JP7768017B2 - Liquid crystal alignment agent, liquid crystal alignment film and its manufacturing method, liquid crystal element, liquid crystal display device, and polymer - Google Patents

Description

The present invention relates to a liquid crystal aligning agent, a liquid crystal alignment film and its manufacturing method, a liquid crystal element, a liquid crystal display device, and a polymer.

In liquid crystal elements, liquid crystal alignment films are used to control the alignment of liquid crystal molecules in the liquid crystal layer. Liquid crystal alignment films are generally formed using a liquid crystal aligning agent containing a polymer component. Conventional methods for obtaining organic films with liquid crystal alignment control power include rubbing organic films, oblique vapor deposition of silicon oxide, and forming monomolecular films with long-chain alkyl groups, as well as irradiating photosensitive organic films with light (photoalignment method).

Photo-alignment methods have been the subject of extensive research in recent years because they can uniformly impart liquid crystal alignment to films while suppressing the generation of static electricity and dust (see, for example, Patent Documents 1 and 2). Patent Documents 1 and 2 disclose the formation of liquid crystal alignment films by photo-alignment methods using polymers with cinnamate structures.

International Publication No. 2007/071091 International Publication No. 2016/080033

Liquid crystal alignment films (photo-alignment films) obtained by photo-alignment treatment tend to have less ability to align liquid crystal molecules than those obtained by rubbing treatment. For this reason, when liquid crystal elements are driven for long periods of time, changes in retardation can occur due to prolonged backlight exposure, and the initial alignment direction of the liquid crystals can gradually shift from the initial orientation direction. Such changes in alignment can manifest as image retention (afterimages), reduced transmittance, and reduced black brightness. Liquid crystal elements are expected to offer even better display quality in order to meet the demand for ever-higher performance in recent years.

The present invention was developed in consideration of the above-mentioned problems, and its primary objective is to provide a highly reliable liquid crystal element in which the liquid crystal alignment changes little even after prolonged backlight irradiation.

The present invention provides the following means:

<1> A liquid crystal aligning agent containing a polymer (P) having a partial structure represented by the following formula (1):
(In formula (1), R ^β represents a monovalent hydrocarbon group having 1 to 10 carbon atoms, a cyano group, a nitro group, a chlorine atom, a bromine atom, an iodine atom, —SiR ² R ³ R ⁴ , —P(═O)R ² R ³ , —C≡CR ² or —NR ² R ³ ; a monovalent group R ω1 in which any methylene group in a monovalent hydrocarbon group having 2 to 10 carbon atoms has been replaced with —O—, —S— or —NR ² —; or a monovalent group in which any hydrogen atom in the group R ^ω1 or ^the monovalent hydrocarbon group having 1 to 10 carbon atoms has been replaced with a halogen atom, a cyano group, a hydroxyl group, an amino group, a thiol group or a nitro group. ^{R α} represents a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, a cyano group, a nitro group, a halogen atom, —SiR ² R ³ R ⁴ , -P(=O)R ² R ³ , -COOR ² , -C≡CR ² or -NR ² R ³ ; a monovalent group R ^ω2 in which any methylene group in a monovalent hydrocarbon group having 2 to 10 carbon atoms is replaced with -O-, -S- or -NR ² -; or a monovalent group in which any hydrogen atom in the group R ^ω2 or a monovalent hydrocarbon group having 1 to 10 carbon atoms is replaced with a halogen atom, a cyano group, a hydroxyl group, an amino group, a thiol group or a nitro group. R ² , R ³ and R ⁴ are each independently a hydrogen atom or a monovalent organic group. X ¹ is an oxygen atom or -NR ⁵ -. R ⁵ is a hydrogen atom or a monovalent organic group. R ¹ is a substituent. n is an integer of 0 to 4. m is 0 or 1. "*" represents a bond.

<2> A method for producing a liquid crystal alignment film, comprising: a step of applying the liquid crystal aligning agent according to <1> above onto a substrate to form a coating film; and a step of irradiating the coating film with light.
<3> A liquid crystal alignment film formed using the liquid crystal aligning agent according to <1> above.
<4> A liquid crystal element comprising the liquid crystal alignment film according to <3> above.

<5> A liquid crystal display device having a plurality of pixels, the liquid crystal display device comprising: a first substrate; a second substrate facing the first substrate; a liquid crystal layer provided between the first substrate and the second substrate and containing liquid crystal molecules; a first alignment film formed on the first substrate and aligning the liquid crystal molecules; and a second alignment film formed on the second substrate and aligning the liquid crystal molecules. In the liquid crystal display device, at least one of the first alignment film and the second alignment film is a photo-alignment film, and each pixel among the plurality of pixels has a first alignment region, a second alignment region, a third alignment region, and a fourth alignment region as regions in which the alignment orientations of the liquid crystal molecules are different from one another, the first alignment region, the second alignment region, the third alignment region, and the fourth alignment region are arranged side by side in the longitudinal direction of the pixel, and any two of the alignment orientation of the first alignment region, the alignment orientation of the second alignment region, the alignment orientation of the third alignment region, and the alignment orientation of the fourth alignment region are the difference in alignment orientation between the first alignment film and the second alignment film is approximately equal to an integer multiple of 90 degrees, the plurality of pixels are arranged side by side in the short-side direction of the pixel so that the alignment orientations of adjacent alignment regions in the short-side direction of the pixel are the same, and in each of the first alignment region, the second alignment region, the third alignment region, and the fourth alignment region, one of the pretilt angle defined by the first alignment film and the pretilt angle defined by the second alignment film is less than 90 degrees, and the other is substantially 90 degrees, and the photo-alignment film is formed using the liquid crystal alignment agent of <1> above.

<6> A polymer having a partial structure represented by the above formula (1).

The above configuration results in little change in liquid crystal alignment even after prolonged backlight irradiation, resulting in a highly reliable liquid crystal element.

FIG. 1 is a schematic diagram showing a schematic configuration of a liquid crystal display device. FIG. 1 is a diagram showing an example of an alignment pattern in one pixel of a liquid crystal display device. 1A and 1B are diagrams showing an example of an alignment pattern in each pixel of a liquid crystal display device, where (a) shows a first substrate and (b) shows a second substrate.

Matters related to the aspects of the present disclosure will be explained in detail below. In this specification, the term "hydrocarbon group" includes chain hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. A "chain hydrocarbon group" refers to a straight-chain hydrocarbon group or a branched hydrocarbon group that does not contain a cyclic structure and is composed solely of a chain structure. However, it may be saturated or unsaturated. An "alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic hydrocarbon structure as a ring structure and does not contain an aromatic ring structure. However, it does not have to be composed solely of an alicyclic hydrocarbon structure, and may also contain a chain structure as part of it. An "aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as a ring structure. However, it does not have to be composed solely of an aromatic ring structure, and may contain a chain structure or an alicyclic hydrocarbon structure as part of it.

The term "aliphatic hydrocarbon group" encompasses both linear hydrocarbon groups and alicyclic hydrocarbon groups. The "main chain" of a polymer refers to the longest "trunk" portion of the polymer's atomic chain. The term "side chain" of a polymer refers to the portion branching off from the "trunk" of the polymer. The term "organic group" refers to an atomic group formed by removing any hydrogen atom from a carbon-containing compound (i.e., an organic compound). The term "(meth)acrylate" encompasses both acrylate and methacrylate. The term "(meth)acrylic" encompasses both acrylic and methacrylic.

Liquid crystal alignment agent
The liquid crystal aligning agent of the present disclosure contains a polymer (P) having a partial structure represented by the following formula (1).
(In formula (1), R ^β represents a monovalent hydrocarbon group having 1 to 10 carbon atoms, a cyano group, a nitro group, a chlorine atom, a bromine atom, an iodine atom, —SiR ² R ³ R ⁴ , —P(═O)R ² R ³ , —C≡CR ² or —NR ² R ³ ; a monovalent group R ω1 in which any methylene group in a monovalent hydrocarbon group having 2 to 10 carbon atoms has been replaced with —O—, —S— or —NR ² —; or a monovalent group in which any hydrogen atom in the group R ^ω1 or ^the monovalent hydrocarbon group having 1 to 10 carbon atoms has been replaced with a halogen atom, a cyano group, a hydroxyl group, an amino group, a thiol group or a nitro group. ^{R α} represents a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, a cyano group, a nitro group, a halogen atom, —SiR ² R ³ R ⁴ , -P(=O)R ² R ³ , -COOR ² , -C≡CR ² or -NR ² R ³ ; a monovalent group R ^ω2 in which any methylene group in a monovalent hydrocarbon group having 2 to 10 carbon atoms is replaced with -O-, -S- or -NR ² -; or a monovalent group in which any hydrogen atom in the group R ^ω2 or a monovalent hydrocarbon group having 1 to 10 carbon atoms is replaced with a halogen atom, a cyano group, a hydroxyl group, an amino group, a thiol group or a nitro group. R ² , R ³ and R ⁴ are each independently a hydrogen atom or a monovalent organic group. X ¹ is an oxygen atom or -NR ⁵ -. R ⁵ is a hydrogen atom or a monovalent organic group. R ¹ is a substituent. n is an integer of 0 to 4. m is 0 or 1. "*" represents a bond.

<Polymer (P)>
The partial structure of polymer (P) represented by formula (1) has a substituent (R ^β ) at the β-position of the carbonyl carbon. In formula (1), examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by R ^β include an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an aralkyl group having 6 to 10 carbon atoms.

Alkyl groups having 1 to 10 carbon atoms may be linear or branched, and specific examples include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl groups. Cycloalkyl groups having 3 to 10 carbon atoms include cyclopentyl, cyclohexyl, and methylcyclohexyl groups. Aryl groups having 6 to 10 carbon atoms include phenyl and tolyl groups. Aralkyl groups having 6 to 10 carbon atoms include benzyl groups.

Specific examples of the group represented by R ^β which is a monovalent group (R ^ω1 ) in which any methylene group in a monovalent hydrocarbon group having 2 to 10 carbon atoms is replaced with -O-, -S- or -NR ² - include groups in which one or more methylene groups in an alkyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms or an aralkyl group having 6 to 10 carbon atoms are replaced with -O-, -S- or -NR ² -. Further specific examples of the group R ^ω1 include an alkoxy group, an alkoxyalkyl group, a group having a (poly)alkylene glycol chain, a cycloalkoxy group, an arylalkoxy group, an aralkyloxy group, etc.

When the group represented by R ^β is a monovalent group in which any hydrogen atom in a monovalent hydrocarbon group having 1 to 10 carbon atoms has been substituted with a halogen atom, examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. Specific examples of the group represented by R ^β in which a monovalent group in which a halogen atom has been substituted include a trifluoromethyl group, a perfluoroethyl group, a 2,2,2-trifluoroethyl group, a trichloromethyl group, a bromomethyl group, etc.

Specific examples of the group represented by R ^β , which is a monovalent group in which any hydrogen atom in a group R ^ω1 or a monovalent hydrocarbon group having 1 to 10 carbon atoms has been substituted with a cyano group, a hydroxyl group, an amino group, a thiol group, or a nitro group, include a cyanomethyl group, an aminomethyl group, a 2-aminoethyl group, an N-(aminomethyl)methyl group, a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a hydroxymethyloxymethyl group, a thiolmethyl group, a 2-thiolethyl group, and a nitromethyl group.

Examples of the monovalent organic groups represented by R ² , R ³ , and R ⁴ include monovalent hydrocarbon groups having 1 to 10 carbon atoms and alkoxy groups having 1 to 10 carbon atoms. Specific examples of the monovalent hydrocarbon groups having 1 to 10 carbon atoms include the same groups as those exemplified in the description of the group represented by R ^β . Examples of the alkoxy groups having 1 to 10 carbon atoms include methoxy, ethoxy, propoxy, butoxy, and pentoxy.

In terms of being resistant to deterioration even after long-term backlight irradiation and being able to obtain a highly reliable liquid crystal device, R ^β is preferably a monovalent hydrocarbon group having 1 to 10 carbon atoms, a cyano group, a nitro group, a chlorine atom, a bromine atom, an iodine atom, —SiR ² R ³ R ⁴ , —P(═O)R ² R ³ , —C≡CR ² or —NR ² R ³ , a monovalent group R ^ω1 in which any methylene group in a monovalent hydrocarbon group having 2 to 10 carbon atoms is replaced by —O—, —S— or —NR ² —, or a monovalent group in which any hydrogen atom in the group R ^ω1 or a monovalent hydrocarbon group having 1 to 10 carbon atoms is replaced by a halogen atom, a cyano group or a nitro group, an alkyl group having 1 to 6 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, a trialkylsilyl group, a cyano group, a bromine atom, an iodine atom, —NR ¹² R ¹³ (wherein R ¹² and R ¹³ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms), or a monovalent group containing -O-, -S-, or -NR ² - between the carbon-carbon bond of a monovalent hydrocarbon group having 2 to 10 carbon atoms (wherein R ² is a hydrogen atom or a monovalent organic group). Among these, R ^β is more preferably an alkyl group having 1 to 3 carbon atoms, a fluoroalkyl group having 1 to 3 carbon atoms, a trialkylsilyl group, or -NR ¹² R ¹³ , and a methyl group, an ethyl group, or a trialkylsilyl group is more preferred.

The partial structure represented by the above formula (1) has a hydrogen atom or a substituent at the α-position of the carbonyl carbon. Specific examples of R ^α in the above formula (1) when it is a monovalent hydrocarbon group having 1 to 10 carbon atoms, -SiR ² R ³ R ⁴ , -P(═O)R ² R ³ , -C≡CR ² or -NR ² R ³ , when it is a group R ^ω2 , or when it is a monovalent group in which any hydrogen atom in the group R ^ω2 or the monovalent hydrocarbon group having 1 to 10 carbon atoms is substituted with a halogen atom, a cyano group or a nitro group include the same groups as those exemplified as the group represented by R ^β . Specific examples of ^{R α} when it is a halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. Specific examples of "-COOR ² " include an alkyloxycarbonyl group, a cycloalkyloxycarbonyl group and an aryloxycarbonyl group.

The group represented by R ^α is preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a cyano group, or a monovalent group in which any methylene group in a monovalent hydrocarbon group having 2 to 10 carbon atoms is replaced with —O—, —S—, or —NR ² — (wherein R ² is a hydrogen atom or a monovalent organic group), more preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a cyano group, even more preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a cyano group, and still more preferably a hydrogen atom,

When the group represented by ^X1 is ^-NR5- , examples of the monovalent organic group represented by ^R5 include monovalent hydrocarbon groups having 1 to 10 carbon atoms and monovalent thermally eliminable groups. Specific examples of when ^R5 is a monovalent hydrocarbon group include alkyl groups having 1 to 6 carbon atoms, cycloalkyl groups having 4 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, and aralkyl groups having 6 to 10 carbon atoms. Of these, alkyl groups having 1 to 6 carbon atoms, cyclohexyl groups, and phenyl groups are preferred, and alkyl groups having 1 to 3 carbon atoms are more preferred. ^R5 may also be bonded to another group to form a ring structure together with the nitrogen atom to which ^R5 is bonded. Examples of such ring structures include a piperidine structure and a piperazine structure.

When ^R5 is a monovalent thermally detachable group, the thermally detachable group is preferably a monovalent group that is detached by heating during film formation. Specific examples of the thermally detachable group include a tert-butoxycarbonyl group (Boc group), a benzyloxycarbonyl group, a 1,1-dimethyl-2-haloethyloxycarbonyl group, an allyloxycarbonyl group, and a 2-(trimethylsilyl)ethoxycarbonyl group. Of these, the Boc group is particularly preferred because it has excellent thermal detachment properties and can reduce the amount of the detached structure remaining in the film.

In terms of being able to further enhance the photoalignment property of the partial structure represented by the above formula (1), X ¹ is preferably an oxygen atom, —NH—, —N(CH ₃ )— or —NR ¹⁵ — (R ¹⁵ is a Boc group), and more preferably an oxygen atom.

Examples of the substituent for ^R1 include an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a halogen atom, a hydroxyl group, a carboxyl group, an amino group, a cyano group, an alkylsilyl group, an alkoxysilyl group, and an ester group. n is preferably 0 to 2, more preferably 0 or 1, and even more preferably 0. When m is 1, the bond (*) in formula (1) represents a bond to another group (organic group). When m is 1, the bond (*) in formula (1) may be bonded to an atom constituting the main chain of the polymer or to an atom constituting the side chain. When m is 0, the partial structure represented by formula (1) above may be present at the terminal portion of the polymer main chain or at the terminal portion of the side chain.

The main skeleton of polymer (P) is not particularly limited. From the viewpoint of achieving good heat resistance, mechanical strength, affinity with liquid crystal, etc., polymer (P) is preferably at least one selected from the group consisting of polyamic acid, polyimide, polyamic acid ester, polyorganosiloxane, and addition polymer. Polymer (P) may have the partial structure represented by formula (1) above in its main chain, in its side chain, or in both its main chain and its side chain. Preferred examples of polymer (P) are described below.

[Polyamic acid]
The polyamic acid (hereinafter also referred to as "polyamic acid (P)") as polymer (P) can be obtained by polymerizing a monomer having the partial structure represented by formula (1) above. Methods for producing polyamic acid (P) include, for example, [1] a method of polymerizing a monomer containing a tetracarboxylic dianhydride (hereinafter also referred to as "specific acid-free dihydrate") having the partial structure represented by formula (1) above; [2] a method of polymerizing a monomer containing a diamine (hereinafter also referred to as "specific diamine") having the partial structure represented by formula (1) above; and [3] a method of polymerizing a monomer containing a specific acid-free dihydrate and a specific diamine. Among these, the use of a specific diamine is preferred because the synthesis of the monomer is relatively easy, and method [2] above is more preferred.

(Tetracarboxylic acid dianhydride)
Specific Acid Dianhydride The specific acid dianhydride is not particularly limited in structure of other parts as long as it has the partial structure represented by the above formula (1). The specific acid dianhydride preferably has the partial structure represented by the above formula (1) in its main chain. Specific examples of the specific acid dianhydride include compounds represented by each of the following formulas (5-1) to (5-4).

Other Acid Dianhydrides In the above methods [1] and [3], the tetracarboxylic acid dianhydride used in the synthesis of the polyamic acid (P) may be the specific acid dianhydride alone, or a tetracarboxylic acid dianhydride not having the partial structure represented by the above formula (1) (hereinafter also referred to as "other acid dianhydrides") may be used in combination. In the above method [2], other acid dianhydrides are used as the tetracarboxylic acid dianhydride when synthesizing the polyamic acid (P). Examples of other acid dianhydrides include aliphatic tetracarboxylic acid dianhydrides and aromatic tetracarboxylic acid dianhydrides. Examples of aliphatic tetracarboxylic acid dianhydrides include linear tetracarboxylic acid dianhydrides and alicyclic tetracarboxylic acid dianhydrides.

Specific examples of these include chain tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride;
Examples of alicyclic tetracarboxylic dianhydrides include 1,2,3,4-cyclobutane tetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutane tetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 5-(2,5-dioxotetrahydrofuran-3-yl)-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 5-(2,5-dioxotetrahydrofuran-3-yl)-8-methyl-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 2,4,6,8-tetracarboxybicyclo[3.3.0]octane-2:4,6:8-dianhydride, cyclopentane tetracarboxylic dianhydride, and cyclohexane tetracarboxylic dianhydride;
Examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, ethylene glycol bisanhydrotrimate, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, and 4,4'-carbonyldiphthalic anhydride; in addition, the tetracarboxylic dianhydrides described in JP-A-2010-97188 can also be used. One tetracarboxylic dianhydride can be used alone, or two or more tetracarboxylic dianhydrides can be used in combination.

The tetracarboxylic acid dianhydride used in the synthesis of polyamic acid preferably contains at least one selected from the group consisting of linear tetracarboxylic acid dianhydrides and alicyclic tetracarboxylic acid dianhydrides, and more preferably contains alicyclic tetracarboxylic acid dianhydrides, in order to increase the solubility of the polymer and to produce a liquid crystal alignment film with good electrical properties. The amount of alicyclic tetracarboxylic acid dianhydride used is preferably 20 mol% or more, more preferably 40 mol% or more, and even more preferably 50 mol% or more, based on the total amount of tetracarboxylic acid dianhydride used in the synthesis of polyamic acid.

(diamine)
Specific diamine The specific diamine used in the synthesis of the polyamic acid (P) is not particularly limited as long as it has the partial structure represented by the above formula (1). The specific diamine may have the partial structure represented by the above formula (1) in its main chain or in its side chain. Examples of the specific diamine include compounds represented by the following formula (6-1) and compounds represented by the following formula (6-2).
(In formula (6-1), ^A1 is a divalent group represented by formula (1) above. ^Y1 and ^Y2 are each independently a single bond or a divalent organic group.)
(In formula (6-2), ^A2 is a divalent group represented by formula (1) above. ^Y3 is a trivalent aromatic ring group. ^Y4 is a single bond or a divalent linking group. ^Y5 is a hydrogen atom or a monovalent organic group.)

In the above formula (6-1), examples of the divalent organic group represented by ^Y1 and ^Y2 include a divalent hydrocarbon group having 1 to 20 carbon atoms, a divalent group in which some of the methylene groups in the hydrocarbon group are replaced with -O-, -CO-, -COO-, or -NR ³⁰ - (R ³⁰ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms), and a divalent heterocyclic group, each of which may have a substituent. Examples of the divalent heterocyclic group include groups in which two hydrogen atoms have been removed from a nitrogen-containing heterocycle such as pyridine, piperazine, or piperidine. Examples of the substituent that ^Y1 and ^Y2 may have include a halogen atom, an alkoxy group, a hydroxyl group, a carboxyl group, a cyano group, and a nitro group.

In the above formula (6-2), the trivalent aromatic ring group represented by ^Y3 is a group obtained by removing three hydrogen atoms from the ring portion of an aromatic ring. Examples of the aromatic ring include aromatic hydrocarbon rings such as a benzene ring, a naphthalene ring, and an anthracene ring; and aromatic heterocycles such as a pyridine ring and a pyridazine ring. Of these, a benzene ring and a pyridine ring are particularly preferred. A substituent may be introduced into the aromatic ring of the aromatic ring group. Examples of the substituent include an alkyl group having 1 to 3 carbon atoms, a halogen atom, and a hydroxyl group.

Examples of the divalent linking group represented by Y ⁴ include —O—, —CO—, —COO—, —NR ³⁰ —, —CO—NR ³⁰ —, and an alkanediyl group having 1 to 3 carbon atoms.

Examples of the monovalent organic group represented by ^Y5 include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent group in which a portion of the methylene groups in the hydrocarbon group is replaced by -O-, -CO-, -COO- or ^-NR30- , and a monovalent heterocyclic group, each of which may have a substituent.

Specific examples of the specific diamine include, as the compound represented by the above formula (6-1), for example, compounds represented by each of the following formulas (6-1-1) to (6-1-22); and as the compound represented by the above formula (6-2), for example, compounds represented by each of the following formulas (6-2-1) to (6-2-4).

Other diamines In the above methods [2] and [3], the diamine used in the synthesis of the polyamic acid (P) may be the specific diamine alone, or a diamine not having the partial structure represented by the above formula (1) (hereinafter also referred to as "other diamines") may be used in combination. In the above method [1], other diamines are used as the diamine when synthesizing the polyamic acid (P). Examples of other diamines include aliphatic diamines, aromatic diamines, and diaminoorganosiloxanes. Examples of aliphatic diamines include linear diamines and alicyclic diamines.

Specific examples of diamines used in the synthesis of polyamic acid include chain diamines such as metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, and hexamethylenediamine;
Alicyclic diamines such as 1,4-diaminocyclohexane and 4,4'-methylenebis(cyclohexylamine);
Aromatic diamines include p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4-aminophenyl-4-aminobenzoate, 4,4'-diaminoazobenzene, 1,5-bis(4-aminophenoxy)pentane, 1,2-bis(4-aminophenoxy)ethane, 1,6-bis(4-aminophenoxy)hexane, bis[2-(4-aminophenyl)ethyl]hexanedioic acid, 2,6-diaminopyridine, 1,4-bis-(4-aminophenyl)-piperazine, 2,2'-dimethyl-4,4'-diaminobiphenyl, and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl. main chain diamines such as 4,4'-diaminodiphenyl ether, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-(phenylenediisopropylidene)bisaniline, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-[4,4'-propane-1,3-diylbis(piperidine-1,4-diyl)]dianiline, 4,4'-diaminobenzanilide, 4,4'-diaminostilbenzene, and 1,4-bis(4-aminophenyl)-piperazine;
Dodecanoxy-2,4-diaminobenzene, pentadecanoxy-2,4-diaminobenzene, hexadecanoxy-2,4-diaminobenzene, octadecanoxy-2,4-diaminobenzene, pentadecanoxy-2,5-diaminobenzene, octadecanoxy-2,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, 3,5-di Cholestanyl aminobenzoate, cholestenyl 3,5-diaminobenzoate, lanostannyl 3,5-diaminobenzoate, 3,6-bis(4-aminobenzoyloxy)cholestane, 3,6-bis(4-aminophenoxy)cholestane, 4-(4'-trifluoromethoxybenzoyloxy)cyclohexyl-3,5-diaminobenzoate, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-butylcyclohexane, 3,5-diaminobenzoic acid=5ξ-cholestan-3-yl, compounds represented by the following formula (E-1):
(In formula (E-1), X ^I and X ^II each independently represent a single bond, —O—, *-COO—, or *-OCO— (wherein “*” represents a bond to X ^I ). R ^I represents an alkanediyl group having 1 to 3 carbon atoms. R ^II represents a single bond or an alkanediyl group having 1 to 3 carbon atoms. R ^III represents an alkyl group, alkoxy group, fluoroalkyl group, or fluoroalkoxy group having 1 to 20 carbon atoms. a represents 0 or 1. b represents an integer of 0 to 3. c represents an integer of 0 to 2. d represents 0 or 1, provided that 1≦a+b+c≦3.)
A side chain type diamine such as a compound represented by the following formula:
Examples of diaminoorganosiloxanes include 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, and the like. In addition, diamines described in JP-A-2010-97188 can also be used.

Other diamines include diamines having a -NR- (where R is a monovalent hydrocarbon group or thermally eliminable group having 1 to 10 carbon atoms) or a nitrogen-containing heterocyclic structure (hereinafter also referred to as "nitrogen-containing diamines"). In addition to the corresponding compounds among the other diamines exemplified above, nitrogen-containing diamines also include, for example, N4,N4'-bis-(4-aminophenyl)-N4,N4'-dimethylbiphenyl-4,4'-diamine, N,N'-di(5-amino-2-pyridyl)-N,N'-di(tert-butoxycarbonyl)ethylenediamine, 6,6'-(pentamethylenedioxy)bis(3-aminopyridine), 3,5-diamino-N,N-bis(pyridin-3-ylmethyl)benzamide, and 4-(4-aminophenoxycarbonyl)-1-(4-aminophenyl)piperidine. When synthesizing polyamic acid (P), one diamine can be used alone, or two or more diamines can be used in combination.

In the polyamic acid (P), the content of the partial structure represented by the above formula (1) is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, based on the total diamine units contained in the polyamic acid (P). Furthermore, the content of the partial structure represented by the above formula (1) in the polyamic acid (P) is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less, based on the total diamine units contained in the polyamic acid (P). Having the content of the partial structure represented by the above formula (1) in the polyamic acid (P) within the above range is advantageous in that the photoreactivity of the polyamic acid (P) is good and an alignment film that exhibits good liquid crystal alignment properties even after prolonged backlight irradiation can be formed.

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

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

The synthesis reaction of polyamic acid (P) is preferably carried out in an organic solvent. The reaction temperature is preferably between -20°C and 150°C, and the reaction time is preferably between 0.1 and 24 hours. Examples of organic solvents used in the reaction include aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons. Particularly preferred organic solvents include one or more selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide, m-cresol, xylenol, and halogenated phenols, or a mixture of one or more of these solvents with other organic solvents (e.g., butyl cellosolve, diethylene glycol diethyl ether, etc.). The amount of organic solvent (a) used is preferably an amount such that the total amount (b) of tetracarboxylic dianhydride and diamine is 0.1 to 50% by mass relative to the total amount (a + b) of the reaction solution.

In this manner, a reaction solution containing dissolved polyamic acid (P) is obtained. This reaction solution may be used directly to prepare a liquid crystal aligning agent, or the polyamic acid (P) contained in the reaction solution may be isolated and then used to prepare a liquid crystal aligning agent.

(Polyamic acid ester)
The polyamic acid ester (hereinafter also referred to as "polyamic acid ester (P)") as the polymer (P) can be obtained, for example, by [I] a method of reacting the polyamic acid (P) obtained by the above synthesis reaction with an esterifying agent, [II] a method of reacting a tetracarboxylic acid diester with a diamine including a specific diamine, or [III] a method of reacting a tetracarboxylic acid diester dihalide with a diamine including a specific diamine. The polyamic acid ester (P) contained in the liquid crystal aligning agent of the present disclosure may have only an amic acid ester structure, or may be a partially esterified product in which an amic acid structure and an amic acid ester structure coexist. The reaction solution in which the polyamic acid ester (P) is dissolved may be used directly for preparing the liquid crystal aligning agent, or the polyamic acid ester (P) contained in the reaction solution may be isolated and then used for preparing the liquid crystal aligning agent.

(Polyimide)
A polyimide as the polymer (P) (hereinafter also referred to as "polyimide (P)") can be obtained, for example, by dehydrating and cyclizing the polyamic acid (P) synthesized as described above to form an imidized product. The polyimide (P) may be a fully imidized product in which all of the amic acid structures contained in its precursor polyamic acid (P) have been cyclized by dehydration, or a partially imidized product in which only a portion of the amic acid structures have been cyclized by dehydration, resulting in both amic acid structures and imide ring structures. The polyimide (P) preferably has an imidization rate of 20% or more, more preferably 30 to 95%. This imidization rate is the ratio, expressed as a percentage, of the number of imide ring structures to the total number of amic acid structures and imide ring structures in the polyimide. Here, some of the imide rings may be isoimide rings.

The dehydration ring-closing of polyamic acid (P) is preferably carried out by dissolving polyamic acid (P) in an organic solvent, adding a dehydrating agent and a dehydration ring-closing catalyst to the solution, and heating as needed. In this method, the dehydrating agent may be an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride. The amount of the dehydrating agent used is preferably 0.01 to 20 moles per mole of the amic acid structure of polyamic acid (P). The dehydration ring-closing catalyst may be a tertiary amine such as pyridine, collidine, lutidine, or triethylamine. The amount of the dehydration ring-closing catalyst used is preferably 0.01 to 10 moles per mole of the dehydrating agent used. Examples of organic solvents used in the dehydration ring-closing reaction include those listed as examples of organic solvents used in the synthesis of polyamic acid (P). The reaction temperature for the dehydration ring-closing reaction is preferably 0 to 180°C. The reaction time is preferably 1.0 to 120 hours. The reaction solution containing the polyimide (P) obtained by the above reaction may be used directly to prepare a liquid crystal aligning agent, or the polyimide (P) may be isolated and then used to prepare a liquid crystal aligning agent. The polyimide (P) can also be obtained by imidizing the polyamic acid ester (P).

The solution viscosity of the polyamic acid, polyamic acid ester, and polyimide contained in the liquid crystal alignment agent is preferably 10 to 800 mPa·s when made into a 10% by weight solution, and more preferably 15 to 500 mPa·s. The solution viscosity (mPa·s) is the value measured at 25°C using an E-type rotational viscometer for a 10% by weight polymer solution prepared using a good solvent for the polymer (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

The polystyrene-equivalent weight average molecular weight (Mw) of polyamic acid, polyamic acid ester, and polyimide measured by gel permeation chromatography (GPC) is preferably 1,000 to 500,000, and more preferably 5,000 to 100,000. The molecular weight distribution (Mw/Mn), expressed as the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) measured by GPC, is preferably 15 or less, and more preferably 10 or less.

(Polyorganosiloxane)
The polyorganosiloxane (hereinafter also referred to as "polysiloxane (P)") as the polymer (P) is not particularly limited in its production method as long as it has the partial structure represented by the above formula (1). The polysiloxane (P) can be obtained, for example, by a hydrolysis/condensation reaction of a hydrolyzable silane compound. Specific examples include the following methods [1] and [2].

[1] A method in which a hydrolyzable silane compound (ms-1) having an epoxy group, or a mixture of the silane compound (ms-1) and another silane compound, is hydrolyzed and condensed to synthesize an epoxy group-containing polyorganosiloxane, and then the resulting epoxy group-containing polyorganosiloxane is reacted with a carboxylic acid having a partial structure represented by the above formula (1) (hereinafter also referred to as "specific carboxylic acid").
[2] A method of hydrolyzing and condensing a hydrolyzable silane compound (ms-2) having a partial structure represented by the above formula (1), or a mixture of the silane compound (ms-2) and another silane compound.
Among these, the method (1) is preferable because it is simple and easy and can increase the introduction rate of the partial structure represented by the above formula (1) in the polysiloxane (P).

Specific examples of silane compounds (ms-1) include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethylmethyldimethoxysilane, 2-glycidoxyethyldimethylmethoxysilane, 2-glycidoxyethyldimethylethoxysilane, 4-glycidoxypropyltrimethoxysilane, 4-glycidoxypropyltriethoxy ... Examples of suitable silane compounds include 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-(3,4-epoxycyclohexyl)propyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, and 3-(3,4-epoxycyclohexyl)propyltrimethoxysilane. These compounds can be used alone or in combination as the silane compound (ms-1).

The other silane compounds used in the synthesis of the epoxy group-containing polyorganosiloxane are not particularly limited as long as they are hydrolyzable silane compounds.Specific examples thereof include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane, and dimethyldiethoxysilane;
Nitrogen- and sulfur-containing alkoxysilanes such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, mercaptomethyltrimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(3-cyclohexylamino)propyltrimethoxysilane, and N-2-(aminoethyl)-3-aminopropyltrimethoxysilane;
Examples of the other silane compounds include unsaturated hydrocarbon-containing alkoxysilanes such as 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, 6-(meth)acryloyloxyhexyltrimethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and p-styryltrimethoxysilane; as well as trimethoxysilylpropylsuccinic anhydride. These other silane compounds may be used alone or in combination of two or more. In this specification, "(meth)acryloxy" encompasses both "acryloxy" and "methacryloxy."

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

The above hydrolysis and condensation reaction is preferably carried out by heating, for example, in an oil bath. In this case, the heating temperature is preferably 130°C or less, and the heating time is preferably 0.5 to 12 hours. After the reaction is complete, the organic solvent layer separated from the reaction solution is dried with a desiccant, if necessary, and the solvent is then removed to obtain the desired polysiloxane. Note that the method for synthesizing polysiloxane is not limited to the above hydrolysis and condensation reaction; for example, it may also be performed by reacting a hydrolyzable silane compound in the presence of oxalic acid and alcohol.

In the method [1] above, the epoxy group-containing polyorganosiloxane obtained by the above reaction is then reacted with a specific carboxylic acid. This causes the epoxy groups of the epoxy group-containing polyorganosiloxane to react with the carboxyl groups of the specific carboxylic acid, resulting in the production of polyorganosiloxane (P) having the partial structure represented by formula (1) above in its side chain.

Specific examples of the specific carboxylic acid include compounds represented by the following formulas (7-1) to (7-5).

The content of the partial structure represented by the above formula (1) in one molecule of polysiloxane (P) is preferably 5 mol % or more, more preferably 10 mol % or more, and even more preferably 15 mol % or more, relative to the silicon atoms in polysiloxane (P). Furthermore, the content of the partial structure represented by the above formula (1) in one molecule of polysiloxane (P) is preferably 70 mol % or less, more preferably 60 mol % or less, and even more preferably 50 mol % or less, relative to the silicon atoms in polysiloxane (P). Having the content of the partial structure represented by the above formula (1) in polysiloxane (P) within the above range is preferable in that it improves the photoreactivity of polysiloxane (P) and enables the formation of an alignment film that exhibits good liquid crystal alignment properties even after long-term backlight irradiation.

When synthesizing polysiloxane (P), the carboxylic acid used in the reaction with the epoxy group-containing polyorganosiloxane may be the specific carboxylic acid alone, but carboxylic acids other than the specific carboxylic acid may also be used in combination. The other carboxylic acid may be any carboxylic acid that does not have the partial structure represented by formula (1) above, and various carboxylic acids can be used. Examples of other carboxylic acids include carboxylic acids with a mesogenic structure.

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

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

When the polysiloxane (P) is prepared into a 10% by mass solution, it preferably has a solution viscosity of 1 to 500 mPa·s, and more preferably 3 to 200 mPa·s. The polystyrene-equivalent weight average molecular weight (Mw) of the polysiloxane (P), measured by GPC, is preferably 1,000 to 200,000, more preferably 2,000 to 50,000, and even more preferably 3,000 to 20,000.

(addition polymer)
The method for producing the addition polymer as polymer (P) (hereinafter also referred to as "addition polymer (P)") is not particularly limited, as long as it has the partial structure represented by formula (1) above. The addition polymer (P) is a polymer having a structural unit derived from a monomer having a polymerizable carbon-carbon unsaturated bond. The addition polymer (P) can be obtained, for example, by polymerizing an unsaturated monomer (ma-1) having the partial structure represented by formula (1) above, or a mixture of the unsaturated monomer (ma-1) and another unsaturated monomer.

As the unsaturated monomer, any monomer having a polymerizable carbon-carbon unsaturated bond can be used. Examples of such monomers include compounds having a (meth)acryloyl group, a vinyl group, a vinylphenyl group, a maleimide group, etc. As the unsaturated polymer (P), at least one selected from the group consisting of poly(meth)acrylate, a maleimide polymer, and a styrene-maleimide copolymer can be preferably used, since this allows the formation of a liquid crystal alignment film with excellent liquid crystal alignment properties.

The unsaturated monomer (ma-1) is not particularly limited as long as it has the partial structure represented by the above formula (1). Specific examples of the unsaturated monomer (ma-1) include compounds represented by each of the following formulas (8-1) to (8-10).
(In formulas (8-1) to (8-4), R represents a hydrogen atom or a methyl group.)

Specific examples of other unsaturated monomers include (meth)acrylic compounds such as unsaturated carboxylic acids, such as (meth)acrylic acid, α-ethylacrylic acid, maleic acid, fumaric acid, and vinylbenzoic acid; unsaturated carboxylic acid esters, such as alkyl (meth)acrylates (for example, methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc.), cycloalkyl (meth)acrylates, benzyl (meth)acrylate, trimethoxysilylpropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxybutyl (meth)acrylate, and 4-hydroxybutyl glycidyl ether (meth)acrylate; and unsaturated polycarboxylic acid anhydrides, such as maleic anhydride;
Aromatic vinyl compounds such as styrene, methylstyrene, divinylbenzene, and 4-(glycidyloxymethyl)styrene; conjugated diene compounds such as 1,3-butadiene and 2-methyl-1,3-butadiene;
Examples of the unsaturated monomer include maleimide compounds such as N-methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, 4-(2,5-dioxo-3-pyrrolin-1-yl)benzoic acid, N-(4-glycidyloxyphenyl)maleimide, N-glycidylmaleimide, 3-maleimidobenzoic acid, 3-maleimidopropionic acid, 3-(2,5-dioxo-3-pyrrolin-1-yl)benzoic acid, and methyl 4-(2,5-dioxo-3-pyrrolin-1-yl)benzoate. In synthesizing the addition polymer (P), one type of other unsaturated monomer may be used alone, or two or more types may be used in combination.

The content of the partial structure represented by formula (1) in one molecule of addition polymer (P) is preferably 1 mol % or more, more preferably 2 mol % or more, and even more preferably 5 mol % or more, based on all structural units in addition polymer (P). Furthermore, the content of the partial structure represented by formula (1) in one molecule of addition polymer (P) is preferably 60 mol % or less, more preferably 50 mol % or less, and even more preferably 40 mol % or less, based on all structural units in addition polymer (P). Having the content of the partial structure represented by formula (1) in addition polymer (P) within the above range is preferable in that it improves the photoreactivity of addition polymer (P) and enables the formation of an alignment film that exhibits good liquid crystal alignment properties even after prolonged backlight irradiation.

The addition polymer (P) can be obtained, for example, by polymerizing the monomers in the presence of a polymerization initiator. Preferred polymerization initiators are azo compounds such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile). The polymerization initiator is preferably used in an amount of 0.01 to 30 parts by mass per 100 parts by mass of all monomers used in the reaction.

The above polymerization reaction is preferably carried out in an organic solvent. Examples of organic solvents used in the reaction include alcohols, ethers, ketones, amides, esters, and hydrocarbon compounds, with diethylene glycol ethyl methyl ether and propylene glycol monomethyl ether acetate being preferred. The reaction temperature is preferably 30°C to 120°C, and the reaction time is preferably 1 to 36 hours. The amount of organic solvent (a) used is preferably such that the total amount of monomers (b) used in the reaction is 0.1 to 60% by mass relative to the total amount of the reaction solution (a + b).

The weight average molecular weight (Mw) of the addition polymer (P) measured by GPC in terms of polystyrene is preferably 250 to 500,000, and more preferably 500 to 100,000.

The method for producing the addition polymer (P) is not limited to the above. For example, the addition polymer (P) can also be obtained by polymerizing a monomer containing an unsaturated monomer (m-1) having an epoxy group in the presence of a polymerization initiator, and then reacting the resulting polymer with a specific carboxylic acid.

When polymer (P) has the partial structure represented by formula (1) above in its main chain, from the viewpoint of ease of introduction of the partial structure represented by formula (1) above, polymer (P) is preferably at least one selected from the group consisting of polyamic acid, polyimide, and polyamic acid ester. When polymer (P) has the partial structure represented by formula (1) above in its side chain, polymer (P) is preferably at least one selected from the group consisting of polyamic acid, polyimide, polyamic acid ester, polyorganosiloxane, and addition polymer.

<Other ingredients>
The liquid crystal aligning agent of the present disclosure may further contain a component (hereinafter also referred to as "other component") different from the polymer (P). Examples of the other component include a polymer not having the partial structure represented by the above formula (1) (hereinafter also referred to as "polymer (Q)"), a crosslinking agent, a solvent, etc.

(Polymer (Q))
The polymer (Q) can be used for the purpose of improving the solubility of the polymer component, the alignment property and electrical properties of the liquid crystal alignment film, etc. Examples of the polymer (Q) include polymers having a main skeleton such as polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane, polyester, polyamide, polybenzoxazole precursor, polybenzoxazole, cellulose derivative, polyacetal, and addition polymer. When preparing the liquid crystal alignment agent, one type of polymer (Q) may be used alone, or two or more types may be used in combination.

Polymer (Q) is preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, and addition polymer, as this can improve the liquid crystal alignment and electrical properties of the resulting liquid crystal element. Specific examples of polyamic acid, polyamic acid ester, and polyimide as polymer (Q) include polymers obtained by reacting the other acid dianhydrides described above with other diamines. The addition polymer as polymer (Q) is preferably a polymer obtained using one or more monomers having a (meth)acryloyl group, vinyl group, vinylphenyl group, or maleimide group, and is preferably at least one selected from the group consisting of poly(meth)acrylate, maleimide-based polymer, and styrene-maleimide-based copolymer.

When polymer (Q) is contained in the liquid crystal aligning agent, the content of polymer (Q) in the liquid crystal aligning agent is preferably 20 to 99.9 parts by mass, and more preferably 30 to 99 parts by mass, per 100 parts by mass of the total amount of polymer (P) and polymer (Q).

Furthermore, when polymer (Q) is contained in the liquid crystal aligning agent, the content of polymer (P) in the liquid crystal aligning agent is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, per 100 parts by mass of polymer (Q). Furthermore, the content of polymer (P) is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and even more preferably 100 parts by mass or less, per 100 parts by mass of polymer (Q).

(Crosslinking agent)
The liquid crystal aligning agent of the present disclosure may contain a crosslinking agent. By blending a crosslinking agent in the liquid crystal aligning agent, it is possible to enhance the effect of improving reliability against long-term irradiation of a backlight, which is preferable.

The crosslinking agent is preferably a compound having a functional group capable of reacting with a functional group (e.g., an amino group, a carboxyl group, an epoxy group, a polymeric unsaturated bond group, etc.) present in the polymer (P). Specifically, it is preferably a compound having a molecular weight of 1,000 or less and having at least one group selected from the group consisting of a cyclic ether group, a carboxyl group, a cyclic carbonate group, an alcoholic hydroxyl group, an amino group, a protected amino group, a protected isocyanate group, a trialkoxysilyl group, and a polymerizable unsaturated bond group. The number of crosslinkable groups present in the crosslinking agent is preferably two or more, more preferably three or more, and even more preferably three to eight.

When a crosslinking agent is added, the content of the crosslinking agent in the liquid crystal aligning agent is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, per 100 parts by mass of the total amount of polymer components in the liquid crystal aligning agent. Furthermore, from the viewpoint of suppressing performance degradation caused by the addition of an excessive amount, the content of the crosslinking agent is preferably 40 parts by mass or less, and more preferably 30 parts by mass or less, per 100 parts by mass of the total amount of polymer components in the liquid crystal aligning agent. Note that one type of crosslinking agent can be used alone, or two or more types can be used in combination.

(solvent)
The liquid crystal aligning agent of the present disclosure is preferably prepared as a liquid composition in which the polymer (P) and components used as needed are dispersed or dissolved in an appropriate solvent. The solvent used is preferably an organic solvent, such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,2-dimethyl-2-imidazolidinone, γ-butyrolactone, γ-butyrolactam, N,N-dimethylformamide, N,N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone (diacetone alcohol), ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, or ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisopentyl ether, ethylene carbonate, propylene carbonate, etc. These may be used alone or in combination of two or more.

Other components include, in addition to solvents, antioxidants, metal chelate compounds, curing accelerators, surfactants, fillers, dispersants, photosensitizers, etc. The blending ratios of these can be selected appropriately for each compound, as long as they do not impair the effects of the present disclosure.

The solids concentration in the liquid crystal aligning agent (the proportion of the total mass of the liquid crystal aligning agent's components other than the solvent to the total mass of the liquid crystal aligning agent) is selected appropriately taking into consideration viscosity, volatility, etc., but is preferably in the range of 1 to 10% by mass. That is, the liquid crystal aligning agent is applied to the substrate surface as described below, and preferably heated to form a coating film that is a liquid crystal alignment film or a coating film that will become a liquid crystal alignment film. In this case, a solids concentration of 1% by mass or more is preferable because it ensures a sufficient coating film thickness and makes it easier to obtain a good liquid crystal alignment film. Furthermore, a solids concentration of 10% by mass or less ensures that the coating film does not become too thick, allowing a good liquid crystal alignment film to be obtained, and also ensures appropriate viscosity of the liquid crystal aligning agent, improving coatability.

From the viewpoint of fully obtaining the effects of the present disclosure, the content of the polymer component in the liquid crystal aligning agent is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 50% by mass or more, relative to 100 parts by mass of the total solid components (i.e., components other than the solvent) in the liquid crystal aligning agent.

<Liquid crystal alignment film and liquid crystal element>
The liquid crystal alignment film of the present disclosure is formed using the liquid crystal alignment agent prepared as described above. Furthermore, the liquid crystal element of the present disclosure 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 various modes can be applied, such as TN (Twisted Nematic) type, STN (Super Twisted Nematic) type, VA (Vertical Alignment) type (including VA-MVA type, VA-PVA type, etc.), IPS (In-Plane Switching) type, FFS (Fringe Field Switching) type, and OCB (Optically Compensated Bend) type. The liquid crystal element can be manufactured, for example, by a method including the following steps 1 to 3. In step 1, the substrate used varies depending on the desired operation mode. Steps 2 and 3 are common to all operation modes.

(Step 1: Formation of coating film)
First, a liquid crystal alignment agent is applied to a substrate, and the coated surface is preferably heated to form a coating film on the substrate. Examples of substrates that can be used include glass, such as float glass or soda glass; and transparent substrates made of plastics, such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, and poly(alicyclic olefin). Examples of transparent conductive films that can be provided on one side of the substrate include a NESA film (registered trademark of PPG, USA) made of tin oxide (SnO ₂ ) and an ITO film made of indium oxide-tin oxide (In ₂ O ₃ -SnO ₂ ). When manufacturing TN-, STN-, or VA-type liquid crystal devices, two substrates with patterned transparent conductive films are used. On the other hand, when manufacturing IPS- or FFS-type liquid crystal devices, one substrate is provided with an electrode made of a comb-shaped patterned transparent conductive film or metal film, and another substrate with no electrode is used. Examples of metal films that can be used include a film made of a metal, such as chromium. The liquid crystal alignment agent is applied to the substrate on the electrode-forming surface, preferably by offset printing, spin coating, roll coating, or inkjet printing.

After applying the liquid crystal alignment agent, preheating (prebaking) is preferably performed to prevent dripping of the applied liquid crystal alignment agent. The prebaking temperature is preferably 30 to 150°C, and more preferably 40 to 120°C. The prebaking time is preferably 0.25 to 10 minutes.

Thereafter, the solvent is further removed, and if necessary, a baking (post-baking) step is carried out to thermally imidize the amic acid structure present in the polymer. The baking temperature (post-baking temperature) at this time is preferably 250°C or lower, more preferably 230°C or lower, and even more preferably 180°C or lower, from the viewpoints of suppressing degradation such as discoloration due to high temperatures when forming a liquid crystal alignment film on a color filter and reducing environmental impact. Furthermore, from the viewpoint of suppressing deterioration of liquid crystal alignment properties and reliability due to the influence of solvent components remaining in the film, the post-baking temperature is preferably 80°C or higher, more preferably 120°C or higher. The post-baking time is preferably 5 to 150 minutes. The film thickness of the film formed in this manner is preferably 0.001 to 1 μm. After applying the liquid crystal alignment agent to a substrate, the organic solvent is removed to form a liquid crystal alignment film, or a coating film that will become a liquid crystal alignment film.

(Step 2: Alignment Treatment)
When producing a TN-type, STN-type, IPS-type, or FFS-type liquid crystal element, the coating film formed in step 1 above is subjected to a treatment (alignment treatment) to impart liquid crystal alignment ability. This imparts the alignment ability of liquid crystal molecules to the coating film, turning it into a liquid crystal alignment film. As the alignment treatment, a rubbing treatment in which the surface of the coating film formed on the substrate is rubbed with cotton or the like, or a photo-alignment treatment in which the coating film is irradiated with light to impart liquid crystal alignment ability, is preferably used. When producing a vertical alignment type liquid crystal element, the coating film formed in step 1 above may be used as a liquid crystal alignment film as is, or the coating film may be subjected to an alignment treatment to further enhance the liquid crystal alignment ability.

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

Examples of light sources that can be used include low-pressure mercury lamps, high-pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonance lamps, xenon lamps, and excimer lasers. The radiation dose is preferably 400 to 20,000 J/ ^m² , and more preferably 1,000 to 5,000 J/ ^m² . The coating film may be irradiated with light while being heated to enhance its reactivity. The method may further include a step of contacting the organic film that has been subjected to the light irradiation treatment with water, a water-soluble organic solvent, or a mixed solvent of water and a water-soluble organic solvent.

(Step 3: Construction of liquid crystal cell)
Two substrates each having a liquid crystal alignment film formed thereon are prepared as described above, and a liquid crystal cell is fabricated by disposing a liquid crystal between the two substrates. Examples of methods for fabricating a liquid crystal cell include: (1) arranging the two substrates facing each other with a gap (spacer) between them so that the liquid crystal alignment films face each other, bonding the peripheries of the two substrates together using a sealant, injecting liquid crystal into the substrate surfaces and the cell gap defined by the sealant, and then sealing the injection hole; and (2) applying a sealant to a predetermined location on one of the substrates having a liquid crystal alignment film, dropping liquid crystal onto several predetermined locations on the liquid crystal alignment film, and then bonding the other substrate so that the liquid crystal alignment film faces each other, and spreading the liquid crystal over the entire surface of the substrate (ODF method). The fabricated liquid crystal cell is preferably further heated to a temperature at which the liquid crystal used assumes an isotropic phase, followed by slow cooling to room temperature to remove flow alignment that occurs during liquid crystal filling.

The sealing agent can be, for example, an epoxy resin containing a curing agent and aluminum oxide spheres as spacers. The spacers can be photospacers, bead spacers, etc.

Liquid crystals used include nematic liquid crystals and smectic liquid crystals, with nematic liquid crystals being preferred. Examples of nematic liquid crystals that can be used include Schiff-base liquid crystals, azoxy liquid crystals, biphenyl liquid crystals, phenylcyclohexane liquid crystals, ester liquid crystals, terphenyl liquid crystals, biphenylcyclohexane liquid crystals, pyrimidine liquid crystals, dioxane liquid crystals, bicyclooctane liquid crystals, and cubane liquid crystals. These liquid crystals may also be used with the addition of, for example, cholesteric liquid crystals, chiral agents, or ferroelectric liquid crystals.

Next, if necessary, a polarizing plate is attached to the outer surface of the liquid crystal cell. Examples of polarizing plates include a polarizing film called an "H film" made by stretching and aligning polyvinyl alcohol and absorbing iodine, sandwiched between cellulose acetate protective films, or a polarizing plate made of the H film itself. This completes the liquid crystal device.

The liquid crystal element of the present disclosure can be effectively applied to a variety of applications. Specifically, it can be used in various display devices such as watches, portable game consoles, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, LCD televisions, and information displays, as well as light control films. Furthermore, liquid crystal elements formed using the liquid crystal alignment agent of the present disclosure can also be used in optical films such as retardation films.

《Liquid crystal display device》
One embodiment of the liquid crystal display device of the present invention has a photo-alignment film formed using the liquid crystal aligning agent described above as a liquid crystal alignment film. The liquid crystal display device of the present invention will be described below with reference to the accompanying drawings as appropriate.

As shown in FIG. 1, the liquid crystal display device 10 comprises a pair of substrates consisting of a first substrate 11 and a second substrate 12, and a liquid crystal layer 13 disposed between the first substrate 11 and the second substrate 12. The liquid crystal display device 10 is a thin film transistor (TFT) type liquid crystal display device. However, the present invention may also be applied to other driving methods (e.g., passive matrix method, plasma address method, etc.).

The first substrate 11 is a TFT substrate in which pixel electrodes 15 made of a transparent conductor such as ITO (Indium Tin Oxide), TFTs serving as switching elements, and various wiring such as scanning lines and signal lines are arranged on the surface of a transparent substrate 14 made of glass, resin, or the like facing the liquid crystal layer 13. The second substrate 12 is a CF substrate in which a black matrix 17, color filters 18, and an opposing electrode 19 (also called a common electrode) made of a transparent conductor are arranged on the surface of a transparent substrate 16 made of glass, resin, or the like facing the liquid crystal layer 13.

A liquid crystal alignment film is formed on the pair of substrates 11, 12, which aligns liquid crystal molecules in a predetermined direction relative to the film surface. The liquid crystal alignment film is a vertical alignment film. The liquid crystal display device 10 has, as liquid crystal alignment films, a first alignment film 22 formed on the electrode arrangement surface of the first substrate 11 and a second alignment film 23 formed on the electrode arrangement surface of the second substrate 12.

The first substrate 11 and the second substrate 12 are arranged with a predetermined gap (cell gap) between them via spacers 24, so that the electrode arrangement surface of the first substrate 11 faces the electrode arrangement surface of the second substrate 12. While columnar spacers are shown as the spacers 24 in FIG. 1, other spacers such as bead spacers may also be used. The pair of opposing substrates 11, 12 are bonded together at their peripheries via a sealant 25. A liquid crystal composition is filled in the space surrounded by the first substrate 11, the second substrate 12, and the sealant 25. This forms a liquid crystal layer 13 between the first substrate 11 and the second substrate 12. The liquid crystal layer 13 is filled with liquid crystal having negative dielectric anisotropy.

Polarizing plates (not shown) are arranged on the outside of each of the first substrate 11 and second substrate 12. A terminal area is provided on the outer edge of the first substrate 11. Driver ICs and other components for driving the liquid crystal are connected to this terminal area to drive the liquid crystal display device 10.

At least one of the first alignment film 22 and the second alignment film 23 is a photo-alignment film, and in this embodiment, at least the first alignment film 22 is a photo-alignment film. In this specification, the term "photo-alignment film" refers to a liquid crystal alignment film that has been imparted with liquid crystal alignment ability by irradiating a coating film formed using a polymer having photo-alignment groups with polarized or unpolarized light. A "photo-alignment group" is a functional group that imparts anisotropy to a film through a photoisomerization reaction, photodimerization reaction, photodecomposition reaction, photorearrangement reaction, or the like caused by light irradiation.

The first alignment film 22 is subjected to a photo-alignment process, which involves split exposure so that the alignment orientation of the liquid crystal molecules varies from region to region. The first alignment film 22 is formed by irradiating a coating film formed using a liquid crystal alignment agent containing a polymer (P) having a partial structure represented by formula (1) above with polarized radiation at an angle multiple times using a photomask (e.g., a polarizer). On the other hand, the second alignment film 23 is not split-exposed. In this embodiment, the second alignment film 23 is a coating film formed using the same liquid crystal alignment agent as the first alignment film 22, and is used as is without being irradiated with light. This results in a difference between the pretilt angle determined by the first alignment film 22 and the pretilt angle determined by the second alignment film 23. Specifically, the pretilt angle determined by the first alignment film 22 is less than 90 degrees, and the pretilt angle determined by the second alignment film 23 is substantially 90 degrees.

In addition, when forming the second alignment film 23, instead of irradiating the organic film formed from the liquid crystal alignment agent with light to make the pretilt angle defined by the second alignment film 23 substantially 90 degrees, the entire surface of the organic film formed from the liquid crystal alignment agent may be exposed to unpolarized light from the substrate normal direction without using a photomask, thereby making the pretilt angle defined by the second alignment film 23 substantially 90 degrees. In this case, the exposure light for the second substrate 12 may be either parallel or diffused light. The "pretilt angle" is the angle between the surface of the alignment film and the long axis direction of the liquid crystal molecules near the alignment film when the voltage is off.

The liquid crystal display device 10 has a plurality of pixels 30, which are arranged in a matrix in the display area of the liquid crystal display device 10. Each pixel area of the pixels 30 is divided into alignments, and has multiple areas in which the alignment direction of the liquid crystal molecules differs from one another. This compensates for the viewing angle characteristics of the liquid crystal display device 10.

In this specification, the term "pixel" refers to the smallest unit that expresses the shade (gradation) of each color in a display, and corresponds to the unit that expresses each gradation of R, G, B, etc. in a color filter display device, for example. Therefore, when referring to a "pixel," it refers to each R pixel, G pixel, and B pixel individually, rather than a color display pixel (picture element) that combines R pixels, G pixels, and B pixels. In other words, in the case of a color LCD display device, one pixel corresponds to one of the colors of the color filter.

Figure 2 shows an example of the orientation pattern of pixel 30. In Figure 2(a), the cone represents a liquid crystal molecule 35, with the apex side of the cone facing the first substrate 11 and the bottom side of the cone facing the second substrate 12. Figure 2(a) is a view of the liquid crystal display device 10 from the second substrate 12 side.

2(a), each pixel 30 has four alignment regions in which the alignment orientations of the liquid crystal molecules 35 differ from one another. These four alignment regions (first domain 31, second domain 32, third domain 33, and fourth domain 34) are arranged side by side in the longitudinal direction of the pixel 30 (the Y direction in FIG. 2) within one pixel. The alignment orientations of the liquid crystal molecules 35 in the first to fourth domains 31 to 34 are such that the difference between any two alignment orientations is approximately equal to an integer multiple of 90 degrees. In this specification, unless otherwise specified, the "alignment orientation of liquid crystal molecules" refers to the alignment orientation of liquid crystal molecules near the center in the plane and thickness direction of the liquid crystal layer 13 when a voltage is applied to the liquid crystal display device 10.

Specifically, when the short-side direction of the pixel 30 (the X direction in Figure 2) is set to 0 degrees, the orientation direction of the liquid crystal molecules 35 is substantially 45 degrees in the first domain 31, substantially 135 degrees in the second domain 32, substantially 225 degrees in the third domain 33, and substantially 315 degrees in the fourth domain 34. As shown in Figure 2(a), these four domains 31 to 34 are arranged within one pixel along the longitudinal direction of the pixel 30 in the following order: fourth domain 34, second domain 32, third domain 33, first domain 31. A signal line 36 is arranged at a position that divides the light-transmitting region of each pixel 30 (hereinafter also referred to as the "pixel region") into two in the longitudinal direction of the pixel 30. The two domains that form one side of the pixel region divided by the signal line 36 (the fourth domain 34 and the second domain 32) and the two domains that form the other side (the third domain 33 and the first domain 31) have liquid crystal molecules 35 aligned in directions that differ by 180 degrees from each other (see Figure 2(a)).

In this specification, the terms "substantially 45 degrees," "substantially 135 degrees," "substantially 225 degrees," and "substantially 315 degrees" refer to the ranges of 45 degrees ±0.5 degrees, 135 degrees ±0.5 degrees, 225 degrees ±0.5 degrees, and 315 degrees ±0.5 degrees, respectively. Each angle is preferably β degrees ±0.2 degrees, and more preferably β degrees ±0.1 degrees (where β is 45, 135, 225, or 315).

2(b) and 2(c) are schematic diagrams showing the orientation (tilt orientation) of the long axis direction of the liquid crystal molecules on the alignment film surface of each substrate of one pixel 30 projected onto the substrate in the voltage-off state. In FIG. 2, (b) shows the first substrate 11, and (c) shows the second substrate 12. The arrow 37 in FIG. 2 indicates the tilt orientation. In the liquid crystal display device 10, the first alignment film 22 of the first and second alignment films 22 and 23 is irradiated with polarized radiation in a direction corresponding to the alignment orientation of the liquid crystal molecules 35, thereby imparting the desired pretilt angle characteristics to each of the domains 31 to 34. On the other hand, the second alignment film 23 is not irradiated with polarized ultraviolet light. Through this exposure process, in the alignment regions of each of the first to fourth domains 31 to 34, the pretilt angle θ1 defined by the first alignment film 22 is less than 90 degrees, and the pretilt angle θ2 defined by the second alignment film 23 is substantially 90 degrees.

The pretilt angle θ1 should be smaller than the pretilt angle θ2 defined by the second alignment film 23. From the viewpoint of suppressing response delay of the liquid crystal molecules 35, the pretilt angle θ1 is preferably 89.0 degrees or less, and more preferably 88.5 degrees or less. Furthermore, from the viewpoint of suppressing a decrease in the contrast of the liquid crystal display device 10, the pretilt angle θ1 is preferably 81.0 degrees or more, and more preferably 83.0 degrees or more. In this specification, "substantially 90 degrees" refers to a range of 90 degrees ±0.5 degrees.

As shown in FIG. 2(b), the tilt orientation on the first substrate 11 side is different in each of the first to fourth domains 31 to 34, and the difference in tilt orientation between any two domains is approximately equal to an integer multiple of 90 degrees. Specifically, when the short-side direction (X direction) of the pixel 30 is set to 0 degrees, the tilt orientation in each domain is substantially 45 degrees in the first domain 31, substantially 135 degrees in the second domain 32, substantially 225 degrees in the third domain 33, and substantially 315 degrees in the fourth domain 34.

As shown in FIG. 3, the multiple pixels 30 of the liquid crystal display device 10 are arranged in the short direction of the pixel 30 (X direction) so that the alignment directions of adjacent domains in the short direction of the pixel 30 are the same. In FIG. 3, arrow 41 indicates the exposure direction of polarized radiation on a coating film formed using a liquid crystal alignment agent. Reference numeral 44 indicates the region corresponding to the fourth domain 34 of each pixel.

By forming the photo-alignment film in the liquid crystal display device 10 having the above configuration using polymer (P) having the partial structure represented by formula (1) above, it is possible to obtain a highly reliable liquid crystal display device that has high transmittance and is resistant to deterioration in liquid crystal alignment even after long-term backlight irradiation.

The liquid crystal display device 10 can be effectively applied to a variety of applications. For example, the liquid crystal display device 10 can be used as a variety of display devices, such as watches, portable game consoles, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, LCD televisions, and information displays.

The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples.

In the following examples and comparative examples, the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer, the imidization rate of the polyimide, and the epoxy equivalent were measured by the following methods.

[Weight average molecular weight (Mw) and number average molecular weight (Mn) of polymer]
Mw and Mn are values calculated as polystyrene measured by gel permeation chromatography under the following conditions.
Column: TSKgel GRCXLII, manufactured by Tosoh Corporation
Solvent: tetrahydrofuran (for polyorganosiloxanes and addition polymers), or N,N-dimethylformamide solution containing lithium bromide and phosphoric acid (for polyamic acid esters)
Temperature: 40℃
Pressure: 68 kgf/ ^cm2

[Imidization rate]
The polyimide solution was poured into pure water, and the resulting precipitate was thoroughly dried under reduced pressure at room temperature. The precipitate was then dissolved in deuterated dimethyl sulfoxide and subjected to ^1H -NMR measurement at room temperature using tetramethylsilane as a reference material. The imidization ratio was calculated from the obtained ^1H -NMR spectrum using the following mathematical formula (E-1).
Imidization rate (%)=(1−A ¹ /A ² ×α)×100 (E−1)
(In formula (E-1), ^A1 is the peak area derived from the proton of the NH group appearing at a chemical shift of around 10 ppm, ^A2 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 (polyamic acid).)

[Epoxy equivalent]
The epoxy equivalent was measured by the hydrochloric acid-methyl ethyl ketone method described in JIS C 2105.

The structural formula of the compound used in this example is shown below. For convenience, "compound represented by formula (X)" will be abbreviated as "compound (X)" below.

(Tetracarboxylic acid derivatives)

(diamine)

(Modifying carboxylic acid)

(Unsaturated Monomer)

(Additives)

1. Synthesis of Compound [Synthesis Example 1-1]
Compound (DA-1) was synthesized according to the following scheme.

Synthesis of Compound (DA-1-1) 16.5 g (100 mmol) of 4-nitrobenzaldehyde and 11.3 g (100 mmol) of cyanomalonic acid were dissolved in 500 ml of pyridine, and 25 ml of piperidine was added thereto. The mixture was then reacted at 80°C for 5 hours. After the reaction, the mixture was cooled to room temperature, and 300 ml of ethyl acetate was added, followed by 200 ml of hydrochloric acid, followed by separation. After separation with 300 ml of water twice, the solvent was distilled off using a rotary evaporator to obtain a solid. The obtained solid was stirred under reflux with 100 ml of water and 5 g of sodium hydroxide for 3 hours. After stirring, the pH was adjusted to 4 with hydrochloric acid, and the precipitated solid was collected by filtration, washed with water, and dried to obtain 20.3 g of compound (DA-1-1) as an intermediate.

Synthesis of Compound (DA-1-2) 2.61 g (10.0 mmol) of compound (DA-1-1) and 1.38 g (10.0 mmol) of 4-nitroaniline were dissolved in 50 ml of dichloromethane and cooled to 0°C. Next, 1.86 g (12.0 mmol) of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide and 0.61 g (4.99 mmol) of 4-dimethylaminopyridine were added, and the mixture was allowed to react overnight after returning to room temperature. Thereafter, the mixture was separated once with 50 ml of 1 N hydrochloric acid and three times with 50 ml of water, and the organic layer was distilled off using a rotary evaporator to obtain 3.27 g of compound (DA-1-2).

Synthesis of Compound (DA-1) 30 ml each of THF and water were added to 3.52 g (10.0 mmol) of compound (DA-1-2), and 10 equivalents of tin chloride were added thereto, followed by a reaction at 60°C for 2 hours. After the reaction, 50 ml of ethyl acetate was added, and the mixture was separated. The mixture was further separated twice with 50 ml of water, and the organic layer was distilled off with a rotary evaporator. The resulting solid was dissolved in 50 ml of THF, and 30 ml of ethanol and 10 ml of water were added thereto. The good solvent was slowly distilled off with a rotary evaporator, and the precipitated solid was collected by filtration and dried, yielding 2.48 g of compound (DA-1).

[Synthesis Example 1-2]
Compound (DA-3) was synthesized according to the following scheme.

Synthesis of Compound (DA-3-1) A solution of 30.2 g (120 mmol) of triethyl phosphonoacetate in 200 ml of dehydrated THF was added dropwise to 4.8 g (120 mmol) of sodium hydride and stirred at 0°C for 2 hours. A solution of 21.9 g (100 mmol) of 4'-nitro-2,2,2-trifluoroacetophenone in 100 ml of THF was added dropwise thereto, and the mixture was stirred at room temperature for 1 hour, followed by a reaction under reflux for 2 hours. After completion of the reaction, 300 ml of ethyl acetate was added, and the mixture was separated twice with saturated NH ₄ Cl solution and three times with water. The organic layer was evaporated using a rotary evaporator, and then stirred under reflux with 300 ml of water and 10 g of sodium hydroxide for 3 hours. After stirring, the mixture was adjusted to pH 4 with hydrochloric acid, and the precipitated solid was collected by filtration, washed with water, and dried to obtain 17.7 g of compound (DA-3-1) as an intermediate. Thereafter, compound (DA-3) was synthesized in the same manner as compound (DA-1-2) and compound (DA-1).

[Synthesis Example 1-3]
Compound (DA-4) was synthesized according to the following scheme.

Synthesis of Compound (DA-4-2) 2.51 g (10.0 mmol) of compound (DA-4-1), 3.85 g (50.0 mmol) of ammonium acetate, and 4.65 g (50.0 mmol) of aniline were added to 100 ml of ethanol and reacted under reflux for 3 hours. After the reaction, the solvent was distilled off using a rotary evaporator, and the mixture was dissolved in 50 ml of ethyl acetate and 50 ml of THF, and then separated three times with 1 N hydrochloric acid and three times with water. After distilling off the organic layer, the mixture was stirred under reflux for 3 hours with 100 ml of water and 3 g of sodium hydroxide. After stirring, the pH was adjusted to 4 with hydrochloric acid, and the precipitated solid was collected by filtration, washed with water, and dried to obtain 2.76 g of compound (DA-4-2) as an intermediate.
Thereafter, compound (DA-4) was synthesized in the same manner as in the synthesis of compounds (DA-1-2) and (DA-1).

[Synthesis Example 1-4]
Compound (M-1) was synthesized according to the following scheme.

Synthesis of Compound (M-1-2) 31.0 g (100 mmol) of compound (M-1-1), 76.0 g (500 mmol) of DBU, 87.8 mg (2.50 mmol) of Pd(PPh ₃ ) ₂ Cl ₂ , and 2.130 g (10.0 mmol) of 1,4-bis(diphenylphosphino)butane were dissolved in 200 ml of DMSO under a nitrogen atmosphere. Next, 7.01 g (100 mmol) of propiolic acid was added, and the mixture was allowed to react at 50°C for 5 hours. The reaction solution was then poured into 200 ml of ethyl acetate, and the mixture was separated twice with 200 ml of saturated sodium bicarbonate solution, twice with 200 ml of 1 N hydrochloric acid, and three times with 200 ml of water. The organic layer was distilled under reduced pressure to obtain 21.7 g of compound (M-1-2).

Synthesis of Compound (M-1-3) 3.00 g (10.1 mmol) of compound (M-1-2) was dissolved in 100 ml of dichloromethane and ice-cooled to 0°C. Next, 9 g of 47.0-49.0% hydrobromic acid was added and allowed to react for 5 hours. The reaction solution was slowly poured into a saturated aqueous sodium hydroxide solution and separated. The solution was further separated twice with 50 ml of 1 N hydrochloric acid and twice with 100 ml of water, and the organic layer was distilled off under reduced pressure. The resulting solid was purified by column chromatography to obtain 1.68 g of compound (M-1-3).

Synthesis of Compound (M-1) 10 ml of thionyl chloride and a catalytic amount of DMF were added to 1.13 g (3.00 mmol) of compound (M-1-3), and the mixture was reacted at 60°C for 2 hours. After the reaction, thionyl chloride was removed by distillation under reduced pressure. The resulting solid was dissolved in 20 ml of dehydrated THF to obtain solution A. Separately from solution A, 0.391 g (3.00 mmol) of 2-hydroxyethyl methacrylate and 0.500 g of triethylamine were dissolved in 10 ml of dehydrated THF and ice-cooled to 0°C. Solution A was added dropwise to the resulting solution, and the mixture was allowed to react overnight at room temperature. After the reaction, the reaction solution was separated twice with 1 N hydrochloric acid and three times with water, and the organic layer was removed by distillation under reduced pressure. The resulting viscous material was purified by column chromatography to obtain 1.03 g of compound (M-1).

[Synthesis Example 1-5]
Compound (M-2) was synthesized according to the following scheme.

Synthesis of Compound (M-2-2) Compound (M-2-2) was synthesized in the same manner as in the synthesis of compound (DA-3-1), except that the raw materials were changed.

Synthesis of Compound (M-2) 20 ml of thionyl chloride and a catalytic amount of DMF were added to 3.70 g (10.0 mmol) of compound (M-2-2), and the mixture was reacted at 60°C for 2 hours. After the reaction, thionyl chloride was removed by distillation under reduced pressure. The resulting solid was dissolved in 50 ml of dehydrated THF to give solution A. Separately, 1.90 g (10.0 mmol) of 4-hydroxyphenylmaleimide and 1.20 g of triethylamine were dissolved in 50 ml of dehydrated THF, and the mixture was ice-cooled to 0°C. Solution A was added dropwise to the mixture, and the mixture was allowed to react at room temperature overnight. After the reaction, the reaction solution was separated twice with 1 N hydrochloric acid and three times with water, and the organic layer was removed by distillation under reduced pressure. Furthermore, the resulting solid was dissolved in 50 ml of THF, and 30 ml of ethanol and 10 ml of water were added thereto. The good solvent was slowly distilled off using a rotary evaporator, and the precipitated solid was collected by filtration and dried to obtain 3.31 g of compound (M-2).

[Synthesis Example 1-6]
Compound (M-3) was synthesized according to the following scheme.

Synthesis of compound (M-3-2)
The methyl ester of compound (M-3-2) was synthesized in the same manner as in J. Am. Chem. Soc. 2001, 123, 40, 9918-9919, and then hydrolyzed in the same manner as in compound (DA-1-1) to obtain compound (M-3-2). Thereafter, the synthesis was carried out in the same manner as in compound (M-2).

[Synthesis Examples 1-7 and 1-8]
Compounds (M-4) and (M-5) were synthesized in the same manner as for compound (M-2), except that the raw materials were changed.

[Synthesis Example 1-9]
Compound (M-6) was synthesized according to the following scheme.

Synthesis of Compound (M-6-1) Compound (M-1-1) 15.46 g (50.0 mmol), methyl methacrylate 16.0 ml (150.0 mmol), P(o-tolyl) ₃ 1.52 g (5.00 mmol), iPr ₂ NEt 26.1 ml (150 mmol), palladium acetate 561 mg (2.50 mmol), DMF 250 ml were added, and the atmosphere was thoroughly purged with nitrogen. The temperature was raised to 100 ° C and the reaction was carried out for 6 hours. After confirming the disappearance of the raw materials by LC, the mixture was cooled to room temperature. After cooling, 200 ml of ethyl acetate was added, the mixture was stirred at room temperature for a while, and the precipitate was removed by filtration. 200 ml of hexane was added to the filtrate, and the mixture was washed twice with 100 ml of 1 N HCl, twice with 100 ml of distilled water, and once with 100 ml of saturated saline. The organic layer was dried over anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure using a rotary evaporator and an oil pump. The resulting solid was stirred under reflux for 3 hours with 300 ml of water and 5 g of sodium hydroxide. After stirring, the pH was adjusted to 4 with hydrochloric acid, and the precipitated solid was collected by filtration, washed with water, and dried to obtain 17.2 g of compound (DA-6-2) as an intermediate. Thereafter, compound (M-6) was synthesized in the same manner as compound (M-2).

[Synthesis Example 1-10]
Compound (M-7) was synthesized in the same manner as compound (M-6), except that the raw materials were changed.

2. Polymer synthesis <Synthesis of polyamic acid>
[Synthesis Example 2-1]
50 parts by mole of 2,3,5-tricarboxycyclopentylacetic dianhydride (compound (T-1)), 50 parts by mole of 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 70 parts by mole of compound (DA-1), and 30 parts by mole of compound (DA-2) were dissolved in N-methyl-2-pyrrolidone (NMP), and the mixture was allowed to react at 40°C for 3 hours to obtain a solution containing 10% by mass of polymer (P-1).

[Synthesis Examples 2-4, 2-11, 2-12 and 2-13, Comparative Synthesis Examples 3 and 4]
Solutions containing polymers (P-10), (PAA-S), (PAA-1), (PAA-2), (P-13), and (P-14) were obtained by performing the same operation as in Synthesis Example 2-1 above, except that the types and amounts of the tetracarboxylic acid derivatives and diamines used were changed as shown in Table 1 below. In Table 1, the numerical values for the tetracarboxylic acid derivatives indicate the proportion (mol %) of each compound used relative to the total amount of the tetracarboxylic acid derivatives used in synthesizing the polymers. The numerical values for the diamines indicate the proportion (mol %) of each compound used relative to the total amount of the diamines used in synthesizing the polymers.

<Synthesis of Polyimide>
[Synthesis Example 2-2]
100 moles of 2,3,5-tricarboxycyclopentylacetic dianhydride (compound (T-1)), 20 moles of compound (DA-2), and 80 moles of compound (DA-3) were dissolved in N-methyl-2-pyrrolidone (NMP) and reacted at 40°C for 3 hours to obtain a solution containing 10% by mass of polyamic acid. To the obtained polyamic acid solution, 1 mole of pyridine and acetic anhydride were added per mole of the tetracarboxylic dianhydride used in the polymerization, and a dehydration ring-closing reaction was carried out at 100°C for 8 hours. After completion of the reaction, the reaction mixture was poured into a large excess of methanol to precipitate the reaction product. The recovered precipitate was washed with methanol and then dried under reduced pressure at 40°C for 15 hours to obtain polymer (P-2). The imidization rate of the obtained polymer (P-2) was 68%.

<Synthesis of Polyamic Acid Ester>
[Synthesis Example 2-3]
22.42 g of the compound represented by the following formula (TA-3), 100 mL of tetrahydrofuran, and 0.79 g of pyridine were placed in a 200 mL three-neck flask equipped with a nitrogen inlet tube, a reflux condenser, and a thermometer, and the mixture was stirred under a nitrogen stream to form a suspension. 15.14 g of β-methallyl alcohol was added to this suspension, and the mixture was stirred at room temperature for 2 hours. The reaction was further carried out at 60°C for 8 hours, yielding a colorless, transparent solution. This reaction solution was concentrated under reduced pressure at 60°C and further dried in vacuo to obtain 36.84 g of a mixture of a compound represented by the following formula (DE-1a) and a compound represented by the following formula (DE-1b) (hereinafter referred to as "mixture (DE-1a/b)").

Next, 18.42 g of the mixture (DE-1a/b) and 100 mL of toluene were placed in a 100 mL recovery flask equipped with a nitrogen inlet tube and a reflux condenser, and the mixture was stirred at 80°C for 30 minutes. The mixture was then cooled to room temperature with stirring, and further stirred at room temperature for 30 minutes. The resulting suspension was filtered and washed twice with 5 mL of toluene. The resulting solid was dried in vacuo at 60°C, yielding 15.47 g of compound (DE-1a) as a white powder (yield 84%).

A 500 mL three-neck flask equipped with a nitrogen inlet tube, a reflux condenser, and a thermometer was charged with 14.74 g of compound (DE-1a), 80 mL of heptane, and 0.032 g of pyridine, and the mixture was stirred at 75°C under a nitrogen stream. 14.28 g of thionyl chloride was slowly added dropwise over 20 minutes, and foaming due to the progress of the reaction was confirmed. After the completion of the addition, the mixture was reacted at 75°C for 2 hours, yielding a colorless, transparent solution. This reaction solution was concentrated under reduced pressure at 60°C, and excess thionyl chloride was distilled off. 80 mL of heptane was added to the resulting liquid, and the mixture was stirred at room temperature. The precipitated insoluble matter was removed by filtration. The filtrate was concentrated under reduced pressure at 60°C and further dried under high vacuum at 60°C for 4 hours, yielding 15.89 g of a colorless, transparent liquid compound represented by the following formula (DE-1a) (yield: 98%).

100 mol parts of compound (T-3), 70 mol parts of compound (DA-2), 30 mol parts of compound (DA-4), 57 g of NMP, and 24 g of triethylamine were placed in a 50 mL three-neck flask equipped with a nitrogen inlet tube and a thermometer, and the mixture was cooled to approximately 10°C. 83 g of DMT-MM, a triazine-based dehydration condensation agent, was added, and the mixture was allowed to react at room temperature for 24 hours under a nitrogen stream. The resulting polymerization solution was diluted with NMP and slowly poured into methanol with stirring to allow coagulation. The precipitated solid was recovered, washed twice in methanol with stirring, and vacuum dried at 60°C to obtain a white powder polyamic acid ester (hereinafter referred to as "polymer (P-3)"). The number-average molecular weight Mn of this polymer was 14,000, and the molecular weight distribution Mw/Mn was 2.8.

<Synthesis of Polyorganosiloxane>
[Synthesis Example 2-5]
In a reaction vessel equipped with a stirrer, thermometer, dropping funnel, and reflux condenser, 100.0 g of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 500 g of methyl isobutyl ketone, and 10.0 g of triethylamine were mixed at room temperature. Next, 100 g of pure water was slowly added dropwise, and the mixture was stirred at 80 °C for 6 hours. The organic layer was then removed and washed with a 0.2% by mass aqueous ammonium nitrate solution until the water after washing became neutral, and then concentrated to obtain a polyorganosiloxane (EPS-1) having epoxy groups as a viscous, transparent liquid. The Mw of this polyorganosiloxane (EPS-1) having epoxy groups was 2,200, and the epoxy equivalent was 186 g/mol.
Next, a 100 mL three-neck flask was charged with 8.0 g of the epoxy group-containing polyorganosiloxane (EPS-1) obtained above, 26 g of methyl isobutyl ketone, 15.3 g of compound (CA-1), and 0.10 g of trade name "UCAT 18X" (quaternary amine salt manufactured by San-Apro Co., Ltd.), and the reaction was carried out with stirring at 80 ° C. for 12 hours. After completion of the reaction, the reaction mixture was poured into methanol to collect the resulting precipitate, which was dissolved in ethyl acetate to obtain a solution. The solution was washed with water three times, and the solvent was then distilled off to obtain 23.2 g of polymer (P-4) as a white powder. The weight average molecular weight Mw of this polymer (P-4) was 14,100.

<Synthesis of Addition Polymer>
[Synthesis Example 2-6]
Under nitrogen, 9.0 g of compound (M-1), 3.0 g of compound (M-9), and 1.8 g of compound (M-10) were added to a 100 mL two-neck flask as polymerization monomers, 0.70 g of 2,2'-azobis(2,4-dimethylvaleronitrile) as a radical polymerization initiator, 0.20 g of 2,4-diphenyl-4-methyl-1-pentene as a chain transfer agent, and 50 ml of N-methyl-2-pyrrolidone (NMP) as a solvent, and the mixture was polymerized at 70 ° C. for 6 hours. After reprecipitation in methanol, the precipitate was filtered and dried in vacuum at room temperature for 8 hours to obtain the target polymer (P-5). The weight average molecular weight Mw measured in polystyrene equivalent terms by GPC was 42,000, and the molecular weight distribution Mw/Mn was 2.1.

[Synthesis Examples 2-7 to 2-10, Comparative Synthesis Examples 1, 2, and 5]
Polymers (P-6) to (P-9), (P-11), (P-12), and (P-15) were obtained by the same procedure as in Synthesis Example 2-6 above, except that the types and amounts of the polymerizable monomers used were changed as shown in Table 2. In Table 2, the numerical values for the polymerizable monomers indicate the proportion (mol %) of each compound used relative to the total amount of the polymerizable monomers used in the synthesis of the polymer.

3. Preparation and evaluation of liquid crystal alignment agent and liquid crystal display device [Example 1]
(1) Preparation of liquid crystal aligning agent 5 parts by mass of the polymer (P-1) obtained in Synthesis Example 2-1, 100 parts by mass of the polymer (PAA-1) obtained in Synthesis Example 2-12, and 10 parts by mass of the compound (ADD-1) were added as a solvent to a container, and a solution with a solvent composition of NMP/BC = 50/50 (mass ratio) and a solids concentration of 3.5% by mass was prepared. This solution was filtered through a filter with a pore size of 1 μm to prepare a liquid crystal aligning agent (AL-1).

(2) Production of an optical FFS-type liquid crystal display element A glass substrate was prepared, which had two systems of metal electrodes (electrode A and electrode B) made of chromium patterned in a comb-like shape, and which allowed voltage application to electrode A and electrode B independently. This glass substrate was paired with an opposing glass substrate having no electrodes, and the liquid crystal alignment agent (AL-1) prepared above was applied to the surface of the glass substrate having the electrodes and one surface of the opposing glass substrate using a spin coater. Next, the substrate was pre-baked for 1 minute on a hot plate at 80°C, and then heated (post-baked) for 1 hour in an oven at 200°C with the interior of the oven substituted with nitrogen, thereby forming a coating film with an average film thickness of 0.08 μm.
This procedure was repeated to obtain a pair (two glass substrates) with a coating film on the transparent conductive film. The coating film obtained above was subjected to a photoalignment treatment by irradiating the substrate normal direction with 2,000 J/ ^m² of polarized ultraviolet light containing a 313 nm emission line using an Hg-Xe lamp and a Glan-Taylor prism. The irradiation dose was measured using an actinometer measuring at a wavelength of 313 nm.
Next, for one of the pair of substrates on which the liquid crystal alignment film was formed, an epoxy resin adhesive containing 3.5 μm diameter aluminum oxide spheres was applied to the outer edge of the surface bearing the liquid crystal alignment film, and the pair of substrates were then superimposed and pressed together with the liquid crystal alignment film surfaces facing each other, and the adhesive was allowed to harden. Next, a liquid crystal composition (MLC-6221, manufactured by Merck & Co.) was filled between the pair of substrates through the liquid crystal injection port, and the liquid crystal injection port was sealed with an acrylic photocurable adhesive to obtain a liquid crystal cell. Furthermore, polarizing plates were attached to both outer surfaces of the substrates in the liquid crystal cell so that the polarization directions of the two polarizing plates were perpendicular to each other.

(3) Evaluation of Backlight Reliability (BL Reliability) The liquid crystal display device prepared above was left standing in front of a high-brightness backlight of 27,000 cd/ ^m² for 500 hours, and the change in characteristics before and after irradiation with the backlight was evaluated by the method (3A) below.
(3A) Evaluation of BL Reliability by Retardation Change Rate The retardation of the liquid crystal display element was measured using an Axoscan manufactured by Optoscience, and the change rate α of retardation before and after backlight irradiation was calculated using the following formula (z-1). The smaller the change rate α, the less likely the liquid crystal display element is to have an afterimage even after long-term operation, and the better the BL reliability. When the change rate α was 0.5% or less, it was rated as "best (◎)", when it was greater than 0.5% and less than 1%, it was rated as "good (○)", when it was greater than 1% and less than 2%, it was rated as "fair (△)", and when it was greater than 2%, it was rated as "poor (×)".
α=Δθ/θ1...(z-1)
(In formula (z-1), Δθ represents the difference in retardation before and after irradiation, and θ1 represents the retardation before irradiation.)
As a result, this example was evaluated as "good (◯)".

[Examples 2 and 3 and Comparative Example 3]
Each liquid crystal alignment agent was prepared in the same manner as in Example 1, except that the formulation of the liquid crystal alignment agent was changed as shown in Table 3. In addition, using the prepared liquid crystal alignment agent, an optical FFS-type liquid crystal display element was manufactured in the same manner as in Example 1, and evaluations were performed in the same manner as in Example 1. The results are shown in Table 3.

[Example 4]
(1) Preparation of liquid crystal aligning agent To a container containing 50 parts by mass of the polymer (P-4) obtained in Synthesis Example 2-5, 100 parts by mass of the polymer (PAA-1) obtained in Synthesis Example 2-12, and 5 parts by mass of the compound (ADD-4), NMP and butyl cellosolve (BC) were added as a solvent to obtain a solution with a solvent composition of NMP/BC = 50/50 (mass ratio) and a solids concentration of 3.5% by mass. This solution was filtered through a filter with a pore size of 1 μm to prepare a liquid crystal aligning agent (AL-4).

(2) Manufacturing of vertical optical LCD devices (UV2A)
The liquid crystal alignment agent (AL-4) prepared in (1) above was applied to the transparent electrode surface of a glass substrate with a transparent electrode made of an ITO film using a spinner, pre-baked on a hot plate at 80 ° C for 1 minute, and then baked at 200 ° C for 40 minutes to form a coating film with a thickness of 0.08 μm. Next, using a Hg-Xe lamp and a Glan-Taylor prism, the surface of this coating film was irradiated with 200 J/m ² of polarized ultraviolet light containing a 313 nm emission line at room temperature from a direction tilted 40 ° relative to the substrate normal. The same operation was repeated to create a pair (two substrates) on which a liquid crystal alignment film was formed.
An epoxy resin adhesive containing 3.5 μm diameter aluminum oxide spheres was applied by screen printing to the outer periphery of the surface bearing the liquid crystal alignment film on one of the two substrates. The pair of substrates were then placed with the liquid crystal alignment film facing each other. The pair of substrates were then pressed together so that the optical axes of the UV light irradiated on each substrate were antiparallel to the substrate surfaces. The adhesive was then thermally cured at 150°C for 1 hour. Next, a liquid crystal composition (MLC-6608, manufactured by Merck & Co.) was filled into the gap between the substrates through the liquid crystal injection port, which was then sealed with an epoxy adhesive to obtain a liquid crystal cell. Furthermore, to eliminate flow alignment during liquid crystal injection, the liquid crystal cell was heated to 150°C and then slowly cooled to room temperature. Next, polarizing plates were attached to both outer surfaces of the liquid crystal cell so that their polarization directions were perpendicular to each other and formed a 45° angle with the optical axis of the UV light irradiated during liquid crystal alignment film formation.

(3) Evaluation of BL Reliability The liquid crystal display element prepared above was left standing in front of a high-brightness backlight of 27,000 cd/ ^m2 for 500 hours, and the change in characteristics before and after irradiation with the backlight was evaluated by the method described in (3B) below.
(3B) Evaluation of BL Reliability Due to Tilt Return The pretilt angle of the liquid crystal was measured using an Optipro manufactured by Shintech Co., Ltd., and the BL reliability was evaluated by comparing the pretilt angles before and after backlight irradiation. A difference in pretilt angle between before and after irradiation of 0.1 degrees or less was evaluated as "best (◎)", a difference between more than 0.1 degrees and less than 0.5 degrees was evaluated as "good (○)", a difference between more than 0.5 degrees and less than 1.0 degrees was evaluated as "fair (△)", and a difference greater than 1.0 degrees was evaluated as "poor (×)". As a result, in this example, the evaluation was "fair (△)".

[Examples 5 to 10 and Comparative Examples 1, 2, 4, and 5]
Each liquid crystal alignment agent was prepared in the same manner as in Example 4, except that the formulation of the liquid crystal alignment agent was changed as shown in Table 3. Furthermore, using the prepared liquid crystal alignment agent, a vertical light type liquid crystal display element was manufactured in the same manner as in Example 4, and evaluations were performed in the same manner as in Example 4. The results are shown in Table 3.

From the above results, in Examples 1 to 10, which used a liquid crystal aligning agent containing polymer (P), the liquid crystal alignment property was good even after long-term irradiation with backlight, and the BL reliability was excellent. In particular, in Example 7, which blended as polymer (P-7) in which R ^β in the above formula (1) was a trimethylsilyl group, Example 8, which blended as polymer (P-8) in which R ^β was an ethyl group, Example 9, which blended as polymer (P-9) in which R ^β was a methyl group, and Example 10, which blended as polymer (P-10) in which R ^β was a methyl group, the difference in pretilt angle before and after backlight irradiation was small, and the BL reliability was evaluated as good (○) or best (◎).

In contrast, in Comparative Examples 1 to 5, which used a liquid crystal alignment agent that did not contain polymer (P), the BL reliability was evaluated as poor. It is presumed that the reason why BL reliability could not be evaluated in Comparative Example 5, which used polymer (P-15) in which an ester group (-COOMe) was introduced at the β-position of the cinnamate structure, is that the ester group (-COOMe) is decarboxylated by post-baking at high temperatures, which has an adverse effect.

[Example 11]
(1) Preparation of Liquid Crystal Alignment Agent Using the polymer (P-9) obtained in Synthesis Example 2-10, a liquid crystal aligning agent (AL-11) was prepared using the same composition and preparation method as in Example 9.

(2) Fabrication and Evaluation of Liquid Crystal Display Devices A liquid crystal display device corresponding to Figure 1 was fabricated. First, a TFT substrate having pixel electrodes and a CF substrate having a counter electrode were prepared. Solid electrodes without slits were used as the pixel electrodes of the TFT substrate and the counter electrode of the CF substrate. The liquid crystal alignment agent (AL-11) prepared in (1) above was applied to the electrode-positioned surfaces of the TFT substrate and the CF substrate by spin casting. This was pre-baked at 80°C for 1 minute and then post-baked at 230°C for 40 minutes to achieve a final film thickness of 120 nm. Next, scan exposure was performed on the coating film (liquid crystal alignment film) formed on the TFT substrate. Scan exposure was performed a total of four times using 313 nm linearly polarized light at an intensity of 20 mJ/ ^cm² , as shown in Figure 2, so that four domains with different alignment orientations of liquid crystal molecules were formed within one pixel. On the other hand, no exposure was performed on the liquid crystal alignment film formed on the CF substrate using the liquid crystal alignment agent (AL-11).

Next, nematic liquid crystal with negative dielectric anisotropy was dropped onto the liquid crystal alignment film-formed surface of the TFT substrate, and a thermosetting epoxy resin was applied as a sealant to the outer edge of the CF substrate. The TFT substrate and CF substrate were then bonded together with their alignment film surfaces facing inward. The epoxy resin was then cured by heating at 130°C for 1 hour to obtain a liquid crystal cell. The transmittance of the resulting liquid crystal cell was measured when driven at 6V AC. The transmittance was calculated by simulation using an Expert LCD manufactured by LinkGlobal21. The calculation conditions were liquid crystal properties: Δε = 3, Ne = 1.6, No = 1.5, cell gap: 3.2 μm, and pretilt angle: measured values (TFT substrate side: 88.0°, CF substrate side: 90.0°), and the transmittance was evaluated from the results at an applied voltage of 6V. When the calculated transmittance was less than 0.275, it was evaluated as "Fair (△)", when it was 0.275 or more but less than 0.280, it was evaluated as "Good (○)", when it was 0.280 or more but less than 0.285, it was evaluated as "Excellent (◎)", and when it was 0.285 or more, it was evaluated as "Best (◎◎)". Furthermore, as in Example 4, the liquid crystal display device fabricated above was left standing for 500 hours in front of a high-brightness backlight of 27,000 cd/ ^m² , and the change in characteristics (BL reliability due to tilt return) before and after irradiation with the backlight was evaluated by the method (3B) above. The results are shown in Table 4.

[Comparative Example 6 and Reference Example 1]
Each liquid crystal aligning agent was prepared in the same manner as in Example 11, except that the polymer used was changed as shown in Table 4. Furthermore, using the prepared liquid crystal aligning agent, a liquid crystal display device was manufactured in the same manner as in Example 11, and evaluations were performed in the same manner as in Example 11. The results are shown in Table 4.

As shown in Table 4, Example 11, which used a liquid crystal alignment agent containing polymer (P), had high transmittance and excellent BL reliability. In contrast, Comparative Example 6, which used a liquid crystal alignment agent that did not contain polymer (P), had inferior transmittance and BL reliability compared to Example 11. Furthermore, Reference Example 1, which used a polymer containing a partial structure with a substituent (methyl group) at the α-position instead of the β-position of the carbonyl carbon in the above formula (1), was rated as "◎" for transmittance and "○" for BL reliability based on tilt return. These results demonstrate that a liquid crystal alignment agent containing polymer (P) can further improve the transmittance and BL reliability of liquid crystal display devices.

10...Liquid crystal display device, 11...First substrate, 12...Second substrate, 13...Liquid crystal layer, 14...Transparent substrate, 15...Pixel electrode, 16...Transparent substrate, 17...Black matrix, 18...Color filter, 19...Counter electrode, 22...First alignment film, 23...Second alignment film, 24...Spacer, 25...Sealing material, 30...Pixel, 31...First domain, 32...Second domain, 33...Third domain, 34...Fourth domain, 35...Liquid crystal molecules, 36...Wiring

Claims (15)

A liquid crystal aligning agent comprising a polymer (P) having a partial structure represented by the following formula (1):
(In formula (1), R ^β represents a monovalent hydrocarbon group having 1 to 10 carbon atoms, a cyano group, a nitro group, a chlorine atom, a bromine atom, an iodine atom, —SiR ² R ³ R ⁴ , —P(═O)R ² R ³ , —C≡CR ² or —NR ² R ³ ; a monovalent group R ω1 in which any methylene group in a monovalent hydrocarbon group having 2 to 10 carbon atoms has been replaced with —O—, —S— or —NR ² —; or a monovalent group in which any hydrogen atom in the group R ^ω1 or ^the monovalent hydrocarbon group having 1 to 10 carbon atoms has been replaced with a halogen atom, a cyano group, a hydroxyl group, an amino group, a thiol group or a nitro group. ^{R α} represents a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, a cyano group, a nitro group, a halogen atom, —SiR ² R ³ R ⁴ , -P(=O)R ² R ³ , -COOR ² , -C≡CR ² or -NR ² R ³ ; a monovalent group R ^ω2 in which any methylene group in a monovalent hydrocarbon group having 2 to 10 carbon atoms is replaced with -O-, -S- or -NR ² -; or a monovalent group in which any hydrogen atom in the group R ^ω2 or a monovalent hydrocarbon group having 1 to 10 carbon atoms is replaced with a halogen atom, a cyano group, a hydroxyl group, an amino group, a thiol group or a nitro group. R ² , R ³ and R ⁴ are each independently a hydrogen atom or a monovalent organic group. X ¹ is an oxygen atom or -NR ⁵ -. R ⁵ is a hydrogen atom or a monovalent organic group. R ¹ is a substituent. n is an integer of 0 to 4. m is 0 or 1. "*" represents a bond. The liquid crystal aligning agent according to claim 1, wherein the polymer (P) has a partial structure represented by the above formula (1) in its side chain. The liquid crystal aligning agent according to claim 2, wherein the polymer (P) is at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane, and addition polymer. The liquid crystal aligning agent according to claim 1, wherein the polymer (P) has a partial structure represented by the above formula (1) in its main chain. The liquid crystal aligning agent according to claim 4, wherein the polymer (P) is at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide. The liquid crystal aligning agent according to claim 1, wherein the polymer (P) is at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane, and addition polymer. The liquid crystal aligning agent according to claim 1, wherein R ^α is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a cyano group, or a monovalent group in which any methylene group in a monovalent hydrocarbon group having 2 to 10 carbon atoms is replaced with -O-, -S-, or -NR ² - (wherein R ² is a hydrogen atom or a monovalent organic group). The liquid crystal aligning agent according to claim 1, wherein R ^β is an alkyl group having 1 to 6 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, a trialkylsilyl group, a cyano group, a bromine atom, an iodine atom, -NR ¹² R ¹³ (wherein R ¹² and R ¹³ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms), or a monovalent group in which any methylene group in a monovalent hydrocarbon group having 2 to 10 carbon atoms is replaced with -O-, -S- or -NR ² - (wherein R ² is a hydrogen atom or a monovalent organic group). The liquid crystal aligning agent according to claim 1, further comprising a polymer (Q) that does not have the partial structure represented by formula (1). The liquid crystal aligning agent according to claim 9, wherein the polymer (Q) is at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, and addition polymer. A method for producing a liquid crystal alignment film, comprising the steps of applying the liquid crystal aligning agent according to any one of claims 1 to 10 onto a substrate to form a coating film, and irradiating the coating film with light. A liquid crystal alignment film formed using the liquid crystal alignment agent according to any one of claims 1 to 10. A liquid crystal element comprising the liquid crystal alignment film according to claim 12. A liquid crystal display device having a plurality of pixels,
a first substrate;
a second substrate facing the first substrate;
a liquid crystal layer provided between the first substrate and the second substrate and containing liquid crystal molecules;
a first alignment film formed on the first substrate to align the liquid crystal molecules;
a second alignment film formed on the second substrate to align the liquid crystal molecules;
Equipped with
at least one of the first alignment film and the second alignment film is a photo-alignment film;
Each pixel among the plurality of pixels has a first alignment region, a second alignment region, a third alignment region, and a fourth alignment region as regions in which the alignment orientations of the liquid crystal molecules are different from one another, and the first alignment region, the second alignment region, the third alignment region, and the fourth alignment region are arranged side by side in a longitudinal direction of the pixel,
a difference between any two of the orientation orientation of the first orientation region, the orientation orientation of the second orientation region, the orientation orientation of the third orientation region, and the orientation orientation of the fourth orientation region is approximately equal to an integer multiple of 90 degrees;
the plurality of pixels are arranged side by side in a short-side direction of the pixels such that the alignment directions of the alignment regions adjacent to each other in the short-side direction of the pixels are the same;
in each of the first alignment region, the second alignment region, the third alignment region, and the fourth alignment region, one of a pretilt angle defined by the first alignment film and a pretilt angle defined by the second alignment film is less than 90 degrees, and the other is substantially 90 degrees;
A liquid crystal display device, wherein the photo-alignment film is formed using the liquid crystal aligning agent according to any one of claims 1 to 8. A polymer having a partial structure represented by the following formula (1):
(In formula (1), R ^β represents a monovalent hydrocarbon group having 1 to 10 carbon atoms, a cyano group, a nitro group, a chlorine atom, a bromine atom, an iodine atom, —SiR ² R ³ R ⁴ , —P(═O)R ² R ³ , —C≡CR ² or —NR ² R ³ ; a monovalent group R ω1 in which any methylene group in a monovalent hydrocarbon group having 2 to 10 carbon atoms has been replaced with —O—, —S— or —NR ² —; or a monovalent group in which any hydrogen atom in the group R ^ω1 or ^the monovalent hydrocarbon group having 1 to 10 carbon atoms has been replaced with a halogen atom, a cyano group, a hydroxyl group, an amino group, a thiol group or a nitro group. ^{R α} represents a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, a cyano group, a nitro group, a halogen atom, —SiR ² R ³ R ⁴ , -P(=O)R ² R ³ , -COOR ² , -C≡CR ² or -NR ² R ³ ; a monovalent group R ^ω2 in which any methylene group in a monovalent hydrocarbon group having 2 to 10 carbon atoms is replaced with -O-, -S- or -NR ² -; or a monovalent group in which any hydrogen atom in the group R ^ω2 or a monovalent hydrocarbon group having 1 to 10 carbon atoms is replaced with a halogen atom, a cyano group, a hydroxyl group, an amino group, a thiol group or a nitro group. R ² , R ³ and R ⁴ are each independently a hydrogen atom or a monovalent organic group. X ¹ is an oxygen atom or -NR ⁵ -. R ⁵ is a hydrogen atom or a monovalent organic group. R ¹ is a substituent. n is an integer of 0 to 4. m is 0 or 1. "*" represents a bond.