Liquid crystal alignment agents, liquid crystal alignment films, liquid crystal elements and polymers

Abstract

This invention provides a liquid crystal alignment agent that can form a liquid crystal alignment film with good liquid crystal alignment and excellent adhesion to the substrate, and can obtain a liquid crystal element whose quality degradation caused by external force is suppressed. The liquid crystal alignment agent contains a polymer [A] having a partial structure (a) represented by formula (1). In formula (1), A1, A2 and A3 are divalent aromatic ring groups. At least one of the divalent aromatic ring groups represented by A1 to A3 has a structure formed by the group represented by "-CH2OR1" bonded to the aromatic ring. B1 and B2 are divalent groups such as -O-, -S-, -NR2-, -CO-, -CO-O-, and -O-CO-.

Description

Technical Field

[0001] This invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, a liquid crystal element, and a polymer. Prior Technology

[0002] Previously, various driving methods were developed for liquid crystal elements, including different electrode structures and the physical properties of the liquid crystal molecules used. Examples include twisted nematic (TN) and super twisted nematic (STN) types, vertical alignment (VA) types, multi-domain vertical alignment (MVA) types, in-plane switching (IPS) types, fringe field switching (FFS) types, and optically compensated bending (OCB) types. These liquid crystal elements have liquid crystal alignment films used to align the liquid crystal molecules. Generally, the liquid crystal alignment film is formed by coating a liquid crystal alignment agent, obtained by dissolving or dispersing polymer components in an organic solvent, onto the surface of a substrate, preferably by heating.

[0003] In recent years, large-screen and high-resolution LCD TVs have become the mainstream. Furthermore, the widespread adoption of small display terminals such as smartphones and personal computers (PCs) has further increased the demand for high-quality LCD devices. To address these demands, various liquid crystal alignment agents have been proposed (see, for example, Patent Document 1 and Patent Document 2).

[0004] Patent Document 1 discloses a method in which a liquid crystal alignment agent contains polyimide or a polyimide precursor, as well as a crosslinking additive that is a low-molecular-weight compound to improve the hardness of the liquid crystal alignment film. Patent Document 2 discloses a method in which a liquid crystal alignment agent contains a polymer obtained from a diamine with a specific structure. [Existing Technical Documents] [Patent Literature]

[0005] [Patent Document 1] International Publication No. 2020 / 171128 [Patent Document 2] International Publication No. 2020 / 203110 Summary of the Invention

[0006] [The problem that the invention aims to solve] With the increasing precision and versatility of liquid crystal elements, the requirements for quality have become more stringent. For example, for liquid crystal elements, it is not only necessary to further improve the liquid crystal alignment and voltage retention rate, but also to ensure that the quality is not damaged by physical pressure such as vibration or tapping during transportation.

[0007] On the other hand, the demand for thinner designs in liquid crystal display (LCD) devices is accelerating, and the substrates (mainly glass substrates) for LCD devices are moving towards thinner films. Consequently, the stress applied to the interior of the liquid crystal element has increased compared to the past, leading to problems with initiation defects during pre-shipment impact tests, which take into account the increased stress in recent years. However, if only crosslinking additives are used as before, the film strength is insufficient, making it difficult to maintain quality.

[0008] Furthermore, in recent years, in mobile display devices such as smartphones and tablet computers (PCs), narrow bezels have been implemented to further expand the working area of ​​the touch panel while simultaneously miniaturizing the display device. One method for achieving narrow bezels is to form a liquid crystal alignment film on the entire surface of a substrate, then apply a sealant to the liquid crystal alignment film to bond the substrates together. However, when a sealant is applied to the liquid crystal alignment film, force can easily be applied to the portion of the liquid crystal alignment film with the sealant, leading to a tendency for the substrates to peel off. To prevent quality degradation due to physical pressure such as vibration or impact during transport, a high degree of adhesion between the liquid crystal alignment film and the substrate is required.

[0009] The present invention was made in view of the aforementioned issues, and its main objective is to provide a liquid crystal alignment agent that can form a liquid crystal alignment film with good liquid crystal alignment and excellent adhesion to the substrate, and to obtain a liquid crystal element whose quality degradation caused by external force is suppressed. [Methods for solving problems]

[0010] The inventors conducted diligent research to solve the aforementioned problem and discovered that it could be solved by using polymers with specific structures, thus completing the present invention. Specifically, the following means are provided according to the present invention.

[0011] <1> A liquid crystal alignment agent comprising a polymer [A] having a partial structure (a) represented by the following formula (1). [Chemistry 1] In formula (1), A1, A2, and A3 are each independently a divalent aromatic ring group. m is an integer from 0 to 2. When m is 0, at least one of the divalent aromatic ring groups represented by A1 and A3 has a structure formed by the group represented by "-CH2OR1" bonded to the aromatic ring. When m is 1 or 2, at least one of the divalent aromatic ring groups represented by A1, A2, and A3 has a structure formed by the group represented by "-CH2OR1" bonded to the aromatic ring. R1 is a hydrogen atom or a monovalent organic group. B1 and B2 are each independently -O-, -S-, -NR2-, -CO-, -CO-O-, -O-CO-, -CS-O-, -O-CS-, -NR2-CO-, -CO-NR2-, and -NR2-CO-NR. A divalent group consisting of a 3- or alkyldiyl group having 1 to 14 carbon atoms, or any methylene group having 2 to 14 carbon atoms substituted with at least one of -O-, -S-, -NR 2-, -CO-, -CO-O-, -O-CO-, -CS-O-, -O-CS-, -NR 2-CO-, -CO-NR 2-, and -NR 2-CO-NR 3-. R2 and R3 are independently hydrogen atoms or monovalent organogroups. When m is 2, the multiple A2 groups in the formula may be the same or different, and the multiple B2 groups may be the same or different. (* indicates a bond)

[0012] <2> A liquid crystal alignment film, which is used according to the... <1> It is formed by the liquid crystal alignment agent. <3> A liquid crystal element, comprising according to the... <2> The liquid crystal alignment film. <4> A polyamide, polyamide ester and polyimide having a partial structure represented by the formula (1). [The effects of the invention]

[0013] The liquid crystal alignment agent of the present invention can be used to form a liquid crystal alignment film with good liquid crystal alignment and excellent adhesion to the substrate. In addition, a liquid crystal element whose quality degradation is suppressed when subjected to external forces (such as vibration or impact) can be obtained. Implementation

[0014] "Liquid Crystal Alignment Agent" The following describes the components contained in the liquid crystal alignment agent of this disclosure, as well as other components that may be arbitrarily added as needed.

[0015] Furthermore, in this specification, the term "hydrocarbon group" encompasses chain-like hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. "Chain-like hydrocarbon group" refers to a straight-chain hydrocarbon group or branched hydrocarbon group whose main chain does not contain a ring structure and is composed solely of a chain structure. Chain-like hydrocarbon groups can be saturated or unsaturated. "Alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic hydrocarbon structure as its ring structure and does not contain an aromatic ring structure. Alicyclic hydrocarbon groups do not necessarily need to consist solely of an alicyclic hydrocarbon structure; they may also include groups with a chain structure in a portion of their structure. "Aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as its ring structure. Aromatic hydrocarbon groups do not necessarily need to consist solely of an aromatic ring structure; they may also contain a chain structure or an alicyclic hydrocarbon structure in a portion of their structure.

[0016] The term "main chain" refers to the longest "stem" portion of the polymer's atomic chain. Furthermore, the "stem" portion may contain ring structures. The term "side chain" refers to a branch that branches off from the polymer's "stem." "Aromatic ring" encompasses aromatic hydrocarbon rings and aromatic heterocycles. "Organic group" refers to an atomic group formed by removing any hydrogen atom from a carbon-containing compound (i.e., an organic compound). "Tetracarboxylic acid derivative" encompasses tetracarboxylic dianhydrides, tetracarboxylic acid diesters, and tetracarboxylic acid diester dihalides.

[0017] The liquid crystal alignment agent disclosed herein contains a polymer [A] having a partial structure (a) represented by the following formula (1). [Chemistry 2] In formula (1), A1, A2, and A3 are each independently a divalent aromatic ring group. m is an integer from 0 to 2. When m is 0, at least one of the divalent aromatic ring groups represented by A1 and A3 has a structure formed by the group represented by "-CH2OR1" bonded to the aromatic ring. When m is 1 or 2, at least one of the divalent aromatic ring groups represented by A1, A2, and A3 has a structure formed by the group represented by "-CH2OR1" bonded to the aromatic ring. R1 is a hydrogen atom or a monovalent organic group. B1 and B2 are each independently -O-, -S-, -NR2-, -CO-, -CO-O-, -O-CO-, -CS-O-, -O-CS-, -NR2-CO-, -CO-NR2-, and -NR2-CO-NR. A divalent group consisting of a 3- or alkyldiyl group having 1 to 14 carbon atoms, or any methylene group having 2 to 14 carbon atoms substituted with at least one of -O-, -S-, -NR 2-, -CO-, -CO-O-, -O-CO-, -CS-O-, -O-CS-, -NR 2-CO-, -CO-NR 2-, and -NR 2-CO-NR 3-. R2 and R3 are independently hydrogen atoms or monovalent organogroups. When m is 2, the multiple A2 groups in the formula may be the same or different, and the multiple B2 groups may be the same or different. (* indicates a bond)

[0018] <Polymer[A]> Regarding part of the structure (a) Partial structure (a) has two or more aromatic rings and includes a structure formed by a group represented by "-CH₂OR₁" bonded to at least one of the two or more aromatic rings (hereinafter also referred to as "specific aromatic ring structure"). Additionally, partial structure (a) also includes the specific aromatic ring structure and a spacer structure formed by the aromatic rings being linked to each other by specific divalent groups. By incorporating partial structure (a) containing the specific aromatic ring structure and the spacer structure into the polymer composition of a liquid crystal alignment film, a liquid crystal alignment film with high strength and excellent liquid crystal alignment properties can be obtained.

[0019] In formula (1), A1, A2, and A3 represent divalent aromatic ring groups, which are groups formed by removing any two hydrogen atoms from the ring portion of an aromatic ring. The aromatic ring contained in the divalent aromatic ring group can be an aromatic hydrocarbon ring or an aromatic heterocycle. Examples of aromatic hydrocarbon rings include: benzene ring, naphthalene ring, and anthracene ring. Examples of aromatic heterocycles include nitrogen-containing aromatic heterocycles, oxygen-containing aromatic heterocycles, and sulfur-containing aromatic heterocycles. Specific examples of aromatic heterocycles include: pyridine ring, pyrimidine ring, pyridazine ring, and pyrazine ring; examples of oxygen-containing aromatic heterocycles include: furan ring; and examples of sulfur-containing aromatic heterocycles include: thiophene ring.

[0020] From the viewpoint of achieving high density of liquid crystal alignment films and improving the strength and alignment properties of liquid crystal alignment films, the aromatic rings contained in A1, A2 and A3 are preferably benzene rings, naphthalene rings or pyridine rings, and more preferably benzene rings.

[0021] A specific aromatic ring structure is defined as a structure in which the group represented by "-CH2OR1" is bonded to at least one aromatic ring of the aromatic ring contained in the divalent aromatic ring group (A1 and A3 when m=0, and A1, A2, and A3 when m=1 or 2). That is, when m is 0, at least one of the two aromatic ring groups (A1 and A3) contained in the partial structure (a) has a structure formed by the group represented by "-CH2OR1" bonded to the aromatic ring. When m is 1, at least one of the three aromatic ring groups (A1, A2, and A3) contained in the partial structure (a) has a structure formed by the group represented by "-CH2OR1" bonded to the aromatic ring. When m is 2, at least any one of the four aromatic ring groups (one A1, two A2, and one A3) contained in partial structure (a) has a structure formed by the group represented by "-CH2OR1" bonded to the aromatic ring. From the viewpoint of ease of synthesis or liquid crystal alignment, m is preferably 0 or 1.

[0022] Examples of monovalent organic groups represented by R 1 include: monovalent hydrocarbon groups, and monovalent groups that are deactivated and replaced by hydrogen atoms through at least one of heat and light (hereinafter also referred to as "deactivated groups"). Specific examples of monovalent hydrocarbon groups include: alkyl groups having 1 to 6 carbon atoms, cycloalkyl groups having 4 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, and aralkyl groups having 6 to 10 carbon atoms. Among these, alkyl groups having 1 to 3 carbon atoms and phenyl groups are preferred, and alkyl groups having 1 to 3 carbon atoms are more preferred.

[0023] The monovalent degradable group is preferably a group that is degraded by heat (preferably heating during film formation) (hereinafter also referred to as "thermally degradable group"). Specific examples of thermally degradable groups include: aminocarbamate degradable groups such as tributoxycarbonyl (Boc group), benzyloxycarbonyl, 1,1-dimethyl-2-haloethyloxycarbonyl, allyloxycarbonyl, and 2-(trimethylsilyl)ethoxycarbonyl; ether degradable groups such as alkyl, benzyl, and p-methoxybenzyl with 1 to 7 carbon atoms; acetal degradable groups such as methoxymethyl, ethoxyethyl, and 2-tetrahydropyranyl; acetyl degradable groups such as acetyl and benzoyl; allyl degradable groups such as allyl and methylallyl; and silyl ether degradable groups such as trimethylsilyl, triethylsilyl, and tributyldimethylsilyl. From the viewpoint of achieving both heat-induced ease of release and storage stability, these are preferably carbamate-based release groups, ether-based protecting groups, acetal-based protecting groups, or acetyl groups, and more preferably terbutoxycarbonyl, alkyl groups with 1 to 3 carbon atoms, 2-tetrahydropyranyl, methoxymethyl, 1-ethoxyethyl, or acetyl groups.

[0024] Wherein, R1 is preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a monovalent thermally detachable group, more preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a third butoxycarbonyl group, a 2-tetrahydropyranyl group, a methoxymethyl group, a 1-ethoxyethyl group, or an acetyl group.

[0025] From the viewpoint of achieving a good balance between improved film strength and good liquid crystal alignment, the number of "-CH 2OR 1" in each partial structure (a) is preferably 1 to 4, more preferably 1 or 2. Furthermore, in a specific aromatic ring structure, the number of "-CH 2OR 1" bonds to one aromatic ring is preferably 1 or 2.

[0026] Furthermore, the aromatic rings contained in A1, A2, and A3 may also have substituents other than the group represented by "-CH2OR1" (hereinafter also referred to as "other substituents"). Examples of other substituents include: alkyl groups having 1 to 3 carbon atoms, alkoxy groups having 1 to 3 carbon atoms, halogen atoms, hydrogen atoms, cyano groups, etc. From the viewpoint of promoting the crosslinking reaction of the group represented by "-CH2OR1" and obtaining a liquid crystal alignment film with sufficiently high film strength, the number of other substituents in the aromatic rings contained in A1, A2, and A3 is preferably 0 to 2 per aromatic ring, more preferably 0 or 1, and even more preferably 0 (i.e., no other substituents).

[0027] B1 and B2 are divalent groups (hereinafter also referred to as "divalent group E1") formed by substituting any methylene group from -O-, -S-, -NR 2-, -CO-, -CO-O-, -O-CO-, -CS-O-, -O-CS-, -NR 2-CO-, -CO-NR 2-, -NR 2-CO-NR 3- or an alkyldiyl group having 1 to 14 carbon atoms, or any methylene group having 2 to 14 carbon atoms by substitution of at least one of the groups (hereinafter also referred to as "specific heteroatom-containing groups") from -O-, -S-, -NR 2-, -CO-, -CO-O-, -O-CO-, -CS-O-, -O-CS-, -NR 2-CO-, -CO-NR 2- and -NR 2-CO-NR 3-. B1 and B2 may be the same as each other or different.

[0028] The alkyldiyl groups with 1 to 14 carbon atoms represented by B1 and B2 can be either linear or branched. From the viewpoint of forming a liquid crystal alignment film with good liquid crystal alignment, the alkyldiyl groups represented by B1 and B2 are preferably linear. From the viewpoint of liquid crystal alignment, linear alkyldiyl groups with 1 to 10 carbon atoms are preferred, linear alkyldiyl groups with 2 to 10 carbon atoms are more preferred, and linear alkyldiyl groups with 4 to 10 carbon atoms are even more preferred.

[0029] As the monovalent organic groups represented by R2 and R3, examples include monovalent hydrocarbon groups and decoupling groups. Specific examples of monovalent hydrocarbon groups can be illustrated by the examples and preferred examples of the monovalent hydrocarbon group represented by R1. The monovalent decoupling group is preferably a thermally decoupling group. Specifically, it is preferably a tributoxycarbonyl, 9-fluorenylmethyloxycarbonyl, and especially preferably a tributoxycarbonyl (Boc group). R2 and R3 are preferably hydrogen atoms, alkyl groups having 1 to 3 carbon atoms, or monovalent thermally decoupling groups, more preferably hydrogen atoms, alkyl groups having 1 to 3 carbon atoms, or tributoxycarbonyl, and even more preferably hydrogen atoms or tributoxycarbonyl.

[0030] Regarding the aspect of enabling good alignment of the liquid crystal, the divalent group E1 represented by B1 and B2 is preferably a group formed by substituting any methylene group in a straight-chain alkyl diester with the specific heteroatom-containing group. In this case, regarding the aspect of improving the film strength, the specific heteroatom-containing group is preferably an electron-donating group (-O-, -S-, -NR 2-, *-O-CO-, *-O-CS-, *-NR 2-CO-, -NR 2-CO-NR 3- (where "*" indicates a bond with an aromatic ring)).

[0031] For the divalent group E1, when the divalent aromatic ring group (A1, A2, or A3) adjacent to group E1 has a structure formed by bonding an aromatic ring to a group represented by "-CH2OR1", it is preferable to bond the aromatic ring to the group represented by "-CH2OR1" through -O-, -S-, -NR2-, -CO-, -CO-O-, -O-CO-, -CS-O-, -O-CS-, -NR2-CO-, -CO-NR2-, or -NR2-CO-NR3-. Direct bonding of these groups to a specific aromatic ring structure is preferred in terms of obtaining a liquid crystal alignment film with good adhesion to the substrate, and in terms of improving the effect of suppressing display quality degradation caused by vibration or impact.

[0032] The divalent base E1 is preferably the base represented by the following formula (G-1). [Chemistry 3] (In formula (G-1), X1 and X2 are independently -O-, -S-, -NR 2-, -CO-, -CO-O-, -O-CO-, -CS-O-, -O-CS-, -NR 2-CO-, -CO-NR 2-, or -NR 2-CO-NR 3-. R4 is an alkyldiyl group with 1 to 6 carbon atoms. n is 1 or 2. R2 and R3 have the same meaning as in formula (1). "*" indicates a bond.)

[0033] In formula (G-1), from the viewpoint of maintaining liquid crystal alignment and obtaining a liquid crystal alignment film with high improvement effect on film strength, X1 and X2 are preferably -O-, -S-, -NR 2-, *-O-CO-, *-O-CS-, *-NR 2-CO-, -NR 2-CO-NR 3- (where "*" indicates a bond with the aromatic ring), and more preferably -O-, -S- or -NR 2-.

[0034] In terms of forming an organic film exhibiting good liquid crystal alignment, B1 and B2 are preferably alkyldiyl or divalent E1 with 1 to 14 carbon atoms. Furthermore, in terms of improving film strength while maintaining good liquid crystal alignment, B1 and B2 are more preferably divalent E1, and even more preferably groups represented by formula (G-1).

[0035] As a specific example of part of structure (a), the structures represented by equations (1-1) to (1-29) can be listed below. [Chemistry 4] [Chemistry 5]

[0036] [Chemistry 6]

[0037] [Chemistry 7] (In the formula, "*" represents a bond)

[0038] Polymer [A] may have a partial structure (a) in the main chain or in the side chain. From the viewpoint of improving the liquid crystal alignment and film strength of the liquid crystal alignment film by introducing the partial structure (a), polymer [A] is preferably a partial structure (a) in the main chain. Furthermore, when polymer [A] "has a partial structure (a) in the main chain", it includes not only the case where polymer [A] has a partial structure (a) only in the main chain, but also the case where it has a partial structure (a) in both the main chain and the side chain.

[0039] From the viewpoint of obtaining a liquid crystal element exhibiting good liquid crystal alignment and high adhesion in polymer [A], the content ratio of partial structure (a) is preferably 2 mol% or more relative to the total amount of monomer units in polymer [A]. From this viewpoint, the content ratio of partial structure (a) is more preferably 5 mol% or more, and even more preferably 7 mol% or more, relative to the total amount of monomer units in polymer [A]. Furthermore, the content ratio of partial structure (a) can be appropriately set according to the main chain of polymer [A], and is, for example, 60 mol% or less, preferably 50 mol% or less relative to the total amount of monomer units in polymer [A]. Moreover, in polymer [A], partial structure (a) may be only one type, or it may be two or more types.

[0040] The main framework of polymer [A] is not particularly limited. In terms of forming a liquid crystal alignment film with high affinity for liquid crystal and high mechanical strength and reliability, and in terms of easily incorporating part of structure (a) into the polymer backbone, polymer [A] is preferably at least one selected from the group consisting of polyamide, polyamide ester and polyimide.

[0041] The method for manufacturing polymer [A] is not particularly limited as long as a portion of structure (a) can be introduced into the polymer. Regarding the ease of introducing a portion of structure (a) into the polymer, polymer [A] is preferably manufactured by polymerization using a monomer having a portion of structure (a). Regarding the ability to form a liquid crystal alignment film with high affinity for liquid crystals and high mechanical strength, and regarding the high degree of freedom in monomer design, the monomer having a portion of structure (a) is preferably a diamine compound having a portion of structure (a) (hereinafter also referred to as "specific diamine").

[0042] (Specific diamine) The specific diamine is any compound having part of structure (a) and two primary amino groups; there are no particular limitations on the other parts of the structure. Specifically, the specific diamine is preferably a compound represented by the following formula (2). [Chemistry 8] (In equation (2), D1 and D2 are independently single bonds or divalent organic groups, respectively. A1, A2, A3, B1, B2 and m have the same meaning as in equation (1))

[0043] In formula (2), the divalent organic groups represented by D1 and D2 can be listed as: chain hydrocarbon groups, alicyclic hydrocarbon groups, aromatic hydrocarbon groups, and nitrogen-containing heterocyclic groups, etc. Among these, the divalent organic groups represented by D1 and D2 are preferably aromatic hydrocarbon groups and nitrogen-containing heterocyclic groups, and more preferably substituted or unsubstituted phenyl groups. Among substituted phenyl groups, the substituents can be listed as: alkyl groups with 1 to 5 carbon atoms, alkoxy groups with 1 to 5 carbon atoms, halogen atoms, etc. D1 and D2 are preferably single bonds, substituted or unsubstituted phenyl groups, or substituted or unsubstituted pyridyl groups, and more preferably substituted or unsubstituted phenyl groups.

[0044] Furthermore, regarding specific and preferred examples of A1, A2, A3, B1, B2 and m, the explanation of formula (1) is applied.

[0045] In the case where the primary amine group (more specifically, the primary amine group involved in polymerization) is bonded to the aromatic ring contained in a specific aromatic ring structure, the group represented by "-CH 2OR 1" is preferably located in the ortho or meta position relative to the primary amine group, and is more preferably located in the meta position in order to further improve the film strength.

[0046] Specific examples of a particular diamine include compounds represented by formulas (3-1) to (3-29) respectively. [Chemistry 9] [Chemistry 10]

[0047] [Chemistry 11] [Chemistry 12]

[0048] [Chemistry 13]

[0049] Polyamide In the case where polymer [A] is polyamide, the polyamide (hereinafter also referred to as "polyamide [A]") can be obtained, for example, by reacting a tetracarboxylic dianhydride with a diamine compound containing a specific diamine.

[0050] (Tetracarboxylic acid dianhydride) In the synthesis of polyacrylic acid [A], one tetracarboxylic dianhydride can be used alone, or two or more can be used in combination. Examples of tetracarboxylic dianhydrides used in the synthesis of polyacrylic acid [A] include aliphatic tetracarboxylic dianhydrides and aromatic tetracarboxylic dianhydrides. Aliphatic tetracarboxylic dianhydrides include chain tetracarboxylic dianhydrides and alicyclic tetracarboxylic dianhydrides.

[0051] Specific examples of tetracarboxylic dianhydrides include: 1,2,3,4-butanetetracarboxylic dianhydride, ethylenediaminetetraacetic acid dianhydride, etc. Alicyclic tetracarboxylic dianhydrides include: 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, 5-(2,5-dioxo[1,2-c]furan-1,3-dione, etc. Tetrahydrofuran-3-yl)-8-methyl-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 2,4,6,8-tetracarboxylic bicyclo[3.3.0]octane-2:4,6:8-dianhydride, cyclopentanetetracarboxylic dianhydride, cyclohexanetetracarboxylic dianhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornene-2:3,5:6-dianhydride, etc.

[0052] Examples of aromatic tetracarboxylic dianhydrides include: pyromellitic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, ethylene glycol dipreptyltrioxide ester, 4,4'-carbonyldiphthalic anhydride, and 3,3',4,4'-biphenyltetracarboxylic dianhydride. Furthermore, in the synthesis of polyacrylic acid [A], the tetracarboxylic dianhydride described in Japanese Patent Application Publication No. 2010-97188 can also be used as the tetracarboxylic dianhydride.

[0053] In terms of obtaining a liquid crystal alignment film with high solubility and exhibiting good liquid crystal alignment and electrical properties, the tetracarboxylic dianhydride used in the synthesis of polyacrylic acid [A] preferably contains aliphatic tetracarboxylic dianhydride, more preferably alicyclic tetracarboxylic dianhydride. The amount 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].

[0054] (Diamine compounds) In the synthesis of polyacrylic acid [A], one diamine compound may be used alone, or two or more may be used in combination. The diamine compound used in the synthesis of polyacrylic acid [A] may be only a specific diamine, or may include diamine compounds that do not possess part of structure (a) (hereinafter also referred to as "other diamines"). Examples of other diamines include, for example, aliphatic diamines, aromatic diamines, and diaminoorganosiloxanes. Aliphatic diamines include chain diamines and alicyclic diamines.

[0055] Specific examples of other diamines include: chain diamines such as meta-xylylenediamine and hexamethylenediamine; alicyclic diamines such as 1,4-diaminocyclohexane and 4,4'-methylenebis(cyclohexylamine); and diaminoorganosiloxanes such as 1,3-bis(3-aminopropyl)-tetramethyldisiloxane.

[0056] Aromatic diamines include: p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4-aminophenyl-4-aminobenzoate, 4,4'-diaminoazobenzene, 3,5-diaminobenzoic acid, 1,5-bis(4-aminophenoxy)pentane, 1,2-bis(4-aminophenoxy)ethane, 1,3-bis(4-aminophenoxy)propane, 1,6-bis(4-aminophenoxy)hexane, 6,6'-(pentamethylenedioxy)bis(3-aminopyridine), N,N'-di(5-amino-2-pyridyl)-N,N'-di(tert-butoxycarbonyl)ethylenediamine, and bis[2-(4-aminophenyl)ethyl]adipic acid. 4,4'-Diaminodiphenyl ether, 4,4'-Diaminodiphenylamine, 4,4'-Diaminodiphenylethylurea, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 4,4'-(diisopropylphenylene)bisaniline, 2,6-diaminopyrimidine, 2,4-diaminopyrimidine, 3,6-diaminopyrazole, N-methyl-3,6-diaminopyrazole, 3,6-diaminoacridine, monomers containing a diphenylamine structure, and the following formula (F-1). [Chemistry 14] (In formula (F-1), R21 and R22 are each independently an alkyldiyl group. R23 is a hydrogen atom, an alkyl group with 1 to 3 carbon atoms, or a dehydrogenated group. r1 is an integer from 1 to 3. When r1 is 2 or 3, multiple R22s may be the same or different from each other, and multiple R23s may be the same or different from each other.) The compounds represented are main-chain diamines; Hexadecyloxy-2,4-diaminobenzene, octadecyloxy-2,4-diaminobenzene, octadecyloxy-2,5-diaminobenzene, cholesteryloxy-3,5-diaminobenzene, cholesteryloxy-3,5-diaminobenzene, cholesteryloxy-2,4-diaminobenzene, cholesteryloxy-2,4-diaminobenzene, cholesteryl 3,5-diaminobenzoate, cholesteryl 3,5-diaminobenzoate, 3,5- Lanostane diaminobenzoate, 3,6-bis(4-aminobenzoyloxy)cholestan, 3,6-bis(4-aminophenoxy)cholestan, 4-(4'-trifluoromethoxybenzoyloxy)cyclohexyl-3,5-diaminobenzoate, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-butylcyclohexane, 3,5-diaminobenzoic acid =5ξ-cholestan-3-yl, and the following formula (E-1) [Chemistry 15] (In formula (E-1), XI and XII are independently single bonds, -O-, *-COO-, or *-OCO- (where "*" indicates a bond with XI). RI is an alkyldiyl group with 1 to 3 carbon atoms. RII is a single bond or an alkyldiyl group with 1 to 3 carbon atoms. RIII is an alkyl, alkoxy, fluoroalkyl, or fluoroalkoxy group with 1 to 20 carbon atoms. a is 0 or 1. b is an integer from 0 to 3. c is an integer from 0 to 2. d is 0 or 1. Where 1 ≦ a + b + c ≦ 3) The compounds represented are side-chain diamines, etc.

[0057] As a compound represented by formula (F-1), examples include compounds represented by formulas (F-1-1) to (F-1-3) below. As a compound represented by formula (E-1), examples include compounds represented by formulas (E-1-1) to (E-1-4) below. As other diamines, one or more can be used alone or in combination. [Chemistry 16]

[0058] When manufacturing polyamide [A], the amount of a specific diamine used is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more, relative to the total amount of diamine compound used in the synthesis of polyamide [A].

[0059] (Synthesis of polyamides) Polyamide [A] can be obtained by reacting a tetracarboxylic dianhydride and a diamine compound with a molecular weight modifier as needed.

[0060] In the synthesis reaction of polyacrylic acid [A], the preferred ratio of tetracarboxylic dianhydride to diamine compound is 0.2 to 2 equivalents relative to the amino group of diamine compound. Examples of molecular weight modifiers include: maleic anhydride, phthalic anhydride, itaconic anhydride, etc.; monoamine compounds such as aniline, cyclohexylamine, n-butylamine, etc.; and monoisocyanate compounds such as phenyl isocyanate, naphthyl isocyanate, etc. The preferred ratio of molecular weight modifier to the total 100 parts by mass of tetracarboxylic dianhydride and diamine compound used is 20 parts by mass or less.

[0061] The synthesis reaction of polyacrylic acid [A] 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 for the reaction include: aprotic polar solvents, phenolic solvents, alcoholic solvents, ketone solvents, ester solvents, ether solvents, halogenated hydrocarbons, and hydrocarbons. Among these, it is preferred to use one or more solvents selected from the group consisting of N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphoric acid triamine, m-cresol, xylenol, and halogenated phenols, or a mixture of one or more of these solvents with other organic solvents (e.g., butyl cellosolve, diethylene glycol diethyl ether, etc.). The amount of organic solvent used is preferably set to be 0.1% to 50% by mass relative to the total amount of the reaction solution, while the total amount of tetracarboxylic acid dianhydride and diamine compound is 0.1% to 50% by mass.

[0062] A polymer solution obtained by dissolving polyacrylic acid [A] can be obtained in the manner described above. The polymer solution can be used directly for the preparation of liquid crystal alignment agents, or it can be used for the preparation of liquid crystal alignment agents after separating the polyacrylic acid [A] contained in the polymer solution.

[0063] <Polyamide> When polymer [A] is a polyamide, the polyamide (hereinafter also referred to as "polyamide [A]") can be obtained, for example, by the following methods: [I] reacting polyamide [A] with an esterifying agent; [II] reacting a tetracarboxylic acid diester with a diamine compound containing a specific diamine; [III] reacting a tetracarboxylic acid diester dihalide with a diamine compound containing a specific diamine. Polyamide [A] may have only an amide structure, or it may be a partial esterification in which both an amide structure and an amide structure coexist. The reaction solution obtained by dissolving polyamide [A] can be directly used in the preparation of a liquid crystal alignment agent, or it can be used in the preparation of a liquid crystal alignment agent after separating the polyamide [A] contained in the reaction solution.

[0064] <Polyimide> When polymer [A] is a polyimide, the polyimide (hereinafter also referred to as "polyimide [A]") can be obtained, for example, by dehydrating and cyclizing polyacrylic acid [A] synthesized in the manner described above, followed by amide imidization. Polyimide [A] can be a fully amide imidized product formed by completely dehydrating and cyclizing the amide structure of polyacrylic acid [A], which is its precursor, or a partially amide imidized product formed by dehydrating and cyclizing only a portion of the amide structure, resulting in the coexistence of the amide structure and the amide ring structure. Polyimide [A] preferably has an amide imidization rate of 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 polyamide. Here, a portion of the amide ring may be an isoamide ring.

[0065] The dehydration and ring-closure of polyacrylic acid [A] is preferably carried out by the following method: dissolving polyacrylic acid [A] in an organic solvent, adding a dehydrating agent and a dehydration and ring-closure 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 dehydrating agents. The amount of dehydrating agent used is preferably 0.01 mol to 20 mol relative to 1 mol of the polyacrylic acid structure of polyacrylic acid [A]. Tertiary amines such as pyridine, trimethylpyridine, dimethylpyridine, and triethylamine can be used as dehydration and ring-closure catalysts. The amount of dehydration and ring-closure catalyst used is preferably 0.01 mol to 10 mol relative to 1 mol of the dehydrating agent used. Examples of organic solvents used in the dehydration and ring-closure reaction include those used in the synthesis of polyacrylic acid [A]. The reaction temperature for the dehydration and ring-closure reaction is preferably 0°C to 180°C. The reaction time is preferably 1.0 hour to 120 hours. Furthermore, the reaction solution containing polyimide [A] can be used directly for the preparation of liquid crystal alignment agents, or the polyimide [A] can be separated and used for the preparation of liquid crystal alignment agents.

[0066] When polymer [A] is at least one selected from the group consisting of polyamide, polyamide ester, and polyimide, the solution viscosity of polymer [A] is preferably 10 mPa·s to 800 mPa·s when preparing a 10% by mass solution, more preferably 15 mPa·s to 500 mPa·s. Furthermore, the solution viscosity (mPa·s) is a 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 polymer [A] (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

[0067] The weight-average molecular weight (Mw) of polymer [A], determined by gel permeation chromatography (GPC) based on polystyrene, 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 determined by GPC, is preferably 7 or less, more preferably 5 or less. Moreover, when preparing the liquid crystal alignment agent, polymer [A] can be used alone or in combination with two or more polymers.

[0068] Relative to 100 parts by mass of solid components (total components other than the solvent in the liquid crystal alignment agent) contained in the liquid crystal alignment agent, the content of polymer [A] in the liquid crystal alignment agent is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more. When the content of polymer [A] is within the aforementioned range, it is suitable in terms of sufficiently obtaining improved film strength, adhesion to the substrate, and liquid crystal alignment.

[0069] <Other Ingredients> In addition to polymer [A], liquid crystal alignment agents may also contain components different from polymer [A] (hereinafter also referred to as "other components") as needed.

[0070] (Polymer[Q]) The liquid crystal alignment agent disclosed herein may further contain a polymer (hereinafter also referred to as "polymer [Q]") that does not have part of structure (a) as a polymer component.

[0071] The main framework of polymer [Q] is not particularly limited. Examples of polymer [Q] include: polyamide, polyamide ester, polyimide, polyorganosiloxane, polyester, polyenamine, polyurea, polyamide, polyamide-imide, polybenzoxazole precursor, polybenzoxazole, cellulose derivative, polyacetal, addition polymer, etc. From the viewpoint of obtaining a highly reliable liquid crystal element, polymer [Q] is preferably selected from at least one group consisting of polyamide, polyamide ester, polyimide, polyorganosiloxane, and addition polymer. Examples of addition polymers include: (meth)acrylic acid polymers, styrene polymers, maleimide polymers, and styrene-maleimide copolymers, etc.

[0072] When the liquid crystal alignment agent disclosed herein contains both polymer [A] and polymer [Q], the content of polymer [Q] is preferably 1% by mass or more, more preferably 2% by mass or more, relative to the total amount of polymer [A] and polymer [Q]. Furthermore, the content of polymer [Q] is preferably 95% by mass or less, more preferably 90% by mass or less, relative to the total amount of polymer [A] and polymer [Q]. Polymer [Q] can be used alone or in combination of two or more.

[0073] (solvent) The liquid crystal alignment agent disclosed herein is prepared as a liquid composition in which the polymer component and other components used as needed are preferably dispersed or dissolved in a suitable solvent.

[0074] Organic solvents are preferably used. Specific examples include: N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,2-dimethyl-2-imidazolinone, 1,3-dimethyl-2-imidazolinone, phenol, γ-butyrolactone, γ-butyrolactone, 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 cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisoamyl ether, ethylene carbonate, propylene carbonate, propylene glycol monomethyl ether (PGME), diethylene glycol diethyl ether acetate, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol diacetate, cyclopentanone, cyclohexanone, etc. As a solvent, it can be used alone or in combination with two or more.

[0075] Other components included in the liquid crystal alignment agent, besides those mentioned above, include, for example, crosslinking agents, antioxidants, metal chelate compounds, curing accelerators, surfactants, fillers, dispersants, and photosensitizers. The proportions of these other components can be selected appropriately for each compound without compromising the effects of this disclosure.

[0076] The concentration of solid components in the liquid crystal alignment agent (the ratio of the total mass of components other than the solvent in the liquid crystal alignment agent to the total mass of the liquid crystal alignment agent) is appropriately selected considering factors such as viscosity and volatility, and is preferably in the range of 1% to 10% by mass. If the solid component concentration is 1% by mass or more, the film thickness of the coating can be sufficiently ensured, and a liquid crystal alignment film exhibiting better liquid crystal alignment properties can be obtained, which is suitable in this respect. On the other hand, if the solid component concentration is 10% by mass or less, there is a tendency that the coating can be set to an appropriate thickness, a liquid crystal alignment film exhibiting good liquid crystal alignment properties can be easily obtained, and the viscosity of the liquid crystal alignment agent becomes moderate, resulting in good coatability.

[0077] Here, by using a liquid crystal alignment agent containing polymer [A], it is possible to obtain a liquid crystal element with improved liquid crystal alignment and adhesion to the substrate, high film strength, and suppressed quality degradation due to external forces. The reason for this is not yet clear, but as a reason, it is believed that because polymer [A] has a specific aromatic ring structure, the polymers can easily crosslink with each other at a high density through heating during film formation, for example, via "-CH₂OR₁", thereby obtaining a liquid crystal alignment film that suppresses film breakage. Furthermore, it is envisioned that polymer [A] can be crosslinked through condensation reactions with the electron-rich aromatic rings of a portion of structure (a), addition reactions with carboxylic acids, or exchange reactions with esters. In addition, it is believed that because the aromatic rings of polymer [A] are linked to each other through spacer structures, it has high film strength and exhibits good liquid crystal alignment. These speculations do not limit this disclosure.

[0078] Liquid crystal alignment films and liquid crystal elements The liquid crystal alignment film disclosed herein can be manufactured using a liquid crystal alignment agent prepared in the manner 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, STN type, VA type (including VA-MVA type, VA-Patterned Vertical Alignment (PVA) type, IPS (In-Plane Switching) type, FFS (Fringe Field Switching) type, Optically Compensated Bend (OCB) type, and Polymer Sustained Alignment (PSA) type. The liquid crystal element can be manufactured, for example, by a method including steps 1 to 3. The substrate used in step 1 varies depending on the desired operating mode. Steps 2 and 3 are common in all operating modes.

[0079] <Step 1: Coating Formation> First, a liquid crystal alignment agent is coated onto a substrate, preferably by heating the coated surface to form a coating film on the substrate. Examples of substrates that can be used include: float glass, soda glass, etc.; and transparent substrates containing plastics such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, and poly(alicyclic olefins). When manufacturing TN, STN, or VA type liquid crystal elements, two substrates with patterned transparent conductive films are used. Conversely, when manufacturing IPS or FFS type liquid crystal elements, a substrate with patterned comb-shaped electrodes and an opposing substrate without electrodes are used. As transparent conductive films, NESA films (a registered trademark of PPG Industries, Inc.) containing tin oxide (SnO2) and indium tin oxide (ITO) films containing indium oxide-tin oxide (In2O3-SnO2) can be used.

[0080] There are no particular limitations on the method for coating a liquid crystal alignment agent onto a substrate. The coating of the liquid crystal alignment agent onto the substrate can be performed by methods such as spin coating, printing (e.g., offset printing, flexographic printing), inkjet printing, slot coating, bar coating, extrusion die coating, direct gravure coating, chamber doctor coating, offset gravure coating, impregnation coating, and MB coating.

[0081] After coating the liquid crystal alignment agent, preheating (pre-baking) is preferably performed to prevent sagging of the coated 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. Then, the solvent is completely removed, and a calcination (post-baking) step is performed as needed for the purpose of thermally imidizing the acetic acid structure present in the polymer. The calcination temperature (post-baking temperature) at this time 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 thickness of the formed film is preferably 0.001 μm to 1 μm.

[0082] <Step 2: Orientation Treatment> When manufacturing TN, STN, IPS, or FFS type liquid crystal elements, an alignment process (alignment treatment) is performed to impart liquid crystal alignment capability to the coating film formed in step 1. This imparts the alignment capability of the liquid crystal molecules to the coating film, forming a liquid crystal alignment film. Preferably, the alignment treatment involves rubbing the surface of the coating film formed on the substrate with cotton or nylon, or photoalignment treatment by irradiating the coating film with light to impart liquid crystal alignment capability. When manufacturing vertically aligned liquid crystal elements, the coating film formed in step 1 can be used directly as a liquid crystal alignment film; however, alignment treatment can also be performed on the coating film to further improve the liquid crystal alignment capability.

[0083] Light irradiation for photoalignment can be performed by methods such as: irradiating the coating after the post-baking step; irradiating the coating after the pre-baking step and before the post-baking step; or irradiating the coating during heating in at least one of the pre-baking and post-baking steps. As the radiation irradiating the coating, for example, ultraviolet light and visible light containing wavelengths of 150 nm to 800 nm can be used. Ultraviolet light containing wavelengths of 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. For unpolarized radiation, the irradiation direction is set to an oblique direction.

[0084] 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 cellosolve, ethyl lactate, etc.), or a mixture thereof, or the substrate may be heated.

[0085] <Step 3: Construction of Liquid Crystal Cells> In this step, two substrates with liquid crystal alignment films are prepared, and a liquid crystal cell is manufactured by placing liquid crystal between the two substrates facing each other. Methods for manufacturing the liquid crystal cell include: placing the two substrates facing each other with the 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 surfaces and the sealant and sealing the injection hole; and using a liquid crystal drop fill (ODF) method. As a sealant, epoxy resin containing a hardener and alumina spheres as spacers can be used, for example. As a liquid crystal, nematic liquid crystal and smectic liquid crystal can be used, with nematic liquid crystal being preferred.

[0086] In the PSA mode, the following process is performed: a polymeric compound (e.g., a polyfunctional (meth)acrylate compound, etc.) is filled into the intercellular spaces along with the liquid crystal, and after the liquid crystal cells are constructed, the liquid crystal cells are irradiated with light while a voltage is applied between the conductive films of a pair of substrates. When manufacturing a PSA mode liquid crystal element, the proportion of the polymeric compound used is 0.01 to 3 parts by mass relative to 100 parts by mass of the total liquid crystal, preferably 0.1 to 1 part by mass.

[0087] In the manufacture of a liquid crystal display device, a polarizing plate is then attached to the outer surface of the liquid crystal cell. Examples of polarizing plates include: a polarizing plate made by sandwiching a polarizing film called an "H film" (one side of which is extended and aligned with polyvinyl alcohol and the other side absorbs iodine) with a cellulose acetate protective film, or a polarizing plate that includes the H film itself.

[0088] The liquid crystal element disclosed herein can be effectively applied to a variety of uses. Specifically, it can be used as a display device or dimming device, phase retardation film, for example, in clocks, portable game consoles, word processors, computers (laptops and desktops), car navigation systems, camcorders, personal digital assistants (PDAs), digital cameras, mobile phones, smartphones, various monitors, LCD TVs, information displays, and other display devices.

[0089] The following means are provided by the above detailed description of this disclosure. [Means 1] A liquid crystal alignment agent comprising a polymer [A] having a partial structure (a) represented by the formula (1). [Method 2] According to the liquid crystal alignment agent of Method 1, wherein in the formula (1), B1 and B2, the groups adjacent to the divalent aromatic ring group having a structure formed by the group represented by "-CH2OR1" bonded to the aromatic ring bonded by the group represented by "-CH2OR1" are bonded by -O-, -S-, -NR2-, -CO-, -CO-O-, -O-CO-, -CS-O-, -O-CS-, -NR2-CO-, -CO-NR2- or -NR2-CO-NR3-. [Method 3] The liquid crystal alignment agent according to Method 1 or Method 2, wherein the polymer [A] comprises a structural unit derived from a diamine having the partial structure (a). [Method 4] The liquid crystal alignment agent according to Method 3, wherein the diamine is a compound represented by Formula (2). [Method 5] A liquid crystal alignment agent according to any one of means 1 to means 4, wherein the polymer [A] is at least one selected from the group consisting of polyamide, polyamide ester and polyimide. [Method 6] The liquid crystal alignment agent according to any one of Method 1 to Method 5 further comprises a polymer [Q] that does not have the said partial structure (a). [Method 7] The liquid crystal alignment agent according to Method 6, wherein the polymer [Q] is at least one selected from the group consisting of polyamide, polyamide ester, polyimide, polyorganosiloxane and addition polymer. [Method 8] A liquid crystal alignment film is formed using a liquid crystal alignment agent according to any one of Methods 1 to 7. [Method 9] A liquid crystal element comprising a liquid crystal alignment film according to Method 8. [Means 10] A polymer, which is a polyamide, a polyamide ester or a polyimide, having a partial structure represented by the formula (1).

[0090] [Example] The following describes the implementation methods in more detail based on the embodiments, but the invention is not to be construed as limited by the following embodiments.

[0091] In the following examples, the amide content of polyimide in the polymer solution was determined by the following method. [Imidification rate of polyimide] The polyimide solution was added to pure water, and the resulting precipitate was dried under reduced pressure at room temperature. It was then dissolved in deuterated dimethyl silane, and 1H nuclear magnetic resonance (NMR) was performed at room temperature using tetramethylsilane as a reference. The propylene enrichment rate [%] was calculated from the obtained 1H-NMR spectrum using the following equation (1). Acrylimide rate [%] = (1 - (A1 / (A2×α))) × 100 ···(1) (In equation (1), A1 is the peak area of ​​protons originating from NH groups that appear near a chemical shift of 10 ppm, A2 is the peak area of ​​protons originating from other protons, and α is the ratio of the number of other protons to the number of one proton of NH groups in the polymer precursor (polyacrylic acid))

[0092] The required amounts of the raw material compounds and polymers used in the following examples are ensured by repeating the synthesis at the scale shown in the following synthesis examples as needed. Furthermore, unless otherwise specified, "parts" and "%" in the examples and comparative examples refer to mass.

[0093] The abbreviation for the compound is as described below. Furthermore, the compound represented by formula (X) will sometimes be simply referred to as "compound (X)".

[0094] (Tetracarboxylic acid dianhydride) [Chemistry 17]

[0095] (Diamine compounds) [Chemistry 18] [Chemistry 19]

[0096] [Chemistry 20] [Chemistry 21] [Chemistry 22]

[0097] (Other compounds) [Chemistry 23]

[0098] <Polymer Synthesis> 1. Synthesis of polyacrylic acid [Synthesis example 1] 100 moles of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (compound (b-1)) as a tetracarboxylic dianhydride and 100 moles of compound (DA-1) as a diamine compound were dissolved in N-methyl-2-pyrrolidone (NMP) and reacted at room temperature for 6 hours to obtain a solution containing 15% by mass of polyamide (designated as polymer (PAA-1)).

[0099] [Synthesis Example 2~Synthesis Example 27] Except for changing the types and amounts of tetracarboxylic dianhydrides and diamine compounds used as described in Table 1, the same procedures as in Synthesis Example 1 were performed to obtain polyamides (polymers (PAA-2) to (PAA-19) and polymers (PAA-1) to (PAA-8)). Furthermore, in Table 1, the values ​​for tetracarboxylic dianhydrides (dianhydride 1 to dianhydride 3) represent the proportion (molar ratio) of each compound relative to the total amount of tetracarboxylic dianhydrides used in the synthesis of polyamides. The values ​​for diamine compounds (diamine 1 to diamine 4) represent the proportion (molar ratio) of each compound relative to the total amount of diamine compounds used in the synthesis of polyamides.

[0100] [Table 1] Polymer Name Acid dianhydride 1 acid dianhydride 2 acid dianhydride 3 Diamine 1 Diamine 2 Diamine 3 Diamine 4 type Mörby type Mörby type Mörby type Mörby type Mörby type Mörby type Mörby Synthesis example 1 PAA-1 b-1 100 DA-1 100 Synthesis example 2 PAA-2 b-1 100 DA-2 100 Synthesis example 3 PAA-3 b-1 100 DA-3 100 Synthesis example 4 PAA-4 b-1 100 DA-4 100 Synthesis example 5 PAA-5 b-1 100 DA-5 100 Synthesis example 6 PAA-6 b-1 100 DA-6 100 Synthesis Example 7 PAA-7 b-1 100 DA-7 100 Synthesis Example 8 PAA-8 b-1 100 DA-8 100 Synthesis Example 9 PAA-9 b-1 100 DA-9 100 Synthesis Example 10 PAA-10 b-1 100 DA-10 100 Synthesis example 11 PAA-11 b-1 100 DA-11 100 Synthesis example 12 PAA-12 b-1 100 DA-12 100 Synthesis example 13 PAA-13 b-5 95 b-3 5 DA-2 50 a-1 50 Synthesis example 14 PAA-14 b-1 5 b-3 35 B-4 60 DA-2 30 a-2 40 a-3 10 a-4 20 Synthesis Example 15 PAA-15 b-1 40 B-4 60 DA-8 30 a-5 50 a-6 20 Synthesis Example 16 PAA-16 b-1 95 b-3 5 DA-9 30 a-7 50 a-8 20 Synthesis Example 17 PAA-17 b-1 5 b-3 35 B-4 60 DA-4 30 a-9 10 a-10 20 a-4 40 Synthesis Example 18 PAA-18 b-2 100 DA-4 30 a-11 50 a-4 20 Synthesis example 19 PAA-19 b-1 100 DA-8 20 a-1 20 a-12 30 a-13 30 Synthesis example 20 paa-1 b-1 100 a-14 100 Synthesis Example 21 paa-2 b-1 100 a-18 100 Synthesis example 22 paa-3 b-1 100 a-19 100 Synthesis example 23 paa-4 b-1 100 a-20 50 a-3 50 Synthesis example 24 paa-5 b-1 5 b-3 35 b-4 60 a-4 90 a-10 10 Synthesis example 25 paa-6 b-2 100 a-11 50 a-4 50 Synthesis Example 26 paa-7 b-1 100 a-1 20 a-12 30 a-13 50 Synthesis Example 27 paa-8 b-6 100 a-5 20 a-6 80

[0101] 2. Synthesis of polyimide [Synthesis Example 28] 100 moles of compound (b-2) as a tetracarboxylic dianhydride, 20 moles of compound (DA-2) as a diamine compound, 50 moles of compound (a-11), and 30 moles of compound (a-4) were dissolved in NMP and reacted at room temperature for 6 hours to obtain a solution containing 15% by mass of polyacrylic acid. Subsequently, NMP was added to the obtained polyacrylic acid solution to prepare a solution with a polyacrylic acid concentration of 10% by mass. Pyridine and acetic anhydride were then added, and a dehydration and ring-closure reaction was carried out at 60°C for 4 hours. After the dehydration and ring-closure reaction, the solvent in the system was replaced with fresh NMP to obtain a solution containing 15% by mass of polyimide with a amide content of approximately 80% (designated as polymer (PI-1)).

[0102] [Synthesis Example 29~Synthesis Example 39] Except for changing the types and amounts of tetracarboxylic dianhydrides and diamine compounds used as described in Table 2, the same procedures as in Synthesis Example 28 were performed to obtain polyimides (polymers (PI-2) to (PI-9) and polymers (PI-1) to (PI-3)). Furthermore, in Table 2, the values ​​of diamine compounds (diamine 1 to diamine 4) represent the proportion (molar ratio) of each compound relative to the total amount of diamine compounds used in the synthesis of polyimides.

[0103] [Table 2] Polymer Name Acid dianhydride 1 Diamine 1 Diamine 2 Diamine 3 Diamine 4 type Mörby type Mörby type Mörby type Mörby type Mörby Synthesis example 28 PI-1 b-2 100 DA-2 20 a-11 50 a-4 30 Synthesis Example 29 PI-2 b-2 100 DA-4 30 a-11 50 a-4 20 Synthesis Example 30 PI-3 b-2 100 DA-8 30 a-14 40 a-15 20 a-7 10 Synthesis Example 31 PI-4 b-2 100 DA-9 20 a-12 50 a-4 30 Synthesis Example 32 PI-5 b-2 100 DA-10 20 a-11 50 a-4 20 a-13 10 Synthesis Example 33 PI-6 b-1 100 DA-2 20 a-1 20 a'11 30 a-13 30 Synthesis Example 34 PI-7 b-3 100 DA-2 15 a-16 20 a-9 35 a-17 30 Synthesis Example 35 PI-8 b-2 100 DA-13 30 a'11 50 a-4 20 Synthesis Example 36 PI-9 b-2 100 DA-14 30 a'11 50 a-4 20 Synthesis Example 37 pi-1 b-2 100 a'11 50 a-4 50 Synthesis example 38 pi-2 b-1 100 a-1 20 a-12 30 a-13 50 Synthesis Example 39 pi-3 b-3 100 a-16 20 a-9 50 a-17 30

[0104] 3. Synthesis of Polyorganosiloxanes [Synthesis Example 40] 100.0 g of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (compound (S-1)), 500 g of methyl isobutyl ketone, and 10.0 g of triethylamine were added to a 1000 ml three-necked flask and mixed at room temperature. Then, 100 g of deionized water was added dropwise over 30 minutes using a self-dropping funnel, and the mixture was refluxed and reacted at 80°C for 6 hours. After the reaction was complete, the organic layer was removed and washed with a 0.2% (w / w) ammonium nitrate aqueous solution until the washing water was neutral. The solvent and water were then removed by distillation under reduced pressure. An appropriate amount of methyl isobutyl ketone was added to obtain a 50% (w / w) solution of an epoxy-containing polyorganosiloxane polymer (ESSQ-1). To a 500 ml three-necked flask, add 3.10 g of compound (c-1) (containing 20 moles of epoxy groups relative to polymer (ESSQ-1)), 3.24 g of compound (c-2) (containing 10 moles of epoxy groups relative to polymer (ESSQ-1)), 1.00 g of tetrabutylammonium bromide, 20.0 g of a solution containing polymer (ESSQ-1), and 290.0 g of methyl isobutyl ketone, and stir at 90 °C for 18 hours. After cooling to room temperature, perform 10 separate washing operations using distilled water. Then, recover the organic layer, and after repeating the concentration and NMP dilution twice using a rotary evaporator, adjust the NMP concentration to 10% by mass using NMP to obtain an NMP solution of the polyorganosiloxane (designated as polymer (PSQ-1)).

[0105] 4. Synthesis of styrene-maleimide copolymers [Synthesis Example 41] Under nitrogen, 5.00 g of compound (M-1), 1.05 g of compound (M-2), 4.80 g of compound (M-3), and 2.26 g of compound (M-4) as monomers, 0.39 g of 2,2'-azobis(2,4-dimethylpentanilide) as a free radical polymerization initiator, 0.39 g of 2,4-diphenyl-4-methyl-1-pentene as a chain transfer agent, and 52.5 ml of N-methyl-2-pyrrolidone (NMP) as a solvent were added to a 100 mL two-necked flask, and polymerization was carried out at 70 °C for 6 hours. After reprecipitation in methanol, the precipitate was filtered and dried under vacuum at room temperature for 8 hours to obtain the target polymer (designated as polymer (MI-1)).

[0106] <Preparation and Evaluation of Liquid Crystal Alignment Agents> [Example 1: Optical FFS type liquid crystal display element] 1. Preparation of liquid crystal alignment agents The solution containing 90 parts by mass of polymer (PAA-1) obtained in Synthesis Example 1 and the solution containing 10 parts by mass of polymer (pi-1) obtained in Synthesis Example 35 were mixed and diluted with NMP and butyl cellosolve (BC) to prepare a solution with a solvent composition of NMP / BC = 80 / 20 (mass ratio) and a solid content concentration of 3.5% by mass. The solution was filtered using a filter with a pore size of 0.2 μm to prepare the liquid crystal alignment agent (AL-1).

[0107] 2. Manufacturing of FFS-type liquid crystal display elements using photoalignment method A planar electrode (bottom electrode), an insulating layer, and a comb-shaped electrode (top electrode) are sequentially stacked on a single-sided glass substrate (designated as the first substrate), and a glass substrate without electrodes (designated as the second substrate). Then, a liquid crystal alignment agent (AL-1) is applied to the electrode forming surface of the first substrate and one of the substrate surfaces of the second substrate using a spinner, and heated (pre-baked) for 1 minute using a hot plate at 80°C. Next, it is dried (post-baked) for 30 minutes in a 230°C oven where nitrogen replacement has been performed, forming a coating with an average thickness of 0.1 μm. Photoalignment treatment is performed by irradiating the resulting coating with 1,000 J / m² of ultraviolet light containing a linearly polarized 254 nm bright line from the substrate normal direction using an Hg-Xe lamp. Furthermore, the irradiation amount is measured using a photometer with a wavelength of 254 nm as the reference. Subsequently, the coating that has undergone photo-alignment treatment is heat-treated by heating it in a clean oven at 230°C for 30 minutes to form a liquid crystal alignment film. Next, for one of the pair of substrates with the liquid crystal alignment film, an epoxy resin adhesive containing alumina spheres with a diameter of 3.5 μm is applied to the outer edge of the surface with the liquid crystal alignment film by screen printing. Then, the substrates are overlapped and pressed together so that the projection direction of the polarization axis on the substrate surface during light irradiation is antiparallel, and the adhesive is thermosetting at 150°C for 1 hour. Subsequently, negative liquid crystal (manufactured by Merck, MLC-6608) is filled between the pair of substrates through the liquid crystal injection port, and the liquid crystal injection port is sealed with an epoxy adhesive to obtain a liquid crystal cell. Furthermore, in order to remove the flow alignment during liquid crystal injection, it is heated at 120°C and then slowly cooled to room temperature. Furthermore, by performing the aforementioned series of operations by varying the UV irradiation amount after baking within the range of 100 J / m² to 10,000 J / m², three or more liquid crystal cells with different UV irradiation amounts were manufactured. The liquid crystal cell exhibiting the best alignment characteristics (optimal exposure amount) was used for the following evaluations of liquid crystal alignment, initial VHR, VHR reliability, and film strength.

[0108] 3. Evaluation of liquid crystal alignment The liquid crystal cells manufactured in step 2 were left to stand for 500 hours under a high-brightness backlight of 27,000 cd / m². The liquid crystal alignment was evaluated based on the rate of change in retardation before and after backlight illumination. First, for the liquid crystal display element manufactured in step 2, the retardation was measured using an Axoscan sensor manufactured by Opto Science. The rate of change in retardation α before and after backlight illumination was calculated using the following formula (z-1). It can be said that the smaller the rate of change α, the better the liquid crystal alignment. Cases with a rate of change α of less than 1% were designated as "good (○)", cases with a rate of change α greater than 1% but less than 2% were designated as "acceptable (△)", and cases with a rate of change α greater than 2% were designated as "poor (×)". α = Δθ / θ1 ···(z-1) (In equation (z-1), Δθ represents the delay difference before and after irradiation, and θ1 represents the delay value before irradiation.) As a result, the liquid crystal alignment of the embodiment was evaluated as "acceptable (△)".

[0109] 4. Evaluation of substrate adhesion Liquid crystal alignment agent (AL-1) was coated onto a glass substrate using a spinner. After pre-baking on an 80°C hot plate for 2 minutes, the substrate was heated for 30 minutes in a 230°C oven (after nitrogen purging) to form a coating with an average thickness of 0.10 μm. This process was repeated to create two coated glass substrates. On one coated glass substrate, an ODF sealant (manufactured by Sekisui Chemicals, S-WB42) was applied with a width of 1 mm, and the substrates were bonded together with the ODF sealant in contact with the coating of the other glass substrate. The substrates were then irradiated with a metal halide lamp at 30,000 J / m² (converted to 365 nm) and heated in a 120°C oven for 1 hour. After heating, the adhesion strength was measured using a tensile and compression testing machine (model: SDWS-0201-100SL) from Imada Manufacturing Co., Ltd., to evaluate the adhesion between the film and the substrate. Regarding the evaluation, a contact strength of 200 N / cm² or higher is designated as "Good (○)", a contact strength of 100 N / cm² or higher but less than 200 N / cm² is designated as "Acceptable (△)", and a contact strength less than 100 N / cm² is designated as "Poor (×)". As a result, in the described embodiment, the contact strength is 204 N / cm², which is an evaluation of "Good (○)" for contact performance.

[0110] 5. Evaluation of membrane strength (abrasion resistance) The liquid crystal alignment agent (AL-1) prepared in step 1 was coated onto a glass substrate using a rotator and heated (pre-baked) for 3 minutes using a hot plate at 110°C. Then, it was dried (post-baked) for 30 minutes in an oven at 230°C where nitrogen replacement had been performed, forming a coating with an average thickness of 0.08 μm. The haze value of the coating was measured using a haze meter. Subsequently, the coating was subjected to five rubbing treatments using a rubbing machine with a roller wound with cotton cloth, at a roller speed of 1000 rpm, a stage movement speed of 3 cm / s, and a bristle indentation length of 0.3 mm. The haze value of the liquid crystal alignment film was then measured using a haze meter, and the difference between the haze value and the haze value before the rubbing treatment (haze change value) was calculated. With the haze value of the film before the rubbing treatment set as Hz1 (%) and the haze value of the film after the rubbing treatment set as Hz2 (%), the haze change value is expressed by the following formula (z-2). Haze change (%) = Hz2 - Hz1 ···(z-2) A haze change value of less than 1.0 for the liquid crystal alignment film is evaluated as "Good (○)", a haze change value of 1.0 or more but less than 1.5 is evaluated as "Acceptable (△)", and a haze change value greater than 1.5 is evaluated as "Poor (×)". If the haze change value is less than 1.5 (more preferably less than 1.0), it can be said that the film strength is sufficiently high and the abrasion resistance is high, that is, the mechanical properties of the film are good. As a result, the film strength in the above embodiment is evaluated as "Good (○)".

[0111] 6. Evaluation of membrane strength (button resistance test) For the liquid crystal cell manufactured in section 2, its resistance to button testing was evaluated. The evaluation was conducted as follows: First, the liquid crystal cell was observed under orthogonal Nicol microscopes with polarizing light, and the number of bright spots was counted. Second, the liquid crystal cell was fixed on a mounting plate, and a button bar was moved up and down to repeatedly apply a load to the liquid crystal cell. The load was set to 250 gf, the number of repetitions was set to 100,000, and the speed was set to 10 Hz / sec. After the button was pressed, the liquid crystal cell was observed again, and the number of bright spots was counted. If the difference in the number of bright spots before and after the button press was less than 10, it was evaluated as "good (○)"; if it was more than 10 but less than 50, it was evaluated as "acceptable (△)"; and if it was more than 50, it was evaluated as "unacceptable (×)". If the difference in the number of bright spots was less than 50 (more preferably less than 10), it could be said that the film had good mechanical strength against the button. As a result, the film strength was evaluated as "good (○)" in the above embodiment.

[0112] [Examples 2-28 and Comparative Examples 1-6] Except for changing the composition of the liquid crystal alignment agent as shown in Table 3, the liquid crystal alignment agent was prepared in the same manner as in Example 1. Furthermore, using the obtained liquid crystal alignment agent, FFS-type liquid crystal cells were manufactured by photoalignment in the same manner as in Example 1, and various evaluations were performed. These results are shown in Table 3. In addition, in Examples 26, 5, and 6, N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane (designated as compound (N-1)) was formulated as an additive component along with the polymer components. In Table 3, the values ​​in the mass ratio column represent the proportion (parts by mass) of each compound (polymer, additive) based on solid components relative to 100 parts by mass of the total polymer components used in the preparation of the liquid crystal alignment agent.

[0113] [Table 3] Orientation agent composition Characteristic evaluation as an alignment agent Polymer 1 Polymer 2 additive Orientation Tightness membrane strength abrasion resistance membrane strength Key resistance test type mass ratio type mass ratio type mass ratio Example 1 AL-1 PAA-1 90 pi-1 10 △ ○ ○ ○ Example 2 AL-2 PAA-2 90 pi-1 10 ○ ○ ○ ○ Example 3 AL-3 PAA-3 90 pi-1 10 ○ ○ ○ △ Example 4 AL-4 PAA-4 90 pi-1 10 ○ ○ ○ ○ Example 5 AL-5 PAA-5 90 pi-1 10 ○ ○ ○ ○ Example 6 AL-6 PAA-6 90 pi-1 10 ○ ○ ○ △ Example 7 AL-7 PAA-7 90 pi-1 10 ○ ○ ○ △ Example 8 AL-8 PAA-8 90 pi-1 10 ○ ○ ○ ○ Example 9 AL-9 PAA-9 90 pi-1 10 ○ ○ ○ ○ Example 10 AL-10 PAA-10 90 pi-1 10 ○ ○ ○ ○ Example 11 AL-11 PAA-11 90 pi-1 10 ○ ○ ○ ○ Example 12 AL-12 PAA-12 90 pi-1 10 △ ○ ○ ○ Example 13 AL-13 PAA-13 90 pi-1 10 ○ ○ ○ ○ Example 14 AL-14 PAA-14 90 pi-1 10 ○ ○ ○ ○ Example 15 AL-15 PAA-15 70 pi-1 30 ○ ○ ○ ○ Example 16 AL-16 PAA-16 70 pi-1 30 ○ ○ ○ ○ Example 17 AL-17 PAA-17 90 pi-1 10 ○ ○ ○ ○ Example 18 AL-18 PAA-18 30 paa-4 70 ○ ○ ○ ○ Example 19 AL-19 PI-1 10 paa-4 90 ○ ○ ○ ○ Example 20 AL-20 PI-2 10 paa-5 90 ○ ○ ○ ○ Example 21 AL-21 PI-3 10 paa-5 90 ○ ○ ○ ○ Example 22 AL-22 PI-4 10 paa-1 90 ○ ○ ○ ○ Example 23 AL-23 PI-5 10 paa-1 90 ○ ○ ○ ○ Example 24 AL-24 PI-1 20 PAA-14 80 ○ ○ ○ ○ Example 25 AL-25 PI-2 20 PAA-13 80 ○ ○ ○ ○ Example 26 AL-26 PAA-2 90 pi-1 10 N-1 10 △ ○ ○ ○ Example 27 AL-27 PI-8 20 paa-8 80 ○ ○ ○ ○ Example 28 AL-28 PI-9 20 paa-5 80 ○ ○ ○ ○ Comparative Example 1 AL-29 paa-1 90 pi-1 10 ○ × △ × Comparative Example 2 AL-30 paa-2 90 pi-1 10 ○ ○ ○ × Comparative Example 3 AL-31 paa-3 90 pi-1 10 △ × △ × Comparative Example 4 AL-32 paa-6 30 paa-4 70 ○ × △ × Comparative Example 5 AL-33 paa-1 90 pi-1 10 N-1 10 △ △ ○ × Comparative Example 6 AL-34 paa-1 90 pi-1 10 N-1 20 × ○ ○ ○

[0114] As shown in Table 3, Examples 1 to 28, which used liquid crystal alignment agents containing polymer [A] having partial structure (a), showed good results in terms of film strength (especially resistance to key tests) compared to Comparative Examples 1 to 5, which used liquid crystal alignment agents without polymer [A]. A balance was achieved in film strength, liquid crystal alignment, and adhesion to the substrate. However, regarding Comparative Example 6, which increased the amount of a low-molecular-weight compound (N-1) with crosslinking groups in the alignment agent composition of Comparative Example 5, although film strength and adhesion were good, the liquid crystal alignment was poor.

[0115] In Examples 1 to 28, where polymers containing alkylene chains with two or more carbon atoms in partial structure (a) were used (Examples 2 to 11, 13 to 25, 27, and 28), the liquid crystal alignment was rated as "Good (○)," indicating that the film adhesion and film strength (abrasion resistance) could be improved while maintaining the liquid crystal alignment. Furthermore, in examples where polymers with B1 and B2 in partial structure (a) being -O- or -NR2- were used (Examples 1, 2, 4, 5, and 8 to 28), the film strength (button resistance) was rated as "Good (○)," which is even better.

[0116] [Example 29: Frictional FFS Type Liquid Crystal Display Element] 1. Preparation of liquid crystal alignment agents The solution of the polymer (PAA-4) obtained in Synthesis Example 4 was diluted with NMP and butyl cellosolve (BC) to prepare a solution with a solvent composition of NMP / BC = 80 / 20 (mass ratio) and a solid content of 3.5% by mass. The solution was then filtered using a filter with a pore size of 0.2 μm to prepare the liquid crystal alignment agent (AL-35).

[0117] 2. Manufacturing of FFS-type liquid crystal display elements using the triboelectric method A first substrate (with a flat plate electrode, bottom electrode), an insulating layer, and a comb-shaped electrode (top electrode) are sequentially stacked on a single-sided glass substrate, and a second substrate (without electrodes). A liquid crystal alignment agent (AL-35) is then applied to the electrode forming surface of the first substrate and a single-sided surface of the second substrate using a spinner, and pre-baked at 110°C for 3 minutes. Afterward, the substrate is dried for 30 minutes in a 230°C oven with nitrogen purging, resulting in a coating with an average thickness of 0.08 μm. The coating surface is then rubbed using a friction machine with rollers wound with rayon fabric at a roller speed of 1000 rpm, a stage movement speed of 3 cm / s, and a bristle indentation length of 0.3 mm. Finally, the substrate is ultrasonically cleaned in ultrapure water for 1 minute, and then dried in a 100°C clean oven for 10 minutes, thereby obtaining a pair of substrates with a liquid crystal alignment film. Subsequently, for a pair of substrates with a liquid crystal alignment film, a liquid crystal injection port remains at the edge of the surface where the liquid crystal alignment film is formed. An epoxy resin adhesive containing alumina spheres with a diameter of 3.5 μm is then screen-printed onto the port. The substrates are then overlapped and pressed together, and the adhesive is thermosetting at 150°C for 1 hour. Next, negative liquid crystal (Merck, MLC-6608) is filled into the gap between the two substrates through the injection port, and the injection port is sealed with an epoxy adhesive. Furthermore, to remove the flow alignment during liquid crystal injection, the liquid crystal is heated at 120°C and then slowly cooled to room temperature to manufacture a liquid crystal cell. Moreover, when the pair of substrates are overlapped, the friction method of each substrate is antiparallel.

[0118] 3. Evaluation For the liquid crystal cell manufactured in step 2, the liquid crystal alignment was evaluated using the same method as in Example 1. Additionally, the adhesion and film strength were evaluated using a liquid crystal alignment agent (AL-35) in the same manner as in Example 1. The evaluation results are shown in Table 4.

[0119] [Examples 30-39 and Comparative Examples 7-11] Except for changing the composition of the liquid crystal alignment agent as shown in Table 4, the liquid crystal alignment agent was prepared in the same manner as in Example 29. Furthermore, using the obtained liquid crystal alignment agent, FFS-type liquid crystal cells were manufactured by the triboelectric method in the same manner as in Example 29, and various evaluations were performed. These results are shown in Table 4. Moreover, in Examples 31-37, Example 39, and Comparative Examples 10 and 11, two polymers were used as polymer components. In Table 4, the values ​​in the mass ratio column represent the mixing ratio (parts by mass) of each compound (polymer, additive) based on solid components relative to 100 parts by mass of the total polymer components used in the preparation of the liquid crystal alignment agent.

[0120] [Table 4] Orientation agent composition Characteristic evaluation as an alignment agent Polymer 1 Polymer 2 additive Orientation Tightness membrane strength abrasion resistance membrane strength Key resistance test type mass ratio type mass ratio type mass ratio Example 29 AL-35 PAA-4 100 ○ ○ ○ ○ Example 30 AL-36 PAA-10 100 ○ ○ ○ ○ Example 31 AL-37 PAA-2 70 paa-7 30 ○ ○ ○ ○ Example 32 AL-38 PAA-4 70 paa-7 30 ○ ○ ○ ○ Example 33 AL-39 PAA-13 70 paa-7 30 ○ ○ ○ ○ Example 34 AL-40 PAA-14 70 paa-7 30 ○ ○ ○ ○ Example 35 AL-41 PAA-15 70 paa-7 30 ○ ○ ○ ○ Example 36 AL-42 PAA-19 70 paa-7 30 ○ ○ ○ ○ Example 37 AL-43 PAA-4 70 pi-2 30 ○ ○ ○ ○ Example 38 AL-44 PI-6 100 ○ ○ ○ ○ Example 39 AL-45 PI-6 30 paa-4 70 ○ ○ ○ ○ Comparative Example 7 AL-46 paa-1 100 ○ × △ × Comparative Example 8 AL-47 paa-2 100 ○ ○ ○ × Comparative Example 9 AL-48 paa-3 100 △ × △ × Comparative Example 10 AL-49 paa-2 70 paa-7 30 ○ ○ ○ × Comparative Example 11 AL-50 pi-2 30 paa-4 70 ○ × △ ×

[0121] As shown in Table 4, Examples 29-39, which used liquid crystal alignment agents containing polymer [A] having partial structure (a), showed better results in terms of film strength (especially resistance to key press tests) compared to Comparative Examples 7-11, which used liquid crystal alignment agents without polymer [A]. Furthermore, Examples 29-39 also exhibited good liquid crystal alignment and adhesion to the substrate.

[0122] [Example 40: PSA type liquid crystal display element] 1. Preparation of liquid crystal alignment agents A solution containing 5 parts by mass of the polymer (PSQ-1) obtained in Synthesis Example 40 and a solution containing 95 parts by mass of the polymer (PI-7) obtained in Synthesis Example 34 were mixed and diluted with NMP and BC to prepare a solution with a solvent composition of NMP / BC = 50 / 50 (mass ratio) and a solid content concentration of 3.5% by mass. The solution was filtered using a filter with a pore size of 0.2 μm to prepare the liquid crystal alignment agent (AL-51).

[0123] 2. Preparation of liquid crystal compositions To obtain liquid crystal composition LC1, 5% by mass of a liquid crystal compound represented by formula (L1-1) and 0.3% by mass of a photopolymerizable compound represented by formula (L2-1) were added to 10 g of nematic liquid crystal (Merck, MLC-6608) and mixed. [Chemistry 24]

[0124] 3. Manufacturing of PSA-type liquid crystal display elements The prepared liquid crystal alignment agent (AL-51) was coated onto the transparent electrode surface of a glass substrate containing an ITO film and transparent electrodes using a rotator. After pre-baking on a hot plate at 80°C for 1 minute, the solvent was removed by heating at 200°C for 1 hour in a nitrogen-replaced oven, thereby forming a coating film (liquid crystal alignment film) with a thickness of 0.08 μm. The coating film was then rubbed using a rubbing machine with rollers wound with rayon cloth at a roller speed of 400 rpm, a stage movement speed of 3 cm / s, and a bristle indentation length of 0.1 mm. Then, it was ultrasonically cleaned in ultrapure water for 1 minute, followed by drying in a clean oven at 100°C for 10 minutes, thereby obtaining a substrate with a liquid crystal alignment film. The above operation was repeated to obtain a pair (two) substrates with liquid crystal alignment films. Furthermore, the rubbing treatment was a weak rubbing treatment performed for the purpose of controlling liquid crystal collapse and using a simple method for alignment separation. An epoxy resin adhesive containing 3.5 μm diameter alumina spheres is screen-printed onto the outer periphery of the surface of one substrate containing the liquid crystal alignment film. The liquid crystal alignment films of a pair of substrates are then overlapped and pressed together, and the adhesive is heat-cured at 150°C for 1 hour. Subsequently, the gap between the liquid crystal injection port and the substrate is filled with the liquid crystal composition LC1, and the liquid crystal injection port is sealed with an epoxy adhesive. To remove the flow alignment during liquid crystal injection, the mixture is heated at 150°C for 10 minutes and then slowly cooled to room temperature. Subsequently, an AC 10 V at a frequency of 60 Hz was applied between the electrodes of the obtained liquid crystal cell, and under liquid crystal driving conditions, ultraviolet light was applied using an ultraviolet irradiation device with a metal halide lamp as the light source, with an irradiation dose of 50,000 J / m². Furthermore, the irradiation dose was measured using a photometer with a wavelength of 365 nm as the reference. Thus, a PSA-type liquid crystal cell was manufactured.

[0125] 4. Evaluation For the liquid crystal cells manufactured in step 3, the liquid crystal alignment, adhesion, and film strength were evaluated using the same method as in Example 1. The evaluation results are shown in Table 5.

[0126] [Comparative Example 12] Except for changing the composition of the liquid crystal alignment agent as shown in Table 5, the liquid crystal alignment agent was prepared in the same manner as in Example 40. Furthermore, using the obtained liquid crystal alignment agent, PSA-type liquid crystal cells were manufactured in the same manner as in Example 40, and various evaluations were performed. The evaluation results are shown in Table 5. In Table 5, the values ​​in the mass ratio column represent the mixing ratio (parts by mass) of each compound (polymer, additive) based on solid components, relative to 100 parts by mass of the total polymer components used in the preparation of the liquid crystal alignment agent.

[0127] [Table 5] Orientation agent composition Characteristic evaluation as an alignment agent Polymer 1 Polymer 2 additive Orientation Tightness membrane strength abrasion resistance membrane strength Key resistance test type mass ratio type mass ratio type mass ratio Example 40 AL-51 PI-7 95 PSQ-1 5 ○ ○ ○ ○ Comparative Example 12 AL-52 pi-3 95 PSQ-1 5 ○ △ △ ×

[0128] As shown in Table 5, in Example 40, which used a liquid crystal alignment agent containing polymer [A], the liquid crystal alignment, adhesion, and film strength were all rated as good. In contrast, in Comparative Example 12, which used a liquid crystal alignment agent without polymer [A], the adhesion and film strength (abrasion resistance) were rated as "acceptable," while the film strength (button resistance test resistance) was rated as "poor."

[0129] [Example 41: Optical VA-type liquid crystal display element] 1. Preparation of liquid crystal alignment agents A solution containing 30 parts by mass of polymer (MI-1) obtained in Synthesis Example 41 and 70 parts by mass of polymer (PAA-2) obtained in Synthesis Example 2 was mixed and diluted with NMP and BC to prepare a solution with a solvent composition of NMP / BC = 80 / 20 (mass ratio) and a solid content concentration of 3.5% by mass. The solution was filtered using a filter with a pore size of 0.2 μm to prepare the liquid crystal alignment agent (AL-53).

[0130] 2. Manufacturing of VA-type liquid crystal display elements The prepared liquid crystal alignment agent (AL-53) was coated onto the transparent electrode surface of a glass substrate with a transparent electrode containing an ITO film using a spinner, and pre-baked on a hot plate at 80°C for 1 minute. Then, it was heated at 230°C for 1 hour in an oven with nitrogen-replaced material to form a coating with a thickness of 0.1 μm. Subsequently, the coating surface was irradiated with 1,000 J / m² of polarized ultraviolet light containing a bright line of 313 nm from a direction tilted 40° from the substrate normal using an Hg-Xe lamp and a Glan-Taylor prism to impart liquid crystal alignment capability. The same operation was repeated to prepare a pair (two) substrates with liquid crystal alignment films. An epoxy resin adhesive containing 3.5 μm diameter alumina spheres is applied via screen printing to the outer periphery of the surface of one substrate with a liquid crystal alignment film. The liquid crystal alignment films of the two substrates are then pressed together with their surfaces facing each other, ensuring the projection directions of the ultraviolet rays from each substrate onto the substrate surface are antiparallel. The adhesive is then thermosetting at 150°C for 1 hour. Next, a negative liquid crystal (Merck, MLC-6608) is filled into the gap between the substrates through the liquid crystal injection port, and the injection port is sealed with an epoxy adhesive. Finally, to remove the flow alignment during liquid crystal injection, the liquid crystal is heated to 130°C and then slowly cooled to room temperature.

[0131] 3. Evaluation For the liquid crystal cells manufactured in step 2, the liquid crystal alignment, adhesion, and film strength were evaluated using the same method as in Example 1. The evaluation results are shown in Table 6.

[0132] [Comparative Example 13] Except for changing the composition of the liquid crystal alignment agent as shown in Table 6, the liquid crystal alignment agent was prepared in the same manner as in Example 41. Furthermore, using the obtained liquid crystal alignment agent, optical VA-type liquid crystal cells were manufactured in the same manner as in Example 41, and various evaluations were performed. These results are shown in Table 6. In Table 6, the values ​​in the mass ratio column represent the mixing ratio (parts by mass) of each compound (polymer, additive) based on solid components relative to 100 parts by mass of the total polymer components used in the preparation of the liquid crystal alignment agent.

[0133] [Table 6] Orientation agent composition Characteristic evaluation as an alignment agent Polymer 1 Polymer 2 additive Orientation Tightness membrane strength abrasion resistance membrane strength Key resistance test type mass ratio type mass ratio type mass ratio Example 41 AL-53 PAA-2 70 MI-1 30 ○ ○ ○ ○ Comparative Example 13 AL-54 paa-1 70 MI-1 30 ○ ○ △ ×

[0134] As shown in Table 6, in Example 41, which used a liquid crystal alignment agent containing polymer [A], the liquid crystal alignment, adhesion, and film strength were all rated as good. In contrast, in Comparative Example 13, which used a liquid crystal alignment agent without polymer [A], the film strength (abrasion resistance) was rated as "acceptable," and the film strength (button resistance) was rated as "poor."

[0135] Based on the above results, it is clear that by using a liquid crystal alignment agent containing a polymer [A] having a partial structure (a), a liquid crystal element with excellent liquid crystal alignment can be obtained, and a liquid crystal alignment film with high adhesion and film strength can be formed.

Claims

1. A liquid crystal alignment agent comprising a polymer [A] having a partial structure (a) represented by formula (1) below, wherein the polymer [A] comprises structural units derived from a diamine having said partial structure (a), said diamine being a compound represented by formula (2) below, wherein, In each of the following formulas (2), the number of groups represented by "-CH2OR1" in the partial structure (a) represented by formula (1) is one or two. In formula (1), A1, A2, and A3 are each independently a divalent aromatic ring group; m is an integer from 0 to 2; wherein, when m is 0, at least one of the divalent aromatic ring groups represented by A1 and A3 has a structure formed by the group represented by "-CH2OR1" bonded to the aromatic ring; when m is 1 or 2, at least one of the divalent aromatic ring groups represented by A1, A2, and A3 has a structure formed by the group represented by "-CH2OR1" bonded to the aromatic ring; R1 is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a tert-butoxycarbonyl group, a 2-tetrahydropyranyl group, a methoxymethyl group, a 1-ethoxyethyl group, or an acetyl group; B1 and B2 are each independently -O-, -S-, -NR2-, -CO-, -CO -O-, -O-CO-, -CS-O-, -O-CS-, -NR2-CO-, -CO-NR2-, -NR2-CO-NR3- or an alkyldiyl group having 1 to 14 carbon atoms, or a divalent group formed by substituting any methylene group of an alkyldiyl group having 2 to 14 carbon atoms with at least one of -O-, -S-, -NR2-, -CO-, -CO-O-, -O-CO-, -CS-O-, -O-CS-, -NR2-CO-, -CO-NR2- and -NR2-CO-NR3-; R2 and R3 are independently hydrogen atoms or monovalent organic groups; when m is 2, the multiple A2s in the formula may be the same or different, and the multiple B2s may be the same or different; "*" indicates a bond. In formula (2), A1, A2, A3, B1 and B2 have the same meaning as in formula (1), m is 0 or 1, and D1 and D2 are independently single-bonded or divalent chain hydrocarbon groups, alicyclic hydrocarbon groups, aromatic hydrocarbon groups or nitrogen-containing heterocyclic groups.

2. The liquid crystal alignment agent as claimed in claim 1, wherein in the formula (1), B1 and B2, and the divalent aromatic ring group having a structure formed by the bonding of the group represented by "-CH2OR1" to the aromatic ring bonded by the group represented by "-CH2OR1", are bonded by -O-, -S-, -NR2-, -CO-, -CO-O-, -O-CO-, -CS-O-, -O-CS-, -NR2-CO-, -CO-NR2- or -NR2-CO-NR3- to the aromatic ring bonded by the group represented by "-CH2OR1".

3. The liquid crystal alignment agent as claimed in claim 1, wherein the polymer [A] is at least one selected from the group consisting of polyamide, polyamide ester and polyimide.

4. The liquid crystal alignment agent as claimed in claim 1 further comprises a polymer [Q] that does not have said partial structure (a).

5. The liquid crystal alignment agent as claimed in claim 4, wherein the polymer [Q] is at least one selected from the group consisting of polyamide, polyamide ester, polyimide, polyorganosiloxane and addition polymers.

6. A liquid crystal alignment film formed using a liquid crystal alignment agent as described in any one of claims 1 to 5.

7. A liquid crystal element comprising a liquid crystal alignment film as described in claim 6.

8. A polymer, being a polyamide, polyamide ester, or polyimide, comprising structural units derived from a diamine having a partial structure represented by formula (1), wherein the diamine is a compound represented by formula (2), wherein, In each of the following formulas (2), the number of groups represented by "-CH2OR1" in the partial structure (a) represented by formula (1) is one or two. In formula (1), A1, A2, and A3 are each independently a divalent aromatic ring group; m is an integer from 0 to 2; wherein, when m is 0, at least one of the divalent aromatic ring groups represented by A1 and A3 has a structure formed by the group represented by "-CH2OR1" bonded to the aromatic ring; when m is 1 or 2, at least one of the divalent aromatic ring groups represented by A1, A2, and A3 has a structure formed by the group represented by "-CH2OR1" bonded to the aromatic ring; R1 is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a tert-butoxycarbonyl group, a 2-tetrahydropyranyl group, a methoxymethyl group, a 1-ethoxyethyl group, or an acetyl group; B1 and B2 are each independently -O-, -S-, -NR2-, -CO-, -CO -O-, -O-CO-, -CS-O-, -O-CS-, -NR2-CO-, -CO-NR2-, -NR2-CO-NR3- or an alkyldiyl group having 1 to 14 carbon atoms, or a divalent group formed by substituting any methylene group of an alkyldiyl group having 2 to 14 carbon atoms with at least one of -O-, -S-, -NR2-, -CO-, -CO-O-, -O-CO-, -CS-O-, -O-CS-, -NR2-CO-, -CO-NR2- and -NR2-CO-NR3-; R2 and R3 are independently hydrogen atoms or monovalent organic groups; when m is 2, the multiple A2s in the formula may be the same or different, and the multiple B2s may be the same or different; "*" indicates a bond. In formula (2), A1, A2, A3, B1 and B2 have the same meaning as in formula (1), m is 0 or 1, and D1 and D2 are independently single-bonded or divalent chain hydrocarbon groups, alicyclic hydrocarbon groups, aromatic hydrocarbon groups or nitrogen-containing heterocyclic groups.