TWI908834B - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal element - Google Patents

Abstract

This invention provides a liquid crystal alignment agent that can form a liquid crystal alignment film with excellent adhesion to sealants and substrates and can obtain a liquid crystal element that is not prone to image retention. A liquid crystal alignment agent comprises: a polymer [A] having a partial structure represented by formula (1); a polymer [B] having a partial structure represented by formula (2); and a polymer [C] having a partial structure X in the main chain. Partial structure X: a structure represented by -( _CH2 ) _a- or _a structure in which any methylene group in the structure represented by -( _CH2 )a- is replaced by a group such as ^-NR7- . In formula (1), ^R1 is a protecting group. In formula (2), ^A1 and ^A4 are each independently a divalent aromatic cycloalloy. ^R2 and ^R3 are each independently a hydrogen atom or a monovalent organic group. ^B1 is a single bond, ^-NR4- , -O-, or a divalent aromatic heterocyclic group.

Description

Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal element

This invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal element.

As liquid crystal materials for liquid crystal elements, negative liquid crystals are used in liquid crystal elements driven by vertical alignment (VA) or multi-domain vertical alignment (MVA) methods, while positive liquid crystals are used in liquid crystal elements driven by twisted nematic (TN) or in-plane switching (IPS) and fringe field switching (FFS) methods. Furthermore, in recent years, to achieve further miniaturization of liquid crystal elements, the use of negative liquid crystals in IPS or FFS driving methods has also been proposed (see, for example, Patent 1).

In recent years, liquid crystal elements have been widely used in a wide range of applications, from relatively large display devices such as LCD TVs or information displays to small display devices such as smartphones. With the increasing versatility of these liquid crystal elements, there is a growing demand for higher quality. Therefore, it has been proposed to incorporate a polymer with a nitrogen-containing meta-arylene structure into the liquid crystal alignment agent, thereby obtaining a liquid crystal alignment film with low resistance and high transparency, and a liquid crystal element with less burn-in (direct current (DC) retention) caused by stored charge (see, for example, Patent 2).

In touchscreen display devices such as smartphones and tablet PCs, efforts are being made to achieve narrow bezels while further increasing the operating area of the touchscreen and miniaturizing the display device. One known method for achieving narrow bezels involves forming a liquid crystal alignment film across the entire substrate surface, then applying a sealant to the liquid crystal alignment film and bonding the substrates together (see, for example, Patent 3). [Prior Art Documents] [Patent Documents]

[Patent Document 1] International Publication No. 2016/152928 [Patent Document 2] International Publication No. 2019/093037 [Patent Document 3] Japanese Patent Application Publication No. 2013-109154

[Problem to be Solved by the Invention] When a sealant is applied to the liquid crystal alignment film to achieve narrower bezels in liquid crystal elements, there is a tendency for the liquid crystal alignment film to peel off from the substrate at the sealant area. This raises concerns about reduced reliability of the liquid crystal element.

Furthermore, in cases where the aim is to reduce image retention in liquid crystal elements by incorporating meta-aryl structures into polymers, as described in Patent 2, the liquid crystal alignment film becomes hard and brittle due to the presence of numerous aromatic rings derived from the meta-aryl structure. This raises concerns about reduced adhesion between the liquid crystal alignment film and the substrate (especially at the spacer sites). On the other hand, it is difficult to simultaneously satisfy multiple properties such as image retention reduction, adhesion to the substrate, and adhesion to the sealant, leaving room for further improvement in liquid crystal alignment agents.

This invention addresses the aforementioned problems, with the primary objective of providing a liquid crystal alignment agent capable of forming a liquid crystal alignment film with excellent adhesion to sealants and substrates, and yielding a liquid crystal element that is less prone to image retention. [Technical Means for Solving the Problem]

The inventors have diligently researched and discovered that the problem can be solved by using various polymers with different structures, thus completing this invention. Specifically, this invention provides the following means.

<1> A liquid crystal alignment agent comprising: polymer [A] having a partial structure represented by formula (1) below and not having a partial structure represented by formula (2) below; polymer [B] having a partial structure represented by formula (2) below; and polymer [C] having a partial structure X in a main chain and not having a partial structure represented by formula (1) below and a partial structure represented by formula (2) below. Partial structure X: The structure represented by -( _CH2 ) _a- (where a is an integer from 2 to 20), or the structure represented by -( _CH2 ) _a- in which any methylene group is substituted with at least one group selected from the group consisting of ^-NR7- , -O-, -COO-, ^-NR7 -CO-, ^-NR7 -COO-, ^-NR8 -CO- ^NR9- and nitrogen-containing non-aromatic heterocyclic groups (where ^R7 is a hydrogen atom or alkyl group; ^R8 and ^R9 are each independently a hydrogen atom or alkyl group, or represent a ring structure formed by ^R8 and ^R9 combined with the nitrogen atom bonded to ^R8 , the nitrogen atom bonded to ^R9 , and -CO-; ^-NR7- , -O-, -COO-, ^-NR7 -CO-, ^-NR7 -COO-, ^-NR8- , -CO- ^NR9- , and nitrogen-containing non-aromatic heterocyclic groups are not adjacent to each other. [Chem. 1] (In equation (1), ^R1 is the protection base; "*" indicates the bond) [Chemistry 2] (In formula (2), ^A1 and ^A4 are each independently a divalent aromatic cyclic group; ^R2 and ^R3 are each independently a hydrogen atom or a monovalent organic group; ^B1 is a single bond, ^-NR4- , -O- or a divalent aromatic heterocyclic group; ^R4 is a hydrogen atom or a monovalent organic group; when ^B1 is a single bond, ^A2 is a divalent aromatic cyclic group, and ^A3 is a single bond or a divalent aromatic cyclic group; when ^B1 is a divalent aromatic heterocyclic group, ^A2 and ^A3 are each independently a single bond or a divalent aromatic cyclic group; when ^B1 is ^-NR4- or -O-, ^A2 and ^A3 are each independently a divalent aromatic cyclic group, or represent A The aromatic rings of ^A and ^B are linked by single bonds or chains and together with -NR ^4- or -O- form a nitrogen- or oxygen-containing fused ring structure; "*" indicates a bond.

<2> A liquid crystal alignment film formed from the liquid crystal alignment agent of <1>. <3> A liquid crystal alignment film comprising: a polymer having a structural unit having a partial structure represented by formula (1A) in a portion different from the polymerizing base, and a polymer not having the partial structure represented by formula (2); a polymer having the partial structure represented by formula (2); and a polymer having the partial structure X in the main chain and not having the partial structure represented by formula (2). [Chemical 3] (In formula (1A), "*" represents a bond) <4> A liquid crystal element comprising the liquid crystal alignment film of <2> or <3>. [Effects of the Invention]

According to the liquid crystal alignment agent of the present invention, a liquid crystal alignment film with excellent adhesion to the sealant and the substrate can be formed, and a liquid crystal element that is not prone to image retention can be obtained. In particular, the liquid crystal alignment agent of the present invention can improve the adhesion between the substrate and the liquid crystal alignment film at the spacer configuration portion.

The liquid crystal alignment agent disclosed herein contains three polymers with different monomer compositions: polymer [A], polymer [B], and polymer [C]. The components contained in the liquid crystal alignment agent disclosed herein, as well as other components that may be arbitrarily formulated as needed, will be described below.

Furthermore, in this specification, the term "alkane" encompasses chain-like hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons. "Chain-like hydrocarbons" refer to linear and branched hydrocarbons that consist solely of chain structures and do not contain ring structures in their main chain. These chains can be saturated or unsaturated. "Alicyclic hydrocarbons" refer to hydrocarbons that contain only alicyclic hydrocarbon structures as ring structures and do not contain aromatic ring structures. This does not necessarily mean that the hydrocarbons consist solely of alicyclic hydrocarbon structures; it also includes groups that have chain structures in a portion of their structure. "Aromatic hydrocarbons" refer to hydrocarbons that contain aromatic ring structures as ring structures. It is not necessary to consist solely of aromatic ring structures; a portion of it may also contain chain structures or alicyclic hydrocarbon structures. "Aromatic ring" means that it includes aromatic hydrocarbon rings and aromatic heterocycles. The term "structural unit" refers to the unit that mainly constitutes the main chain structure, and must contain at least two units in the main chain structure. Regarding each component and each compound, unless otherwise specified, one type may be used alone, or two or more types may be used in combination. The term "protecting group" refers to a group in which a highly reactive characteristic group (-NH- in formula (1) below) is temporarily replaced with an inert functional group.

<Polymer [A]> Polymer [A] is a polymer having a partial structure represented by the following formula (1). [Chemistry 4] (In equation (1), ^R1 is the protection base; "*" indicates the bond.)

In formula (1), the protecting group of ^R1 is preferably a monovalent group that is desorbed by heat, such as: carbamate-based protecting groups, amide-based protecting groups, amide-imine-based protecting groups, sulfonamide-based protecting groups, etc. Among these, ^R1 is preferably a carbamate-based protecting group in terms of high desorbability caused by heat. Specific examples of protecting groups include: tert-butoxycarbonyl (Boc group), benzyloxycarbonyl, 1,1-dimethyl-2-halogenated ethoxycarbonyl, allyloxycarbonyl (Alloc group), 2-(trimethylsilyl)ethoxycarbonyl, 9-fluorenylmethoxycarbonyl (F-moc group), etc. Of these, tert-butoxycarbonyl is particularly preferred in terms of its excellent heat-induced detachability, which improves the sealing performance of the sealant and reduces the amount of residue in the membrane after detachment from the protected part.

Furthermore, in equation (1), one of the two "*" symbols can be bonded to a hydrogen atom. That is, one of the two "*" symbols in equation (1) is bonded to a hydrogen atom, and the other is bonded to a carbon atom. Alternatively, both of the two "*" symbols can be bonded to a carbon atom.

The polymer [A] is preferably having the partial structure represented by the formula (1) and the partial structure Y described below. In the case that the polymer [A] also has the partial structure Y, in addition to DC image retention, the generation of AC image retention caused by the alignment direction of the liquid crystal deviating from the initial alignment can be suppressed, which is preferred in this respect. Partial structure Y: The structure represented by -( _CH2 ) _b- (where b is an integer from 2 to 20), or the structure represented by -( _CH2 ) _b- in which any methylene group is substituted by at least one of the groups consisting of ^-NR10- , -O-, -COO-, ^-NR10 -CO-, ^-NR10 -COO-, ^-NR10 -CO- ^NR11- and nitrogen-containing non-aromatic heterocyclic groups (where ^R10 and ^R11 are each independently a hydrogen atom or a monovalent organic group; in partial structure Y, ^-NR10- , -O-, -COO-, ^-NR10 -CO-, ^-NR10 -COO-, -NR10-CO- ^NR11- and nitrogen- ^containing non-aromatic heterocyclic groups are not adjacent to each other).

Regarding the improvement effect of reducing AC retention in liquid crystal elements, b in partial structure Y is preferably 2 or more, and more preferably includes a linear alkyl diester with 2 or more carbon atoms in partial structure Y. Furthermore, from the viewpoint of suppressing the reduction of film strength, b is preferably 12 or less, and more preferably 10 or less. When ^R10 and ^R11 are monovalent organic groups, the monovalent organic group is preferably a monovalent hydrocarbon group or a protecting group having 1 to 10 carbon atoms. The monovalent hydrocarbon group is preferably an alkyl or phenyl group having 1 to 3 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms. Examples and preferred examples of the protecting group can be found in the description of ^R1 . In this description, ^R10 and ^R11 are preferably hydrogen atoms, alkyl groups having 1 to 3 carbon atoms, or tert-butoxycarbonyl groups. Examples of nitrogen-containing non-aromatic heterocyclic groups include guanidine-1,4-diyl and guanidine-1,4-diyl.

Polymer [A] may have the partial structure represented by formula (1) independently of partial structure Y, or may have the partial structure represented by formula (1) in partial structure Y. When partial structure Y has the partial structure represented by formula (1), polymer [A] has the following structure as partial structure Y: a structure in which any methylene group in the structure represented by -( _CH2 ) _b- is substituted with at least one group selected from the group consisting of ^-NR10- , ^-NR10 -CO-, ^-NR10 -COO- and ^-NR10 -CO- ^NR11- , and is a structure in which at least one of ^R10 and ^R11 is a protecting group. In the case where the partial structure Y is a structure with a protective group, by using a monomer having the partial structure Y in the manufacture of polymer [A], it is preferable to simultaneously improve the sealant adhesion and reduce AC retention. In terms of improving the effect of reducing AC retention of liquid crystal elements, polymer [A] is preferably having the partial structure Y in the main chain. Polymer [A] does not have the partial structure represented by the following formula (2) of polymer [B].

Furthermore, in this specification, the phrase "other polymers do not have" a portion of the structure possessed by at least one of the polymers contained in the liquid crystal alignment agent (hereinafter referred to as "specific structure") is used to imply that other polymers may possess the specific structure to the extent that it does not impair the effects of the invention. In the absence of a specific structure in other polymers, the content of the specific structure in the other polymers is preferably 1 mol% or less, more preferably 0.5 mol% or less, and even more preferably 0.1 mol% or less (the same applies to polymers [B] and [C]).

The main chain of polymer [A] is not particularly limited, but in terms of forming a liquid crystal alignment film with high affinity and mechanical strength and high reliability with respect to the ease of incorporating the partial structure represented by the formula (1) into the polymer, polymer [A] is preferably selected from at least one of the group consisting of polyamide, polyamide ester and polyimide.

The method for manufacturing polymer [A] is not particularly limited and can be carried out according to conventional organic chemistry methods. Specifically, examples include: a method of polymerization using a monomer having a partial structure represented by formula (1); a method of introducing the partial structure represented by formula (1) into the polymer end by reacting the polymer end with a compound having a partial structure represented by formula (1). Among these, in terms of further improving the adhesion between the liquid crystal alignment film and the sealant, it is preferable to manufacture polymer [A] by polymerization using a monomer having a partial structure represented by formula (1). That is, polymer [A] is preferably a polymer having structural units derived from a monomer having a partial structure represented by formula (1).

Furthermore, the term "main chain" refers to the portion of the polymer containing the longest atomic chain, known as the "trunk." This "trunk" portion may contain ring structures. For example, "having a specific structure in the main chain" means that the specific structure constitutes part of the main chain. The term "side chain" refers to a portion that branches off from the polymer's "trunk."

(Polyamide) When polymer [A] is polyamide, in terms of the high degree of freedom in selecting monomers and the ease of incorporating the partial structure represented by formula (1), the polyamide (hereinafter also referred to as "polyamide [A]") is preferably manufactured by reacting a tetracarboxylic dianhydride with a diamine compound containing a diamine (hereinafter also referred to as "specific diamine (A)") having the partial structure represented by formula (1).

Tetracarboxylic dianhydrides Tetracarboxylic dianhydrides used in the synthesis of polyacrylic acid [A] include, for example, aliphatic tetracarboxylic dianhydrides, cycloaliphatic tetracarboxylic dianhydrides, aromatic tetracarboxylic dianhydrides, etc. Specific examples of these include aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride and ethylenediaminetetraacetic acid dianhydride; and alicyclic tetracarboxylic dianhydrides such as 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxylated cyclopentylacetic acid dianhydride, 5-(2,5-dioxotetrahydrofuran-3-yl)-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, and 5-(2,5-dioxotetrahydrofuran-3-yl)-8-methyl-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione. [2-c]furan-1,3-dione, 2,4,6,8-tetracarboxylic bicyclic [3.3.0]octane-2:4,6:8-dianhydride, cyclopentanetetracarboxylic dianhydride, cyclohexanetetracarboxylic dianhydride, etc.; aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-(hexafluoroisopropyl)diphthalic anhydride, ethylene glycol dimethacrylate anhydride, 4,4'-(hexafluoroisopropyl)diphthalic anhydride, 4,4'-carbonyldiphthalic anhydride, etc. In addition, the tetracarboxylic dianhydride described in Japanese Patent Application Publication No. 2010-97188 may also be used.

Regarding the achievement of liquid crystal alignment films exhibiting high solvent solubility and low afterimage characteristics, the tetracarboxylic dianhydride used in the synthesis of polyacrylic acid [A] is preferably an alicyclic tetracarboxylic dianhydride. The proportion of alicyclic tetracarboxylic dianhydride used is preferably 20 mol% or more, more preferably 40 mol% or more, and even more preferably 50 mol% or more, relative to the total amount of tetracarboxylic dianhydride used in the synthesis of polyacrylic acid [A].

The specific diamine (A) used in the synthesis of the diamine polymer [A] is preferably a compound represented by the following formula (1-1). [Chemistry 5] (In formula (1-1), ^A7 and ^A8 are each independently divalent aromatic cyclic groups; ^Y1 is a divalent organic group; r is 0 or 1; wherein, when r is 1, at least any one of ^A7 , ^A8 and ^Y1 has the partial structure represented by formula (1); when r is 0, ^A7 has the partial structure represented by formula (1))

In formula (1-1), divalent aromatic hydrocarbons and divalent aromatic heterocyclic groups can be listed as the divalent aromatic cyclic groups of ^A7 and ^A8 . ^A7 and ^A8 may also have substituents in the aromatic ring portion. As such substituents, alkyl groups having 1 to 5 carbon atoms, halogen atoms, monovalent groups having a partial structure represented by formula (1), etc., can be listed.

As preferred examples of ^A7 and ^A8 , divalent aromatic hydrocarbons may include groups formed by removing any two hydrogen atoms bonded to a carbon atom of a ring forming a benzene, naphthyl, or anthracene ring; divalent aromatic heterocyclic groups may include groups formed by removing any two hydrogen atoms bonded to a carbon atom of a ring forming a pyridine, pyrimidine, darazine, or pyrazine ring. Of these, ^A7 and ^A8 are preferably substituted or unsubstituted pentenylphenyl, pentenylbiphenyl, or pentenylpyridinyl groups.

As divalent organic groups of ^Y1 , the following can be listed: the structure represented by -( _CH2 ) _b- , the structure in which any methylene group in the structure represented by -( _CH2 ) _b- is substituted by at least one group selected from the group consisting of ^-NR10- , -O-, ^-COO- , ^-NR10 -CO-, ^-NR10 -COO-, ^-NR10 -CO- ^NR11- and nitrogen-containing non- ^aromatic heterocyclic groups, ^-NR10- , -NR10-CO-, ^-NR10 -CO- ^NR11- , etc. Of these, ^Y1 is preferably a structure in which any methylene group in the structure represented by -( _CH2 ) _b- is substituted with at least one group selected from the group consisting of ^-NR10- , ^-NR10 -CO-, ^-NR10- COO-, and ^-NR10 -CO- ^NR11- . Furthermore, if ^R10 and ^R11 are groups different from the protecting group, at least one of ^A7 and ^A8 is preferably a substituent having a portion of the structure represented by formula (1) as a substituent introduced into the aromatic ring. Additionally, ^Y1 does not have an aromatic cyclic group. r is 0 or 1, more preferably 1.

Specific examples of a particular diamine (A) include compounds represented by formulas (DA-1) to (DA-12). [Chemistry 6] [Chemistry 7] (In the formula, "Boc" represents tert-butoxycarbonyl; "Alloc" represents allyloxycarbonyl; and "F-moc" represents 9-fluorenylmethoxycarbonyl.)

In this context, the specific diamine (A) is preferably a compound represented by each of the formulas (DA-1) to (DA-10), and more preferably a compound represented by each of the formulas (DA-1), (DA-3) to (DA-6) and (DA-8).

The diamine compound used in the synthesis of polyamide [A] may be only a specific diamine (A), or it may be used with a diamine that is different from the specific diamine (A) (hereinafter also referred to as "other diamines (A)"). Examples of other diamines (A) include: aliphatic diamines, cycloaliphatic diamines, aromatic diamines, diamino organosilicones, etc. Specific examples of other diamines (A) include: 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenylpropane, 1,5-bis(4-aminophenoxy)pentane, 1,2-bis(4-aminophenoxy)ethane, 1,3-bis(4-aminophenoxy)propane, 1,6-bis(4-aminophenoxy)hexane, 6,6'-(pentamethylenedioxy)bis(3-aminopyridine), 4'-(2-(4-aminophenoxy)ethoxy)-[1,1'-biphenyl]-4-amine, 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, etc., diamine compounds having part of the structure Y in the main chain; diamine compounds, such as ortho-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4-aminophenyl-4-aminobenzoic acid ester, 2,5-diaminobenzoic acid, 3,5-diaminobenzoic acid, 4,4'-diaminodiphenyl ether, 2,2'-dimethyl-4,4'-diaminobiphenyl, and 3,5-diamino-N,N-bis(pyridin-3-ylmethyl)benzoamide, are diamine compounds that do not possess a partial Y structure in their main chain.

In the synthesis of polyacrylic acid [A], from the viewpoint of fully obtaining the improved adhesion with the sealant, the amount of a specific diamine (A) used relative to the total amount of diamine compounds used in the synthesis of polyacrylic acid [A] is preferably 10 mol% or more, more preferably 20 mol% or more, further preferably 25 mol% or more, and particularly preferably 35 mol% or more. Furthermore, from the viewpoint of fully obtaining the improved effect of AC afterimage reduction, the amount of diamines with partial structure Y used relative to the total amount of diamine compounds used in the synthesis of polyacrylic acid [A] (wherein, in the case that a specific diamine (A) has partial structure Y, the total amount of diamine compounds with partial structure Y in the main chain of the specific diamine (A) and other diamines (A)) is preferably 10 mol% or more, more preferably 20 mol% or more, further preferably 30 mol% or more, and particularly preferably 40 mol% or more.

Synthesis of Polyamide Polyamide [A] can be obtained by reacting a tetracarboxylic dianhydride with a diamine compound and, as desired, a molecular weight adjuster. In the synthesis reaction of polyamide, the preferred ratio of tetracarboxylic dianhydride to the diamine compound is 0.2 to 2 equivalents of the anhydride groups of the tetracarboxylic dianhydride relative to the amino groups of the diamine compound. Examples of molecular weight adjusters include: maleic anhydride, phthalic anhydride, itaconic anhydride, and other monoanhydrides; aniline, cyclohexylamine, n-butylamine, and other monoamine compounds; and phenyl isocyanate, naphthyl isocyanate, and other monoisocyanate compounds. The preferred ratio of the molecular weight adjuster is 20 parts by mass or less, relative to 100 parts by mass of the total tetracarboxylic dianhydride and diamine compound used.

The synthesis of polyamide is preferably carried out in an organic solvent. The preferred reaction temperature is -20°C to 150°C, and the preferred reaction time is 0.1 hours to 24 hours. Examples of organic solvents used in the reaction include: aprotic polar solvents, phenolic solvents, alcoholic solvents, ketone solvents, ester solvents, ether solvents, halogenated hydrocarbons, and hydrocarbons. As specific examples, it is preferred to use one or more of the group consisting of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphoric acid triamine, m-cresol, xylenol, and halogenated phenol as the reaction solvent, or to use one or more of these solvents mixed with other organic solvents (e.g., butyl solvent, diethylene glycol diethyl ether, etc.). The amount of organic solvent used (a) is preferably set as the total amount of tetracarboxylic dianhydride and diamine (b) relative to the total amount of the reaction solution (a+b) in an amount of 0.1% to 50% by mass.

A polymer solution containing dissolved polyamide [A] is obtained in the manner described above. The polymer solution can be used directly in the preparation of liquid crystal alignment agents, or it can be used in the preparation of liquid crystal alignment agents after the polyamide [A] contained in the polymer solution is separated.

(Polyamide) When polymer [A] is a polyamide, the polyamide can be obtained, for example, by methods such as: [I] reacting polyamide [A] with an esterifying agent; [II] reacting a tetracarboxylic acid diester with a diamine compound containing a specific diamine (A); [III] reacting a tetracarboxylic acid diester dihalide with a diamine compound containing a specific diamine (A). The polyamide may have only an amide structure, or it may be a partially esterified product containing both amide and amide structures. The reaction solution obtained by dissolving the polyamide can be directly used in the preparation of liquid crystal alignment agents, or it can be used in the preparation of liquid crystal alignment agents after separating the polyamide contained in the reaction solution. Furthermore, in this specification, "tetracarboxylic acid derivative" means that it includes tetracarboxylic dianhydrides, tetracarboxylic acid diesters, and tetracarboxylic acid diester dihalides.

(Polyimide) When polymer [A] is a polyimide, the polyimide can be obtained, for example, by dehydrating and cyclizing polyamide [A] synthesized in the manner described above, followed by amide imidization. The polyimide can be a fully amide-imide obtained by dehydrating and cyclizing all the amide structures of the polyamide precursor, or it can be a partially amide-imide obtained by dehydrating and cyclizing only a portion of the amide structure, resulting in the coexistence of the amide structure and the amide ring structure. The amide imidization rate of the polyimide is preferably 20% to 99%, more preferably 30% to 90%. Furthermore, the amide ratio is expressed as a percentage, representing the proportion of the number of amide ring structures relative to the total number of amide acid structures and amide ring structures in the polyimide. Here, a portion of the amide ring may be an isoamide ring.

The dehydration and ring-closing of polyacrylic acid is preferably carried out by the following method: dissolving polyacrylic acid in an organic solvent, adding a dehydrating agent and a dehydration and ring-closing catalyst to the solution, and heating as needed. In this method, anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride can be used as the dehydrating agent. The amount of dehydrating agent used is preferably set to 0.01 mol to 20 mol relative to 1 mol of the polyacrylic acid structure. Tertiary amines such as pyridine, trimethylpyridine, dimethylpyridine, and triethylamine can be used as the dehydration and ring-closing catalyst. The amount of dehydration ring-closing catalyst used is preferably set to 0.01 mol to 10 mol, relative to 1 mol of dehydrating agent. Examples of organic solvents used in the dehydration ring-closing reaction, such as those used in the synthesis of polyamides, can be listed as examples of organic solvents used in the dehydration ring-closing reaction. The reaction temperature of the dehydration ring-closing reaction is preferably 0°C to 180°C. The reaction time is preferably 1.0 h to 120 h. Furthermore, the reaction solution containing polyimide can be used directly in the preparation of liquid crystal alignment agents, or it can be used in the preparation of liquid crystal alignment agents after the polyimide has been separated.

<Polymer [B]> Polymer [B] is a polymer having a partial structure represented by the following formula (2). [Chemistry 8] (In formula (2), ^A1 and ^A4 are each independently a divalent aromatic cyclic group; ^R2 and ^R3 are each independently a hydrogen atom or a monovalent organic group; ^B1 is a single bond, ^-NR4- , -O- or a divalent aromatic heterocyclic group; ^R4 is a hydrogen atom or a monovalent organic group; when ^B1 is a single bond, ^A2 is a divalent aromatic cyclic group, and ^A3 is a single bond or a divalent aromatic cyclic group; when ^B1 is a divalent aromatic heterocyclic group, ^A2 and ^A3 are each independently a single bond or a divalent aromatic cyclic group; when ^B1 is ^-NR4- or -O-, ^A2 and ^A3 are each independently a divalent aromatic cyclic group, or represent A The aromatic rings of ^A and ^B are linked by single bonds or chains and together with -NR ^4- or -O- form a nitrogen- or oxygen-containing fused ring structure; "*" indicates a bond.

In formula (2), divalent aromatic hydrocarbons and divalent aromatic heterocyclic groups can be listed as the divalent aromatic cyclic groups of ^A1 and ^A4 . ^A1 and ^A4 may also have substituents in the aromatic ring portion. As the substituents, alkyl groups, halogen atoms, etc., having 1 to 5 carbon atoms can be listed. As preferred examples of ^A1 and ^A4 , divalent aromatic hydrocarbons can be groups formed by removing any two hydrogen atoms bonded to the carbon atoms of the rings forming a benzene ring, naphthalene ring, or anthracene ring; divalent aromatic heterocyclic groups can be groups formed by removing any two hydrogen atoms bonded to the carbon atoms of the rings forming a pyridine ring, pyrimidine ring, darazine ring, or pyrazine ring. Of these, ^A1 and ^A4 are preferably phenyl, biphenyl or pyridyl, with phenyl being particularly preferred.

Regarding ^R2 and ^R3 , the monovalent organic group is preferably a monovalent hydrocarbon or protecting group having 1 to 10 carbon atoms. The monovalent hydrocarbon is preferably an alkyl or phenyl group having 1 to 3 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms. Examples and preferred embodiments of the protecting group can be found in the description of ^R1 . Of these, ^R2 and ^R3 are preferably hydrogen atoms or monovalent hydrocarbons having 1 to 10 carbon atoms, and more preferably hydrogen atoms or alkyl groups having 1 to 3 carbon atoms.

^B1 is a single bond, ^-NR4- , -O-, or a divalent aromatic heterocyclic group. Examples of divalent aromatic heterocyclic groups include: groups formed by removing any two hydrogen atoms from a pyridine ring, pyrimidine ring, darazine ring, or pyrazine ring; groups formed by removing any two hydrogen atoms from a furan ring; and groups formed by removing any two hydrogen atoms from a thiophene ring. Among these, groups formed by removing any two hydrogen atoms from a pyrrole ring, furan ring, or thiophene ring are preferred, and groups formed by removing two hydrogen atoms from a pyrrole ring are even more preferred.

The monovalent organic group of ^R4 is preferably an alkyl or phenyl group having 1 to 3 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms.

When ^B1 is a single-bonded or divalent aromatic heterocyclic group, ^A2 and ^A3 are divalent aromatic cyclic groups, respectively. Examples and preferred embodiments of the divalent aromatic cyclic groups can be found in the description of the divalent aromatic cyclic groups ^A1 and ^A4 .

When ^B1 is ^-NR4- or -O-, the description of the divalent aromatic cyclic groups of ^A1 and ^A4 can be cited as an example of the divalent aromatic cyclic groups of ^A2 and ^A3 . When ^A2 and ^A3 represent nitrogen-containing fused ring structures formed by the linkage of the aromatic rings of ^A2 and ^A3 through single bonds or chain structures (e.g., ethyl groups) and together with ^-NR4- , examples of such fused ring structures include: carbazole structures, 9-methylcarbazole structures, 9-ethylcarbazole structures, etc. In the case where ^A2 and ^A3 represent an oxygen-containing fused ring structure formed by the linkage of the aromatic rings of ^A2 and ^A3 through a single bond or chain structure (e.g., ethylenyl) and together with -O-, the dibenzofuran structure and the like can be listed as such fused ring structures.

The partial structure represented by formula (2) has a total of three or more aromatic rings (including aromatic hydrocarbon rings and aromatic heterocyclic rings), and is particularly preferred to have four or more. In the case where the partial structure represented by formula (2) contains a total of four or more aromatic rings, the residual charge is further slowed down by the elongation of the conjugate structure, which can sufficiently reduce image retention (especially DC image retention), and is therefore preferred in this respect. Of these, it is particularly preferred that the partial structure represented by formula (2) has a biphenyl structure.

The backbone of polymer [B] is not particularly limited and can be appropriately selected based on the backbone of polymer [A]. When polymer [A] is selected from at least one of the group consisting of polyamide, polyamide ester and polyimide, polymer [B] is preferably selected from at least one of the group consisting of polyamide, polyamide ester and polyimide in order to improve the affinity with polymer [A].

(Polyamide) In the case where polymer [B] is polyamide, for ease of incorporating the partial structure represented by formula (2) into the polymer, the polyamide (hereinafter also referred to as "polyamide [B]") is preferably a polymer obtained by reacting a tetracarboxylic dianhydride with a diamine compound containing a diamine (hereinafter also referred to as "specific diamine (B)") having the partial structure represented by formula (2). Examples of tetracarboxylic dianhydrides used in the synthesis of polyamide [B] include compounds used in the synthesis of polyamide [A]. The tetracarboxylic dianhydride used in the synthesis of polyamide [B] is preferably an alicyclic tetracarboxylic dianhydride. For an explanation of the amount of alicyclic tetracarboxylic dianhydride used, refer to the description of polyamide [A].

The specific diamine (B) used in the synthesis of polymer [B] is preferably the compound represented by formula (2-1) below. [Chemistry 9] (In equation (2-1), ^A1 to ^A4 , ^B1 , ^R2 and ^R3 have the same meaning as in equation (2).)

Specific examples of certain diamines (B) include compounds represented by formulas (DA-19) to (DA-27), (DA-42), and (DA-43). [Chemistry 10]

[Chemistry 11]

In this context, the specific diamine (B) is preferably a compound represented by each of the formulas (DA-19) to (DA-25) and (DA-42), more preferably a compound represented by each of the formulas (DA-19) to (DA-23) and (DA-42), and even more preferably a compound represented by each of the formulas (DA-19) to (DA-21).

The diamine compound used in the synthesis of polyamide [B] may be only a specific diamine (B), or it may be a diamine that is different from the specific diamine (B) (hereinafter also referred to as "other diamines (B)"). Examples of other diamines (B) include: aliphatic diamines, cycloaliphatic diamines, aromatic diamines, etc. Specific examples of other diamines (B) include diamine compounds that do not have part of structure Y in the main chain, as illustrated in the description of polymer [A]. Polymer [B] is preferably any structure that does not have part of structure Y and part of structure X as described below.

In terms of fully reducing image retention (especially DC image retention) during the synthesis of polymer [B], the amount of a specific diamine (B) used is preferably 2 mol% or more, more preferably 5 mol% or more, and even more preferably 10 mol% or more, relative to the total amount of diamine compounds used in the synthesis of polymer [B]. Furthermore, the amount of the specific diamine (B) used can be arbitrarily set within the range of 100 mol% or less, relative to the total amount of diamine compounds used in the synthesis of polymer [B]. In terms of improving the coatability of the liquid crystal alignment agent to the substrate, it is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 80 mol% or less.

Furthermore, polyamide [B], polyamide ester, and polyimide, which are polymers [B], can also be manufactured in the same manner as polymer [A]. For details regarding the various conditions in the synthesis methods of the polymers such as polyamide [B], please refer to the description of polymer [A].

<Polymer [C]> Polymer [C] is a polymer having the following partial structure X in the main chain. By including polymer [A] and polymer [B] and polymer [C] having partial structure X in the liquid crystal alignment agent, it is possible to improve the adhesion of the sealant and reduce image retention (AC image retention and DC image retention), and at the same time improve the adhesion between the liquid crystal alignment film and the substrate (especially the adhesion between the spacer portion and the substrate), which is preferred in this respect. Partial structure X: a structure represented by -( _CH2 ) _a- (where a is an integer from 2 to 20), or a structure in which any methylene group in the structure represented by -( _CH2 ) _a- is substituted with at least one group selected from the group consisting of ^-NR7- , -O-, -COO-, ^-NR7 -CO-, ^-NR7 -COO-, ^-NR8 -CO- ^NR9- and nitrogen-containing non-aromatic heterocyclic groups (where ^R7 is a hydrogen atom or alkyl group; ^R8 and ^R9 are each independently a hydrogen atom or alkyl group, or represent a ring structure formed by ^R8 and ^R9 combined with the nitrogen atom bonded to ^R8 , the nitrogen atom bonded to ^R9 , and -CO-; in partial structure X, ^-NR7- , -O-, -COO-, ^-NR7 -CO-, -NR ^7- COO-, -NR ⁸ -CO-NR ^9- and nitrogen-containing non-aromatic heterocyclic groups are not adjacent to each other.

In partial structure X, from the perspective of improving the adhesion between the substrate and the liquid crystal alignment film at the spacer configuration portion, it is preferable to include a linear alkyl diester with 2 or more carbon atoms in partial structure X. Furthermore, from the viewpoint of suppressing the reduction in film strength, a is preferably 12 or less, and more preferably 10 or less.

^R7 , ^R8 , and ^R9 are preferably hydrogen atoms or methyl groups, and more preferably hydrogen atoms. Examples of ring structures formed by the combination of ^R8 and ^R9 include 2-oxo-4-imidazolone-1,3-diyl. Examples of nitrogen-containing non-aromatic heterocyclic groups include piperidine-1,4-diyl and piperazine-1,4-diyl. Furthermore, polymer [C] does not possess the partial structures represented by formula (1) and the partial structures represented by formula (2).

In this embodiment, the partial structure X is preferably a structure having at least one group selected from the group consisting of -COO-, ^-NR7 -CO-, ^-NR7- COO-, and ^-NR8 -CO- ^NR9- . Because the partial structure X has such a hydrogen-bonded functional group, it tends to easily separate from the polymer [A] layer, which is preferable for improving the adhesion between the liquid crystal alignment film and the substrate. In particular, for improving the adhesion to the substrate, the partial structure X is preferably composed of at least one group selected from the group consisting of -COO-, ^-NR7 -CO-, -NR7 ^- COO-, and ^-NR8 -CO- ^NR9- , and a linear alkyl dimethyl group having two or more carbon atoms.

The backbone of polymer [C] is not particularly limited. However, when polymer [A] is selected from at least one of the group consisting of polyamide, polyamide ester and polyimide, polymer [C] is also preferably selected from at least one of the group consisting of polyamide, polyamide ester and polyimide in order to improve the affinity with polymer [A] and facilitate the introduction of part of structure X into the backbone of the polymer.

In the case where polymer [C] is polyamide, the polyamide (hereinafter also referred to as "polyamide [C]") is preferably a polymer obtained by reacting a tetracarboxylic dianhydride with a diamine compound containing a diamine (hereinafter also referred to as "specific diamine (C)") having a portion of structure X. Examples of tetracarboxylic dianhydrides used in the synthesis of polyamide [C] include compounds used in the synthesis of polyamide [A]. The tetracarboxylic dianhydride used in the synthesis of polyamide [C] is preferably an alicyclic tetracarboxylic dianhydride. For an explanation of the amount of alicyclic tetracarboxylic dianhydride used, refer to the description of polyamide [A].

The specific diamine (C) is not specifically defined if it is a diamine compound having part of the structure X; for example, aliphatic diamines, cycloaliphatic diamines, aromatic diamines, etc., can be listed. The specific diamine (C) is preferably a compound represented by the following formula (3-1). [Chemistry 12] (In formula (3-1), ^A5 is a divalent aromatic cyclic group; ^A6 is a single bond or a divalent aromatic cyclic group; ^Y2 is a divalent group with partial structure X; ^R5 is a hydrogen atom or a monovalent organic group)

In the above formula (3-1), divalent aromatic hydrocarbons and divalent aromatic heterocyclic groups can be listed as the divalent aromatic cyclic groups of ^A5 and ^A6 . For specific examples and preferred examples of the divalent aromatic cyclic groups of ^A5 and ^A6 , the description of the divalent aromatic cyclic groups of ^A1 and ^A4 in the above formula (2) can be referred to.

As a monovalent organic group of R ⁵ , monovalent hydrocarbons having 1 to 10 carbon atoms can be listed. ^{R 5} is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and more preferably a hydrogen atom or a methyl group.

^Y2 is a divalent group having part of structure X, such as: a divalent group formed by substituting any methylene group in the structure represented by - _{( CH2} ) _{a- or} by substituting at least one of the group consisting of ^-NR7- , -O-, -COO-, ^-NR7 -CO-, ^-NR7 -COO-, ^-NR8 -CO- ^NR9- and nitrogen-containing non-aromatic heterocyclic groups (hereinafter also referred to as "heterocyclic group (c)"), or a divalent group formed by bonding at least one (more than one) of -( _CH2 ) _a- and heterocyclic groups (c) with a pentyrannyl alkyl group (preferably pentyrannyl). Furthermore, ^Y2 does not have an aromatic cyclic group.

Specific examples of certain diamines (C) include aliphatic diamines such as m-xylylenediamine, pentamethyldiamine, and hexamethylenediamine; alicyclic diamines such as 4,4'-methylenebis(cyclohexylamine); and aromatic diamines such as 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenylpropane, 1,3-bis(4-aminophenylethyl)urea, 1,3-bis(4-aminobenzyl)urea, 1,5-bis(4-aminophenoxy)pentane, and 1, 4-Bis(4-aminophenoxy)butane, 1,3-bis(4-aminophenoxy)propane, 1,6-bis(4-aminophenoxy)hexane, bis[2-(4-aminophenyl)ethyl]adipic acid, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-[4,4'-propane-1,3-diylbis(piperidine-1,4-diyl)]diphenylamine, diethylene glycol bis(4-aminophenyl) ether, and compounds represented by each of the following formulas (DA-32) to (DA-40). [Chemistry 13]

In the compounds represented by formulas (DA-32) to (DA-40), the specific diamine (C) is preferably a compound represented by formulas (DA-32) to (DA-35), and more preferably a compound represented by formulas (DA-32) to (DA-34).

The diamine compound used in the synthesis of polyamide [C] may be only a specific diamine (C), or it may be used with a diamine that is different from the specific diamine (C) (hereinafter also referred to as "other diamines (C)"). As other diamines (C), examples that are different from the specific diamine (A) to the specific diamine (C) can be listed, such as the diamine compound that does not have part of the structure Y in the main chain as illustrated in the description of polymer [A].

In synthesizing polymer [C], from the viewpoint of sufficiently improving adhesion to the substrate, the amount of a specific diamine (C) used relative to the total amount of diamine compounds used in the synthesis of polymer [C] is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more. Furthermore, the amount of the specific diamine (C) used relative to the total amount of diamine compounds used in the synthesis of polymer [C] can be arbitrarily set within a range of 100 mol% or less.

Furthermore, polyamide [C], polyamide ester, and polyimide, which are polymers [C], can also be manufactured in the same manner as polymer [A]. For details regarding the various conditions in the synthesis methods of polyamide [C] and other polymers, please refer to the description of polymer [A].

For polymers [A], [B], and [C] used in the preparation of the liquid crystal alignment agent, regarding the solution viscosity of the polymers, when preparing a solution with a concentration of 10% by mass, a solution viscosity of 10 mPa·s to 800 mPa·s is preferred, and a solution viscosity of 15 mPa·s to 500 mPa·s is more preferred. Furthermore, the solution viscosity (mPa·s) is the value obtained by measuring a 10% by mass polymer solution prepared using a type E rotational viscometer at 25°C using a good solvent for the polymer (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

For each of polymers [A], [B], and [C], the weight-average molecular weight (Mw) of polystyrene, as determined by gel permeation chromatography (GPC), is preferably 1,000 to 500,000, more preferably 2,000 to 300,000. Furthermore, the molecular weight distribution (Mw/Mn), expressed as the ratio of Mw to the number-average molecular weight (Mn) of polystyrene as determined by GPC, is preferably 7 or less, more preferably 5 or less.

In liquid crystal alignment agents, from the viewpoint of fully obtaining the improvement effect on the sealing performance of the sealant, the content of polymer [A] relative to the total amount of polymer components contained in the liquid crystal alignment agent is preferably 1% by mass or more, more preferably 2% by mass or more, further preferably 5% by mass or more, and further preferably 10% by mass or more. Furthermore, relative to the total amount of polymer components contained in the liquid crystal alignment agent, the content of polymer [A] is preferably 70% by mass or less, more preferably 60% by mass or less, and further preferably 50% by mass or less.

Regarding the improvement of image retention (especially DC image retention) reduction, the content of polymer [B] is preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to the total amount of polymer components contained in the liquid crystal alignment agent. Furthermore, regarding the improvement of the coatability of the liquid crystal alignment agent, the content of polymer [B] is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less, relative to the total amount of polymer components contained in the liquid crystal alignment agent.

Regarding the improvement in adhesion to the substrate, the content of polymer [C] is preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to the total amount of polymer components contained in the liquid crystal alignment agent. Furthermore, regarding the improvement in the coatability of the liquid crystal alignment agent, the content of polymer [C] is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less, relative to the total amount of polymer components contained in the liquid crystal alignment agent.

Here, polymer [A] is hydrophobic by protecting the -NH- group, thus it is believed that it tends to exist on the film surface when the liquid crystal alignment agent is coated on the substrate. In addition, regarding the ^-NR1- of polymer [A], it is believed that, for example, the protecting group ( ^R1 ) is removed and replaced by hydrogen atoms during post-baking during film formation, thereby creating a polar functional group. Therefore, regarding liquid crystal alignment agents containing polymer [A], it is believed that: during film formation, the solubility of the solvent is high and polymer [A] tends to exist on the surface; and after film formation, the adhesion to the sealant becomes good due to the removal of the protecting group. Even when a sealant is formed on the surface of the liquid crystal alignment film, peeling is not likely to occur, and a highly reliable liquid crystal element can be obtained.

Furthermore, it is believed that in order to achieve further high performance of liquid crystal elements, polymer [B] having a specific nitrogen-containing conjugated structure represented by the above formula (2) is formulated together with polymer [A] in the liquid crystal alignment agent, thereby showing a reduction effect on DC retention. However, it is believed that the presence of more aromatic rings in the partial structure represented by the above formula (2) reduces the toughness of the formed liquid crystal alignment film (especially the lower part), thereby making it easy for the liquid crystal alignment film to peel off from the substrate under external force, for example, and deteriorating the adhesion between the liquid crystal alignment film and the substrate, especially the adhesion between the substrate and the liquid crystal alignment film at the spacer placement area.

In contrast, it is speculated that by producing a liquid crystal alignment agent containing polymer [A], polymer [B] and polymer [C], a liquid crystal alignment film can be formed that has excellent adhesion to the sealant and reduction of DC afterimages, while also having excellent adhesion to the substrate (especially the spacer area).

<Other Components> In addition to polymers [A], [B], and [C], the liquid crystal alignment agent may also contain components different from polymers [A], [B], and [C] (hereinafter referred to as "other components"), as needed.

(Other Polymers) The liquid crystal alignment agent disclosed herein may also contain polymers different from polymers [A], [B], and [C] (hereinafter also referred to as "other polymers") as polymer components. The main backbone of other polymers is not particularly limited. Examples of other polymers include: polyamides, polyamide esters, polyimides, polyorganosiloxanes, polyesters, polyenamines, polyureas, polyamides, polyamide-imides, polybenzoxazole precursors, polybenzoxazoles, cellulose derivatives, polyacetals, (meth)acrylic polymers, styrene polymers, maleimide polymers, or styrene-maleimide polymers. From the viewpoint of high affinity for liquid crystals when used in conjunction with polymers [A], [B], and [C], and improved reliability of liquid crystal elements, other polymers are preferably selected from at least one of the group consisting of polyamide, polyamide ester, and polyimide.

When the liquid crystal alignment agent contains other polymers, the content of the other polymers can be appropriately set within a range that does not impair the effect of the present invention. Specifically, the content of the other polymers is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less, relative to the total amount of polymer components contained in the liquid crystal alignment agent.

(Soluble) The liquid crystal alignment agent disclosed herein is prepared in the form of a liquid composition consisting of polymer [A], polymer [B], polymer [C], and other components used as needed, preferably dispersed or dissolved in a suitable solvent.

Organic solvents are preferred. Specific examples include: N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,2-dimethyl-2-imidazolium ketone, 1,3-dimethyl-2-imidazolium ketone, phenol, γ-butyrolactone, γ-butyrolactamine, N,N-dimethylformamide, N,N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone, diacetone alcohol, 1-hexanol, 2-hexanol, propane-1,2-diol, 3-methoxy-1-butanol, ethylene glycol monomethyl ether, methyl lactate, ethyl lactate, butyl lactate, methyl acetate, ethyl acetate, butyl acetate, and acetoacetic acid. Methyl acetate, ethyl acetoate, ethyl propionate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-isopropyl ether, ethylene glycol-n-butyl ether (butyl solvent), 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, diisoamyl ether, ethyl acetate, propyl acetate, propylene glycol monomethyl ether (Propylene) Glycol Monomethyl Ether (PGME), diethylene glycol diethyl ether acetate, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol diacetate, cyclopentanone, cyclohexanone, etc.

Other components contained in the liquid crystal alignment agent, besides those mentioned above, may include, for example, antioxidants, metal chelate compounds, curing accelerators, surfactants, fillers, dispersants, and photosensitizers. The formulation ratios of other components may be appropriately selected based on the specific compounds, without compromising the effects of this disclosure.

The solid content concentration in the liquid crystal alignment agent (the proportion of the total mass of components other than the solvent in the total mass of the liquid crystal alignment agent) should be appropriately selected considering factors such as viscosity and volatility, preferably in the range of 1% to 10% by mass. If the solid content concentration is 1% by mass or more, the film thickness can be sufficiently ensured, and a liquid crystal alignment film exhibiting good liquid crystal alignment can be easily obtained. On the other hand, if the solid content concentration is 10% by mass or less, the coating thickness can be appropriately achieved, and a liquid crystal alignment film exhibiting good liquid crystal alignment can be easily obtained. In addition, the viscosity of the liquid crystal alignment agent becomes suitable, tending to result in good coatability.

《Liquid Crystal Alignment Film and Liquid Crystal Element》 The liquid crystal alignment film disclosed herein can be manufactured using a liquid crystal alignment agent prepared as described above. Furthermore, the liquid crystal element disclosed herein includes a liquid crystal alignment film formed using the liquid crystal alignment agent described above. The driving method of the liquid crystal in the liquid crystal element is not particularly limited, and can be applied to various modes such as TN type, Super Twisted Nematic (STN) type, VA type (including Vertical Alignment-Multi-domain Vertical Alignment (VA-MVA) type, Vertical Alignment-Patterned Vertical Alignment (VA-PVA) type, IPS type, FFS type, Optically Compensated Bend (OCB) type, Polymer Sustained Alignment (PSA) type, etc. Liquid crystal elements can be manufactured, for example, by a method including steps 1 to 3 below. In step 1, the substrate used varies depending on the desired operating mode. Steps 2 and 3 are common to all operating modes.

<Step 1: Coating Formation> First, a coating is formed on the substrate by coating a liquid crystal alignment agent onto the substrate, preferably by heating the coated surface. As the substrate, examples include: float glass, sodium glass, and other glass; transparent substrates containing plastics such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, and poly(alicyclic olefins). Examples of transparent conductive films disposed on one side of the substrate include NESA films (registered trademark of PPG Industries, Inc.) containing tin oxide ( _SnO₂ ) and indium tin oxide ( _ITO ) films containing indium oxide-tin oxide ( _In₂O₃ - _SnO₂ ). In manufacturing TN, STN, or VA type liquid crystal elements, two substrates with patterned transparent conductive films are used. On the other hand, in manufacturing IPS or FFS type liquid crystal elements, a substrate with patterned comb-shaped electrodes and an opposing substrate without electrodes are used.

There are no particular limitations on the coating method of liquid crystal alignment agents on the substrate. For example, it can be applied by spin coating, printing (such as offset printing, flexographic printing, etc.), inkjet coating, slot coating, rod coating, extrusion die coating, direct gravure coating, chamber doctor coating, offset gravure coating, impregnation coating, MB coating, etc.

After applying the liquid crystal alignment agent, preheating (pre-baking) is preferably performed to prevent sagging of the applied liquid crystal alignment agent. The pre-baking temperature is preferably 30°C to 200°C, and the pre-baking time is preferably 0.25 minutes to 10 minutes. Subsequently, the solvent is completely removed, and a calcination (post-baking) step is performed as needed for the purpose of thermally imidizing the acetic acid structures present in the polymer. The calcination temperature (post-baking temperature) is preferably 80°C to 280°C, more preferably 80°C to 250°C. The post-baking time is preferably 5 minutes to 200 minutes. The film thickness of the formed film is preferably 0.001 μm to 1 μm. Thus, a film comprising polymer [A'], polymer [B] and polymer [C] can be formed on a substrate, wherein polymer [A'] is formed by separating the protecting group from the partial structure represented by formula (1) of polymer [A]. Furthermore, polymer [A'] has structural units containing -NH- groups in portions different from the groups participating in polymerization.

<Step 2: Alignment Treatment> In manufacturing TN, STN, IPS, or FFS type liquid crystal elements, an alignment treatment is performed to impart liquid crystal alignment capability to the coating formed in Step 1 (alignment treatment). This imparts the alignment capability of the liquid crystal molecules to the coating, forming a liquid crystal alignment film. Preferably, the alignment treatment involves rubbing the surface of the coating formed on the substrate with cotton or the like, or photoalignment treatment by irradiating the coating with light to impart liquid crystal alignment capability. In manufacturing vertically aligned liquid crystal elements, the coating formed in Step 1 can be used directly as a liquid crystal alignment film; however, alignment treatment can also be performed on the coating to further improve the liquid crystal alignment capability.

Irradiation for photoorientation can be performed by methods such as: irradiating a coating after a post-baking step; irradiating a coating after a pre-baking step and before a post-baking step; or irradiating the coating while it is being heated in at least one of the pre-baking or post-baking steps. The radiation irradiating the coating can be, for example, ultraviolet light or visible light with wavelengths from 150 nm to 800 nm. Ultraviolet light with wavelengths from 200 nm to 400 nm is preferred. When the radiation is polarized, it can be linearly polarized or partially polarized. When the radiation used is linearly polarized or partially polarized, irradiation can be performed from a direction perpendicular to the substrate surface, from an oblique direction, or a combination of these directions. When irradiating unpolarized light, the irradiation direction is set to an oblique direction.

Examples of light sources used include: low-pressure mercury lamps, high-pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonant lamps, xenon lamps, and excimer lasers. The radiation dose is preferably 200 J/ ^m² to 30,000 J/ ^m² , more preferably 500 J/ ^m² to 10,000 J/ ^m² . After irradiation with light to impart alignment capability, the substrate surface may be cleaned using, for example, water, an organic solvent (e.g., methanol, isopropanol, 1-methoxy-2-propanol acetate, butyl solvent, ethyl lactate, etc.), or a mixture thereof, or the substrate may be heated.

<Step 3: Construction of Liquid Crystal Cells> Prepare two substrates with liquid crystal alignment films formed as described above, and place liquid crystal between the two substrates facing each other to manufacture a liquid crystal cell. When manufacturing the liquid crystal cell, methods such as: placing two substrates facing each other with liquid crystal alignment films facing each other and a gap between them; bonding the peripheries of the two substrates together using a sealant; injecting liquid crystal into the cell gap surrounded by the substrate surface and the sealant; and then sealing the injection hole; or using a liquid crystal drop filling (ODF) method. A bead-shaped or columnar spacer is placed between the two substrates as an in-plane spacer, thereby forming the cell gap. As a sealant, for example, an epoxy resin containing a hardener and alumina spheres as spacers can be used. When applying a sealant to a substrate, it can be done, for example, by screen printing, on the surface of the liquid crystal alignment film on at least one of the two substrates on which the liquid crystal alignment film is formed.

As a liquid crystal, either positive or negative type can be used, with negative type being preferred. Examples of negative type liquid crystals include Merck's "MLC-6608," "MLC-6609," "MLC-6610," and "MLC-7026-100." In particular, using negative type liquid crystals in IPS and FFS type liquid crystal elements can reduce transmission losses above the electrodes, resulting in improved contrast, making it a preferred choice in this respect. Furthermore, nematic liquid crystals and dish-type liquid crystals can be included as liquid crystals, with nematic liquid crystals being preferred.

In the manufacture of a liquid crystal display device, a polarizing plate is then attached to the outer surface of the liquid crystal cell to obtain a liquid crystal display element. Examples of polarizing plates include those made by sandwiching a polarizing film called an "H-film" between a cellulose acetate protective film and a polarizing plate containing the H-film itself. The "H-film" is a film in which polyvinyl alcohol is extended and aligned while absorbing iodine.

The liquid crystal element of this invention can be effectively applied to a variety of uses. Specifically, it can be used in clocks, portable game consoles, word processors, laptop computers, car navigation systems, camcorders, personal digital assistants (PDAs), digital cameras, mobile phones, smartphones, various surveillance cameras, LCD televisions, information displays, and other display devices or dimming devices, retardation films, etc. [Examples]

The following embodiments provide a more detailed description of the implementation methods, but the present invention is not to be construed as limited by the following embodiments.

In the following examples, the weight-average molecular weight (Mw) of the polymer, the amide content of the polyimide in the polymer solution, and the solution viscosity of the polymer solution are determined by the following methods. The required amounts of the starting materials and polymers used in the following embodiments are ensured by repeatedly performing the synthesis at the scale shown in the following synthesis examples as needed. [Weight-average molecular weight of the polymer Mw] The weight-average molecular weight (Mw) is the polystyrene equivalent determined by GPC under the following conditions. Column: Tosoh Corporation, TSKgel GRCXLII; Solvent: N,N-dimethylformamide solution containing lithium bromide and phosphoric acid; Temperature: 40℃; Pressure: 68 kgf/ ^cm²; [Imidification rate of polyimide] The polyimide solution was added to pure water, and the obtained precipitate was thoroughly depressurized and dried at room temperature. It was then dissolved in dimethyl deuteride and ^1H -Nuclear Magnetic Resonance ( ^1H -NMR) was measured at room temperature using tetramethylsilane as a reference material. The ^1H -NMR was calculated based on the obtained ^1H -NMR spectrum using the following formula (1). The acetilimation rate [%] = (1 - ( ^β1 / ( ^β2 × α))) × 100 … (1) (In formula (1), ^β1 is the peak area of protons originating from NH groups that appear near the chemical shift of 10 ppm, ^β2 is the peak area of other protons, and α is the proportion of other protons relative to the number of 1 proton of NH groups in the polymer precursor (polyacrylic acid)) [Solution viscosity of polymer solution] The solution viscosity (mPa·s) of the polymer solution was measured at 25°C using an E-type rotational viscometer.

The abbreviations of the compounds used in the embodiments are as follows. (Tetracarboxylic acid derivatives) ·Compounds (AN-1) to (AN-8): The compounds represented by each of the following formulas (AN-1) to (AN-8) [Chemistry 14]

(Diamine compounds) · Compounds (DA-1) to (DA-12): Compounds represented by each of the formulas (DA-1) to (DA-12) · Compounds (DA-19) to (DA-27), Compound (DA-42): Compounds represented by each of the formulas (DA-19) to (DA-27) and (DA-42) · Compounds (DA-32) to (DA-40): Compounds represented by each of the formulas (DA-32) to (DA-40) · Compounds (DA-13) to (DA-18), Compounds (DA-28) to (DA-31), Compound (DA-41): Compounds represented by each of the formulas (DA-13) to (DA-18), (DA-28) to (DA-31), and (DA-41) [Chemical 15]

<Polymer Synthesis> 1. Synthesis of Polyamide [Synthesis Example 1] Compound (DA-1) was dissolved in N-methyl-2-pyrrolidone (NMP), and 0.95 molars of compound (AN-1) were added. The reaction was carried out at 60°C for 6 hours to obtain a solution containing 15% by mass of polyamide. A small amount of the obtained polyamide solution was aliquoted, and NMP was added to prepare a solution with a polyamide concentration of 10% by mass. The viscosity of the obtained solution was measured to be 128 mPa·s. Subsequently, the polyamide solution was injected into a large amount of excess methanol to precipitate the reaction product. The precipitate was washed with methanol and dried under reduced pressure at 40°C for 15 hours to obtain polyamide (denoted as "polymer (A-1)"). The obtained polymer has a weight-average molecular weight (Mw) of 27,000.

[Synthesis Examples 2-8, 11-16, 18-53: Synthesis of polymers (A-2), (A-8), (A-11), (A-16), (A-18), (A-19), (B-1), (B-20), (C-1), and (C-1) (C-14)] The types and molar ratios of tetracarboxylic dianhydrides and diamine compounds were changed as described in Tables 1-4 below. Otherwise, polymers (A-2), (A-8), (A-11), (A-16), (A-18), (A-19), (B-1), (B-20), and (C-1) (C-14) were obtained, similarly to Synthesis Example 1. Furthermore, regarding the values in Tables 1-4, for acid derivatives (tetracarboxylic dianhydride in the synthesis of polyacrylic acid), the values represent the proportion (in mol) of each compound relative to 100 mol of the total amount of acid derivatives used in the synthesis; for diamine compounds, the values represent the proportion (in mol) of each compound relative to 100 mol of the total amount of diamine compounds used in the synthesis.

[Synthesis Example 17: Synthesis of Polymer (A-17)] Compound (DA-13) was dissolved in N-methyl-2-pyrrolidone (NMP), and 0.95 equivalents (molar ratio) of compound (AN-1) were added. The reaction was carried out at 60°C for 6 hours to obtain a solution containing 15% by mass of polyacrylic acid. 0.05 equivalents (molar ratio) of di-tert-butyl dicarbonate was added to the polyacrylic acid solution, and the mixture was stirred at room temperature for 15 hours. Subsequently, the polyacrylic acid solution was injected into a large amount of excess methanol to precipitate the reaction products. The precipitate was washed with methanol and dried under reduced pressure at 40°C for 15 hours to obtain a polyamide with Boc groups at the ends (denoted as "polymer (A-17)"). The obtained polymer had a weight-average molecular weight (Mw) of 25,000.

2. Synthesis of Polyimide [Synthesis Example 9: Synthesis of Polymer (A-9)] The types and molar ratios of the tetracarboxylic dianhydride and diamine compound were changed as described in Table 1 below. Otherwise, polymerization was carried out in the same manner as in Synthesis Example 1 to obtain a solution containing 15% by mass of polyamide. Then, NMP was added to the obtained polyamide solution to prepare a solution with a polyamide concentration of 10% by mass. Pyridine and acetic anhydride were added, and a dehydration and ring-closing reaction was carried out at 60°C for 4 hours. After the dehydration and ring-closing reaction, the solvent in the system was replaced with fresh NMP, thereby obtaining a solution containing 15% by mass of polyamide with an imidization rate of approximately 85%. Next, the polyimide solution was injected into a large amount of excess methanol, causing the reaction product to precipitate. The precipitate was washed with methanol and dried under reduced pressure at 40°C for 15 hours, thereby obtaining polyimide (denoted as "Polymer (A-9)"). The weight-average molecular weight (Mw) of the obtained polymer was 33,000.

3. Synthesis of Polyamide Ester [Synthesis Example 10: Synthesis of Polymer (A-10)] 70 mol of compound (DA-5) as a diamine, 15 mol of compound (DA-6) and 15 mol of compound (DA-3) as a diamine, pyridine as a base in an amount of 2.5 equivalents (molar ratio) relative to the total amount of the diamine compounds, and N-methyl-2-pyrrolidone (NMP) as a solvent were added and dissolved. While water-cooling and stirring the solution, 97 mol of dimethyl-1,3-bis(chlorocarbonyl)cyclobutane-2,4-carboxylic acid ester as an acid derivative was added, followed by NMP at a solid content concentration of 5% by mass. The mixture was water-cooled and stirred for 4 hours. The solution was injected into water to precipitate the polymer. The polymer was then filtered by suction filtration, washed again with water, and then washed three times with methanol. The mixture was then dried under reduced pressure at 40°C to obtain polyamide (denoted as "polymer (A-10)"). The weight-average molecular weight (Mw) of polymer (A-10) is 29,000.

[Table 1] Polymer name acid derivatives diamine compounds Acid 1 (Morby) Acid 2 (Morby) Diamine 1 (Morbyl) Diamine-2 (Morbyl) Diamine-3 (Morbyl) Synthesis example 1 A-1 AN-1 (100) DA-1 (100) Synthesis example 2 A-2 AN-1 (100) DA-1 (70) DA-15 (30) Synthesis example 3 A-3 AN-1 (70) AN-3 (30) DA-1 (60) DA-16 (40) Synthesis example 4 A-4 AN-1 (100) DA-1 (80) DA-17 (20) Synthesis example 5 A-5 AN-1 (100) DA-1 (60) DA-3 (30) DA-18 (10) Synthesis example 6 A-6 AN-1 (60) AN-3 (40) DA-2 (100) Synthesis Example 7 A-7 AN-2 (95) AN-6 (5) DA-3 (100) Synthesis example 8 A-8 AN-2 (100) DA-6 (100) Synthesis example 9 A-9 AN-2 (80) AN-3 (20) DA-4 (80) DA-16 (20) Synthesis example 10 A-10 AN-8 (100) DA-5 (70) DA-6 (15) DA-3 (15) Synthesis Example 11 A-11 AN-3 (70) AN-6 (30) DA-7 (100) Synthesis example 12 A-12 AN-4 (50) AN-6 (50) DA-8 (100) Synthesis example 13 A-13 AN-4 (50) AN-6 (50) DA-9 (100) Synthesis Example 14 A-14 AN-6 (100) DA-10 (100) Synthesis Example 15 A-15 AN-6 (100) DA-11 (100) Synthesis Example 16 A-16 AN-7 (100) DA-12 (100) Synthesis Example 17 A-17 AN-1 (100) DA-13 (100) Synthesis example 18 A-18 AN-1 (100) DA-13 (100) Synthesis example 19 A-19 AN-1 (70) AN-3 (30) DA-14 (70) DA-16 (30)

[Table 2] Polymer name acid derivatives diamine compounds Acid 1 (Morby) Acid 2 (Morby) Diamine 1 (Morbyl) Diamine-2 (Morbyl) Diamine-3 (Morbyl) Synthesis example 20 B-1 AN-1 (100) DA-19 (80) DA-30 (20) Synthesis Example 21 B-2 AN-1 (70) AN-3 (30) DA-20 (60) DA-30 (40) Synthesis example 22 B-3 AN-1 (100) DA-20 (10) DA-31 (90) Synthesis example 23 B-4 AN-1 (90) AN-3 (10) DA-21 (100) Synthesis example 24 B-5 AN-2 (100) DA-22 (100) Synthesis example 25 B-6 AN-2 (80) AN-3 (20) DA-22 (80) DA-30 (20) Synthesis Example 26 B-7 AN-3 (100) DA-22 (60) DA-30 (40) Synthesis Example 27 B-8 AN-3 (100) DA-22 (30) DA-30 (70) Synthesis example 28 B-9 AN-3 (50) AN-4 (50) DA-22 (10) DA-30 (90) Synthesis Example 29 B-10 AN-3 (70) AN-5 (30) DA-22 (5) DA-30 (95) Synthesis example 30 B-11 AN-4 (100) DA-22 (60) DA-30 (30) DA-18 (10) Synthesis Example 31 B-12 AN-4 (50) AN-5 (50) DA-23 (10) DA-30 (90) Synthesis example 32 B-13 AN-5 (100) DA-24 (100) Synthesis example 33 B-14 AN-5 (100) DA-25 (45) DA-31 (45) DA-18 (10) Synthesis example 34 B-15 AN-5 (70) AN-6 (30) DA-26 (100) Synthesis Example 35 B-16 AN-6 (100) DA-27 (100) Synthesis Example 36 B-17 AN-1 (100) DA-28 (100) Synthesis Example 37 B-18 AN-1 (70) AN-6 (30) DA-29 (100)

[Table 3] Polymer name acid derivatives diamine compounds Acid 1 (Morby) Acid 2 (Morby) Diamine 1 (Morbyl) Diamine-2 (Morbyl) Diamine-3 (Morbyl) Synthesis example 38 C-1 AN-1 (100) DA-32 (100) Synthesis Example 39 C-2 AN-1 (70) AN-3 (30) DA-32 (60) DA-30 (40) Synthesis Example 40 C-3 AN-1 (80) AN-6 (20) DA-33 (100) Synthesis Example 41 C-4 AN-1 (90) AN-3 (10) DA-33 (90) DA-30 (10) Synthesis Example 42 C-5 AN-2 (80) AN-3 (20) DA-34 (100) Synthesis Example 43 C-6 AN-3 (50) AN-4 (50) DA-34 (20) DA-30 (80) Synthesis Example 44 C-7 AN-4 (100) DA-35 (100) Synthesis Example 45 C-8 AN-4 (50) AN-5 (50) DA-36 (100) Synthesis Example 46 C-9 AN-5 (100) DA-37 (60) DA-41 (40) Synthesis Example 47 C-10 AN-5 (50) AN-7 (50) DA-38 (60) DA-30 (30) DA-18 (10) Synthesis Example 48 C-11 AN-6 (100) DA-39 (100) Synthesis Example 49 C-12 AN-7 (100) DA-40 (100) Synthesis example 50 C-13 AN-1 (100) DA-41 (50) DA-18 (50) Synthesis Example 51 C-14 AN-1 (70) AN-6 (30) DA-31 (100)

[Table 4] Polymer name acid derivatives diamine compounds Acid 1 (Morby) Acid 2 (Morby) Diamine 1 (Morbyl) Diamine-2 (Morbyl) Diamine-3 (Morbyl) Synthesis example 52 B-19 AN-1 (100) DA-42 (60) DA-30 (40) Synthesis example 53 B-20 AN-1 (70) AN-6 (30) DA-42 (40) DA-18 (60)

[Example 1] 1. Preparation of liquid crystal alignment film 20 parts by mass of polymer (A-1) obtained in Synthesis Example 1, 40 parts by mass of polymer (B-7) obtained in Synthesis Example 26, and 40 parts by mass of polymer (C-3) obtained in Synthesis Example 40 were diluted with NMP, γ-butyrolactone (GBL), butyl cellosolve (BC), diacetone alcohol (DAA), and diethylene glycol diethyl ether (DEDG) to obtain a solution with a solid content of 4.0% by mass and a solvent composition ratio of NMP:GBL:BC:DAA:DEDG = 30:30:20:10:10 (mass ratio). The solution was filtered using a filter with a pore size of 0.2 μm, thereby preparing the liquid crystal alignment agent (R-1).

2. Formation of a Liquid Crystal Alignment Film Based on Tribological Method A glass substrate with columnar spacers on the electrode forming surface and a non-electrode glass substrate is prepared, wherein a planar electrode (bottom electrode), an insulating layer, and a comb-shaped electrode (top electrode) are sequentially deposited on one side. A liquid crystal alignment agent (R-1) prepared in step 1 is applied to each surface of the pair of substrates using a rotary tool. The coating is pre-baked at 80°C for 1 minute and then dried in a 230°C oven with nitrogen replacement in the cavity for 30 minutes to form a coating with an average thickness of 0.1 μm. The coating surface was subjected to friction treatment using a friction machine with rollers wound with nylon fabric, at a roller speed of 1000 rpm, a platform movement speed of 3 cm/s, and a bristle indentation length of 0.3 mm. The friction-aligned coating was then ultrasonically cleaned in ultrapure water for 1 minute, followed by drying in a clean oven at 100°C for 10 minutes to form a liquid crystal alignment film.

3. Fabrication of FFS-type Liquid Crystal Display Element In the pair of substrates with liquid crystal alignment films fabricated in step 2, a liquid crystal main inlet is retained at the edge of the surface on which the liquid crystal alignment film is formed on one of the substrates. An epoxy resin adhesive containing aluminum oxide spheres with a diameter of 5.5 μm is screen-printed onto the substrates. The substrates are then overlapped and pressed together with their friction directions antiparallel, and the adhesive is thermo-cured at 150°C for 1 hour. Next, a negative nematic liquid crystal (manufactured by Merck, MLC-6608) is filled from the liquid crystal injection port into the space between the two substrates, and then the liquid crystal injection port is sealed using an epoxy-based adhesive. Furthermore, to eliminate flow alignment issues during liquid crystal injection, the substrate is heated to 120°C and then slowly cooled to room temperature. Next, polarizing plates are bonded to the outer two surfaces of the substrate to fabricate an FFS-type liquid crystal display element.

4. Evaluation of the sealant's adhesion (sealing performance) Similar to step 2, a pair of substrates with liquid crystal alignment films were fabricated using a liquid crystal alignment agent (R-1). Next, an epoxy resin adhesive containing 5.5 μm diameter aluminum oxide spheres was applied to the center portion of each alignment film forming surface of the pair of substrates. The substrates were then overlapped and pressed together with the alignment film forming surfaces facing each other, allowing the adhesive to harden and form a sealant. The pressure at which the sealant was peeled off was measured using a tensile testing machine. The condition where peeling occurs under a pressure of 2.0 kgf or more is defined as "Excellent," the condition where peeling occurs under a pressure of 1.0 kgf or more but less than 2.0 kgf is defined as "Good," and the condition where peeling occurs under a pressure of less than 1.0 kgf is defined as "Poor." The result, in the described embodiment, is an evaluation of "Excellent."

5. Evaluation of AC Residual Characteristics Except for the absence of polarizing plates bonded to the outer surfaces of the substrate, the same operation as described in 3. was performed to fabricate an FFS-type liquid crystal cell. For the FFS-type liquid crystal cell, after driving it at 10 V AC for 72 hours, the minimum relative transmittance (%) expressed by the following formula (2) was measured using a device with a polarizer and an analyzer positioned between the light source and the light quantity detector. Minimum relative transmittance (%) = [(β-B0)/(B100-B0)]×100 …(2) (In formula (2), B0 is the transmittance of light under blank and crossed nicols; B100 is the transmittance of light under blank and parallel nicols; β is the minimum transmittance of light under crossed nicols and sandwiched between the polarizer and analyzer.) The black level in the dark state is represented by the minimum relative transmittance of the liquid crystal cell. In FFS type liquid crystal cells, the smaller the black level in the dark state, the better the contrast. Cases with a minimum relative transmittance of less than 0.3% are rated "Excellent," those between 0.3% and 2.0% are rated "Good," and those above 2.0% are rated "Poor." The result, in this embodiment, is a "Good" rating.

6. Evaluation of DC Residual Image Characteristics For the liquid crystal display element manufactured in step 3, it is driven with AC 2.5 V and the brightness difference between any two pixels is set to 0. Then, it is driven with AC 2.5 V and only one pixel is driven with DC 1 V for 20 minutes to allow charge to accumulate. When the application of DC 1 V is stopped and driving is returned to AC 2.5 V, a brightness difference is generated between the two pixels due to the accumulated charge. The fading time of the residual DC value decay process is calculated by observing the change of the brightness difference over time. A softening time of less than 10 seconds is classified as "Excellent," a softening time of 10 seconds or more but less than 20 seconds is classified as "Good," and a softening time of 20 seconds or more is classified as "Poor." The result, in the described embodiment, is an "Excellent" rating.

7. Evaluation of Substrate Adhesion (Spacer Adhesion) For the liquid crystal display element manufactured in step 3, the alignment defects after applying external stress were observed. Specifically, a 5 mm diameter rod-shaped indenter was pressed for 10 minutes with an added weight of 2.0 kgf and a rotation speed of 200 rpm, and then the number of alignment defect sites causing light leakage within the pixels under the cross-nicotinic structure was counted. When the liquid crystal alignment film has high toughness, when the liquid crystal display element is pressed from top to the thickness direction, the liquid crystal alignment film deforms and returns to its original shape following the movement of the spacers in the thickness direction; therefore, the liquid crystal alignment film is not easily peeled off from the substrate. In this case, it can be said that the liquid crystal alignment film has good adhesion to the substrate. In contrast, when the toughness of the liquid crystal alignment film is insufficient, when the liquid crystal display element is pressed from top to thickness, the liquid crystal alignment film cannot follow the movement of the spacers. Cracks may form in the liquid crystal alignment film due to the pressure, making it easy to peel off from the substrate. In this case, the adhesion between the liquid crystal alignment film and the substrate can be considered poor. Therefore, in this embodiment, the adhesion between the liquid crystal alignment film and the substrate (especially the adhesion at the spacers) is evaluated by observing the alignment defects after applying external stress to the liquid crystal display element. Regarding the evaluation criteria, a case with 0 alignment defects is defined as "excellent," a case with 1 or more but less than 5 alignment defects is defined as "good," and a case with 5 or more alignment defects is defined as "poor." The result, in this embodiment, is a rating of "excellent".

8. Evaluation of Inkjet Coating Properties As a substrate for coating the liquid crystal alignment agent (R-1), a glass substrate with a transparent electrode containing ITO was used. This substrate was heated on a hot plate at 200°C for 1 minute, followed by UV/ozone cleaning to ensure the water contact angle on the transparent electrode surface was below 10°. The prepared liquid crystal alignment agent (R-1) was then coated onto the transparent electrode surface of the glass substrate using an inkjet coating machine (manufactured by Shibaura Mechatronics, Ltd.). The coating conditions were set to 2,500 strokes/(nozzle·min) and a spray volume of 250 mg/10 seconds for two round trips (a total of four strokes). After coating, the film was left to stand for 1 minute, then heated at 80°C to form a coating with an average thickness of 0.1 μm. The obtained coating was then visually inspected for the number of uneven areas and depressions under interference fringe gauge illumination (sodium lamp). A total of 0 uneven areas and depressions was rated "Excellent," 1 or more but less than 3 was rated "Good," and 3 or more was rated "Poor." As a result, the inkjet coating properties of the liquid crystal alignment agent in this embodiment were rated "Excellent."

[Examples 2-9, Examples 11-19, and Comparative Examples 1-9] The composition of the liquid crystal alignment agent was changed as shown in Table 5 below, but the liquid crystal alignment agent was prepared in the same manner as in Example 1. Furthermore, using the obtained liquid crystal alignment agent, a liquid crystal display element was manufactured in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 5 below. In Table 5, the resin in parentheses for each polymer indicates the mixing ratio (parts by mass) of each polymer relative to 100 parts by mass of the total polymer components used in the preparation of the liquid crystal alignment agent, based on the solid content.

[Example 10] Except for changing the composition of the liquid crystal alignment agent as shown in Table 5 below and using photoalignment instead of rubbing for the liquid crystal alignment film, the liquid crystal alignment agent was prepared in the same manner as in Example 1, and a liquid crystal display element and a liquid crystal cell were manufactured, and various evaluations were performed. The formation of the liquid crystal alignment film based on the photoalignment method was carried out according to the following procedure. (Formation of liquid crystal alignment film based on photoalignment method) On the surfaces of a glass substrate having a flat plate electrode (bottom electrode), an insulating layer and a comb-shaped electrode (top electrode) sequentially laminated on one side, and a glass substrate with columnar spacers on the electrode forming surface, and an opposing glass substrate without electrodes, the liquid crystal alignment agent was applied using a rotary tool and heated (pre-baked) on a hot plate at 80°C for 1 minute. Subsequently, the film was dried (post-baked) for 30 minutes in a 230°C oven after nitrogen replacement to form a coating with an average thickness of 0.1 μm. Photoalignment treatment was performed by irradiating the obtained coating with 1,000 J/ ^m² of ultraviolet light, including linearly polarized 254 nm bright rays, from the substrate normal direction using an Hg-Xe lamp. The irradiation amount was measured using a photometer based on a wavelength of 254 nm. The photoaligned coating was then heat-treated by heating it in a clean oven at 230°C for 30 minutes to form a liquid crystal alignment film. In addition, by varying the UV irradiation dose after baking within the range of 100 J/ ^m² to 10,000 J/ ^m² , three or more liquid crystal cells with different UV irradiation doses were manufactured. Using the liquid crystal cell with the exposure dose (optimal exposure dose) that showed the best alignment characteristics, various evaluations were performed in the same manner as in Example 1.

[Table 5] Liquid crystal alignment agent Evaluation Polymer [A] (mass ratio) Polymer [B] (mass ratio) Polymer [C] (mass ratio) Other polymers (mass ratio) Sealing and tightness AC residual image DC ghost image Partition tightness Paintability Implementation Example 1 A-1 (20) B-7 (40) C-3 (40) Excellent Excellent Excellent Excellent Excellent Implementation Example 2 A-2 (10) B-2 (70) C-7 (20) Excellent Excellent Excellent Excellent Excellent Implementation Example 3 A-3 (10) B-4 (45) C-6 (45) Excellent Excellent Excellent Excellent good Implementation Example 4 A-4 (30) B-5 (25) C-9 (45) Excellent Excellent Excellent good good Implementation Example 5 A-5 (15) B-3 (25) C-5 (60) Excellent Excellent Excellent Excellent Excellent Implementation Example 6 A-6 (20) B-16 (40) C-8 (40) good Excellent good good Excellent Implementation Example 7 A-7 (40) B-11 (30) C-11 (30) Excellent Excellent Excellent good Excellent Implementation Example 8 A-8 (10) B-14 (30) C-7 (60) Excellent Excellent Excellent Excellent Excellent Implementation Example 9 A-9 (50) B-8 (10) C-1 (40) Excellent Excellent Excellent Excellent Excellent Implementation Example 10 A-10 (5) B-10 (65) C-2 (30) Excellent Excellent good Excellent Excellent Implementation Example 11 A-11 (40) B-12 (30) C-12 (30) good Excellent Excellent good Excellent Implementation Example 12 A-12 (25) B-1 (45) C-10 (30) Excellent Excellent Excellent good Excellent Implementation Example 13 A-13 (5) B-9 (55) C-4 (40) Excellent Excellent Excellent Excellent Excellent Implementation Example 14 A-14 (20) B-15 (35) C-6 (45) Excellent Excellent good Excellent Excellent Implementation Example 15 A-15 (50) B-6 (40) C-7 (10) Excellent good Excellent Excellent Excellent Implementation Example 16 A-16 (30) B-13 (20) C-2 (50) Excellent good Excellent Excellent good Implementation Example 17 A-17 (40) B-2 (30) C-3 (30) good good Excellent Excellent Excellent Implementation Example 18 A-1 (20) B-19 (50) C-4 (30) Excellent Excellent good good Excellent Implementation Example 19 A-4 (10) B-20 (45) C-3 (45) Excellent good Excellent Excellent Excellent Comparative example 1 B-7 (50) C-3 (50) bad good Excellent Excellent Excellent Comparative example 2 B-7 (40) C-3 (40) A-18 (20) bad good Excellent Excellent Excellent Comparative example 3 B-7 (20) C-3 (30) A-19 (50) bad Excellent Excellent Excellent Excellent Comparative example 4 A-1 (20) C-3 (80) Excellent Excellent bad Excellent Excellent Comparative example 5 A-1 (20) C-3 (40) B-17 (40) Excellent Excellent bad Excellent Excellent Comparative example 6 A-1 (10) C-3 (20) B-18 (70) good good bad Excellent Excellent Comparative example 7 A-1 (20) B-7 (80) Excellent Excellent Excellent bad Excellent Comparative example 8 A-1 (20) B-7 (40) C-13 (40) Excellent Excellent Excellent bad Excellent Comparative example 9 A-1 (20) B-7 (30) C-14 (50) Excellent Excellent Excellent bad Excellent

As shown in Table 5, compared with Comparative Examples 1 to 9, the sealing performance, AC image retention characteristics, DC image retention characteristics, spacer fit, and coatability of Comparative Examples 1 to 19 were well improved in a balanced manner. In contrast, the sealing performance, DC image retention characteristics, and spacer fit of Comparative Examples 1 to 9, which do not contain any of polymers [A], [B], and [C], were rated as "poor".

without

Claims (10)

A liquid crystal alignment agent comprising: polymer [A] having a partial structure represented by formula (1) below and not having a partial structure represented by formula (2) below; polymer [B] having a partial structure represented by formula (2) below; and polymer [C] having a partial structure X in a main chain and not having a partial structure represented by formula (1) below and a partial structure represented by formula (2) below; Partial structure X: a structure represented by -( _CH2 ) _a- (where a is an integer from 2 to 20) or a structure in which any methylene group in the structure represented by -( _CH2 ) _a- is substituted with at least one group selected from the group consisting of ^-NR7- , ^-O- , -COO-, ^-NR7- CO-, -NR7-COO-, ^-NR8 -CO- ^NR9- and nitrogen-containing non-aromatic heterocyclic groups (where R ⁷ is a hydrogen atom or an alkyl group; ^R8 and ^R9 are each independently a hydrogen atom or an alkyl group, or represent a ring structure formed by the combination of ^R8 and ^R9 , the nitrogen atom bonded to ^R8 , the nitrogen atom bonded to ^R9 , and -CO-; in some structures X, ^-NR7- , -O-, -COO-, ^-NR7- CO-, ^-NR7 -COO-, ^-NR8 -CO- ^NR9- , and nitrogen-containing non-aromatic heterocyclic groups are not adjacent to each other). (In formula (1), ^R1 is tert-butoxycarbonyl, benzyloxycarbonyl, 1,1-dimethyl-2-halogenated ethoxycarbonyl, allyloxycarbonyl, 2-(trimethylsilyl)ethoxycarbonyl or 9-fluorenylmethoxycarbonyl; "*" indicates a bond). (In formula (2), ^A1 and ^A4 are each independently a divalent aromatic cyclic group; ^R2 and ^R3 are each independently a hydrogen atom or a monovalent organic group; ^B1 is a single bond, ^-NR4- , -O- or a divalent aromatic heterocyclic group; ^R4 is a hydrogen atom or a monovalent organic group; when ^B1 is a single bond, ^A2 is a divalent aromatic cyclic group, and ^A3 is a single bond or a divalent aromatic cyclic group; when ^B1 is a divalent aromatic heterocyclic group, ^A2 and ^A3 are each independently a single bond or a divalent aromatic cyclic group; when ^B1 is ^-NR4- or -O-, ^A2 and ^A3 are each independently a divalent aromatic cyclic group, or represent A The aromatic rings of ² and ^A3 are linked by a single bond or chain structure and together with ^-NR4- or -O- form a nitrogen- or oxygen-containing fused ring structure; "*" indicates a bond. The liquid crystal alignment agent as claimed in claim 1, wherein the polymer [A], the polymer [B] and the polymer [C] are at least one selected from the group consisting of polyamide, polyamide ester and polyimide. The liquid crystal alignment agent as described in claim 1 or claim 2, wherein the polymer [C] comprises a structural unit derived from a diamine represented by the following formula (3-1); (In formula (3-1), ^A5 is a divalent aromatic cyclic group; ^A6 is a single bond or a divalent aromatic cyclic group; ^Y2 is a divalent group having the aforementioned partial structure X; ^R5 is a hydrogen atom or a monovalent organic group). The liquid crystal alignment agent as described in claim 1 or claim 2, wherein the partial structure X has at least one base selected from the group consisting of -COO-, -NR ⁷ -CO-, -NR ⁷ -COO- and -NR ⁸ -CO-NR ^9- . The liquid crystal alignment agent as described in claim 1 or claim 2, wherein the polymer [A] comprises a structural unit derived from a diamine represented by the following formula (1-1); (In formula (1-1), ^A7 and ^A8 are each independently a divalent aromatic cycloalgide; ^Y1 is a divalent organic group; r is 0 or 1; wherein, when r is 1, at least one of ^A7 , ^A8 and ^Y1 has the partial structure represented by formula (1); when r is 0, ^A7 has the partial structure represented by formula (1).) The liquid crystal alignment agent as described in claim 1 or claim 2, wherein the polymer [A] has the following partial structure Y in the main chain: Partial structure Y: a structure represented by -( _CH2 ) _b- (where _b is an integer from 2 to 20) or a structure in which any methylene group in the structure represented by -( _CH2 )b- is substituted with at least one group selected from the group consisting of ^-NR10- , -O-, -COO-, ^-NR10 -CO-, ^-NR10 -COO-, ^{-NR10-CO-NR11- and} nitrogen-containing non-aromatic heterocyclic groups (wherein ^R10 and ^R11 are independently hydrogen atoms or monovalent organic groups; in partial structure Y, ^-NR10- , -O-, -COO-, -NR10-CO-, ^-NR10 -COO-, -NR10-COO-, -NR10-CO ^- NR1 ... ¹⁰ -CO-NR ^11- and nitrogen-containing non-aromatic heterocyclic groups are not adjacent to each other. The liquid crystal alignment agent as described in claim 1 or claim 2, wherein the polymer [B] comprises a structural unit derived from a diamine represented by the following formula (2-1); (In equation (2-1), ^A1 to ^A4 , ^B1 , ^R2 and ^R3 have the same meaning as in equation (2).) A liquid crystal alignment film formed from a liquid crystal alignment agent as described in any one of claims 1 to 7. A liquid crystal alignment film comprising: a polymer having a structural unit comprising a partial structure represented by formula (1A) in a portion different from the group participating in polymerization, and not having a partial structure represented by formula (2); a polymer having a partial structure represented by formula (2); and a polymer having a partial structure X in the main chain and not having a partial structure represented by formula (2); Partial structure X: a structure represented by - _{( CH2} ) _a- (where _a is an integer from 2 to 20) or a structure in which any methylene group is substituted by at least one group selected from the group consisting of ^-NR7- , ^-O- , -COO-, ^-NR7 -CO-, -NR7-COO-, ^-NR8 -CO- ^NR9- and nitrogen-containing non-aromatic heterocyclic groups (where ^R7 is a hydrogen atom or an alkyl group; R ^R8 and ^R9 are each independently a hydrogen atom or an alkyl group, or represent a ring structure formed by the combination of ^R8 and ^R9 , together with the nitrogen atom bonded to ^R8 , the nitrogen atom bonded to ^R9 , and -CO-; in some structures X, ^-NR7- , -O-, -COO-, -NR7-CO-, ^-NR7 -COO-, ^-NR8 - ^CO - ^NR9- , and nitrogen-containing non-aromatic heterocyclic groups are not adjacent to each other). (In formula (1A), "*" represents a key.) (In formula (2), ^A1 and ^A4 are each independently a divalent aromatic cyclic group; ^R2 and ^R3 are each independently a hydrogen atom or a monovalent organic group; ^B1 is a single bond, ^-NR4- , -O- or a divalent aromatic heterocyclic group; ^R4 is a hydrogen atom or a monovalent organic group; when ^B1 is a single bond, ^A2 is a divalent aromatic cyclic group, and ^A3 is a single bond or a divalent aromatic cyclic group; when ^B1 is a divalent aromatic heterocyclic group, ^A2 and ^A3 are each independently a single bond or a divalent aromatic cyclic group; when ^B1 is ^-NR4- or -O-, ^A2 and ^A3 are each independently a divalent aromatic cyclic group, or represent A The aromatic rings of ² and ^A3 are linked by a single bond or chain structure and together with ^-NR4- or -O- form a nitrogen- or oxygen-containing fused ring structure; "*" indicates a bond. A liquid crystal element comprising a liquid crystal alignment film as described in claim 8 or claim 9.