WO2021246431A1

WO2021246431A1 - Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element

Info

Publication number: WO2021246431A1
Application number: PCT/JP2021/020937
Authority: WO
Inventors: 達也結城; 玲久小西; 雄介山本; 崇仲井; 圭太慈道
Original assignee: 日産化学株式会社
Priority date: 2020-06-05
Filing date: 2021-06-02
Publication date: 2021-12-09
Also published as: KR20230021645A; JPWO2021246431A1; TW202208601A; CN115885211A

Abstract

Provided is a liquid crystal alignment agent that can be suitably used for a liquid crystal alignment film having high film strength and for a liquid crystal display element in which AC afterimages are suppressed, and that does not precipitate solid content when being stored at a low temperature. Further provided are a liquid crystal alignment film obtained from said liquid crystal alignment agent, and a liquid crystal display element having said liquid crystal alignment film.　The liquid crystal alignment agent contains a component (A) and a component (B). Component (A): A polymer (A) having the ability to align liquid crystals. Component (B): A hydroxyalkylamide compound (B) represented by formula (1). (R represents a C1-6 alkyl group, R₁ and R₂ each independently represent a hydrogen atom or a C1-6 monovalent organic group, and A represents a C1-30 divalent organic group.)

Description

Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element

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

Conventionally, liquid crystal displays have been widely used as display units for personal computers, smartphones, mobile phones, television receivers, and the like. The liquid crystal display device includes, for example, a liquid crystal layer sandwiched between an element substrate and a color filter substrate, a pixel electrode and a common electrode that apply an electric field to the liquid crystal layer, and an alignment film that controls the orientation of liquid crystal molecules in the liquid crystal layer. It is equipped with a thin film transistor (TFT) or the like for switching an electric signal supplied to a pixel electrode. As the driving method of the liquid crystal molecule, a vertical electric field method such as a TN (Twisted Nematic) method and a VA (Vertical Alignment) method, and a horizontal electric field method such as an IPS (In-Plane Switching) method and an FFS (Fringe Field Switching) method are used. Are known.

Currently, the most widely used liquid crystal alignment film in industry is a film made of a polymer typified by a polyamic acid and / or an imidized polyimide formed on an electrode substrate, and the surface of the film is made of cotton or nylon. , It is manufactured by performing a so-called rubbing process of rubbing in one direction with a cloth such as polyester. The rubbing process is a simple and highly productive industrially useful method. However, with the increase in performance, definition, and size of liquid crystal display elements, scratches on the surface of the alignment film generated by the rubbing process, dust generation, the effects of mechanical force and static electricity, and the in-plane alignment process Various problems such as non-uniformity of the above have been clarified. As an orientation treatment method instead of the rubbing treatment, a photo-alignment method for imparting a liquid crystal alignment ability by irradiating with polarized radiation is known. As the photoalignment method, a method using a photoisomerization reaction, a method using a photocrosslinking reaction, a method using a photodecomposition reaction, and the like have been proposed (see, for example, Non-Patent Document 1 and Patent Document 1).

In recent years, large-screen, high-definition LCD TVs have become the mainstream, and small display terminals such as smartphones, tablet PCs, and car navigation systems have become widespread, and the demand for higher quality LCD display elements has increased even more than before. ing. As a reliability test of liquid crystal display elements for mobile applications such as smartphones and in-vehicle applications such as car navigation systems, a panel vibration test may be conducted. In this vibration test, it is required that defects such as bright spots do not occur. In order to obtain a liquid crystal display element that does not cause defects after the vibration test, for example, a method of increasing the mechanical strength of the liquid crystal alignment film can be considered. As a method for improving the mechanical strength of the liquid crystal alignment film, particularly the film strength, a method of adding a cross-linking agent to the liquid crystal alignment agent can be mentioned.
Further, in the IPS system and the FFS drive system, the stability of the liquid crystal orientation is also important. If the orientation stability is small, the liquid crystal does not return to the initial state when the liquid crystal is driven for a long time, which causes a decrease in contrast and burn-in (hereinafter referred to as AC afterimage).
As a means for solving these problems, a liquid crystal alignment agent containing a specific polyimide component and a specific hydroxyalkylamide compound has been proposed (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 9-297313 WO2018 / 092811 Publication

The liquid crystal alignment agent is usually stored in a very low temperature environment (for example, at −20 ° C.) from the time of manufacture to the time of shipment in order to prevent deterioration of the polymer.
On the other hand, in the study by the present inventors, when the hydroxyalkylamide compound described in Patent Document 2 is added to the liquid crystal alignment agent, the film strength of the obtained liquid crystal alignment film is improved and the AC afterimage is suppressed. However, it was found that the solid content contained in the liquid crystal alignment agent was precipitated during storage at a low temperature.
Once deposited, the solid content is difficult to redissolve, which may cause problems such as printing defects in the manufacturing process of the liquid crystal display element. The cause of such solid content precipitation is not clear, but it is presumed that the high polarity of the hydroxyalkylamide compound used in the liquid crystal alignment agent is one of the causes. Therefore, there is a demand for a liquid crystal alignment agent that does not cause precipitation of solid content even during frozen storage.

Based on the above, the present invention is a liquid crystal alignment agent that can be suitably used for a liquid crystal alignment film having high film strength and a liquid crystal display element in which AC afterimage is suppressed, and a liquid crystal in which solid content does not precipitate during low temperature storage. It is intended to provide an orienting agent. Further, it is an object of the present invention to provide a liquid crystal alignment film obtained from the liquid crystal alignment agent and a liquid crystal display element having the liquid crystal alignment film.

As a result of diligent research to achieve the above-mentioned problems, the present inventor has found that a liquid crystal aligning agent containing a specific hydroxyalkylamide compound is extremely effective for achieving the above-mentioned object, and the present invention. Was completed.

The present invention includes the following aspects.
[1] A liquid crystal alignment agent containing the following component (A) and component (B).
(A) Component: Polymer (A) having the ability to orient the liquid crystal display
Component (B): Hydroxyalkylamide compound (B) represented by the following formula (1)

(R is an alkyl group having 1 to 6 carbon atoms, R ₁ and R ₂ are independently hydrogen atoms or monovalent organic groups having 1 to 6 carbon atoms, and A is a divalent organic group having 1 to 30 carbon atoms. Represents.)

Another aspect of the present invention includes the following aspects.
[1] A liquid crystal alignment agent containing the following components (A') and (B').
(A') component: Polymer (A') having the ability to orient the liquid crystal display.
Component (B'): Hydroxyalkylamide compound (B') represented by the following formula (1')

(R 'is a group _{_{"* -C (R 2') 2}} -C (R 1 ') 2 -OH " (* represents a bond .R _{_1',} R ₂ _'each independently represent a hydrogen atom or It represents a monovalent organic group having 1 to 6 carbon atoms.), And a plurality of R's may be the same or different. N is an integer of 1 to 30. L 1 _'is a divalent organic group having 1 to 10 carbon atoms, more L _1' may be the same or different.)

According to the present invention, a liquid crystal alignment agent that can be suitably used for a liquid crystal alignment film having high film strength and a liquid crystal display element in which AC afterimage is suppressed, and a liquid crystal alignment agent in which solid content does not precipitate during low temperature storage, and the same. It is possible to provide a liquid crystal alignment film obtained from a liquid crystal alignment agent and a liquid crystal display element having the liquid crystal alignment film.

Hereinafter, a liquid crystal alignment agent containing a specific hydroxyalkylamide compound, a liquid crystal alignment film formed by using the liquid crystal alignment agent, and a liquid crystal display element having the liquid crystal alignment film will be described in detail. The description of the constituent elements is an example as an embodiment of the present invention, and is not specified in these contents.
In the following description, the description of "(meth) acrylic" refers to both acrylic and methacrylic. Further, examples of the "halogen atom" include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like.

(Liquid crystal alignment agent)
The liquid crystal aligning agent of the present invention is a polymer (A) (also referred to as a component (A) in the present invention) or a polymer (A') (also referred to as a component (A') in the present invention) having the ability to orient the liquid crystal. ). Examples of the polymer (A') include compounds similar to those of the polymer (A), including preferable specific examples.
In addition, one aspect of the liquid crystal alignment agent of the present invention is the polymer (A) and the hydroxyalkylamide compound (B) represented by the formula (1) (also referred to as the component (B) in the present invention). contains.
In addition, another aspect of the liquid crystal alignment agent of the present invention is the hydroxyalkylamide compound (B') represented by the above polymer (A') and the above formula (1') (in the present invention, (B'). Also called an ingredient).

<(A) component, (A') component>
The liquid crystal alignment agent of the present invention contains a polymer having the ability to orient the liquid crystal as in the known one, but the polymer is not particularly limited as long as it has the ability to orient the liquid crystal.
Examples of such polymers include polyimide precursors, polyimides of polyimide precursors, polyimides, acrylic polymers, methacrylic polymers, acrylamide polymers, methacrylamide polymers, polystyrenes, polysiloxanes, polyamides, polyesters, polyurethanes, polycarbonates, and polyureas. , Polyphenol (novolak resin), maleimide polymer, polymer introduced with a compound having an isocyanuric acid skeleton or a triazine skeleton, and the like.

Examples of the raw materials for producing these polymers include the following.
When the polymer is a polyimide precursor such as polyamic acid or polyamic acid ester or polyimide, at least one compound (preferably tetracarboxylic acid dianhydride) selected from tetracarboxylic acid or a derivative thereof and diamine can be mentioned. Be done.
When the polymer is a (meth) acrylic polymer, (meth) acrylic acid or a derivative thereof, (meth) acrylic acid ester or a derivative thereof can be mentioned.
When the polymer is a (meth) acrylamide polymer, (meth) acrylamide or a derivative thereof can be mentioned.

When the polymer is polystyrene, styrene or a derivative thereof may be mentioned.
When the polymer is polysiloxane, a silane compound having a methoxy group or an ethoxy group can be mentioned.
When the polymer is a polyamide, examples thereof include at least one dicarboxylic acid component and a diamine component selected from a dicarboxylic acid and a derivative thereof.
When the polymer is polyester, at least one dicarboxylic acid component and a diol component selected from the dicarboxylic acid and its derivatives can be mentioned.

When the polymer is polyurethane, examples thereof include an isocyanate compound and a compound having a hydroxy group.
When the polymer is polycarbonate, bisphenol derivatives and phosgene or phosgene equivalents (eg, trichlorophosgene) or diphenyl carbonates can be mentioned.
When the polymer is polyurea, bisisocyanate derivatives and diamine components can be mentioned.
When the polymer is a maleimide polymer, the maleimide derivative alone or copolymerization with styrene may be mentioned.
In the case of a polymer into which a compound having an isocyanuric acid skeleton or a triazine skeleton is introduced, examples of the polymer have a compound having an isocyanuric acid skeleton or a triazine skeleton.

<< Polyimide-based polymer >>
Among the polymers contained in the liquid crystal alignment agent of the present invention, the polyimide precursor and the polyimide precursor are selected from the viewpoints of practicality as a liquid crystal alignment agent, mechanical strength of the coating film, and liquid crystal orientation. One or more polymers (hereinafter, also referred to as polyimide-based polymers) selected from the group consisting of polyimides that are imidized products are preferable.
The polyimide-based polymer can be produced by a known method. For example, polyamic acid, which is a polyimide precursor, is obtained by polymerizing (polycondensing) a tetracarboxylic acid component composed of a tetracarboxylic acid dianhydride or a derivative thereof and a diamine component, and this polyimide precursor is used. Polyimide can be obtained by imidization. Derivatives of the tetracarboxylic dianhydride include a tetracarboxylic dianhydride, a tetracarboxylic dianyl ester, or a tetracarboxylic dianhydride.

<<< Tetracarboxylic acid component >>>
Examples of the polyamic acid as a polyimide precursor include those obtained from a tetracarboxylic acid component containing an aromatic, acyclic aliphatic or alicyclic tetracarboxylic dianhydride. Here, the aromatic tetracarboxylic dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxy groups including at least one carboxy group bonded to the aromatic ring. The acyclic aliphatic tetracarboxylic dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxy groups bonded to a chain hydrocarbon structure. However, it does not have to be composed only of a chain hydrocarbon structure, and may have an alicyclic structure or an aromatic ring structure as a part thereof.

The alicyclic tetracarboxylic dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxy groups including at least one carboxy group bonded to the alicyclic structure. However, none of these four carboxy groups are bonded to the aromatic ring.
Further, it does not have to be composed only of an alicyclic structure, and may have a chain hydrocarbon structure or an aromatic ring structure as a part thereof.

The polyamic acid according to the present invention is preferably one obtained from a tetracarboxylic acid component containing a tetracarboxylic dianhydride represented by the following formula (2).

(X represents a structure selected from the following equations (x-1) to (x-13).)

(R ¹ to R ⁴ 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, and a fluorine atom. It represents a monovalent organic group or a phenyl group having 1 to 6 carbon atoms. R ⁵ and R ⁶ independently represent a hydrogen atom or a methyl group. J and k are integers of 0 or 1. , _{a 1} and _{a 2} are each independently a single bond, -O -, - CO -, -. COO-, a phenylene group, a sulfonyl group or an more _{a 2} an amide group, are different from each identical * 1 is a bond that binds to one acid anhydride group, and * 2 is a bond that binds to the other acid anhydride group.)

As a preferable specific example of the tetracarboxylic dianhydride represented by the above formula (2) or a derivative thereof, X is the above formulas (x-1) to (x-8) and (x-10) to (x). The one selected from -13) can be mentioned.

The above formula (x-1) is preferably selected from the group consisting of the following formulas (x1-1) to (x1-6).

(* 1 is a bond that binds to one acid anhydride group, and * 2 is a bond that binds to the other acid anhydride group.)

Preferred specific examples of the above formulas (x-12) and (x-13) include the following formulas (x-14) to (x-29). In addition, "*" in the formula represents a coupling position.

The amount of the tetracarboxylic dianhydride or its derivative represented by the above formula (2) is preferably 60 to 100 mol% based on 1 mol of the total tetracarboxylic acid component to be reacted with the diamine component, 80. It is more preferably ~ 100 mol%, still more preferably 90-100 mol%.

<<< Diamine component >>>
The diamine component used for producing the polyimide precursor is not particularly limited, but a diamine component containing at least one diamine selected from the diamines represented by the following formulas (3) and (3i) is preferable.

(Y ₃ represents a divalent organic group represented by the following formula (O). R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Y _3i is represented by the following formula (O'). Represents a divalent organic group.)

(Ar represents a divalent benzene ring, a biphenyl structure, or a naphthalene ring. The two Ars may be the same or different, and any hydrogen atom in the ring may be substituted with a monovalent substituent. .p is .Q ₃ is an integer of 0 or 1 _{_{- (CH 2) n - (}} . n is an integer of 2 to 18), or the _{_{- (CH 2) n - -CH}} 2 of - at least Represents a group in which a part is replaced with either -O-, -C (= O)-or -OC (= O)-. * Represents a bond.)

(Ar'represents a divalent benzene ring or a biphenyl structure. The two Ar's may be the same or different, and any hydrogen atom in the ring may be substituted with a monovalent substituent. p 'is an integer of 0 or 1 .Q _3' is - _(CH ₂₎ n - (. n is an integer of 2 to 18), or the - _(CH _{2) n} - of - -CH ₂ of Represents a group in which at least a part is replaced with either -O-, -C (= O)-or -OC (= O)-. * Represents a bond.)

Examples of the substituent of the ring include a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and a fluoroalkyl group having 1 to 10 carbon atoms. Examples thereof include a fluoroalkenyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, a carboxy group and a hydroxy group, an alkyloxycarbonyl group having 1 to 10 carbon atoms, a cyano group and a nitro group.

The divalent organic group represented by the above formula (O) is preferably a divalent organic group represented by the following formulas (o-1) to (o-16) from the viewpoint of enhancing the liquid crystal orientation.

("*" In the formula indicates the bond position.)

The divalent organic group represented by the above formula (O') is preferably a divalent organic group represented by the above formulas (o-7) to (o-16) from the viewpoint of enhancing the liquid crystal orientation.

Preferred specific examples of the diamine represented by the above formula (3i) include compounds represented by the following formulas (3i-1) to (3i-5).

The total ratio of the diamine represented by the formula (3) and the diamine represented by the formula (3i) is preferably 1 to 95 mol% with respect to 1 mol of the diamine component, and is preferably 1 to 90 mol%. More preferably, it is more preferably 5 to 90 mol%.

The polyimide-based polymer used in the present invention has a nitrogen-containing heterocycle (excluding the imide ring of the polyimide), a secondary amino group, and a third, from the viewpoint of increasing the voltage retention of the obtained liquid crystal alignment film. It may have at least one nitrogen-containing structure (hereinafter, also referred to as a nitrogen-containing structure) selected from the group consisting of a secondary amino group. The polyimide-based polymer having a nitrogen-containing structure can be obtained by using a monomer having a nitrogen-containing structure, for example, a diamine having a nitrogen-containing structure as at least a part of a raw material.

Examples of the nitrogen-containing heterocycle that the diamine having a nitrogen-containing structure may have include pyrrole, imidazole, pyrazole, triazole, pyridine, pyrimidine, pyridazine, pyrazine, indole, benzimidazole, purine, quinoline, and isoquinoline. Examples thereof include naphthylidine, quinoxalin, phthalazine, triazine, carbazole, aclysine, piperidine, piperazine, pyrrolidine, hexamethyleneimine and the like. Of these, pyridine, pyrimidine, pyrazine, piperidine, piperazine, quinoline, carbazole or acridine are preferable.

The secondary amino group and the tertiary amino group that the diamine having the nitrogen-containing structure may have are represented by, for example, the following formula (n).

In the above formula (n), R represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. "*" Represents a bond that binds to a hydrocarbon group.

Examples of the monovalent hydrocarbon group of R in the above formula (n) include an alkyl group such as a methyl group, an ethyl group and a propyl group; a cycloalkyl group such as a cyclohexyl group; and an aryl such as a phenyl group and a methylphenyl group. The group etc. can be mentioned. R is preferably a hydrogen atom or a methyl group.

Specific examples of the diamine having a nitrogen-containing structure include 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, and N-methyl-3,6-diaminocarbazole. , 1,4-Bis- (4-aminophenyl) -pyrimidine, 3,6-diaminoacridine, N-ethyl-3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, the following formula (Dp- Examples thereof include compounds represented by 1) to (Dp-9) and compounds represented by the following formulas (z-1) to (z-18).

The ratio of diamine having a nitrogen-containing structure is preferably 1 mol% or more, more preferably 2 mol% or more, based on the total amount of diamine used for synthesis, from the viewpoint of increasing the voltage retention rate of the liquid crystal display element. The usage ratio is preferably 90 mol% or less, more preferably 80 mol% or less.

The polyimide-based polymer used in the present invention may contain other diamines other than the diamines described above. Examples of other diamines are given below, but the present invention is not limited thereto.
A diamine having 6 to 30 carbon atoms having the group "-N (D)-(D represents a carbamate-based protecting group)" in the molecule; 4,4'-diaminoazobenzene and the following formula (d _T -1) to Diamines having a photo-oriented group such as diamine represented by (d _T -3); 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,3'- Diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminobenzophenone, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-Aminophenyl) benzene, 1,3-bis (4-aminophenyl) benzene, 1,4-bis (4-aminobenzyl) benzene, 2,4-diaminophenol, 3,5-diaminophenol, 3, 5-Diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol; 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, 3,5-diaminobenzoic acid and the following formula (3b-). 1) Diamines having a carboxy group such as the diamine compounds shown in (3b-4); 4- (2- (methylamino) ethyl) aniline, 4- (2-aminoethyl) aniline, 4,4'-diamino Diphenylmethane, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenyl ether, 4,4'-diaminobenzanilide, 4,4'-diaminoazobenzene, 1- (4-aminophenyl) -1,3,3- Trimethyl-1H-indane-5-amine, 1- (4-aminophenyl) -2,3-dihydro-1,3,3-trimethyl-1H-inden-6-amine; the following formulas (h-1) to ( Diamine having a urea bond such as a diamine represented by h-3); Diamine having an amide bond represented by the following formulas (h-4) to (h-6); 2- (2,4-diamino) methacrylate Phenoxy) Diamines having photopolymerizable groups such as ethyl and 2,4-diamino-N, N-diallylaniline at the ends; cholestanyloxy-3,5-diaminobenzene, cholestenyloxy-3,5-diaminobenzene, Cholestanyloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, cholestenyl 3,5-diaminobenzoate, lanostannyl 3,5-diaminobenzoate and 3,6-bis (4-aminobenzoyloki) B) Diamine having a steroid skeleton such as cholesterol; diamine represented by the following formulas (V-1) to (V-6); siloxane bond such as 1,3-bis (3-aminopropyl) -tetramethyldisiloxane Diamines such as diamines having an oxazoline structure such as the following formulas (Ox-1) to (Ox-2); formulas (Y-1) to (Y-167) described in International Publication No. 2018/1172339. Examples thereof include diamines in which two amino groups are bonded to a group represented by any of the above.

(In the formula ^{(3b-1), A} 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-, m1 and m2 independently represent an integer of 0 to 4, and m1 + m2 represent an integer of 1 to 4. Equation (3b-2). Medium, m3 and m4 each independently represent an integer of 1 to 5. In the formula (3b-3), A ² represents a linear or branched alkyl group having 1 to 5 carbon atoms, and m5 represents 1 to 5. . of an integer expression in (3b-4), ^{a 3} and ^{a 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- represents, m6 is an integer of 1-4).

(X ^v1 to X ^v4 and X ^p1 to X ^p2 are independently-(CH ₂ ) _a- (a is an integer of 1 to 15), -CONH-, -NHCO-, and -CON (CH). _{_{3) -, - NH -,}} - O -, - CH 2 O -, - CH 2 OCO -, - COO-, or -OCO- ^{represent, X v5} is _{-O -, - CH 2 O -} , - CH ₂ Represents OCO-, -COO-, or -OCO-. X _a is a single bond, -O-, _{-NH-, or -O- (CH 2} _{) m-} O- (m is an integer of 1 to 6). R ^v1 to R ^v4 and R ^1a to R ^1b independently represent an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkoxyalkyl group having 2 to 20 carbon atoms. Represents a group.)

A diamine having 6 to 30 carbon atoms having the above group "-N (D)-(D represents a carbamate-based protecting group)" in the molecule is represented by the following formulas (5-1) to (5-10). Examples include the represented compounds.

(Boc represents a tert-butoxycarbonyl group.)

<Ingredient (B)>
One aspect of the liquid crystal alignment agent of the present invention is characterized by containing the hydroxyalkylamide compound (B) represented by the following formula (1).

The alkyl group having 1 to 6 carbon atoms of R in the above formula (1) includes a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group and a tert-butyl group. , N-pentyl group, n-hexyl group, cyclopentyl group, cyclohexyl group and the like.

_{The monovalent organic group having 1 to 6 carbon atoms of R 1} and R ₂ in the above formula (1) includes an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, and 2 to 6 carbon atoms. Alkinyl group, or a hetero atom-containing group containing a group having a hetero atom between carbons of these groups, and a part or all of the hydrogen atoms of the above-mentioned alkyl group, alkenyl group, alkynyl group and hetero atom-containing group are substituted. Examples include groups substituted with groups.

Examples of the group having a hetero atom include a group having at least one selected from the group consisting of an oxygen atom, a nitrogen atom, a silicon atom, a phosphorus atom and a sulfur atom, and examples thereof include -O- and -NR- (R). Represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms), -CO-, -S-, -CO-, and a group combining these. Of these, —O— is preferable.

Examples of the substituent include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom; alkoxy group such as methoxy group, ethoxy group and propoxy group; alkoxycarbonyl group such as methoxycarbonyl group and ethoxycarbonyl group; methoxy. Alkoxycarbonyloxy groups such as carbonyloxy group and ethoxycarbonyloxy group; cyano group, nitro group, hydroxy group and the like can be mentioned.

From the viewpoint of enhancing the liquid crystal orientation, R ₁ in the above formula (1) is preferably a hydrogen atom or a methyl group, and R ₂ is preferably a hydrogen atom.

The divalent organic group having 1 to 30 carbon atoms of A in the above formula (1) includes, for example, a divalent hydrocarbon group and a divalent group having the above heteroatom between carbon and carbon of the hydrocarbon group. heteroatom-containing group, the divalent divalent organic group in which some or all of the hydrogen atoms substituted with substituents exemplified above R _1, R ₂ hydrocarbon groups and divalent heteroatom-containing groups having And so on.

Examples of the divalent hydrocarbon group include alkenes such as methane, ethane, propane, and butane; alkenes such as ethylene, propene, butene, and pentene; and alkynes such as ethine, propine, butine, and pentine having 1 to 1 carbon atoms. 30 chain hydrocarbons, cyclopropane, cyclobutane, cyclopentane, cyclohexane, norbornan, adamantan and other cycloalkanes, cyclopropene, cyclobutene, cyclopentene, cyclohexene, norbornene and other cycloalkenes, etc. Two hydrogen atoms are removed from hydrocarbons such as aromatic hydrocarbons having 6 to 30 carbon atoms such as hydrocarbons, benzene, toluene, xylene, mesitylene, naphthalene, methylnaphthalene, dimethylnaphthalene, anthracene and the like 2 Hydrocarbon groups of valence and the like can be mentioned.

As A in the above formula (1), a divalent hydrocarbon group having 1 to 30 carbon atoms is preferable, and a divalent chain hydrocarbon having 1 to 30 carbon atoms or an aromatic having 6 to 30 carbon atoms is more preferable. A divalent hydrocarbon group obtained by removing two hydrogen atoms from a group hydrocarbon is preferable.
The divalent chain hydrocarbon having 1 to 30 carbon atoms is preferably a divalent chain hydrocarbon having 2 to 30 carbon atoms, and more preferably a divalent chain hydrocarbon having 2 to 16 carbon atoms.

The hydroxyalkylamide compound represented by the above formula (1) is preferably any of the compounds represented by the following formulas (b-1) to (b-3).

The preferable content of the hydroxyalkylamide compound represented by the above formula (1) in the liquid crystal alignment agent of the present invention is preferably 0.1 to 50 parts by mass with respect to 100 parts by mass of the component (A), 0.1. ~ 30 parts by mass is more preferable.

<(B') component>
Another aspect of the liquid crystal alignment agent of the present invention is characterized by containing a hydroxyalkylamide compound (B') represented by the following formula (1').

The monovalent organic group having 1 to 6 carbon atoms and R _{2 ''} R ₁ in the formula (1) _', can be mentioned structure illustrated in R ₁ and R ₂ in the formula (1), It is the same as _{R 1} and R ₂ , respectively, including preferable specific examples.

Divalent organic groups, for example, a divalent hydrocarbon group having 1 to 10 carbon atoms having 1 to 10 carbon atoms 'L ₁ in the formula _(1)', the carbon of the hydrocarbon group - above between carbon A divalent heteroatom-containing group including a group having a heteroatom, a part or all of the hydrogen atoms contained in the divalent hydrocarbon group and the divalent heteroatom-containing group are R ₁ , R in the above formula (1). Examples thereof include a divalent organic group substituted with the substituent exemplified in _2. Specific examples of the divalent hydrocarbon group include the hydrocarbon group exemplified by A in the above formula (1).
The 'L ₁ in the formula _(1)' is preferably a divalent hydrocarbon group having 1 to 10 carbon atoms, more preferably a divalent chain hydrocarbon of 1 to 10 carbon atoms, or C 6 -C A divalent hydrocarbon group obtained by removing 2 hydrogen atoms from 10 aromatic hydrocarbons is preferable.
The divalent chain hydrocarbon having 1 to 10 carbon atoms is preferably a divalent chain hydrocarbon having 2 to 10 carbon atoms, and more preferably a divalent chain hydrocarbon having 2 to 8 carbon atoms.

For n in the above formula (1'), an integer of 1 to 20 is more preferable, and an integer of 2 to 20 is further preferable.

The hydroxyalkylamide compound represented by the above formula (1') is preferably any of the compounds represented by the following formulas (b'-1) to (b'-5).

The preferable content of the hydroxyalkylamide compound represented by the above formula (1') in the liquid crystal alignment agent of the present invention is preferably 0.1 to 50 parts by mass with respect to 100 parts by mass of the component (A'), and is 0. .1 to 30 parts by mass is more preferable.

<Manufacturing method of polyamic acid>
The polyimide precursor polyamic acid used in the present invention can be produced by the following method. Specifically, the tetracarboxylic acid component and the diamine component are reacted in the presence of an organic solvent at −20 to 150 ° C., preferably 0 to 50 ° C. for 30 minutes to 24 hours, preferably 1 to 12 hours (. It can be synthesized by subjecting it to a polycondensation reaction).
Specific examples of the organic solvent used in the above reaction include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, and the like. Examples thereof include 1,3-dimethyl-2-imidazolidinone. When the polymer has high solvent solubility, it is represented by methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or the following formulas [D-1] to [D-3]. Can be used as a solvent. These may be used by mixing two or more kinds.

(In the formula [D-1], D ¹ represents an alkyl group having 1 to 3 carbon atoms, and in the formula [D-2], D ² represents an alkyl group having 1 to 3 carbon atoms, and the formula [D-3]. ], D ³ represents an alkyl group having 1 to 4 carbon atoms.)

The reaction can be carried out at any concentration, but is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The initial reaction can be carried out at a high concentration and then the solvent can be added. In the reaction, the ratio of the total number of moles of the diamine component to the total number of moles of the tetracarboxylic acid component is preferably 0.8 to 1.2. Similar to a normal polycondensation reaction, the closer the molar ratio is to 1.0, the larger the molecular weight of the polyamic acid produced.

The polyamic acid obtained in the above reaction can be recovered by precipitating the polyamic acid by injecting the reaction solution into a poor solvent while stirring well. Further, the purified polyamic acid powder can be obtained by performing precipitation several times, washing with a poor solvent, and then drying at room temperature or by heating. The antisolvent is not particularly limited, and examples thereof include water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

When the polyimide precursor is a polyamic acid ester, (1) a method for esterifying a polyamic acid obtained from tetracarboxylic acid dianhydride and diamine. (2) A method based on a reaction between a tetracarboxylic dianester dichloride and a diamine. (3) It can be produced by a known method such as a method of polycondensing a tetracarboxylic diandiester and a diamine.

The polyimide precursor may be a terminal-modified polymer obtained by using an appropriate terminal encapsulant together with the tetracarboxylic acid derivative and diamine as described above when producing the polyimide precursor.
Examples of the terminal modifier include acid anhydrides such as acetic anhydride, maleic anhydride, nagic anhydride, phthalic anhydride, itaconic anhydride, cyclohexanedicarboxylic acid anhydride, 3-hydroxyphthalic anhydride, and trimetic acid anhydride. Di-tert-butyl dicarbonate; aniline, 2-aminophenol, 3-aminophenol, 4-aminosalicylic acid, 5-aminosalicylic acid, 6-aminosalicylic acid, 2-aminobenzoic acid, 3-aminobenzoic acid, 4-amino Examples thereof include monoamine compounds such as benzoic acid; monoisocyanate compounds such as ethyl isocyanate, phenyl isocyanate and naphthyl isocyanate.
The ratio of the terminal modifier to be used is preferably 40 mol parts or less, more preferably 30 mol parts or less, based on 100 mol parts in total of the diamine component used.

<Polyimide manufacturing method>
The polyimide used in the present invention can be produced by imidizing a polyamic acid or a polyamic acid ester, which is a polyimide precursor, by a known method.
In polyimide, the ring closure rate (also referred to as imidization rate) of the functional group of the polyamic acid or the polyamic acid ester does not necessarily have to be 100%, and can be arbitrarily adjusted according to the intended use and purpose.

As a method for imidizing the polyamic acid or the polyamic acid ester to obtain a polyimide, thermal imidization in which the solution of the polyamic acid or the polyamic acid ester is heated as it is, or a catalyst is added to the solution of the polyamic acid or the polyamic acid ester. Catalytic imidization can be mentioned. The temperature for thermal imidization is 100 to 400 ° C., preferably 120 to 250 ° C., and it is preferable to remove the water produced by the imidization reaction from the outside of the system.

Catalyst imidization can be carried out by adding a basic catalyst and an acid anhydride to a solution of the polymer and stirring at −20 to 250 ° C., preferably 0 to 180 ° C. The amount of the basic catalyst is 0.5 to 30 mol times, preferably 2 to 20 mol times the amount of the amic acid group or the amic acid ester group, and the amount of the acid anhydride is 1 to 1 to 1 to the amic acid group or the amic acid ester group. It is 50 mol times, preferably 3 to 30 mol times. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, and tributylamine trioctylamine. Among them, pyridine is preferable because it has an appropriate basicity for advancing the reaction. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride and the like, and among them, acetic anhydride is preferable because it facilitates purification after the reaction is completed. The imidization rate by catalytic imidization can be controlled by adjusting the amount of catalyst, the reaction temperature, and the reaction time.

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

<Solution viscosity / molecular weight of polymer>
The polyamic acid, polyamic acid ester and polyimide used in the present invention preferably have a solution viscosity of, for example, 10 to 1000 mPa · s when the solution is made into a solution having a concentration of 10 to 15% by mass, from the viewpoint of workability. , Not particularly limited. The solution viscosity (mPa · s) of the polymer is a polymer having a concentration of 10 to 15% by mass prepared by using a good solvent of the polymer (for example, γ-butyrolactone, N-methyl-2-pyrrolidone, etc.). The values of the solution were measured at 25 ° C. using an E-type rotational viscometer.

The polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) of the polyamic acid, polyamic acid ester and polyimide is preferably 1,000 to 500,000, more preferably 2,000. ~ 500,000. The molecular weight distribution (Mw / Mn) represented by the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) measured by GPC is preferably 15 or less, more preferably 10 or less. Within such a molecular weight range, good liquid crystal orientation of the liquid crystal display element can be ensured.

<Preferable embodiment of liquid crystal alignment agent>
As a preferred embodiment of the liquid crystal aligning agent of the present invention, for example, the hydroxyalkylamide compound of the above formula (1) or (1') is contained in a solution in which a polymer having the ability to orient the liquid crystal is dissolved in a solvent. Examples include the added form.
The content (concentration) of the polymer contained in the liquid crystal alignment agent of the present invention can be appropriately changed by setting the thickness of the coating film to be formed, but it is a point that a uniform and defect-free coating film is formed. 1% by mass or more is preferable, and 10% by mass or less is preferable from the viewpoint of storage stability of the solution.
The content of the hydroxyalkylamide compound of the above formula (1) or (1') is the content of the polymer contained in the liquid crystal alignment agent and the hydroxyalkylamide compound of the above formula (1) or (1'). It is preferably 1 to 15% by mass, more preferably 2 to 10% by mass, and particularly preferably 2 to 8% by mass with respect to the total of.

The solvent contained in the liquid crystal alignment agent is not particularly limited as long as the polymer component is uniformly dissolved. Specific examples thereof include N, N-dimethylformamide, N, N-dimethylacetamide, N, N-dimethyllactamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylsulfoxide, and γ-butyrolactone. , Γ-Valerolactone, 1,3-dimethyl-2-imidazolidinone, methylethylketone, cyclohexanone, cyclopentanone, 3-methoxy-N, N-dimethylpropanamide, 3-butoxy-N, N-dimethylpropanamide, N- (n-propyl) -2-pyrrolidone, N-isopropyl-2-pyrrolidone, N- (n-butyl) -2-pyrrolidone, N- (tert-butyl) -2-pyrrolidone, N- (n-pentyl) ) -2-Pyrrolidone, N-methoxypropyl-2-pyrrolidone, N-ethoxyethyl-2-pyrrolidone, N-methoxybutyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone (collectively, "good solvent") Also known as). Of these, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N, N-dimethylpropanamide, 3-butoxy-N, N-dimethylpropanamide or γ-butyrolactone are preferable. The content of the good solvent 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 alignment agent.

The solvent contained in the liquid crystal alignment agent is a mixed solvent in which a solvent (also referred to as a poor solvent) that improves the coatability when the liquid crystal alignment agent is applied and the surface smoothness of the coating film is used in addition to the above solvent. Is preferred. Specific examples of the solvent to be used in combination are described below, but the present invention is not limited thereto.

For example, diisopropyl ether, diisobutyl ether, diisobutylcarbinol (2,6-dimethyl-4-heptanol), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-butoxyetan, 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, propylene glycol diacetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monobutyl ether ace Tart, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2- (2-ethoxyethoxy) ethyl acetate, diethylene glycol acetate, propylene glycol diacetate, n-butyl acetate, propylene glycol monoethyl ether acetate, 3- Methyl methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, n-butyl lactate, isoamyl lactate, diethylene glycol monoethyl ether, diisobutyl ketone (2) , 6-Dimethyl-4-heptanone) and the like. The content 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 total amount of the solvent contained in the liquid crystal alignment agent. The type and content of the poor solvent are appropriately selected according to the liquid crystal alignment agent coating device, coating conditions, coating environment, and the like.

Among them, diisobutylcarbinol, propylene glycol monobutyl ether, propylene glycol diacetate, diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monobutyl ether, ethylene. Glycol monobutyl ether acetate or diisobutyl ketone is preferred.

Preferred solvent combinations of good and poor solvents 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, 4-hydroxy-4-methyl-2-pentanone and diethylene glycol diethyl Ether, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol, monobutyl ether and diisobutylketone, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol, monobutyl ether and diisopropyl ether, N-methyl-2-pyrrolidone. Gamma-butylolactone and propylene glycol monobutyl ether and diisobutylcarbinol, N-methyl-2-pyrrolidone and γ-butyrolactone and dipropylene glycol dimethyl ether, N-methyl-2-pyrrolidone and propylene glycol monobutyl ether and dipropylene glycol dimethyl ether, etc. be able to.

The liquid crystal alignment agent of the present invention may additionally contain a component other than the polymer component and the solvent (hereinafter, also referred to as an additive component). Such additive components include an adhesion aid for enhancing the adhesion between the liquid crystal alignment film and the substrate and the adhesion between the liquid crystal alignment film and the sealing material, and a compound for increasing the strength of the liquid crystal alignment film (hereinafter,). (Also referred to as a crosslinkable compound), a dielectric for adjusting the dielectric constant and electrical resistance of the liquid crystal alignment film, a conductive substance, and the like can be mentioned.

The crosslinkable compound includes, for example, an oxylanyl group, an oxetanyl group, a protected isocyanate group, a protected isothiocyanate group, and an oxazoline ring structure from the viewpoint of exhibiting good resistance to AC afterimages and improving film strength. A compound having at least one group selected from the group consisting of a group, a group containing a merdrum acid structure and a cyclocarbonate group, a hydroxyalkylamide compound other than the compounds represented by the above formulas (1) and (1'), Alternatively, a compound selected from the compounds represented by the following formula (e) can be mentioned.

(A is an integer of .m 1-6 representing the (m + n) valent organic group having an aromatic ring, n represents 0 to 4 representing an integer _.R e, is _{R f,} each independently, hydrogen Represents an atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkynyl group having 2 to 6 carbon atoms. The aromatic ring of A may be substituted with a monovalent group. Specific examples of the valent group include monovalent organic groups represented by Ar substituents of the above formula (O) (excluding alkoxy groups having 1 to 10 carbon atoms).

Specific examples of the compound having an oxylanyl group include the compound described in paragraph [0037] of JP-A No. 10-338880 and the compound having a triazine ring as a skeleton described in International Publication No. 2017/170483. Examples thereof include compounds having more than one oxylanyl group. Of these, N, N, N', N'-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N', N'-tetra Nitrogen atoms such as glycidyl-4, 4'-diaminodiphenylmethane, N, N, N', N'-tetraglycidyl-p-phenylenediamine, compounds represented by the following formulas (r-1) to (r-3). It may be a compound containing.

Specific examples of the compound having an oxetanyl group include the compounds having two or more oxetanyl groups described in paragraphs [0170] to [0175] of International Publication No. 2011/132751.

Specific examples of the compound having a protected isocyanate group include the compounds having two or more protected isocyanate groups described in paragraphs [0046] to [0047] of Japanese Patent Application Laid-Open No. 2014-224978, International Publication No. 2015/141598. The compounds having three or more protected isocyanate groups described in paragraphs [0119] to [0120] of the above are mentioned, and the compounds represented by the following formulas (bi-1) to (bi-3) may be used. ..

Specific examples of the compound having a protected isothiocyanate group include the compounds having two or more protected isothiocyanate groups described in Japanese Patent Application Laid-Open No. 2016-2000798.

Specific examples of the compound having a group containing an oxazoline ring structure include compounds containing two or more oxazoline structures described in paragraph [0115] of Japanese Patent Application Laid-Open No. 2007-286597.

Specific examples of the compound having a group containing a Meldrum's acid structure include the compound having two or more Meldrum's acid structures described in International Publication No. 2012/091088.

Specific examples of the compound having a cyclocarbonate group include the compound described in International Publication No. 2011/155577.

Specific examples of hydroxyalkylamide compounds other than the compounds represented by the above formulas (1) and (1') include International Publication No. 2015/072554 and paragraph [0058] of Japanese Patent Application Laid-Open No. 2016-118753. , The compound described in Japanese Patent Application Laid-Open No. 2016-200798, the compound described in International Publication No. 2019/142927, and the like, which are represented by the following formulas (hd-1) to (hd-8). The compound may be a compound represented by the following formulas (hd1-1) to (hd1-4).

Examples of the (m + n) -valent organic group having an aromatic ring in A of the above formula (e) include an (m + n) -valent aromatic hydrocarbon group having 6 to 30 carbon atoms and an aromatic hydrocarbon group having 6 to 30 carbon atoms. Examples thereof include a (m + n) valent organic group bonded directly or via a linking group, and a (m + n) valent group having an aromatic heterocycle. Examples of the aromatic hydrocarbon include benzene and naphthalene. Examples of the aromatic heterocycle include a pyrrole ring, an imidazole ring, a pyrazole ring, a pyridine ring, a pyrimidine ring, a quinoline ring, an isoquinoline ring, a carbazole ring, a pyridazine ring, a pyrazine ring, a benzimidazole ring, an indole ring, a quinoxaline ring, and an acridin ring. And so on. The linking group includes an alkylene group having 1 to 10 carbon atoms, -NR- (R is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms), an alkylene group having a fluorine atom and 1 to 10 carbon atoms, or the above-mentioned alkylene group. Examples thereof include a group obtained by removing one hydrogen atom from the group, a divalent or trivalent cyclohexane ring, and the like. Any hydrogen atom of the alkylene group may be substituted with an organic group such as a fluorine atom or a trifluoromethyl group. Specific examples include the compounds described in International Publication No. 2010/074269 and the compounds represented by the following formulas (e-1) to (e-10).

The above compound is an example of a crosslinkable compound, and is not limited thereto. For example, components other than the above disclosed in International Publication No. 2015/060357 on pages 53 [0105] to 55 [0116] can be mentioned. Further, two or more kinds of crosslinkable compounds may be combined.

The content of the crosslinkable compound in the liquid crystal aligning agent of the present invention is preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the polymer component contained in the liquid crystal aligning agent, and the crosslinking reaction proceeds. In addition, from the viewpoint of exhibiting good resistance to AC afterimages, it is more preferably 1 to 15 parts by mass.

Examples of the adhesion aid include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, and 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 Nonylacetate, 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 Silane cups such as silane, tris- (trimethoxysilylpropyl) isocyanurate, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isoxapropyltriethoxysilane, etc. Ring agent can be mentioned. When a silane coupling agent is used, it should be 0.1 to 30 parts by mass with respect to 100 parts by mass of the polymer component contained in the liquid crystal alignment agent from the viewpoint of exhibiting good resistance to AC afterimage. It is preferable, more preferably 0.1 to 20 parts by mass.

(Liquid crystal alignment film)
The liquid crystal alignment film of the present invention is formed by using the liquid crystal alignment agent of the present invention.
Preferred embodiments of the method for producing a liquid crystal alignment film of the present invention include, for example, a step of applying the above liquid crystal alignment agent to a substrate (step (1)) and a step of firing the applied liquid crystal alignment agent (step (2)). In some cases, a method for producing a liquid crystal alignment film including a step (step (3)) of aligning the film obtained in the step (2) can be mentioned.

<Process (1)>
The substrate to which the liquid crystal alignment 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, a plastic substrate such as an acrylic substrate or a polycarbonate substrate, or the like can also be used. 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 reflective liquid crystal display element, an opaque object such as a silicon wafer can be used if only one side of the substrate is used, and a material that reflects light such as aluminum can also be used for the electrode in this case.

Examples of the method of applying the liquid crystal alignment agent to the substrate to form a film include screen printing, offset printing, flexographic printing, inkjet method, spray method and the like. Among them, the coating method by the inkjet method and the film forming method can be preferably used.

<Process (2)>
The step (2) is a step of firing the liquid crystal alignment agent applied on the substrate to form a film. After applying the liquid crystal alignment agent on the substrate, the solvent is evaporated by a heating means such as a hot plate, a heat circulation type oven or an IR (infrared) type oven, or the heat of the amic acid or the amic acid ester in the polymer is generated. It can be imidized. The drying and firing steps after applying the liquid crystal alignment agent of the present invention can be performed at any temperature and time, and may be performed a plurality of times. The temperature at which the solvent of the liquid crystal alignment agent is evaporated can be, for example, 40 to 180 ° C. From the viewpoint of shortening the process, it may be carried out at 40 to 150 ° C. The firing time is not particularly limited, and examples thereof include 1 to 10 minutes or 1 to 5 minutes. In the case of thermal imidization of the amic acid or the amic acid ester in the polymer, after the step of evaporating the organic solvent, a step of firing in a temperature range of, for example, 150 to 300 ° C. or 150 to 250 ° C. can be performed. .. The firing time is not particularly limited, and examples thereof include a firing time of 5 to 40 minutes or 5 to 30 minutes.
If the film-like material after firing is too thin, the reliability of the liquid crystal display element may decrease, so 5 to 300 nm is preferable, and 10 to 200 nm is more preferable.

<Process (3)>
The step (3) is, in some cases, a step of orienting the film obtained in the step (2). That is, in a vertically oriented liquid crystal display element such as a VA method or a PSA mode, the formed coating film can be used as it is as a liquid crystal alignment film, but the coating film may be subjected to an alignment ability imparting treatment. As a method for aligning the liquid crystal alignment film, a rubbing treatment method may be used, but a photoalignment treatment method is preferable. As a photo-alignment treatment method, the surface of the film-like material is irradiated with radiation deflected in a certain direction, and in some cases, heat treatment is performed at a temperature of 150 to 250 ° C. to achieve liquid crystal orientation (liquid crystal alignment). There is a method of giving (also called Noh). As the radiation, ultraviolet rays having a wavelength of 100 to 800 nm or visible light can be used. Among them, ultraviolet rays having a wavelength of preferably 100 to 400 nm, more preferably 200 to 400 nm.

The irradiation amount of the above radiation is preferably ^{1 to 10,000 mJ / cm 2.} Of these, 100 to 5,000 mJ / cm ² is preferable. Further, when irradiating with radiation, in order to improve the liquid crystal orientation, the substrate having the film-like substance may be irradiated while being heated at 50 to 250 ° C. The liquid crystal alignment film thus produced can stably orient liquid crystal molecules in a certain direction.
Further, by the above method, the liquid crystal alignment film irradiated with polarized radiation can be contact-treated with water or a solvent, or the liquid crystal alignment film irradiated with radiation can be heat-treated.

The solvent used for the contact treatment is not particularly limited as long as it is a solvent that dissolves the decomposition product generated from the film-like substance by irradiation with radiation. 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, cyclohexyl acetate and the like. Of these, water, 2-propanol, 1-methoxy-2-propanol or ethyl lactate are preferable from the viewpoint of versatility and solvent safety. More preferred are water, 1-methoxy-2-propanol or ethyl lactate. The solvent may be used alone or in combination of two or more.

Examples of the above contact treatment include immersion treatment and spray treatment (also referred to as spray treatment). The treatment time in these treatments is preferably 10 seconds to 1 hour from the viewpoint of efficiently dissolving the decomposition products generated from the film-like material by irradiation with radiation. Above all, it is preferable to carry out the immersion treatment for 1 to 30 minutes. Further, the solvent at the time of the contact treatment may be heated at room temperature, but is preferably 10 to 80 ° C. Above all, 20 to 50 ° C. is preferable. In addition, from the viewpoint of the solubility of the decomposition product, ultrasonic treatment or the like may be performed as necessary.

After the above contact treatment, it is preferable to perform rinsing (also referred to as rinsing) or firing with a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone, or methyl ethyl ketone. At that time, either rinsing or firing may be performed, or both may be performed. The firing temperature is preferably 150 to 300 ° C. Above all, 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.
The heat treatment for the coating film irradiated with the above radiation is more preferably at 50 to 300 ° C. for 1 to 30 minutes, and even more preferably at 120 to 250 ° C. for 1 to 30 minutes.

(Liquid crystal display element)
The liquid crystal display element of the present invention has the liquid crystal alignment film of the present invention.
The liquid crystal alignment film of the present invention is suitable as a liquid crystal alignment film for a transverse electric field type liquid crystal display element such as an IPS method or an FFS method from the viewpoint of obtaining high liquid crystal alignment, and is particularly suitable for an FFS type liquid crystal display element. It is useful as a liquid crystal alignment film.
The liquid crystal display element is manufactured by obtaining a substrate with a liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention, producing a liquid crystal cell by a known method, and arranging the liquid crystal in the liquid crystal cell. Can be done. Specifically, the following two methods can be mentioned. In the first method, first, two substrates are arranged facing each other through a gap (cell gap) so that the liquid crystal alignment films face each other. Next, the peripheral portions of the two substrates are bonded together using a sealant, and the liquid crystal composition is injected and filled into the surface of the substrate and the cell gap partitioned by the sealant to contact the film surface, and then the injection holes are sealed. Stop.

The second method is a method called the ODF (One Drop Fill) method. For example, an ultraviolet light-curable sealant is applied to a predetermined place on one of the two substrates on which the liquid crystal alignment film is formed, and the liquid crystal composition is further applied to a predetermined number of places on the liquid crystal alignment film surface. Is dropped. Then, the other substrate is bonded so that the liquid crystal alignment film faces each other, and the liquid crystal composition is spread over the entire surface of the substrate and brought into contact with the film surface. Next, the entire surface of the substrate is irradiated with ultraviolet light to cure the sealant. Regardless of which method is used, it is desirable to remove the flow orientation during liquid crystal filling by further heating the liquid crystal composition used to a temperature at which an isotropic phase is obtained and then slowly cooling the liquid crystal composition to room temperature.
When the coating film is subjected to the rubbing treatment, the two substrates are arranged so as to face each other so that the rubbing directions of the coating films are opposite to each other at a predetermined angle, for example, orthogonal or antiparallel. Similarly, when the photo-alignment treatment is performed, the orientation directions are arranged so as to face each other at a predetermined angle, for example, orthogonal or antiparallel.
As the sealing agent, for example, an epoxy resin containing a curing agent and aluminum oxide spheres as a spacer can be used. Examples of the liquid crystal include a nematic liquid crystal and a smectic liquid crystal, and among them, the nematic liquid crystal is preferable.

As the liquid crystal material, either a positive type liquid crystal material or a negative type liquid crystal material may be used, but a negative type liquid crystal material is preferable. Next, the 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. Examples of the polarizing plate include a polarizing plate in which a polarizing film called "H film" in which polyvinyl alcohol is stretch-oriented and iodine is absorbed sandwiched between a cellulose acetate protective film or a polarizing plate made of the H film itself. ..

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 measurement method of each characteristic in the following are as follows. Further, "Boc" represents a tert-butoxycarbonyl group.

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

(Diamine)
DA-1 to DA-6: Compounds represented by the following formulas (DA-1) to (DA-6), respectively.

(Tetracarboxylic dianhydride)
DAH-1 to DAH-2: Compounds represented by the following formulas (DAH-1) to (DAH-2), respectively.

(Crosslinking agent)
AD-1: Compound represented by the following formula (AD-1) AD-2: Compound represented by the following formula (AD-2). The compound was synthesized by the synthetic method described in Japanese Patent Publication No. 2018-537481 (paragraphs [0079] to [0080], FIG. 5).
AD-3: A compound represented by the following formula (AD-3).

[viscosity]
The viscosity of the polyamic acid solution is measured using an E-type viscometer (TVE-22H, manufactured by Toki Sangyo Co., Ltd.) at a sample volume of 1.1 mL, a cone rotor TE-1 (1 ° 34', R24), and a temperature of 25 ° C. did.

[Synthesis of monomer]
The method for synthesizing AD-3, which is a novel compound, will be described in detail below.

The product described in Synthesis Example 1 below ^{was identified by 1} H-NMR analysis (analytical conditions are as follows).
Equipment: BRUKER ADVANCE III-500MHz
Measuring solvent: Deuterated dimethyl sulfoxide (DMSO-d ₆ )
Reference substance: Tetramethylsilane (TMS) (δ0.0 ppm for ¹ H)

(Synthesis Example 1 Synthesis of AD-3)
AD-3 was synthesized according to the following scheme.

<Synthesis of AD-3-1>
To tetraethylene glycol (10.0 g, 51.5 mmol), succinic anhydride (13.0 g, 130 mmol), dichloromethane (60 g), and 4-dimethylaminopyridine (3.14 g, 25.7 mmol) were added. The mixture was heated under reflux at 50 ° C. for 6 hours. After completion of the reaction, the mixture was cooled to room temperature of 25 ° C., washed twice with 2N hydrochloric acid (60 g), concentrated and dried to obtain AD-3-1 (yield: 15.6 g, 39.6 mmol, yield). Rate 77%).
^{1 1} H-NMR (500MHz) in DMSO-d ₆ : 12.20 (br, 2H), 4.12 (t, 4H), 3.59 (t, 4H), 3.53 (s, 8H), 2 .51 (t, 4H), 2.47 (t, 4H).

<Synthesis of AD-3-2>
Dichloromethane (94 g), oxalyl chloride (10.4 g, 81.9 mmol), and DMF (0.16 g) were added to AD-3-1 (15.6 g, 39.6 mmol), and the temperature at room temperature was 25 ° C. for 5 hours. Stirred. After completion of the reaction, the solution was concentrated to obtain a crude product of AD-3-2 (yield: 18 g). The obtained crude product of AD-3-2 was used as it was in the next step.

<Synthesis of AD-3>
Dichloromethane (86 g) and triethylamine (8.82 g, 87.2 mmol) were added to bis (2-((trimethylsilyl) oxy) ethyl) amine (20.8 g, 83.3 mmol) and cooled to 0 ° C. in an ice bath. Then, the crude product (18 g) of AD-3-2 diluted with dichloromethane (34 g) was added dropwise, and after completion of the addition, the mixture was stirred at room temperature of 25 ° C. for 17 hours. The precipitated triethylamine hydrochloride was removed by filtration, and when water was added, it was emulsified and the liquid separation property was significantly deteriorated. When methanol was added to the crude product, the target product was dissolved and salts were precipitated, so the mixture was filtered and concentrated. This was repeated 3 times and the salt was removed by filtration. Methanol (108 g) was added to the crude product, acetic acid (0.030 g) was added, and the mixture was heated and stirred at 80 ° C. for 2 hours. After confirming the elimination of the trimethylsilyl group, the reaction solution was concentrated. Methanol was added and azeotrope was repeated to remove acetic acid, acetonitrile and special Shirasagi activated carbon were added, and the mixture was heated and stirred at 80 ° C., then filtered and concentrated. This was repeated twice and dried to obtain AD-3 (yield: 13.1 g, 23.0 mmol, two-step yield 58%).
^{1 1} H-NMR (500MHz) in DMSO-d ₆ : 4.98 (br, 4H), 4.12 (t, 4H), 3.59 (t, 4H), 3.57-3.43 (m, 12H), 3.41-3.38 (m, 8H), 3.32 (t, 4H), 2.69-2.61 (m, 4H), 2.53-2.49 (m, 4H) ..

[Synthesis of polymer]
(Manufacturing Example 1)
DA-1 (1.08 g, 10 mmol), DA-2 (3.66 g, 15 mmol), DA-3 (4.81 g, 15 mmol) and DA- in a 200 mL four-necked flask with a stirrer and a nitrogen inlet tube. After adding 4 (3.98 g, 10 mmol), NMP (132 g) was added, and the mixture was stirred and dissolved while feeding nitrogen. DAH-1 (10.54 g, 47 mmol) was added while stirring this diamine solution, NMP (40.3 g) was added, and the mixture was further stirred at 40 ° C. for 12 hours to obtain a polyamic acid having a solid content concentration of 12% by mass. A solution (PAA-1) was obtained. The viscosity of this polyamic acid solution was 430 mPa · s.

(Manufacturing Example 2)
Weigh DA-5 (3.99 g, 20 mmol) and DA-6 (1.49 g, 5.0 mmol) into a 100 mL four-necked flask with a stirrer and a nitrogen inlet tube, then add 49 g of NMP. Then, nitrogen was sent and stirred to dissolve. DAH-2 (4.71 g, 24 mmol) was added while stirring this diamine solution, NMP was further added so that the solid content concentration became 10% by mass, and the mixture was stirred at room temperature for 20 hours to obtain a polyamic acid solution (PAA-). 2) (Viscosity: 150 mPa · s) was obtained.

[Preparation of sample solution]
(Comparative Example 1)
The polyamic acid solution (PAA-1) (1.33 g) obtained in Production Example 1 was weighed in a 50 mL Erlenmeyer flask containing a stirrer, and the polyamic acid solution (PAA-2) obtained in Production Example 2 was weighed. (2.40 g) was added. Further, NMP (0.27 g), GBL (2.20 g), BCS (3.00 g), and a 10% NMP solution (0.80 g) of AD-1 were added, and the mixture was stirred overnight with a magnetic stirrer to form a liquid crystal alignment agent (liquid crystal alignment agent). AL-1) was obtained.

(Examples 1 and 2)
Liquid crystal alignment agents (AL-2) to (AL-3) can be obtained by performing the same operation as in Comparative Example 1 except that AD-2 to AD-3 are used instead of AD-1. rice field.

(Comparative Example 2)
Add 10% NMP solution (1.20 g) of AD-1 to a 50 mL Erlenmeyer flask containing a stirrer, add NMP (2.80 g), GBL (3.00 g) and BCS (3.00 g), and add Magne. The solution (Sol-1) was obtained by stirring overnight with a tick stirrer.

(Examples 3 to 4)
Solutions (Sol-2) to (Sol-3) were obtained by performing the same operation as in Comparative Example 2 except that AD-2 to AD-3 were used instead of AD-1.

[Evaluation of liquid crystal alignment agent]
The afterimage evaluation and rubbing resistance test described below were performed on a liquid crystal alignment film formed by using the liquid crystal alignment agents of Comparative Example 1 and Examples 1 and 2, respectively, and a liquid crystal element having the liquid crystal alignment film.

<Manufacturing of liquid crystal cell>
A liquid crystal cell having a configuration of an FFS mode liquid crystal display element was manufactured.
First, a substrate with electrodes was prepared. As the substrate, a glass substrate having a rectangular shape of 30 mm × 35 mm and a thickness of 0.7 mm was used. An ITO electrode having a solid pattern forming a counter electrode as a first layer is formed on the substrate, and a film is formed on the counter electrode of the first layer as a second layer by a CVD method. A SiN (silicon nitride) film was formed. As the SiN film of the second layer, a film having a film thickness of 500 nm that functions as an interlayer insulating film was used. On the SiN film of the second layer, a comb-shaped pixel electrode formed by patterning an ITO film as the third layer is arranged, and two pixels of the first pixel and the second pixel are formed. Was there. The size of each pixel was 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 were electrically insulated by the action of the SiN film of the second layer.

The pixel electrode of the third layer has a comb-teeth shape in which a plurality of electrode elements having a width of 3 μm in which the central portion is bent at an internal angle of 160 ° are arranged in parallel with an interval of 6 μm. The pixel had a first region and a second region with a line connecting the bent portions of the plurality of electrode elements as a boundary.

Next, the liquid crystal alignment agents (AL-1) to (AL-3) obtained in Comparative Example 1 and Examples 1 and 2 were filtered through a filter having a pore size of 1.0 μm, and then the substrate with the electrode was prepared. It was applied by spin coating to a glass substrate having a columnar spacer having a height of 4 μm and having an ITO film formed on the back surface. After drying on a hot plate at 80 ° C. for 2 minutes, baking was performed at 230 ° C. for 30 minutes using an IR oven to form a coating film having a thickness of 100 nm. The surface of the coating film was irradiated with polarized ultraviolet rays at 300 mJ / cm ² to perform an orientation treatment. Firing was performed again at 230 ° C. for 30 minutes using an IR oven to obtain a substrate with a liquid crystal alignment film. A set of the above two substrates is printed with a sealant (XN-1500T manufactured by Mitsui Chemicals, Inc.) around it, leaving the liquid crystal injection port, and the other substrate is oriented with the liquid crystal alignment film surface facing 0. After laminating at °, the sealant was cured to prepare an empty cell. A liquid crystal MLC-3019 (manufactured by Merck & Co., Inc.) was injected into this empty cell by a vacuum injection method, and the injection port was sealed to obtain an FFS-driven liquid crystal cell.
The FFS-driven liquid crystal cell obtained as described above was heated at 110 ° C. for 1 hour, left overnight, and then the following afterimage evaluation was performed.

<Afterimage evaluation by long-term AC drive>
An AC voltage of ± 5 V was applied to the FFS-driven liquid crystal cell at a constant temperature of 60 ° C. at a frequency of 30 Hz for 120 hours (hereinafter, the “FFS-driven liquid crystal cell” is also referred to as a “liquid crystal cell”). 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 it to stand, the liquid crystal cell is placed between two polarizing plates arranged so that the 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 at which the second region of the first pixel became the darkest to the angle at which the first region became the darkest was calculated as the angle Δ. Similarly, in the second pixel, the second region and the first region were compared, and the same angle Δ was calculated. Then, the average value of the angles Δ of the first pixel and the second pixel was calculated as the angle Δ of the liquid crystal cell.
When the angle Δ of the liquid crystal cell obtained above was 0.10 ° or more, it was evaluated as “x”, and when it was less than 0.10 °, it was evaluated as “〇”.

<Rubbing resistance test>
Next, a rubbing resistance test was conducted to confirm the strength of the liquid crystal alignment film formed by using the liquid crystal alignment agents obtained in Examples 1 and 2 and Comparative Example 1.
The liquid crystal alignment agents (AL-1) to (AL-3) obtained in Comparative Example 1 and Examples 1 and 2 were applied to the ITO surface of a glass substrate having an ITO electrode on the entire surface by spin coating. After drying on a hot plate at 80 ° C. for 2 minutes, baking was performed at 230 ° C. for 30 minutes using an IR oven to form a coating film having a thickness of 100 nm. The surface of the coating film was irradiated with polarized ultraviolet rays at 300 mJ / cm ² to perform an orientation treatment. Firing was performed again at 230 ° C. for 30 minutes using an IR oven to obtain a substrate with a liquid crystal alignment film.
The substrate with the liquid crystal alignment film obtained as described above is rubbed with a rayon cloth (roller diameter: 120 mm, roller rotation speed: 1000 rpm, moving speed: 20 mm / sec, pushing length: 0.6 mm), and then a microscope. Observation was performed and the rubbing resistance of the liquid crystal alignment film was evaluated.
Those with no rubbing streaks on the film surface were evaluated as "○", and those with streaks were evaluated as "x".

Table 1 below shows the evaluation results of the afterimage evaluation for the FFS-driven liquid crystal cell and the evaluation results of the rubbing resistance test of the liquid crystal alignment film in Comparative Example 1 and Examples 1 and 2.

In order to confirm whether the liquid crystal alignment agent is a liquid crystal alignment agent in which solid content does not precipitate during low temperature storage, the cross-linking agent solutions (Sol-1) to (Sol-3) of Comparative Example 2 and Examples 3 to 4 are used. , The following low temperature storage stability test was performed.

<Low temperature storage stability test>
The cross-linking agent solutions (Sol-1) to (Sol-3) obtained in Comparative Example 2 and Examples 3 to 4 were allowed to stand at −20 ° C. for 2 days, and a test was conducted to evaluate the low temperature storage stability.
After 2 days, the precipitation state of the solution was observed, and if no precipitation was observed, it was judged that the low temperature storage stability was practically good, and the evaluation was "○". On the other hand, when precipitation was observed, it was judged that the low temperature storage stability was poor, and it was evaluated as "x". The results are shown in Table 2 below.

As shown in Tables 1 and 2, AD-2 having an alkylamide moiety and having an alkyl group on N of the amide group, or AD-3 having an alkylamide moiety and having an ethylene glycol chain is oriented. It was found that when applied to the agent, a good liquid crystal orientation and high rubbing resistance can be imparted, and an orientation agent having excellent low temperature storage stability can be formed.

The liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention can be suitably used for various liquid crystal display elements represented by IPS drive type and FFS drive type liquid crystal display elements. These display elements are not limited to liquid crystal displays intended for display, and are also useful in dimming windows and optical shutters that control the transmission and blocking of light.

Claims

A liquid crystal alignment agent containing the following component (A) and component (B).
(A) Component: Polymer (A) having the ability to orient the liquid crystal display
Component (B): Hydroxyalkylamide compound (B) represented by the following formula (1)

(R is an alkyl group having 1 to 6 carbon atoms, R 1 and R 2 are independently hydrogen atoms or monovalent organic groups having 1 to 6 carbon atoms, and A is a divalent organic group having 1 to 30 carbon atoms. Represents.)
The liquid crystal alignment agent according to claim 1, wherein R 2 is a hydrogen atom in the formula (1).
The liquid crystal alignment agent according to any one of claims 1 to 2, wherein A is a divalent hydrocarbon group having 1 to 30 carbon atoms in the above formula (1).
The liquid crystal alignment agent according to any one of claims 1 to 3, wherein the hydroxyalkylamide compound (B) is any of the compounds represented by the following formulas (b-1) to (b-3).
A liquid crystal alignment agent containing the following (A') component and (B') component.
(A') component: Polymer (A') having the ability to orient the liquid crystal display.
Component (B'): Hydroxyalkylamide compound (B') represented by the following formula (1')

(R 'is a group "* -C (R 2') 2 -C (R 1 ') 2 -OH " (* represents a bond .R 1', R 2 'each independently represent a hydrogen atom or It represents a monovalent organic group having 1 to 6 carbon atoms.), And a plurality of R's may be the same or different. N is an integer of 1 to 30. L 1 'is a divalent organic group having 1 to 10 carbon atoms, more L 1' may be the same or different.)
The liquid crystal alignment agent according to claim 5, wherein the hydroxyalkylamide compound (B') is any of the compounds represented by the following formulas (b'-1) to (b'-5).
Claims 1 to 6 wherein the polymer (A) or the polymer (A') is at least one polymer selected from the group consisting of a polyimide precursor and a polyimide which is an imidized product of the polyimide precursor. The liquid crystal alignment agent according to any one of the above items.
The liquid crystal alignment agent according to claim 7, wherein the polyimide precursor is obtained by using a tetracarboxylic acid component containing a tetracarboxylic dianhydride represented by the following formula (2).

(X represents a structure selected from the following equations (x-1) to (x-13).)

(R 1 to R 4 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, and a fluorine atom. It represents a monovalent organic group or a phenyl group having 1 to 6 carbon atoms. R 5 and R 6 independently represent a hydrogen atom or a methyl group. J and k are integers of 0 or 1. , a 1 and a 2 are each independently a single bond, -O -, - CO -, -. COO-, a phenylene group, a sulfonyl group or an more a 2 an amide group, are different from each identical * 1 is a bond that binds to one acid anhydride group, and * 2 is a bond that binds to the other acid anhydride group.)
The liquid crystal alignment agent according to claim 8, wherein the formula (x-1) is selected from the group consisting of the following formulas (x1-1) to (x1-6).

(* 1 is a bond that binds to one acid anhydride group, and * 2 is a bond that binds to the other acid anhydride group.)
The present invention according to any one of claims 7 to 9, wherein the polyimide precursor is obtained by using a diamine component containing at least one diamine selected from the diamines represented by the following formulas (3) and (3i). The liquid crystal alignment agent described.

(Y 3 represents a divalent organic group represented by the following formula (O). R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Y 3i is represented by the following formula (O'). Represents a divalent organic group.)

(Ar represents a divalent benzene ring, a biphenyl structure, or a naphthalene ring. The two Ars may be the same or different, and any hydrogen atom in the ring may be substituted with a monovalent substituent. .p is .Q 3 is an integer of 0 or 1 - (CH 2) n - (. n is an integer of 2 to 18), or the - (CH 2) n - at least - -CH 2 of Represents a group in which a part is replaced with either -O-, -C (= O)-or -OC (= O)-. * Represents a bond.)

(Ar'represents a divalent benzene ring or biphenyl structure. The two Ar's may be the same or different, and any hydrogen atom in the ring may be substituted with a monovalent substituent. p 'is an integer of 0 or 1 .Q 3' is - (CH 2) n - (. n is an integer of 2 to 18), or the - (CH 2) n - of - -CH 2 of Represents a group in which at least a part is replaced with either -O-, -C (= O)-or -OC (= O)-. * Represents a bond.)
The liquid crystal alignment agent according to claim 10, wherein the divalent organic group represented by the formula (O) is any of the following formulas (o-1) to (o-16).

("*" In the formula indicates the bond position.)
The polyimide precursor is a diamine having at least one nitrogen-containing structure selected from the group consisting of a nitrogen-containing heterocycle (excluding the imide ring of the polyimide), a secondary amino group and a tertiary amino group. The liquid crystal alignment agent according to any one of claims 7 to 11 obtained by using the contained diamine component.
A method for producing a liquid crystal alignment film, wherein the liquid crystal alignment agent according to any one of claims 1 to 12 is applied to a substrate, fired, and the obtained film is irradiated with polarized radiation.
The method for producing a liquid crystal alignment film according to claim 13, which is fired at a temperature of 150 to 250 ° C.
A liquid crystal alignment film formed from the liquid crystal alignment agent according to any one of claims 1 to 12.
A liquid crystal display element provided with the liquid crystal alignment film according to claim 15.
The liquid crystal display element according to claim 16, which is an IPS drive system or an FFS drive system.