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

Abstract

Provided are a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element for optical alignment that can suppress afterimages caused by long-term AC driving in liquid crystal display elements of IPS drive mode and FFS drive mode. 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, wherein the liquid crystal alignment agent is characterized in that it contains a polyimide, wherein the polyimide is an imide compound of a polyimide precursor obtained by a polymerization reaction of a tetracarboxylic acid component and a diamine component, wherein the tetracarboxylic acid component contains: a tetracarboxylic dianhydride or a derivative thereof represented by the following formula (1), a tetracarboxylic dianhydride or a derivative thereof represented by the following formula (2), and an aromatic tetracarboxylic dianhydride represented by the following formula (6). (X1 is any one of formulas (X1‑1) to (X1‑4), X2 is formula (X2‑1) or (X2‑2), and X3 is a tetravalent aromatic ring group.)

Description

Technical Field

[0001] The present invention relates to a liquid crystal aligning agent, a liquid crystal aligning film obtained from the liquid crystal aligning agent, and a liquid crystal display element including the obtained liquid crystal aligning film. Background Art

[0002] Liquid crystal display elements used in liquid crystal televisions, liquid crystal displays, and the like generally have a liquid crystal alignment film provided inside the element for controlling the alignment state of liquid crystals.

[0003] The most popular liquid crystal alignment film in industry is currently produced by a so-called brushing process in which a surface of a film made of polyamic acid and / or polyimide imidized therefrom formed on an electrode substrate is rubbed in one direction with a cloth such as cotton, nylon, or polyester.

[0004] Brushing is a simple and highly productive method that is useful in industry. However, as liquid crystal display elements become more high-performance, high-precision, and large-scale, various problems such as surface damage, dusting, mechanical force, and static electricity of the alignment film generated during brushing, and non-uniformity within the alignment treatment surface have become apparent.

[0005] As a method to replace the brushing treatment, a photo-alignment method is known that imparts liquid crystal alignment capability by irradiating polarized radiation. For treatments based on the photo-alignment method, treatments utilizing photoisomerization reactions, treatments utilizing photocrosslinking reactions, and treatments utilizing photodecomposition reactions have been proposed (see Non-Patent Document 1).

[0006] Patent Document 1 proposes using a polyimide film having an alicyclic structure such as a cyclobutane ring in the main chain for a photo-alignment method.

[0007] The photo-orientation method as described above, as an orientation treatment method without brush grinding, can not only be produced industrially with a simple manufacturing process, but also in the liquid crystal display elements of IPS drive mode and FFS (fringe field switching) drive mode, it can be expected that the contrast and viewing angle characteristics of the liquid crystal display elements will be improved compared with the liquid crystal orientation film obtained by the brush grinding treatment method. Therefore, it has attracted attention as a promising liquid crystal orientation treatment method.

[0008] The liquid crystal alignment film used for the liquid crystal display element of the IPS drive method and the FFS drive method is required not only to have excellent basic characteristics such as liquid crystal alignment and electrical characteristics but also to suppress image sticking due to long-term AC drive.

[0009] However, the liquid crystal alignment film obtained by the photo-orientation method has the following problems: compared with the liquid crystal alignment film obtained by brushing, the anisotropy of the polymer film relative to the orientation direction is small. If the anisotropy is small, sufficient liquid crystal orientation cannot be obtained, and when a liquid crystal display element is made, problems such as residual images will occur. In this regard, in Patent Document 2, as a method for improving the anisotropy of the liquid crystal alignment film obtained by the photo-orientation method, it is proposed to remove the low molecular weight component generated by cutting the main chain of the polyimide by light irradiation after light irradiation.

[0010] Prior art literature

[0011] Patent Literature

[0012] Patent Document 1: Japanese Patent Application Laid-Open No. 9-297313

[0013] Patent Document 2: Japanese Patent Application Publication No. 2011-107266

[0014] Non-patent literature

[0015] Non-patent document 1: "Liquid crystal photo-alignment film" Kidowaki and Ichimura Functional Materials, November 1997, Vol. 17, No. 11, pp. 13-22 Summary of the invention

[0016] Problem that the invention aims to solve

[0017] In the past, when photo-orientation treatment is performed on organic films such as polyimide precursors and polyimide, according to the insights of the present inventors, it is clear that the effect of photo-orientation is sensitive to the amount of light used and requires an optimal amount of light in a relatively narrow range. If the amount of light deviates from this optimal range, sometimes part or all of the liquid crystal orientation film is not completely oriented, and stable orientation of the liquid crystal cannot be achieved.

[0018] Furthermore, it was found that, particularly when a large-sized panel is treated by a photo-alignment method, it is difficult to perform photo-alignment irradiation with uniformly controlled light irradiation amount, and as a result, it becomes difficult to perform an alignment treatment by a stable photo-alignment method.

[0019] Therefore, the object of the present invention is to provide a liquid crystal alignment agent that can obtain a stable liquid crystal alignment ability of good quality even in the case of a particularly large panel by extending the range of light irradiation that can obtain a good orientation control ability (hereinafter, also referred to as the optimal irradiation margin.) That is, the object of the present invention is to provide a liquid crystal alignment agent that has a wide range of light irradiation that can stably produce an orientation control ability and can efficiently obtain a high-quality liquid crystal alignment film.

[0020] Solutions for solving problems

[0021] The present inventors have conducted repeated studies and found that the above-mentioned object can be achieved by including a liquid crystal aligning agent having the following gist.

[0022] A liquid crystal alignment agent, characterized in that it contains a polyimide, wherein the polyimide is an imide of a polyimide precursor obtained by a polymerization reaction of a tetracarboxylic acid component and a diamine component, wherein the tetracarboxylic acid component contains: a tetracarboxylic dianhydride or a derivative thereof represented by the following formula (1), a tetracarboxylic dianhydride or a derivative thereof represented by the following formula (2), and an aromatic tetracarboxylic dianhydride represented by the following formula (6).

[0023]

[0024] Here, X1 is a structure represented by any of the following formulae (X1-1) to (X1-4). X2 is a structure represented by the following formulae (X2-1) or (X2-2). X3 is an aromatic ring having four connecting bonds.

[0025]

[0026] R3 to R6 are each independently 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, and they may be the same or different, but at least one of them is not a hydrogen atom. 23 Each is independently 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.

[0027]

[0028] Effects of the Invention

[0029] By using the liquid crystal alignment agent of the present invention, it is possible to obtain a liquid crystal alignment film that can expand the light irradiation margin for excellent photo-alignment treatment that was previously difficult to obtain, and has good afterimage characteristics. Therefore, for the liquid crystal alignment film obtained by the liquid crystal alignment agent of the present invention, the yield rate in liquid crystal panel manufacturing is high, and the afterimage caused by AC driving generated in the liquid crystal display element of the IPS drive mode and FFS drive mode can be reduced, and the IPS drive mode and FFS drive mode liquid crystal display element with excellent afterimage characteristics can be obtained. DETAILED DESCRIPTION

[0030] As described above, the liquid crystal aligning agent of the present invention is characterized in that it contains a polyimide (hereinafter also referred to as a specific polymer) which is an imidate of a polyimide precursor obtained from a tetracarboxylic acid having a specific structure or a tetracarboxylic acid component derivative having a derivative thereof and a diamine component.

[0031] <Specific polymer>

[0032] The specific polymer used in the present invention is a polyimide, which is an imide compound of a polyimide precursor with a specific structure. As a polyimide precursor, as long as it is a polyimide precursor that forms an imide ring by heating or chemical imidization based on a catalyst such as polyamic acid or polyamic acid ester, it is not particularly limited. From the viewpoint of easily heating or chemical imidization, as a polyimide precursor, polyamic acid or polyamic acid ester is more preferably used.

[0033] The imidization ratio of the polyimide is not particularly limited, but is preferably 10 to 100%, more preferably 50 to 100%, and further preferably 50 to 80%.

[0034] Hereinafter, each component as a raw material for forming the above-mentioned specific polymer will be described.

[0035] <Tetracarboxylic acid component>

[0036] As the tetracarboxylic acid component used for polymerization of the specific polymer of the present invention, not only tetracarboxylic dianhydride but also a derivative thereof, tetracarboxylic acid, tetracarboxylic acid dihalide, tetracarboxylic acid dialkyl ester or tetracarboxylic acid dialkyl ester dihalide can be used.

[0037] The tetracarboxylic acid component used in the polymerization of the specific polymer of the present invention contains: tetracarboxylic dianhydride or its derivatives represented by the following formula (1), tetracarboxylic dianhydride or its derivatives represented by the following formula (2), and aromatic tetracarboxylic dianhydride or its derivatives represented by the following formula (6). By containing the tetracarboxylic dianhydride or its derivatives of the above formula (1), the amount of light irradiation required for the photoreaction of the specific polymer can be reduced, and a liquid crystal alignment film showing high liquid crystal orientation can be obtained. By containing the tetracarboxylic dianhydride or its derivatives of the above formula (2), and the tetracarboxylic dianhydride or its derivatives of the above formula (6), the photoreactivity of the specific polymer can be adjusted to obtain a liquid crystal alignment film with a wide irradiation margin.

[0038]

[0039] X1 is a structure represented by any of the following formulae (X1-1) to (X1-4).

[0040]

[0041] R3 to R6 are each independently 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, and at least one of them is not a hydrogen atom. 23Each is independently 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.

[0042] In order to suppress image sticking due to long-term AC driving, X1 is preferably at least one structure selected from any of the structures represented by the following formulae (X1-12) to (X1-16), and the following formula (X1-12) is particularly preferred.

[0043]

[0044] The content ratio of the tetracarboxylic dianhydride or its derivative represented by the above formula (1) is preferably 50 to 98 mol %, more preferably 60 to 93 mol %, further preferably 65 to 87 mol % based on the tetracarboxylic acid component to be reacted with the diamine component.

[0045] In formula (2), X2 is a structure of the following formula (X2-1) or (X2-2).

[0046]

[0047] In order to suppress the afterimage caused by long-term AC driving, X2 is preferably formula (X2-1).

[0048] The content of the tetracarboxylic dianhydride or its derivative represented by the formula (2) is preferably 1 to 30 mol%, more preferably 5 to 25%, and further preferably 10 to 20%, based on 1 mol of all tetracarboxylic acid components.

[0049] X3 is a tetravalent organic group and an aromatic ring having 4 connecting bonds, preferably an aromatic ring having at least one benzene ring or naphthalene ring and having 4 connecting bonds on the benzene ring or naphthalene ring. If a specific example is given, any structure in the following formula (X3-1) to (X3-26) can be listed. When improving the orientation of the liquid crystal, X3 is preferably any of (X3-1), (X3-5) to (X3-11), (X3-14) to (X3-26). Further preferred is a structure in which n is 1 to 4 in (X3-1), (X3-7), and (X3-8), preferably (X3-9) to (X3-10), or (X3-14) to (X3-26).

[0050]

[0051]

[0052] The content ratio of the aromatic tetracarboxylic dianhydride or its derivative represented by the above formula (6) is preferably 1 to 20 mol%, more preferably 2 to 15 mol%, further preferably 3 to 15 mol%, based on 1 mol of the tetracarboxylic acid component.

[0053] The tetracarboxylic acid component used for polymerization of the specific polymer of the present invention may contain tetracarboxylic dianhydride represented by the following formula (7) or a derivative thereof in addition to the above formulas (1), (2) and (6).

[0054]

[0055] Among them, X4 is a tetravalent organic group, which is an organic group other than the above-mentioned X1 to X3, and its structure is not particularly limited. If specific examples are given, the following formulas (X4-1) to (X4-26), tetravalent groups derived from ethylenediaminetetraacetic acid dianhydride, etc. can be listed. When improving the liquid crystal orientation, X4 can be listed as (X4-8) to (X4-12), (X4-17) to (X4-19), (X4-24) to (X4-26).

[0056]

[0057] <Diamine>

[0058] The diamine component used in the production of the specific polymer of the present invention is not particularly limited as long as it is a known diamine. From the viewpoint of suppressing image sticking due to long-term AC driving, it is preferred to contain at least one diamine selected from the following formula (3), the following formula (4) and the following formula (5).

[0059]

[0060] In the above formulae (3) to (5), A1 and A4 each independently represent a single bond, -CO-O-, -OCO-, -NRCO- (R represents a hydrogen atom or a methyl group), -NRCOO- (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), -COS-, -NR1-CO-NR2- (R1 and R2 each independently represent a hydrogen atom or a methyl group), a divalent chain hydrocarbon group having 2 to 20 carbon atoms, or a divalent chain hydrocarbon group. A group (h1) in which -CH2- of the group is replaced by a group selected from -O-, -CO-, -CO-O-, -NRCO- (R represents a hydrogen atom or a methyl group), -NRCOO- (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), -COS-, -NR1-CO-NR2- (R1 and R2 each independently represent a hydrogen atom or a methyl group), -NR- (R represents a methyl group), pyrrolidine, piperidine, and piperazine. It should be noted that a part or all of the hydrogen atoms possessed by the above-mentioned chain hydrocarbon groups of A1 and A4 and the group (h1) may be optionally substituted by a halogen atom such as an alkyl group having 1 to 3 carbon atoms such as a methyl group, a fluorine atom, a chlorine atom, or the like. A2 is a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a mercapto group, a nitro group, a phosphoric acid group, or a monovalent organic group having 1 to 20 carbon atoms. A3 represents a divalent chain hydrocarbon group having 1 to 20 carbon atoms, or a group (h2) formed by replacing -CH2- of the divalent chain hydrocarbon group with a group selected from -O-, -CO-, -CO-O-, -NRCO- (R represents a hydrogen atom or a methyl group), -NRCOO- (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), -COS-, -NR1-CO-NR2- (R1 and R2 each independently represent a hydrogen atom or a methyl group), -NR- (R represents a methyl group), pyrrolidine, piperidine, and piperazine. It should be noted that a part or all of the hydrogen atoms possessed by the above-mentioned chain hydrocarbon group of A3 and the group (h2) may be optionally substituted with a halogen atom such as an alkyl group having 1 to 3 carbon atoms such as a methyl group, a fluorine atom, or a chlorine atom. a is an integer of 1 to 4, and when a is 2 or more, the structure of A2 may be optionally the same or different. b and c are integers of 1 or 2. d is an integer of 0 or 1. )

[0061] Examples of the above-mentioned divalent chain hydrocarbon group having 1 to 20 carbon atoms include alkanediyl groups such as methanediyl, ethanediyl, n-propanediyl, isopropanediyl, n-butanediyl, isobutanediyl, sec-butanediyl, and tert-butanediyl; alkenediyl groups such as ethylenediyl, propylenediyl, and butenediyl; and acetylenediyl, propynylenediyl, and butynylenediyl.

[0062] Examples of the monovalent organic group having 1 to 20 carbon atoms in A2 include a group obtained by adding one hydrogen atom to the group exemplified above, such as a divalent chain hydrocarbon group having 1 to 20 carbon atoms as A3, the group (h2), or a group obtained by replacing a part or all of the hydrogen atoms possessed by the divalent chain hydrocarbon group having 1 to 20 carbon atoms and the group (h2) with an alkyl group having 1 to 3 carbon atoms such as a methyl group, or a halogen atom such as a fluorine atom or a chlorine atom.

[0063] In order to suppress the afterimage caused by long-term AC driving, the following formulas (DA-3-1), (DA-4-1) to (DA-4-24), (DA-5-1) to (DA-5-3) are preferred as the above formula (3) and the above formula (4). Among them, (DA-3-1), (DA-4-1) to (DA-4-11), (DA-4-13) to (DA-4-24), (DA-5-1) to (DA-5-2) are more preferred.

[0064]

[0065]

[0066] The content of the diamine represented by the above formula (3), formula (4) or formula (5) is preferably 50 to 100 mol%, more preferably 70 to 100 mol%, based on 1 mol of the diamine component.

[0067] From the viewpoint of improving the solubility of the polymer, the diamine used for producing the specific polymer of the present invention preferably contains a diamine represented by the following formula (8).

[0068]

[0069] In the above formula (8), Y6 is a divalent organic group having a structure represented by the following formula (9). A6 is each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms. From the viewpoint of liquid crystal orientation, A6 is preferably a hydrogen atom or a methyl group.

[0070]

[0071] D is tert-butoxycarbonyl.

[0072] Specific examples of the divalent organic group including the structure represented by the above (9) include the following formula (J-1) or formula (J-2).

[0073]

[0074] In the above formulae (J-1) and (J-2), *1 represents a bond to NH-A6, Q5 is a single bond, -(CH2)n -(n is an integer of 1 to 20), or -(CH2) n - is a group formed by replacing any -CH2- in - with -O-, -COO-, -OCO-, -NR-, -NRCO-, -CONR-, -NRCONR-, -NRCOO-, or -OCOO-, wherein R represents a hydrogen atom or a monovalent organic group.

[0075] Q6 and Q7 each independently represent a group having -H, -NHD, -N(D)2, -NHD, or a group having -N(D)2. Q8 represents a group having -NHD, -N(D)2, -NHD, or a group having -N(D)2. D represents a tert-butoxycarbonyl group. Among them, at least one of Q5, Q6 and Q7 has a tert-butoxycarbonyl group (Boc). More preferably, it is a divalent organic group represented by the following formula (J-1-a) to (J-1-d) or (J-2-1).

[0076]

[0077] The diamine used for polymerization of the specific polymer of the present invention may contain a diamine represented by the following formula (10) in addition to the above formulas (3) to (5) and (8).

[0078]

[0079] In the above formula (10), A8 is each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms. From the viewpoint of liquid crystal orientation, A8 is preferably a hydrogen atom or a methyl group.

[0080] Y8 is a divalent organic group, and examples thereof include a group represented by any of formulas (Y-1) to (Y-167) described in WO2018 / 117239.

[0081] <Production Method of Polyamic Acid Ester, Polyamic Acid, and Polyimide>

[0082] The polyamic acid ester, the polyamic acid, and the polyimide which are polyimide precursors used in the present invention can be synthesized by a known method described in, for example, International Publication WO2013 / 157586.

[0083] <Liquid Crystal Alignment Agent>

[0084] The liquid crystal aligning agent of the present invention has a solution form in which a polymer component such as a specific polymer is dissolved in an organic solvent. The molecular weight of the specific polymer is preferably 2,000 to 500,000, more preferably 5,000 to 300,000, and further preferably 10,000 to 100,000 in terms of weight average molecular weight. In addition, the number average molecular weight is preferably 1,000 to 250,000, more preferably 2,500 to 150,000, and further preferably 5,000 to 50,000.

[0085] The liquid crystal aligning agent of the present invention is a composition containing the above-mentioned specific polymer and an organic solvent, and may also contain two or more specific polymers of different structures. In addition, the liquid crystal aligning agent of the present invention may also contain a polymer other than the specific polymer (hereinafter also referred to as the second polymer) and various additives.

[0086] When the liquid crystal aligning agent of the present invention contains a second polymer, it is preferable that the ratio of the specific polymer to all polymer components is 5 mass % or more, and as an example thereof, 5 to 95 mass % can be mentioned.

[0087] Examples of the second polymer include polyamic acid, polyimide, polyamic acid ester, polyester, polyamide, polyurea, polyorganosiloxane, cellulose derivatives, polyacetal, polystyrene or its derivatives, poly(styrene-phenylmaleimide) derivatives, and poly(meth)acrylate.

[0088] In particular, a polyamic acid obtained from a tetracarboxylic dianhydride component and a diamine component (hereinafter also referred to as a second polyamic acid) is preferred as the second polymer.

[0089] As a tetracarboxylic acid component for obtaining the 2nd polyamic acid, tetracarboxylic dianhydride represented by following formula (11) is mentioned. This tetracarboxylic dianhydride may be 2 or more types.

[0090]

[0091] In the above formula (11), A is a tetravalent organic group, preferably a tetravalent organic group having 4 to 30 carbon atoms.

[0092] Preferred structures of A are shown below, but the present invention is not limited to these.

[0093]

[0094] Among the above structures, (A-1) and (A-2) are preferred from the viewpoint of further improving the photo-orientation, (A-4) is preferred from the viewpoint of further improving the relaxation rate of charge accumulation, and (A-15) to (A-17) are preferred from the viewpoint of further improving the relaxation rate of liquid crystal orientation and charge accumulation. The tetracarboxylic dianhydride component used to obtain the second polyamic acid may be one tetracarboxylic dianhydride, or two or more tetracarboxylic dianhydrides may be used in combination.

[0095] The diamine component for obtaining the second polyamic acid can be appropriately determined depending on the purpose, and for example, a diamine represented by the following formula (12) can be used.

[0096]

[0097] (Y9 represents a divalent organic group. A9 is independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms. From the viewpoint of liquid crystal orientation, A9 is more preferably a hydrogen atom or a methyl group.)

[0098] For the purpose of improving electrical properties and relaxing properties, Y9 is preferably a divalent organic group having a tertiary nitrogen atom, or a divalent organic group having -NH-CO-NH- in the molecule. Specific examples of formula (12) when Y9 is a divalent organic group having a tertiary nitrogen atom include diamines having a pyrrole structure described in International Publication WO2017 / 126627, preferably diamines represented by the following formula (pr).

[0099]

[0100] In the above formula (pr), R 1 represents a hydrogen atom, hydrogen, a fluorine atom, a cyano group, a hydroxyl group, or a methyl group. 2 Each independently represents a single bond or a group "*1-R 3 -Ph-*2", R 3 represents a single bond, selected from -O-, -COO-, -OCO-, -(CH2) l -、-O(CH2) m O-, -CONH-, and -NHCO- are divalent organic groups (l and m represent integers of 1 to 5), *1 represents a site bonded to a benzene ring in formula (pr), and *2 represents a site bonded to an amino group in formula (pr). Ph represents a phenylene group. n represents 1 to 3.

[0101] Examples include: diamines having a pyrrole structure described in International Publication WO2018 / 062197, and preferably diamines having a structure represented by the following formula (pn):

[0102]

[0103] (R 1 and R 2 Each independently represents a hydrogen atom or a methyl group, R 3 Indicates a single bond or group "*1-R 4 -Ph-*2", R 4 represents a single bond, selected from -O-, -COO-, -OCO-, -(CH2) l -、-O(CH2) m O-, -CONH-, and a divalent organic group in -NHCO- (l and m represent integers of 1 to 5, *1 represents a site bonded to a benzene ring in the formula (pn), and *2 represents a site bonded to an amino group in the formula (pn). Ph represents a phenylene group. n represents 1 to 3.),

[0104] The diamine having a carbazole structure described in International Publication WO2018 / 110354, preferably a diamine having a structure represented by the following formula (cz):

[0105]

[0106] (R 1 represents a hydrogen atom or a methyl group, R 2 Represents a methyl group. ),

[0107] The diamine having a nitrogen-containing heterocyclic ring described in paragraphs

[0173] to

[0188] of International Publication WO2015 / 046374, the diamine having a nitrogen-containing structure described in paragraph

[0050] of JP-A-2016-218149, and the diamine represented by the following formula (BP):

[0108]

[0109] (X is a biphenyl ring or a fluorene ring, Y is a group selected from a benzene ring, a biphenyl ring, or -phenyl-Z-phenyl-, Z is a divalent group represented by -O-, -NH-, -CH2-, -SO2-, -C(CH3)2-, or C(CF3)2-. A and B are hydrogen atoms or methyl groups), 2,3-diaminopyridine, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 5,6-diamino-2,3-dicyanopyrazine, 5,6-diamino-2,4-dihydroxypyrimidine, 2,4-diamino-6-dimethylamino-1,3,5-triazine, 1,4-bis(3-aminopropyl)piperazine, 4,4'-[4,4'-propane-1,3-diylbis(piperidin-1,4-diyl)]diphenylamine, 2,4-diamino-6-isopropoxy-1, 3,5-triazine, 2,4-diamino-6-methoxy-1,3,5-triazine, 2,4-diamino-6-phenyl-1,3,5-triazine, 2,4-diamino-6-methyl-s-triazine, 2,4-diamino-1,3,5-triazine, 4,6-diamino-2-vinyl-s-triazine, 3,5-diamino-1,2,4-triazole, 6,9-diamino-2-ethoxyacridine lactate, 3,8-diamino-6-phenylphenanthridine, 1,4-diaminopiperazine, 3,6-diaminoacridine, bis(4-aminophenyl)phenylamine, 4,4'-diphenylmethylamine, 4,4'-diphenylamine, 3,6-diaminocarbazole, 9-methyl-3,6-diaminocarbazole, 9-ethyl-3,6-diaminocarbazole, diamines represented by the following formulas (w1) to (w2), and the like.

[0110]

[0111] (Sp represents phenylene, pyrrolidine, piperidine, piperazine, a divalent chain hydrocarbon group having 2 to 20 carbon atoms, or a group in which -CH2- of the divalent chain hydrocarbon group is replaced by a group selected from -O-, -CO-, -CO-O-, -NRCO- (R represents a hydrogen atom or a methyl group), -NRCOO- (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), -COS-, -NR- (R represents a methyl group), pyrrolidine, piperidine, and piperazine.)

[0112] Specific examples of the above formula (12) when Y9 is a divalent organic group having -NH-CO-NH- in the molecule include diamines in the above formula (4) when A1 is -NH-CO-NH-, or a group in which at least one of the -CH2- of a chain hydrocarbon group having 2 to 20 carbon atoms is replaced by -NH-CO-NH-, or a group in which at least one of the -CH2- of a chain hydrocarbon group having 2 to 20 carbon atoms is replaced by -NH-CO-NH- and at least one of the other -CH2- is replaced by a group selected from -O-, -CO-, -CO-O-, -NRCO- (R represents a hydrogen atom or a methyl group), -NRCOO- (R represents a hydrogen atom or a methyl group), -CONR- (R represents a hydrogen atom or a methyl group), -COS-, and -NR- (R represents a methyl group). Specific examples of more preferred diamines include diamines represented by the following formulas (U-1) to (U-9).

[0113]

[0114] Preferred specific examples of the diamines represented by the above formulae (w1) to (w2) include diamines represented by the following formulae (n3-1) to (n3-7) and diamines represented by the following formulae (n4-1) to (n4-6).

[0115]

[0116]

[0117] For the purpose of improving printability, diamine compounds having a carboxyl group (COOH group) or a hydroxyl group (OH group) may also be used. Specifically, 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 or 3,5-diaminobenzoic acid may be mentioned. Among them, 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid or 3,5-diaminobenzoic acid is preferred. In addition, diamine compounds represented by the following formulas [3b-1] to [3b-4] and diamine compounds whose amino groups are secondary amino groups may also be used.

[0118]

[0119] (In formula [3b-1], Q 1represents 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-, m 1 and m 2 Each independently represents an integer from 0 to 4, and m 1 +m 2 represents an integer of 1 to 4, in formula [3b-2], m 3 and m 4 Each independently represents an integer of 1 to 5. In the formula [3b-3], Q 2 represents a straight or branched alkylene group having 1 to 5 carbon atoms, m 5 represents an integer of 1 to 5, in formula [3b-4], Q 3 and Q 4 Each independently represents 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-, m 6 Indicates an integer from 1 to 4. )

[0120] As the diamine component for obtaining the second polyamic acid, diamines used in specific polymers and known diamines can be used in addition to the above, but the present invention is not limited thereto. The diamine component for obtaining the second polyamic acid may be one diamine or two or more diamines may be used in combination.

[0121] The molecular weight of the second polymer contained in the liquid crystal aligning agent of the present invention is not particularly limited as long as a uniform and defect-free coating film can be formed on a substrate, and the preferred weight average molecular weight and number average molecular weight are the same as those of the specific polymer.

[0122] Various additives added to the above-mentioned liquid crystal alignment agent include dielectrics or conductive substances for the purpose of changing the electrical properties of the liquid crystal alignment film, such as the dielectric constant and conductivity; silane coupling agents for the purpose of improving the adhesion between the liquid crystal alignment film and the substrate; cross-linking compounds for the purpose of improving the hardness and density of the film when the liquid crystal alignment film is made; and imidization accelerators for the purpose of efficiently imidizing the polyamic acid when the coating film is fired.

[0123] As the crosslinking compound, it is preferred to add at least one compound selected from the group consisting of crosslinking compounds having a substituent such as an epoxy group, an isocyanate group, an oxetane group, a cyclocarbonate group, a blocked isocyanate group, a hydroxyl group or an alkoxy group, and a crosslinking compound having a polymerizable unsaturated group.

[0124] It should be noted that when there are two or more of these substituents and polymerizable unsaturated bonds in the crosslinking compound, it is preferred from the viewpoint of improving crosslinking. As specific examples of crosslinking compounds, compounds having epoxy or isocyanate groups described in paragraphs

[0169] to

[0190] of International Publication 2011 / 132751; compounds having oxetane groups; amino resins having hydroxyl, alkoxy or lower alkoxyalkyl groups; benzene or phenolic compounds having hydroxyl or alkoxy groups; compounds having cyclic carbonate groups described in paragraphs

[0103] to

[0112] of International Publication 2012 / 014898; compounds having hydroxyalkylamide groups described in International Publication 2015 / 072554; compounds having blocked isocyanate groups described in International Publication 2015 / 141598, etc.

[0125] More preferred specific examples of the crosslinking compound include compounds represented by the following formulae (CL-1) to (CL-13), TAKENATE B-830, and TAKENATE B-882 (all manufactured by Mitsui Chemicals, Inc.).

[0126]

[0127] The content of the crosslinking compound is preferably 0.1 to 100 parts by mass, more preferably 0.1 to 50 parts by mass, further preferably 1 to 50 parts by mass, based on 100 parts by mass of all polymer components contained in the liquid crystal aligning agent, from the viewpoint of improving the orientation of the liquid crystal.

[0128] Examples of the silane coupling agent 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, and N-ethoxycarbonyl-3-aminopropyltrimethoxysilane. 1-Trimethoxysilyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 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-aminopropyltriethoxy Silane, N-phenyl-3-aminopropyl trimethoxysilane, N-phenyl-3-aminopropyl triethoxysilane, N-bis(oxyethylene)-3-aminopropyl trimethoxysilane, N-bis(oxyethylene)-3-aminopropyl triethoxysilane, vinyl trimethoxysilane, vinyl triethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, 3-glycidoxypropyl methyl dimethoxysilane, 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl methyl diethoxysilane, 3- Glycidoxypropyl triethoxysilane, p-styryl trimethoxysilane, 3-methacryloxypropyl methyl dimethoxysilane, 3-methacryloxypropyl trimethoxysilane, 3-methacryloxypropyl methyl diethoxysilane, 3-methacryloxypropyl triethoxysilane, 3-acryloxypropyl trimethoxysilane, trans-(trimethoxysilylpropyl) isocyanurate, 3-mercaptopropyl methyl dimethoxysilane, 3-mercaptopropyl trimethoxysilane, 3-isocyanate propyl triethoxysilane, etc. When using these silane coupling agents, from the viewpoint of guaranteeing liquid crystal orientation, it is preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass, relative to 100 parts by mass of all polymer components contained in the liquid crystal aligning agent.

[0129] The concentration of the polymer containing the specific polymer in the liquid crystal aligning agent of the present invention can be appropriately changed according to the setting of the thickness of the coating film to be formed. Among them, from the perspective of forming a uniform and defect-free coating film, it is preferably 1% by mass or more, and from the perspective of the storage stability of the solution, it is preferably set to 10% by mass or less. The concentration of the particularly preferred polymer is 2 to 8% by mass.

[0130] For the organic solvent contained in the liquid crystal aligning agent of the present invention, as long as the polymer component can be uniformly dissolved, there is no particular limitation. If its specific example is given, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-vinyl-2-pyrrolidone, dimethyl sulfoxide, dimethyl sulfone, γ-butyrolactone, 1,3-dimethyl-imidazolidinone, 3-methoxy-N, N-dimethylpropaneamide, etc. can be given. These can use one or more than two kinds of mixed use. In addition, even if it is a solvent that can not make the polymer component uniformly dissolved alone, as long as the polymer is not precipitated, it can also be mixed into the above-mentioned organic solvent.

[0131] The liquid crystal aligning agent of the present invention may contain a solvent for improving the uniformity of the coating film when the liquid crystal aligning agent is applied to a substrate in addition to the organic solvent for dissolving the polymer component. The solvent generally has a lower surface tension than the organic solvent. Specific examples thereof include ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, butyl cellosolve acetate, dipropylene glycol, 2-(2-ethoxypropoxy)propanol, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, isoamyl lactate, diacetone alcohol, diisobutyl ketone, dipropylene glycol monomethyl ether, diisobutyl carbinol, etc. These solvents may be used in combination of two or more.

[0132] <Method for producing liquid crystal alignment film>

[0133] The method for manufacturing a liquid crystal alignment film using the liquid crystal alignment agent of the present invention is as described above, and is characterized in that the following steps are performed in sequence: a step of applying the liquid crystal alignment agent (step (A)); a step of firing the coating obtained in step (A) (step (B)); a step of irradiating the film obtained in step (B) with polarized ultraviolet rays (step (C)); a step of firing the film obtained in step (C) at a temperature above 100°C and higher than that in step (B) (step (D)).

[0134] <Step (A)>

[0135] As the substrate for coating the liquid crystal aligning agent used in the present invention, as long as it is a substrate with high transparency, there is no particular limitation, and a plastic substrate such as an acrylic substrate, a polycarbonate substrate, etc. can also be used together with a glass substrate, a silicon nitride substrate. At this time, if a substrate with an ITO electrode or the like for driving a liquid crystal is used, it is preferred from the aspect of simplifying the process. In addition, in a reflective liquid crystal display element, if it is a substrate on only one side, an opaque object such as a silicon wafer can also be used, and the electrode in this case can also use a material that reflects light such as aluminum.

[0136] The coating method of the liquid crystal alignment agent is not particularly limited, and is generally performed industrially by screen printing, offset printing, flexographic printing, or inkjet method, etc. Other coating methods include dipping, roll coating, slit coating, spin coating, or spraying, and these methods can be used according to the purpose.

[0137] <Process (B)>

[0138] Step (B) is a step of firing the liquid crystal aligning agent applied to the substrate to form a film. After the liquid crystal aligning agent is applied to the substrate, the solvent can be evaporated or the thermal imidization of the amic acid or amic acid ester in the polymer can be performed by heating means such as a hot plate, a heat circulation oven or an IR (infrared) oven. The drying and firing steps after applying the liquid crystal aligning agent of the present invention can be selected at any temperature and time, and can also be performed multiple times. As the temperature for removing the organic solvent of the liquid crystal aligning agent, it can be carried out in the range of 40 to 150°C, for example. From the viewpoint of shortening the process, it can be carried out at 40 to 120°C. There is no particular limitation on the firing time, and a firing time of 1 to 10 minutes or 1 to 5 minutes can be listed. In the case of thermal imidization of the amic acid or amic acid ester in the polymer, after the step of removing the above-mentioned organic solvent, a firing step can be performed at a temperature range of, for example, 190 to 250°C, or 200 to 240°C. The firing time is not particularly limited, but may be 5 to 40 minutes or 5 to 30 minutes.

[0139] <Process (C)>

[0140] Step (C) is a step of irradiating the film obtained in step (B) with polarized ultraviolet rays. As ultraviolet rays, ultraviolet rays with a wavelength of 200 to 400 nm are preferably used, and ultraviolet rays with a wavelength of 200 to 300 nm are more preferably used. In order to improve the orientation of the liquid crystal, the substrate coated with the liquid crystal orientation film can be heated at 50 to 250°C while irradiating with ultraviolet rays. In addition, the irradiation amount of the above-mentioned radiation is preferably 1 to 10,000 mJ / cm 2 Among them, 100 to 5,000 mJ / cm is preferred. 2The liquid crystal alignment film produced in this way can stably align the liquid crystal molecules in a certain direction.

[0141] The higher the extinction ratio of polarized ultraviolet light is, the higher anisotropy can be imparted, which is preferred. Specifically, the extinction ratio of linearly polarized ultraviolet light is preferably 10:1 or more, more preferably 20:1 or more.

[0142] <Process (D)>

[0143] Step (D) is a step of calcining the film obtained in step (C) at a temperature of 100°C or higher and higher than that in step (B). The calcination temperature is not particularly limited as long as it is 100°C or higher and higher than the calcination temperature in step (B), but is preferably 150 to 300°C, more preferably 150 to 250°C, and further preferably 200 to 250°C. The calcination time is preferably 5 to 120 minutes, more preferably 5 to 60 minutes, and further preferably 5 to 30 minutes.

[0144] Since the reliability of a liquid crystal display element may fall when the thickness of the liquid crystal aligning film after baking is too thin, it is preferably 5-300 nm, and more preferably 10-200 nm.

[0145] Furthermore, after performing any of the above-mentioned steps (C) and (D), the obtained liquid crystal aligning film may be subjected to contact treatment with water or a solvent.

[0146] As the solvent used in the above-mentioned contact treatment, as long as it is a solvent that dissolves the decomposed product generated by the liquid crystal alignment film by the irradiation of ultraviolet rays, it is not particularly limited. As a specific example, 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, 3-methoxy methyl propionate, 3-ethoxy ethyl propionate, propyl acetate, butyl acetate or cyclohexyl acetate etc. can be listed. Among them, from the aspect of versatility and the safety of the solvent, preferably water, 2-propanol, 1-methoxy-2-propanol or ethyl lactate. More preferably water, 1-methoxy-2-propanol or ethyl lactate. The solvent can be 1 kind, or 2 or more kinds can be combined.

[0147] As the above-mentioned contact treatment, that is, the liquid crystal alignment film irradiated with polarized ultraviolet rays is contacted with water or a solvent, immersion treatment and spray treatment (also called spray treatment) can be listed. The treatment time of these treatments is preferably 10 seconds to 1 hour from the aspect of effectively dissolving the decomposition products generated by the liquid crystal alignment film due to ultraviolet rays. Among them, it is preferred to perform an immersion treatment for 1 minute to 30 minutes. In addition, the solvent during the above-mentioned contact treatment can be at room temperature or heated, preferably 10 to 80°C. Among them, 20 to 50°C is preferred. Moreover, from the aspect of the solubility of the decomposition product, ultrasonic treatment, etc. can be performed as needed.

[0148] After the above-mentioned contact treatment, it is preferred to perform rinsing (also referred to as washing) with a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone or methyl ethyl ketone, and calcining of the liquid crystal alignment film. At this time, either rinsing or calcining can be performed, or both can be performed. The calcining temperature is preferably 150 to 300°C. Among them, 180 to 250°C is preferred. More preferably, 200 to 230°C. In addition, the calcining time is preferably 10 seconds to 30 minutes. Among them, 1 to 10 minutes is preferred.

[0149] The liquid crystal alignment film of the present invention is suitable as a liquid crystal alignment film of a liquid crystal display element of a transverse electric field mode such as an IPS mode and an FFS mode, and is particularly useful as a liquid crystal alignment film of a liquid crystal display element of an FFS mode. The liquid crystal display element is obtained as follows: after obtaining a substrate with a liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention, a liquid crystal cell is prepared by a known method, and the liquid crystal cell is used to obtain the liquid crystal display element.

[0150] As an example of a method for making a liquid crystal unit, a liquid crystal display element with a passive matrix structure is used as an example. It should be noted that a liquid crystal display element with an active matrix structure in which a switching element such as a TFT (Thin Film Transistor) is provided in each pixel portion constituting the image display may also be used.

[0151] Specifically, transparent glass substrates are prepared, a common electrode is provided on one substrate, and segment electrodes are provided on the other substrate. These electrodes can be, for example, ITO electrodes, and patterned so as to achieve the desired image representation. Next, an insulating film is provided on each substrate in a manner covering the common electrode and the segment electrodes. The insulating film can be, for example, a SiO2-TiO2 film formed by a sol-gel method.

[0152] Next, a liquid crystal alignment film is formed on each substrate, and another substrate is overlapped on one substrate in a manner that the liquid crystal alignment film surfaces are opposite to each other, and the periphery is bonded with a sealant. In order to control the substrate gap, spacers are usually pre-mixed in the sealant. In addition, it is preferred that spacers for controlling the substrate gap are also pre-spread in the surface portion where the sealant is not provided. An opening that can be filled with liquid crystal from the outside is pre-set in a part of the sealant. Next, a liquid crystal material is injected into the space surrounded by two substrates and the sealant through the opening provided in the sealant, and then the opening is sealed with an adhesive. The injection can use a vacuum injection method or a method using capillary phenomena in the atmosphere. The liquid crystal material can use any of a positive liquid crystal material and a negative liquid crystal material. Next, a polarizing plate is set. Specifically, a pair of polarizing plates are attached to the opposite side of the two substrates to the liquid crystal layer.

[0153] By operating as described above and using the manufacturing method of the present invention, the following liquid crystal alignment film can be obtained: a liquid crystal alignment film that can suppress the afterimage caused by long-term AC driving in the liquid crystal display elements of the IPS driving method and the FFS driving method, does not have the adverse conditions such as bright spots caused by the residual low molecular weight compounds, and can be manufactured through fewer steps than before.

[0154] Example

[0155] 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 following compounds and the methods for measuring the properties are as follows.

[0156] (Diamine)

[0157]

[0158] (Boc represents tert-butoxycarbonyl.)

[0159] (Tetracarboxylic dianhydride)

[0160] CA-X-1: A compound represented by the following formula (CA-X-1)

[0161]

[0162] (Compound C)

[0163] c-1: Compound represented by the following formula (c-1)

[0164] (Other additives)

[0165] LS-4668: 3-Glycidoxypropyltriethoxysilane (the compound shown in (s-1) below)

[0166]

[0167] (Organic Solvent)

[0168] NMP: N-methyl-2-pyrrolidone, GBL: γ-butyrolactone,

[0169] BCS: Butyl Cellosolve,

[0170] <Determination of Imidization Ratio>

[0171] 20 mg of polyimide powder was placed in an NMR sample tube (NMR sampling tube standard, (manufactured by Kusano Scientific Co., Ltd.), add 0.53 ml of deuterated dimethyl sulfoxide (DMSO-d6, 0.05% TMS (tetramethylsilane) mixed product), and apply ultrasonic waves to completely dissolve it. The solution was measured with a 500 MHz proton NMR using an NMR measuring instrument (JNW-ECA500, manufactured by JEOL DATUM LTD.). For the imidization rate, the proton derived from the structure that does not change before and after the imidization is determined as a reference proton, and the peak cumulative value of the proton derived from the NH group of the amic acid appearing around 9.5 ppm to 10.0 ppm is used to calculate it by the following formula.

[0172] Imidization rate (%) = (1-α·x / y) × 100

[0173] In the above formula, x is the peak cumulative value of protons derived from the NH group of the amic acid, y is the peak cumulative value of the reference proton, and α is the number ratio of the reference proton to one NH group proton of the amic acid in the case of polyamic acid (imidation ratio 0%).

[0174] [Synthesis of polymer]

[0175] <Synthesis example 1>

[0176] In a four-necked flask with a stirring device and a nitrogen inlet tube, 3.62 g (14.8 mmol) of DA-h-1, 4.75 g (14.8 mmol) of DA-h-2, 1.92 g (17.8 mmol) of DA-i-1, and 4.05 g (11.9 mmol) of DA-j-1 were weighed, and NMP was added so that the solid content concentration became 12% by mass, and stirred while nitrogen was sent to dissolve. While stirring the obtained solution, 10.1 g (45.2 mmol) of CA-1-1, 2.12 g (8.5 mmol) of CA-2-1, and 0.83 g (2.8 mmol) of CA-3-1 were added, and NMP was further added so that the solid content concentration became 15% by mass. Then, stirring was performed at 40°C for 24 hours to obtain a polyamic acid solution.

[0177] Take 30.0g of the above-mentioned polyamic acid solution obtained in a 100mL four-necked flask with a stirring device and a nitrogen inlet tube, add NMP in a way that the solid content concentration becomes 10% by mass, and stir for 30 minutes. Add acetic anhydride 2.80g and pyridine 1.50g to the obtained polyamic acid solution, heat at 55°C for 3 hours, and carry out chemical imidization. The obtained reaction solution is put into 3.5 times the amount of methanol of the reaction solution mass while stirring, filter out the precipitate, and then wash it with methanol 3 times. The obtained resin powder is dried at 60°C for 12 hours to obtain a powder of polyimide (PI-A-1). The imidization rate of the polyimide resin powder is 62%. NMP is added to the obtained polyimide (PI-A-1), and stirred at 70°C for 24 hours to obtain a solution of polyimide (PI-A-1) having a solid content concentration of 12% by mass.

[0178] <Synthesis Examples 2 to 5>

[0179] Using the diamine component, tetracarboxylic acid component and organic solvent shown in Table 1 below, the same procedures as in Synthesis Example 1 were carried out to obtain solutions of polyimides (PI-A-2) to (PI-A-4), (R-PI-1) and polyamic acids (PAA-B-1) to (PAA-B-3) shown in Table 1 below. LS-4668 was added to polyamic acids (PAA-B-1) to (PAA-B-3) to give 1% by mass relative to the solid content of the polyamic acid.

[0180] In Table 1, the numerical values ​​in brackets show the blending ratio (mol parts) of each compound relative to 100 mol parts of the total amount of the tetracarboxylic acid components used in the synthesis for the tetracarboxylic acid components, and the blending ratio (mol parts) of each compound relative to 100 mol parts of the total amount of the diamine components used in the synthesis for the diamine acid components. For the organic solvent, the blending ratio (mass parts) of each organic solvent relative to 100 parts by mass of the total amount of the organic solvent used in the synthesis is shown.

[0181] [Table 1]

[0182]

[0183] [Preparation of Liquid Crystal Alignment Agent]

[0184] <Example 1>

[0185] The solution of polyimide (PI-A-1) obtained in Synthesis Example 1 was diluted with NMP and BCS and stirred at room temperature. Then, the obtained solution was filtered with a filter having a pore size of 0.5 μm, thereby obtaining a liquid crystal aligning agent (1) having a solvent composition ratio of (NMP:BCS=80:20 (mass ratio)) and a polymer solid content concentration of 6 mass % (see Table 2 below). No abnormalities such as turbidity and precipitation were observed in the liquid crystal aligning agent, and it was confirmed to be a uniform solution.

[0186] <Examples 2 to 4, Comparative Example 1>

[0187] Liquid crystal aligning agents (2) to (4) and (R1) were obtained in the same manner as in Example 1, except that each polymer shown in Table 2 below was used.

[0188] <Examples 5 to 7, Comparative Example 2>

[0189] The solution of the polyimide (PI-A-2) obtained in Synthesis Example 2 or the polyimide (R-PI-1) obtained in Synthesis Example 5, and the solution of the polyamic acid (PAA-B-1) to (PAA-B-3) obtained in Synthesis Examples 6 to 8 were diluted with NMP, GBL and BCS, and then compound (c-1) was added in an amount of 3 parts by mass relative to 100 parts by mass of the total polymer, and stirred at room temperature. Next, the obtained solution was filtered with a filter having a pore size of 0.5 μm, thereby obtaining a polymer component ratio of polyimide: polyamic acid = 40:60 (solid content conversion mass ratio), a solvent composition ratio of NMP: GBL: BCS = 50:30:20 (mass ratio), and a polymer solid content concentration of 6% by mass of liquid crystal aligning agents (5) to (7) and (R2) (see Table 2 below). No abnormalities such as turbidity and precipitation were observed in the liquid crystal aligning agent, and it was confirmed to be a uniform solution.

[0190] In Table 2, the values ​​in brackets show the mixing ratio (mass parts) of each polymer component or compound (C) to a total of 100 parts by mass of the polymer component used in the preparation of the liquid crystal aligning agent for the polymer and compound (C). For the organic solvent, the mixing ratio (mass parts) of each organic solvent to a total of 100 parts by mass of the organic solvent used in the preparation of the liquid crystal aligning agent is shown.

[0191] [Table 2]

[0192]

[0193] [Production of Liquid Crystal Display Element]

[0194] A liquid crystal cell having a configuration of an FFS mode liquid crystal display element was produced.

[0195] First, prepare a substrate with electrodes. The substrate is a glass substrate with a size of 30mm×50mm and a thickness of 0.7mm. An ITO electrode with a solid pattern is formed on the substrate as the first layer constituting the counter electrode. A SiN (silicon nitride) film formed by a CVD method is formed as the second layer on the counter electrode of the first layer. The film thickness of the SiN film of the second layer is 500nm, and it functions 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 is arranged to form two pixels, the first pixel and the second pixel. The size of each pixel is 10mm in the vertical direction and about 5mm in the horizontal direction. At this time, the counter electrode of the first layer and the pixel electrode of the third layer are electrically insulated by the action of the SiN film of the second layer.

[0196] The pixel electrode of the third layer has a comb-like shape formed by arranging a plurality of electrode elements whose central portion is bent into a "く" shape with an internal angle of 160°. The width of each electrode element in the short side direction is 3μm, and the interval between the electrode elements is 6μm. The pixel electrode forming each pixel is composed of a plurality of electrode elements whose central portion is bent into a "く" shape, so the shape of each pixel is not a rectangle, but has a thick "く"-like shape bent in the central portion like the electrode elements. Moreover, each pixel is divided into upper and lower parts with the bent portion in the center as the boundary, and has a first area on the upper side of the bent portion and a second area on the lower side.

[0197] Next, a liquid crystal alignment agent was applied by spin coating on the above-mentioned substrate with electrodes and a glass substrate with a columnar spacer having a height of 4 μm and an ITO film formed on the back. After drying on a hot plate at 80°C for 2 minutes, the coating surface was irradiated with ultraviolet rays with a wavelength of 254 nm and an extinction ratio of 26:1 through a polarizing plate, and then calcined in a hot peak circulation oven at 230°C for 30 minutes to obtain a substrate with a liquid crystal alignment film having a film thickness of 100 nm. It should be noted that the liquid crystal alignment film formed on the above-mentioned substrate with electrodes is oriented in a manner that the direction of bisecting the inner angle of the pixel bending portion is orthogonal to the orientation direction of the liquid crystal, and the liquid crystal alignment film formed on the second glass substrate is oriented in a manner that the orientation direction of the liquid crystal on the first substrate is consistent with the orientation direction of the liquid crystal on the second substrate when the liquid crystal unit is manufactured. The two substrates with liquid crystal alignment films obtained are set as a group, and a sealant is printed on the substrate in the form of a liquid crystal injection port, and the other substrate is bonded in a manner that the liquid crystal alignment film faces face to face. Thereafter, the sealant was cured to produce an empty cell with a cell gap of 4 μm. Liquid crystal MLC-3019 (Merck) was injected into the empty cell by a reduced pressure injection method, and the injection port was sealed to obtain a FFS liquid crystal display element. Thereafter, the obtained liquid crystal display element was heated at 120° C. for 1 hour, and left at 23° C. overnight for evaluation.

[0198] [evaluate]

[0199] · Evaluation of radiation dose margin

[0200] The liquid crystal display element obtained above was applied with an AC voltage of ±5 V at a frequency of 60 Hz for 120 hours in a constant temperature environment of 60° C. Thereafter, the pixel electrode and the counter electrode of the liquid crystal display element were short-circuited and left at room temperature for one day.

[0201] For the liquid crystal display element subjected to the above-mentioned treatment, the deviation between the alignment direction of the liquid crystal in the first region of the pixel and the alignment direction of the liquid crystal in the second region in the no-voltage-applied state was calculated as an angle.

[0202] Specifically, a liquid crystal display element is set between two polarizing plates arranged in a manner such that the polarization axes are orthogonal, the backlight is turned on, and the arrangement angle of the liquid crystal unit is adjusted so that the intensity of the transmitted light in the first area of ​​the pixel is minimized. Then, the rotation angle (hereinafter referred to as Δ ac ).

[0203] Use this Δ ac Minimum light exposure E less than 0.15° min (mJ / cm 2 ) and the highest light exposure E max(mJ / cm 2 ), and evaluated according to the following three-level index. The evaluation results are shown in the following Table 3.

[0204] Excellent: E max With E min The difference is 300mJ / cm 2 above.

[0205] Good: E max With E min The difference is 200mJ / cm 2 Above and less than 300mJ / cm 2 .

[0206] Bad: E max With E min The difference is less than 200mJ / cm 2 .

[0207] [Table 3]

[0208]

[0209] As described above, the liquid crystal alignment films obtained from the liquid crystal alignment agents (1) to (7) used in Examples 1 to 7 of the present invention were irradiated with 150 to 350 mJ / cm 2 , or 150~450mJ / cm 2 When the light exposure is ac The liquid crystal alignment agents (R1) and (R2) used in Comparative Examples 1 and 2 were irradiated with 150 to 250 mJ / cm 2 When the light exposure is Δ ac Less than 0.15°, showing good afterimage characteristics, but under irradiation of 350mJ / cm 2 When the light exposure is Δ ac If the angle is above 0.15°, good afterimage characteristics cannot be obtained. Based on the above, it can be seen that the light irradiation margin can be expanded by the liquid crystal alignment agent of the present invention, and a liquid crystal alignment film with good afterimage characteristics can be obtained. Therefore, the liquid crystal alignment film obtained by the liquid crystal alignment agent of the present invention has a high yield in the manufacture of liquid crystal panels, and can reduce the afterimage caused by the AC drive generated in the liquid crystal display elements of the IPS drive mode and the FFS drive mode, and can obtain the IPS drive mode and the FFS drive mode liquid crystal display elements with excellent afterimage characteristics.

[0210] Industrial Applicability

[0211] The liquid crystal aligning agent of this invention is useful for formation of the liquid crystal aligning film of the wide range of liquid crystal display elements, such as an IPS drive system and an FFS drive system.

[0212] It should be noted that the entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2018-216789 filed on November 19, 2018 are cited herein and incorporated as a disclosure of the specification of the present invention.

Claims

1. A liquid crystal alignment agent, characterized in that: The invention relates to a polyimide, wherein the polyimide is an imide of a polyimide precursor obtained by a polymerization reaction of a tetracarboxylic acid component and a diamine component, wherein the tetracarboxylic acid component comprises: a tetracarboxylic dianhydride represented by the following formula (1) or a derivative thereof, a tetracarboxylic dianhydride represented by the following formula (2) or a derivative thereof, and an aromatic tetracarboxylic dianhydride represented by the following formula (6), X1 is a structure represented by any one of the following formulae (X1-12) to (X1-16), X2 is a structure represented by the following formulae (X2-1) or (X2-2), and X3 is an aromatic ring having four connecting bonds. The content ratio of the tetracarboxylic dianhydride or its derivative represented by formula (1) is 50 to 98 mol% relative to the tetracarboxylic acid component reacted with the diamine component; The tetracarboxylic acid component contains 1 to 30 mol % of the tetracarboxylic dianhydride or a derivative thereof represented by the formula (2) based on the tetracarboxylic acid component; The tetracarboxylic acid component contains 1 to 20 mol % of the tetracarboxylic dianhydride or a derivative thereof represented by the formula (6) based on the tetracarboxylic acid component; The diamine component contains at least one diamine selected from the group consisting of diamines represented by any of the following formulas (3), (4), and (5). A1 and A4 each independently represent a single bond, -CO-O-, -OCO-, -NRCO-, -NRCOO-, -CONR-, -COS-, -NR1-CO-NR2-, a divalent chain hydrocarbon group having 2 to 20 carbon atoms, or a group in which -CH2- of the divalent chain hydrocarbon group is replaced by a group selected from -O-, -CO-, -CO-O-, -NRCO-, -NRCOO-, -CONR-, -COS-, -NR1-CO-NR2-, -NR-, pyrrolidine, piperidine, and piperazine ( h1), wherein in the -NRCO-, R represents a hydrogen atom or a methyl group, in the -NRCOO-, R represents a hydrogen atom or a methyl group, in the -CONR-, R represents a hydrogen atom or a methyl group, in the -NR1-CO-NR2-, R1 and R2 each independently represent a hydrogen atom or a methyl group, and in the -NR-, R represents a methyl group; A2 is a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a mercapto group, a nitro group, a phosphoric acid group, or a monovalent organic group having 1 to 20 carbon atoms; wherein the chain hydrocarbon groups of A1 and A4 and the group (h1) have Some of the hydrogen atoms may be partially or entirely substituted by an alkyl group having 1 to 3 carbon atoms or a halogen atom; A3 is a divalent chain hydrocarbon group having 1 to 20 carbon atoms, or a group (h2) in which -CH2- of the divalent chain hydrocarbon group is replaced by a group selected from -O-, -CO-, -CO-O-, -NRCO-, -NRCOO-, -CONR-, -COS-, -NR1-CO-NR2-, -NR-, pyrrolidine, piperidine, and piperazine, wherein in the -NRCO-, R represents a hydrogen atom or a methyl group, and the -NRCOO -, R represents a hydrogen atom or a methyl group, in the -CONR-, R represents a hydrogen atom or a methyl group, in the -NR1-CO-NR2-, R1 and R2 each independently represent a hydrogen atom or a methyl group, and in the -NR-, R represents a methyl group; wherein a part or all of the hydrogen atoms possessed by the chain hydrocarbon group of A3 and the group (h2) are optionally substituted by an alkyl group having 1 to 3 carbon atoms or a halogen atom; a is an integer of 1 to 4, and when a is greater than 2, A2 is optionally the same or different; b and c are each independently an integer of 1 or 2; d is an integer of 0 or 1; When the diamine represented by the formula (3) is present, the content of the diamine represented by the formula (3) is 30 mol% or 50 to 100 mol% relative to 1 mol of the diamine component; When the diamine represented by the formula (4) or (5) is present, the content of the diamine represented by the formula (4) or (5) is 25 mol% or 50 to 100 mol% based on 1 mol of the diamine component.

2. The liquid crystal alignment agent according to claim 1, wherein The imidization rate of the polyimide is 10 to 100%.

3. The liquid crystal aligning agent according to claim 1 or 2, wherein: In the formula (2), X2 is the structure represented by the formula (X2-1).

4. The liquid crystal alignment agent according to claim 1, wherein The diamine component contains at least one diamine selected from the group consisting of diamines having a structure represented by the following formula (4), A1 represents a single bond, -CO-O-, -OCO-, -NRCO-, -NRCOO-, -CONR-, -COS-, -NR1-CO-NR2-, a divalent chain hydrocarbon group having 2 to 20 carbon atoms, or a group (h1) in which -CH2- of the divalent chain hydrocarbon group is replaced by a group selected from -O-, -CO-, -CO-O-, -NRCO-, -NRCOO-, -CONR-, -COS-, -NR1-CO-NR2-, -NR-, pyrrolidine, piperidine, and piperazine, wherein the -NR In CO-, R represents a hydrogen atom or a methyl group, in -NRCOO-, R represents a hydrogen atom or a methyl group, in -CONR-, R represents a hydrogen atom or a methyl group, in -NR1-CO-NR2-, R1 and R2 each independently represent a hydrogen atom or a methyl group, and in -NR-, R represents a methyl group; A2 is a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a mercapto group, a nitro group, a phosphate group, or a monovalent organic group having 1 carbon number; a is an integer of 1 to 4, and when a is greater than 2, A2 may be the same or different; b and c each independently represent an integer of 1 or 2.

5. The liquid crystal alignment agent according to claim 1, wherein The diamine component contains at least one diamine selected from the group consisting of diamines having a structure represented by the following formula (4), A1 represents a single bond, -CO-O-, -OCO-, -NRCO-, -NRCOO-, -CONR-, -COS-, -NR1-CO-NR2-, a divalent chain hydrocarbon group having 2 to 20 carbon atoms, or a group (h1) in which -CH2- of the divalent chain hydrocarbon group is replaced by a group selected from -O-, -CO-, -CO-O-, -NRCO-, -NRCOO-, -CONR-, -COS-, -NR1-CO-NR2-, and -NR-, wherein in the -NRCO-, R represents a hydrogen atom or a methyl group. In the -NRCOO-, R represents a hydrogen atom or a methyl group. In the -CONR-, R represents a hydrogen atom or a methyl group. In the -NR1-CO-NR2-, R1 and R2 each independently represent a hydrogen atom or a methyl group. In the -NR-, R represents a methyl group. A2 is a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a mercapto group, a nitro group, a phosphate group, or a monovalent organic group having 1 carbon number. a is an integer of 1 to 4. When a is 2 or more, A2 may be the same or different. b and c each independently represent an integer of 1 or 2.

6. The liquid crystal aligning agent according to claim 1 or 2, wherein: The diamine component contains at least one diamine selected from the group consisting of the following formulas (DA-3-1), (DA-4-1) to (DA-4-24), and (DA-5-1) to (DA-5-3), 7. The liquid crystal aligning agent according to claim 1 or 2, wherein: It also contains polyamic acid.

8. The liquid crystal alignment agent according to claim 7, wherein: As the diamine component for obtaining the polyamic acid, a diamine represented by the following formula (12) is used: Y9 represents a divalent organic group having a tertiary nitrogen atom, or a divalent organic group having -NH-CO-NH- in the molecule, and A9 each independently represents a hydrogen atom, or an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkynyl group having 2 to 5 carbon atoms.

9. A method for producing a liquid crystal alignment film, comprising the steps of (A), (B), (C), and (D), Step (A): a step of applying the liquid crystal aligning agent according to any one of claims 1 to 8; Step (B): a step of firing the coating film obtained in step (A); Step (C): a step of irradiating the film obtained in step (B) with polarized ultraviolet rays; Step (D): A step of calcining the film obtained in step (C) at a temperature of 100° C. or higher and higher than that in step (B).

10. The method for manufacturing a liquid crystal alignment film according to claim 9, wherein: In the step (B), calcination is performed at 50°C to 150°C.

11. The method for producing a liquid crystal alignment film according to claim 9 or 10, wherein: In the step (D), the film is fired at 150 to 300°C. 12 . A liquid crystal aligning film obtained using the liquid crystal aligning agent according to claim 1 . 13 . A liquid crystal display element comprising the liquid crystal aligning film according to claim 12 . The liquid crystal display element according to claim 13 , wherein the liquid crystal is driven by a transverse electric field.

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