Liquid crystal alignment agent, liquid crystal alignment film, manufacturing method of the same, and liquid crystal element

Abstract

To provide a liquid crystal alignment agent capable of forming a liquid crystal alignment film excellent in dynamic characteristics while a liquid crystal element has excellent liquid crystal alignment characteristics, voltage holding characteristics and an AC afterimage characteristics.SOLUTION: Liquid crystal alignment agent contains polymer (P) including a partial structure represented by formula (1) in a main chain. Ar1 and Ar2 represent a divalent aromatic ring group. At least one of Ar1 and Ar2 includes an aromatic heterocyclic group having at least one type selected from the group consisting of nitrogen, oxygen and sulphur, and a monovalent substituent group directly coupling to the aromatic heterocyclic group. Z1 and Z2 represent a single bond, -NR2-, -O-, -S-, -CO-, *1-NR2-CO-, *1-CO-NR2-, *1-NR2-CO-NR3-, *1-CO-O- or *1-O-CO-. B1 and B2 represent a single bond or divalent linear hydrocarbon group with 1-8 carbons. The number of atoms for a group coupling Ar1 and Ar2 in the formula (1) composing the main chain of the polymer is 0 to 8.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a liquid crystal aligning agent, a liquid crystal alignment film and a method for producing the same, and a liquid crystal device. [Background technology]

[0002] A liquid crystal element has a liquid crystal alignment film that functions to align liquid crystal molecules in a liquid crystal layer in a specific direction. A liquid crystal alignment film is generally formed on a substrate by applying a liquid crystal alignment agent, which is a polymer component dissolved in a solvent, to the substrate surface, and preferably by heating.

[0003] In recent years, with the advancement of higher resolution and versatility in liquid crystal elements, the quality requirements for liquid crystal elements have become even stricter. For example, liquid crystal elements are required not only to have improved liquid crystal alignment and voltage holding ratio, but also to withstand physical pressure such as transportation and tapping, and to be less susceptible to bright spot defects even when negative liquid crystals are used (see, for example, Patent Documents 1 and 2). It is believed that the use of negative liquid crystals can improve the contrast of liquid crystal elements.

[0004] Patent Document 1 discloses that a liquid crystal alignment film is formed using a liquid crystal aligning agent containing at least one polymer selected from the group consisting of polyimide precursors and imidized polymers of the polyimide precursors, and a crosslinking agent having a hydroxyamide group and an acid anhydride structure, thereby improving the mechanical strength of the liquid crystal alignment film without reducing the liquid crystal alignment properties.

[0005] Furthermore, Patent Document 2 discloses that by forming a liquid crystal alignment film using a polymer having a specific asymmetric partial structure in the main chain, even when a negative liquid crystal is used, bright spots resulting from decomposition products of the polymer constituting the liquid crystal alignment film caused by irradiation with polarized ultraviolet light do not occur, resulting in a liquid crystal element that exhibits good afterimage characteristics. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2020 / 171128 [Patent Document 2] International Publication No. 2016 / 152928 Summary of the Invention [Problem to be solved by the invention]

[0007] Increasing the amount of crosslinking agent added to further increase resistance to physical pressures such as vibrations and tapping during transportation tends to lead to a decrease in the liquid crystal alignment of the resulting liquid crystal element. Furthermore, when a polymer having a specific asymmetric partial structure in the main chain is used as in Patent Document 2, there is a concern that decomposition products of the polymer generated by irradiation with polarized ultraviolet light will dissolve excessively in the liquid crystal layer, causing a decrease in the voltage holding ratio of the liquid crystal element.

[0008] Furthermore, liquid crystal elements with liquid crystal alignment films with good mechanical properties are prone to image retention due to the application of alternating current voltage (hereinafter also referred to as "AC image retention"). Therefore, there is often a trade-off between the mechanical properties of the film and the AC image retention characteristics of the liquid crystal element. AC image retention is an image retention that occurs when the initial alignment direction of a liquid crystal element deviates from the direction at the time of manufacturing the liquid crystal element due to long-term operation of the liquid crystal element. In particular, photo-alignment methods tend to be more prone to AC image retention because the alignment control force of liquid crystal molecules is insufficient compared to rubbing methods. To meet the recent demand for even higher performance, liquid crystal alignment agents are required to have good mechanical properties for the liquid crystal alignment film, as well as good liquid crystal alignment, voltage retention, and AC image retention characteristics.

[0009] The present invention has been made in consideration of the above-mentioned problems, and one object of the present invention is to provide a liquid crystal alignment agent that can form a liquid crystal alignment film having excellent mechanical properties while providing good liquid crystal alignment properties, voltage retention characteristics, and AC afterimage characteristics of a liquid crystal element. [Means for solving the problem]

[0010] According to the present invention, there are provided the following liquid crystal aligning agent, liquid crystal alignment film and method for producing the same, and liquid crystal device. [1] A liquid crystal aligning agent containing a polymer (P) having a partial structure represented by the following formula (1) in its main chain: [ka] (In formula (1), Ar 1 and Ar 2 are each independently a divalent aromatic ring group, provided that Ar 1 and Ar 2 At least one of Z has an aromatic heterocycle having at least one element selected from the group consisting of nitrogen, oxygen, and sulfur, and a monovalent substituent directly bonded to the aromatic heterocycle. 1 and Z 2 are, independently of each other, a single bond, -NR 2 -, -O-, -S-, -CO-, * 1 -NR 2 -CO-, * 1 -CO-NR 2 -, * 1 -NR 2 -CO-NR 3 -, * 1 -CO-O- or * 1 -O-CO-. R 2 and R 3 are each independently a hydrogen atom or a monovalent organic group. 1 " is Ar 1 or Ar 2 It represents a bond with L. 1 is -NR 4 -, -O-, -S-, -CO-, * 2 -NR 4 -CO-, * 2 -CO-NR 4 -, -NR 4 -CO-NR 5 -, * 2 -CO-O- or * 2 -O-CO-. R 4 and R 5 are each independently a hydrogen atom or a monovalent organic group. 2 " is B 1 B1 and B 2 are each independently a single bond or a divalent chain hydrocarbon group having 1 to 8 carbon atoms, and n is 0 or 1. However, Ar 1 and Ar 2 The number of atoms constituting the main chain of the polymer in the group connecting

[0011] [2] A liquid crystal alignment film formed using the liquid crystal alignment agent according to [1] above. [3] A method for producing a liquid crystal alignment film, comprising the steps of forming a coating film using the liquid crystal aligning agent according to [1] above, and subjecting the coating film to a light irradiation treatment to impart liquid crystal aligning ability. [4] A liquid crystal element comprising the liquid crystal alignment film of [2] above. [Effects of the Invention]

[0012] According to the liquid crystal aligning agent of the present invention, it is possible to form a liquid crystal alignment film having excellent mechanical properties while providing a liquid crystal element with good liquid crystal alignment properties, voltage retention characteristics, and AC afterimage characteristics. DETAILED DESCRIPTION OF THE INVENTION

[0013] Matters relating to aspects of the present disclosure will be described in detail below.

[0014] Here, in this specification, a numerical range indicated using "to" means that the numerical values ​​before and after "to" are included as the lower and upper limits. A "structural unit" refers to a unit that mainly constitutes the main chain structure, and at least two or more units are contained in the main chain structure. A structural unit is typically a repeating unit constituted based on one monomer. Note that a structural unit may be obtained by reacting a repeating unit having a reactive group with a compound having a functional group that can react with the reactive group.

[0015] As used herein, the term "hydrocarbon group" includes chain hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. The term "chain hydrocarbon group" refers to a linear hydrocarbon group or a branched hydrocarbon group that does not contain a cyclic structure and is composed solely of a chain structure. However, the group may be saturated or unsaturated. The term "alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic hydrocarbon structure as a ring structure and does not contain an aromatic ring structure. However, the group does not necessarily have to be composed solely of an alicyclic hydrocarbon structure, and may also contain a chain structure as part of the ring structure. The term "aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as a ring structure. However, the group does not necessarily have to be composed solely of an aromatic ring structure, and may contain a chain structure or an alicyclic hydrocarbon structure as part of the ring structure. The term "organic group" refers to an atomic group obtained by removing any hydrogen atom from a carbon-containing compound (i.e., an organic compound).

[0016] The "main chain" of a polymer refers to the "trunk" portion of the polymer, which is the longest chain of atoms. It is permissible for this "trunk" portion to contain a ring structure. For example, "having a specific structure in the main chain" means that the specific structure constitutes a part of the main chain. A "side chain" refers to a portion branched from the "trunk" portion of the polymer.

[0017] <Liquid crystal alignment agent> The liquid crystal aligning agent of the present disclosure will be described below. The liquid crystal aligning agent of the present disclosure contains a polymer (P) having a partial structure represented by the following formula (1) in the main chain. [ka] (In formula (1), Ar 1 and Ar 2 are each independently a divalent aromatic ring group, provided that Ar 1 and Ar 2 At least one of Z has an aromatic heterocycle having at least one element selected from the group consisting of nitrogen, oxygen, and sulfur, and a monovalent substituent directly bonded to the aromatic heterocycle. 1 and Z 2 are, independently of each other, a single bond, -NR 2 -, -O-, -S-, -CO-, * 1-NR 2 -CO-, * 1 -CO-NR 2 -, * 1 -NR 2 -CO-NR 3 -, * 1 -CO-O- or * 1 -O-CO-. R 2 and R 3 are each independently a hydrogen atom or a monovalent organic group. 1 " is Ar 1 or Ar 2 It represents a bond with L. 1 is -NR 4 -, -O-, -S-, -CO-, * 2 -NR 4 -CO-, * 2 -CO-NR 4 -, -NR 4 -CO-NR 5 -, * 2 -CO-O- or * 2 -O-CO-. R 4 and R 5 are each independently a hydrogen atom or a monovalent organic group. 2 " is B 1 B 1 and B 2 are each independently a single bond or a divalent chain hydrocarbon group having 1 to 8 carbon atoms, and n is 0 or 1. However, Ar 1 and Ar 2 The number of atoms constituting the main chain of the polymer in the group connecting

[0018] <Polymer (P)> The polymer (P) may have a partial structure represented by the above formula (1) (hereinafter also referred to as the "specific partial structure") in its main chain, and its main skeleton is not particularly limited. From the viewpoints of ease of incorporation of the specific partial structure into the polymer main chain, affinity with liquid crystals, and mechanical strength, the polymer (P) is preferably a condensation polymer obtained using a diamine compound as a monomer. Examples of such condensation polymers include polymers having a polyamic acid, polyamic acid ester, polyimide, polyamine, polyenamine, polyamide, polyamideimide, polyurea, or polyimine as the main skeleton. The polyenamine is a polymer having a carbon-carbon double bond adjacent to the amino group of the polyamine, and examples thereof include polyenaminoketone, polyenaminoester, polyenaminonitrile, and polyenaminosulfonyl.

[0019] In terms of obtaining a liquid crystal element with excellent liquid crystal alignment properties and voltage retention characteristics, the polymer (P) is preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, polyamide, polyamideimide, polyurea, and polyimine, and more preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide.

[0020] ·Specific partial structure In the above formula (1), Ar 1 or Ar 2 The divalent aromatic ring group represented by the formula (I) is a group obtained by removing two hydrogen atoms from the ring portion of a substituted or unsubstituted aromatic ring. The aromatic ring may be an aromatic hydrocarbon ring or an aromatic heterocycle. Specific examples of the aromatic hydrocarbon ring include a benzene ring, a biphenyl ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring. The aromatic heterocycle preferably contains at least one selected from the group consisting of nitrogen, oxygen, and sulfur, and examples thereof include nitrogen-containing aromatic heterocycles such as a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring, a quinoline ring, an isoquinoline ring, an acridine ring, and a carbazole ring; oxygen-containing aromatic heterocycles such as a furan ring; and sulfur-containing aromatic heterocycles such as a thiophene ring. Ar 1 or Ar2 When is an aromatic heterocyclic group, the aromatic heterocyclic group is preferably a nitrogen-containing heterocyclic group, and more preferably a pyridine ring, a pyrimidine ring, or a pyrazine ring, in that a liquid crystal device having excellent AC image retention characteristics and voltage retention characteristics can be obtained.

[0021] Ar 1 and Ar 2 At least one of the groups has an aromatic heterocycle having at least one element selected from the group consisting of nitrogen, oxygen, and sulfur, and a monovalent substituent directly bonded to the aromatic heterocycle. a "), it is preferable that an atom directly bonded to the aromatic heterocycle has an unshared electron pair, or that one or more hydrogen atoms are bonded to an atom directly bonded to the aromatic heterocycle, in order to obtain a liquid crystal alignment film having excellent mechanical properties.

[0022] Substituent R a Preferred specific examples of the alkyl group include an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, a hydroxy group, an alkoxy group having 1 to 5 carbon atoms, a thioalkoxy group having 1 to 5 carbon atoms, a hydroxyalkyl group having 1 to 5 carbon atoms, an alkoxyalkyl group having 1 to 5 carbon atoms, 3 -NR 6 R 7 , * 3 -OC(=O)-R 7 , * 3 -NR 6 -C(=O)-R 7 , and * 3 -NR 6 -C(=O)-NR 7 R 8 (However, R 6 , R 7 and R 8 are each independently a hydrogen atom or a monovalent organic group. 3 " represents a bond to the aromatic heterocycle.)

[0023] where R 6 , R 7 or R8 Examples of the monovalent organic group represented by the formula (I) include a monovalent chain hydrocarbon group having 1 to 5 carbon atoms and a thermally cleavable group. Examples of the monovalent chain hydrocarbon group having 1 to 5 carbon atoms include an alkyl group and an alkenyl group. Of these, an alkyl group having 1 to 5 carbon atoms is preferred, and an alkyl group having 1 to 3 carbon atoms is more preferred.

[0024] Examples of thermally detachable groups include carbamate-based detachable groups, amide-based detachable groups, imide-based detachable groups, and sulfonamide-based detachable groups. Among these, carbamate-based detachable groups are preferred because of their high thermal detachability. Specific examples of carbamate-based detachable groups include an isopropyloxycarbonyl group, a tert-butoxycarbonyl group (Boc group), a 2-methyl-2-butyloxycarbonyl group, a benzyloxycarbonyl group, a 1,1-dimethyl-2-haloethyloxycarbonyl group, an allyloxycarbonyl group, a 2-(trimethylsilyl)ethoxycarbonyl group, and a 9-fluorenylmethyloxycarbonyl group (F-moc group). Among these, a branched alkyloxycarbonyl group having 3 to 6 carbon atoms is more preferred, and a tert-butoxycarbonyl group (Boc group) is particularly preferred, because they are easily removed by heat and can reduce the amount of deprotected portions remaining in the film.

[0025] R 6 , R 7 and R 8 From the viewpoint of improving the mechanical properties of the liquid crystal alignment film, each of the above is preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a thermally cleavable group, more preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or an alkyloxycarbonyl group having a branched alkyl group having 3 to 6 carbon atoms, and even more preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a Boc group.

[0026] Substituent R for aromatic heterocycle a The bonding position of the substituent R is not particularly limited. a For aromatic heterocycles, Z 1 or Z 2It is preferable that the substituent R is bonded to a position adjacent to the bonding position of the substituent R (this is referred to as the "first position") or to a position adjacent to the first position (this is referred to as the "second position"). For example, when the aromatic heterocycle is a 6-membered ring, the substituent R a is Z 1 or Z 2 It is preferable that the substituent R is bonded to an ortho position (corresponding to the first position) or meta position (corresponding to the second position) relative to the bonding position of the aromatic heterocycle. a There is no particular limitation on the number of substituents R a The number of is preferably 1 to 4, more preferably 1 or 2, and even more preferably 1 per aromatic heterocycle.

[0027] Ar 1 or Ar 2 When the aromatic ring group represented by the formula (I) is an aromatic hydrocarbon ring group, the aromatic hydrocarbon ring group may have a substituent on the ring portion. Examples of the substituent include the substituent R a Preferred specific examples of the group include the same groups as those exemplified above.

[0028] Ar 1 and Ar 2 At least one of these may be an aromatic heterocyclic group. 1 and Ar 2 may be the same group or different groups. 1 and Ar 2 are the same group, Ar 1 and Ar 2 The types of aromatic rings possessed by Ar and Ar , and the types, numbers and bonding positions of the substituents bonded to the aromatic rings are also the same. 1 and Ar 2 The aromatic rings that make up each group may be different, or Ar 1 and Ar 2 The types of aromatic rings constituting each of Ar and Ar are the same, but at least one of the types, numbers, and bonding positions of the substituents bonded to the aromatic rings is different. 1 and Ar 2 This corresponds to the case where Ar is a different group.1 and Ar 2 When the groups are different from each other, it is preferable in that the occurrence of display defects (bright spots) caused by decomposition products of the liquid crystal alignment film can be further reduced.

[0029] Ar is preferred because it can more effectively reduce the occurrence of bright spots. 1 and Ar 2 The aromatic rings constituting each of Ar are preferably different in type. 1 and Ar 2 It is more preferable that one of Ar is an aromatic heterocyclic group and the other is an aromatic hydrocarbon group. 1 and Ar 2 It is preferred that one of the groups is a substituted pyridinediyl group, a substituted pyrimidinediyl group, or a substituted pyrazinediyl group, and the other is a phenylene group, a biphenylene group, or a naphthalene group.

[0030] Z 1 and Z 2 are, independently of each other, a single bond, -NR 2 -, -O-, -S-, -CO-, * 1 -NR 2 -CO-, * 1 -CO-NR 2 -, * 1 -NR 2 -CO-NR 3 -, * 1 -CO-O- or * 1 -O-CO-, where R 2 or R 3 Specific and preferred examples of the monovalent organic group represented by R 6 , R 7 or R 8 In order to improve the mechanical properties of the liquid crystal alignment film, the specific examples and preferred examples of the monovalent organic group represented by R 2 and R 3 are each preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or a thermally detachable group, more preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or a Boc group.

[0031] Z1 and Z 2 may be the same group or different groups. 1 and Z 2 When Z and Z are different groups, it is preferable in that the occurrence of display defects (bright spots) caused by decomposition products of the liquid crystal alignment film can be further reduced. 1 and Z 2 At least one of them is Ar 1 or Ar 2 It is sufficient that the compound is bonded to the aromatic heterocycle in the compound. 1 and Ar 2 one of which is an aromatic heterocyclic group and the other is an aromatic hydrocarbon group, and Z 1 and Z 2 and are preferably different groups.

[0032] Z is advantageous in that it can provide a liquid crystal alignment film with excellent mechanical properties. 1 and Z 2 In the case of Z, it is preferred that an atom directly bonded to the aromatic heterocycle has an unshared electron pair, or that one or more hydrogen atoms are bonded to an atom directly bonded to the aromatic heterocycle. 1 and Z 2 The group bonded to the aromatic heterocycle is -NR 2 -, -O-, -S-, * 1 -NR 2 -CO-, * 1 -CO-NR 2 -, * 1 -NR 2 -CO-NR 3 -, * 1 -CO-O- or * 1 -O-CO- is preferred.

[0033] In order to obtain a liquid crystal alignment film having excellent mechanical properties while maintaining good liquid crystal alignment properties and voltage retention characteristics of the liquid crystal element, it is preferable that the specific partial structure satisfy both of the following conditions 1 and 2. (Condition 1) Substituent R a Among the atoms constituting the aromatic heterocycle, an atom directly bonded to the aromatic heterocycle has an unshared electron pair, or the substituent Ra Among the atoms that make up the heteroaromatic ring, one or more hydrogen atoms are bonded to the atoms that are directly bonded to the aromatic heterocycle. (Condition 2) An atom in the main chain directly bonded to the aromatic heterocycle has an unshared electron pair, or the structure includes one or more hydrogen atoms bonded to an atom in the main chain directly bonded to the aromatic heterocycle.

[0034] The specific partial structure is, in particular, a substituent R a is an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, a hydroxy group, an alkoxy group having 1 to 5 carbon atoms, a thioalkoxy group having 1 to 5 carbon atoms, a hydroxyalkyl group having 1 to 5 carbon atoms, an alkoxyalkyl group having 1 to 5 carbon atoms, * 3 -NR 6 R 7 , * 3 -OC(=O)-R 7 , * 3 -NR 6 -C(=O)-R 7 , and * 3 -NR 6 -C(=O)-NR 7 R 8 and, with respect to the aromatic heterocycle, -CH2-, -NR 2 -, -O-, -S-, * 1 -NR 2 -CO-, * 1 -CO-NR 2 -, * 1 -NR 2 -CO-NR 3 -, * 1 -CO-O- or * 1 The bond is preferably -O-CO-.

[0035] L 1 is -NR 4 -, -O-, -S-, -CO-, * 2 -NR 4 -CO-, * 2 -CO-NR 4 -, -NR 4 -CO-NR 5 -, * 2 -CO-O- or *2 -O-CO-. R 4 or R 5 Specific and preferred examples of the monovalent organic group represented by R 6 , R 7 or R 8 In order to improve the mechanical properties of the liquid crystal alignment film, the specific examples and preferred examples of the monovalent organic group represented by R 4 and R 5 are each preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or a thermally detachable group, more preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or a Boc group.

[0036] B 1 or B 2 The divalent chain hydrocarbon group having 1 to 8 carbon atoms represented by the formula (I) may be saturated or unsaturated, and may be linear or branched. From the viewpoint of improving the liquid crystal alignment property of the liquid crystal element and the mechanical properties of the liquid crystal alignment film, B 1 or B 2 Of these, the divalent chain hydrocarbon group having 1 to 8 carbon atoms represented by the formula (I) is preferably a saturated chain hydrocarbon group (alkanediyl group), more preferably a linear alkanediyl group. In addition, from the viewpoint of improving the liquid crystal alignment property and AC image retention characteristics of the liquid crystal element in a well-balanced manner, 1 or B 2 The divalent chain hydrocarbon group having 1 to 8 carbon atoms represented by the following formula (I) preferably has 2 to 6 carbon atoms, and more preferably has 2 to 4 carbon atoms.

[0037] In the above formula (1), Ar 1 and Ar 2 and a group linking them (i.e., the following formula (LA): [ka] The number of atoms constituting the main chain of the polymer in which the group represented by the formula (a) is 0 to 8 is. That is, "the number of atoms constituting the main chain of the polymer" refers to the number of atoms in which adjacent atoms are bonded (preferably bonded by a single bond) and arranged in a straight line. For example, Z 1 Ga-NR 2 -, n is 0, and B 2is an ethylene group, and Z 2 Ga-NR 2 -, if Ar 1 and Ar 2 The number of atoms that make up the main chain of the polymer is four (-NCCN-). 1 is -O-, n is 1, and B 1 is a methylene group, and L 1 Ga-NR 4 -CO-NR 5 - and B 2 is a methylene group, and Z 2 When is -O-, Ar 1 and Ar 2 The number of atoms constituting the main chain of the polymer in the group connecting the above formula (LA) is 7 (-OCNCNCO-). When the number of atoms constituting the main chain of the polymer in the group represented by the above formula (LA) is 0, Ar 1 and Ar 2 means that it is bonded by a single bond. 1 and Ar 2 When the group connecting Ar and Ar is -O-CH2-CH2-NH-CO-NH-CH2-CH2-O-, 1 and Ar 2 The number of atoms constituting the main chain of the polymer in the group connecting

[0038] The Ar 1 and Ar 2 The number of atoms constituting the main chain of the polymer in the group linking Ar is preferably 2 or more, more preferably 4 or more. 1 and Ar 2 The number of atoms constituting the main chain of the polymer in the group linking Ar and Ar is 8 or less, and preferably 7 or less. 1 and Ar 2 The group linking these preferably contains an alkanediyl group having 1 to 6 carbon atoms.

[0039] The proportion of the specific partial structure in polymer (P) is preferably 1 mol % or more, more preferably 5 mol % or more, and even more preferably 10 mol % or more, based on the total amount of structural units (i.e., monomer units) contained in polymer (P). The proportion of the specific partial structure is, for example, 50 mol % or less, based on the total amount of structural units contained in polymer (P).

[0040] In view of the ease of introducing the specific partial structure into the polymer main chain and the ability to form a liquid crystal alignment film excellent in affinity with liquid crystals and mechanical strength, it is preferable that the polymer (P) contains a structural unit derived from a diamine having the specific partial structure (hereinafter also referred to as a "specific diamine"). A preferred example of the specific diamine is a compound represented by the following formula (2). [ka] (In formula (2), Ar 1 , Ar 2 , Z 1 , Z 2 , L 1 , B 1 , B 2 and n have the same meanings as in formula (1) above.

[0041] Specific examples of the specific diamine include compounds represented by the following formulas. [ka] [ka] [ka] [ka] [ka] [ka] [ka]

[0042] Synthesis of polymer (P) The synthesis method of the polymer (P) is not particularly limited and can be appropriately selected depending on the type of main skeleton. For example, when the polymer (P) is a polyamic acid, a polyamic acid ester, or a polyimide, an example of the synthesis method of the polymer (P) is a method including a step of condensation polymerization of a tetracarboxylic acid derivative with a diamine compound containing a specific diamine. The tetracarboxylic acid derivative includes a tetracarboxylic acid dianhydride, a tetracarboxylic acid dihalide, and a tetracarboxylic acid diester dihalide. The polyamic acid, the polyamic acid ester, and the polyimide are each described in detail below.

[0043] (Polyamic acid) When the polymer (P) is a polyamic acid, the polyamic acid (hereinafter also referred to as "polyamic acid (P)") can be obtained by reacting (polycondensation reaction) a tetracarboxylic dianhydride with a diamine compound.

[0044] Examples of the tetracarboxylic acid dianhydride used in the synthesis of the polyamic acid (P) include aliphatic tetracarboxylic acid dianhydrides and aromatic tetracarboxylic acid dianhydrides. Examples of the aliphatic tetracarboxylic acid dianhydrides include linear tetracarboxylic acid dianhydrides and alicyclic tetracarboxylic acid dianhydrides.

[0045] Examples of the tetracarboxylic dianhydride include chain tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride and ethylenediaminetetraacetic dianhydride; Examples of alicyclic tetracarboxylic dianhydrides include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 5-(2,5-dioxotetrahydrofuran-3-yl)-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 5-(2,5-dioxotetrahydrofuran-3-yl)-8-methyl-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 3-oxabicyclo[3 .2.1]octane-2,4-dione-6-spiro-3'-(tetrahydrofuran-2',5'-dione), 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2:3,5:6-dianhydride, bicyclo[3.3.0]octane-2,4,6,8-tetracarboxylic acid 2:4,6:8-dianhydride, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic acid 2:3,5:6-dianhydride, 4,9-dioxatricyclo[5.3.1.0]octane-2,4,6,8-tetracarboxylic acid 2:4,6:8-dianhydride 2,6 ]undecane-3,5,8,10-tetraone, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, etc.; Examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, p-phenylene bis(trimellitic acid monoester anhydride), ethylene glycol bis(anhydrotrimellitate), 1,3-propylene glycol bis(anhydrotrimellitate), 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 4,4'-biphthalic dianhydride, 4,4'-oxydiphthalic dianhydride, and 4,4'-carbonyldiphthalic anhydride; and the tetracarboxylic dianhydrides described in JP-A-2010-97188 can also be used.

[0046] The tetracarboxylic acid dianhydride preferably includes an aliphatic tetracarboxylic acid dianhydride, more preferably an alicyclic tetracarboxylic acid dianhydride, in terms of increasing the solubility of the polymer (P) and enabling the formation of a liquid crystal alignment film exhibiting good liquid crystal alignment properties. Specifically, the tetracarboxylic acid dianhydride preferably includes at least one selected from the group consisting of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 2,4,6,8-tetracarboxybicyclo[3.3.0]octane-2:4,6:8-dianhydride, cyclopentanetetracarboxylic acid dianhydride, and cyclohexanetetracarboxylic acid dianhydride.

[0047] In the polyamic acid (P), the content of structural units derived from an alicyclic tetracarboxylic dianhydride is preferably 20 mol % or more, more preferably 30 mol % or more, even more preferably 50 mol % or more, and particularly preferably 70 mol % or more, based on the total amount of structural units derived from tetracarboxylic dianhydride contained in the polyamic acid (P).

[0048] Furthermore, when a polymer film formed using a liquid crystal aligning agent is provided with liquid crystal aligning ability by a photoalignment method, the polymer (P) preferably contains structural units derived from 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride. In the polymer (P), the proportion of structural units derived from 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more, based on the total amount of structural units derived from tetracarboxylic dianhydride contained in the polymer (P).

[0049] When synthesizing the polyamic acid (P), only the specific diamine may be used as the diamine compound. Alternatively, a diamine different from the specific diamine (hereinafter also referred to as "other diamine") may be used together with the specific diamine. Examples of other diamines include aliphatic diamines, aromatic diamines, and diaminoorganosiloxanes. Examples of aliphatic diamines include linear diamines and alicyclic diamines.

[0050] Specific examples of other diamines include chain diamines such as metaxylylenediamine and hexamethylenediamine; and alicyclic diamines such as 1,4-diaminocyclohexane and 4,4'-methylenebis(cyclohexylamine).

[0051] Examples of aromatic diamines include p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenyl ether, 4-aminophenyl-4-aminobenzoate, 4,4'-diaminoazobenzene, 3,5-diaminobenzoic acid, 1,5-bis(4-aminophenoxy)pentane, 1,2-bis(4-aminophenoxy)ethane, 1,3-bis(4-aminophenoxy)ethane ... 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis(4-aminophenyl)hexafluorooctanoic acid, 1,6-bis(4-aminophenoxy)hexane, bis[2-(4-aminophenyl)ethyl]hexanedioic acid, 1,4-bis-(4-aminophenyl)-piperazine, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis(4-aminophenyl)hexafluorooctanoic acid Fluoropropane, 4,4'-(phenylenediisopropylidene)bisaniline, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-[4,4'-propane-1,3-diylbis(piperidine-1,4-diyl)]dianiline, 4,4'-diaminobenzanilide, 4,4'-diaminostilbene, 1,4-bis(4-aminophenyl)-piperazine, 4,4' -diaminodiphenethyl urea, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, N,N'-di(4-amino-2-pyridyl)-N,N'-di(tert-butoxycarbonyl)ethylenediamine, N,N'-bis[2-(4-aminophenyl)ethyl]hexanediamide, N,N'-bis[2-(4-aminophenyl)ethyl]-N,N'-di(tert-butoxycarbonyl)hexanediamide, [ka] [ka] Main chain diamines such as; Dodecanoxy-2,4-diaminobenzene, pentadecanoxy-2,4-diaminobenzene, hexadecanoxy-2,4-diaminobenzene, octadecanoxy-2,4-diaminobenzene, pentadecanoxy-2,5-diaminobenzene, octadecanoxy-2,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, 3,5-di Cholestanyl aminobenzoate, cholestenyl 3,5-diaminobenzoate, lanostaniyl 3,5-diaminobenzoate, 3,6-bis(4-aminobenzoyloxy)cholestane, 3,6-bis(4-aminophenoxy)cholestane, 4-(4'-trifluoromethoxybenzoyloxy)cyclohexyl-3,5-diaminobenzoate, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-butylcyclohexane, 5ξ-cholestan-3-yl 3,5-diaminobenzoate, the following formula (E-1): [ka] (In formula (E-1), X I and X II are each independently a single bond, -O-, *-COO-, or *-OCO- (where * indicates the bond to the diaminophenyl group). I is an alkanediyl group having 1 to 3 carbon atoms. II R is a single bond or an alkanediyl group having 1 to 3 carbon atoms. III 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 of 0 to 3. c is an integer of 0 to 2. d is 0 or 1, provided that 1≦a+b+c≦3. and side chain diamines such as compounds represented by the following formula:

[0052] Examples of the compound represented by formula (E-1) include compounds represented by the following formulas (E-1-1) to (E-1-4). [ka]

[0053] Specific examples of diaminoorganosiloxanes include 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, etc. In addition to the above, other diamines that can be used include the diamines described in JP-A-2010-97188.

[0054] The proportion of the structural units derived from the specific diamine in the polymer (P) is preferably 2 mol % or more, more preferably 10 mol % or more, and even more preferably 20 mol % or more, based on the total amount of structural units derived from the diamine compounds contained in the polymer (P). By setting the proportion of the structural units derived from the specific diamine in the above range, the mechanical properties of the film and the liquid crystal alignment, voltage retention characteristics, and AC image retention characteristics of the liquid crystal element can be improved.

[0055] When polymer (P) contains structural units derived from other diamines, the proportion of the other structural units in polymer (P) is preferably 5 mol % or more, more preferably 10 mol % or more, and even more preferably 15 mol % or more, based on the total amount of structural units derived from diamine compounds contained in polymer (P). The proportion of the structural units derived from other diamines is preferably 98 mol % or less, more preferably 90 mol % or less, and even more preferably 80 mol % or less, based on the total amount of structural units derived from diamine compounds contained in polymer (P).

[0056] Synthesis of polyamic acid (P) The polyamic acid (P) can be obtained by reacting a tetracarboxylic dianhydride with a diamine compound, optionally together with a molecular weight modifier. The ratio of the tetracarboxylic dianhydride and the diamine compound used in the synthesis reaction of the polyamic acid (P) is preferably such that 0.2 to 2 equivalents of the acid anhydride group of the tetracarboxylic dianhydride are used per equivalent of the amino group of the diamine compound.

[0057] Examples of molecular weight modifiers include acid monoanhydrides such as maleic anhydride, phthalic anhydride, and itaconic anhydride, monoamine compounds such as aniline, cyclohexylamine, and n-butylamine, and monoisocyanate compounds such as phenyl isocyanate and naphthyl isocyanate. The proportion of the molecular weight modifier used is preferably 20 parts by mass or less per 100 parts by mass of the total of the tetracarboxylic dianhydride and diamine compounds used.

[0058] The synthesis reaction of the polyamic acid (P) is preferably carried out in an organic solvent, preferably at a reaction temperature of −20° C. to 150° C., and for a reaction time of 0.1 to 24 hours.

[0059] Examples of organic solvents used in the reaction include aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons. Particularly preferred organic solvents include one or more selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide, m-cresol, xylenol, and halogenated phenols. Alternatively, it is preferred to use a mixture of one or more of these solvents with other organic solvents (e.g., butyl cellosolve, diethylene glycol diethyl ether, etc.). The amount of organic solvent (a) used is preferably an amount such that the total amount (b) of the tetracarboxylic dianhydride and the diamine compound is 0.1 to 50% by mass relative to the total amount (a+b) of the reaction solution.

[0060] In this manner, a reaction solution containing the polyamic acid (P) dissolved therein is obtained. This reaction solution may be used directly for the preparation of a liquid crystal aligning agent, or the polyamic acid (P) contained in the reaction solution may be isolated and then used for the preparation of a liquid crystal aligning agent, or the isolated polyamic acid (P) may be purified and then used for the preparation of a liquid crystal aligning agent. When the polyamic acid (P) is subjected to dehydration ring closure to form a polyimide, the reaction solution may be used directly for the dehydration ring closure reaction, or the polyamic acid (P) contained in the reaction solution may be isolated and then used for the dehydration ring closure reaction, or the isolated polyamic acid (P) may be purified and then used for the dehydration ring closure reaction. The isolation and purification of the polyamic acid (P) can be carried out according to known methods.

[0061] (Polyamic acid ester) The polyamic acid ester as the polymer (P) (hereinafter also referred to as "polyamic acid ester (P)") can be obtained, for example, by [I] a method of reacting the polyamic acid (P) obtained by the above synthesis reaction with an esterifying agent; [II] a method of reacting a tetracarboxylic acid diester with a diamine compound containing a specific diamine; or [III] a method of reacting a tetracarboxylic acid diester dihalide with a diamine compound containing a specific diamine.

[0062] In this specification, "tetracarboxylic acid diester" means a compound in which two of the four carboxy groups in a tetracarboxylic acid are esterified and the remaining two are carboxy groups. "Tetracarboxylic acid diester dihalide" means a compound in which two of the four carboxy groups in a tetracarboxylic acid are esterified and the remaining two are halogenated.

[0063] Examples of the esterifying agent used in the method [I] include hydroxyl group-containing compounds, acetal compounds, halides, epoxy group-containing compounds, etc. Specific examples of these include: hydroxyl group-containing compounds such as alcohols (e.g., methanol, ethanol, and propanol), and phenols (e.g., phenol and cresol); acetal compounds such as N,N-dimethylformamide diethyl acetal and N,N-diethylformamide diethyl acetal; halides such as methyl bromide, ethyl bromide, stearyl bromide, methyl chloride, stearyl chloride, and 1,1,1-trifluoro-2-iodoethane; and epoxy group-containing compounds such as propylene oxide.

[0064] The tetracarboxylic acid diester used in the method [II] can be obtained, for example, by ring-opening the tetracarboxylic acid dianhydride exemplified in the description of the synthesis of the polyamic acid (P) using an alcohol such as methanol, ethanol, etc. The tetracarboxylic acid derivative used in the method [II] may be a tetracarboxylic acid diester alone, or may be used in combination with a tetracarboxylic acid dianhydride.

[0065] The tetracarboxylic acid diester dihalide used in the method [III] can be obtained, for example, by reacting the tetracarboxylic acid diester obtained as described above with a suitable chlorinating agent such as thionyl chloride. The tetracarboxylic acid derivative used in the method [III] may be the tetracarboxylic acid diester dihalide alone, or may be used in combination with a tetracarboxylic acid dianhydride.

[0066] The polyamic acid ester (P) contained in the liquid crystal aligning agent may have only an amic acid ester structure, or may be a partially esterified product in which an amic acid structure and an amic acid ester structure coexist. The reaction solution in which the polyamic acid ester (P) is dissolved may be used directly for preparing the liquid crystal aligning agent, or the polyamic acid ester (P) contained in the reaction solution may be isolated and then used for preparing the liquid crystal aligning agent, or the isolated polyamic acid ester (P) may be purified and then used for preparing the liquid crystal aligning agent. The polyamic acid ester (P) can be isolated and purified according to known methods.

[0067] (Polyimide) The polyimide as the polymer (P) (hereinafter also referred to as "polyimide (P)") can be obtained, for example, by dehydrating and ring-closing the polyamic acid (P) synthesized as described above to thereby imidize it.

[0068] The polyimide (P) may be a fully imidized product in which all amic acid structures contained in its precursor polyamic acid (P) have been dehydrated and cyclized, or a partially imidized product in which only a portion of the amic acid structures have been dehydrated and cyclized, resulting in both amic acid structures and imide ring structures. The polyimide (P) preferably has an imidization rate of 20% or more, more preferably 30 to 99%. The imidization rate is the ratio, expressed as a percentage, of the number of imide ring structures to the total number of amic acid structures and imide ring structures in the polyimide (P). Some of the imide rings may be isoimide rings.

[0069] The dehydration ring-closure of the polyamic acid (P) is preferably carried out by heating the polyamic acid (P), or by dissolving the polyamic acid (P) in an organic solvent, adding a dehydrating agent and a dehydration ring-closure catalyst to the solution, and heating as necessary.

[0070] In the method of adding a dehydrating agent and a dehydration ring-closing catalyst to a solution of polyamic acid (P), for example, an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride can be used as the dehydrating agent. The amount of the dehydrating agent used is preferably 0.01 to 20 mol per mol of the amic acid structure of the polyamic acid (P). The amount of the dehydration ring-closing catalyst used is preferably 0.01 to 10 mol per mol of the dehydrating agent used. Examples of organic solvents used in the dehydration ring-closing reaction include the organic solvents exemplified for use in the synthesis of polyamic acid (P). The reaction temperature for the dehydration ring-closing reaction is preferably 0 to 180°C, more preferably 10 to 150°C. The reaction time is preferably 1.0 to 120 hours, more preferably 2.0 to 30 hours.

[0071] In this way, a reaction solution containing polyimide (P) is obtained. This reaction solution may be used directly for the preparation of a liquid crystal aligning agent, or may be used for the preparation of a liquid crystal aligning agent after removing the dehydrating agent and the dehydration ring-closing catalyst from the reaction solution, or may be used for the preparation of a liquid crystal aligning agent after isolating polyimide (P), or may be used for the preparation of a liquid crystal aligning agent after purifying the isolated polyimide (P). These purification operations can be carried out according to known methods. Alternatively, polyimide (P) can also be obtained by imidizing polyamic acid ester (P).

[0072] The solution viscosity of the polymer (P) contained in the liquid crystal aligning agent is preferably 10 to 800 mPa·s when made into a 10% by mass solution, and more preferably 15 to 500 mPa·s. The solution viscosity (mPa·s) is a 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 (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

[0073] 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 5,000 to 100,000. The molecular weight distribution (Mw / Mn), which is expressed as the ratio of Mw to the number average molecular weight (Mn) measured by GPC in terms of polystyrene, is preferably 15 or less, and more preferably 10 or less.

[0074] In order to obtain a liquid crystal element that has excellent liquid crystal alignment properties, voltage retention characteristics, and AC afterimage characteristics while maintaining excellent mechanical properties of the liquid crystal alignment film, the content of the polymer (P) in the liquid crystal alignment agent is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, relative to the total mass of the solid content contained in the liquid crystal alignment agent (total mass of components other than the solvent of the liquid crystal alignment agent).

[0075] Although not limiting the present invention, it is believed that by forming a liquid crystal alignment film using a liquid crystal aligning agent containing a polymer having a specific partial structure in its main chain, the polymer having the specific partial structure in its main chain generates reactive species by isomerization due to light, heat, etc., and forms a crosslinked structure, thereby improving the mechanical properties of the liquid crystal alignment film. For example, in the case where the aromatic heterocycle is a pyridine ring, the substituted aromatic heterocycle moiety in the specific partial structure exhibits tautomerism as shown in the following scheme, which is believed to cause the crosslinking reaction to proceed. [ka] (In the scheme, R is a monovalent substituent. X is -CH2-, -NR 2 -, -O-, -S-, * 3 -NR 2 -CO-, * 3 -CO-NR 2 -, * 3 -NR 2 -CO-NR 3 -, * 3 -CO-O- or * 3 -O-CO-. R 2 and R 3is the same as above. 3 " represents the bond to the pyridine ring.)

[0076] <Other ingredients> The liquid crystal aligning agent of the present disclosure may further contain components other than the polymer (P) (hereinafter also referred to as "other components"). Examples of the other components include a polymer different from the polymer (P) (hereinafter also referred to as "polymer (Q)"), a crosslinking agent, a solvent, etc.

[0077] Polymer (Q) The polymer (Q) is a polymer that does not have a specific partial structure. The main skeleton of the polymer (Q) is not particularly limited. Examples of the polymer (Q) include polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane, polyester, polyenamine, polyurea, polyamide, polyamideimide, polyimine, polybenzoxazole precursor, polybenzoxazole, cellulose derivative, polyacetal, and addition polymer. Examples of the addition polymer include (meth)acrylic polymer, styrene polymer, maleimide polymer, (meth)acrylic-styrene copolymer, (meth)acrylic-maleimide copolymer, (meth)acrylic-styrene-maleimide copolymer, and styrene-maleimide copolymer.

[0078] Among these, polymer (Q) is preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane, and addition polymer, and more preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide, in that it exhibits good liquid crystal alignment properties and voltage retention characteristics when used in combination with polymer (P).

[0079] When the polymer (Q) is contained in the liquid crystal aligning agent, the content of the polymer (Q) is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 50% by mass or more, based on the total amount of the polymer (P) and the polymer (Q). The content of the polymer (Q) is preferably 95% by mass or less, more preferably 90% by mass or less, based on the total amount of the polymer (P) and the polymer (Q).

[0080] Crosslinking agent The liquid crystal aligning agent of the present disclosure may further contain a crosslinking agent. By further containing a crosslinking agent, it is possible to further reduce the occurrence of AC image retention in liquid crystal elements and further improve the quality retention against physical pressure acting during transportation of the liquid crystal device. Examples of crosslinking agents include compounds having two or more groups in the molecule of at least one type selected from the group consisting of cyclic ether groups, cyclic thioether groups, isocyanate groups, protected isocyanate groups, methylol groups, protected methylol groups, hydroxyalkylamide groups, protected hydroxyalkylamide groups, cyclic carbonate groups, polymerizable carbon-carbon bond-containing groups, protected amino groups, silanol groups, and alkoxysilyl groups.

[0081] From the viewpoint of sufficiently improving the mechanical properties of the liquid crystal alignment film and the AC afterimage properties of the liquid crystal element, the number of crosslinkable groups that the crosslinking agent has in one molecule is preferably 2 to 10, more preferably 2 to 6. The molecular weight of the crosslinking agent is preferably 100 to 1,000, more preferably 100 to 800, and even more preferably 100 to 700.

[0082] Specific examples of the crosslinking agent include compounds having a cyclic ether group or a cyclic thioether group, such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, triglycidyl isocyanurate, glycerol polyglycidyl ether, pentaerythritol tetraglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, N,N',N',N'-tetraglycidyl glycoluril, 1,6-hexanediol diglycidyl ether, trimethyl Examples of such glycerols include methyl glycerol propane triglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, N,N-diglycidyl-benzylamine, N,N-diglycidyl-aminomethylcyclohexane, N,N-diglycidyl-cyclohexylamine, and epoxidation reaction products of 2,2'-diallylbisphenol A diallyl ether with hydrogen peroxide.

[0083] Examples of compounds having an isocyanate group or a protected isocyanate group include tolylene diisocyanate, xylylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, compounds in which the isocyanate group of these compounds is protected with 3,6-dimethylpyrazole, methyl ethyl ketoxime, diethyl malonate, or ε-caprolactam, and compounds represented by the following formula (d1-1).

[0084] Examples of compounds having a methylol group or a protected methylol group include compounds represented by the following formulas (d2-1) to (d2-5). Examples of compounds having a hydroxyalkylamide group or a protected hydroxyalkylamide group include compounds represented by the following formulas (d3-1) to (d3-8). Examples of the compound having a cyclic carbonate group include compounds represented by the following formulas (d4-1) and (d4-2).

[0085] Examples of compounds having a polymerizable carbon-carbon bond-containing group include compounds having a (meth)acryloyl group, a maleimide group, an alkenyl group, a vinylphenyl group, a vinyl ether group, or a 3-methylenetetrahydrofuran-2(3H)-one-5-yl group. Specific examples of these include ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, pentaerythritol tri(meth)acrylate, and compounds represented by the following formulas (d5-1) to (d5-7).

[0086] Examples of compounds having a protected amino group include compounds represented by the following formulae (d6-1) to (d6-5). Examples of compounds having a silanol group or an alkoxysilyl group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, and vinyltriethoxysilane.

[0087] [ka] [ka] (In formula (d2-4), Ac is an acetyl group.) [ka] [ka] [ka] [ka]

[0088] When a crosslinking agent is contained in the liquid crystal aligning agent of the present disclosure, the content of the crosslinking agent is preferably 0.5 parts by mass or more relative to 100 parts by mass of the total amount of polymer components contained in the liquid crystal aligning agent (i.e., the total amount of polymer (P) and polymer (Q)), from the viewpoints of improving the mechanical properties of the liquid crystal alignment film and further reducing AC afterimages in liquid crystal elements. From the above viewpoints, the content of the crosslinking agent is more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, relative to 100 parts by mass of the total amount of polymer components. Furthermore, from the viewpoints of suppressing deterioration of liquid crystal alignment properties in liquid crystal elements and improving the storage stability of the liquid crystal aligning agent, the content of the crosslinking agent is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 7 parts by mass or less, relative to 100 parts by mass of the total amount of polymer components.

[0089] ·solvent The liquid crystal aligning agent of the present disclosure is prepared as a liquid composition in which the polymer (P) and components used as needed are dispersed or dissolved preferably in a suitable solvent.

[0090] Examples of the organic solvent to be used include N-methyl-2-pyrrolidone, γ-butyrolactone, γ-butyrolactam, N,N-dimethylformamide, N,N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, and 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, and the like.

[0091] In addition to the above, other components include, for example, antioxidants, metal chelate compounds, curing accelerators, surfactants, fillers, dispersants, photosensitizers, acid generators, base generators, radical generators, etc. The blending ratio of each of these components can be appropriately selected depending on each compound within a range that does not impair the effects of the present disclosure.

[0092] The solid content concentration in the liquid crystal aligning agent (the proportion of the total mass of the components other than the solvent of the liquid crystal aligning agent to the total mass of the liquid crystal aligning agent) is appropriately selected taking into consideration viscosity, volatility, etc., but is preferably in the range of 1 to 10 mass %. That is, the liquid crystal aligning agent is applied to the surface of a substrate as described below, and preferably heated to form a coating film that is a liquid crystal alignment film or a coating film that will become a liquid crystal alignment film. In this case, if the solid content concentration is 1 mass % or more, the coating film can have a sufficient thickness, and a good liquid crystal alignment film tends to be easily obtained. If the solid content concentration is 10 mass % or less, the coating film thickness does not become too large, and an increase in the viscosity of the liquid crystal aligning agent can be suppressed, tending to improve the coatability.

[0093] The particularly preferred range of solid content varies depending on the application of the liquid crystal aligning agent and the method used to apply the liquid crystal aligning agent to a substrate. For example, when applying a liquid crystal aligning agent for a liquid crystal display device to a substrate by a spinner method, the solid content (the ratio of the total mass of all components in the liquid crystal aligning agent other than the solvent to the total mass of the liquid crystal aligning agent) is particularly preferably in the range of 1.5 to 4.5 mass%. When using a printing method, the solid content is particularly preferably in the range of 3 to 9 mass%, thereby adjusting the solution viscosity to a range of 12 to 50 mPa·s. When using an inkjet method, the solid content is particularly preferably in the range of 1 to 5 mass%, thereby adjusting the solution viscosity to a range of 3 to 15 mPa·s. The temperature when preparing the liquid crystal aligning agent is preferably 10 to 50°C, more preferably 20 to 30°C. In addition, with regard to the liquid crystal aligning agent for the retardation film, from the viewpoint of the applicability of the liquid crystal aligning agent and the thickness of the coating film to be formed being appropriate, the solid content concentration of the liquid crystal aligning agent is preferably in the range of 0.2 to 10 mass %, more preferably in the range of 3 to 10 mass %.

[0094] <Liquid crystal alignment film and liquid crystal element> The liquid crystal alignment film of the present disclosure is formed using the liquid crystal aligning agent prepared as described above. Furthermore, the liquid crystal element of the present disclosure has a liquid crystal alignment film formed using the liquid crystal aligning agent described above. The operation mode of the liquid crystal in the liquid crystal element is not particularly limited, and various modes, such as TN type, STN type, VA type (including VA-MVA type, VA-PVA type, etc.), IPS (In-Plane Switching) type, FFS (Fringe Field Switching) type, OCB (Optically Compensated Bend) type, and PSA (Polymer Sustained Alignment) type, can be applied. The liquid crystal element can be manufactured, for example, by a method including the following steps 1 to 3. In step 1, different substrates are used depending on the desired operation mode. Steps 2 and 3 are common to all operation modes.

[0095] <Step 1: Formation of coating film> First, a liquid crystal alignment agent is applied to a substrate, and the coated surface is preferably heated to form a coating film on the substrate. Examples of substrates that can be used include glass, such as float glass or soda glass; and transparent substrates made of resins, such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, and poly(alicyclic olefin). When manufacturing TN, STN, or VA liquid crystal devices, two substrates with patterned transparent conductive films are used. On the other hand, when manufacturing IPS or FFS liquid crystal devices, one substrate with comb-shaped patterned electrodes and a counter substrate without electrodes are used. Examples of transparent conductive films that can be used include NESA films (registered trademark of PPG, USA) made of tin oxide (SnO), and ITO films made of indium oxide-tin oxide (InO-SnO). The liquid crystal alignment agent is applied to the substrate surface, preferably by offset printing, flexographic printing, spin coating, roll coating, or inkjet printing.

[0096] After the liquid crystal aligning agent is applied, preheating (pre-baking) is preferably carried out for the purpose of preventing dripping of the applied liquid crystal aligning agent. The pre-baking temperature is preferably 30 to 200°C, and the pre-baking time is preferably 0.25 to 10 minutes. Thereafter, a baking (post-baking) step is carried out for the purpose of removing the solvent in the applied liquid crystal aligning agent. The baking temperature (post-baking temperature) at this time is preferably 80 to 250°C, more preferably 80 to 200°C. The post-baking time is preferably 5 to 200 minutes. The thickness of the film thus formed is preferably 0.001 to 1 μm.

[0097] <Step 2: Alignment Treatment> When manufacturing a TN-type, STN-type, IPS-type, or FFS-type liquid crystal device, the coating film formed in step 1 is subjected to a treatment (alignment treatment) to impart liquid crystal alignment ability. This imparts the ability to align liquid crystal molecules to the coating film, resulting in a liquid crystal alignment film. Examples of alignment treatments that can be used include rubbing, in which the coating film formed on the substrate is rubbed in a certain direction with a roll wrapped with a cloth made of fibers such as nylon, rayon, or cotton; and photoalignment, in which the coating film formed on the substrate is irradiated with light to impart liquid crystal alignment ability to the coating film. On the other hand, when manufacturing a vertical alignment (VA)-type liquid crystal device, the coating film formed in step 1 can be used as is as a liquid crystal alignment film. Furthermore, the coating film may be subjected to an alignment treatment to further enhance the liquid crystal alignment ability. Liquid crystal alignment films suitable for vertical alignment-type liquid crystal devices are also suitable for PSA-type liquid crystal devices.

[0098] The light irradiation in the photo-alignment treatment can be performed by irradiating the coating film after the post-bake step, irradiating the coating film after the pre-bake step but before the post-bake step, or irradiating the coating film while it is being heated in at least one of the pre-bake and post-bake steps. In the photo-alignment treatment, the radiation to be irradiated to the coating film can be, for example, ultraviolet light and visible light containing light with a wavelength of 150 to 800 nm. Preferably, ultraviolet light containing light with a wavelength of 200 to 400 nm is used. When the radiation is polarized, it may be linearly polarized or partially polarized. Furthermore, when the radiation used is linearly polarized or partially polarized, irradiation may be performed from a direction perpendicular to the substrate surface, from an oblique direction, or a combination of these. When irradiating with unpolarized radiation, the irradiation direction is an oblique direction.

[0099] 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 400 to 20,000 J / m 2 and more preferably 1,000 to 5,000 J / m 2 The coating film may be irradiated with light while being heated in order to enhance the reactivity.

[0100] In producing a liquid crystal alignment film, the coating film that has been subjected to light irradiation treatment may be heated within a temperature range of 120°C or higher and 280°C or lower. Such a heat treatment is preferable in that it further improves the liquid crystal alignment (thermal realignment) and results in a liquid crystal device with improved display quality. This heating may be post-baking, or may be a heat treatment that is performed separately from post-baking and after post-baking. In the heat treatment of the coating film that has been subjected to light irradiation treatment, the heating temperature is preferably 140°C or higher, more preferably 150°C to 250°C, from the viewpoint of promoting realignment of molecular chains by heating. The heating time is preferably 5 to 200 minutes, more preferably 10 to 60 minutes.

[0101] The production of a liquid crystal alignment film may further include a step of contacting the light-irradiated coating film with water, a water-soluble organic solvent, or a mixed solvent of water and a water-soluble organic solvent. Examples of water-soluble organic solvents include methanol, ethanol, 1-propanol, isopropanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclopentanone. Among these, water, isopropanol, and mixtures thereof are preferred as the solvent used in this step. Examples of methods for contacting the coating film with the solvent include, but are not limited to, spraying, showering, immersion, and puddling. The contact time between the coating film and the solvent is not particularly limited, but is, for example, 5 seconds to 15 minutes. After contact with the solvent, the coating film may be subjected to a heat treatment.

[0102] <Step 3: Construction of liquid crystal cell> Two substrates with liquid crystal alignment films formed as described above are prepared, and a liquid crystal cell is fabricated between the two substrates, with the liquid crystal disposed adjacent to the liquid crystal alignment film. Examples of methods for fabricating a liquid crystal cell include placing two substrates facing each other with a gap between them so that the liquid crystal alignment films face each other, bonding the peripheries of the two substrates together with a sealant, injecting liquid crystal into the cell gap surrounded by the substrate surfaces and the sealant, and sealing the injection hole; an ODF method; and other methods. Examples of sealants that can be used include epoxy resins containing a curing agent and aluminum oxide spheres as spacers. Either positive-type or negative-type liquid crystals can be used. The use of negative-type liquid crystals in IPS-type and FFS-type liquid crystal elements is preferred because it reduces transmission loss above the electrodes and improves contrast. Furthermore, liquid crystals can include nematic liquid crystals and smectic liquid crystals, with nematic liquid crystals being preferred. In the PSA mode, a liquid crystal cell is constructed by placing a photopolymerizable compound together with liquid crystal between two substrates, and after the liquid crystal cell is constructed, a process is carried out in which the liquid crystal cell is irradiated with light while a voltage is applied between the conductive films on the pair of substrates.

[0103] For each mode of liquid crystal cell, a polarizing plate is then attached to the outer surface of the liquid crystal cell as needed to form a liquid crystal element. Examples of polarizing plates include a polarizing film called an "H film" made by stretching and aligning polyvinyl alcohol and absorbing iodine, sandwiched between cellulose acetate protective films, and a polarizing plate made of the H film itself.

[0104] The liquid crystal element of the present disclosure can be effectively applied to various applications, specifically, for example, various display devices such as watches, portable game machines, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, liquid crystal televisions, and information displays, as well as light control films, retardation films, and the like.

[0105] According to the above explanation, the following aspects [1] to

[13] are included. [1] A liquid crystal aligning agent containing a polymer (P) having a partial structure represented by the above formula (1) in its main chain. [2] The liquid crystal aligning agent according to [1], wherein the polymer [P] is at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide. [3] The monovalent substituent directly bonded to the aromatic heterocycle is an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, a hydroxy group, an alkoxy group having 1 to 5 carbon atoms, a thioalkoxy group having 1 to 5 carbon atoms, a hydroxyalkyl group having 1 to 5 carbon atoms, an alkoxyalkyl group having 1 to 5 carbon atoms, or 3 -NR 6 R 7 , * 3 -OC(=O)-R 7 , * 3 -NR 6 -C(=O)-R 7 , and * 3 -NR 6 -C(=O)-NR 7 R 8 (However, R 6 , R 7 and R 8 are each independently a hydrogen atom or a monovalent organic group.3 " represents a bond to an aromatic heterocycle.) The liquid crystal aligning agent according to [1] or [2], wherein the liquid crystal aligning agent is at least one selected from the group consisting of: [4] Z in the above formula (1) 1 and Z 2 The liquid crystal aligning agent according to any one of [1] to [3], which is different from [5] Ar in the above formula (1) 1 and Ar 2 The liquid crystal aligning agent according to any one of [1] to [4], which is different from [6] The liquid crystal aligning agent according to any one of [1] to [5], wherein the aromatic heterocycle is a pyridine ring, a pyrimidine ring, or a pyrazine ring. [7] The liquid crystal aligning agent according to any one of [1] to [6], wherein the polymer (P) contains a structural unit derived from a diamine having a partial structure represented by the above formula (1). [8] The liquid crystal aligning agent according to any one of [1] to [7], wherein the diamine is represented by the above formula (2). [9] The liquid crystal aligning agent according to any one of [1] to [8], further comprising a crosslinking agent.

[10] A liquid crystal alignment film formed using the liquid crystal aligning agent according to any one of [1] to [9].

[11] A method for producing a liquid crystal alignment film, comprising the steps of forming a coating film using the liquid crystal aligning agent according to any one of [1] to [9], and subjecting the coating film to a light irradiation treatment to impart liquid crystal alignment ability.

[12] The method for producing a liquid crystal alignment film according to

[11] , further comprising a step of heating the coating film that has been subjected to the light irradiation treatment at 120°C or higher and 280°C or lower.

[13] A liquid crystal device comprising the liquid crystal alignment film according to

[10] or the liquid crystal alignment film produced by the method according to

[11] or

[12] . [Example]

[0106] The present invention will be explained in more detail below with reference to examples, but the present invention should not be construed as being limited by these examples.

[0107] In the following examples, the imidization rate of polyimide in a polymer solution was measured by the following method. [Imidization rate of polyimide] The polyimide solution was poured into pure water, and the resulting precipitate was thoroughly dried under reduced pressure at room temperature. After that, it was dissolved in deuterated dimethyl sulfoxide and measured at room temperature using tetramethylsilane as a standard substance. 1 H-NMR measurement was carried out. 1 The imidization rate [%] was calculated from the H-NMR spectrum using the following formula (1). Imidization rate [%] = (1 - (A 1 / (A 2 ×α)))×100 …(1) (In formula (1), A 1 is the peak area due to the proton of the NH group, which appears at a chemical shift of around 10 ppm. 2 is the peak area due to other protons. α is the ratio of the number of other protons to one proton of the NH group in the polymer precursor (polyamic acid).

[0108] In the following examples, the synthesis on the synthesis scale shown in the following synthesis examples was repeated as necessary to ensure the required amounts of raw material compounds and polymers. Note that "parts" and "%" in the examples and comparative examples are by mass unless otherwise specified.

[0109] The abbreviations for the compounds are as follows: In the following, the compound represented by formula (X) may be simply referred to as "compound (X)".

[0110] (Tetracarboxylic acid dianhydride) [ka]

[0111] (Diamine compounds) Specific diamines [ka] [ka] [ka] [ka] [ka]

[0112] Other diamines [ka] [ka] [ka] [ka]

[0113] (additives) [ka]

[0114] <Polymer synthesis> 1. Synthesis of polyamic acid [Synthesis Example 1] 100 parts by mole of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride (compound (b-1)) as a tetracarboxylic dianhydride, 50 parts by mole of compound (DA-1) and 50 parts by mole of compound (a-1) as diamine compounds were dissolved in N-methyl-2-pyrrolidone (NMP), and the reaction was carried out at 40°C for 6 hours to obtain a solution containing 15% by mass of polyamic acid (referred to as polymer (PAA-1)).

[0115] [Synthesis Examples 2-94, 103-110] Polyamic acids (polymers (PAA-2) to (PAA-69) and polymers (paa-1) to (paa-33)) were obtained by the same procedure as in Synthesis Example 1, except that the types and amounts of the tetracarboxylic dianhydrides and diamine compounds used were changed as shown in Tables 1 to 3. In Table 1, the numerical values ​​for the tetracarboxylic dianhydrides (acid dianhydrides 1 to 3) represent the ratio (molar ratio) of each compound to 100 parts by mole of the total amount of the tetracarboxylic dianhydrides used in the synthesis of each polyamic acid. The numerical values ​​for the diamine compounds (diamines 1 to 4) represent the ratio (molar ratio) of each compound to 100 parts by mole of the total amount of the diamine compounds used in the synthesis of each polyamic acid.

[0116] [Table 1]

[0117] [Table 2]

[0118] [Table 3]

[0119] 2. Polyimide Synthesis [Synthesis Example 95] A solution containing 15% by mass of polymer (PAA-33) was obtained by the same procedure as in Synthesis Example 33. Next, NMP was added to the obtained polyamic acid solution to make a solution with a polyamic acid concentration of 10% by mass, and pyridine and acetic anhydride were added to carry out a dehydration ring-closing reaction at 60°C for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with fresh NMP to obtain a solution containing 15% by mass of polyimide with an imidization rate of approximately 80% (referred to as polymer (PI-1)).

[0120] [Synthesis Example 96] A solution containing 15% by mass of polymer (PAA-30) was obtained by the same procedure as in Synthesis Example 30. Next, NMP was added to the obtained polyamic acid solution to make a solution with a polyamic acid concentration of 10% by mass, and pyridine and acetic anhydride were added to carry out a dehydration ring-closing reaction at 60°C for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with fresh NMP to obtain a solution containing 15% by mass of polyimide with an imidization rate of approximately 80% (referred to as polymer (PI-2)).

[0121] [Synthesis Example 97] A solution containing 15% by mass of polymer (PAA-31) was obtained by the same procedure as in Synthesis Example 31. Next, NMP was added to the obtained polyamic acid solution to make a solution with a polyamic acid concentration of 10% by mass, and pyridine and acetic anhydride were added to carry out a dehydration ring-closing reaction at 60°C for 4 hours. The amounts of pyridine and acetic anhydride added were adjusted to 0.6 times the amounts used in Synthesis Example 95. After the dehydration ring-closing reaction, the solvent in the system was replaced with fresh NMP to obtain a solution containing 15% by mass of polyimide with an imidization rate of approximately 60% (referred to as polymer (PI-3)).

[0122] [Synthesis Example 98] A solution containing 15% by mass of polymer (PAA-38) was obtained by the same procedure as in Synthesis Example 38. Next, NMP was added to the obtained polyamic acid solution to make a solution with a polyamic acid concentration of 10% by mass, and pyridine and acetic anhydride were added to carry out a dehydration ring-closing reaction at 60°C for 4 hours. The amounts of pyridine and acetic anhydride added were adjusted to 0.6 times the amounts used in Synthesis Example 95. After the dehydration ring-closing reaction, the solvent in the system was replaced with fresh NMP to obtain a solution containing 15% by mass of polyimide with an imidization rate of approximately 50% (referred to as polymer (PI-4)).

[0123] [Synthesis Example 99] A solution containing 15% by mass of polymer (paa-9) was obtained by the same procedure as in Synthesis Example 76. Next, NMP was added to the obtained polyamic acid solution to make a solution with a polyamic acid concentration of 10% by mass, and pyridine and acetic anhydride were added to carry out a dehydration ring-closing reaction at 60°C for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with fresh NMP to obtain a solution containing 15% by mass of polyimide with an imidization rate of approximately 80% (referred to as polymer (pi-1)).

[0124] [Synthesis Example 100] A solution containing 15% by mass of polymer (paa-6) was obtained by the same procedure as in Synthesis Example 73. Next, NMP was added to the obtained polyamic acid solution to make a solution with a polyamic acid concentration of 10% by mass, and pyridine and acetic anhydride were added to carry out a dehydration ring-closing reaction at 60°C for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with fresh NMP to obtain a solution containing 15% by mass of polyimide with an imidization rate of approximately 80% (referred to as polymer (pi-2)).

[0125] [Synthesis Example 101] A solution containing 15% by mass of polymer (paa-10) was obtained by the same procedure as in Synthesis Example 77. Next, NMP was added to the obtained polyamic acid solution to make a solution with a polyamic acid concentration of 10% by mass, and pyridine and acetic anhydride were added to carry out a dehydration ring-closing reaction at 60°C for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with fresh NMP to obtain a solution containing 15% by mass of polyimide with an imidization rate of approximately 80% (referred to as polymer (pi-3)).

[0126] [Synthesis Example 102] A solution containing 15% by mass of polymer (paa-11) was obtained by the same procedure as in Synthesis Example 78. Next, NMP was added to the obtained polyamic acid solution to make a solution with a polyamic acid concentration of 10% by mass, and pyridine and acetic anhydride were added to carry out a dehydration ring-closing reaction at 60°C for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with fresh NMP to obtain a solution containing 15% by mass of polyimide with an imidization rate of approximately 80% (referred to as polymer (pi-4)).

[0127] <Preparation and Evaluation of Liquid Crystal Alignment Agent> [Example 1: Optical FFS type liquid crystal display element] 1. Preparation of Liquid Crystal Alignment Agent A solution containing 40 parts by mass of the polymer (PAA-1) obtained in Synthesis Example 1 (solid content), 60 parts by mass of the polymer (paa-21) obtained in Synthesis Example 88 (solid content), 4 parts by mass of compound (N-3), and 1 part by mass of compound (N-5) were mixed and diluted with NMP, N-ethyl-2-pyrrolidone (NEP), gamma butyrolactone (BL), and butyl cellosolve (BC) to obtain a solution with a solvent composition of NMP / NEP / BL / BC = 15 / 45 / 20 / 20 (mass ratio) and a solids concentration of 3.5 mass%. This solution was filtered through a filter with a pore size of 0.2 μm to prepare a liquid crystal alignment agent (AL-1).

[0128] 2. Fabrication of FFS-type LCD elements using the photoalignment method A glass substrate (referred to as the first substrate) with a flat electrode (bottom electrode), an insulating layer, and a comb-shaped electrode (top electrode) laminated in this order on one side, and a glass substrate (referred to as the second substrate) without an electrode were prepared. Next, a liquid crystal alignment agent (AL-1) was applied to the electrode-forming surface of the first substrate and one substrate surface of the second substrate using a spinner, and heated (pre-baked) on a hot plate at 80°C for 1 minute. This was followed by drying (post-baking) for 30 minutes in an oven at 230°C with the interior replaced with nitrogen, forming a coating film with an average thickness of 0.1 μm. The resulting coating film was irradiated with 5,000 J / m of linearly polarized ultraviolet light containing a 254 nm emission line using an Hg-Xe lamp. 2 The coating film was then irradiated with light from the normal direction of the substrate to perform a photo-alignment treatment. The irradiation dose was measured using an actinometer measuring at a wavelength of 254 nm. The photo-aligned coating film was then heat-treated in a clean oven at 230°C for 30 minutes to form a liquid crystal alignment film. Next, an epoxy resin adhesive containing 3.5 μm diameter aluminum oxide spheres was applied by screen printing to the outer edge of the surface of one of the pair of substrates on which the liquid crystal alignment film was formed. The substrates were then superimposed and pressed together so that the projection directions of the polarization axes on the substrate surfaces during light irradiation were antiparallel, and the adhesive was thermally cured at 150°C for 1 hour. Next, a negative liquid crystal (MLC-6608, manufactured by Merck) was filled between the pair of substrates through the liquid crystal injection port, which was then sealed with an epoxy adhesive to obtain a liquid crystal cell. Furthermore, to eliminate flow alignment during liquid crystal injection, the cell was heated at 120°C and then slowly cooled to room temperature. The above series of operations was also performed with a post-baking UV irradiation dose of 100 to 10,000 J / m. 2 Three or more liquid crystal cells with different UV exposure doses were manufactured by changing the exposure dose within the range of , and the liquid crystal cell with the exposure dose that showed the best alignment characteristics (optimum exposure dose) was used for the evaluation of AC image retention characteristics, alignment uniformity, VHR reliability, and bright spot defect resistance described below.

[0129] 3. Evaluation of AC image lag characteristics using retardation change rate The liquid crystal cell manufactured in 2 above was set to a 27,000 cd / m 2 The cells were left standing for 500 hours in front of a high-brightness backlight, and AC image retention was evaluated based on the rate of change in retardation before and after backlight irradiation. First, the retardation of the liquid crystal cells manufactured in 2 above was measured using an Axoscan manufactured by Optoscience, and the rate of change α in retardation before and after backlight irradiation was calculated using the following formula (z-1). The smaller the rate of change α, the more stable the liquid crystal alignment and the better the AC image retention characteristics. A rate of change α of 1% or less was rated as "good (○)," a rate of change α between 1% and 2% was rated as "fair (△)," and a rate of change α greater than 2% was rated as "poor (×)." α=Δθ / θ1 …(z-1) (In formula (z-1), Δθ represents the difference in retardation before and after irradiation, and θ1 represents the retardation value before irradiation.) As a result, the AC afterimage characteristics of this example were evaluated as "good (◯)."

[0130] 4. Evaluation of alignment uniformity Using the liquid crystal cell manufactured in 2. above, retardation was measured at 20 arbitrary points within one pixel plane using an Axoscan manufactured by Optoscience, and the standard deviation was calculated. The evaluation was as follows: if the standard deviation of retardation was 0.05 or less, it was "good (○)", if it was greater than 0.05 and less than 0.07, it was "fair (△)", and if it was greater than 0.07, it was "poor (×)". As a result, the alignment uniformity of this example was evaluated as "good (○)".

[0131] 5. Evaluation of VHR reliability The liquid crystal cell manufactured in 2 above was evaluated for reliability in terms of voltage holding ratio. The evaluation was performed as follows. First, a voltage of 1 V was applied to the liquid crystal cell for 60 microseconds, and then the voltage holding ratio (VHR1) was measured 1670 milliseconds after the application was removed. Next, the liquid crystal cell was irradiated with CCFL (backlight) at 60°C for one week, and then left to cool naturally at room temperature. After cooling, a voltage of 1 V was applied to the liquid crystal cell for 60 microseconds, and then the voltage holding ratio (VHR2) was measured 1670 milliseconds after the application was removed. The measurement device used was a VHR measuring device "VHR-1" manufactured by Toyo Corporation. The rate of change in VHR (ΔVHR) at this time was calculated as the difference between VHR1 and VHR2 (ΔVHR = VHR1 - VHR2), and VHR reliability was evaluated based on ΔVHR. If ΔVHR was less than 15%, it was judged as "good (○)", if it was between 15% and 20%, it was judged as "fair (△)", and if it was more than 20%, it was judged as "poor (×)". As a result, the VHR reliability of this example was evaluated as "good (○)".

[0132] 6. Evaluation of film strength (rubbing resistance) The liquid crystal alignment agent (AL-1) prepared in 1. above was applied to a glass substrate using a spinner and heated (pre-baked) on a hot plate at 110°C for 3 minutes. The substrate was then dried (post-baked) for 30 minutes in a nitrogen-purged oven at 230°C to form a coating film with an average thickness of 0.1 μm. The haze value of this coating film was measured using a haze meter. The coating film was then rubbed five times using a rubbing machine equipped with a roll wrapped around a cotton cloth at a roll rotation speed of 1000 rpm, a stage movement speed of 3 cm / sec, and a pile indentation length of 0.3 mm. The haze value of the liquid crystal alignment film was then measured using a haze meter, and the difference from the haze value before and after rubbing (haze change) was calculated. If the haze value of the film before rubbing is Hz1 (%) and the haze value of the film after rubbing is Hz2 (%), the haze change is expressed by the following formula (z-2): Haze change value (%) = Hz2 - Hz1 ... (z-2) When the haze change value of the liquid crystal alignment film was less than 0.2, it was evaluated as "good (○)", when the haze change value was 0.2 or more and 0.5 or less, it was evaluated as "fair (△)", and when it was more than 0.5, it was evaluated as "poor (×)". If the haze change value is 0.5 or less (more preferably less than 0.2), it can be said that the film strength is sufficiently high and the rubbing resistance is high, that is, the mechanical properties of the film are good. As a result, in this example, it was evaluated as "good (○)".

[0133] 7. Evaluation of Bright Spot Resistance The bright spot defect resistance of the liquid crystal cell manufactured in 2 above was evaluated. The bright spots of the liquid crystal cell were evaluated by observing the liquid crystal cell with a polarizing microscope and counting the number of bright spots. First, the liquid crystal cell was placed in a crossed Nicol position and observed with a polarizing microscope at 5x magnification to count the number of bright spots in the initial state. Then, the liquid crystal cell was left standing in an oven at 100°C for 100 hours, and the number of bright spots was counted in the same way. The number of bright spots after leaving the liquid crystal cell standing in the oven for 100 hours was compared with the number of bright spots in the initial state, and an increase in the number of bright spots from the initial state of less than 10 was evaluated as "good (○)", 10 to 20 was evaluated as "fair (△)", and 20 or more was evaluated as "poor (×)". As a result, this example was evaluated as "fair (△)".

[0134] [Examples 2 to 82 and Comparative Examples 1 to 18] Liquid crystal alignment agents were prepared in the same manner as in Example 1, except that the composition of the liquid crystal alignment agent was changed as shown in Tables 4 to 7. Furthermore, using the obtained liquid crystal alignment agent, an FFS-type liquid crystal cell was produced by a photoalignment method in the same manner as in Example 1, and various evaluations were carried out. The results are shown in Tables 4 to 7. The numerical values ​​in the mass ratio column represent the blending ratio (parts by mass) of the solid content of each compound (polymer, additive) relative to 100 parts by mass of the total amount of the polymer components used in preparing the liquid crystal alignment agent.

[0135] [Table 4]

[0136] [Table 5]

[0137] [Table 6]

[0138] [Table 7]

[0139] As shown in Tables 4 to 7, the liquid crystal alignment agents of Examples 1 to 82, which contain a polymer having a specific partial structure in its main chain, showed well-balanced improvements in AC image retention characteristics, alignment uniformity, VHR reliability, film strength, and bright spot defect resistance compared to the liquid crystal alignment agents of Comparative Examples 1 to 18, which contain a polymer not having a specific partial structure in its main chain instead of a polymer having a specific partial structure in its main chain.

[0140] Among them, the liquid crystal alignment agents of Examples 19 to 28, 34 to 39, 44, 46 to 50, 62 to 72, and 76 to 82 were all rated "good (○)" for AC image retention characteristics, alignment uniformity, VHR reliability, film strength, and resistance to bright spot defects, demonstrating that electrical properties (VHR reliability), film strength, and resistance to bright spot defects can be improved while maintaining liquid crystal alignment. This is thought to be because the specific partial structure introduced into the main chain of the polymer has a substituted aromatic heterocycle and an appropriate spacer length, which enables the liquid crystal alignment, mechanical properties, and electrical properties to be expressed in a balanced manner, and the asymmetric structure prevents decomposition products from precipitating in the liquid crystal, thereby improving resistance to bright spot defects.

[0141] [Example 83: Rubbed FFS-type liquid crystal display element] 1. Preparation of Liquid Crystal Alignment Agent A mixture of 40 parts by mass of a solution containing the polymer (PAA-44) obtained in Synthesis Example 44 (solid content), 60 parts by mass of a solution containing the polymer (paa-22) obtained in Synthesis Example 89 (solid content), 4 parts by mass of compound (N-3), and 1 part by mass of compound (N-5) was diluted with NMP, NEP, and butyl cellosolve (BC) to obtain a solution with a solvent composition of NMP / NEP / BC=20 / 40 / 40 (mass ratio) and a solids concentration of 3.5% by mass. This solution was filtered through a filter with a pore size of 0.2 μm to prepare a liquid crystal alignment agent (AL-101).

[0142] 2. Fabrication of FFS-type LCD elements using the rubbing method A glass substrate (referred to as the first substrate) with a flat electrode (bottom electrode), an insulating layer, and a comb-shaped electrode (top electrode) laminated in this order on one side thereof, and a glass substrate (referred to as the second substrate) without an electrode, were prepared. Next, a liquid crystal alignment agent (AL-101) was applied to the electrode-formed surface of the first substrate and one side of the second substrate using a spinner and heated (pre-baked) on a hot plate at 110°C for 3 minutes. This was then dried (post-baked) for 30 minutes in a nitrogen-purged oven at 230°C to form a coating film with an average thickness of 0.08 μm. The coating film surface was then rubbed using a rubbing machine equipped with a roll wrapped around a rayon cloth at a roll rotation speed of 1000 rpm, a stage movement speed of 3 cm / sec, and a pile depth of 0.3 mm. This was followed by ultrasonic cleaning in ultrapure water for 1 minute and then drying in a clean oven at 100°C for 10 minutes to obtain a pair of substrates with liquid crystal alignment films. Next, a pair of substrates with liquid crystal alignment films were screen-printed with an epoxy resin adhesive containing 3.5 μm diameter aluminum oxide spheres, leaving a liquid crystal injection port at the edge of the surface where the liquid crystal alignment film was formed. The substrates were then stacked and pressed together, and the adhesive was thermally cured at 150°C for 1 hour. Next, negative liquid crystal (MLC-6608, manufactured by Merck) was injected into the gap between the pair of substrates through the liquid crystal injection port, and the liquid crystal injection port was then sealed with an epoxy adhesive. To eliminate flow alignment during liquid crystal injection, the substrates were heated to 120°C and then slowly cooled to room temperature to produce a liquid crystal cell. When stacking the pair of substrates, the rubbing directions of each substrate were antiparallel.

[0143] 3. Evaluation The liquid crystal cells manufactured in 2 above were evaluated for AC image retention, alignment uniformity, VHR reliability, and bright spot defect resistance in the same manner as in Example 1. In addition, the rubbing resistance was evaluated using a liquid crystal alignment agent (AL-101) in the same manner as in Example 1. The evaluation results are shown in Table 5.

[0144] [Examples 84 to 88 and Comparative Examples 19 to 24] A liquid crystal alignment agent was prepared in the same manner as in Example 83, except that the composition of the liquid crystal alignment agent was changed as shown in Table 6. In addition, an FFS-type liquid crystal cell was produced by the rubbing method in the same manner as in Example 83 using the obtained liquid crystal alignment agent, and various evaluations were performed. The results are shown in Table 6. In Table 8, the numerical values ​​in the mass ratio column represent the blending ratio (parts by mass) of the solid content of each compound (polymer, additive) relative to 100 parts by mass of the total amount of the polymer components used in preparing the liquid crystal alignment agent.

[0145] [Table 8]

[0146] As shown in Table 8, the liquid crystal alignment agents of Examples 83 to 88, which contain a polymer having a specific partial structure in its main chain, showed a balanced improvement in AC image retention characteristics, alignment uniformity, VHR reliability, film strength, and resistance to bright spot defects, compared to the liquid crystal alignment agents of Comparative Examples 19 to 24, which contain a polymer not having a specific partial structure in its main chain instead of a polymer having a specific partial structure in its main chain.

[0147] From the above results, it has become clear that a liquid crystal alignment agent containing a polymer having a partial structure represented by the above formula (1) in its main chain can produce liquid crystal elements with excellent AC image retention characteristics, alignment uniformity, bright spot defect resistance, and VHR reliability, and can also form a liquid crystal alignment film with excellent mechanical properties.

Claims

1. A liquid crystal aligning agent comprising a polymer (P) having a partial structure represented by the following formula (1) in its main chain: 【Chemistry 1】 (In formula (1), Ar １ and Ar ２ are each independently a divalent aromatic ring group. １ and Ar ２ At least one of Z has an aromatic heterocycle having at least one element selected from the group consisting of nitrogen, oxygen, and sulfur, and a monovalent substituent directly bonded to the aromatic heterocycle. １ and Z ２ are each independently a single bond, -NR ２ -, -O-, -S-, -CO-, * １ -NR ２ -CO-, * １ -CO-NR ２ -, * １ -NR ２ -CO-NR ３ -, * １ -CO-O- or * １ -O-CO-. ２ and R ３ are each independently a hydrogen atom or a monovalent organic group. １ " is Ar １ or Ar ２ It represents a bond with L. １ is -NR ４ -, -O-, -S-, -CO-, * ２ -NR ４ -CO-, * ２ -CO-NR ４ -, -NR ４ -CO-NR ５ -, * ２ -CO-O- or * ２ -O-CO-. ４ and R ５ are each independently a hydrogen atom or a monovalent organic group. ２ " is B １ represents a bond with B. １ and B ２ are each independently a single bond or a divalent chain hydrocarbon group having 1 to 8 carbon atoms, and n is 0 or 1. However, Ar １ and Ar ２ The number of atoms constituting the main chain of the polymer in which the group connecting

2. The liquid crystal aligning agent according to claim 1 , wherein the polymer [P] is at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide.

3. The monovalent substituent directly bonded to the aromatic heterocycle is an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, a hydroxy group, an alkoxy group having 1 to 5 carbon atoms, a thioalkoxy group having 1 to 5 carbon atoms, a hydroxyalkyl group having 1 to 5 carbon atoms, an alkoxyalkyl group having 1 to 5 carbon atoms, ３ -NR ６ R ７ , * ３ -OC(=O)-R ７ , * ３ -NR ６ -C(=O)-R ７ , and * ３ -NR ６ —C(═O)—NR ７ R ８ (However, R ６ , R ７ and R ８ are each independently a hydrogen atom or a monovalent organic group. ３ " represents a bond to the aromatic heterocycle.) The liquid crystal aligning agent according to claim 1, wherein the compound is at least one selected from the group consisting of:

4. Z in the above formula (1) １ and Z ２ The liquid crystal aligning agent according to claim 1 , wherein

5. Ar in the above formula (1) １ and Ar ２ The liquid crystal aligning agent according to claim 1 , wherein

6. The liquid crystal aligning agent according to claim 1 , wherein the aromatic heterocycle is a pyridine ring, a pyrimidine ring, or a pyrazine ring.

7. The liquid crystal aligning agent according to claim 1 , wherein the polymer (P) contains a structural unit derived from a diamine having a partial structure represented by the formula (1).

8. The liquid crystal aligning agent according to claim 1 , wherein the diamine is represented by the following formula (2): 【Chemistry 2】 (In formula (2), Ar １ , Ar ２ , Z １ , Z ２ , L １ , B １ , B ２ and n have the same meanings as in formula (1) above.

9. The liquid crystal aligning agent according to claim 1 , further comprising a crosslinking agent.

10. A liquid crystal alignment film formed using the liquid crystal aligning agent according to any one of claims 1 to 9.

11. A method for producing a liquid crystal alignment film, comprising the steps of forming a coating film using the liquid crystal aligning agent according to any one of claims 1 to 9, and subjecting the coating film to a light irradiation treatment to impart liquid crystal alignment ability.

12. The method for producing a liquid crystal alignment film according to claim 11, further comprising a step of heating the coating film that has been subjected to the light irradiation treatment at 120°C or more and 280°C or less.

13. A liquid crystal device comprising the liquid crystal alignment film according to claim 10.

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