JP2022031136A - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal element - Google Patents

Abstract

To provide a liquid crystal alignment agent with which a liquid crystal element superior in liquid crystal alignment and a voltage holding rate can be obtained.SOLUTION: There is provided a liquid crystal alignment agent which includes a polymer (P) having at least one kind selected from a group consisting of a partial structure represented by a formula (1) and a partial structure represented by a formula (2). In the formulas, X1 is a tetravalent organic group. X2 is a divalent organic group represented by a formula (3). At least one of A1 and A2 is a divalent heterocyclic aromatic group having a nitrogen atom. Y1 and Y2 are "-NR4-" etc. R3 is a divalent organic group obtained by substituting -NR5CO- etc., for at least one arbitrary methylene group of a C2-20 divalent saturated aliphatic hydrocarbon group.SELECTED DRAWING: None

Description

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

Liquid crystal elements are widely used in televisions, mobile devices, various monitors, and the like. With such versatility, the liquid crystal element is required to have higher quality, and along with the improvement of the drive method and the element structure, the improvement of the liquid crystal alignment film, which is one of the constituent materials of the liquid crystal element, is being promoted. (For example, see Patent Document 1).

In Patent Document 1, a diamine compound containing a nitrogen-containing diamine such as N, N'-bis (2-((5-aminopyridine-2-yl) amino) ethyl) urea is reacted with a tetracarboxylic acid dianhydride. It is disclosed that the photoreactivity, rubbing resistance, liquid crystal orientation, AC afterimage characteristics, and voltage retention of the coating film are improved in a well-balanced manner by containing the polyamic acid thus obtained in the liquid crystal alignment agent.

Japanese Unexamined Patent Publication No. 2018-200439

As a liquid crystal element, further improvement of liquid crystal orientation and voltage retention is required in order to meet the demand for higher definition in recent years.

The present invention has been made in view of the above problems, and one object of the present invention is to provide a liquid crystal alignment agent capable of obtaining a liquid crystal element having good liquid crystal orientation and voltage retention.

The present invention employs the following means to solve the above problems.

（式（１）及び式（２）中、Ｘ^１は４価の有機基である。Ｘ^２は、下記式（３）で表される２価の有機基である。Ｒ^１及びＲ^２は、それぞれ独立して、水素原子又は炭素数１～６の１価の有機基である。）

（式（３）中、Ａ^１及びＡ^２は、それぞれ独立して、２価の芳香族基である。ただし、Ａ^１及びＡ^２のうち少なくとも一方は、窒素原子を有する２価の複素環式芳香族基である。
Ｙ^１及びＹ^２は、それぞれ独立して、単結合、「－Ｏ－」、「－Ｓ－」、「－ＮＲ^４－」、「－ＣＯＯ－」、「－ＮＲ^４－ＣＯ－」、又は含窒素非芳香族複素環を有する２価の基である。
Ｒ^３は、炭素数２～２０の２価の飽和脂肪族炭化水素基における少なくとも１個の任意のメチレン基が、「－Ｏ－」、「－Ｓ－」、及び下記式（４）～式（１０）

のそれぞれで表される基のうち少なくとも一種に置き換えられてなる２価の有機基である。ただし、Ｒ^３は、上記式（４）～式（１０）のそれぞれで表される基のうち少なくとも一種を合計１個以上含む。Ｒ^３において、「－Ｏ－」、「－Ｓ－」及び上記式（４）～式（１０）で表される基は互いに隣接しておらず、かつ「－Ｏ－」、「－Ｓ－」及び上記式（４）～式（１０）で表される基の２個の結合手は、炭化水素基、含窒素非芳香族複素環又は含窒素芳香族複素環を構成する炭素原子にそれぞれ結合している。
Ｒ^４及びＲ^５は、それぞれ独立して、水素原子若しくは１価の有機基であるか、又はＲ^４とＲ^５とが互いに合わせられて、Ｒ^４が結合する窒素原子及びＲ^５が結合する窒素原子と共に構成される環構造を表す。Ｒ^６、Ｒ^７及びＲ^８は、それぞれ独立して、水素原子又は１価の有機基である。
ただし、Ｒ^３が上記式（５）～式（７）で表される２価の基のうちのいずれかを含む場合、Ｙ^１、Ｙ^２及びＲ^３のうち少なくともいずれかは極性官能基の保護基を有する。
Ａ^３は、窒素原子を有する２価の複素環式芳香族基である。「＊」は結合手を示す。） <1> A liquid crystal alignment agent containing a polymer (P) having at least one selected from the group consisting of a partial structure represented by the following formula (1) and a partial structure represented by the following formula (2).

(In the formulas (1) and (2), X ¹ is a tetravalent organic group. X ² is a divalent organic group represented by the following formula (3). R ¹ and R ² are. , Each independently is a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms.)

(In the formula (3), A ¹ and A ² are independently divalent aromatic groups, respectively. However, at least one of A ¹ and A ² is a divalent heterocycle having a nitrogen atom. It is a formula aromatic group.
Y ¹ and Y ² are independently single-bonded, "-O-", "-S-", "-NR ^4- ", "-COO-", "-NR ⁴ -CO-", or It is a divalent group having a nitrogen-containing non-aromatic heterocycle.
In R3 ^, at least one arbitrary methylene group in the divalent saturated aliphatic hydrocarbon group having 2 to 20 carbon atoms is "-O-", "-S-", and the following formulas (4) to (4) to formulas. (10)

It is a divalent organic group that is replaced with at least one of the groups represented by each of the above. However, R ³ contains at least one group in total among the groups represented by each of the above formulas (4) to (10). In R3 ^, the groups represented by "-O-", "-S-" and the above formulas (4) to (10) are not adjacent to each other, and "-O-", "-S-". And the two bonds of the groups represented by the above formulas (4) to (10) are attached to the carbon atoms constituting the hydrocarbon group, the nitrogen-containing non-aromatic heterocycle or the nitrogen-containing aromatic heterocycle, respectively. It is combined.
R ⁴ and R ⁵ are independently hydrogen atoms or monovalent organic groups, or R ⁴ and R ⁵ are combined with each other, and the nitrogen atom to which R ⁴ is bonded and R ⁵ are bonded. Represents a ring structure composed of nitrogen atoms. R ⁶ , R ⁷ and R ⁸ are independently hydrogen atoms or monovalent organic groups.
However, when R ³ contains any of the divalent groups represented by the above formulas (5) to (7), at least one of Y ¹ , Y ² and R ³ is a polar functional group. It has a protecting group.
A ³ is a divalent heterocyclic aromatic group having a nitrogen atom. "*" Indicates a bond. )

（式（２２）中、Ａ^１、Ａ^２、Ｙ^１、Ｙ^２及びＲ^３は上記式（３）と同義である。） <2> A liquid crystal alignment film formed by using the liquid crystal alignment agent of <1> above.
<3> A liquid crystal element provided with the liquid crystal alignment film of <2> above.
<4> A polymer having at least one selected from the group consisting of the partial structure represented by the above formula (1) and the partial structure represented by the above formula (2).
<5> A compound represented by the following formula (22).

(In the formula (22), A ¹ , A ² , Y ¹ , Y ² and R ³ are synonymous with the above formula (3)).

According to the liquid crystal alignment agent of the present invention, it is possible to obtain a liquid crystal element having good liquid crystal orientation and voltage retention. In particular, even when the liquid crystal element is driven for a long time, it is possible to obtain a liquid crystal element that is less likely to generate an AC afterimage and can maintain a high voltage retention rate.

Hereinafter, each component contained in the liquid crystal alignment agent of the present disclosure, and other components optionally blended will be described.

In addition, in this specification, a "hydrocarbon group" means a chain hydrocarbon group, an alicyclic hydrocarbon group and an aromatic hydrocarbon group. The "chain hydrocarbon group" means a linear hydrocarbon group and a branched hydrocarbon group which 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. The "alicyclic hydrocarbon group" means a hydrocarbon group containing only the alicyclic hydrocarbon structure as the ring structure and not containing the aromatic ring structure. However, it does not have to be composed only of the alicyclic hydrocarbon structure, and some of them have a chain structure. The "aromatic hydrocarbon group" means a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it does not have to be composed only of an aromatic ring structure, and may include a chain structure or an alicyclic hydrocarbon structure as a part thereof.

The "saturated aliphatic hydrocarbon group" means to include a saturated chain hydrocarbon group and a saturated alicyclic hydrocarbon group. The "aromatic group" means a group obtained by removing n hydrogen atoms (n is an integer) from the ring portion of a substituted or unsubstituted aromatic hydrocarbon ring or a substituted or unsubstituted aromatic heterocycle. do. However, when the aromatic group has a plurality of rings, it includes a group obtained by removing n hydrogen atoms from the same ring and a group obtained by removing n hydrogen atoms from different rings. The "heterocyclic aromatic group" means a group obtained by removing n hydrogen atoms (n is an integer) from the ring portion of the aromatic heterocycle. However, when the heterocyclic aromatic group has a plurality of rings, it includes a group obtained by removing n hydrogen atoms from the same ring and a group obtained by removing n hydrogen atoms from different rings. The "protecting group" refers to an atomic group that temporarily converts a highly reactive characteristic group into an inactive functional group.

（式（１）及び式（２）中、Ｘ^１は４価の有機基である。Ｘ^２は、下記式（３）で表される２価の有機基である。Ｒ^１及びＲ^２は、それぞれ独立して、水素原子又は炭素数１～６の１価の有機基である。）

（式（３）中、Ａ^１及びＡ^２は、それぞれ独立して、２価の芳香族基である。ただし、Ａ^１及びＡ^２のうち少なくとも一方は、窒素原子を有する２価の複素環式芳香族基である。
Ｙ^１及びＹ^２は、それぞれ独立して、単結合、「－Ｏ－」、「－Ｓ－」、「－ＮＲ^４－」、「－ＣＯＯ－」、「－ＮＲ^４－ＣＯ－」、又は含窒素非芳香族複素環を有する２価の基である。
Ｒ^３は、炭素数２～２０の２価の飽和脂肪族炭化水素基における少なくとも１個の任意のメチレン基が、「－Ｏ－」、「－Ｓ－」、及び下記式（４）～式（１０）

のそれぞれで表される基のうち少なくとも一種に置き換えられてなる２価の有機基である。ただし、Ｒ^３は、上記式（４）～式（１０）のそれぞれで表される基のうち少なくとも一種を合計１個以上含む。Ｒ^３において、「－Ｏ－」、「－Ｓ－」及び上記式（４）～式（１０）で表される基は互いに隣接しておらず、かつ「－Ｏ－」、「－Ｓ－」及び上記式（４）～式（１０）で表される基の２個の結合手は、炭化水素基、含窒素非芳香族複素環又は含窒素芳香族複素環を構成する炭素原子にそれぞれ結合している。Ｒ^４及びＲ^５は、それぞれ独立して、水素原子若しくは１価の有機基であるか、又はＲ^４とＲ^５とが互いに合わせられて、Ｒ^４が結合する窒素原子及びＲ^５が結合する窒素原子と共に構成される環構造を表す。Ｒ^６、Ｒ^７及びＲ^８は、それぞれ独立して、水素原子又は１価の有機基である。ただし、Ｒ^３が上記式（５）～式（７）で表される２価の基のうちのいずれかを含む場合、Ｙ^１、Ｙ^２及びＲ^３のうち少なくともいずれかは極性官能基の保護基を有する。Ａ^３は、窒素原子を有する２価の複素環式芳香族基である。「＊」は結合手を示す。） The liquid crystal alignment agent of the present disclosure contains a polymer (P) having at least one selected from the group consisting of a partial structure represented by the following formula (1) and a partial structure represented by the following formula (2).

(In the formulas (1) and (2), X ¹ is a tetravalent organic group. X ² is a divalent organic group represented by the following formula (3). R ¹ and R ² are. , Each independently is a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms.)

(In the formula (3), A ¹ and A ² are independently divalent aromatic groups, respectively. However, at least one of A ¹ and A ² is a divalent heterocycle having a nitrogen atom. It is a formula aromatic group.
Y ¹ and Y ² are independently single-bonded, "-O-", "-S-", "-NR ^4- ", "-COO-", "-NR ⁴ -CO-", or It is a divalent group having a nitrogen-containing non-aromatic heterocycle.
In R3 ^, at least one arbitrary methylene group in the divalent saturated aliphatic hydrocarbon group having 2 to 20 carbon atoms is "-O-", "-S-", and the following formulas (4) to (4) to formulas. (10)

It is a divalent organic group that is replaced with at least one of the groups represented by each of the above. However, R ³ contains at least one group in total among the groups represented by each of the above formulas (4) to (10). In R3 ^, the groups represented by "-O-", "-S-" and the above formulas (4) to (10) are not adjacent to each other, and "-O-", "-S-". And the two bonds of the groups represented by the above formulas (4) to (10) are attached to the carbon atoms constituting the hydrocarbon group, the nitrogen-containing non-aromatic heterocycle or the nitrogen-containing aromatic heterocycle, respectively. It is combined. R ⁴ and R ⁵ are independently hydrogen atoms or monovalent organic groups, or R ⁴ and R ⁵ are combined with each other, and the nitrogen atom to which R ⁴ is bonded and R ⁵ are bonded. Represents a ring structure composed of nitrogen atoms. R ⁶ , R ⁷ and R ⁸ are independently hydrogen atoms or monovalent organic groups. However, when R ³ contains any of the divalent groups represented by the above formulas (5) to (7), at least one of Y ¹ , Y ² and R ³ is a polar functional group. It has a protecting group. A ³ is a divalent heterocyclic aromatic group having a nitrogen atom. "*" Indicates a bond. )

In the above formulas (1) and (2), X ¹ is a tetravalent organic group derived from a tetracarboxylic acid derivative. In addition, in this specification, "tetracarboxylic acid derivative" means containing tetracarboxylic acid dianhydride, tetracarboxylic acid diester and tetracarboxylic acid diester dihalide.

（式（１４）～（２１）中、「＊」は結合手を示す。） As the tetracarboxylic acid derivative constituting X ¹ , a compound known as a tetracarboxylic acid derivative that can be used in the production of polyamic acid, polyamic acid ester and polyimide can be used. From the viewpoint of easy availability of the compound, easy production of the polymer, and the like, X ¹ is preferably a tetravalent group represented by any of the following formulas (14) to (21). When a liquid crystal alignment film is obtained by a photoalignment method, X ¹ is preferably a tetravalent group having a cyclobutane ring structure, and specifically, a tetravalence represented by the following formula (14) or formula (15). It is particularly preferable that it is the basis of.

(In equations (14) to (21), "*" indicates a bond.)

In the above formulas (1) and (2), X ² is a divalent organic group derived from a diamine compound having a partial structure represented by the above formula (3) (hereinafter, also referred to as "specific diamine"). be. In the above formula (3), at least one of A ¹ and A ² is a divalent heterocyclic aromatic group having a nitrogen atom. Examples of the divalent heterocyclic aromatic group having a nitrogen atom include a pyrrole ring, a pyrazole ring, an imidazole ring, a triazole ring, an oxazole ring, a thiazole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, and a triazine ring. , Indole ring, benzimidazole ring, benzoxazole ring, benzothiazole ring, purine ring, quinoline ring, carbazole ring, bipyridine ring and other divalent groups having a nitrogen-containing aromatic heterocycle. In the heterocyclic aromatic groups of A ¹ and A ² , a substituent may be introduced into the nitrogen-containing aromatic heterocycle. Examples of the substituent include an alkyl group having 1 to 6 carbon atoms, a protecting group, and a hydroxy group.

When only one of A ¹ and A ² is a divalent heterocyclic aromatic group having a nitrogen atom, specific examples of the other group include, for example, a benzene ring, a naphthalene ring, a biphenyl ring, and a furan ring. Examples thereof include divalent groups having an aromatic hydrocarbon ring or an aromatic heterocycle such as a thiophene ring, a benzofuran ring, a benzothiophene ring, and a fluorene ring.
Of the above, A ¹ and A ² are preferably a divalent group having a benzene ring or a pyridine ring, and more preferably a phenylene group, a pyridylene group, a biphenylene group or a bipyridylene group. Further, from the viewpoint of electrical characteristics, a basic structure is preferable, a divalent group having a pyridine ring, an imidazole ring or a benzimidazole ring is more preferable, a divalent group having a pyridine ring is further preferable, and a pyridylene group is more preferable. Especially preferable.

Y ¹ and Y ² are independently single bonds, "-O-", "-S-", "-NR ^4- ", "-COO-" or "-NR ⁴ -CO-", respectively. Or, it is a divalent group having a nitrogen-containing non-aromatic heterocycle. In Y ¹ and Y ² , the divalent groups having a nitrogen-containing non-aromatic heterocycle include piperidine-1,4-diyl group, piperazine-1,4-diyl group, and -CO-B ^1- (however, however. Examples of B ¹ include piperidine-1,4-diyl group or piperazine-1,4-diyl group).
Y ¹ and Y ² are adjacent aromatic groups (Y) from the viewpoint of enhancing the photoreactivity of the polymer (P) when X ¹ in the above formulas (1) and (2) has a cyclobutane ring structure. An electron donating group that increases the electron density of ¹ , Y ² ) is preferable, and an "-O-", "-S-", "-NR ^4- " or piperidine-1,4-diyl group is more preferable. , "-NR ^4- " or "-O-" is more preferable.

R ⁴ in "-NR ^4- " is a hydrogen atom or a monovalent organic group, or is combined with R ⁵ in the above formulas (4) to (7), and R ⁴ is bonded. It constitutes a ring structure together with the nitrogen atom to which it is bonded and the nitrogen atom to which ^R5 is bonded. Examples of the ring structure include piperazine-1,4-diyl groups and the like.
From the viewpoint of enhancing the solubility of the polymer (P), ^R4 is preferably a protecting group or a monovalent saturated aliphatic hydrocarbon group having 1 to 6 carbon atoms, and is preferably a protecting group or a monovalent saturated aliphatic hydrocarbon group having 1 to 3 carbon atoms. It is preferably an alkyl group, more preferably a protecting group.

When R ⁴ is a protecting group, the protecting group is preferably a desorbing group that is desorbed by at least one of heat and light, and more preferably a thermal desorbing group. When R ⁴ is a thermally desorbable group, the protecting group can be desorbed in the process of applying the liquid crystal alignment agent to the substrate and heating to form the liquid crystal alignment film. Therefore, it is not necessary to separately provide a process for deprotection, which is preferable in that the process can be simplified. From the viewpoint of deprotection in the process of forming the liquid crystal alignment film, the thermally desorbing group is particularly preferably a group that decomposes at a temperature of 120 to 300 ° C. and replaces a hydrogen atom.

In R3 ^, at least one arbitrary methylene group in the divalent saturated aliphatic hydrocarbon group having 2 to 20 carbon atoms is "-O-", "-S-" and the above formulas (4) to (4). It is a divalent organic group that is replaced with at least one of the groups represented by each of 10). In R3 ^, the divalent aliphatic hydrocarbon group is preferably a monovalent chain hydrocarbon group, more preferably an alkylene group having 2 to 12 carbon atoms, from the viewpoint of the liquid crystal orientation of the polymer (P). , An alkylene group having 4 to 12 carbon atoms is more preferable, and an alkylene group having 4 to 8 carbon atoms is particularly preferable.

R ³ contains at least one of the groups represented by each of the above formulas (4) to (10) (hereinafter, also referred to as “specific nitrogen-containing group”) in total of one or more. Here, with respect to A3 in the above formulas (8) to (10) ^, specific examples of the divalent heterocyclic aromatic group having ^a nitrogen atom include the groups exemplified in the description of A1 and ^A2 . Can be mentioned. Of these, A3 has a pyridine ring ^, a pyrimidine ring, a triazine ring, an imidazole ring, a benzimidazole ring or a purine ring from the viewpoint of electrical and mechanical properties, and is a divalent ring that forms a hydrogen bond between molecules. The group is preferred. Among these, a divalent group having a pyridine ring is more preferable, and a pyridylene group is particularly preferable, from the viewpoint of ease of synthesis and electrical properties. ^In addition, A3 may have a substituent in the heterocyclic portion. Examples of the substituent include an alkyl group having 1 to 5 carbon atoms, a hydroxy group and the like.

From the viewpoint of the solubility of the polymer (P), the specific nitrogen-containing group contained in R ³ may be a group represented by any of the above formulas (4) and (8) to (10). preferable. Further, from the viewpoint of the electrical characteristics of the polymer (P), the specific nitrogen-containing group contained in R ³ is preferably a group represented by any of the above formulas (4) to (7). The number of specific nitrogen-containing groups possessed by R ³ is not particularly limited, and can be appropriately set according to the type of the specific nitrogen-containing group and the like. For example, when the specific nitrogen-containing group contained in R ³ is a group represented by the above formula (4), the number of the specific nitrogen-containing groups is preferably 2 or more, and more preferably 2 or 3. When the specific nitrogen-containing group contained in R ³ is a group represented by any of the above formulas (5) to (10), the number of specific nitrogen-containing groups is preferably one.

Since R ³ has the above structure, when the liquid crystal alignment film is formed by the rubbing method, it is possible to promote the extension of the molecular chain of the polymer (P) in the rubbing treatment. Further, when the liquid crystal alignment film is formed by the photo-alignment method, thermal rearrangement (self-organizing anisotropic amplification) of the molecular chains of the polymer (P) in the heat treatment after exposure can be promoted. This makes it possible to obtain a liquid crystal alignment film having excellent liquid crystal alignment. Further, the specific nitrogen-containing group of R ³ forms a hydrogen bond between the molecules, so that a liquid crystal alignment film having excellent mechanical properties and electrical properties can be obtained. In the above formula R3 ^, both of the two bonds in the specific nitrogen-containing group are bonded to the carbon atom constituting the hydrocarbon group , the nitrogen-containing non-aromatic heterocycle or the nitrogen-containing aromatic heterocycle. .. That is, the two bonds of the specific nitrogen-containing group of R ³ are bonded only to the carbon atoms constituting the hydrocarbon group, the nitrogen-containing non-aromatic heterocycle or the nitrogen-containing aromatic heterocycle.

The monovalent organic group in R ⁵ , R ⁶ , R ⁷ and R ⁸ is a protecting group or a monovalent saturated aliphatic hydrocarbon group having 1 to 6 carbon atoms from the viewpoint of enhancing the solubility of the polymer (P). It is preferably a protecting group or an alkyl group having 1 to 3 carbon atoms, and more preferably a protecting group. The description of the protecting group can be referred to the description of the protecting group in ^R4 above.

X ² preferably has a polar functional group protecting group. The protecting group of the polar functional group of X ² can be a protecting group such as an amino group, a hydroxy group and a carboxy group. The protecting group is preferably a desorbable group that is desorbed by at least one of heat and light, and more preferably a thermal desorbable group. From the viewpoint of deprotecting in the process of forming the liquid crystal alignment film, it is particularly preferable that the protecting group of the polar functional group of X ² is a group that decomposes at a temperature of 120 to 300 ° C. and replaces a hydrogen atom.

From the viewpoint of enhancing electrical properties, X ² is a polar functional group for inactivating at least one selected from the group consisting of an amino group, an amide group, a urea bond, an oxalyldiamide bond and a diacylhydrazide bond. It is preferable to have it as a protecting group. For example, when X ² contains an amino-protecting group, the desorption reaction generates a basic primary or secondary amine to promote the imidization reaction of polyamic acid, and to remove acidic impurities present in the liquid crystal. Capturing, forming non-covalent bridges between molecules, etc. are envisioned.

When X ² has a polar functional group protecting group, any one of A ¹ , A ² , Y ¹ , Y ² and R ³ may have a polar functional group protecting group, and in X ² The number of protecting groups in the above is also not particularly limited. However, when R ³ contains any of the divalent groups represented by the above formulas (5) to (7), at least one of Y ¹ , Y ² and R ³ is a protecting group for polar functional groups. , And preferably at least one of ^R4 to ^R8 is a protecting group.
From the viewpoint of increasing the solubility of the polymer (P) in the state of the liquid crystal alignment agent and enhancing the electrical properties after the formation of the liquid crystal alignment film, X ² may have two or more protecting groups of polar functional groups. preferable. ^In X2, the number of protecting groups of the polar functional group is preferably 4 or less from the viewpoint of ease of production of the polymer (P) and the mechanical properties of the liquid crystal alignment film.

Specific examples of the thermally desorbing group include a methoxycarbonyl group, a trifluoromethoxycarbonyl group, an ethoxycarbonyl group, an n-propoxycarbonyl group, an isopropoxycarbonyl group, an n-butoxycarbonyl group, a tert-butoxycarbonyl group, and sec-. Examples thereof include a butoxycarbonyl group, an n-pentyloxycarbonyl group, an n-hexyloxycarbonyl group, a 9-fluorenylmethoxycarbonyl group and the like. Of these, a structure in which the desorption reaction proceeds efficiently at the firing temperature (preferably 120 to 300 ° C.) of the liquid crystal alignment film is preferable, and a tert-butoxycarbonyl group or a 9-fluorenylmethoxycarbonyl group is more preferable. A tert-butoxycarbonyl group (Boc group) is particularly preferred.

（式（１１）～式（１３）中、Ｙ^３及びＹ^４は、それぞれ独立して「＊^１－ＮＲ^９－ＣＯ－」又は「－ＮＲ^９－ＣＯ－＊^１」である。「＊^１」は、「－（ＣＨ_２）_ｒ－」との結合手を示す。Ｒ^９、Ｒ^１０、Ｒ^１１、Ｒ^１２、Ｒ^１３及びＲ^１４は、それぞれ独立して、水素原子又は１価の有機基である。ただし、式（１２）中、Ｙ^１、Ｙ^２、Ｒ^１０及びＲ^１１のうち少なくともいずれかは極性官能基の保護基を有する。ｒは１～６の整数である。ｓ及びｔは、それぞれ独立して０～６の整数である。ただし、１≦ｒ＋ｓ＋ｔ≦１２を満たす。ｖ、ｗ、ｅ及びｆは、それぞれ独立して１～６の整数である。ｕは０～２の整数である。Ａ^１、Ａ^２、Ｙ^１、及びＹ^２は、上記式（３）と同義である。「＊」は結合手を示す。） X ² is a divalent group formed by appropriately combining the groups exemplified in the above description of A ¹ , A ² , Y ¹ , Y ² and R ³ . X ² is a group represented by the following formula (11), a group represented by the following formula (12), or a group represented by the following formula, in that a liquid crystal element having excellent liquid crystal orientation, electrical characteristics, and mechanical characteristics can be obtained. It is preferably the group represented by (13).

(In equations (11) to (13), Y ³ and Y ⁴ are independently "* ¹ -NR ⁹ -CO-" or "-NR ^{9 -} CO- * ¹ ", respectively. Indicates a bond with "-(CH ₂ ) _r- ". R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are independently hydrogen atoms or monovalent organic substances. However, in formula (12), at least one of Y ¹ , Y ² , R ¹⁰ and R ¹¹ has a protective group for a polar functional group. R is an integer of 1 to 6. S and t is an independently integer of 0 to 6. However, 1 ≦ r + s + t ≦ 12 is satisfied. V, w, e and f are independently integers of 1 to 6. u is 0 to 6. It is an integer of 2. A ¹ , A ² , Y ¹ and Y ² are synonymous with the above equation (3). “*” Indicates a bond.)

In the above formulas (11) to (13), specific examples and preferable examples of the monovalent organic groups of R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are described in the above R ⁴ . Can be used.
The s and t are preferably 1 or more, and preferably 2 or more, from the viewpoint of enhancing the liquid crystal orientation of the liquid crystal element. Further, from the viewpoint of ensuring the electrical characteristics of the liquid crystal element, s and t are preferably 4 or less. r is preferably 1 to 4.

The values of v, w, e and f are preferably 2 or more from the viewpoint of enhancing the liquid crystal orientation of the liquid crystal element, and preferably 4 or less from the viewpoint of ensuring the electrical characteristics of the liquid crystal element.
For A ¹ , A ² , Y ¹ , and Y ² , the description of specific examples and preferable examples of A ¹ , A ² , Y ¹ , and Y ² in the above formula (3) can be incorporated.

（式（１１－１）及び式（１２－１）中、Ｒ^１５、Ｒ^１６、Ｒ^１７及びＲ^１８は、それぞれ独立して、水素原子、炭素数１～６の１価の脂肪族炭化水素基又は熱脱離性基である。ただし、式（１２－１）中、Ｒ^１５、Ｒ^１６、Ｒ^１７及びＲ^１８のうち少なくともいずれかは熱脱離性基である。ｐは１～４の整数である。「＊」は結合手を示す。） In particular, the fact that X ² is a divalent group represented by the following formula (11-1) or a divalent group represented by the following formula (12-1) is the liquid crystal orientation of the liquid crystal element (particularly AC). It is suitable because it has a high effect of reducing afterimages) and improving electrical characteristics (particularly long-term reliability). The AC afterimage is an afterimage caused by the application of an AC voltage, and is an afterimage caused by the initial orientation direction of the liquid crystal being deviated from the direction at the time of manufacture due to the long-time driving of the liquid crystal element.

(In the formula (11-1) and the formula (12-1), R ¹⁵ , R ¹⁶ , R ¹⁷ and R ¹⁸ are independently hydrogen atoms and monovalent aliphatic hydrocarbons having 1 to 6 carbon atoms. It is a group or a thermally desorbing group. However, in the formula ⁽ 12-1), at least one of R15, ^R16 , ^R17 and R18 is a thermally desorbing group. P is ¹ to 4 It is an integer of. "*" Indicates a bond.)

In the above formula (11-1), at least one of R ¹⁵ , R ¹⁶ , R ¹⁷ and R ¹⁸ is thermally desorbable from the viewpoint of solubility, liquid crystal orientation and voltage retention of the polymer (P). It is preferably a group, and more preferably two or more are heat-removable groups. Further, for the same reason, in the above formula (12-1), it is preferable that two or more of R ¹⁵ , R ¹⁶ , R ¹⁷ and R ¹⁸ are thermally desorbing groups.

The polymer (P) is at least one selected from the group consisting of polyamic acid, polyamic acid ester and polyimide. The polymer (P) has a partial structure derived from a tetracarboxylic acid derivative and a partial structure derived from a specific diamine. The method for synthesizing the polymer (P) is not particularly limited, and it can be obtained by appropriately combining conventional methods of organic chemistry.

<Polyamic acid>
When the polymer (P) is a polyamic acid, the polyamic acid (hereinafter, also referred to as “polyamic acid (P)”) reacts, for example, a tetracarboxylic dianhydride with a diamine compound containing a specific diamine. It can be obtained by letting it.

(Tetracarboxylic dianhydride)
The tetracarboxylic dianhydride used for the synthesis of the polyamic acid (P) is not particularly limited, and for example, an aliphatic tetracarboxylic dianhydride, an alicyclic tetracarboxylic dianhydride, and an aromatic tetracarboxylic dianhydride are used. Things etc. can be mentioned.

Specific examples of these include aliphatic tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride and ethylenediaminetetraacetic acid dianhydride;
Examples of the alicyclic tetracarboxylic acid dianhydride include 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,3-dimethylcyclobutane-1,2,3,4-tetracarboxylic acid dianhydride, and the like. 2,3,5-tricarboxycyclopentylactanhydride, 5- (2,5-dioxotetrachloride-3-yl) -3a, 4,5,9b-tetrahydronaphtho [1,2-c] furan-1 , 3-Dione, 5- (2,5-dioxotetrahydride-3-yl) -8-methyl-3a, 4,5,9b-tetrahydronaphtho [1,2-c] furan-1,3-dione, 5- (2,5-dioxotetrahydro-3-franyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornan-2: 3,5: 6-dianhydride, 2,4,6,8-tetracarboxybicyclo [3.3.0] octane-2: 4,6: 8-anhydride, cyclohexanetetracarboxylic acid dianhydride, Cyclopentanetetracarboxylic acid dianhydride, etc.;
Aromatic tetracarboxylic acid dianhydrides include, for example, pyromellitic acid dianhydride, 4,4'-(hexafluoroisopropyridene) diphthalic acid anhydride, p-phenylenebis (trimellitic acid monoester anhydride), ethylene glycol. Bis (anhydrotrimeritate), 1,3-propylene glycol bis (anhydrotrimeritate), 3,3', 4,4'-benzophenone tetracarboxylic acid dianhydride, 4,4'-biphthalic acid dianhydride Anhydrides and the like can be mentioned, and the tetracarboxylic acid dianhydrides described in JP-A-2010-97188 can be used.

Among the above, 1, 2, 3, 4 are the tetracarboxylic acid dianhydrides used in the synthesis of polyamic acid (P) in that the liquid crystal orientation and electrical characteristics can be improved in combination with a specific diamine. -Cyclobutanetetracarboxylic acid dianhydride, 1,3-dimethylcyclobutane-1,2,3,4-tetracarboxylic acid dianhydride, 1,2,3,4-butanetetracarboxylic acid dianhydride, cyclopentanetetra From the group consisting of carboxylic acid dianhydride, cyclohexanetetracarboxylic acid dianhydride, 2,3,5-tricarboxycyclopentylacetichydride dianhydride, pyromellitic acid dianhydride, and 4,4'-biphthalic acid dianhydride. At least one selected compound (hereinafter, also referred to as "specific acid anhydride") is preferable.

When a specific acid anhydride is used in the synthesis of polyamic acid (P), the ratio of the specific acid anhydride used may be 10 mol% or more with respect to the total amount of the tetracarboxylic acid dianhydride used in the synthesis. preferable. It is more preferably 30 mol% or more, further preferably 50 mol% or more, still more preferably 70 mol% or more. In the synthesis of the polymer (P), one type of tetracarboxylic dianhydride may be used alone or two or more types may be used in combination.

（式（２２）中、Ａ^１、Ａ^２、Ｙ^１、Ｙ^２及びＲ^３は、それぞれ、上記式（３）中のＡ^１、Ａ^２、Ｙ^１、Ｙ^２及びＲ^３と同義である。） (Diamine compound)
Examples of the specific diamine include compounds represented by the following formula (22).

(In equation (22), A ¹ , A ² , Y ¹ , Y ² and R ³ are synonymous with A ¹ , A ² , Y ¹ , Y ² and R ³ in the above equation (3), respectively. .)

For specific examples and preferable examples of A ¹ , A ² , Y ¹ , Y ² and R ³ in the above formula (22), the description of the above formula (3) can be incorporated respectively. Specific examples of the specific diamine include compounds represented by the following formulas (d-1) to (d-112).

Among these, the specific diamines include the above formulas (d-1) to (d-3), formulas (d-5), formulas (d-7), and formulas (d-9) to formulas (d-11). ), Formula (d-13) to formula (d-15), formula (d-17), formula (d-19) to formula (d-24), formula (d-27), formula (d-29). -Formula (d-38), Formula (d-41), Formula (d-42), Formula (d-51) -Formula (d-53), Formula (d-55) -Formula (d-60), Compounds represented by the formulas (d-67), (d-77), and formulas (d-107) to (d-112) are preferable, and the above formulas (d-1) to (d-) are preferable. 3), formula (d-5), formula (d-7), formula (d-13) to formula (d-15), formula (d-17), formula (d-22) to formula (d-24). ), Formula (d-51) to formula (d-53), formula (d-55), formula (d-56), and formula (d-107) to formula (d-112). Compounds are particularly preferred. The specific diamine may be used alone or in combination of two or more.

In the synthesis of the polyamic acid (P), only the specific diamine may be used as the diamine compound, but a diamine compound different from the specific diamine (hereinafter, also referred to as “other diamine”) may be used together with the specific diamine. good.

（式（Ｅ－１）中、Ｘ^I及びＸ^IIは、それぞれ独立に、単結合、－Ｏ－、－ＣＯＯ－又は－ＯＣＯ－であり、Ｒ^Ｉは炭素数１～３のアルカンジイル基であり、Ｒ^ＩＩは単結合又は炭素数１～３のアルカンジイル基であり、ａは０又は１であり、ｂは０～２の整数であり、ｃは１～２０の整数であり、ｄは０又は１である。ただし、ａ及びｂが同時に０になることはない。）
で表される化合物等の側鎖型ジアミン：
パラフェニレンジアミン、４，４’－ジアミノジフェニルメタン、４，４’－エチレンジアニリン、４，４’－ジアミノジフェニルアミン、４，４’－ジアミノジフェニルスルフィド、４－アミノフェニル－４’－アミノベンゾエート、４，４’－ジアミノアゾベンゼン、３，５－ジアミノ安息香酸、１，２－ビス（４－アミノフェノキシ）エタン、１，５－ビス（４－アミノフェノキシ）ペンタン、Ｎ，Ｎ’－ジ（４－アミノフェニル）－Ｎ，Ｎ’－ジメチルエチレンジアミン、ビス［２－（４－アミノフェニル）エチル］ヘキサン二酸、ビス（４－アミノフェニル）アミン、Ｎ，Ｎ－ビス（４－アミノフェニル）メチルアミン、１，４－ビス（４－アミノフェニル）－ピペラジン、Ｎ，Ｎ’－ビス（４－アミノフェニル）－ベンジジン、２，２’－ジメチルベンジジン、２，２’－ビス（トリフルオロメチル）－４，４’－ジアミノビフェニル、４，４’－ジアミノジフェニルエーテル、２，２－ビス［４－（４－アミノフェノキシ）フェニル］プロパン、４，４’－（フェニレンジイソプロピリデン）ビスアニリン、１，４－ビス（４－アミノフェノキシ）ベンゼン、４－（４－アミノフェノキシカルボニル）－１－（４－アミノフェニル）ピペリジン、４，４’－［４，４’－プロパン－１，３－ジイルビス（ピペリジン－１，４－ジイル）］ジアニリン等の非側鎖型ジアミンを；
ジアミノオルガノシロキサンとして、例えば、１，３－ビス（３－アミノプロピル）－テトラメチルジシロキサン等を；それぞれ挙げることができるほか、特開２０１０－９７１８８号公報に記載のジアミン化合物を用いることができる。なお、ポリアミック酸（Ｐ）の合成に際し、その他のジアミンとしては、１種を単独で又は２種以上を組み合わせて使用できる。 The other diamine is not particularly limited as long as it is a diamine compound having no group represented by the above formula (3), and examples thereof include aliphatic diamines, alicyclic diamines, aromatic diamines and diaminoorganosiloxanes. .. Specific examples of these include, as aliphatic diamines, for example, metaxylylenediamine, ethylenediamine, 1,3-propanediamine, tetramethylenediamine, hexamethylenediamine and the like;
As the alicyclic diamine, for example, p-cyclohexanediamine, 4,4'-methylenebis (cyclohexylamine) and the like;
Examples of aromatic diamines include dodecanoxidiaminobenzene, hexadecanoxidiaminobenzene, octadecanoxidiaminobenzene, cholestanoloxydiaminobenzene, cholesteryloxydiaminobenzene, cholestanol diaminobenzoate, cholesteryl diaminobenzoate, and diaminobenzoic acid. Ranostanyl, 3,6-bis (4-aminobenzoyloxy) cholesterol, 3,6-bis (4-aminophenoxy) cholesterol, 1,1-bis (4-((aminophenyl) methyl) phenyl) -4-butyl Cyclohexane, 2,5-diamino-N, N-diallylaniline, the following formula (E-1)

(In formula (E-1), X ^I and X ^II are independently single-bonded, -O-, -COO- or ^-OCO- , and RI is an alkanediyl group having 1 to 3 carbon atoms. Yes, R ^II is a single bond or an alkanediyl group with 1 to 3 carbon atoms, a is 0 or 1, b is an integer of 0 to 2, c is an integer of 1 to 20, and d is an integer of 1 to 20. It is 0 or 1. However, a and b cannot be 0 at the same time.)
Side chain diamines such as compounds represented by:
Paraphenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-ethylenedianiline, 4,4'-diaminodiphenylamine, 4,4'-diaminodiphenylsulfide, 4-aminophenyl-4'-aminobenzoate, 4 , 4'-diaminoazobenzene, 3,5-diaminobenzoic acid, 1,2-bis (4-aminophenoxy) ethane, 1,5-bis (4-aminophenoxy) pentane, N, N'-di (4-) Aminophenyl) -N, N'-dimethylethylenediamine, bis [2- (4-aminophenyl) ethyl] hexane diic acid, bis (4-aminophenyl) amine, N, N-bis (4-aminophenyl) methylamine , 1,4-Bis (4-aminophenyl) -piperazine, N, N'-bis (4-aminophenyl) -benzidine, 2,2'-dimethylbenzidine, 2,2'-bis (trifluoromethyl)- 4,4'-Diaminobiphenyl, 4,4'-diaminodiphenyl ether, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 4,4'-(phenylenediisopropyridene) bisaniline, 1,4 -Bis (4-aminophenoxy) benzene, 4- (4-aminophenoxycarbonyl) -1- (4-aminophenyl) piperidine, 4,4'-[4,4'-propane-1,3-diylbis (piperidine) -1,4-diyl)] Non-side chain diamine such as dianiline;
Examples of the diaminoorganosiloxane include 1,3-bis (3-aminopropyl) -tetramethyldisiloxane; and the diamine compound described in JP-A-2010-97188 can be used. .. In synthesizing the polyamic acid (P), as the other diamine, one type may be used alone or two or more types may be used in combination.

From the viewpoint of sufficiently obtaining the effects of the present disclosure, the ratio of the specific diamine used is preferably 10 mol% or more with respect to the total amount of the diamine compounds used in the synthesis of the polyamic acid (P). It is more preferably 20 mol% or more, further preferably 30 mol% or more, still more preferably 40 mol% or more.

The specific diamine can be obtained by appropriately combining the conventional methods of organic chemistry. As an example thereof, a dinitro intermediate having a nitro group instead of the primary amino group in the above formula (21) is synthesized, and then the nitro group of the obtained dinitro intermediate is amination using an appropriate reducing system. How to do it.

The method for synthesizing the dinitro intermediate can be appropriately selected depending on the target compound. For example, an amine compound having the structure "-YA-NO ₂ " (A is A ¹ or R ² and Y is Y ¹ or Y ² ) and a dicarboxylic acid or dicarboxylic acid chloride having the structure R ³ . Method of reacting with; a carboxylic acid having the structure "-YA-NO ₂ " (A is A ¹ or R ² and Y is Y ¹ or Y ² ) and a diamine compound having the structure R ³ . A method of reacting a diamine compound having a structure R ³ with a halogen compound having a structure A; an amine compound having a structure "-YA-NO ₂ " and a bis carbonate (4-nitrophenyl). Methods of reacting; etc. However, the method for synthesizing the specific diamine is not limited to the above.

(Synthesis of polyamic acid)
The polyamic acid (P) can be obtained by reacting a tetracarboxylic dianhydride as described above with a diamine compound, if necessary, with a molecular weight adjusting agent (also referred to as an end-capping agent). Examples of the molecular weight adjusting agent include acid monoanhydrides, monoamine compounds, monoisocyanate compounds and the like. The ratio of the tetracarboxylic acid dianhydride and the diamine compound used in the synthesis reaction of the polyamic acid (P) is the acid anhydride group of the tetracarboxylic acid dianhydride with respect to 1 molar equivalent of the amino group of the diamine compound. Is preferably 0.2 to 2 mol equivalents.

The synthetic reaction of the polyamic acid (P) is preferably carried out in an organic solvent. The reaction temperature at this time is preferably −20 ° C. to 150 ° C., and the reaction time is preferably 0.1 to 24 hours. Examples of the organic solvent used in the reaction include aprotonic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons and the like. Particularly preferred organic solvents are N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide, m-cresol, xylenol. And one or more selected from the group consisting of halogenated phenol is used as a solvent, or one or more of these is mixed with other organic solvents (for example, butyl cellosolve, diethylene glycol diethyl ether, etc.). The amount of the organic solvent used is preferably such that the total amount of the tetracarboxylic dianhydride and the diamine compound is 0.1 to 50% by mass with respect to the total amount of the reaction solution. The reaction solution obtained by dissolving the polyamic acid (P) may be used as it is for the preparation of the liquid crystal alignment agent, or the polyamic acid (P) contained in the reaction solution is isolated and then used for the preparation of the liquid crystal alignment agent. You may.

<Polyamic acid ester>
The polyamic acid ester as the polymer (P) has a structural unit in which at least one of R ¹ and R ² is a monovalent organic group having 1 to 6 carbon atoms in the partial structure represented by the above formula (1). It is a polymer having. The polyamic acid ester is, for example, [I] a method of reacting the polyamic acid (P) obtained above with an esterifying agent (for example, methanol, ethanol, N, N-dimethylformamide diethylacetal, etc.), [II]. The tetracarboxylic acid diester and the diamine compound containing the specific diamine are preferably in an organic solvent with a suitable dehydration catalyst (eg 4- (4,6-dimethoxy-1,3,5-triazine-2-yl) -4. -Method of reacting in the presence of methylmorpholinium halide, carbonyl imidazole, phosphorus-based condensing agent, etc., [III] Tetracarboxylic acid diester dihalide and a diamine compound containing a specific diamine, preferably in an organic solvent, By a method of reacting in the presence of an appropriate base (for example, a tertiary amine such as pyridine or triethylamine, or an alkali metal such as sodium hydride, potassium hydride, sodium hydroxide, potassium hydroxide, sodium or potassium), etc. Obtainable.

The tetracarboxylic dianhydride used in [II] above can be obtained by ring-opening the tetracarboxylic dianhydride with alcohols or the like. The tetracarboxylic diandies dihalide used in the above [III] can be obtained by reacting the tetracarboxylic dianide obtained as described above with an appropriate chlorinating agent such as thionyl chloride.
The polyamic acid ester may have only an amic acid ester structure, or may be a partial esterified product in which an amic acid structure and an amic acid ester structure coexist. When the polyamic acid ester is obtained as a solution by the above reaction, the solution may be used as it is for the preparation of the liquid crystal alignment agent, or the polyamic acid ester contained in the reaction solution is isolated and then the liquid crystal alignment agent is used. It may be used for preparation.

<Polyimide>
The polyimide as the polymer (P) is a polymer having a partial structure represented by the above formula (2). The polyimide can be obtained, for example, by dehydrating and ring-closing the polyamic acid (P) synthesized as described above to imidize it. The polyimide may be a completely imidized product in which all of the amic acid structure possessed by the precursor polyamic acid (P) is dehydrated and ring-closed, and only a part of the amic acid structure is dehydrated and ring-closed to form an amic acid. It may be a partially imidized product in which the structure and the imide ring structure coexist. The polyimide has a preferably imidization ratio of 40 to 100%, more preferably 60 to 90%. This imidization ratio is expressed as a percentage of the ratio of the number of imide ring structures to the total number of amic acid structures and the number of imide ring structures of polyimide. Here, a part of the imide ring may be an isoimide ring.

The dehydration ring closure of the polyamic acid (P) is preferably carried out by dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydration ring closure catalyst to this solution, and heating as necessary. As the dehydrating agent, acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride can be used. The amount of the dehydrating agent used is preferably 0.01 to 20 mol per 1 mol of the amic acid structure of the polyamic acid. As the dehydration ring closure catalyst, for example, tertiary amines such as pyridine, collagen, lutidine, and triethylamine can be used. The amount of the dehydration ring closure catalyst used is preferably 0.01 to 10 mol with respect to 1 mol of the dehydrating agent used. Examples of the organic solvent used include organic solvents exemplified as those used for the synthesis of polyamic acid (P). The reaction temperature of the dehydration ring closure reaction is preferably 0 to 180 ° C., and the reaction time is preferably 1.0 to 120 hours. The reaction solution containing the polyimide thus obtained may be used as it is for the preparation of the liquid crystal alignment agent, or may be used for the preparation of the liquid crystal alignment agent after isolating the polyimide.

The solution viscosity of the polymer (P) is preferably 10 to 800 mPa · s, preferably 15 to 500 mPa · s, when a solution having a concentration of 10% by mass is used. Is more preferable. The solution viscosity (mPa · s) is E for a polymer solution having a concentration of 10% by mass prepared using a good solvent of the polymer (P) (for example, γ-butyrolactone, N-methyl-2-pyrrolidone, etc.). It is a value measured at 25 ° C. using a type rotary viscosity meter.
The polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) of the polymer (P) is preferably 1,000 to 500,000, more preferably 5,000 to 100,000. Is. The molecular weight distribution (Mw / Mn) represented by the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) measured by GPC is preferably 15 or less, more preferably 10 or less. The polymer (P) contained in the liquid crystal alignment agent may be only one kind or a combination of two or more kinds.

≪Other ingredients≫
The liquid crystal alignment agent of the present disclosure may further contain a component other than the polymer (P) (hereinafter, also referred to as “other component”). As other components, for example, a polymer having neither a partial structure represented by the above formula (1) nor a partial structure represented by the above formula (2) (hereinafter, also referred to as “another polymer”). ), Compounds with one or more epoxy groups in the molecule, functional silane compounds, compounds with one or more (meth) acryloyl groups in the molecule, antioxidants, metal chelate compounds, cure accelerators, surface activity Examples thereof include agents, fillers, dispersants, photosensitizers, acid generators, base generators, radical generators and the like. These blending ratios can be appropriately selected according to each compound as long as the effects of the present disclosure are not impaired.

<Other polymers>
The main skeleton of other polymers is not particularly limited, but for example, polyamic acid, polyimide, polyamic acid ester, polyorganosiloxane, polyester, cellulose derivative, polyacetal, polystyrene derivative, poly (styrene-phenylmaleimide) derivative, poly (meth). ) Examples thereof include polymers having acrylate or the like as a main skeleton. The other polymer is preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester and polyimide.

When the polymer component of the liquid crystal alignment agent of the present disclosure is composed of the polymer (P) and another polymer, at least one of the hydrogen-binding groups such as amino groups and amide groups of the polymer (P). Is preferably protected by a protective group. By introducing a protecting group into the hydrogen-bonding group, the polymer (P) becomes low in polarity, and when the liquid crystal alignment film is formed, the polymer (P) tends to be unevenly distributed on the air interface side. It is preferable in that the voltage retention rate can be improved.

When another polymer is blended in the liquid crystal alignment agent, the content ratio of the other polymer is based on the total amount of the polymer components in the liquid crystal alignment agent from the viewpoint of sufficiently obtaining the effect of blending the polymer (P). Therefore, 95% by mass or less is preferable, and 90% by mass or less is more preferable. As the other polymer, one type may be used alone, or two or more types may be used in combination.

<Solvent>
The liquid crystal alignment agent of the present disclosure is prepared as a liquid composition in which the polymer (P) and other components used as necessary are preferably dispersed or dissolved in a suitable solvent.
Examples of the organic solvent used include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,2-dimethyl-2-imidazolidinone, γ-butyrolactone, γ-butyrolactam, N, N-dimethylformamide. , N, N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone (diacetone alcohol), ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methylmethoxypropionate, ethylethoxypropionate, Ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol Diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisopentyl ether, ethylene carbonate, propylene carbonate, etc. Can be done. These can be used alone or in admixture of two or more.

The solid content 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) is appropriately selected in consideration of viscosity, volatility, etc., but is preferable. It is in the range of 1 to 10% by mass. That is, the liquid crystal alignment agent is applied to the surface of the substrate as described later and preferably heated to form a coating film which is a liquid crystal alignment film or a coating film which becomes a liquid crystal alignment film. At this time, when the solid content concentration is 1% by mass or more, the film thickness of the coating film can be sufficiently secured, which is preferable in that a good liquid crystal alignment film can be easily obtained. Further, when the solid content concentration is 10% by mass or less, the film thickness of the coating film does not become excessive and a good liquid crystal alignment film can be obtained, and the viscosity of the liquid crystal alignment agent can be appropriately secured to improve the coatability. Can be good.

The content ratio of the polymer (P) in the liquid crystal alignment agent is 100 parts by mass in total of the solid components (components other than the solvent) in the liquid crystal alignment agent from the viewpoint of sufficiently obtaining the effect of blending the polymer (P). On the other hand, it is preferably 2 parts by mass or more, and more preferably 5 parts by mass or more.

≪Liquid crystal alignment film and liquid crystal element≫
The liquid crystal alignment film of the present disclosure is formed by the liquid crystal alignment agent prepared as described above. Further, the liquid crystal element of the present disclosure includes a liquid crystal alignment film formed by using the liquid crystal alignment agent described above. The operation mode of the liquid crystal in the liquid crystal element is not particularly limited, and for example, TN (Twisted Nematic) type, STN (Super Twisted Nematic) type, VA (Vertical Alignment) type (including VA-MVA type, VA-PVA type, etc.), It can be applied to various modes such as IPS (In-Plane Switching) type, FFS (fringe field switching) type, OCB (Optically Compensated Bend) type and the like. 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 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 alignment agent is applied on the substrate, and preferably the coated surface is heated to form a coating film on the substrate. As the substrate, for example, glass such as float glass and soda glass; a transparent substrate made of plastic such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, and poly (aliphatic olefin) can be used. As the transparent conductive film provided on one surface of the substrate, a NESA film made of tin oxide (SnO ₂ ) (registered trademark of PPG, USA) and an ITO film made of indium oxide-tin oxide (In ₂ O ₃ -SnO ₂ ) are used. Etc. can be used. When manufacturing a TN type, STN type or VA type liquid crystal element, two substrates provided with a patterned transparent conductive film are used. On the other hand, in the case of manufacturing an IPS type or FFS type liquid crystal element, a substrate provided with an electrode made of a transparent conductive film or a metal film patterned in a comb tooth shape and a facing substrate not provided with an electrode are used. Is used. As the metal film, a film made of a metal such as chromium can be used. The liquid crystal alignment agent is applied to the substrate on the electrode forming surface, preferably by an offset printing method, a spin coating method, a roll coater method, or an inkjet printing method.

After the liquid crystal alignment agent is applied, preheating is preferably performed for the purpose of preventing the applied liquid crystal alignment agent from dripping. The prebake temperature is preferably 30 to 200 ° C., and the prebake time is preferably 0.25 to 10 minutes. Then, a firing (post-baking) step is carried out for the purpose of completely removing the solvent and, if necessary, thermally imidizing the amic acid structure present in the polymer. The firing temperature (post-baking temperature) at this time is preferably 80 to 300 ° C., and the post-baking time is preferably 5 to 200 minutes. The film thickness of the film thus formed is preferably 0.001 to 1 μm. By applying the liquid crystal alignment agent on the substrate and then removing the organic solvent, a liquid crystal alignment film or a coating film to be a liquid crystal alignment film is formed.

(Step 2: Orientation treatment)
When manufacturing a TN type, STN type, IPS type or FFS type liquid crystal element, a treatment (alignment treatment) for imparting a liquid crystal alignment ability to the coating film formed in the above step 1 is performed. As a result, the alignment ability of the liquid crystal molecules is imparted to the coating film to form a liquid crystal alignment film. As the alignment treatment, it is preferable to use a rubbing treatment in which the surface of the coating film formed on the substrate is rubbed with cotton or the like, or a photoalignment treatment in which the coating film is irradiated with light to impart a liquid crystal alignment ability. When manufacturing a vertically oriented liquid crystal element, the coating film formed in step 1 may be used as it is as a liquid crystal alignment film, and the coating film is subjected to an alignment treatment in order to further enhance the liquid crystal alignment ability. You may.

The light irradiation in the photoalignment process includes a method of irradiating the coating film after the post-baking step, a method of irradiating the coating film after the pre-baking step and before the post-baking step, and at least the pre-baking step and the post-baking step. In any of these methods, the method of irradiating the coating film while heating the coating film can be used. In the photo-alignment treatment, as the radiation to irradiate the coating film, for example, ultraviolet rays including light having a wavelength of 150 to 800 nm and visible light can be used. Preferably, it is ultraviolet light containing light having a wavelength of 200 to 400 nm. When the radiation is polarized, it may be linearly polarized or partially polarized. When the radiation to be used is linearly polarized light or partially polarized radiation, the irradiation may be performed from a direction perpendicular to the substrate surface, may be performed from an oblique direction, or may be performed in combination thereof. When irradiating unpolarized radiation, the direction of irradiation is diagonal.

As the light source to be used, for example, a low pressure mercury lamp, a high pressure mercury lamp, a deuterium hydrogen lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, an excima laser and the like can be used. The irradiation amount of radiation is preferably 400 to 20,000 J / m ² , and more preferably 1,000 to 5,000 J / m ² . The light irradiation on the coating film may be performed while heating the coating film in order to enhance the reactivity.

In the production of the liquid crystal alignment film, the coating film subjected to the light irradiation treatment may be heated within a temperature range of 120 ° C. or higher and 280 ° C. or lower. Such heat treatment is preferable in that the liquid crystal orientation is further improved (heat reorientation) and a liquid crystal element with a further reduced AC afterimage can be obtained. This heating may be post-baking, or may be a heat treatment performed after post-baking separately from post-baking. The heating temperature is preferably 140 ° C. or higher, more preferably 150 ° C. to 250 ° C., from the viewpoint of promoting the reorientation of the molecular chains by heating. The heating time is preferably 5 minutes to 200 minutes, more preferably 10 minutes to 60 minutes.

In the production of the liquid crystal alignment film, a contact step of contacting the coating film subjected to the light irradiation treatment with water, a water-soluble organic solvent, or a mixed solvent of water and a water-soluble organic solvent may be further included. Examples of the water-soluble organic solvent include methanol, ethanol, 1-propanol, isopropanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclopentanone. Examples of the contact method between the coating film and the solvent include, but are not limited to, a spray treatment, a shower treatment, a dipping treatment, and a liquid filling treatment. The contact time between the coating film and the solvent is not particularly limited, but is, for example, 5 seconds to 15 minutes. The coating film may be heat-treated after the contact step.

(Step 3: Construction of LCD cell)
A liquid crystal cell is manufactured by preparing two substrates on which a liquid crystal alignment film is formed as described above and arranging the liquid crystal between the two substrates arranged opposite to each other. In order to manufacture a liquid crystal cell, for example, (1) two substrates are arranged facing each other through a gap (spacer) so that the liquid crystal alignment films face each other, and the peripheral portion of the two substrates is used with a sealing agent. A method of sealing the injection holes after laminating, injecting and filling the liquid crystal in the surface of the substrate and the cell gap partitioned by the sealing agent, (2) Sealing at a predetermined place on one of the substrates on which the liquid crystal alignment film is formed. A method in which an agent is applied, liquid crystal is further dropped onto a predetermined number of places on the liquid crystal alignment film surface, the other substrate is bonded so that the liquid crystal alignment film faces each other, and the liquid crystal is spread over the entire surface of the substrate (ODF method). ) Etc. can be mentioned. It is desirable to remove the flow orientation at the time of filling the liquid crystal by further heating the manufactured liquid crystal cell to a temperature at which the used liquid crystal has an isotropic phase and then slowly cooling it to room temperature.

As the sealing agent, for example, an epoxy resin containing a curing agent and aluminum oxide spheres as a spacer can be used. As the spacer, a photo spacer, a bead spacer, or the like can be used.

As the liquid crystal display, either a positive type or a negative type may be used. When a negative type liquid crystal is used in the IPS type and FFS type liquid crystal elements, it is preferable in that the transmission loss at the upper part of the electrode can be reduced and the contrast can be improved. Examples of the liquid crystal include a nematic liquid crystal and a smectic liquid crystal, and among them, the nematic liquid crystal is preferable. Examples of the nematic liquid crystal include a shift-based liquid crystal, an azoxy-based liquid crystal, a biphenyl-based liquid crystal, a phenylcyclohexane-based liquid crystal, an ester-based liquid crystal, a terphenyl-based liquid crystal, a biphenylcyclohexane-based liquid crystal, a pyrimidine-based liquid crystal, a dioxane-based liquid crystal, and a bicyclooctane-based liquid crystal. A Cuban liquid crystal or the like can be used. Further, for example, a cholesteric liquid crystal, a chiral agent, a ferroelectric liquid crystal or the like may be added to these liquid crystals for use.

Subsequently, if necessary, a polarizing plate is attached to the outer surface of the liquid crystal cell. 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 iodine is absorbed is sandwiched between a cellulose acetate protective film, or a polarizing plate made of the H film itself. As a result, a liquid crystal element can be obtained.

The liquid crystal elements of the present disclosure can be effectively applied to various applications, for example, watches, portable game machines, word processors, notebook computers, car navigation systems, camcoders, PDAs, digital cameras, mobile phones, smartphones, and various types. It can be used for various display devices such as monitors, liquid crystal televisions and information displays, and dimming films. Further, the liquid crystal element formed by using the liquid crystal alignment agent of the present disclosure can also be applied to an optical film such as a retardation film.

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

The structures and abbreviations of the main compounds used in the following examples are as follows.
(Tetracarboxylic dianhydride)
TA-1; 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride TA-2; (1R, 2R, 3S, 4S) -1,3-dimethylcyclobutane-1,2,3,4-tetracarboxylic acid Acid dianhydride TA-3; 2,3,5-tricarboxycyclopentylacetic dianhydride TA-4; pyromellitic acid dianhydride TA-5; 4,4'-biphthalic acid dianhydride

(Diamine)
DA-1; N ¹ , N ⁴ -bis (2-((5-aminopyridine-2-yl) amino) ethyl) succinamide DA-2; N ¹ , N ⁴ -bis (2-((5-aminopyridine) amino) ethyl) -2-yl) (tert-butoxycarbonyl) amino) ethyl) succinamide DA-3; N, N'-bis (2-((5-aminopyridine-2-yl) amino) ethyl) urea DA-4; N , N'-bis (2-((5-aminopyridine-2-yl) (tert-butoxycarbonyl) amino) ethyl) urea DA-5; N ² , N ⁶ -bis (2-((5-aminopyridine) amino) ethyl) -2-yl) amino) ethyl) pyridine-2,6-diamine DA- ⁶ ; ^N2 , N6-bis (2-((5-aminopyridine-2-yl) (tert-butoxycarbonyl) amino) ethyl ) -N ² , N ⁶ -di (tert-butoxycarbonyl) pyridine-2,6-diamine DA-7; N, N'-bis (5-aminopyridine-2-yl) -N, N'-di ( tert-butoxycarbonyl) ethylenediamine DA-8; N1, N6-bis ( ^{4 -} aminophenethyl) ^-N1 , N6 ^- di (tert-butoxycarbonyl) adipamide DA-9; p-phenylenediamine DA-10; 3,5-Diaminobenzoic acid DA-11; 2,2'-dimethylbenzidine DA-12; 4,4'-diaminodiphenylmethane DA-13; N ⁴ , N ^4' -bis (4-aminophenyl) -N ⁴ , N ^4' -dimethylbenzidine DA-14; N ¹ , N ⁴ -bis (5-aminopyridine-2-yl) succinamide DA-15; N ¹ , N ⁴ -bis (5-aminopyridine-2-yl) -N ¹ , N ⁴ -dimethylsuccinamide

(End sealant)
EC-1; N- (tert-butoxycarbonyl) -ethylenediamine EC-2; maleic anhydride EC-3; 4-aminobenzoic acid

(Additive)
AD-1; N, N, N', N'-tetraglycidyl-4,4'-diaminodiphenylmethane AD-2; 3-glycidyloxypropyltriethoxysilane AD-3; dipentaerythritol hexaacrylate

(solvent)
NMP; N-methyl-2-pyrrolidone BC; butyl cellosolve THF; tetrahydrofuran EDC; 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride

<Compound synthesis>
[Synthesis Example 1]
Ethylenediamine (100 mL) and sodium carbonate (120 mmol) were placed in a three-necked flask equipped with a nitrogen introduction tube. A THF solution of 2-chloro-5-nitropyridine (120 mmol) was added dropwise under nitrogen, and the mixture was stirred at 50 ° C. for 6 hours. After completion of the reaction, the mixture was concentrated under reduced pressure, and NMP was added to the concentrated residue to dissolve it. The obtained solution was filtered to remove insoluble salts to obtain an NMP solution of N- (5-nitropyridin-2-yl) ethylenediamine.

In a three-necked flask equipped with a nitrogen introduction tube, succinic acid (10 mmol), EDC (22 mmol), and NMP (20 mL) were placed and stirred for 30 minutes, and N- (5-nitropyridin-2-yl) ethylenediamine (22 mmol) was added. ) Was added, and the mixture was stirred at room temperature for 4 hours. After completion of the reaction, the reaction solution was poured into water to precipitate the product. The precipitate was filtered and washed with water to give a dinitro compound (N1, N4-bis ( ² -((5-nitropyridin- ² -yl) amino) ethyl) succinamide) (yield 83%). ).
The above dinitro compound (5.0 mmol), di-tert-butyl dicarbonate (11 mmol), and NMP (10 mL) were placed in a three-necked flask equipped with a nitrogen introduction tube, and the mixture was stirred at room temperature for 8 hours. After completion of the reaction, ethyl acetate was added, and the mixture was washed separately with water. The organic phase was concentrated under reduced pressure to give a Boc-protected dinitro compound (N1, N4-bis ( ² -((5-nitropyridin- ² -yl) (tert-butoxycarbonyl) amino) ethyl) succinamide). (Yield 57%).
The Boc-protected dinitro compound (2.0 mmol), Pd / C (0.1 g), hydrazine monohydrate (20 mmol), and ethanol (10 mL) were placed in a three-necked flask equipped with a nitrogen introduction tube at room temperature. The mixture was stirred for 4 hours. After completion of the reaction, the reaction solution was filtered through Celite, ethyl acetate was added, and the mixture was washed separately with water. The organic phase was concentrated under reduced pressure to obtain a diamine represented by the above formula (DA-2) (yield 28%).

[Synthesis Example 2]
The diamine represented by the above formula (DA-1) was synthesized according to the following synthesis scheme.

[Synthesis Example 3]
A NMP solution of N- (5-nitropyridin-2-yl) ethylenediamine (30 mmol) and bis carbonate (4-nitrophenyl) (10 mmol) were placed in a three-necked flask equipped with a nitrogen introduction tube, and the mixture was placed at room temperature for 4 hours. Stirred. After completion of the reaction, the reaction solution was allowed to stand overnight to precipitate the product. The precipitate was filtered and washed with water to give a dinitro compound (N, N'-bis (2-((5-nitropyridin-2-yl) amino) ethyl) urea) (yield 78%). ..
The above dinitro compound (4.4 mmol), di-tert-butyl dicarbonate (9.7 mmol), DMAP (0.44 mmol), and NMP (10 mL) were placed in a three-necked flask equipped with a nitrogen introduction tube at room temperature. The mixture was stirred for 6 hours. After completion of the reaction, ethyl acetate was added, and the mixture was washed separately with water. The organic phase was concentrated under reduced pressure to give a Boc-protected dinitro compound (N, N'-bis (2-((5-nitropyridin-2-yl) (tert-butoxycarbonyl) amino) ethyl) urea) ( Yield 86%).
The Boc-protected dinitro compound (2.0 mmol), Pd / C (0.1 g), hydrazine monohydrate (20 mmol), and ethanol (10 mL) were placed in a three-necked flask equipped with a nitrogen introduction tube at room temperature. The mixture was stirred for 4 hours. After completion of the reaction, the reaction solution was filtered through Celite, ethyl acetate was added, and the mixture was washed separately with water. The organic phase was concentrated under reduced pressure to obtain a diamine represented by the above formula (DA-4) (yield 23%).

[Synthesis Example 4]
The diamine represented by the above formula (DA-3) was synthesized according to the following synthesis scheme.

[Synthesis Example 5]
The diamine represented by the above formula (DA-6) was synthesized according to the following synthesis scheme.

[Synthesis Example 6]
The diamine represented by the above formula (DA-5) was synthesized according to the following synthesis scheme.

[Synthesis Example 7]
The diamine represented by the above formula (DA-14) was synthesized according to the following synthesis scheme.

[Synthesis Example 8]
The diamine represented by the above formula (DA-15) was synthesized according to the following synthesis scheme.

<Synthesis of polymer>
[Synthesis Example 9]
Diamine (50 mol parts of (DA-1) and 50 mol parts of (DA-11)) and a terminal encapsulant (10 mol parts of (EC-1)) were dissolved in NMP and 0.95 with respect to the total amount of diamine. A molar equivalent of tetracarboxylic acid dianhydride (100 mol parts of (TA-2) to 100 mol parts of the total amount of tetracarboxylic acid dianhydride used in the synthesis) was added, and the reaction was carried out at room temperature for 6 hours to carry out a polyamic reaction. A solution of acid was obtained. To the obtained solution, 0.75 molar equivalents of 1-methylpiperidine and acetic anhydride were added as a dehydrating agent to the carboxyl group of the polyamic acid, and the mixture was heated and stirred at 60 ° C. for 3 hours. The obtained solution was repeatedly concentrated under reduced pressure and diluted with NMP to obtain a 10% by mass solution of polyimide (PI-1) having a partial structure represented by the following formula (PI-1). ¹ H-NMR spectrum (DMSO-d ⁶ , 400 MHz) of polyimide (PI-1) was measured, and aromatic protons (δ6.4 to 9.0 ppm) and main chain amide protons (δ9.8 to 10.3 ppm) were measured. When the imidization rate was calculated from the integral ratio of, the imidization rate was 76%.

[Synthesis Examples 10 to 16]
Polyimides (PI-2 to PI-8) were obtained in the same manner as in Synthesis Example 9, except that the types and molar ratios of the tetracarboxylic dianhydride and the diamine were changed as shown in Table 1 below. The numerical values in Table 1 indicate the ratio (mol%) of each compound to the total amount (100 mol%) of the tetracarboxylic dianhydride used in the synthesis for the tetracarboxylic dianhydride. The ratio (mol%) of each compound to the total amount (100 mol%) of the diamine used for the synthesis is shown. For the dehydrating agent, the ratio (mol%) of the polyamic acid to be used with respect to the amount of carboxyl groups (100 mol%) is shown.

[Synthesis Example 17]
Diamine (50 mol parts (DA-4) and 50 mol parts (DA-9)) was dissolved in NMP and 0.95 mol equivalents of tetracarboxylic acid dianhydride (tetra used for synthesis) with respect to the total amount of diamine. 75 mol parts (TA-2) and 25 mol parts (TA-1) were added to 100 mol parts of the total amount of carboxylic acid dianhydride, and the reaction was carried out at room temperature for 6 hours to obtain a polyamic acid solution. .. To the obtained solution, 0.50 molar equivalents of 1-methylpiperidine and acetic anhydride were added to the carboxyl group of the polyamic acid, and the mixture was heated and stirred at 60 ° C. for 3 hours. The obtained solution was repeatedly concentrated under reduced pressure and diluted with NMP to obtain a 10% by mass solution of polyimide (PI-9) having a partial structure represented by the following formula (PI-9). ¹ H-NMR spectrum (DMSO-d ^6,400 MHz) of polyimide (PI-9) was measured, and aromatic protons (δ6.4 to 9.0 ppm) and main chain amide protons (δ9.8 to 10.3 ppm) were measured. When the imidization rate was calculated from the integral ratio of the acetyl terminal amide proton (δ9.6 to 9.8 ppm), the imidization rate was 52%.

[Synthesis Example 18]
Polyimide (PI-10) was obtained in the same manner as in Synthesis Example 17, except that the types and molar ratios of tetracarboxylic dianhydride and diamine were changed as shown in Table 1 below.

[Synthesis Example 19]
Diamine (50 mol parts (DA-2) and 50 mol parts (DA-11)) was dissolved in NMP and 0.95 mol equivalents of tetracarboxylic acid dianhydride (tetra used for synthesis) with respect to the total amount of diamine. (TA-2) 100 mol parts) is added to 100 mol parts of the total amount of carboxylic acid dianhydride, and the reaction is carried out at room temperature for 6 hours. A 15% by weight solution of acid (PI-11) was obtained.

[Synthesis Example 20]
Tetracarboxylic dianhydride (TA-2) (40 mmol) and NMP (40 mL) were placed in a three-necked flask equipped with a nitrogen introduction tube and stirred at 100 ° C. for 30 minutes to diamine (DA-11) (20 mmol). ) Was added dropwise, and the mixture was stirred at 100 ° C. for 1 hour. Further, acetic anhydride (60 mmol) and N-methylpiperidine (10 mmol) were added, and the mixture was stirred at 100 ° C. for 1 hour. After completion of the reaction, the reaction solution was filtered and poured into water to precipitate the product. The precipitate was filtered, stirred and washed in boiling water and vacuum dried at 60 ° C. The obtained solid was anhydrous in excess acetic anhydride / acetic acid to obtain an intermediate (PI-12-1) represented by the following formula (PI-12-1).
Subsequently, the intermediate (PI-12-1) was dissolved in NMP, and 1.0 mol equivalent of diamine was added to the intermediate (100 mol parts of the total amount of diamine used in the synthesis (DA-2). 50 mol parts) was added, and the reaction was carried out at room temperature for 6 hours to obtain a 10% by mass solution of polyimide (PI-12) having a partial structure represented by the following formula (PI-12).

[Synthesis Example 21]
Diamine (75 mol parts (DA-2) and 25 mol parts (DA-11)) was dissolved in NMP and 0.95 mol equivalents of tetracarboxylic acid dianhydride (tetra used for synthesis) with respect to the total amount of diamine. 75 mol parts (TA-1) and 25 mol parts (TA-3) were added to 100 mol parts of the total amount of carboxylic acid dianhydride, and the reaction was carried out at room temperature for 6 hours. Further, an end-capping agent (10 mol parts of (EC-2)) was added and the reaction was carried out at room temperature for 3 hours, and 15 of the polyamic acid (PI-13) having a partial structure represented by the following formula (PI-13). A mass% solution was obtained.

[Synthesis Examples 22 to 25]
Polyamic acids (PI-14 to PI-17) were obtained in the same manner as in Synthesis Example 21 except that the types and molar ratios of the tetracarboxylic dianhydride and the diamine were changed as shown in Table 1 below.
[Synthesis Example 26]
Polyimide (PI-18) was obtained in the same manner as in Synthesis Example 17, except that the types and molar ratios of tetracarboxylic dianhydride and diamine were changed as shown in Table 1 below.

[Synthesis Example 27]
Diamine (50 mol parts (DA-2) and 50 mol parts (DA-8)) was dissolved in NMP and 0.95 mol equivalents of tetracarboxylic acid dianhydride (tetra used for synthesis) with respect to the total amount of diamine. (TA-4) 50 mol parts and (TA-3) 50 mol parts) were added to 100 mol parts of the total amount of carboxylic acid dianhydride, and the reaction was carried out at room temperature for 6 hours to carry out polyamic acid (PI-19). A 15% by mass solution of the above was obtained.

[Synthesis Examples 28 to 30]
Polyamic acids (PI-20 to PI-22) were obtained in the same manner as in Synthesis Example 27, except that the types and molar ratios of the tetracarboxylic dianhydride and the diamine were changed as shown in Table 1 below.

[Synthesis Example 31]
Diamine (75 mol parts of (DA-10) and 25 mol parts of (DA-12)) and terminal encapsulant (10 mol parts of (EC-3)) were dissolved in NMP and 0.95 with respect to the total amount of diamine. To a molar equivalent of tetracarboxylic acid dianhydride (75 mol parts of (TA-3) and 25 mol parts of (TA-1) to 100 mol parts of the total amount of tetracarboxylic acid dianhydride used in the synthesis) was added. The reaction was carried out at room temperature for 6 hours to obtain a 15% by mass solution of polyamic acid (PI-23).

[Synthesis Examples 32 to 34]
Polyamic acids (PI-24 to PI-26) were obtained in the same manner as in Synthesis Example 31 except that the types and molar ratios of the tetracarboxylic dianhydride and the diamine were changed as shown in Table 1 below.

[Synthesis Examples 35 and 36]
Polyimide (PI-27, PI-28) are the same as in Synthesis Example 17, except that the types and molar ratios of tetracarboxylic dianhydride and diamine, and the molar ratio of dehydrating agent are changed as shown in Table 1 below. ) Was obtained respectively.

<Preparation and evaluation of liquid crystal alignment agent>
[Example 1: Optical alignment FFS type liquid crystal display element]
(1) Preparation of liquid crystal aligning agent By diluting the polymer (solid content equivalent: (PI-1) 100 parts by mass) with NMP and butyl cellosolve (BC), the solid content concentration is 4.0% by mass and the solvent composition ratio. Obtained a solution having NMP: BC = 70: 30 (mass ratio). A liquid crystal alignment agent (R-1) was prepared by filtering this solution with a filter having a pore size of 0.2 μm.

(2) Evaluation of Solubility In the above (1), the solubility of the polymer was also evaluated. "Good" is when the polymer can be diluted and a sufficient amount of filtrate can be recovered when the solution is filtered through a filter. When the polymer is diluted, suspension or aggregation occurs, and the solution is filtered. The case where a sufficient amount of the filtrate could not be recovered when filtered was regarded as "defective". As a result, it was evaluated as "good" in this example.

(3) Formation of liquid crystal alignment film by photoalignment method On each surface of a glass substrate in which a flat plate electrode, an insulating layer and a comb-shaped electrode are laminated on one side in this order, and a facing glass substrate on which no electrode is provided. The liquid crystal alignment agent (R-1) prepared in (1) above was applied using a spinner, dried on a hot plate at 80 ° C. for 1 minute, and then the inside of the refrigerator was replaced with nitrogen in a 230 ° C. oven at 30 ° C. Drying was carried out for a minute to form a coating film having an average thickness of 0.1 μm. The surface of this coating film was subjected to photoalignment treatment by irradiating the surface of the coating film with ultraviolet rays of 300 mJ / cm ² containing a linearly polarized 254 nm emission line from the normal direction of the substrate using an Hg-Xe lamp. The coating film subjected to the photo-alignment treatment was heated in an oven at 230 ° C. in which the inside of the refrigerator was replaced with nitrogen for 30 minutes to perform heat treatment to form a liquid crystal alignment film.

(4) Manufacture of liquid crystal display element With respect to the pair of substrates having the liquid crystal alignment film produced in (3) above, aluminum oxide spheres having a diameter of 3.5 μm are contained, leaving a liquid crystal injection port on the edge of the surface on which the liquid crystal alignment film is formed. After applying the epoxy resin adhesive to the dispenser, the substrates were overlapped and pressure-bonded, and the adhesive was heat-cured at 150 ° C. for 1 hour. Next, a negative nematic liquid crystal (MJ2015NCMP manufactured by Merck) was filled between the pair of substrates from the liquid crystal injection port, and then the liquid crystal injection port was sealed with an epoxy adhesive. Further, in order to remove the flow orientation at the time of liquid crystal injection, the mixture was heated at 120 ° C. and then slowly cooled to room temperature.

(5) Evaluation of liquid crystal orientation (AC afterimage characteristics) For the liquid crystal display element manufactured in (4) above, a birefringence meter (AXOSTEP high-precision Muller matrix imaging polarimeter manufactured by AXOMETRICS) was used for 7 days at an AC voltage of 12 V. The change in the liquid crystal azimuth before and after driving was measured. A change in the liquid crystal azimuth of less than 1 degree was regarded as "good", and a change of 1 degree or more was regarded as "poor". It can be said that the smaller the change in the liquid crystal azimuth, the less likely the AC afterimage occurs even when the liquid crystal display element is driven for a long time, and the better the liquid crystal orientation. As a result, it was evaluated as "good" in this example.
(6) Evaluation of Voltage Retention Rate (Long-term Reliability) An ECB type liquid crystal display element was manufactured in the same manner as in (3) and (4) above except that the glass substrate was changed to ECB (Electrically Controlled Birefringence). The liquid crystal display element was allowed to stand on a backlight for 7 days and then heated in an oven at 70 ° C., and the voltage retention was measured by a voltage retention measuring device (VHR-1 manufactured by Toyo Corporation). A voltage of 1 V was applied for 60 microseconds in a cycle of 1 second, and a voltage holding ratio of 90% or more 1 second after the application was released was regarded as "good", and less than 90% was regarded as "bad". It can be said that the higher the measured value of the voltage holding ratio, the higher the reliability of the liquid crystal display element. As a result, it was evaluated as "good" in this example.

[Examples 2 to 13, Comparative Examples 1 to 3]
In Example 1, the liquid crystal alignment agent was prepared in the same manner as in Example 1 except that the polymer and the additive contained in the liquid crystal alignment agent were changed as shown in Table 2 below, and the liquid crystal alignment was performed by the photoalignment method. Along with forming a film, a liquid crystal display element was manufactured and various evaluations were performed. The evaluation results are shown in Table 2 below.

As shown in Table 2, the liquid crystal alignment agents of Examples 1 to 13 containing the polymer (P) have good solubility of the polymer, and a liquid crystal alignment film is formed by a photoalignment method to display an FFS type liquid crystal display. When the device was manufactured, both the liquid crystal orientation (AC afterimage characteristic) and the voltage retention rate (long-term reliability) were "good". On the other hand, the liquid crystal alignment agents of Comparative Examples 1 to 3 containing no polymer (P) were inferior to the examples in at least one of the solubility, the liquid crystal orientation, and the voltage retention rate of the polymer. ..

Here, considering the results of Examples 1 to 13 and Comparative Examples 1 to 3, all of Examples 1 to 13 are "good" and Comparative Example 1 is "poor" in terms of the solubility of the polymer. there were. A polymer having a hydrogen-bonding group that strongly interacts between molecules has a problem of low solubility in a solvent, but the polymer (P) has a specific spacer structure ( ^{-Y1 -} R3-". Since it has Y ^2- ) and a nitrogen-containing aromatic ring bonded to this spacer structure, it is presumed that the solubility of the polymer was good.

Specifically, in the case of an example having a thermally desorbable group (a bulky substituent can improve the solubility of the polymer, but if it is present on the surface of the film, it disturbs the liquid crystal orientation, so it is desirable to desorb by heat). The solubility of the polymer was good even when it had a hydrogen-binding group. For example, in Example 3, the polymer (P) has a urea bond and two Boc groups as protecting groups, and it is presumed that the solubility of the polymer is improved. As another factor for improving the solubility, it is considered that the protection of the amino group reduces the basicity of the polymer and suppresses the interaction with the remaining polyamic acid moiety.
On the other hand, in Comparative Example 1, although the polymer has a urea bond, it does not have a thermal desorption group, so that the solubility of the polymer (particularly, the solubility in BC which is a poor solvent) is high. It is presumed that it was defective.

Regarding the liquid crystal orientation, all of Examples 1 to 13 were "good", and Comparative Example 3 was "poor". This is because in Examples 1 to 13, the aromatic ring to which Y ¹ and Y ² are bonded is linked to the imide group, so that the photoinduced electron transfer from the diamine partial structure to the cyclobutane ring (electron transfer sensitization reaction) It is presumed that the photolysis by the retro [2 + 2] reaction of the cyclobutane ring was promoted. Further, in Examples 1 to 13, the polymer (P) has a divalent saturated aliphatic hydrocarbon group, the molecular chain has high flexibility, and the molecular chain due to molecular motion is generated in the heat treatment step after exposure. It is speculated that the self-organizing orientation of the is induced and the anisotropy is increased. As a result, it is presumed that in Examples 1 to 13, the anisotropy of the molecular orientation was efficiently exhibited with a small exposure amount, and the liquid crystal orientation was good. On the other hand, in Comparative Example 3, it is presumed that the liquid crystal orientation was poor because the photodecomposition reaction did not occur sufficiently.

Regarding the voltage holding ratio, all of Examples 1 to 13 were "good", and Comparative Examples 2 and 3 were "poor". In Examples 1 to 13, since the polymer (P) has a hydrogen-bonding group (amide bond, urea bond or 2,6-diaminopyridine skeleton), a multipoint hydrogen bond is formed between the molecules. As a result, the molecular motility of the liquid crystal display element in the operating temperature range is suppressed, the dielectric polarization of the liquid crystal alignment film is suppressed, and the movement and diffusion of impurities trapped in the liquid crystal alignment film are suppressed, and the voltage retention rate is suppressed. Is presumed to have improved. Furthermore, since the polymer (P) has a basic group (2-aminopyridine skeleton), it is derived from impurities (impurities derived from negative nematic liquid crystals, thermal / photodegradants, and liquid crystal sealants) present in the liquid crystal. It is presumed that the acidic components (formic acid, etc.) among the eluates to the liquid crystal display could be efficiently captured, and the voltage retention rate was improved. Furthermore, since the polymer (P) has a basic group, it interacts with the acidic group (carboxyl group, etc.) contained in the polymer (P), other polymers, additives, etc. between the molecules. It is presumed that physical cross-linking could be formed and the voltage retention rate was further improved.

If the voltage retention rate is good even after long-term driving, various display defects (for example, line afterimage; black-and-white checkered pattern display) caused by impurities in the liquid crystal display generated when the liquid crystal display element is used for a long period of time are displayed. It is possible to suppress the linear afterimage phenomenon that occurs at the pattern boundary observed when the entire surface is switched to grayscale display after the above, and there is a tendency to obtain a liquid crystal display element having excellent long-term reliability.

The polymers (P) of Examples 12 and 13 have the same monomer composition but different polymerization sequences. The polymer (P) of Example 12 is a random copolymer (PI-11) whose polymerization sequence is not controlled, whereas the polymer (P) of Example 13 is an alternating copolymer whose polymerization sequence is controlled. It is a polymer (PI-12) and has a structure in which repeating units derived from diamine (DA-2) and (DA-11) are alternately linked. Regarding the liquid crystal orientation, both Examples 12 and 13 were "good", but it was found that the change in the liquid crystal azimuth of Example 13 was smaller than that of Example 12 and the liquid crystal orientation was better. rice field.

This is because the alternate copolymer (PI-12) contains a relatively large amount of diamine and mesogen structures (aromatic rings, etc.) having a spacer structure (alkylene group, etc.) with high photoreactivity with respect to one cyclobutane ring site. It is presumed that both diamines having the above-mentioned structure are bonded to each other, and the photoreactivity and molecular motility of the polymer are uniform in the molecule. Therefore, it is presumed that the structural change caused by the photochemical reaction could more directly promote the change in the molecular orientation of the mesogen site. On the other hand, in the random copolymer (PI-11), a partial structure in which only one of a diamine having a highly photoreactive property and a spacer structure and a diamine having a mesogen structure are bonded to one cyclobutane ring site. It is presumed that the photoreactivity and molecular motility of the polymer are non-uniform within the molecule. Therefore, especially when the firing temperature is high, the molecular motility is locally increased, and it is presumed that the anisotropy of the molecular orientation due to the structural change caused by the photochemical reaction is easily alleviated. Although the polymer (P) of Comparative Example 2 is a random copolymer, it is known that the liquid crystal orientation is similarly improved when an alternating copolymer having a controlled polymerization sequence is used. ..

[Example 14]
Since the polymer (P) has a hydrogen-bonding group and a basic group, it tends to be highly polar. Therefore, when the polymer (P) is mixed with another low-polarity polymer having a low surface free energy to form a coating film, It is considered that it is more likely to be unevenly distributed on the substrate interface side than on the air interface side. Therefore, in order to verify the effect of the polymer blend of the polymer (P) and other polymers, a liquid crystal alignment agent was prepared in the same manner as in Example 1 except that the formulation was changed to the formulation shown in Table 3 below. A liquid crystal alignment film was formed by the optical alignment method, and various evaluations were performed by manufacturing a liquid crystal display element, and the results were compared with the results of Examples 1 to 13.

As a result, in Example 14, the liquid crystal orientation and the voltage retention rate were lower than those in Example 1 in which no other polymer was blended. It is presumed that this result is due to the fact that the polymer (PI-1) tends to be unevenly distributed on the interface side of the substrate.

On the other hand, when the polymer (P) has a thermal desorption group as a protecting group for a polar functional group such as an amino group, even when another polymer is blended, the liquid crystal orientation and liquid crystal orientation are higher than those in Example 14. The voltage holding ratio was good (Examples 2, 3, 5 to 13). This is relatively low when the polymer (P) has a thermal desorption group as a protective group for a polar functional group such as an amino group, and forms a coating film as a polymer blend with other polymers. However, it is presumed that the polymer (P) tends to be unevenly distributed on the air interface side, and as a result, good liquid crystal orientation and voltage retention can be exhibited.

[Example 15: rubbing orientation FFS type liquid crystal display element]
(1) Preparation of liquid crystal alignment agent Polymer (solid content conversion: (PI-11) 10 parts by mass, (PI-19) 45 parts by mass, (PI-21) 45 parts by mass) and additives ((AD-1) ) 5 parts by mass) was diluted with NMP and BC to obtain a solution having a solid content concentration of 4.0% by mass and a solvent composition ratio of NMP: BC = 70: 30 (mass ratio). A liquid crystal alignment agent (R-15) was prepared by filtering this solution with a filter having a pore size of 0.2 μm.

(2) Evaluation of Solubility In the above (1), the solubility of the polymer was also evaluated. The case where the polymer can be diluted and the solution can be filtered with a filter is regarded as "good", and the case where suspension or aggregation occurs when the polymer is diluted and the solution cannot be filtered with a filter is regarded as "poor". .. As a result, it was evaluated as "good" in this example.

(3) Formation of liquid crystal alignment film by rubbing method On each surface of a glass substrate in which a flat plate electrode, an insulating layer and a comb-shaped electrode are laminated on one side in this order, and a facing glass substrate on which no electrode is provided. The liquid crystal alignment agent (R-15) prepared in (1) above was applied using a spinner, dried on a hot plate at 80 ° C. for 1 minute, and then the inside of the refrigerator was replaced with nitrogen in an oven at 230 ° C. for 30 minutes. Drying was performed to form a coating film having an average thickness of 0.1 μm. Using a rubbing machine having a roll wrapped with a nylon cloth on the surface of this coating film, the rubbing treatment was performed twice at a roll rotation speed of 1000 rpm, a stage moving speed of 30 mm / sec, and a hair-foot pushing length of 0.3 mm. rice field. The coating film subjected to the rubbing alignment treatment was ultrasonically washed in ultrapure water for 1 minute and then dried in an oven at 100 ° C. for 10 minutes to form a liquid crystal alignment film.

(4) Manufacture of Liquid Crystal Display Element The FFS type liquid crystal display element was manufactured in the same manner as in Example 1 for the pair of substrates having the liquid crystal alignment film produced in (3) above.
(5) Evaluation of Liquid Crystal Orientation (AC Afterimage Characteristics) The liquid crystal display element manufactured in (4) above was evaluated for liquid crystal orientation (AC afterimage characteristics) in the same manner as in Example 1. As a result, it was evaluated as "good" in this example.
(6) Evaluation of Voltage Retention Rate (Long-Term Reliability) An ECB type liquid crystal display element was manufactured in the same manner as in (3) and (4) above except that the glass substrate was changed to ECB. The voltage retention rate (long-term reliability) of this liquid crystal display element was evaluated in the same manner as in Example 1. As a result, it was evaluated as "good" in this example.

[Examples 16 to 21, Comparative Examples 4 to 5]
In Example 15, the liquid crystal alignment agent was prepared in the same manner as in Example 15 except that the polymer and the additive contained in the liquid crystal alignment agent were changed as shown in Table 4 below, and the liquid crystal alignment film was prepared by a rubbing method. And manufactured a liquid crystal display element for various evaluations. The evaluation results are shown in Table 4 below.

As shown in Table 4, the liquid crystal alignment agents of Examples 15 to 21 containing the polymer (P) had good solubility of the polymer. Further, when the FFS type liquid crystal display element was manufactured by forming the liquid crystal alignment film by the rubbing method, both the liquid crystal orientation (AC afterimage characteristic) and the voltage retention rate (long-term reliability) were "good". On the other hand, the liquid crystal alignment agents of Comparative Examples 4 and 5 containing no polymer (P) had a lower voltage retention rate than that of the examples.

Here, considering the results of Examples 15 to 21 and Comparative Examples 4 and 5, all of Examples 15 to 21 were "good" with respect to the solubility of the polymer. This is because the polymers (P) of Examples 15 to 21 have a specific spacer structure, and as described above, the solubility of the polymers is good even though they have hydrogen-bonding groups. rice field.

Regarding the liquid crystal orientation, all of Examples 15 to 21 were "good". This is because the polymers (P) of Examples 15 to 21 have a divalent saturated aliphatic hydrocarbon group, have high flexibility of the molecular chain, and when shear stress is applied to the membrane by the rubbing method. It is presumed that this is because the orientation of the molecular chain is efficiently induced because the film is easily stretched.

Regarding the voltage holding ratio (long-term reliability), Examples 15 to 21 were all "good", and Comparative Examples 4 and 5 were "poor". The polymers (P) of Examples 15 to 21 have a hydrogen-bonding group and a basic group, and it is presumed that the voltage retention rate was good as described above. On the other hand, since the polymers used in Comparative Examples 4 and 5 do not have one or both of a hydrogen-bonding group and a basic group, it is presumed that the voltage retention rate was poor. It should be noted that this consideration is only speculation and does not limit the content of this disclosure in any way.

[Examples 22 and 23]
In Example 1 above, the polymer contained in the liquid crystal alignment agent was changed as shown in Table 5 below, and the irradiation amount of ultraviolet rays in the photoalignment treatment was changed to 500 mJ / cm ² in the same manner as in Example 1. , A liquid crystal alignment agent was prepared to form a liquid crystal alignment film by a photoalignment method, and a liquid crystal display element was manufactured and various evaluations were performed. The evaluation results are shown in Table 5 below.

As shown in Table 5, the liquid crystal alignment agents of Examples 22 and 23 containing the polymer (P) had good solubility of the polymer. Further, the obtained liquid crystal display element had both "good" liquid crystal orientation (AC afterimage characteristics) and voltage retention rate (long-term reliability).

From the above, it was found that the liquid crystal alignment agent of the present disclosure containing the polymer (P) can obtain a liquid crystal element having good liquid crystal orientation and voltage retention.

Claims (10)

A liquid crystal alignment agent containing a polymer (P) having at least one selected from the group consisting of a partial structure represented by the following formula (1) and a partial structure represented by the following formula (2).

(In the formulas (1) and (2), X ¹ is a tetravalent organic group. X ² is a divalent organic group represented by the following formula (3). R ¹ and R ² are. , Each independently is a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms.)

(In the formula (3), A ¹ and A ² are independently divalent aromatic groups, respectively. However, at least one of A ¹ and A ² is a divalent heterocycle having a nitrogen atom. It is a formula aromatic group.
Y ¹ and Y ² are independently single-bonded, "-O-", "-S-", "-NR ^4- ", "-COO-", "-NR ⁴ -CO-", or It is a divalent group having a nitrogen-containing non-aromatic heterocycle.
In R3 ^, at least one arbitrary methylene group in the divalent saturated aliphatic hydrocarbon group having 2 to 20 carbon atoms is "-O-", "-S-", and the following formulas (4) to (4) to formulas. (10)

It is a divalent organic group that is replaced with at least one of the groups represented by each of the above. However, R ³ contains at least one group in total among the groups represented by each of the above formulas (4) to (10). In R3 ^, the groups represented by "-O-", "-S-" and the above formulas (4) to (10) are not adjacent to each other, and "-O-", "-S-". And the two bonds of the groups represented by the above formulas (4) to (10) are attached to the carbon atoms constituting the hydrocarbon group, the nitrogen-containing non-aromatic heterocycle or the nitrogen-containing aromatic heterocycle, respectively. It is combined.
R ⁴ and R ⁵ are independently hydrogen atoms or monovalent organic groups, or R ⁴ and R ⁵ are combined with each other, and the nitrogen atom to which R ⁴ is bonded and R ⁵ are bonded. Represents a ring structure composed of nitrogen atoms. R ⁶ , R ⁷ and R ⁸ are independently hydrogen atoms or monovalent organic groups.
However, when R ³ contains any of the divalent groups represented by the above formulas (5) to (7), at least one of Y ¹ , Y ² and R ³ is a polar functional group. It has a protecting group.
A ³ is a divalent heterocyclic aromatic group having a nitrogen atom. "*" Indicates a bond. ) The liquid crystal alignment agent according to claim 1, wherein X ² has a protecting group for a polar functional group. The liquid crystal alignment agent according to claim 1 or 2, wherein X ² has two or more polar functional group protecting groups. The liquid crystal alignment agent according to any one of claims 1 to 3, wherein the polar functional group protecting group of X ² is a tert-butoxycarbonyl group. The X ² is any one of claims 1 to 4, which is a group represented by the following formula (11), a group represented by the following formula (12), or a group represented by the following formula (13). The liquid crystal alignment agent according to the section.

(In equations (11) to (13), Y ³ and Y ⁴ are independently "* ¹ -NR ⁹ -CO-" or "-NR ^{9 -} CO- * ¹ ", respectively. Indicates a bond with "-(CH ₂ ) _r- ". R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are independently hydrogen atoms or monovalent organic substances. However, in formula (12), at least one of Y ¹ , Y ² , R ¹⁰ and R ¹¹ has a protective group for a polar functional group. R is an integer of 1 to 6. S and t is an independently integer of 0 to 6. However, 1 ≦ r + s + t ≦ 12 is satisfied. V, w, e and f are independently integers of 1 to 6. u is 0 to 6. It is an integer of 2. A ¹ , A ² , Y ¹ and Y ² are synonymous with the above equation (3). “*” Indicates a bond.) The liquid crystal alignment agent according to any one of claims 1 to 5, wherein X ¹ is a tetravalent group represented by any of the following formulas (14) to (21).

(In equations (14) to (21), "*" indicates a bond.) A liquid crystal alignment film formed by using the liquid crystal alignment agent according to any one of claims 1 to 6. A liquid crystal element comprising the liquid crystal alignment film according to claim 7. A polymer having at least one selected from the group consisting of a partial structure represented by the following formula (1) and a partial structure represented by the following formula (2).

(In the formulas (1) and (2), X ¹ is a tetravalent organic group. X ² is a divalent organic group represented by the following formula (3). R ¹ and R ² are. , Each independently is a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms.)

(In the formula (3), A ¹ and A ² are independently divalent aromatic groups, respectively. However, at least one of A ¹ and A ² is a divalent heterocycle having a nitrogen atom. It is a formula aromatic group.
Y ¹ and Y ² are independently single-bonded, "-O-", "-S-", "-NR ^4- ", "-COO-", "-NR ⁴ -CO-", or It is a divalent group having a nitrogen-containing non-aromatic heterocycle.
In R3 ^, at least one arbitrary methylene group in the divalent saturated aliphatic hydrocarbon group having 2 to 20 carbon atoms is "-O-", "-S-", and the following formulas (4) to (4) to formulas. (10)

It is a divalent organic group that is replaced with at least one of the groups represented by each of the above. However, R ³ contains at least one group in total among the groups represented by each of the above formulas (4) to (10). In R3 ^, the groups represented by "-O-", "-S-" and the above formulas (4) to (10) are not adjacent to each other, and "-O-", "-S-". And the two bonds of the groups represented by the above formulas (4) to (10) are attached to the carbon atoms constituting the hydrocarbon group, the nitrogen-containing non-aromatic heterocycle or the nitrogen-containing aromatic heterocycle, respectively. It is combined.
R ⁴ and R ⁵ are independently hydrogen atoms or monovalent organic groups, or R ⁴ and R ⁵ are combined with each other, and the nitrogen atom to which R ⁴ is bonded and R ⁵ are bonded. Represents a ring structure composed of nitrogen atoms. R ⁶ , R ⁷ and R ⁸ are independently hydrogen atoms or monovalent organic groups.
However, when R ³ contains any of the divalent groups represented by the above formulas (5) to (7), at least one of Y ¹ , Y ² and R ³ is a polar functional group. It has a protecting group.
A ³ is a divalent heterocyclic aromatic group having a nitrogen atom. "*" Indicates a bond. ) A compound represented by the following formula (22).

(In the formula (22), A ¹ and A ² are independently divalent aromatic groups, respectively. However, at least one of A ¹ and A ² is a divalent heterocycle having a nitrogen atom. It is a formula aromatic group.
Y ¹ and Y ² are independently single-bonded, "-O-", "-S-", "-NR ^4- ", "-COO-", "-NR ⁴ -CO-", or It is a divalent group having a nitrogen-containing non-aromatic heterocycle.
In R3 ^, at least one arbitrary methylene group in the divalent saturated aliphatic hydrocarbon group having 2 to 20 carbon atoms is "-O-", "-S-", and the following formulas (4) to (4) to formulas. (10)

It is a divalent organic group that is replaced with at least one of the groups represented by each of the above. However, R ³ contains at least one group in total among the groups represented by each of the above formulas (4) to (10). In R3 ^, the groups represented by "-O-", "-S-" and the above formulas (4) to (10) are not adjacent to each other, and "-O-", "-S-". And the two bonds of the groups represented by the above formulas (4) to (10) are attached to the carbon atoms constituting the hydrocarbon group, the nitrogen-containing non-aromatic heterocycle or the nitrogen-containing aromatic heterocycle, respectively. It is combined.
R ⁴ and R ⁵ are independently hydrogen atoms or monovalent organic groups, or R ⁴ and R ⁵ are combined with each other, and the nitrogen atom to which R ⁴ is bonded and R ⁵ are bonded. Represents a ring structure composed of nitrogen atoms. R ⁶ , R ⁷ and R ⁸ are independently hydrogen atoms or monovalent organic groups.
However, when R ³ contains any of the divalent groups represented by the above formulas (5) to (7), at least one of Y ¹ , Y ² and R ³ is a polar functional group. It has a protecting group.
A ³ is a divalent heterocyclic aromatic group having a nitrogen atom. "*" Indicates a bond. )