JP7768150B2 - Liquid crystal alignment agent, liquid crystal alignment film, method for manufacturing liquid crystal display element, and liquid crystal display element - Google Patents

Description

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

Liquid crystal display elements used in LCD televisions, navigation systems, smartphones, and other devices typically incorporate a liquid crystal alignment film to control the alignment of liquid crystal molecules. Liquid crystal alignment films function to align liquid crystal molecules in a specific direction. For example, liquid crystal display elements have a structure in which liquid crystal molecules forming a liquid crystal layer are sandwiched between liquid crystal alignment films formed on the surfaces of a pair of substrates. The liquid crystal molecules are aligned in a specific direction by the liquid crystal alignment film and respond to the application of voltage to electrodes disposed between the substrates and the liquid crystal alignment film. As a result, liquid crystal display elements utilize the alignment changes induced by the response of the liquid crystal molecules to display desired images. To date, polyimide-based liquid crystal alignment films have primarily been used, which are formed by applying a liquid crystal alignment agent, primarily composed of a solution of a polyimide precursor such as polyamic acid (polyamic acid) or a soluble polyimide, to a glass substrate or the like and then baking the applied liquid crystal alignment agent.
In recent years, with the advancement of performance of liquid crystal display elements, in addition to applications such as large-screen, high-definition liquid crystal televisions, liquid crystal display elements are now being used in in-vehicle applications (for example, car navigation systems and meter panels), monitors for surveillance cameras and medical cameras, and in response to demands for better viewing angle characteristics, horizontal electric field systems such as the IPS (In Plane Switching) system and the FFS (Fringe Field Switching) system have been studied (Patent Document 1, Patent Document 2).

International Publication No. 2019-082975 International Publication No. 2020-116585

Liquid crystal alignment films used in IPS-driven and FFS-driven liquid crystal display elements require an alignment control force to suppress image retention (hereinafter also referred to as AC image retention) that occurs due to long-term AC driving. High display quality is becoming increasingly important in liquid crystal display elements, which are rapidly becoming higher-definition, and the specifications for preventing display defects such as "image retention" are becoming increasingly strict.
Furthermore, in the liquid crystal display elements used for the above applications, a lower pretilt angle than conventional ones is required due to the demand for viewing angle characteristics. In Patent Document 1, a liquid crystal alignment film is produced by obtaining a polyimide from a polyamic acid and then using a liquid crystal aligning agent containing the polyimide, but this has the drawback of being costly due to the large number of steps required for preparing the liquid crystal aligning agent.
On the other hand, Patent Document 2 describes that a liquid crystal alignment film obtained from a liquid crystal aligning agent containing two types of polyamic acids has high resistance to AC afterimages. However, the inventors' investigations have revealed that the liquid crystal alignment film does not have a sufficient effect of reducing the pretilt angle.

In view of the above, the present invention aims to provide a cost-effective liquid crystal alignment agent that has excellent resistance to AC image retention and produces a liquid crystal alignment film with low pretilt angle characteristics, a liquid crystal alignment film formed using the liquid crystal alignment agent, and a liquid crystal display element having the liquid crystal alignment film.

As a result of intensive research into achieving the above-mentioned objectives, the inventors discovered that forming a liquid crystal alignment film using a liquid crystal alignment agent containing a specific polymer component is effective in achieving the above-mentioned objectives, leading to the completion of the present invention.

The present invention is based on this finding and has the following gist.
A liquid crystal aligning agent comprising the following components (A) and (B):
Component (A): Polyamic acid (A) which is a reaction product of a tetracarboxylic acid derivative component containing an aromatic tetracarboxylic acid dianhydride in an amount of 100 mol % of the total tetracarboxylic acid derivative component, and a diamine component containing a diamine represented by the following formula (d _AL ):
Component (B): Polyamic acid (B) which is a reaction product of a tetracarboxylic acid derivative component containing at least one tetracarboxylic acid dianhydride selected from the group consisting of acyclic aliphatic tetracarboxylic acid dianhydrides and alicyclic tetracarboxylic acid dianhydrides in an amount of 5 mol % or more of the total tetracarboxylic acid derivative components, and a diamine component containing a diamine represented by the following formula (d _AL ) and a diamine represented by the following formula (d _n ):
(In formula (d _AL ), A represents a divalent organic group having the group "* ₁₁ -(CH ₂ ) _n -O-* ₁₂ " (* ₁₁ represents a bond bonded to an oxygen atom or a bond bonded to a carbon atom constituting a benzene ring, * ₁₂ represents a bond, and n is an integer of 1 to 5). Any hydrogen atom of the benzene ring bonded to the NH ₂ group may be replaced with a monovalent group.)
(In formula (d _n ), Y represents a divalent organic group having a nitrogen-atom-containing structure selected from the group consisting of nitrogen-atom-containing heterocycles and amino groups represented by the group "* ₂₁ -NR-* ₂₂ " (* ₂₁ and * ₂₂ represent bonds bonding to carbon atoms constituting the aromatic ring, provided that the carbon atoms do not form a ring with the nitrogen atom to which R is bonded; R represents a hydrogen atom or a monovalent organic group, and the monovalent organic group is bonded to the nitrogen atom at a carbon atom other than the carbonyl carbon).)

The liquid crystal aligning agent of the present invention can provide a liquid crystal alignment film having excellent resistance to AC afterimages and low pretilt angle characteristics, and is therefore cost-effective. Furthermore, a liquid crystal display device having a liquid crystal alignment film formed using the liquid crystal aligning agent has excellent viewing angle characteristics and high display quality.
Although the mechanism by which the above-described effects of the present invention are obtained is not entirely clear, it is generally assumed as follows: By using two types of polyamic acids as polymer components used in the liquid crystal aligning agent and by using diamines having specific alkylene chain lengths as raw material components for both polyamic acids, a highly linear polymer is obtained, which is thought to be the effect of improving resistance to AC image retention.
Furthermore, it is believed that by using two different types of polyamic acid, the two types of polyamic acid are appropriately compatible with each other, making it possible to achieve both high resistance to AC afterimages and low pretilt angle characteristics.

1 is a schematic cross-sectional view showing an example of a horizontal electric field liquid crystal display element of the present invention. FIG. 10 is a schematic cross-sectional view showing another example of the horizontal electric field liquid crystal display element of the present invention.

Below, we will explain each component contained in the liquid crystal alignment agent of the present disclosure, as well as other components that may be optionally blended as needed.

<Polyamic Acid (A)>
The diamine component used in the production of the polyamic acid (A) contained in the liquid crystal aligning agent of the present invention contains a diamine represented by the following formula (d _AL ): The diamine represented by the formula (d _AL ) may be used alone or in combination of two or more.
(In formula (d _AL ), A represents a divalent organic group having the group "* ₁₁ -(CH ₂ ) _n -O-* ₁₂ " (* ₁₁ represents a bond bonded to an oxygen atom or a bond bonded to a carbon atom constituting a benzene ring, * ₁₂ represents a bond, and n is an integer of 1 to 5). Any hydrogen atom of the benzene ring bonded to the NH ₂ group may be replaced with a monovalent group.)

By making A in the above formula (d _AL ) have the above-mentioned form, the resistance to AC afterimages is improved, and when two types of polyamic acids are used, they are appropriately compatible with each other, thereby obtaining low pretilt angle characteristics.
In order to obtain high liquid crystal alignment properties, * ₁₁ is preferably a bond bonded to an oxygen atom.
In order to obtain low pretilt angle characteristics, n in the group * ₁₁ -(CH ₂ ) _n -O-* ₁₂ is preferably an integer of 1 to 4, more preferably an integer of 1 to 3, and even more preferably an integer of 1 or 2.
In the above formula (d _AL ), the two amino groups are preferably at the para-position relative to A, from the viewpoint of obtaining high liquid crystal alignment properties.
In order to suitably obtain the effects of the present invention, A in the above formula (d _AL ) is preferably a divalent organic group having 10 or less carbon atoms.
In the above formula (d _AL ), examples of the monovalent group 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 carboxy group, a hydroxy group, an alkyloxycarbonyl group having 1 to 10 carbon atoms, a cyano group, and a nitro group.

As the diamine represented by the above formula (d _AL ), diamines represented by the following formulae (d _AL -1) to (d _AL -9) are preferred, from the viewpoint of suitably achieving the effects of the present invention.

In the above formulae (d _AL -1) to (d _AL -2) and (d _AL -4) to (d _AL -5), n is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2, from the viewpoint of obtaining low pretilt angle characteristics.
In the formula (d _AL -3), m and n are each independently preferably 1 to 4, more preferably 1 to 3, and even more preferably 1 or 2, from the viewpoint of obtaining low pretilt angle characteristics.
In the above formula (d _AL -6), n is more preferably 1 to 3, and even more preferably 1 or 2. In the above formula (d _AL -6), m1 and m2 are each independently more preferably 1 to 3, and even more preferably 1 or 2. From the viewpoint of obtaining low pretilt angle characteristics, the sum of m1, m2 and n is preferably 10 or less.
In the above formulae (d _AL -7) and (d _AL -9), n is preferably 1 to 3, and more preferably 1 or 2, from the viewpoint of obtaining low pretilt angle characteristics.
In the above formula (d _AL -8), n is more preferably 1 to 4, further preferably 1 to 3, and still more preferably 1 or 2. In the above formula (d _AL -8), m1 and m2 are each independently more preferably 1 to 4, further preferably 1 to 3, and still more preferably 1 or 2. From the viewpoint of obtaining low pretilt angle characteristics, the sum of m1, m2, and n is preferably 10 or less.
In order to obtain high liquid crystal alignment properties, the two amino groups in the above formulae (d _AL -1) to (d _AL -9) are preferably at the para-position relative to the divalent organic group connecting the two benzene rings.

The content of the diamine represented by the formula (d _AL ) in the constituent components of the polyamic acid (A) is not particularly limited, but is preferably 10 mol % or more, more preferably 20 mol % or more, and even more preferably 50 mol % or more of the total diamine components used in the production of the polyamic acid (A). When other diamines described later are used in combination, the content of the diamine represented by the formula (d _AL ) is preferably 95 mol % or less, more preferably 90 mol % or less, and even more preferably 85 mol % or less.

The diamine component used in the production of the polyamic acid (A) contained in the liquid crystal aligning agent of the present invention can be various diamines (hereinafter also referred to as other diamines) in addition to the diamine represented by the above formula (d _AL ) depending on the desired properties of the liquid crystal aligning agent. As the other diamines, the following can be used. The diamines may be used alone or in combination of two or more.

Diamines represented by the above formula (d _n ), diamines represented by the following formula (O); diamines having a photoalignment group such as 4,4′-diaminoazobenzene or diaminotolane; diamines having an amide bond or a urea bond such as diamines represented by the following formulas (h-1) to (h-5); 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 1,2-bis(4-aminophenyl)ethane, 1,2-bis(3-aminophenyl)ethane, 1,3-bis(4-aminophenyl)propane, 1,3-bis(3-aminophenyl)propane, 1,4-bis(4-aminophenyl)propane, 1,4-bis(4-aminophenyl)butane, 1,4-bis(3-aminophenyl)butane, 1,5-bis(4-aminophenyl)butane, 1,5-bis(4-aminophenyl)pentane, 1,5-bis(3-aminophenyl)pentane, 1,6-bis(4-aminophenyl)hexane, 1,6-bis(3-aminophenyl)hexane, 4,4'-diaminobenzophenone, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenyl ₎ benzene, 1,4-bis(4-aminobenzyl)benzene, ), diamines represented by the formula (3b-1) to the formula (3b-4): 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol; diamines having a carboxy group such as 4,4'-diamino-3,3'-dihydroxybiphenyl, 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, 3,5-diaminobenzoic acid, and diamines represented by the following formulas (3b-1) to (3b-4); 4-(2-(methylamino)ethyl)aniline, 4-(2-aminoethyl)aniline, 1-(4-aminophenyl)-1,3,3-trimethyl-1H-indan-5-amine, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-inden-6-amine; methacrylic acid 2-(2,4-diamino diamines having a photopolymerizable group at the terminal, such as 2,4-diamino-N,N-diallylaniline and 2,4-diamino-N,N-bis(4-aminobenzoyloxy)ethyl; diamines having a steroid skeleton, such as cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, cholestanyl 3,5-diaminobenzoate, lanostannyl 3,5-diaminobenzoate, and 3,6-bis(4-aminobenzoyloxy)cholestane; diamines represented by the following formulae (V-1) to (V-6); diamines having a group "-N(D)-" (D represents a protecting group which is eliminated by heating and replaced with a hydrogen atom, preferably a tert-butoxycarbonyl group) such as those represented by the following formulae (5-1) to (5-9) (wherein D represents a protecting group which is eliminated by heating and replaced with a hydrogen atom, and is preferably a tert-butoxycarbonyl group), _n ); diamines having a siloxane bond such as 1,3-bis(3-aminopropyl)-tetramethyldisiloxane; metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-diaminocyclohexane, 4,4'-methylenebis(cyclohexylamine), diamines in which two amino groups are bonded to a group represented by any one of formulas (Y-1) to (Y-167) described in WO 2018/117239, and the like.
(p is an integer of 0 or 1. Ar represents a divalent benzene ring, a biphenyl structure, or a naphthalene ring. However, when p is 1, at least one Ar represents a biphenyl structure or a naphthalene ring, and in the above case, when one of the two Ars is a biphenyl structure, the other represents a biphenyl structure or a naphthalene ring. The two Ars may be the same or different, and any hydrogen atom in the ring in the Ar may be replaced with a monovalent group. _{Q 2} represents —(CH ₂ ) _n — (n is an integer of 2 to 18) or a group in which at least a portion of the —CH ₂ — in the —(CH ₂ ) _n — is replaced with any of —O—, —C(═O)—, and —O—C(═O)—. Specific examples of the monovalent group include the structures exemplified as the monovalent group in the above formula (d _AL ).)
Examples of formula (O) will be described later.
(When there are two or more m's, the two or more m's may be the same or different. One or more hydrogen atoms on the benzene ring may be substituted with a monovalent group.)
An example of formula (d ₀ ) will be given later.

In formula (3b-1), A ¹ represents a single bond, —CH ₂ —, —C ₂ H ₄ —, —C(CH ₃ ) ₂ —, —CF ₂ —, —C(CF ₃ ) ₂ —, —O—, —CO—, —NH—, —N(CH ₃ )—, —CONH—, —NHCO—, —CH ₂ O—, —OCH ₂ —, —COO—, —OCO—, —CON(CH ₃ )—, or —N(CH ₃ )CO—; m1 and m2 each independently represent an integer of 0 to 4; and m1+m2 represents an integer of 1 to 4.
In formula (3b-2), m3 and m4 each independently represent an integer of 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 of 1 to 5.
In formula (3b-4), A ³ and A ⁴ each independently represent a single bond, —CH ₂ —, —C ₂ H ₄ —, —C(CH ₃ ) ₂ —, —CF ₂ —, —C(CF ₃ ) ₂ —, —O—, —CO—, —NH—, —N(CH ₃ )—, —CONH—, —NHCO—, —CH ₂ O—, —OCH ₂ —, —COO—, —OCO—, —CON(CH ₃ )—, or —N(CH ₃ )CO—, and m6 is an integer of 1 to 4.

(In formulas (V-1) to (V-6), X ^v1 to X ^v4 and X ^p1 to X ^p2 each independently represent —(CH ₂ ) _a — (a is an integer of 1 to 15), —CONH—, —NHCO—, —CON(CH ₃ )—, —NH—, —O—, —CH ₂ O—, —CH ₂ OCO—, —COO—, or —OCO—; X ^v5 represents —O—, —CH ₂ O—, —CH ₂ OCO—, —COO—, or —OCO—; X _a represents a single bond, —O—, —NH—, or —O—(CH ₂ ) _m —O— (m is an integer of 1 to 6); R ^v1 to R ^v4 and R ^1a to R Each ^1b independently represents an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkoxyalkyl group having 2 to 20 carbon atoms. Two k's may be the same or different.
(In formulas (5-1) to (5-9), Boc represents a tert-butoxycarbonyl group.)

Specific examples of the monovalent group in the above formula (d _o ) include the structures exemplified as the monovalent group in the above formula (d _AL ).
As the diamine represented by the above formula (d _o ), diamines represented by the following formulas (d _o -1) to (d _o -6), 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether and 4,4′-diaminodiphenyl ether are preferred from the viewpoint of enhancing liquid crystal alignment properties.

In the diamine represented by the above formula (O), any hydrogen atom in the benzene ring, biphenyl structure, or naphthalene ring may be replaced with a monovalent group. Specific examples of the monovalent group include the structures exemplified as the monovalent group in the above formula (d _AL ).

As the diamine represented by the above formula (O), from the viewpoint of improving liquid crystal alignment, diamines represented by the following formulas (o-1) to (o-8) are preferred.

The tetracarboxylic acid derivative component used in the production of the polyamic acid (A) contained in the liquid crystal aligning agent of the present invention contains an aromatic tetracarboxylic acid dianhydride in an amount of 100 mol % of the total tetracarboxylic acid derivative component.
The aromatic tetracarboxylic acid dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxy groups, including at least one carboxy group bonded to an aromatic ring.
The aromatic tetracarboxylic dianhydride is preferably a tetracarboxylic dianhydride represented by the following formula (t _R ).
In the formula, X 1 _R is a structure selected from the following formulae (X _{1 R} -1) to (X _{1 R} -2).

In formulas ( _XR -1) to ( _XR -2), j and k are integers of 0 or 1, and _A1 and _A2 each independently represent a single bond, -O-, -CO-, -COO-, a phenylene group, a sulfonyl group, or an amide group. Multiple _A2s may be the same or different. * represents a bond.

Preferred specific examples of the above formulae (X _R -1) and (X _R -2) include the following formulae (X _R -3) to (X _R -18), where * has the same meaning as above.

From the viewpoint of improving the liquid crystal alignment property, the X 2 _R is preferably (X 2 _R -3) to (X 2 _R -10), more preferably (X 2 _R -3), (X _{2 R} -6) to (X 2 _R -8), and (X 2 _R -10).

<Polyamic Acid (B)>
The diamine component used in the production of the polyamic acid (B) contained in the liquid crystal aligning agent of the present invention contains a diamine represented by the above formula (d _AL ) and a diamine represented by the above formula (d _n ). The diamine represented by the above formula (d _AL ) and the diamine represented by the above formula (d _n ) may each be used alone or in combination of two or more.

The preferred embodiments of the diamine represented by the formula (d _AL ) used in the production of the polyamic acid (B) are the same as the preferred embodiments of the diamine represented by the formula (d _AL ) used in the production of the polyamic acid (A).
The content of the diamine represented by the formula (d _AL ) in the constituent components of the polyamic acid (B) is not particularly limited, but is preferably 5 to 80 mol %, more preferably 10 to 70 mol %, and even more preferably 40 to 60 mol %, of all diamine components used in the synthesis of the polyamic acid (B).

Examples of the nitrogen atom-containing heterocycle in the above formula (d _n ) include a pyrrole ring, imidazole ring, pyrazole ring, triazole ring, pyridine ring, pyrimidine ring, pyridazine ring, pyrazine ring, indole ring, benzimidazole ring, purine ring, quinoline ring, isoquinoline ring, naphthyridine ring, quinoxaline ring, phthalazine ring, triazine ring, carbazole ring, acridine ring, piperidine ring, piperazine ring, pyrrolidine ring, hexamethyleneimine ring, etc. Among these, a pyridine ring, pyrimidine ring, pyrazine ring, piperidine ring, piperazine ring, quinoline ring, carbazole ring, or acridine ring is preferred.

Examples of the monovalent organic group represented by R in the above formula (d _n ) include alkyl groups such as methyl, ethyl, and propyl; alkenyl groups such as vinyl; cycloalkyl groups such as cyclohexyl; aryl groups such as phenyl and methylphenyl; and alkoxy groups (e.g., methoxy and ethoxy). R is preferably a hydrogen atom or a methyl group.

Specific examples of the diamine represented by the above formula (d _n ) include 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, 1,4-bis-(4-aminophenyl)-piperazine, 3,6-diaminoacridine, N-ethyl-3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, and diamines represented by the following formulae (d _n -1) to (d _n -3):

In formula (d _n -1), m1 and m1' each independently represent an integer of 1 or 2. n1 represents an integer of 1 to 3. R ₁ has the same meaning as R in the amino group represented by the above formula "* ₂₁ -NR-* ₂₂ ".
When a plurality of R _{1 s} and m1 's are present, the plurality of R 1 s and m1 's may be the same or different.

In formula (d _n -2), X ₂ represents a monovalent nitrogen-containing heterocyclic group, and specific examples of the nitrogen-containing heterocycle in the monovalent nitrogen-containing heterocyclic group include the structures exemplified for the nitrogen-containing heterocycle in formula (d _n ) above.
n1 is an integer of 1 or 2, and n2 is an integer that satisfies n1+n2=2. _{L 1} and L ₂ each independently represent a single bond, -CO-, an alkylene group having 1 to 6 carbon atoms, or a divalent organic group in which -O- or -CO- is inserted between the carbon-carbon bonds or at the terminal of the alkylene group, and which is bonded to the nitrogen atom via a carbon atom. R represents a hydrogen atom or a methyl group.
When a plurality of X _{2 ,} L ₂ , and R are present, the plurality of X _{2 ,} L ₂ , and R may be the same or different.

In formula (d _n -3), X ₃ represents a divalent group having a nitrogen atom-containing heterocycle, and specific examples of the nitrogen atom-containing heterocycle include the structures exemplified for the nitrogen atom-containing heterocycle in formula (d _n ) above.
_Ar3 represents a divalent aromatic ring group or a divalent saturated nitrogen atom-containing heterocyclic group. Specific examples of the aromatic ring in the divalent aromatic ring group include a benzene ring, a naphthalene ring, an anthracene ring, a pyridine ring, a pyrimidine ring, a pyrazine ring, a pyridazine ring, a triazine ring, a pyrrole ring, an imidazole ring, a pyrazole ring, a quinoline ring, an isoquinoline ring, a carbazole ring, a benzimidazole ring, an indole ring, a quinoxaline ring, and an acridine ring. Specific examples of the saturated nitrogen atom-containing heterocyclic ring in the divalent saturated nitrogen atom-containing heterocyclic group include a piperidine ring and a piperazine ring. Any hydrogen atom in the aromatic ring group and the saturated nitrogen atom-containing heterocyclic group may be replaced with a monovalent group. Examples of the monovalent group include the structures exemplified as the monovalent group in the above formula (d _AL ).
_L3 represents a single bond, —(CH ₂ ) _n — (n is an integer of 1 to 6), —NR′—, —(CH ₂ ) _n —NR′- (n is an integer of 1 to 6), —O—, —NR′-CO—, —CO-NR′-, —O—CO—, or —CO—O—, and R′ represents a hydrogen atom, a methyl group, or a tert-butoxycarbonyl group.
m3 and m3' each independently represents an integer of 0 to 2, and either m3 or m3' represents an integer of 1 or more.
When a plurality of Ar _3s and L _3s are present, the plurality of Ar _3s and L _3s may be the same or different.
In addition, each of the NH ₂ groups in formula (d _n -3) is bonded to a carbon atom constituting an aromatic ring.

Preferred specific examples of the diamines represented by the above formulas (d _n -1) to (d _n -3) include diamines represented by the following formulas (Dp-1) to (Dp-6) and diamines represented by the following formulas (z-1) to (z-14).

(Boc represents a tert-butoxycarbonyl group.)

The content of the diamine represented by the formula (d _n ) in the constituent components of the polyamic acid (B) is not particularly limited, but is preferably 20 to 95 mol %, more preferably 30 to 90 mol %, and even more preferably 40 to 60 mol % of the total diamine components used in the production of the polyamic acid (B).

In addition to the above-mentioned diamines, various diamines (hereinafter also referred to as other diamines (b)) can be used as the diamine component used in the production of the polyamic acid (B) contained in the liquid crystal aligning agent of the present invention, depending on the desired properties of the liquid crystal aligning agent.

Examples of the other diamines (b) include the compounds exemplified as the diamines used in the production of the polyamic acid (A) above. The other diamines (b) may be used singly or in combination of two or more.

The tetracarboxylic acid derivative component used in the production of the polyamic acid (B) contained in the liquid crystal aligning agent of the present invention contains at least one tetracarboxylic acid dianhydride selected from the group consisting of acyclic aliphatic tetracarboxylic acid dianhydrides and alicyclic tetracarboxylic acid dianhydrides in an amount of 5 mol % or more of the total tetracarboxylic acid derivative component.
From the viewpoint of obtaining the effects of the present invention, the total amount of the acyclic aliphatic tetracarboxylic acid dianhydride and the alicyclic tetracarboxylic acid dianhydride is more preferably 10 mol % or more, and even more preferably 20 mol % or more, of the total tetracarboxylic acid derivative components used in the production of the polyamic acid (B).
Here, the acyclic aliphatic tetracarboxylic acid dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxy groups bonded to a chain hydrocarbon structure. However, it does not need to be composed of only a chain hydrocarbon structure, and it may have an alicyclic structure or an aromatic ring structure as part of it. The alicyclic tetracarboxylic acid dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxy groups, including at least one carboxy group bonded to the alicyclic structure. However, none of these four carboxy groups is bonded to an aromatic ring. Furthermore, it does not need to be composed of only an alicyclic structure, and it may have a chain hydrocarbon structure or an aromatic ring structure as part of it. The above acyclic aliphatic tetracarboxylic acid dianhydrides and alicyclic tetracarboxylic acid dianhydrides may be used alone or in combination of two or more.
By using an acyclic aliphatic tetracarboxylic dianhydride and an alicyclic tetracarboxylic dianhydride, a polyamic acid (B) having a composition different from that of the polyamic acid (A) can be obtained. By employing two different types of polyamic acids in the liquid crystal aligning agent of the present invention, it is believed that the two types of polyamic acids are appropriately compatible with each other, making it possible to achieve both high resistance to AC image sticking and low pretilt angle characteristics.

From the viewpoint of highly enhancing the liquid crystal alignment properties, the acyclic aliphatic tetracarboxylic acid dianhydride and alicyclic tetracarboxylic acid dianhydride in component (B) are preferably tetracarboxylic acid dianhydrides having at least one partial structure selected from the group consisting of a cyclobutane ring structure, a cyclopentane ring structure, and a cyclohexane ring structure.

The acyclic aliphatic tetracarboxylic acid dianhydride or alicyclic tetracarboxylic acid dianhydride is preferably a tetracarboxylic acid dianhydride represented by the following formula (t):

In the formula, _X1 is a structure selected from the following formulae (X1-1) to (X1-23).

In formulas (X1-1) to (X1-4), R ₁ to R ₂₁ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms and containing a fluorine atom, or a phenyl group. * represents a bond. From the viewpoint of improving liquid crystal alignment, R ₁ to R ₂₁ are preferably a hydrogen atom, a halogen atom, a methyl group, or an ethyl group, and more preferably a hydrogen atom or a methyl group.

Specific examples of formula (X1-1) include the following formulas (1-1) to (1-6). From the viewpoint of improving liquid crystal alignment, formula (1-1) is particularly preferred. * has the same meaning as above.

From the viewpoint of enhancing liquid crystal alignment properties, _X1 in the above formula (t) is preferably the above formulae (X1-1) to (X1-10), (X1-18) to (X1-23), more preferably the above formulae (X1-1) to (X1-2), (X1-5), (X1-7) to (X1-10), (X1-21) or (X1-23), and still more preferably the above formulae (1-1), (1-2), (X1-2) or (X1-7) to (X1-10).

The tetracarboxylic acid derivative component used in the production of the polyamic acid (B) contained in the liquid crystal aligning agent of the present invention may be an aromatic tetracarboxylic acid dianhydride or a tetracarboxylic acid dianhydride other than these (collectively referred to as "other tetracarboxylic acid dianhydrides (b)") in addition to the acyclic aliphatic tetracarboxylic acid dianhydrides and alicyclic tetracarboxylic acid dianhydrides described above, depending on the desired properties of the liquid crystal aligning agent. Specific preferred examples of the aromatic tetracarboxylic acid dianhydride used in the production of the polyamic acid (B) are the same as those used in the production of the polyamic acid (A) described above.

When the tetracarboxylic acid derivative component used in the production of the polyamic acid (B) contained in the liquid crystal aligning agent of the present invention contains another tetracarboxylic acid dianhydride (b), the content of the other tetracarboxylic acid dianhydride (b) is preferably 5 to 95 mol%, more preferably 10 to 90 mol%, and even more preferably 20 to 80 mol%, of the total tetracarboxylic acid derivative components used in the production of the polyamic acid (B). In this case, the total amount of the acyclic aliphatic tetracarboxylic acid dianhydride and alicyclic tetracarboxylic acid dianhydride is preferably 5 to 95 mol%, more preferably 10 to 90 mol%, and even more preferably 20 to 80 mol%, of the total tetracarboxylic acid derivative components.

From the viewpoint of obtaining the effects of the present invention, the content ratio of the above-mentioned (A) component and (B) component may be, in mass ratio [(A) component]/[(B) component], 10/90 to 90/10, 20/80 to 90/10, or 20/80 to 80/20.

<Production of Polyamic Acid (A) and Polyamic Acid (B)>
The polyamic acid can be produced, for example, by the following method: Specifically, the polyamic acid can be synthesized by reacting a tetracarboxylic acid derivative component containing the above-mentioned tetracarboxylic acid dianhydride with a diamine component containing the above-mentioned diamine in the presence of an organic solvent at −20 to 150° C., preferably 0 to 50° C., for 30 minutes to 24 hours, preferably 1 to 12 hours (polycondensation).
Specific examples of organic solvents used in the above reaction include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and 1,3-dimethyl-2-imidazolidinone. Furthermore, 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. These solvents may be used in combination of two or more.

(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.)
The reaction can be carried out at any concentration, preferably 1 to 50% by mass, and more preferably 5 to 30% by mass. The reaction can be carried out at a high concentration initially, with additional solvent added later. In the reaction, the ratio of the total number of moles of the diamine components to the total number of moles of the tetracarboxylic acid components is preferably 0.8 to 1.2. As with a typical polycondensation reaction, the closer this molar ratio is to 1.0, the higher the molecular weight of the polyamic acid produced.

The polyamic acid obtained by the above reaction can be precipitated and recovered by pouring the reaction solution into a poor solvent while stirring it thoroughly. Alternatively, the precipitation can be repeated several times, washed with a poor solvent, and then dried at room temperature or by heating to obtain a purified polyamic acid powder. The poor solvent is not particularly limited, but examples include water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

[End-capping agent]
In synthesizing the polyamic acids (A) and (B) of the present invention, a terminal-capped polymer may be synthesized using a tetracarboxylic acid derivative component containing a tetracarboxylic acid dianhydride, a diamine component, and an appropriate terminal-capping agent.

Examples of end-capping agents include acid monoanhydrides such as acetic anhydride, maleic anhydride, nadic 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, and 4-ethynylphthalic anhydride; dicarbonate diester compounds such as di-tert-butyl dicarbonate and diallyl dicarbonate; chlorocarbonyl compounds such as acryloyl chloride, methacryloyl chloride, and nicotinic acid chloride; aniline, 2-aminophenol, 3-aminophenol, 4- Examples of the monoamine compounds include 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 isocyanates having an unsaturated bond, such as ethyl isocyanate, phenyl isocyanate, naphthyl isocyanate, 2-acryloyloxyethyl isocyanate, and 2-methacryloyloxyethyl isocyanate; and isothiocyanate compounds such as ethyl isothiocyanate and allyl isothiocyanate.

The proportion of end-capping agent used is preferably 20 molar parts or less, and more preferably 10 molar parts or less, per 100 molar parts of the total of the diamine component used and the organic diol component used if necessary.

When recovering the polyamic acid produced from a polyamic acid reaction solution, the reaction solution may be precipitated by pouring it into a solvent. Examples of solvents used for precipitation include methanol, ethanol, isopropyl alcohol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, toluene, benzene, and water. The polyamic acid precipitated by pouring it into a solvent can be recovered by filtration and then dried at room temperature or by heating under atmospheric or reduced pressure. Furthermore, the precipitated polymer can be redissolved in an organic solvent and reprecipitated and recovered 2 to 10 times to reduce the amount of impurities in the polymer. Examples of solvents that can be used in this process include alcohols, ketones, and hydrocarbons. Using three or more solvents selected from these is preferred, as it further increases the efficiency of purification.

The molecular weight of the polyamic acid (A) and polyamic acid (B) used in the present invention is preferably a weight-average molecular weight of 5,000 to 1,000,000, more preferably 10,000 to 150,000, measured by GPC (Gel Permeation Chromatography), taking into consideration the strength of the liquid crystal alignment film obtained therefrom, workability during film formation, and coating properties.

The liquid crystal aligning agent of the present invention may contain a polymer other than the polyamic acid (A) and the polyamic acid (B). Specific examples of the other polymer include a polymer selected from the group consisting of polyamic acid esters, polyimides, polysiloxanes, polyesters, polyamides, polyureas, polyurethanes, polyorganosiloxanes, cellulose derivatives, polyacetals, polystyrene derivatives, poly(styrene-maleic anhydride) copolymers, poly(isobutylene-maleic anhydride) copolymers, poly(vinyl ether-maleic anhydride) copolymers, poly(styrene-phenylmaleimide) derivatives, and poly(meth)acrylates. Specific examples of poly(styrene-maleic anhydride) copolymers include SMA1000, 2000, and 3000 (manufactured by Cray Valley) and GSM301 (manufactured by Gifu Shellac Co., Ltd.), a specific example of poly(isobutylene-maleic anhydride) copolymers includes ISOBAN-600 (manufactured by Kuraray), and a specific example of poly(vinyl ether-maleic anhydride) copolymers includes GANTREZ AN-139 (methyl vinyl ether maleic anhydride resin, manufactured by ISP Japan).
The content of the other polymers is preferably 90 parts by mass or less, more preferably 10 to 90 parts by mass, and even more preferably 20 to 80 parts by mass, relative to 100 parts by mass of the total of the polymers contained in the liquid crystal aligning agent.

The liquid crystal aligning agent according to the present invention is preferably a liquid composition in which the polyamic acid (A) and polyamic acid (B) are dissolved or dispersed in an organic solvent. Specifically, the organic solvent contained in the liquid crystal aligning agent is not particularly limited as long as it can uniformly dissolve the polyamic acid, but examples thereof include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyllactamide, N,N-dimethylpropionamide, tetramethylurea, N,N-diethylformamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, γ-valerolactone, 1,3-dimethyl-2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclohexane, cyclohexane-1,2-dimethyl-2-propanol ... Examples of good solvents include pentanone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, N-(n-propyl)-2-pyrrolidone, N-isopropyl-2-pyrrolidone, N-(n-butyl)-2-pyrrolidone, N-(t-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 these, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, and γ-butyrolactone are preferred. The content of the good solvent is preferably 20 to 99% by mass, more preferably 20 to 90% by mass, and particularly preferably 30 to 80% by mass of the total solvent contained in the liquid crystal aligning agent.

The organic solvent contained in the liquid crystal aligning agent is preferably a mixed solvent that combines the above-mentioned solvent with a solvent (also called a poor solvent) that improves the coatability and surface smoothness of the coating film when applying the liquid crystal aligning agent. Specific examples of poor solvents to be used in combination are listed below, but are not limited to these. The content of the poor solvent is preferably 1 to 80% by mass, more preferably 10 to 80% by mass, and particularly preferably 20 to 70% by mass, of the total solvent contained in the liquid crystal aligning agent. The type and content of the poor solvent are selected appropriately depending on the application device, application conditions, application environment, etc. of the liquid crystal aligning agent.

Examples of poor solvents include diisopropyl ether, diisobutyl ether, diisobutyl carbinol (2,6-dimethyl-4-heptanol), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, 1-(2-butoxyethoxy)-2-propanol, 2-(2-butoxy)-2-propanol, (2-ethoxyethoxy)-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 monopropyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, di Examples of suitable alkyl acrylates include ethylene glycol acetate, propylene glycol diacetate, n-butyl acetate, propylene glycol monoethyl ether acetate, cyclohexyl acetate, 4-methyl-2-pentyl 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, and diisobutyl ketone (2,6-dimethyl-4-heptanone).

Of these, 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 are preferred.

Preferred solvent combinations of good and poor solvents include N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone and propylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone, N-ethyl-2-pyrrolidone and propylene glycol diacetate, N,N-dimethyl lactamide and diisobutyl ketone, and N-methyl-2-pyrrolidone. N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate, N-methyl-2-pyrrolidone and ethyl 3-ethoxypropionate, dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and ethyl 3-ethoxypropionate and diethylene glycol monopropyl ether, N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate and diethylene glycol monopropyl ether, N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether acetate, 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-ethyl-2-pyrrolidone and diethylene glycol monoethyl ether and butyl cellosolve acetate, N-methyl-2-pyrrolidone and diethylene glycol monomethyl ether and butyl cellosolve acetate, N,N-dimethyl lactamide and diethylene glycol diethyl ether, N-methyl-2-pyrrolidone and gamma -butyrolactone, 4-hydroxy-4-methyl-2-pentanone, and diethylene glycol diethyl ether, N-ethyl-2-pyrrolidone, N-methyl-2-pyrrolidone, and 4-hydroxy-4-methyl-2-pentanone, N-ethyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and diisobutyl ketone, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and dipropylene glycol monomethyl ether, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and dipropylene glycol monomethyl ether ethyl-2-pentanone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone and propylene glycol diacetate, N-ethyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone and dipropylene glycol dimethyl ether, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and diisobutyl ketone, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and propylene glycol diacetate, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether and diisobutyl ketone , N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisopropyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisobutylcarbinol, N-methyl-2-pyrrolidone, γ-butyrolactone, and dipropylene glycol dimethyl ether, N-methyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol dimethyl ether, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone and diethyl ethylene glycol diethyl ether and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether and propylene glycol diacetate, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether and diisobutyl ketone, N-ethyl-2-pyrrolidone, γ-butyrolactone and diisobutyl ketone, N-ethyl-2-pyrrolidone, N,N-dimethyl lactamide and diisobutyl ketone, N-methyl-2-pyrrolidone, ethylene glycol monobutyl ether and ethylene glycol monobutyl ether acetate, γ-butyrolactone and ethylene glycol monobutyl Examples of suitable mixtures include ethylene glycol monobutyl ether acetate and dipropylene glycol dimethyl ether, N-ethyl-2-pyrrolidone, ethylene glycol monobutyl ether acetate and propylene glycol dimethyl ether, N-methyl-2-pyrrolidone, 4-methyl-2-pentyl acetate and ethylene glycol monobutyl ether, N-ethyl-2-pyrrolidone, cyclohexyl acetate, diacetone alcohol, cyclohexanone and propylene glycol monomethyl ether, cyclopentanone and propylene glycol monomethyl ether, and N-methyl-2-pyrrolidone, cyclohexanone and propylene glycol monomethyl ether.

(Liquid crystal alignment agent)
The liquid crystal aligning agent of the present invention may additionally contain a component (hereinafter also referred to as an additive component) other than the above-mentioned component (A), component (B), and organic solvent. Examples of such additive components include at least one crosslinking compound selected from the group consisting of a crosslinking compound having at least one substituent selected from an epoxy group, an isocyanate group, an oxetane group, a cyclocarbonate group, a blocked isocyanate group, a hydroxy group, and an alkoxy group, and a crosslinking compound having a polymerizable unsaturated group, a functional silane compound, a metal chelate compound, a curing accelerator, a surfactant, an antioxidant, a sensitizer, a preservative, and a compound for adjusting the dielectric constant or electrical resistance of a resin film.

Preferred specific examples of the crosslinkable compound include compounds represented by any one of the following formulas (CL-1) to (CL-11).

Examples of compounds for adjusting the dielectric constant and electrical resistance of the resin film include monoamines having a nitrogen-containing aromatic heterocycle, such as 3-picolylamine. When using a monoamine having a nitrogen-containing aromatic heterocycle, its content is preferably 0.1 to 30 parts by mass, and more preferably 0.1 to 20 parts by mass, per 100 parts by mass of the polymer component contained in the liquid crystal alignment agent.

Specific preferred examples of functional silane compounds include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-glycidoxypropylmethyldimethoxysilane. , 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, tris(3-trimethoxysilylpropyl)isocyanurate, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, etc. When a functional silane compound is used, the content thereof is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, per 100 parts by mass of the polymer component contained in the liquid crystal alignment agent.

The solids concentration in the liquid crystal alignment agent (the proportion of the total mass of the components other than the solvent in the liquid crystal alignment agent to the total mass of the liquid crystal alignment agent) is selected appropriately taking into account viscosity, volatility, etc., but is preferably in the range of 1 to 10% by mass.

The particularly preferred range of solid content varies depending on the method used to apply the liquid crystal alignment agent to the substrate. For example, when using a spin coating method, a solid content range of 1.5 to 4.5% by mass is particularly preferred. When using a printing method, a solid content range of 3 to 9% by mass is particularly preferred, thereby resulting in a solution viscosity range of 12 to 50 mPa·s. When using an inkjet method, a solid content range of 1 to 5% by mass is particularly preferred, thereby resulting in a solution viscosity range of 3 to 15 mPa·s. The temperature when preparing the polymer composition is preferably 10 to 50°C, more preferably 20 to 30°C.

The liquid crystal alignment agent described above can be effectively applied to various technical applications, such as liquid crystal alignment films (liquid crystal alignment films for retardation films, liquid crystal alignment films for scanning antennas and liquid crystal array antennas, or liquid crystal alignment films for transmissive/scattering liquid crystal dimming elements), protective films (e.g., protective films for color filters), spacer films, interlayer insulating films, anti-reflection films, wiring coating films, antistatic films, motor insulating films (gate insulating films for flexible displays), etc.

[Liquid crystal alignment film and liquid crystal display element]
A liquid crystal alignment film can be produced by using the liquid crystal aligning agent. A liquid crystal display element according to the present invention includes a liquid crystal alignment film formed using the liquid crystal aligning agent. The operation mode of the liquid crystal display element according to the present invention is not particularly limited, and the element can be applied to various operation modes, such as TN type, STN (Super Twisted Nematic) type, vertical alignment type (including VA-MVA type, VA-PVA type, etc.), in-plane switching type (IPS type, FFS type), and optically compensated bend type (OCB type).

The liquid crystal display device of the present invention includes, for example, the following steps (1) to (3).
The liquid crystal display element of the present invention can be produced, for example, by a method including the following steps (1) to (4), a method including steps (1) to (2) and (4), a method including steps (1) to (3), (4-2) and (4-4), or a method including steps (1) to (3), (4-3) and (4-4).

<Step (1): Step of applying liquid crystal alignment agent onto substrate>
The step (1) is a step of applying the liquid crystal aligning agent of the present invention onto a substrate. Specific examples of the step (1) are as follows.
The liquid crystal aligning agent of the present invention is applied to one side of a substrate having a patterned transparent conductive film by an appropriate application method, such as a roll coater method, a spin coat method, a printing method, or an inkjet method. The substrate is not particularly limited as long as it is highly transparent, and plastic substrates such as acrylic substrates and polycarbonate substrates can be used in addition to glass substrates and silicon nitride substrates. In addition, in a reflective liquid crystal display element, an opaque material such as a silicon wafer can be used for only one substrate, and in this case, a light-reflecting material such as aluminum can also be used for the electrode. Furthermore, when manufacturing an IPS or FFS liquid crystal display element, a substrate having an electrode made of a comb-shaped patterned transparent conductive film or metal film and an opposing substrate having no electrode are used.

Methods for applying the liquid crystal alignment agent to a substrate and forming a film include screen printing, offset printing, flexographic printing, inkjet printing, and spray printing. Among these, application and film formation using the inkjet method are preferred.

<Step (2): Step of baking the applied liquid crystal alignment agent to obtain a film>
In the step (2), the liquid crystal alignment agent applied to the substrate is baked to obtain a film. Specific examples of the step (2) are as follows.
After applying the liquid crystal aligning agent to the substrate in step (1), the solvent can be evaporated or the polyamic acid can be thermally imidized using a heating means such as a hot plate, a heat circulation oven, or an IR (infrared) oven. The drying and baking steps after applying the liquid crystal aligning agent of the present invention can be performed at any temperature and for any time, and may be performed multiple times. The temperature at which the liquid crystal aligning agent is baked can be, for example, 40 to 180°C. To shorten the process, the baking can be performed at 40 to 150°C. The baking time is not particularly limited, but examples include 1 to 10 minutes or 1 to 5 minutes. When thermally imidizing the polyamic acid, a baking step at a temperature range of, for example, 150 to 300°C or 150 to 250°C may be added after the above step. The baking time is not particularly limited, but examples include 5 to 40 minutes or 5 to 30 minutes.
If the film-like material after baking is too thin, the reliability of the liquid crystal display device may decrease, so the film thickness is preferably 5 to 300 nm, more preferably 10 to 200 nm.

<Step (3): Step of subjecting the film obtained in step (2) to alignment treatment>
Step (3) is a step of optionally performing an alignment treatment on the film obtained in step (2). That is, in horizontal alignment type liquid crystal display devices such as IPS mode or FFS mode, the coating film is subjected to an alignment ability imparting treatment. On the other hand, in vertical alignment type liquid crystal display devices such as VA mode or PSA mode, the formed coating film can be used as a liquid crystal alignment film as is, but the coating film may also be subjected to an alignment ability imparting treatment. Alignment treatment methods for liquid crystal alignment films include rubbing treatment and photo-alignment treatment. Photo-alignment treatment methods include irradiating the surface of the film-like material with radiation polarized in a certain direction, and optionally performing a heat treatment at a temperature preferably of 150 to 250°C to impart liquid crystal alignment (also referred to as liquid crystal alignment ability). As the radiation, ultraviolet light or visible light having a wavelength of 100 to 800 nm can be used. Among these, ultraviolet light having a wavelength of 100 to 400 nm is preferred, and more preferably 200 to 400 nm is more preferred.

The radiation dose is preferably 1 to 10,000 mJ/ ^cm² . Of these, 100 to 5,000 mJ/ ^cm² is more preferred. When irradiating with radiation, the substrate having the film-like material may be irradiated while being heated at 50 to 250°C in order to improve the liquid crystal alignment. The liquid crystal alignment film produced in this manner can stably align liquid crystal molecules in a fixed direction.
Furthermore, the liquid crystal alignment film irradiated with polarized radiation by the above method can be contact-treated with water or a solvent, or the liquid crystal alignment film irradiated with radiation can be heat-treated.

The solvent used in the contact treatment is not particularly limited, as long as it dissolves the decomposition products produced from the film-like material by irradiation. Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, and cyclohexyl acetate. One type of solvent may be used, or two or more types may be used in combination.

The temperature for the heat treatment of the coating film irradiated with the above radiation is preferably 50 to 300°C, and even more preferably 120 to 250°C. The heat treatment time is preferably 1 to 30 minutes.

<Step (4): Step of Producing Liquid Crystal Cell>
In step (4), two substrates on which the liquid crystal alignment film is formed as described above are prepared, and liquid crystal is disposed between the two substrates arranged opposite to each other. Specifically, the following two methods can be mentioned.
In the first method, two substrates are placed opposite each other with a gap (cell gap) between them so that their liquid crystal alignment films face each other, and then the peripheries of the two substrates are bonded together using a sealant. A liquid crystal composition is injected into the substrate surfaces and the cell gap defined by the sealant so that it comes into contact with the film surface, and the injection hole is then sealed.

The second method is called the ODF (One Drop Fill) method. For example, a UV-curable sealant is applied to a predetermined location on one of two substrates on which a liquid crystal alignment film has been formed, and a liquid crystal composition is then dropped onto several predetermined locations on the liquid crystal alignment film surface. The other substrate is then attached so that the liquid crystal alignment film faces the other substrate, and the liquid crystal composition is spread over the entire surface of the substrate and brought into contact with the film surface. Next, the entire surface of the substrate is irradiated with UV light to cure the sealant. In either method, it is desirable to further heat the substrate to a temperature at which the liquid crystal composition is in an isotropic phase, and then slowly cool it to room temperature to remove flow alignment that occurs during liquid crystal filling.
When the coating films are subjected to rubbing treatment, the two substrates are placed opposite each other so that the rubbing directions of the coating films are at a predetermined angle, for example, perpendicular or anti-parallel to each other.
As the sealing agent, for example, an epoxy resin containing a hardener and aluminum oxide spheres as spacers can be used.

The liquid crystal composition is not particularly limited, and may be any of various liquid crystal compositions containing at least one liquid crystal compound (liquid crystal molecule) and having positive or negative dielectric anisotropy. Hereinafter, a liquid crystal composition having positive dielectric anisotropy will be referred to as a positive liquid crystal, and a liquid crystal composition having negative dielectric anisotropy will be referred to as a negative liquid crystal.
The liquid crystal composition may contain a liquid crystal compound having a fluorine atom, a hydroxy group, an amino group, a fluorine atom-containing group (e.g., a trifluoromethyl group), a cyano group, an alkyl group, an alkoxy group, an alkenyl group, an isothiocyanate group, a heterocycle, a cycloalkane, a cycloalkene, a steroid skeleton, a benzene ring, or a naphthalene ring, or may contain a compound having two or more rigid moieties (mesogenic skeletons) exhibiting liquid crystal properties in the molecule (e.g., a bimesogenic compound in which two rigid biphenyl structures or terphenyl structures are connected by an alkyl group). Examples of the liquid crystal composition include a liquid crystal composition exhibiting a nematic phase, a liquid crystal composition exhibiting a smectic phase, and a liquid crystal composition exhibiting a cholesteric phase. Among these, a liquid crystal composition exhibiting a nematic phase is preferred.
Furthermore, the liquid crystal composition may further contain additives from the viewpoint of improving the liquid crystal alignment property, such as photopolymerizable monomers such as compounds having a polymerizable group, optically active compounds (e.g., S-811 manufactured by Merck Ltd.), antioxidants, ultraviolet absorbers, dyes, antifoaming agents, polymerization initiators, or polymerization inhibitors.
Examples of the positive liquid crystal include ZLI-2293, ZLI-4792, MLC-2003, MLC-2041, MLC-3019, and MLC-7081 manufactured by Merck.
Examples of negative liquid crystals include MLC-6608, MLC-6609, MLC-6610, and MLC-7026-100 manufactured by Merck.
As a liquid crystal composition used in a PSA type liquid crystal display element described later, MLC-3023 manufactured by Merck Ltd. is an example of a liquid crystal containing a polymerizable compound.
The liquid crystal aligning agent of the present invention is preferably used for positive liquid crystals from the viewpoint of suitably obtaining the effects of the present invention.

The liquid crystal aligning agent of the present invention is also preferably used for a liquid crystal display element (PSA type liquid crystal display element) which has a liquid crystal layer between a pair of substrates provided with electrodes, and is produced through a process of disposing a liquid crystal composition containing a polymerizable compound which is polymerized by at least one of active energy rays and heat between the pair of substrates, and polymerizing the polymerizable compound by at least one of irradiation with active energy rays and heating while applying a voltage between the electrodes.
The liquid crystal aligning agent of the present invention is also preferably used for a liquid crystal display element (SC-PVA mode liquid crystal display element) which has a liquid crystal layer between a pair of substrates provided with electrodes, and is produced through a process of disposing a liquid crystal alignment film containing a polymerizable group that is polymerized by at least one of active energy rays and heat between the pair of substrates, and applying a voltage between the electrodes.

<Step (4-2): In the case of a PSA type liquid crystal display element>
In the step (4-2), the liquid crystal composition containing a polymerizable compound is injected or dropped, and the other steps are the same as those in the step (4). Examples of the polymerizable compound include a polymerizable compound having one or more polymerizable unsaturated groups in the molecule, such as an acrylate group or a methacrylate group.

<Step (4-3): In the case of an SC-PVA mode liquid crystal display element>
Step (4-3) may involve a process similar to step (4) above, followed by a step of irradiating with ultraviolet light, as described below, to produce a liquid crystal display element. This process, similar to the production of the PSA-type liquid crystal display element, allows for the production of a liquid crystal display element with excellent response speed with a small amount of light irradiation. The compound having a polymerizable group may be a compound having one or more of the above-mentioned polymerizable unsaturated groups in its molecule, and its content is preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass, per 100 parts by mass of all polymer components. Furthermore, the polymerizable group may be contained in a polymer used in a liquid crystal aligning agent. Examples of such polymers include polymers obtained by reacting a diamine component containing a diamine having the above-mentioned photopolymerizable group at its terminal.

<Step (4-4): Step of irradiating with ultraviolet light>
In step (4-4), the liquid crystal cell is irradiated with light while a voltage is applied between the conductive films of the pair of substrates obtained in step (4-2) or step (4-3). The voltage applied here can be, for example, 5 to 50 V DC or AC. The irradiated light can be, for example, ultraviolet light and visible light containing light with a wavelength of 150 to 800 nm, but ultraviolet light containing light with a wavelength of 300 to 400 nm is preferred. Examples of light sources that can be used for the irradiated light include low-pressure mercury lamps, high-pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonance lamps, xenon lamps, and excimer lasers. The light irradiation dose is preferably 1,000 to 200,000 J/ ^m² , more preferably 1,000 to 100,000 J/ ^m² .

A liquid crystal display element can then be obtained by laminating a polarizing plate to the outer surface of the liquid crystal cell as needed. Examples of polarizing plates that can be laminated to the outer surface of a liquid crystal cell include polarizing plates in which a polarizing film called an "H film," made by stretching and aligning polyvinyl alcohol and absorbing iodine, is sandwiched between cellulose acetate protective films, or polarizing plates made of the H film itself.

A liquid crystal display element can then be obtained by laminating a polarizing plate to the outer surface of the liquid crystal cell as needed. Examples of polarizing plates that can be laminated to the outer surface of a liquid crystal cell include polarizing plates in which a polarizing film called an "H film," made by stretching and aligning polyvinyl alcohol and absorbing iodine, is sandwiched between cellulose acetate protective films, or polarizing plates made of the H film itself.

An IPS substrate, which is a comb-tooth electrode substrate used in IPS mode, has a base material, a plurality of linear electrodes formed on the base material and arranged in a comb-tooth pattern, and a liquid crystal alignment film formed on the base material so as to cover the linear electrodes.
The FFS substrate, which is a comb-tooth electrode substrate used in the FFS mode, has a base material, a surface electrode formed on the base material, an insulating film formed on the surface electrode, a plurality of linear electrodes formed on the insulating film and arranged in a comb-tooth pattern, and a liquid crystal alignment film formed on the insulating film so as to cover the linear electrodes.

FIG. 1 is a schematic cross-sectional view showing an example of an in-plane switching liquid crystal display element of the present invention, which is an example of an IPS mode liquid crystal display element.
In the IPS LCD element 1 illustrated in Fig. 1, liquid crystal 3 is sandwiched between a comb-shaped electrode substrate 2 having a liquid crystal alignment film 2c and a counter substrate 4 having a liquid crystal alignment film 4a. The comb-shaped electrode substrate 2 has a base material 2a, a plurality of linear electrodes 2b formed on the base material 2a and arranged in a comb-like pattern, and a liquid crystal alignment film 2c formed on the base material 2a so as to cover the linear electrodes 2b. The counter substrate 4 has a base material 4b and a liquid crystal alignment film 4a formed on the base material 4b. The liquid crystal alignment film 2c is, for example, the liquid crystal alignment film of the present invention. The liquid crystal alignment film 4c is also the liquid crystal alignment film of the present invention.
In this IPS LCD element 1, when a voltage is applied to the linear electrodes 2b, an electric field is generated between the linear electrodes 2b as indicated by electric force lines L.

FIG. 2 is a schematic cross-sectional view showing another example of the in-plane switching liquid crystal display element of the present invention, which is an example of an FFS mode liquid crystal display element.
In the IPS LCD element 1 illustrated in Figure 2, liquid crystal 3 is sandwiched between a comb-shaped electrode substrate 2 having a liquid crystal alignment film 2h and a counter substrate 4 having a liquid crystal alignment film 4a. The comb-shaped electrode substrate 2 has a base material 2d, a surface electrode 2e formed on the base material 2d, an insulating film 2f formed on the surface electrode 2e, a plurality of linear electrodes 2g formed on the insulating film 2f and arranged in a comb-like pattern, and a liquid crystal alignment film 2h formed on the insulating film 2f so as to cover the linear electrodes 2g. The counter substrate 4 has a base material 4b and a liquid crystal alignment film 4a formed on the base material 4b. The liquid crystal alignment film 2h is, for example, a liquid crystal alignment film of the present invention. The liquid crystal alignment film 4a is also a liquid crystal alignment film of the present invention.
In this IPS LCD element 1, when a voltage is applied to the surface electrodes 2e and the linear electrodes 2g, an electric field is generated between the surface electrodes 2e and the linear electrodes 2g as indicated by electric force lines L.

In addition to the above-mentioned uses, the liquid crystal alignment film of the present invention can be used for a variety of other purposes. For example, it can be used as a liquid crystal alignment film for retardation films, for scanning antennas and liquid crystal array antennas, or for transmissive/scattering liquid crystal dimming elements. It can also be used for purposes other than liquid crystal alignment films, such as protective films (e.g., protective films for color filters), spacer films, interlayer insulating films, anti-reflection films, wiring coating films, antistatic films, and motor insulating films (gate insulating films for flexible displays).

The liquid crystal display element of the present invention can be effectively applied to a variety of devices, such as watches, portable games, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, LCD televisions, and information displays.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The abbreviations for compounds and solvents are as follows.
NMP: N-methyl-2-pyrrolidone BCS: Butyl cellosolve CA-1 to CA-4: Compounds of the following structural formulas DA-1 to DA-6: Compounds of the following structural formulas AD-1: 3-glycidoxypropyltriethoxysilane AD-2: Compounds of the following structural formulas

<Synthesis of Polymer>
(Synthesis Example 1)
2.93 g (12.0 mmol) of DA-2 and 1.19 g (3.0 mmol) of DA-3 were weighed into a 100 mL recovery flask equipped with a stirrer and a nitrogen inlet tube, 30.2 g of NMP was added, and the mixture was dissolved by stirring while supplying nitrogen. While stirring this diamine solution under water cooling, 3.11 g (14.3 mmol) of CA-1 was added, and then 22.8 g of NMP was added, and the mixture was stirred at 50°C for 12 hours under a nitrogen atmosphere to obtain a polymer solution A-1 containing a polyamic acid.

(Synthesis Example 2)
In a 100 mL recovery flask equipped with a stirrer and a nitrogen inlet tube, 3.44 g (12.0 mmol) of DA-1 and 1.19 g (3.0 mmol) of DA-3 were weighed out, 33.9 g of NMP was added, and the mixture was dissolved by stirring while supplying nitrogen. While stirring this diamine solution under water cooling, 3.11 g (14.3 mmol) of CA-1 was added, and then 22.8 g of NMP was added, and the mixture was stirred under a nitrogen atmosphere at 50°C for 12 hours to obtain a polymer solution A-2 containing polyamic acid.

(Synthesis Example 3)
4.30 g (15.0 mmol) of DA-1 was weighed into a 100 mL recovery flask equipped with a stirrer and a nitrogen inlet tube, and 31.5 g of NMP was added. The mixture was stirred and dissolved under nitrogen flow. While stirring this diamine solution under water cooling, 3.11 g (14.3 mmol) of CA-1 was added, and then 22.8 g of NMP was added. The mixture was stirred at 50°C for 12 hours under a nitrogen atmosphere to obtain a polymer solution A-3 containing polyamic acid.

(Synthesis Example 4)
2.15 g (7.5 mmol) of DA-1, 1.10 g (4.5 mmol) of DA-2, and 1.19 g (3.0 mmol) of DA-3 were weighed into a 100 mL recovery flask equipped with a stirrer and a nitrogen inlet tube, and 32.5 g of NMP was added. The mixture was dissolved by stirring while supplying nitrogen. While stirring this diamine solution under water cooling, 3.11 g (14.3 mmol) of CA-1 was added, and then 22.8 g of NMP was added. The mixture was stirred under a nitrogen atmosphere at 50°C for 12 hours to obtain a polymer solution A-4 containing polyamic acid.

(Synthesis Example 5)
3.66 g (15.0 mmol) of DA-2 was weighed into a 100 mL recovery flask equipped with a stirrer and a nitrogen inlet tube, and 26.9 g of NMP was added. The mixture was stirred and dissolved under nitrogen flow. While stirring this diamine solution under water cooling, 3.11 g (14.3 mmol) of CA-1 was added, and then 22.8 g of NMP was added. The mixture was stirred at 50°C for 12 hours under a nitrogen atmosphere to obtain a polymer solution A-5 containing a polyamic acid.

(Synthesis Example 6)
Into a 100 mL recovery flask equipped with a stirrer and a nitrogen inlet tube, 2.81 g (11.5 mmol) of DA-2 and 2.29 g (11.5 mmol) of DA-4 were weighed out, 28.9 g of NMP was added, and the mixture was dissolved by stirring while supplying nitrogen. While stirring this diamine solution under water cooling, 0.95 g (4.8 mmol) of CA-2 was added, and 5.4 g of NMP was further added, and the mixture was stirred at 23 ° C. under a nitrogen atmosphere for 30 minutes. Thereafter, while stirring this solution under water cooling, 4.32 g (17.3 mmol) of CA-3 was added, and 24.5 g of NMP was further added, and the mixture was stirred under a nitrogen atmosphere at 50 ° C. for 12 hours to obtain a polymer solution B-1 containing polyamic acid.

(Synthesis Example 7)
Into a 100 mL recovery flask equipped with a stirrer and a nitrogen inlet tube, 2.44 g (10.0 mmol) of DA-2 and 1.99 g (10.0 mmol) of DA-4 were weighed out, 25.1 g of NMP was added, and the mixture was dissolved by stirring while supplying nitrogen. While stirring this diamine solution under water cooling, 3.75 g (15.0 mmol) of CA-3 was added, and then 21.3 g of NMP was added, and the mixture was stirred at 50 ° C. under a nitrogen atmosphere for 2 hours. Thereafter, while stirring this solution under water cooling, 1.25 g (4.3 mmol) of CA-4 was added, and then 7.1 g of NMP was added, and the mixture was stirred under a nitrogen atmosphere at 70 ° C. for 12 hours to obtain a polymer solution B-2 containing polyamic acid.

(Synthesis Example 8)
Into a 100 mL recovery flask equipped with a stirrer and a nitrogen inlet tube, 2.86 g (10.0 mmol) of DA-1 and 1.99 g (10.0 mmol) of DA-4 were weighed out, 27.5 g of NMP was added, and the mixture was dissolved by stirring while supplying nitrogen. While stirring this diamine solution under water cooling, 3.75 g (15.0 mmol) of CA-3 was added, and then 21.3 g of NMP was added, and the mixture was stirred at 50 ° C. under a nitrogen atmosphere for 2 hours. Thereafter, while stirring this solution under water cooling, 1.25 g (4.3 mmol) of CA-4 was added, and then 7.1 g of NMP was added, and the mixture was stirred under a nitrogen atmosphere at 70 ° C. for 12 hours to obtain a polymer solution B-3 containing polyamic acid.

(Synthesis Example 9)
Into a 100 mL recovery flask equipped with a stirrer and a nitrogen inlet tube, 3.67 g (18.4 mmol) of DA-4 and 0.91 g (4.6 mmol) of DA-5 were weighed out, 25.9 g of NMP was added, and the mixture was dissolved by stirring while supplying nitrogen. While stirring this diamine solution under water cooling, 0.91 g (4.6 mmol) of CA-2 was added, and 5.4 g of NMP was further added, and the mixture was stirred at 23 ° C. under a nitrogen atmosphere for 30 minutes. Thereafter, while stirring this solution under water cooling, 4.32 g (17.3 mmol) of CA-3 was added, and 24.5 g of NMP was further added, and the mixture was stirred under a nitrogen atmosphere at 50 ° C. for 12 hours to obtain a polymer solution C-1 containing polyamic acid.

(Synthesis Example 10)
Into a 100 mL recovery flask equipped with a stirrer and a nitrogen inlet tube, 2.29 g (11.5 mmol) of DA-4 and 2.28 g (11.5 mmol) of DA-5 were weighed out, 25.9 g of NMP was added, and the mixture was dissolved by stirring while supplying nitrogen. While stirring this diamine solution under water cooling, 0.95 g (4.8 mmol) of CA-2 was added, and then 5.4 g of NMP was added, and the mixture was stirred at 23 ° C. under a nitrogen atmosphere for 30 minutes. Thereafter, while stirring this solution under water cooling, 4.32 g (17.3 mmol) of CA-3 was added, and then 24.5 g of NMP was added, and the mixture was stirred under a nitrogen atmosphere at 50 ° C. for 12 hours to obtain a polymer solution C-2 containing polyamic acid.

(Synthesis Example 11)
Into a 100 mL recovery flask equipped with a stirrer and a nitrogen inlet tube, 2.29 g (11.5 mmol) of DA-4 and 1.75 g (11.5 mmol) of DA-6 were weighed out, 22.9 g of NMP was added, and the mixture was dissolved by stirring while supplying nitrogen. While stirring this diamine solution under water cooling, 0.95 g (4.8 mmol) of CA-2 was added, and then 5.4 g of NMP was added, and the mixture was stirred at 23 ° C. under a nitrogen atmosphere for 30 minutes. Thereafter, while stirring this solution under water cooling, 4.32 g (17.3 mmol) of CA-3 was added, and then 24.5 g of NMP was added, and the mixture was stirred under a nitrogen atmosphere at 50 ° C. for 12 hours to obtain a polymer solution C-3 containing polyamic acid.

(Synthesis Example 12)
Into a 100 mL recovery flask equipped with a stirrer and a nitrogen inlet tube, 2.29 g (11.5 mmol) of DA-4 and 1.75 g (11.5 mmol) of DA-6 were weighed out, 22.9 g of NMP was added, and the mixture was dissolved by stirring while supplying nitrogen. While stirring this diamine solution under water cooling, 2.07 g (10.6 mmol) of CA-2 was added, and then 11.8 g of NMP was added, and the mixture was stirred at 23 ° C. under a nitrogen atmosphere for 30 minutes. Thereafter, while stirring this solution under water cooling, 2.87 g (11.5 mmol) of CA-3 was added, and then 16.2 g of NMP was added, and the mixture was stirred under a nitrogen atmosphere at 50 ° C. for 12 hours to obtain a polymer solution C-4 containing polyamic acid.

(Synthesis Example 13)
Into a 100 mL recovery flask equipped with a stirrer and a nitrogen inlet tube, 3.19 g (16.0 mmol) of DA-4 and 0.79 g (4.0 mmol) of DA-5 were weighed out, 22.6 g of NMP was added, and the mixture was dissolved by stirring while supplying nitrogen. While stirring this diamine solution under water cooling, 2.50 g (10.0 mmol) of CA-3 was added, and then 14.2 g of NMP was added, and the mixture was stirred at 50 ° C. under a nitrogen atmosphere for 2 hours. Thereafter, while stirring this solution under water cooling, 2.71 g (9.2 mmol) of CA-4 was added, and then 15.4 g of NMP was added, and the mixture was stirred under a nitrogen atmosphere at 70 ° C. for 12 hours to obtain a polymer solution C-5 containing polyamic acid.

(Synthesis Example 14)
Into a 100 mL recovery flask equipped with a stirrer and a nitrogen inlet tube, 1.99 g (10.0 mmol) of DA-4 and 1.98 g (10.0 mmol) of DA-5 were weighed out, 22.5 g of NMP was added, and the mixture was dissolved by stirring while supplying nitrogen. While stirring this diamine solution under water cooling, 3.75 g (15.0 mmol) of CA-3 was added, and then 21.3 g of NMP was added, and the mixture was stirred at 50 ° C. under a nitrogen atmosphere for 2 hours. Thereafter, while stirring this solution under water cooling, 1.24 g (4.2 mmol) of CA-4 was added, and then 7.0 g of NMP was added, and the mixture was stirred under a nitrogen atmosphere at 70 ° C. for 12 hours to obtain a polymer solution C-6 containing polyamic acid.

The types and amounts of diamine components and tetracarboxylic acid components used in Synthesis Examples 1 to 14 are summarized in Table 1.

<Preparation of Liquid Crystal Alignment Agent>
Example 1
Using the polymer solution A-1 and the polymer solution B-1, polymer solution A-1 (7.5 g) and polymer solution B-1 (14.0 g) were mixed so that the mass ratio of the two types of polymers was 30: 70. To this mixture, NMP (12.1 g), BCS (12.5 g), an NMP solution (3.0 g) containing 1 mass% of AD-1, and an NMP solution (0.9 g) containing 10 mass% of AD-2 were added with stirring, and the mixture was further stirred at room temperature for 2 hours to obtain a liquid crystal aligning agent AL-1 of the present invention.

(Examples 2 to 5 and Comparative Examples 1 to 10)
With the composition shown in Table 2 below, the same operation as in Example 1 was performed to obtain liquid crystal aligning agents AL-2 to AL-5 which are Examples 2 to 5 of the present invention and liquid crystal aligning agents AL-C1 to AL-C10 which are Comparative Examples 1 to 10.

<Fabrication of Liquid Crystal Cell>
The liquid crystal alignment agent obtained above was used to prepare the following FFS drive liquid crystal cell.
[Configuration of FFS driving liquid crystal cell]
The FFS mode liquid crystal cell was a set consisting of a first glass substrate on which a finger-on-plate (FOP) electrode layer consisting of a planar common electrode, an insulating layer, and a comb-shaped pixel electrode was formed, and a second glass substrate on which a 4 μm-tall columnar spacer was formed on the surface and an ITO film for antistatic purposes was formed on the back surface. The pixel electrode had a comb-like shape in which multiple 3 μm-wide electrode elements, bent at a 160° interior angle in the center, were arranged in parallel with each other at 6 μm intervals. Each pixel had a first region and a second region separated by a line connecting the bends of the multiple electrode elements. The liquid crystal alignment film formed on the first glass substrate was oriented so that the direction dividing the interior angle of the pixel bend was perpendicular to the alignment direction of the liquid crystal, and the liquid crystal alignment film formed on the second glass substrate was oriented so that the alignment direction of the liquid crystal on the first glass substrate was aligned with the alignment direction of the liquid crystal on the second glass substrate when the liquid crystal cell was fabricated.

[Liquid crystal cell fabrication procedure]
A liquid crystal alignment agent filtered through a 1.0 μm pore size filter was applied to the surface of each of the glass substrates by spin coating and dried on a hot plate at 80°C for 2 minutes. This was then baked for 30 minutes in a hot air circulating oven at 230°C to obtain a substrate with a liquid crystal alignment film with a film thickness of 100 nm. The surface of this substrate with the liquid crystal alignment film was rubbed with a rayon cloth (manufactured by Yoshikawa Chemical Co., Ltd., YA-20R) (roller diameter: 120 mm, roller rotation speed: 1000 rpm, movement speed: 20 mm/sec, indentation length: 0.4 mm), then ultrasonically cleaned in pure water for 1 minute, water droplets removed by air blowing, and then dried at 80°C for 15 minutes to obtain a substrate with a liquid crystal alignment film.
Next, spherical spacers with a particle size of 4 μm were dispersed on the liquid crystal alignment film surface of one of the pair of substrates with the liquid crystal alignment film. A sealant (Mitsui Chemicals, Inc., XN-1500T) was then printed around the periphery, leaving the liquid crystal injection port. The other substrate was then attached so that the liquid crystal alignment film surfaces faced each other and the rubbing directions were antiparallel. The substrate was then heated at 150°C for 60 minutes to harden the sealant, producing an empty cell. Liquid crystal MLC-3019 (Merck, positive liquid crystal) was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an FFS-driven liquid crystal cell. The resulting liquid crystal cell was then heated at 120°C for 1 hour and left overnight before undergoing various evaluations.

<Evaluation of liquid crystal cell characteristics>
The properties of the liquid crystal cell prepared above were evaluated as follows.

[Viewing angle characteristics]
The pretilt angle of the liquid crystal cell was measured using an "OPTIPRO-micro" manufactured by SHINTECH Corporation. It can be said that the smaller the pretilt angle, the better the viewing angle characteristics. Specifically, a pretilt angle of 2.0 degrees or less was evaluated as "○", and a pretilt angle of more than 2.0 degrees was evaluated as "×".

[Image retention characteristics due to long-term AC driving]
An AC voltage of ±7 V at 60 Hz was applied to the FFS-driven liquid crystal cell prepared above for 120 hours under a backlight with an illuminance of 15,000 nits. The pixel electrode and the counter electrode of the liquid crystal cell were then shorted, and the cell was left at room temperature for one day. For the liquid crystal cell subjected to the above treatment, the deviation in angle between the alignment direction of the liquid crystal in the first region of the pixel and the alignment direction of the liquid crystal in the second region was calculated in the absence of applied voltage.
Specifically, a liquid crystal cell was placed between two polarizing plates arranged with their polarization axes perpendicular to each other, and the backlight was turned on. The angle of the liquid crystal cell was adjusted so that the transmitted light intensity of the first region of the pixel was minimized. The rotation angle Δ required to rotate the liquid crystal cell so that the transmitted light intensity of the second region of the pixel was minimized was then determined. It can be said that the smaller the value of this rotation angle Δ, the better the image retention characteristics under long-term AC driving. Specifically, a rotation angle Δ of 0.05 degrees or less was evaluated as "Good," and a rotation angle Δ of more than 0.05 degrees was evaluated as "Poor."

<Evaluation results>
Table 3 shows the evaluation results of the liquid crystal cells using the liquid crystal alignment agents of the above Examples and Comparative Examples.

Liquid crystal display elements using the liquid crystal alignment agent of the present invention can be said to have a small pretilt angle and good image retention characteristics.

REFERENCE SIGNS LIST 1 IPS LCD element 2 Comb-tooth electrode substrate 2a Base material 2b Linear electrode 2c Liquid crystal alignment film 2d Base material 2e Planar electrode 2f Insulating film 2g Linear electrode 2h Liquid crystal alignment film 3 Liquid crystal 4 Counter substrate 4a Liquid crystal alignment film 4b Base material L Electric field lines

Claims (13)

A liquid crystal aligning agent comprising the following components (A) and (B):
Component (A): Polyamic acid (A) which is a reaction product of a tetracarboxylic acid derivative component containing an aromatic tetracarboxylic acid dianhydride in an amount of 100 mol % of the total tetracarboxylic acid derivative component, and a diamine component containing a diamine represented by the following formula (d _AL ):
Component (B): Polyamic acid (B) which is a reaction product of a tetracarboxylic acid derivative component containing at least one tetracarboxylic acid dianhydride selected from the group consisting of acyclic aliphatic tetracarboxylic acid dianhydrides and alicyclic tetracarboxylic acid dianhydrides in an amount of 5 mol % or more of the total tetracarboxylic acid derivative components, and a diamine component containing a diamine represented by the following formula (d _AL ) and a diamine represented by the following formula (d _n ):
(In formula (d _AL ), A represents a divalent organic group having the group "* ₁₁ -(CH ₂ ) _n -O-* ₁₂ " (* ₁₁ represents a bond bonded to an oxygen atom or a bond bonded to a carbon atom constituting a benzene ring, * ₁₂ represents a bond, and n is an integer of 1 to 5). Any hydrogen atom of the benzene ring bonded to the NH ₂ group may be replaced with a monovalent group.)
(In formula (d _n ), Y represents a divalent organic group having a nitrogen-atom-containing structure selected from the group consisting of nitrogen-atom-containing heterocycles and amino groups represented by the group "* ₂₁ -NR-* ₂₂ " (* ₂₁ and * ₂₂ represent bonds bonding to carbon atoms constituting the aromatic ring, provided that the carbon atoms do not form a ring with the nitrogen atom to which R is bonded; R represents a hydrogen atom or a monovalent organic group, and the monovalent organic group is bonded to the nitrogen atom at a carbon atom other than the carbonyl carbon).) The liquid crystal aligning agent according to claim 1, wherein the content of the diamine represented by the formula (d _AL ) in the constituent components of the polyamic acid (A) is 10 mol % or more of all diamine components used in the production of the polyamic acid (A). The polyamic acid (A) is a component of the formula (d _AL 2. The liquid crystal aligning agent according to claim 1, wherein the content of the diamine represented by the formula (I) is 50 mol % or more of all diamine components used in the production of the polyamic acid (A). The liquid crystal aligning agent according to any one of claims 1 to 3, wherein the content of the diamine represented by the formula (d _AL ) in the constituent components of the polyamic acid (B) is 5 to 80 mol% of all diamine components used in the production of the polyamic acid (B). The liquid crystal aligning agent according to any one of claims 1 to 4, wherein the content of the diamine represented by the formula ( _dn ) in the constituent components of the polyamic acid (B) is 20 to 95 mol% of all diamine components used in the production of the polyamic acid (B). The liquid crystal aligning agent according to any one of claims 1 to 5 , wherein the diamine represented by the formula (d _AL ) is a diamine represented by the following formulas (d _AL -1) to (d _AL -9):
The above formula (d _AL ) is a diamine represented by the following formula (d _AL The liquid crystal aligning agent according to any one of claims 1 to 5, wherein the diamine is a diamine other than the diamine represented by formula (I-1-1).
The liquid crystal aligning agent according to any one of claims 1 to 7, wherein the diamine represented by the formula (d _n ) is at least one diamine selected from the group consisting of 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, 1,4-bis-(4 _- aminophenyl)-piperazine, 3,6-diaminoacridine, N-ethyl-3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, and diamines represented by the following formulas ( _d n -1) to (d n -3) :
In formula (d _n -1), m1 and m1′ each independently represent an integer of 1 or 2. n1 represents an integer of 1 to 3. _{R 1} has the same meaning as R in the amino group represented by the above formula "* ₂₁ -NR-* ₂₂ ".
When a plurality of R _{1 s} and m1' s are present, the plurality of R _{1 s} and m1' s may be the same or different.
In formula (d _n -2), X ₂ represents a monovalent nitrogen-containing heterocyclic group. n1 is an integer of 1 or 2, and n2 is an integer that satisfies the relationship n1+n2=2. _{L 1} and L ₂ each independently represent a single bond, —CO—, an alkylene group having 1 to 6 carbon atoms, or a divalent organic group in which —O— or —CO— is inserted between the carbon-carbon bonds or at the terminal of the alkylene group having 1 to 6 carbon atoms, and which is bonded to the nitrogen atom via a carbon atom. R represents a hydrogen atom or a methyl group.
When a plurality of X _{2 ,} L ₂ , and R are present, the plurality of X _{2 ,} L ₂ , and R may be the same or different.
In formula (d _n -3), _X3 represents a divalent group having a nitrogen atom-containing heterocyclic ring. _Ar3 represents a divalent aromatic ring group or a divalent saturated nitrogen atom-containing heterocyclic group. Any hydrogen atom in the aromatic ring group or saturated nitrogen atom-containing heterocyclic group may be replaced with a monovalent group.
_L3 represents a single bond, —(CH ₂ ) _n — (n is an integer of 1 to 6), —NR′—, —(CH ₂ ) _n —NR′- (n is an integer of 1 to 6), —O—, —NR′-CO—, —CO-NR′-, —O—CO—, or —CO—O—, and R′ represents a hydrogen atom, a methyl group, or a tert-butoxycarbonyl group.
m3 and m3' each independently represents an integer of 0 to 2, and either m3 or m3' represents an integer of 1 or more.
When a plurality of _Ar3s and _L3s are present, the plurality of _Ar3s and _L3s may be the same or different. The liquid crystal aligning agent according to any one of claims 1 to 8, wherein the acyclic aliphatic tetracarboxylic acid dianhydride and the alicyclic tetracarboxylic acid dianhydride in the component ( B ) are tetracarboxylic acid dianhydrides having at least one partial structure selected from the group consisting of a cyclobutane ring structure, a cyclopentane ring structure, and a cyclohexane ring structure. The liquid crystal aligning agent according to any one of claims 1 to 9 , wherein the content ratio of the (A) component and the (B) component is 10/90 to 90/10 in terms of a mass ratio of [(A) component]/[(B) component]. A liquid crystal alignment film formed using the liquid crystal aligning agent according to any one of claims 1 to 10 . A liquid crystal display device comprising the liquid crystal alignment film according to claim 11 . A method for manufacturing a liquid crystal display element, comprising the following steps (1) to (3):
Step (1): A step of applying the liquid crystal aligning agent according to any one of claims 1 to 10 onto a substrate; Step (2): A step of baking the applied liquid crystal aligning agent to obtain a film; Step (3): A step of performing an alignment treatment on the film obtained in Step (2).