TW202334379A - Liquid crystal alignment agent for optical alignment, liquid crystal alignment film, liquid crystal element, and liquid crystal alignment film manufacturing method wherein the liquid crystal alignment agent for optical alignment contains a polymer (K) and a polymer (L) obtained by reacting a tetracarboxylic acid derivative with diamines - Google Patents

Abstract

The present invention provides a liquid crystal alignment film capable of forming a liquid crystal display element that can maintain a high voltage retention rate without reducing display quality even after prolonged exposure to strong light, and a liquid crystal alignment agent capable of forming the liquid crystal alignment film. A liquid crystal alignment agent for optical alignment which contains a polymer (K) and a polymer (L) that are polymers obtained by reacting a tetracarboxylic acid derivative with diamines, wherein the raw material composition of the polymer (K) contains a compound having a photoreactive structure and no compound represented by formula (1), and the raw material composition of the polymer (L) contains at least one compound represented by formula (1) and no compound having a photoreactive structure. In formula (1), X is a divalent group represented by formula (A), formula (B), or formula (C). In formulas (1) or (A), A1 and A2 are independently -CH3 and so on, a1 and a2 are independently from 0 to 2, n is 1 to 10, and * represents a bonding position with two -NH- in the formula (1).

Description

Liquid crystal alignment agent for photo alignment, liquid crystal alignment film, liquid crystal element and method of manufacturing liquid crystal alignment film

The invention relates to a liquid crystal alignment agent, a liquid crystal alignment film and a liquid crystal element using the liquid crystal alignment film. Specifically, it relates to a liquid crystal alignment agent for photo-alignment (hereinafter, sometimes abbreviated as a liquid crystal alignment agent) used to form a photo-alignment liquid crystal alignment film (hereinafter, sometimes abbreviated as a photo-alignment film), and the use of the liquid crystal A photo-alignment liquid crystal alignment film formed from an alignment agent and a liquid crystal display element having the liquid crystal alignment film.

It is known that a liquid crystal element can control or modulate the alignment state of the liquid crystal layer in the element, so that electromagnetic waves incident into the element can cause optical phenomena such as refraction, scattering, and reflection. Specifically, in addition to the liquid crystal display elements described below, liquid crystal antennas, light control windows, optical compensation materials, and variable phase shifters are also known.

As liquid crystal display elements, there are known twisted nematic (TN) mode, super twisted nematic (Super Twisted Nematic, STN) mode, in-plane switching (IPS) mode, and fringe switching (Fringe) mode. Field Switching (FFS) mode, vertical alignment type Vertical Alignment (VA) (Multi-domain Vertical Alignment (Multi-domain Vertical Alignment)) mode and other liquid crystal display elements with various driving methods. These liquid crystal display elements are used in image display devices of various electronic devices such as televisions and mobile phones, and are being developed with the goal of further improving display quality. Specifically, the performance of liquid crystal display elements can be improved not only through improvements in driving methods and element structures, but also through structural components used in the elements. Moreover, among the structural members used in liquid crystal display elements, the liquid crystal alignment film in particular is one of the important materials related to display quality. In order to meet the requirements for high-quality liquid crystal display elements, the liquid crystal alignment film is also being developed Be active in research.

Here, the liquid crystal alignment film is provided in contact with the liquid crystal layer on a pair of substrates provided on both sides of the liquid crystal layer of the liquid crystal display element, and has the function of aligning the liquid crystal molecules constituting the liquid crystal layer with respect to the substrate with a certain regularity. function. By using a liquid crystal alignment film with high liquid crystal alignment properties, a liquid crystal display element with high contrast and improved afterimage characteristics can be realized (for example, see Patent Document 1 and Patent Document 2).

In the formation of such a liquid crystal alignment film, a solution (varnish) obtained by dissolving polyamide acid, soluble polyimide or polyamide ester in an organic solvent is currently mainly used. When forming a liquid crystal alignment film using these varnishes, the varnish is applied to a substrate, and then the coating film is cured by heating or the like to form a polyimide-based liquid crystal alignment film. If necessary, alignment suitable for the display mode is performed. handle. Known alignment treatment methods include: a rubbing method in which the surface of an alignment film is wiped with a cloth or the like to align the direction of polymer molecules; and a rubbing method in which the alignment film is irradiated with linearly polarized ultraviolet light to cause photoisomerization of polymer molecules. Or photochemical changes such as dimerization, a photo-alignment method that imparts anisotropy to the film. Compared with the rubbing method, the photo-alignment method has higher alignment uniformity and is a non-contact alignment treatment method, so it does not damage the film. , or it can reduce dust, static electricity and other causes of poor display of liquid crystal display elements.

As a liquid crystal alignment film using such a photo-alignment method, for example, Patent Documents 1 to 6 describe using diaminoazobenzene or the like as a raw material and applying photoisomerization technology to obtain anchoring. A photo-alignment film with large energy and good liquid crystal alignment. [Prior art documents] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2010-197999 [Patent Document 2] International Publication No. 2013/157463 [Patent Document 3] Japanese Patent Application Laid-Open No. 2005-275364 [Patent Document 4] Japanese Patent Application Publication No. 2007-248637 [Patent Document 5] Japanese Patent Application Publication No. 2009-069493 [Patent Document 6] International Publication No. 2015/016118

[Problem to be solved by the invention] In recent years, the requirements for high-quality liquid crystal display elements have become higher and higher, and the reliability of high voltage holding ratio (Voltage Holding Ratio, VHR) that can be maintained for a long time is required. In order to suppress deterioration in display quality, it is important to maintain a high voltage retention rate. On the other hand, considering outdoor use, the brightness of the backlight serving as the light source is also required to be higher than before. When exposed to such a high-brightness backlight, it is important to improve the VHR reliability against light, which becomes a particularly important issue in photo-alignment films that generally have poorer electrical properties than friction alignment films.

Therefore, the inventors of the present invention provide a liquid crystal alignment film that can maintain a high voltage retention rate without deteriorating the display quality even if exposed to strong light for a long time, and provide a liquid crystal alignment film that can form such a liquid crystal alignment film. Research efforts have been made for the purpose of liquid crystal alignment agents. [Technical means to solve problems]

As a result of diligent research to solve the above problems, the present inventors found that by using the compound represented by formula (1), an alignment film that maintains a high voltage holding ratio can be obtained, and that by using the alignment film, it is possible to form The present invention was completed by displaying a liquid crystal display element with excellent display quality. The present invention includes the following structures.

[1] A liquid crystal alignment agent for photo alignment, comprising a polymer (K) and a polymer (L) which are polymers obtained by reacting a tetracarboxylic acid derivative and a diamine, and the liquid crystal alignment agent for photo alignment is In the agent, the raw material composition of the polymer (K) contains a compound with a photoreactive structure and does not contain a compound represented by the formula (1); and, the raw material composition of the polymer (L) contains the formula ( 1) At least one of the represented compounds and does not include compounds with photoreactive structures. In formula (1), A ¹ is independently -CH ₃ or -OCH ₃ , a1 is independently an integer from 0 to 2, and X is a divalent compound represented by formula (A), formula (B) or formula (C). base, In the formula (A), * represents a bonding bond and represents the bonding position with the two -NH- in the formula (1), A ² is independently -CH ₃ or -OCH ₃ , and a2 is independently 0~ An integer of 2, n is an integer of 1 to 10, In the formula (B), * represents a bonding bond and represents the bonding position with the two -NH- in the formula (1). A ³ is independently -CH ₃ or -OCH ₃ , and a3 is independently 0~ an integer of 2, In formula (C), * is a bonding bond and represents the bonding position with the two -NH- in formula (1), m is an integer from 0 to 3, formula (1), formula (A) and formula In (B), the group whose bonding position is not fixed on any carbon atom constituting the ring means that it can bond with any carbon atom on the ring that can be bonded. In formula (1), when X is In the case of a divalent group represented by formula (A) or formula (B), the bonding position of -NH ₂ on the benzene ring is independently meta-position or para-position based on the carbon bonded to -NH-. [2] The liquid crystal alignment agent for photo alignment according to [1], wherein the compound represented by formula (1) is at least one of the compounds represented by formula (1A-1) to formula (1A-6). [3] The liquid crystal alignment agent for photo alignment according to [1], wherein the compound represented by formula (1) is at least one of the compounds represented by formula (1B-1) to formula (1B-3). [4] The liquid crystal alignment agent for photo alignment according to [1], wherein the compound represented by the formula (1) is at least one of the compounds represented by the formula (1C-1) and the formula (1C-2). [5] The liquid crystal alignment agent for photo-alignment according to any one of [1] to [4], wherein the photoreaction caused by the photoreactive structure is photoisomerization, photo-Fries rearrangement, At least one of decomposition and photodimerization. [6] The liquid crystal alignment agent for photo alignment according to any one of [1] to [5], wherein the compound with a photoreactive structure contained in the raw material composition of the polymer (K) is of the formula (2) At least one of the compounds represented. In formula (2 ⁾ _, R ^b is each independently a hydrogen atom, -CH ₃ , -OCH ₃ , -CF ₃ , -F, -COOCH ₃ , or a monovalent group represented by formula (P1-1) or formula (P1-2), R ^c is independently a hydrogen atom, -CH ₃ , -OCH ₃ , -CF ₃ , -F, or a monovalent group represented by formula (P1-1) or formula (P1-2), j is 0 or 1, a～c are independently integers from 0 to 2, In formula (P1-1) and formula (P1-2), R ^6a , R ^7a and R ^8a respectively independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkyl group , a substituted or unsubstituted alkoxycarbonyl group, or a substituted or unsubstituted arylcarbonyl group, * is a bonding bond, and represents the bonding position to the benzene ring in formula (2), formula (2) ), a group whose bonding position is not fixed on any one of the carbon atoms constituting the ring means that it can bond with any one of the bondable carbons on the ring. [7] The liquid crystal alignment agent for photo alignment according to [6], wherein the compound represented by formula (2) is at least one of the compounds represented by formula (2-1) to formula (2-3). In the formula (2-1), R ^1a and R ^1c each independently represent a hydrogen atom or a monovalent group represented by the formula (P1-1) or the formula (P1-2). In the formula (2-2), R ^2a and R ^2b each independently represent a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2), and R ^2c each independently represents a hydrogen atom, -CH ₃ , -OCH ₃ , - CF _{3 or -F} , An integer from 0 to 2. In the formula (2-3), R ^3a represents a hydrogen atom or a monovalent group represented by the formula (P1-1) or the formula (P1-2), and R ⁴ and R ⁵ are each independently Hydrogen atom or -F, R ⁴ and R ⁵ are not hydrogen atoms at the same time, R ^3c is independently a hydrogen atom, -CH ₃ , -OCH ₃ , -CF ₃ or -F, and X ₁ is carbon number 1 to 12. Alkylene group, in the alkylene group, more than one non-adjacent -CH ₂ - can be substituted by -O- or -NH-, m is an integer from 0 to 2, In formula (P1-1) and formula (P1-2), R ^6a , R ^7a and R ^8a respectively independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkyl group , substituted or unsubstituted alkoxycarbonyl, or substituted or unsubstituted arylcarbonyl, * is a bond, and represents the same as formula (2-1), formula (2-2) or formula ( 2-3) The bonding position of the benzene ring in formula (2-1), formula (2-2) and formula (2-3), the bonding position is not fixed on any carbon atom constituting the ring The group represents a bond that can be bonded to any of the carbons on the ring that can be bonded. [8] The liquid crystal alignment agent for photo alignment according to any one of [1] to [5], wherein the compound with a photoreactive structure contained in the raw material composition of the polymer (K) is of the formula (3) At least one of the compounds represented. In formula (3), R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. R ¹ and R ² may be integrated to form a methylene group, and Independently represents an integer from 0 to 4. [9] The liquid crystal alignment agent for photo alignment according to any one of [1] to [8], further containing an additive. [10] The liquid crystal alignment agent for photo alignment according to [9], wherein the additive is at least one selected from the group consisting of oxazoline compounds and epoxy compounds. [11] A liquid crystal alignment film formed from the liquid crystal alignment agent for photo alignment according to any one of [1] to [10]. [12] A liquid crystal element having the liquid crystal alignment film according to [11]. [13] A method of manufacturing a liquid crystal alignment film, including: coating the liquid crystal alignment agent for optical alignment according to any one of [1] to [10] on a substrate; and irradiating the coating film with polarized light UV steps. [Effects of the invention]

By using the liquid crystal alignment agent of the present invention, a liquid crystal alignment film that can maintain a high voltage retention rate can be obtained.

Hereinafter, the present invention will be described in detail. The description of the structural elements described below may be based on representative embodiments or specific examples, but the present invention is not limited to such embodiments. The "liquid crystal alignment agent" in the present invention is a liquid crystal alignment agent that can impart anisotropy by irradiating polarized ultraviolet rays when the film is formed on a substrate. In this specification, it may sometimes be simply referred to as a "liquid crystal alignment agent" , it is sometimes also called "liquid crystal alignment agent for photo alignment". In addition, in the present invention, the "tetracarboxylic acid derivative" means tetracarboxylic dianhydride, tetracarboxylic acid diester or tetracarboxylic acid diester dihalide. In addition, in the present invention, diamines and dihydrazides may be referred to as “diamines”.

<Liquid crystal alignment agent for photo-alignment of the present invention> The liquid crystal alignment agent for photo alignment of the present invention contains at least one of the following polymers (K) and at least one of the following polymers (L). The polymer (K) is a polymer that contains at least one compound having a photoreactive structure in the raw material monomers used for synthesis and does not contain the compound represented by formula (1). In addition, the polymer (L) is a polymer that contains at least one compound represented by formula (1) in the raw material monomers used for synthesis and does not contain a compound having a photoreactive structure. The polymer (K) and the polymer (L) may each be referred to as the polymer of the present invention.

<Compound represented by formula (1)> The compound represented by formula (1) used for the polymer (L) contained in the liquid crystal alignment agent of the present invention will be described. In formula (1), A ¹ is independently -CH ₃ or -OCH ₃ , a1 is independently an integer from 0 to 2, and X is a divalent compound represented by formula (A), formula (B) or formula (C). base. In the formula (A), * represents a bonding bond and represents the bonding position with the two -NH- in the formula (1), A ² is independently -CH ₃ or -OCH ₃ , and a2 is independently 0~ An integer of 2, n is an integer of 1 to 10. In the formula (B), * represents a bonding bond and represents the bonding position with the two -NH- in the formula (1). A ³ is independently -CH ₃ or -OCH ₃ , and a3 is independently 0~ an integer of 2. In the formula (C), * represents a bonding bond and represents a bonding position with two -NH- in the formula (1), and m is an integer from 0 to 3. In formula (1), formula (A) and formula (B), the group whose bonding position is not fixed on any carbon atom constituting the ring means any bond capable of bonding with any carbon on the ring that can be bonded Knot, in formula (1), when X is a divalent group represented by formula (A) or formula (B), the bonding position of -NH ₂ on the benzene ring is based on the carbon connected to -NH-. Independently meta or counterposition.

The compound represented by formula (1) is a compound having a diphenylamine structure. The diamines used in the polymer (L) of the present invention include at least one compound represented by formula (1).

By using the compound represented by Formula (1) as a raw material of the polymer (L), a liquid crystal display element that maintains a high voltage retention rate even when exposed to strong light for a long time can be formed. The reason is not necessarily clear, but it is thought to be as follows.

It is believed that the diphenylamine structure has the function of capturing free radicals. When a liquid crystal display element is exposed to light for a long time, free radicals are generated due to degradation of polymers, etc., which is considered to be one of the causes of a decrease in the voltage holding ratio. The diphenylamine structure of formula (1) can capture the generated free radicals, thereby maintaining a high voltage retention rate.

The content of the compound represented by formula (1) in the polymer (L) is preferably 10 mol% to 100 mol%, more preferably 20 mol% to 100 mol% relative to the total amount of diamine in the monomer. Ear%.

Specific examples of the compound represented by formula (1) are listed below.

Among these compounds, compounds represented by formula (1A-1) to formula (1A-4), formula (1B-1), formula (1B-2), and formula (1C-2) are preferred.

＜Compounds with photoreactive structures＞ The compound having a photoreactive structure used as a raw material of the polymer (K) contained in the liquid crystal alignment agent of the present invention will be described. In this specification, a photoreactive structure refers to a structure that causes a photoreaction by irradiating light containing a unique wavelength band corresponding to the photoreactive structure. Examples of photoreactions include photoisomerization, photoFries rearrangement, photodecomposition, and photodimerization. The photoreactive structure can be introduced into the polymer by using a compound having a photoreactive structure as a raw material. In addition, in this specification, regarding the compounds listed as compounds having a photoreactive structure, in the process of forming the alignment film from the liquid crystal alignment agent, the light containing the inherent wavelength band corresponding to the photoreactive structure is not irradiated. In the case of , a compound without a photoreactive structure may also be used as a raw material.

The Liquid Crystal Alignment Agent for Photo Alignment of the Invention When the coating film of the liquid crystal alignment agent for photo alignment is irradiated with polarized light of a prescribed wavelength during the formation of the liquid crystal alignment film, the photoreactive structure of the polymer backbone is substantially parallel to the polarization direction. By causing a photoreaction, components in the polymer chain oriented in a specific direction (a direction that is approximately at right angles to the polarization direction of the irradiated light) dominate, thereby imparting anisotropy to the coating film. The state in which the component facing a specific direction in the polymer chain occupies a dominant lower position is expressed as the polymer chain being aligned. When the optical alignment film formed by calcining the coating film is used in a liquid crystal display element, the surface of the aligned film interacts with the liquid crystal molecules. As a result, the liquid crystal molecules align in a certain direction (relative to the polarization direction of the irradiated light). (and in a roughly right-angled direction) so that the long axes are aligned.

<Structure causing photoisomerization reaction> Examples of the structure causing photoisomerization reaction in the present invention include a structure having an azobenzene skeleton. In this specification, the structure having an azobenzene skeleton means a structure represented by the following formula (D). In the formula (D), * represents a bonding bond, the bonding position of the bonding bond and the benzene ring is independently any one of the carbons on the ring that can be bonded, and the hydrogen atom of the benzene ring that can be substituted May be substituted with substituents. Specific examples of the substituent may refer to the corresponding groups (R ^a , R ^b ) of the following formula (2).

The compound having a structure that causes a photoisomerization reaction used in the polymer (K) contained in the liquid crystal alignment agent for photo alignment of the present invention is specifically a compound represented by formula (2). In formula (2 ⁾ _, R ^b is independently a hydrogen atom, -CH ₃ , -OCH ₃ , -CF ₃ , -F, -COOCH ₃ , or a monovalent group represented by formula (P1-1) or formula (P1-2), R ^c is independently a hydrogen atom, -CH ₃ , -OCH ₃ , -CF ₃ , -F, or a monovalent group represented by formula (P1-1) or formula (P1-2), j is 0 or 1, a～c are independently integers from 0 to 2,

In formula (P1-1) and formula (P1-2), R ^6a , R ^7a and R ^8a respectively independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkyl group , a substituted or unsubstituted alkoxycarbonyl group, or a substituted or unsubstituted arylcarbonyl group, R ^6a , R ^7a and R ^8a may be the same as each other or different, * represents a bond, and represents a The bonding position of the benzene ring in formula (2). In formula (2), the bonding position is not fixed on any carbon atom constituting the ring. It means that it can bond with the carbon on the ring. Any bond. In Formula (P1-1) and Formula (P1-2), the alkyl group in R ^6a , R ^7a and R ^8a may be linear, branched or cyclic. The alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 4 carbon atoms, and even more preferably 1 to 3 carbon atoms. Specific examples of the alkyl group include: methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, tert. Pentyl, 1-methylbutyl, 1-ethylpropyl, hexyl, isohexyl, 1-methylpentyl, 1-ethylbutyl, etc.

The alkyl group in R ^6a , R ^7a and R ^8a may be linear, branched or cyclic. The alkyl group has preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, still more preferably 1 to 2 carbon atoms, and even more preferably 1 carbon number. Specific examples of the alkyl group include formyl, acetyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, and neopentyl. Cyl group, tert-pentyl group, 1-methylbutyl group, 1-ethyl propyl group, hexyl group, isohexyl group, 1-methyl pentyl group, 1-ethyl butyl group, etc.

The alkoxycarbonyl group in R ^6a , R ^7a and R ^8a may be linear, branched or cyclic. The alkoxycarbonyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, even more preferably 1 to 3 carbon atoms, and even more preferably 2 carbon atoms. Specific examples of the alkoxycarbonyl group include: methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl, isobutoxycarbonyl, sec-butoxycarbonyl, tert-butoxycarbonyl, pentyloxycarbonyl, isopentoxycarbonyl, neopentyloxycarbonyl, tert-pentyloxycarbonyl, 1-methylbutoxycarbonyl, 1-ethylpropoxycarbonyl, hexyloxy Carbonyl, isohexyloxycarbonyl, 1-methylpentoxycarbonyl, 1-ethylbutoxycarbonyl, etc.

The aryl group of the arylcarbonyl group in R ^6a , R ^7a and R ^8a may be a single ring or a condensed ring. The aryl group preferably has 6 to 22 carbon atoms, more preferably 6 to 14 carbon atoms, and even more preferably 6 to 10 carbon atoms. Specific examples of the aryl group include phenyl, 1-naphthyl, 2-naphthyl, and the like. Specific examples of the arylcarbonyl group include phenylcarbonyl group, 1-naphthylcarbonyl group, and the like. The alkyl group, alkyl group and arylcarbonyl group in R ^6a , R ^7a and R ^8a respectively may be substituted by substituents. Examples of the substituent include hydroxyl group, amino group, halogen, etc. Among these, R ^6a , R ^7a and R ^8a are each independently preferably a methyl group, an ethyl group, a propyl group, a hydrogen atom, a formyl group, phenyl.

The compound represented by formula (2) is specifically a compound represented by the following formula (2-1) to formula (2-3). In formula (2-1), R ^1a and R ^1c each independently represent a hydrogen atom, a monovalent group represented by formula (P1-1) or formula (P1-2), and in formula (2-2), R ^2a and R ^2b each independently represent a hydrogen atom, a monovalent group represented by formula (P1-1) or formula (P1-2), and R ^2c each independently represents a hydrogen atom, -CH ₃ , -OCH ₃ , -CF _{3 Or -F} , An integer of 2, in formula (2-3), R ^3a represents a hydrogen atom, a monovalent group represented by formula (P1-1) or formula (P1-2), R ⁴ and R ⁵ are each independently a hydrogen atom or -F, R ⁴ and R ⁵ are not hydrogen atoms at the same time, R ^3c is independently a hydrogen atom, -CH ₃ , -OCH ₃ , -CF ₃ or -F, X ₁ is an alkane with 1 to 12 carbon atoms. group, in the alkylene group, more than one non-adjacent -CH ₂ - can be substituted by -O- or -NH-, m is an integer from 0 to 2, In formula (P1-1) and formula (P1-2), R ^6a , R ^7a and R ^8a respectively independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkyl group , a substituted or unsubstituted alkoxycarbonyl group, or a substituted or unsubstituted arylcarbonyl group, R ^6a , R ^7a and R ^8a may be the same as each other or different, * represents a bond, and represents a The bonding position of the benzene ring in formula (2-1), formula (2-2) and formula (2-3), in formula (2-1), formula (2-2) and formula (2-3) , a group whose bonding position is not fixed on any carbon atom constituting the ring means that it can bond with any carbon on the ring that can be bonded.

In formula (P1-1) and formula (P1-2) of formula (2-1) to formula (2-3), regarding the alkyl group, alkyl group and alkoxy group in R ^6a , R ^7a and R ^8a For descriptions of carbonyl groups, arylcarbonyl groups and substituents that can be substituted on these groups, as well as preferred ranges and specific examples, refer to formula (P1-1) of formula (2) and formula (P1-2). Description of R ^6a , R ^7a and R ^8a .

Specific examples of the compound represented by formula (2-1) include the following compounds. In formula (2-1-2), R ^6a is an alkyl group having 1 to 4 carbon atoms.

Specific examples of the compound represented by formula (2-2) include the following compounds. In formula (2-2-1) to formula (2-2-6), R ^6a is an alkyl group having 1 to 4 carbon atoms, l is an integer of 1 to 10, and m is an integer of 1 to 11.

Specific examples of the compound represented by formula (2-3) include the following compounds. In Formula (2-3-1) and Formula (2-3-2), l is an integer from 1 to 10.

When emphasis is placed on the transparency of the liquid crystal alignment film formed, it is preferable to use a product selected from the group consisting of formula (2-1-2), formula (2-1-3), formula (2-2-3), formula (2 -2-4), any one or more compounds in the group consisting of formula (2-2-5) and formula (2-2-6), more preferably formula (2-1-2) or formula ( 2-1-3), particularly preferably the compound in which R ^6a in formula (2-1-2) is ethyl.

When it is important to obtain a liquid crystal alignment film (that is, a liquid crystal alignment agent with high sensitivity) that can form an element with good afterimage characteristics even if the energy is small during the alignment process, it is preferable to use a liquid crystal alignment agent selected from the formula (2-1 -2), formula (2-1-3), formula (2-2-3), formula (2-2-4), formula (2-2-5), formula (2-2-6), formula Any one or more compounds in the group consisting of (2-3-1) and formula (2-3-2), more preferably formula (2-1-2), formula (2-3-1) or The formula (2-3-2) is more preferably a compound in which R ^6a in the formula (2-1-2) is an ethyl group or a compound represented by l=2 to 6 in the formula (2-3-1).

In order to further improve the VHR reliability of the liquid crystal display element, it is preferable to use formulas selected from formula (2-1-2), formula (2-1-3), formula (2-2-1), and formula (2-2-2 ), any one or more compounds in the group consisting of formula (2-2-3), formula (2-2-4), formula (2-2-5) and formula (2-2-6), More preferably, they are compounds represented by formula (2-1-2), formula (2-1-3) or formula (2-2-1) in which l=2 to 6, and even more preferably, they are compounds represented by formula (2-1-2 ) in which R ^6a is an ethyl compound or a compound represented by l=2 to 6 in formula (2-2-1).

When emphasis is placed on obtaining a liquid crystal display element with high contrast, it is preferable to use one selected from the group consisting of Formula (2-1-1), Formula (2-2-1) and Formula (2-2-2). Any one or more compounds of the formula (2-1-1) or the compound represented by l=2 to 6 in the formula (2-2-1) are more preferred. In this case, relative to the total amount of diamine in the monomer, the polymer (K) is selected from the group consisting of formula (2-1-1), formula (2-2-1) and formula (2-2- 2) The total content of the compounds in the group is preferably 40 mol% to 95 mol%, and more preferably 70 mol% to 90 mol%.

<Compound having a structure causing a photo-Friis rearrangement reaction> Examples of a structure causing a photo-Friis rearrangement reaction in the present invention include a structure having a phenyl ester skeleton. In this specification, the structure having a phenyl ester skeleton means a structure represented by the following formula (E). In the formula (E), * represents a bonding bond, the bonding position of the bonding bond and the benzene ring is independently any one of the carbons on the ring that can be bonded, and the hydrogen atom of the benzene ring that can be substituted May be substituted with substituents. Preferable examples of the compound having a structure that causes photo-Frisian rearrangement used in the polymer (K) contained in the liquid crystal alignment agent of the present invention include the following formula (3). In addition, examples of compounds having a structure that causes a photo-Frisian rearrangement reaction include formula (AN-4-32) to formula (AN-4-36), formula (DI-5-32), formula (DI -5-33), compounds represented by formula (DI-5-35) and formula (DI-6-8) to formula (DI-6-10). In formula (3), R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. R ¹ and R ² may be integrated to form a methylene group. X each independently represents a halogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, and n independently represents an integer of 0 to 4. m in the formula (DI-5-35) represents an integer from 0 to 12.

Among these compounds, from the viewpoint of producing a liquid crystal display element with high contrast, it is preferable to use a compound represented by formula (3), and more preferably to use a compound in which the amine group on each benzene ring in formula (3) is used relative to the ester group. Compounds in the para position. In addition, the total content of the compounds represented by formula (3) in the polymer (K) is preferably 40 mol% to 100 mol%, and more preferably 70 mol% relative to the total amount of diamines in the monomers. ~100 mol%.

Specific examples of the compound represented by formula (3) include compounds represented by the following formula (3-1) to formula (3-6). Among these compounds, the compound represented by formula (3-4) is more preferable in terms of characteristics.

<Structure causing photodecomposition reaction> Examples of the structure causing photodecomposition reaction in the present invention include a structure having a cyclobutanetetracarboxylic acid skeleton. In this specification, the structure having a cyclobutanetetracarboxylic acid skeleton means a structure represented by the following formula (F). In formula (F), *1, *1', *2 and *2' are bonding keys. Which group or two groups of *1 and *1' and *2 and *2' can be combined with The same O is used for bonding. That is, the acid anhydride -CO-O-CO- can be formed. R ^b1 , R ^b2 , R ^b3 and R ^b4 are each independently a monovalent organic group.

Preferable examples of the compound having a structure that causes a photodecomposition reaction used in the polymer (K) contained in the liquid crystal alignment agent of the present invention include the following formulas (PA-1) to formula (PA-6) the compound represented. In formula (PA-3) to formula (PA-6), R ¹¹ is independently an alkyl group having 1 to 5 carbon atoms.

<Structure causing photodimerization reaction> Examples of the structure causing photodimerization reaction in the present invention include a structure having a cinnamic acid skeleton. In this specification, the structure having a cinnamic acid skeleton means a structure represented by the following formula (G). In formula (G), * represents a bonding bond, the bonding position of the bonding bond and the benzene ring is independently any one of the carbons on the ring that can be bonded, and the hydrogen atom of the benzene ring that can be substituted May be substituted with substituents.

Preferable examples of the compound having a structure that causes a photodimerization reaction used in the polymer (K) contained in the liquid crystal alignment agent of the present invention include the following formulas (PDI-9) to formula (PDI-13 ) represented by the compound. In the formula (PDI-12), R ¹² is an alkyl group or alkoxy group having 1 to 10 carbon atoms, and at least one hydrogen atom of the alkyl group or alkoxy group may be substituted by a fluorine atom.

＜Types of polymer＞ The polymer (K) and the polymer (L) of the present invention are polymers obtained by reacting a tetracarboxylic acid derivative and a diamine, and are polyamic acid or a polyamic acid derivative. Polyamic acid and polyamic acid derivatives will be described in detail below.

Polyamic acid is a polymer synthesized by the polymerization reaction of diamines represented by formula (DI) and tetracarboxylic dianhydride represented by formula (AN), and has a structural unit represented by formula (PAA). When the liquid crystal alignment agent containing polyamide is heated and calcined in the step of forming the liquid crystal alignment film, the polyamide is imidized to form a polyamide having a structural unit represented by formula (PI). Amine liquid crystal alignment film.

In formula (AN), formula (PAA) and formula (PI), X ¹ is a tetravalent organic group. In formula (DI), formula (PAA) and formula (PI), X ² is a divalent organic group. Regarding the preferred range and specific examples of the tetravalent organic group in X ¹ , refer to the structure corresponding to the tetracarboxylic dianhydride described in the column of tetracarboxylic acid derivatives below. Regarding the preferred range and specific examples of the divalent organic group ⁱⁿ Records related to the structure corresponding to hydrazine.

Polyamic acid derivatives are compounds whose characteristics are changed by substituting part of polyamic acid with other atoms or atomic groups. Polyamic acid derivatives are particularly preferred for their improved solubility in solvents used in liquid crystal alignment agents. derivative. Specific examples of such polyamide derivatives include: 1) polyimides obtained by dehydration and ring-closure reaction of all amine groups and carboxyl groups of polyamide; 2) polyimides obtained by partial dehydration and ring-closure reaction. 3) Polyamide ester formed by converting the carboxyl group of polyamide acid into ester, 4) Substituting part of the acid dianhydride contained in the tetracarboxylic dianhydride compound with organic Polyamide-polyamide copolymer obtained by reacting dicarboxylic acid, and 5) polyamide obtained by subjecting part or all of the polyamide-polyamide copolymer to dehydration and ring-closure reaction acyl imine. Among these derivatives, for example, the polyimide has a structural unit represented by the formula (PI), and the polyamide ester has the formula (PAE). Represents the structural unit of polyamide ester. In the formula (PAE), X ¹ is a tetravalent organic group, X ² is a divalent organic group, and Y is independently an alkyl group. Regarding the preferred ranges and specific examples of X ¹ and X ² , please refer to the description related to X ¹ and X ² in the formula (PAA). Among Y, a linear or branched chain alkyl group having 1 to 6 carbon atoms is preferred, and a methyl, ethyl, propyl, isopropyl, butyl, isobutyl or tert-butyl group is more preferred.

Polyamic acid can be obtained as a reaction product obtained by the polymerization reaction of tetracarboxylic dianhydride and diamines. Regarding the description, preferred range, and specific examples of tetracarboxylic dianhydride, refer to the description in the column of tetracarboxylic acid derivatives below. For description, preferred ranges, and specific examples of diamines, refer to the description in the column of diamines below.

The number of tetracarboxylic dianhydrides and diamines used in the synthesis of polyamic acid may be one type or two or more types, respectively.

When the polyamic acid of the present invention is a polyimide which is a polyamic acid derivative, the obtained polyamic acid solution is mixed with acetic anhydride, propionic anhydride as a dehydrating agent, Acid anhydrides such as trifluoroacetic anhydride and tertiary amines such as triethylamine, pyridine, and tricopyridine as dehydration ring-closure catalysts are subjected to an imidization reaction at a temperature of 20°C to 150°C to obtain polyimide. Alternatively, a large amount of poor solvents (alcohol-based solvents such as methanol, ethanol, isopropyl alcohol or glycol-based solvents) may be used to precipitate polyamic acid from the obtained polyamic acid solution, and the precipitated The polyamide imide is carried out in a solvent such as toluene and xylene together with the dehydrating agent and dehydration ring-closing catalyst at a temperature of 20°C to 150°C to obtain the polyimide.

In the imidization reaction, the ratio of the dehydrating agent to the dehydration ring-closing catalyst is preferably 0.1 to 10 (molar ratio). The total usage amount of the dehydrating agent and the dehydration ring-closure catalyst is preferably 1.5 times molar to 10 times molar relative to the total molar amount of tetracarboxylic dianhydride used in the synthesis of the polyamic acid. By adjusting the dehydrating agent, catalyst amount, reaction temperature and reaction time used in the imidization reaction, the degree of imidization can be controlled, and thereby only a part of the polyamic acid can be imidized. Partially made of polyimide. The obtained polyimide can also be separated from the solvent used in the reaction and redissolved in other solvents to be used as a liquid crystal alignment agent, or it can be used as a liquid crystal alignment agent without being separated from the solvent.

Polyamic acid ester can be obtained by the following method: a method of synthesis by reacting polyamic acid with a hydroxyl-containing compound, a halide, an epoxy group-containing compound, or the like, or by derivatizing it from tetracarboxylic dianhydride A method of synthesizing tetracarboxylic acid diester or tetracarboxylic acid diester dichloride by reacting with diamines. The tetracarboxylic acid diester derived from tetracarboxylic dianhydride can be obtained, for example, by reacting the tetracarboxylic acid dianhydride with 2 equivalents of alcohol and opening the ring. The tetracarboxylic acid diester dichloride can be obtained by reacting the tetracarboxylic acid diester with 2 equivalents of alcohol. Obtained by reacting an equivalent amount of chlorinating agent (for example, thionite chloride, etc.). In addition, the polyamic acid ester may have only a amino acid ester structure, or may be a partial esterification product in which a amino acid structure and a amino acid ester structure coexist.

The polyamic acid or its derivatives of the present invention can be produced in the same manner as known polyamic acid or its derivatives used for the formation of a polyimide film. The total input amount of tetracarboxylic dianhydrides is preferably 0.9 mole to 1.1 mole relative to 1 mole of the total diamines.

The liquid crystal alignment agent of the present invention may contain only one type of polyamic acid and polyamic acid derivatives, or may contain two types. For example, the combination of the polymer (K) and the polymer (L) may be polyamic acids or polyamic acid and polyamic acid ester.

The molecular weight of the polymer (K) of the present invention is preferably 5,000 to 500,000, and more preferably 5,000 to 50,000 in terms of weight average molecular weight (Mw) in terms of polystyrene. The molecular weight of the polymer (L) is preferably 5,000 to 500,000, more preferably 10,000 to 500,000 in terms of weight average molecular weight (Mw) in terms of polystyrene. The molecular weight of polyamide or its derivative can be determined by measurement using gel permeation chromatography (GPC).

The existence of the polyamide of the present invention or its derivatives can be confirmed by the following methods: using infrared spectroscopy (IR) and nuclear magnetic resonance (NMR) to analyze the polyamide of the invention. The solid content obtained by precipitating an acid or its derivative in a large amount of poor solvent is analyzed. In addition, the monomers used can be confirmed by the following methods: Gas Chromatography (GC), High Performance Liquid Chromatography (HPLC) or Gas Chromatography-Mass Spectrometry (Gas Chromatography-Mass) Spectrometry, GC-MS) analyzes the extract extracted from the decomposed product using an organic solvent after decomposing the polyamic acid or its derivative using an aqueous solution of a strong base such as KOH or NaOH.

＜Tetracarboxylic acid derivatives＞ The tetracarboxylic acid derivative used as a raw material for the polymer of the present invention can be selected from known tetracarboxylic acid derivatives without limitation.

Examples of other tetracarboxylic dianhydrides are listed below. These tetracarboxylic dianhydrides may be derived into tetracarboxylic acid diesters or tetracarboxylic acid diester dichlorides and used as raw materials for polymers.

This kind of tetracarboxylic dianhydride can be an aromatic system (including heteroaromatic ring system) in which the dicarboxylic anhydride is directly bonded to the aromatic ring, and an aliphatic system (including heteroaromatic ring system) in which the dicarboxylic anhydride is not directly bonded to the aromatic ring. Tetracarboxylic dianhydrides in any group of ring systems).

Examples of such tetracarboxylic dianhydride include the following formulas (AN-1) to formula (AN-9), formula (AN-11), formula (AN-12), and formula (AN-15), Compounds represented by formula (AN-10-1), formula (AN-10-2), and formula (AN-16-1) to formula (AN-16-19).

[Tetracarboxylic dianhydride represented by formula (AN-1)] In formula (AN-1), G ¹¹ is a single bond, an alkylene group having 1 to 12 carbon atoms, a 1,4-phenylene group or a 1,4-cyclohexylene group. X ¹¹ is independently a single bond or -CH ₂ -. G ¹² is independently any one of the following trivalent groups. When G ¹² is >CH-, the hydrogen atom of >CH- may be substituted by a methyl group. When G ¹² is >N-, G ¹¹ is not a single bond and -CH ₂ -, and X ¹¹ is not a single bond. R ¹¹ is independently a hydrogen atom or a methyl group.

Examples of the tetracarboxylic dianhydride represented by formula (AN-1) include compounds represented by the following formulas (AN-1-1) to formula (AN-1-15). In Formula (AN-1-2) and Formula (AN-1-14), m is an integer from 1 to 12.

[Tetracarboxylic dianhydride represented by formula (AN-2)] In formula (AN-2), R ⁶¹ is independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a phenyl group.

Examples of the tetracarboxylic dianhydride represented by formula (AN-2) include compounds represented by the following formulas (AN-2-1) to formula (AN-2-3).

[Tetracarboxylic dianhydride represented by formula (AN-3)] In formula (AN-3), ring A ¹¹ is a cyclohexane ring or benzene ring.

Examples of the tetracarboxylic dianhydride represented by formula (AN-3) include compounds represented by the following formula (AN-3-1) and formula (AN-3-2).

[Tetracarboxylic dianhydride represented by formula (AN-4)] In formula (AN-4), G ¹³ is a single bond, -(CH ₂ ) _m -, -O-, -S-, -C(CH ₃ ) ₂ -, -SO ₂ -, -CO-, -C (CF ₃ ) ₂ - or a divalent group represented by the following formula (G13-1), m is an integer from 1 to 12. Ring A ¹¹ is each independently a cyclohexane ring or a benzene ring. G ¹³ can be bonded to any position of ring A ¹¹ . In the formula (G13-1), G ^13a and G ^13b are each independently a single bond, a divalent group represented by -O-, -CONH- or -NHCO-. The phenylene group is preferably 1,4-phenylene or 1,3-phenylene.

Examples of the tetracarboxylic dianhydride represented by formula (AN-4) include compounds represented by the following formulas (AN-4-1) to formula (AN-4-31). In the formula (AN-4-17), m is an integer from 1 to 12.

[Tetracarboxylic dianhydride represented by formula (AN-5)] In formula (AN-5), R ¹¹ is independently a hydrogen atom or a methyl group. Among the two R ¹¹ s, R ¹¹ on the benzene ring is bonded to any of the substituted positions of the benzene ring.

Examples of the tetracarboxylic dianhydride represented by formula (AN-5) include compounds represented by the following formulas (AN-5-1) to formula (AN-5-3).

[Tetracarboxylic dianhydride represented by formula (AN-6)] In formula (AN-6), X ¹¹ is independently a single bond or -CH ₂ -. X ¹² is -CH ₂ -, -CH ₂ CH ₂ - or -CH=CH-. n is 1 or 2. When n is 2, the two X ^12's may be the same as each other or different.

Examples of the tetracarboxylic dianhydride represented by formula (AN-6) include compounds represented by the following formulas (AN-6-1) to formula (AN-6-12).

[Tetracarboxylic dianhydride represented by formula (AN-7)] In formula (AN-7), X ¹¹ is a single bond or -CH ₂ -.

Examples of the tetracarboxylic dianhydride represented by formula (AN-7) include compounds represented by the following formula (AN-7-1) and formula (AN-7-2).

[Tetracarboxylic dianhydride represented by formula (AN-8)] In formula (AN-8), X ¹¹ is a single bond or -CH ₂ -. R ¹² is a hydrogen atom, methyl, ethyl or phenyl. Ring A ¹² is a cyclohexane ring or a cyclohexene ring.

Examples of the tetracarboxylic dianhydride represented by formula (AN-8) include compounds represented by the following formula (AN-8-1) and formula (AN-8-2).

[Tetracarboxylic dianhydride represented by formula (AN-9)] In formula (AN-9), r is independently 0 or 1.

Examples of the tetracarboxylic dianhydride represented by formula (AN-9) include compounds represented by the following formulas (AN-9-1) to formula (AN-9-3).

[Tetracarboxylic dianhydride represented by formula (AN-10-1) and formula (AN-10-2)]

[Tetracarboxylic dianhydride represented by formula (AN-11)] In formula (AN-11), ring A ¹¹ is independently a cyclohexane ring or a benzene ring.

Examples of the tetracarboxylic dianhydride represented by formula (AN-11) include compounds represented by the following formulas (AN-11-1) to formula (AN-11-3).

[Tetracarboxylic dianhydride represented by formula (AN-12)] In formula (AN-12), ring A ¹¹ is independently a cyclohexane ring or a benzene ring.

Examples of the tetracarboxylic dianhydride represented by formula (AN-12) include compounds represented by the following formulas (AN-12-1) to formula (AN-12-3).

[Tetracarboxylic dianhydride represented by formula (AN-15)] In Formula (AN-15), w is an integer from 1 to 10.

Examples of the tetracarboxylic dianhydride represented by formula (AN-15) include compounds represented by the following formulas (AN-15-1) to formula (AN-15-3).

[Tetracarboxylic dianhydride represented by formula (AN-16-1) to formula (AN-16-19)] Examples of tetracarboxylic dianhydride other than the above include the following formula (AN-16-1) ~Compounds represented by formula (AN-16-19).

Among the tetracarboxylic dianhydrides, suitable materials for improving various characteristics of the liquid crystal alignment film described below will be described. When emphasis is placed on further improving the alignment of liquid crystal, it is more preferred to be represented by formula (AN-1-2), formula (AN-4-17), formula (AN-4-21) or formula (AN-4-29). In the compound represented by the formula (AN-1-2), m=4 to 8 is preferred, and in the formula (AN-4-17), m=4 to 8 is preferred.

When emphasis is placed on improving the transmittance of the liquid crystal display element, formula (AN-1-1), formula (AN-1-2), formula (AN-2-1), and formula (AN-3-1) are preferred. , formula (AN-4-17), formula (AN-4-30), formula (AN-5-1), formula (AN-7-2), formula (AN-10-1), formula (AN- 16-3) or a compound represented by formula (AN-16-4), wherein in formula (AN-1-2), m=4 or 8 is preferred, and in formula (AN-4-17), m=4 or 8 is preferred. m=4-8, more preferably m=8.

When emphasis is placed on improving the VHR of the liquid crystal display element, formula (AN-1-1), formula (AN-1-2), formula (AN-3-1), formula (AN-4-5), Formula (AN-4-17), Formula (AN-4-30), Formula (AN-7-2), Formula (AN-10-1), Formula (AN-16-3), Formula (AN-16 -4), the compound represented by formula (AN-16-17) or formula (AN-2-1), in formula (AN-1-2), preferably m=4 or 8, formula (AN-4- 17), m=4 or 8 is preferred, and m=8 is more preferred.

As one method of preventing burn marks, it is effective to reduce the volume resistance value of the liquid crystal alignment film to increase the relaxation speed of the residual charge (residual direct current (DC)) in the liquid crystal alignment film. When the purpose is taken seriously, formula (AN-1-13), formula (AN-3-2), formula (AN-4-21), formula (AN-4-29) or formula (AN -11-3) Compounds represented.

＜Other diamines＞ Diamines other than the compounds represented by formula (1), formula (2) or formula (3) used as raw materials for the polymer of the present invention can be selected from known diamines without limitation.

Diamines can be divided into two types based on their structure. That is, a diamine having a side chain group that branches from the main chain when the skeleton connecting two amino groups is regarded as a main chain and a diamine not having a side chain group. In the following description, the diamine having such a side chain group may be called a side chain diamine. Moreover, such a diamine which does not have a side chain group is sometimes called a non-side chain diamine. The side chain group has the effect of increasing the pretilt angle. By properly using the non-side chain diamine and the side chain diamine separately, it is possible to respond to the respective required pretilt angles.

It is preferable to use a side chain type diamine together to the extent which does not impair the characteristics of this invention. In addition, it is preferable to select and use a side chain type diamine and a non-side chain type diamine for the purpose of improving characteristics, such as vertical alignment with respect to a liquid crystal, VHR, and afterimage characteristics.

The following formula (DI-1) to formula (DI-16) show known diamines having no side chain. In the formula (DI-1), G ²⁰ is -CH ₂ - or a group represented by the formula (DI-1-a). When G ²⁰ is -CH ₂ -, at least one of the m -CH ₂ - may be substituted with -NH- or -O-, and at least one hydrogen atom of the m -CH ₂ - may be substituted with a hydroxyl group or a methyl group. m is an integer from 1 to 12. When m in the formula (DI-1) is 2 or more, the plurality of G ²⁰ may be the same as each other or may be different. Among them, when G ²⁰ is formula (DI-1-a), m is 1. In the formula (DI-1-a), v is an integer from 1 to 6 independently.

In formula (DI-3), formula (DI-6) and formula (DI-7), G ²¹ is a single bond, -NH-, -NCH ₃ -, -O-, -S-, -SS-, - SO ₂ -, -CO-, -COO-, -CONCH ₃ -, -CONH-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -(CH ₂ ) _m -, -O- (CH ₂ ) _m -O-, -N(CH ₃ )-(CH ₂ ) _k -N(CH ₃ )-, -(OC ₂ H ₄ ) _m -O-, -O-CH ₂ -C(CF ₃ ) ₂ -CH ₂ -O-, -O-CO-(CH ₂ ) _m -CO-O-, -CO-O-(CH ₂ ) _m -O-CO-, -(CH ₂ ) _m -NH -(CH ₂ ) _m -, -CO-(CH ₂ ) _k -NH-(CH ₂ ) _k -, -(NH-(CH ₂ ) _m ) _k -NH-, -CO-C ₃ H ₆ -( NH-C ₃ H ₆ ) _n -CO- or -S-(CH ₂ ) _m -S-, m is independently an integer from 1 to 12, k is an integer from 1 to 5, and n is 1 or 2. In Formula (DI-4), s is independently an integer from 0 to 2.

In formula (DI-5), G ³³ is a single bond, -NH-, -NCH ₃ -, -O-, -S-, -SS-, -SO ₂ -, -CO-, -COO-, -CONCH ₃ -, -CONH-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -(CH ₂ ) _m -, -O-(CH ₂ ) _m -O-, -N(CH ₃ )-(CH ₂ ) _k -N(CH ₃ )-, -(OC ₂ H ₄ ) _m -O-, -O-CH ₂ -C(CF ₃ ) ₂ -CH ₂ -O-, -O-CO -(CH ₂ ) _m -CO-O-, -CO-O-(CH ₂ ) _m -O-CO-, -(CH ₂ ) _m -NH-(CH ₂ ) _m -, -CO-(CH ₂ ) _k -NH-(CH ₂ ) _k -, -(NH-(CH ₂ ) _m ) _k -NH-, -CO-C ₃ H ₆ -(NH-C ₃ H ₆ ) _n -CO-, -S -(CH ₂ ) _m -S-, -N(Boc)-(CH ₂ ) _e -N(Boc)-, -NH-(CH ₂ ) _e -N(Boc)-, -N(Boc)-( CH ₂ ) _e -, -(CH ₂ ) _m -N(Boc)-CONH-(CH ₂ ) _m -, -(CH ₂ ) _m -N(Boc)-(CH ₂ ) _m -, or the following formula (DI-5-a) or a base represented by the following formula (DI-5-b), m is independently an integer from 1 to 12, k is an integer from 1 to 5, e is an integer from 2 to 10, n is 1 or 2. Boc is tert-butoxycarbonyl.

In formula (DI-6) and formula (DI-7), G ²² is independently a single bond, -O-, -S-, -CO-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ - or alkylene group having 1 to 10 carbon atoms.

At least one hydrogen atom of the cyclohexane ring and the benzene ring in the formula (DI-2) to the formula (DI-7) can be replaced by -F, -Cl, an alkylene group having 1 to 3 carbon atoms, -OCH ₃ , - OH, -CF ₃ , -CO ₂ H, -CONH ₂ , -NHC ₆ H ₅ , phenyl or benzyl substituted, in formula (DI-4), at least one of the cyclohexane ring and the benzene ring The hydrogen atom may be substituted with one selected from the group of groups represented by any one of the following formulas (DI-4-a) to formula (DI-4-i). In formula (DI-5), in When G ³³ is a single bond, at least one hydrogen atom of the cyclohexane ring and benzene ring can be substituted by NHBoc or N(Boc) ₂ .

A group whose bonding position is not fixed to a carbon atom constituting a ring means that the bonding position on the ring is arbitrary. Furthermore, the bonding position of -NH ₂ on the cyclohexane ring or benzene ring is any position other than the bonding position of G ²¹ , G ²² or G ³³ . In formula (DI-4-a) and formula (DI-4-b), R ²⁰ is independently a hydrogen atom or -CH ₃ . In the formula (DI-4-f) and the formula (DI-4-g), m is each independently an integer of 0 to 12, and Boc is a tert-butoxycarbonyl group.

In the formula (DI-5-a), q is independently an integer from 0 to 6. R ⁴⁴ is a hydrogen atom, -OH, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

In formula (DI-11), r is 0 or 1. In Formulas (DI-8) to Formula (DI-11), the bonding position of -NH ₂ bonded to the ring is any position.

In formula (DI-12), R ²¹ and R ²² are each independently an alkyl group or phenyl group having 1 to 3 carbon atoms, and G ²³ is independently an alkylene group, phenyl group or meryl group having 1 to 6 carbon atoms. phenylene group substituted by a base, w is an integer from 1 to 10. In formula (DI-13), R ²³ is independently an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or -Cl, p is independently an integer of 0 to 3, and q is 0 to 4. integer. In formula (DI-14), ring B is a monocyclic heterocyclic aromatic group, and R ²⁴ is a hydrogen atom, -F, -Cl, an alkyl group having 1 to 6 carbon atoms, an alkoxy group, or an alkyl group having 2 to 1 carbon atoms. For the alkenyl or alkynyl group of 6, q is independently an integer from 0 to 4. When q is 2 or more, the plurality of R ²⁴ may be the same as each other or may be different. In formula (DI-15), ring C is a heterocyclic aromatic group or a heterocyclic aliphatic group. In the formula (DI-16), G ²⁴ is a single bond, an alkylene group having 2 to 6 carbon atoms or a 1,4-phenylene group, and r is 0 or 1. Furthermore, a group whose bonding position is not fixed to a carbon atom constituting a ring means that the bonding position on the ring is arbitrary. In Formulas (DI-13) to Formula (DI-16), the bonding position of -NH ₂ bonded to the ring is any position.

Examples of the diamine represented by the formula (DI-1) are shown in the following formula (DI-1-1) to formula (DI-1-9). In Formula (DI-1-7) and Formula (DI-1-8), k is each independently an integer of 1 to 3. In the formula (DI-1-9), v is an integer from 1 to 6 independently.

In the following formulas (DI-2-1), formula (DI-2-2), formula (DI-3-1) to formula (DI-3-3), formulas (DI-2) to formulas ( Examples of diamines represented by DI-3).

Examples of the diamine represented by the formula (DI-4) are shown in the following formula (DI-4-1) to formula (DI-4-27). In Formula (DI-4-20) and Formula (DI-4-21), m is each independently an integer from 1 to 12.

Examples of the diamine represented by the formula (DI-5) are shown in the following formula (DI-5-1) to formula (DI-5-50). In the formula (DI-5-1), m is an integer from 1 to 12.

In Formula (DI-5-12) and Formula (DI-5-13), m is an integer from 1 to 12.

In the formula (DI-5-16), v is an integer from 1 to 6.

In the formula (DI-5-30), k is an integer from 1 to 5.

In Formula (DI-5-35) ~ Formula (DI-5-37) and Formula (DI-5-39), m is independently an integer from 1 to 12. Formula (DI-5-38) and Formula ( In DI-5-39), k is independently an integer from 1 to 5, and in formula (DI-5-40), n is 1 or 2.

In formula (DI-5-42) to formula (DI-5-44), e is an integer from 2 to 10. In formula (DI-5-45), R ⁴³ is independently a hydrogen atom, -NHBoc or - N(Boc) ₂ . In formula (DI-5-42) to formula (DI-5-44), Boc is tert-butoxycarbonyl.

Examples of the diamine represented by the formula (DI-6) are shown in the following formulas (DI-6-1) to formula (DI-6-7).

Examples of the diamine represented by the formula (DI-7) are shown in the following formulas (DI-7-1) to formula (DI-7-11). In Formula (DI-7-3) and Formula (DI-7-4), m is an integer from 1 to 12, and n is independently 1 or 2.

Examples of the diamine represented by the formula (DI-8) are shown in the following formulas (DI-8-1) to formula (DI-8-4).

Examples of the diamine represented by the formula (DI-9) are shown in the following formulas (DI-9-1) to formula (DI-9-3).

Examples of the diamine represented by the formula (DI-10) are shown in the following formula (DI-10-1) and formula (DI-10-2).

Examples of the diamine represented by the formula (DI-11) are shown in the following formulas (DI-11-1) to formula (DI-11-3).

Examples of the diamine represented by the formula (DI-12) are shown in the following formula (DI-12-1).

Examples of the diamine represented by the formula (DI-13) are shown in the following formula (DI-13-1) to formula (DI-13-13).

Examples of the diamine represented by the formula (DI-14) are shown in the following formulas (DI-14-1) to formula (DI-14-9).

Examples of the diamine represented by the formula (DI-15) are shown in the following formula (DI-15-1) to formula (DI-15-12).

Examples of the diamine represented by the formula (DI-16) are shown in the following formula (DI-16-1).

Next, dihydrazine used as a raw material for the polymer of the present invention will be described. Examples of known dihydrazide having no side chain include compounds represented by any one of the following formulas (DIH-1) to formula (DIH-3). In the formula (DIH-1), G ²⁵ is a single bond, an alkylene group with 1 to 20 carbon atoms, -CO-, -O-, -S-, -SO ₂ -, -C(CH ₃ ) ₂ - or -C(CF ₃ ) ₂ -. In the formula (DIH-2), ring D is a cyclohexane ring, benzene ring or naphthalene ring, and at least one hydrogen atom of the said group can be substituted by a methyl group, an ethyl group or a phenyl group. In formula (DIH-3), ring E is independently a cyclohexane ring or a benzene ring, and at least one hydrogen atom of the said group may be substituted by a methyl group, an ethyl group or a phenyl group. Multiple rings E may be the same as each other or different. Y is a single bond, an alkylene group having 1 to 20 carbon atoms, -CO-, -O-, -S-, -SO ₂ -, -C(CH ₃ ) ₂ - or -C(CF ₃ ) ₂ -. In formula (DIH-2) and formula (DIH-3), the bonding position of -CONHNH ₂ bonded to the ring is an arbitrary position.

In the following formula (DIH-1-1), formula (DIH-1-2), formula (DIH-2-1) ~ formula (DIH-2-3), formula (DIH-3-1) ~ formula ( Examples of compounds represented by any one of formula (DIH-1) to formula (DIH-3) are shown in DIH-3-6). In the formula (DIH-1-2), m is an integer from 1 to 12.

Diamines suitable for the purpose of increasing the pretilt angle will be described. The compound represented by formula (1), formula (2) or formula (3) used as a raw material for the polymer of the present invention can be suitably used in a liquid crystal alignment agent used in a lateral electric field type liquid crystal display element. However, It can also be used together with a diamine as described below to increase the pretilt angle. Examples of diamines suitable for the purpose of increasing the pretilt angle and having side chain groups include formulas (DI-31) to formula (DI-35) and formulas (DI-36-1) to formula (DI-36-8). ) diamine represented by any one of.

In formula (DI-31), G ²⁶ is a single bond, -O-, -COO-, -OCO-, -CO-, -CONH-, -CH ₂ O-, -OCH ₂ -, -CF ₂ O- , -OCF ₂ - or -(CH ₂ ) _ma -, ma is an integer from 1 to 12. Preferred examples of G ²⁶ are a single bond, -O-, -COO-, -OCO-, -CH ₂ O- or an alkylene group having 1 to 3 carbon atoms, and particularly preferred examples are a single bond, -O-, - COO-, -OCO-, -CH ₂ O-, -CH ₂ - or -CH ₂ CH ₂ -. R ²⁵ is an alkyl group having 3 to 30 carbon atoms, a phenyl group, a group having a steroid skeleton, or a group represented by the following formula (DI-31-a). In the alkyl group, at least one hydrogen atom may be substituted by -F, and at least one -CH ₂ - may be substituted by -O-, -CH=CH- or -C≡C-. The hydrogen atom of the phenyl group can be -F, -CH ₃ , -OCH ₃ , -OCH ₂ F, -OCHF ₂ , -OCF ₃ , an alkyl group with 3 to 30 carbon atoms or an alkoxy group with 3 to 30 carbon atoms. base substitution. The bonding position of -NH ₂ bonded to the benzene ring means any position on the ring, and the bonding position is preferably meta-position or para-position. That is, when the bonding position of the group "R ²⁵ -G ²⁶ -" is the 1st position, the two bonding positions are preferably the 3rd position and the 5th position or the 2nd position and the 5th position.

In the formula (DI-31-a), G ²⁷ , G ²⁸ and G ²⁹ are bonding groups, which are each independently a single bond or an alkylene group with 1 to 12 carbon atoms. More than one of the alkylene groups -CH ₂ - may be substituted by -O-, -COO-, -OCO-, -CONH- or -CH=CH-. Ring B ²¹ , Ring B ²² , Ring B ²³ and Ring B ²⁴ are independently 1,4-phenylene, 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, Pyrimidine-2,5-diyl, pyridine-2,5-diyl, naphthalene-1,5-diyl, naphthalene-2,7-diyl or anthracene-9,10-diyl, ring B ²¹ , ring In B ²² , ring B ²³ and ring B ²⁴ , at least one hydrogen atom may be substituted by -F or -CH ₃ , s, t and u are each independently an integer from 0 to 2, and their total is 1 to 5. When s, t or u is 2, the two bonding groups in each bracket may be the same or different, and the two rings may be the same or different. R ²⁶ is a hydrogen atom, -F, -OH, an alkyl group having 1 to 30 carbon atoms, a fluorine-substituted alkyl group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, -CN, -OCH ₂ F, -OCHF ₂ or -OCF ₃ , at least one -CH ₂ - of the alkyl group having 1 to 30 carbon atoms may be substituted with a divalent group represented by the following formula (DI-31-b). In formula (DI-31-b), R ²⁷ and R ²⁸ are each independently an alkyl group having 1 to 3 carbon atoms, and v is an integer of 1 to 6. Preferable examples of R ²⁶ are an alkyl group having 1 to 30 carbon atoms or an alkoxy group having 1 to 30 carbon atoms.

In formula (DI-32) and formula (DI-33), G ³⁰ is independently a single bond, -CO- or -CH ₂ -, R ²⁹ is independently a hydrogen atom or -CH ₃ , R ³⁰ is a hydrogen atom, Alkyl group having 1 to 20 carbon atoms or alkenyl group having 2 to 20 carbon atoms. At least one hydrogen atom of the benzene ring in formula (DI-33) may be substituted with an alkyl group or phenyl group having 1 to 20 carbon atoms. Furthermore, a group whose bonding position is not fixed to any carbon atom constituting the ring means that the bonding position on the ring is arbitrary. Preferably, one of the two groups "-phenylene-G ³⁰ -O-" in the formula (DI-32) is bonded to the 3-position of the steroid core, and the other is bonded to the 6-position of the steroid core. The bonding positions of the two groups "-phenylene-G ³⁰ -O-" in the formula (DI-33) on the benzene ring are preferably the bonding positions relative to the steroid core, which are meta or para position respectively. In Formula (DI-32) and Formula (DI-33), -NH ₂ bonded to the benzene ring means that the bonding position on the ring is arbitrary.

In formula (DI-34) and formula (DI-35), G ³¹ is independently -O- or an alkylene group having 1 to 6 carbon atoms, and G ³² is a single bond or an alkylene group having 1 to 3 carbon atoms. R ³¹ is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and at least one -CH ₂ - of the alkyl group may be substituted by -O-, -CH=CH- or -C≡C-. R ³² is an alkyl group having 6 to 22 carbon atoms, and R ³³ is a hydrogen atom or an alkyl group having 1 to 22 carbon atoms. Ring B ²⁵ is 1,4-phenylene or 1,4-cyclohexylene, and r is 0 or 1. Furthermore, -NH ₂ bonded to the benzene ring means that the bonding position on the ring is arbitrary, and preferably is meta or para position independently with respect to the bonding position of G ³¹ .

Examples of compounds represented by formula (DI-31) are shown in the following formulas (DI-31-1) to formula (DI-31-55).

In formula (DI-31-1) to formula (DI-31-11), R ³⁴ is an alkyl group having 1 to 30 carbon atoms or an alkoxy group having 1 to 30 carbon atoms, and is preferably an alkyl group having 5 to 25 carbon atoms. group or alkoxy group having 5 to 25 carbon atoms. R ³⁵ is an alkyl group having 1 to 30 carbon atoms or an alkoxy group having 1 to 30 carbon atoms, and is preferably an alkyl group having 3 to 25 carbon atoms or an alkoxy group having 3 to 25 carbon atoms.

In formula (DI-31-12) to formula (DI-31-17), R ³⁶ is an alkyl group having 4 to 30 carbon atoms, preferably an alkyl group having 6 to 25 carbon atoms. R ³⁷ is an alkyl group having 6 to 30 carbon atoms, preferably an alkyl group having 8 to 25 carbon atoms.

In formula (DI-31-18) to formula (DI-31-43), R ³⁸ is an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms, preferably an alkyl group having 3 to 20 carbon atoms. group or alkoxy group having 3 to 20 carbon atoms. R ³⁹ is a hydrogen atom, -F, an alkyl group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, -CN, -OCH ₂ F, -OCHF ₂ or -OCF ₃ , and preferably has 3 to 30 carbon atoms. 25 alkyl group or alkoxy group having 3 to 25 carbon atoms. Moreover, G ³³ is an alkylene group having 1 to 20 carbon atoms.

Examples of compounds represented by formula (DI-32) are shown in the following formulas (DI-32-1) to formula (DI-32-4).

Examples of compounds represented by formula (DI-33) are shown in the following formulas (DI-33-1) to formula (DI-33-8).

Examples of compounds represented by formula (DI-34) are shown in the following formulas (DI-34-1) to formula (DI-34-12). In formula (DI-34-1) to formula (DI-34-12), R ⁴⁰ is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and, R ⁴¹ is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.

Examples of compounds represented by formula (DI-35) are shown in the following formulas (DI-35-1) to formula (DI-35-3). In formula (DI-35-1) to formula (DI-35-3), R ³⁷ is an alkyl group having 6 to 22 carbon atoms, and R ⁴¹ is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.

Compounds represented by formula (DI-36-1) to formula (DI-36-8) are shown below. In formula (DI-36-1) to formula (DI-36-8), R ⁴² is each independently an alkyl group having 3 to 30 carbon atoms.

Among the diamines, suitable materials for improving various characteristics of the liquid crystal alignment film described below will be described. When emphasis is placed on improving liquid crystal alignment, it is preferable to use formula (DI-1-3), formula (DI-5-1), formula (DI-5-5), formula (DI-5-9), and formula (DI-5-12), formula (DI-5-13), formula (DI-5-29), formula (DI-6-7), formula (DI-7-3) or formula (DI-11- 2) The compound represented. In the formula (DI-5-1), m=2 to 8 is preferred, and m=4 to 8 is more preferred. In the formula (DI-5-12), m=2 to 6 is preferred, and m=5 is more preferred. In the formula (DI-5-13), m=1 or 2 is preferred, and m=1 is more preferred.

When emphasis is placed on improving transmittance, it is preferable to use formula (DI-1-3), formula (DI-2-1), formula (DI-5-1), formula (DI-5-5), formula ( DI-5-24) or diamine represented by formula (DI-7-3), more preferably a compound represented by formula (DI-2-1). In the formula (DI-5-1), m=2 to 8 is preferred, and m=8 is more preferred. In formula (DI-7-3), m=2 or 3 and n=1 or 2 are preferred, and m=3 and n=1 are more preferred.

When emphasis is placed on improving the VHR of the liquid crystal display element, it is preferable to use formula (DI-2-1), formula (DI-4-1), formula (DI-4-2), and formula (DI-4-10) , formula (DI-4-15), formula (DI-4-22), formula (DI-5-1), formula (DI-5-28), formula (DI-5-30) or formula (DI- The compound represented by 13-1) is more preferably a diamine represented by formula (DI-2-1), formula (DI-5-1) or formula (DI-13-1). In the formula (DI-5-1), m=1 is preferred. In the formula (DI-5-30), k=2 is preferred.

As one method of preventing burn marks, it is effective to reduce the volume resistance value of the liquid crystal alignment film to increase the relaxation speed of the residual charge (residual DC) in the liquid crystal alignment film. When the above purpose is taken seriously, it is preferable to use formula (DI-4-1), formula (DI-4-2), formula (DI-4-10), formula (DI-4-15), formula ( DI-5-1), type (DI-5-12), type (DI-5-13), type (DI-5-28), type (DI-4-20), type (DI-4-21 ), a compound represented by formula (DI-7-12) or formula (DI-16-1), more preferably a compound represented by formula (DI-4-1), formula (DI-5-1) or formula (DI-5 -13) Compounds represented. In the formula (DI-5-1), m=2 to 8 is preferred, and m=4 to 8 is more preferred. In the formula (DI-5-12), m=2 to 6 is preferred, and m=5 is more preferred. In the formula (DI-5-13), m=1 or 2 is preferred, and m=1 is more preferred. In the formula (DI-7-12), m=3 or 4 is preferred, and m=4 is more preferred.

In the raw material composition used as a raw material for the polymer of the present invention, part of the diamines may be substituted with at least one selected from the group consisting of monoamines and monohydrazines. The ratio of substitution is preferably in a range in which the ratio of at least one selected from the group consisting of monoamines and monohydrazines relative to the diamines is 40 mol% or less. Such substitution can cause the termination of the polymerization reaction during the production of polyamic acid and can inhibit further progress of the polymerization reaction. Therefore, through such substitution, the molecular weight of the obtained polymer (polyamide or its derivatives) can be easily controlled, and for example, the coating characteristics of the liquid crystal alignment agent can be improved without impairing the effects of the present invention. As long as the effect of the present invention is not impaired, the number of diamines substituted by monoamine or monohydrazine may be one type or two or more types. Examples of the monoamine include: aniline, 4-hydroxyaniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-decylamine Monoamine, n-dodecaamine, n-tridecaamine, n-tetradecaamine, n-pentadecaamine, n-hexadecylamine, n-heptadecanamine, n-octadecylamine, n-eicosanamine, p-aminophenyltrimethoxy silane and 3-aminopropyltriethoxysilane.

When the polymer of the present invention is polyamic acid or a derivative thereof, the raw material composition may further contain a monoisocyanate compound as a monomer. By including a monoisocyanate compound as a monomer, the terminals of the obtained polyamide or its derivative are modified and the molecular weight is adjusted. By using the terminal-modified polyamide or its derivatives, for example, the coating characteristics of the liquid crystal alignment agent can be improved without impairing the effects of the present invention. From this viewpoint, the content of the monoisocyanate compound in the monomer is preferably 1 to 10 mol% relative to the total amount of diamine and tetracarboxylic dianhydride in the monomer. Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.

In addition to the polymer (K) and polymer (L) of the present invention, the liquid crystal alignment agent of the present invention may also contain polymers other than those of the present invention. In addition, in this specification, a liquid crystal alignment agent that mixes two or more of the polymers may be called a blended liquid crystal alignment agent. Blended liquid crystal alignment agents are used when VHR reliability or other electrical properties are particularly important.

The polymer other than the present invention used in the blended liquid crystal alignment agent is preferably at least one of polyamic acid and polyamic acid derivatives. As polymers other than those of the present invention, regarding polyamic acid and polyamic acid derivatives, except that compounds represented by formula (1) and compounds having a photoreactive structure are not included as raw material compositions, refer to the above-mentioned polymers. Description of the polymers of the present invention.

When two-component polymers are used, for example, one may select a polymer that has excellent performance in liquid crystal alignment ability, and the other may select a polymer that has excellent properties in improving the electrical characteristics of a liquid crystal display element. A polymer with excellent performance is suitable for obtaining an alignment agent with a good balance between liquid crystal alignment and electrical properties.

The liquid crystal alignment agent of the present invention is a blended liquid crystal alignment agent containing at least two polymers, polymer (K) and polymer (L). The polymer (K) is a polymer having a photoreactive structure and excellent liquid crystal alignment ability. The polymer (L) has a diphenylamine structure derived from the compound represented by formula (1) and has excellent performance for improving the electrical characteristics of a liquid crystal display element. By preparing a blended liquid crystal alignment agent of the polymer (K) and the polymer (L), an alignment agent with a good balance between liquid crystal alignment and electrical properties can be obtained.

The ratio of the polymer (K) to the total amount of the polymer (K) and the polymer (L) is preferably 5% by weight to 60% by weight, and more preferably 20% by weight to 50% by weight.

In a liquid crystal alignment agent containing a two-component polymer, it is known that a polymer with a small surface energy segregates in the upper layer, and a polymer with a large surface energy segregates in the lower layer (phase separation). By appropriately changing the structure or molecular weight of each polymer and adjusting its surface energy, one of the polymers can be segregated in the upper layer of the film and the other polymer can be segregated in the lower layer of the film. That is, by adjusting the surface energy of the polymer, the liquid crystal alignment agent obtained by dissolving these polymers in a solvent is applied to a substrate and pre-dried to form a thin film as described later. The polymer with excellent alignment ability is segregated in the upper layer of the film, and the polymer with excellent ability to improve the electrical properties of the liquid crystal display element is segregated in the lower layer of the film, thereby obtaining the desired liquid crystal alignment film with a good balance between liquid crystal alignment and electrical properties. By confirming that the surface energy of the liquid crystal alignment film formed in this manner is the same as or equivalent to the surface energy of a film formed of a polymer intended to segregate in the upper layer, it can be confirmed that the desired liquid crystal alignment film is obtained.

An example of a method for achieving layer separation is to reduce the molecular weight of a polymer intended to be segregated in the upper layer.

In a liquid crystal alignment agent containing a mixture of polymers, layer separation can also be achieved by using polyimide as the polymer to be segregated in the upper layer.

In the present invention, the compound represented by formula (1) is preferably used as a raw material for a polymer segregated in the lower layer of the film.

In the present invention, the compound having a photoreactive structure is preferably used as a raw material for the polymer segregated in the upper layer of the film.

As the tetracarboxylic dianhydride for synthesizing the polyamic acid or its derivatives segregated in the upper layer of the film and the polyamic acid or its derivatives segregated in the lower layer of the film, the tetracarboxylic dianhydride can be obtained without limitation. Select from the well-known tetracarboxylic dianhydrides exemplified above.

The tetracarboxylic dianhydride used to synthesize the polyamic acid or its derivatives segregated in the upper layer of the film is preferably formula (AN-1-1), formula (AN-1-2), formula (AN-2-1 ), a compound represented by formula (AN-3-1), formula (AN-4-5), formula (AN-4-17) or formula (AN-4-21), more preferably a compound represented by formula (AN-4 -17) or formula (AN-4-21). In the formula (AN-4-17), m=4 to 8 is preferred.

Tetracarboxylic dianhydride for synthesizing polyamic acid or its derivatives segregated in the lower layer of the film is preferably a formula (AN-1-1), a formula (AN-1-13), or a formula (AN-2 -1), a compound represented by formula (AN-3-2) or formula (AN-4-21), more preferably a compound represented by formula (AN-1-1), formula (AN-2-1) or formula (AN -3-2).

The tetracarboxylic dianhydride used to synthesize the polyamic acid or its derivative segregated in the lower layer of the film preferably contains 10 mol % or more of aromatic tetracarboxylic dianhydride in the total amount of tetracarboxylic dianhydride, More preferably, it contains 30 mol% or more.

Formula (1), Formula (2) or Formula (3) for synthesizing polyamic acid or its derivatives segregated in the upper layer of the film and polyamic acid or its derivatives segregated in the lower layer of the film. Diamines other than the compounds can be selected without limitation from the above-exemplified known diamines.

As diamines for synthesizing polyamic acid or its derivatives segregated in the upper layer of the film, it is preferable to use formula (DI-4-1), formula (DI-4-13), formula (DI-4- 15), compounds represented by formula (DI-5-1), formula (DI-7-3) or formula (DI-13-1). Among these, it is more preferable to use the compound represented by formula (DI-4-13), formula (DI-4-15), formula (DI-5-1), or formula (DI-13-1). In the formula (DI-5-1), m=4 to 8 is preferred. In the formula (DI-7-3), m=3 and n=1 are preferred.

Preferred diamines for synthesizing polyamic acid or its derivatives segregated in the lower layer of the film are formula (DI-4-1), formula (DI-4-2), and formula (DI-4-10 ), formula (DI-4-18), formula (DI-4-19), formula (DI-5-1), formula (DI-5-9), formula (DI-5-28), formula (DI -5-30), a compound represented by formula (DI-13-1) or formula (DIH-1-2). In formula (DI-5-1), a compound in which m=1 or 2 is preferred, and in formula (DI-5-30), a compound in which k=2 is preferred. Among them, formula (DI-4-1), formula (DI-4-18), formula (DI-4-19), formula (DI-5-9), formula (DI-13-1) or Compounds represented by formula (DIH-1-2).

With respect to all diamines, the diamines used to synthesize the polyamic acid or its derivatives segregated in the lower layer of the film preferably contain 30 mol% or more of an aromatic diamine and an aromatic dihydrazide. At least one of the groups includes more preferably 50 mol% or more.

In addition to the polymer (K) and polymer (L) of the present invention, the liquid crystal alignment agent of the present invention may also contain polymers other than those of the present invention. Examples of the polymer other than the present invention include polyamic acid, polyamic acid derivatives, acrylic polymers, siloxane polymers, etc., and preferably one or more of polyamic acid and polyamic acid derivatives. . As polymers other than the present invention, with regard to polyamic acid and polyamic acid derivatives, except for the compounds represented by formula (1) or compounds having a photoreactive structure that are not included in the raw material composition, refer to the above-mentioned polymers. Description of the polymers of the present invention.

In addition, the liquid crystal alignment agent of the present invention may further contain a solvent from the viewpoint of the coating properties of the liquid crystal alignment agent or the adjustment of the concentration of the polyamide or its derivatives. The solvent can be used without particular limitation as long as it has the ability to dissolve the polymer component. The solvent includes a wide range of solvents commonly used in the production steps or uses of polymer components such as polyamide acid and soluble polyimide, and can be appropriately selected according to the purpose of use. The solvent may be one type or a mixture of two or more solvents.

Examples of the solvent include solvophiles of the polyamic acid or derivatives thereof, or other solvents for the purpose of improving coatability.

Examples of aprotic polar organic solvents that are solvent-philic with respect to polyamic acid or its derivatives include: N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and dimethylimidazolidinone , N-methylcaprolactam, N-methylpropionamide, N,N-dimethylacetamide, dimethylsyanoxide, N,N-dimethylformamide, N,N- Diethylformamide, diethylacetamide, N,N-dimethylisobutylamide, γ-butyrolactone and γ-valerolactone, etc. Among these solvents, N-methyl-2-pyrrolidone, dimethylimidazolidinone, γ-butyrolactone or γ-valerolactone is preferred.

Examples of other solvents for the purpose of improving coating properties include ethylene glycol monoalkyl ethers such as ethylene glycol monobutyl ether and ethylene glycol monotert-butyl ether, and diethylene glycol monoethyl ether and the like. Diethylene glycol dialkyl ethers such as ethylene glycol monoalkyl ether, diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, and diethylene glycol butyl methyl ether. Examples include: propylene glycol monomethyl ether, propylene glycol monoalkyl ether such as 1-butoxy-2-propanol, dipropylene glycol monoalkyl ether such as dipropylene glycol monomethyl ether, triethylene glycol monoalkyl ether, butyl solvent Fiber acetate, phenylacetate and these acetate esters and other ester compounds. Furthermore, examples include dialkyl malonate such as diethyl malonate, alkyl lactate, diisobutyl ketone, diacetone alcohol, 3-methyl-3-methoxybutanol, 4- Methyl-2-pentanol, diisobutylcarbinol, tetralin and isophorone.

Among these solvents, diisobutyl ketone, 4-methyl-2-pentanol, diisobutylmethanol, ethylene glycol monobutyl ether, ethylene glycol monotert-butyl ether, and diethylene glycol monoethyl ether are preferred. , diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, diethylene glycol butyl methyl ether, 1-butoxy-2-propanol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether or butyl cellosolve agent acetate.

The solid content concentration in the liquid crystal alignment agent of the present invention is not particularly limited, as long as the most appropriate value is selected in combination with the following various coating methods. Generally, in order to suppress unevenness, pinholes, etc. during coating, the content is preferably 0.1% to 30% by weight, and more preferably 1% to 10% by weight relative to the weight of the varnish.

The preferred range of the viscosity of the liquid crystal alignment agent of the present invention varies depending on the coating method, the concentration of polyamic acid or its derivatives, the type of polyamic acid or its derivatives used, and the type and ratio of the solvent. For example, when coating is performed using a printer, the range is 5 mPa·s to 100 mPa·s (more preferably 10 mPa·s to 80 mPa·s). If it is 5 mPa·s or more, it is easy to obtain a sufficient film thickness; if it is 100 mPa·s or less, printing unevenness is easily suppressed. When coating is performed by spin coating, 5 mPa·s to 200 mPa·s (more preferably 10 mPa·s to 100 mPa·s) is suitable. When applying using an inkjet coating device, 5 mPa·s to 50 mPa·s (more preferably 5 mPa·s to 20 mPa·s) is suitable. The viscosity of the liquid crystal alignment agent can be measured by a rotational viscometer, for example, a rotational viscometer (TVE-20L viscometer manufactured by Toki Sangyo Co., Ltd.) (measurement temperature: 25°C).

The liquid crystal alignment agent of the present invention may also contain various additives. In order to improve various characteristics of the alignment film, various additives can be selected and used according to various purposes. Examples are shown below.

＜Alkenyl-substituted nadicamide compounds＞ For example, for the purpose of stabilizing the electrical characteristics of the liquid crystal display element for a long period of time, the liquid crystal alignment agent of the present invention may further contain an alkenyl-substituted nadicamide compound. One type of alkenyl-substituted nadicamide compound may be used, or two or more types may be used in combination. For the above purpose, the content of the alkenyl-substituted nadicamide compound is preferably 1% to 50% by weight, more preferably 1% to 30% by weight, relative to the polyamic acid or its derivatives. More preferably, it is 1 to 20% by weight. The alkenyl-substituted nadicamide compound is preferably a compound soluble in a solvent that dissolves the polyamic acid or its derivative used in the present invention. Preferred alkenyl-substituted nadicamide compounds include alkenyl-substituted sodium disclosed in Japanese Patent Laid-Open No. 2008-096979, Japanese Patent Laid-Open No. 2009-109987, and Japanese Patent Laid-Open No. 2013-242526. Dickinium compounds. Particularly preferred alkenyl-substituted nadicamide compounds include bis{4-(allylbicyclo[2.2.1]hept-5-en-2,3-dicarboxylimide)phenyl} Methane, N,N'-isoxylylene-bis(allylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxylimide) or N,N'-hexamethylene -Bis(allylbicyclo[2.2.1]hept-5-ene-2,3-dicarboxylimide).

＜Compounds having radically polymerizable unsaturated double bonds＞ For example, for the purpose of stabilizing the electrical characteristics of a liquid crystal display element for a long period of time, the liquid crystal alignment agent of the present invention may further contain a compound having a radically polymerizable unsaturated double bond. The compound having a radically polymerizable unsaturated double bond may be one compound or two or more compounds. In addition, the alkenyl-substituted nadicamide compound is not included in the compound having a radically polymerizable unsaturated double bond. Among compounds having radically polymerizable unsaturated double bonds, preferred compounds include N,N'-methylenebisacrylamide and N,N'-dihydroxyethylidene-bisacrylamide. , ethylidene bisacrylate, 4,4'-methylenebis(N,N-dihydroxyethylidene acrylate aniline), triallyl cyanurate; and Japanese Patent Application Publication No. 2009-109987 , a compound having a radically polymerizable unsaturated double bond disclosed in Japanese Patent Application Laid-Open No. 2013-242526, International Publication No. 2014/119682, and International Publication No. 2015/152014. For the above purpose, the content of the compound having a radically polymerizable unsaturated double bond is preferably 1 to 50% by weight, and more preferably 1 to 30% by weight relative to polyamide or its derivatives. %.

＜Oxazine compounds＞ For example, for the purpose of stabilizing the electrical characteristics of the liquid crystal display element for a long period of time, the liquid crystal alignment agent of the present invention may further contain an oxazine compound. The oxazine compound may be one compound or two or more compounds. For the above purpose, the content of the oxazine compound is preferably 0.1% to 50% by weight, more preferably 1% to 40% by weight, and still more preferably 1% by weight relative to the polyamide or its derivatives. ~20% by weight.

The oxazine compound is preferably an oxazine compound that is soluble in a solvent that dissolves polyamic acid or a derivative thereof and has ring-opening polymerizability. Preferred oxazine compounds include those represented by formula (OX-3-1), formula (OX-3-9), or formula (OX-3-10); and Japanese Patent Laid-Open No. 2007-286597 Oxazine compounds disclosed in Japanese Patent Application Publication No. 2013-242526.

＜Oxazoline compounds＞ For example, for the purpose of stabilizing the electrical characteristics of the liquid crystal display element for a long period of time, the liquid crystal alignment agent of the present invention may further contain an oxazoline compound. An oxazoline compound is a compound having an oxazoline structure. The oxazoline compound may be one type of compound or two or more types of compounds. For the above purpose, the content of the oxazoline compound is preferably 0.1% to 50% by weight, more preferably 1% to 40% by weight, and even more preferably 1% by weight relative to the polyamic acid or its derivatives. %~20% by weight. Preferred oxazoline compounds include those disclosed in Japanese Patent Application Laid-Open No. 2010-054872 and Japanese Patent Application Laid-Open No. 2013-242526. More preferred ones include 1,3-bis(4,5-dihydro-2-oxazolyl)benzene.

＜Epoxy compound＞ For example, the liquid crystal alignment agent of the present invention may further contain an epoxy compound for the purpose of stabilizing the electrical characteristics of the liquid crystal display element for a long period of time, improving the hardness of the film, or improving the adhesion with the sealant. The epoxy compound may be one compound or two or more compounds. For the above purpose, the content of the epoxy compound is preferably 0.1% to 50% by weight, more preferably 1% to 20% by weight, and still more preferably 1% by weight relative to the polyamide or its derivatives. ~10% by weight.

As the epoxy compound, various compounds having one or two or more epoxy rings in the molecule can be used. In order to achieve the purpose of increasing the hardness of the film or improving the adhesion to the sealant, a compound having two or more epoxy rings in the molecule is preferred, and a compound having three or four epoxy rings is more preferred. .

Examples of the epoxy compound include those disclosed in Japanese Patent Laid-Open No. 2009-175715, Japanese Patent Laid-Open No. 2013-242526, Japanese Patent Laid-Open No. 2016-170409, and International Publication No. 2017/217413. compound. Preferable epoxy compounds include: N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, 3-glycidoxypropyltrimethoxysilane , 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, (3,3',4,4' -Diepoxy)bicyclohexyl, 1,4-butanediol glycidyl ether, tris(2,3-epoxypropyl)isocyanurate, 1,3-bis(N,N-diglycidyl) methylaminomethyl)cyclohexane or N,N,N',N'-tetraglycidyl-m-xylylenediamine. More preferred ones include: 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane or 2-(3,4-epoxycyclohexyl) Ethyltriethoxysilane. In addition, oligomers or polymers having an epoxy ring may also be added. As the oligomer or polymer having an epoxy ring, those disclosed in Japanese Patent Application Laid-Open No. 2013-242526 can be used.

＜Silane compound＞ For example, the liquid crystal alignment agent of the present invention may further contain a silane compound for the purpose of improving the adhesiveness with the substrate and the sealant. For the above purpose, the content of the silane compound is preferably 0.1% by weight to 30% by weight, more preferably 0.5% by weight to 20% by weight, and even more preferably 0.5% by weight to 0.5% by weight relative to the polyamic acid or its derivatives. 10% by weight.

As the silane compound, silane coupling agents disclosed in Japanese Patent Laid-Open No. 2013-242526, Japanese Patent Laid-Open No. 2015-212807, Japanese Patent Laid-Open No. 2018-173545, and International Publication No. 2018/181566 can be used. . Preferred silane coupling agents include: 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl Trimethoxysilane, p-aminophenyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-isocyanatopropyl Triethoxysilane or 3-ureidopropyltriethoxysilane.

In addition to the additives described above, for the purpose of improving the strength of the alignment film or stabilizing the electrical characteristics of the liquid crystal display element for a long time, a compound having a cyclic carbonate group, a hydroxyalkylamide moiety or a compound may also be added. hydroxyl compound. Specific compounds include compounds disclosed in Japanese Patent Application Laid-Open No. 2016-118753 and International Publication No. 2017/110976. Preferable compounds include the following formulas (HD-1) to formula (HD-4). The amount of these compounds is preferably 0.5% by weight to 50% by weight, more preferably 1% by weight to 30% by weight, and even more preferably 1% by weight to 10% by weight relative to polyamide or its derivatives.

In addition, when antistatic needs to be improved, an antistatic agent can also be used, and when imidization is performed at low temperature, an imidization catalyst can also be used. Examples of the imidization catalyst include those disclosed in Japanese Patent Application Laid-Open No. 2013-242526.

＜Liquid crystal alignment film＞ Next, the liquid crystal alignment film of the present invention will be described. The liquid crystal alignment film of the present invention is formed using the liquid crystal alignment agent of the present invention. When the liquid crystal alignment agent of the present invention is used to form a liquid crystal alignment film, heating and calcination may cause an imidization reaction to form a polyimide-based liquid crystal alignment film. The liquid crystal alignment agent of the present invention is suitable for use in photo-alignment, and the photo-alignment method can be applied in the alignment process during the formation of the liquid crystal alignment film.

Hereinafter, a method of forming a liquid crystal alignment film using the liquid crystal alignment agent for photo alignment of the present invention will be described.

The liquid crystal alignment film of the present invention can be obtained by a common method of producing a liquid crystal alignment film from a liquid crystal alignment agent for photo alignment. For example, the liquid crystal alignment film of the present invention can be obtained by following the steps of forming a coating film of the liquid crystal alignment agent for photo-alignment of the present invention, heating and drying the coating film to form a film of the liquid crystal alignment agent, and treating the liquid crystal The step of irradiating the film of the alignment agent with light to impart anisotropy and the step of heating and calcining the film of the liquid crystal alignment agent to which anisotropy has been imparted.

The coating film can be formed by applying the liquid crystal alignment agent of the present invention to a substrate in a liquid crystal display element in the same manner as a normal liquid crystal alignment film. The substrate can be provided with electrodes such as indium tin oxide (Indium Tin Oxide, ITO), indium zinc oxide (In ₂ O ₃ -ZnO, IZO), indium gallium zinc oxide (In-Ga-ZnO ₄ , IGZO) electrodes or color electrodes. Substrates such as optical filters made of glass, silicon nitride, acrylic, polycarbonate, polyimide, etc.

As a method of applying a liquid crystal alignment agent to a substrate, generally known methods include a spinner method, a printing method, a dipping method, a dropping method, an inkjet method, and the like. These methods are equally applicable to the present invention.

In the heating and drying step, a method of heating in an oven or an infrared oven, a method of heating on a hot plate, etc. are generally known. The heating and drying step is preferably performed at a temperature within a range in which the solvent can evaporate, and more preferably is performed at a relatively low temperature relative to the temperature in the heating and calcining step. Specifically, the heating and drying temperature is preferably in the range of 30°C to 150°C, and more preferably in the range of 50°C to 120°C.

The heating and calcination step can be carried out under conditions required for polyamide acid or its derivatives to undergo an imidization reaction. Generally known methods for calcining the coating film include heat treatment in an oven or an infrared furnace, heat treatment on a hot plate, and the like. These methods are equally applicable to the present invention. Usually, it is preferable to carry out at the temperature of about 90 to 300 degreeC for 1 minute to 3 hours, More preferably, it is 120 to 280 degreeC, Still more preferably, it is 150 to 250 degreeC.

When emphasis is placed on improving the anisotropy of the film or the afterimage characteristics when producing a liquid crystal display element, it is preferable to gradually increase the temperature in the heating step. For example, the temperature can be increased stepwise while performing multiple operations at different temperatures. Heating is performed by heating and calcination, or by changing the temperature from low temperature to high temperature. In addition, two heating methods can also be combined.

When heating and calcination are performed multiple times at different temperatures, multiple heating devices set to different temperatures can be used, or one heating device can be used to sequentially change to different temperatures.

When heating and calcination are performed multiple times at different temperatures, it is preferable that the initial calcination temperature is 90°C to 180°C, and the final calcination temperature is preferably 185°C to 300°C. For example, it is preferable to heat and bake at 110°C and then heat and bake at 220°C; Heating and calcining at 150°C, then heating and calcining at 200°C; After heating and calcining at 150°C, then heating and calcining at 220°C; After heating and calcining at 150°C, at 230°C. Heating and calcining at ℃; or heating and calcining at 170℃ and then heating and calcining at 200℃. Furthermore, it is also preferable to perform heating and baking while gradually raising the temperature in increasing steps. When the heating temperature is changed to perform heating and baking in two or more stages, the heating time in each heating step is preferably 5 minutes to 30 minutes.

When baking is performed by changing the temperature from a low temperature to a high temperature, the initial temperature is preferably 90°C to 180°C. The final temperature is preferably 185°C to 300°C, more preferably 190°C to 230°C. The heating time is preferably 5 minutes to 60 minutes, more preferably 20 minutes to 60 minutes. The temperature increase rate can be set to 0.5°C/min to 40°C/min, for example. The heating rate during heating does not need to be fixed.

In the method of forming a liquid crystal alignment film of the present invention, in order to align the liquid crystal in one direction with respect to the horizontal direction and/or the vertical direction, a known photo-alignment method can be suitably used as a method of imparting anisotropy to the film.

The method for forming the liquid crystal alignment film of the present invention using the photo-alignment method will be described in detail. The liquid crystal alignment film of the present invention using the photoalignment method can be formed by irradiating light to a film after heating and drying the coating film to impart anisotropy to the film, and heating and baking the film. Alternatively, it can be formed by heating and drying the coating film, performing heating and baking, and then irradiating the film with light.

Furthermore, in order to improve the liquid crystal alignment ability of the liquid crystal alignment film, light may be irradiated while heating the coating film. The irradiation of light may be performed during the step of heating and drying the coating film or the step of heating and calcination, or may be performed between the heating and drying step and the heating and calcination step. The heating temperature when irradiating light in the heat-drying step or the heat-baking step of the coating film can refer to the description of the heat-drying step or the heat-baking step. The heating temperature when irradiating light between the heat-drying step and the heat-baking step is preferably in the range of 30°C to 150°C, more preferably in the range of 50°C to 110°C.

As the light used in the light irradiation step in the photoalignment method, for example, ultraviolet light or visible light containing light with a wavelength of 150 nm to 800 nm can be used. These lights are not particularly limited as long as they can impart liquid crystal alignment ability to the film. When a strong alignment regulating force is to be exerted on liquid crystals, polarized light is preferred, and linear polarized light is more preferred.

The irradiation amount of polarized light in the light irradiation step is preferably 0.05 J/cm ² to 10 J/cm ² , and more preferably 0.1 J/cm ² to 5 J/cm ² . In addition, the wavelength of polarized light is preferably appropriately changed according to the compound having a photoreactive structure. When using the compound represented by Formula (2), the wavelength of polarized light is preferably 200 nm to 400 nm, and more preferably 300 nm to 400 nm. When using the compound represented by formula (3), the wavelength of polarized light is preferably 150 nm to 350 nm, and more preferably 200 nm to 300 nm. The angle at which the polarized light irradiates the film surface is not particularly limited. If a strong alignment-restricting force on the liquid crystal is to be exerted, from the viewpoint of shortening the alignment treatment time, it is preferably as perpendicular to the film surface as possible. In addition, the liquid crystal alignment film of the present invention can align liquid crystal in a direction at right angles to the polarization direction of linearly polarized light by irradiating linearly polarized light.

Among the light sources used in the step of irradiating light, ultra-high-pressure mercury lamps, high-pressure mercury lamps, low-pressure mercury lamps, deep UV lamps, halogen lamps, metal halide lamps, high-power metal halide lamps, and Xenon lamp, mercury xenon lamp, excimer lamp, KrF excimer laser, fluorescent lamp, light emitting diode (LED) lamp, sodium lamp, microwave discharged electrodeless lamp, etc.

The liquid crystal alignment film of the present invention can be suitably obtained by a method further including steps other than the above-mentioned steps.

Although the liquid crystal alignment film of the present invention does not require the step of cleaning the film after baking or light irradiation with a cleaning solution, the cleaning step can be provided according to the conditions of other steps. Examples of cleaning methods using cleaning fluids include brushing, jet spray, steam cleaning, ultrasonic cleaning, and the like. These methods can be performed individually or in combination. As the cleaning fluid, you can use: pure water; or various alcohols such as methanol, ethanol, and isopropyl alcohol; aromatic hydrocarbons such as benzene, toluene, and xylene; halogen solvents such as methylene chloride; acetone, methyl ethyl ketone, etc. Ketones, etc., but are not limited to these. Of course, for these cleaning solutions, fully purified cleaning solutions with few impurities can be used. This cleaning method can also be applied to the cleaning step in the formation of the liquid crystal alignment film of the present invention.

In order to improve the liquid crystal alignment ability of the liquid crystal alignment film of the present invention, annealing treatment using heat or light can be used before and after the heating and calcination step or before and after polarized or non-polarized light irradiation. In the annealing treatment, the annealing temperature is 30°C to 180°C, preferably 50°C to 150°C, and the annealing time is preferably 1 minute to 2 hours. In addition, examples of the annealing light used in the annealing treatment include UV lamps, fluorescent lamps, LED lamps, and the like. The amount of light irradiation is preferably 0.3 J/cm ² to 10 J/cm ² .

The film thickness of the liquid crystal alignment film of the present invention is not particularly limited, but is preferably 10 nm to 300 nm, and more preferably 30 nm to 150 nm. The film thickness of the liquid crystal alignment film of the present invention can be measured by a known film thickness measuring device such as a profilometer or an ellipsometer.

The liquid crystal alignment film of the present invention is characterized by having particularly large alignment anisotropy. The magnitude of such anisotropy can be evaluated by a method using polarized IR described in Japanese Patent Application Laid-Open No. 2005-275364 and the like. In addition, it can also be evaluated by using ellipsometry. Specifically, the retardation value of the liquid crystal alignment film can be measured using a spectroscopic ellipsometer. The retardation value of the film increases in proportion to the degree of alignment of the polymer backbone.

The liquid crystal alignment film of the present invention can be suitably used for alignment control of a liquid crystal composition in a liquid crystal display element. In addition to the alignment use of liquid crystal compositions in liquid crystal display elements, it can also be used to control the alignment of liquid crystal materials in all other liquid crystal elements such as liquid crystal antennas, dimming windows, optical compensation materials, and variable phase shifters. In addition, the liquid crystal alignment film of the present invention has large anisotropy, so it can be used alone as an optical compensation material.

＜Liquid crystal display element＞ Next, the liquid crystal display element of the present invention will be described. The liquid crystal display element of the present invention is characterized by having the liquid crystal alignment film of the present invention, and can achieve high display quality due to its high voltage retention rate.

The liquid crystal display element of the present invention will be described in detail. In the present invention, in the following liquid crystal display element, the liquid crystal alignment film includes the liquid crystal alignment film of the present invention, the liquid crystal display element includes a pair of substrates arranged opposite to each other, and is formed on each of the facing surfaces of the pair of substrates. An electrode on one or both of the substrates, a liquid crystal alignment film formed on the opposing surfaces of the pair of substrates, a liquid crystal layer formed between the pair of substrates, and a pair of electrodes disposed to sandwich the opposing substrates. For polarizing films, backlights and driving devices.

The electrode is not particularly limited as long as it is formed on one side of the substrate. Examples of such electrodes include vapor-deposited films of ITO and metal. In addition, the electrode may be formed on the entire surface of one side of the substrate, or may be formed in a desired shape by patterning, for example. Examples of the desired shape of the electrode include a comb shape or a zigzag structure. The electrode may be formed on one of the pair of substrates, or may be formed on both substrates. The formation form of the electrodes differs depending on the type of liquid crystal display element. For example, in the case of an IPS type liquid crystal display element (lateral electric field type liquid crystal display element), the electrode is arranged on one of the pair of substrates, and the electrode is placed on the other liquid crystal display element. In the case of a display element, electrodes are arranged on both of the pair of substrates. The liquid crystal alignment film is formed on the substrate or electrode.

In the case of a parallel-aligned liquid crystal display element (for example, IPS, FFS, etc.), the structure includes at least a backlight, a first polarizing film, a first substrate, a first liquid crystal alignment film, a liquid crystal layer, and a second liquid crystal layer from the backlight side. A substrate and a second polarizing film, the polarizing axis of the polarizing film is arranged such that the polarizing axis (direction of polarized light absorption) of the first polarizing film intersects (preferably is orthogonal) with the polarizing axis of the second polarizing film. At this time, the polarization axis of the first polarizing film may be arranged parallel or orthogonal to the alignment direction of the liquid crystal. A liquid crystal display element in which the polarization axis of the first polarizing film is parallel to the alignment direction of the liquid crystal is called an O-mode, and a liquid crystal display element in which the polarization axis of the first polarizing film is arranged in an orthogonal manner is called an E-mode. The liquid crystal alignment film of the present invention can also be applied to either O-mode or E-mode, and can be selected according to the purpose.

Compounds having dichroism can be used in a large number of photoisomerization-type materials. Therefore, when the polarization axis of the polarized light irradiated in order to impart anisotropy to the liquid crystal alignment agent is parallel to and consistent with the polarization axis of the polarized light originating from the polarizing film disposed on the backlight side (in the case of using the liquid crystal alignment agent of the present invention , set to the O-mode configuration), the transmittance of the light absorption wavelength region of the liquid crystal alignment film increases. Therefore, the transmittance of the liquid crystal display element can be further improved.

The liquid crystal layer is formed in such a manner that the liquid crystal composition is sandwiched between the pair of substrates with surfaces on which the liquid crystal alignment film is formed facing each other. In forming the liquid crystal layer, spacers such as microparticles or resin sheets may be used as necessary to interpose between the pair of substrates and form appropriate intervals.

As a method of forming a liquid crystal layer, a vacuum injection method and a liquid crystal drop filling (One Drop Fill, ODF) method are known.

In the vacuum injection method, a gap (cell gap) is set so that the liquid crystal alignment film surfaces face each other, and the injection port of the liquid crystal is left to print the sealant and bond the substrate. Liquid crystal is injected into the cell gap defined by the substrate surface and the sealant using a vacuum differential pressure, and then the injection port is closed to manufacture a liquid crystal display element.

In the ODF method, a sealant is printed on the outer periphery of the liquid crystal alignment film surface of one of a pair of substrates, liquid crystal is dripped in the area inside the sealant, and then the other substrate is bonded with the liquid crystal alignment film surfaces facing each other. Then, the liquid crystal is pressed and spread over the entire surface of the substrate, and then the entire surface of the substrate is irradiated with ultraviolet light to harden the sealant, thereby manufacturing a liquid crystal display element.

Regarding sealants used for bonding substrates, in addition to UV curable sealants, thermosetting sealants are also known. The sealant can be printed by, for example, a screen printing method.

The liquid crystal composition is not particularly limited, and various liquid crystal compositions having positive or negative dielectric anisotropy can be used. Preferable liquid crystal compositions with positive dielectric anisotropy include Japanese Patent No. 3086228, Japanese Patent No. 2635435, Japanese Patent Publication No. 5-501735, and Japanese Patent Publication No. 8-157826. , Japanese Patent Application Laid-Open No. Hei 8-231960, Japanese Patent Application Publication No. Hei 9-241644 (EP885272A1), Japanese Patent Application Publication No. Hei 9-302346 (EP806466A2), Japanese Patent Application Laid-Open No. Hei 8-199168 (EP722998A1), Japanese Patent Laid-Open No. 9-235552, Japanese Patent Laid-Open No. 9-255956, Japanese Patent Laid-Open No. 9-241643 (EP885271A1), Japanese Patent Laid-Open No. 10-204016 (EP844229A1), Japanese Patent Laid-Open No. 10-204016 (EP844229A1), Japanese Patent Laid-Open No. Liquid crystal compositions disclosed in Japanese Patent Application Publication No. 10-204436, Japanese Patent Application Publication No. 10-231482, Japanese Patent Application Publication No. 2000-087040, Japanese Patent Application Publication No. 2001-48822, etc.

Preferable examples of the liquid crystal composition having negative dielectric anisotropy include Japanese Patent Application Laid-Open No. 57-114532, Japanese Patent Application Laid-Open No. 2-4725, and Japanese Patent Application Laid-Open No. 4-224885. Publication No. 10-168076, Japanese Patent Application Publication No. 10-168453, Japanese Patent Application Publication No. 10-236989 No. 10-236990, 10-236992, 10-236993, 10-236994, 10-237000 Publication No. 10-237004, Japanese Patent Application Publication No. 10-237024, Japanese Patent Application Publication No. 10-237035, Japanese Patent Application Publication No. 10-237075, Japanese Patent Application Publication No. 10-237076 Publication No. 10-237448 (EP967261A1), Japanese Patent Application Publication No. 10-287874, Japanese Patent Application Publication No. 10-287875, Japanese Patent Application Publication No. 10-291945, Japanese Patent Application Publication No. 10-291945, Japanese Patent Application Publication No. 10-287874 Publication No. 11-029581, Japanese Patent Application Publication No. 11-080049, Japanese Patent Application Publication No. 2000-256307, Japanese Patent Application Publication No. 2001-019965, Japanese Patent Application Publication No. 2001-072626, Japanese Patent Application Publication No. 2001-072626, Japanese Patent Application Publication No. Publication No. 2001-192657, Japanese Patent Publication No. 2010-037428, International Publication No. 2011/024666, International Publication No. 2010/072370, Japanese Patent Publication No. 2010-537010, Japanese Patent Publication No. 2012-077201 The liquid crystal composition disclosed in the publication, Japanese Patent Application Laid-Open No. 2009-084362, etc.

Even if one or more optically active compounds are added to a liquid crystal composition having positive or negative dielectric anisotropy, there will be no influence.

For example, from the viewpoint of improving alignment, additives may be further added to the liquid crystal composition used in the liquid crystal display element of the present invention. Such additives include photopolymerizable monomers, optically active compounds, antioxidants, ultraviolet absorbers, pigments, defoaming agents, polymerization initiators, polymerization inhibitors, etc. Preferred photopolymerizable monomers, optically active compounds, antioxidants, ultraviolet absorbers, pigments, defoaming agents, polymerization initiators, and polymerization inhibitors include compounds disclosed in International Publication No. 2015/146330 and the like.

In order to be suitable for a liquid crystal display element in a polymer sustained alignment (PSA) mode, a polymerizable compound may be mixed into the liquid crystal composition. Preferred examples of polymerizable compounds include acrylates, methacrylates, vinyl compounds, vinyloxy compounds, allyl ethers, epoxy compounds (oxirane, oxetane), vinyl ketones, etc. Polymerizable based compounds. Preferred compounds include compounds disclosed in International Publication No. 2015/146330 and the like. [Example]

Hereinafter, the present invention will be described based on examples. In addition, the evaluation methods and compounds used in the examples are as follows.

＜Weight average molecular weight (Mw)＞ The weight average molecular weight of polyamide is determined by the GPC method using a 2695 separation module and a 2414 differential refractometer (manufactured by Waters Corporation), and converted to polystyrene. Using a phosphoric acid-dimethylformamide (DMF) mixed solution (phosphoric acid/DMF=0.6/100: weight ratio), the obtained polyamide was treated so that the polyamide concentration became about 2% by weight. Perform dilution. HSPgel RT MB-M (manufactured by Waters) was used as the column, and the mixed solution was used as a developing agent, and the measurement was performed under the conditions of a column temperature of 50°C and a flow rate of 0.40 mL/min. As the standard polystyrene, TSK standard polystyrene manufactured by Tosoh Co., Ltd. was used.

＜Tetracarboxylic dianhydride＞

＜Diamine＞ The compound represented by formula (3-4-1) is a compound in which the two esters on the cyclopropane ring in formula (3-4) are in trans configuration.

＜Solvent＞ NMP: N-methyl-2-pyrrolidone BC: Butyl cellosolve (ethylene glycol monobutyl ether)

<Synthesis of the compound represented by Formula (1A-1)> The compound represented by Formula (1A-1) is obtained as follows. To a solution of 4,4'-methylenediphenylamine (5.30 g, 26.7 mmol) in 2-propanol (100 ml), 1-bromo4-nitrobenzene (10.80 g, 53.5 mmol), 2-bicyclo Hexylphosphino-2',4',6'-triisopropylbiphenyl (0.64 g, 1.34 mmol), tris(dibenzylideneacetone)dipalladium (0.24 g, 0.27 mmol) and potassium carbonate (7.39 g ,53.5 mmol). The solution was stirred with heating at reflux for 90 minutes. After the reaction, cool to room temperature, add water, and extract with ethyl acetate (100 ml × 3 times). The obtained organic layer was washed with saturated brine (100 ml), dried over anhydrous sodium sulfate, and concentrated under reduced pressure. Ethyl acetate was used as the eluent, and the obtained crude body was purified by silica column chromatography to obtain a dinitro compound (yield: 11.5 g, yield 98%).

A solution of dinitro compound (11.5 g, 26.1 mmol) in THF (300 ml) was placed in the autoclave. Pd/C (Pd: 5% by weight, 0.58 g) was added to the solution. After the autoclave was replaced with nitrogen, it was replaced with hydrogen and stirred at room temperature for 14 days. After the reaction was completed, the solid was separated by filtration and concentrated under reduced pressure. The obtained crude body was purified by recrystallization using a mixed solvent (280 ml, toluene/heptane = 6/1 (volume ratio)), thereby obtaining a compound of formula (1A-1) (yield: 6.39 g , yield 64%). ¹ H-NMR (400 MHz, dimethyl sulfoxide (DMSO)-d6); δ 7.33 (s, 2H), δ 6.93 (d, J=6.8 Hz, 4H), δ 6.79 (d, J =6.8 Hz, 4H), δ 6.71 (d, J=7.2 Hz, 4H), δ 6.52 (d, J=6.8 Hz, 4H), δ 4.72 (s, 4H), δ 3.63 (s, 2H).

<Synthesis of the compound represented by formula (1B-2)> The compound represented by formula (1B-2) is obtained by changing 4,4'-methylene diphenylamine as the starting material into m-toluidine, and based on the synthesis method of the compound represented by formula (1A-1). synthesis.

<Synthesis of the compound represented by formula (1C-2)> The compound represented by formula (1C-2) is obtained by changing 4,4'-methylenediphenylamine as the starting material into 4,4'-diaminodiphenylamine, and according to formula (1A-1) The compounds represented are synthesized by the synthetic method.

Preparation of varnish The varnish used in this example was prepared according to the following procedure. Here, the varnishes L1 to L7 prepared in Preparation Examples 1 to 7 are polyamides (corresponding to polymer (L)) obtained by reacting a compound represented by Formula (1) as a raw material. The solution. The varnishes R1 to R2 prepared in Preparation Examples 8 to 9 are polyamide solutions obtained by reacting the compound represented by Formula (1) and the compound having a photoreactive chemical structure without using them as raw materials. , and is a polymer solution for comparison with polymer (L). The varnishes K1 to K2 prepared in Preparation Examples 10 to 11 are polyamides (equivalent to polymer (K)) obtained by reacting at least one compound with a photoreactive chemical structure as a raw material. solution.

[Preparation Example 1] Preparation of Varnish L1 Put 3.384 g of the compound represented by formula (1A-1) and 2.616 g of the compound represented by formula (AN-4-5) into a 100 mL three-necked flask equipped with a stirring wing and a nitrogen introduction tube, and add N-methyl -2-Pyrrolidone (N-methyl-2-pyrrolidone, NMP) 34.0 g and stir. Set to a nitrogen atmosphere, stir at room temperature for 12 hours, add 30.0 g of NMP and 30.0 g of Butyl Cellosolve (BC), and heat and stir the resulting solution at 60°C until the weight of the polymer as solute The varnish L1 was obtained until the average molecular weight became a desired weight average molecular weight, and the weight average molecular weight of the polymer was approximately 77,800 and the solid content concentration was 6% by weight.

[Preparation Example 2 to Preparation Example 11] Preparation of varnishes L2 to varnish L7, varnishes R1 to varnish R2, and varnishes K1 to varnish K2 Varnishes L2 to L7 having a solid content concentration of 6% by weight and varnish R1 for comparison were prepared in the same manner as in Preparation Example 1 except that the compounds used as diamine and tetracarboxylic dianhydride were changed as shown in Table 1. ~Varnish R2. Varnish K1 to varnish K2 were prepared in the same manner as in Preparation Example 1, except that the compounds used as diamine and tetracarboxylic dianhydride were changed as shown in Table 2. The weight average molecular weight of the produced polymer is shown in Table 1 and Table 2. In addition, in Tables 1 and 2, the preparation examples in which two or more compounds are disclosed as diamines mean that all the compounds are combined and used as diamines, and the preparation examples in which two or more compounds are disclosed as tetracarboxylic dianhydride are Preparation examples involving two or more compounds refer to combining all the compounds and using them as tetracarboxylic dianhydride. The numerical values in square brackets indicate the blending ratio (mol %). The empty column means that the compound corresponding to the column is not used.

＜Table 1＞ Varnish Tetracarboxylic dianhydride Diamine Molecular weight (Mw) Preparation Example 1 L1 AN-4-5 [100] 1A-1 [100] 77,800 Preparation Example 2 L2 AN-4-5 [100] 1B-2 [100] 61,500 Preparation Example 3 L3 AN-4-5 [100] 1C-2 [100] 70,500 Preparation Example 4 L4 AN-1-1 [20] AN-2-1 [45] AN-3-2 [35] 1A-1 [30] DI-4-19 [70] 70,400 Preparation Example 5 L5 AN-1-1 [20] AN-2-1 [45] AN-3-2 [35] 1B-2 [30] DI-4-19 [70] 72,600 Preparation Example 6 L6 AN-1-1 [65] AN-3-2 [35] 1A-1 [30] DI-13-1 [50] DI-4-1 [20] 74,500 Preparation Example 7 L7 AN-1-1 [65] AN-3-2 [35] 1B-2 [30] DI-13-1 [50] DI-4-1 [20] 71,000 Preparation Example 8 R1 AN-1-1 [20] AN-2-1 [45] AN-3-2 [35] DI-4-19 [70] DI-13-1 [30] 73,900 Preparation Example 9 R2 AN-1-1 [65] AN-3-2 [35] DI-5-1 m=1 [100] DI-13-1 [50] DI-4-1 [20] 72,000

＜Table 2＞ Varnish Tetracarboxylic dianhydride Diamine Molecular weight (Mw) Preparation Example 10 K1 AN-4-17 m=8 [40] AN-2-1 [30] AN-1-1 [30] 2-1-1 [90] DI-13-1 [7] DI-4-13 [3] 7,200 Preparation Example 11 K2 AN-2-1 [65] AN-3-2 [30] 3-4-1 [100] 45,000

[Example 1] 24.0 g of varnish L1, 16.0 g of varnish K1, and 20.0 g of solvent (NMP/BC=7/3 (weight ratio)) were mixed to prepare an alignment agent 1 with a solid content concentration of 4% by weight. The alignment agent 1 is coated on a glass substrate with an IPS electrode and a glass substrate with a column spacer by the spinner method. After coating, the substrate is heated at 60°C for 80 seconds to evaporate the solvent, and then use Multi-Light ML-501C/B manufactured by Ushio Electric Co., Ltd., vertically relative to the substrate. The direction is separated by a polarizing plate in the polarization wavelength range of 300 nm to 450 nm and a short-wavelength cut-off filter with a cut-on wavelength of 280 nm to irradiate linearly polarized ultraviolet light. The exposure energy at this time was measured using an ultraviolet integrated light meter UIT-150 (light receiver: UVD-S365) manufactured by Ushio Electric Co., Ltd., so that it would be 2.0 ± 0.1 J/cm ² at a wavelength of 365 nm. Adjust exposure time. Thereafter, a calcination process was performed at 230° C. for 30 minutes to form a liquid crystal alignment film with a film thickness of approximately 100 nm.

Then, the two substrates on which the liquid crystal alignment films are formed are bonded together so that the surfaces on which the liquid crystal alignment films are formed face each other, and a gap for injecting the liquid crystal composition is formed between the facing liquid crystal alignment films. At this time, the orientation of the substrate is such that the polarization directions of the linearly polarized light irradiated to each liquid crystal alignment film during the photo-alignment process are parallel to each other. A negative liquid crystal composition A having the following composition was injected into the gap between the bonded substrates to prepare a liquid crystal cell (liquid crystal display element) with a cell thickness of 7 μm.

<Negative liquid crystal composition A> (Physical property values) Phase transition temperature NI: 75.7°C, dielectric anisotropy Δε: -4.1, refractive index anisotropy Δn: 0.101, viscosity η: 14.5 mPa·s.

<Evaluation of voltage holding ratio (VHR) reliability> The voltage retention rate (VHR) of the liquid crystal display element is measured by applying a rectangular wave with a wave height of ±5 V to the unit at 60°C according to the method described in "Mizushima et al., 14th Liquid Crystal Symposium Draft Collection p78 (1988)" . Set the VHR at this time to VHR (before). The voltage retention rate is an indicator of how well the applied voltage is maintained after a frame period. If the value is 100%, it means that all the charge is maintained. The units were exposed to LED backlight for 300 hours and the VHR was measured again. Set the VHR at this time to VHR (after). VHR reliability is evaluated using the VHR reduction rate calculated using the following equation. It can be said that the smaller the VHR reduction rate, the higher the VHR reliability and the higher the stability against light. When the VHR reduction rate is 5% or less, it can be said that the VHR reliability is good. VHR reduction rate (%) = [｜VHR (after) - VHR (before) |/VHR (before)] × 100 The evaluation results are listed in Table 3 together with the evaluation results of Examples 2 to 7 and Comparative Examples 1 to 2.

[Example 2 to Example 5] Alignment agents 2 to 5 were prepared in the same manner as alignment agent 1 except that the varnish shown in Table 3 was used instead of varnish L1. Regarding Alignment Agent 2 to Alignment Agent 5, a liquid crystal cell was produced in the same manner as in Example 1, and the voltage holding ratio was measured and the reliability was evaluated.

[Comparative example 1] Comparative alignment agent 1 was prepared in the same manner as alignment agent 1 except that varnish R1 was used instead of varnish L1. Regarding the comparative alignment agent 1, a liquid crystal cell was produced in the same manner as in Example 1, and the voltage holding ratio was measured and the reliability was evaluated.

[Example 6] 16.0 g of varnish L6, 24.0 g of varnish K2, and 20.0 g of solvent (NMP/BC=7/3 (weight ratio)) were mixed to prepare alignment agent 6 with a solid content concentration of 4% by weight. For Alignment Agent 6, linearly polarized light of ultraviolet rays was irradiated from a polarizing plate with a polarization wavelength range of 230 nm to 310 nm in a vertical direction relative to the substrate. For the exposure energy, an ultraviolet cumulative light meter manufactured by Ushio Electric Co., Ltd. was used. UIT-150 (light receiver: UVD-S254) was used to measure the amount of light, and the linearly polarized light exposure time was adjusted so that it became 0.5 ± 0.1 J/cm ² at a wavelength of 254 nm. The production was carried out in the same manner as in Example 1. Liquid crystal cell, and conduct voltage holding rate measurement and reliability evaluation.

[Example 7, Comparative Example 2] Alignment agent 7 and comparative alignment agent 2 were prepared in the same manner as alignment agent 6 except that the varnish shown in Table 3 was used instead of varnish L6. Regarding the alignment agent 7 and the comparative alignment agent 2, a liquid crystal cell was produced in the same manner as in Example 6, and the voltage holding ratio was measured and the reliability was evaluated.

＜Table 3＞ alignment agent Varnish voltage holding rate before (before) [%] Reduction rate [%] Example 1 Alignment agent 1 L1 K1 95.1 1 Example 2 Alignment agent 2 L2 K1 95.2 1 Example 3 Alignment agent 3 L3 K1 95.5 1 Example 4 Alignment agent 4 L4 K1 95.0 3 Example 5 Alignment agent 5 L5 K1 95.0 3 Example 6 Alignment agent 6 L6 K2 95.0 2 Example 7 Alignment agent 7 L7 K2 95.0 2 Comparative example 1 Compare Alignment Agent 1 R1 K1 94.5 6 Comparative example 2 Compare Alignment Agent 2 R2 K2 93.9 6

As shown in Table 3, the VHR reduction rate in Examples 1 to 3 is 1%, and the blending ratio of the compound represented by formula (1) in polymer L is 30 mol% among all diamines. Also in Examples 4 to 7, the VHR reduction rate was 3% or less and was good. It was found that by using the compound represented by formula (1), a liquid crystal alignment film that maintains a high voltage holding ratio can be produced. [Industrial availability]

If the liquid crystal alignment agent for photo alignment of the present invention is used, a liquid crystal alignment film that maintains a high voltage retention rate even when exposed to strong light can be produced. The liquid crystal alignment agent for optical alignment of the present invention can be suitably used in a lateral electric field type liquid crystal display element.

without

Claims (13)

A liquid crystal alignment agent for photo alignment, comprising a polymer (K) and a polymer (L) which are polymers obtained by reacting a tetracarboxylic acid derivative and a diamine, and in the liquid crystal alignment agent for photo alignment, The raw material composition of the polymer (K) contains a compound having a photoreactive structure and does not contain a compound represented by the formula (1); and, the raw material composition of the polymer (L) contains a compound represented by the formula (1). At least one of the represented compounds and does not include a compound with a photoreactive structure; In formula (1), A ¹ is independently -CH ₃ or -OCH ₃ , a1 is independently an integer from 0 to 2, and X is a divalent compound represented by formula (A), formula (B) or formula (C). base, In the formula (A), * represents a bonding bond and represents the bonding position with the two -NH- in the formula (1), A ² is independently -CH ₃ or -OCH ₃ , and a2 is independently 0~ An integer of 2, n is an integer of 1 to 10, In the formula (B), * represents a bonding bond and represents the bonding position with the two -NH- in the formula (1). A ³ is independently -CH ₃ or -OCH ₃ , and a3 is independently 0~ an integer of 2, In formula (C), * is a bonding bond and represents the bonding position with the two -NH- in formula (1), m is an integer from 0 to 3, formula (1), formula (A) and formula In (B), the group whose bonding position is not fixed on any carbon atom constituting the ring means that it can bond with any carbon atom on the ring that can be bonded. In formula (1), when X is In the case of a divalent group represented by formula (A) or formula (B), the bonding position of -NH ₂ on the benzene ring is independently meta-position or para-position based on the carbon bonded to -NH-. The liquid crystal alignment agent for photo alignment according to claim 1, wherein the compound represented by formula (1) is at least one of the compounds represented by formula (1A-1) to formula (1A-6); . The liquid crystal alignment agent for photo alignment according to claim 1, wherein the compound represented by formula (1) is at least one of the compounds represented by formula (1B-1) to formula (1B-3); . The liquid crystal alignment agent for photo alignment according to claim 1, wherein the compound represented by formula (1) is at least one of the compounds represented by formula (1C-1) and formula (1C-2); . The liquid crystal alignment agent for photo alignment according to claim 1, wherein the photoreaction caused by the photoreactive structure is at least one of photoisomerization, photo Friis rearrangement, photodecomposition and photodimerization. The liquid crystal alignment agent for photo alignment according to any one of claims 1 to 5, wherein the compound with a photoreactive structure contained in the raw material composition of the polymer (K) is formula (2) At least one of the compounds represented; In formula (2 ⁾ _, R ^b is each independently a hydrogen atom, -CH ₃ , -OCH ₃ , -CF ₃ , -F, -COOCH ₃ , or a monovalent group represented by formula (P1-1) or formula (P1-2), R ^c is independently a hydrogen atom, -CH ₃ , -OCH ₃ , -CF ₃ , -F, or a monovalent group represented by formula (P1-1) or formula (P1-2), j is 0 or 1, a～c are independently integers from 0 to 2, In formula (P1-1) and formula (P1-2), R ^6a , R ^7a and R ^8a respectively independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkyl group , a substituted or unsubstituted alkoxycarbonyl group, or a substituted or unsubstituted arylcarbonyl group, * is a bonding bond, and represents the bonding position to the benzene ring in formula (2), formula (2) ), a group whose bonding position is not fixed on any one of the carbon atoms constituting the ring means that it can bond with any one of the bondable carbons on the ring. The liquid crystal alignment agent for photo alignment according to claim 6, wherein the compound represented by formula (2) is at least one of the compounds represented by formula (2-1) to formula (2-3); In the formula (2-1), R ^1a and R ^1c each independently represent a hydrogen atom or a monovalent group represented by the formula (P1-1) or the formula (P1-2). In the formula (2-2), R ^2a and R ^2b each independently represent a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2), and R ^2c each independently represents a hydrogen atom, -CH ₃ , -OCH ₃ , - CF _{3 or -F} , An integer from 0 to 2. In the formula (2-3), R ^3a represents a hydrogen atom or a monovalent group represented by the formula (P1-1) or the formula (P1-2), and R ⁴ and R ⁵ are each independently Hydrogen atom or -F, R ⁴ and R ⁵ are not hydrogen atoms at the same time, R ^3c is independently a hydrogen atom, -CH ₃ , -OCH ₃ , -CF ₃ or -F, and X ₁ is carbon number 1 to 12. Alkylene group, in the alkylene group, more than one non-adjacent -CH ₂ - can be substituted by -O- or -NH-, m is an integer from 0 to 2, In formula (P1-1) and formula (P1-2), R ^6a , R ^7a and R ^8a respectively independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkyl group , substituted or unsubstituted alkoxycarbonyl, or substituted or unsubstituted arylcarbonyl, * is a bond, and represents the same as formula (2-1), formula (2-2) or formula ( 2-3) The bonding position of the benzene ring in formula (2-1), formula (2-2) and formula (2-3), the bonding position is not fixed on any carbon atom constituting the ring The group represents a bond that can be bonded to any of the carbons on the ring that can be bonded. The liquid crystal alignment agent for photo alignment according to claim 1, wherein the compound with a photoreactive structure contained in the raw material composition of the polymer (K) is at least one of the compounds represented by formula (3); In formula (3), R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. R ¹ and R ² may be integrated to form a methylene group, and Independently represents an integer from 0 to 4. The liquid crystal alignment agent for photo alignment according to claim 1 further includes additives. The liquid crystal alignment agent for photo alignment according to claim 9, wherein the additive is at least one selected from the group consisting of oxazoline compounds and epoxy compounds. A liquid crystal alignment film formed from the liquid crystal alignment agent for photo alignment according to any one of claim 1 to claim 10. A liquid crystal element having the liquid crystal alignment film according to claim 11. A method for manufacturing a liquid crystal alignment film, including: the step of coating the liquid crystal alignment agent for photo-alignment as described in any one of claim 1 to claim 10 on a substrate; and the step of irradiating the coating film with polarized ultraviolet rays .