WO2020105561A1 - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display device - Google Patents

Abstract

Provided are: a liquid crystal alignment agent; a liquid crystal alignment film; and a liquid crystal display device, wherein the occurrence of afterimages caused by a long-term AC drive in an IPS- or FFS-mode liquid crystal display device can be suppressed. The liquid crystal alignment agent is characterized by containing a polyimide which is an imidized product of a polyimide precursor obtained by a polymerization reaction of a diamine component and a tetracarboxylic acid component containing a tetracarboxylic dianhydride represented by formula (1) or a derivative thereof, a tetracarboxylic dianhydride represented by formula (2) or a derivative thereof, and an aromatic tetracarboxylic dianhydride represented by formula (6). The liquid crystal alignment film is obtained from the liquid crystal alignment agent. The liquid crystal display device has the liquid crystal alignment film (X₁ is one among formulae (X1-1) to (X1-4), X₂ is (X2-1) or (X2-2), and X₃ is a tetravalent aromatic ring group).

Description

Liquid crystal aligning agent, liquid crystal aligning film, and liquid crystal display device

The present invention relates to a liquid crystal aligning agent, a liquid crystal aligning film obtained by the liquid crystal aligning agent, and a liquid crystal display device including the obtained liquid crystal aligning film.

A liquid crystal display element used for a liquid crystal television, a liquid crystal display, or the like is usually provided with a liquid crystal alignment film for controlling the alignment state of liquid crystals.
Currently, the most widely used liquid crystal alignment film in the industry is to coat the surface of a film made of polyamic acid and / or polyimide imidized on the electrode substrate with a cloth such as cotton, nylon or polyester. It is produced by rubbing in the direction, so-called rubbing treatment.
The rubbing treatment is an industrially useful method that is simple and excellent in productivity. However, due to the high performance, high definition, and large size of liquid crystal display elements, scratches on the surface of the alignment film generated by rubbing treatment, dust generation, the influence of mechanical force and static electricity, Various problems such as non-uniformity have become clear.

As an alternative method to the rubbing treatment, a photo-alignment method is known, which imparts liquid crystal alignment ability by irradiating polarized radiation. As the treatment by the photo-alignment method, a method utilizing a photo-isomerization reaction, a method utilizing a photo-crosslinking reaction, a method utilizing a photo-decomposition reaction, etc. have been proposed (see Non-Patent Document 1).

Patent Document 1 proposes to use a polyimide film having an alicyclic structure such as a cyclobutane ring in its main chain for a photo-alignment method.
The photo-alignment method as described above is a rubbing-less alignment treatment method, and can be produced by a simple manufacturing process industrially. In addition, in the liquid crystal display element of the IPS drive system or the FFS (fringe field switching) drive system, rubbing is performed. Since it can be expected to improve the contrast and viewing angle characteristics of a liquid crystal display device as compared with a liquid crystal alignment film obtained by a treatment method, it is attracting attention as a promising liquid crystal alignment treatment method.

The liquid crystal alignment film used for the liquid crystal display element of the IPS drive system or the FFS drive system is required to suppress afterimages due to long-term AC drive, in addition to basic properties such as excellent liquid crystal alignment and electrical properties.
However, the liquid crystal alignment film obtained by the photo-alignment method has a problem that the anisotropy with respect to the alignment direction of the polymer film is smaller than that obtained by rubbing. When the anisotropy is small, a sufficient liquid crystal orientation cannot be obtained, and when a liquid crystal display device is formed, problems such as an afterimage occur. On the other hand, in Patent Document 2, as a method of enhancing the anisotropy of the liquid crystal alignment film obtained by the photo-alignment method, a low molecular weight component generated by cutting the main chain of the polyimide by the light irradiation after the light irradiation is generated. Proposed to be removed.

Japanese Unexamined Patent Publication No. 9-297313 Japanese Patent Laid-Open No. 2011-107266

Conventionally, when performing a photo-alignment treatment of an organic coating such as a polyimide precursor and polyimide, according to the knowledge of the present inventor, the effect of photo-alignment is sensitive to the irradiation amount of light used, and the optimum irradiation of a relatively narrow range. It has been found that the amount is required, and if the irradiation amount out of the optimum range is deviated, the alignment may be incomplete in a part or the whole of the liquid crystal alignment film, and stable alignment of the liquid crystal may not be realized.
In particular, when a large-sized panel is processed by the photo-alignment method, it becomes difficult to perform the photo-alignment irradiation in which the light irradiation amount is uniformly controlled, and as a result, the stable alignment process by the photo-alignment method is performed. I found it difficult.

Therefore, an object of the present invention is to expand the range of the light irradiation amount (hereinafter, also referred to as an optimum irradiation amount margin) where good alignment control ability can be obtained, and to bring about a wide irradiation amount margin. Another object of the present invention is to provide a liquid crystal aligning agent capable of obtaining stable and stable liquid crystal aligning ability even in the case of a large panel. That is, an object of the present invention is to provide a liquid crystal aligning agent which has a wide range of light irradiation amount in which alignment control ability is stably generated and which can efficiently obtain a high quality liquid crystal aligning film.

As a result of intensive studies, the present inventors have found that the invention including a liquid crystal aligning agent having the following points can achieve the above object.
Tetracarboxylic dianhydride or its derivative represented by the following formula (1), tetracarboxylic dianhydride or its derivative represented by the following formula (2), and aromatic tetra represented by the following formula (6) A liquid crystal aligning agent comprising a polyimide which is an imidized product of a polyimide precursor obtained by a polymerization reaction of a tetracarboxylic acid component containing a carboxylic dianhydride and a diamine component.

However, X ₁ is a structure represented by any of the following formulas (X1-1) to (X1-4). X ₂ is a structure represented by the following formula (X2-1) or (X2-2). X ₃ is an aromatic ring having 4 bonds.

However, R ₃ to R ₆ each independently contain 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, or a fluorine atom. Are monovalent organic groups having 1 to 6 carbon atoms or phenyl groups, which may be the same or different, but at least one is other than a hydrogen atom. R ₇ to R ₂₃ 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, or a carbon atom containing a fluorine atom. It is a monovalent organic group of the numbers 1 to 6 or a phenyl group.

With the liquid crystal aligning agent of the present invention, it is possible to expand the light irradiation amount margin that brings about excellent photo-alignment treatment, which has been difficult in the past, and to obtain a liquid crystal aligning film having good afterimage characteristics. Therefore, the liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention has a high yield in liquid crystal panel production, and can reduce the afterimage caused by AC drive generated in the liquid crystal display device of the IPS drive system or the FFS drive system. A liquid crystal display device of an IPS drive system or an FFS drive system having excellent afterimage characteristics can be obtained.

The liquid crystal aligning agent of the present invention is, as described above, a polyimide which is an imidized product of a polyimide precursor obtained from a tetracarboxylic acid component derivative having a tetracarboxylic acid having a specific structure or a derivative thereof and a diamine component (hereinafter, a specific weight (Also referred to as coalescence).

<Specific polymer>
The specific polymer used in the present invention is a polyimide which is an imidized product of a polyimide precursor having a specific structure. The polyimide precursor is not particularly limited as long as it is a polyimide precursor that forms an imide ring by heating polyamic acid, polyamic acid ester, or the like, or by chemical imidization with a catalyst. From the viewpoint of easy progress of heating or chemical imidization, the polyimide precursor is more preferably a polyamic acid or a polyamic acid ester.
The imidization ratio of the polyimide is not particularly limited, but is preferably 10 to 100%, more preferably 50 to 100%, further preferably 50 to 80%.
Hereinafter, each component as a raw material forming the specific polymer will be described.

<Tetracarboxylic acid component>
The tetracarboxylic acid component used in the polymerization of the specific polymer of the present invention is not only a tetracarboxylic acid dianhydride, but also a derivative thereof, tetracarboxylic acid, tetracarboxylic acid dihalide, tetracarboxylic acid dialkyl ester or tetracarboxylic acid. A dialkyl ester dihalide can also be used.

The tetracarboxylic acid component used for the polymerization of the specific polymer of the present invention includes a tetracarboxylic acid dianhydride represented by the following formula (1) or a derivative thereof and a tetracarboxylic acid dianhydride represented by the following formula (2). It contains an anhydride or a derivative thereof and an aromatic tetracarboxylic dianhydride or a derivative thereof represented by the following formula (6). By containing the tetracarboxylic dianhydride of the above formula (1) or a derivative thereof, the light irradiation amount required for the photoreaction of the specific polymer is reduced, and a liquid crystal alignment film exhibiting high liquid crystal alignment is obtained. By containing the tetracarboxylic dianhydride or its derivative of the above formula (2) and the tetracarboxylic dianhydride or its derivative of the above formula (6), the photoreactivity of the specific polymer can be adjusted. As a result, a liquid crystal alignment film having a wide dose margin can be obtained.

X ₁ is a structure represented by any of the following formulas (X1-1) to (X1-4).

R ₃ to R ₆ each independently contain 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, or a fluorine atom. It is a monovalent organic group having 1 to 6 carbon atoms or a phenyl group, and at least one is other than a hydrogen atom. R ₇ to R ₂₃ each independently contain 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, or a fluorine atom. A monovalent organic group having 1 to 6 carbon atoms or a phenyl group.

In order to suppress an afterimage due to long-term AC driving, X ₁ is preferably at least one selected from the structures represented by any of the following formulas (X1-12) to (X1-16). X1-12) is particularly preferable.

The content ratio of the tetracarboxylic acid dianhydride represented by the above formula (1) or its derivative is preferably 50 to 98 mol%, more preferably 60 to 93 mol% with respect to the tetracarboxylic acid component to be reacted with the diamine component. It is preferably 65 to 87 mol%, and further preferably.

In the formula (2), X ₂ is the structure of the following formula (X2-1) or (X2-2).

Formula (X2-1) is preferable for X ₂ in order to suppress an afterimage due to long-term AC driving.

The content ratio of the tetracarboxylic acid dianhydride represented by the above formula (2) or its derivative is preferably 1 to 30 mol% and more preferably 5 to 25% with respect to 1 mol of all tetracarboxylic acid components. It is preferably 10 to 20%, and further preferably.

X ₃ is a tetravalent organic group, has an aromatic ring having four bonds, preferably at least one benzene ring or naphthalene ring, and has four bonds on the benzene ring or naphthalene ring. It is a ring. Specific examples include the structures of any of the following formulas (X3-1) to (X3-26). When enhancing the liquid crystal alignment, X3 is preferably any of (X3-1), (X3-5) to (X3-11), and (X3-14) to (X3-26). More preferably, a structure in which n in (X3-1), (X3-7), (X3-8) is 1 to 4, (X3-9) to (X3-10), or (X3-14) to (X3-26) is preferable.

The content ratio of the aromatic tetracarboxylic acid dianhydride represented by the above formula (6) or its derivative is preferably 1 to 20 mol% with respect to 1 mol of the tetracarboxylic acid component, and 2 to 15 mol% Is more preferable, and 3 to 15 mol% is even more preferable.

The tetracarboxylic acid component used in the polymerization of the specific polymer of the present invention is a tetracarboxylic acid dianhydride represented by the following formula (7) or the tetracarboxylic acid dianhydride represented by the following formula (7) in addition to the above formulas (1), (2) and (6). It may contain a derivative.

However, X ₄ is a tetravalent organic group other than X ₁ to X ₃ , but the structure thereof is not particularly limited. Specific examples include the following formulas (X4-1) to (X4-26) and tetravalent groups derived from ethylenediaminetetraacetic acid dianhydride. When enhancing the liquid crystal alignment, X4 includes (X4-8) to (X4-12), (X4-17) to (X4-19), and (X4-24) to (X4-26). ..

<Diamine>
The diamine component used for producing the specific polymer of the present invention is not particularly limited as long as it is a known diamine. From the viewpoint of suppressing the afterimage due to long-term AC driving, it is preferable to contain at least one diamine selected from the following formula (3), the following formula (4) and the following formula (5).

In the formulas (3) to (5), A ₁ and A ₄ are each independently a single bond, —CO—O—, —OCO—, —NRCO— (R is 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 ₁ -CO-NR _2- ( R ₁ and R ₂ each independently represent a hydrogen atom or a methyl group), a divalent chain hydrocarbon group having 2 to 20 carbon atoms, or —CH _{2 of the} divalent chain hydrocarbon group. -Is -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 ₁ -CO-NR _2- (R ₁ and R ₂ each independently represent a hydrogen atom or a methyl group), It represents a group (h1) substituted with a group selected from —NR— (R represents a methyl group), pyrrolidine, piperidine and piperazine. It should be noted that some or all of the hydrogen atoms contained in the chain hydrocarbon group of A ₁ and A ₄ and the group (h1) may be an alkyl group having 1 to 3 carbon atoms such as a methyl group, a fluorine atom, a chlorine atom, or the like. You may substitute with a halogen atom. A ₂ is a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a thiol group, a nitro group, a phosphoric acid group, or a monovalent organic group having 1 to 20 carbon atoms. A ₃ is a divalent chain hydrocarbon group having 1 to 20 carbon atoms, or —CH ₂ — of the divalent chain hydrocarbon group is —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 ₁ -CO-NR _2- (R ₁ and R ₂ each independently represent a hydrogen atom or a methyl group), -NR- (R represents a methyl group), pyrrolidine, piperidine, It represents a group (h2) substituted with a group selected from piperazine. In addition, a part or all of the hydrogen atoms contained in the chain hydrocarbon group of A ₃ and the group (h2) are substituted with an alkyl group having 1 to 3 carbon atoms such as a methyl group, a halogen atom such as a fluorine atom or a chlorine atom. You may. a is an integer of 1 to 4, and when a is 2 or more, the structures of A ₂ may be the same or different. b and c are integers of 1 or 2. d is an integer of 0 or 1. )

Examples of the divalent chain hydrocarbon group having 1 to 20 carbon atoms include methanediyl group, ethanediyl group, n-propanediyl group, i-propanediyl group, n-butanediyl group, i-butanediyl group, sec- Examples thereof include alkanediyl groups such as butanediyl group and t-butanediyl group; alkenediyl groups such as ethenediyl group, propenediyl group and butenediyl group; alkynediyl groups such as ethynediyl group, propyndiyl group and butynediyl group.

The monovalent organic group having 1 to 20 carbon atoms in A ₂ is, for example, a divalent chain hydrocarbon group having 1 to 20 carbon atoms in A ₃ , a group (h2), or a group having 1 to 20 carbon atoms. A part or all of the hydrogen atoms of the divalent chain hydrocarbon group and the group (h2) are substituted with an alkyl group having 1 to 3 carbon atoms such as a methyl group, or a halogen atom such as a fluorine atom or a chlorine atom. Examples of the group include a group obtained by adding one hydrogen atom to the group exemplified above.

In order to suppress an afterimage due to long-term AC driving, the following formulas (3) and (4) are represented by the following formulas (DA-3-1), (DA-4-1) to (DA-4-24), (DA-5-1) to (DA-5-3) are preferable. Among them, (DA-3-1), (DA-4-1) to (DA-4-11), (DA-4-13) to (DA-4-24), (DA-5-1) To (DA-5-2) are more preferable.

The content of the diamine represented by the above formula (3), formula (4) or formula (5) is preferably 50 to 100 mol%, and 70 mol% to 100 mol% with respect to 1 mol of the diamine component. Is more preferable.

From the viewpoint of improving the solubility of the polymer, the diamine used for producing the specific polymer of the present invention preferably contains a diamine represented by the following formula (8).

In the above formula (8), Y ₆ is a divalent organic group containing a structure represented by the following formula (9). A _6's each independently represent 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 ₆ is preferably a hydrogen atom or a methyl group.

D is a t-butoxycarbonyl group.

Specific examples of the divalent organic group having a structure represented by the above formula (9) include the following formula (J-1) or formula (J-2).

In the above formulas (J-1) and (J-1), * 1 represents a bond to NH-A ₆ , Q ₅ is a single bond,-(CH ₂ ) _n- (n is an integer of 1 to 20) Yes) or — (CH ₂ ) _n — and any —CH ₂ — are not adjacent to each other —O—, —COO—, —OCO—, —NR—, —NRCO—, —CONR—, — NRCONR-, -NRCOO-, and -OCOO- are substituted groups, and R represents a hydrogen atom or a monovalent organic group.
Q ₆ and Q ₇ each independently represent a group having —H, —NHD, —N (D) ₂ , —NHD, or a group having —N (D) ₂ . Q ₈ represents a group having —NHD, —N (D) ₂ , —NHD, or a group having —N (D) ₂ . D represents a t-butoxycarbonyl group. However, at least one of Q ₅ , Q ₆ and Q ₇ has a t-butoxycarbonyl group (Boc) in the group. More preferred are divalent organic groups represented by the following formulas (J-1-a) to (J-1-d) or (J-2-1).

The diamine used for the polymerization of the specific polymer of the present invention may contain a diamine represented by the following formula (10) in addition to the above formulas (3) to (5) and (8).

In the above formula (10), each A ₈ is 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 ₈ is preferably a hydrogen atom or a methyl group.
Y ₈ is a divalent organic group, and examples thereof include a group represented by any of the formulas (Y-1) to (Y-167) described in the pamphlet of WO2018 / 117239.

<Method for producing polyamic acid ester, polyamic acid and polyimide>
The polyimide precursor polyamic acid ester, polyamic acid and polyimide used in the present invention can be synthesized by a known method as described in, for example, International Publication WO 2013/157586.

<Liquid crystal aligning agent>
The liquid crystal aligning agent of the present invention has a form of a solution in which a polymer component such as a specific polymer is dissolved in an organic solvent. The weight average molecular weight of the specific polymer is preferably 2,000 to 500,000, more preferably 5,000 to 300,000, and further preferably 10,000 to 100,000. The number average molecular weight is preferably 1,000 to 250,000, more preferably 2,500 to 150,000, and further preferably 5,000 to 50,000.

The liquid crystal aligning agent of the present invention is a composition containing the above-mentioned specific polymer and an organic solvent, and may contain two or more specific polymers having different structures. Further, the liquid crystal aligning agent of the present invention may contain a polymer other than the specific polymer (hereinafter, also referred to as a second polymer) and various additives.

When the liquid crystal aligning agent of the present invention contains the second polymer, the ratio of the specific polymer to all the polymer components is preferably 5% by mass or more, and examples thereof include 5 to 95% by 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, and poly (meth). An acrylate etc. can be mentioned.
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 preferable as the second polymer.

Examples of the tetracarboxylic acid component for obtaining the second polyamic acid include a tetracarboxylic dianhydride represented by the following formula (11). Two or more kinds of the tetracarboxylic dianhydride may be used.

In the above formula (11), A is a tetravalent organic group, preferably a C4-30 tetravalent organic group.

The preferred structures of A are shown below, but the invention is not limited thereto.

Of the above structures, (A-1) and (A-2) are preferable from the viewpoint of further improving the photo-alignment property, and (A-4) is preferable from the viewpoint of further improving the relaxation rate of accumulated charges. (A-15) to (A-17) are preferable from the viewpoint of further improving the liquid crystal orientation and the relaxation rate of accumulated charges. The tetracarboxylic dianhydride component for obtaining the second polyamic acid may be one type of tetracarboxylic dianhydride, or may be a combination of two or more types of tetracarboxylic dianhydride. ..

The diamine component for obtaining the second polyamic acid can be appropriately determined according to the purpose, and for example, a diamine represented by the following formula (12) can be used.

(Y ₉ represents a divalent organic group. A _9's each independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkyl group having 2 to 5 carbon atoms. An alkynyl group. From the viewpoint of liquid crystal alignment, A ₉ is preferably a hydrogen atom or a methyl group.)

For the purpose of improving electric characteristics and relaxation characteristics, Y ₉ is preferably a divalent organic group having a tertiary nitrogen atom or a divalent organic group having —NH—CO—NH— in the molecule. Specific examples of formula (12) in the case where Y ₉ is a divalent organic group having a tertiary nitrogen atom include diamines having a pyrrole structure described in International Publication WO2017 / 126627, preferably the following formula (pr): The diamine represented by

In the formula (pr), R ¹ represents a hydrogen atom, hydrogen, a fluorine atom, a cyano group, a hydroxy group, or a methyl group. Each R ² independently represents a single bond or a group “* 1-R ³ —Ph- * 2”, and R ³ is a single bond, —O—, —COO—, —OCO—, — (CH ₂ ) _l Represents a divalent organic group selected from —, —O (CH ₂ ) _m O—, —CONH—, and —NHCO— (1 and m represent an integer of 1 to 5), and * 1 represents the formula (pr ) Represents a site to be bonded to the benzene ring, and * 2 represents a site to be bonded to the amino group in the formula (pr). Ph represents a phenylene group. n represents 1 to 3.
A diamine having a pyrrole structure described in International Publication WO2018 / 062197, preferably a diamine having a structure represented by the following formula (pn).

(R ¹ and R ² each independently represent a hydrogen atom or a methyl group, R ³ represents a single bond or a group “* 1-R ⁴ —Ph- * 2”, R ⁴ represents a single bond, —O—, _{-COO -, - OCO -, -} (CH 2) l -, - O (CH 2) m O -, - CONH-, and represents a divalent organic group selected from -NHCO- (l, m is 1 Represents an integer of 5 to 5), * 1 represents a site bonded to a benzene ring in formula (pn), * 2 represents a site bonded to an amino group in formula (pn), and Ph represents a phenylene group. .N represents 1 to 3),
A diamine having a carbazole structure described in International Publication WO2018 / 110354, preferably a diamine having a structure represented by the following formula (cz).

(R ¹ represents a hydrogen atom or a methyl group, and R ² represents a methyl group),
The diamine having a nitrogen-containing heterocycle described in paragraphs [0173] to [0188] of WO2015 / 046374, the diamine having a nitrogen-containing structure described in paragraph [0050] of JP-A-2016-218149, and the following formulas: A diamine represented by (BP).

(X is a biphenyl ring or a fluorene ring, Y is a benzene ring, a biphenyl ring, or a group selected from -phenyl-Z-phenyl-, and Z is -O-, -NH-, -CH ₂ -,-. A divalent group represented by SO ₂ —, —C (CH ₃ ) ₂ — or C (CF ₃ ) ₂ —, where 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, 2,4-diamino-6-methyl-s-triazine, 2,4-diamino-1,3,5-triazine, 4,6-diamino-2 -Vinyl-s-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) phenylamine, 4,4'-diphenylmethylamine, 4,4'-diphenylamine, 3,6-diaminocarbazole, 9-methyl-3,6 Examples include -diaminocarbazole, 9-ethyl-3,6-diaminocarbazole, and diamines represented by the following formulas (w1) to (w2).

(Sp is phenylene, pyrrolidine, piperidine, piperazine, a divalent chain hydrocarbon group having 2 to 20 carbon atoms, or —CH ₂ — of the divalent chain hydrocarbon group is —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) Represents a group), —COS—, —NR— (R represents a methyl group), pyrrolidine, piperidine, and a group substituted with a group selected from piperazine.)

When Y ₉ is a divalent organic group having —NH—CO—NH— in the molecule, specific examples of the above formula (12) include the above formula (4), in which A ₁ is —NH—CO— NH-, a group in which at least one of -CH _2- of a chain hydrocarbon group having 2 to 20 carbon atoms is replaced with -NH-CO-NH-, or a chain hydrocarbon group having 2 to 20 carbon atoms At least one of —CH ₂ — of the group is substituted with —NH—CO—NH—, and at least one of the other —CH ₂ — is —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-,-. Examples thereof include diamine in the case of a group substituted with a group selected from NR- (R represents a methyl group). Specific examples of more preferable diamines include diamines represented by the following formulas (U-1) to (U-9).

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

For the purpose of improving printability, a diamine compound having a carboxyl group (COOH group) or a hydroxyl group (OH group) can be used. Specifically, 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol, 2,4-diaminobenzoic acid, Mention may be made of 2,5-diaminobenzoic acid or 3,5-diaminobenzoic acid. Of these, 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid and 3,5-diaminobenzoic acid are preferable. Further, diamine compounds represented by the following formulas [3b-1] to [3b-4] and diamine compounds in which these amino groups are secondary amino groups can also be used.

(In the formula [3b-1], Q ¹ is 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 represent an integer of 1 to 4, and are represented by the formula [ 3b-2], m ³ and m ⁴ each independently represent an integer of 1 to 5, and in the formula [3b-3], Q ² represents a linear or branched alkylene group having 1 to 5 carbon atoms. , M ⁵ represents an integer of 1 to 5, and in the formula [3b-4], Q ³ and Q ⁴ are each independently 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- indicates, ^{m 6} is an integer of 1-4).

As the diamine component for obtaining the second polyamic acid, the diamine used in the specific polymer or a known diamine can be used in addition to the above, but the present invention is not limited thereto. The diamine component for obtaining the second polyamic acid may be one type of diamine, or may be a combination of two or more types of diamine.

The molecular weight of the second polymer contained in the liquid crystal aligning agent of the present invention is not particularly limited as long as a uniform and defect-free coating film can be formed on the substrate, and its preferable weight average molecular weight and number average molecular weight are specified. It is the same as in the case of the polymer.

As various additives to be added to the liquid crystal alignment agent, a dielectric or conductive substance for the purpose of changing the electrical properties such as the dielectric constant and conductivity of the liquid crystal alignment film, and improving the adhesion between the liquid crystal alignment film and the substrate. A silane coupling agent for the purpose of, a cross-linkable compound for the purpose of increasing the hardness and density of the film when formed into a liquid crystal alignment film, and further for the purpose of efficiently promoting imidization of the polyamic acid during baking of the coating film. Examples thereof include imidization accelerators.

Examples of the crosslinkable compound include an epoxy group, an isocyanate group, an oxetane group, a cyclocarbonate group, a blocked isocyanate group, a crosslinkable compound having a substituent such as a hydroxyl group or an alkoxyl group, and a crosslinkable compound having a polymerizable unsaturated group. It is preferable to add at least one compound selected from the group consisting of:
In addition, it is preferable that two or more of these substituents and polymerizable unsaturated bonds are contained in the crosslinkable compound from the viewpoint of enhancing crosslinkability. Specific examples of the crosslinkable compound include compounds having an epoxy group or an isocyanate group described in paragraphs [0169] to [0190] of WO 2011/132775, a compound having an oxetane group, a hydroxyl group, an alkoxyl group or a lower group. Amino resin having alkoxyalkyl group, benzene or phenolic compound having hydroxyl group or alkoxyl group, compound having cyclocarbonate group described in paragraphs [0103] to [0112] of International Publication WO 2012/014898, International Publication WO Examples thereof include compounds having a hydroxyalkylamide group described in 2015/072554 and compounds having a blocked isocyanate group described in WO 2015/141598.

More preferable specific examples of the crosslinkable compound include those represented by the following formulas (CL-1) to (CL-13), Takenate B-830, and B-882 (all of which are manufactured by Mitsui Chemicals, Inc.). ..

The content of the crosslinkable compound is preferably 0.1 to 100 parts by mass with respect to 100 parts by mass of all the polymer components contained in the liquid crystal aligning agent, and from the viewpoint of enhancing the alignment of the liquid crystal, it is more preferable. The amount is preferably 0.1 to 50 parts by mass, more preferably 1 to 50 parts by mass.

As the silane coupling agent, 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-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl -1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diaza Nonyl 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, p -Styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxy Examples include silane, tris- (trimethoxysilylpropyl) isocyanurate, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-isocyanatepropyltriethoxysilane. Be done. When using these silane coupling agents, from the viewpoint of ensuring the liquid crystal aligning property, the amount is preferably 0.1 to 30 parts by mass with respect to 100 parts by mass of all the polymer components contained in the liquid crystal aligning agent. , And more preferably 1 to 20 parts by mass.

The concentration of the polymer containing the specific polymer in the liquid crystal aligning agent of the present invention can be appropriately changed by setting the thickness of the coating film to be formed. Above all, it is preferably 1% by mass or more from the viewpoint of forming a uniform and defect-free coating film, and is preferably 10% by mass or less from the viewpoint of storage stability of the solution. A particularly preferable polymer concentration is 2 to 8% by mass.

The organic solvent contained in the liquid crystal aligning agent of the present invention is not particularly limited as long as the polymer component is uniformly dissolved therein. Specific examples thereof include N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, Examples thereof include 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethyl sulfoxide, dimethyl sulfone, γ-butyrolactone, 1,3-dimethyl-imidazolidinone and 3-methoxy-N, N-dimethylpropanamide. You may use these 1 type or in mixture of 2 or more types. Further, even if the solvent alone cannot dissolve the polymer component uniformly, it may be mixed with the above organic solvent as long as the polymer does not precipitate.

The liquid crystal aligning agent of the present invention may contain, in addition to the organic solvent for dissolving the polymer component, a solvent for improving coating film uniformity when the liquid crystal aligning agent is applied to the substrate. As the solvent, a solvent having a surface tension lower than that of the above organic solvent is generally used. Specific examples thereof include ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol. , 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, butyl cellosolve acetate, dipropylene glycol , 2- (2-ethoxypropoxy) propanol, lactate methyl ester, lactate ethyl ester, lactate n-propyl ester, lactate n-butyl ester, lactate isoamyl ester, diacetone alcohol, diisobutyl ketone, dipropylene glycol monomethyl ether, diisobutylcarbi And the like. Two or more of these solvents may be used in combination.

<Method for producing liquid crystal alignment film>
As described above, the method for producing a liquid crystal alignment film using the liquid crystal alignment agent of the present invention includes a step of applying the liquid crystal alignment agent (step (A)) and a step of baking the coating film obtained in the step (A) ( Step (B)), a step of irradiating the film obtained in step (B) with polarized ultraviolet light (step (C)), the film obtained in step (C) is 100 ° C. or higher, and It is characterized in that the step (step (D)) of firing at a temperature higher than that of B) is sequentially performed.

<Process (A)>
The substrate to which the liquid crystal aligning agent used in the present invention is applied is not particularly limited as long as it is a highly transparent substrate, and a glass substrate, a silicon nitride substrate, or a plastic substrate such as an acrylic substrate or a polycarbonate substrate may be used. it can. At that time, it is preferable to use a substrate on which an ITO electrode or the like for driving the liquid crystal is formed, from the viewpoint of simplifying the process. Further, in the reflection type liquid crystal display element, an opaque material such as a silicon wafer can be used if only one substrate is used, and in this case, a material that reflects light such as aluminum can be used for the electrode.
The method for applying the liquid crystal aligning agent is not particularly limited, but industrially, a method such as screen printing, offset printing, flexo printing, or inkjet method is generally used. Other coating methods include a dip method, a roll coater method, a slit coater method, a spinner method or a spray method, and these may be used depending on the purpose.

<Process (B)>
The step (B) is a step of baking the liquid crystal aligning agent applied on the substrate to form a film. After applying the liquid crystal aligning agent on the substrate, the solvent is evaporated or the amic acid or amic acid ester in the polymer is heated by a heating means such as a hot plate, a heat circulation type oven or an IR (infrared) type oven. Imidization can be performed. The drying and firing steps after applying the liquid crystal aligning agent of the present invention can be performed at any temperature and time and may be performed a plurality of times. The temperature for removing the organic solvent of the liquid crystal aligning agent can be, for example, in the range of 40 to 150 ° C. From the viewpoint of shortening the process, it may be carried out at 40 to 120 ° C. The firing time is not particularly limited, but examples thereof include 1 to 10 minutes or 1 to 5 minutes. When the thermal imidization of the amic acid or amic acid ester in the polymer is performed, a step of baking at a temperature range of 190 to 250 ° C. or 200 to 240 ° C. can be performed after the step of removing the organic solvent. .. The firing time is not particularly limited, but may be 5 to 40 minutes, or 5 to 30 minutes.

<Process (C)>
Step (C) is a step of irradiating the film obtained in step (B) with polarized ultraviolet light. As the ultraviolet rays, ultraviolet rays having a wavelength of 200 to 400 nm are preferably used, and among them, ultraviolet rays having a wavelength of 200 to 300 nm are more preferable. In order to improve the liquid crystal alignment, the substrate coated with the liquid crystal alignment film may be irradiated with ultraviolet rays while being heated at 50 to 250 ° C. The irradiation dose of the above radiation is preferably 1 to 10,000 mJ / cm ² . Among them, 100 to 5,000 mJ / cm ² is preferable. The liquid crystal alignment film thus produced can stably align liquid crystal molecules in a certain direction.
The higher the extinction ratio of polarized ultraviolet rays, the higher anisotropy can be imparted, which is preferable. Specifically, the extinction ratio of linearly polarized ultraviolet light is preferably 10: 1 or more, more preferably 20: 1 or more.

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

Furthermore, after performing either of the above steps (C) or (D), the obtained liquid crystal alignment film can be subjected to a contact treatment using water or a solvent.
The solvent used in the above contact treatment is not particularly limited as long as it is a solvent that dissolves the decomposition product generated from the liquid crystal alignment film by irradiation with ultraviolet rays. 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, 3- Examples thereof include methyl methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate or cyclohexyl acetate. Among them, water, 2-propanol, 1-methoxy-2-propanol or ethyl lactate is preferable from the viewpoint of versatility and solvent safety. More preferred is water, 1-methoxy-2-propanol or ethyl lactate. The solvent may be one kind or a combination of two or more kinds.

As the above-mentioned contact treatment, that is, treatment of water or solvent on the liquid crystal alignment film irradiated with polarized ultraviolet rays, immersion treatment or spray treatment (also referred to as spray treatment) can be mentioned. The treatment time in these treatments is preferably 10 seconds to 1 hour from the viewpoint of efficiently dissolving the decomposition product generated from the liquid crystal alignment film by ultraviolet rays. Above all, it is preferable to perform the immersion treatment for 1 to 30 minutes. The solvent used in the contact treatment may be heated at room temperature or heated, but is preferably 10 to 80 ° C. Above all, 20 to 50 ° C. is preferable. In addition, from the viewpoint of solubility of the decomposed product, ultrasonic treatment may be performed as necessary.

After the contact treatment, it is preferable to perform rinsing (also referred to as rinsing) with a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone or methyl ethyl ketone and baking of the liquid crystal alignment film. At that time, either one of rinsing and baking may be performed, or both may be performed. The firing temperature is preferably 150 to 300 ° C. Of these, 180 to 250 ° C. is preferable. More preferably, it is 200 to 230 ° C. The firing time is preferably 10 seconds to 30 minutes. Of these, 1 to 10 minutes is preferable.

INDUSTRIAL APPLICABILITY The liquid crystal alignment film of the present invention is suitable as a liquid crystal alignment film of a lateral electric field type liquid crystal display device such as an IPS system or an FFS system, and particularly useful as a liquid crystal alignment film of an FFS system liquid crystal display device. The liquid crystal display device is obtained by obtaining a substrate with a liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention, producing a liquid crystal cell by a known method, and using the liquid crystal cell.
As an example of a method of manufacturing a liquid crystal cell, a liquid crystal display element having a passive matrix structure will be described as an example. 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 that constitutes image display may be used.

Specifically, a transparent glass substrate is prepared, a common electrode is provided on one substrate, and a segment electrode is provided on the other substrate. These electrodes can be, for example, ITO electrodes and are patterned so that a desired image can be displayed. Next, an insulating film is provided on each substrate so as to cover the common electrodes and the segment electrodes. The insulating film can 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, one substrate is overlaid with the other substrate so that their liquid crystal alignment film surfaces face each other, and the periphery is bonded with a sealant. It is preferable that a spacer is usually mixed in the sealant in order to control the substrate gap, and spacers for controlling the substrate gap are also scattered on the in-plane portion where the sealant is not provided. An opening that can be filled with liquid crystal from the outside is provided in part of the sealant. Next, a liquid crystal material is injected into the space surrounded by the two substrates and the sealing agent through the opening provided in the sealing agent, and then the opening is sealed with an adhesive. For the injection, a vacuum injection method may be used, or a method utilizing a capillary phenomenon in the atmosphere may be used. As the liquid crystal material, either a positive type liquid crystal material or a negative type liquid crystal material may be used. Next, a polarizing plate is installed. Specifically, a pair of polarizing plates are attached to the surfaces 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 the afterimage caused by the long-term AC driving that occurs in the liquid crystal display element of the IPS driving method or the FFS driving method, and the brightness generated by the residual low molecular weight compound is generated. It is possible to obtain a liquid crystal alignment film which is free from problems such as points and which can be manufactured by a smaller number of steps than conventional ones.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. The abbreviations of the compounds and the methods for measuring each property below are as follows.
(Diamine)

(Boc represents a tert-butoxycarbonyl group.)

(Tetracarboxylic acid dianhydride)
CA-X-1: a compound represented by the following formula (CA-X-1)

(Compound C)
c-1: compound represented by the following formula (c-1) (other additives)
LS-4668: 3-glycidoxypropyltriethoxysilane (compound represented by the following (s-1))

(Organic solvent)
NMP: N-methyl-2-pyrrolidone, GBL: γ-butyrolactone,
BCS: butyl cellosolve,

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

[Synthesis of polymer]
<Synthesis example 1>
In a four-necked flask equipped with a stirrer and equipped with a nitrogen inlet tube, 3.62 g (14.8 mmol) of DA-h-1 and 4.75 g (14.8 mmol) of DA-h-2 and DA-i-1 were used. Of 1.92 g (17.8 mmol) and DA-j-1 of 4.05 g (11.9 mmol) were weighed out, and NMP was added so that the solid content concentration was 12% by mass, while feeding nitrogen. Stir to dissolve. While stirring the obtained solution, 10.1 g (45.2 mmol) of CA-1-1, 2.12 g (8.5 mmol) of CA-2-1, and 0.83 g (2 of CA-3-1) were used. .8 mmol) was added, and NMP was further added so that the solid content concentration became 15 mass%. Then, the mixture was stirred at 40 ° C. for 24 hours to obtain a polyamic acid solution.

30.0 g of the obtained polyamic acid solution was placed in a 100 mL four-necked flask equipped with a stirrer and equipped with a nitrogen introduction tube, NMP was added so that the solid content concentration was 10% by mass, and the mixture was stirred for 30 minutes. 2.80 g of acetic anhydride and 1.50 g of pyridine were added to the obtained polyamic acid solution, and the mixture was heated at 55 ° C. for 3 hours to carry out chemical imidization. The obtained reaction liquid was poured into methanol in an amount 3.5 times the mass of the reaction liquid while stirring, and the deposited precipitate was collected by filtration, and subsequently washed with methanol three times. The resin powder thus obtained was dried at 60 ° C. for 12 hours to obtain a polyimide (PI-A-1) powder. The imidation ratio of this polyimide resin powder was 62%. NMP was added to the obtained polyimide (PI-A-1), and the mixture was stirred at 70 ° C. for 24 hours to obtain a polyimide (PI-A-1) solution having a solid content concentration of 12 mass%.

<Synthesis examples 2 to 5>
By using the diamine component, the tetracarboxylic acid component, and the organic solvent shown in Table 1 below in the same procedure as in Synthesis Example 1, polyimide (PI-A-2) shown in Table 1 below A solution of (PI-A-4), (R-PI-1) and polyamic acids (PAA-B-1) to (PAA-B-3) was obtained. For polyamic acids (PAA-B-1) to (PAA-B-3), LS-4668 was added so as to be 1% by mass based on the solid content of polyamic acid.

In Table 1, the values in parentheses represent the compounding ratio (mol part) of each compound to 100 mol parts of the total amount of the tetracarboxylic acid components used in the synthesis for the tetracarboxylic acid component, and for the diamine acid component, The compounding ratio (mol part) of each compound to 100 mol parts of the total amount of diamine components used in the synthesis is shown. Regarding the organic solvent, the compounding ratio (parts by mass) of each organic solvent to the total amount of 100 parts by mass of the organic solvent used in the synthesis is shown.

[Preparation of liquid crystal aligning agent]
<Example 1>
The polyimide (PI-A-1) solution obtained in Synthesis Example 1 was diluted with NMP and BCS, and stirred at room temperature. Then, the obtained solution is filtered through a filter having a pore size of 0.5 μm to give a solvent composition ratio (NMP: BCS = 80: 20 (mass ratio)) and a liquid crystal alignment in which the polymer solid content concentration is 6% by mass. Agent (1) was obtained (see Table 2 below). No abnormalities such as turbidity and precipitation were observed in this liquid crystal aligning agent, and it was confirmed that the liquid crystal aligning agent was a uniform solution.

<Examples 2 to 4, Comparative Example 1>
Liquid crystal aligning agents (2) to (4) and (R1) were obtained in the same manner as in Example 1 except that each polymer shown in Table 2 below was used.

<Examples 5 to 7, Comparative Example 2>
Using the solution of the polyimide (PI-A-2) obtained in Synthesis Example 2 and the solution of the polyamic acid (PAA-B-1) obtained in Synthesis Example 6, diluted with NMP, GBL, and BCS, Further, the compound (c-1) was added to 3 parts by mass with respect to 100 parts by mass of all the polymers, and the mixture was stirred at room temperature. Then, the obtained solution is filtered with a filter having a pore size of 0.5 μm to give a polymer component ratio of (PI-A-2) :( PAA-B-1) = 40: 60 (mass ratio in terms of solid content). ), A solvent composition ratio of NMP: GBL: BCS = 50: 30: 20 (mass ratio), and a liquid crystal aligning agent (1) having a polymer solid content concentration of 6 mass% were obtained (see Table 2 below). No abnormalities such as turbidity and precipitation were observed in this liquid crystal aligning agent, and it was confirmed that the liquid crystal aligning agent was a uniform solution.

In Table 2, the numerical values in parentheses are the blending ratio of each polymer component or compound (C) with respect to the polymer and the compound (C) with respect to 100 parts by mass in total of the polymer components used for the preparation of the liquid crystal aligning agent ( Mass part). Regarding the organic solvent, the compounding ratio (parts by mass) of each organic solvent to 100 parts by mass of the total amount of the organic solvent used for preparing the liquid crystal aligning agent is shown.

[Production of liquid crystal display device]
A liquid crystal cell having the configuration of the FFS mode liquid crystal display element is manufactured.
First, a substrate with electrodes was prepared. The substrate is a glass substrate having a size of 30 mm × 50 mm and a thickness of 0.7 mm. On the substrate, an ITO electrode having a solid pattern, which constitutes a counter electrode as a first layer, is formed. A SiN (silicon nitride) film formed by the CVD method is formed as a second layer on the counter electrode of the first layer. The film thickness of the second-layer SiN film is 500 nm and functions as an interlayer insulating film. A comb-teeth-shaped pixel electrode formed by patterning an ITO film as a third layer is arranged on the second-layer SiN film to form two pixels of a first pixel and a second pixel. ing. The size of each pixel is 10 mm in length and about 5 mm in width. At this time, the first-layer counter electrode and the third-layer pixel electrode are electrically insulated by the action of the second-layer SiN film.

The pixel electrode of the third layer has a comb-tooth shape formed by arranging a plurality of "dogleg" -shaped electrode elements whose central portion is bent at an internal angle of 160 °. The width of each electrode element in the lateral direction is 3 μm, and the distance between the electrode elements is 6 μm. The pixel electrode that forms each pixel is configured by arranging a plurality of curved "dogleg" -shaped electrode elements in the central portion, so the shape of each pixel is not rectangular, but is similar to that of the electrode element. It has a shape that resembles a bold "dogleg" bent at a part. Each pixel is divided into upper and lower parts with a central bent portion as a boundary, and has a first region on the upper side and a second region on the lower side of the bent portion.

Next, a liquid crystal aligning agent was applied to the above-mentioned substrate with electrodes and a glass substrate having a columnar spacer having a height of 4 μm and having an ITO film formed on the back surface by spin coating. After drying on a hot plate at 80 ° C for 2 minutes, this coating film surface was irradiated with linearly polarized ultraviolet light of wavelength 254 nm with an extinction ratio of 26: 1 through a polarizing plate, and then a hot air circulation oven at 230 ° C. And was baked for 30 minutes to obtain a substrate with a liquid crystal alignment film having a film thickness of 100 nm. The liquid crystal alignment film formed on the electrode-attached substrate is a liquid crystal alignment film formed on the second glass substrate by performing alignment processing so that the direction that equally divides the interior angle of the pixel bend portion and the liquid crystal alignment direction are orthogonal to each other. Was subjected to an alignment treatment so that the alignment direction of the liquid crystal on the first substrate and the alignment direction of the liquid crystal on the second substrate coincided with each other when the liquid crystal cell was manufactured. The obtained two substrates with a liquid crystal alignment film are set as one set, the sealant is printed on the substrate with the liquid crystal injection port left, and the other substrate is bonded so that the liquid crystal alignment film surfaces face each other. It was Then, the sealant was cured to prepare an empty cell having a cell gap of 4 μm. Liquid crystal MLC-3019 (manufactured by Merck & Co., Inc.) was injected into the empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an FFS type liquid crystal display element. Then, the obtained liquid crystal display element was heated at 120 ° C. for 1 hour and left at 23 ° C. overnight, and then used for evaluation. ‥

[Evaluation]
-Evaluation of irradiation dose margin The liquid crystal display device obtained above was applied with an AC voltage of ± 5 V at a frequency of 60 Hz for 120 hours under a constant temperature environment of 60 ° C. Then, the pixel electrode of the liquid crystal display element and the counter electrode were short-circuited and left at room temperature for one day.
With respect to the liquid crystal display element that has been subjected to the above-described processing, the deviation between the alignment direction of the liquid crystal in the first region and the alignment direction of the liquid crystal in the second region of the pixel when no voltage is applied was calculated as an angle.
Specifically, a liquid crystal display element is installed between two polarizing plates arranged so that their polarization axes are orthogonal to each other, a backlight is turned on, and the liquid crystal is adjusted so that the transmitted light intensity in the first region of the pixel is minimized. The cell arrangement angle was adjusted, and then the rotation angle (hereinafter referred to as Δ _ac ) required when the liquid crystal cell was rotated so that the transmitted light intensity in the second region of the pixel was _minimized was obtained.
Using the lowest light irradiation amount E _min (mJ / cm ² ) where this Δ _ac is less than 0.15 ° and the highest light irradiation amount E _max (mJ / cm ² ), the following three-stage index is used. An evaluation was made. The evaluation results are shown in Table 3 below.

Excellent: The difference between E _max and E _min is 300 mJ / cm ² or more.
Good: The difference between E _max and E _min is 200 mJ / cm ² or more and less than 300 mJ / cm ² .
Poor: The difference between E _max and E _min is less than 200 mJ / cm ² .

As described above, the liquid crystal alignment films obtained from the liquid crystal alignment agents (1) to (7) used in Examples 1 to 7 of the present invention were irradiated with light of 150 to 350 mJ / cm ² or 150 to 450 mJ / cm ² . When the amount of irradiation was increased, _Δac was less than 0.15 °, and good afterimage characteristics were exhibited. On the other hand, the liquid crystal aligning agents (R1) and (R2) used in Comparative Examples 1 and 2 have a good afterimage of Δ _ac of less than 0.15 ° when irradiated with a light irradiation amount of 150 to 250 mJ / cm ^2. Although the characteristics were exhibited, when the light irradiation amount of 350 mJ / cm ² was applied, Δ _ac became 0.15 ° or more, and good afterimage characteristics could not be obtained. From the above, it is understood that the liquid crystal aligning agent of the present invention makes it possible to expand the light irradiation amount margin and obtain a liquid crystal aligning film having good afterimage characteristics. Therefore, the liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention has a high yield in liquid crystal panel production, and can reduce the afterimage caused by AC drive generated in the liquid crystal display device of the IPS drive system or the FFS drive system. A liquid crystal display device of an IPS drive system or an FFS drive system having excellent afterimage characteristics can be obtained.

The liquid crystal aligning agent of the present invention is useful for forming a liquid crystal aligning film in a wide variety of liquid crystal display devices such as an IPS driving system and an FFS driving system.
In addition, the entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2018-216789 filed on Nov. 19, 2018 are cited herein as disclosure of the specification of the present invention. , Take in.

Claims (15)

1. Tetracarboxylic dianhydride or its derivative represented by the following formula (1), tetracarboxylic dianhydride or its derivative represented by the following formula (2), and aromatic tetra represented by the following formula (6) A liquid crystal aligning agent comprising a polyimide which is an imidized product of a polyimide precursor obtained by a polymerization reaction of a tetracarboxylic acid component containing a carboxylic dianhydride and a diamine component.
   

   

   (X ₁ is a structure represented by any of the following formulas (X1-1) to (X1-4). X ₂ is a structure represented by the following formula (X2-1) or (X2-2). Yes, X ₃ is an aromatic ring having 4 bonds.)
   

   

   (R ₃ to R ₆ each independently contain 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, or a fluorine atom. A monovalent organic group having 1 to 6 carbon atoms or a phenyl group, at least one of which is other than a hydrogen atom, and R ₇ to R ₂₃ each independently represent a hydrogen atom, a halogen atom, or a C 1 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.)
   

   
2. The liquid crystal aligning agent according to claim 1, wherein the imidization ratio of the polyimide is 10 to 100%.
3. The tetracarboxylic acid component according to claim 1 or 2, wherein the tetracarboxylic acid dianhydride represented by the formula (2) or a derivative thereof is contained in an amount of 1 to 30 mol% based on the tetracarboxylic acid component. Liquid crystal aligning agent.
4. 3. The tetracarboxylic acid component according to claim 1, wherein the tetracarboxylic acid dianhydride represented by the formula (6) or a derivative thereof is contained in an amount of 1 to 20 mol% based on the tetracarboxylic acid component. Liquid crystal aligning agent.
5. 5. The liquid crystal alignment according to claim 1, wherein in the formula (1), X ₁ is at least one selected from structures represented by any of the following formulas (X1-12) to (X1-16). Agent.
   

   
6. 5. The liquid crystal aligning agent according to claim 1, wherein X ₁ in the formula (1) is at least one selected from the structures represented by any of the formulas (X1-12) to (X1-16). ..
7. 7. The liquid crystal aligning agent according to claim 1, wherein in the formula (2), X ₂ has a structure represented by the formula (X2-1).
8. 8. The liquid crystal according to claim 1, wherein the diamine component contains at least one diamine selected from the structures represented by any of the following formulas (3), (4) and (5). Alignment agent.
   

   

   (A ₁ and A ₄ are each independently a single bond, —CO—O—, —OCO—, —NRCO— (R represents a hydrogen atom or a methyl group), —NRCOO— (R is a hydrogen atom. Or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), -COS-, -NR ₁ -CO-NR _2- (R ₁ and R ₂ are each independently hydrogen. Represents an atom or a methyl group), a divalent chain hydrocarbon group having 2 to 20 carbon atoms, or —CH ₂ — of the divalent chain hydrocarbon group is —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 ₁ —CO—NR ₂ — (R ₁ and R ₂ each independently represent a hydrogen atom or a methyl group), —NR— (R represents a methyl group). Represents a group (h1) substituted with a group selected from pyrrolidine, piperidine, and piperazine, A ₂ represents a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a thiol group, a nitro group, a phosphoric acid group, or a carbon number. 1 to 20 monovalent organic groups, wherein the chain hydrocarbon group of A ₁ and A ₄ and part or all of the hydrogen atoms of the group (h1) have an alkyl group of 1 to 3 carbon atoms, A ₃ may be substituted with a halogen atom, A ₃ is a divalent chain hydrocarbon group having 1 to 20 carbon atoms, or —CH ₂ — of the divalent chain hydrocarbon group is —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 ₁ —CO—NR ₂ — (R ₁ and R ₂ each independently represent a hydrogen atom or a methyl group), —NR— (R is a methyl group. Represents a group) and a group (h2) substituted with a group selected from pyrrolidine, piperidine and piperazine, wherein part or all of the hydrogen atoms contained in the chain hydrocarbon group of A ₃ and the group (h2). May be substituted with an alkyl group having 1 to 3 carbon atoms or a halogen atom, a is an integer of 1 to 4, and when a is 2 or more, A ₂ may be the same or different. , Each independently being an integer of 1 or 2. d is an integer of 0 or 1.)
9. The diamine component is selected from the group consisting of the following formulas (DA-3-1), (DA-4-1) to (DA-4-24), and (DA-5-1) to (DA-5-3). The liquid crystal aligning agent according to claim 1, which contains at least one diamine selected.
   

   

   

   

   
10. A method for producing a liquid crystal alignment film, which includes the following steps (A), (B), (C), and (D).
    Step (A): Step of applying the liquid crystal aligning agent according to any one of claims 1 to 9 Step (B): Step of firing the coating film obtained in Step (A) Step (C): Step (B) Step (D) of irradiating the film obtained in step with polarized ultraviolet rays: a step of firing the film obtained in step (C) at a temperature of 100 ° C. or higher and higher than that in step (B).
11. The method for producing a liquid crystal alignment film according to claim 10, wherein in the step (B), baking is performed at 50 ° C to 150 ° C.
12. The method for producing a liquid crystal alignment film according to claim 10 or 11, wherein in the step (D), the film is baked at 150 to 300 ° C.
13. A liquid crystal alignment film obtained by using the liquid crystal alignment agent according to any one of claims 1 to 9.
14. A liquid crystal display device comprising the liquid crystal alignment film according to claim 13.
15. The liquid crystal display device according to claim 14, wherein the liquid crystal is driven by a horizontal electric field.