JP7700975B2 - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element using the same - Google Patents

Description

The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element using the same.

Conventionally, liquid crystal devices have been widely used as display units for personal computers, mobile phones, smartphones, television receivers, etc. A liquid crystal device includes, for example, a liquid crystal layer sandwiched between an element substrate and a color filter substrate, pixel electrodes and a common electrode that apply an electric field to the liquid crystal layer, an alignment film that controls the alignment of the liquid crystal molecules in the liquid crystal layer, and thin film transistors (TFTs) that switch the electric signal supplied to the pixel electrodes. Known methods for driving liquid crystal molecules include vertical electric field methods such as the TN method and the VA method, and horizontal electric field methods such as the IPS method and the FFS (fringe field switching) method.

Currently, the most widely used liquid crystal alignment film in the industry is produced by rubbing the surface of a film made of polyamic acid and/or polyimide formed by imidizing polyamic acid on an electrode substrate in one direction with a cloth such as cotton, nylon, or polyester. Rubbing is a simple and highly productive industrially useful method. However, as liquid crystal display elements become more powerful, more precise, and larger, various problems have become evident, such as scratches on the surface of the alignment film caused by rubbing, dust generation, effects of mechanical force and static electricity, and even non-uniformity within the alignment treatment surface. As an alternative to rubbing, a photoalignment method is known in which liquid crystal alignment ability is imparted by irradiating polarized radiation. As liquid crystal alignment methods using photoalignment, methods using photoisomerization reaction, photocrosslinking reaction, photodecomposition reaction, etc. have been proposed (see Non-Patent Document 1 and Patent Document 1).

The liquid crystal alignment film, which is a component of a liquid crystal display element, is a film for uniformly aligning liquid crystals, but various other characteristics are required in addition to the uniform alignment of the liquid crystals. For example, there is a problem that electric charges accumulate in the liquid crystal alignment film due to the voltage that drives the liquid crystal, affecting the display as afterimages and burn-in (hereinafter referred to as residual DC-induced afterimages), significantly reducing the display quality of the liquid crystal display element. Therefore, liquid crystal alignment agents that overcome these issues have been proposed (see Patent Document 2).

In addition, in the IPS and FFS driving methods, the stability of the liquid crystal alignment is also important. If the liquid crystal alignment stability is low, the liquid crystal will not return to its initial state when driven for a long period of time, which can cause a decrease in contrast and image retention (hereinafter referred to as AC image retention). Patent Document 3 discloses a specific liquid crystal alignment agent as a method for solving the above problem.

Furthermore, with the spread of tablets and smartphones, development of narrow-framed liquid crystal display elements that ensure as wide a display area as possible is underway. This narrowing of the frame has made it necessary to apply a sealant onto the liquid crystal alignment film, and Patent Document 4 discloses a liquid crystal alignment agent that maintains liquid crystal alignment and has good adhesion to the sealant.

Japanese Patent Publication No. 9-297313 International Publication No. 2005/083504 International Publication No. 2015/050135 International Publication No. 2015/060360

"Liquid Crystal Photo-Alignment Film" Kidowaki, Ichimura, Functional Materials, November 1997, Vol. 17, No. 11, pp. 13-22

Furthermore, there is an ever-increasing demand for higher definition liquid crystal display elements, and it is becoming more important than ever to exhibit good display quality.
The present invention has been made in consideration of the above circumstances, and has as its main object to provide a liquid crystal alignment film that has good liquid crystal alignment properties and good adhesion to a sealant, and a liquid crystal alignment agent that enables a narrow frame due to the good adhesion between the liquid crystal alignment film and the sealant, thereby enabling the production of a liquid crystal display element that exhibits good display quality.

（Ｒ_１からＲ_４はそれぞれ独立して、水素原子、ハロゲン原子、炭素数１～６のアルキル基、炭素数２～６のアルケニル基、炭素数２～６のアルキニル基、フッ素原子を含有する炭素数１～６の１価の有機基、又はフェニル基であり、同一でも異なってよいが、Ｒ_１からＲ_４の少なくとも一つは上記定義中の水素原子以外の基を表す。Ｙ_１は下記式（Ｈ）で表される部分構造を有する２価の有機基を表す。）

（Ｑ^３は－（ＣＨ_２）_ｎ－で表される構造であり（ｎは２～２０の整数である。）、任意の－ＣＨ_２－は－Ｏ－及び－Ｃ（＝Ｏ）－から選ばれる基に置き換えられてもよいが、酸素原子同士が直接結合することはない。２つのベンゼン環上の任意の水素原子は１価の有機基で置き換えられてもよい。＊は結合手を表す。）

（Ｘ_２は、５員環以上の脂環構造を有する４価の有機基である。Ｙ_２は上記式（Ｈ）で表される部分構造を有する２価の有機基を表す。）

（式（３）におけるＲ_３１からＲ_３４は、それぞれ、上記式（１）のＲ_１からＲ_４と同義である。式（４）におけるＸ_４は上記式（２）のＸ_２と同義である。Ｙ_３、Ｙ_４は下記式（Ｉ）で表される２価の有機基を表す。）

（＊は結合手を表す。） As a result of intensive research, the present inventors have found that the above problems can be solved by using a liquid crystal aligning agent containing a polymer component having a specific repeating unit, and have thus completed the present invention.
The present invention relates to the following.
A liquid crystal aligning agent comprising a polymer (A) having repeating units represented by the following formulae (1), (2), (3) and (4).

(R ₁ to R ₄ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group, and may be the same or different, but at least one of R ₁ to R ₄ represents a group other than a hydrogen atom as defined above. _{Y 1} represents a divalent organic group having a partial structure represented by the following formula (H).)

( ^Q3 is a structure represented by -(CH ₂ ) _n - (n is an integer from 2 to 20), and any -CH ₂ - may be replaced by a group selected from -O- and -C(=O)-, but the oxygen atoms are not directly bonded to each other. Any hydrogen atoms on the two benzene rings may be replaced by a monovalent organic group. * represents a bond.)

( _X2 represents a tetravalent organic group having an alicyclic structure having 5 or more members. _Y2 represents a divalent organic group having a partial structure represented by the above formula (H).)

( _R31 to _R34 in formula (3) are respectively defined as _R1 to _R4 in formula (1). _X4 in formula (4) is respectively defined as _X2 in formula (2). _Y3 and _Y4 represent a divalent organic group represented by the following formula (I).)

(* represents a bond.)

The liquid crystal alignment agent of the present invention provides a liquid crystal alignment film that has good alignment of the liquid crystal and good adhesion to the sealant, and the good adhesion between the liquid crystal alignment film and the sealant makes it possible to further narrow the frame, resulting in a liquid crystal display element that exhibits good display quality.

Each component contained in the liquid crystal aligning agent of the present invention and other components that are optionally blended as necessary will be described below.
<Polymer (A)>
The liquid crystal aligning agent of the present invention contains a polymer (A) having repeating units represented by the above formula (1), (2), (3) and (4). By adopting such a constitution, a liquid crystal alignment film with little AC afterimage can be obtained, and a liquid crystal display element with excellent contrast can be obtained.

In the above formulas (1) and (2), _X2 , _Y1 , _Y2 , _R1 , _R2 , _R3 and _R4 are as defined above.

Specific examples of the alkyl group having 1 to 6 carbon atoms in R ₁ to R ₄ include a methyl group, an ethyl group, a propyl group, an i-propyl group, an n-butyl group, an i-butyl group, an s-butyl group, a t-butyl group, and an n-pentyl group. Specific examples of the alkenyl group having 2 to 6 carbon atoms in R ₁ to R ₄ include a vinyl group, a propenyl group, and a butynyl group, which may be linear or branched. Specific examples of the alkynyl group having 2 to 6 carbon atoms in R ₁ to R ₄ include an ethynyl group, a 1-propynyl group, and a 2-propynyl group. Examples of the halogen atom in R ₁ to R ₄ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom include a fluoromethyl group and a trifluoromethyl group. From the viewpoint of high photoreactivity, R ₁ to R ₄ are hydrogen atoms or methyl groups, and it is preferable that at least one of R ₁ to R ₄ is a methyl group, and more preferable that at least two of R ₁ to R ₄ are methyl groups. It is even more preferable that R ₁ and R ₄ are methyl groups, and R ₂ and R ₃ are hydrogen atoms.

Specific examples of the monovalent organic group substituting any hydrogen atom on the benzene ring in the above formula (H) include a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, and a monovalent organic group having 1 to 6 carbon atoms and containing a fluorine atom, such as the structures exemplified above for R ₁ to R ₄ .
As the partial structure represented by the above formula (H), from the viewpoint of reducing the occurrence of AC afterimages, partial structures represented by any of the following formulas (H-1) to (H-7) can be mentioned.

Preferred specific examples of _Y1 in the above formula (1) include divalent organic groups represented by any of the following formulae (h-1) to (h-8), from the viewpoint of reducing the occurrence of AC afterimages.

The polymer (A) has a repeating unit represented by the above formula (2) from the viewpoint of increasing heat resistance.
The tetravalent organic group of _X2 in formula (2) is preferably a tetravalent organic group having a 5- to 8-membered alicyclic structure, and more preferably a tetravalent organic group having a 5- to 7-membered alicyclic structure. In addition, when the alicyclic structure to which the imide group is bonded is a polycyclic structure, the alicyclic structure having 5 or more members means that the number of atoms constituting the ring in each ring contained in the polycyclic structure is 5 or more. In addition, the alicyclic structure may be bonded to at least one of the two imide groups, and may have a chain hydrocarbon structure or an aromatic ring structure together with the alicyclic structure.

Preferred specific examples of _X2 include tetravalent organic groups represented by any of the following formulas (X2-1) to (X2-12).

From the viewpoints of reducing the occurrence of AC afterimages and increasing the contrast of the liquid crystal display element, _X2 in formula (2) is more preferably any one of (X2-1) to (X2-4).
Preferred specific examples of _Y2 in the above formula (2) are the same as the preferred specific examples of _Y1 in the above formula (1).

From the viewpoint of reducing AC image retention, the polymer (A) preferably contains 1 to 95 mol %, more preferably 5 to 90 mol %, of the total of the repeating units represented by the above formula (1) and the repeating units represented by the above formula (2), based on all repeating units.
The ratio ((1):(2)) of the repeating unit represented by the above formula (1) to the repeating unit represented by the above formula (2) in the polymer (A) is preferably from 70:30 to 99:1, more preferably from 75:25 to 98:2, and even more preferably from 80:20 to 97:3.

The polymer (A) has a repeating unit represented by the above formula (3) and a repeating unit represented by the above formula (4) from the viewpoint of improving the contrast and seal adhesion of a liquid crystal display device.
From the viewpoint of reducing AC afterimages, the polymer (A) preferably contains 5 to 99 mol %, and more preferably 10 to 95 mol %, of the sum of the repeating units represented by the above formula (3) and the repeating units represented by the above formula (4) based on the total repeating units.
The ratio ((3):(4)) of the repeating unit represented by the above formula (3) to the repeating unit represented by the above formula (4) in the polymer (A) is preferably 70:30 to 99:1, more preferably 75:25 to 98:2, and even more preferably 80:20 to 97:3.

The ratio ((1):(3)) of the repeating unit represented by the above formula (1) to the repeating unit represented by the above formula (3) in the polymer (A) is preferably 1:99 to 99:1, more preferably 5:95 to 80:20, and even more preferably 10:90 to 70:30.
The ratio ((2):(4)) of the repeating unit represented by the above formula (2) to the repeating unit represented by the above formula (4) in the polymer (A) is preferably 1:99 to 99:1, more preferably 5:95 to 80:20, and even more preferably 10:90 to 70:30.

The polymer (A) preferably contains 6 to 100 mol %, and more preferably 15 to 100 mol %, of the repeating units represented by the above formulas (1), (2), (3) and (4) relative to the total repeating units contained in the polymer (A).

（Ｒ_５１からＲ_５４は、それぞれ、上記式（１）のＲ_１からＲ_４と好ましい具体例も含めて同義であり、Ｙ_５、Ｙ_６は、それぞれ独立して、下記式（Ｊ－１）で表される部分構造を有する２価の有機基、又は下記式（Ｊ－２）で表される２価の有機基を表す。式（６）におけるＸ_６は上記式（２）のＸ_２と同義である。）

From the viewpoint of further enhancing adhesion to a sealing material, the polymer (A) may have at least one type of repeating unit selected from the group consisting of a repeating unit represented by the following formula (5) and a repeating unit represented by the following formula (6):

( _R51 to _R54 are respectively defined as _R1 to _R4 in the above formula (1), including preferred specific examples, and _Y5 and _Y6 each independently represent a divalent organic group having a partial structure represented by the following formula (J-1) or a divalent organic group represented by the following formula (J-2). _X6 in formula (6) is defined as _X2 in the above formula (2).)

In the above formulae (J-1) and (J-2), _Q5 is a _single bond, -( _CH2 ) _n- (n is an integer of 1 to 20), or a group which can be replaced by -O-, _-COO- , -OCO-, -NQ9-, _-NQ9CO- , _-CONQ9- , _-NQ9CONQ10- , _-NQ9COO- , or -OCOO-, provided that any -CH2- in -( _{CH2 )} n- are not adjacent to each other. _{Q9 and Q10} each independently represent a hydrogen atom or a monovalent organic group.
Q ₆ and Q ₇ each independently represent -H, -NHD, -N(D) ₂ , a group having -NHD, or a group having -N(D) _2. Q ₈ represents -NHD, -N(D) ₂ , a group having -NHD, or a group having -N(D) _2. D represents a carbamate protecting group, and examples of the carbamate protecting group include a tert-butoxycarbonyl group and a 9-fluorenylmethoxycarbonyl group. However, at least one of Q ₅ , Q ₆ , and Q ₇ has a carbamate protecting group in the group. *1 represents a bond.

Preferred specific examples of Y ₅ and Y ₆ from the viewpoint of reducing AC image retention include divalent organic groups represented by any one of the following formulas (J-1-a) to (J-1-d) and (J-2-1): Boc represents a tert-butoxycarbonyl group.

The polymer (A) may further have at least one repeating unit selected from the group consisting of repeating units represented by the following formulae (PI-A-1) and (PA-1), in addition to the repeating units represented by the above formulae (1) to (4) and the repeating units represented by the above formulae (5) and (6).

（Ｒ_１、Ｒ_２、Ｒ_３、Ｒ_４は、上記式（１）のＲ_１、Ｒ_２、Ｒ_３、Ｒ_４と同義である。） In formula (PI-A-1), X _I1 represents a tetravalent organic group, and Y _I1 represents a divalent organic group. However, when X _I1 is the same as the tetravalent organic group represented by the following formula (g) or X ₂ in the above formula (2), Y _I1 represents a structure other than a divalent organic group having a partial structure represented by the above formula (H), a divalent organic group represented by the above formula (I), a divalent organic group having a partial structure represented by the above formula (J-1), and a divalent organic group represented by the above formula (J-2). Examples of X _I1 include a tetravalent organic group represented by the following formula (g), a tetravalent organic group exemplified as X ₂ in the above formula (2), a tetravalent organic group represented by any of the following formulas (X _I1 -1) to (X _I1 -13), and a tetravalent organic group derived from an aromatic tetracarboxylic dianhydride.

(R ₁ , R ₂ , R ₃ , and R ₄ are the same as R ₁ , R ₂ , R ₃ , and R ₄ in the above formula (1).)

（ｘ及びｙは、それぞれ独立に、単結合、エーテル（－Ｏ－）、カルボニル（－ＣＯ－）、エステル（－ＣＯＯ－）、炭素数１～５のアルカンジイル基、１，４－フェニレン、スルホニル、又はアミド基である。ｊ及びｋは、０又は１である。＊は結合手を表す。）

The aromatic tetracarboxylic acid dianhydride that gives the tetravalent organic group of _X11 is an acid dianhydride obtained by intramolecular dehydration of a carboxyl group bonded to an aromatic ring such as a benzene ring or a naphthalene ring. Specific examples include a tetravalent organic group represented by any one of the following formulae (X3-1) to (X3-2) and a tetravalent organic group represented by any one of the following formulae (Xr-1) to (Xr-7).

(x and y each independently represent a single bond, an ether (-O-), a carbonyl (-CO-), an ester (-COO-), an alkanediyl group having 1 to 5 carbon atoms, 1,4-phenylene, a sulfonyl, or an amide group. j and k each represent 0 or 1. * represents a bond.)

In formula (PI-A-1), specific examples of the divalent organic group of Y _I1 include a divalent organic group having a partial structure represented by the above formula (H), a divalent organic group represented by the above formula (I), a divalent organic group having a partial structure represented by the above formula (J-1), and a divalent organic group represented by the above formula (J-2), as well as a divalent organic group represented by any one of the following formulas (o-1) to (o-23), and a group represented by any one of formulas (Y-1) to (Y-167) described in International Publication No. WO 2018/117239.

In formula (PA-1), X represents a tetravalent _organic group, and _Y represents a divalent organic group. Specific examples of _X include the structures exemplified for _X in formula (PI-A-1). Specific examples of _Y include the structures exemplified for _Y in formula (PI-A-1).

In formula (PA-1), R _A1 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. _{Z A11} and Z _A12 are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkenyl group having 2 to 10 carbon atoms which may have a substituent, an alkynyl group having 2 to 10 carbon atoms which may have a substituent, a tert-butoxycarbonyl group, or a 9-fluorenylmethoxycarbonyl group.

Specific examples of the alkyl group having 1 to 5 carbon atoms for R _A1 include a methyl group, an ethyl group, a propyl group, an i-propyl group, an n-butyl group, an i-butyl group, an s-butyl group, a t-butyl group, an n-pentyl group, etc. From the viewpoint of ease of imidization by heating, R ₁ is preferably a hydrogen atom or a methyl group.

Specific examples of the alkyl group having 1 to 10 carbon atoms for Z _A11 and Z _A12 include, in addition to the specific examples of the alkyl group having 1 to 5 carbon atoms exemplified for R ₁ above, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, etc. Specific examples of the alkenyl group having 2 to 10 carbon atoms for Z _A11 and Z _A12 above include a vinyl group, a propenyl group, a butynyl group, etc., which may be linear or branched. Specific examples of the alkynyl group having 2 to 10 carbon atoms for Z _A11 and Z _A12 above include an ethynyl group, a 1-propynyl group, a 2-propynyl group, etc.
Z _A11 and Z _A12 may each have a substituent, and examples of the substituent include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), a hydroxyl group, a cyano group, and an alkoxy group.

When the polymer A contains the repeating units represented by the formula (5) and the repeating units represented by the formula (6), the ratio ((5):(6)) is preferably 70:30 to 99:1, more preferably 75:25 to 98:2, and even more preferably 80:20 to 97:3.

In the polymer (A), the sum of the repeating units represented by the formula (5) and the repeating units represented by the formula (6) is preferably 1 to 40 mol %, more preferably 1 to 30 mol %, and even more preferably 5 to 30 mol %, based on the total repeating units contained in the polymer (A).
In this case, the total of the repeating units represented by the above formulas (1), (2), (3) and (4) is preferably 6 to 99 mol %, more preferably 15 to 99 mol %, and still more preferably 15 to 95 mol %, based on the total repeating units contained in the polymer (A).

<Second Polymer>
The liquid crystal aligning agent of the present invention is a composition containing the above polymer (A) and an organic solvent, and may contain two or more polymers (A) having different structures. The liquid crystal aligning agent of the present invention may also contain a polymer other than the polymer (A) (hereinafter, also referred to as a second polymer) and various additives.
When the liquid crystal aligning agent of the present invention contains a second polymer, the content ratio of the polymer (A) to the total polymer components is preferably 5 mass% or more, more preferably 5 to 95 mass%, and more preferably 10 to 90 mass%.

Examples of the second polymer include polyamic acid, polyimide, polyamic acid ester, polyester, polyamide, polyurea, polyorganosiloxane, cellulose derivative, polyacetal, polystyrene or its derivative, poly(styrene-phenylmaleimide) derivative, poly(meth)acrylate, etc.

In particular, a polyamic acid obtained from a tetracarboxylic dianhydride component and a diamine component (hereinafter also referred to as a second polyamic acid) is preferred as the second polymer.

（Ａは４価の有機基であり、好ましくは炭素数４～３０の４価の有機基である。） An example of the tetracarboxylic dianhydride component for obtaining the second polyamic acid is a compound represented by the following formula (11): The tetracarboxylic dianhydride component may be composed of two or more types of compounds.

(A is a tetravalent organic group, preferably a tetravalent organic group having 4 to 30 carbon atoms.)

Preferred examples of A are shown below, but the present invention is not limited to these.

Of the above, (A-1) and (A-2) are preferred from the viewpoint of further improving the photoalignment properties, (A-4) is preferred from the viewpoint of further improving the relaxation speed of the accumulated charge, and (A-15) to (A-17) are preferred from the viewpoint of further improving the liquid crystal alignment properties and the relaxation speed of the accumulated charge.

（Ｙ_９は２価の有機基を表す。２つのＡ_９は、それぞれ独立して、水素原子又は、炭素数１～５のアルキル基、炭素数２～５のアルケニル基、又は炭素数２～５のアルキニル基である。液晶配向性の観点から、Ａ_９は水素原子又はメチル基が好ましい。） The diamine component for obtaining the second polyamic acid can be appropriately determined depending on the purpose, and for example, a diamine represented by the following formula (12) can be used.

(Y ₉ represents a divalent organic group. Two A ₉ are each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms. From the viewpoint of liquid crystal alignment, A ₉ is preferably a hydrogen atom or a methyl group.)

For the purpose of improving the electrical properties and relaxation properties, Y ₉ is preferably a divalent organic group having a secondary or tertiary nitrogen atom, or a divalent organic group having --NH--CO--NH-- in the molecule.
Specific examples of the diamine represented by formula (12) when Y ₉ is a divalent organic group having a secondary or tertiary nitrogen atom include any of the following diamines (a) to (d).

（Ｒ^１は水素原子、フッ素原子、シアノ基、ヒドロキシ基、又はメチル基を表す。２つのＲ^２は、それぞれ独立して、単結合又は基「＊１－Ｒ^３－Ｐｈ－＊２」を表し、Ｒ^３は、単結合、－Ｏ－、－ＣＯＯ－、－ＯＣＯ－、－（ＣＨ_２）_ｌ－、－Ｏ（ＣＨ_２）_ｍＯ－、－ＣＯＮＨ－、及び－ＮＨＣＯ－から選ばれる２価の有機基を表す。ｌ、ｍは１～５の整数を表す。＊１は式（ｐｒ）中のベンゼン環と結合する部位を表し、＊２は式（ｐｒ）中のアミノ基と結合する部位を表す。Ｐｈはフェニレン基を表す。ｎは１～３である。） (a) A diamine having a pyrrole structure as described in WO2017/126627, preferably a diamine having a structure represented by the following formula (pr):

(R ¹ represents a hydrogen atom, a fluorine atom, a cyano group, a hydroxy group, or a methyl group. Two R ^2s each independently represent a single bond or a group "*1-R ³ -Ph-*2", and R ³ represents a divalent organic group selected from a single bond, -O-, -COO-, -OCO-, -(CH ₂ ) _l -, -O(CH ₂ ) _m O-, -CONH-, and -NHCO-. l and m represent integers of 1 to 5. *1 represents a site bonded to the benzene ring in formula (pr), and *2 represents a site bonded to the amino group in formula (pr). Ph represents a phenylene group, and n is 1 to 3.)

(b) A diamine having a pyrrole structure as described in WO2018/062197, preferably a diamine having a structure represented by the following formula (pn):

（Ｒ^１及びＲ^２は、それぞれ独立に、水素原子又はメチル基を表す。Ｒ^３は単結合又は基「＊１－Ｒ^４－Ｐｈ－＊２」を表し、Ｒ^４は単結合、－Ｏ－、－ＣＯＯ－、－ＯＣＯ－、－（ＣＨ_２）_ｌ－、－Ｏ（ＣＨ_２）_ｍＯ－、－ＣＯＮＨ－、及び－ＮＨＣＯ－から選ばれる２価の有機基を表し（ｌ、ｍは１～５の整数を表す）、＊１は式（ｐｎ）中のベンゼン環と結合する部位を表し、＊２は式（ｐｎ）中のアミノ基と結合する部位を表す。Ｐｈはフェニレン基を表す。ｎは１～３を表す。）

( ^R1 and ^R2 each independently represent a hydrogen atom or a methyl group. ^R3 represents a single bond or a group "*1- ^R4 -Ph-*2", ^R4 represents a single bond, a divalent organic group selected from -O-, -COO-, -OCO-, -( _CH2 ) _l- , -O( _CH2 ) _mO- , -CONH-, and -NHCO- (l and m represent integers of 1 to 5), *1 represents a site bonded to the benzene ring in formula (pn), *2 represents a site bonded to the amino group in formula (pn), Ph represents a phenylene group, and n represents 1 to 3.)

（Ｒ^１は水素原子又はメチル基を表し、Ｒ^２はメチル基を表す。） (c) A diamine having a carbazole structure described in WO2018/110354, preferably a diamine having a structure represented by the following formula (cz):

( ^R1 represents a hydrogen atom or a methyl group, and ^R2 represents a methyl group.)

（Ｘはビフェニル環又はフルオレン環である。Ｙはベンゼン環、ビフェニル環、又は－Ｐｈ－Ｚ－Ｐｈ－から選ばれる基であり、Ｐｈはフェニレン基を表す。Ｚは－Ｏ－、－ＮＨ－、－ＣＨ_２－、－ＳＯ_２－、－Ｃ（ＣＨ_３）_２－又は－Ｃ（ＣＦ_３）_２－で表される２価の基である。Ａ及びＢは、水素原子又はメチル基である。）、２，３－ジアミノピリジン、２，６－ジアミノピリジン、３，４－ジアミノピリジン、２，４－ジアミノピリミジン、５，６－ジアミノ－２，３－ジシアノピラジン、５，６－ジアミノ－２，４－ジヒドロキシピリミジン、２，４－ジアミノ－６－ジメチルアミノ－１，３，５－トリアジン、１，４－ビス（３－アミノプロピル）ピペラジン、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、２，４－ジアミノ－６－イソプロポキシ－１，３，５－トリアジン、２，４－ジアミノ－６－メトキシ－１，３，５－トリアジン、２，４－ジアミノ－６－フェニル－１，３，５－トリアジン、２，４－ジアミノ－６－メチル－１，３，５－トリアジン、２，４－ジアミノ－１，３，５－トリアジン、４，６－ジアミノ－２－ビニル－１，３，５－トリアジン、３，５－ジアミノ－１，２，４－トリアゾール、６，９－ジアミノ－２－エトキシアクリジンラクテート、３，８－ジアミノ－６－フェニルフェナントリジン、１，４－ジアミノピペラジン、３，６－ジアミノアクリジン、ビス（４－アミノフェニル）－Ｎ－フェニルアミン、４，４’－ジフェニル－Ｎ－メチルアミン、４，４’－ジアミノジフェニルアミン、３，６－ジアミノカルバゾール、９－メチル－３，６－ジアミノカルバゾール、９－エチル－３，６－ジアミノカルバゾール、下記式（ｗ１）又は（ｗ２）で表されるジアミン。 (d) diamines having a nitrogen-containing heterocycle as described in paragraphs [0173] to [0188] of WO2015/046374 and diamines having a nitrogen-containing structure as described in paragraph [0050] of JP2016-218149A; diamines represented by the following formula (BP):

(X is a biphenyl ring or a fluorene ring; Y is a benzene ring, a biphenyl ring, or a group selected from -Ph-Z-Ph-, where Ph represents a phenylene group; Z is -O-, -NH-, -CH ₂ -, -SO ₂ -, -C(CH ₃ ) ₂ -, or -C(CF ₃ ) _{2 .)} A and B are hydrogen atoms or methyl groups. ), 2,3-diaminopyridine, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 5,6-diamino-2,3-dicyanopyrazine, 5,6-diamino-2,4-dihydroxypyrimidine, 2,4-diamino-6-dimethylamino-1,3,5-triazine, 1,4-bis(3-aminopropyl)piperazine, 4,4'-[4,4'-propane-1,3-diylbis(piperidine-1,4-diyl)]dianiline, 2,4-diamino-6-isopropoxy-1,3,5-triazine, 2,4-diamino-6-methoxy-1,3,5-triazine, 2,4-diamino-6-phenyl-1,3,5-triazine Azine, 2,4-diamino-6-methyl-1,3,5-triazine, 2,4-diamino-1,3,5-triazine, 4,6-diamino-2-vinyl-1,3,5-triazine, 3,5-diamino-1,2,4-triazole, 6,9-diamino-2-ethoxyacridine lactate, 3,8-diamino-6-phenylphenanthridine, 1,4-diaminopiperazine, 3,6-diaminoacridine, bis(4-aminophenyl)-N-phenylamine, 4,4'-diphenyl-N-methylamine, 4,4'-diaminodiphenylamine, 3,6-diaminocarbazole, 9-methyl-3,6-diaminocarbazole, 9-ethyl-3,6-diaminocarbazole, and diamines represented by the following formula (w1) or (w2).

（Ｓｐは、フェニレン、ピロリジン、ピペリジン、ピペラジン、炭素数２～２０の２価の鎖状炭化水素基、又は該２価の鎖状炭化水素基の－ＣＨ_２－が、－Ｏ－、－ＣＯ－、－ＣＯ－Ｏ－、－ＮＲＣＯ－（Ｒは水素原子又はメチル基を表す。）、－ＮＲＣＯＯ－（Ｒは水素原子又はメチル基を表す。）、－ＣＯＮＲ－（Ｒは水素原子又はメチル基を表す。）、－ＣＯＳ－、－ＮＲ－（Ｒはメチル基を表す。）、ピロリジン、ピペリジン、及びピペラジンから選ばれる基で置換された基を表す。）

(Sp represents phenylene, pyrrolidine, piperidine, piperazine, a divalent chain hydrocarbon group having 2 to 20 carbon atoms, or a group in which -CH ₂ - of the divalent chain hydrocarbon group is substituted with a group selected from -O-, -CO-, -CO-O-, -NRCO- (R represents a hydrogen atom or a methyl group), -NRCOO- (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), -COS-, -NR- (R represents a methyl group), pyrrolidine, piperidine, and piperazine.)

Specific examples of the diamine represented by formula (12) when Y ₉ is a divalent organic group having -NH-CO-NH- in the molecule include diamines represented by formula (13) below, in which A ₁ is -NH-CO-NH-, a group in which at least one of the -CH ₂ - of an alkylene group having 2 to 20 carbon atoms is substituted with -NH-CO-NH-, or a group in which at least one of the -CH _{2 -} of an alkylene group having 2 to 20 carbon atoms is substituted with -NH-CO-NH- and at least one of the other -CH 2 - is substituted with a group selected from -O-, -CO-, -CO-O-, -NRCO- (R represents a hydrogen atom or a methyl group), -NRCOO- (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), -COS-, and -NR- (R represents a methyl group). More preferred specific examples of the diamine include diamines represented by any one of the following formulas (U-1) to (U-9).

（Ａ_１は単結合、－ＮＨ－ＣＯ－ＮＨ－、又は炭素数２～２０のアルキレン基（但し、該アルキレン基の任意の－ＣＨ_２－は、－Ｏ－、－ＣＯ－、－ＣＯ－Ｏ－、－ＮＲＣＯ－（Ｒは水素原子又はメチル基を表す。）、－ＮＲＣＯＯ－（Ｒは水素原子又はメチル基を表す。）、－ＣＯＮＲ－（Ｒは水素原子又はメチル基を表す。）、－ＣＯＳ－、－ＮＲ－（Ｒはメチル基を表す）又は－ＮＨ－ＣＯ－ＮＨ－で置換されていてもよい。）を表す。Ａ_２は、ハロゲン原子、ヒドロキシ基、又は炭素数１～５のアルキル基若しくはアルコキシ基（上記アルキル基若しくはアルコキシ基の任意の水素原子は、ハロゲン原子で置換されていてもよい。）を表す。ａは０～４の整数であり、ａが２以上の場合、Ａ_２は同一でも異なってもよい。ｂ及びｃは、１又は２の整数である。）

(A ₁ represents a single bond, -NH-CO-NH-, or an alkylene group having 2 to 20 carbon atoms (wherein any -CH ₂ - in the alkylene group may be substituted with -O-, -CO-, -CO-O-, -NRCO- (R represents a hydrogen atom or a methyl group), -NRCOO- (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), -COS-, -NR- (R represents a methyl group), or -NH-CO-NH-). _{A 2} represents a halogen atom, a hydroxyl group, or an alkyl or alkoxy group having 1 to 5 carbon atoms (any hydrogen atom in the alkyl or alkoxy group may be substituted with a halogen atom). a represents an integer of 0 to 4, and when a is 2 or more, A ₂ may be the same or different. b and c represent integers of 1 or 2.)

Preferred specific examples of the diamine represented by the above formula (w1) or (w2) include diamines represented by any of the following formulas (n3-1) to (n3-7), and diamines represented by any of the following formulas (n4-1) to (n4-6).

For the purpose of improving printability, diamines having a carboxyl group (COOH group) or a hydroxyl group (OH group) can also be used. Specific examples include 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol, 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, and 3,5-diaminobenzoic acid. Of these, 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, and 3,5-diaminobenzoic acid are preferred. In addition, diamines represented by the following formulas [3b-1] to [3b-4], or diamines in which the amino group is a secondary amino group, can also be used.

In formula [3b-1], Q ¹ represents a single bond, -CH ₂ -, -C ₂ H ₄ -, -C(CH ₃ ) ₂ -, -CF ₂ -, -C(CF ₃ ) ₂ -, -O-, -CO-, -NH-, -N(CH ₃ )-, -CONH-, -NHCO-, -CH ₂ O-, -OCH ₂ -, -COO-, -OCO-, -CON(CH ₃ )- or N(CH ₃ )CO-, m ¹ and m ² each independently represent an integer of 0 to 4, and m ¹ +m ² represents an integer of 1 to 4. In formula [3b-2], m ³ and m ⁴ each independently represent an integer of 1 to 5. In formula [3b-3], Q ² represents a linear or branched alkylene group having 1 to 5 carbon atoms, and m ⁵ represents an integer of 1 to 5. In formula [3b-4], Q ³ and Q ⁴ each independently represent a single bond, -CH ₂ -, -C ₂ H ₄ -, -C(CH ₃ ) ₂ -, -CF ₂ -, -C(CF ₃ ) ₂ -, -O-, -CO-, -NH-, -N(CH ₃ )-, -CONH-, -NHCO-, -CH ₂ O-, -OCH ₂ -, -COO-, -OCO, -CON(CH ₃ )- or -N(CH ₃ )CO-, and m ⁶ represents an integer of 1 to 4.

As the diamine component for obtaining the second polyamic acid, in addition to the above, the diamine used for obtaining the polymer (A) or a known diamine can be used. As the diamine component for obtaining the second polyamic acid, two or more kinds of diamines may be used in combination.

<Methods of producing polyamic acid, polyamic acid ester, and polyimide>
The polyimide precursors, ie, polyamic acid ester, polyamic acid and polyimide, used in the present invention can be produced by known methods such as those described in WO2013/157586.

<Liquid crystal alignment agent>
The liquid crystal aligning agent of the present invention may contain the polymer (A) and, if desired, a second polymer, and further, in addition to these, other polymers such as polyamic acid, polyimide, polyamic acid ester, polyester, polyamide, polyurea, polyorganosiloxane, cellulose derivatives, polyacetal, polystyrene or its derivatives, poly(styrene-phenylmaleimide) derivatives, poly(meth)acrylates, etc.

The liquid crystal alignment agent is used to prepare a liquid crystal alignment film, and takes the form of a coating liquid from the viewpoint of forming a uniform thin film. The liquid crystal alignment agent of the present invention is also preferably a coating liquid containing the above-mentioned polymer component and an organic solvent. In this case, the concentration (content) of the polymer in the liquid crystal alignment agent can be appropriately changed depending on the thickness of the coating film to be formed. From the viewpoint of forming a uniform and defect-free coating film, 1% by mass or more is preferable, and from the viewpoint of storage stability of the solution, 10% by mass or less is preferable. A particularly preferable polymer concentration is 2 to 8% by mass.

The organic solvent contained in the liquid crystal alignment agent is not particularly limited as long as it is a solvent (also called a good solvent) in which the polymer component dissolves uniformly. Specific examples include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylsulfoxide, γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, etc. Among them, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, or γ-butyrolactone is preferred. The good solvent preferably accounts for 20 to 99% by mass of the total solvent contained in the liquid crystal alignment agent, more preferably 20 to 90% by mass, and particularly preferably 30 to 80% by mass.

In addition, the organic solvent contained in the liquid crystal alignment agent is preferably a mixed solvent that uses a solvent (also called a poor solvent) that improves the coating property and the surface smoothness of the coating film when applying the liquid crystal alignment agent in addition to a good solvent. Specific examples of the poor solvent are listed below, but are not limited to these examples.
For example, diisopropyl ether, diisobutyl ether, diisobutyl carbinol (2,6-dimethyl-4-heptanol), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, propylene glycol monobutyl ether, 1-(2-butoxyethoxy)-2-propanol, 2-(2-butoxyethoxy) 1-propanol, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monobutyl ether acetate, ethylene glycol monoacetate, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethylene glycol acetate, propylene glycol diacetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, n-butyl lactate, isoamyl lactate, diethylene glycol monoethyl ether, diisobutyl ketone (2,6-dimethyl-4-heptanone), and the like.

Among the poor solvents, diisobutyl carbinol, propylene glycol monobutyl ether, propylene glycol diacetate, diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, and diisobutyl ketone are preferred.

Preferred solvent combinations of good and poor solvents include N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone and propylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and diethylene glycol diethyl ether, and N-methyl-2-pyrrolidone and γ-butyrolactone. Examples of the poor solvent include 1 to 80% by mass of the total solvent contained in the liquid crystal alignment agent, more preferably 10 to 80% by mass, and particularly preferably 20 to 70% by mass. The type and content of such a solvent are appropriately selected depending on the coating device, coating conditions, and coating environment of the liquid crystal alignment agent.

The liquid crystal alignment agent of the present invention may contain additional components other than the polymer component and the organic solvent. Such additional components include adhesion aids for improving the adhesion between the liquid crystal alignment film and the substrate or between the liquid crystal alignment film and the sealant, compounds for increasing the strength of the liquid crystal alignment film (hereinafter also referred to as cross-linking compounds), dielectrics and conductive substances for adjusting the dielectric constant and electrical resistance of the liquid crystal alignment film, etc.

（Ｒ_７１は、水素原子、炭素数１～３のアルキル基又は「＊－ＣＨ_２－ＯＨ」である。Ｒ_７２及びＲ_７３は、それぞれ独立に水素原子、炭素数１～３のアルキル基又は「＊－ＣＨ_２－ＯＨ」である。＊は結合手を示す。Ａは芳香環を有する（ｍ＋ｎ）価の有機基を表す。ｍは１～６の整数を表し、ｎは０～４の整数を表す。） As the crosslinkable compound, from the viewpoints of generating less AC afterimages and having a high effect of improving film strength, a compound having at least one group selected from the group consisting of an oxiranyl group, an oxetanyl group, a protected isocyanate group, a protected isothiocyanate group, a group containing an oxazoline ring structure, a group containing a Meldrum's acid structure, a cyclocarbonate group, and a group represented by the following formula (d), or a compound represented by the following formula (e) (hereinafter these are also collectively referred to as compound (C)).

(R ₇₁ is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH ₂ -OH". R ₇₂ and R ₇₃ are each independently a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH ₂ -OH". * represents a bond. A represents an (m+n)-valent organic group having an aromatic ring. m represents an integer of 1 to 6, and n represents an integer of 0 to 4.)

Specific examples of the compound having an oxiranyl group include compounds having two or more oxiranyl groups, such as the compounds described in [0037] of JP-A-10-338880 and compounds having a triazine ring skeleton described in WO2017/170483. Among these, compounds containing nitrogen atoms, such as N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, N,N,N',N'-tetraglycidyl-p-phenylenediamine, and compounds represented by any of the following formulas (r-1) to (r-3), are particularly preferred.

Specific examples of compounds having an oxetanyl group include compounds having two or more oxetanyl groups described in paragraphs [0170] to [0175] of WO2011/132751.

Specific examples of the compound having a protected isocyanate group include compounds having two or more protected isocyanate groups described in [0046] to [0047] of JP 2014-224978 A, and compounds having three or more protected isocyanate groups described in [0119] to [0120] of WO 2015/141598 A. Among these, compounds represented by any of the following formulae (bi-1) to (bi-3) are preferred.

Specific examples of compounds having a protected isothiocyanate group include compounds having two or more protected isothiocyanate groups described in JP 2016-200798 A.
Specific examples of the compound having a group containing an oxazoline ring structure include compounds containing two or more oxazoline structures described in paragraph [0115] of JP-A-2007-286597.

Specific examples of the compound having a group containing a Meldrum's acid structure include compounds having two or more Meldrum's acid structures described in WO2012/091088.
Specific examples of the compound having a cyclocarbonate group include the compounds described in WO2011/155577.
Examples of the alkyl group having 1 to 3 carbon atoms for R ₁ , R ₂ and R ₃ in the group represented by formula (d) above include a methyl group, an ethyl group and a propyl group.

Specific examples of compounds having a group represented by the above formula (d) include compounds having two or more groups represented by the above formula (d) described in WO2015/072554 and JP 2016-118753 [0058], and compounds described in JP 2016-200798. Among these, compounds represented by any of the following formulas (hd-1) to (hd-8) are preferred.

Examples of the (m+n)-valent organic group having an aromatic ring in A of the above formula (e) include an (m+n)-valent aromatic hydrocarbon group having 5 to 30 carbon atoms, an (m+n)-valent organic group to which an aromatic hydrocarbon group having 5 to 30 carbon atoms is bonded directly or via a linking group, and an (m+n)-valent group having an aromatic heterocycle. Examples of the aromatic hydrocarbon group include benzene and naphthalene. Examples of the aromatic heterocycle include a pyrrole ring, an imidazole ring, a pyrazole ring, a pyridine ring, a pyrimidine ring, a quinoline ring, an isoquinoline ring, a carbazole ring, a pyridazine ring, a pyrazine ring, a benzimidazole ring, a benzimidazole ring, an indole ring, a quinoxaline ring, and an acridine ring. Examples of the linking group include an alkylene group having 1 to 10 carbon atoms, a group obtained by removing one hydrogen atom from the alkylene group, and a divalent or trivalent cyclohexane ring. Any hydrogen atom in the alkylene group may be substituted with a fluorine atom or an organic group such as a trifluoromethyl group. Specific examples include the compounds described in WO2010/074269. Preferred specific examples include any of the following formulas (e-1) to (e-9).

The above compounds are examples of crosslinkable compounds, and are not limited thereto. For example, the components other than those described above disclosed in [0105] to [0116] of WO2015/060357 can be mentioned. In addition, the crosslinkable compounds contained in the liquid crystal aligning agent of the present invention may be combined in two or more kinds.
The content of the crosslinkable compound in the liquid crystal aligning agent of the present invention is preferably 0.5 to 20 parts by mass relative to 100 parts by mass of the polymer component contained in the liquid crystal aligning agent, and more preferably 1 to 15 parts by mass from the viewpoints of proceeding with the crosslinking reaction to exhibit the intended effect and reducing the occurrence of AC afterimages.

Examples of the adhesion aids include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethyl N-trimethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3- Aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis(oxyethylene)-3-aminopropyltrimethoxysilane, N-bis(oxyethylene)-3-aminopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane Examples of silane coupling agents include silane coupling agents such as xysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, tris-(trimethoxysilylpropyl)isocyanurate, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-isocyanatepropyltriethoxysilane. The amount of these silane coupling agents used is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, per 100 parts by mass of the polymer component contained in the liquid crystal alignment agent, from the viewpoint of reducing the occurrence of AC afterimages.

<Method of manufacturing liquid crystal alignment film>
The liquid crystal alignment film using the liquid crystal aligning agent of the present invention can be produced by using the above-mentioned liquid crystal aligning agent of the present invention by a known method for obtaining a liquid crystal alignment film from a liquid crystal aligning agent.
In particular, a liquid crystal alignment film using the liquid crystal aligning agent of the present invention can be efficiently produced by sequentially carrying out the following steps (1), (2), (3), and preferably the step (4).

<Step (1)>
This is a process of applying the liquid crystal alignment agent of the present invention onto a substrate. The substrate to which the liquid crystal alignment agent is applied is not particularly limited as long as it is a highly transparent substrate, and glass substrates, silicon nitride substrates, plastic substrates such as acrylic substrates and polycarbonate substrates, etc. can also be used. In this case, it is preferable to use a substrate on which an ITO electrode for driving the liquid crystal is formed in terms of simplifying the process. In addition, in a reflective liquid crystal display element, one of the substrates can be an opaque one such as a silicon wafer, and in this case, a light-reflecting material such as aluminum can also be used for the electrode.
Industrially, the liquid crystal alignment agent is generally applied by screen printing, offset printing, flexographic printing, inkjet printing, etc. Other application methods include a dip method, a roll coater method, a slit coater method, a spinner method, a spray method, etc., and these may be used depending on the purpose.

<Step (2)>
Step (2) is a step of heating the coating film of the liquid crystal alignment agent obtained in step (1). After the liquid crystal alignment agent is applied onto the substrate, the solvent can be evaporated or the amic acid or amic acid ester in the polymer can be thermally imidized by a heating means such as a hot plate, a heat circulation type oven, or an IR (infrared) type oven. The drying and baking steps after the application of the liquid crystal alignment agent can be performed at any temperature and time, and may be performed multiple times. The temperature for removing the organic solvent of the liquid crystal alignment agent can be, for example, 40 to 150°C. From the viewpoint of shortening the process, it may be performed at 40 to 120°C. The baking time is not particularly limited, but may be 1 to 10 minutes or 1 to 5 minutes. When the amic acid or amic acid ester in the polymer is thermally imidized, the polymer can be baked at, for example, 190 to 250°C or 200 to 240°C after the step of removing the organic solvent. The baking time is not particularly limited, but may be 5 to 40 minutes or 5 to 30 minutes.

<Step (3)>
Step (3) is a step of irradiating the film obtained in step (2) with polarized ultraviolet light. The wavelength of the ultraviolet light is preferably 200 to 400 nm, more preferably 200 to 300 nm. In order to improve the liquid crystal alignment, the substrate coated with the liquid crystal alignment film may be irradiated with ultraviolet light while being heated at 50 to 250°C. The radiation dose is preferably 1 to 10,000 mJ/ ^cm2 , more preferably 100 to 5,000 mJ/ ^cm2 . The liquid crystal alignment film thus prepared can stably align liquid crystal molecules in a certain direction.
The higher the extinction ratio of the polarized UV light, the higher the anisotropy that can be imparted, which is preferable. Specifically, the extinction ratio of the linearly polarized UV light is preferably 10:1 or more, and more preferably 20:1 or more.

<Step (4)>
Step (4) is a step of baking the film obtained in step (3) at 100° C. or higher and at a temperature higher than that in step (2). The baking temperature is not particularly limited as long as it is 100° C. or higher and higher than the baking temperature in step (2), but is preferably 150 to 300° C., more preferably 150 to 250° C., and even more preferably 200 to 250° C. The baking time is preferably 5 to 120 minutes, more preferably 5 to 60 minutes, and even more preferably 5 to 30 minutes.
The thickness of the liquid crystal alignment film after baking is preferably 5 to 300 nm, more preferably 10 to 200 nm, since if it is too thin, the reliability of the liquid crystal display element may decrease.

Furthermore, after carrying out either the above step (3) or (4), the obtained liquid crystal alignment film can be subjected to a contact treatment using water and/or a solvent.
The solvent used in the contact treatment is not particularly limited as long as it dissolves the decomposition product generated from the liquid crystal alignment film by irradiation with ultraviolet light. Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, and cyclohexyl acetate. Among these, water, 2-propanol, 1-methoxy-2-propanol, and ethyl lactate are preferred from the viewpoint of versatility and solvent safety. Water, 1-methoxy-2-propanol, and ethyl lactate are more preferred. Two or more types of solvents may be combined.

The above-mentioned contact treatment, i.e., the method of treating the liquid crystal alignment film irradiated with polarized ultraviolet light with water or a solvent, includes immersion treatment and spray treatment (also called spray treatment). The treatment time in these treatments is preferably 10 seconds to 1 hour in order to efficiently dissolve the decomposition products generated from the liquid crystal alignment film by the ultraviolet light. Of these, immersion treatment for 1 to 30 minutes is preferable. The solvent during the above-mentioned contact treatment may be at room temperature or heated, but is preferably 10 to 80°C. Of these, 20 to 50°C is preferable. In addition, ultrasonic treatment or the like may be performed as necessary in terms of the solubility of the decomposition products.

After the contact treatment, it is preferable to rinse the liquid crystal alignment film with a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone, or methyl ethyl ketone, or to bake the liquid crystal alignment film. Either rinsing or baking may be performed, or both may be performed. The baking temperature is preferably 150 to 300°C, more preferably 180 to 250°C, and more preferably 200 to 230°C. The baking time is preferably 10 seconds to 30 minutes, and more preferably 1 to 10 minutes.

The liquid crystal alignment film of the present invention is suitable as a liquid crystal alignment film for a liquid crystal display element of a horizontal electric field type such as an IPS type or an FFS type, and is particularly useful as a liquid crystal alignment film for a liquid crystal display element of an FFS type. The liquid crystal display element is obtained by preparing a liquid crystal cell by a known method after obtaining a substrate with a liquid crystal alignment film obtained from a liquid crystal alignment agent, and using the liquid crystal cell.
As an example of a method for fabricating a liquid crystal cell, a liquid crystal display element having a passive matrix structure will be described below. However, a liquid crystal display element having an active matrix structure in which a switching element such as a TFT (Thin Film Transistor) is provided in each pixel portion constituting an image display may also be used.

Specifically, transparent glass substrates are prepared, and a common electrode is provided on one substrate, and a segment electrode is provided on the other substrate. These electrodes may be, for example, ITO electrodes, and are patterned to display a desired image. Next, an insulating film is provided on each substrate so as to cover the common electrode and the segment electrodes. The insulating film may be, for example, a SiO ₂ -TiO ₂ film formed by a sol-gel method.
Next, a liquid crystal alignment film is formed on each substrate, and one substrate is superimposed on the other substrate so that the liquid crystal alignment film faces each other, and the periphery is bonded with a sealant. In order to control the gap between the substrates, a spacer is usually mixed into the sealant, and it is also preferable to scatter spacers for controlling the gap between the substrates on the inner surface where the sealant is not provided. An opening is provided in a part of the sealant, through which liquid crystal can be filled from the outside. Next, a liquid crystal material is injected into the space surrounded by the two substrates and the sealant through the opening provided in the sealant, and then the opening is sealed with an adhesive. For the injection, a vacuum injection method or a method utilizing capillary action in the atmosphere may be used. The liquid crystal material may be either a positive type liquid crystal material or a negative type liquid crystal material. Next, a polarizing plate is installed. Specifically, a pair of polarizing plates is attached to the surface of the two substrates opposite to the liquid crystal layer.

As described above, by using the manufacturing method of the present invention, it is possible to suppress image retention caused by long-term AC driving in liquid crystal display elements using the IPS driving method or FFS driving method. Furthermore, by removing the organic solvent at 40 to 150°C in step (2) and then performing step (3), a liquid crystal alignment film can be obtained with fewer steps than in the past. The liquid crystal alignment agent of the present invention can be particularly preferably used in a manufacturing method for a liquid crystal alignment film that includes a step of removing the organic solvent at 40 to 150°C in step (2) and then performing step (3).

As described above, by using the liquid crystal alignment agent of the present invention, it is possible to obtain a liquid crystal alignment film with high sealing adhesion and with little residual DC-derived afterimage or AC afterimage. In particular, it is possible to obtain a liquid crystal display element with excellent contrast in which the variation in brightness within the plane during black display is suppressed, and a liquid crystal display element with good display quality can be obtained.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto. The abbreviations of compounds and the measuring methods of each property are as follows.
(solvent)
NMP: N-methyl-2-pyrrolidone, GBL: γ-butyrolactone,
BCS: butyl cellosolve,
(Diamine)
DA-1 to DA-4: Compounds represented by the following formulas (DA-1) to (DA-4), respectively:
(Tetracarboxylic acid dianhydride)
CA-1 and CA-2: Compounds (additives) represented by the following formulas (CA-1) and (CA-2), respectively.
C-1: Compound represented by the following formula (C-1) C-2: 2,2'-bis(4-hydroxy-3,5-dihydroxymethylphenyl)propane S-1: Compound represented by the following formula (S-1),

<Measurement of Viscosity>
The measurement was performed at 25° C. using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample volume of 1.1 mL and a cone rotor TE-1 (1°34′, R24).

<Measurement of imidization rate>
20 mg of polyimide powder was placed in an NMR sample tube (NMR sampling tube standard, φ5 (Kusano Scientific Co., Ltd.)), deuterated dimethyl sulfoxide (DMSO-d6, 0.05% TMS (tetramethylsilane) mixture) (0.53 mL) was added, and the mixture was sonicated to completely dissolve. This solution was measured for proton NMR at 500 MHz using an NMR measurement device (JNW-ECA500) (JEOL Datum Co., Ltd.). The imidization rate was calculated by the following formula, using a proton derived from a structure that does not change before and after imidization as a reference proton, and the peak integrated value of this proton and the proton peak integrated value derived from the NH group of the amic acid that appears around 9.5 ppm to 10.0 ppm.
Imidization rate (%)=(1−α·x/y)×100
In the above formula, x is the integrated value of the proton peak derived from the NH group of the amic acid, y is the integrated value of the peak of the reference proton, and α is the ratio of the number of reference protons to one NH group proton of the amic acid in the case of polyamic acid (imidization rate 0%).

[Polymer synthesis example]
Examples of synthesizing polyamic acid and polyimide are shown below, where PI stands for polyimide.

<Synthesis Example 1>
7.33 g (0.03 mol) of DA-1 was weighed out into a 200 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, 99.1 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. 6.19 g (0.028 mol) of CA-1 was added while stirring this diamine solution, and the mixture was stirred at 40° C. for 24 hours to obtain a polyamic acid solution (A-1) (viscosity: 107 mPa s).

<Synthesis Example 2>
4.10 g (0.0168 mol) of DA-1 and 8.32 g (0.0392 mol) of DA-3 were weighed out into a 200 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, 176 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. 11.6 g (0.0518 mol) of CA-1 was added while stirring this diamine solution, and the mixture was stirred at 40° C. for 24 hours to obtain a polyamic acid solution (A-2) (viscosity: 219 mPa s).

<Synthesis Example 3>
6.37 g (0.03 mol) of DA-3 was weighed out into a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, 92.3 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. 6.22 g (0.0278 mol) of CA-1 was added while stirring this diamine solution, and the mixture was stirred at 40° C. for 24 hours to obtain a polyamic acid solution (A-3) (viscosity: 347 mPa s).

<Synthesis Example 4>
2.05 g (0.0084 mol) of DA-1 and 4.16 g (0.0196 mol) of DA-3 were weighed out into a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, 88.6 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. 5.52 g (0.0246 mol) of CA-1 and 0.35 g (0.0014 mol) of CA-2 were added while stirring this diamine solution, and the mixture was stirred at 40° C. for 24 hours to obtain a polyamic acid solution (A-4) (viscosity: 213 mPa s).

<Synthesis Example 5>
3.23 g (0.0084 mol) of DA-2 and 4.16 g (0.0196 mol) of DA-3 were weighed out into a 200 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, 97.3 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. 5.52 g (0.0246 mol) of CA-1 and 0.35 g (0.0014 mol) of CA-2 were added while stirring this diamine solution, and the mixture was stirred at 40° C. for 24 hours to obtain a polyamic acid solution (A-5) (viscosity: 198 mPa s).

<Synthesis Example 6>
In a 200 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, 1.37 g (0.0056 mol) of DA-1, 4.16 g (0.0196 mol) of DA-3, and 1.56 g (0.0028 mol) of DA-4 were weighed out, 95.1 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring this diamine solution, 5.52 g (0.0246 mol) of CA-1 and 0.35 g (0.0014 mol) of CA-2 were added, and the mixture was stirred at 40° C. for 24 hours to obtain a polyamic acid solution (A-6) (viscosity: 224 mPa·s).

<Synthesis Example 7>
In a 200 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, 1.37 g (0.0056 mol) of DA-1, 4.16 g (0.0196 mol) of DA-3, and 1.56 g (0.0028 mol) of DA-4 were weighed out, 95.3 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring this diamine solution, 5.21 g (0.0232 mol) of CA-1 and 0.700 g (0.0028 mol) of CA-2 were added, and the mixture was stirred at 40° C. for 24 hours to obtain a polyamic acid solution (A-7) (viscosity: 177 mPa s).

<Synthesis Example 8>
In a 200 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, 1.37 g (0.0056 mol) of DA-1, 4.16 g (0.0196 mol) of DA-3, and 1.56 g (0.0028 mol) of DA-4 were weighed out, 95.6 g of NMP was added, and the mixture was stirred and dissolved while feeding nitrogen. While stirring this diamine solution, 4.90 g (0.0218 mol) of CA-1 and 1.05 g (0.0042 mol) of CA-2 were added, and the mixture was stirred at 40° C. for 24 hours to obtain a polyamic acid solution (A-8) (viscosity: 176 mPa s).

<Synthesis Example 9>
35 g (0.0093 mol) of the obtained polyamic acid solution (A-1) was taken in a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, 11.7 g of NMP was added, and the mixture was stirred for 30 minutes. 2.84 g of acetic anhydride (3 equivalents relative to the molar amount of polyamic acid) and 0.73 g of pyridine (equivalent to the molar amount of polyamic acid) were added to the obtained polyamic acid solution, and the mixture was heated at 50°C for 3 hours to perform chemical imidization. The obtained reaction solution was poured into 150 ml of methanol while stirring, and the precipitate was filtered out. The same operation was carried out twice to wash the resin powder, and then the resin powder was dried at 60°C for 12 hours to obtain a polyimide resin powder. The imidization rate of this polyimide resin powder was 71%. 3.60 g of the obtained polyimide resin powder was placed in a 100 ml Erlenmeyer flask, 26.4 g of NMP was added so that the solid concentration was 12%, and the mixture was stirred at 70° C. for 24 hours to dissolve the polyimide resin, thereby obtaining a polyimide solution (A-1-PI).

<Synthesis Examples 10 to 16>
The same procedures as in Synthesis Example 9 were used except that the raw materials shown in Table 1 below were used. The specifications of the polyimides obtained in Synthesis Examples 10 to 16 are shown in Table 1 together with those of Synthesis Example 9.

The numbers in parentheses in Table 1 indicate, for the tetracarboxylic acid components, the blending ratio (parts by mole) of each compound relative to 100 parts by mole of the total amount of tetracarboxylic acid derivatives used in the synthesis, and for the diamine components, the blending ratio (parts by mole) of each compound relative to 100 parts by mole of the total amount of diamines used in the synthesis. For the organic solvents, the blending ratio (parts by mass) of each organic solvent relative to 100 parts by mass of the total amount of organic solvents contained in the polyamic acid solution or polyimide solution is indicated.

[Preparation of liquid crystal alignment agent]
<Comparative Example 1>
7.5 g of polyimide solution (A-1-PI) was weighed out into a 20 ml sample tube containing a stirrer, 2.23 g of NMP, 5.10 g of GBL, 4.0 g of BCS, 0.90 g of GBL solution containing 1 wt% of S-1, and 0.27 g of NMP solution containing 10 wt% of C-1 were added, and stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal alignment agent (R1).

Example 1
In a 20 ml sample tube containing a stirrer, 7.5 g of polyimide solution (A-4-PI) was taken, 2.23 g of NMP, 5.10 g of GBL, 4.0 g of BCS, 0.90 g of GBL solution containing 1 wt% of S-1, and 0.27 g of NMP solution containing 10 wt% of C-1 were added, and the mixture was stirred with a magnetic stirrer for 30 minutes to obtain a liquid crystal alignment agent (1).

<Examples 2 to 6, Comparative Example 3>
In Examples 2 to 6 and Comparative Example 3, each liquid crystal alignment agent was obtained in the same manner as in Comparative Example 1 and Example 1, except that each polyimide solution, additive, and organic solvent listed in the following Table 2 were used. The specifications of each obtained liquid crystal alignment agent are shown in Table 1 together with the liquid crystal alignment agents of Example 1 and Comparative Example 1.

括弧内の数値は、液晶配向剤の合計量１００質量部に対する各成分の配合割合(質量％)を表す。

The numbers in parentheses indicate the blending ratio (mass %) of each component relative to 100 parts by mass of the total amount of the liquid crystal alignment agent.

<Preparation of Liquid Crystal Display Element>
A substrate with electrodes was prepared. The substrate was a glass substrate with a size of 30 mm x 35 mm and a thickness of 0.7 mm. An IZO electrode having a solid pattern, which constitutes an opposing electrode as a first layer, was formed on the substrate. A SiN (silicon nitride) film formed by a CVD method was formed as a second layer on the opposing electrode of the first layer. The thickness of the SiN film of the second layer was 500 nm, and it functions as an interlayer insulating film. A comb-shaped pixel electrode formed by patterning an IZO film as a third layer was arranged on the SiN film of the second layer, forming two pixels, a first pixel and a second pixel. The size of each pixel was 10 mm in length and about 5 mm in width. At this time, the opposing electrode of the first layer and the pixel electrode of the third layer were electrically insulated by the action of the SiN film of the second layer.

The pixel electrode in the third layer has a comb-like shape consisting of multiple electrode elements arranged in a "L" shape with a bent central portion. The width of each electrode element in the short direction is 3 μm, and the distance between the electrode elements is 6 μm. Because the pixel electrodes that form each pixel are arranged in multiple electrode elements arranged in a "L" shape with a bent central portion, the shape of each pixel is not rectangular, but has a shape similar to a bold "L" shape that is bent in the center like the electrode elements. Each pixel is divided into upper and lower parts by the bent central portion, and has a first region above the bent portion and a second region below the bent portion.

A liquid crystal alignment agent filtered through a filter with an average pore size of 1.0 μm was applied by spin coating to the respective surfaces of the above-mentioned electrode-attached substrate and a glass substrate having a columnar spacer with a height of 4 μm and an ITO film formed on the back surface, and dried for 2 minutes on a hot plate at 80° C. Thereafter, the coating surface was irradiated with 150 to 350 mJ/ ^cm2 of linearly polarized ultraviolet light with an extinction ratio of 26:1 and a wavelength of 254 nm through a polarizing plate, and then baked for 30 minutes in a hot air circulation oven at 230° C. to obtain each substrate with a liquid crystal alignment film with a thickness of 100 nm.
Next, a sealant was printed on one of the pair of glass substrates with liquid crystal alignment film, and the other substrate was attached so that the liquid crystal alignment film faces each other, and the sealant was cured to prepare an empty cell. Liquid crystal MLC-3019 (Merck) was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an FFS drive liquid crystal cell. The obtained liquid crystal cell was then heated at 120°C for 1 hour and left overnight before being used for evaluation.

[evaluation]
<Evaluation of Liquid Crystal Alignment>
Using liquid crystal cells before the ISO treatment, those with initial flow alignment were rated as "bad" and those without initial flow alignment were rated as "good".

<Evaluation of Seal Adhesion>
[Sample preparation]
The liquid crystal alignment agent prepared above was applied by spin coating to a 30 mm x 40 mm ITO substrate. After drying for 2 minutes on a hot plate at 80 ° C, the coating surface was irradiated with 254 nm ultraviolet light through a polarizing plate, and then baked for 20 minutes in a hot air circulation oven at 230 ° C to form a coating film with a thickness of 100 nm. Two substrates obtained in this way were prepared, and 4 μm bead spacers were applied to the liquid crystal alignment film surface of one substrate, and then a sealant (XN-1500T manufactured by Kyoritsu Chemical Industry Co., Ltd.) was dropped. Next, the liquid crystal alignment film surface of the other substrate was placed inside, and the substrates were laminated so that the overlap width was 1 cm. At that time, the amount of the sealant dropped was adjusted so that the diameter of the sealant after lamination was 3 mm. The two laminated substrates were fixed with clips, and then thermally cured at 150 ° C for 1 hour to prepare a sample for adhesion evaluation.

[Measurement of Seal Adhesion]
The sample substrates prepared above were fixed at the ends of the upper and lower substrates using a bench-top precision universal testing machine (AGS-X 500N, manufactured by Shimadzu Corporation), and the substrates were pressed from the top of the center to measure the strength (N) at which they peeled off. This peel strength (N) was normalized by the adhesive area ( ^mm2 ) to give the seal adhesion (N/ ^mm2 ) for each sample. If the seal adhesion was greater than 4 N/ ^mm2 , it was evaluated as "good". If it was less than 4 ^N / ^mm2 , it was evaluated as "poor".

The liquid crystal aligning agent of the present invention is useful for forming a liquid crystal alignment film in a wide range of liquid crystal display elements such as those of the IPS driving system and the FFS driving system.
In addition, the entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2019-034305 filed on February 27, 2019 are hereby incorporated by reference as the disclosure of the specification of the present invention.

Claims (30)

A liquid crystal aligning agent comprising a polymer (A) having a repeating unit represented by the following formula (3) and a repeating unit represented by the following formula (5),
The liquid crystal aligning agent, wherein the polymer (A) is a polyimide having an imidization rate of 71% or more.

(R ₃₁ to R ₃₄ in formula (3) are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group, and may be the same or different, but at least one of R ₃₁ to R ₃₄ represents a group other than a hydrogen atom as defined above. Y ₃ represents a divalent organic group represented by the following formula (I).)

(* represents a bond.)

(R ₅₁ to R ₅₄ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group, and may be the same or different, but at least one of R ₅₁ to R ₅₄ represents a group other than a hydrogen atom as defined above. Y ₅ each independently represents a divalent organic group having a partial structure represented by the following formula (J-1), or a divalent organic group represented by the following formula (J-2).)

(Q ₅ is a single bond, -(CH ₂ ) _n - (n is an integer of 1 to ₂₀ ), or a group which can be replaced by -O-, -COO-, -OCO-, -NQ _{9 -, -NQ 9 CO-, -CONQ 9 -, -NQ 9 CONQ 10 -, -NQ 9 COO-, or -OCOO-, provided that any -CH 2 - in - ( CH 2 )} n - are not adjacent to each other. _{Q 9 and} Q ₁₀ each independently represent a hydrogen atom or a monovalent organic group. Q ₆ and Q ₇ each independently represent -H, -NHD, -N(D) ₂ , a group having -NHD, or a group having -N(D) ₂ . _{Q 8} is -NHD, -N(D) ₂ , a group having -NHD, or -N(D) _2. D represents a carbamate protecting group. However, at least one of Q ₅ , Q ₆ and Q ₇ has a carbamate protecting group in the group. *1 represents a bond. 2. The liquid crystal aligning agent according to claim 1, wherein said Q ₅ is a group which can be replaced by -NQ ₉ -, -NQ ₉ CO-, or -CONQ ₉ -, provided that any -CH ₂ - of (CH ₂ ) _n - are not adjacent to each other. The liquid crystal aligning agent according to claim 1 or 2, further comprising at least one group selected from the group consisting of an oxiranyl group, an oxetanyl group, a protected isocyanate group, a protected isothiocyanate group, a group containing an oxazoline ring structure, a group containing a Meldrum's acid structure, a cyclocarbonate group, and a group represented by the following formula (d), or a compound represented by the following formula (e).

(R ₇₁ is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH ₂ -OH". R ₇₂ and R ₇₃ are each independently a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH ₂ -OH". * represents a bond. A represents an (m+n)-valent organic group having an aromatic ring. m represents an integer of 1 to 6, and n represents an integer of 0 to 4.) The liquid crystal alignment agent according to any one of claims 1 to 3, which obtains a liquid crystal alignment film having a seal adhesion of more than 4 N/ ^mm2 . A liquid crystal aligning agent comprising a polymer (A) having a repeating unit represented by the following formula (3) and a repeating unit represented by the following formula (5),
The liquid crystal alignment agent, which provides a liquid crystal alignment film having a seal adhesion of more than 4 N/ ^mm2 .

(R ₃₁ to R ₃₄ in formula (3) are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group, and may be the same or different, but at least one of R ₃₁ to R ₃₄ represents a group other than a hydrogen atom as defined above. Y ₃ represents a divalent organic group represented by the following formula (I).)

(* represents a bond.)

(R ₅₁ to R ₅₄ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group, and may be the same or different, but at least one of R ₅₁ to R ₅₄ represents a group other than a hydrogen atom as defined above. Each Y ₅ independently represents a divalent organic group having a partial structure represented by the following formula (J-1).)

(Q ₅ is a single bond, -(CH ₂ ) _n - (n is an integer of 1 to 20), or a group which can be replaced with -O-, -COO-, -OCO-, -NQ ₉ CO-, -CONQ ₉ -, -NQ ₉ COO-, or -OCOO-, provided that any -CH ₂ - in -(CH ₂ ) _n - are not adjacent to each other. Q ₉ each independently represents a hydrogen atom or a monovalent organic group. Q ₆ and Q ₇ each independently represent -H, -NHD, -N(D) ₂ , a group having -NHD, or a group having -N(D) _2. D represents a carbamate protecting group, with the proviso that at least one of Q ₅ , Q ₆ , and Q ₇ has a carbamate protecting group in the group. *1 represents a bond.) 6. The liquid crystal aligning agent according to claim 5, wherein said Q ₅ is a group which can be replaced by -NQ ₉ CO- or -CONQ ₉ -, provided that any -CH ₂ - of (CH ₂ ) _n - are not adjacent to each other. Further, the liquid crystal aligning agent according to any one of claims 5 to 6, which contains at least one group selected from the group consisting of an oxiranyl group, an oxetanyl group, a protected isocyanate group, a protected isothiocyanate group, a group containing an oxazoline ring structure, a group containing a Meldrum's acid structure, a cyclocarbonate group, and a group represented by the following formula (d), or a compound represented by the following formula (e).

(R ₇₁ is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH ₂ -OH". R ₇₂ and R ₇₃ are each independently a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH ₂ -OH". * represents a bond. A represents an (m+n)-valent organic group having an aromatic ring. m represents an integer of 1 to 6, and n represents an integer of 0 to 4.) A liquid crystal alignment film comprising a polymer (A) obtained from the liquid crystal alignment agent according to any one of claims 1 to 4 and having a repeating unit represented by the following formula (3) and a repeating unit represented by the following formula (5):

(R ₃₁ to R ₃₄ in formula (3) are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group, and may be the same or different, but at least one of R ₃₁ to R ₃₄ represents a group other than a hydrogen atom as defined above. Y ₃ represents a divalent organic group represented by the following formula (I).)

(* represents a bond.)

(R ₅₁ to R ₅₄ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group, and may be the same or different, but at least one of R ₅₁ to R ₅₄ represents a group other than a hydrogen atom as defined above. Y ₅ each independently represents a divalent organic group having a partial structure represented by the following formula (J-1), or a divalent organic group represented by the following formula (J-2).)

(Q ₅ is a single bond, -(CH ₂ ) _n - (n is an integer of 1 to ₂₀ ), or a group which can be replaced by -O-, -COO-, -OCO-, -NQ _{9 -, -NQ 9 CO-, -CONQ 9 -, -NQ 9 CONQ 10 -, -NQ 9 COO-, or -OCOO-, provided that any -CH 2 - in - ( CH 2 )} n - are not adjacent to each other. _{Q 9 and} Q ₁₀ each independently represent a hydrogen atom or a monovalent organic group. Q ₆ and Q ₇ each independently represent -H, -NHD, -N(D) ₂ , a group having -NHD, or a group having -N(D) ₂ . _{Q 8} is -NHD, -N(D) ₂ , a group having -NHD, or -N(D) _2. D represents a carbamate-based protecting group to be eliminated. However, at least one of Q ₅ , Q ₆ and Q ₇ has a carbamate-based protecting group in the group. *1 represents a bond. 9. The liquid crystal alignment film according to claim 8, wherein said Q ₅ is a group which can be replaced by -NQ ₉ -, -NQ ₉ CO-, or -CONQ ₉ -, provided that any -CH ₂ - of (CH ₂ ) _n - are not adjacent to each other. The liquid crystal alignment film according to claim 8 or 9, wherein the polymer (A) is a polyimide having an imidization rate of 71% or more. Further, a compound having at least one group selected from the group consisting of an oxiranyl group, an oxetanyl group, a protected isocyanate group, a protected isothiocyanate group, a group containing an oxazoline ring structure, a group containing a Meldrum's acid structure, a cyclocarbonate group, and a group represented by the following formula (d), or a compound represented by the following formula (e) (hereinafter, these are also collectively referred to as compound (C)). The liquid crystal alignment film according to any one of claims 8 to 10.

(R ₇₁ is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH ₂ -OH". R ₇₂ and R ₇₃ are each independently a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH ₂ -OH". * represents a bond. A represents an (m+n)-valent organic group having an aromatic ring. m represents an integer of 1 to 6, and n represents an integer of 0 to 4.) The liquid crystal alignment film according to any one of claims 8 to 11, having a seal adhesion of more than 4 N/ ^mm2 . A liquid crystal alignment film comprising a polymer (A) obtained from the liquid crystal alignment agent according to any one of claims 5 to 7 and having a repeating unit represented by the following formula (3) and a repeating unit represented by the following formula (5):

(R ₃₁ to R ₃₄ in formula (3) are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group, and may be the same or different, but at least one of R ₃₁ to R ₃₄ represents a group other than a hydrogen atom as defined above. Y ₃ represents a divalent organic group represented by the following formula (I).)

(* represents a bond.)

(R ₅₁ to R ₅₄ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group, and may be the same or different, but at least one of R ₅₁ to R ₅₄ represents a group other than a hydrogen atom as defined above. Each Y ₅ independently represents a divalent organic group having a partial structure represented by the following formula (J-1).)

(Q ₅ is a single bond, -(CH ₂ ) _n - (n is an integer of 1 to 20), or a group which can be replaced with -O-, -COO-, -OCO-, -NQ ₉ CO-, -CONQ ₉ -, -NQ ₉ COO-, or -OCOO-, provided that any -CH ₂ - in -(CH ₂ ) _n - are not adjacent to each other. Q ₉ and Q ₁₀ each independently represent a hydrogen atom or a monovalent organic group. Q ₆ and Q ₇ each independently represent -H, -NHD, -N(D) ₂ , a group having -NHD, or a group having -N(D) _2. D represents a carbamate protecting group which is eliminated. However, at least one of Q ₅ , Q ₆ , and Q ₇ has a carbamate protecting group in the group. *1 represents a bond.) 14. The liquid crystal alignment film according to claim 13, wherein said Q ₅ is a group which can be replaced by -NQ ₉ -, -NQ ₉ CO-, or -CONQ ₉ -, provided that any -CH ₂ - in (CH ₂ ) _n - are not adjacent to each other. Further, a compound having at least one group selected from the group consisting of an oxiranyl group, an oxetanyl group, a protected isocyanate group, a protected isothiocyanate group, a group containing an oxazoline ring structure, a group containing a Meldrum's acid structure, a cyclocarbonate group, and a group represented by the following formula (d), or a compound represented by the following formula (e) (hereinafter, these are also collectively referred to as compound (C)). The liquid crystal alignment film according to any one of claims 13 to 14.

(R ₇₁ is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH ₂ -OH". R ₇₂ and R ₇₃ are each independently a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH ₂ -OH". * represents a bond. A represents an (m+n)-valent organic group having an aromatic ring. m represents an integer of 1 to 6, and n represents an integer of 0 to 4.) A method for producing a liquid crystal alignment film, comprising the following steps (1) to (3):
Step (1): A step of applying a liquid crystal aligning agent containing a polymer (A) which is a polyimide having a repeating unit represented by the following formula (3) and a repeating unit represented by the following formula (5) and has an imidization rate of 71% or more onto a substrate.
Step (2): A step of heating the coating film of the liquid crystal alignment agent obtained in step (1).
Step (3): A step of irradiating the film obtained in step (2) with polarized ultraviolet light.

(R ₃₁ to R ₃₄ in formula (3) are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group, and may be the same or different, but at least one of R ₃₁ to R ₃₄ represents a group other than a hydrogen atom as defined above. Y ₃ represents a divalent organic group represented by the following formula (I).)

(* represents a bond.)

(R ₅₁ to R ₅₄ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group, and may be the same or different, but at least one of R ₅₁ to R ₅₄ represents a group other than a hydrogen atom as defined above. Y ₅ each independently represents a divalent organic group having a partial structure represented by the following formula (J-1), or a divalent organic group represented by the following formula (J-2).)

(Q ₅ is a single bond, -(CH ₂ ) _n - (n is an integer of 1 to ₂₀ ), or a group which can be replaced by -O-, -COO-, -OCO-, -NQ _{9 -, -NQ 9 CO-, -CONQ 9 -, -NQ 9 CONQ 10 -, -NQ 9 COO-, or -OCOO-, provided that any -CH 2 - in - ( CH 2 )} n - are not adjacent to each other. _{Q 9 and} Q ₁₀ each independently represent a hydrogen atom or a monovalent organic group. Q ₆ and Q ₇ each independently represent -H, -NHD, -N(D) ₂ , a group having -NHD, or a group having -N(D) ₂ . _{Q 8} is -NHD, -N(D) ₂ , a group having -NHD, or -N(D) _2. D represents a carbamate protecting group. However, at least one of Q ₅ , Q ₆ and Q ₇ has a carbamate protecting group in the group. *1 represents a bond. 17. The method for producing a liquid crystal alignment film according to claim 16, wherein Q ₅ is a group which can be replaced by -NQ ₉ -, -NQ ₉ CO-, or -CONQ ₉ -, provided that any _{-CH 2} - in (CH ₂ ) n - are not adjacent to each other. The method for producing a liquid crystal alignment film according to claim 16 or 17, further comprising a compound having at least one group selected from the group consisting of an oxiranyl group, an oxetanyl group, a protected isocyanate group, a protected isothiocyanate group, a group containing an oxazoline ring structure, a group containing a Meldrum's acid structure, a cyclocarbonate group, and a group represented by the following formula (d), or a compound represented by the following formula (e) (hereinafter, these are also collectively referred to as compound (C)).

(R ₇₁ is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH ₂ -OH". R ₇₂ and R ₇₃ are each independently a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH ₂ -OH". * represents a bond. A represents an (m+n)-valent organic group having an aromatic ring. m represents an integer of 1 to 6, and n represents an integer of 0 to 4.) The method for producing a liquid crystal alignment film according to any one of claims 16 to 18, wherein the seal adhesion of the liquid crystal alignment film is greater than 4 N/ ^mm2 . The method for producing a liquid crystal alignment film according to any one of claims 16 to 19, further comprising the following step (4):
Step (4): A step of baking the film obtained in step (3) at a temperature of 100° C. or higher and at a temperature higher than that in step (2). The method for producing a liquid crystal alignment film according to any one of claims 16 to 20, wherein in step (2), the coating film of the liquid crystal alignment agent is heated at a temperature of 40 to 180°C. A method for producing a liquid crystal alignment film having a seal adhesion of greater than 4 N/ ^mm2 , comprising the following steps (1) to (3):
Step (1): A step of applying a liquid crystal aligning agent, which is characterized by containing a polymer (A) having a repeating unit represented by the following formula (3) and a repeating unit represented by the following formula (5), onto a substrate.
Step (2): A step of heating the coating film of the liquid crystal alignment agent obtained in step (1).
Step (3): A step of irradiating the film obtained in step (2) with polarized ultraviolet light.

(R ₃₁ to R ₃₄ in formula (3) are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group, and may be the same or different, but at least one of R ₃₁ to R ₃₄ represents a group other than a hydrogen atom as defined above. Y ₃ represents a divalent organic group represented by the following formula (I).)

(* represents a bond.)

(R ₅₁ to R ₅₄ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group, and may be the same or different, but at least one of R ₅₁ to R ₅₄ represents a group other than a hydrogen atom as defined above. Each Y ₅ independently represents a divalent organic group having a partial structure represented by the following formula (J-1).)

(Q ₅ is a single bond, -(CH ₂ ) _n - (n is an integer of 1 to 20), or a group which can be replaced with -O-, -COO-, -OCO-, -NQ ₉ CO-, -CONQ ₉ -, -NQ ₉ COO-, or -OCOO-, provided that any -CH ₂ - in -(CH ₂ ) _n - are not adjacent to each other. Q ₉ each independently represents a hydrogen atom or a monovalent organic group. Q ₆ and Q ₇ each independently represent -H, -NHD, -N(D) ₂ , a group having -NHD, or a group having -N(D) _2. D represents a carbamate protecting group, with the proviso that at least one of Q ₅ , Q ₆ , and Q ₇ has a carbamate protecting group in the group. *1 represents a bond.) 23. The method for producing a liquid crystal alignment film according to claim 22, wherein said Q ₅ is a group which can be replaced by -NQ ₉ CO- or -CONQ ₉ -, provided that any -CH ₂ - in (CH ₂ ) _n - are not adjacent to each other. The method for producing a liquid crystal alignment film according to claim 22 or 23, further comprising a compound having at least one group selected from the group consisting of an oxiranyl group, an oxetanyl group, a protected isocyanate group, a protected isothiocyanate group, a group containing an oxazoline ring structure, a group containing a Meldrum's acid structure, a cyclocarbonate group, and a group represented by the following formula (d), or a compound represented by the following formula (e) (hereinafter, these are also collectively referred to as compound (C)).

(R ₇₁ is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH ₂ -OH". R ₇₂ and R ₇₃ are each independently a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH ₂ -OH". * represents a bond. A represents an (m+n)-valent organic group having an aromatic ring. m represents an integer of 1 to 6, and n represents an integer of 0 to 4.) The method for producing a liquid crystal alignment film according to any one of claims 22 to 24, further comprising the following step (4):
Step (4): A step of baking the film obtained in step (3) at a temperature of 100° C. or higher and at a temperature higher than that in step (2). In the step (2), the coating film of the liquid crystal alignment agent is heated at a temperature of 40 to 180° C.;
The method for producing a liquid crystal alignment film according to any one of claims 22 to 25. A liquid crystal display element having a liquid crystal alignment film obtained by the method for producing a liquid crystal alignment film according to any one of claims 16 to 21. A liquid crystal display element having a liquid crystal alignment film obtained by the method for producing a liquid crystal alignment film according to any one of claims 22 to 26. A liquid crystal display element comprising a liquid crystal alignment film according to any one of claims 8 to 12. A liquid crystal display element comprising a liquid crystal alignment film according to any one of claims 13 to 15.