CN117946697A

CN117946697A - Liquid crystal aligning agent, liquid crystal alignment film, liquid crystal element and method for manufacturing liquid crystal alignment film

Info

Publication number: CN117946697A
Application number: CN202311062892.3A
Authority: CN
Inventors: 古川范行
Original assignee: Changsha Dao'anjie New Materials Co ltd
Current assignee: Changsha Dao'anjie New Materials Co ltd
Priority date: 2022-10-18
Filing date: 2023-08-23
Publication date: 2024-04-30
Also published as: TW202417545A; JP2024059149A

Abstract

The invention provides a liquid crystal alignment film capable of forming a liquid crystal display element having excellent contrast and afterimage characteristics and maintaining high voltage holding ratio without degrading display quality even if exposed to strong light for a long time, and a liquid crystal alignment agent, a liquid crystal element and a method for manufacturing the liquid crystal alignment film. A liquid crystal aligning agent comprising at least one polymer and a solvent, wherein the at least one polymer is a polymer obtained by reacting a tetracarboxylic acid derivative with a diamine, and the tetracarboxylic acid derivative comprises at least one selected from the group consisting of a compound represented by the formula (1) and a derivative compound thereof. In the formula (1), R independently represents an alkyl group having 1 to 6 carbon atoms, and n independently represents an integer of 1 to 4.

Description

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

Technical Field

The present invention relates to a liquid crystal aligning agent, a liquid crystal alignment film, and a liquid crystal element using the liquid crystal alignment film. More specifically, the present invention relates to a liquid crystal aligning agent for forming a liquid crystal alignment film of a photo-alignment system (hereinafter, may be abbreviated as a photo-alignment film), a liquid crystal alignment film of a photo-alignment system formed by using the liquid crystal aligning agent, and a liquid crystal display element having the liquid crystal alignment film (hereinafter, may be abbreviated as a liquid crystal element).

Background

There is known a liquid crystal element capable of controlling or modulating an alignment state of a liquid crystal layer in the element to cause an optical phenomenon such as refraction, scattering, reflection, or the like, of electromagnetic waves incident into the element. Specifically, a liquid crystal antenna, a dimming window, an optical compensation material, and a variable phase shifter are known in addition to the following liquid crystal display element.

As liquid crystal display elements, various driving modes such as a twisted nematic (TWISTED NEMATIC, TN) mode, a Super twisted nematic (Super TWISTED NEMATIC, STN) mode, an In-plane switching (In-PLANE SWITCHING, IPS) mode, a fringe field switching (FRINGE FIELD SWITCHING, FFS) mode, and a vertical alignment (VERTICAL ALIGNMENT, VA) mode (Multi-domain vertical alignment (VERTICAL ALIGNMENT)) are known. These liquid crystal display elements are used in image display devices of various electronic devices such as televisions and mobile phones, and have been developed with a view to further improving display quality. Specifically, the improvement in performance of the liquid crystal display element can be achieved not only by the improvement in the driving system and the element structure but also by the structural member used in the element. Among the structural members used in the liquid crystal display device, particularly, a liquid crystal alignment film is one of important materials related to display quality, and in order to meet the demand for higher quality of the liquid crystal display device, the liquid crystal alignment film has been actively studied.

Here, the liquid crystal alignment film is provided on a pair of substrates provided on both sides of the liquid crystal layer of the liquid crystal display element so as to be in contact with the liquid crystal layer, and has a function of aligning liquid crystal molecules constituting the liquid crystal layer with respect to the substrates at a regular pattern. By using a liquid crystal alignment film having high liquid crystal alignment properties, a liquid crystal display element having high contrast and improved afterimage characteristics can be realized (for example, refer to patent documents 1 and 2).

In the formation of such a liquid crystal alignment film, a solution (varnish) obtained by dissolving a polyamic acid, a soluble polyimide or a polyamic acid ester in an organic solvent has been mainly used. When a liquid crystal alignment film is formed 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, and if necessary, an alignment treatment suitable for the display mode is performed. As an orientation treatment method, there is known: a rubbing method in which the surface of the alignment film is rubbed with cloth or the like to adjust the direction of the polymer molecules; since the photo-alignment method, which is a non-contact alignment treatment method in which the alignment film is irradiated with linearly polarized ultraviolet rays to cause photochemical changes such as photoisomerization and dimerization in the polymer molecule, imparts anisotropy to the film, has advantages in that the uniformity of alignment by the photo-alignment method is high compared with the rubbing method, and therefore: the film is not damaged, and the occurrence of display failure of the liquid crystal display element due to dust generation, static electricity and the like can be reduced.

As a liquid crystal alignment film using such a photo-alignment method, for example, patent documents 1 to 6 describe: by using diaminoazobenzene or the like as a raw material and applying a photoisomerization technique, a photoalignment film having a large anchoring energy and good liquid crystal alignment properties is obtained.

[ Prior Art literature ]

[ Patent literature ]

[ Patent document 1] Japanese patent laid-open publication No. 2010-197999

[ Patent document 2] International publication No. 2013/157463

[ Patent document 3] Japanese patent laid-open publication No. 2005-275364

[ Patent document 4] Japanese patent laid-open No. 2007-248637

Patent document 5 japanese patent laid-open publication No. 2009-069493

[ Patent document 6] International publication No. 2015/016118

Disclosure of Invention

[ Problem to be solved by the invention ]

In recent years, high-quality liquid crystal display devices have been increasingly demanded, and contrast, afterimage characteristics, reliability capable of maintaining a high voltage holding ratio (Voltage Holding Ratio, VHR) for a long period, and the like have been demanded. In order to suppress degradation of display quality, it is important to maintain a high voltage holding ratio. On the other hand, in view of outdoor use, it is also required to make the luminance of a backlight serving as a light source higher than before. In the case of exposure to such a high-luminance backlight, it is important to improve VHR reliability for light, and it is a particularly important problem in a photo-alignment film having generally inferior electrical characteristics compared to a rubbing alignment film.

Accordingly, the present inventors have made an effort to provide a liquid crystal alignment film capable of forming a liquid crystal display element having excellent contrast and afterimage characteristics, which can maintain a high voltage holding ratio without deteriorating display quality even when exposed to strong light for a long period of time, and a liquid crystal alignment agent capable of forming such a liquid crystal alignment film.

[ Means of solving the problems ]

As a result of diligent research to solve the above problems, the present inventors have found that a liquid crystal alignment film having high liquid crystal alignment properties can be obtained by using a tetracarboxylic acid derivative represented by formula (1), and that a liquid crystal display element having good contrast and afterimage characteristics can be formed by using the liquid crystal alignment film, and that a high voltage holding ratio can be maintained without lowering display quality even when exposed to strong light for a long period of time, and completed the present invention.

The present invention includes the following structures.

[1] A liquid crystal aligning agent comprising at least one polymer and a solvent, wherein the at least one polymer is a polymer obtained by reacting a tetracarboxylic acid derivative with a diamine, and the tetracarboxylic acid derivative comprises at least one selected from the group consisting of a compound represented by the formula (1) and a derivative compound thereof.

In the formula (1), R independently represents an alkyl group having 1 to 6 carbon atoms, and n independently represents an integer of 1 to 4.

[2] The liquid crystal aligning agent according to [1], wherein the raw material composition used as a raw material of the polymer obtained by reacting a tetracarboxylic acid derivative with a diamine comprises at least one compound selected from the group consisting of a compound represented by the formula (1) and a derivative compound thereof, and a compound having a photoreactive structure which imparts liquid crystal alignment to an alignment film by photoreaction.

[3] The liquid crystal aligning agent according to [2], wherein the photoreaction is at least one of photoisomerization, photo-Fries rearrangement (photo-FRIES REARRANGEMENT), photodecomposition and photodimerization.

[4] The liquid crystal aligning agent according to [2], wherein the compound having a photoreactive structure is at least one of compounds represented by formula (2).

In the formula (2), X is an alkylene group having 1 to 12 carbon atoms, and at least one of the non-adjacent- (CH ₂)₂ -groups) of the alkylene group may be substituted with-O-or-NH-,

R ^a and R ^b are each independently hydrogen, -CH ₃、-OCH₃、-CF₃、-F、-COOCH₃, or a monovalent group represented by the formula (P1-1) or the formula (P1-2),

R ^c is independently hydrogen, -CH ₃、-OCH₃、-CF₃, -F, or a monovalent group represented by the formula (P1-1) or the formula (P1-2), j is 0 or 1, a to c are each independently an integer of 0 to 2,

In the formula (P1-1) and the formula (P1-2), R ^6a、R^7a and R ^8a each independently represent hydrogen, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl 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 or different from each other, represent a bonding position on a benzene ring in the formula (2),

In formula (2), the group whose bonding position is not fixed to any carbon constituting the ring indicates that the bonding position on the ring is arbitrary.

[5] The liquid crystal aligning agent according to [4], wherein the compound represented by the formula (2) is any one of the formulas (2-1) to (2-3).

In the formula (2-1), R ^1a and R ^1c each independently represent hydrogen, 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 hydrogen, or a monovalent group represented by the formula (P1-1) or the formula (P1-2), R ^2c each independently represents hydrogen, -CH ₃、-OCH₃、-CF₃ or-F,

X ₁ is an alkylene group having 1 to 12 carbon atoms, non-adjacent ones of the alkylene groups- (CH ₂)₂) -having a plurality of groups may be substituted by-O-or-NH-, k is an integer of 0 to 2,

In the formula (2-3), R ^3a independently represents hydrogen, or a monovalent group represented by the formula (P1-1) or the formula (P1-2), R ⁴ and R ⁵ independently represent hydrogen or-F, R ⁴ and R ⁵ are not simultaneously hydrogen, R ^3c independently represent hydrogen, -CH ₃、-OCH₃、-CF₃ or-F, X ₁ is an alkylene group having 1 to 12 carbon atoms, one or more non-adjacent ones of- (CH ₂)₂) -of the alkylene groups may be substituted with-O-or-NH-, and m is an integer of 0 to 2,

In the formula (P1-1) and the formula (P1-2), R ^6a、R^7a and R ^8a each independently represent hydrogen, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl 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 or different from each other, represent a bonding position on a benzene ring in the formula (2-1), the formula (2-2) or the formula (2-3),

In the formula (2-1), the formula (2-2) or the formula (2-3), the group whose bonding position is not fixed to any carbon constituting the ring indicates that the bonding position on the ring is arbitrary.

[6] The liquid crystal aligning agent according to [2], wherein the compound having a photoreactive structure is at least one of compounds represented by formula (3).

In the formula (3), R ¹ and R ² each independently represent a water 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 integrally formed to form a methylene group which may be substituted, 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.

[7] The liquid crystal aligning agent according to any one of [1] to [6], wherein the compound represented by the formula (1) is represented by the formula (1-1-1).

[8] A liquid crystal alignment film formed from the liquid crystal alignment agent according to any one of [1] to [7 ].

[9] A liquid crystal element having the liquid crystal alignment film according to [8 ].

[10] A method for manufacturing a liquid crystal alignment film, comprising: a step of applying the liquid crystal aligning agent according to any one of [2] to [7] to a substrate; and irradiating the coating film with polarized ultraviolet rays.

[ Effect of the invention ]

By using the liquid crystal aligning agent of the present invention, a liquid crystal alignment film having high liquid crystal alignment properties can be obtained. Further, by using the liquid crystal alignment film, a liquid crystal display element having excellent afterimage characteristics and contrast, which can maintain a high voltage holding ratio even when exposed to strong light for a long period of time, without deteriorating display quality, can be realized.

Detailed Description

The present invention will be described in detail below. The following description of the structural elements is based on the representative embodiments or specific examples, but the present invention is not limited to such embodiments. As an embodiment of the present invention, the liquid crystal aligning agent of the present invention can be prepared into a liquid crystal aligning agent for photo-alignment by using a compound having a photoreactive structure. The liquid crystal aligning agent for photo-alignment is a liquid crystal aligning agent capable of imparting anisotropy by forming a film thereof on a substrate and irradiating polarized ultraviolet rays, and may be referred to as a "liquid crystal aligning agent" in the present specification. In addition, if an alignment film formed of a liquid crystal alignment agent for photo-alignment is also sometimes referred to as a photo-alignment film, it is also sometimes simply referred to as an alignment film. In the present invention, the term "tetracarboxylic acid derivative" means a tetracarboxylic acid dianhydride, a tetracarboxylic acid diester, or a tetracarboxylic acid diester dihalide. In the present invention, diamine and dihydrazide are sometimes referred to as "diamines".

< Liquid Crystal alignment agent of the invention >

The liquid crystal aligning agent is characterized by comprising at least one polymer selected from the group consisting of polyamic acid and polyamic acid derivatives obtained by reacting tetracarboxylic acid derivatives with diamines, and at least one compound represented by the formula (1) as a raw material of the polymer. In the present invention, the polyamic acid derivative refers to polyimide, partial polyimide, polyamic acid ester, polyamic acid-polyamide copolymer and polyamideimide. The polymer is sometimes referred to as the polymer of the present invention.

Compounds represented by the following formula (1) and derivative compounds thereof

The compound represented by the formula (1) used in the polymer contained in the liquid crystal aligning agent of the present invention will be described.

The derivative compound of the compound represented by the formula (1) is, for example, a tetracarboxylic diester derived from a tetracarboxylic dianhydride or a tetracarboxylic diester dihalide. In the present invention, the "compound represented by the formula (1) and the derivative thereof" may be collectively referred to as "the tetracarboxylic acid derivative represented by the formula (1)".

By using the tetracarboxylic acid derivative represented by the formula (1) as a raw material for a polymer, a liquid crystal display element having excellent contrast and afterimage characteristics can be formed, which can maintain a high voltage holding ratio without deteriorating display quality even when exposed to strong light for a long period of time. The reason is not necessarily clear, but the following is considered.

The tetracarboxylic acid derivative represented by the formula (1) has a biphenyl structure in the central skeleton. By the biphenyl structure, the liquid crystal alignment film using the tetracarboxylic acid derivative represented by the formula (1) as a raw material has strong interaction with liquid crystal molecules, and can exhibit high liquid crystal alignment properties. Thus, it is considered that when a liquid crystal alignment film is formed using a liquid crystal alignment agent containing a polymer using the tetracarboxylic acid derivative represented by formula (1) as a raw material and a liquid crystal display element is formed using the film, excellent afterimage characteristics and contrast are exhibited.

In another aspect, a portion of the hydrogens of the biphenyl structure are substituted with R. By having the R, torsion is generated between the two benzene rings of the biphenyl structure, and pi conjugation of the biphenyl structure is interrupted. Thus, the polyimide alignment film using the tetracarboxylic acid derivative represented by the formula (1) as a raw material can suppress electron conjugation of the polymer chain and reduce the absorption coefficient in the wavelength range of light irradiated from the backlight, as compared with the case of using a normal aromatic tetracarboxylic dianhydride. Therefore, it is considered that VHR reduction of the liquid crystal display element due to light irradiation can be suppressed when a liquid crystal alignment film is formed using a liquid crystal alignment agent containing a polymer using the tetracarboxylic acid derivative represented by formula (1) as a raw material and a liquid crystal display element is formed using the film.

Specific examples of the compound represented by the formula (1) include the following compounds.

In the formulae (1-1) to (1-4), R independently represents an alkyl group having 1 to 6 carbon atoms.

As preferable specific examples of the compounds represented by the formulas (1-1) to (1-4), the formula (1-1-1) can be cited.

The total content of the compounds represented by the formula (1) in the polymer of the present invention is preferably 10 to 50 mol% based on the total amount of the tetracarboxylic acid derivatives in the monomer.

< Compounds having photoreactive Structure >

When the liquid crystal aligning agent of the present invention is used as a liquid crystal aligning agent for photo-alignment, it is preferably used in combination with a compound having a photoreactive structure. In the present specification, the photoreactive structure refers to a structure that causes photoreaction by irradiation with light including a specific wavelength band corresponding to the photoreactive structure. Examples of the photoreaction include: photoisomerization, photofries rearrangement, photodecomposition and photodimerization. The photoreactive structure may be introduced into the polymer by using a compound having the photoreactive structure as a raw material. In the present specification, a compound exemplified as a compound having a photoreactive structure may be used as a raw material when light including a specific wavelength band corresponding to the photoreactive structure is not irradiated during formation of an alignment film from a liquid crystal alignment agent.

When a film of a liquid crystal alignment agent for photoalignment is irradiated with polarized light of a predetermined wavelength during the formation of a liquid crystal alignment film, a liquid crystal alignment film using a compound having a photoreactive structure as described below causes photoreaction to the photoreactive structure of a polymer main chain substantially parallel to the direction of polarized light, and the component of the polymer chain oriented in a specific direction (a direction substantially perpendicular to the direction of polarized light of the irradiated light) is dominant, anisotropy may be imparted to the film. The state in which the component of the polymer chain oriented in a specific direction is dominant is expressed as the polymer chain being oriented. When the photo-alignment film formed by calcining the coating film is used for a liquid crystal display element, the surface of the film subjected to alignment interacts with liquid crystal molecules, and as a result, the liquid crystal molecules align with long axes in a certain direction (a direction substantially perpendicular to the polarization direction of the irradiated light).

Structure for inducing photoisomerization reaction

Examples of the structure causing the photoisomerization reaction in the present invention include a structure having an azobenzene skeleton. In the present specification, the structure having an azobenzene skeleton means a structure represented by the following formula (a).

In the formula (a), each of the bonding bonds is independently arbitrary with respect to the bonding position of the benzene ring, and hydrogen of the benzene ring which can be substituted may be substituted with a substituent.

The compound having an azobenzene structure used in the polymer contained in the liquid crystal aligning agent of the present invention is specifically a compound represented by formula (2).

R ^a and R ^b are each independently hydrogen, -CH ₃、-OCH₃、-CF₃、-F、-COOCH₃, or a monovalent group represented by the formula (P1-1) or the formula (P1-2), R ^c is each independently hydrogen, -CH ₃、-OCH₃、-CF₃, -F, or a monovalent group represented by the formula (P1-1) or the formula (P1-2), j is 0 or 1, a to c are each independently integers of 0 to 2,

The compound represented by the formula (2) is specifically a compound represented by the following formulas (2-1) to (2-3).

In the formula (2-1), R ^1a and R ^1c each independently represent hydrogen, 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 hydrogen, a monovalent group represented by the formula (P1-1) or the formula (P1-2), R ^2c each independently represents hydrogen, -CH ₃、-OCH₃、-CF₃ or-F, X ₁ is an alkylene group having 1 to 12 carbon atoms, one or more non-adjacent ones of the- (CH ₂)₂ -groups may be substituted with-O-or-NH-, and k is an integer of 0 to 2,

In the formula (2-3), R ^3a independently represents hydrogen, a monovalent group represented by the formula (P1-1) or the formula (P1-2), R ⁴ and R ⁵ independently represent hydrogen or-F, R ⁴ and R ⁵ are not simultaneously hydrogen, R ^3c independently represent hydrogen, -CH ₃、-OCH₃、-CF₃ or-F, X ₁ is an alkylene group having 1 to 12 carbon atoms, one or more non-adjacent ones of- (CH ₂)₂) -of the alkylene group may be substituted with-O-or-NH-, and m is an integer of 0 to 2,

In the formula (P1-1) and the formula (P1-2), R ^6a、R^7a and R ^8a each independently represent hydrogen, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl 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 or different from each other, represent bonding positions on benzene rings in the formula (2-1), the formula (2-2) and the formula (2-3),

In the formulae (2-1), (2-2) and (2-3), the group whose bonding position is not fixed to any carbon constituting the ring indicates that the bonding position on the ring is arbitrary.

Specific examples of the compound represented by the formula (2-1) include the following compounds.

In the formula (2-1-2), R ^6a is an alkyl group having 1 to 4 carbon atoms.

Specific examples of the compound represented by the formula (2-2) include the following compounds.

In the formulae (2-2-1) to (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 compounds represented by the formulas (2-3) include the following compounds.

In the formula (2-3-1) and the formula (2-3-2), l is an integer of 1 to 10.

In order to emphasize the transparency of the formed liquid crystal alignment film, it is preferable to use one or more compounds selected from the group consisting of formula (2-1-2), formula (2-1-3), formula (2-2-4), formula (2-2-5) and formula (2-2-6), more preferably formula (2-1-2) or formula (2-1-3), and particularly preferably formula (2-1-2) wherein R ^6a is ethyl.

In the case of focusing attention on obtaining a liquid crystal alignment film (i.e., a liquid crystal alignment agent having high sensitivity) capable of forming an element having good residual image characteristics even when the energy is small during the alignment treatment, it is preferable to use one or more compounds selected from the group consisting of formula (2-1-2), formula (2-1-3), formula (2-2-4), formula (2-2-5), formula (2-2-6), formula (2-3-1) and formula (2-3-2), more preferably formula (2-1-2), formula (2-3-1) or formula (2-3-2), and still more preferably formula (2-1-2) wherein R ^6a is ethyl, and formula (2-3-1) wherein l=2 to 6.

In order to obtain a liquid crystal display element which can maintain a high voltage holding ratio (that is, is excellent in VHR reliability) even when used for a long period of time, it is preferable to use one or more compounds selected from the group consisting of formula (2-1-2), formula (2-1-3), formula (2-2-1), formula (2-2-2), formula (2-2-3), formula (2-2-4), formula (2-2-5) and formula (2-2-6), more preferably a compound represented by l=2 to 6 in formula (2-1-2), formula (2-1-3) or formula (2-2-1), and still more preferably a compound represented by l=2 to 6 in formula (2-1-2) in which R ^6a is ethyl or a compound represented by l=2 to 6 in formula (2-2-1).

In the case where importance is attached to obtaining a liquid crystal display element having a higher contrast ratio, it is preferable to use any one or more compounds selected from the group consisting of the formula (2-1-1), the formula (2-2-1) and the formula (2-2-2), and more preferably the compound represented by the formula (2-1-1) or the formula (2-2-1) where l=2 to 6. In this case, the total content of the compounds selected from the group consisting of the formula (2-1-1), the formula (2-2-1) and the formula (2-2-2) in the polymer is preferably 20 to 100 mol%, more preferably 40 to 100 mol%, based on the total amount of diamine in the monomer.

< Compound having Structure that causes photo-Fries rearrangement reaction >

Examples of the structure that causes the photo-fries rearrangement reaction include a structure having a phenyl ester skeleton. The structure having a phenyl ester skeleton in the present specification refers to a structure represented by the following formula (B).

In the formula (B), the bonding bond is arbitrary relative to the bonding position of the benzene ring, and the hydrogen of the benzene ring which can be substituted by substituent. Preferable examples of the compound having a structure that causes the photo-fries rearrangement reaction used for the polymer contained in the liquid crystal aligning agent of the present invention include the following formula (3). In addition, as the compound having a structure causing the optical Fries rearrangement reaction, compounds represented by the formulae (AN-4-32) to (AN-4-37), formula (DI-5-32), formula (DI-5-33), formula (DI-5-35) and formula (DI-6-8) to (DI-6-10) are exemplified.

In the formula (3), R ¹ and R ² each independently represent hydrogen, halogen, alkyl group having 1 to 6 carbon atoms, haloalkyl group having 1 to 6 carbon atoms, or alkoxy group having 1 to 6 carbon atoms. R ¹ and R ² may be integrated to form a methylene group which may be substituted. X independently represents halogen, alkyl having 1 to 6 carbon atoms, haloalkyl having 1 to 6 carbon atoms or alkoxy having 1 to 6 carbon atoms, and n represents an integer of 0 to 4. M in the formula (DI-5-35) represents an integer of 0 to 12.

Among these, the compound represented by the formula (3) is preferably used in terms of manufacturing a liquid crystal display element having a high contrast, and more preferably a compound in which an amino group on each benzene ring in the formula (3) is located at a para position with respect to an ester group.

The total content of the compounds represented by the formula (3) in the polymer is preferably 40 to 100 mol%, more preferably 70 to 100 mol%, based on the total amount of diamine in the monomer.

Specific examples of the compound represented by the formula (3) include compounds represented by the following formulas (3-1) to (3-6).

Structure for inducing photodecomposition reaction

Examples of the structure that causes the photodecomposition reaction include a structure having a cyclobutane tetracarboxylic acid skeleton. In the present specification, the structure having a cyclobutane tetracarboxylic acid skeleton means a structure represented by the following formula (C).

In formula (C), 1',2and 2' are bond bonds, and either or both of the 1 and 1 'groups and the 2 and 2' groups may bond with the same O. That is, anhydride-CO-O-CO-can be formed. R ^b1、R^b2、R^b3 and R ^b4 are each independently a monovalent organic radical.

Preferred examples of the compound having a structure that causes a photodecomposition reaction to be used in the polymer contained in the liquid crystal aligning agent of the present invention include compounds represented by the following formulas (PA-1) to (PA-6).

In the formulae (PA-3) to (PA-6), R ¹¹ is independently an alkyl group having 1 to 5 carbon atoms.

Structure for inducing photodimerization reaction

Examples of the structure that causes the photodimerization reaction include a structure having a cinnamic acid skeleton. In the present specification, the structure having a cinnamic acid skeleton means a structure represented by the following formula (D).

In the formula (D), the bonding bond is any bonding position relative to the benzene ring, and the hydrogen of the benzene ring which can be substituted by substituent.

As a preferred example of the compound having a structure that causes photodimerization reaction used in the polymer contained in the liquid crystal aligning agent of the present invention, compounds represented by the following formulas (PDI-9) to (PDI-13) are given.

In the formula (PDI-12), R ¹² is an alkyl group or an alkoxy group having 1 to 10 carbon atoms, and at least one hydrogen of the alkyl group or the alkoxy group may be substituted with fluorine.

Among these, a combination with a compound represented by the formula (2) or a compound represented by the formula (3) is preferable.

< Polymer species >)

The polyamic acid and the polyamic acid derivative will be described in detail below.

Here, the polyamic acid is a polymer synthesized by polymerization reaction of tetracarboxylic dianhydride represented by formula (AN) and diamine represented by formula (DI), and has a structural unit represented by formula (PAA). When the liquid crystal alignment agent containing the polyamic acid is heated and calcined in the step of forming the liquid crystal alignment film, the polyamic acid is imidized, and a polyimide liquid crystal alignment film having a structural unit represented by the formula (PI) can be formed.

In the formula (AN), the formula (PAA) and the formula (PI), X ¹ is a tetravalent organic group. In the formula (DI), the formula (PAA) and the formula (PI), X ² is a divalent organic group. For a preferable range and specific examples of the tetravalent organic group in X ¹, reference is made to the structure corresponding to the tetracarboxylic dianhydride described in the present specification. For a preferable range and specific examples of the divalent organic group in X ², reference is made to the description relating to the structure corresponding to the diamine or dihydrazide described in the present specification.

The polyamic acid derivative is a compound having modified properties by substituting a part of the polyamic acid with another atom or group of atoms, and particularly preferably has improved solubility in a solvent used for a liquid crystal aligning agent. Specific examples of such polyamic acid derivatives include: a polyamide-acid-polyamide copolymer obtained by 1) a polyimide obtained by subjecting all amino groups and carboxyl groups of a polyamide acid to a dehydration ring-closure reaction, 2) a partial polyimide obtained by partially subjecting the polyamide acid to a dehydration ring-closure reaction, 3) a polyamide acid ester obtained by converting the carboxyl groups of the polyamide acid into esters, 4) a polyamide acid-polyamide copolymer obtained by substituting a part of the acid dianhydride contained in a tetracarboxylic acid dianhydride compound with an organic dicarboxylic acid and reacting, and 5) a polyamide imide obtained by subjecting a part or all of the polyamide acid-polyamide copolymer to a dehydration ring-closure reaction. Among these derivatives, for example, polyimide having a structural unit represented by the formula (PI) is exemplified, and polyamic acid ester having a structural unit represented by the following formula (PAE) is exemplified.

In formula (PAE), X ¹ is a tetravalent organic radical, X ² is a divalent organic radical, and Y is independently alkyl. For a preferable range and specific example of X ¹、X², reference is made to the description related to X ¹、X² in formula (PAA). Y is preferably a linear or branched alkyl group having 1to 6 carbon atoms, more preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group or a tert-butyl group.

In the case of producing a polyimide as a polyamic acid derivative from a polyamic acid, the obtained polyamic acid solution is subjected to imidization reaction at a temperature of 20 to 150 ℃ together with an acid anhydride such as acetic anhydride, propionic anhydride, trifluoroacetic anhydride or the like as a dehydrating agent, and a tertiary amine such as triethylamine, pyridine, collidine or the like as a dehydrating ring-closure catalyst. Alternatively, polyimide may be obtained by precipitating polyamic acid from the obtained polyamic acid solution using a large amount of a poor solvent (an alcohol-based solvent such as methanol, ethanol, isopropanol, or a glycol-based solvent), and imidizing the precipitated polyamic acid in a solvent such as toluene or xylene together with the dehydrating agent and the dehydration ring-closure catalyst at a temperature of 20 to 150 ℃.

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 amount of the dehydrating agent and the dehydration ring-closure catalyst is preferably 1.5 to 10 times by mol based on the total amount of the molar amount of the tetracarboxylic dianhydride used for the synthesis of the polyamic acid. By adjusting the amount of the dehydrating agent, the catalyst, the reaction temperature and the reaction time used in the imidization reaction, the degree of imidization can be controlled, and thus a part of polyimide obtained by imidizing only a part of polyamic acid can be obtained. The polyimide obtained may be used as a liquid crystal aligning agent by being separated from a solvent used in the reaction and redissolved in another solvent, or may be used as a liquid crystal aligning agent without being separated from the solvent.

The polyamic acid ester can be obtained by the following method: a method of synthesizing the polyamide acid by reacting the polyamide acid with a hydroxyl group-containing compound, a halide, an epoxy group-containing compound, or the like, or a method of synthesizing the polyamide acid by reacting a tetracarboxylic diester derived from a tetracarboxylic dianhydride or a tetracarboxylic diester dichloride with diamines. The tetracarboxylic acid diester derived from the tetracarboxylic acid dianhydride can be obtained, for example, by reacting the tetracarboxylic acid dianhydride with 2 equivalents of an alcohol and ring-opening, and the tetracarboxylic acid diester dichloride can be obtained by reacting the tetracarboxylic acid diester with 2 equivalents of a chlorinating agent (for example, thionyl chloride or the like). The polyamic acid ester may have only an amic acid ester structure, or may be a partially esterified product in which an amic acid structure and an amic acid ester structure coexist.

The polyamic acid or derivative thereof of the present invention can be produced in the same manner as known polyamic acid or derivative thereof used for forming a polyimide film. The total amount of the tetracarboxylic acid derivatives added is preferably 0.9 to 1.1 mol based on 1 mol of the total of the diamines.

The liquid crystal aligning agent of the present invention may contain only one kind of these polyamic acids, polyamic acid esters, and polyimides obtained by imidizing these, or may contain two or more kinds.

The molecular weight of the polyamic acid or derivative thereof of the present invention is preferably 5,000 ～ 500,000, more preferably 5,000 to 50,000 in terms of weight average molecular weight (Mw) in terms of polystyrene. The molecular weight of the polyamic acid or derivative thereof can be determined by measurement by a gel permeation chromatography (Gel Permeation Chromatography, GPC).

The polyamic acid or derivative thereof of the present invention can be confirmed for its presence by the following means: the solid component obtained by precipitating the polyamic acid or derivative thereof of the present invention in a large amount of a poor solvent was analyzed by infrared spectroscopy (infrared spectroscopy, IR) and nuclear magnetic resonance analysis (Nuclear Magnetic Resonance, NMR). In addition, the monomers used can be confirmed by: the polyamic acid or its derivative is decomposed with an aqueous solution of a strong base such as KOH or NaOH by gas chromatography (Gas Chromatography, GC), high performance liquid chromatography (High Performance Liquid Chromatography, HPLC) or gas chromatography mass spectrometry (Gas Chromatography-Mass Spectrometry, GC-MS), and then the extract extracted from the decomposed product is analyzed with an organic solvent.

< Other tetracarboxylic acid derivatives >)

The tetracarboxylic acid derivative other than the compound represented by the formula (1) used as the starting material of 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 can also be derivatized to tetracarboxylic acid diesters or tetracarboxylic acid diester dichlorides for use as starting materials for polymers.

Such tetracarboxylic dianhydrides may be tetracarboxylic dianhydrides belonging to any group of aromatic systems (including heteroaromatic systems) in which dicarboxylic anhydrides are directly bonded to aromatic rings and aliphatic systems (including heterocyclic systems) in which dicarboxylic anhydrides are not directly bonded to aromatic rings.

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

[ Tetracarboxylic dianhydride represented by the formula (AN-1) ]

In the formula (AN-1), G ¹¹ is a single bond, AN alkylene group having 1 to 12 carbon atoms, a1, 4-phenylene group or a1, 4-cyclohexylene group. X ¹¹ is independently a single bond or-CH ₂-.G¹² is independently any of the trivalent radicals described below.

When G ¹² is > CH-, the hydrogen of > CH-may be substituted with methyl. When G ¹² is > N-, G ¹¹ is not a single bond and-CH ₂-,X¹¹ is not a single bond.

R ¹¹ is independently hydrogen or methyl.

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

In the formula (AN-1-2) and the formula (AN-1-14), m is AN integer of 1 to 12 independently.

[ Tetracarboxylic dianhydride represented by the formula (AN-2) ]

In the formula (AN-2), R ⁶¹ is independently hydrogen, alkyl group with 1-5 carbon atoms or phenyl group.

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

[ Tetracarboxylic dianhydride represented by the formula (AN-3) ]

In the formula (AN-3), the ring A ¹¹ is a cyclohexane ring or a benzene ring.

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

[ Tetracarboxylic dianhydride represented by the formula (AN-4) ]

In the formula (AN-4), G ¹³ is a single bond 、-(CH₂)_m-、-O-、-S-、-C(CH₃)₂-、-SO₂-、-CO-、-C(CF₃)₂- or a divalent group represented by the following formula (G13-1), and m is AN integer of 1 to 12. Ring a ¹¹ is each independently a cyclohexane ring or a benzene ring. G ¹³ may be bonded to any position of ring A ¹¹.

In the formula (G13-1), G ^13a and G ^13b are each independently a divalent group represented by a single bond, -O-, -CONH-, or-NHCO-. The phenylene group is preferably a1, 4-phenylene group or a1, 3-phenylene group.

As examples of the tetracarboxylic dianhydride represented by the formula (AN-4), compounds represented by the following formulas (AN-4-1) to (AN-4-31) can be given.

In the formula (AN-4-17), m is AN integer of 1 to 12.

[ Tetracarboxylic dianhydride represented by the formula (AN-5) ]

In formula (AN-5), R ¹¹ is independently hydrogen or methyl. R ¹¹ on the benzene ring in two R ¹¹ is bonded to any one of the positions where substitution can be performed on the benzene ring.

As examples of the tetracarboxylic dianhydride represented by the formula (AN-5), compounds represented by the following formulas (AN-5-1) to (AN-5-3) can be given.

[ Tetracarboxylic dianhydride represented by the formula (AN-6) ]

In formula (AN-6), X ¹¹ is independently a single bond or-CH ₂-.X¹² is-CH ₂-、-CH₂CH₂ -or-ch=ch-. n is 1 or 2. When n is 2, two X ¹² may be the same or different from each other.

As examples of the tetracarboxylic dianhydride represented by the formula (AN-6), compounds represented by the following formulas (AN-6-1) to (AN-6-12) can be given.

[ Tetracarboxylic dianhydride represented by the formula (AN-7) ]

In the formula (AN-7), X ¹¹ is a single bond or-CH ₂ -.

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

[ Tetracarboxylic dianhydride represented by the formula (AN-8) ]

In the formula (AN-8), X ¹¹ is a single bond or-CH ₂-.R¹² is hydrogen, methyl, ethyl or phenyl. Ring a ¹² is a cyclohexane ring or cyclohexene ring.

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

[ Tetracarboxylic dianhydride represented by the formula (AN-9) ]

In the formula (AN-9), r is 0 or 1 independently.

As examples of the tetracarboxylic dianhydride represented by the formula (AN-9), compounds represented by the following formulas (AN-9-1) to (AN-9-3) can be given.

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

[ Tetracarboxylic dianhydride represented by the formula (AN-11) ]

In the formula (AN-11), the ring A ¹¹ is independently a cyclohexane ring or a benzene ring.

As examples of the tetracarboxylic dianhydride represented by the formula (AN-11), compounds represented by the following formulas (AN-11-1) to (AN-11-3) can be given.

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[ Tetracarboxylic dianhydride represented by the formula (AN-12) ]

In the formula (AN-12), the rings A ¹¹ are each independently a cyclohexane ring or a benzene ring.

As examples of the tetracarboxylic dianhydride represented by the formula (AN-12), compounds represented by the following formulas (AN-12-1) to (AN-12-3) can be given.

[ Tetracarboxylic dianhydride represented by the formula (AN-15) ]

In the formula (AN-15), w is AN integer of 1 to 10.

As examples of the tetracarboxylic dianhydride represented by the formula (AN-15), compounds represented by the following formulas (AN-15-1) to (AN-15-3) can be given.

[ Tetracarboxylic dianhydrides represented by the formulae (AN-16-1) to (AN-16-15) ]

As the tetracarboxylic dianhydride other than the above, compounds represented by the following formulas (AN-16-1) to (AN-16-15) are mentioned.

Suitable materials for improving the respective characteristics of the liquid crystal alignment film described later among the tetracarboxylic dianhydrides will be described. In the case where importance is attached to further improvement of the liquid crystal alignment, the compound represented by the formula (AN-1-2), the formula (AN-4-17), the formula (AN-4-21) or the formula (AN-4-29) is more preferable, m=4 to 8 in the formula (AN-1-2), and m=4 to 8 in the formula (AN-4-17).

In the case where importance is attached to improving the transmittance of the liquid crystal display element, the compound represented by the formula (AN-1-1), the formula (AN-1-2), the formula (AN-2-1), the formula (AN-3-1), the formula (AN-4-17), the formula (AN-4-30), the formula (AN-5-1), the formula (AN-7-2), the formula (AN-10-1), the formula (AN-16-3) or the formula (AN-16-4) is preferable, wherein m=4 or 8 is preferable in the formula (AN-1-2), and m=4 to 8 is preferable in the formula (AN-4-17), and m=8 is more preferable.

In the case where enhancement of VHR of a liquid crystal display element is important, the compound represented by the formula (AN-1-1), the formula (AN-1-2), the formula (AN-3-1), the formula (AN-4-17), the formula (AN-4-30), the formula (AN-7-2), the formula (AN-10-1), the formula (AN-16-3), the formula (AN-16-4) or the formula (AN-2-1) is preferable, m=4 or 8 is preferable in the formula (AN-1-2), and m=4 or 8 is preferable in the formula (AN-4-17), and m=8 is more preferable in the formula (AN-4-17).

As one of the methods for preventing the burn-in, it is effective to reduce the volume resistance value of the liquid crystal alignment film to increase the relaxation rate of the residual charge (Direct Current (DC)) in the liquid crystal alignment film. In the case where the above object is emphasized, the compound represented by the formula (AN-1-13), the formula (AN-3-2), the formula (AN-4-21), the formula (AN-4-29) or the formula (AN-11-3) is preferable.

< Other diamines >)

Diamines other than the compounds represented by the formula (2) or the formula (3) used as the raw material of the polymer of the present invention can be selected from known diamines without limitation.

Diamines can be divided into two types according to their structure. That is, a diamine having a side chain group, which is a group branching from the main chain when the skeleton linking two amino groups is regarded as the main chain, and a diamine having no side chain group. In the following description, such a diamine having a side chain group may be referred to as a side chain diamine. Such a diamine having no side chain group is sometimes referred to as a non-side chain diamine. The side chain group is a group having an effect of increasing the pretilt angle.

By appropriately separating the non-side chain type diamine from the side chain type diamine, it is possible to correspond to the respective desired pretilt angles.

The side chain type diamine is preferably used in combination to such an extent that the characteristics of the present invention are not impaired. The side chain type diamine and the non-side chain type diamine are preferably used by selecting them for the purpose of improving the vertical alignment property with respect to liquid crystal, VHR, and the characteristics such as the afterimage characteristic.

The known diamines having no side chain are shown in the following formulas (DI-1) to (DI-16).

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 m-CH ₂ -) can be substituted by-NH-or-O-, at least one hydrogen of m-CH ₂ -may be substituted with hydroxy or methyl. m is an integer of 1 to 12. When m in DI-1 is 2 or more, a plurality of G ²⁰ may be the same or different from each other. Wherein, when G ²⁰ is the formula (DI-1-a), m is 1.

In the formula (DI-1-a), v is an integer of 1 to 6 independently of each other.

In the formula (DI-3), the formula (DI-6) and the formula (DI-7), G ²¹ is independently a single bond 、-NH-、-NCH₃-、-O-、-S-、-S-S-、-SO₂-、-CO-、-COO-、-CONCH₃-、-CONH-、-C(CH₃)₂-、-C(CF₃)₂-、-(CH₂)_m-、-O-(CH₂)_m-O-、-N(CH₃)-(CH₂)_k-N(CH₃)-、-(O-C₂H₄)_m-O-、-O-CH₂-C(CF₃)₂-CH₂-O-、-O-CO-(CH₂)_m-CO-O-、-CO-O-(CH₂)_m-O-CO-、-(CH₂)_m-NH-(CH₂)_m-、-CO-(CH₂)_k-NH-(CH₂)_k-、-(NH-(CH₂)_m)_k-NH-、-CO-C₃H₆-(NH-C₃H₆)_n-CO- or-S- (CH ₂)_m -S-, m is independently an integer of 1 to 12, k is an integer of 1 to 5, and n is 1 or 2.

In the formula (DI-4), s is independently an integer of 0 to 2.

In the formula (DI-5), G ³³ is a single bond 、-NH-、-NCH₃-、-O-、-S-、-S-S-、-SO₂-、-CO-、-COO-、-CONCH₃-、-CONH-、-C(CH₃)₂-、-C(CF₃)₂-、-(CH₂)_m-、-O-(CH₂)_m-O-、-N(CH₃)-(CH₂)_k-N(CH₃)-、-(O-C₂H₄)_m-O-、-O-CH₂-C(CF₃)₂-CH₂-O-、-O-CO-(CH₂)_m-CO-O-、-CO-O-(CH₂)_m-O-CO-、-(CH₂)_m-NH-(CH₂)_m-、-CO-(CH₂)_k-NH-(CH₂)_k-、-(NH-(CH₂)_m)_k-NH-、-CO-C₃H₆-(NH-C₃H₆)_n-CO- or -S-(CH₂)_m-S-、-N(Boc)-(CH₂)_e-N(Boc)-、-NH-(CH₂)_e-N(Boc)-、-N(Boc)-(CH₂)_e-、-(CH₂)_m-N(Boc)-CONH-(CH₂)_m-、-(CH₂)_m-N(Boc)-(CH₂)_m-、 or a group represented by the following formula (DI-5-a) or the following formula (DI-5-b), m is independently an integer of 1 to 12, k is an integer of 1 to 5, e is an integer of 2 to 10, and n is 1 or 2.Boc is tert-butoxycarbonyl.

In the formula (DI-6) and the formula (DI-7), G ²² is independently a single bond, -O-, -S-, -CO-, -C (CH ₃)₂-、-C(CF₃)₂ -or alkylene of 1-10 carbon atoms).

At least one hydrogen of the cyclohexane ring and the benzene ring in the formulae (DI-2) to (DI-7) may be substituted with-F, -Cl, an alkylene group having 1 to 3 carbon atoms, -OCH ₃、-OH、-CF₃、-CO₂H、-CONH₂、-NHC₆H₅, a phenyl group or a benzyl group, and in addition, in the formula (DI-4), at least one hydrogen of the cyclohexane ring and the benzene ring may be substituted with one selected from the group of groups represented by any one of the following formulae (DI-4-a) to (DI-4-i), and in the formula (DI-5), when G ³³ is a single bond, at least one hydrogen of the cyclohexane ring and the benzene ring may be substituted with NHBoc or N (Boc) ₂.

The group whose bonding position is not fixed to the carbon constituting the ring indicates that the bonding position on the ring is arbitrary. Further, the bonding position of-NH ₂ to the cyclohexane ring or the benzene ring is any position other than the bonding position of G ²¹、G²² or G ³³.

In the formula (DI-4-a) and the formula (DI-4-b), R ²⁰ is independently hydrogen or-CH ₃. In the formula (DI-4-f) and the formula (DI-4-g), m is an integer of 0 to 12, and Boc is tert-butoxycarbonyl.

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

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

In the formula (DI-12), R ²¹ and R ²² are each independently an alkyl group having 1 to 3 carbon atoms or a phenyl group, G ²³ is independently an alkylene group having 1 to 6 carbon atoms, a phenylene group or an alkyl-substituted phenylene group, and w is an integer of 1 to 10.

In the 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 an integer of 0 to 4.

In the formula (DI-14), the ring B is a monocyclic heterocyclic aromatic group, R ²⁴ is hydrogen, -F, -Cl, alkyl, alkoxy, alkenyl or alkynyl of 1-6 carbon atoms, and q is independently an integer of 0-4. When q is 2 or more, a plurality of R ²⁴ may be the same or different from each other.

In the formula (DI-15), the 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. The group whose bonding position is not fixed to the carbon constituting the ring indicates that the bonding position on the ring is arbitrary. In the formulae (DI-13) to (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 formulas (DI-1-1) to (DI-1-9).

In the formula (DI-1-7) and the formula (DI-1-8), k is an integer of 1 to 3, respectively. In the formula (DI-1-9), v is an integer of 1 to 6 independently of each other.

Examples of the diamines represented by the following formulas (DI-2) to (DI-3) are shown in the following formulas (DI-2-1), (DI-2-2) and (DI-3-3) of the formulas (DI-3-3).

Examples of the diamine represented by the formula (DI-4) are shown in the following formulas (DI-4-1) to (DI-4-27).

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In the formula (DI-4-20) and the formula (DI-4-21), m is an integer of 1 to 12, respectively.

Examples of the diamine represented by the formula (DI-5) are shown in the following formulas (DI-5-1) to (DI-5-50).

In the formula (DI-5-1), m is an integer of 1 to 12.

In the formula (DI-5-12) and the formula (DI-5-13), m is an integer of 1 to 12, respectively.

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

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

In the formulae (DI-5-35) to (DI-5-37) and (DI-5-39), m is an integer of 1 to 12, in the formulae (DI-5-38) and (DI-5-39), k is an integer of 1 to 5, and in the formulae (DI-5-40), n is 1 or 2.

In the formulae (DI-5-42) to (DI-5-44), e is an integer of 2 to 10, and in the formula (DI-5-45), R ⁴³ is hydrogen, -NHBoc or-N (Boc) ₂. In the formulae (DI-5-42) to (DI-5-44), boc is t-butoxycarbonyl.

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

Examples of the diamine represented by the formula (DI-7) are shown in the following formulas (DI-7-1) to (DI-7-11).

In the formula (DI-7-3) and the formula (DI-7-4), m is an integer of 1 to 12, and n is 1 or 2.

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

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

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

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

An example of the diamine represented by the formula (DI-12) is shown in the following formula (DI-12-1).

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

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

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

An example of the diamine represented by the formula (DI-16) is shown in the following formula (DI-16-1).

Next, dihydrazide used in the raw material of the polymer of the present invention will be described. As the known dihydrazide having no side chain, compounds represented by any one of the following formulas (DIH-1) to (DIH-3) can be mentioned.

In the formula (DIH-1), G ²⁵ is a single bond, alkylene of 1 to 20 carbon atoms, -CO- -O-, -S-, -SO ₂-、-C(CH₃)₂ -, or-C (CF ₃)₂ -.

In the formula (DIH-2), ring D is a cyclohexane ring, a benzene ring or a naphthalene ring, and at least one hydrogen of the group may be substituted with a methyl group, an ethyl group or a phenyl group.

In the formula (DIH-3), the rings E are each independently a cyclohexane ring or a benzene ring, and at least one hydrogen of the groups may be substituted with a methyl group, an ethyl group or a phenyl group. The plurality of rings E may be the same as or different from each other. Y is a single bond, an alkylene group having 1 to 20 carbon atoms, -CO-, -O-, -S-, -SO ₂-、-C(CH₃)₂ -or-C (CF ₃)₂ -.

In the formulae (DIH-2) and (DIH-3), the bonding position of-CONHNH ₂ bonded to the ring is an arbitrary position.

Examples of the compounds represented by any of the formulae (DIH-1) to (DIH-3) are shown in the following formulae (DIH-1-1), formula (DIH-1-2), formulae (DIH-2-1) to (DIH-2-3), and formulae (DIH-3-1) to (DIH-3-6).

In the formula (DIH-1-2), m is an integer of 1 to 12.

Diamines suitable for the purpose of increasing the pretilt angle are described. The compound of the present invention can be suitably used in a liquid crystal aligning agent used for a transverse electric field type liquid crystal display element, but can also be used in combination with a diamine as described below to increase a pretilt angle. As the diamine having a side chain group suitable for the purpose of increasing the pretilt angle, diamines represented by any one of the formulas (DI-31) to (DI-35) and the formulas (DI-36-1) to (DI-36-8) may be mentioned.

In the formula (DI-31), G ²⁶ is a single bond, -O-, -COO-, -OCO-, -CO-, -CONH-, -CH ₂O-、-OCH₂-、-CF₂O-、-OCF₂ -or- (CH ₂)_ma -, preferred examples of G ²⁶ are single bond, -O-, -COO-, -OCO-, -CH ₂ O-, or alkylene of 1 to 3 carbon atoms, particularly preferred examples are a single bond, -O-, -COO-, -OCO-, -CH ₂O-、-CH₂ -or-CH ₂CH₂-.R²⁵ 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), at least one hydrogen may be substituted by-F, and at least one of-CH ₂ -may be substituted by-O-, -CH=CH-or-C.ident.C-the hydrogen of the phenyl group may be substituted by-F, -CH ₃、-OCH₃、-OCH₂F、-OCHF₂、-OCF₃, an alkyl group having 3 to 30 carbon atoms or an alkoxy group having 3 to 30 carbon atoms the bonding position of-NH ₂ bonded to the benzene ring means that it is at any position on the ring, in the case where the bonding position of the base "R ²⁵-G²⁶ -" is set to 1 position, the bonding positions are preferably 3 to 5 or 2 to 5.

In the formula (DI-31-a), G ²⁷、G²⁸ and G ²⁹ are a bond group, each independently is a single bond or an alkylene group having 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 each independently a1, 4-phenylene group, a1, 4-cyclohexylene group, a1, 3-dioxane (dioxane) -2, 5-diyl group, a pyrimidine-2, 5-diyl group, a pyridine-2, 5-diyl group, a naphthalene-1, 5-diyl group, a naphthalene-2, 7-diyl group or an anthracene-9, 10-diyl group, at least one hydrogen in ring B ²¹, ring B ²², ring B ²³ and ring B ²⁴ is replaced by-F or-CH ₃, s, t and u are each independently integers of 0 to 2, the total of them is 1 to 5, and when s, t or u is 2, two bonding groups in each bracket may be the same or different, and two rings may be the same or different. R ²⁶ is hydrogen, -F, -OH, alkyl of 1 to 30 carbon atoms, fluoro-substituted alkyl of 1 to 30 carbon atoms, alkoxy of 1 to 30 carbon atoms, -CN, -OCH ₂F、-OCHF₂ or-OCF ₃, at least one of the alkyl of 1 to 30 carbon atoms-CH ₂ -being substituted by a divalent group represented by the following formula (DI-31-b).

In the 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. A preferred example of R ²⁶ is an alkyl group having 1 to 30 carbon atoms or an alkoxy group having 1 to 30 carbon atoms.

In the formula (DI-32) and the formula (DI-33), G ³⁰ is independently a single bond, -CO-, or-CH ₂-,R²⁹ is independently hydrogen or-CH ₃,R³⁰ is hydrogen, alkyl of 1 to 20 carbon atoms, or alkenyl of 2 to 20 carbon atoms. At least one hydrogen of the benzene ring in the formula (DI-33) may be substituted with an alkyl group having 1 to 20 carbon atoms or a phenyl group. The base group whose bonding position is not fixed to any carbon constituting the ring indicates that the bonding position on the ring is arbitrary. Preferably two groups of formula (DI-32) -phenylene-G ³⁰ -O- "are bonded one to the 3-position of the steroid nucleus and the other to the 6-position of the steroid nucleus. The bonding position of the two groups "-phenylene-G ³⁰ -O-" in the formula (DI-33) on the benzene ring is preferably meta-or para-relative to the bonding position of the steroid nucleus, respectively. In the formula (DI-32) and the formula (DI-33), the-NH ₂ bonded to the benzene ring represents that the bonding position on the ring is arbitrary.

In the formula (DI-34) and the 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 hydrogen or alkyl with 1-20 carbon atoms, at least one of the alkyl groups-CH ₂ -may be substituted by-O-, -ch=ch-, or-c≡c-. R ³² is C6-22 alkyl, R ³³ is hydrogen or C1-22 alkyl. Ring B ²⁵ is 1, 4-phenylene or 1, 4-cyclohexylene, r being 0 or 1. Further, -NH ₂ bonded to the benzene ring means that the bonding position on the ring is arbitrary, and is preferably independently meta or para to the bonding position of G ³¹.

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

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

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

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In the formulae (DI-31-18) to (DI-31-43), R ³⁸ is independently 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 or an alkoxy group having 3 to 20 carbon atoms. R ³⁹ is independently hydrogen, -F, alkyl of 1 to 30 carbon atoms, alkoxy of 1 to 30 carbon atoms, -CN, -OCH ₂F、-OCHF₂ or-OCF ₃, preferably alkyl of 3 to 25 carbon atoms or alkoxy of 3 to 25 carbon atoms. Further, G ³³ is an alkylene group having 1 to 20 carbon atoms.

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

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

Examples of the compounds represented by the formula (DI-34) are shown in the following formulas (DI-34-1) to (DI-34-12).

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In the formulae (DI-34-1) to (DI-34-12), R ⁴⁰ is independently hydrogen or an alkyl group having 1 to 20 carbon atoms, preferably hydrogen or an alkyl group having 1 to 10 carbon atoms, and R ⁴¹ is independently hydrogen or an alkyl group having 1 to 12 carbon atoms.

Examples of the compounds represented by the formula (DI-35) are shown in the following formulas (DI-35-1) to (DI-35-3).

In the formulae (DI-35-1) to (DI-35-3), R ³⁷ is independently an alkyl group having 6 to 30 carbon atoms, and R ⁴¹ is independently hydrogen or an alkyl group having 1 to 12 carbon atoms.

The compounds represented by the following formulas (DI-36-1) to (DI-36-8) are shown below.

In the formulae (DI-36-1) to (DI-36-8), R ⁴² is independently an alkyl group having 3 to 30 carbon atoms.

Suitable materials for improving the respective characteristics of the liquid crystal alignment film described later among the diamines will be described. In the case where improvement of the liquid crystal alignment property is important, the compound represented by the formula (DI-1-3), the formula (DI-5-1), the formula (DI-5-5), the formula (DI-5-9), the formula (DI-5-12), the formula (DI-5-13), the formula (DI-5-29), the formula (DI-6-7), the formula (DI-7-3) or the formula (DI-11-2) is preferably used. In the formula (DI-5-1), m=2 to 8 is preferable, and m=4 to 8 is more preferable. In the formula (DI-5-12), m=2 to 6 is preferable, and m=5 is more preferable. In the formula (DI-5-13), m=1 or 2 is preferable, and m=1 is more preferable.

In the case where enhancement of transmittance is important, it is preferable to use a diamine represented by the formula (DI-1-3), the formula (DI-2-1), the formula (DI-5-5), the formula (DI-5-24) or the formula (DI-7-3), and more preferable is a compound represented by the formula (DI-2-1). In the formula (DI-5-1), m=2 to 8 is preferable, and m=8 is more preferable. In the formula (DI-7-3), m=2 or 3 and n=1 or 2 are preferable, and m=3 and n=1 are more preferable.

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

As one of the methods for preventing burn-in, it is effective to reduce the volume resistance value of the liquid crystal alignment film to increase the relaxation rate of the residual charge (residual DC) in the liquid crystal alignment film. In the case where the above object is emphasized, the compound represented by the formula (DI-4-1), the formula (DI-4-2), the formula (DI-4-10), the formula (DI-4-15), the formula (DI-5-1), the formula (DI-5-12), the formula (DI-5-13), the formula (DI-5-28), the formula (DI-4-20), the formula (DI-4-21), the formula (DI-7-12) or the formula (DI-16-1) is preferably used, and the compound represented by the formula (DI-4-1), the formula (DI-5-1) or the formula (DI-5-13) is more preferably used. In the formula (DI-5-1), m=2 to 8 is preferable, and m=4 to 8 is more preferable. In the formula (DI-5-12), m=2 to 6 is preferable, and m=5 is more preferable. In the formula (DI-5-13), m=1 or 2 is preferable, and m=1 is more preferable. In the formula (DI-7-12), m=3 or 4 is preferable, and m=4 is more preferable.

In the raw material composition used as a raw material for the polymer of the present invention, a part of the diamines may be substituted with at least one selected from the group consisting of monoamines and monoazides. The ratio of substitution is preferably in the range of 40 mol% or less of at least one member selected from the group consisting of monoamines and monoazides to diamines. Such substitution can cause termination of the polymerization reaction when the polyamic acid is formed, and further progress of the polymerization reaction can be suppressed. Therefore, by such substitution, the molecular weight of the obtained polymer (polyamic acid or derivative thereof) can be easily controlled, and for example, the coating property of the liquid crystal aligning agent can be improved without impairing the effect of the present invention. The diamine which may be substituted with monoamine or monoazide may be one kind or two or more kinds as long as the effects of the present invention are not impaired. Examples of the monoamine include: aniline, 4-hydroxyaniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-undecylamine, n-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, n-eicosylamine, p-aminophenyltrimethoxysilane and 3-aminopropyltriethoxysilane.

In the case where the polymer of the present invention is a polyamic acid or derivative thereof, the raw material composition thereof may further contain a monoisocyanate compound as a monomer. By containing a monoisocyanate compound as a monomer, the terminal of the obtained polyamic acid or derivative thereof is modified, and the molecular weight is regulated. By using the terminal-modified polyamic acid or derivative thereof, for example, the coating properties of the liquid crystal aligning agent can be improved without impairing the effects of the present invention. From the viewpoint of the above, 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.

The liquid crystal aligning agent of the present invention may contain one kind of the polymer of the present invention, or the polymer of the present invention and a polymer other than the polymer of the present invention may be mixed. In this specification, a liquid crystal aligning agent containing one of the polymers is sometimes referred to as a single layer liquid crystal aligning agent. A liquid crystal aligning agent in which two or more kinds of the polymers are mixed is sometimes referred to as a blended liquid crystal aligning agent. The blended liquid crystal aligning agent is particularly used in the case of paying attention to VHR reliability and other electrical characteristics.

The polymer other than the polymer of the present invention used in the blended liquid crystal aligning agent is preferably at least one of polyamic acid and polyamic acid derivatives. The polyamide acid and the polyamide acid derivative as the polymer other than the polymer of the present invention may be described with reference to the polymer of the present invention except that the compound represented by the formula (1) as the raw material composition is not included.

In the case of using a two-component polymer, there are, for example, the following modes: one of them selects a polymer having excellent properties in terms of liquid crystal aligning ability, and the other selects a polymer having excellent properties for improving the electrical characteristics of a liquid crystal display element, and is suitable for obtaining an aligning agent having a good balance of liquid crystal aligning properties and electrical characteristics.

In this case, by controlling the structure and molecular weight of each polymer, in the process of forming a thin film by applying a liquid crystal aligning agent obtained by dissolving these polymers in a solvent onto a substrate and predrying the same as described later, a polymer having excellent properties in terms of liquid crystal aligning ability is segregated (segregation) in an upper layer of the thin film, and a polymer having excellent properties in terms of improving electrical properties of a liquid crystal display element is segregated in a lower layer of the thin film. Among the polymers mixed, a phenomenon in which a polymer having low surface energy is separated from an upper layer and a polymer having high surface energy is separated from a lower layer may be used. The confirmation of such layer separation can be confirmed by: the surface energy of the formed liquid crystal alignment film is the same as or similar to the surface energy of a film formed of a liquid crystal alignment agent containing only a polymer intended to segregate in the upper layer.

In the liquid crystal aligning agent containing a mixture of polymers, layer separation can be also exhibited by forming a polyimide from a polymer to be segregated in an upper layer.

The compound represented by the formula (1) can be used as a raw material for a polymer segregated in an upper layer of the film, a raw material for a polymer segregated in a lower layer of the film, and a raw material for two polymers, more preferably a raw material for a polymer segregated in an upper layer of the film.

The compound having a photoreactive structure may be used as a raw material of a polymer segregated in an upper layer of the film, a raw material of a polymer segregated in a lower layer of the film, or a raw material of two polymers, more preferably, a raw material of a polymer segregated in an upper layer of the film.

The tetracarboxylic dianhydride other than the compound represented by the formula (1) segregated in the upper layer of the film and the polyamic acid or derivative segregated in the lower layer of the film can be selected from the exemplified known tetracarboxylic dianhydrides without limitation.

The tetracarboxylic dianhydride used for synthesizing the polyamic acid or derivative thereof segregated in the upper layer of the film is preferably a compound represented by the formula (AN-1-1), the formula (AN-1-2), the formula (AN-2-1), the formula (AN-3-1), the formula (AN-4-5) or the formula (AN-4-17), more preferably the formula (AN-2-1) or the formula (AN-4-17). In the formula (AN-4-17), m=4 to 8 is preferable.

The tetracarboxylic dianhydride of the polyamic acid or derivative thereof, which is segregated in the lower layer of the film, is preferably a compound represented by the formula (AN-1-1), the formula (AN-1-13), the formula (AN-2-1), the formula (AN-3-2) or the formula (AN-4-21), more preferably the formula (AN-1-1), the formula (AN-2-1) or the formula (AN-3-2).

The tetracarboxylic dianhydride used for synthesizing the polyamic acid or derivative thereof segregated in the lower layer of the film preferably contains 10 mol% or more of aromatic tetracarboxylic dianhydride, more preferably 30 mol% or more of the total amount of tetracarboxylic dianhydride.

The diamine used for synthesizing the polyamic acid or derivative thereof segregated in the upper layer of the film and the polyamic acid or derivative thereof segregated in the lower layer of the film may be selected from the known diamines exemplified above without limitation.

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

As the diamine for synthesizing the polyamic acid or derivative thereof segregated in the lower layer of the film, preferred are compounds represented by the formula (DI-4-1), the formula (DI-4-2), the formula (DI-4-10), the formula (DI-4-18), the formula (DI-4-19), the formula (DI-5-1), the formula (DI-5-9), the formula (DI-5-28), the formula (DI-5-30), the formula (DI-13-1) or the formula (DIH-1-2). The compound of formula (DI-5-1) is preferably m=1 or 2, and the compound of formula (DI-5-30) is preferably k=2. Among them, the compounds represented by the formula (DI-4-1), the formula (DI-4-18), the formula (DI-4-19), the formula (DI-5-9), the formula (DI-13-1) or the formula (DIH-1-2) are more preferable.

The diamine used for synthesizing the polyamic acid or derivative thereof segregated in the lower layer of the film preferably contains 30 mol% or more of at least one selected from the group consisting of aromatic diamine and aromatic dihydrazide, more preferably 50 mol% or more, with respect to all diamines.

The proportion of the polyamic acid or derivative thereof segregated in the upper layer of the film to the total amount of the polyamic acid or derivative thereof segregated in the upper layer of the film and the polyamic acid or derivative thereof segregated in the lower layer of the film is preferably 5 to 60% by weight, more preferably 20 to 50% by weight.

The polyamic acid or derivative thereof of the present invention may be a block polymer comprising a first polymer chain and a second polymer chain having a different structure from the first polymer chain. In addition, the block polymer may further comprise other polymer chains having a structure different from that of the first polymer chain and the second polymer chain. For example, the block polymer of polyamic acid can be formed by mixing and heating a solution of a specific polyamic acid (PAA 1) represented by the formula (PAA) with a solution of a polyamic acid (PAA 2) different from the polyamic acid (PAA 1) and a combination of X ¹ and X ². The block polymer of the polyamic acid thus formed comprises a block represented by (PAA 1) _n1 and a block represented by (PAA 2) _n2. N1 and n2 in (PAA 1) _n1 and (PAA 2) _n2 are each independently an integer of 1 or more, preferably each independently an integer of 2 or more. The polymer chain in which the compound represented by the formula (1) and the formula (2) or the formula (3) is used as the raw material composition may be any one, two or more, or all of the polymer chains.

Here, the polyamic acid block polymer may be synthesized by separately producing two or more kinds of polyamic acids, and then mixing and heating the two or more kinds of polyamic acids. Alternatively, two or more kinds of polyamic acids may be synthesized in the same reaction vessel, and then heated, as in the case of synthesizing the first polyamic acid and then adding the raw material of the second polyamic acid to the same reaction vessel.

In the case of producing a block polymer, the compound represented by the formula (1) is preferably 10 mol% or more, more preferably 20 mol% or more, based on the total amount of the acid dianhydrides used as the raw material in the raw material composition used as the raw material for the polymer of the present invention. The compound represented by the formula (2) or (3) is preferably 10 mol% or more, more preferably 20 mol% or more, based on the total amount of diamines used as a raw material.

In addition, the liquid crystal aligning agent of the present invention may further contain a solvent in terms of the coatability of the liquid crystal aligning agent or the adjustment of the concentration of the polyamic acid or derivative thereof. The solvent is not particularly limited as long as it is a solvent having an ability to dissolve the polymer component. The solvent is widely used in the production process or the use of a polymer component such as polyamic acid or soluble polyimide, and may be appropriately selected depending on the purpose of use. The solvent may be one kind or a mixed solvent of two or more kinds.

The solvent may be a parent solvent of the polyamic acid or a derivative thereof or another solvent for the purpose of improving coatability.

As the aprotic polar organic solvent which is a solvent-philic with respect to the polyamic acid or the derivative thereof, there may be mentioned: n-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl imidazolidinone, N-methyl caprolactam, N-methylpropanamide, N-dimethylacetamide, dimethylsulfoxide, N-dimethylformamide, N-diethylformamide, diethylacetamide, N-dimethylisobutyl amide, gamma-butyrolactone, gamma-valerolactone, and the like. Of these, N-methyl-2-pyrrolidone, dimethylimidazolidone, gamma-butyrolactone or gamma-valerolactone is preferable.

Examples of other solvents for the purpose of improving coatability and the like include: ethylene glycol monoalkyl ethers such as ethylene glycol monobutyl ether and ethylene glycol mono-t-butyl ether, diethylene glycol monoalkyl ethers such as diethylene glycol monoethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether and diethylene glycol dialkyl ethers such as diethylene glycol butyl methyl ether. In addition, there may be mentioned: propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether and 1-butoxy-2-propanol, dipropylene glycol monoalkyl ethers such as dipropylene glycol monomethyl ether, triethylene glycol monoalkyl ethers, butyl cellosolve acetate, phenyl acetate, and ester compounds such as these acetates. Further, there may be mentioned: dialkyl malonates such as diethyl malonate, alkyl lactate, diisobutyl ketone, diacetone alcohol, 3-methyl-3-methoxybutanol, 4-methyl-2-pentanol, diisobutyl methanol, tetrahydronaphthalene and isophorone.

Of these, diisobutyl ketone, 4-methyl-2-pentanol, diisobutyl methanol, ethylene glycol monobutyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol monoethyl ether, 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 acetate is preferred.

The concentration of the solid content in the liquid crystal aligning agent of the present invention is not particularly limited, and the optimum value may be selected by combining the following various coating methods. In general, in order to suppress unevenness, pinholes, and the like at the time of coating, the amount is preferably 0.1 to 30% by weight, more preferably 1 to 10% by weight, relative to the varnish weight.

The viscosity of the liquid crystal aligning agent of the present invention varies depending on the method of coating, the concentration of the polyamic acid or derivative thereof, the kind of the polyamic acid or derivative thereof used, and the kind and ratio of the solvent. For example, when the coating is performed by a printer, the thickness is 5 to 100 mPas (more preferably 10 to 80 mPas). When the thickness is 5 mPas or more, a sufficient film thickness is easily obtained, and when the thickness is 100 mPas or less, printing unevenness is easily suppressed. When the coating is performed by spin coating, it is preferably 5 to 200 mPas (more preferably 10 to 100 mPas). When the coating is performed using an inkjet coating apparatus, it is preferably 5 to 50mpa·s (more preferably 5 to 20mpa·s). The viscosity of the liquid crystal aligning agent can be measured by a rotational viscosity measurement method, for example, using a rotational viscometer (TVE-20L type viscometer manufactured by the east machine industry (Co., ltd.) (measurement temperature: 25 ℃ C.).

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

< Alkenyl substituted nadic imide (nadimide) compound >)

For example, the liquid crystal aligning agent of the present invention may further contain an alkenyl-substituted nadic imide compound for the purpose of stabilizing the electric characteristics of the liquid crystal display element for a long period of time. The alkenyl-substituted nadic imide compound may be used singly or in combination. For the above purpose, the content of the alkenyl-substituted nadic imide compound is preferably 1 to 50% by weight, more preferably 1 to 30% by weight, and still more preferably 1 to 20% by weight, relative to the polyamic acid or derivative thereof. The alkenyl-substituted nadic imide compound is preferably a compound soluble in a solvent in which the polyamic acid or derivative thereof used in the present invention is dissolved. Preferred alkenyl-substituted nadic imide compounds include alkenyl-substituted nadic imide compounds disclosed in japanese patent laid-open publication No. 2008-096979, japanese patent laid-open publication No. 2009-109987, and japanese patent laid-open publication No. 2013-242526. As particularly preferred alkenyl-substituted nadic imide compounds, there may be mentioned: bis {4- (allylbicyclo [2.2.1] hept-5-ene-2, 3-dicarboxyimide) phenyl } methane, N '-m-xylylene-bis (allylbicyclo [2.2.1] hept-5-ene-2, 3-dicarboxyimide) or N, N' -hexamethylene-bis (allylbicyclo [2.2.1] hept-5-ene-2, 3-dicarboxyimide).

< Compound having radically polymerizable unsaturated double bond >

For example, the liquid crystal aligning agent of the present invention may further contain a compound having a radical polymerizable unsaturated double bond for the purpose of stabilizing the electrical characteristics of the liquid crystal display element for a long period of time. The compound having a radical polymerizable unsaturated double bond may be one compound or two or more compounds. In addition, the alkenyl-substituted nadic imide compound is not included in the compound having a radical polymerizable unsaturated double bond. Among the compounds having a radical polymerizable unsaturated double bond, preferable compounds include: n, N ' -methylenebisacrylamide, N ' -dihydroxyethylene-bisacrylamide, ethylene bisacrylate, 4' -methylenebis (N, N-dihydroxyethylene-acryiamine), triallyl cyanurate, and compounds having radical-polymerizable unsaturated double bonds disclosed in Japanese patent application laid-open No. 2009-109987, japanese patent application laid-open No. 2013-242526, international publication No. 2014/119682, and International publication No. 2015/152014. For the purpose, the content of the compound having a radical polymerizable unsaturated double bond is preferably 1 to 50% by weight, more preferably 1 to 30% by weight, relative to the polyamic acid or derivative thereof.

< Oxazine (oxazine) Compound >

For example, the liquid crystal aligning agent of the present invention may further contain an oxazine compound for the purpose of stabilizing the electrical characteristics of the liquid crystal display element for a long period of time. 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 to 20% by weight, relative to the polyamic acid or derivative thereof.

The oxazine compound is preferably an oxazine compound which is soluble in a solvent for dissolving the polyamic acid or a derivative thereof and has ring-opening polymerization property. Preferable oxazine compounds include oxazine compounds represented by the formula (OX-3-1), the formula (OX-3-9) and the formula (OX-3-10), and oxazine compounds disclosed in Japanese patent application laid-open No. 2007-286597 and Japanese patent application laid-open No. 2013-242526.

< Oxazoline Compounds >

For example, the liquid crystal aligning agent of the present invention may further contain an oxazoline compound for the purpose of stabilizing the electrical characteristics of the liquid crystal display element for a long period of time. The oxazoline compound is a compound having an oxazoline structure. The oxazoline compound may be one compound or two or more compounds. For the purpose, the content of the oxazoline compound is preferably 0.1 to 50 wt%, more preferably 1 to 40 wt%, and still more preferably 1 to 20 wt% with respect to the polyamic acid or derivative thereof. Preferred oxazoline compounds include those disclosed in japanese patent application laid-open publication No. 2010-054872 and japanese patent application laid-open publication No. 2013-242526. More preferably, 1, 3-bis (4, 5-dihydro-2-oxazolyl) benzene is exemplified.

< Epoxy Compound >

For example, the liquid crystal aligning 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, for the purpose of improving the hardness of the film, or for the purpose of improving the adhesion with the sealant. The epoxy compound may be one kind of compound or two or more kinds of compounds. For the 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 to 10% by weight, relative to the polyamic acid or derivative thereof.

As the epoxy compound, various compounds having one or more epoxy rings in the molecule can be used.

For the purpose of improving the hardness of the film or the adhesion to the sealant, a compound having two or more epoxy rings in the molecule is preferable, and a compound having three or four epoxy rings in the molecule is more preferable.

Examples of the epoxy compound include those disclosed in Japanese patent application laid-open No. 2009-175715, japanese patent application laid-open No. 2013-242526, japanese patent application laid-open No. 2016-170409, and International publication No. 2017/217813. Preferable epoxy compounds include: n, N, N ', N' -tetraglycidyl-4, 4 '-diaminodiphenylmethane, 3-glycidoxypropyl trimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltriethoxysilane, (3, 3',4,4 '-diepoxy) dicyclohexyl, 1, 4-butanediol glycidyl ether, tris (2, 3-epoxypropyl) isocyanurate, 1, 3-bis (N, N-diglycidyl aminomethyl) cyclohexane or N, N' -tetraglycidyl-m-xylylenediamine. More preferable examples thereof include 3-glycidoxypropyl trimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyl trimethoxysilane and 2- (3, 4-epoxycyclohexyl) ethyl triethoxysilane. In addition to the addition, an oligomer or polymer having an epoxy ring may be added. An oligomer or polymer having an epoxy ring can be used as disclosed in Japanese patent application laid-open No. 2013-242526.

< Silane Compound >)

For example, the liquid crystal aligning agent of the present invention may further contain a silane compound for the purpose of improving adhesion to a substrate and a sealant. For the above purpose, the content of the silane compound is preferably 0.1 to 30% by weight, more preferably 0.5 to 20% by weight, and still more preferably 0.5 to 10% by weight, relative to the polyamic acid or derivative thereof.

As the silane compound, a silane coupling agent disclosed in Japanese patent application laid-open No. 2013-242526, japanese patent application laid-open No. 2015-212807, japanese patent application laid-open No. 2018-173545, and International publication No. 2018/181566 can be used. As preferred silane coupling agents, there may be mentioned: 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl triethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyl trimethoxysilane, p-aminophenyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3-glycidoxypropyl methyldiethoxysilane, 3-isocyanatopropyl triethoxysilane or 3-ureidopropyl triethoxysilane.

In addition to the above-described additives, a compound having a cyclic carbonate group, a compound having a hydroxyalkylamide moiety, or a hydroxyl group may be added for the purpose of improving the strength of an alignment film or for the purpose of stabilizing the electrical characteristics of a liquid crystal display element for a long period of time. Specific examples of the compound include those disclosed in Japanese patent laid-open publication No. 2016-118753 and International publication No. 2017/110976. Preferable examples of the compound include the following formulae (HD-1) to (HD-4). These compounds are preferably 0.5 to 50% by weight, more preferably 1 to 30% by weight, and still more preferably 1 to 10% by weight, relative to the polyamic acid or derivative thereof.

In addition, when it is desired to improve the antistatic property, an antistatic agent may be used, and in the case of imidization at a low temperature, an imidization catalyst may be used. As the imidization catalyst, there may be mentioned imidization catalysts 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 heated and calcined in the process of forming a liquid crystal alignment film, imidization reaction is caused to form a polyimide-based liquid crystal alignment film. The liquid crystal aligning agent of the present invention is suitable for a liquid crystal aligning agent for photo-alignment, and a photo-alignment method can be applied to an alignment treatment in a process of forming a liquid crystal alignment film.

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

The liquid crystal alignment film of the present invention can be obtained by a usual method for 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 subjecting to the following steps: a step of forming a coating film of the liquid crystal aligning agent of the present invention, a step of forming a film of the liquid crystal aligning agent by heat-drying the coating film and a step of applying light to the film of the liquid crystal aligning agent to impart anisotropy, and a step of heating and calcining the film of the liquid crystal aligning agent to which anisotropy is imparted.

The coating film can be formed by applying the liquid crystal aligning agent of the present invention to a substrate in a liquid crystal display element in the same manner as in the production of a usual liquid crystal alignment film. Examples of the substrate include a substrate made of glass, silicon nitride, acrylic, polycarbonate, polyimide, and the like, on which electrodes such as Indium Tin Oxide (ITO), indium zinc Oxide (In ₂O₃ -ZnO, IZO), and Indium gallium zinc Oxide (In-Ga-ZnO ₄, IGZO) electrodes, and the like, and color filters, are provided.

As a method of applying a liquid crystal aligning agent to a substrate, a rotator method, a printing method, a dipping method, a dropping method, an inkjet method, and the like are generally known. These methods can be applied to the present invention as well.

As the heat drying step, a method of performing heat treatment in an oven or an infrared oven, a method of performing heat treatment on a hot plate, and the like are generally known. The heat drying step is preferably performed at a temperature within a range where the solvent can evaporate, and more preferably at a temperature relatively lower than the temperature in the heat calcination step. Specifically, the heating and drying temperature is preferably in the range of 30 to 150 ℃, and more preferably in the range of 50 to 120 ℃.

The heating and calcining step may be performed under conditions required for imidization of the polyamic acid or derivative thereof. As a method for calcining a coating film, a method of heat-treating the coating film in an oven or an infrared oven, a method of heat-treating the coating film on a hot plate, and the like are generally known. These methods can be applied to the present invention as well. It is usually preferable to conduct the reaction at a temperature of about 90℃to 300℃for 1 minute to 3 hours, more preferably 120℃to 280℃and still more preferably 150℃to 250 ℃.

In the case where importance is attached to improving the anisotropy of the film or the afterimage characteristics when manufacturing the liquid crystal display element, it is preferable to slowly raise the temperature in the heating step, for example, the temperature may be raised stepwise, the heating and the calcination may be performed at different temperatures multiple times, or the temperature may be changed from a low temperature to a high temperature to perform the heating. In addition, two heating methods may be combined.

When the heating and calcining are performed at different temperatures, a plurality of heating devices set at different temperatures may be used, or one heating device may be used to sequentially change to different temperatures.

When the heating calcination is performed at a plurality of times at different temperatures, it is preferable to perform the calcination at a first calcination temperature of 90 to 180℃and it is preferable to perform the calcination at a final temperature of 185 to 300 ℃. For example, it is preferable to heat calcine at 220 ℃ after heat calcine at 110 ℃; heating and calcining at 110 ℃ and then heating and calcining at 230 ℃; heating and calcining at 130 ℃ and then heating and calcining at 220 ℃; heating and calcining at 150 ℃ and then heating and calcining at 200 ℃; heating and calcining at 150 ℃ and then heating and calcining at 220 ℃; heating and calcining at 150 ℃ and then heating and calcining at 230 ℃; or heating and calcining at 170 ℃ and then heating and calcining at 200 ℃. Further, it is also preferable to perform the heating and calcination while increasing the stage and gradually increasing the temperature. When the heating temperature is changed and the heating and the calcination are performed in two or more stages, the heating time in each heating step is preferably 5 minutes to 30 minutes.

In the case of calcining the mixture by changing the temperature from a low temperature to a high temperature, the initial temperature is preferably 90 to 180 ℃. The final temperature is preferably 185 to 300 ℃, more preferably 190 to 230 ℃. The heating time is preferably 5 minutes to 60 minutes, more preferably 20 minutes to 60 minutes. The temperature rise rate may be, for example, 0.5 to 40 ℃. The temperature rising speed during the temperature rising may not be fixed.

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

A method for forming a liquid crystal alignment film according to the present invention by a photo-alignment method will be described in detail. The liquid crystal alignment film of the present invention using the photo-alignment method can be formed by: the film obtained by heat-drying the coating film is irradiated with light to impart anisotropy to the film, and the film is heated and calcined. Alternatively, the coating film may be formed by heat-drying, heat-calcining, and then irradiating the film with light.

Further, 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 in the step of heat-drying the coating film or the step of heat-calcining the coating film, or may be performed between the heat-drying step and the heat-calcining step. The heating temperature at the time of irradiation of light in the step of heat-drying the coating film or the step of heat-calcining may be referred to as the description of the heat-drying step or the heat-calcining step. The heating temperature when light is irradiated between the heat drying step and the heat calcining step is preferably in the range of 30 to 150 ℃, and more preferably in the range of 50 to 110 ℃.

As the light used in the light irradiation step in the photo-alignment method, for example, ultraviolet light or visible light including light having a wavelength of 150nm to 800nm can be used. The light is not particularly limited as long as it is light capable of imparting liquid crystal alignment ability to the film, and is preferably polarized light, and more preferably linearly polarized light, when a strong alignment regulating force is to be exerted on the liquid crystal.

The irradiation amount of the polarized light in the light irradiation step is preferably 0.05J/cm ²～10J/cm², more preferably 0.1J/cm ²～5J/cm². The wavelength of the polarized light is preferably changed appropriately according to the compound having a photoreactive structure. When the compound represented by the formula (2) is used, the wavelength of the polarized light is preferably 200nm to 400nm, more preferably 300nm to 400nm. When the compound represented by the formula (3) is used, the wavelength of the polarized light is preferably 150nm to 350nm, more preferably 200nm to 300nm. The irradiation angle of the polarized light to the film surface is not particularly limited, and is preferably as perpendicular as possible to the film surface in view of shortening the alignment treatment time when a strong alignment regulating force for the liquid crystal is to be exhibited. In addition, the liquid crystal alignment film of the present invention can align liquid crystals in a direction perpendicular to the polarization direction of the linearly polarized light by irradiating the linearly polarized light.

As the light source used in the light irradiation step, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a Deep ultraviolet (Deep UV) lamp, a halogen lamp, a metal halide lamp, a high power metal halide lamp, a xenon lamp, a mercury xenon lamp, an excimer lamp, a KrF excimer laser, a fluorescent lamp, a light emitting diode (LIGHT EMITTING diode, LED) lamp, a sodium lamp, a microwave excitation electrodeless lamp (microwave discharged electrodeless lamp), or the like can be used without limitation.

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

The liquid crystal alignment film of the present invention does not require a step of cleaning the calcined or irradiated film with a cleaning liquid, but may be provided with a cleaning step according to the case of other steps. As a cleaning method using the cleaning liquid, there are: brushing (brushing), spraying (jet spray), steam cleaning, ultrasonic cleaning, or the like. These methods may be carried out alone or in combination. As the cleaning liquid, there may be used: pure water; or various alcohols such as methanol, ethanol, isopropanol, etc.; aromatic hydrocarbons such as benzene, toluene, and xylene; halogen solvents such as methylene chloride; ketones such as acetone and methyl ethyl ketone, but are not limited thereto. Of course, these cleaning solutions can be used with sufficiently purified cleaning solutions having few impurities. Such a 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 aligning ability of the liquid crystal alignment film of the present invention, annealing treatment with heat or light may be used before and after the heating and calcining step or before and after irradiation with polarized light or unpolarized light. In the annealing treatment, the annealing temperature is 30-180 ℃, preferably 50-150 ℃ and the time is preferably 1 minute-2 hours. The annealing light used in the annealing treatment includes a UV lamp, a fluorescent lamp, an LED lamp, and the like. The irradiation amount of light is preferably 0.3J/cm ²～10J/cm².

The film thickness of the liquid crystal alignment film of the present invention is not particularly limited, but is preferably 10nm to 300nm, more preferably 30nm to 150nm. 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 ellipsometer (ellipsometer).

The liquid crystal alignment film of the present invention is characterized by having particularly large anisotropy of alignment. 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, evaluation can also be performed by a method using ellipsometry (ellipsometry). Specifically, the retardation value of the liquid crystal alignment film can be measured by a spectroscopic ellipsometer. The retardation value of the film increases in proportion to the degree of orientation of the polymer main chain.

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 application of the liquid crystal composition used for the liquid crystal display element, the composition can be used for the alignment control of the liquid crystal material in all other liquid crystal elements such as a liquid crystal antenna, a dimming window, an optical compensation material, a variable phase shifter and the like. In addition, the liquid crystal alignment film of the present invention has large anisotropy, and thus can be used alone for optical compensation material applications.

< Liquid Crystal display element >)

Next, a liquid crystal display element of the present invention will be described. The liquid crystal display device of the present invention is characterized by having the liquid crystal alignment film of the present invention, and can realize high display quality due to the contrast of the liquid crystal alignment film.

The liquid crystal display element of the present invention will be described in detail. In the liquid crystal display device according to the present invention, the liquid crystal alignment film includes a pair of substrates disposed to face each other, an electrode formed on one or both of the facing surfaces of the pair of substrates, a liquid crystal alignment film formed on the facing surface of each of the pair of substrates, a liquid crystal layer formed between the pair of substrates, a pair of polarizing films provided so as to sandwich the facing substrates, a backlight, and a driving device.

The electrode is not particularly limited as long as it is an electrode formed on one surface of the substrate. Examples of such electrodes include ITO and metal vapor deposited films. The electrode may be formed on the entire surface of one surface of the substrate, or may be formed in a desired shape, for example, by patterning. Examples of the desired shape of the electrode include a comb-shaped structure and a saw-tooth structure. The electrode may be formed on one of a pair of substrates, or may be formed on both substrates. The formation form of the electrode varies depending on the type of the liquid crystal display element, and for example, in the case of an IPS type liquid crystal display element (in-plane switching type liquid crystal display element), the electrode is disposed on one of the pair of substrates, and in the case of the other liquid crystal display element, the electrode is disposed on both of the pair of substrates. The liquid crystal alignment film is formed on the substrate or electrode.

In the case of a liquid crystal display element (for example, IPS, FFS, etc.) having a parallel alignment, the liquid crystal display element has at least a backlight, a first polarizing film, a first substrate, a first liquid crystal alignment film, a liquid crystal layer, a second substrate, and a second polarizing film as a structure from the backlight side, and the polarizing axis of the polarizing film is provided so that the polarizing axis of the first polarizing film (the direction of polarization absorption) intersects (preferably is orthogonal to) the polarizing axis of the second polarizing film. In this case, the polarizing axis of the first polarizing film may be parallel or perpendicular to the liquid crystal alignment direction. A liquid crystal display element disposed so that the polarizing axis of the first polarizing film is parallel to the liquid crystal alignment direction is referred to as an O-mode, and a liquid crystal display element disposed so as to be orthogonal is referred to as an E-mode. The liquid crystal alignment film of the present invention can be applied to either one of the O-mode and the 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 for adding anisotropy to the liquid crystal aligning agent is made to be parallel to and coincident 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 aligning agent of the present invention, the arrangement is made in the O-mode), the transmittance of the liquid crystal aligning film in the light absorption wavelength region increases. Therefore, the transmittance of the liquid crystal display element can be further improved.

The liquid crystal layer is formed by sandwiching the liquid crystal composition between the pair of substrates facing each other on the surface on which the liquid crystal alignment film is formed. In the formation of the liquid crystal layer, spacers which are present between the pair of substrates and form appropriate intervals may be used as needed by using fine particles, resin sheets, or the like.

As a method for forming a liquid crystal layer, a vacuum injection method and a liquid crystal Drop Fill (ODF) method are known.

In the vacuum injection method, a gap (cell gap) is provided so that the liquid crystal alignment film faces each other, and a sealing agent is printed while leaving an injection port of liquid crystal, and the substrate is bonded. A liquid crystal display element is manufactured by injecting a filling liquid crystal into a cell gap defined by a substrate surface and a sealant by a vacuum differential pressure, and then closing the injection port.

In the ODF method, a liquid crystal is dropped in a region of one of a pair of substrates, which is formed by sealing the outer Zhou Yinshua of the liquid crystal alignment film surface, and then the other substrate is bonded so that the liquid crystal alignment film surfaces face 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 cure the sealant, thereby manufacturing a liquid crystal display element.

As the sealant used for bonding the substrates, a UV curing type sealant and a thermal curing type sealant are known. The sealing agent may be printed by, for example, screen printing.

The liquid crystal composition is not particularly limited, and various liquid crystal compositions having positive or negative dielectric anisotropy can be used. Preferred liquid crystal compositions having positive dielectric anisotropy include: liquid crystal compositions disclosed in Japanese patent application laid-open No. 3086228, japanese patent application laid-open No. 2635435, japanese patent application laid-open No. 5-501735, japanese patent application laid-open No. 8-157826, japanese patent application laid-open No. 8-231960, japanese patent application laid-open No. 9-241644 (EP 885272A 1), japanese patent application laid-open No. 9-302346 (EP 806466A 2), japanese patent application laid-open No. 8-199168 (EP 722998A 1), japanese patent application laid-open No. 9-235552, japanese patent application laid-open No. 9-255956, japanese patent application laid-open No. 9-241643 (EP 885271A 1), japanese patent application laid-open No. 10-204016 (EP 844229A 1), japanese patent application laid-open No. 10-204436, japanese patent application laid-open No. 10-231482, japanese patent application laid-open No. 2000-087040, japanese patent application laid-open No. 2001-48822, and the like.

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, japanese patent application laid-open No. 4-224885, japanese patent application laid-open No. 8-40953, japanese patent application laid-open No. 8-104869, japanese patent application laid-open No. 10-168076, japanese patent application laid-open No. 10-168453, japanese patent application laid-open No. 10-236989, japanese patent application laid-open No. 10-236990, japanese patent application laid-open No. 10-236992, japanese patent application laid-open No. 10-236993, japanese patent application laid-open No. 10-236994, japanese patent application laid-open No. 10-237000, japanese patent application laid-open No. 10-237004, japanese patent application laid-open No. 10-237024, japanese patent application laid-open No. 10-237035, japanese patent application laid-open No. 10-237075, japanese patent application laid-open No. 10-237024 Japanese patent application laid-open No. 10-237076, japanese patent application laid-open No. 10-237448 (EP 967261A 1), japanese patent application laid-open No. 10-287874, japanese patent application laid-open No. 10-287875, japanese patent application laid-open No. 10-291945, japanese patent application laid-open No. 11-029581, japanese patent application laid-open No. 11-080049, japanese patent application laid-open No. 2000-256307, japanese patent application laid-open No. 2001-019965, japanese patent application laid-open No. 2001-192657, japanese patent application laid-open No. 2010-037428, international publication No. 2011/024366, international publication No. 2010/072370, japanese patent application laid-open No. 2010-537010, japanese patent application laid-open No. 2012-077201, A liquid crystal composition disclosed in japanese patent laid-open publication No. 2009-084362 and the like.

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

In addition, for example, from the viewpoint of improving the alignment property, the liquid crystal composition used in the liquid crystal display element of the present invention may further contain additives. Such additives are photopolymerizable monomers, optically active compounds, antioxidants, ultraviolet absorbers, pigments, defoamers, polymerization initiators, polymerization inhibitors, and the like. Preferred examples of the photopolymerizable monomer, optically active compound, antioxidant, ultraviolet absorber, pigment, defoamer, polymerization initiator and polymerization inhibitor include those disclosed in International publication No. 2015/146330.

In order to be suitable for a liquid crystal display element of a polymer stabilized alignment (polymer sustained alignment, PSA) mode, a compound capable of polymerizing may be mixed in the liquid crystal composition. Preferable examples of the polymerizable compound are compounds having a polymerizable group such as acrylate, methacrylate, vinyl compound, vinyloxy compound, propenyl ether, epoxy compound (oxetane ) and vinyl ketone. Preferred compounds include those disclosed in International publication No. 2015/146330 and the like.

Examples (example)

The present invention will be described below with reference to examples. The evaluation methods and compounds used in the examples are as follows.

Weight average molecular weight (Mw)

The weight average molecular weight of the polyamic acid was determined by: the sample was measured by GPC using a 2695 separation module 2414 differential refractometer (manufactured by Waters), and converted into polystyrene. The obtained polyamic acid was diluted with a mixed solution of phosphoric acid-Dimethylformamide (DMF) (phosphoric acid/dmf=0.6/100:weight ratio) so that the concentration of the polyamic acid became about 2 wt%. The column was subjected to measurement using HSPgel RT MB-M (manufactured by Waters) as a developing solvent at a column temperature of 50℃and a flow rate of 0.40 mL/min. The standard polystyrene used was TSK standard polystyrene manufactured by Tosoh (Stro).

< Alternating current (ALTERNATING CURRENT, AC) afterimage determination/contrast determination >)

The AC afterimage was measured according to the method described in International publication No. 2000/43833.

Specifically, the luminance-voltage characteristics (B-V characteristics) of the produced liquid crystal cell were measured, and the measured luminance-voltage characteristics were used as the luminance-voltage characteristics before stress application: b (before). Subsequently, an alternating current of 4.5V and 60Hz was applied to the liquid crystal cell for 20 minutes, followed by short-circuiting for 1 second, and the luminance-voltage characteristics (B-V characteristics) were measured again. This was set as luminance-voltage characteristics after stress application: b (after). Here, the luminance change rate Δb (%) was obtained by using the luminance at a voltage of 1.3V for each luminance-voltage characteristic measured and using the following formula. The smaller the value of Δb (%) is, the more the generation of AC afterimage can be suppressed, that is, the better the afterimage characteristics are.

If Δb is 3% or less, it can be said that the afterimage characteristics are good, but in recent years, the demand for the afterimage characteristics is further improved, preferably lower.

Δb (%) = { [ B (after)) -B (before)) ]/B (before)) } ×100

AC afterimages were evaluated according to the following criteria.

The AC afterimage is 3% or less: o (circle)

AC afterimage is less than 3%: x-shaped glass tube

The Contrast Ratio (CR) was obtained using the Ratio of the minimum luminance to the maximum luminance in the B-V characteristic before stress application. The larger the CR value is, the more vivid the dark display is indicated and the better the contrast is.

CR=B (front) _max/B (front) _min

Where B (before) _max represents the maximum luminance in the B-V characteristic before stress application and B (before) _min represents the minimum luminance in the B-V characteristic before stress application.

Contrast (CR) was evaluated according to the following criteria.

CR is 3000 or more: o (circle)

CR is less than 3000: x-shaped glass tube

< Evaluation of Voltage Holding Rate (VHR) reliability >)

The Voltage Holding Ratio (VHR) of the liquid crystal display element was measured by applying a rectangular wave having a wave height of ±5v to the cell at 60 ℃ according to the method described in "water island or the like, draft set p78 of the 14 th liquid crystal discussion (1988)". The VHR at this time is set to VHR (before). The voltage holding ratio is an index indicating how much the applied voltage is held after the frame period, and if the value is 100%, it means that all the charges are held. The unit was exposed to an LED backlight for 300 hours and VHR was again determined. The VHR at this time is referred to as VHR (after). The VHR reliability was evaluated by using a VHR reduction rate calculated using the following formula. It can be said that the smaller the VHR decrease rate, the higher the VHR reliability and the higher the stability to light.

VHR reduction Rate (%)

= |{ [ VHR (post)) -VHR (pre (before)) ]/VHR (pre (before)) } ×100|

The VHR reliability was evaluated for the single layer type alignment film and the blend type alignment film according to the following criteria.

Single layer type orientation film

VHR reduction less than 5%: o (circle)

The VHR reduction rate was 5% or more: x-shaped glass tube

Blend type orientation film

VHR reduction less than 3%: o (circle)

The VHR reduction rate was 3% or more: x-shaped glass tube

< Tetracarboxylic dianhydride >)

< Diamine >

< Solvent >

NMP: n-methyl-2-pyrrolidone (N-methyl-2-pyrrolidone)

BC: butyl Cellosolve (Butyl Cellosolve) (ethylene glycol monobutyl ether)

< Additive >)

Additive 1:1, 3-bis (4, 5-dihydro-2-oxazolyl) benzene

The compound represented by the formula (1-1-1) is obtained by the method described in International publication No. 2014/046180.

The compound represented by the formula (3-4-1) is a compound in which two esters on the cyclopropane ring of the formula (3-4) are in a trans configuration. The compound represented by the formula (3-4-1) is obtained by a method described in Japanese patent application laid-open No. 2021-187841.

Preparation of varnish

The varnish used in this example was prepared according to the following procedure. The varnishes A1 to A6 and the varnishes R1 to R4 prepared in preparation examples 1 to 10 are solutions of polyamic acid obtained by reacting at least one compound having a photoreactive chemical structure as a raw material. These varnishes exhibit anisotropy in films by irradiation of polarized light of an appropriate wavelength after film formation. The blending varnishes B1 to B4 prepared in preparation examples 11 to 14 are solutions of polyamic acids obtained without using a compound having a photoreactive chemical structure as a raw material, and are blended with varnishes A1 to A6 or varnishes R1 to R4 to prepare blending type liquid crystal aligning agents (aligning agents 7 to 12, aligning agents 5 and aligning agents 6 to be described later).

Preparation example of varnish A1 preparation

Into a 100mL three-necked flask equipped with stirring blades and a nitrogen inlet tube, 1.757g of the compound represented by the formula (2-1-1) was placed, and 34.0g of N-methyl-2-pyrrolidone was added and stirred. 2.561g of the compound represented by the formula (1-1-1) and 1.682g of the compound represented by the formula (AN-4-17) (m=8) were added to the solution under nitrogen atmosphere, and stirred at room temperature for 12 hours. To this, 40.0g of NMP and 20.0g of BC were added, and the resulting solution was heated and stirred at 60℃until the weight average molecular weight of the polymer as a solute became a desired weight average molecular weight, thereby obtaining varnish A1 having a solute weight average molecular weight of about 13,500 and a resin component concentration (solid component concentration) of 6 wt%.

[ Preparation example 2 to preparation example 14 of varnishes ] preparation of varnishes A2 to A6, R1 to R4, B1 to B4

Varnishes A2 to a varnish A6 having a solid content of 6% by weight and varnishes R1 to R4 for comparison were prepared in the same manner as in preparation example 1 except that the compounds used as the diamine and the tetracarboxylic dianhydride were changed as shown in table 1. Varnishes B1 to B4 were prepared in the same manner as in preparation example 1, except that the compounds used as diamines and tetracarboxylic dianhydrides were changed as shown in table 2. In the varnishes B1 to B4, the conditions of heating and stirring were adjusted so that the weight average molecular weight of the polymer became about 50,000. The weight average molecular weight of the polymer produced is shown in tables 1 and 2. In table 1, the examples in which two or more compounds are described as diamines refer to the case where all the compounds are used as diamines in combination, and the examples in which two or more compounds are described as tetracarboxylic dianhydrides refer to the case where all the compounds are used as tetracarboxylic dianhydrides in combination. The values in brackets indicate the formulation ratio (mol%), and blank refers to the absence of the compound corresponding to the column. The same is true in table 2.

TABLE 1

TABLE 2

Example 1

< Preparation of liquid Crystal alignment agent >

The varnish A1 was diluted and stirred with an NMP/BC mixed solution (NMP/bc=7/3 weight ratio) so that the solid content concentration became 4 weight%, to prepare an alignment agent 1.

Contrast measurement and AC afterimage measurement

The prepared alignment agent 1 was coated on a glass substrate with FFS electrodes and a glass substrate with column spacers (column spacers) by a rotator method. After the coating, the substrate was heated at 60℃for 80 seconds to evaporate the solvent, and then linear polarization of ultraviolet rays was irradiated with a Mullett-Light (ML-501C/B) produced by a cattle tail motor (stock) through a polarizing plate having a polarization wavelength range of 300nm to 450nm and a short-wavelength cut-off filter having a cut-off wavelength of 280nm from a direction perpendicular to the substrate. The exposure energy at this time was measured by using an ultraviolet cumulative light meter UIT-150 (light receiver: UVD-S365) manufactured by a cattle tail motor (stock), and the exposure time was adjusted so that the light quantity became 2.0.+ -. 0.1J/cm ² at a wavelength of 365 nm. Thereafter, calcination treatment was performed at 220℃for 30 minutes, thereby forming an alignment film having a film thickness of about 100 nm. Then, these two substrates on which the alignment films are formed are bonded 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 provided between the facing liquid crystal alignment films. At this time, the polarization directions of the linearly polarized light irradiated to the respective liquid crystal alignment films are made parallel. These cells were filled with the positive type liquid crystal composition A to prepare liquid crystal cells (liquid crystal display elements) having a cell thickness of 5. Mu.m.

Positive liquid crystal composition A >

(Physical Property values)

Phase transition temperature NI: dielectric constant anisotropy Δε at 100.1deg.C: 5.1, refractive index anisotropy Δn:0.093, viscosity η:25.6 mPas.

Using the produced liquid crystal cell, AC afterimage measurement and contrast measurement were performed according to the evaluation method "AC afterimage measurement/contrast measurement".

The AC residual images and contrast evaluation results of examples 1 to 12 and comparative examples 1 to 6 are shown in tables 3 and 4.

< VHR reliability evaluation >)

The alignment agent 1 was coated on the glass substrate with IPS electrode and the glass substrate with column spacers by a rotator method. After the coating, the substrate was heated at 60℃for 80 seconds to evaporate the solvent, and then linear polarization of ultraviolet rays was irradiated with a Mullett-Light (ML-501C/B) produced by a cattle tail motor (stock) through a polarizing plate having a polarization wavelength range of 300nm to 450nm and a short-wavelength cut-off filter having a cut-off wavelength of 280nm from a direction perpendicular to the substrate. The exposure energy at this time was measured by using an ultraviolet cumulative light meter UIT-150 (light receiver: UVD-S365) manufactured by a cattle tail motor (stock), and the exposure time was adjusted so that the light quantity became 2.0.+ -. 0.1J/cm ² at a wavelength of 365 nm. Thereafter, calcination treatment was performed at 220℃for 30 minutes, thereby forming a liquid crystal alignment film having a film thickness of about 100 nm.

Then, the two substrates on which the liquid crystal alignment films are formed are bonded so that the surfaces on which the liquid crystal alignment films are formed face each other and so that a gap for injecting the liquid crystal composition is formed between the facing liquid crystal alignment films. In this case, the orientation of the substrate is set to be such that the polarization directions of the linearly polarized light irradiated to the liquid crystal alignment films are parallel to each other during the photo-alignment process. A negative type 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) having a cell thickness of 7 μm.

Negative type liquid crystal composition A >

(Physical Property values)

Phase transition temperature NI: dielectric constant anisotropy Δε at 75.7deg.C: -4.1, refractive index anisotropy Δn:0.101, viscosity η:14.5 mPas.

Using the produced liquid crystal cell, VHR reliability evaluation was performed according to the evaluation method "evaluation of Voltage Holding Ratio (VHR) reliability". The evaluation results of VHR reliability of examples 1 to 12 and comparative examples 1 to 6 are shown in tables 3 and 4.

Example 2

An alignment agent 2 was prepared in the same manner as in example 1, except that varnish A2 was used instead of varnish A1, and additive 1 was added so as to be 5 parts by weight relative to the solid content while adding NMP/BC mixed solution. A liquid crystal cell was produced in the same manner as in example 1 for the alignment agent 2, and AC afterimage measurement, contrast measurement, and VHR reliability evaluation were performed.

Example 3, comparative example 1, comparative example 2

An alignment agent 3, a comparative alignment agent 1, and a comparative alignment agent 2 were prepared in the same manner as in example 1, except that the varnishes shown in table 3 were used instead of varnish A1. A liquid crystal cell was produced in the same manner as in example 1 for the alignment agent 3, the comparative alignment agent 1, and the comparative alignment agent 2, and AC afterimage measurement, contrast measurement, and VHR reliability evaluation were performed.

Examples 4 to 6, comparative examples 3 and 4

Alignment agents 4 to 6 and comparative alignment agents 3 and 4 were prepared in the same manner as in example 1 except that the varnishes shown in table 3 were used instead of varnish A1. A liquid crystal cell was produced in the same manner as in example 1, except that the alignment agents 4 to 6 and the comparative alignment agents 3 and 4 were irradiated with linearly polarized light of ultraviolet light from a polarizing plate having a polarized light wavelength range of 230nm to 310nm in a direction perpendicular to the substrate, the amount of light was measured by using an ultraviolet cumulative light meter uict-150 (light receiver: UVD-S254) manufactured by a bulltail motor (strand) for exposure energy, and the exposure time of the linearly polarized light was adjusted so as to be 0.5±0.1J/cm ² at the wavelength 254nm, and AC afterimage measurement, contrast measurement, and VHR reliability evaluation were performed.

Example 7

The weight ratio of varnish A1 to varnish B1 was 3:7 to obtain a blended varnish having a solid content concentration of 6% by weight. Further, the alignment agent 7 was prepared by diluting and stirring the NMP/BC mixed solution (NMP/bc=7/3 weight ratio) so that the solid content concentration became 4 weight%. A liquid crystal cell was produced in the same manner as in example 1 except that the alignment agent 7 was used instead of the alignment agent 1, and AC afterimage measurement, contrast measurement, and VHR reliability evaluation were performed.

Example 8

An alignment agent 8 was prepared in the same manner as in example 7, except that varnish A2 was used instead of varnish A1, and additive 1 was added so as to be 5 parts by weight with respect to the solid content at the same time as adding the NMP/BC mixed solution. A liquid crystal cell was produced in the same manner as in example 1 for the alignment agent 8, and AC afterimage measurement, contrast measurement, and VHR reliability evaluation were performed.

Example 9, comparative example 5

An alignment agent 9 and a comparative alignment agent 5 were prepared in the same manner as in example 7, using the varnishes shown in table 4 instead of varnish A1 and varnish B1. A liquid crystal cell was produced in the same manner as in example 1 for each of the alignment agent 9 and the comparative alignment agent 5, and AC afterimage measurement, contrast measurement, and VHR reliability evaluation were performed.

Examples 10 to 12 and comparative example 6

Using the varnishes shown in table 4 instead of varnish A1 and varnish B1, alignment agents 10 to 12 and comparative alignment agent 6 were prepared in the same manner as in example 7. For each of the alignment agents 10 to 12 and the comparative alignment agent 6, a liquid crystal cell was produced in the same manner as in example 4, and AC afterimage measurement, contrast measurement, and VHR reliability evaluation were performed.

TABLE 3

TABLE 4

Evaluation of AC afterimage and contrast of "Σ" in examples 1 to 12. A liquid crystal display element exhibiting excellent residual image characteristics and contrast is obtained by using a polymer containing a tetracarboxylic acid derivative represented by the formula (1) as a raw material as a liquid crystal aligning agent. On the other hand, in comparative example 3, since the formula (AN-4-21) having no biphenyl skeleton was used, a liquid crystal display element exhibiting excellent AC afterimage and contrast could not be obtained. In comparative examples 1 and 5 in which the formula (AN-4-33) having only one benzene ring in the central skeleton was used, the contrast was also x, and as a result, the contrast was inferior to that of the example using the formula (1).

Evaluation of VHR reliability in examples 1 to 12 was ". Smallcircle". A liquid crystal display element excellent in VHR reliability is obtained by using a polymer containing a tetracarboxylic acid derivative represented by the formula (1) as a raw material as a liquid crystal aligning agent. On the other hand, in comparative examples 2,4 and 6, in which the biphenyl structure is present in the central skeleton but the biphenyl moiety is not substituted in the formula (AN-4-37), the electron conjugation of the polyimide chain is not suppressed because no torsion is generated in the benzene ring of the biphenyl structure, and thus a liquid crystal display element exhibiting excellent VHR reliability cannot be obtained. Further, VHR (front) which is VHR before exposure of the LED backlight of each of examples 1 to 12 is 90% or more, and shows sufficient VHR characteristics.

[ Industrial applicability ]

The liquid crystal alignment film formed by using the liquid crystal alignment agent of the present invention can provide a liquid crystal display element having excellent contrast and afterimage characteristics, and can maintain a high voltage holding ratio without deteriorating display quality even when exposed to strong light for a long period of time. The liquid crystal aligning agent of the present invention can be suitably applied to a transverse electric field type liquid crystal display element. In addition, by using the liquid crystal aligning agent of the present invention, a liquid crystal alignment film having high anisotropy can be obtained, and the liquid crystal alignment film can be used for optical compensation materials and the like.

Claims

1. A liquid crystal aligning agent comprising at least one polymer and a solvent, wherein the at least one polymer is a polymer obtained by reacting a tetracarboxylic acid derivative containing at least one selected from the group consisting of a compound represented by the formula (1) and a derivative compound thereof with a diamine;

2. The liquid crystal aligning agent according to claim 1, wherein the raw material composition used as a raw material of the polymer obtained by reacting a tetracarboxylic acid derivative with a diamine comprises at least one compound selected from the group consisting of a compound represented by formula (1) and a derivative compound thereof, and a compound having a photoreactive structure for imparting liquid crystal alignment to an alignment film by photoreaction.

3. The liquid crystal aligning agent according to claim 2, wherein the photoreaction is at least one of photoisomerization, photofries rearrangement, photodecomposition, and photodimerization.

4. The liquid crystal aligning agent according to claim 2, wherein the compound having a photoreactive structure is at least one of compounds represented by formula (2);

5. The liquid crystal aligning agent according to claim 4, wherein the compound represented by the formula (2) is any one of the formulas (2-1) to (2-3);

6. The liquid crystal aligning agent according to claim 2, wherein the compound having a photoreactive structure is at least one of compounds represented by formula (3);

In the formula (3), R ¹ and R ² each independently represent hydrogen, halogen, alkyl having 1 to 6 carbon atoms, haloalkyl having 1 to 6 carbon atoms or alkoxy having 1 to 6 carbon atoms, R ¹ and R ² may be integrated to form a methylene group which may be substituted, X each independently represents halogen, alkyl having 1 to 6 carbon atoms, haloalkyl having 1 to 6 carbon atoms or alkoxy having 1 to 6 carbon atoms, and n independently represents an integer of 0 to 4.

7. The liquid crystal aligning agent according to any one of claims 1 to 6, wherein the compound represented by formula (1) is represented by formula (1-1-1);

8. a liquid crystal alignment film formed from the liquid crystal alignment agent according to any one of claims 1 to 7.

9. A liquid crystal element having the liquid crystal alignment film according to claim 8.

10. A method for manufacturing a liquid crystal alignment film, comprising: a process of applying the liquid crystal aligning agent according to any one of claims 2 to 7 to a substrate; and irradiating the coating film with polarized ultraviolet rays.