TWI890820B - Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element - Google Patents

Abstract

The present invention provides a liquid crystal alignment agent for obtaining a liquid crystal alignment film that suppresses variations (non-uniformity) in the liquid crystal alignment property within the liquid crystal alignment film even when the amount of light irradiation during alignment treatment using a photo-alignment method is reduced. The liquid crystal alignment agent is characterized by containing a polymer (A) selected from the group consisting of a polyimide precursor obtained by using a diamine component and a tetracarboxylic acid derivative component, and an imide compound of the polyimide precursor, i.e., a polyimide, wherein the diamine component contains at least 5 mol% of a diamine represented by the following formula (1) based on 1 mol of the diamine component used, and the tetracarboxylic acid derivative component contains an alicyclic tetracarboxylic dianhydride represented by the following formula (T) or a derivative thereof. Any hydrogen atom on the benzene ring may be substituted with a monovalent substituent. X is as defined in the instructions.

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 device.

Liquid crystal display devices have long been used as display components for personal computers, smartphones, portable phones, and televisions. Liquid crystal display devices include, for example, a liquid crystal layer sandwiched between a device substrate and a color filter substrate, pixel electrodes and a common electrode for applying an electric field to the liquid crystal layer, an alignment film for controlling the alignment of the liquid crystal molecules in the liquid crystal layer, and thin-film transistors (TFTs) for switching the electrical signals supplied to the pixel electrodes. Known methods for driving liquid crystal molecules include longitudinal electric field methods such as TN (Twisted Nematic) and VA (Vertical Alignment), and transverse electric field methods such as IPS (In-Plane Switching) and FFS (Fringe Field Switching).

At present, the most popular liquid crystal alignment film in the industry is produced by rubbing the surface of a film composed of polyamide and/or polyimide obtained by imidization, which has been formed on an electrode substrate, in one direction with a cloth such as cotton, nylon, or polyester. Rubbing treatment is a simple and industrially useful method with excellent productivity. However, with the high performance, high precision, and large-scale development of liquid crystal display devices, various problems have emerged, such as scratches, dust, mechanical force, and static electricity on the surface of the alignment film caused by rubbing treatment, and the unevenness within the alignment treatment surface. As an alignment treatment method alternative to rubbing treatment, a photoalignment method is known, which imparts alignment ability to liquid crystals by irradiating them with polarized radiation. Regarding photoalignment methods, some have proposed utilizing photoisomerization reactions, photocrosslinking reactions, and photodecomposition reactions (e.g., see Non-Patent Document 1, Patent Document 1, and Patent Document 2). [Prior Art Documents] [Patent Documents]

[Patent Document 1] Japanese Patent Application Laid-Open No. 9-297313 [Patent Document 2] Brochure No. WO2016/152928 [Non-Patent Document]

[Non-patent document 1] "Liquid Crystal Photo-Alignment Film," Kidowaki and Ichimura, Functional Materials, Vol. 17, No. 11, November 1997, pp. 13-22

(The problem to be solved)

When using photo-alignment methods for alignment processing, the amount of light exposure becomes a factor that affects energy costs and production speed, so it is better to be able to perform alignment processing with a low exposure. However, according to the research of the inventors of this case, even if a liquid crystal alignment agent can obtain good liquid crystal alignment under conditions of high exposure, when the light exposure is reduced, the liquid crystal alignment within the liquid crystal alignment film surface is prone to variation (non-uniformity), and the variation of the twist angle of the liquid crystal within the surface of the liquid crystal display element will also increase. Therefore, when the liquid crystal display element implements a black display, the brightness within the surface will vary, and there is a concern that the display quality will be reduced.

Furthermore, the liquid crystal alignment film used in IPS drive method and FFS drive method liquid crystal display elements also needs to have an alignment control capability to suppress the afterimage (hereinafter also referred to as AC afterimage) caused by long-term AC drive.

The present invention aims to provide a liquid crystal alignment film that suppresses variations (non-uniformity) in the liquid crystal alignment properties within the surface of the liquid crystal alignment film even when the amount of light irradiated during alignment treatment using a photo-alignment method is reduced, a liquid crystal alignment agent for obtaining the liquid crystal alignment film, and a liquid crystal display device using the liquid crystal alignment film. Furthermore, the present invention aims to provide a liquid crystal alignment film that has excellent liquid crystal alignment control that suppresses AC afterimages, a liquid crystal alignment agent for obtaining the liquid crystal alignment film, and a liquid crystal display device using the liquid crystal alignment film. (Means of Solution)

The inventors of this case have diligently researched to achieve the above-mentioned objectives and have discovered that a liquid crystal alignment film formed from a liquid crystal alignment agent containing a polymer obtained by using specific amounts of a specific diamine and a specific alicyclic tetracarboxylic dianhydride as essential components is extremely effective in achieving the above-mentioned objectives, thereby completing the present invention.

The present invention includes the following aspects. A liquid crystal alignment agent characterized by comprising a polymer (A), wherein the polymer (A) is at least one selected from the group consisting of a polyimide precursor obtained by using a diamine component and a tetracarboxylic acid derivative component, and an imide compound of the polyimide precursor, wherein the diamine component comprises at least 5 mol% of a diamine represented by the following formula (1) per mol of the diamine component used, and wherein the tetracarboxylic acid derivative component comprises an alicyclic tetracarboxylic dianhydride represented by the following formula (T) or a derivative thereof; [Chemical 1] Any hydrogen atom on the benzene ring can also be replaced by a monovalent substituent; [Chemistry 2] X represents a structure selected from the group consisting of the following formulae (x-1) to (x-7); [Chemical 3] ^R1 - ^R4 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1-6 carbon atoms, an alkenyl group having 2-6 carbon atoms, an alkynyl group having 2-6 carbon atoms, a monovalent organic group having 1-6 carbon atoms containing a fluorine atom, or a phenyl group; ^R5 and ^R6 each independently represent a hydrogen atom or a methyl group; *1 represents the bond to one of the anhydride groups, and *2 represents the bond to the other anhydride group. (Effects of the Invention)

According to the present invention, a liquid crystal alignment film, a liquid crystal alignment agent for obtaining the same, and a liquid crystal display device using the same are provided, which suppresses variations (non-uniformity) in the liquid crystal alignment properties within the surface of the liquid crystal alignment film even when the amount of light irradiation during alignment treatment using a photo-alignment method is reduced. Furthermore, a liquid crystal alignment film having excellent liquid crystal alignment control that suppresses AC afterimages, a liquid crystal alignment agent for obtaining the same, and a liquid crystal display device using the same are provided. The mechanism by which the present invention achieves the above-mentioned effects is not yet understood; the following is believed to be one of the contributing factors. That is, the polymer of the present invention has a structure formed by direct bonds between urea bonds and benzene rings, and the obtained polymer has a relatively rigid structure. Therefore, it is believed that the variation of liquid crystal alignment within the liquid crystal alignment film surface is reduced and it is also effective in suppressing AC afterimages.

In this specification, examples of halogen atoms include fluorine, chlorine, bromine, and iodine. In this specification, Boc represents a tert-butoxycarbonyl group.

The following describes in detail a liquid crystal alignment agent containing a polymer obtained using specific amounts of a specific diamine and a specific alicyclic tetracarboxylic dianhydride as essential components, a liquid crystal alignment film formed using the liquid crystal alignment agent, and a liquid crystal display device having the liquid crystal alignment film. However, the description of the constituent elements described below is provided as an example of an embodiment of the present invention and is not intended to be limiting.

(Liquid Crystal Alignment Agent) The liquid crystal alignment agent of the present invention contains a polymer (A). Preferred embodiments of the liquid crystal alignment agent of the present invention include a liquid crystal alignment agent containing the polymer (A) and an organic solvent. Also, the liquid crystal alignment agent of the present invention may contain a polymer other than polymer (A) (e.g., polymer (B) described below).

<Polymer (A)> Polymer (A) is at least one polymer selected from the group consisting of a polyimide precursor obtained by using a diamine represented by formula (1) (hereinafter also referred to as a specific diamine) containing 5 mol% or more of a diamine component per mol of the diamine component used, and a tetracarboxylic acid derivative component containing an alicyclic tetracarboxylic dianhydride or a derivative thereof represented by formula (T), and an imide compound of such a polyimide precursor, i.e., a polyimide. Specific examples of such a polymer include a polyimide precursor having an imide precursor structure such as polyamic acid and polyamic acid ester, and an imide compound of such a polyimide precursor, i.e., a polyimide.

<<Specific diamine>> The specific diamine used in the present invention is a diamine represented by the following formula (1). [Chemical 4] Any hydrogen atom on the benzene ring may be substituted with a monovalent substituent.

Examples of the monovalent substituent on the benzene 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, a fluoroalkyl group having 1 to 10 carbon atoms, a fluoroalkenyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, a carboxyl group, an alkoxycarbonyl group having 1 to 10 carbon atoms, a cyano group, and a nitro group.

Considering the viewpoint of improving the liquid crystal alignment, if we enumerate the preferred specific diamines, for example, the diamines represented by the following formulas (1-1) to (1-3), but are not limited thereto. [Chemistry 5]

<<Diamine component>> In order to obtain the diamine component of the polymer (A), at least one diamine represented by the above formula (1) is contained in an amount of 5 mol% or more relative to 1 mol of the diamine component used. The diamine component may be composed of one diamine or two or more diamines. When the diamine component is composed of two or more diamines, the diamine represented by formula (1) and a diamine other than the diamine represented by formula (1) may be contained simultaneously. The compound represented by the following formula (1) may be used alone or in combination of two or more. In order to obtain the diamine component of the polymer (A), the proportion of the diamine represented by formula (1) relative to 1 mol of the diamine component used is preferably 5 to 100 mol%, more preferably 5 to 99 mol%, and even more preferably 5 to 70 mol%. From the viewpoint of improving the liquid crystal alignment, it is more preferably 10 to 60 mol%.

Regarding the diamine component for obtaining polymer (A), the diamine used together with the diamine represented by formula (1) is not particularly limited, and examples thereof include compounds represented by formula (2) or formula (2i). The compounds represented by formula (2) and formula (2i) may be used alone or in combination of two or more.

[Chemistry 6] _Y2 represents a divalent organic group represented by the following formula (O). The two Rs each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. The two _Y2i each independently represent a divalent organic group represented by the following formula (O'). [Chemistry 7] Ar represents a divalent benzene ring, biphenyl structure, or naphthalene ring. The two Ars may be the same or different, and any hydrogen atom in the benzene ring, biphenyl structure, or naphthalene ring may be substituted with a monovalent substituent. p is an integer of 0 or 1. _Q2 represents -( _CH2 ) _n- (n is an integer of 2 to 18), or a group obtained by replacing at least a portion of the _-CH2- in the -( _CH2 ) _n- with -O-, -C(=O)-, or -OC(=O)-. * represents a bonding hand. [Chemistry 8] 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 benzene ring or biphenyl structure may be substituted with a monovalent substituent. p' is an integer of 0 or 1. _{Q 2'} represents -(CH ₂ ) _n - (n is an integer of 2 to 18), or a group obtained by replacing at least a portion of the -CH ₂ - in -(CH ₂ ) _n - with -O-, -C(═O)-, or -OC(═O)-. * represents a bonding hand.

Substituents on the benzene ring, biphenyl structure, or naphthyl ring include, for example, 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, a fluoroalkyl group having 1 to 10 carbon atoms, a fluoroalkenyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, a carboxyl group, a hydroxyl group, an alkoxycarbonyl group having 1 to 10 carbon atoms, a cyano group, and a nitro group.

Regarding the divalent organic group represented by formula (O), from the perspective of improving the liquid crystal alignment, the divalent organic group represented by the following formulas (o-1) to (o-16) is preferred. Wherein, * represents a bond.

[Chemistry 9]

[Chemistry 10] In formula (o-14), the two m's each independently represent an integer from 1 to 3.

[Chemistry 11]

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 improving the liquid crystal alignment.

When two or more diamines represented by the above formula (2) are used, a combination in which Y ₂ is a divalent organic group represented by the above formulas (o-1) to (o-14), i.e., a diamine of the formula (2) and Y ₂ is a divalent organic group represented by the above formulas (o-15) to (o-16), i.e., a diamine of the formula (2) is preferred.

Preferred specific examples of the diamine represented by the above formula (2i) include the compounds represented by the following formulas (2i-1) to (2i-5).

[Chemistry 12] In formula (2i-1) and formula (2i-2), the two n's each independently represent an integer from 1 to 6. In formula (2i-3), the two n's each independently represent an integer from 2 to 6.

From the perspective of achieving the effects of the present invention, the total content of the diamine represented by formula (2) and the diamine represented by formula (2i) is preferably 1 to 95 mol%, more preferably 30 to 95 mol%, and even more preferably 40 to 90 mol%, relative to 1 mol of the diamine component used in the synthesis of polymer (A). When two or more diamines represented by formula (2) are used, the total content of the diamine of formula (2) in which Y ₂ is a divalent organic group represented by formula (o-1) to (o-14) and the diamine of formula (2) in which Y ₂ is a divalent organic group represented by formula (o-15) to (o-16) is preferably 1 to 95 mol%, more preferably 30 to 95 mol%, and even more preferably 40 to 90 mol%, relative to 1 mol of the diamine component used in the synthesis of polymer (A). Furthermore, from the perspective of improving the contrast of liquid crystal display devices, the upper limit of the diamine represented by formula (2) and each diamine represented by formula (2i) relative to 1 mol of the diamine component used in the synthesis of polymer (A) can be 50 mol% or less, preferably 40 mol% or less, and even more preferably 30 mol% or less.

To improve the voltage retention of the resulting liquid crystal alignment display device, polymer (A) may also contain a "-N(D)-" (D represents a carbamate-based protective group)" group within the molecule. Polymer (A) containing the "-N(D)-" (D represents a carbamate-based protective group)" group can be obtained by using a monomer containing the "-N(D)-" (D represents a carbamate-based protective group)" group in at least a portion of the raw materials, or by using a capping agent as described below. The monomer containing the "-N(D)-" group can be, for example, a diamine containing the "-N(D)-" group. Examples of the carbamate-based protective group include tert-butyloxycarbonyl and 9-fluorenylmethoxycarbonyl.

The diamine having the group "-N(D)-(D represents a carbamate-based protective group)" is preferably a diamine having at least one aromatic group such as a benzene ring. More preferably, the diamine has at least one aromatic group such as a benzene ring and the residue other than the group "(D)" has 6 to 30 carbon atoms. Specific examples of the diamine having the group "-N(D)-(D represents a carbamate-based protective group)" include compounds represented by the following formulas (5-1) to (5-10). [Chemistry 13]

From the perspective of improving the voltage holding ratio of a liquid crystal display device, the proportion of the diamine having the group "-N(D)- (D represents a carbamate-based protective group)" is preferably 1 mol% or greater, and more preferably 2 mol% or greater, per 1 mol of the diamine component used in synthesizing the polymer (A). Furthermore, this proportion is preferably 50 mol% or less, more preferably 40 mol% or less, and even more preferably 35 mol% or less.

As the diamine component for obtaining the polymer (A), diamines other than the diamine represented by the above formula (1), the diamine represented by the above formula (2) or the formula (2i), or the diamine having the group "-N(D)- (D represents a carbamate-based protective group)" may be used. Other diamines include the following diamines. 4,4'-Diaminoazobenzene and the following formulas (d _T -1) to (d _T -3) and other diamines having a photoalignment group; 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 diamine compounds represented by the following formulas (3b-1) to (3b-4) and other diamines having a carboxyl group; 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ketone, 1,4-bis(4-aminobenzyl)benzene, 4,4'-diaminodiphenyl ether, 1-(4- Diamines with urea bonds, such as those represented by the following formulas (h-1) to (h-3); diamines with amide bonds, such as those represented by the following formulas (h-4) to (h-6); diamines with photopolymerizable groups at the end, such as 2-(2,4-diaminophenoxy)ethyl methacrylate and 2,4-diamino-N,N-diallylaniline; diamines with siloxane bonds, such as 1,3-bis(3-aminopropyl)-tetramethyldisiloxane; diamines with oxazoline structures, such as those represented by the following formulas (Ox-1) to (Ox-2). [Chemistry 14] [Chemistry 15] In formula (3b-1), ^A1 represents a single bond, _-CH2- , -C2H4-, -C( _CH3 ) _2- , _-CF2- , -C(CF3) _2- , -O-, _-CO- , -NH-, -N( _CH3 ) _- , -CONH- _, -NHCO-, -CH2O-, -OCH2-, -COO-, -OCO-, -CON( _{CH3 )} -, or -N(CH3)CO-; m1 and m2 each independently represent an integer from 0 to 4, and m1 + m2 represents an integer from 1 to 4. In formula ( _3b - ₂ ), m3 and m4 each independently represent an integer from 1 to 5. In formula (3b-3), ^A2 represents a linear or branched alkyl group having 1 to 5 carbon atoms, and m5 represents an integer from 1 to 5. In formula (3b-4), ^A3 and ^A4 each independently represent a single bond, _-CH2- , _-C2H4- , -C(CH3) _2- , _-CF2- , -C( _{CF3 )2- ,} -O-, -CO-, -NH-, -N( _CH3 )-, -CONH-, -NHCO-, _-CH2O- , _-OCH2- , -COO-, -OCO-, -CON( _CH3 )-, or -N( _CH3 )CO-, and m6 represents an integer from 1 to 4. _[ Chemistry 16] [Chemistry 17]

<<Tetracarboxylic Acid Derivative Component>> When producing the above-mentioned polymer (A), the tetracarboxylic acid derivative component that reacts with the diamine component can be not only tetracarboxylic dianhydride but also derivatives of tetracarboxylic dianhydride such as tetracarboxylic acid dihalides, tetracarboxylic acid dialkyl esters, or tetracarboxylic acid dialkyl ester dihalides. The tetracarboxylic acid derivative component can be a single tetracarboxylic dianhydride or its derivatives, or a combination of two or more.

To obtain the tetracarboxylic acid derivative component of polymer (A), an alicyclic tetracarboxylic dianhydride or its derivative represented by formula (T) is included. The alicyclic tetracarboxylic dianhydride or its derivative represented by formula (T) may be composed of a single tetracarboxylic dianhydride or its derivative, or may be composed of two or more tetracarboxylic dianhydrides or their derivatives. In the present invention, the alicyclic tetracarboxylic dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxyl groups, including at least one carboxyl group bonded to an alicyclic structure. However, none of these four carboxyl groups are bonded to an aromatic ring. Furthermore, the alicyclic tetracarboxylic dianhydride need not be composed solely of an alicyclic structure; a portion thereof may have a chain hydrocarbon structure or an aromatic ring structure. Aromatic tetracarboxylic dianhydrides are dianhydrides obtained by intramolecular dehydration of four carboxyl groups, including at least one carboxyl group bound to an aromatic ring. However, they need not consist solely of aromatic ring structures; they may also partially contain a chain hydrocarbon structure or an alicyclic structure. Non-cyclic aliphatic tetracarboxylic dianhydrides are dianhydrides obtained by intramolecular dehydration of four carboxyl groups bound to a chain hydrocarbon structure. However, they need not consist solely of a chain hydrocarbon structure; they may also partially contain an alicyclic structure or an aromatic ring structure.

In preferred embodiments of the alicyclic tetracarboxylic dianhydride or its derivative represented by the above formula (T), X is preferably represented by the above formulas (x-1) to (x-6), and more preferably represented by the above formula (x-1).

Among the above formula (X-1), the one selected from the group consisting of the following formulas (X1-1) to (X1-6) is preferred. From the perspective of improving the liquid crystal alignment, the following formula (X1-1) is even more preferred. [Chemical 18] *1 is the bond to one of the anhydride groups, and *2 is the bond to the other anhydride group.

The proportion of the alicyclic tetracarboxylic dianhydride or its derivative represented by formula (T) above, relative to 1 mol of the total tetracarboxylic acid derivative components used in the synthesis of polymer (A), is preferably 10-100 mol%, more preferably 20-100 mol%, and even more preferably 50-100 mol%. The tetracarboxylic dianhydride or its derivative used in the production of polymer (A) may also contain tetracarboxylic dianhydrides or their derivatives other than the alicyclic tetracarboxylic dianhydride or its derivative represented by formula (T) above (hereinafter referred to as other tetracarboxylic dianhydrides or their derivatives). For example, the other tetracarboxylic dianhydride or its derivative is represented by formula (2T) below. These tetracarboxylic dianhydrides or their derivatives may be used alone or in combination.

[Chemistry 19] _X2 represents a structure selected from the group consisting of the following formulae (x-8) to (x-13) and the following formulae (t-1) to (t-26). [Chemistry 21] [Chemistry 22] [Chemistry 23] [Chemistry 24] j and k are integers of 0 or 1, and A ₁ and A ₂ each independently represent a single bond, -O-, -CO-, -COO-, a phenylene group, a sulfonyl group, or an amide group. *1 is a bonding hand bonded to one of the anhydride groups, and *2 is a bonding hand bonded to the other anhydride group. * is a bonding hand bonded to the anhydride group. R ⁸ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group. From the perspective of liquid crystal alignment, R ⁸ is preferably a hydrogen atom, a halogen atom, a methyl group, or an ethyl group, and more preferably a hydrogen atom or a methyl group. In formula (x-13), the two A _2s may be the same or different. In formula (t-8), the six R ^8s may be the same or different.

Preferred specific examples of the above formulas (x-12) and (x-13) include the following formulas (x-14) to (x-29). In the formulas, "*" represents a bonding hand to the anhydride group. [Chemistry 25] [Chemistry 26]

<Polymer (B)> From the perspective of reducing residual DC, the liquid crystal alignment agent of the present invention may also contain a polymer (B) selected from the group consisting of polyimide precursors obtained using a tetracarboxylic acid derivative component and a diamine component, and polyimides obtained by imidating such polyimide precursors (excluding polymer (A)). Specific examples of such polymers include polymers selected from the group consisting of polyimide precursors obtained using a tetracarboxylic acid derivative component and a diamine component that does not contain the aforementioned specific diamine, and polyimides obtained by imidating such polyimide precursors. Specific examples of the aforementioned polyimide precursors include polyamic acid and polyamic acid esters. Polymer (B) can be used alone or in combination of two or more.

In order to obtain the tetracarboxylic acid derivative component of the polymer (B), non-cyclic aliphatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, aromatic tetracarboxylic dianhydride or derivatives thereof can be listed. Specific examples of non-cyclic aliphatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride and aromatic tetracarboxylic dianhydride include the tetracarboxylic dianhydride exemplified in the polymer (A). Among them, the ideal carboxylic acid derivative component is preferably an alicyclic tetracarboxylic dianhydride represented by the above formula (T) or a derivative thereof, or a tetracarboxylic dianhydride represented by the formula (2T) where _X2 is (x-8) to (x-13) or a derivative thereof (hereinafter collectively referred to as the specific tetracarboxylic acid derivative component (b).) The above-mentioned tetracarboxylic acid derivative component can use a single tetracarboxylic dianhydride or a derivative thereof, or can use two or more of them in combination.

To obtain the diamine component of polymer (B), there can be mentioned the diamines exemplified for polymer (A) above (excluding the specific diamines described above), and diamines having at least one nitrogen-containing structure selected from the group consisting of nitrogen-containing heterocyclic rings, diamine groups, and tertiary amine groups (hereinafter also referred to as specific nitrogen-containing structures) (excluding the diamines described in (5-8) above).

The diamine having the above-mentioned specific nitrogen-containing structure may also have a nitrogen-containing heterocyclic ring, for example, pyrrole, imidazole, pyrazole, triazole, pyridine, pyrimidine, pyrimidinium, pyrrole, indole, benzimidazole, purine, quinoline, isoquinoline, azidine, quinazoline, pyrimidinium, tririmidinium, carbazole, acridine, piperidine, piperidine, pyrrolidine, hexamethyleneimine, etc. Among them, pyridine, pyrimidine, pyrimidinium, piperidine, piperidine, quinoline, carbazole, or acridine is preferred.

The diamine having the above-mentioned specific nitrogen-atom-containing structure may also have a diamine group and a tertiary amine group, for example, as represented by the following formula (n).

[Chemistry 27] In the above formula (n), R represents a hydrogen atom or an alkyl group, cycloalkyl group, or aryl group having 1 to 10 carbon atoms. "*" represents a bond to a alkyl group.

In the above formula (n), R is an alkyl group, for example, a methyl group, an ethyl group, or a propyl group. Examples of cycloalkyl groups include cyclohexyl groups, and examples of aryl groups include phenyl groups and tolyl groups. R is preferably a hydrogen atom or a methyl group.

Specific examples of diamines having the above-mentioned specific nitrogen-containing structure include 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, 1,4-bis-(4-aminophenyl)-piperidinium, 3,6-diaminoacridine, N-ethyl-3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, compounds represented by the following formulas (Dp-1) to (Dp-8), and compounds represented by the following formulas (z-1) to (z-18). [Chemistry 28] [Chemistry 29] [Chemistry 30]

Considering the small amount of residual DC residue, the polymer (B) is preferably selected from the group consisting of diamines having a structure containing nitrogen atoms, 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, the above formula (3b-1) to (3b-4) ) having a carboxyl group, such as a diamine compound represented by the formula (h-1), 4-(2-(methylamino)ethyl)aniline, 4-(2-aminoethyl)aniline, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ketone, 4,4'-diaminodiphenyl ether, and a diamine having a urea bond, such as a diamine represented by the formula (h-1) to (h-3) (these diamines are also collectively referred to as diamines (b)).

To minimize residual DC residue, the content of diamine (b) is preferably 1-100 mol%, more preferably 5-100 mol%, per 1 mol of the diamine component used in the synthesis of polymer (B). When diamines other than diamine (b) are present, the total content of diamine (b) is preferably 90 mol% or less, more preferably 80 mol% or less.

From the perspective of minimizing residual DC afterimages, the content ratio of polymer (A) to polymer (B) can be 10/90 to 90/10, 20/80 to 90/10, or 20/80 to 80/20, based on the mass ratio of [polymer (A)]/[polymer (B)].

The usage ratio of the above-mentioned specific tetracarboxylic acid derivative component (b) is preferably 1 to 100 mol%, more preferably 5 to 100 mol%, and even more preferably 10 to 100 mol%, relative to 1 mol of all tetracarboxylic acid derivative components used in the synthesis of the polymer (B).

<Production method of polymer (A) and polymer (B)> The production of polymer (A) or (B) is carried out by reacting the above-mentioned diamine component and tetracarboxylic acid derivative component in a solvent (condensation polymerization). When a portion of polymer (A) or (B) contains an acylamidic acid structure, for example, a polymer having an acylamidic acid structure (polyacylamidic acid) is obtained by reacting a tetracarboxylic dianhydride component with a diamine component. The solvent is not particularly limited as long as it dissolves the generated polymer. Specific examples of the above-mentioned solvent include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, and 1,3-dimethyl-2-imidazolidinone. When the polymer has high solubility in the solvent, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or solvents represented by the following formulas [D-1] to [D-3] can be used. [Chemical 31] In formula [D-1], ^D1 represents an alkyl group having 1 to 3 carbon atoms, in formula [D-2], ^D2 represents an alkyl group having 1 to 3 carbon atoms, and in formula [D-3], ^D3 represents an alkyl group having 1 to 4 carbon atoms.

These solvents can be used alone or in combination. Furthermore, even solvents that do not dissolve the polymer can be mixed with the aforementioned solvents to the extent that the resulting polymer does not precipitate. When reacting the diamine component and the tetracarboxylic acid derivative component in the solvent, the reaction can be carried out at any concentration, but preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The reaction can also be carried out initially at a high concentration, with additional solvent added later. During the reaction, the ratio of the total molar number of the diamine component to the total molar number of the tetracarboxylic acid derivative component is preferably 0.8 to 1.2. As in conventional polycondensation reactions, the closer this molar ratio is to 1.0, the greater the molecular weight of the resulting polymers (A) and (B).

Polymers containing an acylamidoester structure can be obtained by known methods, for example: [I] reacting the polyacylamidoester obtained by the above method with an esterifying agent, [II] reacting a tetracarboxylic acid diester with a diamine, or [III] reacting a tetracarboxylic acid diester dihalide with a diamine.

The imide compound in polymer (A) or (B) contained in the liquid crystal alignment agent of the present invention is obtained by ring-closing the polymer obtained above. The ring-closure ratio (also known as the imidization ratio) of the functional groups possessed by the amide groups or their derivatives in the imide compound does not necessarily need to be 100% and can be adjusted arbitrarily depending on the application and purpose. To enhance the liquid crystal alignment properties, the imidization ratio of polymer (A) is ideally 20-100%, more preferably 50-95%, and more preferably 60-90%.

Methods for obtaining the imidized product include thermal imidization, where the polymer solution obtained in the above reaction is directly heated, or catalytic imidization, where a catalyst is added to the polymer solution. When conducting thermal imidization in solution, the temperature is preferably 100-400°C, more preferably 120-250°C. It is best to remove the water generated by the imidization reaction while removing it from the system.

The catalytic imidization can be carried out by adding an alkaline catalyst and an acid anhydride to the polymer solution obtained from the reaction, preferably at -20 to 250°C, more preferably at 0 to 180°C, while stirring. The amount of alkaline catalyst is preferably 0.5 to 30 molar times, more preferably 2 to 20 molar times, based on the amount of amide groups, and the amount of acid anhydride is preferably 1 to 50 molar times, more preferably 3 to 30 molar times, based on the amount of amide groups. Examples of alkaline catalysts include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine. Pyridine is particularly preferred due to its moderate alkalinity for the reaction to proceed. Examples of acid anhydrides include acetic anhydride, trimellitic anhydride, and pyromellitic anhydride. Acetic anhydride is preferred because it facilitates purification after the reaction. The imidization rate in catalytic imidization can be controlled by adjusting the catalyst amount, reaction temperature, and reaction time.

To recover the imide product from the imidization reaction solution, the reaction solution is placed in a solvent and precipitated. Examples of suitable solvents for precipitation include methanol, ethanol, isopropyl alcohol, acetone, hexane, butyl cellulose, heptane, methyl ethyl ketone, methyl isobutyl ketone, toluene, benzene, and water. The polymer that has been placed in the solvent and precipitated is filtered and recovered, and then dried at room temperature or under normal pressure or reduced pressure. Alternatively, the recovered precipitated polymer can be redissolved in a solvent and reprecipitated. Repeating this operation 2 to 10 times can reduce impurities in the polymer. Solvents at this time include alcohols, ketones, etc. If three or more solvents are selected from these, the purification efficiency will be further improved, which is more ideal.

<Polymer Solution Viscosity and Molecular Weight> For workability, polymers (A) or (B) used in the present invention preferably have a solution viscosity of, for example, 10 to 1000 mPa·s when prepared at a concentration of 10 to 15 mass %, but this is not particularly limited. The polymer solution viscosity (mPa·s) is measured at 25°C using an E-type rotational viscometer using a 10 to 15 mass % polymer solution prepared in a good solvent for the polymer (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

The weight average molecular weight (Mw) of the polymer (A) or (B) as measured by gel permeation chromatography (GPC) is preferably 1,000 to 500,000, more preferably 2,000 to 500,000. Furthermore, the molecular weight distribution (Mw/Mn), represented by the ratio of Mw to the number average molecular weight (Mn) as measured by GPC, is preferably 15 or less, more preferably 10 or less. By falling within this molecular weight range, good alignment and stability of the liquid crystal display device can be ensured.

<Capping Agent> When synthesizing polymers (A) and (B) in this invention, a tetracarboxylic acid derivative component and a diamine component, such as those described above, can be used in combination with an appropriate capping agent to synthesize an end-capped polymer. End-capped polymers have the effect of increasing the film hardness of the liquid crystal alignment film obtained by coating and improving the adhesion between the sealant and the liquid crystal alignment film. In this invention, the ends of polymers (A) and (B) may be, for example, amino groups, carboxyl groups, acid anhydride groups, or derivatives thereof. These amino groups, carboxyl groups, acid anhydride groups, or derivatives thereof can be obtained by conventional condensation reactions or by capping the ends using the following capping agents. For example, the aforementioned derivatives can be similarly obtained using the following capping agents.

End-capping agents, such as acetic anhydride, maleic anhydride, nedic anhydride, phthalic anhydride, itaconic anhydride, cyclohexanedicarboxylic anhydride, 3-hydroxyphthalic anhydride, trimellitic anhydride, 3-((3-trimethoxysilyl)propyl)-3,4-dihydrofuran-2,5-dione, 4,5,6,7-tetrafluoroisobenzofuran-1,3-dione, 4-ethynylphthalic anhydride, etc.; dicarbonic acid diesters such as di-t-butyl dicarbonate and diallyl dicarbonate chlorocarbonyl compounds such as acrylyl chloride, methacrylic chloride, and nicotinyl chloride; monoamine compounds such as aniline, 2-aminophenol, 3-aminophenol, 4-aminosalicylic acid, 5-aminosalicylic acid, 6-aminosalicylic acid, 2-aminobenzoic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, and n-octylamine; monoisocyanate compounds such as ethyl isocyanate, phenyl isocyanate, and naphthyl isocyanate;

The usage ratio of the end-capping agent is preferably 0.01 to 20 mol parts, more preferably 0.01 to 10 mol parts, based on 100 mol parts of the total diamine components used.

<Other Components in the Liquid Crystal Alignment Agent> The liquid crystal alignment agent of the present invention contains a polymer (A) and, if necessary, a polymer (B). In addition to polymers (A) and (B), the liquid crystal alignment agent of the present invention may also contain other polymers. Examples of such other polymers include polyesters, polyamides, polyureas, polyorganosiloxanes, cellulose derivatives, polyacetals, polystyrene or its derivatives, poly(styrene-phenylmaleimide) derivatives, and poly(meth)acrylates.

Liquid crystal alignment agents are used to produce liquid crystal alignment films. To ensure a uniform thin film, they are typically applied as a coating liquid. The liquid crystal alignment agent of the present invention is preferably a coating liquid containing the aforementioned polymer component and an organic solvent. The polymer concentration in the liquid crystal alignment agent can be adjusted appropriately by adjusting the desired film thickness. For a uniform, defect-free film, a concentration of 1% by mass or greater is ideal, while a concentration of 10% by mass or less is preferred for storage stability. A particularly ideal polymer concentration is 2-8% by mass. The content of polymer (A) in the liquid crystal alignment agent can be appropriately adjusted by the liquid crystal alignment agent coating method and the desired liquid crystal alignment film thickness, preferably 2-10% by mass, and particularly preferably 3-7% by mass.

The organic solvent contained in the liquid crystal alignment agent is not particularly limited as long as it can uniformly dissolve the polymer components. Specific examples thereof include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyllactamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylsulfoxide, γ-butyrolactone, γ-valerolactone, 1,3-dimethyl-2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide, N-methyl ... Good solvents include 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, and N-cyclohexyl-2-pyrrolidone (collectively referred to as "good solvents"). Among them, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide, or γ-butyrolactone are preferred. The content of the good solvent is preferably 20-99 mass % of the total solvent contained in the liquid crystal alignment agent, more preferably 20-90 mass %, and even more preferably 30-80 mass %.

Furthermore, the organic solvent contained in the liquid crystal alignment agent is preferably a mixed solvent containing, in addition to the aforementioned solvents, a solvent (also known as a poor solvent) that improves the coating properties and surface smoothness of the coating film during the application of the liquid crystal alignment agent. Specific examples of poor solvents used in combination are as follows, but are not limited thereto. The content of the poor solvent is ideally 1-80% by mass of the total solvent contained in the liquid crystal alignment agent, more preferably 10-80% by mass, and even more preferably 20-70% by mass. The type and content of the poor solvent can be appropriately selected based on the liquid crystal alignment agent coating equipment, coating conditions, coating environment, and the like.

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 glycol monobutyl ether (butyl cellulose), ethylene glycol monoisopentyl ether, ethylene glycol monohexyl ether, propylene glycol monobutyl ether, 1-(2-butoxyethoxy)-2-propanediol alcohol, 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 acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethylene glycol acetate, propylene glycol diacetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, n-butyl lactate, isoamyl lactate, diethylene glycol monoethyl ether, diisobutyl ketone (2,6-dimethyl-4-heptanone), etc.

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

The ideal solvent combinations of good solvents 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, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone, N-ethyl-2-pyrrolidone and propylene glycol diacetate, N,N-dimethyllactamide and diisobutyl ketone, N-methyl-2-pyrrolidone and ethyl 3-ethoxypropionate, N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate, N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether. N-ethyl-2-pyrrolidone and dipropylene glycol dimethyl ether, N,N-dimethyl lactamide and ethylene glycol monobutyl ether, N,N-dimethyl lactamide and propylene glycol diacetate, N-ethyl-2-pyrrolidone and diethylene glycol diethyl ether, N,N-dimethyl lactamide and diethylene glycol diethyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and 4-hydroxy-4-methyl-2-pentanone and diethylene glycol diethyl ether, N-ethyl-2-pyrrolidone and N-methyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone, N-ethyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and 4-Hydroxy-4-methyl-2-pentanone and diisobutyl ketone, N-methyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone and dipropylene glycol monomethyl ether, N-methyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone and propylene glycol diacetate, γ-butyrolactone and 4-hydroxy-4-methyl-2-pentanone and diisobutyl ketone, γ-butyrolactone and 4-hydroxy-4-methyl-2-pentanone and propylene glycol diacetate, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and diisobutyl ketone, N-methyl-2-pyrrolidone and γ-butyrolactone and Propylene glycol monobutyl ether and diisopropyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and diisobutyl carbinol, 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, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether and propylene glycol diacetate, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether and diisobutyl ketone, N-ethyl-2-pyrrolidone and γ-butyrolactone and diisobutyl ketone, N-ethyl-2-pyrrolidone and N,N-dimethyllactamide and diisobutyl ketone, etc.

The liquid crystal alignment agent of the present invention may also contain additional components other than the polymer component and the organic solvent (hereinafter referred to as additive components). Such additive components include: adhesion promoters for improving the adhesion between the liquid crystal alignment film and the substrate, the adhesion between the liquid crystal alignment film and the sealant, compounds for increasing the strength of the liquid crystal alignment film (hereinafter referred to as crosslinking compounds), compounds for promoting imidization, dielectrics for adjusting the dielectric constant and resistance of the liquid crystal alignment film, and conductive substances.

Regarding the above-mentioned crosslinking compound, from the viewpoint of exhibiting good resistance to AC residual image and highly improving film strength, it may be an ethylene oxide group, an propylene oxide group, a protected isocyanate group, a protected isothiocyanate group, a group containing an oxazoline ring structure, a group containing a Meldrum's acid structure, a cyclic carbonate group, a compound having at least one group selected from the group consisting of a group represented by the following formula (d) and a group represented by the following formula (d1), or a compound selected from the compound represented by the following formula (e).

[Chemistry 32] _R2 and _R3 each independently represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH2 _- OH". * represents a bonding pair. R represents 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. Z represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkynyl group having 2 to 6 carbon atoms. A represents an (m+n)-valent organic group having an aromatic ring. R' represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. m represents an integer from 1 to 6, and n represents an integer from 0 to 4.

Specific examples of compounds having an oxirane group include compounds described in paragraph [0037] of Japanese Patent Application Laid-Open No. 10-338880 and compounds having a tricyclic skeleton described in International Publication No. 2017/170483, which have two or more oxirane groups. Examples of such compounds include N,N,N',N'-tetraoxopropyl-m-xylenediamine, 1,3-bis(N,N-dioxopropylaminomethyl)cyclohexane, N,N,N',N'-tetraoxopropyl-4,4'-diaminodiphenylmethane, N,N,N',N'-tetraoxopropyl-p-phenylenediamine, and compounds represented by the following formulas (r-1) to (r-3). [Chemistry 33]

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

Specific examples of compounds having protected isocyanate groups include compounds having two or more protected isocyanate groups described in paragraphs [0046] to [0047] of Japanese Patent Application Publication No. 2014-224978, and compounds having three or more protected isocyanate groups described in paragraphs [0119] to [0120] of International Publication No. 2015/141598. Compounds represented by the following formulas (bi-1) to (bi-3) are also exemplified. [Chemical 34]

Specific examples of compounds having protected isothiocyanate groups include compounds having two or more protected isothiocyanate groups described in Japanese Patent Application Laid-Open No. 2016-200798.

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 compounds having a group containing a Michaelis acid structure include compounds having two or more Michaelis acid structures described in International Publication No. 2012/091088.

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

Examples of the alkyl group having 1 to 3 carbon atoms in R ₂ and R ₃ of the group represented by the above formula (d) include methyl, ethyl, and propyl.

Specific examples of compounds having a group represented by the above formula (d) include compounds having two or more groups represented by the above formula (d) described in International Publication No. 2015/072554, paragraph [0058] of Japanese Patent Application Laid-Open No. 2016-118753, and compounds described in Japanese Patent Application Laid-Open No. 2016-200798. Compounds represented by the following formulas (hd-1) to (hd-8) are also exemplified. [Chemistry 35]

Specific examples of compounds having the group represented by (d1) include the compounds described in International Publication No. 2019/142927, and more preferably, the compounds represented by the following formulas (hd1-1) to (hd1-4). [Chemical 36]

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 alkyl group having 6 to 30 carbon atoms, an (m+n)-valent organic group formed by directly or through a linking group linking an aromatic alkyl group having 6 to 30 carbon atoms, and an (m+n)-valent group having an aromatic heterocyclic ring. Examples of the above aromatic alkyl groups include benzene and naphthalene. Examples of the aromatic heterocyclic ring include the aromatic heterocyclic rings exemplified by the above-mentioned specific nitrogen-containing structures. Examples of the above linking group include an alkylene group having 1 to 10 carbon atoms, a group obtained by removing a hydrogen atom from the alkylene group, a divalent or trivalent cyclohexane ring, and the like. Furthermore, any hydrogen atom in the alkylene group may be substituted with an organic group such as a fluorine atom or a trifluoromethyl group. The C1-5 alkyl group in R' of formula (e) above can be methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, or n-pentyl. 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).

[Chemistry 37]

The above compounds are examples of crosslinking compounds and are not limited thereto. For example, components other than those described above are disclosed on pages 53 [0105] to 55 [0116] of International Publication No. 2015/060357. Furthermore, two or more crosslinking compounds may be combined.

In the liquid crystal alignment agent of the present invention, the content of the crosslinking compound is preferably 0.5 to 20 parts by mass relative to 100 parts by mass of the polymer component contained in the liquid crystal alignment agent. Considering the crosslinking reaction and exhibiting good resistance to AC afterimage, the content is more preferably 1 to 15 parts by mass.

The above-mentioned adhesion promoter, for example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, vinyltrimethoxysilane, Silane, vinyl triethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane Silane coupling agents such as methoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, tris(3-trimethoxysilylpropyl)isocyanurate, and 3-isocyanatepropyltriethoxysilane are used. When using a silane coupling agent, the amount is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, based on 100 parts by mass of the polymer component contained in the liquid crystal alignment agent, in order to exhibit good resistance to AC residual image.

The compounds promoting imidization are preferably compounds (excluding the crosslinking compounds and bonding aids mentioned above) having a basic site (e.g., a primary amine group, an aliphatic heterocycle (e.g., a pyrrolidine skeleton), an aromatic heterocycle (e.g., an imidazole ring, an indole ring), or a guanidine group), or compounds that generate such a basic site upon calcination. More preferably, compounds that generate such a basic site upon calcination are preferred. As a preferred specific example, amino acids in which some or all of the basic sites are protected are listed. Specific examples of the aforementioned amino acids include glycine, alanine, cysteine, methionine, asparagine, glutamine, valine, leucine, phenylalanine, tyrosine, tryptophan, proline, hydroxyproline, arginine, histidine, lysine, and ornithine. A more preferred example of a compound that promotes imidization is N-α-(9-fluorenylmethoxycarbonyl)-N-τ-(tert-butyloxycarbonyl)-L-histidine.

<Liquid crystal alignment film, liquid crystal display element> The liquid crystal alignment film of the present invention is obtained from the above-mentioned liquid crystal alignment agent. The liquid crystal alignment film of the present invention can be used as a horizontal alignment type or vertical alignment type (VA type) liquid crystal alignment film, and is suitable for a liquid crystal alignment film of a horizontal alignment type liquid crystal display element such as an IPS method or an FFS method. The liquid crystal display element of the present invention has the above-mentioned liquid crystal alignment film. The liquid crystal display element of the present invention can be manufactured, for example, by a method comprising the following steps (1) to (4) or steps (1) to (2) and (4).

<Step (1): Applying the liquid crystal alignment agent on the substrate> The liquid crystal alignment agent of the present invention is applied to one side of the substrate provided with the patterned transparent conductive film using an appropriate coating method such as roll coating, spin coating, printing, or inkjet. The substrate is not particularly limited as long as it is a highly transparent substrate. Glass substrates, silicon nitride substrates, and plastic substrates such as acrylic substrates and polycarbonate substrates can also be used. Furthermore, in a reflective liquid crystal display element, if only a single-sided substrate is used, an opaque material such as a silicon wafer can also be used. In this case, the electrodes can also be made of a light-reflecting material such as aluminum. When manufacturing an IPS or FFS liquid crystal element, a comb-tooth type uses a substrate having electrodes formed of a patterned transparent conductive film or metal film and a counter substrate having no electrodes.

Methods for coating the liquid crystal alignment agent on the substrate and forming a film include screen printing, offset printing, flexographic printing, inkjet printing, or inkjet coating. Among them, inkjet coating and film formation are preferred.

<Step (2): Calcination of the coated liquid crystal alignment agent> Step (2) is a step of calcining the liquid crystal alignment agent coated on the substrate to form a film. After the liquid crystal alignment agent is coated on the substrate, the solvent can be evaporated or thermal imidization of polyamine or polyamine ester can be performed using a heating method such as a hot plate, a heat circulation oven, or an IR (infrared) oven. The drying and calcining steps after coating the liquid crystal alignment agent of the present invention can be selected at any temperature and time, and can also be performed multiple times. The drying temperature can be, for example, 40 to 180°C. Considering the viewpoint of shortening the processing time, it can be carried out at 40 to 150°C. The drying time is not particularly limited and can be 1 to 10 minutes or 1 to 5 minutes. When performing thermal imidization of polyamic acid or polyamic acid ester, a calcination step at a temperature range of, for example, 150 to 300°C or 150 to 250°C can be added after the drying step. The calcination time is not particularly limited and can be 5 to 40 minutes or 5 to 30 minutes. If the film after calcination is too thin, the reliability of the liquid crystal display device may be reduced. Therefore, a thickness of 5 to 300 nm is ideal, and 10 to 200 nm is even more ideal.

<Step (3): Alignment treatment of the film obtained in step (2)> Step (3) is a step of performing alignment treatment on the film obtained in step (2) as appropriate. That is, in a horizontal alignment type liquid crystal display element such as the IPS mode or FFS mode, the coating film is subjected to alignment capability imparting treatment. On the other hand, in a vertical alignment type liquid crystal display element such as the VA mode or PSA mode, the formed coating film can be directly used as a liquid crystal alignment film, but the coating film can also be subjected to alignment capability imparting treatment. The alignment treatment methods of the liquid crystal alignment film include friction treatment method and optical alignment treatment method, and the optical alignment treatment method is more ideal. Photo-alignment treatment methods include irradiating the surface of the aforementioned film with radiation biased in a specific direction and, depending on the circumstances, heating the film at a temperature of 150-250°C to impart liquid crystal alignment properties (also known as liquid crystal alignment ability). The radiation can be ultraviolet light or visible light with a wavelength of 100-800nm. Ultraviolet light with a wavelength of 100-400nm is preferred, and 200-400nm is more preferred.

The radiation dose is preferably 1 to 10,000 mJ/ ^cm² , more preferably 100 to 5,000 mJ/ ^cm² , even more preferably 100 to 1500 mJ/ ^cm² , and even more preferably 100 to 1000 mJ/ ^cm² . When using conventional liquid crystal alignment agents, the light dose for alignment treatment is 100 to 5000 mJ/ ^cm² . However, the liquid crystal alignment agent of the present invention can achieve a liquid crystal alignment film with suppressed variations (non-uniformity) in the liquid crystal alignment property within the surface of the liquid crystal alignment film, even with a reduced light dose for alignment treatment. Furthermore, to improve the liquid crystal alignment, the substrate with the film can be heated at 50 to 250°C during radiation exposure. The liquid crystal alignment film produced in this manner can stably align liquid crystal molecules in a specific direction. Alternatively, the liquid crystal alignment film irradiated with polarized radiation in the above method can be contacted with a solvent or heated.

The solvent used in the contact treatment is not particularly limited, as long as it dissolves decomposition products generated from the film by radiation exposure. Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl celecoxib, ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, and cyclohexyl acetate. Among these, water, 2-propanol, 1-methoxy-2-propanol, or ethyl lactate are preferred from the perspectives of versatility and solvent safety, and water, 1-methoxy-2-propanol, or ethyl lactate are even more preferred. The solvent may be a single solvent or a combination of two or more.

The temperature for heat treatment of the irradiated coating is preferably 50-300°C, more preferably 120-250°C, and the time for heat treatment is preferably 1-30 minutes.

<Step (4): Making a liquid crystal cell> Prepare two substrates with liquid crystal alignment films formed as described above, and arrange liquid crystal between the two substrates facing each other. Specifically, the following two methods can be listed. The first method is to first arrange the two substrates facing each other with a gap (cell gap) between them, with the liquid crystal alignment films facing each other. Then, the periphery of the two substrates is bonded together with a sealant, and the liquid crystal composition is injected into the cell gap separated by the substrate surface and the sealant until it contacts the film surface, and then the injection hole is sealed.

The second method is called ODF (One Drop Fill). A UV-curable sealant, for example, is applied to predetermined locations on one of two substrates with a liquid crystal alignment film already formed. A liquid crystal composition is then dripped onto the surface of the liquid crystal alignment film at predetermined locations. The other substrate is then attached with the liquid crystal alignment films facing each other. The liquid crystal composition is then pressed against the entire surface of the substrate until it contacts the film surface. The entire surface of the substrate is then irradiated with UV light to cure the sealant. In both methods, the liquid crystal composition is preferably heated to a temperature where it reaches an isotropic phase and then slowly cooled to room temperature to eliminate any fluid alignment caused by the liquid crystal filling process. Furthermore, when rubbing the coating, the two substrates are positioned so that the rubbing directions of the coatings form a predetermined angle with each other, such as perpendicular or antiparallel. The sealant may be, for example, an epoxy resin containing a hardener and aluminum oxide balls as spacers. Examples of liquid crystals include nematic and lamellar liquid crystals, with nematic liquid crystals being preferred.

Optionally, a liquid crystal display device can be obtained by attaching a polarizing plate to the outer surface of the liquid crystal cell. Examples of polarizing plates attached to the outer surface of the liquid crystal cell include a polarizing film called "H-film" that stretches and aligns polyvinyl alcohol and absorbs iodine, sandwiched between a cellulose acetate protective film, or a polarizing plate composed solely of the H-film. [Example]

The following examples illustrate the present invention in more detail, but the present invention is not limited thereto. The abbreviations of the compounds used and the methods for determining their properties are as follows. "Boc" represents tert-butyloxycarbonyl. "Fmoc" represents 9-fluorenylmethoxycarbonyl.

(Specific diamine) WA-1: A compound represented by the following formula (WA-1):

(Other diamines) A1 to A9: compounds represented by the following formulas (A1) to (A9):

(Tetracarboxylic dianhydride) B1 to B3: compounds represented by the following formulas (B1) to (B3) [Chemical 40]

(Additives) AD-1 to AD-4: Each compound is represented by the following formula (AD-1) to (AD-4):

(Solvent) NMP: N-methyl-2-pyrrolidone BCS: Ethylene glycol monobutyl ether GBL: γ-butyrolactone

(Determination of Molecular Weight) Molecular weight was measured using a room temperature gel permeation chromatography (GPC) apparatus (GPC-101) (manufactured by Showa Denko Co., Ltd.) and columns (KD-803, KD-805) (manufactured by Showa Denko Co., Ltd.) in the following manner. Column temperature: 50°C; Solvent: N,N-dimethylformamide (additives: lithium bromide monohydrate (LiBr· _H2O ) at 30 mmol/L, anhydrous phosphoric acid (orthophosphoric acid) at 30 mmol/L, tetrahydrofuran (THF) at 10 mL/L); Flow rate: 1.0 ml/min; Standard samples for calibration curve creation: TSK standard polyethylene oxide (molecular weight: approximately 900,000, 150,000, 100,000, and 30,000) (manufactured by Tosoh Corporation) and polyethylene glycol (molecular weight: approximately 12,000, 4,000, and 1,000) (manufactured by Polymer Laboratories).

(Viscosity Measurement) The viscosity of the solution was measured at 25°C using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample volume of 1.1 mL and a TE-1 conical rotor (1°34', R24).

<Polymer Synthesis> (Synthesis Example 1) WA-1 (1.26 g, 5.20 mmol), A1 (1.27 g, 5.20 mmol), A3 (1.20 g, 5.20 mmol), A4 (1.79 g, 5.20 mmol), A2 (1.23 g, 5.20 mmol), and B1 (5.48 g, 24.4 mmol) were mixed in NMP (87.9 g) and reacted at 40°C for 3 hours to obtain a polyamide solution with a resin solids concentration of 12% by mass (viscosity: 212 mPa·s). The ratio of WA-1 in the diamine component was 20 mol% per 1 mol of the diamine component. NMP was added to the resulting polyimide solution (30.0 g) to dilute it to a solids concentration of 9.0% by weight. Acetic anhydride (2.39 g) and pyridine (0.618 g) were then added as imidization catalysts and reacted at 65°C for 3 hours. The reaction solution was poured into methanol (220 ml), and the resulting precipitate was filtered. The precipitate was washed with methanol and dried under reduced pressure at 80°C to obtain a polyimide powder. The polyimide had an imidization ratio of 89%, a number average molecular weight of 10,216, and a weight average molecular weight of 43,193. NMP (22.0 g) was added to the obtained polyimide powder (3.00 g), and the mixture was stirred at 80° C. for 15 hours to dissolve the mixture, thereby obtaining a polyimide solution (SPI-1).

(Synthesis Example 2) WA-1 (1.26 g, 5.20 mmol), A1 (2.54 g, 10.4 mmol), A4 (1.79 g, 5.20 mmol), A2 (1.23 g, 5.20 mmol), and B1 (5.48 g, 24.4 mmol) were mixed in NMP (87.3 g) and reacted at 40°C for 3 hours to obtain a polyamide solution with a resin solids concentration of 12% by mass (viscosity: 199 mPa·s). The ratio of WA-1 in the diamine component was 20 mol% per 1 mol of the diamine component. NMP was added to the resulting polyimide solution (30.0 g) to dilute it to a solids concentration of 9.0% by weight. Acetic anhydride (2.33 g) and pyridine (0.602 g) were then added as imidization catalysts and reacted at 60°C for 3 hours. The reaction solution was poured into methanol (210 ml), and the resulting precipitate was filtered. The precipitate was washed with methanol and dried under reduced pressure at 80°C to obtain a polyimide powder. The polyimide had an imidization ratio of 88%, a number average molecular weight of 11,829, and a weight average molecular weight of 42,836. NMP (22.0 g) was added to the obtained polyimide powder (3.00 g), and the mixture was stirred at 80° C. for 15 hours to dissolve the mixture, thereby obtaining a polyimide solution (SPI-2).

(Synthesis Example 3) WA-1 (2.52 g, 10.4 mmol), A1 (2.54 g, 10.4 mmol), A2 (1.23 g, 5.20 mmol), and B1 (5.48 g, 24.4 mmol) were mixed in NMP (86.2 g) and reacted at 40°C for 3 hours to obtain a polyamide solution with a resin solids concentration of 12% by mass (viscosity: 189 mPa·s). The proportion of WA-1 in the diamine component was 40 mol% per 1 mol of the diamine component. NMP was added to the resulting polyimide solution (30.0 g) to dilute it to a solids concentration of 9.0% by weight. Acetic anhydride (2.33 g) and pyridine (0.602 g) were then added as imidization catalysts and reacted at 60°C for 3 hours. The reaction solution was poured into methanol (210 ml), and the resulting precipitate was filtered. The precipitate was washed with methanol and dried under reduced pressure at 80°C to obtain a polyimide powder. The polyimide had an imidization ratio of 88%, a number average molecular weight of 11,194, and a weight average molecular weight of 40,838. NMP (22.0 g) was added to the obtained polyimide powder (3.00 g), and the mixture was stirred at 80° C. for 15 hours to dissolve the mixture, thereby obtaining a polyimide solution (SPI-3).

(Synthesis Example 4) WA-1 (1.89 g, 7.80 mmol), A1 (1.91 g, 7.80 mmol), A6 (0.562 g, 5.20 mmol), A8 (2.07 g, 5.20 mmol), and B1 (5.59 g, 25.0 mmol) were mixed in NMP (86.2 g) and reacted at 40°C for 3 hours to obtain a polyamide solution (PAA-4) with a resin solids concentration of 12% by mass (viscosity: 412 mPa·s). The ratio of WA-1 in the diamine component was 30 mol% per 1 mol of the diamine component. The polymer had a number average molecular weight of 15,832 and a weight average molecular weight of 46,829.

(Synthesis Example 5) WA-1 (1.26 g, 5.20 mmol), A1 (1.91 g, 7.80 mmol), A6 (0.562 g, 5.20 mmol), A8 (3.11 g, 7.80 mmol), and B1 (5.59 g, 25.0 mmol) were mixed in NMP (91.1 g) and reacted at 40°C for 3 hours to obtain a polyamide solution (PAA-5) with a resin solids concentration of 12% by mass (viscosity: 398 mPa·s). The ratio of WA-1 as the diamine component was 20 mol% per 1 mol of the diamine component. The polymer had a number average molecular weight of 16,888 and a weight average molecular weight of 46,001.

(Synthesis Example 6) A9 (4.14 g, 20.8 mmol), A5 (1.55 g, 5.20 mmol), and B3 (4.84 g, 24.7 mmol) were mixed in NMP (94.8 g) and reacted at 40°C for 15 hours to obtain a polyamide solution (PAA-6) with a resin solids concentration of 10% by mass (viscosity: 315 mPa·s). This polymer had a number-average molecular weight of 15,888 and a weight-average molecular weight of 43,741.

(Synthesis Example 7) A9 (4.14 g, 20.8 mmol), A5 (1.55 g, 5.20 mmol), and B2 (7.34 g, 25.0 mmol) were mixed in NMP (95.6 g) and reacted at 70°C for 15 hours to obtain a polyamide solution (PAA-7) with a resin solids concentration of 12% by mass (viscosity: 465 mPa·s). This polymer had a number-average molecular weight of 13,182 and a weight-average molecular weight of 42,252.

(Comparative Synthesis Example 1) A5 (1.55 g, 5.20 mmol), A1 (1.27 g, 5.20 mmol), A3 (1.20 g, 5.20 mmol), A4 (1.79 g, 5.20 mmol), A2 (1.23 g, 5.20 mmol), and B1 (5.48 g, 24.4 mmol) were mixed in NMP (91.8 g) and reacted at 40°C for 3 hours to obtain a polyamide solution with a resin solids concentration of 12% by mass (viscosity: 203 mPa·s). NMP was added to the resulting polyimide solution (30.0 g) and diluted to a solids concentration of 9.0% by weight. Acetic anhydride (2.28 g) and pyridine (0.591 g) were then added as imidization catalysts and reacted at 60°C for 3.5 hours. The reaction solution was poured into methanol (220 ml), and the resulting precipitate was filtered. The precipitate was washed with methanol and dried under reduced pressure at 80°C to obtain a polyimide powder. The polyimide had an imidization ratio of 86%, a number average molecular weight of 11,191, and a weight average molecular weight of 40,381. NMP (22.0 g) was added to the obtained polyimide powder (3.00 g), and the mixture was stirred at 80° C. for 15 hours to dissolve the mixture, thereby obtaining a polyimide solution (SPI-R1).

(Comparative Synthesis Example 2) A8 (2.07 g, 5.20 mmol), A1 (1.91 g, 7.80 mmol), A7 (2.50 g, 7.80 mmol), A6 (0.562 g, 5.20 mmol), and B1 (5.60 g, 25.0 mmol) were mixed in NMP (92.6 g) and reacted at 40°C for 3 hours to obtain a polyamide solution (PAA-R2) with a resin solids concentration of 12% by mass (viscosity: 423 mPa·s). This polymer had a number-average molecular weight of 14,921 and a weight-average molecular weight of 45,956.

<Preparation of Liquid Crystal Alignment Agent> (Example 1) To the polyimide solution (SPI-1) (2.08 g) obtained in Synthesis Example 1, the polyamide solution (PAA-7) (2.08 g) obtained in Synthesis Example 7, GBL (3.00 g), BCS (2.00 g), a 10 wt% NMP dilute solution of AD-1 (0.500 g), AD-2 (0.050 g), AD-3 (0.050 g), and a 1 wt% GBL dilute solution of AD-4 (0.500 g) were added. The mixture was stirred at room temperature for 5 hours to obtain a liquid crystal alignment agent (V-1). This liquid crystal alignment agent showed no abnormalities such as turbidity or precipitation, confirming a homogeneous solution.

(Example 2) NMP (1.67 g), GBL (3.00 g), and BCS (2.00 g) were added to the polyimide solution (SPI-2) (3.33 g) obtained in Synthesis Example 2. The mixture was stirred at room temperature for 2 hours to obtain a liquid crystal aligner (V-2). This liquid crystal aligner showed no abnormalities such as turbidity or precipitation, confirming a homogeneous solution.

(Example 3) A liquid crystal alignment agent (V-3) was obtained in the same manner as in Example 2, except that the polyimide solution (SPI-2) in Example 2 was replaced with a polyimide solution (SPI-3). This liquid crystal alignment agent showed no abnormalities such as turbidity or precipitation, confirming a homogeneous solution.

(Example 4) NMP (3.67g) and BCS (3.00g) were added to the polyamide solution (PAA-4) (3.33g) obtained in Synthesis Example 4. The mixture was stirred at room temperature for 2 hours to obtain a liquid crystal alignment agent (V-4). This liquid crystal alignment agent showed no abnormalities such as turbidity or precipitation, confirming a homogeneous solution.

(Example 5) A liquid crystal alignment agent (V-5) was obtained in the same manner as in Example 4, except that the polyamine solution (PAA-4) in Example 4 was replaced with the polyamine solution (PAA-5). This liquid crystal alignment agent showed no abnormalities such as turbidity or precipitation, confirming a homogeneous solution.

(Example 6) To the polyamine solution (PAA-5) (1.83 g) obtained in Synthesis Example 5, the polyamine solution (PAA-6) (3.30 g) obtained in Synthesis Example 6, NMP (0.770 g), BCS (3.00 g), a 10% by mass NMP dilute solution of AD-1 (0.550 g), and a 1% by mass NMP dilute solution of AD-4 (0.550 g) were added. The mixture was stirred at room temperature for 2 hours to obtain a liquid crystal alignment agent (V-6). This liquid crystal alignment agent showed no abnormalities such as turbidity or precipitation, confirming a homogeneous solution.

(Comparative Example 1) To the polyimide solution (SPI-R1) (2.08 g) obtained in Comparative Example 1, polyamide (PAA-7) (2.08 g) obtained in Synthesis Example 7, GBL (3.00 g), BCS (2.00 g), a 10 wt% NMP dilute solution of AD-1 (0.500 g), AD-2 (0.050 g), AD-3 (0.050 g), and a 1 wt% GBL dilute solution of AD-4 (0.500 g) were added. The mixture was stirred at room temperature for 5 hours to obtain a liquid crystal alignment agent (V-R1). This liquid crystal alignment agent showed no abnormalities such as turbidity or precipitation, confirming a homogeneous solution.

(Comparative Example 2) NMP (1.67g), GBL (3.00g), and BCS (2.00g) were added to the polyamide solution (PAA-R2) (3.33g) obtained in Comparative Synthesis Example 2. The mixture was stirred at room temperature for 2 hours to obtain a liquid crystal alignment agent (V-R2). This liquid crystal alignment agent showed no abnormalities such as turbidity or precipitation, confirming a homogeneous solution.

Using the liquid crystal alignment agent obtained above, an FFS-driven liquid crystal cell was fabricated according to the following procedure and various evaluations were performed. <FFS-driven liquid crystal cell configuration> The FFS-driven liquid crystal cell is composed of a first glass substrate and a second glass substrate. The first glass substrate has an FOP (Finger on Plate) electrode layer formed on its surface, consisting of a planar common electrode, an insulating layer, and a comb-shaped pixel electrode. The second glass substrate has 4μm-high columnar spacers on its surface and an anti-static ITO film on its backside. The pixel electrode has a central portion with a comb-like shape, consisting of a plurality of parallel, 3μm-wide electrode elements bent at an internal angle of 160°, spaced 6μm apart. A single pixel comprises a first region and a second region, bounded by a line connecting the bent portions of the plurality of electrode elements. The liquid crystal alignment film formed on the first glass substrate is oriented so that the direction bisecting the internal angle of the pixel's bent portion is perpendicular to the alignment direction of the liquid crystal. Furthermore, the liquid crystal alignment film formed on the second glass substrate is oriented so that the alignment direction of the liquid crystal on the first substrate aligns with the alignment direction of the liquid crystal on the second substrate during liquid crystal cell fabrication.

Liquid Crystal Cell Fabrication A liquid crystal alignment agent (LCA) filtered through a 1.0μm pore size filter was spin-coated on each surface of the glass substrates in the above set and dried on an 80°C hot plate for 2 minutes. The coated surface was then irradiated with linearly polarized UV light at a wavelength of 254nm with an extinction ratio of 26:1 through a polarizing plate. The substrate was then calcined in a 230°C hot air circulating oven for 30 minutes, resulting in a 100nm thick LC-coated substrate. The UV exposure dose is shown in Tables 1 and 2. Next, a sealant was printed on one of the LC-coated glass substrates in the above set. The other substrate was then bonded together, with the LC-coated surfaces facing each other, and the sealant was cured to form an empty cell. MLC-7026 (Merck) was injected into this empty cell using the reduced pressure injection method. The injection port was sealed to obtain an FFS-driven liquid crystal cell. The resulting liquid crystal cell was then heated at 120°C for one hour and left overnight before evaluating its afterimage characteristics.

<Evaluation of In-Plane Contrast Uniformity> The twist angle of the liquid crystal display device was evaluated using an OPTIPRO-micro manufactured by SHINTEC. The prepared liquid crystal cell was placed on a test stand. With no voltage applied, measurements were taken at 20 points within the first pixel plane. The standard deviation (3σ) was calculated as three times the standard deviation (σ). Small variations in the twist angle indicate small variations in the liquid crystal alignment within the plane of the liquid crystal alignment film. A 3σ value of less than 1.3 was defined as "good," and a value of 1.3 or greater was defined as "poor." The evaluation results for the liquid crystal display devices using the liquid crystal alignment agents of the Examples and Comparative Examples are shown in Table 1.

<Evaluation of Image Posterity Using Long-Term AC Drive> The FFS-driven liquid crystal cells fabricated above were subjected to an AC voltage of ±10V at a frequency of 60Hz for 120 hours in a constant temperature environment at 60°C. The cells were then short-circuited between the pixel electrode and the counter electrode and left in this state at room temperature for one day. For the treated cells, the deviation between the alignment directions of the liquid crystal in the first and second zones of the pixel in the absence of applied voltage (inactive state) was calculated as an angle. Specifically, a liquid crystal cell was placed between two polarizing plates with their polarization axes perpendicular to each other. The backlight was then turned on, and the cell's angle was adjusted to minimize the intensity of light transmitted through the first pixel region. The angle required to rotate the cell to minimize the intensity of light transmitted through the second pixel region was then determined. The afterimage characteristics caused by long-term AC drive were evaluated, with a rotation angle of 0.1° or less being considered "good" and a value greater than 0.1° being considered "poor." The evaluation results for afterimage characteristics are shown in Table 2.

[Table 1] Liquid crystal alignment agent UV exposure (J/cm ² ) Torsion angle standard deviation (3σ) Example 1 V-1 0.25 Good (1.23) Example 2 V-2 0.25 Good (1.25) Example 3 V-3 0.25 Good (1.17) Example 4 V-4 0.25 Good (1.00) Example 5 V-5 0.25 Good (1.00) Example 6 V-6 0.25 Good (1.20) Comparative example 1 V-R1 0.25 Bad (1.37) Comparative example 2 V-R2 0.25 Bad (1.40)

[Table 2] Liquid crystal alignment agent UV exposure (J/cm ² ) Afterimage characteristics Example 4 V-4 0.35 Good (less than 0.1°) Example 5 V-5 0.35 Good (less than 0.1°)

The above results demonstrate that the liquid crystal alignment films obtained using the diamine WA-1 alignment agent exhibit less variation in the liquid crystal alignment properties within the film surface than the liquid crystal alignment films obtained using the diamine A5 alignment agent (V-R1) or the diamine WA-1-free alignment agent (V-R2). This is particularly evident in a comparison of Examples 1-6 and Comparative Examples 1-2 in Table 1. Furthermore, as shown in Table 2, the liquid crystal alignment films obtained using the diamine WA-1 alignment agent exhibit excellent afterimage properties. [Industrial Applicability]

Liquid crystal alignment films obtained from the liquid crystal alignment agent of the present invention can be used in various display devices, such as clocks, portable game consoles, word processors, notebook personal computers, navigation systems, cameras, PDAs, digital cameras, mobile phones, smartphones, various monitors, LCD televisions, and information displays. Furthermore, the polymer composition contained in the liquid crystal alignment agent can also be used as liquid crystal alignment films for retardation films, scanning antennas, liquid crystal array antennas, or liquid crystal alignment films for transmissive scattering liquid crystal dimming devices, as well as in other applications, such as protective films for color filters, gate insulation films for flexible displays, and substrate materials.

In addition, the present invention incorporates the entire contents of the specification, patent application, drawings, and abstract of Japanese Patent Application No. 2020-122979 filed on July 17, 2020, and is incorporated herein by reference as a disclosure of the specification of the present invention.

Claims (17)

A liquid crystal alignment agent characterized by containing a polymer (A), wherein the polymer (A) is at least one selected from the group consisting of a polyimide precursor obtained by using a diamine component and a tetracarboxylic acid derivative component, and an imide compound of the polyimide precursor, i.e., a polyimide; wherein the diamine component contains 5 mol% or more of a diamine represented by the following formula (1) based on 1 mol of the diamine component used; the tetracarboxylic acid derivative component contains an alicyclic tetracarboxylic dianhydride represented by the following formula (T) or a derivative thereof; and the diamine component further contains a diamine represented by the following formula (2) or (2i); Any hydrogen atom on the benzene ring can also be replaced by a monovalent substituent; X represents a structure selected from the group consisting of the following formulas (x-1) to (x-7); ^R1 - ^R4 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1-6 carbon atoms, an alkenyl group having 2-6 carbon atoms, an alkynyl group having 2-6 carbon atoms, a monovalent organic group having 1-6 carbon atoms containing a fluorine atom, or a phenyl group; ^R5 and ^R6 each independently represent a hydrogen atom or a methyl group; *1 represents the bond to one of the anhydride groups, and *2 represents the bond to the other anhydride group; Y ₂ represents a divalent organic group represented by the following formula (O); the two Rs each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; the two Y _2i each independently represent a divalent organic group represented by the following formula (O'); Ar represents a divalent benzene ring, biphenyl structure, or naphthyl ring; the two Ars may be the same or different, and any hydrogen atom in the benzene ring, biphenyl structure, or naphthyl ring may be substituted with a monovalent substituent; p is an integer of 0 or 1; _Q2 represents -( _CH2 ) _n- (n is an integer of 2 to 18), or represents a group in which at least a portion of the _-CH2- of the -( _CH2 ) _n- is substituted with any of -O-, -C(=O)-, or -OC(=O)-; * represents a bond; Ar' represents a divalent benzene ring or a biphenyl structure; two Ar's may be the same or different, and any hydrogen atom of the benzene ring or biphenyl structure may be substituted with a monovalent substituent; p' is an integer of 0 or 1; Q _2' represents -(CH ₂ ) _n - (n is an integer of 2 to 18), or represents a group in which at least a portion of the -CH ₂ - of -(CH ₂ ) _n - is substituted with any of -O-, -C(═O)-, or -OC(═O)-; * represents a bond. The liquid crystal aligner of claim 1, wherein the diamine represented by formula (1) is a diamine represented by the following formulas (1-1) to (1-3); . The liquid crystal alignment agent of claim 1 or 2, wherein 10 to 60 mol% of the diamine component is a diamine represented by formula (1). The liquid crystal aligner of claim 1, wherein the divalent organic group represented by formula (O) is represented by the following formulas (o-1) to (o-16), and the divalent organic group represented by formula (O') is represented by the following formulas (o-7) to (o-16); In formula (o-14), the two m's each independently represent an integer from 1 to 3; . The liquid crystal alignment agent of claim 1 or 2, wherein the polymer (A) has a group "-N(D)-" in the molecule, where D represents a urethane protective group. The liquid crystal alignment agent of claim 1 or 2, wherein the diamine component further comprises a diamine having a group "-N(D)- (D represents a carbamate-based protective group)". The liquid crystal alignment agent of claim 1 or 2 further comprises a polymer (B), wherein the polymer (B) is at least one selected from the group consisting of a polyimide precursor obtained by using a tetracarboxylic acid derivative component and a diamine component that does not contain the diamine represented by formula (1), and an imide compound of the polyimide precursor, i.e., a polyimide. The liquid crystal alignment agent of claim 7, wherein the diamine component used to obtain the polymer (B) includes a diamine having a nitrogen-containing structure selected from at least one of the group consisting of a nitrogen-containing heterocyclic group, a diamine group, and a tertiary amine group. The liquid crystal alignment agent of claim 1 or 2 further comprises at least one additive selected from the group consisting of a crosslinking compound, a capping agent, and an adhesion promoter. The liquid crystal aligner of claim 1 or 2, wherein X is a structure represented by formula (x-1). The liquid crystal alignment agent of claim 1 or 2 is used for a liquid crystal alignment film used in a photo-alignment treatment method. A liquid crystal alignment film is obtained from the liquid crystal alignment agent according to any one of claims 1 to 11. A liquid crystal display device comprises the liquid crystal alignment film of claim 12. A method for manufacturing a liquid crystal alignment film comprises the following steps (1) to (3): step (1): applying a liquid crystal alignment agent as described in any one of claims 1 to 10 on a substrate; step (2): calcining the applied liquid crystal alignment agent; step (3): performing an alignment treatment on the film obtained in step (2). A method for manufacturing a liquid crystal alignment film as claimed in claim 14, wherein the alignment treatment is a photoalignment treatment. The method for manufacturing a liquid crystal alignment film according to claim 15, wherein the radiation exposure in the photo-alignment treatment is 100-1500 mJ/cm ² . In the method for manufacturing a liquid crystal alignment film according to any one of claims 14 to 16, the alignment-treated film is further subjected to a heat treatment at 50 to 300°C.