Liquid crystal alignment agent for photo-alignment method, liquid crystal alignment film and liquid crystal display element

Abstract

The invention relates to a liquid crystal alignment agent for a photo-alignment method, a liquid crystal alignment film and a liquid crystal display element. The invention relates to a liquid crystal alignment agent for a photo-alignment method, a liquid crystal alignment film formed by the liquid crystal alignment agent for the photo-alignment method and a liquid crystal display element comprising the liquid crystal alignment film, wherein the liquid crystal alignment agent for the photo-alignment method is not easy to flicker after being driven at a high voltage. The liquid crystal alignment agent for the photo-alignment method comprises a polymer component (A) and a solvent (B), wherein the polymer component (A) comprises a first polymer (A1) and a second polymer (A2). The second polymer (A2) is selected from at least one of a group consisting of a polyimide precursor and an imidized polymer formed by the polyimide precursor, the polyimide precursor of the second polymer (A2) comprises a structure represented by a formula (II), and the definitions of V1, V2, V3 and W1 in the formula (II) are respectively as described in the description and the claims. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film and a liquid crystal display element, and in particular to a liquid crystal alignment agent for a photo-alignment method that is less likely to flicker after high-voltage driving, a liquid crystal alignment film formed by the liquid crystal alignment agent for the photo-alignment method, and a liquid crystal display element comprising the liquid crystal alignment film. Background Art

[0002] In recent years, LCDs have become increasingly popular in applications requiring high resolution and fast response times, such as medical equipment, aerospace, image processing, and industrial control. LCDs used in these applications must be able to quickly and accurately display high-resolution images and data, while also being able to withstand extreme environmental conditions. Driving LCDs with high voltages allows them to achieve higher pixel densities and faster refresh rates, meeting the demands of these specialized applications.

[0003] Based on the driving mechanism of liquid crystal molecules, liquid crystal displays (LCDs) currently are categorized as those driven by longitudinal electric fields and those driven by transverse electric fields. Examples of LCDs driven by longitudinal electric fields include twisted nematic (TN) LCDs and vertical alignment (VA) LCDs. Examples of LCDs driven by transverse electric fields include in-plane switching (IPS) LCDs and fringe field switching (FFS) LCDs.

[0004] In the above-mentioned liquid crystal displays, the alignment treatment method currently used is a friction method, which is used to make the liquid crystal alignment film have grooves that can align the liquid crystal molecules along a certain direction. The most popular alignment treatment method in the industry is to rub the liquid crystal alignment film formed by polyimide polymers obtained by imidization of polyamic acid polymers and / or polyamic acid polymers with cotton cloth, nylon cloth or polyester cloth in one direction. The alignment treatment method using friction is a simple, highly productive and industrially useful method. However, with the improvement of performance requirements for liquid crystal displays, the refinement of image quality and the increase in size, in order to avoid various problems such as damage to the liquid crystal alignment film caused by dust and static electricity generated by friction treatment and alignment unevenness, a photo-alignment method has emerged to give the liquid crystal alignment film a photo-alignment ability by irradiating it with polarized radiation, such as the photo-alignment method disclosed in Japanese Patent Laid-Open No. H09297313.

[0005] However, although the liquid crystal alignment film obtained by the optical alignment method can avoid the problems caused by the alignment treatment method using the friction method, the liquid crystal display using the liquid crystal alignment film obtained by the optical alignment method currently has the problem of excessive flicker after being driven by high voltage, which makes it unable to meet application requirements. Summary of the Invention

[0006] The first object of the present invention is to provide a liquid crystal alignment agent for use in a photo-alignment method.

[0007] The liquid crystal alignment agent used in the photo-alignment method of the present invention comprises a polymer component (A) and a solvent (B).

[0008] The polymer component (A) includes a first polymer (A1) and a second polymer (A2), wherein the first polymer (A1) is selected from at least one of the group consisting of a polyimide precursor and an imidized polymer formed from the polyimide precursor, and the second polymer (A2) is selected from at least one of the group consisting of a polyimide precursor and an imidized polymer formed from the polyimide precursor.

[0009] The polyimide precursor of the first polymer (A1) comprises a structure represented by formula (I),

[0010]

[0011] X 1 represents at least one of the structures represented by formula (I-1) to formula (I-7), "*" represents the bonding position,

[0012]

[0013]

[0014] X 11 、X 12 、X 13 and X 14 each independently represents hydrogen, halogen, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms and containing fluorine, or a phenyl group,

[0015] X 15 With X 16 Each independently represents hydrogen or methyl,

[0016] X 2 represents hydrogen or an alkyl group having 1 to 4 carbon atoms,

[0017] X 3 represents hydrogen or an alkyl group having 1 to 4 carbon atoms,

[0018] Y1 represents a divalent organic group.

[0019] The polyimide precursor of the second polymer (A2) comprises a structure represented by formula (II),

[0020]

[0021] V 1 Represents the structure shown in formula (II-1), "*" represents the bonding position,

[0022]

[0023] V 2 represents hydrogen or an alkyl group having 1 to 4 carbon atoms,

[0024] V 3 represents hydrogen or an alkyl group having 1 to 4 carbon atoms,

[0025] W 1 The structure represented by formula (II-2) is represented by

[0026]

[0027] In the formula (II-2), R 1 to R 10 At least two of them are “*” representing bonding positions, and the rest are H or monovalent organic groups.

[0028] In the liquid crystal alignment agent used in the optical alignment method of the present invention, the X 1 The structure represented by formula (I-1) is selected from the structures represented by formula (I-1-1) to formula (I-1-6),

[0029]

[0030] In the liquid crystal alignment agent used in the photo-alignment method of the present invention, the X 1 The structure represented by formula (I-1) is the structure represented by formula (I-1-1),

[0031]

[0032] In the liquid crystal alignment agent for the photo-alignment method of the present invention, the polyimide precursor of the second polymer (A2) is formed by reacting a reaction composition comprising a tetracarboxylic dianhydride component (a2) and a diamine component (b2), and the tetracarboxylic dianhydride component (a2) comprises V in the structure represented by the formula (II). 1 The diamine component (b2) comprises W in the structure shown in the formula (II) 1 .

[0033] A second object of the present invention is to provide a liquid crystal alignment film.

[0034] The liquid crystal alignment film of the present invention is formed by the liquid crystal alignment agent used in the photo-alignment method as described above.

[0035] A third object of the present invention is to provide a liquid crystal display element.

[0036] The liquid crystal display element of the present invention comprises the liquid crystal alignment film described above.

[0037] The beneficial effect of the present invention is that: by using the second polymer (A2) prepared by the polyimide precursor containing the structure represented by formula (II), the liquid crystal alignment film formed by the liquid crystal alignment agent used in the photoalignment method can give the liquid crystal display element a low flicker after high-voltage driving, so the liquid crystal display element is not easy to flicker after being driven by high voltage. DETAILED DESCRIPTION

[0038] The present invention provides a liquid crystal alignment agent for photo-alignment method, comprising: a polymer component (A) and a solvent (B). The polymer component (A) comprises a first polymer (A1) and a second polymer (A2).

[0039] Polymer component (A)

[0040] <First polymer (A1)>

[0041] The first polymer (A1) is at least one selected from the group consisting of a polyimide precursor and an imidized polymer formed from the polyimide precursor. The polyimide precursor of the first polymer (A1) comprises a structure represented by formula (I).

[0042]

[0043] In the formula (I), X 1 represents at least one of the structures represented by formula (I-1) to formula (I-7), "*" represents the bonding position, X 2 represents hydrogen or an alkyl group having 1 to 4 carbon atoms, X 3 represents hydrogen or an alkyl group having 1 to 4 carbon atoms, Y 1 represents a divalent organic group.

[0044]

[0045] In the formula (I-1), X 11 、X 12 、X 13 and X 14Each independently represents hydrogen, halogen, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms and containing fluorine, or a phenyl group.

[0046] In the formula (I-7), X 15 With X 16 Each independently represents hydrogen or methyl.

[0047] In some embodiments of the present invention, the X 1 The structure represented by formula (I-1) is selected from the structures represented by formula (I-1-1) to formula (I-1-6).

[0048]

[0049] In some embodiments of the present invention, the X 1 The structure represented by formula (I-1) is the structure represented by formula (I-1-1).

[0050]

[0051] In some embodiments of the present invention, the first polymer (A1) is at least one selected from the group consisting of a polyimide precursor obtained by reacting a tetracarboxylic dianhydride component (a1) and a diamine component (b1), and an imidized polymer formed from the polyimide precursor.

[0052] [Tetracarboxylic dianhydride component (a1)]

[0053] [Alicyclic tetracarboxylic dianhydride compound (a1-1)]

[0054] In some embodiments of the present invention, the tetracarboxylic dianhydride component (a1) comprises an alicyclic tetracarboxylic dianhydride compound (a1-1) represented by formula (A11) or a derivative thereof.

[0055]

[0056] The alicyclic tetracarboxylic dianhydride compound (a1-1) or its derivative represented by the formula (A11) may be composed of a single tetracarboxylic dianhydride or its derivative, or may be composed of a plurality of tetracarboxylic dianhydrides or their derivatives. The alicyclic tetracarboxylic dianhydride compound (a1-1) represented by the formula (A11) is, for example, an acid dianhydride obtained by intramolecular dehydration of four carboxyl groups including at least one carboxyl group bonded to an alicyclic structure. However, none of the four carboxyl groups are bonded to an aromatic ring. Alternatively, it is not necessary to be composed only of an alicyclic structure, and a portion thereof may also have a chain hydrocarbon structure or an aromatic ring structure. The aromatic tetracarboxylic dianhydride is, for example, an acid dianhydride obtained by intramolecular dehydration of four carboxyl groups including at least one carboxyl group bonded to an aromatic ring. However, the aromatic tetracarboxylic dianhydride is not necessary to be composed only of an aromatic ring structure, and a portion thereof may also have a chain hydrocarbon structure or an alicyclic structure. The non-cyclic aliphatic tetracarboxylic dianhydride may be, for example, an acid dianhydride obtained by intramolecular dehydration of four carboxyl groups bonded to a chain hydrocarbon structure. However, the non-cyclic aliphatic tetracarboxylic dianhydride does not need to be composed of only a chain hydrocarbon structure, and a portion thereof may have an alicyclic structure or an aromatic ring structure.

[0057] In the formula (A11), X 1 At least one selected from the group consisting of the structures represented by Formula (I-1) to Formula (I-7), wherein "*" represents a bonding position.

[0058]

[0059] In the formula (I-1), X 11 、X 12 、X 13 With X 14 Each independently represents hydrogen, halogen, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms and containing a fluorine atom, or a phenyl group. 15 With X 16 Each independently represents hydrogen or methyl.

[0060] In some embodiments of the present invention, in the formula (A11), the X 1 The structure represented by formula (I-1) is selected from the structures represented by formulas (I-1-1) to (I-1-6).

[0061]

[0062] In some embodiments of the present invention, preferably, the X 1 The structure represented by formula (I-1) is the structure represented by formula (I-1-1).

[0063] In some embodiments of the present invention, based on the total amount of the tetracarboxylic dianhydride component (a1) being 100 mol, the usage amount of the alicyclic tetracarboxylic dianhydride compound (a1-1) represented by the formula (A11) is 30 mol to 100 mol, preferably, the usage amount of the alicyclic tetracarboxylic dianhydride compound (a1-1) represented by the formula (A11) is 40 mol to 100 mol, more preferably, the usage amount of the alicyclic tetracarboxylic dianhydride compound (a1-1) represented by the formula (A11) is 50 mol to 100 mol.

[0064] ﹝Other tetracarboxylic dianhydride compounds (a1-2)﹞

[0065] In some embodiments of the present invention, the tetracarboxylic dianhydride component (a1) further comprises other tetracarboxylic dianhydride compounds (a1-2).

[0066] In some embodiments of the present invention, the other tetracarboxylic dianhydride compound (a1-2) comprises a tetracarboxylic dianhydride compound represented by formula (A12) or a derivative thereof.

[0067]

[0068] In the formula (A12), X 1 ' represents the structures shown in Formula (A12-1) to Formula (A12-32), and "*" represents the bonding position.

[0069]

[0070]

[0071]

[0072] In the formula (A12-1), a1 is 1 to 12. In the formula (A12-5), X 11 ' represents a single bond, -O-, -CO-, -COO-, phenylene, sulfonyl or amide, and a1 represents 0 or 1. In the formula (A12-6), X 11 ' and X 12 'respectively independently represent a single bond, -O-, -CO-, -COO-, phenylene, sulfonyl or amide, and multiple X 12 ' are the same or different, and a1 represents 0 or 1. In the formula (A12-11), a1 represents 2 to 6. In the formula (A12-13), a1 represents 1 to 2. In the formula (A12-14), X 13 'respectively independently represent hydrogen, halogen, 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 containing fluorine and having 1 to 6 carbon atoms, or a phenyl group, and multiple X13 ' are the same or different. Based on the viewpoint of liquid crystal alignment, preferably, the X 13 'respectively independently represent hydrogen, halogen, methyl or ethyl, more preferably, the X 13 ' respectively independently represent hydrogen or methyl.

[0073] In some embodiments of the present invention, the formula (A12-5) and the formula (A12-6) include but are not limited to

[0074]

[0075] The other tetracarboxylic dianhydride compounds (a1-2) can be used alone or in combination. In some embodiments of the present invention, based on the total amount of the tetracarboxylic dianhydride component (a1) being 100 moles, the usage amount of the other tetracarboxylic dianhydride compounds (a1-2) is 0 mole to 70 moles, preferably, the usage amount of the other tetracarboxylic dianhydride compounds (a1-2) is 0 mole to 60 moles, and more preferably, the usage amount of the other tetracarboxylic dianhydride compounds (a1-2) is 0 mole to 50 moles.

[0076] [Diamine component (b1)]

[0077] [Diamine compound (b 1-1)]

[0078] In some embodiments of the present invention, the diamine component (b1) comprises a diamine compound (b1-1), and the diamine compound (b1-1) is a diamine compound represented by Formula (A21-1) or Formula (A21-2).

[0079]

[0080] In the formula (A21-1), Y 21 represents a divalent organic group as shown in formula (A21-3), and multiple Y 22 Each independently represents hydrogen or an alkyl group having 1 to 6 carbon atoms. 23 Each independently represents a divalent organic group represented by formula (A21-3').

[0081]

[0082] In the divalent organic group represented by formula (A21-3), Ar independently represents a divalent benzene ring, biphenyl structure or naphthalene ring, and the hydrogen atoms of the benzene ring, biphenyl structure or naphthalene ring may be substituted with a monovalent substituent or may be unsubstituted; Y 21 ' represents -(CH2) n-, n represents an integer from 2 to 18, and -(CH2) n At least one -CH2- in - may be substituted by -O-, -C(=O)- or -OC(=O)- or may be unsubstituted; p1 represents 0 or 1; "*" represents a bonding position.

[0083] In the divalent organic group represented by formula (A21-3'), Ar' independently represents a divalent benzene ring or a biphenyl structure, and the hydrogen atoms of the benzene ring or biphenyl structure may be substituted with a monovalent substituent or may not be substituted; Y 23 ' represents -(CH2) n -, n represents an integer from 2 to 18, and -(CH2) n At least one -CH2- in - may be substituted by -O-, -C(=O)- or -OC(=O)- or may be unsubstituted; p2 represents 0 or 1; "*" represents a bonding position.

[0084] In the divalent organic group represented by the formula (A21-3) and the divalent organic group represented by the formula (A21-3'), the monovalent substituent group of the benzene ring, biphenyl structure, or naphthalene ring is, for example, a halogen, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluoroalkyl group having 1 to 10 carbon atoms, a fluoroalkenyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, a carboxyl group, a hydroxyl group, an alkoxycarbonyl group having 1 to 10 carbon atoms, a cyano group, or a nitro group.

[0085] In some embodiments of the present invention, based on the viewpoint of improving the liquid crystal alignment, preferably, the divalent organic group represented by formula (A21-3) is at least one of the groups represented by formula (A21-3-1) to formula (A21-3-16), and "*" represents the bonding position.

[0086]

[0087]

[0088]

[0089] In the formula (A21-3-1), m is 0 to 1, and n is 1 to 6. In the formula (A21-3-2), n is 1 to 6. In the formula (A21-3-3), n is 2 to 6. In the formula (A21-3-4), n is 1 to 6. In the formula (A21-3-5), n is 1 to 6. In the formula (A21-3-6), n is 2 to 6. In the formula (A21-3-7), n is 1 to 6. In the formula (A21-3-8), n is 1 to 6. In the formula (A21-3-9), n is 2 to 6. In the formula (A21-3-10), m is 1 to 3, and n is 1 to 4. In the formula (A21-3-11), n ​​is 1 to 6. In the formula (A21-3-12), n is 1 to 6. In the formula (A21-3-13), m is 0 to 1, and n is 1 to 6. In the formula (A21-3-14), m is 1 to 3, and n is 1 to 4.

[0090] In some embodiments of the present invention, based on the viewpoint of improving the liquid crystal alignment, preferably, the divalent organic group represented by formula (A21-3') is at least one of the groups represented by formulas (A21-3-7) to (A21-3-16).

[0091] When the diamine compound (b1-1) comprises a plurality of diamine compounds represented by formula (A21-1), preferably, the diamine compound represented by formula (A21-1) is Y in formula (A21-1). 21 The diamine compounds of formula (A21-3-1) to formula (A21-3-14) and Y in formula (A21-1) are represented by 21 It represents a combination of diamine compounds of formula (A21-3-15) to formula (A21-3-16).

[0092] In some embodiments of the present invention, the diamine compound represented by formula (A21-2) is, for example but not limited to, the diamine compounds represented by formula (A21-2-1) to formula (A21-2-5).

[0093]

[0094]

[0095] In the formula (A21-2-1), m is 1 to 6, and n is 1 to 6. In the formula (A21-2-2), m is 1 to 6, and n is 1 to 6. In the formula (A21-2-3), m is 2 to 6, and n is 2 to 6.

[0096] The diamine compound (b1-1) can be used alone or in combination. In some embodiments of the present invention, based on 100 mol of the total amount of the diamine component (b1), the amount of the diamine compound (b1-1) used is 20 mol to 90 mol. Preferably, the amount of the diamine compound (b1-1) used is 25 mol to 80 mol. More preferably, the amount of the diamine compound (b1-1) used is 30 mol to 70 mol.

[0097] ﹝Diamine compound (b 1-2)﹞

[0098] In some embodiments of the present invention, the diamine component (b1) further comprises a diamine compound (b1-2) having a group of -N(D)-.

[0099] Based on the viewpoint of improving the voltage holding rate of the liquid crystal display element, the molecular structure of the first polymer (A1) may selectively have an -N(D)- group (D represents a carbamate-based protective group). The first polymer (A1) having an -N(D)- group can be obtained by a method in which a monomer having an -N(D)- group is used as at least a part of the reaction raw material, or by a method in which a monomer having an -N(D)- group is used as the following end-capping agent. In some specific examples of the present invention, the monomer having an -N(D)- group is, for example, a diamine compound (b 1-2) having an -N(D)- group. For example, the carbamate-based protective group is, for example, but not limited to, a tert-butyloxycarbonyl group (Boc for short) or a 9-fluorenylmethoxycarbonyl group.

[0100] In some embodiments of the present invention, preferably, the diamine compound (b1-2) having an -N(D)- group comprises a diamine compound having at least one aromatic group (e.g., a benzene ring). More preferably, the diamine compound (b1-2) having an -N(D)- group comprises a diamine compound having at least one aromatic group and having a carbon number of 6 to 30 in the residue other than the substituent (D). In some specific examples of the present invention, the diamine compound (b1-2) having an -N(D)- group is, for example, but not limited to, a diamine compound represented by Formula (A22-1) to Formula (A22-10).

[0101]

[0102]

[0103] In Formula (A22-1), n ​​is 1 to 6. In Formula (A22-2), n is 1 to 6. In Formula (A22-4), m is 1 to 6, and n is 1 to 6. In Formula (A22-7), m is 1 to 6, and n is 1 to 6. In Formula (A22-9), n is 1 to 6.

[0104] The diamine compound (b1-2) having an -N(D)- group can be used alone or in combination. In some embodiments of the present invention, based on 100 mol of the total amount of the diamine component (b1), the amount of the diamine compound (b1-2) having an -N(D)- group is 2 to 60 mol. Preferably, the amount of the diamine compound (b1-2) having an -N(D)- group is 10 to 50 mol. More preferably, the amount of the diamine compound (b1-2) having an -N(D)- group is 15 to 40 mol.

[0105] ﹝Other diamine compounds (b 1-3)﹞

[0106] In some embodiments of the present invention, the diamine component (b1) further comprises other diamine compounds (b1-3).

[0107] The other diamine compounds (b1-3) include, but are not limited to, diamine compounds having a photoalignment group, 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol, diamine compounds having a carboxyl group, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ketone, 1,4-bis(4-aminophenyl)-1,4-diaminodiphenylmethane, 1,4' ... 1-(4-aminophenyl)-1,3,3-trimethyl-1H-dihydroindene-5-amine, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indene-6-amine, a diamine compound having a urea bond, a diamine compound having an amide bond, a diamine compound having a photopolymerizable group at the end, a diamine compound having a siloxane bond, or a diamine compound having an oxazoline structure.

[0108] The diamine compound having a photoalignment group is, for example but not limited to, 4,4′-diaminoazobenzene, or diamine compounds represented by Formula (A23-1) to Formula (A23-3).

[0109]

[0110] The diamine compound having a carboxyl group is, for example but not limited to, 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, 3,5-diaminobenzoic acid, or diamine compounds represented by formula (A23-4) to formula (A23-7).

[0111]

[0112]

[0113] In the formula (A23-4), Y 31 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-; m1 and m2 each independently represent an integer from 0 to 4, and (m1+m2) represents an integer from 1 to 4. In the formula (A23-5), m3 and m4 each independently represent an integer from 1 to 5. In the formula (A23-6), Y 32 represents a linear or branched alkyl group having 1 to 5 carbon atoms; m5 represents an integer from 1 to 5. In the formula (A23-7), Y 33 and Y 34 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-; m6 represents an integer from 1 to 4.

[0114] The diamine compound having a urea bond is, for example but not limited to, the diamine compounds represented by Formula (A23-8) to Formula (A23-10).

[0115]

[0116] In the formula (A23-8), n1 is 0 to 6, and n2 is 1 to 6. In the formula (A23-9), n1 is 1 to 6, and n2 is 1 to 6. In the formula (A23-10), n is 1 to 6.

[0117] The diamine compound having an amide bond is, for example, but not limited to, the diamine compounds represented by Formula (A23-11) to Formula (A23-13).

[0118]

[0119]

[0120] In the formula (A23-12), n is 1 to 6. In the formula (A23-13), n1 is 1 to 6, and n2 is 1 to 6.

[0121] The diamine compound having a photopolymerizable group at the end thereof can be, for example but not limited to, 2-(2,4-diaminophenoxy)ethyl methacrylate or 2,4-diamino-N,N-diallylaniline.

[0122] The diamine compound having a siloxane bond is, for example, but not limited to, 3-bis(3-aminopropyl)-tetramethyldisiloxane.

[0123] The diamine compound having an oxazoline structure is, for example but not limited to, the diamine compounds represented by Formula (A23-14) to Formula (A23-15).

[0124]

[0125] The other diamine compounds (b1-3) can be used alone or in combination. In some embodiments of the present invention, based on 100 mol of the total amount of the diamine component (b1), the amount of the other diamine compounds (b1-3) used is 0 mol to 65 mol. Preferably, the amount of the other diamine compounds (b1-3) used is 0 mol to 50 mol. More preferably, the amount of the other diamine compounds (b1-3) used is 0 mol to 35 mol.

[0126] <Second polymer (A2)>

[0127] The second polymer (A2) is at least one selected from the group consisting of a polyimide precursor and an imidized polymer formed from the polyimide precursor. The polyimide precursor of the second polymer (A2) comprises a structure represented by formula (II).

[0128]

[0129] In the formula (II), V 1 Represents the structure shown in formula (II-1), "*" represents the bonding position, V 2 represents hydrogen or an alkyl group having 1 to 4 carbon atoms, V 3 represents hydrogen or an alkyl group having 1 to 4 carbon atoms, W 1 It represents the structure represented by formula (II-2).

[0130]

[0131] In the formula (II-2), R 1to R 10 At least two of them are “*” representing bonding positions, and the rest are H or monovalent organic groups.

[0132] In some embodiments of the present invention, the polyimide precursor of the second polymer (A2) is formed by reacting a reaction composition comprising a tetracarboxylic dianhydride component (a2) and a diamine component (b2), and the tetracarboxylic dianhydride component (a2) comprises V in the structure represented by the formula (II). 1 The diamine component (b2) comprises W in the structure shown in the formula (II) 1 .

[0133] [Tetracarboxylic dianhydride component (a2)]

[0134] [Tetracarboxylic dianhydride compound (a2-1)]

[0135] In some embodiments of the present invention, the tetracarboxylic dianhydride component (a2) comprises a tetracarboxylic dianhydride as shown in formula (A12) and X 1 ' is a tetracarboxylic dianhydride compound (a2-1) having a structure represented by formula (II-1).

[0136]

[0137] In the formula (II-1), “*” represents a bonding position.

[0138] In some embodiments of the present invention, based on the total usage of the tetracarboxylic dianhydride component (a2) being 100 mol, the usage of the tetracarboxylic dianhydride compound (a2-1) is 50 mol to 100 mol, preferably, the usage of the tetracarboxylic dianhydride compound (a2-1) is 60 mol to 100 mol, and more preferably, the usage of the tetracarboxylic dianhydride compound (a2-1) is 70 mol to 100 mol.

[0139] When the tetracarboxylic dianhydride component (a2) does not contain the tetracarboxylic dianhydride compound (a2-1), the liquid crystal display element comprising the liquid crystal alignment film formed by the liquid crystal alignment agent for the photoalignment method has high flicker after high voltage driving.

[0140] [Diamine component (b2)]

[0141] The diamine component (b2) includes, but is not limited to, the diamine component (b1) of the first polymer (A1), the diamine compound (b2-1), or the diamine compound (b2-2) having a nitrogen-containing structure. The diamine component (b2) can be used alone or in combination of multiple types.

[0142] ﹝Diamine compound (b2-1)﹞

[0143] In some embodiments of the present invention, the diamine component (b2) comprises a diamine compound (b2-1) having a structure as shown in formula (II-2).

[0144]

[0145] In the formula (II-2), R 1 to R 10 Two of them are -NH2, and the rest are hydrogen or monovalent organic groups other than -NH2, and are the same or different.

[0146] In some embodiments of the present invention, the diamine compound (b2-1) is, for example but not limited to, a diamine compound having a structure as represented by formula (III) or a diamine compound having a structure as represented by formula (IV).

[0147]

[0148] In some embodiments of the present invention, in Formula (III) and Formula (IV), the hydrogen atoms on the benzene ring may be replaced by a monovalent organic group other than -NH2. The monovalent organic group other than -NH2 may be, but is not limited to, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group, a phenyl group, a biphenyl group, a terphenyl group, a fluorine group, or any combination thereof.

[0149] In some embodiments of the present invention, based on the viewpoint of improving the liquid crystal alignment, preferably, the diamine compound (b2-1) is selected from 4,4'-diaminodiphenylamine and 2,4-diaminodiphenylamine, and more preferably, the diamine compound (b2-1) is 4,4'-diaminodiphenylamine.

[0150] In some embodiments of the present invention, based on the total usage of the diamine component (b2) being 100 moles, the usage of the diamine compound (b2-1) is 50 moles to 100 moles, preferably, the usage of the diamine compound (b2-1) is 60 moles to 100 moles, and more preferably, the usage of the diamine compound (b2-1) is 70 moles to 100 moles.

[0151] When the diamine component (b2) does not include the diamine compound (b2-1), a liquid crystal display element comprising a liquid crystal alignment film formed of the liquid crystal alignment agent for the photoalignment method has high flicker after high voltage driving.

[0152] [Diamine compound having a nitrogen atom-containing structure (b2-2)]

[0153] The nitrogen-containing atom structure in the diamine compound (b2-2) having a nitrogen-containing atom structure is at least one selected from the group consisting of a nitrogen-containing heterocycle, a secondary amino group, and a tertiary amino group, and the diamine component (b2-2) does not include the diamine compound (b2-1).

[0154] The nitrogen-containing heterocyclic ring of the diamine compound (b2-2) having a nitrogen-containing structure is, for example but not limited to, pyrrole, imidazole, pyrazole, triazole, pyridine, pyrimidine, pyridazine, pyrazine, indole, benzimidazole, purine, quinoline, isoquinoline, naphthyridine, quinoxaline, phthalazine, triazine, carbazole, acridine, piperidine, piperazine, pyrrolidine, or hexamethyleneimine. Preferably, the nitrogen-containing heterocyclic ring is pyridine, pyrimidine, pyrazine, piperidine, piperazine, quinoline, carbazole, or acridine.

[0155] In some embodiments of the present invention, the nitrogen-containing atom structure in the diamine compound (b2-2) having a nitrogen-containing atom structure is a secondary amine group and a tertiary amine group represented by formula (B21).

[0156]

[0157] In the formula (B21), Z represents hydrogen, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, or an aryl group; and "*" represents a bonding position.

[0158] The alkyl group having 1 to 10 carbon atoms is exemplified by, but not limited to, methyl, ethyl, or propyl. The cycloalkyl group is exemplified by, but not limited to, cyclohexyl. The aryl group is exemplified by, but not limited to, phenyl or tolyl. Preferably, Z is hydrogen or methyl.

[0159] In some embodiments of the present invention, the diamine compound (b2-2) having a nitrogen atom structure is, for example, but not limited to, 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, diamine compounds represented by formula (B21-1) to formula (B21-7), or diamine compounds represented by formula (B21-8) to formula (B21-25).

[0160]

[0161]

[0162]

[0163] In the formula (B21-4), n represents 1 to 4. In the formula (B21-5), n represents 1 to 4. The diamine compound (b2-2) having a nitrogen atom-containing structure may be used alone or in combination of two or more.

[0164] In some embodiments of the present invention, based on the total amount of the diamine component (b2) being 100 moles, the usage amount of the diamine compound having a nitrogen atom structure (b2-2) is 0 mole to 90 moles, preferably, the usage amount of the diamine compound having a nitrogen atom structure (b2-2) is 10 moles to 85 moles, and more preferably, the usage amount of the diamine compound having a nitrogen atom structure (b2-2) is 20 moles to 80 moles.

[0165] In some embodiments of the present invention, based on 100 parts by weight of the total amount of the polymer component (A), the amount of the first polymer (A1) is 5 to 85 parts by weight, preferably 10 to 80 parts by weight, and more preferably 10 to 75 parts by weight; and the amount of the second polymer (A2) is 15 to 95 parts by weight, preferably 20 to 90 parts by weight, and more preferably 25 to 90 parts by weight. When the amounts of the first polymer (A1) and the second polymer (A2) are both within the above ranges, a liquid crystal display device comprising a liquid crystal alignment film formed with the liquid crystal alignment agent for photo-alignment has lower flicker after high voltage driving.

[0166] <Method for preparing the first polymer (A1) and the second polymer (A2)>

[0167] The manufacture of the first polymer (A1) and the second polymer (A2) can be carried out by reacting the above-mentioned tetracarboxylic dianhydride component and diamine component in a solvent (condensation polymerization). When a part of the first polymer (A1) and the second polymer (A2) has an amic acid structure, for example, by reacting the tetracarboxylic dianhydride component with the diamine component to obtain a polymer (i.e., polyamic acid) with an amic acid structure. The solvent is not particularly limited and only needs to be able to dissolve the formed polymer. For example, the solvent is such as, but not limited to, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or 1,3-dimethyl-2-imidazolidinone. In some embodiments of the present invention, when the solvent solubility of the polymer is high, the solvent is such as methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or a solvent as shown in formula (D-1) to formula (D-3).

[0168]

[0169] HO—CH2-CH2-OZ 2 Formula (D-2),

[0170] HO-CH2-CH2-O-CH2-CH2-OZ 3 Formula (D-3)

[0171] In the formula (D-1), Z 1 represents an alkyl group having 1 to 3 carbon atoms. In the formula (D-2), Z 2 represents an alkyl group having 1 to 3 carbon atoms. In the formula (D-3), Z 3 It represents an alkyl group having 1 to 4 carbon atoms.

[0172] The solvent can be used alone or in combination. Secondly, even if it is a solvent that cannot dissolve the polymer, the solvent that cannot dissolve the polymer can still be mixed with the above-mentioned solvent in the range that the generated polymer will not precipitate. When the diamine component and the tetracarboxylic dianhydride component react in a solvent, the reaction can be carried out at any concentration. Preferably, the total concentration of the diamine component and the tetracarboxylic dianhydride component is 1wt% to 50wt%, and more preferably, the total concentration of the diamine component and the tetracarboxylic dianhydride component is 5wt% to 30wt%. The reaction can also be carried out at a high concentration initially, and then, an additional solvent is added. When reacting, preferably, the ratio of the total moles of the diamine component to the total moles of the tetracarboxylic dianhydride component is 0.8 to 1.2. Similar to general polycondensation reactions, the closer the ratio of the total moles of the diamine component to the total moles of the tetracarboxylic dianhydride component is to 1.0, the greater the molecular weight of the first polymer (A1) or the second polymer (A2) formed.

[0173] The polymer having an amic acid ester structure can be obtained, for example, by conventional methods, and the conventional methods include (1) a method of reacting the polyamic acid obtained by the above method with an esterifying agent, (2) a method of reacting a tetracarboxylic acid diester compound with a diamine compound, or (3) a method of reacting a tetracarboxylic acid diester dihalide with a diamine compound.

[0174] The imidized polymer in the first polymer (A1) or the second polymer (A2) of the liquid crystal alignment agent for the photo-alignment method of the present invention can be obtained, for example, by subjecting the polymer having an amic acid ester structure to a closed loop. In the imidized polymer, the closed loop ratio (also referred to as the imidization ratio) of the functional groups possessed by the amic acid groups or their derivatives does not necessarily need to be 100%. The imidization ratio of the imidized polymer can be arbitrarily adjusted according to the application and / or purpose.

[0175] Methods for obtaining an imidized polymer include, for example, thermal imidization by directly heating a solution containing a polymer having an amic acid ester structure, or catalytic imidization by adding a catalyst to the solution containing a polymer having an amic acid ester structure. When thermal imidization is performed in the solution containing a polymer having an amic acid ester structure, the temperature is preferably 100°C to 400°C, more preferably 120°C to 250°C. During thermal imidization, water generated by the imidization reaction is preferably removed from the system.

[0176] The catalytic imidization is carried out, for example, by adding a basic catalyst and an acid anhydride to the solution containing the polymer having an amic acid ester structure. Preferably, stirring is carried out at a temperature between -20°C and 250°C, more preferably, at a temperature between 0°C and 180°C. Preferably, the amount of the basic catalyst added is 0.5 to 30 times the molar equivalent of the amic acid group, more preferably, 2 to 20 times the molar equivalent of the amic acid group. Preferably, the amount of the acid anhydride added is 1 to 50 times the molar equivalent of the amic acid group, more preferably, 3 to 30 times the molar equivalent of the amic acid group. The basic catalyst may be, but is not limited to, pyridine, triethylamine, trimethylamine, tributylamine, or trioctylamine. Pyridine is ideal because it has a moderate alkalinity that facilitates the reaction. The acid anhydride may be, but is not limited to, acetic anhydride, trimellitic anhydride, or pyromellitic anhydride. Using acetic anhydride is ideal because it facilitates purification after the reaction. The imidization rate of the catalytic imidization can be controlled by adjusting the amount of catalyst, reaction temperature and / or reaction time.

[0177] When the imidized polymer is recovered from the above-mentioned imidized reaction solution, the reaction solution is put into a solvent and precipitated. The solvent used for precipitation is, for example, but not limited to, methanol, ethanol, isopropanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, toluene, benzene or water. After filtering and recovering the polymer precipitated by the solvent, it can be dried at room temperature or under normal pressure or reduced pressure. Alternatively, the precipitated polymer is dissolved in a solvent and reprecipitated and recovered. This operation is repeated 2 to 10 times to reduce impurities in the polymer. The solvent used can be, for example, an alcohol or a ketone hydrocarbon. If more than three solvents selected therefrom are used, the efficiency of the refining can be further improved, so it is more ideal.

[0178] When a solution containing 10 to 15 wt% of the first polymer (A1) or the second polymer (A2) is prepared, the solution viscosity of the first polymer (A1) or the second polymer (A2) of the present invention is not particularly limited. For ease of handling, the solution viscosity may be, for example, 10 to 1000 mPa·s. The polymer solution viscosity (mPa·s) is a value measured at 25°C using an E-type rotational viscometer using a good solvent for the polymer (e.g., γ-butyrolactone or N-methyl-2-pyrrolidone) to prepare a polymer solution containing 10 to 15 wt% of the polymer.

[0179] In some embodiments of the present invention, the weight average molecular weight (Mw) of the first polymer (A1) or the second polymer (A2) of the present invention, as measured by gel permeation chromatography (GPC), is preferably from 1,000 to 500,000, more preferably from 2,000 to 500,000. Furthermore, the molecular weight distribution (Mw / Mn), represented by the ratio of Mw to the number average molecular weight (Mn) as measured by GPC, is preferably 15 or less, more preferably 10 or less. When the weight average molecular weight and number average molecular weight of the polymers are within the above molecular weight ranges, good alignment and stability of the liquid crystal display device can be ensured.

[0180] In some embodiments of the present invention, when synthesizing the first polymer (A1) or the second polymer (A2) of the present invention, the tetracarboxylic dianhydride component and the diamine component as described above can be used, and an appropriate end-capping agent can be used to synthesize an end-sealed polymer. The end-sealed polymer has the effect of improving the film hardness of the liquid crystal alignment film obtained by using the coating, and improving the sealing properties of the sealant and the liquid crystal alignment film. The end of the first polymer (A1) or the second polymer (A2) of the present invention can be, for example, an amino group, a carboxyl group, an anhydride group or the derivatives thereof. The amino group, carboxyl group, anhydride group or the derivatives thereof can be obtained by a general condensation reaction, or by sealing the end using the following end-capping agent. Similarly, the above-mentioned derivatives can be obtained, for example, using the following end-capping agent.

[0181] The end-capping agent may be, for example, but not limited to, an acid anhydride, a dicarbonic acid diester compound, a chlorocarbonyl compound, a monoamine compound, or a monoisocyanate compound. The acid anhydride may be, for example, but not limited to, acetic anhydride, maleic anhydride, Nadic anhydride, phthalic anhydride, itaconic anhydride, cyclohexanedicarboxylic anhydride, 3-hydroxyphthalic anhydride, trimellitic anhydride, 3-((3-trimethoxysilyl)propyl)-3,4-dihydrofuran-2,5-dione, 4,5,6,7-tetrafluoroisobenzofuran-1,3-dione, or 4-ethynylphthalic anhydride. The dicarbonic acid diester compound may be, for example, but not limited to, di-tert-butyl dicarbonate or diallyl dicarbonate. The chlorocarbonyl compound may be, for example, but not limited to, acryloyl chloride, methacryloyl chloride, or nicotinyl chloride. The monoamine compound includes, but is not limited to, aniline, 2-aminophenol, 3-aminophenol, 4-aminosalicylic acid, 5-aminosalicylic acid, 6-aminosalicylic acid, 2-aminobenzoic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, or n-octylamine. The monoisocyanate compound includes, but is not limited to, ethyl isocyanate, phenyl isocyanate, or naphthyl isocyanate.

[0182] The end-capping agent can be used alone or in combination. In some embodiments of the present invention, preferably, based on 100 parts by mole of the total amount of the diamine component, the amount of the end-capping agent used is 0.01 to 20 parts by mole, more preferably, the amount of the end-capping agent used is 0.01 to 10 parts by mole.

[0183] The polymer component (A) of the liquid crystal alignment agent of the present invention may optionally further comprise other polymers, such as, but not limited to, polyesters, polyamides, polyureas, polyorganosiloxanes, cellulose derivatives, polyacetals, polystyrene or its derivatives, poly(styrene-phenylmaleimide) derivatives, or poly(meth)acrylates.

[0184] Solvent (B)

[0185] Based on the viewpoint of forming a uniform thin film, the liquid crystal alignment agent takes the form of a coating liquid to produce a liquid crystal alignment film. Preferably, the liquid crystal alignment agent used in the optical alignment method of the present invention is a coating liquid containing a polymer component (A) and a solvent (B). Based on the set thickness of the coating to be formed, the concentration of the polymer component (A) in the liquid crystal alignment agent used in the optical alignment method can be appropriately changed. Based on the viewpoint of forming a uniform and defect-free coating, preferably, the concentration of the polymer component (A) in the liquid crystal alignment agent used in the optical alignment method is 1wt% or more. Based on the viewpoint of the storage stability of the solution, preferably, the concentration of the polymer component (A) in the liquid crystal alignment agent used in the optical alignment method is 10wt% or less. The ideal concentration of the polymer component (A) is 2wt% to 8wt%. The content of the polymer component (A) in the liquid crystal alignment agent used in the photo-alignment method can be appropriately changed by the coating method of the liquid crystal alignment agent and / or the film thickness of the desired liquid crystal alignment film. Preferably, the content of the polymer component (A) is 2wt% to 10wt%, and more preferably, the content of the polymer component (A) is 3wt% to 8wt%.

[0186] The solvent (B) is, for example, an organic solvent, and there is no particular limitation on the solvent (B), as long as it can uniformly dissolve the polymer component (A). The solvent (B) is, for example, but not limited to, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyllactamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, γ-valerolactone, 1,3-dimethyl-2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide The solvents include amine, 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, or N-cyclohexyl-2-pyrrolidone, and the like. These solvents are also referred to as good solvents. N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide, or γ-butyrolactone are preferred. In some embodiments of the present invention, based on the total amount of solvent (B) in the liquid crystal alignment agent used in the photo-alignment method being 100 wt%, the amount of the good solvent used is 20 wt% to 99 wt%, preferably, the amount of the good solvent used is 20 wt% to 90 wt%, and more preferably, the amount of the good solvent used is 30 wt% to 80 wt%.

[0187] In some embodiments of the present invention, preferably, the solvent (B) comprises the above-mentioned good solvent and a poor solvent that can improve the coating properties and surface smoothness of the coating film during the application of the liquid crystal alignment agent. Preferably, based on the total amount of the solvent (B) being 100wt%, the amount of the poor solvent used is 1wt% to 80wt%, more preferably, the amount of the poor solvent used is 10wt% to 80wt%, and even more preferably, the amount of the poor solvent used is 20wt% to 70wt%. The type and amount of the poor solvent used can be appropriately selected based on the coating device, coating conditions, and / or coating environment of the liquid crystal alignment agent.

[0188] The poor solvents include, but are not limited to, diisopropyl ether, diisobutyl ether, diisobutyl carbinol (2,6-dimethyl-4-heptanol), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, ethylene glycol monobutyl ether (butyl cellosolve), ethylene glycol monoisopentyl ether, ethylene glycol monohexyl ether, propylene glycol monobutyl ether, 1-(2-butoxyethoxy) -2-propanol, 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, or diisobutyl ketone (2,6-dimethyl-4-heptanone), etc. Preferably, the poor solvent is diisobutyl carbinol, propylene glycol monobutyl ether, propylene glycol diacetate, diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, or diisobutyl ketone.

[0189] In some embodiments of the present invention, preferably, the solvent combination of the good solvent and the poor solvent is, for example, but not limited to, 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-ethyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone; N-ethyl-2-pyrrolidone and propylene glycol diacetate; N,N-dimethyllactamide and diisobutyl ketone; N-methyl-2-pyrrolidone and ethyl 3-ethoxypropionate; N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate ; N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether acetate; N-ethyl-2-pyrrolidone and dipropylene glycol dimethyl ether; N,N-dimethyl lactamide and ethylene glycol monobutyl ether; N,N-dimethyl lactamide and propylene glycol diacetate; N-ethyl-2-pyrrolidone and diethylene glycol diethyl ether; N,N-dimethyl lactamide and diethylene glycol diethyl ether; N-methyl-2-pyrrolidone, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and diethylene glycol diethyl ether; N-ethyl-2-pyrrolidone, N-methyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone; N-ethyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone and propylene glycol monobutyl ether; N-methyl N-Methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone and diisobutyl ketone; N-Methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone and dipropylene glycol monomethyl ether; N-Methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone and propylene glycol monobutyl ether; N-Methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone and propylene glycol diacetate; γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and diisobutyl ketone; γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and propylene glycol diacetate; N-Methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether and diisobutyl ketone; N-Methyl-2-pyrrolidone, γ- N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisopropyl ether; N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisobutyl carbinol; N-methyl-2-pyrrolidone, γ-butyrolactone, and dipropylene glycol dimethyl ether; N-methyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol dimethyl ether; N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol monomethyl ether; N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and propylene glycol diacetate; N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and diisobutyl ketone; N-ethyl-2-pyrrolidone, γ-butyrolactone, and diisobutyl ketone; or N-ethyl-2-pyrrolidone, N,N-dimethyllactamide, and diisobutyl ketone, etc.

[0190] The solvent (B) can be used alone or in combination. In some embodiments of the present invention, based on 100 parts by weight of the total amount of the polymer component (A), the amount of the solvent (B) used is 800 to 4,000 parts by weight, preferably 900 to 3,500 parts by weight, and more preferably 1,000 to 3,000 parts by weight.

[0191] Additives (C)

[0192] In some embodiments of the present invention, the liquid crystal alignment agent for the photo-alignment method of the present invention further comprises an additive (C). The additive (C) includes, but is not limited to, an adhesion promoter for improving the adhesion between the liquid crystal alignment film and the substrate or between the liquid crystal alignment film and the sealant, a cross-linking compound for improving the strength of the liquid crystal alignment film, a compound for promoting imidization, a dielectric or conductive substance for adjusting the dielectric constant or resistance of the liquid crystal alignment film, and the like.

[0193] The adhesion aids include, but are not limited to, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, vinyltrimethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltrieth ... Silane coupling agents include silane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, tris(3-trimethoxysilylpropyl)isocyanurate, and 3-isocyanatepropyltriethoxysilane. When using the bonding aid, based on the viewpoint of exhibiting good resistance to AC ghosting, preferably, the amount of the bonding aid used is 0.1 to 30 parts by weight relative to the total amount of the polymer component (A) used being 100 parts by weight, and more preferably, the amount of the bonding aid used is 0.1 to 20 parts by weight.

[0194] Based on the viewpoint of exhibiting good resistance to AC ghosting and effectively improving film strength, the cross-linking compound is a compound having an ethylene oxide group, a propylene oxide group, at least one group selected from the group consisting of a group represented by formula (E1) and a group represented by formula (E2), or a compound selected from the compound represented by formula (E3).

[0195]

[0196] In the formula (E1), G 1 and G 2 Each independently represents hydrogen, an alkyl group having 1 to 3 carbon atoms, or -CH2-OH. In the formula (E2), G 3 represents 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, G 4 represents hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkynyl group having 2 to 6 carbon atoms. 5 Represents a (g1+g2) valent organic group containing an aromatic ring, G 6 represents hydrogen or an alkyl group having 1 to 5 carbon atoms, g1 represents an integer from 1 to 6, and g2 represents an integer from 0 to 4.

[0197] In the formula (E3), G 5 The (g1+g2) valent organic group having an aromatic ring is, for example, a (g1+g2) valent aromatic hydrocarbon group having 6 to 30 carbon atoms, an aromatic hydrocarbon group having 6 to 30 carbon atoms directly or intermittently connected to form a (g1+g2) valent organic group, or a (g1+g2) valent group having an aromatic heterocycle. The aromatic hydrocarbon is, for example, benzene or naphthalene. The aromatic heterocycle is, for example, the aromatic heterocycle exemplified by the nitrogen-containing atom structure described above. The connecting group is, for example, an alkylene group having 1 to 10 carbon atoms or a group that removes a hydrogen atom from the alkylene group, or a divalent or trivalent cyclohexane. Any hydrogen of the alkylene group may also be replaced by an organic group such as a fluorine atom or a trifluoromethyl group. In the formula (E3), G 6 The represented alkyl group having a carbon number of 1 to 5 is exemplified by methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl or n-pentyl.

[0198] The compound having an oxirane group is, for example but not limited to, N,N,N',N'-tetraepoxypropyl-m-xylene diamine, 1,3-bis(N,N-diepoxypropylaminomethyl)cyclohexane, N,N,N',N'-tetraepoxypropyl-4,4'-diaminodiphenylmethane, N,N,N',N'-tetraepoxypropyl-p-phenylenediamine, or nitrogen-containing compounds as shown in Formula (E4) to Formula (E6), etc.

[0199]

[0200] The compound having an propylene oxide group is, for example but not limited to, compounds represented by formula (E7) to formula (E16).

[0201]

[0202]

[0203] In the formula (E7), n represents 1 to 3. In the formula (E13), n represents 1 to 3. In the formula (E14), n represents 1 to 100. In the formula (E15), R represents "*" represents a bonding position. In the formula (E16), n represents 1 to 10.

[0204] The compound having the group represented by formula (E1) includes, but is not limited to, compounds represented by formula (E1-1) to formula (E1-12).

[0205]

[0206]

[0207] The compound having a group represented by formula (E2) includes, but is not limited to, compounds represented by formula (E2-1) to formula (E2-4).

[0208]

[0209] In the formula (E2-1), n ​​represents 2 to 16. In the formula (E2-2), n represents 2 to 16.

[0210] The compound having a group represented by formula (E3) includes, but is not limited to, compounds represented by formula (E3-1) to formula (E3-10).

[0211]

[0212]

[0213] In some embodiments of the present invention, the crosslinking compound is preferably used in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of the total amount of the polymer component (A). More preferably, the crosslinking compound is used in an amount of 1 to 15 parts by weight, based on the crosslinking reaction and good resistance to AC image sticking.

[0214] In some embodiments of the present invention, the compound used to promote imidization is a compound having a basic site [e.g., a primary amine group, an aliphatic heterocycle (e.g., a pyrrolidine skeleton), an aromatic heterocycle (e.g., an imidazole ring or an indole ring), or a guanidine group] (excluding the cross-linking compound and the adhesion promoter described above), or a compound that generates such a basic site upon calcination. More preferably, the compound used to promote imidization is a compound that generates such a basic site upon calcination, such as an amino acid in which some or all of the basic sites are protected. Such amino acids include glycine, alanine, cysteine, methionine, asparagine, glutamine, valine, leucine, phenylalanine, tyrosine, tryptophan, proline, hydroxyproline, arginine, histidine, lysine, or ornithine. For the purpose of promoting the formation of the imidization compound, a more preferred example of the compound for promoting imidization is N-α-(9-fluorenylmethoxycarbonyl)-N-τ-(tert-butoxycarbonyl)-L-histidine.

[0215] Liquid crystal alignment film and liquid crystal display element

[0216] The liquid crystal alignment film of the present invention is formed by the liquid crystal alignment agent used in the above-mentioned photo-alignment method. The liquid crystal alignment film of the present invention can be used as a liquid crystal alignment film of a horizontal alignment type or a vertical alignment type (VA type), and is suitable for a liquid crystal alignment film of a horizontal alignment type liquid crystal display element such as an IPS mode or a FFS mode. The liquid crystal display element of the present invention comprises the liquid crystal alignment film. The liquid crystal display element of the present invention can be produced, for example, by the method of steps (1) to (4), or by the method of steps (1) to (2) and step (4).

[0217] Step (1): Apply the liquid crystal alignment agent on the substrate

[0218] The liquid crystal alignment agent for the photo-alignment method of the present invention is applied to one side of a substrate provided with a patterned transparent conductive film using an appropriate coating method such as roller coating, spin coating, printing or inkjet coating. The substrate is not particularly limited and only needs to be a highly transparent substrate. A glass substrate or a silicon nitride substrate can also be used in combination with a plastic substrate such as an acrylic substrate or a polycarbonate substrate. Secondly, in a reflective liquid crystal display element, when only a single-sided substrate is used, an opaque material such as a silicon wafer can also be used, and the electrodes used can also be made of a light-reflecting material such as aluminum. Furthermore, when making an IPS-type or FFS-type liquid crystal display element, a comb-tooth type uses an electrode substrate composed of a patterned transparent conductive film or metal film and an opposing substrate without an electrode.

[0219] The method of coating the liquid crystal alignment agent for the photo-alignment method on a substrate to form a film may include screen printing, offset printing, flexographic printing, inkjet printing or spray coating, etc. Preferably, the film forming method is coating using an inkjet method.

[0220] Step (2): calcining the coated liquid crystal alignment agent

[0221] Step (2) is a step of calcining the liquid crystal alignment agent coated on the substrate to form a film. After the liquid crystal alignment agent is coated on the substrate, the solvent can be evaporated by heating means such as a hot plate, a heat circulation oven or an infrared oven, or thermal imidization of polyamic acid or polyamic acid ester can be performed. The drying step and calcination step performed after the liquid crystal alignment agent for the photoalignment method of the present invention has been coated can be selected at any temperature and time, and multiple drying steps or calcination steps can be performed. The temperature of the drying step can be, for example, 40°C to 180°C. Based on the viewpoint of shortening the process, the drying step can be performed at 40°C to 150°C. The time of the drying step is not particularly limited, and it can be, for example, 1 minute to 10 minutes or 1 minute to 5 minutes. When thermal imidization of polyamic acid or polyamic acid ester is performed, after the drying step, a calcination step can be further performed at a temperature of, for example, 150°C to 300°C or 150°C to 250°C. The calcining time is not particularly limited, for example, 5 minutes to 40 minutes or 5 minutes to 30 minutes. If the thickness of the membrane after calcining is too thin, the reliability of the liquid crystal display device will be reduced. Therefore, preferably, the thickness of the membrane is 5nm to 300nm, and more preferably, the thickness of the membrane is 10nm to 200nm.

[0222] Step (3): Orient the film obtained in step (2)

[0223] Step (3) is to perform an alignment treatment on the film obtained in step (2) as appropriate. That is, in a horizontal alignment type liquid crystal display element such as the IPS mode or the FFS mode, the film is subjected to an alignment treatment to impart alignment capability. On the other hand, in a vertical alignment type liquid crystal display element such as the VA mode or the PSA mode, the formed film can be used directly as a liquid crystal alignment film, but the film can also be subjected to an alignment treatment to impart alignment capability. The alignment treatment of the liquid crystal alignment film can include a friction treatment method or a photo-alignment treatment method. Preferably, the alignment treatment of the liquid crystal alignment film is a photo-alignment treatment method. The photo-alignment treatment method can include irradiating the surface of the film with radiation that has been deflected in a certain direction, and, as appropriate, preferably, heating at a temperature of 150°C to 250°C to impart liquid crystal alignment (also called liquid crystal alignment capability). The radiation can use ultraviolet rays or visible light with a wavelength of 100nm to 800nm. Preferably, the radiation is ultraviolet light with a wavelength of 100 nm to 400 nm, and more preferably, the radiation is ultraviolet light with a wavelength of 200 nm to 400 nm.

[0224] The radiation dose can be 1 mJ / cm 2 Up to 10,000mJ / cm 2 Preferably, the radiation dose is 100 mJ / cm 2 Up to 5,000mJ / cm 2 More preferably, the radiation dose is 100 mJ / cm 2 Up to 1500mJ / cm 2 Preferably, the radiation dose is 100 mJ / cm 2 Up to 1000mJ / cm 2 When using a general liquid crystal alignment agent, the light exposure for alignment treatment is 100mJ / cm 2 Up to 5000mJ / cm 2 However, the liquid crystal alignment agent used in the photo-alignment method of the present invention can still form a liquid crystal alignment film in which the variation (non-uniformity) of the liquid crystal alignment within the film surface is effectively suppressed even if the amount of light irradiation during the alignment treatment is reduced. When irradiating the radiation, in order to improve the liquid crystal alignment, the substrate having the film-like material can be heated at 50°C to 250°C while irradiating. The liquid crystal alignment film produced in this way can stably align the liquid crystal molecules in a certain direction. Secondly, the liquid crystal alignment film irradiated with polarized radiation in the above method can be contact-treated with a solvent, or the liquid crystal alignment film irradiated with radiation can be heated.

[0225] The solvent used in the contact treatment is not particularly limited; it only needs to be able to dissolve the decomposition products generated from the film after irradiation. Examples of the solvent 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, or cyclohexyl acetate. Based on versatility and safety, the solvent is preferably water, 2-propanol, 1-methoxy-2-propanol, or ethyl lactate, and more preferably, water, 1-methoxy-2-propanol, or ethyl lactate. The solvents may be used alone or in combination.

[0226] In some embodiments of the present invention, the film irradiated with radiation is preferably heated at a temperature of 50° C. to 300° C., more preferably at a temperature of 120° C. to 250° C. The heating time is preferably 1 minute to 30 minutes.

[0227] Step (4): Making liquid crystal cells

[0228] Two substrates with liquid crystal alignment films formed on their surfaces are prepared, and liquid crystals are placed between the two facing substrates. For example, the following two methods can be used. The first method involves first placing the two substrates face-to-face with their liquid crystal alignment films facing each other, with a gap (cell gap) separating them. The two substrates are then bonded together with a sealant around their perimeters. The liquid crystal composition is then injected into the cell gap defined by the substrate surfaces and the sealant. Once the liquid crystal composition contacts the film surfaces, the injection hole is sealed.

[0229] The second method is called the ODF (One Drop Fill) method. A UV-curable sealant, such as one, is applied to a predetermined position on one of the two substrates having a liquid crystal alignment film formed on its surface. Then, a liquid crystal composition is added dropwise to a plurality of predetermined positions on the surface of the liquid crystal alignment film. The other substrate is then attached with the liquid crystal alignment films facing each other, and the liquid crystal composition is pressed against the entire surface of the liquid crystal alignment film so that it contacts the film surface of the other liquid crystal alignment film. Next, the entire surface of the substrate is irradiated with UV light to cure the sealant. When performing any of the above methods, it is preferred that the liquid crystal composition used is further heated to a temperature at which it becomes isotropic and then slowly cooled to room temperature to remove the flow alignment during liquid crystal filling. Secondly, when the film is subjected to a rubbing treatment, the two substrates are arranged so that the rubbing directions of the films are at predetermined angles to each other, for example, perpendicular or antiparallel. The sealant may be, for example, an epoxy resin containing a hardener and aluminum oxide balls as spacers. The liquid crystal composition is, for example, a nematic liquid crystal or a smectic liquid crystal. Preferably, the liquid crystal composition is a nematic liquid crystal.

[0230] Optionally, a polarizing plate can be attached to the outer surface of the liquid crystal cell to produce a liquid crystal display device. The polarizing plate attached to the outer surface of the liquid crystal cell can be made of, for example, a polarizing film called "H-film" that stretches and aligns polyvinyl alcohol and absorbs iodine. The polarizing plate can be sandwiched between cellulose acetate protective films or comprised solely of the H-film.

[0231] The present invention will be further described with reference to the following examples. However, it should be understood that the examples are only used for illustration and should not be construed as limiting the implementation of the present invention.

[0232] [Preparation Example 1] First Polymer (A1)

[0233] A nitrogen inlet, agitator, condenser tube and thermometer are set on a four-necked conical flask with a capacity of 500 ml, and nitrogen is introduced. Then, 0.035 mole (70 mole %) of compound b1-1-1, 0.01 mole (20 mole %) of compound b1-2-1, 0.005 mole (10 mole %) of compound b1-3-1 and 80 grams of N-methyl-2-pyrrolidone are added, and stirred at room temperature until dissolved. Then, 0.05 mole (100 mole %) of compound a1-1-1 and 20 grams of N-methyl-2-pyrrolidone are added, and reacted at room temperature for 2 hours to obtain a reaction solution. The reaction solution is poured into 1500 ml of water to precipitate a polymer, then, filtered and obtained a filter cake, then, the filter cake is washed with methanol and then filtered, and the filter cake is washed and filtered with methanol, and carried out three times to obtain a crude product. Next, the crude product was placed in a vacuum oven and dried at 60° C. to obtain a first polymer (A1).

[0234] [Preparation Examples 2 to 6] First Polymer (A1)

[0235] Preparation Examples 2 to 6 prepared the first polymer (A1) in a similar manner to Preparation Example 1, except that the types and amounts of the tetracarboxylic dianhydride component (a1) and the diamine component (b1) were changed in Preparation Examples 2 to 6, as shown in Table 1.

[0236] Table 1

[0237]

[0238]

[0239]

[0240] [Preparation Example 7] Second Polymer (A2)

[0241] A nitrogen inlet, a stirrer, a condenser and a thermometer are set on a four-necked conical flask with a capacity of 500 ml, and nitrogen is introduced. Then, 0.05 mol (100 mol%) of compound b2-1-1 and 80 g of N-methyl-2-pyrrolidone are added and stirred at room temperature until dissolved. Then, 0.05 mol (100 mol%) of compound a2-1-1 and 20 g of N-methyl-2-pyrrolidone are added and reacted at room temperature for 2 hours to obtain a reaction solution. The reaction solution is poured into 1500 ml of water to precipitate a polymer, and then filtered to obtain a filter cake. Then, the filter cake is washed with methanol and then filtered. The filter cake is washed and filtered with methanol for a total of three times to obtain a crude product. Then, the crude product is placed in a vacuum oven and dried at a temperature of 60°C to obtain a second polymer (A2).

[0242] [Preparation Examples 8 to 11 and Comparative Preparation Examples 1 to 3] Second Polymer (A2)

[0243] Preparation Examples 8 to 11 and Comparative Preparation Examples 1 to 3 prepared the second polymer (A2) by a method similar to Preparation Example 7, except that: Preparation Examples 8 to 11 and Comparative Preparation Examples 1 to 3 changed the type and amount of the tetracarboxylic dianhydride component (a2) and the diamine component (b2), as shown in Table 2.

[0244] Table 2

[0245]

[0246]

[0247] [Example 1] Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element for optical alignment method

[0248] 90 parts by weight of the first polymer (A1) of Preparation Example 1, 10 parts by weight of the second polymer (A2) of Preparation Example 7 and 1200 parts by weight of N-methyl-2-pyrrolidone [as solvent (B)] are stirred and mixed at room temperature to obtain a liquid crystal alignment agent for photoalignment method.

[0249] The photo-alignment liquid crystal alignment agent was spin-coated onto the pixel electrodes of a glass substrate containing a pair of indium tin oxide (ITO) electrodes (10 μm in width, 10 μm in spacing, and 50 nm in height) for IPS driving. The ITO electrodes were comb-shaped, with the comb-shaped portions spaced and interlocking. The glass substrate coated with the photo-alignment liquid crystal alignment agent was then dried on an 80°C hot plate for 3 minutes. The glass substrate was then baked in a 250°C hot air circulation oven for 30 minutes, forming a 100 nm thick film of the photo-alignment liquid crystal alignment agent on the glass substrate. The film is irradiated with ultraviolet light having a wavelength of 254 nm through a polarizing plate, and then baked in a hot air circulation oven at 250° C. for 30 minutes to form a liquid crystal alignment film on the film, thereby obtaining a first laminate including the liquid crystal alignment film.

[0250] The photo-alignment agent was spin-coated onto a glass substrate lacking pixel electrodes and having columnar spacers 4 μm in height. The glass substrate coated with the photo-alignment agent was then dried on an 80°C hot plate for 3 minutes and then baked in a 250°C hot air circulating oven for 30 minutes to form a 100 nm thick film of the photo-alignment agent on the glass substrate. The film was then irradiated with 254 nm ultraviolet light through a polarizing plate and baked in a 250°C hot air circulating oven for 30 minutes to form a liquid crystal alignment film, thereby obtaining a second laminate comprising the liquid crystal alignment film.

[0251] A sealant was printed on one of the first and second laminates. The liquid crystal alignment film of the first laminate and the liquid crystal alignment film of the second laminate were then laminated together so that they faced each other and had an alignment direction of 0°. The sealant was then cured to obtain a laminate containing an injection port and a liquid crystal cell cavity communicating with the injection port. Subsequently, liquid crystal MLC-2041 (manufactured by Merck) was injected into the liquid crystal cell cavity using a reduced-pressure injection method, and the injection port was sealed to obtain a liquid crystal display device.

[0252] [Examples 2 to 6 and Comparative Examples 1 to 3] Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element for optical alignment method

[0253] Examples 2 to 6 and Comparative Examples 1 to 3 obtain liquid crystal alignment agents, liquid crystal alignment films and liquid crystal display elements for the photo-alignment method using a method similar to that of Example 1. The differences are that Examples 2 to 6 and Comparative Examples 1 to 3 change the types and / or amounts of the first polymer (A1), the second polymer (A2) and the solvent (B) in the liquid crystal alignment agent for the photo-alignment method, as shown in Table 3.

[0254] [Evaluation items]

[0255] The following description takes the liquid crystal display device of Example 1 as an example, and the liquid crystal display devices of other Examples 2 to 6 and Comparative Examples 1 to 3 are prepared in the same manner.

[0256] Flicker after high-voltage driving: The liquid crystal display element of Example 1 was placed between two polarizers with their polarization axes perpendicular to each other. The LED backlight was illuminated with no voltage applied. The angle of the liquid crystal display element of Example 1 was adjusted to minimize the brightness of the light passing through the liquid crystal display element. Next, an AC voltage with a frequency of 30 Hz was applied to the liquid crystal display element of Example 1, and the VT curve (voltage-transmittance curve) was measured. The AC voltage that produces a relative transmittance of 23% was calculated as the driving voltage.

[0257] Next, the liquid crystal display device of Example 1 was kept at a temperature of 23°C. The LED backlight was turned off, and after being shielded from light for 72 hours, the LED backlight was turned on again. Simultaneously with the start of the LED backlight, an AC voltage with a relative transmittance of 100% and a frequency of 30 Hz was applied to the liquid crystal display device of Example 1. The liquid crystal display device of Example 1 was driven for 24 hours. Then, an AC voltage with a relative transmittance of 23% and a frequency of 30 Hz was applied to the liquid crystal display device of Example 1. A data acquisition / data recording switching device 34970A (manufactured by Agilent Technologies) connected to a photodiode and an IV converter amplifier was used to track the flicker amplitude of the liquid crystal display device of Example 1. The brightness values ​​of the liquid crystal display device of Example 1 were read through two polarizing plates. The flicker amplitude and brightness values ​​were used to calculate the flicker degree of the liquid crystal display device of Example 1 according to the following formula.

[0258] Flicker degree (%) = [flicker amplitude / (2×brightness value)]×100%

[0259] The lower the flicker, the better the quality of the liquid crystal display element. The flicker judgment criteria are as follows: ◎ means flicker <3%, ○ means 4% > flicker ≥ 3%, △ means 5% > flicker ≥ 4%, ╳: flicker ≥ 5%.

[0260] Table 3

[0261]

[0262]

[0263] Referring to Table 3, the liquid crystal alignment agents used in the optical alignment method of Examples 1 to 6 are prepared using the first polymer (A1) of Preparation Examples 1 to 6 and the second polymer (A2) of Preparation Examples 7 to 11. In particular, the second polymer (A2) of Preparation Examples 7 to 11 is prepared by the tetracarboxylic dianhydride component (a2) containing the tetracarboxylic dianhydride compound (a2-1) and the diamine component (b2) containing the diamine compound (b2-1). Therefore, the liquid crystal alignment films formed by the liquid crystal alignment agents used in the optical alignment method of Examples 1 to 6 can impart to the liquid crystal display element a flicker after high-voltage driving of less than 4%, indicating that the liquid crystal display elements of Examples 1 to 6 are less likely to flicker after high-voltage driving.

[0264] In contrast, in Comparative Examples 1 to 3, the liquid crystal alignment agents used in the photoalignment method of Comparative Examples 1 to 3 were prepared using the first polymer (A1) of Preparation Examples 1 to 6 and the second polymer (A2) of Comparative Preparation Examples 1 to 3. The tetracarboxylic dianhydride component (a2) used in the second polymer (A2) of Comparative Preparation Example 1 did not contain the tetracarboxylic dianhydride compound (a2-1); the diamine component (b2) used in the second polymer (A2) of Comparative Preparation Example 2 did not contain the diamine compound (b2-1); and the tetracarboxylic dianhydride component (a2) used in the second polymer (A2) of Comparative Preparation Example 3 did not contain the tetracarboxylic dianhydride compound (a2-1), and the diamine component (b2) did not contain the diamine compound (b2-1). Therefore, the flicker degree of the liquid crystal display elements of Comparative Examples 1 to 3 after high-voltage driving was 5% or more, indicating that the liquid crystal display elements of Comparative Examples 1 to 3 easily flickered after high-voltage driving.

[0265] In summary, by using the second polymer (A2) prepared from a polyimide precursor having a structure represented by formula (II), the liquid crystal alignment film formed by the liquid crystal alignment agent used in the photo-alignment method of the present invention can give the liquid crystal display element a low flicker after high-voltage driving. Therefore, the liquid crystal display element comprising the liquid crystal alignment film is not easy to flicker after high-voltage driving, so the purpose of the present invention can indeed be achieved.

[0266] However, the above is merely an embodiment of the present invention and should not be used to limit the scope of the present invention. All simple equivalent changes and modifications made according to the claims and description of the present invention are still within the scope of the present invention.

Claims

1. A liquid crystal alignment agent for a photo-alignment method, characterized in that: The liquid crystal alignment agent used in the photo-alignment method comprises: The polymer component (A) comprises a first polymer (A1) and a second polymer (A2), wherein the first polymer (A1) is at least one selected from the group consisting of a polyimide precursor and an imidized polymer formed from the polyimide precursor, and the second polymer (A2) is at least one selected from the group consisting of a polyimide precursor and an imidized polymer formed from the polyimide precursor; and Solvent (B); The polyimide precursor of the first polymer (A1) comprises a structure represented by formula (I), X 1 represents at least one of the structures represented by formula (I-1) to formula (I-7), "*" represents the bonding position, X 11 、X 12 、X 13 and X 14 each independently represents hydrogen, halogen, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms and containing fluorine, or a phenyl group, X 15 With X 16 Each independently represents hydrogen or methyl, X 2 represents hydrogen or an alkyl group having 1 to 4 carbon atoms, X 3 represents hydrogen or an alkyl group having 1 to 4 carbon atoms, Y 1 represents a divalent organic group; The polyimide precursor of the second polymer (A2) comprises a structure represented by formula (II), V 1 represents the structure shown in formula (II-1), "*" represents the bonding position, V 2 represents hydrogen or an alkyl group having 1 to 4 carbon atoms, V 3 represents hydrogen or an alkyl group having 1 to 4 carbon atoms, W 1 The structure represented by formula (II-2) is represented by In the formula (II-2), R 1 to R 10 At least two of them are "*" representing bonding positions, and the rest are H or monovalent organic groups.

2. The liquid crystal alignment agent for photo-alignment method according to claim 1, characterized in that: The X 1 The structure represented by formula (I-1) is selected from the structures represented by formula (I-1-1) to formula (I-1-6), 3. The liquid crystal alignment agent for photo-alignment method according to claim 1, characterized in that: The X 1 The structure represented by formula (I-1) is the structure represented by formula (I-1-1), 4. The liquid crystal alignment agent for photo-alignment method according to claim 1, characterized in that: The polyimide precursor of the second polymer (A2) is formed by reacting a reaction composition comprising a tetracarboxylic dianhydride component (a2) and a diamine component (b2), wherein the tetracarboxylic dianhydride component (a2) comprises V in the structure represented by the formula (II). 1 The diamine component (b2) comprises W in the structure shown in the formula (II) 1 .

5. A liquid crystal alignment film, characterized in that: The liquid crystal alignment film is formed by the liquid crystal alignment agent for the photo-alignment method according to any one of claims 1 to 4.

6. A liquid crystal display element, characterized in that: The liquid crystal display element comprises the liquid crystal alignment film according to claim 5 .

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