Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal display element

Abstract

Provided is a liquid crystal alignment agent that can be suitably used for a liquid crystal alignment film having high film strength and for a liquid crystal display element in which AC afterimages are suppressed, and that does not precipitate solid content when being stored at a low temperature. Further provided are a liquid crystal alignment film obtained from said liquid crystal alignment agent, and a liquid crystal display element having said liquid crystal alignment film.　The liquid crystal alignment agent contains a component (A) and a component (B). Component (A): A polymer (A) having the ability to align liquid crystals. Component (B): A hydroxyalkylamide compound (B) represented by formula (1). (R represents a C1-6 alkyl group, R1 and R2 each independently represent a hydrogen atom or a C1-6 monovalent organic group, and A represents a C1-30 divalent organic group.)

Description

[Technical field]

[0001] The present invention relates to a liquid crystal aligning agent, a liquid crystal alignment film, and a liquid crystal display element. [Background technology]

[0002] Conventionally, liquid crystal display devices have been widely used as display units for personal computers, smartphones, mobile phones, television receivers, etc. A liquid crystal display device includes, for example, a liquid crystal layer sandwiched between an element substrate and a color filter substrate, pixel electrodes and a common electrode for applying an electric field to the liquid crystal layer, an alignment film for controlling the alignment of liquid crystal molecules in the liquid crystal layer, and thin film transistors (TFTs) for switching electric signals supplied to the pixel electrodes. Known driving methods for liquid crystal molecules include vertical electric field methods such as the Twisted Nematic (TN) method and the Vertical Alignment (VA) method, and horizontal electric field methods such as the In-Plane Switching (IPS) method and the Fringe Field Switching (FFS) method.

[0003] At present, the most industrially widespread liquid crystal alignment film is produced by rubbing the surface of a film formed on an electrode substrate, which is made of a polymer such as polyamic acid and / or polyimide obtained by imidizing the polyamic acid, in one direction with a cloth such as cotton, nylon, or polyester. The rubbing process is a simple and industrially useful method with excellent productivity. However, with the increase in performance, definition, and size of liquid crystal display elements, various problems have become evident, such as scratches on the surface of the alignment film caused by the rubbing process, dust generation, effects due to mechanical force and static electricity, and even non-uniformity within the alignment treatment surface. As an alignment treatment method replacing the rubbing process, a photoalignment method is known in which liquid crystal alignment ability is imparted by irradiating polarized radiation. As for the photoalignment method, methods utilizing photoisomerization reaction, photocrosslinking reaction, photodecomposition reaction, and the like have been proposed (see, for example, Non-Patent Document 1 and Patent Document 1).

[0004] In recent years, large-screen, high-definition LCD televisions have become mainstream, and small display terminals such as smartphones, tablet PCs, and car navigation systems have become more widespread, so that the demand for high quality LCD elements is even higher than before. As a reliability test for LCD elements for mobile applications such as smartphones and in-vehicle applications such as car navigation systems, a vibration test of the panel may be performed. In this vibration test, it is required that defects such as bright spots do not occur. In order to obtain LCD elements that do not cause defects after the vibration test, for example, a method of increasing the mechanical strength of the liquid crystal alignment film can be considered. As a method of improving the mechanical strength of the liquid crystal alignment film, particularly the film strength, a method of adding a crosslinking agent to the liquid crystal alignment agent can be mentioned. In addition, the stability of liquid crystal alignment is also important in the IPS and FFS driving methods. If the alignment stability is low, the liquid crystal will not return to its initial state when driven for a long time, which can cause a decrease in contrast and image retention (hereafter referred to as AC image retention). As a means for solving these problems, a liquid crystal aligning agent containing a specific polyimide component and a specific hydroxyalkylamide compound has been proposed (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-297313 [Patent Document 2] WO2018 / 092811 publication [Non-patent literature]

[0006] [Non-Patent Document 1] "Liquid Crystal Photo-Alignment Film" Kidowaki, Ichimura, Functional Materials, November 1997, Vol. 17, No. 11, pp. 13-22 Summary of the Invention [Problem to be solved by the invention]

[0007] Between production and shipment, the liquid crystal alignment agent is usually stored in an extremely low temperature environment (for example, at −20° C.) in order to prevent deterioration of the polymer. On the other hand, the inventors' research has revealed that when the hydroxyalkylamide compound described in Patent Document 2 is added to a liquid crystal alignment agent, the film strength of the resulting liquid crystal alignment film is improved and a liquid crystal display element with suppressed AC image retention is obtained, but the solid content contained in the liquid crystal alignment agent precipitates during storage at low temperatures. Once solid matter has precipitated, it is difficult to dissolve it again, and there is a risk of causing problems such as printing defects in the manufacturing process of liquid crystal display elements. The cause of such precipitation of solid matter is unclear, but it is presumed that one of the causes is the high polarity of the hydroxyalkylamide compound used in the liquid crystal alignment agent. Therefore, there is a demand for a liquid crystal alignment agent that does not cause precipitation of solid matter even during freezing and storage.

[0008] In view of the above, the present invention aims to provide a liquid crystal aligning agent that can be suitably used for a liquid crystal alignment film having high film strength and a liquid crystal display element in which AC afterimages are suppressed, and that does not precipitate solids during low-temperature storage. Further, the present invention aims to provide a liquid crystal alignment film obtained from the liquid crystal aligning agent, and a liquid crystal display element having the liquid crystal alignment film. [Means for solving the problem]

[0009] As a result of intensive research to achieve the above object, the present inventors have found that a liquid crystal aligning agent containing a specific hydroxyalkylamide compound is extremely effective in achieving the above object, and have completed the present invention.

[0010] The present invention includes the following aspects. [1] A liquid crystal aligning agent comprising the following components (A) and (B): Component (A): Polymer (A) capable of aligning liquid crystals Component (B): a hydroxyalkylamide compound (B) represented by the following formula (1): [ka] (R is an alkyl group having 1 to 6 carbon atoms, R1 and R2 each independently represent a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms, and A represents a divalent organic group having 1 to 30 carbon atoms.)

[0011] Another aspect of the present invention includes the following aspects. [1] A liquid crystal aligning agent comprising the following components (A') and (B'): Component (A'): Polymer (A') capable of aligning liquid crystal Component (B'): a hydroxyalkylamide compound (B') represented by the following formula (1'): [ka] (R' is a group "*-C(R 2’ )2-C(R 1’ )2-OH" (* represents a bond. R 1’ , R 2’ each independently represents a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms; R' may be the same or different; and n is an integer of 1 to 30. 1’ is a divalent organic group having 1 to 10 carbon atoms, and multiple L 1’ may be the same or different.) Effect of the Invention

[0012] According to the present invention, it is possible to provide a liquid crystal alignment agent that can be suitably used for a liquid crystal alignment film having high film strength and a liquid crystal display element in which AC afterimages are suppressed, and which does not precipitate solids when stored at low temperatures, as well as a liquid crystal alignment film obtained from the liquid crystal alignment agent, and a liquid crystal display element having the liquid crystal alignment film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, a liquid crystal alignment agent containing a specific hydroxyalkylamide compound, a liquid crystal alignment film formed using the liquid crystal alignment agent, and a liquid crystal display element having the liquid crystal alignment film will be described in detail. However, the explanation of the constituent elements described below is an example of one embodiment of the present invention, and the present invention is not limited to these contents. In the following description, the term "(meth)acrylic" refers to both acrylic and methacrylic. Furthermore, examples of the "halogen atom" include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0014] (Liquid crystal alignment agent) The liquid crystal aligning agent of the present invention contains a polymer (A) (also referred to as component (A) in the present invention) or a polymer (A') (also referred to as component (A') in the present invention) having the ability to align liquid crystals. The polymer (A') may be the same compound as the polymer (A), including preferred specific examples. Moreover, one embodiment of the liquid crystal aligning agent of the present invention contains the above polymer (A) and a hydroxyalkylamide compound (B) represented by the above formula (1) (also referred to as component (B) in the present invention). Another embodiment of the liquid crystal aligning agent of the present invention contains the above polymer (A') and a hydroxyalkylamide compound (B') represented by the above formula (1') (also referred to as the (B') component in the present invention).

[0015] <Component (A) and Component (A')> The liquid crystal aligning agent of the present invention contains a polymer capable of aligning liquid crystals, similar to known ones, but such a polymer is not particularly limited as long as it has the ability to align liquid crystals. Examples of such polymers include polyimide precursors, polyimides which are imidized products of polyimide precursors, acrylic polymers, methacrylic polymers, acrylamide polymers, methacrylamide polymers, polystyrene, polysiloxanes, polyamides, polyesters, polyurethanes, polycarbonates, polyureas, polyphenols (novolac resins), maleimide polymers, and polymers into which a compound having an isocyanuric acid skeleton or a triazine skeleton has been introduced.

[0016] The raw materials for producing these polymers include the following. When the polymer is a polyimide or a polyimide precursor such as polyamic acid or polyamic acid ester, examples of the polymer include at least one compound selected from tetracarboxylic acids or derivatives thereof (preferably tetracarboxylic dianhydride) and a diamine. When the polymer is a (meth)acrylic polymer, examples of the polymer include (meth)acrylic acid or a derivative thereof, and a (meth)acrylic acid ester or a derivative thereof. When the polymer is a (meth)acrylamide polymer, examples of the polymer include (meth)acrylamide and its derivatives.

[0017] When the polymer is polystyrene, examples of the polymer include styrene and its derivatives. When the polymer is a polysiloxane, examples of the polymer include silane compounds having a methoxy group or an ethoxy group. When the polymer is a polyamide, the polymer includes at least one dicarboxylic acid component selected from dicarboxylic acids and derivatives thereof, and a diamine component. When the polymer is a polyester, the polymer includes at least one dicarboxylic acid component selected from dicarboxylic acids and derivatives thereof, and a diol component.

[0018] When the polymer is polyurethane, examples of the polymer include an isocyanate compound and a compound having a hydroxy group. When the polymer is a polycarbonate, examples include bisphenol derivatives and phosgene or phosgene equivalents (eg, trichlorophosgene) or diphenyl carbonate. When the polymer is polyurea, examples of the component include a bisisocyanate derivative and a diamine component. When the polymer is a maleimide polymer, the polymer may be a maleimide derivative alone or a copolymer with styrene. In the case where the polymer is a polymer into which a compound having an isocyanuric acid skeleton or a triazine skeleton has been introduced, examples of the compound include a compound having an isocyanuric acid skeleton or a triazine skeleton.

[0019] <<Polyimide polymer>> As the polymer contained in the liquid crystal aligning agent of the present invention, from the viewpoints of practicality as a liquid crystal aligning agent, mechanical strength of the coating film, and liquid crystal alignment property, it is preferable to use one or more polymers selected from the group consisting of polyimide precursors and polyimides which are imidized products of polyimide precursors (hereinafter also referred to as polyimide-based polymers). The polyimide polymer can be produced by a known method. For example, a polyamic acid, which is a polyimide precursor, is obtained by polymerizing (polycondensing) a tetracarboxylic acid component made of a tetracarboxylic dianhydride or a derivative thereof with a diamine component, and a polyimide is obtained by imidizing the polyimide precursor. Examples of derivatives of tetracarboxylic dianhydride include tetracarboxylic acid dihalides, tetracarboxylic acid dialkyl esters, and tetracarboxylic acid dialkyl ester dihalides.

[0020] <<<Tetracarboxylic acid component>>> The polyamic acid, which is a polyimide precursor, may be, for example, one obtained from a tetracarboxylic acid component containing an aromatic, acyclic aliphatic, or alicyclic tetracarboxylic acid dianhydride. Here, the aromatic tetracarboxylic acid dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxy groups, including at least one carboxy group bonded to an aromatic ring. The acyclic aliphatic tetracarboxylic acid dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxy groups bonded to a chain hydrocarbon structure. However, it is not necessary for the polyamic acid dianhydride to be composed only of a chain hydrocarbon structure, and it may have an alicyclic structure or an aromatic ring structure as a part of it.

[0021] An alicyclic tetracarboxylic dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxy groups, including at least one carboxy group bonded to an alicyclic structure, but none of the four carboxy groups are bonded to an aromatic ring. Furthermore, it is not necessary for the structure to be composed solely of an alicyclic structure, and it may also contain a chain hydrocarbon structure or an aromatic ring structure as part of it.

[0022] The polyamic acid according to the present invention is preferably one obtained from a tetracarboxylic acid component containing a tetracarboxylic dianhydride represented by the following formula (2).

[0023] [ka] (X represents a structure selected from the following formulas (x-1) to (x-13).)

[0024] [ka] (R 1 ~R 4 R each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms and containing a fluorine atom, or a phenyl group. 5 and R 6 Each of A1 and A2 independently represents a hydrogen atom or a methyl group. j and k are integers of 0 or 1, and A1 and A2 independently represent a single bond, -O-, -CO-, -COO-, a phenylene group, a sulfonyl group, or an amide group. A2 may be the same or different. *1 is a bond bonded to one acid anhydride group, and *2 is a bond bonded to the other acid anhydride group.

[0025] Preferred specific examples of the tetracarboxylic dianhydride or derivative thereof represented by the above formula (2) include those in which X is selected from the above formulas (x-1) to (x-8) and (x-10) to (x-13).

[0026] The above formula (x-1) is preferably one selected from the group consisting of the following formulas (x1-1) to (x1-6).

[0027] [ka] (*1 is the bond bonded to one acid anhydride group, and *2 is the bond bonded to the other acid anhydride group.)

[0028] Preferred specific examples of the above formulae (x-12) and (x-13) include the following formulae (x-14) to (x-29), in which "*" indicates a bonding position.

[0029] [ka]

[0030] [ka]

[0031] The amount of the tetracarboxylic dianhydride represented by the above formula (2) or a derivative thereof used is preferably 60 to 100 mol %, more preferably 80 to 100 mol %, and even more preferably 90 to 100 mol %, based on 1 mol of the total tetracarboxylic acid components to be reacted with the diamine components.

[0032] <<<Diamine component>>> The diamine component used in the production of the polyimide precursor is not particularly limited, but is preferably a diamine component containing at least one diamine selected from the diamines represented by the following formulas (3) and (3i).

[0033] [ka] (Y3 represents a divalent organic group represented by the following formula (O). R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Y 3i represents a divalent organic group represented by the following formula (O').

[0034] [ka] (Ar represents a divalent benzene ring, a biphenyl structure, or a naphthalene ring. Two Ar may be the same or different, and any hydrogen atom in the ring may be substituted with a monovalent substituent. p is an integer of 0 or 1. Q3 is -(CH2) n -(n is an integer of 2 to 18), or the above -(CH2) n represents a group in which at least a portion of the -CH2- is replaced with -O-, -C(=O)-, or -OC(=O)-. * represents a bond.

[0035] [ka] (Ar' represents a divalent benzene ring or a biphenyl structure. Two Ar' may be the same or different, and any hydrogen atom in the ring may be substituted with a monovalent substituent. p' is an integer of 0 or 1. Q 3’ Ha-(CH2) n -(n is an integer of 2 to 18), or the above -(CH2) n represents a group in which at least a portion of the -CH2- is replaced with -O-, -C(=O)-, or -OC(=O)-. * represents a bond.

[0036] Examples of the substituent on the ring include a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluoroalkyl group having 1 to 10 carbon atoms, a fluoroalkenyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, a carboxy group, a hydroxy group, an alkyloxycarbonyl group having 1 to 10 carbon atoms, a cyano group, and a nitro group.

[0037] From the viewpoint of improving liquid crystal alignment properties, the divalent organic group represented by the above formula (O) is preferably a divalent organic group represented by the following formulas (o-1) to (o-16).

[0038] [ka]

[0039] [ka]

[0040] [ka] (The "*" in the formula indicates the bond position.)

[0041] From the viewpoint of improving liquid crystal alignment properties, the divalent organic group represented by the above formula (O') is preferably a divalent organic group represented by the above formulas (o-7) to (o-16).

[0042] Preferable specific examples of the diamine represented by the above formula (3i) include the compounds represented by the following formulas (3i-1) to (3i-5).

[0043] [ka]

[0044] The total proportion of the diamine represented by formula (3) and the diamine represented by formula (3i) is preferably 1 to 95 mol%, more preferably 1 to 90 mol%, and even more preferably 5 to 90 mol%, per mol of the diamine component.

[0045] The polyimide polymer used in the present invention may have at least one nitrogen-containing structure (hereinafter also referred to as nitrogen-containing structure) selected from the group consisting of a nitrogen-containing heterocycle (excluding the imide ring of polyimide), a secondary amino group, and a tertiary amino group, from the viewpoint of increasing the voltage retention rate of the resulting liquid crystal alignment film. The polyimide polymer having a nitrogen-containing structure can be obtained by using a monomer having a nitrogen-containing structure, for example, a diamine having a nitrogen-containing structure, as at least a part of the raw material.

[0046] Examples of the nitrogen-containing heterocycle that the diamine having a nitrogen-containing structure may have include pyrrole, imidazole, pyrazole, triazole, pyridine, pyrimidine, pyridazine, pyrazine, indole, benzimidazole, purine, quinoline, isoquinoline, naphthyridine, quinoxaline, phthalazine, triazine, carbazole, acridine, piperidine, piperazine, pyrrolidine, hexamethyleneimine, etc. Among these, pyridine, pyrimidine, pyrazine, piperidine, piperazine, quinoline, carbazole, or acridine is preferred.

[0047] The secondary amino group and tertiary amino group that the diamine having a nitrogen-containing structure may have are represented, for example, by the following formula (n).

[0048] [ka] In the above formula (n), R represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. "*" represents a bond bonded to the hydrocarbon group.

[0049] Examples of the monovalent hydrocarbon group R in the above formula (n) include alkyl groups such as methyl, ethyl, and propyl groups; cycloalkyl groups such as cyclohexyl groups; and aryl groups such as phenyl and methylphenyl groups. R is preferably a hydrogen atom or a methyl group.

[0050] Specific examples of diamines having a nitrogen-containing structure include 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, 1,4-bis-(4-aminophenyl)-piperazine, 3,6-diaminoacridine, N-ethyl-3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, compounds represented by the following formulas (Dp-1) to (Dp-9), and compounds represented by the following formulas (z-1) to (z-18).

[0051] [ka]

[0052] [ka]

[0053] [ka]

[0054] From the viewpoint of increasing the voltage retention rate of the liquid crystal display element, the proportion of the diamine having a nitrogen-containing structure used is preferably 1 mol % or more, more preferably 2 mol % or more, based on the total amount of the diamine used in the synthesis, and the proportion is preferably 90 mol % or less, more preferably 80 mol % or less.

[0055] The polyimide polymer used in the present invention may contain other diamines in addition to the diamines described above. Examples of other diamines are given below, but the present invention is not limited to these. A diamine having 6 to 30 carbon atoms and having a group "-N(D)- (D represents a carbamate-based protecting group)" in the molecule; 4,4'-diaminoazobenzene and the following formula (d T -1)~(d Tdiamines having a photoalignment group such as diamines represented by the formula (I-3); 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminobenzophenone, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(4-amino benzyl)benzene, 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol; 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, 3,5-diaminobenzoic acid, and diamines having a carboxy group such as the diamine compounds represented by the following formulas (3b-1) to (3b-4); 4-(2-(methylamino)ethyl)aniline, 4-(2-aminoethyl)aniline, 4,4'-diaminodiphenylmethane, 4,4'-diamino Benzophenone, 4,4'-diaminodiphenyl ether, 4,4'-diaminobenzanilide, 4,4'-diaminoazobenzene, 1-(4-aminophenyl)-1,3,3-trimethyl-1H-indan-5-amine, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-inden-6-amine; diamines having a urea bond such as diamines represented by the following formulas (h-1) to (h-3); diamines having an amide bond such as diamines represented by the following formulas (h-4) to (h-6); 2-(2,4-diaminophenoxy methacrylate (V) Diamines having a photopolymerizable group at the end, such as ethyl and 2,4-diamino-N,N-diallylaniline; diamines having a steroid skeleton, such as cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, cholestanyl 3,5-diaminobenzoate, lanostannyl 3,5-diaminobenzoate, and 3,6-bis(4-aminobenzoyloxy)cholestane; diamines represented by the following formulas (V-1) to (V-6);Examples of the diamine include diamines having a siloxane bond such as 1,3-bis(3-aminopropyl)-tetramethyldisiloxane; diamines having an oxazoline structure such as those represented by the following formulae (Ox-1) to (Ox-2); and diamines having two amino groups bonded to a group represented by any one of the formulae (Y-1) to (Y-167) described in WO 2018 / 117239.

[0056] [ka]

[0057] [ka] (In formula (3b-1), A 1 represents a single bond, -CH2-, -C2H4-, -C(CH3)2-, -CF2-, -C(CF3)2-, -O-, -CO-, -NH-, -N(CH3)-, -CONH-, -NHCO-, -CHO-, -OCH2-, -COO-, -OCO-, -CON(CH3)- or -N(CH3)CO-; m1 and m2 each independently represent an integer of 0 to 4, and m1+m2 represents an integer of 1 to 4. In formula (3b-2), m3 and m4 each independently represent an integer of 1 to 5. In formula (3b-3), A 2 represents a linear or branched alkyl group having 1 to 5 carbon atoms, and m5 represents an integer of 1 to 5. 3 and A 4 each independently represents a single bond, -CH2-, -C2H4-, -C(CH3)2-, -CF2-, -C(CF3)2-, -O-, -CO-, -NH-, -N(CH3)-, -CONH-, -NHCO-, -CHO-, -OCH2-, -COO-, -OCO-, -CON(CH3)- or -N(CH3)CO-, and m6 represents an integer of 1 to 4.

[0058] [ka]

[0059] [ka] (X v1 ~X v4 , X p1 ~X p2 are each independently -(CH2) a -(a is an integer of 1 to 15), -CONH-, -NHCO-, -CON(CH3)-, -NH-, -O-, -CHO-, -CHOCO-, -COO-, or -OCO-; v5 represents -O-, -CH2O-, -CH2OCO-, -COO-, or -OCO-. X a is a single bond, -O-, -NH-, or -O-(CH2) m -O- (m represents an integer of 1 to 6), R v1 ~R v4 , R 1a ~R 1b each independently represents an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkoxyalkyl group having 2 to 20 carbon atoms.

[0060] [ka]

[0061] Examples of diamines having 6 to 30 carbon atoms and having the above group "-N(D)- (D represents a carbamate protecting group)" in the molecule include compounds represented by the following formulas (5-1) to (5-10).

[0062] [ka] (Boc represents a tert-butoxycarbonyl group.)

[0063] <(B) component> One embodiment of the liquid crystal aligning agent of the present invention is characterized in that it contains a hydroxyalkylamide compound (B) represented by the following formula (1).

[0064] [ka] (R is an alkyl group having 1 to 6 carbon atoms, R1 and R2 each independently represent a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms, and A represents a divalent organic group having 1 to 30 carbon atoms.)

[0065] Examples of the alkyl group having 1 to 6 carbon atoms represented by R in the above formula (1) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, a cyclopentyl group, and a cyclohexyl group.

[0066] Examples of the monovalent organic group having 1 to 6 carbon atoms for R1 and R2 in the above formula (1) include an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, or a heteroatom-containing group containing a group having a heteroatom between the carbon atoms of these groups, and groups in which some or all of the hydrogen atoms of the above alkyl groups, alkenyl groups, alkynyl groups, and heteroatom-containing groups have been substituted with substituents.

[0067] Examples of the group having a hetero atom include groups having at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom, a silicon atom, a phosphorus atom, and a sulfur atom, and include -O-, -NR- (R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms), -CO-, -S-, -CO-, and groups formed by combining these. Of these, -O- is preferred.

[0068] Examples of the substituent include halogen atoms such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom; alkoxy groups such as a methoxy group, an ethoxy group, and a propoxy group; alkoxycarbonyl groups such as a methoxycarbonyl group and an ethoxycarbonyl group; alkoxycarbonyloxy groups such as a methoxycarbonyloxy group and an ethoxycarbonyloxy group; a cyano group, a nitro group, and a hydroxy group.

[0069] From the viewpoint of improving the liquid crystal alignment property, R1 in the above formula (1) is preferably a hydrogen atom or a methyl group, and R2 is preferably a hydrogen atom.

[0070] Examples of the divalent organic group having 1 to 30 carbon atoms for A in the above formula (1) include divalent hydrocarbon groups, divalent heteroatom-containing groups containing a group having the above heteroatom between the carbon atoms of this hydrocarbon group, and divalent organic groups in which some or all of the hydrogen atoms in the above divalent hydrocarbon groups and divalent heteroatom-containing groups have been substituted with the substituents exemplified for R1 and R2 above.

[0071] Examples of the divalent hydrocarbon group include divalent hydrocarbon groups obtained by removing two hydrogen atoms from hydrocarbons such as alkanes having 1 to 30 carbon atoms, such as methane, ethane, propane, and butane; alkenes such as ethylene, propene, butene, and pentene; and alkynes such as ethyne, propyne, butyne, and pentyne; alicyclic hydrocarbons having 3 to 30 carbon atoms, such as cycloalkanes such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, norbornane, and adamantane; cycloalkenes such as cyclopropene, cyclobutene, cyclopentene, cyclohexene, and norbornene; and aromatic hydrocarbons having 6 to 30 carbon atoms, such as benzene, toluene, xylene, mesitylene, arenes such as naphthalene, methylnaphthalene, dimethylnaphthalene, and anthracene.

[0072] In the above formula (1), A is preferably a divalent hydrocarbon group having 1 to 30 carbon atoms, and more preferably a divalent chain hydrocarbon having 1 to 30 carbon atoms, or a divalent hydrocarbon group obtained by removing two hydrogen atoms from an aromatic hydrocarbon having 6 to 30 carbon atoms. The divalent chain hydrocarbon having 1 to 30 carbon atoms is preferably a divalent chain hydrocarbon having 2 to 30 carbon atoms, and more preferably a divalent chain hydrocarbon having 2 to 16 carbon atoms.

[0073] The hydroxyalkylamide compound represented by the above formula (1) is preferably any one of the compounds represented by the following formulas (b-1) to (b-3).

[0074] [ka]

[0075] The content of the hydroxyalkylamide compound represented by the above formula (1) in the liquid crystal aligning agent of the present invention is preferably 0.1 to 50 parts by mass, more preferably 0.1 to 30 parts by mass, relative to 100 parts by mass of the component (A).

[0076] <(B') component> Another embodiment of the liquid crystal aligning agent of the present invention is characterized in that it contains a hydroxyalkylamide compound (B') represented by the following formula (1').

[0077] [ka] (R' is a group "*-C(R 2’ )2-C(R 1’ )2-OH" (* represents a bond. R 1’ , R 2’ each independently represents a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms; R' may be the same or different; and n is an integer of 1 to 30. 1’ is a divalent organic group having 1 to 10 carbon atoms, and multiple L 1’ may be the same or different.)

[0078] R in the above formula (1') 1’ and R 2’ Examples of the monovalent organic group having 1 to 6 carbon atoms include the structures exemplified as R1 and R2 in the above formula (1), and are the same as R1 and R2, including preferred specific examples.

[0079] L in the above formula (1') 1’Examples of the divalent organic group having 1 to 10 carbon atoms include a divalent hydrocarbon group having 1 to 10 carbon atoms, a divalent heteroatom-containing group containing a group having the above-mentioned heteroatom between the carbon atoms of this hydrocarbon group, and a divalent organic group in which some or all of the hydrogen atoms of the above-mentioned divalent hydrocarbon group and divalent heteroatom-containing group are substituted with the substituents exemplified for R1 and R2 in the above formula (1). Specific examples of the divalent hydrocarbon group include the hydrocarbon groups exemplified for A in the above formula (1). L in the above formula (1') 1’ is preferably a divalent hydrocarbon group having 1 to 10 carbon atoms, more preferably a divalent chain hydrocarbon having 1 to 10 carbon atoms, or a divalent hydrocarbon group obtained by removing two hydrogen atoms from an aromatic hydrocarbon having 6 to 10 carbon atoms. The divalent chain hydrocarbon having 1 to 10 carbon atoms is preferably a divalent chain hydrocarbon having 2 to 10 carbon atoms, and more preferably a divalent chain hydrocarbon having 2 to 8 carbon atoms.

[0080] In the above formula (1′), n is more preferably an integer of 1 to 20, and further preferably an integer of 2 to 20.

[0081] The hydroxyalkylamide compound represented by the above formula (1') is preferably any of the compounds represented by the following formulas (b'-1) to (b'-5). [ka]

[0082] The content of the hydroxyalkylamide compound represented by the above formula (1') in the liquid crystal aligning agent of the present invention is preferably 0.1 to 50 parts by mass, more preferably 0.1 to 30 parts by mass, relative to 100 parts by mass of the component (A').

[0083] <Method of producing polyamic acid> The polyamic acid, which is a polyimide precursor used in the present invention, can be produced by the following method. Specifically, it can be synthesized by reacting (polycondensation reaction) the above tetracarboxylic acid component and the above diamine component in the presence of an organic solvent at -20 to 150°C, preferably 0 to 50°C, for 30 minutes to 24 hours, preferably 1 to 12 hours. Specific examples of organic solvents used in the above reaction include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, and 1,3-dimethyl-2-imidazolidinone. In addition, when the polymer has high solubility in the solvent, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or solvents represented by the following formulas [D-1] to [D-3] can be used. These may be used in combination of two or more kinds.

[0084] [ka] (In formula [D-1], D 1 represents an alkyl group having 1 to 3 carbon atoms, and in formula [D-2], D 2 represents an alkyl group having 1 to 3 carbon atoms, and in formula [D-3], D 3 represents an alkyl group having 1 to 4 carbon atoms.

[0085] The reaction can be carried out at any concentration, but is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The reaction can be carried out at a high concentration in the early stages, and then a solvent can be added. In the reaction, the ratio of the total number of moles of the diamine components to the total number of moles of the tetracarboxylic acid components is preferably 0.8 to 1.2. As in the case of a normal polycondensation reaction, the closer this molar ratio is to 1.0, the higher the molecular weight of the polyamic acid produced.

[0086] The polyamic acid obtained by the above reaction can be precipitated and collected by injecting the reaction solution into a poor solvent while thoroughly stirring it. In addition, the precipitation can be carried out several times, washed with a poor solvent, and then dried at room temperature or by heating to obtain a purified polyamic acid powder. The poor solvent is not particularly limited, but examples thereof include water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

[0087] When the polyimide precursor is a polyamic acid ester, it can be produced by known methods such as (1) a method of esterifying a polyamic acid obtained from a tetracarboxylic dianhydride and a diamine, (2) a method of reacting a tetracarboxylic diester dichloride with a diamine, or (3) a method of polycondensing a tetracarboxylic diester with a diamine.

[0088] The polyimide precursor may be a terminal-modified polymer obtained by using an appropriate terminal-capping agent together with the above-mentioned tetracarboxylic acid derivative and diamine during the production thereof. Examples of the terminal modifier include acid anhydrides such as acetic anhydride, maleic anhydride, nadic anhydride, phthalic anhydride, itaconic anhydride, cyclohexanedicarboxylic anhydride, 3-hydroxyphthalic anhydride, and trimellitic anhydride; di-tert-butyl dicarbonate; monoamine compounds such as aniline, 2-aminophenol, 3-aminophenol, 4-aminosalicylic acid, 5-aminosalicylic acid, 6-aminosalicylic acid, 2-aminobenzoic acid, 3-aminobenzoic acid, and 4-aminobenzoic acid; and monoisocyanate compounds such as ethyl isocyanate, phenyl isocyanate, and naphthyl isocyanate. The proportion of the terminal modifier used is preferably 40 parts by mol or less, and more preferably 30 parts by mol or less, per 100 parts by mol of the total of the diamine components used.

[0089] <Polyimide manufacturing method> The polyimide used in the present invention can be produced by imidizing a polyimide precursor, a polyamic acid or a polyamic acid ester, by a known method. In polyimide, the ring closure rate (also called imidization rate) of the functional group of the polyamic acid or polyamic acid ester does not necessarily need to be 100% and can be arbitrarily adjusted depending on the application or purpose.

[0090] The method of obtaining a polyimide by imidizing the polyamic acid or polyamic acid ester includes thermal imidization in which a solution of the polyamic acid or polyamic acid ester is heated as is, or catalytic imidization in which a catalyst is added to a solution of the polyamic acid or polyamic acid ester. The temperature for thermal imidization is 100 to 400°C, preferably 120 to 250°C, and it is preferable to carry out the imidization while removing water generated by the imidization reaction from the system.

[0091] Catalytic imidization can be carried out by adding a basic catalyst and an acid anhydride to a polymer solution and stirring at -20 to 250°C, preferably 0 to 180°C. The amount of the basic catalyst is 0.5 to 30 times by mol, preferably 2 to 20 times by mol, the amount of the amic acid group or amic acid ester group, and the amount of the acid anhydride is 1 to 50 times by mol, preferably 3 to 30 times by mol, the amount of the amic acid group or amic acid ester group. Examples of basic catalysts include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, etc., and among these, pyridine is preferred because it has a suitable basicity for promoting the reaction. Examples of acid anhydrides include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, etc., and among these, acetic anhydride is preferred because it makes purification after the reaction easy. The imidization rate by catalytic imidization can be controlled by adjusting the amount of catalyst, reaction temperature, and reaction time.

[0092] When recovering the polyimide produced from the reaction solution of catalytic imidization, the reaction solution may be poured into a solvent to cause precipitation. Examples of the solvent used for precipitation include methanol, ethanol, isopropyl alcohol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, toluene, benzene, and water. The polymer precipitated by pouring into the solvent can be recovered by filtration, and then dried at room temperature or by heating under normal or reduced pressure. In addition, the polymer precipitated and recovered can be redissolved in a solvent and the reprecipitation and recovery operation can be repeated 2 to 10 times to reduce impurities in the polymer. Examples of the solvent used in this case include alcohols, ketones, and hydrocarbons, and it is preferable to use three or more solvents selected from these because the efficiency of purification is further improved.

[0093] <Polymer solution viscosity and molecular weight> The polyamic acid, polyamic acid ester, and polyimide used in the present invention preferably have a solution viscosity of, for example, 10 to 1000 mPa·s when made into a solution of 10 to 15% by mass from the viewpoint of workability, but are not particularly limited thereto. The solution viscosity (mPa·s) of the above polymer is a value measured at 25°C using an E-type rotational viscometer for a polymer solution of 10 to 15% by mass prepared using a good solvent for the polymer (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

[0094] The polystyrene-equivalent weight average molecular weight (Mw) of the polyamic acid, polyamic acid ester, and polyimide measured by gel permeation chromatography (GPC) is preferably 1,000 to 500,000, and more preferably 2,000 to 500,000. The molecular weight distribution (Mw / Mn), which is expressed as the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) measured by GPC, is preferably 15 or less, and more preferably 10 or less. With the molecular weight in this range, good liquid crystal alignment properties can be ensured in the liquid crystal display element.

[0095] <Preferred embodiment of liquid crystal alignment agent> A preferred embodiment of the liquid crystal alignment agent of the present invention is, for example, a form in which a hydroxyalkylamide compound of the above formula (1) or (1') is added to a solution in which a polymer capable of aligning liquid crystals is dissolved in a solvent. The content (concentration) of the polymer contained in the liquid crystal alignment agent of the present invention can be appropriately changed depending on the thickness of the coating film to be formed, but it is preferably 1% by mass or more from the viewpoint of forming a uniform and defect-free coating film, and is preferably 10% by mass or less from the viewpoint of storage stability of the solution. The content of the hydroxyalkylamide compound of the above formula (1) or (1') is preferably 1 to 15 mass %, more preferably 2 to 10 mass %, and particularly preferably 2 to 8 mass %, based on the total content of the polymer and the hydroxyalkylamide compound of the above formula (1) or (1') contained in the liquid crystal alignment agent.

[0096] The solvent contained in the liquid crystal alignment agent is not particularly limited as long as the polymer component is uniformly dissolved in the solvent. Specific examples thereof include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyllactamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylsulfoxide, γ-butyrolactone, γ-valerolactone, 1,3-dimethyl-2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, 3-methyl ... Examples of the good solvent include N-propanamide, N-(n-propyl)-2-pyrrolidone, N-isopropyl-2-pyrrolidone, N-(n-butyl)-2-pyrrolidone, N-(tert-butyl)-2-pyrrolidone, N-(n-pentyl)-2-pyrrolidone, N-methoxypropyl-2-pyrrolidone, N-ethoxyethyl-2-pyrrolidone, N-methoxybutyl-2-pyrrolidone, and N-cyclohexyl-2-pyrrolidone (collectively referred to as "good solvent"). Among these, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, and γ-butyrolactone are preferred. The content of the good solvent is preferably 20 to 99% by mass, more preferably 20 to 90% by mass, and particularly preferably 30 to 80% by mass of the total solvent contained in the liquid crystal alignment agent.

[0097] In addition, the solvent contained in the liquid crystal alignment agent is preferably a mixed solvent containing the above-mentioned solvent and a solvent (also called a poor solvent) that improves the coating property when applying the liquid crystal alignment agent and the surface smoothness of the coating film. Specific examples of the solvent to be used in combination are shown below, but are not limited thereto.

[0098] For example, diisopropyl ether, diisobutyl ether, diisobutyl carbinol (2,6-dimethyl-4-heptanol), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, propylene glycol monobutyl ether, 1-(2-butoxyethoxy)-2-propanol, Examples of the esters include 2-(2-butoxyethoxy)-1-propanol, propylene glycol monomethyl ether acetate, propylene glycol diacetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethylene glycol acetate, propylene glycol diacetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, n-butyl lactate, isoamyl lactate, diethylene glycol monoethyl ether, and diisobutyl ketone (2,6-dimethyl-4-heptanone). The content of the poor solvent is preferably from 1 to 80 mass %, more preferably from 10 to 80 mass %, particularly preferably from 20 to 70 mass %, of the total solvent contained in the liquid crystal aligning agent.The type and content of the poor solvent are appropriately selected depending on the coating device, coating conditions, coating environment, etc. of the liquid crystal alignment agent.

[0099] Of these, diisobutyl carbinol, propylene glycol monobutyl ether, propylene glycol diacetate, diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, or diisobutyl ketone is preferred.

[0100] Preferred combinations of good and poor solvents include N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone, and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone, and propylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone, and diethylene glycol diethyl ether, and N-methyl-2-pyrrolidone and γ- butyrolactone, propylene glycol monobutyl ether, and diisobutyl ketone, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisopropyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisobutyl carbinol, N-methyl-2-pyrrolidone, γ-butyrolactone, and dipropylene glycol dimethyl ether, and N-methyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol dimethyl ether.

[0101] The liquid crystal alignment agent of the present invention may additionally contain components other than the polymer component and the solvent (hereinafter also referred to as additive components). Examples of such additive components include adhesion assistants for increasing the adhesion between the liquid crystal alignment film and the substrate or between the liquid crystal alignment film and the sealant, compounds for increasing the strength of the liquid crystal alignment film (hereinafter also referred to as crosslinking compounds), and dielectrics and conductive substances for adjusting the dielectric constant and electrical resistance of the liquid crystal alignment film.

[0102] Examples of the crosslinkable compound include, from the viewpoint of exhibiting good resistance to AC afterimages and highly improving film strength, compounds having at least one group selected from the group consisting of an oxiranyl group, an oxetanyl group, a protected isocyanate group, a protected isothiocyanate group, a group containing an oxazoline ring structure, a group containing a Meldrum's acid structure, and a cyclocarbonate group; hydroxyalkylamide compounds other than the compounds represented by the above formulas (1) and (1'); and compounds selected from compounds represented by the following formula (e).

[0103] [ka] (A represents an (m+n)-valent organic group having an aromatic ring. m represents an integer of 1 to 6, and n represents an integer of 0 to 4. R e , R f each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkynyl group having 2 to 6 carbon atoms. The aromatic ring of A may be substituted with a monovalent group, and specific examples of the monovalent group include the monovalent organic groups shown as the substituents of Ar in the above formula (O) (however, excluding alkoxy groups having 1 to 10 carbon atoms).

[0104] Specific examples of the compound having an oxiranyl group include compounds having two or more oxiranyl groups, such as the compounds described in paragraph

[0037] of JP-A-10-338880 and compounds having a triazine ring skeleton described in WO 2017 / 170483. Among these, compounds containing nitrogen atoms, such as N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, N,N,N',N'-tetraglycidyl-p-phenylenediamine, and compounds represented by the following formulas (r-1) to (r-3), may be used.

[0105] [ka]

[0106] Specific examples of the compound having an oxetanyl group include compounds having two or more oxetanyl groups described in paragraphs

[0170] to

[0175] of WO 2011 / 132751.

[0107] Specific examples of the compound having a protected isocyanate group include the compound having two or more protected isocyanate groups described in paragraphs

[0046] to

[0047] of JP 2014-224978 A, and the compound having three or more protected isocyanate groups described in paragraphs

[0119] to

[0120] of WO 2015 / 141598 A. The compound may be any of the compounds represented by the following formulae (bi-1) to (bi-3).

[0108] [ka]

[0109] Specific examples of compounds having a protected isothiocyanate group include compounds having two or more protected isothiocyanate groups described in JP 2016-200798 A.

[0110] Specific examples of the compound having a group containing an oxazoline ring structure include compounds containing two or more oxazoline structures described in paragraph

[0115] of JP 2007-286597 A.

[0111] Specific examples of the compound having a group containing a Meldrum's acid structure include compounds having two or more Meldrum's acid structures described in WO 2012 / 091088.

[0112] Specific examples of the compound having a cyclocarbonate group include the compounds described in WO 2011 / 155577.

[0113] Specific examples of hydroxyalkylamide compounds other than the compounds represented by the above formulas (1) and (1') include compounds described in WO 2015 / 072554, JP 2016-118753 A, paragraph

[0058] , compounds described in JP 2016-200798 A, and compounds described in WO 2019 / 142927, and may also be compounds represented by the following formulas (hd-1) to (hd-8), and compounds represented by the following formulas (hd1-1) to (hd1-4).

[0114] [ka]

[0115] [ka]

[0116] Examples of the (m+n)-valent organic group having an aromatic ring in A of the above formula (e) include an (m+n)-valent aromatic hydrocarbon group having 6 to 30 carbon atoms, an (m+n)-valent organic group to which an aromatic hydrocarbon group having 6 to 30 carbon atoms is bonded directly or via a linking group, and an (m+n)-valent group having an aromatic heterocycle. Examples of the aromatic hydrocarbon include benzene and naphthalene. Examples of the aromatic heterocycle include a pyrrole ring, an imidazole ring, a pyrazole ring, a pyridine ring, a pyrimidine ring, a quinoline ring, an isoquinoline ring, a carbazole ring, a pyridazine ring, a pyrazine ring, a benzimidazole ring, an indole ring, a quinoxaline ring, and an acridine ring. Examples of the linking group include an alkylene group having 1 to 10 carbon atoms, -NR- (R is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms), an alkylene group having 1 to 10 carbon atoms and a fluorine atom, or a group in which one hydrogen atom has been removed from the alkylene group, and a divalent or trivalent cyclohexane ring. Any hydrogen atom in the alkylene group may be substituted with a fluorine atom or an organic group such as a trifluoromethyl group. Specific examples include the compounds described in WO 2010 / 074269 and the compounds represented by the following formulas (e-1) to (e-10).

[0117] [ka]

[0118] The above compounds are examples of crosslinkable compounds, and are not limited thereto. For example, components other than those described above are disclosed on pages 53

[0105] to 55

[0116] of International Publication No. 2015 / 060357. In addition, two or more types of crosslinkable compounds may be combined.

[0119] The content of the crosslinkable compound in the liquid crystal aligning agent of the present invention is preferably 0.5 to 20 parts by mass relative to 100 parts by mass of the polymer component contained in the liquid crystal aligning agent, and from the viewpoint of proceeding with the crosslinking reaction and exhibiting good resistance to AC afterimages, it is more preferably 1 to 15 parts by mass.

[0120] Examples of the adhesion aid include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxy ... triethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis(oxyethylene)-3-aminopropyltrimethoxysilane, N-bis(oxyethylene)-3-aminopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,Examples of silane coupling agents include 4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, tris-(trimethoxysilylpropyl)isocyanurate, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-isocyanatepropyltriethoxysilane. When a silane coupling agent is used, the amount is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, per 100 parts by mass of the polymer component contained in the liquid crystal alignment agent, from the viewpoint of exhibiting good resistance to AC afterimages.

[0121] (Liquid crystal alignment film) The liquid crystal alignment film of the present invention is formed using the liquid crystal aligning agent of the present invention. A preferred embodiment of the method for producing a liquid crystal alignment film of the present invention includes, for example, a step of applying the above-mentioned liquid crystal alignment agent to a substrate (step (1)), a step of baking the applied liquid crystal alignment agent (step (2)), and, in some cases, a step of performing an alignment treatment on the film obtained in step (2) (step (3)).

[0122] <Process (1)> The substrate to which the liquid crystal alignment agent used in the present invention is applied is not particularly limited as long as it is a highly transparent substrate, and a glass substrate, a silicon nitride substrate, a plastic substrate such as an acrylic substrate or a polycarbonate substrate, etc. can also be used. In this case, it is preferable to use a substrate on which an ITO electrode for driving the liquid crystal is formed from the viewpoint of simplifying the process. In addition, in a reflective liquid crystal display element, an opaque material such as a silicon wafer can be used for only one substrate, and in this case, a light-reflecting material such as aluminum can be used for the electrode.

[0123] Examples of the method for applying the liquid crystal alignment agent to a substrate and forming a film include screen printing, offset printing, flexographic printing, an inkjet method, a spray method, etc. Among these, the application and film formation method by the inkjet method is preferably used.

[0124] <Process (2)> Step (2) is a step of baking the liquid crystal alignment agent applied on the substrate to form a film. After the liquid crystal alignment agent is applied on the substrate, the solvent can be evaporated or the amic acid or amic acid ester in the polymer can be thermally imidized by a heating means such as a hot plate, a heat circulation type oven, or an IR (infrared) type oven. The drying and baking steps after the application of the liquid crystal alignment agent of the present invention can be performed at any temperature and time, and may be performed multiple times. The temperature for evaporating the solvent of the liquid crystal alignment agent can be, for example, 40 to 180°C. From the viewpoint of shortening the process, it may be performed at 40 to 150°C. The baking time is not particularly limited, but may be 1 to 10 minutes or 1 to 5 minutes. When the amic acid or amic acid ester in the polymer is thermally imidized, a baking step can be performed at a temperature range of, for example, 150 to 300°C or 150 to 250°C after the step of evaporating the organic solvent. The baking time is not particularly limited, but may be 5 to 40 minutes, or 5 to 30 minutes. If the film-like material after firing is too thin, the reliability of the liquid crystal display element may decrease, so the thickness is preferably 5 to 300 nm, and more preferably 10 to 200 nm.

[0125] <Process (3)> Step (3) is a step of subjecting the film obtained in step (2) to an alignment treatment, if necessary. That is, in a vertical alignment type liquid crystal display element such as a VA mode or PSA mode, the formed coating film can be used as a liquid crystal alignment film as it is, but the coating film may be subjected to an alignment ability imparting treatment. The alignment treatment method for the liquid crystal alignment film may be a rubbing treatment method, but a photo-alignment treatment method is preferable. As the photo-alignment treatment method, a method in which the surface of the above-mentioned film-like material is irradiated with radiation deflected in a certain direction, and, if necessary, a heat treatment is performed at a temperature preferably of 150 to 250°C to impart liquid crystal alignment property (also called liquid crystal alignment ability) can be mentioned. As the radiation, ultraviolet rays or visible light having a wavelength of 100 to 800 nm can be used. Among them, ultraviolet rays having a wavelength of 100 to 400 nm are preferable, and more preferably, ultraviolet rays having a wavelength of 200 to 400 nm are more preferable.

[0126] The radiation dose is 1 to 10,000 mJ / cm 2 Among them, 100 to 5,000 mJ / cm is preferable. 2 In addition, when irradiating with radiation, the substrate having the film-like material may be irradiated while being heated at 50 to 250° C. in order to improve the liquid crystal alignment. The liquid crystal alignment film thus produced can stably align liquid crystal molecules in a certain direction. Furthermore, the liquid crystal alignment film irradiated with polarized radiation by the above method can be contacted with water or a solvent, or the liquid crystal alignment film irradiated with radiation can be heat-treated.

[0127] The solvent used in the contact treatment is not particularly limited as long as it dissolves the decomposition product generated from the film-like material by irradiation with radiation. Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, cyclohexyl acetate, and the like. Among these, water, 2-propanol, 1-methoxy-2-propanol, or ethyl lactate is preferred from the viewpoint of versatility and solvent safety. Water, 1-methoxy-2-propanol, or ethyl lactate is more preferred. The solvent may be one type or a combination of two or more types.

[0128] The contact treatment includes immersion treatment and spray treatment (also called spray treatment). The treatment time in these treatments is preferably 10 seconds to 1 hour from the viewpoint of efficiently dissolving the decomposition products generated from the film-like material by irradiation with radiation. In particular, immersion treatment for 1 to 30 minutes is preferred. The solvent during the contact treatment may be at room temperature or heated, preferably 10 to 80°C. In particular, 20 to 50°C is preferred. In addition, from the viewpoint of the solubility of the decomposition products, ultrasonic treatment or the like may be performed as necessary.

[0129] After the contact treatment, it is preferable to perform rinsing (also called rinsing) with a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, etc., and calcination. In this case, either rinsing or calcination may be performed, or both may be performed. The calcination temperature is preferably 150 to 300°C. Of these, 180 to 250°C is preferable, and 200 to 230°C is more preferable. The calcination time is preferably 10 seconds to 30 minutes, and of these, 1 to 10 minutes is preferable. The heat treatment of the coating film irradiated with the above-mentioned radiation is more preferably carried out at 50 to 300° C. for 1 to 30 minutes, and even more preferably at 120 to 250° C. for 1 to 30 minutes.

[0130] (Liquid crystal display element) The liquid crystal display element of the present invention has the liquid crystal alignment film of the present invention. The liquid crystal alignment film of the present invention is suitable as a liquid crystal alignment film for in-plane switching mode liquid crystal display elements such as IPS mode and FFS mode, from the viewpoint of obtaining high liquid crystal alignment properties, and is particularly useful as a liquid crystal alignment film for FFS mode liquid crystal display elements. A liquid crystal display element can be manufactured by obtaining a substrate with a liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention, preparing a liquid crystal cell by a known method, and disposing liquid crystal in the liquid crystal cell. Specifically, the following two methods can be mentioned. In the first method, first, two substrates are arranged opposite each other with a gap (cell gap) so that the liquid crystal alignment films face each other. Next, the peripheries of the two substrates are bonded together using a sealant, and a liquid crystal composition is injected and filled into the substrate surfaces and the cell gap partitioned by the sealant so that it comes into contact with the film surface, and then the injection hole is sealed.

[0131] The second method is a technique called the ODF (One Drop Fill) method. For example, a UV-curable sealant is applied to a predetermined location on one of the two substrates on which a liquid crystal alignment film is formed, and a liquid crystal composition is dropped at several predetermined locations on the liquid crystal alignment film surface. Thereafter, the other substrate is bonded so that the liquid crystal alignment film faces the other substrate, and the liquid crystal composition is spread over the entire surface of the substrate and contacted with the film surface. Next, the entire surface of the substrate is irradiated with UV light to cure the sealant. In either method, it is preferable to further remove the flow alignment during liquid crystal filling by heating to a temperature at which the liquid crystal composition used has an isotropic phase and then slowly cooling to room temperature. When the coating film is subjected to a rubbing treatment, the two substrates are arranged to face each other so that the rubbing directions of the coating films are at a predetermined angle, for example, perpendicular or anti-parallel. Similarly, when the photo-alignment treatment is performed, the substrates are arranged to face each other so that the alignment directions are at a predetermined angle, for example, perpendicular or anti-parallel. The sealing agent may be, for example, an epoxy resin containing a hardener and aluminum oxide spheres as spacers. The liquid crystal may be a nematic liquid crystal or a smectic liquid crystal, of which the nematic liquid crystal is preferred.

[0132] The liquid crystal material may be either a positive type or a negative type, but a negative type is preferred. Next, polarizing plates are installed. Specifically, a pair of polarizing plates are attached to the surfaces of the two substrates opposite the liquid crystal layers. Examples of polarizing plates include a polarizing film called an "H film" made by absorbing iodine while stretching and aligning polyvinyl alcohol, sandwiched between cellulose acetate protective films, and a polarizing plate made of the H film itself. EXAMPLES

[0133] The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto. The abbreviations of the compounds and the methods for measuring the respective properties are as follows. In addition, "Boc" represents a tert-butoxycarbonyl group.

[0134] (Organic solvent) NMP: N-methyl-2-pyrrolidone GBL: γ-butyl lactone BCS: Butyl cellosolve DMF: N,N-dimethylformamide

[0135] (Diamine) DA-1 to DA-6: Compounds represented by the following formulas (DA-1) to (DA-6), respectively.

[0136] (Tetracarboxylic acid dianhydride) DAH-1 to DAH-2: Compounds represented by the following formulas (DAH-1) to (DAH-2), respectively.

[0137] (Crosslinking agent) AD-1: A compound represented by the following formula (AD-1): AD-2: A compound represented by the following formula (AD-2). This compound was synthesized by the synthesis method described in Japanese Patent Publication No. 2018-537481 (paragraphs

[0079] to

[0080] , Figure 5). AD-3: A compound represented by the following formula (AD-3).

[0138] [ka]

[0139] [ka]

[0140] [ka]

[0141] [viscosity] The viscosity of the polyamic acid solution was measured using an E-type viscometer (Toki Sangyo Co., Ltd., TVE-22H) with a sample amount of 1.1 mL, a cone rotor TE-1 (1°34′, R24), and a temperature of 25°C.

[0142] [Synthesis of Monomer] The synthesis method of the novel compound AD-3 is described in detail below.

[0143] The product described in Synthesis Example 1 below is 1 The product was identified by H-NMR analysis (analysis conditions are as follows). Equipment:BRUKER ADVANCE III-500MHz Measurement solvent: deuterated dimethyl sulfoxide (DMSO-d6) Reference material: Tetramethylsilane (TMS) (δ0.0 ppm for 1 H)

[0144] (Synthesis Example 1: Synthesis of AD-3) AD-3 was synthesized according to the following scheme.

[0145] [ka]

[0146] <Synthesis of AD-3-1> To tetraethylene glycol (10.0 g, 51.5 mmol), succinic anhydride (13.0 g, 130 mmol), dichloromethane (60 g), and 4-dimethylaminopyridine (3.14 g, 25.7 mmol) were added, and the mixture was heated to reflux at 50 °C for 6 hours. After completion of the reaction, the mixture was cooled to room temperature (25 °C), washed twice by liquid separation with 2 N hydrochloric acid (60 g), concentrated, and dried to obtain AD-3-1 (yield: 15.6 g, 39.6 mmol, yield 77%). 1 1H-NMR (500 MHz) in DMSO-d6: 12.20 (br, 2H), 4.12 (t, 4H), 3.59 (t, 4H), 3.53 (s, 8H), 2.51 (t, 4H), 2.47 (t, 4H).

[0147] <Synthesis of AD-3-2> To AD-3-1 (15.6 g, 39.6 mmol), dichloromethane (94 g), oxalyl chloride (10.4 g, 81.9 mmol), and DMF (0.16 g) were added, and the mixture was stirred at room temperature (25 °C) for 5 hours. After completion of the reaction, the solution was concentrated to obtain the crude product of AD-3-2 (yield: 18 g). The obtained crude product of AD-3-2 was used as it was in the next step.

[0148] <Synthesis of AD-3> To bis(2-((trimethylsilyl)oxy)ethyl)amine (20.8 g, 83.3 mmol), dichloromethane (86 g) and triethylamine (8.82 g, 87.2 mmol) were added, and the mixture was cooled to 0°C in an ice bath. The crude AD-3-2 (18 g) diluted with dichloromethane (34 g) was added dropwise, and the mixture was stirred at room temperature of 25°C for 17 hours after the dropwise addition. The precipitated triethylamine hydrochloride was removed by filtration, and water was added, which emulsified and significantly deteriorated the liquid separation property, so the mixture was concentrated including the aqueous phase. When methanol was added to the crude, the target substance dissolved and salt precipitated, so the mixture was filtered and concentrated. This was repeated three times, and the salt was removed by filtration. Methanol (108 g) was added to the crude, and acetic acid (0.030 g) was added, and the mixture was heated and stirred at 80°C for 2 hours. After confirming the removal of the trimethylsilyl group, the reaction solution was concentrated. Methanol was added and azeotropy was repeated to remove acetic acid, after which acetonitrile and specially made Shirasagi activated carbon were added and heated and stirred at 80°C, after which it was filtered and concentrated. This was repeated twice and dried to obtain AD-3 (yield: 13.1g, 23.0mmol, 2-stage yield 58%). 1 H-NMR(500MHz)in DMSO-d6:4.98(br,4H),4.12(t,4H),3.59(t,4H),3.57-3.43(m,12H),3.41-3.38(m,8H),3.32(t,4H),2.69-2.61(m,4H),2.53-2.49(m,4H).

[0149] [Polymer synthesis] (Production Example 1) DA-1 (1.08g, 10mmol), DA-2 (3.66g, 15mmol), DA-3 (4.81g, 15mmol) and DA-4 (3.98g, 10mmol) were added to a 200mL four-neck flask equipped with a stirrer and nitrogen inlet tube, then NMP (132g) was added and dissolved by stirring while feeding nitrogen. DAH-1 (10.54g, 47mmol) was added to this diamine solution while stirring, and NMP (40.3g) was added, and the mixture was further stirred at 40℃ for 12 hours to obtain a polyamic acid solution (PAA-1) with a solids concentration of 12% by mass. The viscosity of this polyamic acid solution was 430mPa·s.

[0150] (Production Example 2) DA-5 (3.99 g, 20 mmol) and DA-6 (1.49 g, 5.0 mmol) were weighed into a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, then 49 g of NMP was added and dissolved by stirring while supplying nitrogen. DAH-2 (4.71 g, 24 mmol) was added to this diamine solution while stirring, and NMP was further added so that the solid concentration became 10 mass%, and the mixture was stirred at room temperature for 20 hours to obtain a polyamic acid solution (PAA-2) (viscosity: 150 mPa s).

[0151] [Preparation of sample solution] Comparative Example 1 The polyamic acid solution (PAA-1) (1.33 g) obtained in Production Example 1 was weighed out into a 50 mL Erlenmeyer flask containing a stirrer, and the polyamic acid solution (PAA-2) (2.40 g) obtained in Production Example 2 was added. NMP (0.27 g), GBL (2.20 g), BCS (3.00 g), and a 10% NMP solution of AD-1 (0.80 g) were further added, and the mixture was stirred overnight with a magnetic stirrer to obtain a liquid crystal alignment agent (AL-1).

[0152] (Examples 1 to 2) Liquid crystal aligning agents (AL-2) to (AL-3) were obtained by carrying out the same operation as in Comparative Example 1, except that AD-2 to AD-3 were used instead of AD-1.

[0153] Comparative Example 2 A 10% NMP solution (1.20 g) of AD-1 was added to a 50 mL Erlenmeyer flask containing a stirrer, and then NMP (2.80 g), GBL (3.00 g), and BCS (3.00 g) were added, followed by stirring overnight with a magnetic stirrer to obtain a solution (Sol-1).

[0154] (Examples 3 to 4) Solutions (Sol-2) to (Sol-3) were obtained by carrying out the same operation as in Comparative Example 2, except that AD-2 to AD-3 were used instead of AD-1.

[0155] [Evaluation of liquid crystal alignment agents] The liquid crystal alignment films formed using the liquid crystal aligning agents of Comparative Example 1 and Examples 1 and 2, and the liquid crystal elements having the liquid crystal alignment films, were subjected to the afterimage evaluation and rubbing resistance test described below.

[0156] <Preparation of liquid crystal cell> A liquid crystal cell having the structure of an FFS mode liquid crystal display element was fabricated. First, a substrate with electrodes was prepared. The substrate was a rectangular glass substrate measuring 30 mm x 35 mm and 0.7 mm thick. An ITO electrode with a solid pattern was formed on the substrate as the first layer, which constituted the counter electrode, and a SiN (silicon nitride) film formed by CVD was formed on the first layer of the counter electrode as the second layer. The second layer of SiN film had a thickness of 500 nm, which functioned as an interlayer insulating film. A comb-shaped pixel electrode formed by patterning an ITO film was arranged on the second layer of SiN film, which formed two pixels, a first pixel and a second pixel. The size of each pixel was 10 mm long and about 5 mm wide. At this time, the first layer of the counter electrode and the third layer of the pixel electrode were electrically insulated by the action of the second layer of SiN film.

[0157] The pixel electrode in the third layer had a comb-like shape in which multiple 3 μm-wide electrode elements, with the central portion bent at an internal angle of 160°, were arranged in parallel with each other at 6 μm intervals, and each pixel had a first region and a second region, separated by a line connecting the bent portions of the multiple electrode elements.

[0158] Next, the liquid crystal alignment agents (AL-1) to (AL-3) obtained in Comparative Example 1 and Examples 1 to 2 were filtered through a filter with a pore size of 1.0 μm, and then applied by spin coating to the above-prepared electrode-attached substrate and a glass substrate having a columnar spacer with a height of 4 μm and an ITO film formed on the back surface. After drying for 2 minutes on a hot plate at 80°C, the substrate was baked for 30 minutes at 230°C in an IR oven to form a coating film with a thickness of 100 nm. Polarized ultraviolet light was irradiated on the coating surface at 300 mJ / cm. 2The substrate was irradiated with light so that the alignment was performed. The substrate was baked again at 230°C for 30 minutes using an IR oven to obtain a substrate with a liquid crystal alignment film. The above two substrates were combined into a set, and a sealant (Mitsui Chemicals XN-1500T) was printed around the periphery, leaving a liquid crystal injection port, and the other substrate was attached so that the alignment direction of the liquid crystal alignment film faces each other was 0°. The sealant was then cured to produce an empty cell. Liquid crystal MLC-3019 (Merck) was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an FFS drive liquid crystal cell. The FFS driving liquid crystal cell obtained as described above was heated at 110° C. for 1 hour and then allowed to stand overnight, and the following afterimage evaluation was performed.

[0159] <Evaluation of image lag due to long-term AC drive> An AC voltage of ±5V at a frequency of 30Hz was applied to the FFS-driven liquid crystal cell for 120 hours in a constant temperature environment of 60°C (hereinafter, the "FFS-driven liquid crystal cell" is also referred to as the "liquid crystal cell"). After that, the pixel electrode and the counter electrode of the liquid crystal cell were shorted, and the liquid crystal cell was left at room temperature for one day. After leaving it, the liquid crystal cell was placed between two polarizing plates arranged so that the polarization axes were perpendicular to each other, and the backlight was turned on with no voltage applied, and the arrangement angle of the liquid crystal cell was adjusted so that the brightness of the transmitted light was minimized. Then, the rotation angle when the liquid crystal cell was rotated from the angle at which the second region of the first pixel was the darkest to the angle at which the first region was the darkest was calculated as the angle Δ. Similarly, the second region and the first region of the second pixel were compared, and the same angle Δ was calculated. Then, the average value of the angles Δ of the first pixel and the second pixel was calculated as the angle Δ of the liquid crystal cell. The liquid crystal cell obtained above was evaluated as "x" when the angle Δ was 0.10° or more, and as "good" when it was less than 0.10°.

[0160] <Rubbing resistance test> Next, in order to confirm the strength of the liquid crystal alignment films formed using the liquid crystal alignment agents obtained in Examples 1 and 2 and Comparative Example 1, a rubbing resistance test was carried out. The liquid crystal alignment agents (AL-1) to (AL-3) obtained in Comparative Example 1 and Examples 1 and 2 were applied by spin coating to the ITO surface of a glass substrate having an ITO electrode on the entire surface. After drying for 2 minutes on a hot plate at 80°C, the substrate was baked for 30 minutes at 230°C in an IR oven to form a coating film with a thickness of 100 nm. Polarized ultraviolet light was irradiated on the coating surface at 300 mJ / cm. 2 The substrate was then irradiated with light so as to obtain an alignment treatment, and baked again at 230° C. for 30 minutes in an IR oven to obtain a substrate with a liquid crystal alignment film. The substrate with the liquid crystal alignment film obtained as described above was rubbed with a rayon cloth (roller diameter: 120 mm, roller rotation speed: 1000 rpm, moving speed: 20 mm / sec, indentation length: 0.6 mm) and then observed under a microscope to evaluate the rubbing resistance of the liquid crystal alignment film. The samples in which no rubbing streaks were observed on the film surface were rated as "good", and the samples in which streaks were observed were rated as "poor".

[0161] The evaluation results of the afterimage evaluation for the FFS driving liquid crystal cells in Comparative Example 1 and Examples 1 and 2, and the evaluation results of the rubbing resistance test for the liquid crystal alignment films are shown in Table 1 below.

[0162] [Table 1]

[0163] In order to confirm whether the liquid crystal alignment agent is one that does not precipitate solids during low-temperature storage, the following low-temperature storage stability test was carried out using the crosslinker solutions (Sol-1) to (Sol-3) of Comparative Example 2 and Examples 3 to 4.

[0164] <Low temperature storage stability test> The crosslinking agent solutions (Sol-1) to (Sol-3) obtained in Comparative Example 2 and Examples 3 to 4 were left to stand at −20° C. for 2 days to carry out a test for evaluating low-temperature storage stability. The state of precipitation in the solution was observed after two days had passed. If no precipitation was observed, it was judged that the low-temperature storage stability was good for practical use and was rated as "○". On the other hand, if precipitation was observed, it was judged that the low-temperature storage stability was poor and was rated as "×". The results are shown in Table 2 below.

[0165] [Table 2] As shown in Tables 1 and 2, AD-2, which has an alkylamide moiety and an alkyl group on the N of the amide group, and AD-3, which has an alkylamide moiety and an ethylene glycol chain, when used as an alignment agent, can impart good liquid crystal alignment properties and high rubbing resistance, and can also form an alignment agent with excellent low-temperature storage stability. [Industrial Applicability]

[0166] The liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention can be suitably used in various liquid crystal display elements, such as liquid crystal display elements of the IPS driving mode and FFS driving mode. These display elements are not limited to liquid crystal displays for display purposes, and are also useful in light control windows and optical shutters that control the transmission and blocking of light.

Claims

1. A liquid crystal aligning agent comprising the following components (A) and (B): Component (A): Polymer (A) capable of aligning liquid crystal Component (B): a hydroxyalkylamide compound (B) represented by the following formula (1): 【Chemistry 1】 (R is an alkyl group having 1 to 6 carbon atoms, R １ , R ２ each independently represents a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms, and A represents a divalent organic group having 1 to 30 carbon atoms.

2. In the formula (1), R ２ The liquid crystal aligning agent according to claim 1 , wherein is a hydrogen atom.

3. The liquid crystal aligning agent according to any one of claims 1 to 2, wherein in the formula (1), A is a divalent hydrocarbon group having 1 to 30 carbon atoms.

4. The liquid crystal aligning agent according to any one of claims 1 to 3, wherein the hydroxyalkylamide compound (B) is any one of the compounds represented by the following formulas (b-1) to (b-3): 【Chemistry 2】

5. A liquid crystal aligning agent comprising the following components (A') and (B'): Component (A'): Polymer (A') capable of aligning liquid crystal Component (B'): a hydroxyalkylamide compound (B') represented by the following formula (1'): 【Chemistry 3】 (R' is a group "*-C(R ２’ ) ２ -C(R １’ ) ２ -OH" (* represents a bond. R １’ , R ２’ Each independently represents a hydrogen atom or a monovalent organic group having 1 to 6 carbon atoms. R' may be the same or different. n is an integer of 1 to 30. L １’ is a divalent organic group having 1 to 10 carbon atoms, １’ may be the same or different.)

6. The liquid crystal aligning agent according to claim 5, wherein the hydroxyalkylamide compound (B') is any one of compounds represented by the following formulas (b'-1) to (b'-5): 【Chemistry 4】

7. The polymer (A) or the polymer (A') is at least one polymer selected from the group consisting of polyimide precursors and polyimides which are imidized products of the polyimide precursors. The liquid crystal alignment agent according to any one of claims 1 to 6.

8. The liquid crystal aligning agent according to claim 7, wherein the polyimide precursor is obtained by using a tetracarboxylic acid component containing a tetracarboxylic dianhydride represented by the following formula (2): 【Chemistry 5】 (X represents a structure selected from the following formulas (x-1) to (x-13).) 【Chemistry 6】 (R １ ~R ４ R each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group. ５ and R ６ Each of j and k is independently a hydrogen atom or a methyl group. １ and A ２ each independently represents a single bond, -O-, -CO-, -COO-, a phenylene group, a sulfonyl group, or an amide group. ２ may be the same or different. *1 is a bond bonded to one acid anhydride group, and *2 is a bond bonded to the other acid anhydride group.)

9. The liquid crystal aligning agent according to claim 8, wherein the formula (x-1) is selected from the group consisting of the following formulas (x1-1) to (x1-6): 【Chemistry 7】 (*1 is a bond bonded to one acid anhydride group, and *2 is a bond bonded to the other acid anhydride group.)

10. The liquid crystal alignment agent according to any one of claims 7 to 9, wherein the polyimide precursor is obtained using a diamine component containing at least one diamine selected from the diamines represented by the following formulas (3) and (3i): 【Chemistry 8】 (Y ３ represents a divalent organic group represented by the following formula (O), and R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. ３ｉ represents a divalent organic group represented by the following formula (O'): 【Chemistry 9】 (Ar represents a divalent benzene ring, a biphenyl structure, or a naphthalene ring. Two Ar may be the same or different, and any hydrogen atom in the ring may be substituted with a monovalent substituent. p is an integer of 0 or 1. ３ Ha-(CH ２ ) ｎ -(n is an integer of 2 to 18), or the -(CH ２ ) ｎ -of-CH ２ represents a group in which at least a portion of - has been replaced with -O-, -C(=O)-, or -O-C(=O)-. * represents a bond. 【Chemistry 10】 (Ar' represents a divalent benzene ring or a biphenyl structure. Two Ar's may be the same or different, and any hydrogen atom in the ring may be substituted with a monovalent substituent. p' is an integer of 0 or 1. Q ３’ Ha-(CH ２ ) ｎ -(n is an integer of 2 to 18), or the -(CH ２ ) ｎ -of-CH ２ represents a group in which at least a portion of - has been replaced with -O-, -C(=O)-, or -O-C(=O)-. * represents a bond.

11. The liquid crystal aligning agent according to claim 10, wherein the divalent organic group represented by the formula (O) is any one of the following formulas (o-1) to (o-16): 【Chemistry 11】 【Chemistry 12】 【Chemistry 13】 (In the formula, "*" indicates the bond position.)

12. The liquid crystal aligning agent according to any one of claims 7 to 11, wherein the polyimide precursor is obtained using a diamine component containing at least one diamine having a nitrogen-containing structure selected from the group consisting of a nitrogen-containing heterocycle (excluding imide rings of polyimide), a secondary amino group, and a tertiary amino group.

13. A method for producing a liquid crystal alignment film, comprising applying the liquid crystal aligning agent according to any one of claims 1 to 12 to a substrate, baking the applied film, and irradiating the resulting film with polarized radiation.

14. The method for producing a liquid crystal alignment film according to claim 13, wherein the baking is carried out at a temperature of 150 to 250°C.

15. A liquid crystal alignment film formed from the liquid crystal aligning agent according to any one of claims 1 to 12.

16. A liquid crystal display device comprising the liquid crystal alignment film according to claim 15.

17. 17. The liquid crystal display element according to claim 16, which is of an IPS drive type or an FFS drive type.

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