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

Abstract

The invention provides a liquid crystal alignment agent for an optical alignment method, a liquid crystal alignment film and a liquid crystal display element, which can improve key resistance. The liquid crystal alignment agent comprises a polymer (A), a solvent (B) and hydroxyalkylamide (C). The polymer (A) includes a polymer (A1) and a polymer (A2). A precursor (A10) of the polymer (A1) contains a structure represented by formula (I). The precursor (A20) as the polymer (A2) is formed by reacting a composition containing a tetracarboxylic dianhydride (a2) and a diamine (b2). The diamine (b2) comprises diamine (b2-1) with a nitrogen atom-containing structure and / or diamine (b2-2) with a structure as shown in a formula (B22). The hydroxyalkylamide (C) has a structure as shown in a formula (C-1) and comprises at least two hydroxyalkyls. Formula (I) (B22) (C-1)

Description

TECHNICAL FIELD

[0001] The present application relates to a liquid crystal alignment agent for a photo-alignment method, and particularly to a liquid crystal alignment agent for a photo-alignment method having excellent key resistance, a liquid crystal alignment film, and a liquid crystal display element. BACKGROUND

[0002] Existing liquid crystal display elements are widely used as display components of personal computers, smart phones, mobile phones, or television receivers, etc. A liquid crystal display element can include, for example, a liquid crystal layer interposed between a device substrate and a color filter substrate, a pixel electrode and a common electrode for applying an electric field to the liquid crystal layer, an alignment film for controlling the alignment of liquid crystal molecules of the liquid crystal layer, and a thin film transistor (TFT) for switching an electronic signal supplied to the pixel electrode, etc. As a driving mode of liquid crystal molecules, a vertical electric field mode such as a TN (Twisted Nematic) mode and a VA (Vertical Alignment) mode, and a horizontal electric field mode such as an IPS (In-Plane Switching) mode and an FFS (Fringe Field Switching) mode are known.

[0003] Currently, the most popular liquid crystal alignment film in industry is obtained by rubbing a film surface composed of a polyimide obtained by imidization of a polyamic acid and / or a polyamide acid formed on an electrode substrate in one direction with a cloth of wool, nylon, or polyester, etc. Rubbing is a simple and high productivity industrial method. However, with the high performance, high resolution, and large size of liquid crystal display elements, scratches are formed on the surface of the alignment film due to dust, mechanical force, and static electricity generated by rubbing, and further various problems such as unevenness in the alignment processing surface are caused. As an alternative to rubbing, a photo-alignment method for imparting liquid crystal alignment ability by irradiating polarized radiation is known. For the photo-alignment method, Japanese Patent Laid-Open No. 9-297313 has disclosed a method using a photo-isomerization reaction, a method using a photo-crosslinking reaction, or a method using a photo-decomposition reaction, etc.

[0004] However, liquid crystal display elements containing existing liquid crystal alignment films produced by the photo-alignment method have a problem of poor key resistance, and cannot meet application requirements. SUMMARY

[0005] In view of the above, the present application aims to provide a liquid crystal alignment agent for a photo-alignment method, a liquid crystal alignment film, and a liquid crystal display element capable of improving key resistance.

[0006] The present application provides a liquid crystal alignment agent for a photo-alignment method, comprising: a polymer component (A), a solvent (B), and a hydroxyalkylamide (C). The polymer component (A) comprises a first polymer (A1) and a second polymer (A2). The first polymer (A1) is at least one polymer selected from the group consisting of a polyimide precursor (A10) and an imidized polymer of the polyimide precursor (A10). The polyimide precursor (A10) comprises a structure represented by the following formula (I). The second polymer (A2) is at least one polymer selected from the group consisting of a polyimide precursor (A20) and an imidized polymer of the polyimide precursor (A20). The polyimide precursor (A20) is formed by reacting a reaction composition comprising a tetracarboxylic dianhydride component (a2) and a diamine component (b2). The diamine component (b2) comprises at least one of a diamine compound (b2-1) having a nitrogen atom-containing structure and a diamine compound (b2-2) having a structure represented by the following formula (B22). The hydroxyalkylamide (C) has a structure represented by the following formula (C-1) and comprises at least two hydroxyalkyl groups.

[0007] Formula (I)

[0008] In formula (I), X1 is at least one selected from the group consisting of structures represented by the following formulas (I-1) to (I-7), represents a bonding position; X2 represents a hydrogen atom or an alkyl group having a carbon number of 1 to 4; and Y is a divalent organic group.

[0009] Formula (I-1) Formula (I-2) Formula (I-3)

[0010] Formula (I-4) Formula (I-5)

[0011] Formula (I-6) Formula (I-7)

[0012] In formula (I-1), X 11 ~X 14 independently represent a hydrogen atom, a halogen atom, an alkyl group having a carbon number of 1 to 6, an alkenyl group having a carbon number of 2 to 6, an alkynyl group having a carbon number of 2 to 6, a fluorine-containing monovalent organic group having a carbon number of 1 to 6, or a phenyl group.

[0013] In formula (I-7), X 15 , X 16 independently represent a hydrogen atom or a methyl group.

[0014] Formula (B22)

[0015] In formula (B22), A is a divalent organic group consisting of a benzene ring or an aromatic condensed ring, which is unsubstituted or in which one or more hydrogen atoms are substituted with a monovalent organic group other than an amine group; and R is a divalent saturated hydrocarbon group having 1 to 10 carbon atoms.

[0016] Formula (C-1)

[0017] In formula (C-1), R 11 is a divalent alkyl group having 1 to 6 carbon atoms, a divalent cycloalkyl group having 3 to 6 carbon atoms, or a divalent aromatic group; R 12 , R 13 each independently represents a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, or a hydroxyalkyl group having 1 to 6 carbon atoms; w is 2 or 3; the w functional groups are the same or different from each other; when w is 2, X is NH, O, or S; and when w is 3, X is N or P.

[0018] In one embodiment of the present application, the above-described X1is at least one selected from the group consisting of structures represented by the following formulae (I-1-1) to (I-1-6).

[0019] Formula (I-1-1) Formula (I-1-2) Formula (I-1-3)

[0020] Formula (I-1-4) Formula (I-1-5) Formula (I-1-6)

[0021] In one embodiment of the present application, the above-described X1is a structure represented by formula (I-1-1).

[0022] In one embodiment of the present application, the above-described diamine compound (b2-2) has a structure represented by the following formula (B22-0).

[0023] Formula (B22-0)

[0024] In formula (B22-0), R1is a divalent saturated hydrocarbon group having 1 to 10 carbon atoms, and the benzene ring is unsubstituted or in which one or more hydrogen atoms are substituted with a monovalent organic group other than an amine group.

[0025] In one embodiment of the present application, the above-described hydroxyalkylamide (C) is at least one selected from the group consisting of compounds represented by the following formulae (C-1-1) to (C-1-20).

[0026] Formula (C-1-1)

[0027] Equation (C-1-2)

[0028] Equation (C-1-3)

[0029] Equation (C-1-4)

[0030] Equation (C-1-5)

[0031] Equation (C-1-6)

[0032] Equation (C-1-7)

[0033] Equation (C-1-8)

[0034] Equation (C-1-9)

[0035] Formula (C-1-10)

[0036] Equation (C-1-11)

[0037] Equation (C-1-12)

[0038] Equation (C-1-13)

[0039] Equation (C-1-14)

[0040] Formula (C-1-15)

[0041] Equation (C-1-16)

[0042] Equation (C-1-17)

[0043] Formula (C-1-18)

[0044] Equation (C-1-19)

[0045] Formula (C-1-20)

[0046] In one embodiment of the present invention, the hydroxyalkylamide (C) described above comprises at least four hydroxyalkyl groups.

[0047] In one embodiment of the present invention, the total weight of the solid components of the liquid crystal alignment agent based on the photoalignment method is 100% by weight, and the amount of hydroxyalkylamide (C) used is 4% to 35% by weight.

[0048] The present invention further provides a liquid crystal alignment film, which is formed using a liquid crystal alignment agent by means of photoalignment as described above.

[0049] The present invention also provides a liquid crystal display element comprising the liquid crystal alignment film as described above.

[0050] Based on the above, since the liquid crystal alignment agent used in the photoalignment method of the present invention includes a specific hydroxyalkylamide (C), the problem of poor key resistance can be improved.

[0051] To make the above features and advantages of the present invention more apparent and understandable, specific embodiments are described in detail below. Detailed Implementation

[0052] <Liquid crystal alignment agent for photoalignment method>

[0053] This invention provides a liquid crystal alignment agent for photoalignment, comprising: a polymer component (A), a solvent (B), and a hydroxyalkylamide (C), and optionally, an additive (D). The various components of the liquid crystal alignment agent for photoalignment used in this invention will be described in detail below.

[0054] In the following text, "solid composition of liquid crystal alignment agent for photoalignment" refers to the components other than solvent (B); "total weight of solid composition of liquid crystal alignment agent for photoalignment" refers to the total weight of the components other than solvent (B).

[0055] [Polymer Component (A)]

[0056] The polymer component (A) includes a first polymer (A1) and a second polymer (A2).

[0057] First polymer (A1)

[0058] The first polymer (A1) is at least one polymer selected from the group consisting of polyimide precursor (A10) and imidized polymers of polyimide precursor (A10). The polyimide precursor (A10) is formed by reacting a reaction composition comprising a tetracarboxylic dianhydride component (a1) and a diamine component (b1).

[0059] For example, the first polymer (A1) is a polyimide precursor (A10) having an imide precursor structure of polyamic acid and polyamic acid ester, or the first polymer (A1) is an imidized polymer (i.e., a polyimide) formed from the polyimide precursor (A10), or the first polymer (A1) comprises the polyimide precursor (A10) and the imidized polymer. The first polymer (A1) may be used in one or more forms.

[0060] The polyimide precursor (A10) comprises the structure shown in formula (I) below:

[0061] Formula (I)

[0062] In equation (I), X1 is selected from at least one of the groups consisting of the structures shown in equations (I-1) to (I-7) below. X1 indicates the bond position; X2 indicates a hydrogen atom or an alkyl group with 1 to 4 carbon atoms; Y is a divalent organic group.

[0063] Formula (I-1) Formula (I-2) Formula (I-3)

[0064] Formula (I-4) Formula (I-5)

[0065] Formula (I-6) Formula (I-7)

[0066] In equation (I-1), X 11 ~X 14 Each of the following can be independently represented: hydrogen atom, halogen atom, alkyl group with 1 to 6 carbon atoms, alkenyl group with 2 to 6 carbon atoms, alkynyl group with 2 to 6 carbon atoms, fluorine-containing monovalent organic group or phenyl group with 1 to 6 carbon atoms.

[0067] In equation (I-7), X 15 X 16 Each can be used to represent a hydrogen atom or a methyl group independently.

[0068] Tetracarboxylic dianhydride component (a1)

[0069] In addition to tetracarboxylic dianhydride compounds, tetracarboxylic dianhydride derivatives such as tetracarboxylic dihalides, tetracarboxylic dialkyl esters, or tetracarboxylic dialkyl ester dihalides can also be used as tetracarboxylic dianhydride derivatives. Tetracarboxylic dianhydride component (a1) can be used alone or in combination with multiple tetracarboxylic dianhydride compounds or their derivatives.

[0070] Alicyclic tetracarboxylic dianhydride (a1-1)

[0071] In some embodiments of the present invention, the tetracarboxylic dianhydride component (a1) comprises an alicyclic tetracarboxylic dianhydride (a1-1) or a derivative thereof having a structure as shown in the following formula (A11).

[0072] Equation (A11)

[0073] In equation (A11), X1 is selected from at least one of the groups consisting of the structures shown in equations (I-1) to (I-7) below. Indicates the location of the bond.

[0074] Formula (I-1) Formula (I-2) Formula (I-3)

[0075] Formula (I-4) Formula (I-5)

[0076] Formula (I-6) Formula (I-7)

[0077] In equation (I-1), X 11 ~X 14 Each of the following can be independently represented: hydrogen atom, halogen atom, alkyl group with 1 to 6 carbon atoms, alkenyl group with 2 to 6 carbon atoms, alkynyl group with 2 to 6 carbon atoms, fluorine-containing monovalent organic group or phenyl group with 1 to 6 carbon atoms.

[0078] In equation (I-7), X 15 X 16 Each can be used to represent a hydrogen atom or a methyl group independently.

[0079] In formula (A11), X1 is preferably selected from at least one of the groups consisting of the structures shown in formulas (I-1-1) to (I-1-6) below, and more preferably the structure shown in formula (I-1-1). When X1 is the structure shown in formula (I-1-1), the liquid crystal display element comprising the liquid crystal alignment film formed by the liquid crystal alignment agent for photoalignment has better resistance to key presses.

[0080] Formula (I-1-1) Formula (I-1-2) Formula (I-1-3)

[0081] Formula (I-1-4) Formula (I-1-5) Formula (I-1-6)

[0082] Based on a total amount of 100 moles of tetracarboxylic dianhydride (a1), the amount of alicyclic tetracarboxylic dianhydride (a1-1) used is 30 to 100 moles, preferably 40 to 100 moles, and more preferably 50 to 100 moles.

[0083] Other tetracarboxylic dianhydrides (a1-2)

[0084] In some embodiments of the present invention, the tetracarboxylic dianhydride component (A10) further comprises other tetracarboxylic dianhydrides (a1-2). The other tetracarboxylic dianhydrides (a1-2) have the structure shown in the following formula (A12).

[0085] Equation (A12)

[0086] In formula (A12), X 21 To select at least one of the groups consisting of structures shown in equations (A12-1) to (A12-32) below, Indicates the location of the bond.

[0087] Equation (A12-1) Equation (A12-2)

[0088] Equation (A12-3) Equation (A12-4)

[0089] Equation (A12-5)

[0090] Equation (A12-6)

[0091] Equation (A12-7) Equation (A12-8)

[0092] Equation (A12-9) Equation (A12-10)

[0093] Equation (A12-11)

[0094] Equation (A12-12)

[0095] Equation (A12-13)

[0096] Equation (A12-14) Equation (A12-15)

[0097] Equation (A12-16) Equation (A12-17)

[0098] Equation (A12-18) Equation (A12-19)

[0099] Equation (A12-20) Equation (A12-21)

[0100] Equation (A12-22)

[0101] Equation (A12-23) Equation (A12-24)

[0102] Equation (A12-25)

[0103] Equation (A12-26)

[0104] Equation (A12-27)

[0105] Equation (A12-28)

[0106] Equation (A12-29)

[0107] Equation (A12-30)

[0108] Equation (A12-31) Equation (A12-32)

[0109] In formula (A12-1), a1 is 1 to 12.

[0110] In formula (A12-5), X 22 a represents a single bond, -O-, -CO-, -COO-, phenyl, sulfonyl or amide group, and a2 is 0 or 1.

[0111] In formula (A12-6), X 23 X 24 Each can independently represent a single bond, -O-, -CO-, -COO-, phenyl, sulfonyl, or amide group, with multiple X groups. 24 To indicate whether they are the same or different, a3 is 0 or 1.

[0112] In formula (A12-11), a4 ranges from 2 to 6.

[0113] In formula (A12-13), a5 is 1 or 2.

[0114] In formula (A12-14), X 25 Each of the following can independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a fluorine-containing monovalent organogroup having 1 to 6 carbon atoms, or a phenyl group, and multiple X's. 25 For the same or different. Based on the viewpoint of liquid crystal alignment, X 25 Preferably, it is a hydrogen atom, a halogen atom, a methyl group, or an ethyl group, more preferably a hydrogen atom or a methyl group.

[0115] As specific examples of equation (A12-5) or equation (A12-6), structures as shown in equations (A12-5-1) to (A12-5-9) and equations (A12-6-1) to (A12-6-7) can be listed below.

[0116] Equation (A12-5-1) Equation (A12-5-2)

[0117] Equation (A12-5-3) Equation (A12-5-4)

[0118] Formula (A12-5-5)

[0119] Equation (A12-5-6)

[0120] Formula (A12-5-7) Formula (A12-5-8)

[0121] Equation (A12-5-9)

[0122] Equation (A12-6-1)

[0123] Equation (A12-6-2)

[0124] Equation (A12-6-3)

[0125] Equation (A12-6-4)

[0126] Equation (A12-6-5)

[0127] Equation (A12-6-6)

[0128] Equation (A12-6-7)

[0129] Based on a total amount of 100 moles of tetracarboxylic dianhydride component (a1), the amount of other tetracarboxylic dianhydrides (a1-2) used is 0 to 70 moles, preferably 0 to 60 moles, and more preferably 0 to 50 moles.

[0130] Diamine component (b1)

[0131] The diamine component (b1) includes a diamine compound (b1-1) and a diamine compound having a carbamate protecting group (b1-2). Furthermore, the diamine component (b1) may also include other diamine compounds (b1-3).

[0132] Diamine compound (b1-1)

[0133] The diamine compound (b1-1) has the structure shown in formula (A22-1) or formula (A22-2).

[0134] Equation (A22-1)

[0135] Equation (A22-2)

[0136] In formula (A22-1), Y 31 This represents a divalent organic group as shown in formula (A22-3), and multiple Y... 32 Each can be independently represented by a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

[0137] In equation (A22-2), multiple Y 33 Each of these can be independently represented by a divalent organic group as shown in formula (A22-3').

[0138] Equation (A22-3)

[0139] Equation (A22-3').

[0140] In formula (A22-3), Ar independently represents a divalent benzene ring, a biphenyl structure, or a 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 31' 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; This indicates the location of the bond.

[0141] In formula (A22-3'), 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 33' 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; This indicates the location of the bond.

[0142] In the divalent organic groups shown in formula (A22-3) and (A22-3'), the monovalent substituents of the benzene ring, biphenyl structure, or naphthyl ring are, for example, halogen atoms, 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.

[0143] From the viewpoint of improving liquid crystal alignment, formula (A22-3) is preferably at least one of the groups shown in formulas (A22-3-1) to (A22-3-16). This indicates the location of the bond.

[0144] Equation (A221-3-1)

[0145] Equation (A22-3-2)

[0146] Equation (A22-3-3)

[0147] Equation (A22-3-4)

[0148] Equation (A22-3-5)

[0149] Equation (A22-3-6)

[0150] Equation (A22-3-7)

[0151] Formula (A22-3-8)

[0152] Equation (A22-3-9)

[0153] Formula (A22-3-10)

[0154] Equation (A22-3-11)

[0155] Equation (A22-3-12)

[0156] Formula (A22-3-13)

[0157] Equation (A22-3-14)

[0158] Formula (A22-3-15) Equation (A22-3-16)

[0159] In equations (A22-3-1) and (A22-3-13), m is 0 or 1, and n is 1 to 6. In equations (A22-3-2), (A22-3-4), (A22-3-5), (A22-3-7), (A22-3-8), (A22-3-11), and (A22-3-12), n is 1 to 6. In equations (A22-3-3), (A22-3-6), and (A22-3-9), n is 2 to 6. In equations (A22-3-10) and (A22-3-14), m is 1 to 3, and n is 1 to 4.

[0160] From the viewpoint of improving the alignment of liquid crystals, formula (A22-3') is preferably at least one of the groups shown in formulas (A22-3-7) to (A22-3-16).

[0161] When the diamine compound (b1-1) contains a variety of diamine compounds as shown in formula (A22-1), Y in formula (A22-1) is preferred. 31 The diamine compound representing at least one of the groups shown in formulas (A22-3-1) to (A22-3-14) and Y in formula (A22-3-1) 31 A combination of diamine compounds representing at least one of the groups shown in formulas (A22-3-15) to (A22-3-16).

[0162] As specific examples of diamine compounds as shown in formula (A22-2), diamine compounds as shown in formulas (A22-2-1) to (A22-2-5) can be listed for example.

[0163]

[0164] Equation (A22-2-1)

[0165]

[0166] Equation (A22-2-2)

[0167]

[0168] Equation (A22-2-3)

[0169]

[0170] Equation (A22-2-4)

[0171]

[0172] Equation (A22-2-5)

[0173] In equations (A22-2-1) and (A22-2-2), m ranges from 1 to 6, and n ranges from 1 to 6. In equation (A22-2-3), m ranges from 2 to 6, and n ranges from 2 to 6.

[0174] Diamine compounds (b1-1) may be used alone or in combination of multiple types.

[0175] Based on a total amount of 100 moles of diamine component (b1), the amount of diamine compound (b1-1) used is 20 to 90 moles, preferably 25 to 80 moles, and more preferably 30 to 70 moles.

[0176] Diamine compounds with carbamate protecting groups (b1-2)

[0177] 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 carbamate-based protecting group. The first polymer (A1) having a carbamate-based protecting group can be obtained by using a monomer having a carbamate-based protecting group as at least a portion of the reactants, or by using a monomer having a carbamate-based protecting group as a capping agent as described below. In some specific examples, the monomer having a carbamate-based protecting group is, for example, a diamine compound (b1-2) having a carbamate-based protecting group. Examples of carbamate-based protecting groups include, for example, tert-butoxycarbonyl (Boc) or 9-fluorenylmethoxycarbonyl (Fmoc).

[0178] The diamine compound having a carbamate-based protecting group (b1-2) is preferably a diamine compound having at least one aromatic group (e.g., a benzene ring), more preferably a diamine compound having at least one aromatic group and having an organic group other than the carbamate-based protecting group having 6 to 30 carbon atoms. Specific examples of the diamine compound having a carbamate-based protecting group (b1-2) include, for example, diamine compounds as shown in formulas (A23-1) to (A23-11) below.

[0179] Equation (A23-1)

[0180] Equation (A23-2) Equation (A23-3)

[0181] Equation (A23-4)

[0182] Equation (A23-5)

[0183] Equation (A23-6)

[0184] Equation (A23-7)

[0185] Equation (A23-8)

[0186] Equation (A23-9)

[0187] Equation (A23-10)

[0188] Equation (A23-11)

[0189] In equations (A23-1), (A23-2), (A23-9), and (A23-11), n ​​ranges from 1 to 6. In equations (A23-4) and (A23-7), m ranges from 1 to 6, and n ranges from 1 to 6.

[0190] Diamine compounds (b1-2) with carbamate-based protecting groups can be used alone or in combination of multiple types.

[0191] Based on a total amount of 100 moles of diamine component (b1), the amount of diamine compound (b1-2) with carbamate protecting group used is 2 to 60 moles, preferably 10 to 50 moles, and more preferably 15 to 40 moles.

[0192] Other diamine compounds (b1-3)

[0193] Other diamine compounds (b1-3) include, for example, diamine compounds with 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 with carboxyl groups, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, etc. Phenylacetone, 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 acezoline structures, etc.

[0194] Specific examples of diamine compounds having photoalignment groups include 4,4'-diaminoazobenzene or diamine compounds as shown in formulas (A24-1) to (A24-3) below.

[0195] Equation (A24-1)

[0196] Equation (A24-2)

[0197] Equation (A24-3)

[0198] Specific examples of diamine compounds having a carboxyl group include 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, 3,5-diaminobenzoic acid, or diamine compounds as shown in formulas (A24-4) to (A24-7) below.

[0199] Equation (A24-4)

[0200] Equation (A24-5)

[0201] Equation (A24-6)

[0202] Equation (A24-7)

[0203] In formula (A24-4), Y 51The numbers represent single bonds, -CH2-, -C2H4-, -C(CH3)2-, -CF2-, -C(CF3)2-, -O-, -CO-, -NH-, -N(CH3)-, -CONH-, -NHCO-, -CH2O-, -OCH2-, -COO-, -OCO-, -CON(CH3)-, or -N(CH3)CO-; m1 and m2 independently represent integers from 0 to 4, and (m1+m2) represents integers from 1 to 4.

[0204] In equation (A24-5), m3 and m4 independently represent integers from 1 to 5.

[0205] In formula (A24-6), Y 52 m5 represents a straight-chain or branched alkyl group with 1 to 5 carbon atoms; m5 represents an integer from 1 to 5.

[0206] In formula (A24-7), Y 53 and Y 54 Each of the following can be represented independently: 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.

[0207] Specific examples of diamine compounds having urea bonds include, for example, diamine compounds represented by formulas (A24-8) to (A24-10) below.

[0208] Equation (A24-8)

[0209] Equation (A24-9)

[0210] Equation (A24-10)

[0211] In equation (A24-8), n1 is 0 to 6 and n2 is 1 to 6.

[0212] In equation (A24-9), n1 is 1 to 6, and n2 is 1 to 6.

[0213] In equation (A24-10), n ranges from 1 to 6.

[0214] Specific examples of diamine compounds having amide bonds include, for example, diamine compounds as shown in formulas (A24-11) to (A24-13) below.

[0215] Equation (A24-11)

[0216] Equation (A24-12)

[0217] Equation (A24-13)

[0218] In equation (A24-12), n ranges from 1 to 6.

[0219] In equation (A24-13), n1 is 1 to 6, and n2 is 1 to 6.

[0220] Specific examples of diamine compounds with photopolymerizable groups at the end include 2-(2,4-diaminophenoxy)ethyl methacrylate or 2,4-diamino-N,N-diallyl aniline.

[0221] Specific examples of diamine compounds having siloxane bonds include, for instance, 3-bis(3-aminopropyl)-tetramethyldisiloxane.

[0222] Specific examples of diamine compounds having an oxazoline structure include, for example, diamine compounds as shown in formulas (A24-14) and (A24-15) below.

[0223] Equation (A24-14)

[0224] Equation (A24-15)

[0225] Other diamine compounds (b1-3) may be used alone or in combination of multiple types.

[0226] Based on a total amount of 100 moles of diamine component (b1), the amount of other diamine compounds (b1-3) used is 0 to 65 moles, preferably 0 to 50 moles, and more preferably 0 to 35 moles.

[0227] Second polymer (A2)

[0228] The second polymer (A2) is at least one polymer selected from the group consisting of polyimide precursor (A20) and imidized polymers of polyimide precursor (A20). The polyimide precursor (A20) is formed by reacting a reaction composition comprising a tetracarboxylic dianhydride component (a2) and a diamine component (b2).

[0229] For example, the second polymer (A2) is a polyimide precursor (A20) having an imide precursor structure of polyamic acid and polyamic acid ester; the second polymer (A2) is an imidized polymer (i.e., a polyimide) formed from the polyimide precursor (A20); or the second polymer (A2) comprises the polyimide precursor (A20) and the imidized polymer. It is worth noting that the second polymer (A2) does not include the structure shown in formula (A1-1) present in the first polymer (A1). The second polymer (A2) may use only one type or a mixture of multiple types.

[0230] 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 20 / 80 to 90 / 10, and more preferably 20 / 80 to 80 / 20.

[0231] Tetracarboxylic dianhydride component (a2)

[0232] Tetracarboxylic dianhydride component (a2) may include, for example, acyclic aliphatic tetracarboxylic dianhydride compounds, alicyclic tetracarboxylic dianhydride compounds, aromatic tetracarboxylic dianhydride compounds, or derivatives of these compounds. Specific examples of acyclic aliphatic tetracarboxylic dianhydride compounds, alicyclic tetracarboxylic dianhydride compounds, and aromatic tetracarboxylic dianhydride compounds may include, for example, compounds listed in tetracarboxylic dianhydride component (a1). Tetracarboxylic dianhydride component (a2) preferably contains X from an alicyclic tetracarboxylic dianhydride (a1-1) or its derivative, or other tetracarboxylic dianhydrides (a1-2). 21 This refers to a tetracarboxylic dianhydride compound or a derivative thereof selected from at least one of the groups consisting of structures shown in formulas (A12-1) to (A12-6). The tetracarboxylic dianhydride component (a2) may be used alone or in combination with a plurality of such compounds.

[0233] The tetracarboxylic dianhydride component (a2) is preferably X, which includes other tetracarboxylic dianhydrides (a1-2). 21 The term refers to a tetracarboxylic dianhydride compound (a2-1) or a derivative thereof selected from at least one of the groups consisting of structures shown in formulas (A12-5-2) to (A12-5-4), more preferably including a tetracarboxylic dianhydride compound shown in formula (III) below.

[0234] Equation (III)

[0235] Based on a total amount of 100 moles of tetracarboxylic acid dianhydride component (a2), the amount of tetracarboxylic acid dianhydride compound (a2-1) used is 30 to 100 moles, preferably 40 to 100 moles, and more preferably 50 to 100 moles.

[0236] Diamine component (b2)

[0237] The diamine component (b2) includes at least one of a diamine compound (b2-1) having a nitrogen-containing structure and a diamine compound (b2-2) having a structure as shown in formula (B22). Furthermore, the diamine component (b2) may also include other diamine compounds (b2-3).

[0238] Diamine compounds containing nitrogen atoms (b2-1)

[0239] Examples of nitrogen-containing structures in diamine compounds (b2-1) that have nitrogen-containing structures include, for example, heterocycles, secondary amine groups, and tertiary amine groups.

[0240] Examples of nitrogen-containing heterocycles in diamine compounds (b2-1) with nitrogen-containing atomic structures include 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, preferably pyridine, pyrimidine, pyrazine, piperidine, piperazine, quinoline, carbazole, or acridine.

[0241] The secondary and tertiary amine groups in the diamine compound (b2-1) with nitrogen-containing atomic structure have the structure shown in the following formula (B21).

[0242] Formula (B21)

[0243] In formula (B21), Z represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group, or an aryl group; This indicates the location of the bond.

[0244] The alkyl group having 1 to 10 carbon atoms can be, for example, methyl, ethyl, or propyl. The cycloalkyl group can be, for example, cyclohexyl. The aryl group can be, for example, phenyl or tolyl. Z is preferably a hydrogen atom or a methyl group.

[0245] Specific examples of diamine compounds (b2-1) having a nitrogen-containing atom structure include 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, 1,4-bis-(4-aminophenyl)-piperazine, 3,6-diaminoacridine, N-ethyl-3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, diamine compounds represented by formulas (B21-1) to (B21-8), or diamine compounds represented by formulas (B21-9) to (B21-26).

[0246] Equation (B21-1)

[0247] Equation (B21-2)

[0248] Equation (B21-3)

[0249] Equation (B21-4)

[0250] Equation (B21-5)

[0251] Equation (B21-6)

[0252] Equation (B21-7)

[0253] Equation (B21-8)

[0254] Equation (B21-9)

[0255] Equation (B21-10)

[0256] Equation (B21-11)

[0257] Equation (B21-12)

[0258] Equation (B21-13)

[0259] Equation (B21-14)

[0260] Equation (B21-15)

[0261] Equation (B21-16)

[0262] Equation (B21-17)

[0263] Equation (B21-18)

[0264] Equation (B21-19)

[0265] Formula (B21-20)

[0266] Equation (B21-21)

[0267] Equation (B21-22)

[0268] Equation (B21-23)

[0269] Equation (B21-24)

[0270] Equation (B21-25)

[0271] Equation (B21-26)

[0272] In equations (B21-5) and (B21-6), n represents 1 to 4.

[0273] Diamine compounds (b2-1) with nitrogen-containing structures can be used in single or multiple forms in combination.

[0274] Based on a total amount of 100 moles of diamine component (b2), the amount of diamine compound (b2-1) having a nitrogen-containing atom structure used is 15 to 100 moles, preferably 20 to 90 moles, and more preferably 25 to 80 moles.

[0275] Diamine compound (b2-2)

[0276] The diamine compound (b2-2) has the structure shown in the following formula (B22).

[0277] Equation (B22)

[0278] In formula (B22), A is a divalent organic group composed of a benzene ring or an aromatic fused ring, wherein the benzene ring and the aromatic fused ring are unsubstituted or one or more of their hydrogen atoms are substituted by a monovalent organic group other than an amino group; R is a divalent saturated hydrocarbon group with 1 to 10 carbon atoms.

[0279] The diamine compound (b2-2) has one amino group directly bonded to the aromatic ring in A, while the other amino group is bonded to a saturated hydrocarbon group with 1 to 10 carbon atoms.

[0280] Specific examples of a divalent organic group consisting of a benzene ring or an aromatic fused ring as A can be listed, for example, as shown in formulas (IV-1) to (IV-10) below, and these structures are unsubstituted or one or more of their hydrogen atoms are substituted by a monovalent organic group other than an amino group.

[0281] Formula (IV-1) Formula (IV-2)

[0282] Formula (IV-3) Formula (IV-4)

[0283] Formula (IV-5) Formula (IV-6)

[0284] Formula (IV-7)

[0285] Formula (IV-8)

[0286] Formula (IV-9)

[0287] Formula (IV-10)

[0288] In formula (B22), A exists in the structure of polyamic acid and polyimide, and is a site that can improve the liquid crystal alignment and charge accumulation properties of the liquid crystal alignment film. While the reason is unclear, when A is a π-conjugated aromatic group, the charge accumulation properties of the liquid crystal alignment film are better, making it highly suitable. Furthermore, when the number of benzene rings or fused rings in A is small, or when the fused rings in A are condensed from 2 to 3 benzene rings, good storage stability of the liquid crystal alignment agent for photoalignment is maintained, making it very suitable.

[0289] A is preferably the structure shown in formula (IV-1) or formula (IV-2), and A is more preferably the structure shown in formula (IV-1).

[0290] When A has the structure shown in formula (IV-1), the diamine compound (b2-2) has the structure shown in formula (B22-0).

[0291] Formula (B22-0)

[0292] In formula (B22-0), R1 is a divalent saturated hydrocarbon group with 1 to 10 carbon atoms, and the benzene ring is unsubstituted or one or more of its hydrogen atoms are substituted by a monovalent organic group other than an amino group.

[0293] Generally, when the polyamic acid or polyimide backbone is rigid, the glass transition temperature is usually high, which can lead to a deterioration in the storage stability of liquid crystal alignment agents used in photoalignment methods. Based on this, it is preferable to impart flexibility to the polyamic acid or polyimide backbone. Considering the voltage retention characteristics and liquid crystal alignment properties of the liquid crystal alignment film, R is a divalent saturated hydrocarbon group with 1 to 10 carbon atoms. R is a saturated hydrocarbon group with a linear, branched, or cyclic structure, and is preferably a divalent organic group without an aromatic ring. Since R does not contain an aromatic group, it also has the effect of reducing the absorbance of the liquid crystal alignment film in the visible-ultraviolet region. From the viewpoint of charge accumulation characteristics, R is preferably a saturated hydrocarbon group with 1 to 6 carbon atoms. From the viewpoint of liquid crystal alignment properties, R is preferably a linear saturated hydrocarbon group.

[0294] R is preferably the structure shown in the following formula (V).

[0295] -(CH2) r1 -(Q) r2 -(CH2) r3 - Equation (V)

[0296] In formula (V), Q is a divalent cycloalkyl group with 3 to 7 carbon atoms, preferably a divalent cyclobutyl, divalent cyclopentyl, or divalent cyclohexyl, and more preferably a divalent cyclohexyl group with a stable ring structure. r1 and r3 are 0 to 7, preferably 0 to 3; r2 is 0 or 1; r1, r2, and r3 are not all 0 at the same time.

[0297] Specific examples of diamine compounds (b2-2) include compounds represented by formulas (B22-1) to (B22-9) below. These compounds are unsubstituted or have one or more hydrogen atoms substituted by a monovalent organic group other than an amino group.

[0298] Equation (B22-1)

[0299] Equation (B22-2)

[0300] Equation (B22-3)

[0301] Equation (B22-4)

[0302] Equation (B22-5) Equation (B22-6)

[0303] Equation (B22-7) Equation (B22-8)

[0304] Equation (B22-9)

[0305] In formulas (B22-1) to (B22-4), the meanings of Q, r1 and r3 are the same as those in formula (V), and the sum of Q, the number of carbons in the cyclic hydrocarbon group, r1 and r3 is preferably 10 or less.

[0306] In equations (B22-5) to (B22-9), r4 ranges from 1 to 10.

[0307] As a specific example of diamine compounds (b2-2), compounds as shown in formulas (B22-10) to (B22-45) can be further listed. These compounds are unsubstituted or have one or more hydrogen atoms substituted by a monovalent organic group other than an amino group.

[0308] Equation (B22-10)

[0309] Equation (B22-11)

[0310] Equation (B22-12)

[0311] Equation (B22-13)

[0312] Equation (B22-14)

[0313] Equation (B22-15)

[0314] Equation (B22-16)

[0315] Equation (B22-17)

[0316] Equation (B22-18)

[0317] Equation (B22-19)

[0318] Equation (B22-20)

[0319] Equation (B22-21)

[0320] Equation (B22-22)

[0321] Equation (B22-23)

[0322] Equation (B22-24)

[0323] Equation (B22-25)

[0324] Equation (B22-26)

[0325] Equation (B22-27) Equation (B22-28)

[0326] Equation (B22-29)

[0327] Formula (B22-30)

[0328] Equation (B22-31)

[0329] Equation (B22-32)

[0330] Equation (B22-33)

[0331] Equation (B22-34)

[0332] Equation (B22-35)

[0333] Equation (B22-36)

[0334] Equation (B22-37)

[0335] Equation (B22-38)

[0336] Equation (B22-39)

[0337] Equation (B22-40)

[0338] Equation (B22-41)

[0339] Equation (B22-42)

[0340] Equation (B22-43)

[0341] Equation (B22-44)

[0342] Equation (B22-45)

[0343] Diamine compounds (b2-2) can be used alone or in combination of multiple types.

[0344] Based on a total amount of 100 moles of diamine component (b2), the amount of diamine compound (b2-2) used is 20 to 80 moles, preferably 25 to 75 moles, and more preferably 30 to 70 moles.

[0345] Other diamine compounds (b2-3)

[0346] Other diamine compounds (b2-3) can be briefly mentioned, such as the diamine compounds (b1-1) listed in the diamine component (b1), the diamine compounds (b1-2) with carbamate protecting groups, and other diamine compounds (b1-3), which will not be elaborated here.

[0347] [Methods for manufacturing the first polymer (A1) and the second polymer (A2)]

[0348] The first polymer (A1) and the second polymer (A2) can be manufactured by reacting the diamine component and the tetracarboxylic dianhydride component 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 having an amide acid structure (i.e., polyamic acid) is obtained.

[0349] There are no particular restrictions on the solvent used in the reaction, as long as it can dissolve the polymer formed. Examples of solvents include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, or 1,3-dimethyl-2-imidazolidineone. When the polymer has high solvent solubility, examples of solvents include methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or solvents as shown in formulas (D-1) to (D-3) below.

[0350] Equation (D-1)

[0351] Equation (D-2)

[0352] Equation (D-3)

[0353] In equation (D-1), Z 1 Represents 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 Indicates an alkyl group having 1 to 4 carbon atoms.

[0354] The solvent used for the reaction can be a single solvent or a mixture of several solvents. Furthermore, even a poor solvent 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 be carried out at any concentration, preferably 1% to 50% by weight, more preferably 5% to 30% by weight. The reaction can also be carried out at a high concentration initially, followed by the addition of additional solvent. During the reaction, the ratio of the total moles of the diamine component to the total moles of the tetracarboxylic dianhydride component is preferably 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.

[0355] Polymers having an amide ester structure can be obtained, for example, by existing methods, such as:

[0356] (1) A method for reacting the polyamic acid obtained by the above method with an esterifying agent.

[0357] (2) A method for reacting a tetracarboxylic acid diester compound with a diamine compound, or

[0358] (3) A method for reacting a tetracarboxylic acid diester dihalide with a diamine compound.

[0359] The imidized polymer in the first polymer (A1) or the second polymer (A2) can be obtained, for example, by cyclizing a polymer having an amide ester structure. In the imidized polymer, the cyclization rate (also known as the imidization rate) of the functional groups of the amide acid group or its derivatives does not necessarily have to be 100%, and the imidization rate of the imidized polymer can be adjusted arbitrarily according to the application and / or purpose.

[0360] Methods for obtaining imidized polymers 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 solution, the reaction temperature is preferably 100°C to 400°C, more preferably 120°C to 250°C. During thermal imidization, it is preferable to simultaneously remove the water generated during the imidization reaction from the system.

[0361] Catalytic imidization is carried out, for example, by adding an alkaline catalyst and an acid anhydride to a solution, preferably with stirring at -20°C to 250°C, more preferably at 0°C to 180°C. The amount of alkaline catalyst added is preferably 0.5 to 30 times the molar equivalent of the amide acid groups, more preferably 2 to 20 times. The amount of acid anhydride added is preferably 1 to 50 times the molar equivalent of the amide acid groups, more preferably 3 to 30 times. Examples of alkaline catalysts include pyridine, triethylamine, trimethylamine, tributylamine, or trioctylamine. Pyridine is particularly desirable because it provides a moderately alkaline reaction. Examples of acid anhydrides include acetic anhydride, trimellitic anhydride, or phenylmethyltetrahydroquinone. Acetic anhydride is particularly desirable because it facilitates purification after the reaction. The imidization rate of catalytic imidization can be controlled by adjusting the amount of catalyst, the reaction temperature, and / or the reaction time.

[0362] 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, which is ideal.

[0363] [Solvent (B)]

[0364] From the viewpoint of forming a uniform thin film, the liquid crystal alignment agent for photoalignment is taken in the form of a coating solution to produce a liquid crystal alignment film. The concentration of the polymer component (A) in the liquid crystal alignment agent for photoalignment can be appropriately varied based on the desired coating thickness. From the viewpoint of forming a uniform and defect-free coating, the concentration of the polymer component (A) in the liquid crystal alignment agent for photoalignment is preferably 1% by weight or more. From the viewpoint of the storage stability of the solution, the concentration of the polymer component (A) in the liquid crystal alignment agent for photoalignment is preferably 10% by weight or less. Ideally, the concentration of the polymer component (A) is 2% to 8% by weight. The content of the polymer component (A) in the liquid crystal alignment agent for photoalignment can be appropriately varied by the coating method of the liquid crystal alignment agent for photoalignment and / or the film thickness of the liquid crystal alignment film, preferably 2% to 10% by weight, more preferably 3% to 8% by weight.

[0365] As the solvent (B) in the liquid crystal alignment agent used in photoalignment, an organic solvent can be used, for example. There are no particular limitations on the solvent (B), as long as it can uniformly dissolve the polymer component (A). Examples of solvents (B) include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyllactic acid, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, γ-valerolactone, 1,3-dimethyl-2-imidazolidineone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide. The solvents used include 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., and the above-mentioned solvents are also called good solvents. Among them, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide, or γ-butyrolactone are preferred.

[0366] Based on the total amount of solvent (B) in the liquid crystal alignment agent used in the photoalignment method being 100% by weight, the amount of good solvent used is 20% to 99% by weight, preferably 20% to 90% by weight, and more preferably 30% to 80% by weight.

[0367] Secondly, the solvent (B) in the liquid crystal alignment agent for photoalignment is preferably a low-solvent containing the aforementioned good solvent and a solvent that improves the coatability and surface smoothness of the coating film during the application of the liquid crystal alignment agent for photoalignment. Based on a total solvent (B) of 100% by weight in the liquid crystal alignment agent for photoalignment, the amount of low-solvent used is preferably 1% to 80% by weight, more preferably 10% to 80% by weight, and even more preferably 20% to 70% by weight. The type and amount of low-solvent can be appropriately selected based on the coating apparatus, coating conditions, and / or coating environment of the liquid crystal alignment agent for photoalignment.

[0368] Examples of lean solvents include 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, propyl carbonate, ethyl carbonate, ethylene glycol monobutyl ether (butyl ceroxysulfate), ethylene glycol monoisopentyl ether, ethylene glycol monohexyl ether, propylene glycol monobutyl ether, 1-(2-butoxyethoxy)- 2-Propanol, 2-(2-Butoxyethoxy)-1-propanol, propylene glycol monomethyl ether acetate, propylene glycol diacetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethylene glycol acetate, propylene glycol diacetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, n-butyl lactate, isoamyl lactate, diethylene glycol monoethyl ether, or diisobutyl ketone (2,6-dimethyl-4-heptanone), etc.

[0369] The preferred solvents are diisobutylmethanol, 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.

[0370] Preferred examples of solvent combinations that combine good and poor solvents include, for example, 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 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-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 and 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.

[0371] Solvent (B) may be used alone or in combination of multiple solvents.

[0372] Based on a total amount of 100 parts by weight of polymer component (A), the amount of solvent (B) used is 800 to 4000 parts by weight, preferably 900 to 3500 parts by weight, and more preferably 1000 to 3000 parts by weight.

[0373] [Hydroxyalkylamide (C)]

[0374] The hydroxyalkylamide (C) has the structure shown in the following formula (C-1) and includes at least two hydroxyalkyl groups.

[0375] Equation (C-1)

[0376] In equation (C-1), R 11 It is a divalent alkyl group having 1 to 6 carbon atoms, a divalent cycloalkyl group having 3 to 6 carbon atoms, or a divalent aromatic group; R 12 R 13 Each of the following can be independently represented: hydrogen atom, hydroxyl group, alkyl group with 1 to 6 carbon atoms, or hydroxyalkyl group with 1 to 6 carbon atoms; w is 2 or 3; the w functional groups are the same or different from each other; when w is 2, X is NH, O or S; when w is 3, X is N or P.

[0377] Specific examples of hydroxyalkylamides (C) include compounds as shown in formulas (C-1-1) to (C-1-20) below.

[0378] Equation (C-1-1)

[0379] Equation (C-1-2)

[0380] Equation (C-1-3)

[0381] Equation (C-1-4)

[0382] Equation (C-1-5)

[0383] Equation (C-1-6)

[0384] Equation (C-1-7)

[0385] Equation (C-1-8)

[0386] Equation (C-1-9)

[0387] Formula (C-1-10)

[0388] Equation (C-1-11)

[0389] Equation (C-1-12)

[0390] Equation (C-1-13)

[0391] Equation (C-1-14)

[0392] Formula (C-1-15)

[0393] Equation (C-1-16)

[0394] Equation (C-1-17)

[0395] Formula (C-1-18)

[0396] Equation (C-1-19)

[0397] Formula (C-1-20)

[0398] When the liquid crystal alignment agent used in the photoalignment method does not contain hydroxyalkylamide (C), the resulting liquid crystal alignment film is prone to having poor resistance to key interactions.

[0399] When the hydroxyalkylamide (C) included in the liquid crystal alignment agent in the photoalignment method includes at least four hydroxyalkyl groups, the resulting liquid crystal alignment film has better resistance to key presses.

[0400] The amount of hydroxyalkylamide (C) used is 4% to 35% by weight, preferably 5% to 33% by weight, and more preferably 6% to 30% by weight, based on the total weight of the solid components of the liquid crystal alignment agent used in the photoalignment method, which is based on 100% by weight.

[0401] [Additive (D)]

[0402] Additives (D) may include, for example, adhesives for improving the adhesion between the liquid crystal alignment film and the substrate or 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 dielectrics or conductive materials for adjusting the dielectric constant or resistance of the liquid crystal alignment film.

[0403] Sealing agent

[0404] Examples of sealing agents include: 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureopropyltrimethoxysilane, 3-ureopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethyleneethyltriamine, N-trimethoxysilylpropyltriethyleneethyltriamine, vinyltrimethoxysilane... 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-isocyanate propyltriethoxysilane, etc. When using an adhesive additive, based on the viewpoint of exhibiting good resistance to AC image retention, and based on the total amount of polymer component (A) in the liquid crystal alignment agent for photoalignment method being 100 parts by weight, the amount of adhesive additive used is preferably 0.1 parts by weight to 30 parts by weight, more preferably 0.1 parts by weight to 20 parts by weight.

[0405] Cross-linked compounds

[0406] Based on the viewpoint that it exhibits good resistance to AC image retention and effectively improves film strength, the crosslinking compound may be a compound having ethylene oxide, propylene oxide, at least one group selected from the group consisting of groups represented by formulas (E1) and (E2) below, or a compound selected from the compound represented by formula (E3) below.

[0407] Equation (E1)

[0408] Equation (E2)

[0409] Equation (E3)

[0410] In formula (E1), G1 and G2 each independently represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or -CH2-OH. In formula (E2), G3 represents an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkynyl group having 2 to 6 carbon atoms. G4 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 (E3), G5 represents a (g1+g2) valence organic group containing an aromatic ring. G6 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. g1 represents an integer from 1 to 6, and g2 represents an integer from 0 to 4.

[0411] In formula (E3), the (g1+g2) valence organic group represented by G5 can be an aromatic hydrocarbon group with 6 to 30 carbon atoms, an aromatic hydrocarbon group with 6 to 30 carbon atoms bonded directly or alternately by a linking group, or an aromatic heterocycle group with an aromatic ring. The aromatic hydrocarbon can be, for example, benzene or naphthalene. The aromatic heterocycle can be exemplified by the specific nitrogen-containing structures described above. The linking group can be an alkyl group with 1 to 10 carbon atoms or a group from which one hydrogen atom is removed, or a divalent or trivalent cyclohexane, etc. Any hydrogen atom in the alkyl group can also be replaced by a fluorine atom or an organic group such as trifluoromethyl. In formula (E3), the alkyl group represented by G6 with 1 to 5 carbon atoms can be methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, or n-pentyl.

[0412] Compounds containing ethylene oxide

[0413] Specific examples of compounds containing ethylene oxide include N,N,N',N'-tetracyclooxypropylmethylenediamine, 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 (E4) to (E6) below.

[0414] Formula (E4)

[0415] Equation (E5)

[0416] Equation (E6)

[0417] Compounds containing propylene oxide

[0418] Specific examples of compounds containing propylene oxide can be listed as compounds shown in formulas (E7) to (E16) below.

[0419] Equation (E7)

[0420] Equation (E8)

[0421] Equation (E9)

[0422] Formula (E10)

[0423] Equation (E11)

[0424] Equation (E12)

[0425] Equation (E13)

[0426] Equation (E14)

[0427] Equation (E15)

[0428] Equation (E16)

[0429] In formula (E15), R represents , This indicates the location of the bond.

[0430] Compounds having groups as shown in formula (D-1)

[0431] Specific examples of compounds having groups as shown in formula (E1) can be listed as compounds shown in formulas (E-1) to (E-13) below.

[0432] Equation (E-1)

[0433] Equation (E-2)

[0434] Equation (E-3)

[0435] Equation (E-4)

[0436] Equation (E-5)

[0437] Equation (E-6)

[0438] Equation (E-7)

[0439] Equation (E-8)

[0440] Equation (E-9)

[0441] Formula (E-10)

[0442] Equation (E-11)

[0443] Equation (E-12)

[0444] Equation (E-13)

[0445] Compounds having groups as shown in formula (E2)

[0446] Specific examples of compounds having groups as shown in formula (E2) can be listed as compounds shown in formulas (E2-1) to (E2-4) below.

[0447] Equation (E2-1)

[0448] Equation (E2-2)

[0449] Equation (E2-3)

[0450] Equation (E2-4)

[0451] Compounds having groups as shown in formula (E3)

[0452] Specific examples of compounds having groups as shown in formula (E3) are compounds as shown in formulas (E3-1) to (E3-10) below.

[0453] Equation (E3-1) Equation (E3-2)

[0454] Equation (E3-3) Equation (E3-4)

[0455] Equation (E3-5)

[0456] Equation (E3-6)

[0457] Equation (E3-7) Equation (E3-8)

[0458] Equation (E3-9)

[0459] Equation (E3-10)

[0460] The total amount of polymer component (A) in the liquid crystal alignment agent for photoalignment is 100 parts by weight, and the amount of crosslinking compound used is preferably 0.5 parts by weight to 20 parts by weight. From the viewpoint that the crosslinking reaction proceeds and exhibits good resistance to AC image retention, the amount of crosslinking compound used is more preferably 1 part by weight to 15 parts by weight.

[0461] Compounds that promote imidization

[0462] The compound used to promote imidization is preferably 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.) (except for the aforementioned crosslinking compounds and binding aids), or a compound that produces a basic site upon calcination. More preferably, the compound promoting imidization is a compound that produces a basic site upon calcination, and specific examples may be, for example, an amino acid in which part or all of the basic site is protected. Specific examples of the aforementioned amino acids include glycine, alanine, cysteine, methionine, asparagine, glutamic acid, valine, leucine, phenylalanine, tyrosine, tryptophan, proline, hydroxyproline, arginine, histidine, lysine, or ornithine. For the purpose of promoting imidization, a more preferred specific example is N-α-(9-fluorenylmethoxycarbonyl)-N-τ-(tert-butoxycarbonyl)-L-histidine.

[0463] <Manufacturing Method of Liquid Crystal Alignment Film and Liquid Crystal Display Element>

[0464] The liquid crystal alignment film of the present invention is obtained by using a liquid crystal alignment agent in the aforementioned photoalignment method. The liquid crystal alignment film of the present invention can be used as a horizontally aligned or vertically aligned (VA type) liquid crystal alignment film, and is suitable for liquid crystal alignment films of horizontally aligned liquid crystal display elements such as IPS or FFS types. The liquid crystal alignment film is included in the liquid crystal display element of the present invention. The liquid crystal display element of the present invention can be manufactured, for example, by the following steps (1) to (4) or steps (1) to (2) and (4).

[0465] Process (1): Applying a liquid crystal alignment agent to the substrate using the photoalignment method.

[0466] The photoaligning agent for liquid crystal alignment according to the present invention is coated on one side of a substrate having a patterned transparent conductive film using a suitable coating method such as roll coating, spin coating, printing, or inkjet coating. The substrate is not particularly limited; it only needs to be a highly transparent substrate. Glass substrates or silicon nitride substrates can be used in combination with plastic substrates such as acrylic substrates or polycarbonate substrates. Furthermore, in reflective liquid crystal display elements, if only a single-sided substrate is used, opaque materials such as silicon wafers can be used, and the electrodes can be made of light-reflective materials such as aluminum. Moreover, when manufacturing IPS or FFS type liquid crystal elements, the comb-type uses an electrode substrate composed of a patterned transparent conductive film or metal film and an opposing substrate without electrodes.

[0467] Methods for photoaligning liquid crystal alignment agents onto a substrate to form a film include screen printing, offset printing, flexographic printing, inkjet printing, and spraying. Among these, inkjet printing is the preferred method for film formation.

[0468] Process (2): Calcination of the coated liquid crystal alignment agent for photoalignment.

[0469] Step (2) is a step of calcining the photo-alignment liquid crystal alignment agent coated on the substrate to form a film. After the photo-alignment liquid crystal alignment agent is coated on the substrate, the solvent can be evaporated by heating means such as a hot plate, a thermally circulating oven, or an IR (infrared) oven, or thermal imidization of polyamic acid or polyamic acid ester can be performed. The drying and calcination steps performed after coating the photo-alignment liquid crystal alignment agent of the present invention can be performed at any temperature and time, and multiple drying or calcination steps can be performed. The drying temperature can be, for example, 40°C to 180°C. From the viewpoint of shortening the processing time, it can be performed at 40°C to 150°C. The drying time is not particularly limited, and can be, for example, 1 minute to 10 minutes or 1 minute to 5 minutes. When performing thermal imidization of polyamic acid or polyamic acid ester, after the aforementioned 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. There is no particular limitation on the calcination time, which can be 5 to 40 minutes or 5 to 30 minutes. If the calcined film is too thin, the reliability of the liquid crystal display element will be reduced. Therefore, the film thickness is preferably 5 nm to 300 nm, and more preferably 10 nm to 200 nm.

[0470] Step (3): Orientation treatment is performed on the membrane obtained in step (2).

[0471] Step (3) involves aligning the film obtained in step (2) as appropriate. In other words, in horizontally aligned liquid crystal display elements such as IPS or FFS types, the coating is aligned to impart alignment capability. On the other hand, in vertically aligned liquid crystal display elements such as VA or PSA types, the formed coating can be used directly as a liquid crystal alignment film, but it can also be aligned to impart alignment capability. Alignment processing of the liquid crystal alignment film can include rubbing or photoalignment, with photoalignment being preferred. Photoalignment can include irradiating the surface of the film with radiation that has been deflected in a certain direction, and, as appropriate, heating it at a temperature of 150°C to 250°C to impart liquid crystal alignment (also known as liquid crystal alignment capability). The radiation can be ultraviolet light or visible light with a wavelength of 100 nm to 800 nm, preferably ultraviolet light with a wavelength of 100 nm to 400 nm, and more preferably ultraviolet light with a wavelength of 200 nm to 400 nm.

[0472] The radiation dose mentioned above can be 1 mJ / cm 2 ~10,000 mJ / cm 2 Preferably 100 mJ / cm 2 ~5,000 mJ / cm 2 More preferably 100 mJ / cm 2 ~1500 mJ / cm 2 Therefore, the preferred value is 100 mJ / cm. 2 ~1000 mJ / cm 2 When using a general liquid crystal alignment agent, the light irradiation dose for the alignment treatment is 100 mJ / cm². 2 ~5000 mJ / cm 2 However, the liquid crystal alignment agent used in the photoalignment method of the present invention can still produce a liquid crystal alignment film in which variations (non-uniformity) in the liquid crystal alignment within the film surface are effectively suppressed, even if the amount of light irradiation during the alignment treatment is reduced. During irradiation, in order to improve the liquid crystal alignment, the substrate of the aforementioned film can be heated at 50°C to 250°C simultaneously with irradiation. The liquid crystal alignment film produced in this manner allows the liquid crystal molecules to be stably aligned in a specific direction. Furthermore, the liquid crystal alignment film irradiated with polarized light in the aforementioned method can be contacted with a solvent, or the irradiated liquid crystal alignment film can be heat-treated.

[0473] There are no particular restrictions on the solvent used for contact treatment, as long as it can dissolve the decomposition products generated from the film after radiation irradiation. Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl ceroxysulfate, ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, or cyclohexyl acetate. Among these, water, 2-propanol, 1-methoxy-2-propanol, or ethyl lactate are preferred from the viewpoint of versatility and safety, and are more preferably water, 1-methoxy-2-propanol, or ethyl lactate. Only one solvent or a mixture of several solvents may be used.

[0474] The preferred temperature for heat treatment of the aforementioned irradiated coating is 50°C to 300°C, and more preferably 120°C to 250°C. The preferred heat treatment time is 1 minute to 30 minutes.

[0475] Step (4): Fabrication of liquid crystal cells

[0476] Prepare two liquid crystal alignment film substrates as described above, and place liquid crystal between the two substrates facing each other. For example, the following two methods can be used. In the first method, firstly, arrange the two substrates facing each other with their respective liquid crystal alignment film surfaces facing each other, with a gap (intercellular space) between them. Then, bond the peripheral portions of the two substrates together with a sealant, and then inject the liquid crystal composition to fill the intercellular space separated by the substrate surface and the sealant. After it contacts the film surface, seal the injection hole.

[0477] The second method is called ODF (One Drop Fill). A UV-curable sealant is applied to predetermined positions on one of two substrates on which a liquid crystal alignment film has been formed. A liquid crystal composition is then dropped onto multiple predetermined positions on the liquid crystal alignment film surface. The other substrate is then bonded with the liquid crystal alignment films facing each other, and the liquid crystal composition is pressed onto the entire surface of the substrate, bringing it into contact with the film surface. Next, the entire surface of the substrate is irradiated with UV light to harden the sealant. When performing any of the aforementioned methods, it is preferable to further heat the liquid crystal composition to a temperature that becomes isotropic, and then slowly cool it to room temperature to remove the flow alignment during liquid crystal filling. Furthermore, when performing a friction treatment on the coating, the two substrates are arranged facing each other at a predetermined angle to the friction direction of each coating, for example, in an orthogonal or antiparallel manner. The sealant can be, for example, an epoxy resin containing a hardener and alumina spheres as spacers. Examples of liquid crystal compositions include nematic liquid crystals and smectic liquid crystals, with nematic liquid crystals being preferred.

[0478] 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 can be a polarizing film that extends and aligns with polyvinyl alcohol while simultaneously absorbing iodine, and is called an "H-film". It can be a polarizing plate sandwiched between a cellulose acetate protective film, or a polarizing plate composed of the H-film itself.

[0479] The present invention will be further described with reference to the following embodiments, but it should be understood that these embodiments are for illustrative purposes only and should not be construed as limiting the implementation of the present invention.

[0480] <Example>

[0481] [Example of synthesis of first polymer (A1) and second polymer (A2)]

[0482] The following describes an example of the synthesis of the first polymer (A1) and the second polymer (A2):

[0483] Synthesis example A1-1

[0484] A nitrogen inlet, stirrer, heater, condenser, and thermometer were installed on a 500 mL four-necked conical flask. After introducing nitrogen, 0.005 mol of a diamine compound having the group shown in formula (A22-3-7) (hereinafter referred to as b1-a), 0.0165 mol of a diamine compound having the group shown in formula (A22-3-11) (hereinafter referred to as b1-b), 0.0235 mol of p-phenylenediamine (hereinafter referred to as b1-c), 0.005 mol of a diamine compound shown in formula (A23-11) (hereinafter referred to as b1-d), and 80 g of N-methyl-2-pyrrolidone (NMP, hereinafter referred to as B-1) were added and stirred at room temperature until dissolved. Then, 0.05 mol of 1,3-dimethylcyclobutanetetracarboxylic acid dianhydride (hereinafter referred to as a1-a) and 20 g of B-1 were added, and the reaction was carried out at room temperature for 2 hours. After the reaction was complete, the reaction solution was poured into 1500 mL of water to precipitate the polymer. The obtained polymer was filtered, and the washing and filtration process was repeated three times with methanol. Then, the product was placed in a vacuum oven and dried at 60°C to obtain the first polymer (A1) of synthesis example A1-1.

[0485] Synthetic Examples A1-2 to A1-4 and Synthetic Examples A2-1 to A2-5

[0486] The first polymer (A1) of Synthetic Examples A1-2 to A1-4 and the second polymer (A2) of Synthetic Examples A2-1 to A2-5 were prepared using the same process as in Synthetic Example A-1, except that the types and amounts of the tetracarboxylic acid dianhydride component and the diamine component were changed. Their formulations are shown in Tables 1 and 2, and will not be described again here.

[0487] In addition, the compounds corresponding to the abbreviations in Tables 1 and 2 are shown below.

[0488]

[0489]

[0490] [Table 1]

[0491]

[0492] [Table 2]

[0493]

[0494] [Examples of liquid crystal alignment agents used in photoalignment methods]

[0495] The following describes examples of liquid crystal alignment agents used in photoalignment methods:

[0496] Example 1

[0497] 50 parts by weight of the first polymer (A1) of Synthetic Example A1-1 (hereinafter referred to as A1-1), 50 parts by weight of the second polymer (A2) of Synthetic Example A2-1 (hereinafter referred to as A2-1), and 30 parts by weight of the compound shown in formula (C-1-1) (hereinafter referred to as C-1) were added to 800 parts by weight of B-1 and stirred evenly with a shaking stirrer to obtain the liquid crystal alignment agent for photoalignment of Example 1. The prepared liquid crystal alignment agent for photoalignment of Example 1 was evaluated using the evaluation method described below, and the results are shown in Table 3.

[0498] Examples 2 to 9 and Comparative Examples 1 to 3

[0499] Examples 2 to 9 and Comparative Examples 1 to 3 were prepared using the same procedures as in Example 1, except that the types and amounts of the liquid crystal alignment agents used in the photoalignment method were changed. The formulations and evaluation results are shown in Table 3, and will not be repeated here.

[0500] Additionally, the compounds corresponding to the abbreviations in Table 3 are shown below.

[0501]

[0502] [Table 3]

[0503]

[0504] [Evaluation Method]

[0505] Key resistance

[0506] The photo-alignment liquid crystal alignment agent of the embodiments and comparative examples was spin-coated onto the pixel electrode of a glass substrate containing a pixel electrode. The pixel electrode was an IPS driving electrode having a pair of indium tin oxide (ITO) electrodes (electrode width 10 μm, electrode spacing 10 μm, electrode height 50 nm). The ITO electrodes were serrated, and the serrated portions were arranged in a separated and interlocking manner. Then, the glass substrate coated with the photo-alignment liquid crystal alignment agent was dried on a heating plate at 80°C for 3 minutes, and then baked in a hot air circulating oven at 250°C for 30 minutes to obtain a coating film with a thickness of 100 nm formed on the glass substrate. The coating film was irradiated with ultraviolet light with a wavelength of 254 nm through a polarizing plate, and then baked in a hot air circulating oven at 250°C for 30 minutes to obtain a first laminate containing a liquid crystal alignment film.

[0507] Next, the photo-alignment liquid crystal alignment agent of the embodiments and comparative examples was spin-coated onto a glass substrate without pixel electrodes and having columnar spacers with a height of 4 μm. Then, the glass substrate coated with the photo-alignment liquid crystal alignment agent was 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 obtain a coating film with a thickness of 100 nm formed on the glass substrate. The coating film was irradiated with ultraviolet light at a wavelength of 254 nm through a polarizing plate, and then baked in a hot air circulating oven at 250°C for 30 minutes to obtain a second laminate containing the liquid crystal alignment film.

[0508] A sealant is printed onto one of the first and second laminates. Then, the liquid crystal alignment films of the first and second laminates are bonded together with their alignment directions at 0°. The sealant is then cured to obtain a laminate containing an injection port and liquid crystal cell holes communicating with that 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. Finally, polarizing plates are attached perpendicularly to the top and bottom surfaces of the laminate to form a liquid crystal display element.

[0509] Finally, using a key testing machine (manufactured by Touch Panel Laboratories), a silicone rubber pen (model 3R) with a 3mm radius tip was used. The pen tip was aligned with the center of the liquid crystal display elements prepared in each embodiment and comparative example. After 10,000 key presses under a 500g load and a 10Hz frequency, the liquid crystal display elements prepared in each embodiment and comparative example were observed using a 100x microscope, and the number of bright spots was observed. A lower number of bright spots indicates better key resistance of the liquid crystal display element prepared using a liquid crystal alignment agent via photoalignment. The evaluation criteria are as follows:

[0510] ◎: Number of bright spots < 30

[0511] ○: Number of bright spots ≤ 30 < 50

[0512] △: Number of bright spots ≤ 50 < 100

[0513] ╳: The number of bright spots is ≥100.

[0514] <Evaluation Results>

[0515] As shown in Table 3, compared with the liquid crystal alignment agents for photoalignment (Examples 1-9) that include a specific hydroxyalkylamide (C), the liquid crystal alignment agents for photoalignment in Comparative Examples 1-3 do not include a specific hydroxyalkylamide (C), therefore the key resistance of the prepared liquid crystal alignment films is poor.

[0516] Furthermore, when the hydroxyalkylamide (C) includes at least four hydroxyalkyl groups (Examples 5-9), the resulting liquid crystal alignment film exhibits better resistance to key presses.

[0517] In summary, the liquid crystal alignment agent for photoalignment of the present invention includes a specific hydroxyalkylamide (C), thus enabling the acquisition of a liquid crystal alignment agent for photoalignment, a liquid crystal alignment film, and a liquid crystal display element that can improve resistance to key presses.

[0518] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A liquid crystal alignment agent for photoalignment, comprising: Polymer component (A); Solvent (B); and Hydroxyalkylamide (C) The polymer component (A) includes a first polymer (A1) and a second polymer (A2). The first polymer (A1) is at least one polymer selected from the group consisting of a polyimide precursor (A10) and imidized polymers of the polyimide precursor (A10), wherein the polyimide precursor (A10) comprises the structure shown in formula (I) below. The second polymer (A2) is at least one polymer selected from the group consisting of a polyimide precursor (A20) and imidized polymers of the polyimide precursor (A20), wherein the polyimide precursor (A20) is formed by reacting a reaction composition comprising a tetracarboxylic dianhydride component (a2) and a diamine component (b2). The diamine component (b2) includes at least one of a diamine compound (b2-1) having a nitrogen-containing atomic structure and a diamine compound (b2-2) having a structure as shown in the following formula (B22). The hydroxyalkylamide (C) has the structure shown in formula (C-1) below, and includes at least two hydroxyalkyl groups. Formula (I) In equation (I), X1 is selected from at least one of the groups consisting of the structures shown in equations (I-1) to (I-7) below. Indicates the bond position; X2 represents a hydrogen atom or an alkyl group with 1 to 4 carbon atoms; Y is a divalent organogroup; Formula (I-1) Formula (I-2) Formula (I-3) Formula (I-4) Formula (I-5) Formula (I-6) Formula (I-7) In equation (I-1), X 11 ~X 14 Each of the following can be independently represented: hydrogen atom, halogen atom, alkyl group with 1 to 6 carbon atoms, alkenyl group with 2 to 6 carbon atoms, alkynyl group with 2 to 6 carbon atoms, fluorine-containing monovalent organic group or phenyl group with 1 to 6 carbon atoms; In equation (I-7), X 15 X 16 Each can be used independently to represent a hydrogen atom or a methyl group; Formula (B22) In formula (B22), A is a divalent organic group composed of a benzene ring or an aromatic fused ring, wherein the benzene ring and the aromatic fused ring are unsubstituted or one or more of their hydrogen atoms are substituted by a monovalent organic group other than an amino group; R is a divalent saturated hydrocarbon group having 1 to 10 carbon atoms; Equation (C-1) In equation (C-1), R 11 It is a divalent alkyl group having 1 to 6 carbon atoms, a divalent cycloalkyl group having 3 to 6 carbon atoms, or a divalent aromatic group; R 12 R 13 Each of the following can be independently represented: hydrogen atom, hydroxyl group, alkyl group with 1 to 6 carbon atoms, or hydroxyalkyl group with 1 to 6 carbon atoms; w is 2 or 3; the w functional groups are the same or different from each other; when w is 2, X is NH, O or S; when w is 3, X is N or P.

2. The liquid crystal alignment agent for photoalignment according to claim 1, wherein, X1 is selected from at least one of the groups consisting of the structures shown in equations (I-1-1) to (I-1-6) below. Formula (I-1-1) Formula (I-1-2) Formula (I-1-3) Formula (I-1-4) Formula (I-1-5) Formula (I-1-6).

3. The liquid crystal alignment agent for photoalignment according to claim 2, wherein, X1 has the structure shown in equation (I-1-1).

4. The liquid crystal alignment agent for photoalignment according to claim 1, wherein, The diamine compound (b2-2) has the structure shown in the following formula (B22-0). Formula (B22-0) In formula (B22-0), R1 is a divalent saturated hydrocarbon group with 1 to 10 carbon atoms, and the benzene ring is unsubstituted or one or more of its hydrogen atoms are substituted by a monovalent organic group other than an amino group.

5. The liquid crystal alignment agent for photoalignment according to claim 1, wherein, The hydroxyalkylamide (C) is selected from at least one of the group consisting of compounds as shown in formulas (C-1-1) to (C-1-20). Equation (C-1-1) Equation (C-1-2) Equation (C-1-3) Equation (C-1-4) Equation (C-1-5) Equation (C-1-6) Equation (C-1-7) Formula (C-1-8) Equation (C-1-9) Formula (C-1-10) Equation (C-1-11) Equation (C-1-12) Equation (C-1-13) Equation (C-1-14) Formula (C-1-15) Equation (C-1-16) Equation (C-1-17) Formula (C-1-18) Equation (C-1-19) Formula (C-1-20).

6. The liquid crystal alignment agent for photoalignment according to claim 1, wherein, The hydroxyalkylamide (C) comprises at least four hydroxyalkyl groups.

7. The liquid crystal alignment agent for photoalignment according to claim 1, wherein, Based on the total weight of the solid components of the liquid crystal alignment agent used in the aforementioned photoalignment method being 100% by weight. The amount of the hydroxyalkylamide (C) used is 4% to 35% by weight.

8. A liquid crystal alignment film formed using a liquid crystal alignment agent according to any one of claims 1 to 7.

9. A liquid crystal display element comprising the liquid crystal alignment film as described in claim 8.

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