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

Abstract

The present invention provides a liquid crystal alignment agent, a liquid crystal alignment film and a liquid crystal display element. The liquid crystal alignment agent comprises a polymer (A) and a solvent (B). The polymer (A) is prepared by reacting a specific tetracarboxylic dianhydride component (a) and a diamine component (b). The liquid crystal alignment film is formed by the liquid crystal alignment agent, and the liquid crystal display element comprising the liquid crystal alignment film has a lower flickering degree after driving.

Description

Technical Field

[0001] The invention relates to a liquid crystal alignment agent, a liquid crystal alignment film and a liquid crystal display element, and in particular to a liquid crystal display element which utilizes the liquid crystal alignment agent to obtain a liquid crystal display element with better flickering degree immediately after being driven. Background Art

[0002] Liquid crystal display elements used in liquid crystal televisions, liquid crystal monitors, etc., are usually provided with a liquid crystal alignment film inside the element for controlling the arrangement state of the liquid crystal. Currently, the most common method in the industry is to rub the surface of a film formed on an electrode substrate and formed of polyamic acid and / or polyimide imidized therefrom in one direction with a cloth such as cotton, nylon, polyester, etc., to produce the liquid crystal alignment film by so-called rubbing treatment.

[0003] During the alignment process of the liquid crystal alignment film, the film surface is subjected to friction treatment, which is a relatively easy method to produce in industry. However, with the increasing requirements for high performance, high precision and large-scale liquid crystal display elements, during the friction treatment, various problems such as damage to the alignment film surface, flying dust, the influence of mechanical force and electrostatic force, and unevenness on the alignment treatment surface become more and more significant.

[0004] As a method to replace the friction treatment, there is currently known a photo-alignment method that uses polarized ultraviolet irradiation to impart alignment energy to the liquid crystal. The so-called photo-alignment method for liquid crystal alignment treatment includes substances that use photoisomerization reactions, substances that use photocrosslink reactions, substances that use photodecomposition reactions, etc. in the reaction mechanism. Furthermore, Japanese Patent Publication No. 9-297313 proposes that the photo-alignment method uses a polyimide film whose main chain has an alicyclic structure such as cyclobutane. When using polyimide as an alignment film for photo-alignment, because the heat resistance of this alignment film is higher than that of other types of alignment films, the applicability of this alignment film is optimistic.

[0005] The photo-alignment method is a method of alignment treatment without friction. In industry, it not only has the advantage of being manufactured using a simple process, but also in liquid crystal display elements driven by lateral electric field effect technology (In-Plane-Switching; IPS) and boundary electric field switching wide viewing angle technology (Fringe Field Switching; FFS) , the contrast and viewing angle characteristics of the liquid crystal display elements can be improved when the liquid crystal alignment film obtained by the photo-alignment method is used, compared with the liquid crystal alignment film obtained by the friction treatment method. Therefore, the photo-alignment method is a promising and highly anticipated liquid crystal alignment treatment method.

[0006] However, when the liquid crystal alignment film obtained by the photo-alignment method is applied to a liquid crystal display element, the obtained liquid crystal display element still has the problem of poor flickering degree immediately after driving, that is, the accumulated charge of the liquid crystal alignment film is slowly eliminated after being illuminated, resulting in excessive residual charge, thereby generating the problem of afterimage. As can be seen from the above, in order to meet the requirements of the current photo-aligned IPS type liquid crystal display industry, it is the goal of the technical field to provide a liquid crystal alignment agent that can form a liquid crystal display element with better flickering degree immediately after driving. Summary of the invention

[0007] One aspect of the present invention is to provide a liquid crystal alignment agent, which comprises a polymer (A) and a solvent (B). The liquid crystal alignment agent can improve the flickering degree of the prepared liquid crystal display element immediately after driving. In addition, the liquid crystal alignment agent of the present invention can selectively comprise an additive (C).

[0008] Another aspect of the present invention is to provide a liquid crystal alignment film, which is formed by using the above-mentioned liquid crystal alignment agent.

[0009] Another aspect of the present invention is to provide a liquid crystal display element, which includes the above-mentioned liquid crystal alignment film.

[0010] According to the above aspect of the present invention, a liquid crystal alignment agent is provided, and the liquid crystal alignment agent comprises a polymer (A) and a solvent (B), which are described below.

[0011] Polymer (A)

[0012] The polymer (A) of the present invention can be prepared by polymerization reaction of a tetracarboxylic dianhydride component (a) and a diamine component (b).

[0013] Preferred specific examples of the aforementioned polymer (A) may be polyamic acid polymers, polyimide polymers, polyimide block copolymers or combinations thereof. Among them, preferred specific examples of polyimide block copolymers are polyamic acid block copolymers, polyimide block copolymers, polyamic acid-polyimide block copolymers or any combination thereof.

[0014] Tetracarboxylic dianhydride component (a)

[0015] Tetracarboxylic dianhydride compound (a-1)

[0016] The tetracarboxylic dianhydride component (a) of the present invention comprises at least one tetracarboxylic dianhydride compound (a-1) represented by the following formula (I):

[0017]

[0018] In formula (I), R1 to R4 each 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 monovalent organic group having 1 to 6 carbon atoms and containing a fluorine atom, or a phenyl group, R1 to R4 are the same or different, and at least one of R1, R2, R3 and R4 is not a hydrogen atom.

[0019] In the case where R1, R2, R3 and R4 have a steric barrier structure, the obtained liquid crystal alignment agent will cause the formed liquid crystal display element to have poor flickering immediately after being driven. Therefore, R1, R2, R3 and R4 are preferably hydrogen atoms, methyl or ethyl, among which methyl is more preferred.

[0020] Specific examples of the tetracarboxylic dianhydride compound (a-1) represented by formula (I) include compounds represented by formulas (I-1) to (I-8) below. In terms of the degree of flickering immediately after driving, the compound represented by formula (I-1) is preferred.

[0021]

[0022]

[0023] The above-mentioned tetracarboxylic dianhydride compound (a-1) may be used alone or in combination of two or more.

[0024] Based on 100 mol of the total usage of the tetracarboxylic dianhydride component (a), the usage of the tetracarboxylic dianhydride compound (a-1) is 10 mol to 100 mol, preferably 20 mol to 80 mol, and more preferably 30 mol to 70 mol.

[0025] If the tetracarboxylic dianhydride component (a) does not contain the tetracarboxylic dianhydride compound (a-1), the resulting liquid crystal alignment agent will cause the formed liquid crystal display element to have poor flickering immediately after being driven.

[0026] Other tetracarboxylic dianhydride compounds (a-2)

[0027] The tetracarboxylic dianhydride component (a) of the present invention may selectively contain other tetracarboxylic dianhydride compounds (a-2). Preferred specific examples of other tetracarboxylic dianhydride compounds (a-2) include (1) aliphatic tetracarboxylic dianhydride compounds, (2) alicyclic tetracarboxylic dianhydride compounds, (3) aromatic tetracarboxylic dianhydride compounds, or (4) tetracarboxylic dianhydride compounds represented by the following formulas (V-1) to (V-6).

[0028] The (1) aliphatic tetracarboxylic dianhydride compound of the present invention includes, but is not limited to, aliphatic tetracarboxylic dianhydride compounds such as ethanetetracarboxylic dianhydride and butanetetracarboxylic dianhydride.

[0029] The (2) alicyclic tetracarboxylic dianhydride compounds of the present invention include, but are not limited to, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dichloro-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, Alicyclic tetracarboxylic acid dianhydride compounds such as 2,3,4-cyclopentanetetracarboxylic acid dianhydride, 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride, 3,3',4,4'-dicyclohexyltetracarboxylic acid dianhydride, cis-3,7-dibutylcycloheptyl-1,5-diene-1,2,5,6-tetracarboxylic acid dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride or bicyclo[2.2.2]-oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride.

[0030] Specific examples of the (3) aromatic tetracarboxylic dianhydride compound of the present invention include, but are not limited to, 3,4-dicarboxy-1,2,3,4-tetrahydronaphthalene-1-succinic dianhydride, pyromellitic dianhydride, 2,2',3,3'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyl sulfone tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 3,3'-4,4'-diphenylethane tetracarboxylic dianhydride, 3,3',4,4'-dimethyldiphenylsilane tetracarboxylic dianhydride, 3,3',4,4'-tetraphenylsilane tetracarboxylic dianhydride, 1,2,3,4-furan tetracarboxylic dianhydride, 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride, 2,3,3',4'-diphenyl sulfide tetracarboxylic dianhydride, 3,3',4,4'-diphenyl sulfide tetracarboxylic dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenyl sulfone dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenyl propane dianhydride, 3,3',4,4'-perfluoroisopropylidene diphthalic acid dianhydride, 2,2',3,3'-diphenyltetracarboxylic dianhydride, 2,3,3',4'-diphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyltetracarboxylic dianhydride, bis(phthalic acid)phenylphosphine oxide dianhydride, p-phenylene-bis(triphenylphthalic acid) Dianhydride, m-phenylene-bis(triphenylphthalic acid) dianhydride, bis(triphenylphthalic acid)-4,4'-diphenyl ether dianhydride, bis(triphenylphthalic acid)-4,4'-diphenylmethane dianhydride, ethylene glycol-bis(anhydrotrimellitate), propylene glycol-bis(anhydrotrimellitate), 1,4-butanediol-bis(anhydrotrimellitate), 1,6-hexanediol-bis(anhydrotrimellitate), 1,8-octanediol-bis(anhydrotrimellitate), 2,2-bis(4-hydroxyphenyl)propane-bis(anhydrotrimellitate), 2,3,4,5-tetrahydrofuran tetracarboxylic acid dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furyl)-naphtho[1,2-c]-furan -1,3-dione, 1,3,3a,4,5,9b-hexahydro-5-methyl-5-(tetrahydro-2,5-dioxo-3-furyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-5-ethyl-5-(tetrahydro-2,5-dioxo-3-furyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-7-methyl-5-(tetrahydro-2,5-dioxo-3-furyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-7-ethyl-5-(tetrahydro-2,5-dioxo-3-furyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-8-methyl-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-8-ethyl-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]-furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-5,8-dimethyl-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]-furan-1,3-dione, 5-(2,5-dioxotetrahydrofuranyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, etc.

[0031] According to the present invention (4), the tetracarboxylic dianhydride compounds represented by formula (V-1) to formula (V-6) are described in detail as follows:

[0032]

[0033]

[0034] In formula (V-5), N1 represents a divalent group containing an aromatic ring; r represents an integer from 1 to 2; N2 and N3 may be the same or different and may represent a hydrogen atom or an alkyl group, respectively. Preferably, the tetracarboxylic dianhydride compound as shown in formula (V-5) may be selected from the compounds shown in the following formulas (V-5-1) to (V-5-3).

[0035]

[0036] In formula (V-6), N4 represents a divalent group containing an aromatic ring; N5 and N6 may be the same or different and represent a hydrogen atom or an alkyl group, respectively. Preferably, the tetracarboxylic dianhydride compound as shown in formula (V-6) can be selected from the compounds shown in formula (V-6-1) below.

[0037]

[0038] The above-mentioned other tetracarboxylic dianhydride compounds (a-2) may be used alone or in combination of two or more.

[0039] Based on 100 mol of the total usage of the tetracarboxylic dianhydride component (a), the usage of the other tetracarboxylic dianhydride compound (a-2) is 0 mol to 90 mol, preferably 20 mol to 80 mol, and more preferably 30 mol to 70 mol.

[0040] Based on 100 mol of the diamine component (b), the amount of the tetracarboxylic dianhydride component (a) is in the range of 20 mol to 200 mol, and preferably 30 mol to 120 mol.

[0041] Diamine component (b)

[0042] The diamine component (b) of the present invention may include a diamine compound (b-1) represented by the following formula (II).

[0043] HN2·-X1-M1-A-M2-X2-NH2 (II)

[0044] In formula (II), M1 and M2 independently represent a single bond, -O-, -S-, -NM3-, an ester group, an amide group, a thioester group, a urea group, a carbonate group or a carbamate group, wherein M3 represents a hydrogen atom or a methyl group, and M1 and M2 may be the same or different; A represents an alkylene group having a carbon number of 2 to 20; X1 and X2 independently represent a divalent organic group as shown in the following formulas (III-1) to (III-19), and X1 and X2 are two different structures selected from formulas (III-1) to (III-19), wherein at least one of X1 and X2 represents a structure as shown in formula (III-17), formula (III-18) or formula (III-19).

[0045]

[0046]

[0047] In formula (III-2), X3 represents an alkylene group having 1 to 5 carbon atoms; in formula (III-14), X4 represents a hydrogen atom, a halogen atom, a methyl group, a hydroxyl group or a methoxy group; in formula (III-17), X5 and X6 each independently represent a halogen atom, a methyl group, a hydroxyl group or a methoxy group; in formula (III-18), X7 and X8 each independently represent a hydrogen atom, a halogen atom, a methyl group, a hydroxyl group or a methoxy group, and at least one of X7 and X8 is not a hydrogen atom.

[0048] It should be noted that the aforementioned two different structures selected from formula (III-1) to formula (III-19) by X1 and X2 means that X1 and X2 have different main structures (i.e., the structures shown in formula (III-1) to formula (III-19)), rather than just the difference in functional groups. In other words, if X1 and X2 have the same main structure, and the main structures of the two have different functional groups, although their chemical structures have different functional groups, these diamine compounds do not belong to the diamine compound (b-1) of the present invention. In formula (II), when X1 and X2 are the same structural formula selected from formula (III-1) to formula (III-19) (i.e., the same main structure, and the functional groups bonded to the main structure are the same or different), the obtained liquid crystal alignment agent will cause the formed liquid crystal display element to have poor flickering immediately after driving.

[0049] In formula (II), M1 and M2 are preferably a single bond, -O-, -S-, -NM3-, an ester group or an amide group, and more preferably -O-. Secondly, based on the viewpoint of liquid crystal orientation, A preferably represents an alkylene group having 2 to 6 carbon atoms, and more preferably an alkylene group having 2 to 4 carbon atoms.

[0050] In formula (III-2), X3 preferably represents an alkylene group having 1 to 3 carbon atoms, and in formula (III-14), X4 preferably represents a hydrogen atom or a methyl group.

[0051] In formula (II), if at least one of X1 and X2 does not represent a structure as shown in formula (III-17), formula (III-18) or formula (III-19), the obtained liquid crystal alignment agent will cause the formed liquid crystal display element to have poor flickering immediately after being driven.

[0052] In some embodiments, the diamine compound (b-1) may be selected from diamine compounds represented by the following formula (II-1-1) to formula (II-1-3).

[0053]

[0054]

[0055] In formula (II-1-1) to formula (II-1-3), A, M1, M2, X5, X6, X7 and X8 are defined as described above.

[0056] When the diamine compound (b-1) is selected from the diamine compounds shown in formula (II-1-1) to formula (II-1-3), the prepared liquid crystal alignment agent can further reduce the flickering degree of the formed liquid crystal display element immediately after driving.

[0057] Specific examples of the diamine compound (b-1) represented by the aforementioned formula (II) may include, but are not limited to, diamine compounds represented by the following formulas (II-2-1) to (II-2-56).

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064] In formula (II-2-16) and formula (II-2-24), the definition of M3 is as described above and will not be repeated here.

[0065] The above-mentioned diamine compound (b-1) may be used alone or in combination of two or more.

[0066] Based on 100 mol of the total usage of the diamine component (b), the usage of the diamine compound (b-1) is 5 mol to 50 mol, preferably 5 mol to 40 mol, and more preferably 5 mol to 30 mol.

[0067] If the diamine component (b) does not contain the diamine compound (b-1), the resulting liquid crystal alignment agent will cause the formed liquid crystal display element to have poor flickering immediately after being driven.

[0068] Diamine compound (b-2)

[0069] The diamine component (b) of the present invention may include a diamine compound (b-2) represented by the following formula (IV).

[0070]

[0071] In formula (IV), Z1 and Z5 each independently represent a single bond, -CH2- or -CH2CH2-; Z2 and Z4 each independently represent -CH2- or -CH2CH2-; Z3 represents an alkyl group or a cyclohexyl group having a carbon number of 1 to 6; Y1 and Y2 each independently represent a single bond, -O-, -NH-, -N(CH3)-, -C(=O)-, -C(=O)O-, -C(=O)NH-, -C(=O)N(CH3)-, -OC(=O)-, -NHC(=O)- or N(CH3)C(=O)-; Y3 represents a straight chain hydrocarbon group having a carbon number of 1 to 20, a branched hydrocarbon group having a carbon number of 3 to 20, or a cyclic hydrocarbon group having a carbon number of 3 to 20; and a represents 0 or 1.

[0072] In formula (IV), Z1 and Z5 preferably represent a single bond or -CH2-; Z2 and Z4 preferably represent -CH2-. When Z1 and Z5 are the same, Z2 and Z4 are preferably different. When Z1 and Z5 are different, Z2 and Z4 are preferably the same.

[0073] In formula (IV), Y1 and Y2 preferably represent a single bond, -O-, -C(=O)-, -C(=O)O-, -C(=O)NH-, -C(=O)N(CH3)-, -OC(=O)-, -NHC(=O)- or N(CH3)C(=O)-, and more preferably independently represent a single bond or -O-. When Y1 and Y2 independently represent a single bond or -O-, the obtained liquid crystal alignment agent can further reduce the degree of flickering of the formed liquid crystal display element immediately after driving.

[0074] Based on the availability of raw materials, Y3 may preferably be, for example, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, benzyl, n-hexadecyl or 9-fluorenylmethyl.

[0075] From the viewpoint of ease of synthesis, a is preferably 0.

[0076] Specific examples of the diamine compound (b-2) represented by formula (IV) may include, but are not limited to, diamine compounds represented by the following formulas (IV-1) to (IV-46).

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

[0083] In formula (IV-1) to formula (IV-46), Me represents a methyl group; Et represents an ethyl group; i-Pr represents an i-propyl group; Bn represents a benzyl group; and Boc represents a tert-butoxycarbonyl group.

[0084] The aforementioned diamine compound (b-2) may be used alone or in combination of two or more.

[0085] Based on 100 mol of the total usage of the diamine component (b), the usage of the diamine compound (b-2) is 1 mol to 10 mol, preferably 1 mol to 8 mol, and more preferably 1 mol to 5 mol.

[0086] When the diamine component (b) comprises the diamine compound (b-2), the prepared liquid crystal alignment agent can further reduce the flickering degree of the formed liquid crystal display element immediately after being driven.

[0087] Other diamine compounds (b-3)

[0088] The diamine component of the present invention may optionally contain other diamine compounds (b-3).

[0089] Other diamine compounds (b-3) may include, but are not limited to, 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 4,4'-diaminoheptane, 1,3-diamino-2,2-dimethylpropane, 1,6-diamino-2,5-dimethylhexane, 1,7-diamino-2,5-dimethylheptane, 1,7-diamino-4,4-dimethylheptane, 1,7-diamino-3-methylheptane, 1,9-diamino-5-methylnonane, 2,11-diaminododecane, 1,12-diaminooctadecane, 1,2-bis(3-aminopropoxy)ethane, 4,4'-diaminodicyclohexylmethane, 4,4'-diamino-3,3'-dimethyldicyclohexylamine, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienediamine, tricyclo[6.2.1.0(2,7)]-undecene dimethyl diamine, 4,4'-methylenebis(cyclohexylamine), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminobenzanilide, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 5-amino-1-(4'-aminophenyl)-1,3,3-trimethylhydroindene, 6-amino-1-(4'-aminophenyl)-1,3,3-trimethylhydroindene, hexahydro-4,7-methanoindene dimethylenediamine, 3,3'-diaminobenzophenone, 3, 4'-Diaminobenzophenone, 4,4'-diaminobenzophenone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]sulfone, 1,4-bis(4-aminophenoxy)cyclohexane, 1,5-bis(4-aminophenoxymethylene)adamantane, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 9,9-bis(4-aminophenyl)-10-hydrogen anthracene, 9,10-bis(4-aminophenyl)anthracene, 2,7-diaminofluorene, 9,9-bis(4-aminophenyl)fluorene, 4,4'-methylene-bis(2-chloroaniline), 4,4'-(p-phenylene isopropylidene) dianiline, 4,4'-(m-phenylene isopropylidene) dianiline, 2,2'-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]hexafluoropropane, 4,4'-bis[(4-amino-2-trifluoromethyl)phenoxy]-octafluorobiphenyl, 5-[4-(4-n-pentylcyclohexyl)cyclohexyl] ]phenylmethylene-1,3-diaminobenzene {5-[4-(4-n-pentylcyclohexyl)cyclohexyl]phenylmethylene-1,3-diaminobenzene}, 1,1-bis[4-(4-aminophenoxy)phenyl]-4-(4-ethylphenyl)cyclohexane {1,1-bis[4-(4-aminophenoxy)phenyl]-4-(4-ethylphenyl)cyclohexane} or other diamine compounds represented by the following formula (VI-1) to formula (VI-29).

[0090]

[0091] In formula (VI-1), F1 represents And F2 represents a steroidal group, a trifluoromethyl group, a fluoro group, an alkyl group having 2 to 30 carbon atoms, or a monovalent group derived from a nitrogen atom-containing cyclic structure such as pyridine, pyrimidine, triazine, piperidine and piperazine.

[0092] The other diamine compounds represented by the above formula (VI-1) are preferably 2,4-diaminophenyl ethyl formate, 3,5-diaminophenyl ethylformate, 2,4-diaminophenyl propyl formate, 3,5-diaminophenyl propyl formate, 1-dodecoxy-2,4-diamino-benzene, 1-hexadecoxy-2,4-diaminobenzene, 1-octadecoxy-2,4-diaminobenzene or other diamine compounds represented by the following formulas (VI-1-1) to (VI-1-6).

[0093]

[0094]

[0095] In formula (VI-2), F3 represents F4 and F5 represent an extended aliphatic ring, an extended aromatic ring or an extended heterocyclic group, and F6 represents an alkyl group having 3 to 18 carbon atoms, an alkoxy group having 3 to 18 carbon atoms, a fluoroalkyl group having 1 to 5 carbon atoms, a fluoroalkoxy group having 1 to 5 carbon atoms, a cyano group or a halogen atom.

[0096] The other diamine compounds represented by the above formula (VI-2) are preferably diamine compounds represented by the following formulas (VI-2-1) to (VI-2-13):

[0097]

[0098]

[0099] In Formula (VI-2-10) to Formula (VI-2-13), s may represent an integer of 3 to 12.

[0100]

[0101] In formula (VI-3), F7 represents a hydrogen atom, an acyl group having 1 to 5 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a halogen. P1 represents an integer from 1 to 3. When P1 is greater than 1, a plurality of F7s may be the same or different.

[0102] The diamine compound represented by the above formula (VI-3) is preferably selected from (1) P1 is 1: p-diaminobenzene, m-diaminobenzene, o-diaminobenzene or 2,5-diaminotoluene; (2) P1 is 2: 4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 2,2'-dichloro-4,4'-diaminobiphenyl, 3,3'-dichloro-4,4'-diaminobiphenyl biphenyl, 2,2',5,5'-tetrachloro-4,4'-diaminobiphenyl, 2,2'-dichloro-4,4'-diamino-5,5'-dimethoxybiphenyl or 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl, etc.; (3) P1 is 3: 1,4-bis(4'-aminophenyl)benzene, etc., and is more preferably selected from p-diaminobenzene, 2,5-diaminotoluene, 4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl or 1,4-bis(4'-aminophenyl)benzene.

[0103]

[0104] In the above formula (VI-4), P2 represents an integer from 1 to 5. The structure represented by formula (VI-4) is preferably selected from 4,4'-diaminodiphenyl sulfide.

[0105]

[0106] In formula (VI-5), F8 and F 10 They may be the same or different and each represents a divalent organic group. F9 represents a divalent group derived from a nitrogen atom-containing cyclic structure such as pyridine, pyrimidine, triazine, piperidine and piperazine.

[0107]

[0108] In formula (VI-6), F 11 、F 12 、F 13 and F 14 Each may be the same or different and may represent a hydrocarbon group having a carbon number of 1 to 12. P3 represents an integer of 1 to 3, and P4 represents an integer of 1 to 20.

[0109]

[0110] In formula (VI-7), F 15represents -O- or cyclohexyl, F 16 Represents -CH2-, F 17 represents phenylene or cyclohexylene, and F 18 represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

[0111] The diamine compound represented by the above formula (VI-7) is preferably selected from the diamine compounds represented by the following formula (VI-7-1) and formula (VI-7-2).

[0112]

[0113] Other diamine compounds represented by formula (VI-8) to formula (VI-29) are as follows:

[0114]

[0115]

[0116]

[0117]

[0118] In Formula (VI-16) to Formula (VI-19), F 19 Preferably, it is an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms. In Formula (VI-20) to Formula (VI-24), F 20 Preferred is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms.

[0119] Other diamine compounds (b-3) may preferably include but are not limited to 1,2-diaminoethane, 4,4'-diaminodicyclohexylmethane, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 5-[4-(4-n-pentylcyclohexyl)cyclohexyl]phenylmethylene-1,3-diaminobenzene, 1,3-bis(3-aminophenoxy)benzene, 1,1-bis[4-(4-aminophenoxy)phenyl]-4-(4-ethylphenyl)cyclohexane, 2,4-diaminophenyl ethyl carboxylate, p-diaminobenzene, m-diaminobenzene, o-diaminobenzene, compounds represented by formula (VI-1-1), formula (VI-1-2), formula (VI-1-5), formula (VI-2-1), formula (VI-2-11), formula (VI-7-1), formula (VI-25) or formula (VI-28).

[0120] The above-mentioned other diamine compounds (b-3) may be used alone or in combination of two or more.

[0121] Based on 100 mol of the total usage of the diamine component (b), the usage of the other diamine compound (b-3) is 40 mol to 94 mol, preferably 52 mol to 94 mol, and more preferably 65 mol to 94 mol.

[0122] Preparation method of polymer (A)

[0123] The preparation of the polyamic acid polymer of the present invention can be a general method. Preferably, the preparation method of the polyamic acid polymer comprises the following steps: dissolving a mixture comprising a tetracarboxylic dianhydride component (a) and a diamine component (b) in a solvent, carrying out a polycondensation reaction at a temperature of 0°C to 100°C and reacting for 1 hour to 24 hours, and then subjecting the reaction solution to reduced pressure distillation using an evaporator to obtain a polyamic acid polymer, or pouring the reaction solution into a large amount of poor solvent to obtain a precipitate, and then drying the precipitate by reduced pressure drying to obtain a polyamic acid polymer.

[0124] The solvent used in the polycondensation reaction may be the same as or different from the solvent (B) in the liquid crystal alignment agent described below, and there is no particular limitation on the solvent used in the polycondensation reaction, as long as it can dissolve the reactants and the products. Preferably, the solvent includes but is not limited to (1) a non-protonic polar solvent, such as N-methyl-2-pyrrolidinone (NMP), N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea or hexamethylphosphoric acid triamide, etc.; (2) a phenol solvent, such as m-cresol, xylenol, phenol or halogenated phenols. Based on 100 parts by weight of the mixture, the amount of the solvent used in the polycondensation reaction is preferably 200 to 2000 parts by weight, and more preferably 300 to 1800 parts by weight.

[0125] In particular, in the polycondensation reaction, the solvent can be used in combination with an appropriate amount of a poor solvent, wherein the poor solvent does not cause the polyamic acid polymer to precipitate. The poor solvent can be used alone or in combination of multiple types, and includes but is not limited to (1) alcohols, such as methanol, ethanol, isopropanol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol or triethylene glycol; (2) ketones, such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.; (3) esters, such as methyl acetate, ethyl acetate, butyl acetate, diethyl oxalate, diethyl malonate or ethylene glycol ethyl ether acetate; (4) ethers, For example: ethers such as diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol n-propyl ether, ethylene glycol isopropyl ether, ethylene glycol n-butyl ether, ethylene glycol dimethyl ether or diethylene glycol dimethyl ether; (5) halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene or o-dichlorobenzene; (6) hydrocarbons such as tetrahydrofuran, hexane, heptane, octane, benzene, toluene or xylene or any combination of the above solvents. Based on 100 parts by weight of the diamine component (b), the amount of the poor solvent is preferably 0 to 60 parts by weight, more preferably 0 to 50 parts by weight.

[0126] The preparation of the polyimide polymer of the present invention can be a general method. Preferably, the preparation method of the polyimide polymer first dissolves a mixture in a solution, wherein the mixture includes a tetracarboxylic dianhydride component (a) and a diamine component (b), and performs a polymerization reaction to form a polyamic acid polymer. Then, in the presence of a dehydrating agent and a catalyst, further heating is performed, and a dehydration ring-closure reaction is performed, so that the amic acid functional group in the polyamic acid polymer is converted into an imide functional group (i.e., imidization) through a dehydration ring-closure reaction, and the polyimide polymer is obtained.

[0127] The solvent used in the dehydration ring-closing reaction can be the same as the solvent in the liquid crystal alignment agent described below, so it is not described in detail. Based on the usage of the polyamic acid polymer as 100 parts by weight, the usage of the solvent used in the dehydration ring-closing reaction is preferably 200 parts by weight to 2000 parts by weight, more preferably 300 parts by weight to 1800 parts by weight.

[0128] In order to obtain a better imidization degree of the polyamic acid polymer, the operating temperature of the dehydration ring-closing reaction is preferably 40° C. to 200° C., more preferably 40° C. to 150° C. If the operating temperature of the dehydration ring-closing reaction is lower than 40° C., the imidization reaction is incomplete, thereby reducing the imidization degree of the polyamic acid polymer. However, if the operating temperature of the dehydration ring-closing reaction is higher than 200° C., the weight average molecular weight of the obtained polyimide polymer is low.

[0129] The dehydrating agent used in the dehydration ring-closing reaction can be selected from anhydride compounds, such as acetic anhydride, propionic anhydride or trifluoroacetic anhydride. Based on 1 mole of the polyamic acid polymer, the amount of the dehydrating agent used is 0.01 mole to 20 moles. The catalyst used in the dehydration ring-closing reaction can be selected from (1) pyridine compounds, such as pyridine, trimethylpyridine or dimethylpyridine; (2) tertiary amine compounds, such as triethylamine. Based on 1 mole of the dehydrating agent, the amount of the catalyst used is 0.5 mole to 10 moles.

[0130] Preferred specific examples of the polyimide of the present invention being a block copolymer are polyamic acid block copolymer, polyimide block copolymer, polyamic acid-polyimide block copolymer, or any combination thereof.

[0131] The preparation of the polyimide block copolymer of the present invention can be a general method. Preferably, the preparation method of the polyimide block copolymer first dissolves the starting material in a solvent and performs a polycondensation reaction, wherein the starting material comprises at least one polyamic acid polymer and / or at least one polyimide polymer mentioned above, and may further comprise a tetracarboxylic dianhydride component (a) and a diamine component (b).

[0132] The tetracarboxylic dianhydride component (a) and the diamine component (b) in the aforementioned starting materials are the same as the tetracarboxylic dianhydride component (a) and the diamine component (b) used in the preparation of the polyamic acid polymer, and the solvent used in the polycondensation reaction can be the same as the solvent in the liquid crystal alignment agent described below, which will not be further described here.

[0133] Based on 100 parts by weight of the aforementioned starting materials, the amount of the solvent used in the polycondensation reaction is preferably 200 to 2000 parts by weight, more preferably 300 to 1800 parts by weight. The operating temperature of the polycondensation reaction is preferably 0°C to 200°C, and more preferably 0°C to 100°C.

[0134] Preferably, the starting materials include but are not limited to (1) two polyamic acid polymers having different terminal groups and different structures; (2) two polyimide polymers having different terminal groups and different structures; (3) polyamic acid polymers and polyimide polymers having different terminal groups and different structures; (4) polyamic acid polymers, tetracarboxylic dianhydride compounds and diamine compounds, wherein at least one of the tetracarboxylic dianhydride compounds and diamine compounds has a structure different from that of the tetracarboxylic dianhydride component (a) and the diamine component (b) used to form the polyamic acid polymer; (5) polyimide polymers, tetracarboxylic dianhydride compounds and diamine compounds, wherein at least one of the tetracarboxylic dianhydride compounds and diamine compounds has a structure different from that of the tetracarboxylic dianhydride component (a) and the diamine component (b) used to form the polyimide polymer; (6) polyamic acid polymers, polyimide polymers , tetracarboxylic dianhydride compounds and diamine compounds, wherein at least one of the tetracarboxylic dianhydride compounds and diamine compounds has a structure different from that of the tetracarboxylic dianhydride component (a) and the diamine component (b) used to form the polyamic acid polymer or the polyimide polymer; (7) two polyamic acid polymers, tetracarboxylic dianhydride compounds and diamine compounds having different structures; (8) two polyimide polymers, tetracarboxylic dianhydride compounds and diamine compounds having different structures; (9) two polyamic acid polymers and diamine compounds having acid anhydride end groups and different structures; (10) two polyamic acid polymers and tetracarboxylic dianhydride compounds having amino end groups and different structures; (11) two polyimide polymers and diamine compounds having acid anhydride end groups and different structures; (12) two polyimide polymers and tetracarboxylic dianhydride compounds having amino end groups and different structures.

[0135] Without affecting the efficacy of the present invention, preferably, the polyamic acid polymer, the polyimide polymer and the polyimide block copolymer may be terminal-modified polymers after molecular weight adjustment. By using terminal-modified polymers, the coating performance of the liquid crystal alignment agent can be improved. The terminal-modified polymer can be prepared by adding a monofunctional compound to the polyamic acid polymer during the polycondensation reaction. The monofunctional compound includes but is not limited to (1) monoanhydrides, such as maleic anhydride, phthalic anhydride, itaconic anhydride, n-decylsuccinic anhydride, n-dodecylsuccinic anhydride, n-tetradecylsuccinic anhydride or n-hexadecylsuccinic anhydride; (2) monoamine compounds, such as aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-undecylamine, n-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine or n-eicosylamine; (3) monoisocyanate compounds, such as phenyl isocyanate or naphthyl isocyanate.

[0136] The polymer (A) of the present invention has a polystyrene-equivalent weight average molecular weight of 10,000 to 90,000, preferably 12,000 to 75,000, and more preferably 15,000 to 60,000, as measured by gel permeation chromatography.

[0137] Solvent (B)

[0138] The solvent used in the liquid crystal alignment agent of the present invention is not particularly limited, as long as it can dissolve the polymer (A) and any other components and does not react with them. It is preferably the same solvent used in the aforementioned synthesis of polyamic acid. At the same time, the poor solvent used in the synthesis of the aforementioned polyamic acid can also be used in combination.

[0139] Specific examples of the solvent (B) include, but are not limited to, N-methyl-2-pyrrolidone (NMP), γ-butyrolactone, γ-butyrolactam, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol n-propyl ether, ethylene glycol isopropyl ether, ethylene glycol n-butyl ether, ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, or N,N-dimethylformamide or N,N-dimethylacetamide (N,N-dimethyl acetamide), etc.

[0140] The aforementioned solvent (B) may be used alone or in combination of two or more.

[0141] Based on 100 parts by weight of the polymer (A), the amount of the solvent (B) is 800 to 4000 parts by weight, preferably 900 to 3500 parts by weight, and more preferably 1000 to 3000 parts by weight.

[0142] Additives (C)

[0143] The liquid crystal alignment agent of the present invention may selectively contain an additive (C) within the scope of not affecting the efficacy of the present invention, and the additive (C) may be an epoxy compound or a silane compound having a functional group, etc. The additive (C) is used to improve the adhesion between the liquid crystal alignment film and the substrate surface. The additive (C) may be used alone or in combination.

[0144] The epoxy compound may include but is not limited to ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N,N ,N',N'-tetracyclyl-m-xylene diamine, 1,3-bis(N,N-dicyclylaminomethyl)cyclohexane, N,N,N',N'-tetracyclyl-4,4'-diaminodiphenylmethane, N,N-cyclyl-p-cyclyloxyaniline, 3-(N-allyl-N-cyclyl)aminopropyltrimethoxysilane, 3-(N,N-dicyclyl)aminopropyltrimethoxysilane, etc.

[0145] Based on 100 parts by weight of the polymer (A), the amount of the epoxy compound used is generally 40 parts by weight or less, and preferably 0.1 to 30 parts by weight.

[0146] The silane compound having a functional group may include, but is not limited to, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilane Propyl triethylenetriamine, N-trimethoxysilylpropyl triethylenetriamine, 10-trimethoxysilyl-1,4,7-triazdecane, 10-triethoxysilyl-1,4,7-triazdecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis(ethylene oxide)-3-aminopropyltrimethoxysilane, N-bis(ethylene oxide)-3-aminopropyltriethoxysilane, etc.

[0147] Based on 100 parts by weight of the polymer (A), the amount of the silane compound used is generally 10 parts by weight or less, and preferably 0.5 to 10 parts by weight.

[0148] Based on 100 parts by weight of the polymer (A), the additive (C) may be used in an amount of 0.5 to 50 parts by weight, and preferably 1 to 45 parts by weight.

[0149] Preparation method of liquid crystal alignment agent

[0150] The preparation method of the liquid crystal alignment agent of the present invention is not particularly limited, and a general mixing method can be used, such as first mixing the tetracarboxylic dianhydride component (a) and the diamine component (b) evenly to react and form a polymer (A). Then, the polymer (A) is added with a solvent (B) and an additive (C) at a temperature of 0°C to 200°C, and stirred continuously with a stirring device until dissolved. Preferably, the polymer (A) and the additive (C) are added to the solvent (B) at a temperature of 20°C to 60°C.

[0151] Method for forming liquid crystal alignment film

[0152] The liquid crystal alignment film of the present invention is a film obtained by coating the liquid crystal alignment agent formed above on a substrate, and then drying and baking.

[0153] The substrate coated with the liquid crystal alignment agent of the present invention is selected from transparent materials, wherein the transparent materials include but are not limited to alkali-free glass, soda-lime glass, hard glass (Pyles glass), quartz glass, polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, etc. used in liquid crystal display devices. Preferably, the ITO electrode for liquid crystal driving can be formed on the substrate to simplify the process. Furthermore, for a reflective liquid crystal display with only a single-sided substrate, the aforementioned substrate can be made of an opaque material such as a silicon wafer, and the electrode in this case can be formed of a material that reflects light such as aluminum. The coating method of the liquid crystal alignment agent of the present invention can be, for example, a spin coating method, a printing method, an inkjet method, etc.

[0154] The liquid crystal alignment agent of the present invention can be dried and baked at any temperature and time after coating. Generally speaking, in order to fully remove the organic solvent contained, it is necessary to dry at 50°C to 120°C for 1 minute to 10 minutes. After that, bake at 150°C to 300°C for 5 minutes to 120 minutes. There is no special restriction on the thickness of the coating after baking, but too thin a coating will cause the reliability of the liquid crystal display to deteriorate, so the thickness of the above-mentioned coating is preferably 5nm to 300nm, and 10nm to 200nm is more preferred.

[0155] Although the liquid crystal alignment agent of the present invention can be subjected to the conventional rubbing alignment treatment, the effect is better when a photo-alignment treatment method is used.

[0156] A specific example of the photo-alignment treatment method may be, for example, irradiating the surface of the aforementioned coating with radiation polarized in a specific direction, and then heating it at a temperature of 150°C to 250°C as appropriate to give the aforementioned coating liquid crystal alignment ability. Among them, ultraviolet light or visible light with a wavelength of 100nm to 800nm ​​can be used as the aforementioned radiation, and ultraviolet light with a wavelength of 100nm to 400nm is preferred, and ultraviolet light with a wavelength of 200nm to 400nm is more preferred. Furthermore, in order to improve the liquid crystal alignment, the coating substrate may be irradiated with radiation while heating the coating substrate at 50°C to 250°C. The irradiation amount of the aforementioned radiation is preferably 1mJ / cm 2 Up to 10,000mJ / cm 2 , and 100mJ / cm 2 Up to 5,000mJ / cm 2 The liquid crystal alignment film prepared in the above manner can align the liquid crystal molecules stably in a certain direction.

[0157] The liquid crystal alignment agent of the present invention forms a liquid crystal alignment film after being subjected to pre-baking treatment, post-baking treatment and photo-alignment treatment. The pre-tilt angle of the liquid crystal alignment film is 0° to 3°.

[0158] Method for manufacturing liquid crystal display element

[0159] The present invention further provides a liquid crystal display element, which includes the aforementioned liquid crystal alignment film.

[0160] The method of manufacturing a liquid crystal display element is well known to those skilled in the art, and therefore, it is only briefly described below.

[0161] See also Figure 1 A preferred embodiment of the liquid crystal display element 100 of the present invention includes a first unit 110, a second unit 120 and a liquid crystal unit 130, wherein the second unit 120 is spaced apart from the first unit 110 and the liquid crystal unit 130 is disposed between the first unit 110 and the second unit 120.

[0162] The first unit 110 includes a first substrate 112 , an electrode 114 and a first liquid crystal alignment film 116 , wherein the electrode 114 is formed on the surface of the first substrate 112 in a comb-shaped pattern, and the first liquid crystal alignment film 116 is formed on the surface of the electrode 114 .

[0163] The second unit 120 includes a second substrate 122 and a second liquid crystal alignment film 126 , wherein the second liquid crystal alignment film 126 is formed on a surface of the second substrate 122 .

[0164] The first substrate 112 and the second substrate 122 are selected from transparent materials, wherein the transparent materials include but are not limited to alkali-free glass, soda-lime glass, hard glass (Pyles glass), quartz glass, polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, etc. used in liquid crystal display devices. The material of the electrode 114 is selected from transparent electrodes such as tin oxide (SnO2), indium oxide-tin oxide (In2O3-SnO2), etc.; or metal electrodes such as chromium.

[0165] The first liquid crystal alignment film 116 and the second liquid crystal alignment film 126 are the aforementioned liquid crystal alignment films, which function to form a pre-tilt angle for the liquid crystal unit 130 , and the liquid crystal unit 130 can be driven by the parallel electric field generated by the electrode 114 .

[0166] The liquid crystal used in the liquid crystal unit 130 may be used alone or in combination. The liquid crystal includes but is not limited to diaminobenzene liquid crystal, pyridazine liquid crystal, shiff base liquid crystal, azoxy liquid crystal, biphenyl liquid crystal, phenylcyclohexane liquid crystal, ester liquid crystal, terphenyl, biphenylcyclohexane liquid crystal, pyrimidine liquid crystal, dioxane liquid crystal, bicyclooctane liquid crystal, cubane liquid crystal, etc., and cholesterol chloride, cholesterol nonanoate, cholesterol carbonate, etc. may be added as needed. The invention relates to cholesterol-type liquid crystals such as cholesteric liquid crystals such as butyl carbonate, chiral agents such as "C-15" and "CB-15" (Merck), or ferroelectric liquid crystals such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate.

[0167] The liquid crystal display element made by the liquid crystal alignment agent of the present invention is applicable to various nematic liquid crystals, such as TN, STN, TFT, VA, IPS and other liquid crystal display elements. In addition, according to the selected liquid crystal, it can also be used in different liquid crystal display elements such as strong dielectric constant or anti-strong dielectric constant. Among the above liquid crystal display elements, it is particularly suitable for IPS type liquid crystal display elements.

[0168] The following embodiments are used to illustrate the application of the present invention, but they are not used to limit the present invention. Anyone skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0169] In order to have a more complete understanding of the embodiments of the present invention and its advantages, please refer to the following description and the corresponding drawings. It must be emphasized that the various features are not depicted to scale and are only for illustration purposes. The relevant drawings are described as follows:

[0170] Figure 1 FIG. 4 is a schematic structural diagram of a liquid crystal display element according to an embodiment of the present invention.

[0171]

Main component symbol description

[0172] 100: Liquid crystal display components

[0173] 110: Unit 1

[0174] 112: First substrate

[0175] 114: First conductive film

[0176] 116: The first liquid crystal alignment film

[0177] 120: Unit 2

[0178] 122: Second substrate

[0179] 126: Second liquid crystal alignment film

[0180] 130: Liquid crystal unit DETAILED DESCRIPTION

[0181] Preparation of polymer (A-1)

[0182] Synthesis Example A-1-1

[0183] A nitrogen inlet, a stirrer, a condenser and a thermometer are set on a four-necked conical flask with a volume of 500 ml, and nitrogen is introduced. Then, 0.87 g (0.0025 mol) of the diamine compound (b-1-4) shown in formula (II-2-12), 0.235 g (0.0005 mol) of the diamine compound (b-2-1) shown in formula (IV-3) and 5.076 g (0.047 mol) of p-diaminobenzene (b-3-1) and 80 g of N-methyl-2-pyrrolidone (hereinafter referred to as NMP) are added, and stirred at room temperature until dissolved. Next, 11.2 g (0.05 mol) of the compound (a-1-1) shown in formula (I-1) and 20 g of NMP are added, and the reaction is carried out at room temperature for 2 hours. After the reaction is completed, the reaction solution is poured into 1500 ml of water to precipitate the polymer, the obtained polymer is filtered, and the steps of washing and filtering are repeated three times with methanol. Afterwards, the product was placed in a vacuum oven and dried at 60° C. to obtain the polymer (A-1-1) of Synthesis Example A-1-1, the formula of which is shown in Table 1.

[0184] Synthesis Examples A-1-2 to A-1-15 and Comparative Synthesis Examples A'-1-1 to A'-1-4

[0185] Synthesis Examples A-1-2 to A-1-15 and Comparative Synthesis Examples A'-1-1 to A'-1-4 use the same preparation method as the method for making the polymer (A-1-1) of Synthesis Example A-1-1, the difference being that Synthesis Examples A-1-2 to A-1-15 and Comparative Synthesis Examples A'-1-1 to A'-1-4 change the type and amount of raw materials in the polymer, and their formulas are shown in Table 1 and are not described in detail here.

[0186] Preparation of polymer (A-2)

[0187] Synthesis Example A-2-1

[0188] A nitrogen inlet, a stirrer, a condenser and a thermometer are set on a 500 ml four-necked conical flask, and nitrogen is introduced. Then, 0.87 g (0.0025 mol) of the diamine compound (b-1-4) shown in formula (II-2-12), 0.235 g (0.0005 mol) of the diamine compound (b-2-1) shown in formula (IV-3), 5.076 g (0.047 mol) of p-diaminobenzene (b-3-1) and 80 g of N-methyl-2-pyrrolidone (hereinafter referred to as NMP) are added, and stirred at room temperature until dissolved. Next, 11.2 g (0.05 mol) of the compound (a-1-1) shown in formula (I-1) and 20 g of NMP are added. After reacting at room temperature for 6 hours, 97 g of NMP, 2.55 g of acetic anhydride and 19.75 g of pyridine were added, the temperature was raised to 60°C, and stirring was continued for 2 hours to carry out imidization reaction. After the reaction was completed, the reaction solution was poured into 1500 ml of water to precipitate the polymer. Then, the obtained polymer was filtered, and the washing and filtering with methanol were repeated three times, and placed in a vacuum oven and dried at a temperature of 60°C to obtain a polymer (A-2-1), the formula of which is shown in Table 1.

[0189] Synthesis Examples A-2-2 to A-2-5 and Comparative Synthesis Examples A'-2-1 to A'-2-3

[0190] Synthesis Examples A-2-2 to A-2-5 and Comparative Synthesis Examples A'-2-1 to A'-2-3 use the same preparation method as the method for making the polymer (A-2-1) of Synthesis Example A-2-1, the difference being that the types and amounts of raw materials in the polymers are changed in Synthesis Examples A-2-2 to A-2-5 and Comparative Synthesis Examples A'-2-1 to A'-2-3, and their formulas are shown in Table 1 and are not described in detail here.

[0191]

[0192]

[0193] Preparation of liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element

[0194] Example 1

[0195] 100 parts by weight of the polymer (A-1-1) prepared in Synthesis Example A-1-1 and 800 parts by weight of NMP (B-1) were weighed and stirred and mixed at room temperature to prepare the liquid crystal alignment agent of Example 1.

[0196] The liquid crystal alignment agent prepared in the above-mentioned Example 1 was spin-coated on a glass substrate, and the glass substrate had a pixel electrode, wherein the pixel electrode was an IPS driving electrode having a pair of ITO electrodes (electrode width: 10 μm, electrode interval: 10 μm, electrode height: 50 nm), and the pair of ITO electrodes had a comb-like shape, and the comb-like parts of each other were arranged in a separated and interlocking manner. Then, the glass substrate coated with the liquid crystal alignment agent was dried on a hot plate at 80°C, and after 5 minutes, it was baked in a hot air circulation oven at 250°C for 60 minutes to form a coating film with a film thickness of 100 nm.

[0197] The coating surface was irradiated with ultraviolet light of 254 nm wavelength through a polarizing plate to obtain a substrate with a liquid crystal alignment film. Then, similarly, a coating was formed on an opposite substrate and an alignment treatment was applied. The opposite substrate was a glass substrate without electrodes but with columnar spacers of 4 μm in height.

[0198] The two substrates are a set, a sealant is printed on one of them, and the other is bonded to the liquid crystal alignment film in a manner that the alignment direction is 0°. Then, the sealant is hardened to obtain an empty cell. Thereafter, liquid crystal MLC-2041 (Merck) is injected into the empty cell by a reduced pressure injection method, and the injection port is sealed, thereby obtaining the liquid crystal display element of Example 1.

[0199] The obtained liquid crystal display element was evaluated in the following evaluation method, and the results are shown in Table 2. The method for detecting the degree of flicker immediately after driving will be described later.

[0200] Examples 2 to 20 and Comparative Examples 1 to 7

[0201] Examples 2 to 20 and Comparative Examples 1 to 7 use the same preparation method for the liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element as that of Example 1. The difference is that Examples 2 to 20 and Comparative Examples 1 to 7 change the type and usage of raw materials in the liquid crystal alignment agent. Their formulas and evaluation results are shown in Tables 2 and 3, respectively, and are not further described here.

[0202] Table 2

[0203]

[0204] Table 3

[0205]

[0206] In Table 3, the types of B-1, B-2, B-3, C-1 and C-2 are as described in Table 2 and are not further described here.

[0207] Evaluation method

[0208] The degree of flicker immediately after driving

[0209] The prepared liquid crystal display element is placed between two polarizing plates with polarization axes arranged in a vertically crossed manner, and the LED backlight is turned on without applying voltage. The configuration angle of the liquid crystal display element is adjusted to minimize the brightness of the transmitted light. Then, an AC voltage with a frequency of 30 Hz is applied to the liquid crystal display element, and the VT curve (voltage-transmittance curve) is measured at the same time, and the AC voltage with a relative transmittance of 23% is calculated as the driving voltage.

[0210] The method for measuring the flicker after driving is to turn off the lit LED backlight under the temperature condition of the liquid crystal display element being 23°C, and then light it again after being placed in a dark place for 72 hours. At the same time as the backlight is turned on, an AC voltage with a relative transmittance of 23% and a frequency of 30Hz is applied. The liquid crystal display element is driven for 60 minutes and the flicker amplitude is tracked. The flicker amplitude is obtained by using a data acquisition / data recording switching device 34970A (manufactured by Agilent technologies) connected to a photodiode and an IV conversion amplifier to read the brightness value of the liquid crystal display element passing through two polarizing plates and between them. The flicker (FL) is calculated according to the following formula (VII). The lower the flicker, the better the quality of the liquid crystal display element made with the liquid crystal alignment agent.

[0211]

[0212] In formula (VII), z is the brightness value read when the device 34970A is driven by an AC voltage of 30 Hz with a relative transmittance of 23%.

[0213] ※: FL<2%.

[0214] ◎:3%>FL≧2%.

[0215] ○: 4%>FL≧3%.

[0216] △: 5%>FL≧4%.

[0217] ╳: FL≧5%.

[0218] From the results of Tables 2 and 3, it can be seen that if the tetracarboxylic dianhydride component (a) of the liquid crystal alignment agent of the present invention does not include the tetracarboxylic dianhydride compound (a-1) as shown in formula (I), the flickering degree of the liquid crystal display element formed immediately after driving is not good. Secondly, if the diamine component (b) of the liquid crystal alignment agent of the present invention does not include the diamine compound (b-1) as shown in formula (II), the flickering degree of the liquid crystal display element formed immediately after driving is not good.

[0219] If the diamine compound (b-1) shown in formula (II) has the diamine compounds shown in the aforementioned formulas (II-1-1) to (II-1-3), the flickering degree of the formed liquid crystal display element immediately after driving can be further reduced.

[0220] In addition, when the diamine component (b) of the liquid crystal alignment agent of the present invention comprises the diamine compound (b-2) represented by formula (IV), the flickering degree of the formed liquid crystal display element immediately after driving can be further reduced.

[0221] It should be added that, although the present invention uses specific compounds, compositions, reaction conditions, processes, analysis methods or specific instruments as examples to illustrate the liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element of the present invention, anyone with common knowledge in the technical field to which the present invention belongs can know that the present invention is not limited thereto. Without departing from the spirit and scope of the present invention, the liquid crystal alignment agent, liquid crystal alignment film and liquid crystal display element of the present invention may also be carried out using other compounds, compositions, reaction conditions, processes, analysis methods or instruments.

[0222] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with the profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A liquid crystal alignment agent, characterized in that: The liquid crystal alignment agent comprises: The polymer (A) is prepared by polymerization reaction of a tetracarboxylic dianhydride component (a) and a diamine component (b), wherein the tetracarboxylic dianhydride component (a) comprises at least one tetracarboxylic dianhydride compound (a-1) represented by the following formula (I), and the diamine component (b) comprises a diamine compound (b-1), and the diamine compound (b-1) is selected from the diamine compounds represented by the following formulas (II-1-1) to (II-1-3): In the formula (I), R1 to R4 each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a monovalent organic group containing a fluorine atom and having 1 to 6 carbon atoms, R1 to R4 are the same or different, and at least one of R1, R2, R3 and R4 is not a hydrogen atom; In the formula (II-1-1) to the formula (II-1-3), M1 and M2 each independently represent a single bond, -O-, -S-, -NM3-, an ester group, an amide group, a thioester group, a urea group, a carbonate group or a carbamate group, wherein M3 represents a hydrogen atom or a methyl group, and M1 and M2 are the same or different; A represents an alkylene group having a carbon number of 2 to 20; In the formula (II-1-1), X5 and X6 each independently represent a halogen atom, a methyl group, a hydroxyl group or a methoxy group; in the formula (II-1-2), X7 and X8 each independently represent a halogen atom, a methyl group, a hydroxyl group or a methoxy group; Based on 100 mol of the total usage of the tetracarboxylic dianhydride component (a), the usage of the tetracarboxylic dianhydride compound (a-1) is 10 mol to 100 mol, and based on 100 mol of the total usage of the diamine component (b), the usage of the diamine compound (b-1) is 5 mol to 50 mol; as well as Solvent (B).

2. The liquid crystal alignment agent according to claim 1, characterized in that: The diamine component (b) comprises a diamine compound (b-2) represented by the following formula (IV): In the formula (IV), Z1 and Z5 each independently represent a single bond, -CH2- or -CH2CH2-; Z2 and Z4 each independently represent -CH2- or -CH2CH2-; Z3 represents an alkylene group or a cyclohexylene group having a carbon number of 1 to 6; Y1 and Y2 each independently represent a single bond, -O-, -NH-, -N(CH3)-, -C(=O)-, -C(=O)O-, -C(=O)NH-, -C(=O)N(CH3)-, -OC(=O)-, -NHC(=O)- or N(CH3)C(=O)-; Y3 represents a straight chain hydrocarbon group having a carbon number of 1 to 20, a branched hydrocarbon group having a carbon number of 3 to 20, or a cyclic hydrocarbon group having a carbon number of 3 to 20; and a represents 0 or 1.

3. The liquid crystal alignment agent according to claim 2, characterized in that: Y1 and Y2 each independently represent a single bond or -O-.

4. The liquid crystal alignment agent according to claim 2, characterized in that: a represents 0.

5. The liquid crystal alignment agent according to claim 2, characterized in that: Based on 100 mol of the total usage of the diamine component (b), the usage of the diamine compound (b-2) is 1 mol to 10 mol.

6. The liquid crystal alignment agent according to claim 1, characterized in that: Based on 100 parts by weight of the total amount of the polymer (A), the amount of the solvent (B) used is 800 parts by weight to 4000 parts by weight.

7. A liquid crystal alignment film, characterized in that: The liquid crystal alignment film is formed by using the liquid crystal alignment agent as claimed in any one of claims 1 to 6.

8. A liquid crystal display element, characterized in that: The liquid crystal display element comprises the liquid crystal alignment film as claimed in claim 7.

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