substrates through the liquid crystal injection port, which was then sealed with an acrylic photocurable adhesive. The resulting liquid crystal cell was then exposed to light at a dose of 100,000 J/ ^m² while a voltage was applied between the conductive films.

4. Evaluation of Reliability The reliability of the liquid crystal element was evaluated using the liquid crystal cell (liquid crystal cell after light irradiation) produced in the above 3. The evaluation was performed as follows.
First, a voltage of 5 V was applied to the liquid crystal cell for 60 microseconds over a span of 167 milliseconds, and the voltage holding ratio (VHR1) was measured 167 milliseconds after the application was stopped. The liquid crystal cell was then placed in an 80°C oven under LED lamp irradiation for 200 hours, and then allowed to cool naturally to room temperature. After cooling, a voltage of 5 V was applied to the liquid crystal cell for 60 microseconds over a span of 167 milliseconds, and the voltage holding ratio (VHR2) was measured 167 milliseconds after the application was stopped. The measurement device used was a "VHR-1" manufactured by Toyo Corporation. The rate of change in VHR (ΔVHR) at this time was calculated using the following formula (I):
ΔVHR[%]=(VHR1-VHR2)/(VHR1)×100...(I)
The reliability of the liquid crystal element was evaluated based on the ΔVHR calculated as above. The evaluation was as follows: if ΔVHR was less than 1.0%, the reliability was "very good (◎)", if it was 1.0% or more and less than 2.5%, the reliability was "good (○)", and if it was 2.5% or more, the reliability was "poor (×)". As a result, in this example, ΔVHR = 0.8%, and the reliability was "very good (◎)".

5. Idling Resistance During Inkjet (IJ) Coating An idling resistance test was carried out as follows using an inkjet device (manufactured by Shibaura Mechatronics Corporation) equipped with a head having a total of 256 ejection holes adjusted so that the ejection amount per dot was 50 pL.
First, the liquid crystal alignment agent (AL-1) was filled into the inkjet device, and dummy ejection was performed in a state where the liquid crystal alignment agent (AL-1) could be ejected without any problems from all 256 ejection holes. The head was then left as is for a certain period of time. An ejection test was performed on a substrate that had been subjected to a water-repellent surface treatment to prevent droplets from wetting and spreading after the head was left standing, and the number of droplets that were ejected normally was counted visually. If 90% or more of the droplets were ejected normally out of the total number of ejection holes, the idling resistance of the head was judged to pass; otherwise, it was judged to fail. The test was started three hours after the head was left standing, and was continued every three hours thereafter until the idling resistance failed. If the idling resistance time passed the test for 15 hours or more, the idling resistance was judged to be "good (○)," if it was 9 hours or more but less than 15 hours, the idling resistance was judged to be "fair (△)," and if it was less than 9 hours, the idling resistance was judged to be "poor (×)." As a result, in this example, the idling resistance was judged to be "good (○)."

6. Impurity Resistance (1) Preparation of Insulating Film-Forming Composition A flask equipped with a condenser and a stirrer was charged with 7 parts by weight of 2,2'-azobis(2,4-dimethylvaleronitrile), 200 parts by weight of propylene glycol monomethyl ether acetate, 15 parts by weight of methacrylic acid, 30 parts by weight of glycidyl methacrylate, 20 parts by weight of styrene, 5 parts by weight of 2-hydroxyethyl acrylate, and 30 parts by weight of isobornyl acrylate. After purging with nitrogen, gentle stirring was initiated. The reaction solution was heated to 62°C and maintained at this temperature for 5 hours to obtain a polymer solution containing acrylic copolymer (R-1). The resulting polymer solution was added dropwise to 900 parts by weight of hexane to precipitate the acrylic copolymer (R-1). The precipitated acrylic copolymer (R-1) was separated, and 150 parts by weight of propylene glycol monomethyl ethyl acetate was added. The mixture was heated to 40°C and distilled under reduced pressure to obtain a polymer solution containing acrylic copolymer (R-1). The solids concentration of the obtained polymer solution containing the acrylic copolymer (R-1) was 30% by mass, and as a result of GPC analysis, the area of unreacted monomer and polymerization initiator was 2.3%, and the weight average molecular weight (Mw) was 12,800.
For an amount equivalent to 100 parts by mass (solid content) of the acrylic copolymer (R-1), 25 parts by mass of a condensate of 4,4'-[1-[4-[1-[4-hydroxyphenyl]-1-methylethyl]phenyl]ethylidene]bisphenol (1.0 mol) and 1,2-naphthoquinone diazide-5-sulfonic acid chloride (2.0 mol) was used as a photosensitizer, and a mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate ("KAYARAD" manufactured by Nippon Kayaku Co., Ltd.) was used as a polymerizable compound. A mixture of 5 parts by mass of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (Kyowanol M manufactured by Kyowa Hakko Kirin Co., Ltd.) as a film-forming aid, 10 parts by mass of SH28PA (manufactured by Dow Corning Toray Co., Ltd.) as a leveling agent, and diethylene glycol ethyl methyl ether was added to the mixture to give a solids concentration of 18% by mass. The mixture was then dissolved and filtered through a membrane filter with a pore size of 0.2 μm to prepare a composition for forming an insulating film (RD-1).

(2) Preparation of a substrate with an insulating film The insulating film-forming composition (RD-1) was applied to a glass substrate using a spin coater, and then pre-baked on a hot plate at 90°C for 2 minutes. Next, the entire substrate was irradiated with light at 300 mJ/ ^cm2 using a proximity exposure machine (Canon's "MA-1200" (ghi-ray mixed)), and then heated (post-baked) in an oven at 230°C for 30 minutes to harden, forming an insulating film with a film thickness of 3 μm on the glass substrate.

(3) Production of liquid crystal cell for impurity tolerance evaluation A liquid crystal alignment agent (AL-1) was applied to each of the electrode formation surface of a substrate provided with comb-tooth-patterned ITO electrodes and the insulating film formation surface of a substrate provided with an insulating film, using a spinner, and heated (pre-baked) on a hot plate at 80°C for 1 minute. Thereafter, the substrate was heated (post-baked) at 230°C for 1 hour in an oven whose interior had been replaced with nitrogen, to produce a pair (two substrates) each having a liquid crystal alignment film with a film thickness of 0.1 μm.
An epoxy resin adhesive containing 3.5 μm diameter aluminum oxide spheres was applied by screen printing to the outer periphery of the surface of the insulating substrate bearing the liquid crystal alignment film. The pair of substrates were then pressed together with the liquid crystal alignment film surfaces facing each other, and the adhesive was thermally cured at 150°C for 1 hour. Next, liquid crystal composition LC1 was filled into the gap between the substrates through the liquid crystal injection port, which was then sealed with an epoxy adhesive. Furthermore, to eliminate flow alignment during liquid crystal injection, the sample was heated to 130°C and then slowly cooled to room temperature to produce a liquid crystal cell. Because substrate preparation is simple, the liquid crystal cells used to evaluate impurity tolerance were prepared using electrode substrates for IPS-type liquid crystal cells.

(4) Evaluation of Impurity Resistance The liquid crystal cell for evaluating impurity resistance manufactured in 6.(3) above was placed in an oven at 60°C, and then the voltage holding ratio (VHR) was measured under conditions of 1 V and 1670 milliseconds using a VHR measuring device "VHR-1" manufactured by Toyo Corporation. A VHR of more than 60% was rated "good (○)", a VHR of 60% or less and 45% or more was rated "fair (△)", and a VHR of less than 45% was rated "poor (×)". As a result, the electrical characteristics of this example were rated "good (○)".

[Examples 2 to 4, 6 to 11, 13 to 23 and Comparative Examples 1 to 10]
The same operation as in Example 1 was performed except that the composition of the liquid crystal alignment agent was changed as shown in Table 3. Liquid crystal alignment agents (AL-2) to (AL-4), (AL-6) to (AL-11), (AL-13) to (AL-23), and (AR-1) to (AR-10) were prepared. Furthermore, using the obtained liquid crystal alignment agent, liquid crystal cells were produced in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 3. In Table 3, the values in the mass ratio column represent the blending ratio (parts by mass) of the solid content of each compound (polymer, additive) relative to 100 parts by mass of the total amount of the polymer components used in the preparation of the liquid crystal alignment agent. The values in parentheses in the reliability (ΔVHR) column represent the value of ΔVHR calculated by the above formula (I).

[Example 5: Optical VA type liquid crystal display element]
1. Preparation of Liquid Crystal Alignment Agent The same operation as in Example 1 was carried out except that the composition of the liquid crystal alignment agent was changed as shown in Table 3, to prepare a liquid crystal alignment agent (AL-5).
2. Evaluation In Example 1, the substrate used to prepare the liquid crystal cell was a glass substrate with a transparent electrode made of an ITO film, a liquid crystal alignment agent (AL-5) was used, and the post-baked coating surface was irradiated with 1,000 J/ ^m² of polarized ultraviolet light containing a 313 nm emission line using an Hg-Xe lamp and a Glan-Taylor prism from a direction tilted 40° from the substrate normal to impart liquid crystal alignment ability, and a negative liquid crystal (MLC-6608, manufactured by Merck) was used instead of liquid crystal composition LC1. An optical VA-type liquid crystal cell was prepared by the same operation as in Example 1, and reliability was evaluated in the same manner as in Example 1. In addition, using the liquid crystal alignment agent (AL-5), idling resistance and impurity resistance were evaluated in the same manner as in Example 1. In the evaluation of impurity resistance, a liquid crystal cell for evaluating impurity resistance was prepared by the same operation as when preparing the optical VA-type liquid crystal cell, except that the same substrates as in Example 1 (substrates having an electrode substrate and an insulating film for an IPS-type liquid crystal cell) were used instead of the pair of glass substrates with transparent electrodes made of ITO films, and the impurity resistance was evaluated by the same operation as in Example 1. The evaluation results are shown in Table 3.

[Example 12]
A liquid crystal aligning agent (AL-12) was prepared in the same manner as in Example 1, except that the composition of the liquid crystal aligning agent was changed as shown in Table 3. In addition, various evaluations were carried out in the same manner as in Example 5 using the obtained liquid crystal aligning agent (AL-12). The results are shown in Table 3.

[Example 24: Optical horizontal type liquid crystal display element]
1. Preparation of Liquid Crystal Alignment Agent The same operation as in Example 1 was carried out except that the composition of the liquid crystal alignment agent was changed as shown in Table 3, to prepare a liquid crystal alignment agent (AL-24).

2. Preparation of an Optically Directed Liquid Crystal Cell The liquid crystal alignment agent (AL-24) prepared above was applied to each transparent electrode surface of a pair of glass substrates (two substrates) with transparent electrodes made of ITO films using a spinner and heated (pre-baked) on a hot plate at 80°C for 1 minute. This was then heated (post-baked) for 30 minutes in a nitrogen-purged 230°C oven to form a coating film with an average thickness of 0.1 μm. The resulting coating film was subjected to a photo-alignment treatment by irradiating it with 1,000 J/ ^m² of linearly polarized ultraviolet light containing a 254 nm emission line from an Hg-Xe lamp in the direction normal to the substrate. The irradiation dose was measured using an actinometer measuring at a wavelength of 254 nm. The photo-aligned coating film was then heat-treated in a clean oven at 230°C for 30 minutes to form a liquid crystal alignment film.
Next, for one of the pair of substrates on which the liquid crystal alignment film was formed, an epoxy resin adhesive containing 3.5 μm diameter aluminum oxide spheres was applied by screen printing to the outer edge of the surface bearing the liquid crystal alignment film. The substrates were then superimposed and pressed together so that the projection directions of the polarization axes on the substrate surfaces during light irradiation were antiparallel, and the adhesive was thermally cured at 150°C for 1 hour. Next, negative liquid crystal (MLC-6608, manufactured by Merck) was injected between the pair of substrates through the liquid crystal injection port, which was then sealed with an epoxy adhesive. Furthermore, to eliminate flow alignment during liquid crystal injection, the substrate was heated at 120°C and then slowly cooled to room temperature to obtain a liquid crystal cell.

3. Evaluation Reliability was evaluated in the same manner as in Example 1 using the optically-oriented horizontal liquid crystal cell prepared in 2 above. Furthermore, idling resistance and impurity resistance were evaluated in the same manner as in Example 1 using a liquid crystal aligning agent (AL-24). For the evaluation of impurity resistance, a liquid crystal cell for evaluating impurity resistance was prepared by the same procedure as in preparing the optically-oriented horizontal liquid crystal cell, except that the same substrates as in Example 1 (substrates comprising an electrode substrate and an insulating film for an IPS-type liquid crystal cell) were used instead of the pair of substrates consisting of the first and second substrates. The impurity resistance was evaluated by the same procedure as in Example 1. The evaluation results are shown in Table 3.

[Example 25: Rubbed horizontal type liquid crystal display element]
1. Preparation of Liquid Crystal Alignment Agent The same operation as in Example 1 was carried out except that the composition of the liquid crystal alignment agent was changed as shown in Table 3, to prepare a liquid crystal alignment agent (AL-25).

2. Preparation of Rubbed Horizontal Liquid Crystal Cell The liquid crystal alignment agent (AL-25) prepared above was applied to each transparent electrode surface of a pair (two) of glass substrates with transparent electrodes made of ITO films using a spinner and heated (pre-baked) on a hot plate at 80 ° C for 1 minute. The substrate was then heated (post-baked) at 230 ° C for 1 hour in an oven whose interior had been replaced with nitrogen to form a coating film with a thickness of 0.1 μm. This coating film was subjected to a rubbing treatment using a rubbing machine equipped with a roll wrapped around a rayon cloth at a roll rotation speed of 400 rpm, a stage movement speed of 3 cm/sec, and a pile indentation length of 0.1 mm. The substrate was then ultrasonically cleaned in ultrapure water for 1 minute and then dried in a clean oven at 100 ° C for 10 minutes to obtain a substrate with a liquid crystal alignment film.
Next, an epoxy resin adhesive containing 3.5 μm diameter aluminum oxide spheres was applied by screen printing to the outer periphery of the surface of one of the substrates bearing the liquid crystal alignment film, and the substrates were then superimposed with the liquid crystal alignment film surfaces facing each other and pressed together, followed by thermal curing of the adhesive at 150°C for 1 hour. Next, a negative liquid crystal (MLC-6608, manufactured by Merck) was filled into the gap between the substrates through the liquid crystal injection port, which was then sealed with an epoxy adhesive. Furthermore, to eliminate flow alignment during liquid crystal injection, the substrate was heated at 130°C and then slowly cooled to room temperature, yielding a liquid crystal cell.

3. Evaluation Using the rubbed horizontal liquid crystal cell prepared in 2. above, reliability was evaluated in the same manner as in Example 1. Furthermore, using a liquid crystal aligning agent (AL-25), idling resistance and impurity resistance were evaluated in the same manner as in Example 1. In addition, in the evaluation of impurity resistance, a liquid crystal cell for evaluating impurity resistance was prepared by carrying out the same operations as in the preparation of the rubbed horizontal liquid crystal cell, except that the same substrates as in Example 1 (substrates comprising an electrode substrate and an insulating film for an IPS-type liquid crystal cell) were used instead of the pair of glass substrates with transparent electrodes made of ITO films, and impurity resistance was evaluated by the same operations as in Example 1. The evaluation results are shown in Table 3.

As shown in Table 3, in Examples 1 to 25, the reliability, idling resistance, and impurity resistance were all evaluated as "very good (◎),""good(○)," or "fair (△)." Furthermore, even in the examples (Examples 8 to 17 and 21 to 23) where the evaluation result included "fair (△)," only one of the three items (reliability, idling resistance, and impurity resistance) was evaluated as "fair (△)," indicating a good balance of various characteristics.
In contrast, in Comparative Examples 1 to 10, one or more of the evaluations of reliability, idling resistance, and impurity resistance were "poor (×)", or multiple evaluations were "fair (△)", and the samples were inferior to Examples 1 to 25.

Claims (10)

A liquid crystal aligning agent comprising a polymer (P) which is at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide and which contains a structural unit derived from a diamine represented by the following formula (1):
(In formula (1), ^R1 and ^R2 are each independently a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms, provided that at least one of ^R1 and ^R2 is a monovalent organic group having 1 to 6 carbon atoms. ^R3 and ^R4 are each independently a hydrogen atom or a monovalent group having a nitrogen-containing heterocyclic structure, provided that at least one of ^R3 and ^R4 is a monovalent group having a nitrogen-containing heterocyclic structure.) 2. The liquid crystal aligning agent according to claim 1, wherein R ¹ in the formula (1) is a monovalent organic group having 1 to 6 carbon atoms. The liquid crystal aligning agent according to claim 1, wherein at least one of R ¹ and R ² in the above formula (1) is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a phenyl group, -COR ⁵ or -NR ⁶ R ⁷ (wherein R ⁵ , R ⁶ and R ⁷ are each independently an alkyl group having 1 to 3 carbon atoms). R ¹ in the above formula (1) is an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a phenyl group, -COR ⁵ or -NR ⁶ R ⁷ (wherein R ⁵ , R ⁶ and R ⁷ are each independently an alkyl group having 1 to 3 carbon atoms),
The liquid crystal aligning agent according to claim 3, wherein ^R2 in the formula (1) is a hydrogen atom. The liquid crystal aligning agent according to claim 1, wherein the monovalent group having a nitrogen-containing heterocyclic structure has a nitrogen-containing aromatic heterocyclic ring. The liquid crystal aligning agent according to claim 1, further containing a crosslinking agent. A liquid crystal alignment film formed using the liquid crystal alignment agent according to any one of claims 1 to 6. A liquid crystal element comprising the liquid crystal alignment film according to claim 7. A polymer which is a polyamic acid, a polyamic acid ester or a polyimide and which contains a structural unit derived from a diamine represented by the following formula (1):
(In formula (1), ^R1 and ^R2 are each independently a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms, provided that at least one of ^R1 and ^R2 is a monovalent organic group having 1 to 6 carbon atoms. ^R3 and ^R4 are each independently a hydrogen atom or a monovalent group having a nitrogen-containing heterocyclic structure, provided that at least one of ^R3 and ^R4 is a monovalent group having a nitrogen-containing heterocyclic structure.) A diamine represented by the following formula (1):
(In formula (1), ^R1 and ^R2 are each independently a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms, provided that at least one of ^R1 and ^R2 is a monovalent organic group having 1 to 6 carbon atoms. ^R3 and ^R4 are each independently a hydrogen atom or a monovalent group having a nitrogen-containing heterocyclic structure, provided that at least one of ^R3 and ^R4 is a monovalent group having a nitrogen-containing heterocyclic structure.)