Manufacturing method of liquid crystal alignment film, photoaligning agent, liquid crystal element, polymer and diamine

Abstract

This invention provides a liquid crystal alignment agent that can produce a liquid crystal alignment film with excellent liquid crystal alignment properties, key durability, and adhesion, and can be used to manufacture liquid crystal elements with suppressed bright spot defects. The liquid crystal alignment film is manufactured by a method comprising the steps of forming a coating film using a liquid crystal alignment agent containing a polymer [A] having a partial structure (a) represented by formula (1); and the step of irradiating the coating film with light to impart liquid crystal alignment capability. In formula (1), A1 and A2 are divalent aromatic ring groups. One or both of A1 and A2 have a structure formed by a group bonded to an aromatic ring as represented by -OR1, -NR2R3, or -SR4. B1 and B2 are single bonds, -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-. X is a divalent hydrocarbon group.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a liquid crystal alignment film, a photoaligning agent, a liquid crystal element, a polymer, and a compound. Prior Technology

[0002] Liquid crystal elements (LCDs) are used in a wide range of applications, from relatively large display devices such as LCD TVs or information displays to small display devices such as smartphones. The performance of an LCD element is determined by various characteristics such as the alignment or pretilt angle of the liquid crystal and the voltage holding factor. To improve the performance of LCD elements, in addition to improvements to the liquid crystal material, improvements have been made to 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 polyamide and its derivatives as products of the reaction of tetracarboxylic dianhydride and diamine. The liquid crystal alignment agent contains polyamide obtained using di-tert-butyl{[hexamethylenedioxybis(azanediyl)]bis(5-amino-2,1-phenylene)}diaminocarbamate as the diamine. Patent Document 2 discloses a liquid crystal alignment agent containing polyimide obtained using 4,4'-[ethane-1,2-diylbis(oxy)]bis(3-methylaniline) as the diamine. [Existing Technical Documents] [Patent Literature]

[0004] [Patent Document 1] International Publication No. 2014 / 104015 [Patent Document 2] International Publication No. 2017 / 047596 Summary of the Invention

[0005] [The problem the invention aims to solve] As a method for forming liquid crystal alignment films by imparting anisotropy to the film, there is the photoalignment method. The photoalignment method involves irradiating a linearly induced organic thin film formed on a substrate with polarized or unpolarized radiation to impart anisotropy to the film, thereby controlling the alignment of liquid crystal molecules. According to this method, compared to conventional rubbing methods, the generation of dust or static electricity during the process can be suppressed, thus preventing display defects or yield reduction caused by dust, etc. Furthermore, it has the advantage of uniformly imparting liquid crystal alignment capability to the organic thin film formed on the substrate. On the other hand, when using the photoalignment method, polymer decomposition products such as polymers are easily generated by light irradiation, easily leading to display defects (bright spots) caused by these decomposition products. To achieve high-quality liquid crystal elements, it is required to have excellent liquid crystal alignment, one of the basic characteristics, while suppressing the generation of bright spots.

[0006] In mobile applications such as smartphones and personal computers (PCs), efforts are underway to achieve narrow bezels while further expanding the working area of ​​touch panels and miniaturizing display devices. One method for achieving narrow bezels is to form a liquid crystal alignment film on the entire substrate surface, then apply a sealant to the liquid crystal alignment film to bond the substrates together. However, when a sealant is applied to the liquid crystal alignment film, it is easy to apply force to the area where the sealant is applied. Therefore, if the mechanical properties or adhesion of the liquid crystal alignment film are low, there is a risk of the substrates peeling off.

[0007] Furthermore, in recent years, touch panels have become the mainstream in LCD components used in smartphones and automotive applications, making them susceptible to external forces caused by user button presses. From the perspective of improving the reliability of LCD components, the liquid crystal alignment film that constitutes the LCD component must also be resistant to degradation of display quality caused by external forces and have good button durability (also known as touch panel durability).

[0008] The present invention was made in view of the aforementioned problem, and its main objective is to provide a liquid crystal alignment agent that can produce a liquid crystal alignment film with excellent liquid crystal alignment properties, key durability and adhesion, and can manufacture a liquid crystal element in which the generation of bright spots is suppressed. [Technical means to solve the problem]

[0009] The present invention employs the following means to solve the aforementioned problem.

[0010] <1> A method for manufacturing a liquid crystal alignment film includes: a step of forming a coating film by means of a liquid crystal alignment 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 alignment capability. [Chemistry 1] (In formula (1), A1 and A2 are independently divalent aromatic ring groups; wherein, one or both of A1 and A2 have a structure formed by a group bond represented by -OR1, -NR2R3 or -SR4 bonded to an aromatic ring; R1, R2 and R4 are independently hydrogen atoms or monovalent organic groups; R3 is a monovalent organic group; B1 and B2 are independently single bonds, -O-, -S-, -NR5-, -CO-, *1-CO-O-, *1-O-CO-, *1-CS-O-, *1-O-CS-, *1-CO-NR6- or *1-NR6-CO-NR7-; "*1" indicates a bond with A1 or A2; R5, R6 and R 7 are either hydrogen atoms or monovalent organic groups; X is a divalent hydrocarbon group; "*" indicates a bond.

[0011] <2> A photoaligning agent comprising a polymer [A] having a partial structure (a) represented by the formula (1). <3> A liquid crystal element, comprising the means by the... <1> Liquid crystal alignment film manufactured by a method. <4> A polymer comprising structural units derived from a diamine represented by the following formula (3). [Chemistry 2] (In formula (3), A3 and A4 are independently divalent aromatic ring groups; wherein, one or both of A3 and A4 have a structure formed by a group bond represented by -OR1a or -NR2aR3a bonded to an aromatic ring; R1a and R2a are independently monovalent hydrocarbon groups; R3a is a hydrogen atom or a monovalent organic group; B3 and B4 are independently single bonds, -O-, -S-, -NR5a-, -CO-, *1-CO-O-, *1-O-CO-, *1-CS-O-, *1-O-CS-, *1-CO-NR6a- or *1-NR6a-CO-NR7a-; R5a is a monovalent organic group; R6a and R7a are independently hydrogen atoms or monovalent organic groups; "*1" indicates a group bonded to A3 or A4.) 4. When B3 is -O-, Y is an alkyldiyl, divalent alicyclic hydrocarbon, or divalent aromatic hydrocarbon with 1 or 2 carbons; when B3 is *1-O-CO-, Y is an alkyldiyl, divalent alicyclic hydrocarbon with an aliphatic ring having 4 or more carbons, or divalent aromatic hydrocarbon; when B3 is other than -O- and *1-O-CO-, Y is a divalent hydrocarbon. <5> A diamine, represented by the formula (3). [The effects of the invention]

[0012] Through this invention, a liquid crystal alignment film with excellent liquid crystal alignment, button durability and sealing can be obtained, and a liquid crystal element with suppressed bright spot defects can be obtained. Implementation

[0013] The following describes the manufacturing method of the liquid crystal alignment agent and liquid crystal alignment film disclosed herein.

[0014] Furthermore, in this specification, the term "hydrocarbon group" encompasses chain-like hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. "Chain-like hydrocarbon group" refers to a straight-chain hydrocarbon group or branched hydrocarbon group whose main chain does not contain a ring structure and is composed solely of a chain structure. Chain-like hydrocarbon groups can be saturated or unsaturated. "Alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic hydrocarbon structure as its ring structure and does not contain an aromatic ring structure. Alicyclic hydrocarbon groups do not necessarily need to consist solely of an alicyclic hydrocarbon structure; they may also include groups with a chain structure in a portion of their structure. "Aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as its ring structure. Aromatic hydrocarbon groups do not necessarily need to consist solely of an aromatic ring structure; they may also include a chain structure or an alicyclic hydrocarbon structure in a portion of their structure. "Aromatic ring" encompasses both aromatic hydrocarbon rings and aromatic heterocycles. "Organic group" refers to a group of atoms formed 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 disclosed herein contains a polymer [A] having a partial structure (a) represented by the following formula (1). [Chemistry 3] (In formula (1), A1 and A2 are independently divalent aromatic ring groups; wherein, one or both of A1 and A2 have a structure formed by a group bond represented by -OR1, -NR2R3 or -SR4 bonded to an aromatic ring; R1, R2 and R4 are independently hydrogen atoms or monovalent organic groups; R3 is a monovalent organic group; B1 and B2 are independently single bonds, -O-, -S-, -NR5-, -CO-, *1-CO-O-, *1-O-CO-, *1-CS-O-, *1-O-CS-, *1-CO-NR6- or *1-NR6-CO-NR7-; "*1" indicates a bond with A1 or A2; R5, R6 and R 7 are either hydrogen atoms or monovalent organic groups; X is a divalent hydrocarbon group; "*" indicates a bond.

[0016] The liquid crystal alignment agent disclosed herein is particularly suitable as a liquid crystal alignment agent (i.e., a photoalignment agent) for forming liquid crystal alignment films by photoalignment processing. Hereinafter, the components contained in the liquid crystal alignment agent of this disclosure, and other components that may be arbitrarily formulated as needed, will be described.

[0017] <Polymer[A]> Regarding part of the structure (a) In formula (1), the divalent aromatic ring groups represented by A1 and A2 can be categorized as divalent aromatic hydrocarbon groups and divalent aromatic heterocyclic groups. As a divalent aromatic hydrocarbon group, a group formed by removing any hydrogen atom bonded to a carbon atom of the constituting ring of a benzene ring, biphenyl ring, naphthalene ring, or anthracene ring can be listed. As a divalent nitrogen-containing aromatic heterocyclic group, a group formed by removing any hydrogen atom bonded to a carbon atom of the constituting ring of a pyridine ring, pyrimidine ring, pyridazine ring, or pyrazine ring can be listed. Among these, the divalent aromatic ring groups represented by A1 and A2 are preferably divalent aromatic hydrocarbon groups, and more preferably groups formed by removing any hydrogen atom bonded to a carbon atom of the constituting ring of a benzene ring.

[0018] One or both of A1 and A2 have an electron-donating group (hereinafter also referred to as "substituent F1") bonded to an aromatic ring, represented by -OR1, -NR2R3, or -SR4. By introducing a structure with substituent F1 directly bonded to the aromatic ring into the polymer, thermal rearrangement and liquid crystal alignment are improved. Alternatively, the introduction of substituent F1 can reduce crystallinity, resulting in a structure that easily mitigates stress, thereby suggesting improved strength and bond durability. Furthermore, the introduction of substituent F1 can improve the polymer's solubility and achieve higher polymer sensitivity.

[0019] From the viewpoint of fully achieving the improved alignment of the liquid crystal, the monovalent organic group represented by R1, R2, R3, or R4 is preferably a monovalent hydrocarbon group or a thermally detachable group having 1 to 10 carbon atoms, more preferably a monovalent hydrocarbon group or a thermally detachable group having 1 to 6 carbon atoms, and even more preferably a monovalent hydrocarbon group or a thermally detachable group having 1 to 5 carbon atoms. Furthermore, a thermally detachable group is a group that is detached by heat and replaced by a hydrogen atom. From the viewpoint of ensuring good thermal detachability and reducing the amount of detached portion remaining in the film, the thermally detachable group is preferably having 15 or fewer carbon atoms, more preferably 10 or fewer carbon atoms.

[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. Among these, monovalent hydrocarbon groups having 1 to 6 carbon atoms are preferred, alkyl 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] Specific examples of R1 being a thermally detachable group include: acetyl, benzoyl, benzyl, p-methoxyphenylbenzyl, methoxymethyl, tert-butoxycarbonyl, trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, triphenylmethyl, etc. Among these, the thermally detachable group represented by R1 is preferably acetyl, methoxymethyl, or tert-butoxycarbonyl, and more preferably acetyl or tert-butoxycarbonyl (Boc group).

[0022] Specific examples of thermally removable groups for R2 and R3 include: urethane-based protecting groups, amide-based protecting groups, amide-based protecting groups, amide-imine-based protecting groups, sulfonamide-based protecting groups, etc. Among these, urethane-based protecting groups are preferred in terms of high thermal removability. Specific examples include: tert-butoxycarbonyl, methoxycarbonyl, benzyloxycarbonyl, 1,1-dimethyl-2-haloethyloxycarbonyl, allyloxycarbonyl, 2-(trimethylsilyl)ethoxycarbonyl, 9-fluorenylmethyloxycarbonyl, etc. Among these, tert-butoxycarbonyl (Boc group) is particularly preferred in terms of excellent thermal removability and reduction of the amount of removable portion remaining in the membrane.

[0023] Specific examples of R4 being a thermally degradable group include: benzyloxymethyl, p-methoxybenzyloxymethyl, tert-butoxycarbonyl, trimethylsilyl, etc. Among these, tert-butoxycarbonyl (Boc group) is preferred.

[0024] From the viewpoint of achieving good liquid crystal alignment, R1, R2, and R4 are preferably hydrogen atoms, monovalent hydrocarbon groups with 1 to 6 carbon atoms, or thermally detachable groups, more preferably hydrogen atoms, alkyl groups with 1 to 3 carbon atoms, phenyl groups, or thermally detachable groups. R3 is preferably a monovalent hydrocarbon group with 1 to 6 carbon atoms or a thermally detachable group, more preferably an alkyl group with 1 to 3 carbon atoms, phenyl groups, or thermally detachable groups.

[0025] Specific examples of substituent F1 include: hydroxyl, alkoxy group with 1 to 5 carbon atoms, alkyl carbonyloxy group with 2 to 5 carbon atoms (acetoxy, propionic, etc.), tert-butoxycarbonyloxy group, alkyl amino group with 1 to 5 carbon atoms, dimethylamino group, diethylamino group, alkyl amino group with 2 to 5 carbon atoms, N-(tert-butoxycarbonyl)amino group, N-(tert-butoxycarbonyl)-N-methylamino group, N-(tert-butoxycarbonyl)-N-ethylamino group, N,N-di(tert-butoxycarbonyl)amino group, thiol group, alkyl thio group with 1 to 5 carbon atoms, etc.

[0026] In terms of improving the alignment of liquid crystals, the substituent F1 is preferably -OR1 or -NR2R3, more preferably -OR1.

[0027] From the viewpoint of achieving good liquid crystal alignment and adhesion, and improving the suppression of bright spots and the durability of buttons, it is preferable that both A1 and A2 have substituents F1 bonded to the aromatic ring. The number of substituents F1 in A1 and the number of substituents F1 in A2 are preferably 1 to 3, more preferably 1 or 2, and even more preferably 1.

[0028] The bonding position of the substituent F1 in the aromatic ring is not particularly limited. When the atom bonded to substituent F1 is adjacent to the atom bonded to B1 or B2 (or X if B1 and B2 are single bonds), the sensitivity to light can be further improved, resulting in a liquid crystal element exhibiting good liquid crystal alignment, which is advantageous in this respect. Furthermore, A1 and A2 are preferably located in the ring portion of the aromatic ring and therefore do not have substituents different from substituent F1.

[0029] Regarding B1 and B2, when R5, R6, or R7 contained in -NR5-, *1-CO-NR6-, or *1-NR6-CO-NR7- is a monovalent organic group, the monovalent organic group is preferably a monovalent hydrocarbon group having 1 to 10 carbon atoms or a thermally detachable group. Specific and preferred examples of R5, R6, or R7 being a monovalent hydrocarbon group having 1 to 10 carbon atoms or a thermally detachable group can be cited as examples of specific and preferred examples of R2 and R3. R5, R6, and R7 are preferably hydrogen atoms, alkyl groups having 1 to 3 carbon atoms, or thermally detachable groups, more preferably alkyl groups having 1 to 3 carbon atoms or tert-butoxycarbonyl groups.

[0030] From the viewpoint of obtaining a liquid crystal element exhibiting good liquid crystal alignment, B1 and B2 are preferably -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-, and more preferably -O-, -S- or -NR 5-.

[0031] Examples of divalent hydrocarbon groups represented by X include: chain hydrocarbon groups with 1 to 18 carbon atoms, alicyclic hydrocarbon groups with 3 to 18 carbon atoms, and aromatic hydrocarbon groups with 6 to 18 carbon atoms. In terms of forming a liquid crystal alignment film with high improvement in liquid crystal alignment and button durability, X is preferably a chain hydrocarbon group with 1 to 10 carbon atoms, an alicyclic hydrocarbon group with 3 to 10 carbon atoms, or an aromatic hydrocarbon group with 6 to 12 carbon atoms. In terms of further improving liquid crystal alignment or increasing film density, it is more preferably a straight-chain alkyl group with 1 to 5 carbon atoms, and even more preferably a methylene or 1,2-ethylene group.

[0032] Regarding the improvement effect of further enhancing liquid crystal alignment and button durability, polymer [A] is preferably having a partial structure (a) in the main chain, that is, the partial structure (a) constitutes part of the main chain of polymer [A]. The main skeleton of polymer [A] is not particularly limited. Regarding the ease of introducing the partial structure (a) into the main chain of the polymer, the ability to form a liquid crystal alignment film with high affinity for liquid crystal and high mechanical strength, and the high degree of freedom in monomer selection, polymer [A] is preferably having structural units derived from a diamine (hereinafter also referred to as "specific diamine") containing the partial structure (a), and more specifically, preferably having structural units derived from a compound represented by the following formula (2). [Chemistry 4] (In equation (2), A1, A2, B1, B2 and X have the same meaning as in equation (1))

[0033] Here, the term "main chain" refers to the "stem" portion of the polymer containing the longest atomic chain. Furthermore, the "stem" portion may contain ring structures. That is, "having a partial structure (a) in the main chain" means that partial structure (a) constitutes a part of the main chain. The term "side chain" refers to a portion that branches off from the polymer's "stem."

[0034] The specific diamine is particularly preferred to be a compound represented by the following formula (2A). [Chemistry 5] (In equation (2A), Z1 and Z2 are independently represented by the bases -OR1, -NR2R3, or -SR4, respectively; k1 and k2 are independently 1 or 2, respectively; when k1 is 2, multiple Z1s are the same or different; when k2 is 2, multiple Z2s are the same or different; R1, R2, R3, R4, B1, B2, and X have the same meaning as in equation (1).)

[0035] In equation (2A), Z1 and Z2 are preferably bases represented by -OR1 or -NR2R3.

[0036] When Z1 and Z2 are groups represented by -OR1, R1 is preferably a hydrogen atom, an alkyl group with 1 to 5 carbon atoms, a phenyl group, or a thermally detachable group, more preferably an alkyl group with 1 to 5 carbon atoms, and even more preferably an alkyl group with 1 to 3 carbon atoms. Furthermore, B1 and B2 are preferably -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-, more preferably -O-, -S-, or -NR 5-. X is preferably an alkyldiyl group with 1 or 2 carbon atoms, a divalent alicyclic hydrocarbon group, or a divalent aromatic hydrocarbon group, more preferably an alkyldiyl group with 1 or 2 carbon atoms.

[0037] When Z1 and Z2 are groups represented by -NR2R3, R2 is preferably a hydrogen atom, an alkyl group with 1 to 3 carbon atoms, a phenyl group, or a thermally detachable group, and R3 is preferably an alkyl group with 1 to 3 carbon atoms, a phenyl group, or a thermally detachable group. Furthermore, B1 and B2 are preferably -O-, -S-, or -NR5-, more preferably -O-. X is preferably an alkyldiyl group with 1 to 5 carbon atoms, a divalent alicyclic hydrocarbon group, or a divalent aromatic hydrocarbon group, more preferably an alkyldiyl group with 1 to 5 carbon atoms, and even more preferably an alkyldiyl group with 1 or 2 carbon atoms.

[0038] Specific examples of a particular diamine include compounds represented by formulas (4-1) to (4-24) below. Furthermore, in the formulas, "Boc" represents a tert-butoxycarbonyl group (the same applies below). [Chemistry 6] [Chemistry 7] [Chemistry 8] (In the formula, n is an integer from 1 to 18)

[0039] In the compounds represented by formulas (4-1) to (4-24), the bonding position of the substituent F1 on the benzene ring is not particularly limited. The bonding position of the substituent F1 is preferably at the 2- or 3-position relative to any group other than the primary amine group (i.e., B1 or B2 in formula (X if B1 or B2 is a single bond)). In particular, when the bonding position of the substituent F1 is at the 2-position relative to any group other than the primary amine group, high sensitivity can be achieved, and the alignment of the liquid crystal can be further improved; this is preferred in this respect.

[0040] From the viewpoint of achieving sufficiently high improvement in the liquid crystal alignment, adhesion, and button durability of the liquid crystal alignment film in polymer [A], and sufficiently suppressing the generation of bright spots in a liquid crystal element, the content ratio of structural units having partial structure (a) (hereinafter also referred to as "structural units (Ua)") is preferably 2 mol or more relative to the total amount of monomer units in polymer [A] (100 mol). The content ratio of structural units (Ua) is more preferably 5 mol or more relative to the total amount of monomer units in polymer [A] (100 mol), and even more preferably 10 mol or more. Furthermore, the content ratio of structural units (Ua) can be appropriately set according to the main chain of polymer [A], and is, for example, 50 mol or less relative to the total amount of monomer units in polymer [A] (100 mol). In addition, polymer [A] may have only one type of structural unit (Ua), or it may have two or more types.

[0041] Certain diamines can be synthesized by appropriately combining conventional organic chemistry methods. As an example, one method is to synthesize a dinitro group that replaces the primary amino group of the diamine having part of structure (a), and then nitroamine the obtained dinitro group using a suitable reduction system.

[0042] The method for synthesizing dinitro compounds can be appropriately selected according to the target compound. Examples include: a preferred method is to react a hydroxyl-containing compound with an aromatic ring structure having a substituent F1 bonded with a halide having a group X in an organic solvent, in the presence of a base and a catalyst as desired; a preferred method is to react a hydroxyl-containing compound with an aromatic ring structure having a substituent F1 bonded with a toluenesulfonic acid compound having a group X in an organic solvent, in the presence of a base and a catalyst as desired; a preferred method is to condense an acid halide with an aromatic ring structure having a substituent F1 bonded with an amino compound having a group X in an organic solvent, in the presence of a base and a catalyst as desired; a preferred method is to condense a carboxylic acid with an aromatic ring structure having a substituent F1 bonded with an amino compound having a group X in an organic solvent, in the presence of a base and a catalyst as desired, etc.

[0043] The reduction reaction of the dinitro group is preferably carried out using catalysts such as palladium on carbon, platinum oxide, zinc, iron, tin, and nickel in an organic solvent. Examples of organic solvents used herein include ethyl acetate, toluene, tetrahydrofuran, and alcohols. However, the synthetic formula for a specific diamine is not limited to the method described above.

[0044] This disclosure provides a diamine represented by the following formula (3). [Chemistry 9] (In formula (3), A3 and A4 are independently divalent aromatic ring groups; wherein, one or both of A3 and A4 have a structure formed by a group bond represented by -OR1a or -NR2aR3a bonded to an aromatic ring; R1a and R2a are independently monovalent hydrocarbon groups; R3a is a hydrogen atom or a monovalent organic group; B3 and B4 are independently single bonds, -O-, -S-, -NR5a-, -CO-, *1-CO-O-, *1-O-CO-, *1-CS-O-, *1-O-CS-, *1-CO-NR6a- or *1-NR6a-CO-NR7a-; R5a is a monovalent organic group; R6a and R7a are independently hydrogen atoms or monovalent organic groups; "*1" indicates a group bonded to A3 or A4.) 4. When B3 is -O-, Y is an alkyldiyl, divalent alicyclic hydrocarbon, or divalent aromatic hydrocarbon with 1 or 2 carbons; when B3 is *1-O-CO-, Y is an alkyldiyl, divalent alicyclic hydrocarbon with an aliphatic ring having 4 or more carbons, or divalent aromatic hydrocarbon; when B3 is other than -O- and *1-O-CO-, Y is a divalent hydrocarbon.

[0045] In formula (3), specific and preferred examples of the monovalent hydrocarbon groups represented by R1a and R2a, and the monovalent organic groups represented by R3a, can be given as the same groups as those exemplified as R1, R2, and R3 in formula (1). R1a and R2a are preferably monovalent hydrocarbon groups having 1 to 6 carbons, more preferably alkyl groups having 1 to 5 carbons and phenyl groups, and even more preferably alkyl groups having 1 to 3 carbons. R3a is preferably a hydrogen atom, an alkyl group having 1 to 5 carbons, a phenyl group, or a thermally detachable group, more preferably a hydrogen atom, an alkyl group having 1 to 3 carbons, or a tert-butoxycarbonyl group.

[0046] For specific and preferred examples of B3 and B4, the explanations of B1 and B2 in formula (1) can be applied. As a specific example of the divalent hydrocarbon group represented by Y, the same group as the group exemplified as the group represented by X in formula (1) can be listed.

[0047] When B3 is -O-, from the viewpoint of improving the alignment of the liquid crystal, Y is preferably an alkyl group with 1 or 2 carbon atoms, a divalent alicyclic hydrocarbon group having an aliphatic hydrocarbon ring with 4 or more carbon atoms, or a divalent aromatic hydrocarbon group. As a divalent alicyclic hydrocarbon group having an aliphatic hydrocarbon ring with 4 or more carbon atoms, from the viewpoint of achieving good liquid crystal alignment and high film density, it is preferably a cyclohexane ring. When B3 is -O-, Y is more preferably methylene or ethylene.

[0048] When B3 is *1-O-CO-, Y is preferably a straight-chain alkyldiyl group with 1 to 5 carbon atoms, more preferably methylene or ethylene. When B3 is other than -O- and *1-O-CO-, Y is preferably a chain hydrocarbon group with 1 to 10 carbon atoms, an alicyclic hydrocarbon group with 3 to 10 carbon atoms, or an aromatic hydrocarbon group with 6 to 12 carbon atoms. In terms of improving the alignment of the liquid crystal and increasing the film density, it is more preferably a straight-chain alkyldiyl group with 1 to 5 carbon atoms, and even more preferably methylene or ethylene.

[0049] The diamine represented by formula (3) is particularly preferred to be the compound represented by formula (3A) below. [Chemistry 10] (In equation (3A), Z3 and Z4 are independently represented by -OR1a or -NR2aR3a, respectively; k3 and k4 are independently 1 or 2, respectively; when k3 is 2, multiple Z3s are the same or different; when k4 is 2, multiple Z4s are the same or different; R1a, R2a, R3a, B3, B4 and Y have the same meaning as in equation (3).)

[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) where n is 1 or 2; and compounds represented by formulas (4-13), (4-18) and (4-22), etc.

[0051] In terms of forming a liquid crystal alignment film with high affinity for liquid crystal and high mechanical strength and reliability, the polymer [A] is preferably at least one selected from the group consisting of polyamide, polyamide ester and polyimide.

[0052] Polyamide When polymer [A] is polyamide, the polyamide (hereinafter also referred to as "polyamide [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 polyacrylic acid [A] include aliphatic tetracarboxylic dianhydrides and aromatic tetracarboxylic dianhydrides. Examples of aliphatic tetracarboxylic dianhydrides include chain tetracarboxylic dianhydrides and alicyclic tetracarboxylic dianhydrides.

[0054] Specific examples of these include 1,2,3,4-butanetetracarboxylic dianhydrides and ethylenediaminetetraacetic dianhydrides, among others, which are chain-like tetracarboxylic dianhydrides. Examples of alicyclic tetracarboxylic dianhydrides include: 1,2,3,4-cyclobutanetetracarboxylic dianhydrides, substituted cyclobutanetetracarboxylic dianhydrides, 2,3,5-tricarboxylated cyclopentylacetic acid dianhydrides, 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-tetracarboxylated bicyclo[3.3.0]octane-2:4,6:8-dianhydrides, cyclopentanetetracarboxylic dianhydrides, cyclohexanetetracarboxylic dianhydrides, etc., 3,5,6-tricarboxylated-2-carboxymethylnorbornene-2:3,5:6-dianhydrides, etc.

[0055] Examples of aromatic tetracarboxylic dianhydrides include: pyromellitic dianhydride, 4,4'-(hexafluoroisopropylidene)phthalic anhydride, ethylene glycol bis(triphenyl)-2-carboxylic anhydride, 4,4'-carbonyl phthalic anhydride, and 3,3',4,4'-biphenyltetracarboxylic dianhydride. Furthermore, the tetracarboxylic dianhydride described in Japanese Patent Application Publication No. 2010-97188 can be used as the synthesis of polyacrylic acid [A]. One tetracarboxylic dianhydride can be used alone, or two or more can be used in combination.

[0056] In terms of obtaining a liquid crystal alignment film with high solubility and exhibiting good liquid crystal alignment and electrical properties, the tetracarboxylic dianhydride used in the synthesis of polyacrylic acid [A] (and thus polymer [A]) preferably contains aliphatic tetracarboxylic dianhydride, more preferably contains alicyclic tetracarboxylic dianhydride. The proportion of aliphatic tetracarboxylic dianhydride-derived structural units in polymer [A] is preferably 20 mol% or more, more preferably 40 mol% or more, and even more preferably 50 mol% or more, relative to the total amount of tetracarboxylic dianhydride structural units derived from polymer [A].

[0057] In terms of producing a polymer with excellent photoalignment and reducing the generation of bright spots after photoalignment treatment by using it in combination with a specific diamine, polymer [A] preferably contains structural units derived from substituted cyclobutanetetracarboxylic dianhydrides. Specifically, polymer [A] preferably contains structural units having a partial structure represented by the following formula (4). [Chemistry 11] (In formula (4), R11, R12, R13 and R14 are each independently a hydrogen atom or a substituent; wherein, one or more of R11, R12, R13 and R14 are substituents; "*" indicates a bond)

[0058] In formula (4), the substituents represented by R11, R12, R13, and R14 (i.e., substituents that replace the cyclobutanetetracarboxylic acid dianhydride) can be categorized as: alkyl groups having 1 to 6 carbon atoms, alkyl halogenates having 1 to 6 carbon atoms, alkoxy groups having 1 to 6 carbon atoms, alkoxy halogenates having 1 to 6 carbon atoms, halogen atoms, etc. Among these, the substituents represented by R11, R12, R13, and R14 are preferably alkyl groups having 1 to 3 carbon atoms, alkyl halogenates having 1 to 3 carbon atoms, alkoxy groups having 1 to 3 carbon atoms, alkoxy halogenates having 1 to 3 carbon atoms, or halogen atoms, more preferably alkyl groups having 1 to 3 carbon atoms, fluoroalkyl groups having 1 to 3 carbon atoms, or fluorine atoms, and particularly preferably methyl groups.

[0059] Specific examples of tetracarboxylic dianhydrides having a partial structure 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, 1-ethyl-3-methyl- 1,2,3,4-Cyclobutanetetracarboxylic 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, 1,2,3,4-Tetra(trifluoromethyl)-1,2,3,4-Cyclobutanetetracarboxylic dianhydride, etc.

[0060] When polymer [A] contains structural units derived from substituted cyclobutanetetracarboxylic dianhydride, the proportion of structural units derived from substituted cyclobutanetetracarboxylic dianhydride 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 dianhydride in polymer [A].

[0061] (Diamine compounds) The diamine compound used in the synthesis of polyamide [A] may be only a specific diamine, or it may be used together with a specific diamine and a diamine that does not have part of structure (a) (hereinafter also referred to as "other diamines"). Examples of other diamines include: aliphatic diamines, aromatic diamines, and diamino organosiloxanes. Examples of aliphatic diamines include chain diamines and alicyclic diamines.

[0062] Specific examples of other diamines include: chain diamines such as meta-xylylenediamine and hexamethylenediamine; alicyclic diamines such as 1,4-diaminocyclohexane and 4,4'-methylenebis(cyclohexylamine); and aromatic diamines such as p-phenylenediamine, 1,4-diamino-2,5-dimethylbenzene, 4,4'-diaminodiphenylmethane, and 4,4'-diaminodiphenylmethane. Diphenyl ethane, 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-aminophenoxy)propane, 4,4'-diaminophenoxy)propane, 4,4'-diaminophenoxy)hexane, 4,4'-di(5-aminophenoxy)propane, 4,4'-diaminophenoxy)propane, 4,4'-diaminophenoxy)hexane, 4,4'-diaminophenoxy)propane, 4,4'-diaminophenoxy)propane, 4,4'-diaminophenoxy)hexane, 4,4'-diaminophenoxy)propane, 4,4'-diaminophenoxy)propane, 4,4'-diaminophenoxy)propane, 4,4'-diaminophenoxy)propane, 4,5 ... -amino-2-pyridyl)-N,N'-di(tert-butoxycarbonyl)ethylenediamine, bis[2-(4-aminophenyl)ethyl]adipic acid, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylamine, 4,4'-diaminodiphenylethyl urea, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 4,4'-(phenylene diisopropylidene)bisaniline, 2,6-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminochloroazole, N-methyl-3,6-diaminochloroazole, 3,6-diaminoacridine, monomers containing a diphenylamine structure, and compounds represented by the following formula (D-1) are main-chain diamines; [Chemistry 12] (In formula (D-1), R21 and R22 are each independently an alkyldiyl group; R23 is a hydrogen atom, an alkyl group with 1 to 3 carbon atoms, or a thermally detachable group; n1 is an integer from 1 to 3; when n1 is 2 or 3, multiple R22s may be the same or different from each other, and multiple R23s may be the same or different from each other.) Hexadecyloxy-2,4-diaminobenzene, Octadecyloxy-2,4-diaminobenzene, Octadecyloxy-2,5-diaminobenzene, Cholesteryloxy-3,5-diaminobenzene, Cholesteryloxy-3,5-diaminobenzene, Cholesteryloxy-2,4-diaminobenzene, Cholesteryloxy-2,4-diaminobenzene, Cholesteryl 3,5-diaminobenzoate, Cholesteryl 3,5-diaminobenzoate, 3,5-diaminobenzoate (Sheep) Side-chain diamines such as cyclohexyl esters, 3,6-bis(4-aminobenzoyloxy)cholestan, 3,6-bis(4-aminophenoxy)cholestan, 4-(4'-trifluoromethoxybenzoyloxy)cyclohexyl-3,5-diaminobenzoate, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-butylcyclohexane, 3,5-diaminobenzoic acid = 5ξ-cholestan-3-yl, and compounds represented by the following formula (E-1); [Chemistry 13] (In formula (E-1), XI and XII are independently single bonds, -O-, *-COO-, or *-OCO- (where "*" indicates a bond with the diaminophenyl side); RI is an alkyldiyl group with 1 to 3 carbon atoms; RII is a single bond or an alkyldiyl group with 1 to 3 carbon atoms; RIII is an alkyl, alkoxy, fluoroalkyl, or fluoroalkoxy group with 1 to 20 carbon atoms; a is 0 or 1; b is an integer from 0 to 3; c is an integer from 0 to 2; d is 0 or 1; where 1 ≦ a + b + c ≦ 3) 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). Examples of compounds represented by formula (E-1) include those represented by formulas (E-1-1) to (E-1-4). Other diamines may be used alone or in combination of two or more. [Chemistry 14]

[0064] In polyacrylic acid [A], from the viewpoint of fully improving the liquid crystal alignment, adhesion, and button durability of the liquid crystal alignment film and fully suppressing the generation of bright spots in the liquid crystal element, the proportion of structural units derived from a specific diamine 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 in the diamine compound derived from polyacrylic acid [A]. The specific diamine can be used alone or in combination with two or more.

[0065] Synthesis of polyacrylic acid Polyacrylic acid [A] can be obtained by reacting a tetracarboxylic dianhydride and a diamine compound with a molecular weight adjuster as needed. In the synthesis reaction of polyacrylic acid [A], the preferred ratio of tetracarboxylic dianhydride to diamine compound is 0.2 to 2 equivalents relative to the amino group of the diamine compound. Examples of molecular weight adjusters include: maleic anhydride, phthalic anhydride, itaconic anhydride, etc.; monoamine compounds such as aniline, cyclohexylamine, n-butylamine, etc.; and monoisocyanate compounds such as phenyl isocyanate, naphthyl isocyanate, etc. The preferred ratio of the molecular weight adjuster to the total 100 parts by mass of the tetracarboxylic dianhydride and diamine compound used is 20 parts by mass or less.

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

[0067] The above reaction yields a polymer solution in which polyacrylic acid [A] is dissolved. This polymer solution can be used directly in the preparation of liquid crystal alignment agents, or it can be used after separating the polyacrylic acid [A] from the polymer solution.

[0068] Polyamide When polymer [A] is a polyamide, the polyamide (hereinafter also referred to as "polyamide [A]") can be obtained, for example, by the following methods: [I] reacting polyamide [A] with an esterifying agent; [II] reacting a tetracarboxylic acid diester with a diamine compound containing a specific diamine; [III] reacting a tetracarboxylic acid diester dihalide with a diamine compound containing a specific diamine. Polyamide [A] may have only an amide structure, or it may be a partial esterification in which both an amide structure and an amide structure coexist. The reaction solution obtained by dissolving polyamide [A] can be directly used in the preparation of a liquid crystal alignment agent, or it can be used in the preparation of a liquid crystal alignment agent after separating the polyamide [A] contained in the reaction solution.

[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 polyacrylic acid [A] synthesized in the manner described above, followed by amide imidization. Polyimide [A] can be a fully amide imidized product formed by completely dehydrating and cyclizing the amide structure of polyacrylic acid [A], which is its precursor, or a partially amide imidized product formed by dehydrating and cyclizing only a portion of the amide structure, resulting in the coexistence of the amide structure and the amide ring structure. Polyimide [A] preferably has an amide imidization rate of 20% to 99%, more preferably 30% to 90%. Furthermore, the amide ratio is expressed as a percentage, representing the proportion of the number of amide ring structures relative to the total number of amide acid structures and amide ring structures in the polyamide. Here, a portion of the amide ring may be an isoamide ring.

[0070] The dehydration and ring-closure of polyacrylic acid [A] is preferably carried out by the following method: dissolving polyacrylic acid [A] in an organic solvent, adding a dehydrating agent and a dehydration and ring-closure catalyst to the solution, and heating as needed. In this method, anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride can be used as dehydrating agents. The amount of dehydrating agent used is preferably 0.01 mol to 20 mol relative to 1 mol of the polyacrylic acid structure of polyacrylic acid [A]. Tertiary amines such as pyridine, trimethylpyridine, dimethylpyridine, and triethylamine can be used as dehydration and ring-closure catalysts. The amount of dehydration and ring-closure catalyst used is preferably 0.01 mol to 10 mol relative to 1 mol of the dehydrating agent used. Examples of organic solvents used in the dehydration and ring-closure reaction include those used in the synthesis of polyacrylic acid [A]. The reaction temperature for the dehydration and ring-closure reaction is preferably 0°C to 180°C. The reaction time is preferably 1.0 hour to 120 hours. In addition, the reaction solution containing polyimide [A] can be used directly for the preparation of liquid crystal alignment agents, or the polyimide [A] can be separated and used for the preparation of liquid crystal alignment agents.

[0071] Regarding the potential for further improving the mechanical strength of the liquid crystal alignment film, polyimide [A] is preferably used as the polymer [A]. Based on the inventors' research, when polyamide is amide-iminated, there is a tendency for the mechanical strength or adhesion of the liquid crystal alignment film to decrease. On the other hand, polyimide has lower solubility than polyamide, which may easily lead to poor coating properties or film inhomogeneity. In this regard, polyimide [A] having partial structure (a) exhibits good solubility, thus allowing the formation of a liquid crystal alignment film with high mechanical strength while suppressing the decrease in coating properties or film uniformity.

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

[0073] The weight-average molecular weight (Mw) of polymer [A], determined by gel permeation chromatography (GPC) based on polystyrene, is preferably 1,000 to 500,000, 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) of polystyrene determined by GPC, is preferably 7 or less, more preferably 5 or less. In addition, when preparing the liquid crystal alignment agent, polymer [A] can be used alone or in combination of two or more.

[0074] <Other Ingredients> In addition to polymer [A], liquid crystal alignment agents may also contain components different from polymer [A] (hereinafter also referred to as "other components") as needed.

[0075] • Polymer [B] The liquid crystal alignment agent disclosed herein may further contain a polymer (hereinafter also referred to as "polymer [B]") that does not have part of structure (a) as a polymer component. The main framework of polymer [B] is not particularly limited. Other polymers include, for example: polyamide, polyamide ester, polyimide, polyorganosiloxane, polyester, polyenamine, polyurea, polyamide, polyamide-imide, polybenzoxazole precursor, polybenzoxazole, cellulose derivative, polyacetal, (meth)acrylic acid polymers, styrene polymers, maleimide polymers, styrene-maleimide copolymers, etc. From the viewpoint of obtaining a highly reliable liquid crystal element, polymer [B] is preferably selected from at least one of the group consisting of polyamide, polyamide ester, polyimide, polyorganosiloxane, and polymers comprising structural units derived from monomers having polymerizable unsaturated carbon-carbon bonds. Examples of polymers that contain structural units derived from monomers with polymerizable unsaturated carbon-carbon bonds include: (meth)acrylic polymers, styrene polymers, maleimide polymers, and styrene-maleimide copolymers.

[0076] When the liquid crystal alignment agent contains polymer [B], the content of polymer [B] is preferably 1% by mass or more, 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, 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.

[0077] Solvent The liquid crystal alignment agent disclosed herein is prepared as a liquid composition in which polymer [A] and other components used as needed are preferably dispersed or dissolved in a suitable solvent.

[0078] Organic solvents are preferably used. Specific examples include: N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,2-dimethyl-2-imidazolinone, 1,3-dimethyl-2-imidazolinone, phenol, γ-butyrolactone, γ-butyrolactone, 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, and acetoacetic acid. Methyl acetate, ethyl acetoate, ethyl propionate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-isopropyl ether, 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, diisoamyl 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, cyclohexanone, etc. As a solvent, it can be used alone or in combination with two or more.

[0079] Other components included in the liquid crystal alignment agent, besides those mentioned above, may include, for example, crosslinking agents, antioxidants, metal chelate compounds, curing accelerators, surfactants, fillers, dispersants, and photosensitizers. The proportions of these other components may be appropriately selected based on the specific compound, without compromising the effects of this disclosure.

[0080] The concentration of solid components in the liquid crystal alignment agent (the ratio of the total mass of components other than the solvent in the liquid crystal alignment agent to the total mass of the liquid crystal alignment agent) is appropriately selected considering factors such as viscosity and volatility. The preferred range for the solid component concentration of the liquid crystal alignment agent is 1% to 10% by mass. If the solid component concentration is 1% by mass or higher, sufficient film thickness can be ensured, and a liquid crystal alignment film exhibiting better liquid crystal alignment properties can be obtained, making it suitable in this respect. On the other hand, if the solid component concentration is 10% by mass or lower, there is a tendency to: the coating can be set to an appropriate thickness, a liquid crystal alignment film exhibiting good liquid crystal alignment properties can be easily obtained, and the viscosity of the liquid crystal alignment agent becomes moderate, resulting in good coatability.

[0081] Liquid crystal alignment film and its manufacturing method The liquid crystal alignment film of this disclosure can be manufactured using a liquid crystal alignment agent prepared in the manner described. Preferably, the liquid crystal alignment film of this disclosure can be manufactured by a method comprising the steps of forming a coating film using a liquid crystal alignment agent containing polymer [A] (coating film formation step); and the step of imparting liquid crystal alignment capability to the coating film by light irradiation (photoalignment treatment step).

[0082] • Coating formation steps In manufacturing a liquid crystal alignment film, firstly, a liquid crystal alignment agent is coated onto a substrate, preferably by heating the coated surface to form a coating on the substrate. Examples of substrates that can be used include: float glass, soda glass, etc.; and transparent substrates containing plastics such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, and poly(alicyclic olefins).

[0083] There are no particular limitations on the method for coating a liquid crystal alignment agent onto a substrate. The coating of the liquid crystal alignment agent onto the substrate can be performed by methods such as spin coating, printing (e.g., offset printing, flexographic printing), inkjet printing, slot coating, bar coating, extrusion die coating, direct gravure coating, chamber doctor coating, offset gravure coating, impregnation coating, and MB coating.

[0084] After coating the liquid crystal alignment agent, preheating (pre-baking) is preferably performed to prevent sagging of the coated liquid crystal alignment agent. The pre-baking temperature is preferably 30°C to 200°C, and the pre-baking time is preferably 0.25 minutes to 10 minutes. Then, the solvent is completely removed, and a calcination (post-baking) step is performed as needed for the purpose of thermally imidizing the acetic acid structure present in the polymer. The calcination temperature (post-baking temperature) at this time is preferably 80°C to 280°C, more preferably 80°C to 250°C. The post-baking time is preferably 5 minutes to 200 minutes. The thickness of the formed film is preferably 0.001 μm to 1 μm.

[0085] • Optical alignment processing steps Subsequently, the coating film formed through the aforementioned steps undergoes a photoalignment treatment, which is a process of irradiating the coating film with light (radiation irradiation) to impart liquid crystal alignment capability. Thus, a photoalignment film is obtained. The light irradiation for photoalignment can be performed by methods such as: irradiating the coating film after the post-baking step; irradiating the coating film after the pre-baking step and before the post-baking step; or irradiating the coating film during the heating process of either or both of the pre-baking and post-baking steps.

[0086] As the radiation irradiating the coating, for example, ultraviolet light and visible light containing wavelengths of 150 nm to 800 nm can be used. Ultraviolet light containing wavelengths of 200 nm to 400 nm is preferred. When the radiation is polarized, it can be linearly polarized or partially polarized. When the radiation used is linearly polarized or partially polarized, irradiation can be performed from a direction perpendicular to the substrate surface, from an oblique direction, or a combination of these directions. For unpolarized radiation, the irradiation direction is set to an oblique direction.

[0087] Examples of light sources used include low-pressure mercury lamps, high-pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonant lamps, xenon lamps, and excimer lasers. The radiation dose is preferably 200 J / m² to 30,000 J / m², more preferably 500 J / m² to 10,000 J / m². After irradiation with light to impart alignment capability, the substrate surface may be cleaned using, for example, water, an organic solvent (e.g., methanol, isopropanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, etc.), or a mixture thereof, or the substrate may be heated.

[0088] Liquid Crystal Components The liquid crystal element disclosed herein includes a liquid crystal alignment film formed using the liquid crystal alignment agent described herein. The driving method of the liquid crystal in the liquid crystal element is not particularly limited, and can be applied to various modes such as twisted nematic (TN), super twisted nematic (STN), vertical alignment (VA) (including vertical alignment-multi-domain vertical alignment (VA-MVA) and vertical alignment-patterned vertical alignment (VA-PVA), etc.), in-plane switching (IPS), fringe field switching (FFS), optically compensated bending (OCB), and polymer-stable alignment (PSA), etc. Liquid crystal elements can be manufactured, for example, by a method including the coating formation step, the photoalignment process step, and the following cell construction steps.

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

[0090] • Unit construction steps In the cell construction step, two substrates with liquid crystal alignment films formed by the aforementioned photoalignment treatment step are prepared, and liquid crystal cells are manufactured by placing liquid crystal between the two substrates facing each other. Methods for manufacturing liquid crystal cells include, for example, placing two substrates facing each other with a gap between them, bonding the peripheries of the two substrates together using a sealant, injecting and filling liquid crystal into the cell gap surrounded by the substrate surfaces and the sealant, and sealing the injection hole; and using a liquid crystal drop fill (ODF) method. For example, epoxy resin containing a hardener and alumina spheres as spacers can be used as a sealant.

[0091] As the liquid crystal, either positive or negative type can be used. When using negative liquid crystal in IPS and FFS type liquid crystal elements, the transmission loss at the top of the electrode can be reduced, and the contrast can be improved, which is preferable. In addition, in photodecomposable liquid crystal alignment films that exhibit anisotropy by polymer decomposition caused by light irradiation, thereby imparting liquid crystal alignment capability to the film, when using negative liquid crystal to fabricate liquid crystal elements, there is a tendency for a high rate of display defects (bright spots) caused by polymer decomposition products generated by radiation irradiation. In contrast, with the liquid crystal alignment agent of this disclosure, a high-quality liquid crystal element 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] In the manufacture of a liquid crystal display device, a polarizing plate is then attached to the outer surface of the liquid crystal cell. Examples of polarizing plates include: a polarizing plate made by clamping a polarizing film called an "H film" (one side of which is extended and aligned with polyvinyl alcohol and the other side absorbs iodine) with a cellulose acetate protective film, or a polarizing plate that includes the H film itself.

[0093] The liquid crystal element disclosed herein can be effectively applied to a variety of uses. Specifically, it can be used, for example, in clocks, portable games, word processors, notebook computers, car navigation systems, camcorders, personal digital assistants (PDAs), digital cameras, mobile phones, smartphones, various monitors, LCD TVs, information displays, and other display devices or dimming devices, phase retardation films, etc.

[0094] The following means can be provided through the above-described disclosure.

[0095] [Method 1] A method for manufacturing a liquid crystal alignment film includes: a step of forming a coating film by means of a liquid crystal alignment agent containing a polymer [A] having a partial structure (a) represented by the formula (1); and a step of irradiating the coating film with light to impart liquid crystal alignment capability. [Method 2] The method for manufacturing a liquid crystal alignment film according to [Method 1], wherein the polymer [A] has structural units derived from the compound represented by the formula (2). [Method 3] The method for manufacturing 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 polyamide, polyamide ester and polyimide. [Method 4] A method for manufacturing a liquid crystal alignment film according to any one of [Method 1] to [Method 3], wherein the polymer [A] has structural units derived from aliphatic tetracarboxylic dianhydrides. [Method 5] The method for manufacturing a liquid crystal alignment film according to [Method 4], wherein the aliphatic tetracarboxylic acid dianhydride has a partial structure represented by the formula (4). [Method 6] The method for manufacturing a liquid crystal alignment film according to any one of [Method 1] to [Method 5] further comprises a polymer [B] that does not have said partial structure (a). [Method 7] The method for manufacturing a liquid crystal alignment film according to [Method 6], wherein the polymer [B] is at least one selected from the group consisting of polyamide, polyamide ester and polyimide. [Means 8] A photoaligning agent comprising a polymer [A] having a partial structure (a) represented by the formula (1). [Mean 9] A liquid crystal element comprising a liquid crystal alignment film manufactured by any one of [Mean 1] to [Mean 7]. [Means 10] A polymer comprising structural units derived from a diamine represented by formula (3). [Method 11] A diamine, represented by the formula (3). [Example]

[0096] The following describes the implementation methods in more detail based on the embodiments, but the invention is not to be construed as limited by the following embodiments.

[0097] In the following examples, the amide content of polyimide in the polymer solution was determined by the following method. [Imidification rate of polyimide] The polyimide solution was added to pure water, and the resulting precipitate was dried under reduced pressure at room temperature. It was then dissolved in deuterated dimethyl silane, and 1H nuclear magnetic resonance (NMR) was performed at room temperature using tetramethylsilane as a reference. The amide concentration [%] was calculated from the obtained 1H-NMR spectrum using the following formula (I). Acrylimination rate [%] = (1 - (A1 / (A2×α))) × 100 ···(I) (In equation (I), A1 is the peak area of ​​protons originating from NH groups that appear near a chemical shift of 10 ppm, A2 is the peak area of ​​protons originating from other protons, and α is the ratio of the number of other protons to the number of one proton of NH groups in the polymer precursor (polyacrylic acid).)

[0098] The abbreviation for the compound is as described below. Furthermore, the compound represented by formula (X) (where X is a notation) is sometimes simply referred to as "compound (X)".

[0099] (Tetracarboxylic acid dianhydride) [Chemistry 15]

[0100] (Diamine compounds) [Chemistry 16] [Chemistry 17]

[0101] <Synthesis of Monomers> [Synthesis Example 1A] The following procedure was followed to synthesize compound (DA-1). [Chemistry 18]

[0102] In a three-necked flask containing a reflux tube and a nitrogen inlet tube, 23.72 g of 4-nitroguaiacol, 25.34 g of 1,2-bis(toluenesulfonyloxy)ethane, and 23.63 g of potassium carbonate were added, and the mixture was purged with nitrogen. 130 mL of dimethylformamide was added, and the mixture was slowly heated 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 the mixture was stirred for 1 hour. The precipitated crystals were filtered under reduced pressure, and the crude product was washed with water and 2-propanol, then dried under vacuum to obtain a powdered dinitromethyl intermediate (23.25 g, 93% yield). Subsequently, in a three-necked flask including a reflux tube and a nitrogen inlet tube, 23.25 g of the dinitroma intermediate and 408 mg of palladium on carbon were placed and 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 the addition, the temperature was slowly raised to 60°C and stirred for 4 hours. The reaction solution was diluted with tetrahydrofuran, filtered through diatomaceous earth, and concentrated to precipitate the product. The precipitate was washed with tetrahydrofuran (THF), and the crystals were filtered under reduced pressure. The crystals were washed with water and 2-propanol, and dried under vacuum to obtain a yellowish-brown solid compound (DA-1) (16.04 g, 79% yield). Its structure was confirmed by the nuclear magnetic resonance (1H-NMR) spectrum of the hydrogen atoms within the molecule. The measurement data are shown below. 1H-NMR (400 MHz, [D 6]-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] <Polymer Synthesis> 1. Synthesis of polyacrylic acid [Synthesis example 1] 100 moles of compound (TA-1) as a tetracarboxylic dianhydride, 40 moles of compound (DA-1) as a diamine compound, 40 moles of compound (DB-5) and 20 moles of compound (DB-8) were dissolved in N-methyl-2-pyrrolidone (NMP) and reacted at room temperature for 6 hours to obtain a solution containing 15% by mass of polyamide (designated as polymer (PA-1)).

[0104] [Synthesis Example 2~Synthesis Example 9] Except for changing the types and amounts of tetracarboxylic dianhydrides and diamine compounds used as described in Tables 1 and 2, the same operation as in Synthesis Example 1 was performed to obtain a solution containing 15% by mass of polyamide (polymer (PA-2) to polymer (PA-9)).

[0105] [Table 1] Polymer Name Acid dianhydride 1 Diamine 1 Diamine 2 Diamine 3 type Mörby type Mörby type Mörby type Mörby Synthesis example 1 PA-1 TA-1 100 DA-1 40 DB-5 40 DB-8 20 Synthesis example 2 PA-2 TA-1 100 DA-2 70 DB-3 20 DB-6 10

[0106] [Table 2] Polymer Name Acid dianhydride 1 acid dianhydride 2 Diamine 1 Diamine 2 type Mörby type Mörby type Mörby type Mörby Synthesis example 3 PA-3 TA-2 10 TA-6 90 DB-8 80 DB-11 20 Synthesis example 4 PA-4 TA-2 30 TA-1 70 DB-1 50 DB-12 50 Synthesis example 5 PA-5 TA-1 70 TA-3 30 DB-2 30 DB-13 70 Synthesis example 6 PA-6 TA-2 20 TA-3 80 DB-6 60 DB-14 40 Synthesis Example 7 PA-7 TA-2 70 TA-4 30 DB-9 80 DB-10 20 Synthesis example 8 PA-8 TA-2 100 DB-8 50 DB-15 50 Synthesis example 9 PA-9 TA-2 70 TA-5 30 DB-6 100

[0107] 2. Synthesis of polyimide [Synthesis Example 10] 90 moles of compound (TA-1) as a tetracarboxylic dianhydride, 10 moles of compound (TA-2) as a tetracarboxylic dianhydride, and 100 moles of compound (DA-1) as a diamine compound were dissolved in N-methyl-2-pyrrolidone (NMP) and reacted at room temperature for 6 hours to obtain a solution containing 15% by mass of polyamide. Subsequently, NMP was added to the obtained polyamide solution to prepare a solution with a polyamide concentration of 10% by mass. Pyridine and acetic anhydride were then added, and a dehydration and ring-closure reaction was carried out at 60°C for 4 hours. After the dehydration and ring-closure reaction, the solvent in the system was replaced with fresh NMP to obtain a solution containing 15% by mass of polyamide with a amide imidization rate of approximately 90% (designated as polymer (PI-1)).

[0108] [Synthesis Example 11~Synthesis Example 20] The types and amounts of tetracarboxylic acid dianhydride and diamine compounds used were changed as described in Table 3, and the amounts of pyridine and acetic anhydride were adjusted to achieve the amide ratio as described in Table 3, thereby obtaining a solution containing 15% by mass of polyamide (polymer (PI-2) to polymer (PI-11)).

[0109] [Table 3] Polymer Name Acid dianhydride 1 acid dianhydride 2 Diamine 1 Diamine 2 Diamine 3 aceimide rate type Mörby type Mörby type Mörby type Mörby type Mörby Synthesis example 10 PI-1 TA-1 90 TA-2 10 DA-1 100 90% Synthesis Example 11 PI-2 TA-1 100 DA-1 50 DB-3 20 DB-10 30 80% Synthesis example 12 PI-3 TA-1 70 TA-5 30 DA-2 100 40% Synthesis example 13 PI-4 TA-1 80 TA-6 20 DA-2 50 DB-5 50 50% Synthesis example 14 PI-5 TA-1 100 DA-3 60 DB-1 20 DB-4 20 60% Synthesis Example 15 PI-6 TA-1 100 DA-4 30 DB-7 50 DB-8 20 30% Synthesis example 16 PI-7 TA-1 80 TA-3 20 DA-5 40 DB-5 40 DB-9 20 80% Synthesis Example 17 PI-8 TA-1 100 DA-6 70 DB-9 30 80% Synthesis Example 18 PI-9 TA-1 100 DA-7 60 DB-3 40 70% Synthesis example 19 PI-10 TA-1 100 DA-8 30 DB-10 70 50% Synthesis example 20 PI-11 TA-1 100 DA-1 50 DB-10 30 DB-16 20 85%

[0110] <Preparation and Evaluation of Liquid Crystal Orientation Agents> [Implementation 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 such that the mass ratio of polymer (PA-1) to polymer (PA-3) was (PA-1) / (PA-3) = 30 / 70. The mixture was then diluted with NMP and butyl cellosolve (BC) to prepare a solution with a solvent composition of NMP / BC = 80 / 20 and a solid content concentration of 3.5% by mass. The solution was filtered using a 0.2 μm sieve to prepare the liquid crystal alignment agent (AL-1).

[0111] 2. Manufacturing of FFS-type liquid crystal display elements using photoalignment method A glass substrate (designated as the first substrate) and a glass substrate without electrodes (designated as the second substrate) are prepared by sequentially stacking a flat plate electrode (bottom electrode), an insulating layer, and a comb-shaped electrode (top electrode) on a single side. Then, a liquid crystal alignment agent (AL-1) is applied to the electrode forming surface of the first substrate and a single side of the second substrate using a spinner, and heated (pre-baked) at 80°C for 1 minute using a hot plate. Next, it is dried (post-baked) for 30 minutes in a 150°C oven with nitrogen purging, forming a coating with an average thickness of 0.1 μm. Photoalignment treatment is performed by irradiating the obtained coating with 1,000 J / m² of ultraviolet light containing a linearly polarized 254 nm bright line from the substrate normal direction using an Hg-Xe lamp. The irradiation amount is measured using a photometer with a wavelength of 254 nm as the reference. Subsequently, the coating that has undergone photoalignment treatment is heat-treated by heating it in a clean oven at 150°C for 30 minutes to form a liquid crystal alignment film. Next, for one of a pair of substrates with a liquid crystal alignment film, an epoxy resin adhesive containing alumina spheres with a diameter of 3.5 μm is applied to the outer edge of the surface with the liquid crystal alignment film by screen printing. Then, the substrates are overlapped and pressed together so that the projection direction of the polarization axis on the substrate surface during light irradiation is antiparallel, and the adhesive is thermosetting at 150°C for 1 hour. Subsequently, negative liquid crystal (manufactured by Merck, MLC-6608) is filled between the pair of substrates through the liquid crystal injection port, and the liquid crystal injection port is sealed with an epoxy adhesive to obtain a liquid crystal cell. Furthermore, in order to remove the flow alignment during liquid crystal injection, it is heated at 120°C and then slowly cooled to room temperature. Then, a polarizing plate is attached to the outer sides of the substrate in the liquid crystal cell to obtain a liquid crystal display element. Furthermore, by performing the aforementioned series of operations by varying the post-baking ultraviolet irradiation amount within the range of 100 J / m² to 10,000 J / m², three or more liquid crystal display elements with different ultraviolet irradiation amounts were manufactured. The liquid crystal display element exhibiting the best alignment characteristics (optimal exposure amount) was used for the following evaluation.

[0112] 3. Evaluation of liquid crystal alignment The liquid crystal display element manufactured in step 2 was placed under a high-brightness backlight of 27,000 cd / m² for 500 hours, and the liquid crystal alignment was evaluated based on the rate of change of retardation α before and after backlight illumination. The retardation was measured using an Axoscan instrument manufactured by Opto Science, and the rate of change of retardation α before and after backlight illumination was calculated using the following formula (II). It can be said that the smaller the rate of change α, the better the liquid crystal alignment. A rate of change α of 0.5% or less was defined as "excellent (◎)", a rate of change α of more than 0.5% but less than 1% was defined as "good (○)", a rate of change α of more than 1% but less than 2% was defined as "acceptable (△)", and a rate of change α of more than 2% was defined as "poor (×)". α = Δθ / θ1 ···(II) (In Equation (II), Δθ represents the delay difference before and after irradiation, and θ1 represents the delay value before irradiation.) As a result, the liquid crystal alignment of the embodiment was rated as "good (○)".

[0113] 4. Evaluation of bright spots (bright spot suppression) in liquid crystal cells The liquid crystal cell manufactured in step 2 was observed using a polarizing microscope (ECLIPSE E600WPOL) (manufactured by Nikon Corporation), and the bright spot suppression performance was evaluated. Specifically, the liquid crystal cell was placed between two polarizing plates arranged orthogonally to the polarizing axes, and the liquid crystal cell was observed using a polarizing microscope with a magnification of 5x (observation area: approximately 2500 μm × 2500 μm). It can be said that the fewer the number of bright spots, the fewer the decomposition products obtained based on photoalignment processing, which is better. Cases with more than 100 bright spots were defined as "poor (×)", cases with more than 10 but less than 100 bright spots were defined as "acceptable (△)", and cases with less than 10 bright spots were defined as "good (○)". As a result, in the above embodiment, it was "good (○)".

[0114] 5. Evaluation of button durability based on button testing For the liquid crystal display element manufactured in section 2, the liquid crystal alignment after a button test was evaluated. The evaluation was conducted as follows: A silicone rubber pen 3R (manufactured by Touch Panel Research & Development Co., Ltd.) with a 3 mm radius tip was used on the button section (soleix type) of a button testing machine (manufactured by Touch Panel Research & Development Co., Ltd.), with the tip positioned at the center of the liquid crystal display element. After pressing the button 10,000 times at 10 Hz under a load of 500 g, the liquid crystal display element was observed under a microscope (100x magnification) and the number of bright spots was measured. It can be said that the fewer the number of bright spots, the better the button durability of the liquid crystal display element. A number of bright spots less than 30 was judged as "excellent (◎)", 30 or more but less than 50 was judged as "good (○)", 50 or more but less than 100 was judged as "acceptable (△)", and more than 100 was judged as "poor (×)". The result in the above embodiment was an evaluation of "good (○)".

[0115] 6. Evaluation of fit The liquid crystal alignment agent (AL-1) prepared in step 1 was coated onto a glass substrate using a spinner. After pre-baking on a hot plate at 80°C for 2 minutes, it was heated for 30 minutes in a 230°C oven with nitrogen purging (post-baking) to form a coating with an average thickness of 0.10 μm. Two coated glass substrates were prepared by repeating the same operation. On the coating of one glass substrate, an ODF sealant (manufactured by Sekisui Chemicals, S-WB42) was applied with a width of 1 mm, and the two substrates were bonded together with the ODF sealant in contact with the coating. The substrates were then irradiated with 30,000 J / m² (converted to 365 nm) of light using a metal halide lamp and heated in an oven at 120°C for 1 hour. The adhesion was then evaluated by measuring the adhesion force using a tensile compression testing machine (manufactured by Imada Seisakusho, model: SDWS-0201-100SL). Regarding the evaluation, a sealing force of 175 N / cm² or higher is designated as "Good (○)", a sealing force of 125 N / cm² or higher but less than 175 N / cm² is designated as "Acceptable (△)", and a sealing force less than 125 N / cm² is designated as "Poor (×)". As a result, in the described embodiment, the sealing force is 175 N / cm², which is rated as "Good (○)".

[0116] [Examples 2-12 and Comparative Examples 1-3] Except for changing the composition of the liquid crystal alignment agent as shown in Table 4, the liquid crystal alignment agent was prepared in the same manner as in Example 1. Furthermore, using the obtained liquid crystal alignment agent, an FFS-type liquid crystal display element was manufactured by photoalignment in the same manner as in Example 1, and the liquid crystal alignment, bright spot suppression, button durability, and sealing performance were evaluated. These results are shown in Table 4. In addition, in Examples 2, 4, 6, 8-10, 12, and Comparative Examples 2 and 3, two polymers were used as polymer components; in Examples 5, 7, and 11, three polymers were used as polymer components. In Table 4, the values ​​in the polymer column represent the mixing ratio (parts by mass) of each polymer relative to 100 parts by mass of the total polymer components used in the preparation of the liquid crystal alignment agent, based on the solid content.

[0117] [Table 4] Orientation agent composition Feature Evaluation Polymer 1 Polymer 2 Polymer 3 Liquid crystal alignment Highlights of the LCD unit Button test tightness type mass ratio type mass ratio type mass ratio Example 1 PA-1 30 PA-3 70 ○ ○ ○ ○ Example 2 PA-2 50 PA-4 50 ○ ○ ◎ ○ Example 3 PI-1 100 ◎ ○ ○ ○ Example 4 PI-1 20 PA-5 80 ◎ ○ ○ ○ Example 5 PI-2 30 PA-6 30 PA-8 40 ◎ ○ ○ ○ Example 6 PI-2 40 PA-3 60 ◎ ○ ○ ○ Example 7 PI-3 10 PA-5 30 PA-7 60 ○ ○ ◎ ○ Example 8 PI-4 10 PA-6 90 ○ ○ ◎ ○ Example 9 PI-5 10 PA-7 90 △ ○ ○ ○ Example 10 PI-6 30 PA-8 70 ○ ○ ○ ○ Example 11 PI-7 30 PA-4 30 PA-9 40 △ ○ ○ ○ Example 12 PI-11 40 PA-3 60 ◎ ○ ○ ○ Comparative Example 1 PI-8 100 △ × × × Comparative Example 2 PI-9 20 PA-6 80 △ ○ × △ Comparative Example 3 PI-10 30 PA-5 70 × ○ ○ ○

[0118] As shown in Table 4, Examples 1 to 12, which used liquid crystal alignment agents containing polymer [A], compared with Comparative Examples 1 to 3, which used liquid crystal alignment agents without polymer [A], achieved a good balance in terms of liquid crystal alignment, bright spot suppression of liquid crystal cells, button durability, and film adhesion.

[0119] Based on the above results, it is clear that by using a liquid crystal alignment agent containing polymer [A], a liquid crystal element with excellent liquid crystal alignment, button durability and sealing performance, and with fewer bright spots in the liquid crystal cell can be obtained.

Claims

1. A method for manufacturing a liquid crystal alignment film, including: The steps are: forming a coating film by means of a liquid crystal alignment agent containing a polymer [A] having a partial structure (a) represented by the following formula (1); and irradiating the coating film with light to impart liquid crystal alignment capability, wherein in formula (1), A1 and A2 are each independently divalent aromatic ring groups; wherein one or both of A1 and A2 have a structure formed by a group bonded to an aromatic ring as represented by -OR1, -NR2R3 or -SR4; R1, R2 and R4 are each independently hydrogen atoms or monovalent organic groups; R3 is a monovalent organic group; B1 and B2 are each independently -O-, -S- or -NR5-; R5 is a monovalent hydrocarbon group or a thermally detachable group having 1 to 10 carbon atoms; X is a divalent hydrocarbon group; "*" indicates a bond.

2. A method for manufacturing a liquid crystal alignment film as claimed in claim 1, wherein the polymer [A] has structural units derived from a compound represented by the following formula (2); in formula (2), A1, A2, B1, B2 and X have the same meaning as in formula (1).

3. The method for manufacturing a liquid crystal alignment film as claimed in claim 1, wherein the polymer [A] is at least one selected from the group consisting of polyamide, polyamide ester and polyimide.

4. A method for manufacturing a liquid crystal alignment film as claimed in claim 3, wherein the polymer [A] has structural units derived from aliphatic tetracarboxylic acid dianhydrides.

5. A method for manufacturing a liquid crystal alignment film as claimed in claim 4, wherein the aliphatic tetracarboxylic acid dianhydride has a partial structure represented by the following formula (4); in formula (4), R11, R12, R13 and R14 are each independently a hydrogen atom or a substituent; wherein, One or more of R11, R12, R13, and R14 are substituents; "*" indicates a bond.

6. The method for manufacturing a liquid crystal alignment film as claimed in claim 1 further comprises a polymer [B] that does not have said partial structure (a).

7. A method for manufacturing a liquid crystal alignment film as claimed in claim 6, wherein the polymer [B] is at least one selected from the group consisting of polyamide, polyamide ester and polyimide.

8. A photoaligning agent comprising a polymer [A] having a partial structure (a) represented by the following formula (1); wherein, in formula (1), A1 and A2 are each independently a divalent aromatic cyclic group; wherein, One or both of A1 and A2 have a structure formed by a group bonded to an aromatic ring, represented by -OR1, -NR2R3 or -SR4; R1, R2 and R4 are each independently a hydrogen atom or a monovalent organic group; R3 is a monovalent organic group; B1 and B2 are each independently -O-, -S- or -NR5-; R5 is a monovalent hydrocarbon group or a thermally detachable group with 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 by a method for manufacturing a liquid crystal alignment film as described in any one of claims 1 to 7.

10. A polymer comprising structural units derived from a diamine represented by formula (3) below; wherein, A3 and A4 are each independently a divalent aromatic cyclic group; wherein, One or both of A3 and A4 have a structure formed by a group bonded to an aromatic ring as represented by -OR1a or -NR2aR3a; R1a and R2a are each independently monovalent hydrocarbon groups; R3a is a hydrogen atom or a monovalent organic group; B3 and B4 are each independently -O-, -S-, or -NR5a-; R5a is a monovalent hydrocarbon group or a thermally detachable group with 1 to 10 carbon atoms; when B3 is -O-, Y is an alkyldiyl, a divalent alicyclic hydrocarbon group, or a divalent aromatic hydrocarbon group with 1 or 2 carbon atoms; when B3 is not -O-, Y is a divalent hydrocarbon group.

11. A diamine, represented by the following formula (3); in formula (3), A3 and A4 are each independently a divalent aromatic cyclic group; wherein, One or both of A3 and A4 have a structure formed by a group bonded to an aromatic ring as represented by -OR1a or -NR2aR3a; R1a and R2a are each independently monovalent hydrocarbon groups; R3a is a hydrogen atom or a monovalent organic group; B3 and B4 are each independently -O-, -S-, or -NR5a-; R5a is a monovalent hydrocarbon group or a thermally detachable group with 1 to 10 carbon atoms; when B3 is -O-, Y is an alkyldiyl, a divalent alicyclic hydrocarbon group, or a divalent aromatic hydrocarbon group with 1 or 2 carbon atoms; when B3 is not -O-, Y is a divalent hydrocarbon group.