Liquid crystal alignment agent for forming a liquid crystal alignment film by a photo-alignment method, liquid crystal alignment film, and liquid crystal device using the same

Abstract

To provide a liquid crystal aligning membrane capable of forming a liquid crystal display element with excellent display quality, which has excellent contrast even in a case where exposure energy for optical aligning processing is small, and provide a liquid crystal aligning agent for optical alignment capable of forming such liquid crystal aligning membrane.SOLUTION: A liquid crystal aligning agent for optical alignment contains at least one polymer and a solvent, where at least one of the polymers is a polymer obtained by reacting tetracarboxylic dianhydrides with diamines. The liquid crystal aligning agent comprises: a raw material composition used as a raw material for the polymer obtained by reacting tetracarboxylic dianhydrides represented by a specific general structural formula with diamines; and a compound having a photoreactive structure that imparts liquid crystal orientation to an aligning membrane by a photoreaction.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal element using the same. More specifically, the present invention relates to a liquid crystal alignment agent for photo-alignment (hereinafter sometimes abbreviated as liquid crystal alignment agent) for forming a liquid crystal alignment film of a photo-alignment type (hereinafter sometimes abbreviated as a photo-alignment film), a liquid crystal alignment film of a photo-alignment type formed using the liquid crystal alignment agent, and a liquid crystal display element having the liquid crystal alignment film. [Background technology]

[0002] There are known liquid crystal elements that can cause optical phenomena such as refraction, scattering, and reflection of electromagnetic waves incident on the element by controlling or modulating the alignment state of the liquid crystal layer in the element. Specifically, in addition to the liquid crystal display elements described below, liquid crystal antennas, light control windows, optical compensation materials, and variable phase shifters are known.

[0003] Liquid crystal display elements are known to have various driving methods, such as TN (Twisted Nematic) mode, STN (Super Twisted Nematic) mode, IPS (In-Plane Switching) mode, FFS (Fringe Field Switching) mode, and vertical alignment type VA (Multi-domain Vertical Alignment) mode. These liquid crystal display elements are applied to image display devices of various electronic devices such as televisions and mobile phones, and development is being carried out with the aim of further improving the display quality. Specifically, the performance of liquid crystal display elements is improved not only by improving the driving method and element structure, but also by the components used in the elements. Among the components used in liquid crystal display elements, the liquid crystal alignment film is one of the important materials related to the display quality, and research on this liquid crystal alignment film is being actively carried out in order to meet the demand for high-quality liquid crystal display elements.

[0004] 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 in contact with the liquid crystal layer, and has the function of aligning the liquid crystal molecules constituting the liquid crystal layer with a certain regularity relative to the substrates. By using a liquid crystal alignment film with high liquid crystal alignment properties, a liquid crystal display element with high contrast and improved afterimage characteristics can be realized (see, for example, Patent Documents 1 and 2).

[0005] Currently, solutions (varnishes) in which polyamic acid, soluble polyimide, or polyamic acid ester is dissolved in an organic solvent are mainly used to form such liquid crystal alignment films. To form liquid crystal alignment films using these varnishes, the varnish is applied to a substrate, and the coating is solidified by heating or the like to form a polyimide-based liquid crystal alignment film, and an alignment treatment suitable for the above-mentioned display mode is performed as necessary. As alignment treatment methods, there are a rubbing method in which the surface of the alignment film is rubbed with a cloth or the like to align the direction of the polymer molecules, and a photoalignment method in which the alignment film is irradiated with linearly polarized ultraviolet light to cause photochemical changes such as photoisomerization and dimerization in the polymer molecules to give the film anisotropy. Of these, the photoalignment method has the advantages of being more uniform in alignment than the rubbing method, not scratching the film because it is a non-contact alignment treatment method, and reducing causes of display defects in liquid crystal display elements such as dust generation and static electricity.

[0006] As examples of liquid crystal alignment films produced using such photo-alignment methods, Patent Documents 1 to 6, for example, describe the use of diaminoazobenzene or the like as a raw material and the application of photoisomerization technology to obtain photo-alignment films with large anchoring energy and good liquid crystal alignment properties. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2010-197999 A [Patent Document 2] International Publication No. 2013 / 157463 [Patent Document 3] JP 2005-275364 A [Patent Document 4] JP 2007-248637 A [Patent Document 5] JP 2009-069493 A [Patent Document 6] International Publication No. 2015 / 016118 Summary of the Invention [Problem to be solved by the invention]

[0008] In recent years, the applications of liquid crystal display elements have become diverse, including monitors for personal computers, liquid crystal televisions, displays for mobile phones and smartphones, and medical monitors. There is a demand for better display quality, and contrast is an important characteristic that affects display quality. In addition, in liquid crystal display elements that use liquid crystal alignment films produced using a photo-alignment method, it is required to use liquid crystal alignment films that can produce good contrast even with a short photo-alignment treatment time, i.e., a photo-alignment treatment with low exposure energy, in order to improve the efficiency of liquid crystal display element production.

[0009] Therefore, the present inventors have conducted intensive research with the objectives of providing a liquid crystal alignment film capable of forming a liquid crystal display element having good contrast and excellent display quality even when the exposure energy of the photo-alignment treatment is lower than that of the conventional method, and of providing a liquid crystal alignment agent for photo-alignment capable of forming such a liquid crystal alignment film. [Means for solving the problem]

[0010] As a result of intensive research to solve the above problems, the present inventors have found that by using a compound represented by formula (1-1) or formula (1-2), an alignment film having high liquid crystal alignment properties can be obtained, and that by using this alignment film, a liquid crystal display element having good contrast and excellent display quality can be formed, thereby completing the present invention. The present invention includes the following configurations.

[0011] [1] A liquid crystal alignment agent for photoalignment, comprising at least one polymer and a solvent, wherein at least one of the polymers is a polymer obtained by reacting a tetracarboxylic dianhydride with a diamine, A liquid crystal alignment agent for photo-alignment, comprising at least one compound represented by formula (1-1) or formula (1-2) and a compound having a photoreactive structure that imparts liquid crystal alignment properties to an alignment film by photoreaction, in a raw material composition used as a raw material for the polymer obtained by reacting the tetracarboxylic dianhydrides with the diamines. TIFF0007663449000001.tif8396[2] The liquid crystal alignment agent for photo-alignment according to item 1, wherein the photoreaction is at least one of photoisomerization, photo-fries transition, photodecomposition, and photodimerization. [3] The liquid crystal aligning agent for photo-alignment according to item 1 or 2, wherein the compound having a photoreactive structure is at least one compound represented by formula (2): In formula (2), X is an alkylene group having 1 to 12 carbon atoms. When the alkylene group has 2 or more carbon atoms, the alkylene group is -(CH 2 ) 2 one or more non-adjacent - may be replaced by -O- or -NH-; R a and R b each independently represents a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, a fluorine atom, a methoxycarbonyl group, or a monovalent group represented by formula (P1-1) or formula (P1-2), R c each independently represents a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, a fluorine atom, or a monovalent group represented by formula (P1-1) or formula (P1-2), j is 0 or 1, and a to c each independently represent an integer of 0 to 2, TIFF0007663449000003.tif3283 In formula (P1-1) and formula (P1-2), R 6a , R 7a and R8a each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or a substituted or unsubstituted alkoxycarbonyl group; R 6a , R 7a and R 8a may be the same or different, * represents the bonding position to the benzene ring in formula (2), In formula (2), a group that is not fixed to any of the carbon atoms constituting the ring indicates that the group may be bonded to any position on the ring. [4] The liquid crystal aligning agent for photo-alignment according to item 3, wherein the compound represented by formula (2) is any one of formulas (2-1) to (2-3): TIFF0007663449000004.tif2573 TIFF0007663449000005.tif2589 TIFF0007663449000006.tif2589 In formula (2-1), R 1a and R 1c each independently represents a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2), In formula (2-2), R 2a and R 2b each independently represents a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2), R 2c are each independently a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, or a fluorine atom; X 1 is an alkylene group having 1 to 12 carbon atoms, and when the alkylene group has 2 or more carbon atoms, the -(CH 2 ) 2 one or more non-adjacent - may be replaced with -O- or -NH-, and k is an integer of 0 to 2; In formula (2-3), R 3a each independently represents a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2), R 4 and R 5are each independently a hydrogen atom or a fluorine atom, R 4 and R 5 cannot be a hydrogen atom at the same time, and R 3c are each independently a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, or a fluorine atom; X 1 is an alkylene group having 1 to 12 carbon atoms, and when the alkylene group has 2 or more carbon atoms, the -(CH 2 ) 2 one or more non-adjacent - may be replaced with -O- or -NH-, m is an integer of 0 to 2, TIFF0007663449000007.tif3283 In formula (P1-1) and formula (P1-2), R 6a , R 7a and R 8a each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or a substituted or unsubstituted alkoxycarbonyl group; R 6a , R 7a and R 8a may be the same or different, * represents the bonding position to the benzene ring in formula (2-1), formula (2-2) and formula (2-3), In formulae (2-1), (2-2) and (2-3), a group that is not bonded to any carbon atom constituting a ring indicates that the bond position in the ring is arbitrary. [5] The liquid crystal aligning agent for photo-alignment according to item 1 or 2, wherein the compound having a photoreactive structure is at least one compound represented by formula (3): TIFF0007663449000008.tif30111 In formula (3), R 1 and R 2 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms; R 1 and R 2may be joined together to form an optionally substituted methylene group, each X 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. [6] The liquid crystal aligning agent for photo-alignment according to any one of items 1 to 5, further comprising an additive. [7] The liquid crystal aligning agent for photo-alignment according to item 6, wherein the additive is at least one selected from the group consisting of oxazoline compounds and epoxy compounds. [8] A liquid crystal alignment film formed from the liquid crystal aligning agent for photo-alignment according to any one of items 1 to 7. [9] A liquid crystal element having the liquid crystal alignment film according to item 8.

[10] A method for producing a liquid crystal alignment film, comprising the steps of: applying the liquid crystal aligning agent for photo-alignment according to any one of items 1 to 7 to a substrate; and irradiating the coating with polarized ultraviolet light. Effect of the Invention

[0012] By using the liquid crystal alignment agent for photo-alignment of the present invention, a liquid crystal alignment film having high liquid crystal alignment properties can be obtained even when the exposure energy of the photo-alignment treatment is low. Furthermore, by using this liquid crystal alignment film, it is possible to efficiently realize the manufacture of a liquid crystal display element having good contrast and excellent display quality. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention will be described in detail below. The following description of the constituent elements may be based on a representative embodiment or a specific example, but the present invention is not limited to such an embodiment. The "liquid crystal alignment agent" in the present invention is a liquid crystal alignment agent that can impart anisotropy by irradiating a polarized ultraviolet ray when the film is formed on a substrate, and is sometimes simply referred to as a "liquid crystal alignment agent" or a "liquid crystal alignment agent for photoalignment" in this specification. In addition, in the present invention, "tetracarboxylic dianhydrides" refer to tetracarboxylic dianhydrides, tetracarboxylic diesters, or tetracarboxylic diester dihalides. In addition, in the present invention, diamines and dihydrazides are sometimes referred to as "diamines".

[0014] <Liquid crystal alignment agent for photo-alignment of the present invention> The liquid crystal alignment agent for photo-alignment of the present invention is characterized in that it contains at least one polymer selected from the group consisting of polyamic acid and polyamic acid derivatives, which are obtained by reacting tetracarboxylic dianhydrides with diamines, and contains, as raw materials for the polymer, at least one compound represented by formula (1-1) or formula (1-2) and a compound having a photoreactive structure that imparts liquid crystal alignment properties to the alignment film by photoreaction. In the present invention, the polyamic acid derivative refers to polyimide, partial polyimide, polyamic acid ester, polyamic acid-polyamide copolymer, and polyamideimide. Such a polymer may be referred to as the polymer of the present invention.

[0015] <Compound represented by formula (1-1) or formula (1-2)> The compound represented by formula (1-1) or formula (1-2) used in the polymer contained in the liquid crystal aligning agent of the present invention will be described. TIFF0007663449000009.tif7789

[0016] The tetracarboxylic dianhydrides used in the polymer contained in the liquid crystal aligning agent of the present invention may be all compounds represented by formula (1-1) or formula (1-2), or the compound represented by formula (1-1) and the compound represented by formula (1-2) may be used in combination. Furthermore, other tetracarboxylic dianhydrides described below may be used in combination, and in that case, the content of the other tetracarboxylic dianhydrides is preferably 5 mol % or more, more preferably 20 mol % to 80 mol %, based on the total amount of tetracarboxylic dianhydrides in the monomer.

[0017] In the molecular structure of the compound represented by formula (1-1) or the compound represented by formula (1-2), two dicarboxylic anhydride skeletons are present at the exo position relative to the norbornane ring to which they are bonded. For the compound represented by formula (1-1) or the compound represented by formula (1-2), there are stereoisomers in which one or two dicarboxylic anhydride skeletons are present at the endo position relative to the norbornane ring to which they are bonded. In the polymer using the compound represented by formula (1-1) and the polymer using the compound represented by formula (1-2), the anisotropy exhibited in the liquid crystal alignment film by the alignment treatment is larger than that in the case of using these stereoisomers, and they are more excellent in terms of liquid crystal alignment properties.

[0018] <Compounds with photoreactive structures> A compound having a photoreactive structure used as a raw material for the polymer contained in the liquid crystal alignment agent of the present invention will be described. In this specification, the photoreactive structure refers to a structure that undergoes a photoreaction by irradiation with light containing a specific wavelength band corresponding to the photoreactive structure. Examples of photoreactions include photoisomerization, photo-fries transition, photodecomposition, and photodimerization. By using a compound having a photoreactive structure as a raw material, the photoreactive structure can be incorporated into the polymer. In addition, the compounds listed in this specification as having a photoreactive structure can also be used as raw materials as compounds without a photoreactive structure when light containing a specific wavelength band corresponding to the photoreactive structure is not irradiated in the process of forming an alignment film from a liquid crystal alignment agent.

[0019] In the process of forming a liquid crystal alignment film, when a coating film containing the liquid crystal alignment agent for photo-alignment of the present invention is irradiated with polarized light of a predetermined wavelength, the photoreactive structure of the polymer chains roughly parallel to the polarization direction undergoes a photoreaction, and the components of the polymer chains that are oriented in a specific direction (roughly perpendicular to the polarization direction of the irradiated light) become dominant, resulting in a coating film imparted with anisotropy. This state in which the components of the polymer chains that are oriented in a specific direction become dominant is expressed as the polymer chains being oriented. When the photoalignment film formed by baking this coating film imparted with anisotropy is used in a liquid crystal display element, the interaction between the surface of the oriented film and the liquid crystal molecules results in the liquid crystal molecules being oriented with their major axes aligned in a certain direction (roughly perpendicular to the polarization direction of the irradiated light).

[0020] <Structure that causes photoisomerization reaction> In the present invention, an example of a structure that causes a photoisomerization reaction is a structure having an azobenzene skeleton. In this specification, the structure having an azobenzene skeleton means a structure represented by the following formula (A). TIFF0007663449000010.tif1684 In formula (A), * represents a bond, and the bonding positions of the bonds on the benzene ring are each independently arbitrary, and a substitutable hydrogen atom on the benzene ring may be replaced with a substituent.

[0021] The compound having an azobenzene structure used in the polymer contained in the photo-alignment liquid crystal aligning agent of the present invention is specifically a compound represented by formula (2). TIFF0007663449000011.tif36121 In formula (2), X is an alkylene group having 1 to 12 carbon atoms. When the alkylene group has 2 or more carbon atoms, the alkylene group is —(CH 2 ) 2 one or more non-adjacent - may be replaced by -O- or -NH-; R a and R beach independently represents a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, a fluorine atom, a methoxycarbonyl group, or a monovalent group represented by formula (P1-1) or formula (P1-2), R c each independently represents a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, a fluorine atom, or a monovalent group represented by formula (P1-1) or formula (P1-2), j is 0 or 1, and a to c each independently represent an integer of 0 to 2, TIFF0007663449000012.tif3283 In formula (P1-1) and formula (P1-2), R 6a , R 7a and R 8a each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or a substituted or unsubstituted alkoxycarbonyl group; R 6a , R 7a and R 8a may be the same or different, * represents the bonding position to the benzene ring in formula (2), In formula (2), a group that is not fixed to any of the carbon atoms constituting the ring indicates that the group may be bonded to any position on the ring.

[0022] The compound represented by formula (2) is specifically the compound represented by the following formulae (2-1) to (2-3). TIFF0007663449000013.tif2573 TIFF0007663449000014.tif2589 TIFF0007663449000015.tif2589 In formula (2-1), R 1a and R 1c each independently represents a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2), In formula (2-2), R 2a and R 2beach independently represents a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2); R 2c are each independently a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, or a fluorine atom; X 1 is an alkylene group having 1 to 12 carbon atoms, and when the alkylene group has 2 or more carbon atoms, the -(CH 2 ) 2 one or more non-adjacent - may be replaced with -O- or -NH-, and k is an integer of 0 to 2; In formula (2-3), R 3a each independently represents a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2); R 4 , R 5 are each independently a hydrogen atom or -F, R 4 and R 5 cannot be a hydrogen atom at the same time, and R 3c are each independently a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, or a fluorine atom; X 1 is an alkylene group having 1 to 12 carbon atoms, and when the alkylene group has 2 or more carbon atoms, the -(CH 2 ) 2 one or more non-adjacent - may be replaced with -O- or -NH-, m is an integer of 0 to 2, TIFF0007663449000016.tif3283 In formula (P1-1) and formula (P1-2), R 6a , R 7a and R 8a each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or a substituted or unsubstituted alkoxycarbonyl group; R 6a , R 7a and R 8a may be the same or different, * represents the bonding position to the benzene ring in formula (2-1), formula (2-2) and formula (2-3), In formulae (2-1), (2-2) and (2-3), a group that is not bonded to any carbon atom constituting a ring indicates that the bond position in the ring is arbitrary.

[0023] Specific examples of the compound represented by formula (2-1) include the following compounds. TIFF0007663449000017.tif66117 In formula (2-1-2), R 6a is an alkyl group having 1 to 4 carbon atoms.

[0024] Specific examples of the compound represented by formula (2-2) include the following compounds. TIFF0007663449000018.tif117142 In formulas (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.

[0025] Specific examples of the compound represented by formula (2-3) include the following compounds. TIFF0007663449000019.tif41140 In the formulas (2-3-1) and (2-3-2), l is an integer of 1 to 10.

[0026] When the transparency of the formed liquid crystal alignment film is important, it is preferable to use one or more compounds selected from the group consisting of formulas (2-1-2), (2-1-3), (2-2-3), (2-2-4), (2-2-5), and (2-2-6), more preferably formula (2-1-2) or formula (2-1-3), and in formula (2-1-2), R 6a Particularly preferred are compounds in which the aryl group is an ethyl group.

[0027] In the case where it is important to obtain a liquid crystal alignment film capable of forming an element having good afterimage characteristics even with a small amount of energy during alignment treatment (i.e., a liquid crystal alignment agent having high sensitivity), it is preferable to use one or more compounds selected from the group consisting of formula (2-1-2), formula (2-1-3), formula (2-2-3), 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 in formula (2-1-2), R 6a is an ethyl group or a compound represented by formula (2-3-1), where l=2 to 6, is more preferred.

[0028] In the case where emphasis is placed on obtaining a liquid crystal display element that maintains a high voltage holding ratio even in long-term use (i.e., has excellent VHR reliability), it is preferable to use one or more compounds selected from the group consisting of formulas (2-1-2), (2-1-3), (2-2-1), (2-2-2), (2-2-3), (2-2-4), (2-2-5), and (2-2-6), and more preferable are compounds represented by formula (2-1-2), (2-1-3), or (2-2-1) where l=2 to 6, and more preferable are compounds represented by formula (2-1-2), (2-1-3), or (2-2-1) where R 6a A compound in which l is an ethyl group or a compound represented by formula (2-2-1), in which l=2 to 6, is more preferred.

[0029] When emphasis is placed on obtaining a liquid crystal display element with higher contrast, it is more preferable to use one or more compounds selected from the group consisting of formulas (2-1-1), (2-2-1), and (2-2-2), and more preferable to use a compound in formula (2-1-1) or (2-2-1) where l is 2 to 6. In this case, the total content of the compounds selected from the group consisting of formulas (2-1-1), (2-2-1), and (2-2-2) in the polymer is preferably 20 mol % to 100 mol %, and more preferably 40 mol % to 100 mol %, based on the total amount of diamines in the monomer.

[0030] <Compounds with structures that cause photo-Fries transition reaction> In the present invention, an example of a structure that causes a photo-fries transition reaction is a structure having a phenyl ester skeleton. In this specification, the structure having a phenyl ester skeleton means a structure represented by the following formula (B). TIFF0007663449000020.tif2273 In formula (B), * is a bond, the bond to the benzene ring may be at any position, and the substitutable hydrogen atom of the benzene ring may be replaced with a substituent. A preferred example of a compound having a structure that causes a photo-induced Friess transition, which is used in the polymer contained in the liquid crystal aligning agent of the present invention, is represented by the following formula (3). Other examples of compounds having a structure that causes a photo-induced Friess transition reaction include compounds represented by formulas (AN-4-32) to (AN-4-36), (DI-5-32), (DI-5-33), (DI-5-35), and (DI-6-8) to (DI-6-10). TIFF0007663449000021.tif2683 TIFF0007663449000022.tif94158 TIFF0007663449000023.tif69140 TIFF0007663449000024.tif61168 In formula (3), R 1 and R 2 R each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. 1 and R 2 may be joined together to form an optionally substituted methylene group. Each X 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 represents an integer from 0 to 4. In formula (DI-5-35), m represents an integer from 0 to 12.

[0031] Among these, from the viewpoint of producing a liquid crystal display element having high contrast, it is preferable to use a compound represented by formula (3), and it is more preferable to use a compound in which the amino groups on each benzene ring in formula (3) are located at the para position relative to the ester group.

[0032] The total content of the compounds represented by formula (3) is preferably 40 mol % to 100 mol %, and more preferably 70 mol % to 100 mol %, based on the total amount of diamines in the monomer.

[0033] Specific examples of the compound represented by formula (3) include the compounds represented by the following formulas (3-1) to (3-6). TIFF0007663449000025.tif69170

[0034] <Structure that causes photodecomposition reaction> In the present invention, an example of a structure that causes a photodecomposition reaction is a structure having a cyclobutanetetracarboxylic acid skeleton. In this specification, the structure having a cyclobutanetetracarboxylic acid skeleton means a structure represented by the following formula (C). TIFF0007663449000026.tif3689 In formula (C), *1, *1', *2 and *2' are bonds, and either or both of the pair of *1 and *1' and the pair of *2 and *2' may be bonded to the same O. That is, they may form an acid anhydride -CO-O-CO-. R b1 , R b2 , R b3 and R b4 are each independently a monovalent organic group.

[0035] Preferred examples of the compound having a structure that undergoes a photodecomposition reaction and is used for the polymer contained in the liquid crystal aligning agent of the present invention include compounds represented by the following formulae (PA-1) to (PA-6). TIFF0007663449000027.tif77147 In formulas (PA-3) to (PA-6), R11 are independently an alkyl group having 1 to 5 carbon atoms.

[0036] <Structure that causes photodimerization reaction> In the present invention, an example of a structure that causes a photodimerization reaction is a structure having a cinnamic acid skeleton. In this specification, the structure having a cinnamic acid skeleton refers to a structure represented by the following formula (D). TIFF0007663449000028.tif3291 In formula (D), * represents a bond, and the bond may be attached to the benzene ring at any position, and any substitutable hydrogen atom on the benzene ring may be replaced with a substituent.

[0037] Preferred examples of the compound having a structure that undergoes a photodimerization reaction and is used in the polymer contained in the liquid crystal aligning agent of the present invention include the compounds represented by the following formulae (PDI-9) to (PDI-13). In the TIFF0007663449000029.tif87142 formula (PDI-12), R 12 is an alkyl group or alkoxy group having 1 to 10 carbon atoms, and at least one hydrogen atom of the alkyl group or alkoxy group may be replaced with a fluorine atom.

[0038] <Type of polymer> The polyamic acid and the polyamic acid derivatives will be described in detail below.

[0039] Here, the polyamic acid is a polymer synthesized by a polymerization reaction between a diamine represented by formula (DI) and a tetracarboxylic dianhydride represented by formula (AN), and has a constitutional unit represented by formula (PAA). When a liquid crystal alignment agent containing a polyamic acid is heated and baked in the process of forming a liquid crystal alignment film, the polyamic acid is imidized, and a polyimide liquid crystal alignment film having a constitutional unit represented by formula (PI) can be formed. TIFF0007663449000030.tif37139 TIFF0007663449000031.tif3742

[0040] In formula (AN), formula (PAA), and formula (PI), X 1 is a tetravalent organic group. In formula (DI), formula (PAA), and formula (PI), X 2 is a divalent organic group. X 1 For the preferred range and specific examples of the tetravalent organic group in X, reference can be made to the corresponding structure of the tetracarboxylic dianhydride in formula (1) or the other tetracarboxylic dianhydrides listed below. 2 For the preferred range and specific examples of the divalent organic group in, reference can be made to the description of the corresponding structure of the diamine or dihydrazide in formula (2) or in the section on other diamines below.

[0041] The polyamic acid derivative is a compound in which a part of the polyamic acid is replaced with another atom or atomic group to modify the properties, and it is preferable that the polyamic acid derivative has high solubility in a solvent used for the liquid crystal alignment agent. Specific examples of such polyamic acid derivatives include 1) polyimides in which all amino groups and carboxyl groups of the polyamic acid are subjected to a dehydration ring-closing reaction, 2) partial polyimides in which a part of the polyamic acid is subjected to a dehydration ring-closing reaction, 3) polyamic acid esters in which the carboxyl groups of the polyamic acid are converted into esters, 4) polyamic acid-polyamide copolymers obtained by replacing a part of the acid dianhydride contained in a tetracarboxylic dianhydride compound with an organic dicarboxylic acid and reacting the resulting mixture, and 5) polyamideimides in which a part or all of the polyamic acid-polyamide copolymer is subjected to a dehydration ring-closing reaction. Among these derivatives, for example, polyimides can be exemplified by those having a constitutional unit represented by the above formula (PI), and polyamic acid esters can be exemplified by those having a constitutional unit represented by the following formula (PAE). TIFF0007663449000032.tif3546 In the formula (PAE), X 1 is a tetravalent organic group, and X 2is a divalent organic group, and Y is independently an alkyl group. 1 , X 2 The preferred range and specific examples of X in formula (PAA) are 1 , X 2 For Y, a linear or branched alkyl group having 1 to 6 carbon atoms is preferable, and a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, or a tertiary butyl group is more preferable.

[0042] Polyamic acids can be obtained as reaction products by polymerization reaction of tetracarboxylic dianhydrides and diamines. For the explanation, preferred range and specific examples of tetracarboxylic dianhydrides, please refer to the description in the section on tetracarboxylic dianhydrides below. For the explanation, preferred range and specific examples of diamines, please refer to the description in the section on diamines below.

[0043] The tetracarboxylic dianhydrides and diamines used in the synthesis of the polyamic acid may each be one type or two or more types. The polyamic acid of the present invention can be obtained by using a compound represented by formula (1-1) or formula (1-2) as at least one of the tetracarboxylic dianhydrides, and further using a compound having a photoreactive structure that imparts liquid crystal alignment to the alignment film by photoreaction.

[0044] When the polyamic acid of the present invention is converted into a polyimide, which is a polyamic acid derivative, the polyimide can be obtained by imidizing the obtained polyamic acid solution together with an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride, which is a dehydrating agent, and a tertiary amine such as triethylamine, pyridine, or collidine, which is a dehydration ring-closing catalyst, at a temperature of 20 to 150° C. Alternatively, the polyamic acid can be precipitated from the obtained polyamic acid solution using a large amount of a poor solvent (an alcohol-based solvent such as methanol, ethanol, or isopropyl alcohol, or a glycol-based solvent), and the precipitated polyamic acid can be imidized in a solvent such as toluene or xylene together with the above-mentioned dehydrating agent and dehydration ring-closing catalyst at a temperature of 20 to 150° C. to obtain a polyimide.

[0045] 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-closing catalyst used is preferably 1.5 to 10 times the total molar amount of the tetracarboxylic dianhydride used in the synthesis of the polyamic acid. The degree of imidization can be controlled by adjusting the amount of the dehydrating agent and catalyst used in this imidization reaction, the reaction temperature, and the reaction time, and thus a partial polyimide in which only a part of the polyamic acid is imidized can be obtained. The obtained polyimide can be separated from the solvent used in the reaction and redissolved in another solvent to be used as a liquid crystal alignment agent, or it can be used as a liquid crystal alignment agent without being separated from the solvent.

[0046] The polyamic acid ester can be obtained by a synthesis method of reacting a polyamic acid with a hydroxyl group-containing compound, a halide, an epoxy group-containing compound, or the like, or by a synthesis method of reacting a tetracarboxylic acid diester or a tetracarboxylic acid diester dichloride derived from a tetracarboxylic acid dianhydride with a diamine. The tetracarboxylic acid diester derived from a tetracarboxylic acid dianhydride can be obtained, for example, by reacting the tetracarboxylic acid dianhydride with two equivalents of an alcohol to open the ring, and the tetracarboxylic acid diester dichloride can be obtained by reacting the tetracarboxylic acid diester with two equivalents of a chlorinating agent (e.g., thionyl chloride, etc.). The polyamic acid ester may have only an amic acid ester structure, or may be a partial ester in which the amic acid structure and the amic acid ester structure coexist. The polyamic acid ester of the present invention can be obtained by using a compound represented by formula (1-1) or formula (1-2) as at least one of the tetracarboxylic acid dianhydrides, and further using a compound having a photoreactive structure that imparts liquid crystal alignment to the alignment film by photoreaction.

[0047] The polyamic acid or its derivative of the present invention can be produced in the same manner as known polyamic acids or their derivatives used in the formation of polyimide films. The total amount of tetracarboxylic dianhydrides is preferably 0.9 to 1.1 moles per mole of the total amount of diamines.

[0048] The liquid crystal aligning agent of the present invention may contain only one of these polyamic acids, polyamic acid esters, and polyimides obtained by imidizing these, or may contain two or more of them.

[0049] The molecular weight of the polyamic acid or its derivative of the present invention is, in terms of polystyrene equivalent weight average molecular weight (Mw), preferably 5,000 to 500,000, more preferably 5,000 to 50,000. The molecular weight of the polyamic acid or its derivative can be determined by measurement using gel permeation chromatography (GPC).

[0050] The presence of the polyamic acid or its derivative of the present invention can be confirmed by analyzing the solid content obtained by precipitating the polyamic acid or its derivative with a large amount of poor solvent using IR (infrared spectroscopy) or NMR (nuclear magnetic resonance analysis).The monomer used can also be confirmed by analyzing an extract of the decomposition product of the polyamic acid or its derivative with an aqueous solution of a strong alkali such as KOH or NaOH using an organic solvent using GC (gas chromatography), HPLC (high performance liquid chromatography) or GC-MS (gas chromatography mass spectrometry).

[0051] <Other tetracarboxylic dianhydrides> The tetracarboxylic dianhydrides other than the compounds represented by formula (1-1) or formula (1-2) used as the raw material for the polymer of the present invention can be selected from known tetracarboxylic dianhydrides without any limitation.

[0052] Other examples of tetracarboxylic dianhydrides are given below. These tetracarboxylic dianhydrides may be converted into tetracarboxylic diesters or tetracarboxylic diester dichlorides and used as raw materials for polymers.

[0053] Such tetracarboxylic dianhydrides may belong to either an aromatic group (including a heteroaromatic ring system) in which a dicarboxylic anhydride is directly bonded to an aromatic ring, or an aliphatic group (including a heterocyclic ring system) in which a dicarboxylic anhydride is not directly bonded to an aromatic ring.

[0054] Examples of such tetracarboxylic dianhydrides include the compounds represented by the following formulae (AN-1) to (AN-9), (AN-11), (AN-12), (AN-15), (AN-10-1), (AN-10-2), and (AN-16-1) to (AN-16-15).

[0055] [Tetracarboxylic acid dianhydride represented by formula (AN-1)] TIFF0007663449000033.tif2877 In formula (AN-1), G 11 X is a single bond, an alkylene group having 1 to 12 carbon atoms, a 1,4-phenylene group, or a 1,4-cyclohexylene group. 11 are independently a single bond or -CH 2 -It is. G 12 are independently any of the following trivalent groups: TIFF0007663449000034.tif1131 G 12 When is >CH-, the hydrogen atom of >CH- may be replaced by a methyl group. 12 When is >N-, G 11 is a single bond and -CH 2 -, not X 11 cannot be a single bond. R 11 are independently a hydrogen atom or a methyl group.

[0056] Examples of the tetracarboxylic dianhydride represented by formula (AN-1) include the compounds represented by the following formulae (AN-1-1) to (AN-1-15). TIFF0007663449000035.tif140140 In formulas (AN-1-2) and (AN-1-14), each m is independently an integer of 1 to 12.

[0057] [Tetracarboxylic acid dianhydride represented by formula (AN-2)] TIFF0007663449000036.tif3631 In formula (AN-2), R 61 are independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a phenyl group.

[0058] Examples of the tetracarboxylic dianhydride represented by formula (AN-2) include the compounds represented by the following formulae (AN-2-1) to (AN-2-3). TIFF0007663449000037.tif38127

[0059] [Tetracarboxylic acid dianhydride represented by formula (AN-3)] TIFF0007663449000038.tif2874 In formula (AN-3), ring A 11 is a cyclohexane ring or a benzene ring.

[0060] Examples of the tetracarboxylic dianhydride represented by formula (AN-3) include compounds represented by the following formulae (AN-3-1) and (AN-3-2). TIFF0007663449000039.tif2877

[0061] [Tetracarboxylic acid dianhydride represented by formula (AN-4)] TIFF0007663449000040.tif2882 In formula (AN-4), G 13 is a single bond, -(CH 2 ) m -, -O-, -S-, -C(CH 3 ) 2 -, -SO 2 -, -CO-, -C(CF 3 ) 2 -, or a divalent group represented by the following formula (G13-1), where m is an integer of 1 to 12. 11 are each independently a cyclohexane ring or a benzene ring. 13 is ring A 11 It may be attached at any position of the TIFF0007663449000041.tif1872 In formula (G13-1), G 13a and G 13bare each independently a single bond, or a divalent group represented by -O-, -CONH-, or -NHCO-. The phenylene group is preferably a 1,4-phenylene group or a 1,3-phenylene group.

[0062] Examples of the tetracarboxylic dianhydride represented by formula (AN-4) include the compounds represented by the following formulae (AN-4-1) to (AN-4-31). TIFF0007663449000042.tif111143 TIFF0007663449000043.tif143138 In formula (AN-4-17), m is an integer from 1 to 12.

[0063] TIFF0007663449000044.tif61125 TIFF0007663449000045.tif64158

[0064] [Tetracarboxylic acid dianhydride represented by formula (AN-5)] TIFF0007663449000046.tif4174 In formula (AN-5), R 11 are independently a hydrogen atom or a methyl group. 11 Among them, R in the benzene ring 11 is attached to any of the substitutable positions of the benzene ring.

[0065] Examples of the tetracarboxylic dianhydride represented by formula (AN-5) include the compounds represented by the following formulae (AN-5-1) to (AN-5-3). TIFF0007663449000047.tif43118

[0066] [Tetracarboxylic acid dianhydride represented by formula (AN-6)] TIFF0007663449000048.tif2379 In formula (AN-6), X 11 are independently a single bond or -CH 2 - X 12 Ha-CH 2 -, -CH 2 CH 2 - or -CH=CH-. n is 1 or 2. When n is 2, two X 12 may be the same or different from each other.

[0067] Examples of the tetracarboxylic dianhydride represented by formula (AN-6) include the compounds represented by the following formulae (AN-6-1) to (AN-6-12). TIFF0007663449000049.tif115132

[0068] [Tetracarboxylic dianhydride represented by formula (AN-7)] TIFF0007663449000050.tif3174 In formula (AN-7), X 11 is a single bond or -CH 2 -It is.

[0069] Examples of the tetracarboxylic dianhydride represented by formula (AN-7) include the compounds represented by the following formulae (AN-7-1) and (AN-7-2). TIFF0007663449000051.tif3474

[0070] [Tetracarboxylic dianhydride represented by formula (AN-8)] TIFF0007663449000052.tif3974 In formula (AN-8), X 11 is a single bond or -CH 2 -It is. 12 is a hydrogen atom, a methyl group, an ethyl group, or a phenyl group. 12 is a cyclohexane ring or a cyclohexene ring.

[0071] Examples of the tetracarboxylic dianhydride represented by formula (AN-8) include the compounds represented by the following formulae (AN-8-1) and (AN-8-2). TIFF0007663449000053.tif4472

[0072] [Tetracarboxylic acid dianhydride represented by formula (AN-9)] TIFF0007663449000054.tif3174 In formula (AN-9), each r is independently 0 or 1.

[0073] Examples of the tetracarboxylic dianhydride represented by formula (AN-9) include the compounds represented by the following formulae (AN-9-1) to (AN-9-3). TIFF0007663449000055.tif34140

[0074] [Tetracarboxylic acid dianhydrides represented by formula (AN-10-1) and formula (AN-10-2)] TIFF0007663449000056.tif3474

[0075] [Tetracarboxylic dianhydride represented by formula (AN-11)] TIFF0007663449000057.tif2877 In formula (AN-11), ring A 11 are independently a cyclohexane ring or a benzene ring.

[0076] Examples of the tetracarboxylic dianhydride represented by formula (AN-11) include the compounds represented by the following formulae (AN-11-1) to (AN-11-3). TIFF0007663449000058.tif28133

[0077] [Tetracarboxylic dianhydride represented by formula (AN-12)] TIFF0007663449000059.tif3477 In formula (AN-12), ring A 11 are each independently a cyclohexane ring or a benzene ring.

[0078] Examples of the tetracarboxylic dianhydride represented by formula (AN-12) include the compounds represented by the following formulae (AN-12-1) to (AN-12-3). TIFF0007663449000060.tif36138

[0079] [Tetracarboxylic dianhydride represented by formula (AN-15)] TIFF0007663449000061.tif2377 In formula (AN-15), w is an integer of 1 to 10.

[0080] Examples of the tetracarboxylic dianhydride represented by formula (AN-15) include the compounds represented by the following formulae (AN-15-1) to (AN-15-3). TIFF0007663449000062.tif28146

[0081] [Tetracarboxylic acid dianhydrides represented by formulas (AN-16-1) to (AN-16-15)] Other tetracarboxylic dianhydrides include the compounds represented by the following formulae (AN-16-1) to (AN-16-15). TIFF0007663449000063.tif153137

[0082] Among the above tetracarboxylic dianhydrides, preferred materials for improving the properties of the liquid crystal alignment film are described below. When emphasis is placed on further improving the liquid crystal alignment, the compounds represented by formula (AN-1-2), formula (AN-4-17), formula (AN-4-21), or formula (AN-4-29) are more preferred, and in formula (AN-1-2), m is preferably 4 to 8, and in formula (AN-4-17), m is preferably 4 to 8.

[0083] When emphasis is placed on improving the transmittance of a liquid crystal display element, the compounds represented by formula (AN-1-1), (AN-1-2), (AN-2-1), (AN-3-1), (AN-4-17), (AN-4-30), (AN-5-1), (AN-7-2), (AN-10-1), (AN-16-3) or (AN-16-4) are preferred, and in formula (AN-1-2), m is preferably 4 or 8, and in formula (AN-4-17), m is preferably 4 to 8, and more preferably m is 8.

[0084] When emphasis is placed on improving the VHR of a liquid crystal display element, the compounds represented by formula (AN-1-1), (AN-1-2), (AN-3-1), (AN-4-17), (AN-4-30), (AN-7-2), (AN-10-1), (AN-16-3), (AN-16-4) or (AN-2-1) are preferred, and in formula (AN-1-2), m is preferably 4 or 8, and in formula (AN-4-17), m is preferably 4 or 8, and more preferably m is 8.

[0085] One effective method for preventing image sticking is to improve the relaxation speed of the residual charge (residual DC) in the liquid crystal alignment film by reducing the volume resistance of the liquid crystal alignment film. When this purpose is important, the compounds represented by formula (AN-1-13), formula (AN-3-2), formula (AN-4-21), formula (AN-4-29), or formula (AN-11-3) are preferred.

[0086] <Other diamines> Diamines other than the compounds represented by formula (2) or (3) used as raw materials for the polymer of the present invention can be selected from known diamines without any limitation.

[0087] Diamines can be divided into two types based on their structure. That is, when the skeleton connecting the two amino groups is viewed as the main chain, there are diamines that have groups branching from the main chain, i.e., side chain groups, and diamines that do not have side chain groups. In the following explanation, diamines that have such side chain groups may be referred to as side chain type diamines. And diamines that do not have such side chain groups may be referred to as non-side chain type diamines. The side chain groups are groups that have the effect of increasing the pretilt angle. By appropriately using the non-side chain type diamine and the side chain type diamine, it is possible to meet the pretilt angle required for each.

[0088] It is preferable to use the side chain diamines in combination to the extent that the characteristics of the present invention are not impaired. It is also preferable to selectively use the side chain diamines and the non-side chain diamines for the purpose of improving characteristics such as vertical alignment property for liquid crystal, VHR, and afterimage characteristics.

[0089] Known diamines having no side chains are shown in the following formulas (DI-1) to (DI-16). TIFF0007663449000064.tif126136 In the above formula (DI-1), G 20 is -CH 2 - or a group represented by formula (DI-1-a). 20 Ga-CH 2 -, when m -CH 2 At least one of - may be replaced by -NH- or -O-, and m -CH 2 At least one hydrogen atom of - may be substituted with a hydroxyl group or a methyl group. m is an integer of 1 to 12. When m in DI-1 is 2 or more, multiple G 20 may be the same or different from each other, provided that G 20When the formula is (DI-1-a), m is 1. TIFF0007663449000065.tif2136 In formula (DI-1-a), each v is independently an integer of 1 to 6.

[0090] In formula (DI-3), formula (DI-6) and formula (DI-7), G 21 are independently a single bond, -NH-, or -NCH 3 -, -O-, -S-, -SS-, -SO 2 -, -CO-, -COO-, -CONCH 3 -, -CONH-, -C(CH 3 ) 2 -, -C(CF 3 ) 2 -, -(CH 2 ) m -, -O-(CH 2 ) m -O-, -N(CH 3 )-(CH 2 ) k -N(CH 3 )-, -(OC 2 H 4 ) m -O-, -O-CH 2 -C(CF 3 ) 2 -CH 2 -O-, -O-CO-(CH 2 ) m -CO-O-, -CO-O-(CH 2 ) m -O-CO-, -(CH 2 ) m -NH-(CH 2 ) m -, -CO-(CH 2 ) k -NH-(CH 2 ) k -, -(NH-(CH 2 ) m ) k -NH-, -CO-C 3 H 6 -(NH-C 3 H 6 ) n-CO-, or -S-(CH 2 ) m -S-, m is independently an integer of 1 to 12, k is an integer of 1 to 5, and n is 1 or 2. In formula (DI-4), s is independently an integer of 0 to 2.

[0091] In formula (DI-5), G 33 is a single bond, -NH-, -NCH 3 -, -O-, -S-, -SS-, -SO 2 -, -CO-, -COO-, -CONCH 3 -, -CONH-, -C(CH 3 ) 2 -, -C(CF 3 ) 2 -, -(CH 2 ) m -, -O-(CH 2 ) m -O-, -N(CH 3 )-(CH 2 ) k -N(CH 3 )-, -(OC 2 H 4 ) m -O-, -O-CH 2 -C(CF 3 ) 2 -CH 2 -O-, -O-CO-(CH 2 ) m -CO-O-, -CO-O-(CH 2 ) m -O-CO-, -(CH 2 ) m -NH-(CH 2 ) m -, -CO-(CH 2 ) k -NH-(CH 2 ) k -, -(NH-(CH 2 ) m ) k -NH-, -CO-C 3 H 6 -(NH-C 3 H 6 ) n -CO-, or -S-(CH2 ) m -S-, -N(Boc)-(CH 2 ) e -N(Boc)-, -NH-(CH 2 ) e -N(Boc)-, -N(Boc)-(CH 2 ) e -, -(CH 2 ) m -N(Boc)-CONH-(CH 2 ) m -, -(CH 2 ) m -N(Boc)-(CH 2 ) m -, or a group represented by the following formula (DI-5-a) or the following formula (DI-5-b), where 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 a t-butoxycarbonyl group.

[0092] In formula (DI-6) and formula (DI-7), G 22 are independently a single bond, -O-, -S-, -CO-, -C(CH 3 ) 2 -, -C(CF 3 ) 2 -, or an alkylene group having 1 to 10 carbon atoms.

[0093] At least one hydrogen atom of the cyclohexane ring and the benzene ring in the formulae (DI-2) to (DI-7) may be substituted with a fluorine atom, a chlorine atom, an alkylene group having 1 to 3 carbon atoms, a -methoxy group, a hydroxyl group, a trifluoromethyl group, a carboxy group, a carbamoyl group, a phenylamino group, a phenyl group, or a benzyl group. In addition, in the formula (DI-4), at least one hydrogen atom of the cyclohexane ring and the benzene ring may be substituted with one selected from the group represented by any of the following formulae (DI-4-a) to (DI-4-i). In the formula (DI-5), G 33 When is a single bond, at least one hydrogen atom of the cyclohexane ring and the benzene ring is NHBoc or N(Boc). 2 may be substituted.

[0094] A group that is not fixed to a carbon atom that constitutes a ring indicates that the bonding position in the ring is arbitrary. The bonding position of an amino group to a cyclohexane ring or a benzene ring is G 21 , G 22 or G 33 The position may be any position except the bonding position of TIFF0007663449000066.tif38140 TIFF0007663449000067.tif43155 In formula (DI-4-a) and formula (DI-4-b), R 20 are independently a hydrogen atom or a methyl group. In formulae (DI-4-f) and (DI-4-g), m is each independently an integer of 0 to 12, and Boc is a t-butoxycarbonyl group.

[0095] TIFF0007663449000068.tif3897 In formula (DI-5-a), each q is independently an integer of 0 to 6. 44 is a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0096] TIFF0007663449000069.tif84130 In formula (DI-11), r is 0 or 1. In formulas (DI-8) to (DI-11), the bonding position of the amino group bonded to the ring is any position.

[0097] TIFF0007663449000070.tif127132 In 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 23each independently represents an alkylene group having 1 to 6 carbon atoms, a phenylene group, or a phenylene group substituted with an alkyl group; and w is an integer of 1 to 10. In formula (DI-13), R 23 each independently represents an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or -Cl; p each independently represents an integer of 0 to 3; and q each independently represents an integer of 0 to 4. In formula (DI-14), ring B is a monocyclic heteroaromatic group, and R 24 is a hydrogen atom, a fluorine atom, a chlorine atom, an alkyl group, an alkoxy group, an alkenyl group, or an alkynyl group having 1 to 6 carbon atoms, and q is independently an integer of 0 to 4. When q is 2 or more, multiple R 24 may be the same or different from each other. In formula (DI-15), ring C is a heterocyclic aromatic group or a heterocyclic aliphatic group. In 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. A group that is not fixedly bonded to a carbon atom constituting a ring indicates that the bonding position in the ring is arbitrary. In formulae (DI-13) to (DI-16), the bonding position of the amino group bonded to the ring is arbitrary.

[0098] Examples of the diamine represented by formula (DI-1) are shown in the following formulas (DI-1-1) to (DI-1-9). TIFF0007663449000071.tif87132 In formula (DI-1-7) and formula (DI-1-8), k is independently an integer of 1 to 3. In formula (DI-1-9), v is independently an integer of 1 to 6.

[0099] Examples of diamines represented by formulae (DI-2) to (DI-3) are shown in the following formulae (DI-2-1), (DI-2-2), and (DI-3-1) to (DI-3-3). TIFF0007663449000072.tif49135

[0100] Examples of the diamine represented by formula (DI-4) are shown in the following formulas (DI-4-1) to (DI-4-27). TIFF0007663449000073.tif61125 TIFF0007663449000074.tif59127 TIFF0007663449000075.tif44132 TIFF0007663449000076.tif44132 TIFF0007663449000077.tif2682 TIFF0007663449000078.tif41160 In formulas (DI-4-20) and (DI-4-21), each m is independently an integer of 1 to 12. TIFF0007663449000079.tif84143

[0101] Examples of the diamine represented by formula (DI-5) are shown in the following formulas (DI-5-1) to (DI-5-50). TIFF0007663449000080.tif77150 In formula (DI-5-1), m is an integer of 1 to 12.

[0102] TIFF0007663449000081.tif66127 In formula (DI-5-12) and formula (DI-5-13), each m is independently an integer of 1 to 12.

[0103] TIFF0007663449000082.tif94132 In formula (DI-5-16), v is an integer of 1 to 6.

[0104] TIFF0007663449000083.tif97155 In formula (DI-5-30), k is an integer of 1 to 5.

[0105] TIFF0007663449000084.tif130143 In Formulas (DI-5-35) to (DI-5-37) and (DI-5-39), m is each independently an integer of 1 to 12; in Formulas (DI-5-38) and (DI-5-39), k is each independently an integer of 1 to 5; and in Formula (DI-5-40), n is an integer of 1 or 2.

[0106] TIFF0007663449000085.tif54138 In formulas (DI-5-42) to (DI-5-44), e is independently an integer of 2 to 10, and in formula (DI-5-45), R 43 is a hydrogen atom, a (t-butoxycarbonyl)amino group, or a bis(t-butoxycarbonyl)amino group. In Formulae (DI-5-42) to (DI-5-44), Boc is a t-butoxycarbonyl group.

[0107] TIFF0007663449000086.tif44112 TIFF0007663449000087.tif2672 TIFF0007663449000088.tif35150

[0108] Examples of the diamine represented by formula (DI-6) are shown in the following formulas (DI-6-1) to (DI-6-7). TIFF0007663449000089.tif82143

[0109] Examples of the diamine represented by formula (DI-7) are shown in the following formulas (DI-7-1) to (DI-7-11). TIFF0007663449000090.tif94102 In formula (DI-7-3) and formula (DI-7-4), m is each independently an integer of 1 to 12, and n is independently 1 or 2.

[0110] TIFF0007663449000091.tif9371 TIFF0007663449000092.tif3979

[0111] Examples of the diamine represented by formula (DI-8) are shown in the following formulas (DI-8-1) to (DI-8-4). TIFF0007663449000093.tif31140

[0112] Examples of the diamine represented by formula (DI-9) are shown in the following formulas (DI-9-1) to (DI-9-3). TIFF0007663449000094.tif34143

[0113] Examples of diamines represented by formula (DI-10) are shown in the following formulas (DI-10-1) and (DI-10-2). TIFF0007663449000095.tif3189

[0114] Examples of the diamine represented by formula (DI-11) are shown in the following formulas (DI-11-1) to (DI-11-3). TIFF0007663449000096.tif23140

[0115] An example of the diamine represented by formula (DI-12) is shown in the following formula (DI-12-1). TIFF0007663449000097.tif2866

[0116] Examples of diamines represented by formula (DI-13) are shown in the following formulas (DI-13-1) to (DI-13-13). TIFF0007663449000098.tif23130 TIFF0007663449000099.tif66132 TIFF0007663449000100.tif66130

[0117] Examples of diamines represented by formula (DI-14) are shown in the following formulas (DI-14-1) to (DI-14-9). TIFF0007663449000101.tif74117

[0118] Examples of diamines represented by formula (DI-15) are shown in the following formulas (DI-15-1) to (DI-5-12). TIFF0007663449000102.tif61150 TIFF0007663449000103.tif61153

[0119] An example of the diamine represented by formula (DI-16) is shown in the following formula (DI-16-1). TIFF0007663449000104.tif2659

[0120] Next, the dihydrazide used as the raw material for the polymer of the present invention will be described. Known dihydrazides having no side chains include compounds represented by any of the following formulas (DIH-1) to (DIH-3). TIFF0007663449000105.tif56102 In formula (DIH-1), G 25 represents a single bond, an alkylene group having 1 to 20 carbon atoms, -CO-, -O-, -S-, -SO 2 -, -C(CH 3 ) 2 - or -C(CF 3 ) 2 -It is. In formula (DIH-2), ring D is a cyclohexane ring, a benzene ring or a naphthalene ring, and at least one hydrogen atom of this group may be substituted with a methyl group, an ethyl group, or a phenyl group. In formula (DIH-3), each ring E is independently a cyclohexane ring or a benzene ring, and at least one hydrogen atom of this group may be substituted with a methyl group, an ethyl group, or a phenyl group. A plurality of rings E may be the same 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(CH 3 ) 2 - or -C(CF 3 ) 2 -It is. In formula (DIH-2) and formula (DIH-3), the hydrazide group may be bonded to the ring at any position.

[0121] Examples of the compounds represented by any one of formulas (DIH-1) to (DIH-3) are shown in the following formulas (DIH-1-1), (DIH-1-2), (DIH-2-1) to (DIH-2-3), and (DIH-3-1) to (DIH-3-6). TIFF0007663449000106.tif2689 In formula (DIH-1-2), m is an integer of 1 to 12.

[0122] TIFF0007663449000107.tif31148 TIFF0007663449000108.tif84137

[0123] Diamines suitable for increasing the pretilt angle will be described. The compound of the present invention can be suitably used as a liquid crystal aligning agent for use in a horizontal electric field type liquid crystal display element, but it is also possible to increase the pretilt angle by using it in combination with the following diamines. Diamines having a side chain group suitable for increasing the pretilt angle include diamines represented by any of formulas (DI-31) to (DI-35) and formulas (DI-36-1) to (DI-36-8). TIFF0007663449000109.tif3679

[0124] In formula (DI-31), G 26 is a single bond, -O-, -COO-, -OCO-, -CO-, -CONH-, -CH 2 O-, -OCH 2 -, -CF 2 O-, -OCF 2 - or -(CH 2 ) ma -, and ma is an integer from 1 to 12. 26 Preferred examples of the group include a single bond, -O-, -COO-, -OCO-, and -CH 2 O-, and an alkylene group having 1 to 3 carbon atoms. Particularly preferred examples are a single bond, -O-, -COO-, -OCO-, and -CH 2 O-, -CH 2 - and -CH 2 CH 2 -It is. 25 is an alkyl group having 3 to 30 carbon atoms, a phenyl group, a group having a steroid skeleton, or a group represented by the following formula (DI-31-a). In this alkyl group, at least one hydrogen atom may be substituted with a fluorine atom, and at least one -CH 2- may be substituted with -O-, -CH=CH- or -C≡C-. The hydrogen atom of this phenyl group may be substituted with a fluorine atom, a methyl group, a methoxy group, a fluoromethyloxy group, a difluoromethyloxy group, a trifluoromethyloxy group, an alkyl group having 3 to 30 carbon atoms or an alkoxy group having 3 to 30 carbon atoms. The bonding position of the amino group bonded to the benzene ring may be any position on the ring, but the bonding position is preferably the meta position or para position. That is, the group "R 25 -G 26 When the bonding position of "-" is regarded as the 1st position, the two bonding positions are preferably the 3rd and 5th positions, or the 2nd and 5th positions.

[0125] TIFF0007663449000110.tif13135 In formula (DI-31-a), G 27 , G 28 and G 29 are bonding groups, each of which is independently a single bond or an alkylene group having 1 to 12 carbon atoms, and one or more -CH 2 - may be substituted with -O-, -COO-, -OCO-, -CONH-, or -CH=CH-. 21 , ring B 22 , ring B 23 and ring B 24 are each independently a 1,4-phenylene group, a 1,4-cyclohexylene group, a 1,3-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; 21 , ring B 22 , ring B 23 and ring B 24 In the formula, at least one hydrogen atom may be substituted with a fluorine atom or a methyl group, s, t, and u are each independently an integer of 0 to 2, the sum of which is 1 to 5, and when s, t, or u is 2, the two bonding groups in each parentheses may be the same or different, and the two rings may be the same or different.26 is a hydrogen atom, a fluorine atom, a hydroxyl group, an alkyl group having 1 to 30 carbon atoms, a fluorine-substituted alkyl group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, a cyano group, a fluoromethyloxy group, a difluoromethyloxy group, or a trifluoromethyloxy group, and at least one of the -CH 2 - may be substituted with a divalent group represented by the following formula (DI-31-b). TIFF0007663449000111.tif2182 In formula (DI-31-b), R 27 and R 28 are each independently an alkyl group having 1 to 3 carbon atoms, and v is an integer of 1 to 6. 26 Preferred examples of the group include an alkyl group having 1 to 30 carbon atoms and an alkoxy group having 1 to 30 carbon atoms.

[0126] TIFF0007663449000112.tif87114 In formula (DI-32) and formula (DI-33), G 30 are independently a single bond, -CO- or -CH 2 - and R 29 are independently a hydrogen atom or a methyl group, and R 30 is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an alkenyl group having 2 to 20 carbon atoms. At least one hydrogen atom of the benzene ring in formula (DI-33) may be substituted with an alkyl group having 1 to 20 carbon atoms or a phenyl group. A group that is not fixedly bonded to any carbon atom constituting the ring indicates that the bonding position in the ring is arbitrary. Two groups "-phenylene-G" in formula (DI-32) 30 It is preferred that one of the -O- groups is bonded to the 3-position of the steroid nucleus, and the other is bonded to the 6-position of the steroid nucleus. 30The bonding position of -O-" to the benzene ring is preferably meta-position or para-position relative to the bonding position of the steroid nucleus. In formulae (DI-32) and (DI-33), the amino group bonded to the benzene ring indicates that the bonding position in the ring is arbitrary.

[0127] TIFF0007663449000113.tif77115 In formula (DI-34) and formula (DI-35), G 31 are independently -O- or an alkylene group having 1 to 6 carbon atoms; G 32 R is a single bond or an alkylene group having 1 to 3 carbon atoms. 31 is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and at least one -CH 2 - may be replaced by -O-, -CH=CH- or -C≡C-. 32 is an alkyl group having 6 to 22 carbon atoms, and R 33 is a hydrogen atom or an alkyl group having 1 to 22 carbon atoms. 25 is a 1,4-phenylene group or a 1,4-cyclohexylene group, and r is 0 or 1. The amino group bonded to the benzene ring indicates that the bond position on the ring is arbitrary, but independently, G 31 It is preferably in the meta or para position relative to the bonding position of

[0128] Examples of the compound represented by formula (DI-31) are shown in the following formulae (DI-31-1) to (DI-31-55). TIFF0007663449000114.tif163143

[0129] In formulas (DI-31-1) to (DI-31-11), R 34 R are each independently an alkyl group having 1 to 30 carbon atoms or an alkoxy group having 1 to 30 carbon atoms, and preferably an alkyl group having 5 to 25 carbon atoms or an alkoxy group having 5 to 25 carbon atoms. 35each independently represents an alkyl group having 1 to 30 carbon atoms or an alkoxy group having 1 to 30 carbon atoms, and preferably an alkyl group having 3 to 25 carbon atoms or an alkoxy group having 3 to 25 carbon atoms. TIFF0007663449000115.tif77119

[0130] In formulas (DI-31-12) to (DI-31-17), R 36 R is independently an alkyl group having 4 to 30 carbon atoms, and preferably an alkyl group having 6 to 25 carbon atoms. 37 are each independently an alkyl group having 6 to 30 carbon atoms, and preferably an alkyl group having 8 to 25 carbon atoms. TIFF0007663449000116.tif76134 TIFF0007663449000117.tif84143 TIFF0007663449000118.tif77148 TIFF0007663449000119.tif54122 TIFF0007663449000120.tif107140

[0131] In formulas (DI-31-18) to (DI-31-43), R 38 R are each independently an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms, and preferably an alkyl group having 3 to 20 carbon atoms or an alkoxy group having 3 to 20 carbon atoms. 39 are each independently a hydrogen atom, a fluorine atom, an alkyl group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, a cyano group, a fluoromethyloxy group, a difluoromethyloxy group, or a trifluoromethyloxy group, and are preferably an alkyl group having 3 to 25 carbon atoms, or an alkoxy group having 3 to 25 carbon atoms. 33 is an alkylene group having 1 to 20 carbon atoms.

[0132] TIFF0007663449000121.tif54150 TIFF0007663449000122.tif107150 TIFF0007663449000123.tif50134 TIFF0007663449000124.tif81131

[0133] Examples of the compound represented by formula (DI-32) are shown in the following formulas (DI-32-1) to (DI-32-4). TIFF0007663449000125.tif132150

[0134] Examples of the compound represented by formula (DI-33) are shown in the following formulas (DI-33-1) to (DI-33-8). TIFF0007663449000126.tif97150 TIFF0007663449000127.tif101149

[0135] Examples of the compound represented by formula (DI-34) are shown in the following formulas (DI-34-1) to (DI-34-12). TIFF0007663449000128.tif94148 TIFF0007663449000129.tif97148 TIFF0007663449000130.tif69148 TIFF0007663449000131.tif99148 In formulas (DI-34-1) to (DI-34-12), R 40 are each independently a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R 41 each independently represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.

[0136] Examples of the compound represented by formula (DI-35) are shown in the following formulae (DI-35-1) to (DI-35-3). TIFF0007663449000132.tif66125 In formulas (DI-35-1) to (DI-35-3), R 37 are each independently an alkyl group having 6 to 30 carbon atoms, and R 41 each independently represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.

[0137] The compounds represented by formulae (DI-36-1) to (DI-36-8) are shown below. TIFF0007663449000133.tif130153 In formulas (DI-36-1) to (DI-36-8), R 42 are each independently an alkyl group having 3 to 30 carbon atoms.

[0138] Among the above diamines, preferred materials for improving the properties of the liquid crystal alignment film described below will be described. When emphasis is placed on improving the liquid crystal alignment, it is preferable to use a compound represented by formula (DI-1-3), formula (DI-5-1), formula (DI-5-5), formula (DI-5-9), formula (DI-5-12), formula (DI-5-13), formula (DI-5-29), formula (DI-6-7), formula (DI-7-3), or formula (DI-11-2). In formula (DI-5-1), m is preferably 2 to 8, more preferably m is 4 to 8. In formula (DI-5-12), m is preferably 2 to 6, more preferably m is 5. In formula (DI-5-13), m is preferably 1 or 2, more preferably m is 1.

[0139] When emphasis is placed on improving the transmittance, it is preferable to use a diamine represented by formula (DI-1-3), formula (DI-2-1), formula (DI-5-1), formula (DI-5-5), formula (DI-5-24), or formula (DI-7-3), and more preferably a compound represented by formula (DI-2-1). In formula (DI-5-1), m is preferably 2 to 8, and more preferably m is 8. In formula (DI-7-3), m is preferably 2 or 3, n is preferably 1 or 2, and more preferably m is 3, n is preferably 1.

[0140] When it is important to improve the VHR of the liquid crystal display element, it is preferable to use a compound represented by formula (DI-2-1), formula (DI-4-1), formula (DI-4-2), formula (DI-4-10), formula (DI-4-15), formula (DI-4-22), formula (DI-5-1), formula (DI-5-28), formula (DI-5-30), or formula (DI-13-1), and more preferable is a diamine represented by formula (DI-2-1), formula (DI-5-1), or formula (DI-13-1). In formula (DI-5-1), m=1 is preferable. In formula (DI-5-30), k=2 is preferable.

[0141] One of the effective methods for preventing image sticking is to improve the relaxation speed of the residual charge (residual DC) in the liquid crystal alignment film by reducing the volume resistance of the liquid crystal alignment film. When this purpose is important, it is preferable to use a compound represented by formula (DI-4-1), formula (DI-4-2), formula (DI-4-10), formula (DI-4-15), formula (DI-5-1), formula (DI-5-12), formula (DI-5-13), formula (DI-5-28), formula (DI-4-20), formula (DI-4-21), formula (DI-7-12), or formula (DI-16-1), and more preferable to use a compound represented by formula (DI-4-1), formula (DI-5-1), or formula (DI-5-13). In formula (DI-5-1), m=2 to 8 is preferable, and m=4 to 8 is more preferable. In formula (DI-5-12), m is preferably 2 to 6, and more preferably m is 5. In formula (DI-5-13), m is preferably 1 or 2, and more preferably m is 1. In formula (DI-7-12), m is preferably 3 or 4, and more preferably m is 4.

[0142] In the raw material composition used as the raw material of the polymer of the present invention, a part of the diamines may be replaced with at least one selected from the group consisting of monoamines and monohydrazides. The ratio of the at least one selected from the group consisting of monoamines and monohydrazides to the diamines is preferably in the range of 40 mol% or less. Such a replacement can cause the termination of the polymerization reaction when producing polyamic acid, and can suppress the further progress of the polymerization reaction. For this reason, such a replacement can easily control the molecular weight of the resulting polymer (polyamic acid or its derivative), and can improve the coating properties of the liquid crystal alignment agent, for example, without impairing the effects of the present invention. The diamines that may be replaced with monoamines or monohydrazides may be one type or two or more types, 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, para-aminophenyltrimethoxysilane, and 3-aminopropyltriethoxysilane.

[0143] When the polymer of the present invention is a polyamic acid or its derivative, the raw material composition may further contain a monoisocyanate compound as a monomer. By including a monoisocyanate compound in the monomer, the terminal of the obtained polyamic acid or its derivative is modified, and the molecular weight is adjusted. By using this terminal-modified polyamic acid or its derivative, for example, the coating properties of the liquid crystal alignment agent can be improved without impairing the effect of the present invention. From the above viewpoint, it is preferable that the content of the monoisocyanate compound in the monomer is 1 to 10 mol% with respect to the total amount of the diamine and tetracarboxylic dianhydride in the monomer. Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.

[0144] The liquid crystal alignment agent of the present invention may be composed of one type of the polymer of the present invention, or may be a mixture of the polymer of the present invention and a polymer other than the present invention. In this specification, a liquid crystal alignment agent composed of one type of the polymer may be referred to as a single-layer type liquid crystal alignment agent. A liquid crystal alignment agent in which two or more types of the polymers are mixed may be referred to as a blend type liquid crystal alignment agent. A blend type liquid crystal alignment agent is used particularly when VHR reliability and other electrical properties are important.

[0145] As the polymer other than the present invention used in the blend type liquid crystal alignment agent, one or more of polyamic acid and polyamic acid derivatives are preferable. As the polymer other than the present invention, the above description of the polymer of the present invention can be referred to for polyamic acid and polyamic acid derivatives, except that the raw material composition does not simultaneously contain a compound having a photoreactive structure and a compound represented by formula (1-1) or formula (1-2).

[0146] When using a two-component polymer, for example, one embodiment is to select a polymer having excellent performance in liquid crystal alignment ability as one component, and a polymer having excellent performance in improving the electrical characteristics of a liquid crystal display element as the other component, which is suitable for obtaining an alignment agent with a good balance between liquid crystal alignment ability and electrical characteristics.

[0147] In this case, by controlling the structure and molecular weight of each polymer, the liquid crystal alignment agent in which these polymers are dissolved in a solvent is applied to a substrate as described below, and in the process of forming a thin film by pre-drying, the polymer having excellent performance in liquid crystal alignment ability can be segregated in the upper layer of the thin film, and the polymer having excellent performance in improving the electrical properties of the liquid crystal display element can be segregated in the lower layer of the thin film. For this, the phenomenon in which a polymer with a small surface energy is separated into the upper layer and a polymer with a large surface energy is separated into the lower layer in the mixed polymers can be applied. Such layer separation can be confirmed by checking that the surface energy of the formed liquid crystal alignment film is the same as or close to the surface energy of a film formed by a liquid crystal alignment agent containing only the polymer intended to be segregated in the upper layer.

[0148] Another method for realizing phase separation is to reduce the molecular weight of the polymer to be segregated to the upper layer.

[0149] In the case of a liquid crystal alignment agent consisting of a mixture of polymers, layer separation can be achieved by using polyimide as the polymer to be segregated in the upper layer.

[0150] The compound represented by formula (1-1) or formula (1-2) may be used as a raw material for the polymer that segregates in the upper layer of the thin film, or may be used as a raw material for the polymer that segregates in the lower layer of the thin film, or may be used as a raw material for both polymers, but is more preferably used as a raw material for the polymer that segregates in the upper layer of the thin film.

[0151] The compound represented by formula (2) or formula (3) may be used as a raw material for the polymer that segregates in the upper layer of the thin film, or may be used as a raw material for the polymer that segregates in the lower layer of the thin film, or may be used as a raw material for both polymers, but is more preferably used as a raw material for the polymer that segregates in the upper layer of the thin film.

[0152] The tetracarboxylic acid dianhydride other than the compound represented by formula (1-1) or formula (1-2) used for synthesizing the polyamic acid or its derivative segregated in the upper layer of the thin film and the polyamic acid or its derivative segregated in the lower layer of the thin film can be selected without limitation from the known tetracarboxylic acid dianhydrides exemplified above.

[0153] The tetracarboxylic dianhydride used to synthesize the polyamic acid or its derivative segregated in the upper layer of the thin film is preferably a compound represented by formula (AN-1-1), (AN-1-2), (AN-2-1), (AN-3-1), (AN-4-5), (AN-4-17), or (AN-4-21), more preferably formula (AN-4-17) or (AN-4-21). In formula (AN-4-17), m is preferably 4 to 8.

[0154] The tetracarboxylic dianhydride used to synthesize the polyamic acid or its derivative that segregates in the lower layer of the thin film is preferably a compound represented by formula (AN-1-1), formula (AN-1-13), formula (AN-2-1), formula (AN-3-2), or formula (AN-4-21), more preferably a compound represented by formula (AN-1-1), formula (AN-2-1), or formula (AN-3-2).

[0155] The tetracarboxylic acid dianhydride used to synthesize the polyamic acid or its derivative that segregates in the lower layer of the thin film preferably contains 10 mol % or more, and more preferably 30 mol % or more, of an aromatic tetracarboxylic acid dianhydride based on the total amount of the tetracarboxylic acid dianhydride.

[0156] Diamines other than the compound represented by formula (2) used for synthesizing the polyamic acid or its derivative segregated in the upper layer of the thin film and the polyamic acid or its derivative segregated in the lower layer of the thin film can be selected without limitation from the known diamines exemplified above.

[0157] As the diamines used to synthesize the polyamic acid or its derivatives segregated in the upper layer of the thin film, it is preferable to use a compound represented by formula (DI-4-1), formula (DI-4-13), formula (DI-4-15), formula (DI-5-1), formula (DI-7-3), or formula (DI-13-1). Among them, it is more preferable to use a compound represented by formula (DI-4-13), formula (DI-4-15), formula (DI-5-1), or formula (DI-13-1). In formula (DI-5-1), m=4 to 8 is preferable. In formula (DI-7-3), m=3, n=1 is preferable.

[0158] As diamines used to synthesize polyamic acid or its derivatives that segregate in the lower layer of the thin film, compounds represented by formula (DI-4-1), formula (DI-4-2), formula (DI-4-10), formula (DI-4-18), formula (DI-4-19), formula (DI-5-1), formula (DI-5-9), formula (DI-5-28), formula (DI-5-30), formula (DI-13-1), or formula (DIH-1-2) are preferred. In formula (DI-5-1), compounds in which m=1 or 2 are preferred, and in formula (DI-5-30), compounds in which k=2 are preferred. Among these, compounds represented by formula (DI-4-1), formula (DI-4-18), formula (DI-4-19), formula (DI-5-9), formula (DI-13-1), or formula (DIH-1-2) are more preferred.

[0159] The diamines used to synthesize the polyamic acid or its derivatives that segregate in the lower layer of the thin film preferably contain at least one selected from the group consisting of aromatic diamines and aromatic dihydrazides in an amount of 30 mol % or more, and more preferably 50 mol % or more, based on the total amount of the diamines.

[0160] The ratio of the polyamic acid or its derivative segregated in the upper layer of the thin film to the total amount of the polyamic acid or its derivative segregated in the upper layer of the thin film and the polyamic acid or its derivative segregated in the lower layer of the thin film is preferably 5% by weight to 60% by weight, and more preferably 20% by weight to 50% by weight.

[0161] The polyamic acid or derivative thereof of the present invention may be a block polymer including a first polymer chain and a second polymer chain having a structure different from that of the first polymer chain. The block polymer may further include another polymer chain having a structure different from that of the first polymer chain and the second polymer chain. For example, a block polymer of a polyamic acid may be prepared by mixing a solution of a specific polyamic acid (PAA1) represented by the formula (PAA) and a mixture of polyamic acid (PAA1) and X 1 and X 2 The block polymer of polyamic acid (PAA1) can be formed by mixing and heating solutions of polyamic acid (PAA2) with different combinations of (PAA1) and (PAA2). n1 and (PAA2) n2 (PAA1) n1 and (PAA2) n2 In the block polymer, n1 and n2 are each independently an integer of 1 or more, and preferably each independently an integer of 2 or more. In the block polymer, the polymer chains using the compounds represented by formula (1-1) or formula (1-2) and formula (2) or formula (3) in the raw material composition may be any one, two or more, or all of the polymer chains.

[0162] Here, the polyamic acid block polymer may be synthesized by mixing two or more kinds of polyamic acids produced individually and then heating them, or by synthesizing two or more kinds of polyamic acids in the same reaction vessel and then heating them, such as by synthesizing a first kind of polyamic acid and then adding the raw material of a second kind of polyamic acid to the same reaction vessel.

[0163] In the case of forming a block polymer, in the raw material composition used as the raw material of the polymer of the present invention, the compound represented by formula (1-1) or formula (1-2) is preferably 10 mol % or more, more preferably 20 mol % or more, based on the total amount of acid dianhydrides used as raw materials. The compound represented by formula (2) or formula (3) is preferably 10 mol % or more, more preferably 20 mol % or more, based on the total amount of diamines used as raw materials.

[0164] In addition, the liquid crystal aligning agent of the present invention may further contain a solvent from the viewpoint of adjusting the coating property of the liquid crystal aligning agent and the concentration of the polyamic acid or its derivative. The solvent can be applied without any particular limitation as long as it has the ability to dissolve the polymer component. The solvent includes a wide range of solvents that are commonly used in the manufacturing process and applications of polymer components such as polyamic acid and soluble polyimide, and can be appropriately selected depending on the purpose of use. The solvent may be one type or a mixed solvent of two or more types.

[0165] Examples of the solvent include a solvent that is compatible with the polyamic acid or its derivatives, and other solvents for the purpose of improving the coating properties.

[0166] Examples of aprotic polar organic solvents that are compatible with polyamic acid or its derivatives include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylimidazolidinone, N-methylcaprolactam, N-methylpropionamide, N,N-dimethylacetamide, dimethylsulfoxide, N,N-dimethylformamide, N,N-diethylformamide, diethylacetamide, N,N-dimethylisobutylamide, γ-butyrolactone, and γ-valerolactone. Among these, N-methyl-2-pyrrolidone, dimethylimidazolidinone, γ-butyrolactone, and γ-valerolactone are preferred.

[0167] Examples of other solvents for improving coating properties include ethylene glycol monoalkyl ethers such as ethylene glycol monobutyl ether and ethylene glycol monotertiary butyl ether, diethylene glycol monoalkyl ethers such as diethylene glycol monoethyl ether, and diethylene glycol dialkyl ethers such as diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, and diethylene glycol butyl methyl ether. In addition, 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. In addition, dialkyl malonates such as diethyl malonate, alkyl lactates, diisobutyl ketone, diacetone alcohol, 3-methyl-3-methoxybutanol, 4-methyl-2-pentanol, diisobutyl carbinol, tetralin, and isophorone.

[0168] Of these, diisobutyl ketone, 4-methyl-2-pentanol, diisobutyl carbinol, ethylene glycol monobutyl ether, ethylene glycol monotertiary 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.

[0169] The solid content concentration in the liquid crystal aligning agent of the present invention is not particularly limited, and an optimal value may be selected according to the various coating methods described below. In general, in order to suppress unevenness and pinholes during coating, the solid content is preferably 0.1 to 30% by weight, more preferably 1 to 10% by weight, based on the weight of the varnish.

[0170] The preferred range of the viscosity of the liquid crystal alignment agent of the present invention varies depending on the application method, the concentration of the polyamic acid or its derivative, the type of polyamic acid or its derivative used, and the type and ratio of the solvent. For example, in the case of application by a printer, the viscosity is 5 to 100 mPa·s (more preferably 10 to 80 mPa·s). If the viscosity is 5 mPa·s or more, a sufficient film thickness is easily obtained, and if the viscosity is 100 mPa·s or less, printing unevenness is easily suppressed. In the case of application by spin coating, the viscosity is suitable to be 5 to 200 mPa·s (more preferably 10 to 100 mPa·s). In the case of application by an inkjet coater, the viscosity is suitable to be 5 to 50 mPa·s (more preferably 5 to 20 mPa·s). The viscosity of the liquid crystal alignment agent is measured by a rotational viscosity measurement method, for example, using a rotational viscometer (TVE-20L type manufactured by Toki Sangyo Co., Ltd.) (measurement temperature: 25°C).

[0171] The liquid crystal alignment agent of the present invention may further contain various additives. Various additives can be selected and used according to the respective purposes in order to improve various properties of the alignment film. Examples are shown below.

[0172] <Alkenyl-substituted nadimide compounds> For example, the liquid crystal alignment agent of the present invention may further contain an alkenyl-substituted nadiimide compound for the purpose of stabilizing the electrical properties of the liquid crystal display element for a long period of time. The alkenyl-substituted nadiimide compound may be used alone or in combination of two or more. For the above purpose, the content of the alkenyl-substituted nadiimide compound is preferably 1 to 50% by weight, more preferably 1 to 30% by weight, and even more preferably 1 to 20% by weight, based on the polyamic acid or its derivative. The alkenyl-substituted nadiimide compound is preferably a compound that can be dissolved in a solvent that dissolves the polyamic acid or its derivative used in the present invention. Preferred alkenyl-substituted nadiimide compounds include the alkenyl-substituted nadiimide compounds disclosed in JP-A-2008-096979, JP-A-2009-109987, and JP-A-2013-242526. Particularly preferred alkenyl-substituted nadimide compounds include bis{4-(arylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide)phenyl}methane, N,N'-m-xylylene-bis(arylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide), or N,N'-hexamethylene-bis(arylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide).

[0173] <Compounds having radically polymerizable unsaturated double bonds> For example, the liquid crystal alignment 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 type of compound or two or more types of compounds. The compound having a radical polymerizable unsaturated double bond does not include an alkenyl-substituted nadiimide compound. Preferred compounds having a radical polymerizable unsaturated double bond include N,N'-methylenebisacrylamide, N,N'-dihydroxyethylene-bisacrylamide, ethylenebisacrylate, 4,4'-methylenebis(N,N-dihydroxyethyleneacrylateaniline), triallyl cyanurate, and other compounds having a radical polymerizable unsaturated double bond disclosed in JP 2009-109987 A, JP 2013-242526 A, WO 2014 / 119682, and WO 2015 / 152014. For the above-mentioned purposes, the content of the compound having a radically polymerizable unsaturated double bond is preferably 1 to 50% by weight, and more preferably 1 to 30% by weight, based on the polyamic acid or its derivative.

[0174] <Oxazine compounds> For example, the liquid crystal aligning agent of the present invention may further contain an oxazine compound for the purpose of stabilizing the electrical properties of a liquid crystal display element for a long period of time. The oxazine compound may be one type of compound or two or more types of 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 even more preferably 1 to 20% by weight, based on the polyamic acid or its derivative.

[0175] The oxazine compound is preferably soluble in the solvent that dissolves polyamic acid or its derivative, and has ring-opening polymerizability.Preferred oxazine compounds include the oxazine compounds represented by formula (OX-3-1), formula (OX-3-9), and formula (OX-3-10), and the oxazine compounds disclosed in JP-A-2007-286597 and JP-A-2013-242526. TIFF0007663449000134.tif72147

[0176] <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 a 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 type of compound or two or more types of compounds. For the above purpose, the content of the oxazoline compound is preferably 0.1 to 50% by weight, more preferably 1 to 40% by weight, and even more preferably 1 to 20% by weight, based on the polyamic acid or its derivative. Preferred oxazoline compounds include the oxazoline compounds disclosed in JP-A-2010-054872 and JP-A-2013-242526. More preferably, 1,3-bis(4,5-dihydro-2-oxazolyl)benzene is used.

[0177] <Epoxy compounds> 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 a liquid crystal display element for a long period of time, improving the hardness of the film, or improving the adhesion to a sealant. The epoxy compound may be one type of compound or two or more types of compounds. For the above purposes, the content of the epoxy compound is preferably 0.1 to 50% by weight, more preferably 1 to 20% by weight, and even more preferably 1 to 10% by weight, based on the polyamic acid or its derivative.

[0178] 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 a sealant, a compound having two or more epoxy rings in the molecule is preferred, and a compound having three or four epoxy rings is more preferred.

[0179] Examples of the epoxy compound include the epoxy compounds disclosed in JP 2009-175715 A, JP 2013-242526 A, JP 2016-170409 A, and WO 2017 / 217413. Preferred epoxy compounds include N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, (3,3',4,4'-diepoxy)bicyclohexyl, 1,4-butanediol glycidyl ether, tris(2,3-epoxypropyl) isocyanurate, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, or N,N,N',N'-tetraglycidyl-m-xylylenediamine. More preferred are 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane. In addition to the above, an oligomer or polymer having an epoxy ring can be added. As the oligomer or polymer having an epoxy ring, the oligomer or polymer disclosed in JP-A-2013-242526 can be used.

[0180] <Silane compounds> 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 further preferably 0.5 to 10% by weight, based on the polyamic acid or its derivative.

[0181] As the silane compound, silane coupling agents disclosed in JP 2013-242526 A, JP 2015-212807 A, JP 2018-173545 A, and International Publication No. 2018 / 181566 can be used. Preferred silane coupling agents include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, paraaminophenyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-isocyanatepropyltriethoxysilane, or 3-ureidopropyltriethoxysilane.

[0182] In addition to the additives described above, a compound having a cyclocarbonate group, a hydroxyalkylamide moiety, or a hydroxyl group can be added for the purpose of increasing the strength of the alignment film or stabilizing the electrical characteristics of the liquid crystal display element for a long period of time. Specific compounds include those disclosed in JP 2016-118753 A and WO 2017 / 110976 A. Preferred compounds 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 even more preferably 1 to 10% by weight, of the polyamic acid or its derivative. TIFF0007663449000135.tif88126

[0183] In addition, when improved antistatic properties are required, antistatic agents can be used, and when imidization is to proceed at low temperatures, imidization catalysts can be used, such as those disclosed in JP2013-242526A.

[0184] <Liquid crystal alignment film> Next, the liquid crystal alignment film of the present invention will be described. The liquid crystal alignment film of the present invention is formed using the liquid crystal alignment agent of the present invention. When the liquid crystal alignment agent of the present invention is used to form a liquid crystal alignment film, heating and baking causes an imidization reaction, and a polyimide-based liquid crystal alignment film can be formed. The liquid crystal alignment agent of the present invention is suitable as a liquid crystal alignment agent for photo-alignment, and a photo-alignment method can be applied to the alignment treatment in the process of forming the liquid crystal alignment film.

[0185] Hereinafter, a method for forming a liquid crystal alignment film using the photo-alignment liquid crystal aligning agent of the present invention will be described.

[0186] The liquid crystal alignment film of the present invention can be obtained by a normal method for preparing a liquid crystal alignment film from a liquid crystal alignment agent for photo-alignment.The liquid crystal alignment film of the present invention can be obtained, for example, through a process of forming a coating film of the liquid crystal alignment agent for photo-alignment of the present invention, a process of heating and drying the coating film to form a film of the liquid crystal alignment agent, a process of irradiating the film of the liquid crystal alignment agent with light to impart anisotropy, and a process of heating and baking the film of the liquid crystal alignment agent imparted with anisotropy.

[0187] The coating film can be formed by applying the liquid crystal alignment agent of the present invention to a substrate of a liquid crystal display element in the same manner as in the preparation of a normal liquid crystal alignment film. 2 O 3 -ZnO), IGZO (In-Ga-ZnO 4 Examples of the substrate include a substrate made of glass, silicon nitride, acrylic, polycarbonate, polyimide, etc., on which an electrode such as a 1) electrode or a color filter may be provided.

[0188] Generally known methods for applying a liquid crystal alignment agent to a substrate include a spinner method, a printing method, a dipping method, a dropping method, an inkjet method, etc. These methods are also applicable to the present invention.

[0189] The heat drying step is generally known to be a method of heat treatment in an oven or an infrared furnace, a method of heat treatment on a hot plate, etc. The heat drying step is preferably carried out at a temperature within a range in which the solvent can evaporate, and more preferably at a temperature relatively lower than the temperature in the heat baking step. Specifically, the heat drying temperature is preferably in the range of 30°C to 150°C, more preferably in the range of 50°C to 120°C.

[0190] The heating and baking step can be carried out under conditions necessary for the polyamic acid or its derivative to undergo an imidization reaction. For baking of the coating film, a method of heating in an oven or an infrared furnace, a method of heating on a hot plate, etc. are generally known. These methods can also be applied to the present invention. In general, the baking is preferably carried out at a temperature of about 90 to 300°C for 1 minute to 3 hours, more preferably 120 to 280°C, and even more preferably 150 to 250°C.

[0191] When it is important to improve the anisotropy of the film or the afterimage characteristics when a liquid crystal display device is manufactured, it is preferable to raise the temperature gradually in the heating step, for example, by heating and baking at different temperatures multiple times while raising the temperature stepwise, or by heating while changing the temperature from a low temperature to a high temperature. Also, both heating methods may be combined.

[0192] When firing is performed multiple times at different temperatures, multiple heating devices set to different temperatures may be used, or one heating device may be used and the temperature may be changed sequentially to different temperatures.

[0193] When firing is performed multiple times at different temperatures, the initial firing temperature is preferably 90 to 180 ° C, and the final temperature is preferably 185 ° C to 300 ° C. For example, it is preferable to heat and fire at 110 ° C and then heat and fire at 220 ° C, heat and fire at 110 ° C and then heat and fire at 230 ° C, heat and fire at 130 ° C and then heat and fire at 220 ° C, heat and fire at 150 ° C and then heat and fire at 200 ° C, heat and fire at 150 ° C and then heat and fire at 220 ° C, heat and fire at 150 ° C and then heat and fire at 230 ° C, or heat and fire at 170 ° C and then heat and fire at 200 ° C. It is also preferable to heat and fire the product in more stages while gradually increasing the temperature. When heating and firing is performed in two or more stages with different heating temperatures, the heating time in each heating step is preferably 5 to 30 minutes.

[0194] When firing is performed by changing the temperature from a low temperature to a high temperature, the initial temperature is preferably 90 to 180°C. The final temperature is preferably 185 to 300°C, more preferably 190 to 230°C. The heating time is preferably 5 to 60 minutes, more preferably 20 to 60 minutes. The temperature rise speed can be, for example, 0.5°C / min to 40°C / min. The temperature rise speed during the temperature rise does not have to be constant.

[0195] In the method for forming a liquid crystal alignment film of the present invention, a known photoalignment method can be suitably used as a means for imparting anisotropy to a thin film in order to align liquid crystals in one direction relative to the horizontal and / or vertical directions.

[0196] The method for forming the liquid crystal alignment film of the present invention using the photo-alignment method will be described in detail. The liquid crystal alignment film of the present invention using the photo-alignment method can be formed by heating and drying a coating film, irradiating the thin film with light to impart anisotropy to the thin film, and then heating and baking the film. Alternatively, the liquid crystal alignment film can be formed by heating and drying a coating film, heating and baking the film, and then irradiating the thin film with light.

[0197] Furthermore, in order to increase the liquid crystal alignment ability of the liquid crystal alignment film, the coating film can be irradiated with light while being heated. The light irradiation can be performed in the step of heating and drying the coating film or in the step of heating and baking, or between the heating and baking steps. The heating temperature when irradiating with light in the step of heating and drying the coating film or in the step of heating and baking can be determined by referring to the description of the heating and baking step above. The heating temperature when irradiating with light between the heating and baking step is preferably in the range of 30°C to 150°C, more preferably in the range of 50°C to 110°C.

[0198] The light used in the light irradiation step in the photo-alignment method may be, for example, ultraviolet light or visible light including light having a wavelength of 150 to 800 nm. The light is not particularly limited as long as it is light capable of imparting liquid crystal alignment ability to the thin film, but when it is desired to exert a strong alignment control force on the liquid crystal, polarized light is preferable, and linearly polarized light is more preferable.

[0199] The irradiation dose of the polarized light in the light irradiation step is 0.05 to 10 J / cm 2 is preferably 0.1 to 5 J / cm 2 is more preferable. The wavelength of the polarized light is preferably changed appropriately depending on the compound having a photoreactive structure. When the compound represented by formula (2) is used, the wavelength of the polarized light is preferably 200 to 400 nm, more preferably 300 to 400 nm. When the compound represented by formula (3) is used, the wavelength of the polarized light is preferably 150 to 350 nm, more preferably 200 to 300 nm. The irradiation angle of the polarized light to the film surface is not particularly limited, but when it is desired to express a strong alignment control force for the liquid crystal, it is preferable that the irradiation angle is as perpendicular as possible to the film surface from the viewpoint of shortening the alignment treatment time. In addition, the liquid crystal alignment film of the present invention can align the liquid crystal in a direction perpendicular to the polarization direction of the linearly polarized light by irradiating it with linearly polarized light.

[0200] The light source used in the light irradiation process can be, without limitation, an ultra-high pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a 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, an LED lamp, a sodium lamp, a microwave excited electrodeless lamp, and the like.

[0201] The liquid crystal alignment film of the present invention can be suitably obtained by a method further including steps other than the steps described above.

[0202] The liquid crystal alignment film of the present invention does not necessarily require a step of washing the film after baking or light irradiation with a washing solution, but a washing step can be provided for the convenience of other steps. Examples of the washing method using a washing solution include brushing, jet spray, steam washing, and ultrasonic washing. These methods may be performed alone or in combination. As the washing solution, pure water or various alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol, aromatic hydrocarbons such as benzene, toluene, and xylene, halogen-based solvents such as methylene chloride, and ketones such as acetone and methyl ethyl ketone can be used, but are not limited to these. Of course, these washing solutions are sufficiently purified and have few impurities. Such a washing method can also be applied to the washing step in the formation of the liquid crystal alignment film of the present invention.

[0203] In order to enhance the liquid crystal alignment ability of the liquid crystal alignment film of the present invention, an annealing treatment using heat or light can be used before or after the heating and baking process, or before or after irradiation with polarized or unpolarized light. In the annealing treatment, the annealing temperature is 30 to 180°C, preferably 50 to 150°C, and the time is preferably 1 minute to 2 hours. Examples of annealing light used in the annealing treatment include UV lamps, fluorescent lamps, and LED lamps. The amount of light irradiation is 0.3 to 10 J / cm. 2 It is preferable that:

[0204] The thickness of the liquid crystal alignment film of the present invention is not particularly limited, but is preferably 10 to 300 nm, more preferably 30 to 150 nm. The thickness of the liquid crystal alignment film of the present invention can be measured by a known thickness measuring device such as a step gauge or an ellipsometer.

[0205] The liquid crystal alignment film of the present invention is characterized by having a particularly large anisotropy of alignment. The magnitude of such anisotropy can be evaluated by a method using polarized IR described in JP-A-2005-275364, etc., and can also be evaluated by a method using ellipsometry. In detail, 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.

[0206] The liquid crystal alignment film of the present invention can be suitably used for controlling the alignment of a liquid crystal composition in a liquid crystal display element. In addition to the use of aligning a liquid crystal composition in a liquid crystal display element, it can be used for controlling the alignment of a liquid crystal material in all other liquid crystal elements such as a liquid crystal antenna, a light control window, an optical compensation material, a variable phase shifter, etc. In addition, since the liquid crystal alignment film of the present invention has a large anisotropy, it can be used alone as an optical compensation material.

[0207] <Liquid crystal display element> The liquid crystal display element 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 its excellent contrast.

[0208] The liquid crystal display element of the present invention will be described in detail. The present invention is a liquid crystal display element having a pair of substrates arranged opposite to each other, electrodes formed on one or both of the opposing surfaces of each of the pair of substrates, a liquid crystal alignment film formed on the opposing surface of each of the pair of substrates, a liquid crystal layer formed between the pair of substrates, a pair of polarizing films arranged to sandwich the opposing substrates, a backlight, and a driving device, in which the liquid crystal alignment film is composed of the liquid crystal alignment film of the present invention.

[0209] The electrode is not particularly limited as long as it is an electrode formed on one side of the substrate. Examples of such electrodes include ITO and metal deposition films. The electrode may be formed on the entire surface of one side of the substrate, or may be formed in a desired shape, for example, patterned. Examples of the desired shape of the electrode include a comb-shaped or zigzag structure. The electrode may be formed on one of the pair of substrates, or on both substrates. The form of electrode formation differs depending on the type of liquid crystal display element. For example, in the case of an IPS type liquid crystal display element (horizontal electric field type liquid crystal display element), an electrode is disposed on one of the pair of substrates, and in the case of other liquid crystal display elements, an electrode is disposed on both of the pair of substrates. The liquid crystal alignment film is formed on the substrate or the electrode.

[0210] In the case of a homogeneously aligned liquid crystal display element (e.g., IPS, FFS, etc.), the structure includes at least a backlight, a first polarizing film, a first substrate, a first liquid crystal alignment film, a liquid crystal layer, a second substrate, and a second polarizing film from the backlight side, and the polarizing axis of the polarizing film is set so that the polarizing axis of the first polarizing film (direction of polarized light absorption) crosses (preferably perpendicular) with the polarizing axis of the second polarizing film. At this time, the polarizing axis of the first polarizing film can be set so that it is parallel to the liquid crystal alignment direction or perpendicular to the liquid crystal alignment direction. A liquid crystal display element in which the polarizing axis of the first polarizing film is set so that it is parallel to the liquid crystal alignment direction is called O-mode, and a liquid crystal display element in which it is set so that it is perpendicular to the liquid crystal alignment direction is called E-mode. The liquid crystal alignment film of the present invention can be applied to either O-mode or E-mode, and can be selected according to the purpose.

[0211] Many photoisomerization materials use compounds with dichroism. Therefore, when the polarization axis of the polarized light irradiated to impart anisotropy to the liquid crystal alignment agent is aligned parallel to the polarization axis of the polarized light from the polarizing film arranged on the backlight side (when the liquid crystal alignment agent of the present invention is used, the O-mode arrangement is used), the transmittance of the liquid crystal alignment film in the light absorption wavelength range increases. Therefore, the transmittance of the liquid crystal display element can be further improved.

[0212] The liquid crystal layer is formed by sandwiching a liquid crystal composition between the pair of substrates on which the liquid crystal alignment film is formed, and when the liquid crystal layer is formed, a spacer such as fine particles or a resin sheet that is interposed between the pair of substrates to form an appropriate gap can be used as necessary.

[0213] Known methods for forming a liquid crystal layer include a vacuum injection method and an ODF (One Drop Fill) method.

[0214] In the vacuum injection method, a gap (cell gap) is provided so that the liquid crystal alignment film surfaces face each other, and a sealant is printed leaving an injection port for the liquid crystal, and then the substrates are bonded together. After the liquid crystal is injected into the cell gap defined by the substrate surface and the sealant using a vacuum pressure difference, the injection port is sealed to produce a liquid crystal display element.

[0215] In the ODF method, a sealant is printed on the outer periphery of the liquid crystal alignment film of one of the pair of substrates, liquid crystal is dropped on the area inside the sealant, and then the other substrate is attached so that the liquid crystal alignment film faces the other substrate. The liquid crystal is then spread over the entire surface of the substrate, and then the entire surface of the substrate is irradiated with ultraviolet light to harden the sealant, thereby producing a liquid crystal display element.

[0216] In addition to UV curing types, heat curing types are also known as sealants used for bonding substrates. The sealant can be printed by screen printing, for example.

[0217] 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 are described in Japanese Patent No. 3086228, Japanese Patent No. 2635435, JP-A-5-501735, JP-A-8-157826, JP-A-8-231960, JP-A-9-241644 (EP885272A1), JP-A-9-302346 (EP806466A1), JP-A-8-199168 (EP722998A1), and the like. ), JP-A-9-235552, JP-A-9-255956, JP-A-9-241643 (EP885271A1), JP-A-10-204016 (EP844229A1), JP-A-10-204436, JP-A-10-231482, JP-A-2000-087040, JP-A-2001-48822, and the like.

[0218] Preferable examples of the liquid crystal composition having negative dielectric anisotropy include those disclosed in JP-A-57-114532, JP-A-2-4725, JP-A-4-224885, JP-A-8-40953, JP-A-8-104869, JP-A-10-168076, JP-A-10-168453, JP-A-10-236989, JP-A-10-236990, JP-A-10-236992, JP-A-10-236993, JP-A-10-236994, JP-A-10-237000, JP-A-10-237004, JP-A-10-237024, JP-A-10-237035, JP-A-10-237075, and JP-A-10-237076. , JP-A-10-237448 (EP967261A1), JP-A-10-287874, JP-A-10-287875, JP-A-10-291945, JP-A-11-029581, JP-A-11-080049, JP-A-2000-256307, JP-A-2001-019965, JP-A-2001-072626, JP-A-2001-192657, JP-A-2010-037428, WO 2011 / 024666, WO 2010 / 072370, JP-T-2010-537010, JP-A-2012-077201, JP-A-2009-084362, and the like.

[0219] There is no problem in using a liquid crystal composition having a positive or negative dielectric anisotropy by adding one or more optically active compounds.

[0220] For example, the liquid crystal composition used in the liquid crystal display element of the present invention may further contain additives, for example, from the viewpoint of improving the alignment. Such additives include photopolymerizable monomers, optically active compounds, antioxidants, ultraviolet absorbers, dyes, defoamers, polymerization initiators, and polymerization inhibitors. Preferred photopolymerizable monomers, optically active compounds, antioxidants, ultraviolet absorbers, dyes, defoamers, polymerization initiators, and polymerization inhibitors include compounds disclosed in International Publication WO 2015 / 146330 and the like.

[0221] A polymerizable compound can be mixed into the liquid crystal composition to adapt it to a liquid crystal display element of PSA (polymer sustained alignment) mode. Preferred examples of the polymerizable compound are compounds having a polymerizable group, such as acrylate, methacrylate, vinyl compound, vinyloxy compound, propenyl ether, epoxy compound (oxirane, oxetane), and vinyl ketone. Preferred compounds include those disclosed in International Publication WO 2015 / 146330 and the like. EXAMPLES

[0222] The present invention will now be described with reference to examples, in which the evaluation methods and compounds used are as follows.

[0223] Weight average molecular weight (Mw) The weight average molecular weight of the polyamic acid was measured by the GPC method using a 2695 Separation Module 2414 Differential Refractometer (Waters) and calculated as polystyrene. The obtained polyamic acid was diluted with a phosphoric acid-DMF mixed solution (phosphoric acid / DMF=0.6 / 100: weight ratio) so that the polyamic acid concentration was about 2 wt%. The column used was HSPgel RT MB-M (Waters), and the mixed solution was used as a developer, and the measurement was performed under the conditions of a column temperature of 50°C and a flow rate of 0.40 mL / min. The standard polystyrene used was TSK standard polystyrene (Tosoh Corporation).

[0224] <Tetracarboxylic acid dianhydride> TIFF0007663449000136.tif68147

[0225] <Diamine> TIFF0007663449000137.tif36106 TIFF0007663449000138.tif22121

[0226] TIFF0007663449000139.tif3083 TIFF0007663449000140.tif25126

[0227] <Solvent> NMP: N-methyl-2-pyrrolidone BC: Butyl cellosolve (ethylene glycol monobutyl ether) <Additives> Additive 1: 1,3-bis(4,5-dihydro-2-oxazolyl)benzene Additive 2: (3,3',4,4'-diepoxy)bicyclohexyl

[0228] The compound represented by formula (1-1) was obtained by reference to the method described in International Publication No. 2019 / 172460.

[0229] The compound represented by formula (1-2) was obtained by reference to the method described in International Publication No. 2018 / 147373.

[0230] The compound represented by formula (3-4-1) is a compound in which the two esters on the cyclopropane ring in formula (3-4) are in a trans configuration. The compound represented by formula (3-4-1) was obtained by the following method. A solution of diethyl trans-1,2-cyclopropanedicarboxylate (10.0 g, 53.7 mmol) in ethanol (100 mL) was cooled on ice, and then a solution of sodium hydroxide (8.60 g, 215 mmol) in water (100 mL) was added. The mixture was gradually warmed to room temperature over 1 hour, and then stirred for 15 hours. After the reaction was completed, the reaction mixture was concentrated under reduced pressure, and ethanol was distilled off. The residue was again cooled on ice, and concentrated hydrochloric acid (20 mL) was added, followed by the addition of an excess amount of sodium chloride, and extraction with ethyl acetate (100 mL x 8 times). The organic layer was dried over anhydrous sodium sulfate, and then concentrated under reduced pressure to obtain a white solid of trans-1,2-cyclopropanedicarboxylic acid (yield 6.44 g, 92%). 1 H-NMR (400MHz, DMSO-d 6 ):δ1.89-1.77(m,2H),1.26-1.14(m,2H). TIFF0007663449000141.tif1992

[0231] Thionyl chloride (30 mL) was added to trans-1,2-cyclopropanedicarboxylic acid (6.00 g, 46.1 mmol), and the mixture was stirred at 70° C. for 4 hours. The mixture was then concentrated under reduced pressure to remove thionyl chloride, yielding crude trans-1,2-cyclopropanedicarboxylic acid chloride. This carboxylic acid chloride was dissolved in THF (90 mL), and the entire amount was used in the next reaction. Under an argon atmosphere, triethylamine (16.3 g, 161 mmol) was added to a solution of 4-nitrophenol (13.5 g, 96.8 mmol) in THF (100 mL) and cooled on ice. The mixture was stirred vigorously while the THF solution of the carboxylic acid chloride prepared above was added over 5 minutes, and then the mixture was warmed to room temperature and stirred at room temperature for 2.5 hours. A saturated aqueous solution of ammonium chloride (100 mL) was added to the reaction mixture and concentrated under reduced pressure. The residue was extracted with ethyl acetate (300 mL x 3 times) and then washed with saturated sodium bicarbonate (300 mL). The organic layer was dried over anhydrous sodium sulfate and concentrated under reduced pressure to obtain a pale yellow solid of trans-1,2-cyclopropanedicarboxylate di(4-nitrophenyl) (7.36 g). Furthermore, the solid remaining in the aqueous layer was filtered and washed with water to recover a pale yellow solid (6.72 g) of di(4-nitrophenyl)trans-1,2-cyclopropanedicarboxylate. By combining this with the above 7.36 g, dinitro compound 1 (di(4-nitrophenyl)trans-1,2-cyclopropanedicarboxylate) was obtained (total yield 14.1 g, 82% yield). 1 H-NMR (400MHz, CDCl 3 ):δ8.31(d,J=9.2Hz,4H),7.35(d,J=9.2Hz,4H),2.66-2.59(m,2H),1.86-1.78(m,2H). TIFF0007663449000142.tif18114

[0232] Under an argon atmosphere, tin(II) chloride dihydrate (84.8 g, 376 mmol) was added to a solution of dinitro compound 1 (14.0 g, 37.6 mmol) in ethyl acetate (370 mL), and the mixture was stirred under heating and reflux for 4 hours. After the reaction was completed, the reaction mixture was cooled to room temperature, added to a saturated aqueous sodium bicarbonate solution (1 L), and then extracted with ethyl acetate (300 mL x 3 times). The obtained organic layer was washed with a saturated aqueous sodium bicarbonate solution (300 mL) and saturated saline (300 mL), dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The obtained residue was purified by silica gel column chromatography using a mixed solvent of chloroform:methanol as an eluent, changing the ratio in the range of 100:0 to 95:5, to obtain the desired diamine compound (3-4-1) as a white solid (yield 8.50 g, 72%). Since the starting material, diethyl trans-1,2-cyclopropanedicarboxylate, has enantiomers, it is presumed that the material thus obtained is actually a mixture of the compound represented by formula (3-4-1) and its enantiomer. However, in this example, the two were used as they were without separating them. 1 H-NMR (400MHz, CDCl 3 ):δ6.90(d,J=8.8Hz,4H),6.67(d,J=8.8Hz,4H),3.64(brs,4H),2.53-2.47(m,2H),1.71-1.65(m,2H). TIFF0007663449000143.tif19136

[0233] Preparation of varnish The varnishes used in this example were prepared by the following procedure. Here, the varnishes A1 to A7 and R1 to R3 prepared in varnish 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 the film by irradiating polarized light of an appropriate wavelength after film formation. The blend varnishes B1 to B3 prepared in varnish preparation examples 11 to 13 are solutions of polyamic acid obtained without using a compound having a photoreactive chemical structure as a raw material, and are blended with the varnishes A1 to A7 or the varnishes R1 to R3 to be used for preparing blend-type liquid crystal alignment agents (alignment agents 7 to 11 and comparative alignment agents 4 to 5 described later).

[0234] [Varnish Preparation Example 1] Preparation of Varnish A1 In a 100mL three-neck flask equipped with a stirring blade and a nitrogen inlet tube, 2.058g of the compound represented by formula (2-1-1) was placed, and 34.0g of N-methyl-2-pyrrolidone was added and stirred. 1.971g of the compound represented by formula (1-1) and 1.971g of the compound represented by formula (AN-4-17) (m = 8) were added to this solution, and the mixture was stirred at room temperature for 12 hours. 30.0g of NMP and 30.0g of BC were added thereto, and the solution was heated and stirred at 60 ° C until the weight average molecular weight of the solute polymer reached the desired weight average molecular weight, to obtain a varnish A1 having a weight average molecular weight of the solute of approximately 13,400 and a resin concentration (solid concentration) of 6 wt%.

[0235] [Varnish Preparation Examples 2 to 13] Preparation of Varnishes A2 to A7, Varnishes R1 to R3, and Varnishes B1 to B3 Varnishes A2 to A7 and comparative varnishes R1 to R3 with a solid content concentration of 6% by weight 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 1. Varnishes B1 to B3 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 varnishes B1 to B3, the conditions of heating and stirring were adjusted so that the weight average molecular weight of the polymer was about 50,000. The weight average molecular weight of the generated polymer is shown in Tables 1 and 2. In Table 1, in a preparation example in which two or more compounds are listed as diamines, it means that all of the compounds were used together as diamines, and in a preparation example in which two or more compounds are listed as tetracarboxylic dianhydrides, it means that all of the compounds were used together as tetracarboxylic dianhydrides. The numbers in square brackets represent the compounding ratio (mol%), and blanks mean that the compound corresponding to that column was not used. The same applies to Table 2.

[0236] [Table 1]

[0237] [Table 2]

[0238] [Example 1] Varnish A1 was diluted with an NMP-BC mixed solution (NMP / BC = 7 / 3 weight ratio) to a solid content concentration of 4 wt%, and stirred to prepare alignment agent 1. The prepared liquid crystal alignment agent was applied to a glass substrate with FFS electrodes and a glass substrate with column spacers by the spinner method. After application, the substrate was heated at 60 °C for 80 seconds to evaporate the solvent, and then the substrate was irradiated with linearly polarized ultraviolet light from a vertical direction using a Multilight ML-501C / B manufactured by Ushio Inc. through a polarizer with a polarization wavelength range of 300 nm to 450 nm and a short wavelength cut filter with a cut-on wavelength of 280 nm. The exposure energy at this time was measured using an ultraviolet integrating light meter UIT-150 (receiver: UVD-S365) manufactured by Ushio Inc., and was set at a "standard exposure" of 2.0 ± 0.1 J / cm at a wavelength of 365 nm. 2 The exposure time was adjusted so that the liquid crystal composition was injected. After that, the substrate was baked at 220° C. for 30 minutes to form an alignment film with a thickness of about 100 nm. Next, the two substrates on which the alignment films were formed were laminated together with the surfaces on which the liquid crystal alignment films were formed facing each other, and a gap was provided between the opposing liquid crystal alignment films to inject the liquid crystal composition. At this time, the polarization directions of the linearly polarized light irradiated on each liquid crystal alignment film were parallel. Positive liquid crystal composition A was injected into these cells to prepare liquid crystal cells (liquid crystal display elements) with a cell thickness of 5 μm. The brightness-voltage characteristics (BV characteristics) of the prepared liquid crystal cells were measured, and the contrast (CR) was calculated using the ratio of the minimum brightness to the maximum brightness. The larger the CR value, the clearer the light and dark display and the better the contrast. CR=B max / B min In the formula, B max indicates the maximum brightness in the BV characteristic, and B min indicates the minimum luminance in the BV characteristics. Contrast (CR) was evaluated according to the following criteria. CR 3000 or more: Yes CR less than 3000: × Next, the amount of linearly polarized light is lower than the standard exposure amount above, "low exposure amount" 0.8 ± 0.1 J / cm 2A liquid crystal cell was prepared in exactly the same manner, except for adjusting the exposure time so that the contrast was calculated in the same manner. If the contrast is good at both the standard exposure dose and the low exposure dose, it means that the range of the suitable polarized light irradiation energy amount in the production of a liquid crystal display element is wider, and it means that the material is more preferable as a liquid crystal alignment agent for photoalignment. The evaluation results of the contrast in Examples 1 to 11 and Comparative Examples 1 to 5 are shown in Tables 3 and 4 together with the preparation conditions of the varnish.

[0239] [Example 2] 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 at 5 parts by weight based on the solid content at the same time as the NMP·BC mixed solution was added. A liquid crystal cell was prepared using alignment agent 2 in the same manner as in Example 1, and the contrast was measured and evaluated.

[0240] [Examples 3 to 5, Comparative Examples 1 to 2] Alignment agents 3 to 5 and comparative alignment agents 1 to 2 were prepared in the same manner as in Example 1, except that the varnishes shown in Table 3 were used instead of the varnish A1. For the alignment agents 3 to 5 and comparative alignment agents R1 and R2, liquid crystal cells were prepared in the same manner as in Example 1, and the contrast was measured and evaluated.

[0241] [Example 6, Comparative Example 3] Alignment agent 6 and comparative alignment agent R3 were prepared in the same manner as in Example 1, except that the varnishes shown in Table 3 were used instead of varnish A1. For alignment agent 6 and comparative alignment agent R3, linearly polarized ultraviolet light was irradiated from the vertical direction to the substrate through a polarizing plate with a polarization wavelength range of 230 nm to 310 nm, and the exposure energy was measured using a UV integrating light meter UIT-150 (receiver: UVD-S254) manufactured by Ushio Inc., and the "standard exposure amount" was 0.5±0.1 J / cm at a wavelength of 254 nm. 2 A liquid crystal cell was prepared in the same manner as in Example 1, except that the exposure time of linearly polarized light was adjusted so that the contrast was measured and evaluated. Next, a "low exposure amount" of 0.2±0.1 J / cm was measured, which is lower than the standard exposure amount. 2A liquid crystal cell was prepared in exactly the same manner except for adjusting the exposure time so that the contrast was obtained in the same manner.

[0242] [Example 7] Varnish A1 and varnish B1 were blended in a weight ratio of 3:7 to obtain a blend varnish with a solid content of 6% by weight. The blend was further diluted with an NMP-BC mixed solution (NMP / BC=7 / 3 weight ratio) to obtain a solid content of 4% by weight, and stirred to prepare alignment agent 7. A liquid crystal cell was fabricated in the same manner as in Example 1, except that alignment agent 7 was used instead of alignment agent 1, and the contrast was measured and evaluated.

[0243] [Example 8] Alignment agent 8 was prepared in the same manner as in Example 7, except that varnish A3 was used instead of varnish A1, and additive 2 was added at 5 parts by weight based on the solid content at the same time as the NMP·BC mixed solution was added. A liquid crystal cell was prepared using alignment agent 8 in the same manner as in Example 1, and the contrast was measured and evaluated.

[0244] [Examples 9 to 10, Comparative Example 4] Alignment agents 9 to 10 and comparative alignment agent 4 were prepared in the same manner as in Example 7, except that the varnishes shown in Table 4 were used instead of varnish A1 and varnish B1, and the blend ratio was changed to that shown in Table 4. For example, the blend ratio "4:6" in Example 9 in Table 4 indicates that varnish A4 and blend varnish B2 were blended at a weight ratio of 4:6. For each of alignment agents 9 to 10 and comparative alignment agent 4, liquid crystal cells were prepared in the same manner as in Example 1, and the contrast was measured and evaluated.

[0245] [Example 11, Comparative Example 5] Alignment agent 11 and comparative alignment agent 5 were prepared in the same manner as in Example 7, except that the varnishes shown in Table 4 were used instead of varnish A1 and varnish B1, and the blend ratio was changed to that shown in Table 4. For each of alignment agent 11 and comparative alignment agent 5, liquid crystal cells were prepared in the same manner as in Example 6, and the contrast was measured and evaluated.

[0246] <Positive Liquid Crystal Composition A> TIFF0007663449000146.tif18097 (Physical properties) Phase transition temperature NI: 100.1°C, dielectric anisotropy Δε: 5.1, refractive index anisotropy Δn: 0.093, viscosity η: 25.6 mPa s.

[0247] [Table 3]

[0248] [Table 4]

[0249] The contrast in Examples 1 to 11 was evaluated as "good" in both the liquid crystal cells prepared with the standard exposure amount and the low exposure amount. It was found that by using a polymer obtained by polymerizing a tetracarboxylic dianhydride represented by formula (1-1) or formula (1-2) with a compound having a photoreactive structure as a liquid crystal alignment agent for photoalignment, an alignment film that can realize a liquid crystal display element with high contrast even with a small exposure amount can be obtained. [Industrial Applicability]

[0250] By using the liquid crystal alignment agent for photo-alignment of the present invention, a liquid crystal alignment film that realizes a high-contrast liquid crystal display element can be produced even when the exposure energy of the photo-alignment treatment is low. The liquid crystal alignment agent for photo-alignment of the present invention can be suitably applied to a horizontal electric field type liquid crystal display element.

Claims

1. A liquid crystal alignment agent for photoalignment, comprising at least one polymer and a solvent, wherein at least one of the polymers is a polymer obtained by reacting a tetracarboxylic dianhydride with a diamine, A liquid crystal alignment agent for photo-alignment, comprising at least one compound represented by formula (1-1) or formula (1-2) and a compound having a photoreactive structure that imparts liquid crystal alignment properties to an alignment film by photoreaction, in a raw material composition used as a raw material for the polymer obtained by reacting the tetracarboxylic dianhydrides with the diamines, The compound having a photoreactive structure is at least one of a compound represented by formula (2) and a compound represented by formula (3). In formula (2), X is an alkylene group having 1 to 12 carbon atoms, and when the alkylene group has 2 or more carbon atoms, one or more non-adjacent —(CH 2 ) 2 — groups may be replaced with —O— or —NH—; R a and R b each independently represent a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, a fluorine atom, a methoxycarbonyl group, or a monovalent group represented by formula (P1-1) or formula (P1-2); R c each independently represents a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, a fluorine atom, or a monovalent group represented by formula (P1-1) or formula (P1-2); j is 0 or 1; and a to c each independently represent an integer of 0 to 2; In formula (P1-1) and formula (P1-2), R 6a , R 7a and R 8a each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or a substituted or unsubstituted alkoxycarbonyl group, R 6a , R 7a and R 8a may be the same or different, * represents the bonding position to the benzene ring in formula (2), In formula (2), a group that is not fixed to any carbon atom constituting a ring indicates that the group may be bonded to any carbon atom in the ring. In formula (3), R 1 and R 2 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a haloalkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms; R 1 and R 2 may be joined together to form an optionally substituted methylene group; each 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 from 0 to 4.

2. The liquid crystal aligning agent for photoalignment according to claim 1, wherein the compound represented by formula (2) is any one of formulas (2-1) to (2-3). In formula (2-1), R １ａ and R １ｃ each independently represents a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2), In formula (2-2), R ２ａ and R ２ｂ each independently represents a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2); R ２ｃ are each independently a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, or a fluorine atom; X １ is an alkylene group having 1 to 12 carbon atoms, and when the alkylene group has 2 or more carbon atoms, -(CH ２ ) ２ one or more non-adjacent -'s may be replaced by -O- or -NH-, k is an integer of 0 to 2, In formula (2-3), R ３ａ each independently represents a hydrogen atom or a monovalent group represented by formula (P1-1) or formula (P1-2); R ４ and R ５ are each independently a hydrogen atom or a fluorine atom, R ４ and R ５ cannot be a hydrogen atom at the same time, and R 3ｃ are each independently a hydrogen atom, a methyl group, a methoxy group, a trifluoromethyl group, or a fluorine atom; X １ is an alkylene group having 1 to 12 carbon atoms, and when the alkylene group has 2 or more carbon atoms, the alkylene group -(CH ２ ) ２ one or more non-adjacent -'s may be replaced by -O- or -NH-, m is an integer of 0 to 2, In formula (P1-1) and formula (P1-2), R ６ａ , R ７ａ and R ８ａ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkanoyl group, or a substituted or unsubstituted alkoxycarbonyl group; R ６ａ , R ７ａ and R ８ａ may be the same or different, * represents the bonding position to the benzene ring in formula (2-1), formula (2-2) or formula (2-3), In formula (2-1), (2-2) or (2-3), a group that is not bonded to any carbon atom constituting a ring means that the bonding position in the ring is arbitrary.

3. The liquid crystal aligning agent for photo-alignment according to claim 1 or 2, further comprising an additive.

4. The liquid crystal aligning agent for photo-alignment according to claim 3 , wherein the additive is at least one selected from the group consisting of oxazoline compounds and epoxy compounds.

5. A liquid crystal alignment film formed from the liquid crystal alignment agent for photo-alignment according to any one of claims 1 to 4.

6. A liquid crystal device comprising the liquid crystal alignment film according to claim 5 .

7. A method for producing a liquid crystal alignment film, comprising the steps of: applying the liquid crystal aligning agent for photo-alignment according to any one of claims 1 to 4 to a substrate; and irradiating the coating with polarized ultraviolet light.

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