TWI848182B - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal element - Google Patents

Abstract

The present invention provides a liquid crystal alignment agent, a liquid crystal alignment film and a liquid crystal element which have excellent coating properties and can obtain a liquid crystal element with good electrical properties. The present invention provides a liquid crystal alignment agent containing: a polymer P having at least one selected from the group consisting of an amide group, a protected amide group, a urea group and a protected urea group; a cyclic carbonate compound; and a dialkylene glycol monoalkyl ether.

Description

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

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

In recent years, liquid crystal elements are not only used in display devices such as personal computers, LCD TVs, car navigation systems, mobile phones, smart phones, and information displays, but also in a variety of applications such as optical compensation films and dimming films. With this versatility, liquid crystal elements are required to be of higher quality, and improvements in driving methods and element structures, as well as improvements in liquid crystal alignment films, which are one of the components of liquid crystal elements, are being promoted.

In order to further improve the performance of liquid crystal elements, it is proposed to use polyimide having a nitrogen-containing structure such as an amide group (-NH-CO-) as an alignment film material (for example, refer to Patent Document 1). Patent Document 1 discloses that a liquid crystal alignment agent contains polyamide, which is obtained by reacting a tetracarboxylic dianhydride containing 1,2,3,4-cyclobutanetetracarboxylic dianhydride with a diamine compound containing a diamine having an amide group (-NH-CO-). [Prior Art Document]

[Patent document] [Patent document 1] Japanese Patent Publication No. 2009-294274

[Problem to be solved by the invention] Amide groups have high polarity and are not very soluble in the solvent component of the liquid crystal alignment agent. Therefore, the liquid crystal alignment agent prepared with a polymer having a nitrogen-containing structure such as an amide group has poor coating properties on the substrate, and the thickness of the alignment film formed using the liquid crystal alignment agent is sometimes uneven.

The liquid crystal alignment film is generally formed by coating a liquid crystal alignment agent containing a polymer component and a solvent on a substrate laminated with a color filter or a transparent conductive film, and removing the solvent from the coated film. At this time, since the solvent component in the liquid crystal alignment agent penetrates into the lower layer, the low molecular components contained in the lower layer (such as the colored cured film) may be dissolved and mixed into the liquid crystal alignment film or the liquid crystal layer. In this case, there is a concern that the electrical properties of the liquid crystal element will be reduced due to the dissolved substances from the lower layer.

The present invention is made in view of the above-mentioned problem, and one of its purposes is to provide a liquid crystal alignment agent that has excellent coating properties and can obtain a liquid crystal element with good electrical properties. [Technical means to solve the problem]

The present invention adopts the following means to solve the above-mentioned problems.

<1> A liquid crystal alignment agent, comprising: a polymer [P] having at least one selected from the group consisting of an amide group, a protected amide group, a urea group, and a protected urea group; a cyclic carbonate compound; and a dialkylene glycol monoalkyl ether. <2> The liquid crystal alignment agent according to <1>, further comprising a dialkylene glycol dialkyl ester. <3> A liquid crystal alignment film, formed using the liquid crystal alignment agent according to <1> or <2>. <4> A liquid crystal element, comprising the liquid crystal alignment film according to <3>. [Effect of the invention]

The liquid crystal alignment agent of the present invention has excellent coating properties and can obtain a liquid crystal element with good electrical properties.

Hereinafter, each component contained in the liquid crystal alignment agent of the present disclosure and other components arbitrarily prepared as needed will be described. The liquid crystal alignment agent contains a polymer component and a solvent component, and is preferably a liquid polymer composition in which the polymer component is dissolved in the solvent component.

In addition, in this specification, the so-called "alkyl group" means a chain alkyl group, an alicyclic alkyl group and an aromatic alkyl group. The so-called "chain alkyl group" refers to a straight chain alkyl group and a branched alkyl group that do not contain a ring structure in the main chain and are composed only of a chain structure. Among them, it can be saturated or unsaturated. The so-called "alicyclic alkyl group" refers to a alkyl group that contains only an alicyclic hydrocarbon structure as a ring structure and does not contain an aromatic ring structure. Among them, it is not necessary to be composed only of an alicyclic hydrocarbon structure, and a group having a chain structure in a part thereof is also included. The "aromatic hydrocarbon group" refers to a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it is not necessary to be composed of only an aromatic ring structure, and a chain structure or an alicyclic hydrocarbon structure may be contained in part thereof.

<Polymer component><Polymer[P]> The liquid crystal alignment agent disclosed herein contains a polymer [P] having at least one partial structure selected from the group consisting of an amide group, a protected amide group, a urea group, and a protected urea group (hereinafter also referred to as a "specific structure"). The specific structure of the polymer [P] is represented by the following formula (1), for example. [Chemical 1] (In formula (1), ^R1 and ^R2 are each independently a hydrogen atom or a monovalent organic group. m is 0 or 1. "*" indicates a bond to a hydrocarbon group.)

In the formula (1), the monovalent organic group represented by ^R1 and ^R2 is preferably a monovalent alkyl group or a protecting group having 1 to 20 carbon atoms. Examples of the monovalent alkyl group include a monovalent chain alkyl group, an alicyclic alkyl group, and an aromatic alkyl group. Among them, an alkyl group, a cycloalkyl group, or a phenyl group having 1 to 3 carbon atoms is preferred. Here, the protecting group is a functional group that makes the group represented by the formula (1) inert in advance. The "protected amide group" is a group that generates the group "* ¹ -CO-NH-* ¹ " (wherein * ¹ represents a bond to the alkyl group) by the removal of the protecting group. In addition, the "protected urea group" is a group which generates a group "* ² -NH-CO-NH-* ² " (wherein * ² represents a bond with a alkyl group) by the removal of the protecting group.

The protecting group in the formula (1) is preferably a monovalent group that is released by heat or light, and examples thereof include carbamate protecting groups, amide protecting groups, imide protecting groups, and sulfonamide protecting groups. Among them, carbamate protecting groups are preferred in terms of high thermal release, and specific examples thereof include tert-butoxycarbonyl, benzyloxycarbonyl, 1,1-dimethyl-2-halogenated ethoxycarbonyl, allyloxycarbonyl, and 2-(trimethylsilyl)ethoxycarbonyl. Among them, tert-butoxycarbonyl is particularly preferred in terms of excellent thermal release and the ability to reduce the amount of the deprotected portion remaining in the film. ^R1 and ^R2 are preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or a protecting group, and are particularly preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or a tert-butoxycarbonyl group.

Examples of the polymer [P] include polymers having as their main skeleton polyamic acid, polyamic acid ester, polyimide, polysiloxane, polyenamine, polyester, polyamide, polyamide imide, polybenzoxazole precursor, polybenzoxazole, cellulose derivative, polyacetal, and polymers having structural units derived from monomers containing polymerizable unsaturated bonds (hereinafter also referred to as "polymer Q"), etc. In terms of being able to form a liquid crystal alignment film that has affinity with liquid crystals, high mechanical strength and high reliability, the polymer [P] is preferably selected from at least one of the group consisting of polyamic acid, polyamic acid ester, polyimide, polysiloxane, polyamide and polymer Q, and is particularly preferably selected from at least one of the group consisting of polyamic acid, polyamic acid ester and polyimide.

The polymer [P] may have a specific structure in the main chain and in either the side chain. From the viewpoint of making the electrical properties of the liquid crystal element more excellent, the polymer [P] preferably has a specific structure in the main chain. In addition, the so-called "having a specific structure in the main chain" means including the case where the specific structure is only in the main chain, and the case where the specific structure is in the main chain and the side chain. Here, the so-called "main chain" refers to the part of the "trunk" containing the longest atomic chain in the polymer. In addition, the part of the "trunk" is allowed to contain a ring structure. Therefore, the so-called "having a specific structure in the main chain" means that the specific structure constitutes a part of the main chain. The so-called "side chain" refers to the part branching from the "trunk" of the polymer.

As a method for obtaining a polymer having a specific structure, a method of polymerizing using a monomer having a specific structure can be cited. In this case, in the polymer [P], the content of the structural unit derived from the monomer having a specific structure is preferably 5 mol% or more, more preferably 10 mol% or more, further preferably 15 mol% or more, and particularly preferably 20 mol% or more relative to the total amount of monomer units possessed by the polymer [P]. In addition, the content of the structural unit derived from the monomer having a specific structure is preferably 90 mol% or less, more preferably 80 mol% or less, and further preferably 70 mol% or less relative to the total amount of monomer units possessed by the polymer [P].

･Specific group A The polymer [P] preferably further has at least one group selected from the group consisting of a group having a polymerizable carbon-carbon unsaturated bond, a photoinitiator group, and a photoalignment group (hereinafter also referred to as "specific group A"). By having such a specific group A, a more stable liquid crystal alignment film can be formed, and a liquid crystal alignment film that can obtain a liquid crystal element showing excellent electrical characteristics can be formed, which is preferred in this respect.

In the specific group A, the group having a polymerizable carbon-carbon unsaturated bond is preferably a functional group that can be polymerized by heat or light. Specific examples of the group having a polymerizable carbon-carbon unsaturated bond include: (meth)acryloyl, vinyl, allyl, vinylphenyl, maleimide, vinyloxy, ethynyl, etc. Among them, in terms of high reactivity based on heat, (meth)acryloyl, vinyl, allyl, ethynyl or vinylphenyl is preferred, and (meth)acryloyl is more preferred.

In the polymer [P], the content of the group having a polymerizable carbon-carbon unsaturated bond is preferably 1 mol% or more, more preferably 5 mol% or more, and further preferably 10 mol% or more, relative to the total amount of monomer units possessed by the polymer [P]. In addition, the content of the group having a polymerizable carbon-carbon unsaturated bond is preferably 60 mol% or less, more preferably 50 mol% or less, relative to the total amount of monomer units possessed by the polymer [P].

The photoinitiator group is a site that generates polymerization initiation ability by light or a site that has a photosensitizing effect, and is a group having a structure after removing one or more hydrogen atoms from the photoinitiator. Here, the photoinitiator refers to a compound that can initiate polymerization of a polymerizable component by irradiation with radiation such as visible light, ultraviolet light, far ultraviolet light, electron beam, X-rays, etc. The photoinitiator group possessed by the polymer [P] is preferably a group having a structure after removing hydrogen atoms from a free radical polymerization initiator that can generate free radicals by light irradiation, specifically, preferably a group having an acetophenone structure, an oxime ester structure, a diphenylformyl structure, a benzoin structure, a benzophenone structure, a phenylalkyl ketone structure or an acylphosphine oxide structure. Among them, the photoinitiator group is preferably a group having an alkylphenone structure or an acetophenone structure.

As further specific examples of the photoinitiator group, for example, groups having a structure obtained by removing a hydrogen atom from the following substances can be cited: 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-phenyl-propane-1-one, phenyl 2-(methyl)acryloyloxy-2-propyl ketone, 4-isopropylphenyl 2-(methyl)acryloyloxy-2-propyl ketone, 4-(2-(methyl)acryloyloxyethoxy)-benzoin, 4-(methyl)acryloyloxyphenyl 2-(methyl)acryloyloxy-2-propyl ketone, 4-(methyl)acryloyloxybenzophenone, and the like.

In the polymer [P], the content of the photoinitiator group is preferably 1 mol% or more, more preferably 3 mol% or more, and further preferably 5 mol% or more, relative to the total amount of monomer units in the polymer [P]. In addition, the content of the photoinitiator group is preferably 50 mol% or less, more preferably 40 mol% or less, relative to the total amount of monomer units in the polymer [P].

The photoalignment group is a functional group that imparts anisotropy to the film through a photoisomerization reaction or a photodimerization reaction, a photodecomposition reaction, or a photoFries rearrangement reaction caused by light irradiation. Specific examples of the photoalignment group include: an azobenzene-containing group including azobenzene or its derivatives as a basic skeleton, a cinnamic acid structure-containing group including cinnamic acid or its derivatives as a basic skeleton, a chalcon-containing group including chalcon or its derivatives as a basic skeleton, a benzophenone-containing group including benzophenone or its derivatives as a basic skeleton, a coumarin-containing group including coumarin or its derivatives as a basic skeleton, and a cyclobutane-containing structure including cyclobutane or its derivatives as a basic skeleton. Among them, a group containing a cinnamic acid structure is preferred in terms of high sensitivity to light, and examples thereof include a group having a partial structure represented by the following formula (6). (In formula (6), R ²¹ and R ²² are independently a hydrogen atom, a fluorine atom, a cyano group, an alkyl group having 1 to 3 carbon atoms, or a fluoroalkyl group having 1 to 3 carbon atoms, and R ²³ is an alkyl group having 1 to 10 carbon atoms, an alkoxy group, a fluoroalkyl group or a fluoroalkoxy group, a fluorine atom or a cyano group. k is an integer of 0 to 4. When k is 2 or more, a plurality of R ²³ are the same group or different groups. "*" represents a bonding bond.)

In the structure represented by the formula (6), from the viewpoint of further improving the photoreactivity, R ²¹ and R ²² are preferably both hydrogen atoms, or one of them is a hydrogen atom and the other (preferably R ²² ) is an alkyl group having 1 to 3 carbon atoms. R ²³ is preferably a fluorine atom, a cyano group, or an alkyl group having 1 to 5 carbon atoms, more preferably a fluorine atom, a cyano group, or an alkyl group having 1 to 3 carbon atoms. k is preferably 0 to 2, more preferably 0 or 1.

In terms of more appropriately controlling the pretilt angle of the obtained liquid crystal element, one of the two bonding bonds "*" in the formula (6) is preferably bonded to an alkyl group, an alkoxy group, a fluoroalkyl group, a fluoroalkoxy group, a cyano group-containing alkyl group or a cyano group-containing alkoxy group having 3 to 20 carbon atoms, or a group having at least one of a benzene ring and a cyclohexane ring.

In the polymer [P], the content of the photo-alignment group is preferably 1 mol% or more, more preferably 5 mol% or more, and further preferably 10 mol% or more relative to the total amount of the monomer units possessed by the polymer [P]. In addition, the content of the photo-alignment group is preferably 60 mol% or less, more preferably 50 mol% or less relative to the total amount of the monomer units possessed by the polymer [P].

･Specific group B The polymer [P] preferably also has at least one group selected from the group consisting of a tertiary amine structure, a protected amino group, and a nitrogen-containing aromatic heterocyclic group (hereinafter also referred to as "specific group B"). By having such a specific group B, a liquid crystal element showing more excellent electrical properties can be obtained, which is preferred in this respect.

In the specific group B, the tertiary amine structure is preferably a partial structure represented by the following formula (7). (In formula (7), ^R51 is a divalent hydrocarbon group. ^R52 and ^R53 represent that ^R52 is a divalent hydrocarbon group and ^R53 is a monovalent hydrocarbon group, or that ^R52 and ^R53 are bonded to each other and form a ring structure together with the nitrogen atom to which ^R52 and ^R53 are bonded. "*" represents a bonding bond.)

In the above formula (7), examples of the divalent hydrocarbon group of ^R51 and ^R52 include an alkanediyl group, a cyclohexylene group, a phenylene group, and the like. Examples of the monovalent hydrocarbon group of ^R53 include an alkyl group, a cyclohexyl group, a phenyl group, and the like. Examples of the ring structure formed by ^R52 and ^R53 bonding to each other and together with the nitrogen atom to which ^R52 and ^R53 bond include a piperidine structure, a piperazine structure, a pyrrolidine structure, a hexamethyleneimine structure, and the like.

Among the protected amino groups, the amino group is protected by a protecting group, and the protecting group is preferably detached by heat to generate a primary amino group or a secondary amino group. In addition, the primary amino group or the secondary amino group generated by the detachment of the protecting group is bonded to a alkyl group. The protecting group is preferably a group that is detached by heat, for example, carbamate protecting groups, amide protecting groups, imide protecting groups, sulfonamide protecting groups, etc. Among them, the protecting group is preferably a tert-butyloxycarbonyl group in terms of high thermal detachability and the ability to reduce the residual amount of the deprotected part in the film.

The nitrogen-containing aromatic heterocyclic group is an n-valent group obtained by removing n hydrogen atoms from the ring part of the nitrogen-containing aromatic heterocyclic group. The nitrogen-containing aromatic heterocyclic group may be an aromatic ring containing one or more nitrogen atoms in the ring skeleton. In addition, as a hetero atom, it may contain only a nitrogen atom, or may contain a nitrogen atom and a hetero atom other than a nitrogen atom (oxygen atom, sulfur atom, etc.).

Specific examples of the heterocyclic ring constituting the nitrogen-containing aromatic heterocyclic group include a pyrrole ring, an imidazole ring, a pyrazole ring, a triazole ring, a pyridine ring, a pyrimidine ring, a oxadiazole ring, a pyrazine ring, an indole ring, a benzimidazole ring, a purine ring, a quinoline ring, an isoquinoline ring, a naphthyridine ring, Quinoline ring, phthalazine ring, triazine ring, azepine ring, diazepine ring, acridine ring, phenanthrazine ring, phenanthroline ring, oxazole ring, thiazole ring, oxazole ring, thiadiazole ring, benzothiazole ring, phenothiazine ring, oxadiazole ring, etc. In the nitrogen-containing aromatic heterocyclic group, a substituent may be introduced into the ring part. Examples of the substituent include halogen atoms, alkyl groups, alkoxy groups, etc. Among them, the nitrogen-containing aromatic heterocyclic group is preferably a group obtained by removing a hydrogen atom from a ring portion of a pyrrole ring, an imidazole ring, a pyrazole ring, a triazole ring, a pyridine ring, a pyrimidine ring, an oxazine ring or a pyrazine ring.

In polymer [P], the content of specific group B is preferably 1 mol% or more, more preferably 5 mol% or more, and further preferably 10 mol% or more relative to the total amount of monomer units possessed by polymer [P]. In addition, the content of specific group B is preferably 60 mol% or less, more preferably 50 mol% or less relative to the total amount of monomer units possessed by polymer [P]. In addition, the specific group B possessed by polymer [P] may be only one kind or two or more kinds.

Next, preferred examples of the polymer [P] are described in detail. ＜Polyamide＞ When the polymer [P] is polyamide, the polyamide (hereinafter also referred to as "polyamide [P]") can be obtained by reacting tetracarboxylic dianhydride with a diamine compound. Methods for obtaining a polymer having a specific structure include: (1) a method of polymerizing using tetracarboxylic dianhydride having a specific structure, (2) a method of polymerizing using a diamine having a specific structure (hereinafter also referred to as "specific diamine"), etc. Among them, method (2) is preferred in terms of high freedom of selection of monomers.

(Tetracarboxylic dianhydride) Examples of tetracarboxylic dianhydrides used in the synthesis of polyamide [P] include aliphatic tetracarboxylic dianhydrides, alicyclic tetracarboxylic dianhydrides, aromatic tetracarboxylic dianhydrides, and the like. As specific examples thereof, aliphatic tetracarboxylic dianhydrides include 1,2,3,4-butanetetracarboxylic dianhydride, etc.; Alicyclic tetracarboxylic dianhydrides include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 5-(2,5-dioxotetrahydrofuran-3-yl)-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 5-(2,5-dioxotetrahydrofuran-3-yl)-8-methyl-3a,4,5,9b-tetrahydronaphtho[1 ,2-c] furan-1,3-dione, 2,4,6,8-tetracarboxylic biscyclo[3.3.0]octane-2:4,6:8-dianhydride, cyclopentanetetracarboxylic dianhydride, cyclohexanetetracarboxylic dianhydride, etc.; aromatic tetracarboxylic dianhydride includes pyromellitic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, ethylene glycol ditrimellitate, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 4,4'-carbonyldiphthalic anhydride, etc. In addition to the above tetracarboxylic dianhydrides, tetracarboxylic dianhydrides described in Japanese Patent Laid-Open No. 2010-97188 can also be used. As tetracarboxylic dianhydrides, one type can be used alone or two or more types can be used in combination.

As the tetracarboxylic dianhydride used in the synthesis of the polyamide [P], in terms of obtaining a polymer [P] having higher solubility in a solvent, it is preferred that the tetracarboxylic dianhydride contains at least one compound selected from the group consisting of aliphatic tetracarboxylic dianhydrides and alicyclic tetracarboxylic dianhydrides, more preferably contains alicyclic tetracarboxylic dianhydride, and further preferably contains alicyclic tetracarboxylic dianhydride having at least one ring structure selected from the group consisting of a cyclobutane ring, a cyclopentane ring and a cyclohexane ring. The usage ratio of aliphatic tetracarboxylic dianhydride and alicyclic tetracarboxylic dianhydride (total amount when two or more are included) is preferably 20 mol% or more, more preferably 40 mol% or more, and further preferably 50 mol% or more, relative to the total amount of tetracarboxylic dianhydride used in the synthesis of polyamide [P].

(Diamine compound) ･Specific diamines Examples of diamine compounds used in the synthesis of polyamide include aliphatic diamines, alicyclic diamines, aromatic diamines, and diaminoorganosiloxanes. The specific diamine is preferably an aromatic diamine, and specifically, a compound represented by the following formula (5A) and a compound represented by the following formula (5B) can be mentioned. [Chemistry 4] (In formula (5A), ^R10 , ^R11 and ^R12 are each independently a single bond, a divalent hydrocarbon group having 1 to 20 carbon atoms, or a divalent group having 2 to 20 carbon atoms with -O- between carbon-carbon bonds. j is an integer of 1 to 3. When j = 2 or 3, ^R11 does not form a single bond. ^R13 and ^R14 are each independently a monovalent organic group having 1 to 5 carbon atoms. p1 and p2 are each independently an integer of 0 to 2. ^R1 , ^R2 and m have the same meanings as in formula (1).) [Chemistry 5] (In formula (5B), ^L3 is a single bond or a divalent linking group, and ^R17 is a monovalent organic group having 1 to 40 carbon atoms. m1 and m2 are each independently 0 or 1. However, m1 and m2 are not simultaneously 0. ^R1 and ^R2 have the same meanings as in formula (1).)

In the formula (5A), from the viewpoint of improving the electrical properties of the liquid crystal element, the divalent hydrocarbon group represented by R ¹⁰ , R ¹¹ and R ¹² is preferably a divalent chain hydrocarbon group or an alicyclic hydrocarbon group, more preferably a divalent chain hydrocarbon group, and further preferably an alkanediyl group. When the divalent hydrocarbon group represented by R ¹⁰ , R ¹¹ and R ¹² is an alkanediyl group, the carbon number of R ¹⁰ , R ¹¹ and R ¹² is preferably 1 to 10, more preferably 1 to 6. When ^R10 , ^R11 and ^R12 are divalent groups having 2 to 20 carbon atoms and having -O- between carbon-carbon bonds, the divalent group is preferably ^-R15- ( ^OR16 )r- (wherein ^R15 and ^R16 are each independently an alkanediyl group, and r is an integer of 1 to 3). ^R13 and ^R14 are preferably alkyl groups having 1 to 5 carbon atoms, more preferably methyl or ethyl groups. p1 and p2 are preferably 0 or 1. j is preferably 1 or 2.

In the formula (5B), the divalent linking group of ^L3 is preferably an alkanediyl group having 1 to 5 carbon atoms, and more preferably an alkanediyl group having 1 to 3 carbon atoms. Examples of the monovalent organic group of ^R17 include a monovalent alkyl group having 1 to 40 carbon atoms, a group containing a heteroatom between the carbon-carbon bonds of the alkyl group, and a group having a heterocyclic group. Among them, ^R17 is preferably a monovalent aromatic alkyl group having 6 to 20 carbon atoms or a monovalent group having a nitrogen-containing aromatic heterocyclic ring.

As specific examples of specific diamines, the compound represented by the formula (5A) includes compounds represented by the following formulas (5-1) to (5-17), etc.; the compound represented by the formula (5B) includes compounds represented by the following formulas (5-18) to (5-31), etc. In addition, by using compounds represented by the following formulas (5-18) to (5-22), (5-28), (5-29), and (5-31), a polymer [P] having a nitrogen-containing aromatic heterocyclic group as the specific group B can be obtained. [Chemistry 6] [Chemistry 7] (In the formula, "TMS" represents trimethoxysilyl.) [Chemistry 8]

･Other diamines The diamine compound used in the synthesis of polyamide [P] may be only the specific diamine, or may be used in combination with the specific diamine and a diamine different from the specific diamine (hereinafter also referred to as "other diamine"). Examples of the other diamines include aliphatic diamines, alicyclic diamines, aromatic diamines, diaminoorganosiloxanes, and the like.

Specific examples of other diamines include p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4-aminophenyl-4-aminobenzoate, 4,4'-diaminoazobenzene, 3,5-diaminobenzoic acid, 1,5-bis(4-aminophenoxy)benzene, 1,2-bis(4-aminophenoxy)ethane, 1,3-bis(4-aminophenoxy)propane, 1,6-bis(4-aminophenoxy)hexane, bis[2-(4-aminophenyl)ethyl]hexanediacid, 4,4'-diaminodiphenyl ether, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2, Main chain diamines such as 2-bis(4-aminophenyl)hexafluoropropane, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-diaminodiphenylamine, 1,5-bis(4-aminophenyl)benzene, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-(phenylene diisopropylidene)bisaniline, 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, m-xylene diamine, hexamethylene diamine, and 4,4'-methylenebis(cyclohexylamine); Dodecyloxy-2,4-diaminobenzene, pentadecyloxy-2,4-diaminobenzene, hexadecyloxy-2,4-diaminobenzene, octadecyloxy-2,4-diaminobenzene, pentadecyloxy-2,5-diaminobenzene, octadecyloxy-2,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, 3,5-diamino Side chain diamines such as cholesteryl benzoate, lanostanyl 3,5-diaminobenzoate, 3,6-bis(4-aminobenzyloxy)cholestane, 3,6-bis(4-aminophenoxy)cholestane, 4-(4'-trifluoromethoxybenzyloxy)cyclohexyl-3,5-diaminobenzoate, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-butylcyclohexane, 3,5-diaminobenzoic acid = 5ξ-cholestane-3-yl ester, and compounds represented by the following formula (E-1), etc., [Chemistry 9] (In formula (E-1), X ^I and X ^II are each independently a single bond, -O-, *-COO- or *-OCO- (where "*" represents a bond to X ^I ), R ^I is an alkanediyl group having 1 to 3 carbon atoms, R ^II is a single bond or an alkanediyl group having 1 to 3 carbon atoms, a is 0 or 1, b is an integer of 0 to 2, c is an integer of 1 to 20, and d is 0 or 1. Wherein a and b are not 0 at the same time.) Examples of the compound represented by formula (E-1) include compounds represented by the following formulas (E-1-1) to (E-1-4). [Chemistry 10]

By using a diamine having a specific group A as another diamine, a polyamide [P] having a specific group A can be produced, and by using a diamine having a specific group B, a polyamide [P] having a specific group B can be produced. Specific examples of the diamine having a specific group A include compounds represented by the following formulas (a-1) to (a-11), respectively. Specific examples of diamines having a specific group B include 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminooxazole, N-methyl-3,6-diaminooxazole, N-ethyl-3,6-diaminooxazole, N-phenyl-3,6-diaminooxazole, 3,6-diaminoacridine, compounds represented by the above formulas (5-18) to (5-22), (5-28), (5-29) and (5-31), and compounds represented by the following formulas (b-1) to (b-18). [Chemistry 11] (In the formula, ^L2 is a divalent linking group.) [Chemistry 12] (In the formula, R ⁴⁰ is an alkyl group having 1 to 20 carbon atoms. L ¹ is a divalent linking group.) [Chemical 13] [Chemistry 14]

When synthesizing polyamine [P], in terms of being able to improve the coating properties of the liquid crystal alignment agent and the electrical properties of the liquid crystal element in a well-balanced manner, the specific diamine is preferably used in an amount of 5 mol% or more, more preferably 10 mol% or more, further preferably 15 mol% or more, and particularly preferably 20 mol% or more, relative to the total amount of the diamine compound used in the synthesis of polyamine [P]. In addition, from the perspective of obtaining the effect of performance improvement brought about by the use of other diamines, the specific diamine is preferably used in an amount of 90 mol% or less, more preferably 80 mol% or less, and further preferably 70 mol% or less. As the specific diamine, one kind may be used alone or two or more kinds may be used in combination.

(Synthesis of polyamide) Polyamide [P] can be obtained by reacting the tetracarboxylic dianhydride and the diamine compound as required together with a molecular weight modifier. In the synthesis reaction of polyamide [P], the ratio of the tetracarboxylic dianhydride to the diamine compound is preferably such that the anhydride group of the tetracarboxylic dianhydride is 0.2 to 2 equivalents relative to 1 equivalent of the amino group of the diamine compound. Examples of molecular weight modifiers include: 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 molecular weight modifier is preferably used in an amount of 20 parts by mass or less relative to a total of 100 parts by mass of the tetracarboxylic dianhydride and the diamine compound used.

The synthesis reaction of polyamine [P] is preferably carried out in an organic solvent. The reaction temperature is preferably -20°C to 150°C, and the reaction time is preferably 0.1 hour to 24 hours. Examples of the organic solvent used in the reaction include aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons, and the like. As a specific example, it is preferred to use one or more selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethylsulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphatiamide, metacresol, dimethylphenol and halogenated phenol as the reaction solvent, or use a mixture of one or more of them with other organic solvents (such as butyl solvent, diethylene glycol diethyl ether, etc.). The amount of organic solvent used (a) is preferably set to an amount such that the total amount of tetracarboxylic dianhydride and diamine (b) is 0.1 mass% to 50 mass% relative to the total amount (a+b) of the reaction solution. In the above manner, a polymer solution in which polyamide [P] is dissolved is obtained. The polymer solution can be used directly for preparing the liquid crystal alignment agent, or can be used for preparing the liquid crystal alignment agent after the polyamine [P] contained in the polymer solution is separated.

<Polyamide> When the polymer [P] is a polyamide, the polyamide (hereinafter also referred to as "polyamide [P]") can be obtained, for example, by the following methods: [I] a method of reacting a polyamide [P] with an esterifying agent; [II] a method of reacting a tetracarboxylic acid diester with a diamine compound; [III] a method of reacting a tetracarboxylic acid diester dihalide with a diamine compound. The polyamide [P] may have only an amide structure or may be a partially esterified product in which an amide structure and an amide structure coexist. Among the above [II] and [III], it is preferred to react a tetracarboxylic acid derivative with a diamine compound containing a specific diamine. The reaction solution obtained by dissolving polyamic acid ester [P] may be directly used for the preparation of the liquid crystal alignment agent, or the polyamic acid ester [P] contained in the reaction solution may be separated and then used for the preparation of the liquid crystal alignment agent.

<Polyimide> When the polymer [P] is a polyimide, the polyimide (hereinafter also referred to as "polyimide [P]") can be obtained, for example, by subjecting the polyamine [P] synthesized in the above manner to dehydration and ring closure and imidization. The polyimide [P] may be a completely imidized product in which all the amide structures of the polyamine [P] as a precursor thereof are dehydrated and ring closed, or a partially imidized product in which only a part of the amide structure is dehydrated and ring closed, so that the amide structure and the imide ring structure coexist. The imidization rate of the polyimide [P] is preferably 20% to 99%, more preferably 30% to 90%. In addition, the imidization rate is expressed as a percentage of the number of imide ring structures relative to the total number of amide structures and imide ring structures of the polyimide. Here, a part of the imide ring may be an isoimide ring.

The dehydration and ring closure of polyamine [P] is preferably carried out by the following method: dissolving polyamine [P] in an organic solvent, adding a dehydrating agent and a dehydration and ring closure catalyst to the solution, and heating as needed. In the method, as a dehydrating agent, for example, an anhydride such as acetic anhydride, propionic anhydride, trifluoroacetic anhydride, etc. can be used. The amount of the dehydrating agent used is preferably set to 0.01 mol to 20 mol relative to 1 mol of the amide structure of polyamine [P]. As a dehydration and ring closure catalyst, for example, a tertiary amine such as pyridine, coltidine, dimethylpyridine, triethylamine, etc. can be used. The amount of the dehydration ring-closing catalyst used is preferably set to 0.01 mol to 10 mol relative to 1 mol of the dehydrating agent used. As the organic solvent used in the dehydration ring-closing reaction, the organic solvent exemplified as the organic solvent used in the synthesis of polyamide [P] can be listed. The reaction temperature of the dehydration ring-closing reaction is preferably 0°C to 180°C. The reaction time is preferably 1.0 hour to 120 hours. In addition, the reaction solution containing polyimide [P] can be directly used for the preparation of a liquid crystal alignment agent, or it can be used for the preparation of a liquid crystal alignment agent after the polyimide [P] is separated.

Regarding the solution viscosity of the polymer [P] used in the preparation of the liquid crystal alignment agent, when a solution with a concentration of 10 mass % is prepared, it is preferably 10 mPa·s to 800 mPa·s, and more preferably 15 mPa·s to 500 mPa·s. In addition, the solution viscosity (mPa·s) is a value measured at 25°C using an E-type rotational viscometer for a 10 mass % polymer solution prepared using a good solvent for the polymer [P] (for example, γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

The weight average molecular weight (Mw) of the polymer [P] measured by gel permeation chromatography (GPC) in terms of polystyrene is preferably 1,000 to 500,000, more preferably 2,000 to 300,000. In addition, the molecular weight distribution (Mw/Mn) represented by the ratio of Mw to the number average molecular weight (Mn) in terms of polystyrene measured by GPC is preferably 7 or less, more preferably 5 or less. When preparing a liquid crystal alignment agent, the polymer [P] may be used alone or in combination of two or more.

The liquid crystal alignment agent disclosed in the present invention may also contain polymers other than polymer [P] (hereinafter also referred to as "other polymers") as polymer components. The other polymers may be polymers without a specific structure, and there is no particular limitation on the main skeleton. Examples of other polymers include polymers having a main skeleton of polyamic acid, polyamic acid ester, polyimide, polysiloxane, polyester, polyenamine, polyurea, polyamide, polyamide imide, polybenzoxazole precursor, polybenzoxazole, cellulose derivative, polyacetal, polymers having structural units derived from monomers containing polymerizable unsaturated bonds, and the like.

For example, when the polymer [P] is at least one selected from the group consisting of polyamine, polyamic acid ester and polyimide, polyorganosiloxane may be formulated as the other polymer. In this case, functional groups such as photoalignment groups or pre-tilt angle-endowing groups are introduced into the side chains of the polyorganosiloxane so that the functional groups are included in the liquid crystal alignment agent together with the polymer [P]. The functional groups of the polyorganosiloxane can be used to impart the desired properties to the liquid crystal alignment film. When the liquid crystal alignment agent contains other polymers, the content of the other polymers is preferably less than 30% by mass, and more preferably less than 20% by mass, relative to the total amount of the polymer [P] and the other polymers. The other polymers may be used alone or in combination of two or more.

《Solvent component》 The liquid crystal alignment agent disclosed in the present invention contains a cyclic carbonate compound and a dialkylene glycol monoalkyl ether. By using a cyclic carbonate compound and a dialkylene glycol monoalkyl ether in combination as the solvent component of the liquid crystal alignment agent containing the polymer [P], a liquid crystal alignment agent showing good coating properties can be obtained, and a liquid crystal element with a sufficiently high voltage retention rate can be obtained.

<Cyclic carbonate compound> The cyclic carbonate compound may be any compound having a carbonate structure (-O-CO-O-) in the cyclic skeleton, and the number of ring members and the presence or absence of a substituent are not particularly limited. As the cyclic carbonate compound, a compound represented by the following formula (2) can be preferably used. [Chemical 15] (In formula (2), R ³ to R ⁶ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 5 carbon atoms. n is an integer of 1 to 5. When n is 2 or more, a plurality of R ⁵ and a plurality of R ⁶ in the formula each independently have the above definition.)

In the formula (2), the monovalent alkyl group having 1 to 5 carbon atoms represented by R ³ to R ⁶ is preferably a monovalent linear or branched alkyl group having 1 to 5 carbon atoms. Specific examples thereof include alkyl groups having 1 to 5 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, and n-pentyl; alkenyl groups having 2 to 5 carbon atoms, such as vinyl and allyl; and alkynyl groups having 2 to 5 carbon atoms, such as ethynyl and prop-2-yn-1-yl. R ³ to R ⁶ are preferably a hydrogen atom or a alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom or a alkyl group having 1 or 2 carbon atoms, and further preferably a hydrogen atom, a methyl, an ethyl, or a vinyl group. n is preferably 1 to 4, more preferably 1 to 3, and further preferably 1 or 2. In the compound represented by the formula (2), the number of substituents in the ring portion (that is, the number of groups in R ³ to R ⁶ that are monovalent hydrocarbon groups having 1 to 5 carbon atoms) is preferably 0 to 3, more preferably 0 to 2.

Specific examples of the cyclic carbonate compound include ethyl carbonate, propyl carbonate, 1,2-butyl carbonate, 2,3-butyl carbonate, vinyl ethyl carbonate, 4-propyl-1,3-dioxacyclopentane-2-one, 1,3-dioxane-2-one, 4-methyl-1,3-dioxane-2-one, 4-ethyl-1,3-dioxane-2-one, 4,6-dimethyl-1,3-dioxane-2-one, etc. As the cyclic carbonate compound, one kind may be used alone, or two or more kinds may be used in combination. Among them, the cyclic carbonate compound is preferably at least one selected from the group consisting of ethyl carbonate, propyl carbonate, 1,2-butyl carbonate, 2,3-butyl carbonate, vinyl ethyl carbonate and 1,3-dioxane-2-one.

In the liquid crystal alignment agent, from the viewpoint of improving the coating property of the liquid crystal alignment agent and the electrical properties of the liquid crystal element with good balance, the content ratio of the cyclic carbonate compound relative to the total amount of the solvent contained in the liquid crystal alignment agent is preferably 0.5 mass % or more. The content ratio of the cyclic carbonate compound is more preferably 2 mass % or more, and further preferably 3 mass % or more, and particularly preferably 5 mass % or more. In addition, from the viewpoint, the content ratio of the cyclic carbonate compound is preferably 50 mass % or less, more preferably 40 mass % or less, and further preferably 30 mass % or less, and particularly preferably 20 mass % or less.

<Dialkanediol monoalkyl ether> Dialkanediol monoalkyl ether can be represented by the following formula (3). (In formula (3), ^R7 is an alkyl group having 1 to 4 carbon atoms. a1 and a2 are each independently an integer of 1 to 4.)

In the formula (3), ^R7 is preferably a linear chain, and is particularly preferably a linear alkyl group having 1 to 3 carbon atoms. a1 and a2 are preferably 1 to 3, and more preferably 2 or 3. Specific examples of dialkylene glycol monoalkyl ethers include dimethylene glycol monomethyl ether, dimethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, and dipropylene glycol mono-n-butyl ether. In addition, as dialkylene glycol monoalkyl ethers, one kind alone or two or more kinds in combination may be used.

In the liquid crystal alignment agent, from the viewpoint of improving the coating property of the liquid crystal alignment agent and the electrical properties of the liquid crystal element in a well-balanced manner, the content of the dialkylene glycol monoalkyl ether is preferably 1% by mass or more relative to the total amount of the solvent contained in the liquid crystal alignment agent. The content of the dialkylene glycol monoalkyl ether is more preferably 5% by mass or more, further preferably 10% by mass or more, and particularly preferably 15% by mass or more. In addition, from the above viewpoint, the content of the dialkylene glycol monoalkyl ether is preferably 70% by mass or less, more preferably 60% by mass or less, further preferably 50% by mass or less, and particularly preferably 40% by mass or less.

<Dialkylene glycol dialkyl ether> The liquid crystal alignment agent disclosed in the present invention preferably contains a cyclic carbonate compound and a dialkylene glycol monoalkyl ether, as well as a dialkylene glycol dialkyl ether. By using a dialkylene glycol dialkyl ether in combination, the liquid crystal alignment agent can have better coating properties (printing properties). In addition, the intermixing effect with the lower layer of the liquid crystal alignment film is highly suppressed, and the electrical properties of the obtained liquid crystal element can be improved. This is suitable in this respect. The dialkylene glycol dialkyl ether can be represented by the following formula (4). [Chemical 17] (In formula (4), ^R8 and ^R9 are each independently an alkyl group having 1 to 4 carbon atoms. b1 and b2 are each independently an integer of 1 to 4.)

In the formula (4), ^R8 and ^R9 are preferably linear, more preferably linear alkyl groups having 1 to 3 carbon atoms, and particularly preferably methyl or ethyl. b1 and b2 are preferably 1 to 3, more preferably 2 or 3. Specific examples of dialkylene glycol dialkyl ethers include dimethylene glycol dimethyl ether, dimethylene diethyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, dipropylene glycol dimethyl ether, dipropylene glycol methyl ethyl ether, dipropylene glycol diethyl ether, dipropylene glycol dipropyl ether, and dipropylene glycol di-n-butyl ether. As dialkylene glycol dialkyl ethers, one kind alone or two or more kinds in combination may be used.

From the viewpoint of improving the coating property of the liquid crystal alignment agent and the electrical properties of the liquid crystal element in a well-balanced manner, the content of the dialkylene glycol dialkyl ether is preferably 1% by mass or more relative to the total amount of the solvent contained in the liquid crystal alignment agent. The content of the dialkylene glycol dialkyl ether is more preferably 5% by mass or more, further preferably 10% by mass or more, and particularly preferably 15% by mass or more. In addition, from the above viewpoint, the content of the dialkylene glycol dialkyl ether is preferably 70% by mass or less, more preferably 60% by mass or less, further preferably 50% by mass or less, and particularly preferably 40% by mass or less.

When a dialkylene glycol monoalkyl ether and a dialkylene glycol dialkyl ether are used as the solvent component, the ratio (D1/D2) of the dialkylene glycol monoalkyl ether (D1) to the dialkylene glycol dialkyl ether (D2) is preferably in the range of 80/20 to 20/80 in terms of mass ratio, more preferably in the range of 70/30 to 30/70, further preferably in the range of 65/35 to 35/65, and particularly preferably in the range of 60/40 to 40/60, from the viewpoint of further enhancing the effect of improving the coating properties.

As the solvent, only cyclic carbonate compounds and dialkylene glycol monoalkyl ethers may be used, or only cyclic carbonate compounds, dialkylene glycol monoalkyl ethers and dialkylene glycol dialkyl ethers may be used, but a solvent different from the cyclic carbonate compounds, dialkylene glycol monoalkyl ethers and dialkylene glycol dialkyl ethers (hereinafter also referred to as "other solvents") may be further contained in the mixed solvent thereof. As other solvents, known solvents used in the preparation of liquid crystal alignment agents may be used. As specific examples of other solvents, solvents that can improve the solubility and leveling properties of polymers (hereinafter also referred to as "first solvents") and solvents having good wetting and spreading properties (hereinafter also referred to as "second solvents") may be listed.

As specific examples thereof, the first solvent may include: N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, γ-butyrolactam, N,N-dimethylformamide, N,N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone, diisobutyl ketone, 1,3-dimethyl-2-imidazolidinone, etc.; The second solvent may include: methanol, ethanol, propanol, butanol, pentanol, 3-methyl-1-butanol , 1-hexanol, 2-hexanol, heptanol, phenol, cyclohexanol, methylcyclohexanol, diacetone alcohol, propane-1,2-diol, 3-methoxy-1-butanol and other alcohol solvents; ethylene glycol monomethyl ether, ethylene glycol monobutyl ether (butyl solvent), propylene glycol monobutyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol n-propyl ether, ethylene glycol isopropyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether (PGME), diisoamyl ether and other ether solvents; ethyl acetate, ethyl acetate, propyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, tert-butyl acetate, 3-methoxybutyl acetate, methyl acetylacetate, ethyl acetylacetate, ethyl propionate, n-butyl propionate, methyl lactate, ethyl lactate, n-butyl lactate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol ethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol diethyl Ester solvents such as ether acetate, propylene glycol monomethyl ether acetate (PGMEA), isoamyl propionate, isoamyl isobutyrate, and propylene glycol diacetate; ketone solvents such as acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, diethyl ketone, di-n-butyl ketone, methyl isobutyl ketone, methyl n-amyl ketone, ethyl n-butyl ketone, methyl n-hexyl ketone, diisobutyl ketone, trimethyl nonanone, cyclobutanone, cyclopentanone, cyclohexanone, and cycloheptanone. In addition, as other solvents, one type may be used alone, or two or more types may be used in combination.

Among the solvents, at least one selected from the group consisting of alcoholic solvents and etheric solvents is preferably used as the other solvent. In addition, from the viewpoint of performing heating at the lowest possible temperature during film formation, the liquid crystal alignment agent disclosed herein is preferably substantially free of the first solvent. Specifically, the content ratio of the first solvent relative to the total amount of the solvent contained in the liquid crystal alignment agent is preferably 5% by mass or less, more preferably 1% by mass or less, further preferably 0.5% by mass or less, and particularly preferably 0% by mass.

When other solvents are used as solvents, the content ratio of other solvents relative to the total amount of solvents contained in the liquid crystal alignment agent (their total amount when two or more solvents are used) is preferably less than 90 mass%, more preferably less than 80 mass%, further preferably less than 70 mass%, further preferably less than 60 mass%, and particularly preferably less than 50 mass%.

《Other ingredients》 In addition to the polymer component and the solvent component, the liquid crystal alignment agent may also contain other components as needed.

<Compounds containing crosslinking groups> The liquid crystal alignment agent disclosed in the present invention may also contain compounds having crosslinking groups (hereinafter also referred to as "compounds containing crosslinking groups"). If a compound containing a crosslinking group is included, a liquid crystal element with better electrical properties can be obtained, which is suitable in this respect. The crosslinking group possessed by the compound containing a crosslinking group is preferably a compound having at least one selected from the group consisting of a cyclic ether group, a cyclic carbonate group, an isocyanate group, a protected isocyanate group, an oxazoline group, a β-hydroxyalkylamide group, a Meldrum's acid group, a hydroxymethyl group and an alkylhydroxymethyl group and having a molecular weight of 1000 or less. The number of crosslinking groups possessed by one molecule of the compound containing a crosslinking group is preferably two or more, and more preferably three or more. Among them, the crosslinking group-containing compound is preferably a compound having at least one selected from the group consisting of a cyclic ether group, a protected isocyanate group, a β-hydroxyalkylamide group, a hydroxymethyl group and an alkylhydroxymethyl group, and more preferably a compound having at least one selected from the group consisting of a protected isocyanate group, a β-hydroxyalkylamide group, a hydroxymethyl group and an alkylhydroxymethyl group.

Specific examples of the compound containing a crosslinking group include compounds having a cyclic ether group, such as ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trihydroxymethylpropane triglycidyl ether, N,N,N',N'-tetraglycidyl-m-xylene diamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, N,N-diglycidyl-benzylamine, N,N-diglycidyl-aminomethylcyclohexane, Hexane, N,N-diglyceryl-cyclohexylamine, etc.; compounds having a cyclic carbonate group include, for example, N,N,N',N'-tetrakis[(2-oxo-1,3-dioxacyclopentane-4-yl)ethyl]-4,4'-diaminodiphenylmethane, etc.; compounds having an isocyanate group or a protected isocyanate group include, for example, toluene diisocyanate, xylene diisocyanate, chlorophenyl diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and compounds having a protective group. Protected isocyanate compounds obtained by protecting these polyisocyanates; compounds having an oxazoline group include, for example, 2,2'-bis(4-propyl-2-oxazoline), 2,2'-bis(4-phenyl-2-oxazoline), 1,2-bis(2-oxazoline-2-yl)ethane, 1,4-bis(2-oxazoline-2-yl)cyclohexane, 1,3-bis(2-oxazoline-2-yl)benzene, 1,3-bis(4,5-dihydro-2-oxazolyl)benzene, 1,3-bis(4-methyl-2-oxazoline-2-yl)benzene, etc.; compounds having a β-hydroxyalkane Examples of the compound having an amide group include N,N,N',N'-tetrakis(2-hydroxyethyl)hexanediamide, and examples of the compound having a hydroxymethyl group or an alkylhydroxymethyl group include trihydroxymethylpropane, bis[2-ethyl-2,2-bis(hydroxymethyl)ethyl]ether, 2,2'-[oxybis(methylene)]bis[2-ethyl-1,3-propanediol], 2,2-bis(4-hydroxymethylphenyl)propane, 2,2-bis(2,3,4-trihydroxymethylphenyl)propane, and 2,4,6-tris[bis(methoxymethyl)amino]-1,3,5-triazine. As the compound having a crosslinking group, one kind may be used alone, or two or more kinds may be used in combination.

When a crosslinking group-containing compound is used, from the viewpoint of forming a stable liquid crystal alignment film and further improving the electrical properties of the obtained liquid crystal element, the content of the crosslinking group-containing compound in the liquid crystal alignment agent is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, relative to 100 parts by mass of the total amount of the polymer [P]. In addition, from the viewpoint of suppressing the performance degradation caused by excessive addition, the content of the crosslinking group-containing compound is preferably 40 parts by mass or less, and more preferably 30 parts by mass or less, relative to 100 parts by mass of the total amount of the polymer component in the liquid crystal alignment agent. In addition, as a crosslinking group-containing compound, one type can be used alone or two or more types can be used in combination.

As other components contained in the liquid crystal alignment agent, not only the above compounds can be listed, but also, for example, antioxidants, metal chelate compounds, hardening accelerators, surfactants, fillers, dispersants, photosensitizers, etc. The mixing ratio of other components can be appropriately selected according to each compound within the range that does not impair the effect of the present invention.

The solid component concentration in the liquid crystal alignment agent (the ratio of the total mass of the components of the liquid crystal alignment agent other than the solvent to the total mass of the liquid crystal alignment agent) is appropriately selected in consideration of viscosity, volatility, etc., and is preferably in the range of 1 mass % to 10 mass %. If the solid component concentration is 1 mass % or more, the film thickness of the coating can be fully ensured, and a liquid crystal alignment film showing good liquid crystal alignment can be easily obtained. On the other hand, if the solid component concentration is 10 mass % or less, the coating can be made of an appropriate thickness, and a liquid crystal alignment film showing good liquid crystal alignment can be easily obtained. In addition, the viscosity of the liquid crystal alignment agent becomes appropriate, and there is a tendency to make the coating property good.

《Liquid crystal alignment film and liquid crystal element》 The liquid crystal alignment film of the present invention is formed by a liquid crystal alignment agent prepared in the above manner. In addition, the liquid crystal element of the present invention includes a liquid crystal alignment film formed using the liquid crystal alignment agent described above. The operation mode of the liquid crystal in the liquid crystal element is not particularly limited, and can be applied to twisted nematic (TN) type, super twisted nematic (STN) type, vertical alignment (VA) type (including vertical alignment-multi-domain vertical alignment (VA-MVA) type, vertical alignment-patterned vertical alignment (VA-PVA) type, etc.), in-plane switching (IPS) type, fringe field switching (FFS) type, optically compensated bend (OCB) type, polymer stabilized alignment (PSA) type, etc. The liquid crystal element can be manufactured, for example, by a method including the following steps 1 to 3. Regarding step 1, the substrate used varies depending on the desired operation mode. Steps 2 and 3 are common to each operation mode.

<Step 1: Formation of coating film> First, a liquid crystal alignment agent is applied on a substrate, and the coated surface is preferably heated to form a coating film on the substrate. As the substrate, for example, glass such as float glass and sodium glass; transparent substrates containing plastics such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, and poly(aliphatic cycloolefin) can be used. As a transparent conductive film provided on one side of the substrate, a NESA film (registered trademark of PPG, USA) containing tin oxide (SnO ₂ ), an indium tin oxide (ITO) film containing indium oxide-tin oxide (In ₂ O ₃ -SnO ₂ ), etc. can be used. When manufacturing TN, STN or VA type liquid crystal elements, two substrates provided with patterned transparent conductive films are used. On the other hand, when manufacturing IPS or FFS type liquid crystal elements, a substrate provided with electrodes patterned into a comb shape and an opposing substrate without electrodes are used.

The method for applying the liquid crystal alignment agent to the substrate is not particularly limited, and can be carried out, for example, by spin coating, printing (for example, offset printing, flexographic printing, etc.), inkjet, slit coating, rod coater, extrusion die, direct gravure coater, chamber doctor coater, offset gravure coater, impregnation coater, MB coater, etc.

After applying the liquid crystal alignment agent, it is preferred to perform preheating (pre-baking) for the purpose of preventing the applied liquid crystal alignment agent from flowing. The pre-baking temperature is preferably 30°C to 200°C, and the pre-baking time is preferably 0.25 minutes to 10 minutes. Thereafter, the solvent is completely removed, and a calcination (post-baking) step is performed as needed for the purpose of thermally imidizing the amide structure present in the polymer. The calcination temperature (post-baking temperature) at this time is preferably 80°C to 280°C, and more preferably 80°C to 250°C. The post-baking time is preferably 5 minutes to 200 minutes. The film thickness of the formed film is preferably 0.001 μm to 1 μm.

<Step 2: Alignment treatment> In the case of manufacturing a TN type, STN type, IPS type or FFS type liquid crystal element, a treatment (alignment treatment) is performed to impart liquid crystal alignment ability to the coating formed in the step 1. Thereby, the alignment ability of the liquid crystal molecules is imparted to the coating to form a liquid crystal alignment film. As the alignment treatment, it is preferred to use a friction treatment in which the surface of the coating formed on the substrate is wiped with cotton wool or the like, or a light alignment treatment in which the coating is irradiated with light to impart liquid crystal alignment ability. On the other hand, in the case of manufacturing a vertical alignment type liquid crystal element, the coating formed in the step 1 can be directly used as a liquid crystal alignment film, or the coating can be subjected to an alignment treatment in order to further improve the liquid crystal alignment ability.

Light irradiation for photo-alignment can be performed by the following methods: a method of irradiating the coating after the post-baking step; a method of irradiating the coating after the pre-baking step and before the post-baking step; a method of irradiating the coating during the heating process of the coating in at least any one of the pre-baking step and the post-baking step, etc. As radiation irradiated to the coating, for example: ultraviolet light and visible light containing a wavelength of 150 nm to 800 nm can be used. Preferably, ultraviolet light containing a wavelength of 200 nm to 400 nm is used. When the radiation is polarized, it can be linearly polarized or partially polarized. When the radiation used is linearly polarized or partially polarized, the irradiation can be performed from a direction perpendicular to the substrate surface, from an oblique direction, or a combination of these directions. In the case of non-polarized radiation, the irradiation direction is an oblique direction.

Examples of the light source used include low-pressure mercury lamps, high-pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonance lamps, xenon lamps, and excimer lasers. The radiation dose is preferably 400 J/m ² to 50,000 J/m ² , and more preferably 1,000 J/m ² to 20,000 J/m ² . After irradiation with light for imparting alignment ability, the substrate surface may be cleaned with water, an organic solvent (e.g., methanol, isopropyl alcohol, 1-methoxy-2-propanol acetate, butyl solvent, ethyl lactate, etc.) or a mixture thereof, or the substrate may be heated.

<Step 3: Construction of liquid crystal cell> Prepare two substrates with liquid crystal alignment films formed in the above manner, and arrange liquid crystal between the two substrates arranged opposite to each other, thereby manufacturing a liquid crystal cell. When manufacturing a liquid crystal cell, for example, the following methods can be listed: arrange the two substrates opposite to each other with a gap in between so that the liquid crystal alignment films face each other, use a sealant to bond the peripheral portions of the two substrates, inject liquid crystal into the cell gap surrounded by the substrate surface and the sealant, and seal the injection hole; use a liquid crystal drop (one drop fill, ODF) method, etc. As a sealant, for example, an epoxy resin containing a hardener and aluminum oxide balls as a spacer can be used. As liquid crystal, nematic liquid crystal and disc-shaped liquid crystal can be listed, among which nematic liquid crystal is preferred.

In the PSA mode, the following process is performed: a liquid crystal and a polymerizable compound (e.g., a multifunctional (meth)acrylate compound) are filled into a cell gap together, and after the liquid crystal cell is constructed, a voltage is applied between the conductive films of a pair of substrates, and then the liquid crystal cell is irradiated with light. When a liquid crystal element of the PSA mode is manufactured, the polymerizable compound is used in an amount of 0.01 to 3 parts by mass, preferably 0.1 to 1 part by mass, relative to a total of 100 parts by mass of the liquid crystal.

When a liquid crystal element is used as a display device, a polarizing plate is then attached to the outer surface of the liquid crystal unit as needed to produce a liquid crystal element. Examples of the polarizing plate include a polarizing plate formed by sandwiching a polarizing film called "H film" between cellulose acetate protective films, or a polarizing plate including the H film itself, wherein the H film is formed by absorbing iodine while stretching and aligning polyvinyl alcohol.

The liquid crystal element of the present invention described above can be effectively applied to various purposes. Specifically, for example, it can be used as a clock, a portable game console, a word processor, a notebook personal computer, a car navigation system, a camera (camcorder), a personal digital assistant (PDA), a digital camera, a mobile phone, a smart phone, various monitors, a liquid crystal television, an information display, and other display devices or dimming devices, a phase difference film, etc.

[Examples] The following describes the implementation forms in more detail based on the examples, but the present invention is not limited to the following examples.

In the following examples, the weight average molecular weight Mw of the polymer, the imidization rate of the polyimide in the polymer solution, the solution viscosity of the polymer solution, and the epoxy equivalent are measured by the following methods. The necessary amounts of the raw material compounds and polymers used in the following examples are ensured by repeating the synthesis under the synthesis scale shown in the following synthesis examples as needed. [Weight average molecular weight Mw of polymer] The weight average molecular weight Mw is a polystyrene conversion value measured by GPC under the following conditions. Column: TSKgelGRCXLII manufactured by Tosoh Co., Ltd. Solvent: Tetrahydrofuran (polyorganosiloxane, binder resin) N,N-dimethylformamide solution containing lithium bromide and phosphoric acid (polyamide) Temperature: 40°C Pressure: 68 kgf/cm ² [Imidization rate of polyimide] The polyimide solution was poured into pure water, and the resulting precipitate was fully dried under reduced pressure at room temperature, then dissolved in deuterated dimethyl sulfoxide, and hydrogen spectroscopy nuclear magnetic resonance ( ¹ H-NMR) ^was measured at room temperature using tetramethylsilane as a reference substance. From the obtained ¹ H-NMR spectrum, the imidization rate [%] was calculated by the following formula (1). Imidization rate [%] = (1-(A ¹ /(A ² ×α))) × 100 … (1) (In formula (1), A ¹ is the peak area of protons derived from the NH group appearing around the chemical shift of 10 ppm, A ² is the peak area derived from other protons, and α is the ratio of the number of other protons to one proton of the NH group in the polymer precursor (polyamine).) [Solution viscosity of polymer solution] The solution viscosity (mPa·s) of the polymer solution was measured at 25°C using an E-type rotational viscometer. [Epoxide equivalent] The epoxy equivalent was measured by the hydrochloric acid-methyl ethyl ketone method described in Japanese Industrial Standards (JIS) C 2105.

The abbreviations of the compounds are as follows. In addition, the compounds represented by formula (X) may be simply referred to as "compound (X)" below. [Chemistry 19] [Chemistry 20] [Chemistry 21] [Chemistry 22] [Chemistry 23]

<Synthesis of polymer> 1. Synthesis of polyamine [Synthesis Example 1] 100 mol parts of 2,3,5-tricarboxycyclopentylacetic acid dianhydride (tc-1) as tetracarboxylic dianhydride, 20 mol parts of cholesteryloxy-2,4-diaminobenzene (da-13) as diamine, 40 mol parts of compound (da-2), and 40 mol parts of 4,4'-diaminobenzanilide (da-1) were dissolved in N-methyl-2-pyrrolidone (NMP) and reacted at 60°C for 6 hours to obtain a solution containing 30% by mass of polyamine. A small amount of the obtained polyamine solution was taken and NMP was added to prepare a solution with a polyamine concentration of 20 mass %, and the solution viscosity measured for this solution was 800 mPa·s. Then, the reaction solution was injected into a large excess of methanol to precipitate the reaction product. The precipitate was washed with methanol and dried at 40°C for 15 hours under reduced pressure to obtain a polymer (PAA-1). [Synthesis Example 2 to Synthesis Example 6] Except for changing the type and amount of tetracarboxylic dianhydride and diamine used as shown in Table 1 below, the same operation as Synthesis Example 1 was performed to obtain polyamines (polymers (PAA-2) to (PAA-6)).

2. Synthesis of polyimide [Synthesis Example 7] 100 mol of 2,4,6,8-tetracarboxylic acid bicyclo[3.3.0]octane-2:4,6:8-dianhydride (tc-2) as tetracarboxylic acid dianhydride, 30 mol of compound (da-14) as diamine, and 70 mol of 3,5-diaminobenzoic acid (da-16) were dissolved in NMP and reacted at 60°C for 6 hours to obtain a solution containing 30% by mass of polyimide. A small amount of the obtained polyimide solution was taken and added to NMP to prepare a solution with a polyimide concentration of 20% by mass. The solution viscosity measured for this solution was 800 mPa·s. Next, NMP was added to the obtained polyamide solution to prepare a solution with a polyamide concentration of 7% by mass, and pyridine and acetic anhydride were added to perform a dehydration and ring-closing reaction at 110°C for 4 hours. After the dehydration and ring-closing reaction, the solvent in the system was replaced with new NMP to obtain a solution containing 26% by mass of polyimide with an imidization rate of about 80% (hereinafter referred to as "polymer (PI-1)"). A small amount of the obtained polyimide solution was taken out, and NMP was added to prepare a solution with a polyimide concentration of 15% by mass. The solution viscosity measured for this solution was 120 mPa·s. Next, the reaction solution was poured into a large excess of methanol to precipitate the reaction product. The precipitate was washed with methanol and dried at 40° C. for 15 hours under reduced pressure to obtain a polymer (PI-1).

[Table 1] Polymer Name Monomer (molar parts) Imidization rate Anhydride 1 Anhydride 2 Diamine 1 Diamine 2 Diamine 3 Diamine 4 Diamine 5 Synthesis Example 1 PAA-1 tc-1 (100) - da-13 (20) da-2 (40) da-1 (40) - - - Synthesis Example 2 PAA-2 tc-1 (100) - da-15 (20) da-2 (40) da-11 (40) - - - Synthesis Example 3 PAA-3 tc-2 (80) tc-4 (20) da-14 (30) da-4 (40) da-10 (30) - - - Synthesis Example 4 PAA-4 tc-2 (80) tc-4 (20) da-7 (30) da-2 (40) da-11 (30) - - - Synthesis Example 5 PAA-5 tc-2 (80) tc-3 (20) da-14 (30) da-3 (30) da-5 (20) da-8 (15) da-12 (5) - Synthesis Example 6 PAA-6 tc-5 (50) tc-4 (50) da-4 (30) da-6 (40) da-9 (30) - - - Synthesis Example 7 PI-1 tc-2 (100) - da-14 (30) da-16 (70) - - - 80%

3. Synthesis of epoxy-containing polyorganosiloxane [Synthesis Example 8] In a reaction vessel including a stirrer, a thermometer, a dropping funnel, and a reflux cooling tube, 100.0 g of 2-(3,4-epoxyhexyl)ethyltrimethoxysilane (the compound represented by the formula (es-1)), 500 g of methyl isobutyl ketone, and 10.0 g of triethylamine were added and mixed at room temperature. Then, 100 g of deionized water was added dropwise from the dropping funnel over 30 minutes, and the mixture was reacted at 80°C for 6 hours while being stirred under reflux. After the reaction was completed, the organic layer was removed and washed with a 0.2 mass% ammonium nitrate aqueous solution until the washed water became neutral, and then the solvent and water were distilled off under reduced pressure to obtain an epoxy-containing polyorganosiloxane (referred to as "polymer (ESSQ-1)") in the form of a viscous transparent liquid. ¹ H-NMR analysis of the polymer (ESSQ-1) revealed a peak based on epoxy groups at a chemical shift (δ) of 3.2 ppm. The weight average molecular weight Mw of the obtained polymer (ESSQ-1) was 3,500, and the epoxy equivalent was 180 g/mol.

4. Synthesis of polyorganosiloxane containing specific groups [Synthesis Example 9] In a 200 mL three-necked flask, 10.0 g of a polymer (ESSQ-1), 30.28 g of methyl isobutyl ketone as a solvent, a compound (ca-1) as a modifying component (carboxylic acid having an aligning group) in an amount equivalent to 20 mol% and a compound (ca-2) in an amount equivalent to 10 mol% relative to the total amount of epoxy groups in the polymer (ESSQ-1), and 0.10 g of UCAT 18X (trade name, manufactured by San-Apro Co., Ltd.) as a catalyst were placed and reacted at 100°C with stirring for 48 hours. After the reaction, ethyl acetate was added to the reaction mixture, the resulting solution was washed with water three times, the organic layer was dried with magnesium sulfate, and the solvent was distilled off to obtain a polymer (PSQ-1). The weight average molecular weight Mw of the obtained polymer was 6,800. [Synthesis Example 10] Except that the modified components used were changed to 30 mol% of the compound (ca-1) and 10 mol% of the compound (ca-3) relative to the total amount of epoxy groups in the polymer (ESSQ-1), the same operation as in Synthesis Example 9 was performed to obtain a polymer (PSQ-2).

[Example 1] 1. Preparation of liquid crystal alignment agent Propylene carbonate (PC), diethylene glycol monomethyl ether (B1), diethylene glycol dimethyl ether (C1), and 3-methoxybutanol (MB) were added to 100 parts by mass of the polymer (PAA-1) obtained in Synthesis Example 1 and 5 parts by mass of the polymer (PSQ-1) obtained in Synthesis Example 9 to prepare a solution having a solid content concentration of 4.0% by mass and a solvent mixing ratio of PC:B1:C1:MB=15:20:30:35 (mass ratio). After the solution was fully stirred, it was filtered using a filter with a pore size of 0.2 μm to prepare a liquid crystal alignment agent (S-1).

2. Preparation of coloring composition (1) Preparation of pigment dispersion 15 parts by mass of Color Index (CI) pigment blue 15:6 as a coloring agent, 12.5 parts by mass of BYK-LPN21116 (manufactured by BYK) as a dispersant (solid content concentration 40% by mass), and 72.5 parts by mass of propylene glycol monomethyl ether acetate as a solvent were treated by a bead mill to prepare a pigment dispersion (a-1). (2) Preparation of dye solution 5 parts by mass of a coloring agent represented by the following formula (A-1) and 95 parts by mass of cyclohexanone as a solvent were mixed to prepare a dye solution (A-1). In addition, the compound represented by the following formula (A-1) is obtained by the method described in Synthesis Example 3 of Japanese Patent Laid-Open No. 2013-122577.

(3) Synthesis of adhesive resin 100 parts by mass of propylene glycol monomethyl ether acetate was placed in a flask including a cooling tube and a stirrer and replaced with nitrogen. The mixture was heated to 80°C and a mixed solution of 100 parts by mass of propylene glycol monomethyl ether acetate, 20 parts by mass of methacrylic acid, 10 parts by mass of styrene, 5 parts by mass of benzyl methacrylate, 15 parts by mass of 2-hydroxyethyl methacrylate, 23 parts by mass of 2-ethylhexyl methacrylate, 12 parts by mass of N-phenylmaleimide, 15 parts by mass of mono(2-acryloyloxyethyl) succinate and 6 parts by mass of 2,2'-azobis(2,4-dimethylvaleronitrile) was added dropwise at this temperature over a period of 1 hour. The temperature was maintained and polymerization was carried out for 2 hours. Thereafter, the temperature of the reaction solution was raised to 100°C and polymerization was further performed for 1 hour to obtain a solution containing a binder resin (B1) (solid content concentration 33% by mass, hereinafter referred to as "binder resin (B1) solution"). The Mw of the obtained binder resin was 12,200 and the Mn was 6,500.

(4) Preparation of coloring composition 46.0 parts by mass of pigment dispersion (a-1), 24.3 parts by mass of dye solution (A-1), 24.6 parts by mass of binder resin (B1) solution, 7.1 parts by mass of M-402 (a mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate) manufactured by Toagosei Co., Ltd. as a crosslinking agent, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butane-1-one (Ciba Specialty Chemicals Co., Ltd.) as a photopolymerization initiator were mixed. A coloring composition (G-1) having a solid content of 20% by weight was prepared by mixing 2.1 parts by weight of IRGACURE 369 (manufactured by DIC Corporation) as a surfactant and 0.05 parts by weight of Megafac F-554 (manufactured by DIC Corporation) as a solvent.

3. Formation of Colored Cured Film The coloring composition (G-1) was applied to a glass substrate using a rotary coater, and then pre-baked for 100 seconds using a 90°C heating plate to form a coating. During coating, the rotation speed of the rotary coater was adjusted so that the film thickness after baking would be 2.5 μm. Then, after cooling the substrate to room temperature, the coating was exposed to radiation of wavelengths of 365 nm, 405 nm, and 436 nm at an exposure dose of 400 J/m ² using a high-pressure mercury lamp to pattern the electrode portion for measurement, with the photoresist interposed therebetween. Then, a developer containing a 0.04 mass% potassium hydroxide aqueous solution at 23°C was sprayed onto the substrate under the conditions of a developing pressure of 110 kPa and a developer flow rate of 1.2 liters/minute for a time equivalent to 1.5 times the time until the film of the unexposed part disappeared and the substrate surface was visible, thereby performing spray development. After that, the substrate was washed with ultrapure water and air-dried, and then post-baked in a clean oven at 230°C for 20 minutes to form a colored cured film (film thickness 2.5 μm). An ITO film (film thickness 50 nm) was formed on the obtained colored cured film by sputtering.

4. Production of vertical liquid crystal display element On the transparent electrode surface of the glass substrate with transparent electrode including the laminated film of the colored cured film and ITO film obtained in 3. above, the liquid crystal alignment agent (S-1) prepared in 1. above was applied using a spinner, and pre-baked on a heating plate at 80°C for 1 minute. Thereafter, in an oven replaced with nitrogen, it was heated at 230°C for 1 hour to form a coating with a film thickness of 0.1 μm. Then, the same operation was repeated to produce a pair (two sheets) of substrates having a colored cured film, an ITO film, and a liquid crystal alignment film. An epoxy resin adhesive containing aluminum oxide balls with a diameter of 3.5 μm was applied to the periphery of the surface with a liquid crystal alignment film of one of the substrates by screen printing. Then, the liquid crystal alignment film surfaces of a pair of substrates were made to face each other, and the optical axes of ultraviolet rays of each substrate were pressed in a manner that the projection direction of the substrate surface was antiparallel. The adhesive was thermally cured at 150°C for 1 hour. Then, negative liquid crystal (MLC-6608 manufactured by Merck) was filled into the gap between the substrates from the liquid crystal injection port, and the liquid crystal injection port was sealed with an epoxy adhesive. Furthermore, in order to remove the flow alignment during liquid crystal injection, it was heated at 130°C and then slowly cooled to room temperature to manufacture a liquid crystal display element.

5. Evaluation of electrical properties The produced liquid crystal display element was placed in an oven at 60°C, and the VHR was measured at 1 V and 167 msec using a VHR measuring device manufactured by Toyo Technica. As the evaluation standard, "◎" was given when the VHR was 100% or less and higher than 98%, "○" was given when the VHR was 98% or less and higher than 95%, "△" was given when the VHR was 95% or less and higher than 90%, and "×" was given when the VHR was 90% or less. In addition, it can be said that the higher the VHR, the better the electrical properties caused by the solvent in the liquid crystal alignment agent penetrating into the lower layer (specifically, the colored cured film) can be suppressed. As a result, the VHR was 92.0%, and the evaluation was "△".

6. Evaluation of coating properties (printability) Liquid crystal alignment agent (S-1) was filled in an inkjet device manufactured by Shibaura, and inkjet coating was performed on a silicon wafer. Then, pre-baking was performed on a hot plate at 80°C for 1 minute. Thereafter, heating was performed at 230°C for 1 hour in an oven in which the interior of the box was replaced with nitrogen, forming a coating with a film thickness of 0.1 μm and a coating area of 100 ^cm2 (=10 cm×10 cm). For a distance of 1 mm from the center of the coating, the Alpha-Step was used to measure the uniformity of the film thickness in a direction perpendicular to the direction of travel of the inkjet head. The difference between the maximum film thickness and the minimum film thickness of the obtained film thickness profile was defined as the roughness to judge the quality of the printability. As the evaluation criteria, a roughness of 0 or more and less than 2 nm was rated as "◎", a roughness of 2 nm or more and less than 5 nm was rated as "○", a roughness of 5 nm or more and less than 10 nm was rated as "△", and a roughness of 10 nm or more was rated as "×". As a result, the roughness was 0.7 nm, and the evaluation was "◎".

[Example 3 to Example 6, Example 8, Example 10 and Comparative Example 1 to Comparative Example 4] Except that the composition of the liquid crystal alignment agent is changed as shown in Table 2 below, the liquid crystal alignment agent is prepared in the same manner as in Example 1. In addition, using the obtained liquid crystal alignment agent, a vertical liquid crystal display element is manufactured in the same manner as in Example 1, and the electrical characteristics and coating properties are evaluated. The results are shown in Table 3 below.

[Example 7] 1. Preparation of liquid crystal alignment agent Except for changing the formulation as shown in Table 2 below, a liquid crystal alignment agent (S-7) was prepared in the same manner as in Example 1. 2. Production and evaluation of a photo-vertical liquid crystal display element The composition of the liquid crystal alignment agent was changed as shown in Table 2 below. As in Example 1, the liquid crystal alignment agent was applied on the transparent electrode surface of a glass substrate with a transparent electrode including a laminated film of a colored cured film and an ITO film by using a rotator, and pre-baking and post-baking were performed to form a coating film. Next, the coated surface was irradiated with 1,000 J/m ² of polarized ultraviolet light containing a bright line of 313 nm at a direction inclined 40° relative to the substrate normal using a Hg-Xe lamp and a Glan Taylor prism to impart liquid crystal alignment capability. The same operation was repeated to produce a pair (two sheets) of substrates having a colored cured film, an ITO film, and a liquid crystal alignment film. An epoxy resin adhesive containing aluminum oxide balls with a diameter of 3.5 μm was applied to the periphery of the surface having the liquid crystal alignment film of one of the substrates by screen printing. Then, the liquid crystal alignment film surfaces of the pair of substrates were made to face each other, and the substrates were pressed together in such a way that the optical axis of the ultraviolet light of each substrate was projected in the direction of antiparallelism on the substrate surface, and the adhesive was thermally cured at 150°C for 1 hour. Next, negative liquid crystal (MLC-6608 manufactured by Merck) was filled into the gap between the substrates from the liquid crystal injection port, and then the liquid crystal injection port was sealed with an epoxy adhesive. Furthermore, in order to remove the flow alignment during the liquid crystal injection, it was heated at 130°C and then slowly cooled to room temperature to manufacture a liquid crystal display element. In addition, the electrical characteristics and coating properties of the obtained liquid crystal display element were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 3 below.

[Example 2] 1. Preparation of a liquid crystal alignment agent A liquid crystal alignment agent (S-2) was prepared in the same manner as in Example 1 except that the formulation was changed as described in Table 2 below. 2. Preparation of a liquid crystal composition A liquid crystal compound represented by the following formula (L1-1) in an amount of 5% by mass and a photopolymerizable compound represented by the following formula (L2-1) in an amount of 0.3% by mass were added to 10 g of a nematic liquid crystal (MLC-6608 manufactured by Merck) and mixed to obtain a liquid crystal composition LC1. [Chemistry 25]

3. Production of PSA-type liquid crystal display element The liquid crystal alignment agent (S-2) prepared in 1. above was applied to the transparent electrode surface of a glass substrate with a transparent electrode including a laminated film of a colored cured film and an ITO film using a rotator, and pre-baked on a hot plate at 80°C for 1 minute, and then heated at 200°C for 1 hour in an oven replaced with nitrogen to remove the solvent, thereby forming a coating film (liquid crystal alignment film) with a film thickness of 0.08 μm. This coating film was rubbed using a rubbing machine having a roller wound with rayon cloth at a roller rotation speed of 400 rpm, a stage movement speed of 3 cm/sec, and a hair pressing length of 0.1 mm. Thereafter, ultrasonic cleaning was performed in ultrapure water for 1 minute, followed by drying in a clean oven at 100°C for 10 minutes, thereby obtaining a substrate with a liquid crystal alignment film. The above operation was repeated to obtain a pair (two sheets) of substrates with a liquid crystal alignment film. In addition, the friction treatment is a weak friction treatment for the purpose of controlling the collapse of the liquid crystal and performing alignment division using a simple method. On the periphery of the surface with a liquid crystal alignment film of one of the substrates, an epoxy resin adhesive with aluminum oxide balls of 3.5 μm in diameter was applied by screen printing, and then the liquid crystal alignment film surfaces of a pair of substrates were made to face each other, overlapped and pressed, and heated at 150°C for 1 hour to thermally cure the adhesive. Next, after the liquid crystal composition LC1 is filled into the gap of the substrate from the liquid crystal injection port, the liquid crystal injection port is sealed with an epoxy adhesive, and then, in order to remove the flow alignment during the liquid crystal injection, it is heated at 150°C for 10 minutes and then slowly cooled to room temperature. Next, for the obtained liquid crystal unit, an alternating current of 10 V with a frequency of 60 Hz is applied between the electrodes, and in the state where the liquid crystal is driven, ultraviolet rays are irradiated at an irradiation dose of 50,000 J/ ^m2 using an ultraviolet irradiation device using a metal halide lamp as a light source. In addition, the irradiation dose is a value measured using a light meter that measures at a wavelength of 365 nm. A liquid crystal display element is manufactured by the method described above. 4. Evaluation The electrical characteristics and coating properties of the PSA type liquid crystal display device produced above were evaluated in the same manner as in Example 1. The results are shown in Table 3 below.

[Example 9] 1. Preparation of liquid crystal alignment agent A liquid crystal alignment agent (S-9) was prepared in the same manner as in Example 1 except that the formulation was changed as shown in Table 2 below.

2. Manufacture of rubbed FFS type liquid crystal display element The coloring composition (G-1) was applied to a glass substrate having a flat electrode (bottom electrode), an insulating layer, and a comb-shaped electrode (top electrode) laminated in sequence on one side, and to the respective surfaces of an opposing glass substrate without an electrode, by using a rotary applicator, and the same operation as "3. Formation of a colored cured film" of Example 1 was performed to form a colored cured film. Subsequently, a liquid crystal alignment agent (S-9) was applied to the side of each substrate on which the colored cured film was to be formed, using a rotator, and heated (pre-baked) on a heating plate at 80°C for 1 minute. After that, it was dried for 1 hour in a 200°C oven with nitrogen replaced inside the box (post-baking) to form a coating with an average film thickness of 0.08 μm. Then, the coating surface was rubbed using a friction machine with a roller wound with rayon cloth, with a roller rotation speed of 500 rpm, a platform movement speed of 3 cm/second, and a hair pressing length of 0.4 mm. After that, it was ultrasonically cleaned in ultrapure water for 1 minute, and then dried in a 100°C clean oven for 10 minutes to obtain a substrate with a liquid crystal alignment film. Next, for a pair of substrates with a liquid crystal alignment film, a liquid crystal injection port is left at the edge of the surface formed with the liquid crystal alignment film, and an epoxy resin adhesive with a 5.5 μm diameter aluminum oxide ball is applied by screen printing. After that, the substrates are overlapped and pressed, and the adhesive is thermally cured at 150°C for 1 hour. Next, nematic liquid crystal (MLC-6221 manufactured by Merck) is filled between the pair of substrates from the liquid crystal injection port, and the liquid crystal injection port is sealed with an epoxy adhesive. Furthermore, in order to remove the flow alignment during liquid crystal injection, it is heated at 120°C and then slowly cooled to room temperature to produce a liquid crystal unit. In addition, when a pair of substrates are overlapped, the friction method of each substrate is made anti-parallel. In addition, for the top electrode, the line width of the electrode is set to 4 μm, and the distance between the electrodes is set to 6 μm. In addition, as the top electrode, 4 systems of driving electrodes, namely electrode A, electrode B, electrode C and electrode D, are used. In this case, the bottom electrode acts as a common electrode for all 4 systems of driving electrodes, and the areas of the 4 systems of driving electrodes become pixel areas respectively. 3. Evaluation For the FFS type liquid crystal display element manufactured in the above, the electrical characteristics and coating properties are evaluated in the same way as in Example 1. Their results are shown in Table 3 below.

[Table 2] Polymer composition Additives Solvent ingredients Polymer [P] [phr] Other polymers [phr] Crosslinking agent [phr] Cyclic carbonate HO-C ₂ H ₄ -OC ₂ H ₄ -OR ₁ HO-C ₃ H ₆ -OC ₃ H ₆ -OR ₂ R ₃ -OC ₂ H ₄ -OC ₂ H ₄ -OR ₄ R ₅ -OC ₃ H ₆ -OC ₃ H ₆ -OR ₆ Other solvents R1 R2 R3 R4 R5 R6 Embodiment 1 PAA-1 (100) PSQ-1 (5) - PC (15) -CH3 (20) - -CH3 -CH3 (30) - - MB (35) Embodiment 2 PAA-2 (100) PSQ-2 (10) - 12BC (5) 23BC (5) -C2H5 (25) - -CH3 -C2H5(30) - - MB (30) BC (5) Embodiment 3 PAA-3 (100) - - PC (5) -C3H7(30) - -C2H5 -C2H5(30) - - MB (15) DAA (20) Embodiment 4 PAA-1 (100) PSQ-1 (5) - PC (15) - -CH3 (20) - - -CH3 -CH3 (30) PB (35) Embodiment 5 PAA-2 (100) PSQ-2 (10) - PC (10) - -C2H5 (25) - - -CH3 -C2H5(30) MB (35) Embodiment 6 PAA-3 (100) - - PC (5) - -C3H7(30) - - -C2H5 -C2H5(30) MB (30) BC (5) Embodiment 7 PAA-4 (100) - CR-1 (5) PC (10) -C2H5 (25) - - -CH3 -C2H5(30) MB (15) DAA (20) Embodiment 8 PAA-5 (100) - CR-2 (10) PC (10) - -C2H5 (25) -CH3 -C2H5(30) - - PB (35) Embodiment 9 PAA-6 (100) - CR-3 (20) EC (5) DO (5) -C2H5 (25) - -CH3 -C2H5(30) - - MB (30) BC (5) Embodiment 10 PAA-1 (100) - - PC (10) -C2H5 (25) - - - - - MB (35) BC (30) Comparison Example 1 - PI-1 (100) - PC (10) -C2H5 (25) - -CH3 -C2H5(30) - - MB (30) BC (5) Comparison Example 2 PAA-1 (100) - - - -C2H5 (25) - - - -CH3 -C2H5 (25) NMP (25) BC (25) Comparison Example 3 PAA-1 (100) - - PC (10) - - - - -C2H5 -C2H5 (25) NMP (25) BC (40) Comparison Example 4 PAA-1 (100) - - - - - - - - - NMP (50) BC (50)

In Table 2, the numerical values in parentheses of the polymer components and crosslinking agents represent the proportion (parts by mass) of each compound relative to 100 parts by mass of the polymers (PAA-1) to (PAA-6) and the polymer (PI-1) used in the preparation of the liquid crystal alignment agent. The numerical values in parentheses of the solvent composition represent the proportion (mass ratio) of each solvent relative to the total amount of the solvent components used in the preparation of the liquid crystal alignment agent. In addition, for dialkyl diol ether, the proportion is shown in the columns of group R ₄ and group R _6. The abbreviations of the compounds are as follows. <Solvent> MB: 3-methoxy-1-butanol BC: ethylene glycol monobutyl ether PB: propylene glycol monobutyl ether DAA: diacetone alcohol NMP: N-methyl-2-pyrrolidone

[table 3] Electrical properties of colored film stacked units Applicability evaluation VHR[%] determination Roughness [nm] determination Embodiment 1 92.0 △ 0.7 ◎ Embodiment 2 99.4 ◎ 0.5 ◎ Embodiment 3 96.6 ○ 0.9 ◎ Embodiment 4 91.5 △ 0.8 ◎ Embodiment 5 99.1 ◎ 0.9 ◎ Embodiment 6 95.6 ○ 0.5 ◎ Embodiment 7 99.2 ◎ 0.7 ◎ Embodiment 8 99.3 ◎ 0.5 ◎ Embodiment 9 99.1 ◎ 1.1 ◎ Embodiment 10 90.4 △ 4.2 ○ Comparison Example 1 82.1 × 1.8 ◎ Comparison Example 2 83.4 × 3.6 ○ Comparison Example 3 82.1 × 4.1 ○ Comparison Example 4 80.3 × 12.9 ×

As shown in Table 3, the roughness of the liquid crystal alignment film formed in Examples 1 to 10 is small and the coating (printing) is good. In addition, it can be seen that the voltage retention rate of the liquid crystal unit is higher than 90%, and a stable liquid crystal alignment film with good electrical properties can be formed. In particular, in Examples 1 to 9 in which dialkylene glycol dialkyl ether is formulated, the roughness of the liquid crystal alignment film is smaller than that of Example 10 in which dialkylene glycol dialkyl ether is not formulated, and the coating of the liquid crystal alignment agent on the substrate and the electrical properties of the liquid crystal element are well-balanced and improved. In contrast, in Comparative Example 3 using a cyclic carbonate compound as a solvent but not using a dialkylene glycol monoalkyl ether, Comparative Example 2 using a dialkylene glycol monoalkyl ether as a solvent but not using a cyclic carbonate compound, and Comparative Example 1 not using a polymer [P], the evaluation of the spreadability of the liquid crystal alignment agent was "○" or "◎", but the voltage retention rate of the liquid crystal cell was about 80%, and the electrical characteristics were poor. In addition, in Comparative Example 4 not using a cyclic carbonate compound and a dialkylene glycol monoalkyl ether as a solvent, both the spreadability and the electrical characteristics were poor results compared to Examples 1 to 10.

without

without

Claims (10)

A liquid crystal alignment agent, comprising: a polymer P having the following structural units, wherein the structural units are derived from a monomer having at least one selected from the group consisting of an amide group, a protected amide group, a urea group, and a protected urea group, and the polymer P does not contain a polymer obtained by reacting a compound represented by the following formula (CA-2), a compound represented by the following formula (CA-3), a compound represented by the following formula (CA-5), a compound represented by the following formula (DA-7), a compound represented by the following formula (DA-8), and a compound represented by the following formula (DA-9); a cyclic carbonate compound; and a dialkyl glycol monoalkyl ether,

The liquid crystal alignment agent as described in claim 1 also contains dialkylene glycol dialkyl ether. The liquid crystal alignment agent as described in claim 2, wherein the content ratio of dialkyl glycol dialkyl ether is greater than 1 mass % and less than 70 mass % relative to the total amount of the solvent contained in the liquid crystal alignment agent. The liquid crystal alignment agent as described in any one of claim 1 to claim 3, wherein the polymer P further has at least one selected from the group consisting of a group having a polymerizable carbon-carbon unsaturated bond, a photoinitiator group, and a photoalignment group. A liquid crystal alignment agent as described in any one of claim 1 to claim 3, wherein the polymer P also has at least one selected from the group consisting of a tertiary amine structure, a protected amino group, and a nitrogen-containing aromatic heterocyclic group. The liquid crystal alignment agent as described in any one of claim 1 to claim 3 also contains a compound having a cross-linking group. A liquid crystal alignment agent as described in any one of claim 1 to claim 3, wherein the content ratio of the cyclic carbonate compound relative to the total amount of the solvent contained in the liquid crystal alignment agent is greater than 0.5 mass % and less than 50 mass %. A liquid crystal alignment agent as described in any one of claim 1 to claim 3, wherein the content ratio of dialkylene glycol monoalkyl ether is greater than 1 mass % and less than 70 mass % relative to the total amount of the solvent contained in the liquid crystal alignment agent. A liquid crystal alignment film formed using a liquid crystal alignment agent as described in any one of claim 1 to claim 8. A liquid crystal element comprises the liquid crystal alignment film as described in claim 9.