TWI854033B - Liquid crystal alignment agent, liquid crystal alignment film, liquid crystal element, polymer and compound - Google Patents

Abstract

The present invention provides a liquid crystal alignment agent that can form a liquid crystal alignment film with good coating uniformity and excellent pre-tilt angle characteristics. The liquid crystal alignment agent contains a polymer (A), and the polymer (A) has a structural unit derived from at least one monomer selected from the group consisting of a compound represented by formula (1) and a compound represented by formula (2). In the formula, ^R1 and ^R2 represent that one of ^R1 and ^R2 is a monovalent group having a polymerizable group, and the other is a hydrogen atom or a monovalent organic group, or ^R1 and ^R2 are combined with each other to form a ring structure together with the nitrogen atom to which ^R1 and ^R2 are bonded. The ring structure has a polymerizable carbon-carbon unsaturated bond. ^A1 is a monovalent organic group, and ^A2 is a hydroxyl group or a monovalent organic group. Satisfies 0≦n1+n2≦8.

Description

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

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

The liquid crystal element includes a liquid crystal alignment film that aligns liquid crystal molecules in a certain direction. Generally, the liquid crystal alignment film is formed by coating a liquid crystal alignment agent made by dissolving a polymer component in an organic solvent on a substrate, and preferably heating the substrate. Polyamide or soluble polyimide has been used as a polymer component of the liquid crystal alignment agent in terms of excellent mechanical strength, liquid crystal alignment, and affinity with liquid crystal.

As a method of imparting liquid crystal alignment ability to a polymer film formed by a liquid crystal alignment agent, a photoalignment method has been proposed as a technology to replace the rubbing method. The photoalignment method is a method of imparting anisotropy to a radiation-sensitive organic film formed on a substrate by irradiating the film with polarized or non-polarized radiation, thereby controlling the alignment of the liquid crystal.

As a liquid crystal alignment agent for forming a liquid crystal alignment film by a photoalignment method, there is provided a liquid crystal alignment agent containing a polymer having a main skeleton different from polyamide and soluble polyimide (for example, refer to Patent Document 1 or Patent Document 2). Patent Document 1 discloses a photoalignment composition containing a polymer having a maleic anhydride structure and a reaction product of a primary amine compound having a photoalignment group. Patent Document 2 discloses a photoalignment composition containing a first polymer having poly(maleimide) or poly(maleimide-styrene) as a main chain and a photosensitive group introduced into a side chain, and a second polymer having a long-chain alkyl group in the side chain. [Prior Art Document] [Patent Document]

[Patent Document 1] Korean Patent Publication No. 2015-138548 [Patent Document 2] Japanese Patent Publication No. 2962473

[Problems to be solved by the invention] The angle (pre-tilt angle) between the long axis of the liquid crystal molecules and the substrate surface greatly affects the display characteristics of the liquid crystal element. The inventors and others have made the following attempts: the liquid crystal alignment is controlled in such a way that the long axis of the liquid crystal molecules is tilted at an appropriate angle relative to the vertical direction (for example, the pre-tilt angle is 89 degrees or less) to obtain a liquid crystal element with higher precision than before. However, it was found that when the liquid crystal alignment film is formed using the alignment film material of Patent Document 1 or Patent Document 2, the long axis of the liquid crystal molecules cannot be sufficiently tilted relative to the vertical direction, and the pre-tilt angle is higher than the desired angle.

In recent years, in the heating step during film formation, it is sometimes required to use a low-boiling point solvent as a solvent component of the liquid crystal alignment agent for the purpose of being able to perform low-temperature calcination. If the polymer component is not uniformly dissolved in the solvent, there is a concern that the liquid crystal alignment film formed on the substrate will be unevenly coated and a flat film cannot be formed (poor coating uniformity). In this case, there is a concern that the product yield will be reduced or the display performance such as the liquid crystal alignment or electrical characteristics will be affected.

Furthermore, when the liquid crystal alignment film is formed by low-temperature calcination, the pre-tilt angle of the liquid crystal alignment film may deviate from the pre-tilt angle of the liquid crystal alignment film obtained by high-temperature calcination (for example, heating treatment at a temperature of about 230°C to 250°C). This deviation of the pre-tilt angle caused by the difference in heating temperature during film formation (hereinafter also referred to as "post-baking margin") will affect the display quality of the liquid crystal element, so it is desired to be as small as possible.

The present invention is made in view of the above situation, and its main purpose is to provide a liquid crystal alignment agent that can form a liquid crystal alignment film with good coating uniformity and excellent pre-tilt angle characteristics. [Means for solving the problem]

In order to solve the above-mentioned problem, the inventors of the present invention used a polymer having a specific ring structure as a polymer component of a liquid crystal alignment agent, and found that the above-mentioned problem can be solved. Specifically, according to the present invention, the following means are provided.

[1] A liquid crystal alignment agent comprising a polymer (A), wherein the polymer (A) has a structural unit derived from at least one monomer selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2), wherein: (In formula (1) and formula (2), ^R1 and ^R2 represent that one of ^R1 and ^R2 is a monovalent group having a polymerizable group and the other is a hydrogen atom or a monovalent organic group, or ^R1 and ^R2 are combined with each other to form a ring structure together with the nitrogen atom to which ^R1 and ^R2 are bonded; wherein the ring structure has a polymerizable carbon-carbon unsaturated bond; ^A1 is a monovalent organic group, ^A2 is a hydroxyl group or a monovalent organic group; n1 and n2 are each independently an integer satisfying 0≦n1+n2≦8). [2] A liquid crystal alignment film formed using the liquid crystal alignment agent of [1]. [3] A liquid crystal element comprising the liquid crystal alignment film of [2]. [4] A polymer having a structural unit derived from at least one monomer selected from the group consisting of a compound represented by the formula (1) and a compound represented by the formula (2). [5] A compound represented by the formula (1). [6] A compound represented by the formula (2). [Effects of the Invention]

By making the liquid crystal alignment agent contain the polymer (A), a liquid crystal alignment agent with good coating uniformity can be obtained. In addition, by using the liquid crystal alignment agent to form a liquid crystal alignment film, the tilt angle of the liquid crystal molecules relative to the vertical direction can be sufficiently increased, and the deviation of the pre-tilt angle caused by the difference in heating temperature during film formation can be reduced. That is, according to the liquid crystal alignment agent, a liquid crystal alignment film with excellent pre-tilt angle characteristics can be formed.

The following is a detailed description of matters related to the present invention. Liquid crystal alignment agent The liquid crystal alignment agent disclosed herein contains a polymer (A) having a structural unit U1 derived from at least one monomer (R1) selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2). [Chemical 2] (In formula (1) and formula (2), ^R1 and ^R2 represent that one of ^R1 and ^R2 is a hydrogen atom or a monovalent organic group and the other is a monovalent group having a polymerizable group, or ^R1 and ^R2 are bonded to each other to form a ring structure together with the nitrogen atom to which ^R1 and ^R2 are bonded; wherein the ring structure has a polymerizable carbon-carbon unsaturated bond; ^A1 is a monovalent organic group, ^A2 is a hydroxyl group or a monovalent organic group; n1 and n2 are each independently an integer satisfying 0≦n1+n2≦8)

<Polymer (A)> (Structural unit U1) In the above formula (1) and formula (2), the monovalent organic group of ^A1 and ^A2 includes: a monovalent hydrocarbon group having 1 to 40 carbon atoms, a group in which at least one methylene group of the hydrocarbon group is substituted by -O-, -CO-, -COO-, ^-NR10- or ^-CONR10- (wherein ^R10 is a hydrogen atom or a monovalent hydrocarbon group) (hereinafter also referred to as "group α"), and a monovalent hydrocarbon group having 1 to 40 carbon atoms or a group in which at least one hydrogen atom of the group α is substituted by a fluorine atom or a cyano group.

Here, in this specification, "alkyl" means chain alkyl, alicyclic alkyl and aromatic alkyl. The so-called "chain alkyl" refers to a straight chain alkyl and a branched alkyl that does not contain a ring structure in the main chain but consists only of a chain structure. Among them, it may be saturated or unsaturated. The so-called "alicyclic alkyl" refers to a alkyl that contains only alicyclic hydrocarbon structure as a ring structure and does not contain an aromatic ring structure. Among them, it is not necessary to be composed only of alicyclic hydrocarbon structure, and it also includes those having a chain structure in part. The term "aromatic hydrocarbon group" refers to a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it is not necessary to be composed of only an aromatic ring structure, and a part of the aromatic ring structure may contain a chain structure or an alicyclic hydrocarbon structure.

When the liquid crystal alignment agent disclosed herein is prepared as a polymer composition for forming a photoalignment film, ^A1 in the formula (1) is preferably a monovalent group having a photoalignment group. The photoalignment group possessed by ^A1 is preferably a functional group that imparts anisotropy to the film by photoisomerization reaction, photodimerization reaction, photo Fries rearrangement reaction, or photodecomposition reaction under light irradiation.

In the case where ^A1 has a photo-alignment group, specific examples of the photo-alignment group include: an azobenzene-containing group including azobenzene or its derivatives as a basic skeleton, a cinnamic acid structure-containing group including cinnamic acid or its derivatives (cinnamic acid structure) as a basic skeleton, a chalcone-containing group including chalcone or its derivatives as a basic skeleton, a benzophenone-containing group including benzophenone or its derivatives as a basic skeleton, a coumarin-containing group including coumarin or its derivatives as a basic skeleton, a phenylbenzoate-containing group including phenylbenzoate or its derivatives as a basic skeleton, a cyclobutane-containing structure including cyclobutane or its derivatives as a basic skeleton, etc. Among these, the photo-alignment group is preferably a cinnamic acid structure-containing group in terms of high photosensitivity. Specifically, a group containing a cinnamic acid structure represented by the following formula (3) as a basic skeleton is particularly preferred. (In formula (3), R ¹¹ and R ¹² are independently a hydrogen atom, a fluorine atom, a cyano group, an alkyl group having 1 to 3 carbon atoms, or a fluoroalkyl group having 1 to 3 carbon atoms; R ¹³ is an alkyl group having 1 to 10 carbon atoms which may have a fluorine atom or a cyano group, an alkoxy group having 1 to 10 carbon atoms which may have a fluorine atom or a cyano group, a fluorine atom, or a cyano group; a is an integer of 0 to 4; when a is 2 or more, a plurality of R ¹³ are the same group or different groups; "*" represents a bonding bond)

In the structure represented by the formula (3), it is preferred that both R ¹¹ and R ¹² are hydrogen atoms, or one of them is a hydrogen atom and the other (preferably R ¹² ) is an alkyl group having 1 to 3 carbon atoms, in order to further improve the photoreactivity. R ¹³ is preferably an alkyl group having 1 to 5 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. a is preferably 0 to 2, more preferably 0 or 1.

In terms of being able to more appropriately control the pre-tilt angle of the obtained liquid crystal element, it is preferred that one of the two bonding bonds "*" in the formula (3) is bonded to a base having at least one benzene ring and cyclohexane ring in total, and it is more preferred that it is bonded to a base having at least two benzene rings and cyclohexane rings in total. Specifically, it is preferred that one of the two bonding bonds "*" in the formula (3) is a bonding bond to a base represented by the following formula (4). [Chemistry 4] (In formula (4), ^X1 , when bonded to the phenyl group in formula (3), is a single bond, an alkanediyl group having 1 to 3 carbon atoms, an oxygen atom, a sulfur atom, -CH=CH-, -NH-, -COO-, or -OCO-; when bonded to the carbonyl group in formula (3), is a single bond, an alkanediyl group having 1 to 3 carbon atoms, an oxygen atom, a sulfur atom, or -NH-; ^R14 and ^R15 are each independently a substituted or unsubstituted phenylene group, or a substituted or unsubstituted cyclohexylene group; R ^{R 16} is phenyl or cyclohexyl, or a monovalent group in which at least one hydrogen atom of the phenyl or cyclohexyl group is replaced by an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a substituted alkyl group having 1 to 10 carbon atoms in which at least one hydrogen atom is replaced by a fluorine atom or a cyano group, a substituted alkoxy group having 1 to 10 carbon atoms in which at least one hydrogen atom is replaced by a fluorine atom or a cyano group, a fluorine atom, or a cyano group; r is an integer of 0 to 3; when r is 2 or more, multiple R ¹⁵ are the same group or different groups; "*" represents a bond)

In the formula (4), the substituent bonded to the ring of the phenylene group and the cyclohexylene group is preferably an alkyl group having 1 to 3 carbon atoms, a fluorine atom or a cyano group. r is preferably 0 or 1. ^{R 16} is preferably a monovalent group in which at least one hydrogen atom of the phenyl group or the cyclohexyl group is substituted by a substituted or unsubstituted alkyl group or alkoxy group. In this case, the substituted or unsubstituted alkyl group or alkoxy group preferably has 2 or more carbon atoms, and more preferably has 3 or more carbon atoms.

From the viewpoint of improving the solubility of the polymer (A) in the solvent, ^A2 in the formula (1) and the formula (2) is preferably a hydroxyl group or a group " ^-OR17 " (wherein ^R17 is a monovalent hydrocarbon group having 1 to 10 carbon atoms), more preferably a hydroxyl group or an alkoxy group having 1 to 3 carbon atoms, and still more preferably a hydroxyl group or a methoxy group.

The monomer (R1) has a saturated heterocyclic ring containing -CO-N( ^A1 )-CO-, or a structure formed by ring-opening the saturated heterocyclic ring. In the formula (1) and the formula (2), n1+n2 is preferably 1 or more, and more preferably an integer of 1 to 6. In terms of obtaining a polymer having better solubility in a solvent, the monomer (R1) is preferably a compound represented by the formula (2), that is, a ring-opened form of the compound represented by the formula (1).

In the formula (1) and the formula (2), ^R1 and ^R2 represent that one of ^R1 and ^R2 is a monovalent group having a polymerizable group, and the other is a hydrogen atom or a monovalent organic group, or ^R1 and ^R2 are bonded to each other to form a ring structure (hereinafter also referred to as "ring structure X") together with the nitrogen atom to which ^R1 and ^R2 are bonded. The ring structure X has a polymerizable carbon-carbon unsaturated bond in the ring. The polymerizable group possessed by one of ^R1 and ^R2 and the polymerizable carbon-carbon unsaturated bond possessed by the ring structure X can be selected according to the main skeleton of the polymer (A). The polymer (A) may be a polymer produced by addition polymerization of monomers (hereinafter, also referred to as "addition polymer (A1)") or a polymer produced by condensation polymerization of monomers (hereinafter, also referred to as "condensation polymer (A2)").

(Addition polymer) The addition polymer (A1) may be a polymer obtained using a monomer having a group containing a carbon-carbon unsaturated bond as a polymerizable group, and its main skeleton is not particularly limited. The addition polymer (A1) can be obtained by addition polymerization of a monomer (R1) having a group containing a carbon-carbon unsaturated bond as a polymerizable group.

In the monomer (R1) used in the synthesis of the addition polymer (A1), when one of ^R1 and ^R2 is a monovalent group having a polymerizable group and the other is a hydrogen atom or a monovalent organic group, the monovalent group having a polymerizable group is preferably a group represented by the following formula (5). (In formula (5), Y ¹ is vinylphenyl, (meth)acryloxy, (meth)acrylamide, vinyl, vinyloxy, or maleimide; R ¹⁸ is a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms; X ² is a single bond, -CO-, * ¹ -O-CO-, or * ¹ -NH-CO- (wherein "* ¹ " represents a bond with R ¹⁸ ); "*" represents a bond with a nitrogen atom in formula (1) or (2))

In the monomer (R1) used in the synthesis of the addition polymer (A1), when ^R1 and ^R2 are bonded to each other to form a ring structure X, the ring structure X may be a monocyclic ring or a polycyclic ring (including a condensed ring and a bridged ring). The ring structure X preferably has 4 to 15 carbon atoms, more preferably 4 to 12 carbon atoms.

Preferred specific examples of the ring structure X include: monocyclic structures represented by the following formulae (x1-1) to (x1-4); polycyclic structures represented by the following formulae (x2-1) to (x2-8); and the like. (Where “*” represents a bond)

As specific examples of the monomer (R1) used in the synthesis of the addition polymer (A1), the compound represented by the formula (1) may include compounds represented by the following formulas (r1-1) to (r1-29), etc.; the compound represented by the formula (2) may include compounds (ring-opened forms) formed by ring-opening of the succinimide ring or glutarimide ring possessed by the compounds represented by the following formulas (r1-1) to (r1-29), etc. [Chemistry 7] [Chemistry 8] [Chemistry 9] [Chemistry 10] [Chemistry 11] [Chemistry 12] [Chemistry 13] (In formula (R1-1) to formula (R1-29), ^R20 is an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a substituted alkyl group having 1 to 10 carbon atoms in which at least one hydrogen atom is substituted by a fluorine atom or a cyano group, a substituted alkoxy group having 1 to 10 carbon atoms in which at least one hydrogen atom is substituted by a fluorine atom or a cyano group, a fluorine atom, or a cyano group; ^R21 is a hydrogen atom or a methyl group; ^R22 is an alkanediyl group having 1 to 10 carbon atoms)

The monomer (R1) can be synthesized according to conventional methods of organic chemistry. As an example, an aminoalkane dioic acid (e.g., 2-aminobutyric acid, 2-aminoglutaric acid, etc.) can be used as a raw material to synthesize a compound represented by the following formula (R-1), and then the compound represented by the following formula (R-1) is reacted with a compound represented by the following formula (R-2) to obtain a compound represented by the above formula (2). In addition, if necessary, the compound represented by the above formula (2) is ring-closed in the presence of a catalyst (e.g., zinc chloride, a silylating agent, etc.), thereby obtaining a compound represented by the above formula (1). The method for synthesizing the monomer (R1) is not limited to the above method. [Chemistry 14] (In formula (R-1) and formula (R-2), R ¹ , R ² , A ¹ , n1 and n2 have the same meanings as in formula (1) and formula (2))

From the viewpoint of making the pre-tilt angle characteristics (initial pre-tilt angle and post-bake margin) better, the content ratio of the structural unit U1 in the addition polymer (A1) is preferably 1 mol% or more, more preferably 2 mol% or more, and further preferably 5 mol% or more relative to all the monomer units possessed by the addition polymer (A1). In addition, the content ratio of the structural unit U1 relative to all the monomer units possessed by the addition polymer (A1) can be arbitrarily set within the range of 100 mol% or less. When other structural units different from the structural unit U1 are introduced, the content ratio of the structural unit U1 relative to all the monomer units possessed by the addition polymer (A1) is preferably 90 mol% or less, more preferably 80 mol% or less, further preferably 60 mol% or less, and particularly preferably 50 mol% or less. The structural unit U1 contained in the addition polymer (A1) may be one type or two or more types.

(Other structural units) The addition polymer (A1) may have only the structural unit U1, or may have the structural unit U1 and a structural unit derived from a monomer different from the monomer (R1) (hereinafter also referred to as "other structural units"). The addition polymer (A1) preferably has a structural unit derived from at least one selected from the group consisting of a compound containing a maleimide structure, a (meth)acrylic acid compound, a compound containing a styrene structure, a compound containing a maleic anhydride structure, and a cyclic olefin compound as the other structural unit.

The maleimide structure-containing compound is not particularly limited as long as it is a compound having a maleimide ring or a ring-opened form thereof. Specific examples of the maleimide structure-containing compound include a compound represented by the following formula (z-1) and a compound represented by the following formula (z-2). [Chemistry 15] (In formula (z-1) and formula (z-2), R ³¹ , R ³² , R ³⁴ and R ³⁵ are each independently a hydrogen atom or a methyl group; R ³³ and R ³⁶ are each independently a monovalent organic group; "*" represents a bonding bond)

In the above formula (z-1) and formula (z-2), the monovalent organic group of R ³³ and R ³⁶ includes a monovalent alkyl group having 1 to 40 carbon atoms, a group in which at least one methylene group of the alkyl group is substituted with -O-, -CO-, -COO-, -NR ²⁶ - or -CONR ²⁶ - (wherein R ²⁶ is a hydrogen atom or a monovalent alkyl group) (hereinafter also referred to as "group β"), and a group in which at least one hydrogen atom of the monovalent alkyl group or group β having 1 to 40 carbon atoms is substituted with a substituent such as a fluorine atom, a cyano group, a carboxyl group, an epoxide group, a hydroxyl group or a cyclic carbonate group. The monovalent organic group of R ³³ and R ³⁶ is preferably a group having a photoalignment group, a group having a vertical alignment group, or a group having a crosslinking group. When the monovalent organic group of R ³³ and R ³⁶ is a group having a photo-alignment group, the group having a photo-alignment group is preferably a group having a cinnamic acid structure represented by the above formula (3).

Here, the so-called "vertical alignment group" is a functional group that imparts the function of inducing the desired pre-tilt angle of the liquid crystal molecules to the coating formed using the liquid crystal alignment agent. The vertical alignment group exhibits the property of vertically aligning the liquid crystal molecules independently of light irradiation. Specific examples of the vertical alignment group include: an alkyl group having 4 to 40 carbon atoms, an alkoxy group having 4 to 40 carbon atoms, a fluoroalkyl group having 4 to 40 carbon atoms, a group having 12 to 50 carbon atoms in a structure having two or more rings (preferably 1,4-phenylene and 1,4-cyclohexylene) bonded via a single bond or a divalent linking group (-O-, -COO-, etc.), a group having 17 to 51 carbon atoms having a steroid skeleton, etc.

Examples of compounds containing a maleimide structure include N-methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, 4-carboxyphenylmaleimide, 2-methylphenylmaleimide, 4-hydroxyphenylmaleimide, N-dodecylmaleimide, N-cholestanyloxycarbonylphenylmaleimide, and compounds obtained by ring-opening the maleimide ring of these compounds (ring-opened forms).

The (meth)acrylic acid compound only needs to have a (meth)acrylic acid group, and the rest of the structure is not particularly limited. Specific examples of the (meth)acrylic acid compound include: (meth)acrylic acid, α-ethylacrylic acid, maleic acid, fumaric acid, itaconic acid, alkyl (meth)acrylates, cycloalkyl (meth)acrylates, benzyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, glycidyl (meth)acrylate, α-ethylacrylate glycidyl, α-n-propylacrylate glycidyl, α-n-butylacrylate glycidyl, (meth)acrylate, ) 3,4-epoxybutyl acrylate, α-ethyl acrylate, 3,4-epoxybutyl (meth)acrylate, 6,7-epoxyheptyl (meth)acrylate, α-ethyl acrylate, 6,7-epoxyheptyl acrylate, 4-hydroxybutyl glycidyl acrylate, (3-ethyloxycyclobutane-3-yl)methyl (meth)acrylate, propylene carbonate (meth)acrylate, 3-hydroxy-1-adamantyl (meth)acrylate, and the like.

Examples of compounds containing a styrene structure include styrene, methylstyrene, 4-vinyl-1-glycidyloxymethylbenzene, 3-vinyl-1-glycidyloxymethylbenzene, 3-vinylbenzoic acid, and 4-vinylbenzoic acid. Examples of compounds containing a maleic anhydride structure include maleic anhydride and citric anhydride. Examples of cyclic olefin compounds include cyclobutene, cyclopentyne, cyclohexene, and bicyclo[2.2.1]hept-2-ene.

Examples of other structural units possessed by the addition polymer (A1) include, in addition to the above, vinyl-containing compounds such as ethylene, vinyl alcohol, (meth)allyl alcohol, and 3-methyl-3-butene-1-ol; and covalent diene compounds such as 1,3-butadiene and 2-methyl-1,3-butadiene. The addition polymer (A1) may have only one other structural unit or may have two or more other structural units.

When ^A1 in the structural unit U1 is a monovalent group having a photo-alignment group, from the viewpoint of suppressing the pre-tilt angle manifested by the liquid crystal alignment film from becoming too high, the addition polymer (A1) is preferably a structural unit having the structural unit U1 and a monomer derived from at least one of the group consisting of a maleimide structure-containing compound, a (meth)acrylic compound, a styrene structure-containing compound, a maleic anhydride structure-containing compound, and a cyclic olefin compound and not having a photo-alignment group (hereinafter also referred to as "structural unit U2").

When ^A1 is a monovalent group having a photo-alignment group, the content ratio of the structural unit U2 in the addition polymer (A1) is preferably 50 mol% or more, more preferably 55 mol% or more, and further preferably 60 mol% or more relative to all monomer units possessed by the addition polymer (A1). In addition, the content ratio of the structural unit U2 is preferably 99 mol% or less, more preferably 97 mol% or less, and further preferably 95 mol% or less relative to all monomer units possessed by the addition polymer (A1). Furthermore, the structural unit U2 possessed by the addition polymer (A1) may be only one kind or may be two or more kinds.

(Cyclic ether structure and cyclic carbonate structure) In order to further reduce the deviation of the pre-tilt angle (post-bake margin) relative to the difference in heating temperature (post-bake temperature) during film formation, the addition polymer (A1) preferably has a structural unit (hereinafter, also referred to as "structural unit U3") derived from the following monomer, wherein the monomer has at least one selected from the group consisting of a cyclic ether structure and a cyclic carbonate structure. Examples of the cyclic ether structure include: an oxycyclobutane ring structure, an oxycyclopropane ring structure, etc. Examples of the cyclic carbonate structure include: an ethyl carbonate structure, a propylene carbonate structure, etc. Among these, the structural unit U3 is preferably a structural unit derived from a monomer having a cyclic ether structure, and more preferably a structural unit derived from a monomer having an oxycyclobutane ring structure or an oxycyclopropane ring structure.

The structural unit U3 is preferably a structural unit derived from at least one selected from the group consisting of a (meth)acrylic acid compound, a compound containing a maleimide structure, and a compound containing a styrene structure. Among these, in terms of high freedom of choice of monomers, a structural unit derived from at least one selected from the group consisting of a (meth)acrylic acid compound and a compound containing a styrene structure is more preferred.

When the addition polymer (A1) has a structural unit U3, the ratio of the structural unit U3 is preferably 5 mol% or more, more preferably 10 mol% or more, and further preferably 20 mol% or more relative to all monomer units of the addition polymer (A1). In addition, the content ratio of the structural unit U3 is preferably 90 mol% or less, more preferably 85 mol% or less, and further preferably 70 mol% or less relative to all monomer units of the addition polymer (A1). Furthermore, the structural unit U3 of the addition polymer (A1) may be only one type, or may be two or more types.

(Reactive functional group) From the perspective of further improving the effect of improving the post-bake margin, the addition polymer (A1) preferably has a functional group that reacts with at least one of the cyclic ether structure and the cyclic carbonate structure (hereinafter, also referred to as a "reactive functional group"). Examples of reactive functional groups include: carboxyl group, hydroxyl group, isocyanate group and amine group, and groups of these groups protected by protective groups. From the perspective of good storage stability and high reactivity based on heating, the reactive functional group is preferably at least one selected from the group consisting of a carboxyl group and a protected carboxyl group (hereinafter, also referred to as a "protected carboxyl group").

The protected carboxyl group is not particularly limited as long as it is heat-dissociated to generate a carboxyl group. Preferred specific examples of the protected carboxyl group include the structure represented by the following formula (6), the acetal ester structure of carboxylic acid, the ketal ester structure of carboxylic acid, and the like. [Chemistry 16] (In formula (6), R ⁴¹ , R ⁴² and R ⁴³ are each independently an alkyl group having 1 to 10 carbon atoms or a monovalent alicyclic alkyl group having 3 to 20 carbon atoms, or represent a divalent alicyclic alkyl group having 4 to 20 carbon atoms or a cyclic ether group formed by R ⁴¹ and R ⁴² bonding to each other and the carbon atoms to which R ⁴¹ and R ⁴² bond, and R ⁴³ is an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms; "*" represents a bonding bond)

The monomer having a reactive functional group is preferably at least one selected from the group consisting of a (meth)acrylic acid compound, a compound containing a maleimide structure, and a compound containing a styrene structure. Among these, in terms of high freedom of selection of the monomer, at least one selected from the group consisting of a (meth)acrylic acid compound and a compound containing a styrene structure is more preferred.

When the addition polymer (A1) has a structural unit derived from a monomer having a reactive functional group (hereinafter, also referred to as a "structural unit U4"), the content ratio of the structural unit U4 is preferably 2 mol% or more, more preferably 5 mol% or more, and further preferably 10 mol% or more relative to all the monomer units possessed by the addition polymer (A1). In addition, the content ratio of the structural unit U4 is preferably 70 mol% or less, more preferably 60 mol% or less, and further preferably 50 mol% or less relative to all the monomer units possessed by the addition polymer (A1). Furthermore, the structural unit U4 possessed by the addition polymer (A1) may be only one type, or may be two or more types.

(Photosensitizing structure) The polymer (A) may also have a partial structure (hereinafter, also referred to as a "photosensitizing structure") that can exhibit a photosensitizing function by irradiation with light. In the case where the polymer (A) has a photosensitizing structure, a liquid crystal alignment film with a smaller deviation in the pre-tilt angle caused by the difference in heating temperature during film formation can be obtained, which is suitable in this respect. Here, the so-called "photosensitizing function" refers to the function of rapidly generating intersystem crossing and jumping to a triplet excited state after becoming a singlet excited state by irradiation with light. If it collides with other molecules in the triplet state, it changes the other party to an excited state and restores itself to the basic state.

The photosensitizing structure of the polymer (A) is not particularly limited, and examples thereof include: acetophenone structure, benzophenone structure, anthraquinone structure, biphenyl structure, terphenyl structure, carbazole structure, nitroaryl structure (nitrobenzene structure, 1,3-dinitrobenzene structure, etc.), naphthalene structure, fluorene structure, anthracene structure, 9,10-dihydroanthracene structure, acridine structure, indole structure, 1,4-dioxocyclohexa-2,5-diene structure, etc. The polymer (A) preferably has a photosensitizing structure in the side chain.

When the addition polymer (A1) is a polymer having a photosensitizing structure, the method for obtaining the addition polymer (A1) is not particularly limited, and preferably, a monomer (R1) and a monomer having a photosensitizing structure are used for polymerization. As specific examples of the monomer having a photosensitizing structure, compounds represented by the following formula (9) can be cited. Y ² -L ¹ -Y ³ …(9) (In formula (9), Y ² is a vinylphenyl group, a (meth)acryloxy group, a (meth)acrylamide group, a vinyl group, a vinyloxy group, or a maleimide group, L ¹ is a single bond or a divalent linking group, and Y ³ is a group having a photosensitizing structure)

In the formula (9), ^Y2 is preferably a (meth)acryloyloxy group or a (meth)acryloylamino group, and more preferably a (meth)acryloyloxy group, from the perspective of increasing the degree of freedom in selecting the monomer. The divalent linking group of ^L1 is preferably a divalent hydrocarbon group having 1 to 10 carbon atoms or a group having -O- between the carbon-carbon bonds of the hydrocarbon group. ^Y3 is preferably an acetophenone structure, a benzophenone structure, an anthraquinone structure, a biphenyl structure, a terphenyl structure, a carbazole structure, a nitroaryl structure, a naphthalene structure, a fluorene structure, an anthracene structure, a 9,10-dihydroanthracene structure, an acridine structure, an indole structure, or a 1,4-dioxocyclohexa-2,5-diene structure.

When the addition polymer (A1) has a structural unit derived from a monomer having a photosensitizing structure (hereinafter, also referred to as a "structural unit U5"), the ratio of the structural unit U5 is preferably 1 mol% or more, more preferably 2 mol% or more, and further preferably 3 mol% or more relative to all the monomer units possessed by the addition polymer (A1). In addition, the content ratio of the structural unit U5 is preferably 50 mol% or less, more preferably 40 mol% or less, and further preferably 30 mol% or less relative to all the monomer units possessed by the addition polymer (A1). Furthermore, the structural unit U5 possessed by the addition polymer (A1) may be only one type, or may be two or more types.

The addition polymer (A1) can be obtained by polymerizing the monomer (R1) and other monomers used as needed in an organic solvent, preferably in the presence of a polymerization initiator. Examples of the polymerization initiator include azo compounds such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), and nickel catalysts. The polymerization initiator is preferably used in an amount of 0.01 to 30 parts by mass relative to 100 parts by mass of all monomers used in the reaction. Examples of the organic solvent include alcohols, ethers, ketones, amides, esters, hydrocarbons, and the like.

In the polymerization reaction, the reaction temperature is preferably 30°C to 120°C, and the reaction time is preferably 1 hour to 36 hours. The amount of the organic solvent used (a) is preferably an amount such that the total amount (b) of the monomers used in the reaction is 0.1% by mass to 60% by mass relative to the total amount (a+b) of the reaction solution. The reaction solution in which the polymer is dissolved can be used for the preparation of a liquid crystal alignment agent after separating the addition polymer (A1) contained in the reaction solution using a known separation method, such as a method of drying a precipitate obtained by injecting the reaction solution into a large amount of a poor solvent under reduced pressure, a method of diluting the reaction solution under reduced pressure using an evaporator, etc.

The weight average molecular weight (Mw) of the addition polymer (A1) measured by gel permeation chromatography (GPC) in terms of polystyrene is preferably 1,000 to 300,000, more preferably 2,000 to 100,000. The molecular weight distribution (Mw/Mn) represented by the ratio of Mw to the number average molecular weight (Mn) in terms of polystyrene measured by GPC is preferably 7 or less, more preferably 5 or less. The addition polymer (A1) used in the preparation of the liquid crystal alignment agent may be only one kind or a combination of two or more kinds.

(Condensation product) The condensation product (A2) may be a polymer obtained by using a monomer having a condensable group as a polymerizable group, and its main skeleton is not particularly limited. In terms of high improvement in coating uniformity and pre-tilt angle characteristics of the obtained liquid crystal alignment film, the condensation product (A2) is preferably a polyorganosiloxane having a structural unit U1 (hereinafter, also referred to as "polyorganosiloxane (A)"). The polyorganosiloxane (A) can be obtained by a hydrolysis-condensation reaction using a hydrolyzable silane compound represented by the formula (1) or the formula (2) (hereinafter, also referred to as "specific silane compound") as the monomer (R1).

Regarding the specific silane compound, one of ^R1 and R2 in the formula (1) and the formula ( ² ) is a monovalent group having a polymerizable group, and the other is a hydrogen atom or a monovalent organic group. The polymerizable group is preferably an alkoxysilyl group. The specific silane compound is preferably at least one selected from the group consisting of a compound represented by the following formula (7) and a compound represented by the following formula (8). [Chemical 17] (In formula (7) and formula (8), ^R23 is a divalent hydrocarbon group having 1 to 20 carbon atoms, ^R24 and ^R25 are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms, ^R27 is a hydrogen atom or a monovalent organic group; k is an integer of 1 to 3; ^A1 , n1 and n2 have the same meanings as in formula (1) and formula (2))

Specific examples of the specific silane compound include compounds represented by the following formulae (s1-1) to (s1-10). [Chemistry 19] (In the above formulas (s1-1) to (s1-10), R ²³ , R ²⁴ , R ²⁵ , R ²⁷ and k have the same meanings as in the above formula (7); R ²⁰ is an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a substituted alkyl group having 1 to 10 carbon atoms in which at least one hydrogen atom is substituted by a fluorine atom or a cyano group, a substituted alkoxy group having 1 to 10 carbon atoms in which at least one hydrogen atom is substituted by a fluorine atom or a cyano group, a fluorine atom, or a cyano group)

In the synthesis of the polyorganosiloxane (A), only the specific silane compound may be used as the hydrolyzable silane compound, or a hydrolyzable silane compound other than the specific silane compound (hereinafter also referred to as "other silane compound") may be used in combination.

Other silane compounds are not particularly limited as long as they can be condensed with the specific silane compound. Examples thereof include tetraalkoxysilane compounds or alkylalkoxysilane compounds such as tetramethoxysilane, methyltriethoxysilane, and dimethyldiethoxysilane; cycloalkylalkoxysilane compounds such as cyclohexyltrimethoxysilane and cyclohexylmethyldimethoxysilane; phenyltrimethoxysilane; alkoxysilane compounds such as aryl alkoxysilane, phenyltriethoxysilane, etc.; nitrogen-sulfur alkoxysilane compounds such as 3-butylpropyltriethoxysilane, butylmethyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-(3-cyclohexylamino)propyltrimethoxysilane; 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, etc. Silane compounds containing epoxy groups such as 3-glycidyloxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane; 3-(methyl)acryloyloxypropyltrimethoxysilane, 3-(methyl)acryloyloxypropylmethyldimethoxysilane, 3-(methyl)acryloyloxypropyltrimethoxysilane, ) alkoxysilane compounds containing unsaturated bonds such as acryloxypropylmethyldiethoxysilane, vinyltriethoxysilane, and p-phenylenetrimethoxysilane; silane compounds containing anhydride groups such as trimethoxysilylpropylsuccinic anhydride; silane compounds containing isocyanate groups such as 3-isocyanatepropyltrimethoxysilane and 3-isocyanatepropyltriethoxysilane. As other silane compounds, one of these may be used alone or two or more may be used in combination. In addition, "(meth)acryl" includes "acryl" and "methacryl".

From the viewpoint of making the pre-tilt angle characteristics (initial pre-tilt angle and post-bake margin) better, the content ratio of the structural unit U1 in the polyorganosiloxane (A) is preferably 1 mol% or more, more preferably 2 mol% or more, and further preferably 5 mol% or more relative to all monomer units possessed by the polyorganosiloxane (A). In addition, the content ratio of the structural unit U1 relative to all monomer units possessed by the polyorganosiloxane (A) is preferably 90 mol% or less, more preferably 80 mol% or less, and further preferably 60 mol% or less. Furthermore, the structural unit U1 possessed by the polyorganosiloxane (A) may be one type or two or more types.

The hydrolysis-condensation reaction is carried out in the following manner: preferably, one or more of the hydrolyzable silane compounds described above are reacted with water in the presence of a suitable catalyst and an organic solvent. During the reaction, the water is preferably used in an amount of 1 to 30 mol relative to 1 mol of the silane compound (total amount). Examples of the catalyst used include acids, alkaline metal compounds, organic bases, titanium compounds, zirconium compounds, etc. The amount of the catalyst used varies depending on the type of catalyst, reaction conditions such as temperature, etc., and should be appropriately set. For example, it is preferably 0.01 to 3 times the total amount of the silane compound. Examples of the organic solvent include hydrocarbons, ketones, esters, ethers, and alcohols, among which water-insoluble or poorly water-soluble organic solvents are preferred. The organic solvent is preferably used in an amount of 10 to 10,000 parts by mass relative to 100 parts by mass of the total silane compound used in the reaction.

The hydrolysis-condensation reaction is preferably carried out by heating, for example, in an oil bath. In this case, the heating temperature is preferably set to 130° C. or less, and the heating time is preferably set to 0.5 to 12 hours. After the reaction is completed, the organic solvent layer separated from the reaction solution is dried using a desiccant as needed, and the solvent is removed to obtain the target polyorganosiloxane. Furthermore, the synthesis method of polyorganosiloxane is not limited to the hydrolysis-condensation reaction, and can also be carried out by, for example, the following method: reacting a hydrolyzable silane compound in the presence of oxalic acid and alcohol.

The polyorganosiloxane (A) preferably has a polystyrene-equivalent weight average molecular weight (Mw) measured by GPC in the range of 100 to 50,000, more preferably 200 to 10,000.

In the liquid crystal alignment agent disclosed herein, from the viewpoint of sufficiently improving the coating property on the substrate and making the pre-tilt angle characteristics (initial pre-tilt angle, post-baking margin) excellent, the content ratio of polymer (A) relative to all polymers contained in the liquid crystal alignment agent is preferably 0.1 mass % or more, more preferably 0.5 mass % or more, and further preferably 1 mass % or more. In addition, the content ratio of polymer (A) can be appropriately set within the range of 100 mass % or less relative to all polymers contained in the liquid crystal alignment agent. According to the polymer (A), even if the amount used is reduced, the effect of improving the coating uniformity and pre-tilt angle characteristics can be obtained. From the perspective of achieving cost reduction of the liquid crystal alignment agent and sufficient improvement in reliability, the content ratio of polymer (A) relative to the total amount of polymers contained in the liquid crystal alignment agent is preferably 90 mass % or less, more preferably 70 mass % or less, and even more preferably 50 mass % or less.

<Other components> The liquid crystal alignment agent disclosed herein may contain other components besides the polymer (A) as needed.

(Other polymers) The liquid crystal alignment agent disclosed herein may contain polymer (A) and polymers that do not have structural units derived from monomer (R1) (hereinafter, also referred to as "other polymers") as polymer components. The other polymers are not particularly limited, and at least one polymer selected from the group consisting of polyamic acid, polyamic acid ester, polyimide and polyurea (hereinafter, also referred to as "polymer (B)") can be preferably used. By using polymer (B) together with polymer (A), the liquid crystal alignment and electrical properties of the obtained liquid crystal element can be guaranteed, which is preferred in this regard. Polymer (B) is more preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester and polyimide.

When the polymer (B) is polyamic acid, the polyamic acid can be obtained by reacting tetracarboxylic dianhydride with a diamine compound. In this case, as tetracarboxylic dianhydride and diamine compound, previously known compounds used in the synthesis of polyamic acid can be used. Polyamic acid ester can be obtained, for example, by the following methods: a method of reacting the obtained polyamic acid with an esterifying agent (for example, methanol or ethanol, N,N-dimethylformamide diethyl acetal, etc.); a method of reacting a tetracarboxylic acid diester with a diamine compound in the presence of a suitable dehydration catalyst; a method of reacting a tetracarboxylic acid diester dihalide with a diamine in the presence of a suitable base. Polyimide can be obtained, for example, by dehydrating and ring-closing the obtained polyamic acid and performing imidization. The imidization rate of the polyimide is preferably 20% to 90%, more preferably 30% to 80%.

The polymer (B) preferably has a polystyrene-equivalent weight average molecular weight (Mw) of 1,000 to 500,000, more preferably 2,000 to 300,000, and a molecular weight distribution (Mw/Mn) of 7 or less, more preferably 5 or less, as measured by GPC.

When the liquid crystal alignment agent contains polymer (A) and polymer (B) as polymer components, from the viewpoint of fully obtaining the improvement effect of the pre-tilt angle characteristics brought about by the formulation of polymer (A) and making the liquid crystal alignment property good, the content ratio of polymer (B) is preferably set to 100 parts by mass or more relative to 100 parts by mass of polymer (A) in the liquid crystal alignment agent. The content ratio of polymer (B) is more preferably 100 parts by mass to 2000 parts by mass, and further preferably 200 parts by mass to 1500 parts by mass. In addition, as polymer (B), one kind may be used alone, or two or more kinds may be used in combination.

(Photosensitizer) The liquid crystal alignment agent disclosed herein preferably contains a compound having a photosensitizing structure (hereinafter, also referred to as a "photosensitizer"). The photosensitizer may be a polymer (A) having a structural unit derived from a monomer (R1) and a photosensitizing structure, or may be another polymer, or may be an additive component separately formulated from the polymer component (hereinafter, also referred to as an "additive (S)"). In addition, the liquid crystal alignment agent may also contain both a polymer (A) and an additive (S). The additive (S) is preferably a compound having a photosensitizing structure and a molecular weight of 1000 or less.

Specific examples of the additive (S) include: compounds containing an acetophenone structure, such as acetophenone benzyl ketone, 2,2-dimethoxy-2-phenylacetophenone, and 3-methylacetophenone; benzophenone, 4-diethylamino-2-hydroxybenzophenone, 2-hydroxybenzophenone, 4-methylbenzophenone, 3-(4-benzoyl-phenoxy)propyl, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone (Michler's ketone); ketone) and other compounds containing benzophenone structure; 3,5-dinitrobenzene, 4-methyl-3,5-dinitrobenzene, 3-(3,5-dinitrophenoxy)propyl, 2-methyl-3,5-dinitrobenzene and other compounds containing nitroaryl structure; naphthalene, anthracene, biphenyl, terphenyl, 2,3-benzofluorene, pyrene, perylene, fluorene, anthraquinone and other hydrocarbons; 9,10-dioxo-9,10-dihydroanthracene, 3-(9,10-dioxo-9,10-dihydroanthracen-2-yl)propyl, Anthracene derivatives such as 2-oxo-9,10-dihydroanthracene; amino-containing compounds such as triphenylamine and carbazole; sulfur-containing compounds such as thioanthrone, diethylthioanthrone, 2-isopropylthioanthrone, 2-chlorothioanthrone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-propane-1-one; phosphorus-containing compounds such as 2,4,6-trimethylbenzyldiphenylphosphine oxide and bis-(2,6-dimethoxybenzyl)-2,4,4-trimethylpentylphosphine oxide. In addition, as the additive (S), one kind may be used alone, or two or more kinds may be used in combination.

When the additive (S) is used as a photosensitizer, from the viewpoint of further improving the effect of reducing the post-bake margin, the content of the additive (S) in the liquid crystal alignment agent is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, relative to 100 parts by mass of the total polymer component in the liquid crystal alignment agent. In addition, from the viewpoint of suppressing the performance degradation caused by excessive addition, the content of the additive (S) is preferably 30 parts by mass or less, and more preferably 20 parts by mass or less, relative to 100 parts by mass of the total polymer component.

(Solvent) The liquid crystal alignment agent disclosed herein is prepared in the form of a solution composition, wherein the solution composition is preferably prepared by dissolving a polymer component and an optional component as needed in an organic solvent. Examples of the organic solvent used include: aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons, etc. The solvent component may be one of these or a mixed solvent of two or more.

As a solvent component of the liquid crystal alignment agent, it is preferable to use at least one solvent selected from the group consisting of a compound represented by the following formula (D-1), a compound represented by the following formula (D-2), and a compound represented by the following formula (D-3) and having a boiling point of 180°C or less at 1 atmosphere (hereinafter also referred to as a "specific solvent"). By using a specific solvent as at least a part of the solvent component, a liquid crystal element having excellent liquid crystal alignment and electrical properties can be obtained even when heating is performed at a low temperature (e.g., below 200°C) during film formation, which is preferable in this respect. [Chemistry 20] (In formula (D-1), ^R1 is an alkyl group having 1 to 4 carbon atoms or _CH3CO- , ^R2 is an alkanediyl group having 1 to 4 carbon atoms or -( _CH2CH2O )n- _CH2CH2- (wherein _n is an integer of 1 to 4), _and ^R3 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms) [Chemistry 21] (In formula (D-2), ^R4 is an alkanediyl group having 1 to 3 carbon atoms) [Chemical 22] (In formula (D-3), ^R5 and ^R6 are independently an alkyl group having 4 to 8 carbon atoms)

As specific examples of the specific solvent, the compound represented by the formula (D-1) may include propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, diethylene glycol methyl ethyl ether, 3-methoxy-1-butanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol-n-butyl ether (butyl solvent), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, etc.; The compound represented by the formula (D-2) may include cyclobutanone, cyclopentanone, cyclohexanone; The compound represented by the formula (D-3) may include diisobutyl ketone, etc. Furthermore, as the specific solvent, one kind may be used alone, or two or more kinds may be used in combination.

The solvent component of the liquid crystal alignment agent may only contain a specific solvent, or may be a mixed solvent of other solvents other than the specific solvent and the specific solvent. As other solvents, for example, highly polar solvents such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,2-dimethyl-2-imidazolidinone, γ-butyrolactone, γ-butyrolactamide, N,N-dimethylformamide, and N,N-dimethylacetamide can be listed; in addition, highly polar solvents such as 4-hydroxy-4-methyl-2-pentanone, butyl lactate, and 4-hydroxy-4-methyl-2-pentanone can be listed. Ester, butyl acetate, methyl methoxy propionate, ethyl ethoxy propionate, 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, isoamyl propionate, isoamyl isobutyrate, diisoamyl ether, ethyl carbonate, propyl carbonate, cyclohexane, octanol, tetrahydrofuran, etc. These may be used alone or in combination of two or more.

Regarding the solvent component contained in the liquid crystal alignment agent, the content ratio of the specific solvent relative to the total amount of the solvent contained in the liquid crystal alignment agent is preferably 20 mass % or more, more preferably 40 mass % or more, and further preferably 50 mass % or more.

As other components contained in the liquid crystal alignment agent, in addition to the above components, for example, there can be listed: functional silane compounds, multifunctional (meth)acrylates, antioxidants, metal chelate compounds, hardening accelerators, surfactants, fillers, dispersants, photosensitizers, etc. The mixing ratio of other components can be appropriately selected according to each compound within the range that does not impair the effects of the present disclosure.

The solid component concentration in the liquid crystal alignment agent (the ratio of the total mass of the components other than the solvent of the liquid crystal alignment agent to the total mass of the liquid crystal alignment agent) can be appropriately selected in consideration of viscosity, volatility, etc., and is preferably in the range of 1 mass % to 10 mass %. When the solid component concentration is 1 mass % or more, a coating with sufficient film thickness can be obtained, and a good liquid crystal alignment film can be easily obtained. On the other hand, when the solid component concentration is 10 mass % or less, the film thickness of the coating will not be too large, and the viscosity of the liquid crystal alignment agent can be made moderate, which can suppress the reduction of coating properties, and is suitable in this respect.

《Liquid crystal alignment film and liquid crystal element》 The liquid crystal alignment film disclosed herein is formed by a liquid crystal alignment agent prepared as described above. In addition, the liquid crystal element disclosed herein 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. For example, it can be applied to various modes such as twisted nematic (TN), super twisted nematic (STN), vertical alignment (VA) (including vertical alignment-multi-domain vertical alignment (VA-MVA), vertical alignment-patterned vertical alignment (VA-PVA), in-plane switching (IPS), fringe field switching (FFS), optically compensated bend (OCB), polymer stabilized alignment (PSA), etc. 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 coated on a substrate, and preferably the coated surface is heated to form a coating film on the substrate. As the substrate, for example, a transparent substrate comprising the following materials can be used: glass such as float glass and sodium glass; plastics such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, poly(aliphatic cycloolefin) and the like. As a transparent conductive film disposed on one side of the substrate, a NESA film (registered trademark of PPG, USA) comprising tin oxide (SnO ₂ ), an indium tin oxide (ITO) film comprising indium oxide-tin oxide (In ₂ O ₃ -SnO ₂ ), and the like can be used. In the case of manufacturing TN type, STN type or VA type liquid crystal elements, two substrates provided with patterned transparent conductive films are used. On the other hand, in the case of manufacturing IPS type or FFS type liquid crystal elements, a substrate provided with electrodes patterned into a comb shape and an opposing substrate without electrodes are used. The liquid crystal alignment agent is preferably applied to the substrate on the electrode formation surface by lithography, flexographic printing, rotary coating, roll coating or inkjet printing.

After applying the liquid crystal alignment agent, it is preferred to perform preheating (pre-baking) for the purpose of preventing the applied liquid crystal alignment agent from dripping. The pre-baking temperature is preferably 30°C to 200°C, and the pre-baking time is preferably 0.25 minutes to 10 minutes. Thereafter, a calcination (post-baking) step is performed for the purpose of completely removing the solvent. The calcination temperature (post-baking temperature) at this time is preferably 80°C to 250°C, and more preferably 80°C to 200°C. The post-baking time is preferably 5 minutes to 200 minutes. In particular, when the prepared liquid crystal alignment agent is used, the solubility in a low-boiling point solvent such as a specific solvent is good, and even when the post-baking temperature is set to, for example, 200°C or less, preferably 180°C or less, and more preferably 160°C or less, the deviation of the pre-tilt angle caused by the difference in the post-baking temperature can be further reduced, which is preferable in this respect. The film thickness of the film formed in this way is preferably 0.001 μm to 1 μm.

<Step 2: Alignment treatment> In the case of manufacturing TN type, STN type, IPS type or FFS type liquid crystal elements, a treatment (alignment treatment) is performed to impart liquid crystal alignment ability to the coating formed in the step 1. In this way, the coating is endowed with the alignment ability of liquid crystal molecules to form a liquid crystal alignment film. In the case of manufacturing a vertical alignment type liquid crystal element, the coating formed in the step 1 can be directly used as a liquid crystal alignment film, but in order to further improve the liquid crystal alignment ability, the coating can also be subjected to an alignment treatment. As the alignment treatment, it is preferable to use a light alignment treatment in which the coating formed on the substrate is irradiated with light to impart liquid crystal alignment ability to the coating.

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

As the light source used, for example, there can be listed: low-pressure mercury lamp, high-pressure mercury lamp, deuterium lamp, metal halide lamp, argon resonance lamp, xenon lamp, excimer laser, etc. The radiation exposure is preferably 400 J/m ² to 50,000 J/m ² , more preferably 1,000 J/m ² to 20,000 J/m ^2. After the light irradiation for imparting alignment ability, the substrate surface can be cleaned using water, an organic solvent (for example, methanol, isopropyl alcohol, 1-methoxy-2-propanol acetate, butyl solvent, ethyl lactate, etc.) or a mixture thereof, or the substrate can be heated.

<Step 3: Construction of liquid crystal cell> Prepare two substrates with liquid crystal alignment films formed in the above manner, and arrange liquid crystal between the two substrates arranged opposite to each other, thereby manufacturing a liquid crystal cell. When manufacturing a liquid crystal cell, for example, the following methods can be listed: arrange the two substrates opposite to each other with a gap in between so that the liquid crystal alignment films face each other, use a sealant to bond the periphery of the two substrates, inject liquid crystal into the cell gap surrounded by the substrate surface and the sealant and seal the injection hole, and use a liquid crystal drop (One Drop Fill, ODF) method. As a sealant, for example, an epoxy resin containing a hardener and aluminum oxide balls as a spacer can be used. As a liquid crystal, nematic liquid crystal and lamellar liquid crystal can be listed, among which nematic liquid crystal is preferred. In the PSA mode, after a liquid crystal cell is constructed, the liquid crystal cell is subjected to light irradiation treatment while a voltage is applied between conductive films on a pair of substrates.

Then, a polarizing plate is attached to the outer surface of the liquid crystal unit as needed to make a liquid crystal element. Examples of polarizing plates include: a polarizing plate formed by sandwiching a polarizing film called "H film" with a cellulose acetate protective film, or a polarizing plate containing the H film itself. The "H film" is formed by stretching and aligning polyvinyl alcohol while absorbing iodine.

The liquid crystal element disclosed herein can be effectively applied to various purposes, for example, it can be applied to various display devices such as clocks, portable game consoles, word processors, notebook personal computers, car navigation systems, video cameras, personal digital assistants (PDAs), digital cameras, mobile phones, smart phones, various monitors, liquid crystal televisions, information displays, or dimming films, phase difference films, etc. [Example]

The present invention will be described in more detail below with reference to embodiments, but the present invention is not limited to these embodiments.

In the following examples and comparative examples, the weight average molecular weight of the polymer was measured by the following method. [Weight average molecular weight of polymer] The weight average molecular weight is a polystyrene conversion value measured by gel permeation chromatography under the following conditions. Column: TSKgelGRCXLII manufactured by Tosoh Co., Ltd. Solvent: Tetrahydrofuran Temperature: 40°C Pressure: 68 kgf/cm ²

The structural formula of the compound used in this example is shown below. In addition, for convenience, the "compound represented by formula (X)" is sometimes referred to as "compound (X)". [Chemical 23] [Chemistry 24] [Chemistry 25] [Chemistry 26]

<Synthesis of Compounds> [Synthesis Example 1-1: Synthesis of Compound (MA-2)] Compound (MA-2) was synthesized according to the following scheme. [Chemical 27]

Add 13.3 g of aspartic acid and 200 ml of tetrahydrofuran (THF) to an eggplant-shaped flask and dissolve them. Add 9.81 g of maleic acid, stir for 1 hour, and distill off the solvent using an evaporator. Add 300 ml of toluene, 24.2 g of hexamethyldisilazane, and 27.3 g of zinc chloride to the obtained solid, and react at 80°C for 4 hours. After the reaction, the reaction solution was purified by liquid separation twice using hydrochloric acid (1N) and by liquid separation twice using water. Then, the organic layer was concentrated using an evaporator. The obtained solid was crystallized using THF/ethanol/water to obtain 14.2 g of intermediate 1. The intermediate 1 was dissolved in THF, and 28.6 g of amine cinnamate represented by the formula (CA) (hereinafter referred to as "Compound CA") was added and reacted at 50° C. for 1 hour. After the reaction, the solvent was distilled off to obtain 42.5 g of Compound (MA-2).

[Synthesis Example 1-2: Synthesis of Compound (MA-1)] Compound (MA-1) was synthesized according to the following scheme.

To 17.9 g of compound (MA-2), 300 ml of toluene, 7.26 g of hexamethyldisilazane, and 8.18 g of zinc chloride were added and reacted at 80°C for 4 hours. After the reaction, the reaction solution was purified by liquid separation twice using hydrochloric acid (1N) and by liquid separation twice using water. Then, the organic layer was concentrated by an evaporator. The obtained solid was crystallized by THF/ethanol/water to obtain 7.34 g of compound (MA-1).

[Synthesis Example 1-3: Synthesis of Compound (MA-3)] Synthesis was performed in the same manner as Compound (MA-2) except that the starting material was 3-aminoglutaric acid.

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

While nitrogen is flowing in a three-necked eggplant-shaped flask, 200 ml of dehydrated THF is added to 13.3 g of aspartic acid to dissolve it. 15.5 g of "Karenz MOI" (manufactured by Showa Denko) is added thereto, and the mixture is reacted at 50°C for 8 hours, and the solvent is distilled off. Next, 300 ml of toluene, 24.2 g of hexamethyldisilazane, 27.3 g of zinc chloride, and 1 g of dibutylhydroxytoluene are added, and the mixture is reacted at 50°C for 8 hours. After the reaction, the reaction solution is purified by liquid separation twice using hydrochloric acid (1N) and by liquid separation twice using water. Next, the organic layer is concentrated using an evaporator. The obtained solid was crystallized using THF/ethanol/water to obtain 10.0 g of intermediate 2. Then, intermediate 2 was dissolved in THF, and 14.5 g of compound CA was added and reacted at 50°C for 1 hour. After the reaction, the solvent was distilled off to obtain 22.9 g of compound (MA-4).

[Synthesis Example 1-5: Synthesis of Compound (MA-5)] Synthesis was performed in the same manner as Compound (MA-4) except that the starting material was 5-norbornene-2,3-dicarboxylic anhydride.

[Synthesis Example 1-6: Synthesis of Compound (MA-6)] Compound (MA-6) was synthesized according to the following scheme.

Add 13.3 g of aspartic acid, 10 ml of pyridine, and 150 ml of dehydrated THF to an eggplant-shaped flask, dissolve them, and cool them in an ice bath. Slowly drop 4-vinylbenzoic acid chloride dissolved in 50 ml of dehydrated THF, and then react for 15 hours. After the reaction, add 100 ml of ethyl acetate, and perform liquid separation and purification twice with hydrochloric acid (1N) and water. Then, concentrate the organic layer with an evaporator. Crystallize the obtained solid with THF/ethanol/water to obtain 20.3 g of intermediate 3. Intermediate 3 was dissolved in THF, and 32.4 g of compound CA was added, and reacted at 50°C for 1 hour. After the reaction, the solvent was distilled off to obtain 51.6 g of a compound (MA-6).

[Synthesis Example 1-7: Synthesis of Compound (MA-7)] Compound (MA-7) was synthesized according to the following scheme.

To 3.46 g of N-allyl aspartic acid, 30 ml of toluene, 4.84 g of hexamethyldisilazane, and 5.45 g of zinc chloride were added, and the mixture was reacted at 80°C for 4 hours. After the reaction, the reaction solution was purified by liquid separation twice using hydrochloric acid (1N) and by liquid separation twice using water. Then, the organic layer was concentrated by an evaporator. The obtained solid was crystallized using THF/ethanol/water to obtain 1.68 g of intermediate 4. The obtained intermediate 4 was dissolved in THF, and 4.27 g of compound CA was added, and the mixture was reacted at 50°C for 1 hour. After the reaction, the solvent was distilled off to obtain 5.45 g of intermediate 5. Furthermore, the intermediate 5 and 300 μl of a 0.01 M hexachloroplatinum (IV) acid hexahydrate solution were dissolved in 20 ml of THF under a nitrogen atmosphere. 1.26 g of trimethoxysilane was slowly added dropwise thereto, and then the mixture was reacted at 70° C. for 3 days. After the reaction, the solvent was distilled off, and crystallization was performed using THF/ethanol to obtain 3.71 g of compound (MA-7).

<Synthesis of polymer> [Synthesis Example 2-1] In a 100 mL two-necked flask under nitrogen, 1.71 g (3.00 mmol) of compound (MA-1) as a polymerization monomer, 0.70 g (7.00 mmol) of compound (MB-4), 0.10 g (0.41 mmol) of 2,2'-azobis(2,4-dimethylvaleronitrile) as a free radical polymerization initiator, 0.10 g (0.44 mmol) of 2,4-diphenyl-4-methyl-1-pentene as a chain transfer agent, and 15 ml of N-methyl-2-pyrrolidone (NMP) as a solvent were added, and polymerization was carried out at 70°C for 6 hours. After reprecipitation in methanol, the precipitate was filtered and vacuum dried at room temperature for 8 hours to obtain the target polymer (P-1). The weight average molecular weight Mw measured by GPC in terms of polystyrene was 30,000, and the molecular weight distribution Mw/Mn was 2.8.

[Synthesis Example 2-2 to Synthesis Example 2-5, Synthesis Example 2-7 and Synthesis Example 2-8] Polymers (P-2) to (P-5), polymers (P-7) and polymers (P-8) were synthesized by the same method as Synthesis Example 2-1 except that the types and amounts of the monomers used were changed as described in Table 1 below. In Table 1, the units of the values of the monomer composition are "molar parts".

[Table 1] Synthesis Example No. Single body (R1) Other single bodies Polymer Name MA-1 MA-2 MA-3 MA-4 MA-5 MA-6 MB-1 MB-2 MB-3 MB-4 MB-5 MB-6 MB-7 MB-8 2-1 30 70 P-1 2-2 30 20 50 P-2 2-3 5 50 45 P-3 2-4 30 15 35 20 P-4 2-5 7 3 10 40 40 P-5 2-7 20 40 15 20 5 P-7 2-8 10 25 35 10 20 P-8

[Synthesis Example 2-6] In a reaction container including a stirrer, a thermometer, a dropping funnel, and a reflux cooling tube, 40 mol parts of compound (MA-7), 20 mol parts of compound (MS-1), 40 mol parts of compound (MS-2), 50 g of methyl isobutyl ketone, and 5 g of triethylamine were placed and mixed at room temperature. Then, 35 g of deionized water was added dropwise using a dropping funnel over 30 minutes, and the mixture was mixed under reflux and reacted at 80°C for 6 hours. After the reaction was completed, the organic layer was taken out and washed with a 0.2 mass% ammonium nitrate aqueous solution until the washed water became neutral, and then the solvent and water were distilled off under reduced pressure to obtain a polymer (P-6) as a polyorganosiloxane in the form of a viscous transparent liquid. The weight average molecular weight (Mw) of the obtained polymer (P-6) was 11,000.

[Synthesis Example 2-9] 100 mol parts of 1,2,3,4-cyclobutanetetracarboxylic dianhydride and 100 mol parts of 2,2'-dimethyl-4,4'-diaminobiphenyl were dissolved in N-methyl-2-pyrrolidone (NMP), and the mixture was reacted at 40°C for 3 hours to obtain a solution containing 10% by mass of a polymer (P-9) as a polyamide. [Synthesis Example 2-10] 100 mol parts of 2,3,5-tricarboxycyclopentylacetic dianhydride, 20 mol parts of 3,5-diaminobenzoic acid, and 80 mol parts of 2,2'-dimethyl-4,4'-diaminobiphenyl were dissolved in NMP, and the mixture was reacted at 40°C for 3 hours to obtain a solution containing 10% by mass of a polymer (P-10) as a polyamide.

[Synthesis Example 2-11] According to the procedure of Preparation Example 2 described in Korean Patent Publication No. 2015-138548, a maleimide resin having a chalcone side chain was synthesized (hereinafter referred to as "polymer (P-11)"). [Synthesis Example 2-12] According to the procedure of Example 1 described in Japanese Patent Publication No. 2962473, a maleimide resin having a cinnamoyl group on the side chain was synthesized (hereinafter referred to as "polymer (P-12)"). [Synthesis Example 2-13] According to the procedure of Preparation Example 1 described in Japanese Patent Publication No. 2015-152743, a styrene resin having a cinnamoyl group on the side chain was synthesized (hereinafter referred to as "polymer (P-13)"). [Synthesis Example 2-14] According to the procedure of Example 27 described in Japanese Patent No. 5803915, 1,2,3,4-cyclobutanetetracarboxylic dianhydride and (E)-3,5-diaminobenzyl 3-(2-(4-butoxyphenyl)-1,3-dioxoisoindolin-5-yl)acrylate were used to synthesize polyamide (hereinafter referred to as "polymer (P-14)").

<Manufacturing and evaluation of liquid crystal display device> [Example 1] (1) Preparation of liquid crystal alignment agent In a container containing 100 parts by mass of the polymer (P-1) obtained in Synthesis Example 2-1, cyclopentanone (CPN) and butyl cellulose (BC) as solvents were added to prepare a solution having a solvent composition of CPN/BC = 70/30 (mass ratio) and a solid content of 3.5 mass %. The solution was filtered using a filter with a pore size of 1 μm to prepare a liquid crystal alignment agent (AL-1).

(2) Production of a vertical light type liquid crystal display element The liquid crystal alignment agent (AL-1) prepared in (1) was applied to the transparent electrode surface of a glass substrate with a transparent electrode including an ITO film by a rotator, and pre-baked for 1 minute using a hot plate at 80°C to form a coating with a thickness of 0.08 μm. Then, using a Hg-Xe lamp and a Glan-Taylor prism, the coating surface was irradiated with 200 J/m ² of polarized ultraviolet light including a bright line of 313 nm at room temperature from a direction inclined by 40° from the substrate normal. Then, in an oven whose interior was replaced with nitrogen, it was heated at 160°C for 40 minutes (main calcination) to produce a liquid crystal alignment film. The same operation was repeated to produce a pair (two) of substrates with liquid crystal alignment films. An epoxy resin adhesive containing aluminum oxide balls with a diameter of 3.5 μm was applied to the periphery of the surface of one of the two substrates with the liquid crystal alignment film formed thereon by screen printing. The liquid crystal alignment film surfaces of the pair of substrates were then made to face each other, and the pair of substrates were pressed together in such a way that the projection direction of the optical axis of the ultraviolet light irradiated to each substrate on the substrate surface became antiparallel, and the adhesive was thermally cured at 150°C for 1 hour. Subsequently, the gap between the substrates was filled with nematic liquid crystal (MLC-6608 manufactured by Merck) from the liquid crystal injection port, and the liquid crystal injection port was sealed with an epoxy adhesive to obtain a liquid crystal unit. Furthermore, in order to remove the flow alignment when the liquid crystal is injected, the liquid crystal unit is heated to 150°C and then slowly cooled to room temperature. Secondly, polarizing plates are attached to the outer sides of the substrate in the liquid crystal unit in such a way that the polarization directions of the polarizing plates are orthogonal to each other and form a 45° angle with the projection direction of the optical axis of the ultraviolet light irradiated when the liquid crystal alignment film is formed on the substrate surface.

(3) Evaluation of pre-tilt angle Regarding the liquid crystal display element manufactured in (2), according to the method described in the non-patent document (T. J. Scheffer et al., "Journal of Applied Physics (J. Appl. Phys.)", vol. 19, p2013 (1980)), the value of the tilt angle of the liquid crystal molecules relative to the substrate surface was measured by the crystal rotation method using He-Ne laser light, and the value was set as the pre-tilt angle. At this time, when the pre-tilt angle is less than 89.0°, it is set as "good (○)", and when it is greater than 89.0°, it is set as "bad (×)". As a result, in this embodiment, the pre-tilt angle is evaluated as "good (○)".

(4) Evaluation of coating uniformity The liquid crystal alignment agent (AL-1) prepared in (1) was coated on a glass substrate using a spinner, pre-baked on a hot plate at 80°C for 1 minute, and then heated (post-baked) in a 200°C oven replaced with nitrogen for 1 hour to form a coating with an average film thickness of 0.1 μm. The surface of the obtained coating was observed using an atomic force microscope (AFM) and the center average roughness (Ra) was measured to evaluate the uniformity of the coating surface. The coating uniformity was evaluated as "good (○)" when Ra was 5 nm or less, "acceptable (△)" when Ra was greater than 5 nm and less than 10 nm, and "poor (×)" when Ra was greater than 10 nm. As a result, the coating uniformity was evaluated as "acceptable (△)" in this example.

(5) Evaluation of the deviation characteristics of the pre-tilt angle relative to the difference in post-baking temperature (post-baking margin) According to the method of (2), a liquid crystal alignment film was prepared at different post-baking temperatures (150°C and 200°C), and the pre-tilt angles of the two obtained liquid crystal display elements were measured. The deviation characteristics of the pre-tilt angle relative to the difference in post-baking temperature were evaluated by taking the difference Δθ (=｜θ200-θ150｜) between the measured value θ200 of the pre-tilt angle of the liquid crystal display element with the post-baking temperature set to 200°C and the measured value θ150 of the pre-tilt angle of the liquid crystal display element with the post-baking temperature set to 150°C. It can be said that the smaller Δθ is, the smaller the deviation of the pre-tilt angle relative to the difference in post-baking temperature is, and the better it is. The pre-tilt angle is measured according to the method described in the non-patent literature (T. J. Scheffer et al., "Journal of Applied Physics (Vol. 19, p. 2013) (1980)), by using the crystal rotation method using He-Ne laser light to measure the value of the tilt angle of the liquid crystal molecules relative to the substrate surface, and this value is set as the pre-tilt angle [°]. When evaluating, a Δθ of 0.1° or less was rated as "excellent (◎)", a Δθ of more than 0.1° and less than 0.2° was rated as "good (○)", a Δθ of more than 0.2° and less than 0.5° was rated as "acceptable (△)", and a Δθ of more than 0.5° was rated as "poor (×)". As a result, the evaluation of this embodiment was "acceptable (△)".

[Example 2 to Example 11, Comparative Example 1 to Comparative Example 4] The liquid crystal alignment agent formulation was changed as shown in Table 2 below. The liquid crystal alignment agents were prepared in the same manner as in Example 1 except for this aspect. In addition, a photovertical liquid crystal display device was manufactured in the same manner as in Example 1 using each prepared liquid crystal alignment agent, and various evaluations were performed in the same manner as in Example 1. The results are shown in Table 2 below. In addition, in Examples 3 to 11 and Comparative Examples 1 to 4, two polymers were formulated. In Example 11, an additive (photosensitizer) was formulated in the liquid crystal alignment agent.

[Table 2] Polymer composition Additives Solvent Reviews 1 2 Composition (mass ratio) Coating uniformity Pre-tilt angle Baking allowance Embodiment 1 P-1 (100) CPN/BC=70/30 △ ○ △ Embodiment 2 P-2 (100) CPN/BC=70/30 ○ ○ △ Embodiment 3 P-2 (20) P-9 (100) MB/BC=70/30 ○ ○ △ Embodiment 4 P-3 (1) P-9 (100) CPN/BC=70/30 ○ ○ ○ Embodiment 5 P-4 (15) P-9 (100) NMP/BC=50/50 ○ ○ ○ Embodiment 6 P-5 (40) P-9 (100) NMP/BC=50/50 ○ ○ ○ Embodiment 7 P-6 (5) P-9 (100) EDM/BC=70/30 ○ ○ ○ Embodiment 8 P-7 (3) P-10 (100) NMP/BC=50/50 ○ ○ ◎ Embodiment 9 P-8 (8) P-10 (100) PGME/BC=50/50 ○ ○ ◎ Embodiment 10 P-3 (14) P-10 (100) Add-1 (5) NMP/BC=50/50 ○ ○ ◎ Comparison Example 1 P-11 (10) P-9 (100) NMP/BC=50/50 × × (High tilt angle) × Comparison Example 2 P-12 (15) P-9 (100) NMP/BC=50/50 × × (High tilt angle) ○ Comparison Example 3 P-13 (8) P-9 (100) NMP/BC=50/50 × × (High tilt angle) ○ Comparison Example 4 P-14 (12) P-9 (100) NMP/BC=50/50 ○ × (High tilt angle) ×

In Table 2, the values in parentheses in the columns of polymer components and additives indicate the blending ratio of each compound (unit: mass parts). The abbreviations of solvents are as follows. PGME: Propylene glycol monomethyl ether EDM: Diethylene glycol methyl ethyl ether CPN: Cyclopentanone MB: 3-methoxy-1-butanol NMP: N-methyl-2-pyrrolidone BC: γ-butyrolactone

As shown in Table 2, in Examples 1 to 10 in which the liquid crystal alignment agent containing polymer (A) is prepared, the pre-tilt angle is less than 89 degrees, and the tilt angle of the liquid crystal molecules relative to the vertical direction can be sufficiently increased compared with Comparative Examples 1 to 4 not containing polymer (A). In addition, in Examples 1 to 11, the deviation of the pre-tilt angle caused by the difference in post-baking temperature is small. In particular, in Examples 8 and 9 in which a polymer having a photosensitizing structure is formulated, and in Example 10 in which an additive having a photosensitizing structure is formulated, the evaluation of the post-baking margin is "excellent", which is particularly excellent. Furthermore, the coating uniformity of the liquid crystal alignment agents of Examples 1 to 10 is also good. In addition, it is known that by using a ring-opening body as a monomer (R1), the coating uniformity can be improved. Based on these results, it is known that by using a polymer (A), a liquid crystal alignment film with good coating uniformity and excellent pre-tilt angle characteristics can be formed.

without

Claims (11)

A liquid crystal alignment agent comprises a polymer (A), wherein the polymer (A) has a structural unit derived from at least one monomer selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2),

(In formula (1) and formula (2), ^R1 and ^R2 represent that one of ^R1 and ^R2 is a monovalent group having a polymerizable group and the other is a hydrogen atom or a monovalent organic group, or ^R1 and ^R2 are combined with each other to form a ring structure together with the nitrogen atom to which ^R1 and ^R2 are bonded; wherein the ring structure has a polymerizable carbon-carbon unsaturated bond; ^A1 is a monovalent organic group, ^A2 is a hydroxyl group or a monovalent organic group; n1 and n2 are each independently an integer satisfying 0≦n1+n2≦8). The liquid crystal alignment agent as described in claim 1, wherein ^A1 is a monovalent group having a photo-alignment group. The liquid crystal alignment agent as described in claim 1 or claim 2 further contains a polymer (B), wherein the polymer (B) is at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide and polyurea. The liquid crystal alignment agent as described in claim 1 or claim 2, wherein the polymer (A) has a structural unit derived from the following monomer, and the monomer has at least one selected from the group consisting of a cyclic ether structure and a cyclic carbonate structure. The liquid crystal alignment agent as described in claim 1 or claim 2, wherein the polymer (A) has a structural unit derived from the following monomer, and the monomer has at least one selected from the group consisting of a carboxyl group and a protective carboxyl group. The liquid crystal alignment agent as described in claim 1 or claim 2 contains a compound having the following partial structure as the polymer (A) or additive component, and the partial structure can show a photosensitizing function by showing a sensitizing effect by light irradiation. A liquid crystal alignment film, which is formed using a liquid crystal alignment agent as described in any one of claim 1 to claim 6. A liquid crystal element, comprising a liquid crystal alignment film as described in claim 7. A polymer having a structural unit derived from at least one monomer selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2),

(In formula (1) and formula (2), ^R1 and ^R2 represent that one of ^R1 and ^R2 is a monovalent group having a polymerizable group and the other is a hydrogen atom or a monovalent organic group, or ^R1 and ^R2 are combined with each other to form a ring structure together with the nitrogen atom to which ^R1 and ^R2 are bonded; wherein the ring structure has a polymerizable carbon-carbon unsaturated bond; ^A1 is a monovalent group having a photoalignment group, and ^A2 is a hydroxyl group or a monovalent organic group; n1 and n2 are each independently an integer satisfying 0≦n1+n2≦8). A compound represented by the following formula (1):

(In formula (1), ^R1 and ^R2 represent that one of ^R1 and ^R2 is a monovalent group having a polymerizable group and the other is a hydrogen atom or a monovalent organic group, or ^R1 and ^R2 are combined with each other to form a ring structure together with the nitrogen atom to which ^R1 and ^R2 are bonded; wherein the ring structure has a polymerizable carbon-carbon unsaturated bond; ^A1 is a monovalent group having a photoalignment group, and ^A2 is a hydroxyl group or a monovalent organic group; n1 and n2 are each independently an integer satisfying 0≦n1+n2≦8). A compound represented by the following formula (2):

(In formula (2), ^R1 and ^R2 represent that one of ^R1 and ^R2 is a monovalent group having a polymerizable group and the other is a hydrogen atom or a monovalent organic group, or ^R1 and ^R2 are combined with each other to form a ring structure together with the nitrogen atom to which ^R1 and ^R2 are bonded; wherein the ring structure has a polymerizable carbon-carbon unsaturated bond; ^A1 is a monovalent group having a photoalignment group, and ^A2 is a hydroxyl group or a monovalent organic group; n1 and n2 are each independently an integer satisfying 0≦n1+n2≦8).