Method for manufacturing liquid crystal alignment films, photoalignment agent, and liquid crystal element

Abstract

To provide a liquid crystal alignment agent that can give a liquid crystal alignment film having excellent liquid crystal alignment properties, touching durability and adhesion, and enables the production of a liquid crystal element with reduced bright dot defects.SOLUTION: A liquid crystal alignment film is produced by a method including the steps of: forming a coating layer with a liquid crystal alignment agent containing a polymer [A] having a moiety (a) represented by the formula (1); and irradiating the coating layer with light, to endow it with the ability to align liquid crystals. In the formula (1), A1 and A2 each represent a divalent aromatic ring group, where, A1 and / or A2 has a structure with a group represented by -OR1, -NR2R3 or -SR4 binding to an aromatic ring. B1 and B2 each represent a single bond, -O-, -S-, -NR5-, -CO-, *1-CO-O-, *1-O-CO-, *1-CS-O-, *1-O-CS-, *1-CO-NR6- or *1-NR6-CO-NR7-. X is a divalent hydrocarbon group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a liquid crystal alignment film and a photoalignment agent. and Liquid crystal element to child To relate to. [Background technology]

[0002] Liquid crystal elements are used in a wide range of applications, from relatively large display devices such as LCD televisions and information displays to small display devices such as smartphones. The performance of a liquid crystal element is determined by various characteristics such as the orientation of the liquid crystals, the size of the pre-tilt angle, and the voltage retention rate. In order to improve the performance of liquid crystal elements, conventional efforts have been made to improve the liquid crystal material as well as the liquid crystal alignment film used to align the liquid crystals in a specific direction (see, for example, Patent Documents 1 and 2).

[0003] Patent Document 1 discloses a liquid crystal alignment agent containing polyamic acid and its derivatives, which are reaction products of tetracarboxylic dianhydride and diamine, wherein the polyamic acid obtained using di-tert-butyl{[adipoylbis(azandiyl)]bis(5-amino-2,1-phenylene)}dicarbamate as the diamine is included in the liquid crystal alignment agent. Patent Document 2 also discloses a liquid crystal alignment agent containing polyimide obtained using 4,4'-[ethane-1,2-diylbis(oxy)]bis(3-methylaniline) as the diamine. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2014 / 104015 [Patent Document 2] International Publication No. 2017 / 047596 [Overview of the project] [Problems that the invention aims to solve]

[0005] One method for forming liquid crystal alignment films by imparting anisotropy to a film is the photo-alignment method. This method involves irradiating a radiation-sensitive organic thin film formed on a substrate with polarized or unpolarized radiation to impart anisotropy to the film, thereby controlling the orientation of liquid crystal molecules. Compared to the conventional rubbing method, this method suppresses the generation of dust and static electricity during the process, thus reducing display defects and yield reductions caused by dust and other factors. It also offers the advantage of uniformly imparting liquid crystal alignment ability to the organic thin film formed on the substrate. However, when applying the photo-alignment method, decomposition products of polymers and other materials are easily generated by light irradiation, leading to display defects (bright spots) caused by these decomposition products. To improve the quality of liquid crystal elements, it is necessary to suppress the generation of bright spots while maintaining excellent liquid crystal alignment, one of the fundamental characteristics.

[0006] In mobile applications such as smartphones and tablet PCs, narrow bezels are being pursued to achieve both a larger touch panel operating area and a smaller display device. One method for achieving narrow bezels is to form a liquid crystal alignment film across the entire substrate surface, and then apply a sealant to the liquid crystal alignment film to bond the substrates together. However, when a sealant is placed on the liquid crystal alignment film, force is more easily applied to the part of the alignment film where the sealant is placed. Therefore, if the mechanical properties or adhesion of the liquid crystal alignment film are poor, there is a concern that the substrates may easily delaminate from each other.

[0007] Furthermore, in recent years, touch panel systems have become the mainstream for liquid crystal elements used in smartphones and automotive applications, making them susceptible to external forces from user keystrokes. From the perspective of improving the reliability of liquid crystal elements, the liquid crystal alignment film that constitutes the liquid crystal element must be resistant to degradation of display quality caused by external forces and have good keystroke durability (also known as touch panel resistance).

[0008] The present invention has been made in view of the above problems, and a main object thereof is to provide a liquid crystal aligning agent capable of obtaining a liquid crystal alignment film excellent in liquid crystal alignment property, keying durability, and adhesion, and capable of manufacturing a liquid crystal element in which the occurrence of bright spot defects is suppressed.

Means for Solving the Problems

[0009] The present invention employs the following means to solve the above problems.

[0010] <1> A method for manufacturing a liquid crystal alignment film, including a step of forming a coating film with a liquid crystal aligning agent containing a polymer [A] having a partial structure (a) represented by the following formula (1), and a step of irradiating the coating film with light to impart liquid crystal aligning ability.

Chemical formula

[0011] <2> A photoaligning agent containing a polymer [A] having a substructure (a) represented by the above formula (1). <3> the above <1> A liquid crystal element comprising a liquid crystal alignment film manufactured by the method described above. <4> A polymer containing structural units derived from a diamine represented by the following formula (3). [ka] (In formula (3), A 3 and A 4 These are each independently divalent aromatic ring groups. However, A 3 and A 4 One or both of are -OR 1a or -NR 2a R 3a It has a structure in which a group represented by is bonded to an aromatic ring. 1a and R 2a These are each independently monovalent hydrocarbon groups. 3a is a hydrogen atom or a monovalent organic group. 3 and B 4 These are, independently, single bonds, -O-, -S-, and -NR bonds. 5a -, -CO-, * 1 -CO-O-, * 1 -O-CO-, * 1 -CS-O-, * 1 -O-CS-, * 1 -CO-NR 6a -or* 1 -NR 6a -CO-NR 7a - is R 5a R is a monovalent organic group. 6a and R 7a Each of these is independently a hydrogen atom or a monovalent organic group. 1 " is A 3 Or A 4 This represents a combination with B. Y is B3 When is -O-, it is an alkanediyl group having 1 or 2 carbon atoms, a divalent alicyclic hydrocarbon group, or a divalent aromatic hydrocarbon group, B 3 but* 1 In the case of -O-CO-, it is an alkanediyl group, a divalent alicyclic hydrocarbon group having an aliphatic hydrocarbon ring with 4 or more carbon atoms, or a divalent aromatic hydrocarbon group, B 3 -O- and * 1 (It is a divalent hydrocarbon group in cases other than -O-CO-.) <5> A diamine represented by the above formula (3). [Effects of the Invention]

[0012] According to the present invention, it is possible to obtain a liquid crystal alignment film with excellent liquid crystal alignment, keystroke durability, and adhesion, and a liquid crystal element in which the occurrence of bright spot defects is suppressed. [Modes for carrying out the invention]

[0013] The liquid crystal alignment agent and liquid crystal alignment film manufacturing method of this disclosure will be described below.

[0014] In this specification, "hydrocarbon group" includes linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. "Linear hydrocarbon group" means a linear hydrocarbon group or a branched hydrocarbon group that does not contain a cyclic structure in its main chain and consists only of a linear structure. However, linear hydrocarbon groups may be saturated or unsaturated. "Alicyclic hydrocarbon group" means a hydrocarbon group that contains only the structure of an alicyclic hydrocarbon as its ring structure and does not contain an aromatic ring structure. However, an alicyclic hydrocarbon group does not have to consist only of the structure of an alicyclic hydrocarbon, and may also include those that have a linear structure as part of it. "Aromatic hydrocarbon group" means a hydrocarbon group that contains an aromatic ring structure as its ring structure. However, an aromatic hydrocarbon group does not have to consist only of an aromatic ring structure, and may include a linear structure or an alicyclic hydrocarbon structure as part of it. "Aromatic ring" means an aromatic hydrocarbon ring and an aromatic heterocycle. "Organic group" means an atomic group obtained by removing any hydrogen atom from a carbon-containing compound (i.e., an organic compound).

[0015] "Liquid Crystal Alignment Agent" The liquid crystal alignment agent of the present disclosure contains a polymer [A] having a partial structure (a) represented by the following formula (1). [Chemical formula] (In formula (1), A 1 and A 2 are each independently a divalent aromatic ring group. However, one or both of A 1 and A 2 has a structure in which a group represented by -OR 1 , -NR 2 R 3 or -SR 4 is bonded to the aromatic ring. R 1 , R 2 and R 4 are each independently a hydrogen atom or a monovalent organic group. R 3 is a monovalent organic group. B 1 and B 2 are each independently a single bond, -O-, -S-, -NR 5 -, -CO-, * 1 -CO-O-, * 1 -O-CO-, * 1 -CS-O-, * 1 -O-CS-, * 1 -CO-NR 6 - or * 1 -NR 6 -CO-NR 7 -. "* 1 " represents a bond to A 1 or A 2 . R 5 , R 6 and R 7 are each independently a hydrogen atom or a monovalent organic group. X is a divalent hydrocarbon group. "*" represents a bond.)

[0016] The liquid crystal aligning agent of the present disclosure is particularly suitable as a liquid crystal aligning agent (i.e., photo-aligning agent) for forming a liquid crystal alignment film by photo-alignment treatment. First, each component contained in the liquid crystal aligning agent of the present disclosure and other components optionally blended as needed will be described below.

[0017] <Polymer [A]> ·Regarding the partial structure (a) In formula (1), A 1 and A 2 Examples of the divalent aromatic ring group represented by include divalent aromatic hydrocarbon groups and divalent aromatic heterocyclic groups. Examples of the divalent aromatic hydrocarbon group include groups formed by removing any hydrogen atom bonded to a carbon atom constituting a benzene ring, a biphenyl ring, a naphthalene ring, or an anthracene ring. Examples of the divalent nitrogen-containing aromatic heterocyclic group include groups formed by removing any hydrogen atom bonded to a carbon atom constituting a pyridine ring, a pyrimidine ring, a pyridazine ring, or a pyrazine ring. A 1 and A 2 Among these, the divalent aromatic ring group represented by is preferably a divalent aromatic hydrocarbon group, and more preferably a group formed by removing any hydrogen atom bonded to a carbon atom constituting a benzene ring.

[0018] A 1 and A 2 One or both of and have a structure in which an electron-donating group (hereinafter also referred to as "substituent F1") represented by -OR 1 , -NR 2 R 3 or -SR 4 is bonded to an aromatic ring. By introducing a structure in which substituent F1 is directly bonded to an aromatic ring into the polymer, the thermal rearrangement property is improved, and it is presumed that the liquid crystal alignment property is improved. Also, by introducing substituent F1, the crystallinity is lowered, and the structure becomes such that stress is easily relaxed, resulting in increased strength and improved keying durability. In addition, by introducing substituent F1, the solubility of the polymer can be increased, and the polymer can be made highly sensitive.

[0019] R 1 、R2 , R 3 or R 4 The monovalent organic group represented by is preferably a monovalent hydrocarbon group or a thermally desorbable group having 1 to 10 carbon atoms, more preferably a monovalent hydrocarbon group or a thermally desorbable group having 1 to 6 carbon atoms, and even more preferably a monovalent hydrocarbon group or a thermally desorbable group having 1 to 5 carbon atoms, from the viewpoint of sufficiently obtaining the effect of improving liquid crystal alignment. A thermally desorbable group is a group that is desorbed by heat and replaced by a hydrogen atom. From the viewpoint of improving thermal desorption and reducing the amount of residual portion in the film after desorption, the thermally desorbable group is preferably having 15 carbon atoms or less, and more preferably 10 carbon atoms or less.

[0020] Specific examples of monovalent hydrocarbon groups having 1 to 10 carbon atoms include alkyl groups having 1 to 10 carbon atoms, cycloalkyl groups having 3 to 10 carbon atoms, and aryl groups having 6 to 10 carbon atoms. Of these, monovalent hydrocarbon groups having 1 to 6 carbon atoms are preferred, alkyl groups or phenyl groups having 1 to 5 carbon atoms are more preferred, and alkyl groups having 1 to 3 carbon atoms are even more preferred.

[0021] R 1 Specific examples of groups that are thermally leaving groups include acetyl, benzoyl, benzyl, p-methoxyphenylbenzyl, methoxymethyl, tert-butoxycarbonyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, and trityl groups. 1 The thermally leaving group represented by is preferably an acetyl group, a methoxymethyl group, or a tert-butoxycarbonyl group, and more preferably an acetyl group or a tert-butoxycarbonyl group (Boc group).

[0022] R 2 , R 3Specific examples of thermally detachable groups include carbamate protecting groups, acyl protecting groups, amide protecting groups, imide protecting groups, and sulfonamide protecting groups. Of these, carbamate protecting groups are preferred due to their high thermal detachability. Specific examples include tert-butoxycarbonyl group, methoxycarbonyl group, benzyloxycarbonyl group, 1,1-dimethyl-2-haloethyloxycarbonyl group, allyloxycarbonyl group, 2-(trimethylsilyl)ethoxycarbonyl group, 9-fluorenylmethyloxycarbonyl group, and allyloxycarbonyl group. Among these, tert-butoxycarbonyl group (Boc group) is particularly preferred due to its excellent thermal detachability and the ability to minimize the amount of the detached portion remaining in the film.

[0023] R 4 Specific examples of groups that are thermally leaving groups include benzyloxymethyl group, p-methoxybenzyloxymethyl group, tert-butoxycarbonyl group, and trimethylsilyl group. Of these, the tert-butoxycarbonyl group (Boc group) is preferred.

[0024] From the perspective of improving liquid crystal alignment, R 1 , R 2 and R 4 Among the above, it is preferably a hydrogen atom, a monovalent hydrocarbon group having 1 to 6 carbon atoms, or a thermally desorbable group, and more preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a phenyl group, or a thermally desorbable group. 3 It is preferably a monovalent hydrocarbon group having 1 to 6 carbon atoms or a thermally desorbable group, and more preferably an alkyl group, phenyl group, or thermally desorbable group having 1 to 3 carbon atoms.

[0025] Specific examples of substituent F1 include hydroxyl groups, alkoxy groups having 1 to 5 carbon atoms, alkylcarbonyloxy groups having 2 to 5 carbon atoms (acetoxy group, propionyloxy group, etc.), tert-butoxycarbonyloxy groups, alkylamino groups having 1 to 5 carbon atoms, dimethylamino groups, diethylamino groups, alkylamide groups having 2 to 5 carbon atoms, N-(tert-butoxycarbonyl)amino groups, N-(tert-butoxycarbonyl)-N-methylamino groups, N-(tert-butoxycarbonyl)-N-ethylamino groups, N,N-di(tert-butoxycarbonyl)amino groups, thiol groups, and alkylthio groups having 1 to 5 carbon atoms.

[0026] Substituent F1 can significantly improve liquid crystal alignment, and among the above, -OR 1 or -NR 2 R 3 Preferably, -OR 1 This is preferable.

[0027] From the perspective of obtaining good liquid crystal alignment and adhesion effects while also improving the effect of suppressing bright spots and improving keystroke durability, A 1 and A 2 It is preferable that both have substituents F1 bonded to the aromatic ring. 1 The number of substituents F1 and A 2 The number of substituents F1 in each molecule is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1.

[0028] The bonding position of substituent F1 in the aromatic ring is not particularly limited. The atom to which substituent F1 is bonded and B 1 or B 2 (B 1 , B 2 In the case of a single bond, if X) is adjacent to the atom to which it is bonded, it is preferable in that the sensitivity to light can be increased and a liquid crystal element exhibiting good liquid crystal alignment can be obtained. 1 and A 2 Preferably, the aromatic ring portion does not have any further substituents other than substituent F1.

[0029] B1 and B 2 Regarding -NR 5 -, * 1 -CO-NR 6 -, * 1 -NR 6 -CO-NR 7 - completeR 5 , R 6 or R 7 If is a monovalent organic group, it is preferable that the monovalent organic group is a monovalent hydrocarbon group having 1 to 10 carbon atoms or a thermally desorbable group. 5 , R 6 or R 7 Specific and preferred examples of monovalent hydrocarbon groups or thermally desorbable groups having 1 to 10 carbon atoms include R 2 , R 3 The base described as a specific example and preferred example is R. 5 , R 6 and R 7 The group is preferably a hydrogen atom, a C1-C3 alkyl group, or a thermally desorbable group, and more preferably a C1-C3 alkyl group or a tert-butoxycarbonyl group.

[0030] B 1 and B 2 From the viewpoint of obtaining liquid crystal elements that exhibit good liquid crystal alignment, among them -O-, -S-, and -NR 5 -, -CO-, * 1 -CO-O-, * 1 -O-CO-, * 1 -CS-O-, * 1 -O-CS-, * 1 -CO-NR 6 -or* 1 -NR 6 -CO-NR 7 - Preferably -O-, -S- or -NR 5 - is more preferable.

[0031] Examples of divalent hydrocarbon groups represented by X include chain hydrocarbon groups having 1 to 18 carbon atoms, alicyclic hydrocarbon groups having 3 to 18 carbon atoms, and aromatic hydrocarbon groups having 6 to 18 carbon atoms. In terms of forming a liquid crystal alignment film with high liquid crystal alignment and keying durability, X is preferably a chain hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, or an aromatic hydrocarbon group having 6 to 12 carbon atoms. In terms of achieving even better liquid crystal alignment and higher film density, a linear alkanediyl group having 1 to 5 carbon atoms is more preferable, and a methylene group or a 1,2-ethylene group is even more preferable.

[0032] In terms of achieving a greater improvement in liquid crystal alignment and keystroke durability, it is preferable that polymer [A] has a substructure (a) in its main chain, that is, that substructure (a) constitutes a part of the main chain of polymer [A]. The main skeleton of polymer [A] is not particularly limited. In terms of ease of introducing substructure (a) into the main chain of the polymer, the ability to form a liquid crystal alignment film with high affinity for liquid crystals and high mechanical strength, and a high degree of freedom in monomer selection, it is preferable that polymer [A] has structural units derived from a diamine having substructure (a) (hereinafter also referred to as "specific diamine"), and specifically, it is preferable that it has structural units derived from a compound represented by the following formula (2). [ka] (In formula (2), A 1 , A 2 , B 1 , B 2 And X is equivalent to equation (1) above.

[0033] Here, "main chain" refers to the "stem" portion of the polymer, which consists of the longest chain of atoms. It is permissible for this "stem" portion to contain a ring structure. In other words, "having substructure (a) in the main chain" means that substructure (a) constitutes a part of the main chain. "Side chain" refers to a portion of the polymer that branches off from the "stem."

[0034] The specific diamine is particularly preferably a compound represented by the following formula (2A). [ka] (In formula (2A), Z 1 and Z 2 These are, independently, -OR 1 , -NR 2 R 3 or -SR 4 This is a group represented by . k1 and k2 are independently 1 or 2. When k1 is 2, multiple Z 1 They are the same or different. If k2 is 2, there are multiple Z 2 They are the same or different. R 1 , R 2 , R 3 , R 4 , B 1 , B 2 And X is equivalent to equation (1) above.

[0035] In equation (2A), Z 1 and Z 2 is -OR 1 or -NR 2 R 3 It is preferable that the group is represented by .

[0036] Z 1 and Z 2 ga-OR 1 In the case of a group represented by R, 1 It is preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a phenyl group, or a thermally detachable group, more preferably an alkyl group having 1 to 5 carbon atoms, and even more preferably an alkyl group having 1 to 3 carbon atoms. Also, B 1 and B 2 -O-, -S-, -NR 5 -, -CO-, * 1 -CO-O-, * 1 -O-CO-, * 1 -CS-O-, * 1 -O-CS-, * 1 -CO-NR 6 -or* 1 -NR 6 -CO-NR 7 - Preferably -O-, -S- or -NR5 - is more preferable. X is preferably a carbon-1 or carbon-2 alkanediyl group, a divalent alicyclic hydrocarbon group, or a divalent aromatic hydrocarbon group, and more preferably a carbon-1 or carbon-2 alkanediyl group.

[0037] Z 1 and Z 2 ga-NR 2 R 3 In the case of a group represented by R, 2 R is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a phenyl group, or a thermally desorbable group. 3 It is preferable that is an alkyl group having 1 to 3 carbon atoms, a phenyl group, or a thermally detachable group. Also, B 1 and B 2 -O-, -S-, or -NR 5 It is preferable that it be -, and more preferably -O-. X is preferably an alkanediyl group having 1 to 5 carbon atoms, a divalent alicyclic hydrocarbon group, or a divalent aromatic hydrocarbon group, more preferably an alkanediyl group having 1 to 5 carbon atoms, and even more preferably an alkanediyl group having 1 or 2 carbon atoms.

[0038] Specific examples of specific diamines include compounds represented by the following formulas (4-1) to (4-24). In these formulas, "Boc" represents a tert-butoxycarbonyl group (the same applies hereafter). [ka] [ka] [ka] (In the formula, n is an integer between 1 and 18.)

[0039] In the compounds represented by formulas (4-1) to (4-24) above, the bonding position of substituent F1 on the benzene ring is not particularly limited. The bonding position of substituent F1 is any other group other than the primary amino group (i.e., B in formula (1) above). 1 or B 2(B 1 , B 2 When it is a single bond, it is preferable that it is at the 2- or 3-position relative to X). In particular, when the bond position of substituent F1 is at the 2-position relative to a group other than the primary amino group, it is preferable because it can increase sensitivity and further improve liquid crystal orientation.

[0040] In polymer [A], the content of structural units having substructure (a) (hereinafter also referred to as "structural units (Ua)") is preferably 2 moles or more per 100 moles of total monomer units in polymer [A], from the viewpoint of obtaining a liquid crystal element in which the liquid crystal alignment film has a sufficiently high effect on improving liquid crystal alignment, adhesion, and keystroke durability, and in which the generation of bright spots is sufficiently suppressed. The content of structural units (Ua) is more preferably 5 moles or more, and even more preferably 10 moles or more, per 100 moles of total monomer units in polymer [A]. Furthermore, the content of structural units (Ua) can be appropriately set according to the main chain of polymer [A], but is, for example, 50 moles or less per 100 moles of total monomer units in polymer [A]. Note that polymer [A] may have only one type of structural unit (Ua), or two or more types.

[0041] Specific diamines can be synthesized by appropriately combining standard organic chemistry methods. One example is to synthesize a dinitro compound having a nitro group instead of the primary amino group of a diamine having substructure (a), and then aminate the nitro group of the resulting dinitro compound using a suitable reducing system.

[0042] The method for synthesizing the dinitro compound can be appropriately selected depending on the target compound. For example, a method of reacting a hydroxyl group-containing compound having an aromatic ring structure to which a substituent F1 is attached with a halide having group X, preferably in an organic solvent, in the presence of a base and optionally a catalyst; a method of reacting a hydroxyl group-containing compound having an aromatic ring structure to which a substituent F1 is attached with a tosyl group-containing compound having group X, preferably in an organic solvent, in the presence of a base and optionally a catalyst; a method of condensing an acid halide having an aromatic ring structure to which a substituent F1 is attached with an amino group-containing compound having group X, preferably in an organic solvent, in the presence of a base and optionally a catalyst; a method of condensing a carboxylic acid having an aromatic ring structure to which a substituent F1 is attached with an amino group-containing compound having group X, preferably in an organic solvent, in the presence of a base and optionally a catalyst, and so on.

[0043] The reduction reaction of dinitro compounds can preferably be carried out in an organic solvent using a catalyst such as palladium-carbon, platinum oxide, zinc, iron, tin, or nickel. Examples of organic solvents that can be used here include ethyl acetate, toluene, tetrahydrofuran, and alcohols. However, the synthesis procedure for specific diamines is not limited to the above method.

[0044] According to this disclosure, a diamine represented by the following formula (3) is provided. [ka] (In formula (3), A 3 and A 4 These are each independently divalent aromatic ring groups. However, A 3 and A 4 One or both of are -OR 1a or -NR 2a R 3a It has a structure in which a group represented by is bonded to an aromatic ring. 1a and R 2a These are each independently monovalent hydrocarbon groups. 3a is a hydrogen atom or a monovalent organic group. 3 and B 4These are, independently, single bonds, -O-, -S-, and -NR bonds. 5a -, -CO-, * 1 -CO-O-, * 1 -O-CO-, * 1 -CS-O-, * 1 -O-CS-, * 1 -CO-NR 6a -or* 1 -NR 6a -CO-NR 7a - is R 5a R is a monovalent organic group. 6a and R 7a Each of these is independently a hydrogen atom or a monovalent organic group. 1 " is A 3 Or A 4 This represents a combination with B. Y is B 3 When is -O-, it is an alkanediyl group having 1 or 2 carbon atoms, a divalent alicyclic hydrocarbon group, or a divalent aromatic hydrocarbon group, B 3 but* 1 In the case of -O-CO-, it is an alkanediyl group, a divalent alicyclic hydrocarbon group having an aliphatic hydrocarbon ring with 4 or more carbon atoms, or a divalent aromatic hydrocarbon group, B 3 -O- and * 1 (It is a divalent hydrocarbon group in cases other than -O-CO-.)

[0045] In equation (3) above, R 1a and R 2a A monovalent hydrocarbon group represented by, and R 3a For specific and preferred examples of monovalent organic groups represented by formula (1), see R in formula (1). 1 , R 2 and R 3 Examples of monovalent hydrocarbon groups and monovalent organic groups, as exemplified above, include groups similar to those described in the examples and preferred examples. 1a and R 2a The group is preferably a monovalent hydrocarbon group having 1 to 6 carbon atoms, more preferably an alkyl group and a phenyl group having 1 to 5 carbon atoms, and even more preferably an alkyl group having 1 to 3 carbon atoms. 3aThe group is preferably a hydrogen atom, a C1-C5 alkyl group, a phenyl group, or a thermally desorbable group, and more preferably a hydrogen atom, a C1-C3 alkyl group, or a tert-butoxycarbonyl group.

[0046] B 3 and B 4 For specific and preferred examples, see B in formula (1). 1 and B 2 The explanation applies. Specific examples of a divalent hydrocarbon group represented by Y include the group represented by X in formula (1) and the same group as the example group.

[0047] B 3 When -O-, Y is preferably a C1 or C2 alkanediyl group, a divalent alicyclic hydrocarbon group having an aliphatic hydrocarbon ring with 4 or more carbon atoms, or a divalent aromatic hydrocarbon group, from the viewpoint of improving liquid crystal alignment. As a divalent alicyclic hydrocarbon group having an aliphatic hydrocarbon ring with 4 or more carbon atoms, it is preferable to have a cyclohexane ring from the viewpoint of achieving good liquid crystal alignment and high film density. 3 If is -O-, then Y is more preferably a methylene group or an ethylene group among these.

[0048] B 3 but* 1 In the case of -O-CO-, Y is preferably a linear alkanediyl group having 1 to 5 carbon atoms, and more preferably a methylene group or an ethylene group. 3 -O- and * 1 If Y is not -O-CO-, Y is preferably a chain hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, or an aromatic hydrocarbon group having 6 to 12 carbon atoms. A linear alkanediyl group having 1 to 5 carbon atoms is more preferable in terms of improving liquid crystal alignment and increasing film density, and a methylene group or ethylene group is even more preferable.

[0049] The diamine represented by formula (3) is particularly preferably the compound represented by the following formula (3A). [ka] (In formula (3A), Z 3 and Z 4 These are, independently, -OR 1a or -NR 2a R 3a This is a group represented by . k3 and k4 are independently 1 or 2. When k3 is 2, multiple Z 3 They are the same or different. If k4 is 2, there are multiple Z 4 They are the same or different. R 1a , R 2a , R 3a , B 3 , B 4 And Y is equivalent to equation (3) above.

[0050] Specific examples of diamines represented by formula (3) include compounds in formulas (4-1) to (4-3), (4-6), (4-10), and (4-23) in which n is 1 or 2; and compounds represented by formulas (4-13), (4-18), and (4-22), respectively.

[0051] Polymer [A] is preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide, as it has high affinity and mechanical strength with liquid crystals and can form a highly reliable liquid crystal alignment film.

[0052] • Polyamic acid When polymer [A] is a polyamic acid, the polyamic acid (hereinafter also referred to as "polyamic acid [A]") can be obtained by reacting a tetracarboxylic dianhydride with a diamine compound containing a specific diamine.

[0053] (Tetracarboxylic acid dianhydride) Examples of tetracarboxylic dianhydrides used in the synthesis of polyamic acid [A] include aliphatic tetracarboxylic dianhydrides and aromatic tetracarboxylic dianhydrides. Examples of aliphatic tetracarboxylic dianhydrides include linear tetracarboxylic dianhydrides and alicyclic tetracarboxylic dianhydrides.

[0054] Specific examples of these include linear tetracarboxylic dianhydrides such as 1,2,3,4-butanetetracarboxylic dianhydride and ethylenediaminetetraacetic acid dianhydride. Examples of alicyclic tetracarboxylic dianhydrides include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, substituted cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 5-(2,5-dioxotetrahydrofuran-3-yl)-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 5-(2,5-dioxotetrahydrofuran-3-yl)-8-methyl-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 2,4,6,8-tetracarboxybicyclo[3.3.0]octane-2:4,6:8-dianhydride, cyclopentanetetracarboxylic dianhydride, cyclohexanetetracarboxylic dianhydride, and 3,5,6-tricarboxy-2-carboxymethylnorbornane-2:3,5:6-dianhydride.

[0055] Examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, ethylene glycol bisanhydrotrimate, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 4,4'-carbonyldiphthalic anhydride, and 3,3',4,4'-biphenyltetracarboxylic dianhydride. Furthermore, the tetracarboxylic dianhydride described in Japanese Patent Publication No. 2010-97188 can be used as the tetracarboxylic dianhydride for the synthesis of polyamic acid [A]. The tetracarboxylic dianhydride can be used individually or in combination of two or more types.

[0056] The tetracarboxylic dianhydride used in the synthesis of polyamic acid [A] (and consequently polymer [A]) preferably contains an aliphatic tetracarboxylic dianhydride, and more preferably contains an alicyclic tetracarboxylic dianhydride, in that it has high solubility and can produce a liquid crystal alignment film that exhibits good liquid crystal alignment and electrical properties. The proportion of structural units derived from aliphatic tetracarboxylic dianhydride in polymer [A] is preferably 20 mol% or more, more preferably 40 mol% or more, and even more preferably 50 mol% or more, based on the total amount of structural units derived from tetracarboxylic dianhydride in polymer [A].

[0057] In order to obtain a polymer with excellent photo-orientation properties, and to reduce the occurrence of bright spots even after photo-orientation treatment by using it in combination with a specific diamine, polymer [A] is preferably composed of structural units derived from substituted cyclobutanetetracarboxylic dianhydride. Specifically, polymer [A] is preferably composed of structural units having a substructure represented by the following formula (4). [ka] (In formula (4), R 11 , R 12 , R 13 and R 14 Each of these is independently a hydrogen atom or a substituent. However, R 11 , R 12 , R 13 and R 14 One or more of these are substituents. (* represents a bond.)

[0058] In equation (4), R 11 , R 12 , R 13 and R 14 The substituents represented by (i.e., substituents on substituted cyclobutanetetracarboxylic dianhydride) include C1-C6 alkyl groups, C1-C6 halogenated alkyl groups, C1-C6 alkoxy groups, C1-C6 halogenated alkoxy groups, halogen atoms, etc. Of these, R 11 , R 12 , R 13and R 14 The substituent represented by is preferably a C1-C3 alkyl group, a C1-C3 halogenated alkyl group, a C1-C3 alkoxy group, a C1-C3 halogenated alkoxy group, or a halogen atom, more preferably a C1-C3 alkyl group, a C1-C3 fluoroalkyl group, or a fluorine atom, and particularly preferably a methyl group.

[0059] Specific examples of tetracarboxylic dianhydrides having a substructure represented by formula (4) include 1-methyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3-trimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1-ethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-diethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, and 1-ethyl-3-methyl-1,2,3,4-cyclobutane Examples include tetracarboxylic dianhydride, 1,3-dimethoxy-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-diethoxy-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1-trifluoromethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-di(trifluoromethyl)-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-di(trifluoromethoxy)-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3-tri(trifluoromethyl)-1,2,3,4-cyclobutanetetracarboxylic dianhydride, and 1,2,3,4-tetra(trifluoromethyl)-1,2,3,4-cyclobutanetetracarboxylic dianhydride.

[0060] When polymer [A] contains structural units derived from substituted cyclotetracarboxylic dianhydrides, the proportion of structural units derived from substituted cyclotetracarboxylic dianhydrides is preferably 20 mol% or more, more preferably 40 mol% or more, and even more preferably 60 mol% or more, relative to the total amount of structural units derived from tetracarboxylic dianhydrides in polymer [A].

[0061] (Diamine compounds) The diamine compounds used in the synthesis of polyamic acid [A] may consist solely of specific diamines, but may also be used in combination with diamines that do not have substructure (a) (hereinafter also referred to as "other diamines"). Examples of other diamines include aliphatic diamines, aromatic diamines, and diaminoorganosiloxanes. Examples of aliphatic diamines include linear diamines and alicyclic diamines.

[0062] Other specific examples of diamines include, as chain-type diamines, metaxylylenediamine and hexamethylenediamine; as alicyclic diamines, 1,4-diaminocyclohexane and 4,4'-methylenebis(cyclohexylamine); and as aromatic diamines, p-phenylenediamine, 1,4-diamino-2,5-dimethylbenzene, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, and 4- Aminophenyl-4-aminobenzoate, 4,4'-diaminoazobenzene, 3,5-diaminobenzoic acid, 1,5-bis(4-aminophenoxy)pentane, 1,2-bis(4-aminophenoxy)ethane, 1,3-bis(4-aminophenoxy)propane, 1,6-bis(4-aminophenoxy)hexane, 6,6'-(pentamethylenedioxy)bis(3-aminopyridine), N,N'-di(5-amino-2-pyridin (Lu)-N,N'-di(tert-butoxycarbonyl)ethylenediamine, bis[2-(4-aminophenyl)ethyl]hexanediic acid, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylamine, 4,4'-diaminodiphenethylurea, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 1,4-bis(4-aminophenyl) Phenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 4,4'-(phenylenediisopropylidene)bisaniline, 2,6-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, 3,6-diaminoacrididine, diphenylamine structure-containing monomer, formula (D-1) [ka] (In formula (D-1), R 21 and R 22 These are each an alkanediyl group, independently of each other. 23 R is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a thermally desorbed group. n1 is an integer from 1 to 3. If n1 is 2 or 3, there are multiple R 22 They are either identical or different from each other, and multiple R 23They are either identical or different from one another. Main-chain diamines such as compounds represented by the symbols; Hexadecanoxy-2,4-diaminobenzene, Octadecanoxy-2,4-diaminobenzene, Octadecanoxy-2,5-diaminobenzene, Cholestanyloxy-3,5-diaminobenzene, Cholesteryloxy-3,5-diaminobenzene, Cholestanyloxy-2,4-diaminobenzene, Cholesteryloxy-2,4-diaminobenzene, Cholestanyl 3,5-diaminobenzoate, Cholesteryl 3,5-diaminobenzoate , 3,5-Lanostanyl diaminobenzoate, 3,6-Bis(4-aminobenzoyloxy)cholestane, 3,6-Bis(4-aminophenoxy)cholestane, 4-(4'-Trifluoromethoxybenzoyloxy)cyclohexyl-3,5-diaminobenzoate, 1,1-Bis(4-((aminophenyl)methyl)phenyl)-4-butylcyclohexane, 3,5-diaminobenzoate=5ξ-cholestane-3-yl, formula (E-1) [ka] (In formula (E-1), X I and X II These are, independently, a single bond, -O-, *-COO-, or *-OCO- (where "*" indicates a bond with the diaminophenyl group). I This is an alkanediyl group with 1 to 3 carbon atoms. II R is a single bond or an alkanediyl group having 1 to 3 carbon atoms. III (where a is an alkyl group, alkoxy group, fluoroalkyl group, or fluoroalkoxy group having 1 to 20 carbon atoms. a is 0 or 1. b is an integer between 0 and 3. c is an integer between 0 and 2. d is 0 or 1. However, 1 ≤ a + b + c ≤ 3.) Side-chain diamines such as compounds represented by, Examples of diaminoorganosiloxanes include 1,3-bis(3-aminopropyl)-tetramethyldisiloxane.

[0063] Examples of compounds represented by formula (D-1) include those represented by formulas (D-1-1) to (D-1-3) below. Examples of compounds represented by formula (E-1) include those represented by formulas (E-1-1) to (E-1-4) below. Other diamines can be used individually or in combination of two or more. [ka]

[0064] In polyamic acid [A], the proportion of structural units derived from specific diamines is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, relative to the total amount of structural units derived from diamine compounds in polyamic acid [A], from the viewpoint of sufficiently improving the liquid crystal alignment properties, adhesion, and keystroke durability of the liquid crystal alignment film, and sufficiently suppressing the generation of bright spots in the liquid crystal element. One specific diamine may be used alone, or two or more may be used in combination.

[0065] • Synthesis of polyamic acids Polyamic acid [A] can be obtained by reacting a tetracarboxylic dianhydride with a diamine compound, along with a molecular weight modifier as needed. In the synthesis reaction of polyamic acid [A], the ratio of tetracarboxylic dianhydride to diamine compound used is preferably such that the acid anhydride groups of the tetracarboxylic dianhydride are 0.2 to 2 equivalents per 1 equivalent of amino groups of the diamine compound. Examples of molecular weight modifiers include acid monoanhydrides such as maleic anhydride, phthalic anhydride, and itaconic anhydride; monoamine compounds such as aniline, cyclohexylamine, and n-butylamine; and monoisocyanate compounds such as phenyl isocyanate and naphthyl isocyanate. The ratio of molecular weight modifier used is preferably 20 parts by mass or less per 100 parts by mass of the total amount of tetracarboxylic dianhydride and diamine compound used.

[0066] The synthesis reaction of polyamic acid [A] is preferably carried out in an organic solvent. The reaction temperature is preferably -20°C to 150°C, and the reaction time is preferably 0.1 to 24 hours. Examples of organic solvents used in the reaction include aprotic polar solvents, phenolic solvents, alcoholic solvents, ketone solvents, esteric solvents, etheric solvents, halogenated hydrocarbons, and hydrocarbons. Specific examples include using one or more selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide, m-cresol, xylenol, and halogenated phenol as the reaction solvent, or using a mixture of one or more of these with another organic solvent (e.g., butyl cellosolve, diethylene glycol diethyl ether, etc.). The amount of organic solvent used is preferably such that the total amount of tetracarboxylic dianhydride and diamine is 0.1 to 50% by mass of the total amount of the reaction solution.

[0067] The above reaction yields a polymer solution in which polyamic acid [A] is dissolved. This polymer solution may be used directly to prepare the liquid crystal alignment agent, or the polyamic acid [A] contained in the polymer solution may be isolated before being used to prepare the liquid crystal alignment agent.

[0068] • Polyamic acid esters When polymer [A] is a polyamic acid ester, the polyamic acid ester (hereinafter also referred to as "polyamic acid ester [A]") can be obtained, for example, by [I] reacting polyamic acid [A] with an esterifying agent, [II] reacting a tetracarboxylic acid diester with a diamine compound containing a specific diamine, or [III] reacting a tetracarboxylic acid diester dihalide with a diamine compound containing a specific diamine. Polyamic acid ester [A] may have only an amic acid ester structure, or it may be a partially esterified product in which both an amic acid structure and an amic acid ester structure coexist. The reaction solution obtained by dissolving polyamic acid ester [A] may be used as is for the preparation of the liquid crystal alignment agent, or the polyamic acid ester [A] contained in the reaction solution may be isolated before being used for the preparation of the liquid crystal alignment agent.

[0069] Polyimide When polymer [A] is a polyimide, the polyimide (hereinafter also referred to as "polyimide [A]") can be obtained, for example, by dehydrating and cyclizing a polyamic acid [A] synthesized as described above to imide it. Polyimide [A] may be a fully imidized product obtained by dehydrating and cyclizing all of the amic acid structure that the precursor polyamic acid [A] had, or it may be a partially imidized product in which only a part of the amic acid structure is dehydrated and cyclized, and the amic acid structure and imide ring structure coexist. The imidization rate of polyimide [A] is preferably 20 to 99%, and more preferably 30 to 90%. The imidization rate is expressed as a percentage of the ratio of the number of imide ring structures to the total number of amic acid structures and imide ring structures of the polyimide. Here, part of the imide ring may be an isoimide ring.

[0070] Dehydration and ring closure of polyamic acid [A] is preferably carried out by dissolving polyamic acid [A] in an organic solvent, adding a dehydrating agent and a dehydration and ring closure catalyst to the solution, and heating as necessary. In this method, acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride can be used as the dehydrating agent. The amount of dehydrating agent used is preferably 0.01 to 20 moles per mole of the amic acid structure of polyamic acid [A]. Tertiary amines such as pyridine, colidine, lutidine, and triethylamine can be used as the dehydration and ring closure catalyst. The amount of dehydration and ring closure catalyst used is preferably 0.01 to 10 moles per mole of the dehydrating agent used. Examples of organic solvents used in the dehydration and ring closure reaction include those exemplified for use in the synthesis of polyamic acid [A]. The reaction temperature for the dehydration and ring closure reaction is preferably 0 to 180°C. The reaction time is preferably 1.0 to 120 hours. The reaction solution containing polyimide[A] may be used directly to prepare the liquid crystal alignment agent, or the polyimide[A] may be isolated before being used to prepare the liquid crystal alignment agent.

[0071] Polyimide [A] is particularly preferred as the polymer [A] because it can increase the mechanical strength of the liquid crystal alignment film. According to the inventors' research, when polyamic acid is imidized, there is a tendency for the mechanical strength and adhesion of the liquid crystal alignment film to decrease. On the other hand, polyimide has lower solubility than polyamic acid, raising concerns about poor coating properties and film non-uniformity. In this regard, polyimide [A] having substructure (a) exhibits good solubility, making it possible to form a liquid crystal alignment film with high mechanical strength while suppressing a decrease in coating properties and film uniformity.

[0072] The solution viscosity of polymer [A] used in the preparation of the liquid crystal alignment agent is preferably 10 to 800 mPa·s when the solution is 10% by mass, and more preferably 15 to 500 mPa·s. The solution viscosity (mPa·s) is the value measured at 25°C using an E-type rotational viscometer for a 10% by mass polymer solution prepared using a good solvent for polymer [A] (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

[0073] The weight-average molecular weight (Mw) of polymer [A], measured by gel permeation chromatography (GPC), is preferably 1,000 to 500,000, and more preferably 2,000 to 300,000. Furthermore, the molecular weight distribution (Mw / Mn), expressed as the ratio of Mw to the number-average molecular weight (Mn) measured by GPC, is preferably 7 or less, and more preferably 5 or less. In preparing the liquid crystal alignment agent, polymer [A] may be used alone or in combination of two or more types.

[0074] <Other ingredients> The liquid crystal alignment agent may contain, in addition to polymer [A], components other than polymer [A] (hereinafter also referred to as "other components") as needed.

[0075] ·Polymer [B] The liquid crystal alignment agent of this disclosure may further contain a polymer component that does not have a substructure (a) (hereinafter also referred to as "polymer [B]"). The main skeleton of polymer [B] is not particularly limited. Examples of other polymers include polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane, polyester, polyenamine, polyurea, polyamide, polyamideimide, polybenzoxazole precursor, polybenzoxazole, cellulose derivative, polyacetal, (meth)acrylic polymer, styrene polymer, maleimide polymer, styrene-maleimide copolymer, etc. From the viewpoint of obtaining a highly reliable liquid crystal element, polymer [B] is preferably at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane, and polymers containing structural units derived from monomers having polymerizable unsaturated carbon-carbon bonds. Polymers containing structural units derived from monomers having polymerizable unsaturated carbon-carbon bonds include (meth)acrylic polymers, styrene polymers, maleimide polymers, and styrene-maleimide copolymers.

[0076] When polymer [B] is included in the liquid crystal alignment agent, the content of polymer [B] is preferably 1% by mass or more, and more preferably 2% by mass or more, relative to the total amount of polymer [A] and polymer [B]. Furthermore, the content of polymer [B] is preferably 95% by mass or less, and more preferably 90% by mass or less, relative to the total amount of polymer [A] and polymer [B]. Polymer [B] can be used alone or in combination of two or more types.

[0077] ·solvent The liquid crystal alignment agent of this disclosure is prepared as a liquid composition comprising a polymer [A] and other components used as needed, preferably dispersed or dissolved in a suitable solvent.

[0078] Organic solvents are preferred as solvents. Specific examples include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,2-dimethyl-2-imidazolidinone, 1,3-dimethyl-2-imidazolidinone, phenol, γ-butyrolactone, γ-butyrolactam, N,N-dimethylformamide, N,N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone, diacetone alcohol, 1-hexanol, 2-hexanol, propane-1,2-diol, 3-methoxy-1-butanol, ethylene glycol monomethyl ether, methyl lactate, ethyl lactate, butyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl acetoacetate, ethyl acetoethyl acetate, ethyl propionate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, and ethylene glycol-i-propyl ether. Examples of solvents include ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisopentyl ether, ethylene carbonate, propylene carbonate, propylene glycol monomethyl ether (PGME), diethylene glycol diethyl ether acetate, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol diacetate, cyclopentanone, and cyclohexanone. As solvents, one type can be used alone or two or more types can be used in combination.

[0079] Other components contained in the liquid crystal alignment agent include, in addition to those mentioned above, crosslinking agents, antioxidants, metal chelating compounds, curing accelerators, surfactants, fillers, dispersants, photosensitizers, and the like. The proportion of these other components can be appropriately selected for each compound, as long as it does not impair the effects of this disclosure.

[0080] The solid content concentration in the liquid crystal alignment agent (the ratio of the total mass of components other than the solvent to the total mass of the liquid crystal alignment agent) is appropriately selected considering viscosity, volatility, etc. The solid content concentration of the liquid crystal alignment agent is preferably in the range of 1 to 10% by mass. A solid content concentration of 1% by mass or more is preferable because it allows for sufficient film thickness of the coating and enables the production of a liquid crystal alignment film exhibiting better liquid crystal alignment properties. On the other hand, a solid content concentration of 10% by mass or less allows for a coating film of appropriate thickness, making it easier to obtain a liquid crystal alignment film exhibiting good liquid crystal alignment properties, and the viscosity of the liquid crystal alignment agent tends to be appropriate, resulting in good coatability.

[0081] ≪Liquid crystal alignment film and method for manufacturing the same≫ The liquid crystal alignment film of this disclosure is manufactured using a liquid crystal alignment agent prepared as described above. Preferably, the liquid crystal alignment film of this disclosure is manufactured by a method comprising the steps of forming a coating film with a liquid crystal alignment agent containing polymer [A] (coating film formation step) and irradiating the coating film with light to impart liquid crystal alignment ability (photo-alignment treatment step).

[0082] ·Coating film formation process In the manufacturing of a liquid crystal alignment film, first, a liquid crystal alignment agent is applied to a substrate, and preferably the applied surface is heated to form a coating on the substrate. As the substrate, for example, glass such as float glass or soda glass; or transparent substrates made of plastics such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, or poly(alicyclic olefin) can be used.

[0083] The method for applying the liquid crystal alignment agent to the substrate is not particularly limited. The liquid crystal alignment agent can be applied to the substrate by, for example, a spin coating method, a printing method (e.g., offset printing method, flexographic printing method, etc.), an inkjet method, a slit coating method, a bar coater method, an extrusion die method, a direct gravure coater method, a chamber doctor coater method, an offset gravure coater method, an impregnation coater method, an MB coater method, etc.

[0084] After applying the liquid crystal alignment agent, preheating (pre-bake) is preferably performed to prevent dripping of the applied liquid crystal alignment agent. The pre-bake temperature is preferably 30 to 200°C, and the pre-bake time is preferably 0.25 to 10 minutes. After that, a firing (post-bake) step is performed to completely remove the solvent and, if necessary, to thermally imide the amic acid structure present in the polymer. The firing temperature (post-bake temperature) at this time is preferably 80 to 280°C, more preferably 80 to 250°C. The post-bake time is preferably 5 to 200 minutes. The film thickness of the formed film is preferably 0.001 to 1 μm.

[0085] ·Photo alignment process Next, the coating film formed by the above process is subjected to a photo-alignment treatment in which light irradiation (radiation irradiation) is applied to the coating film to impart liquid crystal alignment ability. This yields a photo-aligned film. Light irradiation for photo-alignment can be performed by methods such as irradiating the coating film after the post-bake process, irradiating the coating film after the pre-bake process but before the post-bake process, or irradiating the coating film while it is being heated in either the pre-bake process or the post-bake process, or both.

[0086] As radiation to irradiate the coating film, for example, ultraviolet light and visible light including wavelengths of 150 to 800 nm can be used. Preferably, ultraviolet light including wavelengths of 200 to 400 nm is used. If the radiation is polarized, it may be linearly polarized or partially polarized. If the radiation used is linearly polarized or partially polarized, irradiation may be performed from a direction perpendicular to the substrate surface, from an oblique direction, or a combination of these. In the case of unpolarized radiation, the irradiation direction should be oblique.

[0087] Examples of light sources that can be used include low-pressure mercury lamps, high-pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonance lamps, xenon lamps, and excimer lasers. The radiation dose is preferably 200 to 30,000 J / m². 2 And more preferably, 500~10,000 J / m 2 In addition, after light irradiation to impart orientation ability, the substrate surface may be washed with, for example, water, an organic solvent (e.g., methanol, isopropyl alcohol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, etc.), or a mixture thereof, or the substrate may be heated.

[0088] ≪Liquid Crystal Elements≫ The liquid crystal element of this disclosure comprises a liquid crystal alignment film formed using the liquid crystal alignment agent described above. The liquid crystal driving method in the liquid crystal element is not particularly limited and can be applied to various modes such as TN type, STN type, VA type (including VA-MVA type, VA-PVA type, etc.), IPS (In Plane Switching) type, FFS (Fringe Field Switching) type, OCB (Optically Compensated Bend) type, and PSA type (Polymer Sustained Alignment). The liquid crystal element can be manufactured, for example, by a method including the coating film formation step and photo-alignment treatment step described above, as well as the cell construction step described below.

[0089] The substrate used in the coating film formation process varies depending on the desired operating mode. For example, when manufacturing TN, STN, or VA type liquid crystal elements, two substrates with patterned transparent conductive films are used. When manufacturing IPS or FFS type liquid crystal elements, one substrate with comb-shaped patterned electrodes and a counter substrate without electrodes are used. As the transparent conductive film, NESA film (registered trademark of PPG, Inc., USA) made of tin oxide (SnO2), ITO film made of indium oxide-tin oxide (In2O3-SnO2), etc., can be used.

[0090] • Cell construction process In the cell construction process, two substrates on which a liquid crystal alignment film has been formed by the above-described photo-alignment process are prepared, and a liquid crystal cell is manufactured by placing liquid crystal between the two substrates facing each other. Methods for manufacturing a liquid crystal cell include, for example, placing two substrates facing each other with a gap in between so that the liquid crystal alignment films face each other, bonding the periphery of the two substrates with a sealant, injecting and filling the cell gap surrounded by the substrate surface and the sealant, and sealing the injection hole, or the ODF method. As the sealant, for example, an epoxy resin containing a curing agent and aluminum oxide spheres as spacers can be used.

[0091] Either positive or negative liquid crystals may be used. In IPS and FFS type liquid crystal elements, the use of negative liquid crystals is preferable because it can reduce transmission loss above the electrodes and improve contrast. Furthermore, in photodegradable liquid crystal alignment films in which anisotropy is imparted to the film by decomposition of polymers by light irradiation, when liquid crystal elements are fabricated using negative liquid crystals, there is a tendency for a high incidence of display defects (bright spots) caused by decomposition products of the polymer generated by radiation irradiation. In contrast, with the liquid crystal alignment agent of this disclosure, high-quality liquid crystal elements with suppressed bright spot generation can be obtained. Examples of liquid crystals include nematic liquid crystals and smectic liquid crystals, with nematic liquid crystals being preferred.

[0092] When manufacturing liquid crystal display devices, a polarizing plate is then bonded to the outer surface of the liquid crystal cell. Examples of polarizing plates include a polarizing film called an "H film," which is made by stretching and oriented polyvinyl alcohol while absorbing iodine, sandwiched between cellulose acetate protective films, or a polarizing plate made of the H film itself.

[0093] The liquid crystal elements of this disclosure can be effectively applied to a variety of uses. Specifically, they can be used, for example, in various display devices such as watches, portable game consoles, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, liquid crystal televisions, information displays, as well as in dimming devices, phase difference films, and the like.

[0094] According to the disclosure described above, the following means are provided.

[0095] [Method 1] A method for producing a liquid crystal alignment film, comprising the steps of: forming a coating film with a liquid crystal alignment agent containing a polymer [A] having a partial structure (a) represented by the above formula (1); and irradiating the coating film with light to impart liquid crystal alignment ability. [Method 2] The method for producing a liquid crystal alignment film according to [Method 1], wherein the polymer [A] has structural units derived from the compound represented by formula (2) above. [Method 3] The method for producing a liquid crystal alignment film according to [Method 1] or [Method 2], wherein the polymer [A] is at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide. [Method 4] A method for producing a liquid crystal alignment film according to any one of [Method 1] to [Method 3], wherein the polymer [A] has structural units derived from an aliphatic tetracarboxylic dianhydride. [Method 5] The method for producing a liquid crystal alignment film according to [Method 4], wherein the aliphatic tetracarboxylic dianhydride has a substructure represented by formula (4) above. [Method 6] A method for producing a liquid crystal alignment film according to any one of [Method 1] to [Method 5], further comprising a polymer [B] that does not have the substructure (a). [Method 7] The method for producing a liquid crystal alignment film according to [Method 6], wherein the polymer [B] is at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide. [Method 8] A photo-orienting agent containing a polymer [A] having a substructure (a) represented by the above formula (1). [Method 9] A liquid crystal element comprising a liquid crystal alignment film manufactured by any of the methods described in [Method 1] to [Method 7]. [Method 10] A polymer containing a structural unit derived from a diamine represented by the above formula (3). [Method 11] A diamine represented by the above formula (3). [Examples]

[0096] The embodiments will be described in more detail below based on the examples, but the present invention is not to be interpreted as being limited by the following embodiments.

[0097] In the following example, the imidization rate of polyimide in the polymer solution was measured by the following method. [Imidification rate of polyimides] A polyimide solution was added to pure water, and the resulting precipitate was thoroughly dried under reduced pressure at room temperature. Then it was dissolved in deuterated dimethyl sulfoxide, with tetramethylsilane as the reference material, at room temperature. 1 1H-NMR measurements were performed. 1 The imidization rate [%] was determined from the 1H-NMR spectrum using the following formula (I). Imidization rate [%] = (1 - (A 1 / ( A 2 ×α)))×100 …(I) (In formula (I), A 1 This represents the peak area originating from the proton of the NH group, appearing around a chemical shift of 10 ppm. 2 α represents the peak area derived from other protons, and α is the ratio of other protons to one proton of the NH group in the polymer precursor (polyamic acid).

[0098] The abbreviations for the compounds are as follows. In the following, the compound represented by formula (X) (where X is a symbol) may simply be referred to as "compound (X)".

[0099] (Tetracarboxylic acid dianhydride) [ka]

[0100] (Diamine compounds) [ka] [ka]

[0101] <Synthesis of monomers> [Synthesis Example 1A] Compound (DA-1) was synthesized according to the following scheme. [ka]

[0102] In a three-necked flask equipped with a reflux condenser and a nitrogen inlet tube, 4-nitroguaiacol (23.72 g), 1,2-bis(tosyloxy)ethane (25.34 g), and potassium carbonate (23.63 g) were placed and the flask was purged with nitrogen. 130 mL of dimethylformamide was added, and the temperature was gradually raised to 80°C and stirred for 6 hours. After the reaction was complete, 650 mL of pure water was added to the reaction solution and stirred for 1 hour. The precipitated crystals were filtered under reduced pressure, the crude product was washed with water and 2-propanol, and vacuum-dried to obtain a powdered dinitro intermediate product (23.25 g, yield 93%). Next, 23.25 g of the dinitro intermediate and 408 mg of palladium carbon were placed in a three-necked flask equipped with a reflux condenser and a nitrogen inlet tube, and the flask was purged with nitrogen. 65 mL of tetrahydrofuran degassed by nitrogen bubbling and 65 mL of ethanol were added, and the mixture was stirred while cooling to 5°C to form a suspension. 18.5 mL of hydrazine monohydrate was slowly added dropwise to the suspension. After addition, the temperature was gradually increased to 60°C and the mixture was stirred for 4 hours. The reaction solution was diluted with tetrahydrofuran, filtered by Celite filtration, and then concentrated to precipitate the product. The precipitate was washed with THF, and the crystals were filtered under reduced pressure. The obtained crystals were washed with water and 2-propanol, and vacuum-dried to obtain the yellowish-brown solid compound (DA-1) (16.04 g, yield 79%). Its structure is represented by the nuclear magnetic resonance spectrum of the intramolecular hydrogen atom. 1 Confirmation was made using 1H-NMR spectroscopy. The measurement data is shown below. 1 H-NMR (400MHz, [D6]-DMSO) δ: 6.67 (dd, 2H), 6.26 (d, 2H), 6.04 (dd, 2H), 4.70 (s, 4H), 4.01 (s, 4H), 3.66 (s, 6H).

[0103] <Synthesis of polymers> 1. Synthesis of polyamic acids [Synthesis Example 1] 100 moles of compound (TA-1) as a tetracarboxylic dianhydride, 40 moles of compound (DA-1), 40 moles of compound (DB-5), and 20 moles of compound (DB-8) as diamine compounds were dissolved in N-methyl-2-pyrrolidone (NMP), and the reaction was carried out at room temperature for 6 hours to obtain a solution containing 15% by mass of polyamic acid (referred to as polymer (PA-1)).

[0104] [Synthesis Examples 2-9] Except for changing the types and amounts of tetracarboxylic dianhydride and diamine compounds used as shown in Tables 1 and 2, the same procedure as in Synthesis Example 1 was performed to obtain a solution containing 15% by mass of polyamic acid (polymers (PA-2) to (PA-9)).

[0105] [Table 1]

[0106] [Table 2]

[0107] 2. Synthesis of polyimides [Synthesis Example 10] 90 moles of compound (TA-1) and 10 moles of compound (TA-2) as tetracarboxylic dianhydrides, and 100 moles of compound (DA-1) as a diamine compound were dissolved in N-methyl-2-pyrrolidone (NMP), and the reaction was carried out at room temperature for 6 hours to obtain a solution containing 15% by mass of polyamic acid. Next, NMP was added to the obtained polyamic acid solution to make a 10% by mass solution of polyamic acid, and pyridine and acetic anhydride were added to carry out a dehydration and cyclization reaction at 60°C for 4 hours. After the dehydration and cyclization reaction, the solvent in the system was replaced with fresh NMP to obtain a solution containing 15% by mass of polyimide (referred to as polymer (PI-1)) with an imidization rate of approximately 90%.

[0108] [Synthesis Examples 11-20] By changing the types and amounts of tetracarboxylic dianhydride and diamine compounds used as shown in Table 3, and adjusting the amounts of pyridine and acetic anhydride, the imidization rate was synthesized as shown in Table 3, thereby obtaining a solution containing 15% by mass of polyimide (polymers (PI-2) to (PI-11)).

[0109] [Table 3]

[0110] <Preparation and evaluation of liquid crystal alignment agents> [Example 1] 1. Preparation of liquid crystal alignment agent A solution of polymer (PA-1) obtained in Synthesis Example 1 and a solution of polymer (PA-3) obtained in Synthesis Example 3 were mixed so that polymer (PA-1) and polymer (PA-3) were in a solid content ratio of (PA-1) / (PA-3) = 30 / 70 (mass ratio). The mixture was then diluted with NMP and butyl cellosolve (BC) to obtain a solution with a solvent composition of NMP / BC = 80 / 20 (mass ratio) and a solid content concentration of 3.5% by mass. Liquid crystal alignment agent (AL-1) was prepared by filtering this solution through a pore size filter of 0.2 μm.

[0111] 2. Manufacturing of FFS-type liquid crystal display elements using the photo-alignment method A glass substrate (referred to as the first substrate) was prepared, on which a flat electrode (bottom electrode), an insulating layer, and a comb-shaped electrode (top electrode) were laminated in that order on one side, and a glass substrate (referred to as the second substrate) without electrodes was prepared. Next, a liquid crystal alignment agent (AL-1) was applied to the electrode-forming surface of the first substrate and one side of the second substrate using a spinner, and heated on an 80°C hot plate for 1 minute (pre-bake). After that, it was dried in a 150°C oven with nitrogen purged for 30 minutes (post-bake) to form a coating film with an average thickness of 0.1 μm. The obtained coating film was exposed to 1,000 J / m of ultraviolet light containing linearly polarized 254 nm emission lines using an Hg-Xe lamp. 2 The substrate was irradiated from the direction normal to the substrate to perform photoalignment treatment. The irradiation dose was measured using a light meter that measures at a wavelength of 254 nm. Next, the photoaligned coating was heat-treated by heating it in a clean oven at 150°C for 30 minutes to form a liquid crystal alignment film. Next, on one of the pair of substrates on which the liquid crystal alignment film was formed, an epoxy resin adhesive containing aluminum oxide spheres with a diameter of 3.5 μm was screen printed onto the outer edge of the surface with the liquid crystal alignment film. Then, the substrates were stacked and pressed together so that the projection direction of the polarization axis onto the substrate surface during light irradiation was antiparallel, and the adhesive was heat-cured at 150°C for 1 hour. Subsequently, negative liquid crystal (Merck, MLC-6608) was filled between the pair of substrates through the liquid crystal injection port, and the liquid crystal injection port was sealed with epoxy adhesive to obtain a liquid crystal cell. Furthermore, to remove the flow orientation during liquid crystal injection, it was heated at 120°C and then slowly cooled to room temperature. After that, polarizing plates were bonded to both outer surfaces of the substrate in the liquid crystal cell to obtain a liquid crystal display element. The above series of operations was performed with a post-bake UV irradiation dose of 100 to 10,000 J / m². 2 By modifying each element within the specified range, we manufactured three or more liquid crystal display elements with different UV irradiation levels. The liquid crystal display element exhibiting the best alignment characteristics (optimal exposure level) was used for the following evaluation.

[0112] 3. Evaluation of liquid crystal alignment properties The liquid crystal display element manufactured in step 2 above is used at 27,000 cd / m². 2 The liquid crystal alignment properties were evaluated by observing the rate of change α of retardation before and after backlight illumination, after leaving the samples undisturbed on a high-brightness backlight for 500 hours. Retardation was measured using an Axoscan from OptoScience, and the rate of change α of retardation before and after backlight illumination was calculated using the following formula (II). A smaller rate of change α indicates better liquid crystal alignment. A rate of change α of 0.5% or less was classified as "Excellent (◎)", a rate of change greater than 0.5% and 1% or less was classified as "Good (○)", a rate of change greater than 1% and 2% or less was classified as "Acceptable (△)", and a rate of change greater than 2% was classified as "Poor (×)". α = Δθ / θ¹ …(II) (In equation (II), Δθ represents the retardation difference before and after irradiation, and θ1 represents the retardation value before irradiation.) As a result, the liquid crystal alignment of this embodiment was rated as "good (○)".

[0113] 4. Evaluation of bright spots (bright spot suppression) in liquid crystal cells The liquid crystal cells manufactured in step 2 above were observed using a polarizing microscope (ECLIPSE E600WPOL) (Nikon Corporation) to evaluate the ability to suppress bright spots. Specifically, the liquid crystal cells were placed between two polarizing plates arranged so that their polarization axes were orthogonal, and the liquid crystal cells were observed with a polarizing microscope at 5x magnification (observation area: approximately 2500 μm × 2500 μm). The fewer the number of bright spots, the less decomposition products are produced due to the photo-alignment treatment, indicating a better result. If the number of bright spots was 100 or more, it was rated as "Poor (×)", if it was between 10 and 100, it was rated as "Acceptable (△)", and if it was less than 10, it was rated as "Good (○)". As a result, in this example, it was rated as "Good (○)".

[0114] 5. Evaluation of keystroke durability through keystroke testing The liquid crystal alignment of the liquid crystal display elements manufactured in step 2 above was evaluated after a keystroke test. The evaluation was performed as follows: A silicone rubber pen 3R (manufactured by Touch Panel Research Institute Co., Ltd.) with a tip radius of 3 mm was set in the keystroke section (solenoid type) of a keystroke test machine (manufactured by Touch Panel Research Institute Co., Ltd.), and the pen tip was positioned so that it was at the center of the liquid crystal display element. After 10,000 keystrokes with the silicone rubber pen at a load of 500 g and 10 Hz, the liquid crystal display element was observed under a microscope (100x magnification) and the number of bright spots was measured. The fewer the number of bright spots, the better the keystroke durability of the liquid crystal display element. If the number of bright spots was less than 30, it was judged as "Excellent (◎)", if it was 30 or more but less than 50, it was judged as "Good (○)", if it was 50 or more but less than 100, it was judged as "Acceptable (△)", and if it was 100 or more, it was judged as "Poor (×)". As a result, this example received a "Good (○)" rating.

[0115] 5. Evaluation of adhesion The liquid crystal alignment agent (AL-1) prepared in step 1 above was applied to a glass substrate using a spinner, pre-baked on an 80°C hot plate for 2 minutes, and then heated in a 230°C oven with nitrogen purging for 30 minutes (post-bake) to form a coating with an average thickness of 0.10 μm. Two glass substrates with the coating were prepared by repeating the same procedure. On the coating of one glass substrate, an ODF sealant (Sekisui Chemical Co., Ltd., S-WB42) was applied to a width of 1 mm, and the other glass substrate was bonded so that the coating and the ODF sealant were in contact. After that, a metal halide lamp was used to heat 30,000 J / m². 2 After irradiating with light (equivalent to 365 nm), the sample was heated in a 120°C oven for 1 hour. The adhesion of the film was then evaluated by measuring the adhesion force using a tensile and compression testing machine (Imada Seisakusho Co., Ltd., model number: SDWS-0201-100SL). The evaluated adhesion force was 175 N / cm². 2 If the result is above this, it is marked as "Good (○)", 125 N / cm 2 More than 175N / cm 2 If it is less than 125 N / cm², it is marked as "Acceptable (△)". 2 If the result was less than 175 N / cm², it was classified as "Poor (×)". As a result, in this embodiment, the adhesion force was 175 N / cm². 2 The adhesion was rated as "good (○)".

[0116] [Examples 2-12 and Comparative Examples 1-3] Liquid crystal alignment agents were prepared in the same manner as in Example 1, except that the composition of the liquid crystal alignment agent was changed as shown in Table 4. Furthermore, using the obtained liquid crystal alignment agent, FFS-type liquid crystal display elements were manufactured by the photo-alignment method in the same manner as in Example 1, and the liquid crystal alignment properties, bright spot suppression properties, keystroke durability, and adhesion properties were evaluated. The results are shown in Table 4. Note that two types of polymers were used as polymer components in Examples 2, 4, 6, 8-10, 12 and Comparative Examples 2 and 3, while three types of polymers were used as polymer components in Examples 5, 7, and 11. In Table 4, the values ​​in the polymer column represent the blending ratio (parts by mass) of each polymer in terms of solid content relative to 100 parts by mass of the total amount of polymer components used in the preparation of the liquid crystal alignment agent.

[0117] [Table 4]

[0118] As shown in Table 4, Examples 1 to 12, which used a liquid crystal alignment agent containing polymer [A], showed a better balance of liquid crystal alignment, bright spot suppression of liquid crystal cells, keystroke durability, and film adhesion compared to Comparative Examples 1 to 3, which used a liquid crystal alignment agent without polymer [A].

[0119] From these results, it has become clear that a liquid crystal alignment agent containing polymer [A] can be used to obtain a liquid crystal element that is excellent in liquid crystal alignment, keystroke durability and adhesion, and also exhibits less generation of bright spots in the liquid crystal cells.

Claims

1. A step of forming a coating film with a liquid crystal alignment agent containing a polymer [A] having a substructure (a) represented by the following formula (1), A step of irradiating the aforementioned coating film with light to impart liquid crystal alignment ability, A method for manufacturing a liquid crystal alignment film, including the above. 【Chemistry 1】 (In formula (1), A １ and A ２ are each independently a divalent aromatic ring group. However, one or both of A １ and A ２ has a structure in which a group represented by -OR １ , -NR ２ R ３ or -SR ４ is bonded to the aromatic ring. R １ , R ２ and R ４ are each independently a hydrogen atom or a monovalent organic group. R ３ is a monovalent organic group. B １ and B ２ are each independently -O-, -S- or -NR ５ -. R5 is a monovalent hydrocarbon group having 1 to 10 carbon atoms or a thermally desorbable group. X is a divalent hydrocarbon group. "*" represents a bond.)

2. The method for producing a liquid crystal alignment film according to claim 1, wherein the polymer [A] has structural units derived from a compound represented by the following formula (2). 【Chemistry 2】 (In formula (2), A １ A ２ , B １ , B ２ And X is equivalent to equation (1) above.

3. The method for producing a liquid crystal alignment film according to claim 1, wherein the polymer [A] is at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide.

4. The method for producing a liquid crystal alignment film according to claim 3, wherein the polymer [A] has structural units derived from an aliphatic tetracarboxylic dianhydride.

5. The method for producing a liquid crystal alignment film according to claim 4, wherein the aliphatic tetracarboxylic dianhydride has a substructure represented by the following formula (4). 【Transformation 3】 (In formula (4), R １１ , R １２ , R １３ and R １４ Each of these is independently a hydrogen atom or a substituent. However, R １１ , R １２ , R １３ and R １４ One or more of these are substituents. (* represents a bond.)

6. A method for producing a liquid crystal alignment film according to claim 1, further comprising a polymer [B] that does not have the aforementioned substructure (a).

7. The method for producing a liquid crystal alignment film according to claim 6, wherein the polymer [B] is at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide.

8. A photo-orienting agent containing a polymer [A] having a substructure (a) represented by the following formula (1). 【Chemistry 4】 (In formula (1), A １ and A ２ Each of these is an independent divalent aromatic ring group. However, A １ and A ２ One or both of are -OR １ , -NR ２ R ３ or -SR ４ It has a structure in which a group represented by is bonded to an aromatic ring. １ , R ２ and R ４ Each of these is independently a hydrogen atom or a monovalent organic group. ３ This is a monovalent organic group. １ and B ２ These are independently -O-, -S-, or -NR ５ - R5 is a monovalent hydrocarbon group or thermally desorbable group having 1 to 10 carbon atoms. X is a divalent hydrocarbon group. "*" indicates a bond.

9. A liquid crystal element comprising a liquid crystal alignment film manufactured with the photoalignment agent described in claim 8.

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