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

Abstract

The present invention provides a liquid crystal alignment agent which is suitable for a liquid crystal alignment film having high film strength and a liquid crystal display element in which AC image sticking is suppressed, and in which solid components do not precipitate during storage at low temperatures. The present invention also provides a liquid crystal alignment film obtained from the liquid crystal alignment agent, and a liquid crystal display element having the liquid crystal alignment film. The liquid crystal alignment agent of the present invention contains the following (A) component and (B) component. (A) component: a polymer (A) having the ability to align liquid crystals. (B) component: a hydroxyalkylamide compound (B) represented by the following formula (1). (R represents 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.)

Description

Technical Field

[0001] This invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element. Background Technology

[0002] Liquid crystal displays (LCDs) have historically been widely used as display units in personal computers, smartphones, mobile phones, television receivers, and the like. An LCD typically includes: a liquid crystal layer sandwiched between a component substrate and a color filter substrate; pixel electrodes and a common electrode that apply an electric field to the liquid crystal layer; an alignment film that controls the orientation of the liquid crystal molecules in the liquid crystal layer; and thin-film transistors (TFTs) that convert electrical signals supplied to the pixel electrodes. Known driving methods for liquid crystal molecules include: vertical electric field methods such as TN (Twisted Nematic) and VA (Vertical Alignment); and lateral electric field methods such as IPS (In-Plane Switching) and FFS (Fringe Field Switching).

[0003] Currently, the most widely used liquid crystal alignment films in industry are manufactured through a so-called rubbing process, which involves unidirectionally rubbing the surface of a film formed on an electrode substrate using a cloth such as cotton, nylon, or polyester. This film is composed of polymers such as polyamic acid and / or polyimides formed by imidizing the polyamic acid. Rubbing is a simple and highly productive industrially useful method. However, with the increasing performance, precision, and size of liquid crystal display elements, various problems have arisen, including damage to the surface of the alignment film generated during rubbing, dust generation, the effects of mechanical force and static electricity, and inhomogeneities within the alignment surface. As an alternative to rubbing, photoalignment methods are known, which impart alignment capabilities to liquid crystals by irradiating them with polarized radiation. Regarding photoalignment methods, methods utilizing photoisomerization reactions, photocrosslinking reactions, and photodecomposition reactions have been proposed (see, for example, Non-Patent Literature 1 and Patent Literature 1).

[0004] In recent years, large-screen, high-resolution LCD TVs have become mainstream. Furthermore, the widespread adoption of smaller display terminals such as smartphones, tablet PCs, and car navigation systems has further increased the demands on the high quality of LCD components. For reliability testing of LCD components used in mobile applications like smartphones and in-vehicle applications like car navigation systems, panel vibration tests are sometimes conducted. These vibration tests require that no defects such as bright spots occur. To obtain LCD components that do not produce defects after vibration testing, methods to improve the mechanical strength of the liquid crystal alignment film can be considered, for example. One method to improve the mechanical strength, particularly the film strength, of the liquid crystal alignment film is to add a crosslinking agent to the liquid crystal alignment agent.

[0005] Furthermore, in IPS and FFS driving methods, the stability of liquid crystal alignment becomes crucial. If the alignment stability is low, the liquid crystal will not return to its initial state after prolonged driving, leading to reduced contrast and screen burn-in (hereinafter referred to as AC image retention).

[0006] As a means of solving these problems, liquid crystal alignment agents containing specific polyimide components and specific hydroxyalkylamide compounds have been proposed (for example, see Patent Document 2).

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 9-297313

[0010] Patent Document 2: WO2018 / 092811 Publication

[0011] Non-patent literature

[0012] Non-Patent Literature 1: "Liquid Crystal Optical Alignment Film" by Kido Waki ​​and Ichimura, Functional Materials, November 1997, Vol. 17, No. 11, pp. 13-22 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] Liquid crystal alignment agents are typically stored at extremely low temperatures (e.g., -20°C) from manufacturing to market to prevent polymer degradation.

[0015] On the other hand, in the research of the inventors, it was found that when the hydroxyalkylamide compound described in Patent Document 2 was added to the liquid crystal alignment agent, although the film strength of the obtained liquid crystal alignment film was improved and a liquid crystal display element with suppressed AC image retention was obtained, the solid components contained in the liquid crystal alignment agent would precipitate out when stored at low temperature.

[0016] If the precipitated solid components are difficult to dissolve again, they may cause defects such as printing problems in the manufacturing process of liquid crystal display elements. The cause of such solid component precipitation is undetermined, but one speculated reason is the high polarity of the hydroxyalkylamide compound used in the liquid crystal alignment agent. Therefore, liquid crystal alignment agents that do not precipitate solid components during frozen storage are required.

[0017] In summary, the object of this invention is to provide a liquid crystal alignment agent suitable for use in liquid crystal alignment films with high film strength and liquid crystal display elements with suppressed AC image retention, without solid component precipitation during low-temperature storage. A further object of this invention is to provide a liquid crystal alignment film obtained from this liquid crystal alignment agent and a liquid crystal display element having this liquid crystal alignment film.

[0018] Solution for solving the problem

[0019] In order to solve the above problems, the inventors conducted in-depth research and found that liquid crystal alignment agents containing specific hydroxyalkylamide compounds are extremely effective in achieving the above objectives, thus completing the present invention.

[0020] The present invention includes the following solutions.

[0021] [1] A liquid crystal alignment agent containing the following components (A) and (B).

[0022] (A) Component: Polymer (A) with the ability to orient liquid crystals.

[0023] (B) Component: Hydroxyalkylamide compound (B) as shown in formula (1) below.

[0024]

[0025] (R represents an alkyl group with 1 to 6 carbon atoms, R1 and R2 independently represent a hydrogen atom or a monovalent organic group with 1 to 6 carbon atoms, and A represents a divalent organic group with 1 to 30 carbon atoms.)

[0026] Another aspect of the present invention includes the following.

[0027] [1] A liquid crystal alignment agent containing the following components (A') and (B').

[0028] (A') Component: A polymer (A') with the ability to orient liquid crystals.

[0029] (B') Component: Hydroxyalkylamide compound (B') as shown in formula (1') below.

[0030]

[0031] (R' represents the group "*-C(R)" 2’ )2-C(R 1’ )2-OH" (* indicates a bonded bond. R 1’ R 2’ Each R' represents a monovalent organic group (each independently representing a hydrogen atom or a carbon atom number 1 to 6), and the multiple R's may optionally be the same or different. n is an integer from 1 to 30. L 1’ It is a divalent organic group with 1 to 10 carbon atoms, and multiple L 1’ (Optional: either the same or different.)

[0032] Invention Effects

[0033] According to the present invention, a liquid crystal alignment agent, a liquid crystal alignment film obtained from the liquid crystal alignment agent, and a liquid crystal display element having the liquid crystal alignment film are provided. The liquid crystal alignment agent is suitable for use in liquid crystal alignment films with high film strength and liquid crystal display elements in which AC image retention is suppressed, and the solid components do not precipitate when stored at low temperatures. Detailed Implementation

[0034] 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 description of the constituent elements described below is only an example of one embodiment of the present invention and is not intended to be specific to these contents.

[0035] In the following description, "(methyl)propene" refers to both propylene and methylpropene. Furthermore, examples of "halogen atoms" include: fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc.

[0036] (Liquid crystal alignment agent)

[0037] The liquid crystal alignment agent of the present invention contains a polymer (A) (also referred to as component (A) in this invention) or a polymer (A') (also referred to as component (A') in this invention) that has the ability to align liquid crystals. Polymer (A') includes preferred specific examples, and compounds identical to polymer (A) can be listed.

[0038] Furthermore, one embodiment of the liquid crystal alignment agent of the present invention contains the above-described polymer (A) and the hydroxyalkylamide compound (B) shown in the above formula (1) (also referred to as component (B) in the present invention).

[0039] Furthermore, another embodiment of the liquid crystal alignment agent of the present invention contains the above-mentioned polymer (A') and the hydroxyalkylamide compound (B') shown in the above formula (1') (also referred to as component (B') in the present invention).

[0040] <(A) component, (A') component>

[0041] The liquid crystal alignment agent of the present invention contains, like known liquid crystal alignment agents, a polymer capable of aligning liquid crystals, and there is no particular limitation on the polymer as long as it has the ability to align liquid crystals.

[0042] Examples of such polymers include: polyimide precursors, polyimides that are imide derivatives of polyimide precursors, acrylic polymers, methacrylic polymers, acrylamide polymers, methacrylamide polymers, polystyrene, polysiloxanes, polyamides, polyesters, polyurethanes, polycarbonates, polyureas, polyphenols (novolacresin), maleimide polymers, and polymers incorporating compounds having isocyanuric acid backbones or triazine backbones.

[0043] The following substances can be listed as raw materials used to manufacture these polymers.

[0044] When the polymer is a polyimide precursor such as polyamic acid or polyamic acid ester, or a polyimide, at least one compound selected from tetracarboxylic acids or their derivatives (preferably tetracarboxylic dianhydride) and a diamine can be included.

[0045] In the case of a polymer that is a (meth)acrylic acid polymer, examples include (meth)acrylic acid or its derivatives, and (meth)acrylates or their derivatives.

[0046] In the case of a polymer that is a (meth)acrylamide polymer, examples of (meth)acrylamide or its derivatives can be listed.

[0047] When the polymer is polystyrene, styrene or its derivatives can be listed.

[0048] In the case of a polymer that is a polysiloxane, examples of silane compounds having methoxy or ethoxy groups can be listed.

[0049] When the polymer is polyamide, at least one dicarboxylic acid component and a diamine component selected from dicarboxylic acids and their derivatives can be listed.

[0050] When the polymer is a polyester, at least one dicarboxylic acid component and a diol component selected from dicarboxylic acids and their derivatives can be listed.

[0051] In the case of polyurethane polymers, isocyanate compounds and compounds containing hydroxyl groups can be listed.

[0052] In the case of a polymer that is polycarbonate, examples include bisphenol derivatives and phosgene or phosgene equivalents (e.g., trichlorophosgene) or diphenyl carbonate.

[0053] In the case of a polymer that is polyurea, diisocyanate derivatives and diamine components can be listed.

[0054] In the case where the polymer is a maleimide polymer, examples include maleimide derivative homopolymers or copolymers with styrene.

[0055] In the case where the polymer is a polymer incorporating compounds having an isocyanuric acid skeleton or a triazine skeleton, examples of compounds having an isocyanuric acid skeleton or a triazine skeleton can be listed.

[0056] <<Polyimide Polymers>>

[0057] The polymer contained in the liquid crystal alignment agent of the present invention is preferably selected from one or more polymers (hereinafter also referred to as polyimide-based polymers) from the group consisting of polyimide precursors and polyimides that are imide derivatives of polyimide precursors, from the viewpoints of practicality as liquid crystal alignment agents, mechanical strength of coating films and liquid crystal alignment properties.

[0058] The aforementioned polyimide polymers can be manufactured using known methods. For example, polyamic acid, as a polyimide precursor, is obtained by polymerizing (condensing) a tetracarboxylic acid component composed of a tetracarboxylic dianhydride or its derivative with a diamine component, and then imidizing this polyimide precursor to obtain the polyimide. Examples of tetracarboxylic dianhydride derivatives include tetracarboxylic acid dihalides, tetracarboxylic acid dialkyl esters, or tetracarboxylic acid dialkyl ester dihalides.

[0059] <<<Tetracarboxylic acid components>>>

[0060] Polyamic acids, as precursors to polyimides, can be exemplified by substances derived from tetracarboxylic acid components, including aromatic, acyclic aliphatic, or alicyclic tetracarboxylic dianhydrides. Here, aromatic tetracarboxylic dianhydrides are dianhydrides obtained by intramolecular dehydration of four carboxyl groups, including at least one carboxyl group bonded to an aromatic ring. Acyclic aliphatic tetracarboxylic dianhydrides are dianhydrides obtained by intramolecular dehydration of four carboxyl groups bonded to a chain hydrocarbon structure. It is not necessary for the structure to consist solely of a chain hydrocarbon structure; a portion of the structure may also have an alicyclic or aromatic ring structure.

[0061] Furthermore, the alicyclic tetracarboxylic dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxyl groups, each containing at least one carboxyl group bonded to the alicyclic structure. None of these four carboxyl groups are bonded to an aromatic ring.

[0062] Furthermore, it does not need to consist solely of an alicyclic structure; it can also have a chain hydrocarbon structure or an aromatic ring structure in a portion of it.

[0063] In the case of the polyamic acid of the present invention, it is preferable to obtain a substance from a tetracarboxylic acid component comprising a tetracarboxylic acid dianhydride as shown in formula (2) below.

[0064]

[0065] (X represents a structure selected from the following formulas (x-1)~(x-13).)

[0066]

[0067] (R 1 ~R 4 Each of the following can be independently represented: a hydrogen atom, a halogen atom, an alkyl group with 1 to 6 carbon atoms, an alkenyl group with 2 to 6 carbon atoms, an alkynyl group with 2 to 6 carbon atoms, a monovalent organic group containing a fluorine atom with 1 to 6 carbon atoms, or a phenyl group. 5 and R 6 Each A1 and A2 independently represents a hydrogen atom or a methyl group. j and k are integers 0 or 1. A1 and A2 independently represent a single bond, -O-, -CO-, -COO-, phenylene, sulfonyl, or amide group, respectively. Multiple A2 groups may optionally be the same or different. *1 represents a bond bonded to an anhydride group on one side, and *2 represents a bond bonded to an anhydride group on the other side.

[0068] As a preferred specific example of the tetracarboxylic acid dianhydride or its derivatives shown in formula (2) above, X can be selected from substances in formulas (x-1) to (x-8) and (x-10) to (x-13) above.

[0069] Regarding the above formula (x-1), the structure is preferably selected from the group consisting of the following formulas (x1-1) to (x1-6).

[0070]

[0071] (*1 represents a bond bonded to an anhydride group on one side, and *2 represents a bond bonded to an anhydride group on the other side.)

[0072] As preferred examples of the above formulas (x-12) and (x-13), the following formulas (x-14) to (x-29) can be listed. It should be noted that the "*" in the formulas indicates the bonding position.

[0073]

[0074] The amount of tetracarboxylic acid dianhydride or its derivative shown in formula (2) above preferably comprises 60 to 100 mol% of 1 mole of the total tetracarboxylic acid component that reacts with the diamine component, more preferably 80 to 100 mol%, and even more preferably 90 to 100 mol%.

[0075] <<<Diamine Component>>>

[0076] The diamine component used to manufacture the polyimide precursor is not particularly limited, but it is preferred to include a diamine component containing at least one diamine selected from the diamines shown in formulas (3) and (3i).

[0077]

[0078] (Y3 represents the divalent organic group shown in the following formula (O). R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Y) 3i (This represents the divalent organic group shown in the following formula (O').

[0079]

[0080] (Ar represents a divalent benzene ring, biphenyl structure, or naphthalene ring. The two Ars may be the same or different, and any hydrogen atom of the above ring may be substituted with a monovalent substituent. p is an integer 0 or 1. Q3 represents -(CH2) n - (n is an integer from 2 to 18), or the above - (CH2). n A group formed by replacing at least a portion of -CH2- with any one of -O-, -C(=O)-, or -O-C(=O)-. * indicates a bond.

[0081]

[0082] (Ar' represents a divalent benzene ring or biphenyl structure. The two Ar's may be the same or different, and any hydrogen atom of the ring may be substituted with a monovalent substituent. p' is an integer 0 or 1. Q) 3’ It represents -(CH2) n - (n is an integer from 2 to 18), or the above - (CH2). n A group formed by replacing at least a portion of -CH2- with any one of -O-, -C(=O)-, or -O-C(=O)-. * indicates a bond.

[0083] Examples of substituents for the aforementioned rings include: halogen atoms, alkyl groups with 1 to 10 carbon atoms, alkenyl groups with 2 to 10 carbon atoms, alkoxy groups with 1 to 10 carbon atoms, fluoroalkyl groups with 1 to 10 carbon atoms, fluoroalkenyl groups with 2 to 10 carbon atoms, fluoroalkoxy groups with 1 to 10 carbon atoms, carboxyl groups, hydroxyl groups, alkyloxycarbonyl groups with 1 to 10 carbon atoms, cyano groups, nitro groups, etc.

[0084] From the viewpoint of improving liquid crystal orientation, the divalent organic group shown in the above formula (O) is preferably the divalent organic group shown in the following formulas (o-1) to (o-16).

[0085]

[0086] (The asterisk (*) in the formula indicates the bonding location.)

[0087] From the viewpoint of improving liquid crystal orientation, the divalent organic group shown in the above formula (O') is preferably the divalent organic group shown in the above formulas (o-7) to (o-16).

[0088] As preferred specific examples of the diamine shown in the above formula (3i), compounds shown in the following formulas (3i-1) to (3i-5) can be listed.

[0089]

[0090] The total ratio of the diamine shown in formula (3) and the diamine shown in formula (3i) relative to 1 mole of the diamine component is preferably 1 to 95 mol%, more preferably 1 to 90 mol%, and even more preferably 5 to 90 mol%.

[0091] From the viewpoint of improving the voltage retention rate of the obtained liquid crystal alignment film, the polyimide polymer used in this invention may also have at least one nitrogen-containing structure (hereinafter also referred to as a nitrogen-containing structure) selected from the group consisting of nitrogen-containing heterocycles (wherein excluding the imide ring possessed by the polyimide), secondary amino groups, and tertiary amino groups. A 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, in at least a portion of the raw material.

[0092] Examples of nitrogen-containing heterocycles that can be present in diamines with nitrogen-containing structures include: pyrrole, imidazole, pyrazole, triazole, pyridine, pyrimidine, pyridazine, pyrazine, indole, benzimidazole, purine, quinoline, isoquinoline, naphthidine, quinoxaline, phthalazine, triazine, carbazole, acridine, piperidine, piperazine, pyrrolidine, and hexamethyleneimine. Pyridine, pyrimidine, pyrazine, piperidine, piperazine, quinoline, carbazole, or acridine are preferred.

[0093] The diamines with nitrogen-containing structures mentioned above may have secondary and tertiary amino groups, for example, represented by the following formula (n).

[0094]

[0095] In the above formula (n), R represents a hydrogen atom or a monovalent hydrocarbon group with 1 to 10 carbon atoms. "*" represents a bond bonded to the hydrocarbon group.

[0096] As a monovalent hydrocarbon group of R in the above formula (n), examples include: alkyl groups such as methyl, ethyl, and propyl; cycloalkyl groups such as cyclohexyl; and aryl groups such as phenyl and methylphenyl. R is preferably a hydrogen atom or a methyl group.

[0097] 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 formulas (Dp-1) to (Dp-9) below, and compounds represented by formulas (z-1) to (z-18) below.

[0098]

[0099]

[0100] From the viewpoint of improving the voltage retention rate of liquid crystal display elements, the proportion of diamine having a nitrogen-containing structure used relative to the total amount of diamine used in synthesis is preferably 1 mol% or more, more preferably 2 mol% or more. Furthermore, this proportion is preferably 90 mol% or less, more preferably 80 mol% or less.

[0101] The polyimide polymers used in this invention may also contain diamines other than those described above. Examples of other diamines are listed below, but the invention is not limited thereto.

[0102] Examples include: diamines with 6 to 30 carbon atoms having the group "-N(D)-" (D represents a carbamate protecting group) within the molecule; 4,4'-diaminoazobenzene; and the following formula (d T -1)~(d T-3) Diamines such as the diamines shown have photo-oriented groups; 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-aminobenzyl)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 containing carboxyl groups, such as diamine compounds of formulas (3b-1) to (3b-4); 4-(2-(methylamino)ethyl)aniline, 4-(2-aminoethyl)aniline, 4,4'-diaminodiphenylmethane, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenyl ether, 4,4'-diaminobenzoyl aniline, 4,4'-diaminoazobenzene, 1-(4-aminophenyl)-1,3,3-trimethyl-1H-indane-5- Amines, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indene-6-amine; diamines having urea bonds, such as the diamines shown in formulas (h-1) to (h-3) below; diamines having amide bonds, such as the diamines shown in formulas (h-4) to (h-6) below; diamines having photopolymerizable groups at the ends, such as 2-(2,4-diaminophenoxy)ethyl methacrylate and 2,4-diamino-N,N-diallylaniline; cholesteryloxy-3,5-diaminobenzene, cholesteryloxy-3,5-diaminobenzene, cholesteryloxy-2,4-diaminobenzene, and cholesteryl 3,5-diaminobenzoic acid. Diamines having a steroidal skeleton, such as alkyl esters, cholesteryl 3,5-diaminobenzoate, lanostane 3,5-diaminobenzoate, and 3,6-bis(4-aminobenzoyloxy)cholestane; diamines represented by formulas (V-1) to (V-6) below; diamines having siloxane bonds, such as 1,3-bis(3-aminopropyl)-tetramethyldisiloxane; diamines having an oxazoline structure, such as formulas (Ox-1) to (Ox-2) below; and diamines formed by bonding two amino groups to groups represented by any of the formulas (Y-1) to (Y-167) as described in International Publication No. 2018 / 117239.

[0103]

[0104]

[0105] (In equation (3b-1), A) 1The following symbols represent single bonds: -CH2-, -C2H4-, -C(CH3)2-, -CF2-, -C(CF3)2-, -O-, -CO-, -NH-, -N(CH3)-, -CONH-, -NHCO-, -CH2O-, -OCH2-, -COO-, -OCO-, -CON(CH3)-, or -N(CH3)CO-. m1 and m2 independently represent integers 0 to 4, and m1 + m2 represents integers 1 to 4. In equation (3b-2), m3 and m4 independently represent integers 1 to 5. In equation (3b-3), A... 2 m5 represents a straight-chain or branched alkyl group with 1 to 5 carbon atoms, where m5 represents an integer from 1 to 5. In formula (3b-4), A 3 and A 4 Each of these can independently represent a single bond, -CH2-, -C2H4-, -C(CH3)2-, -CF2-, -C(CF3)2-, -O-, -CO-, -NH-, -N(CH3)-, -CONH-, -NHCO-, -CH2O-, -OCH2-, -COO-, -OCO-, -CON(CH3)-, or -N(CH3)CO-, where m6 represents an integer from 1 to 4.

[0106]

[0107]

[0108] (X v1 ~X v4 X p1 ~X p2 Each can be represented independently as -(CH2) a - (a is an integer from 1 to 15), -CONH-, -NHCO-, -CON(CH3)-, -NH-, -O-, -CH2O-, -CH2OCO-, -COO-, or -OCO-, X v5 This represents -O-, -CH2O-, -CH2OCO-, -COO-, or -OCO-. X a This indicates a single bond, -O-, -NH-, or -O-(CH2). m -O- (m represents an integer from 1 to 6), R v1 ~R v4 R 1a ~R 1b Each of these can be independently represented as 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.

[0109]

[0110] As diamines with 6 to 30 carbon atoms having the intramolecular group "-N(D)- (D represents a carbamate protecting group)," the compounds shown in formulas (5-1) to (5-10) below can be listed.

[0111]

[0112] (Boc represents tert-butyloxycarbonyl.)

[0113] <(B) Component>

[0114] One embodiment of the liquid crystal alignment agent of the present invention is characterized by containing a hydroxyalkylamide compound (B) as shown in formula (1).

[0115]

[0116] (R represents an alkyl group with 1 to 6 carbon atoms, R1 and R2 independently represent a hydrogen atom or a monovalent organic group with 1 to 6 carbon atoms, and A represents a divalent organic group with 1 to 30 carbon atoms.)

[0117] Examples of alkyl groups with 1 to 6 carbon atoms in R in formula (1) above include: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, cyclopentyl, and cyclohexyl.

[0118] Examples of monovalent organic groups with 1 to 6 carbon atoms in R1 and R2 in formula (1) above include: alkyl groups with 1 to 6 carbon atoms, alkenyl groups with 2 to 6 carbon atoms, alkynyl groups with 2 to 6 carbon atoms, or heteroatom-containing groups whose carbon-carbon inter-carbon contains heteroatoms, and groups formed by substituting some or all of the hydrogen atoms of the above alkyl, alkenyl, alkynyl and heteroatom-containing groups with substituents.

[0119] Examples of heteroatom-containing groups include those having at least one selected from the group consisting of oxygen, nitrogen, silicon, phosphorus, and sulfur atoms, such as -O-, -NR- (where R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms), -CO-, -S-, -CO-, and groups formed by combining these. Among these, -O- is preferred.

[0120] Examples of substituents mentioned above include: halogen atoms such as fluorine, chlorine, bromine, and iodine; alkoxy groups such as methoxy, ethoxy, and propoxy; alkoxycarbonyl groups such as methoxycarbonyl and ethoxycarbonyl; alkoxycarbonyloxy groups such as methoxycarbonyloxy and ethoxycarbonyloxy; and cyano, nitro, and hydroxyl groups.

[0121] From the viewpoint of improving liquid crystal orientation, R1 in the above formula (1) is preferably a hydrogen atom or a methyl group, and R2 is preferably a hydrogen atom.

[0122] Examples of divalent organic groups with 1 to 30 carbon atoms in A of formula (1) above include: divalent hydrocarbon groups, divalent heteroatom-containing groups in which the carbon-carbon space of the hydrocarbon group contains a group having the above-mentioned heteroatom, and divalent organic groups formed by replacing some or all of the hydrogen atoms of the above-mentioned divalent hydrocarbon groups and divalent heteroatom-containing groups with substituents exemplified in R1 and R2 above.

[0123] Examples of divalent hydrocarbon groups include those formed by removing two hydrogen atoms from the following hydrocarbons: alkanes such as methane, ethane, propane, and butane; alkenes such as ethylene, propylene, butene, and pentene; alkynes such as acetylene, propyne, butyne, and pentyne, which are chain hydrocarbons with 1 to 30 carbon atoms; cycloalkanes such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, norbornane, and adamantane; alicyclic hydrocarbons such as cyclopropylene, cyclobutene, cyclopentene, cyclohexene, and norbornene, which are cycloalkenes with 3 to 30 carbon atoms; and aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, naphthalene, methylnaphthalene, dimethylnaphthalene, and anthracene, which are aromatic hydrocarbons with 6 to 30 carbon atoms.

[0124] As A in the above formula (1), it is preferably a divalent hydrocarbon group with 1 to 30 carbon atoms, and more preferably a divalent hydrocarbon group obtained by removing two hydrogen atoms from a divalent chain hydrocarbon with 1 to 30 carbon atoms or an aromatic hydrocarbon with 6 to 30 carbon atoms.

[0125] Preferably, the divalent chain hydrocarbons with 1 to 30 carbon atoms are divalent chain hydrocarbons with 2 to 30 carbon atoms, and more preferably divalent chain hydrocarbons with 2 to 16 carbon atoms.

[0126] The hydroxyalkylamide compound represented by formula (1) above is preferably any compound among the compounds represented by formulas (b-1) to (b-3) below.

[0127]

[0128] The preferred content of the hydroxyalkylamide compound represented by the above formula (1) in the liquid crystal alignment agent of the present invention is preferably 0.1 to 50 parts by mass relative to 100 parts by mass of component (A), more preferably 0.1 to 30 parts by mass.

[0129] <(B') component>

[0130] Another embodiment of the liquid crystal alignment agent of the present invention is characterized by containing a hydroxyalkylamide compound (B') represented by the following formula (1').

[0131]

[0132] (R' represents the group "*-C(R)" 2’ )2-C(R 1’ )2-OH" (* indicates a bonded bond. R 1’ R 2’ Each R' represents a monovalent organic group (each independently representing a hydrogen atom or a carbon atom number 1 to 6), and the multiple R's may optionally be the same or different. n is an integer from 1 to 30. L 1’ It is a divalent organic group with 1 to 10 carbon atoms, and multiple L 1’ (Optional: either the same or different.)

[0133] R in the above equation (1') 1’ and R 2’ The monovalent organic groups with 1 to 6 carbon atoms can be listed as structures exemplified in R1 and R2 in the above formula (1), including preferred specific examples, and are the same as R1 and R2 respectively.

[0134] As L in the above equation (1') 1’ Divalent organic groups having 1 to 10 carbon atoms include, for example, divalent hydrocarbon groups having 1 to 10 carbon atoms, divalent heteroatom-containing groups having a heteroatom between carbon atoms of the hydrocarbon group, and divalent organic groups formed by replacing some or all of the hydrogen atoms of the above-mentioned divalent hydrocarbon groups and divalent heteroatom-containing groups with substituents exemplified in R1 and R2 in the above formula (1). As a specific example of a divalent hydrocarbon group, the hydrocarbon group exemplified in A in the above formula (1) can be listed.

[0135] Preferably, L in the above formula (1') is... 1’ Preferably, it is a divalent hydrocarbon group with 1 to 10 carbon atoms, and more preferably, it is a divalent hydrocarbon group obtained by removing two hydrogen atoms from a divalent chain hydrocarbon with 1 to 10 carbon atoms or an aromatic hydrocarbon with 6 to 10 carbon atoms.

[0136] Preferably, the divalent chain hydrocarbons having 1 to 10 carbon atoms are divalent chain hydrocarbons having 2 to 10 carbon atoms, and more preferably divalent chain hydrocarbons having 2 to 8 carbon atoms.

[0137] In the above formula (1'), n is more preferably an integer from 1 to 20, and even more preferably an integer from 2 to 20.

[0138] The hydroxyalkylamide compound represented by formula (1') above is preferably any compound among the compounds represented by formulas (b'-1) to (b'-5) below.

[0139]

[0140] The preferred content of the hydroxyalkylamide compound represented by the above formula (1') in the liquid crystal alignment agent of the present invention is 0.1 to 50 parts by mass relative to 100 parts by mass of component (A'), more preferably 0.1 to 30 parts by mass.

[0141] <Manufacturing Method of Polyamic Acid>

[0142] Polyamic acid, the polyimide precursor used in this invention, can be manufactured by the following method. Specifically, it can be synthesized by reacting the above-mentioned tetracarboxylic acid component with the above-mentioned diamine component in the presence of an organic solvent at -20 to 150°C, preferably at 0 to 50°C, for 30 minutes to 24 hours, preferably 1 to 12 hours (condensation reaction).

[0143] Specific examples of organic solvents used in the above reactions include: N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and 1,3-dimethyl-2-imidazolinone. Furthermore, where the polymer has high solvent solubility, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or solvents shown in formulas [D-1] to [D-3] below can be used. Two or more of these can also be used in combination.

[0144]

[0145] (In formula [D-1], D) 1 In formula [D-2], D represents an alkyl group with 1 to 3 carbon atoms. 2 In formula [D-3], D represents an alkyl group having 1 to 3 carbon atoms. 3 (Refers to alkyl groups with 1 to 4 carbon atoms).

[0146] The reaction can be carried out at any concentration, preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The reaction is initially carried out at a high concentration, and then a solvent may be added. In the reaction, the ratio of the total molar number of the diamine component to the total molar number of the tetracarboxylic acid component is preferably 0.8 to 1.2. Similar to conventional polycondensation reactions, the closer this molar ratio is to 1.0, the larger the molecular weight of the resulting polyamic acid.

[0147] The polyamic acid obtained in the above reaction can be precipitated and recovered by injecting the reaction solution into a poor solvent while stirring it thoroughly. Alternatively, after several precipitation processes, washing with the poor solvent, and drying at room temperature or by heating, purified polyamic acid powder can be obtained. Poor solvents are not particularly limited, but examples include: water, methanol, ethanol, hexane, butyl cellosolve, acetone, and toluene.

[0148] When the polyimide precursor is a polyamic acid ester, it can be manufactured by the following known methods: (1) a method of esterifying a polyamic acid ester obtained from a tetracarboxylic acid dianhydride and a diamine. (2) a method based on the reaction of a tetracarboxylic acid diester dichloride with a diamine. (3) a method of polycondensing a tetracarboxylic acid diester with a diamine, etc.

[0149] The aforementioned polyimide precursor can also be an end-modified polymer obtained by using a suitable end-capping agent together with the tetracarboxylic acid derivative and diamine as described above during the manufacture of the polyimide precursor.

[0150] Examples of end-modifying agents include: acetic anhydride, maleic anhydride, nadic anhydride, phthalic anhydride, itaconic anhydride, cyclohexanedicarboxylic anhydride, 3-hydroxyphthalic anhydride, trimellitic anhydride, and other acid anhydrides; di-tert-butyl dicarbonate; aniline, 2-aminophenol, 3-aminophenol, 4-aminosalicylic acid, 5-aminosalicylic acid, 6-aminosalicylic acid, 2-aminobenzoic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, and other monoamine compounds; ethyl isocyanate, phenyl isocyanate, naphthyl isocyanate, and other monoisocyanate compounds.

[0151] The proportion of the terminal modifier used relative to 100 moles of the total diamine component used is preferably 40 moles or less, more preferably 30 moles or less.

[0152] <Manufacturing Method of Polyimide>

[0153] The polyimide used in this invention can be manufactured by imidizing polyamic acid or polyamic acid ester as a polyimide precursor using known methods.

[0154] In polyimides, the ring-closing rate (also known as the imidization rate) of the functional groups in polyamic acid or polyamic ester is not necessarily 100% and can be adjusted arbitrarily according to the application and purpose.

[0155] Methods for obtaining polyimide by imidizing the above-mentioned polyamic acid or polyamic acid ester include: thermal imidization by directly heating a solution of the above-mentioned polyamic acid or polyamic acid ester, or catalytic imidization by adding a catalyst to a solution of the above-mentioned polyamic acid or polyamic acid ester. The temperature during thermal imidization is 100–400°C, preferably 120–250°C, and preferably carried out while removing water generated by the imidization reaction from the system.

[0156] 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 basic catalyst is 0.5 to 30 molar times, preferably 2 to 20 molar times, of the ammonium acid group or ammonium ester group, and the amount of acid anhydride is 1 to 50 molar times, preferably 3 to 30 molar times, of the ammonium acid group or ammonium ester group. Examples of basic catalysts include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine, among which pyridine is preferred due to its moderate basicity for the reaction to proceed. Examples of acid anhydrides include acetic anhydride, trimellitic anhydride, and phenylmethyltetrahydroquinone, among which acetic anhydride is preferred because it facilitates purification after the reaction. The imidization rate obtained by catalytic imidization can be controlled by adjusting the amount of catalyst, reaction temperature, and reaction time.

[0157] In the case of recovering the generated polyimide from the reaction solution of catalytic imidization, the reaction solution is added to a solvent to precipitate the polymer. Examples of solvents for precipitation include methanol, ethanol, isopropanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, toluene, benzene, and water. The polymer precipitated by adding the polymer to the solvent can be filtered, recovered, and then dried at room temperature or under reduced pressure. Furthermore, repeating the reprecipitation recovery operation 2 to 10 times by dissolving the recovered polymer in a solvent again reduces impurities in the polymer. Examples of solvents used in this process include alcohols, ketones, and hydrocarbons. Using three or more solvents selected from these sources further improves the purification efficiency and is therefore preferred.

[0158] <Polymer solution viscosity / molecular weight>

[0159] Regarding the polyamic acid, polyamic acid ester, and polyimide used in this invention, from a workability point of view, it is preferable that when they are prepared into solutions with a concentration of 10-15% by mass, for example, a solution viscosity of 10-1000 mPa·s, but there is no particular limitation. It should be noted that the solution viscosity (mPa·s) of the above polymers is the value measured at 25°C using an E-type rotational viscometer for a polymer solution with a concentration of 10-15% by mass prepared using a good solvent (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

[0160] The weight-average molecular weight (Mw) of the polyamic acid, polyamic acid ester, and polyimide, as determined by gel permeation chromatography (GPC), converted from polystyrene, is preferably 1,000 to 500,000, more preferably 2,000 to 500,000. Furthermore, the molecular weight distribution (Mw / Mn) shown by the ratio of Mw to the number-average molecular weight (Mn) of polystyrene determined by GPC is preferably 15 or less, more preferably 10 or less. This molecular weight range ensures good liquid crystal alignment of the liquid crystal display element.

[0161] <Preferred Options for Liquid Crystal Alignment Agents>

[0162] As a preferred embodiment of the liquid crystal alignment agent of the present invention, for example, the following method can be listed: adding the hydroxyalkylamide compound of the above formula (1) or (1') to a solution formed by dissolving a polymer having the ability to align liquid crystals in a solvent.

[0163] The content (concentration) of the polymer contained in the liquid crystal alignment agent of the present invention can also be appropriately changed according to the setting of the thickness of the coating to be formed. From the viewpoint of forming a uniform and defect-free coating, it is preferably 1% by mass or more, and from the viewpoint of the storage stability of the solution, it is preferably 10% by mass or less.

[0164] The content of the hydroxyalkylamide compound of formula (1) or (1') above is preferably 1 to 15% by mass, more preferably 2 to 10% by mass, and particularly preferably 2 to 8% by mass, relative to the total content of the polymer contained in the liquid crystal alignment agent and the hydroxyalkylamide compound of formula (1) or (1') above.

[0165] The solvent used in liquid crystal alignment agents is not particularly limited as long as it uniformly dissolves the polymer components. Specific examples include: N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyllactic acid, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, γ-valerolactone, 1,3-dimethyl-2-imidazolinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide. Amides, 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, N-cyclohexyl-2-pyrrolidone (also collectively referred to as "good solvents"), etc. Among these, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide, or γ-butyrolactone are preferred. The content of the good solvent is preferably 20-99% by mass of the total solvent contained in the liquid crystal alignment agent, more preferably 20-90% by mass, and particularly preferably 30-80% by mass.

[0166] Furthermore, the solvent contained in the liquid crystal alignment agent is preferably a mixed solvent, in addition to the solvents mentioned above, which also includes a solvent (also known as a poor solvent) that improves the coatability and surface smoothness of the coating film when applying the liquid crystal alignment agent. Specific examples of the solvents used are given below, but are not limited thereto.

[0167] For example, the following can be listed: diisopropyl ether, diisobutyl ether, diisobutylmethanol (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 monoisopentyl ether, ethylene glycol monohexyl ether, propylene glycol monobutyl ether, 1-(2-butoxyethoxy)-2-propanediol, etc. Alcohols, 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, diisobutyl ketone (2,6-dimethyl-4-heptanone), etc. The content of the undesirable solvent is preferably 1 to 80% by mass of the total solvent contained in the liquid crystal alignment agent, more preferably 10 to 80% by mass, and particularly preferably 20 to 70% by mass. The type and content of the undesirable solvent are appropriately selected according to the coating apparatus, coating conditions, coating environment, etc. of the liquid crystal alignment agent.

[0168] Among them, diisobutyl methanol, 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 are preferred.

[0169] Preferred combinations of good and bad 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 monobutyl ether. Diethyl ether; N-methyl-2-pyrrolidone, 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 diisobutylmethanol; N-methyl-2-pyrrolidone, γ-butyrolactone and dipropylene glycol dimethyl ether; N-methyl-2-pyrrolidone, propylene glycol monobutyl ether and dipropylene glycol dimethyl ether, etc.

[0170] The liquid crystal alignment agent of the present invention may also contain additional components other than polymer components and solvents (hereinafter also referred to as additive components). Examples of such additive components include: adhesion promoters for improving the adhesion between the liquid crystal alignment film and the substrate, and the adhesion between the liquid crystal alignment film and the sealing material; compounds for improving the strength of the liquid crystal alignment film (hereinafter also referred to as crosslinking compounds); and dielectrics and conductive materials for adjusting the dielectric constant and resistance of the liquid crystal alignment film.

[0171] As the aforementioned crosslinking compounds, from the viewpoint of exhibiting good resistance to AC remnants and high improvement in film strength, compounds selected from the following can be listed: compounds having at least one group selected from the group consisting of ethylene oxide, oxetane, protected isocyanate group, protected isothiocyanate group, a group containing an oxazoline ring structure, a group containing a Michaelis acid structure, and a cyclic carbonate group; hydroxyalkylamide compounds other than those shown in formulas (1) and (1') above; or compounds shown in formula (e) below.

[0172]

[0173] (A represents an (m+n) valence organic group with an aromatic ring. m represents an integer from 1 to 6, and n represents an integer from 0 to 4. R) e R f Each of these groups 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 optionally be substituted with a monovalent group; specific examples of such monovalent groups include the monovalent organic groups represented by the substituents of Ar in formula (O) above (excluding alkoxy groups having 1 to 10 carbon atoms).

[0174] Specific examples of compounds containing ethylene oxide include compounds described in paragraph

[0037] of Japanese Patent Application Publication No. 10-338880 and compounds with a triazine ring skeleton as described in International Patent Publication No. 2017 / 170483, as well as compounds containing two or more ethylene oxide groups. These may also include nitrogen-containing compounds such as N,N,N',N'-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, N,N,N',N'-tetraglycidyl-p-phenylenediamine, and compounds shown in formulas (r-1) to (r-3) below.

[0175]

[0176] Specific examples of compounds having oxetane groups include compounds having two or more oxetane groups as described in paragraphs

[0170] to

[0175] of International Publication No. 2011 / 132751.

[0177] Specific examples of compounds having protected isocyanate groups include: compounds having two or more protected isocyanate groups as described in paragraphs

[0046] to

[0047] of Japanese Patent Application Publication No. 2014-224978, compounds having three or more protected isocyanate groups as described in paragraphs

[0119] to

[0120] of International Publication No. 2015 / 141598, and compounds with the following formulas (bi-1) to (bi-3).

[0178]

[0179] As a specific example of a compound having a protected isothiocyanate group, compounds having two or more protected isothiocyanate groups as described in Japanese Patent Application Publication No. 2016-200798 can be cited.

[0180] As a specific example of a compound having a group containing an oxazoline ring structure, the compound containing two or more oxazoline structures described in paragraph

[0115] of Japanese Patent Application Publication No. 2007-286597 can be cited.

[0181] As a specific example of a compound having a group containing a Michaelis acid structure, the compound having two or more Michaelis acid structures described in International Publication No. 2012 / 091088 can be cited.

[0182] As a specific example of a compound having a cyclic carbonate group, the compound described in International Publication No. 2011 / 155577 can be cited.

[0183] Specific examples of hydroxyalkylamide compounds other than those shown in formulas (1) and (1') above include: compounds described in paragraph

[0058] of International Publication No. 2015 / 072554, Japanese Patent Application Publication No. 2016-118753, Japanese Patent Application Publication No. 2016-200798, and International Publication No. 2019 / 142927, as well as compounds shown in formulas (hd-1) to (hd-8) and formulas (hd1-1) to (hd1-4) below.

[0184]

[0185] Examples of (m+n) valence organic groups with aromatic rings in A of formula (e) above include: (m+n) valence aromatic hydrocarbon groups with 6 to 30 carbon atoms; (m+n) valence organic groups formed by direct or linked groups of aromatic hydrocarbon groups with 6 to 30 carbon atoms; and (m+n) valence groups with aromatic heterocycles. Examples of such aromatic hydrocarbons include benzene and naphthalene. Examples of such aromatic heterocycles include: pyrrole rings, imidazole rings, pyrazole rings, pyridine rings, pyrimidine rings, quinoline rings, isoquinoline rings, carbazole rings, pyridazine rings, pyrazine rings, benzimidazole rings, indole rings, quinoxaline rings, and acridine rings. Examples of the linking groups mentioned above include: alkylene groups having 1 to 10 carbon atoms, -NR- (where R is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms), alkylene groups having 1 to 10 carbon atoms and containing a fluorine atom, groups formed by removing one hydrogen atom from the aforementioned alkylene groups, divalent or trivalent cyclohexane rings, etc. It should be noted that any hydrogen atom of the aforementioned alkylene groups may optionally be replaced by a fluorine atom or an organic group such as trifluoromethyl. Specific examples include the compounds described in International Publication No. 2010 / 074269 and the compounds shown in formulas (e-1) to (e-10) below.

[0186]

[0187] The above-described compound is an example of a cross-linking compound, but is not limited thereto. For example, other components not described above may be listed in International Publication No. 2015 / 060357, pages 53

[0105] to 55

[0116] . Furthermore, two or more cross-linking compounds may be combined.

[0188] The content of the crosslinking compound in the liquid crystal alignment 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 alignment agent, and more preferably 1 to 15 parts by mass from the viewpoint that the crosslinking reaction is carried out and good resistance to AC image retention is exhibited.

[0189] Examples of such sealing agents include: 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureopropyltrimethoxysilane, 3-ureopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxy 3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonylacetate, 9-triethoxysilyl-3,6-diazanonylacetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane Alkane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis(oxyethylidene)-3-aminopropyltrimethoxysilane, N-bis(oxyethylidene)-3-aminopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-epoxypropoxypropylmethyldimethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-epoxypropoxypropyl Silane coupling agents include oxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, tri-(trimethoxysilylpropyl)isocyanurate, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-isocyanatopropyltriethoxysilane. When using silane coupling agents, from the viewpoint of exhibiting good resistance to AC image retention, the amount of polymer component contained in the liquid crystal alignment agent is preferably 0.1 to 30 parts by weight, more preferably 0.1 to 20 parts by weight per 100 parts by weight.

[0190] (Liquid crystal alignment film)

[0191] The liquid crystal alignment film of the present invention is formed using the liquid crystal alignment agent of the present invention described above.

[0192] As a preferred embodiment of the manufacturing method of the liquid crystal alignment film of the present invention, for example, a manufacturing method of the liquid crystal alignment film including the following steps can be listed: a step of coating the above-mentioned liquid crystal alignment agent onto a substrate (step (1)); a step of firing the coated liquid crystal alignment agent (step (2)); and a step of aligning the film obtained in step (2) as appropriate (step (3)).

[0193] <Process (1)>

[0194] As for the substrate used in this invention for coating the liquid crystal alignment agent, there are no particular limitations as long as it is a highly transparent substrate; glass substrates, silicon nitride substrates, acrylic substrates, polycarbonate substrates, and other plastic substrates can be used. In this case, using a substrate with ITO electrodes for driving the liquid crystal is preferable from the perspective of process simplification. Furthermore, in reflective liquid crystal display elements, if it is only a single-sided substrate, an opaque material such as a silicon wafer can be used, and in this case, the electrodes can be made of light-reflecting materials such as aluminum.

[0195] Methods for forming a film by coating a liquid crystal alignment agent onto a substrate include screen printing, offset printing, flexographic printing, inkjet printing, and spraying. Among these, inkjet printing is preferred.

[0196] <Process (2)>

[0197] Step (2) is a step of forming a film by firing the liquid crystal alignment agent coated on the substrate. The liquid crystal alignment agent can be coated onto the substrate, and the solvent can be evaporated by a heating unit such as a heating plate, a thermally circulating oven, or an IR (infrared) oven; or thermal imidization of the amyl acid or amyl ester in the polymer can be performed. The drying and firing steps after coating with the liquid crystal alignment agent of the present invention can be performed at any temperature and time, and can be repeated multiple times. For example, the temperature at which the solvent of the liquid crystal alignment agent evaporates can be 40–180°C. From the viewpoint of shortening the process, it can also be performed at 40–150°C. The firing time is not particularly limited, but examples include 1–10 minutes or 1–5 minutes. In the case of thermal imidization of the amyl acid or amyl ester in the polymer, a firing step can be performed, for example, at a temperature range of 150–300°C or 150–250°C after the step of evaporating the above-mentioned organic solvent. The firing time is not particularly limited, but examples include 5–40 minutes or 5–30 minutes.

[0198] If the film after firing is too thin, the reliability of the liquid crystal display element may sometimes be reduced. Therefore, 5 to 300 nm is preferred, and 10 to 200 nm is more preferred.

[0199] <Process (3)>

[0200] Step (3) is a step of aligning the film obtained in step (2) as appropriate. That is, in vertically aligned liquid crystal display elements such as VA mode or PSA mode, the formed coating film can be used directly as a liquid crystal alignment film, or the coating film can be subjected to an alignment capability imparting treatment. As an alignment treatment method for liquid crystal alignment film, a rubbing treatment method can be used, but a photo-alignment treatment method is preferred. As a photo-alignment treatment method, the following method can be listed: the surface of the above-mentioned film is irradiated with radiation of a fixed direction bias, and, as appropriate, a heating treatment is preferably performed at a temperature of 150 to 250°C to impart liquid crystal alignment properties (also known as liquid crystal alignment capability). As radiation, ultraviolet light or visible light with a wavelength of 100 to 800 nm can be used. Among them, ultraviolet light with a wavelength of 100 to 400 nm is preferred, and ultraviolet light with a wavelength of 200 to 400 nm is more preferred.

[0201] The preferred radiation dose is 1–10,000 mJ / cm². 2 The preferred concentration is 100–5000 mJ / cm³. 2 Furthermore, to improve liquid crystal alignment when irradiated with radiation, the substrate having the above-mentioned film can be irradiated while being heated at 50–250°C. The liquid crystal alignment film produced in this way allows the liquid crystal molecules to be stably aligned in a fixed direction.

[0202] Furthermore, in the above methods, water or solvents can be used to contact the liquid crystal alignment film irradiated with polarized radiation, or the liquid crystal alignment film irradiated with radiation can be heated.

[0203] The solvent used in the above-described contact treatment is not particularly limited as long as it can dissolve the decomposition products generated by radiation exposure on the film. 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, etc. Among these, water, 2-propanol, 1-methoxy-2-propanol, or ethyl lactate are preferred from the perspective of versatility and solvent safety. Water, 1-methoxy-2-propanol, or ethyl lactate are more preferred. One solvent or a combination of two or more solvents can be used.

[0204] Examples of the contact treatments described above include immersion treatment and spray treatment (also known as coating treatment). From the perspective of efficiently dissolving the decomposition products generated from the film by radiation irradiation, the treatment time in these treatments is preferably 10 seconds to 1 hour. Immersion treatment for 1 to 30 minutes is preferred. Furthermore, the solvent used in the above contact treatments can be at room temperature or heated, preferably 10 to 80°C. Preferably, it is 20 to 50°C. In addition, from the perspective of the solubility of the decomposition products, ultrasonic treatment or the like can be performed as needed.

[0205] After the above contact treatment, it is preferable to perform rinsing (also called washing) and firing using low-boiling-point solvents such as water, methanol, ethanol, 2-propanol, acetone, and methyl ethyl ketone. At this time, either rinsing or firing, or both, can be performed. The firing temperature is preferably 150–300°C, more preferably 180–250°C, and even more preferably 200–230°C. Furthermore, the firing time is preferably 10 seconds to 30 minutes, preferably 1 to 10 minutes.

[0206] The heat treatment of the coating irradiated with the above-mentioned radiation is more preferably performed at 50 to 300°C for 1 to 30 minutes, and even more preferably at 120 to 250°C for 1 to 30 minutes.

[0207] (Liquid crystal display element)

[0208] The liquid crystal display element of the present invention has the liquid crystal alignment film of the present invention.

[0209] From the viewpoint of obtaining high liquid crystal alignment, the liquid crystal alignment film of the present invention is preferably used as a liquid crystal alignment film for liquid crystal display elements of lateral electric field type such as IPS type and FFS type, and in particular, it is useful as a liquid crystal alignment film for liquid crystal display elements of FFS type.

[0210] Liquid crystal display elements can be manufactured as follows: After obtaining a substrate with a liquid crystal alignment film obtained by the liquid crystal alignment agent of the present invention, a liquid crystal cell is fabricated by a known method, and liquid crystal is disposed within the liquid crystal cell. Specifically, the following two methods can be listed. The first method is to first arrange two substrates facing each other with their respective liquid crystal alignment films facing each other and separated by a gap (cell gap). Next, the peripheral portions of the two substrates are bonded together with a sealant, and a liquid crystal composition is injected into the cell gap defined by the substrate surface and the sealant until it contacts the film surface, and then the injection hole is sealed.

[0211] Furthermore, a second method is known as the ODF (One Drop Fill) method. In this method, a UV-curable sealant is applied, for example, to a predetermined location on one of the two substrates on which the liquid crystal alignment film has been formed. Then, a liquid crystal composition is dropped onto several predetermined locations on the surface of the liquid crystal alignment film. The other substrate is then bonded with the liquid crystal alignment film facing each other, and the liquid crystal composition is spread across the entire surface of the substrate, contacting the film surface. Next, the entire surface of the substrate is irradiated with UV light to cure the sealant. Regardless of the method used, it is ideal to further heat the liquid crystal composition to a temperature that makes it isotropic, and then slowly cool it to room temperature, thereby removing the flow alignment during liquid crystal filling.

[0212] It should be noted that when the coating has undergone a friction treatment, the two substrates are arranged at a predetermined angle to each other, for example, in an orthogonal or antiparallel manner, with the friction directions in each coating being opposite each other. Similarly, when a photo-alignment treatment has been performed, the substrates are arranged at a predetermined angle to each other, for example, in an orthogonal or antiparallel manner, with the alignment directions being opposite each other.

[0213] As a sealant, for example, epoxy resin containing a curing agent and alumina spheres as spacers can be used. Examples of liquid crystals include nematic liquid crystals and smectic liquid crystals, with nematic liquid crystals being preferred.

[0214] The liquid crystal material can be any type of positive or negative liquid crystal material, with a negative liquid crystal material being preferred. Next, polarizers are installed. Specifically, a pair of polarizers are attached to the surfaces of the two substrates opposite to the liquid crystal layer. Examples of polarizers include: a polarizer consisting of a cellulose acetate protective film sandwiching a polarizing film called an "H film" that aligns polyvinyl alcohol while absorbing iodine; or a polarizer consisting of the H film itself.

[0215] Example

[0216] The following examples illustrate the invention in further detail, but the invention is not limited thereto. The abbreviations of the compounds and the methods for determining their properties are described below. Furthermore, "Boc" represents tert-butyloxycarbonyl.

[0217] (Organic solvents)

[0218] NMP: N-methyl-2-pyrrolidone.

[0219] GBL: γ-Butyrolactone.

[0220] BCS: Butyl cellosolve.

[0221] DMF: N,N-dimethylformamide.

[0222] (Diamine)

[0223] DA-1 to DA-6: These are compounds represented by the formulas (DA-1) to (DA-6) below.

[0224] (Tetracarboxylic acid dianhydride)

[0225] DAH-1 to DAH-2: These are compounds represented by the formulas (DAH-1) to (DAH-2) below.

[0226] (Cross-linking agent)

[0227] AD-1: The compound represented by the following formula (AD-1).

[0228] AD-2: The compound shown in the following formula (AD-2). This compound was synthesized by the synthetic method described in Japanese Patent Publication No. 2018-537481 (paragraphs

[0079] to

[0080] , Figure 5).

[0229] AD-3: The compound represented by the following formula (AD-3).

[0230]

[0231]

[0232] [Viscosity]

[0233] The viscosity of the polyamic acid solution was measured using an E-type viscometer (Toki Sangyo Co., Ltd., TVE-22H) with a sample volume of 1.1 mL, a conical rotor TE-1 (1°34', R24), and at a temperature of 25°C.

[0234] [Synthesis of monomers]

[0235] The synthesis of AD-3, a novel compound, is described in detail below.

[0236] The product described in the following synthetic example 1 is obtained by... 1 Identification was performed using H-NMR analysis (analytical conditions are described below).

[0237] Device: BRUKER ADVANCE III – 500MHz.

[0238] Determination solvent: deuterated dimethyl sulfoxide (DMSO-d6).

[0239] Reference material: Tetramethylsilane (TMS) (δ 0.0 ppm for 1 H).

[0240] (Synthetic Example 1: Synthesis of AD-3)

[0241] AD-3 was synthesized according to the following scheme.

[0242]

[0243] <Synthesis of AD-3-1>

[0244] Succinic anhydride (13.0 g, 130 mmol), dichloromethane (60 g), and 4-dimethylaminopyridine (3.14 g, 25.7 mmol) were added to tetraethylene glycol (10.0 g, 51.5 mmol), and the mixture was heated under reflux at 50 °C for 6 hours. After the reaction was completed, the mixture was cooled to room temperature (25 °C), and the solution was washed twice with 2N hydrochloric acid (60 g). The solution was then concentrated and dried to obtain AD-3-1 (yield: 15.6 g, 39.6 mmol, 77% yield).

[0245] 1 H-NMR (500MHz) 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).

[0246] <Synthesis of AD-3-2>

[0247] Dichloromethane (94 g), oxalyl chloride (10.4 g, 81.9 mmol), and DMF (0.16 g) were added to AD-3-1 (15.6 g, 39.6 mmol), and the mixture was stirred at 25°C for 5 hours. After the reaction was complete, the solution was concentrated to obtain crude AD-3-2 (yield: 18 g). The crude AD-3-2 was used directly in the next process.

[0248] <Synthesis of AD-3>

[0249] Dichloromethane (86 g) and triethylamine (8.82 g, 87.2 mmol) were added to bis(2-((trimethylsilyl)oxy)ethyl)amine (20.8 g, 83.3 mmol), and the mixture was cooled to 0 °C in an ice bath. The crude product of AD-3-2 (18 g), diluted with dichloromethane (34 g), was added dropwise. After the addition was complete, the mixture was stirred at 25 °C for 17 hours. The precipitated triethylamine hydrochloride was removed by filtration. The addition of water emulsified the product, significantly worsening its segregation properties; therefore, total concentration, including the aqueous phase, was performed. When methanol was added to the crude product, the target compound dissolved, and salt precipitated; therefore, filtration / concentration was performed. This process was repeated three times, with salt removal by filtration. Methanol (108 g) and acetic acid (0.030 g) were added to the crude product, 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 repeatedly azeotropically treated to remove acetic acid. Acetonitrile and specially prepared Bailu activated carbon were then added, and the mixture was heated and stirred at 80°C before filtration and concentration. This process was repeated twice, followed by drying to obtain AD-3 (yield: 13.1 g, 23.0 mmol, two-stage yield 58%).

[0250] 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).

[0251] [Polymer Synthesis]

[0252] (Manufacturing Example 1)

[0253] DA-1 (1.08 g, 10 mmol), DA-2 (3.66 g, 15 mmol), DA-3 (4.81 g, 15 mmol), and DA-4 (3.98 g, 10 mmol) were added to a 200 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube. Then, NMP (132 g) was added, and the mixture was stirred while adding nitrogen to dissolve the diamine solution. DAH-1 (10.54 g, 47 mmol) was added while stirring the solution, followed by NMP (40.3 g). The mixture was then stirred further at 40 °C for 12 hours, yielding a polyamic acid solution (PAA-1) with a solid content of 12% by mass. The viscosity of this polyamic acid solution was 430 mPa·s.

[0254] (Manufacturing Example 2)

[0255] DA-5 (3.99 g, 20 mmol) and DA-6 (1.49 g, 5.0 mmol) were measured into a 100 mL four-necked flask equipped with a stirrer and a nitrogen inlet tube. Then, 49 g of NMP was added, and the solution was dissolved by stirring while adding nitrogen. DAH-2 (4.71 g, 24 mmol) was added while stirring the diamine solution, and NMP was further added at a solids concentration of 10% by mass. The mixture was stirred at room temperature for 20 hours to obtain a polyamic acid solution (PAA-2) (viscosity: 150 mPa·s).

[0256] [Preparation of Sample Solution]

[0257] (Comparative Example 1)

[0258] 1.33 g of the polyamic acid solution (PAA-1) obtained in Manufacturing Example 1 was measured into a 50 mL Erlenmeyer flask equipped with a stir bar, and 2.40 g of the polyamic acid solution (PAA-2) obtained in Manufacturing Example 2 was added. Then, 0.27 g of NMP, 2.20 g of GBL, 3.00 g of BCS, and 0.80 g of a 10% NMP solution of AD-1 were added, and the mixture was stirred overnight with a magnetic stirrer to obtain the liquid crystal alignment agent (AL-1).

[0259] (Examples 1-2)

[0260] AD-2 to AD-3 were used instead of AD-1, and the same operation as in Comparative Example 1 was performed to obtain liquid crystal alignment agents (AL-2) to (AL-3).

[0261] (Comparative Example 2)

[0262] Add 10% NMP solution (1.20 g) of AD-1 to a 50 mL Erlenmeyer flask with a stir bar, then add NMP (2.80 g), GBL (3.00 g) and BCS (3.00 g), and stir overnight with a magnetic stirrer to obtain solution (Sol-1).

[0263] (Examples 3-4)

[0264] AD-2 to AD-3 were used instead of AD-1, and the same operation as in Comparative Example 2 was performed to obtain solutions (Sol-2) to (Sol-3).

[0265] [Evaluation of Liquid Crystal Alignment Agents]

[0266] The following evaluation of image retention and abrasion resistance tests were conducted on liquid crystal alignment films formed using the liquid crystal alignment agents of Comparative Example 1 and Examples 1-2, respectively, and on liquid crystal elements having the liquid crystal alignment films.

[0267] <Making of LCD Cells>

[0268] A liquid crystal cell with an FFS mode liquid crystal display element was manufactured.

[0269] First, a substrate with electrodes was prepared. The substrate was a rectangular glass substrate measuring 30mm × 35mm with a thickness of 0.7mm. On the substrate, as the first layer, an ITO electrode with a full-surface pattern constituting the counter electrode was formed. On the counter electrode of the first layer, as the second layer, a SiN (silicon nitride) film formed by CVD was formed. The SiN film of the second layer was a 500nm thick film that served as an interlayer insulating film. On the SiN film of the second layer, as the third layer, a comb-shaped pixel electrode formed by patterning the ITO film was disposed, forming the first pixel and the second pixel. Each pixel is approximately 10mm long and 5mm wide. At this point, the counter electrode of the first layer and the pixel electrode of the third layer are electrically insulated by the SiN film of the second layer.

[0270] The pixel electrode of the third layer has a comb-like shape formed by multiple 3μm wide electrode elements arranged in parallel with a 6μm interval, which are bent at an inner angle of 160° in the central part. A pixel has a first region and a second region bounded by the line connecting the bent portions of the multiple electrode elements.

[0271] Next, the liquid crystal alignment agents (AL-1) to (AL-3) obtained in Comparative Example 1 and Examples 1-2 were filtered using a 1.0 μm pore size filter and then spin-coated onto the prepared electrode substrate and a glass substrate with columnar spacers having a height of 4 μm and an ITO film on the back side. After drying on a hot plate at 80°C for 2 minutes, the coating was fired in an IR oven at 230°C for 30 minutes to form a coating with a thickness of 100 nm. The desired viscosity was 300 mJ / cm³. 2 The coated surface was irradiated with polarized ultraviolet light to perform alignment treatment. It was then fired again in an IR oven at 230°C for 30 minutes to obtain a substrate with a liquid crystal alignment film. The two substrates were grouped together, and a sealant (Mitsui Chemicals XN-1500T) was printed around the liquid crystal injection port. Another substrate was then bonded with the liquid crystal alignment film facing each other and the alignment direction at 0°, and the sealant was cured to create an empty cell. Liquid crystal MLC-3019 (MERCK) was injected into this empty cell using a depressurized injection method, and the injection port was sealed to obtain an FFS-driven liquid crystal cell.

[0272] The FFS-driven liquid crystal cell obtained as described above was heated at 110°C for 1 hour and left overnight. The following image retention evaluation was then performed.

[0273] <Afterimage Evaluation Based on Long-Term Communication>

[0274] Under a constant temperature environment of 60°C, an AC voltage of ±5V at a frequency of 30Hz was applied to the above-mentioned FFS-driven liquid crystal cell for 120 hours (it should be noted that, hereinafter, "FFS-driven liquid crystal cell" will also be referred to as "liquid crystal cell"). Then, the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited, and this state was maintained at room temperature for one day.

[0275] After placement, the liquid crystal cell is positioned between two polarizers orthogonally arranged with their polarization axes aligned. The backlight is illuminated without applied voltage, and the cell's orientation angle is adjusted to minimize the transmitted light brightness. Then, the rotation angle Δ is calculated to allow the liquid crystal cell to rotate from the darkest angle of the second region of the first pixel to the darkest angle of the first region. The same angle Δ is calculated for the second pixel by comparing the second region with the first region. Finally, the average of the angles Δ for the first and second pixels is calculated as the liquid crystal cell's angle Δ.

[0276] Angles Δ of 0.10° or greater for the obtained liquid crystal cell are rated as “×”, and angles less than 0.10° are rated as “〇”.

[0277] <Abrasion Resistance Test>

[0278] Next, in order to confirm the strength of the liquid crystal alignment film formed using the liquid crystal alignment agent obtained in Examples 1-2 and Comparative Example 1, a friction resistance test was conducted.

[0279] The liquid crystal alignment agents (AL-1) to (AL-3) obtained in Comparative Example 1 and Examples 1-2 were spin-coated onto the ITO surface of a glass substrate with ITO electrodes covering the entire surface. After drying on a hot plate at 80°C for 2 minutes, the substrate was fired in an IR oven at 230°C for 30 minutes to form a coating film with a thickness of 100 nm. The surface area of ​​this coating film was measured to have a strength of 300 mJ / cm². 2 The substrate was irradiated with polarized ultraviolet light to perform an alignment process. It was then fired again in an IR oven at 230°C for 30 minutes to obtain a substrate with a liquid crystal alignment film.

[0280] The substrate with the liquid crystal alignment film obtained above was rubbed with rayon cloth (roller diameter: 120 mm, roller speed: 1000 rpm, moving speed: 20 mm / sec, pressing length: 0.6 mm), and then the abrasion resistance of the liquid crystal alignment film was evaluated by microscopic observation.

[0281] Samples in which no friction-induced stripes are observed on the film surface will be rated as "○", and samples in which stripes are observed will be rated as "×".

[0282] The evaluation results of image retention evaluation for FFS-driven liquid crystal cells in Comparative Example 1 and Examples 1-2, and the evaluation results of abrasion resistance test of liquid crystal alignment film are shown in Table 1 below.

[0283] [Table 1]

[0284] Types of crosslinking agents Liquid crystal alignment agent Afterimage Evaluation abrasion resistance Comparative Example 1 AD-1 AL-1 ○ ○ Example 1 AD-2 AL-2 ○ ○ Example 2 AD-3 AL-3 ○ ○

[0285] To confirm whether the liquid crystal alignment agent is a liquid crystal alignment agent in which the solid components do not precipitate when stored at low temperature, the following low temperature storage stability test was conducted using the crosslinking agent solutions (Sol-1) to (Sol-3) of Comparative Example 2 and Examples 3 to 4.

[0286] <Low-Temperature Storage Stability Test>

[0287] The crosslinking agent solutions (Sol-1) to (Sol-3) obtained in Comparative Example 2 and Examples 3 to 4 were subjected to a test to evaluate their low-temperature storage stability by placing them at -20°C for 2 days.

[0288] The precipitation state of the solution was observed after 2 days. If no precipitation was observed, the solution was judged to have good stability for practical low-temperature storage, and was rated "○". On the other hand, if precipitation was observed, the solution was judged to have poor stability for low-temperature storage, and was rated "×". The results are shown in Table 2 below.

[0289] [Table 2]

[0290] Types of crosslinking agents Crosslinking agent solution Low temperature storage stability Comparative Example 2 AD-1 Sol-1 × Example 3 AD-2 Sol-2 ○ Example 4 AD-3 Sol-3 ○

[0291] As shown in Tables 1 and 2, it can be seen that AD-2, which has an alkyl amide site and an alkyl group on the N of the amide group, or AD-3, which has an alkyl amide site and an ethylene glycol chain, can impart good liquid crystal orientation and high abrasion resistance when used as an orientation agent, and can form an orientation agent with excellent low-temperature storage stability.

[0292] Industrial availability

[0293] The liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention is suitable for use in various liquid crystal display elements, including those using IPS driving and FFS driving methods. Furthermore, these display elements are not limited to liquid crystal displays intended for display purposes; they are also useful in dimming windows, optical shutters, and the like, which control the transmission and blocking of light.

Claims

1. A liquid crystal alignment agent comprising the following components (A) and (B), (A) Composition: A polymer (A) having the ability to orient liquid crystals, wherein the polymer (A) is at least one polymer selected from the group consisting of a polyimide precursor and a polyimide as an imide derivative of the polyimide precursor; (B) Ingredient: Hydroxyalkylamide compound (B). The hydroxyalkylamide compound (B) is any compound from the compounds shown in formulas (b-1) to (b-3) below. 。 2. A liquid crystal alignment agent comprising the following components (A') and (B'), (A') Composition: A polymer (A') having the ability to orient liquid crystals, wherein the polymer (A') is at least one polymer selected from the group consisting of a polyimide precursor and a polyimide as an imide derivative of the polyimide precursor; (B') Component: Hydroxyalkylamide compound (B') as shown in formula (1') below. In formula (1'), R' represents the group "*-C(R 2’ )2-C(R 1’ The monovalent organic group shown is 2-OH, wherein... * indicates a bond; R 1’ R 2’ Each R' independently represents a monovalent organic group having 1 to 6 hydrogen or carbon atoms, and the multiple R's may optionally be the same or different; n is an integer from 1 to 20; L 1’ It is a divalent organic group with 1 to 10 carbon atoms, and multiple L 1’ They can be either the same or different.

3. The liquid crystal alignment agent according to claim 2, wherein, The hydroxyalkylamide compound (B') is any compound from the compounds shown in formulas (b'-1) to (b'-5) below. 。 4. The liquid crystal alignment agent according to claim 1 or 2, wherein, The polyimide precursor is obtained using a tetracarboxylic acid component containing a tetracarboxylic acid dianhydride as shown in formula (2). In equation (2), X represents a structure selected from the following equations (x-1) to (x-13). In equations (x-1)~(x-13), R 1 ~R 4 Each of the following can independently represent a hydrogen atom, a halogen atom, an alkyl group with 1 to 6 carbon atoms, an alkenyl group with 2 to 6 carbon atoms, an alkynyl group with 2 to 6 carbon atoms, a monovalent organic group containing a fluorine atom with 1 to 6 carbon atoms, or a phenyl group; R 5 and R 6 Each of the following groups independently represents a hydrogen atom or a methyl group; j and k are integers 0 or 1; A1 and A2 independently represent a single bond, -O-, -CO-, -COO-, phenylene, sulfonyl, or amide group; multiple A2 groups may be the same or different; *1 is a bond bonded to an anhydride group on one side, and *2 is a bond bonded to an anhydride group on the other side.

5. The liquid crystal alignment agent according to claim 4, wherein, The expression (x-1) is selected from the group consisting of the following expressions (x1-1) to (x1-6). In formulas (x1-1) to (x1-6), *1 is a bond bonded to an anhydride group on one side, and *2 is a bond bonded to an anhydride group on the other side.

6. The liquid crystal alignment agent according to claim 1 or 2, wherein, The polyimide precursor is obtained using a diamine component containing a diamine selected from at least one of the diamines shown in formulas (3) and (3i). In formulas (3) and (3i), Y3 represents a divalent organic group as shown in formula (O) below; R represents an alkyl group with 1 to 6 carbon atoms; Y 3i This represents the divalent organic group represented by the following formula (O'). In formula (O), Ar represents a divalent benzene ring, a biphenyl structure, or a naphthalene ring; the two Ars may be the same or different, and any hydrogen atom of the ring may be substituted with a monovalent substituent; p is an integer 0 or 1; Q3 represents -(CH2). n - or - (CH2) n A group consisting of at least a portion of -CH2- replaced by any one of -O-, -C(=O)-, or -O-C(=O)-, where * indicates a bond, and the -(CH2-) group is... n - In this context, n is an integer from 2 to 18; In formula (O'), Ar' represents a divalent benzene ring or a biphenyl structure; the two Ar's may be identical or different, and any hydrogen atom of the ring may be substituted with a monovalent substituent; p' is an integer 0 or 1; Q 3’ It represents - (CH2) n - or - (CH2) n A group consisting of at least a portion of -CH2- replaced by any one of -O-, -C(=O)-, or -O-C(=O)-, where * indicates a bond, and the -(CH2-) group is... n - In this context, n is an integer from 2 to 18.

7. The liquid crystal alignment agent according to claim 6, wherein, The divalent organic group represented by formula (O) is any one of the following formulas (o-1) to (o-16). The "*" in the formula represents the bonding position.

8. The liquid crystal alignment agent according to claim 1 or 2, wherein, The polyimide precursor is obtained using a diamine component containing a diamine having at least one nitrogen-containing structure selected from the group consisting of nitrogen-containing heterocycles, secondary amino groups, and tertiary amino groups, excluding the imide ring present in the polyimide.

9. A method for manufacturing a liquid crystal alignment film, wherein, The liquid crystal alignment agent as described in any one of claims 1 to 8 is coated onto a substrate, fired, and the resulting film is irradiated with polarized radiation.

10. The method for manufacturing a liquid crystal alignment film according to claim 9, wherein, Firing is carried out at a temperature of 150–250°C.

11. A liquid crystal alignment film formed from a liquid crystal alignment agent as described in any one of claims 1 to 8.

12. A liquid crystal display element comprising the liquid crystal alignment film as described in claim 11.

13. The liquid crystal display element according to claim 12, wherein, The liquid crystal display element is driven by either in-plane switching IPS or edge field switching FFS.

Images