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

Abstract

To provide a liquid crystal alignment agent that has good liquid crystal alignment properties, has good DC storage characteristics and DC relaxation characteristics, and reduces the generation of an afterimage.SOLUTION: A liquid crystal alignment agent contains a polymer (P). The polymer (P) includes one or more of a partial structure (U2-1), a partial structure (U2-2), and a partial structure (U2-3), and a partial structure (U1) in the same molecule, and the molecule including the partial structure (U1) includes two or more of the partial structure (U2-1), partial structure (U2-2), and partial structure (U2-3) in the same molecule or in different molecules. The partial structure (U1) has a partial structure obtained by removing two hydrogen atoms from a structure represented by the formula (Y-1). The partial structure (U2-1) includes, in a main chain, a partial structure in which a chain-like hydrocarbon structure and *1-NR1-CO- and the like are adjacent to each other. The partial structure (U2-2) has a carboxylic acid group or a sulfonic acid group. The partial structure (U2-3) has nitrogen-containing heterocycles.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal element. [Background technology]

[0002] Liquid crystal elements are used in a wide range of applications, from relatively large display devices such as LCD televisions and information displays to small display devices such as smartphones. The performance of a liquid crystal element is determined by various characteristics such as the orientation of the liquid crystals, the size of the pre-tilt angle, and the voltage retention rate. In order to improve the performance of liquid crystal elements, improvements have been made to the liquid crystal alignment film, which aligns the liquid crystals in a specific direction.

[0003] When voltage is applied to a liquid crystal element, charge accumulates within the liquid crystal cell, which can be perceived by the observer as an afterimage (DC afterimage), potentially degrading the display quality of the liquid crystal element. Therefore, one of the required characteristics of a liquid crystal alignment film is low charge accumulation.

[0004] Therefore, various techniques have been proposed to suppress the accumulation of charge within liquid crystal cells and improve the display quality of liquid crystal elements (see, for example, Patent Document 1 and Patent Document 2). Patent Document 1 discloses reducing accumulated charge by incorporating a polyamic acid obtained by reacting a diamine compound containing a nitrogen-containing diamine such as N4,N4'-bis(4-aminophenyl)-benzidine with a tetracarboxylic dianhydride into a liquid crystal alignment agent. Patent Document 2 discloses obtaining a liquid crystal alignment film with rapid relaxation of accumulated charge by incorporating a polymer obtained from a diamine having a structure in which a carbazole structure and a benzene ring are bonded by an amino group into a liquid crystal alignment agent. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2008-107811 [Patent Document 2] International Publication No. 2018 / 110354 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] With the increasing demand for higher quality liquid crystal elements, there is a need to develop liquid crystal elements that produce even less afterimages. To suppress afterimages and improve the quality of liquid crystal elements, it is necessary that charge does not easily accumulate in the liquid crystal cell even when a voltage is applied (hereinafter also referred to as "DC accumulation characteristics"), and that any accumulated charge is quickly relieved (hereinafter also referred to as "DC relaxation characteristics"). Furthermore, in order to obtain high-quality liquid crystal elements, it is desirable that both DC accumulation characteristics and DC relaxation characteristics are good while maintaining good liquid crystal alignment, which is one of the basic characteristics of liquid crystal elements.

[0007] The present invention has been made in view of the above problems, and one objective is to provide a liquid crystal alignment agent that can produce a liquid crystal element having good liquid crystal alignment properties, good DC accumulation characteristics and DC relaxation characteristics, and less afterimage. [Means for solving the problem]

[0008] According to the present invention, the following means are provided.

[0009] <1> A liquid crystal alignment agent comprising a polymer (P), wherein the polymer (P) contains within the same molecule a substructure represented by formula (1) below and one or more substructures represented by formula (2), formula (3), and formula (4), and a molecule containing the substructure represented by formula (1) below contains two or more substructures represented by formula (2), formula (3), and formula (4) below within the same molecule or in different molecules. [ka] (In formula (1), X 1 Y is a tetravalent organic group. 1is a divalent organic group having a partial structure formed by removing two hydrogen atoms from the structure represented by the following formula (Y-1). )

Chemical Formula

Chemical Formula

[0010] <2> The polymer (P) contains within the same molecule any two or more of the substructures represented by formula (1), formula (2), formula (3), and formula (4). <1> The liquid crystal alignment agent described above. <3> The polymer (P) contains structural units derived from aromatic tetracarboxylic dianhydride, <1> or <2> The liquid crystal alignment agent described above. <4> The above further contains a polymer (Q) different from the polymer (P). <1> ~ <3> A liquid crystal alignment agent as described in any of the following. <5> The polymer (Q) contains a polymer that includes at least one selected from the group consisting of a substructure represented by the following formula (5) and a substructure represented by the following formula (6). <4> The liquid crystal alignment agent described above. [ka] (In equations (5) and (6), X5 and X 6 These are, independently, tetravalent groups having an alicyclic structure. 5 and Y 6 These are divalent organic groups, each independently containing a substructure in which a thermally leaveable group is bonded to a nitrogen atom.

[0011] <6> The alicyclic structure is a substituted or unsubstituted cyclobutane ring structure. <5> The liquid crystal alignment agent described above. <7> The above further contains a compound having three or more of at least one group selected from the group consisting of an oxyranyl group, an oxetanyl group, a hydroxyl group, a mercapto group, an amino group, and a polymerizable carbon-carbon double bond group in one molecule. <1> ~ <6> A liquid crystal alignment agent as described in any of the following. <8> The above further contains a compound having a trialkoxysilyl group. <1> ~ <7> A liquid crystal alignment agent as described in any of the following. <9> the above <1> ~ <8> A liquid crystal alignment film formed using any of the liquid crystal alignment agents described in one of the following. <10> the above <9> A liquid crystal element comprising the liquid crystal alignment film described above. [Effects of the Invention]

[0012] According to the liquid crystal alignment agent of the present invention, it is possible to obtain a liquid crystal element that maintains good liquid crystal alignment, has good DC storage characteristics and DC relaxation characteristics, and is less prone to afterimages caused by charge accumulation. [Modes for carrying out the invention]

[0013] Liquid crystal alignment agent The components included in the liquid crystal alignment agent of this disclosure, as well as other components that may be optionally added as needed, are described below. Unless otherwise specified, each component may be used alone or in combination of two or more.

[0014] Herein, in this specification, "hydrocarbon group" means a group of hydrocarbons including linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. "Linear hydrocarbon group" means a linear hydrocarbon group or a branched hydrocarbon group that does not contain a cyclic structure in its main chain and consists only of a linear structure. However, linear hydrocarbon groups may be saturated or unsaturated. "Alicyclic hydrocarbon group" means a hydrocarbon group that contains only the structure of an alicyclic hydrocarbon as its ring structure and does not contain an aromatic ring structure. However, an alicyclic hydrocarbon group does not have to consist only of the structure of an alicyclic hydrocarbon, and may also include a linear structure as part of it. "Aromatic hydrocarbon group" means a hydrocarbon group that contains an aromatic ring structure as its ring structure. However, an aromatic hydrocarbon group does not have to consist only of an aromatic ring structure, and may include a linear structure or an alicyclic hydrocarbon structure as part of it. "Aromatic ring" means an aromatic hydrocarbon ring and an aromatic heterocycle. "Organic group" means an atomic group obtained by removing any hydrogen atom from a carbon-containing compound (i.e., an organic compound).

[0015] The "main chain" of a polymer refers to the "trunk" portion of the polymer, which consists of the longest chain of atoms. This "trunk" portion may contain a ring structure. For example, "having a specific structure in the main chain" means that the specific structure constitutes a part of the main chain. "Side chains" refer to the parts of a polymer that branch off from the "trunk." "Tetracarboxylic acid derivatives" include tetracarboxylic dianhydrides, tetracarboxylic diesters, and tetracarboxylic diester dihalides.

[0016] The liquid crystal alignment agent of this disclosure contains a polymer (P). Polymer (P) is at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide, and is an aggregate of polymers containing a substructure (U1) within the molecule. Furthermore, the molecules constituting polymer (P) contain one or more of substructures (U2-1), (U2-2), and (U2-3) and substructure (U1) within the same molecule, and the molecules containing substructure (U1) contain two or more of substructures (U2-1), (U2-2), and (U2-3) within the same molecule or different molecules. For each substructure, substructure (U1) has a specific nitrogen-containing structure that imparts hole transportability to the polymer. Substructure (U2-1) has a structure that imparts hydrogen bonding ability to the main chain of the polymer. Substructure (U2-2) has an acidic functional group, and substructure (U2-3) has a nitrogen-containing heterocycle.

[0017] Here, a molecule containing substructure (U1) is said to contain "two or more of substructures (U2-1), (U2-2), and (U2-3)" within the same molecule or in different molecules, which means that the polymer (P), which is an aggregate of polymers, contains two of the three substructures (U2-1), (U2-2), and (U2-3), or all three. Specifically, if polymer (P) contains any two of the three substructures (U2-1), (U2-2), and (U2-3), polymer (P) (i.e., the aggregate of polymers containing substructure (U1)) contains substructure (U2-1) and substructure (U2-2), substructure (U2-1) and substructure (U2-3), or substructure (U2-2) and substructure (U2-2) within the same molecule or different molecules. Furthermore, if polymer (P) contains all three substructures (U2-1), (U2-2), and (U2-3), polymer (P) contains substructure (U2-1), substructure (U2-2), and substructure (U2-3) within the same molecule or different molecules. Specific embodiments of polymer (P) are as follows: <1> ~ <4> These are some examples.

[0018] <1> A molecule containing substructure (U1) contains substructure (U2-1) and substructure (U2-2) within the same molecule or within different molecules. <2> A molecule containing substructure (U1) contains substructure (U2-1) and substructure (U2-3) within the same molecule or within different molecules. <3> A molecule containing substructure (U1) contains substructures (U2-2) and (U2-3) within the same molecule or in different molecules. <4> A polymer in which a molecule containing substructure (U1) contains substructures (U2-1), (U2-2), and (U2-3) within the same molecule or in different molecules.

[0019] Furthermore, the above <1> ~ <4> Each polymer may contain only one substructure (U1) or two or more substructures. <1> , <2> and <4> Each polymer may contain only one substructure (U2-1) or two or more substructures. <1> , <3> and <4> Each polymer may contain only one substructure (U2-2) or two or more substructures. <2> ~ <4> Each polymer may contain only one substructure (U2-3) or two or more substructures.

[0020] A specific example of a polymer (P) containing two or more of the substructures (U2-1), (U2-2), and (U2-3) within different molecules is, for example, the above. <1> In this case, an embodiment is given in which the polymer (P) includes a polymer having substructure (U1) and substructure (U2-1) within the same molecule, and a polymer having substructure (U1) and substructure (U2-2) within the same molecule. <4> Examples of such embodiments include: a polymer (P) having substructures (U1) and (U2-1) within the same molecule, a polymer having substructures (U1) and (U2-2) within the same molecule, and a polymer having substructures (U1) and (U2-3) within the same molecule; a polymer having substructures (U1), (U2-1), and (U2-2) within the same molecule, and a polymer having substructures (U1) and (U2-3) within the same molecule; a polymer having substructures (U1) and (U2-1) within the same molecule, and a polymer having substructures (U1), (U2-2), and (U2-3) within the same molecule; and so on.

[0021] In order to obtain a liquid crystal element with good DC storage characteristics and DC relaxation characteristics, thereby reducing afterimages, while minimizing the number of components constituting the liquid crystal alignment agent, it is preferable that the polymer (P) contains two or more of the substructures (U2-1), (U2-2), and (U2-3), and substructure (U1) within the same molecule.

[0022] The details of substructure (U1), substructure (U2-1), substructure (U2-2), and substructure (U2-3) are described below.

[0023] <Substructure (U1)> A substructure (U1) is a structural unit represented by the following formula (1). [ka] (In formula (1), X 1 Y is a tetravalent organic group. 1This is a divalent organic group having a substructure obtained by removing two hydrogen atoms from the structure represented by the following formula (Y-1). [ka] (In formula (Y-1), A 1 and A 2 Each of these is independently a monovalent group having an aromatic hydrocarbon ring, where the aromatic hydrocarbon ring is bonded to the nitrogen atom in formula (Y-1), or A 1 and A 2 When these are combined with each other, A 1 and A 2 This represents a nitrogen-containing condensed heterocyclic structure formed together with the nitrogen atom to which it is bonded. 3 is a hydrogen atom or a monovalent organic group. However, A 1 and A 2 However, when combined with each other, A 1 and A 2 When representing a nitrogen-containing condensed heterocyclic structure composed of a nitrogen atom to which it is bonded, the nitrogen-containing condensed heterocyclic structure has two or more aromatic hydrocarbon rings, and the two aromatic hydrocarbon rings of the nitrogen-containing condensed heterocyclic structure have a condensed ring structure in which the nitrogen atom in formula (Y-1) is shared and bonded, or A 3 It has an aromatic hydrocarbon ring, A 3 The aromatic hydrocarbon ring present in the compound is bonded to the nitrogen atom in formula (Y-1).

[0024] In the above equation (1), Y 1 A is a group derived from a diamine (hereinafter also referred to as "specific diamine (D1)") having a substructure obtained by removing two hydrogen atoms from the structure represented by the above formula (Y-1). 1 and A 2 However, each has an aromatic hydrocarbon ring, A 1 and A 2 If the aromatic hydrocarbon ring possessed by is bonded to the nitrogen atom in formula (Y-1) by a single bond, then A 1 and A 2 The aromatic hydrocarbon ring inside may be monocyclic or polycyclic. 1 and A 2Examples of aromatic hydrocarbon rings within include benzene rings, naphthalene rings, and anthracene rings. Of these, A 1 and A 2 The aromatic hydrocarbon ring inside is preferably a benzene ring or a naphthalene ring, and more preferably a benzene ring. 1 and A 2 The aromatic hydrocarbon ring inside may have substituents. Examples of such substituents include methyl groups, ethyl groups, halogen atoms, and the like.

[0025] A 1 and A 2 However, when combined with each other, A 1 and A 2 When referring to a nitrogen-containing condensed heterocyclic structure formed together with a bonded nitrogen atom, examples of such nitrogen-containing condensed heterocyclic structures include indoline structures, indole structures, 1,2,3,4-tetrahydroquinoline structures, 1,2-dihydroquinoline structures, 1,2-dihydroisoquinoline structures, carbazole structures, phenoxazine structures, phenothiazine structures, and the like. These heterocyclic structures may have substituents in the ring portion. Examples of such substituents include methyl groups, ethyl groups, halogen atoms, and the like. 1 and A 2 Among these, the nitrogen-containing condensed heterocyclic structures formed by combining these elements are preferably indoline, indole, 1,2,3,4-tetrahydroquinoline, 1,2-dihydroquinoline, 1,2-dihydroisoquinoline, and carbazole structures.

[0026] A 3 When the group is a monovalent organic group, examples of such monovalent organic groups include monovalent hydrocarbon groups having 1 to 10 carbon atoms and thermally desorbed groups. Examples of monovalent hydrocarbon groups include alkyl groups having 1 to 10 carbon atoms, cycloalkyl groups having 3 to 10 carbon atoms, and aryl groups having 6 to 10 carbon atoms.

[0027] A thermally leaving group is a substituent that is eliminated by heat applied to a liquid crystal alignment agent during the formation of a liquid crystal alignment film or the like and is replaced with a hydrogen atom. Examples of thermally leaving groups include carbamate-based protecting groups, amide-based protecting groups, imide-based protecting groups, sulfonamide-based protecting groups, and the like. Among these, carbamate-based protecting groups are preferred because of their high thermal elimination properties. Specific examples thereof include a tert-butoxycarbonyl group, a benzyloxycarbonyl group, a 1,1-dimethyl-2-haloethyloxycarbonyl group, an allyloxycarbonyl group, a 2-(trimethylsilyl)ethoxycarbonyl group, a 9-fluorenylmethyloxycarbonyl group, an allyloxycarbonyl group, and the like. Among these, a tert-butoxycarbonyl group (Boc group) is particularly preferred because it has excellent thermal elimination properties and can reduce the residual amount of the deprotected portion in the film.

[0028] A 1 and A 2 represent the above nitrogen-containing fused heterocyclic structure, the nitrogen-containing fused heterocyclic structure represented by A 1 and A 2 has two or more aromatic hydrocarbon rings, and the two aromatic hydrocarbon rings of the nitrogen-containing fused heterocyclic structure have a fused ring structure in which the nitrogen atom in formula (Y-1) is shared and bonded (hereinafter also referred to as "fused ring structure Cp"), or A 3 has an aromatic hydrocarbon ring, and the aromatic hydrocarbon ring is bonded to the nitrogen atom in formula (Y-1). Examples of the fused ring structure Cp include a carbazole structure, a phenoxazine structure, a phenothiazine structure, and the like, with a carbazole structure being preferred.

[0029] Y in the above formula (1) 1 only needs to have a partial structure formed by removing two hydrogen atoms from the structure represented by the above formula (Y-1). The hydrogen atoms removed from the structure represented by the above formula (Y-1) are selected from A 1 , A 2 and A 3 may be a hydrogen atom possessed by any of them. Specifically, Y in the above formula (1) 1 is A 1 and A 2It may be a divalent group having a substructure in which one hydrogen atom is removed from each of the two, or A 1 and A 3 It may also be a divalent group having a substructure in which one hydrogen atom is removed from each of the two components.

[0030] Y 1 From the viewpoint of sufficiently reducing afterimages generated in liquid crystal elements, it is preferable that the main chain has a substructure derived from the above formula (Y-1). 1 The number of substructures derived from the above formula (Y-1) may be one or two or more.

[0031] Y 1 A specific example of a divalent organic group represented by the formula shown below is the group represented by the formula shown below. [ka] (In the formula, "*" represents a combination.)

[0032] In polymer (P), the content of structural units derived from the specific diamine (D1) is preferably 3 mol% or more, and more preferably 5 mol% or more, relative to the total amount of diamine-derived structural units in polymer (P). Furthermore, the content of structural units derived from the specific diamine (D1) is preferably 90 mol% or less, and more preferably 80 mol% or less, relative to the total amount of diamine-derived structural units in polymer (P). By setting the content of structural units derived from the specific diamine (D1) within the above range, the DC afterimage characteristics (especially DC relaxation characteristics) of the liquid crystal element can be improved, and the occurrence of DC afterimages can be sufficiently reduced.

[0033] Furthermore, if the polymer (P) contains two or more polymers with different monomer compositions, the proportion of structural units derived from the specific diamine (D1) refers to the proportion of structural units derived from the diamine constituting the polymer (P) to the total amount of structural units derived from the diamine constituting the polymer (P). For example, if the liquid crystal alignment agent of this disclosure contains a first polymer and a second polymer having different monomer compositions as the polymer (P), the proportion of structural units derived from the specific diamine (D1) represents the ratio of the total amount of structural units derived from the specific diamine (D1) constituting the first polymer and the total amount of structural units derived from the diamine constituting the second polymer to the total amount of structural units derived from the specific diamine (D1) constituting the first polymer and the total amount of structural units derived from the diamine constituting the second polymer (the same applies to the following structural units).

[0034] <Substructure (U2-1)> A substructure (U2-1) is a structural unit represented by the following formula (2). [ka] (In formula (2), X 2 Y is a tetravalent organic group. 2 The chain-like hydrocarbon structure and "* 1 -NR 1 -CO-", * 1 -CO-NR 1 -", * 1 -NR 1 -CO-NR 2 -" or "* 1 -CO-NR 1 -NR 2 It is a divalent group that contains a substructure adjacent to "-CO-" in the main chain. 1 and R 2 Each of these is independently a hydrogen atom or a monovalent organic group. 1 (This symbol represents a bond with a chain-like hydrocarbon structure.)

[0035] In the above equation (2), Y 2 The chain-like hydrocarbon structure and "* 1 -NR 1 -CO-", * 1 -CO-NR 1 -", * 1-NR 1 -CO-NR 2 -" or "* 1 -CO-NR 1 -NR 2 This group is derived from a diamine (hereinafter also called "specific diamine (D2-1)") that contains a substructure adjacent to "-CO-" in its main chain. 2 The chain-like hydrocarbon structure of Y may be saturated or unsaturated. 2 The chain-like hydrocarbon structure possessed by may be linear or branched, but is preferably a linear saturated or unsaturated hydrocarbon group, specifically a linear alkanediyl group and an alkenediyl group. 1 -NR 1 -CO-", * 1 -CO-NR 1 -", -NR 1 -CO-NR 2 -" or "-CO-NR" 1 -NR 2 The number of carbon atoms per chain-like hydrocarbon structure adjacent to "-CO-" is preferably 1 to 10, more preferably 2 to 8, and even more preferably 2 to 5.

[0036] Note Y 2 The chain-like hydrocarbon structure and "* 1 -NR 1 -CO-", * 1 -CO-NR 1 -", * 1 -NR 1 -CO-NR 2 -" or "* 1 -CO-NR 1 -NR 2 As long as the main chain has adjacent substructures of "-CO-", it may further have a cyclic structure. 2 The annular structure that Y may have is not particularly limited. 2 Specific examples of cyclic structures that may be present include alicyclic groups such as cycloalkanediyl groups and cycloalkenediyl groups; aromatic hydrocarbon groups such as phenylene groups; and heterocyclic groups such as piperidinediyl groups, piperazinediyl groups, pyridinediyl groups, and pyridazinediyl groups.

[0037] * 1 -NR 1 -CO-", * 1 -CO-NR 1 -", * 1 -NR 1 -CO-NR 2 -" or "* 1 -CO-NR 1 -NR 2 In the group represented as "-CO-", R 1 and R 2 If it is a monovalent organic group, R 1 and R 2 Specific examples include monovalent hydrocarbon groups having 1 to 10 carbon atoms and thermally desorbable groups. 1 and R 2 If is a monovalent hydrocarbon group, the monovalent hydrocarbon group is preferably an alkyl group having 1 to 3 carbon atoms or a phenyl group, and more preferably an alkyl group having 1 to 3 carbon atoms. A specific example of a thermally detachable group is A in formula (1) above. 3 In the explanation of A 3 Examples of groups that are thermally detachable include those similar to the group exemplified above. Among these, the tert-butoxycarbonyl group (Boc group) is particularly preferred because it exhibits excellent thermal detachment properties and can reduce the amount of residue remaining in the film of the deprotected portion.

[0038] R 1 and R 2 Of the above, a hydrogen atom, a C1-C3 alkyl group, or a thermally desorbable group is preferred, a hydrogen atom, a C1-C3 alkyl group, or a tert-butoxycarbonyl group is more preferred, and a hydrogen atom is even more preferred.

[0039] * 1 -NR 1 -CO-", * 1 -CO-NR 1 -", * 1 -NR 1 -CO-NR 2 -" or "* 1 -CO-NR 1 -NR 2 -CO-" and "* 1 A chain-like hydrocarbon structure is bonded to the "side."1 On the opposite side of ", a chain-like hydrocarbon structure may be adjacent, or a structure different from the chain-like hydrocarbon structure (specifically, a cyclic hydrocarbon group or a heterocyclic group) may be adjacent. Also, "* 1 The group adjacent to the opposite side may have substituents such as halogen atoms or hydroxyl groups.

[0040] Y 2 A preferred example of this is a divalent group represented by the following formula (y²-1). *-Ar 1 -R 3 -Z 1 -(R 4 -Z 2 ) n -R 5 -Ar 2 -* …(y2-1) (In formula (y2-1), Ar 1 and Ar 2 These are each independently divalent aromatic ring groups or alicyclic groups. 1 and Z 2 Each of them is independent of "* 1 -NR 1 -CO-", * 1 -CO-NR 1 -", * 1 -NR 1 -CO-NR 2 -" or "* 1 -CO-NR 1 -NR 2 -CO-" is "* 1 " represents a bond with a chain-like hydrocarbon structure. 3 and R 5 Each of these is independently a single-bonded or divalent chain-like hydrocarbon group. 4 R is a divalent organic group. 3 If it is a single bond, Z 1 R that joins 4 R is a divalent chain-like hydrocarbon group. 5 If it is a single bond, Ar 2 Adjacent to Z 2 R that joins 4 is a divalent chain hydrocarbon group. n is an integer between 0 and 2. "*" represents a bond.

[0041] In the above equation (y2-1), Ar 1 Or Ar 2 The divalent aromatic ring group represented by is a group obtained by removing two hydrogen atoms from the ring portion of an aromatic ring. Examples of such aromatic rings include benzene rings, naphthalene rings, pyridine rings, and pyrimidine rings. 1 Or Ar 2 The divalent alicyclic group represented by is a group obtained by removing two hydrogen atoms from the ring portion of an aliphatic ring such as a cyclohexane ring. 1 Or Ar 2 The divalent aromatic ring group or alicyclic group represented by may have substituents on the ring portion. Examples of such substituents include a methylene group, an ethylene group, a halogen atom, etc. 1 and Ar 2 From the viewpoint of forming a liquid crystal alignment film that exhibits good liquid crystal alignment properties, a phenylene group is preferred among these.

[0042] R 3 and R 5 If R is a divalent chain hydrocarbon group, 3 and R 5 Examples include linear alkanediyl groups and alkenediyl groups. 3 and R 5 The divalent chain hydrocarbon group represented is preferably a linear alkanediyl group, and more preferably a linear alkanediyl group having 1 to 5 carbon atoms.

[0043] R 4 Examples of divalent organic groups represented by include divalent hydrocarbon groups and heterocyclic groups. Examples of divalent hydrocarbon groups include chain hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. 4 Specific examples of divalent organic groups represented by include alkanediyl groups, alkenediyl groups, cycloalkanediyl groups, cycloalkenediyl groups, phenylene groups, piperidinediyl groups, piperazinediyl groups, pyridinediyl groups, and pyridazinediyl groups.

[0044] Y2 A specific example of a divalent organic group represented by the formula shown below is the group represented by the formula shown below. [ka] [ka] [ka] (In the formula, "Boc" represents a tert-butoxycarbonyl group. "*" represents a bond.)

[0045] When the polymer (P) contains structural units derived from a specific diamine (D2-1), the content of these units is preferably 5 mol% or more, and more preferably 10 mol% or more, relative to the total amount of diamine-derived structural units in the polymer (P). Furthermore, the content of structural units derived from the specific diamine (D2-1) is preferably 90 mol% or less, and more preferably 80 mol% or less, relative to the total amount of diamine-derived structural units in the polymer (P). By setting the content of structural units derived from the specific diamine (D2-1) within the above range, the DC afterimage characteristics (especially DC accumulation characteristics) of the liquid crystal element can be improved, and the generation of DC afterimages can be sufficiently reduced.

[0046] <Substructure (U2-2)> A substructure (U2-2) is a structural unit represented by the following formula (3). [ka] (In formula (3), X 3 Y is a tetravalent organic group. 3 (This refers to a divalent organic group having a carboxylic acid group or a sulfonic acid group.)

[0047] In the above equation (3), Y 3 This group is derived from a diamine having a carboxylic acid group or a sulfonic acid group (hereinafter also referred to as "specific diamine (D2-2)"). 3The carboxylic acid group or sulfonic acid group inside may be bonded to the chain structure or to the ring structure. 3 Preferably, the carboxylic acid group or sulfonic acid group is bonded to the aromatic ring structure directly or via a divalent linking group, and more preferably directly to the aromatic ring structure. When the carboxylic acid group or sulfonic acid group is bonded to the aromatic ring structure via a divalent linking group, the divalent linking group may be, for example, any methylene group in an alkanediyl group having 1 to 3 carbon atoms or an alkanediyl group having 2 to 4 carbon atoms, which is -O-, -CO-, -COO-, -NR 6 - or -CO-NR 6 - is replaced by a divalent group (R 6 Examples include hydrogen atoms or monovalent organic groups. 3 The number of carboxylic acid groups or sulfonic acid groups present is not particularly limited, and is, for example, 1 to 4, preferably 1 or 2.

[0048] Y 3 A specific example of a divalent group represented by the formula shown below is the group represented by the formula shown below. [ka] (In the formula, "*" represents a combination.)

[0049] When the polymer (P) contains structural units derived from a specific diamine (D2-2), the content of these units is preferably 5 mol% or more, and more preferably 10 mol% or more, relative to the total amount of diamine-derived structural units in the polymer (P). Furthermore, the content of structural units derived from the specific diamine (D2-2) is preferably 90 mol% or less, and more preferably 60 mol% or less, relative to the total amount of diamine-derived structural units in the polymer (P). By setting the content of structural units derived from the specific diamine (D2-2) within the above range, the DC afterimage characteristics (especially DC accumulation characteristics) of the liquid crystal element can be improved, and the generation of DC afterimages can be sufficiently reduced.

[0050] <Substructure (U2-3)> A substructure (U2-3) is a structural unit represented by the following formula (4). [ka] (In formula (4), X 4 Y is a tetravalent organic group. 4 This is a nitrogen-containing heterocycle, "-R 3 -NR 4 -R 5 -" and "-R 6 -NR 7 R 8 A divalent organic group having at least one substructure selected from the group consisting of (where Y 2 (Excluding the group corresponding to R.) 3 , R 5 and R 6 These are each independently divalent aliphatic hydrocarbon groups. 4 , R 7 and R 8 Each of these is independently a hydrogen atom, a thermally leaving group, or a monovalent aliphatic hydrocarbon group.

[0051] In the above equation (4), Y 4 This is a nitrogen-containing heterocycle, "-R 3 -NR 4 -R 5 -" and "-R 6 -NR 7 R 8 It is a group derived from a diamine (hereinafter also called "specific diamine (D2-3)") having at least one substructure (hereinafter also called "nitrogen-containing structure Ny") selected from the group consisting of the following: 4 If Y has a nitrogen-containing heterocycle, that nitrogen-containing heterocycle may be an aromatic heterocycle or a non-aromatic heterocycle. 4 The nitrogen-containing heterocycle inside may be a monocycle or a fused ring. 4Specific examples of nitrogen-containing heterocycles include nitrogen-containing aromatic heterocycles such as pyrrole rings, imidazole rings, pyrazole rings, triazole rings, pyridine rings, pyrimidine rings, pyridazine rings, quinoline rings, benzimidazole rings, carbazole rings, and pyrazine rings, as well as heterocycles having substituents (e.g., methyl groups, ethyl groups, etc.) on these rings. Examples of nitrogen-containing non-aromatic heterocycles include piperidine rings, piperazine rings, morpholine rings, and hexamethyleneimine rings, as well as heterocycles in which substituents (e.g., methyl groups, ethyl groups, etc.) have been introduced on these rings. Among these, Y 4 The nitrogen-containing heterocycle in the compound preferably has a structure in which at least one selected from the group consisting of a pyridine ring, pyrimidine ring, pyrazine ring, piperidine ring, piperazine ring, quinoline ring, benzimidazole ring, and carbazole ring is present.

[0052] R 3 , R 5 or R 6 Examples of divalent aliphatic hydrocarbon groups represented by include alkanediyl groups, alkenediyl groups, and cycloalkanediyl groups. 3 , R 5 or R 6 Of these, the divalent aliphatic hydrocarbon group represented is preferably an alkanediyl group. R 4 , R 7 or R 8 The monovalent aliphatic hydrocarbon group represented is preferably an alkyl group, and more preferably an alkyl group having 1 to 3 carbon atoms. R 4 , R 7 or R 8 A specific example of a thermally detachable group represented by the above formula (1) is A 3 In the explanation of A 3 Examples of groups that are thermally leaving groups include those similar to the group exemplified above. Among these, the tert-butoxycarbonyl group (Boc group) is particularly preferred.

[0053] Y 4The nitrogen-containing structure Ny may be present in the main chain of the polymer, in the side chain, or in both the main chain and the side chain. From the viewpoint of obtaining a liquid crystal element with sufficiently reduced afterimage, Y 4 It is preferable that the polymer has a nitrogen-containing structure Ny in its side chains. 4 The number of nitrogen-containing structures Ny present is not particularly limited, and can be, for example, 1 to 4, preferably 1 to 3.

[0054] Y 4 The group may consist solely of nitrogen-containing heterocycles, or it may have a ring structure or chain structure different from the nitrogen-containing heterocycle. Furthermore, these ring and chain structures may be in the main chain or side chains of the polymer. The chain structure may consist of an alkanediyl group having 1 to 10 carbon atoms, and any methylene group in the alkanediyl group being -O-, -CO-, -COO-, or -NR. 7 - or -CO-NR 7 - is replaced by a divalent group (R 7 Examples include hydrogen atoms or monovalent organic groups. Examples of ring structures different from nitrogen-containing heterocycles include aromatic hydrocarbon rings (benzene rings, naphthalene rings, etc.).

[0055] However, Y 4 This is the Y that the above equation (2) has 2 It is a different group. In other words, specific diamine (D2-3) is a different compound from specific diamine (D2-1), and Y 4 The chain-like hydrocarbon structure and "* 1 -NR 1 -CO-", * 1 -CO-NR 1 -", * 1 -NR 1 -CO-NR 2 -" or "* 1 -CO-NR 1 -NR 2 It is a divalent group that does not have a substructure adjacent to "-CO-" in the main chain. Note that the specific diamines (D1), (D2-1), (D2-2), and (D2-3) that constitute polymer (P) are all different compounds.

[0056] Y 4 A specific example of a divalent organic group represented by the formula is a group having a nitrogen-containing structure Ny in its main chain, represented by the following formula. [ka] (In the formula, "*" represents a combination.)

[0057] Also, Y 4 A specific example of a divalent organic group represented by the formula is a group having a nitrogen-containing structure Ny in its side chain, represented by the following formula. [ka] (In the formula, "*" represents a combination.)

[0058] When the polymer (P) contains structural units derived from a specific diamine (D2-3), the content of these units is preferably 3 mol% or more, and more preferably 5 mol% or more, relative to the total amount of diamine-derived structural units in the polymer (P). Furthermore, the content of structural units derived from the specific diamine (D2-3) is preferably 90 mol% or less, and more preferably 60 mol% or less, relative to the total amount of diamine-derived structural units in the polymer (P). By setting the content of structural units derived from the specific diamine (D2-3) within the above range, the DC afterimage characteristics (especially DC accumulation characteristics) of the liquid crystal element can be improved, and the generation of DC afterimages can be sufficiently reduced.

[0059] In polymer (P), the total content of structural units derived from specific diamine (D2-1), specific diamine (D2-2), and specific diamine (D2-3) is preferably 10 mol% or more, and more preferably 20 mol% or more, relative to the total amount of diamine-derived structural units in polymer (P). Furthermore, the total content of structural units derived from specific diamine (D2-1), specific diamine (D2-2), and specific diamine (D2-3) is preferably 97 mol% or less, and more preferably 95 mol% or less, relative to the total amount of diamine-derived structural units in polymer (P).

[0060] X in equation (1) above 1 , X in equation (2) above 2 , X in equation (3) above 3 and X in formula (4) above 4 The tetravalent group represented by is a structural unit derived from tetracarboxylic anhydride. Examples of tetracarboxylic anhydride include aliphatic tetracarboxylic dianhydride and aromatic tetracarboxylic dianhydride. Examples of aliphatic tetracarboxylic dianhydride include linear tetracarboxylic dianhydride and alicyclic tetracarboxylic dianhydride.

[0061] Examples of linear tetracarboxylic dianhydrides include 1,2,3,4-butanetetracarboxylic dianhydride and ethylenediaminetetraacetic acid dianhydride. Examples of alicyclic tetracarboxylic dianhydrides include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 5-(2,5-dioxotetrahydrofuran-3-yl)-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, and 5-(2,5-dioxotetrahydride Examples of dianhydrides include rofuran-3-yl)-8-methyl-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 2,4,6,8-tetracarboxybicyclo[3.3.0]octane-2:4,6:8-dianhydride, cyclopentanetetracarboxylic acid dianhydride, cyclohexanetetracarboxylic acid dianhydride, etc., and 3,5,6-tricarboxy-2-carboxymethylnorbornane-2:3,5:6-dianhydride. Examples of aromatic tetracarboxylic acid dianhydrides include pyromellitic acid dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic acid anhydride, ethylene glycol bisanhydrotrimate, 4,4'-carbonyl diphthalic acid anhydride, and 3,3',4,4'-biphenyltetracarboxylic acid dianhydride.

[0062] The tetracarboxylic dianhydrides constituting each substructure (U1), (U2-1) to (U2-3) preferably contain structural units derived from aromatic tetracarboxylic dianhydrides, as this has a high effect in improving the DC relaxation characteristics of the liquid crystal element and allows for the production of a liquid crystal element with sufficiently reduced afterimages. In polymer (P), the proportion of structural units derived from aromatic tetracarboxylic dianhydrides is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more, relative to the total amount of structural units derived from tetracarboxylic dianhydrides constituting polymer (P).

[0063] [Other diamines] In the synthesis of polymer (P), diamines other than the specified diamine (D1), specified diamine (D2-1), specified diamine (D2-2), and specified diamine (D2-3) (hereinafter also referred to as "other diamines") may be used in combination. Examples of other diamine compounds include aliphatic diamines, aromatic diamines, and diaminoorganosiloxanes. Examples of aliphatic diamines include linear diamines and alicyclic diamines.

[0064] Other specific examples of diamines include linear diamines such as metaxylylenediamine and hexamethylenediamine. Examples of alicyclic diamines include 1,4-diaminocyclohexane and 4,4'-methylenebis(cyclohexylamine).

[0065] Aromatic diamines include p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4-aminophenyl-4-aminobenzoate, 4,4'-diaminoazobenzene, 1,5-bis(4-aminophenoxy)pentane, 1,2-bis(4-aminophenoxy)ethane, 1,3-bis(4-aminophenoxy)propane, 1,6-bis(4-aminophenoxy)hexane, and 6,6'-(pentamethylenedioxy)bis(3-aminopyridinyl Main-chain diamines such as bis[2-(4-aminophenyl)ethyl]hexanediic acid, 4,4'-diaminodiphenyl ether, 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, and 4,4'-(phenylenediisopropylidene)bisaniline; Hexadecanoxy-2,4-diaminobenzene, Octadecanoxy-2,4-diaminobenzene, Octadecanoxy-2,5-diaminobenzene, Cholestanyloxy-3,5-diaminobenzene, Cholesteryloxy-3,5-diaminobenzene, Cholestanyloxy-2,4-diaminobenzene, Cholesteryloxy-2,4-diaminobenzene, Cholestanyl 3,5-diaminobenzoate, Cholesteryl 3,5-diaminobenzoate , 3,5-Lanostanyl diaminobenzoate, 3,6-Bis(4-aminobenzoyloxy)cholestane, 3,6-Bis(4-aminophenoxy)cholestane, 4-(4'-Trifluoromethoxybenzoyloxy)cyclohexyl-3,5-diaminobenzoate, 1,1-Bis(4-((aminophenyl)methyl)phenyl)-4-butylcyclohexane, 3,5-diaminobenzoate=5ξ-cholestane-3-yl, formula (E-1) [ka] (In formula (E-1), X I and X II These are, independently, a single bond, -O-, *-COO-, or *-OCO- (where "*" indicates a bond with the diaminophenyl group). I This is an alkanediyl group with 1 to 3 carbon atoms. II R is a single bond or an alkanediyl group having 1 to 3 carbon atoms. III (where a is an alkyl group, alkoxy group, fluoroalkyl group, or fluoroalkoxy group having 1 to 20 carbon atoms. a is 0 or 1. b is an integer between 0 and 3. c is an integer between 0 and 2. d is 0 or 1. However, 1 ≤ a + b + c ≤ 3.) Side-chain diamines such as compounds represented by, Examples of diaminoorganosiloxanes include 1,3-bis(3-aminopropyl)-tetramethyldisiloxane.

[0066] Examples of compounds represented by formula (E-1) include those represented by formulas (E-1-1) to (E-1-4) below. [ka]

[0067] In the synthesis of polymer (P), the proportion of other diamines used is preferably 75 mol% or less, and more preferably 65 mol% or less, relative to the total amount of diamines used in the synthesis of polymer (P).

[0068] [Synthesis of polymers (P)] • Polyamic acid When the polymer (P) is a polyamic acid, the polyamic acid (hereinafter also referred to as "polyamic acid (P)") can be obtained by reacting a tetracarboxylic dianhydride with a diamine, along with a molecular weight modifier as needed.

[0069] In the synthesis reaction of polyamic acid (P), the ratio of tetracarboxylic dianhydride to diamine is preferably such that the acid anhydride groups of the tetracarboxylic dianhydride are 0.2 to 2 equivalents per 1 equivalent of the amino groups of the diamine. Examples of molecular weight modifiers include acid monoanhydrides such as maleic anhydride, phthalic anhydride, and itaconic anhydride; monoamine compounds such as aniline, cyclohexylamine, and n-butylamine; and monoisocyanate compounds such as phenyl isocyanate and naphthyl isocyanate. The ratio of molecular weight modifier used is preferably 20 parts by mass or less per 100 parts by mass of the total amount of tetracarboxylic dianhydride and diamine used.

[0070] In the synthesis reaction of polyamic acid (P), the reaction temperature is preferably -20°C to 150°C, and the reaction time is preferably 0.1 to 24 hours. Examples of organic solvents used in the reaction include aprotic polar solvents, phenolic solvents, alcoholic solvents, ketone solvents, esteric solvents, etheric solvents, halogenated hydrocarbons, and hydrocarbons. Of these, it is preferable to use one or more selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide, m-cresol, xylenol, and halogenated phenol as the reaction solvent, or to use a mixture of one or more of these and other organic solvents (e.g., butyl cellosolve, diethylene glycol diethyl ether, etc.). The amount of organic solvent used is preferably such that the total amount of tetracarboxylic dianhydride and diamine compound is 0.1 to 50% by mass of the total amount of the reaction solution.

[0071] When a polymer solution is obtained by dissolving polyamic acid (P) through the above polymerization, this polymer solution may be used directly for the preparation of the liquid crystal alignment agent, or the polyamic acid (P) contained in the polymer solution may be isolated before being used for the preparation of the liquid crystal alignment agent.

[0072] • Polyamic acid esters When the polymer (P) is a polyamic acid ester, the polyamic acid ester can be obtained, for example, by [I] reacting polyamic acid (P) with an esterifying agent, [II] reacting a tetracarboxylic acid diester with a diamine, or [III] reacting a tetracarboxylic acid dihalide with a diamine. The polyamic acid ester may have only an amic acid ester structure, or it may be a partially esterified product in which both an amic acid structure and an amic acid ester structure coexist. The reaction solution obtained by dissolving the polyamic acid ester may be used as is for the preparation of the liquid crystal alignment agent. Alternatively, the polyamic acid ester contained in the reaction solution may be isolated, and the isolated polyamic acid ester may be used for the preparation of the liquid crystal alignment agent.

[0073] Polyimide When the polymer (P) is a polyimide, the polyimide (hereinafter also referred to as "polyimide (P)") can be obtained, for example, by dehydrating and cyclizing a polyamic acid (P) to imidize it. The imidization rate of polyimide (P) is preferably 20 to 99%, and more preferably 30 to 90%. The imidization rate is expressed as a percentage of the ratio of the number of imid ring structures to the total number of amic acid structures and imid ring structures in the polyimide.

[0074] Dehydration and ring closure of polyamic acid (P) is preferably carried out by dissolving the polyamic acid (P) in an organic solvent, adding a dehydrating agent and a dehydration and ring closure catalyst to the solution, and heating as necessary. In this method, acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride can be used as the dehydrating agent. The amount of dehydrating agent used is preferably 0.01 to 20 moles per mole of the amic acid structure of polyamic acid (P). Tertiary amines such as pyridine, colidine, lutidine, and triethylamine can be used as the dehydration and ring closure catalyst. The amount of dehydration and ring closure catalyst used is preferably 0.01 to 10 moles per mole of the dehydrating agent used.

[0075] Examples of organic solvents used in the dehydration and ring-closing reaction include those exemplified for use in the synthesis of polyamic acid (P). The reaction temperature for the dehydration and ring-closing reaction is preferably 0 to 180°C. The reaction time is preferably 1.0 to 120 hours. The reaction solution containing polyimide (P) may be used directly for the preparation of the liquid crystal alignment agent. Alternatively, polyimide (P) may be isolated from the reaction solution and the isolated polyimide (P) may be used for the preparation of the liquid crystal alignment agent. Polyimide (P) can also be obtained by dehydration and ring-closing of polyamic acid esters.

[0076] The solution viscosity of the polymer (P) is preferably 10 to 800 mPa·s when it is a 10% by mass solution, and more preferably 15 to 500 mPa·s. The solution viscosity (mPa·s) is the value measured at 25°C using an E-type rotational viscometer for a 10% by mass polymer solution prepared using a good solvent for the polymer (P) (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

[0077] The weight-average molecular weight (Mw) of the polymer (P), measured by gel permeation chromatography (GPC) in terms of polystyrene, is preferably 1,000 to 500,000, and more preferably 2,000 to 300,000. The molecular weight distribution (Mw / Mn), expressed as the ratio of Mw to the number-average molecular weight (Mn) measured by GPC in terms of polystyrene, is preferably 7 or less, and more preferably 5 or less.

[0078] The content of polymer (P) in the liquid crystal alignment agent is preferably 20% by mass or more, more preferably 40% by mass or more, and even more preferably 60% by mass or more, based on the total amount of solids contained in the liquid crystal alignment agent (i.e., the total mass of components other than the solvent in the liquid crystal alignment agent).

[0079] <Other ingredients> The liquid crystal alignment agent may contain, in addition to the polymer (P), components other than the polymer (P) as needed (hereinafter also referred to as "other components").

[0080] • Polymer (Q) The liquid crystal alignment agent of this disclosure may further contain a polymer (Q) different from polymer (P). By combining polymer (Q) with polymer (P), a liquid crystal alignment film can be formed that provides a liquid crystal element with good liquid crystal alignment properties and high reliability.

[0081] The main skeleton of polymer (Q) is not particularly limited. Examples of polymer (Q) include polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane, polyester, polyenamine, polyurea, polyamide, polyamideimide, polybenzoxazole precursor, polybenzoxazole, cellulose derivative, polyacetal, and addition polymers (e.g., (meth)acrylic polymers, styrene polymers, maleimide polymers, styrene-maleimide copolymers). Of these, polymer (Q) is preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide. When polymer (Q) is at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide, polymer (Q) is a polymer that does not have a substructure (U1).

[0082] The liquid crystal alignment agent of this disclosure preferably contains a polymer (Q) having at least one selected from the group consisting of a substructure represented by the following formula (5) and a substructure represented by the following formula (6) (hereinafter also referred to as "polymer (Q-1)"). Including polymer (Q-1) together with polymer (P) in the liquid crystal alignment agent is preferable because it can promote layer separation of polymer components and improve liquid crystal alignment. [ka] (In equations (5) and (6), X 5 and X 6 These are, independently, tetravalent groups having an alicyclic structure. 5 and Y 6These are divalent organic groups, each independently containing a substructure in which a thermally leaveable group is bonded to a nitrogen atom.

[0083] In equations (5) and (6) above, X 5 and X 6 The tetravalent group represented by is a group derived from a tetracarboxylic dianhydride having an alicyclic structure (i.e., an alicyclic tetracarboxylic dianhydride). Specific examples of alicyclic tetracarboxylic dianhydrides include compounds similar to those exemplified as alicyclic tetracarboxylic dianhydrides constituting polymer (P). 5 and X 6 The alicyclic structure possessed by is preferably a substituted or unsubstituted cyclobutane ring structure.

[0084] In the substituted cyclobutane ring structure, examples of substituents include C1-C6 alkyl groups, C1-C6 halogenated alkyl groups, C1-C6 alkoxy groups, C1-C6 halogenated alkoxy groups, and halogen atoms. Of these, the substituents on the cyclobutane ring structure are preferably C1-C3 alkyl groups, C1-C3 halogenated alkyl groups, C1-C3 alkoxy groups, C1-C3 halogenated alkoxy groups, or halogen atoms, more preferably C1-C3 alkyl groups, C1-C3 fluoroalkyl groups, or fluorine atoms, and particularly preferably methyl groups.

[0085] X 5 and X 6Specific examples of tetracarboxylic dianhydrides that constitute the tetravalent group represented by include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1-methyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3-trimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1-ethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-diethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1-ethyl-3-methyl-1, Examples include 2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethoxy-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-diethoxy-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1-trifluoromethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-di(trifluoromethyl)-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-di(trifluoromethoxy)-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3-tri(trifluoromethyl)-1,2,3,4-cyclobutanetetracarboxylic dianhydride, and 1,2,3,4-tetra(trifluoromethyl)-1,2,3,4-cyclobutanetetracarboxylic dianhydride. Of these, at least one selected from the group consisting of 1,2,3,4-cyclobutanetetracarboxylic dianhydride and 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride is preferred.

[0086] Y 5 and Y 6 The divalent organic group represented by is a group derived from a diamine having a substructure (hereinafter also referred to as "substructure (Np)") in which a thermally leaving group is bonded to a nitrogen atom. A specific example of the thermally leaving group possessed by substructure Np is A in formula (1) above. 3 In the explanation of A 3Examples of groups that are thermally leaving groups include those similar to the group exemplified above. Among the thermally leaving groups of the substructure Np, the tert-butoxycarbonyl group is preferred.

[0087] The polymer (Q-1) may have the substructure Np in the main chain, in the side chain, or in both. Specific examples of the substructure Np include a monovalent group represented by formula (Np-1) and a divalent group represented by formula (Np-2). [ka] (In equations (Np-1) and (Np-2), R 10 R is a thermally leaving group. 11 This is a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a thermally desorbable group. "*" represents a bond. 2 (This symbol represents a bond with an atom that makes up the main chain.)

[0088] Specific examples of diamines having a substructure (Np) include compounds represented by the following formula. [ka]

[0089] When polymer (Q) is included in the liquid crystal alignment agent, the content of polymer (Q) is preferably 5 parts by mass or more, and more preferably 10 parts by mass or more, based on 100 parts by mass of the total amount of polymer (P) and polymer (Q) contained in the liquid crystal alignment agent. Furthermore, the content of polymer (Q) is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 40% by mass or less, based on 100 parts by mass of the total amount of polymer (P) and polymer (Q) contained in the liquid crystal alignment agent.

[0090] The content of polymer (Q-1) is preferably 5 parts by mass or more, and more preferably 10 parts by mass or more, based on 100 parts by mass of the total amount of polymer (P) and polymer (Q) contained in the liquid crystal alignment agent. Furthermore, the content of polymer (Q-1) is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 40% by mass or less, based on 100 parts by mass of the total amount of polymer (P) and polymer (Q) contained in the liquid crystal alignment agent.

[0091] • Crosslinking agent The liquid crystal alignment agent of this disclosure may contain a crosslinking agent for purposes such as improving the mechanical strength of the film. Preferably, a compound (hereinafter also referred to as "compound (Z)") having three or more crosslinkable groups in one molecule, selected from the group consisting of oxiranil groups, oxetanil groups, hydroxyl groups, mercapto groups, amino groups, and polymerizable carbon-carbon double bond groups, can be used as the crosslinking agent. From the viewpoint of improving the mechanical strength of the film while ensuring the toughness of the film, the number of crosslinkable groups in compound (Z) is preferably 3 to 10, and more preferably 3 to 6.

[0092] When compound (Z) is included in the liquid crystal alignment agent, the content of compound (Z) is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, per 100 parts by mass of the total amount of polymer components (total amount of polymer (P) and polymer (Q)) contained in the liquid crystal alignment agent. Furthermore, the content of compound (Z) is preferably 15 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of the total amount of polymer components contained in the liquid crystal alignment agent.

[0093] • Adhesion enhancer The liquid crystal alignment agent of this disclosure may contain an adhesion aid for the purpose of improving the adhesion of the liquid crystal alignment film. A compound having a trialkoxysilyl group (hereinafter also referred to as "compound (Y)") can preferably be used as the adhesion aid. Compound (Y) is preferably a compound having at least one reactive functional group selected from the group consisting of an oxiranil group, an oxetanil group, a hydroxyl group, a mercapto group, an amino group, and a polymerizable carbon-carbon double bond group. As such compound (Y), known silane coupling agents having the above-mentioned reactive functional groups can be appropriately used.

[0094] When compound (Y) is included in the liquid crystal alignment agent, the content of compound (Y) is preferably 0.1 parts by mass or more, and more preferably 0.3 parts by mass or more, per 100 parts by mass of the total amount of polymer components (total amount of polymer (P) and polymer (Q)) contained in the liquid crystal alignment agent. Furthermore, the content of compound (Y) is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of the total amount of polymer components contained in the liquid crystal alignment agent.

[0095] ·solvent The liquid crystal alignment agent of this disclosure is prepared as a liquid composition comprising a polymer (P) and other components used as needed, preferably dispersed or dissolved in a suitable solvent.

[0096] Organic solvents are preferred as solvents. Specific examples include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,2-dimethyl-2-imidazolidinone, 1,3-dimethyl-2-imidazolidinone, phenol, γ-butyrolactone, γ-butyrolactam, 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, methyl acetoacetate, ethyl acetoethyl acetate, ethyl propionate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, and ethylene glycol-i-propyl ether. Examples of solvents include ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisopentyl ether, ethylene carbonate, propylene carbonate, propylene glycol monomethyl ether (PGME), diethylene glycol diethyl ether acetate, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol diacetate, cyclopentanone, and cyclohexanone. As solvents, one type can be used alone or two or more types can be used in combination.

[0097] Other components that can be incorporated into the liquid crystal alignment agent include, in addition to those mentioned above, antioxidants, metal chelating compounds, curing accelerators, surfactants, fillers, dispersants, photosensitizers, and the like. The proportion of these other components can be appropriately selected depending on the compound, as long as it does not impair the effects of the present disclosure.

[0098] The solid content concentration in the liquid crystal alignment agent (the ratio of the total mass of components other than the solvent to the total mass of the liquid crystal alignment agent) is appropriately selected considering viscosity, volatility, etc. The solid content concentration of the liquid crystal alignment agent is preferably in the range of 1 to 10% by mass. A solid content concentration of 1% by mass or more is preferable because it allows for sufficient film thickness of the coating and enables the production of a liquid crystal alignment film exhibiting better liquid crystal alignment properties. On the other hand, a solid content concentration of 10% by mass or less allows for a coating film of appropriate thickness, making it easier to obtain a liquid crystal alignment film exhibiting good liquid crystal alignment properties, and the viscosity of the liquid crystal alignment agent tends to be appropriate, resulting in good coatability.

[0099] <Liquid crystal alignment films and liquid crystal elements> The liquid crystal alignment film of this disclosure is manufactured using a liquid crystal alignment agent prepared as described above. The liquid crystal element of this disclosure comprises a liquid crystal alignment film formed using the liquid crystal alignment agent described above. The liquid crystal driving method 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-PVA type, etc.), IPS type, FFS type, OCB (Optically Compensated Bend) type, and PSA type (Polymer Sustained Alignment). The liquid crystal element can be manufactured by a method including, for example, the following steps 1 to 3. In step 1, the substrate used differs depending on the desired operating mode. Steps 2 and 3 are common to each operating mode.

[0100] <Step 1: Formation of the coating> First, a liquid crystal alignment agent is applied to the substrate, and preferably the applied surface is heated to form a coating on the substrate. As the substrate, for example, glass such as float glass or soda glass; or transparent substrates made of plastics such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, or poly(alicyclic olefin) can be used. As the transparent conductive film provided on one side of the substrate, a NESA film (registered trademark of PPG, Inc., USA) made of tin oxide (SnO2), or an ITO film made of indium oxide-tin oxide (In2O3-SnO2) can be used. When manufacturing TN, STN, or VA type liquid crystal elements, two substrates with patterned transparent conductive films are used. On the other hand, when manufacturing IPS or FFS type liquid crystal elements, a substrate with comb-shaped patterned electrodes and a counter substrate without electrodes are used.

[0101] The method for applying the liquid crystal alignment agent to the substrate is not particularly limited. The liquid crystal alignment agent can be applied to the substrate by, for example, a spin coating method, a printing method (e.g., offset printing method, flexographic printing method, etc.), an inkjet method, a slit coating method, a bar coater method, an extrusion die method, a direct gravure coater method, a chamber doctor coater method, an offset gravure coater method, an impregnation coater method, an MB coater method, etc.

[0102] After applying the liquid crystal alignment agent, preheating (pre-bake) is preferably performed to prevent dripping of the applied liquid crystal alignment agent. The pre-bake temperature is preferably 30 to 200°C, and the pre-bake time is preferably 0.25 to 10 minutes. After that, a firing (post-bake) step is performed to completely remove the solvent and, if necessary, to thermally imide the amic acid structure present in the polymer. The firing temperature (post-bake temperature) at this time is preferably 80 to 280°C, more preferably 80 to 250°C. The post-bake time is preferably 5 to 200 minutes. The film thickness of the formed film is preferably 0.001 to 1 μm.

[0103] <Step 2: Orientation Treatment> When manufacturing TN, STN, IPS, or FFS type liquid crystal elements, the coating film formed in step 1 is subjected to a process (alignment treatment) to impart liquid crystal alignment ability. This imparts the liquid crystal molecule alignment ability to the coating film, making it a liquid crystal alignment film. As the alignment treatment, it is preferable to use a rubbing treatment in which the surface of the coating film formed on the substrate is rubbed with cotton or nylon, or a photo-alignment treatment in which the coating film is irradiated with light to impart liquid crystal alignment ability. When manufacturing vertically aligned liquid crystal elements, the coating film formed in step 1 may be used as is as a liquid crystal alignment film, or an alignment treatment may be applied to the coating film to further enhance its liquid crystal alignment ability. A liquid crystal alignment film suitable for vertically aligned liquid crystal elements can also be preferably used for PSA type liquid crystal elements.

[0104] Light irradiation for photo-alignment can be carried out by methods such as irradiating the coating film after the post-bake process, irradiating the coating film after the pre-bake process but before the post-bake process, or irradiating the coating film while it is being heated in at least one of the pre-bake or post-bake processes. As radiation to irradiate the coating film, for example, ultraviolet light and visible light including light with wavelengths of 150 to 800 nm can be used. Preferably, ultraviolet light including light with wavelengths of 200 to 400 nm is used. If the radiation is polarized, it may be linearly polarized or partially polarized. If the radiation used is linearly polarized or partially polarized, irradiation may be carried out from a direction perpendicular to the substrate surface, from an oblique direction, or a combination of these. In the case of unpolarized radiation, the irradiation direction should be oblique.

[0105] Examples of light sources that can be used include low-pressure mercury lamps, high-pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonance lamps, xenon lamps, and excimer lasers. The radiation dose is preferably 200 to 30,000 J / m². 2 And more preferably, 500~10,000 J / m 2In addition, after light irradiation to impart orientation ability, the substrate surface may be washed with, for example, water, an organic solvent (e.g., methanol, isopropyl alcohol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, etc.), or a mixture thereof, or the substrate may be heated.

[0106] <Step 3: Liquid Crystal Cell Construction> A liquid crystal cell is manufactured by preparing two substrates on which a liquid crystal alignment film is formed as described above, and placing liquid crystal between the two substrates which are placed opposite each other. Methods for manufacturing a liquid crystal cell include, for example, placing two substrates opposite each other with a gap in between so that the liquid crystal alignment films face each other, bonding the periphery of the two substrates with a sealant, injecting and filling the cell gap surrounded by the substrate surface and the sealant, and sealing the injection hole, or the ODF method. As the sealant, for example, an epoxy resin containing a curing agent and aluminum oxide spheres as spacers can be used. Examples of liquid crystals include nematic liquid crystals and smectic liquid crystals, with nematic liquid crystals being preferred.

[0107] In PSA mode, a polymerizable compound (e.g., a polyfunctional (meth)acrylate compound) is packed into the cell gap along with the liquid crystal, and after the liquid crystal cell is constructed, a voltage is applied between the conductive films of a pair of substrates, and the liquid crystal cell is irradiated with light. When manufacturing a PSA type liquid crystal element, the proportion of polymerizable compound used is, for example, 0.01 to 3 parts by mass, preferably 0.05 to 1 part by mass, per 100 parts by mass of the total liquid crystal.

[0108] When manufacturing liquid crystal display devices, a polarizing plate is then bonded to the outer surface of the liquid crystal cell. Examples of polarizing plates include a polarizing film called an "H film," which is made by stretching and oriented polyvinyl alcohol while absorbing iodine, sandwiched between cellulose acetate protective films, or a polarizing plate made of the H film itself.

[0109] The liquid crystal elements of this disclosure can be effectively applied to a variety of uses. Specifically, they can be used, for example, in various display devices such as watches, portable game consoles, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, liquid crystal televisions, information displays, as well as in dimming devices, phase difference films, and the like. [Examples]

[0110] The present invention will be described in more detail below with reference to examples, but it is not limited to these examples.

[0111] <Structure and abbreviation of the compound> The main compounds used in the following examples have structures and abbreviations as follows:

[0112] [Tetracarboxylic acid dianhydride] Compounds (TA-1) to (TA-7); compounds represented by the following formulas (TA-1) to (TA-7). [ka]

[0113] [Diamine] Compounds (DA-1) to (DA-6); compounds represented by the following formulas (DA-1) to (DA-6). [ka]

[0114] Compounds (DB-1) to (DB-6); compounds represented by the following formulas (DB-1) to (DB-6). [ka]

[0115] Compounds (DC-1), (DC-2); compounds represented by the following formulas (DC-1) or (DC-2).

Chem.

[0116] Compound (DD-1) to Compound (DD-4); compounds respectively represented by the following formulae (DD-1) to (DD-4)

Chem.

[0117] Compound (DE-1) to Compound (DE-13); compounds respectively represented by the following formulae (DE-1) to (DE-13)

Chem.

Chem.

[0118] [Additive] Compound (AD-1) to Compound (AD-4); compounds respectively represented by the following formulae (AD-1) to (AD-4)

Chem.

[0119] [Solvent] NMP; N-methyl-2-pyrrolidone BC; butyl cellosolve

[0120] <Synthesis and Evaluation of Polymers> Polymers were respectively synthesized in the following Synthesis Examples 1 to 52. In the following examples, the imidization ratio of polyimide in the polymer solution was measured by the method below. [Imidization Ratio of Polyimide] A polyimide solution was poured into pure water, the obtained precipitate was sufficiently dried under reduced pressure at room temperature, then dissolved in deuterated dimethyl sulfoxide, and measured at room temperature with tetramethylsilane as a reference substance for 1 H-NMR measurement. The obtained 1The imidization rate [%] was determined from the 1H-NMR spectrum (400 MHz) using the following formula (1). Imidization rate [%] = (1 - (A1 / (A2 × α))) × 100 …(1) (In formula (1), A1 is the peak area derived from the proton of the amide group appearing around a chemical shift of 10 ppm, A2 is the peak area derived from the proton of the aromatic group appearing around a chemical shift of 6-9 ppm, and α is the ratio of the number of protons of the aromatic group to one proton of the amide group in the polymer precursor (polyamic acid).)

[0121] [Synthesis Example 1] Diamines (10 moles of diamine (DA-1), 40 moles of diamine (DB-2), 20 moles of diamine (DC-1), and 30 moles of diamine (DE-3) per 100 moles of total diamines) were dissolved in NMP, and 0.95 mole equivalents of tetracarboxylic dianhydride (40 moles of acid dianhydride (TA-1) and 60 moles of acid dianhydride (TA-5) per 100 moles of total tetracarboxylic dianhydride) were added relative to the total amount of diamines. The reaction was carried out at room temperature for 6 hours to obtain a 15% by mass solution of polyamic acid (referred to as polymer (PA-1)).

[0122] [Synthesis Examples 2-32] Polyamic acids (polymers (PA-2) to (PA-32)) were obtained in the same manner as in Synthesis Example 1, except that the types and molar ratios of tetracarboxylic dianhydride and diamine were changed as shown in Table 1 below.

[0123] [Synthesis Examples 33-38] Polyamic acids (polymers (PA-32) to (PA-38)) were obtained in the same manner as in Synthesis Example 1, except that the types and molar ratios of tetracarboxylic dianhydride and diamine were changed as shown in Table 2 below.

[0124] [Synthesis Example 39] Diamines (50 moles of diamine (DE-11), 30 moles of diamine (DE-12), and 20 moles of diamine (DE-2) per 100 moles of total diamines) were dissolved in NMP, and 0.95 mole equivalents of tetracarboxylic dianhydride (TA-2) relative to the total amount of diamines were added. The reaction was carried out at room temperature for 6 hours to obtain a polyamic acid solution. To the obtained solution, 0.75 mole equivalents of 1-methylpiperidine and acetic anhydride relative to the carboxyl groups of the polyamic acid were added as dehydrating agents, and the mixture was heated and stirred at 60°C for 3 hours. The obtained solution was repeatedly concentrated under reduced pressure and diluted with NMP to obtain a 10% by mass solution of polyimide (referred to as polymer (PI-1)). The imidization rate of polyimide (PI-1) was 78%.

[0125] [Synthesis Example 40] Polyimide (referred to as polymer (PI-2)) was obtained in the same manner as in Synthesis Example 39, except that the types and molar ratios of tetracarboxylic dianhydride and diamine were changed as shown in Table 2 below.

[0126] [Synthesis Examples 41-51] Polyamic acids (polymers (PA-39) to (PA-49)) were obtained in the same manner as in Synthesis Example 1, except that the types and molar ratios of tetracarboxylic dianhydride and diamine were changed as shown in Table 3 below. [Synthesis Example 52] A 10% by mass solution of the polyimide polymer (PI-3) was obtained in the same manner as in Synthesis Example 39, except that the molar ratio of the dehydrating agent was changed to 0.40 molar equivalents. The imidization rate of the polymer (PI-3) was 50%.

[0127] [Table 1]

[0128] [Table 2]

[0129] [Table 3]

[0130] In Tables 1 to 3, for tetracarboxylic dianhydrides, the numerical values indicate the proportion (mol%) of each compound used relative to the total amount (100 mol%) of the tetracarboxylic dianhydride used in the synthesis, and for diamines, the numerical values indicate the proportion (mol%) of each compound used relative to the total amount (100 mol%) of the diamine used in the synthesis.

[0131] <Preparation and Evaluation of Liquid Crystal Alignment Agents> [Example 1: Photo-alignment FFS-type Liquid Crystal Display Element] (1) Preparation of Liquid Crystal Alignment Agent A polymer component (in terms of solid content: 20 parts by mass of polymer (PI-1), 80 parts by mass of polymer (PA-1)), 5 parts by mass of a crosslinking agent (N,N,N',N'-tetrakis(2-hydroxyethyl)adipamide (compound represented by the above formula (AD-1))), and 1 part by mass of an adhesion aid (3-glycidyloxypropyltrimethoxysilane (compound represented by the above formula (AD-4))) were diluted with NMP and BC to obtain a solution having a solid concentration of 4.0% by mass and a solvent composition ratio of NMP:BC = 70:30 (mass ratio). This solution was filtered through a filter with a pore diameter of 0.2 μm to prepare a liquid crystal alignment agent (AL-1).

[0132] (2) Formation of Liquid Crystal Alignment Film by Photoalignment Method The liquid crystal alignment agent (AL-1) prepared in (1) above was applied onto the respective surfaces of a glass substrate having a flat electrode, an insulating layer, and a comb-shaped electrode laminated in this order on one side, and a counter glass substrate provided with no electrodes, using a spin coater. After heating on a hot plate at 80°C for 1 minute, heating was performed for 30 minutes in an oven at 230°C whose interior was replaced with nitrogen to form a coating film with an average film thickness of 100 nm. To the surface of this coating film, using an Hg-Xe lamp, 200 mJ / cm 2 of ultraviolet light containing linearly polarized 254 nm emission line was irradiated from the direction normal to the substrate to perform photoalignment treatment. The coating film subjected to this photoalignment treatment was heat-treated by heating for 30 minutes in an oven at 230°C whose interior was replaced with nitrogen to form a liquid crystal alignment film.

[0133] (3) Manufacturing of FFS type liquid crystal display elements 2) above, an epoxy resin adhesive containing 3.5 μm diameter aluminum oxide spheres was dispensed onto the outer periphery of one of the substrates having a liquid crystal alignment film, leaving a liquid crystal injection port. Then, the surfaces of the pair of substrates having liquid crystal alignment films were placed facing each other and pressed together so that the alignment processing directions of each substrate were opposite parallel. The adhesive was then heat-cured at 150°C for 1 hour. Next, negative nematic liquid crystal (Merck, MJ20195NCMP) was filled into the gap between the substrates through the liquid crystal injection port, and the liquid crystal injection port was sealed with epoxy adhesive. Furthermore, to remove the flow alignment during liquid crystal injection, it was heated at 120°C and then slowly cooled to room temperature. Next, polarizing plates were bonded to both outer surfaces of the substrate so that their polarization directions were orthogonal to each other and formed a 45° angle with the alignment processing direction of the liquid crystal alignment film, thereby manufacturing an FFS type liquid crystal display element.

[0134] (4) Evaluation of liquid crystal alignment The liquid crystal display elements manufactured in (4) above were observed under a microscope at 50x magnification to check for the presence or absence of abnormal domains in the change in brightness when a 5V voltage was turned ON and OFF (applied and released). The evaluation was "good" if no abnormal domains were observed and "poor" if abnormal domains were observed. As a result, this embodiment was evaluated as "good".

[0135] (5) Evaluation of long-term afterimage at room temperature (DC relaxation characteristics) The liquid crystal display element manufactured in (4) above was placed in an environment of 25°C and 1 atmosphere. After setting the brightness difference between any two pixels to 0 by driving with a 30Hz AC square wave at 100% relative transmittance, a DC (0.5V) was applied to only one pixel for 30 minutes while AC driving under backlight illumination to accumulate charge. When the application of DC 0.5V was terminated and the drive was returned to AC only, resulting in a relative transmittance of 50%, a brightness difference ΔL was generated between the two pixels due to the accumulated charge. The change in this brightness difference ΔL over time was observed, and the time from the termination of DC 0.5V application until the brightness difference ΔL fell below 36.8% of the initial value was defined as the afterimage erasure time. Note that the shorter this time, the easier it is for the afterimage due to accumulated charge to disappear, and the better the DC relaxation characteristics. The evaluation criteria were as follows: "Excellent" if the afterimage erasure time was less than 10 minutes, "Good" if it was between 10 and 20 minutes, "Acceptable" if it was between 20 and 30 minutes, and "Poor" if it was 30 minutes or more. As a result, this example received an evaluation of "Good".

[0136] (6) Evaluation of high-temperature short-term afterimage (DC accumulation characteristics) The liquid crystal display element manufactured in (4) above was placed in an environment of 60°C and 1 atmosphere. After driving it with a 30Hz AC square wave at 100% relative transmittance to set the brightness difference between any two pixels to 0, a DC (direct current) of 0.2V was applied to only one pixel for 30 minutes while AC driving under backlight illumination to accumulate charge. When the application of DC 0.2V was terminated and the drive was returned to AC only, resulting in a relative transmittance of 50%, a brightness difference ΔL was generated between the two pixels due to the accumulated charge. Note that the smaller this brightness difference, the less charge is accumulated, and the better the DC accumulation characteristics are considered to be. If the value obtained by dividing this brightness difference ΔL by the average brightness of the two pixels was less than 1%, it was rated as "Excellent"; if it was between 1% and 2%, it was rated as "Good"; if it was between 2% and 3%, it was rated as "Acceptable"; and if it was 3% or more, it was rated as "Unacceptable". As a result, this embodiment was rated as "Acceptable".

[0137] [Examples 2-17, Examples 26-29] In Example 1 described above, the liquid crystal alignment agent was prepared in the same manner as in Example 1, except that the type and amount of polymer components contained in the liquid crystal alignment agent were changed as shown in Table 4 below. A liquid crystal alignment film was formed by photoalignment, and an FFS-type liquid crystal display element was manufactured and various evaluations were performed. The evaluation results are shown in Table 4 below. The exposure amount of linearly polarized ultraviolet light was 200 mJ / cm² in Examples 2-4, 10-11, 13-17, 26, and 28-29. 2 In other examples, the concentration was 500 mJ / cm². 2 That's what I decided.

[0138] [Comparative Examples 1-14] In Example 1 described above, the liquid crystal alignment agent was prepared in the same manner as in Example 1, except that the type and amount of polymer components contained in the liquid crystal alignment agent were changed as shown in Table 5 below. A liquid crystal alignment film was formed by photoalignment, and an FFS-type liquid crystal display element was manufactured and various evaluations were performed. The evaluation results are shown in Table 5 below. The exposure amount of linearly polarized ultraviolet light was 200 mJ / cm² in Comparative Examples 1 to 12. 2 In comparative examples 13 and 14, the concentration was 500 mJ / cm². 2 That's what I decided.

[0139] [Example 18: Rubbing-oriented FFS type liquid crystal display element] (1) Preparation of liquid crystal alignment agent A solution was obtained by diluting polymer components (based on solid content: polymer (PI-2) 20 parts by mass, polymer (PA-1) 80 parts by mass), a crosslinking agent (N,N,N',N'-tetrakis(2-hydroxyethyl)adipamide (compound represented by formula (AD-1) above)) 5 parts by mass, and an adhesion aid (3-glycidyloxypropyltrimethoxysilane (compound represented by formula (AD-4) above)) 1 part by mass with NMP and BC to obtain a solution with a solid content concentration of 4.0% by mass and a solvent composition ratio of NMP:BC = 70:30 (by mass ratio). A liquid crystal alignment agent (AL-18) was prepared by filtering this solution through a filter with a pore size of 0.2 μm.

[0140] (2) Formation of liquid crystal alignment film by rubbing method A glass substrate with a flat electrode, an insulating layer, and a comb-shaped electrode laminated in this order on one side, and a counter glass substrate without electrodes, were each coated with the liquid crystal alignment agent (AL-18) prepared in (1) above using a spin coater. The coated surfaces were heated on an 80°C hot plate for 1 minute, and then heated in a 230°C oven with nitrogen purging for 30 minutes to form a coating with an average thickness of 100 nm. The surface of this coating was then rubbed twice using a rubbing machine with a roll wrapped in nylon cloth, at a roll rotation speed of 1000 rpm, a stage movement speed of 30 mm / second, and a pile insertion length of 0.3 mm. The coating with this rubbing alignment treatment was ultrasonically cleaned in ultrapure water for 1 minute, and then dried in a 100°C oven for 10 minutes to form a liquid crystal alignment film.

[0141] (3) Manufacturing of FFS type liquid crystal display elements An FFS-type liquid crystal display element was manufactured in the same manner as in Example 1, except that a pair of substrates having liquid crystal alignment films prepared by the rubbing method described in (2) above were used as substrates having liquid crystal alignment films.

[0142] (4) Evaluation of liquid crystal alignment The FFS-type liquid crystal display element manufactured in (3) above was evaluated for liquid crystal alignment in the same manner as in Example 1. As a result, this example received a "good" evaluation.

[0143] (5) Evaluation of long-term afterimage at room temperature (DC relaxation characteristics) The DC relaxation characteristics of the FFS-type liquid crystal display element manufactured in (3) above were evaluated in the same manner as in Example 1. As a result, this example received a "good" evaluation.

[0144] (6) Evaluation of high-temperature short-term afterimage (DC accumulation characteristics) The DC storage characteristics of the FFS-type liquid crystal display element manufactured in (3) above were evaluated in the same manner as in Example 1. As a result, this example received a "good" rating.

[0145] [Examples 19-25] In Example 18, the liquid crystal alignment agent was prepared in the same manner as in Example 18, except that the type and amount of polymer components contained in the liquid crystal alignment agent were changed as shown in Table 4 below. A liquid crystal alignment film was formed by the rubbing method, and an FFS type liquid crystal display element was manufactured and various evaluations were performed. The evaluation results are shown in Table 4 below.

[0146] [Table 4]

[0147] [Table 5]

[0148] In Tables 4 and 5, the mass ratio of each polymer in the liquid crystal alignment agent indicates the blending ratio (parts by mass) of each polymer relative to 100 parts by mass of the total polymer components used in the preparation of the liquid crystal alignment agent. In each example of the liquid crystal alignment agent, a crosslinking agent (N,N,N',N'-tetrakis(2-hydroxyethyl)adipamide (a compound represented by formula (AD-1) above)) and an adhesion aid (3-glycidyloxypropyltrimethoxysilane (a compound represented by formula (AD-4) above)) were blended in 5 parts by mass and 1 part by mass, respectively, relative to 100 parts by mass of the total polymer components.

[0149] As shown in Table 4, the liquid crystal alignment agents of Examples 1 to 29 containing polymer (P) exhibited "good" liquid crystal alignment properties in the liquid crystal display elements, and both the long-term afterimage at room temperature (DC relaxation characteristics) and the short-term afterimage at high temperature (DC accumulation characteristics) were "excellent," "good," or "acceptable," demonstrating a good balance of various characteristics. In contrast, the liquid crystal alignment agents of Comparative Examples 1 to 14, which did not contain polymer (P), exhibited "unacceptable" DC relaxation characteristics and DC accumulation characteristics in the liquid crystal display elements, indicating inferiority compared to the examples.

[0150] In Examples 1 to 29, the mechanism by which the afterimage characteristics of the liquid crystal display elements were improved is not clear, but it is presumed to be as follows.

[0151] The polymers contained in the liquid crystal alignment agents of Examples 1 to 29 have a substructure (U1) (a substructure with hole transport properties), and also have any two or all of the three substructures: substructure (U2-1) (a substructure with hydrogen bonding properties), substructure (U2-2) (a substructure with an acidic functional group), and substructure (U2-3) (a substructure with a basic functional group). In contrast, the liquid crystal alignment agents of Comparative Examples 1 to 4 do not have a polymer with substructure (U1), the liquid crystal alignment agents of Comparative Examples 5 to 7 do not have any of substructures (U2-1), (U2-2), or (U2-3), and the liquid crystal alignment agents of Comparative Examples 8 to 14 have a polymer with only one of the three substructures (U2-1), (U2-2), or (U2-3).

[0152] From the viewpoint of long-term afterimage at room temperature (DC relaxation characteristics), it is preferable that the polymer has a substructure that exhibits hole transport properties, and more preferably that it has a substructure derived from an aromatic tetracarboxylic dianhydride. In the liquid crystal alignment agents of Examples 1 to 29, the polymer had a substructure (U1), and the evaluation of the DC relaxation characteristics was "acceptable" or better, whereas in the liquid crystal alignment agents of Comparative Examples 1 to 4, the polymer did not have a substructure (U1), and therefore the evaluation of the DC relaxation characteristics was "unacceptable."

[0153] From the viewpoint of high-temperature short-term afterimage (DC accumulation characteristics), it is preferable that the physical and electrical properties of the liquid crystal alignment film are stable and do not change easily at high temperatures and under backlight, and further, it is preferable that the movement and uneven distribution of ionic impurities in the liquid crystal cell are suppressed. In contrast, the liquid crystal alignment agents of Examples 1 to 29 had polymers that had two or all of the structural units of partial structure (U2-1), partial structure (U2-2), and partial structure (U2-3), and the evaluation of their DC accumulation characteristics was "acceptable" or better. In contrast, the liquid crystal alignment agents of Comparative Examples 5 to 14 had polymers that had only one of the partial structure (U2-1), partial structure (U2-2), and partial structure (U2-3), or none of them, and it is thought that the evaluation of their DC accumulation characteristics was "unacceptable".

[0154] In this regard, it is thought that the polymer having two or all of the structural units of substructure (U2-1), substructure (U2-2), and substructure (U2-3) strengthens the intermolecular interactions between polymers in the liquid crystal alignment film, suppressing liquid crystal swelling and thermal expansion, thereby suppressing fluctuations in physical and electrical properties at high temperatures and under backlight. Furthermore, it is thought that the diffusion of ionic impurities trapped in the liquid crystal alignment film into the liquid crystal layer and their movement due to the electric field are suppressed.

[0155] Furthermore, in polymer (P), it is thought that the amide bond or urea bond in substructure (U2-1) can act as hydrogen bond donors and acceptors, the carboxylic acid group or sulfonic acid group in substructure (U2-2) can act as hydrogen bond donors and acceptors, and the basic functional group in substructure (U2-3) can act as a hydrogen bond acceptor. In addition, when acidic and basic functional groups coexist, it is thought that intermolecular interactions can also be formed through acid-base interactions (ionic interactions).

[0156] From the viewpoint of liquid crystal alignment, it is preferable that the liquid crystal alignment agent contains polymer (P) and polymer (Q), with polymer (Q), which is mainly responsible for imparting and improving liquid crystal alignment, and polymer (P), which is mainly responsible for imparting and improving electrical properties, being separated into upper and lower layers. When the liquid crystal alignment agent includes polymer (Q-1), which has polar groups protected by Boc groups, along with polymer (P), the hydrophobicity of polymer (Q) increases, making it easier for polymer (P) to be unevenly distributed on the film surface, and thus easier to exhibit liquid crystal alignment. Furthermore, it is conceivable that the thermal desorption of Boc groups to generate polar groups may contribute to crosslinking between polymers and intermolecular interactions.

[0157] Furthermore, the liquid crystal alignment agents of Examples 26-29 contained a polymer (third polymer) that lacked structural units (U1) and (U2-2), and was more likely to be concentrated on the substrate interface side than polymer (P) and polymer (Q-1). All of these exhibited "excellent" or "good" DC accumulation characteristics and demonstrated a superior balance of various properties. It is presumed that the inclusion of this third polymer suppressed charge transfer (hole injection, etc.) with the ITO electrode, further reducing charge accumulation. Generally, hole-transporting diamines have a high HOMO (highest occupied orbital) energy level, and it is thought that hole injection from the ITO electrode is more likely to occur when this level exceeds the work function of ITO.

[0158] [Examples 30-40] In Example 1 described above, a liquid crystal alignment agent was prepared in the same manner as in Example 1, except that the types and amounts of polymer components and crosslinking agents contained in the liquid crystal alignment agent were changed as shown in Table 6 below. A liquid crystal alignment film was formed by photo-alignment, and an FFS-type liquid crystal display element was manufactured and various evaluations were performed. The evaluation results are shown in Table 6 below.

[0159] [Table 6]

[0160] In Table 6, the mass ratio of each polymer in the liquid crystal alignment agent indicates the proportion (in parts by mass) of each polymer relative to 100 parts by mass of the total polymer components used in the preparation of the liquid crystal alignment agent. For each example of the liquid crystal alignment agent, an adhesion aid (3-glycidyloxypropyltrimethoxysilane (the compound represented by the above formula (AD-4))) was added in an amount of 1 part by mass per 100 parts by mass of the total polymer components.

[0161] As shown in Table 6, the liquid crystal alignment agents of Examples 30-40 containing polymer (P) exhibited "good" liquid crystal alignment properties for liquid crystal display elements, and both DC relaxation and DC storage characteristics were "excellent" or "good," demonstrating a good balance of various properties.

[0162] From the above, it has become clear that liquid crystal alignment agents containing polymer (P) have good liquid crystal alignment properties for liquid crystal display elements, as well as good DC accumulation and DC relaxation characteristics, and are less prone to afterimages.

Claims

1. Polymer (P) and, A polymer (Q) different from the aforementioned polymer (P), It contains, The polymer (P) contains within the same molecule a substructure represented by formula (1) below, and one or more substructures represented by formula (2), formula (3), and formula (4) below, and a molecule containing the substructure represented by formula (1) below contains two or more substructures represented by formula (2), formula (3), and formula (4) below within the same molecule or in different molecules. The polymer (Q) is at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide, and does not have a substructure represented by the following formula (1), and is a liquid crystal alignment agent. 【Chemistry 1】 (In formula (1), X １ Y is a tetravalent organic group. １ This is a divalent organic group having a substructure obtained by removing two hydrogen atoms from the structure represented by the following formula (Y-1). 【Chemistry 2】 In formula (Y-1), A １ and A ２ are each independently a monovalent group having an aromatic hydrocarbon ring, wherein the aromatic hydrocarbon ring is bonded to the nitrogen atom in formula (Y-1), or A １ and A ２ are combined with each other to represent a nitrogen-containing fused heterocyclic ring structure constituted together with the nitrogen atom to which A １ and A ２ are bonded. A ３ is a hydrogen atom or a monovalent organic group. Provided that when A １ and A ２ are combined with each other to represent a nitrogen-containing fused heterocyclic ring structure constituted together with the nitrogen atom to which A １ and A ２ are bonded, the nitrogen-containing fused heterocyclic ring structure has two or more aromatic hydrocarbon rings, and the nitrogen-containing fused heterocyclic ring structure has a fused ring structure in which two aromatic hydrocarbon rings thereof are bonded sharing the nitrogen atom in formula (Y-1), or A ３ has an aromatic hydrocarbon ring, and the aromatic hydrocarbon ring of A ３ is bonded to the nitrogen atom in formula (Y-1).) 【Transformation 3】 (In equations (2), (3), and (4), X ２ , X ３ and X ４ These are each independently tetravalent organic groups. ２ The chain-like hydrocarbon structure and "* １ -NR １ -CO-", * １ -CO-NR １ -", * １ -NR １ -CO-NR ２ -" or "* １ -CO-NR １ -NR ２ It is a divalent group that contains a substructure adjacent to "-CO-" in the main chain. １ and R ２ Each of these is independently a hydrogen atom or a monovalent organic group. １ " represents a bond with a chain-like hydrocarbon structure. Y ３ This is a divalent organic group having a carboxylic acid group or a sulfonic acid group. ４ This is a nitrogen-containing heterocycle, "-R ３ -NR ４ -R ５ -" and -R ６ -NR ７ R ８ A divalent organic group having a nitrogen-containing structure Ny, which is at least one substructure selected from the group consisting of the following (where Y ２ Excluding the group corresponding to the above.) and having the nitrogen-containing structure Ny in the side chain. R ３ , R ５ and R ６ These are each independently divalent aliphatic hydrocarbon groups. ４ , R ７ and R ８ Each of these is independently a hydrogen atom, a thermally leaving group, or a monovalent aliphatic hydrocarbon group.

2. The liquid crystal alignment agent according to claim 1, wherein the polymer (P) contains within the same molecule a substructure represented by formula (1), and two or more substructures represented by formula (2), formula (3), and formula (4).

3. The liquid crystal alignment agent according to claim 1, wherein the polymer (P) comprises structural units derived from aromatic tetracarboxylic dianhydride.

4. The liquid crystal alignment agent according to claim 1, wherein the polymer (Q) contains a polymer selected from the group consisting of a substructure represented by the following formula (5) and a substructure represented by the following formula (6). 【Chemistry 4】 (In equations (5) and (6), X ５ and X ６ These are, independently, tetravalent groups having an alicyclic structure. ５ and Y ６ These are divalent organic groups, each independently containing a substructure in which a thermally leaveable group is bonded to a nitrogen atom.

5. The liquid crystal alignment agent according to claim 4, wherein the alicyclic structure is a substituted or unsubstituted cyclobutane ring structure.

6. The liquid crystal alignment agent according to claim 1, further comprising a compound having three or more of at least one selected from the group consisting of an oxiranyl group, an oxetanyl group, a hydroxyl group, a mercapto group, an amino group, and a polymerizable carbon-carbon double bond group in one molecule.

7. The liquid crystal alignment agent according to claim 1, further comprising a compound having a trialkoxysilyl group.

8. A liquid crystal alignment film formed using the liquid crystal alignment agent described in any one of claims 1 to 7.

9. A liquid crystal element comprising the liquid crystal alignment film described in claim 8.

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