Liquid crystal aligning agent for forming weak anchoring film, method for producing liquid crystal alignment film, and method for producing liquid crystal element

Abstract

To provide a liquid crystal aligning agent for forming a weak anchoring film capable of forming a liquid crystal alignment film for obtaining a liquid crystal element which exhibits good liquid crystal alignment property and alignment uniformity and can be driven at a low voltage while having high luminance.SOLUTION: The liquid crystal aligning agent for forming a weak anchoring film is used for forming a weak anchoring liquid crystal alignment film and contains a polymer (P) having at least one selected from the group consisting of a specific cinnamate structure, a partial structure having a specific nitrogen-containing aromatic heterocycle, an azobenzene structure, a chalcone structure, a coumarin structure and a chromanone structure.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a weak anchoring liquid crystal aligning agent, a method for producing a liquid crystal alignment film, and a method for producing a liquid crystal element. [Background technology]

[0002] In liquid crystal devices, the initial alignment of liquid crystal molecules is generally determined by the anchoring of the liquid crystal molecules by a liquid crystal alignment film. In recent years, various liquid crystal devices have been proposed for horizontal alignment mode liquid crystal devices, such as IPS and FFS types, in which a liquid crystal alignment film with strong anchoring energy (hereinafter also referred to as a "strong anchoring liquid crystal alignment film") is formed on one of a pair of substrates, and a liquid crystal alignment film with no or very low anchoring energy (hereinafter also referred to as a "weak anchoring liquid crystal alignment film") is formed on the other substrate. Liquid crystal devices utilizing the weak anchoring state are said to be able to achieve improved brightness and contrast ratio, low-voltage operation, etc., compared to conventional liquid crystal devices in which strong anchoring liquid crystal alignment films are formed on both substrates. Note that "weak anchoring" is also called "zero-plane anchoring."

[0003] For example, Patent Document 1 discloses a method for manufacturing a liquid crystal cell by forming a zero-plane anchoring film on a first substrate using a method including a step of contacting a liquid crystal composition containing liquid crystal and a radically polymerizable compound with a radical-generating film and applying sufficient energy to polymerize the radically polymerizable compound, and then forming a liquid crystal alignment film on a second substrate using a known liquid crystal alignment agent. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 004433 Summary of the Invention [Problem to be solved by the invention]

[0005] In the technology described in Patent Document 1, the preparation of a weak anchoring liquid crystal alignment film requires a step of contacting a liquid crystal composition containing liquid crystal and a radically polymerizable compound with a radical-generating film formed on a first substrate, and applying sufficient energy to cause a polymerization reaction of the radically polymerizable compound in that state. From the viewpoint of productivity, it is desirable to have a liquid crystal element that can prepare a weak anchoring liquid crystal alignment film by a simple procedure, can achieve low-voltage driving due to the weak anchoring state, and exhibits good liquid crystal alignment and alignment uniformity while improving brightness.

[0006] The present invention has been made in consideration of the above-mentioned problems, and its main object is to provide a liquid crystal alignment agent for forming a weak anchoring film that can form a liquid crystal alignment film to obtain a liquid crystal element that exhibits good liquid crystal alignment properties and alignment uniformity, and that can be driven at a low voltage while having high brightness. [Means for solving the problem]

[0007] According to the present invention, there are provided the following liquid crystal aligning agent for forming a weak anchoring film, a method for producing a liquid crystal alignment film, and a method for producing a liquid crystal element.

[0008] [1] A liquid crystal aligning agent for forming a weak anchoring film, which is used to form a weak anchoring liquid crystal alignment film, and which contains a polymer (P) having at least one structure selected from the group consisting of a partial structure represented by the following formula (1), a partial structure represented by the following formula (2), a partial structure represented by the following formula (3), a partial structure represented by the following formula (4), an azobenzene structure, a chalcone structure, a coumarin structure, and a chromanone structure. [ka] (In formula (1), A 1 and A 2 are each independently an aromatic ring group. 1 and Y 2 are each independently a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 10 carbon atoms.1 is an oxygen atom or -NR 3 -R 3 is a hydrogen atom or a monovalent organic group. n1 is an integer of 0 to 2. When n1 is 2, a plurality of A 1 are the same or different. 1 " represents a bond to an atom contained in the polymer main chain.) [ka] (In formula (2), A 1 and A 2 are each independently an aromatic ring group. n1 is 0 or 1. Y 1 and Y 2 are each independently a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 10 carbon atoms. 1 is an oxygen atom or -NR 3 -R 3 is a hydrogen atom or a monovalent organic group. 2 is a single bond, an oxygen atom, or -NR 4 -R 4 is a hydrogen atom or a monovalent organic group. 2 represents an alkanediyl group having 1 to 10 carbon atoms, a fluoroalkanediyl group having 1 to 10 carbon atoms, a divalent aliphatic ring group, or a divalent aromatic ring group. n2 is 0 or 1. Z 1 represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, -NR 5 R 6 R is a nitrile group, a substituted or unsubstituted alkynyl group, an acetyl group, a trifluoromethyl group, or a fluorine atom. 5 and R 6 are each independently an alkyl group having 1 to 16 carbon atoms. 1 represents an alkanediyl group having 1 to 10 carbon atoms, or an alkanediyl group having 2 to 10 carbon atoms in which one or more methylene groups are -O-, -S-, or -NR 7 -, -CO-, -CO-O- or -CO-NR 7 - is a divalent group in which R 7 is a hydrogen atom or a monovalent organic group. "*" represents a bond. [ka] (In formula (3), A 1 and A 2 are each independently an aromatic ring group. 1 and Y 2 are each independently a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 10 carbon atoms. 1 is an oxygen atom or -NR 3 -R 3 is a hydrogen atom or a monovalent organic group. 2 is a single bond, an oxygen atom, or -NR 4 -R 4 is a hydrogen atom or a monovalent organic group. 2 , n1 and n2 are Y 1 and Y 2 at least one of Y is a fluorine atom or an alkyl group having 1 to 4 carbon atoms, or Y 1 and Y 2 are both hydrogen atoms, and A 1 and A 2 is an aromatic heterocyclic group, 2 represents an alkanediyl group having 1 to 10 carbon atoms, a fluoroalkanediyl group having 1 to 10 carbon atoms, a divalent aliphatic cyclic group, or a divalent aromatic cyclic group, n1 is 0 or 1, and n2 is 0 or 1. When the above conditions are not satisfied, R 2 is an alkanediyl group having 1 to 10 carbon atoms, n1 is 1, and n2 is 1. Z 1 is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or —NR 5 R 6 , a nitrile group, a substituted or unsubstituted alkynyl group, an acetyl group, a trifluoromethyl group, or a fluorine atom, and when the above conditions are not satisfied, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, -NR 5 R 6 R is a nitrile group, a substituted or unsubstituted alkynyl group, an acetyl group, a trifluoromethyl group, or a fluorine atom. 5 and R 6 are each independently an alkyl group having 1 to 16 carbon atoms.1 represents an alkanediyl group having 1 to 10 carbon atoms, or an alkanediyl group having 2 to 10 carbon atoms in which one or more methylene groups are -O-, -S-, or -NR 7 -, -CO-, -CO-O- or -CO-NR 7 - is a divalent group in which R 7 is a hydrogen atom or a monovalent organic group. "*" represents a bond. [ka] (In formula (4), A 3 and A 4 are each independently a nitrogen-containing aromatic heterocyclic group. 1 " represents a bond to an atom contained in the polymer main chain.)

[0009] [2] A method for producing a liquid crystal alignment film, comprising forming a weak anchoring liquid crystal alignment film using the liquid crystal aligning agent for forming a weak anchoring film according to [1] above. [3] A method for manufacturing a liquid crystal element comprising a pair of substrates consisting of a first substrate and a second substrate, and a liquid crystal layer disposed between the pair of substrates, comprising: A method for manufacturing a liquid crystal element, comprising a step of forming a weak anchoring liquid crystal alignment film by applying the liquid crystal alignment agent for forming a weak anchoring film described in [1] above to the surface of at least one of the first substrate and the second substrate and performing a photoalignment treatment.

[0010] [4] A method for manufacturing a liquid crystal device comprising a pair of substrates consisting of a first substrate and a second substrate, and a liquid crystal layer disposed between the pair of substrates, the method comprising the steps of: applying the liquid crystal alignment agent for forming a weak anchoring film described in [1] above to a surface of at least one of the first substrate and the second substrate, and performing a photo-alignment treatment to form a first liquid crystal alignment film; and forming a second liquid crystal alignment film on a surface of one of the first substrate and the second substrate, which is different from the substrate on which the first liquid crystal alignment film is formed, wherein the second liquid crystal alignment film contains a polymer having a partial structure represented by the following formula (5) in its main chain. [ka] (In formula (5), B 1 is a cyclic group. 2 and B 3 are each independently an aromatic ring group. "*" represents a bond to an atom contained in the polymer main chain.

[0011] [5] A method for manufacturing a liquid crystal device comprising a pair of substrates consisting of a first substrate and a second substrate, and a liquid crystal layer disposed between the pair of substrates, the method comprising: forming a first liquid crystal alignment film on a surface of one of the first substrate and the second substrate by a photo-alignment method; and forming a second liquid crystal alignment film on a surface of one of the first substrate and the second substrate, which is different from the substrate on which the first liquid crystal alignment film is formed, by a rubbing method, wherein in the step of forming the first liquid crystal alignment film, a heat treatment is not performed after exposure for the photo-alignment treatment, or a heat treatment is performed at a temperature of 200°C or less.

[0012] [6] A method for manufacturing a liquid crystal device comprising a pair of substrates consisting of a first substrate and a second substrate, and a liquid crystal layer disposed between the pair of substrates, the method comprising: forming a first liquid crystal alignment film on a surface of the first substrate by a photo-alignment method; and forming a second liquid crystal alignment film on a surface of the second substrate by a photo-alignment method; in the step of forming one of the first and second liquid crystal alignment films, a heat treatment is performed at a first temperature after exposure for the photo-alignment treatment; and in the step of forming the other liquid crystal alignment film, either no heat treatment is performed after exposure for the photo-alignment treatment, or a heat treatment is performed at a second temperature lower than the first temperature. [Effects of the Invention]

[0013] The liquid crystal aligning agent of the present invention can form a liquid crystal alignment film for obtaining a liquid crystal device that exhibits good liquid crystal alignment properties and alignment uniformity, and that can be driven at a low voltage while having high brightness. [Brief explanation of the drawings]

[0014] [Figure 1] Schematic diagram of an FFS type liquid crystal display element. [Figure 2] Schematic plan views of the top electrode used in the manufacture of a liquid crystal display element, where (a) is a top view of the top electrode and (b) is an enlarged partial view of the top electrode. [Figure 3] FIG. 1 shows four drive electrodes. DETAILED DESCRIPTION OF THE INVENTION

[0015] Matters related to the embodiments will be explained in detail below. In this specification, a numerical range described 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 of which are included in the main chain structure. A "structural unit" refers to a unit that mainly constitutes the main chain structure, and at least two or more of which are included in the main chain structure. A structural unit is typically a repeating unit formed from one monomer. A repeating unit having a reactive group that is reacted with a compound having a functional group that can react with the reactive group in the repeating unit is also included in the "structural unit".

[0016] 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 chain hydrocarbon 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 alicyclic hydrocarbon group does not necessarily have to be composed solely of an alicyclic hydrocarbon structure, and may also contain a chain structure as part of it. The term "aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as a ring structure. However, the aromatic hydrocarbon 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 it. 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).

[0017] The "main chain" of a polymer refers to the "trunk" portion of the polymer, which is made up of the longest chain of atoms. It is permissible for this "trunk" portion to contain a ring structure. For example, "having a specific structure in the main chain" means that the specific structure constitutes a part of the main chain. A "side chain" refers to a portion branched from the "trunk" portion of the polymer. "(Meth)acrylic" is a term that includes acrylic and methacrylic, and "(meth)acrylo" is a term that includes acrylo and methacrylo. "(Meth)acrylate" is a term that includes acrylate and methacrylate.

[0018] Liquid crystal alignment agent The liquid crystal aligning agent of the present disclosure is a liquid crystal aligning agent for forming a weak anchoring film, which is used to form a weak anchoring liquid crystal alignment film. "Weak anchoring" means that the alignment restraint force of liquid crystal molecules is substantially zero in the in-plane direction, and even if the horizontal alignment of the liquid crystal molecules is forced, the alignment restraint force in the in-plane direction is substantially zero. Specifically, weak anchoring means, for example, a state in which the azimuthal anchoring strength (A2) is 10 -4 This refers to the case where the azimuthal anchoring strength (A2) is smaller than 10 -5 In the state of weak anchoring (also called zero-plane anchoring), the in-plane orientation direction can be freely rotated 360° by control using an external field such as an electric field or a magnetic field.

[0019] In a typical liquid crystal element, the alignment of liquid crystal molecules is controlled by a pair of liquid crystal alignment films (strong anchoring liquid crystal alignment films). In contrast, the liquid crystal aligning agent of the present disclosure is a polymer composition for forming a weak anchoring liquid crystal alignment film in which the alignment restraining force of liquid crystal molecules is substantially zero in the in-plane direction. Here, to explain the "weak anchoring liquid crystal alignment film" and the "strong anchoring liquid crystal alignment film," the difference between the "weak anchoring liquid crystal alignment film" and the "strong anchoring liquid crystal alignment film" is that the alignment restraining force that restrains the alignment direction of liquid crystal molecules is different. That is, in a weak anchoring liquid crystal alignment film, the alignment restraining force of liquid crystal molecules is substantially zero in the in-plane direction, whereas a strong anchoring liquid crystal alignment film has stronger anchoring energy than a weak anchoring liquid crystal alignment film. A strong anchoring film has an azimuthal anchoring strength (A2) of 10 -4 It is preferable that it is greater than .

[0020] More specifically, in a liquid crystal cell, when the orientation of liquid crystal molecules near the alignment film is controlled by a strong anchoring liquid crystal alignment film, when an electric field is applied, the liquid crystal molecules at the interface between the liquid crystal layer and the liquid crystal alignment film maintain their alignment direction before the application of the electric field, while still subject to the alignment constraint force of the liquid crystal alignment film. In contrast, a weak anchoring liquid crystal alignment film has no or very weak alignment constraint force on the liquid crystal molecules at the interface between the liquid crystal layer and the liquid crystal alignment film, making the alignment direction of the liquid crystal molecules prone to change when an electric field is applied. Weak anchoring of the liquid crystal alignment film reduces the alignment constraint force on the liquid crystal molecules not only in the horizontal direction but also in the vertical direction. Therefore, a liquid crystal cell equipped with a weak anchoring liquid crystal alignment film is thought to be able to drive liquid crystal molecules at a lower voltage.

[0021] In a typical liquid crystal element, the alignment of liquid crystal molecules is controlled by a pair of liquid crystal alignment films (i.e., strong anchoring liquid crystal alignment films), but the alignment of liquid crystal molecules can also be controlled by combining a weak anchoring liquid crystal alignment film and a strong anchoring liquid crystal alignment film. For example, if a strong anchoring liquid crystal alignment film is formed on the first substrate (electrode substrate) side on which a pair of electrodes is provided, using a liquid crystal alignment agent for horizontal alignment, and a weak anchoring liquid crystal alignment film is formed on the second substrate (counter substrate) side, the liquid crystal molecules will be horizontally aligned throughout the entire liquid crystal layer when the liquid crystal element is not driven.

[0022] The liquid crystal aligning agent of the present disclosure contains a polymer (hereinafter also referred to as "polymer (P)") having at least one specific partial structure selected from the group consisting of a partial structure represented by the following formula (1), a partial structure represented by the following formula (2), a partial structure represented by the following formula (3), a partial structure represented by the following formula (4), an azobenzene structure, a chalcone structure, a coumarin structure, and a chromanone structure. Note that, hereinafter, the partial structure represented by the following formula (1), the partial structure represented by the following formula (2), and the partial structure represented by the following formula (3) are also referred to as a "cinnamate structure." [ka] (In formula (1), A 1 and A 2 are each independently an aromatic ring group. 1 and Y 2 are each independently a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 10 carbon atoms. 1 is an oxygen atom or -NR 3 -R 3 is a hydrogen atom or a monovalent organic group. n1 is an integer of 0 to 2. When n1 is 2, a plurality of A 1 are the same or different. 1 " represents a bond to an atom contained in the polymer main chain.) [ka] (In formula (2), A 1 and A 2are each independently an aromatic ring group. n1 is 0 or 1. Y 1 and Y 2 are each independently a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 10 carbon atoms. 1 is an oxygen atom or -NR 3 -R 3 is a hydrogen atom or a monovalent organic group. 2 is a single bond, an oxygen atom, or -NR 4 -R 4 is a hydrogen atom or a monovalent organic group. 2 represents an alkanediyl group having 1 to 10 carbon atoms, a fluoroalkanediyl group having 1 to 10 carbon atoms, a divalent aliphatic ring group, or a divalent aromatic ring group. n2 is 0 or 1. Z 1 represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, -NR 5 R 6 R is a nitrile group, a substituted or unsubstituted alkynyl group, an acetyl group, a trifluoromethyl group, or a fluorine atom. 5 and R 6 are each independently an alkyl group having 1 to 16 carbon atoms. 1 represents an alkanediyl group having 1 to 10 carbon atoms, or an alkanediyl group having 2 to 10 carbon atoms in which one or more methylene groups are -O-, -S-, or -NR 7 -, -CO-, -CO-O- or -CO-NR 7 - is a divalent group in which R 7 is a hydrogen atom or a monovalent organic group. "*" represents a bond. [ka] (In formula (3), A 1 and A 2 are each independently an aromatic ring group. 1 and Y 2 are each independently a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 10 carbon atoms. 1 is an oxygen atom or -NR 3 -R 3 is a hydrogen atom or a monovalent organic group. 2is a single bond, an oxygen atom, or -NR 4 -R 4 is a hydrogen atom or a monovalent organic group. 2 , n1 and n2 are Y 1 and Y 2 at least one of Y is a fluorine atom or an alkyl group having 1 to 4 carbon atoms, or Y 1 and Y 2 are both hydrogen atoms, and A 1 and A 2 is an aromatic heterocyclic group (this is referred to as condition A), 2 represents an alkanediyl group having 1 to 10 carbon atoms, a fluoroalkanediyl group having 1 to 10 carbon atoms, a divalent aliphatic cyclic group, or a divalent aromatic cyclic group, n1 is 0 or 1, and n2 is 0 or 1; if the above condition A is not satisfied, R 2 is an alkanediyl group having 1 to 10 carbon atoms, n1 is 1, and n2 is 1. Z 1 is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, -NR 5 R 6 , a nitrile group, a substituted or unsubstituted alkynyl group, an acetyl group, a trifluoromethyl group, or a fluorine atom, and when the above condition A is not satisfied, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, -NR 5 R 6 R is a nitrile group, a substituted or unsubstituted alkynyl group, an acetyl group, a trifluoromethyl group, or a fluorine atom. 5 and R 6 are each independently an alkyl group having 1 to 16 carbon atoms. 1 represents an alkanediyl group having 1 to 10 carbon atoms, or an alkanediyl group having 2 to 10 carbon atoms in which one or more methylene groups are -O-, -S-, or -NR 7 -, -CO-, -CO-O- or -CO-NR 7 - is a divalent group in which R 7 is a hydrogen atom or a monovalent organic group. "*" represents a bond. [ka] (In formula (4), A 3 and A 4 are each independently a nitrogen-containing aromatic heterocyclic group. 1 " represents a bond to an atom contained in the polymer main chain.)

[0023] The components contained in the liquid crystal aligning agent of the present disclosure will be described in detail below. Unless otherwise specified, each component may be used alone or in combination of two or more.

[0024] <Polymer (P)> (Cinnamate structure) Of the partial structures represented by the formulas (1) to (3), the partial structure represented by the formula (1) is introduced into the main chain of the polymer (P). The partial structures represented by the formulas (2) and (3) are introduced into the side chains of the polymer (P). By introducing these cinnamate structures into the polymer (P), photoalignment properties are imparted to the polymer (P).

[0025] In the above formulas (1) to (3), A 1 or A 2 The aromatic ring group represented by the formula (I) is a group in which two hydrogen atoms have been removed from the ring portion of a substituted or unsubstituted aromatic ring. Examples of the aromatic ring include aromatic hydrocarbon rings such as a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring; and aromatic heterocycles such as a pyridine ring, a pyrimidine ring, an imidazole ring, a thiophene ring, and a furan ring. Among these, a benzene ring or a naphthalene ring is preferred, and a benzene ring is more preferred, in that it can further increase the photoreactivity of the cinnamate structure.

[0026] A 1 or A 2 When the aromatic ring group represented by the formula (I) has a substituent on the ring portion, examples of the substituent include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.), a hydroxyl group, a carboxy group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and a cyano group.

[0027] Y1 or Y 2 The alkyl group having 1 to 10 carbon atoms represented by the formula (I) may be linear or branched. Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a sec-pentyl group, and an n-hexyl group. Y 1 or Y 2 Of these, the alkyl group having 1 to 10 carbon atoms represented by the following formula is preferably a linear or branched alkyl group having 1 to 4 carbon atoms, more preferably a methyl group or an ethyl group.

[0028] X 1 Ga-NR 3 -If R 3 Examples of the monovalent organic group represented by the formula (I) include monovalent hydrocarbon groups having 1 to 10 carbon atoms, monovalent leaving groups, etc. Among these, examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms include alkyl groups having 1 to 10 carbon atoms, alkenyl groups having 2 to 10 carbon atoms, alkynyl groups having 2 to 10 carbon atoms, cycloalkyl groups having 3 to 10 carbon atoms, alkylcycloalkyl groups having 4 to 10 carbon atoms, cycloalkylalkyl groups having 4 to 10 carbon atoms, phenyl groups, methylphenyl groups, and phenylmethyl groups.

[0029] R 3When is a monovalent leaving group, the monovalent leaving group is preferably a group that leaves by heat or light, and more preferably a group that leaves by heat (i.e., a thermally detachable group). Examples of thermally detachable groups include carbamate-based leaving groups, amide-based leaving groups, imide-based leaving groups, and sulfonamide-based leaving groups. Among these, carbamate-based leaving groups are preferred because of their high thermal detachability. Specific examples of carbamate-based leaving groups include a tert-butoxycarbonyl 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). Of these, the tert-butoxycarbonyl group (Boc group) is particularly preferred because it has excellent thermal desorption properties and can reduce the amount of deprotected portions remaining in the film.

[0030] X 2 Ga-NR 4 -If R 4 The monovalent organic group represented by R 3 Examples of the monovalent organic group represented by the following formula include the same groups as those exemplified above.

[0031] R 2 The alkanediyl group having 1 to 10 carbon atoms represented by the formula (I) may be linear or branched. Specific examples of the alkanediyl group include a methylene group, an ethylene group, a propane-1,3-diyl group, a propane-2,2-diyl group, a butane-1,4-diyl group, a butane-1,2-diyl group, a butane-1,3-diyl group, a butane-2,2-diyl group, a pentane-1,5-diyl group, and a hexane-1,6-diyl group. Examples of the fluoroalkanediyl group having 1 to 10 carbon atoms include groups in which any hydrogen atom in the above alkanediyl group having 1 to 10 carbon atoms has been replaced with a fluorine atom.

[0032] Examples of the divalent aliphatic cyclic group include a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms and a divalent aliphatic heterocyclic group having 4 to 20 carbon atoms. Specific examples of these include a cyclobutanediyl group, a cyclopentanediyl group, a cyclohexanediyl group, a cycloheptanediyl group, and a cyclooctanediyl group as divalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms. Examples of the divalent aliphatic heterocyclic group having 4 to 20 carbon atoms include a piperidinediyl group and a piperazinediyl group.

[0033] Examples of the divalent aromatic ring group include a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms and a divalent aromatic heterocyclic group having 4 to 20 carbon atoms. Specific examples of these include a phenylene group and a naphthalene group as aromatic hydrocarbon groups having 6 to 20 carbon atoms. Examples of the divalent aromatic heterocyclic group having 4 to 20 carbon atoms include a pyridinediyl group, a thiophenediyl group, and a furandiyl group.

[0034] Z 1 The alkyl group having 1 to 4 carbon atoms and the alkoxy group having 1 to 6 carbon atoms represented by the following formula are preferably linear. 1 Ga-NR 5 R 6 When R is a group represented by 5 , R 6 The alkyl group having 1 to 16 carbon atoms represented by the formula (I) is preferably linear. The substituted or unsubstituted alkynyl group includes an ethenyl group, a propenyl group, a butynyl group, and groups in which one or more hydrogen atoms in these groups have been replaced with a substituent. 1 or A 2 Examples of the substituent that the aromatic ring group represented by the following formula (I) may have include the same groups as those exemplified above. From the viewpoint of obtaining a liquid crystal element with better liquid crystal alignment, Z 1 represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, -NR 5 R 6 , a nitrile group, a substituted or unsubstituted alkynyl group, an acetyl group, a trifluoromethyl group, or a fluorine atom is preferred.

[0035] Z in the above formula (2) 1 When Y is a hydrogen atom, from the viewpoint of obtaining a liquid crystal device with better white luminance, 1 and Y 2 It is preferable that at least one of Z in the above formula (2) is a fluorine atom or an alkyl group having 1 to 4 carbon atoms. 1 When is a hydrogen atom, it is preferred that n2=1.

[0036] R 1 The alkanediyl group having 1 to 10 carbon atoms represented by R 2 Examples of the alkanediyl group include the same groups as those exemplified as the alkanediyl group having 1 to 10 carbon atoms and represented by the following formula: Of these, the linear one is preferred. R 1 is an alkanediyl group having 2 to 10 carbon atoms in which one or more methylene groups are -O-, -S-, or -NR 7 -, -CO-, -CO-O- or -CO-NR 7 In this case, R 7 The monovalent organic group represented by R 3 Examples of the monovalent organic group represented by the following formula include the same groups as those exemplified above.

[0037] However, R in the above formula (3) 2 , n1 and n2 satisfy the following condition A. 2 represents an alkanediyl group having 1 to 10 carbon atoms, a fluoroalkanediyl group having 1 to 10 carbon atoms, a divalent aliphatic ring group, or a divalent aromatic ring group, n1 is 0 or 1, and n2 is 0 or 1. In addition, when the following condition A is not satisfied, R 2 is an alkanediyl group having 1 to 10 carbon atoms, n1 is 1, and n2 is 1. When the following condition A is satisfied, R 3 does not become a hydrogen atom. <Condition A>Y 1 and Y 2 at least one of Y is a fluorine atom or an alkyl group having 1 to 4 carbon atoms, or Y 1 and Y 2are both hydrogen atoms, and A 1 and A 2 At least one of the groups is an aromatic heterocyclic group.

[0038] Specific examples of the partial structure represented by the above formula (1) include partial structures represented by the following formulas. [ka] (In the formula, "*" represents a bond.)

[0039] Specific examples of the partial structure represented by the above formula (2) include partial structures represented by the following formulas. [ka] (In the formula, "*" represents a bond.)

[0040] Specific examples of the partial structure represented by the above formula (3) include partial structures represented by the following formulas. [ka] (In the formula, "*" represents a bond.)

[0041] The partial structure represented by the above formula (3) is advantageous in that it can provide a liquid crystal device with superior white luminance. 1 and Y 2 It is preferable that at least one of Y is a group other than a hydrogen atom. 1 and Y 2 and are more preferably groups other than a hydrogen atom. A 1 is preferably an aromatic heterocyclic group.

[0042] The cinnamate structure of the polymer (P) is preferably the partial structure represented by the above formula (1) or the partial structure represented by the above formula (2), since a liquid crystal device with more excellent white luminance can be obtained.

[0043] (Partial structure represented by formula (4)) The partial structure represented by the above formula (4) is introduced into the main chain of the polymer (P), thereby imparting photoalignment properties to the polymer (P).

[0044] In the above formula (4), A 3 or A 4 The nitrogen-containing aromatic heterocyclic group represented by the formula (I) is a divalent group obtained by removing two hydrogen atoms from the ring portion of a substituted or unsubstituted nitrogen-containing aromatic heterocycle. In the divalent group, examples of the nitrogen-containing aromatic heterocycle include a pyridine ring, a pyrimidine ring, a pyrazine ring, a pyridazine ring, a triazine ring, an imidazole ring, and a benzimidazole ring. Of these, a pyridine ring or a pyrimidine ring is preferred. A 3 or A 4 The substituents that the nitrogen-containing aromatic heterocyclic group represented by the formula (I) may have include: 1 or A 2 Examples of the substituent that the aromatic ring group represented by the following formula (I) may have include the same groups as those exemplified above.

[0045] Specific examples of the partial structure represented by the above formula (4) include partial structures represented by the following formulas (4-1) to (4-4). [ka] (Formula (4-1) to formula (4-4), "* 1 " represents a bond to an atom contained in the polymer main chain.)

[0046] (Azobenzene structure, chalcone structure, coumarin structure, chromanone structure) The azobenzene structure, chalcone structure, coumarin structure and chromanone structure each have a structure represented by the following formula: These structures may be introduced into the main chain or side chain of the polymer (P). [ka]

[0047] (Main chain structure) The polymer (P) may have any of the specific partial structures described above, and its main skeleton is not particularly limited. Examples of the main skeleton of the polymer (P) include polymers having a polyamic acid, polyamic acid ester, polyimide, polyamine, polyenamine, polyamide, polyamideimide, polyurea, polyimine, polyorganosiloxane, or addition polymer 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.

[0048] From the viewpoints of obtaining a liquid crystal device with excellent liquid crystal alignment properties and voltage retention characteristics and of ease of introducing a specific partial structure, the polymer (P) is preferably at least one selected from the group consisting of addition polymers, polyamic acids, polyamic acid esters, polyimides, and polyorganosiloxanes. Each polymer will be described in detail below.

[0049] (addition polymer) Examples of the addition polymer as polymer (P) (hereinafter also referred to as "addition polymer (P)") include (meth)acrylic polymers, styrene polymers, maleimide polymers, (meth)acrylic-styrene copolymers, (meth)acrylic-maleimide copolymers, (meth)acrylic-styrene-maleimide copolymers, and styrene-maleimide copolymers. From the viewpoint of ease of synthesis, the addition polymer (P) preferably has a specific partial structure in a side chain of the polymer, and more preferably has a structural unit derived from a monomer having the specific partial structure.

[0050] Examples of the monomer having a specific partial structure include compounds represented by the following formulas. [ka]

[0051] In synthesizing the addition polymer (P), a monomer having no specific partial structure (hereinafter also referred to as "other monomer") may be used together with the monomer having the specific partial structure. Examples of the other monomer include a (meth)acrylic compound, a styrene compound, a conjugated diene compound, and a maleimide compound.

[0052] Specific examples of other monomers include (meth)acrylic compounds such as unsaturated carboxylic acids such as (meth)acrylic acid; alkyl (meth)acrylates (for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc.); cycloalkyl (meth)acrylates (for example, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, cyclooctyl (meth)acrylate, cyclodecane (meth)acrylate, cyclododecane (meth)acrylate, cyclotridecane (meth)acrylate, cyclotetradecane (meth)acrylate, etc. ), benzyl (meth)acrylate, trimethoxysilylpropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxybutyl (meth)acrylate, 4-hydroxybutyl glycidyl ether (meth)acrylate, 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, 6-(meth)acryloyloxyhexyltrimethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane.

[0053] Examples of aromatic vinyl compounds include styrene, methylstyrene, divinylbenzene, 4-hydroxymethylstyrene, p-styryltrimethoxysilane, 4-(glycidyloxymethyl)styrene, and vinylbenzoic acid. Examples of conjugated diene compounds include 1,3-butadiene and 2-methyl-1,3-butadiene. Examples of maleimide compounds include N-methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-(4-glycidyloxyphenyl)maleimide, N-(4-glycidyloxymethylphenyl)maleimide, N-glycidylmaleimide, N-(4-carboxyphenyl)maleimide, and N-(4-tert-butoxycarbonylphenyl)maleimide.

[0054] In the addition polymer (P), the proportion of the structural units having the specific partial structure is preferably 20 mol % or more, more preferably 30 mol % or more, and even more preferably 40 mol % or more, based on the total amount of structural units constituting the addition polymer (P), from the viewpoint of obtaining a liquid crystal device that exhibits excellent liquid crystal alignment while sufficiently achieving low-voltage drive. Also, in the addition polymer (P), the proportion of the structural units having the specific partial structure is preferably 95 mol % or less, more preferably 90 mol % or less, based on the total amount of structural units constituting the addition polymer (P), from the viewpoint of sufficiently achieving low-voltage drive.

[0055] In order to enhance the effect of improving the low-voltage driving of liquid crystal elements, the addition polymer (P) preferably contains structural units derived from a (meth)acrylic compound. In the addition polymer (P), the proportion of structural units derived from a (meth)acrylic compound is preferably 5 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 constituting the addition polymer (P).

[0056] The addition polymer (P) can be obtained, for example, by polymerizing the monomers in the presence of a polymerization initiator. The polymerization initiator used is preferably an azo compound such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), or 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile). The polymerization initiator is preferably used in an amount of 0.01 to 30 parts by mass relative to 100 parts by mass of the total monomers used in the reaction.

[0057] The polymerization reaction is preferably carried out in an organic solvent. Examples of organic solvents used in the reaction include alcohols, ethers, ketones, amides, esters, and hydrocarbon compounds, with diethylene glycol ethyl methyl ether and propylene glycol monomethyl ether acetate being preferred. The reaction temperature is preferably 30°C to 120°C, and the reaction time is preferably 1 to 36 hours. The amount of organic solvent used is preferably such that the total amount of monomers used in the reaction is 0.1 to 60% by mass relative to the total amount of the reaction solution. The addition polymer (P) can also be obtained by synthesizing an addition polymer having epoxy groups in its side chains, and then reacting the resulting epoxy-group-containing addition polymer with a carboxylic acid having an aliphatic ring with seven or more ring members (hereinafter also referred to as a "specific carboxylic acid").

[0058] The addition polymer (P) preferably has a weight average molecular weight (Mw) in terms of polystyrene measured by GPC of 250 to 500,000, more preferably 500 to 100,000. The molecular weight distribution (Mw / Mn), which is the ratio of Mw to the number average molecular weight (Mn) in terms of polystyrene measured by GPC, is preferably 8 or less, more preferably 6 or less.

[0059] (Polyamic acid) The polyamic acid as the polymer (P) (hereinafter also referred to as "polyamic acid (P)") can be obtained, for example, by reacting a tetracarboxylic dianhydride with a diamine compound.

[0060] Specifically, polyamic acids (P) having a cinnamate structure are preferably obtained by reacting a tetracarboxylic dianhydride with a diamine compound containing a diamine having a cinnamate structure, because this allows for a high degree of freedom in the selection of monomers. Polyamic acids (P) having the partial structure represented by formula (4) can be obtained by reacting a tetracarboxylic dianhydride containing 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride with a diamine compound containing a diamine having a partial structure in which a primary amino group is bonded to a nitrogen-containing aromatic heterocycle. Polyamic acids (P) having an azobenzene structure, chalcone structure, coumarin structure, or chromanone structure can be obtained by reacting a tetracarboxylic dianhydride with a diamine compound containing a diamine having an azobenzene structure, chalcone structure, coumarin structure, or chromanone structure.

[0061] Tetracarboxylic acid dianhydride Examples of the tetracarboxylic acid dianhydride used in the synthesis of the polyamic acid (P) include aliphatic tetracarboxylic acid dianhydrides and aromatic tetracarboxylic acid dianhydrides. The aliphatic tetracarboxylic acid dianhydrides include chain tetracarboxylic acid dianhydrides and alicyclic tetracarboxylic acid dianhydrides.

[0062] Specific examples of the chain tetracarboxylic dianhydride include butane tetracarboxylic dianhydride, etc. Specific examples of the alicyclic tetracarboxylic dianhydride include 1,2,3,4-cyclobutane tetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutane tetracarboxylic 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[4-(2-methyl-2-methyl-1 ... Bicyclo[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 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, ethylenediaminetetraacetic dianhydride, cyclopentanetetracarboxylic dianhydride, and the like.

[0063] Examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, p-phenylene bis(trimellitic 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, etc. In addition to the above, the tetracarboxylic dianhydrides described in JP 2010-97188 A can also be used as the tetracarboxylic dianhydride used in the synthesis of the polyamic acid (P).

[0064] Diamine compounds In synthesizing the polyamic acid (P), a diamine having a specific partial structure can be preferably used because it allows for a high degree of freedom in the selection of monomers. When obtaining the polyamic acid (P) having the partial structure represented by the above formula (4), a diamine having a partial structure in which a primary amino group is bonded to a nitrogen-containing aromatic heterocycle is used.

[0065] Examples of diamines having a specific partial structure include diamines represented by the following formulas. [ka]

[0066] Specific examples of diamines having a partial structure in which a primary amino group is bonded to a nitrogen-containing aromatic heterocycle include diamines represented by the following formulas (N-1) to (N-9), in which "Boc" represents a tert-butoxycarbonyl group (the same applies hereinafter). [ka]

[0067] When synthesizing the polyamic acid (P), diamines other than the above-mentioned diamines (hereinafter also referred to as "other diamines") may be used in combination. Examples of other diamines include aliphatic diamines, aromatic diamines, and diaminoorganosiloxanes. Aliphatic diamines include chain diamines and alicyclic diamines.

[0068] Specific examples of other diamines include chain diamines such as m-xylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 1,3-bis(aminomethyl)cyclohexane, etc., and alicyclic diamines such as 1,4-diaminocyclohexane and 4,4'-methylenebis(cyclohexylamine).

[0069] Examples of aromatic diamines include dodecanoxydiaminobenzene, tetradecanoxydiaminobenzene, pentadecanoxydiaminobenzene, hexadecanoxydiaminobenzene, octadecanoxydiaminobenzene, cholestanyloxydiaminobenzene, cholesteryloxydiaminobenzene, cholestanyl diaminobenzoate, cholesteryl diaminobenzoate, lanostannyl diaminobenzoate, 3,6-bis(4-aminobenzoyloxy)cholestane, 3,6-bis(4-aminophenoxy)cholestane, 1 ,1-bis(4-((aminophenyl)methyl)phenyl)-4-butylcyclohexane, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-heptylcyclohexane, 1,1-bis(4-((aminophenoxy)methyl)phenyl)-4-heptylcyclohexane, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-(4-heptylcyclohexyl)cyclohexane, N-(2,4-diaminophenyl)-4-(4-heptylcyclohexyl)benzamide, the following formula (E-1): [ka] (In formula (E-1), X I and X IIare each independently a single bond, -O-, *-COO-, or *-OCO- (where * represents a 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. Directing group-containing diamines such as compounds represented by the formula: Paraphenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylamine, 4,4'-diaminodiphenyl sulfide, 4-aminophenyl-4'-aminobenzoate, 4,4'-diaminoazobenzene, 1,2-bis(4-aminophenoxy)ethane, 1,3-bis(4-aminophenoxy)propane, 1,5-bis(4-aminophenoxy)pentane, 1,6-bis(4-aminophenoxy)hexane, 1,7-bis(4- aminophenoxy)heptane, bis[2-(4-aminophenyl)ethyl]hexanedioic acid, N,N-bis(4-aminophenyl)methylamine, 4,4'-(2,2'-oxybis(ethane-2,1-diyl)bis(oxy))dianiline, 1,5-diaminonaphthalene, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl ether, 2,2-bis[ 4-(4-aminophenoxy)phenyl]propane, 9,9-bis(4-aminophenyl)fluorene, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-(p-phenylenediisopropylidene)bisaniline, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, N,N'-bis(4-aminophen N,N'-bis(4-aminophenyl)-N,N'-dimethylbenzidine, 1,4-bis-(4-aminophenyl)-piperazine, 3,5-diaminobenzoic acid, methyl 3,5-diaminobenzoate, ethyl 3,5-diaminobenzoate, 1-(4-aminophenoxy)-2-(4-(4'-aminophenyl)phenoxy)ethane, 3,5-diamino-N,N-bis(pyridin-3-ylmethyl)benzamide, compounds represented by the following formulas (f-1) to (f-27): [ka] [ka] Diamines represented by the following formula: Examples of diaminoorganosiloxanes include 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, and the diamines described in JP-A-2010-97188 can also be used.

[0070] In the above formula (E-1), "-X I -(R I -X II ) d The divalent group represented by "-" is preferably an alkanediyl group having 1 to 3 carbon atoms, *-O-, *-COO-, or *-O-C2H4-O- (wherein the bond marked with "*" is bonded to a diaminophenyl group). III The group represented by the formula (I) is preferably linear. The two amino groups in the diaminophenyl group are preferably in the 2,4-position or the 3,5-position relative to the other group.

[0071] Specific examples of the compound represented by the above formula (E-1) include compounds represented by the following formulas (E-1-1) to (E-1-4). [ka]

[0072] The content of the specific partial structure in the polyamic acid (P) is preferably 5 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 compound constituting the polyamic acid (P). By setting the content of the specific partial structure within the above range, it is possible to obtain a liquid crystal element with excellent liquid crystal alignment properties while realizing low-voltage operation of the liquid crystal element.

[0073] Synthesis of polyamic acid The polyamic acid (P) can be obtained by reacting the above-mentioned 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, and more preferably 0.3 to 1.2 equivalents, of the acid anhydride group of the tetracarboxylic dianhydride are used per equivalent of the amino group of the diamine compound.

[0074] 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, and more preferably 10 parts by mass or less, per 100 parts by mass of the total of the tetracarboxylic dianhydride and diamine compounds used.

[0075] The synthesis reaction of the polyamic acid (P) is preferably carried out in an organic solvent. The reaction temperature is preferably −20° C. to 150° C., more preferably 0 to 100° C. The reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours.

[0076] Examples of organic solvents used in the reaction include aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons. Among these organic solvents, it is preferable to use one or more selected from the group consisting of aprotic polar solvents and phenolic solvents (Group 1 organic solvents), or a mixture of one or more selected from Group 1 organic solvents with one or more selected from the group consisting of alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons (Group 2 organic solvents). In the latter case, the proportion of the Group 2 organic solvent used is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, based on the total amount of the Group 1 organic solvents and the Group 2 organic solvents.

[0077] Particularly preferred organic solvents are 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, or a mixture of one or more of these with other organic solvents in the above-mentioned proportions. The amount (x) of the organic solvent used is preferably an amount such that the total amount (y) of the tetracarboxylic dianhydride and the diamine compound is 0.1 to 50 mass% relative to the total amount (x+y) of the reaction solution.

[0078] 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.

[0079] (Polyamic acid ester) The polyamic acid ester as the polymer (P) can be obtained, for example, by [I] a method of reacting the polyamic acid (P) obtained by the above synthesis reaction with an esterifying agent, [II] a method of reacting a tetracarboxylic acid diester with a diamine compound, or [III] a method of reacting a tetracarboxylic acid diester dihalide with a diamine compound.

[0080] 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.

[0081] 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, propanol, etc.), and phenols (e.g., phenol, cresol, etc.); acetal compounds such as N,N-dimethylformamide diethyl acetal, N,N-diethylformamide diethyl acetal; halides such as methyl bromide, ethyl bromide, stearyl bromide, methyl chloride, stearyl chloride, 1,1,1-trifluoro-2-iodoethane, etc.; and epoxy group-containing compounds such as propylene oxide, etc.

[0082] The tetracarboxylic acid diester used in Method [II] can be obtained, for example, by ring-opening the tetracarboxylic acid dianhydride exemplified in the description of the synthesis of polyamic acid (P) using an alcohol such as methanol or ethanol. Note that in Method [II], a tetracarboxylic acid dianhydride may be used in combination. Regarding the diamine compound, the specific diamine exemplified in the synthesis of polyamic acid may be used alone, or may be used in combination with other diamines.

[0083] The reaction of method [II] is preferably carried out in an organic solvent in the presence of a suitable dehydration catalyst. Examples of the organic solvent include those exemplified as those used in the synthesis of polyamic acid (P). Examples of the dehydration catalyst include 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium halide, carbonylimidazole, and phosphorus-based condensing agents. The reaction temperature is preferably −20 to 150° C., more preferably 0 to 100° C. The reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours.

[0084] The tetracarboxylic acid diester dihalide used in Method [III] can be obtained, for example, by reacting the tetracarboxylic acid diester obtained as described above with a suitable chlorinating agent such as thionyl chloride. Note that a tetracarboxylic acid dianhydride may also be used in Method [III]. Regarding the diamine compound, the specific diamines exemplified in the description of the synthesis of polyamic acid (P) may be used alone or in combination with other diamines.

[0085] The reaction in method [III] is preferably carried out in an organic solvent in the presence of a suitable base. Examples of the organic solvent include those exemplified as those used in the synthesis of polyamic acid (P). Examples of the base that can be preferably used include tertiary amines such as pyridine and triethylamine; and alkali metals such as sodium hydride, potassium hydride, sodium hydroxide, potassium hydroxide, sodium, and potassium. The reaction temperature is preferably −20 to 150° C., more preferably 0 to 100° C. The reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours.

[0086] The polyamic acid ester 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 is dissolved may be used for preparing the liquid crystal aligning agent as is, or the polyamic acid ester contained in the reaction solution may be isolated and then used for preparing the liquid crystal aligning agent, or the isolated polyamic acid ester may be purified and then used for preparing the liquid crystal aligning agent. The isolation and purification of the polyamic acid ester may be carried out according to a known method.

[0087] (Polyimide) The polyimide as the polymer (P) can be obtained, for example, by dehydrating and cyclizing the polyamic acid (P) synthesized as described above to form an imidized polymer.

[0088] The polyimide may be a fully imidized product in which all amic acid structures contained in its precursor polyamic acid 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 used in the reaction preferably has an imidization rate of 10% or more, more preferably 20 to 99%, and even more preferably 20 to 95%. This imidization rate is the ratio, expressed as a percentage, of the number of imide ring structures to the total number of amic acid structures and imide ring structures in the polyimide. Here, some of the imide rings may be isoimide rings.

[0089] The dehydration ring-closure of the polyamic acid is preferably carried out by heating the polyamic acid, or by dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydration ring-closure catalyst to the solution, and optionally heating the solution.

[0090] In the method of adding a dehydrating agent and a dehydration ring-closing catalyst to a solution of polyamic acid, 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. 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. 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.

[0091] In this way, a reaction solution containing a polyimide 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 the polyimide, or may be used for the preparation of a liquid crystal aligning agent after purifying the isolated polyimide. These purification operations can be performed according to known methods. Alternatively, polyimide can also be obtained by imidizing a polyamic acid ester.

[0092] The polyamic acid, polyamic acid ester, and polyimide as polymer (P) obtained as described above preferably have a solution viscosity of 20 to 1,800 mPa·s, and more preferably 50 to 1,500 mPa·s, when made into a 15% by mass solution. The solution viscosity (mPa·s) of the polymer is a value measured at 25°C using an E-type rotational viscometer for a 15% by mass polymer solution prepared using a good solvent for the polymer (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

[0093] The polystyrene-equivalent weight average molecular weight (Mw) of the polyamic acid, polyamic acid ester, and polyimide as polymer (P), measured by gel permeation chromatography (GPC), is preferably 1,000 to 500,000, and more preferably 2,000 to 300,000. Furthermore, the molecular weight distribution (Mw / Mn), expressed as the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) measured by GPC, of ​​the polyamic acid, polyamic acid ester, and polyimide as polymer (P) is preferably 8 or less, and more preferably 5 or less. When the Mw and Mw / Mn of the polyamic acid, polyamic acid ester, and polyimide as polymer (P) are within the above ranges, good liquid crystal alignment properties of the liquid crystal device can be ensured.

[0094] (Polyorganosiloxane) The polyorganosiloxane as the polymer (P) (hereinafter also referred to as "polyorganosiloxane (P)") may be produced by any method as long as it produces a polymer having a specific partial structure. Specific examples include the following methods [1s] and [2s].

[0095] [1s] A method in which a hydrolyzable silane compound (ms-1) having an epoxy group, or a mixture of the silane compound (ms-1) and another silane compound, is hydrolyzed and condensed to synthesize an epoxy group-containing polyorganosiloxane, and then the obtained epoxy group-containing polyorganosiloxane is reacted with a carboxylic acid having a specific partial structure. [2s] A method of hydrolyzing and condensing a hydrolyzable silane compound (ms-2) having a specific partial structure, or a mixture of the silane compound (ms-2) and another silane compound. Among these, the method [1s] is preferable because it is simple and easy and can increase the introduction rate of the specific partial structure into the polyorganosiloxane (P).

[0096] Specific examples of the silane compound (ms-1) include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethylmethyldimethoxysilane, 2-glycidoxyethyldimethylmethoxysilane, 2-glycidoxyethyldimethylethoxysilane, 4-glycidoxybutyltrimethoxysilane, 4-glycidoxybutylmethyldimethoxysilane, 4-glycidoxybutylmethyldiethoxysilane, 4-glycidoxybutyldimethylmethoxysilane, 4-glycidoxybutyldimethylethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, and 3-(3,4-epoxycyclohexyl)propyltrimethoxysilane.

[0097] The other silane compounds used in the synthesis of the epoxy group-containing polyorganosiloxane are not particularly limited as long as they are hydrolyzable silane compounds, and specific examples thereof include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane, and dimethyldiethoxysilane; Nitrogen- and sulfur-containing alkoxysilanes, such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, mercaptomethyltrimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(3-cyclohexylamino)propyltrimethoxysilane, and N-2-(aminoethyl)-3-aminopropyltrimethoxysilane; Examples of the alkoxysilane include unsaturated hydrocarbon-containing alkoxysilanes such as 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, 6-(meth)acryloyloxyhexyltrimethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and p-styryltrimethoxysilane; and trimethoxysilylpropylsuccinic anhydride.

[0098] The hydrolysis and condensation reaction of silane compounds can be carried out by reacting one or more of the above silane compounds with water, preferably in the presence of a suitable catalyst and organic solvent. The proportion of water used in the reaction is preferably 1 to 30 moles per mole of the total amount of silane compounds. Examples of catalysts include acids, alkali metal compounds, organic bases, titanium compounds, and zirconium compounds. The amount of catalyst used varies depending on the type of catalyst, reaction conditions such as temperature, and can be appropriately determined. The amount of catalyst used is preferably 0.01 to 3 moles per total amount of silane compounds. Examples of organic solvents used include hydrocarbons, ketones, esters, ethers, and alcohols. Among these, it is preferable to use a water-insoluble or slightly water-soluble organic solvent. The proportion of organic solvent used is preferably 10 to 10,000 parts by mass per 100 parts by mass of the total amount of silane compounds used in the reaction.

[0099] The hydrolysis-condensation reaction is preferably carried out by heating, for example, in an oil bath. The heating temperature is preferably 130°C or lower, and the heating time is preferably 0.5 to 12 hours. After the reaction is complete, the organic solvent layer separated from the reaction solution is dried with a desiccant, if necessary, and the solvent is then removed to obtain the desired polyorganosiloxane. The synthesis of polyorganosiloxane is not limited to the hydrolysis-condensation reaction described above; for example, it may be carried out by reacting a hydrolyzable silane compound in the presence of oxalic acid and an alcohol.

[0100] In the method [1s], the epoxy group-containing polyorganosiloxane obtained by the above reaction is then reacted with a carboxylic acid having a specific partial structure, whereby the epoxy group of the epoxy group-containing polyorganosiloxane reacts with the carboxy group of the carboxylic acid of the specific partial structure to obtain a polyorganosiloxane (P) having the specific partial structure in its side chain.

[0101] As the carboxylic acid having the specific partial structure, a carboxylic acid having a cinnamate structure can be preferably used. Specific examples of the carboxylic acid having the specific partial structure include compounds represented by the following formulas: [ka]

[0102] The content of the specific partial structure in one molecule of polyorganosiloxane (P) is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more, based on the silicon atoms of polyorganosiloxane (P). Furthermore, the content of the specific partial structure in one molecule of polyorganosiloxane (P) is preferably 70 mol% or less, more preferably 60 mol% or less, based on the silicon atoms of polyorganosiloxane (P). By ensuring that the content of the specific partial structure in polyorganosiloxane (P) is within the above range, a liquid crystal device with excellent liquid crystal alignment properties can be obtained while still achieving sufficient low-voltage operation of the liquid crystal device.

[0103] In the synthesis of polyorganosiloxane (P), the carboxylic acid used in the reaction with the epoxy group-containing polyorganosiloxane may be only a carboxylic acid having the specific partial structure, or a carboxylic acid not having the specific partial structure (hereinafter also referred to as "other carboxylic acid") may be used in combination. Examples of other carboxylic acids include alkyl groups having 1 to 30 carbon atoms, halogenated alkyl groups having 1 to 30 carbon atoms, alkoxy groups having 1 to 30 carbon atoms, halogenated alkoxy groups having 1 to 30 carbon atoms, or carboxylic acids having a group having a polymerizable carbon-carbon unsaturated bond, other than the above compounds.

[0104] The reaction of the epoxy group-containing polyorganosiloxane with the carboxylic acid can be preferably carried out in the presence of a catalyst and an organic solvent. Examples of the catalyst include organic bases and compounds known as curing accelerators (e.g., tertiary organic amines, quaternary organic amines, quaternary ammonium salts, etc.) that accelerate the reaction of epoxy compounds. The amount of catalyst used is preferably 100 parts by mass or less, more preferably 0.1 to 20 parts by mass, per 100 parts by mass of the epoxy group-containing polyorganosiloxane.

[0105] Examples of organic solvents used in the above reaction include hydrocarbons, ethers, esters, ketones, amides, and alcohols. The organic solvent is preferably used in a proportion such that the solids concentration (the proportion of the total mass of components other than the solvent in the reaction solution to the total mass of the solution) is 0.1% by mass or more, and more preferably 5 to 50% by mass. In the above reaction, the reaction temperature is preferably 0 to 200°C, more preferably 50 to 150°C. The reaction time is preferably 0.1 to 50 hours, more preferably 0.5 to 20 hours. After completion of the reaction, it is preferable to wash the organic solvent layer separated from the reaction solution with water. After washing with water, the organic solvent layer is dried with an appropriate desiccant, if necessary, and the solvent is then removed to obtain the target polyorganosiloxane (P).

[0106] The polyorganosiloxane (P) preferably has a solution viscosity of 1 to 500 mPa·s, and more preferably 3 to 200 mPa·s, when prepared into a 10% by mass solution. The polyorganosiloxane (P) preferably has a weight average molecular weight (Mw) in terms of polystyrene, measured by GPC, of ​​1,000 to 200,000, more preferably 2,000 to 50,000, and even more preferably 3,000 to 20,000.

[0107] The content of the polymer (P) in the liquid crystal aligning agent of the present disclosure is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, relative to 100 parts by mass of the total of the polymer components contained in the liquid crystal aligning agent.

[0108] In addition, the content of the polymer (P) in the liquid crystal aligning agent of the present disclosure is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 30 parts by mass or more, relative to 100 parts by mass of the solid content (components other than the solvent of the liquid crystal aligning agent) contained in the liquid crystal aligning agent.

[0109] <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, an adhesion aid, a solvent, etc.

[0110] 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.

[0111] Among these, polymer (Q) is preferably at least one selected from the group consisting of addition polymers, polyamic acids, polyamic acid esters, polyimides, and polyorganosiloxanes, as they exhibit good liquid crystal alignment properties and voltage retention characteristics when used in combination with polymer (P). Specific examples of these include polymers obtained using monomers that do not have a specific partial structure among the examples of monomers that may constitute polymer (P). Furthermore, when polyorganosiloxane is used as polymer (Q), epoxy group-containing polyorganosiloxanes may be used, or reaction products of epoxy group-containing polyorganosiloxanes and other carboxylic acids may also be used.

[0112] The polymer (Q) preferably contains a polymer (Q1) having at least one of an alkyl group having 5 or more carbon atoms and a cycloalkyl group having 7 or more carbon atoms in its side chain, from the viewpoint of being able to obtain a liquid crystal alignment film that exhibits good weak anchoring properties and further improving the effect of low-voltage driving of liquid crystal elements. An addition polymer or polyorganosiloxane can be preferably used as the polymer (Q1), from the viewpoint of facilitating the introduction of at least one of an alkyl group having 5 or more carbon atoms and a cycloalkyl group having 7 or more carbon atoms into the side chain of the polymer.

[0113] In the polymer (Q1), the alkyl group having 5 or more carbon atoms may be linear or branched. A linear alkyl group is preferred because it can further enhance the weak anchoring property. The alkyl group preferably has 5 to 30 carbon atoms, more preferably 6 to 25 carbon atoms.

[0114] Examples of cycloalkyl groups having 7 or more carbon atoms include cycloheptane, cyclooctane, cyclononane, cyclodecane, cycloundecane, cyclododecane, cyclotridecane, cyclotetradecane, cyclopentadecane, cyclohexadecane, cycloheptadecane, cyclooctadecane, cyclononadecane, cycloicosane, cyclodocosane, etc. The number of carbon atoms in the cycloalkyl group is preferably 7 to 25, and more preferably 8 to 22.

[0115] The polymer (Q) may further contain, in addition to the polymer (Q1), a polymer different from the polymer (Q1) (hereinafter also referred to as "polymer (Q2)"). The liquid crystal aligning agent of the present disclosure may be a multi-component system containing the polymer (P), the polymer (Q1), and the polymer (Q2) as polymer components, thereby enhancing the mechanical and electrical properties of the liquid crystal alignment film. Examples of the polymer (Q2) include polymers obtained using a monomer that does not have a specific partial structure among the examples of the monomers that may constitute the polymer (P). Furthermore, when a polyorganosiloxane is used as the polymer (Q2), an epoxy group-containing polyorganosiloxane may be used, or a reaction product of an epoxy group-containing polyorganosiloxane and another carboxylic acid that does not have either an alkyl group having 5 or more carbon atoms or a cycloalkyl group having 7 or more carbon atoms may be used.

[0116] When the polymer (Q) is contained in the liquid crystal aligning agent, the content of the polymer (Q) is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the total amount of the polymer (P) and the polymer (Q). The content of the polymer (Q) is preferably 98 parts by mass or less, more preferably 95 parts by mass or less, and even more preferably 90 parts by mass or less, per 100 parts by mass of the total amount of the polymer (P) and the polymer (Q).

[0117] Crosslinking agent The liquid crystal aligning agent of the present disclosure may contain a crosslinking agent together with the polymer (P). By further containing a crosslinking agent in the liquid crystal aligning agent of the present disclosure, it is possible to obtain a liquid crystal element having excellent liquid crystal alignment properties (particularly AC afterimage characteristics) while achieving low-voltage driving of the liquid crystal element.

[0118] Examples of the crosslinking agent include compounds (excluding the polymer (P)) having, in one molecule, two or more of at least one type of crosslinkable group selected from the group consisting of an oxiranyl group, a protected oxiranyl group, an oxetanyl group, a thiol group, a protected thiol group, a carboxy group, a protected carboxy group, an acid anhydride group, a hydroxy group, a protected hydroxy group, an amino group, a protected amino group, a protected isocyanate group, and a group having a polymerizable carbon-carbon bond.

[0119] From the viewpoint of obtaining a liquid crystal alignment film that exhibits good weak anchoring properties and is excellent in liquid crystal alignment, 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 600.

[0120] Specific examples of the crosslinking agent include compounds having an oxiranyl group, a protected oxiranyl group, or an oxetanyl 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, trimethylolpropane triglycidyl ether, bisphenol A diglycidyl 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, epoxidation reaction products of 2,2'-diallylbisphenol A diallyl ether with hydrogen peroxide, and compounds represented by the following formulas (d1-1) and (d1-2).

[0121] Examples of compounds having a thiol group or a protected thiol group include 1,2-ethanedithiol, 1,3-propanedithiol, 1,3,4-thiadiazole-2,5-dithiol, 1,10-decanedithiol, pentaerythritol tetrakis(3-mercaptobutyrate), and 1,3,5-tris(2-(3-sulfanylbutanoyloxy)ethyl)-1,3,5-triazinane-2,4,6-trione. Examples of compounds having a carboxy group, a protected carboxy group, or an acid anhydride group include maleic acid, itaconic acid, trimellitic acid, tetracarboxylic acid, cis-1,2,3,4-tetrahydrophthalic acid, ethylene glycol bistrimate, propylene glycol bistrimate, 4,4'-oxydiphthalic acid, and trimellitic anhydride.

[0122] Compounds having a hydroxy group or a protected hydroxy group can preferably be compounds having a methylol group, a protected methylol group, a hydroxyalkylamide group, or a protected hydroxyalkylamide group. Specific examples of these include compounds represented by the following formulas (d2-1) to (d2-6) and (d3-1) to (d3-8).

[0123] Examples of compounds having an amino group or a protected amino group include compounds represented by the following formulae (d4-1) to (d4-5). Examples of compounds having a protected isocyanate group include compounds in which the isocyanate group in tolylene diisocyanate, xylylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, or diphenylmethane diisocyanate is protected with 3,6-dimethylpyrazole, methyl ethyl ketoxime, diethyl malonate, or ε-caprolactam, and compounds represented by the following formula (d5-1).

[0124] Examples of compounds having a group with a polymerizable carbon-carbon bond 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 (d6-1) to (d6-8).

[0125] [ka] [ka] (In formula (d2-5), Ac is an acetyl group.) [ka] [ka] [ka] [ka]

[0126] Among the above crosslinking agents, in terms of being able to achieve a well-balanced effect of improving liquid crystal alignment properties and low-voltage driving in liquid crystal elements, preferred are compounds having, in one molecule, two or more of at least one type of crosslinkable group selected from the group consisting of oxiranyl groups, protected oxiranyl groups, oxetanyl groups, hydroxyalkylamide groups, protected hydroxyalkylamide groups, amino groups, protected amino groups, methylol groups, and protected methylol groups, and more preferred are compounds having, in one molecule, two or more of at least one type of crosslinkable group selected from the group consisting of oxiranyl groups, protected oxiranyl groups, oxetanyl groups, hydroxyalkylamide groups, and protected hydroxyalkylamide groups.

[0127] As the crosslinking agent, a compound having no aromatic ring (hereinafter also referred to as "aliphatic crosslinking agent") can be preferably used, since it can provide a liquid crystal element having excellent liquid crystal alignment properties while sufficiently achieving low-voltage driving of the liquid crystal element. The aliphatic crosslinking agent may be a compound having a chain structure or may have a cyclic structure. Specific examples of the aliphatic crosslinking agent include compounds having no aromatic ring among the compounds exemplified above.

[0128] 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 alignment agent (i.e., the total amount of polymer (P) and other polymers) from the viewpoint of obtaining a liquid crystal alignment film that exhibits weak anchoring properties while improving the mechanical properties and adhesion of the liquid crystal alignment film. 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 viewpoint of obtaining a liquid crystal element that exhibits good liquid crystal alignment properties, the content of the crosslinking agent is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, relative to 100 parts by mass of the total amount of polymer components.

[0129] Adhesion aid The adhesion aid is a component that improves the adhesion between a liquid crystal alignment film formed using a liquid crystal alignment agent and a substrate or a sealant. A functional silane coupling agent having a reactive functional group can be preferably used as the adhesion aid. Examples of the reactive functional group possessed by the functional silane coupling agent include a carboxy group, a (meth)acryloyl group, an oxiranyl group, an oxetanyl group, a vinyl group, and an isocyanate group.

[0130] Specific examples of functional coupling agents include trimethoxysilylbenzoic acid, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, vinyltriacetoxysilane, vinyltrimethoxysilane, and 3-isocyanatopropyltriethoxysilane.

[0131] When the liquid crystal aligning agent of the present disclosure contains an adhesion aid, the content of the adhesion aid is preferably 0.1 to 20 parts by mass, more preferably 0.2 to 10 parts by mass, relative to 100 parts by mass of the polymer component contained in the liquid crystal aligning agent.

[0132] ·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.

[0133] The solvent is preferably an organic solvent, specific examples of which include amides such as N,N-dimethylformamide and N,N-dimethylacetamide, lactams such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone and γ-butyrolactam, ureas such as 1,2-dimethyl-2-imidazolidinone and 1,3-dimethyl-2-imidazolidinone, lactones such as γ-butyrolactone, carbonates such as ethylene carbonate and propylene carbonate, etc. (poly)alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-n-butyl ether (butyl cellosolve), diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-n-butyl ether, tripropylene glycol monomethyl ether, and tripropylene glycol monoethyl ether; Alkyl lactate esters such as methyl lactate, ethyl lactate, and butyl lactate; alkyl alcohols which may have a straight-chain, branched, or cyclic structure such as methanol, ethanol, propanol, butanol, isopropanol, isobutanol, t-butanol, octanol, 2-ethylhexanol, and cyclohexanol; alkoxy alcohols such as 3-methoxy-1-butanol; keto alcohols such as diacetone alcohol; ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, and diethylene glycol monoethyl ether acetate. (Poly)alkylene glycol monoalkyl ether acetates such as acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether acetate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, etc.; ethers such as diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, tetrahydrofuran, etc.; ketones such as methyl ethyl ketone, diisobutyl ketone, cyclohexanone, cyclopentanone, 2-heptanone, 3-heptanone, etc.; diacetates such as propylene glycol diacetate, 1,3-butylene glycol diacetate, and 1,6-hexanediol diacetate; alkoxycarboxylic acid esters such as methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, ethyl ethoxyacetate, and 3-methyl-3-methoxybutylpropionate; other esters such as ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, n-amyl formate, i-amyl acetate, n-butyl propionate, ethyl butyrate, n-propyl butyrate, i-propyl butyrate, n-butyl butyrate, methyl pyruvate, ethyl pyruvate, n-propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, and ethyl 2-oxobutanoate; aromatic hydrocarbons such as toluene and xylene; and phenols such as phenol and methylphenol.

[0134] In addition to the above, other components contained in the liquid crystal aligning agent include, for example, a surfactant, an antioxidant, a metal chelate compound, a curing accelerator, a filler, a dispersant, a photosensitizer, etc. The blending ratio of the other components can be appropriately selected depending on each compound within a range that does not impair the effects of the present disclosure.

[0135] The solid content concentration in the liquid crystal aligning agent (the proportion of the total mass of the components other than the solvent in the liquid crystal aligning agent to the total mass of the liquid crystal aligning agent) is appropriately selected taking into consideration viscosity, volatility, etc. The solid content concentration of the liquid crystal aligning agent is preferably in the range of 1 to 10 mass %. A solid content concentration of 1 mass % or more is preferable in that a sufficient thickness of the coating film can be ensured and a liquid crystal alignment film exhibiting better liquid crystal alignment properties can be obtained. Furthermore, a solid content concentration of 10 mass % or less can ensure an appropriate thickness of the coating film and makes it easier to obtain a liquid crystal alignment film exhibiting good liquid crystal alignment properties. Furthermore, the viscosity of the liquid crystal aligning agent becomes appropriate, ensuring good coatability.

[0136] <Weak anchoring liquid crystal alignment film and its manufacturing method> The liquid crystal alignment film of the present disclosure is a weak anchoring film produced by the liquid crystal alignment agent prepared as described above. The method for producing a weak anchoring liquid crystal alignment film using the liquid crystal alignment agent of the present disclosure is not particularly limited, and can be performed by the same method as when producing a liquid crystal alignment film using a conventionally known liquid crystal alignment agent. In terms of easy film formation, a method of forming the film by applying the liquid crystal alignment agent of the present disclosure to a substrate and heating the coated surface is preferred.

[0137] The substrate on which the liquid crystal alignment film is formed is not particularly limited. Examples of the substrate include transparent substrates made of glass such as float glass and soda glass, and plastics such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, and poly(alicyclic olefin).

[0138] The method for applying the liquid crystal aligning agent to the substrate is not particularly limited. The liquid crystal aligning agent can be applied by, for example, a spin coating method, a printing method (for example, an offset printing method, a flexographic printing method, etc.), an inkjet method, a slit coating method, a bar coater method, an extrusion die method, a direct gravure coater method, a chamber doctor coater method, an offset gravure coater method, an impregnation coater method, an MB coater method, etc.

[0139] After the liquid crystal alignment agent is applied, preheating (prebaking) is preferably carried out to prevent dripping of the liquid crystal alignment agent. The prebaking temperature is preferably 30 to 200°C, and the prebaking time is preferably 0.25 to 10 minutes. Thereafter, a baking (postbaking) step is carried out to further remove the solvent. The baking temperature (postbaking temperature) is preferably 80 to 280°C, more preferably 80 to 250°C. The postbaking time is preferably 5 to 200 minutes. The thickness of the formed film is preferably 0.001 to 2.5 μm. By the above-mentioned procedure, a weak anchoring liquid crystal alignment film can be easily produced. The coating film after postbaking may be subjected to an alignment treatment (for example, a rubbing alignment treatment or a photoalignment treatment) as necessary, thereby obtaining a weak anchoring liquid crystal alignment film. The weak anchoring liquid crystal alignment film of the present disclosure is preferably formed by a photo-alignment treatment using the liquid crystal aligning agent for forming a weak anchoring film of the present disclosure, which contains the polymer (P).

[0140] When a weak anchoring liquid crystal alignment film is formed by a photo-alignment treatment using the liquid crystal aligning agent for forming a weak anchoring film of the present disclosure, irradiation with radiation in the photo-alignment treatment can be carried out by a method of irradiating the coating film after the post-bake step, a method of irradiating the coating film after the pre-bake step but before the post-bake step, a method of irradiating the coating film while it is being heated in at least one of the pre-bake step and the post-bake step, etc. Among these, the method of irradiating the coating film after the post-bake step with radiation can be preferably used.

[0141] In the photo-alignment treatment, the radiation to be irradiated onto the coating film can be, for example, ultraviolet light containing light with a wavelength of 150 to 800 nm and visible light. 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. 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.

[0142] The light source used may be, for example, a low-pressure mercury lamp, a high-pressure mercury lamp, a deuterium lamp, or a metal lamp. Examples of the radiation that can be used include an alkyl halide lamp, an argon resonance lamp, a xenon lamp, and an excimer laser. The radiation dose is preferably 200 to 20,000 J / m 2 and more preferably 200 to 6,000 J / m 2 and more preferably 500 to 6,000 J / m 2 The coating film may be irradiated with light while being heated in order to enhance the reactivity.

[0143] In producing a weakly anchoring liquid crystal alignment film, the coating film that has been subjected to light irradiation treatment may be heated to further improve the liquid crystal alignment (thermal realignment). This heating is preferably a heat treatment performed after post-baking and separately from post-baking. When the coating film is heat-treated after radiation irradiation, the heating temperature is preferably 250°C or less, more preferably 200°C or less, and even more preferably 180°C or less, from the viewpoint of promoting the realignment of molecular chains by heating and obtaining a liquid crystal device with higher white luminance. Furthermore, the heating temperature is preferably 100°C or more, more preferably 120°C or more, from the viewpoint of promoting the realignment of molecular chains by heating and obtaining a liquid crystal device with better liquid crystal alignment. The heating time may be appropriately set depending on the heating temperature, but is preferably 5 to 200 minutes, more preferably 10 to 60 minutes.

[0144] From the viewpoint of obtaining a liquid crystal element having higher white brightness and a good contrast ratio, when obtaining a weak anchoring liquid crystal alignment film, it is preferable not to perform a heat treatment after exposure for the photo-alignment treatment, or to perform a heat treatment at a temperature of 200°C or less after exposure for the photo-alignment treatment.

[0145] 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. 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 heat-treated.

[0146] <Liquid crystal element and manufacturing method thereof> The liquid crystal element of the present disclosure comprises a pair of substrates consisting of a first substrate and a second substrate, a liquid crystal layer disposed between the pair of substrates, and further comprises a weak anchoring liquid crystal alignment film formed using the liquid crystal alignment agent for forming a weak anchoring film described above. The liquid crystal driving method in the liquid crystal element is not particularly limited, and various modes can be applied, such as TN type, STN type, VA type (including VA-MVA type, VA-PVA type, etc.), IPS type, FFS type, OCB (Optically Compensated Bend) type, PSA (Polymer Sustained Alignment) type, and ECB (Electrically Controlled Birefringence) type. Among these, the liquid crystal element is preferably applied to horizontal mode liquid crystal elements such as IPS type and FFS type.

[0147] The liquid crystal element of the present disclosure can be manufactured by a method including the following step A. In addition, a preferred embodiment of the method for manufacturing a liquid crystal element of the present disclosure is a method in which a weak anchoring liquid crystal alignment film is formed on one of a pair of substrates in step A, and further includes the following step B. By forming a liquid crystal alignment film on one of the pair of substrates using a liquid crystal aligning agent for forming a weak anchoring film containing a polymer (P) having a specific substructure, and forming a strong anchoring liquid crystal alignment film on the other, it is possible to achieve high brightness and low-voltage driving while ensuring good liquid crystal alignment properties and alignment uniformity. Step A: A step of forming a weak anchoring liquid crystal alignment film by applying the liquid crystal alignment agent for forming a weak anchoring film of the present disclosure to the surface of at least one of the pair of substrates and performing a photoalignment treatment. Step B: A step of forming a strong anchoring liquid crystal alignment film on the other substrate of the pair of substrates (i.e., the substrate on which the weak anchoring liquid crystal alignment film is not formed).

[0148] When a liquid crystal element is manufactured by a method including steps A and B, the order of steps A and B is not particularly limited. Specifically, step A may be performed followed by step B, or step B may be performed followed by step A. Alternatively, steps A and B may be performed simultaneously.

[0149] It is preferable that Step A and Step B include Step 1 and Step 2 shown below, respectively. Furthermore, a liquid crystal element can be obtained by constructing a liquid crystal cell in Step 3 using the substrates on which the liquid crystal alignment film obtained in Steps A and B is formed. Note that in Step 1, different substrates are used depending on the desired operation mode. Steps 2 and 3 are common to all operation modes.

[0150] <Step 1: Formation of coating film> In step 1, a liquid crystal alignment agent is applied to the surface of each substrate, and the coated surface is preferably heated to form a coating film on the substrate. When manufacturing a pair of substrates, for example, an IPS-type or FFS-type liquid crystal device, an electrode substrate with comb-shaped patterned electrodes is used as the first substrate, and an opposing substrate without electrodes is used as the second substrate. Examples of the electrode include a transparent conductive film. Examples of transparent conductive films that can be used include a NESA film (registered trademark of PPG, Inc., USA) made of tin oxide (SnO2) and an ITO film made of indium oxide-tin oxide (In2O3-SnO2). Examples of the formation of liquid crystal alignment films on the electrode substrate and opposing substrate include a first embodiment in which a strong anchoring liquid crystal alignment film is formed on the electrode substrate and a weak anchoring liquid crystal alignment film is formed on the opposing substrate; and a second embodiment in which a weak anchoring liquid crystal alignment film is formed on the electrode substrate and a strong anchoring liquid crystal alignment film is formed on the opposing substrate. Of these, the first embodiment is preferred because it can more fully achieve the effect of low-voltage operation of the liquid crystal device.

[0151] As a liquid crystal aligning agent for forming a strong anchoring liquid crystal alignment film (hereinafter also referred to as "liquid crystal aligning agent for forming a strong anchoring film"), a conventionally known liquid crystal aligning agent can be used as appropriate. As the polymer component of the liquid crystal aligning agent for forming a strong anchoring film, a polymer (hereinafter also referred to as "polymer (R)") containing a partial structure represented by the following formula (5) in its main chain can be preferably used. Note that by forming a liquid crystal alignment film using a liquid crystal aligning agent containing polymer (R), a strong anchoring liquid crystal alignment film containing polymer (R) can be obtained. [ka] (In formula (5), B 1 is a cyclic group. 2 and B 3 are each independently an aromatic ring group. "*" represents a bond to an atom contained in the polymer main chain.

[0152] In the above formula (5), B 1Examples of the cyclic group represented by the formula (I) include a tetravalent group obtained by removing four hydrogen atoms from the ring portion of a substituted or unsubstituted cycloalkane ring (for example, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, etc.); a tetravalent group obtained by removing four hydrogen atoms from the ring portion of a substituted or unsubstituted benzene ring, a naphthalene ring, or a biphenyl ring; etc. When the cyclic group has a substituent, examples of the substituent include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.), an alkyl group having 1 to 6 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, an acyl group, etc.

[0153] B 2 or B 3 Specific examples of the aromatic ring group represented by the formula (1) to the formula (3) include A 1 and A 2 Examples of the aromatic ring group include the same groups as those given as specific examples of the aromatic ring group B. 2 or B 3 Of these, the aromatic ring group represented by the formula (I) is preferably an aromatic hydrocarbon group, more preferably a phenylene group or a naphthalene group, and even more preferably a phenylene group.

[0154] Specific examples of the partial structure represented by the above formula (5) include partial structures represented by the following formulas (5-1) to (5-4). [ka] (In formulas (5-1) to (5-4), “* 2 " represents a bond to an atom contained in the polymer main chain.)

[0155] In terms of ease of introducing the partial structure represented by the above formula (5), the polymer (R) is preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide. The polyamic acid, polyamic acid ester, and polyimide having the partial structure represented by the above formula (5) can be obtained by using an alicyclic tetracarboxylic acid dianhydride or an aromatic tetracarboxylic acid dianhydride as the tetracarboxylic acid dianhydride and an aromatic diamine as the diamine compound.

[0156] The polymer component contained in the liquid crystal aligning agent for forming a strong anchoring film is not limited to the polymer (R), and may contain a polymer different from the polymer (R). Examples of such polymers include polymers having a partial structure represented by the following formula (6). [ka]

[0157] From the viewpoint of obtaining a liquid crystal element excellent in liquid crystal alignment properties (particularly AC afterimage characteristics), it is preferable that the liquid crystal aligning agent for forming a strong anchoring film substantially does not contain a polymer (P). Specifically, the content of the polymer (P) in the liquid crystal aligning agent for forming a strong anchoring film is preferably 0.5 mass % or less, more preferably 0.2 mass % or less, and even more preferably 0.05 mass % or less, based on the total amount of polymer components contained in the liquid crystal aligning agent for forming a strong anchoring film.

[0158] In addition, the liquid crystal aligning agent for forming a strong anchoring film preferably contains a crosslinking agent together with the polymer component, in order to improve the mechanical strength of the liquid crystal alignment film and adhesion to the substrate. Examples of the crosslinking agent include the same compounds as those exemplified as the crosslinking agents that may be contained in the liquid crystal aligning agent for forming a weak anchoring film.

[0159] <Step 2: Alignment Treatment> When manufacturing an IPS or FFS liquid crystal element, it is preferable to subject the coating film formed on the substrate in step 1 to a treatment (alignment treatment) to impart liquid crystal alignment ability. As the alignment treatment, a rubbing treatment in which the surface of the coating film formed on the substrate is rubbed with cotton, nylon, or the like, or a photo-alignment treatment in which the coating film is irradiated with light to impart liquid crystal alignment ability is preferably used. Of these, a weak anchoring liquid crystal alignment film is preferably obtained by a photo-alignment treatment. Furthermore, a strong anchoring liquid crystal alignment film is preferably obtained by a rubbing treatment or a photo-alignment treatment. When a strong anchoring liquid crystal alignment film is obtained by a photo-alignment treatment, the exposure conditions are the same as those when a weak anchoring liquid crystal alignment film is obtained.

[0160] Specifically, it is preferable to obtain a liquid crystal element by the following methods 1 and 2. (Method 1) A method in which the strong anchoring alignment film is a rubbed alignment film, and in the process of forming a weak anchoring liquid crystal alignment film, no heat treatment is performed after exposure for photo-alignment treatment, or the heat treatment is performed at a temperature of 200°C or less. (Method 2) The strong anchoring alignment film is a photo-alignment film, and in the step (step B) of forming the strong anchoring alignment film, a heat treatment is carried out at a first temperature after exposure for the photo-alignment treatment, and in the step (step A) of forming the weak anchoring liquid crystal alignment film, either no heat treatment is carried out after exposure for the photo-alignment treatment or the heat treatment is carried out at a second temperature lower than the first temperature.

[0161] In Method 2, the first temperature may be higher than the second temperature. Specifically, the first temperature is preferably 180 to 300° C., and more preferably more than 200° C. but not more than 300° C. The preferred range of the second temperature is as described above.

[0162] <Step 3: Construction of liquid crystal cell> Next, a liquid crystal cell is produced using two substrates arranged opposite each other, one with a strong anchoring liquid crystal alignment film and the other with a weak anchoring liquid crystal alignment film, with a liquid crystal layer disposed between them. Examples of methods for producing a liquid crystal cell include: arranging two substrates opposite 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 the like. Examples of sealants that can be used include epoxy resins containing a curing agent and aluminum oxide spheres as spacers. Either positive or negative liquid crystals can be used as the liquid crystal constituting the liquid crystal layer. Examples of liquid crystals that can be used for the liquid crystal layer include nematic liquid crystals and smectic liquid crystals, with nematic liquid crystals being preferred.

[0163] When manufacturing a liquid crystal display element, a polarizing plate is subsequently attached to the outer surface of the liquid crystal cell. 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.

[0164] The liquid crystal element of the present disclosure can be effectively applied to various applications, specifically, for example, various display devices such as clocks, 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 devices, retardation films, and the like.

[0165] Another embodiment of the method for manufacturing a liquid crystal element according to the present disclosure includes the steps of: forming a first liquid crystal alignment film by applying the liquid crystal alignment agent for forming a weak anchoring film according to the present disclosure to the surface of at least one of the first and second substrates and performing a photo-alignment treatment; and forming a second liquid crystal alignment film on the surface of one of the first and second substrates, which is different from the substrate on which the first liquid crystal alignment film is formed, wherein the second liquid crystal alignment film contains a polymer (R). The second liquid crystal alignment film is preferably manufactured by performing a rubbing treatment or a photo-alignment treatment using a liquid crystal alignment agent containing a polymer (R). The details of the polymer (R), the rubbing treatment, and the photo-alignment treatment are as described above.

[0166] Another aspect of the method for manufacturing a liquid crystal element of the present disclosure includes a step of forming a first liquid crystal alignment film on the surface of one of the first and second substrates by a photo-alignment method, and a step of forming a second liquid crystal alignment film on the surface of one of the first and second substrates, which is different from the substrate on which the first liquid crystal alignment film is formed, by a rubbing method, and in the step of forming the first liquid crystal alignment film, either no heat treatment is performed after exposure for the photo-alignment treatment, or the heat treatment is performed at a temperature of 200°C or less.

[0167] Furthermore, another aspect of the method for manufacturing a liquid crystal element according to the present disclosure includes the steps of forming a first liquid crystal alignment film on the surface of a first substrate by a photo-alignment method, and forming a second liquid crystal alignment film on the surface of a second substrate by a photo-alignment method, wherein in the step of forming one of the first and second liquid crystal alignment films, a heat treatment is carried out at a first temperature after exposure for the photo-alignment treatment, and in the step of forming the other liquid crystal alignment film, either no heat treatment is carried out after exposure for the photo-alignment treatment or a heat treatment is carried out at a second temperature lower than the first temperature. Details of the formation of the liquid crystal alignment film and the heat treatment in these other aspects are as described above.

[0168] The present disclosure described above in detail includes the following aspects [1] to

[18] . [1] A liquid crystal aligning agent for forming a weak anchoring film, which is used to form a weak anchoring liquid crystal alignment film, and which contains a polymer (P) having at least one structure selected from the group consisting of a partial structure represented by the above formula (1), a partial structure represented by the above formula (2), a partial structure represented by the above formula (3), a partial structure represented by the above formula (4), an azobenzene structure, a chalcone structure, a coumarin structure, and a chromanone structure. [2] The liquid crystal aligning agent for forming a weak anchoring film according to [1], wherein the polymer (P) is at least one selected from the group consisting of addition polymers, polyamic acids, polyamic acid esters, polyimides, and polyorganosiloxanes. [3] The liquid crystal aligning agent for forming a weak anchoring film according to [1] or [2], further comprising a polymer (Q) different from the polymer (P). [4] The liquid crystal aligning agent for forming a weak anchoring film according to [3], wherein the polymer (Q) is at least one selected from the group consisting of addition polymers, polyamic acids, polyamic acid esters, polyimides, and polyorganosiloxanes. [5] The liquid crystal aligning agent for forming a weak anchoring film according to [3] or [4], wherein the polymer (Q) comprises a polymer (Q1) having at least one of an alkyl group having 5 or more carbon atoms and a cycloalkyl group having 7 or more carbon atoms in a side chain. [6] The liquid crystal aligning agent for forming a weak anchoring film according to [5], wherein the polymer (Q) further contains a polymer different from the polymer (Q1). [7] The liquid crystal aligning agent for forming a weak anchoring film according to any one of [1] to [6], further comprising a crosslinking agent. [8] The liquid crystal aligning agent for forming a weak anchoring film according to [7], wherein the crosslinking agent does not have an aromatic ring. [9] A method for producing a liquid crystal alignment film, comprising forming a weak anchoring liquid crystal alignment film using the liquid crystal aligning agent for forming a weak anchoring film according to any one of [1] to [8].

[10] A method for manufacturing a liquid crystal element comprising a pair of substrates consisting of a first substrate and a second substrate, and a liquid crystal layer disposed between the pair of substrates, the method comprising the steps of applying a liquid crystal alignment agent for forming a weak anchoring film described in any one of [1] to [8] to the surface of at least one of the first substrate and the second substrate, and performing a photoalignment treatment to form a weak anchoring liquid crystal alignment film.

[11] A method for manufacturing a liquid crystal element described in

[10] , further comprising the steps of forming the weak anchoring liquid crystal alignment film on the surface of one of the first substrate and the second substrate, and forming a strong anchoring liquid crystal alignment film having stronger anchoring energy than the weak anchoring liquid crystal alignment film on the surface of one of the first substrate and the second substrate other than the substrate on which the weak anchoring liquid crystal alignment film is formed.

[12] The method for manufacturing a liquid crystal element described in

[11] , wherein the strong anchoring alignment film is a rubbed alignment film, and in the process of forming the weak anchoring liquid crystal alignment film, a heat treatment is not performed after exposure for photo-alignment treatment, or a heat treatment is performed at a temperature of 200°C or less.

[13] A method for manufacturing a liquid crystal element described in

[11] , wherein the strong anchoring alignment film is a photo-alignment film, and in the process of forming the strong anchoring alignment film, a heat treatment is performed at a first temperature after exposure for the photo-alignment treatment, and in the process of forming the weak anchoring liquid crystal alignment film, either no heat treatment is performed after exposure for the photo-alignment treatment or a heat treatment is performed at a second temperature lower than the first temperature.

[14] A method for manufacturing a liquid crystal element described in

[11] , wherein the first substrate has a pair of electrodes and the second substrate has no electrodes, the strong anchoring liquid crystal alignment film is formed on the surface of the first substrate, and the weak anchoring liquid crystal alignment film is formed on the surface of the second substrate.

[15] The method for producing a liquid crystal device according to any one of

[11] to

[14] , wherein the strong anchoring liquid crystal alignment film contains a polymer having a partial structure represented by the above formula (5) in its main chain.

[16] A method for manufacturing a liquid crystal device comprising a pair of substrates consisting of a first substrate and a second substrate, and a liquid crystal layer disposed between the pair of substrates, the method comprising the steps of: forming a first liquid crystal alignment film by applying a liquid crystal alignment agent for forming a weak anchoring film according to any one of [1] to [8] to a surface of at least one of the first substrate and the second substrate and performing a photo-alignment treatment; and forming a second liquid crystal alignment film on a surface of one of the first substrate and the second substrate that is different from the substrate on which the first liquid crystal alignment film is formed, wherein the second liquid crystal alignment film contains a polymer having a partial structure represented by the above formula (5) in its main chain.

[17] A method for manufacturing a liquid crystal element comprising a pair of substrates consisting of a first substrate and a second substrate, and a liquid crystal layer disposed between the pair of substrates, the method comprising: forming a first liquid crystal alignment film on a surface of one of the first and second substrates by a photo-alignment method; and forming a second liquid crystal alignment film on a surface of one of the first and second substrates, which is different from the substrate on which the first liquid crystal alignment film is formed, by a rubbing method, wherein in the step of forming the first liquid crystal alignment film, a heat treatment is not performed after exposure for the photo-alignment treatment, or a heat treatment is performed at a temperature of 200°C or less.

[18] A method for manufacturing a liquid crystal element comprising a pair of substrates consisting of a first substrate and a second substrate, and a liquid crystal layer disposed between the pair of substrates, the method comprising: forming a first liquid crystal alignment film on a surface of the first substrate by a photo-alignment method; and forming a second liquid crystal alignment film on a surface of the second substrate by a photo-alignment method, wherein in the step of forming one of the first and second liquid crystal alignment films, a heat treatment is performed at a first temperature after exposure for the photo-alignment treatment, and in the step of forming the other liquid crystal alignment film, either no heat treatment is performed after exposure for the photo-alignment treatment, or a heat treatment is performed at a second temperature lower than the first temperature. [Example]

[0169] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0170] In the following examples, the imidization rate of polyimide and the molecular weight (Mw, Mn) of the polymer were measured by the following methods. <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-(β 1 / (β 2 ×α)))×100 …(1) (In formula (1), β 1 is the peak area due to the proton of the NH group that appears at a chemical shift of around 10 ppm, and β 2 is the peak area due to other protons, and α is the ratio of the number of other protons to one proton of the NH group in the polymer precursor (polyamic acid). <Polymer molecular weight (Mw, Mn)> The weight average molecular weight (Mw) and number average molecular weight (Mn) were measured by gel permeation chromatography (GPC) under the following conditions. Equipment: Showa Denko "GPC-101" GPC column: Shimadzu GLC's "GPC-KF-801", "GPC-KF-802", "GPC-KF-803" and "GPC-KF-804" Mobile phase: tetrahydrofuran (THF) Column temperature: 40℃ Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Detector: differential refractometer Standard material: monodisperse polystyrene

[0171] The abbreviations of the compounds used in the following examples are shown below. For convenience, hereinafter, "a compound represented by formula (X)" may be simply referred to as "compound (X)." In the examples and comparative examples, "parts" and "%" are by mass unless otherwise specified.

[0172] (Tetracarboxylic dianhydrides) T-1 to T-8 [ka]

[0173] (Diamine) DA-1 to DA-7, DB-1 to DB-14 [ka] [ka]

[0174] (Monomers having unsaturated bonds) MA-1 to MA-10, MB-1 to MB-10 [ka] [ka]

[0175] (Siloxane monomer, epoxy group-containing polyorganosiloxane, side chain carboxylic acid) S-1, CA-1 to CA-3, CB-1 to CB-4 [ka]

[0176] (Additives) AD-1 to AD-8 [ka]

[0177] <Polymer synthesis>

[0178] 1. Synthesis of polyamic acid [Synthesis Example 1] 100 parts by mole of compound (T-4) as a tetracarboxylic dianhydride, and 50 parts by mole of compound (DA-1) and 50 parts by mole of compound (DB-11) as diamine compounds were dissolved in N-methyl-2-pyrrolidone (NMP), and the reaction was carried out at 60°C for 6 hours to obtain a solution containing 20% ​​by mass of polyamic acid (referred to as polymer (PAA-1)).

[0179] [Synthesis Examples 3, 5-7, 9-15] Polyamic acids (referred to as polymers (PAA-3), (PAA-5) to (PAA-7), and (PAA-9) to (PAA-15) respectively) were obtained by the same procedure as in Synthesis Example 1, except that the types and amounts of the tetracarboxylic dianhydrides and diamine compounds used were changed as shown in Table 1. In Table 1, the numerical values ​​for the tetracarboxylic dianhydrides (acid dianhydrides 1 to 3) represent the ratio (molar ratio) of each compound relative to 100 parts by mole of the total amount of tetracarboxylic dianhydrides used in the synthesis of the polymer. The numerical values ​​for the diamine compounds (diamines 1 to 4) represent the ratio (molar ratio) of each compound relative to 100 parts by mole of the total amount of diamine compounds used in the synthesis of the polymer.

[0180] 2. Polyimide Synthesis [Synthesis Example 2] 100 moles of compound (T-4) as a tetracarboxylic dianhydride, and 30 moles of compound (DA-1), 30 moles of compound (DB-10), 30 moles of compound (DB-11), and 10 moles of compound (DB-13) as diamine compounds were dissolved in NMP and reacted at 60 ° C for 6 hours to obtain a solution containing 20 mass% polyamic acid. Next, NMP was added to the obtained polyamic acid solution to obtain a solution with a polyamic acid concentration of 10 mass%, and pyridine and acetic anhydride were added, followed by a dehydration ring-closing reaction at 80 ° C for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with fresh NMP to obtain a solution containing 15 mass% polyimide (referred to as polymer (PAA-2)) with an imidization rate of approximately 30%.

[0181] [Synthesis Examples 4 and 8] Polyimides (referred to as polymers (PAA-4) and (PAA-8), respectively) were obtained by the same procedure as in Synthesis Example 2, except that the types and amounts of the tetracarboxylic dianhydrides and diamine compounds used were changed as shown in Table 1.

[0182] [Table 1]

[0183] 3. Synthesis of addition polymers [Synthesis Example 16] Under nitrogen, a 100 mL two-neck flask was charged with 10 mol parts of compound (MB-1), 45 mol parts of compound (MB-3), and 45 mol parts of compound (MB-5), 0.3922 g of 2,2'-azobis(2,4-dimethylvaleronitrile) as a radical polymerization initiator (10 parts by mass relative to 100 parts by mass of the total amount of polymerization monomers), and 15.68 g of N-methyl-2-pyrrolidone (NMP) as a solvent (400 parts by mass relative to 100 parts by mass of the total amount of polymerization monomers) under a nitrogen atmosphere. Polymerization was carried out for 6 hours at 70 °C. After reprecipitation in methanol, the precipitate was filtered and dried under vacuum at room temperature for 8 hours to obtain the desired addition polymer (referred to as polymer (PM-1)).

[0184] [Synthesis Examples 17 to 31] The same procedure as in Synthesis Example 16 was carried out except that the types and amounts of the polymerizable monomers used were changed as shown in Table 2, to obtain addition polymers (referred to as polymers (PM-2) to (PM-16) respectively).

[0185] [Table 2]

[0186] 4. Synthesis of polyorganosiloxane [Synthesis Example 32] A 1000 mL three-neck flask was charged with 100.0 g of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (compound (S-1)), 500 g of methyl isobutyl ketone, and 10.0 g of triethylamine, and mixed at room temperature. Next, 100 g of deionized water was added dropwise from the dropping funnel over 30 minutes, and the mixture was stirred under reflux while reacting at 80°C for 6 hours. After the reaction was completed, the organic layer was removed and washed with a 0.2% by weight aqueous solution of ammonium nitrate until the water after washing was neutral, after which the solvent and water were distilled off under reduced pressure. An appropriate amount of methyl isobutyl ketone was added to obtain a 50% by weight solution of a polyorganosiloxane having epoxy groups (referred to as "polymer (ESQ-1)"). A 500 mL three-neck flask was charged with 10 mol% of compound (CB-1) and 15 mol% of compound (CB-3) relative to the amount of epoxy groups in polymer (ESQ-1). 1.00 g of tetrabutylammonium bromide, 20.0 g of a solution containing polymer (ESQ-1), and 290.0 g of methyl isobutyl ketone were then added and stirred at 90 ° C for 18 hours. After cooling to room temperature, the separation and washing operation with distilled water was repeated 10 times. The organic layer was then recovered, concentrated using a rotary evaporator, and diluted with NMP twice. The solids concentration was then adjusted to 10% by mass using NMP to obtain an NMP solution of polyorganosiloxane (referred to as polymer (PS-1)).

[0187] [Synthesis Examples 33 to 39] Polyorganosiloxanes (referred to as polymers (PS-2) to (PS-8) respectively) were obtained in the same manner as in Synthesis Example 32, except that the type and amount of side-chain carboxylic acid used were changed as shown in Table 3. In Table 3, the amount of side-chain carboxylic acid is the ratio (mol %) to the amount of epoxy groups in the precursor polymer (ESQ-1).

[0188] [Table 3]

[0189] <Preparation of Liquid Crystal Alignment Agent> [Preparation Example 1] A solution containing 30 parts by mass of the polymer (PAA-1) obtained in Synthesis Example 1 and a solution containing 70 parts by mass of the polymer (PAA-14) obtained in Synthesis Example 14 were mixed, 5 parts by mass of compound (AD-2) were added, and the mixture was further diluted with N-methyl-2-pyrrolidone (NMP), gamma butyrolactone (GBL), butyl cellosolve (BC), diacetone alcohol (DAA), and diethylene glycol diethyl ether (DEDG) to obtain a solution with a solvent composition of NMP:GBL:BC:DAA:DEDG = 30:30:15:15:10 (mass ratio) and a solids concentration of 3.5 mass%. The solution was filtered through a filter with a pore size of 0.2 μm to prepare a liquid crystal alignment agent (AL-1).

[0190] [Preparation Examples 2-35] A liquid crystal alignment agent was prepared in the same manner as in Preparation Example 1, except that the polymer and additives contained in the liquid crystal alignment agent were changed as shown in the following Table 4. In Table 4, the numerical values ​​in the polymer column and additive column represent the blending ratio (parts by mass) of the solid content of each compound relative to 100 parts by mass of the total amount of the polymer components used in the preparation of the liquid crystal alignment agent.

[0191] [Table 4]

[0192] <Production and evaluation of liquid crystal display elements> [Example 1: Manufacture of FFS-type liquid crystal display element by rubbing alignment method / photoalignment method] An FFS-type liquid crystal display element 10 shown in Fig. 1 was manufactured, and various characteristics were evaluated. In manufacturing the FFS-type liquid crystal display element 10, first, a substrate (referred to as a first substrate) having an electrode pair formed in this order on one surface of a glass substrate 11a, a bottom electrode 15 having no pattern, an insulating layer 14 made of a silicon nitride film, and a top electrode 13 patterned in a comb-like shape, and an opposing glass substrate 11b (referred to as a second substrate) having no electrode were prepared. A schematic plan view of the top electrode 13 used is shown in Figure 2. Note that Figure 2(a) is a top view of the top electrode 13, and Figure 2(b) is an enlarged view of the area C1 enclosed by the dashed line in Figure 2(a). In this example, the electrode line width d1 was 3 μm, and the distance between the electrodes d2 was 3 μm. Four systems of drive electrodes, electrodes A, B, C, and D, were used as the top electrode 13 (Figure 3). Note that the bottom electrode 15 acts as a common electrode that affects all four systems of drive electrodes, and each of the areas of the four systems of drive electrodes becomes a pixel area. Note that in Figure 1, reference numeral 12 denotes a liquid crystal alignment film, and reference numeral 16 denotes a liquid crystal layer.

[0193] (i) Formation of weakly anchoring liquid crystal alignment film by photoalignment method A liquid crystal alignment agent (AL-1) was applied to one side of the second substrate using a spin coater. The substrate was then heated on a hot plate at 80°C for 1 minute, and then heated in a nitrogen-purged oven at 230°C for 30 minutes to form a coating film with an average thickness of 100 nm. A Hg-Xe lamp was used to irradiate the surface of the coating film with 200 mJ / cm of linearly polarized ultraviolet light containing a 254 nm emission line. 2 The photo-alignment treatment was performed by irradiating the polarized UV light from the normal direction of the substrate. The direction of the polarization plane was set so that the direction of the line segment projected onto the substrate was perpendicular to the direction of the double-headed arrow in Figure 2(b). The photo-alignment treatment was not performed on the coating film. This resulted in the formation of a weakly anchored liquid crystal alignment film.

[0194] (ii) Formation of a strong anchoring liquid crystal alignment film by rubbing alignment method A liquid crystal alignment agent (AL-19) was applied to the electrode-forming surface of the first substrate using a spin coater. The coating was then heated on a hot plate at 80°C for 1 minute, followed by heating in a nitrogen-purged oven at 230°C for 30 minutes to form a coating with an average thickness of 100 nm. The coating surface was then rubbed twice using a rubbing machine equipped with a roll wrapped in rayon cloth at a roll rotation speed of 1,000 rpm, a stage movement speed of 30 mm / s, and a pile depth of 0.3 mm. The rubbing direction was set parallel to the direction of the double-headed arrow in Figure 2(b). The rubbed coating was then ultrasonically cleaned in ultrapure water for 1 minute and then dried in an oven at 100°C for 10 minutes to form a strong-anchoring liquid crystal alignment film.

[0195] (iii) Manufacture of FFS type liquid crystal display elements An epoxy resin adhesive containing 3.5 μm diameter aluminum oxide spheres was dispensed onto the outer periphery of the surface bearing the liquid crystal alignment film of one of the substrates prepared in steps (i) and (ii), leaving a liquid crystal injection port. The surfaces bearing the liquid crystal alignment films of the pair of substrates were then pressed together, facing each other, and the adhesive was thermally cured at 150°C for 1 hour. Next, a positive liquid crystal (MLC-7028-100, manufactured by Merck) was filled into the gap between the 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.

[0196] (iv) Evaluation of liquid crystal alignment (AC image retention characteristics) The liquid crystal display element manufactured in (iii) above was subjected to application of an AC voltage that resulted in maximum brightness, and the change in liquid crystal azimuth angle was measured before and after driving for two days using a birefringence meter (AXOMETRICS, AXOSTEP high-precision Mueller matrix imaging polarimeter). A change in liquid crystal azimuth angle of less than 0.5 degrees was evaluated as "good (◎)," a change of 0.5 degrees to less than 1 degree was evaluated as "fair (○)," and a change of 1 degree or more was evaluated as "poor (×)." The smaller the change in liquid crystal azimuth angle, the less likely AC afterimages are to occur even when the liquid crystal display element is driven for a long period of time, and the better the liquid crystal alignment. As a result, this example was evaluated as "good (◎)."

[0197] (v) Evaluation of low-voltage operation The liquid crystal display element fabricated in (iii) above was sandwiched between two polarizing plates to minimize brightness, and the liquid crystal display element was placed between a backlight and a luminance meter, with the optical axes aligned. Voltages up to 10 V were then applied to the liquid crystal display element in 0.1 V increments. The VT curve was obtained by measuring the brightness versus applied voltage, and the voltage at which brightness reached maximum was estimated. A reference cell was also prepared by forming a liquid crystal alignment film on the second substrate using the same liquid crystal alignment agent (AL-19) as the first substrate using the rubbing alignment method. The evaluation was based on the degree to which the maximum brightness voltage of the liquid crystal display element was reduced relative to the maximum brightness voltage of the reference cell. A liquid crystal display element fabricated in (iii) above with a maximum brightness voltage greater than 0.8 V lower than the maximum brightness voltage of the reference cell was evaluated as "good (◎)," a liquid crystal display element fabricated in (iii) above with a maximum brightness voltage greater than 0 V but not greater than 0.8 V lower than the maximum brightness voltage of the reference cell was evaluated as "fair (○)," and a reference cell with a maximum brightness voltage lower than 0 V was evaluated as "poor (×)." As a result, the present example was evaluated as "Fair (◯)".

[0198] (vi) Evaluation of orientation uniformity For the liquid crystal cell manufactured in (iii) above, the retardation was measured at 20 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 0.075 or less, it was "good (◎)", if it was greater than 0.075 and less than 0.085, it was "passable (○)", and if it was greater than 0.085, it was "poor (×)". As a result, the alignment uniformity of this example was evaluated as "good (◎)".

[0199] (vii) Evaluation of white luminance The liquid crystal display element manufactured in (iii) above was sandwiched between a polarizer and an analyzer under crossed Nicols, and a square-wave AC voltage was swept from 0 V to 8 V in 0.5 V intervals to measure the transmission luminance of the liquid crystal display element. The transmission luminance when no voltage was applied under parallel Nicols was defined as 100%, and the maximum transmittance was calculated from the maximum transmission luminance during the voltage sweep. A maximum transmittance of 75% or more was evaluated as "good (◎)," a maximum transmittance of 70% or more but less than 75% was evaluated as "fair (○)," and a maximum transmittance of less than 70% was evaluated as "poor (×)." As a result, this example was evaluated as "good (◎)."

[0200] (viii) Evaluation of response speed The liquid crystal cell prepared in (iii) above was sandwiched between two polarizing plates arranged in a crossed Nicol configuration and then connected to a function generator. The liquid crystal cell connected to the function generator was placed on a backlight. First, the luminance of light transmitted through the liquid crystal cell without applying voltage was measured using a photomultimeter. This value was designated as 0% relative transmittance. Next, a square wave with a positive and negative amplitude corresponding to the maximum luminance voltage obtained in "(v) Evaluation of Low-Voltage Driving" above was applied between the electrodes of the liquid crystal cell using the function generator for 1 second. The transmittance was measured in the same manner as above, and this value was designated as 100% relative transmittance. Furthermore, a square wave with a positive and negative amplitude corresponding to the maximum luminance voltage obtained in "(v) Evaluation of Low-Voltage Driving" above was applied to each liquid crystal cell using the function generator. The time required for the relative transmittance to change from 10% to 90% was measured, and this time was defined as the response speed of the liquid crystal in the ON state (when voltage was applied). In addition, when the application of the square wave was stopped and switched to a 0V state, the time until the relative transmittance changed from 90% to 10% was measured, and this time was defined as the response speed in the OFF state (when the voltage application was removed). The response speed of the liquid crystal cell was evaluated by the sum of the response speed in the ON state and the response speed in the OFF state. If the sum of the response speed in the ON state and the response speed in the OFF state was less than 90 ms, it was rated as "good (◎)", if it was 90 ms or more but less than 150 ms, it was rated as "passable (○)", and if it was 150 ms or more, it was rated as "poor (×)". As a result, in this example, the response speed was judged to be "good (◎)".

[0201] [Examples 2, 7, 8, 10, 12, 15, 17 to 20, 22 to 26, 28, 29, and Comparative Example 5: Production of FFS-Type Liquid Crystal Display Devices by Rubbing Alignment Method / Photo-Alignment Method] FFS-type liquid crystal display elements were manufactured by the rubbing alignment method / photoalignment method in the same manner as in Example 1, except that the liquid crystal alignment agent used was changed as shown in Table 5, and various evaluations were performed. In the photoalignment treatment of an example using a polymer having a cinnamate structure as the photoalignment structure, linearly polarized ultraviolet light containing a 313 nm emission line was used, and in the photoalignment treatment of an example using a polymer having an azobenzene structure, linearly polarized ultraviolet light containing a 365 nm emission line was used (the same applies to the following examples). The evaluation results are shown in Table 5.

[0202] [Examples 4, 5, 6, 11, 14, and 16, and Comparative Example 1: Production of FFS-type liquid crystal display elements by rubbing alignment method / photoalignment method (with post-exposure baking)] FFS-type liquid crystal display elements were manufactured by the rubbing alignment method / photo-alignment method in the same manner as in Example 1, except that the liquid crystal alignment agent used was changed as shown in Table 5, and when forming the liquid crystal alignment film (weak anchoring liquid crystal alignment film for Examples 4, 5, 6, 11, 14, and 16) on the second substrate, the photo-aligned coating film was heat-treated by heating it for 30 minutes in an oven with the inside of the oven replaced with nitrogen at the temperature shown in Table 5. The evaluation results are shown in Table 5.

[0203] [Example 3: Photo-alignment method / Fabrication of FFS-type liquid crystal display element by photo-alignment method] An FFS-type liquid crystal display element 10 shown in FIG. 1 was manufactured and various characteristics were evaluated. (i) Formation of weakly anchoring liquid crystal alignment film by photoalignment method A liquid crystal alignment agent (AL-3) was applied to one side of the second substrate using a spin coater. The substrate was then heated on a hot plate at 80°C for 1 minute, and then heated in a nitrogen-purged oven at 230°C for 30 minutes to form a coating film with an average thickness of 100 nm. A Hg-Xe lamp was used to irradiate the surface of the coating film with 200 mJ / cm of linearly polarized ultraviolet light containing a 254 nm emission line. 2The photo-alignment treatment was performed by irradiating the polarized UV light from the normal direction of the substrate. The direction of the polarization plane was set so that the direction of the line segment projected onto the substrate was perpendicular to the direction of the double-headed arrow in Figure 2(b). The photo-alignment treatment was not performed on the coating film. This resulted in the formation of a weakly anchored liquid crystal alignment film.

[0204] (ii) Formation of a strong anchoring liquid crystal alignment film by photoalignment method A liquid crystal alignment agent (AL-17) was applied to the electrode-formed surface of the first substrate using a spin coater. The substrate was then heated on a hot plate at 80°C for 1 minute, and then heated in a nitrogen-purged oven at 230°C for 30 minutes to form a coating film with an average thickness of 100 nm. A Hg-Xe lamp was used to irradiate the surface of the coating film with 200 mJ / cm of linearly polarized ultraviolet light containing a 254 nm emission line. 2 The photo-alignment treatment was performed by irradiating the polarized UV light from the normal direction of the substrate. The direction of the polarization plane was set so that the direction of the line segment projected onto the substrate was perpendicular to the direction of the double-headed arrow in Figure 2(b). The photo-alignment-treated coating film was then heat-treated in a nitrogen-purged oven at 230°C for 30 minutes to form a strong anchoring liquid crystal alignment film.

[0205] (iii) Manufacture of FFS type liquid crystal display elements Using the pair of substrates prepared in (i) and (ii) above, the same operation as in Example 1 was carried out to produce a photo-aligned FFS-mode liquid crystal display element.

[0206] (iv) Evaluation of liquid crystal alignment (AC image retention characteristics) The liquid crystal display element manufactured in (iii) above was evaluated for liquid crystal alignment properties (AC afterimage characteristics) in the same manner as in Example 1. As a result, this example was evaluated as "fair (◯)." (v) Evaluation of low-voltage operation The liquid crystal display element produced in (iii) above was evaluated for low-voltage driving in the same manner as in Example 1. As a result, this example was evaluated as "Fair (◯)". (vi) Evaluation of orientation uniformity The liquid crystal display element manufactured in (iii) above was evaluated for alignment uniformity in the same manner as in Example 1. As a result, this example was evaluated as "good (A)". (vii) Evaluation of white luminance The white luminance of the liquid crystal display element produced in (iii) above was evaluated in the same manner as in Example 1. As a result, the liquid crystal display element in this example was evaluated as "good (A)". (viii) Evaluation of response speed The response speed of the liquid crystal display element manufactured in (iii) above was evaluated in the same manner as in Example 1. As a result, the response speed of this example was evaluated as "good (A)".

[0207] [Examples 21 and 27: Photo-alignment method / Fabrication of FFS-type liquid crystal display element by photo-alignment method] FFS-mode liquid crystal display elements were produced by the photoalignment method in the same manner as in Example 3, except that the liquid crystal alignment agent used was changed as shown in Table 5, and various evaluations were carried out. The evaluation results are shown in Table 5.

[0208] [Examples 9 and 13, Comparative Example 2: Production of FFS-type liquid crystal display element by photoalignment method / photoalignment method (with post-exposure baking)] FFS-type liquid crystal display elements were manufactured by the photo-alignment method in the same manner as in Example 3, except that the liquid crystal alignment agent used was changed as shown in Table 5, and when forming the liquid crystal alignment film (weak anchoring liquid crystal alignment film in Examples 9 and 13) on the second substrate, the coating film that had been subjected to the photo-alignment treatment was heat-treated by heating it for 30 minutes at the temperature shown in Table 5 in an oven whose interior was replaced with nitrogen, and various evaluations were performed. The evaluation results are shown in Table 5.

[0209] Comparative Example 3: Manufacture of FFS-type liquid crystal display element by rubbing alignment method / rubbing alignment method A liquid crystal alignment film was formed in the same manner as in Example 1, except that the liquid crystal alignment agent used was changed as shown in Table 5 and that the coating film formed on the second substrate was also subjected to a rubbing alignment treatment, and an FFS-type liquid crystal display element was manufactured and subjected to various evaluations. The conditions for the rubbing alignment treatment on the coating film formed on the second substrate were the same as those for the liquid crystal alignment film formed using a strong anchoring liquid crystal alignment agent. The evaluation results are shown in Table 5.

[0210] Comparative Example 4: Production of FFS-Type Liquid Crystal Display Element by Photo-Alignment Method / Rubbing Alignment Method A liquid crystal alignment film was formed in the same manner as in Example 3, except that the liquid crystal alignment agent used was changed as shown in Table 5 and that the coating film formed on the second substrate was subjected to a rubbing alignment treatment, and an FFS-type liquid crystal display element was manufactured and subjected to various evaluations. The conditions for the rubbing alignment treatment on the coating film formed on the second substrate were the same as those for the liquid crystal alignment film formed using the strong anchoring liquid crystal alignment agent in Example 1. The evaluation results are shown in Table 5.

[0211] Comparative Example 6: Manufacture of FFS-type liquid crystal display element by rubbing alignment method / without alignment treatment A liquid crystal alignment film was formed in the same manner as in Example 1, except that the liquid crystal alignment agent used was changed as shown in Table 5 and no alignment treatment was performed on the coating film formed on the second substrate, and an FFS-type liquid crystal display element was manufactured and various evaluations were performed. The evaluation results are shown in Table 5.

[0212] [Table 5]

[0213] As shown in Table 5, in Examples 1 to 29, the liquid crystal alignment properties (AC afterimage properties), low-voltage drive, alignment uniformity, white luminance, and response speed were all evaluated as good or fair, indicating a good balance of various properties. Furthermore, the use of a crosslinking agent without an aromatic ring tended to enable the liquid crystal device to be driven at a lower voltage. From these results, it can be said that by forming a liquid crystal alignment film on one of the first and second substrates using a liquid crystal alignment agent for forming a weak anchoring film containing a polymer (P) having a specific substructure, it is possible to obtain a liquid crystal device that has good liquid crystal alignment properties (AC afterimage properties), low-voltage drive, and a good balance of alignment uniformity, white luminance, and response speed.

[0214] In contrast, in Comparative Examples 1 to 5, in which a liquid crystal alignment film was formed on the second substrate using a liquid crystal alignment agent containing a polymer not having a specific partial structure instead of the polymer (P) having a specific partial structure, the white luminance of the liquid crystal element was evaluated as poor. Also, in Comparative Example 6, in which the organic film formed on the second substrate was not subjected to an alignment treatment, the response speed of the liquid crystal element was evaluated as poor. [Explanation of symbols]

[0215] 10... FFS type liquid crystal display element, 11a, 11b... glass substrate, 12... liquid crystal alignment film, 13... top electrode, 14... insulating layer, 15... bottom electrode

Claims

1. A liquid crystal alignment agent for forming a weak anchoring film, which is used to form a weak anchoring liquid crystal alignment film, A liquid crystal aligning agent for forming a weak anchoring film, comprising a polymer (P) having at least one structure selected from the group consisting of a partial structure represented by the following formula (1), a partial structure represented by the following formula (2), a partial structure represented by the following formula (3), a partial structure represented by the following formula (4), an azobenzene structure, a chalcone structure, a coumarin structure, and a chromanone structure. 【Chemistry 1】 (In formula (1), A １ and A ２ are each independently an aromatic ring group. １ and Y ２ are each independently a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 10 carbon atoms. １ represents an oxygen atom or -NR ３ - is. R ３ is a hydrogen atom or a monovalent organic group. n1 is an integer of 0 to 2. When n1 is 2, a plurality of A １ are the same or different. １ " represents a bond to an atom contained in the polymer main chain.) 【Chemistry 2】 (In formula (2), A １ and A ２ are each independently an aromatic ring group. n1 is 0 or 1. Y １ and Y ２ are each independently a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 10 carbon atoms. １ represents an oxygen atom or -NR ３ - is. R ３ is a hydrogen atom or a monovalent organic group. ２ represents a single bond, an oxygen atom, or -NR ４ - is. R ４ is a hydrogen atom or a monovalent organic group. ２ represents an alkanediyl group having 1 to 10 carbon atoms, a fluoroalkanediyl group having 1 to 10 carbon atoms, a divalent aliphatic ring group, or a divalent aromatic ring group. n2 is 0 or 1. Z １ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, -NR ５ R ６ , a nitrile group, a substituted or unsubstituted alkynyl group, an acetyl group, a trifluoromethyl group, or a fluorine atom. ５ and R ６ are each independently an alkyl group having 1 to 16 carbon atoms. １ represents an alkanediyl group having 1 to 10 carbon atoms, or an alkanediyl group having 2 to 10 carbon atoms in which one or more methylene groups are -O-, -S-, -NR ７ -, -CO-, -CO-O- or -CO-NR ７ - is a divalent group in which R ７ is a hydrogen atom or a monovalent organic group. "*" represents a bond. 【Transformation 3】 (In formula (3), A １ and A ２ are each independently an aromatic ring group. １ and Y ２ are each independently a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 10 carbon atoms. １ represents an oxygen atom or -NR ３ - is. R ３ is a hydrogen atom or a monovalent organic group. ２ represents a single bond, an oxygen atom, or -NR ４ - is. R ４ is a hydrogen atom or a monovalent organic group. ２ , n1 and n2 are Y １ and Y ２ at least one of Y is a fluorine atom or an alkyl group having 1 to 4 carbon atoms, or １ and Y ２ are both hydrogen atoms, and A １ and A ２ is an aromatic heterocyclic group, ２ represents an alkanediyl group having 1 to 10 carbon atoms, a fluoroalkanediyl group having 1 to 10 carbon atoms, a divalent aliphatic cyclic group, or a divalent aromatic cyclic group, n1 is 0 or 1, and n2 is 0 or 1. If the above conditions are not satisfied, R ２ is an alkanediyl group having 1 to 10 carbon atoms, n1 is 1, and n2 is 1. Z １ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or —NR ５ R ６ , a nitrile group, a substituted or unsubstituted alkynyl group, an acetyl group, a trifluoromethyl group, or a fluorine atom, and when the above conditions are not satisfied, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, —NR ５ R ６ , a nitrile group, a substituted or unsubstituted alkynyl group, an acetyl group, a trifluoromethyl group, or a fluorine atom. ５ and R ６ are each independently an alkyl group having 1 to 16 carbon atoms. １ represents an alkanediyl group having 1 to 10 carbon atoms, or an alkanediyl group having 2 to 10 carbon atoms in which one or more methylene groups are -O-, -S-, -NR ７ -, -CO-, -CO-O- or -CO-NR ７ - is a divalent group in which R ７ is a hydrogen atom or a monovalent organic group. "*" represents a bond.) 【Chemistry 4】 (In formula (4), A ３ and A ４ are each independently a nitrogen-containing aromatic heterocyclic group. １ " represents a bond to an atom contained in the polymer main chain.)

2. The liquid crystal alignment agent for forming a weak anchoring film according to claim 1, wherein the polymer (P) is at least one selected from the group consisting of an addition polymer, a polyamic acid, a polyamic acid ester, a polyimide, and a polyorganosiloxane.

3. The liquid crystal aligning agent for forming a weak anchoring film according to claim 1 , further comprising a polymer (Q) different from the polymer (P).

4. The liquid crystal alignment agent for forming a weak anchoring film according to claim 3, wherein the polymer (Q) is at least one selected from the group consisting of an addition polymer, a polyamic acid, a polyamic acid ester, a polyimide, and a polyorganosiloxane.

5. The liquid crystal aligning agent for forming a weak anchoring film according to claim 4, wherein the polymer (Q) comprises a polymer (Q1) having at least one of an alkyl group having 5 or more carbon atoms and a cycloalkyl group having 7 or more carbon atoms in a side chain.

6. The liquid crystal aligning agent for forming a weak anchoring film according to claim 5 , wherein the polymer (Q) further comprises a polymer different from the polymer (Q1).

7. The liquid crystal aligning agent for forming a weak anchoring film according to claim 1 , further comprising a crosslinking agent.

8. The liquid crystal aligning agent for forming a weak anchoring film according to claim 7 , wherein the crosslinking agent does not have an aromatic ring.

9. A method for producing a liquid crystal alignment film, comprising forming a weak anchoring liquid crystal alignment film using the liquid crystal aligning agent for forming a weak anchoring film according to any one of claims 1 to 8.

10. A method for manufacturing a liquid crystal element including a pair of substrates consisting of a first substrate and a second substrate, and a liquid crystal layer disposed between the pair of substrates, comprising: A method for manufacturing a liquid crystal element, comprising the steps of applying a liquid crystal alignment agent for forming a weak anchoring film according to any one of claims 1 to 8 to the surface of at least one of the first substrate and the second substrate, and then performing a photoalignment treatment to form a weak anchoring liquid crystal alignment film.

11. forming the weak anchoring liquid crystal alignment film on a surface of one of the first substrate and the second substrate; 11. The method for manufacturing a liquid crystal element according to claim 10, further comprising a step of forming a strong anchoring liquid crystal alignment film having stronger anchoring energy than the weak anchoring liquid crystal alignment film on the surface of one of the first substrate and the second substrate, which is different from the substrate on which the weak anchoring liquid crystal alignment film is formed.

12. the strong anchoring alignment film is a rubbed alignment film, 12. The method for manufacturing a liquid crystal element according to claim 11, wherein in the step of forming the weak anchoring liquid crystal alignment film, a heat treatment is not performed after the exposure for the photo-alignment treatment, or the heat treatment is performed at a temperature of 200°C or less.

13. the strong anchoring alignment film is a photo-alignment film, In the step of forming the strong anchoring alignment film, a heat treatment is performed at a first temperature after exposure for a photo-alignment treatment; 12. The method for manufacturing a liquid crystal element according to claim 11, wherein in the step of forming the weak anchoring liquid crystal alignment film, a heat treatment is not performed after exposure for the photo-alignment treatment, or a heat treatment is performed at a second temperature lower than the first temperature.

14. the first substrate has a pair of electrodes, and the second substrate has no electrodes; forming the strong anchoring liquid crystal alignment film on the surface of the first substrate; The method for manufacturing a liquid crystal device according to claim 11 , wherein the weak anchoring liquid crystal alignment film is formed on a surface of the second substrate.

15. The method for producing a liquid crystal element according to claim 11 , wherein the strong anchoring liquid crystal alignment film contains a polymer having a partial structure represented by the following formula (5) in its main chain: 【Transformation 5】 (In formula (5), B １ is a cyclic group. ２ and B ３ are each independently an aromatic ring group. "*" represents a bond to an atom contained in the polymer main chain.)

16. A method for manufacturing a liquid crystal element including a pair of substrates consisting of a first substrate and a second substrate, and a liquid crystal layer disposed between the pair of substrates, comprising: A step of forming a first liquid crystal alignment film by applying the liquid crystal alignment agent for forming a weak anchoring film according to any one of claims 1 to 8 to a surface of at least one of the first substrate and the second substrate and performing a photoalignment treatment; forming a second liquid crystal alignment film on a surface of one of the first substrate and the second substrate, which is different from the substrate on which the first liquid crystal alignment film is formed; Including, The method for manufacturing a liquid crystal element, wherein the second liquid crystal alignment film contains a polymer having a partial structure represented by the following formula (5) in its main chain: 【Transformation 6】 (In formula (5), B １ is a cyclic group. ２ and B ３ are each independently an aromatic ring group. "*" represents a bond to an atom contained in the polymer main chain.)

17. A method for manufacturing a liquid crystal element including a pair of substrates consisting of a first substrate and a second substrate, and a liquid crystal layer disposed between the pair of substrates, comprising: forming a first liquid crystal alignment film on a surface of one of the first substrate and the second substrate by a photoalignment method; forming a second liquid crystal alignment film by a rubbing method on a surface of one of the first substrate and the second substrate, which is different from the substrate on which the first liquid crystal alignment film is formed; Including, In the step of forming the first liquid crystal alignment film, a heat treatment is not performed after the exposure for the photo-alignment treatment, or the heat treatment is performed at a temperature of 200° C. or less.

18. A method for manufacturing a liquid crystal element including a pair of substrates consisting of a first substrate and a second substrate, and a liquid crystal layer disposed between the pair of substrates, comprising: forming a first liquid crystal alignment film on a surface of the first substrate by a photoalignment method; forming a second liquid crystal alignment film on the surface of the second substrate by a photoalignment method; Including, A method for manufacturing a liquid crystal element, wherein in the step of forming one of the first liquid crystal alignment film and the second liquid crystal alignment film, a heat treatment is performed at a first temperature after exposure for a photo-alignment treatment, and in the step of forming the other liquid crystal alignment film, either no heat treatment is performed after exposure for the photo-alignment treatment or a heat treatment is performed at a second temperature lower than the first temperature.

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