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

Abstract

The invention relates to a liquid crystal alignment agent for a photoalignment method, a liquid crystal photoalignment film and a liquid crystal display element. The present invention relates to a liquid crystal alignment agent for a photo-alignment method having excellent heat resistance, a liquid crystal photo-alignment film formed from the liquid crystal alignment agent, and a liquid crystal display element comprising the liquid crystal photo-alignment film. The liquid crystal alignment agent for the photo-alignment method comprises a polymer component (A), a solvent (B) and a compound (C). The polymer component (A) includes at least one first polymer (A1) selected from the group consisting of a polyimide precursor and an imidized polymer formed by the polyimide precursor. The polyimide precursor of the first polymer (A1) comprises a structure shown in a formula (I), the compound (C) comprises a structure shown in a formula (c-1), and the definitions of the polyimide precursor and the compound (C) are respectively shown in the description and the claims. By using the compound (C), the heat resistance of the liquid crystal display element comprising the liquid crystal photo-alignment film formed by the liquid crystal alignment agent is excellent. (I) (c-1)

Description

Technical Field

[0001] This invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element, and particularly to a liquid crystal alignment agent, a liquid crystal photoalignment film, and a liquid crystal display element for photoalignment with good heat resistance. Background Technology

[0002] Liquid crystal display (LCD) elements are widely used as display components in personal computers, smartphones, mobile phones, and television receivers. An LCD element may include a liquid crystal layer sandwiched between a substrate and a color filter substrate, pixel electrodes and common electrodes that apply an electric field to the liquid crystal layer, a liquid crystal alignment film that controls the alignment of the liquid crystal molecules in the liquid crystal layer, and thin-film transistors (TFTs) that switch the electronic signals supplied to the pixel electrodes. Regarding the driving methods of liquid crystal molecules, known methods include longitudinal electric field methods such as twisted nematic (TN) and vertical alignment (VA), and transverse electric field methods such as in-plane switching (IPS) and fringe field switching (FFS).

[0003] Currently, the most common industrial liquid crystal alignment film is made by rubbing the surface of a film formed on an electrode substrate, consisting of polyamic acid and / or polyimide obtained by imidization, in one direction using a cloth such as cotton, nylon, or polyester. Friction treatment is a simple and highly productive industrial alignment method. However, with the increasing performance, precision, and size of liquid crystal display elements, scratches caused by dust, mechanical force, and static electricity generated during friction treatment on the surface of the liquid crystal alignment film lead to various problems such as alignment inhomogeneity. As an alternative to friction treatment, photoalignment methods are known, which impart alignment capability to the liquid crystal by irradiating it with polarized radiation. Regarding photoalignment methods, Japanese Patent Application Publication No. Hei 9-297313 discloses methods utilizing photoisomerization reactions, photocrosslinking reactions, or photodecomposition reactions.

[0004] However, liquid crystal display elements containing existing liquid crystal alignment films prepared by photoalignment methods are prone to poor heat resistance and cannot meet application requirements. Summary of the Invention

[0005] The first objective of this invention is to provide a liquid crystal alignment agent for photoalignment that can impart good heat resistance to liquid crystal display elements.

[0006] The liquid crystal alignment agent used in the photoalignment method of the present invention comprises a polymer component (A), a solvent (B), and a compound (C).

[0007] The polymer component (A) includes a first polymer (A1), and 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.

[0008] The polyimide precursor of the first polymer (A1) comprises a structure as shown in formula (I).

[0009] (I)

[0010] In equation (I), X 1 This indicates at least one of the groups consisting of structures as shown in equations (I-1) to (I-7). "Indicates the location of the bond,

[0011] (I-1) (I-2) (I-3) (I-4) (I-5) (I-6) (I-7),

[0012] In the above formula (I-1), X 11 X 12 X 13 and X 14 Each of these can independently represent hydrogen, halogen, alkyl with 1 to 6 carbon atoms, alkenyl with 2 to 6 carbon atoms, alkynyl with 2 to 6 carbon atoms, monovalent organic group with 1 to 6 carbon atoms containing fluorine, or phenyl.

[0013] In the above formula (I-7), X 15 With X 16 Each can be used independently to represent hydrogen or methyl.

[0014] X 2 Indicates an alkyl group having 1 to 4 carbon atoms.

[0015] X 3 Indicates an alkyl group having 1 to 4 carbon atoms.

[0016] Y 1 It represents a divalent organic group.

[0017] The compound (C) comprises the structure shown in formula (c-1).

[0018] (c-1)

[0019] In the above equation (c-1), R 1 This indicates an n-valent organic group containing an aliphatic or aromatic hydrocarbon group with 1 to 20 carbon atoms.

[0020] n represents an integer from 2 to 6.

[0021] R 2 The R indicates an alkyl group, an alkenyl group, or an alkynyl group having 5 to 20 carbon atoms. 2 It may have substituents selected from at least one of methoxy, ethoxy, halogen, hydroxy, phenyl and tolyl, and the substituents contain at least one hydroxyl group.

[0022] In the liquid crystal alignment agent used in the photoalignment method of the present invention, the compound (C) is selected from at least one of compounds having the structure shown in formula (c-1-1) and compounds having the structure shown in formula (c-1-2).

[0023] (c-1-1)

[0024] In the above formula (c-1-1),

[0025] R 3 R 4 R 5 Each of the above independently represents an alkyl group, an alkenyl group, or an alkynyl group having 1 to 20 carbon atoms, and the R group... 3 The R 4 The R 5 It may have substituents, said substituents being selected from at least one of methoxy, ethoxy, halogen, hydroxy, phenyl, and tolyl, and said R 3 The substituents of R contain at least one hydroxyl group. 3 The R 4 The R 5 The total number of carbon atoms is 4 or more.

[0026] R 6 This indicates an m-valent organic group containing an aliphatic or aromatic hydrocarbon group with 1 to 20 carbon atoms, where m represents an integer from 2 to 6.

[0027] (c-1-2)

[0028] In the above formula (c-1-2),

[0029] R 7 R 8 R 9Each of the above independently represents an alkyl group, an alkenyl group, or an alkynyl group having 1 to 20 carbon atoms, and the R group... 7 The R 8 The R 9 It may have substituents, said substituents being selected from at least one of methoxy, ethoxy, halogen, hydroxy, phenyl, and tolyl, and said R 7 The substituents of R contain at least one hydroxyl group. 7 The R 8 The R 9 The total number of carbon atoms is 3 or more.

[0030] R 10 It represents a p-valent organic group containing an aliphatic or aromatic hydrocarbon group with 1 to 20 carbon atoms, where p represents an integer from 2 to 6.

[0031] In the liquid crystal alignment agent used in the photoalignment method of the present invention, the R in formula (c-1-1) 4 The substituents contain at least one hydroxyl group.

[0032] In the liquid crystal alignment agent used in the photoalignment method of the present invention, the R in formula (c-1-2) 8 The substituents contain at least one hydroxyl group.

[0033] In the liquid crystal alignment agent used in the photoalignment method of the present invention, the total amount of the polymer component (A) used is 100 parts by weight, and the amount of the compound (C) used ranges from 0.5 parts by weight to 20 parts by weight.

[0034] In the liquid crystal alignment agent used in the photoalignment method described in this invention, the X 1 It is selected from the structures shown in equations (I-1-1) to (I-1-6).

[0035] (I-1-1) (I-1-2) (I-1-3) (I-1-4) (I-1-5) (I-1-6).

[0036] In the liquid crystal alignment agent used in the photoalignment method described in this invention, the X 1 The structure is as shown in equation (I-1-1).

[0037] (I-1-1).

[0038] In the liquid crystal alignment agent for the photoalignment method of the present invention, the polymer component (A) further includes a second polymer (A2), 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. 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). The diamine component (b2) includes a diamine compound (b2-1) having a nitrogen-containing structure, and the nitrogen atom structure in the diamine compound (b2-1) is selected from at least one of the group consisting of nitrogen-containing heterocycles, secondary amino groups, and tertiary amino groups.

[0039] The second objective of this invention is to provide a liquid crystal photoalignment film that imparts good heat resistance to liquid crystal display elements.

[0040] The liquid crystal photoalignment film of the present invention is formed from a liquid crystal alignment agent used in the photoalignment method as described above.

[0041] A third objective of this invention is to provide a liquid crystal display element with excellent heat resistance.

[0042] The liquid crystal display element of the present invention includes a liquid crystal photoalignment film as described above.

[0043] The beneficial effect of the present invention is that the liquid crystal alignment agent used in the photoalignment method, by using the compound (C), can impart good heat resistance to the liquid crystal display element containing the liquid crystal photoalignment film formed by the liquid crystal alignment agent used in the photoalignment method. Detailed Implementation

[0044] The present invention provides a liquid crystal alignment agent for photoalignment, comprising: a polymer component (A), a solvent (B), and a compound (C).

[0045] Polymer Component (A)

[0046] The polymer component (A) includes a first polymer (A1).

[0047] <First Polymer (A1)>

[0048] 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. The polyimide precursor of the first polymer (A1) comprises a structure as shown in formula (I).

[0049] (I)

[0050] In equation (I), X 1This indicates at least one of the groups consisting of structures as shown in equations (I-1) to (I-7). " indicates the location of the bond; X" 2 Indicates a hydrogen or alkyl group having 1 to 4 carbon atoms; X 3 Y represents an alkyl group with 1 to 4 carbon atoms; 1 It represents a divalent organic group.

[0051] (I-1) (I-2) (I-3) (I-4) (I-5) (I-6) (I-7)

[0052] In the above formula (I-1), X 11 X 12 X 13 and X 14 Each of these can be independently represented as hydrogen, halogen, alkyl with 1 to 6 carbon atoms, alkenyl with 2 to 6 carbon atoms, alkynyl with 2 to 6 carbon atoms, monovalent organic group with 1 to 6 carbon atoms containing fluorine, or phenyl.

[0053] In the above formula (I-7), X 15 With X 16 Each can be used independently to represent hydrogen or methyl.

[0054] In some embodiments of the present invention, the first polymer (A1) is selected from at least one of the group consisting of a polyimide precursor formed by reacting a reaction composition comprising a tetracarboxylic dianhydride component (a1) and a diamine component (b1) and an imidized polymer formed from the polyimide precursor. For example, the first polymer (A1) is a polyimide precursor having an imide precursor structure of polyamic acid and polyamic ester, or the first polymer (A1) is an imidized polymer (i.e., a polyimide) formed from the polyimide precursor, or the first polymer (A1) comprises the polyimide precursor and the imidized polymer.

[0055] [Tetracarboxylic acid dianhydride component (a1)]

[0056] The tetracarboxylic dianhydride component (a1) can be a tetracarboxylic dianhydride compound, or a tetracarboxylic dianhydride derivative such as a tetracarboxylic dihalide, a tetracarboxylic dialkyl ester, or a tetracarboxylic dialkyl ester dihalide. The tetracarboxylic dianhydride component (a1) can be a single tetracarboxylic dianhydride compound or its derivative, or a combination of multiple compounds.

[0057] [Alicyclic tetracarboxylic dianhydride compound (a1-1)]

[0058] In some embodiments of the present invention, the tetracarboxylic dianhydride component (a1) comprises an alicyclic tetracarboxylic dianhydride compound (a1-1) or a derivative thereof as shown in formula (A11).

[0059] (A11)

[0060] The alicyclic tetracarboxylic dianhydride compound (a1-1) or its derivatives represented by formula (A11) can be composed of a single tetracarboxylic dianhydride or its derivative, or can be composed of multiple tetracarboxylic dianhydrides or their derivatives. The alicyclic tetracarboxylic dianhydride compound (a1-1) represented by formula (A11) is, for example, an acid dianhydride obtained by intramolecularly dehydrating four carboxyl groups, including at least one carboxyl group bonded to an alicyclic structure. However, none of these four carboxyl groups are bonded to an aromatic ring. Alternatively, it may not be necessary to consist solely of an alicyclic structure; a portion of it may also have a chain hydrocarbon structure or an aromatic ring structure. Aromatic tetracarboxylic dianhydrides are, for example, acid dianhydrides obtained by intramolecularly dehydrating four carboxyl groups, including at least one carboxyl group bonded to an aromatic ring. However, aromatic tetracarboxylic dianhydrides do not need to consist solely of an aromatic ring structure; a portion of it may also have a chain hydrocarbon structure or an alicyclic structure. Acyclic alicyclic tetracarboxylic dianhydrides can be, for example, acid dianhydrides obtained by intramolecularly dehydrating four carboxyl groups bonded to a chain hydrocarbon structure. However, acyclic aliphatic tetracarboxylic dianhydrides do not necessarily have to be composed solely of chain hydrocarbon structures; a portion of them may also have alicyclic or aromatic ring structures.

[0061] In the aforementioned formula (A11), X 1 Selected from at least one of the structures shown in equations (I-1) to (I-7), and " " " represents the location of the bond.

[0062] (I-1) (I-2) (I-3) (I-4) (I-5) (I-6) (I-7)

[0063] In the above formula (I-1), X 11 X 12 X 13 With X 14 Each of the following can independently represent hydrogen, halogen, alkyl group having 1 to 6 carbon atoms, alkenyl group having 2 to 6 carbon atoms, alkynyl group having 2 to 6 carbon atoms, monovalent organic group having 1 to 6 carbon atoms and containing a fluorine atom, or phenyl. In the formulas (I-7), X15 With X 16 Each can be used independently to represent hydrogen or methyl.

[0064] In some embodiments of the present invention, in formula (A11), X 1 The structure shown in formula (I-1) is selected from the structures shown in formulas (I-1-1) to (I-1-6).

[0065] (I-1-1) (I-1-2) (I-1-3) (I-1-4) (I-1-5) (I-1-6)

[0066] In some embodiments of the present invention, preferably, in formula (A11), the X 1 The structure shown in equation (I-1) is the structure shown in equation (I-1-1). When the X 1 The structure shown in formula (I-1) is the same as the structure shown in formula (I-1-1). The liquid crystal display element containing the liquid crystal photoalignment film formed by the liquid crystal alignment agent used in the photoalignment method has good heat resistance.

[0067] When the tetracarboxylic dianhydride component (a1) does not contain the alicyclic tetracarboxylic dianhydride compound (a1-1), the liquid crystal display element containing the liquid crystal photoalignment film formed by the liquid crystal alignment agent used in the photoalignment method is prone to poor heat resistance.

[0068] [Other tetracarboxylic acid dianhydride compounds (a1-2)]

[0069] In some embodiments of the present invention, the tetracarboxylic dianhydride component (a1) further comprises other tetracarboxylic dianhydride compounds (a1-2).

[0070] In some embodiments of the present invention, the other tetracarboxylic dianhydride compounds (a1-2) comprise a tetracarboxylic dianhydride compound or a derivative thereof as shown in formula (A12).

[0071] (A12)

[0072] In the aforementioned formula (A12), X 1' This represents the structure shown in equations (A12-1) to (A12-32), " " represents the location of the bond.

[0073] (A12-1) (A12-2)、

[0074] (A12-3)、 (A12-4)、

[0075] (A12-5)、

[0076] (A12-6)、

[0077] (A12-7)、 (A12-8)、

[0078] (A12-9)、 (A12-10)、

[0079] (A12-11)、

[0080] (A12-12)、

[0081] (A12-13)、

[0082] (A12-14)、 (A12-15)、

[0083] (A12-16)、 (A12-17)

[0084] (A12-18)、 (A12-19)、

[0085] (A12-20)、 (A12-21)、

[0086] (A12-22)、 (A12-23)、

[0087] (A12-24)、 (A12-25)、

[0088] (A12-26)、 (A12-27)

[0089] (A12-28) (A12-29)

[0090] (A12-30) (A12-31)

[0091] (A12-32)

[0092] In equation (A12-1), a1 is 1 to 12. In equation (A12-5), X... 11' The group represents a single bond, -O-, -CO-, -COO-, phenylene, sulfonyl, or amide group, and a1 represents 0 or 1. In the formula (A12-6), X 11' and X 12' Each of the following groups independently represents a single bond, -O-, -CO-, -COO-, phenylene, sulfonyl, or amide group, and multiple X groups... 12' The values ​​are either the same or different, and a1 represents 0 or 1. In equation (A12-11), a1 represents 2 to 6. In equation (A12-13), a1 represents 1 to 2. In equation (A12-14), X 13' Each of the following can independently represent hydrogen, halogen, alkyl group having 1 to 6 carbon atoms, alkenyl group having 2 to 6 carbon atoms, alkynyl group having 2 to 6 carbon atoms, monovalent organic group containing fluorine and having 1 to 6 carbon atoms, or phenyl group, and multiple X groups. 13' They can be the same or different. From the viewpoint of liquid crystal alignment, preferably, the X... 13' Each of the following can be independently represented as hydrogen, halogen, methyl, or ethyl; more preferably, X... 13' Each can be used independently to represent hydrogen or methyl.

[0093] In some embodiments of the present invention, formulas (A12-5) and (A12-6) include, but are not limited to, […]. , , , , , , , , , , , , , , , .

[0094] The other tetracarboxylic dianhydride compounds (a1-2) may be used alone or in combination. In some embodiments of the present invention, based on a total usage of 100 moles of the tetracarboxylic dianhydride component (a1), the usage of the other tetracarboxylic dianhydride compounds (a1-2) is from 0 to 70 moles; preferably, the usage of the other tetracarboxylic dianhydride compounds (a1-2) is from 0 to 60 moles; more preferably, the usage of the other tetracarboxylic dianhydride compounds (a1-2) is from 0 to 50 moles.

[0095] [Diamine component (b1)]

[0096] In some embodiments of the present invention, the diamine component (b1) comprises a diamine compound (b1-1).

[0097] [Diamine compound (b1-1)]

[0098] The diamine compound (b1-1) is a diamine compound as shown in formulas (A21-1) to (A21-2).

[0099] (A21-1)

[0100] (A21-2)

[0101] In the aforementioned formula (A21-1), Y 21 This represents a divalent organic group as shown in formula (A21-3), and multiple Y... 22 Each of the following independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. In the formula (A21-2), multiple Y atoms... 23 Each of these represents a divalent organic group as shown in formula (A21-3').

[0102] (A21-3)

[0103] (A21-3')

[0104] In the divalent organic groups shown in 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 by a monovalent substituent or remain unsubstituted; Y 21' Representative - (CH2) n -, where n represents an integer from 2 to 18, and -(CH2) n At least one of the -CH2- in - can be replaced by -O-, -C(=O)-, or -OC(=O)- or not replaced; p1 represents 0 or 1; " " represents the location of the bond.

[0105] In the divalent organic groups represented by formula (A21-3'), Ar' independently represents a divalent benzene ring or biphenyl structure, and the hydrogen atoms of the benzene ring or biphenyl structure can be substituted by monovalent substituents or remain unsubstituted; Y 23' Representative - (CH2) n -, where n represents an integer from 2 to 18, and -(CH2) n At least one of the -CH2- in - can be replaced by -O-, -C(=O)-, or -OC(=O)- or not replaced; p2 represents 0 or 1; " " represents the location of the bond.

[0106] In the divalent organic groups shown in formula (A21-3) and the divalent organic groups shown in formula (A21-3'), the monovalent substituents of the benzene ring, biphenyl structure, or naphthyl ring are, for example, halogens, alkyl groups having 1 to 10 carbon atoms, alkenyl groups having 2 to 10 carbon atoms, alkoxy groups having 1 to 10 carbon atoms, fluoroalkyl groups having 1 to 10 carbon atoms, fluoroalkenyl groups having 2 to 10 carbon atoms, fluoroalkoxy groups having 1 to 10 carbon atoms, carboxyl groups, hydroxyl groups, alkoxycarbonyl groups having 1 to 10 carbon atoms, cyano groups, or nitro groups, etc.

[0107] In some embodiments of the present invention, from the viewpoint of improving liquid crystal alignment, it is preferable that the divalent organic group represented by formula (A21-3) is at least one of the groups represented by formulas (A21-3-1) to (A21-3-16). " " represents the location of the bond.

[0108] (A21-3-1)

[0109] (A21-3-2)

[0110] (A21-3-3)

[0111] (A21-3-4)

[0112] (A21-3-5)

[0113] (A21-3-6)

[0114] (A21-3-7)

[0115] (A21-3-8)

[0116] (A21-3-9)

[0117] (A21-3-10)

[0118] (A21-3-11)

[0119] (A21-3-12)

[0120] (A21-3-13)

[0121] (A21-3-14)

[0122] (A21-3-15) (A21-3-16)

[0123] In equation (A21-3-1), m is 0 to 1, and n is 1 to 6. In equation (A21-3-2), n is 1 to 6. In equation (A21-3-3), n is 2 to 6. In equation (A21-3-4), n is 1 to 6. In equation (A21-3-5), n is 1 to 6. In equation (A21-3-6), n is 2 to 6. In equation (A21-3-7), n is 1 to 6. In equation (A21-3-8), n is 1 to 6. In equation (A21-3-9), n is 2 to 6. In equation (A21-3-10), m is 1 to 3, and n is 1 to 4. In equation (A21-3-11), n ​​is 1 to 6. In equation (A21-3-12), n is 1 to 6. In equation (A21-3-13), m is 0 to 1, and n is 1 to 6. In equation (A21-3-14), m is 1 to 3, and n is 1 to 4.

[0124] In some embodiments of the present invention, from the viewpoint of improving liquid crystal alignment, it is preferred that the divalent organic group represented by formula (A21-3') is a group represented by formula (A21-3-7) to (A21-3-16).

[0125] In some embodiments of the present invention, 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 represented by formulas (A21-3-1) to (A21-3-14) and Y in formula (A21-1) 21 The combination of diamine compounds represented by formulas (A21-3-15) to (A21-3-16).

[0126] 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 formulas (A21-2-1) to (A21-2-5).

[0127] (A21-2-1)

[0128] (A21-2-2)

[0129] (A21-2-3)

[0130] (A21-2-4)

[0131] (A21-2-5)

[0132] In equation (A21-2-1), m is 1 to 6, and n is 1 to 6. In equation (A21-2-2), m is 1 to 6, and n is 1 to 6. In equation (A21-2-3), m is 2 to 6, and n is 2 to 6.

[0133] The diamine compound (b1-1) can be used alone or in combination. In some embodiments of the invention, based on a total usage of 100 moles of the diamine component (b1), the usage of the diamine compound (b1-1) is 20 to 90 moles; preferably, the usage of the diamine compound (b1-1) is 25 to 80 moles; more preferably, the usage of the diamine compound (b1-1) is 30 to 70 moles.

[0134] [Diamine compounds having a -N(D)- group (b1-2)]

[0135] In some embodiments of the present invention, the diamine component (b1) further comprises diamine compounds (b1-2) having a -N(D)- group.

[0136] From the viewpoint of improving the voltage retention rate of liquid crystal display elements, the molecular structure of the first polymer (A1) may selectively have a -N(D)- group (D represents a urethane protecting group). The first polymer (A1) having a -N(D)- group can be obtained by using a monomer having a -N(D)- group as at least a portion of the reactants, or by using a monomer having a -N(D)- group as a capping agent as described below. In some specific examples, the monomer having a -N(D)- group is, for example, a diamine compound (b1-2) having a -N(D)- group. For example, the urethane protecting group is, for example, but not limited to, tert-butoxycarbonyl (Boc) or 9-fluorenylmethoxycarbonyl.

[0137] In some embodiments of the invention, preferably, the diamine compound (b1-2) having the -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 the -N(D)- group comprises a diamine compound having at least one aromatic group and having 6 to 30 carbon atoms in residues other than the substituent (D). In some specific examples of the invention, the diamine compound (b1-2) having the -N(D)- group is, for example, but not limited to, diamine compounds represented by formulas (A22-1) to (A22-11).

[0138] (A22-1)

[0139] (A22-2) (A22-3)

[0140] (A22-4)

[0141] (A22-5) (A22-6)

[0142] (A22-7)

[0143] (A22-8)

[0144] (A22-9)

[0145] (A22-10) (A22-11)

[0146] In equation (A22-1), n ​​is 1 to 6. In equation (A22-2), n is 1 to 6. In equation (A22-4), m is 1 to 6, and n is 1 to 6. In equation (A22-7), m is 1 to 6, and n is 1 to 6. In equation (A22-9), n is 1 to 6. In equation (A22-11), n ​​is 1 to 6.

[0147] The diamine compound (b1-2) having the -N(D)- group can be used alone or in combination. In some embodiments of the invention, based on a total usage of 100 moles of the diamine component (b1), the usage of the diamine compound (b1-2) having the -N(D)- group is 2 to 60 moles; preferably, the usage of the diamine compound (b1-2) having the -N(D)- group is 10 to 50 moles; more preferably, the usage of the diamine compound (b1-2) having the -N(D)- group is 15 to 40 moles.

[0148] [Other diamine compounds (b1-3)]

[0149] In some embodiments of the present invention, the diamine component (b1) further comprises other diamine compounds (b1-3).

[0150] The other diamine compounds (b1-3) include, but are not limited to, diamine compounds having photoalignment groups, 4-amino-N-methylphenethylamine, 4-aminophenethylamine, 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol, diamine compounds having carboxyl groups, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, etc. Aminodiphenyl ketone, 1,4-bis(4-aminobenzyl)benzene, 4,4'-diaminodiphenyl ether, 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, diamine compounds with urea bonds, diamine compounds with amide bonds, diamine compounds with photopolymerizable groups at the ends, diamine compounds with siloxane bonds, or diamine compounds with oxazoline structures, etc.

[0151] The diamine compounds having photoalignment groups are, for example, but not limited to, 4,4'-diaminoazobenzene, or diamine compounds as shown in formulas (A23-1) to (A23-3).

[0152] (A23-1)

[0153] (A23-2)

[0154] (A23-3)

[0155] The diamine compounds having a carboxyl group are, for example but not limited to, 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, 3,5-diaminobenzoic acid, or diamine compounds as shown in formulas (A23-4) to (A23-7).

[0156] (A23-4)

[0157] (A23-5)

[0158] (A23-6)

[0159] (A23-7)

[0160] In the aforementioned formula (A23-4), Y 31 The following represent single bonds: -CH2-, -C2H4-, -C(CH3)2-, -CF2-, -C(CF3)2-, -O-, -CO-, -NH-, -N(CH3)-, -CONH-, -NHCO-, -CH2O-, -OCH2-, -COO-, -OCO-, -CON(CH3)-, or -N(CH3)CO-; m1 and m2 each independently represent integers from 0 to 4, and (m1+m2) represents integers from 1 to 4. In equation (A23-5), m3 and m4 each independently represent integers from 1 to 5. In equation (A23-6), Y 32 m5 represents a straight-chain 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 of these can be represented independently as 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.

[0161] The diamine compounds having urea bonds are, for example, but not limited to, the diamine compounds shown in formulas (A23-8) to (A23-10).

[0162] (A23-8)

[0163] (A23-9)

[0164] (A23-10)

[0165] In equation (A23-8), n1 is 0 to 6, and n2 is 1 to 6. In equation (A23-9), n1 is 1 to 6, and n2 is 1 to 6. In equation (A23-10), n is 1 to 6.

[0166] The diamine compounds having amide bonds are, for example, but not limited to, the diamine compounds having amide bonds shown in formulas (A23-11) to (A23-13).

[0167] (A23-11)

[0168] (A23-12)

[0169] (A23-13)

[0170] In equation (A23-12), n is 1 to 6. In equation (A23-13), n1 is 1 to 6, and n2 is 1 to 6.

[0171] The diamine compound having a photopolymerizable group at the end is, for example, but not limited to, 2-(2,4-diaminophenoxy)ethyl methacrylate or 2,4-diamino-N,N-diallyl aniline.

[0172] The diamine compounds having siloxane bonds are, for example, but not limited to, 3-bis(3-aminopropyl)-tetramethyldisiloxane.

[0173] The diamine compounds having an oxazoline structure are, for example, but not limited to, diamine compounds as shown in formulas (A23-14) to (A23-15).

[0174] (A23-14)

[0175] (A23-15)

[0176] The other diamine compounds (b1-3) may be used alone or in combination. In some embodiments of the invention, based on a total usage of 100 moles of the diamine component (b1), the usage of the other diamine compounds (b1-3) is from 0 to 65 moles; preferably, the usage of the other diamine compounds (b1-3) is from 0 to 50 moles; more preferably, the usage of the other diamine compounds (b1-3) is from 0 to 35 moles.

[0177] <Second Polymer (A2)>

[0178] In some embodiments of the present invention, the polymer component (A) further includes a second polymer (A2).

[0179] The second polymer (A2) is selected from at least one of the group consisting of a polyimide precursor formed by reacting a reaction composition comprising a tetracarboxylic dianhydride component (a2) and a diamine component (b2) and an imidized polymer formed from the polyimide precursor, and the second polymer (A2) does not contain the structure shown in formula (I) of the first polymer (A1). For example, the second polymer (A2) is a polyimide precursor having an imide precursor structure of polyamic acid and polyamic ester, or the second polymer (A2) is an imidized polymer (i.e., a polyimide) formed from the polyimide precursor, or the second polymer (A2) comprises the polyimide precursor and the imidized polymer, etc. The second polymer (A2) can be used alone or in combination with other polymers.

[0180] In some embodiments of the present invention, the weight ratio of the first polymer (A1) to the second polymer (A2) [i.e., the mass ratio of the first polymer (A1) to the second polymer (A2)] is 10 / 90 to 90 / 10; preferably, the weight ratio of the first polymer (A1) to the second polymer (A2) is 20 / 80 to 90 / 10; more preferably, the weight ratio of the first polymer (A1) to the second polymer (A2) is 20 / 80 to 80 / 20.

[0181] [Tetracarboxylic acid dianhydride component (a2)]

[0182] The tetracarboxylic dianhydride component (a2) is, for example, but not limited to, acyclic aliphatic tetracarboxylic dianhydride compounds, alicyclic tetracarboxylic dianhydride compounds, aromatic tetracarboxylic dianhydride compounds, or derivatives of these compounds. The acyclic aliphatic tetracarboxylic dianhydride compounds, the alicyclic tetracarboxylic dianhydride compounds, and the aromatic tetracarboxylic dianhydride compounds are, for example, tetracarboxylic dianhydride compounds in the first polymer (A1). Preferably, the tetracarboxylic dianhydride component (a2) comprises an alicyclic tetracarboxylic dianhydride or a derivative thereof as shown in formula (A11), or as shown in formula (A12) above and X 1' Tetracarboxylic dianhydride compounds or derivatives thereof with structures represented by formulas (A12-1) to (A12-6). The tetracarboxylic dianhydride component (a2) may be used alone or in combination.

[0183] In some embodiments of the present invention, preferably, the tetracarboxylic acid dianhydride component (a2) comprises the components shown in formula (A12) and X 1' It is a tetracarboxylic acid dianhydride compound (a2-1) with the structure shown in formula (II).

[0184] (A12)

[0185] (II)

[0186] In equation (II), Z 11 Indicates a single bond, and " "Represents the location of the bond."

[0187] The tetracarboxylic acid dianhydride compound (a2-1) can be used alone or in combination.

[0188] In some embodiments of the present invention, more preferably, the tetracarboxylic dianhydride component (a2) comprises the tetracarboxylic dianhydride compound represented by formula (III).

[0189] (III)

[0190] In some embodiments of the present invention, based on a total usage of 100 moles of the tetracarboxylic dianhydride component (a2), the usage of the tetracarboxylic dianhydride compound (a2-1) is 30 to 100 moles; preferably, the usage of the tetracarboxylic dianhydride compound (a2-1) is 40 to 100 moles; more preferably, the usage of the tetracarboxylic dianhydride compound (a2-1) is 50 to 100 moles.

[0191] [Diamine component (b2)]

[0192] The diamine component (b2) is, for example, but not limited to, the diamine component (b1) of the first polymer (A1), or a diamine compound (b2-1) having a nitrogen-containing structure. The diamine component (b2) may be used alone or in combination.

[0193] [Diamine compounds containing nitrogen atoms (b2-1)]

[0194] The nitrogen-containing structure of the diamine compound (b2-1) having a nitrogen-containing structure is selected from at least one of the group consisting of nitrogen-containing heterocycles, secondary amino groups, and tertiary amino groups.

[0195] The nitrogen-containing heterocycle of the diamine compound (b2-1) having a nitrogen-containing atom structure is, for example, but not limited to, pyrrole, imidazole, pyrazole, triazole, pyridine, pyrimidine, darazine, pyrazine, indole, benzimidazole, purine, quinoline, isoquinoline, nicotinic acid, quinoline, terazine, triazine, carbazole, acridine, piperidine, piperazine, pyrrolidine, or hexamethyleneimine, etc. Preferably, the nitrogen-containing heterocycle is pyridine, pyrimidine, pyrazine, piperidine, piperazine, quinoline, carbazole, or acridine.

[0196] The nitrogen-containing structure of the diamine compound (b2-1) having a nitrogen-containing atom structure is a secondary amino and a tertiary amino as shown in formula (B21).

[0197] (B21)

[0198] In formula (B21), Z represents hydrogen, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, or an aryl group; "Represents the location of the bond."

[0199] The alkyl group having 1 to 10 carbon atoms is, for example, but not limited to, methyl, ethyl, or propyl. The cycloalkyl group is, for example, but not limited to, cyclohexyl. The aryl group is, for example, but not limited to, phenyl or tolyl. Preferably, Z is hydrogen or methyl.

[0200] The diamine compound having a nitrogen-containing structure (b2-1) 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 of formulas (B21-1) to (B21-8), or diamine compounds of formulas (B21-9) to (B21-26).

[0201] (B21-1)

[0202] (B21-2)

[0203] (B21-3)

[0204] (B21-4)

[0205] (B21-5)

[0206] (B21-6)

[0207] (B21-7)、

[0208] (B21-8)、

[0209] (B21-9)、

[0210] (B21-10)、

[0211] (B21-11)、

[0212] (B21-12)、

[0213] (B21-13)、

[0214] (B21-14)、

[0215] (B21-15)、

[0216] (B21-16)、

[0217] (B21-17)、

[0218] (B21-18)、

[0219] (B21-19)、

[0220] (B21-20)、

[0221] (B21-21)、

[0222] (B21-22)、

[0223] (B21-23)、

[0224] (B21-24)、

[0225] (B21-25)、

[0226] (B21-26)

[0227] In formula (B21-5), n represents 1 to 4. In formula (B21-6), n represents 1 to 4. The diamine compound (b2-1) having a nitrogen-containing structure can be used alone or in combination.

[0228] In some embodiments of the present invention, based on a total usage of 100 moles of the diamine component (b2), the usage of the diamine compound (b2-1) having a nitrogen-containing structure is from 15 moles to 100 moles; preferably, the usage of the diamine compound (b2-1) having a nitrogen-containing structure is from 20 moles to 90 moles; more preferably, the usage of the diamine compound (b2-1) having a nitrogen-containing structure is from 25 moles to 80 moles.

[0229] Preparation methods of the first polymer (A1) and the second polymer (A2)

[0230] The first polymer (A1) and the second polymer (A2) can be manufactured by reacting the diamine component and the tetracarboxylic dianhydride component described above in a solvent (condensation polymerization). When a portion of the first polymer (A1) and the second polymer (A2) has an amide acid structure, for example, by reacting the tetracarboxylic dianhydride component with the diamine component, a polymer with an amide acid structure (i.e., polyamic acid) can be obtained. The solvent is not particularly limited, as long as it can dissolve the formed polymer. For example, the solvent is, but is 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-imidazolidineone. In some embodiments of the present invention, when the solvent solubility of the polymer is high, the solvent is, for example, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or solvents as shown in formulas (D-1) to (D-3).

[0231] (D-1)

[0232] (D-2)

[0233] (D-3)

[0234] In the aforementioned equation (D-1), Z 1 This indicates an alkyl group having 1 to 3 carbon atoms. In formula (D-2), Z 2 This indicates an alkyl group having 1 to 3 carbon atoms. In formula (D-3), Z 3 This refers to alkyl groups having 1 to 4 carbon atoms.

[0235] The solvent can be used alone or in combination. Furthermore, even solvents that cannot dissolve the polymer can be mixed with the aforementioned solvents within a range that will not cause the resulting polymer to precipitate. When the diamine component and the tetracarboxylic dianhydride component react in the solvent, the reaction can proceed at any concentration. Preferably, the total concentration of the diamine component and the tetracarboxylic dianhydride component in the reaction is 1 wt% to 50 wt%; more preferably, the total concentration of the diamine component and the tetracarboxylic dianhydride component in the reaction is 5 wt% to 30 wt%. The reaction can also be initially carried out at a high concentration, and then additional solvent can be added. During the reaction, 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 larger the molecular weight of the first polymer (A1) or the second polymer (A2) formed.

[0236] The polymer having an amide ester structure can be obtained, for example, by existing methods, and the existing methods are (1) reacting the polyamic acid obtained by the above methods with an esterifying agent, (2) reacting a tetracarboxylic acid diester compound with a diamine compound, or (3) reacting a tetracarboxylic acid diester dihalide with a diamine compound.

[0237] The imidized polymer in the first polymer (A1) or the second polymer (A2) of the liquid crystal alignment agent used in the photoalignment method of the present invention can be obtained, for example, by cyclizing the polymer having an amide ester structure. In the imidized polymer, the cyclization rate (also called the imidization rate) of the functional groups of the amide acid group or its derivatives is not necessarily 100%, and the imidization rate of the imidized polymer can be adjusted arbitrarily according to the application and / or purpose.

[0238] Methods for obtaining the imidized polymer include, for example, thermal imidization by directly heating a solution containing a polymer having an ammonium ester structure, or catalytic imidization by adding a catalyst to the solution. When thermal imidization is performed in the solution, preferably, the temperature is between 100°C and 400°C; more preferably, the temperature is between 120°C and 250°C. Preferably, during thermal imidization, water generated by the imidization reaction is also removed from the system.

[0239] The catalytic imidization is carried out, for example, by adding a basic catalyst and an acid anhydride to a solution containing the polymer having an ammonium ester structure, preferably with stirring at -20°C to 250°C; more preferably, at 0°C to 180°C. Preferably, the amount of the basic catalyst added is 0.5 to 30 times the molar equivalent of the ammonium acid group; more preferably, the amount of the basic catalyst added is 2 to 20 times the molar equivalent of the ammonium acid group. Preferably, the amount of the acid anhydride added is 1 to 50 times the molar equivalent of the ammonium acid group; more preferably, the amount of the acid anhydride added is 3 to 30 times the molar equivalent of the ammonium acid group. The basic catalyst is, for example, but not limited to, pyridine, triethylamine, trimethylamine, tributylamine, or trioctylamine. Pyridine is preferred because it has a moderately basic nature that allows the reaction to proceed. The acid anhydride is, for example, but not limited to, acetic anhydride, trimellitic anhydride, or phenylmethyltetrahydroquinone. When acetic anhydride is used, purification after the reaction is easier, so it is preferred. The imidization rate of the catalyst can be controlled by adjusting the amount of catalyst, reaction temperature, and / or reaction time.

[0240] When recovering the imidized polymer formed from the above-mentioned imidization reaction solution, the reaction solution is added to a solvent and allowed to precipitate. Solvents used for precipitation include, but are 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 in the solvent, it can be dried at room temperature or under normal or reduced pressure. Alternatively, the polymer recovered from precipitation can be dissolved in a solvent and reprecipitated; this operation can be repeated 2 to 10 times to reduce impurities in the polymer. Solvents used can be, for example, alcohols or ketone hydrocarbons. Using three or more of the selected solvents can further improve the purification efficiency, making it ideal.

[0241] Solution Viscosity and Molecular Weight of Polymers

[0242] When preparing a solution containing 10 wt% to 15 wt% of a first polymer (A1) or a second polymer (A2), the viscosity of the solution containing the first polymer (A1) or the second polymer (A2) is not particularly limited. For ease of operation, the viscosity of the solution containing the first polymer (A1) or the second polymer (A2) can be, for example, from 10 mPa·s to 1000 mPa·s. The viscosity (mPa·s) of the polymer-containing solution is the value measured at 25°C using a rotational viscometer, after preparing a solution containing 10 wt% to 15 wt% of the polymer using a good solvent for the polymer (e.g., γ-butyrolactone or N-methyl-2-pyrrolidone).

[0243] In some embodiments of the present invention, preferably, 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) based on polystyrene, is between 1,000 and 500,000; more preferably, the weight-average molecular weight based on polystyrene is between 2,000 and 500,000. Furthermore, preferably, the molecular weight distribution (Mw / Mn) expressed as the ratio of Mw to the number-average molecular weight (Mn) of polystyrene measured by GPC is 15 or less; more preferably, Mw / Mn is 10 or less. When the molecular weight of the polymer is within the above-mentioned range, good alignment and stability of the liquid crystal display element can be ensured.

[0244] End-capping agent

[0245] In some embodiments of the present invention, when synthesizing the first polymer (A1) or the second polymer (A2) of the present invention, the tetracarboxylic acid dianhydride component and the diamine component as described above can be used, and an end-sealing polymer can be synthesized using a suitable end-sealing agent. The end-sealing polymer has the effect of improving the film hardness of the liquid crystal alignment film obtained by coating, and improving the adhesion properties of the sealant and the liquid crystal alignment film. The ends of the first polymer (A1) or the second polymer (A2) of the present invention can be, for example, amino, carboxyl, anhydride, or derivatives of the above groups. Amino, carboxyl, anhydride, or derivatives of the above groups can be obtained by a general condensation reaction, or by sealing the ends using the end-sealing agent described below. Similarly, the above derivatives can be obtained, for example, using the end-sealing agent described below.

[0246] The capping agent is, for example, but not limited to, acid anhydrides, dicarbonate ester compounds, chlorocarbonyl compounds, monoamine compounds, or monoisocyanate compounds. The acid anhydrides are, for example, but not limited to, acetic anhydride, maleic anhydride, nerate 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 dicarbonate ester compounds are, for example, but not limited to, di-tert-butyl dicarbonate or diallyl dicarbonate. The chlorocarbonyl compounds are, for example, but not limited to, acryloyl chloride, methacryloyl chloride, or nicotinic chloride. The monoamine compounds include, but are 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 compounds include, but are not limited to, ethyl isocyanate, phenyl isocyanate, or naphthyl isocyanate.

[0247] The capping agent can be used alone or in combination. In some embodiments of the invention, preferably, based on a total amount of 100 moles of the diamine component, the amount of the capping agent used is from 0.01 moles to 20 moles; more preferably, the amount of the capping agent used is from 0.01 moles to 10 moles.

[0248] Other Polymers

[0249] In some embodiments of the present invention, the polymer component (A) of the liquid crystal alignment agent used in the photoalignment method of the present invention may optionally also include other polymers. These other polymers are, for example, but not limited to, polyesters, polyamides, polyureas, polyorganosiloxanes, cellulose derivatives, polyacetals, polystyrene or derivatives thereof, poly(styrene-phenylmaleimide) derivatives, or poly(meth)acrylates, etc.

[0250] Solvent (B)

[0251] From the viewpoint of forming a uniform thin film, the liquid crystal alignment agent is taken in the form of a coating liquid to produce a liquid crystal alignment film. Preferably, the liquid crystal alignment agent used in the photoalignment method of the present invention is a coating liquid containing a polymer component (A), a solvent (B), and a compound (C). The concentration of the polymer component (A) in the liquid crystal alignment agent used in the photoalignment method can be appropriately varied depending on the desired coating thickness. From the viewpoint of forming a uniform and defect-free coating film, preferably, the concentration of the polymer component (A) in the liquid crystal alignment agent used in the photoalignment method is 1 wt% or more. From the viewpoint of solution storage stability, preferably, the concentration of the polymer component (A) in the liquid crystal alignment agent used in the photoalignment method is 10 wt% or less. Ideally, the concentration of the polymer component (A) is between 2 wt% and 8 wt%. The content of polymer component (A) in the liquid crystal alignment agent used in the photoalignment 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 polymer component (A) is 2wt% to 10wt%; more preferably, the content of polymer component (A) is 3wt% to 8wt%.

[0252] The solvent (B) in the liquid crystal alignment agent used in the photoalignment method is, for example, an organic solvent, and there are no particular limitations on the solvent (B), as long as it can uniformly dissolve the polymer component (A) and the compound (C). The solvent (B) includes, but is not limited to, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyllactic acid, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, γ-valerolactone, 1,3-dimethyl-2-imidazolidineone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide. Amines, 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, etc., are all considered 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, the total amount of solvent (B) used in the liquid crystal alignment agent for the photoalignment method is 100 wt%, and the amount of good solvent used is 20 wt% to 99 wt%; preferably, the amount of good solvent used is 20 wt% to 90 wt%; more preferably, the amount of good solvent used is 30 wt% to 80 wt%.

[0253] In some embodiments of the present invention, preferably, the solvent (B) in the liquid crystal alignment agent used in the photoalignment method comprises the aforementioned good solvent and a poor solvent that can improve the coatability and surface smoothness of the coating film during liquid crystal alignment agent coating. Preferably, based on the total amount of solvent (B) used in the liquid crystal alignment agent used in the photoalignment method being 100 wt%, the amount of the poor solvent used is 1 wt% to 80 wt%; more preferably, the amount of the poor solvent used is 10 wt% to 80 wt%; even more preferably, the amount of the poor solvent used is 20 wt% to 70 wt%. The type and amount of the poor solvent can be appropriately selected according to the coating apparatus, coating conditions, and / or coating environment of the liquid crystal alignment agent.

[0254] The undesirable solvents mentioned include, but are not limited to, diisopropyl ether, diisobutyl ether, diisobutylmethanol (2,6-dimethyl-4-heptanol), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-butoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, ethylene glycol monobutyl ether (butyl cellosolve), ethylene glycol monoisopentyl ether, ethylene glycol monohexyl ether, propylene glycol monobutyl ether, and 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.

[0255] In some embodiments of the present invention, preferably, the undesirable solvent is diisobutyl methanol, propylene glycol monobutyl ether, propylene glycol diacetate, diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, or diisobutyl ketone, etc.

[0256] 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-dimethyllacticamide and diisobutyl ketone; N-methyl-2-pyrrolidone and ethyl 3-ethoxypropionate; N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate. N-methyl-2-pyrrolidone with ethylene glycol monobutyl ether acetate; N-ethyl-2-pyrrolidone with dipropylene glycol dimethyl ether; N,N-dimethyl lactamide with ethylene glycol monobutyl ether; N,N-dimethyl lactamide with propylene glycol diacetate; N-ethyl-2-pyrrolidone with diethylene glycol diethyl ether; N,N-dimethyl lactamide with diethylene glycol diethyl ether; N-methyl-2-pyrrolidone, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone with diethylene glycol diethyl ether; N-ethyl-2-pyrrolidone, N-methyl-2-pyrrolidone with 4-hydroxy-4-methyl-2-pentanone; N-ethyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone with 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- Butyrolactone with propylene glycol monobutyl ether and diisopropyl ether; N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether and diisobutylmethanol; N-methyl-2-pyrrolidone, γ-butyrolactone and dipropylene glycol dimethyl ether; N-methyl-2-pyrrolidone, propylene glycol monobutyl ether and dipropylene glycol dimethyl ether; 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-dimethyllactic acid and diisobutyl ketone, etc.

[0257] The solvent (B) can be used alone or in combination with other solvents. In some embodiments of the invention, based on a total usage of 100 parts by weight of the polymer component (A), the amount of solvent (B) used is 800 to 4000 parts by weight; preferably, the amount of solvent (B) used is 900 to 3500 parts by weight; more preferably, the amount of solvent (B) used is 1000 to 3000 parts by weight.

[0258] Compound (C)

[0259] The compound (C) comprises the structure shown in formula (c-1).

[0260] (c-1)

[0261] In the above equation (c-1), R 1 This indicates an n-valent organic group containing an aliphatic or aromatic hydrocarbon group with 1 to 20 carbon atoms; n represents an integer from 2 to 6; R 2 The R indicates an alkyl group, an alkenyl group, or an alkynyl group having 5 to 20 carbon atoms. 2 It may have substituents selected from at least one of methoxy, ethoxy, halogen, hydroxy, phenyl and tolyl, and the substituents contain at least one hydroxyl group.

[0262] In some embodiments of the present invention, the R 1 For example, but not limited to, groups as shown in formulas (c01) to (c06); the R 2 For example, but not limited to groups represented by formulas (c07) to (c19). "Indicates the location of the bond."

[0263] (c01) (c02)

[0264] (c03)

[0265] (c04)

[0266] (c05)

[0267] (c06)

[0268] (c07) (c08)

[0269] (c09) (c10)

[0270] (c11) (c12)

[0271] (c13)

[0272] (c14) (c15)

[0273] (c16) (c17)

[0274] (c18) (c19)

[0275] In some embodiments of the present invention, the compound (C) is selected from at least one of compounds having the structure shown in formula (c-1-1) and compounds having the structure shown in formula (c-1-2).

[0276] (c-1-1)

[0277] (c-1-2)

[0278] In the above formula (c-1-1), R 3 R 4 R 5 Each of the above independently represents an alkyl group, an alkenyl group, or an alkynyl group having 1 to 20 carbon atoms, and the R group... 3 The R 4 The R 5 It may have substituents, said substituents being selected from at least one of methoxy, ethoxy, halogen, hydroxy, phenyl, and tolyl, and said R 3 The substituents of R contain at least one hydroxyl group. 3 The R 4 The R 5 The total number of carbon atoms is 4 or more; R 6 This indicates an m-valent organic group containing an aliphatic or aromatic hydrocarbon group with 1 to 20 carbon atoms, where m represents an integer from 2 to 6.

[0279] In the above equation (c-1-2), R 7 R 8 R 9Each of the above independently represents an alkyl group, an alkenyl group, or an alkynyl group having 1 to 20 carbon atoms, and the R group... 7 The R 8 The R 9 It may have substituents, said substituents being selected from at least one of methoxy, ethoxy, halogen, hydroxy, phenyl, and tolyl, and said R 7 The substituents of R contain at least one hydroxyl group. 7 The R 8 The R 9 The total number of carbon atoms is 3 or more; R 10 It represents a p-valent organic group containing an aliphatic or aromatic hydrocarbon group with 1 to 20 carbon atoms, where p represents an integer from 2 to 6.

[0280] In some embodiments of the present invention, preferably, when R in formula (c-1-1) 4 The substituents contain at least one hydroxyl group, and the liquid crystal display element comprising the liquid crystal photoalignment film formed by the liquid crystal alignment agent used in the photoalignment method has good heat resistance.

[0281] In some embodiments of the present invention, preferably, when R in formula (c-1-2) 8 The substituents contain at least one hydroxyl group, and the liquid crystal display element comprising the liquid crystal photoalignment film formed by the liquid crystal alignment agent used in the photoalignment method has good heat resistance.

[0282] In some embodiments of the present invention, the R 6 and the R 10 For example, but not limited to, groups as shown in formulas (c01) to (c06) above.

[0283] In some embodiments of the present invention, the compound having the structure shown in formula (c-1-1) includes, for example but not limited to, R in the structure shown in formula (c-1). 1 The groups represented by formulas (c01) to (c06) and R 2 The combination of groups represented by formulas (c07) to (c13).

[0284] In some embodiments of the present invention, the compound having the structure shown in formula (c-1-2) includes, for example but not limited to, the R in the structure shown in formula (c-1). 1 The groups represented by formulas (c01) to (c06) and R 2 The combination of groups represented by formulas (c14) to (c19).

[0285] In some embodiments of the present invention, the compound (C) is, for example, but not limited to, compounds of formulas (C-1) to (C-6).

[0286] (C-1)

[0287] (C-2)

[0288] (C-3)

[0289] (C-4)

[0290] (C-5)

[0291] (C-6)

[0292] In some embodiments of the present invention, based on a total usage of 100 parts by weight of the polymer component (A), the usage of the compound (C) ranges from 0.5 parts by weight to 20 parts by weight; preferably, the usage of the compound (C) ranges from 1 part by weight to 18 parts by weight; more preferably, the usage of the compound (C) ranges from 2 parts by weight to 15 parts by weight.

[0293] When the liquid crystal alignment agent used in the photoalignment method does not contain the compound (C), the liquid crystal display element containing the liquid crystal photoalignment film formed by the liquid crystal alignment agent used in the photoalignment method is prone to poor heat resistance.

[0294] Additives (D)

[0295] In some embodiments of the present invention, the liquid crystal alignment agent used in the photoalignment method further comprises an additive (D). The additive (D) includes, but is not limited to, adhesion promoters for improving the adhesion between the liquid crystal alignment film and the substrate or between the liquid crystal alignment film and the sealant, crosslinking compounds for improving the strength of the liquid crystal alignment film, compounds for promoting imidization, and dielectric or conductive materials for adjusting the dielectric constant or resistance of the liquid crystal alignment film.

[0296] <Sealing Agent>

[0297] The sealing 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-ureopropyltrimethoxysilane, 3-ureopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethyleneethyltriamine, N-trimethoxysilylpropyltriethyleneethyltriamine, vinyltrimethoxysilane, etc. Silane coupling agents such as methyl silane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-epoxypropoxypropylmethyldimethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-epoxypropoxypropyltriethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-acryloyloxypropyltrimethoxysilane, tris(3-trimethoxysilylpropyl)isocyanurate, or 3-isocyanatepropyltriethoxysilane. When using the aforementioned binding agent, based on the viewpoint of exhibiting good resistance to AC image retention, it is preferable that the amount of the binding agent used is from 0.1 to 30 parts by weight relative to the total amount of polymer component (A) in the liquid crystal alignment agent used in the photoalignment method is 100 parts by weight; more preferably, the amount of the binding agent used is from 0.1 to 20 parts by weight.

[0298] <Cross-linked compounds>

[0299] Based on the viewpoint of exhibiting good resistance to AC image retention and effectively improving film strength, the crosslinking compound may be a compound having ethylene oxide, propylene oxide, at least one group selected from the group consisting of the group shown in formula (D1) and the group shown in formula (D2), or a compound selected from the compound shown in formula (D3).

[0300] (D1)

[0301] (D2)

[0302] (D3)

[0303] In the aforementioned formula (D1), G 1 and G 2Each of these independently represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or -CH2-OH. In formula (D2), G 3 Indicates 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 This represents a hydrogen atom, 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. In formula (D3), G 5 This indicates an organic group with (g1+g2) valence containing an aromatic ring; G 6 g1 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; g1 represents an integer from 1 to 6; g2 represents an integer from 0 to 4.

[0304] In the aforementioned formula (D3), G 5 The (g1+g2) valence organic groups representing aromatic rings can be exemplified by (g1+g2) valence aromatic hydrocarbon groups having 6 to 30 carbon atoms, (g1+g2) valence organic groups formed by direct or interleaved linkages of aromatic hydrocarbon groups having 6 to 30 carbon atoms, or (g1+g2) valence groups having aromatic heterocycles. The aromatic hydrocarbons can be, for example, benzene or naphthalene. The aromatic heterocycles can be exemplified by the specific nitrogen-containing structures described above. The linkages can be exemplified by alkylene groups having 1 to 10 carbon atoms or groups from which one hydrogen atom is removed, or divalent or trivalent cyclohexane, etc. Any hydrogen atom of the alkylene group can also be replaced by a fluorine atom or an organic group such as trifluoromethyl. In formula (D3), G 6 The alkyl groups represented by carbons from 1 to 5 can be methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, or n-pentyl.

[0305] [Compounds containing ethylene oxide]

[0306] Specific examples of the ethylene oxide-containing compounds include N,N,N',N'-tetracyclooxypropyl-m-xylenediamine, 1,3-bis(N,N-dicyclooxypropylaminomethyl)cyclohexane, N,N,N',N'-tetracyclooxypropyl-4,4'-diaminodiphenylmethane, N,N,N',N'-tetracyclooxypropyl-p-phenylenediamine, and compounds containing nitrogen atoms as shown in formulas (D4) to (D6) below.

[0307] (D4) (D5)

[0308] (D6)

[0309] [Compounds containing propylene oxide]

[0310] Specific examples of the compounds having an alkylene oxide content can be listed as compounds represented by formulas (D7) to (D16).

[0311] (D7)

[0312] (D8)

[0313] (D9)

[0314] (D10)

[0315] (D11)

[0316] (D12)

[0317] (D13)

[0318] (D14) (D15) (D16)

[0319] In equation (D7), n represents 1 to 3. In equation (D13), n represents 1 to 3. In equation (D14), n represents 1 to 100. In equation (D15), R represents... “ " represents the bond position. In the above formula (D16), n represents 1 to 10.

[0320] [Compounds having groups as shown in formula (D1)]

[0321] Specific examples of compounds having groups as shown in formula (D1) are listed below as compounds shown in formulas (D1-1) to (D1-12).

[0322] (D1-1)

[0323] (D1-2)

[0324] (D1-3)

[0325] (D1-4)

[0326] (D1-5)

[0327] (D1-6)

[0328] (D1-7)

[0329] (D1-8)

[0330] (D1-9)

[0331] (D1-10)

[0332] (D1-11)

[0333] (D1-12)

[0334] [Compounds having groups as shown in formula (D2)]

[0335] Specific examples of compounds having groups as shown in formula (D2) can be listed as compounds shown in formulas (D2-1) to (D2-4).

[0336] (D2-1) (D2-2)

[0337] (D2-3) (D2-4)

[0338] In equation (D2-1), n ​​represents 2 to 16. In equation (D2-2), n represents 2 to 16.

[0339] [Compounds having groups as shown in formula (D3)]

[0340] Specific examples of compounds having groups as shown in formula (D3) are compounds shown in formulas (D3-1) to (D3-10).

[0341] (D3-1) (D3-2)

[0342] (D3-3) (D3-4)

[0343] (D3-5) (D3-6)

[0344] (D3-7) (D3-8)

[0345] (D3-9) (D3-10)

[0346] In some embodiments of the present invention, the total amount of polymer component (A) in the liquid crystal alignment agent used in the photoalignment method is 100 parts by weight. Preferably, the amount of the crosslinking compound used is 0.5 parts by weight to 20 parts by weight. More preferably, based on the viewpoint of the progress of the crosslinking reaction and good resistance to AC image retention, the amount of the crosslinking compound used is 1 part by weight to 15 parts by weight.

[0347] <Compounds used to promote imidization>

[0348] In some embodiments of the present invention, preferably, the compound used to promote imidization is a compound having a basic site [e.g., a primary amino group, an aliphatic heterocycle (such as a pyrrolidine skeleton), an aromatic heterocycle (such as an imidazole ring or an indole ring), or a guanidine group, etc.] (excluding the aforementioned crosslinking compounds and binding aids), or a compound that produces the basic site upon calcination. More preferably, the compound used to promote imidization is a compound that produces the basic site upon calcination, and specific examples may be, for example, amino acids in which some or all of the basic site is a protected amino acid. Specific examples of the aforementioned amino acids include glycine, alanine, cysteine, methionine, aspartate, glutamine, valine, leucine, phenylalanine, tyrosine, tryptophan, proline, hydroxyproline, arginine, histidine, lysine, or ornithine. For the purpose of promoting imidization, more preferably, specific examples of compounds for promoting imidization can be listed as N-α-(9-fluorenylmethoxycarbonyl)-N-τ-(tert-butoxycarbonyl)-L-histidine.

[0349] Fabrication Method of Liquid Crystal Photoalignment Film and Liquid Crystal Display Element

[0350] The liquid crystal photoalignment film of the present invention is obtained from the liquid crystal alignment agent used in the aforementioned photoalignment method. The liquid crystal photoalignment film of the present invention can be used as a horizontally aligned or vertically aligned (VA type) liquid crystal photoalignment film, and is suitable as a liquid crystal photoalignment film for horizontally aligned liquid crystal display elements such as IPS or FFS types. The liquid crystal display element of the present invention includes the liquid crystal photoalignment film. The liquid crystal display element of the present invention can be manufactured, for example, by the methods described in steps (1) to (4) or steps (1) to (2) and (4) below.

[0351] Step (1): Apply liquid crystal alignment agent to the substrate.

[0352] Using a suitable coating method such as roll coating, spin coating, printing, or inkjet printing, the liquid crystal alignment agent for the photoalignment method of the present invention is coated on one side of a substrate having a patterned transparent conductive film. The substrate is not particularly limited; it only needs to be a highly transparent substrate, and glass or silicon nitride substrates can be used in combination with plastic substrates such as acrylic or polycarbonate substrates. Furthermore, in reflective liquid crystal display elements, if only a single-sided substrate is used, an opaque material such as a silicon wafer can be used, and the electrodes used can be made of light-reflective materials such as aluminum. Moreover, when manufacturing IPS or FFS type liquid crystal display elements, the comb-type uses an electrode substrate composed of a patterned transparent conductive film or metal film and an opposing substrate without electrodes.

[0353] Methods for coating the liquid crystal alignment agent used in the photoalignment method onto a substrate and forming a film include screen printing, offset printing, flexographic printing, inkjet printing, and spray coating. Preferably, the film formation method utilizes inkjet coating.

[0354] Step (2): Calcination of the coated liquid crystal alignment agent

[0355] Step (2) is the calcination of the liquid crystal alignment agent coated on the substrate to form a film. After the liquid crystal alignment agent for photoalignment is coated onto the substrate, the solvent can be evaporated by heating means such as a hot plate, a thermally circulating oven, or an infrared oven, or thermal imidization of polyamic acid or polyamic acid ester can be performed. The drying and calcination steps performed after coating the liquid crystal alignment agent for photoalignment can be performed at any temperature and time, and multiple drying or calcination steps can be performed. The temperature of the drying step can be, for example, 40°C to 180°C. From the viewpoint of shortening the processing time, 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 calcination step is not particularly time-limited, and can be 5 to 40 minutes or 5 to 30 minutes. If the film obtained after the calcination step is too thin, the reliability of the liquid crystal display element will be reduced. Therefore, preferably, the thickness of the film is 5 nm to 300 nm, and more preferably, the thickness of the film is 10 nm to 200 nm.

[0356] Step (3): Perform alignment treatment on the membrane obtained in step (2).

[0357] Step (3) involves performing alignment treatment on the film obtained in step (2), depending on the circumstances. That is, in horizontally aligned liquid crystal display elements such as IPS or FFS types, alignment treatment is performed on the film to impart alignment capability. On the other hand, in vertically aligned liquid crystal display elements such as VA or PSA types, the formed film can be used directly as a liquid crystal photoalignment film, but alignment treatment can also be performed on the film to impart alignment capability. Alignment treatment of the liquid crystal alignment film includes, but is not limited to, rubbing treatment or photoalignment treatment; preferably, the alignment treatment is a photoalignment treatment. The photoalignment treatment involves, for example, irradiating the surface of the film with radiation that has been deflected in a certain direction, and, depending on the circumstances, heating it at a temperature of 150°C to 250°C to impart liquid crystal alignment properties (also called liquid crystal alignment capability). The radiation can be ultraviolet 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; more preferably, the radiation is ultraviolet light with a wavelength of 200 nm to 400 nm.

[0358] The radiation dose can be 1 mJ / cm². 2 Up to 10,000 mJ / cm 2 Preferably, the radiation dose is 100 mJ / cm². 2 Up to 5,000 mJ / cm 2 More preferably, the radiation dose is 100 mJ / cm². 2 Up to 1500mJ / cm 2 Preferably, the radiation dose is 100 mJ / cm². 2 Up to 1000mJ / cm 2 When using a general liquid crystal alignment agent, the light irradiation dose for the alignment treatment is 100 mJ / cm². 2 Up to 5000mJ / cm 2 However, the liquid crystal alignment agent of the present invention can still form a liquid crystal photoalignment film in which variations (non-uniformity) in the liquid crystal alignment within the film surface are effectively suppressed, even if the light irradiation amount during alignment treatment is reduced. During irradiation, in order to improve liquid crystal alignment, the substrate having the film can be heated at 50°C to 250°C simultaneously with irradiation. The liquid crystal photoalignment film produced in this manner allows liquid crystal molecules to be stably aligned in a certain direction. Furthermore, the liquid crystal photoalignment film irradiated with polarized light in the above method can be contacted with a solvent, or the irradiated liquid crystal photoalignment film can be heat-treated.

[0359] The solvent used in the contact treatment is not particularly limited, as long as it can dissolve the decomposition products generated from the film after radiation irradiation. The solvent used in the contact treatment includes, but is not limited to, 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. From the viewpoint of versatility and safety, preferably, the solvent used in the contact treatment is water, 2-propanol, 1-methoxy-2-propanol, or ethyl lactate; more preferably, the solvent used in the contact treatment is water, 1-methoxy-2-propanol, or ethyl lactate. The solvent used in the contact treatment can be used alone or in combination.

[0360] In some embodiments of the present invention, preferably, the temperature for heating the irradiated film is between 50°C and 300°C, more preferably, the temperature for heating is between 120°C and 250°C. Preferably, the heating time is between 1 minute and 30 minutes.

[0361] Step (4): Fabrication of liquid crystal cells

[0362] Prepare two substrates with liquid crystal photoalignment films formed on their surfaces, and place liquid crystal between the two substrates facing each other. For example, two methods can be described below. In the first method, the two substrates are first arranged facing each other with their liquid crystal photoalignment films facing each other, separated by a gap (intercellular space). Then, the peripheries of the two substrates are bonded together with a sealant. Next, the liquid crystal composition is injected and filled into the intercellular space separated by the substrate surfaces and the sealant. After contacting the film surface, the injection hole is sealed.

[0363] The second method is called the ODF (One Drop Fill) method. A UV-curable sealant, such as an ODF sealant, is applied to predetermined positions on one of two substrates on which a liquid crystal photoalignment film is formed. Then, a liquid crystal composition is dropped onto multiple predetermined positions on the surface of the liquid crystal photoalignment film. Next, the other substrate is bonded with the liquid crystal photoalignment films facing each other, pressing the liquid crystal composition against the entire surface of the liquid crystal photoalignment film, bringing it into contact with the surface of the other liquid crystal photoalignment film. Then, the entire surface of the substrate is irradiated with UV light to harden the sealant. Preferably, when performing any of the above methods, 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. Furthermore, when performing a friction treatment on the film, the two substrates are arranged facing each other at a predetermined angle to the friction direction of each film, for example, orthogonal or antiparallel. The sealant can be, for example, an epoxy resin containing a hardener and alumina spheres as spacers. The liquid crystal composition is, for example, a nematic liquid crystal or a lamellar liquid crystal, preferably a nematic liquid crystal.

[0364] A polarizing plate can be attached to the outer surface of the liquid crystal cell as needed to obtain a liquid crystal display element. The polarizing plate attached to the outer surface of the liquid crystal cell is, for example, a polarizing film that extends and aligns with polyvinyl alcohol while simultaneously absorbing iodine, and is called an "H film". The polarizing plate can be a polarizing plate sandwiched with a cellulose acetate protective film, or a polarizing plate composed of the H film itself.

[0365] The present invention will be further described with reference to the following embodiments, but it should be understood that the embodiments are for illustrative purposes only and should not be construed as limiting the implementation of the present invention.

[0366] [Synthesis Example A1-1] First polymer (A1) – polyimide precursor

[0367] A nitrogen inlet, stirrer, condenser, and thermometer were installed on a 500 mL four-necked conical flask, and nitrogen gas was introduced. Then, 0.035 mol (70 mol%) of diamine compound b1-1-1, 0.010 mol (20 mol%) of diamine compound b1-2-1, 0.005 mol (10 mol%) of diamine compound b1-3-1, and 80 g of N-methyl-2-pyrrolidone were added and stirred at room temperature (25 °C) until dissolved. Next, 0.050 mol (100 mol%) of tetracarboxylic acid dianhydride compound a1-1-1 and 20 g of N-methyl-2-pyrrolidone were added, and the mixture was reacted at room temperature (25 °C) for 2 hours to obtain a reaction solution. The reaction solution was poured into 1500 mL of water to precipitate the polymer. The solution was then filtered to obtain a filter cake. The filter cake was then washed with methanol, filtered, washed with methanol, and filtered again, for a total of three times, to obtain the crude product. Next, the crude product is placed in a vacuum oven and dried at 60°C to obtain the first polymer (A1).

[0368] [Synthetic Examples A1-2 to A1-6] First Polymer (A1) – Polyimide Precursor

[0369] The first polymer (A1) of Synthetic Examples A1-2 to A1-6 was prepared using a method similar to that of Synthetic Example A1-1, except that the types and amounts of the tetracarboxylic acid dianhydride component (a1) and the diamine component (b1) were changed in Synthetic Examples A1-2 to A1-6, as shown in Table 1.

[0370] Table 1

[0371]

[0372] [Synthesis Example A2-1] Second polymer (A2) – polyimide precursor

[0373] A nitrogen inlet, stirrer, condenser, and thermometer were installed on a 500 mL four-necked conical flask, and nitrogen gas was introduced. Then, 0.040 mol (80 mol%) of diamine compound b2-1, 0.010 mol (20 mol%) of diamine compound b2-2, and 80 g of N-methyl-2-pyrrolidone were added, and the mixture was stirred at room temperature (25 °C) until dissolved. Next, 0.05 mol (100 mol%) of tetracarboxylic acid dianhydride compound a2-1 and 20 g of N-methyl-2-pyrrolidone were added, and the mixture was reacted at room temperature (25 °C) for 2 hours to obtain a reaction solution. The reaction solution was poured into 1500 mL of water to precipitate the polymer. The solution was then filtered to obtain a filter cake. The filter cake was then washed with methanol, filtered, washed with methanol, and filtered again, for a total of three times, to obtain the crude product. Next, the crude product was placed in a vacuum oven and dried at 60°C to obtain the second polymer (A2).

[0374] [Synthetic Examples A2-2 to A2-3] Second Polymer (A2) – Polyimide Precursor

[0375] The second polymer (A2) of Synthetic Examples A2-2 to A2-3 was prepared using a method similar to that of Synthetic Example A2-1, except that the types and amounts of the tetracarboxylic acid dianhydride component (a2) and the diamine component (b2) were changed in Synthetic Examples A2-2 to A2-3, as shown in Table 2.

[0376] Table 2

[0377]

[0378] [Synthesis Example C-1] Compound (C)

[0379] In a 0.5 L reactor, 0.85 mol of reactant A [3-amino-3-methylbutan-1-ol] and 40 mL of ethylene glycol were added. The mixture was stirred and heated to 80 °C. Then, 0.4 mol of reactant B [dimethyl adipate] was added, and the temperature was raised to 120 °C and maintained for 3 hours. The temperature was then lowered to 80 °C, isopropanol was added, and the mixture was allowed to stand until a solid precipitated. Finally, the solid was collected by filtration and dried to obtain compound C-1, as shown in Table 3.

[0380] [Synthetic Examples C-2 to C-6] Compound (C)

[0381] Synthetic Examples C-2 to C-6 were prepared in a manner similar to that of Synthetic Example C-1, with the difference being that the types of reactant A and / or reactant B were changed, as shown in Table 3.

[0382] Table 3

[0383]

[0384]

[0385]

[0386] [Example 1] Liquid crystal alignment agent, liquid crystal photoalignment film and liquid crystal display element used in photoalignment method

[0387] 100 parts by weight of the first polymer (A1) of Synthesis Example A1-1, 1200 parts by weight of solvent (B) [of type N-methyl-2-pyrrolidone] and 0.5 parts by weight of compound (C) of Synthesis Example C-1 were stirred and mixed at room temperature (25°C) to obtain a liquid crystal alignment agent for photoalignment.

[0388] The liquid crystal alignment agent for photoalignment is spin-coated onto the pixel electrode of a glass substrate containing the pixel electrode. The pixel electrode is an IPS driving electrode having a pair of indium tin oxide (ITO) electrodes (10 μm wide, 10 μm spaced, and 50 nm high). The ITO electrodes are serrated, with the serrated portions arranged in a separated and interlocking manner. The glass substrate coated with the liquid crystal alignment agent is then dried on a heating plate at 80°C for 3 minutes, followed by baking in a hot air circulating oven at 250°C for 30 minutes to form a 100 nm thick film of the liquid crystal alignment agent on the glass substrate. The film is then irradiated with 254 nm ultraviolet light through a polarizing plate, and then baked in a hot air circulating oven at 250°C for 30 minutes to form a liquid crystal photoalignment film, thus obtaining a first laminate containing the liquid crystal photoalignment film.

[0389] The liquid crystal alignment agent for photoalignment is spin-coated onto a glass substrate without pixel electrodes and having columnar spacers with a height of 4 μm. The glass substrate coated with the liquid crystal alignment agent is then dried on a heating plate at 80°C for 3 minutes, followed by baking in a hot air circulating oven at 250°C for 30 minutes to form a 100 nm thick film of the liquid crystal alignment agent on the glass substrate. The film is then irradiated with 254 nm ultraviolet light through a polarizing plate, and then baked in a hot air circulating oven at 250°C for 30 minutes to form a liquid crystal photoalignment film, thus obtaining a second laminate containing the liquid crystal photoalignment film.

[0390] A sealant is printed on one of the first and second laminates. Then, the liquid crystal photoalignment films of the first and second laminates are bonded together with their alignment directions at 0°. The sealant is then hardened to obtain a laminate containing an injection port and liquid crystal cell holes communicating with the injection port. Next, liquid crystal MLC-2041 (manufactured by Merck) is injected into the liquid crystal cell holes using a depressurized injection method, and the injection port is sealed. Then, two polarizing plates are respectively disposed perpendicularly on the top and bottom surfaces of the laminate, as defined by the glass substrate, to obtain a liquid crystal display element.

[0391] [Examples 2 to 12 and Comparative Examples 1 to 3] Liquid crystal alignment agent, liquid crystal photoalignment film and liquid crystal display element for photoalignment method

[0392] Examples 2 to 12 and Comparative Examples 1 to 3 were obtained by a method similar to that of Example 1, which yielded liquid crystal alignment agent, liquid crystal photoalignment film and liquid crystal display element for photoalignment method. The difference was that Examples 2 to 12 and Comparative Examples 1 to 3 changed the types and / or amounts of the first polymer (A1), second polymer (A2), solvent (B) and compound (C) in the liquid crystal alignment agent for photoalignment method, as shown in Tables 4 to 5.

[0393] [Evaluation Items]

[0394] The following description uses Example 1 as an example. Examples 2 to 12 and Comparative Examples 1 to 3 are carried out in the same manner.

[0395] Heat resistance: At 23°C, a voltage of 5V was applied to the liquid crystal display element of Example 1 with an application time of 60 microseconds and an application period of 167 milliseconds. The voltage retention rate of the liquid crystal display element of Example 1 was measured 167 milliseconds after the voltage was removed to obtain a first voltage retention rate (VHR1). After measuring the first voltage retention rate, the liquid crystal display element of Example 1 was placed in an oven at 100°C and left to stand for 300 hours. Then, the liquid crystal display element of Example 1 was cooled to room temperature (25°C), and the voltage retention rate was measured in the same manner as described above to obtain a second voltage retention rate (VHR2). Then, the rate of change of voltage retention rate (ΔVHR, in %) before and after standing in the 100°C oven was calculated using the following formula.

[0396] ΔVHR=[(VHR1-VHR2) / VHR1]×100%

[0397] The evaluation method for heat resistance is as follows:

[0398] ◎: ΔVHR < 4%;

[0399] ○: 4%≤ΔVHR<6%;

[0400] △: 6%≤ΔVHR<8%;

[0401] ╳:ΔVHR≥8%.

[0402] Table 4

[0403]

[0404] Table 5

[0405]

[0406] Referring to Tables 4 and 5, the liquid crystal alignment agent used in the photoalignment method of Examples 1 to 12 was obtained by using compound (C) from Synthetic Examples C-1 to C-6. Therefore, after the liquid crystal display elements containing the liquid crystal photoalignment film formed by the liquid crystal alignment agent used in the photoalignment method of Examples 1 to 12 were placed in an oven at 100°C for 300 hours, the change rate of voltage retention rate of the liquid crystal display elements of Examples 1 to 12 was less than 6%, indicating that the liquid crystal display elements of Examples 1 to 12 have good heat resistance.

[0407] Referring to Table 5, the liquid crystal alignment agent used in the photoalignment method of Comparative Examples 1 to 3 did not use the compound (C) of Synthetic Examples C-1 to C-6. Therefore, after the liquid crystal display elements containing the liquid crystal photoalignment film formed by the liquid crystal alignment agent used in the photoalignment method of Comparative Examples 1 to 3 were placed in an oven at 100°C for 300 hours, the change rate of voltage retention rate of the liquid crystal display elements of Comparative Examples 1 to 3 was all above 8%, indicating that the heat resistance of the liquid crystal display elements of Comparative Examples 1 to 3 was poor.

[0408] On the other hand, referring to Tables 3 to 5, the liquid crystal alignment agents used in the photoalignment method of Examples 3 to 6 and 9 to 12 were obtained by using compounds (C) of Synthetic Examples C-3 to C-6. Compounds (C) of Synthetic Examples C-3 to C-6 contain two or more hydroxyl groups. Therefore, after the liquid crystal display elements containing the liquid crystal photoalignment films formed by the liquid crystal alignment agents used in the photoalignment method of Examples 3 to 6 and 9 to 12 were placed in an oven at 100°C for 300 hours, the change rate of voltage retention rate of the liquid crystal display elements of Examples 3 to 6 and 9 to 12 was less than 4%, indicating that the liquid crystal display elements of Examples 3 to 6 and 9 to 12 had better heat resistance.

[0409] In summary, the liquid crystal alignment agent used in the photoalignment method of the present invention, by using the compound (C), can impart good heat resistance to the liquid crystal display element comprising the liquid crystal photoalignment film formed by the liquid crystal alignment agent used in the photoalignment method, thus effectively achieving the purpose of the present invention.

[0410] However, the above description is merely an embodiment of the present invention and should not be construed as limiting the scope of the present invention. Any simple equivalent changes and modifications made in accordance with the claims and description of the present invention shall still fall within the scope of the claims of the present invention.

Claims

1. A liquid crystal alignment agent for photoalignment, characterized in that: The liquid crystal alignment agent used in the photoalignment method comprises: Polymer component (A) includes a first polymer (A1), 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; Solvent (B); and Compound (C); The polyimide precursor of the first polymer (A1) comprises a structure as shown in formula (I). (I) In equation (I), X 1 "This indicates at least one of the groups consisting of structures as shown in equations (I-1) to (I-7)". "Indicates the location of the bond, (I-1)、 (I-2)、 (I-3)、 (I-4)、 (I-5)、 (I-6)、 (I-7)， In the above formula (I-1), X 11 X 12 X 13 and X 14 Each of these can independently represent hydrogen, halogen, alkyl with 1 to 6 carbon atoms, alkenyl with 2 to 6 carbon atoms, alkynyl with 2 to 6 carbon atoms, monovalent organic group with 1 to 6 carbon atoms containing fluorine, or phenyl. In the above formula (I-7), X 15 With X 16 Each can be used independently to represent hydrogen or methyl. X 2 Indicates an alkyl group having 1 to 4 carbon atoms. X 3 Indicates an alkyl group having 1 to 4 carbon atoms. Y 1 Indicates a divalent organic group. The compound (C) comprises the structure shown in formula (c-1). (c-1) In the above equation (c-1), R 1 This indicates an n-valent organic group containing an aliphatic or aromatic hydrocarbon group with 1 to 20 carbon atoms. n represents an integer from 2 to 6. R 2 The R indicates an alkyl group, an alkenyl group, or an alkynyl group having 5 to 20 carbon atoms. 2 It may have substituents selected from at least one of methoxy, ethoxy, halogen, hydroxy, phenyl and tolyl, and the substituents contain at least one hydroxyl group.

2. The liquid crystal alignment agent for photoalignment according to claim 1, characterized in that: The compound (C) is selected from at least one of compounds having the structure shown in formula (c-1-1) and compounds having the structure shown in formula (c-1-2). (c-1-1) In the above formula (c-1-1), R 3 R 4 R 5 Each of the above independently represents an alkyl group, an alkenyl group, or an alkynyl group having 1 to 20 carbon atoms, and the R group... 3 The R 4 The R 5 It may have substituents, said substituents being selected from at least one of methoxy, ethoxy, halogen, hydroxy, phenyl, and tolyl, and said R 3 The substituents of R contain at least one hydroxyl group. 3 The R 4 The R 5 The total number of carbon atoms is 4 or more. R 6 This indicates an m-valent organic group containing an aliphatic or aromatic hydrocarbon group with 1 to 20 carbon atoms, where m represents an integer from 2 to 6. (c-1-2) In the above formula (c-1-2), R 7 R 8 R 9 Each of the above independently represents an alkyl group, an alkenyl group, or an alkynyl group having 1 to 20 carbon atoms, and the R group... 7 The R 8 The R 9 It may have substituents, said substituents being selected from at least one of methoxy, ethoxy, halogen, hydroxy, phenyl, and tolyl, and said R 7 The substituents of R contain at least one hydroxyl group. 7 The R 8 The R 9 The total number of carbon atoms is 3 or more. R 10 It represents a p-valent organic group containing an aliphatic or aromatic hydrocarbon group with 1 to 20 carbon atoms, where p represents an integer from 2 to 6.

3. The liquid crystal alignment agent for the photoalignment method according to claim 2, characterized in that: The R in formula (c-1-1) 4 The substituents contain at least one hydroxyl group.

4. The liquid crystal alignment agent for the photoalignment method according to claim 2, characterized in that: The R in formula (c-1-2) 8 The substituents contain at least one hydroxyl group.

5. The liquid crystal alignment agent for the photoalignment method according to claim 1, characterized in that: Based on the total amount of the polymer component (A) used being 100 parts by weight, the amount of the compound (C) used ranges from 0.5 parts by weight to 20 parts by weight.

6. The liquid crystal alignment agent for photoalignment according to claim 1, characterized in that: The X 1 It is selected from the structures shown in equations (I-1-1) to (I-1-6). (I-1-1)、 (I-1-2)、 (I-1-3)、 (I-1-4)、 (I-1-5)、 (I-1-6)。 7. The liquid crystal alignment agent for photoalignment according to claim 6, characterized in that: The X 1 The structure is as shown in equation (I-1-1). (I-1-1)。 8. The liquid crystal alignment agent for photoalignment according to claim 1, characterized in that: The polymer component (A) further includes a second polymer (A2), 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, wherein 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 diamine component (b2) comprises a diamine compound (b2-1) having a nitrogen-containing structure, and the nitrogen atom structure in the diamine compound (b2-1) is selected from at least one of the group consisting of nitrogen-containing heterocycles, secondary amino groups, and tertiary amino groups.

9. A liquid crystal photoalignment film, characterized in that: The liquid crystal photoalignment film is formed from a liquid crystal alignment agent used in the photoalignment method as described in any one of claims 1 to 8.

10. A liquid crystal display element, characterized in that: The liquid crystal display element includes the liquid crystal photoalignment film as described in claim 9.

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