JP7409388B2 - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal element - Google Patents

Description

Cross-reference of related applications

This application is based on Japanese Patent Application No. 2019-187165 filed on October 10, 2019, and the contents thereof are incorporated herein.

The present disclosure 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. A liquid crystal aligning film is generally formed by applying a liquid crystal aligning agent in which a polymer component is dissolved in an organic solvent to a substrate, and preferably heating the liquid crystal aligning agent. Polyamic acids and soluble polyimides have long been used as polymer components for liquid crystal aligning agents because of their excellent mechanical strength, liquid crystal orientation, and affinity with liquid crystals.

As a method for imparting liquid crystal alignment ability to a polymer thin film formed using a liquid crystal aligning agent, a photo alignment method has been proposed as a technique to replace the rubbing method. The photoalignment method is a method in which a radiation-sensitive organic thin film formed on a substrate is irradiated with polarized or non-polarized radiation to impart anisotropy to the film, thereby controlling the alignment of liquid crystals.

As a liquid crystal aligning agent for forming a liquid crystal aligning film by a photoalignment method, a liquid crystal aligning agent containing a polymer having a main skeleton different from polyamic acid and soluble polyimide has been provided (for example, Patent Document 1 and Patent Document 1). (See Reference 2). Patent Document 1 discloses a photo-alignable composition containing a reaction product of a polymer having a maleic anhydride structure and a primary amine compound having a photo-alignable group. Patent Document 2 describes a first polymer having a main chain of poly(maleimide) or poly(maleimide-styrene) and having a photosensitive group introduced into the side chain, and a second polymer having a long-chain alkyl group in the side chain. A photoalignable composition comprising a molecule is disclosed.

Korean Publication Patent No. 2015-138548 Patent No. 2962473

The angle between the long axis of the liquid crystal molecule and the substrate surface (pretilt angle) greatly affects the display characteristics of the liquid crystal element. The present inventors controlled the alignment of liquid crystals so that the long axes of liquid crystal molecules were tilted at an appropriate angle with respect to the vertical direction (for example, so that the pretilt angle was 89 degrees or less in a vertically aligned liquid crystal element). By doing this, we attempted to obtain a liquid crystal element with higher definition than ever before. However, when a 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 with respect to the vertical direction, and the pretilt angle is lower than the desired angle. I found it to be expensive.

Moreover, in recent years, it is sometimes required to use a low-boiling point solvent as a solvent component of a liquid crystal aligning agent for the purpose of enabling low-temperature firing in the heating step during film formation. When the polymer component is not uniformly dissolved in the solvent, coating unevenness occurs in the liquid crystal alignment film formed on the substrate, and there is a possibility that a flat film cannot be formed (poor coating uniformity). In this case, there is concern that the product yield will decrease and display performance such as liquid crystal alignment and electrical properties will be affected.

Furthermore, when a liquid crystal alignment film is formed by low-temperature firing, the pretilt angle of the liquid crystal alignment film deviates from the pretilt angle of the liquid crystal alignment film obtained by conventional high-temperature firing (for example, heat treatment at a temperature of about 230 to 250°C). Sometimes. Such variations in pretilt angle due to differences in heating temperature during film formation (hereinafter also referred to as "post-bake margin") affect the display quality of the liquid crystal element, so it is desirable that it be as small as possible.

The present disclosure has been made in view of the above circumstances, and its main purpose is to provide a liquid crystal alignment agent that can form a liquid crystal alignment film that has good coating uniformity and excellent pretilt angle characteristics. .

In order to solve the above problems, the present inventors used a polymer having a specific structure as a polymer component of a liquid crystal aligning agent, and found that the above problems could be solved. Specifically, the present disclosure provides the following means.

（式（１）及び式（２）中、Ｒ^１及びＲ^２は、Ｒ^１及びＲ^２のうち一方が重合性基を有する１価の基であり、他方が水素原子若しくは１価の有機基であるか、又は、Ｒ^１及びＲ^２が互いに合わせられＲ^１及びＲ^２が結合する窒素原子と共に構成される環構造を表す。ただし、前記環構造は、重合性炭素－炭素不飽和結合を有する。Ａ^１は１価の有機基であり、Ａ^２は水酸基又は１価の有機基である。ｎ１及びｎ２は、それぞれ独立に、０≦ｎ１＋ｎ２≦８を満たす整数である。）
［２］上記［１］の液晶配向剤を用いて形成された液晶配向膜。
［３］上記［２］の液晶配向膜を具備する液晶素子。
［４］上記式（１）で表される化合物及び上記式（２）で表される化合物よりなる群から選択される少なくとも一種の単量体に由来する構造単位を有する重合体。
［５］上記式（１）で表される化合物。
［６］上記式（２）で表される化合物。[1] A polymer (A) 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). Contains a liquid crystal alignment agent.

(In formula (1) and formula (2), one of R ^{1 and} R ² is a monovalent group having a polymerizable group, and ^the other is a hydrogen atom or a monovalent organic group. or represents a ring structure formed by combining R ¹ and R ² together with the nitrogen atom to which R ¹ and R ² are bonded.However, the ring structure does not contain a polymerizable carbon-carbon unsaturated bond. ( ^A1 is a monovalent organic 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.)
[2] A liquid crystal aligning film formed using the liquid crystal aligning agent of [1] above.
[3] A liquid crystal element comprising the liquid crystal alignment film of [2] above.
[4] A polymer having a structural unit derived from at least one monomer selected from the group consisting of the compound represented by the above formula (1) and the compound represented by the above formula (2).
[5] A compound represented by the above formula (1).
[6] A compound represented by the above formula (2).

By containing the polymer (A) in a liquid crystal aligning agent, a liquid crystal aligning agent with good coating uniformity can be obtained. In addition, by forming a liquid crystal alignment film using the above-mentioned liquid crystal alignment agent, the tilt angle from the vertical direction of the liquid crystal molecules can be made sufficiently large, and the pretilt angle can also vary due to differences in heating temperature during film formation. can be made smaller. That is, according to the above liquid crystal aligning agent, a liquid crystal aligning film having excellent pretilt angle characteristics can be formed.

（式（１）及び式（２）中、Ｒ^１及びＲ^２は、Ｒ^１及びＲ^２のうち一方が水素原子又は１価の有機基であり、他方が重合性基を有する１価の基であるか、又は、Ｒ^１及びＲ^２が互いに合わせられＲ^１及びＲ^２が結合する窒素原子と共に構成される環構造を表す。ただし、前記環構造は、重合性炭素－炭素不飽和結合を有する。Ａ^１は１価の有機基であり、Ａ^２は水酸基又は１価の有機基である。ｎ１及びｎ２は、それぞれ独立に、０≦ｎ１＋ｎ２≦８を満たす整数である。）Hereinafter, matters related to the present disclosure will be explained in detail.
≪Liquid crystal alignment agent≫
The liquid crystal aligning agent of the present disclosure has a structural unit 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). Contains a polymer (A) having U1.

(In formula (1) and formula (2), R ^{1 and R 2 are} a hydrogen atom or a monovalent organic group, and the other is a monovalent group having a polymerizable group. or represents a ring structure formed by combining R ¹ and R ² together with the nitrogen atom to which R ¹ and R ² are bonded.However, the ring structure does not contain a polymerizable carbon-carbon unsaturated bond. ( ^A1 is a monovalent organic 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.)

<Polymer (A)>
(Structural unit U1)
In the above formulas (1) and (2), the monovalent organic groups of A ¹ and A ² include a monovalent hydrocarbon group having 1 to 40 carbon atoms, and at least one methylene group of the hydrocarbon group. is ^a group ( ^hereinafter referred to ^as ), 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 with a fluorine atom or a cyano group.

Here, in this specification, the term "hydrocarbon group" includes a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. The term "chain hydrocarbon group" refers to a straight chain hydrocarbon group and a branched hydrocarbon group that do not contain a cyclic structure in the main chain and are composed only of a chain structure. However, it may be saturated or unsaturated. "Alicyclic hydrocarbon group" means a hydrocarbon group containing only an alicyclic hydrocarbon structure as a ring structure and not containing an aromatic ring structure. However, it does not have to be composed only of an alicyclic hydrocarbon structure, and includes a structure having a chain structure as a part thereof. "Aromatic hydrocarbon group" means a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it is not necessary to consist only of an aromatic ring structure, and a part thereof may include a chain structure or an alicyclic hydrocarbon structure.

When the liquid crystal aligning agent of the present disclosure is used as a polymer composition for forming a photoalignment film, A ¹ in the above formula (1) is preferably a monovalent group having a photoalignment group. . The photo-orientable group that A ¹ has is preferably a functional group that imparts anisotropy to the film through photoisomerization reaction, photodimerization reaction, photo-Fries rearrangement reaction, or photodecomposition reaction upon irradiation with light.

（式（３）中、Ｒ^１１及びＲ^１２は、それぞれ独立して水素原子、フッ素原子、シアノ基、炭素数１～３のアルキル基、又は炭素数１～３のフルオロアルキル基であり、Ｒ^１３は、フッ素原子若しくはシアノ基を有していてもよい炭素数１～１０のアルキル基、フッ素原子若しくはシアノ基を有していてもよい炭素数１～１０のアルコキシ基、フッ素原子、又はシアノ基である。ａは０～４の整数である。ａが２以上の場合、複数のＲ^１３は同一の基又は異なる基である。「＊」は結合手であることを表す。）When A ¹ has a photo-alignable group, specific examples of the photo-alignable group include an azobenzene-containing group containing azobenzene or a derivative thereof as a basic skeleton, and a group containing cinnamic acid or a derivative thereof (cinnamic acid structure) as a basic skeleton. Cinnamic acid structure-containing group, chalcone-containing group containing chalcone or its derivative as a basic skeleton, benzophenone-containing group containing benzophenone or its derivative as basic skeleton, coumarin-containing group containing coumarin or its derivative as basic skeleton, phenylbenzoate or its derivative Examples include a phenylbenzoate-containing group containing as a basic skeleton, a cyclobutane-containing structure containing cyclobutane or a derivative thereof as a basic skeleton, and the like. Among these, the photo-orientable 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 preferable.

(In formula (3), R ¹¹ and R ¹² are each independently a hydrogen atom, a fluorine atom, a cyano group, an alkyl group having 1 to 3 carbon atoms, or a fluoroalkyl group having 1 to 3 carbon atoms, and R 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. group. a is an integer from 0 to 4. When a is 2 or more, multiple R ^13s are the same group or different groups. "*" represents a bond.)

In the structure represented by the above formula (3), R ¹¹ and R ¹² are both hydrogen atoms, or one is a hydrogen atom and the other (preferably R ¹² ) is preferably an alkyl group having 1 to 3 carbon atoms.
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.

（式（４）中、Ｘ^１は、式（３）中のフェニル基に結合している場合には、単結合、炭素数１～３のアルカンジイル基、酸素原子、硫黄原子、－ＣＨ＝ＣＨ－、－ＮＨ－、－ＣＯＯ－又は－ＯＣＯ－であり、式（３）中のカルボニル基に結合している場合には、単結合、炭素数１～３のアルカンジイル基、酸素原子、硫黄原子又は－ＮＨ－である。Ｒ^１４は、単結合、置換若しくは無置換のフェニレン基、又は置換若しくは無置換のシクロヘキシレン基であり、Ｒ^１５は、置換若しくは無置換のフェニレン基、又は置換若しくは無置換のシクロヘキシレン基である。Ｒ^１６は、フェニル基若しくはシクロヘキシル基であるか、又はフェニル基若しくはシクロヘキシル基の少なくとも１個の水素原子が、炭素数１～１０のアルキル基、炭素数１～１０のアルコキシ基、少なくとも１個の水素原子がフッ素原子若しくはシアノ基で置換された炭素数１～１０の置換アルキル基、少なくとも１個の水素原子がフッ素原子若しくはシアノ基によって置換された炭素数１～１０の置換アルコキシ基、フッ素原子、又はシアノ基で置換された１価の基である。ｒは０～３の整数である。ｒが２以上の場合、複数のＲ^１５は、同一の基又は異なる基である。「＊」は結合手であることを表す。）In that the pretilt angle of the obtained liquid crystal element can be more suitably controlled, one of the two bonds "*" in the above formula (3) has at least one benzene ring and a cyclohexane ring in total. It is preferable to bond to a group having the above, and more preferably to a group having a total of two or more of at least one of a benzene ring and a cyclohexane ring. Specifically, one of the two bonds "*" in the above formula (3) is preferably a bond with a group represented by the following formula (4).

(In formula (4), when X ¹ is bonded to the phenyl group in formula (3), it 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-, and when bonded to the carbonyl group in formula (3), a single bond, an alkanediyl group having 1 to 3 carbon atoms, an oxygen atom, is a sulfur atom or -NH-.R ¹⁴ is a single bond, a substituted or unsubstituted phenylene group, or a substituted or unsubstituted cyclohexylene group, and R ¹⁵ is a substituted or unsubstituted phenylene group, or a substituted or an unsubstituted cyclohexylene group. R ¹⁶ is a phenyl group or a cyclohexyl group, or at least one hydrogen atom of the phenyl group or cyclohexyl group is an alkyl group having 1 to 10 carbon atoms, or an alkyl group having 1 to 10 carbon atoms. ~10 alkoxy groups, substituted alkyl groups with 1 to 10 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom or a cyano group, carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom or a cyano group It is a monovalent group substituted with 1 to 10 substituted alkoxy groups, fluorine atoms, or cyano groups. r is an integer of 0 to 3. When r is 2 or more, multiple R ^15s are the same group or a different group. "*" indicates a bond.)

In the above formula (4), the substituent bonded to the ring of the phenylene group and 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 a phenyl group or cyclohexyl group is substituted with 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, more preferably 3 or more carbon atoms.

A ² in the above formulas (1) and (2) is a hydroxyl group or a group “-OR ¹⁷ ” (wherein R ¹⁷ is a carbon number A monovalent hydrocarbon group having 1 to 10 carbon atoms) is preferred, a hydroxyl group or an alkoxy group having 1 to 3 carbon atoms is more preferred, and a hydroxyl group or a methoxy group is even more preferred.

The monomer (R1) has a saturated heterocycle containing -CO-N(A ¹ )-CO- or a structure in which the saturated heterocycle is opened. n1+n2 in the above formulas (1) and (2) is preferably 1 or more, and more preferably an integer from 1 to 6. The monomer (R1) is a ring-opened compound of the compound represented by the above formula (2), that is, the compound represented by the above formula (1), in that a polymer having better solubility in a solvent can be obtained. Body is preferred.

In the above formula (1) and the above formula (2), one of R ¹ and ^{R 2 is} a monovalent group having a polymerizable group, and ^the other is a hydrogen atom or a monovalent organic group. group, or represents a ring structure (hereinafter also referred to as "ring structure X") formed by combining R ¹ and R ² together with the nitrogen atom to which R ¹ and R ² are bonded. However, ring structure X has a polymerizable carbon-carbon unsaturated bond within the ring. The polymerizable group that one of R ¹ and R ² has and the polymerizable carbon-carbon unsaturated bond that ring structure X has can be selected depending on 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. It may be a polymer (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 using a monomer (R1) whose polymerizable group is a group containing a carbon-carbon unsaturated bond.

（式（５）中、Ｙ^１は、ビニルフェニル基、（メタ）アクリロイルオキシ基、（メタ）アクリロイルアミノ基、ビニル基、ビニルオキシ基、又はマレイミド基であり、Ｒ^１８は、単結合、炭素数１～２０の２価の炭化水素基であり、Ｘ^２は、単結合、－ＣＯ－、＊^１－Ｏ－ＣＯ－、又は＊^１－ＮＨ－ＣＯ－（ただし、「＊^１」はＲ^１８との結合手を表す。）である。「＊」は、式（１）又は式（２）中の窒素原子との結合手であることを表す。）In the monomer (R1) used in the synthesis of the addition polymer (A1), one of R ¹ and R ² is a monovalent group having a polymerizable group, and the other is a hydrogen atom or a monovalent organic group. When it is a group, the monovalent group having a polymerizable group is preferably a group represented by the following formula (5).

(In formula (5), Y ¹ is a vinyl phenyl group, (meth)acryloyloxy group, (meth)acryloylamino group, vinyl group, vinyloxy group, or maleimide group, and R ¹⁸ is a single bond, carbon number It is a divalent hydrocarbon group of 1 to 20, and X ² is a single bond, -CO-, * ¹ -O-CO-, or * ¹ -NH-CO- (however, "* ¹ " is R ¹⁸ "*" represents a bond with the nitrogen atom in formula (1) or formula (2).)

In the monomer (R1) used for the synthesis of the addition polymer (A1), when R ¹ and R ² are combined with each other to constitute a ring structure X, the ring structure X may be a monocyclic ring. It may be polycyclic (including fused rings and bridged rings). The ring structure X preferably has 4 to 15 carbon atoms, more preferably 4 to 12 carbon atoms.

（式中、「＊」は結合手であることを表す。）Preferred specific examples of the ring structure X include monocyclic structures represented by each of the following formulas (x1-1) to (x1-4); each of the following formulas (x2-1) to (x2-8); Examples include polycyclic structures represented by the following.

(In the formula, "*" represents a bond.)

（式（ｒ１－１）～（ｒ１－２９）中、Ｒ^２０は、炭素数１～１０のアルキル基、炭素数１～１０のアルコキシ基、少なくとも１個の水素原子がフッ素原子若しくはシアノ基で置換された炭素数１～１０の置換アルキル基、少なくとも１個の水素原子がフッ素原子若しくはシアノ基によって置換された炭素数１～１０の置換アルコキシ基、フッ素原子、又はシアノ基である。Ｒ^２１は、水素原子又はメチル基である。Ｒ^２２は、炭素数１～１０のアルカンジイル基である。）Specific examples of the monomer (R1) used in the synthesis of the addition polymer (A1) include the following formulas (r1-1) to (r1-29) as compounds represented by the above formula (1). As the compound represented by the above formula (2), for example, the succinimide ring or glutaric compound represented by each of the following formulas (r1-1) to (r1-29) has Examples include compounds in which the imide ring is opened (ring-opened product).

(In formulas (r1-1) to (r1-29), R ²⁰ is an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or at least one hydrogen atom is a fluorine atom or a cyano group. A substituted alkyl group having 1 to 10 carbon atoms, a substituted alkoxy group having 1 to 10 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom or a cyano group, a fluorine atom, or a cyano group.R ²¹ is a hydrogen atom or a methyl group. ^R22 is an alkanediyl group having 1 to 10 carbon atoms.)

（式（Ｒ－１）及び式（Ｒ－２）中、Ｒ^１、Ｒ^２、Ａ^１、ｎ１及びｎ２は、上記式（１）及び式（２）と同義である。）Monomer (R1) can be synthesized according to conventional methods of organic chemistry. As an example, a compound represented by the following formula (R-1) is synthesized using an aminoalkanedioic acid (for example, 2-aminobutanoic acid, 2-aminopentanedioic acid, etc.) as a raw material, and further, a compound represented by the following formula (R-1) is synthesized using the following formula (R-1). A compound represented by the above formula (2) can be obtained by reacting a compound represented by R-1) with a compound represented by the following formula (R-2). Furthermore, the compound represented by the above formula (1) can be obtained by ring-closing the compound represented by the above formula (2) in the presence of a catalyst (e.g., zinc chloride, silylation agent, etc.) as necessary. Obtainable. However, the method for synthesizing the monomer (R1) is not limited to the above.

(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) above.)

The content ratio of the structural unit U1 in the addition polymer (A1) is determined based on the total monomer units contained in the addition polymer (A1) from the viewpoint of improving the pretilt angle characteristics (initial pretilt angle and post-bake margin). , is preferably 1 mol% or more, more preferably 2 mol% or more, and even more preferably 5 mol% or more. Further, the content ratio of the structural unit U1 can be arbitrarily set within a range of 100 mol% or less with respect to all monomer units possessed by the addition polymer (A1). When introducing another structural unit different from the structural unit U1, the content ratio of the structural unit U1 is preferably 90 mol% or less, and 80 It is more preferably at most mol%, even more preferably at most 60 mol%, particularly preferably at most 50 mol%. In addition, the number of structural units U1 that the addition polymer (A1) has may be one type or two or more types.

(Other structural units)
The addition polymer (A1) may have only the structural unit U1, but together with the structural unit U1, a structural unit derived from a monomer different from the monomer (R1) (hereinafter referred to as "other structural unit") (also referred to as "unit"). The addition polymer (A1) has at least one type selected from 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 as other structural units. It is preferable to have a structural unit derived from.

（式（ｚ－１）及び式（ｚ－２）中、Ｒ^３１、Ｒ^３２、Ｒ^３４及びＲ^３５は、それぞれ独立して、水素原子又はメチル基である。Ｒ^３３及びＲ^３６は、それぞれ独立して１価の有機基である。）The maleimide structure-containing compound is not particularly limited as long as it is a compound having a maleimide ring or an open ring thereof. Specific examples of the compound containing a maleimide structure include a compound represented by the following formula (z-1) and a compound represented by the following formula (z-2).

(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 (It is independently a monovalent organic group.)

In the above formulas (z-1) and (z-2), the monovalent organic groups R ³³ and R ³⁶ include a monovalent hydrocarbon group having 1 to 40 carbon atoms, and at least one of the hydrocarbon groups. methylene groups are substituted with -O-, -CO-, -COO-, -NR ²⁶ - or -CONR ²⁶ - (wherein R ²⁶ is a hydrogen atom or a monovalent hydrocarbon group) group (hereinafter also referred to as "group β"), a monovalent hydrocarbon group having 1 to 40 carbon atoms, or at least one hydrogen atom of group β is a fluorine atom, a cyano group, a carboxyl group, an epoxy group, a hydroxyl group Or a group substituted with a substituent such as a cyclic carbonate group can be mentioned. The monovalent organic group of R ³³ and R ³⁶ is preferably a group having a photo-alignable group, a group having a vertically-aligning 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-alignable group, the group having the photo-alignable group is a group having a cinnamic acid structure represented by the above formula (3). It is preferable.

Here, the "vertical alignment group" is a functional group that imparts a function of inducing a desired pretilt angle in liquid crystal molecules to a coating film formed using a liquid crystal alignment agent. This vertical alignment group exhibits a property of vertically aligning liquid crystal molecules without being irradiated with light. 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 fluoroalkoxy group having 4 to 40 carbon atoms, 2 The above rings (preferably 1,4-phenylene group and 1,4-cyclohexylene group) can be a single bond or a divalent linking group (-O-, -COO-, alkanediyl group having 1 to 3 carbon atoms, etc.) ), a group having a carbon number of 12 to 50 and a group having a steroid skeleton and a carbon number of 17 to 51, and the like.

Examples of maleimide structure-containing compounds include N-methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, 4-carboxyphenylmaleimide, 2-methylphenylmaleimide, 4-hydroxyphenylmaleimide, N-dodecylmaleimide, N- Examples include cholestanyloxycarbonylphenylmaleimide, and compounds in which the maleimide rings of these compounds are opened (ring-opened products).

The (meth)acrylic compound only needs to have a (meth)acryloyl group, and the remaining structure is not particularly limited. Specific examples of (meth)acrylic compounds include (meth)acrylic acid, α-ethyl acrylic acid, maleic acid, fumaric acid, itaconic acid, alkyl (meth)acrylate, cycloalkyl (meth)acrylate, and (meth)acrylic acid. Benzyl acrylate, 2-ethylhexyl (meth)acrylate, glycidyl (meth)acrylate, α-ethyl glycidyl acrylate, α-n-propyl glycidyl acrylate, α-n-butyl glycidyl acrylate, (meth)acrylic 3,4-epoxybutyl acid, α-ethyl acrylate 3,4-epoxybutyl, (meth)acrylic acid 3,4-epoxycyclohexylmethyl, (meth)acrylate 6,7-epoxyheptyl, α-ethyl acrylate 6,7-Epoxyheptyl, 4-hydroxybutyl glycidyl acrylate, (3-ethyloxetan-3-yl)methyl (meth)acrylate, propylene carbonate (meth)acrylate, 3-hydroxy-1-adamantyl (meth) Examples include acrylate.

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

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

When ^A1 in the structural unit U1 is a monovalent group having a photoalignable group, from the viewpoint of suppressing the pretilt angle expressed by the liquid crystal alignment film from becoming too high, the addition polymer (A1) is Together with the structural unit U1, at least one type selected from 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 a photo-alignable group. It is preferable to have a structural unit (hereinafter also referred to as "structural unit U2") derived from a monomer that does not have.

When ^A1 is a monovalent group having a photo-alignable group, the content ratio of the structural unit U2 in the addition polymer (A1) is 50 mol with respect to all monomer units possessed by the addition polymer (A1). % or more, more preferably 55 mol% or more, and even more preferably 60 mol% or more. Further, the content ratio of the structural unit U2 is preferably 99 mol% or less, more preferably 98 mol% or less, and 95 mol% or less, based on the total monomer units that the addition polymer (A1) has. It is more preferable that it is the following. Note that the addition polymer (A1) may have only one type of structural unit U2, or may have two or more types.

(Cyclic ether structure and cyclic carbonate structure)
The addition polymer (A1) is selected from the group consisting of a cyclic ether structure and a cyclic carbonate structure in that it can further reduce variations in pretilt angle (post-bake margin) due to differences in heating temperature (post-bake temperature) during film formation. It is preferable to have a structural unit (hereinafter also referred to as "structural unit U3") derived from a monomer having at least one type of structural unit U3. Examples of the cyclic ether structure include an oxetane ring structure and an oxirane ring structure. Examples of the cyclic carbonate structure include an ethylene carbonate structure and a propylene carbonate structure. 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 oxetane ring structure or an oxirane ring structure. preferable.

The structural unit U3 is preferably a structural unit derived from at least one selected from the group consisting of (meth)acrylic compounds, maleimide structure-containing compounds, and styrene structure-containing compounds. Among these, a structural unit derived from at least one selected from the group consisting of a (meth)acrylic compound and a styrene structure-containing compound is more preferable, since there is a high degree of freedom in selecting the monomer. In addition, the structural unit U3 may constitute at least a part of the structural unit U2 that the addition polymer (A1) has.

When the addition polymer (A1) has a structural unit U3, the proportion of the structural unit U3 is preferably 2 mol% or more, and 5 mol% or more, based on the total monomer units that the addition polymer (A1) has. % or more, more preferably 10 mol% or more, even more preferably 20 mol% or more. Further, the content of the structural unit U3 is preferably 90 mol% or less, more preferably 85 mol% or less, and 70 mol% or less based on the total monomer units that the addition polymer (A1) has. It is more preferable that Note that the addition polymer (A1) may have only one type of structural unit U3, or may have two or more types.

(Reactive functional group)
From the viewpoint of increasing the effect of improving the post-bake margin, the addition polymer (A1) contains a functional group (hereinafter also referred to as "reactive functional group") that reacts with at least one of a cyclic ether structure and a cyclic carbonate structure. It is preferable to have. Examples of the reactive functional group include a carboxyl group, a hydroxyl group, an isocyanate group, an amino group, and a group in which each of these groups is protected with a protecting group. Among the reactive functional groups, those selected from the group consisting of carboxyl groups and protected carboxyl groups (hereinafter also referred to as "protected carboxyl groups") have good storage stability and high reactivity upon heating. It is preferable that it is at least one selected one.

（式（６）中、Ｒ^４１、Ｒ^４２及びＲ^４３は、下記（ｉ）又は（ｉｉ）を満たす。
（ｉ）Ｒ^４１、Ｒ^４２及びＲ^４３は、それぞれ独立して、炭素数１～１０のアルキル基若しくは炭素数３～２０の１価の脂環式炭化水素基である。
（ｉｉ）Ｒ^４１及びＲ^４２は、Ｒ^４１とＲ^４２とが互いに合わせられて、Ｒ^４１及びＲ^４２が結合する炭素原子と共に構成される炭素数４～２０の２価の脂環式炭化水素基又は環状エーテル基を表す。Ｒ^４３は、炭素数１～１０のアルキル基、炭素数２～１０のアルケニル基又は炭素数６～２０のアリール基である。「＊」は結合手であることを表す。）The protected carboxyl group is not particularly limited as long as it can be removed by heat to generate a carboxyl group. Preferred specific examples of the protected carboxyl group include a structure represented by the following formula (6), a carboxylic acid acetal ester structure, a carboxylic acid ketal ester structure, and the like.

(In formula (6), R ⁴¹ , R ⁴² and R ⁴³ satisfy the following (i) or (ii).
(i) R ⁴¹ , R ⁴² and R ⁴³ are each independently an alkyl group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.
(ii) R ⁴¹ and R ⁴² are a divalent alicyclic hydrocarbon having 4 to 20 carbon atoms formed by combining R ⁴¹ and R ⁴² together with the carbon atom to which R ⁴¹ and R ⁴² are bonded. group or a cyclic ether group. 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. "*" indicates a bond. )

The monomer having a reactive functional group is preferably at least one selected from the group consisting of (meth)acrylic compounds, maleimide structure-containing compounds, and styrene structure-containing compounds. Among these, at least one selected from the group consisting of (meth)acrylic compounds and styrene structure-containing compounds is more preferable since there is a high degree of freedom in selecting monomers.

When the addition polymer (A1) has a structural unit (hereinafter also referred to as "structural unit U4") derived from a monomer having a reactive functional group, the proportion of the structural unit U4 is higher than that of the addition polymer (A1). ) is preferably 2 mol % or more, more preferably 5 mol % or more, and even more preferably 10 mol % or more, based on the total monomer units possessed by ). Further, the content of the structural unit U4 is preferably 70 mol% or less, more preferably 60 mol% or less, and 50 mol% or less, based on the total monomer units that the addition polymer (A1) has. It is more preferable that it is the following. In addition, the structural unit U4 may constitute at least a part of the structural unit U2 that the addition polymer (A1) has. The addition polymer (A1) may have only one type of structural unit U4, or may have two or more types.

(Photosensitizing structure)
The polymer (A) may have a partial structure (hereinafter also referred to as "photosensitizing structure") capable of exhibiting a photosensitizing function that exhibits a sensitizing effect upon irradiation with light. When the polymer (A) has a photosensitizing structure, it is preferable because it is possible to obtain a liquid crystal aligning film with smaller variations in pretilt angle due to differences in heating temperature during film formation. Here, the term "photosensitizing function" refers to a function in which, after being brought into a singlet excited state by irradiation with light, intersystem crossing occurs rapidly to transition to a triplet excited state. When it collides with another molecule in this triplet state, it turns the other molecule into an excited state and returns to its ground state.

The photosensitizing structure possessed by the polymer (A) is not particularly limited, but includes, for example, an acetophenone structure, a benzophenone structure, an anthraquinone structure, a biphenyl structure, a terphenyl structure, a carbazole structure, a 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. It is preferable that the polymer (A) 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. It is preferable to carry out polymerization using a polymer. Specific examples of the monomer having a photosensitizing structure include a compound represented by the following formula (9).
Y ² -L ¹ -Y ³ ...(9)
(In formula (9), Y ² is a vinyl phenyl group, (meth)acryloyloxy group, (meth)acryloylamino group, vinyl group, vinyloxy group, or maleimide group, and L ¹ is a single bond or a divalent It is a linking group, and ^Y3 is a group having a photosensitizing structure.)

In the above formula (9), Y ² is preferably a (meth)acryloyloxy group or a (meth)acryloylamino group, and more preferably a (meth)acryloyloxy group, since the degree of freedom in selecting a monomer can be increased. The divalent linking group L ¹ 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 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, Alternatively, a 1,4-dioxocyclohexa-2,5-diene structure is preferred.

When the addition polymer (A1) has a structural unit derived from a monomer having a photosensitizing structure (hereinafter also referred to as "structural unit U5"), the proportion of the structural unit U5 is higher than that of the addition polymer (A1). ) is preferably 1 mol % or more, more preferably 2 mol % or more, and even more preferably 3 mol % or more, based on the total monomer units possessed by ). Further, the content of the structural unit U5 is preferably 50 mol% or less, more preferably 40 mol% or less, and 30 mol% or less based on the total monomer units that the addition polymer (A1) has. It is more preferable that In addition, the structural unit U5 may constitute at least a part of the structural unit U2 that the addition polymer (A1) has. The addition polymer (A1) may have only one type of structural unit U5, or may have two or more types.

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

In the above polymerization reaction, the reaction temperature is preferably 30°C to 120°C, and the reaction time is preferably 1 to 36 hours. The amount of organic solvent used (a) should be such that the total amount of monomers used in the reaction (b) is 0.1 to 60% by mass based on the total amount of the reaction solution (a + b). is preferred. The reaction solution obtained by dissolving the polymer can be prepared using known methods such as pouring the reaction solution into a large amount of poor solvent and drying the resulting precipitate under reduced pressure, or distilling the reaction solution off under reduced pressure using an evaporator. The addition polymer (A1) contained in the reaction solution may be isolated using a separation method and then used for preparing a liquid crystal aligning agent.

The weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) of the addition polymer (A1) is preferably 1,000 to 300,000, more preferably 2,000 to 100, It is 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. In addition, the addition polymer (A1) used for preparation of a liquid crystal aligning agent may be one type, and may combine two or more types.

(condensation polymer)
The condensation polymer (A2) may be any polymer obtained using a monomer having a group capable of condensation polymerization as a polymerizable group, and its main skeleton is not particularly limited. The condensation polymer (A2) is a polyorganosiloxane having a structural unit U1 (hereinafter also referred to as "polyorganosiloxane (A)") because it has a high effect of improving the coating uniformity and pretilt angle characteristics of the resulting liquid crystal alignment film. .) is preferable. The polyorganosiloxane (A) contains a hydrolyzable silane compound (hereinafter also referred to as "specific silane compound") represented by the above formula (1) or the above formula (2) as the monomer (R1). It can be obtained by a hydrolysis/condensation reaction using

（式（７）及び式（８）中、Ｒ^２３は炭素数１～２０の２価の炭化水素基であり、Ｒ^２４及びＲ^２５は、それぞれ独立して、炭素数１～１０の１価の炭化水素基であり、Ｒ^２７は水素原子又は１価の有機基である。ｋは１～３の整数である。Ａ^１、Ａ^２、ｎ１及びｎ２は、上記式（１）及び式（２）と同義である。）In the specific silane compound, one of R ¹ and R ² in the above formulas (1) and (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).

(In formula (7) and formula (8), R ²³ is a divalent hydrocarbon group having 1 to 20 carbon atoms, and R ²⁴ and R ²⁵ are each independently a monovalent hydrocarbon group having 1 to 10 carbon atoms. is a hydrocarbon group, and R ²⁷ is a hydrogen atom or a monovalent organic group. k is an integer of 1 to 3. A ¹ , A ² , n1 and n2 are represented by the above formula (1) and the formula ( It is synonymous with 2).)

（上記式（ｓ１－１）～式（ｓ１－１０）中、Ｒ^２３、Ｒ^２４、Ｒ^２５及びｋは、上記式（７）と同義である。Ｒ^２０は、炭素数１～１０のアルキル基、炭素数１～１０のアルコキシ基、少なくとも１個の水素原子がフッ素原子若しくはシアノ基で置換された炭素数１～１０の置換アルキル基、少なくとも１個の水素原子がフッ素原子若しくはシアノ基によって置換された炭素数１～１０の置換アルコキシ基、フッ素原子、又はシアノ基である。）Specific examples of the specific silane compound include compounds represented by each of the following formulas (s1-1) to (s1-10).

(In the above formulas (s1-1) to (s1-10), R ²³ , R ²⁴ , R ²⁵ and k have the same meanings as in the above formula (7). R ²⁰ is an alkyl group having 1 to 10 carbon atoms. group, 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 with a fluorine atom or a cyano group, and a substituted alkyl group in which at least one hydrogen atom is substituted with a fluorine atom or a cyano group. A substituted alkoxy group having 1 to 10 carbon atoms, a fluorine atom, or a cyano group.)

When synthesizing polyorganosiloxane (A), only specific silane compounds may be used as hydrolysable silane compounds, but hydrolysable silane compounds other than specific silane compounds (hereinafter also referred to as "other silane compounds") may be used. ) may be used together.

Other silane compounds are not particularly limited as long as they can undergo condensation polymerization with a specific silane compound, but examples include tetraalkoxy or alkylalkoxysilane compounds such as tetramethoxysilane, methyltriethoxysilane, and dimethyldiethoxysilane; cyclohexyltrimethoxysilane , cycloalkylalkoxysilane compounds such as cyclohexylmethyldimethoxysilane; arylalkoxysilane compounds such as phenyltrimethoxysilane and phenyltriethoxysilane; 3-mercaptopropyltriethoxysilane, mercaptomethyltriethoxysilane, 3-aminopropyltrimethoxysilane , N-(3-cyclohexylamino)propyltrimethoxysilane and other nitrogen- and sulfur-containing alkoxysilane compounds; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyl Epoxy group-containing silane compounds such as dimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane; 3-(meth)acryloxypropyltrimethoxy Unsaturated bond-containing alkoxysilane compounds such as silane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, vinyltriethoxysilane, p-styryltrimethoxysilane; trimethoxy Examples include silane compounds containing acid anhydride groups such as silylpropylsuccinic anhydride; silane compounds containing isocyanate groups such as 3-isocyanatepropyltrimethoxysilane and 3-isocyanatepropyltriethoxysilane. As other silane compounds, one type of these can be used alone or two or more types can be used in combination. Note that "(meth)acrylo" includes "acrylo" and "methacrylo".

The content ratio of the structural unit U1 in the polyorganosiloxane (A) is determined based on the total monomer units possessed by the polyorganosiloxane (A) from the viewpoint of improving the pretilt angle characteristics (initial pretilt angle and post-bake margin). The content is preferably 1 mol% or more, more preferably 2 mol% or more, and even more preferably 5 mol% or more. Further, the content ratio of the structural unit U1 is preferably 90 mol% or less, more preferably 80 mol% or less, and 60 mol% or less, based on the total monomer units that the polyorganosiloxane (A) has. % or less is more preferable. In addition, the number of structural units U1 that the polyorganosiloxane (A) has may be one type or two or more types.

The above-mentioned hydrolysis/condensation reaction is carried out by reacting one or more of the above-mentioned hydrolyzable silane compounds with water, preferably in the presence of a suitable catalyst and organic solvent. In the reaction, the proportion of water used is preferably 1 to 30 mol per 1 mol of the silane compound (total amount). Examples of the catalyst used include acids, alkali metal compounds, organic bases, titanium compounds, and zirconium compounds. The amount of the catalyst used varies depending on the type of catalyst, reaction conditions such as temperature, and should be set appropriately, but is preferably 0.01 to 3 times the mole amount relative to the total amount of the silane compound. . Examples of the organic solvent used include hydrocarbons, ketones, esters, ethers, alcohols, etc. Among these, it is preferable to use water-insoluble or poorly water-soluble organic solvents. The proportion of the organic solvent to be used is preferably 10 to 10,000 parts by weight based on a total of 100 parts by weight of the silane compound used in the reaction.

The above hydrolysis/condensation reaction is preferably carried out by heating, for example, in an oil bath. At this time, the heating temperature is preferably 130° C. or lower, and the heating time is preferably 0.5 to 12 hours. After the reaction is completed, the organic solvent layer separated from the reaction solution is dried with a desiccant if necessary, and then the solvent is removed to obtain the desired polyorganosiloxane. Note that the method for synthesizing polyorganosiloxane is not limited to the above-mentioned hydrolysis/condensation reaction, but may also be carried out by, for example, a method in which a hydrolyzable silane compound is reacted in the presence of oxalic acid and alcohol.

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

In the liquid crystal aligning agent of the present disclosure, the content ratio of the polymer (A) is determined from the viewpoint of making the pre-tilt angle characteristics (initial pre-tilt angle, post-bake margin) excellent while sufficiently increasing the applicability to the substrate. It is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, based on the total polymer contained in the liquid crystal aligning agent. Moreover, the content rate of a polymer (A) can be suitably set within the range of 100 mass % or less with respect to the total polymer contained in a liquid crystal aligning agent. According to the polymer (A), even if the amount used is reduced, the effect of improving coating uniformity and pretilt angle characteristics can be obtained. From the viewpoint of sufficiently improving the reliability while reducing the cost of the liquid crystal aligning agent, the content ratio of the polymer (A) is 90% by mass or less with respect to the total amount of the polymer contained in the liquid crystal aligning agent. The content is preferably 70% by mass or less, more preferably 50% by mass or less.

<Other ingredients>
The liquid crystal aligning agent of the present disclosure may contain other components other than the polymer (A), if necessary.

(Other polymers)
The liquid crystal aligning agent of the present disclosure includes, as a polymer component, a polymer (hereinafter also referred to as "other polymer") that does not have a structural unit derived from the monomer (R1) together with the polymer (A). ) may be included. Other polymers are not particularly limited, but at least one type of polymer selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, and polyurea (hereinafter also referred to as "polymer (B)") is preferably used. can. It is preferable to use the polymer (B) together with the polymer (A) in that the liquid crystal orientation and electrical properties of the obtained liquid crystal element can be ensured. The 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 a polyamic acid, the polyamic acid can be obtained by reacting a tetracarboxylic dianhydride and a diamine compound. At this time, conventionally known compounds used in the synthesis of polyamic acids can be used as the tetracarboxylic dianhydride and diamine compound. Polyamic acid esters can be produced, for example, by reacting the polyamic acid obtained above with an esterifying agent (for example, methanol, ethanol, N,N-dimethylformamide diethyl acetal, etc.); by reacting a tetracarboxylic diester with a diamine compound; It can be obtained by a method of reacting in the presence of a suitable dehydration catalyst; a method of reacting a tetracarboxylic acid diester dihalide and a diamine in the presence of a suitable base, and the like. Polyimide can be obtained, for example, by dehydrating and ring-closing the polyamic acid obtained above and imidizing it. The imidization rate of polyimide is preferably 20 to 90%, more preferably 30 to 80%.

The weight average molecular weight (Mw) of the polymer (B) measured by GPC in terms of polystyrene is preferably 1,000 to 500,000, more preferably 2,000 to 300,000. The molecular weight distribution (Mw/Mn) is preferably 7 or less, more preferably 5 or less.

When the polymer (B) is contained in the liquid crystal aligning agent together with the polymer (A) as a polymer component, the content ratio of the polymer (B) is set such that the content ratio of the polymer (B) is sufficient to achieve the effect of improving the pretilt angle characteristics by blending the polymer (A). From the viewpoint of obtaining good liquid crystal alignment while also obtaining a good liquid crystal orientation, it is preferable to use 100 parts by mass or more with respect to 100 parts by mass of the polymer (A) in the liquid crystal aligning agent. The content of the polymer (B) is more preferably 100 to 2000 parts by mass, and still more preferably 200 to 1500 parts by mass. In addition, as the polymer (B), one type may be used alone or two or more types may be used in combination.

(Photosensitizer)
The liquid crystal aligning agent of the present disclosure preferably contains a compound having a photosensitizing structure (hereinafter also referred to as "photosensitizer"). The photosensitizer may be a polymer (A) having a structural unit derived from the monomer (R1) and a photosensitizing structure, another polymer, or a polymer. It may be an additive component (hereinafter also referred to as "additive (S)") that is blended separately from the other components. Moreover, the liquid crystal aligning agent may 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 acetophenone structure-containing compounds such as acetophenone, acetophenone benzyl ketal, 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 ketone) ), etc.; 3,5-dinitrobenzene, 4-methyl-3,5-dinitrobenzene, 3-(3,5-dinitrophenoxy)propyl, 2-methyl-3,5-dinitrobenzene, etc. Nitroaryl structure-containing compounds; Hydrocarbons such as naphthalene, anthracene, biphenyl, terphenyl, 2,3-benzofluorene, pyrene, perylene, fluorene, anthraquinone; 9,10-dioxo-9,10-dihydroanthracene, 3- Anthracene derivatives such as (9,10-dioxo-9,10-dihydroanthracen-2-yl)propyl and 2-oxo-9,10-dihydroanthracene; amino group-containing compounds such as triphenylamine and carbazole; thioxanthone and diethyl Sulfur-containing compounds such as thioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one; 2,4,6-trimethylbenzoyl Examples include phosphorus-containing compounds such as diphenylphosphine oxide and bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide. In addition, as the additive (S), one type may be used alone, or two or more types may be used in combination.

When using the additive (S) as a photosensitizer, the content ratio of the additive (S) in the liquid crystal aligning agent should be determined by adjusting the content of the additive (S) in the polymer component in the liquid crystal aligning agent from the viewpoint of further increasing the effect of reducing the post-bake margin. It is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, based on 100 parts by mass of the total amount. In addition, the content ratio of the additive (S) is preferably 30 parts by mass or less, and 20 parts by mass or less, based on 100 parts by mass of the total amount of the polymer component, from the viewpoint of suppressing performance deterioration caused by addition of an excessive amount. It is more preferable that the amount is less than parts by mass.

(solvent)
The liquid crystal aligning agent of the present disclosure is prepared as a solution composition in which a polymer component and optionally blended components are preferably dissolved in an organic solvent. Examples of the organic solvent used include aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons. The solvent component may be one type of these or a mixed solvent of two or more types.

（式（Ｄ－１）中、Ｒ^１は、炭素数１～４のアルキル基又はＣＨ_３ＣＯ－であり、Ｒ^２は、炭素数１～４のアルカンジイル基又は－（ＣＨ_２ＣＨ_２Ｏ）ｎ－ＣＨ_２ＣＨ_２－（ただし、ｎは１～４の整数）であり、Ｒ^３は、水素原子又は炭素数１～４のアルキル基である。）

（式（Ｄ－２）中、Ｒ^４は、炭素数１～３のアルカンジイル基である。）

（式（Ｄ－３）中、Ｒ^５及びＲ^６は、それぞれ独立に炭素数４～８のアルキル基である。）The solvent component of the liquid crystal aligning agent is a 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). At least one solvent selected from the following and having a boiling point of 180° C. or less at 1 atmosphere (hereinafter also referred to as "specific solvent") can be preferably used. By using a specific solvent as at least a part of the solvent component, it is possible to obtain a liquid crystal element with excellent liquid crystal orientation and electrical properties even when heating during film formation is performed at a low temperature (for example, 200° C. or lower). It is preferable.

(In formula (D-1), R ¹ is an alkyl group having 1 to 4 carbon atoms or CH ₃ CO-, and R ² is an alkanediyl group having 1 to 4 carbon atoms or -(CH ₂ CH ₂ O ) n-CH ₂ CH ₂ - (where n is an integer of 1 to 4), and R ³ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)

(In formula (D-2), R ⁴ is an alkanediyl group having 1 to 3 carbon atoms.)

(In formula (D-3), R ⁵ and R ⁶ are each independently an alkyl group having 4 to 8 carbon atoms.)

Specific examples of specific solvents include propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, diethylene glycol methyl ethyl ether, 3-methoxy-1-butanol, and ethylene glycol monomethyl ether as compounds represented by the above formula (D-1). , ethylene glycol monoethyl ether, ethylene glycol monopropyl 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, etc.;
As the compound represented by the above formula (D-2), cyclobutanone, cyclopentanone, cyclohexanone;
Examples of the compound represented by the above formula (D-3) include diisobutyl ketone and the like. In addition, as the specific solvent, one type may be used alone, or two or more types may be used in combination.

Although the solvent component of the liquid crystal aligning agent may consist only of a specific solvent, it may be a mixed solvent of the specific solvent and another solvent other than the specific solvent. Other solvents include, for example, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,2-dimethyl-2-imidazolidinone, γ-butyrolactone, γ-butyrolactam, N,N-dimethylformamide, In addition to highly polar solvents such as N,N-dimethylacetamide,
4-Hydroxy-4-methyl-2-pentanone, butyl lactate, butyl acetate, methylmethoxypropionate, ethyl ethoxypropionate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether Examples include acetate, isoamyl propionate, isoamyl isobutyrate, diisopentyl ether, ethylene carbonate, propylene carbonate, cyclohexane, octanol, and tetrahydrofuran. These can be used alone or in combination of two or more.

Regarding the solvent component contained in the liquid crystal aligning agent, the content ratio of the specific solvent is preferably 20% by mass or more, and 40% by mass or more with respect to the total amount of the solvent contained in the liquid crystal aligning agent. is more preferable, and even more preferably 50% by mass or more.

In addition to the above, other components to be included in the liquid crystal aligning agent include, for example, functional silane compounds, polyfunctional (meth)acrylates, antioxidants, metal chelate compounds, curing accelerators, surfactants, fillers, and dispersants. , photosensitizers and the like. The blending ratio of other components can be appropriately selected depending on each compound within a range that does not impair the effects of the present disclosure.

The solid content concentration in the liquid crystal aligning agent (the ratio of the total mass of components other than the solvent of the liquid crystal aligning agent to the total mass of the liquid crystal aligning agent) is appropriately selected in consideration of viscosity, volatility, etc., but is preferably It is in the range of 1 to 10% by mass. When the solid content concentration is 1% by mass or more, a coating film with sufficient thickness can be obtained, and a good liquid crystal alignment film can be easily obtained. On the other hand, when the solid content concentration is 10% by mass or less, the film thickness of the coating film does not become too excessive, and the viscosity of the liquid crystal aligning agent can be moderated, and a decrease in coating properties can be suppressed. This is suitable because it allows for

<<Liquid crystal alignment film and liquid crystal element>>
The liquid crystal aligning film of the present disclosure is formed from the liquid crystal aligning agent prepared as described above. Moreover, the liquid crystal element of this indication comprises the liquid crystal alignment film formed using the liquid crystal alignment agent demonstrated above. The operation mode of the liquid crystal in the liquid crystal element is not particularly limited, and includes, for example, TN type, STN type, VA type (including VA-MVA type, VA-PVA type, etc.), IPS (In-Plane Switching) type, FFS (Fringe type, etc.). The present invention can be applied to various modes such as a Field Switching (Field Switching) type, an OCB (Optically Compensated Bend) type, and a PSA (Polymer Sustained Alignment) type. A liquid crystal element can be manufactured, for example, by a method including steps 1 to 3 below. In step 1, the substrate used differs depending on the desired operation mode. Steps 2 and 3 are common to each operation mode.

<Step 1: Formation of coating film>
First, a liquid crystal aligning agent is applied onto a substrate, and a coating film is formed on the substrate, preferably by heating the applied surface. As the substrate, for example, a transparent substrate made of glass such as float glass or soda glass; or plastic such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, or poly(alicyclic olefin) can be used. The transparent conductive film provided on one surface of the substrate includes a NESA film (registered trademark of PPG, Inc., USA) made of tin oxide (SnO ₂ ), an ITO film made of indium oxide-tin oxide (In ₂ O ₃ -SnO ₂ ), etc. Can be used. When manufacturing a TN type, STN type, or VA type liquid crystal element, two substrates each having a patterned transparent conductive film are used. On the other hand, when manufacturing an IPS type or FFS type liquid crystal element, a substrate provided with comb-shaped patterned electrodes and a counter substrate provided with no electrodes are used. The liquid crystal aligning agent is applied to the substrate on the electrode formation surface, preferably by offset printing, flexographic printing, spin coating, roll coater, or inkjet printing.

After applying the liquid crystal aligning agent, preheating (prebaking) is preferably performed for the purpose of preventing the applied liquid crystal aligning agent from dripping. The prebake temperature is preferably 30 to 200°C, and the prebake time is preferably 0.25 to 10 minutes. After that, a baking (post-baking) step is performed for the purpose of completely removing the solvent. The firing temperature (post-bake temperature) at this time is preferably 80 to 250°C, more preferably 80 to 200°C. Post-bake time is preferably 5 to 200 minutes. In particular, when using the liquid crystal aligning agent prepared above, it has good solubility in low boiling point solvents such as specific solvents, and the post-bake temperature can be set to, for example, 200°C or lower, preferably 180°C or lower, more preferably Even when the temperature is 160° C. or lower, it is preferable because variations in pretilt angle due to differences in prebake temperature can be further reduced. The thickness of the film thus formed is preferably 0.001 to 1 μm.

<Step 2: Orientation treatment>
When manufacturing a TN type, STN type, IPS type, or FFS type liquid crystal element, a treatment (orientation treatment) for imparting liquid crystal alignment ability to the coating film formed in step 1 above is performed. Thereby, the ability to orient liquid crystal molecules is imparted to the coating film, and it becomes a liquid crystal alignment film. When manufacturing a vertical alignment type liquid crystal element, the coating film formed in step 1 above can be used as it is as a liquid crystal alignment film, but in order to further improve the liquid crystal alignment ability, the coating film may be subjected to an alignment treatment. It is recommended to apply As the alignment treatment, it is preferable to use a photoalignment treatment in which the coating film formed on the substrate is irradiated with light to impart liquid crystal alignment ability to the coating film.

Light irradiation for photo-alignment can be performed by irradiating the coating film after the post-bake process, by irradiating the coating film after the pre-bake process but before the post-bake process, or by irradiating the coating film after the pre-bake process but before the post-bake process. At least one of these methods can be carried out by irradiating the coating film while the coating film is being heated. As the radiation irradiated to the coating film, for example, ultraviolet rays and visible light including light with a wavelength of 150 to 800 nm can be used. Preferably, it is ultraviolet light containing light with a wavelength of 200 to 400 nm. If the radiation is polarized, it may be linearly polarized or partially polarized. 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 thereof. In the case of non-polarized radiation, the irradiation direction is oblique.

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

<Step 3: Construction of liquid crystal cell>
A liquid crystal cell is manufactured by preparing two substrates on which liquid crystal alignment films are formed as described above, and disposing a liquid crystal between the two substrates that are arranged facing each other. To manufacture a liquid crystal cell, for example, two substrates are placed facing each other with a gap in between so that the liquid crystal alignment films face each other, and the peripheral parts of the two substrates are bonded together using a sealant, and the surfaces of the substrates and Examples include a method of injecting liquid crystal into a cell gap surrounded by a sealant and sealing the injection hole, and a method using an ODF method. As the sealant, for example, an epoxy resin containing a hardening agent and aluminum oxide spheres as a spacer can be used. Examples of liquid crystals include nematic liquid crystals and smectic liquid crystals, and among them, nematic liquid crystals are preferred. In the PSA mode, after the liquid crystal cell is constructed, a process is performed in which the liquid crystal cell is irradiated with light while a voltage is applied between the conductive films of a pair of substrates.

Then, if necessary, a polarizing plate is attached to the outer surface of the liquid crystal cell to form a liquid crystal element. Examples of the polarizing plate include a polarizing plate in which a polarizing film called "H film" in which polyvinyl alcohol is stretched and oriented and absorbs iodine is sandwiched between cellulose acetate protective films, or a polarizing plate made of the H film itself.

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

Hereinafter, the present disclosure will be explained in more detail with reference to Examples, but the present disclosure is not limited to these Examples.

In the following Examples and Comparative Examples, the weight average molecular weight and number average molecular weight of the polymers were measured by the following methods.
[Weight average molecular weight (Mw) and number average molecular weight (Mn) of polymer]
The weight average molecular weight and number average molecular weight are polystyrene equivalent values measured by gel permeation chromatography under the following conditions.
Column: manufactured by Tosoh Corporation, TSKgelGRCXLII
Solvent: Tetrahydrofuran Temperature: 40℃
Pressure: 68kgf/ ^cm2

The structural formula of the compound used in this example is shown below. In addition, below, for convenience, "the compound represented by formula (X)" may be simply abbreviated as "compound (X)."

<Synthesis of compounds>
[Synthesis Example 1-1: Synthesis of compound (MA-2)]
Compound (MA-2) was synthesized according to the scheme below.

13.3 g of aspartic acid and 200 ml of tetrahydrofuran (THF) were added to an eggplant flask and dissolved. 9.81 g of maleic acid was added thereto, and after stirring for 1 hour, the solvent was distilled off using an evaporator. To the obtained solid were added 300 ml of toluene, 24.2 g of hexamethyldisilazane, and 27.3 g of zinc chloride, and the mixture was reacted at 80° C. for 4 hours. After the reaction, the reaction solution was separated and purified twice with hydrochloric acid (1N) and twice with water. Then, the organic layer was concentrated using an evaporator. The obtained solid was crystallized from THF/ethanol/water to obtain 14.2 g of Intermediate 1.
Intermediate 1 was dissolved in THF, and 28.6 g of cinnamate amine represented by the above formula (CA) (hereinafter referred to as "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 42.5 g of compound (MA-2).

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

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

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

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

While flowing nitrogen into a three-necked eggplant flask, 200 ml of dehydrated THF was added to 13.3 g of aspartic acid and dissolved. 15.5 g of "Karens MOI" (manufactured by Showa Denko) was added thereto, and the mixture was reacted at 50° C. for 8 hours, and the solvent was distilled off. Next, 300 ml of toluene, 24.2 g of hexamethyldisilazane, 27.3 g of zinc chloride, and 1 g of dibutylhydroxytoluene were added, and the mixture was reacted at 50° C. for 8 hours. After the reaction, the reaction solution was separated and purified twice with hydrochloric acid (1N) and twice with water. Then, the organic layer was concentrated using an evaporator. The obtained solid was crystallized from THF/ethanol/water to obtain 10.0 g of Intermediate 2.
Next, Intermediate 2 was dissolved in THF, and 14.5 g of compound CA was further added thereto, followed by reaction 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)]
It was synthesized in the same manner as compound (MA-4) except that 5-norbornene-2,3-dicarboxylic anhydride was used as the starting material.

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

In an eggplant flask, 13.3 g of aspartic acid, 10 ml of pyridine, and 150 ml of dehydrated THF were added, dissolved, and cooled on ice. 4-vinylbenzoic acid chloride dissolved in 50 ml of dehydrated THF was gradually added dropwise thereto, followed by reaction for 15 hours. After the reaction, 100 ml of ethyl acetate was added, and the mixture was purified by liquid separation twice with hydrochloric acid (1N) and twice with water. Then, the organic layer was concentrated using an evaporator. The obtained solid was crystallized from THF/ethanol/water to obtain 20.3 g of Intermediate 3.
Intermediate 3 was dissolved in THF, 32.4 g of compound CA was further added, and the mixture was reacted at 50° C. for 1 hour. After the reaction, the solvent was distilled off to obtain 51.6 g of compound (MA-6).

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

30 ml of toluene, 4.84 g of hexamethyldisilazane, and 5.45 g of zinc chloride were added to 3.46 g of N-allylaspartic acid, and the mixture was reacted at 80° C. for 4 hours. After the reaction, the reaction solution was separated and purified twice with hydrochloric acid (1N) and twice with water. Then, the organic layer was concentrated using an evaporator. The obtained solid was crystallized from 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 further added thereto, followed by reaction at 50° C. for 1 hour. After the reaction, 5.45 g of Intermediate 5 was obtained by distilling off the solvent.
Furthermore, Intermediate 5 and 300 μl of a 0.01M hexachloroplatinic (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, followed by a reaction at 70° C. for 3 days. After the reaction, the solvent was distilled off, and 3.71 g of compound (MA-7) was obtained by crystallizing from THF/ethanol.

<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 polymerization monomers, 0.70 g (7.00 mmol) of compound (MB-4), and 2. 0.10 g (0.41 mmol) of 2'-azobis(2,4-dimethylvaleronitrile), 0.10 g (0.44 mmol) of 2,4-diphenyl-4-methyl-1-pentene as a chain transfer agent, and a solvent. 15 ml of N-methyl-2-pyrrolidone (NMP) was added thereto, 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 desired polymer (P-1). The weight average molecular weight Mw measured in terms of polystyrene by GPC was 30,000, and the molecular weight distribution Mw/Mn was 2.8.

[Synthesis Examples 2-2 to 2-5, 2-7 and 2-8]
Polymers (P-2) to (P-5), (P-7), and (P-8) were each synthesized. In Table 1, the numerical unit of the monomer composition is "mole part".

[Synthesis example 2-6]
In a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, and a reflux condenser, 40 mole parts of compound (MA-7) and 20 mole parts of compound (MS-1) were added to 100 mole parts of the total amount of monomers. , and Compound (MS-2) were charged in an amount of 40 mol, and further, 50 g of methyl isobutyl ketone and 5 g of triethylamine were charged and mixed at room temperature. Next, 35 g of deionized water was added dropwise from the dropping funnel over 30 minutes, and the mixture was reacted at 80° C. for 6 hours while being mixed under reflux. After the reaction, the organic layer was taken out and washed with a 0.2% by mass ammonium nitrate aqueous solution until the water after washing became neutral, and then the solvent and water were distilled off under reduced pressure to remove the heavy polyorganosiloxane. The combined product (P-6) was obtained as 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 are dissolved in N-methyl-2-pyrrolidone (NMP). By reacting at 40° C. for 3 hours, a solution containing 10% by mass of a polyamic acid polymer (P-9) was obtained.
[Synthesis example 2-10]
100 moles of 2,3,5-tricarboxycyclopentyl acetic dianhydride, 20 moles of 3,5-diaminobenzoic acid, and 80 moles of 2,2'-dimethyl-4,4'-diaminobiphenyl were dissolved in NMP. By reacting at 40° C. for 3 hours, a solution containing 10% by mass of a polyamic acid polymer (P-10) was obtained.

[Synthesis example 2-11]
According to the procedure of Production Example 2 described in Korean Patent Publication No. 2015-138548, a maleimide resin having a chalcone side chain (this will be referred to as "polymer (P-11)") was synthesized.
[Synthesis example 2-12]
According to the procedure of Example 1 described in Japanese Patent No. 2962473, a maleimide resin having a cinnamoyl group in its side chain (this will be referred to as "polymer (P-12)") was synthesized.
[Synthesis example 2-13]
A styrene resin having a cinnamoyl group in its side chain (this will be referred to as "polymer (P-13)") was synthesized according to the procedure of Production Example 1 described in JP-A-2015-152743.
[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-butoxy) Polyamic acid (this will be referred to as "polymer (P-14)") was synthesized using phenyl)-1,3-dioxoisoindolin-5-yl) acrylate.

<Manufacture and evaluation of liquid crystal display devices>
[Example 1]
(1) Preparation of liquid crystal alignment agent Cyclopentanone (CPN) and butyl cellosolve (BC) were added as a solvent to a container containing 100 parts by mass of the polymer (P-1) obtained in Synthesis Example 2-1, and the solvent composition was The solution was CPN/BC=70/30 (mass ratio) and solid content concentration was 3.5% by mass. A liquid crystal aligning agent (AL-1) was prepared by filtering this solution through a filter with a pore size of 1 μm.

(2) Manufacture of optical vertical type liquid crystal display element The liquid crystal aligning agent (AL-1) prepared in the above (1) was coated on the transparent electrode surface of the glass substrate with transparent electrode made of ITO film using a spinner, and the temperature was increased to 80°C. Prebaking was performed on a hot plate for 1 minute to form a coating film with a thickness of 0.08 μm. Next, the surface of this coating film was irradiated with 200 J/m ² of polarized ultraviolet light including a 313 nm bright line at room temperature from a direction inclined at 40° from the normal line of the substrate using an Hg-Xe lamp and a Glan-Taylor prism. Next, the film was heated at 160° C. for 40 minutes (main baking) in an oven whose interior was replaced with nitrogen to obtain a liquid crystal alignment film. The same operation was repeated to create a pair (two substrates) on which a liquid crystal alignment film was formed.
After applying an epoxy resin adhesive containing aluminum oxide spheres with a diameter of 3.5 μm to the outer periphery of the surface with the liquid crystal alignment film on one of the two substrates on which the liquid crystal alignment film was formed, a pair of A pair of substrates were pressed together so that the liquid crystal alignment film surfaces of the substrates faced each other and the optical axes of the ultraviolet rays irradiated onto each substrate were antiparallel to each other, and the adhesive was applied at 150°C for 1 hour. Heat cured. Next, a nematic liquid crystal (MLC-6608, manufactured by Merck & Co., Ltd.) was filled into the gap between the substrates through a liquid crystal injection port, and then the liquid crystal injection port was sealed with an epoxy adhesive to obtain a liquid crystal cell. Further, in order to eliminate fluid orientation during liquid crystal injection, the liquid crystal cell was heated at 150° C. and then slowly cooled to room temperature. Next, polarizing plates are placed on both outer sides of the substrate in the liquid crystal cell, with their polarization directions perpendicular to each other and at an angle of 45° with the projection direction of the optical axis of the ultraviolet rays irradiated upon forming the liquid crystal alignment film onto the substrate surface. I pasted them together to form an eggplant.

(3) Evaluation of pretilt angle The liquid crystal display element manufactured in (2) above was evaluated according to the method described in the non-patent document (TJ Scheffer et. al. J. Appl. Phys. vo. 19. p2013 (1980)). The value of the tilt angle of the liquid crystal molecules from the substrate surface measured by the crystal rotation method using He--Ne laser light was defined as the pretilt angle. At this time, when the pretilt angle was less than 89.0°, it was evaluated as "good (○)", and when it was 89.0° or more, it was evaluated as "poor (x)". As a result, in this example, the pretilt angle was evaluated as "good" (○).

(4) Evaluation of coating uniformity The liquid crystal aligning agent (AL-1) prepared in (1) above was applied onto a glass substrate using a spinner, and after pre-baking on a hot plate at 80°C for 1 minute, A coating film having an average thickness of 0.1 μm was formed by heating (post-baking) for 1 hour in a 200° C. oven with nitrogen purging inside the chamber. The surface of the obtained coating film was observed with an atomic force microscope (AFM), and the uniformity of the coating film surface was evaluated by measuring the center average roughness (Ra). The coating uniformity was evaluated as "good (○)" when Ra was 5 nm or less, "fair (Δ)" when it was greater than 5 nm and less than 10 nm, and "poor (x)" when it was 10 nm or more. As a result, this example was evaluated as "fair (△)".

(5) Evaluation of pretilt angle variation characteristics (post-bake margin) with respect to differences in post-bake temperature Liquid crystal alignment films were prepared using different post-bake temperatures (150°C and 200°C) according to the method (2) above. The pretilt angles of the two liquid crystal display elements were measured. Difference Δθ between the measured value θ200 of the pretilt angle of the liquid crystal display element at a post-bake temperature of 200°C and the measured value θ150 of the pretilt angle of the liquid crystal display element at the post-bake temperature of 150°C (= | θ200 - θ150 |) We evaluated the variation characteristics of the pretilt angle with respect to the difference in post-bake temperature. It can be said that the smaller Δθ is, the smaller the variation in the pretilt angle with respect to the difference in prebake temperature is, and the better. The pretilt angle was measured by the method described in "(3) Pretilt angle evaluation" above. The evaluation is "Excellent (◎)" when Δθ is 0.1° or less, "Good (○)" when Δθ is greater than 0.1° and 0.2°, and 0. A case where the angle was greater than 2° and less than 0.5° was rated as “fair (△)”, and a case where it was 0.5° or more was rated as “poor” (x). As a result, this example was evaluated as "fair (△)".

[Examples 2 to 10, Comparative Examples 1 to 4]
A liquid crystal aligning agent was prepared in the same manner as in Example 1 except that the formulation of the liquid crystal aligning agent was changed as shown in Table 2 below. Further, using each of the prepared liquid crystal aligning agents, optical vertical type liquid crystal display elements were manufactured in the same manner as in Example 1, and various evaluations were performed in the same manner as in Example 1. The results are shown in Table 2 below. Note that in Examples 3 to 10 and Comparative Examples 1 to 4, two types of polymers were blended. In Example 10, an additive (photosensitizer) was blended with the liquid crystal aligning agent.

In Table 2, the numerical values in parentheses in the column of polymer components and additives indicate the blending ratio (unit: parts by mass) of each compound of the polymer components and additives used for preparing the liquid crystal aligning agent. The numerical value in the solvent column indicates the blending ratio (mass ratio) of each solvent with respect to the total amount of the solvent used for preparing the liquid crystal aligning agent. 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 aligning agent contained polymer (A), the pretilt angle was less than 89 degrees, and in Comparative Examples 1 to 4, which did not contain polymer (A), the pretilt angle was less than 89 degrees. In comparison, the angle of inclination of the liquid crystal molecules from the vertical direction could be made sufficiently large. Further, in Examples 1 to 10, variations in pretilt angle due to differences in post-bake temperature were small. In particular, in Examples 8 and 9, in which a polymer with a photosensitizing structure was blended, and in Example 10, in which an additive with a photosensitizing structure was blended, the post-bake margin was evaluated as "excellent", and was particularly excellent. Ta. Furthermore, the liquid crystal aligning agents of Examples 1 to 10 had good coating uniformity. Furthermore, it has been found that by using an open ring monomer (R1), coating uniformity can be improved.
From these results, it was found that by using the polymer (A), it was possible to form a liquid crystal alignment film with good coating uniformity and excellent pretilt angle characteristics.

Claims (8)

Containing a polymer (A) 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), Liquid crystal alignment agent.

(In formula (1) and formula (2), one of R ^{1 and} R ² is a monovalent group having a polymerizable group, and ^the other is a hydrogen atom or a monovalent organic group. or represents a ring structure formed by combining R ¹ and R ² together with the nitrogen atom to which R ¹ and R ² are bonded.However, the ring structure does not contain a polymerizable carbon-carbon unsaturated bond. ( ^A1 is a monovalent organic 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.) The liquid crystal aligning agent according to claim ^{1, wherein the A 1} is a monovalent group having a photoalignable group. The liquid crystal aligning agent according to claim 1 or 2, further comprising a polymer (B) which is at least one type selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, and polyurea. The polymer (A) according to any one of claims 1 to 3, has a structural unit derived from a monomer having at least one selected from the group consisting of a cyclic ether structure and a cyclic carbonate structure. Liquid crystal alignment agent. The liquid crystal according to any one of claims 1 to 4, wherein the polymer (A) has a structural unit derived from a monomer having at least one selected from the group consisting of a carboxyl group and a protected carboxyl group. Orienting agent. According to any one of claims 1 to 5, the polymer (A) or additive component contains a compound having a partial structure capable of exhibiting a photosensitizing function that exhibits a sensitizing effect upon irradiation with light. Liquid crystal alignment agent. A liquid crystal aligning film formed using the liquid crystal aligning agent according to any one of claims 1 to 6. A liquid crystal element comprising the liquid crystal alignment film according to claim 7.