WO2020100918A1 - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element using same - Google Patents

Abstract

Provided is a liquid crystal alignment agent, by which a liquid crystal alignment film having both good liquid crystal alignment properties and accumulated electric charge relaxation properties can be obtained. This liquid crystal alignment agent is characterized by containing at least one kind of polymer (P1) and an imidized polymer thereof, the polymer (P1) being selected from the group consisting of: a terminal-capped first polyimide precursor which is obtained by polymerizing a tetracarborboxylic acid component and a diamine component including at least one selected from the group consisting of diamines having partial skeletons represented by formulae (ND-1) to (ND-4), and a diamine represented by (ND-5, and then reacting the resultant with a terminal capping agent. (R¹, R²¹, and R²² each independently represent a hydrogen atom or a methyl group, R⁵¹ and R⁵² each independently represent a hydrogen atom or a methyl group, and S_p3 and S_p4 represent a divalent organic group. A₅ represents a single bond or a divalent organic group.)

Description

Liquid crystal aligning agent, liquid crystal aligning film, and liquid crystal display device using the same

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

Currently, polyimide films are often used for liquid crystal alignment films used in liquid crystal display devices. The liquid crystal alignment film of this polyimide film is prepared by a method of applying a solution of a polyimide precursor polyamic acid or a solvent-soluble polyimide solution to a substrate and subjecting the film obtained by baking to an alignment treatment such as a rubbing treatment. Has been done. This polyamic acid or solvent-soluble polyimide is generally produced by a polycondensation reaction between a tetracarboxylic acid derivative such as tetracarboxylic dianhydride and a diamine compound.

It has been proposed to seal the ends of the polyamic acid or the polyimide in order to improve the liquid crystal alignment property of the liquid crystal alignment film obtained from the polyamic acid or the polyimide or the property of erasing the afterimage that occurs when a voltage is applied.

For example, in Patent Document 1, in order to shorten the afterimage erasing time in a liquid crystal display element, the end-capping polymer (1) selected from end-capped polyamic acid and the like, and end-unsealed polyamic acid and the like are selected. A liquid crystal aligning agent containing an uncapped polymer (2), wherein the ratio of the terminal sealing polymer (1) to the total amount of the polymer in the liquid crystal aligning agent is 5 to 60% by weight. It is described that a liquid crystal aligning agent characterized by
Further, Patent Document 2 describes that a varnish for a photo-alignment film containing a first polyamic acid compound having a terminal skeleton containing no primary amino group is used in order to prevent DC afterimage in a liquid crystal display device. Has been done.

Japanese Patent No. 4336922 Japanese Patent Laid-Open No. 2017-90781

In recent years, liquid crystal display elements have been improved in performance and area, and power consumption of display devices has been improved. In addition, liquid crystal display elements have come to be used in various environments, and characteristics required for liquid crystal alignment films. Is getting tougher. In particular, as the use of liquid crystal display devices progresses, the problem that electric charges are accumulated in the liquid crystal alignment film and the problem that it becomes difficult to secure a good liquid crystal alignment property become remarkable.

If the charge is accumulated in the liquid crystal alignment film, an afterimage is likely to occur even when driven for a short time. In addition, if good liquid crystal alignment cannot be ensured, light leakage and alignment defects are likely to occur. For this reason, although there is a strong demand for good stored charge relaxation characteristics and liquid crystal orientation, there have been cases where the conventionally proposed technology cannot sufficiently satisfy both of these requirements.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid crystal aligning agent that can obtain a liquid crystal aligning film having both good liquid crystal aligning property and accumulated charge relaxation property.

As a result of intensive studies, the present inventors have used a specific diamine, and a liquid crystal aligning agent containing a specific polyimide-based polymer having a terminal blocked, that the above-mentioned problems can be achieved. I found it.
The present invention is based on such findings and is an invention including a liquid crystal aligning agent having the following gist.
At least one diamine selected from the group consisting of a diamine containing a partial skeleton represented by any of the following formulas (ND-1) to (ND-4) and a diamine represented by (ND-5): A diamine component containing and a tetracarboxylic acid component are polymerized, and obtained by reacting with an end-capping agent, and the end-capped first polyimide precursor and a group consisting of its imidized polymer A liquid crystal aligning agent comprising at least one polymer (P1) selected.

(R ¹ , R ²¹ , and R ²² each independently represent a hydrogen atom or a methyl group, and R ⁵¹ and R ⁵² each independently represent a hydrogen atom or a methyl group. S _p3 and S _p4 are , Each independently represents a divalent organic group. A ₅ represents a single bond or a divalent organic group.)

According to the liquid crystal aligning agent of the present invention, it is possible to obtain a liquid crystal aligning film having both good liquid crystal aligning property and accumulated charge relaxation property.

<Polymer (P1)>
The liquid crystal aligning agent of the present invention is selected from the group consisting of a diamine having a partial skeleton represented by any of the above formulas (ND-1) to (ND-4) and a diamine represented by (ND-5). A diamine component containing at least one diamine and a tetracarboxylic acid component, which are polymerized and reacted with an end-capping agent, to obtain a terminal-capped first polyimide precursor and imidization thereof. It contains at least one polymer (P1) selected from the group consisting of polymers.

Hereinafter, each component as a raw material of the polymer (P1) will be described.
(Specific diamine)
The specific diamine is at least one selected from the group consisting of a diamine having a partial skeleton represented by the following formulas (ND-1) to (ND-4) and a diamine represented by any one of (ND-5). It is a diamine.

In the above formula, R ¹ , R ²¹ and R ²² each independently represent a hydrogen atom or a methyl group. R ⁵¹ and R ⁵² each independently represent a hydrogen atom or a methyl group. S _p3 and S _p4 represent a divalent organic group. A ₅ represents a single bond or a divalent organic group.

Preferred examples of the divalent organic group of S _p3 and S _p4 include, for example, phenylene, pyrrolidine, piperidine, piperazine, a divalent chain hydrocarbon group having 2 to 20 carbon atoms, or the divalent chain form. The hydrocarbon group —CH ₂ — is —O—, —CO—, —CO—O—, —O—CO—, —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. The group substituted by the selected group is mentioned.

Examples of the divalent chain hydrocarbon group in S _p3 and S _p4 include ethylene group, propanediyl group, butanediyl group, pentanediyl group, hexanezyl group, heptanediyl group, octanediyl group, nonanediyl group and decandiyl group. Can be mentioned.

Preferred examples of the above divalent organic group for A ₅ include 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—, —O—CO—, —NRCO— (R represents a hydrogen atom or a methyl group), —NRCOO— (R represents a hydrogen atom or a methyl group), — Examples thereof include a group substituted with CONR- (R represents a hydrogen atom or a methyl group).
Specific examples of the divalent chain hydrocarbon group for A ₅ include methylene groups and the divalent chain hydrocarbon groups exemplified for Sp ₃ and Sp ₄ .

Preferred examples of the diamine having a partial skeleton represented by the formula (ND-1) include the following formulas (ND-1-1) and (ND-1-2).

In the above formula, R ¹ and R ² represent a hydrogen atom or a methyl group. R ¹¹ and R ²² each independently represent a single bond or * 1-R ³ -Ph- * 2. R ³ is a single bond, a divalent group selected from —O—, —COO—, —OCO—, — (CH ₂ ) _l —, —O (CH ₂ ) _m O—, —CONH—, and —NHCO—. Represents an organic group (l and m represent an integer of 1 to 5). In addition, * 1 represents a site that bonds to the benzene ring in the formula (ND-1-1) or (ND-1-2), and * 2 represents the formula (ND-1-1) or (ND-1-2). ) Represents a site to be bonded to the amino group. Ph represents a phenylene group. n represents 1 to 3.
In the above formulas (ND-1-1) and (ND-1-2), the substitution positions of the pyrrole ring are preferably the 2-position and the 5-position from the viewpoint of easy synthesis.

Specific examples of the diamines represented by the above formulas (ND-1-1) and (ND-1-2) include diamines represented by the following formulas (n1-1) to (n1-14). Can be mentioned.

Examples of the diamine having a partial skeleton represented by the formula (ND-2) include diamines represented by the following formulas (ND-2-1) to (ND-2-3).

In the above ^formula, R ^{21, R 22} are each the same meaning, including the preferred embodiment and ^{R 21, R 22} in the formula (ND-2). R ²⁴ represents a single bond or the structure of the following formula (Ar), and n represents an integer of 1 to 3. * Represents a bond. Further, any hydrogen atom of the benzene ring is a monovalent organic group such as an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom) or the like. It may be substituted with a group.

In the above formula (Ar), R ⁵ is a single bond, —O—, —COO—, —OCO—, — (CH ₂ ) _l —, —O (CH ₂ ) _m O—, —CONR—, and — It represents a divalent organic group selected from NRCO-, and k is an integer of 1 to 5. R represents hydrogen or a monovalent organic group, and l and m each represent an integer of 1 to 5. * 1 and * 2 represent a bond, and * ₁ bonds to the benzene ring in formulas (ND-2-1) to (ND-2-3).
Examples of the monovalent organic group for R in the above formula (Ar) include alkyl groups having 1 to 3 carbon atoms.

Specific preferred examples of the diamines represented by the above formulas (ND-2-1) to (ND-2-3) include diamines represented by the following formulas (n2-1) to (n2-6). ..

Specific examples of the diamine having a partial skeleton represented by the above formula (ND-3) or (ND-4) include diamines represented by the following formulas (ND-3-1) or (ND-4-1). Is mentioned.

Specific preferred examples of the diamine represented by the above formula (ND-3-1) include diamines represented by the following formulas (n3-1) to (n3-7).

Preferred specific examples of the diamine represented by the above formula (ND-4-1) include diamines represented by the following formulas (n4-1) to (n4-6).

Specific preferred examples of the diamine represented by the above formula (ND-5) include diamines represented by the following formulas (n5-1) to (n5-8).

The content of the specific diamine is preferably 5 mol% or more, more preferably 10 mol% or more, further preferably 20 mol% or more, and more preferably 50 mol% or more of the entire diamine component. Particularly preferred.
The specific diamine is selected from one type depending on the solubility of the polymer (P1) in the solvent, the coating property of the liquid crystal alignment agent, the alignment property of the liquid crystal when used as a liquid crystal alignment film, the voltage holding ratio, the accumulated charge, and the like. Or, two or more kinds can be used.

As the diamine component for obtaining the polymer (P1), a diamine other than the specific diamine (hereinafter, also referred to as other diamine) may be contained. Other diamines include diamines represented by the following general formula (2).

In the above formula (2), A ₁ and A ₂ 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. Is. From the viewpoint of liquid crystal alignment, A ₁ and A ₂ are preferably hydrogen atoms or methyl groups. Examples of the structure of Y ₁ are as shown in the following formulas (Y-1) to (Y-68).

(Boc in the above formula represents a tert-butoxycarbonyl group. * Represents a bond.)

Further, as the other diamine, a diamine having a thiophene or furan structure described in International Publication WO2018 / 092759, preferably a diamine represented by the following formula (sf); 2,3-diaminopyridine, 2,6-diamino Pyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, diaminoorganosiloxane such as 1,3-bis (3-aminopropyl) -tetramethyldisiloxane, aliphatic diamine such as metaxylenediamine, 4,4 Examples thereof include alicyclic diamine such as methylenebis (cyclohexylamine). Other diamines may be used alone or in combination of two or more.

In the above formula (sf), Y ₁ represents a sulfur atom or an oxygen atom, R ₂ independently represents a single bond or * 1-R ⁵ —Ph- * 2, and R ⁵ represents a single bond, Represents a divalent organic group selected from —O—, —COO—, —OCO—, — (CH ₂ ) _l —, —O (CH ₂ ) _m O—, —CONH—, and —NHCO— (l , M is an integer of 1 to 5). In addition, * 1 represents the part couple | bonded with the benzene ring in a formula (sf), and * 2 represents the part couple | bonded with the amino group in a formula (sf). Ph represents a phenylene group. n is 1 to 3. )

(Tetracarboxylic acid component)
As the tetracarboxylic acid component for obtaining the polymer (P1), a tetracarboxylic dianhydride represented by the following formula (1) or a derivative thereof (tetracarboxylic acid, tetracarboxylic acid dihalide, tetracarboxylic acid dialkyl ester) Or a tetracarboxylic acid dialkyl ester dihalide) (these are collectively referred to as a first tetracarboxylic acid component).

In the above formula, X represents a tetravalent organic group. Examples thereof include at least one selected from the group consisting of the following formulas (X-1) to (X-14).

(X and y are each independently a single bond, methylene, ethylene, propylene, ether (—O—), carbonyl (—CO—), ester (—COO—), phenylene, sulfonyl (—SO ₂ —) or Represents an amide group (—CONH—), Z ¹ to Z ⁴ each independently represent a hydrogen atom, a methyl group, an ethyl group, a propyl group, a chlorine atom or a phenyl group, and j and k each independently. , 0 or 1, m is an integer of 0 to 5. * represents a bond.)

Preferred examples of the above formula (X-1) include structures represented by the following formulas (X1-1) to (X1-4).

Preferred examples of the formula (X-13) include the following formulas (X13-1) to (X13-4).

The content of the first tetracarboxylic acid component is preferably 5 mol% or more, more preferably 10 mol% or more, further preferably 20 mol% or more, based on the total amount of the tetracarboxylic acid component, 50 It is particularly preferably at least mol%.

The first tetracarboxylic acid component has properties such as solubility of the polymer (P1) in a solvent, applicability of a liquid crystal aligning agent, liquid crystal orientation when used as a liquid crystal orientation film, voltage holding ratio, and accumulated charge. Depending on the type, one type or two or more types can be used.

As the tetracarboxylic acid component for obtaining the polymer (P1) of the present invention, other tetracarboxylic acid components other than the first tetracarboxylic acid component can be used. Examples of the other tetracarboxylic acid component include the following tetracarboxylic acid dianhydride, tetracarboxylic acid dihalide, tetracarboxylic acid dialkyl ester or tetracarboxylic acid dialkyl ester dihalide derived from the tetracarboxylic acid dianhydride.
Specifically, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-anthracenetetracarboxylic dianhydride Anhydride, 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride, bis (3,4-dicarboxyphenyl) dimethylsilane dianhydride, bis (3,4-dicarboxyphenyl) diphenylsilane dianhydride , 2,6-bis (3,4-dicarboxyphenyl) pyridine dianhydride and the like.
Other tetracarboxylic acid components may be used alone or in combination of two or more.

(End capping agent)
In the present invention, the terminal blocking agent is a compound capable of reacting with the unreacted acid terminal and / or amine terminal of the polyimide precursor or its imidized polymer to block these.
The terminal blocking agent is not particularly limited as long as it is a compound capable of blocking an acid terminal and / or an amine terminal, but a monoamine or an acid anhydride is preferable. The monoamine can cap the acid end of the polyimide precursor or its imidized polymer, and the acid anhydride can cap the amine end of the polyimide precursor or its imidized polymer.

Preferred examples of monoamines include aniline, 2-aminophenol, 3-aminophenol, 2-amino-m-cresol, 2-amino-p-cresol, 3-amino-o-cresol, 4-amino-o-cresol, 4-amino-m-cresol, 5-amino-o-cresol, 6-amino-m-cresol, 4-amino-2,3-xylenol, 4-amino-3,5-xylenol, 6-amino-2, 4-xylenol, 2-amino-4-ethylphenol, 3-amino-4-ethylphenol, 2-amino-4-tert-butylphenol, 2-amino-4-phenylphenol, 4-amino-2,6-diphenyl Phenol, 4-aminosalicylic acid, 5-aminosalicylic acid, 6-aminosalicylic acid, 2-aminobenzoic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, 2-amino-m-toluene acid, 3-amino-o- Toluene acid, 3-amino-p-toluene acid, 4-amino-m-toluene acid, 6-amino-o-toluene acid, 6-amino-m-toluene acid, 3-aminobenzenesulfonic acid, 4-aminobenzene Examples thereof include sulfonic acid and 4-aminotoluene-3-sulfonic acid. You may use 2 or more types of these.

The acid anhydride is preferably an acid anhydride having a cyclic structure or an acid anhydride having a crosslinkable group. Examples of the acid anhydride include phthalic anhydride, maleic anhydride, nadic acid anhydride, cyclohexanedicarboxylic acid anhydride, 3-hydroxyphthalic acid anhydride, trimetic acid anhydride, and the following formulas (m-1) to (m-6). ) And the like. You may use 2 or more types of these.

<Polymer (P2)>
The liquid crystal aligning agent of the present invention is at least 1 selected from the group consisting of a second polyimide precursor and an imidized polymer thereof obtained by reacting a diamine component and a tetracarboxylic acid component together with the polymer (P1). It may further contain a seed polymer (P2). In this case, for example, the polymer (P1) has a function of excellent stored charge relaxation property, and the polymer (P2) has a function of excellent liquid crystal alignment, which is preferable.
The polyimide precursor of the polymer (P2) or its imidized polymer may have the terminal blocked, and in that case, the diamine component of the polymer (P2) contains a diamine other than the specific diamine. Specific examples include, in addition to the other diamines exemplified as the polymer (P1), diamines described in International Publication WO2018-159733 and International Publication WO2016-104365 for vertically aligning liquid crystals. In order to enhance the response speed of the oriented diamine such as the specific diamine (1) described above and the liquid crystal, polymerization initiation described in the specific diamine (4) described in International Publication WO2016-104365 and Japanese Unexamined Patent Publication No. 2018-081225 You may use diamine etc. which have a function.

When the end of the polymer (P2) is not blocked, as the diamine component for obtaining the polymer (P2), a diamine component for obtaining the polymer (P1) may be used in addition to the diamine exemplified above. it can.
The diamine component for obtaining the polymer (P2) may contain at least one diamine selected from the following formulas (3), (4) and (5) from the viewpoint of enhancing the liquid crystal alignment. ..

In the above formula, A ₁ and A ₄ each independently represent a single bond or a divalent organic group, and A ₂ is a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a thiol group, a nitro group or a phosphoric acid. Represents a group or a monovalent organic group having 1 to 20 carbon atoms, and A ₃ represents a divalent organic group. 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 each independently an integer of 1 or 2. d is an integer of 0 or 1.

The divalent organic group for A ₁ and A ₄ is 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 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 Represents a methyl group), pyrrolidine, piperidine, and a group (h1) substituted with a group selected from piperazine. Even if a part or all of the hydrogen atoms contained in the chain hydrocarbon group and the group (h1) are replaced 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. Good.

The divalent organic group in A ₃ above is a divalent chain hydrocarbon group having 1 to 20 carbon atoms, or —CH ₂ — of the divalent chain hydrocarbon group is —O— or —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) 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), pyrrolidine, piperidine, and piperazine, and a group (h2) substituted with a selected group. 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.

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-butanediyl group. Group, alkanediyl group such as t-butanediyl group;
Examples thereof include alkenediyl groups such as ethenediyl group, propenediyl group and butenediyl group; and alkynediyl groups such as ethenediyl group, propynediyl 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. 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.

Preferred specific examples of at least one diamine selected from the above formula (3), the following formula (4) and the following formula (5) include the following formulas (DA-3-1), (DA-4-1) to (DA-4-1). At least one diamine selected from the group consisting of DA-4-23) and (DA-5-1) to (DA-5-3) can be given.

From the viewpoint of enhancing the liquid crystal alignment, the total amount of at least one diamine selected from the above formulas (3), (4) and (5) is 10 based on the total amount of the diamine components for obtaining the polymer (P2). It is preferably at least mol%.

From the viewpoint of enhancing the functional separation of the polymer (P1) and the polymer (P2), the diamine component for obtaining the polymer (P1) and / or the polymer (P2) is a diamine represented by the following formula (6). It is preferable to include.

In the above formula, Y ₆ represents a divalent organic group containing a structure represented by the following formula (7). 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.)

Examples of the divalent organic group containing the structure represented by the above formula (7) include groups represented by the following formula (J-1) or formula (J-2).

In the above formula, R ₅ is a single bond, — (CH ₂ ) _n — (n is an integer of 1 to 20), or — (CH ₂ ) _n — and any —CH ₂ — are not adjacent to each other. Represents a group replaced with -O-, -COO-, -OCO-, -NR-, -NRCO-, -CONR-, -NRCONR-, -NRCOO-, -OCOO-. R represents a hydrogen atom or a monovalent organic group. R ₆ and R ₇ each independently represent a group having —H, —NHD, —N (D) ₂ , —NHD, or a group having —N (D) ₂ . R 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 R ₅ , R ₆ and R ₇ has a t-butoxycarbonyl group in the group.

More preferred specific examples of the divalent organic group represented by the above formula (J-1) or (J-2) include the following formulas (J-1-a) to (J-1-d), It is a divalent organic group represented by (J-2-1). Boc represents a t-butoxycarbonyl group.

The tetracarboxylic acid component for obtaining the polymer (P1) can be used as the tetracarboxylic acid component for obtaining the polymer (P2). Specifically, the first tetracarboxylic acid component can be used from the viewpoint of enhancing the liquid crystal alignment. More preferably, the first tetracarboxylic acid component is used in an amount of 10 mol% or more based on the whole tetracarboxylic acid component used in the polymer (P2).

<Method for producing polymer (P1)>
The polymer (P1) is selected from the group consisting of a first polyimide precursor having an end blocked and an imidized polymer thereof, and a diamine component containing at least one diamine selected from specific diamines. And a tetracarboxylic acid component are subjected to a (condensation) polymerization reaction and then reacted with an end-capping agent.
Here, the polyimide precursor refers to a polyamic acid or a polyamic acid alkyl ester. In the liquid crystal aligning agent of the present invention, the polymer (P1) is preferably a terminal-capped polyimide precursor, and particularly preferably a terminal-capped polyamic acid.

In the embodiment of the present invention, the polymer (P1) is a polyimide precursor or an imidized polymer thereof by polymerizing a diamine component containing at least one diamine selected from specific diamines and a tetracarboxylic acid component. Is obtained, and further, the polyimide precursor or its imidized polymer is preferably reacted with an end-capping agent.
The polymer (P1) can also be obtained when the diamine component containing at least one diamine selected from the specific diamine and the tetracarboxylic acid component are polymerized or by supplying an end-capping agent during the polymerization. ..

The reaction between the diamine component and the tetracarboxylic acid component is usually performed in a solvent. The solvent used at that time is not particularly limited as long as it can dissolve the generated polyimide precursor. Specific examples of the solvent used in the reaction are shown below, but the solvent is not limited to these examples.
For example, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N, N-dimethylformamide, N, N-dimethylacetamide, 3-methoxy-N, N-dimethylpropanamide, 3- Examples include butoxy-N, N-dimethylpropanamide, dimethyl sulfoxide, or 1,3-dimethyl-imidazolidinone. If the polyimide precursor has high solvent solubility, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone or ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, diethylene glycol monomethyl ether, diethylene glycol mono Ethyl ether, diethylene glycol, propyl ether, or the like can be used.

-These solvents may be used alone or as a mixture. Furthermore, even a solvent that does not dissolve the polyimide precursor may be used as a mixture with the above solvent as long as the generated polyimide precursor does not precipitate. Further, since water in the solvent inhibits the polymerization reaction and causes hydrolysis of the generated polyimide precursor, it is preferable to use a dehydrated and dried solvent.

When the diamine component and the tetracarboxylic acid component are reacted in a solvent, the solution in which the diamine component is dispersed or dissolved in the solvent is stirred, and the tetracarboxylic acid component is added as it is or in the solvent after being dispersed or dissolved. Method, conversely, a method of dispersing a tetracarboxylic acid component in a solvent, or a method of adding a diamine component to a dissolved solution, a method of alternately adding a diamine component and a tetracarboxylic acid component to the reaction system, and the like, Any of these methods may be used. Further, when using a plurality of diamine components or tetracarboxylic acid components, respectively, may be reacted in a premixed state, may be reacted individually in sequence, further low molecular weight substances reacted separately May be mixed and reacted to form a polymer.

The temperature at which the diamine component and the tetracarboxylic acid component are polycondensed can be selected at any temperature from -20 to 150 ° C, but is preferably from -5 to 100 ° C. The reaction can be carried out at any concentration, but if the concentration is too low it will be difficult to obtain a high molecular weight polymer, and if the concentration is too high the viscosity of the reaction solution will be too high and uniform stirring will be difficult. .. Therefore, the concentration of the polymer is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The reaction can be performed at a high concentration in the initial stage and then a solvent can be added.
In the polymerization reaction for obtaining the polyimide precursor, the ratio of the total number of moles of the tetracarboxylic acid component to the total number of moles of the diamine component is preferably 0.8 to 1.2. Similar to the usual polycondensation reaction, the closer the molar ratio is to 1.0, the larger the molecular weight of the polyimide precursor produced.

The imidized polymer is a polyimide obtained by ring-closing a polyimide precursor, and in this polyimide, the ring-closing rate (also referred to as imidization rate) of the amic acid group (amide acid group) does not necessarily have to be 100%. However, it can be arbitrarily adjusted according to the purpose or purpose.
Examples of the method for imidizing the polyimide precursor include thermal imidization in which the solution of the polyimide precursor is heated as it is, and catalytic imidization in which a catalyst is added to the solution of the polyimide precursor.

When the polyimide precursor is thermally imidized in a solution, the temperature is preferably 100 to 400 ° C., more preferably 120 to 250 ° C., and the method is preferably performed while removing the water generated by the imidization reaction outside the system. .. Catalytic imidization of the polyimide precursor can be carried out by adding a basic catalyst and an acid anhydride to a solution of the polyimide precursor and stirring the mixture at -20 to 250 ° C, preferably 0 to 180 ° C.

The amount of the basic catalyst is preferably 0.5 to 30 mol times, more preferably 2 to 20 mol times the amic acid group, and the amount of acid anhydride is preferably 1 to 50 mol times the amic acid group. , And more preferably 3 to 30 times by mole.
Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine and the like. Of these, pyridine is preferable because it has an appropriate basicity to allow the reaction to proceed.
Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride and the like. Particularly, acetic anhydride is preferable because purification after the reaction is facilitated. The imidization ratio by catalytic imidization can be controlled by adjusting the amount of catalyst, reaction temperature, and reaction time.

When recovering the polyimide precursor or its imidized polymer produced from the reaction solution, the reaction solution may be poured into a solvent to cause precipitation. Examples of the solvent used for precipitation include methanol, ethanol, isopropyl alcohol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, toluene, benzene, water and the like. The polymer precipitated by pouring it into a solvent can be collected by filtration and then dried at normal temperature or under reduced pressure at room temperature or by heating. Further, by repeating the operation of re-dissolving the recovered polymer in a solvent and re-precipitating and recovering it 2 to 10 times, impurities in the polymer can be reduced. Examples of the solvent in this case include alcohols, ketones, hydrocarbons and the like. It is preferable to use three or more kinds of solvents selected from these, because the efficiency of purification is further improved.

In the present invention, when the polyimide precursor is a polyamic acid alkyl ester, a specific method for producing it is, for example, the method described in paragraphs [0054] to [0062] of International Publication WO 2011-115077. Is mentioned.

Next, in order to seal the acid terminal or amine terminal of the polyimide precursor or its imidized polymer, either during or after the production of the polyimide precursor or its imidized polymer, an end-capping agent is added. And react.
The amount of the end-capping agent used is not particularly limited, but is preferably 0.001 to 0.8 equivalents relative to 1 equivalent of amino groups in the diamine component involved in the polymerization reaction of the polyimide precursor or its imidized polymer. , 0.01 to 0.2 equivalents are more preferable.
Further, 0.001 to 0.8 equivalents are preferable with respect to 1 equivalent of the carboxyl group (or derivative structure thereof) in the tetracarboxylic acid component involved in the polymerization reaction of the polyimide precursor or its imidized polymer, and 0.01 It is preferably about 0.2 equivalent.
The reaction temperature for sealing the ends is preferably -50 to 150 ° C, more preferably -30 to 100 ° C. The reaction time is usually 0.1 to 100 hours.

<Method for producing polymer (P2)>
The polymer (P2) is selected from the group consisting of the second polyimide precursor and its imidized polymer, and is obtained by reacting a diamine component and a tetracarboxylic acid component. The reaction between the diamine component and the tetracarboxylic acid component is the same as that described in the method for producing the polymer (P1).

When the polymer (P2) is selected from the group consisting of a terminal-blocked polyimide precursor and its imidized polymer, either during or after the production of the polyimide precursor or its imidized polymer, or both. The end capping agent selected from the following formulas (R-1) to (R-2) may be reacted.

(R ₂ and R ₂ 'represent a monovalent organic group. N is an integer of 1-2.)

Specific examples of R ₂ and R ₂ ′ include methyl group, 9-fluorenylmethyl group, 2,2,2-trichloroethyl group, 2-trimethylsilylethyl group, 1,1-dimethylpropynyl group, 1-methyl- 1-phenylethyl group, 1-methyl-1- (4-biphenylyl) ethyl group, 1,1-dimethyl-2-haloethyl group, 1,1-dimethyl-2-cyanoethyl group, tert-butyl group, cyclobutyl group , 1-methylcyclobutyl group, 1-adamantyl group, vinyl group, allyl group, cinnamyl group, 8-quinolyl group, N-hydroxypiperidinyl group, benzyl group, p-nitrobenzyl group, 3,4-dimethoxy- Examples thereof include 6-nitrobenzyl group and 2,4-dichlorobenzyl group. Among them, tert-butyl group, 2,2,2-trichloroethyl group, 2-trimethylsilylethyl group, 1,1-dimethylpropynyl group, 1-methyl-1 -(4-biphenylyl) ethyl group, 1,1-dimethyl-2-haloethyl group, 1,1-dimethyl-2-cyanoethyl group, t-butyl group, cyclobutyl group, 1-methylcyclobutyl group, vinyl group, An allyl group, a cinnamyl group and an N-hydroxypiperidinyl group are more preferable, and a 1,1-dimethyl-2-haloethyl group, a 1,1-dimethyl-2-cyanoethyl group and a tert-butyl group are particularly preferable.

<Liquid crystal aligning agent>
The liquid crystal aligning agent of the present invention contains the polymer (P1) and, if necessary, the polymer (P2). The content of the polymer (P1) in the liquid crystal aligning agent is preferably 2 to 10% by mass, and more preferably 3 to 8% by mass in the liquid crystal aligning agent.
When the liquid crystal aligning agent contains the polymer (P2), the content of the polymer (P1) is 30 parts by mass or more based on 100 parts by mass of the total amount of the polymer (P1) and the polymer (P2). Is more preferable, 50 parts by mass or more is more preferable, 60 parts by mass or more is further preferable, and 70 parts by mass or more is most preferable.

The liquid crystal aligning agent of the present invention may contain a polymer other than the polymer (P1) and the polymer (P2). Examples of other polymers include cellulosic polymers, acrylic polymers, methacrylic polymers, polystyrene, polyamides, polysiloxanes and the like. The content of the other polymer is preferably 0.5 to 15 parts by mass, more preferably 1 to 10 parts by mass, based on 100 parts by mass of the total amount of the polymer (P1) and the polymer (P2). ..

The liquid crystal aligning agent usually contains an organic solvent, and the content of the organic solvent is preferably 70 to 99.9 mass% with respect to the liquid crystal aligning agent. This content can be appropriately changed depending on the coating method of the liquid crystal aligning agent and the target film thickness of the liquid crystal aligning film.
The organic solvent used for the liquid crystal aligning agent is preferably a solvent (also referred to as a good solvent) that dissolves the polymer (P1) and the polymer (P2). For example, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, methyl ethyl ketone , Cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, 3-methoxy-N, N-dimethylpropanamide, 3-butoxy-N, N-dimethylpropanamide and the like. Among them, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N, N-dimethylpropanamide, 3-butoxy-N, N-dimethylpropanamide or γ-butyrolactone is preferable.
The good solvent in the liquid crystal aligning agent of the present invention is preferably 20 to 99% by mass, more preferably 20 to 90% by mass, and particularly preferably 30 to 80% by mass based on the total amount of the solvent contained in the liquid crystal aligning agent. Is.

As the liquid crystal aligning agent of the present invention, a solvent (also referred to as a poor solvent) that improves the coating property and surface smoothness of the liquid crystal aligning film when the liquid crystal aligning agent is applied can be used. Specific examples are given below.
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, 1,2-butoxyethane, 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 mono Acetate, 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 acetate Glycol monoethyl ether, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, n-butyl lactate, isoamyl lactate, Examples thereof include diethylene glycol monoethyl ether and diisobutyl ketone (2,6-dimethyl-4-heptanone).

Among them, preferable solvent combinations include N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and ethylene glycol monobutyl ether, and N-methyl-2-pyrrolidone and γ-. Butyrolactone and propylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and 4-hydroxy-4-methyl-2-pentanone and diethylene glycol diethyl ether, N- Methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether and 2,6-dimethyl-4-heptanone, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether and diisopropyl ether, N-methyl-2 -Pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether and 2,6-dimethyl-4-heptanol, N-methyl-2-pyrrolidone, γ-butyrolactone and dipropylene glycol dimethyl ether and the like can be mentioned. The amount of the poor solvent is preferably 1 to 80% by mass, more preferably 10 to 80% by mass, and particularly preferably 20 to 70% by mass, based on the whole solvent contained in the liquid crystal aligning agent. The type and content of such a solvent are appropriately selected according to the liquid crystal alignment agent coating device, coating conditions, coating environment, and the like.

The liquid crystal aligning agent of the present invention includes a dielectric for the purpose of changing electrical properties such as the dielectric constant and conductivity of the liquid crystal aligning film, a silane coupling agent for improving the adhesion between the liquid crystal aligning film and the substrate, and a liquid crystal. A crosslinkable compound for the purpose of increasing the hardness and the density of the film when it is formed into an alignment film, and further an imidization accelerator for the purpose of efficiently promoting imidization by heating the polyimide precursor when baking the coating film. You may make it contain.

Examples of the compound that improves the adhesion between the liquid crystal alignment film and the substrate include a functional silane-containing compound and an epoxy group-containing compound, and examples thereof include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and 3-aminopropyltriethoxysilane. Glycidoxypropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 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-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, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol Diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether 1,3,5, 6-tetraglycidyl-2,4-hexanediol, N, N, N ', N',-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, or Examples thereof include N, N, N ', N',-tetraglycidyl-4,4'-diaminodiphenylmethane and the like.

Further, the liquid crystal aligning agent of the present invention may contain the following additives (CL-1) to (CL-15) in order to increase the mechanical strength of the liquid crystal aligning film.

The above additive is preferably 0.1 to 30 parts by mass with respect to 100 parts by mass of the polymer component contained in the liquid crystal aligning agent. More preferably, it is 0.5 to 20 parts by mass.

<Method for producing liquid crystal alignment film>
The liquid crystal alignment film is obtained by forming a film by coating the above liquid crystal aligning agent on a substrate, preferably drying and then firing. As the substrate, a substrate having high transparency is preferable, and as the material thereof, glass, ceramics such as silicon nitride, plastic such as acrylic resin or polycarbonate, and the like can be used. It is preferable to use a substrate on which an ITO (Indium Tin Oxide) electrode for driving the liquid crystal is formed as the substrate from the viewpoint of simplifying the process. Further, in the reflective liquid crystal display element, an opaque material such as a silicon wafer can be used for the substrate on one side, and a light-reflecting material such as aluminum can be used for the electrode.

As a method for forming a film on a substrate from a liquid crystal aligning agent, screen printing, offset printing, flexo printing, inkjet method, etc. can be used, and also dip method, roll coater method, slit coater method, spinner method, spray method, etc. It can be used according to the purpose.
After forming the film of the liquid crystal aligning agent on the substrate, the film is preferably heated at 30 to 120 ° C., more preferably at 50 to 120 ° C. by a heating means such as a hot plate, a heat circulation type oven, an IR (infrared) type oven. It is preferable to evaporate the solvent by drying treatment for 1 minute to 10 minutes, more preferably 1 minute to 5 minutes.

When the thermal imidization of the imide precursor in the polymer is carried out, the coating film obtained from the liquid crystal aligning agent is then preferably heated at 120 to 250 ° C., more preferably 150 ° C. by the same heating means as in the above drying treatment. It is baked at ~ 230 ° C. The firing time varies depending on the firing temperature, but is preferably 5 minutes to 1 hour, more preferably 5 minutes to 40 minutes.

The thickness of the coating film after the baking treatment is not particularly limited, but if it is too thin, the reliability of the liquid crystal display element may decrease, and if it is too thick, the electric resistance of the obtained liquid crystal alignment film increases, so that it is 5 to 300 nm. Is preferred, and 10 to 200 nm is more preferred.
After the baking treatment, the obtained coating film is oriented. Examples of the alignment treatment method include a rubbing treatment method and a photo-alignment treatment method.

As a specific example of the photo-alignment treatment, the surface of the coating film is irradiated with radiation polarized in a certain direction. Ultraviolet rays or visible rays having a wavelength of 100 to 800 nm can be used as the radiation. Among them, ultraviolet rays having a wavelength of 100 to 400 nm are preferable, and ultraviolet rays having a wavelength of 200 to 400 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.

At least one treatment selected from the group consisting of heat treatment and contact treatment with a solvent may be further applied to the film subjected to the orientation treatment.
The heat treatment after the orientation treatment can be performed by the same heating means as the above-mentioned drying treatment and firing treatment, and is preferably performed at 180 to 250 ° C, more preferably 180 to 230 ° C. When the temperature of the heat treatment is performed within the above range, the contrast of the liquid crystal display element obtained by the obtained liquid crystal alignment film can be increased. The time of the heat treatment varies depending on the heating temperature, but is preferably 5 minutes to 1 hour, more preferably 5 to 40 minutes.

The solvent used for the contact treatment with the solvent is not particularly limited as long as it is a solvent that dissolves impurities and the like attached to the liquid crystal alignment film.
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- Methyl methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, cyclohexyl acetate and the like can be mentioned. 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. These solvents may be one type or two or more types.

The contact treatment includes dipping treatment and spraying treatment (also referred to as spraying treatment). The treatment time in these treatments is preferably 10 seconds to 1 hour, and particularly, an embodiment in which the immersion treatment is performed for 1 to 30 minutes can be mentioned. The temperature at the time of contact treatment may be room temperature or warming, but is preferably 10 to 80 ° C., and 20 to 50 ° C. is mentioned. At the time of contact treatment, ultrasonic treatment or the like may be further performed if necessary.

After the contact treatment, rinsing (also referred to as rinsing) or drying with a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone may be performed. At that time, either one of rinsing and drying or both of them may be performed. The drying temperature is preferably 50 to 150 ° C, and may be 80 to 120 ° C. The drying time is preferably 10 seconds to 30 minutes, more preferably 1 to 10 minutes.
After the contact treatment with the solvent, the heat treatment after the orientation treatment may be performed. With such a mode, a liquid crystal alignment film having excellent liquid crystal alignment can be obtained.

<Liquid crystal display element>
The liquid crystal alignment film of the present invention can be applied to various driving modes such as a TN method, an STN method, an IPS method, an FFS method, a VA method, an MVA method and a PSA method. It is suitable as a liquid crystal alignment film for an electric field type liquid crystal display element, and is particularly useful for an FFS type liquid crystal display element. The liquid crystal display device of the present invention is a device obtained by preparing a liquid crystal cell by a known method after obtaining a substrate with a liquid crystal alignment film obtained from the above liquid crystal aligning agent.
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. Note that a liquid crystal display element having an active matrix structure in which a switching element such as a TFT is provided in each pixel portion forming an 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 film made of SiO ₂ —TiO ₂ formed by the sol-gel method. Next, under the above conditions, a liquid crystal alignment film is formed on each substrate, and one substrate is overlaid with the other liquid crystal alignment film surface facing each other. Glue with. In order to control the substrate gap, it is usually preferable to mix a spacer in the sealant. Further, it is preferable that spacers for controlling the substrate gap are also scattered on the in-plane portion where the sealant is not provided. It is preferable that a part of the sealant is provided with an opening that can be filled with liquid crystal from the outside.

After that, a liquid crystal material is injected into a space surrounded by the two substrates and the sealant through an opening provided in the sealant. Next, this opening is sealed with an adhesive. Examples of the injection include a vacuum injection method and a method utilizing a capillary phenomenon in the atmosphere, and an ODF (One Drop Fill) method may be used. The liquid crystal material may have either positive or negative dielectric anisotropy. In the present invention, a liquid crystal having a negative dielectric anisotropy is preferable from the viewpoint of liquid crystal orientation, but it can be used properly according to the application.
After the liquid crystal material is injected into the liquid crystal cell, the polarizing plate is installed. Specifically, it is preferable to attach a pair of polarizing plates to the surfaces of the two substrates opposite to the liquid crystal layer.

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

NMP: N-methyl-2-pyrrolidone, GBL: γ-butyrolactone BCS: butyl cellosolve

[viscosity]
Using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.), the sample amount was 1.1 mL, the cone rotor TE-1 (1 ° 34 ', R24), and the temperature was 25 ° C.
[Molecular weight]
The number average molecular weight (Mn) and the weight average molecular weight (Mw) were calculated as a polyethylene oxide conversion value by measuring with a GPC (normal temperature gel permeation chromatography) device.
GPC device: Shodex (GPC-101), column: Shodex (KD803, KD805 in series), column temperature: 50 ° C, eluent: N, N-dimethylformamide (lithium bromide-water as an additive) The solvate (LiBr.H ₂ O) contains 30 mmol / L, phosphoric acid / anhydrous crystal (o-phosphoric acid) contains 30 mmol / L, and tetrahydrofuran (THF) contains 10 ml / L.), Flow rate: 1.0 ml / L. Standard sample for preparing calibration curve: TSK standard polyethylene oxide (weight average molecular weight (Mw) about 900,000, 150,000, 100,000, 30,000) manufactured by Tosoh Corporation, and polyethylene glycol (peak manufactured by Polymer Laboratory) Top molecular weight (Mp) about 12,000, 4,000, 1,000). In order to avoid overlapping peaks, the measurement was performed using a sample in which four kinds of 900,000, 100,000, 12,000 and 1,000 were mixed, and three kinds of 150,000, 30,000 and 4,000. Two of the mixed samples were measured separately.

[Production of liquid crystal cell]
A liquid crystal cell having a configuration of a fringe field switching (FFS) mode liquid crystal display device 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 a 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 is arranged as a third layer 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 counter electrode of the first layer and the pixel electrode of the third layer are electrically insulated by the action of the SiN film of the second layer.
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. Since the pixel electrode that forms each pixel is configured by arranging a plurality of bent "dogleg" -shaped electrode elements in the central portion, 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, after filtering the liquid crystal aligning agent with a filter having a pore size of 1.0 μm, spin coating is performed on the prepared substrate with electrodes and a glass substrate having a columnar spacer with a height of 4 μm on which an ITO film is formed on the back surface. It was applied by the method. After drying for 2 minutes on a hot plate at 80 ° C., baking was performed for 30 minutes in a hot air circulation type oven at 230 ° C. to form a coating film having a film thickness of 100 nm. This coating film surface was irradiated with linearly polarized ultraviolet light having a wavelength of 254 nm having an extinction ratio of 10: 1 or more through a polarizing plate. This substrate was further baked in a hot air circulation type oven at 230 ° C. for 30 minutes to obtain a substrate with a liquid crystal alignment film. 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. Set the above two substrates as a set, print the sealant on the substrate, and bond the other substrate so that the liquid crystal alignment film surfaces face each other and the alignment direction is 0 °, and then the sealant is cured. Then, an empty cell was produced. Liquid crystal MLC-3019 (manufactured by Merck & Co., Inc.) was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an FFS driven liquid crystal cell. Then, the obtained liquid crystal cell was heated at 110 ° C. for 1 hour and left overnight, and then used for each evaluation.

[Afterimage evaluation by long-term AC drive]
A liquid crystal cell having the same structure as the liquid crystal cell used for the above-mentioned afterimage evaluation was prepared.
Using this liquid crystal cell, an AC voltage of ± 5 V was applied for 120 hours at a frequency of 60 Hz in a constant temperature environment of 60 ° C. Then, the pixel electrode of the liquid crystal cell and the counter electrode were short-circuited and left at room temperature for one day.
After leaving, the liquid crystal cell is placed between two polarizing plates arranged so that their polarization axes are orthogonal to each other, and the backlight is turned on with no voltage applied so that the brightness of the transmitted light is minimized. The arrangement angle of the liquid crystal cell was adjusted. Then, the rotation angle when the liquid crystal cell was rotated from the angle where the second region of the first pixel was darkest to the angle where the first region was darkest was calculated as the angle Δ. Similarly, for the second pixel, the same angle Δ was calculated by comparing the second area and the first area.

<Synthesis Example 1> (polyamic acid with unterminated ends)
In a 3 L four-necked flask equipped with a stirrer and a nitrogen inlet tube, 17.30 g (159.98 mmol) of diamine DA-1, 58.63 g (240.0 mmol) of diamine DA-2 and 76. 89 g (240.0 mmol) and diamine DA-4 (54.63 g, 159.99 mmol) were weighed out, NMP (2458.13 g) was added, and the mixture was dissolved by stirring while feeding nitrogen. While stirring this diamine solution, 171.27 g (764.02 mmol) of tetracarboxylic acid dianhydride TA-1 was added, and further NMP was added so that the solid content concentration became 12% by mass, and the mixture was added at 20 ° C. at 20 ° C. After stirring for a time, a polyamic acid solution (PAA-1) was obtained.
The viscosity of this polyamic acid solution was 426 mPa · s. The molecular weight of this polyamic acid was Mn = 12,380 and Mw = 33,250.

<Synthesis example 2> (polyamic acid having unsealed ends)
5.29 g (26.98 mmol) of tetracarboxylic acid dianhydride TA-2 was weighed out in a 100 mL four-necked flask equipped with a stirrer and a nitrogen introducing tube, 80.13 g of NMP was added, and the mixture was stirred while sending nitrogen. Dissolved. While stirring this carboxylic dianhydride solution, 2.96 g (14.86 mmol) of diamine DA-5, 2.28 g (5.41 mmol) of diamine DA-6, and 1.61 g (diamine DA-7) were obtained. (5.43 mmol), NMP was further added so that the solid content concentration was 12% by mass, and the mixture was stirred at 40 ° C. for 20 hours to obtain a polyamic acid solution (PAA-2).
The viscosity of this polyamic acid solution was 437 mPa · s. The molecular weight of this polyamic acid was Mn = 16,331 and Mw = 35,853.

<Synthesis example 3> (polyamic acid with unsealed ends)
2.98 g (14.96 mmol) of diamine DA-5, 2.11 g (5.00 mmol) of diamine DA-6, and 1 of diamine DA-7 were placed in a 100 mL four-necked flask equipped with a stirrer and a nitrogen introducing tube. .49 g (4.99 mmol) was weighed out, 74.16 g of NMP was added, and the mixture was dissolved by stirring while feeding nitrogen. While stirring this diamine solution, 4.64 g (23.66 mmol) of tetracarboxylic dianhydride TA-2 was added, and further NMP was added so that the solid content concentration became 12% by mass, and 20 ° C. at 40 ° C. After stirring for a time, a polyamic acid solution (PAA-3) was obtained.
The viscosity of this polyamic acid solution was 443 mPa · s. The molecular weight of this polyamic acid was Mn = 12,155 and Mw = 35,725.

<Synthesis Example 4> (Polyamic acid having a terminal blocked)
Into a 50 mL Erlenmeyer flask, 20.0 g of polyamic acid (PAA-2) was weighed out, and 0.035 g (0.38 mmol) of the terminal blocking agent MA-1 was added to 1 equivalent of amino groups in the diamine involved in the polymerization reaction. 0.04 eq) was added and stirred at 40 ° C. for 20 hours to obtain a polyamic acid solution (PAA-4). The acid end of the polyamic acid solution (PAA-4) was blocked.

<Synthesis Examples 5 to 8> (Polyamic acid having a terminal blocked)
The polyamic acid solution and the terminal blocking agent shown in Table 2 below were used, and each was carried out in the same manner as in Synthesis Example 4 to obtain the polyamic acid solutions (PAA-5) to (PAA-8) shown in Table 2 below. Got The polyamic acid solution (PAA-5) was capped at the acid end, and the polyamic acid solutions (PAA-6) to (PAA-8) were capped at the amine end.

(Component 1: Component 2 blend ratio (mass ratio) is 5: 5 liquid crystal aligning agent)
<Example 1>
2.29 g of 12 mass% polyamic acid solution (PAA-4) (component 1) and 2.29 g of 12 mass% polyamic acid solution (PAA-1) (component 2) were placed in a 50 ml Erlenmeyer flask, and NMP of 2.41 g, 3.00 g of BCS was added and mixed at 25 ° C. for 2 hours to obtain a liquid crystal aligning agent (A1). No abnormalities such as turbidity or precipitation were observed in this liquid crystal aligning agent, and it was confirmed that the liquid crystal aligning agent was a uniform solution.

<Examples 4, 7, 10, 13>
A liquid crystal aligning agent (A4) was prepared in the same manner as in Example 1 except that polyamic acid solutions (PAA-5) to (PAA-8) were used instead of the polyamic acid solution (PAA-4). (A7), (A10), and (A13) were obtained.
<Comparative Examples 1 and 4>
A liquid crystal aligning agent (B1) was obtained in the same manner as in Example 1 except that polyamic acid solutions (PAA-2) to (PAA-3) were used instead of the polyamic acid solution (PAA-4). (B4) was obtained.

(Component 1: Component 2 blending ratio (mass ratio) is 6: 4 liquid crystal aligning agent)
<Example 2>
2.75 g of 12% by mass polyamic acid solution (PAA-4) (component 1) and 1.83 g of 12% by mass polyamic acid solution (PAA-1) (component 2) were placed in a 50 ml Erlenmeyer flask, and NMP 2.41 g, 3.00 g of BCS was added and mixed at 25 ° C. for 2 hours to obtain a liquid crystal aligning agent (A2). No abnormalities such as turbidity or precipitation were observed in this liquid crystal aligning agent, and it was confirmed that the liquid crystal aligning agent was a uniform solution.

<Examples 5, 8, 11, 14>
A liquid crystal aligning agent (A5) was prepared in the same manner as in Example 2 except that polyamic acid solutions (PAA-5) to (PAA-8) were used instead of the polyamic acid solution (PAA-4). (A8), (A11), and (A14) were obtained.
<Comparative examples 2 and 5>
A liquid crystal aligning agent (B2) was obtained in the same manner as in Example 2 except that the polyamic acid solutions (PAA-2) to (PAA-3) were used instead of the polyamic acid solution (PAA-4). (B5) was obtained.

(Component 1: Component 2 blending ratio (mass ratio) is 7: 3 liquid crystal aligning agent)
<Example 3>
3.21 g of 12% by mass polyamic acid solution (PAA-4) (component 1) and 1.38 g of 12% by mass polyamic acid solution (PAA-1) (component 2) were placed in a 50 ml Erlenmeyer flask, and NMP 2.41 g, 3.00 g of BCS was added and mixed at 25 ° C. for 2 hours to obtain a liquid crystal aligning agent (A3). No abnormalities such as turbidity or precipitation were observed in this liquid crystal aligning agent, and it was confirmed that the liquid crystal aligning agent was a uniform solution.

<Examples 6, 9, 12, 15>
A liquid crystal aligning agent (A6) was prepared in the same manner as in Example 3 except that polyamic acid solutions (PAA-5) to (PAA-8) were used instead of the polyamic acid solution (PAA-4). (A9), (A12) and (A15) were obtained.
<Comparative Examples 3 and 6>
A liquid crystal aligning agent (B3) was obtained in the same manner as in Example 3 except that polyamic acid solutions (PAA-2) to (PAA-3) were used instead of the polyamic acid solution (PAA-4). (B6) was obtained.

(Result of afterimage evaluation by long-term AC drive)
<Example 16>
After filtering the liquid crystal aligning agent (A1) obtained in Example 1 with a filter having a pore size of 1.0 μm, the prepared substrate with electrodes and a columnar spacer having a height of 4 μm on which an ITO film was formed on the back surface were prepared. The glass substrate was coated by spin coating. After drying for 2 minutes on a hot plate at 80 ° C., baking was performed for 30 minutes in a hot air circulation type oven at 230 ° C. to form a coating film having a film thickness of 100 nm. This coating film surface was irradiated through a polarizing plate with 0.3 J / cm ² of linearly polarized ultraviolet light having a wavelength of 254 nm with an extinction ratio of 26: 1. This substrate was baked for 30 minutes in a hot air circulation type oven at 230 ° C. to obtain a substrate with a liquid crystal alignment film.

A set of the above-mentioned two substrates is printed, a sealant is printed on the substrates, and the other substrate is bonded so that the liquid crystal alignment film surfaces face each other and the alignment direction is 0 °, and then the seal is made. The agent was cured to produce an empty cell. Liquid crystal MLC-3019 (manufactured by Merck & Co., Inc.) was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an FFS driven liquid crystal cell. After that, the obtained liquid crystal cell was heated at 110 ° C. for 1 hour and left overnight, and afterimage evaluation by long-term AC drive was performed. The value of the angle Δ of this liquid crystal cell after long-term AC driving was 0.26 degrees.

<Examples 17 to 21, Comparative Examples 7 to 9>
An FFS-driving liquid crystal cell was produced in the same manner as in Example 16 except that the liquid crystal aligning agents A2 to A5 and B1 to B3 shown in Table 3 were used instead of the liquid crystal aligning agent (A1). Afterimage evaluation was performed by long-term AC drive. Table 4 shows the values of the angle Δ of the liquid crystal cell after the long-term AC driving.

<Examples 22 to 30, Comparative Examples 10 to 12>
An FFS-driving liquid crystal cell was prepared in the same manner as in Example 16 except that the liquid crystal aligning agents A7 to A15 and B4 to B6 shown in Table 4 were used instead of the liquid crystal aligning agent (A1). Afterimage evaluation was performed by long-term AC drive. Table 5 shows the value of the angle Δ of the liquid crystal cell after the long-term AC driving in each case.

In Table 4, comparing Comparative Example 7 with Examples 16 and 19, Comparative Example 8 with Examples 17 and 20, and Comparative Example 9 with Examples 18 and 21, when blending the polyamic acid whose acid terminal is modified with monoamine It can be seen that the afterimage tends to decrease due to the AC drive.
Further, in Table 5, when comparing Comparative Example 10 with Examples 22, 25, 28, Comparative Example 11 with Examples 23, 26, 29, and Comparative Example 12 with Examples 24, 26, 30, respectively, the amine terminal was compared with the carboxyl group. It was confirmed that when blending a polyamic acid modified with an acid anhydride, the afterimage due to long-term AC drive tends to decrease.
Taking the difference between the Δ values of the comparative example and the example having the same blend ratio, the difference between the Δ value of the comparative example and the Δ value of the example tended to increase as the blend ratio of the component 1 was higher. .. Therefore, this method is particularly useful when it is desired to increase the ratio of component 1.

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 a liquid crystal display element of the IPS drive system or the FFS drive system, and thus has an afterimage characteristic. A liquid crystal display element of excellent IPS drive system or FFS drive system can be obtained. Therefore, it is used particularly in a liquid crystal display device that requires high display quality.
In addition, the entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2018-214005 filed on November 14, 2018 are cited herein as disclosure of the specification of the present invention. , Take in.

Claims (13)

1. At least one diamine selected from the group consisting of a diamine containing a partial skeleton represented by any of the following formulas (ND-1) to (ND-4) and a diamine represented by (ND-5): A diamine component containing and a tetracarboxylic acid component are polymerized, and obtained by reacting with an end-capping agent, and the end-capped first polyimide precursor and a group consisting of its imidized polymer A liquid crystal aligning agent comprising at least one polymer (P1) selected.
   

   

   (R ¹ , R ²¹ , and R ²² each independently represent a hydrogen atom or a methyl group, and R ⁵¹ and R ⁵² each independently represent a hydrogen atom or a methyl group. S _p3 and S _p4 are , Each independently represents a divalent organic group. A ₅ represents a single bond or a divalent organic group.)
2. The liquid crystal aligning agent according to claim 1, wherein the tetracarboxylic acid component contains a tetracarboxylic dianhydride represented by the following formula (1).
   

   

   (X represents a tetravalent organic group selected from the following formulas (X-1) to (X-14).)
   

   

   (X and y each independently represent a single bond, methylene, ethylene, propylene, ether, carbonyl, ester, phenylene, sulfonyl or amide group. Z ¹ to Z ⁴ are each independently hydrogen atom, methyl Represents a group, an ethyl group, a propyl group, a chlorine atom or a phenyl group, j and k are integers of 0 or 1, m is an integer of 0 to 5, and * represents a bond.)
3. The liquid crystal aligning agent according to claim 2, wherein the content of the tetracarboxylic dianhydride represented by the formula (1) is 5 mol% or more of the total tetracarboxylic acid component.
4. The content of at least one diamine selected from the group consisting of diamines containing the partial skeletons represented by the above formulas (ND-1) to (ND-4) and diamines represented by (ND-5) is The liquid crystal aligning agent according to any one of claims 1 to 3, which is 5 mol% or more of the entire diamine component.
5. The diamine component is at least two diamines selected from the group consisting of diamines containing the partial skeletons represented by the formulas (ND-1) to (ND-4) and diamines represented by (ND-5). The liquid crystal aligning agent according to any one of claims 1 to 4, which is contained.
6. 6. The diamine having a partial skeleton represented by (ND-1) is a diamine represented by the following formula (ND-1-1) or (ND-1-2). The liquid crystal aligning agent according to item 1.
   

   

   (R ¹ and R ² each independently represent a hydrogen atom or a methyl group, R ¹¹ and R ²² each independently represent a single bond, or * 1-R ³ -Ph- * 2, and R ³ is A single bond, a divalent organic group selected from —O—, —COO—, —OCO—, — (CH ₂ ) _l —, —O (CH ₂ ) _m O—, —CONH—, and —NHCO— Represents (l and m represent an integer of 1 to 5) * 1 represents a site bonded to the benzene ring in formula (ND-1-1) or (ND-1-2), and * 2 represents formula (ND). (ND-1-1) or (ND-1-2) represents a site that binds to an amino group, Ph represents a phenylene group, and n is an integer of 1 to 3.)
7. The at least one polymer (P2) selected from the group consisting of a second polyimide precursor and its imidized polymer, which is obtained by reacting a diamine component and a tetracarboxylic acid component, is further contained. 7. The liquid crystal aligning agent according to any one of items 6 to 6.
8. The diamine component which is a raw material of the polymer (P2) contains at least one diamine selected from the group consisting of the following formula (3), the following formula (4) and the following formula (5). The liquid crystal aligning agent described.
   

   

   (A ₁ and A ₄ each independently represent a single bond or a divalent organic group, 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 monovalent organic group having 1 to 20 carbon atoms, A ₃ represents a divalent organic group, a is an integer of 1 to 4, and when a is 2 or more, the structure of A ₂ is the same. B and c are each independently an integer of 1 to 2, and d is an integer of 0 or 1.)
9. The diamine component which is a raw material of the polymer (P2) is represented by the following formulas (DA-3-1), (DA-4-1) to (DA-4-23), and (DA-5-1) to (DA-5-1). The liquid crystal aligning agent according to any one of claims 7 to 8, containing at least one diamine selected from the group consisting of DA-5-3).
   

   

   

   

   
10. The liquid crystal aligning agent according to any one of claims 1 to 9, wherein the terminal blocking agent is an acid anhydride or a monoamine.
11. The content of the polymer (P1) is 30 parts by mass or more based on 100 parts by mass of the total amount of the polymer (P1) and the polymer (P2). The liquid crystal aligning agent according to item 1.
12. A liquid crystal alignment film obtained by applying polarized ultraviolet light to a film obtained by applying the liquid crystal alignment agent according to any one of claims 1 to 11 and baking it.
13. A liquid crystal display device comprising the liquid crystal alignment film according to claim 12.